Newcomers building social capital by proactive networking: A signaling perspective.

Social networks can aid newcomers' learning and adjustment and facilitate their performance. However, knowledge about how newcomers build their social networks from the ground up is limited. Extending the socialization literature, we propose a model delineating newcomer proactive networking as the driver of advice ties with peer newcomers, which in turn influence newcomer reputation among higher status organizational insiders. Drawing on signaling theory, we propose that future-oriented newcomers are more likely to engage in proactive networking behaviors, a form of signaling that could help those newcomers build a larger number of peer advice ties. Such initial success may then transmit newcomers' signals to the managerial ranks, affording them a better reputation among managers. In addition, signaling theory suggests that the centrality of a newcomer's immediate supervisor in the managerial advice network can amplify the effect of the newcomer's own signaling actions (i.e., proactive networking behaviors) on their relationships with peers. We tested our hypotheses in two field survey studies. Study 1 found that newcomers higher in future orientation engaged in more proactive networking. Proactive networking helped newcomers form more peer advice ties, which were, in turn, positively related to their reputation among managers. Study 2 found that the supervisor's centrality in the managerial advice network moderated the relationship between newcomer proactive networking and peer advice ties. We discuss the implications of our findings for the newcomer adjustment and signaling theory literatures as well as for socialization practices. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Unpacking the effects of socialization programs on newcomer retention: A meta-analytic review of field experiments.

Decades of research conducted using field experiments and quasi-experiments have enabled us to accumulate causal evidence on the effectiveness of onboarding and socialization programs (SPs) across various contexts including employment, higher education, and military services. However, the literature is devoid of an integrated conceptual framework and a quantitative review evaluating the effect of such SPs on reducing newcomer turnover and its boundary conditions. In this study, we draw from a configurational approach to categorize strategic components of SPs, propose bundles of these components based on extant theories in the socialization literature, and examine the moderating effects of these bundles on the retention benefits of SPs. Combining 168 effect sizes from 83 field experiments, our meta-analysis reveals a significant overall effect size of OR = 1.46, suggesting that, on average, the odds of retention are 1.46 times higher for newcomers participating in a SP compared to newcomers in the control group. Our results also indicate that SPs' beneficial effects on newcomer retention are greater when they include the components of identifying effective task behaviors, encouraging proactivity, and facilitating social integration, a bundle aimed at satisfying key psychological needs identified by self-determination theory. We further demonstrate that the retention benefits associated with SP participation increase when the SPs are delivered in-person and in a staggered mode but remain intact across different sample types and study design features. We conclude by discussing how our study expands and develops theoretical understanding within the socialization literature and offers practical implications for managing newcomer retention that go beyond our current knowledge. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Spatial coupling coordination and interactive response between green finance and green total factor productivity: geographical analysis based on Chinese provinces, 2010-2020.

Based on the panel data of 30 provinces in China from 2010 to 2020, this study uses the coupling coordination degree model (CCDM), spatial autocorrelation analysis, and the panel vector autoregression (PVAR) model to quantitatively examine the dynamic coordination and interactive response of green finance (GF) and green total factor productivity (GTFP). The results show that the coupling coordination degree (CCD) between GF and GTFP during the study period shows an overall increasing trend and significant regional differentiation and remains at the medium level, indicating large room for improvement. The CCDs of provinces fluctuate between the low and high types. The distribution gradually shifts from a "high in the south and low in the north" pattern to a "high in the east and low in the west" configuration. The spatial difference of coupling development continues to expand and presents a significant spatial positive correlation. In addition, GF and GTFP in China exhibit significant self-reinforcing characteristics, but the reinforcing effect gradually decreases. There is only a unidirectional interaction relationship between GF and GTFP, which is GF actively fosters the advancement of GTFP, while the influence of GTFP on GF appears less pronounced. This research provides comprehensive insights into the dynamic interaction between GF and GTFP.

Regional differences, dynamic evolution, and spatial-temporal convergence of green finance development level in China.

