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991.
Elena Blanco Carlos Rodriguez-Abreu Pablo Schulz Juan M. Ruso 《Journal of colloid and interface science》2010,341(2):261-266
In this work we studied and compared the physicochemical properties of the catanionic mixtures cetyltrimethyl-ammonium bromide–sodium dodecanoate, cetyltrimethyl-ammonium bromide–sodium perfluorodacanoate, octyltrimethylammonium bromide–sodium perfluorodacanoate and cetyltrimethyl-ammonium bromide–sodium octanoate by a combination of rheological, transmission electron microscopy (TEM) and polarized optical microscopy measurements. The binary mixtures of the surfactants have been analyzed at different mixed ratios and total concentration of the mixture. Mixtures containing a perfluorinated surfactant are able to form lamellar liquid crystals and stable spontaneous vesicles. Meanwhile, system containing just hydrogenated surfactants form hexagonal phases or they are arranged in elongated aggregates. 相似文献
992.
993.
Derliane Oliveira Sook Fan Yap Siripan Wongwanich Baldip Khan Juan Cristina 《Accreditation and quality assurance》2010,15(2):89-97
Nucleic acid-based technologies have opened new perspectives in diagnosis, prognosis, and treatment in clinical medicine.
To maintain patient confidence in this rapidly expanding field and to provide the highest standard of analysis, strict laboratory
quality assurance procedures must be followed. While impressive break-through are taking place in this field, the need for
an appropriate and suitable quality assurance (QA) plan for nucleic acid-based diagnostic laboratories must be a top priority.
In this study, we developed a systematic QA plan for this kind of diagnostic laboratories that would enable us to assure the
highest quality standards of their services. We focus on those labs that would like to start introducing a quality system
for the first time and discuss the most appropriate ways to pave the way to implement a QA plan from the beginning. This QA
plan is suitable for any nucleic acid-based techniques laboratory regardless of the field or services provided. 相似文献
994.
In the present study, an ultra-performance liquid chromatography method with diode array detection (UPLC-DAD) was developed for the analysis and determination of leonurine from motherwort (Leonurus japonicus), a traditional Chinese medicinal plant. This method was validated in terms of specificity, linearity (R(2) = 0.9995, linear range: 0.005 ~ 0.5 mg/mL), precision (< 5.0% RSD), and recovery (103.2%). The extracted amount of leonurine is 0.15 mg/g. Moreover, the target analyte was identified or tentatively characterized using UPLC coupled with electrospary tandem mass spectrometry (UPLC-ESI-MS). 相似文献
995.
Campillo N Viñas P Cacho JI Peñalver R Hernández-Córdoba M 《Journal of chromatography. A》2010,1217(47):7323-7330
Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was evaluated for the simultaneous determination of five chlorophenols and seven haloanisoles in wines and cork stoppers. Parameters, such as the nature and volume of the extracting and disperser solvents, extraction time, salt addition, centrifugation time and sample volume or mass, affecting the DLLME were carefully optimized to extract and preconcentrate chlorophenols, in the form of their acetylated derivatives, and haloanisoles. In this extraction method, 1mL of acetone (disperser solvent) containing 30μL of carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5mL of sample solution containing 200μL of acetic anhydride (derivatizing reagent) and 0.5mL of phosphate buffer solution, thereby forming a cloudy solution. After extraction, phase separation was performed by centrifugation, and a volume of 4μL of the sedimented phase was analyzed by GC-MS. The wine samples were directly used for the DLLME extraction (red wines required a 1:1 dilution with water). For cork samples, the target analytes were first extracted with pentane, the solvent was evaporated and the residue reconstituted with acetone before DLLME. The use of an internal standard (2,4-dibromoanisole) notably improved the repeatability of the procedure. Under the optimized conditions, detection limits ranged from 0.004 to 0.108ngmL(-1) in wine samples (24-220pgg(-1) in corks), depending on the compound and the sample analyzed. The enrichment factors for haloanisoles were in the 380-700-fold range. 相似文献
996.
采用电化学沉淀法,成功地制备了多孔、高效聚苯胺固相微萃取涂层,并建立了顶空固相微萃取-气相色谱(HS-SPME-GC)快速测定水体和牛奶中的痕量多溴联苯醚的方法。详细研究了萃取模式、萃取温度、萃取时间、顶空体积及离子强度对萃取效率的影响。在优化实验条件下,本法测定的6种多溴联苯醚的线性范围为1~4000 ng/L(除BDE-154和BDE-153分别为1~3000 ng/L、1~2500 ng/L外),相关系数大于0.99,检出限(S/N=3)在0.08~0.20 ng/L之间,相对偏差小于8.5%(n=7)。自制聚苯胺涂层对多溴联苯醚的萃取效率优于商品化100μm-PDMS纤维。将本法用于河水和牛奶中痕量多溴联苯醚的测定,实际样品回收率分别在90%和80%以上。 相似文献
997.
在AZ91D镁合金中添加稀土元素Ce和Y,研究了Ce,Y元素在铸态AZ91D镁合金中的存在形式以及对合金组织和性能的影响。结果表明,铸态AZ91D镁合金中加入的Ce,Y大部分形成Al4Ce和Al2Y化合物,少量剩余的Ce,Y部分取代Mg元素的位置,以代位固溶的形式固溶在α-Mg固溶体和β-Mg17Al12金属间化合物中;Ce,Y能够细化镁合金铸态组织的晶粒,使Mg17Al12相发生"断网"并减少其在组织中的相对比例;适量添加Ce,Y能够提高AZ91D镁合金铸态机械性能,其主要原因是Ce,Y的细晶作用、固溶强化作用、Al-RE相的第二相强化作用以及对Mg17Al12相强化作用的改善。 相似文献
998.
999.
1000.
Introduction to focus issue: mesoscales in complex networks 总被引:1,自引:0,他引:1