bluuebunny/crossref_metadata_2025 huggingface dataset:
Antarctic archaea–virus interactions: metaproteome-led analysis of invasion, evasion and adaptation
Authors: Tschitschko Bernhard , Williams Timothy J , Allen Michelle A , Páez-Espino David , Kyrpides Nikos , Zhong Ling , Raftery Mark J , Cavicchioli Ricardo
Published: June 2015

Despite knowledge that viruses are abundant in natural ecosystems, there is limited understanding of which viruses infect which hosts, and how both hosts and viruses respond to those interactions—interactions that ultimately shape community structure and dynamics. In Deep Lake, Antarctica, intergenera gene exchange occurs rampantly within the low complexity, haloarchaea-dominated community, strongly balanced by distinctions in niche adaptation which maintain sympatric speciation. By performing metaproteomics for the first time on haloarchaea, genomic variation of S-layer, archaella and other cell surface proteins was linked to mechanisms of infection evasion. CRISPR defense systems were found to be active, with haloarchaea responding to at least eight distinct types of viruses, including those infecting between genera. The role of BREX systems in defending against viruses was also examined. Although evasion and defense were evident, both hosts and viruses also may benefit from viruses carrying and expressing host genes, thereby potentially enhancing genetic variation and phenotypic differences within populations. The data point to a complex inter-play leading to a dynamic optimization of host–virus interactions. This comprehensive overview was achieved only through the integration of results from metaproteomics, genomics and metagenomics.
In vivo nanoparticle-mediated radiopharmaceutical-excited fluorescence molecular imaging
Authors: Hu Zhenhua , Qu Yawei , Wang Kun , Zhang Xiaojun , Zha Jiali , Song Tianming , Bao Chengpeng , Liu Haixiao , Wang Zhongliang , Wang Jing , Liu Zhongyu , Liu Haifeng , Tian Jie
Published: June 2015

Cerenkov luminescence imaging utilizes visible photons emitted from radiopharmaceuticals to achieve in vivo optical molecular-derived signals. Since Cerenkov radiation is weak, non-optimum for tissue penetration and continuous regardless of biological interactions, it is challenging to detect this signal with a diagnostic dose. Therefore, it is challenging to achieve useful activated optical imaging for the acquisition of direct molecular information. Here we introduce a novel imaging strategy, which converts γ and Cerenkov radiation from radioisotopes into fluorescence through europium oxide nanoparticles. After a series of imaging studies, we demonstrate that this approach provides strong optical signals with high signal-to-background ratios, an ideal tissue penetration spectrum and activatable imaging ability. In comparison with present imaging techniques, it detects tumour lesions with low radioactive tracer uptake or small tumour lesions more effectively. We believe it will facilitate the development of nuclear and optical molecular imaging for new, highly sensitive imaging applications.
MoS2 Heterojunctions by Thickness Modulation
Authors: Tosun Mahmut , Fu Deyi , Desai Sujay B. , Ko Changhyun , Seuk Kang Jeong , Lien Der-Hsien , Najmzadeh Mohammad , Tongay Sefaattin , Wu Junqiao , Javey Ali
Published: June 2015

In this work, we report lateral heterojunction formation in as-exfoliated MoS2 flakes by thickness modulation. Kelvin probe force microscopy is used to map the surface potential at the monolayer-multilayer heterojunction and consequently the conduction band offset is extracted. Scanning photocurrent microscopy is performed to investigate the spatial photocurrent response along the length of the device including the source and the drain contacts as well as the monolayer-multilayer junction. The peak photocurrent is measured at the monolayer-multilayer interface, which is attributed to the formation of a type-I heterojunction. The work presents experimental and theoretical understanding of the band alignment and photoresponse of thickness modulated MoS2 junctions with important implications for exploring novel optoelectronic devices.
Pleistocene glaciations, demographic expansion and subsequent isolation promoted morphological heterogeneity: A phylogeographic study of the alpine Rosa sericea complex (Rosaceae)
Authors: Gao Yun-Dong , Zhang Yu , Gao Xin-Fen , Zhu Zhang-Ming
Published: June 2015

While most temperate plants probably underwent glacial constriction to refugia and interglacial expansion, another type of interglacial refugia might have existed to maintain alpine plants during warm periods. To test this hypothesis, we applied phylogeographic methods to 763 individuals (62 populations) which belong to 7 taxonomically difficult species of the Rosa sericea complex distributed in alpine regions of the temperate and subtropical zones in eastern Asia. We used three chloroplast (cp) DNA fragments (trnL-trnF, ndhF-rpl32 and ndhJ-trnF) approximately 3,100 bp and nuclear microsatellite (nSSR) on eight sites to determine whether cold tolerant plants experienced expansion during the Pleistocene. The neutral test and mismatch distribution analysis (MDA) indicated that whole populations and major lineages of the Qinghai-Tibet Plateau (QTP) underwent expansion during the middle to late Pleistocene. Environmental niche modeling (ENM) indicates more suitable habitats during the Last Glacial Maximum (LGM) than at present. We concluded that the demographic history of R. sericea, which diverged in the middle Pleistocene, was mostly affected by climatic oscillations instead of by geographical barriers. The low genetic divergence, as well as the weak phylogenetic structure in the R. sericea complex both support treating this complex as a single taxon.
A novel embryonic plasticity gene signature that predicts metastatic competence and clinical outcome
Authors: Soundararajan Rama , Paranjape Anurag N. , Barsan Valentin , Chang Jeffrey T. , Mani Sendurai A.
Published: June 2015

