bluuebunny/crossref_metadata_2025 huggingface dataset:
Melatonin and its precursor,L‐tryptophan: influence on pancreatic amylase secretion in vivo and in vitro
Authors: Jaworek Jolanta , Nawrot Katarzyna , Konturek Stanisław J. , Leja‐Szpak Anna , Thor Piotr , Pawlik Wiesław W.
Published: June 2010

Abstract: Melatonin, considered as a main pineal product, may be also synthetized in the gastrointestinal tract froml‐tryptophan. Melatonin has been recently shown to affect insulin release and its receptors have been characterized in the pancreas however, the effects of melatonin on the pancreatic enzyme secretion have not been examined. The aim of this study was to investigate the effects of melatonin orl‐tryptophan on amylase secretion in vivo in anaesthetized rats with pancreato‐biliary fistulas, and in vitro using isolated pancreatic acini. Melatonin (1, 5 or 25 mg/kg) orl‐tryptophan (10, 50 or 250 mg/kg) given to the rats as a intraperitoneal (i.p.) bolus injection produced significant and dose‐dependent increases in pancreatic amylase secretion under basal conditions or following stimulation of enzyme secretion by diversion of bile‐pancreatic juice. This was accompanied by a dose‐dependent rise in melatonin plasma level. Stimulation of pancreatic enzyme secretion caused by melatonin orl‐tryptophan was completely abolished by vagotomy, deactivation of sensory nerves with capsaicin or pretreatment with CCK1receptor antagonists (tarazepide orl‐364,718). Pretreatment with luzindole, an antagonist of melatonin MT2receptor failed to affect melatonin‐ orl‐tryptophan‐induced amylase secretion. Administration of melatonin (1, 5 or 25 mg/kg i.p.) orl‐tryptophan (10, 50 or 250 mg/kg i.p.) to the rats resulted in the dose‐dependent increase of cholecystokinin (CCK) plasma immunoreactivity. Enzyme secretion from isolated pancreatic acini was not significantly affected by melatonin orl‐tryptophan used at doses of10−8–10−5 m. We conclude that exogenous melatonin, as well as that produced endogenously froml‐tryptophan, stimulates pancreatic enzyme secretion in vivo while increasing CCK release. Stimulatory effect of melatonin orl‐tryptophan on the exocrine pancreas involves vagal sensory nerves and the CCK release by these substances.
RETRACTED: Melatonin prevents lipopolysaccharide‐induced hyporeactivity in rat
Authors: D'Emmanuele Di Villa Bianca Roberta , Marzocco Stefania , Rosanna Di Paola , Autore Giuseppina , Pinto Aldo , Cuzzocrea Salvatore , Sorrentino Raffaella
Published: June 2010

Abstract: Melatonin (MT) is the principal secretory product of the pineal gland and its role as an immumo‐modulator is well established. Recent evidence shows that MT exerts protective effects in septic shock, hemorrhagic shock and inflammation. Lipopolysaccharide (LPS), fromEscherichia coli, administered to animals directly stimulates a number of cells and systems to produce various inflammatory mediators. LPS‐induced septic shock is characterized by hypotension and vascular hyporeactivity to contracting agents. In particular, the reactive oxygen species such as superoxide and nitric oxide (NO) contribute to the pathophysiology of septic shock. In this study, we demonstrate that MT pretreatment prevents the hyporeactivity to phenylephrine in vivo and in aorta rings collected from rats treated with the endotoxin. The beneficial effect of MT seems related to its antioxidant properties and with inhibition of inducible nitric oxide synthase (iNOS) protein expression, reduction of NO production and nitrotyrosine formation, in aorta, preventing vascular, and endothelial injury. Additionally, we first demonstrate, that MT inhibited nuclear enzyme poly (ADP‐ribose) synthetase activation in vascular tissue. The current study underlined the protective effect of MT on the vascular dysfunction associated with septic shock, data that could support the clinical use of MT in human endotoxemia.
Age‐related changes in murine CNS mRNA gene expression are modulated by dietary melatonin
Authors: Sharman Edward H. , Sharman Kaizhi G. , Ge Yuan‐Wen , Lahiri Debomoy K. , Bondy Stephen C.
Published: June 2010

Abstract:  Brain cellular functions decline with normal aging, accompanied by a changing profile of gene expression. Gene array analysis was used to quantitatively estimate messenger RNA (mRNA) expression levels in the cerebral cortex of both young (4‐month) and old (27‐month) B6C3F1 male mice. A stringent degree of significance was obtained by using multiple gene chips. Out of 12,423 mRNA levels, only 25 changed significantly with age. Nine of these genes coded for inflammatory proteins, all of which were elevated in aged, relative to younger mice. Melatonin (200 p.p.m.) included in the diet of aged animals for 8 wk elevated serum and cortical melatonin and reversed 13 of the 25 genes altered with age. In no case did melatonin potentiate age‐related changes in gene expression. The restoration of a more youthful gene profile to brains of aged animals by melatonin, to a large extent, involves reversal of age‐induced elevation of basal inflammatory parameters.
Circadian rhythms of dopamine, glutamate and GABA in the striatum and nucleus accumbens of the awake rat: modulation by light
Authors: Castañeda Tamara R. , de Prado Blanca Marquez , Prieto David , Mora Francisco
Published: June 2010

