bluuebunny/crossref_metadata_2025 huggingface dataset:
An interface-targeting and H2O2-activatable probe liberating AIEgen: enabling on-site imaging and dynamic movement tracking of lipid droplets
Authors: Li Wenting , Wang Lingyun , Tang Hao , Cao Derong
Published: March 2019

An efficient LD imaging assay method with high selectivity and sensitivity by an interface-targeting and H2O2-activatable probe liberating AIEgen is developed.
Dual copper- and photoredox-catalysed C(sp2)–C(sp3) coupling
Authors: McLean Euan B. , Gauchot Vincent , Brunen Sebastian , Burns David J. , Lee Ai-Lan
Published: March 2019

The use of copper catalysis with visible light photoredox catalysis in a cooperative fashion has recently emerged as a versatile means of developing new C–C bond forming reactions. In this work, dual copper and photoredox catalysis is exploited to effect C(sp2)–C(sp3) cross-couplings between aryl boronic acids and benzyl bromides.
Cholesterol-based photo-switchable mesogenic dimers. Strongly bent molecules versus an intercalated structure
Authors: Zep Anna , Pruszkowska Kamila , Dobrzycki Łukasz , Sektas Katarzyna , Szałański Piotr , Marek Paulina H. , Cyrański Michał K. , Sicinski Rafal R.
Published: March 2019

A homologous series of cholesterol-based liquid crystalline dimers were synthesized and characterized by polarizing optical microscopy, DSC, and powder and single-crystal XRD.
The relationship between the asymmetric magnetoresistive effect and the magnetocaloric effect in Ni43Co7Mn39−xCrxSn11 Heusler alloys
Authors: Xu Yunli , Yang Dongchao , Ding Linjie , Yi Lizhi , Fan Shuaiwei , Pan Liqing , Li Jia , Hu Fengxia , Yu Guanghua , Xiao John Q.
Published: March 2019

The correlation between the magnetocaloric effect and magnetotransport property was investigated in Ni43Co7Mn39−xCrxSn11 Heusler alloys.
Customizing topographical templates for aperiodic nanostructures of block copolymers via inverse design
Authors: Zhang Runrong , Zhang Liangshun , Lin Jiaping , Lin Shaoliang
Published: March 2019

We integrated an advanced inverse search algorithm with a polymeric theoretical model to customize topographical templates for the reproduction of target structures over exceptionally large areas.
Recent advances and prospects in nickel-catalyzed C–H activation
Authors: Harry Nissy Ann , Saranya Salim , Ujwaldev Sankuviruthiyil M. , Anilkumar Gopinathan
Published: March 2019

Nickel-catalyzed C–H activation has become a predominant and ubiquitous research area in organic chemistry.
Comparative study on the phytochemical profiles and cellular antioxidant activity of phenolics extracted from barley malts processed under different roasting temperatures
Authors: Chen Yongsheng , Huang Junqing , Hu Jing , Yan Rian , Ma Xiang
Published: March 2019

Consumption of cereal foods has been related to health improvement, which is partly because of their phytochemicals.
Expedient preparation of active pharmaceutical ingredient ketamine under sustainable continuous flow conditions
Authors: Kassin Victor-Emmanuel H. , Gérardy Romaric , Toupy Thomas , Collin Diégo , Salvadeo Elena , Toussaint François , Van Hecke Kristof , Monbaliu Jean-Christophe M.
Published: March 2019

Continuous flow preparation of antidepressant ketamine and analogs under sustainable conditions.
Designing molecular building blocks for the self-assembly of complex porous networks
Authors: Maula T. Ann , Hatch Harold W. , Shen Vincent K. , Rangarajan Srinivas , Mittal Jeetain
Published: March 2019

We leverage building block geometry and intermolecular interactions to facilitate self-assembly into ordered, heteroporous networks.
Gadolinium-containing polymer microspheres: a dual-functional theranostic agent for magnetic resonance imaging and cancer therapy
Authors: Dong Xu , Tahir Muhammad Ali , Zhang Liwu , Schäfer Christian G.
Published: March 2019

Preparation of poly(gadolinium methacrylate-co-methacrylic acid) copolymer microspheres with high MRI contrast efficiency and controlled anti-cancer drug loading and release capability.
Type of complex–BSA binding forces affected by different coordination modes of alliin in novel water-soluble ruthenium complexes
Authors: Zahirović Adnan , Žilić Dijana , Pavelić Sandra Kraljević , Hukić Mirsada , Muratović Senada , Harej Anja , Kahrović Emira
Published: March 2019

Synthesis, characterization and interaction with BSA and apo-transferrin of novel water-soluble ruthenium complexes having differently coordinated alliin (S-allyl-l-cysteine sulfoxide).
Electrodepositing Pd on NiFe layered double hydroxide for improved water electrolysis
Authors: Guo Jinxue , Sun Jikang , Sun Yanfang , Liu Qingyun , Zhang Xiao
Published: March 2019

Ultrafine Pd nanoparticles with less than 0.12 at% are electrodeposited on nickel foam supported NiFe LDH to obtain improved intrinsic activity, more active sites, and enhanced charge transfer for improved bifunctionality towards overall water splitting.
Pinhole-free TiO2/Ag(O)/ZnO configuration for flexible perovskite solar cells with ultralow optoelectrical loss
Authors: Jeong Eunwook , Bae Soohyun , Park Jong Bae , Yu Seung Min , Kim Donghwan , Lee Hae-Seok , Rha Jongjoo , Cho Young-Rae , Yun Jungheum
Published: March 2019

