bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of unsymmetrical B2E2 and B2E3 heterocycles by borylene insertion into boradichalcogeniranes
Authors: Liu Siyuan , Légaré Marc-André , Hofmann Alexander , Rempel Anna , Hagspiel Stephan , Braunschweig Holger
Published: March 2019

Unsymmetrically substituted cyclic diboron chalcogenides have been successfully prepared through the direct insertion of a borylene moiety into E–E bonds.
Design rules for encapsulating proteins into complex coacervates
Authors: Blocher McTigue Whitney C. , Perry Sarah L.
Published: March 2019

We explore using two-polymer coacervation to encapsulate model proteins and present design rules to guide encapsulation of novel targets.
Strongly coupled polypyrrole/molybdenum oxide hybrid films via electrochemical layer-by-layer assembly for pseudocapacitors
Authors: Zhang Ming-Yue , Song Yu , Guo Di , Yang Duo , Sun Xiaoqi , Liu Xiao-Xia
Published: March 2019

A strongly coupled layer-by-layer (LbL) PPy/MoOx hybrid film is demonstrated. The spectroscopy results indicate the protonation level of PPy is enhanced and the valence state of Mo in MoOx is reduced, which synergistically improve the charge transfer kinetics of the composites.
In situ formation of zeolitic-imidazolate framework thin films and composites using modified polymer substrates
Authors: Abdul Hamid Mohamad Rezi , Park Sunghwan , Kim Ju Sung , Lee Young Moo , Jeong Hae-Kwon
Published: March 2019

In situ formation of multifunctional MOF thin films and composites using the PMMOF process.
One-step fabrication of silver nanosphere-wetted carbon nanotube electrodes via electric-field-driven combustion waves for high-performance flexible supercapacitors
Authors: Yeo Taehan , Lee Jaeho , Shin Dongjoon , Park Seonghyun , Hwang Hayoung , Choi Wonjoon
Published: March 2019

Electric-field driven combustion waves yield completely wetted hybrids of single-crystalline, spherical Ag particles and multi-walled carbon nanotubes for high-performance supercapacitors.
As-cast ternary polymer solar cells based on a nonfullerene acceptor and its fluorinated counterpart showing improved efficiency and good thickness tolerance
Authors: Pan Feilong , Zhang Lianjie , Jiang Haiying , Yuan Dong , Nian Yaowen , Cao Yong , Chen Junwu
Published: March 2019

PBDB-T-SF : IDIC : ID4F ternary blend films show 11.52% power conversion efficiency, higher than 9.39% and 10.35% for the corresponding binary devices.
Rational design and kinetics study of flexible sodium-ion full batteries based on binder-free composite film electrodes
Authors: Zhang Keliang , Zhang Xudong , He Wen , Xu Wangning , Xu Guogang , Yi Xinli , Yang Xuena , Zhu Jiefang
Published: March 2019

Flexible sodium-ion full batteries were rationally designed by using hard carbon fibers from carbonized filter paper as a conductive supporting framework.
La(OH)3 nanosheet-supported CoPt nanoparticles: a highly efficient and magnetically recyclable catalyst for hydrogen production from hydrazine in aqueous solution
Authors: Wang Kun , Yao Qilu , Qing Shaojun , Lu Zhang-Hui
Published: March 2019

Bimetallic CoPt nanoparticles supported on shape-controlled La(OH)3 were synthesized by a one-step co-reduction synthetic process and used as a highly effective and magnetically recyclable catalyst for the selective decomposition of hydrous hydrazine.
Response to the letter regarding the hypothesis paper “Much ado about N…atrium: modelling tissue sodium as a highly sensitive marker of subclinical and localised oedema”
Authors: Rossitto Giacomo , Touyz Rhian M. , Petrie Mark C. , Delles Christian
Published: March 2019

This short article provides a comment on the recent letter by G. Bhave regarding our hypothesis paper [Clinical Science (2018) 132, 2609–2613].
High‐order ridge reconstruction for more accurate signal estimate from time‐frequency representations
Authors: Zhu Xiangxiang , Zhang Zhuosheng , Li Wenting , Li Bei
Published: March 2019

Ridge reconstruction (RR) method is one of the most commonly used ways for non‐stationary signal reconstruction from time‐frequency representations. However, this method leads to a large reconstruction error when dealing with strongly amplitude‐modulated and frequency‐modulated (AM–FM) signals. To tackle this problem, in this Letter the authors propose a new and powerful reconstruction approach, named high‐order RR, by considering the high‐order derivative information of amplitude and phase of the signal. In particular, an explicit reconstruction formula for second‐order RR is derived. Simulation results demonstrate the superiority of the proposed approach in reconstruction accuracy when addressing AM–FM signals, as well as the stability for the selection of window width.
Cellular automaton simulation of vehicles in the contraflow left‐turn lane at signalised intersections
Authors: Chen Qun , Yi Jiaxuan , Wu Yuli
Published: March 2019

To improve the capacity of signalised intersections for left‐turn vehicles, an unconventional left‐turn design named the contraflow left‐turn lane is applied at intersections in several cities of China. The main concept of the design is to provide more capacity for left‐turn vehicles by dynamically making use of the adjacent opposite lanes. In this study, a cellular automaton model that simulates left‐turn traffic flow at a signalised intersection with a contraflow left‐turn lane was developed and verified by field data. Rules for vehicles entering the contraflow left‐turn lane were proposed, and various factors including the vehicle type, driver type, and the ratio of U‐turn vehicles were considered. The simulation results showed that the contraflow left‐turn lane could increase the capacity of the intersection and decrease the delay of left‐turn vehicles. Also, the optimal match between the length of the contraflow left‐turn lane and the duration of the pre‐signal green light can be evaluated via simulation. This study can provide a reference for the actual application of contraflow left‐turn lanes.
Revisiting the cosmic-ray induced Venusian ionization with the Atmospheric Radiation Interaction Simulator (AtRIS)
Authors: Herbst Konstantin , Banjac Saša , Nordheim Tom A.
Published: March 2019

