bluuebunny/crossref_metadata_2025 huggingface dataset:
Hochleistungs‐Hybridbausystem mit Holz und Stahl
Authors: Müller Andreas , Geyer Christoph , Hausammann Roman
Published: March 2020

In nur fünf Monaten wurde in Lenzburg (CH) mit einem neu entwickelten Hochleistungs‐Hybridbausystem ein energieeffizientes Mehrfamilienhaus mit 20 preisgünstigen Mietwohnungen realisiert.

Das Prinzip des Hochleistungs‐Hybridbausystems sieht bezugsfertig hergestellte kubische Wohnraummodule aus einer Holzleichtbaukonstruktion vor, welche auf der Baustelle in eine vorgängig montierte Stahlskelettkonstruktion eingefügt werden. Im Gegensatz zur üblichen Raummodulbauweise, bei der die Module aufeinandergestapelt werden, konnten durch das Entwurfsprinzip der sich selbst tragenden Holzbaumodule die Wanddicken reduziert und damit wesentlich materialoptimiert werden. Die Stahlskelettkonstruktion ermöglicht, die Wanddicke der Stahlhohlprofile optimal auf die Anzahl der Geschosse anzupassen. Die Stahlskelettstützen bleiben in ihren Außenabmessung bei vier‐ bis achtgeschossigen Gebäuden immer gleich und ermöglichen eine max. Standardisierung bei der Detailausbildung. Eines der Schlüsselelemente der Entwicklungsarbeit war die konsequent ausgebildete Schallentkopplung zwischen Wohnraummodul und Stahlskelett. Sämtliche Auflagerdetails, Stabilisierungsanschlüsse und Verbindungen zwischen Modul und Skelett sind durch Elastomerlager schalltechnisch entkoppelt.
The de‐coders: A historical perspective of the genetic counseling profession
Authors: Cohen Leslie
Published: March 2020

The genetic counseling profession is a relatively new medical specialty that has evolved over time in keeping with advanced in the medical genetics field. Genetic counselors are master's‐level trained individuals who apply their skills to assist patients in understanding the genetic etiology of disease, assessing risk for genetic disease, and providing support to those who are encountering a genetic disorder in themselves or family member. Formal training of genetic counselors began nearly 50 years, and since then, the field has been expanding and advancing. Defining the tenets and practice of the genetic counseling profession has also similarly changed over time; however, the core guiding principles of the profession have remained rooted in the concept of patient autonomy and client‐centered care. Competency in the field is achieved by successfully graduating from an accredited master's‐level training program in which the curriculum is based on standards set forth by the Accreditation Council of Genetic Counseling. Curricula are developed so that trainees are exposed to didactic work, hands‐on clinical fieldwork, and research so that at the end of one's training they have become competent in The Practice Based Competencies that have been established for the profession. Upon graduation, genetic counselors find themselves working in a number of professional settings and subspecialties in genetics. As the underlying genetic cause of disease has become clearer, the areas in which genetic counselors practice have expanded and allows for diverse clinical practice. The profession has, and will, continue to adapt along with the advances in molecular genetics.
Cytogenetic and molecular diagnostic testing associated with prenatal and postnatal birth defects
Authors: Berisha Stela Z. , Shetty Shashi , Prior Thomas W. , Mitchell Anna L.
Published: March 2020

Genetic testing is beneficial for patients and providers when in search of answers to medical problems related to the prenatal or early postnatal period. It can help to identify the cause or confirm a diagnosis associated with developmental delay, intellectual disability, dysmorphic features, heart defects, multiple malformations, short stature, stillbirth, neonatal death, or fertility problems. Genetic testing can be used to rule out single‐gene or chromosome abnormalities. Different diagnostic cytogenetic and molecular genetic techniques are applied in clinical genetics laboratories, from conventional ones to the state of the art chromosomal microarrays and next‐generation sequencing. Each of the genetic techniques or methods has its strengths and limitations, however different methods complement each‐other in trying to identify the genetic variation(s) responsible for a medical condition, especially the ones related to birth defects.
Mandatory newborn screening in the United States: History, current status, and existential challenges
Authors: McCandless Shawn E. , Wright Erica J.
Published: March 2020

Beginning in the 1960s, mandatory newborn screening (NBS) of essentially all infants has been a major public health success story. NBS is not just a blood test, rather, it is a complex, integrated system that begins with timely testing, scrupulous follow up of patients, tracking of outcomes, quality improvement of all aspects of the process, and education of providers, staff, and parents. In the past, expansion of NBS programs has been driven by new testing technology, but now is increasingly driven by the development of novel therapeutics and political advocacy. Each state determines how the NBS system will be structured in that state, but there is increasing oversight and support for harmonization at a federal level. Several recent initiatives, together with the increased number of conditions screened and the concomitant increase in burdensome false‐positive tests, are creating new scrutiny of NBS systems, and potentially pose an existential risk to the public acceptance of mandatory NBS. The history, current state and challenges for NBS are explored in this issue, with some suggestions as to how to address them.
The effectiveness of a special school experience for improving preservice teachers’ efficacy to teach children with special educational needs and disabilities
Authors: Coates Janine K. , Harris Jo , Waring Michael
Published: March 2020