Abstract: Using microdialysis, we investigated the circadian rhythms of the extracellular concentrations of dopamine, glutamate andγ‐aminobutyric acid (GABA) in the striatum and nucleus accumbens of the awake rat. Wistar rats were maintained in a 12 hr dark:12 hr light (12:12) cycle for 2 wk before the experiment began. The neurotransmitter levels were measured every 30 min for 30 hr in control (maintaining the 12:12 cycle) or in experimental conditions under a 24‐h light period (continuous light) or under a 24‐h dark interval (continuous dark). The dopamine metabolites, DOPAC and HVA, and the main serotonin metabolite, 5‐HIAA, were measured along with arginine and glutamine under all conditions. In 12:12 conditions, a circadian rhythm of dopamine, glutamate and GABA was found in both the striatum and nucleus accumbens. Again under 12:12 conditions, DOPAC, HVA, 5‐HIAA, and arginine, but not glutamine, fluctuated in a circadian rhythm. In the striatum under constant light conditions, there was a circadian rhythm of dopamine, glutamate, GABA, DOPAC and HVA, but not 5‐HIAA. By contrast, when the rats were kept under continuous dark, dopamine and its metabolites, DOPAC and HVA (but not glutamate and GABA), did not fluctuate in a circadian rhythm. In the nucleus accumbens, under both constant light or dark conditions, no changes were found in the circadian rhythm in any of the neurotransmitters and metabolites studied. These findings show that in the striatum, dopamine but not glutamate and GABA, seem to be influenced by light. In the nucleus accumbens, however, the three neurotransmitters had a circadian rhythm, which was independent of light.
Melatonin reduces disseminate neuronal death after mild focal ischemia in mice via inhibition of caspase‐3 and is suitable as an add‐on treatment to tissue‐plasminogen activator
Authors: Kilic Ertugrul , Kilic Ülkan , Yulug Burak , Hermann Dirk M. , Reiter Russel J.
Published: June 2010

Abstract:  The effects of i.p. melatonin (4 + 4 mg/kg, after induction of ischemia and at reperfusion onset) administered either alone or in combination with the thrombolytic tissue‐plasminogen activator (t‐PA, 10 mg/kg), on cerebral laser Doppler flow (LDF) and ischemic injury were studied after 30 min of middle cerebral artery (MCA) thread occlusion in male C57BL/6 mice. Thread occlusions resulted in reproducible focal ischemias, followed by hyperperfusion reactions immediately after thread withdrawal, as revealed by LDF measurements. Compared with animals receiving normal saline (peak LDF after reperfusion: 172.0 ± 24.2%), postischemic LDF was significantly attenuated in animals treated with melatonin (105.1 ± 6.7%, P < 0.05). Delivery of t‐PA (132.8 ± 22.3%) or t‐PA plus melatonin (164.7 ± 36.7%), on the contrary, did not influence postischemic LDF recordings. Twenty‐four hours after reperfusion, melatonin treated mice had significantly increased neuronal survival and decreased disseminate cell injury in the ischemia‐vulnerable striatum, as investigated by cresyl violet and terminal transferase biotinylated‐dUTP nick end labeling stainings. The protective effects were associated with inhibition of caspase‐3 activity. Melatonin administration also increased neuronal survival after 30 min MCA occlusion in animals treated with t‐PA, although t‐PA itself already decreased the degree of injury in a significant manner. Our data demonstrate that melatonin reduces disseminated neuronal injury in the striatum after mild focal ischemia. Brain protection is independent of hemodynamic changes and involves inhibition of caspase‐3.
Approximately disentangling exponential operators
Authors: Scholz Daniel , Voronov Volodymyr G. , Weyrauch Michael
Published: June 2010

A new method for the approximate disentangling of exponential operators based on the Baker–Campbell–Haussdorff theorem is suggested and implemented in a computer program. The operators to be disentangled must form a finite-dimensional Lie algebra. The accuracy of the method is tested and demonstrated in several explicitly calculated examples, where exact analytic solutions are available.
On the assessment of hydroxyapatite fluoridation by means of Raman scattering
Authors: Campillo M. , Lacharmoise P. D. , Reparaz J. S. , Goñi A. R. , Valiente M.
Published: June 2010

Hydroxyapatite is the main mineral component of bones and teeth. Fluorapatite, a bioceramic that can be obtained from hydroxyapatite by chemical substitution of the hydroxide ions with fluoride, exhibits lower mineral solubility and larger mechanical strength. Despite the widespread use of fluoride against caries, a reliable technique for unambiguous assessment of fluoridation in in vitro tests is still lacking. Here we present a method to probe fluorapatite formation in fluoridated hydroxyapatite by combining Raman scattering with thermal annealing. In synthetic minerals, we found that effectively fluoride substituted hydroxyapatite transforms into fluorapatite only after heat treatment, due to the high activation energy for this first order phase transition.
The influence of refractive index change and initial bending of cantilevers on the optical lever readout method
Authors: Dohn S. , Greve A. , Svendsen W. E. , Boisen A.
Published: June 2010

It has been speculated that the initial bending of cantilevers has a major influence on the detector signal in a cantilever-based sensor using the optical lever readout method. We have investigated theoretically as well as experimentally the changes induced in the detector signal when the optical lever technique is used to monitor a cantilever with initial bending during changes in the refractive index of the surrounding media. We find that for changes in refractive index as small as 10−4 the detector signal is highly dependent on the initial bending of the cantilever. The findings are validated experimentally using an environmental chamber and varying the pressure. We sketch routes to circumvent the problem and formulas suitable for data treatment are given.
Isotope dependent, temperature regulated, energy repartitioning in a low-barrier, short-strong hydrogen bonded cluster
Authors: Li Xiaohu , Oomens Jos , Eyler John R. , Moore David T. , Iyengar Srinivasan S.
Published: June 2010