Context.Cosmic ray bombardment represents a major source of ionization in planetary atmospheres. The higher the energy of the primary cosmic ray particles, the deeper they can penetrate into the atmosphere. In addition, incident high energy cosmic ray particles induce extensive secondary particle cascades (“air showers”) that can contain up to several billion secondary particles per incoming primary particle. To quantify cosmic ray-induced effects on planetary atmospheres it is therefore important to accurately model the entire secondary particle cascade. This is particularly important in thick planetary atmospheres where the secondary particle cascades can develop extensively before being absorbed by the surface.

Aims.Inside the Venusian atmosphere, cosmic rays are the dominant driver for the ionization below an altitude of ~100 km. In this work we revisit the numerical modeling of the galactic and solar cosmic-ray induced atmospheric ionization for cosmic ray ions from Hydrogen (Z= 1) to Nickel (Z= 28) and investigate the influence of strong solar energetic particle events inside the Venusian atmosphere.

Methods.The Atmospheric Radiation Interaction Simulator (AtRIS), a newly developed simulation code to model the interaction of the near-(exo)planet particle and radiation field with the (exo)planetary atmosphere, was used to revisit the modeling of the altitude-dependent Venusian atmospheric ionization. Thereby, spherical geometry, the newest version of Geant4 (10.5) as well as the newest Geant4-based hadronic and electromagnetic interaction models were utilized.

Results.Based on our new model approach we show that previous studies may have underestimated the galactic cosmic ray-induced atmospheric ion pair production by, amongst others, underestimating the influence of galactic cosmic ray protons above 1 TeV/nuc. Furthermore, we study the influence of 71 exceptionally strong solar particle events that were measured as Ground Level Enhancements at the Earth’s surface, and show a detailed analysis of the impact of such strong events on the Venusian ionization.
Viability analysis of the first-order mean field games
Authors: Averboukh Yurii
Published: March 2019

In the paper, we examine the dependence of the solution of the deterministic mean field game on the initial distribution of players. The main object of study is the mapping which assigns to the initial time and the initial distribution of players the set of expected rewards of the representative player corresponding to solutions of mean field game. This mapping can be regarded as a value multifunction. We obtain the sufficient condition for a multifunction to be a value multifunction. It states that if a multifunction is viable with respect to the dynamics generated by the original mean field game, then it is a value multifunction. Furthermore, the infinitesimal variant of this condition is derived.
Verbreitung und Ätiologie von kraniomandibulären Dysfunktionen (CMD) im Kindes- und Jugendalter
Authors: Hirsch Christian
Published: March 2019

Kinder und Jugendliche sind in der zahnärztlichen Sprechstunde als CMD‑Patienten kaum anzutreffen, obwohl die Symptome bereits in diesem Alter weitverbreitet sind. Das Erstauftreten von CMD besonders bei Mädchen während der Pubertät sowie die höhere Prävalenz bei Frauen während des Reproduktionsalters lassen die hormonellen Umstellungen während der Pubertät als ätiopathogenetisch bedeutsam erscheinen. Die Mechanismen sind noch nicht klar, es scheint aber ein Mangel an frei verfügbaren Sexualhormonen während der Pubertät ausschlaggebend zu sein. Hierbei könnte es sich um ein grundlegendes Muster für viele unklare Schmerzsymptome handeln, da damit klinische Beobachtungen erklärt werden können: der typische Alters- und Geschlechtsverlauf von CMD, die psychosoziale Charakteristik von CMD-Schmerzpatienten sowie die hohe Koinzidenz der verschiedenen Schmerzarten. Dagegen spielen morphologische Faktoren und deren Veränderungen, z. B. infolge kieferorthopädischer Behandlungen, in der Ätiologie von CMD während des Jugendalters kaum eine Rolle. Darüber hinaus gibt es Erkenntnisse über genetische Ursachen der CMD, ein Bereich, der ebenfalls Gegenstand aktueller Forschungen ist.
Pharmacokinetic Profile of Curcumin and Nanocurcumin in Plasma, Ovary, and Other Tissues
Authors: Arozal Wawaimuli , Ramadanty Wenny Trias , Louisa Melva , Satyana Regina Puspa Utami , Hartono Gaviota , Fatrin Serlie , Purbadi Sigit , Estuningtyas Ari , Instiaty Instiaty
Published: March 2019

Background Curcumin is a natural diphenolic compound that is currently being investigated for various cancers, including ovarian cancer. Clinical application of curcumin has been limited due to its low solubility and bioavailability and rapid metabolism and degradation at physiological pH. Particle size is one factor that can affect the absorption process, which thus increases compound solubility and transport across the membrane. This study was conducted to determine the effects of modifying the particle size of curcumin on its pharmacokinetic parameters in blood and other organs.

Methods Female Sprague Dawley rats were administered a single oral dose of 500 mg/kg curcumin or nanocurcumin. Blood samples were collected at 10, 15, 30, 45, 75, and 120 min, and ovaries, livers, kidneys, and colons were collected at 180 min. The levels of curcumin in plasma and organs were determined using UPLC-MS/MS, and the pharmacokinetic parameters were evaluated.