A TiO2/Ag(O)/ZnO configuration is developed for flexible perovskite solar cells to provide a pinhole-free electron transport layer and a transparent electrode.
Construction of 3D carbon networks with well-dispersed SiOx nanodomains from gelable building blocks for lithium-ion batteries
Authors: Lu Zhitao , Liu Ruliang , Huang Junlong , Chen Zirun , Chen Luyi , Wu Dingcai , Fu Ruowen
Published: March 2019

A novel 3D carbon network with well-dispersed SiOx nanodomains (CNT@SiOx–C) is favorable as an anode material for lithium ion batteries.
Study on the hydrogen production ability of high-efficiency bacteria and synergistic fermentation of maize straw by a combination of strains
Authors: Bao Hongxu , Zhang Xin , Su Hongzhi , Li Liangyu , Lv Zhizhong , Zhang Xinyue
Published: March 2019

B2 + X9 was inoculated at the same time, and 6% were inoculated in a ratio of 1 : 1. At an initial pH of 6, the substrate concentration was 12 g L−1, the culture time was 40 h, and the hydrogen production rate of the combined strain was 12.6 mmol g−1.
Oxidation and hydrogenation of Pd: suppression of oxidation by prolonged H2exposure
Authors: Tamaoka Takehiro , Yoshida Hideto , Takeda Seiji
Published: March 2019

Oxidation of the Pd surface exhibits dependence on the history of pre-exposure to H2.
Associations between H19 polymorphisms and neuroblastoma risk in Chinese children
Authors: Hu Chao , Yang Tianyou , Pan Jing , Zhang Jiao , Yang Jiliang , He Jing , Zou Yan
Published: March 2019

Background H19 polymorphisms have been reported to correlate with an increased susceptibility to a few types of cancers, although their role in neuroblastoma has not yet been clarified.

Materials and methods We investigated the association between three single polymorphisms (rs2839698 G>A, rs3024270 C>G, and rs217727 G>A) and neuroblastoma susceptibility in Chinese Han populations. Three hundred ninety-three neuroblastoma patients and 812 healthy controls were enrolled from the Henan and Guangdong provinces. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to determine the strength of the association of interest.

Results Separated and combined analyses revealed no associations of the rs2839698 G>A, rs3024270 C>G or rs217727 G>A polymorphisms and neuroblastoma susceptibility. In the stratification analysis, female children with rs3024270 GG genotypes had an increased neuroblastoma risk (adjusted OR = 1.61, 95% CI = 1.04–2.50, P=0.032).

Conclusion The rs3024270 GG genotype might contribute to an increased neuroblastoma susceptibility in female Chinese children.
Potential therapeutic targets for atherosclerosis in sphingolipid metabolism
Authors: Yu Zemou , Peng Qing , Huang Yining
Published: March 2019

Sphingolipids, such as sphingomyelins, ceramides, glycosphingolipids, and sphingosine-1-phosphates (S1P) are a large group of structurally and functionally diverse molecules. Some specific species are found associated with atherogenesis and provide novel therapeutic targets. Herein, we briefly review how sphingolipids are implicated in the progression of atherosclerosis and related diseases, and then we discuss the potential therapy options by targetting several key enzymes in sphingolipid metabolism.
Immunological abnormalities in patients with primary biliary cholangitis
Authors: Ma Wen-Tao , Chen De-Kun
Published: March 2019

Primary biliary cholangitis (PBC), an autoimmune liver disease occurring predominantly in women, is characterized by high titers of serum anti-mitochondrial antibodies (AMAs) and progressive intrahepatic cholestasis. The immune system plays a critical role in PBC pathogenesis and a variety of immune cell subsets have been shown to infiltrate the portal tract areas of patients with PBC. Amongst the participating immune cells, CD4 T cells are important cytokine-producing cells that foster an inflammatory microenvironment. Specifically, these cells orchestrate activation of other immune cells, including autoreactive effector CD8 T cells that cause biliary epithelial cell (BEC) injury and B cells that produce large quantities of AMAs. Meanwhile, other immune cells, including dendritic cells (DCs), natural killer (NK) cells, NKT cells, monocytes, and macrophages are also important in PBC pathogenesis. Activation of these cells initiates and perpetuates bile duct damage in PBC patients, leading to intrahepatic cholestasis, hepatic damage, liver fibrosis, and eventually cirrhosis or even liver failure. Taken together, the body of accumulated clinical and experimental evidence has enhanced our understanding of the immunopathogenesis of PBC and suggests that immunotherapy may be a promising treatment option. Herein, we summarize current knowledge regarding immunological abnormalities of PBC patients, with emphasis on underlying pathogenic mechanisms. The differential immune response which occurs over decades of disease activity suggests that different therapies may be needed at different stages of disease.
Fast algorithm for zero‐phase linear filter using discrete cosine transform
Authors: Deng G.
Published: March 2019

This Letter deals with a practical signal processing problem where the filter is zero‐phase and is specified by the frequency response. The authors show that if the signal is symmetrically extended, then the fast Fourier transform (FFT)‐based algorithm can be efficiently implemented by using the discrete cosine transform without signal extension. They extend the proposed algorithm to 2D filters and show that computationally it is at least four times more efficient than the FFT‐based algorithm. A practical application of the new algorithm is a fast Wiener inverse filter, which is used to estimate images taken under the condition of air turbulence.
Spectral width reduction of a laser source by external phase noise compensation
Authors: Thuy H.T. , Won Y.Y. , Seo D.S.
Published: March 2019

