bluuebunny/crossref_metadata_2025 huggingface dataset:
Immobilization of BMP-2 on a Nano-Hydroxyapatite-Coated Titanium Surface using a Chitosan Calcium Chelating Agent
Authors: Kim Sung-Hyun , Park Jung-Keug , Hong Kug-Sun , Jung Hyun-Suk , Seo Young-Kwon
Published: May 2013

We conducted experiments to determine the most effective calcium chelating agents for use in enhancing adhesion of human bone marrow mesenchymal stem cells (BM-MSCs) on nano-hydroxyapatite (nHAp)-coated titanium substrates by covalently immobilizing bone morphogenetic protein-2 (BMP-2). The quantity of amine groups on the chitosan chelated surface was 7 μg/surface area, and it was 1.4 μg/surface area on the alendronate chelated surface. The quantity of BMP-2 on the BMP-2 immobilized surface chelated with chitosan (4 ng/surface area) was higher than that on BMP-2 immobilized surface chelated with alendronate (2.2 ng/surface area). Contact angles of the nHAp-coated titanium, alendronate chelated, chitosan chelated, and BMP-2 immobilized surfaces chelated with alendronate were 68.8 ± 3.6°, 78.2 ± 1.9°, 74.8 ± 5.2°, and 76.0 ± 2.5°, respectively. The contact angle of the BMP-2 immobilized surface chelated with chitosan was significantly lower (56.2 ± 2.0°) than that of any of the other groups. BM-MSCs on the chitosan surface and BMP-2 immobilized on the surface chelated with chitosan appeared to be healthy and showed a spindle-like fibroblastic morphology. In addition, BM-MSCs on these surfaces appeared to have the ability to differentiate into bone-forming cells. We suggest that chitosan can be used as an effective calcium chelating agent for implants.
Maslow and the Motivation Hierarchy: Measuring Satisfaction of the Needs
Authors: Taormina Robert J. , Gao Jennifer H.
Published: May 2013

For each of the 5 needs in Maslow’s motivational hierarchy (physiological, safety-security, belongingness, esteem, and self-actualization), operational definitions were developed from Maslow’s theory of motivation. New measures were created based on the operational definitions (1) to assess the satisfaction of each need, (2) to assess their expected correlations (a) with each of the other needs and (b) with four social and personality measures (i.e., family support, traditional values, anxiety/worry, and life satisfaction), and (3) to test the ability of the satisfaction level of each need to statistically predict the satisfaction level of the next higher-level need. Psychometric tests of the scales conducted on questionnaire results from 386 adult respondents from the general population lent strong support for the validity and reliability of all 5 needs measures. Significant positive correlations among the scales were also found; that is, the more each lower-level need was satisfied, the more the next higher-level need was satisfied. Additionally, as predicted, family support, traditional values, and life satisfaction had significant positive correlations with the satisfaction of all 5 needs, and the anxiety/worry facet of neuroticism had significant negative correlations with the satisfaction of all the needs. Multiple regression analyses revealed that the satisfaction of each higher-level need was statistically predicted by the satisfaction of the need immediately below it in the hierarchy, as expected from Maslow’s theory.
Characterizing the Developmental Profile of Effort-Induced Motor Overflow Across a Timed Trial
Authors: Addamo Patricia K. , Farrow Maree , Bradshaw John L. , Moss Simon , Georgiou-Karistianis Nellie
Published: May 2013

Motor overflow is overt involuntary movement that accompanies voluntary movement. This study investigated the change in overflow production across a timed trial and the factors that affected this profile. Seventeen children (aged 8-11 years), 17 young adults (aged 18-35 years), and 17 older adults (aged 60-80 years) performed a 5-s finger pressing task by exerting 33% or 66% of their maximal force output using either index finger. Overflow was recorded as force from the alternative index finger. Young adult overflow remained stable over the 5 s. The rate of overflow increase over time was significantly greater for children than young adults. There was also a tendency for a greater overflow increase in older adults than in young adults. This overflow gradient was also greater in the right hand, particularly for children. These findings indicate that the neurological processes underlying overflow production are age dependent. Overflow progressed in a dynamic fashion over the course of a trial in children and older adults, probably because of increased bilateral cortical activation and the facilitation of motor task performance. This study is unique in quantitatively capturing the dynamic profile of overflow production in healthy participants across the life span.
Robust Control of Collaborative Manipulators - Flexible Object System
Authors: Esakki Balasubramanian , Bhat Rama B. , Su Chun-Yi
Published: May 2013

Abstract In many manufacturing and automobile industries, flexible components need to be positioned with the help of coordinated operations of manipulators. This paper deals with the robust design of a control system for two planar rigid manipulators moving a flexible object in the prescribed trajectory while suppressing the vibration of the flexible object. Dynamic equations of the flexible object are derived using the Hamiltonian principle, which is expressed as a partial differential equation (PDE) with appropriate boundary conditions. Then, a combined dynamics is formulated by combining the manipulators and object dynamics without any approximation. The resulting dynamics are thus described by the PDEs, having rigid as well as flexible parameters coupled together. This paper attempts to develop a robust control scheme without approximating the PDE in order to avoid measurements of flexible coordinates and their time derivatives. For this purpose, the two subsystems, namely slow and fast subsystems, are identified by using the singular perturbation technique. Specific robust controllers for both the subsystems are developed. In general, usage of the singular perturbation technique necessitates exponential stability of both subsystems, which is evaluated by satisfying Tikhnov's theorem. Hence, the exponential stability analysis is performed for both subsystems. Focusing on two three-link manipulators holding a flexible beam, simulations are performed and simulation results demonstrate the versatility of the proposed robust composite control scheme.
Adaptive RBF Neural Network Control for Three-Phase Active Power Filter
Authors: Fei Juntao , Wang Zhe
Published: May 2013

