bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption Isotherms for Intermediates Formed in Charge Transfer Processes
Authors: Gileadi E. 
Published: November 2013

AbstractThe adsorption of phenol in the form of phenoxy radicals on the surface of a bright Pt electrode is discussed. Two main features of the adsorption isotherm are brought out. The fractional coverage Θ changes suddenly at a characteristic potential, in a manner reminiscent of two dimensional phase formation. This is attributed to the existence of an isotherm with strong lateral attraction interaction forces. The corresponding two‐dimensional equation of state resembles qualitatively the Van der Waals equation of state at temperatures below the critical temperature. For the potential dependence of adsorption a new type of isotherm is used which combines the effects of potential on charge‐transfer equilibrium and on the solvent‐solute replacement equilibrium on the surface of the electrode. The resulting function, describing the variation of Θ with E fits the observed inhibition effects of phenol on the rate of oxidation of Γ, and should also be taken into consideration in deriving Tafel slopes for different mechanisms.
Orthonormal Chemical Reactions and Chemical Relaxation Part 4. Reactions in Solution with Concomitant Entropy and Volume Changes
Authors: Hayman H.J.G. 
Published: November 2013

AbstractThe method described previously [2, 3] for obtaining the relaxation times, normal coordinates and normal modes of relaxation of a chemical system is extended to the case in which heat transfer and volume changes occur at rates too slow to maintain isothermal and isobaric conditions. The four types of chemical relaxation treated previously (isothermal and adiabatic relaxation at constant pressure and at constant volume) form limiting cases of this problem whose solution thus provides a generalization and unification of the concept of orthonormal chemical reactions.
Topochemistry. Part XXXII. The Crystal Structures of 9‐Methyl‐, 9‐Methoxycarbonyl‐, and 9‐Methoxyanthracene
Authors: Bart J. C. J. , Schmidt G. M. J. 
Published: November 2013

AbstractThe crystal structures of 9‐methyl‐, 9‐methoxycarbonyl‐, and 9‐methoxyanthracene have been solved by the SEARCH procedure and refined from partial three‐dimensional photographic data to acceptable agreement factors. The molecular shapes are briefly discussed. The packing arrangements of the first two compounds provide for antiparallel juxtaposition across inversion centres of nearest‐neighbour molecules (interplanar distances of 3.57 and 3.39 Å) and C(9) … C(10′) contacts of 3.87 and 3.68 Å. In the non‐centrosymmetric packing of 9‐methoxyanthracene the distances between meso‐carbons of nearest‐neighbour molecules are greater than 4.5 Å.
Mineralogy of Refractory Brick (50% Al2O3) Made from Negev Clays
Authors: Mishirky S. A. , Siniansky W.I. 
Published: November 2013

AbstractThe mineralogy of refractory bricks (50% Al2O3) made under varying conditions of temperature, pressure and grain size was investigated. Maximum temperature attained was 1450°C, pressure was varied between hand pressing and 1000 kg/cm2, grain size ranged from < 0.088 mm to 6 mm and was obtained by varying duration of the grinding process. The bricks produced were subjected to chemical and X‐ray diffraction studies, measurement of physical properties, and optical studies in thin sections. It is concluded that optimum conditions for manufacture of refractory brick are high temperature and pressure. Grain size itself is crucial, but the grinding process is far more efficient if the two starting clay materials are ground together rather than separately. It was concluded that TiO2 served as a mineralizer, and it favors well developed mullite crystal. Cristobalite was not detected at all by optical methods, while it was detected clearly by X‐ray diffraction.
Studies on the Stability of Calcium Chloraluminate
Authors: Ben‐Yair M. 
Published: November 2013

AbstractCalcium chloraluminate (3CaO · Al2O3 · CaCl2 · 10H2O) is a deterioration product of Portland cement found in concrete. It is formed by the attack of chloride solutions on two of the Portland cement components: hydrated calcium aluminate and lime. A study of the synthesis and stability of calcium chloraluminate in different media are described. Calcium chloraluminate enhances the growth of high calcium sulphoaluminate crystals (3CaO · Al2O3 · 3CaSO4 · 31H2O).
Turbidity of the Suspension of Copper Montmorillonite Treated with Methylene‐Blue
Authors: Yariv S. , Lurie D. 
Published: November 2013

