Enhanced energy storage performance of nanocomposites filled with paraelectric ceramic nanoparticles by weakening the electric field distortion

Polymer-based dielectric nanocomposites, which combines the high dielectric constant of ceramic materials and the high breakdown strength of polymer materials, has emerged as one of the most effective progress for the advanced dielectric energy storage materials. To improve energy storage performance, the core-shell structured SiO₂@SrTiO₃ paraelectric nanoparticles are used as fillers in constructing the polymer-based nanocomposites. Hence, this paper systematically investigates the impacts of filler content on energy storage performance and breakdown strength, and provides insight into the polarization behavior of different composites filled with paraelectric and ferroelectric nanoparticles (SiO₂@BaTiO₃), respectively. Combined finite element simulations, it is shown that the dielectric constant of the paraelectric ceramic is more similar to the polymer matrix, resulting in weakening the electric field distortion in the dielectric. Furthermore, due to the paraelectric characteristics of SrTiO₃ nanoparticles and the diminution of interface polarization, the remnant polarization of the nanocomposites can be significantly reduced. The polymer-based dielectric nanocomposites exhibit more impressive energy storage, of 11.42 J/cm³ at 350 MV/m with 2.5 vol% paraelectric SiO₂@SrTiO₃ nanoparticles, which is superior to the composite filled with ferroelectric nanoparticles. Overall, this finding not only establishes a new direction for the structural design of fillers but also provides insight into an underlying mechanism to control interface polarization in the dielectric composites.     

An effective method to screen carbon (boron,nitrogen) based two-dimensional hydrogen storage materials

The current critical environmental pollution caused by the huge fossil fuel burning together with the increasingly scarce energy source has inspired much attention on the renewable clean hydrogen energy. Thus, the hydrogen storage materials are very vital for the hydrogen application and will be screened by the high-throughput computational screening procedure in this paper. Generally, metal-modified carbon (boron, nitrogen) nanomaterials can exhibit excellent hydrogen storage capacities. An effective procedure is designed to screen the potential metal decorated carbon (boron, nitrogen) hydrogen storage materials from the Materials Project database, which can be proved to be easily realized and reliable. Totally six ideal structures are obtained for hydrogen storage by considering the thermodynamic stability, the metal decorating, the theoretical hydrogen gravimetric density larger than 5.5 wt%, the PBE band gap smaller than 1.0 eV, and the two-dimensional structure restriction. Furthermore, the binding energy of the metal atom to the screened 2D materials, the average adsorption energy per H₂ adsorbed by the metal, the density of states, the difference charge densities are calculated by the density functional method. We believe that our screening procedure can effectively and accurately search for hydrogen storage materials, which should be the theoretical basis for experimental researches.     

A Green Strategy to Synthesize Ag/Ag3PO4/Chitosan Composite Photocatalysts and Their Photocatalytic Degradation Performance under Visible Light Irradiation

In this work, the plasmonic Ag/Ag₃PO₄/chitosan (Ag/Ag₃PO₄/CS) composite photocatalyst was prepared by a low-temperature strategy. Environmentally friendly CS plays triple vital roles in this composite. First, it was devoted to in situ reducing metallic silver from silver ions of Ag₃PO₄. Also, as the carrier of Ag/Ag₃PO₄ nanoparticles, CS can effectively prevent aggregation. Furthermore, benefitting from the settlement of hydrophilic CS, the prepared composite could be easily separated and recovered from the solution system. X-ray diffraction (XRD), the scanning electron microscope, energy-dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-vis) diffused reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to characterize the properties of materials. The results of photo-decomposition testing showed that the Ag/Ag₃PO₄/CS composite possessed good activity for the decomposition of Rhodamine B (RhB) under visible light.     

秭归地区鲊广椒中乳酸菌及细菌多样性研究

该研究在采用纯培养方式对秭归地区鲊广椒中乳酸菌进行分离鉴定的基础上，进一步采用MiSeq高通量测序技术对其细菌多样性进行解析。结果表明，从14个鲊广椒中分离出的43株疑似乳酸菌被鉴定为乳酸杆菌属（Lactobacillus）和屎肠球菌属（Enterococcus），鉴定到的种主要有植物乳杆菌（Lactobacillus plantarum）、敏捷乳杆菌（Lactobacillus alimentarius）和屎肠球菌（Enterococcus faecium），占所有分离株的86.05%，其中L. plantarum占所有分离株的60.74%，为优势菌种。测序结果显示，鲊广椒中主要的细菌类群为隶属于硬壁菌门（Firmicutes）的Lactobacillus和戊糖片球菌属（Pediococcus）以及隶属于变形菌门（Proteobacteria）的假单胞菌属（Pseudomonas），其平均相对含量分别为47.85%、13.29%和21.31%，其中乳酸菌含量累计达61.14%。由此可见，秭归地区鲊广椒中蕴含了较为丰富的乳酸菌资源，但同时也存在Pseudomonas等具有致病性的菌属。     

