bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the Diradicaloid Character in a Prototypical Pancake‐Bonded Dimer: The Stacked Tetracyanoethylene (TCNE) Anion Dimer and the Neutral K2TCNE2 Complex
Authors: Cui Zhong‐hua , Lischka Hans , Mueller Thomas , Plasser Felix , Kertesz Miklos
Published: November 2013

The π‐bonded tetracyanoethylene anion dimer (TCNE22−) and the neutral K2TCNE2 system have been investigated to obtain new insights into the unique features of two‐electron multicenter (2e–mc) π‐pancake bonding. The inter‐radical interaction leads to a significant diradicaloid character described by two singly occupied molecular orbitals (SOMOs) of the monomers. A highly correlated approach, the multireference averaged quadratic coupled‐cluster (MR‐AQCC) method, has been used to achieve a balanced description of the different types of electron correlation that occur in this system. The analysis of the interaction energies for the two systems in the singlet and the lowest triplet states and of the unpaired electron densities demonstrate the importance of diradical π bonding in addition to the conventional van der Waals interactions that occur in intermolecular interactions. In this analysis, the separation of the repulsive Coulomb interaction energies from the remaining terms turned out to be a crucial prerequisite to achieve consistent results. Our calculations also confirm that the driving force behind the energetic stability of the pancake bonds predominantly derives from the overlap of the SOMO–SOMO bonding interaction.
Handoff optimization and load balancing in wireless LANs using association control
Authors: Sun Quan , Huang Liusheng , Zhang Haoran , Xu Hongli
Published: November 2013

As users move around in wireless local area networks, they associate with different access points in succession to maintain connectivity. Without the carefully designed association control policy, it may lead to frequent handoffs and imbalanced load, which can potentially incur unacceptable delays and poor throughput. While existing works to this issue mainly focus on minimizing the number of handoffs over time, in this paper, we propose a new association control scheme with the goal of reducing the frequency of handoffs and balancing load among access points. The defined problem, handoff optimization and load balancing (HOLB,) is mathematically described as a minimum–maximum programming. Since the HOLB problem is a nondeterministic polynomial‐time hard, two constant approximation algorithms are presented to resolve it. First, we propose an α‐approximation() centralized algorithm CHOLB. CHOLB employs a novel method to simplify the original problem to the minimum‐cost maximum‐flow problem, which is solved in polynomial time. On the sis of CHOLB, we then put forward a β‐approximation () distributed algorithm DHOLB for the purpose of scalability and lightweight. DHOLB partitions the network into clusters and uses CHOLB as its local centralized algorithm within each cluster. Extensive evaluations show that the proposed algorithms outperform the existing schemes in terms of the handoff frequency and traffic load. Copyright © 2013 John Wiley & Sons, Ltd.
PPARgamma agonist pioglitazone does not enhance performance in mice
Authors: Sanchis‐Gomar Fabian , Pareja‐Galeano Helios , Martinez‐Bello Vladimir E.
Published: November 2013

Peroxisome‐proliferator‐activated receptor (PPAR) delta and adenosine monophosphate (AMP)‐activated protein kinases (AMPKs) regulate the metabolic and contractile characteristics of myofibres. PPAR proteins are nuclear receptors that function as transcription factors and regulate the expression of multiple genes. AMPK has been described as a master metabolic regulator which also controls gene expression through the direct phosphorylation of some nuclear proteins. Since it was discovered that both PPARdelta agonists (GW1516) and AMPK activators (5‐aminoimidazole‐4‐carboxamide‐1‐β‐D‐ribofuranoside, known as AICAR) are very effective performance‐enhancing substances in sedentary mice, the World Anti‐doping Agency (WADA) included AICAR and GW1516 in the prohibited list of substances as metabolic modulators in the class ‘Hormone and metabolic modulators’. Thiazolidinediones are PPARgamma agonists that can induce similar biological effects to those of PPARdelta and PPARdelta‐AMPK agonists. Thus in this study, the effects of pioglitazone on mitochondrial biogenesis and performance were evaluated. Blood glucose levels and the protein expression of the intermediates involved in the mitochondrial biogenesis pathway and the citrate synthase activity were determined in both gastrocnemius and soleus muscles. Maximal aerobic velocity (MAV), endurance capacity, and grip strength before and after the training period were also determined. The MAV endurance capacity and grip strength of trained animals significantly increased. We found that the peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α) and the nuclear respiratory factor‐1 (NRF‐1) protein content and citrate synthase activity significantly increased in the soleus muscle of trained animals. No effect of treatment was found. Therefore in our study, pioglitazone administration did not affect mitochondrial biogenesis signaling pathway. Copyright © 2013 John Wiley & Sons, Ltd.
The Challenge of Environmental Governance In The Network Society: The Case of The Baltic Sea
Authors: Tynkkynen Nina
Published: November 2013

The Baltic Sea region has in recent years become known as a pioneer of new modes of governance, reflecting the dynamic development of the network society. At the same time, the Baltic Sea is considered one of the world's most polluted seas, especially in terms of eutrophication, the accelerated enrichment of nutrients in the water. Overall, there is a contrast between the formally successful governance system and the actual state of the Baltic Sea. This paper describes the existing Baltic Sea environmental governance system, from the regional regime to non‐governmental actors, noting that highly institutionalized inter‐state and transnational environmental cooperation adds a greater element of hierarchy for environmental governance in the region. Supporting democratic development is a special requirement for governance in the post‐Cold War context. The paper explicates governance challenges posed by the emerging network society, on the one hand, and the problem of eutrophication, on the other, and makes suggestions on how to develop the governance system in order to meet the challenges. As a conclusion, a general lesson for the management of international water bodies is given. Institutional diversity with many different scale preoccupations is key, but so is the need for leaders to overcome the challenges of polycentric governance: that is, to reduce opacity of governing and to increase the power of stakeholders to define the problem and its solutions in the first place. Copyright © 2013 John Wiley & Sons, Ltd and ERP Environment.
Responsible Procurement, Complex Product Chains and the Integration of Vertical and Horizontal Governance
Authors: Boström Magnus , Karlsson Mikael
Published: November 2013