Abstract An adaptive radial basis function (RBF) neural network control system for three-phase active power filter (APF) is proposed to eliminate harmonics. Compensation current is generated to track command current so as to eliminate the harmonic current of non-linear load and improve the quality of the power system. The asymptotical stability of the APF system can be guaranteed with the proposed adaptive neural network strategy. The parameters of the neural network can be adaptively updated to achieve the desired tracking task. The simulation results demonstrate good performance, for example showing small current tracking error, reduced total harmonic distortion (THD), improved accuracy and strong robustness in the presence of parameters variation and nonlinear load. It is shown that the adaptive RBF neural network control system for three-phase APF gives better control than hysteresis control.
Resemblance of Dinner Meal Consumption among Mother and Preschool-Aged Child Dyads from Families with Limited Incomes
Authors: Nicklas Theresa A. , O’Neil Carol E. , Hughes Sheryl O. , Liu Yan
Published: May 2013

Parents’ eating habits are associated with food and nutrient intake of their children; yet, the associations have not always been very strong. The objective of this study was to expand the current literature to include an examination of resemblance in intakes of foods, within the context of a meal, among mother and preschool-aged child dyads from families of limited incomes. Mother-child dyads (n=112; 41% Hispanic and 59% African-American) participated in the study. During the two home observations of each mother-child dyad, a digital photography method plus actual weighing of plate waste was used to assess the amount of food served and consumed by the mothers and children. There were significant correlations between the mother-child dyad intakes of food/beverages consumed at the dinner meal; ranging from 0.298 (total beverages, p<0.01) to 0.687 (100% fruit juice or milk, p<0.01). There was a significant linear association between the amount of total food/beverages served and the amount consumed for both the mothers (R2=0.72, p<0.0001) and the children (R2=0.55, p<0.0001). Mothers-children who were served larger amounts of total food/beverages consumed more. There was a positive association (p<0.05) between the amount of total energy consumed in the mother-child dyads. Portion sizes may be an important strategy that can be used by parents to promote intake of fruits and vegetables and to decrease intake of energy-dense foods. It is important that food and nutrition professionals provide the guidance needed that encourages intake of major food groups in mothers so they can model healthier food consumption behaviors for their children.
Design, Characterization and Evaluation of Metallic Nano Biocomposites of Neomycin
Authors: Swathi Vottikuti , Vidyavathi Maravajhala , Prasad T.N.V.K.V. , Kumar R.V. Suresh
Published: May 2013

Neomycin is formulated into nanoparticles in order to increase the therapeutic efficacy, decrease the dose of drug and to decrease the topical dose related toxic effects. The present study was aimed at the preparation of zinc nanoparticles (ZN), chitosan nanoparticles (CN), zinc neomycin nanoparticles (ZNN) and zinc chitosan neomycin nanoparticles (ZCNN) in order to compare their antibacterial activity. Nanoparticles were prepared by subjecting the nano suspension containing the specified ingredients to stirring at 40oC for 4-5 h. The prepared nanoparticles were evaluated for particle size and surface morphology by Transmission Electron Microscopy (TEM), mean particle size and particle size distribution by DLS, percentage yield, loading efficiency, in vitro drug release by diffusion technique and agar cup plate method. TEM microphotographs and zeta sizer analysis revealed that the prepared nanoparticles were in the nanometric range, the particle size and particle size range of ZCNN was less compared to ZNN indicated more surface area of ZCNN. Among all the nanoparticles prepared, percentage yield, loading efficiency, in vitro drug release and zone of inhibition was found to be more for ZCNN. Thus, the results suggested that ZCNN act as promising drug delivery systems with better in vitro characteristics compared to other nanoparticles with increased therapeutic activity of neomycin.
High-Performance Amorphous Indium Oxide Thin-Film Transistors Fabricated by an Aqueous Solution Process at Low Temperature
Authors: Choi Kookhyun , Kim Minseok , Chang Seongpil , Oh Tae-Yeon , Jeong Shin Woo , Ha Hyeon Jun , Ju Byeong-Kwon
Published: May 2013

This paper presents low temperature solution-processed fabrication techniques for modern thin-film transistors (TFTs). We have investigated the electrical performance of aqueous solution-processed amorphous indium oxide (a-In2O3) TFTs prepared using different annealing temperatures. Even though the a-In2O3TFTs were annealed at 200 °C, electrical characteristics of aqueous solution-processed a-In2O3TFTs were obtained. High performance such as a saturation mobility of 8.6 cm2V-1s-1and an on/off current ratio of over 106was exhibited by a-In2O3TFTs annealed at 250 °C.
First-Principles Studies on Cd Doping in CuInSe2 and Related Compounds during Chemical Bath Deposition of CdS Buffer Layer
Authors: Maeda Tsuyoshi , Wada Takahiro
Published: May 2013

