bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mineral Cordierite: Structure and Reactions in the Presence of Fluid Phases
Authors: Schreyer Werner
Published: July 2012

The complex framework silicate cordierite with a structure similar to that of beryl forms Al/Si‐ordered orthorhombic as well as disordered hexagonal polymorphs and varieties as a function of temperature and composition. Even in the stability range of the ordered cordierite initial crystallization leads to the disordered form that becomes gradually ordered via a modulated structure. A miscibility gap as a two‐phase loop exists between orthorhombic Mg‐cordierite of the composition Mg2[Al4Si5O18] and the new hexagonal, Bc‐bearing cordierite solid solutions formed by the substitutions Be[4]+Si for 2 Al[4]. (Na,K)‐bearing cordierites with the alkalies present in the structural channels are due to the substitution Alk+ + Al[4] for Si[4]. These metastable phases are hexagonal, probably because of the deviating Al/Si ratios that are not conducive to ordering. Neutral gas molecules and atoms like H2O, CO2, N2, and Ar can occupy the structural channels, H2O changing its dipole orientation depending on the presence or absence of Na in these channels. The pressure temperature stabilities of cordierite end members are mainly a function of the nature of their octahedrally coordinated atoms with PT‐ranges decreasing in the order Mg > Fe > Mn > Co; but there is also a stabilizing effect by gas channel occupants. Disordered cordierites form metastably at generally higher temperatures and lower pressures than their stable, ordered counterparts.
Transport of Ions Against their Concentration Gradient Across Cation Exchange Membranes
Authors: Schwahn P. , Woermann D.
Published: July 2012

The transport of mono‐ and bi‐valent cations against their concentration gradients across cation exchange membranes is studied experimentally under isothermal‐isobaric conditions. The driving forces of this transport are generated by a pH difference between the bulk phases of the membrane. A general theoretical analysis of the systems is given based on the model of the membrane with narrow pores. The extent of the observed stationary concentration increase of the ion species transported against its concentration gradient as well as the selectivity of the transport (if two ionic species are transported simultaneously) are in good agreement with theoretical predictions. Furthermore, results of electric transference experiments to separate two different kinds of mono‐valent counterion species are reported.
Selective Solvation of Some Silver(I) Salts in Water‐Pyridine Mixtures at 30°C
Authors: Palanivel A. , Rajendran G. , Kalidas C.
Published: July 2012

The selective solvation behaviour of silver(I) salts viz Ag2SO4, AgBrO3and AgIO3has been investigated in water‐pyridine (Py) mixtures at 30°C by solubility and emf measurements. It was observed that the solubilities of Ag2SO4, AgBrO3and AgIO3pass through a maximum near XPy= 0.5, XPy= 0.5 and XPy= 0.1 respectively and then decrease with further addition of Py. The Gibbs transfer energy of the silver ion, ΔG0t(Ag+) decreases continuously while that of the anions increases with the addition of Py. These results together with those concerning the solvent transport number Δ, are interpreted in terms of the heteroselective solvation of the salts, the silver ion being preferentially solvated by Pyand the anions by water.
Influence of Ionic Traces Upon the Electric Conductivity of an Electrolyte Solution. On the Possibility of Obtaining the Trace Mobility of an Ion Exclusively by Conductance Measurements
Authors: Raineri F. O. , Timmermann E. O.
Published: July 2012

In a detailed theoretical and experimental study it is shown that the initial slope for the dependence of the conductivity of an electrolyte solution with respect to the concentration of an added trace electrolyte is not only determined by the trace ionic conductivity of the non‐common ion added plus the ionic conductivity of the common ion at the concentration of the original (supporting) electrolyte, as has been proposed by H. G. Hertz et al. (J. Chim. Phys. 78, 68 (1981)). It is also determined in a non‐negligible amount by the variation of the equivalent conductivity of the pure supporting electrolyte with concentration as well as by the variation of this conductivity with the composition of the mixture at constant total concentration. The theoretical equations are verified with the complete electric transport data of the system HCl‐KCl‐H2O and careful conductivity measurements for the system NaCl‐KCl‐H2O. It is concluded that the trace ionic conductivity of an ion in a mixture cannot in general be obtained by conductivity measurements alone (transport number determinations are unavoidable) and the proposal due to Hertz et al. is shown to be inadequate. Only in the case of H+ as a trace ion the later two dependences mentioned above can be neglected within an error of 1% at relatively low concentrations of the supporting electrolyte.
The Low‐Pressure Pyrolysis of Butadiyne (C4H2)
Authors: Homann K. H. , Pidoll U. V.
Published: July 2012

Butadiyne (C4H2) mixed with helium (maximum 1:9) was pyrolyzed in a low‐pressure flow reactor at temperatures between 700 and 1000°C and total pressures of 3 to 13 mbar. The residence time (maximum 45 ms) was varied by a movable inlet lance for the C4H2. Samples were drawn through a molecular beam system and analyzed mass‐spectrometrically. The main products were C2H2, H2, polyyines (C6H2, C8H2), oligomers of the composition (C4H2)n, n = 2 to 5, polymer and coke. Most of the H2 and a smaller part of C2H2 and C6H2 were formed heterogeneously while the oligomers and C8H2 were generated in homogeneous reaction. The oligomers with n ≧ 3 are most probably aromatic compounds with C2H side groups. They are intermediates which repeatedly split off their C2H groups until the base hydrocarbons benzene, naphthalene, and phenanthrene or anthracene remain. Addition of C2H2 to the pyrolyzing C4H2 led to a mixed oligomerization while addition of H atoms had no measurable effect. A large part of the C4H2 decomposed heterogeneously with an apparent activation energy of 109 kJ mol−1. The activation energy for oligomer formation ranged from 145 to 168 kJ mol−1 increasing with higher degree of oligomerization. — A mechanism for the formation of polyynes and oligomers is discussed starting with an excited C4H2 which can add C4H2 to give either a linear or a branched dimer C8H2. The results are compared to the formation of polycyclic aromatic compounds in the burned gas of fuel‐rich flames that also contains C2H2 and C4H2.
Reaktormodelle für heterogen katalysierte Gasphasenreaktionen
Authors: Emig G.
Published: July 2012

