Composition analysis of acid hydrolysates from Cucurbita moschata Duch.polysaccharides and their effect on oxidative stress resistance of Caenorhabditis elegans

Pumpkin polysaccharides(PPe)have a variety of bioactive effects and our previous research showed the acid hydrolysate(PPe-S,a mixture)from PPe had an antioxidative capacity both in vitro and in viro.The aim of this study was to purify PPe-S and investigate the antioxidant stress effects of 2 purified components(PPe-S-1 and PPe-S-2)using Caenorhabditis elegans as model organism.The results showed that PPe-S-2 had a notable antioxidant effect,and could significantly enhance the activities of antioxidant enzymes including superoxide dismutase(SOD)(P<0.01),catalase(CAT)(P<0.01)and glutathione reductase(GR)(P<0.05),and increase the level of glutathione(GSH)(P<0.01),and decreased the content of malondialdehyde(MDA)(P<0.05).PPe-S-2 could significantly extend the survival time of C.elegans(P<0.01),which were stress-induced by hydrogen peroxide and methyl viologen.PPe-S-2 was a heteropolys accharide composed of glucose,arabinose,rhamnose and galactose with the molar ratio of 1.00:0.03:0.02:0.14.The molecular weight of PPe-S-2 was 0.73 kDa detected by high performance liquid chromatography.These studies demonstrated that PPe-S-2 obtained by the acid hydrolysis of PPe had a prominent protective effect to the damage induced by the intracellular free radical generating agents.

Assessment of COVID-19 aerosol transmission in a university campus food environment using a numerical method

With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.

Numerical Analysis on the Static Performance of Gas Journal Bearing by Using Finite Element Method

In this paper,finite element method is used to calculate the static performance of gas journal bearing,in which rotation speed term is introduced into the stiffness matrix of linear triangular element to realize the performance calculation of the bearing with rotation speed.The results indicate that the average gas film thicknesses corresponding to the maximum load capac-ity and stiffness,and the minimum attitude angle increase with the growth of orifice diameter.Load capacity and stiffness significantly improved with the increase of rotation speed,eccentricity ratio and supply pressure when the bearing has thin average gas film thickness.Attitude angle increases with the growth of rotation speed,while the growth rate slows down or even decreases at high speed.The most effective way of reducing attitude angle is to increase supply pressure.It can be found that rotation speed affects attitude angle through changing gas pressure difference between two orifices,while other parameters have the same effect by changing gas pressure at orifice outlet.

Diversity,evolutionary contribution and ecological roles of aquatic viruses

Aquatic viruses include infected viruses in aquatic animals, plants and microorganisms, and free-floating viruses(virioplankton)in water environments. In the last three decades, a huge number of aquatic viruses, especially diverse free-floating viruses,including cyanophages, phycoviruses, archaea viruses, giant viruses, and even virophages, have been identified by virological experiments and metagenomic analyses. Based on a comprehensive introduction of aquatic virus classification and their morphological and genetic diversity, here, we summarize and outline main virus species, their evolutionary contribution to aquatic communities through horizontal gene transfer, and their ecological roles for cyanobacterial bloom termination and global biogeochemical cycling in freshwater and marine ecosystems. Thereby, some novel insights of aquatic viruses and virus-host interactions, especially their evolutionary contribution and ecological rolesin diverse aquatic communities and ecosystems, are highlighted in this review.

Effects of Chain Entanglement on Liquid-Liquid Phase Separation Behavior of LCST-type Polymer Blends: Cloud Point and Decomposition Rate

By preparing homogenous blend samples with different degrees of chain entanglement, we report an anomalous contribution of chain entanglement to phase separation temperature and rate of poly（methyl methacrylate）/poly（styrene-co- maleic anhydride） （PMMA/SMA） blends presenting a typical lower critical solution temperature （LCST） behavior. The melt- mixed PMMA/SMA blends with a higher chain entanglement density present a lower cloud point （To） and shorter delay time, but lower phase separation rate at the given temperature than solution-cast ones, suggesting that for the polymer blends with different condensed state structure, thermodynamically more facilitation to phase separation （lower Tc） is not necessarily equivalent to faster kinetics （decomposition rate）. The experimental results indicate that the lower Tc of melt-mixed sample is ascribed to smaller concentration fluctuation wavelength （Am） induced by higher entanglement degree, while higher entanglement degree in melt-mixed sample leads to a confined segmental dynamics and consequently a slower kinetics （decomposition rate） dominated by macromolecular diffusion at a comparable quench depth. These results reveal that the chain packing in polymer blends can remarkably influence the liquid-liquid phase separation behavior, which is a significant difference from decomposition of small molecular mixtures.

Design and Simulation of a Highly Sensitive SPR Optical Fiber Sensor

An idea of the surface plasmon resonance(SPR)has been utilized for the design of highly sensitive sensors based on the wagon-wheel fiber technology.Such sensors are sensitive to changes in the refractive index of sample analyte.In this study,a three-strut wagon-wheel structure,coated with the gold layer of nano-sized thickness,has been proposed as the SPR sensor.Finite element method is employed to simulate and tune the proposed SPR's design,which leads to a highly sensitive and multichannel plasmonic sensor with the ability for a dual reading on a single analyte or simultaneous identification of two analytes.In this design,suitable thickness values for the gold layer and core struts are determined.Sensitivities of the detector due to the first resonance peak, second resonance peak,and the difference in resonance peaks are calculated to be 1120nm/RIU, 1540nm/RIU,and 420nm/RIU,respectively,when analytes are placed in all three channels of the fiber.Sensitivity of the detector with respect to the second resonant peak for analyte in Channels 2 and 3 is also found to be 1252nm/RIU when Channel 1 is filled with the reference.The sensitivity and resolution of the sensor increase as the refractive index of the analyte increases by almost a linear proportion.If the sensor is utilized to detect the difference in two peaks,it would substantially reduce the noise,and the best result is expected.The thicknesses of the struts and the gold layer are proper parameters to be tuned in designing the detector.

Diverse and variable sex determination mechanisms in vertebrates

Sex is prevalent in nature and sex determination is one of the most fundamental biological processes, while the way of initiating female and male development exhibits remarkable diversity and variability across vertebrates. The knowledge on why and how sex determination mechanisms evolve unusual plasticity remains limited. Here, we summarize sex determination systems,master sex-determining genes and gene-regulatory networks among vertebrates. Recent research advancements on sex determination system transition are also introduced and discussed in some non-model animals with multiple sex determination mechanisms. This review will provide insights into the origin, transition and evolutionary adaption of different sex determination strategies in vertebrates, as well as clues for future perspectives in this field.

Mesh simplification algorithm based on edge curvature metrics and local optimization

Aiming at the problem that the mesh simplification algorithm loses the geometric features of the model in large-scale simplification,an improved half-edge collapse mesh simplification algorithm is proposed.The concept of approximate measurement of edge curvature is introduced,and the edge curvature is added to the error measure,so that the order of half-edge collapse of the mesh is changed,and the simplified details of the mesh model can be preserved accurately.At the same time,by analyzing the quality of simplified triangular mesh,optimizing triangular mesh locally,reducing the amount of narrow triangles,the quality of the simplified model is improved.The proposed algorithm was tested on Cow model,Car model and Bunny model,and compared with another three algorithms,one of them is a classical mesh simplification algorithm based on edge collapse,the other is an improved algorithm of the classical one.The experimental results show that the improved algorithm can better retain the detail features of the original model at the same reduction ratio,and has reasonable mesh allocation,fast execution speed and small error.