bluuebunny/crossref_metadata_2025 huggingface dataset:
Peripheral brain-derived neurotrophic factor in autism spectrum disorder: a systematic review and meta-analysis
Authors: Zheng Zhen , Zhang Li , Zhu Tingting , Huang Jichong , Qu Yi , Mu Dezhi
Published: August 2016

Brain-derived neurotrophic factor (BDNF) regulates neuronal survival and growth and promotes synaptic plasticity. Recently, researchers have begun to explore the relationship between peripheral BDNF levels and autism spectrum disorder (ASD), but the findings are inconsistent. We undertook the first systematic review and meta-analysis of studies examining peripheral BDNF levels in ASD compared with healthy controls. The PubMed, Embase, and Cochrane Library databases were searched for studies published before February 2016. Fourteen studies involving 2,707 participants and 1,131 incident cases were included. The meta-analysis provided evidence of higher peripheral BDNF levels in ASD compared with controls [standardized mean difference (SMD) = 0.63, 95% confidence interval (95% CI) = 0.18–1.08; P = 0.006]. Subgroup analyses revealed higher BDNF levels in ASD compared with controls for both serum [SMD = 0.58, 95% CI = 0.11–1.04; P = 0.02] and plasma [SMD = 1.27, 95% CI = 0.92–1.61; P < 0.001]. Studies of childhood yielded similar cumulative effect size [SMD = 0.78, 95% CI = 0.31–1.26; P = 0.001], while this was not true for the studies of adulthood [SMD = 0.04, 95% CI = −1.72–1.80; P = 0.97]. This meta-analysis suggests that peripheral BDNF levels are a potential biomarker of ASD.
Association between angiotensin converting enzyme gene insertion/deletion polymorphism and renal scar risk in children vesicoureteral reflex: a reappraise meta-analysis
Authors: Ai Jin-Wei , Zeng Xian-Tao , Liu Ying , Fu Yu , Liu Tong-Zu , Pei Bin
Published: August 2016

Vesicoureteral reflex(VUR) is a common disease in children. Some studies indicated that the angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism associated with the renal scar in VUR, but not all researchers agreed with it. To clarify the effect of ACE I/D polymorphism on renal scar risk in children with VUR, we performed the present meta-analysis. PubMed, CNKI, CBM, and Embase databases were searched for studies that examined the relationship between ACE I/D polymorphism and renal scar risk in children with VUR. The Stata 12.0 software was used for statistical analyses. 11 case-control studies with 1,032 VUR patients were analyzed. The results showed that the DD genotype and D allele were associated with renal scar risk in overall VUR patients, DD vs. DI + II: OR = 1.61, 95% CI = 1.04–2.49, P = 0.03; DD vs. II: OR = 1.78, 95% CI = 1.20–2.65, P < 0.01; D vs. I: OR = 1.38, 95% CI = 1.02–1.86, P = 0.04. Similar results were revealed in Turks, but not in Caucasians and Asians. Our meta-analysis indicated that the ACE DD genotype may increase the risk of renal scar in children with VUR.
Template-mediated Synthesis of Hollow Microporous Organic Nanorods with Tunable Aspect Ratio
Authors: Li Qingyin , Jin Shangbin , Tan Bien
Published: August 2016

Hollow microporous organic nanorods (HMORs) with hypercrosslinked polymer (HCPs) shells were synthesized through emulsion polymerization followed by hypercrosslinking. The HMORs have tunable aspect ratios, high BET surface areas and monodispersed morphologies, showing good performance in gas adsorpion.
Structural basis of unique ligand specificity of KAI2-like protein from parasitic weed Striga hermonthica
Authors: Xu Yuqun , Miyakawa Takuya , Nakamura Hidemitsu , Nakamura Akira , Imamura Yusaku , Asami Tadao , Tanokura Masaru
Published: August 2016

The perception of two plant germination inducers, karrikins and strigolactones, are mediated by the proteins KAI2 and D14. Recently, KAI2-type proteins from parasitic weeds, which are possibly related to seed germination induced by strigolactone, have been classified into three clades characterized by different responses to karrikin/strigolactone. Here we characterized a karrikin-binding protein in Striga (ShKAI2iB) that belongs to intermediate-evolving KAI2 and provided the structural bases for its karrikin-binding specificity. Binding assays showed that ShKAI2iB bound karrikins but not strigolactone, differing from other KAI2 and D14. The crystal structures of ShKAI2iB and ShKAI2iB-karrikin complex revealed obvious structural differences in a helix located at the entry of its ligand-binding cavity. This results in a smaller closed pocket, which is also the major cause of ShKAI2iB’s specificity of binding karrikin. Our structural study also revealed that a few non-conserved amino acids led to the distinct ligand-binding profile of ShKAI2iB, suggesting that the evolution of KAI2 resulted in its diverse functions.
Inhibition of VEGF165/VEGFR2-dependent signaling by LECT2 suppresses hepatocellular carcinoma angiogenesis
Authors: Chen Chi-Kuan , Yu Wen-Hsuan , Cheng Tsu-Yao , Chen Min-Wei , Su Chia-Yi , Yang Yi-Chieh , Kuo Tsang-Chih , Lin Ming-Tsan , Huang Ya-Chi , Hsiao Michael , Hua Kuo-Tai , Hung Mien-Chie , Kuo Min-Liang
Published: August 2016

