bluuebunny/crossref_metadata_2025 huggingface dataset:
Contemporary Synthetic Strategies towards Secosteroids, abeo-Steroids, and Related Triterpenes
Authors: Noack Florian , Heinze Robert , Heretsch Philipp
Published: April 2019

Steroids have long been sought after as synthetic targets. Their rearranged counterparts, though, have only recently received more attention, when isolation and biological testing programs revealed several molecular entities that were both structurally intriguing as well as biologically relevant. This review will highlight contemporary synthetic approaches towards the growing class of seco- and abeo-steroids and some related triterpenoid natural products.

1 Introduction

2 Cyclocitrinol

2.1 Li’s Synthesis of Cyclocitrinol

2.2 Gui’s Synthesis of Cyclocitrinol

3 Strophasterol

3.1 Heretsch’s Synthesis of Strophasterol A

3.2 Kuwahara’s Synthesis of Strophasterols A and B

4 Pleurocin A/Matsutakone and Pleurocin B

4.1 Heretsch’s Synthesis of Pleurocin A/Matsutakone and Pleurocin B

5 Aplysiasecosterol A

5.1 Li’s Synthesis of Aplysiasecosterol A

6 Glaucogenins C and D

6.1 Tian’s Syntheses of 5,6-Dihydro-glaucogenin C and Glaucogenin D

7 Physalin B

7.1 Sodeoka’s Synthesis of the DFGH Ring System of Physalin B

8 Limonin

8.1 Hirama’s Synthesis of (±)-Limonin

9 Schiglautone A

9.1 Ding’s Synthesis of (±)-atrop-Schiglautone A

10 Conclusion
Intermolecular Trapping of Alkoxyl Radicals with Alkenes: A New Route to Ether Synthesis
Authors: Barthelemy Anne-Laure , Tuccio Béatrice , Magnier Emmanuel , Dagousset Guillaume
Published: April 2019

Alkoxyl radicals are highly reactive species which rapidly react by hydrogen atom transfer (HAT) or β-fragmentation to afford a carbon-centered radical. We discuss herein how these RO· radicals can be efficiently trapped in an intermolecular manner by styrene derivatives when they are generated by photoredox catalysis from the corresponding N-alkoxypyridinium salts. This allows for the synthesis of valuable ethers with complete anti-Markovnikov regioselectivity.

1 Introduction

2 Anti-Markovnikov Alkoxylation of Alkenes: Background

3 Addition of Alkoxyl Radicals to Styrenes

4 Summary and Outlook
Formamide Catalysis Facilitates the Transformation of Aldehydes into Geminal Dichlorides
Authors: Huy Peter Helmut
Published: April 2019

Herein, a novel method for the transformation of aldehydes into geminal dichlorides based on phthaloyl chloride as reagent and N-formylpyrrolidine as Lewis base catalyst is disclosed. Given the mild reaction conditions, the current protocol is distinguished by high levels of functional group compatibility and scalability and is operationally simple. The in situ formation of a Vilsmeier Haack reagent type intermediate is likely to be essential for this organocatalytic nucleophilic substitution reaction.
Variables Associated with Endometriosis-related Pain: A Pilot Study using a Visual Analogue Scale
Authors: Cozzolino Mauro , Coccia Maria Elisabetta , Lazzeri Giacomo , Basile Francesca , Troiano Gianmarco
Published: April 2019

Objective Endometriosis is a complex disease, and pain is an important component of the syndrome. One of the most used methods to assess pain is the visual analogue scale (VAS). The aim of the present research was to study the pain experienced by patients who referred to our unit for endometriosis, using the VAS to understand the variables that could influence it.

Methods We have conducted a prospective study from February 2012 to December 2016, enrolling 388 patients who referred to a university hospital, in Florence, Italy. We have included in the present study patients during their follow-up for endometriosis; we have also included patients who underwent surgery with a histological diagnosis of endometriosis. We have collected sociodemographic and clinical information regarding age, body mass index (BMI), smoking habit, number of pregnancies, and endometriosis staging. Finally, we have administered the VAS for several symptoms.

Results Dysmenorrhea was the symptom associated with the highest perception of pain (mean VAS score of 5.76). The logistic regression showed that the stage of endometriosis could influence the pain associated to constipation and to dysuria. The linear regression showed that age could influence the pain associated to constipation, to dyspareunia, and to dysmenorrhea. A positive correlation was found between dysmenorrhea and chronic pelvic pain (CPP), between dysmenorrhea and dyspareunia, and between constipation and dysuria.

Conclusion Using a validated method, the VAS, we have studied the pain experienced by a group of patients with a history of endometriosis and observed that smoking habit and BMI did not influence the VAS scores, and that dysmenorrhea was associated with the highest perception of pain.
Adaptive Proximal Scaphoid Implant: Indications and Long-Term Results
Authors: Poumellec Marie-Anne , Camuzard Olivier , Pequignot Jean-Pierre , Dreant Nicolas
Published: April 2019

Objective This study aims to define the indications of APSI and to evaluate the long-term results.

Patients and Methods This is a monocentric study including patients that underwent an arthroplasty of the scaphoid proximal pole using an APSI between 1994 and 2010. Patients were assessed using autoquestionnaires and measuring ranges of motion, key pinch, and grip strength. X-ray views of the wrist were done to control the mobility of the implant and the evolution of the carpal collapse, if present.

