bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some N‐Substituted 6‐Methylpurines
Authors: Vincze A. , Cohen Sasson 
Published: November 2013

Abstract6,9‐Dimethylpurine was prepared from 6‐methyluracil; the key step in this procedure is the selective amination of 2,4‐dichloro‐5‐nitro‐6‐methyluracil with methylamine. Methylation of 6‐methylpurine, gave a mixture of 6,9‐dimethyl‐and 3,6‐dimethyl‐purine, separable by column chromatography. An improved procedure for the preparation of 6‐methyl‐9‐(β‐D‐ribofuranosyl) purine is presented.
Direct Spectrophotometric Determination of Iron in the HCl Soluble Fraction of Carbonate Rocks
Authors: Avinur P. , Yaalon D. H. , Barzily I. 
Published: November 2013

AbstractA method is presented for the direct determination of iron in the HCl soluble fraction of carbonate rocks. Use is made of the absorbance‐difference technique as developed by Glasner and Avinur, whereby the chloroferrate absorbance of the solution is measured at two wavelengths and the difference of absorbance between them is made the basis of the determination. Determination of iron by the chloroferrate absorbance when measured at only one wavelength was found to be impeded by the variation of the absorbance with the following factors: the ratio of chloride salt to free HCl; the nature of the chloride salt (Ca or Mg); slight changes in the total chloride concentration; and temperature. All these difficulties were largely overcome by the application of the absorbance‐difference technique.
The Reaction of α‐Ketophosphonates with Organometallic Compounds and Sodium Borohydride
Authors: Shahak I. , Bergmann E.D. 
Published: November 2013

AbstractIn α‐ketophosphonates, only the carbonyl group reacts with metal‐organic reagents. The resulting α‐ hydroxyalkyl‐ and α‐aryl‐α‐hydroxymethylphosphonates are hydrolysed to ketones. A side‐reaction, sometimes predominant, is the reduction of the carbonyl group in the starting materials. This is better achieved by means of sodium borohydride. The products can be hydrolysed to aldehydes or reduced to the corresponding hydrocarbons.The reactions of ethyl diethoxyphosphinylformate with Grignard compounds have been studied.
7‐Methoxyindole and its Derivatives
Authors: Kalir A. , Balderman D. , Edery H. , Porath Gila 
Published: November 2013

Abstract7‐Methoxyindole was prepared by reductive cyclization of 3‐methoxy‐2, β‐dinitrostyrene. The synthesis and pharmacological properties of several 7‐methoxytryptamines are described.
On the Use of the Molar Ratio Method for Determining Association Stoichiometry
Authors: Marcus Y. 
Published: November 2013

AbstractIn the molar ratio method, a property of a solution is plotted against the molar ratio of the two reactants, the concentration of one being kept constant. The stoichiometry of the complex or complexes formed is deduced from the position of breaks in the curve. The method is examined critically, and is shown to be inapplicable to most problems, owing to the nonrealization of the required assumptions of linear dependence of the property on the partial molar properties of the interacting species and constancy of activity coefficients, in addition to the mathematical difficulties involved in relating the breaks in the curves to the stoichiometric ratio in the complex.
The Determination of Titanium by Tiron in the Presence of Large Amounts of Calcium and Iron. II
Authors: Barzily I. , Yaalon D. H. , Avinur P. 
Published: November 2013

AbstractThe effect of varying concentrations of neutral salts on the initial pH of maximum color in the colorimetric determination of Ti by tiron was studied. A direct method was developed for the determination of Ti in the presence of great amounts of Ca and Fe. The various reducing or masking agents used for the prevention of the interference of iron were discussed. Many ions were found not to interfere, and the limiting tolerance of others was given. The method may find application in the determination of Ti in rocks and alloys.
Selective Removal of the Benzyl Group from Position 3 of Purines
Authors: Neiman Z. , Bergmann F. 
Published: November 2013

Abstract3‐Benzylpurines with a free 2‐position undergo debenzylation when heated with 48% hydrobromic acid for a few minutes; benzyl groups linked to other nitrogen atoms are not removed. The reactive species is probably the resonating cation formed by attachment of a proton to N‐1.Selective 3‐debenzylation is a useful method for the synthesis of 7‐alkylpurines.
Ion Exchange in Molten Salts. II: The Occlusion of Lithium, Sodium, Potassium and Silver Nitrates in the Respective Forms of Zeolite A.
Authors: Liquornik M. , Marcus Y. 
Published: November 2013