AbstractThe influence of methylene‐blue on the turbidity of suspensions of copper montmorillonite at various wavelengths was studied. Methylene‐blue is a coloured molecule and this leads to anomalies in light scattering of the montmorillonite‐methylene‐blue complex. Turbidity changes inversely with particle size.
Bromination of p‐Bromophenol in the Presence of Pyridine
Authors: Somaskandan K. , Sridhar N. , Rajaram J. , Kuriacose J.C. 
Published: November 2013

AbstractThe role of pyridine (Py) in the bromination of p‐bromophenol (ArH) in CCl4 has been investigated. At constant concentrations of ArH and Br2, the rate of disappearance of Br2 increases to reach a limiting value as the concentration of Py is increased. The mechanism suggested to account for the rate expression, Rate = constant [ArH] [Br2]T[Py]T, obtained from the initial rate studies, involves the interaction between ArH and the brominating species Py. Br2, in the rate determining step. Py acts as a catalyst probably by virtue of its ability to polarise the Br‐Br bond.
3,5‐Dihydroxy‐4‐Phenylisoxazole
Authors: Zvilichovsky G. 
Published: November 2013

Abstract3,5‐Dihydroxy‐4‐phenylisoxazole, which is described here, is the first known 3,5‐dihydroxy derivative of isoxazole. Its unusual physical and chemical properties were studied. The tautomeric structures and the methylation products are elucidated.
Interaction Between Montmorillonite and Benzidine in Aqueous Solutions I. Adsorption of Benzidine on Montmorillonite
Authors: Lahav N. , Raziel S. 
Published: November 2013

AbstractAdsorption of benzidine on montmorillonite (bentonite) particles suspended in aqueous solutions was studied by measuring the absorbance of the solution at 280 nm before and after mixing the two reactants. Benzidine adsorption decreased with an increase of suspension pH from 7 to 9.3. NaCl and calgon (Na‐hexametaphosphate) decreased the adsorption, the latter being more effective at the equivalent concentration. The interaction between benzidine and montmorillonite was connected to cation exchange processes and was influenced by the specific adsorption of the metaphosphate ion on the crystal edges.
Initiation and Propagation Steps in the Solid State Polymerization of Vinyl Monomers
Authors: Chapiro Adulphe 
Published: November 2013

AbstractSeveral problems raised by initiation and propagation steps in solid‐state polymerizations are reviewed on the basis of data taken from the literature as well as from unpublished work. The nature of the initial active centers is briefly considered; their addition to double bonds within the crystal is discussed. Examination of initiation yields in radiation‐induced polymerizations shows that the efficiency of chain initiation rises with temperature. In most vinyl monomers, the propagation process, which is severely hindered in the crystal, presumably starts at lattice imperfections and thereafter proceeds on behalf of the additional imperfections introduced by the accumulated polymer. In a few specific cases the orientation of the double bonds in the crystal or their localization in certain regions of the crystal favours chain propagation and may result in a stereocontrolled reaction. The role of crystallite boundaries is emphasized particularly in the case of copolymerizations which take place in eutectic mixtures of two monomers.
The Crystal and Molecular Structure of Ethyl p‐Chloro α‐Cyano‐β‐Methyl‐Cis‐Cinnamate, C13H12No2Cl
Authors: Higuchi T. , Nagai W. , Nakatsu K. , Miwa T. , Shimada A. 
Published: November 2013

AbstractCrystals of ethyl p‐chloro α‐cyano‐β‐methyl‐cis‐cinnamate, C13H12NO2Cl, are orthorhombic, space group Pbcn, with eight molecules per unit cell, a = 17.31, b = 8.68 and c = 17.20 Å. The structure was solved by direct methods and refined subsequently by Fourier techniques. The benzene ring makes a dihedral angle of 60.0° with the ethylenic group. This suggests significant steric effects of the β‐methyl group and of the carbonyl group on the orientation of the benzene ring. The conformation of the ethylene bond and the carbonyl group around the CαC bond is roughly cisoid and the angle of twist is 16.5°. Nearest‐neighbour >C = C <groups make contact across a two‐fold axis at a center‐to‐center distance of 4.33 Å.
Evolution of a Space Charge Limited Current Regime in Organic Crystals
Authors: Pope Martin , Kallmann Hartmut 
Published: November 2013

AbstractRecently published data dealing with interactions of triplet excitons with trapped holes and trapped electrons in anthracene are interpreted in accordance with well‐known but often neglected concepts of the evolution of a space charge limited current (SCLC) in insulators. Discrete, closely spaced trapping levels are delineated, and it is proposed that SCLC do not commence in some crystals until the applied voltage exceeds 2000 V. It is suggested that dimer clusters act as trapping sites.
Distortion of Excited Molecules in Organic Solids
Authors: Hochstrasser Robin M. , Wiersma Douwe A. 
Published: November 2013