A method to reduce the spectral linewidth of a laser source by direct phase noise compensation is proposed and demonstrated experimentally. To extract the phase noise information, the laser output is phase modulated and the in‐ and quadrature‐phases are detected by homodyne mixing. Phase noise compensation is achieved by simply applying an error signal to an external phase modulator, where the error signal is generated to keep the same power level for the detected in‐ and quadrature‐signals. The spectral linewidth of the laser is reduced significantly from 450 to 60 kHz.
Fuzzy economic model predictive control for thermal power plant
Authors: Liu Xiangjie , Cui Jinghan
Published: March 2019

In a modern thermal power plant, fuzzy model predictive control (MPC) is an effective method for realising load tracking and economy of boiler–turbine system, by using fuzzy modelling technique considering the plant thermal dynamic. The power plant economy is generally handled in a hierarchical MPC (HMPC) architecture, in which the upper layer realises the economic optimisation while the low layer realises the dynamic tracking. However, while this HMPC architecture realises the steady‐state optimisation, it may neglect the dynamic optimum of the total power plant process. This study develops a fuzzy economic MPC to utilise the economic index directly as the cost function. It integrates economic optimisation and dynamic tracking of the boiler–turbine system control into one framework. Since a fuzzy model is used to approximate the system's non‐linear behaviour, a linear feedback controller can be constituted for guaranteeing the feasibility and stability of the boiler–turbine system through linear matrix inequality. Simulation results are given to show the effectiveness of the proposed controller.
Electric oil pump design of hybrid continuously variable transmission
Authors: Liu Yunfeng , Zhou Yunshan , Qu Daohai , Zhang Feitie , Bao Xianqi
Published: March 2019

An electric oil pump (EOP) must be used to supply oil for actuators in the hybrid continuously variable transmission (CVT) on the launch state of vehicle. To develop this EOP, the current CVT‐based hybrid schemes and the use of EOP on traditional automatic transmissions are analysed. Permanent magnet synchronous motor (PMSM) type is chosen as the power source of the developed EOP for its advantages of high efficiency and long‐life cycle. The PMSM EOP motor is designed and simulated by ANSYS EM. Based on the parameters of the simulation results, the sensor‐less speed controller of the EOP is designed. Then, the model of the EOP and its load CVT hydraulic system are established by Simulink and AMEsim, respectively, for joint simulation. The simulation results show that the EOP can respond to the speed command request quickly, and when the load of the hydraulic system changes it also can keep the speed stable. Finally, based on the developed prototype of EOP and hybrid CVT, the correctness of the developed EOP and its sensorless speed controller are verified by bench test.
Design and fabrication of two‐port three‐beam switched beam antenna array for 60 GHz communication
Authors: Liu Yuqiao , Bshara Oday , Tekin Ibrahim , Israel Christopher , Hoorfar Ahmad , Taskin Baris , Dandekar Kapil R.
Published: March 2019

This article presents a novel, low‐cost, beam‐switchable antenna array system operating at 60 GHz. This antenna system is constructed of two rows of Chebyshev‐tapered microstrip antenna arrays. Each row is a 10 element series‐fed array which are fed by a coupler. The designed antenna array has only two input ports, but it is capable of generating three switchable beams. This antenna system can spatially scan with at least −5 dB normalised gain using only one SPDT switch and a single transceiver. The maximum gain realised by the system was measured as 16.4 dBi and the bandwidth (BW) was >1 GHz. The features of the proposed antenna system make it applicable to do mmWave research such as beamforming algorithms and channel sounding, and to use in handsets for 5G communication.
Enhanced pulse amplitude estimation for electronic warfare systems
Authors: Lee Yu‐Ri , Kim Dong‐Gyu , Kim Hyoung‐Nam
Published: March 2019

In electronic warfare systems, the pulse amplitude (PA) of the received signals, which are emitted by enemies, has been used as one of the essential quantities for separating the mixed source signals. The PA is affected by time of arrival (TOA) and time of departure (TOD) estimation performance. Among methods of estimating TOA and TOD, there is a method of processing a signal in sample units in the time domain. This method has a disadvantage that it is completely affected by noise. This disadvantage can be overcome by using denoising techniques as in previous studies. However, conventional studies applying denoising are limited to the subject of signal detection, and there is no discussion on the problem of PA estimation due to the TOA and TOD estimation errors that occur after denoising. Therefore, we propose a power estimation‐based PA estimation method using shrinked PW to be robust for TOA and TOD errors in sample units after wavelet packet denoising with high‐order statistics. Simulation results show that the proposed PA estimation method has a smaller error at the same SNR when an unmodulated signal is received. Moreover, the proposed method can provide good performance even when a frequency modulated signal is received.
Consistent accretion-induced heating of the neutron-star crust in MXB 1659−29 during two different outbursts
Authors: Parikh A. S. , Wijnands R. , Ootes L. S. , Page D. , Degenaar N. , Bahramian A. , Brown E. F. , Cackett E. M. , Cumming A. , Heinke C. , Homan J. , Rouco Escorial A. , Wijngaarden M. J. P.
Published: March 2019

