bluuebunny/crossref_metadata_2025 huggingface dataset:
Semiconductor Nanowire Growth and Integration
Authors: Chen Lin , Lu Wei , Lieber Charles M.
Published: December 2014

Semiconductor nanowires refer to crystal structures with diameters as small as a few nanometers and lengths up to tens of micrometers or even millimeters. Nanowires can be produced either through conventional subtractive nanofabrication processes, via lithography and etching, or through additive nanomaterial growth methods. The quality of “top-down” fabricated nanowires are in principle determined by the starting material, although the size reduction techniques used to fabricate these structures inevitably introduce damage (e.g., roughness) that can degrade overall quality. The top-down approach, which relies heavily on the precision of the lithography and etching tools, also becomes less cost-effective when scaling to ca. 10 nm size regimes. In this chapter we focus on nanowires produced through “bottom-up” growth methods, in which the critical dimension (e.g. the nanowire diameter) is limited not by lithography precision but controlled during chemical synthesis with atomic resolution. In particular, the catalyst-mediated vapor–liquid–solid (VLS) process is discussed in detail since this approach enables the growth of a broad range of nanowire materials with controlled structure, morphology, composition, and doping.
High Performance, Low Power Nanowire Transistor Devices
Authors: Xiang Jie , Kim Ji Hun , Lu Wei
Published: December 2014

Nanowire field-effect transistors (NW-FETs) have been studied and developed by many research groups around the world as a promising candidate to sustain the relentless cadence of device scaling. Several key factors contributed to the boom of nanowire research. First, semiconductor nanowires can be prepared with reproducible electronic properties in high-yield, as required for large-scale integrated systems. Second, compared with “top-down” nanofabricated device structures, the “bottom-up” synthesized nanowire materials offer well-controlled size in at least one critical device dimension that is at or beyond the limits of lithography. In addition, the crystalline structure and smooth surfaces reduce scattering and result in higher carrier mobility compared with nanofabricated samples with similar size. Third, since the body thickness (diameter) of nanowires can be controlled down to well below 10 nm, the electrical integrity of nanowire-based electronics can be maintained even as the gate length is aggressively scaled, a feat that has become increasingly difficult to achieve in conventional MOSFETs. Lastly, the unique dimensions and composition control allows new transistor mechanisms that can transcend the traditional thermodynamic limit to a transistor off-state current, using quantum mechanical tunneling, impact ionization as well as nanoelectromechanical motions, which will be required to meet the power challenge facing the ever increasing computing demands of future decades.
Nanowires for Photovoltaics and Artificial Photosynthesis
Authors: Yang Peidong , Brittman Sarah , Liu Chong
Published: December 2014

As the world's population grows and modernizes, developing inexpensive and efficient technologies for solar energy conversion is becoming increasingly important. Photovoltaics and artificial photosynthesis are two approaches for transforming solar energy into a usable form, either electricity or chemical fuels. While both technologies have been actively researched for decades, semiconductor nanowires possess unique properties that make them promising candidates for efficient photovoltaics and artificial photosynthesis. Because many optical and electronic processes occur over nanometer length scales, nanowires can offer improved capabilities to absorb light, collect photogenerated charges, and perform chemical reactions, functions that are all essential for solar energy conversion. Additionally, the increasing dexterity with which scientists synthesize, fabricate, and integrate nanoscale structures suggests that efficient devices that can take full advantage of these unique properties are not too far in the future.
Nanowires for High-Performance Li-Ion Battery Electrodes
Authors: McDowell Matthew T. , Cui Yi
Published: December 2014

Lithium-ion batteries are widely used for mobile devices such as smartphones and laptops, but for new applications such as electric vehicles it is necessary to develop electrode materials with higher energy density, longer cycle life, and lower cost. Silicon is a particularly attractive high-capacity anode material, but large volume changes during lithiation/delithiation result in mechanical degradation and fast capacity decay. In this chapter, the development of Si NWs and other one-dimensional Si nanostructures for Li-ion battery anodes is presented. One-dimensional Si nanostructures show improved performance as anodes because (i) they can withstand volume changes without fracture, (ii) they can remain electrically connected to the current collector during cycling, and (iii) they can be engineered for stable solid electrolyte interphase formation. In addition to electrochemical performance, this chapter also discusses in situ studies that have revealed fundamental reaction and degradation mechanisms at the nanoscale. Finally, several other NW-based electrode materials are briefly discussed. Overall, NW-based electrode architectures show great promise for Li-ion batteries with improved performance.
Phononic and Electronic Engineering in Nanowires for Enhanced Thermoelectric Performance
Authors: Dechaumphai Edward , Moon Jaeyun , Wingert Matthew C. , Chen Renkun
Published: December 2014

In this chapter, we review recent developments pertaining to “nanowire thermoelectrics.” In particular, we focus on the fundamental aspects of engineering charge and heat transport properties in nanowires and its implications for thermoelectric applications. Specifically, we discuss the following topics in this chapter: general background of thermoelectrics and the relevant length scales related to thermoelectric transport; brief overview of main synthesis techniques for thermoelectric nanowires; thermal conductivity of semiconductor nanowires, including characterization techniques and measurement results; thermoelectric power factor measurements and results of semiconductor nanowires; approaches to assemble nanowires into bulk thermoelectric materials and devices; future outlook of possible strategies pertaining to nanowire thermoelectrics.
The formation of biodegradable micelles from a therapeutic initiator for enzyme-mediated drug delivery
Authors: Khuphe Mthulisi , Kazlauciunas Algy , Huscroft Martin , Thornton Paul D.
Published: December 2014