Results There were 19 patients included with a mean follow-up of 11 years. The mean range of motion was 106 degrees (65% of contralateral side) in flexion-extension and 33 degrees (78% of contralateral side) in radialulnar deviation. The mean grip strength was 72% of the contralateral side. The mean Mayo wrist score was 69/100, the mean QuickDASH 26/100, and the mean patient-rated wrist evaluation (PRWE) 25/100. After 10 years, evolution to osteoarthritis was noted in 32% of the patients. This was associated with a decrease of the carpal height. More specifically, capito-lunate osteoarthritis was noted after 10 years and two out of three patients were concerned after 20 years of follow-up. No osteoarthritis was diagnosed at the radiolunate articulation.

Conclusion APSI is a treatment option that enables patients with scaphoid nonunion advanced collapse (SNAC), scapholunate advanced collapse (SLAC) I or II to preserve the strength and mobility with good functional results. But this arthroplasty does not prevent natural evolution to a carpal collapse after a follow-up of 20 years which is clinically well tolerated.
Clinical Features and Management of Women with Borderline Ovarian Tumors in a Single Center in Brazil
Authors: Yoshida Adriana , Tavares Bárbara Virginia Gonçalves , Sarian Luís Otavio , Andrade Liliana Aparecida Lucci Ângelo , Derchain Sophie Françoise
Published: April 2019

Objective The aim of the present study was to describe and analyze data of 57 women with borderline ovarian tumors (BOTs) regarding histological characteristics, clinical features and treatment management at the Department of Obstetrics and Gynecology of the Universidade Estadual de Campinas (Unicamp, in the Portuguese acronym).

Methods The present retrospective study analyzed data obtained from clinical and histopathological reports of women with BOTs treated in a single cancer center between 2010 and 2018.

Results A total of 57 women were included, with a mean age of 48.42 years old (15.43–80.77), of which 30 (52.63%) were postmenopausal, and 18 (31.58%) were < 40 years old. All of the women underwent surgery. A total of 37 women (64.91%) were submitted to complete surgical staging for BOT, and none (0/57) were submitted to pelvic or paraortic lymphadenectomy. Chemotherapy was administered for two patients who recurred. The final histological diagnoses were: serous in 20 (35.09%) cases, mucinous in 26 (45.61%), seromucinous in 10 (17.54%), and endometrioid in 1 (1.75%) case. Intraoperative analyses of frozen sections were obtained in 42 (73.68%) women, of which 28 (66.67%) matched with the final diagnosis. The mean follow-up was of 42.79 months (range: 2.03–104.87 months). Regarding the current status of the women, 45 (78.95%) are alive without disease, 2 (3.51%) are alive with disease, 9 (15.79%) had their last follow-up visit > 1 year before the performance of the present study but are alive, and 1 patient (1.75%) died of another cause.

Conclusion Women in the present study were treated according to the current guidelines and only two patients recurred.
The Lebanese Allele in the PET100 Gene: Report on Two New Families with Cytochrome c Oxidase Deficiency
Authors: Mansour Hicham , Sabbagh Sandra , Bizzari Sami , El-Hayek Stephany , Chouery Eliane , Gambarini Alicia , Gencik Martin , Mégarbané André
Published: April 2019

Cytochrome c oxidase deficiency is caused by mutations in any of at least 30 mitochondrial and nuclear genes involved in mitochondrial complex IV biogenesis and structure, including the recently identified PET100 gene. Here, we report two families, of which one is consanguineous, with two affected siblings each. In one family, the siblings presented with developmental delay, seizures, lactic acidosis, abnormal brain magnetic resonance imaging, and low muscle mitochondrial complex IV activity at 30%. In the other family, the two siblings, now deceased, had a history of global developmental delay, failure to thrive, muscular hypotonia, seizures, developmental regression, respiratory insufficiency, and lactic acidosis. By whole exome sequencing, a missense mutation in exon 1 of the PET100 gene (c.3G > C; [p.Met1?]) was identified in both families. A review of the clinical description and literature is discussed, highlighting the importance of this variant in the Lebanese population.
Effects of MTNR1B Genetic Variants on Individual Susceptibility to Gestational Diabetes Mellitus: A Meta-Analysis
Authors: Jia Guangliang , Gao Yanxiang , Li Chunzhi , Zhang Yanqin
Published: April 2019

Objective Whether melatonin receptor 1B (MTNR1B) variants are implicated in gestational diabetes mellitus (GDM) remains unclear. Therefore, we performed this meta-analysis to obtain a more conclusive result on associations between MTNR1B variants and GDM.

Study Design Literature research was performed in PubMed, Web of Science, Embase, and China National Knowledge Infrastructure. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

Results A total of 17 studies were eligible for analyses. Pooled overall analyses showed that rs1387153 (dominant model: p = 0.0002, OR = 0.78, 95% CI: 0.68–0.89; recessive model: p < 0.0001, OR = 1.46, 95% CI: 1.24–1.73; allele model: p < 0.0001, OR = 0.78, 95% CI: 0.72–0.84), rs4753426 (recessive model: p = 0.01, OR = 1.75, 95% CI: 1.14–2.68; allele model: p = 0.01, OR = 0.69, 95% CI: 0.51–0.93), and rs10830963 (dominant model: p < 0.0001, OR = 0.72, 95% CI: 0.65–0.78; recessive model: p < 0.0001, OR = 1.56, 95% CI: 1.40–1.74; allele model: p < 0.0001, OR = 0.73, 95% CI: 0.69–0.78) variants were all significantly associated with the susceptibility to GDM. Further subgroup analyses by ethnicity of participants yielded similar positive results.