We investigate and analyze the vibrational properties, including hydrogen/deuterium isotope effects, in a fundamental organic hydrogen bonded system using multiple experimental (infrared multiple photon dissociation and argon-tagged action spectroscopy) and computational techniques. We note a qualitative difference between the two experimental results discussed here and employ ab initio molecular dynamics simulations to explain these results. A deeper understanding of the differences between the isotopically labeled systems arises from an analysis of the simulated cluster spectroscopy and leads to a system-bath coupling interpretation. Specifically, when a few active modes, involving the shared hydrogen/deuterium stretch, are identified and labeled as “system,” with all other molecular vibrational modes being identified as “bath” modes, we find critical differences in the coupling between the system modes for the shared proton and shared deuteron cases. These differences affect the energy repartitioning between these modes resulting in a complex spectral evolution as a function of temperature. Furthermore, intensity borrowing across modes that are widely distributed in the frequency domain plays an important role on the simulated spectra.
Hot carriers in a bipolar graphene
Authors: Balev O. G. , Vasko F. T.
Published: June 2010

Hot carriers in a doped graphene under dc electric field is described taking into account the intraband energy relaxation due to acoustic phonon scattering and the interband generation-recombination transitions caused by thermal radiation. The consideration is performed for the case when the intercarrier scattering effectively establishes the quasiequilibrium electron-hole distributions, with effective temperature and concentrations of carriers. The concentration and energy balance equations are solved taking into account an interplay between weak energy relaxation and generation-recombination processes. The nonlinear conductivity is calculated for the momentum relaxation caused by the elastic scattering. The current-voltage characteristics, and the transition between bipolar and monopolar regimes of conductivity are obtained and analyzed, for different temperatures and gate voltages.
Oxidation and the origin of the two-dimensional electron gas in AlGaN/GaN heterostructures
Authors: Miao M. S. , Weber J. R. , Van de Walle C. G.
Published: June 2010

The surface of the AlGaN barrier layer in AlGaN/GaN high electron mobility transistors has strong and hitherto unexplained effects on transistor characteristics. Indeed, it has been cited as the source of the two-dimensional electron gas at the AlGaN/GaN interface. Using computational methods based on density functional theory, we investigate surface reconstructions on realistic GaN and AlN (0001) surfaces, which are invariably oxidized. Numerous structures with different oxide coverage and different stoichiometry are examined, and their stability is interpreted in terms of driving mechanisms such as the electron counting rule and oxide-stoichiometry matching. We discuss which structures are likely to form under a variety of oxidation conditions, and show that these structures explain the observed dependence of electron density on thickness and variations in surface barrier height.
On the possibility of collective attraction in complex plasmas
Authors: Chaudhuri M. , Kompaneets R. , Morfill G. E.
Published: June 2010

An investigation on the possible collective electric attraction between like-charged dust particles has been performed in an isotropic homogeneous complex (dusty) plasma in which a balance between plasma creation due to ionization and plasma loss due to the absorption on dust particles has been reached. The analysis is made on the basis of a self-consistent fluid model, which includes plasma ionization, plasma loss on dust particles, dust charge variations, and ion-neutral friction. It is shown that the interaction potential can have an attractive part in the stability regime of the ionization-absorption balance with respect to ion perturbations only under very limited circumstances.
Extracting nanobelt mechanical properties from nanoindentation
Authors: Zhang Yin
Published: June 2010

A three-spring-in-series model is proposed for the nanobelt (NB) indentation test. Compared with the previous two-spring-in-series model, which considers the bending stiffness of atomic force microscope cantilever and the indenter/NB contact stiffness, this model adds a third spring of the NB/substrate contact stiffness. NB is highly flexural due to its large aspect ratio of length to thickness. The bending and lift-off of NB form a localized contact with substrate, which makes the Oliver–Pharr method [W. C. Oliver and G. M. Pharr, J. Mater. Res. 7, 1564 (1992)] and Sneddon method [I. N. Sneddon, Int. J. Eng. Sci. 3, 47 (1965)] inappropriate for NB indentation test. Because the NB/substrate deformation may have significant impact on the force-indentation depth data obtained in experiment, the two-spring-in-series model can lead to erroneous predictions on the NB mechanical properties. NB in indentation test can be susceptible to the adhesion influence because of its large surface area to volume ratio. NB/substrate contact and adhesion can have direct and significant impact on the interpretation of experimental data. Through the three-spring-in-series model, the influence of NB/substrate contact and adhesion is analyzed and methods of reducing such influence are also suggested.
Design, implementation, and testing of a cryogenic loading capability on an engineering neutron diffractometer
Authors: Woodruff T. R. , Krishnan V. B. , Clausen B. , Sisneros T. , Livescu V. , Brown D. W. , Bourke M. A. M. , Vaidyanathan R.
Published: June 2010

A novel capability was designed, implemented, and tested for in situ neutron diffraction measurements during loading at cryogenic temperatures on the spectrometer for materials research at temperature and stress at Los Alamos National Laboratory. This capability allowed for the application of dynamic compressive forces of up to 250 kN on standard samples controlled at temperatures between 300 and 90 K. The approach comprised of cooling thermally isolated compression platens that in turn conductively cooled the sample in an aluminum vacuum chamber which was nominally transparent to the incident and diffracted neutrons. The cooling/heat rate and final temperature were controlled by regulating the flow of liquid nitrogen in channels inside the platens that were connected through bellows to the mechanical actuator of the load frame and by heaters placed on the platens. Various performance parameters of this system are reported here. The system was used to investigate deformation in Ni–Ti–Fe shape memory alloys at cryogenic temperatures and preliminary results are presented.
Non-Born–Oppenheimer quantum chemistry on the fly with continuous path branching due to nonadiabatic and intense optical interactions
Authors: Yonehara Takehiro , Takatsuka Kazuo
Published: June 2010

