Proton Resonance Spectroscopy Research Articles

Evaluation of adsorption behaviour of benzylidene chitosan derivatives at mild steel/ 0.5 M H2SO4 solution interface

Four green benzylidene chitosan derivatives (BCs) were synthesized and evaluated as anti-corrosive substances for the first time against mild steel corrosion in 0.5 M H2SO4 solution. The synthesized BCs were laid to infrared spectroscopy and proton resonance spectroscopy for structural confirmation. Gravimetric and electrochemical experiments were accustomed to appraise the effectiveness of inhibitors, however, Scanning Electron Microscopy-Electron Dispersive Spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS) were exploited to evaluate the protective mechanism offered by benzylidene chitosan derivatives. Experimental results demarcate the synthesized inhibitors; Anisaldehyde modified Chitosan (CMB), 2-Hydroxy-4-methoxybenzaldehyde modified Chitosan (CHMB), 2,4-Dimethoxybenzaldehyde modified Chitosan (CDMB) and 2-Bromo-4-methoxybenzaldehyde modified Chitosan (CBMB) exhibiting praising inhibitory properties for mild steel corrosion and CDMB was seen possessed preferable inhibition potential at the finest concentration of 500 mgL-1 owing to the proximity of two electron-donating OCH3 groups. Furthermore, the inhibitors have been recorded to behave mixed type with pronounced impact on hydrogen evolution kinetics. The order of inhibition efficacy obtained was CDMB (98.8 %) > CHMB (95.4 %) > CMB (92.8 %) > CBMB (89.2 %) which was further validated by quantum chemical calculations which later opened up about the mechanistic approach involved in electron transfer from inhibitors to metallic vacant orbitals. Additionally, the effect of molecular structure possessed by synthesized inhibitors has been correlated with observed variation in their corrosion inhibition efficiency.

КОНФИГУРАЦИОННО-ИЗОМЕРНЫЙ СОСТАВ КАУЧУКОВ: ОПРЕДЕЛЕНИЕ МЕТОДОМ СПЕКТРОСКОПИИ ЯМР 1H И 13C

Nuclear magnetic resonance (NMR) spectroscopy is a convenient method for studying the structure and isomeric composition of diene rubbers. A simple and reproducible method is proposed for determining the content of both rubber and impurity compounds, which does not require additional sample preparation. Formulas for calculating the composition of industrial products and determining the initial substances are given, the applicability of the analysis method is confirmed. In the process of work, rubbers of various brands were analyzed, their configuration-isomeric composition was established. It was found that the integration ranges given in the literature earlier and the methods for processing 1H NMR spectra differ, the signals of the groups often overlap in the spectrum, which increases the calculation error. It is shown that the structure of the industrial products under study is established most accurately by carbon proton resonance spectroscopy, and the calculation based on the PMR spectra allows confirming the data obtained with sufficient accuracy.

Magnetic resonance imaging and proton spectroscopy in the Huntington disease

Magnetic resonance imaging and proton spectroscopy in the Huntington disease

Magnetic resonance imaging in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a tauopathy, presenting clinically most often with a symmetrical akinetic-rigid syndrome, postural instability, supranuclear gaze palsy and frontal dementia. In the absence of reliably validated biomarkers, the diagnosis of PSP in vivo is presently based on clinical criteria, which to date do not include supporting imaging findings, as is accepted for other neurodegenerative diseases. However, data from conventional magnetic resonance imaging (MRI) and various advanced MRI techniques including magnetic resonance volumetry, voxel-based morphometry, diffusion-weighted and diffusion-tensor imaging, magnetization transfer imaging and proton resonance spectroscopy suggest that MRI can contribute valuable information for the differential diagnosis of PSP. We review here the presently published literature concerning MRI in PSP and discuss the potential role of MRI in differentiating PSP from other parkinsonian syndromes.