Increasingly, preservice teachers are required to demonstrate their ability to effectively cater for the needs of a diverse range of learners, including those with special educational needs and disabilities (SEND). Higher education institutions (HEI) delivering teacher education programmes are responsible for promoting the development of inclusive practices. This multi‐method study assessed the effectiveness of a special school experience for preservice teachers at one HEI in England. A total population sample of 48 preservice teachers completed self‐efficacy questionnaires at three time points during their training; and 13 took part in qualitative semi‐structured interviews towards the end of the study. Analysis of variance (ANOVA) findings from the questionnaire data showed that the experience had a significant positive impact on preservice teachers’ self‐efficacy, improving knowledge, understanding and confidence to teach inclusively. A thematic analysis of the qualitative findings revealed that the experience challenged preservice teacher expectations about learners with SEND, developing understanding about learner needs and effective differentiation. This article concludes with recommendations for effective inclusion training for preservice teachers.
Evaluierung der dynamischen Systemeigenschaften von einfeldrigen Stahlbeton‐Eisenbahnbrücken
Authors: Vospernig Michael , Reiterer Michael
Published: March 2020

Dynamische Berechnungen von Zugüberfahrten für kurze einfeldrige Eisenbahnbrücken führen oft zu einem Überschätzen der Tragwerksantwort im Resonanzfall. Bei Vergleichsmessungen an realen Stahlbetontragwerken kann festgestellt werden, dass dynamische Kenngrößen wie die Eigenfrequenzen und die Lehrschen Dämpfungen von den Vergleichsgrößen im Rechenmodell stark abweichen. Nach Einbeziehung der messtechnisch ermittelten dynamischen Kenngrößen in das Rechenmodell können die dynamischen Nachweise sehr oft positiv geführt werden. Zur Erzielung einer besseren Übereinstimmung von Messung und Berechnung werden in der gegenständlichen Untersuchung an zwei Versuchsbrücken die dynamischen Kenngrößen im Zuge einer Messkampagne bei unterschiedlichen Ausbauzuständen ermittelt. Dabei liegt das Hauptaugenmerk darauf, die Steifigkeit und Systemdämpfung beeinflussenden Parameter abzuleiten, die mit der Bauform der Versuchsbrücken in Verbindung stehen. An den beiden Versuchsbrücken, in Form von einfeldrigen Stahlbetonplatten, werden Messungen der Tragwerksantwort mit der krafterregten Schwingungsanregungsmethode durchgeführt, wobei ein Tragwerk im ungerissenen und eines im gerissenen Zustand untersucht wird. Die Änderungen der dynamischen Kenngrößen infolge Ausbaulasten, temperaturbedingter jahreszeitlicher Schwankungen und Konstruktionsdetails werden dokumentiert und Vorschläge für die Anpassung in der Modellierung für die dynamischen Berechnungen werden angeführt.
Two life prediction models for optoelectronic displays without conventional life tests
Authors: Zhang Jianping , Chen Siyi , Zong Yu , Li WenBin , Wu Helen
Published: March 2020

To precisely predict the life of optoelectronic displays over a short time, two life prediction models were established based on the three‐parameter Weibull right approximation method (TPWRAM). In Model I, the acceleration life under each stress was obtained using TPWRAM, the data points formed by acceleration life and acceleration stress were, respectively, fitted by three extrapolation functions and the optimal extrapolation function was determined by comparing the fitting determination coefficient and root‐mean‐square error. In Model II, after introducing an acceleration parameter, the luminance attenuation data under conventional stress were calculated directly by combining the ones obtained using TPWRAM under each acceleration stress. The luminance attenuation test data from the vacuum fluorescent display (VFD) were collected through four groups of constant‐stress accelerated degradation tests (ADT), and the two models were applied to the life prediction of VFD. The results indicated that the designed ADT scheme was feasible, Model I revealed the changing law of life with stress and simplified the process of life prediction, and Model II made it possible to obtain the luminance attenuation formula at conventional stress without conducting a conventional life test, overcoming the shortcomings of long time‐consuming traditional life tests. It was verified by comparing the life prediction values that the two models had very high precision, and both of these not only achieve the accurate estimation of optoelectronic product life without resorting to conventional life test, but also improved the method of life prediction and perfect its theoretical system.
Application of community detection algorithms on learning networks. The case of Khan Academy repository
Authors: Yassine Sahar , Kadry Seifedine , Sicilia Miguel‐Angel
Published: March 2020

The rapid development of online learning networks has resulted in the widespread use of recorded educational contents. While the community structure of those networks may have an influence on the use of contents, research on detecting online learning communities and investigating their structures using social network analysis (SNA) methods is scarce. The purpose of the research presented here is to investigate the structure of online learning networks and their users’ engagement patterns. In this study, Khan Academy, a widely used video learning repository, will be used as a case. Community detection algorithms are used to detect the development of online learning communities and network performance and effectiveness measures are applied to assess the network structure, effectiveness, and efficiency of a large dataset consisting of 359,163 users that interacted with Khan Academy's videos with over 3M questions and answers. The results demonstrate that different community detection algorithms can be implemented on learning networks and produce good learning communities which are not necessarily related to a domain or a topic. Measures such as density can be used to measure social presence while centrality measures are used to define central users and hubs in the communities. This study complements previous research that shed the light on the power and potential of SNA measures to structurally evaluate and detect online learning communities.
Does the number of perpetrators matter? An extension and re‐analysis of workplace bullying as a risk factor for exclusion from working life
Authors: Glambek Mats , Skogstad Anders , Einarsen Ståle Valvatne
Published: March 2020

