Concentration Of HBr Research Articles

Optimization of the CuBr＋Ne＋HBr brightness amplifier operating mode for high-speed imaging

The paper presents the research and development of a low-volume brightness amplifier for imaging laser active optical systems (laser monitors) with a pulse repetition frequency (PRF) of up to 100 kHz. A small-sized active element and pumping source based on tasitron have been developed. The effect of the brightness amplifier’s operating features (concentration of CuBr and HBr) on the numerical characteristics of images obtained in the laser monitor has been studied. The optimal concentrations were determined, and it was proven for the first time that they should be 30% lower than what is needed for obtaining maximum laser power. It was shown that increasing the CuBr concentration leads to a decrease in the field of view. The effect of the one-pass amplification profile on the quality of LOAS-based images was experimentally determined. A small-sized active element (40 cm3) excited with a specific pulse energy input of 238 μJ/cm3 can be used to obtain images with a time resolution of up to 10 μs.

Abstract TP81: Time-Domain Near-Infrared Spectroscopy in Acute Ischemic Stroke Patients

Background: cerebral microcirculation might reveal important prognostic information for acute ischemic stroke. Time-Domain Near-Infrared Spectroscopy (TD-NIRS) is an advanced optical technique that estimates quantitatively and non-invasively the oxygenation in microcirculation of cerebral outer layers at the bedside of the patient. We aimed to measure hemoglobin species and tissue oxygen saturation in acute ischemic stroke patients comparing them to controls according to brain areas and large vessel recanalization status. Methods: TD-NIRS measurements within 24 h of stroke onset (1 st time point) and after 24 h (2 nd time point) were performed on anterior circulation stroke patients classified as lacunar and recanalized or non-recanalized partial/total anterior circulation syndrome. Fiducial markers categorized the brain region below each TD-NIRS probe as ischemic or non-stroke areas. We evaluated the concentration of deoxyhemoglobin (HbR), oxyhemoglobin (HbO), total hemoglobin (HbT) and tissue oxygen saturation (StO 2 ) and assessed differences compared to control subjects and according to large vessel occlusion. Results: TD-NIRS measurements were performed on 47 acute ischemic stroke patients. At 1 st time point the ischemic area had higher HbR and HbT compared to controls in both recanalized (p=8.2·10 -4 ; p=0.03) and non-recanalized patients (p=4.9·10 -3 , p=0.03), but lower StO 2 only in recanalized patients (p=0.015). The ischemic area of recanalized patients had higher concentration of HbR, HbO, HbT compared to the ipsilateral non-stroke area (p=0.01; p=3.6·10 -3 ; p=2.0·10 -3 ). The same pattern was observed at 2 nd time point. Recanalized patients had lower mean StO 2 in the ipsilateral hemisphere compared to non-recanalized patients at both time points (p=0.016, p=0.011). Conclusions: TD-NIRS can be performed during routine Stroke Unit activity and it is able to detect significant differences in hemoglobin species in large vessels ischemic stroke patients compared to controls. Data suggest that StO 2 could serve as surrogate functional marker of the metabolic activity of the rescued brain tissue.

Optical Properties and Molar Hemoglobin Concentration of Skeletal Muscles Measured <italic>In Vivo</italic> With Wearable Near Infrared Spectroscopy

