bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and electrical properties in the K1/2Bi1/2TiO3–K1/2Bi1/2ZrO3 solid solution (KBT–KBZ)
Authors: Bengagi M. , Morini F. , El Maaoui M. , Marchet P. 
Published: June 2012

AbstractThe present work is devoted to the study of the Zr4+/Ti4 substitution in the K1/2Bi1/2Ti(1–x)ZrxO3 solid solution (x = 0.0 to x = 1.0), based upon the K1/2Bi1/2TiO3 (KBT) ferroelectric compound. The tetragonal distortion of KBT is suppressed by this substitution and leads to the cubic compound K1/2Bi1/2ZrO3 (KBZ). These results agree with the values of the ionic radii of the Zr4+ and Ti4 ions ($r_{{\rm Ti}^{4 + } } $ = 0.605 Å and $r_{{\rm Zr}^{4 + } } $ = 0.72 Å). Close to KBT (x ≤ 0.05), the symmetry remains tetragonal. For higher values of x, the “a” lattice parameter (cubic indexing) follows Vegard's law, thus confirming the formation of a solid solution. The transformation from tetragonal to cubic proceeds via an intermediate pseudocubic symmetry (0.1 ≤ x < 0.5), for which the X‐ray diffraction peaks present small broadening and asymmetry. For x ≥ 0.5 and up to the KBZ compound (a ≈ 4.158 Å), the samples are cubic but some extra peaks are also observed, indicating the occurrence of a secondary phase. The microstructure shows fine‐grained ceramic samples for the first range, while for the KBZ‐rich range the grains are micrometer‐sized and associated to very small grains of the secondary phase. Piezoelectricity is observed for the tetragonal and pseudocubic range, the substitution quickly reducing the piezoelectric properties. The measurement of the dielectric properties revealed close to KBT a dielectric anomaly probably associated to the tetragonal–cubic phase transition. For the pseudocubic and cubic range, a broad dielectric anomaly is observed around 300 °C, corresponding to a relaxor behavior. magnified image
Transmission performance of a low‐loss metal–insulator–semiconductor plasmonic phase‐shift Bragg grating
Authors: Xiao Jing , Liu Jiansheng , Zheng Zheng , Bian Yusheng , Wang Guanjun , Li Shuna 
Published: June 2012

AbstractWe propose a plasmonics phase‐shift Bragg grating based on a metal–insulator–semiconductor structure in the wavelength range of 1400–1700 nm. The Bragg grating is formed by a periodic height variation of a semiconductor strip that is separated from a metal surface by a nanoscale insulator layer. Moreover, a phase‐shift structure was introduced in the middle of the Bragg grating. Simulation results demonstrate that the proposed structure exhibits good filtering characteristics with a strong field enhancement. The proposed phase‐shift Bragg grating could be used as an ultracompact filter and enable on‐chip integration of photonic circuits.
Resistive‐switching behavior and mechanism in copper‐nitride thin films prepared by DC magnetron sputtering
Authors: Zhu Wei , Zhang Xin , Fu Xiaoniu , Zhou Yongning , Luo Shengyun , Wu Xiaojing 
Published: June 2012

AbstractResistive random access memory (RRAM) devices are made by copper nitride films prepared by DC magnetron sputtering. After a forming process, the CuxN‐based RRAM devices show bipolar character with low operation voltage and distinguishable resistance ratio. The fitting results for the electrical measurements and the conducting atomic force microscope (CAFM) analysis indicate that resistive switching mechanism is consistent with the formation and rupture of conducting filaments. Simultaneously, the distribution of conducting filaments measured by CAFM reveals a promising potential to fabricate high‐density RRAM device by using this material. The mechanism of the formation of conducting filaments is discussed based on our results.
Efficient second harmonic generation by birefringent phase matching in femtosecond‐laser‐inscribed KTP cladding waveguides
Authors: Dong Ningning , Chen Feng , Vázquez de Aldana J. R. 
Published: June 2012

