bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proteolytic Activity of the Amoeba Mayorella Palestinensis
Authors: Edelstein S. , Lichtenstein N. , Lasman M. 
Published: November 2013

AbstractLyophilized preparations of the soil amoeba Mayorella palestinensis hydrolyzed hemoglobin. Maximum cleavage occurred near pH 3. Mercapto compounds enhanced the activity only slightly, versene and iodoacetamide had no influence. Synthetic oligopeptides were also hydrolyzed by the preparations. Maximum degree of cleavage occurred at neutral or slightly alkaline pH values. While L‐leucylglycine was readily hydrolyzed, the D‐isomer of this peptide was not attacked. With DL‐leucylglycine 50% cleavage was obtained. Carbobenzoxy‐glycyl‐L‐phenylalanine and DL‐α‐bromoisocaproyl glycylglycine were not hydrolyzed while glycyl‐L‐phenylalanine and DL‐leucylglycylglycine were readily cleaved. Hemoglobin was very poorly hydrolyzed by the preparations at neutral or slightly alkaline pH values. However, preincubation of hemoglobin with the preparations at pH 2.7 rendered it available for further appreciable hydrolysis at pH 8. The significance of these findings for understanding the process of protein digestion in the food vacuole of protozoa is discussed.
A Study on the Mechanism of the Thermal Decomposition of Ammonium Perchlorate
Authors: Burcat A. , Carmon B. , Pelly I. , Steinberg M. 
Published: November 2013

AbstractThe thermal decomposition of ammonium perchlorate in the presence of potassium chloride and chromium (III) oxide was investigated using K36 Cl and51 Cr2 O3 to elucidate the reaction mechanism. Two simultaneous routes are suggested for the decomposition. It was found that double decomposition in vacuo between potassium chloride and ammonium perchlorate does not result in the formation of potassium perchlorate. Chromium (III) oxide was not oxidized by ammonium perchlorate, but oxidation to the hexavalent state took place when potassium chloride was present.
Intermediates in the Rearrangement of O‐Aryloximes to Benzofurans
Authors: Sheradsky T. , Elgavi A. 
Published: November 2013

AbstractTwo intermediates were isolated during the cyclization of 1‐cyclohexyl‐3‐(o‐phenyloximino)‐pyrrolidine‐2‐one to 2‐cyclohexyl‐1, 3‐dihydro‐3‐oxo‐pyrrolo [3,4‐b] benzofuran. Their structures indicate that the reaction mechanism is analogous to the one proposed for the Fischer indole synthesis.
The Thermodynamics of Sodium‐Cesium Exchange on Camp Berteau Montmorillonite: An Almost Ideal Case
Authors: Cremers A. , Thomas H.C. 
Published: November 2013

AbstractAn account of the thermodynamic bases necessary for the presentation of the results of exchange sorption on colloidal materials is given. Particular attention is paid to the consequences of Henry's Law behavior in the trace regions. The arbitrary matter of standard states is briefly discussed. For a very special case, when the energy of adsorption is independent of composition, the temperature‐independent contribution to the entropy of mixing can be deduced. Results of experiments on the Na ‐ Cs exchange on Camp Berteau Montmorillonite illustrate this special case. The corresponding contribution to the free energy of exchange is small, no more than 68 calories per mole, but quite definite. It is speculated that here we have a second order effect, resulting from disparity in the sizes of the exchanging ions, due to edge effects on the clay particles.
Extrusion of Chemically Crosslinked Low‐Density Polyethylene Tubing
Authors: Miltz J. , Narkis M. 
Published: November 2013

AbstractThe conditions of extrusion of a polyethylene‐peroxide mixture in the absence of crosslinking were measured in a Brabender Plastograph. Tubing was formed in a system consisting of an extruder and a crosslinking oven, the latter vertical and directly above the extruder die, pointed upwards. The use of this geometry solved the problem of the intrinsic weight of the tubing. In the present case, the weight acts on a point above the crosslinking oven, where crosslinking to the final value takes place. The weight of the tubing is a problem when working horizontally, in which case special supports are needed, or when working vertically downwards. The main difficulties with the process as described are during startup, but these can be overcome by following a controlled series of temperature changes in the crosslinking oven until steady state is reached. At this point, the oven is isothermal for its entire length, at a temperature of 200°C. Significantly high values of rupture pressure at a high temperature can be achieved for crosslinked tubing containing a filler.
Analytical Applications of the Mercury Coated Rotating Platinum Electrode (MCRPE)
Authors: Koster G. , Ariel M. 
Published: November 2013

