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Global potent greenhouse gas nitrous oxide (N2O) emissions from soil are accelerating, with increases in the proportion of reactive nitrogen emitted as N2O, i.e., N2O emission factor (EF). Yet, the primary controls and underlying mechanisms of EFs remain unresolved. Based on two independent but complementary global syntheses, and three field studies determining effects of acidity on N2O EFs and soil denitrifying microorganisms, we show that soil pH predominantly controls N2O EFs and emissions by affecting the denitrifier community composition. Analysis of 5438 paired data points of N2O emission fluxes revealed a hump-shaped relationship between soil pH and EFs, with the highest EFs occurring in moderately acidic soils that favored N2O-producing over N2O-consuming microorganisms, and induced high N2O emissions. Our results illustrate that soil pH has a unimodal relationship with soil denitrifiers and EFs, and the net N2O emission depends on both the N2O/(N2O + N2) ratio and overall denitrification rate. These findings can inform strategies to predict and mitigate soil N2O emissions under future nitrogen input scenarios.

AbstractMatrix metalloproteinase-2 (MMP-2) is a key biomarker involved in various pathological processes, so its sensitive and selective detection is of great clinical significance. A fluorescent sensor for the detection of MMP-2 was successfully designed based on the inner filter effect (IFE) between carbon dots (CDs) and gold nanoparticles (AuNPs). In the presence of MMP-2, peptide chains are hydrolyzed, releasing short peptides that contain thiol groups and positive charges, thereby inducing the aggregation of AuNPs. This aggregation disrupts the IFE between AuNPs and CDs, leading to a significant enhancement of the fluorescence. By monitoring the change in fluorescence intensity of CDs, the concentration of MMP-2 was accurately determined. The sensor exhibited a linear response across the concentration range from 1.0 to 150 ng/mL, with a detection limit as low as 0.23 ng/mL, which is lower than those of previously reported methods. Furthermore, the sensor demonstrated minimal interference from coexisting biochemical substances for MMP-2 in human serum. Notably, the sensor was successfully applied to determine MMP-2 in human serum, showing satisfactory recovery rates ranging from 98.8 to 1106.0%. In conclusion, this fluorescent sensor offers high selectivity and sensitivity for MMP-2 detection, making it a promising tool for clinical diagnosis of related diseases. [ABSTRACT FROM AUTHOR]

Machine learning (ML) is becoming one of the most anticipated methods in predicting consumer demand. However, it is still uncertain how ML methods perform relative to traditional econometric methods under different dataset scales. This study estimates and compares the out-of-sample predictive accuracy of household budget share for organic fresh produce using two parametric models and six ML methods under regular and large sample sizes. Results show that ML method, particularly Logistic Elastic Net, performs better than econometric models under regular sample size. Contrarily, when dealing with big data, econometric models reach to same accuracy level as ML methods whereas random forest presents a possible overfitting problem. This study illustrates the competence of ML methods in demand prediction, but choosing the optimal method needs to consider product specifics, sample sizes, and observable features. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined factors associated with immediate antiretroviral therapy (ART) initiation among newly diagnosed people living with HIV (PLHIV) aged 18 years and above between May 2018 and June 2019 at six study sites in Guangdong Province, China. Topics include characteristics of the study participants, factors associated with immediate ART initiation among newly diagnosed PLHIV in Guangdong Province, and limitations of the study.

Transfer learning is an essential tool for improving the performance of primary tasks by leveraging information from auxiliary data resources. In this work, we propose Adaptive Robust Transfer Learning (ART), a flexible pipeline of performing transfer learning with generic machine learning algorithms. We establish the nonasymptotic learning theory of ART, providing a provable theoretical guarantee for achieving adaptive transfer while preventing negative transfer. Additionally, we introduce an ART‐integrated‐aggregating machine that produces a single final model when multiple candidate algorithms are considered. We demonstrate the promising performance of ART through extensive empirical studies on regression, classification, and sparse learning. We further present a real‐data analysis for a mortality study. [ABSTRACT FROM AUTHOR]