The management of environmental and health risks associated with products from global product chains is a pressing task for contemporary society, a task that involves public and private actors and poses great governance challenges. This article explores how governance arrangements relate to these challenges by focusing on how public and private procuring organizations interpret, use, develop and combine mandatory and voluntary policy instruments. This is theorized in terms of responsible governance of transnational supply chains (RGSC) as well as regarding the combination of vertical and horizontal governance (VG and HG). The article focuses on chemical risks in the textile sector, and is based on findings from case studies of Swedish public and private procuring organizations, with additional interviews with actors engaged in developing various policy instruments. The article shows how mandatory and voluntary policy instruments can – in various ways and combinations – assist in chemical risk management, but also highlights the existence of considerable limitations and gaps, which users need to develop a reflective awareness about. The article reveals different conditions for public and private procurers, and the conclusion includes suggestions on how to bridge the gap between private and public actors. Finally, we conclude by emphasizing that combinations of HG and VG arrangements promote constructive and feasible pathways towards RGSC, but which needs reflective and constructive efforts among actors with insight, willingness and capabilities to create governance linkages. Copyright © 2013 John Wiley & Sons, Ltd and ERP Environment.
Investigation of oxidative degradation and non‐enzymatic browning reactions in krill and fish oils
Authors: Thomsen Birgitte Raagaard , Haugsgjerd Bjørn Ole , Griinari Mikko , Lu Henna Fu Sieng , Bruheim Inge , Vogt Gjermund , Oterhals Åge , Jacobsen Charlotte
Published: November 2013

The aim of this research was to investigate the oxidation progress and pathways of krill and fish oil during 21 days of incubation at 40°C. The oxidative stability of the oils was investigated through: (i) classical methods such as peroxide value (PV), anisidine value (AV), thiobarbituric reactive substance (TBARS), conjugated dienes and trienes, and antioxidant content, and (ii) advanced methods such as determination of volatiles content by dynamic headspace (DHS)‐GC/MS, lipid classes, and pyrrole content. In addition, the oxidative stability of the oils was evaluated under accelerated oxidation conditions using the Oxipres™ at 90°C. The results from analysis of PV, AV, TBARS, conjugated dienes and trienes, and the antioxidant content suggested that krill oil was more oxidatively stable than fish oil. However, the color or other constituents of the krill oil might affect the result of these classical methods. Nevertheless, the conclusion was supported by the results of the Oxipres™ measurements, which showed that the oxygen consumption was higher for fish oil. Furthermore, the level of most volatile lipid oxidation products was higher for fish oil. The development of Strecker degradation products and pyrroles formed as a result of non‐enzymatic browning reactions could only be observed in krill oil. The presence of pyrroles might have contributed to the higher oxidative stability of krill oil. Krill oil also contained a higher level of tocopherol, astaxanthin and phospholipids than fish oil, which could have resulted in better protection against oxidation. The results demonstrated that the classical methods for measuring oxidative deterioration of lipids were not useful for krill oil.
Recent advances in miniaturization—The role of microchip electrophoresis in clinical analysis
Authors: Guihen Elizabeth
Published: November 2013

This review is a follow‐up from the last review published in 2012 that covers the same topic [22]. Its aim is to cover new innovations and developments since then, involving the role of microchip capillary electrophoresis (MCE) in clinical analysis. MCE has shown great promise in separation science, as it's a state‐of‐the‐art analytical separation technique that offers speed, portability, reduced sample, and reagent requirements, repeatability, can be used online or offline, and can be coupled with many kinds of analytical detectors. It is particularly important in clinical analysis, as it offers online continuous monitoring, can handle small volumes of highly complex biological samples due to its powerful discriminating ability, and it facilitates point‐of‐care testing. Also microchip separation platforms have been used for sample clean‐up, filtration, derivatization, separation and detection, acting as multifunctional platforms ideal for minute sample volumes. In recent times the clinical world has witnessed a need for rapid turnaround times on analysis of very complex samples, and so there has been a shift toward point‐of‐care testing and other miniaturized analytical techniques as a favorable solution. Research developments in this area have been catalyzed by rapid strides in knowledge in the areas of proteomics, metabolomics, and molecular biology in the quest to understand the physiology of cells, proteins, genes, molecular interactions, and the pathophysiology of disease. Herein, we present selected examples detailing the use of MCE in some of the latest and most exciting clinical applications.
ITP of lanthanides in microfluidic PMMA chip
Authors: Cong Yongzheng , Bottenus Danny , Liu Bingwen , Clark Sue B. , Ivory Cornelius F.
Published: November 2013

