A density functional theory study of a water gas shift reaction on Ag(111): potassium effect.

Density functional theory (DFT) calculations are executed to investigate the effect of a potassium (K) promoter on the activity of the water gas shift reaction (WGSR) over an Ag(111) surface. It is found that the WGSR proceeds mainly through the OH(O)-assisted carboxy pathway in which H2O dehydrogenation is the rate-controlling step on both Ag(111) and K/Ag(111) surfaces. Energetic span model analysis shows that K addition can enhance the activity of the WGSR by reducing the apparent activation energy of the whole reaction since it can promote H2O dissociation and stabilize the adsorption of the reactants (CO and H2O). Importantly, the K adatom can stabilize the binding of all oxygenates by direct K-O bonding and the stabilizing effect of K on OH adsorption of the transition state (TS) plays a leading role in promoting H2O dissociation. Moreover, the K-O distance and K coverage are two key factors affecting H2O activation, that is, the shorter the K-O distance (2-3 Å) the more the K coverage (25%) contributes to the stronger promotion effect. For various metals catalyzing the WGSR, K promotes H2O dissociation on inert metals like Ag, Au and Cu better than those on reactive metals (Pd and Ni) since the more inert metal surfaces would weaken the K and O binding and accordingly strengthen the interaction between them, resulting in a higher promotion effect.

Effectiveness of traditional Chinese medicine in treating gastrointestinal dysfunction in patients with acute stroke: a systematic review and meta-analysis of 16 randomized controlled trials.

BACKGROUND: Gastrointestinal dysfunction is one of the complications after stroke. If it is not treated in time, it will affect the rehabilitation process after stroke and reduce the quality of life of patients. In this study, we conducted a systematic review and meta-analysis of the reports on the treatment of gastrointestinal dysfunction after stroke with traditional Chinese medicine (TCM) in recent years to provide evidence for clinical diagnosis and treatment. METHODS: The clinical randomized controlled trials (RCTs) published in Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), Medline, and Web of Science databases from January 2010 to August 2021 were searched. After screening the qualified literatures, literature quality evaluation was performed. The software Stata 16.0 was used to analyze and compare the outcome indicators of TCM and conventional western medicine treatment, and the utility of TCM in the treatment of gastrointestinal disorders after stroke was comprehensively evaluated. RESULTS: A total of 16 studies were finally selected including a total of 1,589. Meta-analysis showed that TCM treatment of gastrointestinal disorders after stroke was more effective than conventional western medicine treatment [odds ratio (OR) =3.94; 95% confidence interval (CI): 2.63 to 5.89; P=0.000]. It was also shown that TCM can reduce the recovery time of bowel sounds and is superior to conventional western medicine [standard mean difference (SMD) =-1.92; 95% CI: -2.51 to -1.34; P=0.000]; reduce defecation and flatulence recovery time (SMD =-2.51; 95% CI: -3.41 to -1.61; P=0.000); increase gastrin level (SMD =0.80; 95% CI: 0.35 to 1.25; P=0.001); increase motilin level (SMD =2.27; 95% CI: 1.55 to 3.00; P=0.000); increase serum albumin level (SMD =0.72; 95% CI: 0.54 to 0.90; P=0.000); increase transferrin levels (SMD =1.11; 95% CI: 0.86 to 1.36; P=0.000); and it can increase serum prealbumin levels (SMD =1.50; 95% CI: 0.78 to 2.22; P=0.000). DISCUSSION: The use of TCM in the treatment of gastrointestinal dysfunction after stroke can effectively reduce symptoms, shorten the recovery time of bowel sounds, the first defecation and flatulence time, promote gastric motility and gastrointestinal hormone secretion, and improve the nutritional status of patients.

Graphene Oxide Nanofiltration Membranes Containing Silver Nanoparticles: Tuning Separation Efficiency via Nanoparticle Size.

