bluuebunny/crossref_metadata_2025 huggingface dataset:
Input voltage sharing control scheme for input series and output series DC/DC converters using paralleled MOSFETs
Authors: Qu Lu , Zhang Donglai
Published: November 2017

This study proposes an input‐voltage‐sharing control scheme for use in input‐series‐output‐series (ISOS) systems. An ISOS system consists of a set of closed‐loop DC/DC converters. Each converter has a metal–oxide–semiconductor field‐effect transistor (MOSFET) connected in parallel on the input side that is controlled by an input‐voltage‐sharing loop. The MOSFET works in the linear region to adjust the input power equilibrium. The proposed control scheme makes the closed‐loop converters function as power devices that can be combined quickly and flexibly according to the specific voltage conversion requirements, which greatly shortens the time required to develop an ISOS system. The design principle of the input‐voltage‐sharing loop and the time and frequency domain simulation results are also provided in this study. A 600 W prototype composed of two DC/DC converters was built and employed to verify the steady state and dynamic characteristics of the proposed control scheme.
Effective restoration strategies of interdependent power system and communication network
Authors: Baidya Prabin M. , Sun Wei
Published: November 2017

The power system is continuously evolving towards a smarter grid by adding intelligent electrical devices that leverage communication technologies to provide visualisation, control and automation. The integration of power system and communication network has brought challenges into the resilience of interdependent networks. Following an outage or blackout, system operators cannot only restore one network while simply ignoring the interconnection with the other network. Effective restoration strategies that involve co‐ordination between power system and communication network have become critical in enhancing the resilience. An optimisation‐based restoration strategy is developed to coordinate the restoration actions between two networks. The problem is modelled as a mixed integer linear programming problem, with the objective of activating every node in both networks with the minimum number of activation/energisation of branches. The developed strategies are tested on the modified IEEE 14‐bus system incorporating communication network. Simulation results demonstrate that the coordinated restoration strategies are effective and critical in the successful recovery of interdependent networks. The developed model could also provide insights in network design and planning to enhance the resilience of interdependent power system and communication network.
Research on smart tracking strategy of wind power and energy storage combined generation system based on three‐stage rolling optimisation
Authors: Wu Linlin , Liu Hui , Bai Kai
Published: November 2017

Wind power consumption has become a bottleneck in the development of wind power. Based on the energy storage's redistribution ability of wind power in time scale, the utilisation efficiency of wind power accommodation capability can be significantly improved. However, traditional plan tracking strategy of wind power and energy storage combined system usually makes decisions based on current operating conditions. Since the strategy does not consider the future regulation requirement, the energy storage system may be out of operation since the state of charge (SOC) is too high or too low. Aiming at the shortage of current tracking strategy, this paper proposes a smart tracking strategy of wind power and energy storage combined generation system based on three‐stage rolling optimisation, including day‐ahead, within‐day, and real time. The reserved capacity of energy storage station is determined according to the wind power ramping trend prediction method in day‐head stage. The low limit of energy storage station SOC is corrected according to ultra‐short time wind power prediction in within‐day stage. In real‐time stage, the energy storage system selectively participates in active power control of combined system according to the actual power deviation and SOC operating range. Simulation result shows that the proposed method can effectively improve the combined system generating capacity.
Analytical and numerical studies of positive ion beam expansion for surface treatment applications
Authors: Lounes-Mahloul Soumya , Bendib Abderrezeg , Oudini Noureddine
Published: November 2017

The aim of this work is to study the expansion in vacuum, of a positive ion beam with the use of one dimensional (1D) analytic model and a two dimensional Particle-In-Cell (2D-PIC) simulation. The ion beam is extracted and accelerated from preformed plasma by an extraction system composed of two polarized parallel perforated grids. The results obtained with both approaches reveal the presence of a potential barrier downstream the extraction system which tends to reflect the ion flux. The dependence of the critical distance for which all extracted ions are reflected, is investigated as a function of the extracted ion beam current density. In particular, it is shown that the 1D model recovers the well-known Child-Langmuir law and that the 2D simulation presents a significant discrepancy with respect to the 1D prediction. Indeed, for a given value of current density, the transverse effects lead to a greater critical distance.
Experimental study of light emitted by spark-generated bubbles in water
Authors: Vokurka Karel , Buogo Silvano
Published: November 2017

The emission of light from spark-generated bubbles freely oscillating in water far from boundaries is studied experimentally. The observations concentrate on light flashes radiated at final stages of the first bubble contraction and early stages of the following bubble expansion. It is shown that the shape of the emitted light pulses is not “Gaussian”, but asymmetric with a leading edge moderately growing and a trailing edge steeply decreasing. The maximum values and widths of these optical pulses are determined for bubbles having different sizes and oscillating with different intensities. The variation of the maximum values and pulse widths with bubble size and intensity of oscillation is discussed, as well as the observed weak correlation between these two quantities.
Chemoselective Synthesis of N-Arylenaminones and 3-Aroylquinolines by Synergistic Control of Temperature and Amount of Catalyst
Authors: Yu Fuchao , Zhou Pan , Hu Biao , Rao Kairui , Li Lingdan , Yang Jiao , Gao Chuanzhu , Wang Fengping
Published: November 2017

An efficient and practical method has been developed for the divergent synthesis of N-arylenaminones and 3-aroylquinolines from 2-aminoaryl ketones and N,N-dimethylenaminones in the presence of 4-toluenesulfonic acid through synergistic control of the temperature and amount of catalyst. Furthermore, gram-scale synthesis and synthetic applications have been evaluated. Features of this protocol include controllable results, mild conditions, good functional-group tolerance, operational simplicity, and excellent yields.
Recent Advances in the Catalytic Asymmetric Construction of Phosphorus-Substituted Quaternary Carbon Stereocenters
Authors: Chen Long
Published: November 2017

Phosphorus-substituted quaternary carbon stereocenters exist widely in drugs and biologically active compounds. Catalytic asymmetric synthesis of such quaternary carbon stereogenic centers is of significant importance, with four synthetic strategies being established. This review summarizes the recent progress in this field, including the advantages and limitations of each strategy, briefly discusses the reaction mechanisms and challenges, and outlines synthetic opportunities still open.