Currently, very few prognosticators accurately predict metastasis in cancer patients. In order to complete the metastatic cascade and successfully colonize distant sites, carcinoma cells undergo dynamic epithelial-mesenchymal-transition (EMT) and its reversal, mesenchymal-epithelial-transition (MET). While EMT-centric signatures correlate with response to therapy, they are unable to predict metastatic outcome. One reason is due to the wide range of transient phenotypes required for a tumor cell to disseminate and recreate a similar histology at distant sites. Since such dynamic cellular processes are also seen during embryo development (epithelial-like epiblast cells undergo transient EMT to generate the mesoderm, which eventually redifferentiates into epithelial tissues by MET), we sought to utilize this unique and highly conserved property of cellular plasticity to predict metastasis. Here we present the identification of a novel prognostic gene expression signature derived from mouse embryonic day 6.5 that is representative of extensive cellular plasticity and predicts metastatic competence in human breast tumor cells. This signature may thus complement conventional clinical parameters to offer accurate prediction for outcome among multiple classes of breast cancer patients.
Signaling through alternative Integrated Stress Response pathways compensates for GCN2 loss in a mouse model of soft tissue sarcoma
Authors: Lehman Stacey L. , Ryeom Sandra , Koumenis Constantinos
Published: June 2015

The tumor microenvironment is characterized by deficiencies in oxygen and nutrients, such as glucose and amino acids. Activation of the GCN2 arm of the Integrated Stress Response (ISR) in response to amino acid deprivation is one mechanism by which tumor cells cope with nutrient stress. GCN2 phosphorylates the alpha subunit of the eukaryotic translation initiation factor eIF2, leading to global downregulation of translation to conserve amino acids and initiation of a transcriptional program through ATF4 to promote recovery from nutrient deprivation. Loss of GCN2 results in decreased tumor cell survival in vitro under amino acid deprivation and attenuated tumor growth in xenograft tumor models. However, it is not known what effects GCN2 loss has on the growth of autochthonous tumors that arise in their native microenvironment. Here, we demonstrate in a genetically engineered mouse model of soft tissue sarcoma that loss of GCN2 has no effect on tumor growth or animal survival. The sarcomas displayed compensatory activation of PERK or phospho-eIF2α independent upregulation of ATF4 in order to maintain ISR signaling, indicating that this pathway is critical for tumorigenesis. These results have important implications for the development and testing of small molecule inhibitors of ISR kinases as cancer therapeutics.
Major depressive disorder and current psychological distress moderate the effect of polygenic risk for obesity on body mass index
Authors: Clarke T-K , Hall L S , Fernandez-Pujals A M , MacIntyre D J , Thomson P , Hayward C , Smith B H , Padmanabhan S , Hocking L J , Deary I J , Porteous D J , McIntosh A M
Published: June 2015

Major depressive disorder (MDD) and obesity are frequently co-morbid and this correlation is partly due to genetic factors. Although specific genetic risk variants are associated with body mass index (BMI) and with larger effect sizes in depressed individuals, the genetic overlap and interaction with depression has not been addressed using whole-genome data. Polygenic profile scores for MDD and BMI were created in 13 921 members of Generation Scotland: the Scottish Family Health Study and tested for their association with BMI, MDD, neuroticism and scores on the General Health Questionnaire (GHQ) (current psychological distress). The association between BMI polygenic profile scores and BMI was tested fitting GHQ, neuroticism or MDD status as an interaction term to test for a moderating effect of mood disorder. BMI polygenic profile scores were not associated with lifetime MDD status or neuroticism although a significant positive association with GHQ scores was found (P=0.0001, β=0.034, r2=0.001). Polygenic risk for MDD was not associated with BMI. A significant interaction between BMI polygenic profile scores and MDD (P=0.0003, β=0.064), GHQ (P=0.0005, β=0.027) and neuroticism (P=0.003, β=0.023) was found when BMI was the dependent variable. The effect of BMI-increasing alleles was greater in those with MDD, high neuroticism or current psychological distress. MDD, neuroticism and current psychological distress amplify the effect of BMI polygenic profile scores on BMI. Depressed individuals with a greater polygenic load for obesity are at greater risk of becoming obese than control individuals.
Cluster–π electronic interaction in a superatomic Au13 cluster bearing σ-bonded acetylide ligands
Authors: Sugiuchi Mizuho , Shichibu Yukatsu , Nakanishi Takayuki , Hasegawa Yasuchika , Konishi Katsuaki
Published: June 2015

Electronic coupling between a Au13 superatom and CC π-units was experimentally evidenced by the absorption spectrum. The existence of such a cluster–π electronic interaction was supported by theoretical calculations.
Gold-catalyzed formal [4π+2π]-cycloadditions of tert-butyl propiolates with aldehydes and ketones to form 4H-1,3-dioxine derivatives
Authors: Karad Somnath Narayan , Chung Wei-Kang , Liu Rai-Shung
Published: June 2015