Three types of graphene oxide/silver nanoparticles (GO/AgNPs) composite membranes were prepared to investigate size-effect of AgNPs on nanofiltration ability. The size of AgNPs was 8, 20, and 33 nm, which was characterized by UV-visible spectroscopy and transmission electron microscopy. The morphology and structure of GO and GO/AgNPs composite membranes were characterized by atomic force microscopy, scanning electron microscopy, and X-ray diffraction. The filtration performance of membranes were evaluated on a dead-end filtration device. When the size of AgNPs is 20 nm, the GO/AgNPs composite membrane has the highest water flux (106.1 L m-2 h-1 bar-1) and rejection of Rhodamine B (RhB) (97.73%) among three types of composite membranes. The effect of feed concentration of dye solution and the flux of common solvent was also investigated. The mechanism was discussed, which demonstrated that both interlaying spacing and defect size influence the filtration ability of membrane, which is instructive to future study.

The Preparation and Study of Ethylene Glycol-Modified Graphene Oxide Membranes for Water Purification.

In this work, graphene oxide (GO)/ethylene glycol (EG) membranes were designed by a vacuum filtration method for molecular separation and water purification. The composite membranes were characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The interlayer spacing of GO membranes (0.825 nm) and GO/EG membranes (0.634 nm) are measured by X-ray diffraction (XRD). Using the vacuum filtration method, the membrane thickness can be controlled by selecting the volume of the solution from which the membrane is prepared, to achieve high water permeance and high rejection of Rhodamine B (RhB). The membrane performance was evaluated on a dead-end filtration device. The water permeance and rejection of RhB of the membranes are 103.35 L m-2 h-1 bar-1 and 94.56% (GO), 58.17 L m-2 h-1 bar-1 and 97.13% (GO/EG), respectively. The permeability of GO/EG membrane is about 40 × 10-6 L m-1 h-1 bar-1. Compared with the GO membrane, the GO/EG membrane has better separation performance because of its proper interlayer spacing. In this study, the highest rejection of RhB (99.92%) is achieved. The GO/EG membranes have potential applications in the fields of molecular separation and water purification.

Water dissociation on K2O-pre-adsorbed transition metals: a systematic theoretical study.

It is imperative to regulate O-H bond cleavage on metal surfaces with a pre-adsorbed K2O promoter in heterogeneous catalysis. Density functional theory (DFT) calculations have been performed to explore the adsorption and dissociation of water on K2O-pre-adsorbed transition metal surfaces (Au, Ag, Cu, Ni, Pt, Rh, Ir, Pd, Ru, Co and Fe) as compared with those on clean and K-pre-adsorbed metal surfaces. The calculation results indicate that the presence of K2O species significantly promotes water dissociation and the promoting effect depends on the adsorption strength of K2O, namely, the more strongly K2O binds to the metal surface, the less promoting effect it has on the water O-H bond cleavage. Based on geometrical and electronic analysis, the stronger promoting effect of K2O than K on water dissociation on the given metal surfaces can be attributed to stronger attractive electrostatic interactions between OH and the dissociating H of H2O at the TSs as well as between O of H2O and K of K2O at the ISs on K2O-pre-adsorbed surfaces compared with those on K-pre-covered surfaces. Moreover, the additional hydrogen bond interaction between H and Oad of K2O at the ISs on Cu/Ag/Au and Fe/Co/Ni metals would be responsible for the much greater promoting effect of K2O than K on these metal surfaces, while there is a slightly greater promoting effect of K2O on the remaining metal surfaces. From the above analysis, we expect our studies can provide profound understanding of the nature of the promoting effect of K2O on O-H bond scission.

Heterologous Expression and Characterization of a Novel Chitinase (ChiEn1) from Coprinopsis cinerea and its Synergism in the Degradation of Chitin.

Chitinase ChiEn1 did not hydrolyze insoluble chitin but showed hydrolysis and transglycosylation activities toward chitin-oligosaccharides. Interestingly, the addition of ChiEn1 increased the amount of reducing sugars released from chitin powder by endochitinase ChiIII by 105.0%, and among the released reducing sugars the amount of (GlcNAc)2 was increased by 149.5%, whereas the amount of GlcNAc was decreased by 10.3%. The percentage of GlcNAc in the products of chitin powder with the combined ChiIII and ChiEn1 was close to that in the products of chitin-oligosaccharides with ChiEn1, rather than that with ChiIII. These results indicate that chitin polymers are first degraded into chitin oligosaccharides by ChiIII and the latter are further degraded to monomers and dimers by ChiEn1, and the synergistic action of ChiEn1 and ChiIII is involved in the efficient degradation of chitin in cell walls during pileus autolysis. The structure modeling explores the molecular base of ChiEn1 action.