The direct grafting of amphiphilic macromolecules by sequentialn-carboxyanhydride ring-opening polymerisation (NCA ROP) from a therapeutic initiator enables the formation of monodisperse drug-containing micelles.
A facile and selective route to remarkably inert monocyclic NHC-stabilized boriranes
Authors: Braunschweig Holger , Claes Christina , Damme Alexander , Deißenberger Andrea , Dewhurst Rian D. , Hörl Christian , Kramer Thomas
Published: December 2014

The first monocyclic carbene-stabilised boriranes are prepared, and are found to be remarkably inert under forcing conditions despite their high ring strain.
Application of positron annihilation lifetime spectroscopy (PALS) to study the nanostructure in amphiphile self-assembly materials: phytantriol cubosomes and hexosomes
Authors: Dong Aurelia W. , Fong Celesta , Waddington Lynne J. , Hill Anita J. , Boyd Ben J. , Drummond Calum J.
Published: December 2014

Schematic of the mechanism of positron annihilation spectroscopy (PALS) showing (1) thermalisation (2) diffusion and (3) trapping and annihilation events.
Combining EXAFS spectroscopy and molecular dynamics simulations to understand the structural and dynamic properties of an imidazolium iodide ionic liquid
Authors: Migliorati Valentina , Serva Alessandra , Aquilanti Giuliana , Olivi Luca , Pascarelli Sakura , Mathon Olivier , D'Angelo Paola
Published: December 2014

An integrated approach combining EXAFS spectroscopy and molecular dynamics simulations has been applied to the study of liquid [C4mim]I.
Unusual solvent-dependent photophysical and self-assembly properties of NO2 substituted T-shaped phenazines
Authors: Lee Dong-Chan , Brownell Lacie V. , Jang Kyoungmi , Han Seung Ju , Robins Kathleen A.
Published: December 2014

The importance of NO2 substituent placement on T-shaped phenazines relative to electronic, photophysical, and organogelation properties.
Photoisomerisation of azobenzene crystals in aqueous dispersions examined by higher order derivative spectra
Authors: Ichimura Kunihiro
Published: December 2014

Higher order derivative spectra provide detailed information about the photoisomerisation behaviour of azobenzene even in the crystalline state.
Novel 2-alkyl-1-ethylpyridinium ionic liquids: synthesis, dissociation energies and volatility
Authors: Vilas Miguel , Rocha Marisa A. A. , Fernandes Ana M. , Tojo Emilia , Santos Luís M. N. B. F.
Published: December 2014

Overlapping of the electrostatic and van der Waals functional interaction potentials.
Correction: Green synthesis of stable Cu(0) nanoparticles onto reduced graphene oxide nanosheets: a reusable catalyst for the synthesis of symmetrical biaryls from arylboronic acids under base-free conditions
Authors: Hussain Najrul , Gogoi Pranjal , Azhaganand Vedi Kuyil , Shelke Manjusha V. , Das Manash R.
Published: December 2014

Correction for ‘Green synthesis of stable Cu(0) nanoparticles onto reduced graphene oxide nanosheets: a reusable catalyst for the synthesis of symmetrical biaryls from arylboronic acids under base-free conditions’ by Najrul Hussain et al., Catal. Sci. Technol., 2015, DOI: 10.1039/c4cy01229a
Ring-opening homo- and co-polymerization of lactides and ε-caprolactone by salalen aluminum complexes
Authors: Pilone Alessia , De Maio Nicolina , Press Konstantin , Venditto Vincenzo , Pappalardo Daniela , Mazzeo Mina , Pellecchia Claudio , Kol Moshe , Lamberti Marina
Published: December 2014

Salalen aluminum complexes gave isotactic polylactides from rac-LA, heterotactic polylactides from meso-LA and random copolymers of LA/CL. An experiment was designed to prove polymeryl exchange events.
Self-enhanced electrogenerated chemiluminescence of ruthenium(ii) complexes conjugated with Schiff bases
Authors: Li Panpan , Jin Zhaoyu , Zhao Meilian , Xu Yanxue , Guo Yong , Xiao Dan
Published: December 2014

Self-enhanced electrochemiluminescence based on ruthenium complexes conjugated with Schiff bases is studied and used for co-reactant free metal anion recognition.
Solution-processed ferroelectric terpolymer nanocomposites with high breakdown strength and energy density utilizing boron nitride nanosheets
Authors: Li Qi , Zhang Guangzu , Liu Feihua , Han Kuo , Gadinski Matthew R. , Xiong Chuanxi , Wang Qing
Published: December 2014

Ferroelectric polymer nanocomposites with boron nitride nanosheets exhibit greatly improved energy densities and higher charge–discharge efficiencies.
Nanotechnology: nature's gift or scientists' brainchild?
Authors: Hochella Michael F. , Spencer Michael G. , Jones Kimberly L.
Published: December 2014

The answer to the compelling question of whether nanomaterials are new or not is debated by leading scientists.
Zeolite synthesis in hydrated silicate ionic liquids
Authors: van Tendeloo Leen , Haouas Mohamed , Martens Johan A. , Kirschhock C. E. A. , Breynaert Eric , Taulelle Francis
Published: December 2014

Hydrated alkali silicate ionic liquids (HSIL) were prepared by hydrolysis of tetraethoxysilane (TEOS) in alkali hydroxide–water mixtures, inducing coacervation and phase separation. The resulting optically clear, homogenous silicate ionic liquid offers exceptional potential for monitoring zeolite crystallisation. This enhanced synthesis route provides access to analysis of speciation, mechanistic details of zeolite formation, and brings organic-template-free zeolite synthesis by design within reach.
The effect of low or high molecular weight oat beta-glucans on the inflammatory and oxidative stress status in the colon of rats with LPS-induced enteritis
Authors: Wilczak Jacek , Błaszczyk Katarzyna , Kamola Dariusz , Gajewska Małgorzata , Harasym Joanna Paulina , Jałosińska Małgorzata , Gudej Sylwia , Suchecka Dominika , Oczkowski Michał , Gromadzka-Ostrowska Joanna
Published: December 2014

