bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology Tips: Entrance Ramps to the Information Superhighway!
Authors: Goldenberg E. Paul , Manes Michelle A.
Published: November 2020

Can we fly free in cyberspace? Quite possibly. The Internet—the already built portion of the nation's planned information superhighway—is an important asset for teachers in all disciplines. Available resources include free or inexpensive materials and software; electronic mail (e-mail) services; other teachers; and interest groups, such as the Geometry Forum described in November's “Technology Tips.” How do teachers access this wealth of information? We have our computers and our modems, but how do we use them? If the computer must call some other computer halfway across the country—or even across an ocean—will the telephone bills be prohibitive? Not necessarily. Many states and provinces allow teachers to gain access to network services at low—or no!—cost through a local telephone call that connects with the cost-free international network known as the Internet.
Making Connections: Spatial Skills and Engineering Drawings
Authors: Baartmans Beverly Gimmestad , Sorby Sheryl A.
Published: November 2020

Students should study the “geometry of one, two, and three dimensions” and through such study will develop the spatial skills needed in a variety of careers (NCTM 1989, 112). As instructors of geometry, we need to be able to demonstrate to our students the uses of mathematics and its connections to other disciplines. The purpose of this article is to demonstrate the kinds of spatial skills needed by engineers for their work and to suggest activities for the geometry classroom that we have used to help build these skills.
Technology Tips: The Correlation Coefficient and Influential Data Points
Authors: Dessart Donald J.
Published: November 2020

In recent years, it has become very popular in many colleges and universities to evaluate teachers for their effectiveness by having students fill out questionnajres. These questionnaires pose items pertaining to the teacher's effectiveness in teaching and working with students. The students then rank each item from “very good” to “bad” or use some other scale. The totality of the ran kings is an indicator of the teacher's effectiveness.
3-D Graphing, Contour Graphs, Topographical Maps, and Matrices Using Spreadsheets
Authors: Feicht Louis
Published: November 2020

Modern spreadsheets can make powerful mathematical concepts accessible to students at a younger age than ever before. Contours and three–dimensional graphing are topics that were previously reserved until well into the first year of college calculus. Three–dimensional graphing now can be successfully taught to middle school students with the assistance of a computer spreadsheet. This combination of the computer with hands-on activity exposes students to numerical and graphical representations of data on the same spreadsheet “page” and forces them to make connections between the two forms of data.
Exploring the Birthday Problem with Spreadsheets
Authors: Lesser Lawrence M.
Published: November 2020

The “birthday problem” is one of several examples (Shaughnessy 1977, 1992) that illustrate students' tendency to underestimate the probability of an event's occurring at least once.
Assessing True Academic Success: The Next Frontier of Reform
Authors: Kennedy Dan
Published: November 2020

Not everyone will agree with the ideas in this article, but I hope that nobody will reject them as being impossible to implement. Assessment, however we define it, is only a means to an end: the learning of mathematics by all our students. If you suspect that your assessment is getting in the way of that basic goal, then I urge you to tame whatever beast it has become. The success of your students is in your hands–for your assessment is the instrument that defines that success.
Using Financial Headlines and the Internet to Keep Statistics Classes Fresh
Authors: Durkin Marilyn B.
Published: November 2020

Stocks, market, and financial data, and their connection to mathematics.
The Evolving Role of Women in Mathematics
Authors: Simon Marilyn K.
Published: November 2020

Oliver Wendell Holmes proclaimed that history lends a perspective to the way in which we view ourselves and our future. Through most of the history of mathematics, women have been persona non grata. According to Wertheim (1995), the battles that women have faced to break into mathematics parallel the battles that they have faced to break into the clergy. Even today, the notion that mathematics is a masculine pursuit persists, and many can readily cite examples of people whom they know to illustrate this point.
Technology Tips: April 2001
Authors: McMullin Lin , Starnes Daren
Published: November 2020