[Effect of Electroacupuncture on Expression of 5-HT7 Receptor in Periaqueductal Gray and Plasma Calcitonin Gene-related Peptide in Migraine Rats].

OBJECTIVE: To explore the analgesic effect of electroacupuncture(EA)by modulating 5-hydroxytryptamine 7 (5-HT7) receptor in periaqueductal gray (PAG) and plasma calcitonin gene-related peptide (CGRP). METHODS: Forty-two male Sprague Dawley (SD) rats were randomly divided into control，model and EA groups, 14 rat in each one. The neurogenic migraine model was established by repeated electrical stimulation on sagittal sinus duramater. Intracranial electrodes were used in the control group without stimuli. The rats in the EA group received EA (0.5－1 mA, 2 Hz/15 Hz) at "Fengchi" (GB 20) for 10 min after dural electrical stimulation, once a day for 6 days. The expression of 5-HT7 receptor in the PAG was assessed by immunofluorescence and Western blot, respectively; plasma CGRP was measured by radioimmunoassay. RESULTS: Compared with the control group, the positive neuron number and protein expression of 5-HT7 receptor in PAG and plasma CGRP increased after model establishment (all P<0.001). The above mentioned indexes were reversed in the EA group compared with those in the model group (the positive neuron number and protein expression of 5-HT7 receptor, P<0.01; plasma CGRP, P<0.05). CONCLUSIONS: EA at GB 20 can down-regulate the expression of 5-HT7 receptor in the PAG and reduce the content of plasma CGRP in the rats of migraine.

The influence of structural isomerism on fluorescence and organic dye selective adsorption in two complexes based on flexible ligands.

Based on Cd(NO3)2·4H2O and 4,4'-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), two isomeric coordination polymers, {[Cd1.5(cpbda)(bpa)(H2O)2]·1.5H2O}n (1), [Cd(H2cpbda)2(bpa)0.5(H2O)]n (2), were synthesized by using different solvent-systems. The complexes were characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. Owing to the obvious structural difference between the two isomeric complexes, the further fluorescence sensing and dye selection and adsorption were investigated. The 3D tight stacking structure of 1 strengthened the fluorescence emission and the loose 2D layer structure of 2 generated the active selection and adsorption of the Malachite Green Oxalate (MGO) dye.

Diabetes impairs spatial learning and memory and hippocampal neurogenesis via BDNF in rats with transient global ischemia.

Diabetic conditions worsen the prognosis of stroke. The molecular mechanism underlying the impairment of post-stroke recovery is not very clear. Here, we establish a rat model resembling human cerebral infarction with or without diabetes to determine how diabetes impairs cognitive recovery. Our data show that diabetes inhibits hippocampal BDNF expression and impairs the survival and differentiation of the newborn neural cells in rats with ischemia. Consequently, the rats of diabetic ischemia have a significantly lower score in spatial learning and memory in the Morris water maze test than the non-diabetic ischemia model rats. On the other hand, treatment with BDNF effectively improves hippocampal neurogenesis and the spatial learning and memory in rat with diabetic ischemia. All together, our data suggest that diabetes impaired spatial learning and memory and hippocampal neurogenesis in rats with ischemia by inhibition of the BDNF expression in the hippocampus.

MnO2 Nano-Urchin/Graphene Hybrid Electrodes: Facile Synthesis and Enhanced Supercapacitance Performance.

MnO2 with urchin-like nano/micro hierarchical architecture was synthesized through an easy hydrothermal method at low temperature and used to prepare MnO2/graphene hybrid composite as electrode materials through an easy and efficient solution-based method. The MnO2 particles in the composite with 66.7% mass ratio could achieve specific capacitance as high as 451.5 F g(-1) at a scan rate of 10 mV s(-1) and exhibit good cycle stability with 93.8% capacitance retention over 2000 cycles. These properties result from the unique urchin-like nano/micro hierarchical structure of MnO2 as well as the function of graphene in enhancing the conductivity and utilization of MnO2.

