In situ densification and heparin immobilization of bacterial cellulose vascular patch for potential vascular applications.

Nowadays, developing vascular grafts (e.g., vascular patches and tubular grafts) is challenging. Bacterial cellulose (BC) with 3D fibrous network has been widely investigated for vascular applications. In this work, different from BC vascular patch cultured with the routine culture medium, dopamine (DA)-containing culture medium is employed to in situ synthesize dense BC fibrous structure with significantly increased fiber diameter and density. Simultaneously, BC fibers are modified by DA during in situ synthesis process. Then DA on BC fibers can self-polymerize into polydopamine (PDA) accompanied with the removal of bacteria in NaOH solution, obtaining PDA-modified dense BC (PDBC) vascular patch. Heparin (Hep) is subsequently covalently immobilized on PDBC fibers to form Hep-immobilized PDBC (Hep@PDBC) vascular patch. The obtained results indicate that Hep@PDBC vascular patch exhibits remarkable tensile and burst strength due to its dense fibrous structure. More importantly, compared with BC and PDBC vascular patches, Hep@PDBC vascular patch not only displays reduced platelet adhesion and improved anticoagulation activity, but also promotes the proliferation, adhesion, spreading, and protein expression of human umbilical vein endothelial cells, contributing to the endothelialization process. The combined strategy of in situ densification and Hep immobilization provides a feasible guidance for the construction of BC-based vascular patches.

The moderating role of work environment in the relationship between proactive personality and personal growth initiative among nurses: a cross-sectional study.

BACKGROUNDS: Personal growth initiative (PGI) is regarded as a meaningful concept with potential value at both the individual and organizational levels, but little is known about the factors that contribute to nurses' PGI. This study aimed to explore how proactive personality and hospital work environment affect PGI of clinical nurses. METHODS: A cross-sectional study was conducted between September and October 2022 among 4414 nurses from 10 tertiary general hospitals in 10 cities in Sichuan, China, using a two-stage sampling method. Self-reported anonymous online questionnaires, such as sociodemographic information survey, personal growth initiative scale II, the 10-item proactive personality scale, and practice environment scale-nursing work index were used to collect data. Multiple hierarchical regression analyses were performed to examine research hypotheses. RESULTS: Among the control variables in this study, nurses' self-perceptions of general health status and professional title positively predicted PGI (ß = 0.462, 95%CI = 0.272-0.653; ß = 1.078, 95%CI = 0.508-1.648). After adding control variables, both proactive personality (ß = 1.143, 95%CI = 1.096-1.190) and work environment (ß = 3.391, 95%CI = 2.904-3.879) positively predicted PGI. The work environment positively moderated the association between proactive personality and PGI (ß = 0.108, 95%CI = 0.025-0.191). These predictors jointly explained 50.3% of the variance in PGI. CONCLUSIONS: Nurses with a greater tendency to have a typical proactive personality have higher levels of personal growth initiative, and this positive effect will be better highlighted in a healthier work environment. Nursing managers should prioritize the employment of people with proactive personality traits, focus on the development and stimulation of proactive personality traits in nurses, and establish a supportive work environment to maximize the personal growth initiative of nurses.

Serum HER2 Level Predicts Therapeutic Efficacy and Prognosis in Advanced Breast Cancer Patients.