1 Introduction

2 Asymmetric Hydrophosphonylation

3 Asymmetric Electrophilic Phosphination

4 Asymmetric Functionalization of P-Substituted Methine Compounds

5 Asymmetric Addition to α-Keto- or α-Ketiminophosphonates

6 Conclusion
Recent Progress in Catalytic Enantioselective Desymmetrization of Prochiral Organosilanes for the Synthesis of Silicon-Stereogenic Compounds
Authors: Shintani Ryo
Published: November 2017

It is highly important to develop efficient synthetic methods for various enantioenriched chiral compounds due to their high significance in our life. In this regard, asymmetric catalysis is one of the most attractive ways of synthesizing such compounds from achiral precursors. Although various methods have been developed for the enantio­selective preparation of carbon-stereogenic compounds, the corresponding methods for silicon-stereogenic compounds are much less established. In particular, little progress has been made on catalytic enantioselective synthesis using prochiral organosilanes until recently. This account focuses on the recent progress in the catalytic enantio­selective preparation of silicon-stereogenic organosilanes through ­desymmetrization of prochiral organosilanes.

1 Introduction

2 Desymmetrization of Diorganodihydrosilanes

3 Desymmetrization of Tetraorganosilanes

3.1 Desymmetrization through Cleavage of Silicon–Carbon Bonds

3.2 Desymmetrization without Cleavage of Silicon–Carbon Bonds

4 Conclusion
Mandibular Inferior Cortex Erosion on Dental Panoramic Radiograph as a Sign of Low Bone Mineral Density in Postmenopausal Women
Authors: Carmo Juliana Zigart Brum , Medeiros Sebastião Freitas de
Published: November 2017

Objective To examine the role of the panoramic mandibular radiograph in the diagnosis of low bone mineral density (BMD) in postmenopausal women.

Methods A cross-sectional study including volunteer women aged over 40 years in amenorrhea due to ovarian failure for at least 12 months, who were cared for at the climacteric outpatient clinic of a university hospital in the city of Cuiabá, in the state of Mato Grosso, Brazil. The panoramic radiographs were evaluated using a specific software. Two aspects were analyzed in the mandibular panoramic radiograph: a qualitative aspect regarding the shape of the mandibular cortical bone, and a quantitative aspect regarding the width of the mandibular cortical bone. The morphology of the mandibular cortical bone in the digital panoramic radiograph was determined bilaterally by the observation of the bone structure between the mental foramen and the base of the jaw. The mandibular cortical bone was categorized into three groups. The mental index (MI) was used to evaluate the thickness of the mandibular cortical bone through a perpendicular line drawn from the base of the mandible at the height of the center of the mental foramen, with another line drawn tangent to the inferior border of the mandible, and a third line parallel to the line at the superior border of the mandible. The MI data are expressed in millimeters, with a normal value of 3.0 mm. The densities of the lumbar spine and femur, expressed in g/cm2, were categorized as normal, osteopenia or osteoporosis.

Results The agreement index between the MI and the BMD of the lumbar spine was good (Kappa = 0.718), but the same index between the MI and the BMD of the femoral neck was poor (Kappa = 0.443). An excellent agreement occurred when the mandibular cortical index (MCI) was compared with the BMD of the lumbar spine (Kappa = 0.912). The agreement between MCI and the BMD in the femur was moderated (Kappa = 0.579).

Conclusion The radiomorphometric indices evaluated in the mandibular panoramic radiograph are capable of identifying postmenopausal women with low mineral density in the mandible, and the results can be used to refer these women to appropriate medical investigation and/or treatment.
Rethinking Pyogenic Flexor Tenosynovitis: Biofilm Formation Treated in a Cadaveric Model
Authors: Ketonis Constantinos , Hickock Noreen , Ilyas Asif
Published: November 2017

Introduction Pyogenic flexor tenosynovitis (PFT) of the hand remains a challenging problem that often requires surgical irrigation and parenteral or oral antibiotics. The authors hypothesize that the pathophysiology and microenvironment of PFT can be likened to that of periprosthetic joint infections (PJIs), in which bacteria thrive in a closed synovial space with limited blood supply. As such, they postulate that PFT is also facilitated by bacterial attachment and biofilm formation rendering standard treatments less effective. In this study, they evaluate infected tendons for the presence of biofilm and explore new treatment strategies.

Methods Fresh human cadaveric hand tendons were harvested and divided into 0.5-cm segments. Samples were sterilized and inoculated with 1 × 104 CFU/mL green fluorescent Staphylococcus aureus (GFP-SA) for 48 hours at 37°C. After saline washing to remove plank tonic bacteria, samples were treated for 24 hours with (1) saline irrigation, (2) antibiotics (vancomycin), (3) corticosteroids, or (4) antibiotics/corticosteroid combined. Samples were visualized using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM).