Linking groundwater dissolved organic matter to sedimentary organic matter from a fluvio-lacustrine aquifer at Jianghan Plain, China by EEM-PARAFAC and hydrochemical analyses.

The sources of dissolved organic matter (DOM) in groundwater are important to groundwater chemistry and quality. This study examined similarities in the nature of DOM and investigated the link between groundwater DOM (GDOM) and sedimentary organic matter (SOM) from a lacustrine-alluvial aquifer at Jianghan Plain. Sediment, groundwater and surface water samples were employed for SOM extraction, optical and/or chemical characterization, and subsequent fluorescence excitation-emission matrix (EEM) and parallel factor analyses (PARAFAC). Spectroscopic properties of bulk DOM pools showed that indices indicative of GDOM (e.g., biological source properties, humification level, aromaticity and molecule mobility) varied within the ranges of those of two extracted end-members of SOM: humic-like materials and microbe-associated materials. The coexistence of PARAFAC compositions and the sustaining internal relationship between GDOM and extracted SOM indicate a similar source. The results from principal component analyses with selected spectroscopic indices showed that GDOM exhibited a transition trend regarding its nature: from refractory high-humification DOM to intermediate humification DOM and then to microbe-associated DOM, with decreasing molecular weight. Correlations of spectroscopic indices with physicochemical parameters of the groundwater suggested that GDOM was released from SOM and was modified by microbial diagenetic processes. The current study demonstrated the associations of GDOM with SOM from a spectroscopic viewpoint and provided new evidence supporting SOM as the source of GDOM.

[Pollution characteristics and distribution of polycyclic aromatic hydrocarbons and organochlorine pesticides in groundwater at Xiaodian Sewage Irrigation Area, Taiyuan City].

Sewage irrigation has been widely used in areas of water shortage in northern China, and it may introduce organic contaminants into groundwater. To characterize the organic contaminants in groundwater in sewage irrigation area, the Xiaodian sewage irrigation area in Shanxi Province was chosen as the case study area. A total of 16 groundwater samples (13 from shallow aquifer, 3 from deep aquifer) were collected. Polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography-mass spectrometry (GC-MS) and organochlorine pesticides (OCPs) were ainalyzed by gas chromatography-electron capture detection (GC-ECD). The results showed that the concentrations of PAHs ranged from 13.98 to 505.89 ng x L(-1) with an average concentration of 115.67 ng x (L)(-1). The 2 and 3 ring-PAHs were the main components, while naphthalene and phenanthrene were most frequently detected. The concentrations of OCPs were in the range of 13.91-103.23 ng x L(-1) with an average concentration of 40.99 ng x L(-1), while alpha-HCH, delta-HCH, o,p'-DDD, Aldrin, Endosulfan-sulfate and HCB were most frequently detected. Overall, shallow aquifers appeared more contaminated with these pollutants than deep aquifers. In the area, the order of the organic contaminants concentration in groundwater was: East Main Channel < Beizhang Drainage < Taiyu Drainage, which indicated the quality of groundwater was influenced by the sewage irrigation.

[Structure and biological functions of mammalian LEM-domain proteins].

During the process of open mitosis in higher eukaryotic cells, the nuclear envelope (NE) is disassembled and reassembled with highly organized and periodical dynamic morphological changes. Recent studies demonstrated that LEM-domain protein family mediates interactions among inner nuclear membrane, nuclear lamina protein and chromatin by interacting with barrier-to-autointegration-factor (BAF). The structure and function of the ternary complex formed by LEM-domain protein, nuclear lamina protein and BAF are dependent on each other. Moreover, the network formation based on this structure and function is critical for the development of basic biological processes of nuclear, and it plays important roles in chromatin separation in late metaphase and anaphase, NE reassembly after mitosis, morphological maintenance of nuclear and NE in interphase, regulation of DNA replication and DNA damage repair, regulation of gene expression and signaling pathway, and infection of retrovirus. Mutations in genes encoding LEM family proteins have important impacts on development and progression of laminopathic diseases and tumorigenesis. This review provides a detailed summary of structural and functional studies of the LEM family proteins.