This month, we bring you some “Technology Tips” that are related to probability and statistics. We begin with a contribution by Bishnu Naraine and Peiyi Zhao: an exploration that uses The Geometer's Sketchpad to discuss the broken-stick problem, which is also known as the spaghetti problem. This totally geometric solution nicely complements the analytic solution of the same problem, given in “The Spaghetti Problem Problem,” by Dennis Ippolito, which appeared on pages 422–26 of the May 2000 issue of the Mathematics Teacher. Next is a feature by Allen Holmes that discusses obtaining an explicit definition for a recursively defined sequence by using the built-in statistics regression ability of graphing calculators to model the equation of the sequence. Then a short program by John Jose for the TI-83 and TI-83 Plus graphing calculator helps investigate the law of large numbers by simulating the results of a simple two-dice experiment. Finally our “Surfing note” features a Web site that is devoted to statistics. It contains many resources for an elementary statistics course.
EMRF: Everyday Rubric Grading
Authors: Stutzman Rodney Y. , Race Kimberly H.
Published: November 2020

Teachers spend considerable time and energy working to clarify and communicate their expectations to students. Those expectations are typically communicated when teachers present assignments. Reinforcing the assignments with an assessment process that narrows the feedback focus can benefit teachers and enrich students. For individual assignments, students really need to know the answers to the following questions: Is my work at an acceptable level? Am I on track to earn the grade to which I aspire in this course? They do not need feedback carved into razor-thin slices to make those determinations. We looked for an alternative that allows us to effectively evaluate responses to rich problems within a standards-based curriculum. We hoped to be able to assess written communication, as well as mathematical computation. Promoting student responsibility with a student-centered system was also important. Ultimately, a revised assessment system, which we have come to call EMRF, emerged.
Composition spécifique, abondance saisonnière et influence des facteurs abiotiques chez les punaises à bouclier [Hemiptera: Pentatomidae] en champ de pois au Québec
Authors: Stirnemann Aurélien , Gagnon Annie-Ève , Labrie Geneviève , Lucas Éric
Published: November 2020

L’augmentation récente des abondances et des aires de répartition des populations de Pentatomidae dans la zone néarctique a commencé à devenir problématique depuis 2013 dans la culture de pois frais au Québec, au Canada. Le manque de connaissance sur ces insectes et d’alternatives à la lutte chimique a conduit à des applications d’insecticides à large spectre dans ces champs. Les objectifs de cette étude visaient à établir la composition spécifique et la dynamique temporelle des Pentatomidae en champ de pois frais cultivés dans le sud du Québec. Pour ce faire, des suivis du nombre de captures par piège à phéromones d’agrégation et par observation visuelle ont été effectués en 2016-2017. La punaise brune (Euschistus servus euschistoides) représente l’espèce dominante (99,4 %) dans les champs de pois du Québec. Les pièges à phéromones capturent davantage d’individus lors des stades végétatifs et à la floraison que lors du stade fructification. Un plus grand nombre d’individus ont été capturés par les pièges à phéromones lorsque la température était plus élevée. Cette étude a permis de mettre en lumière la faible diversité de Pentatomidae dans les champs de pois, justifiant ainsi l’initiation d’un programme de lutte intégrée par un programme de suivi des ravageurs, l’établissement éventuel d’un seuil d’intervention, et le développement de solutions alternatives au traitement phytosanitaire actuel pour la gestion de cette espèce.
Increased processing of SINE B2 ncRNAs unveils a novel type of transcriptome deregulation in amyloid beta neuropathology
Authors: Cheng Yubo , Saville Luke , Gollen Babita , Isaac Christopher , Belay Abel , Mehla Jogender , Patel Kush , Thakor Nehal , Mohajerani Majid H , Zovoilis Athanasios
Published: November 2020

The functional importance of many non-coding RNAs (ncRNAs) generated by repetitive elements and their connection with pathologic processes remains elusive. B2 RNAs, a class of ncRNAs of the B2 family of SINE repeats, mediate through their processing the transcriptional activation of various genes in response to stress. Here, we show that this response is dysfunctional during amyloid beta toxicity and pathology in the mouse hippocampus due to increased levels of B2 RNA processing, leading to constitutively elevated B2 RNA target gene expression and high Trp53 levels. Evidence indicates that Hsf1, a master regulator of stress response, mediates B2 RNA processing in hippocampal cells and is activated during amyloid toxicity, accelerating the processing of SINE RNAs and gene hyper-activation. Our study reveals that in mouse, SINE RNAs constitute a novel pathway deregulated in amyloid beta pathology, with potential implications for similar cases in the human brain, such as Alzheimer’s disease (AD).
Structural insights into the nucleic acid remodeling mechanisms of the yeast THO-Sub2 complex
Authors: Schuller Sandra K , Schuller Jan M , Prabu J Rajan , Baumgärtner Marc , Bonneau Fabien , Basquin Jérôme , Conti Elena
Published: November 2020

