bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and anti-tubercular activity of N2-arylbenzo[g]isoquinoline-5,10-dione-3-iminium bromides
Authors: Rotthier G. , Cappoen D. , Nguyen Quang Trung , Dang Thi Tuyet Anh , Mathys V. , Nguyen Van Tuyen , Huygen K. , Maes L. , Cos P. , Abbaspour Tehrani K.
Published: January 2016

The synthesis of a new class of benzo[g]isoquinoline-5,10-diones carrying an amidine functionality and their anti-mycobacterial activities againstMycobacterium tuberculosisH37Rv are reported.
Sustainable development of a surface-functionalized mesoporous aluminosilicate with ultra-high ion exchange efficiency
Authors: Hadi Pejman , Ning Chao , Kubicki James D. , Mueller Karl , Fagan Jonathan W. , Luo Zhengtang , Weng Lutao , McKay Gordon
Published: January 2016

The present work employs a facile hydroxylation technique to efficiently functionalize the surface of a waste-derived aluminosilicate for ultra-high heavy metal uptakeviaion exchange.
Integrated nanotechnology for synergism and degradation of fungicide SOPP using micro/nano-Ag3PO4
Authors: Xue Jingzhe , Zan Guangtao , Wu Qingsheng , Deng Baolin , Zhang Yahui , Huang Hongqin , Zhang Xiaochen
Published: January 2016

The integrated nanotechnology utilizes micro/nano-Ag3PO4 to enhance the antifungal activity of fungicide SOPP and to successively remove the SOPP residue.
Cu2O clusters grown on TiO2 nanoplates as efficient photocatalysts for hydrogen generation
Authors: Zhao Kun , Zhao Shenlong , Qi Jian , Yin Huajie , Gao Chao , Khattak Abdul Muqsit , Wu Yijin , Iqbal Azhar , Wu Lei , Gao Yan , Yu Ranbo , Tang Zhiyong
Published: January 2016

Ultrafine Cu2O nanoclusters are uniformly grown on the surface of TiO2 nanoplates, giving rise to the enhanced photocatalytic H2 evolution via water reduction.
Gold-catalyzed tandem synthesis of bioactive spiro-dipyrroloquinolines and its application in the one-step synthesis of incargranine B aglycone and seneciobipyrrolidine (I)
Authors: Ma Can-Liang , Li Xiao-Hua , Yu Xiao-Long , Zhu Xiao-Long , Hu Yong-Zhou , Dong Xiao-Wu , Tan Bin , Liu Xin-Yuan
Published: January 2016

The Au-catalyzed tandem reaction provided simple and efficient access to spiro-dipyrroloquinolines and incargranine B aglycone and (±)-seneciobipyrrolidine (I).
Enhanced transport of novel crystalline calcium-phosphonate scale inhibitor nanomaterials and their long term flow back performance in laboratory squeeze simulation tests
Authors: Zhang Ping , Kan Amy T. , Tomson Mason B.
Published: January 2016

Prepared crystalline Si–Ca–DTPMP scale inhibitor nanomaterials with enhanced transportability and extended squeeze lifetime potentially for oilfield mineral scale control.
Tailored interfacial architecture of chitosan modified glassy carbon electrodes facilitating selective, nanomolar detection of dopamine
Authors: Rao Vusa Chiranjeevi Srinivasa , Manju Venkatesan , Aneesh K. , Berchmans Sheela , Palaniappan Arumugam
Published: January 2016

Chitosan was tailored directly on the electrode surface to detect DA selectively in nanomolar level at physiological pH.
Substrate dependent photochemical oxidation of monolayer graphene
Authors: Shenoy Ganesh J. , Parobek David , Salim Muhammad , Li Zhiting , Tian Cheng , Liu Haitao
Published: January 2016

In this report we show that the oxidation of monolayer graphene is strongly dependent on its underlying substrate.
Binder-free integration of insoluble cubic CuCl nanoparticles with a homologous Cu substrate for lithium ion batteries
Authors: Liu Song , Hou Hongying , Hu Wen , Liu Xianxi , Duan Jixiang , Meng Ruijin
Published: January 2016

Binder-free integration of a novel insoluble cubic cuprous chloride (CuCl) nanoparticle anode material with homologous Cu foil was designed and achieved via facile in situ electrochemical self-assembly for the first time.
Production of biochars from Ca impregnated ramie biomass (Boehmeria nivea (L.) Gaud.) and their phosphate removal potential
Authors: Liu Shao-bo , Tan Xiao-fei , Liu Yun-guo , Gu Yan-ling , Zeng Guang-ming , Hu Xin-jiang , Wang Hui , Zhou Lu , Jiang Lu-hua , Zhao Bin-bin
Published: January 2016

This work explored the efficiency and mechanisms of phosphate (P) removal by Ca-impregnated biochar prepared from CaCl2-pretreated ramie stem (Ca-RSB) and ramie bark (Ca-RBB).
Theoretical studies on the derivatives of tris([1,2,4]triazolo)[4,3-a:4′,3′-c:4′′,3′′-e][1,3,5]triazine as high energetic compounds
Authors: Zeng Qun , Qu Yanyang , Li Jinshan , Huang Hui
Published: January 2016

Tris([1,2,4]triazolo)[4,3-a:4′,3′-c:4′′,3′′-e][1,3,5]triazine inherited from triazole and triazine is suggested theoretically as a new framework for insensitive and high-energetic materials.
Highly selective and sensitive colorimetric and fluorescent chemosensor of Fe3+ and Cu2+ based on 2,3,3-trimethylnaphto[1,2-d] squaraine
Authors: Wang Yue , Wang Can , Xue Su , Liang Qian , Li Zhongyu , Xu Song
Published: January 2016