Background: The purpose of this study was to investigate the therapeutic efficacy and prognosis of serum HER2 (sHER2) in patients with advanced breast cancer. Methods: We analyzed the sHER2 levels of 200 patients with advanced breast cancer receiving first or second line treatment, the tissue HER2 (tHER2) level was also analyzed. Indicators of therapeutic efficacy and prognosis were objective response rate (ORR), disease control rate (DCR), and time to progression (TTP). Results: The baseline sHER2 level was high in 132 patients and low in 68 patients. The high level of sHER2 is correlated with molecular subtype (p=0.016), visceral metastasis (p<0.001), liver metastasis (p<0.001), tissue HER-2 (tHER2) (p=0.001), and, among tHER2-low tumors (59 patients), the baseline sHER2 high level was associated with a higher proportion of brain metastasis. The ORR of patients with baseline sHER2 high level is higher than those with baseline sHER2 low level (p=0.026). The TTP of patients with baseline sHER2 low level is longer than the patients with baseline sHER2 high level (p=0.024). For patients with baseline sHER2 high level, a significant decrease in sHER2 after two cycles of treatment indicates higher ORR, DCR, and an extension of TTP. After multiple cycles of treatment, for patients with tHER-2 positive and baseline sHER2 high level, the DCR in the sHER2 decrease in the negative group was higher than that in the continuous positive group (p=0.037). Patients with a rapid decline type of sHER2 dynamic change curve had higher ORR and prolonged TTP compared with patients with other types of sHER2 dynamic change curve. There is no correlation between OS and sHER2 levels. Conclusion: Our study showed that patients with advanced breast cancer had a high level of sHER2 at recurrence, regardless of whether they are tHER2 positive or negative. Dynamic detection of sHER2 can help predict therapeutic efficacy and prognosis, regardless of whether tHER-2 is positive or negative.

Lung microdialysis and in vivo PK/PD integration of cefquinome against Actinobacillus pleuropneumoniae in a porcine experimental lung infection model.

This study aim to explore the application of microdialysis in pharmacokinetic (PK) and pharmacodynamic (PD) integration of cefquinome against Actinobacillus pleuropneumoniae in a porcine experimental lung infection model. The model was established via intratracheal inoculation where average bacterial counts (CFU) in the lungs of infected pigs reached 6.57 log10 CFU/g after 3 h. The PK profiles of unbound cefquinome in lung dialysates were determined following intramuscular injection of single doses of 0.125, 0.25, 0.5, 1, 2, and 4 mg/kg. Lung dialysate samples were collected using microdialysis at a flow rate of 1.5 µL/min until 24 h. The PD studies were conducted over 24 h based on 10 intermittent dosing regimens and total daily doses ranged from 0.25 to 4 mg/kg and dosage intervals included 12 and 24 h. The lung tissue was collected after 24 h of treatment and homogenized for bacterial counts. The relationships between PK/PD parameters derived from lung dialysates and drug efficacy were analyzed using an inhibitory sigmoid Emax model. The percentage of time the free drug concentration exceeded the minimum inhibitory concentration (%fT > MIC) was the PK/PD index best describing the antimicrobial activity (R2 = 0.96) in the porcine experimental infection model. The %fT > MIC values required to achieve net bacterial stasis, 1, 2 and 3 log10 CFU/g reductions in the lung were 22.45, 28.86, 37.62, and 56.46%, respectively. Cefquinome exhibited time-dependent characteristics against A. pleuropneumoniae in vivo. These results provide valuable insights into the application of microdialysis in PK/PD integration model studies and optima regimen of cefquinome for the treatment of porcine respiratory diseases caused by A. pleuropneumoniae.

Characteristics and antioxidant activities of seed oil from okra (Abelmoschus esculentus L.).

To investigate the potential functional properties and added value of okra seed oil and provide a scientific basis for further industrial development and production of okra seed oil, its fatty acid profile, total phenolic, fat-soluble vitamin composition, mineral element composition, and antioxidant activities were examined in this study. Also, correlations between bioactive components and the antioxidant activities of okra seed oil were explored. The study results show that okra seed oil contains 12 types of fatty acids, 65.22% of which are unsaturated acids, and among these unsaturated acids, linoleic acid (43%) and oleic acid (20.16%) are two dominant acid types. Compared with walnut oil and peanut oil, okra seed oil contains relatively high total phenols, fat-soluble vitamins, and a variety of essential mineral nutrients, with a total phenolic content (TPC) of 959.65 µg/mL, a total tocopherol content of 742.71 µg/mL, a vitamin A content of 0.0017 µg/100 mL, a vitamin D content of 1.44 µg/100 mL, and a vitamin K1 content of 52.54 ng/100 mg. Also, okra seed oil exhibits better scavenging activities on hydroxyl (IC50 = 0.50 mg/mL) and ammonium salt (ABTS) free radicals (IC50 = 6.46 mg/mL) and certain reducing power (IC50 = 17.22 mg/mL) at the same concentration. The scavenging activities of okra seed oil on hydroxyl radicals and ABTS radicals, as well as its reducing power, are significantly correlated with its contents of total phenol, total tocopherol, α-tocopherol, and γ-tocopherol (p < .01). These results show that okra seed oil is rich in bioactive substances, thus presenting great nutritional potential.

