bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly-efficient photocatalytic degradation of methylene blue by PoPD-modified TiO
2
nanocomposites due to photosensitization-synergetic effect of TiO2 with PoPD
Authors: Yang Chuanxi , Dong Wenping , Cui Guanwei , Zhao Yingqiang , Shi Xifeng , Xia Xinyuan , Tang Bo , Wang Weiliang
Published: June 2017

Poly-o-phenylenediamine modified TiO2 nanocomposites were successfully synthesized via an ‘in situ’ oxidative polymerization method. The modified nanocomposites were characterized by BET, XRD, TEM, FT-IR, TGA, XPS, EA and UV-Vis DRS. The photocatalytic degradation of methylene blue was chosen as a model reaction to evaluate the photocatalytic activities of TiO2 and PoPD/TiO2. The results indicated that PoPD/TiO2 nanocomposites exhibited good photocatalytic activity and stability. The photocatalytic activity of PoPD/TiO2 increased as the initial pH increased because of electrostatic adsorption between the photocatalyst and MB as well as the generation of ·OH, whereas it exhibited an earlier increasing and later decreasing trend as the concentration of the photocatalyst increased owing to the absorption of visible light. The photocatalytic stability of the PoPD/TiO2 nanocomposite was dependent on the stability of its structure. Based on radical trapping experiments and ESR measurements, the origin of oxidizing ability of PoPD/TiO2 nanocomposites on photocatalytic degradation of MB was proposed, which taking into account of ·OH and ·O2− were the first and second important ROS, respectively. The possible photocatalytic mechanism and photocatalytic activity enhanced mechanism has been proposed, taking into account the photosensitization effect and synergetic effect of TiO2 with PoPD.
A change in the aggregation pathway of bovine serum albumin in the presence of arginine and its derivatives
Authors: Borzova Vera A. , Markossian Kira A. , Kleymenov Sergey Yu. , Kurganov Boris I.
Published: June 2017

Chemical chaperones including arginine and its derivatives are widely used by biochemists working on the design of agents, which are able to efficiently suppress protein aggregation. To elucidate the mechanisms of anti-aggregation activity of chemical chaperones, methods based on registration of the increment in light scattering intensity must be supplemented with methods for direct detection of the portion of aggregated protein (γagg). For this purpose asymmetric flow field-flow fractionation was used in the present work. It was shown that heat-induced aggregation of bovine serum albumin (BSA) followed the kinetics of the reaction of the second order (0.1 M sodium phosphate buffer, pH 7.0, 70 °C). It was proposed to use Rhvs γagg plots to characterize the aggregation pathway (Rh is the hydrodynamic radius of the protein aggregates, which was calculated from the dynamic light scattering data). The changes in the shape of Rhvs γagg plots in the presence of arginine, arginine amide and arginine ethyl ester are indicative of the changes in the aggregation pathway of BSA aggregation. A conclusion has been made that larger aggregates are formed in the presence of arginine hydrochloride and its derivatives.
Expression of the Human Herpesvirus 6A Latency-Associated Transcript U94A Disrupts Human Oligodendrocyte Progenitor Migration
Authors: Campbell Andrew , Hogestyn Jessica M. , Folts Christopher J. , Lopez Brittany , Pröschel Christoph , Mock David , Mayer-Pröschel Margot
Published: June 2017

Progression of demyelinating diseases is caused by an imbalance of two opposing processes: persistent destruction of myelin and myelin repair by differentiating oligodendrocyte progenitor cells (OPCs). Repair that cannot keep pace with destruction results in progressive loss of myelin. Viral infections have long been suspected to be involved in these processes but their specific role remains elusive. Here we describe a novel mechanism by which HHV-6A, a member of the human herpesvirus family, may contribute to inadequate myelin repair after injury.
Correction: Corrigendum: Characterization of the first double-stranded RNA bacteriophage infecting Pseudomonas aeruginosa
Authors: Yang Yuhui , Lu Shuguang , Shen Wei , Zhao Xia , Shen Mengyu , Tan Yinling , Li Gang , Li Ming , Wang Jing , Hu Fuquan , Le Shuai
Published: June 2017

Scientific Reports 6: Article number: 38795; published online: 09 December 2016; updated: 15 June 2017. This Article contains a typographical error in the Materials and Methods section, under subheading ‘Nucleotide sequence accession number’, “The accession numbers for segments L, M, and S are KX07420, KX074202, and KX074203, respectively”.
Development of a HPLC-DAD method combined with multicomponent chemometrics and antioxidant capacity to monitor the quality consistency of compound bismuth aluminate tablets by comprehensive quantified fingerprint method
Authors: Yang Fangliang , Sun Guoxiang , Chen Jiao
Published: June 2017

A high performance liquid chromatography (HPLC) coupled with diode array detector method was developed to monitor the quality consistency of a classical compound preparation, compound bismuth aluminate tablet.
Chrysanthemum flower-like NiCo2O4–nitrogen doped graphene oxide composite: an efficient electrocatalyst for lithium–oxygen and zinc–air batteries
Authors: Moni Prabu , Hyun Suyeon , Vignesh Ahilan , Shanmugam Sangaraju
Published: June 2017