Effect of oat beta-glucans on colon of rats.
A way to prepare a liposoluble natural pink colourant
Authors: Saldanha do Carmo C. , Nunes A. N. , Serra Ana Teresa , Ferreira-Dias S. , Nogueira I. , Duarte Catarina M. M.
Published: December 2014

The modelling and development of a lipophilic natural pink colourant derived from Opuntia spp. was studied using a green technology – PGSS® (Particles from Gas-Saturated Solutions).
Investigation of the role of lignin in biphasic xylan hydrolysis during dilute acid and organosolv pretreatment of corn stover
Authors: Mittal Ashutosh , Vinzant Todd B. , Brunecky Roman , Black Stuart K. , Pilath Heidi M. , Himmel Michael E. , Johnson David K.
Published: December 2014

One of the key objectives of biomass pretreatment is to maximize the xylose yield.
A journey to uncharted territory: new technical frontiers in studying tumor–stromal cell interactions
Authors: Guldner Ian H. , Zhang Siyuan
Published: December 2014

The complexities of tumor–stroma interactions necessitate new means of analysis. This review details emerging imaging and genetic methods that hold promise to provide unprecedented insight into tumor–stroma crosstalk.
Microfluidic static droplet array for analyzing microbial communication on a population gradient
Authors: Jeong Heon-Ho , Jin Si Hyung , Lee Byung Jin , Kim Taesung , Lee Chang-Soo
Published: December 2014

Quorum sensing (QS) is a type of cell–cell communication using signal molecules that are released and detected by cells, which respond to changes in their population density.
Synthesis of 17-membered azalides from a 16-membered macrolide utilizing amide-selective silane reduction
Authors: Seki Atsushi , Mori Toshihiro , Sasaki Kouji , Takahashi Yoshiaki , Miyake Toshiaki , Akamatsu Yuzuru
Published: December 2014

Novel 17-membered azalides of N-methylated amine type were synthesized and their antibacterial activity was evaluated.
Nickel-responsive regulation of two novelHelicobacter pyloriNikR-targeted genes
Authors: Jones M. D. , Ademi I. , Yin X. , Gong Y. , Zamble D. B.
Published: December 2014

TheHelicobacter pyloritranscription factor NikR represses two novel gene targets in a nickel-dependent manner.
Oxidation of testosterone by permanganate and its implication in sports drug testing
Authors: Kuzhiumparambil Unnikrishnan , Watanabe Shimpei , Fu Shanlin
Published: December 2014

Adulteration of urine with permanganate can lead to depletion of testosterone and formation of new reaction products (4α,5α- and 4β,5β-dihydroxytestosterone).
The combined effect between Co and carbon nanostructures grown on cordierite monoliths for the removal of organic contaminants from the liquid phase
Authors: Costa Demétrio A. S. , Oliveira Aline A. S. , de Souza Patterson P. , Sapag Karim , Moura Flávia C. C.
Published: December 2014

Carbon nanostructures are able to pre-concentrate organic contaminants by adsorption while metal cores catalyze the oxidation via a heterogeneous Fenton-like mechanism.
A BODIPY-luminol chemiluminescent resonance energy-transfer (CRET) cassette for imaging of cellular superoxide
Authors: Bag S. , Tseng J.-C. , Rochford J.
Published: December 2014

Chemiluminescent resonance energy transfer is investigated for a BODIPY-luminol dyad demonstratingin cellulobiochemiluminescence with reactive oxygen species in activated splenocytes.
Conformational modulation of peptides using β-amino benzenesulfonic acid (SAnt)
Authors: Priya Gowri , Kotmale Amol S. , Chakravarty Debamitra , Puranik Vedavati G. , Rajamohanan Pattuparambil R. , Sanjayan Gangadhar J.
Published: December 2014

This communication describes the utility of the conformationally restricted aromatic β-amino acid (2-aminobenzenesulfonic acid, SAnt) for inducing various folding interactions in short peptides.
Tumor-targeting delivery of hyaluronic acid–platinum(iv) nanoconjugate to reduce toxicity and improve survival
Authors: Ling Xiang , Shen Yan , Sun Runing , Zhang Mengze , Li Chang , Mao Jinyin , Xing Jing , Sun Chunmeng , Tu Jiasheng
Published: December 2014

A HA-EDA–Pt(iv) nanoconjugate achieved tumor-targeted therapyviamultiple steps, such as EPR effect, receptor-mediated endocytosis and microenvironment-based drug release and reactivation.
Inorganic Chemistry Frontiers: home for cutting-edge research
Authors: Gao Song
Published: December 2014

Welcome to the first issue of Inorganic Chemistry Frontiers 2015
Sulfamethazine copper(ii) complexes as antimicrobial thermal stabilizers and co-stabilizers for rigid PVC: spectroscopic, thermal, and DFT studies
Authors: Mansour Ahmed M. , Mohamed Riham R.
Published: December 2014

Binary and ternary Cu(ii) complexes of the sulfamethazine antibacterial drug have been prepared, characterized, and tested for their antibacterial thermal stabilizer efficiency for PVC.
The effect of titanium in Li3V2(PO4)3/graphene composites as cathode material for high capacity Li-ion batteries
Authors: Choi Mansoo , Kang Kisuk , Kim Hyun-Soo , Lee Young Moo , Jin Bong-Soo
Published: December 2014