Results Following bacterial challenge, CLSM revealed heterogeneous green fluorescence representing bacterial attachment with dense biofilm formation. SEM at > 3,000X, also demonstrated bacterial colonization in grape-like clusters consisted with a thick matrix characteristic of biofilm. Bacterial load by direct colony counting decreased by 18.5% with saline irrigation alone, 42.6% with steroids, 54.4% with antibiotics, and 77.3% with antibiotics/steroids combined (p < 0.05).

Conclusion Staphylococcus aureus readily formed thick biofilm on human cadaveric tendons. The addition of both local antibiotics and corticosteroids resulted in greater decreases in biofilm formation on flexor tendons than the traditional treatment of saline irrigation alone. We suggest rethinking the current treatment of PFT and recommend considering a strategy more analogous to PJI management with the adjunctive use of local antibiotics, corticosteroids, and mechanical agitation.
Veränderungen von Kohärenzgefühl, Symptombelastung und Lebens- sowie Studienzufriedenheit im Verlauf psychosozialer Beratungen
Authors: Koutsoukou-Argyraki Asimina , Bertolino Alina , Kreß Volker , Hofmann Frank-Hagen , Sperth Michael , Holm-Hadulla Rainer
Published: November 2017

Das Kohärenzgefühl spielt im Salutogenesekonzept von Aaron Antonovsky eine wichtige Rolle bei der Aufrechterhaltung bzw. der Wiederherstellung von Gesundheit. Empirische Untersuchungen belegen signifikante Zusammenhänge zwischen dem Kohärenzgefühl und verschiedenen Indikatoren psychischer Gesundheit. In der vorliegenden Studie wurde die Wirksamkeit eines integrativen Beratungskonzepts zur Förderung des Kohärenzgefühls, Reduzierung der psychischen Beeinträchtigung sowie Verbesserung der Lebens- und Studienzufriedenheit bei 153 studentischen Klienten untersucht. Korrelationen zwischen Kohärenzgefühl, psychischer Beeinträchtigung und Lebens-und Studienzufriedenheit weisen darauf hin, dass das Kohärenzgefühl eng mit der psychischen Gesundheit sowie mit der Lebens- und Studienzufriedenheit zusammenhängt. Durch psychosoziale Beratung konnten signifikante Prä-Post-Veränderungen mit mittleren bis hohen Effektstärken erreicht werden. Diese Befunde ermöglichen Folgerungen zur Modifizierbarkeit des Kohärenzgefühls und der damit einhergehenden Auswirkung auf die psychische Gesundheit und liefern Hinweise für die Wirksamkeit des integrativen ABCDE-Modells. Zusammenhänge zwischen Einschätzungen der einzelnen Dimensionen des Modells und den Prä-Post-Veränderungen werden diskutiert.

Das Kohärenzgefühl spielt im Salutogenesekonzept von Aaron Antonovsky eine wichtige Rolle bei der Aufrechterhaltung bzw. der Wiederherstellung von Gesundheit. Empirische Untersuchungen belegen signifikante Zusammenhänge zwischen dem Kohärenzgefühl und verschiedenen Indikatoren psychischer Gesundheit. In der vorliegenden Studie wurde die Wirksamkeit eines integrativen Beratungskonzepts zur Förderung des Kohärenzgefühls, Reduzierung der psychischen Beeinträchtigung sowie Verbesserung der Lebens- und Studienzufriedenheit bei 153 studentischen Klienten untersucht. Korrelationen zwischen Kohärenzgefühl, psychischer Beeinträchtigung und Lebens-und Studienzufriedenheit weisen darauf hin, dass das Kohärenzgefühl eng mit der psychischen Gesundheit sowie mit der Lebens- und Studienzufriedenheit zusammenhängt. Durch psychosoziale Beratung konnten signifikante Prä-Post-Veränderungen mit mittleren bis hohen Effektstärken erreicht werden. Diese Befunde ermöglichen Folgerungen zur Modifizierbarkeit des Kohärenzgefühls und der damit einhergehenden Auswirkung auf die psychische Gesundheit und liefern Hinweise für die Wirksamkeit des integrativen ABCDE-Modells. Zusammenhänge zwischen Einschätzungen der einzelnen Dimensionen des Modells und den Prä-Post-Veränderungen werden diskutiert.
Internetabhängigkeit, Suizidalität und selbstverletzendes Verhalten – Ein systematisches Review
Authors: Steinbüchel Toni , Herpertz Stephan , Külpmann Ina , Kehyayan Aram , Dieris-Hirche Jan , te Wildt Bert
Published: November 2017

Hintergrund Internetabhängigkeit (IA) geht mit einem hohen Maß an komorbiden psychischen Störungen, insbesondere Depressionen, Angststörungen, ADHS und Persönlichkeitsstörungen und einem erheblichen Leidensdruck einher. Im Hinblick auf das hieraus resultierende Gefahrenpotenzial untersucht die vorliegende Arbeit die aktuelle Forschungsliteratur bezüglich Suizidalität und nicht suizidalem selbstverletzendem Verhalten (NSSV) bei IA.

Methoden In einer systematischen Literaturrecherche wurden klinische und nicht-klinische Studien in 14 Datenbanken auf der Titel- Abstract-Ebene nach den häufigsten Schlagworten für IA, NSSV und Suizidalität durchsucht. Die nach Abzug der mehrfach vorhandenen Publikationen verbliebenen 2334 Artikel wurden nach definierten Ein- und Ausschlusskriterien gefiltert. Insgesamt konnten 15 Studien, die IA, NSSV und Suizidalität mittels validierter psychometrischer Instrumente erheben, in das Review eingeschlossen werden.