AbstractThe occlusion of lithium, sodium, potassium and silver nitrates from the anhydrous melts in the respective zeolites has been studied by measuring the gain in weight and by direct analysis. The results in moles of occluded nitrate per formula weight of zeolite M12I[(AlO2)12(SiO2)12] are 11.7 for LiNO3, 10 for NaNO3 and 10 for AgNO3 and essentially zero for KNO3. A model is proposed for the structure of the occlusion compound Na22[(AlO2)12(SiO2)12(NO3)10], in terms of four NaI+ ions and four [NaI ‐ NO3 ‐ Na]+ groups at the apexes of the cubic unit cell and four [NaII ‐ NO3 ‐ Na]+1/3 groups coordinated with two [NaNO3]−2/3 groups at the faces, to explain the properties of the occluded zeolites.
Heterocyclic Hydroxylamine Derivatives II: Synthesis and Properties of 1‐(2‐Oxopyrimidino)Oxyacetic Acid 1‐Hydroxy‐2‐Oxopyrimidine and their Derivatives
Authors: Zvilichovsky G. 
Published: November 2013

Abstract1‐(2‐Oxopyrimidino) oxyacetic acid (I) and 1‐hydroxy‐2‐oxopyrimidine (VI) have been synthesized from 1, 1, 3, 3‐tetraethoxypropane and the appropriate urea derivatives. Dissociation constants, IR and UV spectra of the acid (I), the 1‐hydroxy derivative (VI) and their derivatives were studied.
Benzyl Chloride‐Amine Reaction in Nitrobenzene‐Ethanol Mixture
Authors: Radhakrishna Murti P. S. , Panigrahi G. P. 
Published: November 2013

AbstractThe reactions between benzyl chloride and various bases as well as p‐nitrobenzyl chloride and various bases have been studied in nitrobenzene‐ethanol mixtures. The reaction is total second order as found earlier.
Displacing Exchangeable Potassium in Cation Exchange Determinations
Authors: Yaalon D. H. , Koyumdjisky Hanna 
Published: November 2013

AbstractThe amounts of exchangeable K displaced by NH4, Na, and Li using methods adopted in cation exchange determinations were compared. Besides differences due to the effect of the geometric factor of the replacing ion, related to its size and hydration characteristics, the behaviour of clays of two groups of soils was consistently and significantly different. A critical assessment of the data suggests that there is a considerable diversity in the distribution and bonding energy of the K adsorption sites on the various clays.
Fluctuational Variation in the Relationship Between Water Capacity and Soil‐Water Suction
Authors: Bazargani J. I. , Swartzendruber D. 
Published: November 2013

AbstractThe relationship between the water content of a soil and the suction component of the water‐moving potential, expressible either as the water‐retention curve or the water‐capacity function, is often tacitly expected to decrease smoothly and monotonically with increasing suction, once the maximum water capacity has been reached. For two nonswelling artificial soils, a calcined clay and a sand‐kaolinite, the general position of the water retention curve was found to be essentially the same regardless of the size of the suction increment applied in obtaining the curve. The water‐capacity function, computed as the incremental reduction in water content per unit increase in suction head, was also found to be essentially smooth and monotonically decreasing with increasing suction when the applied suction increments were relatively large (≥ 100 mb), but consistent and marked fluctuations were found when the decrements of water content and increments of suction were small (suction steps of 50 and 25 mb). Concerning possible causes of this fluctuating behavior, it is suggested that the microbehavior of pore‐water removal might be failing to average out statistically to a monotonically smooth macrobehavior, or that if water properties were modified by particle‐water interaction such as to induce threshold gradients for water flow, effects of this nature might somehow be involved.
Constituents of Huleh Peat. III. Acids
Authors: Ikan R. , Stahl G. , Bergmann E. D. 
Published: November 2013

AbstractHydrolysis of the waxy fraction of Huleh peat, esterification of the acid mixture and application of thin‐layer chromatography, gas chromatography, mass and infrared spectroscopy and catalytic hydrogenation techniques revealed the presence of a series of even‐ and odd‐numbered saturated acids and several unsaturated acids.
The Aluminum Alkoxide Rearrangement of Epoxides, Part I: The Synthesis of Allylic Alcohols and Glycols Monoethers
Authors: Eschinasi E.H. 
Published: November 2013

