Search

Bio-based hydrogels formed by the chemically or physically cross-links are promising materials in the biological system. In this paper, we propose a constitutive model within the framework of finite-strain viscoelasticity to investigate the mechanical behaviors of bio-based polyelectrolyte complex (PEC) hydrogels from the ionic complexation of sodium hyaluronate (HA)/chitosan with and without chemical crosslinkers. The structure of the viscoelastic constitutive model consists of a spring and a Kelvin element, in which two softening factors are adopted to represent the states of ionic bonds and bridges in the hydrogels. Based on some constitutive assumptions and through the conventional approach of thermodynamics, the constitutive equation system of the model is derived. Corresponding to the hydrogels with different crosslinker concentrations, the values of material parameters in the model are identified. To show the validity of the model, it is applied to simulate the mechanical behaviors of the hydrogel samples in the uniaxial tensile tests and cyclic loading–unloading tests. It is found that the model predictions can fit the experimental data quite well. Based on the modeling results, some further analyses regarding the effects of softening factors on the response of HA/chitosan hydrogels have also been conducted. • A viscoelastic model is proposed to study the mechanical behaviors of PEC hydrogels. • Two softening factors are adopted to represent the states of ionic bonds and bridges. • Parameters are identified for hydrogels with different crosslinker concentrations. • The mechanical response of PEC hydrogels can be predicted accurately by the model. • The effects of softening factors on the response of PEC hydrogels are analyzed. [ABSTRACT FROM AUTHOR]

This study examines whether people smoked more under the Coronavirus Disease 2019 (COVID-19) closure policies which trapped them at home with their families. In such circumstances, the pleasure from smoking could be more tempting than usual, but at the same time smokers' families are more likely to be victims of passive smoking. This study uses temporal and regional variations in policy strengths with data from the Oxford COVID-19 Government Response Tracker project (OxCGRT) to examine the impact of COVID-19 closure policies on smoking behaviors. With longitudinal data from the China Family Panel Studies (CFPS) in 2018 and 2020, we find diminished smoking behaviors among Chinese male adults when the government implemented strict public health policies for the COVID-19 pandemic. People with more conscientiousness personality traits or stronger pro-family attitudes tend to smoke less as policy stringency increases. • This paper examines whether people smoke more under COVID-19 closure policies. • Policy stringency is the average OxCGRT score in the past 30 days before survey. • We find people smoke less when the index of policy stringency becomes higher. • Conscientious personality traits and pro-family attitudes are proxies of altruism. • The discouraging effects are stronger among people with higher family altruism. [ABSTRACT FROM AUTHOR]

A novel Janus sponge with the ability to remove complex contaminants from water is reported. Firstly, a superhydrophilic sponge (PA@PEI-sponge) is prepared via synthesizing negatively charged phytic acid@polyethyleneimine (PA@PEI) nanoparticles and assembling them on the surface of polydopamine (PDA) and PEI-modified polyurethane (PU) sponge through electrostatic adsorption. The Janus sponge is generated by modifying one side of the PA@PEI-sponge with PDMS, which exhibits superior separation efficiency and high filtration flux toward both water-in-oil and oil-in-water emulsions due to its multiplex selective wettability and the interconnected and tortuous 3D porous channels. The numerous negatively charged active sites of PA@PEI nanoparticles and PDA layer impart the superhydrophilic PA@PEI-sponge with the removal efficiency of 39.95 ± 0.27% for malachite green (MG) via simple flow-through filtration, which can be improved to 99.92 ± 0.07% by Janus modification. More importantly, the Janus sponge exhibits an excellent treatment capacity for complex mixtures containing emulsified oil and dye, with the separation efficiency above 99.59%. The Janus sponge also demonstrates the effective separation of real industrial wastewater collected from an acrylic dyeing plant. Together with a facile and green preparation strategy, this Janus sponge shows excellent application potential for simultaneous dye removal and oil/water emulsion separation. [Display omitted] • An eco-friendly Janus sponge is prepared using a facile and green strategy. • The Janus sponge can separate both water-in-oil and oil-in-water emulsions. • The Janus modification promotes the dye removal efficiency from 39.95% to 99.92%. • The Janus sponge exhibits an excellent treatment capacity for complex wastewater. [ABSTRACT FROM AUTHOR]