In most chemical processes heterogeneously catalyzed gas‐phase reactions play an important role. Therefore, the modeling of the fixed bed reactors is increasingly important today. The aim of a model building procedure is to use information already available to predict the behavior of new catalysts, the optimization of process conditions, scale‐up, etc. The phenomena occuring in a reactor for heterogeneously catalyzed reactions vary greatly and are very complex, therefore, all models are only approximations with differing degrees of accuracies for the real system. In practice, however, it can be shown that relatively few simple model types can satisfactorily describe a large number of important cases. A priori criteria can aid in the decision when more complex models must be applied.
Reaction Sequences from Light Absorption to the Cleavage of Water in Photosynthesis—Routes, Rates and Intermediates
Authors: Witt H. T. , Schlodder E. , Brettel K. , Saygin Ö.
Published: July 2012

The reaction sequence between the primary electron acceptor, the oxidized Chlorophyll‐aII, and the terminal electron donor, the water splitting enzyme system S, is being described in the range from nanoseconds to milliseconds. For the cleavage of water Chlorophyll‐a+II extracts four electrons in four turnovers from the enzyme system S responsible for the water oxidation. For each extraction the electron is moved step by step along the chain that connects the Chlorophyll‐aII center with that of S. Beginning with the transfer from the immediate donor, D1 to Chl‐a+II, the subsequent transfer from D2 to D+I ends in the electron transfer from S to D2+. This final act establishes in S the oxidizing equivalent, probably in the form of oxidized manganese. Coupled with these acts is an intrinsic proton release and a surplus charge formation. After the generation of the 4th oxidizing equivalent in a concerted final action the evolution of O2 from water takes place. Correlations between the events are described quantitatively.
Nonlinear Phenomena in the Evolution of Satellite DNA
Authors: Stephan Wolfgang
Published: July 2012

Satellite DNA forms long clusters of tandemly repeated sequences of 104 to 107 copies, and is found in the chromosomes of all higher organisms. In particular in mammals, satellites comprise anywhere from a few percent (human) to over 50% (kangaroo rat) of total DNA. But a function of these highly abundant, noncoding sequences has not been identified so far, though a great deal of structural information has been gathered in the past 25 years. This paper looks at the structure‐function debate for satellite DNA. The basic question addressed is why are highly repeated sequences of no (obvious) functional significance such as satellite sequences tolerable in millions of copies in the chromosomes of higher organisms. A model is proposed which shows that the accumulation of clustered, highly repeated DNA (HRDNA) can most readily be explained as a result of synergistic effects of the forces of amplification, unequal crossing over and natural selection. Accordingly, satellite DNA clusters may build up only in those regions of the chromosomes where the effectiveness of unequal crossing over—operating as a nonlinear control mechanism and, in doing so, supporting selection—is drastically reduced. This result conforms well to the experimental finding that satellite DNA is located only in the genetically inactive parts of the chromosomes such as centromeres and telomeres, in which recombination is in general severely suppressed.
Model Calculations About the Reduction of Atmospheric Ozone by Different Halogenated Hydrocarbons
Authors: Krüger B. C. , Fabian P.
Published: July 2012

The impact of halogen radicals released from various halocarbons on atmospheric ozone has been studied by means of a time‐dependent one‐dimensional model. Different scenarios for future emissions rates, up to the year 2020, were used. The impact of chlorine is different from that of bromine which can be explained by the differences in the chemistry of the respective halocarbons themselves as well as of the inorganic halogen compounds in the atmosphere.
A Rheological Switch: Shear Induced Phase Transitions in Aqueous Surfactant Solutions
Authors: Rehage H. , Hoffmann H. , Wunderlich I.
Published: July 2012

Aqueous solutions of cationic surfactants show the striking phenomenon of shear induced phase transitions. Two different processes can be distinguished: At very low surfactant concentrations we observe flow induced sol → gel transitions and at higher concentrations shear induced transitions occur from a clear gel state to a turbid phase. The surfactant solutions act as a rheological switch and they can be used as elements which are sensitive to shear forces.
Polyethyleneoxide‐Dynamics in Aqueous Solutions Studied by Nuclear Magnetic Relaxation
Authors: Breen J. , Duijn D. Van , Bleijser J. De , Leyte J. C.
Published: July 2012