Based on a nationally representative sample (N = 1,613) and a true prospective design, we show that the link between self‐labelled workplace bullying and exclusion from working life (i.e., becoming a non‐participant in working life) over a 5‐year time lag becomes stronger with increasing numbers of perpetrators involved. The amount of exposure to bullying behaviours could not explain the added effect of multiple perpetrators, indicating that the presence of multiple perpetrators is significant in and of itself. A post hoc descriptive cross‐tabulation analysis also showed that when one or two perpetrators were involved at T1, the rate of exclusion from working life 5 years later did not differ substantially from the normal population's exclusion rate. When three or more perpetrators were involved, on the other hand, the exclusion rate approached 50%, indicating that ≥3 perpetrators could denote a critical cut‐off point for a distinguishable group‐bullying phenomenon, at least with respect to exclusion from working life.
A novel augmented reality framework based on monocular semi‐dense simultaneous localization and mapping
Authors: Wu Lianyao , Wan Wanggen , Yu Xiaoqing , Ye Chunkai , Muzahid A A M
Published: March 2020

Markerless tracking has been a trend in augmented reality (AR) applications nowadays, but it no longer satisfies users who want virtual characters to interact with the real world such as collision. Some sparse or dense simultaneous localization and mapping (SLAM) methods are proposed aiming to solve this problem. However, sparse methods only extract a plane from the sparse map, which cannot allow virtual characters to move realistically. Meanwhile, dense methods usually require powerful graphics processing unit (GPU) for dense mapping. In this paper, we present a real‐time AR framework based on a semi‐dense method with central processing unit (CPU). Specifically, the semi‐dense method searches pixels with high gradients in each keyframe and estimates accurate depths by fusing matching pixels in other keyframes. We propose an outlier removal method that excludes three‐dimensional points outside the camera trajectory. By integrating this method, our framework preserves clean edges of the real environment. The experimental results on the dataset show that our proposed framework has better surface reconstruction accuracy than other methods and our tracking thread runs in an acceptable speed when the semi‐dense mapping thread runs backend. With the benefit of the robust camera tracking and the aligned surface, virtual characters of our AR application enable realistic movement and collision.
IRF2‐INPP4B axis inhibits apoptosis of acute myeloid leukaemia cells via regulating T helper 1/2 cell differentiation
Authors: Zhang Feng , Zhu Kai , Liu Lin , Zhu Junfeng , Li Jiajia , Zhang Pingping , Hu Zhongli , Yuan Yuan
Published: March 2020

The interferon‐regulatory factor 2 (IRF2)‐inositol polyphosphate‐4‐phosphatase type‐II (INPP4B) axis has been shown to suppress cell apoptosis by inducing autophagy in acute myeloid leukaemia (AML) cells. T helper type 1 cell (Th1)/Th2 imbalance is involved in development of autophagy and AML. The aim of this study was to investigate whether IRF2‐INPP4B axis regulates autophagy and apoptosis of AML cells via regulating Th1/Th2 cell differentiation. The frequencies of Th2 cells and Th1 cells in transfected CD4+ T cells were determined by flow cytometry. The levels of TNF‐α, IFN‐γ, IL‐4, and IL‐13 in peripheral blood and transfected CD4+ T cells from AML patients and healthy donors were examined by ELISA assay. The mRNA levels of IRF2 and INPP4B in peripheral blood mononuclear cells (PBMCs) from AML patients and healthy donors were detected by qRT‐PCR. Autophagy was evaluated by green fluorescent protein (GFP)‐LC3 immunofluorescence and western blot analysis of autophagy‐associated proteins. AML cell apoptosis was detected by flow cytometry. In this study, elevated frequencies of Th2 cells and reduced frequencies of Th1 cells, as well as higher expression of IRF2 and INPP4B, were observed in PBMCs from AML patients relative to healthy donors. Furthermore, IRF2 inhibited Th1 cell differentiation and promoted Th2 cell differentiation through INPP4B. Moreover, we confirmed that IRF2‐INPP4B–mediated regulation of Th1/Th2 differentiation promoted autophagy and inhibited apoptosis of AML cells. Collectively, IRF2‐INPP4B axis regulates autophagy and apoptosis of AML cells via regulating Th1/Th2 cell differentiation.

Significance of the study

In the present study, we confirmed that IRF2‐INPP4B–mediated regulation of Th1/Th2 balance promoted autophagy and inhibited apoptosis of AML cells. These findings might provide clues in better understanding of the mechanisms of AML.
Mitral regurgitation in patients undergoing transcatheter aortic valve implantation for degenerated surgical aortic bioprosthesis: Insights from PARTNER 2 Valve‐in‐Valve Registry
Authors: Murdoch Dale J. , Sathananthan Janarthanan , Hensey Mark , Alu Maria C. , Liu Yangbo , Crowley Aaron , Wood David , Cheung Anson , Ye Jian , Feldman Ted , Hahn Rebecca T , Jaber Wael A. , Mack Michael J. , Malaisrie S Chris , Leon Martin B. , Webb John G.
Published: March 2020

Background

Valve‐in‐valve (VIV) treatment with transcatheter aortic valve replacement (TAVR) is a viable option for patients with failing aortic bioprosthetic valves. Optimal management of those with concomitant mitral regurgitation (MR) remains undetermined. Therefore, we sought to assess the implications of concomitant MR in patients undergoing VIV‐TAVR.