First-principles calculations using plane-wave basis functions were performed to quantitatively evaluate the substitution energies of Cd atom for Cu atom and for In atoms in chalcopyrite-type CuInSe2 (CIS) and related compounds, CuGaSe2 (CGS) and CuAlSe2 (CAS). The substitution energies of Cd atoms in CIS and the related compounds were calculated in considering of the atomic chemical potentials of the constituent elements of Cu and In, and doping Cd atoms. During the chemical bath deposition (CBD) of the CdS layer on the CIGS layer, Cu and Cd atoms dissolved in the ammonia aqueous solution and formed [Cu(NH3)2]+ and [Cd(NH3)4]2+ complex ions. Therefore, the chemical potentials of Cu and Cd atoms in [Cu(NH3)2]+ and [Cd(NH3)4]2+ complex ions were calculated. We found that the substitution energy of n-type CdCu is smaller than that of p-type CdIn. The substitution energy of CdCu in CIS is smaller than those in CGS and CAS. However, the substitution energies of CdCu and CdIn in CIS are positive values. The formation energy of charge-neutral Cd doping with the Cu vacancy (CdCu+VCu) pair is a negative value and greatly smaller than those of n-type CdCu in CIS, CGS, and CAS. These results indicate that the charge-neutral (CdCu+VCu) vacancy pair is easily formed during the CBD of the CdS layer on the CIS layer and a small amount of n-type CdCu would also be formed.
Tunneling Current Spectra of a Metal Core/Semiconductor Shell Quantum Dot Molecule
Authors: Kuo David M.-T.
Published: May 2013

The transport properties of a metal core/semiconductor shell quantum dot molecule (QDM) embedded in a matrix connected to metallic electrodes are theoretically studied in the framework of Keldysh Green function technique. The effects of the electron plasmon interactions (EPIs) on the tunneling current spectra of QDM are examined. The energy levels of the QDs, intradot and interdot Coulomb interactions, electron interdot hopping strengths, and tunneling rates of QDs are renormalized by the EPIs. The differential conductance spectra show peaks arising from the plasmon assisted tunneling process, intradot and interdot Coulomb interactions, and coherent tunneling between the QDs.
Self-Separation of Large Freestanding Semipolar {112̄2} GaN Films Using r-Plane Patterned Sapphire Substrates
Authors: Furuya Hiroshi , Yamane Keisuke , Okada Narihito , Tadatomo Kazuyuki
Published: May 2013

We have studied the growth of semipolar GaN from the etched sapphire sidewall of a patterned sapphire substrate (PSS). In this work, we grew a thick {112̄2} GaN layer on an r-plane PSS (r-PSS) by hydride vapor phase epitaxy (HVPE) and separated the GaN layer from the r-PSS. We demonstrated the self-separation of the {112̄2} GaN layer from the r-PSS by using a PSS and thick GaN growth. The ease of separation of the GaN layer from the PSS depended on the selective growth area of the sapphire sidewall. Consequently, we obtained a freestanding {112̄2} GaN film of 2-in. diameter. The dark spot density of this film was 2.8×107/cm2.
Growth of GaN on Si(111) Substrates via a Reactive-Sputter-Deposited AlN Intermediate Layer
Authors: Yamada Takaya , Tanikawa Tomoyuki , Honda Yoshio , Yamaguchi Masahito , Amano Hiroshi
Published: May 2013

GaN films were successfully grown on Si(111) substrates using a reactive-sputter-deposited AlN intermediate layer (sp-AlN) at 350 °C. Uniform GaN growth was obtained with the pre sputtering of a thin Al film before the deposition of sp-AlN. Atomic force microscopy (AFM) measurements revealed that the density of pits originating from the ends of mixed/screw-type dislocations is about 109 cm-2, which is much lower than that of GaN grown on a metalorganic vapor phase epitaxy (MOVPE) deposited AlN intermediate layer. The decrease in the pit density might have originated from the small number of initial nuclei of GaN.
A Comparative Study on Metalorganic Vapor Phase Epitaxial InGaN with Intermediate In Compositions Grown on GaN/Sapphire Template and AlN/Si(111) Substrate
Authors: Yamamoto Akio , Mihara Akihiro , Zheng Yangdong , Shigekawa Naoteru
Published: May 2013

The growth of InGaN with intermediate In compositions on GaN/sapphire template and AlN/Si(111) substrate has been comparatively studied. By using an metalorganic vapor phase epitaxy (MOVPE) system with a horizontal reactor, InGaN films are grown at a temperature of 600–800 °C in the pressure of 150 Torr. By optimizing growth temperature and trimethylindium/(trimethylindium+ triethylgallium) molar ratio, single crystalline In
x
Ga1-x
N with x = 0–1 are successfully grown on both substrates. The films grown at a relatively high temperature (≥700 °C) with In compositions of 0.3 or less show phase separation when their thickness exceeds a critical value (0.25–0.4 µm), while the samples grown at 600 °C with In compositions of 0.35–0.5 show no phase separation even if the thickness is increased to 0.7 µm. To evaluate the crystalline quality of grown films, FWHM of X-ray rocking curve (XRC) for InGaN(0002), tilt, is measured. There is no marked difference in tilt data between films grown on GaN/α-Al2O3(0001) and AlN/Si(111). For the samples grown at 600 °C with In contents of 0.35–0.5, tilt data are drastically increased and widely scattered suggesting the existence of important unknown parameters that govern crystalline quality of InGaN grown at a relatively low temperature.
Effect of Growth Temperature on Formation of Amorphous Nitride Interlayer between AlN and Si(111)
Authors: Lin Pei-Yin , Chen Jr-Yu , Chen Yu-Chang , Chang Li
Published: May 2013

