bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a whole-cell biocatalyst with NADPH regeneration system for biosulfoxidation
Authors: Zhai Xiao-Hong , Ma Yuan-Hui , Lai Dun-Yue , Zhou Shuo , Chen Zhen-Ming
Published: June 2013

A formate dehydrogenase gene (fdh) originated from Candida boidinii was co-expressed in E. coli BL21 (DE3) with the cyclohexanone monooxygenase gene (chmo) cloned from Acinetobacter calcoaceticus NCIMB 9871. The co-expression system was then used as a whole-cell biocatalyst to synthesize chiral phenyl methyl sulfoxide (PMSO) from thioanisole (PMS) and the reaction conditions were investigated. When the initial concentration of PMS was 20 mM, the specific productivity of PMSO in this system was 2.07 μmol g−1 cw min−1 (cw: wet cell weight) and the ee value for the R-sulfoxide was 99 %. In contrast, when chmo was the only gene expressed in E. coli, the specific productivity of PMSO was 0.053 μmol g−1 cw min−1 with no exact enantioselectivity. Further determination of NADPH concentration in the whole-cell catalysts suggested that co-expression of fdh with chmo significantly improved NADPH supply. Thus, this whole-cell biocatalyst system is highly advantageous for the synthesis of optically pure R-sulfoxide.
Views of Genetics Health Professionals on the Return of Genomic Results
Authors: Grove Megan E. , Wolpert Maya N. , Cho Mildred K. , Lee Sandra Soo‐Jin , Ormond Kelly E.
Published: June 2013

As exome and whole genome sequencing become clinically available, the potential to receive a large number of clinically relevant but incidental results is a significant challenge in the provision of genomic counseling. We conducted three focus groups of a total of 35 individuals who were members of ASHG and/or NSGC, assessing views towards the return of genomic results. Participants stressed that patient autonomy was primary. There was consensus that a mechanism to return results to the healthcare provider, rather than patient, and to streamline integration into the electronic health record would ensure these results had the maximal impact on patient management. All three focus groups agreed that pharmacogenomic results were reasonable to return and that they were not felt to be stigmatizing. With regard to the return of medically relevant results, there was much debate. Participants had difficulty in consistently assigning specific diseases to ‘bins’ that were considered obligatory versus optional for disclosure. Consensus was reached regarding the importance of informed consent and pretest counseling visits to clarify what the return of results process would entail. Evidence based professional guidelines should continue to be developed and regularly revised to assist in consistently and appropriately providing genomic results to patients.
Dipalmitoyl‐Phosphatidylcholine Biosynthesis is Induced by Non‐Injurious Mechanical Stretch in a Model of Alveolar Type II Cells
Authors: Pantazi Despoina , Kitsiouli Eirini , Karkabounas Athanasios , Trangas Theoni , Nakos George , Lekka Marilena E.
Published: June 2013

Dipalmitoylphosphatidylcholine, (DP‐PtdCho), the major phospholipid component of lung surfactant is biosynthesized via a de novo pathway, the last step of which is catalyzed by CDP‐choline:cholinephosphotransferase (CPT) and two remodeling steps: a deacylation and a reacylation one, catalyzed by an acidic, Ca2+‐independent phospholipase A2 (aiPLA2) and a lyso‐phosphatidylcholine acyltransferase (LPCAT), respectively. The aim of our study was to investigate whether a low magnitude, non‐injurious static mode of mechanical stretch can induce phosphatidylcholine (PtdCho) biosynthesis and its remodeling to DP‐PtdCho in the A549 cell‐line, a model of alveolar type II cells. The deformation of A549 cells did not cause any release of lactate dehydrogenase, or phospholipids into the cell culture supernatants. An increase in PtdCho levels was observed after 1 h of static stretching, especially among the DP‐PtdCho molecular species, as indicated by targeted lipidomics approach and site‐directed fatty acyl‐chain analysis. Moreover, although sphingomyelin (CerPCho) levels were unaffected, the DP‐PtdCho/CerPCho ratio increased. Induction was observed in CPT, LPCAT and aiPLA2 enzymatic activities and gene expression. Finally, incubation of the cells with MJ33 suppressed aiPLA2 activity and DP‐PtdCho production. Our data suggest that mild static mechanical stretch can promote the biosynthesis of PtdCho and its remodeling to DP‐PtdCho in lung epithelial cells. Thus, low magnitude stretch could contribute to protective mechanisms rather than to injurious ones.
AtCSP1 regulates germination timing promoted by low temperature
Authors: Yang Yongil , Karlson Dale
Published: June 2013

An Arabidopsis gene trap line (GT606), which disrupted the AtCSP1 gene, exhibited an early germination phenotype that was affected by stratification treatment. Comparative analysis of GUS expression in seeds at the early germination stage, with or without stratification, demonstrated that AtCSP1 expression was affected by cold temperature. Evaluation of germination assays with varying concentrations of ABA or NaCl revealed a reduced sensitivity of the atcsp1 mutant to both ABA and NaCl. Taken together, these data support the hypothesis that AtCSP1 affects early stages of seed germination subsequent to stratification treatment of seeds.
Chronic Suppurative Osteomyelitis of Mandible: A Case Report
Authors: Mehra Hemant , Gupta Sumit , Gupta Hemant , Sinha V. , Singh Jasmeet
Published: June 2013