Efficient and Robust Parameter Optimization of the Unitary Coupled-Cluster Ansatz.

The variational quantum eigensolver (VQE) framework has been instrumental in advancing near-term quantum algorithms. However, parameter optimization remains a significant bottleneck for VQE, requiring a large number of measurements for successful algorithm execution. In this paper, we propose sequential optimization with approximate parabola (SOAP) as an efficient and robust optimizer specifically designed for parameter optimization of the unitary coupled-cluster ansatz on quantum computers. SOAP leverages sequential optimization and approximates the energy landscape as quadratic functions, minimizing the number of energy evaluations required to optimize each parameter. To capture parameter correlations, SOAP incorporates the average direction from previous iterations into the optimization direction set. Numerical benchmark studies on molecular systems demonstrate that SOAP achieves significantly faster convergence and greater robustness to noise compared with traditional optimization methods. Furthermore, numerical simulations of up to 20 qubits reveal that SOAP scales well with the number of parameters in the ansatz. The exceptional performance of SOAP is further validated through experiments on a superconducting quantum computer using a 2-qubit model system.

BRCC3 Regulation of ALK2 in Vascular Smooth Muscle Cells: Implication in Pulmonary Hypertension.

BACKGROUND: An imbalance of antiproliferative BMP (bone morphogenetic protein) signaling and proliferative TGF-ß (transforming growth factor-ß) signaling is implicated in the development of pulmonary arterial hypertension (PAH). The posttranslational modification (eg, phosphorylation and ubiquitination) of TGF-ß family receptors, including BMPR2 (bone morphogenetic protein type 2 receptor)/ALK2 (activin receptor-like kinase-2) and TGF-ßR2/R1, and receptor-regulated (R) Smads significantly affects their activity and thus regulates the target cell fate. BRCC3 modifies the activity and stability of its substrate proteins through K63-dependent deubiquitination. By modulating the posttranslational modifications of the BMP/TGF-ß-PPARγ pathway, BRCC3 may play a role in pulmonary vascular remodeling, hence the pathogenesis of PAH. METHODS: Bioinformatic analyses were used to explore the mechanism of BRCC3 deubiquitinates ALK2. Cultured pulmonary artery smooth muscle cells (PASMCs), mouse models, and specimens from patients with idiopathic PAH were used to investigate the rebalance between BMP and TGF-ß signaling in regulating ALK2 phosphorylation and ubiquitination in the context of pulmonary hypertension. RESULTS: BRCC3 was significantly downregulated in PASMCs from patients with PAH and animals with experimental pulmonary hypertension. BRCC3, by de-ubiquitinating ALK2 at Lys-472 and Lys-475, activated receptor-regulated Smad1/5/9 (Smad1/5/9), which resulted in transcriptional activation of BMP-regulated PPARγ, p53, and Id1. Overexpression of BRCC3 also attenuated TGF-ß signaling by downregulating TGF-ß expression and inhibiting phosphorylation of Smad3. Experiments in vitro indicated that overexpression of BRCC3 or the de-ubiquitin-mimetic ALK2-K472/475R attenuated PASMC proliferation and migration and enhanced PASMC apoptosis. In SM22α-BRCC3-Tg mice, pulmonary hypertension was ameliorated because of activation of the ALK2-Smad1/5-PPARγ axis in PASMCs. In contrast, Brcc3-/- mice showed increased susceptibility of experimental pulmonary hypertension because of inhibition of the ALK2-Smad1/5 signaling. CONCLUSIONS: These results suggest a pivotal role of BRCC3 in sustaining pulmonary vascular homeostasis by maintaining the integrity of the BMP signaling (ie, the ALK2-Smad1/5-PPARγ axis) while suppressing TGF-ß signaling in PASMCs. Such rebalance of BMP/TGF-ß pathways is translationally important for PAH alleviation.