Hepatocellular carcinoma (HCC) relies on angiogenesis for growth and metastasis. Leukocyte cell-derived chemotaxin 2 (LECT2) is a cytokine and preferentially expressed in the liver. Previous studies have found that LECT2 targets to both immune and tumor cells to suppress HCC development and vascular invasion. Although LECT2 did not affect HCC cells growth in vitro, it still suppressed HCC xenografts growth in immune-deficient mice, suggesting other cells such as stroma cells may also be targeted by LECT2. Here, we sought to determine the role of LECT2 in tumor angiogenesis in HCC patients. We found that LECT2 expression inhibited tumor growth via angiogenesis in the HCC xenograft model. Specifically, we demonstrated that recombinant human LECT2 protein selectively suppressed vascular endothelial growth factor (VEGF)165-induced endothelial cell proliferation, migration, and tube formation in vitro and in vivo. Mechanistically, LECT2 reduced VEGF receptor 2 tyrosine phosphorylation and its downstream extracellular signal-regulated kinase and AKT phosphorylation. Furthermore, LECT2 gene expression correlated negatively with angiogenesis in HCC patients. Taken together, our findings demonstrate that LECT2 inhibits VEGF165-induced HCC angiogenesis through directly binding to VEGFR2 and has broad applications in treating VEGF-mediated solid tumors.
Plasma enhanced vortex fluidic device manipulation of graphene oxide
Authors: Jones Darryl B. , Chen Xianjue , Sibley Alexander , Quinton Jamie S. , Shearer Cameron J. , Gibson Christopher T. , Raston Colin L.
Published: August 2016

A vortex fluid device (VFD) with non-thermal plasma liquid processing within dynamic thin films has been developed.
Hydrogen evolution in [NiFe] hydrogenases and related biomimetic systems: similarities and differences
Authors: Das Ranjita , Neese Frank , van Gastel Maurice
Published: August 2016

Schematic overview of the orbitals that play a role in the cycle of reversible hydrogen oxidation in [NiFe] hydrogenases.
Prediction of two-photon absorption enhancement in red fluorescent protein chromophores made from non-canonical amino acids
Authors: Salem M. Alaraby , Twelves Isaac , Brown Alex
Published: August 2016

TD-DFT screening of RFP-derived chromophores using B3LYP and CAM-B3LYP highlights a Gold FP-like chromophore with large TPA (two-photon absorption).
Mechanisms for dehydrogenation and hydrogenation of N-heterocycles using PNP-pincer-supported iron catalysts: a density functional study
Authors: Sawatlon Boodsarin , Surawatanawong Panida
Published: August 2016

The bifunctionality of Fe-PNP plays a role in stabilizing the ion-pair complex in the dehydrogenation via a hydrogen bonding and a C–H agostic interaction.
Biomimetic deiodination of thyroid hormones and iodothyronamines – a structure–activity relationship study
Authors: Mondal Santanu , Mugesh Govindasamy
Published: August 2016

Deiodination of thyroid hormones and their decarboxylated metabolites, iodothyronamines by a series ofperi-substituted selenium-containing naphthalene derivatives has been described.
In situ polymerization induced supramolecular hydrogels of chitosan and poly(acrylic acid-acrylamide) with high toughness
Authors: Li Jin , Su Zhilong , Ma Xiaodong , Xu Hongjie , Shi Zixing , Yin Jie , Jiang Xuesong
Published: August 2016

A novel type of supramolecular hydrogel was developed byin situpolymerization of acrylic acid (AA) and acrylamide (AM) monomers in the aqueous solution of chitosan (CS) based on the dynamic electrostatic interaction of ions.
Synthesis, characterization, and crystal structure of RNA targeted l- and d-phenylalanine-(1,10-phen)–copper(ii) conjugate complexes: comparative in vitro RNA binding profile of enantiomers and their biological evaluation by morphological studies and antibacterial activity
Authors: Sharma Surbhi , Toupet Loic , Ahmad Musheer , Arjmand Farukh
Published: August 2016

Chiral Cu(ii) complexes targeting RNA showing morphological changes and Docking model.
A three-dimensional nitrogen-doped graphene aerogel-activated carbon composite catalyst that enables low-cost microfluidic microbial fuel cells with superior performance
Authors: Yang Yang , Liu Tianyu , Liao Qiang , Ye Dingding , Zhu Xun , Li Jun , Zhang Pengqing , Peng Yi , Chen Shaowei , Li Yat
Published: August 2016

Low-cost electrodes were used in miniature microbial fuel cells to generate a remarkably high volumetric power density.
Excellent energy density of polymer nanocomposites containing BaTiO3@Al2O3 nanofibers induced by moderate interfacial area
Authors: Pan Zhongbin , Yao Lingmin , Zhai Jiwei , Shen Bo , Liu Shaohui , Wang Haitao , Liu Jinhua
Published: August 2016

A moderate interfacial area results in significantly enhancement of electric breakdown strength in BaTiO3@Al2O3 nanocomposites. An energy density of ≈12.18 J cm−3 is achieved with a small loading of 5 vol% BaTiO3@Al2O3 nfs.
Tailored mesoporous silica nanosystem with enhanced permeability of the blood–brain barrier to antagonize glioblastoma
Authors: You Yuanyuan , Yang Liye , He Lizhen , Chen Tianfeng
Published: August 2016

Herein, a tailored MSNs nanosystem modified by an RGD peptide has been rationally designed, synthesized and used as a carrier of anticancer agents to enhance its BBB permeability and anticancer efficacy to treat human brain glioma.
KF‐based technique for detection of anomalous condition of the PV panels
Authors: Ghanbari Teymoor , Khayam Hoseini Seyed Reza
Published: August 2016