We extend our formerly proposed theory for non-Born–Oppenheimer electronic and nuclear wavepacket dynamics within on-the-fly scheme [T. Yonehara, S. Takahashi, and K. Takatsuka, J. Chem. Phys. 130, 214113 (2009)] to a case of nonadiabatic dynamics under an intense laser field: electron wavepacket in a molecule is propagated in attosecond time-scale along non-Born–Oppenheimer nuclear paths that smoothly branch due to nonadiabatic coupling and/or optical interactions. Such branching paths are determined consistently with the motion of the electron wavepackets. Furthermore, these nuclear paths are quantized in terms of Gaussian wavepackets (action decomposed function), which can be applied to nonclassical paths. Both electronic wavepacket dynamics and quantization of non-Born–Oppenheimer paths are generalized so as to include the direct effects of the classical vector potential of electromagnetic fields. In the second half of this paper, we perform numerical studies to explore nonadiabatic dynamics in a laser field by examining two cases: one is a two-state model system having an avoided crossing, and the other is two-state dynamics in HF molecule on the two low lying ab initio potential curves. Both are placed in laser fields. With the former system, we survey some basic properties of the coupling of nonadiabatic dynamics and laser interaction varying the relevant coupling parameters such as the laser timing with respect to the incident of nonadiabatic transition. This investigation will set a foundation for the future studies of control of electronic states in realistic multidimensional molecular systems. Application to the latter system shows that non-Born–Oppenheimer quantum chemistry in laser fields is indeed useful in the study of dynamics in ab initio level. Through the comparison with full quantum data, we verify that the formalism and methodology developed here work accurately. Furthermore, we attain some basic insight about the characteristics of molecules in laser fields.
Note: Three-omega method to measure thermal properties of subnanoliter liquid samples
Authors: Park Byoung Kyoo , Park Jaesung , Kim Dongsik
Published: June 2010

There are growing needs to measure the thermal properties of small-volume liquid samples in various fields of bioengineering and microfluidics. Accordingly, there have been efforts toward miniaturization of the sensing device without substantially sacrificing the sensitivity. The minimum sample volume required for quantitative thermal analysis is currently in the 10 nl scale. In this work, we describe microfabricated sensors and a modified three-omega data-analysis scheme to determine the thermal conductivity k and volumetric heat capacity ρcp of samples of a few hundred picoliters. In experiments using several reference liquids, the technique measured k and ρcp of 750 and 375 pl samples. The measurement accuracies were ∼10% for k and ∼15% for ρcp.
High performance optical absorber based on a plasmonic metamaterial
Authors: Hao Jiaming , Wang Jing , Liu Xianliang , Padilla Willie J. , Zhou Lei , Qiu Min
Published: June 2010

High absorption efficiency is particularly desirable at present for various microtechnological applications including microbolometers, photodectors, coherent thermal emitters, and solar cells. Here we report the design, characterization, and experimental demonstration of an ultrathin, wide-angle, subwavelength high performance metamaterial absorber for optical frequencies. Experimental results show that an absorption peak of 88% is achieved at the wavelength of ∼1.58 μm, though theoretical results give near perfect absorption.
Thermomechanical control of electronic coupling in quantum dot solids
Authors: Zhang Jianhong , Lutich Andrey A. , Susha Andrei S. , Döblinger Markus , Mauser Christian , Govorov Alexander O. , Rogach Andrey L. , Jäckel Frank , Feldmann Jochen
Published: June 2010

We show that electronic coupling in quantum dot solids can be controlled thermomechanically. The amount and nature of interstitial material controls the shrinkage of the solids upon cooling and thereby the distances as well as electronic coupling between the constituting semiconductor nanocrystals. Using photoluminescence and transmission electron microscopy at variable temperatures we apply this concept to single nanowires and densely packed nanocrystals. We tune the band gap emission and realize both temperature-induced red- and blueshifts.
A path-integral Monte Carlo study of a small cluster: The Ar trimer
Authors: Pérez de Tudela R. , Márquez-Mijares M. , González-Lezana T. , Roncero O. , Miret-Artés S. , Delgado-Barrio G. , Villarreal P.
Published: June 2010

The Ar3 system has been studied between T=0 K and T=40 K by means of a path-integral Monte Carlo (PIMC) method. The behavior of the average energy in terms of the temperature has been explained by comparison with results obtained with the thermal averaged rovibrational spectra estimated via: (i) a quantum mechanical method based on distributed Gaussian functions for the interparticle distances and (ii) an analytical model which precisely accounts for the participation of the dissociative continua Ar2+Ar and Ar+Ar+Ar. Beyond T∼20 K, the system explores floppier configurations than the rigid equilateral geometry, as linear and Ar–Ar2-like arrangements, and fragmentates around T∼40 K. A careful investigation of the specific heat in terms of a confining radius in the PIMC calculation seems to discard a proper phase transition as in larger clusters, in apparent contradiction with previous reports of precise values for a liquid-gas transition. The onset of this noticeable change in the dynamics of the trimer occurs, however, at a remarkably low value of the temperature in comparison with Arn systems formed with more Ar atoms. Quantum mechanical effects are found of relevance at T≤15 K, with both energies and radial distributions obtained with a quantum PIMC deviating from the corresponding classical results, thus precluding exclusively classical approaches for a precise description of the system at this low temperature range.
Annealing effects on a high-k lanthanum oxide film on Si (001) analyzed by aberration-corrected transmission electron microscopy/scanning transmission electron microscopy and electron energy loss spectroscopy
Authors: Inamoto S. , Yamasaki J. , Okunishi E. , Kakushima K. , Iwai H. , Tanaka N.
Published: June 2010