Near-infrared spectroscopy (NIRS) is a widely-used noninvasive optical technique for measuring concentration of hemoglobin species in human tissues. Despite its potential, NIRS has seen limited clinical application largely due to a lack of in-vivo standard reference. Hence, cross-validation studies to validate novel NIRS instrumentation against established NIRS devices are needed. This in-vivo study compared a wearable continuous-wave (CW-NIRS) oximeter against a non-wearable frequency-domain (FD-NIRS) oximeter on optical properties and hemoglobin concentrations. To measure absolute coefficients and stoichiometric hemoglobin concentrations, the CW-NIRS oximeter exploits spectral properties of water. Both CW-NIRS and FD-NIRS provided physiologically-valid measurements in skeletal muscles during normoxia, hypoxia, and hyperemia. Although absorption-scattering crosstalk was evident, absorption coefficient $\mu _{a}$ and reduced scattering coefficient $\mu '_{s}$ at 690nm and deoxyhemoglobin concentration (HbR) were mostly within agreement limits, and the measurements differed principally by a systematic offset. Specifically, CW-NIRS estimated larger $\mu '_{s}$ values (+2 cm−1) and smaller $\mu _{a}$ (from −0.04 to −0.08 cm−1) at all wavelengths. The results suggest that lower-cost, wearable CW-NIRS oximeters are a potential alternative to FD-NIRS to measure optical properties and molar concentration of oxyhemoglobin and HbR in skeletal muscles in-vivo as long as the estimated water content is reasonably accurate.

(Solid + Liquid) Phase Equilibria for the Systems CsBr + EuBr3 + H2O and CsBr + EuBr3 + HBr (∼12.3%) + H2O at 298.15 K and Atmospheric Pressure and Thermodynamic and Fluorescent Properties of the New Solid-Phase Compound

In this study, the (solid + liquid) phase equilibria for the two systems of CsBr + EuBr3 + H2O and CsBr + EuBr3 + HBr (∼12.3%) + H2O at 298.15 K and atmospheric pressure were determined by isothermal solubility method. Schreinemaker wet residue approach was used to determin the solid phases obtained from the studied systems. The related phase diagrams were depicted based upon the experimental data. There were two invariant points, three invariant curves, and three crystallization fields corresponding to CsBr, 5CsBr·2EuBr3·20H2O, and EuBr3·6H2O in the two phase diagrams. New double salt 5CsBr·2EuBr3·20H2O was incongruently soluble in the two systems. The content of EuBr3 in two invariant points decreased as the concentration of HBr in equilibrium liquid phase increased, while that of CsBr changed a little. The new solid-phase compound 5CsBr·2EuBr3·20H2O was investigated using chemical, XRD, and TG-DTG analyses. Additionally, the standard molar enthalpy of solution for 5CsBr·2EuBr3·20H2O in water was confir...

Copper bromide vapor brightness amplifiers with 100 kHz pulse repetition frequency

The paper presents a laser monitor with 10μs time-resolution based on a high-frequency copper bromide vapor brightness amplifier. A sync circuit has been designed for single-pulse imaging. The analysis of amplifying characteristics of the active elements and active optical system (laser monitor) parameters allowed to determine the optimal concentration of HBr at which the images can be obtained with minimum distortions. For the active element operating at high frequencies (more than 50kHz) as a brightness amplifier, the concentration of HBr must be lower than that needed for obtaining the maximum output power. The limiting brightness temperature of the background radiation which does not affect the image quality is determined. The potential feasibility of using a proposed brightness amplifier for visualizing processes blocked from viewing by the background radiation with the brightness temperature up to 8000K is demonstrated.

Caffeine differentially alters cortical hemodynamic activity during working memory: a near infrared spectroscopy study.

BackgroundCaffeine is a widely used stimulant with potentially beneficial effects on cognition as well as vasoconstrictive properties. In functional magnetic imaging research, caffeine has gained attention as a potential enhancer of the blood oxygenation level-dependent (BOLD) response. In order to clarify changes of oxy- and deoxyhemoglobin (HbO and HbR) induced by caffeine during a cognitive task, we investigated a working memory (WM) paradigm (visual 2-back) using near-infrared spectroscopy (NIRS).ResultsBehaviorally, caffeine had no effect on the WM performance but influenced reaction times in the 0-back condition. NIRS data demonstrate caffeine-dependent alterations of the course of the hemodynamic response. The intake of 200 mg caffeine caused a significant decrease of the HbO response between 20 and 40 s after the onset of a 2-back task in the bilateral inferior frontal cortex (IFC). In parallel, the HbR response of the left IFC was significantly increased due to caffeine intake.ConclusionsIn line with previous results, we did not detect an effect of caffeine on most aspects of behavior. Effects of caffeine on brain vasculature were detected as general reduction of HbO. Neuronal effects of caffeine are reflected in an increased concentration of HbR in the left hemisphere when performing a verbal memory task and suggest influences on metabolism.