The local polymer dynamics of polyethyleneoxide in aqueous solutions were studied by 1H‐ and 13C‐nuclear magnetic relaxation. The concentration dependence is caused by polymer‐polymer interactions, whereas in the concentration independent range the polymer dynamics is mainly determined intramolecularly and by water‐PEO interactions. The latter interaction is influenced by the presence of salts. MW‐dependence of the relaxation rates is not observed for DP > 100. From the dispersion of the 1H relaxation rates, for a PEO‐sample with DP = 360 at a concentration of 0.5 mol/kg, the polymer segment dynamics are evaluated in terms of an overall and an internal motion.
A Narrow Window for Observation of Spiral Lipid Crystals
Authors: Heckl W. M. , Möhwald H.
Published: July 2012

The growth of spiral solid domains in monolayers of dimyristoylphosphatidic acid containing 1 mol% cholesterol is observed by fluorescence microscopy at the air/water interface. Spiral or lamellar domains are encountered only at high pH (11) where the large head group charge induces a chain tilt. Spiral width is drastically reduced with decreasing temperature, is uniform and can be varied reversibly.—The findings can be understood considering repulsive and anisotropically attractive electrostatic forces that increase with decreasing temperature and edge tension being reduced by incorporation of cholesterol. The shape of the spirals can be numerically calculated using a crude model containing only three adjustable parameters.
Hydrogen Abstraction Reactions by NH2(X̃2B1)‐Radicals from Hydrocarbons in the Gas Phase
Authors: Hack W. , Kurzke H. , Rouveirolles P. , Wagner H. Gg.
Published: July 2012

The NH2(X̃2B1) radical reactions with saturated hydrocarbons, toluene and acetaldehyde were investigated in an isothermal discharge flow system over the given temperature ranges. The pressure was varied between 2.6 and 7.8 mbar. Helium was used as the main carrier gas. The temperature dependences of the rates are represented by the following Arrhenius expressions, with A in [cm3 mol−1 s−1 and EA in [kJ mol−1]:

A correlation between the Arrhenius activation energy and the energy of the broken CH bond is discussed.
Integral Carbon Mass Balance in Premixed Sooting Flames
Authors: Brei M. , Jander H. , Wagner H. Gg.
Published: July 2012

In sooting C2H4‐air, C6H6‐air and C2H2‐air flames the burned gases have been analyzed for different fuel‐air ratios and the fractions of carbon which end up as CO and CO2, as soot and as hydrocarbons have been determined. The amount of soot formed increases strongly with increasing fuel content beyond the threshold of soot formation, following approximately the same formal relation for the different fuels. At a given fuel concentration above the soot threshold the soot mass per cm3 rises from C2H2 to C2H4 and to C6H6‐air flames. The concentrations of hydrocarbons in the burned gases increase also with increasing fuel concentrations but in different ways for the different fuels. For benzene‐air flames the carbon present as soot exceeds that present as hydrocarbon already at fuel concentrations slightly above the soot threshold. The same happens in C2H4‐air flames only at C/O ratios close to one and not at all for the C2H2‐air flames.—There is no uniquely simple correlation between the soot mass per cm3 formed in these flames of various fuels and the concentrations of hydrocarbon in their burned gases.
Defects and Cation Diffusion in Magnetite (VIII): Migration Enthalpies for Iron and Impurity Cations
Authors: Dieckmann R. , Hilton M. R. , Mason T. O.
Published: July 2012

Recent point defect formation and defect diffusion data in magnetite are used to analyze tracer diffusion data of Fe, Co, Cr and Al for motion enthalpies in vacancy and interstitial(cy) mechanisms. Correlations are made with ion properties such as radius, polarizability, and bond strength. The best correlation was made with the melting points of the end member ferrites containing the ions of interest. An explanation for the consistent minimum in diffusion coefficients is given.
A proton NMR study on the structure of water of hydration of aqueous micelles
Authors: El Seoud Monica I. , Farah João P. S. , El Seoud Omar A.
Published: July 2012

The chemical shift of water was measured as a function of concentration of the detergents cetyltrimethylammonium chloride. CTACl; 3‐N‐dodecyl‐N,N‐dimethylammonio‐1‐propanesulfonate, DDAPS; polyoxyethylene (9.5) octylphenyl ether, Triton X‐100, and the deuterium content of the solvent. The short chain compound butyltrimethylammonium bromide was also studied as a model for CTACl. Graphs of the chemical shifts vs. the mole fractions of the solubilizates were linear in all cases and the slopes were used to calculate the so called “fractionation factor, ϕ” which can be used as a measure of the degree of structure of the water of hydration of the appropriate species (relative to bulk water). The calculated ϕ values indicated that the butyltrimethylammonium ion does not perturb hydrogen bonding of the solvent (ϕ = 0.99), whereas the water in the Stern layer of CTACl is more organized than bulk water ( = 1.06). Zwitterionic DDAPS was found to enhance the structuring marginally (ϕ = 1.02) whereas the nonionic surfactant Triton X‐100 has a structure decreasing effect (ϕ = 0.95).
The molecular Zeeman effect of 2‐fluoropropane. A high resolution microwave fouriertransform study
Authors: Böttcher O. , Kleibömer B. , Sutter D. H.
Published: July 2012