The formation of an amorphous interlayer between AlN and Si(111), which may degrade the film quality, is studied by varying the substrate temperature from 860 to 1010 °C in metal–organic chemical vapor deposition with a preflow of trimethylaluminum. The microstructure and chemistry of the amorphous interlayer have been investigated using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Cross-sectional TEM examinations show that AlN is directly in contact with Si for growth at 860 °C. At higher growth temperatures, an amorphous interlayer can be formed even if an AlN layer has been previously deposited on Si, and its thickness increases with growth temperature. The XPS depth profile across the amorphous interlayer formed at 1010 °C shows that both Al and N exhibit similar distribution, which gradually decreases toward the Si substrate whereas the Si concentration has the opposite distribution. The composition of the amorphous interlayer is determined to consist of Al, Si, and N.
Indium Nitride Film Growth by Metal Organic Chemical Vapor Deposition with Nitrogen Activation in Electron Cyclotron Resonance Discharge Sustained by 24 GHz Gyrotron Radiation
Authors: Vodopyanov Alexander , Mansfeld Dmitry , Buzynin Yurii , Drozdov Mikhail , Drozdov Yurii , Khrykin Oleg , Lukyanov Andrei , Viktorov Mikhail , Golubev Sergey , Shashkin Vladimir
Published: May 2013

We report the results of the first experiments on the growth of indium nitride films by electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition. Discharge sustained by the radiation of a technological gyrotron with a frequency of 24 GHz and power up to 5 kW was used to provide active nitrogen flow. The use of higher frequency microwave radiation for plasma heating provides a higher plasma density, and more active nitrogen flow. Mirror-smooth homogeneous hexagonal InN films were grown on ittria-stabilized zirconia and sapphire substrates. It was shown that single-crystal InN films can be grown on Al2O3 (0001) substrates if a double buffer layer of InN/GaN is used. The growth rate of 1 µm/h was demonstrated in this case. Film properties are studied by optical and electron microscopies, secondary ion mass spectroscopy, X-ray diffraction, and photoluminescence.
Nature of V-Shaped Defects in GaN
Authors: Voronenkov Vladislav , Bochkareva Natalia , Gorbunov Ruslan , Latyshev Philipp , Lelikov Yuri , Rebane Yury , Tsyuk Alexander , Zubrilov Andrey , Shreter Yuri
Published: May 2013

GaN films with thicknesses up to 3 mm were grown in two custom-made halide vapor phase epitaxy (HVPE) reactors. V-shaped defects (pits) with densities from 1 to 100 cm-2 were found on the surfaces of the films. Origins of pit formation and the process of pit overgrowth were studied by analysing the kinematics of pit evolution. Two mechanisms of pit overgrowth were observed. Pits can be overgrown intentionally by varying growth parameters to increase the growth rate of pit facets. Pits can overgrow spontaneously if a fast-growing facet nucleates at their bottom under constant growth conditions.
Control of the Detection Wavelength in AlGaN/GaN-Based Hetero-Field-Effect-Transistor Photosensors
Authors: Ishiguro Mami , Ikeda Kazuya , Mizuno Masataka , Iwaya Motoaki , Takeuchi Tetsuya , Kamiyama Satoshi , Akasaki Isamu
Published: May 2013

We examined the control of the detection wavelength in AlGaN/GaN-based hetero-field-effect-transistor (HFET) photosensors. The detection wavelength of these devices can be controlled by using the p-GaInN optical gate or inserting a GaInN channel layer between AlGaN and GaN. In addition, the photosensitivity of AlGaN/GaN HFET photosensors with a p-GaInN optical gate was more than two orders of magnitude higher than that of the AlGaN/GaN HFET photosensor with a GaInN channel layer. Moreover, the photosensitivity of the AlGaN/GaN HFET photosensor with a p-GaInN optical gate greatly surpassed those of commercially available Si pin and Si avalanche photodiodes, and was comparable to those of photomultiplier tubes.
AlGaN Metal–Semiconductor–Metal Photodetectors on Planar and Epitaxial Laterally Overgrown AlN/Sapphire Templates for the Ultraviolet C Spectral Region
Authors: Knigge Andrea , Brendel Moritz , Brunner Frank , Einfeldt Sven , Knauer Arne , Kueller Viola , Zeimer Ute , Weyers Markus
Published: May 2013

Schottky type metal–semiconductor–metal (MSM) Al0.4Ga0.6N photodetectors (PDs) for the ultraviolet C spectral region on conventional planar AlN templates are compared with epitaxial laterally overgrown (ELO) AlN templates. On planar templates solar blind MSM PDs with state-of-the-art dark current in the pA range and a power independent responsivity are obtained. PDs on ELO templates with fingers parallel to the etched stripes have properties similar to those on planar templates. PDs on ELO templates with contact fingers oriented perpendicular to the etched stripe pattern exhibit photoconductive gain leading to external quantum efficiencies of up to 77 at 30 V applied bias surpassing that of the planar grown PDs by a factor of 100. In spite of the high gain these PDs also show low dark currents, short switching times and two operating regimes with power independent responsivity.
Passively Mode-Locked GaInN Laser Diode Generating 200 fs Optical Pulses
Authors: Kono Shunsuke , Watanabe Hideki , Koda Rintaro , Miyajima Takao , Kuramoto Masaru
Published: May 2013

Femtosecond optical pulses with a duration of 200 fs were generated using a GaInN bisectional laser diode passively mode-locked in a dispersion-compensated external cavity with spectral filtering performed outside the cavity. The fact that the femtosecond pulses were obtained with a negative intracavity group-velocity dispersion and a saturable absorber recovery time of about 15 ps indicates that the mechanism involved was soliton mode-locking. The spectro-temporal investigation of the output pulses directly emitted after the mode-locked laser diode revealed that the spectral broadening was due to self-phase modulation in the gain section.
Waveguide Optimization for Semipolar (In,Al,Ga)N Lasers
Authors: Rass Jens , Ploch Simon , Wernicke Tim , Frentrup Martin , Weyers Markus , Kneissl Michael
Published: May 2013