Solid + Liquid Equilibria for the Systems CsBr + ErBr3 + H2O and CsBr + ErBr3 + HBr (∼12.3%) + H2O at 298.15 K and Atmospheric Pressure and Thermodynamic and Fluorescent Properties of the New Solid-Phase Compound

The phase equilibria of the ternary system CsBr + ErBr3 + H2O and the quaternary system CsBr + ErBr3 + HBr (∼12.3 %) + H2O at 298.15 K were determined experimentally with the isothermal solubility method. Based on the measured solubility data, the corresponding phase diagrams were plotted. In the ternary system, three crystallization regions corresponding to CsBr, 3CsBr·2ErBr3·16H2O, and ErBr3·9H2O were found. Similarly, there were three crystallization regions corresponding to CsBr, 3CsBr·2ErBr3·16H2O, and ErBr3·7H2O in the quaternary system. The phase diagrams of the ternary and quaternary systems were compared, and it showed that (1) a new double salt 3CsBr·2ErBr3·16H2O was formed which was incongruently soluble in the two systems; (2) the area of the crystallization region of 3CsBr·2ErBr3·16H2O increased with the increasing concentration of HBr in the equilibrium liquid phase, and (3) ErBr3·9H2O transformed into ErBr3·7H2O when the HBr reached a certain amount. The new solid-phase compound 3CsBr·2ErBr3·16H2O was characterized by chemical analysis, XRD, and TG-DTG techniques. The standard molar enthalpy of solution of 3CsBr·2ErBr3·16H2O in water was confirmed to be −(6.69 ± 0.29) kJ·mol–1 by microcalorimetry in the limit of infinite dilution and its standard molar enthalpy of formation was determined to be −(7846.1 ± 1.2) kJ·mol–1. The fluorescence excitation and emission spectra of 3CsBr·2ErBr3·16H2O were measured. The results indicated that up-conversion spectra of the new solid phase compound exhibit at 470 nm and are excited at 710 nm.

Revisiting the Mechanism of β-O-4 Bond Cleavage During Acidolysis of Lignin. Part 6: A Review

ABSTRACTThis paper reviews our results on the acidolysis of dimeric non-phenolic β-O-4-type lignin model compounds in aqueous 82% 1,4-dioxane containing an acid at 85°C. It was shown that the mechanism of a C6-C2-type model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol IX, is fairly different from that of a C6-C3 analogue, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol XX, suggesting the significance of the presence of the γ-hydroxymethyl group. It was confirmed that the hydride transfer mechanism exists as a reaction route of the benzyl-cation-type intermediates derived from both compounds, and the contribution of this mechanism is greater than expected in the acidolysis of compound XX. An enol ether compound, 2-(2-methoxyphenoxy)-3-(3,4-dimethoxyphenyl)prop-2-en-1-ol, was first detected in the acidolysis of compound XX using the DBr/D2O/1,4-dioxane system. It was confirmed in the acidolysis of compound XX using HBr that the mechanism is different from that in the system using either HCl or H2SO4 and an unknown mechanism contributes to the reaction. This unknown mechanism surprisingly contributed more with decreasing concentration of HBr or Br−, provided that Br− still existed in the system.

Brassinosteroid-mediated enrichment in yield attributes, active constituents and essential oil production in Mentha arvensis L.