Osteomyelitis is an inflammatory disease of the bone that usually begins as an infection of the medullary cavity, rapidly involves the haversian system, and quickly extends to the periosteum of the area. It develops in the jaws after a chronic odontogenic infection or for a variety of other reasons such as trauma, inadequate treatment of fracture, or irradiation to the mandible. When antimicrobial agents or drainage prove unsuccessful, acute osteomyelitis may become chronic. Conventional radiography, culture, bone biopsy, radioisotope bone scan, laser Doppler flowmetry, computed tomography, and magnetic resonance imaging are used for its diagnosis. We present a case of chronic suppurative osteomyelitis associated with a draining extraoral sinus, which was successfully treated with surgical debridement and stabilization with a 10-hole reconstruction plate and bicortical screws using AO principles.
Combined Orbital Floor and Medial Wall Fractures Involving the Inferomedial Strut: Repair Technique and Case Series Using Preshaped Porous Polyethylene/Titanium Implants
Authors: Cho Raymond I. , Davies Brett W.
Published: June 2013

Background

Combined orbital floor and medial wall fractures can be technically challenging to repair, particularly when the inferomedial strut is involved. A surgical repair technique is described utilizing a single preshaped porous polyethylene/titanium implant to span both defects.

Methods

Retrospective interventional case series.

Results

Fracture repair was performed on 17 orbits (16 patients) between October 2009 and February 2012. Subsequent surgical revision was required in three cases (18%). Visual acuity was stable or improved in all cases. Of 7 patients with preoperative diplopia, 5 improved and 2 remained stable postoperatively, and there were no cases of new or worsened diplopia following surgery. Postoperative asymmetry in Hertel exophthalmometry averaged 1.0 mm (range 0 to 2 mm). Preoperatively, average orbital volume was 122.7% compared with control (range 109 to 147%, standard deviation [SD] 9.6), which improved to 100.3% postoperatively (range 92 to 110%, SD 5.7). The average decrease in orbital volume was 22.5% (range 10 to 54%, SD 11.4, p < 0.001).

Conclusions

With careful preoperative planning and meticulous surgical technique, combined orbital floor and medial wall fractures involving the inferomedial strut can be successfully repaired with a preshaped porous polyethylene/titanium implant through a transconjunctival/transcaruncular approach with inferior oblique disinsertion.
On almost surely bounded semigroups of random linear operators
Authors: Zhang Xia , Liu Ming
Published: June 2013

Menger proposed transferring the probabilistic notions of quantum mechanics to the underlying geometry. Following Menger's idea, the notion of random metric spaces is a random generalization of that of metric spaces and also plays an important role in the study of random operator equations. The main difficulty of this article is to work out a skill to give a property peculiar to a special semigroup of random operators, which is not involved in the classical case. Subsequently, some random operators equations are studied, in particular, we discuss the Schrödinger-type random equation, which considerably generalizes the corresponding result in the sense of Skorohod.
On the subsystem formulation of linear-response time-dependent DFT
Authors: Pavanello Michele
Published: June 2013

A new and thorough derivation of linear-response subsystem time-dependent density functional theory (TD-DFT) is presented and analyzed in detail. Two equivalent derivations are presented and naturally yield self-consistent subsystem TD-DFT equations. One reduces to the subsystem TD-DFT formalism of Neugebauer [J. Chem. Phys. 126, 134116 (2007)10.1063/1.2713754]. The other yields Dyson type equations involving three types of subsystem response functions: coupled, uncoupled, and Kohn–Sham. The Dyson type equations for subsystem TD-DFT are derived here for the first time. The response function formalism reveals previously hidden qualities and complications of subsystem TD-DFT compared with the regular TD-DFT of the supersystem. For example, analysis of the pole structure of the subsystem response functions shows that each function contains information about the electronic spectrum of the entire supersystem. In addition, comparison of the subsystem and supersystem response functions shows that, while the correlated response is subsystem additive, the Kohn–Sham response is not. Comparison with the non-subjective partition DFT theory shows that this non-additivity is largely an artifact introduced by the subjective nature of the density partitioning in subsystem DFT.
Classification and sound generation of two-dimensional interaction of two Taylor vortices
Authors: Zhang Shuhai , Li Hu , Liu Xuliang , Zhang Hanxin , Shu Chi-Wang
Published: June 2013

Two-dimensional interaction between two Taylor vortices is simulated systematically through solving the two-dimensional, unsteady compressible Navier-Stokes equations using a fifth order weighted essentially nonoscillatory finite difference scheme. The main purpose of this study is to reveal the mechanism of sound generation in two-dimensional interaction of two Taylor vortices. Based on an extensive parameter study on the evolution of the vorticity field, we classify the interaction of two Taylor vortices into four types. The first type is the interaction of two counter-rotating vortices with similar strengths. The second type is the interaction of two co-rotating vortices without merging. The third type is the merging of two co-rotating vortices. The fourth type is the interaction of two vortices with a large difference in their strengths or scales. The mechanism of sound generation is analyzed.
Eigenvalues of normalized Laplacian matrices of fractal trees and dendrimers: Analytical results and applications
Authors: Julaiti Alafate , Wu Bin , Zhang Zhongzhi
Published: June 2013