AbstractWe report on the fabrication of nonlinear KTiOPO4 (KTP) cladding waveguides by using femtosecond‐laser direct inscription. The produced guiding structures with a circular cross section of ∼100 μm diameter support good light confinement both for the visible and infrared, for TE and TM polarization. Under the 1064 nm pulsed fundamental pump beam, guided‐wave second harmonic generation (SHG) at 532 nm has been realized with an optical conversion efficiency as high as 45.6% (∼0.076% W–1 cm–2), which is three times the magnitude of the normalized efficiency obtained for “double‐line” KTP waveguides (fabricated with the aim of comparison), thus showing an intriguing potential as integrated frequency converters. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics simulation for infrared spectroscopy with intramolecular forces from electronic properties of on‐the‐fly quantum chemical calculations
Authors: Ueno Seiji , Tanimura Yoshitaka , Ten‐no Seiichiro 
Published: June 2012

AbstractWe calculated vibrational spectra by means of a molecular dynamics simulation which utilizes intramolecular forces from ab initio molecular orbital calculations for instantaneous configurations of each molecule. Intermolecular interactions were determined with conventional force fields. Calculated molecular orbitals from the time‐dependent, instantaneous molecular configurations were also used to evaluate dipole moment and partial charges. We examined the validity of the present approach by evaluating infrared spectra for liquid carbon dioxide and water. We could capture some important features of intramolecular vibrational spectra of molecular liquids by this method, albeit there is room for further improvement in the descriptions of intermolecular interactions, especially of hydrogen bond. Possible extensions for accurate intermolecular and intramolecular vibrational spectrum were discussed. © 2012 Wiley Periodicals, Inc.
Exploring new species on the [H, S, Se, Cl] potential energy surface
Authors: Hermoso Willian , Jaufeerally Naziah B. , Ramasami Ponnadurai , Ornellas Fernando R. 
Published: June 2012

AbstractThis investigation is concerned with the characterization of seleno‐sulfide‐halogen model systems, the isomerization processes, and the dissociation into diatomic fragment channels on the [H, S, Se, Cl] potential energy surface. Structural, energetic, and vibrational data were obtained at the CCSD(T) and MP2 levels of theory with the series of correlation consistent basis sets and extrapolated to the complete basis set (CBS) limit. For the frequencies, additional computations were performed to include the contribution of anharmonic effects, and for the determination of the heats of formation, important corrections incorporating core‐valence correlation effects and relativistic effects (scalar and spin‐orbit) were taken into account. CCSD(T)/CBS relative stability (kcal mol−1) follows the order: HSSeCl (0.0), HSeSCl (8.80), SSeHCl (23.52), and SeSHCl (25.87). The cis‐rotational barrier for the two lowest isomers is practically identical (10.14 and 10.09 kcal mol−1), whereas for the trans barrier, we obtained 9.25 (HSSeCl) and 8.45 (HSeSCl) kcal mol−1. Dissociation of HSSeCl (HSeSCl) into HS (HSe) + SeCl (SCl) requires 59.70 (56.30) kcal mol−1. For the most stable isomer, we predict a value of the heat of formation at 298.15 K of 2.53 kcal mol−1. One of the outcomes of this research is that the MP2 results are consistent with those of CCSD(T). The MP2 method turns out to be a reliable alternative for a first exploration of larger catenated species, although it accounts for a lesser fraction of correlation effects. © 2012 Wiley Periodicals, Inc.
Structure and energetics of cyclopropane carboxaldehyde
Authors: Trindle Carl , Bleda Erdi A. , Altun Zikri 
Published: June 2012

AbstractWe use the energies obtained by a focal point analysis including extrapolation from results with basis sets cc‐pVnZ and aug‐cc‐pVnZ with n up to 4 and correlation corrections through CCSD(T), to estimate thermodynamic functions for the syn and anti isomers of cyclopropane carboxaldehyde (CPCA). These agree with values obtained by well‐established thermochemical schemes CBS‐QB3 and G4. The structures obtained in these studies also conform to the best experimental determination of the rotational constants in the gas phase. The kinetics of gas phase interconversion of the syn‐ and anti‐isomers of CPCA have been studied by a chirped‐pulse dynamic rotational spectroscopy. Computational modeling of the internal rotational potential allows the estimate of the interconversion rates by statistical (RRKM) methods. RRKM rates using a range of barrier heights including a CBS‐Q estimate are more than 10× the rates deduced from the dynamical rotational spectra. This suggests that nonstatistical effects may be limiting the rate. Detailed study of the interconversion potential by a variant of the focal point analysis suggests that previous estimates of the barrier may be too low, and thus, the inferred rice‐ramsperger‐kassel‐marcus (RRKM) rate could be too high. These results cast some doubt on the presence of nonstatistical effects and suggest that molecular dynamics studies should be conducted to characterize the energy flow in detail. © 2013 Wiley Periodicals, Inc.
Pseudo jahn‐teller origin of bending distortions in renner‐teller molecules and its spectroscopic implications
Authors: Garcia‐Fernandez Pablo , Bersuker Isaac B. 
Published: June 2012

