氢气对AlN薄膜择优取向的作用机制

采用脉冲反应磁控溅射方法在Si衬底上沉积了(100)和(002)择优取向的AlN薄膜,随着溅射功率的降低或氢气浓度的增加,放电电压下降,沉积粒子能量降低,薄膜由(002)取向逐渐向(100)取向转变.在溅射气氛中加入氢气后,薄膜中的氧含量降低,表面形貌与表面粗糙度均随着择优取向的改变发生变化.溅射功率及氢气浓度对AlN薄膜择优取向的影响规律表明,氢气主要是通过降低沉积粒子的能量和在衬底表面产生吸附两种作用方式来影响AlN薄膜的择优取向.     

超高效液相色谱-线性离子阱/静电场轨道阱高分辨质谱鉴别纺织品中禁用芳香胺及其异构体

针对目前纺织品中禁用偶氮染料检测中的假阳性问题,建立了一套应用超高效液相色谱-线性离子阱/静电场轨道阱高分辨质谱（UPLC-LTQ/Orbitrap）同时筛选24种禁用芳香胺及其常见的14种异构体的方法。样品经连二亚硫酸钠还原,叔丁基甲醚提取后,以水/甲醇（9/1,v/v）稀释定容,用ZORBAX SB-C₁₈色谱柱（150 mm×2.1 mm,5 μm）分离,以0.1%甲酸水溶液和甲醇为流动相,电喷雾正离子（ESI⁺）模式电离。以准分子离子峰的精确质量数和保留时间定性,以提取的色谱图峰面积定量。38种芳香胺的线性相关系数大于0.99,方法检出限为0.5~5 μg/kg。该方法可通过一次实验同时对24种禁用芳香胺及其常见的14种异构体准确定性定量,大大缩短检测周期,实际样品检测也进一步验证了其灵敏性和准确性。     

Ratiometric Fluorescent Probe Based on Novel Red-emission BODIPY for Determination of Bovine Serum Albumin

A novel red-emission boron-dipyrromethene（BODIPY） dye with a pyrrole ring was synthesized simply via one-pot reaction. The spectral properties of it were investigated under the conditions of different solvents. The results show that the as-prepared BODIPY dye is extremely sensitive to solvent polarity, and the fluorescent emission enhances with the decrease of solvent polarity. In aqueous buffer, the addition of bovine serum albumin leads to a ratiometric change in absorption spectra with an association constant of 1.16×10^6 L/mol. Meanwhile, the fluorescence emission increases greatly at 622 nm but changes slightly at 575 nm. The response time is very short（less than 3 min）, and the changes of color can be noticed by naked eyes. Bovine serum albumin can be detected by this ratiometric fluorescence probe, but other proteins or enzymes cannot be detected by this method, which indicates that this novel dye has high selectivity towards bovine serum albumin. The reason is that bovine serum albumin has suitable hydro- phobic cavities for binding with the dye. In addition, the dye molecule can penetrate cell membrane easily and make a fast fluorescent stain, which makes it a potential probe for living-cell fluorescence imaging.     

Synthesis and Antitumor Activity of 4-tert-Butyl-5-benzyl-2-benzyliminothiazoles

A series of novel Schiff bases including 4-tert-butyl-5-benzyl-2-benzyliminothiazoles was synthesized by reacting the aromatic aldehydes with the corresponding 2-aminothiazoles.The antitumor bioassay revealed that compounds 2n and 2m exhibited potent cytotoxicity against human cervix cancer（HeLa） cell line with IC50 values of 0.001 and 0.007 mmol/L,respectively.The preliminary structure-activity relationship（SAR） investigations and the apoptosis evaluation suggest that 4-tert-butyl-5-benzyl-2-benzyliminothiazoles may be a satisfactory backbone for antitumor activity,and compound 2n can serve as an attractive candidate for the development of novel apoptosis in anticancer treatment.     

Synthesis,Structure and Characterization of Three Metal Molybdate Hydrates: Fe(H2O)2(MoO4)2·H3O,NaCo2(MoO4)2(H3O2)and Mn2(MoO4)3·2H3O

Three metal molybdate hydrates,Fe(H2O)2(MoO4)2·H3O(FeMo),NaCo2(MoO4)2(H3O2)(CoMo)and Mn2(MoO4)3·2H3O(MnMo),were synthesized by the mixed-solvent-thermal methods and characterized by singlecrystal X-ray...     