Facile preparation and application of a simple and cost-effective chrysanthemum flower-like NCO/N-rGO composite material as an efficient and stable cathode catalyst for an aqueous zinc–air and non-aqueous lithium–oxygen batteries.
An enantioselective cascade for simultaneous generation of five quaternary stereocenters from fully substituted enones
Authors: Yang Shu-Mei , Reddy Ganapuram Madhusudhan , Wang Tzu-Ping , Yeh Yu-Sheng , Wang Min , Lin Wenwei
Published: June 2017

A highly stereoselective organocatalytic cascade is developed for efficient synthesis of polycyclic compounds bearing five quaternary stereocenters.
Adaptability of the metal(iii,iv) 1,2,3-trioxobenzene rod secondary building unit for the production of chemically stable and catalytically active MOFs
Authors: Mouchaham Georges , Abeykoon Brian , Giménez-Marqués Mónica , Navalon Sergio , Santiago-Portillo Andrea , Affram Maame , Guillou Nathalie , Martineau Charlotte , Garcia Hermenegildo , Fateeva Alexandra , Devic Thomas
Published: June 2017

Metal-1,2,3-trioxobenzene rod secondary building units are robust enough to adapt to cations of various charges.
Monitoring aggregation of a pH-responsive polymer via proton exchange
Authors: Chakraborty Ipsita , Mukherjee Ishita , Haldar Ujjal , De Priyadarsi , Bhattacharyya Rangeet
Published: June 2017

The interfacial proton exchange detected by NMR is shown to provide insights into micellar aggregation process.
Influence of HMW tail chains on the structural evolution of HDPE induced by second melt penetration
Authors: Zhu Chun-Xia , Xia Xiao-Chao , Huang Yan-Hao , Xie Dan-Dan , Chen Rui , Yang Ming-Bo
Published: June 2017

Hierarchical double skin–core structures were formed in the polyethylene injected samples and their orientation didn't increase monotonically with increasing high molecular weight (HMW) tail content under the special shear and temperature profiles.
Improved magnetic and magnetoelectric properties in BaFe12O19 nanostructures
Authors: Xu Xingyu , Huang Fengzhen , Shao Ye , Zhou Min , Ren Xianming , Lu Xiaomei , Zhu Jinsong
Published: June 2017

Improved magnetism and magnetodielectric coupling are obtained in plate-like BaFe12O19 nanoparticles because of their larger structural distortion.
Excited state characterization of carbonyl containing carotenoids: a comparison between single and multireference descriptions
Authors: Spezia Riccardo , Knecht Stefan , Mennucci Benedetta
Published: June 2017

Multireference DFT/MRCI calculations elucidate the role of the CO group in the low-lying singlet excited state spectrum of carbonyl-containing carotenoids.
Surface enhanced resonance Raman spectroscopy of iron Hangman complexes on electrodes during electrocatalytic oxygen reduction: advantages and problems of common drycast methods
Authors: Götz R. , Ly H. K. , Wrzolek P. , Schwalbe M. , Weidinger I. M.
Published: June 2017

The structure of drycast Hangman complexes on electrodes during electrocatalytic oxygen reduction was investigated with surface enhanced Raman spectro-electrochemistry.
Preparation of tetrazine-containing [2 + 1] complexes of 99mTc and in vivo targeting using bioorthogonal inverse electron demand Diels–Alder chemistry
Authors: Yazdani Abdolreza , Janzen Nancy , Czorny Shannon , Ungard Robert G. , Miladinovic Tanya , Singh Gurmit , Valliant John F.
Published: June 2017

A new 99mTc-labelled tetrazine for targeted imaging using bioorthogonal chemistry was developed and evaluated in vivo using a trans-cyclooctene derived bisphosphonate targeting regions of high bone turnover and bone lesions.
A reduced graphene oxide/covalent cobalt porphyrin framework for efficient oxygen reduction reaction
Authors: Zuo Quan , Cheng Gongzhen , Luo Wei
Published: June 2017

A series of pyridine-functionalized reduced graphene oxide (G-dye)/cobalt–porphyrin covalent organic framework (CoCOF) hybrids have been synthesized and assayed as efficient electrocatalysts toward oxygen reduction reaction.
Correction: Entrainment of nanosized clusters from a nanopowder fluidized bed
Authors: Fabre Andrea , Clemente Alberto , Balas Francisco , Lobera M. Pilar , Santamaría Jesús , Kreutzer Michiel T. , van Ommen J. Ruud
Published: June 2017

Correction for ‘Modeling the size distribution in a fluidized bed of nanopowder’ by Andrea Fabre et al., Environ. Sci.: Nano, 2017, 4, 670–678.
Linking classical and molecular optomechanics descriptions of SERS
Authors: Schmidt Mikołaj K. , Esteban Ruben , Benz Felix , Baumberg Jeremy J. , Aizpurua Javier
Published: June 2017

The surface-enhanced Raman scattering (SERS) of molecular species in plasmonic cavities can be described as an optomechanical process where plasmons constitute an optical cavity of reduced effective mode volume which effectively couples to the vibrations of the molecules. An optomechanical Hamiltonian can address the full quantum dynamics of the system, including the phonon population build-up, the vibrational pumping regime, and the Stokes–anti-Stokes correlations of the photons emitted. Here we describe in detail two different levels of approximation to the methodological solution of the optomechanical Hamiltonian of a generic SERS configuration, and compare the results of each model in light of recent experiments. Furthermore, a phenomenological semi-classical approach based on a rate equation of the phonon population is demonstrated to be formally equivalent to that obtained from the full quantum optomechanical approach. The evolution of the Raman signal with laser intensity (thermal, vibrational pumping and instability regimes) is accurately addressed when this phenomenological semi-classical approach is properly extended to account for the anti-Stokes process. The formal equivalence between semi-classical and molecular optomechanics descriptions allows us to describe the vibrational pumping regime of SERS through the classical cross sections which characterize a nanosystem, thus setting a roadmap to describing molecular optomechanical effects in a variety of experimental situations.
Identification of microRNA precursors using reduced and hybrid features
Authors: Khan Asad , Shah Sajid , Wahid Fazli , Khan Fiaz Gul , Jabeen Saima
Published: June 2017