Monitoring the cooling of neutron-star crusts heated during accretion outbursts allows us to infer the physics of the dense matter present in the crust. We examine the crust cooling evolution of the low-mass X-ray binary MXB 1659−29 up to ∼505 days after the end of its 2015 outburst (hereafter outburst II) and compare it with what we observed after its previous 1999 outburst (hereafter outburst I) using data obtained from theSwift,XMM-Newton, andChandraobservatories. The observed effective surface temperature of the neutron star in MXB 1659 − 29 dropped from ∼92 eV to ∼56 eV from ∼12 days to ∼505 days after the end of outburst II. The most recently performed observation after outburst II suggests that the crust is close to returning to thermal equilibrium with the core. We model the crust heating and cooling for both its outbursts collectively to understand the effect of parameters that may change for every outburst (e.g. the average accretion rate, the length of outburst, the envelope composition of the neutron star at the end of the outburst) and those which can be assumed to be the same during these two outbursts (e.g. the neutron star mass, its radius). Our modelling indicates that all parameters were consistent between the two outbursts with no need for any significant changes. In particular, the strength and the depth of the shallow heating mechanism at work (in the crust) were inferred to be consistent during both outbursts, contrary to what has been found when modelling the cooling curves after multiple outburst of another source, MAXI J0556−332. This difference in source behaviour is not understood. We discuss our results in the context of our current understanding of cooling of accretion-heated neutron-star crusts, and in particular with respect to the unexplained shallow heating mechanism.
The difficulty of inferring progenitor masses from type-II-Plateau supernova light curves
Authors: Dessart Luc , Hillier D. John
Published: March 2019

Much controversy surrounds the inferred progenitor masses of type-II-Plateau (II-P) supernovae (SNe). The debate is nourished by the discrepant results from radiation-hydrodynamics simulations, pre-explosion imaging, and studies of host stellar populations. Here, we present a controlled experiment using four solar-metallicity models with zero-age main sequence masses of 12, 15, 20, and 25 M⊙. Because of the effects of core burning and surface mass loss, these models reach core collapse as red-supergiant (RSG) stars with a similar H-rich envelope mass of 8 to 9 M⊙ but with final masses in the range 11 to 16 M⊙. We explode the progenitors using a thermal bomb, adjusting the energy deposition to yield an asymptotic ejecta kinetic energy of 1.25 × 1051 erg and an initial 56Ni mass of 0.04 M⊙. The resulting SNe produce similar photometric and spectroscopic properties from 10 to 200 d. The spectral characteristics are degenerate. The scatter in early-time color results from the range in progenitor radii, while the differences in late-time spectra reflect the larger oxygen yields in more massive progenitors. Because the progenitors have a comparable H-rich envelope mass, the photospheric phase duration is comparable for all models; the difference in He-core mass is invisible. As different main sequence masses can produce progenitors with a similar H-rich envelope mass, light-curve modeling cannot provide a robust and unique solution for the ejecta mass of type-II-P SNe. The numerous uncertainties in massive-star evolution and wind-mass loss also prevent a robust association with a main sequence star mass. Light-curve modeling can at best propose compatibility.
Die Biologie der orthodontischen Zahnbewegung – Status quo der Forschung
Authors: Husari Ayman , Jung Britta
Published: March 2019

Die orthodontische Zahnbewegung involviert Zellen des Parodonts und deren Moleküle. Durch die Verbindung von Matrix und Zellen, reagieren die Zellen hierbei mit der Expression bestimmter Moleküle, die dann die Umbauprozesse im Ligament und später im Knochen induzieren, sodass die Zahnbewegung ablaufen kann.
Geschlechterspezifische Inanspruchnahme von Gesundheitsleistungen in einer urbanen Erwachsenenpopulation
Authors: Keil Jan , Brendler Verena , Sachse Catherina , Zülke Andrea , Zeynalova Samira , Engel Christoph , Loeffler Markus , Riedel-Heller Steffi G. , König Hans-Helmut , Stengler Katarina
Published: March 2019

Ziel der Studie Ziel der Studie ist es, Ergebnisse zur geschlechterspezifischen Inanspruchnahme von Gesundheitsleistungen in einer urbanen Erwachsenenpopulation bereitzustellen.

Methoden Im Zuge der LIFE-ADULT-Studie wurden 2244 Erwachsene (19–79 Jahre) zum Inanspruchnahmeverhalten von Gesundheitsleistungen innerhalb des letzten Jahres befragt. Die Angaben zu Haus- und Facharztkonsultation, hausärztliche Beratung sowie Inanspruchnahme präventiver- bzw. gesundheitsfördernder Maßnahmen wurden ausgewertet.

Ergebnisse Frauen nahmen innerhalb eines Jahres häufiger Haus- oder Fachärzte sowie präventive bzw. gesundheitsfördernde Maßnahmen in Anspruch. Keine Geschlechterunterschiede ergaben sich bezüglich der hausärztlichen Beratungshäufigkeit.

Schlußfolgerung Die vorliegende Studie bestätigt weitestgehend bisherige Befunde zur häufigeren Inanspruchnahme von Gesundheitsleistungen seitens der Frauen. Allerdings zeigt sich auch, dass die geschlechterspezifische Inanspruchnahme vom verwendeten Indikator abhängig ist und daher stets differenziert diskutiert werden sollte.
Die Nadeln im Heuhaufen finden: Qualitätskriterien für den Einsatz von internetbasierten Selbstmanagement-Interventionen in Prävention und Behandlung psychischer Störungen
Authors: Klein Jan Philipp , Knaevelsrud Christine , Bohus Martin , Ebert David Daniel , Gerlinger Gabriel , Günther Kristina , Jacobi Corinna , Löbner Margrit , Riedel-Heller Steffi G. , Sander Julia , Sprick Ulrich , Hauth Iris
Published: March 2019