Characterization of polystyrene‐b‐poly(ethylene oxide) diblock copolymer and investigation of its micellization behavior in water

AbstractThe recent studies deal with a diblock copolymer, polystyrene–poly(ethylene oxide). Infrared spectroscopy, proton resonance spectroscopy (1H‐NMR), and laser light scattering techniques have been used to characterize the polymer. It has been concluded that the sample investigated is diblock copolymer polystyrene–poly(ethylene oxide) having molecular mass 1.656 × 104 g/mol and blocks ratio 1 : 2. The micellization behavior is explored through 1H‐NMR, laser light scattering, light absorption, surface tension, and conductance and viscosity measurements. The results conclude that the critical micelles concentration of copolymer is 0.0951 g/dL at 25°C. It has been observed that the surface tension of solution decreases with the temperature and its impact is maxima in dilute concentration region. In addition, new methodologies have been introduced to get accurate critical micelles concentration and critical micelles temperature. © 2010 Wiley Periodicals, Inc., J Appl Polym Sci, 2010

Evidence for Metabolic Hypothalamo-Amygdala Dysfunction in Narcolepsy

Proton resonance spectroscopy (1H-MRS) allows noninvasive chemical tissue analysis in the living brain. As neuronal loss and gliosis have been described in narcolepsy, metabolites of primary interest are N-acetylaspartate (NAA), a marker of neuronal integrity and myo-Inositol (ml), a glial marker and second messenger involved in the regulation of intracellular calcium. One 1H-MRS study in narcolepsy found no metabolic changes in the pontomedullary junction. Another study showed a reduction in NAA/creatine-phosphocreatine (Cr) in the hypothalamus of narcolepsy patients with cataplexy. We aimed to test for metabolic changes in specific brain areas, "regions of interest," thought to be involved in emotional processing, sleep regulation and pathophysiology of narcolepsy: hypothalamus, pontomesencephalic junction and both amygdalae. We performed 1H-MRS using a 3T Philips Achieva whole body MR scanner. Single-voxel proton MR spectra were acquired and quantified with LCModel to determine metabolite concentration ratios. The participants in the study were recruited at the outpatient clinic for sleep medicine, Department of Neurology and magnetic resonance spectroscopy was performed at the MRI facility, University Hospital Zurich. 1H-MRS was performed in fourteen narcolepsy patients with cataplexy, CSF hypocretin deficiency (10/10) and HLA-DQB1*0602 positivity (14/14) and 14 age, gender and body mass index matched controls. Patients were treatment naïve or off therapy for at least 14 days before scanning. No differences were observed in the regions of interest for (total NAA)/Cr ratios. Myo-Inositol (ml)/Cr was significantly lower in the right amygdala of the patients, compared to controls (P < 0.042). Significant negative correlations only in the patients group were found between (total NAA)/Cr in hypothalamus and ml/Cr in the right amygdala (r = -0.89, P < 0.001), between ml/Cr in hypothalamus and (total NAA)/Cr in the right amygdala (r = -63, P < 0.05) and between ml/Cr in the left amygdala and total NAA)/Cr in the pontomesencephalic junction (r = -0.69, P < 0.05). Our findings suggest amygdala involvement and possible hypothalamo-amygdala dysfunction in narcolepsy.

Palladium(II) complexes of benzaldehyde and 2-hydroxybenzaldehyde-4-H/phenyl-S-ethyl/allyl-thiosemicarbazones

The thiosemicarbazone derivatives R1-C6H4-CH=N-N=(C-S-R2)-NH-R3 [R1 = H, OH; R2 = H, Ph; R3 = C2H5, C3H5] were prepared by a modified general method. The Pd(II) complexes of the thiosemicarbazone ligands LI–VI were isolated in the compositions [Pd(L)Cl2], [Pd(L)Cl] and [Pd(L)2]. The 1: 1 and 1: 2 metal complexes have non-ionic character, and the compounds were characterized by analytical data and infrared and proton resonance spectroscopy. The cis-trans and syn-anti isomers of the thiosemicarbazones were determined by means of 1H NMR, and the coordination behavior of the polydentate thiosemicarbazone ligands towards the palladium ion were discussed.