AbstractIn an important reverse of understanding we show that the Renner‐Teller effect (RTE) which has been considered as the driving force of bending instability of linear molecules in degenerate states, is in fact producing just a splitting of the degenerate term and softening the ground state, but not bending instability; all instabilities and distortions of linear molecules are due to, and only to the mixing with appropriate excited states in the pseudo Jahn‐Teller effect (PJTE). The proof of this statement is given analytically in a general way, and it is supported by previously reported ab initio calculations showing that the contribution of the PJTE to the bending is overwhelmingly larger than the RTE softening. We show also that this finding, in addition to rationalizing the origin of instability of linear molecules, has significant implications in the interpretation of their properties, in particular, dipole moments, rotational level positions, spectroscopic selection rules, and line intensities. © 2012 Wiley Periodicals, Inc.
Molecular dynamics study of uncharged bupivacaine enantiomers in phospholipid bilayers
Authors: Martini M. Florencia , Pickholz Mónica 
Published: June 2012

AbstractTo investigate the effects of the uncharged bupivacaine (BVC) on the properties of model membranes of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphatidylcholine (POPC), we have performed a series of molecular dynamics simulations. A very particular characteristic of the local anesthetic BVC, that is being discuss in the recent literature, is that their enantiomers R‐(+) (R‐BVC) and S‐(−) (S‐BVC) present different activities. In this way, we have studied both enantiomers in a POPC phospholipids bilayers at a high molar ratios [local anesthetic (LA):lipid of 1:3]. The simulations were able to capture important features of the BVC–phospholipid bilayer interactions: BVC molecules are found in the interior of the bilayer. The R‐BVC enantiomer follows a bimodal distribution with access to the water–lipid interface; while the S‐BVC is found, in more uniform distribution, at the hydrophobic region. A decrease in the acyl chain segment order parameters, SCD, compared to neat bilayers, is found. Furthermore, this behavior is more noticeable for the R‐BVC form. The found decrease in SCD is attributed to a larger accessible volume per lipid in the tail region. Our results could help to understand the higher toxicity of this enantiomer. © 2012 Wiley Periodicals, Inc.
Crystal structures and thermodynamic investigations of NaSc(BH4)4 from first‐principles calculations
Authors: Kim Ki Chul 
Published: June 2012

AbstractThe double cation borohydride NaSc(BH4)4 has a total H2 content of 12.67 wt.% and has been suggested as a potential candidate for hydrogen storage applications. This study reports first‐principles calculations of the structure and reaction thermodynamics of NaSc(BH4)4. The calculations indicate that NaSc(BH4)4 is decomposed into a mixture of ScB2, NaBH4, and Na2(B10H10) with H2 release of 9.3 wt.% at 118 K at a partial pressure of H2 of 100 bar. Reactant compositions that can destabilize NaSc(BH4)4 were evaluated. This effort identified four destabilization reactions that are predicted to have reaction thermodynamics for hydrogen release within the temperature range of 78–109 K. Even though the reactions conclusively produce undesired compounds, such as refractory materials or kinetically stable B12H12‐containing species, the thermodynamic study suggests a direction for improving the thermodynamics of double cation borohydride‐based systems being actively considered for hydrogen storage applications. © 2012 Wiley Periodicals, Inc.
Metabolic engineering: enabling technology for biofuels production
Authors: Tai Mitchell , Stephanopoulos Gregory N. 
Published: June 2012

