HBr Concentrations Research Articles

Neural Substrates for Hand and Shoulder Movement in Healthy Adults: A Functional near Infrared Spectroscopy Study

Characterization of cortical activation patterns during movements in healthy adults may help our understanding of how the injured brain works. Upper limb motor tasks are commonly used to assess impaired motor function and to predict recovery in individuals with neurological disorders such as stroke. This study aimed to explore cortical activation patterns associated with movements of the hand and shoulder using functional near-infrared spectroscopy (fNIRS) and to demonstrate the potential of this technology to distinguish cerebral activation between distal and proximal movements. Twenty healthy, right-handed participants were recruited. Two 10-s motor tasks (right-hand opening-closing and right shoulder abduction-adduction) were performed in a sitting position at a rate of 0.5 Hz in a block paradigm. We measured the variations in oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) concentrations. fNIRS was performed with a 24-channel system (Brite 24®; Artinis) that covered most motor control brain regions bilaterally. Activation was mostly contralateral for both hand and shoulder movements. Activation was more lateral for hand movements and more medial for shoulder movements, as predicted by the classical homunculus representation. Both HbO2 and HbR concentrations varied with the activity. Our results showed that fNIRS can distinguish patterns of cortical activity in upper limb movements under ecological conditions. These results suggest that fNIRS can be used to measure spontaneous motor recovery and rehabilitation-induced recovery after brain injury. The trial was restropectively registered on January 20, 2023: NCT05691777 (clinicaltrial.gov).

Bromine speciation in volcanic plumes: new in situ derivatization LC-MS method for the determination of gaseous hydrogen bromide by gas diffusion denuder sampling

Abstract. The chemical characterization of volcanic gas emissions gives insights into the interior of volcanoes. Bromine species have been correlated with changes in the activity of a volcano. In order to exploit the volcanic bromine gases, we need to understand what happens to them after they are outgassed into the atmosphere. This study aims to shed light on the conversion of bromospecies after degassing. The method presented here allows for the specific analysis of gaseous hydrogen bromide (HBr) in volcanic environments. HBr is immobilized by reaction with 5,6-epoxy-5,6-dihydro-[1,10]-phenanthroline (EP), which acts as an inner coating inside of diffusion denuder tubes (in situ derivatization). The derivative is analyzed by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS). The collection efficiency for HBr (99.5 %), the collection efficiency for HBr alongside HCl (98.1 %), and the relative standard deviation of comparable samples (8 %) have been investigated. The comparison of the new denuder-based method and Raschig tubes as alkaline traps resulted on average in a relative bias between both methods of 10 ± 6 %. The denuder sampling setup was applied in the plume of Masaya (Nicaragua) in 2016. HBr concentrations in the range between 0.44 and 1.97 ppb were measured with limits of detection and quantification below 0.1 and 0.3 ppb respectively. The relative contribution of HBr as a fraction of total bromine decreased from 75 ± 11 % at the Santiago crater (214 m distance to the volcanic emission source) to 36 ± 8 % on the Nindiri rim (740 m distance). A comparison between our data and the previously calculated HBr, based on the CAABA/MECCA box model, showed a slightly higher trend for the HBr fraction on average than expected from the model. Data gained from this new method can further refine model runs in the future.

Cortical Effects of Noisy Galvanic Vestibular Stimulation Using Functional Near-Infrared Spectroscopy.

Noisy galvanic vestibular stimulation (nGVS) can improve different motor, sensory, and cognitive behaviors. However, it is unclear how this stimulation affects brain activity to facilitate these improvements. Functional near-infrared spectroscopy (fNIRS) is inexpensive, portable, and less prone to motion artifacts than other neuroimaging technology. Thus, fNIRS has the potential to provide insight into how nGVS affects cortical activity during a variety of natural behaviors. Here we sought to: (1) determine if fNIRS can detect cortical changes in oxygenated (HbO) and deoxygenated (HbR) hemoglobin with application of subthreshold nGVS, and (2) determine how subthreshold nGVS affects this fNIRS-derived hemodynamic response. A total of twelve healthy participants received nGVS and sham stimulation during a seated, resting-state paradigm. To determine whether nGVS altered activity in select cortical regions of interest (BA40, BA39), we compared differences between nGVS and sham HbO and HbR concentrations. We found a greater HbR response during nGVS compared to sham stimulation in left BA40, a region previously associated with vestibular processing, and with all left hemisphere channels combined (p < 0.05). We did not detect differences in HbO responses for any region during nGVS (p > 0.05). Our results suggest that fNIRS may be suitable for understanding the cortical effects of nGVS.