2,3,3-trimethylnaphto[1,2-d]pyrrole squaraine (TPSQ) based dual signaling probe was found to exhibit selective colorimetric and fluorescent properties on binding towards Fe3+ and Cu2+ in ethanol/water (4 : 1, v/v) solution, respectively.
A novel bifunctional additive for 5 V-class, high-voltage lithium ion batteries
Authors: Feng Jinkui , Gao Xueping , Ci Lijie , Xiong Shenglin
Published: January 2016

A novel additive is investigated as a bifunctional electrolyte additive for 5 V-class lithium ion batteries.
Preparation and characterization of single crystalline anatase TiO2 films on LSAT (001) by MOCVD
Authors: Wang Mingxian , Wang Weiguang , Li Zhao , Du Xuejian , Feng Xianjin , Xu Haisheng , Zhao Wei , Ma Jin
Published: January 2016

TiO2 thin films with anatase structure have been prepared on [LaAlO3]0.3[SrAl0.5Ta0.5O3]0.7 (LSAT) (001) substrates by metalorganic chemical vapor deposition (MOCVD) in the substrate temperature range of 500–650 °C.
Hydrogenation of lignin-derived phenolic compounds over step by step precipitated Ni/SiO2
Authors: Shu Riyang , Zhang Qi , Xu Ying , Long Jinxing , Ma Longlong , Wang Tiejun , Chen Pengru , Wu Qingyun
Published: January 2016

An efficient and mild process for the hydrogenation of phenolic compounds over step by step precipitated Ni/SiO2 catalyst was presented.
Combined DFT and experimental study of the dispersion and interaction of copper species in Ni-CeO2 nanosized solid solutions
Authors: de Souza Eugenio F. , Chagas Carlos Alberto , Manfro Robinson L. , Souza Mariana M. V. M. , Bicca de Alencastro Ricardo , Schmal Martin
Published: January 2016

Nanosized nickel (Ni) and copper (Cu) doped ceria (CeO2) have attracted attention as solid solutions for energy- and environment-related applications.
Novel benzimidazole–oxadiazole hybrid molecules as promising antimicrobial agents
Authors: Shruthi N. , Poojary Boja , Kumar Vasantha , Hussain Mumtaz Mohammed , Rai Vaishali M. , Pai Vinitha R. , Bhat Mahima , Revannasiddappa B. C.
Published: January 2016

In the present study, we describe the design and expeditious synthesis of novel 2-aryl-5-(3-aryl-[1,2,4]-oxadiazol-5-yl)-1-methyl-1H-benzo[d]imidazole hybrid molecules as promising antimicrobial agents.
Molecular dynamics study on mechanism of preformed particle gel transporting through nanopores: surface hydration
Authors: Zhang Heng , Ma Ying , Hao Qingquan , Wang Hua , Liu Gang , Yuan Shiling
Published: January 2016

Hydration layers induced by silanol groups at silica nanopore surface (a) which served as a physical and energy barrier that keeps PPG away from the pore surface (b). This largely reduced the resistance that PPG has to overcome during transport.
Scalable simultaneous activation and separation of metal–organic frameworks
Authors: Rubio-Martinez Marta , Leong Thomas , Juliano Pablo , Hadley Trevor D. , Batten Michael P. , Polyzos Anastasios , Lim Kok-Seng , Hill Matthew R.
Published: January 2016

Despite the many promising applications of Metal–Organic Frameworks (MOFs) the key advances to boost production to industrial scale still remain elusive.
A new process for enhancing conversion of methyl vinyl ether to propylene yields with Al2O3 hollow spheres
Authors: Wang Yang , Zhang Wenyu , Zha Daoan , Hu Jiaji , Li Wei , Duan Wubiao , Liu Bo
Published: January 2016

The proposed mechanism for a new process to convert methyl vinyl ether to propylene.
Palladium-catalyzed ligand-promoted site-selective cyanomethylation of unactivated C(sp3)–H bonds with acetonitrile
Authors: Liu Yongbing , Yang Ke , Ge Haibo
Published: January 2016

The direct coupling of unactivated sp3C–H bonds in aliphatic amides with acetonitrile was achievedviapalladium catalysis.
Enantioselective assembly of tertiary stereocenters via multicomponent chemoselective cross-coupling of geminal chloro(iodo)alkanes
Authors: Jiang X. , Kulbitski K. , Nisnevich G. , Gandelman M.
Published: January 2016

Catalytic enantioselective method of consecutive Suzuki–Miyaura alkylations of gem-chloro(iodo)alkanes to form two C–C bonds in one pot transformation is described.
Crack patterns over uneven substrates
Authors: Nandakishore Pawan , Goehring Lucas
Published: January 2016

Cracks in thin layers are influenced by what lies beneath them.
Complex flow dynamics around 3D microbot prototypes
Authors: Martínez-Aranda Sergio , Galindo-Rosales Francisco J. , Campo-Deaño Laura
Published: January 2016

A new experimental setup for the study of the complex flow dynamics around 3D microbot prototypes in a straight microchannel has been developed and assessd.
The relationship between local density and bond-orientational order during crystallization of the Gaussian core model
Authors: Li Yan-Wei , Sun Zhao-Yan
Published: January 2016