In collaborative learning, learners coordinate to enhance each of their learning performances. From the perspective of any learner, a critical challenge is to filter out unqualified collaborators. We propose a framework named meta clustering to address the challenge. Unlike the classical problem of clustering data points, meta clustering categorizes learners. Assuming each learner performs a supervised regression on a standalone local dataset, we propose a Select-Exchange-Cluster (SEC) method to classify the learners by their underlying supervised functions. We theoretically show that the SEC can cluster learners into accurate collaboration sets. Empirical studies corroborate the theoretical analysis and demonstrate that SEC can be computationally efficient, robust against learner heterogeneity, and effective in enhancing single-learner performance. Also, we show how the proposed approach may be used to enhance data fairness. for this article are available online. [ABSTRACT FROM AUTHOR]

Cuticular proteins (CPs) are a large family and perform a variety of functions. However, the physiological roles of cuticle protein 21-like (Cpr21L) in the brown planthopper (Nilaparvata lugens, BPH), one of the most destructive insect pests of rice, are largely unclear. In this study, Cpr21L was revealed to be expressed in both BPH nymphs and adults, and the mRNA expression level was much higher in male adults than female adults. Spatially, the expression of Cpr21L in the testis was higher than in the ovary. The RNA interference (RNAi) of Cpr21L seriously decreased nymph survival, and no individual survived 8 days post-dsCpr21L injection. The RNAi of Cpr21L in adults also decreased the fertility of males, especially in the dsCpr21L♂ × dsGFP♀ group. The average number of eggs laid by one female in this group significantly decreased by 50.1%, and the eggs' hatchability decreased from 76.5% to 23.8% compared with the control (dsGFP♂ × dsGFP♀). Furthermore, observations under a stereomicroscope showed that the RNAi of Cpr21L severely impaired the development of the testes. Therefore, Cpr21L is essential for the nymphal survival and male fecundity of BPH, thus providing a possible target for pest control. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) plays a vital role in biogeochemical processes and in determining the responses of soil organic matter (SOM) to global change. Although the quantity of soil DOM has been inventoried across diverse spatio‐temporal scales, the underlying mechanisms accounting for variability in DOM dynamics remain unclear especially in upland ecosystems. Here, a gradient of SOM storage across 12 croplands in northeast China was used to understand links between DOM dynamics, microbial metabolism, and abiotic conditions. We assessed the composition, biodegradability, and key biodegradable components of DOM. In addition, SOM and mineral‐associated organic matter (MAOM) composition, soil enzyme activities, oxygen availability, soil texture, and iron (Fe), Fe‐bound organic matter, and nutrient concentrations were quantified to clarify the drivers of DOM quality (composition and biodegradability). The proportion of biodegradable DOM increased exponentially with decreasing initial DOM concentration due to larger fractions of depolymerized DOM that was rich in small‐molecular phenols and proteinaceous components. Unexpectedly, the composition of DOM was decoupled from that of SOM or MAOM, but significantly related to enzymatic properties. These results indicate that microbial metabolism exhibited a dominant role in DOM generation. As DOM concentration declined, increased soil oxygen availability regulated DOM composition and enhanced its biodegradability mainly through mediating microbial metabolism and Fe oxidation. The oxygen‐induced oxidation of Fe(II) to Fe(III) removed complex DOM compounds with large molecular weight. Moreover, increased oxygen availability stimulated oxidase‐catalyzed depolymerization of aromatic substances, and promoted production of protein‐like DOM components due to lower enzymatic C/N acquisition ratio. As global changes in temperature and moisture will have large impacts on soil oxygen availability, the role of oxygen in regulating DOM dynamics highlights the importance of integrating soil oxygen supply with microbial metabolism and Fe redox status to improve model predictions of soil carbon under climate change. [ABSTRACT FROM AUTHOR]

