Study on the outdoor thermal comfort of college students under different activity intensities in a high-altitude climate zone.

Introduction: Research on the outdoor thermal comfort (OTC) of a university campus is beneficial to the physical and mental health of college students. Methods: In this study, the OTC of students attending Tibet University in Lhasa, which experiences high-altitude cold climate conditions, under different activity intensities was studied using field measurements and a questionnaire survey. Results: With the increase in activity intensity, the comfort physiologically equivalent temperature (PET) value gradually increased in summer, while the comfortable PET value gradually decreased in winter. The most comfortable PET value is 17.6°C in summer and 11.5°C in winter. The neutral PET of Tibetan college students during outdoor activities in summer was 16.3°C, and the neutral PET of outdoor activities in winter was 12.1°C. Gender and ethnicity had different effects on thermal sensation under different activity intensities. Under vigorous-intensity activities, PET in winter and summer had the greatest influence on thermal sensation. The situation was different under moderate-intensity activity. PET had the greatest influence on thermal sensation in summer, and Tmrt had the greatest influence on thermal sensation in winter. Discussion: These findings provide a basis for an improved design of the outdoor environment under different outdoor activity intensities in high-altitude areas.

Proteomic characterization of hUC-MSC extracellular vesicles and evaluation of its therapeutic potential to treat Alzheimer's disease.

In recent years, human umbilical cord mesenchymal stem cell (hUC-MSC) extracellular vesicles (EVs) have been used as a cell replacement therapy and have been shown to effectively overcome some of the disadvantages of cell therapy. However, the specific mechanism of action of EVs is still unclear, and there is no appropriate system for characterizing the differences in the molecular active substances of EVs produced by cells in different physiological states. We used a data-independent acquisition (DIA) quantitative proteomics method to identify and quantify the protein composition of two generations EVs from three different donors and analysed the function and possible mechanism of action of the proteins in EVs of hUC-MSCs via bioinformatics. By comparative proteomic analysis, we characterized the different passages EVs. Furthermore, we found that adaptor-related protein complex 2 subunit alpha 1 (AP2A1) and adaptor-related protein complex 2 subunit beta 1 (AP2B1) in hUC-MSC-derived EVs may play a significant role in the treatment of Alzheimer's disease (AD) by regulating the synaptic vesicle cycle signalling pathway. Our work provides a direction for batch-to-batch quality control of hUC-MSC-derived EVs and their application in AD treatment.

Bioactive compound schaftoside from Clinacanthus nutans attenuates acute liver injury by inhibiting ferroptosis through activation the Nrf2/GPX4 pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Clinacanthus nutans (Burm. f.) Lindau, a traditional herb renowned for its anti-tumor, antioxidant, and anti-inflammatory properties, has garnered considerable attention. Although its hepatoprotective effects have been described, there is still limited knowledge of its treatment of acute liver injury (ALI), and its mechanisms remain unclear. AIM OF THE STUDY: To assess the efficacy of Clinacanthus nutans in ALI and to identify the most effective fractions and their underlying mechanism of action. METHODS: Bioinformatics was employed to explore the underlying anti-hepatic injury mechanisms and active compounds of Clinacanthus nutans. The binding ability of schaftoside, a potential active ingredient in Clinacanthus nutans, to the core target nuclear factor E2-related factor 2 (Nrf2) was further determined by molecular docking. The role of schaftoside in improving histological abnormalities in the liver was observed by H&E and Masson's staining in an ALI model induced by CCl4. Serum and liver biochemical parameters were measured using AST, ALT and hydroxyproline kits. An Fe2+ kit, transmission electron microscopy, western blotting, RT-qPCR, and DCFH-DA were used to measure whether schaftoside reduces ferroptosis-induced ALI. Subsequently, specific siRNA knockdown of Nrf2 in AML12 cells was performed to further elucidate the mechanism by which schaftoside attenuates ferroptosis-induced ALI. RESULTS: Bioinformatics analysis and molecular docking showed that schaftoside is the principal compound from Clinacanthus nutans. Schaftoside was shown to diminish oxidative stress levels, attenuate liver fibrosis, and forestall ferroptosis. Deeper investigations revealed that schaftoside amplified Nrf2 expression and triggered the Nrf2/GPX4 pathway, thereby reversing mitochondrial aberrations triggered by lipid peroxidation, GPX4 depletion, and ferroptosis. CONCLUSION: The lead compound schaftoside counters ferroptosis through the Nrf2/GPX4 axis, providing insights into a novel molecular mechanism for treating ALI, thereby presenting an innovative therapeutic strategy for ferroptosis-induced ALI.