Ergebnisse Der Zusammenhang zwischen IA und Suizidalität wurde in 10 Studien untersucht, 4 Studien untersuchten den Zusammenhang von IA, Suizidalität und NSSV, eine Studie ausschließlich den Zusammenhang von IA und NSSV. Sämtliche Studien zeigten höhere Prävalenzen für NSSV beziehungsweise Suizidalität der Probanden mit einer IA im Vergleich zu Probanden ohne IA, wobei die Punkt-Prävalenzraten für Suizidalität mit 1,6–18,7% erheblich variierten.

Diskussion Die Ergebnisse der eingeschlossenen Publikationen legen nahe, dass Internetabhängigkeit mit einer erhöhten Rate an nicht-suizidalem selbstverletzendem Verhalten und mit einer erhöhten Suizidalität einhergeht, wobei sich für Suizidgedanken ein deutlicherer Zusammenhang abbildet als für tatsächliche suizidale Handlungen. Um ein besseres Verständnis insbesondere kausaler Zusammenhänge zwischen IA, NSSV und Suizidalität zu entwickeln, bedarf es weiterer, möglichst longitudinaler Studien.

Fazit für die Praxis  Vor dem Hintergrund der aktuellen Studienlage ist es ratsam, bei Internetabhängigen routinemäßig auch eine differenzierte Anamnese bezüglich NSSV sowie suizidalen Gedanken und Impulsen durchzuführen.
Endoscopic subtypes of colorectal laterally spreading tumors (LSTs) and the risk of submucosal invasion: a meta-analysis
Authors: Bogie Roel , Veldman Manon , Snijders Luc , Winkens Bjorn , Kaltenbach Tonya , Masclee Ad , Matsuda Takahisa , Rondagh Eveline , Soetikno Roy , Tanaka Shinji , Chiu Han-Mo , Sanduleanu-Dascalescu Silvia
Published: November 2017

Background and study aims Many studies have reported on laterally spreading tumors (LSTs), but systematic reviews of the data to determine their risk of containing submucosal invasion (SMI) are lacking. We systematically screened and analyzed the available literature to provide a more solid basis for evidence-based treatment.

Methods We conducted a systematic search in PubMed, Embase, the Cochrane Library, and Scopus for published articles until July 2017. We estimated pooled prevalence or odds ratios (ORs) with 95 % confidence intervals (CIs), using random-effects models. We classified endoscopic subtypes into granular LST, which comprises the homogeneous and nodular mixed subtypes, and non-granular LST, which comprises the flat elevated and pseudodepressed subtypes.

Results We identified 2949 studies, of which 48 were included. Overall, 8.5 % (95 %CI 6.5 % – 10.5 %) of LSTs contained SMI. The risk of SMI differed among the LST subtypes: 31.6 % in non-granular pseudodepressed LSTs (95 %CI 19.8 % – 43.4 %), 10.5 % in granular nodular mixed LSTs (95 %CI 5.9 % – 15.1 %), 4.9 % in non-granular flat elevated LSTs (95 %CI 2.1 % – 7.8 %), and 0.5 % in granular homogenous LSTs (95 %CI 0.1 % – 1.0 %). SMI was more common in distally rather than in proximally located LSTs (OR 2.50, 95 %CI 1.24 – 5.02). The proportion of SMI increased with lesion size (10 – 19 mm, 4.6 %; 20 – 29 mm, 9.2 %; ≥ 30 mm, 16.5 %). The pooled prevalence of patients with one or more LSTs in the general colonoscopy population was 0.8 % (95 %CI 0.6 % – 1.1 %).

Conclusion The majority of LSTs are non-invasive at the time of colonoscopic detection and can be treated with (piecemeal) endoscopic mucosal resection. Pretreatment diagnosis of endoscopic subtype, specifying areas of concern (nodule or depression), determines those LSTs at highest risk of containing SMI, where en bloc resection is the preferred therapy.
Leptin and its Relation to Autonomic Activity, Endothelial Cell Activation and Blood Pressure in a Young Black and White Population: The African-PREDICT study
Authors: Ahiante Blessing , Smith Wayne , Lammertyn Leandi , Schutte Aletta
Published: November 2017

An increasing prevalence of obesity-related hypertension is observed in the youth and may have severe consequences for future cardiovascular disease development. Previous studies portrayed leptin as a potential factor involved in obesity-related hypertension development. In order to understand leptin’s contributions to early cardiovascular deterioration, we investigated leptin and its associations with measures of autonomic activity, endothelial activation, and blood pressure in young healthy black and white men and women. We included 820 participants (aged 20–30 years) and determined serum leptin and endothelial cellular adhesion molecules. We measured 24-h blood pressure, heart rate, and heart rate variability components. In multivariate-adjusted regression analyses, we found consistent associations between markers of autonomic activity (such as 24-h heart rate, day and night-time heart rate as well as heart rate variability total power) and leptin in both white (all p≤0.001) and black men (all p≤0.040). These findings were absent or less prominent in women, despite their almost 10-fold higher leptin levels than men. Only in white men, 24-h diastolic blood pressure was associated with leptin (Std β=0.37; p=0.006). This association was found to be partly mediated by autonomic activity (24-h heart rate variability total power). No independent associations were observed between leptin and markers of endothelial cell activation, irrespective of race or gender. Leptin’s independent association with autonomic neural activity in a young apparently healthy population suggests an early influence of leptin on autonomic function and future blood pressure elevation especially in men.
16.13.5 Quinazolines (Update 2015)
Authors: Kang F.-A. , Yang S.-M.
Published: November 2017