Green finance has great potential for supporting environmental improvement, combating climate change, and the economical and efficient use of resources. In this study, based on the panel data of 30 provinces in China from 2010 to 2020, we used the weighted TOPSIS model to measure the green finance development level (GFDL) in China and its three major regions. The Dagum's Gini coefficient, kernel density estimation, Markov chain, and the convergence model are used to analyze the regional differences, dynamic evolution, and spatial-temporal convergence of GFDL in China. The results show that, in general, the GFDL shows an upward trend, but the GFDL in various regions is unbalanced, which is characterized by the spatial distribution of "high in the southeast and low in the northwest" and "high in the coast and low in the inland". The overall difference of GFDL is showing an expanding trend, which is mainly caused by inter-regional difference. The absolute differences of GFDL between the overall country, the eastern region, and the western region are on a widening trend, while that in the central region is on a narrowing trend. In addition, the GFDLs between the overall country, the eastern region, and the western region have no significant σ convergence, while there is an obvious σ convergence trend in the central region. Further, the GFDLs in China and its three major regions have obvious absolute ß convergence trends and conditional ß convergence trends.

Preparation of chitosan-iron oxide modified sludge-based biochar for effective removal of tetracycline from water: performance and mechanism.

The release of antibiotics has attracted wide attention due to their abuse and discharge. How to remove these emerging contaminants is an urgent need to be solved. In the present study, sludge-based biochar combining chitosan and iron oxide was prepared via municipal sewage sludge. The novel biochar modified with chitosan and iron oxide exhibited satisfying performance in eliminating antibiotics from water. The application of modified biochar combined with activated persulfate (PS) showed a remarkable removal efficiency of 96.98% for tetracycline (TC). Analysis of the surface characteristics of the modified biochar showed the presence of structural defects, dispersed iron oxides, abundant functional groups, a porous structure, and a relatively stable crystal structure. These characteristics attributed significant importance to facilitating the degradation of TC. A series of experimental conditions including preparation temperature (600-900 ℃), reaction temperature (15-45 ℃), contaminant concentration (30-180 mg/L), adsorbent usage (0.1-1 g/L), pH (2-10), and persulfate addition concentration (1-5 mmol) were conducted. The results revealed that the highest removal efficiency was achieved at 96.98% under the conditions of TC concentration at 30 mg/L, reaction temperature at 35 ℃, pH of 4, adsorbent addition amount of 0.6 g/L, and PS concentration of 2 mmol, respectively. Three degradation pathways and seven intermediate products of TC were proposed. Therefore, our study provides a promising approach for developing effective removal of antibiotic pollutants.

Behavior change versus stability during the college-to-work transition: Life course and the "stickiness" of alcohol misuse at career entry.

To what extent and under what conditions do college graduates disengage from employment-incompatible behaviors during the college-to-work transition? Drawing from the life course perspective, we proposed a model highlighting considerable stability of employment-incompatible behaviors during initial months of organizational socialization. Our model predicted that maturing out of such behaviors, which is expected by employers and beneficial to career adjustment, would be more likely to occur given a conducive transition context. Using a large dataset tracking graduates from their last semester in college to up to approximately 1.5 years after graduation and with alcohol use as our empirical referent, we demonstrated that a pattern of high-risk drinking behavior may remain even after the transition into full-time employment. We further showed that lower levels of perceived cohort drinking norms and higher levels of mentoring were associated with a higher probability of maturing out, manifesting in a transition from a high-risk drinking profile before graduation to a moderate drinking profile after starting full-time employment. Finally, we found that maturing out was associated with lagged outcomes including lower levels of sleep problems and depression and fewer work days lost to absenteeism, thus underscoring the consequential nature of behavior profile shifts during the college-to-work transition.

Surface modification significantly changed the effects of nano-polystyrene on sediment microbial communities and nitrogen metabolism.