Zahlreiche Selbstmanagement Interventionen haben in randomisierten Studien ihre Wirksamkeit in der Behandlung von einer Reihe von psychischen Störungen gezeigt. Dennoch sind diese Interventionen gegenwärtig noch nicht überall in der klinischen Routine angekommen. Das liegt unter anderem daran, dass neben den evidenzbasierten Interventionen auch Interventionen angeboten werden, die nie wissenschaftlich untersucht worden sind und teilweise noch nicht einmal auf evidenzbasierten Psychotherapiemethoden beruhen. Die vorliegenden Qualitätskriterien der beiden Fachgesellschaften DGPs und DGPPN sollen Betroffenen, Behandlern und Entscheidern im Gesundheitswesen helfen, sichere und wirksame Interventionen zu identifizieren. Im Mittelpunkt der Qualitätskriterien stehen die Sicherheit der Patienten und ihrer Daten; die Sicherstellung der therapeutischen Qualität durch Rückgriff auf evidenzbasierte Psychotherapiemethoden und Begleitung der Entwicklung durch approbierte Psychotherapeuten oder Fachärzte; das Vorliegen eines Wirksamkeitsnachweises aus mindestens einer randomisierten Studie; und die Transparenz bezüglich zentraler Informationen, z. B. der Kosten der Intervention. Wir hoffen, dass diese Kriterien dazu beitragen können, dass Selbstmanagement Interventionen in den Leistungskatalog der Krankenkassen aufgenommen werden.
Cascades Involving anti-Carbopalladation Steps: From Our Initial Hypothesis to Natural Product Synthesis
Authors: Schitter Theresa , Reding Andreas , Werz Daniel B.
Published: March 2019

Our endeavors in the design, realization and application of a formal anti-carbopalladation of alkynes are summarized. Whereas numerous examples of syn-carbopalladation steps embedded in cascade reactions are known, there have been almost no examples of the corresponding anti-carbopalladation steps. From a personal perspective, this account provides insights on the original considerations and hypotheses, and their validation or invalidation by experimental and computational means. This account also aims at clarifying how different ideas have been developed and how novel reaction sequences paving the way to a plethora of different scaffolds have been designed. The reader will recognize the importance of the interplay between elucidating reaction mechanisms and developing novel methodologies. As a result, useful methods to create homo- and heterotetrasubstituted double bonds have been developed. The broad versatility of these methods has been demonstrated by a novel total synthesis of the indole alkaloid (+)-lysergol.

1 Introduction

2 Initial Studies

3 Various Termination Steps

4 Termination with Heteronucleophiles

5 Natural Product Synthesis

6 anti-Carbopalladations Realized by the Lautens Lab

7 Conclusion and Outlook
Novel Coagulation Analyzers in Development: A Glimpse toward the Future of Microfluidics
Authors: Emani Sitaram
Published: March 2019

Coagulation diagnostic testing in pediatric patients currently requires large volume blood sampling and is performed on analyzers that are not well-suited for multiplexed assays on a given sample. For patients who require serial testing at regular intervals, repetitive phlebotomy leads to iatrogenic anemia and need for blood transfusions. Over the past decade, novel microfluidic platforms have been developed that allow for complex multiplexed assays to be performed on small sample volumes, near patient, with high fidelity. In the next few years, these devices will be introduced into clinical trials, and offer the promise of reliable, rapid, multiplexed coagulation assays for pediatric patients who require coagulation diagnostic testing.
Transitions between channel and contact regimes of low-frequency noise in many-layer MoS2 field effect transistors
Authors: Kwon Jiseok , Park Joon Hyeong , Delker Collin J. , Harris Charles T. , Swartzentruber Brian , Das Suprem R. , Janes David B.
Published: March 2019

Low-frequency noise studies in transition metal dichalcogenides have considered the layer-thickness dependence but generally do not separate channel contributions from those of contact/access regions. Here, we study the voltage-dependent 1/f noise and the resistance correlation in MoS2 FETs with an ∼142 atomic layer-thickness channel and three different lengths. The gate-voltage dependence of noise can be separated into a channel contribution, with a comparable Hooge parameter for the three devices and a contact/access region contribution. Separation of these contributions allows the evaluation of the channel noise mechanism and can be used to explain the length-dependence of the transition region between contact- and channel-dominated regimes.
Enhancement-mode Al0.85Ga0.15N/Al0.7Ga0.3N high electron mobility transistor with fluorine treatment
Authors: Klein Brianna A. , Douglas Erica A. , Armstrong Andrew M. , Allerman Andrew A. , Abate Vincent M. , Fortune Torben R. , Baca Albert G.
Published: March 2019

Enhancement-mode Al0.7Ga0.3N-channel high electron mobility transistors (HEMTs) were achieved through a combination of recessed etching and fluorine ion deposition to shift the threshold voltage (VTH) relative to depletion-mode devices by +5.6 V to VTH = +0.5 V. Accounting for the threshold voltage shift (ΔVTH), current densities of approximately 30 to 35 mA/mm and transconductance values of 13 mS/mm were achieved for both the control and enhancement mode devices at gate biases of 1 V and 6.6 V, respectively. Little hysteresis was observed for all devices, with voltage offsets of 20 mV at drain currents of 1.0 × 10−3 mA/mm. Enhancement-mode devices exhibited slightly higher turn-on voltages (+0.38 V) for forward bias gate currents. Piecewise evaluation of a threshold voltage model indicated a ΔVTH of +3.3 V due to a gate recess etching of 12 nm and an additional +2.3 V shift due to fluorine ions near the AlGaN surface.
Stability of magnetocaloric La(FexCoySi1-x-y)13 in water and air
Authors: Javed Khushar , Gupta Shalabh , Pecharsky Vitalij K. , Hadimani Ravi L.
Published: March 2019