This chapter is an update to the earlier Science of Synthesis contribution (Section 16.13) describing methods for the synthesis of quinazolines. It summarizes new technologies and surveys the literature published in the period 2002–2012.
30.5.6 Selenium- and Tellurium-Containing Acetals (Update 2016)
Authors: Yoshimatsu M.
Published: November 2017

This chapter is an update to the earlier Science of Synthesis contribution (Section 30.5) concerning the synthesis and reactions of selenium- and tellurium-containing acetals. Recent interest has changed to the new field of Se,N- and Te,N-acetals including 4′-selenonucleosides, which may be used as unique building blocks for new DNA and RNA analogues. The published methods for Se,N- and Te,N-acetals could open up new applications in this field.
31.5.1.2.7 Synthesis of Phenols and Phenolates by Elimination (Update 2018)
Authors: González-Bello C.
Published: November 2017

This chapter is an update to the earlier Science of Synthesis review (Section 31.5.1.2), published in 2007, describing the synthesis of monohydric phenols by elimination approaches. It focuses on recent, palladium-catalyzed arylation/aromatization methods as well as the nickel-catalyzed hydrogenolysis of diaryl ethers.
33.5.8.2 2,3-Dihydro-1H-phospholes and Derivatives (Update 2015)
Authors: Keglevich Gy. , Grün A.
Published: November 2017

This chapter is an update to the earlier Science of Synthesis contribution (Section 33.5.8) describing methods for the synthesis of 2,3-dihydro-1H-phospholes. It focuses on the literature published in the period 2004–2015.
33.5.9.2 1,2,3,4-Tetrahydrophosphinines and Derivatives (Update 2015)
Authors: Keglevich Gy. , Grün A.
Published: November 2017

This chapter is an update to the earlier Science of Synthesis contribution (Section 33.5.9) describing methods for the synthesis of 1,2,3,4-tetrahydrophosphinines. It focuses on the literature published in the period 2004–2015.
35.3.1.2.7 Synthesis by Substitution of Metals (Update 2015)
Authors: Elliott M. C. , Saleh B. A.
Published: November 2017

This chapter is an update to the earlier Science of Synthesis contribution (Section 35.3.1.2) describing methods for the synthesis of alkyl iodides from organometallic reagents, generally by addition of iodine, although other iodide sources have been used. It focuses on the literature published in the period 2005–2014.
35.3.1.4.6 Synthesis by Substitution of Other Halogens (Update 2015)
Authors: Singh F. V. , Wirth T.
Published: November 2017

Iodoalkanes are versatile reagents and precursors in a variety of organic reactions such as nucleophilic substitution, elimination, and metal-catalyzed C—C bond-forming reactions. In this chapter, various halogen-exchange approaches for the synthesis of iodoalkanes from other haloalkanes are described. The methods described cover the literature published in the period 2007–2014.
2.3.2 Organocatalyzed Addition to Activated C=C Bonds
Authors: Renzi P. , Moliterno M. , Salvio R. , Bella M.
Published: November 2017

In this chapter, several examples of organocatalyzed additions to C=C bonds carried out through a domino approach are reviewed, from the early examples to recent applications of these strategies in industry.
2.3.4 Additions to C=N Bonds and Nitriles
Authors: Kroon E. , Zarganes Tzitzikas T. , Neochoritis C. G. , Dömling A.
Published: November 2017

This chapter describes additions to imines and nitriles and their post-modifications within the context of domino reactions and multicomponent reaction chemistry.
2.10 Ring-Closing Metathesis
Authors: Lee D. , Sabbasani V. R.
Published: November 2017

Ring-closing metathesis (RCM) has emerged as a powerful synthetic tool. Depending on the unsaturated functional groups involved, ring-closing-metathesis reactions are classified into three categories: diene ring-closing metathesis, enyne ring-closing metathesis, and diyne ring-closing metathesis. These are mediated/catalyzed by metal alkylidenes or alkylidynes to form cyclic alkenes or alkynes, with ring sizes ranging from small to large, and including both carbocycles and heterocycles. Mechanistically, diene and diyne ring-closing metathesis involves an exchange reaction between the participating alkenes or alkynes, whereas enyne ring-closing metathesis involves a formal addition reaction between an alkene and an alkyne. This chapter summarizes the distinctive features of these different ring-closing metathesis processes in terms of the advancement of mechanistic understanding and the development of effective catalyst systems and their application to natural product synthesis.
Longitudinal perspectives of faculty and students on benefits and barriers to transdisciplinary graduate education: program assessment and institutional recommendations
Authors: Keck Anna-Sigrid , Sloane Stephanie , Liechty Janet M. , Paceley Megan S. , Donovan Sharon M. , Bost Kelly K. , McBride Brent A. , Fiese Barbara H.
Published: November 2017

Addressing complex societal problems, such as childhood obesity, requires transdisciplinary (TD) approaches to reach effective solutions. However, TD doctoral training programs in academic settings are still relatively new, and little is known about the benefits and barriers of participation. This study sought to longitudinally assess benefits and barriers of a TD approach to doctoral education from the perspectives of students working towards a joint PhD/MPH degree and their faculty advisors. Results show that benefits across 5-years included greater collaboration and networking, enhanced guidance and support, broadened ways of thinking, and expanded opportunities. Barriers included time demands, complicated logistics, and tension between depth versus breadth of knowledge. Similarities and differences among students and faculty are discussed. Findings provide resources for both faculty and students considering involvement with TD doctoral education, as well as for institutions and academic programs seeking to promote TD training and team science.
Advection within side-by-side liquid micro-cylinders in a cross-flow
Authors: Dong Qingming , Sau Amalendu
Published: November 2017

