线性代数与空间解析几何教学内容改革实践

科学技术的发展深刻地影响着大学教育体系和教育模式 ,大学教育的改革势在必行 ,面向二十一世纪高等数学教学改革是高等教育改革中一个非常重要的组成部分 ,线性代数与空间解析几何是高等数学的三大模块之一 ,本文主要介绍面向二十一世纪高等数学教学改革教材《线性代数与空间解析几何》教学内容的改革实践 .     

激光等离子体研究中的X光背景照明诊断技术

给出X光背景照明诊断系统选取主靶、附靶、X光滤片系列的基本物理设计和初步实验结果。在调试X光背景照明激光束与两束主激光束精密时间同步过程中采用了快速扫描可见光条纹相机与光纤相结合的技术,提高了等光程测量效率。初步调试三束激光时间同步精度为15—20ps。     

碱熔-离子色谱法同时测定植株中氯和硫的含量

样品采用氧化镁-碳酸钠混合熔剂,在恒温马弗炉中800℃加热1h,冷却,用水超声浸提.用碱融-离子色谱法同时测定植株中氯和硫的含量.分析柱:AS14A 4-mm(4×250mm),淋洗液:8.0mmol/L Na2CO3-1.0mmol/L NaHCO3,再生液:50mmol/L H2SO4,流速:1.0mL/min,进样体积:20μL,外标峰面积定量.Cl在0.2-30μg/mL,S在3-100μg/mL浓度范围内具有良好的线性关系.平均回收率Cl为96.95%;S为93.56%.相对标准偏差Cl为1.16%;S为1.42%.实验证明该方法操作简便、快速灵敏、准确.     

A novel approach for the preparation of organic-siloxane oligomers and the creation of hydrophobic surface

In this paper, poly(acrylate-g-siloxane) with novel comb-like structure was designed and prepared so as to create a strongly hydrophobic polymer surface. In order to achieve this goal, a series of organic-siloxane oligomers with different chain lengths and a double bond were firstly synthesized through the catalytic reforming and hydrosilylation reaction. Then, poly(acrylate-g-siloxane) was prepared by the copolymerization of the resulting oligomers with acrylate via emulsion polymerization. The as-synthesized oligomers were characterized by ¹H NMR and UV spectrometry, and the morphologies and surface chemical compositions of the dried membrane were investigated by FT-IR, XPS, as well as AFM. XPS analysis result shows that the chemical composition of the membrane's surface was rich in polysiloxane segments, which could be responsible for an increase of surface water repellency (the contact angle could reach 115° at a lower content of polysiloxane). A further investigation suggest that the side chain length of siloxane in the poly(acrylate-g-siloxane) was the dominant factor in influencing the hydrophobicity of the membrane’ surface. When the siloxane chain length reaches to eight, the membrane's surface could exhibit the strongest hydrophobicity.     

钛酸锶单晶体生长工艺研究

使用数控焰熔法晶体生长炉生长钛酸锶单晶体,研究了气体参数、生长速度和退火工艺参数对晶体生长的影响.在氢氧比为2.5,等径生长速度保持在10 mm·h-1,生长出了直径26 mm、等径长度20 mm、总长40 mm的钛酸锶单晶体,然后经过1550℃ ×72 h+1000℃ ×20 h+600℃ ×24 h的退火,消除钛酸锶单晶体的热应力和氧空位,得到完整的高品质的单晶体.偏光显微镜测试表明,晶体具有很好的完整性.     

提拉法生长直径8inch Yb∶YAG激光晶体

设计制造了适于生长直径8 inch Yb∶YAG激光晶体的生长系统和热场,采用感应加热提拉法成功生长出了直径8英寸Yb∶YAG激光晶体,晶体等径部分最小直径202 mm,等径长超过215 mm,总重63.7 kg,晶体外形完整,内部无气泡、包裹物、开裂等宏观缺陷,5 mW绿光激光照射下,未见散射颗粒.     