Recently, brassinosteroids (BRs) have emerged as a new group of growth promoting phytohormones. 28-homobrassinolide (HBR) is one of the several brassinosteroids, the role of which in enhancing growth, productivity and quality of plants, via improving various physiological processes, has been established both under stress and normal conditions. Out of a large number of essential oil bearing plants, mint (Mentha arvensis L.) constitutes the most important source of therapeutic agents used in the alternative systems of medicine. The mint plant has marvelous medicinal and aromatic values. In view of enhancing yield and quality of this medicinally important plant, a pot experiment was conducted under natural conditions of net house. The study was aimed at exploring the effect of four concentrations of HBR (10−0, 10−8, 10−7 and 10−6 M) on the performance of mint with regard to physiological attributes, herbage yield, content and yield of essential oil, and active constituents at 100 and 120 days after planting. The foliar application of HBR enhanced physiological attributes, herbage yield and the yield and content of most of the active constituents (menthol, L-methone, isomenthone and menthyl acetate) of mint at both the stages, with 10−7 M concentration proving the best. However, the next higher concentration of HBR (10−6 M) exhibited no further increase in the values of the attributes studied. Rather, 10−6 M was slightly inferior to 10−7 M concentration; but it always proved significantly better than the control.

Bifunctional redox flow battery: 2. V(III)/V(II)– l-cystine(O 2) system

A new bifunctional redox flow battery (BRFB) system, V(III)/V(II)— l-cystine(O 2), was systematically investigated by using different separators. It is shown that during charge, water transfer is significantly restricted with increasing the concentration of HBr when the Nafion 115 cation exchange membrane is employed. The same result can be obtained when the gas diffusion layer (GDL) hot-pressed separator is used. The organic electro-synthesis is directly correlated with the crossover of vanadium. When employing the anion exchange membrane, the electro-synthesis efficiency is over 96% due to a minimal crossover of vanadium. When the GDL hot-pressed separator is applied, the crossover of vanadium and water transfer are noticeably prevented and the electro-synthesis efficiency of over 99% is obtained. Those impurities such as vanadium ions and bromine can be eliminated through the purification of organic electro-synthesized products. The purified product is identified to be l-cysteic acid by IR spectrum. The BRFB shows a favorable discharge performance at a current density of 20 mA cm −2. Best discharge performance is achieved by using the GDL hot-pressed separator. The coulombic efficiency of 87% and energy efficiency of about 58% can be obtained. The cause of major energy losses is mainly associated with the cross-contamination of anodic and cathodic active electrolytes.

Oxidative dissolution of cobalt oxalate and manganese oxalate in acetic acid solutions

The oxidative dissolution of cobalt oxalate and manganese oxalate in acetic acid solutions with a flow of oxygen–nitrogen mixing gas at pressure of 1.5 MPa was studied. Experiments investigating the following parameters: the stirring speed, the reaction temperature, the concentration of oxygen containing gas, the concentration of hydrobromic acid and leaching time, showed that cobalt oxalate and manganese oxalate can be dissolved completely in acetic acid solutions at the best conditions. It was found that the dissolution rate increased with increasing reaction temperature, and with decreasing concentration of HBr. It was observed that the presence of oxygen was necessary to reaction occur, but a concentration of O 2 beyond about 3% has almost no effect on the dissolution rate. It was determined that the first-order pseudo-homogenous reaction model can describe the dissolution rate of cobalt oxalate and manganese oxalate during the leaching. The data obtained for the oxidative dissolution of oxalates indicated that the process is controlled by the dissolution rate of oxalate salts into acetic acid solutions.

How much luxury is there in 'luxury perfusion'? An analysis of the BOLD response in the visual areas V1 and V2.

We re-analyzed the functional magnetic resonance imaging data from a study involving awake, adult, human volunteers in order to examine the influence of vascular density on the blood oxygenation level-dependent (BOLD) response. We employed a flashed and reversing stimulus paradigm where the latter stimulated twice the number of receptive fields and with it doubled the neuronal metabolic load (CMRO2) compared to the former stimulus. The blood flow increase to these stimuli was identical, so that differences in the BOLD response are due to differences in the oxygen extraction fraction. By comparing the BOLD response in human striate cortex (V1) and its neighbor, extra-striate area V2 to the two stimuli, we were able to determine the influence of the higher vascular density of striate cortex on the BOLD response. In striate cortex, the extent of activation, as measured by the number of activated voxels, was larger for the flashed than for the reversing stimulus. In extra-striate area V2, no such difference in the extent of activation was noted. Gauging the local concentration of HbR using deltaR2*, we found it to be significantly lower for the flashed than for the reversing checkerboard. We estimated the HbR concentration in extra-striate area V2 to be double that of striate cortex independent of the stimulus presented. A frequency distribution of the deltaR2* values for the flashed and reversing checkerboard revealed a shift consistent with an increase in the HbR concentration between areas V1 and V2. The metabolically most demanding stimulus, the reversing checkerboard was associated with the highest HbR concentration and with the largest number of voxels with a negative BOLD response.

