bluuebunny/crossref_metadata_2025 huggingface dataset:
A mini-review on the synthesis and structural modification of g-C3N4-based materials, and their applications in solar energy conversion and environmental remediation
Authors: Ismael Mohammed , Wu Ying
Published: August 2019

Recently, graphitic carbon nitride (g-C3N4) as a metal-free conjugated polymer has emerged as a photocatalyst showing catalytic activity for water splitting, CO2photoreduction and degradation of organic pollutants under visible light irradiation.
Crystal structures of Magnaporthe oryzae trehalose-6-phosphate synthase (MoTps1) suggest a model for catalytic process of Tps1
Authors: Wang Shanshan , Zhao Yanxiang , Yi Long , Shen Minghe , Wang Chao , Zhang Xin , Yang Jun , Peng You-Liang , Wang Dongli , Liu Junfeng
Published: August 2019

Trehalose-6-phosphate (T6P) synthase (Tps1) catalyzes the formation of T6P from UDP-glucose (UDPG) (or GDPG, etc.) and glucose-6-phosphate (G6P), and structural basis of this process has not been well studied. MoTps1 (Magnaporthe oryzae Tps1) plays a critical role in carbon and nitrogen metabolism, but its structural information is unknown. Here we present the crystal structures of MoTps1 apo, binary (with UDPG) and ternary (with UDPG/G6P or UDP/T6P) complexes. MoTps1 consists of two modified Rossmann-fold domains and a catalytic center in-between. Unlike Escherichia coli OtsA (EcOtsA, the Tps1 of E. coli), MoTps1 exists as a mixture of monomer, dimer, and oligomer in solution. Inter-chain salt bridges, which are not fully conserved in EcOtsA, play primary roles in MoTps1 oligomerization. Binding of UDPG by MoTps1 C-terminal domain modifies the substrate pocket of MoTps1. In the MoTps1 ternary complex structure, UDP and T6P, the products of UDPG and G6P, are detected, and substantial conformational rearrangements of N-terminal domain, including structural reshuffling (β3–β4 loop to α0 helix) and movement of a ‘shift region' towards the catalytic centre, are observed. These conformational changes render MoTps1 to a ‘closed' state compared with its ‘open' state in apo or UDPG complex structures. By solving the EcOtsA apo structure, we confirmed that similar ligand binding induced conformational changes also exist in EcOtsA, although no structural reshuffling involved. Based on our research and previous studies, we present a model for the catalytic process of Tps1. Our research provides novel information on MoTps1, Tps1 family, and structure-based antifungal drug design.
Widespread QSO-driven outflows in the early Universe
Authors: Bischetti M. , Maiolino R. , Carniani S. , Fiore F. , Piconcelli E. , Fluetsch A.
Published: August 2019

We present the stacking analysis of a sample of 48 quasi-stellar objects (QSOs) at 4.5 <  z <  7.1 detected by the Atacama Large Millimetre Array (ALMA) in the [CII]λ158μm emission line to investigate the presence and the properties of massive, cold outflows associated with broad wings in the [CII] profile. The high sensitivity reached through this analysis allows us to reveal very broad [CII] wings tracing the presence of outflows with velocities in excess of 1000 km s−1. We find that the luminosity of the broad [CII] emission increases withLAGN, while it does not significantly depend on the star formation rate of the host galaxy, indicating that the central active galactic nucleus (AGN) is the main driving mechanism of the [CII] outflows in these powerful, distant QSOs. From the stack of the ALMA cubes, we derive an average outflow spatial extent of ∼3.5 kpc. The average atomic neutral mass outflow rate inferred from the stack of the whole sample isṀout∼ 100M⊙yr−1, while for the most luminous systems it increases to ∼200 M⊙yr−1. The associated outflow kinetic power is about 0.1% ofLAGN, while the outflow momentum rate is ∼LAGN/cor lower, suggesting that these outflows are either driven by radiation pressure onto dusty clouds or, alternatively, are driven by the nuclear wind and energy conserving but with low coupling with the interstellar medium. We discuss the implications of the resulting feedback effect on galaxy evolution in the early Universe.
Calibration of the angular momenta of the minor planets in the solar system
Authors: Li Jian , Xia Zhihong Jeff , Zhou Liyong
Published: August 2019

Aims.We aim to determine the relative angle between the total angular momentum of the minor planets and that of the Sun-planets system, and to improve the orientation of the invariable plane of the solar system.

Methods.By utilizing physical parameters available in public domain archives, we assigned reasonable masses to 718 041 minor planets throughout the solar system, including near-Earth objects, main belt asteroids, Jupiter trojans, trans-Neptunian objects, scattered-disk objects, and centaurs. Then we combined the orbital data to calibrate the angular momenta of these small bodies, and evaluated the specific contribution of the massive dwarf planets. The effects of uncertainties on the mass determination and the observational incompleteness were also estimated.