We have developed a predictor called MicroR-Pred in which the RNA sequences are formulated by a hybrid feature vector.
Cu(ii)-grafted SBA-15 functionalized S-methylisothiourea aminated epibromohydrin (SBA-15/E-SMTU-CuII): a novel and efficient heterogeneous mesoporous catalyst
Authors: Jahanshahi R. , Akhlaghinia B.
Published: June 2017

The catalytic activity of novel synthesized SBA-15/E-SMTU-CuII nanocatalyst was investigated for the green, one-pot, pseudo five-component synthesis of tetrahydropyridine derivatives.
Design of well-defined shape memory networks with high homogeneity: towards advanced shape memory polymeric materials
Authors: Li Xingjian , Pan Yi , Lai Jingjuan , Wu Ruiqing , Zheng Zhaohui , Ding Xiaobin
Published: June 2017

A well-defined shape memory network with high homogeneity was engineered via step-growth thiol-norbornene photopolymerization.
Structural insights into the alternative oxidases: are all oxidases made equal?
Authors: May Benjamin , Young Luke , Moore Anthony L.
Published: June 2017

The alternative oxidases (AOXs) are ubiquinol-oxidoreductases that are members of the diiron carboxylate superfamily. They are not only ubiquitously distributed within the plant kingdom but also found in increasing numbers within the fungal, protist, animal and prokaryotic kingdoms. Although functions of AOXs are highly diverse in general, they tend to play key roles in thermogenesis, stress tolerance (through the management of radical oxygen species) and the maintenance of mitochondrial and cellular energy homeostasis. The best structurally characterised AOX is from Trypanosoma brucei. In this review, we compare the structure of AOXs, created using homology modelling, from many important species in an attempt to explain differences in activity and sensitivity to AOX inhibitors. We discuss the implications of these findings not only for future structure-based drug design but also for the design of novel AOXs for gene therapy.
Scissor sisters: regulation of ADAM10 by the TspanC8 tetraspanins
Authors: Matthews Alexandra L. , Szyroka Justyna , Collier Richard , Noy Peter J. , Tomlinson Michael G.
Published: June 2017

A disintegrin and metalloprotease 10 (ADAM10) is a ubiquitously expressed transmembrane protein which is essential for embryonic development through activation of Notch proteins. ADAM10 regulates over 40 other transmembrane proteins and acts as a ‘molecular scissor’ by removing their extracellular regions. ADAM10 is also a receptor for α-toxin, a major virulence factor of Staphylococcus aureus. Owing to the importance of its substrates, ADAM10 is a potential therapeutic target for cancer, neurodegenerative diseases such as Alzheimer's and prion diseases, bacterial infection and inflammatory diseases such as heart attack, stroke and asthma. However, targetting ADAM10 is likely to result in toxic side effects. The tetraspanins are a superfamily of 33 four-transmembrane proteins in mammals which interact with and regulate specific partner proteins within membrane nanodomains. Tetraspanins appear to have a cone-shaped structure with a cholesterol-binding cavity, which may enable tetraspanins to undergo cholesterol-regulated conformational change. An emerging paradigm for tetraspanin function is the regulation of ADAM10 by the TspanC8 subgroup of tetraspanins, namely Tspan5, 10, 14, 15, 17 and 33. This review will describe how TspanC8s are required for ADAM10 trafficking from the endoplasmic reticulum and its enzymatic maturation. Moreover, different TspanC8s localise ADAM10 to different subcellular localisations and may cause ADAM10 to adopt distinct conformations and cleavage of distinct substrates. We propose that ADAM10 should now be regarded as six different scissor proteins depending on the interacting TspanC8. Therapeutic targetting of specific TspanC8/ADAM10 complexes could allow ADAM10 targetting in a cell type- or substrate-specific manner, to treat certain diseases while minimising toxicity.
Role of ESCRT component HD-PTP/PTPN23 in cancer
Authors: Gingras Marie-Claude , Kazan Jalal M. , Pause Arnim
Published: June 2017

Sustained cellular signalling originated from the receptors located at the plasma membrane is widely associated with cancer susceptibility. Endosomal sorting and degradation of the cell surface receptors is therefore crucial to preventing chronic downstream signalling and tumorigenesis. Since the Endosomal Sorting Complexes Required for Transport (ESCRT) controls these processes, ESCRT components were proposed to act as tumour suppressor genes. However, the bona fide role of ESCRT components in tumorigenesis has not been clearly demonstrated. The ESCRT member HD-PTP/PTPN23 was recently identified as a novel haplo-insufficient tumour suppressor in vitro and in vivo, in mice and humans. In this mini-review, we outline the role of the ESCRT components in cancer and summarize the functions of HD-PTP/PTPN23 in tumorigenesis.
Growing functions of the ESCRT machinery in cell biology and viral replication
Authors: Scourfield Edward J. , Martin-Serrano Juan
Published: June 2017