A microwave Fouriertransform spectrometer, developed for rotational Zeeman effect studies is described. Its high resolution capabilities are demonstrated by the analysis of the dense Zeeman multiplets of 2‐fluoropropane. The diagonal elements of the molecular g‐tensor as referred to the principal inertia axes system are obtained as gaa = −0.00794(13), gbb = +0.00722(08), and gcc = −0.01051(11). The two independent molecular magnetic susceptibility anisotropies are obtained as 2χaa ‐ χbb ‐χcc = −2.77(34) · 10−6 erg G−2 mol−1 and 2χbb ‐ χcc ‐ χaa = −5.40(20) · 10−6 erg G−2 mol−1. The observed magnetic susceptibilities are compared with those observed earlier for propane and are discussed successfully within the model of local atom susceptibilities.
UV resonance raman studies on the structure of polyriboadenylic acid and adenosine 5'‐monophosphate depending on the pH value
Authors: Gfrörer A. , Schnetter M. , Wolfrum J. , Greulich K. O.
Published: July 2012

UV resonance Raman spectra of polyriboadenylic acid (poly(rA)) and adenosine‐5'‐monophosphate (AMP) were obtained with a Raman spectrometer based on an excimer/dye laser system. A pH‐induced structural transition between a single helical form and a double‐stranded structure of poly(rA) is documented by many characteristic spectral changes. We found a high degree of similarity for the spectral changes of AMP between pH 4.5 and pH 2.5 and poly(rA) between pH 7.0 and pH 4.5. The behaviour of the resonance Raman spectra of poly(rA) between pH 4.5 and pH 2.5 indicates a second structural change of poly(rA) which is different from the cooperative double‐strand formation at higher pH values.
The laser electron microscope (LEM)
Authors: Manuccia T. J. , Loda R. T.
Published: July 2012

We have developed a new SEM imaging mode which we refer to as laser electron microscopy (LEM). In this technique, a thin sample is mounted on a diamond substrate and overcoated with a phosphor having a highly temperature dependent cathodoluminescence (CL) emission intensity. The sample is held at low temperatures (T < 95 K) and is irradiated through the diamond substrate with a laser. Localized areas of the sample that absorb the laser radiation heat, and transfer this heat to the nearby phosphor coating, which is being simultaneously probed by the raster scanned electron beam. Thus, one detects a cathodoluminescence image of only those areas of the sample where the laser is absorbed. With IR irradiation, this interaction mechanism produces an image resembling that of a darkfield monochromatic infrared microscope but with the improved spatial resolution of electron beam imaging. One can then image the distribution of distinct molecular species.
35Cl NQR and X‐Ray Studies of Pentachloroethylstannate(IV) Salts
Authors: Storck Peter , Weiss Alarich
Published: July 2012

The 35CI NQR spectra of pentachloroethylstannate(IV) complex salts A2[(C2H5)SnCl5)] with four different cations A⊕ (A⊕ = Tetra‐ methylamnionium, [(CH3)4N]⊕ (I), Pyridinium, [CSHSNH]⊕ (II). Methylammonium, [CH3NH3]⊕ (III), and 4‐Picolinium, [4‐CH3 ‐ C5H4NH]⊕ (IV)) have been recorded and their crystal structures were determined. The compounds crystallize with a distorted K2PtCI6‐type structure ((I): space group C62h/c, a = 1408.9 pm, b = 1123.2 pm, c = 1332.7 pm, β = 90.94°, Z = 4; (II): space group C52h/c, a = 1618.8 pm, b = 744.6 pm, c = 1520.0 pm, β = 90.515°, Z = 4; (IV): space group Ct‐Pi, a = 1093.4 pm, b = 938.8 pm, c = 722.6 pm, α = 108.37°, β = 90.84', γ = 93.90, Z = 2 = (IV): space group D42‐P212121, a = 2181.1 pm, b = 1088.3 pm, c = 858.2 pm, Z = 4). The effects of the substitution of one Cl⊖ ligand within a SnCl2⊖6 octahedron by the stronger electron donor C2H⊖5 are: (a) The mean strength of all 5 Sn—Cl bonds is lowered. This is reflected by a decrease of the mean 35Cl NQR frequencies and an increase in Sn—Cl bond length compared with hexachlorostannates; (b) There exists a distinct cis and trans influence of the ethyl group. The Sn—Cl bonds in cis position to the ethyl group are highly weakened (cis‐weakening), while the trans effect is much smaller in magnitude and probably of opposite sign (trans‐strengthening). The influence of hydrogen bonds weakens Sn—Cl bonds in addition to cis‐weakening. A correlation of 35Cl NQR frequencies and Sn—Cl bond lengths shows a slope of —0.6 MHz/pm. The ethyl group is ordered in (II) and (III), disordered in (IV) and rotates in (I). In (I) a phase transition at 180 K could be detected by 35Cl NQR and DTA, the reason of which may be a freezing in of the ethyl group rotation.
Thermodynamical expectation values in restrained equilibria, dielectrical and electro‐optical relaxation strengths, and the Kerr effect of PMMA
Authors: Gallenkamp Uwe , Jungnickel Bernd‐J.
Published: July 2012

The Kerr effect of PMMA is composed of several relaxation steps which differ remarkably in their time scales. The relative strengths of these steps are quite different after application and removal of the electric field, respectively. In the present paper, general equations for such relaxation step strengths are derived considering that occasionally certain molecular motional modes are frozen in at a given observation temperature and, therefore, only restrained thermodynamic equilibria can be attained. The results are also applicable to any other, in case non‐linear, relaxation phenomenon. By means of the derived equations, the contributions of every relaxation step to the dielectric susceptibility and the Kerr constant are calculated, taking into account also possible orientation correlations between the relaxing structural units. With these relations, in turn, the dielectric permittivities and the Kerr constants of PMMA can be calculated. The derived equations, moreover, predict a peculiar cross‐over electro‐optical transient relaxation behaviour for molecules with suitable conformational degrees of freedom.
Electrochemical in‐situ investigations on polycrystalline gold electrodes with oscillating quartz crystals: Deposition and bulk diffusion of palladium
Authors: Stöckel Wolfgang , Schumacher Rolf
Published: July 2012