AbstractThe rearrangement of epoxides catalyzed by aluminum alkoxides affords a selective way of preparing allylic alcohols in high yields. It takes place in the presence of catalytic amounts of aluminum isopropoxide (AIP) which leads to cleavage of the ether linkage at the site of the more substituted α‐carbon of the oxirane. A mechanism with a six membered transition state involving a concerted proton transfer from the least substituted carbon in β position of the oxirane oxygen is suggested. Mild conditions are sufficient to promote this rearrangement to allylic alcohols with epoxides having a tertiary carbon in α‐position of the oxirane oxygen. However, alkoxide transfer to the cleaved α‐carbon may take place when primary or secondary carbons are the only ones present in the α‐positions of the oxirane oxygen with more drastic conditions and equimolar amounts of AIP. The major product is a mixture of α‐glycol monoethers.
Biochemical Changes in Organs of Chicks and Rats Poisoned with Ethylene Dibromide and Carbon Tetrachloride
Authors: Nachtomi Edna , Alumot Eugenia , Bondi A. 
Published: November 2013

AbstractThe following biochemical parameters were determined in the livers of rats and chicks which had been previously treated with ethylene dibromide (EDB) and carbon tetrachloride: sulfhydryl groups, ascorbic acid, nicotinamid‐adenine‐dinucleotides (NAD and NADP) and alkaline phosphatase. Ascorbic acid levels were also determined in adrenals and alkaline phosphatase activity in blood. A marked depression in the level of free sulfhydryl groups was observed in the livers of the two species during the first hours after poisoning. The initial drop in the SH level was followed by a subsequent rise, the rate of which differed with species, sex, and poison. Carbon tetrachloride treatment resulted in a very marked depression of ascorbic acid content in rat liver while EDB caused only a slight depression. The ascorbic acid content of chick liver was less affected by the two poisons as was the liver NAD (P) content of both species. A rise of alkaline phosphatase was found with both poisons in rat liver in contrast to depression of the enzyme activity in chick liver. Rats and chicks responded differently to toxic action of the two poisons. This may be related to the different metabolism of the poisons in the two species.
Michael Addition Reactions of a β‐Ketosulfoxide
Authors: Bergmann F. , Diller D. 
Published: November 2013

Abstractω‐Methylsulfinylacetophenone can be added to acrylonitrile or ethyl acrylate in the presence of Triton B. The resulting sulfoxides (II) are oxidised by hydrogen peroxide to the sulfones (III) and are reduced by aluminum amalgam to γ‐benzoylbutyronitrile or the corresponding butyric acid. The structures assigned are supported by infrared spectra.
Energy Transfer in Molecular Collisions
Authors: Levine R.D. 
Published: November 2013

AbstractComputational studies of energy transfer in models of molecular collisions are presented and analyzed qualitatively and semi‐quantitatively. Particular attention is given to those approximations where the leading term is already in good qualitative agreement with the exact numerical results. In particular, results for the distorted wave approximation in an adiabatic basis are reported and compared with the exact results. It is argued that for slow molecular collisions, the efficiency of the transfer is determined by the “Franck Condon” overlap near the repulsive part of the intermolecular potential.
ESR Studies of Uncomplexed and Complexed HO2 Radical Formed in the Reaction of H2O2 with Ce4+, Fe2+ and Ti3+ Ions
Authors: Czapski G. , Levanon H. , Samuni A. 
Published: November 2013

AbstractExcess of H2O2 reacting in 0.5N HClO4 with Ce4+, Ti3+ and Fe2+ yields the uncomplexed HO2 radical. This radical gives a broad ESR signal with a line width of 27±1 gauss and a g‐value of 2.0140±0.0015. The HO2 radical forms a complex with excess of Ce3+ which gives an ESR spectrum with a linewidth of 1.3±0.1 gauss and a g‐value of 2.0180±0.0005. The equilibrium between complexed [Ce3+‥HO2] and uncomplexed HO2 was studied. Two complexes are formed between HO2 and [Ti4+…H2O2]. These complexes give two ESR signals with a linewidth of 0.7 ± 0.1 and 0.5± 0.1 gauss and g‐value of 2.0140± ± 0.0005 and 2.0120± 0.0005 respectively.
Propellanes VIII. Electrocyclic Reactions of Tetraenic Propellanes
Authors: Altman Janina , Babad Esther , Ginsburg D. , Rubin M. B. 
Published: November 2013