A Nature-Derived, Hetero-Structured, Pro-Healing Bioadhesive Patch for High-Performance Sealing of Wet Tissues.

Tissue adhesives are promising alternatives to sutures and staples to achieve wound closure and hemostasis. However, they often do not work well on tissues that are soaked in blood or other biological fluids, and organs that are typically exposed to a variety of harsh environments such as different pH values, nonhomogeneous distortions, continuous expansions and contractions, or high pressures. In this study, a nature-derived multilayered hetero-bioadhesive patch (skin secretion of Andrias davidianus (SSAD)-Patch) based on hydrophilic/hydrophobic pro-healing bioadhesives derived from the SSAD is developed, which is designed to form pressure-triggered strong adhesion with wet tissues. The SSAD-Patch is successfully applied for the sealing and healing of tissue defects within 10 s in diverse extreme injury scenarios in vivo including rat stomach perforation, small intestine perforation, fetal membrane defect, porcine carotid artery incision, and lung lobe laceration. The findings reveal a promising new type of self-adhesive regenerative SSAD-Patch, which is potentially adaptable to broad applications (under different pH values and air or liquid pressures) in sutureless wound sealing and healing.

Single-Electron Reduction of "Push-Pull" C-C Single Bond and Decyanation Using Tertiary Amines as the Organic Electron Donor.

Using commercially available tertiary amines as an organic electron donor (OED), the reduction of "push-pull" C-C single bond and reductive decyanation of tetrahydroisoquinolines were realized. These reactions exhibited higher reaction efficiency and better functional group tolerance compared with those of metallic reductants, and the mechanistic study indicated that a radical intermediate was involved in the reduction of the C-C single bond, which provides a new way to the OED-enabled mild reduction.

Endothelium-specific SIRT7 targeting ameliorates pulmonary hypertension through Krüpple-like factor 4 deacetylation.

AIMS: Pulmonary hypertension (PH) is a pulmonary vascular disease characterized by a high mortality rate. Pulmonary arterial endothelium cells (PAECs) serve as a primary sensor of various environmental cues, such as shear stress and hypoxia, but PAEC dysfunction may trigger vascular remodelling during the onset of PH. This study aimed to illustrate the role of Sirtuin 7 (SIRT7) in endothelial dysfunction during PH and explore the potential therapeutic strategy for PH. METHODS AND RESULTS: SIRT7 levels were measured in human and murine experimental PH samples. Bioinformatic analysis, immunoprecipitation, and deacetylation assay were used to identify the association between SIRT7 and Krüpple-like factor 4 (KLF4), a key transcription factor essential for endothelial cell (EC) homeostasis. Sugen5416 + hypoxia (SuHx)-induced PH mouse models and cell cultures were used for the study of the therapeutic effect of SIRT7 for PH. SIRT7 level was significantly reduced in lung tissues and PAECs from PH patients and the SuHx-induced PH mouse model as compared with healthy controls. Pulmonary endothelium-specific depletion of Sirt7 increased right ventricular systolic pressure and exacerbated right ventricular hypertrophy in the SuHx-induced PH model. At the molecular level, we identified KLF4 as a downstream target of SIRT7, which deacetylated KLF4 at K228 and inhibited the ubiquitination-proteasome degradation. Thus, the SIRT7/KLF4 axis maintained PAEC homeostasis by regulating proliferation, migration, and tube formation. PAEC dysfunction was reversed by adeno-associated virus type 1 vector-mediated endothelial overexpression of Sirt7 or supplementation with nicotinamide adenine dinucleotide (NAD)+ intermediate nicotinamide riboside which activated Sirt7; both approaches successfully reversed PH phenotypes. CONCLUSION: The SIRT7/KLF4 axis ensures PAEC homeostasis, and pulmonary endothelium-specific SIRT7 targeting might constitute a PH therapeutic strategy.