Results.We determine the total angular momentum of the known minor planets to be 1.7817 × 1046g cm2s−1. The relative angleαbetween this vector and the total angular momentum of the Sun-planets system is calculated to be about 14.74°. By excluding the dwarf planets Eris, Pluto, and Haumea, which have peculiar angular momentum directions, the angleαdrops sharply to 1.76°; a similar result applies to each individual minor planet group (e.g., trans-Neptunian objects). This suggests that, without these three most massive bodies, the plane perpendicular to the total angular momentum of the minor planets would be close to the invariable plane of the solar system. On the other hand, the inclusion of Eris, Haumea, and Makemake can produce a difference of 1254 mas in the inclination of the invariable plane, which is much larger than the difference of 9 mas induced by Ceres, Vesta, and Pallas as found previously. By taking into account the angular momentum contributions from all minor planets, including the unseen ones, the orientation improvement of the invariable plane is larger than 1000 mas in inclination with a 1σerror of ∼50−140 mas.
Rest-frame far-ultraviolet to far-infrared view of Lyman break galaxies at z = 3: Templates and dust attenuation
Authors: Álvarez-Márquez J. , Burgarella D. , Buat V. , Ilbert O. , Pérez-González P. G.
Published: August 2019

Aims. This work explores, from a statistical point of view, the rest-frame far-ultraviolet (FUV) to far-infrared (FIR) emission of a population of Lyman-break galaxies (LBGs) at z ∼ 3 that cannot be individually detected from current FIR observations.

Methods. We performed a stacking analysis over a sample of ∼17 000 LBGs at redshift 2.5 <  z <  3.5 in the COSMOS field. The sample is binned as a function of UV luminosity (LFUV), UV continuum slope (βUV), and stellar mass (M*), and then stacked at optical (BVriz bands), near-infrared (YJHKs bands), IRAC (3.6, 4.5, 5.6, and 8.0 μm), MIPS (24 μm), PACS (100 and 160 μm), SPIRE (250, 350, and 500 μm), and AzTEC (1.1 mm) observations. We obtained 30 rest-frame FUV-to-FIR spectral energy distributions (SEDs) of LBGs at z ∼ 3, and analyzed these with the CIGALE SED-fitting analysis code. We were able to derive fully consistent physical parameters, that is, M*, βUV, LFUV, LIR, AFUV, star formation rate, and the slope of the dust attenuation law; we built a semiempirical library of 30 rest-frame FUV-to-FIR stacked LBG SEDs as functions of LFUV, βUV, and M*.

Results. We used the so-called IR-excess (IRX ≡ LIR/LFUV) to investigate the dust attenuation as a function of βUV and M*. Our LBGs, averaged as a function of βUV, follow the well-known IRX–βUV calibration of local starburst galaxies. Stacks as a function of M* follow the IRX–M* relationship presented in the literature at high M* (log(M* [M⊙]) >  10). However, a large dispersion is shown in the IRX–βUV and IRX–M* planes, in which the βUV and M* are combined to average the sample. Additionally, the SED-fitting analysis results provide a diversity of dust attenuation curve along the LBG sample, and their slopes are well correlated with M*. Steeper dust attenuation curves than Calzetti’s are favored in low stellar mass LBGs (log(M* [M⊙]) <  10.25), while grayer dust attenuation curves are favored in high stellar mass LBGs (log(M* [M⊙]) >  10.25). We also demonstrate that the slope of the dust attenuation curves is one of the main drivers that shapes the IRX–βUV plane.
The prevalence of post-traumatic stress disorder among emergency nurses: a cross sectional study in northern Iran
Authors: Hosseininejad Seyed Mohammad , Jahanian Fatemeh , Elyasi Forouzan , Mokhtari Hossein , Koulaei Mohammad Eslami , Pashaei Seyedeh Masoumeh
Published: August 2019

Background and objective: Posttraumatic stress disorder (PTSD) is one of the anxiety disorders which occurs in response to facing events and accidents accompanied by fear, frustration, and terror. Nurses who worked in the emergency departments witness unpleasant accidents and are exposed to stress and violence more than others. The aim of this study was to investigate the prevalence of PTSD among Iranian nurses working in the emergency department.

Materials and Methods: In this cross-sectional study, all nurses working in the emergency department of educational hospitals affiliated with Mazandaran University of Medical Sciences were included through census method (n = 131). Each of the participants in this study responded to the questionnaires individually. The first part of the questionnaire captured demographics, while the second part was the Civilian Mississippi Scale for PTSD, which was used to investigate the extent of PTSD in this study. Data were analyzed using SPSS version 22.

Results: In this study, 131 respondents were included. In the classification of age, nurses with 20-30-year- old had the maximum frequency (41.2 %,). Most nurses in the study (93.1%, n = 122) had a bachelor’s degree in nursing and 84 were married. The prevalence of PTSD in emergency nurses was 82.96%, which was higher in nurses with shorter working background and nurses with lower levels of education. Further, the average score of PTSD was higher in married nurses.

Conclusion: The results of this study revealed the high prevalence of PTSD among nurses who worked in emergency department. Therefore, it seems that designing and providing supportive and educational services to emergency nurses can be effective for preventing and managing this disorder, which probably can improve their performance.
On a two-phase Serrin-type problem and its numerical computation
Authors: Cavallina Lorenzo , Yachimura Toshiaki
Published: August 2019

We consider an overdetermined problem of Serrin-type with respect to an operator in divergence form with piecewise constant coefficients. We give sufficient condition for unique solvability near radially symmetric configurations by means of a perturbation argument relying on shape derivatives and the implicit function theorem. This problem is also treated numerically, by means of a steepest descent algorithm based on a Kohn–Vogelius functional.
Local state observation for stochastic hyperbolic equations
Authors: Lü Qi , Yin Zhongqi
Published: August 2019

In this paper, we solve a local state observation problem for stochastic hyperbolic equations without boundary conditions, which is reduced to a local unique continuation property for these equations. This result is proved by a global Carleman estimate. As far as we know, this is the first result in this topic.
On the partial controllability of SDEs and the exact controllability of FBSDES
Authors: Wang Yanqing , Yu Zhiyong
Published: August 2019

