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EN
A rapid, sensitive and simple reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of acyclovir (ACV) in rabbit plasma. BDS C18 column was used to conduct analysis using ammonium dihydrogen phosphate buffer (50mM) and methanol as mobile phase (98:2), with pH adjusted to 2.5 using orthophosphoric acid. Flow rate was kept at 1 mL/min. Selective precipitation of plasma proteins were done by adding 5% perchloric acid. Precipitated plasma proteins were separated by centrifugation. ACV moves in a supernatant, which was snapped and passed through a syringe filtration assembly. Direct injection of supernatant was given into a BDS C18 column and ACV was detected at 256 nm. The limit of detection for ACV in plasma was estimated as 15ng/mL whereas the limit of quantitation was calculated as 25 ng/mL. Moreover, the developed method has been found to be selective and linear into concentration range of 25 – 2000 ng/mL. The present method could be successfully applied to samples from bioavailability and bioequivalence studies.
EN
This paper describes the investigation of the influence of target material atomic number (Z) on the laser-produced plasma pressure. For this reason, several target materials representing a wide range of atomic numbers (Z = 3.5 - 73), i.e. plastic (CH), Al, Cu, Ag, and Ta, were used. The results presented show that the plasma pressure decreases with growing atomic number but in a limited range of Z only. For higher Z, starting approximately from Z = 47 (Ag), the plasma pressure becomes constant, as confirmed by interferometric measurements and x-ray plasma imaging.
Open Medicine
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2006
|
vol. 1
|
issue 1
23-34
EN
Serum contains various antioxidant molecules that may provide important protection against free radical attack. The aim of this work was to assess the total antioxidant capacity of plasma and a marker of lipid per oxidation [(thiobarbituric acid-reactive substances (TBARS)] in plasma of healthy smoking and non-smoking young and elderly subjects. In addition, we investigated plasma concentrations of α-tocopherol, β-carotene, and ascorbic acid. In in vitro experiments, the effects of exogenous compounds (ascorbic acid, uric acid, Trolox) on total ferric-reducing activity of plasma (FRAP) were also tested. We demonstrated that total antioxidant capacity of plasma obtained from healthy non-smoking young subjects was significantly higher than plasma antioxidant capacity of smoking elderly subjects. The concentration of TBARS in young non-smoking volunteers was lower than that in young smokers. The concentration of TBARS in elderly non-smoking volunteers was lower than in elderly smokers. Plasma concentrations of alpha-tocopherol, beta-carotene and ascorbic acid were significantly lower in elderly smoker than in elderly non-smokers of the same age. No difference in the plasma levels of alpha-tocopherol, beta-carotene and ascorbic acid were found in 22-year-old smoking and non-smoking subjects. In vitro addition of ascorbic acid, uric acid, or Trolox to plasma samples significantly increased their total antioxidant capacity. Decrease of FRAP values and increase of TBARS concentrations is a significant physiologic condition of the aging process. Supplementation of antioxidants could be useful for the enhancement of antioxidant screen in plasma.
EN
Plasma potassium increases with exercise intensity. Subjects (n=8) were monitored for changes in plasma potassium while exercising at progressively increasing steady-state intensities and for two hours of recovery. Plasma potassium was significantly increased at 100% of VO2peak compared to 20% and 40% (p<0.01). Plasma potassium at 60 and 120 minutes of recovery from exercise was significantly higher than 6 minutes post exercise (p<0.015). These results support the supposition that high-intensity exercise may lead to hyperkalemia, and also indicates that increases in [K+] occur up to two hours after the cessation of exercise, a newly reported phenomenon. Although, high levels of plasma potassium are known to cause cardiac abnormalities and related events, exercise induced changes in normal healthy adults are not currently believed to have clinical implications
EN
Gliding discharge plasma in a large scale reactor was used for decomposition of tetrachloromethane. The new power supply system based on a power inverter was used. The conversion of CCl4 was investigated in air at normal pressure. The reactor was made of a quartz-glass tube 60 mm in diameter and contained three converging electrodes 140 mm long. Effects of the initial CCl4 concentration, gas flow rate and discharge power on CCl4 conversion have been studied. The conversion of CCl4 was high in all cases reaching a maximum of 90%. The conversion of tetrachloromethane decreased with increasing initial concentration of CCl4 in the reaction mixture. Changing the gas flow rate from 1000 Nl h-1 to 1400 Nl h-1 decreased the conversion of tetrachloromethane.