The annealing behavior of a lanthanum oxide thin film deposited on a silicon (001) substrate by electron-beam evaporation has been studied by aberration-corrected transmission electron microscopy (TEM), scanning TEM (STEM), and electron energy loss spectroscopy (EELS). We have developed a procedure for the precise measurement of thickness and interfacial roughness by taking advantage of features of aberration correction combined with the statistics of fluctuating crystalline edge positions. The results of the measurements and quantitative elemental analyses by STEM-EELS have revealed atomic diffusion and reactions during deposition and postdeposition annealing (PDA) at 300 and 500 °C. The channel mobility could be limited by Coulomb scattering before PDA, and by remote roughness scattering and remote phonon scattering after PDA at 500 °C. When we consider the large leakage current caused by oxygen defects in the as-deposited sample and the large equivalent oxide thickness of the thick Si-rich layer in the 500 °C-PDA sample, the gate properties of the 300 °C-PDA sample should be better than those of other samples, as shown by electrical measurements.
Low frequency hysteresis loops of superparamagnetic nanoparticles with uniaxial anisotropy
Authors: Usov N. A.
Published: June 2010

The low frequency hysteresis loops of superparamagnetic nanoparticles with uniaxial anisotropy are calculated as a function of the particle diameter, alternating magnetic field amplitude H0, frequency, and particle magnetic parameters both for oriented and nonoriented assemblies. The magnetic field frequency is assumed so high, f>50–100 kHz, that the mechanical rotation of a particle in surrounding medium is restricted. Thus, only the Neel–Brown magnetization relaxation process is taken into account. Pronounced dependence of the specific loss power on the particle diameter is found in the linear regime pertaining to small magnetic field amplitudes. For an oriented assembly of Co nanoparticles with optimal diameter D≈6 nm the specific power loss can be as high as 1600 W/g for typical values H0=200 Oe and f=500 kHz. It is three times less for the corresponding nonoriented assembly. Nevertheless, using of particles with low anisotropy field, i.e., particles of soft magnetic type, seems to be preferable for the purpose of magnetic nanoparticle hyperthermia. For such an assembly the nonlinear regime can be easily accessed. Hence the hysteresis loop area increases and is comparable with its maximum possible value.
Formation of edge misfit dislocations in GexSi1−x(x∼0.4–0.8) films grown on misoriented (001)→(111) Si substrates: Features before and after film annealing
Authors: Bolkhovityanov Yu. B. , Deryabin A. S. , Gutakovskii A. K. , Sokolov L. V.
Published: June 2010

The dislocation structure at the initial stage of relaxation of GexSi1−x films (x∼0.4–0.8) grown on Si(001) substrates tilted at 6° to the nearest (111) plane is studied. One of the directions along which edge dislocations are formed is no longer in the plane of the interface but crosses the latter at the angle of miscut. Therefore, long edge misfit dislocations (MDs) cannot exist in the direction of substrate misorientation, because their ends move away from the interface during dislocation propagation. Two different mechanisms of formation of short segments of edge (90°) MDs in the direction of substrate misorientation are found. The first mechanism is the correlated nucleation of complementary 60° dislocation half-loops manifested in the form of the so-called Y-center consisting of a short segment of the 90° MD and 60° MDs diverging from this segment in form of two rays in the miscut direction. In the second mechanism, the 90° MD segment is formed owing to intersection of already existing complementary 60° MDs slipping in mirrorlike inclined planes {111}. Samples annealed at higher temperatures contain MD segments, which lose their contrast on one of the TEM images taken to detect edge dislocation segments in the two-wave diffraction mode but do not coincide with the direction [110] (they pass along the intersections of the mirrorlike inclined planes {111} with the surface of the misoriented Si substrate). To explain this phenomenon, a model is proposed, where one of the pair of complementary 60° MDs propagating at an angle to each other continuously approaches the other by the cross-slip mechanism. Formation of a chain of edge MD segments connected by a pair of 60° MDs becomes possible. The averaged direction of such a dislocation structure coincides with the direction of one of the 60° MDs.
Development of an atmospheric-pressure homogeneous and cold Ar/O2 plasma source operating in glow discharge
Authors: Li Shou-Zhe , Wu Qi , Zhang Jialiang , Wang Dezhen , Uhm Han S.
Published: June 2010

An atmospheric-pressure Ar/O2 glow discharge is generated in a parallel bare metal plate reactor with a radio-frequency power supply by introducing a dielectric strip in the inlet of the gas flow. The role of the dielectric strip is discussed experimentally. The allowable oxygen-to-argon ratio reaches 1.0 vol % and the generated Ar/O2 plasma discharge is characterized by a low gas temperature and good spatial homogeneity, implying its feasible application as a type of material treatment for a large-area surface, as illustrated experimentally by the ashing of carbon black.
Ice crystallization in water’s “no-man’s land”
Authors: Moore Emily B. , Molinero Valeria
Published: June 2010