Conclusion Our findings indicated that MTNR1B rs1387153, rs4753426, and rs10830963 variants might serve as genetic biomarkers of GDM.
Surgical Treatment of Bilateral Lung Cancers: Long-Term Outcomes and Prognostic Factors
Authors: Petrella Francesco , Frassoni Samuele , Bagnardi Vincenzo , Casiraghi Monica , Brambilla Daniela , Diotti Cristina , Spaggiari Lorenzo
Published: April 2019

Background Bilateral lung neoplasms are becoming more common, but distinguishing two primary lung cancers from metastatic disease can be difficult and only long-term follow-up after treatment can disclose the real behavior of the disease.

The present study aimed to identify the appropriate candidates for bilateral surgical resections from the perspective of short-term postoperative complications and long-term outcomes.

Methods Two hundred and fifteen consecutive patients undergoing bilateral pulmonary resection for lung cancers over a 20-year period were analyzed. Preoperative patient characteristics were noted, including demographic information, operative details, pathologic information including histology and tumor stage according to the eighth edition of the tumor nodes metastases staging system, and the use of neoadjuvant or adjuvant treatments.

Results Patients receiving the second pulmonary resection more than 24 months from the first procedure as well as patients receiving bilateral lobectomies had higher overall 3-, 5-, and 10-year survival rates compared with the others.

Conclusion Patients receiving the second resection more than 24 months from the first procedure have the best long-term results irrespective of the type of resection.
Modules of highest weight type for the algebra of derivations over a rational quantum torus
Authors: Xu Chengkang , Luo Wenqi , Zhang Fen
Published: April 2019

For the Lie algebra of derivations over a rational quantum torus, we construct a class of irreducible weight modules with all finite dimensional weight spaces, which are called the modules of highest weight type, generating the notion for the case of commutative torus.
Comment on “Effective of the q-deformed pseudoscalar magnetic field on the charge carriers in graphene” [J. Math. Phys. 57, 082105 (2016)]
Authors: Obispo Angel E. , B. Freitas Gisele , B. Castro Luis
Published: April 2019

We point out a misleading treatment in a recent paper published in this journal [M. Eshgi and H. Mehraban, J. Math. Phys. 57, 082105 (2016)] concerning solutions for the two-dimensional Dirac-Weyl equation with a q-deformed pseudoscalar magnetic barrier. The authors misunderstood the full meaning of the potential and made erroneous calculations, and this fact jeopardizes the main results in this system.
Existence of positive solution to Kirchhoff-Schrödinger-Poisson system with strong singular term
Authors: Zhang Qi
Published: April 2019

In this paper, we consider the existence of positive solution to the Kirchhoff-Schrödinger-Poisson system with strong singularity. By using the variational method, the necessary and sufficient condition for the existence of a solution is obtained.
Uniformization techniques for stochastic simulation of chemical reaction networks
Authors: Beentjes Casper H. L. , Baker Ruth E.
Published: April 2019

This work considers the method of uniformization for continuous-time Markov chains in the context of chemical reaction networks. Previous work in the literature has shown that uniformization can be beneficial in the context of time-inhomogeneous models, such as chemical reaction networks incorporating extrinsic noise. This paper lays focus on the understanding of uniformization from the viewpoint of sample paths of chemical reaction networks. In particular, an efficient pathwise stochastic simulation algorithm for time-homogeneous models is presented which is complexity-wise equal to Gillespie’s direct method. This new approach therefore enlarges the class of problems for which the uniformization approach forms a computationally attractive choice. Furthermore, as a new application of the uniformization method, we provide a novel variance reduction method for (raw) moment estimators of chemical reaction networks based upon the combination of stratification and uniformization.
A control strategy for hybrid energy storage based on double-layer fuzzy controller integrated with second-ahead control thought
Authors: Liu Lijun , Da Chao , Zhou Wang , Wang Mengqi
Published: April 2019

With the continuous increase in the penetration of renewable energy resources, such as wind power, into power grids, fluctuations in power output introduce significant challenges to the power grid's safe and reliable operation. The hybridization of energy storage technologies effectively stabilizes fluctuations from wind power. This paper proposes a hybrid energy storage control strategy based on an adaptive wavelet decomposition and fuzzy control theory. Firstly, to meet the fluctuation requirements for the power output from wind farms, a wavelet packet decomposition approach is used to determine the grid-connected wind power and power allocation for different energy storage techniques by considering the power output characteristics and lifecycles. Secondly, the use of prediction results from the energy storage power output combined with a two-layer fuzzy controller enables advanced control of the energy storage system and optimal operation of the power output for different types of energy storage systems. The results show that the proposed strategy can effectively be applied to suppress the second-level wind power fluctuations and allocate the output of the hybrid energy storage system. Furthermore, this approach eliminates possible limit violation phenomena while operating the energy storage device to achieve optimal coordination for different energy storage systems considering the lifecycles of the energy storage device.
Investigation of the argon temperature modes in ICP-processing of glass-ceramics
Authors: Gafarov Ildar , Tovstopyat Alexander , Galeev Vadim , Golyaeva Anastasia , Golyaev Yuri , Kuznetsov Evgeny
Published: April 2019