An ITP separation of eight lanthanides on a serpentine PMMA microchip with a tee junction and a 230‐mm‐long serpentine channel is described. The cover of the PMMA chip is 175 μm thick so that a C4D in microchip mode can be used to detect the lanthanides as they migrate through the microchannel. Acetate and α‐hydroxyisobutyric acid are used as complexing agents to increase the electrophoretic mobility difference between the lanthanides. Eight lanthanides are concentrated within ∼ 6 min by ITP in the microchip using 10 mM ammonium acetate at pH 4.5 as the leading electrolyte and 10 mM acetic acid at ∼ pH 3.0 as the terminating electrolyte. In addition, a 2D numerical simulation of the lanthanides undergoing ITP in the microchip is compared with experimental results using COMSOL Multiphysics v4.3a.
Fullerene as a transporter for doxorubicin investigated by analytical methods and in vivo imaging
Authors: Blazkova Iva , Viet Nguyen Hoai , Kominkova Marketa , Konecna Romana , Chudobova Dagmar , Krejcova Ludmila , Kopel Pavel , Hynek David , Zitka Ondrej , Beklova Miroslava , Adam Vojtech , Kizek Rene
Published: November 2013

Carbon nanomaterials, including fullerenes, exhibit not only unique structure and electronic properties but also a significant potential to serve as radical scavengers and/or anti‐oxidants. Their conjugation with anticancer drugs such as doxorubicin (DOX) may help to balance severe negative side effects of these cytostatics and also improve the delivery of the drug taking advantage of the enhanced cellular uptake, selectivity to cancer cells, and pH regulated release. In this study, the fullerene (C60) surface was oxidized by concentrated nitric acid, which enabled simple DOX–fullerene conjugation based on π–π stacking and hydrophilic interactions with carboxylic groups. The strength of this noncovalent binding is pH dependent. At a low pH, the amino group of DOX is protonated, however at a higher pH, the amino group is deprotonated, resulting in stronger hydrophobic interactions with the fullerene walls. CE and HPLC were employed for characterization of resulting complexes. The cell toxicity of the conjugates was evaluated using Staphylococcus aureus and finally they were administered into the chicken embryo to assess the applicability for in vivo imaging.
Michael Reaction with Nitroform and Related Syntheses
Authors: Strumza J. , Altschuler Shaloma
Published: November 2013

Michael reactions have been carried out between nitroform (trinitromethane) and fourteen acceptors; the reactions do not require external catalysts.

Of special practical interest are the Michael adducts of the acrylates of nitroalcohols and nitrodiols.

1,2‐Dibenzoylethyleneand 1,4‐naphthoquinone add nitroform normally, but the adducts spontaneously lose nitrous acid, so that formally dinitromethyl substitution takes place. Mononitroalkanes add normally to these two 2,3‐unsaturated 1,4‐diketones.
The Determination of Microgram Quantities of Indium in High Purity Uranium
Authors: Schoenfeld Irena
Published: November 2013

Microgram quantities of indium were separated from uranium by ion exchange as an anionic complex in hydrochloric acid. The completeness of the separation was established using In114 as tracer. Indium in the water eluate was determined spectrographically by DC‐arc excitation. The coefficient of variation for a single determination is about 25%;the absolute limit of detection 0.01μg of indium.
Kinetic Studies on the Methylation of Thiopurines
Authors: Bergmann F. , Kleiner M.
Published: November 2013

Both 6‐mercaptopurine and 6‐thioxanthine, when treated with methyl iodide in dimethylformamide, undergo a two‐step reaction, i.e. first methylation at the sulphur atom, followed by alkylation at N‐3. Reaction; at the sulphur atom of 3‐methyl‐6‐purinethione proceeds 1350 times faster than in 6‐mercaptopurine.
Synthesis of Compounds Related to Steroids. Reactions of β‐Methyltricarballylic Acid Anhydride with Benzene and Naphthalene
Authors: Harnik M.
Published: November 2013

β‐Methyltricarballylic acid anhydride (I) undergoes an efficient three‐step reaction sequence whereby it is transformed into known intermediates useful in the synthesis of aromatic steroids. Experiments are described in the benzene series leading to the preparation of the tetralone derivative (VIIa), and in the naphthalene series giving the tetrahydrophenanthrene acids (XV) and (XIII).
The Synthesis of Some Mercurial Derivatives of Simple Sugars
Authors: Leftin J. H. , Lichtin N. N.
Published: November 2013

A number of organomercurials have been produced by oxymercuration of 3,4,6‐tri‐O‐acetyl‐D‐glucal and 2,3,4,6‐tetra‐O‐acetyl‐2‐hydroxy‐D‐glucal followed by replacement of mercury‐bound acetate with a variety of ions. Data collected in connection with investigating the structure of one of the products suggest that reductive demercuration by NaBH4 may proceed with retention of configuration of the mercury‐bound carbon atom.
Total Synthesis of 3,6‐Dimethoxy‐17β‐Acetyl‐1,3,5(10),6,8‐Estrapentaene
Authors: Harnik M. , Jensen E. V.
Published: November 2013

A Friedel‐Crafts reaction of 2,8‐dimethoxynaphthalene with β‐methyltricarballylic acid anhydride (I) gave the ketoacid (IId), which upon catalytic hydrogenation and cyclization with hydrogen fluoride afforded the tricyclic ketone (V). Addition of methyl acrylate yielded the tetracyclic ester (VI), which was dehydrated and then decarboxylated at carbon 15. The reactions could be controlled to produce either the 17α‐ or the 17β epimers (IX) and (X). Their hydrogenation furnished the 14β, 17α‐ and 14α, 17β isomers (XII) and (XIb), respectively. The latter was transformed into the 17β‐acetyl derivative (XIe).
Kinetics of the Nucleophilic Substitution Reaction Between 2,4‐Dinitrochlorobenzene and Azide Ions
Authors: Patai S. , Gotshal Y.
Published: November 2013

The reaction between azide ions and 2,4‐dinitrochlorobenzene was found to be of first order in each of the reactants. The reaction is slower in more polar media, and is completely inhibited by acid. The place of azide ions in the nucleophilicity order of aromatic substituting agents is assigned.
On the Nature of the Cation‐Insensitive Bonds of Myelin
Authors: Wolman M. , Wiener H. , Bubis J.J.
Published: November 2013

Half the lipids of myelin which belong to the cation‐insensitive complexes (i. e. 25% of the total lipids) are sensitive to anions and can be extracted by water after treatment with KCNS or Kl. Thin layer chromatography findings indicate that the cation‐insensitive complexes do not differ in lipid‐composition from the cation‐sensitive complexes. Histochemical findings indicate that the highly lyotropic anions inhibit the same enzymatic activities as the feebly lyotropic cation Ca.

