A plant-derived compound called ailanthone reduced HSV-1 replication in several cell models and eased corneal disease in a mouse model of herpes simplex keratitis, according to the study. The researchers found that ailanthone acted mainly after the virus entered cells and linked much of this effect to reduced expression of integrin beta 2, or ITGB2, a host protein that supports viral replication. The results identify ailanthone as a potential drug candidate, but the experiments do not establish that it is safe or effective in people.

The team began by screening natural compounds and testing ailanthone in African green monkey kidney Vero cells infected with HSV-1. Concentrations of 100 to 3,000 nanomolar reduced transcription of the viral immediate-early genes ICP0 and ICP4 and the late gene gD in a dose-dependent manner. The compound also reduced plaque formation and the concentration of progeny virus released into culture. Ailanthone had a half-maximal cytotoxic concentration above 10,000 nanomolar in these cells, while its half-maximal effective concentration against viral replication was 197.4 nanomolar, giving a selectivity index greater than 50. It also suppressed HSV-1-induced increases in the inflammatory cytokine genes IL-1B and TNF-α.

Antiviral activity was subsequently observed in human corneal epithelial cells, a model more directly relevant to the tissue affected by keratitis. Ailanthone concentrations of 100 to 500 nanomolar markedly reduced the cytopathic effects of HSV-1F, lowered expression of ICP0, ICP4 and gD, and reduced the viral induction of IL-1B and TNF-α. Its effective concentration in these cells was 50.16 nanomolar, with a cytotoxicity concentration above 10,000 nanomolar and a selectivity index greater than 100. The researchers also tested the compound in human retinal pigment epithelial ARPE-19 cells, where it reduced viral gene expression, plaque formation and progeny-virus titers while showing low cytotoxicity.

Activity was not restricted to the laboratory HSV-1F strain. In ARPE-19 cells, ailanthone concentration-dependently inhibited the late gD gene in the clinical acyclovir-resistant strain HSV-1/153, whereas 1,000 nanomolar acyclovir had little effect. The compound’s effective concentration was 35.05 nanomolar against HSV-1F and 227.4 nanomolar against HSV-1/153, with selectivity indices above 100 for both strains. A time-of-addition experiment indicated that ailanthone did not prevent attachment of HSV-1 to cells. It reduced entry under one experimental schedule and had its strongest effect on post-entry replication, where it lowered gD expression.

To investigate how the compound might work, the researchers combined computational target prediction with protein-interaction network analysis. They identified 36 targets shared by ailanthone and herpes simplex keratitis, then selected ITGB2 as a highly connected hub in the resulting network and as a top candidate in molecular docking. The predicted docking score for ailanthone and ITGB2 was −8.6 kcal per mole. Computational predictions alone cannot establish direct binding, so the team also performed a drug affinity responsive target stability assay in THP-1 cell lysates. Ailanthone protected ITGB2 from digestion by the protease pronase E in a dose-dependent manner, while acyclovir did not, providing biochemical evidence consistent with a direct interaction.

Functional experiments then tested whether ITGB2 was necessary for the antiviral effect. Three independent small interfering RNAs reduced ITGB2 messenger RNA and protein in THP-1 cells. Following HSV-1 infection, this knockdown lowered gD messenger RNA and protein and reduced the number of plaques produced when culture supernatants were transferred to fresh Vero cells. The converse pattern appeared when ITGB2 was overexpressed: elevated ITGB2 increased gD expression in infected cells, and it partially counteracted the reduction in gD protein caused by ailanthone in 293T and ARPE-19 cells. Together, these loss- and gain-of-function results support the conclusion that ailanthone’s antiviral activity is mediated at least partly by lowering ITGB2.

The researchers next tested ailanthone in an acute mouse model of HSV-1 keratitis. Six-week-old male BALB/c mice received a corneal scratch followed by application of HSV-1F, then received intraperitoneal ailanthone at 1 or 5 milligrams per kilogram or acyclovir at 5 milligrams per kilogram on days 1, 3 and 5 after infection. The methods section states that six animals were assigned to each group, although the discussion says five mice per group were used in the animal experiment. The 5-milligram-per-kilogram ailanthone treatment significantly reduced clinical disease scores, improved the appearance of the cornea under normal and cobalt-blue illumination, and lowered fluorescein staining scores on days 3 and 5. Hematoxylin and eosin staining at day 6 also indicated reduced corneal inflammation, and viral titers in ocular swabs were significantly lower than in infected mice given vehicle.

Analysis of mouse corneal tissue was consistent with the proposed mechanism. ITGB2 was upregulated in the corneas of infected animals, and ailanthone reduced its fluorescence intensity in a dose-dependent manner. Acyclovir did not significantly alter corneal ITGB2 levels. The investigators interpreted this as evidence that ailanthone differs from a direct viral DNA-replication inhibitor: the data are consistent with modulation of a host dependency factor rather than action solely through a viral enzyme. However, the study did not determine precisely how binding to ITGB2 leads to lower protein abundance. The authors note that transcriptional regulation, changes in messenger-RNA stability, or enhanced protein degradation could all be involved, and dedicated experiments would be required to distinguish among them.

Several limitations constrain how far the findings can be generalized. The cell experiments used established lines, including corneal epithelial and retinal pigment epithelial cells, rather than primary human corneal cells or an intact human immune system. The animal experiment examined acute primary infection in young male mice, whereas recurrent reactivation and the inflammation associated with repeated episodes are important features of human herpes simplex keratitis. Ailanthone was administered by intraperitoneal injection, but no topical ophthalmic formulation, corneal penetration, intraocular distribution, or optimized dosing regimen was evaluated. Long-term ocular toxicity and safety under repeated exposure also remain unknown. The natural compound may additionally affect multiple targets, and compensation among integrins could limit or alter its effects. The evidence therefore supports further preclinical investigation of ailanthone and ITGB2 as a host-directed antiviral strategy, not a clinical recommendation or a claim of human therapeutic benefit.

Subject of Research: Preclinical evaluation of ailanthone as a host-directed inhibitor of HSV-1 replication and herpes simplex keratitis.

Article Title: Natural compound ailanthone alleviates herpes simplex keratitis in mice by inhibiting HSV-1 replication

Article References: Chen, L., Yang, E., Zhang, X., Zhang, L., Wu, L., Chen, S., Jin, W., Qin, Q., Chen, R., Wu, J., & Chen, D. (2026). Natural compound ailanthone alleviates herpes simplex keratitis in mice by inhibiting HSV-1 replication. Frontiers in Pharmacology, 17, Article 1937590. https://doi.org/10.3389/fphar.2026.1937590

Image Credits: AI Generated

DOI: 10.3389/fphar.2026.1937590

Keywords: HSV-1, herpes simplex keratitis, ailanthone, ITGB2, host-directed antivirals, viral replication, corneal infection, mouse model, integrin beta 2, drug resistance, Natural, compound

The PLOS One editors have issued an expression of concern for a 2024 case study concerning the digital economy, innovation factor allocation and industrial structure transformation in China’s Yangtze River Delta city cluster. The notice, published on October 21, 2026, states that the article was identified as one of a series of submissions for which the journal has concerns about the integrity or reliability of the peer-review process. Readers are advised to interpret the original study with this issue in mind.

The notice does not report a new scientific finding, identify an error in the paper or evaluate the study’s scientific validity. According to the editors, PLOS did not assess the article’s integrity or scientific validity when following up on the matter. The expression of concern therefore records a concern about the circumstances surrounding peer review rather than announcing that the study’s data, methods or conclusions have been disproved. The editors also state that they have no concerns regarding the authors’ conduct during the peer-review process.

The affected article was published in PLOS One in 2024 under the title “Digital economy, innovation factor allocation and industrial structure transformation—A case study of the Yangtze River Delta city cluster in China.” The supplied notice does not provide the study’s findings, population details, analytical methods, model estimates, uncertainty measures or specific mechanisms linking the subjects named in the title. As a result, the notice does not support conclusions about the relationship between digital-economy development, innovation factors and industrial structure in the region, nor does it establish whether any reported association or causal effect is reliable.