Thermal modes of the argon inductively coupled plasma stream (13.56 MHz) were investigated with the respect to macroscopic parameters. The pressure in the vacuum chamber was varied from 10 to 80 Pa and the RF generator power from 500 to 2500 W. Thus, the radial temperature distribution in the stream was studied at different distances from the plasma torch. It was established that the temperature of the plasma-forming gas can reach 800 °C at the center of the stream and smoothly decreases to the periphery. Specific heat capacity and the heating rate of a two-phase, SiO2 based, glass-ceramic material were investigated in the plasma stream with different plasma parameters.
The counterdiffusion of HCl and NH3: An experimental and modeling analysis of topochemistry, diffusion, reaction, and phase transitions
Authors: Thompson Stephen , Shipman Patrick D. , Shipman Stephen P. , Zurlinden Todd J.
Published: April 2019

Vapor-phase ammonia, NH3(g), and hydrochloric acid, HCl(g), undergo a series of complex reactions, including nucleation and growth, to form solid ammonium chloride, NH4Cl(s). The counterdiffusional experiment, whereby HCl(g) and NH3(g) diffuse from opposite ends of a tube and react to form spatiotemporally complex patterns, has a rich history of study. In this paper, we combine experimental data, molecular simulations, and analysis and simulations of a partial differential equation model to address the questions of where the first unobserved vapor product NH4Cl(g) and visually observable precipitate NH4Cl(s) form and how these positions depend on experimental parameters. These analyses yield a consistent picture which involves a moving reaction front as well as previously unobserved heterogeneous nucleation, wall nucleation, and homogeneous nucleation. The experiments combined with modeling allow for an estimate of the heterogeneous and homogeneous nucleation thresholds for the vapor-to-solid phase transition. The results, synthesized with the literature on this vapor-to-particle reaction, inform a discussion of the details of the reaction mechanism, including the role of water, which concludes the paper.
MBE growth strategy and optimization of GaAsBi quantum well light emitting structure beyond 1.2 μm
Authors: Pan Wenwu , Wang Lijuan , Zhang Yanchao , Lei Wen , Wang Shumin
Published: April 2019

GaAs1−xBix/AlGaAs quantum wells (QWs) with varying As/Ga beam equivalent pressure (BEP) ratios were grown by solid source molecular beam epitaxy at a relatively high temperature of 350–400 °C intended for light emitting applications with wavelengths beyond 1.2 μm. Both the Bi content and the photoluminescence (PL) intensity were found to be highly dependent on As2 flux, especially for the case of growing GaAsBi at a relatively high temperature. A graded index separate confinement GaAsBi/AlGaAs single QW with 5.8% Bi exhibited a strong PL emission at 1.22 μm. The growth strategy to incorporate considerable Bi into GaAs at a relatively high temperature through meticulous control of the As/Ga BEP ratio and compensation of Bi flux is demonstrated to be effective in guaranteeing a high Bi content as well as an optimal optical performance of GaAsBi QWs.
Chaos and bifurcation behavior in a fundamental power system with electromagnetic disturbance and load disturbance
Authors: Ma Hanyuan , Min Fuhong , Huang Guan , Dou Yiping
Published: April 2019

With the increasing scale of the power grid and increasingly complex structure, the power system is always affected by various disturbances and parameter changes. The power system containing electromagnetic and load power disturbance simultaneously can exhibit rich behaviors, which accords with the reality. The chaotic oscillation caused by the power disturbance may lead to unstable operation of the power grid. Therefore, a fourth-order power system model with power disturbance is established in this paper. The nonlinear characteristic of the system under multiple disturbances is studied through the bifurcation diagram, Lyapunov exponent spectrum and the phase plane. The influence of the disturbance amplitude and frequency on the system under the condition of different frequency ratio is presented through the basin of attraction with parameter mapping, and the states of different motions of the system are given more intuitively, which is helpful for better understanding the chaotic behaviors of power system.
Semi-analytic shape function of high-harmonic electron cyclotron emission in magnetically confined plasma
Authors: Leem June-eok , Jo Jawon , Yun Gunsu S.
Published: April 2019

Semi-analytical expressions for the electron cyclotron emission (ECE) shape function are developed for arbitrary high harmonics. The integrand of the mth harmonic ECE shape function is fitted with the readily integrable test function parameterized by plasma temperature Te, harmonic number m, and emission angle θ. Semi-analytical formulae for high harmonic ECE emissivities are obtained by integrating the test integrand with the fitting parameters obtained from regression analysis. The semi-analytical expressions match with the numerically integrated ECE shape functions very well for a wide range of Te (100 eV–12 800 eV), m (2–10), and θ (10.0°–89.9°) values. The expressions can be applicable for rapid analysis of ECE spectra in magnetically confined fusion plasmas.
Kinetic network model to explain gain-of-function mutations in ERK2 enzyme
Authors: Misiura Mikita , Kolomeisky Anatoly B.
Published: April 2019