Experimental degradation of nonylphenol (endocrine disruptor) by using ultraviolet irradiation in the presence of hydrogen peroxide.

The photodegradation of nonylphenol under UV irradiation was investigated in an aqueous solution containing hydrogen peroxide (H2O2) as the photochemically active substance was investigated. Influences of pH, the concentration of hydrogen peroxide, and the initial concentration of nonylphenol were studied. The following conditions were determined as optimal for nonylphenol removal: pH 1, H2O2 concentration of 40 mg/L, and an initial nonylphenol concentration of 15 of mg/L. Under these conditions, the removal of nonylphenol reached about 80% after 2 hours of irradiation. Identification of degradation products was done by gas chromatography-mass spectrometry, and analyses revealed Benzaldehyde, 4-methoxy and Diisobutyl phthalate as the main products of nonylphenol photodegradation.

Isolation and characterization of a radiation-resistant bacterium from Taklamakan Desert showing potent ability to accumulate Lead (II) and considerable potential for bioremediation of radioactive wastes.

Radioactive wastes always contain radioactive substances and a lot of Pb compound and other heavy metals, which severely contaminate soils and groundwater. Thus, search for radiation-resistant microorganisms that are capable of sequestering Pb contaminants from the contaminated sites is urgently needed. However, very few such microorganisms have been found so far. In the present study, we discovered a novel Gram-negative bacterium from the arid Taklamakan desert, which can strongly resist both radiation and Pb(2+). Phylogenetic and phenotypic analysis indicated that this bacterial strain is closely affiliated with Microvirga aerilata, and was thus referred to as Microvirga aerilata LM (=CCTCC AB 208311). We found that M. aerilata LM can effectively accumulate Pb and form intracellular precipitations. It also keeps similar ability to remove Pb(2+) under radioactive stress. Our data suggest that M. aerilata LM may offer an effective and eco-friendly in situ approach to remove soluble Pb contaminants from radioactive wastes.

The source apportionment of polycyclic aromatic hydrocarbons (PAHs) in the topsoil in Xiaodian sewage irrigation area, North of China.

31 topsoil samples were collected by grid method in Xiaodian sewage irrigation area, Taiyuan City, North of China. The concentrations of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatograph coupled with mass spectrum. Generally speaking, the distribution order of PAHs in the area is: those with five and six rings > those with four rings > those with two and three rings. Source apportionment shows a significant zonation of the source of PAHs: the civil coal pollution occurred in the north part, the local and far factory pollution happened in the middle area and the mixed pollution sources from coal and wood combustion, automotive emission, presented in the south area. The distribution of PAHs has a definite relationship with the sewage water flow and soil adsorption. The related coefficient between PAHs and physicochemical property showed there was a negative correlation between pH, silt, clay and PAHs while there was a positive correlation between total organic carbon, sand and PAHs.

[Vertical distribution and possible sources of polycyclic aromatic hydrocarbon in sewage area soil].

Nine profile soil samples were collected from Xiaodian sewage irrigation area, Taiyuan city, China. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography equipped with a mass spectrometry detector (GC/ MS). The rank order of the average concentrations of PAHs in the 0-10 cm upper soil layer was background area < swamp area < groundwater irrigation area < sewage irrigation area. The concentrations of PAHs in most profile soils decreased with the increase of depth, and the PAHs were mainly accumulated in the surface soil layer (0-40 cm). 4-6 rings of PAHs were mainly accumulated in the 0-50 cm soil layer, and the accumulation capacity in groundwater-irrigation area was better than that in sewage irrigation area. The correlation between different rings of PAHs and TOC was positive (r(max) = 0.791, P = 0), and the same situation was found for PAHs and sand (r(max) = 0. 882, P = 0). The correlation between PAHs and pH was negative (r(min) = -0.1, P = 0.702). The main source of PAHs in the surface soil layer (0-40 cm) of study area was coal combustion. There were two pollution ways of PAHs in soil, one was settled into soil directly, the other was first settled into water and absorbed on the surface of solid particles, and then got enrichment in soil as irrigation water flew.

