bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Neuroanatomy and Sleep‐Disordered Breathing: Implications for Autonomic Regulation
Authors: Harper Ronald M. , Kumar Rajesh , Macey Paul M. , Ogren Jennifer A. , Richardson Heidi L. 
Published: July 2012

AbstractA major concern with sleep‐disordered breathing conditions, which include obstructive sleep apnea (OSA), central apnea, and congenital central hypoventilation syndrome (CCHS), is the high incidence of accompanying autonomic dysfunction and metabolic disorders. Patients with OSA show exaggerated sympathetic tone, leading to hypertension, cardiac arrhythmia, profuse sweating, impaired cerebral perfusion, and stroke. In addition, OSA appears in 86% of obese Type II diabetic patients, suggesting common deleterious processes. Autonomic deficiencies also appear in CCHS patients, who are often hypoglycemic. The impaired autonomic control may stem from injury to central sympathetic and parasympathetic regulatory areas resulting from apnea‐related inflammation, hypoxia, or perfusion‐related consequences in OSA, and genetic mutation repercussions in CCHS. Disturbed sleep organization from apnea arousals may also disrupt hormonal release. Brain areas affected in both OSA and CCHS include cortical and limbic regions that influence hypothalamic‐regulated sympathetic control and hormone release, essential for glycemic regulation, as well as parasympathetic nuclei influencing the pancreas and other viscera, and raphé serotonergic sites, important for thermal and vascular regulation. Brain injury and altered functional responses appear in OSA and CCHS, assessed with magnetic resonance imaging techniques, in areas which show regional gray matter loss, alterations of free water within tissue, loss of axonal integrity, and disruption of functional responses to autonomic and ventilatory challenges. Evaluation of neural injury and distortion in functional signals to autonomic challenges in localized brain areas can provide insights into common pathological mechanisms for dysregulation of hormonal release and autonomic processes in sleep‐disordered breathing and metabolic disorders. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.
The Thermal Conductivity of Hydrogen, Deuterium and Their Mixtures Near Room Temperature within the Pressure Range 2  36 MPa
Authors: Clifford A. A. , Kestin J. , Wakeham W. A. 
Published: July 2012

AbstractThe paper reports new, absolute measurements of the thermal conductivity of hydrogen and deuterium as well as of two binary mixtures of the two components at 27.5°C. The measurements have been carried out as a function of density in a transient hot‐wire instrument and extend over the pressure ranges 2  13 MPa for the mixtures and 2  36 MPa for pure hydrogen. The uncertainty in the absolute thermal conductivity data is estimated as one of ±0.2%. The measurements have been arranged so as to yield the ratio of the thermal conductivities of the two pure gases with essentially the same uncertainty.  The Eucken factors for the two pure hydrogen isotopes at zero density have been derived and differ from each other by as much as 1.8% which is well beyond experimental uncertainty. The existing kinetic theory expressions for the Eucken factor of a polyatomic gas are not able to account for this difference. On the other hand the first density coefficients for the thermal conductivity of the two hydrogen isotopes are found to be the same within the limits of experimental error.
Polarisationsoptische mikrospektralphotometrische Untersuchung zur Bindungsgeometrie von intercaliertem Ethidiumbromid. Theorie für die Lichtabsorption orientierter doppelbrechender Fäden
Authors: Ohmes Ernst , Pauluhn Jürgen , Weidner Jörg‐Ulrich , Zimmermann Herbert W. 
Published: July 2012