The vast expansion in recent years of the cellular processes promoted by the endosomal sorting complex required for transport (ESCRT) machinery has reinforced its identity as a modular system that uses multiple adaptors to recruit the core membrane remodelling activity at different intracellular sites and facilitate membrane scission. Functional connections to processes such as the aurora B-dependent abscission checkpoint also highlight the importance of the spatiotemporal regulation of the ESCRT machinery. Here, we summarise the role of ESCRTs in viral budding, and what we have learned about the ESCRT pathway from studying this process. These advances are discussed in the context of areas of cell biology that have been transformed by research in the ESCRT field, including cytokinetic abscission, nuclear envelope resealing and plasma membrane repair.
Sensorless speed estimation of permanent magnet DC brushed motor considering the effect of armature teeth–slots and commutation
Authors: Ghosh Mousam , Ghosh Suman , Saha Pradip Kumar , Panda Goutam Kumar
Published: June 2017

This study proposes a novel technique of speed estimation for permanent magnet direct current (PMDC) brushed motor. The impact of armature teeth–slots and commutation of PMDC motor on armature current is considered in this study to estimate the speed. In many applications, speed measurement of motors is essentially required. Conventionally mechanical sensors are coupled to the motor shaft for speed measurement. Recently many sensorless methods for speed estimation of motor had been introduced. This study proposes a new method where the variation in effective magnetic path reluctance due to continuous alternation in teeth–slots positions with respect to stationery poles is considered. Combined effects of effective magnetic path reluctance variation and armature commutation cause ripple in armature current. In this study, the effect of teeth–slots in armature current is investigated using finite‐element approach and also it is verified experimentally. Furthermore, an elementary circuitry is included in this study in support of the proposed method from armature current. The performed test on a 24 V–100 W brushed PMDC motor indicates that the proposed method is effective in wide range of speed estimation considering the effect of change in mechanical load or terminal voltage level.
Dynamic analysis of a floating hybrid spar tension leg platform concept for wind monitoring applications in deep sea
Authors: Micallef Marisa , Sant Tonio , Mollicone Pierluigi
Published: June 2017

This study presents an investigation to assess the motions experienced by a floating hybrid spar‐tension leg platform structure when supporting a wind‐monitoring lattice tower in deep water conditions of the Central Mediterranean. The numerical study is based on the software package ANSYS® AQWA™. The structure supports a 30 m wind‐monitoring tower as well as a LiDAR system. A parametric analysis was carried out for different geometrical and met‐ocean conditions, and the simulations were restricted to regular (single frequency) wave and constant wind speed conditions only. The Morison formulation was used to resolve the hydrodynamic loads in a time domain. The study shows how the natural periods of the floating wind‐monitoring mast structure decrease with increasing buoyancy‐to‐weight ratios. From the time‐series simulations, it was evident that slender spars experience smaller displacements. This is a favourable result as it results in more reliable wind measurements taken by the cup‐type anemometers. Finally, a sensitivity analysis was carried out to examine the variations of surge motion predictions resulting from deviations in the hydrodynamic coefficients. It was observed that the platform surge motion is more sensitive to deviations in the added mass coefficient than the drag coefficient.
Perspectives on the Psychosocial Management of Oromandibular Dystonia
Authors: Siegel Lauren , Page Allyson
Published: June 2017

Oromandibular dystonia (OMD) is a rare disorder of movement characterized by tonic muscle contractions that can result in involuntary, repetitive, and patterned muscle contractions of the lingual musculature, labial musculature, and/or muscles of mastication. As a result, dysarthria can be present that can lead to reduced speech intelligibility and have an adverse impact on psychosocial functioning. In this article, we will describe the clinical and speech characteristics of OMD and the various methods of treatment. Then we will introduce and describe patient-reported outcome measures that assess two aspects of psychosocial functioning: communicative participation and quality of life. We will describe the current state of knowledge as it relates to communicative participation and quality of life in this clinical population, and, finally, we will advocate that speech-language pathologists have a unique role in the care of individuals with OMD through the inclusion of patient-reported outcome measures to provide a comprehensive and holistic management plan.
Speech Recognition as a Practice Tool for Dysarthria
Authors: Fager Susan
Published: June 2017

Recovery of speech in dysarthria requires an extensive amount of time and practice. Speech recognition (SR) technology may support long-term practice and speech recovery efforts for individuals with dysarthria. However, SR technology development has been focused on typical (neurologically intact) speakers to support writing. This article describes the history and development of SR technology, how it has been used by individuals with dysarthria, and includes a case study illustration of the use of a novel SR technology as a speech practice tool. Case study participants included two individuals with differing onsets and dysarthria due to traumatic brain injury. Results indicated that both were able to make acoustic/perceptual changes during speech practice sessions, and one participant demonstrated generalization of changes to habitual speech. Limitations and future directions of current SR technology as a speech practice tool are discussed.
Patient-Provider Communication Training for Dysarthria: Lessons Learned from Student Trainees
Authors: Baylor Carolyn , Yorkston Kathryn , Burns Michael
Published: June 2017

Patient-provider communication skills training programs rarely include content addressing how health care providers can improve communication with patients exhibiting dysarthria and other communication disorders. Consequently, these patients often struggle to access quality health care services. This article describes a training program focused on giving health care students the opportunity to interact with standardized patients portraying dysarthria and aphasia. A summary of the program's outcome is then provided from the perspective of the students involved as well as lessons students taught us about how to continue improving this type of program and to make it a more universal part of health care education.
Preliminary Investigations Showing Venous Thromboembolism Recurrence in Patients with Residual Venous Obstruction in Singaporean Population
Authors: Er Chaozer , Chong Claudia , Chin Han , Chin Tay , Sule Ashish
Published: June 2017

