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781.
Solid‐phase extraction of explosive nitramines on macroreticular polymers modified by freezing with water or acetone 下载免费PDF全文
Waldemar Tomaszewski Vladimir M. Gun'ko Jadwiga Skubiszewska‐Zięba 《Journal of separation science》2016,39(8):1524-1532
A novel approach is proposed to modify the porous structure and surface properties of the polymers used in solid‐phase extraction. The approach involves soaking in water or acetone, followed by freezing in liquid nitrogen (77.4 K) and was employed for two polymeric materials: Amberlite XAD‐7 and Amberlite XAD‐16. Variations in the surface properties of the adsorbents were justified by the action of acetone and water as solvents affecting the textural and other characteristic of the materials. The initial and treated adsorbents were used in extraction of explosive nitramines from aqueous samples. The performed modifications of the polymer texture allow us to increase the recovery rate as compared with the initial adsorbents. The results were justified by the swelling of fragments of the polymers and by the additional process of sorption of nitramines. The results indicate that polymeric adsorbents can be easily modified by the soaking/freezing process and the materials can be achieved that prove usefulness for the effective separation of explosive nitramines from aqueous samples. 相似文献
782.
以DNA为模板,合成了具有荧光性质的银纳米簇(DNA-Ag NCs),利用荧光光谱、紫外光谱和红外光谱等手段对其进行了表征.基于DNA-Ag NCs与离子相互作用时产生的荧光变化可实现对离子浓度的检测.实验结果表明,在最佳实验条件下,Ni2+及Hg2+的浓度与DNA-Ag NCs荧光强度呈线性关系;并验证了该荧光探针用于检测自来水样品中汞离子和镍离子的实用性.由于以DNA为模板的DNA-Ag NCs能够响应多种刺激,如Ni2+,S2-,Hg2+和p H等,利用相应的荧光强度可构建多输入的DNA-Ag NCs逻辑门及其组合逻辑门.当荧光输出强度(Ioutput)>初始荧光强度(Iorigin)时,设定输出为1,采用各种刺激及其组合作为输入,构建了YES,INH和组合的NOR与INH逻辑门.而只有当Ioutput≥Iorigin时定义为输出为1,可建立NOT,NOR,组合的IMP加上NOR... 相似文献
783.
A simple, specific and sensitive LC-MS/MS assay for simultaneous determination of simvastatin (SV) and its active beta-hydroxy acid metabolite, simvastatin acid (SVA) in human plasma was developed using a statin analog as internal standard (IS). The method was validated over a dynamic linear range of 0.20-100.00 ng/mL for SV and 0.10-50.00 ng/mL for SVA with correlation coefficient r > or = 0.9987 and 0.9989, respectively. The analytes and IS were extracted from 500 microL aliquots of human plasma via liquid-liquid extraction using methyl tert-butyl ether and separated through an Aquasil C18 column (100 mm x 2.1 mm, 5 microm). Detection of analytes and IS was done by MS/MS with a turbo ion spray interface operating in positive ion and selective reaction monitoring acquisition mode. The total chromatographic run time was 3.0 min. Flash freezing of the aqueous phase was an added advantage during liquid-liquid extraction, which considerably reduced time and labour. The method was extensively validated for its accuracy, precision, recovery, stability studies and matrix effect. The method was successfully used for bioequivalence study of 40 mg SV tablet formulation in 12 human subjects under fasting condition. 相似文献
784.
使用焦散线法与光弹法测定三维裂纹混合型应力强度因子 总被引:1,自引:0,他引:1
本文介绍了将焦散线法与应力冻结,“解冻”技术相结合,使焦散线法用于测量三维体内部裂纹前缘应力强度因子的实验方法,并针对复杂应力状态下三维裂纹前缘的不同应变奇异场,合理地综合运用焦散线法与三维光弹法,实际测量与分离了三维裂纹前缘混合型应力强度因子。 相似文献
785.
786.
介绍了利用Mathematica软件包让普通微机通过声卡输出调试信号的方法,并直接用示波器观测了门电路的传输特性曲线。 相似文献
787.
A new design approach for a three-step modified signed-digit (MSD) adder is presented that can be optically implemented using binary logic gates. The proposed scheme depends on encoding each MSD digits into a pair of binary digits using a two-state and multi-position encoding scheme. The proposed design algorithm depends on constructing the addition truth table of binary-coded MSD numbers and then using Karnaugh map to achieve output minimization. The optical binary logic gates are obtained by simply programming the decoding masks of a shadow-casting-based optical logic gate system. The proposed scheme results in a simple, compact, and efficient optical binary gate-based parallel addition system. 相似文献
788.
This article deals with a computationally efficient serial distributed arithmetic algorithm producing a device efficient field programmable gate array implementation. The proposed algorithm takes half the computations time as compared to the conventional symmetric algorithms. The algorithm is analyzed for a direct conversion transmitter of ionospheric radar. Matching and buffering criterion are used to reduce the arithmetic process. The algorithm can be extended to applications with similar characteristics, particularly for System On Chip (SOC) techniques. © 2005 Wiley Periodicals, Inc. Complexity 11: 24–29, 2005 相似文献
789.
This article reviews the current status of high-κ dielectric materials for microelectronics. In particular, recent work impacting the integration of these high-κ materials for gate dielectric and capacitor applications in advanced scaled microelectronic devices is reviewed. 相似文献
790.
Yu. A. Sigunov Yu. A. Samylova 《Journal of Applied Mechanics and Technical Physics》2006,47(6):842-848
A model for the freezing of a closed volume of water with dissolved gases is proposed and studied numerically. It is shown
that gas release during ice formation leads to a considerable time delay in the time of a sudden pressure increase. In the
freezing process, the pressure depends not only on the volume of ice formed but also on the freezing rate, which is determined
by the cooling rate and the geometry and dimensions of the freezing volume.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 6, pp. 85–92, November–December, 2006. 相似文献