MCNOs/CdS双效光催化剂的制备及其性能研究

水热合成法制备了不同磁性纳米洋葱碳(MCNOs)负载量(0%、1%、3%、5%)的MCNOs/CdS光催化剂。并通过X射线衍射分析(XRD)、扫描电子显微镜(SEM)、傅里叶红外光谱(FT-IR)、X射线光电子能谱(XPS)、紫外可见光光谱(UV-Vis)、磁滞回线测定仪(VSM)对其进行表征,探究了MCNOs负载比例对催化剂在可见光下降解RhB性能及机理的影响。结果表明,MCNOs能有效提高CdS的光催化效果,复合3%MCNOs后降解率为96%,与纯CdS相比降解率提高了30%,磁性分析表明,其具有良好的顺磁性并能实现催化剂的有效回收。MCNOs/CdS在可见光下催化降解RhB的一级反应动力学直线有较好的拟合度,表明制备的催化剂有较好的催化活性。     

Scaling Behavior between Heat Capacity and Thermal Expansion in Solids

We experimentally analyze the heat capacity and thermal expansion of reference solids in a wide temperature range from several Kelvin to melting temperature,and establish a universal double-linear relation between the experimental heat capacity C_p and thermal expansion β,which is different from the previous models.The universal behavior between heat capacity and thermal expansion is important to predict the thermodynamic parameters at constant pressure,and is helpful for understanding the nature of thermal properties in solids.     

利用沉积物和水体的环境DNA检测鱼类物种多样性的差异

环境DNA(environmental DNA,eDNA)调查因其敏感且能提供高分辨率的群落组成数据,正越来越多地被用于生物多样性的监测。但环境DNA研究评估不同的环境样本类型如何影响物种的可检测性仍然很少。在此,我们利用线粒体细胞色素b基因的环境DNA宏条形码比较了鄱阳湖中沉积物和水体的鱼类群落组成。结果显示:沉积物样本注释到6目10科18种,水体样本中注释到5目7科13种。沉积物和水体环境DNA共同注释到8种鱼类(32%)。本研究注释到的鱼以鲤科鱼类居多,且以小型、湖泊定居型、杂食性鱼类为主。沉积物样本中检测到的鱼类的多样性高于水体中的。鱼类环境DNA有垂直分布差异。本研究得出结论,在进行环境DNA调查时需要仔细考虑环境样本类型。建议在使用环境DNA进行鱼类资源研究时,取样策略采取沉积物样本和水体样本相结合将会更有意义。     

AuNP aggregation-induced quantitative colorimetric aptasensing of sulfadimethoxine with a smartphone

A gold nanoparticle(AuNP) aggregation-induced colorimetric aptasensing method for quantitative detection of sulfadimethoxine(SDM) with a smartphone was developed. AuNPs were complexed with aptamers which protected Au NPs from aggregating in high-concentration salt solutions. In the presence of SDM,SDM bound with the aptamer on the surface of Au NPs with higher affinity, which competitively desorbed the aptamer from the AuNP surface and resulted in AuNPs aggregation, accompanied with a color chan...     

Controllable annulus micro-/nanostructures on copper fabricated by femtosecond laser with spatial doughnut distribution

In this study,we propose an effective method for the fabrication of annulus micro-/nanostructures by a femtosecond laser doughnut beam.Compared with the traditional Bessel annulus beam shaping system,this method greatly compresses the light propagation path.It is theoretically and experimentally demonstrated that the obtained axial section of the peak envelope in the processing area is two waists of the isosceles triangle.By moving the relative position of the sample,annulus microstructures with different diameters on copper sheet could be fabricated.In addition,laser induced periodic surface structures with controllable direction are fabricated by this optical system.     

Identification of Residue Involved in Nucleotidyltransferase Activity of LinA from Staphylococci by Site-directed Mutagenesis

The lincosamide class of antibacterials is widely used for the treatment of a broad spectrum of infections, and one prevalent route of resistance to lincosamides in pathogenic gram-positive cocco is antibiotic modification. Enzymes encoded by lin genes, belonging to nucleotidyltransferase superfamily, catalyze adenylylation to inactivate lincosamides. LinA can adenylylate lincosamides at either 3?-or 4?-OH of the methylthiolincosamide sugar. The crystal structure of LinA/lincomycin has confirmed its active site. However, the residue interacting with nucleotidyl donors remains elusive. Here, we modeled the complex structure of LinA/lincomycin/Mg~(2+)/AMPCPP to reveal a putative pocket for nucleotidyl donors and suggested the residue R45 in this pocket involved in the recognition of donor substrates NTP and catalysis. ITC and enzyme activity assays show that the mutation of residue R45 impairs LinA nucleotidyltransferase activity in vitro. This work provides insights into the molecular mechanism of the nucleotide binding and transferring activity of antibiotic NTases.     

闭开联合楔横轧微观组织温度的影响规律

以42CrMo钢为研究材料,在Deform-3D软件中建立了闭开联合楔横轧热-力-微观组织耦合的有限元模型.通过单因素方法,分析了轧制温度对轧件平均晶粒尺寸的影响规律.结果表明,降低轧制温度,轧件越有利于结晶,平均晶粒尺寸越小;闭式轧制后晶粒随着温度的降低整体得到细化;开式阶段晶粒随着温度的升高,平均晶粒大小变化不明显.通过金相实验与模拟对比发现,两者曲线趋势一致,误差为15%,验证了有限元模拟的可靠性.     

Design of diamond-shape photonic crystal fiber polarization filter based on surface plasma resonance effect

A novel plasmonic polarization filter based on the diamond-shape photonic crystal fiber(PCF) is proposed. The resonant coupling characteristics of the PCF polarization filter are investigated by the full-vector finite-element method. By optimizing the geometric parameters of the PCF, when the fiber length is 5 mm, the polarization filter has a bandwidth of 990 nm and an extinction ratio(ER) of lower than -20 dB. Moreover, a single wavelength polarization filter can also be achieved, along with an ER of -279.78 dB at wavelength 1.55 μm. It is believed that the proposed PCF polarization filter will be very useful in laser and optical communication systems.     

Na原子链表面等离激元特性的含时密度泛函研究

本文用含时密度泛函理论研究了线性Na原子链的表面等离激元机理.主要在原子尺度下模拟计算了体系随着原子数增加及原子间距变化的集体激发过程.研究发现线性原子链有一个普遍的特性——存在一个纵模和两个横模.两个横模一般在实验上很难被观测到.纵模随着原子链长度增加,能量红移的同时,该纵模主峰的强度呈线性增长.随着原子个数的增加,端点模式(TE)开始蓝移,能量和偶极强度都逐渐趋向饱和.横模能量被劈裂的原因概括如下:(一)每个位置的电子受到的势不同,在两端的电子受到的势要比在中间的电子受到的势要高,因此两端的电荷积累也比中间多;(二)端点存在悬挂键,所以中间的电子-电子间相互作用与端点的不一样,这两方面又都与原子间距d有关.