bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, conformation transition, liquid crystal phase, and self‐assembled morphology of thermosensitive homopolypeptide
Authors: Liao Ye , Dong Chang‐Ming 
Published: February 2012

AbstractThermosensitive diethylene glycol‐derived poly(L‐glutamate) homopolypeptides (i.e., poly‐L‐EG2‐Glu) with different molecular weights (MW) (Mn,GPC = 5380–32520) were synthesized via the ring‐opening polymerization (ROP) of EG2‐L‐glutamate N‐carboxyanhydride (EG2‐Glu‐NCA) in N,N‐dimethylformamide solution at 50 °C. Their molecular structure, conformation transition, liquid crystal (LC) phase behavior, lower critical solution temperature (LCST) transition, and morphology evolution were thoroughly characterized by means of FTIR, 1H NMR, gel permeation chromatography, differential scanning calorimetry, wide angle X‐ray diffraction, polarized optical microscope, transmission electron microscope, and dynamic light scattering. In solid state, the homopolypeptide poly‐L‐EG2‐Glu presented a conformation transition from α‐helix to β‐sheet with increasing their MW at room temperature, while it mainly assumed an α‐helix of 80–86% in aqueous solution. Poly‐L‐EG2‐Glu showed a thermotropic LC phase with a transition temperature of about 100 °C in solid state, while it gave a reversible LCST transition of 34–36 °C in aqueous solution. The amphiphilic homopolypeptide poly‐L‐EG2‐Glu self‐assembled into nanostructures in aqueous solution, and their critical aggregation concentrations decreased with increasing MW. Interestingly, their morphology changed from spherical micelles to worm‐like micelles, then to fiber micelles with increasing MW. This work provides a simple method for the generation of different nanostructures from a thermosensitive biodegradable homopolypeptide. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Supramolecular star polymers with compositional heterogeneity
Authors: Gadwal Ikhlas , De Swati , Stuparu Mihaiela C. , Amir Roey J. , Jang Se Gyu , Khan Anzar 
Published: February 2012

AbstractWe present the synthesis of supramolecular star polymers with heterogeneous chemical compositions through potassium cation‐templated assembly of guanosine end‐functionalized random, diblock, and Y‐shaped copolymers. The assembly and disassembly processes of the synthesized star polymers have been systematically examined on changing the concentration, the temperature, the solvent, and the amount of cation using 1H NMR, UV/vis, and CD spectroscopy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Hidden symmetries and integrability in higher dimensional rotating black hole spacetimes
Authors: Cariglia M. , Krtouš P. , Kubizňák D. 
Published: February 2012

AbstractThis is a short pedagogical introduction to the subject of Killing‐Stäckel and Killing–Yano tensors and their role in the integrability of various types of equations that are of physical interest in curved space‐time, the main application being higher dimensional rotating black holes with cosmological constant.
Branes and wrapping rules
Authors: Bergshoeff E.A. , Riccioni F. 
Published: February 2012

AbstractWe show that the solitonic branes of ten‐dimensional IIA/IIB string theory must satisfy, upon toroidal compactification, a specific wrapping rule in order to reproduce the number of half‐supersymmetric solitonic branes that follows from a supergravity analysis. The realization of this wrapping rule suggests that IIA/IIB string theory contains a whole class of so‐called “non‐standard” Kaluza‐Klein monopoles.
Using steric constraints to template an organic array on Si(111)‐7 × 7
Authors: McLean A. B. , Weymouth A. J. , Edge G. J. A. , Miwa R. H. , Srivastava G. P. 
Published: February 2012