Results Curcumin levels were detectable and measurable in plasma and organs of rats that were administered curcumin or nanocurcumin. Overall, no statistically significant differences were found in pharmacokinetic parameters between curcumin and nanocurcumin groups in both plasma and organs, except for ovaries. The curcumin levels in plasma, liver, kidney, and colon in the curcumin group were higher than those in the nanocurcumin group. However, curcumin concentrations in ovaries in the nanocurcumin group were 3.6 times higher than those in the curcumin group.

Conclusion Particle size reduction of curcumin did not increase the concentration of curcumin in the plasma but increased its distribution in the ovaries.
Potassium Alkoxide/Disilane-Mediated Dehalogenative Deuteration
Authors: Wang Xin , Zhu Ming-Hui , Liu Wen-Bo
Published: March 2019

Deuterated compounds are of great importance in chemistry and pharmaceuticals. Reductive dehalogenation is one of the most useful methods to incorporate deuterium into molecules. This article briefly discusses the historical development of dehalogenative deuteration reactions that involve transition-metal catalysis, radical halogen abstraction, alkali-metal reductive deuteration, and the recently developed potassium methoxide/hexamethyldisilane-mediated dehalogenation of aryl halides.
A One-Pot Sonogashira Coupling and Annulation Reaction: An Efficient Route toward 4H-Quinolizin-4-ones
Authors: Chen Zhengwang , Liu Tanggao , Ma Xiaoyue , Liang Pei , Long Lipeng , Ye Min
Published: March 2019

An efficient one-pot Sonogashira coupling and annulation reaction affording 4H-quinolizin-4-ones in moderate to excellent yields is described. A variety of substituted iodoarenes and 2-alkylazaarenes were well tolerated, and especially the unsaturated double and triple bonds were compatible under the standard conditions.
Biocatalytic Synthesis of α-Amino Ketones
Authors: Chun Stephanie W. , Narayan Alison R. H.
Published: March 2019

Stereospecific generation of α-amino ketones from common α-amino acids is difficult to achieve, often employing superstoichiometric alkylating reagents and requiring multiple protecting group manipulations. In contrast, the α-oxoamine synthase protein family performs this transformation stereospecifically in a single step without the need for protecting groups. Herein, we detail the characterization of the 8-amino-7-oxononanoate synthase (AONS) domain of the four-domain polyketide-like synthase SxtA, which natively mediates the formation of the ethyl ketone derivative of arginine. The function of each of the four domains is elucidated, leading to a revised proposal for the initiation of saxitoxin biosynthesis, a potent neurotoxin. We also demonstrate the synthetic potential of SxtA AONS, which is applied to the synthesis of a panel of novel α-amino ketones.

1 Introduction

2 Native SxtA Module Activity

3 New Reactions with SxtA AONS

4 Conclusions and Outlook
Halotrimethylsilane-Nitrite/Nitrate Salts: Efficient and Versatile Reagent System for Diverse Organic Synthetic Transformations
Authors: Mathew Thomas , Gurung Laxman , Roshandel Sahar , Munoz Socrates , Prakash G.
Published: March 2019

The reagent system comprised of halotrimethylsilane and nitrite or nitrate salts has now been successfully used as an efficient system for a series of versatile synthetic transformations. In recent years, the significance and efficacy of this system for reactions such as nitration of aromatics and olefins, oxidation of thiols to sulfonyl chlorides, ipso-nitrosation/nitration of arylboronic acids, ipso-nitration of α,β-unsaturated carboxylic acids to nitro olefins, etc. have been disclosed. Though the reagent system has not been exploited to its full potential, the reported reactions reveal its advantages as a very safe and convenient system that works under mild conditions. This brief Account reveals various synthetic applications of halotrimethylsilane-nitrite/nitrate salts in organic synthesis hitherto reported.

1 Introduction

2 Reactions Using a Halotrimethylsilane-Nitrate Salt System

2.1 Nitration of Olefins and Aromatics

2.2 One-Pot Preparation of gem-Chloronitroso, gem-Chloronitro, and vic-Dichloro Compounds

2.3 One-Step Conversion of Anilines into Haloarenes

2.4 Deoximation of Aldoximes to Aldehydes and Ketoximes to ­Ketones

2.5 One-Pot Synthesis of Cyclic/Noncyclic α-Nitroketones from ­Cyclic/Noncyclic Olefins

2.6 ipso-Nitration of Arylboronic Acids

2.7
ipso-Nitrosation of Arylboronic Acids

2.8 Oxidation of Sulfides and Sulfoxides to Sulfones

2.9 Oxidative Chlorination of Thiols and Disulfides to Sulfonyl ­Chlorides

2.10

α-Halogenation of Carbonyl Compounds

2.11 Decarboxylative ipso-Nitration and Dibromination of Cinnamic Acid

3 Conclusion
Catalytic Carboxylation of Heteroaromatic Compounds: Double and Single Carboxylation with CO2
Authors: Mita Tsuyoshi , Masutani Hiroki , Ishii Sho , Sato Yoshihiro
Published: March 2019

In the presence of PdCl2[P(n-Bu)3]2 (10 mol%) and ZnEt2, 2-furyl and 2-pyrrolylmethyl acetate were carboxylated with CO2 (1 atm), affording doubly carboxylated products in good yields. In this dearomative transformation, α,ε-dicarboxylic acids were obtained selectively, in contrast to our previous report in which α,γ-dicarboxylic acids were selectively produced from 2-indolylmethyl acetates. In contrast, 5-thiazolylmethyl acetate and naphthylmethyl acetates predominantly underwent single carboxylation.
Indications for General versus Local Anesthesia during Carotid Endarterectomy
Authors: Mracek Jan , Kletecka Jakub , Mork Jan , Stepanek David , Dostal Jiri , Mrackova Jolana , Priban Vladimir
Published: March 2019

Background and Study Aims Both general anesthesia (GA) and local anesthesia (LA) are used in our department for carotid endarterectomy. The decision of which anesthetic technique to use during surgery is made on an individual basis. The aim of our study was to analyze the reasons for using GA or LA.