The yeast THO complex is recruited to active genes and interacts with the RNA-dependent ATPase Sub2 to facilitate the formation of mature export-competent messenger ribonucleoprotein particles and to prevent the co-transcriptional formation of RNA:DNA-hybrid-containing structures. How THO-containing complexes function at the mechanistic level is unclear. Here, we elucidated a 3.4 Å resolution structure of Saccharomyces cerevisiae THO-Sub2 by cryo-electron microscopy. THO subunits Tho2 and Hpr1 intertwine to form a platform that is bound by Mft1, Thp2, and Tex1. The resulting complex homodimerizes in an asymmetric fashion, with a Sub2 molecule attached to each protomer. The homodimerization interfaces serve as a fulcrum for a seesaw-like movement concomitant with conformational changes of the Sub2 ATPase. The overall structural architecture and topology suggest the molecular mechanisms of nucleic acid remodeling during mRNA biogenesis.
Efficient chromatin accessibility mapping in situ by nucleosome-tethered tagmentation
Authors: Henikoff Steven , Henikoff Jorja G , Kaya-Okur Hatice S , Ahmad Kami
Published: November 2020

Chromatin accessibility mapping is a powerful approach to identify potential regulatory elements. A popular example is ATAC-seq, whereby Tn5 transposase inserts sequencing adapters into accessible DNA (‘tagmentation’). CUT&Tag is a tagmentation-based epigenomic profiling method in which antibody tethering of Tn5 to a chromatin epitope of interest profiles specific chromatin features in small samples and single cells. Here, we show that by simply modifying the tagmentation conditions for histone H3K4me2 or H3K4me3 CUT&Tag, antibody-tethered tagmentation of accessible DNA sites is redirected to produce chromatin accessibility maps that are indistinguishable from the best ATAC-seq maps. Thus, chromatin accessibility maps can be produced in parallel with CUT&Tag maps of other epitopes with all steps from nuclei to amplified sequencing-ready libraries performed in single PCR tubes in the laboratory or on a home workbench. As H3K4 methylation is produced by transcription at promoters and enhancers, our method identifies transcription-coupled accessible regulatory sites.
Evidence-based Guidelines for the Treatment of Helicobacter pylori Infection in Korea: 2020 Revised Edition
Authors: Jung Hye-Kyung , Kang Seung Joo , Lee Yong Chan , Yang Hyo-Joon , Park Seon-Young , Shin Cheol Min , Kim Sung Eun , Lim Hyun Chul , Kim Jie-Hyun , Nam Su Youn , Shin Woon Geon , Park Jae Myung , Choi Il Ju , Kim Jae Gyu , Choi Miyoung ,   Korean College of Helicobacter and Upper Gastrointestinal Research
Published: November 2020

Helicobacter pylori (H. pylori) infection is one of the most common infectious diseases worldwide. Although its incidence is gradually decreasing, about half of the world's population still get infected. H. pylori infection is responsible for substantial gastrointestinal morbidity worldwide. It is the most common cause of gastric and duodenal ulcers as well as gastric cancer. Since the revision of the H. pylori Clinical Practice Guidelines in 2013, the eradication rate of H. pylori has gradually decreased with the use of classical triple therapy, wherein amoxicillin, clarithromycin, and proton pump inhibitors are administered, for 7 days. According to a nationwide randomized controlled study conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research released in 2018, the intention-to-treat eradication rate was only 63.9%, which was due to increased antimicrobial resistance induced by the use of antibiotics, especially clarithromycin. The update of clinical practice guideline for treatment of H. pylori was developed based on evidence-based medicine by conducting a meta-analysis. The draft recommendations were finalized after expert consensus on three recommendations regarding the indication for treatment and eight recommendations on the treatment itself. These guidelines are designed to provide patients, nurses, medical school students, policymakers, and clinicians with clinical evidence to guide primary care and treatment of H. pylori infection. These may differ from current medical insurance standards and will be revised further, if necessary, based on research-based evidence.
Emerging Resistance among Uropathogens: Is Fosfomycin Revival the Best Hope?
Authors: Bhattar Sonali , Shingare Priyanjali , Tigga Richa Anjleen , Qureshi Shariqa , Sharma Vikas
Published: November 2020