We report high capacity and rate capability of titanium-added Li3V2(PO4)3 (LVP) as a cathode material for lithium ion batteries (LIBs).
A single-beam-splitting technique combined with a calibration-free method for field-deployable applications using laser-induced breakdown spectroscopy
Authors: Xu Mingjun , Lin Qingyu , Yang Guang , Xu Tao , Zhang Tianlong , Wang Xu , Wang Shuai , Bian Fang , Duan Yixiang
Published: December 2014

In this work, a single-beam-splitting laser-induced breakdown spectroscopy (LIBS) technique using one single laser system is demonstrated.
Investigations on the luminescence of emission-tunable Ca10K(PO4)7:Eu2+, Sr2+, Mg2+ phosphors for white LEDs
Authors: Wang Yuchun , Li Hongyan , Zhang Rongrong , Zhan Maolin , Zhang Jia
Published: December 2014

Tunable emission has been obtained in the CKP:Eu2+, Sr2+, Mg2+ phosphors by adjusting the Sr2+ and Mg2+ contents.
Tailoring the dissolution rate enhancement of aminoglutethimide by functionalization of MCM-41 silica: a hydrogen bonding propensity approach
Authors: Mitran Raul-Augustin , Nastase Silviu , Matei Cristian , Berger Daniela
Published: December 2014

Chlorine ions can mediate the adsorption and enhance the dissolution release of aminoglutethimide from pristine and functionalized MCM-41 mesoporous silica.
One-pot synthesis of hierarchical SnO2 hollow nanospindles self-assembled from nanorods and their lithium storage properties
Authors: Yu Qingjiang , Wang Wenqi , Wang Huixin , Huang Yuewu , Wang Jinzhong , Gao Shiyong , Guo Fengyun , Zhang Xitian , Gao Hong , Wang Xuanzhang , Yu Cuiling
Published: December 2014

Novel hierarchical SnO2 hollow nanospindles self-assembled from nanorods have been successfully synthesized via a templating approach under hydrothermal conditions.
Enhanced electrochemical performance and thermal stability of a CePO4-coated Li1.2Ni0.13Co0.13Mn0.54O2 cathode material for lithium-ion batteries
Authors: Chen J. J. , Li Z. D. , Xiang H. F. , Wu W. W. , Cheng S. , Zhang L. J. , Wang Q. S. , Wu Y. C.
Published: December 2014

CePO4 coating via a simple precipitation method enhances the thermal stability of the layered Li1.2Ni0.13Co0.13Mn0.54O2 cathode material.
Lipid/detergent mixed micelles as a tool for transferring antioxidant power from hydrophobic natural extracts into bio-deliverable liposome carriers: the case of lycopene rich oleoresins
Authors: Mastrogiacomo Disma , Lenucci Marcello Salvatore , Bonfrate Valentina , Di Carolo Marialuisa , Piro Gabriella , Valli Ludovico , Rescio Leonardo , Milano Francesco , Comparelli Roberto , De Leo Vincenzo , Giotta Livia
Published: December 2014

Lipid/detergent mixed micelles promote and modulate the incorporation of carotenoids from natural oleoresins into bio-deliverable liposome carriers.
Facile one-pot synthesis of 4-substituted semicarbazides
Authors: Bogolubsky Andrey V. , Moroz Yurii S. , Mykhailiuk Pavel K. , Dmytriv Yurii V. , Pipko Sergey E. , Babichenko Liudmyla N. , Konovets Anzhelika I. , Tolmachev Andrey
Published: December 2014

A simple one-pot approach to 4-substituted semicarbazides allowed us to synthesize a 25 member library.
Tweaking anisotropic gold nanostars: covariant control of a polymer–solvent mixture complex
Authors: Kedia Abhitosh , Kumar Harsh , Kumar Pandian Senthil
Published: December 2014

A versatile polymer–binary solvent mixture based tweaking of gold stars enables them as excellent candidates for tunable SERS substrates.
Rapid, regioselective deuteration of dimethyl-2,2′-bipyridines via microwave-assistance
Authors: Neranon Kitjanit , Ramström Olof
Published: December 2014

Isotopically pure [D6]-dimethyl-2,2′-bipyridine derivatives were selectively and rapidly formed using microwave-assisted regioselective deuteration of the methyl moieties of the parent bipyridine in a deuterium oxide solution.
Single crystalline Cu2ZnSnS4 nanosheet arrays for efficient photochemical hydrogen generation
Authors: Li Bo-Jun , Yin Peng-Fei , Zhou Yu-Zhu , Gao Zhi-Ming , Ling Tao , Du Xi-Wen
Published: December 2014

We present a scalable route for the preparation of single crystalline Cu2ZnSnS4 nanosheet arrays on conductive glass substrate, and demonstrate this architecture as an effective photocathode for solar hydrogen production.
Tris-imidazolium and benzimidazolium ionic liquids: a new class of biodegradable surfactants
Authors: Al-Mohammed Nassir N. , Duali Hussen Rusnah Syahila , Alias Yatimah , Abdullah Zanariah
Published: December 2014

Factors that improved the biodegradation of surfactants have successfully used to prepare higher ordered biodegradable tris-imidazolium and benzimidazolium ionic liquids.
High affinity of p-sulfonatothiacalix[4]arene with phenanthroline-diium in aqueous solution
Authors: Wang Kui , Yang En-Cui , Zhao Xiao-Jun , Liu Yu
Published: December 2014

The molecular binding behavior of sulfonated calixarenes with phenanthroline-diium guests were systemically investigated. p-Sulfonatothiacalix[4]arene shows a high affinity with phenanthroline-diium guests in the order of magnitude of 105 M−1.
Long-range proton relay shows an inverse linear free energy relationship depending on the pKa of the hydrogen-bonded wire
Authors: Mai Binh Khanh , Kim Yongho
Published: December 2014