For the wider research record, the immediate effect is that the 2024 article is accompanied by an editorial notice questioning the integrity or reliability of its peer-review process. The notice does not provide details about the submissions or explain the specific basis for the journal’s concerns. It also does not announce a correction, replacement analysis or revised conclusion. The central status of the paper’s scientific validity remains unevaluated in the supplied material, while the issue is sufficiently significant for PLOS One to advise readers to consider it when interpreting the study.

Subject of Research: A PLOS One expression of concern concerning peer-review reliability in a Yangtze River Delta regional-economy case study.

Article Title: Expression of Concern: Digital economy, innovation factor allocation and industrial structure transformation—A case study of the Yangtze River Delta city cluster in China

Article References: The PLOS One Editors (2026). Expression of Concern: Digital economy, innovation factor allocation and industrial structure transformation—A case study of the Yangtze River Delta city cluster in China. PLOS One, 21(10), e0360867. https://doi.org/10.1371/journal.pone.0360867

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360867

Keywords: PLOS One, expression of concern, peer review, research integrity, digital economy, innovation factors, industrial structure, Yangtze River Delta, China, Expression, Concern, Digital

A retrospective study of 1,307 patients undergoing elective percutaneous vertebroplasty for osteoporotic vertebral compression fractures found that 136, or 10.4%, had a puncture-site wound event within two weeks of surgery. The composite outcome included erythema or swelling, bleeding or exudate, subcutaneous hematoma, and infection. After adjustment for patient and procedural factors, suture closure was associated with more than twice the risk of the composite outcome, while diabetes, mildly elevated international normalized ratio, and multilevel treatment were also associated with higher risk.

The findings come from consecutive patients treated at Ningde Municipal Hospital in China between January 2022 and June 2026. Patients were excluded if they underwent surgery for a new fracture, had uncontrolled coagulation disorders, received concomitant open spinal surgery, required an intraoperative incision at the puncture site, had malignant tumors or abnormal immune status, or lacked key clinical or follow-up information. The analysis therefore describes elective vertebroplasty performed within one hospital system, rather than all fracture patients or all puncture wounds treated after other forms of spine surgery.

Researchers extracted information from electronic medical records, operative and anesthesia records, laboratory reports, dressing-change notes, wound-clinic assessments, and documented telephone follow-up. All puncture sites were covered with waterproof dressings and assessed within two weeks through inpatient observation, clinical review, or telephone follow-up. A wound event was counted only when explicitly documented in the records. Erythema, swelling, bleeding, exudate, hematoma, and infection were combined into one patient-level outcome, counted once even if a patient experienced several types of event, while individual components were also summarized separately.

Closure was not assigned through a randomized comparison. The operating physician selected nonsuture or suture closure according to intraoperative bleeding, exudation, skin condition, wound tension, and routine practice. Sutured wounds were typically closed with one 3-0 Vicryl Rapide stitch. Among the 1,307 patients, 774 received nonsuture closure and 533 received sutures. An early event was recorded in 53 nonsuture cases, or 6.8%, and in 83 sutured cases, or 15.6%. The crude risk ratio for any event was 2.27, with a 95% confidence interval of 1.64 to 3.15 and a P value below 0.001.

After the researchers adjusted for closure method, diabetes, INR above 1.2, age, sex, body mass index, and multilevel treatment, the association with suturing remained. The adjusted risk ratio was 2.24, with a 95% confidence interval of 1.59 to 3.16 and P below 0.001. Diabetes was associated with an adjusted risk ratio of 1.57, with a 95% confidence interval of 1.11 to 2.21 and P equal to 0.010. An INR above 1.2, defined using the hospital laboratory’s upper reference limit, was associated with an adjusted risk ratio of 1.66, with a 95% confidence interval of 1.08 to 2.57 and P equal to 0.022. Multilevel treatment had an adjusted risk ratio of 1.73, with a 95% confidence interval of 1.03 to 2.89 and P equal to 0.038.

The component findings were concentrated in relatively common superficial manifestations rather than infection. Erythema or swelling occurred in 4.1% of patients with nonsuture closure and 10.9% of those with sutures, producing a crude risk ratio of 2.63, with a 95% confidence interval of 1.73 to 3.99. Bleeding or exudate occurred in 2.7% and 5.8% of the respective groups, with a crude risk ratio of 2.14 and a 95% confidence interval of 1.25 to 3.69. Subcutaneous hematoma was uncommon, affecting two nonsuture cases and three sutured cases, and its wide confidence interval included no difference. Infection was documented in one nonsuture case and no sutured cases, too few events to model infection separately.

Age, sex, and body mass index were not independently associated with the composite outcome in the primary adjusted model. Each additional decade of age had an adjusted risk ratio of 1.15, with a 95% confidence interval of 0.94 to 1.41 and P equal to 0.186. Female sex had an adjusted risk ratio of 0.96, with a 95% confidence interval of 0.66 to 1.39 and P equal to 0.829, while each 1 kg/m² increase in body mass index had an adjusted risk ratio of 1.07, with a 95% confidence interval of 0.99 to 1.17 and P equal to 0.091. These estimates mean that the study did not find clear independent associations for those demographic and anthropometric measures, not that they have no relationship to wound events in every clinical setting.

The suture result is particularly notable because the design cannot establish that suturing caused the additional events. The authors excluded several conditions that could make closure decisions unusual, including uncontrolled coagulation disorders, concomitant open surgery, and wounds requiring an intraoperative incision. Even so, surgeons may have selected sutures for locally difficult wounds, bleeding, exudation, poor skin condition, or excessive tension. Those unrecorded features could confound the comparison, while the fact that sutured patients may have had more wound checks or suture-removal visits could also increase the likelihood that mild redness or exudate was noticed and recorded. The finding should therefore be interpreted as an adjusted observational association rather than proof that sutures themselves produce wound inflammation or other complications.

Several other constraints limit what the study can establish. Follow-up was retrospective and varied among inpatient observation, wound-clinic examination, and telephone reporting, so assessment intensity and recording thresholds were not standardized. Very mild redness or transient bleeding may have been missed, and the records did not consistently capture event duration, patient discomfort, additional care, revisits, or hospitalization. The composite endpoint improved capture of local findings but combined conditions with different causes and severities. Only one infection occurred within two weeks, preventing meaningful analysis of surgical-site infection or later infections. The single-center design and the selected elective population also limit generalizability to open spine surgery, malignant disease, immunosuppression, or puncture sites requiring remedial closure.

Overall, the study identifies four factors associated with the short-term local wound status after elective vertebroplasty: suture closure, diabetes, elevated INR, and multilevel treatment. Its practical signal is that early observation may be especially relevant for patients with these characteristics, although the findings do not establish a clinical rule or a preferred closure technique. Because closure was clinician-selected, follow-up was not standardized, and the endpoint combined mild events with rare infection, the results point to priorities for further prospective research rather than definitive guidance. Within those limits, the observed 15.6% event rate after suturing compared with 6.8% after nonsuture closure provides the clearest signal in the cohort, while the observational design makes the mechanism unresolved.

Subject of Research: Factors associated with early puncture-site wound events after percutaneous vertebroplasty for osteoporotic vertebral compression fractures

Article Title: Factors associated with early puncture-site wound events after percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a retrospective cohort study

Article References: He, X., Huang, C., Zheng, B., Wu, X., Huang, C., Lu, S., Huang, Y., Chen, J., Huang, J., & Li, B. (2026). Factors associated with early puncture-site wound events after percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a retrospective cohort study. Frontiers in Medicine, 13, Article 1988843. https://doi.org/10.3389/fmed.2026.1988843

Image Credits: AI Generated

DOI: 10.3389/fmed.2026.1988843

Keywords: Percutaneous vertebroplasty, Osteoporotic fractures, Puncture-site wounds, Suture closure, Diabetes, Coagulation, Multilevel treatment, Retrospective cohort, Postoperative care, Factors, associated, early

Cardiovascular magnetic resonance measurements identified a hemodynamic pattern associated with death or heart-transplant referral or listing in people with Fontan circulation, according to a retrospective study of 182 patients followed at a moderate-altitude center. Patients who later experienced the composite outcome had a lower superior vena cava flow index than those who did not. In time-to-event analysis, each 0.1-liter-per-minute-per-square-meter increase in the indexed flow was associated with a 30% lower hazard of the outcome.

