纳米羟基磷灰石/羧甲基壳聚糖多孔生物复合材料的制备与性能研究

采用化学沉淀法合成了纳米羟基磷灰石粉体(HAP),以无水乙醇为沥滤剂,以16.7%(质量分数)的柠檬酸水溶液作粘结剂,通过粒子沥滤法制备了HAP/CMCS多孔材料,并对其进行了IR、XRD、SEM、孔隙率及抗压强度的测试。结果表明HAP/CMCS复合材料复合前后两组份的化学组成未发生显著变化,但两相间发生了相互作用。多孔材料孔隙率高,孔径分布范围宽,其尺寸分布大约从几微米到600微米,以圆形为主,具有良好的贯通性,非常有利于组织在其中的长入与扩展。当复合材料中CMCS含量为40%,复合材料/造孔剂的质量比为1:1时,多孔材料的孔隙率接近75%,其抗压强度可达21MPa以上,可以满足骨组织工程支架材料的要求。     

工作气压对磁控溅射ITO薄膜性能的影响

工作气压在ITO薄膜的制备过程中是一个重要的工艺参数,直接决定着薄膜的性能.本文利用射频磁控溅射方法,采用氧化铟锡陶瓷靶材,在衬底温度为175℃,工作气压范围为0.45～1.0 Pa条件下,制备了氧化铟锡透明导电薄膜.研究了工作气压对其微观结构、表面形貌和光电特性的影响.在衬底温度为175℃、纯氩气中制备的氧化铟锡薄膜电阻率为3.04 ×10-4 Ω·cm、可见光波段(400～800 nm)透过率为91.9;,适合用作异质结太阳电池的前电极和减反射膜.     

低温制备≥99.5%多晶氧化铝陶瓷

本文通过引入稀土氧化物Y2O3、Tm2O3为烧结助剂低温制备了氧化铝含量大于99.5;的多晶氧化铝陶瓷.实验表明:稀土氧化物的加入能够明显降低99.5;多晶氧化铝陶瓷的烧结温度,提高致密度.Y2O3、Tm2O3混合烧结助剂与单一稀土氧化物的烧结助剂相比能够明显抑制晶粒的生长,促进晶粒的均匀发育.当Y2O3+Tm2O3的含量为0.3;质量分数时,99.5;多晶氧化铝陶瓷的相对密度可达99.2;理论密度,抗弯强度为533MPa,显微硬度为17.2GPa.陶瓷断裂主要以穿晶断裂为主.     

Fe3+对KDP晶体光学质量的影响

金属离子Fe3+对KDP晶体的生长和光学性质有明显影响.本文在前期研究的基础上[1]系统考察了该杂质离子对KDP晶体光学质量的影响.实验结果表明,三价金属离子Fe3+会降低KDP晶体的透光率,同时对晶体均匀性和光损伤阈值也有明显影响.光损伤阈值降低的主要原因在于杂质诱发缺陷导致的电子崩电离、多光子电离(尤其是双光子电离)等过程的发生.     

退火温度对6H-SiC衬底上ZnO薄膜发光性质的影响

采用溶胶-凝胶方法,在6H-SiC衬底上制备ZnO薄膜.X射线衍射结果表明薄膜是c轴取向的,具有六方纤锌矿多晶结构.研究了退火温度对ZnO薄膜发光特性的影响.发现在650℃退火温度下,观察到近带边紫外发射和可见光发射并且紫外发光强度大于可见光发射.随着退火温度的提高,紫外峰强度减弱直至消失,而绿光发射强度先增加而后降低.对退火温度引起ZnO薄膜发光性质改变的机制进行了探讨.     

Synthesis, Crystal Structure and Biological Activity of Novel Dichloroacetyl Oxazolidine Herbicide Safeners

A series of novel N-dichloroacetyl oxazolidine herbicide safeners was synthesized and characterized by IR, 1H NMR, 13C NMR, elemental analysis and X-ray diffraction. The preliminary biological test shows that the compounds could protect maize against injury caused by chlorsulfuron to a certain extent.     