Methods and Results

The PARTNER 2 VIV registry enrolled patients with degenerated surgical aortic bioprosthesis at high risk for reoperation. Patients with core‐laboratory echocardiographic assessment of MR were analyzed; severe MR was excluded. We compared patients with ≤mild MR versus moderate MR and assessed changes in MR severity and clinical outcomes.

A total of 339 patients (89 initial registry, 250 continued access) underwent VIV procedures; mean age 79.0 ± 10.2 years, mean Society of Thoracic Surgeon score 8.9 ± 4.5%. At baseline, 228/339 (67.3%) had ≤mild MR and 111/339 (32.7%) had moderate MR. In paired analysis, there was significant improvement in ≥moderate MR from baseline to 30 days (32.6% vs. 14.5%, p < .0001 [n = 304]), and no significant change between 30 days and 1 year (13.4% vs. 12.1%, p = .56 [n = 224]) or 1 year and 2 years (11.0% vs. 10.4%, p = .81 [n = 182]). There was no difference in death or stroke between ≤mild MR and moderate MR at 30 days (4.0% vs. 7.2%, p = .20), 1 year (15.5% vs. 15.3%, p = .98) or 2 years (26.5% vs. 23.5%, p = .67).

Conclusion

Moderate concomitant MR tends to improve with VIV‐TAVR, and was not a predictor of long‐term adverse outcomes in this cohort. In selected patients undergoing VIV‐TAVR, it may be appropriate to conservatively manage concomitant MR.

Clinical Trial Registration

ClinicalTrials.gov NCT# 03225001.
One‐Dimensional MnO2 Nanowires Space‐Confined in Hollow Mesoporous Carbon Nanotubes for Enhanced Zn2+ Storage Performance
Authors: Liu Weifang , Liu Penggao , Hao Rui , Huang Yanping , Chen Xinxin , Cai Ruizheng , Yan Jun , Liu Kaiyu
Published: March 2020

The yolk‐shell structure exhibits fascinating and important properties for energy storage devices. The carbon shell significantly improves the good electrical conductivity and the stable micro‐/nanostructures of the active material increases utilization. MnO2@C with a yolk‐shell structure shows high reversibility, good rate performance, and excellent cycling stability for aqueous Zn‐ion batteries. The Zn‐ion battery with MnO2@C could realize a high reversible capacity of 239 mAh g−1 at 0.1 A g−1. In particular, at a quite high current density of 2 A g−1, it achieves capacity of 91 mAh g−1. The Zn‐ion battery has excellent capacity retention of up to 1000 cycles at 1 A g−1. The yolk‐shell structure plays an important role in improving the battery performance.
Enhanced Energy Storage of Fe3O4 Nanoparticles Embedded in N‐Doped Graphene
Authors: Chauque Susana , Braga Adriano H. , Gonçalves Renato V. , Rossi Liane M. , Torresi Roberto M.
Published: March 2020

We report the synthesis and application of a material composed of Fe3O4 nanoparticles embedded in N‐doped graphene sheets (Fe3O4@N‐doped graphene) as a negative electrode for Li batteries. We study the influence of N‐doped graphene on the storage capacity of Fe3O4 using different electrochemical techniques. The as‐prepared Fe3O4 materials presented high‐quality crystalline nanostructures. The N‐doped graphene sheets improve the conductivity between the Fe3O4 nanoparticles, allowing a faster charge transfer process than that for pure magnetite, as well as the presence of porous particles in the hybrid composite. The Fe3O4@N‐doped graphene material show the best Li storage capacity maintaining specific capacity values of 910 mA h g−1 during 150 cycles performed at 0.05 A g−1 and 850 mA h g−1 at 0.1 A g−1 during the following 50 cycles. The N‐doped graphene sheets resist the volume changes that occur during cycling processes in rate capability experiments. We provide a simple and novel method to obtain a material with a higher superficial area and conductivity between particles, allowing great performance as a negative electrode for Li batteries application.
Synthesis, Structure, Solid‐State NMR Spectroscopy, and Electronic Structures of the Phosphidotrielates Li3AlP2 and Li3GaP2
Authors: Restle Tassilo M. F. , Dums Jasmin V. , Raudaschl‐Sieber Gabriele , Fässler Thomas F.
Published: March 2020

The lithium phosphidoaluminate Li9AlP4 represents a promising new compound with a high lithium ion mobility. This triggered the search for new members in the family of lithium phosphidotrielates, and the novel compounds Li3AlP2 and Li3GaP2, obtained directly from the elements via ball milling and subsequent annealing, are reported here. It was unexpectedly found through band structure calculations that Li3AlP2 and Li3GaP2 are direct band gap semiconductors with band gaps of 3.1 and 2.8 eV, respectively. Rietveld analyses reveal that both compounds crystallize isotypically in the orthorhombic space group Cmce (no. 64) with lattice parameters of a=11.5138(2), b=11.7634(2) and c=5.8202(1) Å for Li3AlP2, and a=11.5839(2), b=11.7809(2) and c=5.8129(2) Å for Li3GaP2. The crystal structures feature TrP4 (Tr=Al, Ga) corner‐ and edge‐sharing tetrahedra, forming two‐dimensional
layers. The lithium atoms are located between and inside these layers. The crystal structures were confirmed by MAS‐NMR spectroscopy.
Dehydropolymerisation of Methylamine Borane and an N‐Substituted Primary Amine Borane Using a PNP Fe Catalyst
Authors: Anke Felix , Boye Susanne , Spannenberg Anke , Lederer Albena , Heller Detlef , Beweries Torsten
Published: March 2020