We found that it is the bond-orientational order rather than local density that triggers the nucleation process, and the relationship between them is strongly impacted by the characterization methods used.
Perovskite solar cells based on bottom-fused TiO2nanocones
Authors: Peng Guiming , Wu Jiamin , Wu Suqin , Xu Xueqing , Ellis James E. , Xu Gang , Star Alexander , Gao Di
Published: January 2016

Compared to the fast electron transport in perovskite and rapid electron injection from perovskite to TiO2nanoparticle scaffold, the slower electron transport rate in mesoporous TiO2is reported to be a hindrance factor for power conversion efficiency.
Flexible high performance hybrid AZO/Ag-nanowire/AZO sandwich structured transparent conductors for flexible Cu(In,Ga)Se2 solar cell applications
Authors: Tsai Wen-Chi , Thomas Stuart R. , Hsu Cheng-Hung , Huang Yu-Chen , Tseng Jiun-Yi , Wu Tsung-Ta , Chang Chia-ho , Wang Zhiming M. , Shieh Jia-Min , Shen Chang-Hong , Chueh Yu-Lun
Published: January 2016

We report on the fabrication of a robust and flexible transparent electrode to replace costly and fragile indium tin oxide used in flexible Cu(In,Ga)Se2 solar cells.
Alkali doping strategies for flexible and light-weight Cu2ZnSnSe4 solar cells
Authors: López-Marino Simón , Sánchez Yudania , Espíndola-Rodríguez Moisés , Alcobé Xavier , Xie Haibing , Neuschitzer Markus , Becerril Ignacio , Giraldo Sergio , Dimitrievska Mirjana , Placidi Marcel , Fourdrinier Lionel , Izquierdo-Roca Victor , Pérez-Rodríguez Alejandro , Saucedo Edgardo
Published: January 2016

Different alkali doping methods to introduce Na and/or K in flexible and light-weight Cu2ZnSnSe4 solar cells were compared. A maximum efficiency of 6.1% was achieved.
Solution-processable thiadiazoloquinoxaline-based donor–acceptor small molecules for thin-film transistors
Authors: Gu Pei-Yang , Zhang Jing , Long Guankui , Wang Zilong , Zhang Qichun
Published: January 2016

The thin-film transistors for compounds 1–3 show typical p-type performance with mobilities of 0.012, 0.05 and 0.0055 cm2 V−1 s−1 and on/off current ratios of 3 × 105, 1 × 106 and 1 × 104, respectively.
Manipulation of carbon nanotube magnetism with metal-rich iron nanoparticles
Authors: Brack N. , Kappen P. , Spencer M. J. S. , Herries A. I. R. , Rider A. N.
Published: January 2016

Metallic Fe nanoparticles (NPs) were electrodeposited onto ozone functionalized carbon nanotubes (CNTs) to produce ferromagnetic carbon nanomaterials.
The hinge domain of the epigenetic repressor Smchd1 adopts an unconventional homodimeric configuration
Authors: Chen Kelan , Czabotar Peter E. , Blewitt Marnie E. , Murphy James M.
Published: January 2016

The structural maintenance of chromosomes (SMC) proteins are fundamental to chromosome organization. They share a characteristic domain structure, featuring a central SMC hinge domain that is critical for forming SMC dimers and interacting with nucleic acids. The structural maintenance of chromosomes flexible hinge domain containing 1 (Smchd1) is a non-canonical member of the SMC family. Although it has been well established that Smchd1 serves crucial roles in epigenetic silencing events implicated in development and disease, much less is known about the structure and function of the Smchd1 protein. Recently, we demonstrated that the C-terminal hinge domain of Smchd1 forms a nucleic acid-binding homodimer; however, it is unclear how the protomers are assembled within the hinge homodimer and how the full-length Smchd1 protein is organized with respect to the hinge region. In the present study, by employing SAXS we demonstrate that the hinge domain of Smchd1 probably adopts an unconventional homodimeric arrangement augmented by an intermolecular coiled coil formed between the two monomers. Such a dimeric structure differs markedly from that of archetypical SMC proteins, raising the possibility that Smchd1 binds chromatin in an unconventional manner.
Role of matrix metalloproteinase-9 in chronic kidney disease: a new biomarker of resistant albuminuria
Authors: Pulido-Olmo Helena , García-Prieto Concha F. , Álvarez-Llamas Gloria , Barderas María G. , Vivanco Fernando , Aranguez Isabel , Somoza Beatriz , Segura Julián , Kreutz Reinhold , Fernández-Alfonso María S. , Ruilope Luis M. , Ruiz-Hurtado Gema
Published: January 2016

Resistant albuminuria, developed under adequate chronic blockade of the renin–angiotensin system, is a clinical problem present in a small number of patients with chronic kidney disease (CKD). The mechanism underlying this resistant albuminuria remains unknown. Matrix metalloproteinases (MMPs) are involved in the pathophysiology of cardiovascular and renal diseases. In the present study we tested the role of MMPs in resistant albuminuria. First we evaluated gelatinase MMP-2 and MMP-9 activity by zymography in the Munich Wistar Frömter (MWF) rat, a model of progressive albuminuria, and subsequently in patients with resistant albuminuria. Markers of oxidative stress were observed in the kidneys of MWF rats, together with a significant increase in pro-MMP-2 and active MMP-9 forms. These changes were normalized together with reduced albuminuria in consomic MWF-8SHR rats, in which chromosome 8 of MWF was replaced with the respective chromosome from spontaneously hypertensive rats. The MMP-2 and MMP-9 protein levels were similar in patients with normal and resistant albuminuria; however, high circulating levels of collagen IV, a specific biomarker of tissue collagen IV degradation, were observed in patients with resistant albuminuria. These patients showed a significant increase in gelatinase MMP-2 and MMP-9 activity, but only a significant increase in the active MMP-9 form quantified by ELISA, which correlated significantly with the degree of albuminuria. Although the expression of the tissue inhibitor of MMP-9 (TIMP)-1 was similar, a novel AlphaLISA assay demonstrated that the MMP-9–TIMP-1 interaction was reduced in patients with resistant albuminuria. It is of interest that oxidized TIMP-1 expression was higher in patients with resistant albuminuria. Therefore, increased circulating MMP-9 activity is associated with resistant albuminuria and a deleterious oxidative stress environment appears to be the underlying mechanism. These changes might contribute to the progression of CKD in these patients.
Client Safety and Telepractice in a Clinic or Home Setting
Authors: Tindall Lyn
Published: January 2016