ERK2 is a kinase protein that belongs to a Ras/Raf/MEK/ERK signaling pathway, which is activated in response to a range of extracellular signals. Malfunctioning of this cascade leads to a variety of serious diseases, including cancers. This is often caused by mutations in proteins belonging to the cascade, frequently leading to abnormally high activity of the cascade even in the absence of an external signal. One such “gain-of-function” mutation in the ERK2 protein, called a “sevenmaker” mutation (D319N), was discovered in 1994 in Drosophila. The mutation leads to disruption of interactions of other proteins with the D-site of ERK2 and results, contrary to expectations, in an increase of its activity in vivo. However, no molecular mechanism to explain this effect has been presented so far. The difficulty is that this mutation should equally negatively affect interactions of ERK2 with all substrates, activators, and deactivators. In this paper, we present a semiquantitative kinetic network model that gives a possible explanation of the increased activity of mutant ERK2 species. A simplified biochemical network for ERK2, viewed as a system of coupled Michaelis-Menten processes, is presented. Its dynamic properties are calculated explicitly using the method of first-passage processes. The effect of mutation is associated with changes in the strength of interaction energy between the enzyme and the substrates. It is found that the dependence of kinetic properties of the protein on the interaction energy is nonmonotonic, suggesting that some mutations might lead to more efficient catalytic properties, despite weakening intermolecular interactions. Our theoretical predictions agree with experimental observations for the sevenmaker mutation in ERK2. It is also argued that the effect of mutations might depend on the concentrations of substrates.
Ti-fraction-induced electronic and magnetic transformations in titanium oxide films
Authors: Xu Meiling , Zhong Xin , Lv Jian , Cui Wenwen , Shi Jingming , Kanchana V. , Vaitheeswaran G. , Hao Jian , Wang Yanchao , Li Yinwei
Published: April 2019

Titanium dioxide has been widely used in modern industrial applications, especially as an effective photocatalyst. Recently, freestanding TiO2 films with a markedly reduced bandgap of ∼1.8 eV have been synthesized, indicating that the dimension has a considerable influence on the bulk band gap (>∼3 eV) and enhances the adsorption range of visible light. Titanium oxide compounds have various stoichiometries and versatile properties. Therefore, it is very necessary to explore the electronic properties and functionalities of other titanium oxide films with different stoichiometries. Here, we combined structure searches with first-principle calculations to explore candidate Ti–O films with different stoichiometries. In addition to the experimentally synthesized TiO2 film, the structure searches identified three new energetically and dynamically stable Ti–O films with stoichiometries of Ti3O5, Ti3O2, and Ti2O. Calculations show that the Ti–O films undergo several interesting electronic transformations as the Ti fraction increases, namely, from a wide-gap semiconductor (TiO2, 3.2 eV) to a narrow-gap semiconductor (Ti3O5, 1.80 eV) and then to metals (Ti3O2 and Ti2O) due to the abundance of unpaired Ti_d electrons. In addition to the electronic transformations, we observed nonmagnetic (TiO2) to ferromagnetic (Ti3O5, Ti3O2, and Ti2O) transformations. Notably, the Ti3O5 film possesses both narrow-gap semiconductive and ferromagnetic properties, with a large magnetic moment of 2.0 µB per unit cell; therefore, this film has high potential for use in applications such as spintronic devices. The results highlight metal fraction-induced electronic and magnetic transformations in transition metal oxide films and provide an alternative route for the design of new, functional thin-film materials.
Aerodynamic forces and vortical structures of a flapping wing at very low Reynolds numbers
Authors: Lyu Yu Zhu , Zhu Hao Jie , Sun Mao
Published: April 2019

Reynolds number (Re) for miniature insects is in the range of 80–10. Here, we study how the aerodynamic forces change in this Re range when the flapping mode commonly used by larger insects is employed and explore the physical reasons for the change. We find that at Re below ∼70, the lift decreases and the drag increases rapidly with decreasing Re. This can be explained as follows. In this Re range, the viscous effect becomes very large. Much of the clockwise (CW) vorticity in the leading-edge vortex is diffused to be far above the wing and moves backward relative to the wing, and some of the counterclockwise (CCW) vorticity in the boundary layer at the lower surface of the wing is diffused to be more forward, and the boundary layer becomes thicker. This results in less CW vorticity moving with the wing and less CCW vorticity moving backward of the wing, causing a reduction in the time rate of change in the vertical component of the total first moment of vorticity, i.e., the reduction in the lift. The above changes in vorticity distributions also increase the vertical distance between the CW vorticity and the CCW vorticity, causing an increase in the time rate of change in the horizontal component of the total first moment of vorticity, i.e., the increase in the drag. These results show that if miniature insects flap their wings as the larger ones do, the aerodynamic forces required for flight cannot be produced and new flapping mode must be used.
Dynamics of droplet and liquid layer penetration in three-dimensional porous media: A lattice Boltzmann study
Authors: Shi Y. , Tang G. H. , Lin H. F. , Zhao P. X. , Cheng L. H.
Published: April 2019

Liquid penetration analyses for porous media are of great importance in a wide range of industrial applications including, but not limited to, water infiltration in complex soil, hydrocarbon recovery, and liquid seepage through sediments. Depicting the details of two-phase flow in porous media is challenging due to the complex fluid-solid interaction in porous structure. In the present work, we use the three-dimensional multiphase lattice Boltzmann model with a large density ratio to investigate the droplet and liquid layer penetration in complex porous media. It is found that lower porosity leads to larger interactions at the liquid-solid interface and causes stronger drag force acting on the droplet. Both hydrophobic and hydrophilic substrates tend to facilitate droplet migration from the outside to the inside of the porous media. Decreasing the interfacial tension enhances liquid deformation and results in more liquid breakup. Due to the large total momentum dissipation, an increased viscosity ratio causes a reduction of the penetration rate. Even with identical porosity, the pores in parallel to the gravitational force, compared with the perpendicular structure, make the drag force relatively smaller, leading to a faster penetration and stretching interfaces. Overall, this work not only demonstrates the capacity of the multiphase lattice Boltzmann method but also sheds some light on the mechanism of droplet and liquid layer penetration through the porous media.
Interwell carrier transport in InGaN/(In)GaN multiple quantum wells
Authors: Marcinkevičius Saulius , Yapparov Rinat , Kuritzky Leah Y. , Wu Yuh-Renn , Nakamura Shuji , DenBaars Steven P. , Speck James S.
Published: April 2019