AbstractWe show that the Si(111)‐7 × 7 surface reconstruction can be used to template an ordered array of 1,3,5‐trimethyl benzene (mesitylene) molecules. The disorder that normally derives from the multiplicity of admissible adsorption geometries, for small aromatic molecules on 7 × 7, is suppressed, and the molecules are found to occupy both halves of the 7 × 7 unit cell with equal probability. It is argued that a steric interaction, associated with the methyl groups, hinders nearest neighbor adsorption and this leads to the formation of an array that has the molecules at the corners of the 7 × 7 half unit cells. To understand the ordering kinetics we used: scanning tunneling microscopy to study site occupancy as a function of coverage, ab initio total energy calculation to study the stability of the attachment sites and kinetic Monte Carlo modeling to investigate the emergence of translational order in the overlayer.magnified image
When two mesitylene molecules adsorb in nearest neighbor bridging geometries on the 7 × 7 reconstruction, the hydrogen atoms located on the methyl groups interact. To reduce the interaction energy, the molecules form an ordered array that places each molecule at the corner of the half cell.
Iron segregation in silicon‐on‐insulator wafer with polysilicon interlayer
Authors: Yli‐Koski M. , Haarahiltunen A. , Hintsala J. , Savin H. 
Published: February 2012

AbstractWe have studied iron gettering from monocrystalline silicon device layer into polycrystalline silicon (polysilicon) interlayer in thick bonded silicon‐on‐insulator (SOI) wafers. The results show that the polysilicon interlayer acts as an efficient gettering layer for iron. The gettering takes place via both the segregation and precipitation although the dominant gettering mechanism is segregation at low contamination levels. The activation energy of the segregation coefficient between the monocrystalline silicon and the polysilicon interlayer was found to be Ea = 1.9 ± 0.2 eV.
Excitonic states and their wave functions in anisotropic materials: A computation using the finite‐element method and its application to AlN
Authors: Gil Bernard , Felbacq Didier , Guizal Brahim , Bouchitté Guy 
Published: February 2012

AbstractWe have computed the excitonic states in the case of cylindrical symmetry as a function of the anisotropy using the finite‐element method. The wave functions are also obtained and are presented for m = 0, the states coupled with the electromagnetic fields. We illustrate for instance that the state dominantly built from the 3d0 hydrogenic level has a non‐vanishing oscillator strength when the anisotropy increases. As an illustration we conclude our message by the application of that calculation to the interpretation of the 1s–2s splitting in the specific case of aluminum nitride using the predictions of very recent band‐structure calculations.
Instability of amorphous oxide semiconductors via carrier‐mediated structural transition between disorder and peroxide state
Authors: Nahm Ho‐Hyun , Kim Yong‐Sung , Kim Dae Hwan 
Published: February 2012

AbstractThe excited holes occupying the valence band tail (VBT) states in amorphous oxide semiconductors (AOS) are found to induce formation of meta‐stable ${\rm O}_{2}^{{\rm 2}- } $ peroxide defects. The VBT states are at least partly characterized by the O–O ppσ* molecular orbital, and the localized‐hole‐mediated lattice instability results in the formation of the peroxide defects. Along with the O–O bond formation, the ppσ* state is heightened up into the conduction bands, and two electrons are accordingly doped in the electronic ground state. The energy barrier from the ${\rm O}_{2}^{{\rm 2}- } $ peroxide state to the normal disorder state is found to be 0.97 eV in hybrid density functional theory. The hole‐mediated formation of the meta‐stable peroxide defects and their meta‐stability is suggested as an origin of the negative bias and/or illumination stress instability in AOS.
Interdecadal variability of the ENSO–North Atlantic Oscillation connection in boreal summer
Authors: Wu Zhiwei , Lin Hai 
Published: February 2012

AbstractUnderstanding the combined effect of El Niño–Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) is of great importance for climate seasonal prediction (extreme climate events in particular). Results in this study show that during the last hundred years (1900 to present), the ENSO–NAO connection experiences a notable interdecadal change in summer (June–August) according to a 21‐year sliding correlation between them, namely, from no significant correlation (uncoupling) before the mid‐1970s to a significant correlation (coupling) after the mid‐1970s. Comparison analysis between the coupling epoch (1977–1997) and the uncoupling epoch (1958–1976) shows that the most pronounced circulation anomalies take place over the extratropical North Pacific. Further analysis and numerical experiments suggest that a poleward‐propagating Rossby wave train, possibly enhanced by sea‐surface‐temperature anomalies in the extratropical North Pacific associated with the developing phases of ENSO during the later epoch, is responsible for connecting the ENSO signal with the NAO. © 2012 Crown in the right of Canada. Published by JohnWiley & Sons Ltd.
Spectroscopic parameter and molecular constant investigations for low‐lying electronic states of P ion
Authors: Wang Jie‐Min , Feng Heng‐Qiang , Sun Jin‐Feng 
Published: February 2012