The electrochemical deposition of palladium on polycrystalline gold substrates was followed in the UPD range and under conditions where massive metal deposition occurs. These processes were studied by means of in‐situ microweighing, cyclic voltammetry and the registration of frequency and current with time. In addition, the diffusion kinetics of palladium into the gold substrate was studied under UPD conditions. The latter process leads to alloy formation. The electrosorption valency γ for palladium adsorbates was determined to be γ = 1.8. The apparent diffusion coefficient D of palladium into the gold electrode yields D ≈ 10−17 cm2/s for the conditions applied here.
The integrated intensities of chemically‐exchanging vibrational bands as given by the Bloch equations
Authors: Wood Kurt A. , Strauss Herbert L.
Published: July 2012

Recent predictions of dramatic integrated intensity changes in vibrational bands undergoing collapse due to chemical exchange are the result of improper normalization factors inserted into the Bloch‐equation treatment. For the correct form of the Bloch equations, integrated intensity is approximately conserved. However, even in this case the problems inherent in applying the Bloch equations to vibrational systems remain.
Rates and mechanisms of the reactions of ethanol and propanol with fluorine and chlorine atoms
Authors: Khatoon T. , Edelbüttel‐Einhaus J. , Hoyermann K. , Wagner H. Gg.
Published: July 2012

The reactions of C2H5OH (1), C2H5OD (2), C2D5OD (3), 1‐C3H7OH (4), 2‐C3H7OH (5), 2‐C3H7OD (6) with F atoms and the reactions of C2H5OH (7), 1‐C3H7OH (8), 1‐C3H7OD (9), 2‐C3H7OD (10) with Cl atoms have been studied in a discharge flow reactor and a Laval nozzle reactor at room temperature and at pressures of a few mbar. Samples of the reaction mixtures were withdrawn continuously by a molecular beam device and analyzed by a mass spectrometer. The rates of the reactions were measured relative to the standard reactions C2H6 + F (0) and C2H6 + Cl (00) yielding k1/k0 = 1.06, k2/k0 = 1.25, k3/k0 = 1.20, k4/k0 = 1.26, k5/k0 = 1.06, k6/k0 = 1.20, k7/k00 = 2, k9/k00 = 4. For the reactions of F atoms with alcohols the probability of attack at one of the alkyl H atoms was found to be five times less than at the hydroxyl H atom site. For the reactions of Cl atoms with alcohols no abstraction from the OH group was observed, the abstraction from the alkyl groups follows the thermodynamically favoured route by forming mainly secondary radicals.
Association between weight gain during pregnancy and neural tube defects and gastroschisis in offspring
Authors: Yang Wei , Carmichael Suzan L. , Tinker Sarah C. , Shaw Gary M. ,   the National Birth Defects Prevention Study
Published: July 2012

BACKGROUND

Limited information is available about the association of maternal weight gain during pregnancy and birth defects. The objective of this study was to investigate the association of maternal weight gain with neural tube defects (NTDs) and gastroschisis among offspring.

METHODS

We used data from the National Birth Defects Prevention Study, an ongoing multicenter, population‐based, case‐control study. Mothers of cases and controls were interviewed by telephone. Analyses included 255 anencephaly, 577 spina bifida, 648 gastroschisis cases, and 5587 controls with deliveries from 1999 to 2005. After subtracting birth weight, the associations of total and average weekly weight gain (kg) with each phenotype were estimated, stratified by gestational age (<37 vs. ≥37 weeks) and adjusted for relevant covariates.

RESULTS

Among deliveries <37 weeks gestation, mothers of infants with anencephaly and spina bifida had lower weight gains compared to control mothers; no association between weight gains and gastroschisis was observed. Among deliveries ≥37 weeks, mothers of infants with anencephaly had lower weight gains during pregnancy; a similar association was not observed for spina bifida; mothers of infants with gastroschisis were twice as likely to have weight gains in the highest quartile. Stratification by maternal age (gastroschisis) or body mass index (BMI) or race/ethnicity (all phenotypes) did not alter odds ratio estimates.

CONCLUSION

Altered weight gain during pregnancy may be a consequence of carrying an NTD/gastroschisis affected fetus or a marker for underlying factors common to the etiology of these birth defects. It is possible that whatever mechanisms influence weight gain may also influence the development of NTDs and gastroschisis, but in opposite directions.
High‐Performance Liquid Chromatographic Enantioseparation of Unusual Isoxazoline‐Fused 2‐Aminocyclopentanecarboxylic Acids on (+)‐(18‐Crown‐6)‐2,3,11,12‐Tetracarboxylic Acid‐Based Chiral Stationary Phases
Authors: Sipos László , Ilisz István , Aranyi Anita , Gecse Zsanett , Nonn Melinda , Fülöp Ferenc , Hyun Myung Ho , Péter Antal
Published: July 2012