Hydrogen bromide in syngas: Effects on tar reforming, water gas-shift activities and sintering of Ni-based catalysts

Hydrogen bromide is an emerging impurity of syngas formed during gasification of electronic and municipal solid waste. The influence of HBr on catalytic activity and deactivation of various Ni-based tar reforming catalysts was investigated. The data demonstrate the detrimental effect on catalytic properties (1) occurs at HBr concentrations above 500 ppmv, (2) is more severe compared to HCl and (3) varies greatly with the catalyst structure. The characterization of spent catalysts revealed that the formation of chemisorbed Ni-Br species, enhanced Ni sintering and depletion of NiO-Al2O3 sites could be the reasons for the loss of tar reforming and water-gas shift activities. On the other hand, no significant effect of HBr on catalyst coking was observed. The comparison of different catalysts demonstrated that the negative HBr impact can be successfully mitigated by developing a nanostructured catalyst with high porosity and Ni dispersion that ensure the strong Ni-support interaction.

Co-pyrolysis of polyethylene with products from thermal decomposition of brominated flame retardants

Co-pyrolysis of brominated flame retardants (BFRs) with polymeric materials prevails in scenarios pertinent to thermal recycling of bromine-laden objects; most notably the non-metallic fraction in e-waste. Hydro-dehalogenation of aromatic compounds in a hydrogen-donating medium constitutes a key step in refining pyrolysis oil of BFRs. Chemical reactions underpinning this process are poorly understood. Herein, we utilize accurate density functional theory (DFT) calculations to report thermo-kinetic parameters for the reaction of solid polyethylene, PE, (as a surrogate model for aliphatic polymers) with prime products sourced from thermal decomposition of BFRs, namely, HBr, bromophenols; benzene, and phenyl radical. Facile abstraction of an ethylenic H by Br atoms is expected to contribute to the formation of abundant HBr concentrations in practical systems. Likewise, a relatively low energy barrier for aromatic Br atom abstraction from a 2-bromophenol molecule by an alkyl radical site, concurs with the reported noticeable hydro-debromination capacity of PE. Pathways entailing a PE-induced bromination of a phenoxy radical should be hindered in view of high energy barrier for a Br transfer into the para position of the phenoxy radical. Adsorption of a phenoxy radical onto a Cu(Br) site substituted at the PE chain affords the commonly discussed PBDD/Fs precursor of a surface-bounded bromophenolate adduct. Such scenario arises due to the heterogeneous integration of metals into the bromine-rich carbon matrix in primitive recycling of e-waste and their open burning.

161 Brain Activation Assessed with Functional Near-Infrared Spectroscopy (FNIRS) During Stepping and Gait in Older People and Those with PD

Abstract Background and Aim Past research has shown that compared with healthy peers, people with Parkinson’s Disease (PD) generate poorer stepping responses and display reduced ability to adapt gait to unexpected targets and obstacles. However, the neural basis of these impairments in PD is unclear. Here, we aimed to investigate cortical activation in pre-frontal and motor areas using functional near-infrared spectroscopy (fNIRS) during stepping and gait adaptability in people with PD, compared with healthy adults. Methods Forty-four people with PD (&amp;gt;40 years, Hoen &amp; Yahr stage 1-3) and 44 healthy age and sex-matched healthy adults performed three cognitively-demanding stepping tasks and a test of gait adaptability. We recorded relative changes in oxy-haemoglobin (HbO) and deoxy-haemoglobin (HbR) concentrations in the dorsolateral prefrontal cortex, supplementary motor area, premotor cortex and primary cortex using fNIRS. Results Data collection is ongoing with &amp;gt;75% participants already assessed. We will conduct between group-comparisons to compare HbO and HbR concentrations in the selected regions of interest in the stepping and the gait adaptability tests. Physical and cognitive predictors of brain activation in each task in each group will also be computed using regression models. Conclusion Based on the results of our recent systematic review of fNIRS-recorded brain activation during walking tasks (1), we hypothesise that compared with healthy-aged matched peers, people with PD will show increased prefrontal and motor cortices activation during stepping and gait adaptability tests. This would suggest that people with PD require more attentional resources for safe walking. Reference (1) Pelicioni et al. Prefrontal cortical activation measured by fNIRS during walking: effects of age, disease and secondary task. Peer J 2019; 7: e6833.