AbstractIn this paper we present some ideas concerning the role of the crystal field in stabilizing dynamically distorted electronic states of aromatics. It is shown that a crystal field term of appropriate symmetry reveals in a dramatic way the result of strong vibronic coupling in emission spectra. Conditions under which these distortions are bound to occur are discussed with an emphasis on qualitative understanding. In this context the role of predissociating modes in spectra of aromatics is touched upon and the ideas are demonstrated through discussions of the emission spectra of pyrazine, p‐dibromobenzene and m‐dichloropyrazine.
The Crystal and Molecular Structures of the Centrosymmetric Hexa‐o‐Phenylene
Authors: Irngartinger Hermann 
Published: November 2013

AbstractThe crystal structure of the centrosymmetric isomer of hexa‐o‐phenylene has been solved by direct methods from counter data collected with MoKα radiation on a computer‐controlled diffractometer by the balanced‐filter technique and has been refined to R = 0.046. The deviation of the observed structure from an idealized regular geometry is assigned to intra‐ and intermolecular repulsions. The length of the bond linking the benzene rings is 1.498 Å, the angle of twist between the planes of the benzene rings is 77.4°. The packing arrangement shows a pseudo‐trigonal pattern.
Potentiometric Microdetermination of Boron in Industrial Brines and in Concentrated Salt Solutions
Authors: Scher Aharon , Cogan Edward 
Published: November 2013

AbstractAs little as 0.1 mg boron (1 mg/liter) may be determined in salt solutions containing as much as 400 g/liter MgCl2, MgBr2, NaCl, KCl and CaCl2 or in analytical reagent grade salts with an accuracy of 2% relative. The lower monovalent alcohols do not interfere. The two equivalent points, the gap between them and the role of ionic strength are discussed.
Kinetics of HCl Uptake by Macroporous Weak‐Base Anion Exchangers
Authors: Oke R. B. , Millar J. R. 
Published: November 2013

AbstractThe kinetics of uptake at 25° of 0.01 N HCl by dimethylamine‐aminated macroporous resins depend in a complex manner on the porosity of the resin. While pure C‐ and P‐kinetics are observed respectively at the nonporous and highly macroporous ends of the porosity scale, under the experimental conditions employed the diffusional and chemical fluxes are similar in magnitude, and either pseudo‐P or pseudo‐C kinetics may be shown at intermediate porosity levels, of which three examples have been examined.
Some Biochemical Processes Induced by Radiation as Studied by Pulse Radiolysis
Authors: Swallow A. J. 
Published: November 2013

AbstractThe main types of biochemically important electron transfer substances can be made to undergo reactions under irradiation which in some ways mimic those which occur in nature. In the case of NAD+, pulse radiolysis shows that electrons add to the pyridine ring forming an NAD· radical with a characteristic absorption in the visible range which is capable of transferring its electron to oxygen. Using simpler pyridinyl compounds it has been found that, as well as the absorptions in the visible range, the radicals exhibit absorptions in the infrared range which correlate well with transitions which may be deduced from the known charge‐transfer bands of the parent compound. The NAD· radical can be made by one‐electron oxidation of NADH as well as by reduction of NAD+, and the reaction with oxygen enables NADH to be converted into NAD+ by an unambiguous free radical route. Cytochrome‐c can be reduced either by hydrated electrons or CO2−. In solution buffered to neutral pH, the reduction gives rise immediately to normal reduced cytochrome‐c, but in mildly alkaline solution, an unstable reduced form appears whose conformation changes over a fraction of a second to that of normal reduced cytochrome‐c. As well as the hydrated electron and CO2−, the superoxide anion radical O2− has also been found to reduce cytochrome‐c. This reaction is very slow (k ∼ 105 M−1 sec−1).
Radiolysis of Ribonuclease in Controlled Environments
Authors: Adelstein S. J. , Mee L. K. , Stein G. 
Published: November 2013

AbstractThe separate contributions of the primary aqueous radicals to the changes in activity, molecular configuration and amino acid composition of RNase, produced by γ‐irradiation of dilute solutions, have been identified. The most effective radical for inactivation is the H atom. Additional molecular products are formed on irradiation of the enzyme. Amino acid analyses of the irradiation products show significant damage only to the aromatic and sulfur‐containing residues.
Pulse Radiolysis and Inactivation of Trypsin
Authors: Ovadia Jaques 
Published: November 2013