The implications of these findings on the structure of myelin and of cell membranes is discussed. The data are considered to fit best the concept of a plasma membrane in which one surface contains mainly anionic fixed groups and the other surface cationic groups.
Effect of Sugars on the Stimulus‐Response‐Recovery Cycle
Authors: Dikstein S. , Hamburger A. D. , Tal E. , Sulman F. G.
Published: November 2013

(Some, but not all, monosaccharides evoke a “Stimulus” which elicits, a. melanophore reaction; b. contraction of the normal rat ileal smooth muscle and c. contraction of the potassium depolarised rat ileal smooth muscle. Oleate, palmitate. aspartate, glutamate and Krebs cycle intermediates are not stimulants. We propose a working hypothesis, according to which the stimulatory effect of sugars mediates an increased supply of ADP, whilst simultaneously decreasing the glycolysis and thus the supply of cell membrane NADH.
The Direct Determination of Copper and Lead in the HCl Soluble Fraction of Carbonate Rocks
Authors: Yaalon D. H. , Avinur P. , Lipetz‐Herman V. , Barzily I.
Published: November 2013

The U. V. spectra of the chloro‐complexes of copper (I) and lead (II) were studied in various concentrations of calcium and magnesium chloride. Algebraic formulae were developed for the simultaneous and direct determination of trace amounts of copper and lead in the HCl soluble fraction of carbonate rocks. Interference due to background absorbance was reduced by the use of these formulae.
A New Organic Reagent for the Specific Determination of Vanadic Acid
Authors: Ben‐Dor L. , Jungreis E. , Jungreis C.
Published: November 2013

The Schiff base formed from salicylaldehyde and anthranilic acid has been found to be a specific and sensitive reagent for the spectrophotometric determination of vanadium (V). This reagent forms a violet ester with vanadic acid (at pH = 1) extractable with benzene. The determination can be carried out in the presence of many diverse ions, and all but ferric ions do not interfere. Phosphoric acid is used both for masking the iron III and to make the extraction easier. The limit of identification is 10 μg vanadate/1 ml.
Gravimetric Determination of Gold in Alloys
Authors: Avinur P.
Published: November 2013

A method is presented for the gravimetric determination of gold in alloys. Based on a known procedure used in metallurgy, it involves the separation of gold from the other elements constituting the alloy, by the aid of the “parting process”, suitably modified. It involves a relatively simple technique with a high degree of accuracy. Gold was successfully determined in the presence of the following metals: Ag, Cd, Cu, Cr, Fe, Mn, Ni, Pd, Sn, Zn.

Platinum seriously interferes with the analysis.
6‐Trifluoromethyltryptamines
Authors: Kalir A. , Pelah Z. , Balderman D.
Published: November 2013

A series of 6‐trifluoromethyltryptamines has been prepared from 6‐trifluoromethylindole as the starting material. Conversion of the CF3 group to CH3 was observed during the reduction of some of these compounds with lithium aluminum hydride.
Turbidimetric Assay for Pectinase Activity
Authors: Avigad G. , Milner Y.
Published: November 2013

A simple procedure for the estimation of polygalacturonic acid and polymethyl‐galacturonic acid hydrolases is described. The method is based on measuring the residual turbidity formed by complexing the acid polysaccharide with quaternary‐ammonium detergents such as cetyl pyridinium bromide. The assay is carried out at pH 4.5 to 5.0 which is optimal for the hydrolase activities.
The Reactions of Aliphatic Aldehydes with Benzamide
Authors: Giger R. , Ben‐Ishai D.
Published: November 2013

Isobutyraldehyde, propionaldehyde and acetaldehyde have been found to react with benzamide in the presence of napthalenesulfonic acid to give an enamide, two dimeric enamides and a probably polymeric mixture, respectively. The same products were also obtained from the corresponding alkylidenebisbenzamides (I) under acidic conditions.
The Reaction of N‐Bromoacetamide with α, β‐Unsaturated Carbonyl Compounds. Part II
Authors: Bien S. , Ber M.
Published: November 2013

Transformation of some chalcone bromohydrins and their acetates under different conditions are described.
The Effect of Sodium Chloride on Catechol Oxidase from Apples
Authors: Sharon Miriam , Mayer A. M.
Published: November 2013

Catechol oxidase from apple chloroplasts and browning of apple slices are strongly inhibited by the chloride anion. The inhibition is non‐competitive and reversible. Inhibition is pH‐dependent. being observed at pH 5.1 but not at pH 7.3. Activity could be extracted from the particles using CTAB. The extract's activity at the two pH could not be resolved into distinct fractions. The pH‐dependence of inhibition is ascribed to a change in the tertiary structure of the enzyme.
Direct Spectrophotometric Determination of Gold in Alloys as Chloroaurate
Authors: Avinur P.
Published: November 2013

A method is presented for a simple and direct determination of gold in alloys, utilizing a preliminary separation of gold from an alloy, and its subsequent conversion to chloroauric acid.