The emergence of the novel GII.17 Kawasaki 2014 norovirus variant raising the interest of the public, has replaced GII.4 as the predominant cause of noroviruses outbreaks in East Asia during 2014–2015. Antigenic variation of the capsid protein is considered as one of the key mechanisms of norovirus evolution. In this study, we screened a panel of GII.17 mutants. First, we produced norovirus P proteins using cell-free protein synthesis (CFPS) system, comparing the results to pure proteins expressed in a cell-based system. Next, we determined the binding capability of specific monoclonal antibody (mAb) 2D11 using a unique set of wild-type GII.17 strains. Results of the EIA involving a panel of mutant cell-free proteins indicated that Q298 was the key residue within loop 1. These data highlighted the essential residues in the linear antibody binding characteristics of novel GII.17. Furthermore, it supported the CFPS as a promising tool for rapidly screening mutants via the scalable expression of norovirus P proteins. [ABSTRACT FROM AUTHOR]

• Axial back-and-forth-reflection (BFR) inside capillary was investigated. • A photometer based on axial -BFR inside capillary was proposed. • Optical-path enhancement of axial -BFR is more efficient than that of radial -BFR. • In comparison with radial -BFR, axial -BFR features low transmission loss. • The photometer features high sensitivity, compact, low cost and easy fabrication. As for photometry analysis, increasing the optical-path (OP) via multi-reflection is an effective method for improving the detection sensitivity. In this paper, a photometer based on axial multi-reflection between two end-faces of capillary was proposed and investigated. The probe light can be back and forth reflected inside the capillary, by employing apertured silver-mirrors at both ends of a metal-capillary. With designed aperture profile (i.e., a central disc-aperture and a peripheral ring-aperture) of the mirror, a 4.2-fold enhancement on OP was realized (i.e., OP is 4.2 times the capillary length). Moreover, the photometer was applied to detecting nitrite with a detection limit of 1 nM, which exhibits 8.6~15 fold improvement compared with that of previous photometers with similar capillary length and the same chromogenic reagent without sample enrichment. The photometer features compact, low cost and easy fabrication. [ABSTRACT FROM AUTHOR]

A reliable and high-performance oxygen (O 2) sensor based on TiO 2 -decorated bridging Gallium Nitride nanowires (TiO 2 /GaN NWs) was fabricated, which operates under ultraviolet (UV) irradiation at room temperature (RT). The TiO 2 /GaN NWs were prepared by direct-bridge growth of GaN NWs across the trench of GaN coated sapphire substrate, followed by titanium (Ti) sputtering and thermal oxidation. The morphology characteristic shows that TiO 2 nanoparticles (NPs) are anchored uniformly on the surface of GaN NWs. The sensors with various TiO 2 film thickness (0, 2, 5, 10 nm) were measured at RT under 365 nm UV illumination with O 2 concentrations varying from 1% to 25%. Experimental results show that when the TiO 2 film thickness is 5 nm, the O 2 response reaches its maximum and the limit of detection (LOD) as low as 0.45% O 2. Moreover, the 5 nm TiO 2 /GaN NWs sensor were also measured under different wavelengths (λ = 280, 365, 450 nm) UV illumination and found that the lower light wavelength, the higher O 2 sensing. In addition, the sensor has excellent repeatability, selectivity and long-term stability, thus has a wide application in the field of O 2 gas sensing. [Display omitted] • A oxygen gas sensor based on TiO 2 /GaN NWs was fabricated and well studied. • The sensor operates in air atmosphere under UV illumination (λ = 365 nm) at room temperature (∼25 ℃). • When the TiO 2 thickness is 5 nm, the O 2 response reaches its maximum and the limit of detection ∼ 0.45% O 2. • The sensor has excellent repeatability, selectivity and long-term stability. • Oxygen response under different UV wavelengths was also studied. [ABSTRACT FROM AUTHOR]

