Nanostructures, particularly those from peptide self-assemblies, have attracted great attention lately due to their potential applications in nanotemplating and nanotechnology. Recent experimental ...studies reported that diphenylalanine-based peptides can self-assemble into highly ordered nanostructures such as nanovesicles and nanotubes. However, the molecular mechanism of the self-organization of such well-defined nanoarchitectures remains elusive. In this study, we investigate the assembly pathway of 600 diphenylalanine (FF) peptides at different peptide concentrations by performing extensive coarse-grained molecular dynamics (MD) simulations. Based on forty 0.6–1.8 μs trajectories at 310 K starting from random configurations, we find that FF dipeptides not only spontaneously assemble into spherical vesicles and nanotubes, consistent with previous experiments, but also form new ordered nanoarchitectures, namely, planar bilayers and a rich variety of other shapes of vesicle-like structures including toroid, ellipsoid, discoid, and pot-shaped vesicles. The assembly pathways are concentration-dependent. At low peptide concentrations, the self-assembly involves the fusion of small vesicles and bilayers, whereas at high concentrations, it occurs through the formation of a bilayer first, followed by the bending and closure of the bilayer. Energetic analysis suggests that the formation of different nanostructures is a result of the delicate balance between peptide–peptide and peptide–water interactions. Our all-atom MD simulation shows that FF nanostructures are stabilized by a combination of T-shaped aromatic stacking, interpeptide head-to-tail hydrogen-bonding, and peptide–water hydrogen-bonding interactions. This study provides, for the first time to our knowledge, the self-assembly mechanism and the molecular organization of FF dipeptide nanostructures.
The purpose of the present study was to evaluate the effectiveness of probiotics on type II diabetes mellitus (T2DM).
We performed a comprehensive search on PubMed, Web of Science, China National ...Knowledge Infrastructure, Chinese Scientific Journal Databases, Wan Fang database and China biology medicine disc for relevant studies published before June 2019. Glycated hemoglobin A1c (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR) and fasting blood glucose (FBG) were used as indicators for T2DM. Inverse-variance weighted mean difference (WMD) with 95% confidence interval (CI) was calculated for the mean HbA1c, FBG and HOMA-IR changes from baseline.
15 randomized controlled trials (RCT) with a total of 902 participants were included into the meta-analysis. Considering the clinical heterogeneity caused by variation of dosage and duration of probiotic treatment, random-effects model was used to estimate the pooled WMD. Significantly greater reduction in HbA1c% (WMD = - 0.24, 95% CI - 0.44, - 0.04, p = 0.02), FBG (WMD = - 0.44 mmol/L, 95% CI - 0.74, - 0.15, p = 0.003) and HOMA-IR (WMD = - 1.07, 95% CI - 1.58, - 0.56, p < 0.00001) were observed in probiotics treated group. Further sensitivity analysis verified the reliability and stability of our results.
The results of our meta-analysis indicated that probiotics treatment may reduce HbA1c, FBG and insulin resistance level in T2DM patients. More clinical data and research into the mechanism of probiotics are needed to clarify the role of probiotics in T2DM.
Research studying into student satisfaction has been developing in the light of customer satisfaction theory which considers perceived value and quality as important predictors of student ...satisfaction. But the importance of value co-creation is very much overlooked. Hence this study intends to examine the relationship between perceived value, perceived quality, value co-creation, student satisfaction, complaint and loyalty to give a picture of how perceived value, perceived quality and value co-creation are important predictors of student satisfaction. Partial least square structural equation modelling is adopted to analyse responses from a survey of international students in a Chinese university. Results indicate that perceived value, perceived quality and value co-creation are determinants of student satisfaction which positively influences loyalty and negatively influences complaint. Finally, the research notes that more resources should be dedicated to engaging international students to participate in on-campus management and service work to improve international student studying experience.
•Zhengzhou City had major effect on the pollution of the Jialu River.•TN, OP, TP and CODMn in water drove heavy metals to deposit in sediments.•B-IBI was sensitive to the adverse effect of heavy ...metals in sediments.
This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community.
Epstein-Barr virus (EBV) is closely associated with multiple human cancers. EBV-associated cancers are mainly lymphomas derived from B cells and T cells (Hodgkin lymphoma, Burkitt lymphoma, NK/T-cell ...lymphoma, and posttransplant lymphoproliferative disorder (PTLD)) and carcinomas derived from epithelial cells (nasopharyngeal carcinoma and gastric carcinoma). EBV can induce oncogenesis in its host cell by activating various signaling pathways, such as nuclear factor-κB (NF-κB), phosphoinositide-3-kinase/protein kinase B (PI3K/AKT), Janus kinase/signal transducer and transcription activator (JAK/STAT), mitogen-activated protein kinase (MAPK), transforming growth factor-β (TGF-β), and Wnt/β-catenin, which are regulated by EBV-encoded proteins and noncoding RNA. In this review, we focus on the oncogenic roles of EBV that are mediated through the aforementioned signaling pathways.