Nanoplastics are ubiquitous in the natural environment, and their ecological risks have received considerable attention. Surface modification is common for nanoplastics and an essential factor affecting their toxicity. However, studies on the potential effects of nanoplastics and their surface-modified forms on functional communities in aquatic systems are still scarce. This study investigated the effects of nano-polystyrene (nPS), amino-modified nPS (nPS-NH2), and carboxylated nPS (nPS-COOH) particles on sediment bacterial and fungal communities and their functions over a 60-day incubation period. The results showed that the fungal community was significantly inhibited by nPS-NH2 exposure, while the bacterial community diversity remained relatively stable in all nPS treatments. Proteobacteria and Ascomycota were the dominant phyla for the bacterial and fungal communities, respectively. Nitrification was inhibited in all nPS treatments, while denitrification was enhanced for nPS-NH2 and nPS-COOH treatments. The activity of four key denitrification enzymes (NAR, NIR, NOR, and NOS) was also significantly improved by nPS, resulting in increased nitrogen and nitrous oxide gas production, and decreased nitrate concentrations in the overlying water. This showed the total increased effect of nPS on the activity of denitrifiers. Our results suggest that surface modification significantly affects the effects of nPS on microbial communities and functions. The potential impacts of nPS on ecological functions should be elucidated with more attention.

Long-term effects of Ag NPs on denitrification in sediment: Importance of Ag NPs exposure ways in aquatic ecosystems.

The widespread use of silver nanoparticles (Ag NPs) inevitably leads to their increasing release into aquatic systems, with studies indicating that the mode of Ag NPs entry into water significantly affects their toxicity and ecological risks. However, there is a lack of research on the impact of different exposure ways of Ag NPs on functional bacteria in sediment. This study investigates the long-term influence of Ag NPs on denitrification process in sediments by comparing denitrifies responses to single (pulse injection of 10 mg/L) and repetitive (1 mg/L × 10 times) Ag NPs treatments over 60-day incubation. Results showed that a single exposure of 10 mg/L Ag NPs caused an obvious toxicity on activity and abundance of denitrifying bacteria on the first 30 days, reflecting by the decreased NADH amount, ETS activity, NIR and NOS activity, and nirK gene copy number, which resulted in a significant decline of denitrification rate in sediments (from 0.59 to 0.64 to 0.41-0.47 µmol15N L-1 h-1). While inhibition was mitigated with time and denitrification process recovered to the normal at the end of the experiment, the accumulated nitrate generated in the system showed that the recovery of microbial function did not mean the restoration of aquatic ecosystem after pollution. Differently, the repetitive exposure of 1 mg/L Ag NPs exhibited the evident inhibition on metabolism, abundance, and function of denitrifiers on Day 60, due to the accumulated amount of Ag NPs with the increased dosing number, indicating that the accumulated toxicity on functional microorganic community of repetitive exposure in less toxic concentration. Our study highlights the importance of Ag NPs entry pathways into aquatic ecosystem on their ecological risks, which affected dynamic responses of microbial function to Ag NPs.

TLR7/8 agonist (R848) inhibit bovine X sperm motility via PI3K/GSK3α/ß and PI3K/NFκB pathways.

Sex-control technology have great economic value and is one of the hot topics in livestock research. To produce more milk, dairy farmers prefer female offspring. X/Y sperm separation is an effective method for offspring sex control. Currently, the major commercial production method for sperm separation is flow cytometry sorting in cattle. However, flow cytometry requires expensive equipment and long sorting times. So, a simple and inexpensive method for producing a higher number of dairy cows is required. In this study, R848 activates toll-like receptor 7/8 (TLR7/8), thereby separating X from Y sperm. The results showed TLR7/8 is expressed in the tail of X sperm. Immunofluorescence (IF) of testes, epididymis, and ejaculate shows that the number of TLR7+/8+ sperm cells is up to 50 %. Furthermore, TLR7/8 agonist (R848) affects mitochondrial function through the PI3K/GSK3α/ß/hexokinase and PI3K/NFκB/hexokinase signalling pathways, inhibiting X sperm motility, while the motility of Y-sperm remains unchanged. The difference in sperm motility causes Y sperm (with high motility) to move to the upper layer and X-sperm (with low motility) to the lower layer allowing the separation of X and Y sperm. Based on this study, we reveal a simple and effective method for enriched X/Y sperms from cattle.