Dehydropolymerisation of methylamine borane (H3B⋅NMeH2) using the well‐known iron amido complex [(PNP)Fe(H)(CO)] (PNP=N(CH2CH2PiPr2)2) (1) gives poly(aminoborane)s by a chain‐growth mechanism. In toluene, rapid dehydrogenation of H3B⋅NMeH2 following first‐order behaviour as a limiting case of a more general underlying Michaelis–Menten kinetics is observed, forming aminoborane H2B=NMeH, which selectively couples to give high‐molecular‐weight poly(aminoborane)s (H2BNMeH)n and only traces of borazine (HBNMe)3 by depolymerisation after full conversion. Based on a series of comparative experiments using structurally related Fe catalysts and dimethylamine borane (H3B⋅NMe2H) polymer formation is proposed to occur by nucleophilic chain growth as reported earlier computationally and experimentally. A silyl functionalised primary borane H3B⋅N(CH2SiMe3)H2 was studied in homo‐ and co‐dehydropolymerisation reactions to give the first examples for Si containing poly(aminoborane)s.
Controlling the Depolymerization of Paraformaldehyde with Pd–Phosphine Complexes
Authors: Geitner Robert , Weckhuysen Bert M.
Published: March 2020

Paraformaldehyde is an easy‐to‐handle chemical for the in situ generation of formaldehyde and is, therefore, often used in chemistry, structural biology, or medicine. We have investigated the depolymerization process of paraformaldehyde at different temperatures for the application as C1 surrogate in “CO‐free” carbonylation reactions using in situ Raman spectroscopy. Rather surprisingly, it was found that small amounts of commonly applied carbonylation catalysts slow down the depolymerization process significantly. By applying 1H, 17O, and 31P NMR spectroscopy coupled with DFT calculations the inhibition process could be assigned to an electron‐withdrawing coordination behavior of the Pd complex at the chain end of the paraformaldehyde chain. This inhibition process can be controlled by the utilized phosphine ligand.
Doublet Chirality Transfer and Reversible Helical Transition in Poly(3,5‐disubstituted phenylacetylene)s with Pyrene as a Probe Unit†
Authors: Wang Sheng , Feng Xuanyu , Zhang Jie , Wan Xinhua
Published: March 2020

Summary of main observation and conclusion

A novel doublet chirality transfer (DCT) model was demonstrated in cis poly(3,5‐disubstituted phenylacetylene)s, i.e., S‐I, R‐I, and S‐I‐NMe. The chiral message from the stereocenter of alkylamide substituent at 3‐position induced the polyene backbone to take cis‐transoid helical conformation with a predominant screw sense. And in turn the helical backbone acted as a scaffold to orient the pyrene probes, which was linked to phenyl rings through 5‐position, to array in an asymmetric manner. A combinatory analyses of 1H NMR, Raman, FTIR, UV‐vis absorption, CD, and computer simulation suggested that the main‐chain stereostructure, solvent nature, and intramolecular hydrogen bonds played important and complex roles on DCT. High cis‐structure content and intramolecular hydrogen bonds were beneficial for the realization of DCT. Reversible helix‐helix transition was observed in S‐I by changing the nature of solvents. In DMF, S‐I adopted a relatively contracted helix, where the main chain exhibited strong optical activity, but that of pyrene was weak. In contrast, a relatively stretched helix formed in CHCl3, in which the optical activity of pyrene was much larger, whereas that of the polyene backbone was the weakest. This helix‐helix transition was attributed to the intramolecular hydrogen bonds, which was confirmed by solution‐state FTIR spectra and computer calculations.
Asymmetric Disulfanylbenzamides as Irreversible and Selective Inhibitors of Staphylococcus aureus Sortase A
Authors: Barthels Fabian , Marincola Gabriella , Marciniak Tessa , Konhäuser Matthias , Hammerschmidt Stefan , Bierlmeier Jan , Distler Ute , Wich Peter R. , Tenzer Stefan , Schwarzer Dirk , Ziebuhr Wilma , Schirmeister Tanja
Published: March 2020

Staphylococcus aureus is one of the most frequent causes of nosocomial and community‐acquired infections, with drug‐resistant strains being responsible for tens of thousands of deaths per year. S. aureus sortase A inhibitors are designed to interfere with virulence determinants. We have identified disulfanylbenzamides as a new class of potent inhibitors against sortase A that act by covalent modification of the active‐site cysteine. A broad series of derivatives were synthesized to derive structure‐activity relationships (SAR). In vitro and in silico methods allowed the experimentally observed binding affinities and selectivities to be rationalized. The most active compounds were found to have single‐digit micromolar Ki values and caused up to a 66 % reduction of S. aureus fibrinogen attachment at an effective inhibitor concentration of 10 μM. This new molecule class exhibited minimal cytotoxicity, low bacterial growth inhibition and impaired sortase‐mediated adherence of S. aureus cells.
Regioselective C−H Functionalization of Naphthalenes: Reactivity and Mechanistic Insights
Authors: Prévost Sébastien
Published: March 2020