Uniform carrier distribution between quantum wells (QWs) of multiple QW light emitting diodes (LEDs) and laser diodes is important for the efficiency of device operation. In lasers, the uniform distribution ensures that all the QWs contribute to lasing; in LEDs, it enables high power operation with minimal Auger losses and a maximal efficiency. The carrier distribution between the QWs takes place via interwell (IW) transport. In polar GaN-based structures, the transport might be hindered by the strong carrier confinement and the internal electric fields. In this work, we study the IW transport in InGaN/(In)GaN multiple QW structures typical for ultraviolet-emitting devices with different well and barrier parameters. Experiments have been performed by means of time-resolved photoluminescence. We find that the IW transport rate is limited by the hole thermionic emission, which for InGaN/GaN QWs produces long transport times, ∼1 ns per well, and a nonuniform IW carrier distribution. However, adding 5% In to the barriers completely changes the situation with the transport time decreasing by a factor of four and the hole thermionic emission energy from 200 meV to 70 meV. This study shows that using InGaN barriers is a promising pathway toward efficient high power InGaN LEDs.
A pruned collocation-based multiconfiguration time-dependent Hartree approach using a Smolyak grid for solving the Schrödinger equation with a general potential energy surface
Authors: Wodraszka Robert , Carrington Tucker
Published: April 2019

Standard multiconfiguration time-dependent Hartree (MCTDH) calculations use a direct product basis and rely on the potential being a sum of products (SOPs). The size of the direct product MCTDH basis scales exponentially with the number of atoms. Accurate potentials may not be SOPs. We introduce an MCTDH approach that uses a pruned basis and a collocation grid. Pruning the basis significantly reduces its size. Collocation makes it possible to do calculations using a potential that is not a SOP. The collocation point set is a Smolyak grid. Strategies using pruned MCTDH bases already exist, but they work only if the potential is a SOP. Strategies for using MCTDH with collocation also exist, but they work only if the MCTDH basis is a direct product. In this paper, we combine a pruned basis with collocation. This makes it possible to mitigate the direct-product basis size problem and do calculations when the potential is not a SOP. Because collocation is used, there are no integrals and no need for quadrature. All required matrix-vector products can be evaluated sequentially. We use nested sets of collocation points and hierarchical basis functions. They permit efficient inversion of the (large) matrix whose elements are basis functions evaluated at points, which is necessary to transform values of functions at points to basis coefficients. The inversion technique could be used outside of chemical physics. We confirm the validity of this new pruned, collocation-based (PC-)MCTDH approach by calculating the first 50 vibrational eigenenergies of CH2NH.
Oriented layered Bi2O2Se nanowire arrays for ultrasensitive photodetectors
Authors: Li Jie , Wang Zhenxing , Chu Junwei , Cheng Zhongzhou , He Peng , Wang Junjun , Yin Lei , Cheng Ruiqing , Li Ningning , Wen Yao , He Jun
Published: April 2019

Due to its high carrier mobility, superior air stability, and intriguing self-modulation doping effects, Bi2O2Se has shown great potential for applications in high performance field-effect transistors and infrared photodetectors. However, Bi2O2Se generally tends to form 2D micromorphology because of its native layered structure. Here, we developed a space-confined CVD method to realize the epitaxial growth of highly oriented 1D Bi2O2Se arrays. The controllable length and width of the vertical growth nanowires mainly distribute in the ranges of 30–42 μm and 120–160 nm, respectively. The orientation of Bi2O2Se nanowires was determined by the epitaxial relationship between Bi2O2Se {110} and mica {00n} planes. In addition, various morphologies of Bi2O2Se including 1D nanowires, 2D nanosheets, and rectangular nanosheets can be controllably synthesized by precisely modifying the growth temperature. The integrated detector based on the as-synthesized Bi2O2Se nanowire arrays demonstrated excellent performances in the spectrum from the UV to near-infrared regime. The responsivity, detectivity, external quantum efficiency, and response time can reach up to 722.2 A W−1, 5.64 × 1011 Jones, 189 000%, and 0.267 ms, respectively. These findings manifest that the oriented Bi2O2Se nanowire arrays have great prospects in ultrafast and near-infrared photodetection applications.
On changes of variable that preserve convergence and absolute convergence of Fourier-Haar series
Authors: Bitsadze K. R.
Published: April 2019

It is established that among all the differentiable homeomorphic changes of variable only the functions

and

for

preserve convergence everywhere of the Fourier-Haar series. The same is true for absolute convergence everywhere.

Bibliography: 8 titles.
Turán, Fejér and Bohman extremal problems for the multivariate Fourier transform in terms of the eigenfunctions of a Sturm-Liouville problem
Authors: Gorbachev D. V. , Ivanov V. I.
Published: April 2019

The Turán, Fejér and Bohman extremal problems for the multivariate Fourier transform in terms of the eigenfunctions of a Sturm-Liouville problem on the Cartesian product of half-lines are solved under natural conditions on a weight function defined as a product of one-dimensional weight functions. Extremal functions are constructed. A multivariate Markov quadrature formula is proved based on the zeros of eigenfunctions of the Sturm-Liouville problem. This quadrature formula is shown to be sharp on entire multivariate functions of exponential type. A Paley-Wiener type theorem is proved for the multivariate Fourier transform. A weighted

-analogue of the Kotel’nikov-Nyquist-Whittaker-Shannon sampling theorem is put forward.