[A study of cerebral cortex in untreated first-episode schizophrenics].

OBJECTIVE: To detect the changes of cortical thickness and cortical surface area in untreated patients of first-episode schizophrenia. METHODS: Fifty-seven untreated patients of first-episode schizophrenia (SCZ) hospitalized from September 2009 to March 2012 at Department of Psychiatry, Third Affiliated Hospital, SUN Yat-sen University and 57 healthy controls (HC) recruited by advertising during the same period underwent a high resolution three-dimensional magnetic resonance imaging of brain structures. And cortical-surface based technique was used to analyze the cortical thickness and cortical surface area. The general linear model (GLM) was employed to detect the differences of cortical thickness and cortical surface area between two groups. RESULTS: were corrected for multiple comparisons by the Monte Carlo simulation method. RESULTS: As compared with HC, the cortical thickness of left superior frontal, left caudal middle cingulate, left lateral occipital, right superior frontal, right superior temporal and right fusiform regions in SCZ decreased by 6.0%, 7.2%, 8.2%, 5.2%, 7.1% and 6.0% respectively. And the largest reductions occurred in left lateral occipital regions. Cortical surface area of each brain regions in SCZ had no significant difference with HC. CONCLUSION: Cortical thickness reductions exist in multiple brain regions in schizophrenia. It may be the neuropathological mechanisms of schizophrenia.

[Variation characteristics of relative molecular mass of different fractions of dissolved organic matter from landfill leachate during photocatalytic degradation].

Gel permeation chromatography was applied to analyze the variation characteristics of molecular mass of DOM six fractions during photocatalytic degradation. The results showed that most of DOM with average relative molecular mass was below 10(4). Large molecular fractions higher than 10(4) mainly containing HIB and HIN, accounted for nearly 20% of total DOM. Relative molecular mass of other fractions was mainly from 10(3) to 10(4). Fractions with relative molecular mass less than 500 were little. Most of DOM in leachate was yellow humic acid with moderate relative molecular mass and that is difficult to be biologically degraded. Relative molecular mass distribution of DOM fraction in different effluent broadened gradually during photocatalytic process, while polydispersity distribution coefficient (D) increased gradually. Relative molecular mass of HOB, HIB, HIA and HON decreased notably after photocatalytic treatment, especially HOB which relative molecular mass decreased from initial (4-25) x 10(3) to (0.4-1) x 10(3) after 72 h degradation. On the contrary, relative molecular mass of HOA and HIN tended to increase, and the more obvious is HOA which relative molecular mass increased from (2-20) x 10(3) of raw leachate to (20-50) x 10(3) of 72 h effluent. RID peak signal intensity of each DOM fraction decreased with the treatment time, which illustrated that the concentration decreased. As a whole, all fractions of DOM can be photocatalytically transformed efficiently.

[Diffusion tensor imaging analyses of white matter at an early stage of first-episode schizophrenia].

OBJECTIVE: To explore the roles of diffusion tensor imaging (DTI) of white matter at an early stage of schizophrenia. METHODS: The participants were 20 first-episode, medication-naïve schizophrenics at an early stage (1 - 6 months) and 20 healthy controls adjusted in gender and age during December 2009 and October 2010. They underwent diffusion weighted magnetic resonance imaging with a single-shot echo planar imaging (EPI) sequence aligned to straight axial plane. The fractional anisotropy (FA) images of two groups underwent two-sample paired t-test with SPM5 software. RESULTS: The schizophrenics at an early stage demonstrated a significant decrease of regional white matter FA values in right anterior cingulated (MNI: x = 12, y = 24, z = -10; cluster = 145) and right middle occipital lobe (MNI: x = 36, y = -76, z = -2; cluster = 135). CONCLUSION: The altered white matter DTI in right anterior cingulated and middle occipital lobe may contribute to an early detection of schizophrenia.