Human noroviruses (HuNoVs) have been found as the leading cause of acute gastroenteritis outbreaks in all age groups and are significantly correlated with the consumption of shellfish. In this study, the contamination of HuNoVs in shellfish was estimated through a systematic review and meta-analysis. Studies on the contamination of HuNoVs in shellfish were searched from PubMed, Web of Science, Embase, and Cochrane Library from January 2000 to August 2021. A total of 75 studies were included, and the pooled HuNoVs prevalence in shellfish was 29% (95% CI: 23–35) worldwide. As revealed by the results of the subgroup meta-analysis, the prevalence of dominant genogroup was variable, and 4% (95% CI: 3–6), 13% (95% CI: 10–17), with 7% (95% CI: 4–11) of the samples, respectively, contaminated by GI alone, GII alone, and GI&GII. The HuNoVs prevalence of shellfish in Europe, America, and Asia was 33% (95% CI: 24–43), 24% (95% CI: 7–47), and 27% (95% CI: 18–35), respectively, while only 10% (95% CI: 5–17) in Africa. Furthermore, the prevalence of HuNoVs in shellfish was the highest in spring (35%, 95% CI: 23–49) and winter (35%, 95% CI: 22–50), and the lowest in summer (11%, 95% CI: 5–18). Oysters, clams, and mussels had comparable HuNoVs prevalence of 28% (95% CI: 20–37), 27% (95% CI: 16–39) and 24% (95% CI: 17–32), respectively. The prevalence of HuNoVs in shellfish from harvest areas and markets was 30% (95% CI: 23–38) and 30% (95% CI: 19–41), respectively. The results of this study suggest a substantial burden of HuNoVs in shellfish worldwide, with GII.4 (92.86%) and GII.2 (46.43%) as the predominant genotypes. This study provides information regarding the contamination of HuNoVs in shellfish worldwide, which will contribute to the development of appropriate control measures to prevent shellfish-related HuNoVs gastroenteritis. • The pooled prevalence of human noroviruses in shellfish was found as 29% (95% CI: 23–35) worldwide. • GII.4 (92.86%, 26/28) was found as the most common genotype in shellfish. • Significant differences were found in the seasonal and geographical prevalence of human noroviruses in shellfish. [ABSTRACT FROM AUTHOR]

Oysters and mussels are important vectors for norovirus (NoV). An efficient pretreatment method for NoV detection in oysters based on ISO 15216-2:2019 was established in our previous work, but its effectiveness for other types of shellfish remains unknown. Therefore, this study systematically compared the differences between the standard and modified ISO methods in detecting NoV for oysters and mussels. Using the standard ISO method, the recovery rates of NoV in oysters (2.10 ± 0.80 %) and mussels (2.39 ± 0.56 %) were comparable (p > 0.05, unpaired t -test). In contrast, the virus recovery rates in oysters (19.83 ± 3.64 %) and mussels (46.96 ± 3.55 %) were both significantly improved by the modified method. Also, a significant difference was found between the virus recovery rates in two shellfish (p < 0.05, unpaired t -test), resulting in a 2.09-fold difference in their virus concentrations. Additionally, the limits of detection at 95 % probability of the modified ISO method for oysters and mussels could both reach 3.33 × 103 copies/g of digestive glands. Finally, the modified ISO method has been successfully applied in commercial oysters (14/27, 51.85 %) and mussels (15/23, 65.22 %), and the results indicated a significant difference in NoV recovery rates between two shellfish (p < 0.05, one-way analysis of variance). In summary, the modified ISO method showed higher virus recovery rates than the standard ISO method, which would be used as an essential tool for NoV detection in oysters and mussels. • We developed a new method that improves viral detection in oysters and mussels. • Our method provided a higher virus recovery rate than the standard ISO method. • There were significant differences in virus recovery between oysters and mussels using the new method. [ABSTRACT FROM AUTHOR]