AbstractThe combined use of the method of Medium Exchange and a platinum electrode covered by a thin mercury film significantly extends the range of applications of anodic stripping volt‐ammetry. A thin nickel film, interposed between the platinum and the mercury, improves the keeping qualities of the mercury film and facilitates its electro‐deposition. The new technique, among whose advantages increased sensitivity and convenience may be cited, provides a further stepping stone towards the adaptation of anodic stripping for use in the routine analysis of complex samples.
Application of Vapor Pressure Osmometry to the Study of Uranyl Nitrate and Thorium Nitrate Complexes with Tributyl Phosphate
Authors: Apelblat A. , Hornik A. 
Published: November 2013

AbstractMolecular weights of uranyl nitrate and thorium nitrate solutions in TBP were determined using vapor pressure osmometry. The results seem to show that in carbon tetrachloride uranyl nitrate forms a di‐solvate only, whereas in acetone solution this complex is partly dissociated. Thorium nitrate results have been explained assuming a mixture of two complexes with TBP‐a di‐solvate and a tri‐solvate. The equilibrium constant for the reaction Th(NO3)4 · 2TBP + TBP ⇄ Th(NO3)4 · 3TBP was found to be Kx = 30 at 25°C.
Fulvenes and Thermochromic Ethylenes, Part 53 The Fine Structure of 2‐Arylmethylene‐1,3‐Indandiones; their Dipole Moments and Electronic Spectra
Authors: Weiler‐Feilchenfeld Hannah , Loewenstein Ruth M. J. , Agranat I. , Bergmann E. D. 
Published: November 2013

AbstractThe molar refractions (polarizabilities) and dipole moments of fourteen 2‐arylmethylene‐1,3‐indandiones (I) and the electronic absorption spectra of twenty‐one representatives of this series have been measured. From these data certain features of the fine structure of the compounds have been deduced; inter alia, the carbonyl groups in I are bent away from the benzene ring of the indane moiety, and the 4‐dimethylaminophenyl compound II exists to a significant extent in the zwitterionic form IIA.
Photochromism in Dianthrone and Related Compounds. Part III. Solutions in Aliphatic Hydrocarbons
Authors: Bercovici T. , Fischer E. 
Published: November 2013

AbstractThe photochromism of four non‐thermochromic derivatives of dianthrone, in nonpolar solvents, was investigated. Photocoloration takes place with quantum yields close to unity at temperatures down to −160°C. No photodecoloration takes place. Thermal decoloration is a first‐order reaction, with activation energies of about 13–14 kcal mole−1. At very low temperatures and high viscosities the quantum yield of photocoloration drops sharply, and a new unstable colored modification is formed. The latter converts spontaneously into the normal colored form, at somewhat higher temperatures. Flash experiments show that photocoloration at room temperature takes place within the lifetime of the flash (ca. 5 μs), but this is no longer so at low temperatures.
Internal Conversion in Polyatomic Molecules
Authors: Teller E. 
Published: November 2013

AbstractIt is argued that efficient internal conversion in polyatomic molecules occurs when the energy gap between two potential energy surfaces is sufficiently small, so that, at finite nuclear velocities, the corrections to the Born‐Oppenheimer approximation can lead to significant transition probabilities. In particular this will occur near a conical intersection of two surfaces. An estimate of the transition probability is provided using the Zener criterion.
“Predissociation and Preionization Lifetimes of Polyatomic Ions in the Gas Phase”
Authors: Lifshitz Chava 
Published: November 2013

AbstractExperimental results concerning predissociations of polyatomic positive ions in the gas phase are reviewed. These include the observation of “metastable” ions; photoionization efficiency curves; “metastable” ion decay curves and isotope effects. Examples are given for the three cases of predissociation. Predissociation by vibration is treated in greater detail and the data are compared with predictions of the quasi‐equilibrium theory (QET). Results concerning preionization of polyatomic negative ions are also included. The theoretical treatment of this problem is presented and discussed. Suggestions are made as to possible future developments in this field.
Study of the Water Molecule in the Gaseous Phase Excited States of H2O, H2O+ and H2O−
Authors: Fiquet‐Fayard F. 
Published: November 2013