Single-cell sequencing reveals the immune microenvironment landscape related to anti-PD-1 resistance in metastatic colorectal cancer with high microsatellite instability.

BACKGROUND: The objective response rate of microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC) patients with first-line anti-programmed cell death protein-1 (PD-1) monotherapy is only 40-45%. Single-cell RNA sequencing (scRNA-seq) enables unbiased analysis of the full variety of cells comprising the tumor microenvironment. Thus, we used scRNA-seq to assess differences among microenvironment components between therapy-resistant and therapy-sensitive groups in MSI-H/mismatch repair-deficient (dMMR) mCRC. Resistance-related cell types and genes identified by this analysis were subsequently verified in clinical samples and mouse models to further reveal the molecular mechanism of anti-PD-1 resistance in MSI-H or dMMR mCRC. METHODS: The response of primary and metastatic lesions to first-line anti-PD-1 monotherapy was evaluated by radiology. Cells from primary lesions of patients with MSI-H/dMMR mCRC were analyzed using scRNA-seq. To identify the marker genes in each cluster, distinct cell clusters were identified and subjected to subcluster analysis. Then, a protein‒protein interaction network was constructed to identify key genes. Immunohistochemistry and immunofluorescence were applied to verify key genes and cell marker molecules in clinical samples. Immunohistochemistry, quantitative real-time PCR, and western blotting were performed to examine the expression of IL-1ß and MMP9. Moreover, quantitative analysis and sorting of myeloid-derived suppressor cells (MDSCs) and CD8+ T cells were performed using flow cytometry. RESULTS: Tumor responses in 23 patients with MSI-H/dMMR mCRC were evaluated by radiology. The objective response rate was 43.48%, and the disease control rate was 69.57%. ScRNA-seq analysis showed that, compared with the treatment-resistant group, the treatment-sensitive group accumulated more CD8+ T cells. Experiments with both clinical samples and mice indicated that infiltration of IL-1ß-driven MDSCs and inactivation of CD8+ T cells contribute to anti-PD-1 resistance in MSI-H/dMMR CRC. CONCLUSIONS: CD8+ T cells and IL-1ß were identified as the cell type and gene, respectively, with the highest correlation with anti-PD-1 resistance. Infiltration of IL-1ß-driven MDSCs was a significant factor in anti-PD-1 resistance in CRC. IL-1ß antagonists are expected to be developed as a new treatment for anti-PD-1 inhibitor resistance.

Levels, distribution characteristics, and sources of heavy metals in indoor dust in Shijiazhuang, China.

Heavy metals in indoor dust are associated with health risks in humans. However, in Shijiazhuang, a city in northern China with severe haze, no research has been published on this topic. To determine the content, distribution characteristics, and sources of heavy metals in indoor dust in the city of Shijiazhuang, indoor dust samples from 33 sampling points in the main urban area of Shijiazhuang were collected and tested. Concentrations of Cu, Ni, Cr, Zn, Cd, and Pb were 87.0, 35.1, 104.4, 568.0, 1.980, and 187.6 mg·kg-1, respectively; their levels have been discussed statistically in comparison with the reported values in other cities in China. The sources of heavy metals were analyzed using enrichment factor, correlation coefficient, and principal component analysis. The results showed that the levels of all six elements in indoor dust in Shijiazhuang exceeded the background values of soil in Hebei Province. Among these, Cd, Pb, and Zn were significantly enriched. The enrichment factors of Cu, Ni, and Cr were below 10, and their levels at different sampling points were similar, indicating their geogenic source. The corresponding pollution levels of Cd, Pb, and Zn were relatively high, and their levels at different points were significantly different and correlated, indicating that they were derived mainly from transportation. Additionally, the level of Zn was significantly affected by the indoor environment. Our findings provide a basis for conducting health risk assessments in the future.