This study deals with an approach for photovoltaic (PV) panel monitoring based on extended Kalman filter (EKF). For detection of anomalous condition, I–V and P–V characteristics derived by the PV model in normal condition (named reference model) are compared with the corresponding ones extracted from the PV model in the test condition (named test model). Parameters of the reference model are obtained from the standard test condition. Generally, maximum power point (MPP) tracking algorithms deviate operating point of PV systems to find the global MPP. In the proposed approach, the measured operating points of the PV system are passed through the EKF. In fact, the EKF is an adaptive low‐pass filter for estimation of the operating MPP dictated by the MPP tracker. During a predefined inspection time interval, parameters of the test model are derived from the estimated MPP. The performance of the proposed method is evaluated using some simulations and experiments in different normal and anomalous conditions. The results confirm desirable accuracy and reliability of the proposed method for detection of the PV panels’ anomalous condition.
Agent‐based decentralised load flow computation for smart management of distribution system
Authors: Saxena Kritika , Abhyankar Abhijit R.
Published: August 2016

Centralised operation of distribution system suffer from inherent difficulties like increased complexities with increased system size, consequent frequent upgradation, delayed decision making and so on. Paradigm shift towards decentralised operations overcomes the aforesaid problems and assist in automated grid operations. Load flow is an indispensable tool, where the system operator does centralised calculation of state variables. This study proposes a novel approach towards decentralised load flow computation for weakly meshed distribution system. Agent technology is employed to design the framework which is based on agent relaying concept. The agents are located on system buses, and have limited access to information pertaining to system topology and nodal injections. By coordinating with neighbouring agents, they aim towards the fulfilment of their own goal, i.e. bus voltage calculation. To achieve this, several behaviours such as forward sweep, backward sweep, break point calculations and scenario generation are incorporated in the proposed system design. The solution thus obtained is decentralised in nature. The agent designing is done under JAVA environment on JADE platform. Two case studies considering 15 bus and 69 bus radial distribution systems are simulated with the proposed concept to show the validity and applicability of the proposed framework for smart grid management systems.
Decoupled control strategy for the operation of capacitor‐excited induction generator for DC power applications
Authors: Mahajan Sumedha M. , Senthil Kumar Subramanium , Kumaresan Natarajan , Ammasai Gounden Nanjappa Gounder , Rajkumar Eanaganti
Published: August 2016

In this study, voltage oriented decoupled current mode control technique has been proposed for the operation of the capacitor‐excited induction generator with pulse‐width modulation (PWM) rectifier systems for supplying isolated DC loads. The proposed controller maintains constant voltage at the DC load terminals and also maintains unity power factor with very less harmonics at the PWM rectifier input terminals. The configuration and implementation of the control scheme employing dSPACE 1103 real‐time controller have been fully described. A method for predetermining the steady‐state performance of the proposed system has been developed and described with relevant analytical expressions. The effective load at the generator terminals becomes only resistance, since unity power factor is maintained at the PWM rectifier input terminals by the closed‐loop controller. To verify the successful working of the proposed control strategy during transient conditions, the proposed system has been modelled in the MATLAB/Simulink toolbox and results are presented. A prototype system consisting of CEIG, PWM rectifier and the associated control circuits has been built in the laboratory for experimental verification. A close agreement between the experimental results and predicted values confirms the validity of the analysis and successful working of the proposed control strategy.
Robust joint estimation for time delay and Doppler frequency shift based on generalised sigmoid cyclic cross‐ambiguity function
Authors: Ling Yu , TianShuang Qiu , ShengYang Luan
Published: August 2016

In this study, a novel concept, i.e. the tuneable sigmoid cyclic correlation, is proposed, and a relative estimator, named the generalised sigmoid cyclic cross‐ambiguity function, is also derived to deal with impulsive noise and co‐channel interference. Based on these concepts, a robust joint estimation method for time delay and Doppler frequency shift is proposed as well. Both theoretical analysis and simulations demonstrate the superior performances of the proposed approach over other existing methods, especially under strong impulsive noise.
Methotrexat bei atypischer nicht arteriitischer anteriorer ischämischer Optikusneuropathie
Authors: Lenk J. , Hermann C. , Matthé E. , Pillunat L. , Sandner D.
Published: August 2016

Hintergrund: Erkrankungen des N. opticus können multiple Ursachen haben, so spielen im klinischen Alltag vor allem vaskuläre, entzündliche und toxische Prozesse eine Rolle. Diese Erkrankungen sind meist von einer progredienten Verschlechterung in der statischen Perimetrie und Visusabfall begleitet. Allerdings ist es oft schwierig, eine eindeutige Ursache zu eruieren.

Methoden: Wir stellen eine 74-jährige Patientin vor, die sich bei uns mit progredienten Gesichtsfeldausfällen und Papillenschwellung am linken Auge vorstellte und unter der Verdachtsdiagnose nicht arteriitische anteriore ischämische Optikusneuropathie (NAION) behandelt wurde. Unter Prednisolon kam es zunächst zu einer Befundbesserung. Nach Ausschleichen der Therapie trat untypischerweise unmittelbar ein neuer Krankheitsschub auf. Die Patientin wies bis auf eine Mikropapille und eine arterielle Hypotonie keinen der typischen Risikofaktoren für eine NAION auf. Es wurde eine Therapie mit 10 mg Methotrexat (MTX) 1×/Woche begonnen. Der Krankheitsverlauf wurde über 2 Jahre kontrolliert.