A proton magnetic spectroscopy research on hippocampus in suicide-attempted depression

Objective To investigate the metabolic features of hippocampus in suicide-attempted depression by proton resonance spectroscopy(1H-MRS). Methods 1H-MRS was performed on bilateral hippocampi in 24 suicide-attempted depressions and 24 healthy controls. The ratios of N-acetylasparte (NAA)/creatine (Cr),choline(Cho)/Cr and myoinositol (mI)/Cr were calculated, and were used as observation marker reflecting the metabolic level of NAA, Cho and mI. The differences among all maskers in bilateral hippoeampi between the suicide-attempted depression and the control were analyzed. And differences between the left hippocampus and the right among all metabolic markers and lateralization index were used to determine the asymmetry of hippocampus metabolic. Results The ratio of NAA/Cr in the left hippocampus in suicide-attempted was significantly decreased than that in the control ( P 0.05). No correlations among all metabolic markers with the course of disease, number of episodes and HAMD17 scores and drug usage was found in the suicide-attempted depression( P>0.05). Conclusion Metabolite of NAA/Cr in left hippocampus decreased and an asymmetry of bilateral hippocampi can not be seen in the suicide-attempted depression. Key words: Suicide; Depression; Hippocampus ; Magnetic resonance spectroscopy

Methodology of clinical trials in multiple sclerosis

The scope of the paper is to summarise key issues in methodology used in clinical trials on multiple sclerosis (MS) treatment and help clinicians to better understand articles reporting the results of these trials. Relapsing ratio and disability progression based on the Expanded Disability Status Scale are currently used as clinical efficacy primary outcomes, but more global measurements should be used in future such as the MS Functional Composite. For magnetic resonance imaging (MRI) outcomes, new MRI composites and indexes are already available (Z4 score, conventional MRI-derived end-points) that, together with new MRI techniques (magnetisation- transfer MRI and proton resonance spectroscopy), offer more precise neuroimaging assessments of the disease. These efficacy measurements should be presented in articles as number needed to treat, which assists the reader to calculate and compare the treatments' power and safety.

Steric factors influencing the complex formation with cucurbit[6]uril

The complex formation between cucurbit[6]uril and different diamides was studied using proton resonance spectroscopy and calorimetric titrations. The values of the stability constants and reaction enthalpies were determined using calorimetric titrations. In solution diamides obtained from the reaction of α,ω-alkyl diamines with aliphatic carbonic acids form inclusion complexes by threading. The stability of these complexes is independent of the number of methylene groups of the diamine compounds. With increasing chain length of the aliphatic carbonic acids the complex stability raises. The thermodynamic data for the reaction of cucurbit[6]uril with diamides containing branched alky-, cycloaliphatic- or aromatic carbonic acids give no evidence for the formation of inclusion complexes. However, 1H-NMR-experiments give clear evidence of the complex formation between cucurbit[6]uril and branched alkyl diamides. Surprisingly cycloaliphatic and aromatic groups act as blocker groups although the cavity size of cucurbit[6]uril is larger than the diameter of the terminating groups.

Monitoring tumour response with proton resonance spectroscopy in low-grade gliomas

Purpose: Tumour response assessment is a primary end-point in the majority of clinical trials. Accurate quantitative tumour response analysis in low-grade gliomas (LGG) is limited by the uncertainty of the true extent of tumour margins on conventional MRI. This study evaluated changes in the choline spectroscopic signal intensity as a supplementary tool to serial MRI, monitoring the anti-tumour efficacy of Temozolomide in histologically verified LGG.

Proton Spectroscopy in a Cross-Section of HIV Positive Asymptomatic Patients Receiving Immediate Compared with Deferred Zidovudine (Concorde Study)

The purpose of this study was to examine by proton spectroscopy for any difference in cerebral metabolites in patients taking part in the Concorde study (comparing the efficacy of immediate versus deferred treatment with zidovudine on asymptomatic HIV infected individuals). Forty seven HIV positive male patients [29 immediate, 18 deferred zidovudine] were examined in the last 9 months of the therapeutic trial. Magnetic resonance imaging and proton spectroscopy were performed at 1.5 Tesla using a single voxel placed in the parieto-occipital white matter. No significant difference was found in metabolite ratios comparing immediate versus deferred zidovudine (NA/NA+Cho+Cr 0.52 vs. 0.52). High quality spectra were acquired in relatively large numbers of patients and logistically spectroscopy may be applied to clinical therapeutic studies.