The eigenvalues of the normalized Laplacian matrix of a network play an important role in its structural and dynamical aspects associated with the network. In this paper, we study the spectra and their applications of normalized Laplacian matrices of a family of fractal trees and dendrimers modeled by Cayley trees, both of which are built in an iterative way. For the fractal trees, we apply the spectral decimation approach to determine analytically all the eigenvalues and their corresponding multiplicities, with the eigenvalues provided by a recursive relation governing the eigenvalues of networks at two successive generations. For Cayley trees, we show that all their eigenvalues can be obtained by computing the roots of several small-degree polynomials defined recursively. By using the relation between normalized Laplacian spectra and eigentime identity, we derive the explicit solution to the eigentime identity for random walks on the two treelike networks, the leading scalings of which follow quite different behaviors. In addition, we corroborate the obtained eigenvalues and their degeneracies through the link between them and the number of spanning trees.
Assessing the two-body diffusion tensor calculated by the bead models
Authors: Wang Nuo , Huber Gary A. , McCammon J. Andrew
Published: June 2013

The diffusion tensor of complex macromolecules in Stokes flow is often approximated by the bead models. The bead models are known to reproduce the experimental diffusion coefficients of a single macromolecule, but the accuracy of their calculation of the whole multi-body diffusion tensor, which is important for Brownian dynamics simulations, has not been closely investigated. As a first step, we assess the accuracy of the bead model calculated diffusion tensor of two spheres. Our results show that the bead models produce very accurate diffusion tensors for two spheres where a reasonable number of beads are used and there is no bead overlap.
Low temperature phase properties of water confined in mesoporous silica MCM-41: Thermodynamic and neutron scattering study
Authors: Kittaka Shigeharu , Takahara Shuichi , Matsumoto Hideyuki , Wada Yasuki , Satoh Taku J. , Yamaguchi Toshio
Published: June 2013

The phase properties of water confined in mesoporous silica MCM-41 were investigated over a temperature range of 100–298 K as a function of pore size by specific heat capacity and inelastic neutron scattering (INS) measurements. The water content of the samples was carefully controlled to ensure the capillary filled state and no overloading of water. The values of heat capacity of the pore water are higher than those of bulk ice and liquid water over the whole temperature range measured. The contribution of water in the inner part of pores (abbreviated as the internal water) was elucidated by using the heat capacity data of monolayer water measured. The entropy of the internal water was then estimated from integration of the heat capacity of the internal water. The entropy values of the internal water increase by confinement in the pores of MCM-41 in both liquid and frozen regions, indicating an increase in the deformation of the structure and/or a change in the dynamics in both regions. The INS spectra show the density of states for the librational motion of water frozen at 50 K, suggesting that the confined water is similar to amorphous ice rather than to crystalline ice. When the sample is warmed to melt, the band edge of the librational motion for water frozen in large pores (diameter of 3.6 nm) shifts to a lower energy side, indicating the weakening of intermolecular hydrogen bonds. For water in small pores (2.1 nm), on the contrary, the librational band shifts slightly to a higher energy side, suggesting the low density liquid to high density liquid transition (L–L transition) at 225–250 K. A plausible mechanism of the L–L transition of water in confinement is proposed in terms of incomplete growth of homogeneous nucleation of ice due to an interfacial free energy effect to inhibit crystallization of water confined in small pores.
A systematic development of a polarizable potential of water
Authors: Kiss Péter T. , Baranyai András
Published: June 2013

Based on extensive studies of existing potentials we propose a new molecular model for water. The new model is rigid and contains three Gaussian charges. Contrary to other models, all charges take part in the polarization of the molecule. They are connected by harmonic springs to their gas-phase positions: the negative charge to a prescribed point on the main axis of the molecule; the positive charges to the hydrogens. The mechanical equilibrium between the electrostatic forces and the spring forces determines the polarization of the molecule which is established by iteration at every timestep. The model gives excellent estimates for ambient liquid properties and reasonably good results from high-pressure solids to gas-phase clusters. We present a detailed description of the development of this model and a large number of calculated properties compared to the estimates of the nonpolarizable TIP4P/2005 [J. L. F. Abascal and C. Vega, J. Chem. Phys. 123, 234505 (2005)10.1063/1.2121687], the polarizable GCPM [P. Paricaud, M. Predota, A. A. Chialvo, and P. T. Cummings, J. Chem. Phys. 122, 244511 (2005)10.1063/1.1940033], and our earlier BKd3 model [P. T. Kiss and A. Baranyai, J. Chem. Phys. 137, 084506 (2012)10.1063/1.4746419]. The best overall performance is shown by the new model.
Electron attachment to CF3 and CF3Br at temperatures up to 890 K: Experimental test of the kinetic modeling approach
Authors: Shuman Nicholas S. , Miller Thomas M. , Viggiano Albert A. , Troe Jürgen
Published: June 2013

Thermal rate constants and product branching fractions for electron attachment to CF3Br and the CF3 radical have been measured over the temperature range 300–890 K, the upper limit being restricted by thermal decomposition of CF3Br. Both measurements were made in Flowing Afterglow Langmuir Probe apparatuses; the CF3Br measurement was made using standard techniques, and the CF3 measurement using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Attachment to CF3Br proceeds exclusively by the dissociative channel yielding Br−, with a rate constant increasing from 1.1 × 10−8 cm3 s−1 at 300 K to 5.3 × 10−8 cm3 s−1 at 890 K, somewhat lower than previous data at temperatures up to 777 K. CF3 attachment proceeds through competition between associative attachment yielding CF3− and dissociative attachment yielding F−. Prior data up to 600 K showed the rate constant monotonically increasing, with the partial rate constant of the dissociative channel following Arrhenius behavior; however, extrapolation of the data using a recently proposed kinetic modeling approach predicted the rate constant to turn over at higher temperatures, despite being only ∼5% of the collision rate. The current data agree well with the previous kinetic modeling extrapolation, providing a demonstration of the predictive capabilities of the approach.
Matrix isolation ESR spectroscopy and magnetic anisotropy of D3h symmetric septet trinitrenes
Authors: Misochko Eugenii Ya. , Akimov Alexander V. , Masitov Artem A. , Korchagin Denis V. , Aldoshin Sergei M. , Chapyshev Sergei V.
Published: June 2013