Stable Indium Tin Oxide with High Mobility.

Indium tin oxide (ITO) is widely used in a variety of optoelectronic devices, occupying a huge market share of $1.7 billion. However, traditional preparation methods such as magnetron sputtering limit the further development of ITO in terms of high preparation temperature (>350 °C) and low mobility (∼30 cm2 V-1 s-1). Herein, we develop an adjustable process to obtain high-mobility ITO with both appropriate conductivity and infrared transparency at room temperature by a reactive plasma deposition (RPD) system, which has many significant advantages including low-ion damage, low deposition temperature, large-area deposition, and high throughput. By optimizing the oxygen flow during the RPD process, ITO films with a high mobility of 62.1 cm2 V-1 s-1 and a high average transparency of 89.7% at 800-2500 nm are achieved. Furthermore, the deposited ITO films present a smooth surface with a small roughness of 0.3 nm. The stability of ITO films to heat, humidity, radiation, and alkali environments is also investigated with carrier mobility average changes of 19.3, 4.4, and 4.7%, showcasing strong environmental adaptability. We believe that stable ITO films with high mobility prepared by a low-damage deposition method will be widely used in full spectral optoelectronic applications, such as tandem solar cells, infrared photodetectors, light-emitting diodes, etc.

Dyadobacter diqingensis sp. nov., isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China.

A Gram-negative, aerobic, nonmotile, rod-shaped and yellow-pigment-producing bacteria was isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China and characterized using a polyphasic approach. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM B04101T was closely related to the type strain of Dyadobacter koreensis DSM 19938T (97.81%) and Dyadobacter frigoris AR-3-8T (97.95%). The predominant respiratory quinone was menaquinone-7 (MK-7). The major polar lipid was phosphatidylethanolamine. The major fatty acids were summed feature 3 (C16:1ω7c/C16:1ω6c), C18:1ω9c and C16:0. The DNA G + C content was 43.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain YIM B04101T belonged to a cluster comprising species of the genus Dyadobacter. However, it differed from its closest relative, Dyadobacter koreensis KCTC 12537T and Dyadobacter frigoris AR-3-8T, in many physiological properties. Based on these phenotypic characteristics and phylogenetic distinctiveness, strain YIM B04101T is considered to be a novel species of the genus Dyadobacter, for which the name Dyadobacter diqingensis sp. nov. is proposed. The type strain is YIM B04101T (= CGMCC 1.19249T = CCTCC AB 2021270).

Pressure-Induced Indirect-Direct Bandgap Transition of CsPbBr3 Single Crystal and Its Effect on Photoluminescence Quantum Yield.

Despite extensive study, the bandgap characteristics of lead halide perovskites are not well understood. Usually, these materials are considered as direct bandgap semiconductors, while their photoluminescence quantum yield (PLQY) is very low in the solid state or single crystal (SC) state. Some researchers have noted a weak indirect bandgap below the direct bandgap transition in these perovskites. Herein, application of pressure to a CsPbBr3 SC and first-principles calculations reveal that the nature of the bandgap becomes more direct at a relatively low pressure due to decreased dynamic Rashba splitting. This effect results in a dramatic PLQY improvement, improved more than 90 times, which overturns the traditional concept that the PLQY of lead halide perovskite SC cannot exceed 10%. Application of higher pressure transformed the CsPbBr3 SC into a pure indirect bandgap phase, which can be maintained at near-ambient pressure. It is thus proved that lead halide perovskites can induce a phase transition between direct and indirect bandgaps. In addition, distinct piezochromism is observed for a perovskite SC for the first time. This work provides a novel framework to understand the optoelectronic properties of these important materials.

Evaluation and Optimization Design for Microclimate Comfort of Traditional Village Squares Based on Extension Correlation Function.