Naphthalene is a very important skeleton in chemistry as evidenced by the large number of active compounds that contain it. For this reason, methods that can achieve easy functionalization of naphthalene derivatives are of great importance. This Minireview summarizes reactions that allow regioselective functionalization of 1‐substituted naphthalenes based on directed C−H activation strategies. Indeed, over the past ten years, many research groups have tried to develop new methodologies to directly introduce different functional groups on every position of naphthalene. In addition to the possible reactions reported in the literature, special attention has been paid to mechanistic aspects in order to explain the observed regioselectivities.
Rapid Depolymerization of Decrystallized Cellulose to Soluble Products via Ethanolysis under Mild Conditions
Authors: Tyufekchiev Maksim , Ralph Katherine , Duan Pu , Yuan Shichen , Schmidt‐Rohr Klaus , Timko Michael T.
Published: March 2020

Efficient cellulose depolymerization is a major bottleneck for economical production of second‐generation biofuels. In this work, crystalline cellulose was subjected to sequential ball milling and ethanolysis as a mild and selective depolymerization approach. Ball milling and ethanolysis resulted in 38±1 % cellulose conversion, with 24 % ethyl‐glucopyranoside as the main identified and quantified product and negligible side reaction of the ethanol solvent to form diethyl ether. In comparison, ethanolysis of the original cellulose resulted in only 3±1 % conversion. Additional soluble products from cellulose ethanolysis included carbohydrate isomers and oligomers, differing from the products obtained from hydrolysis. X‐ray diffraction and nuclear magnetic resonance spectroscopy revealed increased crystallinity post‐reaction, retarding further depolymerization. Hot liquid water extracted soluble oligomers from the ethanolyzed cellulose, suggesting formation of a nanoscale barrier of crystalline cellulose that traps soluble products during ethanolysis. Use of cellulose‐swelling co‐solvents and repeated mechanical decrystallization both proved effective at increasing cellulose conversion and soluble product yields. Repeated ball milling and ethanolysis resulted in 62±1 % cellulose conversion. Ethanolysis of decrystallized cellulose has potential for rapid (<2 h) de‐polymerization at mild conditions.
Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth
Authors: Kreissl Julian J. A. , Langsdorf Daniel , Tkachenko Boryslav A. , Schreiner Peter R. , Janek Jürgen , Schröder Daniel
Published: March 2020

Owing to the high abundance and gravimetric capacity (1165.78 mAh g−1) of pure sodium, it is considered as a promising candidate for the anode of next‐generation batteries. However, one major challenge needs to be solved before commercializing the sodium metal anode: The growth of dendrites during metal plating. One possibility to address this challenge is to use additives in the electrolyte to form a protective solid electrolyte interphase on the anode surface. In this work, we introduce a diamondoid‐based additive, which is incorporated into the anode to target this problem. Combining operando and ex situ experiments (electrochemical impedance spectroscopy, optical characterization, and cycling experiments), we show that molecular diamondoids are incorporated into the anode during cycling and successfully mitigate the growth of dendrites. Furthermore, we demonstrate the positive effect of the additive on the operation of sodium‐oxygen batteries by means of increased energy density.
Aminomethyl‐Functionalized Carbon Nanotubes as a Host of Small Sulfur Clusters for High‐Performance Lithium–Sulfur Batteries
Authors: Li Fen , Tao Jiayou , Zou Zhijun , Li Chang , Hou Zhaohui , Zhao Jijun
Published: March 2020

Here we propose an effective strategy to stabilize small sulfur species by using aminomethyl‐functionalized carbon nanotubes (AM‐CNT) without impairing the conductive channel of the carbon nanotube (CNT) cathode. The linear Sn clusters can be anchored strongly to the AM‐CNT for the favorable size of n=5 and the maximum size of n=6 in the production of the cathode, which depresses the mass loss of active sulfur effectively and eliminates the formation of high‐order polysulfides completely during the discharge process. The most stable 3 D cross‐linked Inter‐S5‐AM‐CNT network shows a fast electron transfer redox reaction through the CNT skeleton that possesses a theoretical capacity of 1337 mA h g−1 (based on sulfur) or 592 mA h g−1 (based on the cathode). The discharge products of the linear S5 cluster tend to form a hyperbranched tight structure through N⋅⋅⋅S⋅⋅⋅Li bridges that are fully impregnated in the AM‐CNT bundles, and thus stabilize the entire system. Importantly, this study provides vital guidance into how to design cathodes based on small sulfur clusters for Li‐S batteries to depress the shuttle effect intrinsically during charge–discharge cycles, which can be extended to the other small‐sulfur‐cluster‐based batteries.
Scrape‐off layer width set by non‐linear streamer flows in drift wave turbulence
Authors: Kosuga Y. , Kin F. , Sasaki M.
Published: March 2020