CBr4 as a Mild Oxidant-Enabled Oxidation of a sp3 C-H Bond: A Facile Synthesis of the Persistent Iminium Salts of Tetrahydroisoquinolines.

Using CBr4 as a mild oxidant, the direct C-H bond oxidation of N-aryltetrahydroisoquinolines was achieved, giving a series of the corresponding iminium salts in high yields under metal- and photo-free reaction conditions. This reaction is superior in high yields and good functional group tolerance, and the late-stage derivatization showed that these iminium salts can readily be applied to the synthesis of the functionalized THIQs.

Genetic evaluation for twin pregnancies using karyotyping and single nucleotide polymorphism array analysis.

The study aimed to assess chromosomal abnormalities in twin pregnancies using karyotyping and SNP array analysis. The research involved 530 twin pregnancies from two prenatal diagnosis centers between October 2012 and October 2022. Two types of twin pregnancies were considered: monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA), with a total of 177 MCDA and 353 DCDA cases. Chromosomal abnormalities were examined based on chorionic and amniotic sac properties and clinical indications. Among 42 twin pregnancies, 50 fetuses showed chromosomal abnormalities by karyotyping, with 35 cases of aneuploidy in DCDA and 10 in MCDA. Trisomy 21 was the most common aberration, affecting 15 fetuses in DCDA and 4 in MCDA. The rate of discordant karyotypes in MCDA and DCDA groups was 1.1% and 8.8%, respectively. Ultrasound abnormalities and advanced maternal age were frequent indications (55.3% and 39.2%, respectively). Aneuploidy frequencies in DCDA and MCDA pregnancies with advanced maternal age were 10.6% and 4.5%. Cardiac defects and increased nuchal translucency were common anomalies, with higher incidences of chromosomal abnormalities in DCDA (12.5% and 6.9%) and MCDA groups (23.5% and 3.7%). SNP array identified 1.6% clinically significant copy number variants in DCDA fetuses with ultrasound abnormalities, while no significant CNVs were found in MCDA pregnancies. Chromosomal aneuploidies were the primary abnormalities in twin pregnancies, with detectable abnormalities and clinically significant CNVs more likely in DCDA pregnancies, especially those with ultrasound abnormalities.

Oxidants Controlled C-H Bond Functionalization of N-Aryltetrahydroisoquinolines: The Construction of the Quaternary Carbon Center and Cleavage of the C-N Bond.

Initiated by triarylamine radical cation salt (TBPA), the direct C-H bond functionalization of α-N-aryltetrahydroisoquinoline esters was smoothly realized, giving a series of α-hydroxylated derivatives with a quaternary carbon center in good yields. Differently, in the presence of tert-butyl nitrite (TBN), the C-N single bond was cleaved to keto esters. The mechanistic study revealed that these reactions were mediated by a similar mechanism, in which the N-nitrosation might provide a driving force to the C-N bond cleavage.

Enhanced the treatment of ischemic stroke through intranasal temperature-sensitive hydrogels of edaravone and borneol inclusion complex.

Since ischemic stroke occurs by a combination of multiple mechanisms, therapies that modulate multiple mechanisms are required for its treatment. The combination of edaravone (EDA) and borneol can significantly ameliorate the symptoms of neurological deficits in cerebral ischemia-reperfusion model in rats. In this study, the solubility of borneol and edaravone was improved by hydroxypropyl-ß-cyclodextrin and PEG400. Furthermore, a nasal temperature-sensitive hydrogel containing both edaravone and borneol inclusion complex (EDA-BP TSGS) was developed to overcome the obstacles of ischemic stroke treatment including the obstruction of the blood-brain barrier (BBB) and the unavailability and untimely of intravenous injection. The effectiveness of the thermosensitive hydrogel was investigated in transient middle cerebral artery occlusion/reperfusion model rats (MCAO/R). The results showed that EDA-BP TSGS could significantly alleviate the symptoms of neurological deficits and decrease the cerebral infarct area and the degree of brain damage. In summary, nasal EDA-BP TSGS is a secure and effective brain-targeting formulation that may provide a viable option for the clinical prophylaxis and treatment of ischemic stroke.