The fine-structure (FS) parameters D of a series of D3h symmetric septet trinitrenes were analyzed theoretically using density functional theory (DFT) calculations and compared with the experimental D values derived from ESR spectra. ESR studies show that D3h symmetric septet 1,3,5-trichloro-2,4,6-trinitrenobenzene with D = −0.0957 cm−1 and E = 0 cm−1 is the major paramagnetic product of the photolysis of 1,3,5-triazido-2,4,6-trichlorobenzene in solid argon matrices at 15 K. Trinitrenes of this type display in the powder X-band ESR spectra intense Z1-transition at very low magnetic fields, the position of which allows one to precisely calculate the parameter D of such molecules. Thus, our revision of the FS parameters of well-known 1,3,5-tricyano-2,4,6-trinitrenobenzene [E. Wasserman, K. Schueller, and W. A. Yager, Chem. Phys. Lett. 2, 259 (1968)10.1016/0009-2614(68)85019-5] shows that this trinitrene has |D| = 0.092 cm−1 and E = 0 cm−1. DFT calculations reveal that, unlike C2v symmetric septet trinitrenes, D3h symmetric trinitrenes have the same orientations of the spin-spin coupling tensor $\hat D_{\it SS}$D̂SS and the spin-orbit coupling tensor $\hat D_{\it SOC}$D̂SOC and, as a result, have negative signs for both the DSS and DSOC values. The negative magnetic anisotropy of septet 2,4,6-trinitrenobenzenes is considerably strengthened on introduction of heavy atoms in the molecules, owing to an increase in contributions of various excitation states to the DSOC term.
First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE
Authors: Schmidt H. T. , Thomas R. D. , Gatchell M. , Rosén S. , Reinhed P. , Löfgren P. , Brännholm L. , Blom M. , Björkhage M. , Bäckström E. , Alexander J. D. , Leontein S. , Hanstorp D. , Zettergren H. , Liljeby L. , Källberg A. , Simonsson A. , Hellberg F. , Mannervik S. , Larsson M. , Geppert W. D. , Rensfelt K. G. , Danared H. , Paál A. , Masuda M. , Halldén P. , Andler G. , Stockett M. H. , Chen T. , Källersjö G. , Weimer J. , Hansen K. , Hartman H. , Cederquist H.
Published: June 2013

We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (\documentclass[12pt]{minimal}\begin{document}${\rm C}_n^-$\end{document}Cn−, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV \documentclass[12pt]{minimal}\begin{document}${\rm C}_2^-$\end{document}C2− molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s ± 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10−14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
Compact inline optical electron polarimeter
Authors: Pirbhai M. , Ryan D. M. , Richards G. , Gay T. J.
Published: June 2013

A compact optical electron polarimeter using a helium target is described. It offers a maximum fluorescence detection efficiency of ∼20 Hz/nA, which is an order of magnitude higher than that of earlier designs. With an argon target, this device is expected to have a polarimetric figure-of-merit of 270 Hz/nA. By relying on a magnetic field to guide a longitudinally spin-polarized electron beam, the present instrument employs fewer electrodes. It also uses a commercially available integrated photon counting module. These features allow it to occupy a smaller volume and make it easier to operate.
Nonlocal electron-phonon coupling in organic semiconductor crystals: The role of acoustic lattice vibrations
Authors: Li Yuan , Coropceanu Veaceslav , Brédas Jean-Luc
Published: June 2013

We discuss, in the context of a tight-binding description, how the electronic and charge-transport properties in single crystals of molecular organic semiconductors are affected by the nonlocal electron-phonon coupling to both acoustic and optical lattice vibrations. While the nonlocal electron-phonon interactions can in general be divided into contributions from symmetric modes and antisymmetric modes, we show that only the antisymmetric coupling mechanism is operational in the case of acoustic vibrations. Interestingly, when the quantum nature of the phonons can be neglected, the effect of electron-phonon interactions with acoustic phonons is found to be equivalent to that of the electron-phonon interactions with optical phonons, in the case where contributions from symmetric and antisymmetric modes are equal.
Effect of purity, edge length, and growth area on field emission of multi-walled carbon nanotube emitter arrays
Authors: Shahi Monika , Gautam S. , Shah P. V. , Jha P. , Kumar P. , Rawat J. S. , Chaudhury P. K. , Harsh  , Tandon R. P.
Published: June 2013