In this work, we discuss the physics behind the excitation of non‐linear streamer flows in drift wave turbulence and how to selectively excite these flows. Streamer flows are modelled as a non‐linear, radially elongated convective cell in drift wave turbulence. It is shown that density modulation is key for exciting streamer flows. We show that streamer flows have a finite frequency, albeit smaller than that of drift waves. Streamers propagate in the ion direction. These theoretical predictions are compared against experimental data, which shows reasonable agreement. Finally, the scrape‐off layer width set by streamer flows is calculated, and a scaling law against macroscopic plasma parameters is obtained.
Enhancing and neutralizing anti‐coxsackievirus activities in serum samples from patients prior to development of type 1 diabetes
Authors: Sane Famara , Bertin Antoine , Sioofy‐Khojine Amir‐Babak , Oikarinen Sami , Alidjinou Enagnon K. , Veijola Riitta , Toppari Jorma , Ilonen Jorma , Knip Mikael , Engelmann Ilka , Hyöty Heikki , Hober Didier
Published: March 2020

Background

Studies in prospective cohorts have suggested that enterovirus infections are associated with the appearance of islet autoantibodies that precede later appearance of type 1 diabetes (T1D). It was shown that in addition to an antibody‐mediated anti‐coxsackievirus (CV)‐B neutralizing activity of serum from patients with T1D, there was also enhancing anti‐CV‐B activity in vitro. In this study, the patterns of enhancing and neutralizing anti‐CV activities were analysed from consecutive serum samples collected from children who were followed from birth until they developed T1D in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study and compared to those in non‐diabetic control children.

Methods

The titres of serum neutralizing activity were analysed against those CVs which were detected in the stools in these children (CV‐B3, CV‐B5 or CV‐A4) using plaque assay. The enhancing activity of these serum samples was analysed by measuring interferon‐alpha (INF‐α) production in cultures of peripheral blood mononuclear cells (PBMC) inoculated with a mixture of these viruses and diluted serum.

Results

A sustained anti‐CV enhancing activity was observed in consecutive serum samples in patients with T1D. The pattern of responses differed between children who developed T1D and control children. In patients, the anti‐CV enhancing activity was predominant or even exclusive over the neutralizing activity, whereas in controls the enhancing and neutralising activities were more balanced or the neutralizing activity was largely predominant.

Conclusions

Evaluating the anti‐enterovirus neutralizing and enhancing activity of serum samples can be useful to investigate further the relationship between enteroviruses and the development of T1D.
Stochasticity in social structure and mating system drive extinction risk
Authors: Leach Damon , Shaw Allison K. , Weiss‐Lehman Christopher
Published: March 2020

As anthropogenic activities continue to threaten species across the globe, many populations have seen dramatic reductions in abundance from historical values. While the underlying causes are varied, such long‐term population declines greatly increase these species’ susceptibility to extinction via stochastic processes. Previous research has established that demographic stochasticity and environmental stochasticity play important roles in extinction risk, but few studies have investigated the role of stochasticity in social dynamics, such as group formation and mating systems. Here, we developed a suite of simulation models incorporating different combinations of stochastic processes, while also varying group size and mating system. Using these models, we evaluated the interacting effects of different mating systems coupled with varied sources of stochasticity on extinction risk. Extinction risk was generally higher for populations with mating systems more dependent on even sex ratios in groups (e.g., monogamy). However, in more flexible mating systems (e.g., polygynandry), stochasticity in the formation of individual groups actually reduced extinction risk in certain scenarios. By identifying the factors most important to the stochastic extinction risk of species with different mating systems and social structures, we provide insight into conservation and management strategies for such species facing population declines.
Maintenance of Borrelia burgdorferi among vertebrate hosts: a test of dilution effect mechanisms
Authors: Halsey Samniqueka J. , Miller James R.
Published: March 2020

A better understanding of the mechanisms through which host diversity can influence reservoir pathogen infection is needed to mitigate disease risk. Efforts may involve computational modeling, especially since it is infeasible to perform large‐scale experimental studies of different host composition scenarios in natural settings. We used individual‐based models to examine how changes in host diversity characterized by differences in host reservoir competency for both Ixodes scapularis and Borrelia burgdorferi can influence the maintenance of the pathogen and subsequent human Lyme disease risk. We simulated 1440 different host communities, with 10 repetitions each, consisting of varying densities of Peromyscus leucopus (white‐footed mouse, 0–50), Tamias striatus (eastern chipmunk, 0–30), Blarina brevicauda (short‐tailed shrew, 0–30), Sciurus carolinensis (eastern gray squirrel, 0–15), and Didelphis virginiana (Virginia opossum, 0–2). We then quantified support for three mechanisms (i.e., vector regulation, encounter reduction, and transmission reduction) through which biodiversity–disease relationships occurred using species richness, Shannon H diversity, and host abundance. For each of the dilution effect mechanisms, host abundance was consistently the best‐supported predictor of disease risk. In our model, a dilution effect occurred via vector regulation and transmission reduction, where increasing both species richness and host abundance reduced both density of nymphs (DON) and density of infected nymphs (DIN). However, if disease risk is measured solely by calculating nymphal infection prevalence (NIP), it may seem that host diversity amplifies disease risk. Understanding the mechanisms through which the wildlife host community influences pathogen transmission cycles in nature will help foster effective control and reduction of disease risk in humans.
The effect of climate on population growth in a cold‐adapted ungulate at its equatorial range limit
Authors: Ruprecht Joel S. , Koons David N. , Hersey Kent R. , Hobbs N. Thompson , MacNulty Daniel R.
Published: March 2020