The crystallization of water at 180 K is studied through large-scale molecular dynamics simulations with the monatomic water model mW. This temperature is in the middle of water’s “no-man’s land,” where rapid ice crystallization prevents the elucidation of the structure of liquid water and its transformation into ice with state of the art experimental methods. We find that critical ice nuclei (that contain less than ten water molecules) form in a time scale shorter than the time required for the relaxation of the liquid, suggesting that supercooled liquid water cannot be properly equilibrated in this region. We distinguish three stages in the crystallization of water at 180 K: concurrent nucleation and growth of ice, followed by consolidation that decreases the number density of ice nuclei, and finally, slow growth of the crystallites without change in their number density. The kinetics of the transformation along the three stages is well described by a single compacted exponential Avrami equation with n≈1.7. This work confirms the coexistence of ice and liquid after water is crystallized in “no-man’s land”: the formation of ice plateaus when there is still 15%–20% of liquid water in the systems, thinly dispersed between ice I crystals with linear dimensions ranging from 3 to 10 nm. We speculate that the nanoscopic size of the crystallites decreases their melting point and slows their evolution toward the thermodynamically most stable fully crystalline state.
Optical properties of InGaN quantum dots in monolithic pillar microcavities
Authors: Sebald K. , Seyfried M. , Kalden J. , Gutowski J. , Dartsch H. , Tessarek C. , Aschenbrenner T. , Figge S. , Kruse C. , Hommel D. , Florian M. , Jahnke F.
Published: June 2010

The integration of InGaN quantum dots into GaN-based monolithic microcavities grown by metal-organic vapor-phase epitaxy is demonstrated. Microphotoluminescence spectra reveal distinct spectrally sharp emission lines around 2.73 eV, which can be attributed to the emission of single InGaN quantum dots. The samples are structured into airpost pillar microcavities. The longitudinal and transversal mode spectra of these cavities are in good agreement with theoretical calculations based on a vectorial transfer-matrix method. Quality factors up to Q=280 have been achieved.
Electric field: A catalyst for hydrogenation of graphene
Authors: Ao Z. M. , Peeters F. M.
Published: June 2010

Due to the importance of hydrogenation of graphene for several applications, we present an alternative approach to hydrogenate graphene based on density functional theory calculations. We find that a negative perpendicular electric field F can act as a catalyst to reduce the energy barrier for molecular H2 dissociative adsorption on graphene. Increasing −F above 0.02 a.u. (1 a.u.=5.14×1011 V/m), this hydrogenation process occurs smoothly without any potential barrier.
Time-resolved analysis of catastrophic optical damage in 975 nm emitting diode lasers
Authors: Hempel Martin , Ziegler Mathias , Tomm Jens W. , Elsaesser Thomas , Michel Nicolas , Krakowski Michel
Published: June 2010

Catastrophic optical damage (COD) is analyzed during single current pulse excitation of 975 nm emitting diode lasers. Power transients and thermal images are monitored during each pulse. The COD process is unambiguously related to the occurrence of a “thermal flash” of Planck’s radiation. We observe COD to ignite multiple times in subsequent pulses. Thermography allows for tracing a spatial motion of the COD site on the front facet of the devices. The time constant of power decay after the onset of COD has values from 400 to 2000 ns, i.e., an order of magnitude longer than observed for shorter-wavelength devices.
Hydrogen–dopant interactions in SiGe and strained Si
Authors: Tsetseris L. , Fleetwood D. M. , Schrimpf R. D. , Pantelides S. T.
Published: June 2010

The appearance of carrier traps and the deactivation of dopants are typical hydrogen-related phenomena that are of prime importance to the reliability of traditional Si-based devices. Here we probe with first-principles calculations, the dynamics of hydrogen as individual impurities or in complexes with dopants in strained Si (s-Si) and SiGe systems. We find that the charged state determines the tendency of hydrogen to be released from dopant sites and to shuttle between a SiGe substrate and a s-Si overlayer. In this way, the effect of hydrogen differs between accumulation and inversion cycles of s-Si and SiGe devices.
Core-shell gold J-aggregate nanoparticles for highly efficient strong coupling applications
Authors: Djoumessi Lekeufack Diane , Brioude Arnaud , Coleman Anthony W. , Miele Philippe , Bellessa Joel , De Zeng Li , Stadelmann Pierre
Published: June 2010

We have developed a straightforward synthetic route to prepare core-shell systems based on gold nanoparticles (NPs) surrounded with J-aggregates molecules. This synthesis allows the direct and efficient coating, at room temperature, of pretreated citrate-stabilized gold NPs with 5, 5′, 6, 6′-tetrachloro-1-1′-diethyl-3, 3′-di (4-sulfobutyl)-benzimidazolocarbocyanine (TDBC), without supplementary adding of salts and bases during the synthesis. As the size of gold particle is tunable, the precise optimization of the strong coupling between the electronic transitions of organic components (TDBC) and the plasmon modes of the gold NPs is achieved corresponding to a Rabi energy of 220 meV, a value not yet obtained in such a system.
Theoretical investigation on the chemical sensing of metalloporphyrin-based molecular junction
Authors: Liu Hongmei , Xu Zhong , Wang Nan , Yu Cui , Gao Nengyue , Zhao Jianwei , Li Ning
Published: June 2010

Following the previous study [N. Wang et al., J. Phys. Chem. C 113, 7416 (2009)] which focused on specific electron transport pathway in the cyclic molecules, we investigated the chemical sensing of the metalloporphyrin-based molecular junctions. Theoretical calculations have been carried out using density functional theory combined with the nonequilibrium Green’s function method. The adsorbed molecules (CO, NO, and O2) show diverse effects which depend on the connecting position between the metalloporphyrin with the electrodes. For iron (II) porphyrin (FeP) and manganese (II) porphyrin (MnP) connected at the 9,11-position (P-connection), the electron only passes through the porphyrin ring and the binding of ligand has no effect on the molecular conductivity. However, for the FeP and MnP connected at the 1,5-position (D-connection), the molecular conductivity decreases dramatically after adsorptions of three diatomic molecules as a result of the electron takes the path through the metallic center. For the potential application of chemical sensing, the selectivities of the FeP and MnP are discussed as well.
Observation of full shot noise in CoFeB/MgO/CoFeB-based magnetic tunneling junctions
Authors: Sekiguchi K. , Arakawa T. , Yamauchi Y. , Chida K. , Yamada M. , Takahashi H. , Chiba D. , Kobayashi K. , Ono T.
Published: June 2010