AbstractThe potential energy curves (PECs) of three low‐lying electronic states of P ion, X2Πu, A2Σ, and B2Σ, have been studied using the full valence complete active space self‐consistent field method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach and MRCI with Davidson correction (+Q). The correlation‐consistent basis sets, aug‐cc‐pV5Z and aug‐cc‐pV6Z, are used and the total energies are extrapolated to the complete basis set limit. Using these PECs obtained with the MRCI+Q/56‐extrapolation, the spectroscopic parameters for these electronic states are determined and compared in detail with experimental data and those of previous studies reported in the literature. The comparison shows that excellent agreement exists between the present results and the available experiments. The first 40 vibrational states for the three electronic states are also computed when the rotational quantum number J equals zero. For each vibrational state, the vibrational level G(υ), inertial rotation constant Bυ, and centrifugal distortion constant Dυ are determined when J = 0, which are in good accord with the available measurements. © 2012 Wiley Periodicals, Inc.
Temperature dependence of the molecular conformations of dilauroyl phosphatidylcholine: A density functional study
Authors: Mineva Tzonka , Krishnamurty Sailaja , Salahub Dennis R. , Goursot Annick 
Published: February 2012

AbstractBorn–Oppenheimer molecular dynamics (BOMD) in combination with density functional theory, augmented with a damped empirical dispersion term, has been used to study the behavior of dilauroyl phosphatidylcholine (DLPC) isomers with temperature. In contrast to dimyristoyl phosphatidylcholine (DMPC), the BOMD results show the presence of various conformations at different temperatures. The molecular order–disorder process, quantified by the distance‐fluctuation criterion as a function of temperature, is characterized by two transitions. This is in line with the known two‐phase transitions of DLPC bilayers, involving trans to gauche conformational changes in the alkane chains. The different temperature dependence of the DLPC and DMPC molecules suggests that the experimentally observed unusual dynamics of DLPC bilayers compared to that of longer chain lipids is governed to a large extent by the intramolecular dynamics. A first‐principles methodology applied at the molecular level can thus be an appropriate tool for microscopic analysis of the order–disorder transitions, which are related to the molecular structural transformations within large assemblies. © 2012 Wiley Periodicals, Inc.
Characterizing optimal sampling of binary contingency tables via the configuration model
Authors: Blanchet Jose , Stauffer Alexandre 
Published: February 2012

AbstractA binary contingency table is an m × n array of binary entries with row sums r = (r1, …, rm) and column sums c = (c1, …, cn). The configuration model generates a contingency table by considering ri tokens of type 1 for each row i and cj tokens of type 2 for each column j, and then taking a uniformly random pairing between type‐1 and type‐2 tokens. We give a necessary and sufficient condition so that the probability that the configuration model outputs a binary contingency table remains bounded away from 0 as
\documentclass{article} \usepackage{mathrsfs} \usepackage{amsmath} \pagestyle{empty} \begin{document} \begin{align*}N=\sum_{i=1}^m r_i=\sum_{j=1}^n c_j\end{align*} \end{document}
goes to ∞. Our finding shows surprising differences from recent results for binary symmetric contingency tables. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 2012
Roughness Parameters for Standard Description of Surface Nanoarchitecture
Authors: Webb Hayden K. , Truong Vi Khanh , Hasan Jafar , Fluke Christopher , Crawford Russell J. , Ivanova Elena P. 
Published: February 2012