Nitrate reductase activity and yield of Lens culinaris sprayed with 28-homobrassinolide

Thirty-day-old plants ofLens culinaris(L.) Medic. cv. Pusa-6 were sprayed with 10-10, 10-8or 10-6M aqueous solutions of 28-homobrassinolide (HBR). Root length and nodule number per plant decreased, whereas the leaf nitrate reductase activity (E.C. 1.6.6.1) at 60, 90 and 120 days after sowing and the seed yield at harvest increased significantly in plants sprayed with either concentration of HBR. The values increased at first with an increase in the concentration of HBR but decreased with a further increase above 10-8M, which proved best for improving seed production.

Kinetics of the formation of symmetrical wax esters from the corresponding alcohols with the use of hydrobromic acid and hydrogen peroxide

AbstractThe primary aliphatic alcohols n‐octanol, n‐decanol, and n‐dodecanol have been converted to their corresponding symmetrical esters by using HBr and H2O2 in the absence of a solvent. The reaction was carried out at 30, 40, and 50°C and at mole ratios of alcohol to HBr of 1∶0.1, 1∶0.2, 1∶0.3, and 1∶0.5. The rate of the reaction was found to increase with increase in the reaction temperature and concentration of HBr. The maximal conversion of n‐octanol was 72% at 40°C and a mole ratio of n‐octanol to HBr of 1∶0.5. The kinetics of the reaction have been established, and the reaction was found to be first‐order with respect to alcohol and bromine concentration in the organic phase, and second‐order with respect to both. The second‐order rate constants for n‐octanol, n‐decanol, and n‐dodecanol are 27.08, 32.58, and 37.42 mL mol−1 min−1, respectively, at 40°C. The activation energy for the esterification reaction of n‐octanol was found to be 16.32 kcal mol−1.

Photosynthetic Rate, Growth, and Yield of Mustard Plants Sprayed with 28-Homobrassinolide

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10−10, 10−8, or 10−6 M aqueous solution of 28-homobrassinolide (HBR). The HBR-treated plants were healthier than those treated with water and yielded more. Maximum increase over control was found in 60-d-old, 10−8 M-HBR-treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C. 4.2.1.1) activity, and net photosynthetic rate (PN), at harvest in number of pods per plant and seed yield per plant (the respective values were 25, 30, 34, 69, 24, and 29 %). A further increase in the concentration of HBR (10−6 M) did not make any additional impact on the growth and yield. Increased CA activity and PN were correlated with growth and seed yield.

Ozone depletion potential of CH3Br

The ozone depletion potential (ODP) of methyl bromide (CH3Br) can be determined by combining the model‐calculated bromine efficiency factor (BEF) for CH3Br and its atmospheric lifetime. This paper examines how changes in several key kinetic data affect BEF. The key reactions highlighted in this study include the reaction of BrO + HO2, the absorption cross section of HOBr, the absorption cross section and the photolysis products of BrONO2, and the heterogeneous conversion of BrONO2 to HOBr and HNO3 on aerosol particles. By combining the calculated BEF with the latest estimate of 0.7 year for the atmospheric lifetime of CH3Br, the likely value of ODP for CH3Br is 0.39. The model‐calculated concentration of HBr (∼0.3 pptv) in the lower stratosphere is substantially smaller than the reported measured value of about 1 pptv. Recent publications suggested models can reproduce the measured value if one assumes a yield for HBr from the reaction of BrO + OH or from the reaction of BrO + HO2. Although the DeMore et al. [1997] evaluation concluded any substantial yield of HBr from BrO + HO2 is unlikely, for completeness, we calculate the effects of these assumed yields on BEF for CH3Br. Our calculations show that the effects are minimal: practically no impact for an assumed 1.3% yield of HBr from BrO + OH and 10% smaller for an assumed 0.6% yield from BrO + HO2.