In this work the optical waveguiding in semipolar InGaN-based laser diodes is analyzed. Different designs of the separate confinement heterostructure with AlGaN or GaN cladding layers and GaN or InGaN waveguide layers are studied. The influence of waveguide material, thickness and composition on the optical confinement factor Γ, the accumulated strain energy E and the refractive index contrast is calculated. Measurements of the threshold and the far field intensity distributions of lasers with differing waveguide design confirm the predictions from model calculations. The optimum waveguide for a 410 nm single quantum well laser is found to consist of a symmetric In0.04Ga0.96N waveguide of 2×85 nm thickness with GaN cladding layers.
High In Composition InGaN for InN Quantum Dot Intermediate Band Solar Cells
Authors: Gómez Víctor J. , Rodriguez Paul E. D. Soto , Kumar Praveen , Calleja Enrique , Nötzel Richard
Published: May 2013

We report a detailed study of the growth of InGaN by plasma assisted molecular beam epitaxy. The In composition is around 55% providing the optimum bandgap in the near-infrared spectral region of the matrix material of quantum dot (QD) intermediate band solar cells. The layer thickness is 80 nm for sufficient absorption. Optimum growth conditions are identified at elevated N flux and reduced growth temperature for minimized phase separation and smooth surface morphology. On these optimized InGaN layers, InN QDs are grown exhibiting small size and high density. Optical emission is observed from both the InGaN layer and InN QDs.
Studies on Defect Reduction in AlGaN Heterostructures by Integrating an In-situ SiN Interlayer
Authors: Scholz Ferdinand , Forghani Kamran , Klein Martin , Klein Oliver , Kaiser Ute , Neuschl Benjamin , Tischer Ingo , Feneberg Martin , Thonke Klaus , Lazarev Sergey , Bauer Sondes , Baumbach Tilo
Published: May 2013

We have decreased the dislocation density in AlxGa1-xN epitaxial layers grown on sapphire wafers by introducing an in-situ deposited SiN nano-mask layer. Taking together results obtained by transmission electron microscopy, photoluminescence, cathodoluminescence, and X-ray diffraction, we were able to derive a schematic model about the AlGaN growth on the SiN nanomask: On the open pores of the nano-mask, Ga-rich AlGaN hillocks develop, whereas on the SiN layer Al-rich AlGaN nucleates owing to the reduced selectivity of Al-containing material. Once the hillocks are formed, Ga-rich material is more efficiently incorporated on the inclined side-facets leading to an Al-rich coverage of the centralc-plane part of the hillocks. We observed a bending of the dislocations towards the side-facets of the hillocks, which eventually leads to dislocation bundles with increased probability of dislocation annihilation, separated by fairly defect-free regions. Thus, we could achieve a significant reduction of the edge-type dislocation density in these epitaxial layers.
Orbital Angular Momentum Spectral Dynamics of GaN Excitons Excited by Optical Vortices
Authors: Shigematsu Kyohhei , Toda Yasunori , Yamane Keisaku , Morita Ryuji
Published: May 2013

We report on the coherent dynamics of the photoexcited orbital angular momentum (OAM) states of GaN excitons. The measurements were performed by a pump-probe four-wave mixing (FWM) using optical vortex (OV) pulses, where the pump OV pulse transfers its OAM to the center of mass momentum of excitons and the conversion of OAM via FWM with the probe pulse is detected. Especially, we performed analysis of the signal using an OAM-resolved spectroscopy, which allows us to evaluate the dephasing dynamics of excitons in time and space. The results indicate that near perfect conversion is achieved using the OV pulses with nonzero OAM and its spatial coherence remains high during the dephasing time, clearly indicating that the excitons keep the OAM transferred by the pump OV. In contrast, the component associated with the imperfect conversion becomes significant when one of the incident pulses intentionally includes an OAM-free component. The effect is clearly confirmed by the FWM excited by the pump with multiple OAM.
Design and Optical Characterization of Novel InGaN/GaN Multiple Quantum Well Structures by Metal Organic Vapor Phase Epitaxy
Authors: Zhang Liyang , Lieten Ruben R. , Latkowska Magdalena , Baranowski Michał , Kudrawiec Robert , Cheng Kai , Liang Hu , Borghs Gustaaf
Published: May 2013

Various multiple quantum well structures with three main geometries of triangular, isosceles trapezoidal, and right-angled trapezoidal shape have been designed and fabricated on 4-in. sapphire substrates by metal organic vapor phase epitaxy. Photoluminescence measurements reveal the influence of the quantum well structures on the emission wavelength and the internal quantum efficiency. We observe less decrease in the internal quantum efficiency with increasing emission wavelength for isosceles trapezoidal shaped structures with respect to conventional structures. A significant enhancement in efficiency of more than 50% is observed at 475 nm emission for the isosceles trapezoidal shaped structures compared to the conventional structures.
Effects of Chemical Treatments and Ultrathin Al2O3 Deposition on InAlN Surface Investigated by X-ray Photoelectron Spectroscopy
Authors: Akazawa Masamichi , Nakano Takuma
Published: May 2013