The long-range proton transfer dependence on the pKa of hydroxyl molecules in hydrogen (H)-bonded wires was investigated using quantum mechanical calculations.
Combining palladium complex and organic amine on graphene oxide for promoted Tsuji–Trost allylation
Authors: Zhao Qingshan , Zhu Yuanzhi , Sun Zhen , Li Yang , Zhang Guoliang , Zhang Fengbao , Fan Xiaobin
Published: December 2014

A palladium complex and a tertiary amine are combined on graphene oxide as a promoted and recyclable catalyst for Tsuji–Trost allylation.
A two-dimensional highly ordered mesoporous carbon/graphene nanocomposite for electrochemical double layer capacitors: effects of electrical and ionic conduction pathways
Authors: Lee Chang-Wook , Yoon Seung-Beom , Kim Hyun-Kyung , Youn Hee-Chang , Han Joah , Roh Kwang Chul , Kim Kwang-Bum
Published: December 2014

A 2D mesoporous carbon/graphene nanocomposite shows a very high power density of 135 kW kg−1 at an energy density of 60 W h kg−1.
Decreased adipogenesis and adipose tissue in mice with inactivated protein phosphatase 5
Authors: Jacob Wright , Rosenzweig Doron , Vázquez-Martin Cristina , Duce Suzanne L. , Cohen Patricia T. W.
Published: December 2014

Glucocorticoids play an important role in the treatment of inflammation and immune disorders, despite side effects, which include metabolic derangements such as central adiposity. These studies examine the role of protein phosphatase 5 (Ppp5) in glucocorticoid receptor (GR) complexes which mediate response to glucocorticoids. Mice homozygous for inactivated Ppp5 (Ppp5D274A/D274A) exhibit decreased adipose tissue surrounding the gonads and kidneys compared with wild-type mice. Adipocyte size is smaller, more preadipocytes/stromal cell are present in their gonadal fat tissue and differentiation of preadipocytes to adipocytes is retarded. Glucocorticoid levels are raised and the GR is hyperphosphorylated in adipose tissue of Ppp5D274A/D274A mice at Ser212 and Ser220 (orthologous to human Ser203 and Ser211) in the absence of glucocorticoids. Preadipocyte cultures from Ppp5D274A/D274A mice show decreased down regulation of Delta-like protein-1/preadipocyte factor-1, hyperphosphorylation of extra-cellular signal regulated kinase 2 (ERK2) and increased concentration of (sex determining region Y)-box 9 (SOX9), changes in a pathway essential for preadipocyte differentiation, which leads to decreased concentrations of the transcription factors CEBPβ and CEBPα necessary for the later stages of adipogenesis. The data indicate that Ppp5 plays a crucial role in modifying GR-mediated initiation of adipose tissue differentiation, suggesting that inhibition of Ppp5 may potentially be beneficial to prevent obesity during glucocorticoid treatment.
Identification of key binding site residues of MCT1 for AR-C155858 reveals the molecular basis of its isoform selectivity
Authors: Nancolas Bethany , Sessions Richard B. , Halestrap Andrew P.
Published: December 2014

The proton-linked monocarboxylate transporters (MCTs) are required for lactic acid transport into and out of all mammalian cells. Thus, they play an essential role in tumour cells that are usually highly glycolytic and are promising targets for anti-cancer drugs. AR-C155858 is a potent MCT1 inhibitor (Ki ~2 nM) that also inhibits MCT2 when associated with basigin but not MCT4. Previous work [Ovens, M.J. et al. (2010) Biochem. J. 425, 523–530] revealed that AR-C155858 binding to MCT1 occurs from the intracellular side and involves transmembrane helices (TMs) 7–10. In the present paper, we generate a molecular model of MCT4 based on our previous models of MCT1 and identify residues in the intracellular substrate-binding cavity that differ significantly between MCT4 and MCT1/MCT2 and so might account for differences in inhibitor binding. We tested their involvement using site-directed mutagenesis (SDM) of MCT1 to change residues individually or in combination with their MCT4 equivalent and determined inhibitor sensitivity following expression in Xenopus oocytes. Phe360 and Ser364 were identified as important for AR-C155858 binding with the F360Y/S364G mutant exhibiting >100-fold reduction in inhibitor sensitivity. To refine the binding site further, we used molecular dynamics (MD) simulations and additional SDM. This approach implicated six more residues whose involvement was confirmed by both transport studies and [3H]-AR-C155858 binding to oocyte membranes. Taken together, our data imply that Asn147, Arg306 and Ser364 are important for directing AR-C155858 to its final binding site which involves interaction of the inhibitor with Lys38, Asp302 and Phe360 (residues that also play key roles in the translocation cycle) and also Leu274 and Ser278.
Increased magnetocrystalline anisotropy in epitaxial Fe-Co-C thin films with spontaneous strain
Authors: Reichel L. , Giannopoulos G. , Kauffmann-Weiss S. , Hoffmann M. , Pohl D. , Edström A. , Oswald S. , Niarchos D. , Rusz J. , Schultz L. , Fähler S.
Published: December 2014