Material and Methods The reasons that led to the selection of either GA or LA were analyzed retrospectively in a group of 409 patients.

Results GA was used in 304 patients (74%) and LA in 105 patients (26%). The reasons for a preference for GA were clopidogrel use (88 patients), patient preference (80), increased risk of shunt insertion (43), unfavorable anatomical conditions (41), surgeon preference (21), simultaneous carotid endarterectomy and cardiac surgery (18), emergent carotid endarterectomy (12), and sleep apnea syndrome (1). The reasons for selecting LA were internal comorbidities (46 patients), patient preference (39), unavailability of intraoperative electrophysiologic monitoring (15), and pacemaker (5).

Conclusion GA is the dominant choice for carotid endarterectomy in our department because of its prevailing benefits and its preference among neurosurgeons and patients. However, in some subgroups of patients, LA is preferable. An optimal approach is therefore an individual indication for both anesthesia techniques.
Hepatic Artery Pseudoaneurysm Rupture with Acute Portal Vein Occlusion Treated with Coronary Stent Graft and Trans-splenic Portal Vein Stenting
Authors: Allison Stephen , Jeyakumar Arthie , Johnson Guy , Kogut Matthew
Published: March 2019

Delayed massive hemorrhage following pancreaticoduodenectomy is a potentially fatal condition. These patients are often not surgical candidates, and endovascular therapy is the primary option of treatment, usually trans-arterial embolization. However, the bleeding vessel can occasionally be treated with a stent graft rather than embolization. This decreases the risk of hepatic necrosis by preserving hepatic arterial blood flow, particularly in patients with compromised portal veins. The authors present a brief case report of delayed pseudoaneurysm rupture from a replaced proper hepatic artery after pancreaticoduodenectomy with resultant portal vein occlusion, caused by hematoma mass effect. The hepatic artery was treated with a coronary stent. During the same session, trans-splenic portal vein stenting was done.
Carpal Translocation Following Dorsal Bridge Plate Fixation of Distal Radius Fractures: A Cadaveric Study
Authors: Azad Ali , Intravia Jessica M. , Hill J. Ryan , Leland Hyuma , Vakhshori Venus , Stevanovic Milan , Ghiassi Alidad
Published: March 2019

Background Dorsal bridge plate fixation is an effective technique for stabilization of highly comminuted, complex distal radius fractures. However, it is unknown whether fixation to the second or third metacarpal is optimal. Given dorsal bridge plating spans the radiocarpal joint, it is unclear if the dorsal spanning plate affects carpal position. This study investigates differences in carpal translocation resulting from bridge plate distal fixation to either the second or third metacarpal.

Methods Ten paired cadaveric upper extremities without evidence of gross deformity or prior surgery distal to the elbow were evaluated with three-view wrist fluoroscopic images for baseline radiographic measurements. An unstable distal radius fracture model was created via a volar approach using a 1-cm osteotomy. Following fracture creation, a dorsal bridge plate was applied with random to the second metacarpal on one limb, and the third metacarpal on the contralateral limb. Laterality for distal fixation was chosen randomly. Fluoroscopic images were repeated and radial inclination, radial height, radiocarpal angle, volar tilt, ulnar variance, radiolunate angle, radioscaphoid angle, radial rotation index, and carpal translocation were measured.

Results Radial inclination, radial height, radiocarpal angle, volar tilt, ulnar variance, radiolunate angle, and radioscaphoid angle were not statistically different before and after fixation, or when comparing the second or third metacarpal fixation. Additionally, there was no difference in Taleisnik's ulnar translocation index, Chamay's ulnar translation index, or McMurtry's carpal translation index based on which metacarpal was used for distal fixation.

Conclusions Dorsal bridge plate fixation of distal radius fractures restores preoperative physiologic measures of the radius, ulna, and carpus. Carpal translocation was similar when comparing distal fixation to the second or third metacarpal in distal radius fractures stabilized with a bridge plate.

