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31.
The grafting of acrylic acid onto electron beam‐irradiated polypropylene was carried out using preirradiation method. The stability of peroxy radicals was investigated by electron spin resonance. It was found that the decay of peroxy radicals is much faster at 70°C than at 40°C and ambient temperature. The grafting has been observed to be strongly dependent on the monomer dilution in the reaction medium. The grafting was ascertained by attenuated total reflectance (ATR). The distribution of grafts across the samples was monitored by infrared microscopy. It was found that the graft management is considerably influenced by composition of the grafting medium. The grafting involving pure monomer leads to the surface enrichment with the polyacrylic acid chains. The samples grafted in pure monomer led to much lower contact angles as compared to the diluted monomer solution. The swelling of the grafted samples also showed a trend that was governed by the graft management. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 546–553, 2006 相似文献
32.
Recently, Diabaté et al. [Diabaté, L., Blanc, Ph., Wald, L., 2004. Solar climate in Africa. Solar Energy 76, 733–744] created a map of solar radiation climate in Africa using clearness index for 62 sites. They established a solar climate class II located in Malawi and Madagascar. However, their analysis did not include any irradiation data from a site in Malawi. In this study, the solar radiation climate of Malawi has been studied using long-term global radiation data from a local site. The mean monthly (Ktm) and seasonal (Kts) daily clearness indices for the site were computed. It is observed that Ktm has two maxima in a year (Ktm = 0.58 in May and Ktm = 0.64 in September), in close conformity with findings of Diabaté et al. (2004). Other results are presented and discussed. 相似文献
33.
Poly(vinylbenzyltrimethylammonium chloride)‐graft‐cotton cellulose, an anion‐exchange matrix, was synthesized by a mutual radiation‐induced grafting technique with a 60Co γ‐radiation source. The grafted matrix was characterized by grafting yield estimation, elemental analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The grafting yield decreased with the increase in the dose rate. However, the grafting yield and nitrogen content of grafted samples increased almost linearly with an increase in the total irradiation dose. To evaluate the performance of the grafted anion‐exchange matrix, the protein adsorption and elution behavior were investigated in a continuous column process under various experimental conditions, with bovine serum albumin used as a model protein. The binding and elution behavior of the anion‐exchange matrix depended on different experimental parameters, such as the grafting yield, ionic strength, pH of the medium, and amount of protein loaded. From a breakthrough curve, the equilibrium binding capacity and elution percentage of the grafted anion‐exchange matrix were estimated to be 40 mg/g and 94%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5512–5521, 2006 相似文献
34.
Chongbin Zhao Tianyun Liu 《International journal for numerical methods in engineering》2003,58(10):1435-1456
This paper presents an exact non‐reflecting boundary condition for dealing with transient scalar wave propagation problems in a two‐dimensional infinite homogeneous layer. In order to model the complicated geometry and material properties in the near field, two vertical artificial boundaries are considered in the infinite layer so as to truncate the infinite domain into a finite domain. This treatment requires the appropriate boundary conditions, which are often referred to as the artificial boundary conditions, to be applied on the truncated boundaries. Since the infinite extension direction is different for these two truncated vertical boundaries, namely one extends toward x →∞ and another extends toward x→‐ ∞, the non‐reflecting boundary condition needs to be derived on these two boundaries. Applying the variable separation method to the wave equation results in a reduction in spatial variables by one. The reduced wave equation, which is a time‐dependent partial differential equation with only one spatial variable, can be further changed into a linear first‐order ordinary differential equation by using both the operator splitting method and the modal radiation function concept simultaneously. As a result, the non‐reflecting artificial boundary condition can be obtained by solving the ordinary differential equation whose stability is ensured. Some numerical examples have demonstrated that the non‐reflecting boundary condition is of high accuracy in dealing with scalar wave propagation problems in infinite and semi‐infinite media. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
35.
Simulation and investigation of the effect of an isolated jump on realization of the unit of power of laser radiation and dissemination of the size of the unit are considered. Results are obtained by means of a newly developed algorithm that characterizes the behavior of the mean value of a signal and the standard deviation of a system as functions of the parameters of a jump in the power of laser radiation and the length and amplitude of the jump. If information concerning the time when a jump occurs is available, the proposed algorithm makes it possible to take into account how a jump affects the ultimate result of a measurement. 相似文献
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38.
Methods for the production of mutants of the cellulase producer Clostridium cellulolyticum ATCC 35319 were examined using an agar plate screening technique. Spontaneous and UV light-induced mutants were isolated, some of which exhibited a high level of both endoglucanase and exoglucanase activities as assayed using CMC (carboxymethyl cellulose) and PNPCb (paranitrophenyi-β-cellobioside) respectively. The volumetric enzyme activities were up to 2.5 times those of the wild strain. 相似文献
39.
Nonionic organic contaminants such as phenol, benzene, and toluene from contaminated wastewater on laboratory scale can be effectively sorbed by cellulosic wood pulp sheet incorporated with three polar functional groups. The synthesis was carried out by graft copolymerization reaction of N,N‐dimethylaminoethylmethacrylate with methacrylic acid onto wood pulp. The preparation conditions at which the grafting process proceeds homogeneously are determined. Characterization and some selected properties of the original and grafted wood pulp were evaluated using FTIR and scanning electron microscope, also, the removal of phenol, benzene, and toluene on laboratory scale was investigated by using gas chromatography. It was found that phenol shows the highest removal percent than that of benzene and toluene. The efficiency of removal of the nonionic contaminants is found to be 97%, which shows a great promise for its applicability in the removal of organic contaminates from wastewater. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3589–3595, 2006 相似文献
40.
PV system sizing using observed time series of solar radiation 总被引:4,自引:0,他引:4
Sizing represents an important part of photovoltaic system design. This paper describes a sizing procedure based on the observed time series of solar radiation. Using a simple geometrical construction, the sizing curve is determined as a superposition of contributions from individual climatic cycles of low daily solar radiation. Unlike the traditional methods based on loss-of-load probability, the reliability of supply enters in this method through the length of the time series of data used in the analysis. The method thus resembles techniques used in other branches of engineering where extreme values are considered as functions of certain recurrence intervals. 相似文献