The optical density of the chloroaurate ion is measured at two selected wavelengths, calculating the gold content of alloys by using the absorbance difference technique as developed by Glasner and Avinur. A suitable technique enables wide‐range determination in various samples of gold alloys ranging from 0.001% to over 90% gold content. Platinum does not interfere when present in small amounts in the alloy.
The Mixed Compounds of Calcium and Titanium With Tiron. I
Authors: Barzily I. , Yaalon D. H. , Avinur P.
Published: November 2013

A pH‐spectrophotometric study of the Ti‐tiron complex in the presence of Ca ions revealed the existence of mixed compounds of Ca‐Ti‐tiron. These could account for the interference of Ca in the determination of Ti by tiron. The formation of these mixed compounds under varying concentrations of components and at varying pH is discussed. The absorbance of the Ti‐tiron was likewise studied in the presence of many colorless salt solutions, but the behavior of Ca was found to be unique. Use was made of the color of the mixed compounds of Ca‐Ti‐tiron to develop a method for the identification of small amounts of Ca in the presence of large quantities of many common salts.
Flash Photolysis of Hydrogen Peroxide I: The Reaction of Ozonide with Hydrogen Peroxide
Authors: Behar D. , Czapski G.
Published: November 2013

The photochemistry of basic aqueous solutions containing hydrogen peroxide and oxygen has been investigated by the flash photolysis method. The decay of O3− was followed at 4300 Å over the pH range 13 – 13.7 as a function of hydrogen peroxide and oxygen concentrations. The decay was found to be of the first order under all conditions −[d(O3)−/dt] = kobs[O3−]. The pseudo first‐order rate constant kobs was found to be dependent on H2O2 and O2 concentrations. A mechanism which is consistent with the experimental results is suggested.
Scavenging Kinetics in the Photochemistry of Some Ions in Aqueous Solution
Authors: Czapski G. , Ottolenghi M.
Published: November 2013

Geminate recombination has been previously suggested in the photochemistry of several ions in solution, namely, the halides, phenolate ferrocyanide and thiocyanate. It is demonstrated that in the concentration range studied, the observed dependence of the quantum yield on scavenger concentrations is due to homogeneous competition between the scavenger and a product or rational intermediates, rather than to cage scavenging competing with geminate recombination.
On the Synthesis and Spectral Properties of Iron‐ Cyanoferrates
Authors: Ben‐Bassat A. H. I.
Published: November 2013

A new procedure for the synthesis of Prussian Green, using HNO3 or dioxane media, is proposed. Synthesis from aqueous H3Fe(CN)6 is described. I.R. spectra of solids and of colloidal suspensions of Prussian Brown, Prussian Green and Prussian Blue are recorded and discussed. An explanation for the 1960 cm−1 vibration stretching is proposed. The identity between Prussian and Turnbull Blue is questioned owing to I.R. results. A mechanism is proposed for the suggested oxyreduction reaction, based on analytical and mass spectroscopy data. Protonation of the complexed iron plays an important role in these reactions. Explanations for contradictory properties and Mössbauer results cited in literature are given.
Heterometric Titration of Sodium Montmorillonite with Calcium Nitrate
Authors: Lurie D. , Yariv S.
Published: November 2013

In the heterometric titration of sodium montmorillonite with calcium nitrate, a titration curve comprising four stages is obtained. The first stage, attributable to the exchange reaction taking place at the sites of broken bonds, shows no change in transmittance upon addition of the salt. The second stage shows a decrease in transmittance attributable to the exchange reaction taking place in the interlayer space. The third stage demonstrates the completeness of the exchange reaction and the exclusive presence of calcium montmorillonite, since no change in transmittance takes place as the reagent is added. The fourth stage shows an increase in transmittance, but the reaction is obscure. The transition point, obtained by extrapolation of the straight portion of the second and third stages, is defined as the “endpoint” of the titration, and is equivalent to the exchange capacity of the clay.
Particle Interaction and Soil Swelling
Authors: Quirk J. P.
Published: November 2013

Particle interaction discussed in this paper may be limited, in which contiguous interacting plate shaped particles are within 10 Å of each other, or extensive, in which surface separations exceed 40 Å. Extensive swelling is caused by the interaction of Gouy‐Chapman diffuse double layers and the conditions under which diffuse double layer theory can be used to describe extensive swelling are re‐viewed. The essential feature of extensive swelling is its dependence on electrolyte concentration.

X‐ray studies of the variation of d(001) spacings for montmorillonite and vermiculite when saturated with divalent and large monovalent ions have been discussed as examples of limited swelling. This behaviour is contrasted with sodium montmorillonite which exhibits extensive crystalline swelling for concentrations less than 0.3 M NaCl.

The similarity of the swelling behaviour of a montmorillonite crystal and of a parallel assemblage of crystals constituting a domain has been noted and presented as an argument for domains being regarded as particulate entities in calcium saturated clay materials.

The limited crystalline swelling of calcium montmorillonite and domain swelling of calcium saturated clays is little affected by electrolyte concentrations less than molar. The inter‐crystalline swelling which occurs in soils and clay materials is triggered off by the adsorption of two layers of water; the adsorption of the two layers of water at areas of crystal overlap release mechanical energy stored as a result of crystal bending and packing on the drying cycle. This release of mechanical energy creates pores in which liquid is held by surface tension forces as distinct from water held at the clay solution interface by hydration and osmotic forces.