Background: Traditional endoscopic submucosal dissection (ESD) has developed different methods, such as pocket method (P-ESD), traction-assisted method (T-ESD), and hybrid method (H-ESD). In this meta-analysis, the benefits and drawbacks of different ESD methods were discussed and ranked. Study Design: Studies comparing different methods of colorectal ESD were searched by using PubMed, EMBASE, and Cochrane Library databases. The study was conducted for five endpoints: en bloc resection rate, R0 resection rate, operation time, dissection speed, and adverse events rate. Pairwise and network meta-analyses were performed through Rev Man 5.4 and Stata 16.0. The quality of all included studies was assessed using the Cochrane Risk of Bias Tool and the Newcastle-Ottawa Scale. Results: Twenty-six studies met the inclusion criteria, including 7 RCTs and 19 non-RCTs, with a total of 3,002 patients. The pooled analysis showed that the en bloc resection rate of H-ESD was significantly lower than that of C-ESD, P-ESD, and T-ESD (RR = 0.28, 95% CI [0.12, 0.65]; RR = 0.11, 95% CI [0.03, 0.44]; RR = 8.28, 95% CI [2.50, 27.42]). Compared with C-ESD, the operation time of H-ESD and T-ESD was significantly shorter (MD = −21.83, 95% CI [−34.76, −8.90]; MD = −23.8, 95% CI [−32.55, −15.06]). Meanwhile, the operation time of T-ESD was also significantly shorter than that of P-ESD (MD = −18.74, 95% CI [−31.93, −5.54]). The dissection speed of T-ESD was significantly faster than that of C-ESD (MD = 6.26, 95% CI [2.29, 10.23]). Conclusion: P-ESD and T-ESD are probably the two best methods of colorectal ESD at present. The advantages of P-ESD are high en bloc resection rate and low incidence of adverse events. The advantages of T-ESD are rapid dissection and short operation time. [ABSTRACT FROM AUTHOR]

This paper aims to better predict highly skewed auto insurance claims by combining candidate predictions. We analyze a version of the Kangaroo Auto Insurance company data and study the effects of combining different methods using five measures of prediction accuracy. The results show the following. First, when there is an outstanding (in terms of Gini Index) prediction among the candidates, the "forecast combination puzzle" phenomenon disappears. The simple average method performs much worse than the more sophisticated model combination methods, indicating that combining different methods could help us avoid performance degradation. Second, the choice of the prediction accuracy measure is crucial in defining the best candidate prediction for "low frequency and high severity" (LFHS) data. For example, mean square error (MSE) does not distinguish well between model combination methods, as the values are close. Third, the performances of different model combination methods can differ drastically. We propose using a new model combination method, named ARM-Tweedie, for such LFHS data; it benefits from an optimal rate of convergence and exhibits a desirable performance in several measures for the Kangaroo data. Fourth, overall, model combination methods improve the prediction accuracy for auto insurance claim costs. In particular, Adaptive Regression by Mixing (ARM), ARM-Tweedie, and constrained Linear Regression can improve forecast performance when there are only weak learners or when no dominant learner exists. [ABSTRACT FROM AUTHOR]

Association of organic carbon (C) with iron (Fe) minerals is one important mechanism for long‐term terrestrial C storage. Yet, specific edaphic variables that directly contribute to Fe‐associated C across diverse soil types are still unclear. Through analyzing soils from the National Ecological Observatory Network (NEON) and other published data, here we show that soil pH primarily controls Fe‐associated C across the globe. Fe‐associated C in most soils ranged from 0 to 20 g kg−1 soil, with a strong increase from pH 4.2 to 3.5, but a small change in soils with pH > 4.2. A microcosm experiment further showed that raising soil pH by liming reduced the formation of Fe‐associated C in an acidic Oxisol. Together, these findings demonstrate the dominant role of soil pH in controlling the abundance of Fe‐associated C. Key Points: Soil pH, rather than reactive iron content, is a primary control on concentration of iron‐associated carbon at the global scaleNeither soil orders nor vegetation types have significant relationships with concentration of iron‐associated carbonIron‐associated carbon represents a relatively small fraction of total soil organic carbon globally [ABSTRACT FROM AUTHOR]

Oxygen (O2) limitation contributes to persistence of large carbon (C) stocks in saturated soils. However, many soils experience spatiotemporal O2 fluctuations impacted by climate and land‐use change, and O2‐mediated climate feedbacks from soil greenhouse gas emissions remain poorly constrained. Current theory and models posit that anoxia uniformly suppresses carbon (C) decomposition. Here we show that periodic anoxia may sustain or even stimulate decomposition over weeks to months in two disparate soils by increasing turnover and/or size of fast‐cycling C pools relative to static oxic conditions, and by sustaining decomposition of reduced organic molecules. Cumulative C losses did not decrease consistently as cumulative O2 exposure decreased. After >1 year, soils anoxic for 75% of the time had similar C losses as the oxic control but nearly threefold greater climate impact on a CO2‐equivalent basis (20‐year timescale) due to high methane (CH4) emission. A mechanistic model incorporating current theory closely reproduced oxic control results but systematically underestimated C losses under O2 fluctuations. Using a model‐experiment integration (ModEx) approach, we found that models were improved by varying microbial maintenance respiration and the fraction of CH4 production in total C mineralization as a function of O2 availability. Consistent with thermodynamic expectations, the calibrated models predicted lower microbial C‐use efficiency with increasing anoxic duration in one soil; in the other soil, dynamic organo‐mineral interactions implied by our empirical data but not represented in the model may have obscured this relationship. In both soils, the updated model was better able to capture transient spikes in C mineralization that occurred following anoxic–oxic transitions, where decomposition from the fluctuating‐O2 treatments greatly exceeded the control. Overall, our data‐model comparison indicates that incorporating emergent biogeochemical properties of soil O2 variability will be critical for effectively modeling C‐climate feedbacks in humid ecosystems. [ABSTRACT FROM AUTHOR]