Introduction: Increasing bacterial resistance and the non-availability of newer antimicrobial agents have necessitated the re-evaluation of old antimicrobial agents. Although an old antibiotic, Fosfomycin gives a ray of hope as it has a unique property of not sharing structural similarity with other antibiotics and with no cross-resistance. Aim: To retrospectively evaluate the invitro activity of Fosfomycin against Extended-Spectrum Beta-Lactamase (ESBL) producing and Carbapenem Resistant Enterobacteriaceae (CRE). Materials and Methods: The study period was from December 2018 to November 2019. Antibiotic sensitivity was carried out according to the Clinical and Laboratory Standards Institute (CLSI) guidelines using the automated Vitek-2 Compact (Bio-Merieux, France). Fosfomycin susceptibility was determined by E-test (Biomereiux, India). The interpretive criteria according to CLSI for Fosfomycin is given only for E.coli and not for other Enterobacteriaceae, hence the results were interpreted as per CLSI criteria given for E. coli (i.e., susceptibility at a Minimum Inhibitory Concentration (MIC) of ≤64 μg). Results: Overall, 91.07% (102/112) isolates were susceptible to Fosfomycin with 91.67% (88/96) susceptibility for ESBL producing Enterobacteriaceae and 87.5% (14/16) for CRE. Fosfomycin has shown good invitro activity against ESBL producers as well as CRE. Conclusion: Fosfomycin showed promising results as a re-emerging antibiotic for the treatment of Urinary Tract Infection (UTI) because of its unique mechanism of action, low incidence of resistance, oral availability with single-dose administration and little tendency to display cross-resistance to other antibiotics.
Stability Analysis of Rice (Oryza sativa L.) Genotypes with High Grain Zinc in Five Different Locations of Eastern Uttar Pradesh
Authors: Singh S. K. , Behera Partha Pratim , Singh D. K. , Korada Mounika , Habde Sonali Vijay , Khaire Amrutlal
Published: November 2020

Rice is a major energy source food crop and a staple food for more than half of the world’s population. The knowledge of mean performance and stability of high grain Zinc rice genotypes  from a multi-location trial is a way to assess the genotypes so as to achieve food and nutritional security. The present research was conducted to study the stability of 21 high grain Zinc rice genotypes for thirteen yield and yield attributing traits in RCBD with 3 replications in five different locations of Eastern Uttar Pradesh using the Eberhart and Russell stability model. Based on the environmental index, Bhikaripur village is identified as the most favourable environment. The inspection of stability and ANOVA revealed that there were significant linear G x E interactions for most of the characters studied expect plant height, spikelet fertility % and total effective tiller number which implied that there were significant variations among the genotypes. The environment + (genotype x environment) was significant for most of the traits except grain L/B ratio representing specific nature of environments and G x E interaction in morphological expression. Based on the stability parameters none of the genotypes could be identified as stable for any traits over the five environments but, IR 97443-11-2-1-1-1-1 –B and Local check (HUR3022) showed stability for high yield in all the environments. The genotype, IR 97443-11-2-1-1-1-1 –B having stability for grain yield per ha with higher mean and short duration, is also stable for grain yield per plant, grain weight per panicle and spikelet fertility % and could be used as high yielding cultivar and can be used as a parent in future breeding programs. The genotype, IR 95044:8-B-5-22-19-GBS is having the highest grain Zinc content. High grain zinc with higher yield was reported in BRRIdhan 64 and it is stable for grain zinc content and can be used for Zinc bio-fortification breeding programs to minimize malnutrition to ensure food and nutritional security.
Elevated levels of extracellular vesicles in progranulin‐deficient mice and FTD‐GRN Patients
Authors: Arrant Andrew E. , Davis Skylar E. , Vollmer Rachael M. , Murchison Charles F. , Mobley James A. , Nana Alissa L. , Spina Salvatore , Grinberg Lea T. , Karydas Anna M. , Miller Bruce L. , Seeley William W. , Roberson Erik D.
Published: November 2020

Objective

The goal of this study was to investigate the effect of progranulin insufficiency on extracellular vesicles (EVs), a heterogeneous population of vesicles that may contribute to progression of neurodegenerative disease. Loss‐of‐function mutations in progranulin (GRN) are a major cause of frontotemporal dementia (FTD), and brains from GRN carriers with FTD (FTD‐GRN) exhibit signs of lysosomal dysfunction. Lysosomal dysfunction may induce compensatory increases in secretion of exosomes, EVs secreted from the endolysosomal system, so we hypothesized that progranulin insufficiency would increase EV levels in the brain.