Rare earth free alloys are in focus of permanent magnet research since the accessibility of the elements needed for nowadays conventional magnets is limited. Tetragonally strained iron-cobalt (Fe-Co) has attracted large interest as promising candidate due to theoretical calculations. In experiments, however, the applied strain quickly relaxes with increasing film thickness and hampers stabilization of a strong magnetocrystalline anisotropy. In our study, we show that already 2 at. % of carbon substantially reduces the lattice relaxation leading to the formation of a spontaneously strained phase with 3% tetragonal distortion. In these strained (Fe0.4Co0.6)0.98C0.02 films, a magnetocrystalline anisotropy above 0.4 MJ/m3 is observed while the large polarization of 2.1 T is maintained. Compared to binary Fe-Co, this is a remarkable improvement of the intrinsic magnetic properties. In this paper, we relate our experimental work to theoretical studies of strained Fe-Co-C and find a very good agreement.
Multibody correlations in the hydrophobic solvation of glycine peptides
Authors: Harris Robert C. , Drake Justin A. , Pettitt B. Montgomery
Published: December 2014

Protein collapse during folding is often assumed to be driven by a hydrophobic solvation energy (ΔGvdw) that scales linearly with solvent-accessible surface area (A). In a previous study, we argued that ΔGvdw, as well as its attractive (ΔGatt) and repulsive (ΔGrep) components, was not simply a linear function of A. We found that the surface tensions, γrep, γatt, and γvdw, gotten from ΔGrep, ΔGatt, and ΔGvdw against A for four configurations of deca-alanine differed from those obtained for a set of alkanes. In the present study, we extend our analysis to fifty decaglycine structures and atomic decompositions. We find that different configurations of decaglycine generate different estimates of γrep. Additionally, we considered the reconstruction of the solvation free energy from scaling the free energy of solvation of each atom type, free in solution. The free energy of the isolated atoms, scaled by the inverse surface area the atom would expose in the molecule does not reproduce the γrep for the intact decaglycines. Finally, γatt for the decaglycine conformations is much larger in magnitude than those for deca-alanine or the alkanes, leading to large negative values of γvdw (−74 and −56 cal/mol/Å2 for CHARMM27 and AMBER ff12sb force fields, respectively). These findings imply that ΔGvdw favors extended rather than compact structures for decaglycine. We find that ΔGrep and ΔGvdw have complicated dependencies on multibody correlations between solute atoms, on the geometry of the molecular surface, and on the chemical identities of the atoms.
Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions
Authors: Rinne Klaus F. , Gekle Stephan , Netz Roland R.
Published: December 2014

Using extensive equilibrium molecular dynamics simulations we determine the dielectric spectra of aqueous solutions of NaF, NaCl, NaBr, and NaI. The ion-specific and concentration-dependent shifts of the static dielectric constants and the dielectric relaxation times match experimental results very well, which serves as a validation of the classical and non-polarizable ionic force fields used. The purely ionic contribution to the dielectric response is negligible, but determines the conductivity of the salt solutions. The ion-water cross correlation contribution is negative and reduces the total dielectric response by about 5%-10% for 1 M solutions. The dominating water dielectric response is decomposed into different water solvation shells and ion-pair configurations, by this the spectral blue shift and the dielectric decrement of salt solutions with increasing salt concentration is demonstrated to be primarily caused by first-solvation shell water. With rising salt concentration the simulated spectra show more pronounced deviations from a single-Debye form and can be well described by a Cole-Cole fit, in quantitative agreement with experiments. Our spectral decomposition into ionic and different water solvation shell contributions does not render the individual contributions more Debye-like, this suggests the non-Debye-like character of the dielectric spectra of salt solutions not to be due to the superposition of different elementary relaxation processes with different relaxation times. Rather, the non-Debye-like character is likely to be an inherent spectral signature of solvation water around ions.
Structural study and ferroelectricity of epitaxial BaTiO3 films on silicon grown by molecular beam epitaxy
Authors: Mazet L. , Bachelet R. , Louahadj L. , Albertini D. , Gautier B. , Cours R. , Schamm-Chardon S. , Saint-Girons G. , Dubourdieu C.
Published: December 2014

Integration of epitaxial complex ferroelectric oxides such as BaTiO3 on semiconductor substrates depends on the ability to finely control their structure and properties, which are strongly correlated. The epitaxial growth of thin BaTiO3 films with high interfacial quality still remains scarcely investigated on semiconductors; a systematic investigation of processing conditions is missing although they determine the cationic composition, the oxygen content, and the microstructure, which, in turn, play a major role on the ferroelectric properties. We report here the study of various relevant deposition parameters in molecular beam epitaxy for the growth of epitaxial tetragonal BaTiO3 thin films on silicon substrates. The films were grown using a 4 nm-thick epitaxial SrTiO3 buffer layer. We show that the tetragonality of the BaTiO3 films, the crystalline domain orientations, and SiO2 interfacial layer regrowth strongly depend on the oxygen partial pressure and temperature during the growth and on the post-deposition anneal. The ferroelectricity of the films, probed using piezoresponse force microscopy, is obtained in controlled temperature and oxygen pressure conditions with a polarization perpendicular to the surface.
Nonlinear electrophoresis at arbitrary field strengths: small-Dukhin-number analysis
Authors: Schnitzer Ory , Yariv Ehud
Published: December 2014