Stability of cobalt-doped lanthanum iron silicide, La(FexCoySi1-x-y)13 have been investigated under conditions required for magnetocaloric refrigeration. The XRD analysis revealed that both milled and non-milled samples stored in water loose a few Bragg peaks corresponding to the NaZn13 phase of La(FexCoySi1-x-y)13. Samples stored in air show well-defined Bragg peaks similar to that of pristine material. The SEM-EDS of the milled and non-milled samples stored in water and air show an increased concentration of oxygen in the samples, particularly those treated with water. The course non-milled powders stored in air and water show sharp transitions at the Curie temperature TC = 300K without large magnetization above the TC. The milled, fine-particulate sample stored in air shows a slightly broadened transition at TC, and that stored in deionized water for 14 days shows significantly broadened transition from 300K and retains large magnetizations above 400 K. This is indicative of relatively fast hydrolysis and removal of some or all of La, likely as hydroxide, from fine powders, leaving behind La-poor or, potentially, La-free Fe-Co-Si containing ferromagnetic residue with much higher Curie temperature. The non-milled course sample stored in water has sharper magnetic transition and higher magnetization hence it shows the highest entropy change among all 4 type of samples.
Mg assisted flux growth and characterization of single crystalline Sm2Co17
Authors: Lamichhane Tej Nath , Lin Qisheng , Taufour Valentin , Palasyuk Andriy , Pandey Tribhuwan , Parker David , Bud’ko Sergey L. , Canfield Paul C.
Published: March 2019

This paper presents details of Mg-assisted flux growth of Sm2Co17 single crystals in a Ta crucible well below the melting temperature of binary Sm2Co17. Both the crushed single crystalline powder x-ray diffraction (XRD) and single crystalline XRD data revealed the Th2Zn17 type rhombohedral(R-3m) crystal structure. Ta atom is found to be statistically replacing the Co-Co dumbbell with its position being at the center of the dumbbell. The Curie temperature of our lightly Mg and Ta doped Sm2Co17 sample is determined to be ∼1100 K using method of generalized Bloch law fitting of easy axis spontaneous magnetization data.
Dependence of transition behaviors on structure of Sb100−xErx films for broadband nonvolatile optical memory
Authors: Yin Bohai , Lu Yegang , Meng Yun , Li Zengguang , Xu Meng , Wang Guoxiang , Shen Xiang
Published: March 2019

The crystallization temperature (Tc) and 10-year data-retention temperature enhance from 176 °C to 217 °C and from 61.5 °C to 120.6 °C, respectively, when the Er concentration increases from 16 at. % to 28 at. % for Sb100−xErx films. The improvement in the thermal stability of the Sb100−xErx results from Er doping induced the suppression of the A1g mode from Sb-Sb bonds. The fast crystallization of the Sb100−xErx film is ascribed to the growth-dominated crystallization mechanism which was confirmed by the in situ microstructure observation. A large optical contrast of Sb100−xErx such as high ON/OFF ratios of both the refractive index (n) and the extinction coefficient (k) between the amorphous and crystalline states results from the formation of resonant bonding in crystalline states. Sb100−xErx demonstrated the repeatable and reversible phase change between two states induced by optical pulses, suggesting a potential candidate for optical storage.
A method for single molecule tracking using a conventional single-focus confocal setup
Authors: Jazani Sina , Sgouralis Ioannis , Pressé Steve
Published: March 2019

One way to achieve spatial resolution using fluorescence imaging—and track single molecules—is to use wide-field illumination and collect measurements over multiple sensors (camera pixels). Here we propose another way that uses confocal measurements and a single sensor. Traditionally, confocal microscopy has been used to achieve high temporal resolution at the expense of spatial resolution. This is because it utilizes very few, and commonly just one, sensors to collect data. Yet confocal data encode spatial information. Here we show that non-uniformities in the shape of the confocal excitation volume can be exploited to achieve spatial resolution. To achieve this, we formulate a specialized hidden Markov model and adapt a forward filtering-backward sampling Markov chain Monte Carlo scheme to efficiently handle molecular motion within a symmetric confocal volume characteristically used in fluorescence correlation spectroscopy. Our method can be used for single confocal volume applications or incorporated into larger computational schemes for specialized, multi-confocal volume, optical setups.
Comparative collisionless alpha particle confinement in stellarator reactors with the XGC gyrokinetic code
Authors: Cole M. D. J. , Hager R. , Moritaka T. , Lazerson S. , Kleiber R. , Ku S. , Chang C. S.
Published: March 2019

Whole volume simulations of stellarators are necessary to address a number of important physics and engineering issues, including turbulent transport prediction and optimising divertor operation. In this work, advances in the development of a whole volume stellarator capability for the global gyrokinetic particle-in-cell code XGC are detailed. A 3D interpolation of the equilibrium magnetic field to the last close flux surface, calculated using the VMEC ideal magnetohydrodynamic equilibrium code, has been implemented. Orbit tracing with the XGC code is verified for the Wendelstein 7-X stellarator by comparison with the BEAMS3D and EUTERPE codes. The XGC stellarator version has then been used to consider collisionless alpha particle confinement in representative quasi-isodynamic and quasi-axisymmetric designs. It has been shown that, at least without further optimisation for energetic particle confinement, the Wendelstein 7-X-like quasi-isodynamic reactor design exhibits better alpha particle confinement.
Influence of dielectric constant on dielectric strength by defect discharge and molecular polarization in solid insulation materials
Authors: Liu Jing , Su Jiancang , Zhao Liang , Li Rui , Lu Yuanrong , Liu Xiaolong
Published: March 2019

