Humic substances, which are randomly cross-linked heterogeneous organic materials of high molecular weight, comprise a major fraction of the organic matter in soils and sediments. Because humic ...substances have a variety of functional groups, they play a major role in controlling the physical and chemical characteristics of natural waters, soils, and sediments. Sedimentary humic substances are considered to be the precursors of petroleum-forming kerogens. Sulfur is thought to play a major role in forming humic substances in anoxic marine sediments. Because of their structural heterogeneity, humic substances are not easily amenable to biochemical degradation and, thus, are generally considered to be biologically refractory. The complexity and heterogeneity of humic substances render the elucidation of their chemical structure a major analytical challenge. Degradative techniques, such as pyrolysis GC−MS, can change a sample's structure during preparation and analysis and, thus, may give inaccurate information. In this study, we investigated the sulfur-containing functional groups in humic acids from various marine sediments using XANES spectroscopy which has proved to be an important, nondestructive tool for analyzing sulfur forms. Humic acids were isolated from near-surface sediments from three locations: a salt marsh in Shelter Island, NY; the Peru Margin; and Florida Bay. We found that organic sulfides, di- and polysulfides, sulfonates, and organic sulfates are the major forms of sulfur in these sedimentary humics. The reduced-sulfur structures, organic sulfides, and di- and polysulfides, are essentially intramolecular as opposed to the highly oxidized forms of sulfur, sulfonates, and ester-bonded sulfates, which can only be present as end groups. The abundance of the reduced-sulfur structures reflects the extent to which sulfur is involved in forming intramolecular cross-links which are crucial for building up the macromolecular structures of humic substances. The significance of the presence of the different sulfur functionalities in humic substances is discussed in relation to early diagenesis and preservation of organic matter in marine sediments.
It is known that nitric oxide (NO) influences the activities of glycolytic enzymes, resulting in alteration of glycolysis rate. We investigated the effect of NO donors on the energy metabolism of rat ...erythrocytes. Rat erythrocyterich blood suspensions were aerobically incubated for 2 hours (1) as controls or (2) with different concentrations of NO donors: nitroglycerin (NTG), isosorbide dinitrate (ISDN), molsidomine (MO), and sodium nitroprusside (SNP). NTG, ISDN, MO, and SNP significantly (p < 0.05) increased glucose consumption and lactate accumulation in rat erythrocytes in a dose-dependent manner, indicating stimulation of glycolysis. The increased rate of glycolysis was accompanied by elevation of energy production (p < 0.05), but no changes in ATP levels were observed. The dose-dependent increase of glycolytic ATP production and the unaltered levels of ATP resulted in considerably shortened ATP-turnover time with the maximal experimental doses of NO donors used, indicating the stimulation of the ATP-consuming process in rat erythrocytes. The metabolic effects of NTG, ISDN, MO, and SNP were not mimicked by exogenous 8-Br-cGMP, NaNO2, or NaNO3, suggesting that the NO donor-induced stimulation of glycolysis and abbreviation of ATP-turnover time in rat erythrocytes was mediated by NO as an effector molecule, irrespective of the irreversible scavenger effect of hemoglobin. The implications of the NO effect on energy metabolism of erythrocytes is discussed.
The elevated luteinizing hormone (LH) and androgen concentrations characteristic of women with polycystic ovaries (PCO) are considered crucial factors in their infertility. The somatostatin analogue ...octreotide lowers LH and androgen concentrations in women with PCO. The effects of octreotide given concurrently with human menopausal gonadotrophin (HMG) were therefore compared with that of HMG alone in 28 infertile women with PCO resistant to clomiphene. In 56 cycles of combined HMG and octreotide therapy there was more orderly follicular growth compared with the multiple follicular development observed in 29 cycles in which HMG was given alone (mean number of follicles > 15 mm diameter on the day of human chorionic gonadotrophin (HCG) administration: 2.5 +/- 0.2 and 3.6 +/- 0.4 respectively; P = 0.026). There was a significantly reduced number of cycles abandoned (> 4 follicles > 15 mm diameter on day of HCG) in patients treated with octreotide+HMG, so that HCG had to be withheld in only 5.4% of cycles compared to 24.1% with HMG alone (P < 0.05). The incidence of hyperstimulation was also lower on combined treatment. Octreotide therapy resulted in a more 'appropriate' hormonal milieu at the time of HCG injection, with lower LH, oestradiol, androstenedione and insulin concentrations. Although growth hormone concentration was similar on both regimens, significantly higher insulin growth factor-I concentrations were observed on the day of HCG in women on combined therapy than on HMG alone.
Summary form only given. In the last few decades, there has been a huge advance in atmospheric pressure plasma research; many plasma devices have been constructed and analyzed using various ...diagnostic techniques. One of the promising devices is atmospheric pressure plasma jet operating in the plasma bullet mode with applied frequencies varying from 5 to 120 kHz and applied voltages can be in sinusoidal or pulsed 1, 2. Several authors report that the plasma jet that is formed is not continuous.
Detection of muons at 150 GeV/ c with a CMS Preshower prototype Barney, D.; Bialas, W.; Kokkas, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2006, Letnik:
564, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The analysis of 150
GeV/
c muon data collected during a test of a CMS Preshower prototype is presented. The test took place in 2004 in the H4 beam at CERN. The muon signal extraction is possible ...after pedestal subtraction and common mode correction. The results of a Geant-4-based simulation, developed for the Preshower prototype test, are also presented. The results of the simulation are found to be in excellent agreement with the data. It is also demonstrated that by combining the results of the data analysis and simulation an absolute calibration of the CMS Preshower detector system can be performed.