The gaseous SO2 entrainment from outer air stream and dispersion in binary and ternary liquid micro-cylinders appearing side-by-side are examined hereby. The separation/attachment regulated non-uniform interfacial momentum exchange creates main stream driven “primary” and shear reversed “secondary” vortices in the liquid cylinders. At separation points, the sense of rotation of the generated “primary-secondary” vortex pair remains inward directed. We define such a vortex pair as the “inflow” type. However, at stagnation or attachment points, the sense of rotation of a “primary–primary” or “secondary–secondary” vortex pair remains outward directed, and such a vortex pair is defined as the “outflow” type. For the coupled water cylinders facing an oncoming stream contaminated by gaseous SO2, its absorption and internal transport are effectively controlled by dominant “inflow” and “outflow” natured dynamics of the said vortex pairs, besides by diffusion. The evolving “inflow” natured “primary–secondary” vortex pairs at separation points actively entrain the outer SO2, whereas the “outflow” natured vortex-pairs oppose SO2 entry through the stagnation regions. Moreover, the blockage induced steady-symmetric, steady-deflected, and flip-flopping air-jets through gaps, for varied gap-ratio (1 ≤ G/R ≤ 4) and Reynolds number (30 ≤ Re ≤ 160), create distinctive impact both on quantitative SO2 absorption (mso2′) and convective nature of the SO2 transport in upper, lower, and middle cylinders, by virtue of modified strength and size of the inflow and outflow paired vortices. The present study shows that the tiny “secondary vortices” play important roles in SO2 entrainment and in effectively controlling the local absorption rate Rso2. The sudden acceleration and upward/downward deflection of gap-flows enhanced near-neck advective SO2 entrainment by suitably strengthening the “inflow” natured local vortex dynamics. Conversely, for the reduced size of secondary vortices, the saturation becomes delayed. In addition, for decreased vertical spacing of micro-cylinders (R = 40 μm) falling below the diameter-length “2R,” the SO2 absorption (mso2′) only gets slower. We provide extensive analysis of two-phase transport phenomena in terms of interactive shear-stress, pressure, and characteristic time-ratio “Tr” of advection-diffusion processes, for varied G/R, Re, and liquid phase Peclet number “Pel” (96 ≤ Pel ≤ 1333), to present a better insight into the governing physics.
Impurity-induced modulation of terahertz waves in optically excited GaAs
Authors: Kurdyubov A. S. , Trifonov A. V. , Gerlovin I. Ya. , Ignatiev I. V. , Kavokin A. V.
Published: November 2017

The effect of the photoinduced absorption of terahertz (THz) radiation in a semi-insulating GaAs crystal is studied by pulsed THz transmission spectroscopy. We found that a broad-band modulation of THz radiation may be induced by a low-power optical excitation in the spectral range of the impurity absorption band in GaAs. The measured modulation factor achieves 80%. The amplitude and frequency characteristics of the resulting THz modulator are critically dependent on the carrier density and relaxation dynamics in the conduction band of GaAs. In semi-insulating GaAs crystals, the carrier density created by the impurity excitation is controlled by the rate of their relaxation to the impurity centers. The relaxation rate and, consequently, the frequency characteristics of the modulator can be optimized by an appropriate choice of the impurities and their concentrations. The modulation parameters can be also controlled by the crystal temperature and by the power and photon energy of the optical excitation. These experiments pave the way to the low-power fast optically-controlled THz modulation, imaging, and beam steering.
Two-dimensional strain-mapping by electron backscatter diffraction and confocal Raman spectroscopy
Authors: Gayle Andrew J. , Friedman Lawrence H. , Beams Ryan , Bush Brian G. , Gerbig Yvonne B. , Michaels Chris A. , Vaudin Mark D. , Cook Robert F.
Published: November 2017

The strain field surrounding a spherical indentation in silicon is mapped in two dimensions (2-D) using electron backscatter diffraction (EBSD) cross-correlation and confocal Raman spectroscopy techniques. The 200 mN indentation created a 4 μm diameter residual contact impression in the silicon (001) surface. Maps about 50 μm × 50 μm area with 128 pixels × 128 pixels were generated in several hours, extending, by comparison, assessment of the accuracy of both techniques to mapping multiaxial strain states in 2-D. EBSD measurements showed a residual strain field dominated by in-surface normal and shear strains, with alternating tensile and compressive lobes extending about three to four indentation diameters from the contact and exhibiting two-fold symmetry. Raman measurements showed a residual Raman shift field, dominated by positive shifts, also extending about three to four indentation diameters from the contact but exhibiting four-fold symmetry. The 2-D EBSD results, in combination with a mechanical-spectroscopic analysis, were used to successfully predict the 2-D Raman shift map in scale, symmetry, and shift magnitude. Both techniques should be useful in enhancing the reliability of microelectromechanical systems (MEMS) through identification of the 2-D strain fields in MEMS devices.
A note on the accuracy of KS-DFT densities
Authors: Ranasinghe Duminda S. , Perera Ajith , Bartlett Rodney J.
Published: November 2017