BACKGROUND: The brown planthopper (BPH), Nilaparvata lugens, is a serious insect pest of rice. Autophagy and its related gene ATG3 play multiple roles in insects. However, information about the functions of ATG3 in BPH (NlATG3) is unavailable, and its potential as a target for pest control remains unclear. RESULTS: RT‐qPCR results showed a relatively low expression of NlATG3 in 1st–4th‐instar nymphs, which increased through 9‐day‐old adults. The expression of NlATG3 increased continuously in 1‐day‐old through 5‐day‐old eggs, whereas it decreased thereafter. The mRNA level of NlATG3 was markedly higher in the ovary (1.16) and head (1.00) compared to the rest body parts of BPH adults. Injecting nymphs with dsNlATG3 at doses from 62.5 to 250 ng per insect had strong lethal effect upon them. For the 5th‐instar nymphs, all individuals died within 5 days after receiving the dsNlATG3, and importantly, no individual successfully molted. Transmission electron microscopy revealed the new cuticle of nymphs injected with dsNlATG3 became loose and curved, which is clearly different from that of the control. Correspondingly, the obvious vesicles in epidermal cells disappeared after dsNlATG3‐treatment. RNAi of NlATG3 significantly reduced the total number of eggs laid per female as well as the eggs' hatchability, especially in the dsNlATG3♀ × dsGFP♂ group, whose total number of eggs laid per female largely decreased by 80.4%, and whose eggs' hatchability was significantly reduced from 95.7% to zero, when compared with the control (dsGFP♀ × dsGFP♂). CONCLUSION: NlATG3 is a promising target for developing RNAi‐based insect management strategies. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) form symbiosis with most terrestrial plant roots, obtaining photosynthates in return for mineral nutrients. Ecological theories based on the economics of trading partnership predict that nutrient enrichment would suppress AMF. Experimental results from nitrogen (N) and phosphorus (P) additions, however, were highly variable, and the underlying mechanisms remain unclear. Here we show distinct AMF responses to soil N:P stoichiometry manipulations via gradients of long‐term N and P additions in a Mongolian steppe. A complementary experiment with an acid addition gradient was designed to help tease apart the effect of N‐induced acidification from N nutrient. AMF root colonization and extraradical fungal biomass progressively decreased along the P gradient under two distinct host plant species, suggesting a carbon (C)‐P tradeoff. In contrast, low to moderate N inputs increased both AMF parameters, corresponding to the increasing N:P ratio. Yet, high N inputs reduced AMF colonization and biomass, and the magnitudes of N‐led inhibition were similar to those under acid additions that induced comparable changes in soil pH. Structural equation modeling further showed that while soil N:P stoichiometry primarily controlled the effect of P addition on AMF, N‐induced soil acidity overtook the N:P stoichiometry under high N inputs and dominated the effects of reactive N on AMF. In addition, AMF community composition in roots was more dependent on host plants and unresponsive to changes in soil nutrients. We further proposed a comprehensive framework that integrates biological and geochemical effects of reactive N and P inputs on AMF. Together, these results indicate that while the C‐P tradeoff controls P suppression of AMF, N‐induced acidification dominates the N inhibition. Our findings suggest that incorporation of geochemical impacts of N and P inputs would facilitate modeling efforts to project mycorrhizal impact on plant interactions and soil C balance under future nutrient enrichment scenarios. [ABSTRACT FROM AUTHOR]

