排序方式: 共有22条查询结果,搜索用时 31 毫秒
1.
JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatography (HPTLC) method was developed... 相似文献
2.
Pinched flow coupled shear-modulated inertial microfluidics for high-throughput rare blood cell separation 总被引:1,自引:0,他引:1
Blood is a highly complex bio-fluid with cellular components making up >40% of the total volume, thus making its analysis challenging and time-consuming. In this work, we introduce a high-throughput size-based separation method for processing diluted blood using inertial microfluidics. The technique takes advantage of the preferential cell focusing in high aspect-ratio microchannels coupled with pinched flow dynamics for isolating low abundance cells from blood. As an application of the developed technique, we demonstrate the isolation of cancer cells (circulating tumor cells (CTCs)) spiked in blood by exploiting the difference in size between CTCs and hematologic cells. The microchannel dimensions and processing parameters were optimized to enable high throughput and high resolution separation, comparable to existing CTC isolation technologies. Results from experiments conducted with MCF-7 cells spiked into whole blood indicate >80% cell recovery with an impressive 3.25 × 10(5) fold enrichment over red blood cells (RBCs) and 1.2 × 10(4) fold enrichment over peripheral blood leukocytes (PBL). In spite of a 20× sample dilution, the fast operating flow rate allows the processing of ~10(8) cells min(-1) through a single microfluidic device. The device design can be easily customized for isolating other rare cells from blood including peripheral blood leukocytes and fetal nucleated red blood cells by simply varying the 'pinching' width. The advantage of simple label-free separation, combined with the ability to retrieve viable cells post enrichment and minimal sample pre-processing presents numerous applications for use in clinical diagnosis and conducting fundamental studies. 相似文献
3.
Study of the Degradation Kinetics of Carvedilol by Use of a Validated Stability-Indicating LC Method
Mohammad Rizwan Mohammed Aqil Adnan Azeem Yasmin Sultana Sushama Talegaonkar Asgar Ali 《Chromatographia》2009,70(7-8):1283-1286
The objectives of this investigation were to establish a validated stability-indicating LC method for assay of carvedilol and to study the degradation behaviour of the drug under different ICH-recommended stress conditions. Chromatographic separation was achieved on a C18 column with 55:45 (%, v/v) acetonitrile–0.02 m phosphate buffer, pH 3.5, as mobile phase at a flow rate of 1.0 mL min?1; detection was by UV absorbance at 242 nm. The method was validated for linearity, precision, accuracy, robustness, specificity, and sensitivity, with the bulk drug. The drug was subjected to forced degradation and peaks of all the degradation products were well resolved from that of the pure drug, with significantly different retention times, which indicates the specificity and stability-indicating properties of the method. First-order degradation kinetics of carvedilol were observed under acidic and alkaline conditions. When the utility of the method was verified by analysis of the drug in marketed tablets and a nano-emulsion formulation, the assay was found to be 98.60–99.61 and 99.52–99.87, respectively. These results indicate the method can be successfully used for routine analysis of carvedilol in the bulk drug and in pharmaceutical dosage forms. 相似文献
4.
Asgar Jamneshan Michael Kupper Martin Streckfuß 《Set-Valued and Variational Analysis》2018,26(4):947-973
The aim of this article is to establish basic results in a conditional measure theory. The results are applied to prove that arbitrary kernels and conditional distributions are represented by measures in a conditional set theory. In particular, this extends the usual representation results for separable spaces. 相似文献
5.
We demonstrate rapid mixing of sub-microlitre droplets (250 nl) using miniaturized magnetic stir bars (400 μm × 200 μm × 15 μm). The stir bars are fabricated using laser micromachining and placed on the substrate on which the drops are manipulated. They are activated by an externally applied magnetic field and used in combination with on-demand drop merging in enthalpy arrays. This technique results in a 10-fold increase in mixing rate, and a mixing time constant of about 2 s. Drop mixing times are measured by F?rster resonance energy transfer (FRET) and verified by thermodynamic measurements of binding and enzymatic reactions. 相似文献
6.
Asgar Ebadollahi Jalal Jalali Sendi William N. Setzer Tanasak Changbunjong 《Molecules (Basel, Switzerland)》2022,27(11)
Although the use of synthetic chemicals is the principal method for insect pest management, their widespread application has led to numerous side effects, including environmental pollution and threats to human and animal health. Plant essential oils have been introduced as promising natural substitutes for synthetic insecticides. However, high volatility and/or low durability are the main limiting factors for essential oil application for control of insect pests. Accordingly, along with an evaluation of the fumigant toxicity of Eucalyptus largiflorens essential oil against the cowpea weevil, Callosobruchus maculatus, essential oil was nanoencapsulated by two mesoporous silicates, MCM-41 and zeolite 3A, to enhance fumigant persistence and toxicity. The chemical profile of essential oil was also analyzed through gas chromatographic-mass spectrometry. E. largiflorens essential oil showed significant concentration-dependent toxicity against insect pests; a concentration of 5.16 μL/L resulted in 100% mortality after 48 h. The toxicity of essential oil could be attributed to the presence of various insecticidal terpenes, such as spathulenol (15.6%), cryptone (7.0%), and 1,8-cineole (5.8%). Fumigant persistence was increased from 6 days to 19 and 17 days for pure and capsulated essential oil with MCM-41 and Zeolite 3A, respectively. The insect mortality also increased from 99 insects in pure essential oil to 178 and 180 insects in MCM-41 and Zeolite 3A encapsulated formulations, respectively. Therefore, the encapsulation of E. largiflorens essential oil by MCM- 41 and Zeolite 3A is a beneficial method for enhancing its persistence and toxicity against C. maculatus. 相似文献
7.