A notion of partial controllability (also can be called directional controllability or output controllability) is proposed for linear controlled (forward) stochastic differential equations (SDEs), which characterizes the ability of the state to reach some given random hyperplane. It generalizes the classical notion of exact controllability. For time-invariant system, checkable rank conditions ensuring SDEs’ partial controllability are provided. With some special setting, the partial controllability for SDEs is proved to be equivalent to the exact controllability for linear controlled forward-backward stochastic differential equations (FBSDEs). Moreover, we obtain some equivalent conclusions to partial controllability for SDEs or exact controllability for FBSDEs, including the validity of observability inequalities for the adjoint equations, the solvability of some optimal control problems, the solvability of norm optimal control problems, and the non-singularity of a random version of Gramian matrix.
Vorsorgeuntersuchungen und Check-ups in der Gastroenterologie
Authors: Fischbach Wolfgang
Published: August 2019

Diseases of the digestive tract are frequent and many gastroenterological tumors are characterized by a bad prognosis. Lifestyle changes such as normalization of body weight, physical activity, stop smoking or balanced diets can effectively prevent many gastroenterological tumors. Vaccination against hepatitis A and B, as well as eradication of Helicobacter pylori, are highly effective in avoiding liver infection and reducing the risk for gastric cancer respectively. Colorectal cancer screening using immunological stool tests (iFOBT) and colonoscopy has been proven to be the most efficacious tool in tumour screening at all. As compared to established screening tests, check-ups and their benefit are less well defined. In general, they yield to detect health risks, partially overlapping with the goals of prevention and screening. Gastroenterological check-ups include abdominal ultrasound and esophagogastroduodenoscopy offering a wide range of detecting diseases at potential risks like reflux esophagitis and their complications or aortal aneurysma.
Senkt Fußballspielen den Blutdruck?
Authors: Schrader Joachim
Published: August 2019

Playing football leads to a sustainable improvement of cardiovascular risk factors, especially to a reduction of blood pressure in hypertension. For certain target groups football is more attractive with its team character than individual sports. However, the existing studies are not sufficient for an evidence-based recommendation. Therefore, no medical society explicitly recommends football for lowering blood pressure. Urgent studies are needed to adequately evaluate the value of football as a health sport. This includes a special training program and rules, the involvement of football clubs in these programs, the training of appropriate coaches and the involvement of interested physicians. Football could, with its popularity, motivate more people to exercise and contribute to a sustained reduction in cardiovascular disease.
Zwangssterilisationen in Thüringen und Württemberg 1933–1945
Authors: Kinas Sven
Published: August 2019

Bei der Durchführung des Gesetzes zur Verhütung erbkranken Nachwuchses vom 14 Juli 1933 (GzVeN) kam den an den Staatlichen Gesundheitsämtern tätigen Amtsärzten eine Schlüsselfunktion zu. Sie verfassten einen Großteil der Sterilisationsanzeigen, stellten die überwiegende Mehrheit der Sterilisationsanträge und wirkten als Gutachter oder Richter an den Entscheidungen der Erbgesundheitsgerichte mit. Der Beitrag präsentiert genaue Zahlen zu den Folgen der Sterilisationspolitik in Thüringen und Württemberg und benennt die Ursachen für die erheblichen Unterschiede, die bei der Durchführung des GzVeN in diesen Ländern auszumachen sind.
Retrospective Analysis of Risk Factors for Periodic Limb Movements in a Large Cohort of Insomnia and Chronic Fatigue Patients
Authors: Tobback Els , Desmet Olivier , Hanoulle Ignace , Delesie Liesbeth , Pevernagie Dirk , Vogelaers Dirk , Mariman An
Published: August 2019

Introduction Although the pathophysiology of periodic limb movements in sleep (PLMS) is not well understood, there is increasing belief that management of PLMS can modulate humans’ general health. The aim of this study is to investigate the associations between risk factors including the use of antidepressants, hypnotics, and antihistamines as well as of caffeine, alcohol, and nicotine and the occurrence of PLMS and periodic limb movement disorder (PLMD).

Methods Patients with either chronic fatigue or insomnia who underwent polysomnography as standardized clinical assessment were included in a retrospective study. Associations were calculated between substance use and sleep variables.

Results Tricyclic antidepressants and serotonin and norepinephrine reuptake inhibitor (SNRI) are significantly associated with higher rates of PLMS. Additionally, SNRI is significantly positive associated with PLMD, as also seen for selective serotonin reuptake inhibitors (SSRI). The most frequently used SSRI escitalopram was significantly positively associated with PLMS and PLMD. A significantly negative association was found between paroxetine and PLMS. Benzodiazepines are negatively associated with PLMS and PLMD. Sedative antidepressants, antihistamines, and substance use are not associated with PLMS nor PLMD in this study.