Influence of the Maillard Reaction on Properties of Air-Assisted Electrospun Gelatin/Zein/Glucose Nanofibers.

To develop biodegradable, sustainable, and environment-friendly functional food-packaging materials, gelatin/zein/glucose nanofibers were fabricated through air-assisted electrospinning and then crosslinked by the Maillard reaction under mild conditions (60 °C and 50% relative humidity) in this study. Compared to traditional electrospinning, air-assisted electrospinning increased the yield of nanofibers by 10 times, and the average diameter from 263 nm to 664 nm, while the airflow facilitated uniform and smooth nanofiber formation. During the Maillard reaction in 0-5 days, the gelatin/zein/glucose showed no morphology change. Fourier transform infrared spectra analysis indicated that gelatin interacted with zein through hydrogen bonding and the occurrence of the Maillard reaction among the protein and glucose molecules. After four days of Maillard reaction, the nanofibers presented higher thermal stability, the most hydrophobic surface (water contact angle: 133.6°), and stiffer network structure (elastic modulus of 38.63 MPa, tensile strength of 0.85 MPa). Overall, Maillard-reaction-crosslinked gelatin/zein/glucose nanofibers showed favorable physical properties, which suggests their potential for application in food-active packaging.

Can the carbon metabolic activity of biofilm be regulated by the hydrodynamic conditions in urban rivers?

Hydrodynamic regulation is widely used to improve the water quality of urban rivers. However, it is yet to explore substantially whether hydrodynamics could regulate the metabolic activity of biofilm in such aquatic systems. Herein, the pilot experiment of hydrodynamics in the rotation tanks was designed, including two experiment phases, namely constant flow and adjusting flow for 21 days and 14 days, respectively. In constant flow phase, biofilms grew in five shear stress gradients (R1-R5, 0.0044- 0.12 Pa). The carbon metabolic rate (k) of mature biofilms evaluated by BIOLOG ECO microplates showed a hump-shaped relationship with increasing shear stress, with R3 (0.049 Pa) the highest, while R5 (0.12 Pa) the lowest. To verify whether the metabolic activity of biofilm cultured at constant flow phase can be regulated by shear stress, we initiated the adjusting flow phase, and shear stress in reactors was reset uniformly at 0.049 Pa (with the highest k). Results showed the carbon metabolic activity of biofilm in reactor R4 and R5 increased rapidly by day 3, and there was no significant difference between the carbon metabolic rates among the five treatments by day 14. Meanwhile, the utilization levels of polymers and carbohydrates by biofilms were significantly different among the five treatments after hydrodynamic regulations. These results suggested that the total carbon metabolic activity of biofilm can be regulated by hydrodynamics, while the divergent changes of the specific carbon source category might affect the biofilm-mediated carbon biogeochemical processes, which should be considered for the application of hydrodynamic regulation in river ecological restoration projects.

Polystyrene nanoplastics change the functional traits of biofilm communities in freshwater environment revealed by GeoChip 5.0.

There is an increasing concern regarding the potential effects of nanoplastics (NPs) on freshwater ecosystems. Considering the functional values of biofilms in freshwater, knowledge on whether and to what extent NPs can influence the ecosystem processes of biofilms were still limited. Herein, the freshwater biofilms cultured in lab were exposed to 100 nm polystyrene NPs (PS-NPs) of different dosages (1 and 10 mg/L) for 14 days. Confocal laser scanning microscope observation indicated that biofilms were dominated by filamentous, and spiral algae species and the intensity of extracellular polymeric substances increased under PS-NPs exposure. GeoChip 5.0 analysis revealed that PS-NPs exposure triggered a significant increase in functional genes α diversity (p < 0.05) and altered biofilms' functional structure. Furthermore, the abundance of genes involved in the total carbon and nitrogen cycling were increased under PS-NPs exposure. The abundance of nitrogen fixation genes experienced the most pronounced increase (24.4%) under 1 mg/L PS-NPs treatment, consistent with the increase of ammonium in overlying water. Whereas antibiotic resistance genes and those related to photosynthetic pigments production were suppressed. These results provided direct evidence for PS-NPs' effects on the biofilm functions in terms of biogeochemical cycling, improving our understanding of the potentials of NPs on freshwater ecosystems.