The association remained in an exploratory model that also included ventricular ejection fraction, but the researchers said the estimate requires prospective, multicenter validation before clinical application. The cohort comprised people who had undergone Fontan palliation between 1999 and 2021 at a tertiary institution approximately 5,118 feet above sea level. Fontan circulation passively directs systemic venous blood into the pulmonary arteries without the support of a sub-pulmonary ventricle.

Eligible participants had a clinically indicated CMR examination at least five years after Fontan completion, a threshold selected to match the center’s routine surveillance practice. For patients with multiple examinations, investigators used the last CMR obtained before an outcome or censoring. Most participants, 173 of 182, or 95%, had an extracardiac conduit Fontan circulation, and 76, or 42%, underwent a Damus–Kaye–Stansel anastomosis.

At CMR, the median body surface area was 1.43 square meters, with an interquartile range of 1.16 to 1.69 square meters. The median age at Fontan completion was 3.2 years, and the median interval between surgery and imaging was 10.9 years. Median follow-up after CMR was 4.7 years, while participants’ median home elevation was 5,221 feet above sea level.

Hypoplastic left heart syndrome was the most common underlying diagnosis, accounting for 35% of the cohort, followed by tricuspid atresia at 30%. The systemic ventricle was left-dominant in 53% and right-dominant in 47%. Magnetic resonance examinations were performed on 1.5- or 3.0-tesla scanners, with cine imaging used to assess ventricular function and phase-contrast sequences used to measure blood flow.

The primary endpoint combined death with referral or listing for heart transplantation. Fourteen patients, or 7.7% of the cohort, met that endpoint during follow-up: two died and 12 were referred or listed for transplantation. Among patients who experienced the outcome, the median time from CMR to the first qualifying event was 1.2 years, with an interquartile range of 0.5 to 2.5 years.

The median superior vena cava flow index was 0.54 liters per minute per square meter among patients with the primary outcome, compared with 0.82 liters per minute per square meter among those without it; the difference was statistically significant, with a p-value of 0.011. The superior vena cava-to-ascending-aorta flow ratio was also lower in the event group, with medians of 0.22 and 0.30, respectively. Several other CMR flow measures did not differ significantly between patients with and without the primary outcome.

These included flow indices in the ascending aorta, right pulmonary artery, left pulmonary artery and inferior vena cava, as well as calculated systemic-to-pulmonary collateral flow. Receiver operating characteristic analysis indicated that superior vena cava flow index discriminated between patients who met the endpoint and those who did not with an area under the curve of 0.74 and a 95% confidence interval of 0.56 to 0.92. A data-derived threshold of 0.66 liters per minute per square meter, selected using the Youden index, yielded 70% sensitivity and 75% specificity.

Kaplan–Meier curves showed significantly poorer event-free survival among patients below that threshold. Because the threshold and discrimination measures came from the same cohort, they are exploratory rather than externally validated clinical cutoffs. Univariable Cox proportional hazards regression found a hazard ratio of 0.70 for each 0.1-liter-per-minute-per-square-meter increase in superior vena cava flow index, with a 95% confidence interval of 0.50 to 0.92 and a p-value of 0.008.

Right-dominant ventricular morphology was also associated with a higher hazard than left-ventricular dominance, with a hazard ratio of 3.21, a 95% confidence interval of 1.00 to 10.29 and a p-value of 0.049. The investigators constructed a two-variable Cox model containing superior vena cava flow index and ejection fraction. Each one-percentage-point increase in ejection fraction was associated with an adjusted hazard ratio of 0.92, with a 95% confidence interval of 0.86 to 0.97.

Because only 14 primary events occurred, the multivariable analysis was deliberately restricted and was intended to test whether the flow association persisted beyond ventricular function rather than develop a full prediction model. Internal bootstrap analysis using 2,500 resamples produced a median hazard ratio of 0.71 for superior vena cava flow index and 0.92 for ejection fraction, close to the original adjusted estimates. Collinearity between the two variables was negligible, with a Spearman absolute correlation below 0.1, an R-squared value of 0.008 and a variance inflation factor of 1.01.

Tests did not indicate violation of the proportional-hazards assumption. Ventricular measures also differed according to morphology: in the right-dominant subgroup, patients with events had larger indexed ventricular volumes and lower ejection fraction than those without events, whereas comparable differences were not statistically significant in the smaller left-dominant event subgroup. The study does not establish why lower superior vena cava flow was associated with poorer outcomes.

One proposed explanation is that chronic hypobaric exposure at moderate altitude promotes pulmonary vasoconstriction and raises pulmonary vascular resistance, potentially restricting passive flow through the Fontan pathway. However, pulmonary vascular resistance was not directly measured, and the cohort included no sea-level comparator, so the study cannot determine whether altitude caused the observed hemodynamic pattern. Other possible contributors include anatomical differences in the superior vena cava, systemic venovenous collateral vessels that divert blood around the pulmonary vascular bed, and differences in preload or single-ventricle filling.

The findings therefore associate reduced indexed flow with an unfavorable hemodynamic state rather than demonstrate a specific underlying mechanism. Important limitations constrain the results. The retrospective, single-center design creates the possibility of selection bias, and clinically performed CMR examinations were not acquired at standardized surveillance intervals.

Selecting the last scan before an outcome or censoring may introduce reverse-causation bias because patients approaching clinical deterioration could have been imaged nearer the event. Clinically relevant potential confounders—including functional class, cardiopulmonary exercise capacity, resting oxygen saturation, natriuretic peptide levels, catheterization-derived Fontan pressure and pulmonary vascular resistance, pulmonary vasodilator therapy, arrhythmia burden and the severity of liver disease—were unavailable or not incorporated. The small number of events also leaves the multivariable estimates vulnerable to overfitting despite the deliberately parsimonious model and bootstrap resampling.

Furthermore, the predominance of fenestrated extracardiac conduit Fontan circulation limits generalizability to other surgical configurations. The results position superior vena cava flow index as a candidate prognostic marker that may complement ventricular size and ejection fraction in longitudinal assessment of Fontan circulation, but they do not establish a clinical measurement rule or treatment strategy. Prospective, multicenter studies comparing cohorts across elevations would be needed to test the temporal relationship, determine whether altitude modifies the association, and establish external validity.

The authors also identified four-dimensional flow CMR as a possible tool for characterizing three-dimensional flow patterns and energy loss within the Fontan pathway. Further work could compare imaging signatures with exercise physiology, biomarkers of end-organ dysfunction and pulmonary vascular imaging. Until those studies are completed, the association between reduced superior vena cava flow and adverse outcomes should be regarded as an exploratory finding that requires independent validation.

Subject of Research: Association between CMR-derived blood flow and adverse outcomes in people with Fontan circulation

Article Title: Cardiovascular magnetic resonance–derived hemodynamics predict adverse outcomes after Fontan palliation

Article References: Platnick, C., Frank, B., Romanowicz, J., Gonzalez De Alba, C., Chase, M., Umer, A., Chaudhuri, N. R., Awori, J., Chauhan, D., Mascio, C. E., Udassi, J. P., & Hedjazi Moghari, M. (2026). Cardiovascular magnetic resonance–derived hemodynamics predict adverse outcomes after Fontan palliation. Frontiers in Cardiovascular Medicine, 13, Article 1937933. https://doi.org/10.3389/fcvm.2026.1937933

Image Credits: AI Generated

DOI: 10.3389/fcvm.2026.1937933

Keywords: Fontan circulation, cardiovascular magnetic resonance, superior vena cava flow, heart transplantation, congenital heart disease, risk stratification, ventricular function, moderate altitude, flow quantification, retrospective cohort, Cardiovascular, magnetic

In hot weather, trees “sweat” to cool down by releasing water from their leaves or needles and then replacing it with water from the soil. But during long periods of high temperatures, trees may release more water than they can replace. To strengthen forests against heat stress and other environmental hazards, scientists have suggested adding fungi to the soil. 