The accuracy of the density of wave function methods and Kohn-Sham (KS) density functionals is studied using moments of the density, ⟨rn⟩=∫ ρ rrndτ=∫0∞4πr2ρ(r)rndr,where n=−1,−2,0,1,2,and 3 provides information about the short- and long-range behavior of the density. Coupled cluster (CC) singles, doubles, and perturbative triples (CCSD(T)) is considered as the reference density. Three test sets are considered: boron through neon neutral atoms, two and four electron cations, and 3d transition metals. The total density and valence only density are distinguished by dropping appropriate core orbitals. Among density functionals tested, CAMQTP00 and ωB97x show the least deviation for boron through neon neutral atoms. They also show accurate eigenvalues for the HOMO indicating that they should have a more correct long-range behavior for the density. For transition metals, some density functional approximations outperform some wave function methods, suggesting that the KS determinant could be a better starting point for some kinds of correlated calculations. By using generalized many-body perturbation theory (MBPT), the convergence of second-, third-, and fourth-order KS-MBPT for the density is addressed as it converges to the infinite-order coupled cluster result. For the transition metal test set, the deviations in the KS density functional theory methods depend on the amount of exact exchange the functional uses. Functionals with exact exchange close to 25% show smaller deviations from the CCSD(T) density.
Understanding diffusion of intrinsically disordered proteins in polymer solutions: A disorder plus collapse model
Authors: Wang Juan , Bian Yukun , Cao Xiuli , Zhao Nanrong
Published: November 2017

Understanding diffusion of intrinsically disordered proteins (IDPs) under crowded environments is of ubiquitous importance to modelling related dynamics in biological systems. In the present work, we proposed a theoretical framework to study the diffusion behavior of IDPs in polymer solutions. IDP is modeled as an ensemble of particles with a wide range of gyration radius subject to Flory-Fisk distribution, where the collapse effect which leads to the shrink of IDP due to polymer crowding is included. The diffusion coefficient of IDP is calculated as the average, denoted by 〈D〉, over the values of the particle samples. By properly incorporating the scaling relations for diffusion coefficient of nanoparticle (NP) in polymer solutions, we are able to evaluate 〈D〉 straightforwardly and reveal the disorder and collapse effects on IDP’s diffusion in an explicit manner. Particular attentions are paid on comparison between the diffusion coefficient of an IDP and that of a NP. Results demonstrate that both disorder and collapse can enhance IDP diffusion rate. Our analysis shows that the crossover behavior reported by experiments can be actually a general phenomenon, namely, while a NP with smaller size than that of an IDP diffuses faster in simple solutions, the IDP may become the faster one under crowded conditions. We apply our theory to analyze the diffusion of several types of IDP in a few different polymer solutions. Good agreements between the theoretical results and the experimental data are obtained.
Dense arrays of site-controlled quantum dots with tailored emission wavelength: Growth mechanisms and optical properties
Authors: Surrente Alessandro , Felici Marco , Gallo Pascal , Rudra Alok , Dwir Benjamin , Kapon Eli
Published: November 2017

We demonstrate the fabrication of arrayed, site-controlled pyramidal InGaAs/GaAs quantum dots (QDs) grown by metalorganic vapor phase epitaxy with tailored emission energy and periods as small as 200 nm, suitable for the integration with compact photonic structures. The observed variation of the QD emission energy with the geometric parameters of the array is attributed to adatom and precursor diffusion mechanisms during epitaxial growth. By adjusting the pattern geometry, the emission energy can be tuned over a wide range of ∼80 meV around 1.4 eV, with inhomogeneous broadening <10 meV. Single photon emission of isolated QDs with gX,X(2)(0)=0.11 is demonstrated, which attests to the suitability of these QDs for nanophotonic applications.
Three dimensional reductions of four-dimensional quasilinear systems
Authors: Pavlov Maxim V. , Stoilov Nikola M.
Published: November 2017

In this paper, we show that four-dimensional quasilinear systems of first order integrable by the method of two-dimensional hydrodynamic reductions possess infinitely many three-dimensional hydrodynamic reductions, which are also integrable systems. These three-dimensional multi-component integrable systems are irreducible to two-dimensional hydrodynamic reductions in a generic case.
Terahertz birefringence and absorption of a chalcopyrite CdSiP2 crystal
Authors: Carnio B. N. , Zawilski K. T. , Schunemann P. G. , Elezzabi A. Y.
Published: November 2017

The terahertz (THz) birefringence and absorption of a chalcopyrite CdSiP2 (CSP) crystal are studied at frequencies between 0.5 and 2.9 THz. Time-domain spectroscopy measurements are used to record the phonon-polariton dispersion and reststrahlen band absorption (centered at 2.03 THz) of CSP's lowest-frequency E mode. The ordinary and extraordinary refractive indices of this material, along with the extinction coefficients, are determined over the investigated frequency range. The uniform CSP birefringence (∼0.08) and the low extinction coefficient values (≤0.008) at frequencies between 0.5 and 1.9 THz suggest the potential for waveplate applications.
New type of chimera and mutual synchronization of spatiotemporal structures in two coupled ensembles of nonlocally interacting chaotic maps
Authors: Bukh Andrei , Rybalova Elena , Semenova Nadezhda , Strelkova Galina , Anishchenko Vadim
Published: November 2017

We study numerically the dynamics of a network made of two coupled one-dimensional ensembles of discrete-time systems. The first ensemble is represented by a ring of nonlocally coupled Henon maps and the second one by a ring of nonlocally coupled Lozi maps. We find that the network of coupled ensembles can realize all the spatio-temporal structures which are observed both in the Henon map ensemble and in the Lozi map ensemble while uncoupled. Moreover, we reveal a new type of spatiotemporal structure, a solitary state chimera, in the considered network. We also establish and describe the effect of mutual synchronization of various complex spatiotemporal patterns in the system of two coupled ensembles of Henon and Lozi maps.
Delayed thermal depolarization of Bi0.5Na0.5TiO3-BaTiO3 by doping acceptor Zn2+ with large ionic polarizability
Authors: Li Ling , Zhu Mankang , Zhou Kailing , Wei Qiumei , Zheng Mupeng , Hou Yudong
Published: November 2017

