Determination of Malathion Using Corona Discharge – Ion Mobility Spectrometry with Solid-Phase Microextraction

A corona discharge (CD) ion mobility spectrometer combined with solid-phase microextraction was constructed. The detection limit and stability of the system for malathion detection were improved using a novel sample introduction port through which the sample desorption was performed in high-temperature drift tube and the sample was introduced directly to the ionization area. The working parameters of the distance between CD needle tip and carrier gas outlet, the drift tube and carrier gas temperature, the carrier gas flow, and the voltage on CD needle were selected. When the extraction time for standard malathion was set to 5?min, the detection limit was 0.96?µg?L^?1 based on thrice the baseline noise, the linear range was 50–500?µg?L^?1, the correlation coefficient was approximately 0.9941, and the relative standard deviation was below 10%. Malathion-spiked lake water samples were analyzed using the developed system and the recovery was 92–102%. This method is suitable for the rapid detection of organophosphorus pesticide residues.     

鲍曼不动杆菌LpxC的同源模建及分子对接

鲍曼不动杆菌已成为最普遍的医院致病菌,且耐药情况严峻.LpxC作为新抗菌药物靶点被大量研究,但鲍曼不动杆菌LpxC晶体尚未解析得到,基于其结构的药物设计等工作无法开展.以铜绿假单胞菌LpxC晶体结构为模板,通过同源模建方法获得鲍曼不动杆菌LpxC结构模型.较好的Ramachandran plot分布和Profile-3D结果验证了模型的合理性.用分子动力学模拟优化鲍曼不动杆菌LpxC模型,修补部分不合理构象.后续分子对接结果显示S构型的苄氧乙酰基羟肟酸类抑制剂比R构型分子能更有效地结合在F191,H237和K238组成的较浅口袋中,这可能是S构型抑制剂活性更高的主要因素,模拟结果与实验数据吻合较好.     

Distinct magnetic properties of one novel type of nanoscale cobalt-iron Prussian blue analogues synthesized in microemulsion

One novel type of nanoscale cobalt-iron Prussian blue analogues (PBA) in the form of mixed nanorods and nanocubes were synthesized using cetyltrimethyl ammonium bromide (CTAB) as the surfactant in microemulsion at low temperature. The generated products were characterized by SQUID, XRD and IR techniques, etc. The effects of potassium contents, cobalt-to-iron ratios, reaction temperatures on the properties of the nanoscale cobalt-iron PBA were systematically explored. The results showed that the novel type of nanomaterials possessed distinct magnetic properties in that their coercivities were intensely dependent on cobalt-to-iron ratios and potassium contents. Furthermore, it was observed that low reaction temperature not only affected the morphologies of the products, but also had influence on their magnetic properties. Additionally, the cobalt-iron Prussian blue analogues were strongly influenced by CTAB around their surface, which led to higher Curie temperatures.     

An experimental study about the effect of arrangement on the fire behaviors of lithium-ion batteries

The gadolinium ferrochromite (GdFe_1?xCr_xO₃) was used as a case study of influence of chromium substitution on the perovskite structure in the entire composition range. By exploiting thermal analysis techniques (dilatometry, differential thermal analysis) the influence of chromium was investigated in the context of thermal stability of the canted antiferromagnetic ordering. It was found that the higher the chromium concentration was, the more the Néel temperature decreased, e.g., substitution of 26 % of iron atoms corresponded to a depression of about 60 K with respect to undoped gadolinium ferrite. For higher chromium concentrations the mixed gadolinium ferrochromite was paramagnetic at room temperature. Additional information on the crystal structure and, qualitatively, on the magnetic ordering as well was derived from the results of X-ray diffraction and Mössbauer spectroscopy measurements. For chromium content higher than 10 % the gadolinium ferrochromite may be regarded as a solid solution. For lower concentrations, however, a possible formation of clusters with different Fe/Cr ratio occurs as suggested by Mössbauer spectra.     

几何光学教学中关于变折射率材料问题的计算实例

针对大学光学课程中所讨论的成像问题均为"近轴近似"这一情形,指出为增强教学效果、提升学生对所学理论在实践上的信心,需对非近轴近似的一般化情形给予一定讨论;明确了直接从费马原理反解折射率变化规律的不可行性,采用近似办法,将变折射率的泛函问题转化为关于斜率的一维函数问题,利用欧拉方程进行分析,通过数值计算得出适合于材料制作的一组参考参数.     

一种跨企业项目资源的描述方法

跨企业项目是跨企业组织最主要的生产运营方式,跨企业项目中的资源在项目运行过程中起到至关重要的作用,往往成为主宰跨企业项目成败的关键因素.文中给出一种跨企业项目资源的组织模型及其数学描述方法.     

航拍图像效果增强软件研究

图像效果增强软件在航拍图像的后期处理中具有重要的作用,为了实现航拍图像效果增强软件,首先对软件进行了总体设计;其次对软件中涉及的主要图像处理算法原理进行了分析（自适应中值滤波算法、边缘检测算法以及SPIHT编解码算法）;最后,采用VC＋＋6.0和Matlab实现了该软件,同时对软件中主要算法的航拍图像处理效果进行了实验...     

Experiment on relationship between the magnetic gradient of low-carbon steel and its stress

In geomagnetic field, a series of tensile experiments on the low-carbon steel sticks were carried out. A special homemade detector was used to measure the magnetic gradient on the material surface. The results showed that the relationship between the magnetic gradient and the stress varied with different conditions of measurement. There was no obvious correlation between the magnetic gradient and the tensile stress if the sample remained on the material test machine. If the sample was taken off from the machine, the measured magnetic gradient was linear with the prior maximum stress. In Nanjing, PR China, a place of 32°N latitude, the slope of the linear relationship was about 67 (uT/m)/MPa. This offered a new method of non-destructive stress testing by measuring the magnetic gradient on the ferromagnetic component surface. The prior maximum applied stress of the sample could be tested by measuring the present surface magnetic gradient. Actually this phenomenon was the metal magnetic memory (MMM). The magnetic gradient near the stress concentration zone of the sample, the necking point, was much larger than other area. Thus, the hidden damage in the ferromagnetic component could be detected early by measuring the magnetic gradient distribution on its surface. In addition, the magnetic memory signal gradually weakened as the sample was taken off and laid aside. Therefore, it was effective for a given period of time to detect the stress or stress concentration based on the MMM testing.     

早期干预对极低出生体重早产儿智能发育的影响研究

目的 探讨早期干预对极低出生体重早产儿智能发育的影响,为极低出生体重早产儿的早期干预提供依据。方法 239 例极低出生体重早产儿为早产随访组,采用鲍秀兰早期教育资料制定的干预计划,进行系统干预,并与326 例失访的早产儿童以及与随访组相似的326 例正常儿童进行对照分析。采用Gesell 儿童发育量表等标准化工具进行发育评估。结果 早产随访组Gesell 儿童发育量表5 项均分、总发育商（developmental quotient,DQ）总分与早产失访组相比差异均有统计学差异（均P＜0.05）。结论 早期干预能显著促进极低出生体重早产儿的智能发育,提高患儿的生活质量。