This study aims to determine the association of residual venous obstruction (RVO) with recurrent venous thromboembolism (VTE). A retrospective cohort study was conducted determining if RVO on ultrasonography is associated with recurrent VTE in a Singaporean population. The subjects were identified from the Vascular Diagnostic Laboratory patients' record of Tan Tock Seng Hospital (TTSH), Singapore between 2008 and 2013. All the patients included had RVO after 3 months of anticoagulation. Data such as age, gender, race, thrombus location, etiology, history of malignancy, thrombophilia screen, treatment duration, and follow-up were recorded for analysis. Statistical analysis was performed using Stata/SE 13.1 (StataCorp LLC). The study was approved by the National Healthcare Group Domain Specific Review Board (DSRB), Singapore. Out of the 34 patients who had RVO, 6 (17.6%) developed VTE recurrence. Patients were treated with anticoagulation for a mean time of 24.5 months. The mean follow-up time for VTE recurrence was 25.4 months. Out of the six patients who had VTE recurrence, one had common iliac vein involvement, four had superficial femoral vein and common femoral vein involvement, zero had popliteal vein involvement, and one had calf veins involvement. There was a significant association between thrombophilia (p = 0.0195) and malignancy (p = 0.020) at inclusion with the risk of recurrent VTE. The presence of RVO after 3 months of anticoagulation is likely to increase the risk of VTE recurrence. Larger studies with RVO are needed to evaluate if there is an increased risk of VTE recurrence in the Asian population.
Bi-enhanced N incorporation in GaAsNBi alloys
Authors: Occena J. , Jen T. , Rizzi E. E. , Johnson T. M. , Horwath J. , Wang Y. Q. , Goldman R. S.
Published: June 2017

We have examined the influence of bismuth (Bi) and nitrogen (N) fluxes on N and Bi incorporation during molecular-beam epitaxy of GaAs1-x-yNxBiy alloys. The incorporation of Bi is found to be independent of N flux, while the total N incorporation and the fraction of N atoms occupying non-substitutional lattice sites increase with increasing Bi flux. A comparison of channeling nuclear reaction analysis along the [100], [110], and [111] directions with Monte Carlo-Molecular Dynamics simulations indicates that the non-substitutional N primarily incorporate as (N-As)As interstitial complexes. We discuss the influence of Bi adatoms on the formation of arsenic-terminated [110]-oriented step-edges and the resulting enhancement in total N incorporation via the formation of additional (N-As)As.
The role of multivalency in the association kinetics of patchy particle complexes
Authors: Newton Arthur C. , Groenewold Jan , Kegel Willem K. , Bolhuis Peter G.
Published: June 2017

Association and dissociation of particles are elementary steps in many natural and technological relevant processes. For many such processes, the presence of multiple binding sites is essential. For instance, protein complexes and regular structures such as virus shells are formed from elementary building blocks with multiple binding sites. Here we address a fundamental question concerning the role of multivalency of binding sites in the association kinetics of such complexes. Using single replica transition interface sampling simulations, we investigate the influence of the multivalency on the binding kinetics and the association mechanism of patchy particles that form polyhedral clusters. When the individual bond strength is fixed, the kinetics naturally is very dependent on the multivalency, with dissociation rate constants exponentially decreasing with the number of bonds. In contrast, we find that when the total bond energy per particle is kept constant, association and dissociation rate constants turn out rather independent of multivalency, although of course still very dependent on the total energy. The association and dissociation mechanisms, however, depend on the presence and nature of the intermediate states. For instance, pathways that visit intermediate states are less prevalent for particles with five binding sites compared to the case of particles with only three bonds. The presence of intermediate states can lead to kinetic trapping and malformed aggregates. We discuss implications for natural forming complexes such as virus shells and for the design of artificial colloidal patchy particles.
Explicit treatment of hydrogen bonds in the universal force field: Validation and application for metal-organic frameworks, hydrates, and host-guest complexes
Authors: Coupry Damien E. , Addicoat Matthew A. , Heine Thomas
Published: June 2017

A straightforward means to include explicit hydrogen bonds within the Universal Force Field (UFF) is presented. Instead of treating hydrogen bonds as non-bonded interaction subjected to electrostatic and Lennard-Jones potentials, we introduce an explicit bond with a negligible bond order, thus maintaining the structural integrity of the H-bonded complexes and avoiding the necessity to assign arbitrary charges to the system. The explicit hydrogen bond changes the coordination number of the acceptor site and the approach is thus most suitable for systems with under-coordinated atoms, such as many metal-organic frameworks; however, it also shows an excellent performance for other systems involving a hydrogen-bonded framework. In particular, it is an excellent means for creating starting structures for molecular dynamics and for investigations employing more sophisticated methods. The approach is validated for the hydrogen bonded complexes in the S22 dataset and then employed for a set of metal-organic frameworks from the Computation-Ready Experimental database and several hydrogen bonded crystals including water ice and clathrates. We show that the direct inclusion of hydrogen bonds reduces the maximum error in predicted cell parameters from 66% to only 14%, and the mean unsigned error is similarly reduced from 14% to only 4%. We posit that with the inclusion of hydrogen bonding, the solvent-mediated breathing of frameworks such as MIL-53 is now accessible to rapid UFF calculations, which will further the aim of rapid computational scanning of metal-organic frameworks while providing better starting points for electronic structure calculations.
Hybrid-PIC modeling of laser-plasma interactions and hot electron generation in gold hohlraum walls
Authors: Thoma C. , Welch D. R. , Clark R. E. , Rose D. V. , Golovkin I. E.
Published: June 2017