Smoluchowski’s formula for thin-double-layer electrophoresis does not apply for highly charged particles, where surface conduction modifies the electrokinetic transport in the electro-neutral bulk. To date, systematic studies of this nonzero Dukhin-number effect have been limited to weak fields. Employing our recent macroscale model [O. Schnitzer and E. Yariv, “Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction,” Phys. Rev. E 86, 021503 (2012)], valid for arbitrary Dukhin numbers, we analyze herein particle electrophoresis at small (but finite) Dukhin numbers; valid for arbitrary fields, this asymptotic limit essentially captures the practical range of parameters quantifying typical colloidal systems. Perturbing about the irrotational zero-Dukhin-number flow, we derive a linear scheme for calculating the small-Dukhin-number correction to Smoluchowski’s velocity. This scheme essentially amounts to the solution of a linear diffusion–advection problem governing the salt distribution in the electro-neutral bulk. Using eigenfunction expansions, we obtain a semi-analytic solution for this problem. It is supplemented by asymptotic approximations in the respective limits of weak fields, small ions, and strong fields; in the latter singular limit, salt polarization is confined to a diffusive boundary layer. With the salt-transport problem solved, the velocity correction is readily obtained by evaluating three quadratures, corresponding to the contributions of (i) electro- and diffuso-osmotic slip due to polarization of both the Debye layer and the bulk; (ii) a net Maxwell force on the electrical double layer; and (iii) Coulomb body forces acting on the space charge in the “electro-neutral” bulk. The velocity correction calculated based upon the semi-analytic solution exhibits a transition from the familiar retardation at weak fields to velocity enhancement at moderate fields; this transition is analytically captured by the small-ion approximation. At stronger fields, the velocity correction approaches a closed-form asymptotic approximation which follows from an analytic solution of the diffusive boundary-layer problem. In this régime, the correction varies as the 3/2-power of the applied field. Our small-Dukhin-number scheme, valid at arbitrary field strengths, naturally lends itself to a tractable analysis of nonlinear surface-conduction effects in numerous electrokinetic problems.
Numerical study on solutal Marangoni instability in finite systems with a miscibility gap
Authors: Wang Fei , Mukherjee Rajdip , Selzer Michael , Nestler Britta
Published: December 2014

Solutal Marangoni instability (SMI) is investigated both in 2D and 3D using a combined Cahn-Hilliard and Navier-Stokes model in a finite system. Fe-Sn is chosen as a representative alloy system since the phase diagram reveals a region with a miscibility gap, where two liquid phases, namely, the Fe-rich phase L1 and the Sn-rich phase L2, are in chemical equilibrium. In 3D, considering a perturbed liquid cylinder (L2 phase) with a length of λ and a radius of R0 embedded in the middle of a simulation box of λ × H × H (length × width × height) surrounded by the phase L1, we find that the perturbation induced Marangoni flow is either clockwise or anti-clockwise depending on the mean curvature difference between the convex and concave regions which is affected by the ratio of λ/R0. The critical ratio of λ/R0 for SMI is shown to be invariant for different Marangoni numbers as well as independent of the geometrical properties of the L1 phase. In 2D, a perturbed liquid pipe with a length of λ and a radius of R0 embedded in the middle of a simulation box of λ × H (length × height) is taken into account. Due to different curvature constitution, the critical ratio of λ/R0 for SMI depends on the height of the L1 phase.
Dehydration of multilamellar fatty acid membranes: Towards a computational model of the stratum corneum
Authors: MacDermaid Christopher M. , DeVane Russell H. , Klein Michael L. , Fiorin Giacomo
Published: December 2014

The level of hydration controls the cohesion between apposed lamellae of saturated free fatty acids found in the lipid matrix of stratum corneum, the outermost layer of mammalian skin. This multilamellar lipid matrix is highly impermeable to water and ions, so that the local hydration shell of its fatty acids may not always be in equilibrium with the acidity and relative humidity, which significantly change over a course of days during skin growth. The homeostasis of the stratum corneum at each moment of its growth likely requires a balance between two factors, which affect in opposite ways the diffusion of hydrophilic species through the stratum corneum: (i) an increase in water order as the lipid lamellae come in closer contact, and (ii) a decrease in water order as the fraction of charged fatty acids is lowered by pH. Herein molecular dynamics simulations are employed to estimate the impact of both effects on water molecules confined between lamellae of fatty acids. Under conditions where membrane undulations are energetically favorable, the charged fatty acids are able to sequester cations around points of contact between lamellae that are fully dehydrated, while essentially maintaining a multilamellar structure for the entire system. This observation suggests that the undulations of the fatty acid lamellae control the diffusion of hydrophilic species through the water phase by altering the positional and rotational order of water molecules in the embedded/occluded “droplets.”
Viscosity dependence of passage through a fluctuating bottleneck
Authors: Orgován Norbert , Rauscher Anna , Málnási-Csizmadia András , Derényi Imre
Published: December 2014

We generalize the model of a rate process involving the passage of an object through a fluctuating bottleneck. The rate of passage is considered to be proportional to a power function of the radius of the bottleneck with exponent α > 0. The fluctuations of the bottleneck are coupled to the motion of the surrounding medium and governed by Langevin dynamics. We show numerically and also explain analytically that for slow bottleneck fluctuations the long time decay rate of the process has a fractional power law dependence on the solvent viscosity with exponent α/(α + 2). The results are consistent with the experimental data on ligand binding to myoglobin, and might also be relevant to other reactions for which exponents between 0 and 1 were reported.
Experimental investigation on the steady and unsteady disturbances in a flat plate boundary layer
Authors: Sattarzadeh Sohrab S. , Fransson Jens H. M.
Published: December 2014