Novel gold-catalyzed [4π+2π]-cycloadditions of tert-butyl propiolates with aldehydes and ketones have been developed to form 4H-1,3-dioxine derivatives.
Near infrared-caged d-amino acids multifunctional assembly for simultaneously eradicating biofilms and bacteria
Authors: Wei Weili , Bing Wei , Ren Jinsong , Qu Xiaogang
Published: June 2015

Upconversion was used for simultaneous biofilm disassembly and bacteria killing.
Regulating silver morphology via electrochemical reaction
Authors: Liu Wei , Yang Tao , Li Chengxiang , Che Ping , Han Yongsheng
Published: June 2015

By regulating current densities over two orders of magnitude, silver morphologies change from polyhedra to dendrites in electrochemical synthesis.
Vibronic energy relaxation approach highlighting deactivation pathways in carotenoids
Authors: Balevičius Vytautas , Pour Arpa Galestian , Savolainen Janne , Lincoln Craig N. , Lukeš Vladimír , Riedle Eberhard , Valkunas Leonas , Abramavicius Darius , Hauer Jürgen
Published: June 2015

Energy relaxation between two electronic states of a molecule is mediated by a set of relevant vibrational states.
Hydrothermal stability investigation of micro- and mesoporous silica containing long-range ordered cobalt oxide clusters by XAS
Authors: Liu Liang , Wang David K. , Kappen Peter , Martens Dana L. , Smart Simon , Diniz da Costa João C.
Published: June 2015

Cobalt oxide clusters of long range order greatly improved the stability of microporous silica under harsh hydrothermal conditions.
Position and orientational preferences of drug-like compounds in lipid membranes: a computational and NMR approach
Authors: Ma Jerome , Domicevica Laura , Schnell Jason R. , Biggin Philip C.
Published: June 2015

Combining MD simulation with NMR to give a picture of drug–membrane interaction.
Which charge definition for describing the crystal polarizing field and the χ(1) and χ(2) of organic crystals?
Authors: Seidler Tomasz , Champagne Benoît
Published: June 2015

Crystal optical susceptibilities are probes to assess the performance of the charge definition employed to describe the crystal polarizing field.
A detailed study of cholinium chloride and levulinic acid deep eutectic solvent system for CO2capture via experimental and molecular simulation approaches
Authors: Ullah Ruh , Atilhan Mert , Anaya Baraa , Khraisheh Majeda , García Gregorio , ElKhattat Ahmed , Tariq Mohammad , Aparicio Santiago
Published: June 2015

Choline chloride + levulinic acid deep eutectic solvent is studied as a suitable material for CO2capturing purposes.
New opportunities for agricultural digestate valorization: current situation and perspectives
Authors: Monlau F. , Sambusiti C. , Ficara E. , Aboulkas A. , Barakat A. , Carrère H.
Published: June 2015

In the agricultural sector of many European countries, biogas production through anaerobic digestion (AD) is becoming a very fast-growing market necessitating to find novel valorizations routes for digestate.
Anti-allergic and anti-inflammatory properties of Zizyphus mauritiana root bark
Authors: Talmale Suhas , Bhujade Arti , Patil Mandakini
Published: June 2015

The MAF, a fraction with potent anti-allergic and anti-inflammatory compounds, is isolated fromZizyphus mauritianaroot bark. The MAF has an excellent ability to inhibit the complement system, COX-1, COX-2 and 5-LOX and has the potential to prevent anaphylactic shock and the Arthus reaction.
Anti-inflammatory activity of polyphenolics from açai (Euterpe oleracea Martius) in intestinal myofibroblasts CCD-18Co cells
Authors: Dias Manoela Maciel dos Santos , Martino Hércia Stampini Duarte , Noratto Giuliana , Roque-Andrade Andrea , Stringheta Paulo César , Talcott Stephen , Ramos Afonso Mota , Mertens-Talcott Susanne U.
Published: June 2015

This is the first time that the anti-inflammatory activities of açai polyphenols relevant to intestinal inflammation were demonstrated in colon fibroblasts cells.
Carboxymethyl cellulose-templated synthesis of hierarchically structured metal oxides
Authors: Ko Jong Wan , Lee Byung Il , Chung You Jung , Park Chan Beum
Published: June 2015

Cellulose-templated synthesis: Porous metal oxides were successfully synthesized through a simple and environmentally friendly process using carboxymethyl cellulose (CMC) fibers as a sacrificial template.
Enhanced solar light-driven photocatalytic activity of BiOBr–ZnO heterojunctions with effective separation and transfer properties of photo-generated chargers
Authors: Yi Shasha , Zhao Fei , Yue Xinzheng , Wang Dejun , Lin Yanhong
Published: June 2015

The high-efficiency separation of photo-generated charges resulted in a catalyst with excellent photocatalytic activity.
Synthesis and characterisation of novel aluminium and gallium precursors for chemical vapour deposition
Authors: Knapp Caroline E. , Marchand Peter , Dyer Caragh , Parkin Ivan P. , Carmalt Claire J.
Published: June 2015

Synthesis of novel β-ketoiminate compounds (aluminium and gallium) which have been used for the first time as precursors in (AACVD).
Superalkali-hydroxides as strong bases and superbases
Authors: Srivastava Ambrish Kumar , Misra Neeraj
Published: June 2015

The gas-phase basicity values of superalkali hydroxides are closely related to the ionization potentials of the superalkalies and their HOMO–LUMO gaps.
Copper-mediated cyanation of indoles and electron-rich arenes using DMF as a single surrogate
Authors: Zhang Lianpeng , Lu Ping , Wang Yanguang
Published: June 2015