Bibliography: 42 titles.
Differentiability of the Minkowski

-function. III
Authors: Kan I. D.
Published: April 2019

A new result on the derivative of the Minkowski function is established.

Bibliography: 14 titles.
Smoothness of functions and Fourier coefficients
Authors: Dyachenko M. I. , Mukanov A. B. , Tikhonov S. Yu.
Published: April 2019

We consider functions represented as trigonometric series with general monotone Fourier coefficients. The main result of the paper is the equivalence of the

modulus of smoothness,

, of such functions to certain sums of their Fourier coefficients. As applications, for such functions we give a description of the norm in the Besov space and sharp direct and inverse theorems in approximation theory.

Bibliography: 34 titles.
Properties of the spectrum of an elliptic boundary value problem with a parameter and a discontinuous nonlinearity
Authors: Pavlenko V. N. , Potapov D. K.
Published: April 2019

An elliptic Dirichlet boundary value problem is studied which has a nonnegative parameter

multiplying a discontinuous nonlinearity on the right-hand side of the equation. The nonlinearity is zero for values of the phase variable not exceeding some positive number in absolute value and grows sublinearly at infinity. For homogeneous boundary conditions, it is established that the spectrum

of the nonlinear problem under consideration is closed (

consists of those parameter values for which the boundary value problem has a nonzero solution). A positive lower bound and an upper bound are obtained for the smallest value of the spectrum,

. The case when the boundary function is positive, while the nonlinearity is zero for nonnegative values of the phase variable and nonpositive for negative values, is also considered. This problem is transformed into a problem with homogeneous boundary conditions. Under the additional assumption that the nonlinearity is equal to the difference of functions that are nondecreasing in the phase variable, it is proved that

and that for each

the problem has a nontrivial semiregular solution. If there exists a positive constant

such that the sum of the nonlinearity and

is a function which is nondecreasing in the phase variable

, then for any

the boundary value problem has a minimal nontrivial solution

. The required solution is semiregular, and

is a decreasing mapping with respect to

on

. Applications of the results to the Gol’dshtik mathematical model for separated flows in an incompressible fluid are considered.

Bibliography: 37 titles.
Challenges associated with the development and transfer of assisted breeding technology in marsupials and monotremes: lessons from the koala, wombat and short-beaked echidna
Authors: Johnston Stephen
Published: April 2019

This reflective review describes how a research model, which was originally established for the successful AI of the koala (Phascolarctos cinereus), is currently being developed and extended to the wombat (Lasiorhinus latifrons and Vombatus ursinus) and short-beaked echidna (Tachyglossus aculeatus). The research model centres around the establishment of an AI program and involves: (1) semen collection, evaluation and preservation, requiring an understanding of male reproductive physiology and gamete biology; (2) timing of insemination, based on a knowledge of oestrous cycle and gestation physiology and oestrous behaviour; and (3) the appropriate placement of semen, which relies on an accurate description of female reproductive anatomy. Published and unpublished studies of assisted breeding technology (ABT) development in all three species of Australian mammals reported in this review (koala, wombat and short-beaked echidna) clearly demonstrate the importance of recognising species-specific variation in reproductive biology. Even in closely related species, such as the koala and wombat, subtle differences in reproductive physiology can hinder the transfer of ABT across species. Significant progress in marsupial and monotreme ABT will also require adequate access to captive wildlife colonies (zoos, university collections and private partners) in sufficient numbers in order to conduct quality science.
Corrigendum to: IQ motif containing D (IQCD), a new acrosomal protein involved in the acrosome reaction and fertilisation
Authors: Zhang Peng , Jiang Wanjun , Luo Na , Zhu Wenbing , Fan Liqing
Published: April 2019

The acrosome is single, large, dense-core secretory granule overlying the nucleus of most mammalian spermatozoa. Its exocytosis, the acrosome reaction, is a crucial event during fertilisation. In this study we identified a new acrosome-associated gene, namely IQ motif containing D (IQCD), expressed nearly in multiple tissues with highest expression levels in the testis. In mouse testis, Iqcd transcript accumulated from Postnatal Day (PND) 1 to adulthood. However, expression of IQCD protein at the testicular development stage started primarily from PND 18 and increased in an age-dependent manner until plateauing in adulthood. IQCD was primarily accumulated in the acrosome area of round and elongating spermatids within seminiferous tubules of the testes during the late stage of spermiogenesis; this immunolocalisation pattern is similar in mice and humans. IQCD levels in spermatozoa were significantly lower in IVF patients with total fertilisation failure or a low fertilisation rate than in healthy men. Anti-IQCD antibody significantly inhibited the acrosome reaction and slightly reduced protein tyrosine phosphorylation levels in human spermatozoa, but specifically blocked murine IVF. IQCD interacted with mammalian homolog of C. elegans uncoordinated gene 13 (Munc13) in spermatozoa and may participate in acrosome exocytosis. In conclusion, this study identified a new acrosomal protein, namely IQCD, which is involved in fertilisation and the acrosome reaction.
Science, health, and cultural literacy in a rapidly changing communications landscape
Authors: Scrimshaw Susan C.
Published: April 2019