AbstractThe biofuels industry is rapidly growing with the goal of providing a sustainable fuel alternative to petroleum products. However, two challenges persist in limiting current biofuels technologies as a viable alternative: (1) the cost of feedstock and (2) the quality of the fuel. Metabolic engineering shows the potential to overcome these two challenges, enabling the bioconversion of cheaper feedstocks into improved fuels in a sustainable and environmentally friendly manner. Metabolic engineering is the systematic attempt to understand, design, and engineer cellular metabolic networks using a wide range of interdisciplinary tools and strategies. It is rapidly emerging as the enabling technology behind the development of the next generation of biofuels. Several examples of current research demonstrate how metabolic engineering has begun to contribute both novel and creative solutions toward bringing promising biofuel technologies to fruition: production of higher chain alcohols, fermentation of lignocellulosic material, and production of fatty acid derivatives. © 2012 John Wiley & Sons, Ltd.This article is categorized under:

Bioenergy > Science and Materials
Energy and Development > Science and Materials
Wound Healing after Open Appendectomies in Adult Patients: A Prospective, Randomised Trial Comparing Two Methods of Wound Closure
Authors: Kotaluoto S. , Pauniaho S.‐L. , Helminen M. , Kuokkanen H. , Rantanen T. 
Published: June 2012

AbstractBackgroundThe skin is closed in open appendectomy traditionally with few interrupted nonabsorbable sutures. The use of this old method is based on a suggestion that this technique decreases wound infections. In pediatric surgery, skin closure with running intradermal absorbable sutures has been found to be as safe as nonabsorbable sutures, even in complicated cases. Our purpose was to compare the safety of classic interrupted nonabsorbable skin closure to continuous intradermal absorbable sutures in appendectomy wounds in adult patients.MethodsA total of 206 adult patients with clinically suspected appendicitis were allocated to the study and prospectively randomized into two groups of wound closure: the interrupted nonabsorbable (NA) suture and the intradermal continuous absorbable (A) suture group. Primary wound healing was controlled on the first postoperative day, at 1 week clinically and after 2 weeks by means of a telephone interview. Follow‐up data were obtained from 185 patients (90 in group NA and 95 in group A).ResultsContinuous absorbable intradermal suturing was as safe as nonabsorbable sutures in regard to wound infections.ConclusionContinuous, absorbable sutures can be used safely even in complicated appendicectomies without increasing the risk of wound infection. Considering the benefits of absorbable suturing, we recommend this method in all open appendectomies.
Enzyme replacement therapy for mucopolysaccharidosis VI: long‐term cardiac effects of galsulfase (Naglazyme®) therapy
Authors: Braunlin E. , Rosenfeld H. , Kampmann C. , Johnson J. , Beck M. , Giugliani R. , Guffon N. , Ketteridge D. , Sá Miranda C. M. , Scarpa M. , Schwartz I. V. , Leão Teles E. , Wraith J. E. , Barrios P. , Dias da Silva E. , Kurio G. , Richardson M. , Gildengorin G. , Hopwood J. J. , Imperiale M. , Schatz A. , Decker C. , Harmatz P. ,   MPS VI Study Group
Published: June 2012

AbstractCharacteristic cardiac valve abnormalities and left ventricular hypertrophy are present in untreated patients with mucopolysaccharidosis type VI (MPS VI). Cardiac ultrasound was performed to investigate these findings in subjects during long‐term enzyme replacement therapy (ERT) with recombinant human arylsulfatase B (rhASB, rhN‐acetylgalactosamine 4‐sulfatase, galsulfase, Naglazyme®). Studies were conducted in 54 subjects before ERT was begun and at specific intervals for up to 96 weeks of weekly infusions of rhASB at 1 mg/kg during phase 1/2, phase 2, and phase 3 trials of rhASB. At baseline, mitral and aortic valve obstruction was present and was significantly greater in those ≥12 years of age. Mild mitral and trace aortic regurgitation were present, the former being significantly greater in those <12 years. Left ventricular hypertrophy, with averaged z‐scores ranging from 1.6–1.9 SD greater than normal, was present for ages both <12 and ≥12 years. After 96 weeks of ERT, ventricular septal hypertrophy regressed in those <12 years. For those ≥12 years, septal hypertrophy was unchanged, and aortic regurgitation increased statistically but not physiologically. Obstructive gradients across mitral and aortic valves remained unchanged. The results suggest that long‐term ERT is effective in reducing intraventricular septal hypertrophy and preventing progression of cardiac valve abnormalities when administered to those <12 years of age.
Colloidal stability of polymeric nanoparticles in biological fluids
Authors: Lazzari Stefano , Moscatelli Davide , Codari Fabio , Salmona Mario , Morbidelli Massimo , Diomede Luisa 
Published: June 2012