The evaluation approaches for microclimate comfort in traditional villages often ignore the year-round impact and the impact from dynamic and static behaviors, as well as the composite impact of wind and heat environments. To solve the problem, this study presents an evaluation and optimization design strategy for microclimate comfort of traditional village squares based on extension correlation function, using field survey, computer simulation, and example analysis. Firstly, the wind and heat environments in the space of the square were measured on the site with an ultrasonic integrated weather station. Secondly, simulation parameters were configured on PHOENICS (computational fluid dynamics software), namely, boundary conditions, wind environment, heat environment, and green plants, and used to simulate the wind and heat environments in the space of the square, followed by a correlation analysis between the simulation results and the measured results. Finally, the extension correlation function was adopted to comprehensively evaluate the microclimate comfort of the preliminary design scheme, and the design scheme of the square was finalized through repeated adjustments. The proposed strategy was verified on an example: Xieduqi square, Zoumatang village, eastern China's Zhejiang Province. The example analysis shows that the proposed strategy is highly operable. The research effectively improves the optimization design of traditional village squares, extends the digital technology system of traditional villages, and greatly drives rural construction in the future.

Mixed Solvents Assisted Post-Treatment Enables High-Efficiency Single-Junction Perovskite and 4T Perovskite/CIGS Tandem Solar Cells.

The interface between the perovskite layer and the hole transport layer (HTL) plays a vital role in hole extraction and electron blocking in perovskite solar cells (PSCs), and it is particularly susceptible to harmful defects. Surface passivation is an effective strategy for addressing the above concerns. However, because of its strong polarity, isopropyl alcohol (IPA) is used as a solvent in all of the surface treatment materials reported thus far, and it frequently damages the surface of perovskite. In this paper, a method is proposed for dissolving the passivation materials, for example, guanidine bromide (GABr), in mixed solvents (1:1) of IPA and toluene (TL), which can efficiently passivate interface and grain boundary defects by minimizing the IPA solubility of the perovskite surface. As a result, all the performance parameters Voc, Jsc, and FF are improved, and the power conversion efficiency (PCE) increased from 20.1 to 22.7%. Moreover, combining the PSCs with GABr post-treatment in mixed solvents with copper indium gallium selenide (CIGS) solar cells, a 4-terminal (4T) perovskite/CIGS tandem device is realized and a PCE of 25.5% is achieved. The mixed solvent passivation strategy demonstrated here, hopefully, will open new avenues for improving PSCs' efficiency and stability.

A novel highly dispersed tetra-metal nano heterogeneous ozone catalyst derived from microbial adsorption and in situ pyrolysis.

In recent years, the pyrolysis of microbial biomasses that adsorb various metal ions has enabled the preparation of carbon-based polymetallic nanomaterials with excellent electrocatalytic and electrical energy storage properties. However, the preparation of ozone catalysts by this technique and the corresponding catalytic oxidation mechanism are still unclear. In this study, an Escherichia coli strain (BL21) was used for tetra-metal (Cu, Fe, Mn and Al) absorption and the obtained microbial biomass was pyrolyzed under the protection of a nitrogen flow at 700 °C and activated at 900 °C to prepare a microbial-char-based tetra-metal ozone catalyst (MCOC). This was used to degrade phenol and coking wastewater and exhibited a strong catalytic capability for coking wastewater, whose chemical oxygen demand removal efficiency of 70.86% is 16.7% higher than that of pure ozone and 14.67%, 7.21% and 3.58% higher than that of three commercial catalysts, respectively. It also improved the efficiency of ozonation for phenol by 33%. The MCOC was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive spectroscopy, transmission electron microscopy and other methods. The results demonstrated that the spherical metal nanoparticles had sizes ranging from 3 nm to 7 nm and that crystals of Fe2O3 and Fe3P were observed. The study showed that the MCOC promoted the production of more hydroxyl radicals and superoxides from ozone, which attack organics. The oxygen vacancies of the catalyst were also investigated. It was proved that the Lewis acid sites on the surface of metal oxides are the active centers of ozone decomposition. Therefore, this work provides a new method for the synthesis of multi-metal nanocomposites and expands the application of biosynthetic nanomaterials.

A longitudinal study reveals the alterations of the Microtus fortis colonic microbiota during the natural resistance to Schistosoma japonicum infection.