The effects of chemical treatments and Al2O3 deposition on the InAlN surface were investigated by X-ray photoelectron spectroscopy (XPS). Independent of the extent of native oxide removal, the In 4d core-level binding energy was the same for untreated, HCl-treated, and HF-treated InAlN. This indicated a strong pinning tendency of the Fermi level at the InAlN bare surface. However, a 300 meV decrease in the In 4d binding energy was observed after atomic layer deposition (ALD) of Al2O3, which indicated an increase in the negative surface potential at the InAlN surface. The reduction of positive charge at the InAlN surface is discussed.
Clay: New Opportunities for Tissue Regeneration and Biomaterial Design
Authors: Dawson Jonathan I. , Oreffo Richard O. C.
Published: May 2013

Seminal recent studies that have shed new light on the remarkable properties of clay interactions suggest unexplored opportunities for biomaterial design and regenerative medicine. Here, recent conceptual and technological developments in the science of clay interactions with biomolecules, polymers, and cells are examined, focusing on the implications for tissue engineering and regenerative strategies. Pioneering studies demonstrating the utility of clay for drug‐delivery and scaffold design are reviewed and areas for future research and development highlighted.
Optimal operation of process plants under partial shutdown conditions
Authors: Chong Zhiwen , Swartz Christopher L. E.
Published: May 2013

A systematic strategy for optimal plant operation during partial shutdowns is proposed. We consider the situation where one or more process units are shut down due to failure or maintenance but where the remaining units are able to continue operation to some degree. The goal of the strategy is to manipulate the plant degrees‐of‐freedom—during and after the shutdown—such that production is restored in a cost‐optimal fashion while meeting safety and operational constraints. Optimal control trajectories are obtained through the solution of a dynamic optimization problem. A novel multitiered optimization approach allows the prioritization of multiple competing objectives and the specification of trade‐offs between them. Uncertainty in the downtime estimate, a crucial parameter in shutdown optimization, is addressed through reoptimization. We employ a transient predictive control algorithm for implementing the computed control policy under feedback. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4151–4168, 2013
Synthesis and characterization of monodisperse uniformly shaped respirable aerosols
Authors: Fromen Catherine A. , Shen Tammy W. , Larus Abigail E. , Mack Peter , Maynor Benjamin W. , Luft J. Christopher , DeSimone Joseph M.
Published: May 2013

The top‐down, micromolding technique, referred to as Particle Replication in Nonwetting Templates (PRINT®), affords a new opportunity for the generation of inhalation therapeutics. Powders were fabricated with predetermined particle size and shape; when dispersed with a collision jet nebulizer, these particles resulted in monodisperse aerosols with geometric standard deviations well below 1.2. Dynamic shape factors for this novel set of uniformly shaped particles were determined by correcting the drag of nonspherical particles in the ultra‐Stokesian flow conditions of the aerodynamic particle sizer (APS). This convenient approach for shape factor determination agreed well with current literature approaches and allowed for the correction of APS results for particles with known volumes. Determined shape factor values of PRINT geometries were used to estimate the theoretical median aerodynamic diameters of individual aerosols, which were then compared to actual inhalation powders. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3184–3194, 2013
Line tension and contact angle of heterogeneous nucleation of binary fluids
Authors: Zhou Di , Zhang Fangfang , Mi Jianguo , Zhong Chongli
Published: May 2013

Due to its complexity, line tension is usually neglected or indirectly estimated in studying heterogeneous nucleation. In this work, we try to provide a direct and quantitative description of it. Within a three‐dimensional density functional framework, the total excess free energy and individual energies at different two‐phase interfaces are calculated during the droplet or bubble nucleation in binary fluids, and the line tension and contact angle are determined simultaneously. Meanwhile, the contact angle can also be measured directly from the spatial configuration of droplet or bubble. Comparing the calculated and measured contact angles, one can see that a good agreement is achieved for bubble and droplet at solvophilic and solvophobic walls. It is shown that line tension provides a considerable modification of contact angle prediction that is of great importance in engineering applications. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4390–4398, 2013
Distribution of topical agents to the paranasal sinuses: an evidence‐based review with recommendations
Authors: Thomas W. Walsh , Harvey Richard J. , Rudmik Luke , Hwang Peter H. , Schlosser Rodney J.
Published: May 2013

Background

The objective of this work was to review the literature concerning the distribution of topical therapeutics to the sinuses versus nasal cavity regarding: surgical state, delivery device, head position, and nasal anatomy and to provide evidence‐based recommendations.

Methods

A systematic review was conducted using Medline, EMBASE, and Cochrane databases to perform a Medical Subject Heading search of the literature from 1946 until the last week of May 2012. Articles were independently reviewed and graded for level of evidence. All authors came to consensus on recommendations through an iterative process.

Results

Recommendations were made for: improved sinus delivery with high‐volume devices and after standard sinus surgery. Recommendations were made against low‐volume delivery devices, such as drops, sprays, or simple nebulizers as they do not reliably reach the sinuses. If large‐volume devices are not tolerated, low‐volume devices are recommended using the lying head back or lateral head low positions to improve nasal cavity distribution to the middle meatus or olfactory cleft.