Discussion This retrospective study adds supportive evidence to the association of drug classes with PLMS and PLMD. These findings may impact on clinical management of patients with a combined anxiety or mood disorder in need for these drug classes on the one hand and a significant sleep architecture disturbance through PLMS, potentially contributing to daytime symptoms, on the other hand.
Platinum-on-Carbon-Catalyzed Aqueous Oxidative Lactonization of Diols by Using Molecular Oxygen
Authors: Takakura Ryoya , Ban Kazuho , Sajiki Hironao , Sawama Yoshinari
Published: August 2019

A lactonization of various diols catalyzed by platinum on carbon (Pt/C) in water under an atmosphere of molecular oxygen was developed. Derivatives of 1,4- 1,5- and 1,6-diols were transformed into the corresponding five-, six-, and seven-membered lactones by the present oxidative lactonization method.
Dipeptide-Based Phosphonium Salt Catalysis: Application to Enantioselective Synthesis of Fused Tri- and Tetrasubstituted Aziridines
Authors: Wu Jia-Hong , Pan Jianke , Wang Tianli
Published: August 2019

Over the past decades, phase-transfer catalysis (PTC), generally based on numerous chiral quaternary ammonium salts, has been recognized as a powerful and versatile tool for organic synthesis in both industry and academia. In sharp contrast, PTC involving chiral phosphonium salts as the catalysts is insufficiently developed. Recently, our group realized the first enantioselective aza-Darzens reaction for preparing tri- and tetrasubstituted aziridine derivatives under bifunctional phosphonium salt catalysis. This article briefly discusses the recent development in asymmetric reactions (mainly including nucleophilic additions and cyclizations) promoted by chiral quaternary phosphonium salt catalysts. We expect that more catalytic asymmetric reactions will be developed on the basis of such new phase-transfer catalytic systems in the near future.
Evaluation of Fluoroscopic-Guided Closed Reduction versus Open Reduction of Sacroiliac Fracture-Luxations Stabilized with a Lag Screw
Authors: Rollins Amanda , Balfour Raviv , Szabo David , Chesvick Christina M.
Published: August 2019

Objective The aim of this study was to compare radiographic outcomes of open reduction versus fluoroscopic-guided closed reduction (FGCR) of sacroiliac fracture-luxations stabilized with a lag screw, as well as peri- and postoperative complications.

Study Design Medical records (2010–2015) and radiographs of dogs and cats diagnosed with sacroiliac fracture-luxation that underwent open reduction without fluoroscopic guidance (n = 24) or FGCR (n = 17) were retrospectively reviewed to assess sacroiliac fracture-luxation reduction and lag screw placement, and lag screw loosening on follow-up radiographs (range, 1–8 weeks postoperatively) when available. Peri- and postoperative complications were also recorded.

Results Optimal screw depth to sacral body width ratio (>60%) was achieved in a significantly higher proportion of FGCR cases than openly reduced fracture-luxations. A significantly lower rate of lag screw loosening was found for FGCR cases. Few peri- and postoperative complications were noted across both groups. Four out of 17 FGCR cases requiring conversion to an open approach were excluded from data analysis; they had a longer duration from trauma to surgical repair than the median duration from trauma to surgical repair for cases successfully reduced in closed fashion.

Conclusion Fluoroscopic-guided closed reduction of sacroiliac fracture-luxations leads to consistently more optimal screw placement, as well as a lower incidence of lag screw loosening on follow-up radiographs. However, for cases with a longer duration from trauma to surgical repair, one should be prepared to convert to an open approach if a closed approach is not amenable to adequate reduction and lag screw placement.
Pediatric Pancreaticobiliary Intervention
Authors: Giefer Matthew J. , Shivaram Giridhar M.
Published: August 2019

Advances in pediatric interventional radiologic and endoscopic techniques have increasingly allowed for a multidisciplinary approach toward diagnosis and management of pediatric pancreaticobiliary diseases. In the following sections, we describe clinical approaches to nontransplant pediatric pancreaticobiliary disease, established and novel pancreaticobiliary interventions, and logistical considerations of collaboration between pediatric interventional radiology and gastroenterology services.
Pituitary Apoplexy Causing Compression of Third Cranial Nerve—Management
Authors: Masopust Václav
Published: August 2019

Lesions of the oculomotor nerve as the first sign of pituitary adenoma are rare. The cause of such lesions without other clinical symptoms is discussed in this study. A small cohort of 4 patients (3.1%) with oculomotor nerve palsy (third nerve palsy) as the only neurologic deficit, from 129 patients who got operated upon for pituitary adenomas, is presented. In this group (mean age: 55 years, range: 36–65 years), all patients (two women and two men) underwent surgery. In two cases, there was arrested pneumatization and thickened bone. In the remaining two cases, a macroscopically visible, very solid opaque diaphragm was present, after the removal of the tumor and thickened bone. Complete adjustment was observed in all patients within 1 week after the surgery. Two factors that seem to increase the high risk for the development of oculomotor nerve palsy are that the cavernous sinus may be the only weak structure surrounding the sella turcica when the diaphragm and bone are thickened; and the rapid development of increased pressure in this region. The increased pressure on the cavernous sinus during the anatomical variations is the primary cause for lesions on the oculomotor nerve. However, this conjecture cannot be statistically demonstrated because of the small number of cases. Future research should be conducted on larger samples to increase statistical inference and generalizability.
Double-sided asymmetric surface modification of ZnO interfacial layer to enhance performance in organic solar cells
Authors: Liang Zhiqiang , Guan Tianfu , Zhang Qi , Shao Weijing , Chen Jianmei , Zheng Jianzhong , Li Dong , Abdulhalim Ibrahim , Jiang Lin
Published: August 2019

