Polyhydroxybutyrate (PHB) Scaffolds as a Model for Nerve Tissue Engineering Application: Fabrication and In Vitro Assay

In this study, we fabricated PHB scaffolds by solid/liquid phase separation method. The properties of fabricated scaffolds were investigated using SEM, DMTA, and DSC. Our studies noticed that for an approach to scaffolds that contain tubular morphology and better mechanical properties, the solution should be frozen near crystallization temperature. For in vitro evaluation, the P19 mouse embryonal cell line was used as a model system. Results notice that cells attach and differentiate to the nerve cell. In vitro assay shows that it is a suitable model for use as a platform for neural tissue engineering applications.     

Thermal Instability and Microstructure of Strontium M-type Hexaferrite Nanoparticles Synthesized by Citrate Approach

The dried gel of SrFe12O19, prepared by citrate approach, was investigated by means of infrared spectroscopy （ IR ）, thermogravimetric analysis （ TG ）, differential scanning calorimetry （ DSC ）, X- ray diffraction（ XRD ） techniques, energy dispersive spectroscopy（ EDS ）, and transmission electron microscopy（ TEM ）. The thermal instability and the thermal decomposition of low-temperature strontium M-type hexaferrite crystallized at about 600℃ were confirmed for the first time by XRD method. The decomposition of the low-temperature strontium M-type hexaferrite took place at about 688.6℃ determined by DSC investigation. The low-temperature strontium M-type hexaferrite nanopartieles were decomposed into SrFeO2.5 with an orthorthombic cell and Fe2O3 with a tetragonal cell as well as possibl α-Fe2O3 . The agglomerated particles with sizes less than 200 nm obtained at 800℃ were plesiomorphous to strontium M-type hexaferrite. The thermally stable strontium M-type hexaferrite nanopartieles with sizes less than 100um cotdd take place at 900 ℃ . Up to 1000 ℃ , the phose transformotion to form strontium M-type hexaferrite was ended, the calcinations with the sizes more than 1μm were composed of α-Fe2O3 and strontium M-type hexaferrite. The method of distinguishing γ-Fe2O3 with a spinel structure from Fe2O3 with tetragonal cells by using powder XRD method was proposed. Fe2O3 with tetragonal cells to be crystallized before the crystallization of thermally stable strontium M-type hexaferrite was confirmed for the first time. The reason why α- Fe2O3 as an additional phase appears in the calcinations is the cationic vacancy of stroutium M-type hexaferrite , SrFe12-x□O19 （0≤x ≤0.5）.     

PEARL HARBOR AND THE INADEQUACY OF CRYPTANALYSIS

American codebreakers achieved remarkable success in solving Japanese codes, but could not prevent the surprise attack on Pearl Harbor because the Japanese never transmitted anything about the attack on the airwaves.     

Regulatory Noncoding and Predicted Pathogenic Coding Variants of CCR5 Predispose to Severe COVID-19

Genome-wide association studies (GWAS) found locus 3p21.31 associated with severe COVID-19. CCR5 resides at the same locus and, given its known biological role in other infection diseases, we investigated if common noncoding and rare coding variants, affecting CCR5, can predispose to severe COVID-19. We combined single nucleotide polymorphisms (SNPs) that met the suggestive significance level (P ≤ 1 × 10⁻⁵) at the 3p21.31 locus in public GWAS datasets (6406 COVID-19 hospitalized patients and 902,088 controls) with gene expression data from 208 lung tissues, Hi-C, and Chip-seq data. Through whole exome sequencing (WES), we explored rare coding variants in 147 severe COVID-19 patients. We identified three SNPs (rs9845542, rs12639314, and rs35951367) associated with severe COVID-19 whose risk alleles correlated with low CCR5 expression in lung tissues. The rs35951367 resided in a CTFC binding site that interacts with CCR5 gene in lung tissues and was confirmed to be associated with severe COVID-19 in two independent datasets. We also identified a rare coding variant (rs34418657) associated with the risk of developing severe COVID-19. Our results suggest a biological role of CCR5 in the progression of COVID-19 as common and rare genetic variants can increase the risk of developing severe COVID-19 by affecting the functions of CCR5.     

澳门总督府今昔——纪念澳门回归十周年

澳门特区政府总部办公室最初是一座民宅，回归前是总督府。它是澳门19世纪豪宅代表之一，见证了澳门葡式民宅由内敛到张扬的转变。同时，作为不同时期的最高权力所在地，建筑对社会及政局的发展作出相应的嬗变，影响了澳门建筑的发展。     

0Cr19Ni9N机座筒锻件的研制

0Cr19Ni9N中由于含有氮元素 ,使锻造性能大幅下降 ,通过多火次 (5～ 10次 )锻造 ,使 8件产品一次性锻造成功。经检验各项性能指标完全符合要求     

生物降解混源油混合比例估算方法

研究生物降解混源油的混合比例时的关键是根据研究对象的降解程度，选择既能抗该降解程度又能有效区分烃源岩贡献的生物标志化合物，作为估算原油生物降解前的混合比例的参数，并通过配比实验检验估算结果的可靠程度。在研究渤海PL19—3油田生物降解混源油的混合比例时，选用源自沙河街组三段和东营组下段烃源岩的典型油样，以三芳甾烷／三芳甲藻甾烷作为参数，用估算法计算了PL19—3—4井(最靠近渤中凹陷)生物降解原油混合比例，东营组下段烃源岩的贡献约占30％，该井以南的PLl9—3—2井、PL19—3-8井和PL19—3—5井东营组下段烃源岩的贡献逐步下降，最低约占10％。图4表3参15     

基于扎根理论的街坊整体开发模式适用条件研究

街坊整体开发模式作为城市片区整体开发模式的典型代表,其产生必然根植于城市开发和城市更新实践基础,是对原有旧的开发模式的一种迭代和扬弃。以深圳前海十九单元03街坊项目为典型案例,基于扎根理论方法深度解析访谈数据,对街坊整体开发模式的适用条件进行分析,总结凝炼了街坊整体开发模式区域、规模、规划、建设时序、制度环境及开发组织六大适用条件。研究结果表明,六大适用条件较完整地覆盖并解答了街坊整体开发模式适应性涉及的关键问题,为深入理解街坊整体开发模式的适应性特征提供了一个研究视角。     

Respiratory bioaerosol deposition from a cough and recovery of viable viruses on nearby seats in a cabin environment

Respiratory bioaerosol deposition in public transport cabins is critical for risk analysis and control of contact transmission. In this work, we built a two-row four-seat setup and an air duct system to simulate a cabin environment. A thermal manikin on the rear left-hand seat was taken as the infected passenger (IP) and “coughed” three times through a cough generator. The deposited viruses and droplets on nearby seats were measured by a cultivation method and microscope, respectively. The effects of seat backrest and overhead gasper jet were studied. Results showed that the number of deposited virus on the front seat was one order of magnitude higher than that on other seats which only contained droplets smaller than 10 µm in diameter. When the backrest was 15 cm higher than the cough, the deposited number of viruses was reduced to 5% of that with the backrest at the same height with the cough. The gasper jet above the IP with a velocity of 1.5 m/s can reduce the deposited viruses to 4% of that with gasper off. It indicates that both the gasper jet and backrest can work as mitigation measures to block the cough jet and protect the nearby passengers.