Functional Near infrared spectroscopy (fNIRS) to investigate language patterns development over ages

Event Abstract Back to Event Functional Near infrared spectroscopy (fNIRS) to investigate language patterns development over ages Julie Tremblay1*, Anne Gallagher1, Berta González-Frankenberger1, 2, Natacha Paquette1, 3, Phetsamone Vannasing1, Olivia Florea1, 3, Renée Béland4, Franco Lepore1, 5 and Maryse Lassonde1, 3 1 Ste-Justine Hospital Research Center, Canada 2 Universidad Nacional Autónoma de México, Mexico 3 University of Montréal, Psychology, Canada 4 University of Montréal, Orthophony, Canada 5 University of Montréal, Canada Neuroimaging techniques such as fMRI have been the object of many studies aiming to localise language areas and find a replacement for the amobarbital procedure. Although good results have been obtained in adults, fMRI is not always conclusive in children, mainly because fMRI scanner is a stressful environment for young children and it is difficult to verify if they perform the task correctly. Functional near infrared spectroscopy (fNIRS) seems to be a good alternative to investigate language, especially in paediatric populations. We recorded fNIRS data during a verbal fluency task performed aloud by 41 individuals. Participants were divided in 4 groups: 1 - younger children (3-6 years (n=10)), 2- older children (7-10 years (n=10)), adolescents (11-16 years (n=12)) and adults (18 years + (n=9)). A method to detect and correct abrupt variations due to movement artefact developed by our group has been applied on individual data. Then, modified Beer Lambert Law was applied to estimate variations in HbO2 and HbR concentrations. For all groups an increase in HbO2 concentration was seen during the language task in Broca's area along with a weaker activation in the homologous area. The effect of age on hemodynamic response was further assessed using a mixed design ANOVA with Hemisphere as a within-subject factor and age groups as the between-subject factor. Results revealed a significant main effects for factors Group (F(3, 37) = 5.42, p < 0.05) indicating an increase of amplitude with age and a main effect for hemisphere (F(1, 37) = 35.63, p < 0.001) indicating a higher HbO2 concentration in the left hemisphere than in the right hemisphere in all groups. fNIRS is a good technique to investigate language dominance in participants from as young as 3 years old. Finally, our results suggest that our movement artefact rejection and correction tool increases significantly the NIRS data quality especially in young participants. Keywords: Language, Children, Broca's area, fNIRS, verbal fluency Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Oral Presentation Topic: Language Citation: Tremblay J, Gallagher A, González-Frankenberger B, Paquette N, Vannasing P, Florea O, Béland R, Lepore F and Lassonde M (2015). Functional Near infrared spectroscopy (fNIRS) to investigate language patterns development over ages. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00078 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Mrs. Julie Tremblay, Ste-Justine Hospital Research Center, Montréal, Canada, julie.tremblay3@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Julie Tremblay Anne Gallagher Berta González-Frankenberger Natacha Paquette Phetsamone Vannasing Olivia Florea Renée Béland Franco Lepore Maryse Lassonde Google Julie Tremblay Anne Gallagher Berta González-Frankenberger Natacha Paquette Phetsamone Vannasing Olivia Florea Renée Béland Franco Lepore Maryse Lassonde Google Scholar Julie Tremblay Anne Gallagher Berta González-Frankenberger Natacha Paquette Phetsamone Vannasing Olivia Florea Renée Béland Franco Lepore Maryse Lassonde PubMed Julie Tremblay Anne Gallagher Berta González-Frankenberger Natacha Paquette Phetsamone Vannasing Olivia Florea Renée Béland Franco Lepore Maryse Lassonde Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Studies on Spatial, Spectral, and Energy Characteristics of Copper-HBr Laser Radiations