Proton Resonance Spectroscopy Study of the Effects of L-Ornithine-L-Aspartate on the Development of Encephalopathy, Using Localization Pulses with Reduced Specific Absorption Rate

Using the SADLOVE ( single-shot adiabatic localized volume excitation) localization technique with reduced specific absorption rate phase-compensated 2π pulses for localization, in vivo rat brain spectra were obtained in order to study the possible beneficial effects of L-ornithine-L-aspartate (OA) on the development of encephalopathy induced by hyperammonemia in portacaval shunted rats, an experimental model for subacute hepatic encephalopathy. The in vivo 1H spectra were quantified using a conjugate-gradient-based frequency-domain fitting procedure. OA treatment resulted in an about threefold lower increase in train lactate ( P < 0.0001) and a slower increase of brain glutamine ( P = 0.022) concentration. However, these changes in brain metabolism, including a significantly lower ammonia concentration during OA treatment, were not associated with a sig significant improvement in clinical symptoms of encephalopathy, suggesting either insufficient decrease in brain ammonia concentration or another effect of OA treatment counteracting the lowering effect on blood and brain ammonia and on brain glutamine and lactate. It is concluded that localized in vivo 1H MRS of the brain in combination with other analytical techniques, such as in vivo microdialysis, is helpful in explaining pathophysiological changes during hyperammonemia-induced encephalopathy.

UV-induced cross-linking of Tet repressor to DNA containingtetoperator sequences and 8-azidoadenines

The synthesis of 8-azido-2'-deoxyadenosine-5'-triphosphate is described. The photoreactive dATP analog was characterized by thin layer chromatography, proton resonance spectroscopy, infrared spectroscopy and UV spectroscopy. Its photolysis upon UV irradiation was studied. After incorporation of this dATP analog into DNA containing the tet operator sequence the investigation of the interactions between tet operator DNA and Tet repressor protein by UV photocross-linking becomes possible. Photocross-linking of protein to DNA was demonstrated by the reduced migration of the DNA in SDS polyacrylamide gel electrophoresis. Addition of the inducer tetracycline prior to UV irradiation significantly reduces the DNA-protein cross-linking rate. The long wave UV light applied here does not significantly alter the DNA or the protein under the photocross-linking conditions.

Effects of recombinant human erythropoietin on the haemopoietic bone marrow monitored by magnetic resonance spectroscopy in patients with end-stage renal disease

Volume selective magnetic resonance (MR) proton spectroscopy was used to investigate changes in the haemopoietic bone marrow in patients with end-stage renal disease undergoing treatment with recombinant human erythropoietin (rHuEPO). Significant changes could be detected in the spectra 14 days after the beginning of treatment, before any response was seen in the haemoglobin concentration of peripheral blood. The spectral changes indicate an alteration in cellular composition of haemopoietic bone marrow with an increase in the amount of haemopoietic active tissue. One patient showed a major change in the spectrum four days after treatment began, indicating that MR spectroscopy may detect early changes in the cellular composition of the bone marrow. This noninvasive method may be useful in evaluating treatment effects of recombinant human haemopoietic growth factors in the bone marrow, as well as investigating bone marrow response from different modes of rHuEPO administration.

ChemInform Abstract: Proton Resonance Spectroscopy of Unsaturated Ringsystems. Part 30. Benzo(c)‐1,7‐methano(12)annulene and Its Dianion.

AbstractThe annulene (I) and its dianion are investigated by NMR.

Ortho-diquaternary aromatic compounds. V. Chirality and structure in hindered benzenes and napthalenes

Ortho-disubstituted aromatics with bulky substituents are distorted so that the substituents are above and below the approximate plane of the aromatic system. This introduces chirality which was observed by proton resonance spectroscopy with and without the use of a chiral shift reagent. The more nearly planar naphthalene systems invert their chiral configurations more rapidly. Crystals of 1,2-benzenediacetic acid, α,α,α′,α′-tetramethyldimethyl ester are monoclinic, space group A2/a with a = 10.665(3), b = 8.467(2), c = 17.198(4) Å and β = 105.94(2)°. The torsion angle between the 1,2 substituents is 12.1°. Crystals of 2,3-naphthalene diacetic acid, α,α,α′,α′-tetramethyldimethyl ester are also monoclinic, space group P21/c with a = 9.0992(14), b = 18.849(3), c = 11.319(2) Å and β = 113.88(1)°. The analogous torsion angle in this case is 8.9°.

