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IntroductionThe irrational use of antibiotics has facilitated the emergence of multidrug- resistant Shigella spp., undermining the effectiveness of the currently available antibiotics. Consequently, there is an urgent need to explore new approaches, with phage therapy emerging as a promising alternative.MethodsIn this study, we isolated a phage targeting Shigella dysenteriae from sewage samples using DLA methold, designated Henu10. The morphology, biological characteristics, genomic composition, and phylogenetic relationships of Henu10 were thoroughly characterized. To investigate the trade-off relationship between phage resistance and bacterial fitness, phage Henu10-resistant strains R6 and R11 were identified using continuous passage and bidirectional validation methods.ResultsPhage-resistant strains R6 and R11 exhibited impaired adsorption, increased sensitivity to temperature and pH stress, heightened susceptibility to certain antibiotics (such as ciprofloxacin and kanamycin), reduced biofilm-forming capacity, and diminished colonization ability in vivo compared to the wild-type strain.DiscussionThese results indicate that phage Henu10 may effectively control the pathogenic bacteria associated with S. dysenteriae, representing a promising new therapeutic option for treating S. dysenteriae infections.

The collision and friction between the rock masses during the caving of the gob roof has become an important hidden danger to induce the gas explosion accident in the gob. In order to study the mechanism of gas explosion induced by sandstone friction by friction velocity, friction force, gas concentration, SiO2 content and other factors, the rock friction effect igniting gas test system was used to conduct quantitative test research on each factor. The results show that when the gas concentration is 7.0%-11.5%, the gas explosion time induced by sandstone friction first decreases and then increases with the increase of gas concentration. The high friction and hot surface of sandstone is the main cause of gas explosion. Gas explosion induced by friction can be divided into two stages: gas burning on sandstone friction surface and gas explosion diffusion. The time of gas explosion induced by friction decreases with the increase of friction and the increase of SiO2 content in sandstone. When the friction is lower than the minimum critical velocity, the gas explosion will not be induced. When the friction is higher than the minimum critical velocity and lower than the maximum critical velocity, the maximum friction velocity is negatively correlated with the gas explosion time.

Phytoplankton community structure based on photosynthetic pigments in the Lembeh strait was studied in April 2017, during the period of monsoon transition. With data of the spatial distribution of phytoplankton community structures and environmental factors, the main factors leading to the changes in phytoplankton community structure and distribution of phytoplankton abundance were discussed. Our results show that the phosphate concentration in the north of the strait was higher than that in the south, while the distribution of nitrogen concentration was just the opposite. The silicate concentration had a significance high concentration in the bottom water of the northern strait, indicating that there was a sinking ocean current from the north. Different from previous surveys, the N/P ratio of water ranges from 2.6 to 4.56, proving that nitrogen is the nutrient limiting factor in this survey, which was due to increased phosphorus concentrations due to continuous heavy rains. The main pigments were Chl b, 19-hex-fucoxanthin and fucoxanthin during the period of monsoon transition. Chl a concentration was significantly higher in the north of the strait than in the south, and Chl a concentration at surface was higher than that at bottom. This is because the thrive of cyanobacteria in the northern strait, which were the main group in the Lembeh strait during monsoon transition. They can grow and reproduce in the nutrient-poor sea water, since they can use phosphonates as a source of phosphorus during metabolic processes. Compared with surveys conducted during SE monsoonal period, the abundance of phytoplankton in monsoon transition period was significantly lower. Because the upwelling brought sufficient nutrients to the water, which meet the require of phytoplankton growth, allowing phytoplankton to grow well in SE monsoon. On the whole, the results show that the changes in phytoplankton community structure and distribution of phytoplankton abundance during the monsoon transition period in the Lembeh strait is mainly affected by nutrients. Keywords: Photosynthetic pigments, Phytoplankton, Community structure, Monsoon transition, Lembeh strait

Abstract Background Antenatal depression (AD) is considered as one of the major health burdens and has adverse effects on the outcome of expectant mothers and newborns. The present study aims to investigate the prevalence of antenatal depression (AD), and to explore the potential risk factors of AD among pregnant women in Chengdu, including personal background, related social factors, family factors and cognitive factors. Methods The prospective nested case-control study included pregnant women who were in their second pregnancy and attended prenatal care at three tertiary hospitals and one regional hospital in Chengdu, China, between March 2015 and May 2016. Self-designed questionnaires were given to participants in their second and third trimesters to collect information on clinical and demographic characteristics, and a modified edition of Edinburgh Postnatal Depression Scale (EPDS) were used to measure AD. The logistic regression was applicated in analyses. Results A total of 996 pregnant women were included in analysis. Ninety-three women suffered from AD symptoms only in their second trimester, 96 only in their third trimester, and 107 displayed persistent depression in both trimesters. In the univariate analyses, age and marital relationships were linked with AD occurrence in both second and third trimester. In addition, increasing age, full-time job, higher education level, and no gender preference of spouse were associated with reduced persistent depression. Multivariate analysis showed that gender preference and marital relationship were the potential risk factors of persistent depression. Conclusions Age, marital relationship relationships, with parents-in-law, the negative recognition of this pregnancy and husband’s gender preference were found as risk factors of AD occurrence in some specific trimester. Gender preference of husbands and marital relationships were independently associated with persistent depression. These findings suggest that stronger family support can help improve mental health of pregnant women.