Surface modification of the widely used ZnO interfacial layer is a crucial issue for the development of photoelectric devices toward high efficiency and long-term stability. Most conventional surface modifications of ZnO interfacial layers involve only a one-sided modification (e.g., a ZnO/active layer interface), which limits the electrical and electronic performance of the resulting interfacial layer. Herein, we report a double-sided surface modification strategy in which both sides of the ZnO interfacial layer are modified. The resulting double-sided modified ZnO layers are used to enhance the photovoltaic performance of inverted organic solar cells as electron-transporting layers (ETLs). Compared with devices based on unmodified ZnO interfacial layers, the power conversion efficiencies of devices using the modified ZnO interfacial layer are markedly enhanced, from 3.42% to 4.23% for the P3HT:PC61BM active layer, and from 7.57% to 8.61% for the PTB7:PC71BM blend system. The enhancements in photovoltaic performance result mainly from the modified energy level alignment and improved interface contact quality between the ETL and active layer, which help to reduce the interfacial energy barrier between the active layer and indium tin oxide electrode, thereby enhancing the electron collection and transport efficiency. More importantly, this double-sided surface modification strategy could be easily extended to modify the interfacial layers of other photoelectric devices, such as perovskite solar cells, quantum dot solar cells and organic light-emitting diodes.
On self-similar solutions of the vortex filament equation
Authors: Gamayun O. , Lisovyy O.
Published: August 2019

We study self-similar solutions of the binormal curvature flow which governs the evolution of vortex filaments and is equivalent to the Landau-Lifshitz equation. The corresponding dynamics is described by the real solutions of the σ-Painlevé IV equation with two real parameters. Connection formulae for Painlevé IV transcendents allow for a complete characterization of the asymptotic properties of the curvature and torsion of the filament. We also provide compact hypergeometric expressions for self-similar solutions corresponding to corner initial conditions.
Magnetic-field-induced ferroelectric domain dynamics and in-plane polarization in odd and mixed layered Aurivillius structures
Authors: Faraz Ahmad , Arif Suneela
Published: August 2019

Herein, we conclusively discovered the role of “2D” odd/mixed, layered Aurivillius structures in generating coupled order parameters by directly visualizing magnetic-field-induced ferroelectric switching. We developed a novel sequence liquid injection-chemical vapor deposition process to fabricate atomistically controlled layer-by-layer genuine multiferroic Bi6Ti2.9Fe1.5Mn0.6O18 and Bi6Ti2.7Fe1.5Mn0.8O18 thin films. Ferromagnetic signature (MS = 13.79 emu/cc, HC = 9 mT at 300 K, and MR = 8 emu/cc) was generated for Bi6Ti2.9Fe1.5Mn0.6O18 thin films; however, no response was observed for mixed m = 5/6 intergrowths in Bi6Ti2.7Fe1.5Mn0.8O18 films. In-plane PR with magnetic (Fe/Ti)/conducting (Au/Ti) for Bi6Ti2.9Fe1.5Mn0.6O18 thin films is less (±23.66–24.69 μC/cm2) than the mixed m = 5/6 Bi6Ti2.7Fe1.5Mn0.8O18 layer structure (±57.42–67.94 μC/cm2). High leakage current for Fe/Ti interdigital capacitors (IDCs) compared to Au/Ti IDCs samples confirms Au/Ti IDCs’ suitability for ferroelectric industry. High ferro-paraelectric transition (Tc = 850 K), excellent in-plane polarization with negligible fatigue (9% after 1010 switching cycles), and coupled magnetoelectric (ME) (10% in-plane and 13% out-of-plane) orders provide an important contribution in a high-temperature fatigue free nonvolatile in-plane FeRAM, 4-state logics, and ME sensors.

This article is being retracted effective 16 November 2020.
Metalorganic vapor phase epitaxy growth and characterization of quaternary (Ga,In)(As,Bi) on GaAs substrates
Authors: Hepp Thilo , Maßmeyer Oliver , Duffy Dominic A. , Sweeney Stephen J. , Volz Kerstin
Published: August 2019

The incorporation of dilute amounts of Bi into the host lattice of a III/V semiconductor has a strong influence on its electronic properties. The bandgap is strongly redshifted which makes these materials interesting for application in the near- to mid-infrared regime. Furthermore, the spin-orbit splitting is increased resulting in suppression of hot-hole producing Auger recombination, which makes the fabrication of highly efficient optical devices feasible. However, for ternary Ga(As,Bi) grown using metalorganic vapor phase epitaxy (MOVPE), it has proven difficult to achieve the desired composition of the ternary material. Therefore, the additional incorporation of indium (In) into Ga(As,Bi), which should induce a further redshift of the bandgap, is investigated and summarized in this paper. For deposition of quaternary (Ga,In)(As,Bi), two different low temperature growth techniques using MOVPE are conducted. The strain and photoluminescence peak positions of the samples are correlated to estimate the composition of the (Ga,In)(As,Bi) layers. It was found that the trimethylindium and tertiarybutylarsine supplies need to be carefully adjusted to grow high quality bulk materials and that the incorporation of indium is inversely related to the amount of incorporated Bi.
Improved optical properties of InAs submonolayer quantum dots in GaAsSb/InGaAs double-well structure
Authors: Liu Wei-Sheng , Yang Ting-Kai , Hsueh Wei-Jen , Chyi Jen-Inn , Huang Tien-Yuan , Hsu Ming-En
Published: August 2019