Present report aims to study the effect of purity, edge length, and growth area on field emission of patterned carbon nanotube (CNT) emitter arrays. For development of four CNT emitter arrays (CEAs), low resistively silicon substrates were coated with thin film of iron catalyst using photolithography, sputtering, and lift off process. Four CEAs were synthesized on these substrates using thermal chemical vapor deposition with minor changes in pretreatment duration. Out of these, two CEAs have 10 μm × 10 μm and 40 μm × 40 μm solid square dots of CNTs with constant 20 μm inter-dot separation. Other two CEAs have ring square bundles of CNTs and these CEAs are envisioned as 10 μm × 10 μm square dots with 4 μm × 4 μm scooped out area and 15 μm × 15 μm square dots with 5 μm × 5 μm lift out area with constant 20 μm inter-dot spacing. Solid square dot structures have exactly constant edge length per unit area with more than four-fold difference in CNT growth area however ring square dot patterns have minor difference in edge length per unit area with approximately two times difference in CNT growth area. Quality and morphology of synthesized CEAs were assessed by scanning electron microscope and Raman characterization which confirm major differences. Field emission of all CEAs was carried out under same vacuum condition and constant inter-electrode separation. Field emission of solid square dot CEAs show approximately identical current density-electric field curves and Fowler-Nordheim plots with little difference in emission current density at same electric field. Similar results were observed for ring square structure CEAs when compared separately. Maximum emission current density observed from these four CEAs reduces from 14.53, 12.23, 11.01, to 8.66 mA/cm2 at a constant electric field of 5 V/μm, according to edge length of 1361.7, 1221.08, 872.20, to 872.16 mm rather than growth area and purity. Although, the 40 μm × 40 μm CEAs possessed highest CNT growth area of 8.7 mm2 and best purity defined in terms of lowest defect band to graphitic band ratio of 0.614, the current observed from this CEAs was least.
Interface trap characterization of atomic layer deposition Al2O3/GaN metal-insulator-semiconductor capacitors using optically and thermally based deep level spectroscopies
Authors: Jackson Christine M. , Arehart Aaron R. , Cinkilic Emre , McSkimming Brian , Speck James S. , Ringel Steven A.
Published: June 2013

Quantitative measurements of interface state density and energy distribution profiles within Al2O3/GaN interfaces were obtained by constant capacitance deep level transient spectroscopy and deep level optical spectroscopy (CC-DLTS/DLOS). The new application of CC-DLOS to interface state measurement is described, which allows interrogation of very deep interface states. A series of Al2O3/GaN metal-insulator-semiconductor (MIS) devices prepared as a function of Al2O3 thickness via atomic layer deposition, on NH3-MBE-grown n-type Ga-polar GaN layers enabled a systematic study. The overall shape and magnitude of the interface trap distribution, Dit, were determined to be nearly identical, independent of Al2O3 thickness. The Al2O3/GaN Dit spectra had an overall U-shape with Dit ∼1012 cm−2 eV−1 near the conduction band edge, ∼1011 cm−2 eV−1 mid-gap, and ∼1014 cm−2 eV−1 near the valence band edge. However, the interface states near the GaN conduction band showed a slight inverse dependence on Al2O3 thickness, suggestive of annealing effect during deposition. The high near valence band state concentrations are consistent with expectations from residual carbon impurities at the GaN surface. A method for discriminating between bulk and interface states in the CC-DLTS signal is demonstrated, using the results on MIS capacitors in combination with spectroscopy results on a Schottky diode structure.
Structural ordering driven anisotropic magnetoresistance, anomalous Hall resistance, and its topological overtones in full-Heusler Co2MnSi thin films
Authors: Pandey Himanshu , Budhani R. C.
Published: June 2013

We report the evolution of crystallographic structure, magnetic ordering, and electronic transport in thin films of full-Heusler alloy Co2MnSi deposited on (001) MgO with annealing temperatures (TA). By increasing the TA from 300 °C to 600 °C, the film goes from a disordered nanocrystalline phase to B2 ordered and finally to the L21 ordered alloy. The saturation magnetic moment improves with structural ordering and approaches the Slater-Pauling value of ≈5.0μB per formula unit for TA=600 °C. At this stage, the films are soft magnets with coercive and saturation fields as low as ≈7 mT and 350 mT, respectively. Remarkable effects of improved structural order are also seen in longitudinal resistivity (ρxx) and residual resistivity ratio. A model based upon electronic transparency of grain boundaries illucidates the transition from a state of negative dρ/dT to positive dρ/dT with improved structural order. The Hall resistivity (ρxy) derives contribution from the normal scattering of charge carriers in external magnetic field, the anomalous effect originating from built-in magnetization, and a small but distinct topological Hall effect in the disordered phase. The carrier concentration (n) and mobility (μ) have been extracted from the high field ρxy data. The highly ordered films are characterized by n and μ of 1.19 × 1029 m−3 and 0.4 cm2V−1s−1 at room temperature. The dependence of ρxy on ρxx indicates the dominance of skew scattering in our films, which shows a monotonic drop on raising the TA. The topological Hall effect is analyzed for the films annealed at 300 °C. We find maximum topological contribution to Hall resistivity around 0.5 T while it approach to zero with increasing magnetic field. The anisotropic magnetoresistance changes its sign from positive to negative as we go from as deposited to 600 °C annealed film, suggesting a gradual increase in the half-metallic character.
Near-perfect infrared absorption from dielectric multilayer of plasmonic aluminum-doped zinc oxide
Authors: Zhang Yun , Wei Tiaoxing , Dong Wenjing , Huang Chanyan , Zhang Kenan , Sun Yan , Chen Xin , Dai Ning
Published: June 2013