Conclusion

Surgery, volume of device, head position, and nasal anatomy were shown to impact distribution to the sinuses. Recommendations are made based upon this evidence as to how to best maximize therapeutic distribution to the sinuses.
Nichtproteinogene Aminosäurebausteine für Peptidgerüste aus nichtribosomalen Peptiden und hybriden Polyketiden
Authors: Walsh Christopher T. , O'Brien Robert V. , Khosla Chaitan
Published: May 2013

Frei vorkommende nichtproteinogene Aminosäuren sind schon lange wegen ihrer antimetabolen Eigenschaften bekannt. Entdeckt werden sie meist aufgrund der Reaktivität gegenüber der katalytischen Wirkung der Zielenzyme. Führt man sie regiospezifisch in biogene Peptide und Proteine ein, kann es möglich werden, eine neue Ära der Medizinalchemie an der Grenze zwischen kleinen und großen Wirkstoffen einzuleiten. Außerdem eröffnet die ortsspezifische Funktionalisierung von Proteinen besonders attraktive Strategien für die posttranslationale Proteinmodifizierung. Auch bieten viele der Aminosäuren, die von der Natur nicht für den Einbau in Proteine ausgewählt wurden, reiche architektonische Möglichkeiten bei Einführung in ribosomal hergestellte Polypeptide. Dieser Aufsatz fasst die Biosynthesewege zu den wichtigsten Klassen nichtkanonischer Bausteine und deren Stoffwechsellogik zusammen, die in nichtribosomalen Peptidgerüsten und nichtribosomalen Peptid‐Polyketid‐Hybriden resultieren.
Nonproteinogenic Amino Acid Building Blocks for Nonribosomal Peptide and Hybrid Polyketide Scaffolds
Authors: Walsh Christopher T. , O'Brien Robert V. , Khosla Chaitan
Published: May 2013

Freestanding nonproteinogenic amino acids have long been recognized for their antimetabolite properties and tendency to be uncovered to reactive functionalities by the catalytic action of target enzymes. By installing them regiospecifically into biogenic peptides and proteins, it may be possible to usher a new era at the interface between small molecule and large molecule medicinal chemistry. Site‐selective protein functionalization offers uniquely attractive strategies for posttranslational modification of proteins. Last, but not least, many of the amino acids not selected by nature for protein incorporation offer rich architectural possibilities in the context of ribosomally derived polypeptides. This Review summarizes the biosynthetic routes to and metabolic logic for the major classes of the noncanonical amino acid building blocks that end up in both nonribosomal peptide frameworks and in hybrid nonribosomal peptide‐polyketide scaffolds.
Melt spinning of PVDF fibers with enhanced β phase structure
Authors: Guo Zengwei , Nilsson Erik , Rigdahl Mikael , Hagström Bengt
Published: May 2013

Polyvinylidene fluoride (PVDF) fibers with a high amount of β phase crystal structure were prepared by melt spinning. With this technique, the cold drawing process is critical and efficient when aiming for a high amount of β phase. During the cold drawing process, more than 80% of the originally formed α phase crystal structure was converted into the β phase structure. In addition, the incorporation of 0.01 wt % of amino‐modified double wall carbon nanotube (NH2‐DWCNT) could further enhance the β phase content in the PVDF fibers. FTIR and DSC studies showed that the addition of NH2‐DWCNT to PVDF fibers could increase both the total crystallinity and β phase fraction in PVDF. The addition of nanoclay was found to be less efficient in this respect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2603–2609, 2013
How much sampling does it take to detect trends in coral‐reef habitat using photoquadrat surveys?
Authors: Molloy P.P. , Evanson M. , Nellas A.C. , Rist J.L. , Marcus J.E. , Koldewey H.J. , Vincent A.C.J.
Published: May 2013

Coral‐reef managers must detect and reverse collapses in habitat and evaluate the success of such interventions. Since these responsibilities must be met with limited time and resources, methods used should balance statistical power with practical and logistical constraints.

Photoquadrat analysis is a commonly used method to survey coral habitats. This method, which involves photographing substratum along transects and digitally analysing habitat at points on the ‘photoquadrats’, affords efficiency in the field but is costly and requires extensive desk‐based analysis. It remains unclear what is the optimal combination of sampling units (points, photoquadrats and transects) needed to detect important trends in coral habitat.

Here, a dataset on Philippine coral‐reef habitats, collected using intensive photoquadrat surveys, was used to explore the reliability of using different numbers of points per photoquadrat, photoquadrats per transect and transects per site to detect spatial differences in habitat.

Results of leave‐some‐out analyses were compared with analysis of the complete dataset. Using fewer points per photoquadrat and fewer photoquadrats per transect caused little decline in ability to detect key trends, and lessened desk‐based time; reducing the number of photoquadrats also lessened field time. Using fewer transects reduced time requirements but at the expense of statistical reliability.

Prospective power analyses revealed that common rates of coral recovery could not be detected using even the most intensive photoquadrat protocols. This result implies that coral recoveries within protected areas might go undetected using standard surveying techniques.

Using fixed rather than randomly placed photoquadrats, or more sensitive indicators of habitat recovery than coral cover (e.g. coral surface area) may improve power to detect coral recoveries. Finally, protocols that minimize desk time rarely also minimize field time and vice versa, which highlights the need to prioritize different logistical constraints when designing methods.