The copper-mediated cyanation of indoles with DMF as a single surrogate of “CN” has been realized.
Theoretical studies on the photoisomerization mechanism of osmium(ii) sulfoxide complexes
Authors: Li Huifang , Zhang Lisheng , Wang Yanfei , Fan Xiaolin
Published: June 2015

Role of 3LF state in the photoisomerization mechanism of photochromic osmium sulfoxide complex, [Os(bpy)2(DMSO)2]2+, is examined theoretically.
Reactive oxygen species: friend or foe?
Authors: Sharma Arun Kumar , Taneja Gourav , Khanna Deepa , Rajput Satyendra K.
Published: June 2015

It is a need to define the line between pathological and physiological functions of reactive oxygen species (ROS) in order to understand their beneficial role over their injurious consequences.
Hole-transport-material-free perovskite solar cells based on nanoporous gold back electrode
Authors: Zhou Xiaoxin , Bao Chunxiong , Li Faming , Gao Hao , Yu Tao , Yang Jie , Zhu Weidong , Zou Zhigang
Published: June 2015

Easily fabricated, directly transferred thin nanoporous gold was first used as back electrode for hole-conduct-material-free perovskite solar cells.
In situ monitoring of total polyphenols content during tea extract oxidation using a portable spectroscopy system with variables selection algorithms
Authors: Pan Wenxiu , Zhao Jiewen , Chen Quansheng , Yuan Lianjun
Published: June 2015

In this work, anin situmonitoring installation for tea extract oxidation including an oxidation system and a spectroscopy system was developed.
Curvature capillary migration of microspheres
Authors: Sharifi-Mood Nima , Liu Iris B. , Stebe Kathleen J.
Published: June 2015

A microsphere migrates by capillarity on a curved fluid interface only if its contact line is pinned.
Adsorption of CO2 on a micro-/mesoporous polyimine modified with tris(2-aminoethyl)amine
Authors: Xu Chao , Bacsik Zoltán , Hedin Niklas
Published: June 2015

Tris(2-aminoethyl)amine modified micro-/mesoporous polyimine shows high CO2 uptakes at low partial pressures and high estimated CO2-over-N2 selectivity up to 1040.
Flux growth of hexagonal cylindrical LiCoO2crystals surrounded by Li-ion conducting preferential facets and their electrochemical properties studied by single-particle measurements
Authors: Zettsu N. , Nishikawa K. , Yubuta K. , Sakurai K. , Yamamoto Y. , Mizuno Y. , Oishi S. , Teshima K.
Published: June 2015

Hexagonal cylindrical LiCoO2crystals surrounded by large {104} planes prepared through template-mediated flux growth exhibit fast Li+transfer and favorable electrochemical performance at high current rates.
Nanostructured terbium-doped ceria spheres: effect of dopants on their physical and chemical properties under reducing and oxidizing conditions
Authors: Acuña L. M. , Muñoz F. F. , Albornoz C. A. , Leyva A. G. , Baker R. T. , Fuentes R. O.
Published: June 2015

The effect of Tb content and synthesis method on the physicochemical properties of nanostructured Tb-doped ceria spheres was studied. The nanostructured spheres contained more Tb as Tb3+than conventionally prepared nanopowders.
Conjugated microporous polymer nanoparticles with enhanced dispersibility and water compatibility for photocatalytic applications
Authors: Ma Beatriz Chiyin , Ghasimi Saman , Landfester Katharina , Vilela Filipe , Zhang Kai A. I.
Published: June 2015

Conjugated microporous polymer nanoparticles as highly dispersible heterogeneous organic photocatalysts for photocatalytic applications.
Facile synthesis of MnO2/carbon nanotubes decorated with a nanocomposite of Pt nanoparticles as a new platform for the electrochemical detection of catechin in red wine and green tea samples
Authors: Ezhil Vilian A. T. , Madhu Rajesh , Chen Shen-Ming , Veeramani Vediyappan , Sivakumar Mani , Huh Yun Suk , Han Young-Kyu
Published: June 2015

Schematic representation of the preparation of the Pt/MnO2/f-MWCNT film for sensing catechin in green tea and red wine samples.
Reduced graphene oxide gated mesoporous silica nanoparticles as a versatile chemo-photothermal therapy system through pH controllable release
Authors: Wang Ting Ting , Lan Jing , Zhang Yue , Wu Zhu Lian , Li Chun Mei , Wang Jian , Huang Cheng Zhi
Published: June 2015

A multifunctional drug delivery system involving coupling photothermal therapy and chemotherapy together was developed, which based on the combination of rGO and MSNs, wherein the cargo molecules could be released in acidic environments due to the cleavage of the CN bond of Schiff bases.
Speech-Language Dissociations, Distractibility, and Childhood Stuttering
Authors: Clark Chagit E. , Conture Edward G. , Walden Tedra A. , Lambert Warren E.
Published: June 2015

Purpose

This study investigated the relation among speech-language dissociations, attentional distractibility, and childhood stuttering.