Size Segregation of Gold Nanoparticles into Bilayer-like Vesicular Assembly.

Size segregation of nanoparticles with different sizes into highly ordered, unique nanostructures is important for their practical applications. Herein, we demonstrate spontaneous self-assembly of the binary mixtures of small and large gold nanoparticles (GNPs; 5/15, 5/20, or 10/20 in diameter) in the presence of a tetra(ethylene glycol)-terminated octafluoro-4,4'-biphenol ligand, namely, TeOFBL, resulting in a size-segregated assembly. The outer single layer of large GNPs forming a gold nanoparticle vesicle (GNV) encapsulated the inner vesicle-like assembly composed of small GNPs, which is referred to as bilayer-like GNV and similar to the molecular bilayer structure of a liposome. The size segregation was driven by the solvophobic feature of the TeOFBLs on the surface of GNPs. A time-course study indicated that size segregation occurred instantaneously during the mixing stage of the self-organization process. The size-segregated precursors quickly fused with each other through the inner-inner and outer-outer layer fashion to form the bilayer-like GNV. This study provides a new approach to creating biomimetic bilayer capsules with different physical properties for potential applications such as surface-enhanced Raman scattering and drug delivery.

An analysis of the influencing factors of depression in older adults under the home care model.

Objectives: To explore and analyze the influencing factors of depression in older adults living at home, so as to propose suggestions for improving the quality of older adults living at home. Methods: We conducted a cross-sectional study on 498 older adults living at home based on questionnaire survey on the general information, daily living ability, health status, and care perception (including self-care, care for cohabitants, and care for non-cohabitants) of older adults living at home, as well as their willingness to help each other, and analyzed the influencing factors of depression among older adults living at home. Results: The results showed a willingness to help older adults, self-care, and total activities of daily living (ADL), health status was an influential factor for depression in older adults (p < 0.05). Conclusion: It aims to take targeted measures, such as encouraging older adults at home to actively participate in mutual assistance activities for older adults and care for themselves, so as to prevent and reduce the occurrence of depression in older adults.

Prenatal diagnosis and genetic etiology analysis of talipes equinovarus by chromosomal microarray analysis.

BACKGROUND: With the advancement of molecular technology, fetal talipes equinovarus (TE) is believed to be not only associated with chromosome aneuploidy, but also related to chromosomal microdeletion and microduplication. The study aimed to explore the molecular etiology of fetal TE and provide more information for the clinical screening and genetic counseling of TE by Chromosomal Microarray Analysis (CMA). METHODS: This retrospectively study included 131 fetuses with TE identified by ultrasonography. Conventional karyotyping and SNP array analysis were performed for all the subjects. They were divided into isolated TE group (n = 55) and complex group (n = 76) according to structural anomalies. RESULTS: Among the total of 131 fetuses, karyotype analysis found 12(9.2%) abnormal results, while SNP array found 27 (20.6%) cases. Trisomy 18 was detected most frequently among abnormal karyotypes. The detection rate of SNP array was significantly higher than that of traditional chromosome karyotype analysis (P < 0.05). SNP array detected 15 (11.5%) cases of submicroscopic abnormalities that karyotype analysis did not find. The most common CNV was the 22q11.2 microdeletion. For both analyses, the overall detection rates were significantly higher in the complex TE group than in the isolated TE group (karyotype: P < 0.05; SNP array: P < 0.05). The incremental yield of chromosomal abnormalities in fetuses with unilateral TE (22.0%) was higher than in fetuses with bilateral TE (19.8%), but this difference was not statistically significant (P > 0.05). Abnormal chromosomes were most frequently detected in fetuses with TE plus cardiovascular system abnormalities. CONCLUSION: Fetal TE is related to chromosomal microdeletion or microduplication. Prenatal diagnosis is recommended for fetuses with TE, and CMA testing is preferred. CMA can improve the detection rate of chromosomal abnormalities associated with fetal TE, especially in pregnancies with complex TE.