Continuous particle separation in spiral microchannels using Dean flows and differential migration 总被引:1,自引:0,他引:1
Microparticle separation and concentration based on size has become indispensable in many biomedical and environmental applications. In this paper we describe a passive microfluidic device with spiral microchannel geometry for complete separation of particles. The design takes advantage of the inertial lift and viscous drag forces acting on particles of various sizes to achieve differential migration, and hence separation, of microparticles. The dominant inertial forces and the Dean rotation force due to the spiral microchannel geometry cause the larger particles to occupy a single equilibrium position near the inner microchannel wall. The smaller particles migrate to the outer half of the channel under the influence of Dean forces resulting in the formation of two distinct particle streams which are collected in two separate outputs. This is the first demonstration that takes advantage of the dual role of Dean forces for focusing larger particles in a single equilibrium position and transposing the smaller particles from the inner half to the outer half of the microchannel cross-section. The 5-loop spiral microchannel 100 microm wide and 50 microm high was used to successfully demonstrate a complete separation of 7.32 microm and 1.9 microm particles at Dean number De = 0.47. Analytical analysis supporting the experiments and models is also presented. The simple planar structure of the separator offers simple fabrication and makes it ideal for integration with on-chip microfluidic systems, such as micro total analysis systems (muTAS) or lab-on-a-chip (LOC) for continuous filtration and separation applications. 相似文献
8.
Abdul Karim Shah Sungsoo Park Hassnain Abbas Khan Umair Hassan Bhatti Praveen Kumar Abdul Waheed Bhutto Yeung Ho Park 《Research on Chemical Intermediates》2018,44(4):2405-2423
Citronellal cyclisation to isopulegol is an important intermediate step in the production of menthol. Several heteropoly acids (PTA) supported on modified montmorillonite (MM) catalysts were synthesized and then tested in cyclisation reactions. The prepared samples were characterized by XRD, ICP-OES, FTIR, N2 sorption, NH3-TPD, pyridine adsorption, amine titration and FE-SEM techniques. Effects of post-treatment were studied on montmorillonite pore structure, acidity and catalytic activity. The catalytic activity and isopulegol selectivity improved with acid-treatment and PTA loading. The amount of Lewis acidity of montmorillonite was enhanced with acid-treatment and PTA impregnation. In cyclisation, highest catalytic activity (31.87 mmol cat g?1 min?1) was achieved with 96% isopulegol yield in the use of 20% PTA-MM catalyst. The highest catalytic activity and selectivity were obtained in the presence of higher acidity and strong Lewis acidic sites, whereas effects of pore structure blockage seemed minor. The catalytic activity further decreased with the loss of active acidic sites (L and B) due to PTA decomposition with calcination at a higher temperature. 相似文献
9.
Olcay Mert Asgar Kayan 《Journal of inclusion phenomena and macrocyclic chemistry》2014,80(3-4):409-416
In this study, zirconium salicylate compounds (1–6) were prepared by reaction of zirconium(IV) propoxide with 5-chlorosalicylic acid, 4-hydroxysalicylic acid, and 5-nitrosalicylic acid in 1-propanol, respectively. All these compounds (1–6) were characterized by 1H, 13C NMR, FTIR, mass spectroscopy, elemental, and thermogravimetric analyses. These compounds were tested as catalysts in polymerization of ε-caprolactone and were effective. Polycaprolactone was characterized by 1H, 13C NMR, and gel permeation chromatography. The number of salicylate ligands (bonded to zirconium atom) effects and substituents (on salicylate ligands) effects on the polymerization reactions were investigated first time by this study. 相似文献
10.
Layiq Zia G. Hassnain Jaffari Jamil Ur Rahman Soonil Lee S. Ismat Shah 《Physics letters. A》2019,383(26):125835
The effect of thermal quenching on physical properties of morphotropic phase boundary BiFeO3-0.35PbTiO3 composition, composed of Pnma, R3c and P4mm phases, has been investigated in detail. We detected and quantified role of quenching through investigation of magnetic, dielectric and ferroelectric anomalies. Quenching significantly i) enhances the tetragonal phase percentage (hence affects domain structure), ii) reduces domain wall clamping with a large increase in electrical polarization, iii) increases magnetization at the structural phase transition temperature (tunable magneto-electric coupling), iv) magnifies intrinsic property i.e. intra grain relaxation dynamics (which are otherwise suppressed due to the pinning of the defect dipoles), etc. All these findings clearly verify the role of quenching which noticeably enhances multiferroic properties at the well-known morphotropic phase boundary. 相似文献