AbstractDer Farbstoff Ethidiumbromid, E, geht zwei verschiedene Bindungen mit DNA ein. Beide Bindungen lassen sich durch ihr Verhalten gegenüber Salzen wie NaCl, MgCl2 usw. unterscheiden. Die nicht‐kompetitive Bindung 1 wird durch Salze nicht beeinflußt. Demgegenüber wird E aus der kompetitiven Bindung 2 durch Salze verdrängt. Wir haben untersucht, ob die nicht‐kompetitive Bindung 1 von E an Kalbsthymus‐DNA mit der intercalativen Bindung identisch ist. — Mit einer speziellen Technik wurde ein gelartiger E‐DNA‐Komplex hergestellt, der nur nicht‐kompetitiv gebundenen Farbstoff enthielt. Durch Recken von Fäden oder Filmen des Gels gelang es in einigen Fallen, hoch orientierte mikroskopische Präparate herzustellen. Die Lichtabsorption der E‐DNA‐Proben wurde in der längstwelligen Rande mit polarisiertem Licht in einem Mikrospektralphotometer quantitativ untersucht. Das Präparat befand sich zwischen Polarisator und Analysator des Spektralphotometers. α und β sind die Winkel zwischen der Vorzugsrichtung k des Präparats und den Schwingungsrichtungen ep und ea von Polarisator und Analysator. Das Verhältnis I(α,β)/I0(α,β) der Intensitäten des durchtretenden Lichts mit und ohne Präparat wurde als Funktion der Winkel α und β gemessen. Die Untersuchungen ergaben, daß das durchtretende Licht im allgemeinen elliptisch, in Sonderfällen linear oder zirkular polarisiert ist. — Bei der Auswertung der Experimente müssen Doppelbrechung und Dichroismus der Probe berücksichtigt werden. Es wird ein Formalismus angegeben, der I(α,β)/I0(α,β) als Produkt eines Polarisationsfaktors P = P(α,β) und eines Absorptionsfaktors Q = Q(α,Aj,Ak) beschreibt. Ak und Aj sind die Extinktionen für monochromatisches Licht, das in Richtung k oder j ⟂ k schwingt. Das auf Doppelbrechung korrigierte dichroitische Verhältnis R0 = Ak/Aj ist aus Q experimentell zugänglich. Der beste Wert für die längstwellige Absorptionsbande des Farbstoffs (ṽ = 19600 cm−1) beträgt R0 = 0,03. — Aus dem Formalismus läßt sich eine Größe K ableiten, die der Schichtdicke d der Probe proportional ist. K ist experimentell zugänglich. Die Orientierung der Probe ist um so besser, je kleiner d und damit K sind. Der Zusammenhang zwischen R0 und K läßt sich für kleine K durch eine Gerade approximieren. Für K → 0 kann auf das bestmögliche dichroitische Verhältnis R0 = 0,00 ± 0,02 extrapoliert werden. — Die längstwellige Absorptionsbande von E ist in der Ebene des Heterocyclus polarisiert. Aus dem Grenzwert R0 = 0,00 kann geschlossen werden. daß im Idealfall die Achse der Doppelhelix in Richtung k und das übergangsmoment des Farbstoffs senkrecht zu k orientiert sind. Diese Bindungsgeometrie des nicht‐kompetitiv gebundenen Farbstoffs entspricht dem Intercalationsmodell.
The Optical Matching Phenomenon in Water/Oil‐Microemulsions
Authors: Eicke Hans‐Friedrich , Kubik Rudolf 
Published: July 2012

AbstractOptical matching phenomena were observed with water/AOT/isooctane (W/O) microemulsions. The phenomenon has been interpreted on the basis of Rayleigh's scattering theory in combination with a quantitative relation between the macroscopic dielectric constant of the microemulsion and the dielectric properties of its constituents. A residual scattering contribution at the [H2O]/[AOT]‐ratio, where the system meets the optical matching condition, could be very satisfactorily assigned to density fluctuations of the surfactants in the water/oil‐interface, hence explaining the apparent polydispersity of these microemulsions.
Experimentelle Prüfung von approximativen Chiralitätsfunktionen am Beispiel induziert cholesterischer Lösungen (III): Induktion durch chirale 2,2′‐Spirobiindan‐Derivate
Authors: Korte E. H. , Chingduang P. , Richter W. J. 
Published: July 2012