In this paper, (Bi0.5Na0.5)0.94Ba0.06Ti1-xZnxO3 ceramics (0 ≤ x ≤ 0.06) were prepared by the solid oxide reaction route. The doping of Zn2+ into Bi0.5Na0.5TiO3-6BaTiO3 delays the crossover from nonergodic to ergodic states, and the thermal depolarization temperature Td is delayed from 85 °C for pure samples to 120 °C for samples doped by 6% Zn2+, as confirmed by temperature-dependent dielectric and ferroelectric measurements. It suggests that the variation of the Td could be ascribed to the reformation of the long-range ferroelectric order due to the large ionic polarizability of Zn2+. The high ionic polarizability of Zn2+ can result in a large dipole moment of BO6 octahedra, thus strengthening the coherence of neighboring dipoles and suppressing the ferroelectric–relaxor transition. These results improve our understanding on the thermal depolarization of Bi0.5Na0.5TiO3-based ferroelectrics.
WhiB6 regulation of ESX-1 gene expression is controlled by a negative feedback loop inMycobacterium marinum
Authors: Bosserman Rachel E. , Nguyen Tiffany T. , Sanchez Kevin G. , Chirakos Alexandra E. , Ferrell Micah J. , Thompson Cristal R. , Champion Matthew M. , Abramovitch Robert B. , Champion Patricia A.
Published: November 2017

Significance

Mycobacteria use ESX systems to transport protein substrates across the cytoplasmic membrane. The ESX-1 system is required for mycobacterial pathogenesis inMycobacterium tuberculosis(M. tb), the cause of tuberculosis (TB). Differences in the expression of genes encoding ESX substrates directly impactsM. tbtransmission and virulence. Deletion of genes encoding ESX exporters results in reduced levels of ESX substrates in mycobacteria. Here, we define a fundamental mechanism of regulation of ESX-1 substrates inM. marinum, a pathogenic mycobacterial species and a model forM. tb. We demonstrate that the transcriptional regulation of genes encoding ESX-1 substrates is linked to the presence or absence of the ESX-1 exporter. These findings provide insight into how substrate levels are intricately controlled in mycobacteria.
Phosphorylation of CENP-C by Aurora B facilitates kinetochore attachment error correction in mitosis
Authors: Zhou Xing , Zheng Fan , Wang Chengliang , Wu Minhao , Zhang Xiaozhen , Wang Qian , Yao Xuebiao , Fu Chuanhai , Zhang Xuan , Zang Jianye
Published: November 2017

Significance

Kinetochores are large protein networks located on centromeres that mediate chromosome segregation during mitosis and maintain genomic stability. Mis12 complex (Mis12C) functions as a scaffold that targets Ndc80 and Knl1 complexes to the centromere by associating with CENP-C. Here, we provide insights into the molecular mechanism underlying the CENP-C–dependent kinetochore recruitment of Mis12C, which is negatively regulated by Aurora B-dependent CENP-C phosphorylation. Replacement of
Schizosaccharomyces pombe
Cnp3 with a phosphorylation-mimicking mutant, Cnp3
T28E
, results in defective chromosome segregation caused by improper kinetochore assembly. These findings indicate that Aurora B-dependent phosphorylation of CENP-C plays a role in interrupting the connection between the inner and outer kinetochore and is thus involved in the error correction/spindle assembly checkpoint pathway to prevent chromosome missegregation during mitosis.
Chiral intertwined spirals and magnetic transition dipole moments dictated by cylinder helicity
Authors: Sato Sota , Yoshii Asami , Takahashi Satsuki , Furumi Seiichi , Takeuchi Masayuki , Isobe Hiroyuki
Published: November 2017

Significance

Defining unique properties of anomalous molecular entities is one of the most important roles of chemistry. Revealed by discovery of carbon nanotubes, rolled sheets of graphitic carbons are among such molecular structures possessing unique chirality. Although the chirality in nanotubes is attracting renewed interest in physical science, our understanding as well as exploration of its utilities is still in its infancy due to scarcity of chiral congeners with discrete structures. In this paper, chirality-originated properties of tubular molecules have been disclosed. The chirality in the cylindrical molecular structure results in chiral double helices in crystals and in extremely large dissymmetry factors associated with circularly polarized light. Cylinder chirality would be characteristic features to be explored in materials science of tubular structures.
Bartolomé de las Casas and the Spanish-American War
Authors: Valdeón Roberto A.
Published: November 2017

This article explores the uses of Las Casas’s Brevísima relación de la destrucción de las Indias in the United States of America, with a focus on the Spanish-American War. After introducing the concept of the Black Legend and its use in England, Spain’s main rival in the Americas during the early modern period, I briefly discuss the first two English translations of the tract by Las Casas. The ideological manipulation carried out by M. M. S. and by John Phillips set the tone for the future use of Las Casas as part of the anti-Spanish propaganda characteristic of Renaissance England first and of modern America later. I then proceed to examine how the narrative ascribed to Las Casas has contributed to forge an anti-Spanish feeling in the US, evident in the years before and after the Spanish-American War of 1898. This section suggests that Las Casas’s text was violated in many ways in order to support a narrative of hatred, as shown in the sermons of American Protestant ministers, books, and, above all, in the 1898 US edition of his work.