The gut microbiota has been demonstrated to associate with protection against helminth infection and mediate via microbial effects on the host humoral immunity. As a non-permissive host of Schistosoma japonicum, the Microtus fortis provides an ideal animal model to be investigated, because of its natural self-healing capability. Although researches on the systemic immunological responses have revealed that the host immune system contributes a lot to the resistance, the role of gut microbiome remains unclear. In this study, we exposed the M. fortis to the S.japonicum infection, carried out a longitudinal research (uninfected control, infected for 7 days, 14 days, 21 days, and 31 days) on their colonic microbiota based on the 16S rRNA gene amplicon sequencing. The bacterial composition disclosed a disturbance-recovery alteration followed by the resistance to S. japonicum. The alpha diversity of colon microbiota was reduced after the infection, but it gradually recovered along with self-healing process. Further LEfSe analysis revealed that phyla shifted from Firmicutes to Bacteroidetes, which were mainly driven by an increase of Ruminococcaceae and a depletion of Muribaculaceae in the family level along the Control-Infection-Recovery (CIR) process. We identified a temporary blooming of Lactobacillaceae and Lactobacillus in the mid infection stage (D14). As a recognized probiotics repository, we speculate the increased abundance of Lactobacillaceae in M. fortis colonic microbiota might relate to the natural resistance to the schistosome. Besides, potential microbial functions were also significantly changed in the resistance process. These results demonstrate the remarkable alterations of reed vole colonic microbiota in both community structure and potential functions along with the resistance to S. japonicum infection. The identified microbial biomarkers might offer new ways for drug development to conquer human schistosomiasis.

Growth of c-plane and m-plane aluminium-doped zinc oxide thin films: epitaxy on flexible substrates with cubic-structure seeds.

Manufacturing high-quality zinc oxide (ZnO) devices demands control of the orientation of ZnO materials due to the spontaneous and piezoelectric polarity perpendicular to the c-plane. However, flexible electronic and optoelectronic devices are mostly built on polymers or glass substrates which lack suitable epitaxy seeds for the orientation control. Applying cubic-structure seeds, it was possible to fabricate polar c-plane and nonpolar m-plane aluminium-doped zinc oxide (AZO) films epitaxially on flexible Hastelloy substrates through minimizing the lattice mismatch. The growth is predicted of c-plane and m-plane AZO on cubic buffers with lattice parameters of 3.94-4.63 Šand 5.20-5.60 Å, respectively. The ∼80 nm-thick m-plane AZO film has a resistivity of ∼11.43 ±â€…0.01 × 10-4 Ω cm, while the c-plane AZO film shows a resistivity of ∼2.68 ±â€…0.02 × 10-4 Ω cm comparable to commercial indium tin oxide films. An abnormally higher carrier concentration in the c-plane than in the m-plane AZO film results from the electrical polarity along the c-axis. The resistivity of the c-plane AZO film drops to the order of 10-5 Ω cm at 500 K owing to the semiconducting behaviour. Epitaxial AZO films with low resistivities and controllable orientations on flexible substrates offer optimal transparent electrodes and epitaxy seeds for high-performance flexible ZnO devices.

Biochemical synthesis of palladium nanoparticles: The influence of chemical fixatives used in electron microscopy on nanoparticle formation and catalytic performance.

Palladium nanoparticles (PdNPs) can catalyse a range of reductive chemical reactions transforming both organic and inorganic environmental pollutants. PdNPs that ranged from <2 to 2-40 nm were synthesized using chemical methods, and bacterial biomass with/without chemical fixatives. PdNP formation was enhanced by adsorption of Pd(II) to bacterial biomass, followed by fixation with formate or glutaraldehyde. TEM-SAED analyses confirmed that the cell associated PdNPs were polycrystalline with a face-centered cubic structure. Chemically formed PdNPs possessed a higher Pd(0):Pd(II) ratio and produced structurally similar nanoparticles as the biotic systems. These PdNPs were employed to catalyze two, reductive chemical reactions, transforming 4-nitrophenol (4-NP) and hexavalent chromium [Cr(VI)], into 4-aminophenol and Cr(IV), respectively. In the reduction of 4-NP, the catalytic performance was directly proportional to PdNP surface area, i.e., the smallest PdNPs in formate-PdCH34 cells had the fastest rate of reaction. The mass of Pd(0) as PdNPs was the main contributor to Cr(VI) reduction; the chemically synthesized PdNPs showed the highest removal efficiency with 96% at 20 min. The use of glutaraldehyde enhanced the reduction of Pd(II) and promoted PdNPs formation, i.e., creating an artefact of fixation; however, this treatment also enhanced the catalytic performance of these PdNPs.