The electron transport through the CoFeB/MgO/CoFeB-based magnetic tunneling junction (MTJ) was studied by the shot noise measurement. The obtained Fano factor to characterize the shot noise is very close to unity, indicating the full shot noise, namely, the shot noise in the Schottky limit, both in the parallel and antiparallel magnetization configurations. This means the Poissonian process of the electron tunneling and the absence of the electron–electron correlation in the low bias regime. The shot noise measurements will be a good guideline to make up tunneling criteria for designing MTJ-based spin devices.
Temperature dependence of electron concentration and mobility in n-GaN measured up to 1020 K
Authors: Tokuda H. , Kodama K. , Kuzuhara M.
Published: June 2010

Temperature dependence of Hall electron concentration and mobility in n-GaN has been measured up to 1020 K. The electron concentration increased monotonically with temperature and did not saturate. The measured values were fitted with the calculated ones for the whole temperature range. It is found that following two assumptions have to be made in order to obtain the best fit for both electron concentration and mobility: (i) two donor levels and one acceptor level (including dislocation) have to be taken into account; and (ii) one donor level lies in the conduction band. The obtained results in this study will contribute to the design of GaN devices operating at high temperatures.
Natural radioactivity consideration for high-κ dielectrics and metal gates choice in nanoelectronic devices
Authors: Gedion Michael , Wrobel Frédéric , Saigné Frédéric
Published: June 2010

In order to face downscaling, new chemical elements are used and suggested for the semiconductor industry. However, some of these elements have natural radioactive isotopes, which may cause reliability issues in nanoelectronic devices by triggering soft errors. In this paper, we focus on high-κ dielectric materials and metal gates. We show that besides physical, chemical and mechanical properties of high-κ dielectrics and metal gates, natural radioactivity is also a crucial property to be considered in order to select suitable materials. Using samarium in gate oxides and platinum in electrodes turns out to be a crucial issue for ground level applications.
Synthesis and characterization of TiO
2 photocatalyst doped by transition metal ions (Fe
3+, Cr
3+ and V
5+)
Authors: Tuan Vu Anh , Tuan Nguyen Quoc , Linh Bui Thi Hai , Cuong Tran Manh , Phuong Dang Tuyet , Hoa Tran Thi Kim
Published: June 2010

Nano TiO
2 was synthesized by the hydrothermal method. The sample was doped with transition metal ions (V, Cr and Fe) and non-metal (N). Doped TiO
2 samples were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis). Photocatalytic activity in the mineralization of xylene (vapor phase), methylene blue and active dyer PR (liquid phase) was tested. In comparison with non-doped TiO
2, V-, Cr-, Fe-doped TiO
2 and N-doped TiO
2 samples exhibited much higher photocatalytic activity using visible light instead of UV.
Multipliers on compact groups
Authors: Dunkl Charles F. , Ramirez Donald E.
Published: June 2010

Let a compact group

G
G

act continuously both by left and right translation on a Banach space

V
V

of integrable functions on

G
G

. Then

M

(
V
)

\mathfrak {M}(V)

, the space of bounded linear operators on

V
V

commuting with right translation, contains a homomorphic image of

L
1

(
G
)

{L^1}(G)

, whose closure is exactly the set of operators on which

G
G

acts continuously. Further, this set is exactly the ideal of compact operators in

M

(
V
)

\mathfrak {M}(V)

. A restricted version holds for noncompact groups.
Hyperbolicity of a complex manifold and other equivalent properties
Authors: Hahn Kyong T. , Kim Kang T.
Published: June 2010

Defining the notions of Schottky, Landau and Picard properties on a plane domain, the first author [3] proved that a domain in

C

{\mathbf {C}}

having any of these properties is equivalent to the hyperbolicity of the domain. In this paper the authors extend these notions to higher-dimensional case and obtain other various equivalent conditions for the hyperbolicity of a complex manifold.
A chaotic function possessing a scrambled set with positive Lebesgue measure
Authors: Kan I.
Published: June 2010

A continuous function, chaotic in the sense of Li and Yorke, is constructed which possesses a scrambled set of positive Lebesgue measure.
A note on invariant finitely additive measures
Authors: Dani S. G.
Published: June 2010

We show that under certain general conditions any finitely additive measure which is defined for all subsets of a set

X
X

and is invariant under the action of a group

G
G

acting on

X
X

is concentrated on a

G
G

-invariant subset

Y
Y

on which the

G
G

-action factors to that of an amenable group. The result is then applied to prove a conjecture of

S
S

. Wagon about finitely additive measures on spheres.
Mean exit time of a diffusion process from a small sphere
Authors: Pinsky Mark A.
Published: June 2010

The first two nonzero terms in the asymptotic expansion of the mean exit time from a small sphere are expressed in terms of the radius, the scalar curvature of the Riemannian metric and the vector field which defines the drift in the infinitesimal generator.
A characterization of free abelian groups
Authors: Steprāns Juris
Published: June 2010

In the category of abelian groups, being free is equivalent to having a discrete norm.
A simple construction of genus fields of abelian number fields
Authors: Zhang Xian Ke
Published: June 2010

Simple elementary construction of the genus field

K
∗

{K^ * }

(= maximal abelian subfield of the Hilbert class field) of any abelian number field

K
K

is given without using class field theory. When

K
K

is of type

(
l
,
…
,
l
)