Factors associated with the perceived need for assistance from voluntary services in home-based older adults in Chinese urban areas: a cross-sectional study.

BACKGROUND: With China's rapidly aging population, meeting the diverse care needs of senior citizens is becoming more challenging. Although voluntary social services have numerous advantages and are popular among older adults, there is little information on the need for assistance from volunteer-based social services, particularly those with a medical background, and influencing factors among urban home-based older adults. This study aimed to assess the need for assistance from voluntary services and related factors among urban home-based older adults in China. METHODS: A cross-sectional study was conducted in 2022 on communities in four cities in China. The 27-item Home-Based Older Adults Assistance Need Scale was used to measure the assistance needs of 498 participants aged 60 and above. Multiple linear regression models were conducted to identify salient variables associated with the need for assistance from voluntary services. RESULTS: The mean score of the need for assistance from voluntary services was 88.60 ± 24.37. The mean scores of the items examining four dimensions, namely, health maintenance, visiting communication, social intercourse, and daily life, were 3.64 ± 1.08, 3.49 ± 1.04, 3.33 ± 1.08, and 2.78 ± 1.08, respectively. The level of depression, willingness to assist older adults, attaching importance to health preservation, ability to self-comfort, desire to accept assistance from others, and the presence of more children or none at all were all positively correlated with the perceived need for assistance from voluntary services. In contrast, social care obtained from visiting medical institutions was negatively correlated. These seven factors explained 28.5% of the total variance. CONCLUSIONS: Urban home-based older adults in China were found to have significant requirements for assistance from volunteer services, and several complex factors were associated with more significant assistance needs. These findings may encourage the extremely limited numbers of social volunteers, particularly those with a medical background, to identify priorities in providing assistance services to the large numbers of urban home-based older adults and thus improve service delivery.

Nitrogen addition stimulates N2O emissions via changes in denitrification community composition in a subtropical nitrogen-rich forest.

Microbially driven nitrification and denitrification play important roles in regulating soil N availability and N2O emissions. However, how the composition of nitrifying and denitrifying prokaryotic communities respond to long-term N additions and regulate soil N2O emissions in subtropical forests remains unclear. Seven years of field experiment which included three N treatments (+0, +50, +150 kg N ha-1 yr-1; CK, LN, HN) was conducted in a subtropical forest. Soil available nutrients, N2O emissions, net N mineralization, denitrification potential and enzyme activities, and the composition and diversity of nitrifying and denitrifying communities were measured. Soil N2O emissions from the LN and HN treatments increased by 42.37% and 243.32%, respectively, as compared to the CK. Nitrogen addition significantly inhibited nitrification (N mineralization) and significantly increased denitrification potentials and enzymes. Nitrification and denitrification abundances (except nirK) were significantly lower in the HN, than CK treatment and were not significantly correlated with N2O emissions. Nitrogen addition significantly increased nirK abundance while maintaining the positive effects of denitrification and N2O emissions to N deposition, challenging the conventional wisdom that long-term N addition reduces N2O emissions by inhibiting microbial growth. Structural equation modeling showed that the composition, diversity, and abundance of nirS- and nirK-type denitrifying prokaryotic communities had direct effects on N2O emissions. Mechanistic investigations have revealed that denitrifier keystone taxa transitioned from N2O-reducing (complete denitrification) to N2O-producing (incomplete denitrification) with increasing N addition, increasing structural complexity and diversity of the denitrifier co-occurrence network. These results significantly advance current understanding of the relationship between denitrifying community composition and N2O emissions, and highlight the importance of incorporating denitrifying community dynamics and soil environmental factors together in models to accurately predict key ecosystem processes under global change.