AbstractChirale Spirobiindan‐Derivate induzieren in nematischen Flüssigen Kristallen eine cholesterische Molekülanordnung. Der resultierende Schraubungssinn und die Ganghöhe (bezogen auf die eingesetzte Konzentration chiraler Substanzen) werden als charakteristische Meßgröße einer Chiralitätsbeobachtung in guter Näherung durch eine approximative Chiralitätsfunktion beschrieben.
The Electrooxidation of Glucose in Phosphate Buffer Solutions: Kinetics and Reaction Mechanism
Authors: Ernst S. , Heitbaum J. , Hamann C. H. 
Published: July 2012

AbstractThe electrochemical oxidation of glucose on Pt at pH = 7.5 within 400 ≤ ϕRHE ≤ 800 mV was studied by cyclic voltammetry, by taking quasistationary current‐potential curves, by measuring the surface coverage of organic residues, and by analyzing the primary reaction product. The results can be summarized as follows:1. Glucono lactone is the only reaction product being formed by the anodic process. Gluconic acid is generated by hydrolysis.2. Tafel lines had to be normalized for the uncovered surface with the help of the adsorption measurements. The apparent transfer coefficient is αapp = 0.37 ± 0.03.3. The electrochemical reaction orders of glucose and H+ were determined to be zG = 0.35 ± 0.04 and zH+ = −0.38 ± 0.04. resp.These results are interpreted by means of a reaction mechanism. The kinetic parameters measured are confirmed by a model calculation.
The Direct Photolysis of Tetramethylsilane in the Gas and Liquid Phases
Authors: Bastian E. , Potzinger P. , Ritter A. , Schuchmann H.‐P. , von Sonntag C. , Weddle G. 
Published: July 2012

AbstractThe photolysis of tetramethylsilane at the long wavelength side of the absorption spectrum gives rise to two main primary photochemical processes: A simple SiC bond‐breaking process with a quantum yield of 0.55 ± 0.17 and a methane elimination reaction with a quantum yield of 0.22 ± 0.07. The radicals disappear by recombination and addition reactions to dimethylsilaethylene. Only an upper limit for the ratio of disproportionation to recombination of 0.13 for the trimethylsilyl radicals can be given. Beside the radical addition reaction dimethylsilaethylene also dimerizes. A semiquantitative evaluation of the data shows that the radical addition reaction as well as the dimerisation reaction proceed with a negligible activation energy.
Study of Spectral Sensitization and Supersensitization by Means of the Rotating Ring‐Disk Electrode Technique
Authors: Watanabe Tadashi , Nakao Masashi , Fujishima Akira , Honda Kenichi 
Published: July 2012

AbstractRotating ring‐disk electrode (RRDE) technique, using a ZnO single crystal as the disk electrode, was applied to the study of spectral sensitization by rhodamine B (RhB) and supersensitization by hydroquinone (HQ) in acetonitrile. The primary product of spectral sensitization, i. e., RhB radical cation (RhB+·), was detected electrochemically at the Pt ring electrode. Upon addition of HQ to the electrolyte solution, the sensitized photocurrent was enhanced (supersensitization), and concomitantly the collection efficiency for RhB+· at the Pt ring electrode showed a decrease. Assuming that the supersensitization results from the reduction of RhB+· by HQ, the rate constant for this process was calculated to give 106 − 107 M−1 s−1. Taking into account the singlet lifetime of RhB* as well as the rate constant for the quenching of RhB* by HQ, the mechanism of spectral sensitization and supersensitization is discussed.
A Thermodynamic Analysis of Phase Transitions of Crystals with Structural Disorder
Authors: Schmalzried H. 
Published: July 2012

AbstractCrystals with high point defect disorder exhibit on overexponential increase of their defect dependent properties with temperature, sometimes combined with phase transitions. It is shown that these experimental facts may be interpreted by explicitly taking into account the dependence of the defect formation energy and entropy upon the molar volume of the crystal.
Hydrogen Diffusion through the Semiconductor‐Liquid‐Junction on TiO2 (Rutile) Electrodes
Authors: Schumacher Rolf 
Published: July 2012