6
Content available remote

Plasma recycling of chloroorganic wastes

100%
EN
A high temperature of thermal plasma provides more efficient decomposition of the wastes in comparison to traditional combustion. Due to the high temperature and high density of energy in the plasma, the destruction rate is high, which determines a high efficiency waste decomposition. The main products of pyrolysis plasma chloroorganic compounds are pyrolysis gas and pyrolysis coke. In order to reduce carbon soot, the steam supported reaction was used. Application of plasma at a temperature range from 1000 to 1750 K enabled destruction of the chloroorganic compounds with a very good yield. Several degradation products were received , which were analyzed. In the research electric arc plasma was used in the process of pyrolysis chloroorganic waste utilization. The reactor with a rotating arc was applied. Selected chloroorganic compounds were selected as the model: chloromethane (CH3Cl), carbon tetrachloride (CCl4), chlorobenzene (C6H5Cl) and dichlorobiphenyl (PCB-C12H8Cl2). Based on the amount of the individual components, chloroorganic in the exhaust gases, and the amount introduced to the plasma decomposition, percentage yield was calculated. Research results indicated that decomposition efficiency was more than 99,8% with the exception of CCl4 pyrolysis, which in the exhaust had a content of 0.2% CCl4.
Open Physics
|
2003
|
vol. 1
|
issue 4
708-756
EN
An investigation was made of the characteristics of the formation of a selfcontroled volume discharge for the pumping of CO2 lasers, i.e. self-sustained volume discharge (SSVD), which involved a preliminary filling of a discharge gap by an electron flux from an auxiliary-discharge plasma. We have found that this method was suitable for large interelectrode gaps, that distortion of the electric field in the gap by the space charge of the electron flux played an important role in the formation of the discharge and that the electrodes could be profiled dynamically during propagation of an electron flux through the discharge gap and a SSVD could form in systems with a strongly inhomogeneous field. High power SSVD based CO2 laser systems have been created and investigated. Another type of self-controled volume discharge without pre-ionization, i.e. a selfinitiated volume discharge (SIVD), in nonchain HF lasers with SF6−C2H6 mixtures was investigated as well in our review. We have established that, after the primary local electrical breakdown of the discharge gap, the SIVD spreads along the gap in directions perpendicular to that of the electric field by means of the successive formation of overlapping diffuse channels under a discharge voltage close to its quasi-steady state value. It is shown that, as new channels appear, the current flowing through the channels formed earlier decreases. The volume occupied by the SIVD increases with increase in the energy deposited in the plasma and, when the discharge volume is confined by a dielectric surface, the discharge voltage increases simultaneously with increase in the current. The possible mechanisms which explain the observed phenomena, namely the dissociation of SF6 molecules and electron attachment SF6 molecules, are examined. A simple analytical model, which makes it possible to describe these mechanisms at a qualitative level, was developed. High power SIVD based HF(DF) lasers have been developed and tested.
EN
The redox status of plasma thiols can be a diagnostic indicator of different pathological states. The aim of this study was to identify the age dependent changes in the plasma levels of total, free and protein bound glutathione, cysteine and homocysteine. The determination was conducted in plasma of three groups of rats: 1) young (3-month-old), 2) middle aged (19-month-old), and 3) old (31-month-old). Total levels of glutathione, cysteine and homocysteine and their respective free and protein-bound fractions decreased with age. The only exception was a rise in free homocysteine concentration in the middle group, which indicates a different pattern of transformations of this thiol in plasma. The drop in the level of protein-bound thiols suggests that the antioxidant capacity of plasma diminishes with age, which, consequently, leads to impaired protection of -SH groups through irreversible oxidation. The plasma sulfane sulfur level also declines with age, which means that aging is accompanied by inhibition of anaerobic sulfur metabolism.