Conducting polymers with high theoretical capacitance and deformability are among the optimal candidates for compressible supercapacitor electrode materials. However, achieving both mechanical and ...electrochemical stabilities in a single electrode remains a great challenge. To address this issue, the “Polymer Chainmail” is proposed with reversible deformation capability and enhances stability because of the steric hindrance and charge compensation effect of doped anions. As a proof of concept, four common anions are selected as dopants for Poly(3,4‐ethylenedioxythiophene) (PEDOT), and their effects on the adsorption and diffusion of H+ on PEDOT are verified using density functional theory calculations. Owing to the film formation effect, the
PF6-
${{\rm{PF}}_6^- }$
doped PEDOT/nitrogen‐doped carbon foam exhibits good mechanical properties. Furthermore, the composite demonstrates excellent rate performance and stability due to suitable anion doping. This finding provides new insights into the preparation of electrochemically stable conductive polymer‐based compressible electrode materials.
After the poly(3,4‐ethylenedioxythiophene) (PEDOT) films known as “Polymer Chainmail” were modified by PF−6 anion doping, the ion adsorption and diffusion processes on the PEDOT chains were significantly optimized due to the steric hindrance and charge compensation effects, so the cycling stability (retaining 95.9 % after 20,000 cycles) and rate performance (retaining 81.1 % at 20 mA cm−3) were improved.
Seal damage and cavitation are common faults during centrifugal pump operation. The characterization and recognition of these faults are investigated in this paper to improve the efficiency and ...reliability of pumps. A time-frequency signal analysis method based on the cyclostationary theory is adopted to extract the frequency characteristic components from non-stationary vibration signals under cavitation and seal damage conditions. Specifically, the signal analysis was conducted preliminarily based on the calculation of cyclic autocorrelation functions (CAFs) for various signals. Corresponding slices are extracted from the CAFs and processed by fast Fourier transform (FFT) method. Consequently from the FFT spectra, indicators for characterization are extracted to demonstrate the occurrence and severity of faults. Results show that the indicators for seal damage characterization are 100 and 600-Hz frequency components in slice α = 600 Hz of CAF corresponding to shaft and blade passing frequency in the frequency domain of vibration signals. Meanwhile, the occurrence and development status of cavitation are indicated by the frequency component of 200 Hz in slice α = 600 Hz of CAF. Additionally, the effect of instability caused by off-design, seal damage, and cavitation operation conditions are distinguished by cyclic spectra analysis. Characteristic components are innovatively extracted at specific frequencies to avoid the effect from modulated and noise components in vibration signals. And the results about recognition of different types of faults could provide important evidences for fault detection during pump operation.
Centrifugal pumps are essential in many industrial processes. An accurate operation diagnosis of centrifugal pumps is crucial to ensure their reliable operation and extend their useful life. In real ...industry applications, many centrifugal pumps lack flowmeters and accurate pressure sensors, and therefore, it is not possible to determine whether the pump is operating near its best efficiency point (BEP). This paper investigates the detection of off-design operation and cavitation for centrifugal pumps with accelerometers and current sensors. To this end, a centrifugal pump was tested under off-design conditions and various levels of cavitation. A three-axis accelerometer and three Hall-effect current sensors were used to collect vibration and stator current signals simultaneously under each state. Both kinds of signals were evaluated for their effectiveness in operation diagnosis. Signal processing methods, including wavelet threshold function, variational mode decomposition (VMD), Park vector modulus transformation, and a marginal spectrum were introduced for feature extraction. Seven families of machine learning-based classification algorithms were evaluated for their performance when used for off-design and cavitation identification. The obtained results, using both types of signals, prove the effectiveness of both approaches and the advantages of combining them in achieving the most reliable operation diagnosis results for centrifugal pumps.
•Susceptible mice showed depressive-like behaviors upon chronic social defeat stress.•Plasma corticosterone concentration might predict susceptibility to chronic stress.•Abnormal glucocorticoid ...receptor expression was associated with susceptibility.•Ketamine exerted antidepressant effect via normalizing HPA axis response.
Chronic stress is an important factor for depression. Most individuals recover from stress, while some develop into depression. The pathogenesis of resilience or susceptibility remains unclear. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis and releases stress hormones to regulate individual response to stress. Hence, we assessed the effects of chronic social defeat stress (CSDS) on susceptible behaviors, plasma corticosterone (CORT) concentration, glucocorticoid receptor (GR) expressions in hippocampus and medial prefrontal cortex (mPFC). Mice that plasma CORT concentration is increased 2 h after single social defeat stress developed into susceptible mice after 10 d social defeat stress. The plasma CORT concentration was still higher than that of resilient mice 48 h after the last defeat stress. Mice administered CORT via drinking water showed susceptibility. Mifepristone, a GR antagonist improved susceptibility to chronic stress. Single dose ketamine treatment improved depressive-like behaviors, decreased plasma CORT concentration, rescued GR expression and nuclear translocation in the hippocampus of susceptible mice. These results suggested that abnormal CORT concentration after stress may predict susceptibility to depression in clinic. Ketamine may exert the antidepressant effect via normalizing HPA axis response and have significance in the clinic.
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