Level of Evidence This is a Level V, therapeutic study.
Suppression of molybdenum impurity accumulation in the core using on-axis electron cyclotron resonance heating in EAST
Authors: Shen Yongcai , Lyu Bo , Zhang Hongming , Li Yingying , Fu Jia , Vogel German , Wang Xiaojie , Xu Handong , Wu Dajun , Zang Qing , Liu Haiqing , Liu Fukun , Wan Baonian , Ye Minyou
Published: March 2019

Core metal impurity transport in an electron cyclotron resonance heating (ECRH) plasma is investigated for the first time in experimental advanced superconducting tokamak, on the basis of profile measurements of impurity emissions using space-resolved extreme ultraviolet spectroscopy. A significant reduction in the core molybdenum emissivity is observed during the on-axis ECRH phase, accompanied by decreased core electron density and increased electron temperature. The impurity transport study before and during ECRH injection is performed using line emissions of Mo XXIX, Mo XXX, Mo XXXI, and Mo XXXII with the core impurity transport code, STRAHL. It is found that the diffusion coefficient increases substantially and that the value of the diffusion coefficient is about one order of magnitude higher than that of neoclassical transport. Also, the inward convective velocity decreases and even changes its direction in the core region (ρ < 0.5) during on-axis ECRH, which is thought to dominantly contribute to the reduction in core impurity ion density.
Extrusion bioprinting of soft materials: An emerging technique for biological model fabrication
Authors: Jiang Tao , Munguia-Lopez Jose G. , Flores-Torres Salvador , Kort-Mascort Jacqueline , Kinsella Joseph M.
Published: March 2019

Bioprinting has attracted increasing attention in the tissue engineering field and has been touted to potentially become the leading technology to fabricate, and regenerate, tissues and organs. Bioprinting is derived from well-known additive manufacturing (AM) technology, which features layered deposition of materials into complex three-dimensional geometries that are difficult to fabricate using conventional manufacturing methods. Unlike the conventional thermoplastics used in desktop, AM bioprinting uses cell-laden hydrogel materials, also known as bioinks, to construct complex living biological model systems. Inkjet, stereolithography, laser-induced forward transfer, and extrusion are the four main methods in bioprinting, with extrusion being the most commonly used. In extrusion-based bioprinting, soft materials are loaded into the cartridges and extruded from the nozzle via pneumatic or mechanical actuation. Multiple materials can be printed into the same structure resulting in heterogeneous models. In this focused review, we first review the different methods to describe the physical mechanisms of the extrusion process, followed by the commonly employed bioprintable soft materials with their mechanical and biochemical properties and finally reviewing the up-to-date heterogeneous in vitro models afforded via bioprinting.
Left-handed band in an electromagnetic metamaterial induced by sub-wavelength multiple scattering
Authors: Yves Simon , Berthelot Thomas , Fink Mathias , Lerosey Geoffroy , Lemoult Fabrice
Published: March 2019

Due to the deep sub-wavelength unit cell in metamaterials, the quasi-static approximation is usually employed to describe the propagation. By making pairs of resonators, we highlight that multiple scattering also occurs at this scale and results in the existence of a dipolar resonance, which leads to a negative index of refraction when we consider several resonators. We experimentally verify the possibility of obtaining a negative index of refraction in periodic metamaterials in two different ways and eventually demonstrate the subwavelength recovery of several point sources in both cases.
Global model of microwave plasma assisted N2O dissociation for monopropellant propulsion
Authors: Bosi Franco Javier
Published: March 2019

A global numerical model is developed to study the capability of a Microwave Electro-thermal thruster (MET) to operate with Nitrous Oxide gas (N2O), for spacecraft monopropellant thruster applications. N2O is a “green” propellant with interesting properties but highly inert when used as monopropellant; the non-equilibrium activation effect of the plasma is able to promote combustion of the gas. The model is self-consistent and features different temperatures for the vibrational modes of the mixture in order to account for possible vibrational activation effects of the plasma; a detailed kinetic scheme is presented, comprising rates for vibrational energy exchanges between the modes. The model shows that good theoretical efficiencies can be achieved by operating the MET with N2O, with thrust to power ratios up to 1 mN/W and specific impulse up to 200 s. The main channels of plasma assisted dissociation are examined, and the role of vibrational non-equilibrium is addressed.
Design of high-performance Au-Ag-dielectric-graphene based surface plasmon resonance biosensors using genetic algorithm
Authors: Lin Chengyou , Chen Shujing
Published: March 2019

In this paper, we presented a design method of a surface plasmon resonance (SPR) biosensor with high performance using a genetic algorithm (GA). The constraint conditions of the sensitivity and the reflectivity at the resonance angle were used in the merit function (MF) of GA to achieve simultaneous optimization of the sensitivity and the resolution. By using the proposed method, we designed an Au-Ag-TiO2-graphene based SPR biosensor at first and compared its performance with a traditional Au-graphene based SPR biosensor. The resolution of the designed biosensor was nearly three times that of the traditional one on the premise of the same sensitivity. In addition, a series of SPR biosensors with sensitivities ranging from 50 to 180°/RIU and improved resolutions was designed by using different target sensitivities in MF. A comparison of the designed biosensors with the traditional Au-graphene SPR biosensor was also done, and the biosensors with higher sensitivity and meanwhile higher resolution than the traditional one were demonstrated to be existed. Lastly, the influences of target reflectivity at the resonance angle and the prism on the design of the Au-Ag-TiO2-graphene based SPR biosensor were investigated. It is believed that the proposed design method based on the genetic algorithm could be applied to optimize the performances of a SPR biosensor with an arbitrary multilayer structure.
Photoemissive properties and stability of undecylenic acid-modified porous silicon nanoparticles in physiological medium
Authors: Schiattarella Chiara , Terracciano Monica , Defforge Thomas , Gautier Gaël , Ventura Bartolomeo Della , Moretta Rosalba , De Stefano Luca , Velotta Raffaele , Rea Ilaria
Published: March 2019