AbstractThe electrocyclic reaction sequence of tetraenic propellanes is analogous to that of their parent, cis‐9,10‐dihydronaphthalene as a member of the (CH)10 family. Irradiation of Ia‐e afforded IIa‐e of which IIb and IIc have been isolated. These are the first stable derivatives of tetracyclo [4.4.0.02,10.05,7]deca‐3,8‐diene. Thermal bond‐realignment of IIa‐e led, due to fluxional isomerism in prebullvalene and its derivatives, to prebullvalenes of the III series. Only in the case of the prebullvalene lactone was it possible to observe IVd alongside of IIId in its room terperature NMR spectrum. Irradiation of the prebullvalene ether IIIe afforded a bullvalene ether which at low temperature shows the presence of XIII (R=R=−CH2‐O‐CH2‐) and XV.
Dipole Moment and Spectroscopic Properties of 2‐Ferrocenylmethylene‐1, 3‐Indandione
Authors: Agranat I. , Weiler‐Feilchenfeld Hannah , Loewenstein Ruth M. J. 
Published: November 2013

AbstractThe electric dipole moment and the NMR, infrared and electronic spectra of 2‐(ferrocenylmethylene)‐1, 3‐indandione (I) indicate that a dipolar structure (such as II or III) contributes significantly to the ground state of the molecule.
An Approach to the Enzymatic Cleavage of Serine Peptide Bonds
Authors: Patchornik A. , Wilchek M. , Zioudrou C. 
Published: November 2013

AbstractThe reaction of O‐p‐toluenesulfonyl and O‐methanesulfonyl‐L‐serine peptides with cysteamine yields the corresponding S‐β‐aminoethylcysteine peptides (thialysine peptides). The thialysine peptides can be hydrolysed by trypsin. The method can be used for sequence studies.
Fluorescence of Gd+++ in Alkali Halide Crystals
Authors: Mustachi A. , Reisfeld R. , Glasner A. 
Published: November 2013

AbstractCrystals of potassium chloride and potassium bromide containing trivalent gadolinium were prepared from the melt and also by heating the powdered anhydrous mixtures at 600°C. Their fluorescence spectra consisted of four sharp lines around 3114.3 Å and 3115.1 Å respectively. A single mode of charge compensation for the substituted Gd3+ ion with a D3h or C2v symmetry is proposed. Lifetimes of the fluorescence of these doped crystals as well as of pure GdCl3 and GdBrs are of the order of a few msec.
On the Mechanisms of X‐Ray‐Induced Excitation of Aromatic Molecules in Polar Solution
Authors: Steen H. B. 
Published: November 2013

AbstractStudies of the X‐ray‐ and UV‐induced luminescence of tryptophan and tyrosine in solution between 77°K and 300°K are reviewed. The fluorescence and phosphorescence spectra observed during X‐irradiation are identical to those induced by UV light, but the phosphorescence to fluorescence ratios obtained with X‐rays are much larger than those found with UV light. The experiments seem to show that charge recombination is the dominating mode of the X‐ray‐induced excitation at low temperatures, giving rise to roughly 85% of the X‐ray‐induced luminescence at 77°K. The fraction of the X‐ray‐induced excitation which results from charge recombination decreases with increasing temperature and becomes negligible above 220°K. This causes the yield of X‐ray‐induced excitation of the radiative levels of tryptophan to decrease from G = 5 excited molecules/100 eV absorbed in solute, at 77°K, to G = 0.4 at room temperature. The mechanisms for quenching of charge recombination are discussed.
Environmental Effects on the Fluorescence of Tryptophan and Other Indole Derivatives
Authors: Feitelson J. 
Published: November 2013

AbstractThe fluorescence quantum yields of tryptophan, 3‐methylindole and 3‐β‐hydroxyethylindole were investigated as a function of temperature in a variety of polar and non polar solvents. Similar quantum yields and “activation energies” were found for the different systems. It was concluded that the same collisional solvent deactivation is responsible for the decrease in quantum yield with temperature irrespective of solvent system used. A notable exception is water where a different mechanism is indicated. The quenching of the indole chromophore fluorescence by a variety of specific agents both attached to the ring by an ethylene bridge and in homogeneous solution was also studied. It was found that potential proton donating groups were good quenching agents, the effect being much greater for groups carrying a positive charge. Polarization by a neighboring group also enhanced the quenching ability of any specific group. It was concluded that an excited state charge transfer complex is probably involved as a first step in the quenching process.
Investigating the experiences of New Zealand MRI technologists: Exploring intra‐orbital metallic foreign body safety practices
Authors: Jacobs Philippa K. , Henwood Suzanne 
Published: November 2013