Recent experiments have shown that miniature vortex generators (MVGs) are coveted devices to stabilize unsteady disturbances in flat plate boundary layers and to delay the onset of turbulence by modulating the base flow in the spanwise direction. The spanwise modulation is a result from the non-modal transient growth of steady and spanwise periodic streamwise vortices being generated by the MVGs. The present experimental investigation aims at studying the transient growth of non-modal disturbances induced by a spanwise periodic array of MVGs and its stabilizing effect on non-linear unsteady disturbances in the boundary layer originating from planar Tollmien-Schlichting (TS) waves. Measurements consist of cross-stream planes at different downstream locations in the boundary layer and a spatio-temporal analysis of different modes of the disturbances is carried out. In the streaky boundary layer generated by the MVGs the fundamental spanwise mode, with the same wavelength as the MVG pairs in the array, and its first harmonic, both undergo transient growth whereas the higher harmonics decay immediately downstream of the array. In the unstable region formed in the wake of the MVG blades, i.e., just downstream of the array, a wide range of spanwise modes contributes to an initial growth in the energy of unsteady disturbances. Similar behavior is observed upstream of branch II position of the neutral stability curve where the unsteady disturbances undergo a second energy growth in the unstable region. It is shown that the spatial gradients of the base flow in the wall-normal and spanwise directions are contributing to the amplification and attenuation of the TS wave disturbances, respectively, in the streaky boundary layer.
Predicting critical temperatures of iron(II) spin crossover materials: Density functional theory plus U approach
Authors: Zhang Yachao
Published: December 2014

A first-principles study of critical temperatures (Tc) of spin crossover (SCO) materials requires accurate description of the strongly correlated 3d electrons as well as much computational effort. This task is still a challenge for the widely used local density or generalized gradient approximations (LDA/GGA) and hybrid functionals. One remedy, termed density functional theory plus U (DFT+U) approach, introduces a Hubbard U term to deal with the localized electrons at marginal computational cost, while treats the delocalized electrons with LDA/GGA. Here, we employ the DFT+U approach to investigate the Tc of a pair of iron(II) SCO molecular crystals (α and β phase), where identical constituent molecules are packed in different ways. We first calculate the adiabatic high spin-low spin energy splitting ΔEHL and molecular vibrational frequencies in both spin states, then obtain the temperature dependent enthalpy and entropy changes (ΔH and ΔS), and finally extract Tc by exploiting the ΔH/T − T and ΔS − T relationships. The results are in agreement with experiment. Analysis of geometries and electronic structures shows that the local ligand field in the α phase is slightly weakened by the H-bondings involving the ligand atoms and the specific crystal packing style. We find that this effect is largely responsible for the difference in Tc of the two phases. This study shows the applicability of the DFT+U approach for predicting Tc of SCO materials, and provides a clear insight into the subtle influence of the crystal packing effects on SCO behavior.
Anisotropic charged impurity-limited carrier mobility in monolayer phosphorene
Authors: Ong Zhun-Yong , Zhang Gang , Zhang Yong Wei
Published: December 2014

The room temperature carrier mobility in atomically thin 2D materials is usually far below the intrinsic limit imposed by phonon scattering as a result of scattering by remote charged impurities in its environment. We simulate the charged impurity-limited carrier mobility μ in bare and encapsulated monolayer phosphorene. We find a significant temperature dependence in the carrier mobilities (μ ∝ T−γ) that results from the temperature variability of the charge screening and varies with the crystal orientation. The anisotropy in the effective mass leads to an anisotropic carrier mobility, with the mobility in the armchair direction about one order of magnitude larger than in the zigzag direction. In particular, this mobility anisotropy is enhanced at low temperatures and high carrier densities. Under encapsulation with a high-κ overlayer, the mobility increases by up to an order of magnitude although its temperature dependence and its anisotropy are reduced.
Biased diffusion in tubes of alternating diameter: Analytical treatment in the case of strong bias
Authors: Zitserman Vladimir Yu. , Berezhkovskii Alexander M. , Antipov Anatoly E. , Makhnovskii Yurii A.
Published: December 2014

This paper is devoted to the effective transport coefficients of a particle in a tube of alternating diameter. Analytical expressions are derived for the effective mobility and diffusivity under strong bias conditions, i.e., in the limiting case where the external biasing force tends to infinity. The expressions give the transport coefficients as functions of the geometric parameters of the tube and the external force. They show that the effective diffusivity is a linear function of the square of the external force, whereas the effective mobility is independent of the force. The problem of finding effective transport coefficients in a tube of alternating diameter is too complex to be analyzed by conventional methods. Therefore, the expressions are derived in the framework of an intuition-based approach and validated by Brownian dynamics simulations. The obtained results extend a short list of available analytical expressions for the effective transport coefficients.
Transport and photoconduction characteristics of metal-graphene-4H-SiC(0001) heterojunction devices
Authors: Hosseini T. , Tomer D. , Rajput S. , Li L. , Kouklin N.
Published: December 2014

Vertically integrated graphene-semiconductor systems remain of significant technological importance for their promise to captivate new device physics and propel the development of advanced carbon-based opto-electronic devices. In this study, we carry out a series of bias-dependent transport, gate-dependent transport, and photoconduction measurements to probe the opto-electronic characteristics of metal-graphene-4H-SiC (0001) (Si-face) heterojunctions. The forward bias transport is found to deviate strongly from thermionic emission one as being controlled by the device circuitry and minority carrier injection mechanisms. An improved analytical model is offered and used to extract key junction parameters including series resistance of ∼80 kΩ, interface barrier height of ∼0.6 eV, and ideality factor of ∼6.1. The results of the photocurrent tests point to a light-assisted minority carrier injection as a key mechanism behind the photoconductive gain obtained in the devices subject to a weak, sub-bandgap cw-excitation.
One-dimensional modulation of the stripe in a surface phononic lattice: The effect on propagation of surface waves
Authors: Trzaskowska A. , Mielcarek S. , Wiesner M.
Published: December 2014

Brillouin light scattering was applied for the investigation of surface waves propagation in phononic materials made of a silicon substrate loaded with a permalloy layer and a modulated nanostructure of aluminum stripes. The results revealed the impact of one-dimensional modulation of the surface phononic crystal on the propagation of surface acoustic waves along the modulated aluminum stripes. The dispersion relation was experimentally and theoretically investigated. The new modes propagating in the investigated structure are localized in the stripes and are defined.