Porous silicon nanoparticles (PSiNPs) are non-toxic photoluminescence imaging agents whose potential for biophotonic applications has been widely reported in recent years. However, this material suffers from intrinsic limitations, due to its chemical instability and rapid photoluminescence extinction on exposure to the physiological environment. In this letter, a mild functionalization procedure for PSiNP stabilization, based on undecylenic acid conjugation via hydrosilylation, is proven to be effective under simulated biological conditions [phosphate-buffered saline (PBS) 0.1 M, pH = 7.4]. Once stored in isopropanol, bare and hydrosilylated PSiNPs (h·PSiNPs) show similar photoemissive properties: photoluminescence quantum yield (>10%), steady-state spectra, and emission lifetime. Interestingly, the behaviour of these nanoparticles is completely different in the physiological medium: the morphology and the photoluminescence emission of bare PSiNPs completely degrade within 2 h, whereas a full preservation of the same features up to 6 h is demonstrated for h·PSiNPs.
Exact solutions of Schrödinger and Pauli equations for a charged particle on a sphere and interacting with non-central potentials
Authors: Oliveira M. D. , Schmidt Alexandre G. M.
Published: March 2019

We calculate exact solutions of the Schrödinger equation for a particle constrained to move along a spherical surface and interacting with non-central potentials, namely, (i) Makarov, (ii) ring-shaped pseudo-harmonic oscillatory, and (iii) Kratzer potentials. We also study exact solutions of the Pauli equation in the same geometrical setting for a charged particle in the presence of a uniform magnetic field. In this case, the two-component spinor can adhere to the surface only if the magnetic field intensity has certain special values. The solutions of Schrödinger equations allow us to obtain exact Pauli spinors and their corresponding energy eigenvalues for the same non-central potentials.
Magnetic and structural properties of L1-Mn50Ga50-xAlx epitaxially grown thin films
Authors: Kamiya Keisuke , Zhao Siqian , Tanaka Yoshitomo , Mankey Gary , Suzuki Takao
Published: March 2019

Epitaxially grown L10- MnGa(Al) continuous thin films with the c-axis along the film normal are successfully fabricated on MgO (001) substrates at a substrate deposition temperature Ts of around 400 °C. The order parameter S is found to decrease with Al content, except for that for Al = 0. The films under consideration exhibit the perpendicular magnetic anisotropy constant Ku of about 1 x 107 erg/cm3 at 300 K. In order to clarify the magnetic anisotropy mechanism, the correlation between Ms(T) and Ku(T) is discussed. It is found that the values of n in the power law relation Ku(T) ∼ Ms(T)n are found to be 2.6, 2.3, and 2.0 for the films of 2.5, 5.6, 11.2 Al at%, respectively. The present result suggests that the magnetic anisotropy of L10-MnGaAl thin films may be explained in terms of the two-ion model, where both the contributions of Mn and Ga are significant to the total magnetic anisotropy”. The decrease of the value n with Al addition n is of interest, but the reason for this change is not understood at present.
Temperature dependence of magnetic first-order-reversal-curves for hollow Fe3O4 submicron particles
Authors: Chiba Momoko , Kobayashi Satoru , Murakami Takeshi , Manjanna Jayappa , Szpunar Jerzy A.
Published: March 2019

We report results of temperature dependence of first-order-reversal curves (FORCs) for hollow submicron particles with different outer diameter ranging from 400 to 700 nm. At low temperatures below the Verwey transition temperature, Tv, the FORC distribution exhibits a butterfly-like feature, associated with two pronounced FORC peaks, indicating the formation of a vortex structure for hollow Fe3O4 submicron particles. With increasing temperature from T = 10 K, the intensity of the two peaks steeply decreases and the peaks merge at T ∼ 130 K close to Tv. The results suggest a change of stability of the vortex state with temperature and were explained as due to a change of magnetic anisotropy associated with a structural transition at Tv.
Modeling inter-particle magnetic correlations in magnetite nanoparticle assemblies using x-ray magnetic scattering data
Authors: Rackham Johnathon , Newbold Brittni , Kotter Steve , Smith Dallin , Griner Dalton , Harrison Roger , Reid Alex H. , Transtrum Mark , Chesnel Karine
Published: March 2019

Magnetic nanoparticles are increasingly used in nanotechnologies and biomedical applications, such as drug targeting, MRI, bio-separation. Magnetite (Fe3O4) nanoparticles stand to be effective in these roles due to the non-toxic nature of magnetite and its ease of manufacture. To be more effective in these applications, a greater understanding of the magnetic behavior of a collection of magnetite nanoparticles is needed. This research seeks to discover the local magnetic ordering of ensembles of magnetite nanoparticles occurring under various external fields. To complete this study, we use x-ray resonant magnetic scattering (XRMS). Here we discuss the modeling of the magnetic scattering data using a one-dimensional chain of nanoparticles with a mix of ferromagnetic, anti-ferromagnetic, and random orders. By fitting the model to the experimental data, we extracted information about the magnetic correlations in the nanoparticle assembly.
Temperature-dependent photo-response in multiferroic BiFeO3 revealed by transmission measurements
Authors: Meggle F. , Viret M. , Kreisel J. , Kuntscher C. A.
Published: March 2019

We studied the light-induced effects in BiFeO3 single crystals as a function of temperature by means of optical spectroscopy. Here, we report the observation of several light-induced absorption features, which are discussed in terms of the photostriction effect and are interpreted in terms of excitons. The temperature dependence of their energy position suggests a possible coupling between the excitons and the lattice vibrations. Moreover, there are hints for anomalies in the temperature evolution of the excitonic features, which might be related to the temperature-induced magnetic phase transitions in BiFeO3. Our findings suggest a coupling between light-induced excitons and the lattice and spin degrees of freedom, which might be relevant for the observed ultrafast photostriction effect in multiferroic BiFeO3.
On a new class of score functions to estimate tail probabilities of some stochastic processes with adaptive multilevel splitting
Authors: Bréhier Charles-Edouard , Lelièvre Tony
Published: March 2019