Abstract
Estimating the colloidal stability of polymeric nanoparticles (NPs) in biological environments is critical for designing optimal preparations and to clarify the fate of these devices after administration. To characterize and quantify the physical stability of nanodevices suitable for biomedical applications, spherical NPs composed of poly-lactic acid (PLA) and poly-methyl-methacrylate (PMMA), in the range 100–200 nm, were prepared. Their stability in salt solutions, biological fluids, serum and tissue homogenates was analyzed by dynamic light scattering (DLS). The PMMA NPs remained stable in all fluids, while PLA NPs aggregated in gastric juice and spleen homogenate. The proposed stability test is therefore useful to see in advance whether NPs might aggregate when administered in vivo. To assess colloidal stability ex vivo as well, spectrophotofluorimetric analysis was employed, giving comparable results to DLS.
Adventitious sprouting enables the invasive annual herb Euphorbia geniculata to regenerate after severe injury
Authors: Malíková Lenka , Mudrák Ondřej , Klimešová Jitka 
Published: June 2012

AbstractEuphorbia geniculata, an annual weed of arable land native to America and invasive in subtropical and tropical regions, is able to regenerate from seeds and is also able to produce adventitious buds on the hypocotyl. Whether sprouting from adventitious buds represents a mechanism for surviving severe injury, and whether this ability is crucial for species invasion is, however, not known. The significance of such sprouting was investigated with a field survey and a pot experiment. Among 897 plants in 25 field populations surveyed in Indonesia, only a few exhibited marks of injury and sprouting from adventitious buds. When seeds were collected from 12 of the populations and used in a pot experiment, however, the seedlings were able to survive severe injury (removal of all tissue above the hypocotyl) by sprouting from adventitious buds on the hypocotyl and were able to set seed, although they produced less vegetative and generative (flowers and fruits) biomass than control plants. Growth but not fitness of plants in the pot experiment was population specific but neither growth characteristic correlated with disturbance level assessed in the field. Although the pot experiment indicates that E. geniculata can cope with severe injury by adventitious sprouting from the hypocotyl, the survey data are inconsistent with the hypothesis that such adventitious sprouting is important for the plant's invasion in tropical regions.
Alkanol‐Induced Micelles of a Very Hydrophilic EO–PO–EO Block Copolymer: Characterization by Spectral and Scattering Methods
Authors: Parmar Arpan , Bharatiya Bhavesh , Patel Keyur , Aswal Vinod , Bahadur Pratap 
Published: June 2012

AbstractThe aqueous solution behavior of a PEO–PPO–PEO block copolymer (EO103PO39EO103), was investigated in the presence of aliphatic alkanols (C2, C4, C6 and C8). The non‐associated polymer chains remain extremely hydrated in water, but aggregation in the form of spherical micelles was evidenced, triggered by the interaction of polymer chains with hydrophobic alkanol. We assume that the hydrophobic interaction between the PPO block of the copolymer and alkanol promotes micellization, which increases further with the introduction of higher chain length species. The critical micellization temperature (CMT), as measured by UV–visible spectroscopy, indicates an interaction of polymer chains with the alkanol bearing a higher chain length, which triggers aggregation. The micelles were characterized by small angle neutron scattering to elucidate the size and related micellar parameters. The gradual increase in the alkanol content increases the aggregation number, though the micelles were spherical in shape. We conclude that ethanol, due to its preferential solubility in the aqueous phase, does not affect the aggregation. The alkanols with chain lengths of C4–C8 chain, interact with the PPO block through hydrophobic interaction and shifts the CMTs to lower values. The combined effect of inorganic salt (NaCl) and alkanols show enhanced micellar properties.
Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants
Authors: Zhang Luqing , Shi Jinhui , Xu Anhou , Geng Bing , Zhang Shuxiang 
Published: June 2012

AbstractTwo environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF2)6CH2OCH2CH2OCOCH(SO3Na)CH2COOH (FEOS‐1) and H(CF2)6CH2(OCH2CH2)3OCOCH(SO3Na)CH2COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, 1H NMR, 13C NMR and 19F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m−1 at 10.25 mmol L−1 and 21.63 mN m−1 at 8.33 mmol L−1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (Kp) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C7F15SO3Na, Kp = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.