In this study, multistacked InAs submonolayer (SML) quantum dots (QDs) were sandwiched in an InGaAs/GaAsSb dot-in-a-double-well (DDwell) structure to enhance the crystal quality and optical properties of QDs. The photoluminescence (PL) intensity of the InAs SML QDs with the DDwell structure was 5.5 times higher than that of conventional InAs/GaAs SML QDs because of the reduced number of nonradiative recombination centers and the enhanced carrier hole confinement. The PL results of the DDwell structure exhibit two peaks that represent the carrier overflow from SML QDs to InGaAs quantum wells (QWs) and hence the radiative recombination in InGaAs QWs because of the shallow carrier confinement of SML QDs. Among the compared samples, the DDwell structure exhibited the highest activation energy of 101.8 meV. Furthermore, the carrier thermal escape was suppressed in these InAs SML QDs. High-resolution transmission electron microscopy revealed that the microstructures of the InAs SML QDs demonstrated larger dots for the DDwell structure, thus verifying that the emission wavelength elongated in the PL measurement. These improved optical properties of the InAs SML QDs with the DDwell structure were attributable to the improved crystal quality because of the use of Sb surfactants and additional volume for carrier recombination provided by the InGaAs quantum well. The DDwell structure can thus be applied in optoelectronic devices to obtain advanced performance.
Effect of co-sintering time on magnetoelectric response of Pb0.895Sr0.06La0.03(Zr0.56,Ti0.44)O3 multilayer–Ni0.6Zn0.4Fe2O4 composite fabricated by tape casting
Authors: S Premkumar , Mathe V. L.
Published: August 2019

The effect of cosintering time on magnetoelectric (ME) behavior of Sr, La doped lead zirconate titanate multilayer–nickel zinc ferrite composites fabricated by the tape-casting method has been investigated. Powders of individual phases, viz., Pb(1 − x − 3y/2)SrxLay(Zrz,Ti(1 − z))O3 (PSLZT) and Ni0.6Zn0.4Fe2O4 (NZFO), were prepared by the solid-state reaction method, and their respective thick films were fabricated by the tape-casting method. A PSLZT multilayer having Pt inner electrodes stacked onto NZFO laminated composites was cosintered at 1060 °C for 1–10 h. Cosintered, warpage-free, and delamination-free layered composite thick film structures were analyzed by scanning electron microscopy. Microstructure at the interface could be crucial for better magnetoelectric coupling, and, hence, the microstructure of the interface was analyzed as a function of sintering time at a fixed sintering temperature. Elemental mapping revealed a negligible interdiffusion between PSLZT and NZFO phases. Composites cosintered for different time durations were analyzed for their ferroelectric behavior. Further, impedance spectrum analysis indicated clear resonance behavior for the composites cosintered for 2 and 6 h. All the composites were analyzed for magnetoelectric properties at different applied DC magnetic fields having a superimposed ac magnetic field of a fixed frequency and different ac frequencies at fixed DC magnetic fields. The magnetoelectric coefficient was found to increase with an increase in the sintering time of up to 6 h and an ME coefficient of 230 mV/cm Oe with a self-bias nature. Magnetoelectric resonance behavior was also studied, which showed an ME voltage coefficient of 6 V/cm Oe for composites sintered for 6 h at resonance.
Nearshore natural convection induced by a periodic thermal forcing at the water surface
Authors: Mao Yadan
Published: August 2019

Field observations reveal that under calm weather conditions, natural convection resulting from spatial variations in the temperature field plays a significant role in promoting exchanges and mixings in lakes and reservoirs. The present investigation is concerned with natural convection generated by a periodically varying surface temperature within a reservoir model consisting of a sloping nearshore section and a flat offshore section. Three approaches, including derivation of analytical solution, numerical simulation, and scaling analysis, are integrated to reveal the variation of flow response with the intensity of the thermal forcing. The analytical solution reveals that for a sinusoidally varying surface temperature, a cosinusoidally varying surface heat flux is imposed if the duration of the period is sufficiently long. Numerical results show dramatic differences in flow response between conduction-dominated and convection-dominated thermal flow. The former is in phase with the cosinusoidal variation of surface heat flux, whereas the latter is in phase with the sinusoidal variation of surface temperature. The thermal forcing for conduction-dominated and convection-dominated flow is prescribed by surface heat flux and surface temperature, respectively. An evident phase lag is observed shortly after the thermal forcing switches sign. For convection-dominated flow with a Rayleigh number of 2 × 107, the maximum velocity during the cooling phase is significantly larger than that during the heating phase owing to the occurrence of flow instability during the cooling phase, which agrees with field observations. The scales for flow velocity and phase lag are derived by scaling analysis and verified by the results of numerical simulations.
Effects of nanoepitaxial lateral overgrowth on growth of
α
-Ga2O3 by halide vapor phase epitaxy
Authors: Cha An-Na , Bang Seungwan , Rho Hokyun , Bae Hyojung , Jeon Dae-Woo , Ju Jin-Woo , Hong Soon-Ku , Ha Jun-Seok
Published: August 2019

We demonstrate that Pd nanoparticle/single-walled carbon nanotubes (Pd-SWCNTs) can be used to improve the quality of α-Ga2O3 crystals using halide vapor phase epitaxy (HVPE) methods. We employed Pd-SWCNTs as the nanoepitaxial lateral overgrowth (ELOG) mask instead of typical dielectric microsize materials, such as SiNx or SiO2. Nano-ELOG Pd-SWCNTs were deposited on a (0001) buffer layer using nanospray coating. Cs-corrected TEM (transmission electron microscopy) analysis revealed that the crystal quality of regrown α-Ga2O3 improved owing to both the blocking of dislocations by the nano-ELOG in the Pd NPs and the dislocation bending by the inclined facets. This simple yet effective technique is believed to be applicable to various growth systems and will find diverse applications in other crystal growth processes.
Plasmonic visible-NIR photodetector based on hot electrons extracted from nanostructured titanium nitride
Authors: Podder Santanu , Pal Arup R.
Published: August 2019