Selective adsorption of palladium and platinum from secondary wastewater using Escherichia coli BL21 and Providencia vermicola.

It is important to recover precious metals from secondary wastewater because of their low crustal abundance. The selective adsorption of palladium (Pd) and platinum (Pt) ions from secondary wastewater, which contains a large amount aluminium and sodium ions, was investigated using Escherichia coli BL21 (BL21), genetically modified E. coli BL21 (EC20) and Providencia vermicola (P. V.). The results demonstrated that P.V., BL21 and EC20 cells took 95.9%, 88.2% and 97.5% of Pd ions, and 64.8%, 93.2% and 100% of Pt ions form industrial wastewater, respectively. All three bacterial biomass could be reused for Pd adsorption with a second adsorption efficiency of > 85%, specifically, the EC20 cells could absorb 93.8% of Pd ions from wastewater. SEM-EDS and XPS analyses confirmed the occurrence of Pd and Pt on the surface of wastewater-absorbed biomass. The shift in FTIR spectrum implied that functional groups, such as hydroxyl, amino, carboxyl and phosphate groups, were involved in wastewater adsorption.

AllEnricher: a comprehensive gene set function enrichment tool for both model and non-model species.

BACKGROUND: Function genomic studies will generally result in lists of genes that may provide clues for exploring biological questions and discovering unanticipated functions, based on differential gene expression analysis, differential epigenomic analysis or co-expression network analysis. While tools have been developed to identify biological functions that are enriched in the genes sets, there remains a need for comprehensive tools that identify functional enrichment of genes for both model and non-model species from a different function classification perspective. RESULTS: We developed AllEnricher, a tool that calculates gene set function enrichment, with user-defined updatable libraries backing up for both model and non-model species as well as providing comprehensive functional interpretation from multiple dimensions, including GO, KEGG, Reactome, DO and DisGeNET. CONCLUSIONS: AllEnricher incorporates up to date information from different public resources and provides a comprehensive resolution for biologists to make sense out of specific gene sets, making it an advanced open-source tool for gene set function analysis.

Efficient PbSe Colloidal Quantum Dot Solar Cells Using SnO2 as a Buffer Layer.

PbSe colloidal quantum dots (CQDs) are widely used in solar cells because of their tunable band gap, solution processability, and efficient multiple exciton generation effect. The most efficient PbSe CQD solar cells use high-temperature-processed ZnO as the electron transport layer (ETL), limiting their applications in flexible photovoltaics. Currently, low-temperature solution-processed SnO2 has been demonstrated as an efficient ETL for high-efficient PbS CQD and perovskite solar cells because of less parasitic light absorption and higher electron mobility. Herein, we introduce low-temperature solution-processed SnO2 as ETL for PbSe CQD solar cells, and fabricate the PbSe CQD absorber layer with a one-step spin-coating method. The champion device with the structure of FTO (SnO2:F)/SnO2/PbSe-PbI2/PbS-EDT (1,2-ethanedithiol)/Au achieves a high open-circuit voltage of 577.1 mV, a short-circuit current density of 24.87 mA cm-2, a fill factor of 67%, and an impressive power conversion efficiency of 9.67%. Our results pave the way for the development of low-temperature flexible PbSe CQD solar cells.

[Endogenous Release of Nitrogen and Phosphorus in the Danjiangkou Reservoir].