Soil fungi living on tree roots are called ectomycorrhizal fungi. They help trees absorb water by expanding their root networks, and trees help the fungi by providing them with sugars for energy. This beneficial partnership is known as symbiosis. Scientists at Fujian Agriculture and Forestry University in China tested whether symbiosis with ectomycorrhizal fungi could help the pine trees Pinus massoniana survive warmer temperatures. 

For their experiment, the researchers grew pine seedlings with and without ectomycorrhizal fungi in a greenhouse under different temperature conditions. First, they grew fungi called Cenococcum geophilum for 45 days on a gel-like substance called agar. At the same time, they grew the pine seedlings for 30 days, then transferred them into pots with natural soil. 

After 15 days in the pots, the researchers spread the gel-like agar containing the fungi over small 1 x 1 centimeter (cm) areas of the pine root tips to introduce the fungi to the seedlings, a process called inoculation. They assumed that the fungal network would expand from the starting area to colonize new root tips as the seedlings grew. The team’s inoculations included 6 different C. geophilum strains and 1 fungi-free control. To simulate heat stress, the researchers replicated each of the 7 inoculations at 25°C (77°F) and 35°C (95°F). They repeated each inoculation condition in 3 pots with 3 seedlings, for a total of 126 seedlings. 

After 60 days, the researchers harvested the pine seedlings and used a microscope to count how many of their root tips had fungi. They divided the number of root tips with fungi by the total number of root tips to calculate a colonization rate. They considered seedlings with a colonization rate of 80% or higher to have successfully formed a symbiotic relationship with the fungi. Then, the researchers analyzed seedlings with an 80% colonization rate to investigate their symbiotic partnerships.

The team observed that pine seedlings grown under heat stress at 35°C were 24% to 59% smaller than those grown at 25°C, and their needles were yellow instead of a healthy green. However, the seedlings that formed a symbiotic relationship with the ectomycorrhizal fungi were greener and 80% heavier than the control seedlings. 

Investigating the trees further, the team measured 3 chemical compounds related to plant stress, including malondialdehyde (MDA), proline, and nitric oxide. Plants release MDA when damaged, so high MDA levels mean a plant is struggling. In contrast, plants release proline and nitric oxide to repair cells or hold water, so high amounts of these compounds mean a plant is healing.

To measure MDA and proline levels in the pine needles, the researchers mixed them with different acids that change color depending on the sample’s MDA or proline content. To measure nitric oxide, the researchers mixed the needles with a protein that converts the compound into a chemical that changes color. They found that inoculated seedlings at 35°C had about 30% to 40% less MDA, 15% to 30% more proline, and 150% more nitric oxide in their roots than the control seedlings. 

Finally, the researchers measured changes in gene activity in the inoculated pine seedlings. They identified active genes by analyzing RNA molecules from the pine seedling roots with a process called RNA sequencing or transcriptomics. They found that inoculating the seedlings with ectomycorrhizal fungi activated more genes related to root strength, water retention, cell defense, and general plant protection than were activated in the control seedlings. 

By combining chemical analyses with growth measurements, the team concluded that a symbiotic partnership with the ectomycorrhizal fungi helped the pine seedlings survive heat stress. They demonstrated that through prolonged heat, inoculated seedlings maintained greener needles and lower levels of stress chemicals. They suggested that ectomycorrhizal fungi could be an ecological tool to help trees stay hydrated in a warming world. They recommended that future researchers conduct field trials with inoculated trees to translate these findings into forest management strategies. 

The post Fungi help pine trees survive heat stress appeared first on Sciworthy.

The NASA Exoplanet Exploration Program (ExEP) has a curated list of 164 nearest Sun-like stars that are easily visible from Earth. This list represents the first targets for a proposed large space telescope specially designed to find life in the universe, currently known as the Habitable Worlds Observatory (HWO). 

After the HWO is completed, likely sometime in the 2040s, scientists will use the specialized telescope to directly image planets in those star systems. The telescope will search around Sun-like stars for planets in a region known as the habitable zone, where temperatures allow liquid water to exist. Scientists hope to find Earth-like planets with liquid water in the habitable zones of other stars.

While the 164 stars on ExEP’s list have qualities that make them good candidates for study, it remains unknown how many actually have terrestrial planets within their habitable zones. A team of scientists at Arizona State University used simulated data for ExEP’s 164 stars and their hypothetical planetary systems to assess which are most likely to have habitable worlds. Their results would help the HWO prioritize which star systems to observe.

The team started with a subset of 134 stars on ExEP’s list with no known exoplanets, giving researchers the freedom to simulate potential worlds around them. They used a software model called the DYNAmical Multi-planet Injection TEster (DYNAMITE) to predict the possibility that an unseen planet exists around each star by generating 100,000 simulated planetary systems around it. The simulations use mathematical formulas based on observations of real exoplanets to determine the sizes and orbital characteristics of hypothetical gas giants and rocky exoplanets. DYNAMITE then determines whether these planetary systems would be stable and include a terrestrial exoplanet in the star’s habitable zone.

The other 30 stars in the ExEP’s list have known exoplanets, but none of them are rocky planets in habitable zones. To predict whether these stars have unseen terrestrial planets in their habitable zones, the team used the same DYNAMITE process as before with the additional requirement that each star must have an exoplanet matching the one already found.

To increase the chances of finding a terrestrial planet in a habitable zone, the team also investigated potentially habitable moons orbiting gas giants in these systems. For each simulation that included a gas giant, the team inserted between 2 and 23 moons, with masses between 10% of Earth’s Moon and 50% of Earth. Then they simulated the surface temperatures of these moons based on how much starlight they receive and how strongly their host planet pulls on them. They deemed the moons potentially habitable if they were large enough to retain an atmosphere and had a temperature ideal for liquid water, even if they were not technically in their stars’ habitable zones.

For each star, the team calculated a metric based on the probabilities that the star had a terrestrial planet in its habitable zone, that the planet would remain in a stable habitable zone for at least 2 billion years, and that the star had a potentially habitable moon. They called this probability statistic a ranking metric and used it to compare star systems. 

Based on the ranking metric, the team found that the dimmer and cooler stars on their list generally had better chances of hosting a habitable-zone terrestrial planet than the brighter, hotter stars. They also found that stars without known exoplanets ranked more favorably. Around 70% of the stars with known exoplanets had less than a 1% probability of hosting a terrestrial planet in their respective habitable zones. Additionally, fewer than 0.1% of their simulated moons were habitable.

Overall, the researchers concluded that the HWO should prioritize observing cooler, Sun-like stars with no known exoplanets. They claimed that the exoplanets with known characteristics in their sample set were of sizes and in positions that made it unlikely for other exoplanets to be in their systems’ habitable zones. Even with expanded habitability criteria for moons, it would be very unlikely for HWO to find another Earth orbiting a gas-giant exoplanet. They ranked 47 stars in the highest-priority category (A Tier), 51 stars in the middle category (B Tier), and 66 stars in the lowest category (C Tier) to observe with HWO. 

At the end of their study, the team remarked that the proposed HWO represents a potential next step in the search for other Earths, but scientists still need to identify the best targets for this future telescope. The HWO telescope should be able to image rocky exoplanets directly, so thorough research to prepare a list of high-priority targets will help avoid overlooking other Earths.