AbstractReduction of TiO2 (rutile) single crystals with hydrogen at temperatures considerably higher than room temperature leads, in addition to the formation of oxygen vacancies, to crystal structures where hydrogen is chemically bound inside the crystal. Investigations on such crystals have revealed that bound hydrogen becomes sufficiently mobile at temperatures above 450°C so that it can leave the crystal. In contrast to that, the mobility of unbound interstitial hydrogen ions is much higher even at room temperature. It was shown that unbound interstitial hydrogen leaves the crystal by two different mechanisms: above an internal electric field strength, Es, close to the surface of 106 V cm−1 as protons, whereas below that value as atoms.
Charge Transfer across Organic Photoconductor/Insulating Liquid Interfaces. Part II: Metal Free Phthalocyanine/Dodecane Containing Electron Donor/Acceptor Molecules
Authors: Ahuja R. C. , Hauffe K. 
Published: July 2012

AbstractThe phenomenon of charge transfer through the metal free Phthalocyanine/Dodecane interface has been investigated using a transient technique. It is reported that the photoinjected charge, interfacial charge transfer efficiency and overall quantum yield are mainly controlled by the presence of foreign molecules in Dodecane. The effect of about 30 different molecules (electron donor/acceptor) on the relevant parameters is presented. The results are discussed qualitatively and an attempt has been made to correlate the results to the relevant molecular parameters.
Charge Transfer across Organic Photoconductor/Insulating Liquid Interfaces. Part III: Copper Phthalocyanine, Chlorinated Copper Phthalocyanine/Dodecane Containing Electron Acceptor/Donor Additives
Authors: Ahuja R. C. , Hauffe K. 
Published: July 2012

AbstractThe results on the charge transfer processes at the Copper phthalocyanine/Dodecane interfaces are described. The photocharge injection was investigated (using a transient measurement technique) as a function of electric field, intensity and wavelength of light and the nature and concentration of various electron donor/acceptor additives. While CuPC demonstrates positive and negative charge injection, no negative charge injection could be detected with Cl‐CuPC. The photocharge injection follows the order H2PC > CuPC > ClCuPC. The results have been explained qualitatively.
Investigation of the Phase Transition Kinetics Liquid ⇌ Vapour by a Pressure‐jump Relaxation Technique
Authors: Schulze Friedrich‐Wilhelm , Cammenga Heiko K. 
Published: July 2012

AbstractThe construction and performance of an apparatus for the kinetic study of mass transfer processes between gaseous and condensed phases is described. In this method, phase equilibrium is suddenly disturbed by the generation of a pressure jump in the gaseous phase after which the establishment of the new equilibrium state is followed by a sensitive pressure gauge. The application of the method to the kinetics of evaporation and condensation of liquids is described. For water at 20.0°C the evaporation coefficient is found to be α = 1.00 ± 0.037 and the condensation coefficient αc = 0.98 ± 0.067. This is the first unambiguous proof that for resting water α = αc = 1.
Photopolymerization of a Diacetylene‐Phenazine Mixed Crystal
Authors: Braunschweig F. , Bässler H. 
Published: July 2012

AbstractPhotopolymerization of mixed crystals of 2,4‐heptadecadiynoic acid and phenazine was studied under optical excitation of either the phenazine at 420 nm or the diacetylene monomer at 280 nm. Polymer absorption at 514 nm or dark‐ and photoconductivity were used as a probe to continuously monitor product formation. The reaction velocity is constant up to about 10 percent conversion and decreases in a linear fashion for 0.15 ≲ c ≲ 0.4. Consequently, energy transfer from the primarily excited state to polymer molecules must be negligible for c < 0.1. This yields a upper limit of 10−11 s for the lifetime of the optical precursor state which must be of singlet character. At 290 K the quantum efficiencies are E(420) = 0.1 and E(280) = 0.5 for phenazine and diacetylene excitation, respectively. The activation energies for photopolymerization are E(420) = 0.21 ± 0.02 eV and E(280) = 0.17 ± 0.02 eV. E(280) is attributed to chain growth whereas E(420) − E(280) ≈︁ 0.04 eV has to be associated with formation of a chain initiation species as a result of sensitizer excitation. Electron transfer between diacetylene and the excited phenazine is excluded as the rate‐determining step for the sensitized reaction.
Experimentelle Prüfung von approximativen Chiralitätsfunktionen am Beispiel induziert cholesterischer Lösungen: Chirale Methan‐Derivate II
Authors: Richter W. J. , Heggemeier H. , Schrader B. , Krabbe H. J. , Korte E. H. 
Published: July 2012