Method

Participants were 82 preschool-age children who stutter (CWS) and 120 who do not stutter (CWNS). Correlation-based statistics (Bates, Appelbaum, Salcedo, Saygin, & Pizzamiglio, 2003) identified dissociations across 5 norm-based speech-language subtests. The Behavioral Style Questionnaire Distractibility subscale measured attentional distractibility. Analyses addressed (a) between-groups differences in the number of children exhibiting speech-language dissociations; (b) between-groups distractibility differences; (c) the relation between distractibility and speech-language dissociations; and (d) whether interactions between distractibility and dissociations predicted the frequency of total, stuttered, and nonstuttered disfluencies.

Results

More preschool-age CWS exhibited speech-language dissociations compared with CWNS, and more boys exhibited dissociations compared with girls. In addition, male CWS were less distractible than female CWS and female CWNS. For CWS, but not CWNS, less distractibility (i.e., greater attention) was associated with more speech-language dissociations. Last, interactions between distractibility and dissociations did not predict speech disfluencies in CWS or CWNS.

Conclusions

The present findings suggest that for preschool-age CWS, attentional processes are associated with speech-language dissociations. Future investigations are warranted to better understand the directionality of effect of this association (e.g., inefficient attentional processes → speech-language dissociations vs. inefficient attentional processes ← speech-language dissociations).
Ossification of the Posterior Longitudinal Ligament: Etiology, Diagnosis, and Outcomes of Nonoperative and Operative Management
Authors: Abiola Rasheed , Rubery Paul , Mesfin Addisu
Published: June 2015

Study Design

Narrative review.

Objective

To provide an overview on the diagnosis, natural history, and nonoperative and operative management of ossification of the posterior longitudinal ligament (OPLL). OPLL is a multifactorial condition caused by ectopic hyperostosis and calcification of the posterior longitudinal ligament. Familial inheritance and genetic factors have been implicated in the etiology of OPLL. The cervical spine is most commonly affected followed by the thoracic spine. The clinical manifestations range from asymptomatic to myelopathy or myeloradiculopathy.

Methods

Using PubMed, studies published prior to October 2014 with the keywords “OPLL, etiology”; “OPLL, genetics”; “OPLL, spinal cord injury”; “OPLL, natural history”; “OPLL, non-surgical management”; OPLL, surgical management”; “OPLL, surgical complications” were evaluated.

Results

The review addresses the etiology, epidemiology, classification, clinical presentation, imaging findings, and nonoperative and operative management of OPLL. Complications associated with surgical management of OPLL are also discussed.

Conclusions

OPLL commonly presents with myelopathy and radiculopathy. Spine providers should consider OPLL in their differential diagnosis and when reviewing images. If surgical intervention is pursued, imaging-based measurements and findings can help in choosing an anterior versus posterior surgical approach.
A catalytic oligomeric motor that walks along a filament track
Authors: Huang Mu-Jie , Kapral Raymond
Published: June 2015

Most biological motors in the cell execute chemically powered conformational changes as they walk on biopolymer filaments in order to carry out directed transport functions. Synthetic motors that operate in a similar manner are being studied since they have the potential to perform similar tasks in a variety of applications. In this paper, a synthetic nanomotor that moves along a filament track, without invoking motor conformational changes, is constructed and its properties are studied in detail. The motor is an oligomer comprising three linked beads with specific binding properties. The filament track is a stiff polymer chain, also described by a linear chain of linked coarse-grained molecular groups modeled as beads. Reactions on the filament that are catalyzed by a motor bead and use fuel in the environment, in conjunction within the binding affinities of the motor beads to the filament beads, lead to directed motion. The system operates out of equilibrium due to the state of the filament and supply of fuel. The motor, filament, and surrounding medium are all described at microscopic level that permits a full analysis of the motor motion. A stochastic model that captures the main trends seen in the simulations is also presented. The results of this study point to some of the key features that could be used to construct nanomotors that undergo biased walks powered by chemical reactions on filaments.
A numerically efficient damping model for acoustic resonances in microfluidic cavities
Authors: Hahn P. , Dual J.
Published: June 2015

Bulk acoustic wave devices are typically operated in a resonant state to achieve enhanced acoustic amplitudes and high acoustofluidic forces for the manipulation of microparticles. Among other loss mechanisms related to the structural parts of acoustofluidic devices, damping in the fluidic cavity is a crucial factor that limits the attainable acoustic amplitudes. In the analytical part of this study, we quantify all relevant loss mechanisms related to the fluid inside acoustofluidic micro-devices. Subsequently, a numerical analysis of the time-harmonic visco-acoustic and thermo-visco-acoustic equations is carried out to verify the analytical results for 2D and 3D examples. The damping results are fitted into the framework of classical linear acoustics to set up a numerically efficient device model. For this purpose, all damping effects are combined into an acoustofluidic loss factor. Since some components of the acoustofluidic loss factor depend on the acoustic mode shape in the fluid cavity, we propose a two-step simulation procedure. In the first step, the loss factors are deduced from the simulated mode shape. Subsequently, a second simulation is invoked, taking all losses into account. Owing to its computational efficiency, the presented numerical device model is of great relevance for the simulation of acoustofluidic particle manipulation by means of acoustic radiation forces or acoustic streaming. For the first time, accurate 3D simulations of realistic micro-devices for the quantitative prediction of pressure amplitudes and the related acoustofluidic forces become feasible.
Ten new predicted covalent organic frameworks with strong optical response in the visible and near infrared
Authors: Yang Li-Ming , Dornfeld Matthew , Hui Pik-Mai , Frauenheim Thomas , Ganz Eric
Published: June 2015