The enantiomers of four unusual isoxazoline‐fused 2‐aminocyclopentanecarboxylic acids were directly separated on chiral stationary phases containing (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid as chiral selector. The nature of the alcoholic modifier (MeOH, EtOH, IPA) exerted a great effect on the retention, whereas the selectivity and resolution did not change substantially. Two types of dependence of retention on alcohol content were detected: k1 increased continuously with increasing alcohol content or a U‐shaped retention curve was observed. A comparison of the chromatographic data obtained with HCOOH, AcOH, TFA, HClO4, H2SO4, or H3PO4 as acidic modifier at a constant concentration demonstrated that in most cases, larger k values were obtained on the application of AcOH or HCOOH, and an increase of the acid content resulted in a decrease of retention. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes and selector. The sequence of elution of the enantiomers was determined in all cases. Chirality 24:817‐824, 2012. © 2012 Wiley Periodicals, Inc.
Layout optimization method for magnetic circuit using multistep utilization of genetic algorithm combined with design space reduction
Authors: Okamoto Yoshifumi , Tominaga Yusuke , Sato Shuji
Published: July 2012

Layout optimization with ON/OFF information of magnetic material in finite elements is one of the most attractive tools in the initial conceptual and practical design of electrical machinery for engineers. Heuristic algorithms based on random search allow engineers to define general‐purpose objects. However, there are many iterations of finite element analysis, and it is difficult to achieve a practical solution without island and void distribution by using a direct search method, such as simulated annealing (SA), genetic algorithm (GA), and so on. This paper presents a layout optimization method based on GA. The proposed method can arrive at a practical solution by means of multistep utilization of the GA, and the convergence speed is considerably improved by using it in combination with reduction of the design space. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(3): 19‐30, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22290
Energy and emission analysis in the malaysian food industries
Authors: Ali M.B. , Saidur R. , Hasanuzzaman M. , Ward T.A.
Published: July 2012

According to the source paper written in 2006, the Malaysian food industrial sector accounted for about 14% of the total manufacturing energy consumption. As energy costs rapidly increase, alternative energy sources and efficiency improvements become essential to energy planning, cost savings, resource optimization, and environmental protection in these industries. This article focuses on the energy savings, economic benefits, and emission reduction that can be obtained by applying various energy saving options. This study shows that significant power can be saved annually by utilizing energy efficient motors. The cost savings, payback period, and reduction in CO2 emissions are estimated for different motor loads. It is shown that sizeable amounts of energy can be saved using VSD, waste heat recovery, new efficiency lamps (T‐5), and repairing leakages. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 777–783, 2013
KSRP: A checkpoint for inflammatory cytokine production in astrocytes
Authors: Li Xuelin , Lin Wei‐Jye , Chen Ching‐Yi , Si Ying , Zhang Xiaowen , Lu Liang , Suswam Esther , Zheng Lei , King Peter H.
Published: July 2012

Chronic inflammation in the central nervous system (CNS) is a central feature of many neurodegenerative and autoimmune diseases. As an immunologically competent cell, the astrocyte plays an important role in CNS inflammation. It is capable of expressing a number of cytokines such as tumor necrosis factor alpha (TNF‐α) and interleukin‐1 beta (IL‐1β) that promote inflammation directly and through the recruitment of immune cells. Checkpoints are therefore in place to keep tight control over cytokine production. Adenylate/uridylate‐rich elements (ARE) in the 3′ untranslated region of cytokine mRNAs serve as a major checkpoint by regulating mRNA stability and translational efficiency. Here, we examined the impact of KH‐type splicing regulatory protein (KSRP), an RNA binding protein which destabilizes mRNAs via the ARE, on cytokine expression and paracrine phenotypes of primary astrocytes. We identified a network of inflammatory mediators, including TNF‐α and IL‐1β, whose expression increased 2 to 4‐fold at the RNA level in astrocytes isolated from KSRP−/− mice compared to littermate controls. Upon activation, KSRP−/− astrocytes produced TNF‐α and IL‐1β at levels that exceeded control cells by 15‐fold or more. Conditioned media from KSRP−/− astrocytes induced chemotaxis and neuronal cell death in vitro. Surprisingly, we observed a prolongation of half‐life in only a subset of mRNA targets and only after selective astrocyte activation. Luciferase reporter studies indicated that KSRP regulates cytokine gene expression at both transcriptional and post‐transcriptional levels. Our results outline a critical role for KSRP in regulating pro‐inflammatory mediators and have implications for a wide range of CNS inflammatory and autoimmune diseases. © 2012 Wiley Periodicals, Inc.
Sex‐related differences of cAMP‐specific PDE4B3 mRNA in oligodendrocytes following systemic inflammation
Authors: Johansson Emily M. , Sanabra Cristina , Mengod Guadalupe
Published: July 2012

Sex‐related differences have been observed in the incidence and severity of several neurological diseases and in sepsis in humans. Cyclic adenosine monophosphate (cAMP) has been shown to play an important role in modulating the inflammatory environment during neuroinflammation and importantly in protecting myelin from excitotoxic cell death. Considering the sexual dimorphism in the functional properties of oligodendrocytes and the importance of a systemic inflammation in the progression of multiple sclerosis, we focused on identifying possible sex‐related differences in the alterations previously reported for the two phosphodiesterase4B (PDE4B) splice‐variants (PDE4B2 and PDE4B3) mRNA expression during innate neuroinflammation. PDE4A, PDE4B, and PDE4D are present in oligodendrocytes and we have previously reported that PDE4B3 mRNA is readily expressed in both oligodendrocytes and neurons. In this study, we analyzed the influence of an intraperitoneal lipopolysaccharide injection on the distribution pattern and expression levels of the PDE4B mRNA splicing variants in both male and female mice brains. Clear differences were observed in PDE4B2 and PDE4B3 mRNA expression levels in males compared with females in a time‐dependent manner. Furthermore, we observed that the clear downregulation of PDE4B3 mRNA was reflected in a lower percentage of oligodendrocytes positive for this transcript which correlated with a decrease in inducible cAMP early repressor expression in female corpus callosum. © 2012Wiley Periodicals, Inc.
Determination of synthetic wind functions for estimating open water evaporation with Computational Fluid Dynamics
Authors: Vidal‐López P. , Martínez‐Alvarez V. , Gallego‐Elvira B. , Martín‐Górriz B.
Published: July 2012