Open Chemistry
|
2005
|
vol. 3
|
issue 3
377-386
EN
A plasma induced degradation process has been studied to treat 4-nitrotoluene (4-NT) present as an aqueous pollutant. The plasma was locally generated from a glow discharge around a tip of a platinum anode in an electrolytic solution. The influence of initial pH and Fe2+ on the degradation was examined. Major intermediates resulting from the degradation process were identified. Amongst the aromatic intermediates, p-hydroxybenzoic acid was the predominant degradation product. The formation of oxalic acid, malic acid was also observed. The final products of degradation were NH4+, NO3− and CO2. Based on the analysis of intermediates and the kinetic considerations, the degradation was shown to follow a pseudo-first order reaction hence, a possible reaction pathway was proposed.
EN
Polyethylene terephthalate (PET) foils have been exposed to oxygen plasma and its afterglow in order to reveal compositional and structural modifications of the surface layer. Oxygen plasma was created by electrode-less RF discharge in a glass chamber so the O-atom density was close to 1022 m-3 although the density of charged particles was only about 1 × 1016 m-3. Long-living reactive particles created in plasma were leaked into the afterglow chamber using a two-stage rotary pump of pumping speed 4.4 × 10-3 m3 s-1. The density of O-atoms in the afterglow as measured with a catalytic probe was 3 × 1021 m-3, while the density of reactive oxygen molecules was estimated theoretically. The functionalization was accomplished even after a brief exposure to either plasma or afterglow since all samples were saturated with oxygen-rich functional groups as revealed by XPS. The water contact angle measurements, however, showed that only plasma treatment allowed for super-hydrophilicity, explained by rich surface morphology as detected by AFM. The differences in morphological properties between plasma and afterglow treated samples were explained by different interaction mechanisms between low and high energy particles impinging the polymer surface.
EN
A 6-carboxycellulose (in medicine known as “oxidized cellulose” or “oxycellulose”) is one of the cellulose derivatives popular in the field of surgery. Health products based on oxidized cellulose are great local hemostatics with unique bactericidal and fully bioabsorbable effects. Traditional process of native cellulose oxidation is described as a complex radical reaction in strong acidic liquid medium doped by toxic nitrous radicals (NO*). Our plasma-chemical reaction demonstrates a new synthesis method of oxidized cellulose with unique bactericidal effect. This plasma-chemical treatment is based on atmospheric plasma discharge in liquid medium leading to the oxidation of polysaccharide molecules resulting in oxycellulose. Final oxycellulose properties were evaluated by infrared spectroscopy and carboxyl content determination. The biological impact showed a strong germicidal effect.
EN
The decomposition of CCl4 in air was investigated at atmospheric pressure in two discharges. Reactors used to generate electrical discharges were powered by the same electric power supply. In both reactors, nearly 90% conversion of CCl4 was obtained. All chlorine was in the form of Cl2 in the process carried out in the barrier discharge, while in the spark discharge, COCl2 was formed. The conversion of CCl4 to COCl2 ranged from 2 to 12%. NO was formed in both discharges but the NO content in the gas leaving the reactors was 1.7–2.7% for the spark discharge and 0.045–0.06% for the barrier discharge. O3 was produced only in the barrier discharge and its content ranged from 0.1 to 0.2%.
EN
Background: Numerous authors have shown that selenium (Se) concentration and glutathione peroxidase (GSH-Px) activity in plasma of chronic kidney disease (CKD) patients are lower than in healthy subjects, but there are only few publications on the level of GSH-Px protein in those patients and no reports on the effect of Se supplementation to HD patients on the level of this enzyme. Subjects and Methods: Se concentration and GSH-Px protein level in plasma were measured in a group of 30 CKD patients on hemodialysis (HD) supplemented with 200 µg Se/day for 3 months, and 28 patients on HD administered with placebo. Se concentration was measured by graphite furnace atomic absorption spectrometry and plasma GSH-Px protein level by the sandwich ELISA method using polyclonal antibody specific for human plasma GSH-Px. Results: Se concentration in patients on placebo did not change throughout the 3-month study period, but increased significantly in Se supplemented group. Se supplementation to CKD patients on HD had no effect on the level of GSH-Px protein. Conclusions: The lack of GSH-Px protein in CKD patients on HD is not linked to Se deficiency since the level of this element increased after Se supplementation while enzyme protein level did not change. The damaged kidney of HD patients is unable to synthesize GSH-Px, even after induction with selenium.