等离子体改性CuO/γ-Al_2O_3催化剂催化低浓度甲烷燃烧性能

为了研究CuO/γ-Al_2O_3催化低浓度甲烷燃烧性能,采用普通浸渍法和低温等离子体改性的方法分别制备了CuO/γ-Al_2O_3和CuO/γ-Al_2O_3-P催化剂,并用于低浓度甲烷燃烧,考察了Cu负载量和等离子体改性工艺对其催化活性的影响。结果表明,Cu负载量为7%时,催化剂的活性最强。改性气体、气体空速、放电电压、放电频率、等离子体处理时间均是影响催化剂活性的因素。氧气适合用作催化剂的改性气体,而氮气不宜作为改性气体使用。氧气作为改性气体时,最佳的改性工艺条件为峰峰值电压45 kV、放电频率14.71 kHz、等离子体处理时间30 min、氧气空速20 mL/(min·g)。在此工艺条件下制备的催化剂用于低浓度甲烷催化燃烧,可使t10降低23℃、t50降低6℃、t90降低19℃,同时,可使反应的活化能由79.27 kJ/mol降低为76.12 kJ/mol。催化剂的SEM、BET、XRD、XPS、H_2-TPR表征结果表明,等离子体对催化剂的改性作用主要在于增大了催化剂的比表面积、促使催化剂中Cu周围电子云密度降低及体相氧向表面氧迁移,从而利于甲烷在催化剂表面的吸附、活化和转化。     

Facile synthesis of C-decorated Fe,N co-doped TiO2 with enhanced visible-light photocatalytic activity by a novel co-precursor method

Lattice-doping and surface decoration are prospective routes to improve the visible-light photocatalytic ability of TiO₂, but the two techniques are difficult to combine into one preparation process because they are usually conducted under different conditions, which limits the efficiency of TiO₂ modification. In this study, TiO₂ was successfully modified by simultaneous lattice-doping and surface decoration, and the visible-light photocatalytic capacity was largely improved. Upon comparing the method reported here with previous ones, the most significant difference is that Fe(II)-phenanthroline was first used as the co-precursor of the introduced elements of C, N, and Fe. These three elements were simultaneously introduced to TiO₂ at high levels by this co-precursor method. The as-synthesized photocatalysts were systemically investigated and analyzed by several characterization methods such as XRD, FT-IR, XPS, Raman spectroscopy, EPR, UV-Vis DRS, photoluminescence spectra, photocurrent, electrochemical impedance spectra, TEM, and HRTEM. The photocatalytic degradation of 4-NP under visible-light irradiation was used to evaluate the photocatalytic activity of the photocatalysts. Based on the experimental data, a probable mechanism for the photocatalytic degradation by the photocatalysts is proposed. This is a novel method of using one source to simultaneously introduce metal and non-metal elements to TiO₂ at high levels, which may provide a new way to prepare highly effective TiO₂ photocatalysts.     

A New Pyrone Derivative from Fungus Cephalosporium sp. AL031

Cephalosporium sp. AL031 is a fungus isolated from Sinarundinaria nitida grown in the Ailao Mountain, Yunnan, China. It produces, in cultures, antibacterial and fungicidal secondary metabolites, according to the antimicrobial activity test1. In previous p…     

室温液相还原法制备纳米Pt/Al2O3催化剂及其催化性能的研究

在室温条件下利用甲醛还原法，制备了Pt粒径可控纳米颗粒并担载于γ-Al2O3载体上的Pt／γ-Al2O3催化剂．利用甲醇重整反应为探针反应．考察了Pt粒径与催化反应性能之间的关系，发现催化反应的性能与担载贵金属粒径之间存在明显的相关性．结合透射电镜(TEM)表征结果与甲醇水蒸气重整(SRM)性能．发现纳米Pt的粒径大小不但影响甲醇重整反应的活性．同时也影响反应的选择性，即催化剂的性质与担载贵金属粒径之间存在明显的尺度效应．