A computational fluid dynamics (CFD)‐based methodology is proposed to derive convective mass‐transfer coefficients (wind functions) that are required for estimating evaporation of water bodies with the mass‐transfer method. Three‐dimensional CFD was applied to model heat transfer in two water bodies: a Class‐A tank evaporimeter and an on‐farm artificial pond. The standard k–ɛ model assuming isotropic turbulence was adopted to describe turbulent heat transport, whereas the heat and mass transfer analogy was assumed to derive the wind functions.

The CFD‐derived wind functions were very similar to those empirically derived from the experimental water bodies. The evaporation rates calculated with the synthetic wind functions were in good agreement with hourly and daily evaporation measurements for the tank and pond, respectively. The proposed CFD‐approach is generalisable and cost effective, because it has low input data requirements. Besides, it provides additional capability of modelling the spatial distribution of the evaporation rate over the water surface. Although the application of CFD to water bodies evaporation modelling is still in development, it looks very promising. Copyright © 2012 John Wiley & Sons, Ltd.
A reliable and efficient first principles‐based method for predicting pKa values. 4. organic bases
Authors: Zhang Shuming
Published: July 2012

The ionization (dissociation) constant (pKa) is one of the most important properties of a drug molecule. It is reported that almost 68% of ionized drugs are weak bases. To be able to predict accurately the pKa value(s) for a drug candidate is very important, especially in the early stages of drug discovery, as calculations are much cheaper than determining pKa values experimentally. In this study, we derive two linear fitting equations (pKa = a × ΔE + b; where a and b are constants and ΔE is the energy difference between the cationic and neutral forms, i.e., ΔE = Eneutral−Ecationic) for predicting pKas for organic bases in aqueous solution based on a training/test set of almost 500 compounds using our previously developed protocol (OLYP/6‐311+G**//3‐21G(d) with the the conductor‐like screening model solvation model, water as solvent; see Zhang, Baker, Pulay, J. Phys. Chem. A 2010, 114, 432). One equation is for saturated bases such as aliphatic and cyclic amines, anilines, guanidines, imines, and amidines; the other is for unsaturated bases such as heterocyclic aromatic bases and their derivatives. The mean absolute deviations for saturated and unsaturated bases were 0.45 and 0.52 pKa units, respectively. Over 60% and 86% of the computed pKa values lie within ±0.5 and ±1.0 pKa units, respectively, of the corresponding experimental values. The results further demonstrate that our protocol is reliable and can accurately predict pKa values for organic bases. © 2012 Wiley Periodicals, Inc.
Computational prediction of monosaccharide binding free energies to lectins with linear interaction energy models
Authors: Mishra Sushil Kumar , Sund Johan , Åqvist Johan , Koča Jaroslav
Published: July 2012

The linear interaction energy (LIE) method to compute binding free energies is applied to lectin‐monosaccharide complexes. Here, we calculate the binding free energies of monosaccharides to the Ralstonia solanacearum lectin (RSL) and the Pseudomonas aeruginosa lectin‐II (PA‐IIL). The standard LIE model performs very well for RSL, whereas the PA‐IIL system, where ligand binding involves two calcium ions, presents a major challenge. To overcome this, we explore a new variant of the LIE model, where ligand–metal ion interactions are scaled separately. This model also predicts the saccharide binding preference of PA‐IIL on mutation of the receptor, which may be useful for protein engineering of lectins. © 2012 Wiley Periodicals, Inc.
Comparison of three humanized mouse models for adoptive T cell transfer
Authors: Volk Andreas , Hartmann Sylvia , Muik Alexander , Geiß Yvonne , Königs Christoph , Dietrich Ursula , von Laer Dorothee , Kimpel Janine
Published: July 2012

Background

Humanized mouse models for adoptive T cell transfer are important for preclinical efficacy and toxicity studies. However, common xenograft models using immunodeficient mice have so far failed to efficiently support the homing of human T cells to secondary lymphoid tissues.

Methods

We established a new mouse model for the adoptive transfer of genetically‐modified (gm) T cells using conditioned BALB/c mice. Conditioning involved cyclophosphamide injections, lethal irradiation and radioprotection with bone marrow from immunodeficient mice. We compared repopulation kinetics and the quality of grafts in these modified Trimera (mT3) mice with immunodeficient BALB/c Rag2−/− interleukin (IL)2 receptor gamma (rg) knockout (DKO) and NOD/LtSz‐scid IL2rg−/− (NSG) recipient mouse strains.