Adhesives typically fall into two categories: those that have high but irreversible adhesion strength due to the formation of covalent bonds at the interface and are slow to deploy, and others that are fast to deploy and the adhesion is reversible but weak in strength due to formation of noncovalent bonds. Synergizing the advantages from both categories remains challenging but pivotal for the development of the next generation of wound dressing adhesives. Here, we report a fast and reversible adhesive consisting of dynamic boronic ester covalent bonds, formed between poly(vinyl alcohol) (PVA) and boric acid (BA) for potential use as a wound dressing adhesive. Mechanical testing shows that the adhesive film has strength in shear of 61 N/cm² and transcutaneous adhesive strength of 511 N/cm², generated within 2 min of application. Yet the film can be effortlessly debonded when exposed to excess water. The mechanical properties of PVA/BA adhesives are tunable by varying the cross-linking density. Within seconds of activation by water, the surface boronic ester bonds in the PVA/BA film undergo fast debonding and instant softening, leading to conformal contact with the adherends and reformation of the boronic ester bonds at the interface. Meanwhile, the bulk film remains dehydrated to offer efficient load transmission, which is important to achieve strong adhesion without delamination at the interface. Whether the substrate surface is smooth (e.g., glass) or rough (e.g., hairy mouse skin), PVA/BA adhesives demonstrate superior adhesion compared to the most widely used topical skin adhesive in clinical medicine, Dermabond. [ABSTRACT FROM AUTHOR]

We describe the materials, design, experimental measurements, and simulations of a bio-inspired all-solid tunable optical device: ionic eye. A dielectric elastomer functions as an electroactive material. An ionogel functions as an ionic conductor. Both materials are stretchable and transparent. The ionic eye achieves a ~50% relative change of the focal length, beyond that of the human eye. Our analysis also points out that the ionic eye can respond rapidly (3.6 ms) and be miniaturized in size. This all-solid deformable lens eliminates the risk of leakage of currently used encapsulated fluid lenses and can be integrated into other devices for diverse applications. [ABSTRACT FROM AUTHOR]

Soft ionic conductors have enabled stretchable and transparent devices, but liquids in such devices tend to leak and evaporate. In this study, we demonstrate diodes and transistors using liquid-free ionoelastomers, in which either anions or cations are fixed to an elastomer network and the other ionic species are mobile. The junction of the two ionoelastomers of opposite polarity yields an ionic double layer, which is capable of rectifying and switching ionic currents without electrochemical reactions. The entropically driven depletion of mobile ions creates a junction of tough adhesion, and the stretchability of the junction enables electromechanical transduction. [ABSTRACT FROM AUTHOR]

Polyacrylamide hydrogels containing salt as electrolyte have been used as highly stretchable transparent electrodes in flexible electronics, but those hydrogels are easy to dry out due to water evaporation. Targeted, we try to enhance water retention capacity of polyacrylamide hydrogel by introducing highly hydratable salts into the hydrogel. These hydrogels show enhanced water retention capacity in different level. Specially, polyacrylamide hydrogel containing high content of lithium chloride can retain over 70% of its initial water even in environment with relative humidity of only 10% RH. The excellent water retention capacities of these hydrogels will make more applications of hydrogels become possible. [ABSTRACT FROM AUTHOR]

Pure shear experiments are commonly used to characterize dielectric elastomer (DE) material properties and to evaluate DE actuator/generator performance. It is increasingly important for many applications to replace conventional carbon grease electrodes with stretchable elastomeric conductors. We formulate a theory for DE with elastomeric conductors, synthesize transparent hydrogel as ionic conductors, and measure actuation of DE in pure shear deformation. Maximum 67% actuation strain is demonstrated. The theory agrees well with our measurement and also correlates well with reported experiments on DE with electronic conductors. [ABSTRACT FROM AUTHOR]

Hydrogels containing electrolyte can work as ionic conductors to actuate dielectric elastomer (DE) artificial muscles. Based on a popular design of a circular actuator, we study theoretically and experimentally the cyclic performance of acrylic DE actuators with solid hydrogel electrodes. The viscoelasticity of solid electrodes constrains the maximum strain that is attainable for one cycle of triangular voltage, and it also diminishes the accumulated increment of the maximum strain after many cycles of loadings. [ABSTRACT FROM AUTHOR]

Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious: large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content. [ABSTRACT FROM AUTHOR]