AbstractIntroductionQualitative research is lacking regarding the experiences of magnetic resonance imaging (MRI) technologists and their involvement in workplace safety practices. This article provides a gateway to explore, describe and document experiences of MRI technologists in New Zealand (NZ) pertaining to intra‐orbital metallic foreign body (IMFB) safety practices.MethodsThis phenomenological study describes the experiences of seven MRI technologists all with a minimum of 5 years' NZ work experience in MRI. The MRI technologists were interviewed face‐to‐face regarding their professional IMFB workplace experiences in order to explore historical, current and potential issues.ResultsFindings demonstrated that aspects of organization and administration are fundamentally important to MRI technologists. Varying levels of education and knowledge, as well as experience and skills gained, have significantly impacted on MRI technologists’ level of confidence and control in IMFB practices. Participants’ descriptions of their experiences in practice regarding decision‐making capabilities further highlight the complexity of these themes. A model was developed to demonstrate the interrelated nature of the themes and the complexity of the situation in totality.ConclusionsFindings of this study have provided insight into the experiences of MRI technologists pertaining to IMFB safety practices and highlighted inconsistencies. It is hoped that these findings will contribute to and improve the level of understanding of MRI technologists and the practices and protocols involved in IMFB safety screening. The scarcity of available literature regarding IMFB safety practices highlights that more research is required to investigate additional aspects that could improve MRI technologists’ experiences.
Absent movement‐related cortical potentials in children with primary motor stereotypies
Authors: Houdayer Elise , Walthall Jessica , Belluscio Beth A. , Vorbach Sherry , Singer Harvey S. , Hallett Mark 
Published: November 2013

ABSTRACTThe underlying pathophysiologic mechanism for complex motor stereotypies in children is unknown, with hypotheses ranging from an arousal to a motor control disorder. Movement‐related cortical potentials (MRCPs), representing the activation of cerebral areas involved in the generation of movements, precede and accompany self‐initiated voluntary movements. The goal of this study was to compare cerebral activity associated with stereotypies to that seen with voluntary movements in children with primary complex motor stereotypies. Electroencephalographic (EEG) activity synchronized with video recording was recorded in 10 children diagnosed with primary motor stereotypies and 7 controls. EEG activity related to stereotypies and self‐paced arm movements were analyzed for presence or absence of early or late MRCP, a steep negativity beginning about 1 second before the onset of a voluntary movement. Early MRCPs preceded self‐paced arm movements in 8 of 10 children with motor stereotypies and in 6 of 7 controls. Observed MRCPs did not differ between groups. No MRCP was identified before the appearance of a complex motor stereotypy. Unlike voluntary movements, stereotypies are not preceded by MRCPs. This indicates that premotor areas are likely not involved in the preparation of these complex movements and suggests that stereotypies are initiated by mechanisms different from voluntary movements. Further studies are required to determine the site of the motor control abnormality within cortico‐striatal‐thalamo‐cortical pathways and to identify whether similar findings would be found in children with secondary stereotypies. © 2013 International Parkinson and Movement Disorder Society
Curative diet supplementation with a melon superoxide dismutase reduces adipose tissue in obese hamsters by improving insulin sensitivity
Authors: Carillon Julie , Knabe Lucie , Montalban Anne , Stévant Marie , Keophiphath Mayoura , Lacan Dominique , Cristol Jean‐Paul , Rouanet Jean‐Max 
Published: November 2013

ScopeObesity‐related metabolic syndrome is often associated with a decrease of insulin sensitivity, inducing several modifications. However, dietary antioxidants could prevent insulin resistance. We have previously shown the preventive effects of a melon superoxide dismutase (SOD) in obese hamsters. However, its antioxidant effects have never been studied on adipose tissue.Methods and resultsWe evaluated the effects of a 1‐month curative supplementation with SODB on the adipose tissue of obese hamsters. Animals received either a standard diet or a cafeteria diet for 15 wk. Cafeteria diet induced obesity and related disorders, including insulin resistance and oxidative stress, in the abdominal adipose tissue. After SODB supplementation, the adipose tissue weight was decreased, probably by activating adipocytes lipolysis and thus reducing their size. SODB treatment also resulted in abdominal adipose tissue fibrosis reduction. Finally, SODB administration increased the expression of endogenous antioxidant enzymes and thus reduced oxidative stress and insulin resistance. The improvement of insulin sensitivity observed after SODB treatment could explain adipocyte lipolysis activation and fibrosis reduction.ConclusionThese findings demonstrate that a dietary SOD supplementation could be a useful strategy against obesity‐related modifications in adipose tissue.