Climatic changes are affecting the distribution and viability of species worldwide, and the effects may be greatest for heat‐sensitive organisms in populations situated near the species’ equatorial range limit. We studied the population dynamics of a cold‐adapted large herbivore, moose (Alces alces shirasi), in a population located at the extreme southern range limit of the species in Utah, USA, using a long‐term dataset of aerial counts conducted between 1958 and 2013. We used a modeling approach that acknowledges the uncertainty in the number of moose counted. To determine how climate influenced this population, we tested four models corresponding to different hypotheses suggested by previous studies of moose population dynamics: (1) High summer rainfall increases population growth, (2) severe winters reduce population growth, (3) high summer and winter temperatures cause heat stress which reduces population growth, and (4) snow conditions favorable to winter ticks reduce population growth. We then ranked these models against two additional hypotheses that tested the combined effects of the best‐performing models. The best‐supported model included summer rainfall and the number of days with snow cover in late winter, which described the conditions influencing winter tick numbers, a common parasite of moose in the region. Reproductive female ticks drop off their hosts at the end of winter to lay eggs, and fewer ticks survive in years with abundant snow cover. Positive effects of snow and rainfall indicated that moose population growth was higher following summers with more rainfall and late winters with more days of snow cover, the latter because those conditions likely reduced winter tick numbers. In accordance with global patterns in which altered precipitation regimes are influencing the dynamics of many species, the top‐performing model suggested that both summer and winter precipitation acted together to explain the most variation in moose population growth. Our analysis demonstrates the multiple pathways by which climate and population density can affect the dynamics of temperate species living at their equatorial range limits, including potential parasite‐mediated effects.
Species‐specific, age‐varying plant traits affect herbivore growth and survival
Authors: Yang Louie H. , Cenzer Meredith L. , Morgan Laura J. , Hall Griffin W.
Published: March 2020

Seasonal windows of opportunity represent intervals of time within a year during which organisms have improved prospects of achieving life history aims such as growth or reproduction, and may be commonly structured by temporal variation in abiotic factors, bottom‐up factors, and top‐down factors. Although seasonal windows of opportunity are likely to be common, few studies have examined the factors that structure seasonal windows of opportunity in time. Here, we experimentally manipulated host‐plant age in two milkweed species (Asclepias fascicularis and Asclepias speciosa) in order to investigate the role of plant‐species‐specific and plant‐age‐varying traits on the survival and growth of monarch caterpillars (Danaus plexippus). We show that the two plant species showed diverging trajectories of defense traits with increasing age. These species‐specific and age‐varying host‐plant traits significantly affected the growth and survival of monarch caterpillars through both resource quality‐ and quantity‐based constraints. The effects of plant age on monarch developmental success were comparable to and sometimes larger than those of plant‐species identity. We conclude that species‐specific and age‐varying plant traits are likely to be important factors with the potential to structure seasonal windows of opportunity for monarch development, and examine the implications of these findings for both broader patterns in the ontogeny of plant defense traits and the specific ecology of milkweed–monarch interactions in a changing world.
N‐Doping in Precursor Sol: Some Observations in Reference to In Situ‐Grown Carbon Film Electrodes for Supercapacitor Applications
Authors: Chavhan Madhav P. , Basu Debarchan , Singh Aditya , Ganguly Somenath
Published: March 2020

The effect of nitrogen doping in the precursor sol from different nitrogen‐bearing sources on the in situ‐grown carbon film is evaluated for use as an electrode in electrochemical capacitors. The film is developed by the electrospray coating of resorcinol–formaldehyde (RF) sol on carbon fiber paper, serving as the current collector of the capacitor and subsequent curing, solvent removal, and carbonization in situ. Ethylenediamine and melamine are the aliphatic and aromatic hydrocarbonaceous sources, respectively, that are added to RF in separate experiments. The interaction between the electrolyte ions and the electrode surface is enhanced due to the presence of nitrogen and oxygen functional groups, and is analyzed through energy‐dispersive X‐ray spectroscopy, elemental CHNS analysis, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy analyses. At the same time, the difference between the cross‐linking mechanism in the two cases leads to different pore structures at the micro‐ and mesoscales in the carbonized product, as reflected in the scanning electron microscope images and nitrogen adsorption–desorption data. The electrochemical performances of the electrodes are analyzed with regard to the two sets of results, referred earlier, and the relative importance of the pore hierarchy induced by cross‐linking is discussed.
US imperiled species are most vulnerable to habitat loss on private lands
Authors: Eichenwald Adam J , Evans Michael J , Malcom Jacob W
Published: March 2020

To stem the ongoing loss of biodiversity, conservation practitioners must distinguish between effective and ineffective approaches for protecting species habitats. Using Google Earth Engine and 31 years of Landsat images, we quantified changes in the habitats of 24 vertebrates listed under the US Endangered Species Act (ESA) and on the International Union for Conservation of Nature (IUCN) Red List across categories of land ownership (eg federal, state, private) in the continental US that are subject to different conservation‐focused legal restrictions. These estimates exclude changes attributable to agricultural conversion and burned areas. The imperiled species we evaluated lost the least amount of habitat (3.6%) on federal lands, whereas losses on private lands without conservation easements were more than twice as high (8.1%). Differences in annual percent loss before and after ESA listing, and between ESA‐listed and Red List species, indicate that the ESA limited habitat loss and was most effective on federal lands. These results underscore the importance of federal lands in protecting habitat for imperiled species and highlight the need to improve habitat protection on private lands for long‐term conservation.