Ergebnisse: Unter nachfolgend eingeleiteter MTX-Therapie waren diese Defekte regredient mit Rückgang der Papillenschwellung. Im Verlauf zeigte sich Befundstabilität unter 15 mg 1×/Woche MTX, auch nach komplettem Ausschleichen von Prednisolon. Eine Optikusatrophie, oft infolge einer abgelaufenen anterioren ischämischen Optikusneuropathie (AION) vorhanden, trat nicht auf, was den Verdacht auf eine zusätzliche autoimmunologische Genese bestärkt. Nebenwirkungen unter MTX wurden nicht dokumentiert.

Schlussfolgerung: Im Zweifel kann bei atypischen Krankheitsverläufen ein zusätzliches autoimmunologisches Geschehen vermutet werden und eine Immunsuppression mit MTX sinnvoll sein, da Prednisolon zwar den Krankheitsschub günstig beeinflusst, aber aufgrund seines Nebenwirkungsprofils nicht dauerhaft in einer Dosis oberhalb der Cushing-Schwelle gegeben werden kann.
Precise control of polymer coated nanopores by nanoparticle additives: Insights from computational modeling
Authors: Eskandari Nasrabad Afshin , Jasnow David , Zilman Anton , Coalson Rob D.
Published: August 2016

Polymer-nanoparticle composites are a promising new class of materials for creation of controllable nano-patterned surfaces and nanopores. We use coarse-grained molecular dynamics simulations augmented with analytical theory to study the structural transitions of surface grafted polymer layers (brushes) induced by infiltration of nanoparticles that are attracted to the polymers in the layer. We systematically compare two different polymer brush geometries: one where the polymer chains are grafted to a planar surface and the other where the chains are grafted to the inside of a cylindrical nanochannel. We perform a comprehensive study of the effects of the material parameters such as the polymer chain length, chain grafting density, nanoparticle size, strength of attraction between nanoparticles and polymer monomers, and, in the case of the cylindrically grafted brush, the radius of the cylinder. We find a very general behavioral motif for all geometries and parameter values: the height of the polymer brush is non-monotonic in the nanoparticle concentration in solution. As the nanoparticle concentration increases, the brush height first decreases and after passing through a minimum value begins to increase, resulting in the swelling of the nanoparticle infused brush. These morphological features may be useful for devising tunable “smart” nano-devices whose effective dimensions can be reversibly and precisely adjusted by changing the nanoparticle concentration in solution. The results of approximate Self-Consistent Field Theory (SCFT) calculations, applicable in the regime of strong brush stretching, are compared to the simulation results. The SCFT calculations are found to be qualitatively, even semi-quantitatively, accurate when applied within their intended regime of validity, and provide a useful and efficient tool for modeling such materials.
Development of a two-dimensional binning model for N2–N relaxation in hypersonic shock conditions
Authors: Zhu Tong , Li Zheng , Levin Deborah A.
Published: August 2016

A high fidelity internal energy relaxation model for N2–N suitable for use in direct simulation Monte Carlo (DSMC) modeling of chemically reacting flows is proposed. A novel two-dimensional binning approach with variable bin energy resolutions in the rotational and vibrational modes is developed for treating the internal mode of N2. Both bin-to-bin and state-specific relaxation cross sections are obtained using the molecular dynamics/quasi-classical trajectory (MD/QCT) method with two potential energy surfaces as well as the state-specific database of Jaffe et al. The MD/QCT simulations of inelastic energy exchange between N2 and N show that there is a strong forward-preferential scattering behavior at high collision velocities. The 99 bin model is used in homogeneous DSMC relaxation simulations and is found to be able to recover the state-specific master equation results of Panesi et al. when the Jaffe state-specific cross sections are used. Rotational relaxation energy profiles and relaxation times obtained using the ReaxFF and Jaffe potential energy surfaces (PESs) are in general agreement but there are larger differences between the vibrational relaxation times. These differences become smaller as the translational temperature increases because the difference in the PES energy barrier becomes less important.
On the time dependence of rate coefficients of irreversible reactions between reactants with anisotropic reactivity in liquid solutions
Authors: Ivanov Konstantin L. , Lukzen Nikita N. , Doktorov Alexander B.
Published: August 2016

Time dependence of the rate coefficients of sterically specific reactions is analyzed theoretically. Generally, such reactions exhibit a non-trivial dependence of their rate constant on the steric factor, f < 1, which is defined as the fraction of reactive surface area. Notably, the rate constant of a diffusion-controlled reaction is proportional not to f but, counter-intuitively, to f due to partial averaging of the reaction anisotropy by translational diffusion. Here we demonstrate that the effective steric factor of a diffusion-influenced reaction is strongly time-dependent, increasing from f to f. When reactants have several active sites, these sites “interfere” each other in the sense that the rate constant depends on their relative positions. We demonstrate that such an interference effect is strongly time-dependent as well: it is absent at t = 0 but builds up with time. We argue that the outlined effects are also of importance for calculating the fluorescence quenching rate constants.
Surface diffusion and surface crystal growth of tris-naphthyl benzene glasses
Authors: Ruan Shigang , Zhang Wei , Sun Ye , Ediger M. D. , Yu Lian
Published: August 2016