This paper presents, for the first time, a study on the pulse-to-pulse variation in the spatial, spectral, and energy characteristics (pointing instability, divergence, intensity, as well as the emission line-width and their fluctuations) of both green and yellow radiations of a copper-HBr laser (Cu-HBrL). The experimental study was performed in a high power (specific power: 70 W/L, total power: 72 W), 18 kHz repetition rate Cu-HBrL for different wall plug electrical input powers (6-9.5 kW) and HBr concentrations (5%-9%). These observations are supplemented with studies on near field spatial intensity and temporal profiles under all working conditions. It is observed that the characteristics are widely different for the two radiation components. The experimental observations are supported by comprehensive analysis in terms of input power coupling, laser gain and its radial distribution, thermally induced wave-front aberrations, optical noise contribution, and laser kinetics.

Changes in water structure induced by the guanidinium cation and implications for protein denaturation.

The effect of the guanidinium cation on the hydrogen bonding strength of water was analyzed using temperature-excursion Fourier transform infrared spectra of the OH stretching vibration in 5% H 2O/95% D 2O solutions containing a range of different guanidine-HCl and guanidine-HBr concentrations. Our findings indicate that the guanidinium cation causes the water H-bonds in solution to become more linear than those found in bulk water, and that it also inhibits the response of the H-bond network to increased temperature. Quantum chemical calculations also reveal that guanidinium affects both the charge distribution on water molecules directly H-bonded to it as well as the OH stretch frequency of H-bonds in which that water molecule is the donor. The implications of our findings to hydrophobic solvation and protein denaturation are discussed.

The Influence of Cortical Maturation on the BOLD Response: An fMRI Study of Visual Cortex in Children

We performed blood oxygenation level-dependent (BOLD) functional MR imaging in 11 children younger than 5 y of age and 10 children older than 5 y of age. All but five of the children in the older age group were tested under light anesthesia. We examined the cerebral oxidative metabolism (CMRO(2)) associated with the processing of a flashed and a reversing checkerboard stimulus. These stimuli had been shown in a previous study to induce identical vascular responses. The reversing checkerboard activated twice the neuronal population of the flashed checkerboard, doubling the CMRO(2) associated with it. We compared the extent of activation for the positive BOLD response and found that it did not differ between the different age groups. We estimated the oxidative metabolism by examining the change in the local deoxyhemoglobin (HbR) concentration using Delta R2*. Because both stimuli induced the same vascular response, any increase in oxygen requirement would have to be met by the identical blood volume. Increasing CMRO(2) will therefore result in an increase in the oxygen extraction fraction (OEF), which raises the local HbR concentration. In the younger children, both checkerboard stimuli produced identical, high HbR concentrations. In the older children, the HbR concentration to the flashed stimulus was significantly lower than to the reversing stimulus. We conclude that, for identical stimuli, the oxidative energy requirement associated with the cortical processing is higher in young children than in older children because the presence of superfluous synaptic connections in the immature visual system activates a larger neuronal population.

Diffuse optical imaging of brain activation: approaches to optimizing image sensitivity, resolution, and accuracy

Near-infrared spectroscopy (NIRS) and diffuse optical imaging (DOI) are finding widespread application in the study of human brain activation, motivating further application-specific development of the technology. NIRS and DOI offer the potential to quantify changes in deoxyhemoglobin (HbR) and total hemoglobin (HbT) concentration, thus enabling distinction of oxygen consumption and blood flow changes during brain activation. While the techniques implemented presently provide important results for cognition and the neurosciences through their relative measures of HbR and HbT concentrations, there is much to be done to improve sensitivity, accuracy, and resolution. In this paper, we review the advances currently being made and issues to consider for improving optical image quality. These include the optimal selection of wavelengths to minimize random and systematic error propagation in the calculation of the hemoglobin concentrations, the filtering of systemic physiological signal clutter to improve sensitivity to the hemodynamic response to brain activation, the implementation of overlapping measurements to improve image spatial resolution and uniformity, and the utilization of spatial prior information from structural and functional MRI to reduce DOI partial volume error and improve image quantitative accuracy.