We use density functional theory to predict and evaluate 10 novel covalent organic frameworks (COFs), labeled (X4Y)(BDC)3, (X = C/Si; Y = C, Si, Ge, Sn, and Pb), with topology based on metal organic framework isoreticular metal-organic framework (IRMOF-1), but with new elements substituted for the corner atoms. We show that these new materials are stable structures using frequency calculations. For two structures, (C4C and Si4C) molecular dynamics simulations were performed to demonstrate stability of the systems up to 600 K for 10 ps. This demonstrates the remarkable stability of these systems, some of which may be experimentally accessible. For the C4C material, we also explored the stability of isolated corners and linkers and vacuum and started to build the structure from these pieces. We discuss the equilibrium lattice parameters, formation enthalpies, electronic structures, chemical bonding, and mechanical and optical properties. The predicted bulk moduli of these COFs range from 18.9 to 23.9 GPa, larger than that of IRMOF-1 (ca. 15.4 GPa), and larger than many existing 3D COF materials. The band gaps range from 1.5 to 2.1 eV, corresponding to 600–830 nm wavelength (orange through near infrared). The negative values of the formation enthalpy suggest that they are stable and should be experimentally accessible under suitable conditions. Seven materials distort the crystal structure to a lower space group symmetry Fm-3, while three materials maintain the original Fm-3m space group symmetry. All of the new materials are highly luminescent. We hope that this work will inspire efforts for experimental synthesis of these new materials.
Delineation of degradation patterns of C60-based organic solar cells under different environments
Authors: Ciammaruchi Laura , Wang Chenggong , Gao Yongli , Tang Ching W.
Published: June 2015

The photovoltaic (PV) parameters of a planar heterojunction solar cell with 1,1-bis-(4-bis(4-methyl- phenyl)-amino-phenyl)-cyclohexane as small molecular donor (D) and C60 as archetypical acceptor (A) have been analyzed, after exposure of the photoactive layer (PAL) to different gaseous ambiences such as N2, O2, H2O, and air. We find that for the same exposure time, even minor O2 amounts lead to more detrimental results compared to H2O exposure. For devices stressed closer to the D/A interface, we argue that the photo-conversion efficiency (PCE) decreases due to creation of recombination centers at the interface, which induce exciton diffusion and charge generation losses. For devices stressed further from it, traps at the outer C60 layer affect the free carrier transport efficiency. We also show the relationship between the degradation of PV parameters and C60 conductivity loss. We find a direct connection between gas pressure and PCE loss. In-situ XPS measurements of gas-exposed PALs are in agreement with the results obtained through electrical measurements.
Charge transition levels of oxygen, lanthanum, and fluorine related defect structures in bulk hafnium dioxide (HfO2): An ab initio investigation
Authors: Leitsmann Roman , Lazarevic Florian , Nadimi Ebrahim , Öttking Rolf , Plänitz Philipp , Erben Elke
Published: June 2015

Intrinsic defect structures and impurity atoms are one of the main sources of leakage current in metal-oxide-semiconductor devices. Using state of the art density functional theory, we have investigated oxygen, lanthanum, and fluorine related defect structures and possible combinations of them. In particular, we have calculated their charge transition levels in bulk m-HfO2. For this purpose, we have developed a new scaling scheme to account for the band gap underestimation within the density functional theory. The obtained results are able to explain the recent experimental observation of a reduction of the trap density near the silicon valence band edge after NF3 treatment and the associated reduction of the device degradation.
Appearance of large crystalline domains in VO2 films grown on sapphire (001) and their phase transition characteristics
Authors: Azhan Nurul Hanis , Su Kui , Okimura Kunio , Zaghrioui Mustapha , Sakai Joe
Published: June 2015

We report the first observation of large crystalline domains of several μm-size in VO2 films deposited on Al2O3 (001) substrates by rf-biased reactive sputtering technique. The large crystalline domains, dominated with random in-plane oriented growth of (011)M1-orientation, appear only under adequate substrate biasing, such as 10 W, while most biasing conditions result in conventional nanosized grains of highly oriented (010)M1-orientation. Two temperature-controlled analyses, x-ray diffraction and micro-Raman spectroscopy, have revealed that some parts of large crystalline domains undergo intermediate monoclinic (M2) phase during the thermally-induced structural phase transition from monoclinic (M1) to rutile-tetragonal (R) phase. As an effect of the appearance of large crystalline domains, the film showed in-plane tensile stress, resulting in high TIMT of 69 °C due to the elongation of the V-V distance in its low-temperature monoclinic phase.
I-V characteristics of in-plane and out-of-plane strained edge-hydrogenated armchair graphene nanoribbons
Authors: Cartamil-Bueno S. J. , Rodríguez-Bolívar S.
Published: June 2015