Dielectric constant and dielectric strength are two intrinsic electrical parameters of solid insulating materials. In order to finally understand the relationship between them, the one-sided influence of dielectric constant on dielectric strength is investigated. For theoretical analysis, we propose that the influence is realized indirectly by two mechanisms: defect discharge in the micro level and molecular polarization in the nanoscale. The transition phase is composed of the field enhancement related to permittivity and the breakdown of defect molecular bond. While the local field around the bond is always higher than the cavity interior field, the breakdown field is a competition between the two mechanisms. According to the simulation model of electrostatic field, the electric field around the cavity is significantly enhanced with a larger dielectric constant. In view of the simulation result of partial discharge, the discharge intensity of dielectric and gas breakdown in the cavity is promoted by the increase of material permittivity. To confirm the defect distribution and quantity, several prepared samples are scanned with the ultrasonic microscope and the cavities are measured via image software. Based on the published experiment data from oxide films and polymer bulks, a revised relationship is plotted and fitted for the dielectric strength and the dielectric constant. As molecular polarization is applicable to oxide films with few defects and high permittivities, defect discharge is more effective for polymer bulks with generous cavities and low permittivities. Since molecular polarization leads to breakdown by enhancing the local electric field, cavity discharge is mainly due to the lower breakdown threshold of defect.
Analytic Wigner distribution function for tunneling and trajectory models
Authors: Jensen K. L. , Shiffler D. A. , Lebowitz J. L. , Cahay M. , Petillo J. J.
Published: March 2019

The Wigner function is assembled from analytic wave functions for a one-dimensional closed system (well with infinite barriers). A sudden change in the boundary potentials allows for the investigation of time-dependent effects in an analytically solvable model. A trajectory model is developed to account for tunneling when the barrier is finite. The behavior of the density (the zeroth moment of the Wigner function) after an abrupt change in potential shows net accumulation and depletion over time for a weighting of energy levels characteristic of the supply function in field emission. However, for a closed system, the methods have application to investigations of tunneling and transmission associated with field and photoemission at short time scales.
The dispersion properties of three-dimensional woodpile magnetized plasma photonic crystals including function dielectric under magneto-optical Faraday effect
Authors: Zhang Hai-Feng , Zeng Li , Chen Yu-Qing
Published: March 2019

In this paper, the dispersion properties of three-dimensional function magnetized plasma photonic crystals (FMPPCs) are theoretically studied by a modified plane wave expansion method, when the magneto-optical Faraday effect is considered, and the directions of the electromagnetic wave vector and the extrinsic magnetic field are always parallel to each other. The arrangement of these FMPPCs is that the function dielectric square columns are embedded into the plasma background, and the inserted dielectric columns are arranged by woodpile lattices with face-centered-tetragonal symmetry. The relative permittivity of function square columns depends on the space coordinates. The relationships between the parameters of FMPPCs and the photonic bandgaps (PBGs) for the right and left circular polarization waves also are investigated. The calculated results demonstrate that those PBGs can be tailored by those parameters, and the right and left circular polarization waves can be split when the extrinsic magnetic field is large enough.
Three dimensional Darcy-Forchheimer radiated flow of single and multiwall carbon nanotubes over a rotating stretchable disk with convective heat generation and absorption
Authors: Nasir Saleem , Shah Zahir , Islam Saeed , Khan Waris , Bonyah Ebenezer , Ayaz Muhammad , Khan Aurangzeb
Published: March 2019

Several important characteristics of CNTs (carbon nanotubes) like excellent electrical conductivities, extraordinary thermal conductivities, good mechanical and chemical stability and extremely light mass make CNTs a model material which is utilized in various electro-chemical mechanisms. Keeping the said significance of carbon nanotubes in notice our main aim in this analysis is to establish the import relation of Darcy Forchheimer in three dimensional (3D) flows of classical fluid (water) based CNTs in presence of slip velocity due to rotating stretchable disk. Analysis of nanoparticles like single and multi-walled (SWCNTs, MWCNTs) carbon nanotubes are developed and equated. Present investigation further comprises non-linear thermal radiation, heat generation/absorption as well as convective thermal boundary condition aspects. The pertinent non-linear ordinary differential equations after utilizing the appropriate variables are calculated. HAM (Homotopy Analysis Method) technique is utilized for the analysis of velocities and thermal distribution. Various graphs have been plotted in order to examine that by what means the velocities and thermal field are altered by different model quantities. The main features of flow like the CFReα, CGReα (skin friction), Nu(Reα)−1/2 (heat transfer rate) have been intended numerically and graphically.
High-temperature annealing induced evolution of strain in AlN epitaxial films grown on sapphire substrates
Authors: Wang M. X. , Xu F. J. , Xie N. , Sun Y. H. , Liu B. Y. , Ge W. K. , Kang X. N. , Qin Z. X. , Yang X. L. , Wang X. Q. , Shen B.
Published: March 2019

High-temperature (HT) annealing effects on the evolution of strain in AlN films grown on sapphire have been investigated. It is found that there is a significant transition behavior from tensile to compressive strain in AlN before and after HT annealing at an optimal temperature of 1700 °C. Based on a microstructural analysis, it is clarified that the HT annealing will result in the (1) disappearance of grains that account for the tensile stress before HT annealing, (2) generation of a new interface that has little influence on the lattice constant upper/below this interface, and (3) regular 8/9 arrangement of misfit dislocation at the AlN/sapphire interface that relieves almost all stress associated with lattice mismatch. It is thus deduced that the remnant compressive strain in AlN after HT annealing mainly comes from the cooling down process due to thermal mismatch between sapphire and AlN. This understanding of the annealing effect is certainly of great significance in AlN materials science and technology.
Self-oscillations in an over-injected electron diode – Experiment and analysis
Authors: Siman-Tov M. , Leopold J. G. , Krasik Ya. E.
Published: March 2019