We investigate the application of the adaptive multilevel splitting algorithm for the estimation of tail probabilities of solutions of stochastic differential equations evaluated at a given time and of associated temporal averages. We introduce a new, very general, and effective family of score functions that is designed for these problems. We illustrate its behavior in a series of numerical experiments. In particular, we demonstrate how it can be used to estimate large deviations rate functionals for the longtime limit of temporal averages.
Colloidal Brazil nut effect in microswimmer mixtures induced by motility contrast
Authors: Jahanshahi Soudeh , Lozano Celia , ten Hagen Borge , Bechinger Clemens , Löwen Hartmut
Published: March 2019

We numerically and experimentally study the segregation dynamics in a binary mixture of microswimmers which move on a two-dimensional substrate in a static periodic triangular-like light intensity field. The motility of the active particles is proportional to the imposed light intensity, and they possess a motility contrast, i.e., the prefactor depends on the species. In addition, the active particles also experience a torque aligning their motion towards the direction of the negative intensity gradient. We find a segregation of active particles near the intensity minima where typically one species is localized close to the minimum and the other one is centered around in an outer shell. For a very strong aligning torque, there is an exact mapping onto an equilibrium system in an effective external potential that is minimal at the intensity minima. This external potential is similar to (height-dependent) gravity such that one can define effective “heaviness” of the self-propelled particles. In analogy to shaken granular matter in gravity, we define a “colloidal Brazil nut effect” if the heavier particles are floating on top of the lighter ones. Using extensive Brownian dynamics simulations, we identify system parameters for the active colloidal Brazil nut effect to occur and explain it based on a generalized Archimedes’ principle within the effective equilibrium model: heavy particles are levitated in a dense fluid of lighter particles if their effective mass density is lower than that of the surrounding fluid. We also perform real-space experiments on light-activated self-propelled colloidal mixtures which confirm the theoretical predictions.
Electric field control of magnetism in Si3N4 gated Pt/Co/Pt heterostructures
Authors: Vijayakumar Jaianth , Bracher David , Savchenko Tatiana M. , Horisberger Michael , Nolting Frithjof , Vaz C. A. F.
Published: March 2019

In this work, we show the presence of a magnetoelectric coupling in silicon-nitride gated Pt/Co/Pt heterostructures using X-ray photoemission electron microscopy. We observe a change in magnetic anisotropy in the form of domain wall nucleation and a change in the rate of domain wall fluctuation as a function of the applied electric field to the sample. We also observe the coexistence of in-plane and out-of-plane magnetization in Pt/Co/Pt heterostructures in a region around the spin reorientation transition whose formation is attributed to substrate surface roughness comparable to the film thickness; with such domain configuration, we find that the in-plane magnetization is more sensitive to the applied electric field than out-of-plane magnetization. Although we find an effective magnetoelectric coupling in our system, the presence of charge defects in the silicon nitride membranes hampers the systematic electrostatic control of the magnetization.
Strain-induced resistance change in V2O3 films on piezoelectric ceramic disks
Authors: Sakai Joe , Bavencoffe Maxime , Negulescu Beatrice , Limelette Patrice , Wolfman Jérôme , Tateyama Akinori , Funakubo Hiroshi
Published: March 2019

We prepared a stacked structure consisting of a quasi-free-standing functional oxide thin film and a ceramic piezoelectric disk and observed the effect of the piezoelectric disk deformation on the resistance of the thin film. Epitaxial V2O3 films were grown by a pulsed laser deposition method on muscovite mica substrates, peeled off using Scotch tapes, and transferred onto piezoelectric elements. In this V2O3/insulator/top electrode/piezoelectronic disk/bottom electrode structure, the resistance of the V2O3 film displayed a variation of 60% by sweeping the piezoelectronic disk bias. With support from x-ray diffraction measurements under an electric field, a huge gauge factor of 3 × 103 in the V2O3 film was inferred. The sizeable resistance change in the V2O3 layer is ascribed to the piezo-actuated evolution of c/a ratios, which drives the material towards an insulating phase. A memory effect on the resistance, related to the hysteretic displacement of the piezoelectric material, is also presented.
Thermal transport at a nanoparticle-water interface: A molecular dynamics and continuum modeling study
Authors: Rajabpour Ali , Seif Roham , Arabha Saeed , Heyhat Mohammad Mahdi , Merabia Samy , Hassanali Ali
Published: March 2019

Heat transfer between a silver nanoparticle and surrounding water has been studied using molecular dynamics (MD) simulations. The thermal conductance (Kapitza conductance) at the interface between a nanoparticle and surrounding water has been calculated using four different approaches: transient with/without temperature gradient (internal thermal resistance) in the nanoparticle, steady-state non-equilibrium, and finally equilibrium simulations. The results of steady-state non-equilibrium and equilibrium are in agreement but differ from the transient approach results. MD simulation results also reveal that in the quenching process of a hot silver nanoparticle, heat dissipates into the solvent over a length-scale of ∼2 nm and over a time scale of less than 5 ps. By introducing a continuum solid-like model and considering a heat conduction mechanism in water, it is observed that the results of the temperature distribution for water shells around the nanoparticle agree well with the MD results. It is also found that the local water thermal conductivity around the nanoparticle is greater by about 50% than that of bulk water. These results have important implications for understanding heat transfer mechanisms in nanofluid systems and also for cancer photothermal therapy, wherein an accurate local description of heat transfer in an aqueous environment is crucial.
Polymer nucleation under high-driving force, long-chain conditions: Heat release and the separation of time scales
Authors: Hall Kyle Wm. , Percec Simona , Klein Michael L.
Published: March 2019