We demonstrated a near-perfect infrared absorber by using nanostructure multilayer of aluminum doped zinc oxide (AZO) and ZnO. The negative real part of permittivity of AZO allows the dielectric multilayer to match the phase of all light reflected. The field amplitudes destructive interference leads to a reflectance closing to zero at ∼1.90 μm. Both experimental and theoretical investigations indicated that the multilayer simultaneously minimized reflectance and transmittance in infrared region, leading to a high absorptance of ∼99% at ∼1.90 μm. These AZO metamaterials will bring more opportunities for simplified fabrications and something new towards plasmonics and artificial optics.
High speed atomic force microscopy enabled by a sample profile estimator
Authors: Huang Peng , Andersson Sean B.
Published: June 2013

In this paper, an estimation scheme for imaging in Atomic Force Microscopy (AFM) is presented which yields imaging rates well beyond the bandwidth of the vertical positioner and allows for high-speed AFM on a typical commercial instrument. The estimator can be applied to existing instruments with little to no hardware modification other than that needed to sample the cantilever signal. Experiments on a calibration sample as well as lambda DNA are performed to illustrate the effectiveness of this method. These show a greater than an order-of-magnitude improvement in the imaging rate.
Charge-induced reversible bending in nanoporous alumina-aluminum composite
Authors: Cheng Chuan , Ngan A. H. W.
Published: June 2013

Upon electrical charging, reversible bending was found in nanoporous anodic alumina-aluminum foil composites, as directly observed by an optical microscope and detected by in situ nanoindentation. The bending is thought to be the result of charge-induced surface stresses in the nanoporous alumina. The results suggest the possibility of a type of composite foil materials for applications as micro-scale actuators to transform electrical energy into mechanical energy.
Evolutionary optimization of an experimental apparatus
Authors: Geisel I. , Cordes K. , Mahnke J. , Jöllenbeck S. , Ostermann J. , Arlt J. , Ertmer W. , Klempt C.
Published: June 2013

In recent decades, cold atom experiments have become increasingly complex. While computers control most parameters, optimization is mostly done manually. This is a time-consuming task for a high-dimensional parameter space with unknown correlations. Here we automate this process using a genetic algorithm based on differential evolution. We demonstrate that this algorithm optimizes 21 correlated parameters and that it is robust against local maxima and experimental noise. The algorithm is flexible and easy to implement. Thus, the presented scheme can be applied to a wide range of experimental optimization tasks.
Carrier transport processes in dye sensitized solar cells based on Zn2SnO4 nanostructures studied by intensity modulated photocurrent/photovoltage spectroscopy
Authors: Chen Jiajun , Wang Wenyong
Published: June 2013

In this work, the electron transport and recombination processes in dye sensitized solar cells (DSSCs) based on Zn2SnO4 nanowires and nanoparticles were studied by intensity modulated photocurrent spectroscopy (IMPS)/photovoltage spectroscopy. Two distinct transport time constants were obtained from the IMPS spectra of Zn2SnO4 nanowire-DSSCs, which were associated with a fast, direct transport through the single crystalline structure of the nanowires and a slow, percolation transport that was assisted by the nanowire surface states, respectively. The charge collection efficiency for the fast transport process was close to unity in all the measurements at different light intensities, indicating that the overall charge collection efficiency of nanowire-DSSCs could be enhanced if the slow transport process could be suppressed.
Study on the impact of the initialization process on the phase change memory
Authors: Ren Kun , Rao Feng , Song Zhitang , Lv Shilong , Zhu Min , Wu Liangcai , Liu Bo , Feng Songlin
Published: June 2013

The set processes of T-shape phase change memory (PCRAM) cell are compared to study the change caused by the initialization. After the initialization, PCRAM cell shows lower Vth and minor resistances than those of the 1st operation, which can be explained by the reduction of contact resistance caused by the formation of the crystalline phase change material interface (CPI) near the electrodes. The temperature transition regions between the programmed region and the electrodes preserve the CPI after its formation in the initial operation. Thus, we suggest the formation of CPI is the key role for the initialization.
Hexagonal boron nitride and 6H-SiC heterostructures
Authors: Majety S. , Li J. , Zhao W. P. , Huang B. , Wei S. H. , Lin J. Y. , Jiang H. X.
Published: June 2013

Hexagonal boron nitride (hBN) epilayers were grown on n-type 6H-SiC substrates via metal organic chemical vapor deposition. X-ray diffraction measurements confirmed that the epilayers are of single hexagonal phase. Photoluminescence (PL) studies revealed a dominant band edge emission at around 5.5 eV, similar to the PL spectra of hBN epilayers grown on sapphire. The current-voltage (I-V) characteristics of the hBN/6H-SiC heterostructure were measured and the results were utilized to determine the band offsets of the hBN/6H-SiC heterojunctions. The analysis yielded the conduction and valence band offsets (ΔEC and ΔEV) of the hBN/6H-SiC heterointerface of about 2.3 and 0.7 (±0.2) eV, respectively, giving a ΔEC/ΔEg value of around 76%. The measured band offsets are in reasonable agreement with values deduced from the band alignments between hBN, AlN, and 6H-SiC obtained from independent experimental data and theoretical calculations.
Enhancement of p-type mobility in tin monoxide by native defects
Authors: Granato D. B. , Caraveo-Frescas J. A. , Alshareef H. N. , Schwingenschlögl U.
Published: June 2013