The use of chloride exclusion measurements to provide information on the nature of particle interaction is discussed. The information presented on domain structure and ion distribution at interfaces, as deduced from chloride exclusion measurements, reveals that diffuse double theory is completely inadequate for describing swelling of calcium clay systems and for predicting the pore solution composition.
Ferrous‐Ferric Ratio and CEC Changes on Deferration of Weathered Micaceous Vermiculite
Authors: Roth C. B. , Jackson M.L , Lotse E. G. , Syers J. K.
Published: November 2013

Ferrous iron in the layers increased 2‐fold or more on deferration of coarser fractions of micaceous vermiculite naturally weathered from biotite (Colorado and Transvaal sources). The ferric iron content of the layers was decreased by the deferration treatment but the original content was restored by subsequent H2O2 treatment. Sesquioxide coatings on micaceous vermiculite from Colorado, examined electron microscopically, were composed predominantly of Fe2O3 (80 to 85 percent), along with Al2O2 and SiO2. The CEC increased from 64 to 95 meq per 100 g in the fraction coarser than 1000 microns and 50 to 64 meq per 100 g in the fraction 2–0.2, microns in diameter, as a result of removal by deferration of positively charged sesquioxide coating which had originally blocked a portion of the CEC. Although treatment with H2O2 after deferration restored the Fe3+ content to approximately the original value, the CEC was not affected probably because of deprotonation OH− → O2− + H+ occurring simultaneous with Fe2+ → Fe3+.
Effect of Various Treatments on the Optical Properties of Montmorillonite Suspensions
Authors: Lahav N. , Banin A.
Published: November 2013

The light absorption spectra of Na, K, Ca and Ba‐montmorillonite suspensions were studied in relation to the procedure of sample preparation. These procedures included different sequences of transformations from one homoionic form into another, as well as a drying stage during the preparation.

The optical density was usually influenced by the method of preparation, indicating hysteresis effects in the transformation process. The data were interpreted in terms of tactoid formation and size.

Transformation of monovalent into divalent clay suspensions resulted in small tactoids. Air drying of the clay before the transformation resulted in larger tactoids in both mono‐ and divalent clays. Negative adsorption of chloride in Ca‐bentonite from two different preparations (which differed in their tactoid size) were in agreement with the light absorption measurements: the higher surface area was found in the suspension with the smaller tactoids.

The data available in the literature on negative absorption of chloride on montmorillonite are discussed. It is suggested that the discrepancies in the experimental results of different investigators could be, at least partially, explained by the differences in the preparation procedure of the clay suspensions.
Montmorillonite — S‐Triazine Interactions
Authors: Cruz Maribel , White J. L. , Russell J. D.
Published: November 2013

Adsorption of s‐triazines on montmorillonite surfaces results in hydrolysis and protonation of the s‐triazine compounds. Infrared studies suggest that dissociation of adsorbed water on the clay surface plays a major role in protonation and hydrolysis of the s‐triazine herbicides.
Statistical Models in the Study of Soil Properties
Authors: Karmeli D. , Kinsky J.
Published: November 2013

An objective study of soil properties is presented by means of statistical analysis using the least squares method. Elevation data and clay content, from six regions of an overall surveyed area, are approximated by linear and quadratic matrices. Regressions between a defined topography index of mean slopes and clay content are established. The level of significance of the relations is examined by means of computed “accounted map variability” and correlation coefficients. The results express the trend of the investigated property.
A Relationship Between the Conductivity and the Chloride Content in the Soil Extract and the Electromotive Force of the Soil Solution In Situ
Authors: Rinot M. , Goldberg S. D.
Published: November 2013

The electromotive force (emf) of a silver — silver chloride electrode in contact with moist clay loam, was found to be related to the specific conductivity of the 1:3 soil‐water extract. The chloride concentration of the extract was also well correlated with conductivity. Data from other sources show a generally similar trend existing for the variation of chloride concentration with conductivity of soil extracts from widely different soils. The proportion of chloride in the solution increases with total concentration, approaching a constant value at high concentrations. The relation of emf to the concentration, and its possible practical significance is noted.
Charge‐Transfer Complexes Between N‐Heteroaromatic Bases and their Salts
Authors: Shinitzky M.
Published: November 2013

Acridine, quinoline and isoquinoline are shown to form 1:1 charge transfer complexes with their protonated or methylated positively charged forms. The complexes exhibit characteristic charge‐transfer bands, part of which fall in the region where the components of the complex show no light absorption. The association constant K for mixtures containing acridine, quinoline or isoquinoline and their hydrochlorides or methochlorides in methanol‐water was derived from changes in intensity of the apparent charge‐transfer band with concentration of the free base. For the above mixtures in water, the association constant as well as the heat of complex formation ΔH were derived. The values of K and ΔH for the complexes formed between each of the three bases and their protonated forms are considerably higher than the analogous values for the complex with the methylated form, presumably due to a hydrogen bond between the coupled base molecules.
Preliminary Studies of the NMR Spectra of N‐Benzyl‐6‐Substituted Purines
Authors: Neiman Z.
Published: November 2013

In 7‐benzyl‐6‐mercaptopurine the benzylic methylene resonates at a lower magnetic field compared to other N‐benzyl groups and can be easily characterized. This deshielding effect is attributed to the magnetic anisotropy of the carbon6‐sulphur bond. In trifluoroacetic acid a slow proton‐exchange is observed for 1‐and 3‐benzyl‐6‐mercaptopurines but not for N‐benzyladenines.
Resolution Of N‐Benzyl‐Erythro‐β‐Hydroxy‐DL‐Aspartic Acid
Authors: Liwschitz Y. , Singerman A. , Wiesel Y.
Published: November 2013

