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排序方式: 共有1131条查询结果,搜索用时 31 毫秒
71.
Priyadarsini Sreenivasan Jijo Wilson Prabha Damodaran Nair Lynda Velutheril Thomas 《先进技术聚合物》2020,31(5):1139-1149
This work reports a novel fabrication technique for development of channels on paper‐based microfluidic devices using the syringe module of a 3D printing syringe–based system. In this study, printing using polycaprolactone (PCL)‐based ink (Mw 70 000‐90 000) was employed for the generation of functional hydrophobic barriers on Whatman qualitative filter paper grade 1 (approximate thickness of 180 μm and pore diameter of 11 μm), which would effectively channelize fluid flow to multiple assay zones dedicated for different analyte detection on a microfluidic paper‐based analytical device (μPAD). The standardization studies reveal that a functional hydrophilic channel for sample conduction fabricated using the reported technique can be as narrow as 460.7 ± 20 μm and a functional hydrophobic barrier can be of any width with a lower limit of about 982.2 ± 142.75 μm when a minimum number of two layers of the ink is extruded onto paper. A comparison with the hydrodynamic model established for writing with ink is used to explain the width of the line printed by this system. A fluid flow analysis through a single channel system was also carried out to establish its conformity with the Washburn model, which governs the fluid flow in two‐dimensional μPAD. The presented fabrication technique proves to be a robust strategy that effectively taps the advantages of this 3D printing technique in the production of μPADs with enhanced speed and reproducibility. 相似文献
72.
On Regularization of a Source Identification Problem in a Parabolic PDE and its Finite Dimensional Analysis
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Subhankar Mondal & M. Thamban Nair 《偏微分方程(英文版)》2021,34(3):240-257
We consider the inverse problem of identifying a general source term, which is a function of both time variable and the spatial variable, in a parabolic PDE from the knowledge of boundary measurements of the solution on some portion of the lateral boundary. We transform this inverse problem into a problem of solving a compact linear operator equation. For the regularization of the operator equation with noisy data, we employ the standard Tikhonov regularization, and its finite dimensional realization is done using a discretization procedure involving the space $L^2(0,\tau;L^2(Ω))$. For illustrating the specification of an a priori source condition, we have explicitly obtained the range space of the adjoint of the operator involved in the operator equation. 相似文献
73.
C. A. Estrada E. A. Meyers R. A. Zingaro D. C. Dufner P. K. Nair M. T. S. Nair 《Heteroatom Chemistry》1995,6(4):349-354
The reaction between thin films of CdSe and aqueous HgCl2 was studied using electron diffraction (ED) powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was found that α-Hg3Se2Cl2 is formed in the CdSe film following its reaction with 0.01 M HgCl2 for a period of 5 minutes. Upon completion of the reaction of CdSe powder with 0.01 M HgCl2, Hg2Cl2 is present in addition to α-Hg3Se2Cl2 in a molar ratio of 1:3.1. The effect of air annealing on CdSe powder was also studied. Heating in air to 450°C for 1 hour resulted in an XRD pattern corresponding to the hexagonal form of CdSe. 相似文献
74.
Peptide synthesis in aqueous environments: the role of extreme conditions and pyrite mineral surfaces on formation and hydrolysis of peptides 总被引:1,自引:0,他引:1
Schreiner E Nair NN Wittekindt C Marx D 《Journal of the American Chemical Society》2011,133(21):8216-8226
A comprehensive study of free energy landscapes and mechanisms of COS-mediated polymerization of glycine via N-carboxy anhydrides (NCAs, "Leuchs anhydrides") and peptide hydrolysis at the water-pyrite interface at extreme thermodynamic conditions is presented. Particular emphasis is set on the catalytic effects of the mineral surface including the putative role of the ubiquitous sulfur vacancy defects. It is found that the mere presence of a surface is able to change the free energetics of the elementary reaction steps. This effect can be understood in terms of a reduction of entropic contributions to the reactant state by immobilizing the reactants and/or screening them from bulk water in a purely geometric ("steric") sense. Additionally, the pyrite directly participates chemically in some of the reaction steps, thus changing the reaction mechanism qualitatively compared to the situation in bulk water. First, the adsorption of reactants on the surface can preform a product-like structure due to immobilizing and scaffolding them appropriately. Second, pyrite can act as a proton acceptor, thus replacing water in this role. Third, sulfur vacancies are found to increase the reactivity of the surface. The finding that the presence of pyrite speeds up the rate-determining step in the formation of peptides with respect to the situation in bulk solvent while stabilizing the produced peptide against hydrolysis is of particular interest to the hypothesis of prebiotic peptide formation at hydrothermal aqueous conditions. Apart from these implications, the generality of the studied organic reactions are of immediate relevance to many fields such as (bio)geochemistry, biomineralization, and environmental chemistry. 相似文献
75.