The superior plasmonic characteristics of transition metal nitrides have been widely considered for enhancing the performance of light-harvesting devices. We explore this fast-emerging field further and report here the successful implementation of titanium nitride (TiN) nanoparticles prepared by reactive magnetron sputtering in a broadband photodetector device geometry. X-Ray Photoelectron Spectroscopy study reveals the presence of two different phases, viz., titanium nitride and titanium oxynitride in the prepared TiN sample. These two different nitride phases lead to two plasmon absorption bands, one in the visible region and the other in the Near Infrared (NIR) region of the electromagnetic spectrum, which is a fascinating finding of this study. The fabricated photodetector shows appreciable photoelectrical response in the visible as well as in the NIR region due to plasmon induced charge separation aided by the TiN nanoparticles. Very high photoresponsivities of 158 mA/W and 230 mA/W of the device at wavelengths of 450 nm and 950 nm, respectively, make it very promising as a broadband photodetector. The corresponding Internal Quantum Efficiencies are found to be 48% and 35%, respectively, at those two particular wavelengths. The charge transport mechanism of the device is explained with an energy level diagram, which shows that the hot electrons produced from the decay of plasmon are responsible for the generation of photocurrent.
Fabrication, characterization, and application-matched design of thermoelectric modules based on Half-Heusler FeNbSb and TiNiSn
Authors: Landmann Daniel , Tang Yinglu , Kunz Benjamin , Huber Renato , Widner Daniel , Rickhaus Peter , Widmer Remo N. , Elsener Hans Rudolf , Battaglia Corsin
Published: August 2019

We describe the fabrication of thermoelectric modules based on Half-Heusler TiNiSn and FeNbSb and their performance assessment under different boundary conditions. Module design is guided by a multiphysics model implementing experimentally determined thermoelectric materials properties. We consider two types of boundary conditions: first, imposing fixed cold- and hot-side temperatures onto the module, and second, imposing fixed values for the heat transfer coefficients between module and heat sink and source, representative for a waste-heat-recovery system using the exhaust heat of an internal combustion engine. We compare the modeling results with experimental data obtained from Half-Heusler modules integrated into a heat exchanger mounted to the exhaust of a compact van.
Full-field flow measurement in evaporating sessile droplets based on the Scheimpflug principle
Authors: Zhao Haoyang , Wang Tianyou , Che Zhizhao
Published: August 2019

The direct visualization of flow fields plays an important role in droplet evaporation. However, the refraction of light at the curved droplet surface makes it challenging to obtain the accurate flow field. To solve this problem in evaporating sessile droplets, a full-field flow visualization measurement employing the Scheimpflug principle is proposed and a mapping method to eliminate the perspective effects on the particle image velocimetry results is introduced. Compared with the distorted images captured from the side of the droplet, the proposed method can improve the measurement accuracy significantly and the flow details near the droplet surface can be obtained.
Detection of electron spin resonance via magnetoimpedance in La1−xCaxMnO3
Authors: Chaudhuri Ushnish , Mahendiran R.
Published: August 2019

We demonstrate a method to detect the spin resonance of Mn electrons at room temperature in paramagnetic samples of La1−xCaxMnO3 with x = 0.35, 0.40, and 0.45 using a simple magnetoimpedance (MI) measurement. The magnetic field dependent “ac” resistance and reactance were simultaneously measured at 300 K using a single-port impedance analyzer by passing a current of frequency f = 500 MHz–3 GHz directly through the sample. The magnetoresistance of each sample increased abruptly at a critical value of the applied magnetic field while the magnetoreactance displayed a dip. Both these features shifted linearly toward higher “dc” magnetic fields with increasing frequency of the current. We suggest that these anomalies in MI are imprints of spin resonance from the Mn electrons. Our results were also verified using a conventional broadband spectrometer (f = 2–10 GHz). Thus, the electrical detection of paramagnetic resonance using a low-cost impedance analyzer, as demonstrated here, can provide an alternate method to investigate magnetic resonances in various materials.
Anisotropic energy transfers in rapidly rotating turbulence
Authors: Sharma Manohar K. , Verma Mahendra K. , Chakraborty Sagar
Published: August 2019

We perform direct numerical simulations and analyze the ring-to-ring energy transfer in the three-dimensional hydrodynamic turbulence rendered anisotropic by rapid rotation. The rotation rate is taken to be so high that the Zeman scale is well beyond the Kolmogorov dissipation scale. Our main result is that, while the anisotropic transfer of energy is equatorward in the case of the decaying rotating turbulence, in the case of the forced rotating turbulence, the transfer is equatorward only for the scales larger than the forcing scale and poleward for the smaller scales. We also discuss in detail how our results are at odds with the corresponding results for the analogous magnetohydrodynamic turbulence.
Scaling of the free and the relaxed exciton in perovskites (RNH3)2(CH3NH3)p−1PbpI3p+1 large sized monolayers
Authors: Zahra Haitham , Ayari Sabrine , Jaziri Sihem
Published: August 2019