Dakin's method for the resolution of erythro‐β‐hydroxy‐DL‐aspartic acid gives only incomplete separation. The N‐benzyl derivative of this amino acid, however, has been resolved by means of L‐histidine. Both antipodes are obtained optically pure and in practically quantitative yield.
The ISO‐Tetrahydrocannabinols
Authors: Gaoni Y. , Mechoulam R.
Published: November 2013

Synthetic routes are described which lead to iso‐tetrahydrocannabinols, a new series of structural isomers of the natural Δ1‐tetrahydrocannabinol. In this group of compounds a dihydrobenzopyran ring system is formed by cyclization of one of the phenolic groups of a cannabinoid with the C1 carbon in the terpene moiety of the molecule.
Tetrazolo Steroids
Authors: Mechoulam R.
Published: November 2013

The synthesis of a new group of steroids in which a tetrazole moiety is attached to A‐homo‐3 (or 4) ‐aza‐steroids is described.
Mixed Valence Compounds of Vanadium II. Properties and Formation Mechanism
Authors: Heitner‐Wirguin C. , Selbin J.
Published: November 2013

A second mixed valence compound of vanadium was obtained by decomposition of vanadyl (IV)bis (acetylacetonate) by fluoride ions in a nonpolar solvent. The compound has the formula [(C2H5)4N]4[V10O26F2H2] i.e. two oxygens of the previous compound [(C2H5)4N]4[V10O28H4] were replaced by fluoride ions. The thermal stability, electronic and ESR spectra are described. The properties of this compound are very similar to the compound obtained by addition of a halide ion (chloride, bromide or iodide) to vanadyl(IV) bis (acetylacetonate) in the presence of another metal complex. The mechanism of formation of these compounds is discussed.
Photoaddition of Acetylcyclohexane and Ethanol
Authors: Rubin M. B.
Published: November 2013

1‐Acetylcyclohexene undergoes photoaddition with ethanol to give, initially, cis‐ and trans‐2‐ethoxy‐1‐acetylcyclohexane. The thermodynamically less stable cis isomer is the major product. No products resulting from photochemical hydrogen atom abstraction from ethanol by photoexcited ketone were observed in contrast to the results obtained with an acetylcyclopentene derivative. The initially formed adducts undergo a further photochemical reaction, intramolecular hydrogen atom abstraction, to give derivatives of octahydrobenzofuran. Quantum yields for disappearance of acetylcyclohexene in ethanol were 0.04 at 2537Å and 0.25 at 3130Å.
Studies on Rat Liver Glutamine Synthetase
Authors: Gutter B. , Spiegelstein‐Klarfeld Hanna , Lichtenstein N.
Published: November 2013

Rat liver glutamine synthetase is activated by Mg++ and by Mn++. Optimal activity of the Mg++ activated synthetase occurred at about pH 7.8. The pH optimum of the Mn++ activated enzyme varied from 6.2 at low Mn++concentrations to 4.4 at high Mn++concentrations. α‐N‐Ethyl‐L‐glutamine inhibits the synthetase activity. The inhibition is of a mixed type. The synthetase is also inhibited, to a lesser degree, by α‐N‐propyl‐L‐glutamine but not by α‐N‐butyl‐L‐glutamine.
Fulvenes and Thermochromic Ethylenes. Part 52 The Fine Structure of 2‐Arylmethylene‐1,3‐Indandiones; their NMR and Infrared Spectra
Authors: Agranat I. , Loewenstein Ruth M. J. , Bergmann E. D.
Published: November 2013

A large number of 2‐arylmethylene‐1,3‐indandiones have been prepared and their nuclear magnetic resonance and infrared spectra have been measured. The measurements have been used to elucidate some details of the fine structure of these compounds.
Reactions Between Fulvic Acid, A Soil Humic Compound, and Montmorillonite
Authors: Schnitzer M. , Kodama H.
Published: November 2013

The magnitudes of d001 spacings of fulvic acid‐Na‐montmorillonite complexes were not affected by temperatures between 25 and 60°C. Slightly more than one half of the total amount of fulvic acid adsorbed by Na‐montmorillonite was in the interlamellar spaces, with the remainder on external surfaces. The d001 spacings and amounts of fulvic acid adsorbed in the interlamellar spaces of Pb++−, Mg++−, Co++− and Ni++− saturated montmorillonite decreased with increase in pH. The capacities of cation saturated clays to adsorb fulvic acid in interlamellar spaces decreased in the following order: Pb++ > Mg++ > Co++ > Ni++. The exotherm near 670°C in the DTA curve of the fulvic acid‐Na‐montmorillonite complex signalized the formation of an interlayer complex.
Reactive Collisions
Authors: Kuppermann A.
Published: November 2013

The present state of a priori calculations of chemical reaction cross sections is reviewed, with emphasis on the hydrogen atom plus hydrogen molecule reaction. Some comparison with experiment is included.
The Chemical Contribution to Sound Absorption. An Alternative Derivation
Authors: Perlmutter‐Hayman Berta
Published: November 2013

The expression for the chemical contribution to the coefficient of sound absorption is re‐derived. The derivation is based on a consideration of the energy dissipated when a chemical reaction takes place under non‐reversible conditions.
Copper Complexes Obtained from the Schiff Base of Quinoline‐2‐Aldehyde and Aliphatic Diamines
Authors: Kirson B. , Kassierer F.
Published: November 2013