Telepractice is an exciting addition to the arsenal of speech-language pathologists for delivering services. Efficacy data continues to emerge proving the benefit of using available technology to provide assessment and treatment for persons with a variety of communication disorders, ages, and gender. In addition to providing assessment and treatment using telepractice technology, several professional issues have arisen which must be addressed before implementation of this service delivery system. Licensure and reimbursement have been at the forefront, as well they should. However, client safety is another issue that should also be addressed. Providing speech pathology services in a safe environment is a concept which may not have been considered before technological advances made it possible to provide services to someone while not being physically present.
The RIDBC Telepractice Training Protocol: A Model for Meeting ASHA Roles and Responsibilities
Authors: McCarthy Melissa
Published: January 2016

Telepractice continues to emerge as an acceptable alternative to the provision of in-person services in the fields of speech-language pathology and audiology. In Australia, the Royal Institute for Deaf and Blind Children (RIDBC) has been using telepractice for more than 10 years to meet the needs of children who are deaf and hard of hearing. In order to ensure that the quality of services provided via telepractice is equivalent to that of services provided in-person, RIDBC designed a comprehensive telepractice training protocol. The four-module program corresponds to the roles and responsibilities outlined by the American Speech-Language-Hearing Association (ASHA), and include topics related to the technology, methodology, and pedagogy of working in a telepractice model. The RIDBC training protocol demonstrates one method of supporting practitioners to develop the necessary skills to effectively deliver services via telepractice.
Teletinnitus Program at the VA Gulf Coast Veterans Health Care System
Authors: Tomberlin Constance Hilory
Published: January 2016

There are a multitude of reasons that a teletinnitus program can be beneficial, not only to the patients, but also within the hospital and audiology department. The ability to use technology for the purpose of tinnitus management allows for improved appointment access for all patients, especially those who live at a distance, has been shown to be more cost effective when the patients travel is otherwise monetarily compensated, and allows for multiple patient's to be seen in the same time slots, allowing for greater access to the clinic for the patients wishing to be seen in-house. There is also the patient's excitement in being part of a new technology-based program. The Gulf Coast Veterans Health Care System (GCVHCS) saw the potential benefits of incorporating a teletinnitus program and began implementation in 2013. There were a few hurdles to work through during the beginning organizational process and the initial execution of the program. Since the establishment of the Teletinnitus program, the GCVHCS has seen an enhancement in patient care, reduction in travel compensation, improvement in clinic utilization, clinic availability, the genuine excitement of the use of a new healthcare media amongst staff and patients, and overall patient satisfaction.
Comparison between the particle swarm optimisation and differential evolution approaches for the optimal proportional–integral controllers design during photovoltaic power plants modelling
Authors: Dezelak Klemen , Bracinik Peter , Höger Marek , Otcenasova Alena
Published: January 2016

This study deals with photovoltaic power plant modelling and its integration within the distribution network. It presents a simulation model of a whole photovoltaic power plant including the solar cells, boost converter with maximal power point tracking, voltage‐oriented control and inductor‐capacitor‐inductor (LCL) filter. In such a sense, the applied inverter has many advantages such as a controllable power factor and sinusoidal input current, while the switching frequency of the power switch is relatively high. Therefore, it could cause high‐frequency harmonics around the switching frequency. The traditional way of solving these problems is the usage of LCL filters, where the basic requirement is to achieve sufficient filtering with inductor and capacitor values as small as possible. In addition, emphasis is given to a comparison between two optimisation methods – particle swarm optimisation and differential evolution that are used for the parameters of proportional–integral (PI) controllers determination. These PI controllers represent the main part of the voltage‐oriented control.
Biomimetic channel modeling local vascular dynamics of pro-inflammatory endothelial changes
Authors: Thomas Antony , Daniel Ou-Yang H. , Lowe-Krentz Linda , Muzykantov Vladimir R. , Liu Yaling
Published: January 2016

