Emission of trace toxic metals during pulverized fuel combustion of Czech coals

A study of the trace elements emission (As, Se, Cd, Co, Cr, Cu, Zn, Hg, Tl, Pb, Ni, Sn, Sb, V, Mn and Fe) from pulverized coal combustion has been made at six heating and power stations situated in the Czech Republic. The amount of chlorine in coal has considerable influence on volatilization of some elements such as Zn, Cu, Pb, Hg and Tl, which is explained by the formation of thermodynamically stable compounds of these elements with chlorine. Generally, the affinities for Cl follows the order Tl > Cu > Zn > Pb > Co > Mn > Sn > Hg. The experimental data indicates enrichment of some of the trace toxic elements in the emissions (Cu, Zn, As, Se, Cd, Sn, Sb, Hg and Pb) and good agreement was obtained by thermodynamic equilibrium calculations with a few exceptions. In the case of Fe, Mn, Co, Cr and Sn calculated values are overestimated in the bottom ash and there are zero predicted amounts of these elements in the fly ash. In comparison, the results from experiments show up to 80% of these elements retained in fly ash. This implies that there exist additional steps leading to the enrichment by Fe, Mn, Co, Cr and Sn of small particles. Such mechanisms could include the ejection during devolatilization of small inorganic particles from the coal of bottom ash particles, or disintegration of the char containing these metals to small particles of fly ash. On the other hand, there are slightly overestimated or similar values of relative enrichment factors for As, V, Cu, Cd, Sb, Tl and Pb in the fly ashes and zero predicted values for bottom ashes. Our experimental results show about 5% or less of these elements are retained in bottom ashes, so they probably remain in the bottom ash inside unburned parts of coal. Copyright © 2003 John Wiley & Sons, Ltd.     

A new way for constructing high accuracy shock-capturing generalized compact difference schemes

The generalized compact (GC) schemes and some of their important properties are presented. And a new way for constructing high order accuracy and high-resolution GC schemes is presented. The schemes constructed by using this way could satisfy some principles and demands prescribed in advance to ensure some desired properties to the schemes, such as the principle about suppression of the oscillations, the principle of stability, the order of accuracy and number of scheme points, etc. As two examples, a three-point third-order compact scheme and a three-point fifth-order GC scheme satisfying the principle about suppression of the oscillations and the principle of stability are described in this paper. Numerical results show that these schemes are shock-capturing. The time-dependent boundary conditions proposed by Thompson are well employed when the algorithm is applied to the Euler equations of gas dynamics. Fourier analysis shows that the resolution characteristics are spectral-like.     

Influence of aminophylline and 8-(p-sulfophenyl)theophylline on the anticonvulsive action of diphenylhydantoin, phenobarbital, and valproate against maximal electroshock-induced convulsions in mice

Time variation of drinking is substantial and has an effect on aggregate estimates of consumption. In this article it is shown that because of a considerable seasonal variation in consumption (+/- 20%) a serious bias in annual consumption estimates can be expected in surveys with a limited time frame. The present study analyzes drinking data collected in the general population of the Netherlands from March 1985 through December 1985 (including Christmas and New Year's Eve). Since it was expected that sensitivity to temporal fluctuations might not be equal for different methods of measurement, several indices of consumption were compared. Although the assessed seasonal effect varies indeed across types of measurement, across male and female subsample and across types of alcoholic beverage, the general tendency is for consumption to be highest in the spring season and lowest in the autumn. Sales figures fluctuate accordingly. It is evident that the risk of biased estimates is larger the shorter the time frame of the survey. Seasonal variation was highest in the frequency domain. Furthermore, exclusion from the time frame of collective holidays, during which people drink more often and more per occasion (viz., Christmas), increases the risk of biased estimates. Even estimates of abstention, but also regular heavy drinking among women, appear to vary considerably over the three seasons in this study. The main conclusion is that results of comparisons of survey data on drinking, particularly those over time, are more or less invalid if the respective time frames of the surveys do not correspond.     

Evaluation of factors influencing platelet aggregation in patients with chronic glomerulonephritis (CGN)