Results

DKO mice showed only marginal engraftment until onset of graft‐versus‐host disease, whereas mT3 and NSG were repopulated with comparable kinetics. However, T cell repertoire and human cytokine profiles suggest a xenoreactivity‐driven gm T cell expansion in mT3 mice, whereas NSG mice were characterized by an initial homeostatic proliferation. Morphological analysis revealed high levels of human gm T cell infiltration in the spleen and liver of all three mouse strains. However, mT3 mice provided the strongest homing of human gm T cells to mucosal sites. Additionally, mT3 mice were the only model with macroscopically visible superficial inguinal lymph nodes. These lymph nodes strongly supported the homing of gm T cells.

Conclusions

In the present study, we give proof‐of‐concept that wild‐type mice can accept gm T cell grafts while providing secondary lymphoid structures. Despite limitations, mT3 mice are a valid alternative for applications that specifically rely on improved secondary lymphoid structures. Copyright © 2012 John Wiley & Sons, Ltd.
Posttraumatic stress disorder and memory: Evidence of maladaptations to stressors
Authors: Ashby Erin L. , Cornelius Allen
Published: July 2012

People with posttraumatic stress disorder (PTSD) are entering the workforce in record numbers as they discharge from the military and attempt to enter the civilian workforce. Understanding how PTSD affects the human mind will help organizations manage their employees more effectively by allowing supervisors to set up systems that compensate for deficits. PTSD appears to cause significant memory and attentional deficits; however, it is difficult to determine whether the attentional deficits contribute to the memory deficits. The current study used the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to examine the memory deficits separate from the attention difficulties in people with PTSD. Results demonstrated that PTSD severity correlated with attention issues, but not memory issues. The authors discuss these findings in terms of their clinical and organizational applications.
Horned grebe habitat use of constructed wetlands in Alberta, Canada
Authors: Kuczynski Eva C. , Paszkowski Cynthia A. , Gingras Bev A.
Published: July 2012

Wetland degradation has resulted in declines in populations of aquatic birds throughout North America. Horned grebe (Podiceps auritus), a migratory diving bird experiencing population decline, may benefit from wetland construction. We examined horned grebe use of borrow pits (ponds created during highway construction) in Alberta, Canada. Our goals were to document patterns of occurrence and breeding success of grebes on borrow pits and to determine if occupied and unoccupied sites differed in local habitat or landscape characteristics. In May 2003 and 2007, 330 constructed ponds were surveyed for horned grebes. We chose 100 occupied and 100 unoccupied ponds for additional surveys in 2007 and 2008, and collected habitat and landscape data for these sites. We used generalized linear mixed model and generalized linear model regression, coupled with Akaike's Information Criterion, to determine which environmental variables were most effective in explaining occurrence of horned grebes. The best model included all measured local and landscape habitat features. Horned grebes occurred on 36% of ponds in May 2003 and 2007, and chicks were produced on 74.5–81.3% of occupied ponds in 2007 and 2008. Grebes occupied larger ponds with more emergent and riparian vegetation and avoided ponds that supported beavers, contained human structures, and were primarily surrounded by forest within 1 km. On ponds with grebe pairs, chicks were produced more often on sites surrounded by more riparian vegetation. We conclude that the construction of small wetlands offers a promising means of increasing breeding habitat for horned grebes and present specific recommendations for breeding pond construction. © 2012 The Wildlife Society.
On the resolvent arising in a parameter‐elliptic multi‐order boundary problem
Authors: Faierman M.
Published: July 2012

In this paper we consider a boundary problem for a parameter‐elliptic, multi‐order system of differential equations defined over a bounded region in \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathbb {R}^n$\end{document} and under limited smoothness assumptions as well as under boundary conditions which include those of Dirichlet. Information is then derived concerning the asymptotic behaviour of the trace of a power of the resolvent of the Hilbert space operator, in general non‐selfadjoint, induced by the boundary problem under null boundary conditions. This information will then be used in a subsequent work to derive various results pertaining to the asymptotic behaviour of the eigenvalues of this operator.
Assessing the reproducibility of dynamic contrast enhanced magnetic resonance imaging in a murine model of breast cancer
Authors: Barnes Stephanie L. , Whisenant Jennifer G. , Loveless Mary E. , Ayers Gregory D. , Yankeelov Thomas E.
Published: July 2012

Quantitative dynamic contrast enhanced magnetic resonance imaging estimates parameters related to tissue vascularity and volume fractions; additionally, semiquantitative parameters such as the initial area under the curve can be utilized to describe tissue behavior. The aim of this study was to establish the reproducibility of quantitative and semiquantitative analysis of dynamic contrast enhanced magnetic resonance imaging in a murine model of breast cancer. For each animal, a T1‐weighted, gradient‐echo sequence was used to acquire two sets of dynamic contrast enhanced magnetic resonance imaging data separated by 5 h. Data were acquired at both a 0.05 mm3 (1282, n = 12) and a 0.2 mm3 (642, n = 12) resolution, and analysis was performed using both the Tofts–Kety (to estimate Ktrans and ve) and extended Tofts–Kety (Ktrans, ve, and vp) models. Reproducibility analysis was performed for both the center slice and the total tumor volume for all parameters. For the total volume analysis, the repeatability index for Ktrans is 0.073 min−1 in the standard model analysis and 0.075 min−1 in the extended model analysis at the 1282 acquisition. For the 642 acquisition, the values are 0.089 and 0.063 min−1 for the standard and extended models, respectively. The repeatability index for initial area under the curve was 0.0039 and 0.0042 mM min for the 1282 and 642 acquisitions, respectively. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.