A theory based on a rigid sphere model is presented for the diffusion coefficient of dissolved gases (and liquids) in protein solutions. The only quantities needed in order to make calculations are the rigid sphere diameters and the solution density; methods are given for obtaining the diameters. The theory predicts that the ratio of the diffusion coefficient of the gas in protein solution to that in pure water is strongly dependent on the size of the protein molecule, but is insensitive to the properties of the solute gas. The theory gives good agreement with available experimental data for the effects of protein concentration and molecular properties on the diffusion coefficient. 相似文献
Photochromic colorants change rapidly and reversibly from colorless to colored state when activated by ultraviolet radiation. They can be applied on textile substrates with use of organic binders. Different type of binders and their concentration may have a significant effect on color development and other related properties. In this work, a study of the effect of binder type at different concentrations on the color development, wash fastness and some comfort characteristics is undertaken. It was found that while these properties vary with binder type and concentration, the best color development is obtained at an optimum concentration of 5% binder. The presence of binder may affect comfort related properties of the fabrics, such as stiffness, water absorbency, air permeability, sometimes quite adversely. Hence a careful selection of the binder type is needed depending on the most important requirement in the colored fabrics. 相似文献
The present work involves the prediction of the concentration profiles in the case of pyrolysis of different lignocellulosic materials in isothermal and non-isothermal conditions. The operative temperature range is from 573 to 973 K for isothermal conditions, and for non-isothermal conditions, the heating rate ranges from 5 to 80 K/min (5, 20, 40, 60 and 80 K/min).
The concentration for the above mentioned conditions is predicted for various biomass components, viz. cellulose, hemicellulose and lignin. Based on the concentration profiles of different biomass materials, it is possible to predict the pyrolysis behavior over a wide range of temperatures under isothermal and non-isothermal conditions for a large number of biomass materials, provided the activation energy and the frequency factor for the various reaction steps are known. It is also possible to ascertain the degree of combustibility of different biomass materials.
The simulation model utilizes a 4th order Runge-Kutta Predictor-Corrector method to solve the coupled ordinary differential equations. Based on thermogravimetric analysis done elsewhere, it is considered that temperature and time have a linear relationship. The above technique enables us to predict concentration profiles of different biomass materials for the entire range of pyrolysis. The concentration vs time data is plotted graphically for both isothermal and non-isothermal conditions utilizing the Harvard Graphics package on a PC-A/T personal computer. 相似文献
Photoacoustic imaging of living subjects offers higher spatial resolution and allows deeper tissues to be imaged compared with most optical imaging techniques. As many diseases do not exhibit a natural photoacoustic contrast, especially in their early stages, it is necessary to administer a photoacoustic contrast agent. A number of contrast agents for photoacoustic imaging have been suggested previously, but most were not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes conjugated with cyclic Arg-Gly-Asp (RGD) peptides can be used as a contrast agent for photoacoustic imaging of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times greater photoacoustic signal in the tumour than mice injected with non-targeted nanotubes. These results were verified ex vivo using Raman microscopy. Photoacoustic imaging of targeted single-walled carbon nanotubes may contribute to non-invasive cancer imaging and monitoring of nanotherapeutics in living subjects. 相似文献
Wireless Networks - Wireless Mesh Networks (WMNs) have evolved into a wireless communication technology of immense interest. But technological advancements in WMNs have inadvertently spawned a... 相似文献
Finite element analysis has been carried out to obtain temperature dependent transversely isotropic properties of the single-walled carbon nanotubes (SWCNTs). Finite element models of SWCNTs are generated by specifying the C–C bond rigidities. The five independent transversely isotropic properties for different chiralities are evaluated using the stress fields of thick-walled cylinders and the elastic deformations of SWCNTs subjected to pure extension, internal pressure and pure torsion loads. Empirical relations are provided for the five independent elastic constants useful to armchair and zigzag SWCNTs. 相似文献
Somatostatin (SST) exerts direct antiproliferative effects in tumor cells, triggering either growth arrest or apoptosis. The cellular actions of SST are transduced through a family of five distinct somatostatin receptor subtypes (SSTR1-5). Whereas growth inhibition has been reported to follow stimulation of protein tyrosine phosphatase via SSTR2 or inhibition of Ca2+ channels via SSTR5 in heterologous expression systems, the subtype selectivity for signaling apoptosis has not been investigated. The tumor suppressor protein p53 and the protooncogene product c-Myc regulate cell cycle progression (growth factors present) or apoptosis (growth factors absent). The p53-induced G1 arrest requires induction of p21, an inhibitor of cyclin-dependent kinases, whereas apoptosis requires induction of Bax. c-Myc is capable of abrogating p53-induced G1 arrest by interfering with the inhibitory action of p21 on cyclin-dependent kinases. We have, therefore, investigated the regulation of p53, p21, c-Myc, and Bax and cellular apoptosis in relation to cell cycle progression in CHO-K1 cells stably expressing individual human SSTR1-5. We demonstrate that apoptosis is signaled uniquely through human SSTR3 and is associated with dephosphorylation-dependent conformational change in wild-type (wt) p53 as well as induction of Bax. The induction of wt p53 occurs rapidly and precedes the onset of apoptosis. We show that the increase in wt p53 is not associated with the induction of p21 or c-Myc when octreotide-induced apoptosis becomes evident, suggesting that such apoptosis does not require G1 arrest and is not c-Myc dependent. These findings provide the first evidence for hormonal induction of wt p53-associated apoptosis via G protein-coupled receptor in a subtype-selective manner. 相似文献
We consider a zero-sum mutual information game on multiple-input multiple-output (MIMO) Gaussian Rayleigh-fading channels. The players are an encoder-decoder pair as the maximizer, and a jammer as the minimizer, of the mutual information between the input and the output of the channel. There are total power constraints on both the jammer and the encoder. Also, the jammer has access to the encoder output. We find the unique saddle point of this game, and prove the somewhat surprising result that the knowledge of the channel input is useless to the jammer. 相似文献