Surface self-diffusion coefficients of α,α,β-tris-naphthyl benzene (TNB) glasses have been measured using the method of surface grating decay. For 1000 nm wavelength gratings, the decay occurs by viscous flow at temperatures above Tg + 15 K, where Tg is the glass transition temperature (347 K), and by surface diffusion at lower temperatures. Surface diffusion of TNB is vastly faster than bulk diffusion, by a factor of 107 at Tg. Comparing TNB with other molecular glasses, each evaluated at its own Tg, we find that surface diffusion has a greater system-to-system variation than bulk diffusion, slowing down with increasing molecular size and intermolecular hydrogen bonding. Experimentally determined surface diffusion coefficients are in reasonable agreement with those from simulations and theoretical predictions. TNB and other molecular glasses show fast crystal growth on the free surface and the growth velocity is nearly proportional to the surface diffusion coefficient, indicating that the process is supported by surface mobility.
Modeling plasma-assisted growth of graphene-carbon nanotube hybrid
Authors: Tewari Aarti
Published: August 2016

A theoretical model describing the growth of graphene-CNT hybrid in a plasma medium is presented. Using the model, the growth of carbon nanotube (CNT) on a catalyst particle and thereafter the growth of the graphene on the CNT is studied under the purview of plasma sheath and number density kinetics of different plasma species. It is found that the plasma parameter such as ion density; gas ratios and process parameter such as source power affect the CNT and graphene dimensions. The variation in growth rates of graphene and CNT under different plasma power, gas ratios, and ion densities is analyzed. Based on the results obtained, it can be concluded that higher hydrocarbon ion densities and gas ratios of hydrocarbon to hydrogen favor the growth of taller CNTs and graphene, respectively. In addition, the CNT tip radius reduces with hydrogen ion density and higher plasma power favors graphene with lesser thickness. The present study can help in better understanding of the graphene-CNT hybrid growth in a plasma medium.
Polarization controllable multispectral symmetry-breaking absorberin mid-infrared
Authors: Chen Nan , Pitchappa Prakash , Ho Chong Pei , Hasan Dihan , Kropelnicki Piotr , Alioto Massimo , Lee Chengkuo
Published: August 2016

The versatility of mid-infrared metamaterial absorbers along with the ease of fabrication has been widely used in thermal imaging, molecule sensing, and many other applications. Controllable multispectral absorption is highly required for small footprint, multi-purpose, and real-time sensing applications. In this paper, we present the polarization control of interchangeable multispectral absorption based on the dual-band metamaterial absorber in split mode. Large modulation depth of absorption is obtained during multi-band transition through polarization control. We perform theoretical and numerical analysis to explain the results by formulating an equivalent circuit for the asymmetric cross resonator. Thermal controllability is also demonstrated to show the reversible and repeatable manipulation of absorption intensity at a given wavelength. Moreover, we characterized the limitation of this device under extreme high temperature. This work offers a design methodology for interchangeable multispectral metamaterial absorber from a new perspective by adopting polarization of incident light as a control mechanism, and this will open up possibilities for many valuable applications in the future.
Verification of high efficient broad beam cold cathode ion source
Authors: Abdel Reheem A. M. , Ahmed M. M. , Abdelhamid M. M. , Ashour A. H.
Published: August 2016

An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperture is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition.
Novel design for transparent high-pressure fuel injector nozzles
Authors: Falgout Z. , Linne M.
Published: August 2016

The efficiency and emissions of internal combustion (IC) engines are closely tied to the formation of the combustible air-fuel mixture. Direct-injection engines have become more common due to their increased practical flexibility and efficiency, and sprays dominate mixture formation in these engines. Spray formation, or rather the transition from a cylindrical liquid jet to a field of isolated droplets, is not completely understood. However, it is known that nozzle orifice flow and cavitation have an important effect on the formation of fuel injector sprays, even if the exact details of this effect remain unknown. A number of studies in recent years have used injectors with optically transparent nozzles (OTN) to allow observation of the nozzle orifice flow. Our goal in this work is to design various OTN concepts that mimic the flow inside commercial injector nozzles, at realistic fuel pressures, and yet still allow access to the very near nozzle region of the spray so that interior flow structure can be correlated with primary breakup dynamics. This goal has not been achieved until now because interior structures can be very complex, and the most appropriate optical materials are brittle and easily fractured by realistic fuel pressures. An OTN design that achieves realistic injection pressures and grants visual access to the interior flow and spray formation will be explained in detail. The design uses an acrylic nozzle, which is ideal for imaging the interior flow. This nozzle is supported from the outside with sapphire clamps, which reduces tensile stresses in the nozzle and increases the nozzle’s injection pressure capacity. An ensemble of nozzles were mechanically tested to prove this design concept.
Developments of scintillator-based soft x-ray diagnostic in LHD with CsI:Tl and P47 scintillators
Authors: Bando T. , Ohdachi S. , Suzuki Y.
Published: August 2016

Multi-channel soft x-ray (SX) diagnostic has been used in the large helical device (LHD) to research magnetohydrodynamic equilibria and activities. However, in the coming deuterium plasma experiments of LHD, it will be difficult to use semiconductor systems near LHD. Therefore, a new type of SX diagnostic, a scintillator-based type diagnostic, has been investigated in order to avoid damage from the radiation. A fiber optic plate coated by P47 scintillator will be used to detect SX emission. Scintillation light will be transferred by pure silica core optical fibers and detected by photomultiplier tubes. A vertically elongated section of LHD will be covered by a 13 ch. array. Effects from the Deuterium Deuterium neutrons can be negligible when the scintillator is covered by a Pb plate 4 cm in thickness to avoid gamma-rays.
Mechanism of oxidation protection of the Si(001) surface by sub-monolayer Sr template
Authors: Fredrickson Kurt D. , Seo Hosung , Demkov Alexander A.
Published: August 2016