AbstractA short account of the electron configuration of water, including symmetry properties, is given. These simple considerations permit the explanation of the results of photoelectron spectroscopy experiments and photoionization experiments; the 2B2 state of H2O+ is predissociated. Excited states of water are all repulsive or predissociated, the more important fragments being OH2τ, OH2Σ+ and O. Some repulsive states of H2O− are known, but the important low‐lying 2A′ state is unknown.
Pressure Broadening of Line Spectra
Authors: Ben‐Reuven A. 
Published: November 2013

AbstractA brief survey is given of pressure broadening theory, with particular attention to impact phenomena. The basic collision processes that contribute to line broadening (such as phase shifts, amplitude modulation, reorientation, and sense reversal) and their effects are discussed. Subsequent line shape expressions for the broadening of resonance lines and the transition to nonresonant line shape are presented.
Simplistic Analysis of Reactive Scattering
Authors: Levine R. D. , Bernstein R. B. 
Published: November 2013

AbstractThe relation between the angular distribution of the non‐reactively scattered molecules in a reactive collision and the reaction probability is analyzed in terms of a classical grey sphere “optical model”. Computational results for a model problem are discurred, and the inversion procedure, for the deduction of an opacity function (reaction probability vs. impact parameter) from an observed and a reference angular distribution, is tested. It is concluded that a simple phenomenological analysis of experimental angular distributions can be based on such an optical model.
Oxidation of Cyclanols by VV
Authors: Radhakrishnamurti P. S. , Pati S. C. 
Published: November 2013

AbstractThe kinetics of oxidation of cyclanols by Vv in acetic acid ‐ water mixtures at constant acidity is reported. The results are discussed in the light of I strain hypothesis. The postulated mechanism of Waters for cyclanol oxidation is also discussed with reference to this series of alcohols.
Reactions of Some Clays with Ferric‐Ferricyanide (Prussian Brown)
Authors: Yariv S. 
Published: November 2013

AbstractThe intensification of the auto‐reduction of Prussian Brown by clay minerals was studied. The reaction is catalyzed mainly by the expanding clay minerals montmorillonite and vermiculite, but is inhibited by aluminium oxide and allophane, although these also sorb Prussian Brown. The influence of surface acidity and exchangeable cation on the reaction is discussed.
Pyrolytic Reactions of Carbohydrates. Part IV. Anhydro‐Sugar Formation and Transglycosylation in the Thermal Reactions of Various Glucose Derivatives
Authors: Houminer Y. , Patai S. 
Published: November 2013

AbstractThe formation of levoglucosan and 1,6‐anhydroglucofuranose in the thermal decomposition of glucose derivatives, such as methyl and phenyl glucosides and oligosaccharides was studied. It was found that the cleavage of glucosidic linkages in general involves both transglycosylation and hydrolysis. Some conclusions relating to the thermal stability of the various glucosides were drawn and the mechanisms of the reaction are discussed.
Aminolysis and Polymerization of 3‐(p‐Toluenesulfonoxy)Hydantoin
Authors: Zvilichovsky G. , Zucker B. 
Published: November 2013

AbstractAminolysis of 3‐(p‐toluenesulfonoxy)hydantoin (I) through two alternative routes led to the formation of series of both methylene‐diurea derivatives(II) and ω‐arylsemicarbazido (N‐arylacetamides) (III). 3‐(p‐Toluenesulfonoxy)hydantoin was found to undergo a novel kind of polymerization reaction induced by triethylamine, yielding a new polymer structure which consists of hydantoin groups combined by a hydrazinic linkage. 5‐Isopropyl‐3‐(p‐toluenesulfonoxy) hydantoin (IV) was prepared here from α‐isopropylmalonic acid diethyl ester, via α‐isopropylmalonohydroxamic acid (V); properties of this compound were also studied.
Stable and Transient Spectra in Pulse Irradiated Metaphosphate Glasses
Authors: Rabani J. , Ottolenghi M. 
Published: November 2013