Platelets (PLT) play an important role in hemostasis, modulation of immunological and inflammatory processes. There is also evidence that PLT takes part in the development of atherosclerosis and glomerulosclerosis. The aim of presented study was to determine morphological and functional changes of platelets and their relation to the lipid, protein and coagulation factors disturbances in patients with chronic glomerulonephritis (CGN). The studies were carried out in 60 patients with CGN diagnosed by renal biopsy: 30 patients without nephrotic syndrome (NS)-CGN and 30 patients with NS-CGN+NS. Protein and lipid disturbances, coagulation factors were estimated using routine laboratory methods. Platelet count (PLT), mean platelet volume (MPV) and modal platelet volume (PLT-Mode) were measured using Technicon H1 hematological autoanalyser. Platelet function was assessed by aggregometry using turbidimetric method (inductors: ADP 1-3 microM, collagen 50g/ml, epinephrine 0.25-5 microM). Spontaneous platelet aggregation (SPA) was measured in platelet rich plasma (PRP) without inductors for 15 min, in 1-2 hours after venesection. SPA was observed in 9 of 30 patients with CGN and in 19 of 30 patients with CGN+NS. MPV and PLT Mode were significantly higher in patient showing SPA compared with those without. Significant correlations between SPA and the concentration of plasma albumin (r = -0,70; p < 0.02) TG and CH-LDL (r = 0,61; p < 0.05) were found in CGN+NS patients. APTT was significantly shorter in patients showing SPA compared with those without and negative significant correlation between SPA and APTT was found. Platelet aggregation to inductors in CGN and CGN+NS patients was diminished compared with control group. Lack of second phase aggregation in response to aggregation inducers was observed in patients with SPA. Conclusions. 1. Platelet hyperaggregation play an important role in hypercoagulation state in CGN patients. 2. SPA in vitro was observed in majority of CGN+NS patients and in some without NS. 3. Pathomechanism of SPA is probably multifactorial (hypoalbuminemia, dyslipidemia, changes in concentration of coagulation parameters).     

Evidence for interaction between transmembrane segments in assembly of Kv1.3

Previously, we showed that the N-terminal recognition domain (T1) of Kv1.3 was not required for assembly of functional channels [Tu et al. (1996) J. Biol. Chem. 271, 18904-18911]. Moreover, specific Kv1.3 peptide fragments including regions of the central core are able to inhibit expression of current produced from a channel lacking the T1 domain, Kv1.3(T1-). To elucidate the mechanism whereby Kv1.3 peptide fragments suppress Kv1.3(T1-) current, we have studied the ability of peptide fragments containing the transmembrane segments S1, S1-S2, or S1-S2-S3 to physically associate with the Kv1.3(T1-) polypeptide subunit in vitro in microsomal membranes. Using c-myc (9E10) epitope-labeled peptide fragments and anti-myc antibody as well as antisera to the Kv1.3 C-terminus, we now demonstrate specific association of these peptide fragments with Kv1.3(T1-). Association of peptide fragments with Kv1.3(T1-) was correlated with integration of both proteins into the membrane. Furthermore, the relative strength and kinetics of this association directly correlated with the ability of fragments to suppress Kv1.3(T1-) current. The rate-limiting step in the sequential synthesis, integration, and formation of a complex was the association of integrated polypeptides within the plane of the lipid bilayer. These results strongly suggest that the physical association of transmembrane segments provides the basis for suppression of K+ channel function by K+ channel peptide fragments in vivo. Moreover, the S1-S2-S3 peptide fragment potently suppressed full-length Kv1.3, thus implicating a role for the S1-S2-S3 region of Kv1.3 in the assembly of the Kv1.3 channel. We refer to these putative association sites as IMA (intramembrane association) sites.     

Mesopore development in PAN-ACF resulting from non-metal additives

The narrow pore-size distribution of activated carbon fibres (ACF) limits their application in the fields concerning larger molecules, such as liquid adsorption and catalyst support. On the addition of carbon particles and organic materials to polyacrylonitrile fibres, and after stabilizing and activating, the mesoporosity in the resultant ACF has been obviously increased. Among these additives, carbon black gives the best effect. With 1 wt% carbon black I in precursor and on activating at 880°C for 30 min, a mesoporosity of 48.2% (total pore volume 0.704 ml g-1, mesopore volume 0.340 ml g-1) has been obtained. The mechanism of mesopore formation is also discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

The cholinergic system in Alzheimer's disease

The past decade has witnessed an enormous increase in our knowledge of the variety and complexity of neuropathological and neurochemical changes in Alzheimer's disease. Although the disease is characterized by multiple deficits of neurotransmitters in the brain, this overview emphasizes the structural and neurochemical localization of the elements of the acetylcholine system (choline acetyltransferase, acetylcholinesterase, and muscarinic and nicotinic acetylcholine receptors) in the non-demented brain and in Alzheimer's disease brain samples. The results demonstrate a great variation in the distribution of acetylcholinesterase, choline acetyltransferase, and the nicotinic and muscarinic acetylcholine receptors in the different brain areas, nuclei and subnuclei. When stratification is present in certain brain regions (olfactory bulb, cortex, hippocampus, etc.), differences can be detected as regards the laminar distribution of the elements of the acetylcholine system. Alzheimer's disease involves a substantial loss of the elements of the cholinergic system. There is evidence that the most affected areas include the cortex, the entorhinal area, the hippocampus, the ventral striatum and the basal part of the forebrain. Other brain areas are less affected. The fact that the acetylcholine system, which plays a significant role in the memory function, is seriously impaired in Alzheimer's disease has accelerated work on the development of new drugs for treatment of the disease of the 20th century.