HBr concentration and temperature measurements in a plasma etch reactor using diode laser absorption spectroscopy

In situ measurements of HBr concentrations and rotational temperatures were recorded in a 300 mm planar inductively coupled plasma (ICP) etch reactor using diode laser wavelength modulation spectroscopy. A pair of diode lasers operating near 1.95 and 2.00 μm were wavelength tuned over the R(7) and P(2) transitions of HBr (2–0 band), time-division multiplexed, and directed through an industrial wafer etch reactor. The rotational temperature (typically 435±8 K) was determined from the ratio of peak absorption signals and the HBr concentration was determined from the measured temperature and absorbance from a single line. The measured rotational temperature in the plasma was relatively independent of conditions studied. The estimated HBr dissociation fraction ranged from 25%–60%, depending on the ICP power applied, gas flow rate, and chamber pressure. Decreases in HBr concentration were detected 1 cm above the wafer surface during blank silicon wafer etching. The HBr dissociation fractions were measured before and after SF6 plasma clean with various focus rings made of quartz, alumina, and silicon carbide. The HBr dissociation fraction increased 17% with the quartz focus ring after the chamber was seasoned. The silicon carbide focus ring had essentially no influence on HBr concentration before and after chamber clean. The success of this work demonstrates the potential of diode lasers for in situ monitoring of the plasma etch process for real time control applications.

Cerebral oxygenation state in childhood moyamoya disease: a near-infrared spectroscopy study

Near-infrared spectroscopy was used to measure the relative concentration changes of oxygenated hemoglobin (HbO 2), deoxygenated hemoglobin (HbR), and total hemoglobin (t-Hb) before, during, and after hyperventilation in eight patients with childhood moyamoya disease who underwent surgery. The patients were divided into the following two groups: those with and those without re–build-up phenomenon on electroencephalography. All patients except one exhibited decreased concentrations of HbO 2 and t-Hb during hyperventilation and decreased concentrations of HbO 2 and increased concentrations of HbR after hyperventilation. The difference between the hemoglobin concentration during and after hyperventilation was significantly greater in the group with the re–build-up phenomenon than the group without it ( P <0.03, Mann-Whitney U test). The patients with the re–build-up phenomenon had lower HbO 2 and higher HbR concentrations after hyperventilation. The concentrations of HbO 2 and HbR reflect an alteration in the oxygenated blood supply and/or oxygen use. Thus, it is strongly suggested that regional cerebral hypoxia and metabolic oxygen disturbances play an important role in the occurrence of the re–build-up phenomenon. Near-infrared spectroscopy is a useful noninvasive method to evaluate the efficacy of surgical treatment in childhood moyamoya disease.

The heterogeneous reaction of N2O5 with HBr on Ice comparison with N2O5+HCl

AbstractThe heterogeneous reactions of N2O5 with HCl and HBr on ice have been studied in the temperature range 180 to 200 K using a Knudsen flow reactor.The uptake of N2O5 on ice in the presence of HBr was found to be strongly dependent on the HBr concentration. For the highest HBr concentrations used a maximum uptake coefficient of N2O5 of γ=0.11 has been determined. We observed Br2 and HONO in 80% yield as products with respect to N2O5 taken up. The uptake coefficient of N2O5 on ice in the presence of HCl was found to be 3.2·10−2 and increased with increasing HCl concentration. CINO2 was detected as the sole reaction product with a maximum yield of 63% with respect to N2O5 consumed.Hydrolysis of N2O5 resulting in HNO3 was found to be competitive with the title reaction. For the case of the HBr reaction the branching ratio between Br2 and HONO formation, on the one hand, and hydrolysis of N2O5, on the other hand, has been determined. Mechanistic aspects of the heterogeneous reaction of N2O5 with HX have been discussed.

Evidence for HBr production due to minor channel branching at mid‐latitudes

Recently, Nolt et al. [1997] have presented HBr measurements over the height range 20–36 km. We have compared model calculations with these measurements and find definitive evidence for non‐zero branching ratios for HBr production from either HO2+BrO, k1b, or OH+BrO, k2b. For k1b, best agreement between modelled and observed HBr concentrations is obtained if the branching ratio increases from ∼0.4% at 20 km, to about 2% at 34 km with no additional contribution from the OH+BrO branch. However, a height‐independent value of 1% also produces reasonable results. This branching ratio contradicts the study of Mellouki et al. [1994]. For OH+BrO, the best value of k2b appears to be 2–3%, if k1a = 0 which is comparable to the recently determined branching ratio for HCl production from the analogous chlorine reaction, OH+ClO.