Influence of Steric Hindrance Between Hydrogen Atoms of Linkage Groups and Adjacent Phenyls on Properties of Polyimide

A diamine monomer 4,4′-methylenedianiline(MDA) was introduced to modify the polyimide of pyromellitic dianhydride(PMDA) and 4,4′-oxydianiline(ODA) by polycondensation. A series of polyamic acids was synthesized from MDA and ODA of different molar ratios with PMDA of sum mole of moles of MDA and ODA, and polyimide films were obtained by thermal imidization. Polyimide(PI) films were characterized by tensile testing, dynamic mechanical analysis(DMA), thermal gravimetry analysis(TGA), Fourier transform infrared spectroscopy (FTIR), wide X-ray diffraction(WAXD) and molecular simulation. With the increase of MDA content, the tensile strength and thermal decomposition temperature remained generally stable compared with those of PMDA/ODA polyimide. Unexpectedly, the glass transition temperature(T_g) and Young’s modulus increased from 388.7 ℃ and 2.37 GPa to 408.3 ℃ and 5.74 GPa, respectively. The results of WAXD and molecular simulation indicate the steric hindrance among hydrogen atoms of the linkage groups and adjacent phenyls enhanced the properties of the polyimide modified with MDA.     

老鼠血清中苯扎贝特的HPLC-MS法测定

建立一种简便、快速、灵敏的高效液相色谱-质谱联用测定老鼠血清中苯扎贝特的方法。 采用Gemini C18色谱柱;流动相：V(乙腈)∶V(甲醇)∶V(水)=60∶15∶25(0.03%甲酸水溶液);柱温35 ℃,流速0.3 mL/min;紫外吸收波长为235 nm;进样量5 μL。 质谱采用电喷雾电离负离子模式,用于定量分析的离子分别为[M-H]- m/z 359.65→273.70(苯扎贝特)和[M-H]- m/z 212.95→127.08(氯贝酸)。 对苯扎贝特检测的线性范围为0.073~7.884 mg/L,r=0.9995。 得到苯扎贝特的平均回收率为94.3%~103.1%;方法的日内和日间的相对标准偏差(RSD)均小于6%;最低检测限(LOD)与定量限(LOQ)分别为9.0和30 μg/L;为临床上人体血清中苯扎贝特的浓度检测提供了一种重现性好、灵敏度高的分析方法。     

Digital discrimination of neutrons and γ rays with organic scintillation detectors in an 8-bit sampling system using frequency gradient analysis

The feasibility of using frequency gradient analysis (FGA), a digital method based on Fourier transform, to discriminate neutrons and γ rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and γ rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison (CC) methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.     

复合材料层板的抗贯穿机理与模拟研究

为了研究树脂基纤维增强复合材料层板的抗侵彻贯穿机理和动态力学行为与抗侵彻毁伤的关系, 通过球形破片模拟弹贯穿实验表征了复合材料层板抗高速侵彻的吸能特性;通过高速摄影技术分析了层板 贯穿过程的瞬态变形失效特点;采用CT扫描成像及SEM 电镜分析等手段研究了复合材料层板的抗贯穿破 坏耗能模式。实验结果显示,高速冲击下层板抗贯穿吸能与入射速度成正比;高速侵彻过程是复合材料层板 高应变率变形的动态过程,高应变率动态力学行为对复合层板抗贯穿吸能特性影响显著;冲击波在层板中的 传播特性决定了不同破坏模式阶段的划分以及损伤区域的范围。基于复合层板高速贯穿下的动力学瞬态分 析,建立了复合层板抗高速侵彻吸能的两阶段动态破坏模型,模型计算值与实验值符合良好。研究结果表明, 应变率效应与惯性效应在复合材料层板抗侵彻性能分析中是不可忽视的2个关键因素。     

多渐消因子卡尔曼滤波及其在SINS初始对准中的应用

针对卡尔曼滤波在系统模型失配和未知干扰情况下鲁棒性差的特点,对于一类线性模型提出了多渐消因子卡尔曼滤波算法。该算法利用卡尔曼滤波取得最佳增益时残差序列互不相关的性质,可以在线自适应地调整多个渐消因子,从而对多个数据通道进行渐消,即使当滤波达到稳态时仍然可以调整滤波增益,使得该算法对模型失配和未知干扰有较强的鲁棒性。将该算法用于噪声统计不准确的SINS初始对准,数值仿真表明,当系统模型存在不准确情况时,新方法对航向误差角的估计精度较单渐消因子卡尔曼滤波和常规卡尔曼滤波分别提高了70%和43%,证明了该算法的有效性。