The effects of tensile strain on the current-voltage (I-V) characteristics of hydrogenated-edge armchair graphene nanoribbons are investigated by using DFT theory. The strain is introduced in two different ways related to the two types of systems studied in this work: in-plane strained systems (A) and out-of-plane strained systems due to bending (B). These two kinds of strain lead to make a distinction among three cases: in-plane strained systems with strained electrodes (A1) and with unstrained electrodes (A2), and out-of-plane homogeneously strained systems with unstrained, fixed electrodes (B). The systematic simulations to calculate the electronic transmission between two electrodes were focused on systems of 8 and 11 dimers in width. The results show that the differences between cases A2 and B are negligible, even though the strain mechanisms are different: in the plane case, the strain is uniaxial along its length; while in the bent case, the strain is caused by the arc deformation. Based on the study, a new type of nanoelectromechanical system solid state switching device is proposed.
Phase field modelling of strain induced crystal growth in an elastic matrix
Authors: Laghmach Rabia , Candau Nicolas , Chazeau Laurent , Munch Etienne , Biben Thierry
Published: June 2015

When a crystal phase grows in an amorphous matrix, such as a crystallisable elastomer, containing cross-links and/or entanglements, these “topological constraints” need to be pushed away from the crystal phase to allow further crystallization. The accumulation of these topological constraints in the vicinity of the crystal interface may store elastic energy and affect the phase transition. To evaluate the consequences of such mechanism, we introduce a phase field model based on the Flory theory of entropic elasticity. We show that the growth process is indeed sensibly affected, in particular, an exponential increase of the surface energy with the displacement of the interface is induced. This explains the formation of stable nano-crystallites as it is observed in the Strain Induced Crystallization (SIC) of natural rubber. Although simple, the model developed here is able to account for many interesting features of SIC, for instance, the crystallite shapes and their sizes which depend on the applied deformation.
Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study
Authors: Zhao Shu-Xia , Zhang Yu-Ru , Gao Fei , Wang You-Nian , Bogaerts Annemie
Published: June 2015

A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.
Photoresponsive microvalve for remote actuation and flow control in microfluidic devices
Authors: Jadhav Amol D. , Yan Bao , Luo Rong-Cong , Wei Li , Zhen Xu , Chen Chia-Hung , Shi Peng
Published: June 2015

Microvalves with different actuation methods offer great integrability and flexibility in operation of lab-on-chip devices. In this work, we demonstrate a hydrogel-based and optically controlled modular microvalve that can be easily integrated within a microfluidic device and actuated by an off-chip laser source. The microvalve is based on in-channel trapping of microgel particles, which are composed of poly(N-isopropylacrylamide) and polypyrrole nanoparticles. Upon irradiation by a near-infrared (NIR) laser, the microgel undergoes volumetric change and enables precisely localized fluid on/off switching. The response rate and the “open” duration of the microvalve can be simply controlled by adjusting the laser power and exposure time. We showed that the trapped microgel can be triggered to shrink sufficiently to open a channel within as low as ∼1–2 s; while the microgel swells to re-seal the channel within ∼6–8 s. This is so far one of the fastest optically controlled and hydrogel-based microvalves, thus permitting speedy fluidic switching applications. In this study, we successfully employed this technique to control fluidic interface between laminar flow streams within a Y-junction device. The optically triggered microvalve permits flexible and remote fluidic handling, and enables pulsatile in situ chemical treatment to cell culture in an automatic and programmed manner, which is exemplified by studies of chemotherapeutic drug induced cell apoptosis under different drug treatment strategies. We find that cisplatin induced apoptosis is significantly higher in cancer cells treated with a pulsed dose, as compared to continuous flow with a sustained dose. It is expected that our NIR-controlled valving strategy will provide a simple, versatile, and powerful alternative for liquid handling in microfluidic devices.
Self-sustained criterion with photoionization for positive dc corona plasmas between coaxial cylinders
Authors: Zheng Yuesheng , Zhang Bo , He Jinliang
Published: June 2015

The positive dc corona plasmas between coaxial cylinders in air under the application of a self-sustained criterion with photoionization are investigated in this paper. A photon absorption function suitable for cylindrical electrode, which can characterize the total photons within the ionization region, is proposed on the basis of the classic corona onset criteria. Based on the general fluid model with the self-sustained criterion, the role of photoionization in the ionization region is clarified. It is found that the surface electric field keeps constant under a relatively low corona current, while it is slightly weakened with the increase of the corona current. Similar tendencies can be found under different conductor radii and relative air densities. The small change of the surface electric field will become more significant for the electron density distribution as well as the ionization activity under a high corona current, compared with the results under the assumption of a constant surface field. The assumption that the surface electric field remains constant should be corrected with the increase of the corona current when the energetic electrons with a distance from the conductor surface are concerned.
Magneto-optical imaging technique for hostile environments: The ghost imaging approach
Authors: Meda A. , Caprile A. , Avella A. , Ruo Berchera I. , Degiovanni I. P. , Magni A. , Genovese M.
Published: June 2015

In this paper, we develop an approach to magneto optical imaging (MOI), applying a ghost imaging (GI) protocol to perform Faraday microscopy. MOI is of the utmost importance for the investigation of magnetic properties of material samples, through Weiss domains shape, dimension and dynamics analysis. Nevertheless, in some extreme conditions such as cryogenic temperatures or high magnetic field applications, there exists a lack of domain images due to the difficulty in creating an efficient imaging system in such environments. Here, we present an innovative MOI technique that separates the imaging optical path from the one illuminating the object. The technique is based on thermal light GI and exploits correlations between light beams to retrieve the image of magnetic domains. As a proof of principle, the proposed technique is applied to the Faraday magneto-optical observation of the remanence domain structure of an yttrium iron garnet sample.
Orientation dependent fracture behavior of nanotwinned copper
Authors: Kobler Aaron , Hodge Andrea M. , Hahn Horst , Kübel Christian
Published: June 2015