Transparent p-type materials with good mobility are needed to build completely transparent p-n junctions. Tin monoxide (SnO) is a promising candidate. A recent study indicates great enhancement of the hole mobility of SnO grown in Sn-rich environment [E. Fortunato et al., Appl. Phys. Lett. 97, 052105 (2010)]. Because such an environment makes the formation of defects very likely, we study defect effects on the electronic structure to explain the increased mobility. We find that Sn interstitials and O vacancies modify the valence band, inducing higher contributions of the delocalized Sn 5p orbitals as compared to the localized O 2p orbitals, thus increasing the mobility. This mechanism of valence band modification paves the way to a systematic improvement of transparent p-type semiconductors.
Carrier dynamics in InP nanopillar arrays fabricated by low-damage etching
Authors: Naureen S. , Shahid N. , Gustafsson A. , Liuolia V. , Marcinkevičius S. , Anand S.
Published: June 2013

We present a comprehensive characterization of the optical quality of InP nanopillars (NPs) fabricated by a top down approach using micro-photoluminescence (μ-PL), time-resolved PL, and cathodoluminescence (CL). A lattice matched InGaAs layer provided beneath the 1 μm tall NPs functions as a “detector” in CL for monitoring carrier diffusion in InP NP. Carrier feeding to the InGaAs layer indicated by a double exponential PL decay is confirmed through CL mapping. Carrier lifetimes of over 1 ns and the appreciably long diffusion lengths (400–700 nm) in the InP NPs indicate very low surface damage making them attractive for optoelectronic applications.
On the effect of the underlying ZnO:Al layer on the crystallization kinetics of hydrogenated amorphous silicon
Authors: Sharma K. , Ponomarev M. V. , van de Sanden M. C. M. , Creatore M.
Published: June 2013

In this contribution, we analyze the thickness effect of the underlying aluminum doped-zinc oxide (ZnO:Al) layers on the structural properties and crystallization kinetics of hydrogenated amorphous silicon (a-Si:H) thin films. It is shown that the disorder in as-deposited a-Si:H films, as probed by Raman spectroscopy, decreased with increasing ZnO:Al roughness. This caused an earlier nucleation upon crystallization when compared to a-Si:H layers directly grown on SiNx-coated glass.
Semiconductor layer thickness impact on optical and resistive switching behavior of pulsed laser deposited BaTiO3/ZnO heterostructures
Authors: Sekhar K. C. , Silva J. P. B. , Kamakshi Koppole , Pereira M. , Gomes M. J. M.
Published: June 2013

This work reports the impact of ZnO layer thickness on optical and resistive switching behavior of BaTiO3/ZnO heterostructures grown by pulsed laser deposition. The interface polarization coupling becomes more efficient and causes a remarkable change in heterostructure properties with decrease in ZnO layer thickness. The heterostructure with ZnO thickness of 25 nm displays the enhanced resistive switching characteristics with switching ratio ≈106 and good stability in low and high resistance states. Moreover, the photoluminescence spectrum exhibits two additional blue emissions when ZnO thickness is ≤50 nm and their mechanism is highlighted based on interface band offset and interface polarization coupling effect.
Circuit-based nonlinear metasurface absorbers for high power surface currents
Authors: Wakatsuchi Hiroki , Kim Sanghoon , Rushton Jeremiah J. , Sievenpiper Daniel F.
Published: June 2013

We demonstrate a concept of circuit-based nonlinear metasurface absorbers that absorb high power surface currents but not small signals. The nonlinear absorbing behavior is achieved through the use of diodes integrated into the metasurface. The diodes rectify high power signals to produce a static field, whose energy is stored in capacitors and then dissipated with resistors. We present electromagnetic simulations of these structures and validate the results with the first measurements of nonlinear metasurface absorbers. The metasurfaces can potentially contribute to solving a wide range of microwave interference issues due to their power dependent electromagnetic response.
Two-photon pumped lasing in a single CdS microwire
Authors: Zhang Lichao , Wang Kai , Liu Zhe , Yang Guang , Shen Guozhen , Lu Peixiang
Published: June 2013

We report the two-photon absorption induced lasing performance in a single CdS microwire under the excitation of a femtosecond pulse laser with a wavelength of 800 nm. Sharp lasing peaks are centered at 523 nm with an average linewidth of 0.4 nm, indicating a high quality factor of 1300. The lasing emission is highly dependent on the polarization direction of the excitation light and the optimized lasing threshold is estimated to be 3.3 mJ/cm2 as the polarization direction is parallel to the microwire axis. Furthermore, the polarization-dependent lasing effect is confirmed by performing the finite-difference time-domain method.
Water in the atmosphere
Authors: Stevens Bjorn , Bony Sandrine
Published: June 2013

Much of what we know, and even more of what we don’t know, about Earth’s climate and its propensity to change is rooted in the interplay between water, air circulation, and temperature.
The evolution of hadron-collider experiments
Authors: Grannis Paul , Jenni Peter
Published: June 2013

High-energy accelerator beams colliding head-on have now completed the discovery of all the fundamental particles required by particle theory’s standard model. The search is on for new ones.
Programmable matter
Authors: Knaian Ara N.
Published: June 2013

A new kind of electric motor is the cornerstone of a chain that can bend itself into multiple shapes.
Glutamate is an inhibitory neurotransmitter in the
Drosophila
olfactory system
Authors: Liu Wendy W. , Wilson Rachel I.
Published: June 2013