This study reveals important features of polymer crystal formation at high-driving forces in entangled polymer melts based on simulations of polyethylene. First and in contrast to small-molecule crystallization, the heat released during polymer crystallization does not appreciably influence structural details of early-stage, crystalline clusters (crystal nuclei). Second, early-stage polymer crystallization (crystal nucleation) can occur without substantial chain-level relaxation and conformational changes. This study’s results indicate that local structures and environments guide crystal nucleation in entangled polymer melts under high-driving force conditions. Given that such conditions are often used to process polyethylene, local structures and the separation of time scales associated with crystallization and chain-level processes are anticipated to be of substantial importance to processing strategies. This study highlights new research directions for understanding polymer crystallization.
Third-order optical nonlinearity in silicon nitride films prepared using magnetron sputtering and application for optical bistability
Authors: Ding Baoyong , Yu Xiuru , Lu Heng , Xiu Xianwu , Zhang Chao , Yang Cheng , Jiang Shouzhen , Man Baoyuan , Ning Tingyin , Huo Yanyan
Published: March 2019

We investigate the third-order optical nonlinearity in silicon nitride (SiN) films prepared using magnetron sputtering. The large nonlinear refractive index n2 in SiN prepared at room temperature of a value of −2.00 × 10−16 m2/W and the nonlinear absorption coefficient β of 1.44 × 10−9 m/W are determined by the Z-scan method at a wavelength of 1064 nm and a pulse duration of 25 ps. The n2 is three orders of magnitude larger than that in SiN films prepared by the chemical vapor deposition method and at a wavelength of 1.55 μm. The enhanced n2 up to −6.27 × 10−16 m2/W and the slightly changed β, indicating an enhanced ratio of |Reχ(3)|/|Imχ(3)|, are further obtained in the annealed samples. Such a change is probably due to the crystallization of the films. The optical bistability in SiN resonant waveguide grating (RWG) is numerically studied. The low threshold intensity around 300 MW/cm2 in the RWG is obtained.
Coexistence of dielectric relaxation and magnetic relaxation in compressively strained BiFeO3/Ba0.7Sr0.3TiO3 superlattices
Authors: Miao J. , Chew K.-H. , Zhang L. X. , Wu R. , Wang J. O. , Shao F. , Zhan Q. , Jiang Y.
Published: March 2019

Superlattices (SLs) consisting of multiferroic BiFeO3 (BFO) and dielectric Ba0.7Sr0.3TiO3 were epitaxially grown on a (001)-oriented Nb:SrTiO3 substrate using pulsed laser deposition. An improved ferroelectricity with a high-temperature polarization of ∼63.7 μC/cm2 at 470 K was observed. The SL exhibited both dielectric and magnetic relaxation properties. Two distinct dielectric relaxations were found: a carrier hopping process between Fe2+ and Fe3+ from 273 to 410 K and the long-range migration of oxygen vacancies from 430 to 573 K. Spin-glass behavior with a freezing temperature of ∼86.6 K was also observed. This work provides a promising path forward to tailor the multiferroic properties of BFO-based structures for high-temperature applications.
Full characterization of electronic transport properties in working polymer light-emitting diodes via impedance spectroscopy
Authors: Takada Makoto , Nagase Takashi , Kobayashi Takashi , Naito Hiroyoshi
Published: March 2019

The electron and hole drift mobilities of organic semiconductor layers, localized tail state distributions, and bimolecular recombination constants in working polymer light-emitting diodes (PLEDs) are determined simultaneously using impedance spectroscopy (IS). The organic light-emitting layers of these PLEDs are composed of poly(9,9-dioctylfluorene-alt-benzothiadiazole). Electron and hole transit time effects are observed in the capacitance-frequency characteristics of the PLEDs, and their drift mobilities are determined over wide temperature and electric field ranges. The drift mobilities exhibit thermally activated behavior, and the localized tail state distributions from the conduction band and valence band mobility edges are then determined from analysis of the electric field dependences of the activation energies. The bimolecular recombination constants are determined from the inductive response of the impedance-frequency characteristics. The IS technique is also applicable to degradation analysis of the PLEDs; changes in the mobility balance, the localized tail state distributions, and the bimolecular recombination constant caused by aging are all shown.
An innovative experimental equipment for liquid nitrogen fracturing
Authors: Huang Pengpeng , Huang Zhongwei , Yang Zheqi , Wu Xiaoguang , Li Ran , Zhang Shikun
Published: March 2019

Due to the unique physical and chemical properties of liquid nitrogen (LN2), LN2 fracturing has been considered as a promising reservoir stimulation technique. In order to further investigate the feasibility of LN2 fracturing, a new device is designed to research the effect of LN2 fracturing under different conditions, such as different specimen sizes, temperatures, and confining pressures. The setup consists of three units: a high-pressure LN2 generating system, a true-triaxial loading and heating system, and a control and data acquisition system. Now, a series of experiments have been successfully carried out based on the setup. The results have proven the excellent fracturing effect of LN2 and the applications of this setup. The apparatus lays a foundation for the application of LN2 fracturing in both conventional and geothermal reservoirs.