14
Content available remote

Important problems of future thermonuclear reactors*

88%
Nukleonika
|
2015
|
vol. 60
|
issue 2
331-338
EN
This paper concerns important and difficult problems connected with a design and construction of thermonuclear reactors, which have to use nuclear fusion reactions of heavy isotopes of hydrogen, i.e., deuterium (D) and tritium (T). There are described conditions in which such reactions can occur, and different methods of a high-temperature plasma generation, i.e., high-current electrical discharges, intense microwave pulses, and injection of energetic neutral atoms (NBI). There are also presented experimental facilities which can contain hot plasma for an appropriate period, and particularly so-called tokamaks. The second part presents the technical problems which must be solved in order to build a thermonuclear reactor, that might be used for energetic purposes. There are considered problems connected with a choice of constructional materials for a vacuum chamber, its internal parts, external windings generating a magnetic field, and necessary shields. The next part considers the handling of radioactive tritium; the using of alpha particles (4He) for additional heating of plasma; recuperation of hydrogen isotopes absorbed in the tokamak internal parts, and a removal of a helium excess. There is presented a scheme of a future thermonuclear power plant and critical comments on a road map which should enable the construction of an industrial thermonuclear reactor (DEMO).
EN
The metabolism of oxygen in aerobic organisms leads to generation of reactive oxygen species (ROS). These entities are able to oxidize almost all classes of macromolecules, including proteins, lipids and nucleic acids. The physiological level of ROS is usually regulated by antioxidant defense mechanisms. There are at least three groups of antioxidant enzymes: superoxide dismutases, catalases and glutathione peroxidases (GSH-Pxs) which neutralize ROS. The trace elements (copper, zinc and selenium) bound to the active sites of the above listed enzymes play an important role in the antioxidant defense system. In mammals, a major function of selenium (Se) and Se-dependent GSH-Pxs is to protect cells from oxidative stress. Selenium concentrations and GSH-Px activities are altered in blood components of chronic kidney disease (CKD) patients. The Se level is frequently lower than in healthy subjects and the concentration very often decreases gradually with advancing stage of the disease. Studies on red cell GSH-Px activity in CKD patients reported its values significantly lower, significantly higher and lower or higher, but not significantly as compared with healthy subjects. On the other hand, all authors who studied plasma GSH-Px activity have shown significantly lower values than in healthy subjects. The degree of the reduction decreases gradually with the progression of the disease. High inverse correlations were seen between plasma GSH-Px activity and creatinine level. A gradual decrease in plasma GSH-Px activity in CKD patients is due to the fact that this enzyme is synthesized predominantly in the kidney and thus the impairment of this organ is the cause of the enzyme's lower activity. Se supplementation to CKD patients has a slightly positive effect in the incipient stage of the disease, but usually no effect was observed in end-stage CKD. Presently, kidney transplantation is the only treatment that may restore plasma Se level and GSH-Px activity in patients suffering from end-stage CKD. A few studies have shown that in kidney recipients, plasma Se concentration and GSH-Px activity are restored to normal values within a period of 2 weeks to 3 months following surgery and thus it can be acknowledged that Se supplementation to those patients has a positive effect on plasma GSH-Px activity.
Open Physics
|
2003
|
vol. 1
|
issue 1
145-152
EN
The neutrino-electron scattering in a dense degenerate magnetized plasma under the conditions μ 2 > 2eB ≫ μE is investigated. The volume density of the neutrino energy and momentum losses due to this process are calculated. The results we have obtained demonstrate that plasma in the presence of an external magnetic field is more transparent for neutrino than for non-magnetized plasma. It is shown that neutrino scattering under conditions considered does not lead to the neutrino force acting on plasma.