The investigation of the fluctuations and their influence on the exciton in the perovskite structure is topical. These fluctuations can be due to the prolongation of the annealing or the increasing of the temperature in the perovskite monolayers. This fact generates structural imperfections, which may arise from vacancies and lattice structural defects. In this work, we propose a theoretical approach in order to study the optical properties characterized by excitons in (RNH3)2(CH3NH3)p−1PbpI3p+1 perovskite structures. For high quality samples, we investigate the free exciton taking into account the quantum and the dielectric confinements. For low quality samples, we model the surface disorder of perovskite monolayers through a randomized potential in the layer plane. Finally, we investigate the dependence of the perovskite layer thickness (p-value) on the shift between the relaxed exciton compared to the free exciton, and we show that our model allows us to simulate the experimental spectra of the exciton states.
First principles investigation of Y2O3-doped HfO2
Authors: Padilha A. C. M. , McKenna K. P.
Published: August 2019

First-principles calculations based on a truncated Coulomb hybrid functional were used to elucidate Y2O3 doping of HfO2. We calculated the formation enthalpies as well as density of states of nearly 1200 defective structures of two phases of HfO2: room-temperature monoclinic and high-temperature cubic structures. For dilute doping, the monoclinic phase is retained and electron trapping states are introduced near the conduction band minimum. For doping concentrations near to 12.5 at. %, the cubic phase is stabilized and the gap is free from charge trapping defect states, making it a suitable high-dielectric constant material for complementary metal-oxide semiconductor applications.
Molecular dependencies of dynamic stiffening and strengthening through high strain rate microparticle impact of polyurethane and polyurea elastomers
Authors: Sun Yuchen , Wu You-Chi Mason , Veysset David , Kooi Steven E. , Hu Weiguo , Swager Timothy M. , Nelson Keith A. , Hsieh Alex J.
Published: August 2019

This study investigates the molecular dependencies of dynamic stiffening and strengthening through comparison of high strain rate impact responses of various polyurethanes and polyureas. We use an in-house designed tabletop microimpact experimental platform—the laser-induced particle impact test—to perform high strain rate impacts and measure the corresponding material response. Dynamic mechanical analysis and differential scanning calorimetry are used to show that glass transition temperature is a useful predictor of the impact response at ambient temperatures. Meanwhile, solid-state nuclear magnetic resonance spectroscopy identifies segmental dynamics as an important determinant of the variation in both dynamic stiffening and strengthening. The impact responses of polyurethanes and polyureas both show clear dependencies on the molecular weight of the soft segment. This comparison suggests the state of intermolecular hydrogen bonding plays a key role in dynamic stiffening and strengthening. This study aims to identify the molecular dependencies of the impact response and establish a foundation for further design and testing of optimal high strain rate characteristics in synthetic elastomers.
Thermoelectric properties of non-stoichiometric Cu2+xSn1−xS3 compounds
Authors: Deng Tingting , Qiu Pengfei , Song Qingfeng , Chen Hongyi , Wei Tian-Ran , Xi Lili , Shi Xun , Chen Lidong
Published: August 2019

Diamondlike compound Cu2SnS3 has attracted great attention recently due to its excellent thermoelectric performance and the features of being eco-friendly and low cost. However, the underlying mechanism for its good electrical transports under high carrier concentration range is still not clear. In this work, we synthesized a series of Cu2+xSn1−xS3 (x = 0–0.08) samples. These nonstoichiometric Cu2+xSn1−xS3 samples are polymorph simultaneously crystalizing in the monoclinic, tetragonal, and cubic structures. The characterization on the electrical transports and the analysis on the band structure reveal that the large density-of-states effective mass, high Seebeck coefficient, and high mobility under a high carrier concentration in the Cu2+xSn1−xS3 system are originated from the existence of multiple bands near the edge of the valence band. Likewise, the polymorphic structure has little influence on the electrical transports. A maximum power factor of 12.6 μW cm−1 K−2 at 700 K has been obtained for the nonstoichiometric Cu2.08Sn0.92S3. Combining the low lattice thermal conductivity of these samples, Cu2.08Sn0.92S3 shows a peak dimensionless figure of merit of 0.5 at 700 K. This work is helpful for guiding the future optimization of thermoelectric performance on Cu2SnS3.
Spontaneous polarization enhancement in ferroelectric Hf0.5Zr0.5O2 using atomic oxygen defects engineering: An ab initio study
Authors: Wei Wei , Ma Xiaolei , Wu Jixuan , Wang Fei , Zhan Xuepeng , Li Yuan , Chen Jiezhi
Published: August 2019

Oxygen defect impacts on ferroelectricity in Hf0.5Zr0.5O2 (HZO) are systematically studied on the basis of first-principles calculations. Importantly, the oxygen vacancy and Frenkel pair could enhance the spontaneous polarization (Ps) by an average of 14.5%, while Oi could largely reduce Ps of HZO by 44.8% on the contrary. The altered Ps and, accordingly, the remanent polarization (Pr) agree well with the experimental results of polarization variability. Oxygen vacancy induced Pr enlargement is revealed to be the underlying mechanism responsible for the wake-up effect. Our results provide a guideline to boost the ferroelectricity via defect engineering in ferroelectric HZO.
Frequency-independent breakdown strength of dielectric elastomers under AC stress
Authors: Iannarelli A. , Ghaffarian Niasar M. , Ross Rob
Published: August 2019

Soft insulators are the main component used in dielectric elastomer actuators (DEAs). It follows that dielectric properties like permittivity and dielectric strength of the insulator can strongly influence the maximum dynamic actuation performance of DEA devices. We observed an increasing breakdown voltage with increasing driving AC voltage frequency for silicone-based dielectric films. Despite the breakdown voltage increase, we demonstrate that there is no actual breakdown electric field rise with varying frequencies. We show that the voltage behavior is rather compatible with a constant dielectric breakdown field model and the slow mechanical response of the elastomer.