Elimination of solvent signals in carbon magnetic resonance spectroscopy

The problem of a strong or obscuring solvent signal in proton resonance spectroscopy was alleviated by the use of perdeuterated solvents. The practice of stabilizing the magnetic field-frequency ratio for the spectrometer via the deuterium resonance of the solvent followed from the almost routine use of deuterated solvents and was continued for carbon magnetic resonance. Perdeuterated solvents depleted in 13C were developed to remove interfering solvent signals in those cases where the reactivity of the reagents restricted the choice of solvent. However, these are expensive and only available for a few solvents. It has recently become possible to distinguish the number of hydrogen atoms directly bonded to a carbon atom by the modulation of the signal of that carbon atom in response solely to an appropriately gated proton decoupling sequence (I4). The inclusion of 180 and 90” proton pulses in the overall pulse sequence, although more complicated and demanding upon instrumentation, has been familiar longer as INEPT type experiments (5,6). With both types of pulsing sequences the spectrum can be displayed with lines arising from carbon atoms with an even number of attached hydrogens pointing down and those with an odd number pointing up. If such a spectrum is added with one obtained in the normal manner there should be complete cancellation of signals from quaternary and secondary carbons and reinforcement of signals for tertiary and primary carbon atoms. For most organic molecules the cancellation of signals from secondary and quaternary carbons is not quite complete because of long-range carbon-hydrogen coupling and because of the range of values found for one-bond carbon-hydrogen coupling constants. Therefore very weak signals are often found for them. In perdeuterated molecules the cancellation of the carbon resonance signals should be complete since there is no carbon-hydrogen spin coupling. This is illustrated in Fig. 1 for spectra acquired by the common one-pulse sequence and by the solvent signal removing sequence of Fig. 2. It can be seen that the signal of the quatemary carbon in 2-methylbutene-2 (indicated by an arrow) is not completely canceled. The deuterated tetrahydrofuran (Merck) was claimed to contain 99% deuterium. Therefore 8% of the molecules will contain one hydrogen. These are responsible for the residual solvent signals. NMR studies of model anion-pairs valuable in the investigation of

Intensity variations in two-dimensional multiquantum proton resonance spectroscopy: Design of a pulse sequence using the superspin formalism

The effect of the pulse sequence 90°− τ/2−180°− τ/2− α φ o − t 1− β o -FID upon detection of homonuclear multiple-quantum transitions was analyzed for a two-spin system. The behavior with respect to flip angle (α and β) and phase (φ, ψ) were both considered. The theoretical predictions were experimentally verified. It is shown that the above sequence is much less sensitive to choice of τ than sequences previously described.

ChemInform Abstract: PROTON RESONANCE SPECTROSCOPY OF UNSATURATED RING SYSTEMS, XXVII. THE BENZENE NUCLEUS AS A PROBE FOR THE Π‐ELECTRONIC STRUCTURE OF ANNULENES; PART IV: DEHYDROBENZOANNULENES

Chemischer InformationsdienstVolume 10, Issue 13 Physical Organic Chemistry ChemInform Abstract: PROTON RESONANCE SPECTROSCOPY OF UNSATURATED RING SYSTEMS, XXVII. THE BENZENE NUCLEUS AS A PROBE FOR THE Π-ELECTRONIC STRUCTURE OF ANNULENES; PART IV: DEHYDROBENZOANNULENES H. GUENTHER, H. GUENTHERSearch for more papers by this authorM.-E. GUENTHER, M.-E. GUENTHERSearch for more papers by this authorD. MONDESHKA, D. MONDESHKASearch for more papers by this authorH. SCHMICKLER, H. SCHMICKLERSearch for more papers by this authorF. SONDHEIMER, F. SONDHEIMERSearch for more papers by this authorN. DARBY, N. DARBYSearch for more papers by this authorT. M. CRESP, T. M. CRESPSearch for more papers by this author H. GUENTHER, H. GUENTHERSearch for more papers by this authorM.-E. GUENTHER, M.-E. GUENTHERSearch for more papers by this authorD. MONDESHKA, D. MONDESHKASearch for more papers by this authorH. SCHMICKLER, H. SCHMICKLERSearch for more papers by this authorF. SONDHEIMER, F. SONDHEIMERSearch for more papers by this authorN. DARBY, N. DARBYSearch for more papers by this authorT. M. CRESP, T. M. CRESPSearch for more papers by this author First published: March 27, 1979 https://doi.org/10.1002/chin.197913071AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue13March 27, 1979 RelatedInformation