SummaryThe nanoarchitecture and surface roughness of metallic thin films prepared by magnetron sputtering were analyzed to determine the topographical statistics that give the optimum description of their nanoarchitechture. Nanoscale topographical profiles were generated by performing atomic force microscopy (AFM) scans of 1 μm × 1 μm areas of titanium and silver films of three different thicknesses (3 nm, 12 nm, and 150 nm). Of the titanium films, the 150‐nm film had the highest average roughness (Ra = 2.63 nm), more than four times that of the 3‐nm and 12‐nm titanium films. When silver films were coated on top of 150‐nm titanium films, the average roughness increased further; the 3‐nm (Ra = 4.96 nm) and 150‐nm (Ra = 4.65 nm) silver films average roughnesses were approximately twice that of the 150‐nm titanium film. For topographical analysis, seven statistical parameters were calculated. These parameters included commonly used roughness measurements, as well as some less commonly used measurements, in order to determine which combination of parameters gave the best overall description of the nanoarchitecture of the films presented. Skewness (Rskw), surface area increase (Rsa), and peak counts (Rpc) provided the best description of horizontal surface dimensions, and in conjunction with vertical descriptors Ra and Rq gave the best characterization of surface architecture. The five roughness parameters Ra, Rq, Rskw, Rsa, and Rpc are proposed as a new standard for describing surface nanoarchitecture. SCANNING 34: 257‐263, 2012. © 2012 Wiley Periodicals, Inc.
Fabricating Nanostructures Through a Combination of Nano‐Oxidation and Wet Etching on Silicon Wafers With Different Surface Conditions
Authors: Huang Jen‐Ching 
Published: February 2012

SummaryThis study investigates the surface conditions of silicon wafers with native oxide layers (NOL) or hydrogen passivated layers (HPL) and how they influence the processes of nano‐oxidation and wet etching. We also explore the combination of nano‐oxidation and wet etching processes to produce nanostructures. Experimental results reveal that the surface conditions of silicon wafers have a considerable impact on the results of nano‐oxidation when combined with wet etching. The height and width of oxides on NOL samples exceeded the dimensions of oxides on HPL samples, and this difference became increasingly evident with an increase in applied bias voltage. The height of oxidized nanolines on the HPL sample increased after wet etching; however, the width of the lines increased only marginally. After wet etching, the height and width of oxides on the NOL were more than two times greater than those on the HPL. Increasing the applied bias voltage during nano‐oxidation on NOL samples increased both the height and width of the oxides. After wet etching however, the increase in bias voltage appeared to have little effect on the height of oxidized nanolines, but the width of oxidized lines increased. This study also discovered that the use of higher applied bias voltages on NOL samples followed by wet etching results in nanostructures with a section profile closely resembling a curved surface. The use of this technique enabled researchers to create molds in the shape of a silicon nanolens array and an elegantly shaped nanoscale complex structures mold. SCANNING 34: 264‐270, 2012. © 2012 Wiley Periodicals, Inc.
The Fabrication and Preservation of Nanostructures on Silicon Wafers With a Native Oxide Layer
Authors: Huang Jen‐Ching , Wang Jui‐Yang 
Published: February 2012

SummaryThis study used nano‐oxidation lithography to create oxidized circular nanostructures on a silicon wafer with a native oxide layer (NOL). We also investigated the impact of wet etching on the size of circular oxidized nanostructures and examined how the method and duration of preservation affect them. Experimental results show that the height and width of oxidized circular nanostructures increase proportionally with applied voltage. After wet etching, an increase in applied voltage resulted in a marked increase in the width of the circular nanostructures, a decrease in the inner diameter, and little variation in height. We further demonstrated that in a moist environment, the oxidation process continues, resulting in a further increase in height and width. During the initial stages of preservation, these changes occurred rapidly; however, the increase was negligible after 30 days. We propose the concept of reaction area (RA) ratio to explain the above phenomenon and provide evidence to support these claims. Our results led us to a simple and yet effective method of preserving oxidized circular nanostructures, called the electrostatic patch preservation (EPP) method, to overcome problems associated with changes in size occurring during the preservation of silicon nanostructure molds. SCANNING 34: 347–356, 2012. © 2012 Wiley Periodicals, Inc.
Exploration and exploitation strategies, profit performance, and the mediating role of strategic learning: Escaping the exploitation trap
Authors: Sirén Charlotta A. , Kohtamäki Marko , Kuckertz Andreas 
Published: February 2012