AbstractDie induzierten HTP‐Werte von 27 chiralen Methan‐Derivaten, zusammengefaßt in 6 Pentupeln, werden auf ihre Beschreibbarkeit durch approximative Chiralitätsfunktionen untersucht. Der qualitative Aspekt dieser Chiralitätsbeobachtungen wird durch Chiralitätsfunktionen angemessen erfaßt; zur Bestimmung von ligandenspezifischen Parametern sind diese Funktionen nur in wenigen Fällen eine gute Näherung. Als Basis zur Bestimmung des Zusammenhanges von absoluter Konfiguration der Gastmoleküle und dem Vorzeichen des induzierten HTP‐Wertes sind diese Parameter bisher weniger geeignet als das Sequenzregelverfahren.
Molare Entropien von Salzschmelzen zwischen 600 K und 3000 K
Authors: Richter J. , Vreuls W. , Winthagen W. 
Published: July 2012

AbstractDie molare Entropie geschmolzener Salze einer Gruppe des Periodensystems mit einem gemeinsamen Anion hängt in sehr guter Näherung linear vom Kationenradius ab. Die Extrapolation der molaren Entropie für gegen Null gehenden Kationenradius (rk → 0) liefert den Anteil der molaren Entropie für dieses gemeinsame Anion, aus dem sich mit experimentellen Daten die zugehörigen Kationenanteile der Entropie und weitere Anionenanteile berechnen lassen. Mit diesen Ionenanteilen läßt sich die molare Entropie einer großen Anzahl von geschmolzenen Salzen in einem Temperaturbereich von 600 K bis 3000 K je nach dem Schmelz‐ und Siedepunkt bzw. der Zersetzungstemperatur mit einer Abweichung von etwa 2,5% abschätzen.
Pressure Effect on the Two‐Phase Region and the Electrical Conductivity in Liquid Bi  BiBr3 Mixtures
Authors: Tamura K. , Hoshino H. , Endo H. 
Published: July 2012

AbstractThe pressure variation of the two‐phase region in liquid Bi  BiBr3 mixtures was studied by measuring the conductivity as a function of temperature up to 17 kbar using an internally heated autoclave and a piston‐cylinder apparatus. The retrograde solubility region disappears at about 1.5 kbar. The two‐phase region disappears at about 16 kbar and the liquidus curve with S‐shape appears at about 17 kbar. Around 55 mol‐% Bi the electrical conductivity changes sharply at high pressures where the two‐phase region diminishes.
Physikalisch‐chemische Untersuchungen an geordneten Histon/Polynukleotidkomplexen
Authors: Klump H. , Hütig H. 
Published: July 2012

AbstractEs ist heute allgemein akzeptiert, daß native DNA in den Chromosomen als hochgeordneter Komplex aus DNA und dem Histonoktamer (H2A, H2B, H3, H4)2 vorliegt. Diese Komplexe können isoliert und aufgereinigt und in einzelne Nukleosomen zerlegt werden. Durch Erhöhung der Ionenstärke läßt sich der Komplex dissoziieren und bei sorgfältiger Erniedrigung der Ionenstärke läßt sich die native Struktur wieder reassoziieren. In dieser Arbeit wird für eine Reihe von Polynukleotiden gezeigt, daß für die Ausbildung der geordneten Histon‐komplexe das Vorhandensein einer doppelhelikalen Struktur, entweder in Form einer DNA‐Helix oder einer RNA‐Helix, ausreichend ist. Einzelsträngige Polynukleotide wie Poly A oder Poly C bilden mit den Histonen keine geordneten Strukturen. Aufgrund der Ergebnisse dieser Untersuchung kann man schließen, daß die Histone ausschließlich zur dichten Packung der DNA in den Chromosomen gebraucht werden.
Temperature‐Dependent Hyperfine Coupling Constants. An ESR Study of Some Substituted N‐Hydropyridinyl Radicals in Solution
Authors: Sander Ulrich , Dohrmann Jürgen K. 
Published: July 2012