An experimental setup to demonstrate a recent scheme [Leopold et al., Phys. Plasmas 24, 073116 (2017)] to persistently over-inject a vacuum electron diode so that it self-oscillates in the GHz-frequency range and releases a periodic train of electron bunches is described. We present simulations in which we account for the finite rise time of the voltage accelerating electrons from a finite radius cylindrical thermionic cathode and finite grid electrode transparency, which make the experiment different from the original theoretical scheme. It was found that these experimental conditions do affect the expected results but a self-oscillating behavior is still possible. Our experimental results so far indicate the presence of the self-oscillatory behavior, but because the cathode used emits from a few hot-spots rather than uniformly, the beam current modulations are different from those obtained in the simulations.
Comparison of photothermal responses under spatial and temporal modulations of CW Gaussian beam excitation: A numerical study
Authors: Dong Jingtao , Lu Rongsheng , Wu Zhouling , Chen Jian
Published: March 2019

Obtaining stronger photothermal response of optical materials is of great interest in the measurement of optical losses using the photothermal tools, in particular the thermal mirror. In our previous work, we experimentally demonstrated a more effective method of thermal mirror detection employing the spatial modulation (SM) of a continuous wave Gaussian beam excitation instead of the conventional temporal modulation (TM). A complete analytical model is presented to describe the laser-induced three-dimensional dynamic thermal fields in a semi-infinite sample and the time-dependent thermal mirror due to the thermoelastic response of the material as well as the evolution of the intensity distribution of a probe beam after interacting with the thermal mirror, in both the SM and TM schemes under the low absorption and exponentially-decaying absorption cases. With the model, we obtained the variations of temperature, surface displacement, and diffraction intensity giving rise to the photothermal response of the material. The results of the comparison between the two schemes reveal that the SM scheme is more sensitive than the TM scheme originating from a large variation range of the temperature in the SM scheme. We also explained the complex relation between the surface displacement and the diffraction intensity of the probe beam at the center of the detection plane on the basis of the phase shift caused by the thermal mirror. The presented model and the results of comparison are of great importance to gain a deeper insight into the photothermal characterization in both the SM and TM schemes.
Buckling of metallic glass supercooled liquid layer during embossing
Authors: Meduri Chandra Sekhar , Hu Zhonglue , Blawzdziewicz Jerzy , Kumar Golden
Published: March 2019

Embossing of metallic glass supercooled liquids into templates is emerging as a precision net-shaping and surface patterning technique for metals. Here, we report the effect of thickness of metallic glass on template-based embossing. The results show that the existing embossing theory developed for thick samples fails to describe the process when the thickness of metallic glass becomes comparable to the template cavity diameter. The increased flow resistance at the cavity entrance results in viscous buckling of supercooled liquid instead of filling. A phenomenological equation is proposed to describe the thickness dependent filling of template cavities. The buckling phenomenon is analyzed based on the folding model of multilayer viscous media. We show that controlled buckling can be harnessed in the fabrication of metal microtubes, which are desirable for many emerging applications.
Understanding rotational mode specificity in the O(3P)+CHD3→ OH+CD3 reaction by simple reactant alignment pictures
Authors: Liu Rui , Song Hong-wei , Yang Ming-hui
Published: March 2019

The mode specificity plays an important role in understanding the fundamental reaction dynamics. This work reports a theoretical study of the rotational mode specificity of the reactant CHD3(JK) in the prototypical hydrocarbon oxidation reaction O(3P)+CHD3→OH+CD3. The time-dependent quantum wave packet method combined with a seven-dimensional reduced model is employed to calculate the reaction probability on an accurate potential energy surface. The obtained reaction probability depends on the values of both K and Ktot with PKtot = K = 0 > PKtot = K = J > PKtot = J,K = 0 = PKtot = 0,K = J. This observation can be well rationalized by the reactant alignment pictures. Rotational excitations of CHD3 up to the angular momentum quantum number J = 4 have a very weak enhancement effect on the reaction except for the state (J = 4, K = 0). In addition, the rotationally excited states of CHD3 with K = 0 promote the reaction more than those with K = J. The quantum dynamics calculations indicate that the K = 0 enhancements are mainly caused by the contributions from the components with K = Ktot = 0. The components correspond to the tumbling rotation of CHD3, which enlarges the range of the reactive initial attack angles.
Ultrafast dynamics of water molecules excited to electronic F̃ states: A time-resolved photoelectron spectroscopy study
Authors: Yang Dong-yuan , Min Yan-jun , Chen Zhen , He Zhi-gang , Chen Zhi-chao , Yuan Kai-jun , Dai Dong-xu , Wu Guo-rong , Yang Xue-ming
Published: March 2019

The ultrafast dynamics of water molecules excited to the two F̃ states is studied by combining two-photon excitation and time-resolved photoelectron imaging techniques. The lifetimes of the F̃1A1 and F̃1B1 states of H2O (D2O) were derived to be 1.0±0.3 (1.9±0.4) and 10±3 (30±10) ps, respectively. We propose that the F̃1A1 state mainly decays through the D̃ state, due to the nonadiabatic coupling between them, while the F̃1B1 state decays through the F̃1A1 state via Coriolis interaction.