The ongoing global change is multi‐faceted, but the interactive effects of multiple drivers on the persistence of soil carbon (C) are poorly understood. We examined the effects of warming, reactive nitrogen (N) inputs (12 g N m−2 year−1) and altered precipitation (+ or − 30% ambient) on soil aggregates and mineral‐associated C in a 4 year manipulation experiment with a semi‐arid grassland on China's Loess Plateau. Our results showed that in the absence of N inputs, precipitation additions significantly enhanced soil aggregation and promoted the coupling between aggregation and both soil fungal biomass and exchangeable Mg2+. However, N inputs negated the promotional effects of increased precipitation, mainly through suppressing fungal growth and altering soil pH and clay‐Mg2+‐OC bridging. Warming increased C content in the mineral‐associated fraction, likely by increasing inputs of root‐derived C, and reducing turnover of existing mineral‐associated C due to suppression of fungal growth and soil respiration. Together, our results provide new insights into the potential mechanisms through which multiple global change factors control soil C persistence in arid and semi‐arid grasslands. These findings suggest that the interactive effects among global change factors should be incorporated to predict the soil C dynamics under future global change scenarios. [ABSTRACT FROM AUTHOR]

Oxygen (O2) limitation is generally understood to suppress oil carbon (C) decomposition and is a key mechanism impacting terrestrial C stocks under global change. Yet, O2 limitation may differentially impact kinetic or thermodynamic versus physicochemical C protection mechanisms, challenging our understanding of how soil C may respond to climate‐mediated changes in O2 dynamics. Although O2 limitation may suppress decomposition of new litter C inputs, release of physicochemically protected C due to iron (Fe) reduction could potentially sustain soil C losses. To test this trade‐off, we incubated two disparate upland soils that experience periodic O2 limitation—a tropical rainforest Oxisol and a temperate cropland Mollisol—with added litter under either aerobic (control) or anaerobic conditions for 1 year. Anoxia suppressed total C loss by 27% in the Oxisol and by 41% in the Mollisol relative to the control, mainly due to the decrease in litter‐C decomposition. However, anoxia sustained or even increased decomposition of native soil‐C (11.0% vs. 12.4% in the control for the Oxisol and 12.5% vs. 5.3% in the control for the Mollisol, in terms of initial soil C mass), and it stimulated losses of metal‐ or mineral‐associated C. Solid‐state 13C nuclear magnetic resonance spectroscopy demonstrated that anaerobic conditions decreased protein‐derived C but increased lignin‐ and carbohydrate‐C relative to the control. Our results indicate a trade‐off between physicochemical and kinetic/thermodynamic C protection mechanisms under anaerobic conditions, whereby decreased decomposition of litter C was compensated by more extensive loss of mineral‐associated soil C in both soils. This challenges the common assumption that anoxia inherently protects soil C and illustrates the vulnerability of mineral‐associated C under anaerobic events characteristic of a warmer and wetter future climate. [ABSTRACT FROM AUTHOR]

Autophagy plays multiple roles in regulating various physiological processes in cells. However, we currently lack a systematic analysis of autophagy and the autophagy-related gene 1 ATG1 in the brown planthopper (BPH, Nilaparvata lugens), one of the most destructive of the insect pests of rice. In this study, the full-length cDNA of an autophagy-related gene, NlATG1 , was cloned from BPH. Real-time qPCR (RT-qPCR) revealed that this NlATG1 gene was expressed differently across developmental stages, at higher levels in nymphs but lower levels in adults. RNA interference with dsNlATG1 significantly decreased the mRNA level of the target gene to 14.6% at day 4 compared with that of the dsGFP control group. The survival of the dsNlATG1-treated group decreased significantly from day 4 onward, dropping to 48.3% on day 8. Examination using transmission electron microscopy (TEM) showed that epithelial cells of the BPH's midgut in the dsNlATG1-treated group had less autophagic vacuoles than did the dsGFP control, and knockdown of NlATG1 clearly inhibited the starvation-induced autophagy response in this insect. RNA interference of NlATG1 upregulated the NlFis1 gene involved in mitochondrial fission, leading to reductions in mitochondrial width and area. Furthermore, knockdown of NlATG1 also decreased the ATP content and accumulation of glycogen. Together, these results demonstrate that the NlATG1 gene participates in regulating autophagy and fission of mitochondria in the brown planthopper, making it a potentially promising target for pest control given its key role in autophagy, including maintaining the normal structure and function of mitochondria. [ABSTRACT FROM AUTHOR]