Copyright © 2013 John Wiley & Sons, Ltd.
Conformation‐Controlled Electron Transport in Single‐Molecule Junctions Containing Oligo(phenylene ethynylene) Derivatives
Authors: Wang Le‐Jia , Yong Ai , Zhou Kai‐Ge , Tan Lin , Ye Jian , Wu Guo‐Ping , Xu Zhu‐Guo , Zhang Hao‐Li
Published: May 2013

Understanding the relationships between the molecular structure and electronic transport characteristics of single‐molecule junctions is of fundamental and technological importance for future molecular electronics. Herein, we report a combined experimental and theoretical study on the single‐molecule conductance of a series of oligo(phenylene ethynylene) (OPE) molecular wires, which consist of two phenyl–ethynyl–phenyl π units with different dihedral angles. The molecular conductance was studied by scanning tunneling microscopy (STM)‐based break‐junction techniques under different conditions, including variable temperature and bias potential, which suggested that a coherent tunneling mechanism takes place in the OPE molecular wires with a length of 2.5 nm. The conductance of OPE molecular junctions are strongly affected by the coupling strength between the two π systems, which can be tuned by controlling their intramolecular conformation. A cos2 θ dependence was revealed between the molecular conductance and dihedral angles between the two conjugated units. Theoretical investigations on the basis of density functional theory and nonequilibrium Green’s functions (NEGF) gave consistent results with the experimental observations and provided insights into the conformation‐dominated molecular conductance.
Synthesis, Properties, and Dispersion of Few‐Layer Graphene Fluoride
Authors: Grayfer Ekaterina D. , Makotchenko Viktor G. , Kibis Lidiya S. , Boronin Andrei I. , Pazhetnov Egor M. , Zaikovskii Vladimir I. , Fedorov Vladimir E.
Published: May 2013

We have fluorinated few‐layer graphene (FLG) by using a low‐temperature fluorination route with gaseous ClF3. The treatment process resulted in a new graphene derivative with a finite approximate composition of C2F. TEM studies showed that the product consisted of thin transparent sheets with no more than 10 fluorographene layers stacked together. Spectroscopic methods revealed a predominantly covalent nature of the CF bonds in the as‐synthesized product and we found no evidence for the existence of so‐called “semi‐ionic” CF bonds, as observed in bulk CxF. In contrast to the case of graphite and typical (thick) expanded graphites, fluorination of FLG did not lead to the intercalation of ClF3 molecules, owing to the lack of a 3D layered structure. The approximate “critical” number of graphene layers that were necessary to form a phase of intercalated compound was estimated to be more than 12, thus providing a “chemical proof” of the difference between the properties of few‐layered graphenes and bulk graphites. Fluorographene C2F was successfully delaminated into thinner layers in organic solvents, which is an important property for its integration into electronic devices, nanohybrids, etc.
Mutational analysis of conserved regions harboring catalytic triad residues of the levansucrase protein encoded by the lsc‐3 gene (lsc3) of Pseudomonas syringae pv. tomato DC3000
Authors: Mardo Karin , Visnapuu Triinu , Vija Heiki , Elmi Triin , Alamäe Tiina
Published: May 2013

Levansucrase encoded by the lsc‐3 (lsc3) gene at genomic locus PSPTOA0032 of Pseudomonas syringae pv. tomato DC3000 was mutationally analyzed. Altogether, 18 single‐amino‐acid mutants of 13 positions of Lsc3 were studied for catalytic properties, including production of fructooligosaccharides (FOS). Asp62, Asp219, and Glu303 were proved as members of the catalytic triad. Respective alanine replacement mutants were practically inactive with their kcat values reduced up to ∼130,000 times. Additionally, the requirements of Trp61, Gln301, and Arg304, located in conserved sequence blocks around the catalytic triad positions for the catalysis were shown. The catalytic significance of the position equivalent to Arg304 was shown for levansucrases for the first time. Replacement of Gln301 specifically affected the polymerizing ability of Lsc3. The Gln301Ala mutant was largely hydrolytic and produced 31 times less FOS than the wild type. Despite high conservation grades, Leu66, Pro220, Asp225, and His306 tolerated replacement well. Quantification of produced FOS showed a high biotechnological potential of Lsc3. Using 1 mg of Lsc3 protein, 15.4 g of FOS with a degree of polymerization from 3 to 7 can be synthesized in a 20 H reaction with 1,200 mM sucrose. Our expression system allowed us to produce up to 30 mg of Lsc3 protein from 1 L of induced culture of recombinant Escherichia coli.
Formally acknowledging donor‐cadaver‐patients in the basic and clinical science research arena
Authors: Benninger Brion
Published: May 2013

Historically, in the healthcare profession, cadaveric tissue has been predominantly used for teaching the architecture of the human body. It is respectful practice in scientific writing to acknowledge colleagues who have helped to collect/analyze data and prepare manuscripts; however, it appears that we have omitted to thank those that have donated themselves for any of these projects to occur. The objective of this study was to investigate the formal acknowledgment thanking those who have given the amazing gift of themselves to science. A literature search was conducted on printed and electronic anatomical and clinical journals. Anatomical and clinical conferences were attended between 2008 and 2012; posters utilizing cadaveric tissue were examined for acknowledgment. University/private institutions were contacted to ascertain if memorial services were held. Literature revealed only one journal that required acknowledgment when donor‐cadaver's (DC's) were used. Poster examination revealed very few acknowledgments of DC tissue at clinical conferences. While all university programs (n = 20) held memorial services, only 6 of 20 private procurement organizations had any such event. Our surgical anatomist forefathers faced awkward conditions because cadaveric tissue was not readily available. Contemporarily, anatomists and researchers have ready access to DC's. Socially, these donations are recognized as unparalleled educational tools and gifts, yet often they are not given the appropriate recognition and are overlooked in the publishing and scientific research arena. This research suggests editors, researchers, IRB committees, nonprofit body willed programs, and for‐profit procurement organizations formally recognize and/or require recognition of those who donate their bodies for research. Clin. Anat. 26:810–813, 2013. © 2013 Wiley Periodicals, Inc.