The walls of the hohlraum used in experiments at the national ignition facility are heated by laser beams with intensities ∼1015 W/cm2, a wavelength of ∼1/3 μm, and pulse lengths on the order of a ns, with collisional absorption believed to be the primary heating mechanism. X-rays generated by the hot ablated plasma at the gold walls are then used to implode a target in the hohlraum interior. In addition to the collisional absorption of laser energy at the walls, non-linear laser-plasma interactions (LPI), such as stimulated Raman scattering and two plasmon decay, are believed to generate a population of supra-thermal electrons which, if present in the hohlraum, can have a deleterious effect on target implosion. We describe results of hohlraum modeling using a hybrid particle-in-cell code. To enable this work, new particle-based algorithms for a multiple-ion magneto-hydrodynamic (MHD) treatment, and a particle-based ray-tracing model were developed. The use of such hybrid methods relaxes the requirement to resolve the laser wavelength, and allows for relatively large-scale hohlraum simulations with a reasonable number of cells. But the non-linear effects which are believed to be the cause of hot electron generation can only be captured by fully kinetic simulations with good resolution of the laser wavelength. For this reason, we employ a two-tiered approach to hohlraum modeling. Large-scale simulations of the collisional absorption process can be conducted using the fast quasi-neutral MHD algorithm with fluid particle species. From these simulations, we can observe the time evolution of the hohlraum walls and characterize the density and temperature profiles. From these results, we can transition to smaller-scale highly resolved simulations using traditional kinetic particle-in-cell methods, from which we can fully model all of the non-linear laser-plasma interactions, as well as assess the details of the electron distribution function. We find that vacuum hohlraums should be stable to both two plasmon decay and stimulated Raman scattering instabilities for intensities ≤1015 W/cm2. In gas-filled hohlraums, shocks may be induced in the blowoff gold plasma, which leads to more complex density and temperatures profiles. The resulting effect on LPI stability depends strongly on the details of the profile, and it is possible for the gas-filled hohlraum to become unstable to two plasmon decay at 1015 W/cm2 if the quarter-critical surface reaches temperatures exceeding 1 keV.
Design and simulation of a sub-terahertz folded-waveguide extended interaction oscillator
Authors: Liu Wenxin , Zhang Zhaochuan , Zhao Chao , Guo Xin , Liao Suying
Published: June 2017

In this paper, an interesting type of a two-section folded wave-guide (TSFW) slow wave structure (SWS) for the development of sub-Terahertz (sub-THz) extended interaction oscillator (EIO) is proposed. In this sub-THz device, the prebunching electron beam is produced by the TSFW SWS, which results in the enhancement of the output power. To verify this concept, the TSFW for sub-THz EIO is developed, which includes the design, simulation, and some fabrications. A small size of electron optics system (EOS), the TSFW SWS for beam-wave interactions, and the output structure are studied with simulations. Through the codes Egun and Superfish, the EOS is designed and optimized. With a help of CST studio and 3D particle-in-cell (PIC) simulation CHIPIC, the characteristics of beam-wave interaction generated by the TSFW are studied. The results of PIC simulation show that the output power is remarkably enhanced by a factor of 3, which exceeds 200 W at the frequency of 108 GHz. Based on the optimum parameters, the TSFW is manufactured with a high speed numerical mill, and the test transmission characteristic |S21| is 13 dB. At last, the output structure with a pill-box window is optimized, fabricated, integrated, and tested, and the result shows that the voltage standing-wave ratio of the window is about 2.2 at an operating frequency of 108 GHz. This design and simulation can provide an effective method to develop high power THz sources.
Temporal profile of betatron radiation from laser-driven electron accelerators
Authors: Horný Vojtěch , Nejdl Jaroslav , Kozlová Michaela , Krůs Miroslav , Boháček Karel , Petržílka Václav , Klimo Ondřej
Published: June 2017

The temporal profile of X-ray betatron radiation was theoretically studied for the parameters available with current laser systems. Characteristics of the betatron radiation were investigated for three different configurations of laser wakefield acceleration: typical self-injection regime and optical injection regime with perpendicularly crossed injection and drive beams, both achievable with 100 TW class laser, and ionization injection regime with a sub-10 TW laser system that was experimentally verified. Constructed spectrograms demonstrate that X-ray pulse durations are in the order of few tens of femtoseconds and the optical injection case reveals the possibility of generating X-ray pulses as short as 2.6 fs. The X-ray pulse duration depends mainly on the length of the trapped electron bunch as the emitted photons copropagate with the bunch with nearly the same velocity. These spectrograms were calculated using a novel simplified method based on the theory of Liénard-Wiechert potentials. It takes advantage of the fact that the electron oscillates transversally in the accelerating plasma wave in the wiggler regime and, thus, emits radiation almost exclusively in the turning points of its sine-like trajectory. Therefore, there are only few very narrow time intervals, which contribute significantly to the emission of radiation, while the rest can be neglected. These narrow time intervals are determined from the electron trajectories calculated using particle-in-cell simulations and the power spectrum at given point in far field is computed for each electron using the Fourier transform. Spectrograms of the emitted radiation are constructed by summing contributions of individual particles, since the incoherent nature of the electron bunch is assumed.
Thin-film magnetless Faraday rotators for compact heterogeneous integrated optical isolators
Authors: Karki Dolendra , Stenger Vincent , Pollick Andrea , Levy Miguel
Published: June 2017