Endothelial cells form the inner lining of blood vessels and are exposed to various factors like hemodynamic conditions (shear stress, laminar, and turbulent flow), biochemical signals (cytokines), and communication with other cell types (smooth muscle cells, monocytes, platelets, etc.). Blood vessel functions are regulated by interactions among these factors. The occurrence of a pathological condition would lead to localized upregulation of cell adhesion molecules on the endothelial lining of the blood vessel. This process is promoted by circulating cytokines such as tumor necrosis factor-alpha, which leads to expression of intercellular adhesion molecule-1 (ICAM-1) on the endothelial cell surface among other molecules. ICAM-1 is critical in regulating endothelial cell layer dynamic integrity and cytoskeletal remodeling and also mediates direct cell-cell interactions as part of inflammatory responses and wound healing. In this study, we developed a biomimetic blood vessel model by culturing confluent, flow aligned, endothelial cells in a microfluidic platform, and performed real time in situ characterization of flow mediated localized pro-inflammatory endothelial activation. The model mimics the physiological phenomenon of cytokine activation of endothelium from the tissue side and studies the heterogeneity in localized surface ICAM-1 expression and F-actin arrangement. Fluorescent antibody coated particles were used as imaging probes for identifying endothelial cell surface ICAM-1 expression. The binding properties of particles were evaluated under flow for two different particle sizes and antibody coating densities. This allowed the investigation of spatial resolution and accessibility of ICAM-1 molecules expressed on the endothelial cells, along with their sensitivity in receptor-ligand recognition and binding. This work has developed an in vitro blood vessel model that can integrate various heterogeneous factors to effectively mimic a complex endothelial microenvironment and can be potentially applied for relevant blood vessel mechanobiology studies.
Topological analysis of a mixing flow generated by natural convection
Authors: Contreras Pablo Sebastián , de la Cruz Luis Miguel , Ramos Eduardo
Published: January 2016

We use topological tools to describe the natural convective motion and the Lagrangian trajectories of a flow generated by stepwise, alternating heating and cooling protocol of opposite vertical walls of a cubic container. The working fluid considered is Newtonian and the system is in presence of the acceleration of gravity but the nonlinear terms are neglected, i.e., we study the piece-wise steady and linear problem. For this convective mixing flow, we identify invariant surfaces formed by the Lagrangian orbits of massless tracers that are topologically equivalent to spherical shells and period-1 lines with elliptic and hyperbolic segments that are located on symmetry planes. We describe the previous features as functions of the Rayleigh number in the range 3 × 104 ≤ Ra ≤ 5 × 105. We show that this system shares properties with other systems with non-toroidal invariant surfaces.
An immersed boundary method for two-phase fluids and gels and the swimming of Caenorhabditis elegans through viscoelastic fluids
Authors: Lee Pilhwa , Wolgemuth Charles W.
Published: January 2016

The swimming of microorganisms typically involves the undulation or rotation of thin, filamentary objects in a fluid or other medium. Swimming in Newtonian fluids has been examined extensively, and only recently have investigations into microorganism swimming through non-Newtonian fluids and gels been explored. The equations that govern these more complex media are often nonlinear and require computational algorithms to study moderate to large amplitude motions of the swimmer. Here, we develop an immersed boundary method for handling fluid-structure interactions in a general two-phase medium, where one phase is a Newtonian fluid and the other phase is viscoelastic (e.g., a polymer melt or network). We use this algorithm to investigate the swimming of an undulating, filamentary swimmer in 2D (i.e., a sheet). A novel aspect of our method is that it allows one to specify how forces produced by the swimmer are distributed between the two phases of the fluid. The algorithm is validated by comparing theoretical predictions for small amplitude swimming in gels and viscoelastic fluids. We show how the swimming velocity depends on material parameters of the fluid and the interaction between the fluid and swimmer. In addition, we simulate the swimming of Caenorhabditis elegans in viscoelastic fluids and find good agreement between the swimming speeds and fluid flows in our simulations and previous experimental measurements. These results suggest that our methodology provides an accurate means for exploring the physics of swimming through non-Newtonian fluids and gels.
Substituent effects on dynamics at conical intersections: Allene and methyl allenes
Authors: Neville Simon P. , Wang Yanmei , Boguslavskiy Andrey E. , Stolow Albert , Schuurman Michael S.
Published: January 2016

We report a joint experimental and theoretical study on the ultrafast excited state dynamics of allene and a series of its methylated analogues (1,2-butadiene, 1,1-dimethylallene, and tetramethylallene) in order to elucidate the conical intersection mediated dynamics that give rise to ultrafast relaxation to the ground electronic state. We use femtosecond time-resolved photoelectron spectroscopy (TRPES) to probe the coupled electronic-vibrational dynamics following UV excitation at 200 nm (6.2 eV). Ab initio multiple spawning (AIMS) simulations are employed to determine the mechanistic details of two competing dynamical pathways to the ground electronic state. In all molecules, these pathways are found to involve as follows: (i) twisting about the central allenic C–C–C axis followed by pyramidalization at one of the terminal carbon atoms and (ii) bending of allene moiety. Importantly, the AIMS trajectory data were used for ab initio simulations of the TRPES, permitting direct comparison with experiment. For each molecule, the decay of the TRPES signal is characterized by short (30 fs, 52 fs, 23 fs) and long (1.8 ps, 3.5 ps, [306 fs, 18 ps]) time constants for 1,2-butadiene, 1,1-dimethylallene, and tetramethylallene, respectively. However, AIMS simulations show that these time constants are only loosely related to the evolution of electronic character and actually more closely correlate to large amplitude motions on the electronic excited state, modulating the instantaneous vertical ionization potentials. Furthermore, the fully substituted tetramethylallene is observed to undergo qualitatively different dynamics, as displacements involving the relatively massive methyl groups impede direct access to the conical intersections which give rise to the ultrafast relaxation dynamics observed in the other species. These results show that the branching between the “twisting” and “bending” pathways can be modified via the selective methylation of the terminal carbon atoms of allene. The interplay between inertial and potential effects is a key to understanding these dynamical branching pathways. The good agreement between the simulated and measured TRPES confers additional confidence to the dynamical picture presented here.
Ion-kinetic simulations of D-3He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number
Authors: Larroche O. , Rinderknecht H. G. , Rosenberg M. J. , Hoffman N. M. , Atzeni S. , Petrasso R. D. , Amendt P. A. , Séguin F. H.
Published: January 2016