Natural antimony targets were irradiated in a 60 MeV bremsstrahlung beam and gamma spectrometric measurements were performed. The goal was to establish the yield of
Sn, a radionuclide with great ...potential for application in medicine. Considering that
Sn is predominantly produced through a photonuclear reaction in which an charged particle is emitted (
Sb(γ,p3n)), the yield of this tin isotope is much lower than the yields of several antimony isotopes produced in (γ,xn) reactions. It has been estimated that photonuclear reactions on natural antimony could produce
Sn activities needed for therapeutic applications, with accelerators having electron currents of the order of mA. For the used bremsstrahlung energy of 60 MeV, it was estimated how much
Sn activity can be expected when exposing the antimony target.
The SPD (Spin Physics Detector) is a planned spin physics experiment in the second interaction point of the NICA collider that is under construction at JINR. The main goal of the experiment is the ...test of basic of the QCD via the study of the polarized structure of the nucleon and spin-related phenomena in the collision of longitudinally and transversely polarized protons and deuterons at the center-of-mass energy up to 27 GeV and luminosity up to \(10^{32}\) 1/(cm\(^2\) s). The data rate at the maximum design luminosity is expected to reach 0.2 Tbit/s. Current approaches to SPD computing and offline software will be presented. The plan of the computing and software R&D in the scope of the SPD TDR preparation will be discussed.
The effects of the sodium nitroprusside (SNP), a nitric oxide (NO) donor clinically used in the treatment of hypertensive emergencies on the energy production of rat reticulocytes were investigated. ...Rat reticulocyte-rich red blood cell suspensions were aerobically incubated without (control) or in the presence of different concentrations of SNP (0.1, 0.25, 0.5, 1.0 mM). SNP decreased total and coupled, but increased uncoupled oxygen consumption. This was accompanied by the stimulation of glycolysis, as measured by increased glucose consumption and lactate accumulation. Levels of all glycolytic intermediates indicate stimulation of hexokinase-phosphofructo kinase (HK-PFK), glyceraldehyde 3-phosphate dehydrogenase (GAPD) and pyruvate kinase (PK) activities in the presence of SNP. Due to the decrease of coupled oxygen consumption in the presence of SNP, ATP production via oxidative phosphorylation was significantly diminished. Simultaneous increase of glycolytic ATP production was not enough to provide constant ATP production. In addition, SNP significantly decreased ATP level, which was accompanied with increased ADP and AMP levels. However, the level of total adenine nucleotides was significantly lower, which was the consequence of increased catabolism of adenine nucleotides (increased hypoxanthine level). ATP/ADP ratio and adenylate energy charge level were significantly decreased. In conclusion, SNP induced inhibition of oxidative phosphorylation, stimulation of glycolysis, but depletion of total energy production in rat reticulocytes. These alterations were accompanied with instability of energy status.
Nitric oxide (NO) in many cells inactivates aconitase and mitochondrial respiratory chain, and influenced glyceraldehyde 3-phosphate dehydrogenase activity. The aim of this study was to evaluate role ...of nitroglycerin (NTG), a widely used NO donor, on energy metabolism of rat reticulocytes. Rat reticulocyte rich red blood cell suspensions containing 70-100% of reticulocytes, were aerobically incubated without (control) or in the presence of different concentrations of (a) NTG (0.1, 0.25, 0.5, 1.0, 1.5 mmol/l), (b) 8-Br-cGMP (0.1, 0.5, 1.0 mmol/l) and (c) NaNO2 and NaNO3 (1 mmol/l). NTG in dose- and time-dependent manner decreased total (p>0.05; EC50 = 0.78+/-0.05 mmol/l) and coupled (p<0.05; EC50 = 0.50+/-0.04 mmol/l) and increased uncoupled oxygen consumption (p<0.05: EC50 = 0.36+/-0.01 mmol/l). They were accompanied by stimulation of glycolysis, as measured by increased glucose consumption and lactate accumulation (p<0.001 EC50 = 0.53 and 0.53 mmol/l, respectively). Levels of all glycolytic intermediates in the presence of NTG indicate stimulation of HK-PFK, GA3PDH and PK activity. NTG significantly decreased ATP level, which accompanied by increased ADP and AMP levels. However, level of total adenine nucleotides (TAN) was significantly lower, which was consequence of increased catabolism of adenine nucleotides (increased hypoxanthine level; p<0.05). Stimulation of glycolysis accompanied with inhibition of the OxP, activation of HK-PFK, decrease of ATP and simultaneous rise of ADP and AMP levels, all together represent an example of Pasteur effect occurring in NTG-treated reticulocytes. In rat reticulocytes under steady state conditions 93% of overall energy was produced by OxP, but only 7% by glycolysis. Due to decrease of coupled oxygen consumption in the presence of NTG, ATP production via OxP was significantly diminished. Simultaneous increase of glycolytic ATP production is not enough to provide constant either ATP production or concentration. Calculated mean ATP-turnover time was prolonged even for 45% in the presence of 1.5 mmol/l NTG. Metabolic effects of NTG were not mimic by exogenous 8-Br-cGMP, NaNO2 or NaNO3, which indicate that NTG induced a) inhibition of coupled respiration and b) stimulation of glycolysis in rat reticulocytes are mediated by NO as an effector molecule.
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