富硒葡萄中硒多糖的分离纯化及抗氧化活性

本文以克瑞森(小粒)富硒葡萄为原料，通过提取、分离纯化得到硒多糖提取物(selenium polysaccharide,sKGP)，并对其理化性质、结构特征及抗氧化活性进行了研究。采用超声波辅助酶法提取，用二乙氨基乙基交联葡聚糖凝胶A-25(DEAE-SephadexA-25)层析柱分离纯化得到高纯度硒多糖组分，通过紫外光谱、液质、傅里叶红外、扫描电镜等对其活性官能团及其结构进行鉴定，并对其抗氧化活性指标进行了分析。结果表明：sKGP硒含量为(0.642±0.038)mg/kg；纯化后sKGP-3几乎不含核酸、蛋白质等；sKGP-3由鼠李糖、木糖、阿拉伯糖、甘露糖、葡萄糖和果糖组成，摩尔比为0.172:0.743:0.718:0.082:4.540:0.093;sKGP-3具有Se=O、SeH结构和多糖的典型特征峰；sKGP-3主要呈片状和丝状，属于非晶态。体外抗氧化活性评估表明，纯化前sKGP具有比同质量浓度多糖(grape polysaccharide,KGP)更高的抗氧化活性，sKGP的总抗氧化能力为8.499μmol/mL,DPPH自由基、羟自由基、ABTS⁺     

促干剂对热风条件下西梅品质的影响

本研究以西梅为试材，通过自配促干剂（88%碳酸钾、8%乙醇、3%油酸乙酯、1%氢氧化钾）与市售促干剂（绿珠牌、伊兹木牌、新兴牌、翠绿牌促干剂）处理西梅，探究促干剂对果干失水率、果干产品质量、理化特征等的影响。结果表明，自配促干剂与市售促干剂相比，在果干脱水方面具有明显优势，相同条件下自配促干剂处理的果实失水最快，最高可达26.25%；此外，不同促干剂处理西梅后果实的可溶性固形物和可滴定酸含量均有明显增加，自配促干剂处理的效果优于翠绿促干剂；在质构特征方面，干制后的西梅硬度和咀嚼性均有增加，但是自配促干剂处理的西梅干硬度最小，为1034.62 g，弹性和咀嚼性居中，可以给消费者带来较佳的口感；利用自配促干剂处理的西梅干，抗坏血酸、总酚、总黄酮损失最小，分别为25.48 mg/100 g DW、358.54 mg GAE/g、3.61 mg/g；同时DPPH自由基、ABTS+自由基清除能力较高，分别为79.75%、66.79%。综上所述，自配促干剂可以加速西梅的脱水，同时对西梅干的品质具有一定的有保护作用，该研究成果将为西梅干的生产提供指导。     

A novel lattice-embedded ZnO@TiO2(B) nanoflowers promotes photocatalytic production of H2

Traditional surface-to-surface contact heterojunctions suffer from poor stability and low electron-hole separation efficiency, which has become a crucial limiting the further improvement of photocatalytic property. Therefore, improving the combination of heterogeneous materials will become a new attempt. In this work, a novel lattice embedded ZnO@TiO₂(B) nanoflowers was prepared by combining electrodeposition method combined with hot solvent method. The hetero interface of the ZnO@TiO₂(B) nanoflowers is distributed in the phase of TiO₂(B), which drives high-efficiency charge separation. The sample Zn:Ti 1:4 has the highest photocatalytic property, and the H₂ generation efficiency under the full spectrum is 1.695 mmol g^?1 h^?1, which is 3.5 times that of TiO₂(B). After 36 h cycle stability test, its stability is as high as 90%. According to results, the possible mechanism of ZnO@TiO₂(B) photocatalytic hydrogen production is proposed. These findings may provide new strategies for the preparation of high-efficiency heterojunction photocatalysts with special structures.     

Transplantation of BMP-7 gene-transfected bone marrow mesenchymal stem cells for the treatment of spinal cord injury in rats

Background: Spinal cord injury (SCI) is a serious traumatic disease of the central nervous system, and there is currently no effective treatment for SCI because of its complicated pathophysiology. Bone marrow mesenchymal stem cells (BMSCs) have multidirectional differentiation abilities. Our study aims to explore the effects of bone morphogenetic protein 7 (BMP-7)-modified BMSCs transplantation on the repair of SCI in rats. Methods: In this study, a rat spinal cord injury model was established with the modified Allen method. Then, BMSCs transfected with the BMP7 gene were transplanted to treat the spinal cord injury in rats. Forty Sprague-Dawley rats were randomly divided into the sham operation group (sham group), spinal cord injury group (model group), BMSC treatment group (BMSC group) and LV-BMP7-BMSC treatment group (LV-BMP7-BMSC group). The Basso, Beattie, and Bresnahan (BBB) score was used to evaluate the recovery of hindlimb function in the rats. The levels of neurofilament protein NF-200 (NF-200) and glial fibrillary acidic protein (GFAP) were detected by immunofluorescence, RT-PCR and Western blotting. Results: At 14 d, 21 d, and 28 d after treatment, the BBB score of the rats in the LV-BMP7-BMSC group was higher than that of the rats in the model group and BMSC group. The results showed that NF-200 was expressed at the local spinal cord injury site. Compared with that of the sham group, the NF-200 expression level of the BMSC group and LV-BMP7-BMSC group was increased (P < 0.05). The results showed that the mRNA expression levels of NF-200 in the spinal cord tissue of the BMSC group and LV-BMP7-BMSC group were increased compared with those of the sham group (P < 0.05). The western blotting results further confirmed the PCR results. Conclusion: BMP-7 gene-modified BMSC transplantation can promote the repair of spinal cord functions after SCI in rats.