We investigate theoretically the oxidation stability of the Si(001) (2 × 1) reconstructed surface passivated by Sr. Using density functional theory, we find that the Sr surface with ½ monolayer of Sr is protected against oxidation. The presence of Sr delays the oxidation of the surface dimer, and even when the dimer is oxidized, O does not react with the back-bond, preventing the unwanted vertical growth of SiO2. We also show that ¼ monolayer of Sr protects the Si surface in a different way. In the presence of ¼ monolayer of Sr, O atoms are attracted to the Sr-Si dimer complexes, thus preventing the formation of SiO2.
Highly spatially resolved structural and optical investigation of Bi nanoparticles in Y-Er disilicate thin films
Authors: Scarangella A. , Amiard G. , Reitano R. , Priolo F. , Boninelli S. , Miritello M.
Published: August 2016

Er-containing silicon compatible materials have been widely used as infrared emitters for microphotonics application. In this field, the additional introduction of a proper sensitizer permits to increase the Er excitation cross sections, thus increasing its optical efficiency. This work aims to investigate the influence of a post-transition metal, bismuth, on the optical properties of erbium-yttrium disilicate thin films synthesized by magnetron co-sputtering. After thermal treatments at 1000 °C in O2 or N2 environment, the presence of small precipitates, about 6 nm in diameter, was evidenced by transmission electron microscopy analyses. The spatially resolved chemical nature of the nanoparticles was discerned in the Si and O rich environments by means of scanning transmission electron microscopy–energy dispersive X-ray and scanning transmission electron microscopy–electron energy loss spectroscopy analyses performed with nanometric resolution. In particular, metallic Bi nanoparticles were stabilized in the N2 environment, being strongly detrimental for the Er emission. A different scenario was instead observed in O2, where the formation of Bi silicate nanoparticles was demonstrated with the support of photoluminescence excitation spectroscopy. In particular, a broad band peaked at 255 nm, correlated to the excitation band of Bi silicate nanoparticles, was identified in Er excitation spectrum. Thus Bi silicate clusters act as sensitizer for Er ions, permitting to improve Er emission up to 250 times with respect to the resonant condition. Moreover, the Er decay time increases in the presence of the Bi silicate nanoparticles that act as cages for Er ions. These last results permit to further increase Er optical efficiency in the infrared range, suggesting (Bi + Er)-Y disilicate as a good candidate for applications in microphotonics.
Effect of front and back gates on β-Ga2O3 nano-belt field-effect transistors
Authors: Ahn Shihyun , Ren Fan , Kim Janghyuk , Oh Sooyeoun , Kim Jihyun , Mastro Michael A. , Pearton S. J.
Published: August 2016

Field effect transistors (FETs) using SiO2 and Al2O3 as the gate oxides for the back and front sides, respectively, were fabricated on exfoliated two-dimensional (2D) β-Ga2O3 nano-belts transferred to a SiO2/Si substrate. The mechanical exfoliation and transfer process produced nano-belts with smooth surface morphologies and a uniform low defect density interface with the SiO2/Si substrate. The depletion mode nanobelt transistors exhibited better channel modulation with both front and back gates operational compared to either front or back-gating alone. The maximum transconductance was ∼4.4 mS mm−1 with front and back-gating and ∼3.7 mS mm−1 with front-gating only and a maximum drain source current density of 60 mA mm−1 was achieved at a drain-source voltage of 10 V. The FETs had on/off ratios of ∼105 at 25 °C with gate-source current densities of ∼2 × 10−3 mA mm−1 at a gate voltage of −30 V. The device characteristics were stable over more than a month for storage in air ambient and the results show the potential of 2D β-Ga2O3 for power nanoelectronics.
Absorptive lasing mode suppression in ZnO nano- and microcavities
Authors: Wille M. , Michalsky T. , Krüger E. , Grundmann M. , Schmidt-Grund R.
Published: August 2016

We conclusively explain the different lasing mode energies in ZnO nano- and microcavities observed by us and reported in literature. The limited penetration depth of usually used excitation lasers results in an inhomogeneous spatial gain region depending on the structure size and geometry. Hence, weakly or even nonexcited areas remain present after excitation, where modes are instantaneously suppressed by excitonic absorption. We compare the effects for ZnO microwires, nanowires, and tetrapod-like structures at room temperature and demonstrate that the corresponding mode selective effect is most pronounced for whispering-gallery modes in microwires with a hexagonal cross section. Furthermore, the absorptive lasing mode suppression will be demonstrated by correlating the spot size of the excitation laser and the lasing mode characteristic of a single ZnO nanowire.
On the origin of resistive switching volatility in Ni/TiO2/Ni stacks
Authors: Cortese Simone , Trapatseli Maria , Khiat Ali , Prodromakis Themistoklis
Published: August 2016