AbstractThis study focuses on the role of strategic learning as a mediating construct between opportunity‐seeking (exploration) and advantage‐seeking (exploitation) strategies and profit performance. Prior studies argue that the effect of these core elements of strategic entrepreneurship (exploration and exploitation) cannot be fully captured through their direct effects on profit performance, but that this relationship consists of mediating factors. This study proposes that the process of strategic learning, through its intraorganizational elements that enable the dissemination, interpretation, and implementation of strategic knowledge, enables firms to capitalize on the benefits of both exploration and exploitation strategies. Results from 206 Finnish software firms indicate that strategic learning fully mediates the relationship between exploration, exploitation, and profit performance. The result contributes by stressing the importance of strategic learning processes, especially in conjunction with entrepreneurial exploration strategies. Furthermore, the study demonstrates that the effect from exploration to strategic learning is moderated by the level of exploitation. This moderation effect suggests that the strategic learning is limited, being a path dependent capability that favors exploitation over exploration when stretched. However, strategic learning effectively allows both types of strategies to improve profit performance. Copyright © 2012 Strategic Management Society.
Orientation Dependence of Martensitic Transformation in High Mn TRIP/TWIP Steels
Authors: Yang Ping , Liu Tong‐Yan , Lu Fa‐Yun , Meng Li 
Published: February 2012

AbstractOrientation dependence of transformation such as precipitation, allotropic transformation, martensitic transformation, or even twinning and recrystallization prevails strongly during dynamic transformation under deformation. Using mainly EBSD technique, this works reveals this behavior during tension and compression of high manganese TRIP/TWIP steels containing two types of martensites. The results show that this orientation dependence can lead to the differences in transformation kinetics, variant selection, the sizes, and orientations of new grains. These phenomena are ascribed to the influence of Schmid factor and strain accommodation in different deformation conditions.
An empirical methodology for human integration in the SE technical processes
Authors: Hardman Nicholas , Colombi John 
Published: February 2012

AbstractThis research examines quantitative methods to better integrate human considerations into early system design. Studies show that for human systems integration (HSI) concerns, systems engineers often rely on qualitative judgments or delay critical decisions until late in the system lifecycle; actions that have predictable cost, schedule, and performance consequences. Thus, empirical and quantifiable methods were pursued to improve the engineering of human HSI. These methods are mathematically rigorous, grounded in relevant theory, and apply human subjects data to critical systems development challenges. Their utility is demonstrated by application in support of three systems engineering activities: requirements elicitation, functional allocation, and user interface design. Together, they demonstrate a coherent approach to integrate human considerations into early system development—a key tenet of the INCOSE SE Handbook. © 2012 Wiley Periodicals, Inc. Syst Eng
Using a TRIZ framework for systems engineering trade studies
Authors: Blackburn Timothy D. , Mazzuchi Thomas A. , Sarkani Shahram 
Published: February 2012

AbstractIdentifying and appropriately resolving system tradeoffs or effectively evaluating alternatives is a key deliverable of systems engineering. Without proper resolution, system performance is hindered, or suboptimal technologies are chosen. TRIZ, the Theory of Inventive Problem Solving, offers tools and methods to identify and resolve tradeoffs (which it terms contradictions or conflicts). TRIZ recognizes that fundamental performance limits arise when one or more unresolved tradeoffs exist in a system. According to TRIZ, eliminating or reducing the effects of the conflicts is necessary to move to improved system performance. This paper presents a TRIZ Trade Study framework that is useful to identify system conflicts, both across alternatives and within a technology, and at various levels of requirements decomposition, to compare options and optimize how the system performs. The framework was developed to perform a trade study between alternative pharmaceutical production systems, and merges traditional trade study methodologies with classical TRIZ. Specifically, traditional pharmaceutical manufacturing development and manufacturing were traded against an emerging and proposed approach, QbD (Quality by Design). Given TRIZ is scalable and useful to a variety of systems, the application of the TRIZ Trade Study Framework is also broadly applicable across system scale and domains. © 2012 Wiley Periodicals, Inc. Syst Eng