AbstractPulse radiolysis of pure metaphosphate glasses yields a transient spectrum with a maximum at 580 run. This new absorption overlaps that of the permanent coloration at 500nm. The decay of the 580nm species extends over a very large time interval, from ∼10−7 sec to ∼10−2 sec. The effects of doping the glass with CdSO4 and Ce2(SO4)3 are reported and analyzed. The results are interpreted in terms of various electron and hole centers. It is suggested that non homogeneous (spur or cage) kinetics is responsible for the 580 nm decay.
Speculations on a New Mechanism of Crystal Growth from Aqueous Solutions
Authors: Glasner A. 
Published: November 2013

AbstractThe activity of lead ions to form heterogeneous nuclei in supersaturated KCl solutions was shown (in previous publications) to account quantitatively for the effect of these ions on the limit of stability of the supersaturated solutions, the rate of crystallization, and the co‐precipitation of the lead ions with the crystallizing salt. Hence the process of crystal growth is described as the deposition of subcolloidal sized nuclei on the crystal seed. Many otherwise perplexing phenomena recorded in the literature, and observed in studies of various aspects related to the crystallization of KCl and NaCl, prove to be a direct consequence of this mechanism of crystallization. Other examples indicate that heteronucleation and a similar growth mechanism may be prevalent in the crystallization of several salts from their aqueous solutions. Some implications and possible applications of the proposed growth mechanism are also discussed.
Pyrolytic Reactions of Carbohydrates. Part VII. Simultaneous DTA‐TGA Study of the Thermal Decomposition of Cellulose In Vacuo
Authors: Halpern Y. , Patai S. 
Published: November 2013

AbstractThe decomposition of cellulose, in the absence and presence of additives, has been studied in a combined DTA‐TGA (differential thermal analysis — thermogravimetric analysis) system, in which both determinations were carried out simultaneously and on the same sample. The overall process was found to be endothermic in untreated cellulose and in the presence of acidic catalysts, but changed into an exothermal one in the presence of strong bases.
Homogeneous Catalytic Isomerization of Allylbenzene and Phenylbutenes by Some Platinum‐Metal Oomplexes
Authors: Blum J. , Pickholtz Y. 
Published: November 2013

AbstractThe isomerization of Allylbenzene, p‐allylanisole, 4‐phenylbut‐1‐ene and trans‐1‐phenylbut‐2‐ene catalyzed by various ruthenium, rhodium and iridium complexes has been investigated. At the boiling point of the olefins the reaction does not require co‐catalysts. The activity of the complexes studied decreases in the order Ru > Ir > Rh. PPh3 and AsPh3 increase the initial rates of the Rh (III), catalyzed reactions, decrease the activities of Rh (I)‐ and Ir (I)‐complexes and do not affect the Ru (II)‐compound. Different mechanisms for the rhodium‐ and ruthenium‐catalyzed isomerizations are suggested.
Liquid Phase Oxidation of 1, 4 and 1, 2‐Dihydronaphthalene
Authors: Martan M. , Manassen J. , Vofsi D. 
Published: November 2013

AbstractThe two isomeric olefins, 1,2 and 1,4‐dihydronaphthalene, were subjected to autoxidation. Although rates as well as product patterns were entirely different for both olefins, it could be shown that an α‐peroxy radical is a common intermediate with both substrates. The difference in behaviour is caused by the fact that with the 1,4‐isomer chain propagation takes place by hydrogen abstraction, while addition to the reactive double bond occurs with the 1,2‐isomer. By cooxidation experiments of the two olefins a high conversion into an epoxide could be obtained, which was shown to be a reaction intermediate in the formation of β‐tetralone from the 1,2‐isomer. The products obtained on cobalt ion catalyzed oxidation were in agreement with the accepted mechanism for this reaction. The fact that attack by oxygen with both isomers occurs only at the α‐position is contrary to what could be expected on the basis of the thermodynamic stability of the products, but is in agreement with the recently proposed principle of least motion. With base catalysis almost exclusively the dehydrogenation product naphthalene was obtained.
The Radiolysis of Methanol and Methanolic Solutions. VI. Cis and Trans‐Stilbene
Authors: Loeb Anne M. , Lichtin N. N. 
Published: November 2013