Glutamatergic neurons are abundant in the
Drosophila
central nervous system, but their physiological effects are largely unknown. In this study, we investigated the effects of glutamate in the
Drosophila
antennal lobe, the first relay in the olfactory system and a model circuit for understanding olfactory processing. In the antennal lobe, one-third of local neurons are glutamatergic. Using in vivo whole-cell patch clamp recordings, we found that many glutamatergic local neurons are broadly tuned to odors. Iontophoresed glutamate hyperpolarizes all major cell types in the antennal lobe, and this effect is blocked by picrotoxin or by transgenic RNAi-mediated knockdown of the
GluC
l
α gene, which encodes a glutamate-gated chloride channel. Moreover, antennal lobe neurons are inhibited by selective activation of glutamatergic local neurons using a nonnative genetically encoded cation channel. Finally, transgenic knockdown of
GluCl
α in principal neurons disinhibits the odor responses of these neurons. Thus, glutamate acts as an inhibitory neurotransmitter in the antennal lobe, broadly similar to the role of GABA in this circuit. However, because glutamate release is concentrated between glomeruli, whereas GABA release is concentrated within glomeruli, these neurotransmitters may act on different spatial and temporal scales. Thus, the existence of two parallel inhibitory transmitter systems may increase the range and flexibility of synaptic inhibition.
Suspended microfluidics
Authors: Casavant Benjamin P. , Berthier Erwin , Theberge Ashleigh B. , Berthier Jean , Montanez-Sauri Sara I. , Bischel Lauren L. , Brakke Kenneth , Hedman Curtis J. , Bushman Wade , Keller Nancy P. , Beebe David J.
Published: June 2013

Although the field of microfluidics has made significant progress in bringing new tools to address biological questions, the accessibility and adoption of microfluidics within the life sciences are still limited. Open microfluidic systems have the potential to lower the barriers to adoption, but the absence of robust design rules has hindered their use. Here, we present an open microfluidic platform, suspended microfluidics, that uses surface tension to fill and maintain a fluid in microscale structures devoid of a ceiling and floor. We developed a simple and ubiquitous model predicting fluid flow in suspended microfluidic systems and show that it encompasses many known capillary phenomena. Suspended microfluidics was used to create arrays of collagen membranes, mico Dots (μDots), in a horizontal plane separating two fluidic chambers, demonstrating a transwell platform able to discern collective or individual cellular invasion. Further, we demonstrated that μDots can also be used as a simple multiplexed 3D cellular growth platform. Using the μDot array, we probed the combined effects of soluble factors and matrix components, finding that laminin mitigates the growth suppression properties of the matrix metalloproteinase inhibitor GM6001. Based on the same fluidic principles, we created a suspended microfluidic metabolite extraction platform using a multilayer biphasic system that leverages the accessibility of open microchannels to retrieve steroids and other metabolites readily from cell culture. Suspended microfluidics brings the high degree of fluidic control and unique functionality of closed microfluidics into the highly accessible and robust platform of open microfluidics.
Multiple risk pathways for schizophrenia converge in serine racemase knockout mice, a mouse model of NMDA receptor hypofunction
Authors: Balu Darrick T. , Li Yan , Puhl Matthew D. , Benneyworth Michael A. , Basu Alo C. , Takagi Shunsuke , Bolshakov Vadim Y. , Coyle Joseph T.
Published: June 2013

Significance

We sought to determine whether the diverse hippocampal neuropathology observed in schizophrenia could be recapitulated in an animal model of NMDA receptor (NMDAR) hypofunction. Serine racemase-deficient (SR−/−) mice, which lack one of the NMDAR coagonistsd-serine, display impaired hippocampal plasticity, as well as the morphological, neurochemical, and cognitive abnormalities consistent with what is observed in schizophrenia. Importantly, treatment in adulthood withd-serine reversed the electrophysiological, neurochemical, and cognitive deficits. These results demonstrate that NMDAR hypofunction can reproduce the hippocampal deficits associated with schizophrenia and point to potential interventions for the currently untreatable negative and cognitive symptoms of this disorder.
Resident Characterization of Better-than- and Worse-than-Average Clinical Teaching
Authors: Haydar Bishr , Charnin Jonathan , Voepel-Lewis Terri , Baker Keith
Published: June 2013

Background:

Clinical teachers and trainees share a common view of what constitutes excellent clinical teaching, but associations between these behaviors and high teaching scores have not been established. This study used residents’ written feedback to their clinical teachers, to identify themes associated with above- or below-average teaching scores.

Methods:

All resident evaluations of their clinical supervisors in a single department were collected from January 1, 2007 until December 31, 2008. A mean teaching score assigned by each resident was calculated. Evaluations that were 20% higher or 15% lower than the resident’s mean score were used. A subset of these evaluations was reviewed, generating a list of 28 themes for further study. Two researchers then, independently coded the presence or absence of these themes in each evaluation. Interrater reliability of the themes and logistic regression were used to evaluate the predictive associations of the themes with above- or below-average evaluations.

Results:

Five hundred twenty-seven above-average and 285 below-average evaluations were evaluated for the presence or absence of 15 positive themes and 13 negative themes, which were divided into four categories: teaching, supervision, interpersonal, and feedback. Thirteen of 15 positive themes correlated with above-average evaluations and nine had high interrater reliability (Intraclass Correlation Coefficient >0.6). Twelve of 13 negative themes correlated with below-average evaluations, and all had high interrater reliability. On the basis of these findings, the authors developed 13 recommendations for clinical educators.

Conclusions:

The authors developed 13 recommendations for clinical teachers using the themes identified from the above- and below-average clinical teaching evaluations submitted by anesthesia residents.