(l, \ldots ,l)

with

l
l

prime, the construction is more explicit. These results contain some former results and show that the main result in [8] has mistakes.
Minimum eigenvalues for positive, Rockland operators
Authors: Hulanicki A. , Jenkins J. W. , Ludwig J.
Published: June 2010

Let

L
L

be a positive, Rockland operator of homogeneous degree

γ
\gamma

. The minimum eigenvalue of

d
π
(
L
)

d\pi (L)

increases as the

γ
\gamma

th power of the homogeneous distance from the origin of the orbit corresponding to

π
\pi

.
On the elliptic equation 𝐷ᵢ[𝑎ᵢⱼ(𝑥)𝐷ⱼ𝑈]-𝑘(𝑥)𝑈+𝐾(𝑥)𝑈^{𝑝}=0
Authors: Lin Fang-Hua
Published: June 2010

The problem of the existence and nonexistence of entire, positive solutions to the uniformly elliptic, semilinear equation
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper D Subscript i Baseline left-bracket a Subscript i j Baseline left-parenthesis x right-parenthesis upper D Subscript j Baseline upper U right-bracket minus k left-parenthesis x right-parenthesis upper U plus upper K left-parenthesis x right-parenthesis upper U Superscript p Baseline equals 0">

D
i

[

a

i
j

(
x
)

D
j

U
]
−
k
(
x
)
U
+
K
(
x
)

U
p

=
0

{D_i}[{a_{ij}}(x){D_j}U] - k(x)U + K(x){U^p} = 0

in

R

n

{{\mathbf {R}}^n}

, where

p
>
1

p > 1

, is studied. A limiting case when

K
(
x
)

K(x)

is negative and has quadratic decay at infinity is also treated.
On a 2-dimensional Einstein Kaehler submanifold of a complex space form
Authors: Matsuyama Yoshio
Published: June 2010

In this paper we consider when a Kaehler submanifold of a complex space form is Einstein with respect to the induced metric. Then we shall show that (1) a

2
2

-dimensional complete Kaehler submanifold

M
M

of a

4
4

-dimensional complex projective space

P
4

(
C
)

{P^4}\left ( C \right )

is Einstein if and only if

M
M

is holomorphically isometric to

P
2

(
C
)

{P^2}\left ( C \right )

which is totally geodesic in

P
4

(
C
)

{P^4}\left ( C \right )

or a hyperquadric

Q
2

(
C
)

{Q^2}\left ( C \right )

in

P
3

(
C
)

{P^3}\left ( C \right )

which is totally geodesic in

P
4

(
C
)

{P^4}\left ( C \right )

, and that (2) if

M
M

is a

2
2

-dimensional Einstein Kaehler submanifold of a

4
4

-dimensional complex space form

M
~

4

(

c
~

)

{\tilde M^4}\left ( {\tilde c} \right )

of nonpositive constant holomorphic sectional curvature

c
~

\tilde c

, then

M
M

is totally geodesic.
Immersions of 𝑛-manifolds into (2𝑛-2)-manifolds
Authors: Li B. H. , Peterson F. P.
Published: June 2010

We study the question of when a map from

M
n

{M^n}

to

N

2
n
−
2

{N^{2n - 2}}

is homotopic to an immersion.
A universal exhausting domain
Authors: Fridman B. L.
Published: June 2010

A bounded domain

D
⊂

C

n

D \subset {{\mathbf {C}}^n}

is constructed such that every domain

G
⊂

C

n

G \subset {{\mathbf {C}}^n}

is a monotone union of biholomorphic images of

D
D

.
Concerning continuity apart from a meager set
Authors: Kaniewski Janusz , Piotrowski Zbigniew
Published: June 2010

Given a

σ
\sigma

-ideal

J

\mathcal {J}

of subsets of a space

X
X

, mappings

f
:
X
→
Y

f:X \to Y

are investigated, such that

f

|

X
0

f|{X_0}

is continuous for some closed

X
0

⊂
X

{X_0} \subset X

with

X
∖

X
0

∈

J

X\backslash {X_0} \in \mathcal {J}

.
Baker functions for compact Riemann surfaces
Authors: Schilling R. J.
Published: June 2010

This article contains a proof of an important theorem in soliton mathematics. The theorem, stated roughly in [4], contains necessary conditions for the existence of a vector function
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="psi left-parenthesis t comma p right-parenthesis equals left-parenthesis psi 1 left-parenthesis t comma p right-parenthesis comma ellipsis comma psi Subscript l Baseline left-parenthesis t comma p right-parenthesis right-parenthesis comma t element-of bold upper C Superscript g Baseline comma p element-of upper R comma">

ψ
(
t
,
p
)
=
(

ψ
1

(
t
,
p
)
,
…
,

ψ
l

(
t
,
p
)
)
,

t
∈

C

g

,

p
∈
R
,

\psi (t,p) = ({\psi _1}(t,p), \ldots ,{\psi _l}(t,p)),\quad t \in {{\mathbf {C}}^g},\quad p \in R,

\]
with prescribed poles and

l
l

essential singularities an a compact Riemann surface

R
R

of genus

g
g

.

ψ
\psi

is called a Baker function in honor of the 1928 article [1] of H. F. Baker. This report clarifies Krichever’s description of

ψ
\psi

for

l
>
1

l > 1

essential singularities. The divisors

δ
α

{\delta _\alpha }

in (1) below are the key to the

l
>
1

l > 1

construction. Krichever’s

(
l
>
1
)

(l > 1)

construction is not easy to deal with in practical problems. E. Previato [5] noted this and applied our characterization of the

δ
α

{\delta _\alpha }

to construct the finite gap solutions to the nonlinear Schroedinger equation.