There is a gap between how many scientists communicate and how most people understand and interpret messages. This article argues that the extensive science communications literature needs to be joined by the health literacy literature and anthropological work on cultural variations in hearing and understanding messages. Rapid changes and differences in how people in the United States get information are also discussed. Better understanding of how people get and perceive messages, and how access to information and to health services affects their behavior, should be an iterative and interdisciplinary effort. Community involvement in developing communication strategies is strongly encouraged.
K isotopes as a tracer for continental weathering and geological K cycling
Authors: Li Shilei , Li Weiqiang , Beard Brian L. , Raymo Maureen E. , Wang Xiaomin , Chen Yang , Chen Jun
Published: April 2019

Significance

The potassium stable isotope system is a powerful new geochemical tool for understanding continental weathering linked to Earth’s climate. Potassium isotopes fractionate strongly during silicate weathering, and δ
41
K values in riverine dissolved loads correlate with the silicate weathering intensity of drainage basins. We provide an estimate of the δ
41
K value for the global riverine input into the oceans and demonstrate the sensitivity of δ
41
K in seawater to the continental silicate weathering process.
Counterexamples in scale calculus
Authors: Filippenko Benjamin , Zhou Zhengyi , Wehrheim Katrin
Published: April 2019

Significance

The counterexamples presented here are the first of this kind for notions of differentiability that satisfy a chain rule. Their context arises naturally from requiring differentiability of crucial maps in the theory of pseudoholomorphic curves in symplectic geometry. This serves to illuminate some of the key reasons and major technical obstacles for the extensive recent development of analytic foundations in this field. We moreover reestablish some key calculus facts in polyfold theory under additional assumptions that are imposed by the theory and satisfied in practice. This illuminates how the obstacles are overcome and allows users of polyfold theory to make new arguments more akin to those in standard calculus using general properties rather than working from definitions.
Hypoxia-inducible factors in CD4+T cells promote metabolism, switch cytokine secretion, and T cell help in humoral immunity
Authors: Cho Sung Hoon , Raybuck Ariel L. , Blagih Julianna , Kemboi Edna , Haase Volker H. , Jones Russell G. , Boothby Mark R.
Published: April 2019

Significance

The precise regulation of antibody responses is central to the efficacy of vaccines and to our handling of microbes and infections. Antibody quality is enhanced in germinal center reactions, and this microstructure in tissue has to cope with limited oxygen. This work shows that a pair of hypoxia-inducible factor (HIF) proteins, gene regulators that respond to low oxygen but also are induced by T cell activation, must be expressed in helper T cells in order for immunization to yield a good antibody response. The evidence favors a multifactorial mechanism: HIFs shift the balance between follicular regulatory and helper T cells but also regulate metabolism, numbers of follicular helpers, and molecules they express to promote antibody production.
How a well-adapting immune system remembers
Authors: Mayer Andreas , Balasubramanian Vijay , Walczak Aleksandra M. , Mora Thierry
Published: April 2019

Significance

The adaptive immune system is able to protect us from a large variety of pathogens, even ones it has not seen yet. Can predicting the future pathogen distribution help in protection? We find that a combination of probabilistic forecasting and occasional sampling of the current environment reduces infection costs—a scheme easily implemented by the memory repertoire. The proposed theoretical framework offers a modular recipe for updating the memory repertoire, which quantitatively predicts the strength of the immune response in flu-vaccination experiments, unlike other update schemes. It also links the observed early life dynamics of the memory pool to the sparseness properties of the pathogen distribution and competitive receptor dynamics for pathogens.
Commonly used FRET fluorophores promote collapse of an otherwise disordered protein
Authors: Riback Joshua A. , Bowman Micayla A. , Zmyslowski Adam M. , Plaxco Kevin W. , Clark Patricia L. , Sosnick Tobin R.
Published: April 2019

Significance

Proteins adopt disordered ensembles prior to folding and sometimes as a part of their function. Simulations and FRET studies often described disordered conformations as more compact than the random coil states observed at high denaturant, whereas small-angle X-ray scattering (SAXS) indicates that these conformations remain expanded. Resolving this discrepancy improves our understanding of the properties of proteins, such as whether water is a sufficiently poor solvent to drive nonspecific collapse. We achieve reconciliation by showing the addition of FRET fluorophores reduces the disordered protein’s dimensions. Detailed analysis of FRET and SAXS, along with accounting for fluorophore-induced contraction, demonstrates that disordered and unfolded proteins often remain solvated and expanded without denaturant, properties that minimize misfolding and aggregation.
Structural dynamics and transient lipid binding of synaptobrevin-2 tune SNARE assembly and membrane fusion
Authors: Lakomek Nils-Alexander , Yavuz Halenur , Jahn Reinhard , Pérez-Lara Ángel
Published: April 2019

Significance

The vesicular membrane protein synaptobrevin-2 (syb-2) plays an important role in vesicular membrane fusion at the neuronal synapse by participating in the dynamic formation of the SNARE complex. Here, by a combination of solution-state NMR and fluorescence spectroscopy, we find that syb-2 in its prefusion form, before forming the SNARE complex, shows high internal flexibility, characteristic for an intrinsically disordered protein (IDP). But it also reveals an increasing rigidity from the N to C terminus that correlates with an observed increase in lipid binding affinity as well as the known increased rate for C-terminal compared with N-terminal SNARE zippering. This provides a mechanistic perspective on how an IDP and its lipid interactions can lower the energy barrier for membrane fusion.