Packed-Fiber Solid Phase-Extraction Coupled with HPLC-MS/MS for Rapid Determination of Lipid Oxidative Damage Biomarker 8-Iso-Prostaglandin F2α in Urine

The 8-iso-prostaglandin F_2α (8-iso-PGF_2α) biomarker is used as the gold standard for tracing lipid oxidative stress in vivo. The analysis of urinary 8-iso-PGF_2α is challenging when dealing with trace amounts of 8-iso-PGF_2α and the complexity of urine matrixes. A packed-fiber solid-phase extraction (PFSPE)–coupled with HPLC-MS/MS–method, based on polystyrene (PS)-electrospun nanofibers, was developed for the specific determination of 8-iso-PGF_2α in urine and compared with other newly developed LC-MS/MS methods. The method, which simultaneously processed 12 samples within 5 min on a self-made semi-automatic array solid-phase extraction processor, was the first to introduce PS-electrospun nanofibers as an adsorbent for the extraction of 8-iso-PGF_2α and was successfully applied to real urine samples. After optimizing the PFSPE conditions, good linearity in the range of 0.05–5 ng/mL with R² > 0.9996 and a satisfactory limit of detection of 0.015 ng/mL were obtained, with good intraday and interday precision (RSD < 10%) and recoveries of 95.3–103.8%. This feasible method is expected to be used for the batch quantitative analysis of urinary 8-iso-PGF_2α.     

Cloning,Expression, Purification,and Characterization of β-Galactosidase from Bifidobacterium longum and Bifidobacterium pseudocatenulatum

Expression and purification of β-galactosidases derived from Bifidobacterium provide a new resource for efficient lactose hydrolysis and lactose intolerance alleviation. Here, we cloned and expressed two β-galactosidases derived from Bifidobacterium. The optimal pH for BLGLB1 was 5.5, and the optimal temperature was 45 °C, at which the enzyme activity of BLGLB1 was higher than that of commercial enzyme E (300 ± 3.6 U/mg) under its optimal conditions, reaching 2200 ± 15 U/mg. The optimal pH and temperature for BPGLB1 were 6.0 and 45 °C, respectively, and the enzyme activity (0.58 ± 0.03 U/mg) under optimum conditions was significantly lower than that of BLGLB1. The structures of the two β-galactosidase were similar, with all known key sites conserved. When o-nitrophenyl-β-D-galactoside (oNPG) was used as an enzyme reaction substrate, the maximum reaction velocity (V_max) for BLGLB1 and BPGLB1 was 3700 ± 100 U/mg and 1.1 ± 0.1 U/mg, respectively. The kinetic constant (K_m) of BLGLB1 and BPGLB1 was 1.9 ± 0.1 and 1.3 ± 0.3 mmol/L, respectively. The respective catalytic constant (k_cat) of BLGLB1 and BPGLB1 was 1700 ± 40 s⁻¹ and 0.5 ± 0.02 s⁻¹, respectively; the respective k_cat/K_m value of BLGLB1 and BPGLB1 was 870 L/(mmol∙s) and 0.36 L/(mmol∙s), respectively. The K_m, k_cat and V_max values of BLGLB1 were superior to those of earlier reported β-galactosidase derived from Bifidobacterium. Overall, BLGLB1 has potential application in the food industry.     

出境旅游网络关注度时空演变及影响因素研究——以泰国为例

网络关注度是测量潜在旅游者对目的地旅游关注情况及需求变化的重要手段之一。基于百度指数,以我国31个省（区、市）（不含港、澳、台）的泰国旅游网络关注度为研究对象,运用季节性强度指数、地理集中度指数、赫芬达尔-赫希曼指数、地理探测器等方法,探讨我国居民对泰国旅游网络关注度的时空演化规律及其影响因素。结果表明：从时序演化上看,2011—2019年泰国旅游网络关注度呈波动上升态势,可划分为快速上升期和平稳发展期2个阶段,地区季节性差异显著,3月、7月、12月为泰国旅游网络关注度的高峰时段;从空间分异上看,泰国旅游网络关注度空间分异变化不大,空间集聚趋于分散状态,整体呈“东高-西低”的阶梯状递减特征,高关注度地区主要集中在东部地区及四川省,低关注度地区则主要分布于除四川省外的西部省份;从影响因素上看,经济发展水平（人均可支配收入、GDP）、交通便利程度、贸易开放度以及国际旅游开放度共同影响泰国旅游网络关注度的空间分布格局。     

高效液相色谱法和硫氰酸钾滴定法检测煤中氯的比较研究

比较了测定煤中氯的高效液相色谱(HPLC)法和硫氰酸钾滴定法。以密闭氧弹燃烧或艾氏卡剂熔融分解样品，分别以高效液相色谱法和硫氰酸钾滴定法测定煤中氯，通过对国家标准物质GBW11118、GBW11119、GBW11120分析结果的比较及t检验，表明两方法无显著性差异。