Columnar grown nanotwinned Cu was tensile tested in-situ inside the TEM in combination with automated crystal orientation mapping scanning transmission electron microscopy to investigate the active deformation mechanisms present in this material. Two tensile directions were applied, one parallel to the twin boundaries and the other perpendicular to the twin boundaries. In case of tensile testing perpendicular to the twin boundaries, the material deformed by detwinning and the formation of new grains, whereas in the parallel case, no new grains were formed and the fracture happened along the twin boundaries and a boundary that has formed during the deformation.
Photoluminescence of radiation-induced color centers in lithium fluoride thin films for advanced diagnostics of proton beams
Authors: Piccinini M. , Ambrosini F. , Ampollini A. , Picardi L. , Ronsivalle C. , Bonfigli F. , Libera S. , Nichelatti E. , Vincenti M. A. , Montereali R. M.
Published: June 2015

Systematic irradiation of thermally evaporated 0.8 μm thick polycrystalline lithium fluoride films on glass was performed by proton beams of 3 and 7 MeV energies, produced by a linear accelerator, in a fluence range from 1011 to 1015 protons/cm2. The visible photoluminescence spectra of radiation-induced F2 and F3+ laser active color centers, which possess almost overlapping absorption bands at about 450 nm, were measured under laser pumping at 458 nm. On the basis of simulations of the linear energy transfer with proton penetration depth in LiF, it was possible to obtain the behavior of the measured integrated photoluminescence intensity of proton irradiated LiF films as a function of the deposited dose. The photoluminescence signal is linearly dependent on the deposited dose in the interval from 103 to about 106 Gy, independently from the used proton energies. This behavior is very encouraging for the development of advanced solid state radiation detectors based on optically transparent LiF thin films for proton beam diagnostics and two-dimensional dose mapping.
Highly enhanced and temporally stable field emission from MWCNTs grown on aluminum coated silicon substrate
Authors: Sreekanth M. , Ghosh S. , Patra R. , Srivastava P.
Published: June 2015

In this work, a detailed field emission study of multi-walled carbon nanotubes (MWCNTs) grown on Si and Al coated Si substrates is reported. Morphological and microstructural studies of the films show higher entanglement of CNTs in the case of CNT/Si film as compared to CNT/Al/Si film. Raman studies show that the defect mediated peak (D) is substantially suppressed as compared to graphitic peak (G) resulting in significant reduction in ID/IG value in CNT/Al/Si film. Field emission (FE) current density of CNT/Al/Si film (∼25 mA/cm2) is significantly higher as compared to that of CNT/Si film (∼1.6 mA/cm2). A substantial improvement in temporal stability is also observed in CNT/Al/Si film. This enhancement in field emission current is attributed to strong adhesion between substrate and CNTs, low work function, high local field enhancement factor at the CNT tips and less entanglement of CNTs grown on Al/Si. The temporally stable CNT/Al/Si cold cathode can be a potential candidate to replace conventional electron sources in prototype devices.
Nanocomposite polymer carbon-black coating for triggering pyro-electrohydrodynamic inkjet printing
Authors: Coppola S. , Mecozzi L. , Vespini V. , Battista L. , Grilli S. , Nenna G. , Loffredo F. , Villani F. , Minarini C. , Ferraro P.
Published: June 2015

The pyro-electrohydrodynamic (EHD) manipulation of liquids has been discovered and demonstrated recently as a high resolution printing technique avoiding the use of nozzles and external electrodes. The activation of the pyro-electric effect is usually achieved on ferroelectric crystals by an external heating source or by an infrared laser. Here, we show an original modality for triggering the pyro-EHD process through a light-absorbing polymer nanocomposite thin layer deposited on the ferroelectric substrate, thus overcoming some limitations of the previous configuration. Significant simplification and compactness of the set-up is achieved thanks to the nanocomposite coating, since a commercial low-cost white-light halogen lamp can be adopted to trigger the pyro-jetting process from a liquid reservoir. Remarkably, high resolution is achieved in dispensing very high viscous liquids. Practical demonstrations in polymer optical microlenses direct printing using polydimethylsiloxane and poly(methyl methacrylate) are finally reported to validate the approach in handling high-viscous polymers for practical applications.
Cathodoluminescence study of radiative interface defects in thermally grown SiO2/4H-SiC(0001) structures
Authors: Fukushima Yuta , Chanthaphan Atthawut , Hosoi Takuji , Shimura Takayoshi , Watanabe Heiji
Published: June 2015

Radiative defects in thermally grown SiO2/4H-SiC(0001) structures and their location in depth were investigated by means of cathodoluminescence spectroscopy. It was found that while luminescence peaks ascribed to oxygen vacancy and nonbridging oxygen hole centers were observed both from thermal oxides grown on (0001) Si-face and C-face surfaces as with thermal oxides on Si, intense yellow luminescence at a wavelength of around 600 nm was identified only from the oxide interface on the Si-face substrate regardless of the oxide thickness and dopant type. Possible physical origins of the radiative centers localized near an oxide interface of a few nm thick are discussed on the basis of visible light emission from Si backbone structures.