AbstractThe use of geometrical isomerization of stilbene as a monitor of radiolytic excitation in methanolic solutions was evaluated using gas chromatographic analysis. No evidence for excitation of stilbene was obtained. The mechanistic significance of the observed isomerization of trans‐stilbene is obscured by the preponderant simultaneous formation of a veriety of other products. The cis‐stilbene used in this work was much less sensitive to ionizing radiation than its trans‐isomer, presumably because of efficient protection by a few percent of 2‐methylnaphthalene present as an impurity.
The Anomalous Behaviour of 18O‐Labelled Compounds. Part IV. Vibrational Spectra of Isotopic Vanadate Ions
Authors: Pinchas S. , Shamir J. 
Published: November 2013

AbstractThe Raman spectra of crystalline hydrated normal and 80 atom% 18O‐labelled sodium orthovanadates were investigated, the bands observed thus being assigned to their respective original modes of vibration. The Raman bands of the aqueous solutions of these vanadates, containing mainly the respective HVO4−2 or DVO4−2 ions, were also studied and in most cases observed to rise in frequency as a result of the 18O‐labelling, as expected on the assumption that the hydrogen bonding between the solvating water molecules and the vanadate ions is weakened by 18O‐labelling the latter.
Thermal Decomposition Kinetics of Ammonium Perchlorate by TGA in Air
Authors: Simchen A. E. 
Published: November 2013

AbstractTGA curves were obtained in air at atmospheric pressure, at constant and at uniformly increasing temperatures, for small samples of ammonium perchlorate (AP): (A) AP less than three weeks from its recrystallization; (B) AP four to seven months old; (C) pellets of aged material of known grain size. Activation energies calculated from the kinetic evaluation of the TGA curves show differences between the three groups of samples. The greatest activation energies were obtained for group A, the smallest for group C. The “limited decomposition” of AP below 300°C is lowest for group A; it is below 20% as opposed to above 30% for the other two groups. The reaction controlling the weight loss is of second order. An explanation of these facts is attempted by suggesting an activation energy contribution of lattice defects formed on ageing.
A Nitrogen‐Laser Photolysis Apparatus in the Nanosecond Range: The Excited Singlet‐Singlet Absorption Spectrum of Coronene
Authors: Goldschmidt C. R. , Ottolenghi M. , Stein G. 
Published: November 2013

AbstractThe application of a low energy pulsed nitrogen laser as a fast excitation source in photochemistry is described. The experimental problems concerning detection of transients by absorption spectroscopy are discussed. The instrument is applied to the measurement of the absorption spectrum curve of coronene in its lowest excited singlet state.
An Investigation of Proteohormones by Alternating Current Polarography
Authors: Goldstein Rahel , Königsbuch M. 
Published: November 2013

AbstractThe behavior of some proteohormones as mixtures of FSH and LH at different proportions and purity was studied by polarography. Proteins which contain groups of ‐SH and/or ‐S‐S‐, develop in an ammoniacal buffer of CoII or CoIII salts a typical double wave, which is believed to be a catalytic wave of hydrogen evolution. It is called a Brdicka double wave. It depends on various parameters such as concentration of the protein, pH, buffer capacity, temperature, height of mercury current, etc. The influence of changing the various parameters on the height of the wave and on the potential of the maximum of the wave height was studied. Comparison was made among the various hormones and with the simple protein human albumin. The measurements were performed by direct current and alternating current polarography. An attempt is made to investigate the mechanisms of each of the two components of the double wave. Hormone preparations, containing different proportions of LH and FSH, could be characterized.
Photochemistry and Structure of Metal Amine Solutions
Authors: Gaathon A. , Ottolenghi M. 
Published: November 2013

AbstractThe photochemistry of the 670 nm band in fluid sodium amine solutions is investigated by applying flash (optical detection) or steady state (ESR detection) irradiation techniques. The photoregeneration of faded alkali metal solutions induced by exciting the amide decomposition product, is also submitted to flash investigation. In both cases the primary act appears to be the generation of solvated electrons. The available photochemical data are examined in light of a recent spectroscopic study which attributes the 670 nm band to a sodium anion (Na−) and the 850, 920 and 1030 metal bands to K−. Rb− and Cs−, respectively. It is concluded that the photochemical observations provide new evidence for the model involving the alkali metals negative ions. Electron photoejection in a rigid amine glass at −196°C produces a (IR) band which is red shifted relative to that present in an equilibrium liquid solution, frozen to the same low temperature glass. The effect is attributed to two, physically distinguishable, solvated electrons in glasses or, alternatively, to an additional (unidentified) IR species present in the dark equilibrium solutions.