This report describes the fabrication, characterization, and transfer of ultra-compact thin-film magnetless Faraday rotators to silicon photonic substrates. Thin films of magnetization latching bismuth-substituted rare-earth iron garnets were produced from commercially available materials by mechanical lapping, dice polishing, and crystal-ion-slicing. Eleven-μm-thick films were shown to retain the 45° Faraday rotation of the bulk material to within 2° at 1.55 μm wavelength without re-poling. Anti-reflection coated films evince 0.09 dB insertion loses and better than –20 dB extinction ratios. Lower extinction ratios than the bulk are ascribed to multimode propagation. Significantly larger extinction ratios are predicted for single-mode waveguides. Faraday rotation, extinction ratios, and insertion loss tests on He-ion implanted slab waveguides of the same material yielded similar results. The work culminated with bond alignment and transfer of 7 μm-thick crystal-ion-sliced 50 × 480 μm2 films onto silicon photonic substrates.
Reduced pulse energy for frequency comb offset stabilization with a dual-pitch periodically poled lithium niobate ridge waveguide
Authors: Hitachi K. , Hara K. , Tadanaga O. , Ishizawa A. , Nishikawa T. , Gotoh H.
Published: June 2017

The pulse energy for stabilizing the carrier-envelop offset frequency of an Er-doped fiber laser was reduced by a dual-pitch (DP-) periodically poled lithium niobate (PPLN) ridge waveguide implemented in a 2f-to-3f self-referencing interferometer (SRI). The pulse energy requirement was less than half that for a single-pitch PPLN ridge waveguide implemented in an f-to-2f SRI. We also found that environmental noise could be reduced by adjusting the pulse energy for frequency stabilization with the DP-PPLN ridge waveguide, as estimated from the phase noise of an out-of-loop interferometer.
A broadband acoustic metamaterial with impedance matching layer of gradient index
Authors: Ding Yihang , Statharas Eleftherios Christos , Yao Kui , Hong Minghui
Published: June 2017

Narrowband transmission of some acoustic metamaterials limits their device applications. Here, we propose and demonstrate a broadband acoustic metamaterial comprising a space coiling structure by introducing an impedance-matching layer between air and the metamaterial. The impedance-matching layer is achieved by especially designing the parameters of the space coiling structure to form a gradient index. It is found that the metamaterial with the impedance matching layers substantially improves energy transmission in the frequency range of 2–6 kHz. We also show the capability of such a metamaterial to modulate the phase of acoustic waves with high energy transmission up to at least 60%.
Modulation of acousto-electric current using a hybrid on-chip AlN SAW/GFET device
Authors: Liang Ji , Yang Xing , Zheng Shijun , Sun Chongling , Zhang Menglun , Zhang Hao , Zhang Daihua , Pang Wei
Published: June 2017

We fabricated a hybrid on-chip acousto-electric (AE) and field-effect device to investigate the modulation of acoustic carrier transportation by gate voltage. The device fabrication exploited a surface micromachining aluminum nitride process on a silicon wafer, facilitating an integration of a surface acoustic wave (SAW) delay line and a graphene field-effect transistor. The SAW device induced an AE current in graphene, which scales linearly with the input power and remains essentially constant when subtracting the offset current at different DC biases. At a constant DC bias, the AE current can be modulated by the gate voltage, due to the change of the carrier mobility in graphene. A four-fold enhancement in the AE current was realized when ∼35 V voltage was applied to the gate electrode. The highly integrated device proves to be a powerful tool to understand the AE current in graphene, and since it supports integration for versatile functionality, it opens an avenue to explore the properties of diverse nanomaterials.
Assessing the optimal conditions for surface-mediated disinfection of Influenza A virus solutions
Authors: Mannelli Ilaria , Janner Davide , Sagués Francesc , Reigada Ramon
Published: June 2017

Environmental contextTransmission of viruses is related to their survival while being outside the host body. By means of experimental and computational simulations we assess the optimal conditions for virus deactivation upon contact with particularly functionalised substrates. These results constitute the basis for the design of new surfaces with high antiviral activity that can be important in public or sensitive environments such as in hospitals where the contamination and spreading of viruses are a critical issue.
AbstractThe abundance of pathogenic microorganisms in the environment and the ease of their transmission through several paths is a critical issue in many daily human activities. Within the different transmission paths, contact with contaminated surfaces provides a chance for the development of surfaces with special characteristics that are able to reduce the spread of microorganisms through their deactivation by contact. The development of ‘active’ surfaces with antiviral properties requires the understanding of the molecular interaction mechanisms between functionalised surfaces and lipid-enveloped entities. By means of a study based on experimental and computational methods we have assessed that surfaces that are simultaneously hydrophobic and oleophilic are more efficient for disinfecting aqueous virus solutions. The combination of these features causes the disruption of the viral lipid envelope upon contacting the surface, and as a consequence the virus’ destruction and deactivation. Our results suggest new and more effective design strategies for functionalised surfaces that may be of interest for applications in sensitive environments.
Effect of attitudes towards patients on sexual history taking: a survey of Iranian–American physicians in California, USA
Authors: Rashidian Mitra , Minichiello Victor , Knutsen Synnove F. , Ghamsary Mark
Published: June 2017