In situ sediments were collected at different sites of the Danjiangkou Reservoir using a columnar sediment sampler, and the release rate of N and P at the sediment-water interface was determined through static incubation experiments and the diffusion model of interstitial water molecules. The results showed that there was a significant difference in the release rate for N and P from sediments collected at five sampling sites. The release rates of NH4+-N and PO43--P under static incubation conditions were 13.07-24.88 mg·(m2·d)-1 and 3.06-6.02 mg·(m2·d)-1, whereas those estimated by Fick's Fist Law were 2.67-7.25 mg·(m2·d)-1 and 0.04-0.18 mg·(m2·d)-1, respectively. Overall, the release rates of N and P in the tributaries were 1.48 and 1.57 times higher than that in the reservoir, respectively, and they tended to decrease from the north to the south. The R/F values of NH4+-N and PO43--P were 3.43-4.98 and 29.67-72.88, respectively. The highest release rates of N and P were observed in the Guojiashan tributary for both methods. However, it was found that the release rates of N and P estimated by Fick's Fist Law were significantly lower than those obtained by the simulation method, indicating that the static incubation experiment with intact sediments allowed the release rates of N and P to be closer to the actual situation compared to the interstitial water molecule diffusion model.

Response of rhizosphere bacterial community of Taxus chinensis var. mairei to temperature changes.

BACKGROUND: Temperature is a key factor influencing the growth and distribution of Taxus chinensis var. mairei, which is of high medicinal value. However, there is little information about the changes in rhizosphere bacterial community of Taxus chinensis var. maire under different temperatures. METHODS: In this study, the rhizosphere bacterial communities of Taxus chinensis var. maire under a series of temperatures [5°C (T5), 15°C (T15), 25°C (T25), 35°C (T35)] were assessed through high-throughput sequencing. And some taxa annotated as Mitochondria were positively correlated with the activity of SOD. RESULTS: Activity of peroxidase (POD) and superoxide dismutase (SOD) were increased and decreased respectively with increasing incubation temperature, showing that SOD may be the dominant reactive oxygen species (ROS) detoxifying enzyme in Taxus chinensis var. maire under low temperature. Taxus chinensis var. maire enriched specific bacterial taxa in rhizosphere under different temperature, and the rhizosphere bacterial diversity decreased with increasing temperature. CONCLUSION: The results indicated that rhizosphere bacteria may play important role for Taxus chinensis var. maire in coping with temperature changes, and the management of rhizosphere bacteria in a potential way to increase the cold resistance of Taxus chinensis var. mairei, thus improving its growth under low temperature and enlarging its habitats.

Hexavalent chromium remediation based on the synergistic effect between chemoautotrophic bacteria and sulfide minerals.

Hexavalent chromium (Cr(VI)) is an environmental concern due to the carcinogenic and mutagenic effect on living organisms. Sulfide minerals based Cr(VI) reduction is an economical and efficient strategy for Cr(VI) remediation. In this study, Cr(VI) reduction through the synergistic effect between chemoautotrophic bacteria and sulfide mineral is systematically investigated. Sulfide minerals dissolution and Cr(VI) reduction performance highly depends on mineral acid soluble property. Cr(VI) reduction capacity of pyrrhotite, pyrite, marcasite and sphalerite was 50, 104, 104 and 44 mg/g (Cr(VI)/mineral) respectively in the biotic system. Acidithiobacillus ferrooxidans (A. ferrooxidans) significantly enhanced pyrite and marcasite based Cr(VI) reduction kinetic and capacity. Proton consumption, iron coprecipitation and the biological activity deficiency in the abiotic system significantly inhibited Cr(VI) reduction. Elemental sulfur and secondary iron mineral as the main composition of the passivation layer inhibited sustainable Cr(VI) reduction. A. ferrooxidans facilitated acid nonsoluble mineral dissolution and surface passivation layer removal, and promoted Cr(VI) reduction. Acid nonsoluble sulfide mineral disulfide bond rapture, S°/Sn2- oxidization, and Fe(III)/Cr(III) dissolution were accelerated by A. ferrooxidans, which facilitated Cr(VI) reduction reactive sites regeneration. Our study demonstrated that chemoautotrophic bacterial accelerated Cr(VI) reduction reaction through promoting acid nonsoluble sulfide mineral dissolution. This research is of environmental and practical significance to remediate redox sensitive contaminant based on the synergistic effect between sulfide minerals and chemoautotrophic A. ferrooxidans.