Experiments designed to investigate the transition to non-collisional behavior in D3He-gas inertial confinement fusion target implosions display increasingly large discrepancies with respect to simulations by standard hydrodynamics codes as the expected ion mean-free-paths λc increase with respect to the target radius R (i.e., when the Knudsen number NK=λc/R grows). To take properly into account large NK's, multi-ion-species Vlasov-Fokker-Planck computations of the inner gas in the capsules have been performed, for two different values of NK, one moderate and one large. The results, including nuclear yield, reactivity-weighted ion temperatures, nuclear emissivities, and surface brightness, have been compared with the experimental data and with the results of hydrodynamical simulations, some of which include an ad hoc modeling of kinetic effects. The experimental results are quite accurately rendered by the kinetic calculations in the smaller-NK case, much better than by the hydrodynamical calculations. The kinetic effects at play in this case are thus correctly understood. However, in the higher-NK case, the agreement is much worse. The remaining discrepancies are shown to arise from kinetic phenomena (e.g., inter-species diffusion) occurring at the gas-pusher interface, which should be investigated in the future work.
A generalized Poisson and Poisson-Boltzmann solver for electrostatic environments
Authors: Fisicaro G. , Genovese L. , Andreussi O. , Marzari N. , Goedecker S.
Published: January 2016

The computational study of chemical reactions in complex, wet environments is critical for applications in many fields. It is often essential to study chemical reactions in the presence of applied electrochemical potentials, taking into account the non-trivial electrostatic screening coming from the solvent and the electrolytes. As a consequence, the electrostatic potential has to be found by solving the generalized Poisson and the Poisson-Boltzmann equations for neutral and ionic solutions, respectively. In the present work, solvers for both problems have been developed. A preconditioned conjugate gradient method has been implemented for the solution of the generalized Poisson equation and the linear regime of the Poisson-Boltzmann, allowing to solve iteratively the minimization problem with some ten iterations of the ordinary Poisson equation solver. In addition, a self-consistent procedure enables us to solve the non-linear Poisson-Boltzmann problem. Both solvers exhibit very high accuracy and parallel efficiency and allow for the treatment of periodic, free, and slab boundary conditions. The solver has been integrated into the BigDFT and Quantum-ESPRESSO electronic-structure packages and will be released as an independent program, suitable for integration in other codes.
Energy barriers for dipole moment flipping in PVDF-related ferroelectric polymers
Authors: Yu Ying-Ju , McGaughey Alan J. H.
Published: January 2016

Energy barriers for flipping the transverse dipole moments in poly(vinylidene fluoride) (PVDF) and related copolymers and terpolymers are predicted using the nudged elastic band method. The dipole moments flip individually along the chain, with an order and energy barrier magnitudes (0.1-1.2 eV) that depend on the chain composition and environment. Trifluoroethylene (TrFE) and chlorofluoroethylene (CFE) monomers have larger energy barriers than VDF monomers, while a chain in an amorphous environment has a similar transition pathway as that of an isolated molecule. In a crystalline environment, TrFE and CFE monomers expand the lattice and lower the energy barriers for flipping VDF monomers. This finding is consistent with experimental observations of a large electrocaloric effect in P(VDF-TrFE-CFE) terpolymers.
High efficiency 4H-SiC betavoltaic power sources using tritium radioisotopes
Authors: Thomas Christopher , Portnoff Samuel , Spencer M. G.
Published: January 2016

Realization of an 18.6% efficient 4H-silicon carbide (4H-SiC) large area betavoltaic power source using the radioisotope tritium is reported. A 200 nm 4H-SiC P+N junction is used to collect high-energy electrons. The electron source is a titanium tritide (TiH3x) foil, or an integrated titanium tritide region formed by the diffusion of tritium into titanium. The specific activity of the source is directly measured. Dark current measured under short circuit conditions was less than 6.1 pA/cm2. Samples measured with an external tritium foil produced an open circuit voltage of 2.09 V, short circuit current of 75.47 nA/cm2, fill factor of 0.86, and power efficiency of 18.6%. Samples measured with an integrated source produced power efficiencies of 12%. Simulations were done to determine the beta spectrum (modified by self absorption) exiting the source and the electron hole pair generation function in the 4H-SiC. The electron-hole pair generation function in 4H-SiC was modeled as a Gaussian distribution, and a closed form solution of the continuity equation was used to analyze the cell performance. The effective surface recombination velocity in our samples was found to be 105–106 cm/s. Our analysis demonstrated that the surface recombination dominates the performance of a tritium betavoltaic device but that using a thin P+N junction structure can mitigate some of the negative effects.
Phase-only laser control in the weak-field limit: Two-pulse control of IBr photofragmentation revisited
Authors: Tiwari Ashwani K. , Henriksen Niels E.
Published: January 2016

We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible, starting from a single vibrational eigenstate, after the interaction with two laser pulses—at a fixed time delay—both operating in the weak-field limit. Thus, phase dependence in the interaction with the second fixed-energy phase-modulated pulse persists after the pulse is over. This is illustrated for the nonadiabatic process: I + Br*←IBr → I + Br, where the relative yield of excited Br* can be changed by pure phase modulation. Furthermore, a strong frequency dependence of the branching ratio is observed and related to the re-crossing dynamics of the avoided crossing in the above-mentioned process.
Perturbed Hankel determinant, correlation functions and Painlevé equations
Authors: Chen Min , Chen Yang , Fan Engui
Published: January 2016