AbstractThe hyperfine splittings of the radicals N‐hydro‐4‐methylpyridinyl (1), N‐hydro‐2,6‐dimethylpyridinyl (2), and N‐hydro‐4‐cyanopyridinyl (3) have been measured as a function of temperature in propanol(‐2)/acetone. The temperature coefficients of the NH proton splitting in radicals 1 and 2 are exceptionally large. The temperature‐dependence of the ring proton splittings has been analyzed using the model of localized out‐of‐plane vibrations of the protons. The estimated frequencies are given. The NH proton frequencies, ṽ1, increase in the following order: ṽ1 (2) < ṽ1 (1) < ṽ1, (3). The contributions to the NH proton splitting from out‐of‐plane vibration and σ‐π spin polarization have been determined. A value of — 3.1 ± 0.2 mT is obtained for the spin polarization parameter of the NH bond in the fixed planar structure of the radicals.
Die Adsorption von Benzonitrilen an der Quecksilberelektrode in wasserfreiem Acetonitril
Authors: Wegert H. , Baumgärtel H. 
Published: July 2012

AbstractMit Hilfe der phasenselektiven Wechselstrompolarographie wird die Adsorption von Benzonitrilen an einer Quecksilberelektrode in wasserfreiem Acetonitril gemessen. ΔGads, ΔHads und ΔSads des Adsorptionsprozesses werden bestimmt. Das Adsorptionsverhalten von Benzonitrilen wird durch die Langmuir‐Isotherme beschrieben. Durch Substitution von Benzonitril mit CH3‐, CH3O‐ und weiteren Nitrilgruppen kann gezeigt werden, daß das Dipolmoment der Moleküle keinen Einfluß auf deren Adsorptionsverhalten ausübt. Zunehmende π‐Elektronendichte des aromatischen Rings erhöht die Fähigkeit der Moleküle, spezifisch an der Elektrode zu adsorbieren. Es wurde eine lineare Energiebeziehung zwischen der Freien Adsorptionsenthalpie und der Zahl der Substituenten gefunden.
Investigation of the Fluorescence Behaviour and the Primary Step in the Photoreaction of Various 3‐ and 4‐Substituted Sydnones
Authors: Eber G. , Schneider S. , Dörr F. 
Published: July 2012

AbstractThe quantum yields of fluorescence and photochemical reaction, as well as fluorescence decay times of several sydnone derivates were measured in dependence on temperature. It was found that not only the rate of radiationless transitions was temperature dependent but also the one of the radiative decay. Furthermore, evidence is given that the photochemically reactive state is a 3ππ*‐state.
Excess Enthalpies of Liquid α,ω‐Dichloroalkane + n‐Hexane Mixtures. A Group Contribution Study of the Cl  Cl Proximity Effect
Authors: Polo Carmelo , Gutierrez‐Losa Celso , Kechavarz Mohammad‐Reza , Kehiaian Henry V. 
Published: July 2012

AbstractEnthalpies of mixing at 298.15 K are reported for the following binary mixtures: 1,2‐dichloroethane +, 1,3‐dichloropropane +, 1,4‐dichlorobutane +, 1,5‐dichloropentane +, and 1,6‐dichlorohexane + n‐hexane. — These experimental results, along with literature data on enthalpies of mixing of dichloromethane + n‐hexane or + n‐heptane, 1‐chlorobutane + n‐hexane or + n‐nonane, and 1‐chlorooctane + n‐hexane or + n‐octane, are interpreted in terms of molecular surface interactions between the groups Cl, CH3, and CH2 in the quasichemical approximation. — Comparison of the enthalpy of the Cl/aliphatic‐interchange parameters reveals a decrease of the inter‐molecular interactions with decreasing intramolecular ClCl distance in the various α,ω‐dichloroalkanes (proximity effect).