Removal of biomass for bioenergy production may decrease soil organic carbon. While perennials or cover‐cropped grains often have greater root production than annual grain crops, they variably impact soil carbon and underlying mechanisms remain unclear. We used high‐frequency measurements of soil respiration and natural abundance carbon stable isotopes to differentiate respiration sources, pool sizes, and decomposition rate constants during a 10 month incubation of soils collected to 1 m depth from a 10 year old field experiment in Iowa, United States. Conversion of corn–soybean rotations to reconstructed prairies or addition of a rye cover crop to continuous corn significantly altered respiration sources and dynamics of fast‐ and slow‐cycling carbon (turnover times of weeks to months–years, respectively), but had little effect on bulk soil carbon and several extractable pools (except in fertilized prairie). Both unfertilized and fertilized prairies increased slow‐cycling carbon pools relative to annual crops, but only in 0–25 cm soil. Compared with fertilized prairie, the unfertilized prairie significantly increased decomposition rates of fast‐ and slow‐cycling carbon pools in 0–25 cm soil, likely explaining the lack of significant bulk soil carbon accrual despite twofold greater root production. Carbon derived from C4 plants decomposed faster than C3‐derived carbon across all depths and cropping systems and contributions of C3‐carbon to respiration increased with depth. Respiration of cover crop‐derived carbon was greatest in 0–25 cm soil but comprised >25% of respiration below 25 cm, implying a disproportionate impact of the cover crop on deep soil metabolism. However, the cover crop also increased the decomposition rates of fast‐ and slow‐cycling carbon pools and decreased their pool sizes across all depths relative to corn without a cover crop. Despite their notable environmental benefits, neither unfertilized perennials nor cover crops necessarily promote rapid soil carbon sequestration relative to conventional annual bioenergy systems because of concomitant increases in decomposition. [ABSTRACT FROM AUTHOR]

High-dimensional linear regression with interaction effects is broadly applied in research fields such as bioinformatics and social science. In this paper, first, we investigate the minimax rate of convergence for regression estimation in high-dimensional sparse linear models with two-way interactions. Here, we derive matching upper and lower bounds under three types of heredity conditions: strong heredity, weak heredity, and no heredity. From the results: 1) A stronger heredity condition may or may not drastically improve the minimax rate of convergence. In fact, in some situations, the minimax rates of convergence are the same under all three heredity conditions; 2) The minimax rate of convergence is determined by the maximum of the total price of estimating the main effects and that of estimating the interaction effects, which goes beyond purely comparing the order of the number of non-zero main effects $r_{1}$ and non-zero interaction effects $r_{2}$ ; and 3) Under any of the three heredity conditions, the estimation of the interaction terms may be the dominant part in determining the rate of convergence. This is due to either the dominant number of interaction effects over main effects or the higher interaction estimation price induced by a large ambient dimension. Second, we construct an adaptive estimator that achieves the minimax rate of convergence regardless of the true heredity condition and the sparsity indices $r_{1}, r_{2}$. [ABSTRACT FROM AUTHOR]

The Loess Plateau soil in northwest China originated from wind sediments and is characterized by deep soil profiles and large organic carbon (C) content. Severe soil erosion constantly exposes deep soils to the surface, making the organic C vulnerable to microbial decomposition. Few, however, have so far examined how soil microbial activity and community composition in the deep loess soil respond to perturbations. We examined microbial responses in three layers of a clay‐loam loess (topsoil, 0–20 cm; midsoil, 40–60 cm; subsoil, 80–100 cm) to substrate additions (0.8 g glucose‐C kg−1 soil) under two temperature regimes (25 and 35°C). Soil C:N ratio was significantly larger in the subsoil (20.3) than topsoil (7.4). Glucose addition significantly increased CO2 efflux during a 30‐day incubation period and the relative magnitude of the increase was four times larger in the subsoil than topsoil. The temperature sensitivity (Q10) of soil CO2 efflux increased significantly with soil depth in the absence of glucose addition (i.e., ambient soil), but it decreased under glucose addition. Also, glucose addition significantly increased phenol oxidase and peroxidase activities in the subsoil, which might contribute to the stimulation of microbial CO2 efflux. Composition of the microbial community was more affected by temperature increase in the topsoil, but more responsive to labile C addition in the subsoil. Together, these results indicated that the composition of soil communities and microbial activities in the topsoil and deep soil responded differently to warming and labile C input. Our findings suggest that organic C in deep loess soils can be highly sensitive to environmental changes, emphasizing the need for more long‐term monitoring and quantitative assessment of organic C release from this important C pool. Highlights: Microbial responses to labile C and warming were examined along a Loess Plateau soil profile.Microbial respiration was more responsive to C addition and warming in deep soil than topsoil.Microbial composition and activity were sensitive to temperature in the topsoil but to labile C in the subsoil.Climate change may facilitate CO2 efflux from deep Loess Plateau soils. [ABSTRACT FROM AUTHOR]