In this paper, we continue with the study of the Hankel determinant, generated by a Pollaczek-Jacobi type weight, w(x; t, α, β) ≔ xα(1 − x)βe−t/x, x ∈ [0, 1], α > 0, β > 0, t ≥ 0. This reduces to the “pure” Jacobi weight at t = 0. It was shown in the work of Chen and Dai [J. Approximation Theory 162(2), 2149–2167 (2010)] that the logarithmic derivative of this Hankel determinant satisfies a Jimbo-Miwa-Okamoto σ-form of Painlevé V (PV). We show that, under a double scaling, where n the dimension of the Hankel matrix tends to ∞ and t tends to 0, such that s ≔ 2n2t is finite, the double scaled Hankel determinant (effectively an operator determinant) has an integral representation in terms of a particular PIII′. Expansions of the scaled Hankel determinant for small and large s are found. We also consider another double scaling with α = − 2n + λ, where n → ∞, and t tends to 0, such that s ≔ nt is finite. In this situation, the scaled Hankel determinant has an integral representation in terms of a particular PV, and its small and large s asymptotic expansions are also found. The reproducing kernel in terms of monic polynomials orthogonal with respect to the Pollaczek-Jacobi type weight under the origin (or hard edge) scaling may be expressed in terms of the solutions of a second order linear ordinary differential equation (ODE). With special choices of the parameters, the limiting (double scaled) kernel and the second order ODE degenerate to Bessel kernel and the Bessel differential equation, respectively.
Terahertz antenna electronic chopper
Authors: Sterczewski L. A. , Grzelczak M. P. , Plinski E. F.
Published: January 2016

In this paper, we present an electronic circuit used to bias a photoconductive antenna that generates terahertz radiation. The working principles and the design process for the device are discussed in detail. The noise and shape of the wave measurements for a built device are considered. Furthermore, their impact on a terahertz pulse and its spectra is also examined. The proposed implementation is simple to build, robust and offers a real improvement over THz instrumentation due to the frequency tuning. Additionally, it provides for galvanic isolation and ESD protection.
A unified free-form representation applied to the shape optimization of the hohlraum with octahedral 6 laser entrance holes
Authors: Jiang Shaoen , Huang Yunbao , Jing Longfei , Li Haiyan , Huang Tianxuan , Ding Yongkun
Published: January 2016

The hohlraum is very crucial for indirect laser driven Inertial Confinement Fusion. Usually, its shape is designed as sphere, cylinder, or rugby with some kind of fixed functions, such as ellipse or parabola. Recently, a spherical hohlraum with octahedral 6 laser entrance holes (LEHs) has been presented with high flux symmetry [Lan et al., Phys. Plasmas 21, 010704 (2014); 21, 052704 (2014)]. However, there is only one shape parameter, i.e., the hohlraum to capsule radius ratio, being optimized. In this paper, we build the hohlraum with octahedral 6LEHs with a unified free-form representation, in which, by varying additional shape parameters: (1) available hohlraum shapes can be uniformly and accurately represented, (2) it can be used to understand why the spherical hohlraum has higher flux symmetry, (3) it allows us to obtain a feasible shape design field satisfying flux symmetry constraints, and (4) a synthetically optimized hohlraum can be obtained with a tradeoff of flux symmetry and other hohlraum performance. Finally, the hohlraum with octahedral 6LEHs is modeled, analyzed, and then optimized based on the unified free-form representation. The results show that a feasible shape design field with flux asymmetry no more than 1% can be obtained, and over the feasible design field, the spherical hohlraum is validated to have the highest flux symmetry, and a synthetically optimal hohlraum can be found with closing flux symmetry but larger volume between laser spots and centrally located capsule.
Discrete photon implementation for plasma simulations
Authors: Fierro Andrew , Stephens Jacob , Beeson Sterling , Dickens James , Neuber Andreas
Published: January 2016

The self-produced light emission from pulsed plasma discharges and its impact on plasma development are challenging to characterize through simulation and modeling, chiefly due to the large number of radiating species and limited computer memory. Often, photo-processes, such as photo-ionization or photo-emission of electrons, are implemented through over-simplifying approximations or neglected altogether. Here, a method applicable to plasma simulations is implemented in a Particle-in-Cell /Monte Carlo Collision model, which is capable of discretely tracking photons and their corresponding wavelengths. Combined with the appropriate cross sections or quantum yields, a wavelength dependent model for photo-ionization or photo-emission may be implemented. Additionally, by resolving the wavelengths of each photon, an emission spectrum for a region of interest may be generated. Simulations for a pure nitrogen environment reveal that the calculated emission profile of the second positive system agrees well with the experimental spectrum of a pulsed, nanosecond discharge in the same spectral region.
Plasma expansion into a vacuum with an arbitrarily oriented external magnetic field
Authors: García-Rubio F. , Ruocco A. , Sanz J.
Published: January 2016

Plasma expansion into a vacuum with an external magnetic field is studied under the ideal magnetohydrodynamic hypothesis. The inclination of the magnetic field with respect to the expansion direction is arbitrary, and both the perpendicular and the oblique cases are separately analyzed. A self-similar solution satisfying the boundary conditions is obtained. The interface with the vacuum is treated as a fluid surface, and jump conditions concerning the momentum conservation are imposed. The effect of the intensity of the magnetic field and its inclination is thoroughly studied, and the consistency of the solution for small and large inclinations is investigated.
Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment
Authors: Fonseca I. C. , Bakke K.
Published: January 2016

Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels.
Second harmonic generation by self-focusing of intense hollow Gaussian laser beam in collisionless plasma
Authors: Purohit Gunjan , Rawat Priyanka , Gauniyal Rakhi
Published: January 2016

The effect of self focused hollow Gaussian laser beam (HGLB) (carrying null intensity in center) on the excitation of electron plasma wave (EPW) and second harmonic generation (SHG) has been investigated in collisionless plasma, where relativistic-ponderomotive and only relativistic nonlinearities are operative. The relativistic change of electron mass and the modification of the background electron density due to ponderomotive nonlinearity lead to self-focusing of HGLB in plasma. Paraxial ray theory has been used to derive coupled equations for the self focusing of HGLB in plasma, generation of EPW, and second harmonic. These coupled equations are solved analytically and numerically to study the laser intensity in the plasma, electric field associated with the excited EPW, and the power of SHG. Second harmonic emission is generated due to nonlinear coupling between incident HGLB and EPW satisfying the proper phase matching conditions. The results show that the effect of including the ponderomotive nonlinearity is significant on the generation of EPW and second harmonic. The electric field associated with EPW and the power of SHG are found to be highly sensitive to the order of the hollow Gaussian beam.
A high figure of merit vibrational energy harvester for low frequency applications
Authors: Nico V. , Boco E. , Frizzell R. , Punch J.
Published: January 2016

Small-scale vibration energy harvesters that respond efficiently at low frequencies are challenging to realize. This paper describes the design and implementation of one such harvester, which achieves a high volumetric Figure of Merit (FoMv = 2.6% at 11.50 Hz) at the scale of a C-type battery and outperforms other state-of-the-art devices in the sub 20 Hz frequency range. The device employs a 2 Degree-of-Freedom velocity-amplified approach and electromagnetic transduction. The harvester comprises two masses oscillating one inside the other, between four sets of magnetic springs. Collisions between the two masses transfer momentum from the heavier to the lighter mass, exploiting velocity amplification. The paper first presents guidelines for designing and optimizing the transduction mechanism, before a nonlinear numerical model for the system dynamics is developed. Experimental characterisation of the harvester design is then presented to validate both the transducer optimization and the dynamics model. The resulting high FoMV demonstrates the effectiveness of the device for low frequency applications, such as human motion.
Inertio-elastic mixing in a straight microchannel with side wells
Authors: Hong Sun Ok , Cooper-White Justin J. , Kim Ju Min
Published: January 2016

Mixing remains a challenging task in microfluidic channels because of their inherently small length scale. In this work, we propose an efficient microfluidic mixer based on the chaotic vortex dynamics of a viscoelastic flow in a straight channel with side wells. When the inertia and elasticity of a dilute polymer solution are balanced (i.e., the Reynolds number Re and Weissenberg number Wi are both on the order of 101), chaotic vortices appear in the side wells (inertio-elastic flow instability), enhancing the mixing of adjacent fluid streams. However, there is no chaotic vortex motion in Newtonian flows for any flow rate. Efficient mixing by such an inertio-elastic instability is found to be relevant for a wide range of Re values.
Control of VO•• ∼ TiTi′ dipole pairs as well as MgTi″ defects on dielectric properties of Mg doped (Pb0.35Sr0.65)TiO3 thin film
Authors: Hu Tao , Wang Zongrong , Ma Ning , Du Piyi
Published: January 2016

Mg doped (Pb0.35Sr0.65)TiO3 (PST) thin films were fabricated on indium tin oxide /glass substrates by the sol–gel technique. The formation of the PST phase and control of the magnesium doping on the microstructure, defect states, and dielectric properties of the thin film were investigated by means of XRD, SEM, AFM, XPS, and impedance analysis. Results showed that the oxygen vacancies and the associated Ti3+ ions formed as VO•• ∼ TiTi′ dipole pairs, and the dipole pairs were aligned opposite to the direction of the intrinsic dipole moments in the PST thin film. The amount of dipole pairs was strongly affected by the formed MgTi″ in the thin film. The minimum amount of the dipole pairs appeared in the PST thin film with Mg doping content of 6% in molar ratio. The thin film with Mg doping content of 6% showed high permittivity due to low offset from VO•• ∼ TiTi′ dipole pairs and low dielectric loss due to low defect electrons generated in the thin film simultaneously. The formed MgTi″ in the oxygen octahedral contributed lower response of the dipole moments to external electric field and resulted in lower tunability of the PST thin film with increasing Mg doping content. Controlled by the substitution of Mg2+ ions for Ti4+ ions and the induced VO•• ∼ TiTi′ dipole pairs, the optimal figure of merit was obtained in the PST thin film with Mg doping content of 6% with which the thin film possessed the smallest dielectric loss and still high tunability simultaneously.
Molecular Electronics: History and Fundamentals
Authors: Marqués-González Santiago , Low Paul J.
Published: January 2016

The increasing difficulties of meeting ‘Moore’s Law’ rates of progress in conventional semiconductor electronics, coupled with the advent of methods capable of measuring the electronic properties of single molecules in a laboratory setting, have seen a surge of activity in the field of molecular electronics over the last decade. However, the concepts of molecular electronics are far from new, and the basic premise and ideas of molecular electronics have been shadowing those of solid-state semiconductor electronics since the middle of the 20th century. In this Primer Review, we introduce the topic of molecular electronics, drawing on some of the earliest expressions of the fundamental concepts, and summarizing key concepts to provide the interested reader with an entry to this fascinating field of science and emerging technology.