Biofilm influenced metal accumulation onto plastic debris in different freshwaters.

Microbial biofilms can rapidly colonize plastic debris in aquatic environments and subsequently, accumulate chemical pollutants from the surrounding water. Here, we studied the microbial colonization of different plastics, including polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene (PE) exposed in three freshwater systems (the Qinhuai River, the Niushoushan River, and Donghu Lake) for 44 days. We also assessed the biofilm mass and associated metals attached to plastics. The plastics debris characteristics, such as contact angle and surface roughness, greatly affected the increased biofilm biomass. All types of metal accumulation onto the plastic substrate abundances significantly higher than the concentrations of heavy metal in the water column, such as Ba (267.75 µg/g vs. 42.12 µg/L, Donhu Lake), Zn (254 µg/g vs. 0.023 µg/L the Qinhuai River), and Cr (93.75 µg/g vs. 0.039 µg/L, the Niushoushan River). Compared with other metals, the heavy metal Ba, Cr and Zn accumulated easily on the plastic debris (PET, PP, PVC, and PE) at all incubation sites. Aquatic environmental factors (total nitrogen, total phosphorus, and suspended solids concentrations) largely shaped metal accumulation onto plastic debris compared with plastic debris properties.

Job search self-regulation during COVID-19: Linking search constraints, health concerns, and invulnerability to job search processes and outcomes.

The COVID-19 pandemic has caused tremendous job loss and made it difficult for unemployed individuals to search for new jobs. Specifically, the pandemic has created numerous job search obstacles, such as increased childcare and community responsibilities, that interfere with job seekers' ability to search for a job. Yet, the job search literature has scantily examined the implications of such job search constraints for job seekers even in normal times, and the limited studies that do exist have produced mostly null findings. Drawing from self-regulation theories, we position COVID-19 job search constraints as a catalyst for lower hopeful search cognitions but greater reflective metacognitive activities. To account for the distinct mechanism via which health concerns highlighted by the pandemic influence job search, we further contend that job search self-regulation is contingent upon job seekers' COVID-19 invulnerability, a novel resource-protective cognition that reflects an optimistic perception regarding how at risk job seekers feel to catching and falling ill due to COVID-19. In turn, we link such self-regulatory cognition and effort to seekers' job search distress, and job search behaviors and outcomes (i.e., number of job interviews), respectively. We also identify health-related resource loss risk factors (i.e., health status and share of family and friends' COVID-19 exposure) that impact COVID-19 invulnerability perceptions. Collecting three waves of data from 228 unemployed job seekers, we found general support for our model. Theoretical and practical implications of the current research for now and after the pandemic are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Menthol Targeting AMPK Alleviates the Inflammatory Response of Bovine Mammary Epithelial Cells and Restores the Synthesis of Milk Fat and Milk Protein.