In this paper, we propose a finite-strain plate theory to study the growth-induced deformations and instabilities of multi-layered hyperelastic plates. First, under the assumption of plane-strain deformation, we formulate the governing system for a multi-layered hyperelastic (neo-Hookean) plate. The layers in the plate have different geometrical, material and growth parameters. Starting from the governing system, we propose a scheme to establish the plate equation system, where one arbitrary layer is selected as the base layer and a series-expansion approach is adopted. Through a complicated derivation procedure, the iteration relations of the unknowns in the different layers are obtained, and then the plate equation system containing the unknowns in the base layer are derived, which can attain the accuracy of O (h 2). To show the efficiency of the plate equations, we first study the growth-induced bending deformations of a multi-layered hyperelastic plate. By solving the plate equations, some analytical results are obtained, which provide accurate predictions on the deformations of the plate. The influences of the geometrical and material parameters on the response of the plate are also investigated. Besides that, the plate equation system is applied to study the growth-induced instabilities of a 3-layered hyperelastic plate. Through some conventional analyses, the critical values of the growth parameters corresponding to the different bifurcation modes are determined, which can fit the numerical results very well. In our opinion, the plate theory proposed in the current work is helpful for the design of intelligent soft devices with multi-layered plate forms. [Display omitted] • A finite-strain plate theory for growth of multi-layered hyperelastic plate is established. • The scheme for deriving the plate equations from the original governing system is proposed. • Some analytical results are obtained for growth-induced bending deformations of plates. • The instability of a 3-layered plate is studied based on the plate equations. • The obtained analytical results can fit the numerical results very well. [ABSTRACT FROM AUTHOR]

• Non-epidemic norovirus genotype GII.8 virus-like particles (VLP) were expressed using the baculovirus-insect cell system. • Binding of GII.8 VLP to tissue blood group antigens (HBGAs) was observed. • The cross-reactivity of GII.8 VLP antiserum with other 27 (9 GI genotypes and 18 GII genotypes) capsid protein was evaluated. • Norovirus GII.8 strain antiserum had no cross-blocking effect on the binding of epidemic genotypes (GII.4, GII.17) to HBGA. • The existing vaccine candidate strain GI.1 antiserum and GII.4 antiserum had no cross-blocking effect on the binding of NoV GII.8 to HBGA. Noroviruses are causative agents of acute nonbacterial gastroenteritis epidemics worldwide. There are various genotypes, among which the non-epidemic genotype GII.8 can cause norovirus outbreaks. We previously demonstrated that the immunogenicity of GII.8 differed from that of epidemic variants. This study aimed to comprehensively compare the receptor profile and immunogenicity of the GII.8 variant with those of the epidemic variants. Using the baculovirus-insect cell expression system, we observed that recombinant capsid protein VP1 of the norovirus GII.8 GZ2017-L601 strain formed virus-like particles (VLPs) with a diameter of approximately 30 nm, as evidenced by transmission electron microscopy analysis. The GII.8 VLPs showed weak or moderate binding with all secretor histo-blood group antigens (HBGAs), but not with non-secretors, as evidenced by the HBGA-VLP binding test. The GII.8 VLP antiserum obtained from immunized BALB/c mice was tested for cross-reactivity with other norovirus genotypes (n = 28). The results showed that this antiserum demonstrated moderate cross-reactivity with GI.1, GII.3, and GII.15; however, no cross-reactivity with the epidemic variants of GII.2, GII.4, and GII.17 was observed. Additionally, the blocking-antibody activity of GII.8 antisera against GII.4 VLP-HBGAs and GII.17 VLP-HBGAs interactions and the cross-blocking of GII.8 VLP-HBGAs interactions by GI.1 and GII.4 antisera were evaluated using the HBGAs-VLP blocking test. However, no cross-blocking effect was observed. In summary, the characterization of norovirus GII.8 VLPs and derived antisera revealed that the GII.8 immunogenicity differed from that of epidemic variants. [ABSTRACT FROM AUTHOR]