Schiff base bis (2— quinolidene)‐ diamine gives a purple‐red complex with copper ions with a λmax at 530 mμ. The optimum pH for production of this complex is approximately 9.5. None of the metallic ions of the analytical groups II and III give rise to red complexes with the above Schiff base. Manganous (Mn2+) and stannous (Sn2+)ions as well as reducing agents such as hydrazine or hydroxylamine exert a catalytic effect on the rate of formation of these copper complexes. The thermal stability of the copper complex formed from the Schiff bases (2‐quinoline‐aldehyde with NH2‐(CH2)n‐NH2) is greater for diamine for which n = 4–6 than for n = 2–3.
Pyrolytic Reactions of Carbohydrates. Part V. Isothermal Decomposition of Cellulose in Vacuo
Authors: Halpern Y. , Patai S.
Published: November 2013

The thermal decomposition of cellulose in vacuo at 250,275 and 300°C was studied. The decomposition products appearing in different fractions were analyzed and the product ratios at different stages of the reaction were determined. A general scheme is proposed for the process.
Pyrolytic Reactions of Carbohydrates. Part VI. Isothermal Decomposition of Cellulose In Vacuo, in the Presence of Additives
Authors: Halpern Y. , Patai S.
Published: November 2013

The isothermal decomposition of cellulose at 250 and 275°C has been investigated in the presence of neutral, acidic, and basic additives. The composition of the volatile fractions and of the residue has been studied and the influence of the additives on the course of the thermal decomposition is discussed.
Pyrolytic Reactions of Carbohydrates, Part VIII. The Decomposition of D‐Glucose Labelled with 14C at Different Positions, Catalyzed by Various Additives
Authors: Houminer Y. , Hoz S. , Patai S.
Published: November 2013

The thermal decomposition of D‐glucose labelled with 14C either uniformly or at positions 1, 2 or 6 was studied at 250°C, in the presence of NaHCO3, CH3COONa, NaHSO4, NaH2PO4 or oxygen. The aqueous and tarry fractions were analysed and the amount and radioactivity of the evolved carbon dioxide and monoxide were determined. The effect of the additives on the pyrolytic processes, especially on the formation of the oxides of carbon is discussed. The presence of basic additives reduces the selectivity of different carbon atoms in the formation of volatiles. Both oxygen and nitrogen promote the formation of CO.
Simplistic Analysis of Reactive Scattering II. Initial and Final Distortions
Authors: Levine R. D.
Published: November 2013

The angular distribution of reactively scattered molecules is discussed in terms of a classical optical model. The deflection in a reactive scattering is considered, for direct reactions, as the sum of an initial and final deflection. The formal validation of this approach is discussed with a distorted wave approach and within a more general, reaction matrix formulation.
Transient Species in the Laser Photolysis at 265 Mμ of the Halogenobenzenes in Solution
Authors: Loeff I. , Lutz H. , Lindqvist L.
Published: November 2013

Pulsing cyclohexane or methanol‐water solutions of chlorobenzene and fluorobenzene with the Nd laser at 265 mμ (half‐height width 30 nsec) gives rise to intermediates, absorbing in the 290–300 mμ region, attributed to the corresponding triplet states. The decay of the triplet states is roughly first order with rate constants of (2.1 ± 0.1) × 106 sec−1 and (1.5 ± 0.1) × 106 sec−1 respectively. No transient absorption was observed with bromo‐ and iodobenzene under the same conditions. Solutions of the two latter compounds containing KI or KBr show the appearance of I−2 or IBr− following laser excitation.
Performance of gadoxetic acid‐enhanced MRI for detecting hepatocellular carcinoma in recipients of living‐related‐liver‐transplantation: Comparison with dynamic multidetector row computed tomography and angiography‐assisted computed tomography
Authors: Kakihara Daisuke , Nishie Akihiro , Harada Noboru , Shirabe Ken , Tajima Tsuyoshi , Asayama Yoshiki , Ishigami Kousei , Nakayama Tomohiro , Takayama Yukihisa , Okamoto Daisuke , Fujita Nobuhiro , Kishimoto Junji , Honda Hiroshi
Published: November 2013

Purpose

To clarify the diagnostic performance of gadoxetic acid‐enhanced MRI for the detection of hepatocellular carcinoma (HCC) in recipients of living related‐liver transplantation (LRLT).

Materials and Methods

This retrospective study group consisted of 15 patients with 61 HCCs who each underwent multidetector row computed tomography (MDCT), gadoxetic acid‐enhanced MRI, and angiography‐assisted computed tomography (CT) before LRLT. The three modalities were compared for their ability to detect HCC. Two blinded readers independently reviewed the images obtained by each modality for the presence of HCC on a segment‐by‐segment basis using a 5‐point confidence scale. The diagnostic performance of the modalities was evaluated in a receiver operating characteristic (ROC) analysis. The area under the ROC curve (Az), sensitivity, specificity, and accuracy were compared for the three modalities.

Results

No significant difference in Az, sensitivity, specificity, or accuracy was obtained among gadoxetic acid‐enhanced MRI, MDCT, and angiography‐assisted CT for both readers. For reader 1, the sensitivity (55.6%) and the accuracy (84.7%) of angiography‐assisted CT were significantly higher than those of MDCT (33.3% and 78.0%) (P < 0.05).

Conclusion

Gadoxetic acid‐enhanced MRI has a relatively high diagnostic ability to detect HCC even in recipients of LRLT, equivalent to the abilities of MDCT and angiography‐assisted CT. J. Magn. Reson. Imaging 2014;40:1112–1120. © 2013 Wiley Periodicals, Inc.