Mastitis is one of the most serious diseases that causes losses in the dairy industry, seriously impairing milk production and milk quality, and even affecting human health. Menthol is a cyclic monoterpene compound obtained from the stem and leaves of peppermint, which has a variety of biological activities, including anti-inflammatory and antioxidant activity. The purpose of this study was to investigate the preventive effect of menthol on the lipopolysaccharide-induced inflammatory response in primary bovine mammary gland epithelial cells (BMECs) and its anti-inflammatory mechanism. First, BMECs were isolated and amplified from the udders of Holstein cows by enzymatic hydrolysis. BMECs were treated with menthol (10, 50, 100, 200 µM) for 1h, followed by lipopolysaccharide (5µg/ml) for 12 h. Lipopolysaccharide treatment upregulated the protein levels of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (INOS) and the mRNA abundance of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-1ß (IL-1ß), while menthol was able to inhibit this effect. The inhibitory effect of menthol on proinflammatory factors was significantly reduced when autophagy was blocked using 3-Methyladenine (5µg/ml), an inhibitor of autophagy. Furthermore, lipopolysaccharide treatment reduced the expression levels of milk lipids and milk proteins, which were inhibited by menthol. In addition, menthol (200 µM) treatment was able to significantly upregulate the expression level of autophagy-related protein LC3B, downregulate the expression level of P62, promote the expression abundance of autophagy-related gene mRNA, and enhance significantly enhance autophagic flux. Interestingly, treatment of BMECs with menthol (200 µM) promoted the phosphorylation of AMP-activated protein kinase (AMPK) and unc-51 like kinase 1 (ULK1) and increased the nuclear localization of nuclear factor-E2 associated factor 2 (Nrf-2). When the AMPK pathway was blocked using compound C (10µg/ml), an inhibitor of AMPK, autophagy was significantly inhibited. Autophagy levels were significantly decreased after blocking the Nrf-2 pathway using ML385 (5µg/ml), an inhibitor of Nrf-2. Overall, the data suggest that menthol activates the AMPK-ULK1 pathway to initiate the onset of autophagy and maintains the level of autophagy through the AMPK-Nrf-2 pathway. In conclusion, the findings suggest that menthol may alleviate the inflammatory response in BMECs via the AMPK/ULK1/Nrf-2/autophagy pathway.

Distinct microbial metabolic activities of biofilms colonizing microplastics in three freshwater ecosystems.

Concerns are growing about the increasing amounts of microplastics (MPs) and their ecological impacts, especially the influences of "plastisphere" in the freshwater ecosystems. Although the microbial structure and composition of biofilms are investigated, knowledge of their microbial functions remains limited. Herein, we investigated the functional diversity of carbon metabolism in biofilms colonizing one inert (glass) and two MPs as polyvinyl chloride (PVC) and polyethylene terephthalate (PET) substrates incubated for 44 days in situ in the Niushoushan River, the Qinhuai River, and Donghu Lake. 2D confocal laser scanning microscopy images visualized distinct micro-structures and biofilm compositions on three substrates. BIOLOG ECO microplates indicated variation on carbon utilization capacities of biofilms of inert and MPs in three freshwater ecosystems. Biofilms on PET showed lower capacities and carbon metabolism rates than those on glass and PVC, indicating the presence of substrate-specific functional diversity. The Shannon-Wiener diversity, Simpson diversity and Shannon evenness indices for the Niushoushan River and Donghu Lake were ordered as glass > PVC > PET. Besides to MPs-specific factors, environmental factors including nutrient (i.e., TN and TP) and turbidity largely shaped biofilm carbon metabolism. Overall findings demonstrated that as specific niches, MPs influenced microbial-mediated carbon cycling in the freshwater ecosystems and MPs-promoted microbial communities posed ecological significance.

Effectiveness of stereotype threat interventions: A meta-analytic review.

This meta-analytic review examined the effectiveness of stereotype threat interventions (STIs). Integrating the identity engagement model (Cohen, Purdie-Vaughns, & Garcia, 2012) with the process model of stereotype threat (Schmader, Johns, & Forbes, 2008), we categorized STIs into 3 types: belief-based, identity-based, and resilience-based STIs. Combining 251 effect sizes from 181 experiments, we found an overall effect size of d = 0.44, with the intervention group outperforming the control group. Subgroup analyses showed that although all 3 types of STIs helped counter stereotype threat, primary-appraisal-based (i.e., belief-based and identity-based) STIs were more effective than secondary-appraisal-based (i.e., resilience-based) STIs. We also traced the theoretical roots of 11 specific intervention strategies and showed that 9 of them yielded significant effect sizes. Moreover, we found evidence of publication bias regarding some but not all intervention types. These findings' theoretical and practical implications, as well as methodological issues and future research directions for the STI literature, are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Effects of silver nanoparticles on coupled nitrification-denitrification in suspended sediments.

