前驱体改性法制备薄层多孔富氨基的石墨相氮化碳用于光催化降解RhB和光催化制氢

半导体光催化是一种利用半导体将太阳能转换为高能化学能的绿色技术,在可再生清洁能源生产和污染物修复领域有着巨大的应用前景.石墨相氮化碳(g-C3N4)作为一种环境友好的非金属半导体,因其制备工艺简单、来源丰富、热稳定性和化学稳定性好、可见光吸收范围及特殊的电子性能而受到广泛关注.但一般常用氮源前驱体如二氰二胺、三聚氰胺等...     

C(sp3)—H键直接催化硅基化反应研究进展

含C(sp3)—Si键的有机硅化合物在材料科学、药物化学和精细化学品合成等研究领域有着广泛的应用.通过C(sp3)—H的直接催化硅基化形成C(sp3)—Si键具有高的原子经济性和步骤经济性特点,近些年己成为含C(sp3)—Si键的新型有机硅分子合成领域的一个研究热点.详细总结了 C(sp3)—H键直接催化硅基化反应的研...     

硅亲电试剂参与碳硅交叉偶联反应研究进展

有机硅化合物因其特殊的性质而广泛应用于合成化学、材料、药物和农药化学等领域.有机硅化合物通常由亲核取代、烯烃硅氢化和碳氢键直接硅化等方法制备.近年来,通过交叉偶联构建碳硅键合成有机硅烷取得突破性进展,引起合成化学领域研究者的广泛关注和兴趣,成为有机硅化合物合成研究热点.主要从硅亲电试剂参与的Heck反应、Negishi...     

无机杂化脂肪酶的制备及其催化性能研究

采用脂肪酶为有机组分,Ca2+、Zn2+、Mn2+和Cu2+等4种金属磷酸盐为无机组分,制备脂肪酶-无机杂化纳米花,系统研究4种杂化脂肪酶的结构和催化活性。结果表明,制备的杂化脂肪酶具有花状的层级片状结构,并探究了无机杂化脂肪酶的最优反应时间为10 min,反应温度为40 ℃,pH为8。4种金属离子制备的杂化脂肪酶包封率达到90%以上。相比于游离脂肪酶,杂化脂肪酶的催化水解活性、催化反应速率、耐温性、耐变性剂均有所提高,其中Ca2+金属磷酸盐合成的杂化脂肪酶催化效率是游离脂肪酶的1.87倍,合成的杂化脂肪酶表现出良好的重复使用性。     

Practical security analysis of continuous-variable quantum key distribution with an unbalanced heterodyne detector

When developing a practical continuous-variable quantum key distribution (CVQKD), the detector is necessary at the receiver's side. We investigate the practical security of the CVQKD system with an unbalanced heterodyne detector. The results show that unbalanced heterodyne detector introduces extra excess noise into the system and decreases the lower bound of the secret key rate without awareness of the legitimate communicators, which leaves loopholes for Eve to attack the system. In addition, we find that the secret key rate decreases more severely with the increase in the degree of imbalance and the excess noise induced by the imbalance is proportional to the intensity of the local oscillator (LO) under the same degree of imbalance. Finally, a countermeasure is proposed to resist these kinds of effects.     

Description of the candidate chiral doublet bands in 98Tc

The candidate chiral doublet bands in ⁹⁸Tc with configuration πg_9/2 × νh_11/2 are studied theoretically for the first time via the triaxial particle rotor model. The main properties of the doublet bands including the energy spectra and electromagnetic transitions are calculated for different triaxiality parameter γ, and the data in ⁹⁸Tc can be well described by the calculations with γ=38°. Based on the analysis of angular momentum components, it is found that the chiral rotational geometry in ⁹⁸Tc deviates from the ideal chiral picture.     

加压高通量CFB上升管气固流动特性实验研究

通过实验的方法考察了加压下,平均粒径为137μm、密度为2490 kg·m^-3的Geldart B类颗粒在固体通量为183～773 kg·m^-2·s^-1的高通量循环流化床上升管内的流动特性。结果表明,加压下七升管压降曲线近似线性分布。随着操作压力的增加,上升管底部颗粒浓度先增大后减小,顶部颗粒浓度逐渐增大,密相区的范围也逐渐增大。加压下截面平均颗粒浓度随颗粒循环速率和操作气速的变化和常压相类似,即随颗粒循环速率的增加而增加,随操作气速的增加而降低。     

Ⅱ型糖尿病人与大鼠红细胞拉曼光谱学比较

使用激光共聚焦拉曼光谱仪测量正常大鼠红细胞、正常人红细胞、糖尿病STZ造模大鼠红细胞、糖尿病四氧嘧啶造模大鼠红细胞和人Ⅱ型糖尿病红细胞的拉曼光谱,应用主成分分析(principal component analysis,PCA)结合支持向量机(support vector machines,SVM)分类器对数据进行判别分析,然后采用类间距离判断两种造模方法与人Ⅱ型糖尿病的接近程度。结果发现糖尿病红细胞与正常红细胞的拉曼光谱存在明显差异,糖尿病在酰胺 ⅥCO变形振动谱带处峰高显著,并在酰胺ⅤN—H变形振动谱带处谱线出现偏移,属于磷脂的脂酰基C—C骨架1 130 cm-1谱线增强,1 088 cm-1谱线强度减弱,说明糖尿病红细胞膜的通透性增强。PCA结合SVM可以很好地区分以上5类红细胞的拉曼光谱,分类器测试结果表明分类准确度达100%。通过分别计算两种造模方法与人Ⅱ型糖尿病的类间距离,发现STZ造模法更接近人Ⅱ型糖尿病。由此得出结论：拉曼光谱法可以用于糖尿病诊断,大鼠糖尿病STZ造模法更接近人类Ⅱ型糖尿病。     

基于多算法优化SVM的粗糙面参数反演

支持向量机（SVM）是粗糙面参数反演中常用的一种反演算法,SVM反演中的惩罚参数C和核函数参数G对反演结果精度的影响较大,若参数取值不当,会使模型产生"过学习"或者"欠学习"的现象,从而降低预测精度.给出几种SVM参数C和参数G的优化算法,如K折交叉验证（K-CV）、遗传算法（GA）和粒子群算法（PSO）,并在此基础上提出一种基于K-CV和GA改进的PSO算法（GA-CV-PSO）.利用矩量法（MoM）获得的粗糙面后向散射系数构造训练集和测试集,通过不同参数反演的仿真结果对比不同优化算法的反演精度和计算时间,表明GA-CV-PSO算法克服了单一优化算法的缺陷,具有更精确的反演精度和更强的泛化能力.     

Electrically and Optically Bistable Operation in an Integration of a 1310 nm DFB Laser and a Tunneling Diode

We experimentally demonstrate an In P-based hybrid integration of a single-mode DFB laser emitting at around 1310 nm and a tunneling diode. The evident negative differential resistance regions are obtained in both electrical and optical output characteristics. The electrical and optical bistabilities controlled by the voltage through the tunneling diode are also measured. When the voltage changes between 1.46 V and 1.66 V, a 200-mV-wide hysteresis loop and an optical power ON/OFF ratio of 17 dB are obtained. A side-mode suppression ratio of the integrated device in the ON state is up to 43 dB. The tunneling diode can switch on/off the laser within a very small voltage range compared with that directly controlled by a voltage source.