EN
MicroRNAs (miRNAs) are small non-coding, single-stranded RNAs (19–25 nucleotides long) that regulate expression of multiple target genes, predominantly by binding to the 3′ untranslated region of messenger RNA (mRNA) transcripts, resulting either in translational inhibition or mRNA degradation. miRNAs are found in many bodily fluids, including plasma and serum, and are protected from degradation in the circulation through association with lipids, proteins, or microparticles, making them attractive disease biomarker candidates. Circulating levels of cardiac miRNAs (including miR-1, miR-133a, miR-208a, miR-208b, and miR-499) have been frequently reported as elevated in both coronary heart disease (CHD) and heart failure (HF) and have been proposed as candidate biomarkers that reflect the severity of myocardial injury. Subsequent large, array-based screening studies comparing patients and controls have identified altered expression of additional miRNAs, not just those of cardiac origin. However, among these studies there has been little consensus as to which miRNAs are top candidates for diagnosis or prognosis in either CHD or HF. The measurement of circulating miRNAs is further complicated by the timing of collection, especially after acute cardiac events while miRNA levels in blood may be rapidly changing; confounding influences from medications or contaminating blood cells at the time of sampling; and the need for standardization of normalization strategies. This review evaluates recent developments in the identification of circulating miRNAs as markers for diagnosis and prognosis in CHD and HF, and the methodological issues in measurement of circulating miRNAs.
EN
introduction: The recommended biological material for the parathyroid hormone (PTH) assay is venous blood plasma. According to diagnostic kit manufacturers, the PTH concentration can also be determined in blood serum. The aim of the study was to determine whether differences exist between PTH measured in serum and in plasma. Material and methods: The study was conducted on venous blood samples (plasma and serum) obtained from 92 patients at the Clinic of Endocrinology, University Hospital WAM – CSW. The PTH concentration was measured with an Immulite 1000 analyzer (Siemens), and iPTH kit. Results: The PTH values in plasma and serum were the same only in 3 cases. In 46 samples (50%), a higher hormone level was observed in the plasma, and in 43 cases (47%), a higher concentration was obtained in serum. The absolute differences between the PTH values in the tested biological materials ranged from 0 to 38 pg/mL, and increased together with the hormone concentration. The relative differences (percentage ratio of absolute differences to plasma PTH concentration) ranged from 0 to 34.3%. However, neither the absolute nor the relative differences were statistically significant (p > 0.05). The classification of PTH concentrations according to the reference values for each biological material (i.e. normal, reduced or elevated) was found to be concordant in 83 tested samples (90%). Conclusion: The identified PTH concentrations in the plasma and serum were not identical but comparable and in most cases the differences did not affect the clinical interpretation of the results.
PL
WSTĘP: Materiałem biologicznym zalecanym do oznaczania parathormonu (parathyroid hormone – PTH) jest osocze krwi żylnej pobranej na wersenian sodowo-potasowy, jednak według producentów zestawów diagnostycznych do pomiaru PTH można stosować zarówno osocze, jak i surowicę krwi. Celem pracy było zbadanie, czy wartości PTH oznaczane w surowicy i w osoczu krwi żylnej są porównywalne. MATERIAŁ I METODY: W badaniu wykorzystano próbki krwi żylnej (osocze i surowica) uzyskane od 92 pacjentów Poradni Endokrynologicznej Uniwersyteckiego Szpitala Klinicznego im. Wojskowej Akademii Medycznej – Centralnego Szpitala Weteranów (USK im. WAM – CSW) w Łodzi. Oznaczenia hormonu wykonano na analizatorze Immulite 1000 (Siemens) zestawem iPTH. WYNIKI: Wartości PTH oznaczone w osoczu i w surowicy były jednakowe tylko w 3 przypadkach. W 46 próbkach (50%) wyższe wartości hormonu odnotowano w osoczu, a w 43 przypadkach (47%) w surowicy. Różnice bezwzględne między wartościami PTH w badanych materiałach wahały się od 0 do 38 pg/mL i zwiększały się wraz ze wzrostem stężenia hormonu. Różnice względne (procentowy stosunek różnic bezwzględnych do stężenia PTH w osoczu) wynosiły od 0 do 34,3%. Jednak zarówno różnice bezwzględne, jak i względne nie były znamienne statystycznie (p > 0,05). Po klasyfikacji stężeń – na prawidłowe, obniżone lub podwyższone – na podstawie wartości referencyjnych PTH dla danego materiału biologicznego uzyskano zgodność wyników w 83 badanych próbkach (90%). WNIOSKI: Stężenia PTH oznaczane w osoczu i w surowicy nie są identyczne, ale porównywalne, a różnice w większości przypadków nie wpływają na interpretację kliniczną wyników.
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