Resistive switching and resistive random access memories have attracted huge interest for next generation nonvolatile memory applications, also thought to be able to overcome flash memories limitations when arranged in crossbar arrays. A cornerstone of their potential success is that the toggling between two distinct resistance states, usually a High Resistive State (HRS) and a Low Resistive State (LRS), is an intrinsic non-volatile phenomenon with the two states being thermodynamically stable. TiO2 is one of the most common materials known to support non-volatile RS. In this paper, we report a volatile resistive switching in a titanium dioxide thin film sandwiched by two nickel electrodes. The aim of this work is to understand the underlying physical mechanism that triggers the volatile effect, which is ascribed to the presence of a NiO layer at the bottom interface. The NiO layer alters the equilibrium between electric field driven filament formation and thermal enhanced ion diffusion, resulting in the volatile behaviour. Although the volatility is not ideal for non-volatile memory applications, it shows merit for access devices in crossbar arrays due to its high LRS/HRS ratio, which are also briefly discussed.
Fatigue effect on polarization switching dynamics in polycrystalline bulk ferroelectrics
Authors: Zhukov S. , Glaum J. , Kungl H. , Sapper E. , Dittmer R. , Genenko Y. A. , von Seggern H.
Published: August 2016

Statistical distribution of switching times is a key information necessary to describe the dynamic response of a polycrystalline bulk ferroelectric to an applied electric field. The Inhomogeneous Field Mechanism (IFM) model offers a useful tool which allows extraction of this information from polarization switching measurements over a large time window. In this paper, the model was further developed to account for the presence of non-switchable regions in fatigued materials. Application of the IFM-analysis to bipolar electric cycling induced fatigue process of various lead-based and lead-free ferroelectric ceramics reveals different scenarios of property degradation. Insight is gained into different underlying fatigue mechanisms inherent to the investigated systems.
Transistor-based metamaterials with dynamically tunable nonlinear susceptibility
Authors: Barrett John P. , Katko Alexander R. , Cummer Steven A.
Published: August 2016

We present the design, analysis, and experimental demonstration of an electromagnetic metamaterial with a dynamically tunable effective nonlinear susceptibility. Split-ring resonators loaded with transistors are shown theoretically and experimentally to act as metamaterials with a second-order nonlinear susceptibility that can be adjusted through the use of a bias voltage. Measurements confirm that this allows for the design of a nonlinear metamaterial with adjustable mixing efficiency.
Single-beam three-axis atomic magnetometer
Authors: Huang Haichao , Dong Haifeng , Chen Lin , Gao Yang
Published: August 2016

A single-beam atomic magnetometer being operated near zero-field and measuring three-axis fields simultaneously is demonstrated. We produce a rotating field on the x-0-y plane with the frequency of 90 Hz and a modulation field in the z axis at 130 Hz. The rotating field enables a nonzero z axis output when the transverse fields are zeroed using feedback systems. Based on the phase difference of π/2, x and y axes fields can be measured using one lock-in amplifier. Magnetic field sensitivities of 300 fT/Hz1∕2 in x and y axes and 3 pT/Hz1∕2 in the z axis are achieved.
Infrared dielectric function of polydimethylsiloxane and selective emission behavior
Authors: Srinivasan Arvind , Czapla Braden , Mayo Jeff , Narayanaswamy Arvind
Published: August 2016

The complex refractive index of polydimethylsiloxane (PDMS) is determined in the wavelength range between 2.5 μm and 16.7 μm. The parameters of a Drude-Lorentz oscillator model (with 15 oscillators) are extracted from Fourier transform infrared spectroscopy reflectance measurements made on both bulk PDMS and thin films of PDMS deposited on the gold coated silicon substrates. It is shown that thin films of PDMS atop gold exhibit selective emission in the 8 μm to 13 μm atmospheric transmittance window, which demonstrates that PDMS, especially due to its ease of deposition, may be a viable material for passive radiative cooling applications.
Managing Australia’s eucalypt gene pools: assessing the risk of exotic gene flow
Authors: Larcombe Matthew J. , Potts Brad M. , Jones Rebecca C. , Steane Dorothy A. , Silva João Costa E. , Vaillancourt René E.
Published: August 2016

Most eucalypts are endemic to Australia but they have been introduced into more than 100 countries and there are now over 20 million hectares of eucalypt plantations globally. These plantations are grown mainly for pulpwood but there is expanding interest in their use as a renewable source of solid wood products and energy. In Australia, the eucalypt plantation estate is nearing one million hectares, located mainly in temperate regions and dominated by Eucalyptus globulus and E. nitens (subgenus Symphyomyrtus), which are grown mainly outside their natural ranges. While eucalypt species from different major subgenera do not hybridise, hybrids within subgenera are often reported, including hybrids with plantation species. Concerns were raised in the late 1990s that pollen-mediated gene flow from locally exotic plantation eucalypts may affect the integrity of adjacent native eucalypt gene pools. As Australia is the centre-of-origin of most eucalypt species used in plantations around the world, exotic gene flow is one of the many issues that require management for industry sustainability and certification purposes. We here summarise over a decade of research aimed at providing the framework and biological data to help assess and manage the risk of gene flow from these plantations into native gene pools in Australia.
Midgut microbiota and host immunocompetence underlieBacillus thuringiensiskilling mechanism
Authors: Caccia Silvia , Di Lelio Ilaria , La Storia Antonietta , Marinelli Adriana , Varricchio Paola , Franzetti Eleonora , Banyuls Núria , Tettamanti Gianluca , Casartelli Morena , Giordana Barbara , Ferré Juan , Gigliotti Silvia , Ercolini Danilo , Pennacchio Francesco
Published: August 2016