AbstractA study of the mechanism of aqueous trypsin inactivation by radiation was carried out by pulse radiolysis and steady irradiation in the presence of various scavengers. The initial products consist of OH radical and H atom adducts to tryptophan residues, and of electron adduct to cystine residues. Essentially, all OH react with trypophan with k(OH + trypsin) = (8.2 ± 1.2) × 1010 M−1 sec−1. The electron adduct to the disulphide bond accounts for about 60 per cent of the electron yield, with k(eaq + trypsin) = (3.5 ± 0.8) × 1010 M−1 sec−1. Measurements of tryptophan residue loss and sulphydryl formation under different irradiation conditions show that the initial reactions are substantially reversible, except for the destruction of tryptophan under aerobic conditions. Many primary radicals induce inactivation with low independent probabilities, indicating that only a small fraction of the possible reaction sites for each species influence the integrity of the active center.
Factors which Influence the Sedimentation Properties of Mammalian Cell DNA: Effect of Two‐Dose X‐Irradiation
Authors: Belli James A. , Nagle William 
Published: November 2013

AbstractThe sedimentation behavior of DNA extracted from mammalian cells was studied after fractionated irradiation. Our results show that the injury registered by a second X‐ray dose is not additive to that registered by the first, and that DNA, having repaired its initial radiation damage, is less susceptible to a subsequent irradiation. The following hypothesis is suggested. Repair processes of DNA begin with unmasking of “initiation sites” and that, in time, these become associated with membrane material within the nucleus.
Kinetics of Film Diffusion Controlled Ion Exchange Processes, Theory and Applications
Authors: Bunzl K. 
Published: November 2013

AbstractA differential equation describing the kinetics of film diffusion controlled ion exchange processes is derived on the basis of the theory of irreversible thermodynamics. This equation is solved subsequently with the boundary conditions of infinite solution volume and applied to some experimental results involving differential ion exchange reactions. In case of the boundary conditions of a finite solution volume, the kinetics of dissolution of a sparingly soluble salt by an ion exchanger is considered.
Ammonium Chloride Separated into Ammonia and Hydrogen Chloride, with the Aid of Metal Oxides
Authors: Ashboren (Araten) David 
Published: November 2013

AbstractThe two‐stage decomposition of ammonium chloride into ammonia and hydrogen chloride, with the aid of metal oxides, was investigated. Twenty‐one oxides were considered for this sequence, and 14 were actually tested and the temperature range of the reactions determined. The energy requirements for heating the metal chlorides from t1 to t2 were calculated. For Fe2 O3, the temperatures are 200° and 300°, respectively, and the heating requirement ca. 17 × 103 kcal/t NH4Cl converted.
Anionic Graft Polymerization of Lauryl Methacrylate on Starch
Authors: Cohen Eliahu , Zilkha Albert 
Published: November 2013

AbstractThe anionic graft polymerization of lauryl methacrylate on the potassium alkoxide derivative of starch was studied. The yield of graft polymer increased with increasing alkoxide concentration. With increasing monomer concentration and with increasing temperature, the extent of homopolymer formation increased. The composition of the graft polymers depends on the reaction conditions; graft polymers having about 30–65% polylauryl methacrylate were obtained.
Adsorption of Heavy Metal Salts by Cotton Fabrics Containing Polyethylene and Polypropylene Sulfide
Authors: Avny Yair , Leonov David , Zilkha Albert 
Published: November 2013

AbstractThe adsorption of mercury and other heavy metal salts by cotton fabrics containing polyethylene and polypropylene sulfide was investigated. Adsorption of mercuric chloride from aqueous solution was investigated in detail, and AH of the reaction was determined. A general screening of the capacity of adsorption of the polymers for heavy metal salts was carried out. Differences in behavior between the polymeric system and simple thioethers were observed. Auric, antimony, titanium, palladium, platinum and bismuth salts were adsorbed by the modified cotton; other salts, known also to complex with organic sulfides, were not adsorbed.
Solid‐Gas Reactions, Part III. Interaction of Solid Dibenzoylethylenes with Bromine and Iodine Vapours
Authors: Hadjoudis E. 
Published: November 2013