The post The search for habitable worlds appeared first on Sciworthy.

For centuries, civilizations have harnessed energy from water. However, hydropower often requires large bodies of water to move heavy machinery, confining its use to rivers. But what if the electricity needed to light up your house could be generated from raindrops hitting its roof? 

To achieve this, scientists rely on electrical charges created when materials come into contact and then separate, a phenomenon called the triboelectric effect. As an example, rubbing a balloon against your hair gives them opposite charges, causing your hair to stand up and stick to the balloon. Scientists apply the same principle to make droplet-based triboelectric nanogenerators, or D-TENGS, where raindrops slide across negatively charged surfaces. As the droplets move, their positive charges gather near the surface, freeing up their negative charges. When the droplets reach a metal strip called an electrode, these negative charges flow into a circuit, generating electricity. However, water often remains on D-TENG electrode surfaces, blocking subsequent droplets and corroding the device.

Researchers at the China Three Gorges University and the Chinese Academy of Sciences approached this problem by modifying the shape of the electrodes used in D-TENGs. They proposed that a needle rather than a strip would help droplets detach quickly, allowing charge to flow into a device that uses inexpensive components. They called this design a needle electrode droplet-based triboelectric nanogenerator, or NED-TENG.

To build the NED-TENG, the researchers prepared a plastic film using a water-repellent polymer called polytetrafluoroethylene as the negatively charged surface. They inserted a copper wire through the center of the plastic film, protruding 3 millimeters (0.1 inches) from the front side to form the needle-shaped electrode exposed to raindrops. Meanwhile, they attached copper foil to the plastic film’s backside as a second electrode, completing the circuit. The team connected both electrodes to an instrument that measures electrical performance and mounted the components on an acrylic sheet, sealing it with waterproof tape.

To simulate raindrops, the team inclined the NED-TENG at 50° from a table and dispensed tap water drop by drop from 30 centimeters (12 inches) above its plastic film. Like conventional D-TENGs, the device generated electricity as droplets slid across the film and contacted the needle electrode. However, because the water touched only a small area of the needle, it easily slid off the NED-TENG, preventing the water from building up like in D-TENGs.

The researchers then evaluated and optimized the device using 2 metrics: the force driving charges through its circuit, or voltage, and how fast its charges transfer, or current. First, they compared the NED-TENG with a conventional D-TENG. The NED-TENG generated about 564 Volts (V) and 5 milliamperes (mA) of current, nearly twice the voltage and 3 times the current of the D-TENG, and enough to power small electronics like indicator lights.

Next, they varied the droplets’ release height to maximize electricity production. They found that increasing the release height from 10 to 30 centimeters (4 to 12 inches) increased both voltage and current, peaking at about 543 V and 4 mA. At greater heights, droplets splashed hard on impact, scattering the water and disrupting the charging process they observed in sliding droplets. 

Similarly, the researchers tested different device inclination angles, ranging from 10° to 70°. Their tests revealed that the device’s electrical performance increased at steeper angles and peaked at 50°, reaching 521 V and 3 mA. At steeper angles, droplets spent less time in contact with the surface, reducing electrical output. They explained that because triboelectric materials are highly sensitive, results can vary slightly between experiments, leading to individual peak values that are lower than the highest overall outputs. 

The researchers then explored how the technology might perform in a simulated rooftop installation. To reduce power fluctuations during real-world applications, they connected multiple NED-TENGs. They observed that 10 connected devices could fill a small energy-storage component within 2 minutes and power 200 LED lights.

Overall, the NED-TENGs shed water efficiently and generated more electricity than D-TENGs, while remaining simple to build. The team noted that future upscaled studies should examine how rooftop systems can direct rainwater onto the devices at optimal heights, and how droplets interact with their surfaces to improve long-term performance. With further development, these low-cost systems could turn rooftops into practical generators powered by everyday rainfall. 

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Since the 1976 Viking missions, when NASA first successfully placed uncrewed landers on Mars, scientists who study life in the universe, known as astrobiologists, have been gathering evidence to determine whether microorganisms ever lived on the red planet. It has been a challenging determination to make. Until a Mars sample return mission occurs, all necessary analyses must take place on Mars, using instruments designed as much to withstand the stresses of space travel as to collect data, which limits how thoroughly scientists can study Martian rocks. As a result, the search for evidence of microbial life on Mars is inherently incremental. 

Recently, scientists added another piece of exciting, yet inconclusive, evidence to their search. In the summer of 2024, the Mars 2020 Perseverance Rover science team was searching for signs of ancient microbial life in a 3,700-million-year-old lake bed on Mars, known as Jezero Crater. In the process, they detected complex, carbon-containing organic molecules in mudstones within a river channel that once brought water to the now-dry lake bed. 

This is not the first time complex organic molecules have been detected in Martian mudstones. However, there are 2 reasons that astrobiologists are particularly interested in this new discovery. First, these organic molecules are widely dispersed across all 4 river channel mudstones they analyzed. Second, some of the organic molecules they found are associated with minerals that are known to support microbial life on Earth. 

Widely dispersed organic molecules associated with minerals that can support microbial life are exactly what astrobiologists would expect to see if microorganisms once lived in Jezero Crater. However, organic molecules can also form through geological processes, like when gases and minerals react at high temperatures and pressures at deep-sea vents on Earth. Therefore, astrobiologists must carefully assess organic molecules to determine their origin. 

In July of 2026, more than 60 Perseverance science team members took a first step towards determining whether ancient microorganisms could have made the organic molecules found in Jezero Crater. They compared the organic molecule detections in Martian mudstones to similar detections of organic molecules in samples of known origin, including fossilized Earth life, meteorites, and minerals. 

NASA scientists detected the organic molecules in Jezero Crater with a rover instrument called Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC). SHERLOC uses a 248.6 nanometer (nm) wavelength laser to excite molecules in unknown materials. When molecules are excited, they absorb and scatter the laser light, causing characteristic shifts in the wavelength of the scattered light. 

Instruments like this, known as Raman spectrometers, detect the shifted light and display the detections as lines called spectra, which scientists use to identify the unknown molecules. The Raman spectra from the 4 mudstones in Jezero crater showed shifts of about 1600 nm, which is characteristic of complex carbon molecules. These shifts appear as bands in the spectra that are often called G-bands.

Raman spectrometers are common laboratory instruments, but most use lasers with wavelengths of 485 nm or higher, so the spectra they produce can be slightly different from SHERLOC spectra even when the laser excites the same kind of molecule. To get around this issue, the scientists compared the Mars spectra with spectra of complex carbon molecules from fossilized Earth microorganisms, coal, graphite, meteorites, and synthetic samples collected by Raman instruments using the same wavelength laser that SHERLOC uses. They found that the spectra collected on Mars overlap with at least one example from every sample type except graphite. 

These results don’t rule out the possibility that organic molecules in Jezero Crater were produced by ancient microbial life, but they can’t tell us exactly how they formed either. That determination will have to wait until the samples are brought to Earth so they can be studied with laboratory instruments.

The Perseverance team has made a small but critical contribution towards determining whether microbial life ever inhabited our closest planetary neighbor, Mars. Their efforts exemplify how the science of astrobiology and the search for possible extraterrestrial life slowly and carefully move forward. If we keep at it, humans may one day have a definitive answer to one of our most consequential questions: Are we alone?

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Carbon is the 4th most abundant element in the universe. It’s everywhere, from the air you breathe to the carbohydrates in your food to the petroleum in the Earth’s crust. Like most elements, carbon was not created by the Big Bang, but came from 2 different types of stars that fuse lighter elements together. 

Massive stars at least 8 times the Sun’s mass fuse 3 helium atoms into a carbon atom in their cores, through a mechanism called the triple-alpha process. They eventually expel this carbon into space, either through a stream of material called a stellar wind or at the end of their lives during a core-collapse supernova. 