γ-Radiolyse von 4-Nitrophenol in Wässriger HBr-Lösung

In the γ-radiolysis of aqueous solutions of 4-nitrophenol, 4-nitropyrocatechol ( G= 2·95) and 4-aminophenol ( G = 1·1) are formed. The addition of HBr in concentrations up to 0·5 mol dm −3 HBr has a protective effect. The G-value for the disappearance of 4-nitrophenol is strongly reduced (Fig. 2). At 0·5 mol dm −3 HBr G(4-nitro-pyrocatechol) is lowered to 0·1, and G(4-aminophenol) to 0·15. This effect is explained by assuming that the OH radicals react with Br − giving Br . atoms which further react to Br 2 −. An explanation of this protective effect is based on the assumption that Br . or Br 2 − may either dehydrogenate the 4-nitrophenol-H atom adduct, or that, alternatively, the 4-nitrophenol-Br atom adduct may react with the H atom adduct resulting in the formation of HBr and two molecules of 4-nitrophenol. With HBr concentrations above 0·5 mol dm −3 the G value for the disappearance of the substrate increases again owing to loss through bromination. In a 9 mol dm −3 HBr solution 2-bromo-4-nitrophenol ( G = 4,9) and 4-aminophenol ( G = 1·37) are formed. Some possible mechanisms of bromination are discussed. A satisfactory material balance was obtained for all HBr concentrations investigated.

Rapid Solvent Extraction of Indium(III) and Its Separation from Gallium(III) and Aluminum(III)

Abstract Mesityl oxide (4-methyl-3-pentene-2-one) has been used extensively for the solvent extraction separation of several transition elements (l). In the present communication, solvent extraction behavior of indium (III) toward mesityl oxide as a function of HCl or HBr concentrations has been studied and a simple and rapid method for the solvent extraction separation of gallium, indium, and aluminum has been proposed.

Nature of Isomeric-Transition-Induced Bromine-82 Reactions with CH4 and CD4

The role of excess kinetic energy and thermal processes in the 82Br reaction in gaseous CH4 and CD4 activated by 82mBr isomeric transition (IT) was determined using rare-gas and bromine additives. Possible isotope effects were investigated between (n, γ-induced 80Br and 80mBr and between CH4 and CD4 target molecules. The “freeze–thaw” technique and (n, γ) “in-reactor” technique were employed in determining the 82Br organic yields. The effects of He, Kr, Xe, and Br2 additives on the reaction of CH4 and CD4 with 82Br activated by the (IT) process are presented. The data appear to extrapolate, at zero mole fraction CH4, to 3.7% ± 0.5% for the He, Kr, and Xe additives and to 0% for Br2. This would indicate that 7.4% minus 3.7% is formed via excess kinetic-energy processes and that 3.7% of the organic 82Br is formed via thermal (kinetic-energy-independent) processes, probably involving Br+ ions in their first two excited states, P13 and P03. The data suggest the absence of a target molecule isotope effect between CH4 and CD4 in the 82Br(IT)-activated process, but does suggest a target molecule isotope effect for (n, γ-activated bromine reactions. The data for bromine reactions involving excess kinetic energy were analyzed using the kinetic theory of hot reactions. The reactivity integral values I were found to be very low. The kinetic theory showed good internal consistency for (IT)-activated bromine reactions. Experimental data showed the absence of any isotope effect between (n, γ)-induced 80mBr and 80Br reaction in CH4. The use of HBr as a source molecule was reinvestigated in the CD4 system and found to give organic yields higher than those of Br2 systems at low mole fractions. This difference diminished at higher HBr concentrations.

Ion-exchange procedures : IX. Cation exchange in HBr solutions

Results of a systematic study of the cation exchange behavior of elements in HBr solutions are given for a Dowex 50 resin. Many elements show adsorption minima at moderate HBr concentrations folowed by a rapid increase in adsorbability at high HBr concentrations. Marked differences in adsorbabilities of the elements occur, particularly in dilute and concentrated HBr solutions. Implications of the data for separations are discussed and typical separations illustrated.