Study on the gas phase HBr-catalyzed reaction between UF 6 and SiH 4 at room temperature

The gas phase HBr-catalyzed reaction UF 6 + SiH 4 at room temperature and its kinetic mechanism were investigated. It was found that this catalyzed reaction followed the first-order kinetics, and the reaction rate constant was proportional to the concentration of catalyst HBr, e.g. the measured rate constants were 0.75 × 10 −3, 1.58 × 10 −3 and 3.00 × 10 −3s −1 at the respective concentrations of HBr at 0.5 × 133.3, 1.0 × 133.3 and 2.0 × 133.3Pa. The proposed kinetic mechanism of the HBr-catalyzed reaction was in good accordance with the measured results.

Effects of 28-homobrassinolide on yields of wheat, rice, groundnut, mustard, potato and cotton

Yield responses of some economically important crop plants due to foliar applications of low concentrations of 28-homobrassinolide (HBR) were studied in experiments conducted at research stations and in farmers' fields in India during 1989–95. Foliar sprays of different concentrations of HBR were applied at tillering and spike/panicle initiation in wheat (0·5 and 1·0 mg/l) and rice (0·25, 0·50 and 1·00 mg/l); at flowering and pegging in groundnut (0·25 and 0·50 mg/l); 30 and 45 days after sowing (DAS) in mustard (0·25 and 0·50 mg/l); 25 and 35 days after emergence in potato (0·25 and 0·50 mg/l); and 30, 50, 70 DAS in cotton (0·1 and 1·0 mg/l). The HBR treatments significantly (P<0·05 and P<0·01) increased grain yields in wheat, rice and mustard, pod yields in groundnut, tuber yields in potato and seed cotton yields, over control. The extent of yield improvement due to HBR was influenced by crop species, concentration of HBR, plant growth stage at application and frequency of application.

Solubility of HBr in sulfuric acid at stratospheric temperatures

The solubility of HBr in 54 to 72 wt % sulfuric acid at low temperatures (200 to 240 K) was measured using two different experimental techniques. In the first, the time dependence of the uptake coefficient of HBr was measured in a Knudsen cell reactor and analyzed to give the effective Henry's law coefficient. In the second, equilibrium vapor pressures of HBr (gas) over solutions containing known concentrations of HBr (dissolved) were measured. The two techniques were in good agreement Typical values of the effective Henry's law coefficient at 220 K were 1.5×107 M/atm for 54 wt %, 2.2 × 106 M/atm for 60 wt %, 1.5×105 M/atm for 66 wt %, and 8.5×103 M/atm for 72 wt % sulfuric acid. The measured solubilities combined with the stratospheric gas phase concentration of HBr indicate that very little HBr will be dissolved in stratospheric sulfate aerosol particles.

Cu単結晶 (111) 面の溶解に及ぼす丸川液中の溶解抑制剤臭化水素酸濃度の影響

The dissolution at screw dislocation sites and dislocation-free sites of the Cu (111) surface was studied as a function of concentration of HBr in Marukawa’s etchant (FeCl3·6H2O-HCl-HBr). Etching was carried out for 10 s at 280 K, and the dissolved quantities along lateral and longitudinal directions at dislocation, H and D, and the dissolved thickness of the matrix surface, S, were determined from measurement of size of dislocation etch pits and the step height at the boundary between the masked surface and the etched surface, respectively. An increase of the concentration of HBr in the etchant caused a decrease in H and an increase in D, but it produced no change in S. The role of inhibitor HBr was discussed on the basis of the spiral theory of crystal dissolution at screw dislocation and the two-dimensional nucleation theory at dislocation-free surface.