AbstractThe cis and trans isomers of solid 1,2‐dibenzoylethylene, 1,2‐di‐p‐chlorobenzoylethylene and 1,2‐di‐p‐methyl‐benzoylethylene yield, on exposure to bromine vapour at room temperature, the trans‐adducts in quantitative yield except in the case of cis‐1,2‐di‐p‐methyl‐benzoylethylene where isomerisation takes place prior to or during the bromination process yielding the same dibromide as the trans‐isomer. The cis‐trans isomerisation of the three solid cis‐isomers by iodine vapour has been analysed by determining the rate of the reaction from the change in IR transmittance. The isomerisation follows a first‐order mechanism. A plot of ΔH++ against ΔS++ is linear.
Conductance of Polyelectrolyte Solutions: A One—Dimensional Model
Authors: Lifson Shneior 
Published: November 2013

AbstractAn exact derivation of the conductance of parallel double‐layers as a one‐dimensional model of polyelectrolyte solutions is presented. The conductance tends to a finite limit, inversely proportional to the square of the (one‐dimensional) polyelectrolyte concentration, as the polyelectrolyte charge density increases indefinitely. In other words, the conductance tends to zero with the square of the inverse polyelectrolyte concentration in a way independent of the polyelectrolyte charge density. Approaching these limits, the ionic mobility of the counterions predominates over that of the fixed charges. The assumption of superposition of the external and internal electrostatic fields is shown to be inexact even at the limit of very small external fields.
Dichlorocarbene Chlorination of Steroids
Authors: Ikan R. , Markus A. , Goldschmidt Z. 
Published: November 2013

AbstractDichlorocarbene, generated from chloroform, aqueous sodium hydroxide and catalytic amount of triethylbenzylammonium chloride, reacts readily with steroids (5α‐stigmastan‐3β‐ol, 5α‐lanost‐8(9)‐en‐3β‐ol‐17‐one and estrone) leading to the corresponding chlorides in fair yields.
Calcium Oxalate Crystallization from Inhibited Solutions
Authors: Sarig Sara , Raphael Micha , Ron Amos 
Published: November 2013

AbstractThe induction periods of calcium oxalate precipitation at high supersaturations were measured and the degrees of inhibition in the presence of different trace quantities of polyphosphates were determined. Crystals were grown from uninhibited and from partially inhibited solutions. The presence of both polyphosphates and of cationic impurities affects the crystal habit very strongly: rod‐like crystals up to 3 mm in length grew from inhibited solutions in a week, whereas very small round particles of 10−2 mm size sprang from the uninhibited solutions. Some previously published mechanisms are reviewed, and a new, comprehensive, heterogeneous nucleation mechanism of growth is proposed to explain the simultaneous inhibition of precipitation and inducement to growth of large crystals.
The Triple Complexes of Copper and its Complexes with the Schiff Bases of Pyridine‐2‐Aldehyde or 2‐Acetyl Pyridine with Aliphatic Diamines
Authors: Kirson B. 
Published: November 2013

AbstractWhen alcohol solutions of copper salts are mixed with pyridine‐2‐aldehyde (PyA) and aliphatic diamines (A) (either ethylene diamine or 1,3‐propane diamine) at pH ≤ 6.5, a copper complex containing a molecule of the pyridine derivative and a molecule of the diamine is formed, or a complex containing an additional molecule of the pyridine aldehyde is formed, depending on the PyA concentration in the solution. When the molar concentrations are Cu2+: 2PyA: A, and the pH ≥ 10, the copper (II) ion is reduced to monovalent copper, and a Schiff base of the copper complex is formed. When alcoholic solutions of copper, 2‐acetylpyridine (AcPy), and aliphatic diamines are mixed in concentration ratios of Cu2+: 2AcPy: A, and pH > 9.5, again, the copper ion is reduced and a Schiff base is obtained. At pH = 7.5 a triple complex is obtained only from the copper chloride, containing either or one or two molecules of acetylpyridine, depending on the concentration of the latter in the solution.
Planar and Nonplanar Unsaturation. Preparation, Properties and Molecular‐Orbital Characterization of Some Fluoro‐Derivatives of Anthracene and Anthraquinone
Authors: Meyer A. Y. , Goldblum A. 
Published: November 2013

AbstractSeveral fluoroanthracenes (I‐III) and fluoroanthraquinones (IV‐VII) were prepared, and their PMR and UV spectra, as well as dipole moments, recorded. These are discussed in terms of molecular‐orbital data, both of the pi‐electronic type (including nonbonding 2p‐orbitals) and of the all‐valence‐electron type. PMR signals can be assigned on the basis of such calculations. The interpretation of UV spectra is straightforward in the case of fluoroanthracenes, but other techniques are required for fluoroanthraquinones. Measured dipole moments are close to the theoretical, except in the case of 1, 4, 5, 8‐tetrafluoroanthraquinone. A distorted structure is proposed for this molecule.