Meanwhile, low-to-intermediate-sized stars between ½ and 8 times the Sun’s mass also induce the triple-alpha process. But unlike massive stars, they produce carbon not in their cores, but in a dense shell of helium that surrounds them during an advanced stage known as the asymptotic giant branch or AGB. AGB stars undergo cycles of swelling and contraction, during which they shed some of their material into space.

While scientists understand these processes, the contribution of each star type to the carbon supply in the universe remains uncertain. To address this, a team of scientists modeled how the chemical elements in the Milky Way Galaxy change over time with different contributions from the 2 carbon-creating processes. They then verified their findings by comparing them with the actual carbon concentration in the Milky Way.

To obtain the benchmark for the Milky Way Galaxy’s carbon content, the team turned to the catalog of stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. They selected 14,066 stars that were large and bright enough to yield reliable data but, unlike AGB and massive stars, were still at a stage of life when their newly produced carbon was still confined to their cores. The researchers used the carbon in the outer layers of these stars, known as subgiants, as a compositional record of the gas from which they formed, thereby estimating the Galaxy’s carbon content during their formation. 

The scientists started with a computer program developed by another team that models how the Milky Way’s chemistry changes over time. First, the team calculated the potential amount of carbon produced by different types of stars using estimates from earlier studies. Then, they incorporated these results into a model that accounts for how stars form, fuse elements, and release carbon into the Galaxy, using a simulation program called the Versatile Integrator for Chemical Evolution, or VICE. The researchers ran 14 versions of this model, each assuming a different contribution of carbon from AGB stars relative to massive stars.

In their computer model, the Milky Way Galaxy began as a set of 200 concentric rings, each containing its own population of stars, different speeds at which stars form, and varying amounts of gas available to form new stars. The team then stitched these rings together by having stars migrate between them. They allowed these model Galaxies to settle over 10 billion years, then picked a random sample of 14,066 simulated stars to compare their carbon content with carbon in the same number of observed subgiants from APOGEE.

The team’s model most closely reproduced the actual carbon content of the Milky Way’s subgiant stars when AGB stars contribute between 10% and 40% of the Galaxy’s carbon, with the strongest agreement occurring at 15% to 30%. Even though they found that massive stars are the dominant source of carbon, they also found that smaller AGB stars could produce carbon more efficiently than previously thought, though they take longer to become carbon sources than their larger counterparts.

The team concluded that their estimates of how much carbon comes from AGB and massive stars provide a benchmark for future studies, as the connection between the production of elements inside stars and the processes by which those same stars lose mass remains poorly understood. They suggested that future researchers analyze larger sample sizes, examine other galaxies, and use data from future surveys to better understand the chemical history of the universe.

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Electric vehicles (EVs) use high-powered rechargeable batteries to store electrical energy that powers their motors. Most EV batteries use a specific mixture of metals to hold the battery’s charge, called nanoscale lithiated nickel manganese cobalt oxides, aka NMC materials. NMC materials can store a large amount of energy, making them ideal for batteries, but the metals themselves can be toxic in soil and water if the batteries are not properly recycled.  

NMC batteries leave behind a specific combination of toxic metals, so researchers can study how bacteria respond to this waste when it enters the environment. By understanding how bacteria adapt to toxic metals, scientists hope to predict how new technologies like EV batteries will affect the environment. 

In 2019, a team of researchers from the University of Minnesota reported that a common soil bacterium called Shewanella oneidensis can rapidly evolve resistance to NMC materials, but they didn’t know how. True beneficial gene evolution usually develops over thousands of generations, but Shewanella oneidensis adapted much more quickly. The team recently conducted a follow-up study to determine the genetic mechanisms behind this bacterium’s unique metal resistance.

They started by analyzing the complete DNA sequences of 33 Shewanella colonies that were resistant to either pure NMC waste or individual metals like nickel and cobalt, using a process called whole-genome sequencing. They expected to find DNA mutations in genes that control how bacteria take up and expel toxic metals that would give the resistant Shewanella an advantage in surviving NMC metal toxicity. However, they didn’t find any DNA mutations in metal-related genes. Instead, they found that a specific DNA region was duplicated 10 to 15 times in all 33 NMC-resistant or metal-resistant colonies. This result suggested to the researchers that a temporary adaptation, not true gene evolution, was responsible for the bacteria’s metal resistance. 

The researchers wanted to know more about the duplicated DNA region in metal-resistant Shewanella, so they focused on 2 gene duplication mechanisms that might serve as temporary adaptations in Shewanella. The first mechanism directly duplicates DNA regions to create extra copies of a gene, via a process called gene duplication amplification. The second mechanism moves DNA segments, called mobile genetic elements, into different DNA sections to create extra copies of a gene. 

To test whether either of these mechanisms was causing the gene duplication in Shewanella, the team grew the bacteria in different liquid media containing only cobalt, only nickel, or cobalt and nickel together. The researchers used a technique that measures the exact amount of DNA in a given sequence, called quantitative polymerase chain reaction (qPCR), to calculate how many duplicated DNA regions were in each genome sequence. They found that neither cobalt nor nickel alone triggered DNA duplication. But the bacteria grown in the media with cobalt and nickel together had 8 additional copies of the DNA region. This suggested that something about the combination of nickel and cobalt triggered gene duplication. 

To determine whether this gene duplication only occurred with nickel and cobalt, the team substituted copper and zinc for nickel in the growth media. They exposed Shewanella cells to different combinations of these metals using a grid pattern in a 96-well plate, a technique called a checkerboard assay. Then they repeated the qPCR process to measure the duplicated DNA region. They found that no other combinations of metals triggered gene duplication, suggesting that nickel and cobalt are especially toxic together, and that the gene duplication responds to this combined toxicity.

Finally, the researchers identified the function of the duplicated DNA region. They found that one of the genes within the region turned on a special protein that pushes metal ions and other toxins out of the cell, called an efflux pump protein. The team hypothesized that this efflux pump protein was responsible for removing cobalt and nickel from the bacteria’s cells. To test this theory, they grew modified Shewanella cells without the efflux pump gene in media containing cobalt, nickel, or cobalt and nickel together. They found that the modified bacteria grew well in the nickel-only treatment, but didn’t grow in the cobalt-only or combined treatments, which indicated that the efflux pump protein is necessary for Shewanella to resist cobalt toxicity. 

Based on their experiments, the team concluded that nickel and cobalt together trigger a gene duplication event in Shewanella oneidensis. This gene duplication event increases the number of efflux proteins in Shewanella that can expel cobalt and underlies its unique NMC resistance. They suggested that future researchers study temporary adaptations similar to gene duplication in bacteria to track how they respond to electronic waste and other new technologies.

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In March 2023, Southern California experienced heavy storms after almost 20 years of drought. Sixteen of these came from long, narrow regions of concentrated water vapor moving through the air, known as atmospheric rivers. During droughts, groundwater supplies up to 60% of the total water to the Greater Los Angeles area, so researchers think that stormwater from the 2023 events could have recharged groundwater reserves for future use. However, scientists lack adequate tools to assess how much groundwater is in the subsurface.

To overcome this challenge, researchers from California and Texas developed a new method to study deep groundwater. California gets a large number of earthquakes, so it has over 450 stations around the state to monitor the associated vibrations, referred to as seismic waves. To study how much the 2023 storm recharged the groundwater in the Greater Los Angeles area, the team used a tool called seismic-DI, which employs these seismic waves to estimate how much groundwater is stored at different depths. 

Seismic-DI works by measuring how fast seismic waves move through the Earth, known as their seismic velocity. The researchers explained that the Greater Los Angeles area is a very crowded city, so it produces an abundance of seismic waves. They measured changes in the seismic velocities of these underground waves to see where the groundwater is full of water, or saturated, versus partially full, or unsaturated. They used 20 years of these data to produce graphs that record changes in groundwater storage at different depths, known as hydrographs.