Significance

Bacillus thuringiensisand its toxins are widely used for insect control. Notwithstanding the remarkable importance of this insect pathogen, its killing mechanism has yet to be fully elucidated. Here we show that the microbiota resident in the host midgut triggers a lethal septicemia. The infection process is enhanced by reducing the host immune response and its control on replication of midgut bacteria invading the body cavity through toxin-induced epithelial lesions. The experimental approach used, leaving the midgut microbiota unaltered, allows identification of the bacterial species switching from resident symbionts to pathogens and sets the stage for developing new insect biocontrol technologies based on host immunosuppression as a strategy to enhance the impact of natural antagonists.
Peptide- and proton-driven allosteric clamps catalyze anthrax toxin translocation across membranes
Authors: Das Debasis , Krantz Bryan A.
Published: August 2016

Significance

High-resolution structural information on anthrax toxin allows for elucidation of detailed molecular models of transmembrane translocation. The toxin’s translocase channel component, protective antigen (PA), utilizes a series of polypeptide clamp sites, which serve as binding sites. It is not known how these clamps catalyze the translocation of large proteins while avoiding kinetic traps in which the translocated protein would remain tightly bound inside the channel. Here the clamp sites in PA are revealed to operate allosterically, allowing for the coordination of their activities and the avoidance of kinetic traps that would impede translocation. The ability of the translocating peptide to form a helix correlates with the observed allostery and supports an allosteric helix-compression model for translocation.
Crystallographic snapshots of sulfur insertion by lipoyl synthase
Authors: McLaughlin Martin I. , Lanz Nicholas D. , Goldman Peter J. , Lee Kyung-Hoon , Booker Squire J. , Drennan Catherine L.
Published: August 2016

Significance

Lipoic acid, an enzyme cofactor in central metabolism and a livestock feed supplement, is produced on an industrial scale by a costly multistep synthesis. Nature makes lipoic acid in one step by the chemically challenging addition of two sulfur atoms to an inert fatty acid chain. The sulfur source in this reaction has been controversial, and its identity has implications for engineering microorganisms to overproduce lipoic acid. Structural characterization of a lipoyl synthase enzyme captured in the middle of catalysis shows unequivocally that the enzyme obtains its sulfur atoms by cannibalizing an iron–sulfur cluster, another ancient and essential cofactor. This result reveals an alternative strategy for sulfur mobilization and an unexpected self-sacrificial role for iron–sulfur clusters in biology.
Oxidation and cyclization of casbene in the biosynthesis of
Euphorbia
factors from mature seeds of
Euphorbia lathyris
L.
Authors: Luo Dan , Callari Roberta , Hamberger Britta , Wubshet Sileshi Gizachew , Nielsen Morten T. , Andersen-Ranberg Johan , Hallström Björn M. , Cozzi Federico , Heider Harald , Lindberg Møller Birger , Staerk Dan , Hamberger Björn
Published: August 2016

Significance

Ingenol mebutate is a diterpene ester with a highly complex macrocyclic structure that has been approved for the treatment of actinic keratosis, a precondition of skin cancer. The current production of ingenol mebutate through plant extraction or chemical synthesis is inefficient and costly. Here, we describe the discovery of a biosynthetic route in
Euphorbia lathyris
L. (caper spurge) in which regio-specific oxidation of casbene is followed by an unconventional cyclization to yield jolkinol C, a probable key intermediate in the biosynthesis of macrocyclic diterpenes, including ingenol mebutate. These results can facilitate the biotechnological production of this high-value pharmaceutical and discovery of new biosynthetic intermediates with important bioactivities.
Lens rigidity for manifolds with hyperbolic trapped sets
Authors: Guillarmou Colin
Published: August 2016

For a Riemannian manifold

(
M
,
g
)

(M,g)

with strictly convex boundary

∂
M

\partial M

, the lens data consist of the set of lengths of geodesics

γ
\gamma

with end points on

∂
M

\partial M

, together with their end points

(

x
−

,

x
+

)
∈
∂
M
×
∂
M

(x_-,x_+)\in \partial M\times \partial M

and tangent exit vectors

(

v
−

,

v
+

)
∈

T

x
−

M
×

T

x
+

M

(v_-,v_+)\in T_{x_-} M\times T_{x_+} M

. We show deformation lens rigidity for such manifolds with a hyperbolic trapped set and no conjugate points. This class contains all manifolds with negative curvature and strictly convex boundary, including those with non-trivial topology and trapped geodesics. For the same class of manifolds in dimension

2
2

, we prove that the set of end points and exit vectors of geodesics (i.e., the scattering data) determines the Riemann surface up to conformal diffeomorphism.
Characterization and Pathogenicity of Botryosphaeriaceae Species Isolated from Almond Trees on the Island of Mallorca (Spain)
Authors: Olmo Diego , Armengol Josep , León Maela , Gramaje David
Published: August 2016

In this study, 31 almond orchards with trees showing severe decline symptoms were surveyed from 2009 to 2014 on the island of Mallorca (Spain). In all, 45 Botryosphaeriaceae isolates were collected and characterized based on phenotypical features and comparisons of DNA sequence data of the nuclear ribosomal DNA-internal transcribed spacer region and elongation factor 1-α gene. Five species were identified as Diplodia olivarum, D. seriata, Neofusicoccum luteum, N. mediterraneum, and N. parvum. Pathogenicity tests were performed on four cultivars (‘Pons’, ‘Vivot’, ‘Jordi’, and ‘Ferragnes’) under field conditions for two consecutive years (2013 to 2014), and confirmed that all five species cause canker and dieback of almond, with Neofusicoccum spp. more virulent than Diplodia spp. in both years. Jordi was less sensitive to fungal infection in 2013. First reports from almond in Spain include N. mediterraneum and N. luteum.