Abstract: Impacts of reactive nitrogen (N) inputs on ecosystem carbon (C) dynamics are highly variable, and the underlying mechanisms remain unclear. Here, we proposed a new conceptual framework that integrates plant, microbial and geochemical mechanisms to reconcile diverse and contrasting impacts of N on soil C. This framework was tested using long‐term N enrichment and acid addition experiments in a Mongolian steppe grassland. Distinct mechanisms could explain effects of N on particulate and mineral‐associated soil C pools, potentially explaining discrepancies among previous N addition studies. While plant production predominated particulate C changes, N‐induced soil acidification strongly affected mineral‐associated C through decreased microbial growth and pH‐sensitive associations between iron and aluminium minerals and C. Our findings suggest that effects of N‐induced acidification on microbial respiration and geochemical properties should be included in Earth system models that predict ecosystem C budgets under future N deposition/input scenarios. [ABSTRACT FROM AUTHOR]

Purpose: Obstructive sleep apnea (OSA) has been associated with changes in brain structure and regional function in certain brain areas. However, the functional features of network organization in the whole brain remain largely uncertain. The purpose of this study was to identify the OSA-related spatial centrality distribution of the whole brain functional network and to investigate the potential altered intrinsic functional hubs. Methods: Forty male patients with newly confirmed severe OSA on polysomnography, and well-matched good sleepers, participated in this study. All participants underwent a resting-state functional MRI scan and clinical and cognitive evaluation. Voxel-wise degree centrality (DC) was measured across the whole brain, and group difference in DC was compared. The relationship between the abnormal DC value and clinical variables was assessed using a linear correlation analysis. Results: Remarkably similar spatial distributions of the functional hubs (high DC) were found in both groups. However, OSA patients exhibited a pattern of significantly reduced regional DC in the left middle occipital gyrus, posterior cingulate cortex, left superior frontal gyrus, and bilateral inferior parietal lobule, and DC was increased in the right orbital frontal cortex, bilateral cerebellum posterior lobes, and bilateral lentiform nucleus, including the putamen, extending to the hippocampus, and the inferior temporal gyrus, which overlapped with the functional hubs. Furthermore, a linear correlation analysis revealed that the DC value in the posterior cingulate cortex and left superior frontal gyrus were positively correlated with Montreal cognitive assessment scores, The DC value in the left middle occipital gyrus and bilateral inferior parietal lobule were negatively correlated with apnea-hypopnea index and arousal index in OSA patients. Conclusion: Our findings suggest that OSA patients exhibited specific abnormal intrinsic functional hubs including relatively reduced and increased DC. This expands our understanding of the functional characteristics of OSA, which may provide new insights into understanding the dysfunction and pathophysiology of OSA patients. [ABSTRACT FROM AUTHOR]

In the present study, KNO3 and tea saponin (TS) were applied to investigate systematically the potential impact of their concentrations on dissipation of anerobic polycyclic aromatic hydrocarbons (PAH) in paddy soils. After 150 days of incubation, the highest removals for total, 3-, 4-, and 5(+6)-ring PAHs were 84.3, 92.3, 85.6, and 69.3%, respectively, with the simultaneous application of 50 mM KNO3 and 2% TS, w/w. Moreover, using response surface methodology, the theoretical maximum removal for total PAHs in the 80-100% range can be achieved at >35 mM KNO3 and >1.5% TS, w/w. Meanwhile, Tenax® TA extraction and a first-three-compartment model method demonstrated that TS (w/w, 2%) could serve as an effective bioaccessibility-enhancing agent to increase the rapidly and slowly desorbing fractions of PAHs from 6 and 12% in the control to 29 and 42% ( p < 0.05), respectively. In addition, proper concentrations of KNO3 and TS in soil could enhance soil microbial characteristics, including denitrifying bacterial count, nitrate reductase activity, and soil microbial biomass carbon and nitrogen, suggesting at least the partial restoration of microbial biological function to the soil after remediation. The results are important in understanding the anerobic PAH dissipation in paddy soils. [ABSTRACT FROM AUTHOR]