To validate the accuracy of seismic-DI, the researchers also compared their seismic hydrographs with groundwater thickness data from a NASA mission known as the Gravity Recovery and Climate Experiment, or GRACE. GRACE consists of 2 satellites that measure changes in Earth’s gravity, which reflect surface water and groundwater storage. Both their seismic hydrographs and the GRACE groundwater data demonstrated that the Greater Los Angeles region experienced an increase in groundwater storage from stormwater in the winter, and a reduction in groundwater storage during the dry summer. 

The team’s hydrographs showed that the 2023 storms saturated the Greater Los Angeles area groundwater down to 35 meters (114 feet), but it was abnormally dry at 200 meters (656 feet), and at a severe drought at 450 meters (1,476 feet). The GRACE data similarly demonstrated that the subsurface is in severe drought. Combined, these data indicated the 2023 storms helped the Greater Los Angeles area recover up to 90% of its groundwater at depths of 50 meters (164 feet) since the 2006-2022 drought. However, it recovered only about 40% at 75 meters (246 feet) and 20% to 30% at 100 meters (328 feet).

They concluded that the 2023 atmospheric river events recharged only shallow groundwater reserves in the Los Angeles area. As a result, they suggested future researchers consider deep groundwater reserves for a more complete assessment of total regional water deficits. While this study demonstrated that seismic-DI can successfully reveal spatial changes in groundwater and drought at depth, the team acknowledged that contributing factors like the amount, rate, and spatial variability of groundwater reserves remain targets of future work. 

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More than 90,000 tons of radioactive waste are stored on-site at nuclear power plants awaiting permanent disposal. Nuclear waste releases unstable forms of uranium and other elements, called radionuclides. Long-term exposure to radionuclides can cause cancer, so environmental safety regulations require that nuclear waste be made inaccessible for at least 1 million years. Thus, researchers are evaluating possible ways to store this waste permanently. 

One proposal is to store nuclear waste thousands of feet below ground in rock formations called deep geological repositories, or DGRs, to seal in radionuclides. Scientists can’t see into the future, so instead they look to the past to determine how well DRGs could work. A team of researchers from Canada recently analyzed uranium deposits that have existed for billions of years as an analog for how nuclear waste behaves deep underground.

Past researchers found that uranium deposits in ideal DGR conditions, with their protective casings intact, will stay contained for more than a billion years. However, these conditions require a stable geological environment. This team instead focused on uranium deposits in non-ideal conditions. They studied the Canadian Kiggavik uranium deposits, which occur in cracked bedrock approximately 500 meters (1,600 feet) below the surface. The team claimed these conditions are similar to DRGs with broken protective casings.

The team knew from previous work that most of the uranium minerals in the Kiggavik deposits are more than 274 million years old, but about 10% are less than 1 million years old. They found that these younger uranium minerals occurred alongside clay minerals surrounding the older uranium minerals and within open fractures. The researchers interpreted the older uranium as the source material of the younger uranium because of their proximity. They concluded that water must have infiltrated the deposits and interacted with older minerals, transporting uranium and forming new, younger minerals.

To determine the source of water infiltration, the researchers compared the chemistry of clay minerals formed alongside the younger uranium with modern snow in the Kiggavik region. They looked at the number of neutrons, or isotopes, in hydrogen atoms within the clay minerals, and found heavy values matching those of fresh water. These values indicated that snow or glacial meltwater was the source, rather than underlying bedrock or seawater. 

To determine when the water infiltrated over the last million years, the researchers used uranium-thorium dating to find when the radionuclides were mobilized. This dating method shows when uranium was removed from the original minerals by measuring how much its concentration was reduced by water infiltration. They found that the dates of these radionuclide mobilizations clustered into 5 separate water-infiltration events that occurred from 36 to 470 thousand years ago. 

Comparing these dates with existing climate records, the researchers found that the water infiltration events overlapped with periods when glaciers covered the ground surface. Normally, water can’t travel thousands of feet underground. But, like a hydraulic press, a glacier pushes water at its base downward. If the water encountered cracks in the ground, the pressure could inject it to the depth of the uranium deposit.

Next, the researchers wanted to measure how quickly radionuclides left the deposit. They measured the maximum distance between younger and older uranium minerals and used the age of the most recent water-infiltration event to estimate the fastest speed at which the radionuclides could have moved. They determined this maximum speed to be 0.0014 millimeters (0.000055 inches) per year. At that rate, they calculated it would take 360 million years for uranium radionuclides to travel 500 meters from a DGR at the same depth as the Kiggavik uranium deposits to the surface. This timescale far exceeds the necessary 1 million years for nuclear waste containment.

The team concluded that if glaciers were to return to Kiggavik, the uranium deposits wouldn’t experience substantial radionuclide movement, even in contact with glacial meltwater. Similarly, if a DGR has broken protective casings, radionuclides would be moving too slowly to reach the surface even if water leaked into it. They suggested their findings reduce constraints on viable DGR sites and could help ensure the long-term secure storage of nuclear waste.

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Astronomers and astrobiologists use a wide range of tools in their search for extraterrestrial life. Probes, satellites, and rovers take photographs and collect data on the geology and chemistry of planets and moons in the solar system. Radio telescopes sweep the sky, looking for signals from intelligent civilizations. And telescopes like the JWST can observe the atmospheres of distant exoplanets, potentially finding ones similar to Earth’s. 

A limitation of these methods is that they assume life on other worlds is fundamentally similar to life on Earth, requiring the same balance of molecules in the atmosphere, producing the same chemicals for their metabolic processes, or developing technologies analogous to those humans make. While researchers use these assumptions as baseline markers to look for, assuming such similarities might lead them astray. Scientists looking for life using too narrow a set of parameters might miss life unlike Earthlings. Or they might mistake coincidentally similar geological, chemical, or astronomical processes for having been made by living things.

So, to complement techniques that assume alien life resembles life on Earth, scientists also consider approaches that detect signs of life while making as few assumptions as possible about what it could look like, known as agnostic biosignatures. One of these life signs with few assumptions is complexity. Though it can be difficult to quantify precisely, living things tend to create more complex systems than nonliving things. A team of researchers recently tested whether living and nonliving worlds could be distinguished solely by examining the complexity of the light-reflection patterns from their surfaces.

For this, the team treated Earth and Mars, similar planets but one with life and one without, as stand-ins for exoplanets around other stars. They collected data on the light reflected off both planets’ surfaces from a space station monitoring Earth, known as the Deep Space Climate Observatory or DSCOVR, and an orbiter around Mars observing its atmosphere, known as the Hope Probe. 

The team identified 3 nearly identical wavelengths of light that these machines observe from their respective planets. From the machine databases, they collected measurements of how much light each planet reflected, called its reflectance, at these 3 wavelengths over 486 local days. By using only individual wavelengths of light rather than full photographs, the team claimed that, if their test worked, researchers could apply it to distant exoplanets that cannot be photographed in detail.

Without looking for any particular chemical or signal, the team compared these measured reflectances using a series of statistical tests to determine the variation and randomness in their reflected light, which they considered representative of the complexity of the planets’ surfaces. The researchers found that of the 27 complexity metrics they tested, Earth scored higher than Mars on 25, Mars scored higher than Earth on 1, and the planets scored the same on 1. So, even though both planets have rocky surfaces with atmospheres, weather, and cyclical changes, the one with life is measurably more intricate and dynamic, and the researchers found this difference detectable even with a small stream of light at great distances.

The researchers claimed their test demonstrated that complexity could be a valid agnostic biosignature, with caveats. One is that Earth is quite distinct from Mars, in that it has oceans and a relatively thick atmosphere. This means that processes like making and dispersing clouds and the sharp contrast between land and water could add complexity to Earth’s measurements without direct ties to living things. 

They suggested 2 possible explanations for how these complicating factors relate to life on Earth. Either life allows Earth to have these factors, or Earth is inherently complex regardless of life, and therefore it can’t be used to assess how life leads to measurable complexity. To say which is the case, one would have to replicate this test with a lifeless copy of Earth. However, the team argued that Earth’s biosphere is unlikely to be wholly unrelated to its water cycle.