Background: Although obtaining sexual history from patients is essential, the attitudes of physicians can become a barrier to sexual health care. Iranian–American physicians may face particular challenges because talking about sexuality is considered a taboo within their culture. Our study examined these physicians’ attitudes when taking a sexual history from their patients. Methods: In 2013, a self-administrated questionnaire was sent to 1550 Iranian–American physicians in California, USA. Using factor analysis, the principal components approach with a Varimax rotation was used on a set of 12-item questions (five-point Likert scales) to detect latent factors that explain attitudes affecting sexual history taking. Scores are generated to determine physicians’ attitudes towards sexual history taking. Results: In total, 354 questionnaires were returned (23% response rate). Three factors were identified as internally consistent (Cronbach’s α = 0.84 – 0.94): (1) attitude towards various patients; (2) female sexuality; and (3) age and marriage. Significant association were found between these three factors and some variables such as physicians’ gender, country of medical graduation, religion, birthplace and age. Conclusions: Results revealed that cultural attitudes are important factors affecting physicians’ involvement in sexual history taking. Additional studies from this population and other subpopulations of US physicians are needed. New strategies that reflect on physicians’ attitude on sexual healthcare delivery is needed. If confirmed in other studies, our findings could have implications for the training of medical graduates globally.
Economic perspectives on nitrogen in farming systems: managing trade-offs between production, risk and the environment
Authors: Pannell David J.
Published: June 2017

Economic insights are crucial for making sound decisions about farm-level management of nitrogen and also about regional or national policy such as for water pollution. In the present review, key insights are presented from a large and diverse literature on the economics of nitrogen in agriculture and the economics of the consequences of nitrogen fertilisation. Issues covered include (1) the economics of nitrogen as an input to production, (2) nitrogen and economic risk at the farm level, (3) the economics of nitrogen fixation by legumes, (4) the existence of flat payoff functions, which often allow wide flexibility in decisions about nitrogen fertiliser rates, (5) explanations for over-application of nitrogen fertilisers by some farmers, and (6) the economics of nitrogen pollution at both the farm level and the policy level. Economics helps to explain farmer behaviour and to design strategies and policies that are more beneficial and more likely to be adopted and successfully implemented.
Providing perches for predatory and aggressive birds appears to reduce the negative impact of frugivorous birds in vineyards
Authors: Peisley Rebecca K. , Saunders Manu E. , Luck Gary W.
Published: June 2017

Context Birds active in vineyards in south-eastern Australia can reduce or enhance crop yields via their foraging activities (e.g. by consuming grapes or by preying on grape-eating species). Aims We examined the effectiveness of artificial perches in encouraging predatory birds into vineyards to scare frugivorous birds and consequently reduce the damage they cause to grapes. Methods We monitored 12 artificial perches for 4 months during the growing season, spread over six vineyards in north-eastern Victoria, and compared bird damage to grapes at these sites with control sites without perches. Key results We found that raptors did not use the artificial perches. However, the large and aggressive Australian magpie (Cracticus tibicen) commonly used perches and we recorded 38513 perch visits by this species. Grapevines around perch sites suffered >50% less grape damage (4.13% damage per bunch) than control sites (8.57% damage per bunch). Conclusions Our results suggest that providing artificial perches in vineyards can play a role in reducing frugivore damage to grapes. However, the effectiveness of perches can vary under different environmental conditions and certain perch types are not suitable for all predatory or aggressive birds. Implications Future research should focus on the potential role of large-bodied and competitively aggressive species such as the Australian magpie in altering the activity of smaller frugivorous birds in vineyards, and also on the optimum height and location of artificial perches within vineyards to increase visitation by other predatory or aggressive bird species.
Cupriphication of gold to sensitize d
10
–d
10
metal–metal bonds and near-unity phosphorescence quantum yields
Authors: Galassi Rossana , Ghimire Mukunda M. , Otten Brooke M. , Ricci Simone , McDougald Roy N. , Almotawa Ruaa M. , Alhmoud Dieaa , Ivy Joshua F. , Rawashdeh Abdel-Monem M. , Nesterov Vladimir N. , Reinheimer Eric W. , Daniels Lee M. , Burini Alfredo , Omary Mohammad A.
Published: June 2017

Significance

Closed-shell metal–metal bonds are experimentally and theoretically substantiated as bona fide polar-covalent/ligand-unassisted/ground-state Cu(I)–Au(I) d
10
–d
10
bonds. Counterintuitively, replacing some of the gold content with copper leads to stronger metal–metal bonding (despite the lesser relativistic effects in Cu vs. Au) and higher phosphorescence quantum efficiency [despite much lower spin-orbit coupling constants (
ξ

SOC

) for 3d vs. 5d orbitals]. The former results are attributed to greater orbital mixing between (n+1)s/p orbitals of one metal with filled nd
10
orbitals of the other metal in the heterometallic vs. homometallic system, whereas the near-unity photoluminescence quantum yields and higher extinction coefficients in mixed-metal (Au/Cu) heterometallic vs. homometallic systems are attributed to symmetry reduction. The latter results are promising for enabling societally useful technologies (e.g., Ir-/rare-earth-free LEDs).