The effects of varying concentrations of Ag NPs on coupled nitrification and denitrification (CND) in two suspended sediments (SPSs) sizes were investigated using isotopic tracer method. In general, 0.5 and 5 mg/L Ag NPs had less effect on CND, while 2 and 10 mg/L Ag NPs exhibited the improvement and inhibition effect, respectively. The CND improvement by 2 mg/L NPs was mainly due to the enhanced nitrifying and denitrifying enzyme activity. However, 10 mg/L Ag NPs inhibited NH4+ oxidation by directly reducing the AMO activity and AOB abundance. The inhibition on NAR and NIR activity and their encoding narG and nirK gene abundance further inhibited NO3- and NO2- reduction, leading to a dramatic decrease in the 15N-N2 production. The above inhibition effects were attributed to the nano-effects of Ag NPs, which led to the excessive ROS amount and the decreased T-AOC level in microbial systems. But the connection between nitrification and denitrification was not broken after Ag NPs exposure. Moreover, the results indicated that N-cycling in clay and silt-type SPS systems could be more sensitive than sand-type SPS systems to NP exposure. The findings provide a basis for evaluating the environmental risks of Ag NPs in water-sediment systems.

Effects of Ag NPs on denitrification in suspended sediments via inhibiting microbial electron behaviors.

The wide use of silver nanoparticles (Ag NPs) inevitably leads to their increasing emission into aquatic environments. However, before their final deposition into sediments, the ecological effects of Ag NPs in suspended sediment (SPS) systems have not received much attention. Herein, we investigated the influences of Ag NPs on denitrification in SPS systems, and explored the potential toxicity mechanism through microbial metabolism (electron behaviors) and isotope tracing (added 15NO3-). After exposure to 10 mg/L Ag NPs, electron generation, transport and consumption during denitrification were clearly inhibited, which led to a decrease in the SPS denitrification rate. Specifically, the generation of NADH (electron donor) was significantly decreased to 59.92-86.47% with the Ag NPs treatments by affecting the degradation of glucose, one of the major reasons for the decreased denitrification. It also indicated that Ag NPs could affect nitrogen metabolism by influencing carbon metabolism. In addition, ETSA was clearly inhibited by the affected electron transfer and reception during denitrification; that was the most direct way in the microbial electron transport chain to affect the SPS denitrification rate. Furthermore, the particle size and concentration of SPS affected the toxicity of Ag NPs. The denitrification process in SPS systems with a smaller particle size and lower particle concentration was easily affected by Ag NPs, suggesting that SPS systems dominated by clay (particle size < 3.9 µm) or that less turbulence (having low SPS concentration) might be at greater risk factor when exposed to NPs. Thus, it is important to understand the risks of pollutants, such as Ag NPs, to biogeochemical cycles and ecosystem function in SPS systems.

Negative Self-perception of Aging and Mortality in Very Old Chinese Adults: The Mediation Role of Healthy Lifestyle.

OBJECTIVES: Previous literature has consistently shown a positive association between negative self-perception of aging and mortality in middle-aged and older adults. However, two questions remain unsolved: (a) whether such association holds among very old people (i.e., the fourth age) and (b) the potential mediators that could contribute to the positive association. This study sought to fill in the research gap by examining the association between self-perception of aging and mortality in a group of very old Chinese participants (i.e., aged over 78 years). METHODS: Four waves of data across a span of 8 years (2000-2008) were obtained from the Chinese Longitudinal Healthy Longevity Survey, which measured a total of 9,683 participants' negative self-perception of aging, survival status, cognitive functioning, diet, as well as other demographic information. RESULTS: Latent growth models with survival analysis were conducted, and the results replicated previous findings indicating an association between negative self-perceptions of aging and reduced survival. Moreover and more importantly, a potential mediator-healthy lifestyle (e.g., eating fresh vegetables and fruits, exercising regularly, and no smoking)-was identified, such that older adults with more negative self-perception of aging tended to engage in less healthy lifestyle, which could lead to increased risk of mortality. DISCUSSION: The findings provided support for a longitudinal behavioral pathway of health, linking negative perceptions of aging to mortality, and also yielded important practical implications for older adults to reach longevity.