The central region of the hypermineralized dolphin's bulla (ear bone), contains >95 wt% mineral with ~10 wt% structurally incorporated carbonate. The mineral-bioapatite undergoes phase changes during heating. However, the step-by-step changes with increasing temperature are still unclear. Raman spectroscopy is proved to be a powerful technique in analyzing crystallographic transformation of bioapatite. The bulla was heated stepwise from 100 °C to 900 °C for the Raman analyses. Both positions and widths of Raman peaks were studied. Crystals of the bioapatite are stable up to 200 °C. From 300 °C to 600 °C, the decrystallization is a gradual process with delicate changes rather than a sharp transformation. Carbonate is depleted at ~500 °C, and then decrystallization is terminated. At temperature over 600 °C, bioapatite re-crystallizes and is transformed to OHAp at 700 °C. The crystallinity is then gradually improved while the temperature increased to 900 °C. No phases of β-tricalcium phosphate or calcium pyrophosphate were detected in this study. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bacteria serve as live food and nutrients for bacterial-feeding nematodes (BFNs) in soils, and influence nematodes behavior and physiology through their metabolism. Five bacterial taxa (Bacillus amyloliquefaciens JX1, Variovorax sp. JX14, Bacillus megaterium JX15, Pseudomonas fluorescens Y1 and Escherichia coli OP50) and the typical BFN Caenorhabditis elegans were selected to study the effects of bacterial respiration and growth rates on the feeding preferences, brood size and lifespan of nematodes. P. fluorescens Y1 and E. coli OP50 were found to be more active, with high respiration and rapid growth, whereas B. amyloliquefaciens JX1 and B. megaterium JX15 were inactive. The nematode C. elegans preferred active P. fluorescens Y1 and E. coli OP50 obviously. Furthermore, worms that fed on these two active bacteria produced more offspring but had shorter lifespan, while inactive and less preferred bacteria had increased nematodes lifespan and decreased the brood size. Based on these results, we propose that the bacterial activity may influence the behavior and life traits of C. elegans in the following ways: (1) active bacteria reproduce rapidly and emit high levels of CO2 attracting C. elegans; (2) these active bacteria use more resources in the nematodes’ gut to sustain their survival and reproduction, thereby reducing the worm's lifespan; (3) inactive bacteria may provide less food for worms than active bacteria, thus increasing nematodes lifespan but decreasing their fertility. Nematodes generally require a balance between their preferred foods and beneficial foods, only preferred food may not be beneficial for nematodes. [ABSTRACT FROM AUTHOR]

Soil acidification caused by acid deposition and N fertilization can significantly affect the composition and activity of microbial communities in acidic soils. However, whether and how acidification affects soil microorganisms and microbial‐mediated carbon (C) dynamics in alkaline soils are less known. Based on a 7‐year (2016–2023) acid addition experiment in an alkaline grassland (pH > 8) on the Loess Plateau in Northwest China, we examined the effects of soil acidification on soil fungal and bacterial communities and their C metabolism. Unexpectedly, our results showed that soil acidification mainly reduced fungal diversity, rather than bacterial diversity, possibly because acidification led to soil NH4+ accumulation and decreased plant diversity. Also, soil acidification reduced forb but increased grass biomass, and enhanced root production and turnover rate. Laboratory incubation experiments showed that changes in the microbial community and soil properties jointly promoted microbial decomposition of soil organic C (SOC), with more promotion for the decomposition of labile C (i.e. glucose) (+68.4%) than recalcitrant C (i.e. tannin) (+29.1%). Synthesis. Soil acidification reduced fungal diversity and stimulated SOC decomposition in an alkaline grassland. Given that pH decline can also accelerate soil inorganic C dissolution and carbonate‐derived CO2 release, these results highlight that soil acidification can exacerbate C loss in the alkaline soils over the long term. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]