To bolster the validity of their methods, the team plans to expand their sample of planets to include Venus, Saturn’s moon Titan, and simulated exoplanets with modeled biochemistry and atmospheres. If the model holds up, their methodology could represent a new category of mission to find alien life, with long searches for variations in reflected light uncovering properties of distant worlds that would otherwise go unnoticed.

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Waterfalls play an essential role in river development and landscape evolution. Researchers are particularly interested in how abrupt changes in the steepness of a river channel, also called knickpoints, develop. Knickpoints vary in size and can be as small as your index finger or as large as Niagara Falls. Researchers from Virginia hypothesized that waterfalls, a type of knickpoint, can influence erosion when a river channel is cut into solid rock, called bedrock. 

The researchers wondered whether fractures and other pre-existing weaknesses can influence how water removes rock slabs from a river channel, via an erosional process called plucking. Fractures can form in many different orientations, but the researchers focused on 3. Imagine a flat tabletop that represents a riverbed. Fractures that are parallel to the flat tabletop are called horizontal fractures. If you tip the table so the low end points downstream, that’s the direction of downstream-dipping fractures. If you tip the table so the low end points upstream, that’s the direction of upstream-dipping fractures. 

First, the researchers tested how fracture orientation changed erosion before an established knickpoint. They used a man-made channel, called a flume, to simulate a natural river system. To set up the experiment, they glued layers of small tiles about the size of an adult’s thumbnail to a plastic frame and put it in the flume. Then, they placed a layer of unglued tiles upstream of the knickpoint. 

To begin the experiment, the researchers incrementally increased the amount of water flowing through the flume every 5 minutes until they reached a maximum flow or all the loose tiles were “eroded.” They considered a tile to be “eroded” once it was transported over the knickpoint and downstream. The researchers measured the water depth at a fixed point upstream of the knickpoint, the number of tiles eroded through plucking, and the volume of water. They repeated this 8 times for each fracture orientation.

The team found differences in the amount and timing of erosion between the 3 orientations. In particular, they saw that erosion began at lower water speeds for horizontal beds than for tilted beds. Based on the observed erosion rates, they concluded that horizontal beds are the most susceptible to erosion, while upstream-dipping beds are the most resistant, and downstream-dipping beds fall between the 2. 

The researchers then tested how a knickpoint would develop and influence water flow if all of the tiles were unglued and free to move. They individually stacked almost 5,000 unglued tiles across the channel. Before starting the experiment, they filled the flume slowly with water to submerge all of the tiles without moving them. Then, they increased the water’s speed to start erosion. Instead of collecting measurements as they did in the first experiment, the researchers filmed this experiment and observed how the knickpoint shape changed and how plucking occurred. 

The researchers observed that the plucked tiles in this experiment formed piles downstream of the knickpoint in a process known as armoring. This armor of tiles, which represents loose rocks near a waterfall in a natural setting, prevents erosion of the underlying river bed. Only when the water transports the armor downstream can it erode the bedrock and develop a knickpoint.

Unlike the first experiment, researchers found no differences in erosion between fracture orientations in this experiment, but did observe differences in armoring. They found that upstream-dipping beds had the least armoring because water quickly transported piles of tiles near the waterfall downstream. Downstream-dipping beds had the most armoring, and their eroded tiles took longer to move downstream. 

The team concluded that waterfalls will erode at different rates based on their fracture orientation and armoring processes. The orientation of bedrock fractures also impacts the shape of the waterfall and the river channel around it. So the next time you see a large waterfall, consider that it may have started as a small fracture the size of your thumbnail.

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A wildlife camera can report a healthy battery level indoors, then shut down after one freezing night in

A team of researchers at McMaster University have produced a new plant-based, edible scaffold for cultivated meat that

The closer two people grow, the more alike their brains work – or so the assumption goes. Two

A Rutgers-led international team identifies 36 genetic risk factors, offering new insights for future treatments. A Rutgers-led international

Billions of people still suffer from hunger and food insecurity worldwide. Meanwhile, microbial contamination causes a third of global food waste annually, resulting in major economic losses and illnesses. Although antibiotics and pesticides help control contamination, their excessive use can promote bacterial resistance or leave toxic residues. 

One alternative uses materials that generate highly reactive forms of oxygen when exposed to light, called photocatalysts, to prolong food freshness. These molecules kill bacteria by damaging their cell components in a process called photodynamic inactivation or PDI. However, current PDI systems rely on energy-intensive lasers and long exposure times because the bacteria’s protective cell membranes block reactive oxygen molecules. As a result, the systems don’t kill bacteria effectively and risk overheating food, affecting its freshness and nutritional value.

Scientists at Zhejiang University in China thought that it would be possible to achieve a PDI system using accessible, free sunlight with the right photocatalyst. Moreover, they also wanted to integrate this photocatalyst into food packaging to combat microbes during storage. 

To make the photocatalyst, the researchers mixed water with a glue-like plant fiber that provides structural support, called pectin, and a chemical from plant seeds that supplies phosphorus, called phytic acid. Then they heated the mixture in a sealed reactor at 220ºC (428ºF) for 5 hours to form tiny structures composed of a carbon core surrounded by a phosphorus-rich shell called phosphorus-modified carbonized polymer dots or PCDs.

To incorporate the PCDs into film packaging, the researchers dissolved equal amounts of a plant fiber from konjac, called glucomannan, and another plant-derived molecule, called carboxymethylcellulose, in warm water to form a network of entangled molecular chains. Then, they added 1.5 milligrams of PCD per milliliter to this mixture, which linked the chains together like molecular fasteners. Finally, they added a moisture-binding chemical called glycerin to prevent brittleness. The researchers cast this mixture onto separate Petri dishes and dried them, forming thin, plastic-like PCD films.

To test the films, the researchers placed Escherichia coli bacteria between 2 sterilized film sheets and exposed the samples to either darkness or simulated sunlight for 20 minutes. They then transferred the microbes onto agar plates and incubated them for 15 hours, allowing surviving bacteria to form visible colonies. They compared the number of bacterial colonies with those of untreated samples to calculate the percentage of bacteria the films eliminated in each environment. 

Tests under darkness showed that the films eliminated about 60% of the bacteria. The researchers attributed this result to the positive electrical charge of PCDs, which attracts the bacteria’s negatively charged cell surfaces. The electrical attraction stresses their cell membranes, interfering with essential life processes. This result suggested that the films use a separate charge-based antibacterial mechanism apart from PDI, which requires light to work.

Under simulated sunlight, the films eliminated nearly 100% of the bacteria. The researchers identified 2 principal mechanisms causing this. First, the PCDs acted as tiny heaters that generated localized heat, which stretched holes in the bacterial membranes, allowing contents to leak out of their cells through a process called photoporation. Second, the PCDs generated reactive oxygen molecules that could then penetrate the bacteria. Once inside the cells, these molecules irreversibly damage the bacteria’s internal components and genetic material through PDI. 

The researchers also investigated whether PCD films could serve as food packaging by using them to wrap fresh strawberries. Compared with conventional nonbiodegradable polyethylene packaging where visible rotting occurred, the PCD films kept the strawberries fresh for more than 4 days by suppressing bacterial growth and regulating moisture levels. When the team tested whether the films were toxic, they found that the films are safe for humans and compatible for food applications. They also buried the films in soil for 24 days and found that they degraded by 78%, demonstrating biodegradability suitable for packaging fresh foods.

The team concluded that PCD films could be a biodegradable food packaging that combines plant-based materials with multiple antibacterial strategies. The films retained antibacterial activity in darkness and became more effective under sunlight through the combined effects of photoporation and PDI. These findings demonstrated that by combining multiple mechanisms into a single material, researchers can create multifunctional food packaging that remains effective across different storage conditions.

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A tiny chemical difference helps make RNA better than DNA at condensing into liquid-like droplets under high temperatures