Formation and stabilization of combustion-generated environmentally persistent free radicals on an Fe(III)2O3/silica surface

Previous studies have shown environmentally persistent free radicals (EPFRs) form when chlorine- and hydroxy-substituted benzenes chemisorb on Cu(II)O-containing surfaces under postcombustion conditions. This paper reports the formation of EPFRs on silica particles containing 5% Fe(III)(2)O(3). The EPFRs are formed by the chemisorption of substituted aromatic molecular adsorbates on the metal cation center followed by electron transfer from the adsorbate to the metal ion at temperatures from 150 to 400 °C. Depending on the nature of the adsorbate and the temperature, two organic EPFRs were formed: a phenoxyl-type radical, which has a lower g-value of 2.0024-2.0040, and a second semiquinone-type radical, with a g-value of 2.0050-2.0065. Yields of EPFRs were ～10× lower for iron than copper; however, the half-lives of EPFRs on iron ranged from 24 to 111 h, compared to the half-lives on copper of 27 to 74 min. The higher oxidation potential of Fe(III)(2)O(3) is believed to result in greater decomposition of the adsorbate, resulting in the lower EPFR yields, but increased stabilization of the EPFR once formed, resulting in the longer half-lives.     

Infiltration of highly aligned carbon nanotube arrays with molten polystyrene

Highly aligned carbon nanotube/polystyrene (HACNT/PS) composites were prepared conveniently via polymer impregnation of aligned arrays, avoiding conventional solution or melt processes that involve high-shear blending. Detailed scanning electron microscopy (SEM), X-Ray diffraction (XRD) and differential scanning calorimetry (DSC) studies show that the alignment of the multi-wall nanotubes is retained after polymer impregnation. A range of key parameters were investigated, including the amount of molten polymer required for complete infiltration, the maximum mass fraction of CNTs in dense composites, and the effect of CNTs on the glass transition temperature (T_g) of the polymer. This approach may be adapted to the fabrication of large scale, highly anisotropic, thin or multilayer CNT composites using other molten polymers.     

Absorbing the Rapid Growth of Shopping Centres in Poland after the Political Change

The aim of this paper is to present the development of shopping centres in Poland after its political transition. From that time, all types of shopping centres were built, starting from the very basic first generation and developing into the most current formats. In the article, types of shopping centres are compared to their western origins. Planning laws and procedures that apply to the processes are also described, with an example of a law that was introduced to specifically control growth of shopping centres. Apart from that current trends and growth possibilities in the present market situation are discussed. As a result, a very rapid development process was observed, with little hampering from the planning policies. This may be used as a point of reference for other countries that have not yet encountered that process.     

Pruning backpropagation neural networks using modern stochastic optimisation techniques

Approaches combining genetic algorithms and neural networks have received a great deal of attention in recent years. As a result, much work has been reported in two major areas of neural network design: training and topology optimisation. This paper focuses on the key issues associated with the problem of pruning a multilayer perceptron using genetic algorithms and simulated annealing. The study presented considers a number of aspects associated with network training that may alter the behaviour of a stochastic topology optimiser. Enhancements are discussed that can improve topology searches. Simulation results for the two mentioned stochastic optimisation methods applied to non-linear system identification are presented and compared with a simple random search.     

Performance of Connectionless Data Service in High Density Microcell

Two categories of commercial wireless packet services exist today – a standalone system where the entire bandwidth is dedicated to the transmission of data packets (e.g. ARDIS, Mobitex), and an overlay system, where the unused channels of an existing cellular phone system are used (e.g. CDPD, GPRS). This paper examines the performance of the overlay service in a high density Manhattan street grid microcell. This type of cell is common in central urban areas. A simple analytical model is derived to describe the channel occupancy distribution in the microcell. The model is used to examine the performance of CDPD, a connectionless data service operating over a cellular system. Throughput and latency are evaluated under the two existing channel assignment schemes currently in use. A new assignment scheme is proposed, and is found to give better performance with minimal changes to the CDPD specification.     

Normalization of periodontal tissues in osteopetrotic mib mutant rats, treated with CSF-1

Acute renal failure is a serious complication of pregnancy. Over the past few decades, the overall incidence of acute renal failure in pregnancy has decreased in Western societies. In less developed countries, the incidence of acute renal failure in pregnancy has remained high. This retrospective study examined the incidence, morbidity, fetomaternal mortality, and renal prognosis among pregnant inner-city patients. Serum creatinine levels of all pregnant patients seen at an inner-city hospital from January 1986 to December 1996 were reviewed. Twenty-one consecutive cases of acute renal failure were identified for an incidence of 2 in 10,000 pregnancies. Maternal mortality was high (15.7%) as was morbidity, with a tendency toward a high rate of intrauterine fetal growth retardation. These results suggest that the outlook for acute renal failure in inner-city patients is dismal in sharp contrast to the prognosis for other patient groups with acute renal failure in pregnancy in Western societies. Preventive strategies should be aimed at this subpopulation with a view to improving early prenatal care as well as enhancing overall access to the health-care system.     

Effect of immune activation on the dynamics of human immunodeficiency virus replication and on the distribution of viral quasispecies

Virus replication in a human immunodeficiency virus (HIV)-infected individual, as determined by the steady-state level of plasma viremia, reflects a complex balance of viral and host factors. We have previously demonstrated that immunization of HIV-infected individuals with the common recall antigen, tetanus toxoid, disrupts this steady state, resulting in transient bursts of plasma viremia after immunization. The present study defines the viral genetic basis for the transient bursts in viremia after immune activation. Tetanus immunization was associated with dramatic and generally reversible shifts in the composition of plasma viral quasispecies. The viral bursts in most cases reflected a nonspecific increase in viral replication secondary to an expanded pool of susceptible CD4(+) T cells. An exception to this was in a patient who harbored viruses of differing tropisms (syncytium inducing and non-syncytium inducing [NSI]). In this situation, immunization appeared to select for the replication of NSI viruses. In one of three patients, the data suggested that immune activation resulted in the appearance in plasma of virus induced from latently infected cells. These findings illustrate certain mechanisms whereby antigenic stimulation may influence the dynamics of HIV replication, including the relative expression of different viral variants.     

Synthesis of solid epoxy resins base on BPC II and bisphenol A using conventional heating equipment and microwave

New solid state epoxy resins based on diglycidyl ether of 1,1‐dichloro‐2,2 bis (4‐hydroxyphenyl), ethylene (BPC) and BPA epoxy resins in the reaction with BPC and BPA were developed. Solid epoxy resins were synthesised by the use of two different heating methods: conventional and microwave reactor. The use of microwave radiation as novel heating medium as an alternative to the conventional methods, which provide a quicker and more effective synthesis. The solid epoxies have high melting points higher than 100°C and the polycondensation degree remains between n = 4–12. Epoxy value stays low and occurs around 0,02–0,1. BPA epoxy resins and diglycidylether of BPC II were compared in terms of reaction speed. It can be seen that the reaction of BPC diglycidylether occurs approximately 20% quicker given the same reaction conditions of temperature, and balance of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3850–3854, 2006