A class of new benchmark deformational flow test cases for the two-dimensional horizontal linear transport problems on the sphere is proposed. The scalar field follows complex trajectories and undergoes severe deformation during the simulation; however, the flow reverses its course at half-time and the scalar field returns to its initial position and shape. This process makes the exact solution available at the end of the simulation, and facilitates assessment of the accuracy of the underlying transport scheme. A procedure to eliminate possible cancellations of errors when the flow reverses is proposed. 相似文献
76.
Nair Supriya Aswathy UV Mathew Ann Raghavan Rajeev 《Journal of Thermal Analysis and Calorimetry》2017,128(3):1731-1741
Journal of Thermal Analysis and Calorimetry - Thermal decomposition, thermal conductivity, specific heat and flammability of polydimethyl siloxane (PDMS) resin and three PDMS-based systems with... 相似文献
77.
Deepa Sathian Rupali Rohatgi V. Jayalakshmi P. K. Marathe Sarala Nair R. V. Kolekar G. Chourasiya S. Kannan 《Indian Journal of Physics》2009,83(6):863-869
CR-39 Solid State Nuclear Track Detecting foils (SSNTD), along with 1 mm thick polyethylene radiator, sealed in triple laminated
pouches, are used for country wide Fast Neutron Personnel Monitoring in India. With the present system of processing by elevated
temperature electrochemical etching (ETECE) and evaluation using automatic image analysis, only 16 foils are processed at
a time and it is useful over the dose equivalent range 0.2 mSv to 10 mSv. It has been reported that, by processing CR-39 of
good detection efficiency by chemical etching at elevated temperature, more numbers of foils can be processed simultaneously.
In the present study, CR-39 foils from Pershore Moulding (UK) have been chemically etched using 7 N KOH under various conditions
of temperature and etching durations and evaluated using high magnification microscope. The duration of chemical etching,
has been optimized at a constant temperature of 60°C for chemical etching process. The characteristics of the chemically etched
CR-39 foils are compared with the characteristics of the CR-39 foils processed by the existing system of ETECE and the detailed
results are presented in the full text of the paper. It has been observed that by chemical etching process, the dose equivalent
range of CR-39 foils can be extended above 60 mSv.
相似文献
78.
Guy Patchornik Irishi N.N. NamboothiriDivya K. Nair Ellen WachtelSidney R. Cohen Noga FriedmanMordechai Sheves 《Journal of colloid and interface science》2012,388(1):300-305
A strategy for clustering of native lipid membranes is presented. It relies on the formation of complexes between hydrophobic chelators embedded within the lipid bilayer and metal cations in the aqueous phase, capable of binding two (or more) chelators simultaneously Fig. 1. We used this approach with purple membranes containing the light driven proton pump protein bacteriorhodopsin (bR) and showed that patches of purple membranes cluster into mm sized aggregates and that these are stable for months when incubated at 19 °C in the dark. The strategy may be general since four different hydrophobic chelators (1,10-phenanthroline, bathophenanthroline, Phen-C10, and 8-hydroxyquinoline) and various divalent cations (Ni2+, Zn2+, Cd2+, Mn2+, and Cu2+) induced formation of membrane clusters. Moreover, the absolute requirement for a hydrophobic chelator and the appropriate metal cations was demonstrated with light and atomic force microscopy (AFM); the presence of the metal does not appear to affect the functional state of the protein. The potential utility of the approach as an alternative to assembled lipid bilayers is suggested. 相似文献
79.
[reaction: see text]. A facile one-pot synthesis of 1-amino-4-aryl-tetralin derivatives by the CAN-induced cyclodimerization of various styrenes in acetonitrile and acrylonitrile is described. 相似文献
80.
Suppose denote the ergodic averages for the natural numbers . Let denote the corresponding maximal function and let for . We show that for if there exists such that then there exists such that . Similar weak (1,1) inequalities follow for V
q
when you know them for M too also with q > 1. We also show this fails completely if q= 1. We also show that for certain polynomial like and random sequences , if
and
is of exponential growth then
for a certain positive constant C.
(Received 11 February 1998; in revised form 10 December 1998) 相似文献