Methods

We analyzed levels and protein contents of brain EVs from Grn–/– mice, which model the lysosomal abnormalities of FTD‐GRN patients. We then measured brain EVs in FTD‐GRN patients. To assess the relationship of EVs with symptomatic disease, we measured plasma EVs in presymptomatic and symptomatic GRN mutation carriers.

Results

Grn–/– mice had elevated brain EV levels and altered EV protein contents relative to wild‐type mice. These changes were age‐dependent, occurring only after the emergence of pathology in Grn–/– mice. FTD‐GRN patients (n = 13) had elevated brain EV levels relative to controls (n = 5). Symptomatic (n = 12), but not presymptomatic (n = 7), GRN carriers had elevated plasma EV levels relative to controls (n = 8).

Interpretation

These data show that symptomatic FTD‐GRN patients have elevated levels of brain and plasma EVs, and that this effect is modeled in the brain of Grn–/– mice after the onset of pathology. This increase in EVs could influence FTD disease progression, and provides further support for EVs as potential FTD biomarkers.
“More is Different:” Synergistic Effect and Structural Engineering in Double‐Atom Catalysts
Authors: Ying Yiran , Luo Xin , Qiao Jinli , Huang Haitao
Published: November 2020

Double‐atom catalysts (DACs) have emerged as a novel frontier in heterogeneous catalysis because the synergistic effect between adjacent active sites can promote their catalytic activity while maintaining high atomic utilization efficiency, good selectivity, and high stability originating from the atomically dispersed nature. In this review, the recent progress in both experimental and theoretical research on DACs for various catalytic reactions is focused. Specifically, the central tasks in the design of DACs—manipulating the synergistic effect and engineering atomic and electronic structures of catalysts—are systematically reviewed, along with the prevailing experimental, characterization, and computational modeling approaches. Furthermore, the practical applications of DACs in water splitting, oxygen reduction reaction, nitrogen reduction reaction, and carbon dioxide reduction reaction are addressed. Finally, the future challenges for DACs are summarized and an outlook on the further investigations of DACs toward heterogeneous catalysis in high‐performance energy and environmental applications is provided.
Is Viral Vector Gene Delivery More Effective Using Biomaterials?
Authors: Wang Yi , Bruggeman Kiara F. , Franks Stephanie , Gautam Vini , Hodgetts Stuart I. , Harvey Alan R. , Williams Richard J. , Nisbet David R.
Published: November 2020

Gene delivery has been extensively investigated for introducing foreign genetic material into cells to promote expression of therapeutic proteins or to silence relevant genes. This approach can regulate genetic or epigenetic disorders, offering an attractive alternative to pharmacological therapy or invasive protein delivery options. However, the exciting potential of viral gene therapy has yet to be fully realized, with a number of clinical trials failing to deliver optimal therapeutic outcomes. Reasons for this include difficulty in achieving localized delivery, and subsequently lower efficacy at the target site, as well as poor or inconsistent transduction efficiency. Thus, ongoing efforts are focused on improving local viral delivery and enhancing its efficiency. Recently, biomaterials have been exploited as an option for more controlled, targeted and programmable gene delivery. There is a growing body of literature demonstrating the efficacy of biomaterials and their potential advantages over other delivery strategies. This review explores current limitations of gene delivery and the progress of biomaterial‐mediated gene delivery. The combination of biomaterials and gene vectors holds the potential to surmount major challenges, including the uncontrolled release of viral vectors with random delivery duration, poorly localized viral delivery with associated off‐target effects, limited viral tropism, and immune safety concerns.
Coherent Electron Transport in Air‐Stable, Printed Single‐Crystal Organic Semiconductor and Application to Megahertz Transistors
Authors: Kumagai Shohei , Watanabe Shun , Ishii Hiroyuki , Isahaya Nobuaki , Yamamura Akifumi , Wakimoto Takahiro , Sato Hiroyasu , Yamano Akihito , Okamoto Toshihiro , Takeya Jun
Published: November 2020

Organic semiconductors (OSCs) have attracted growing attention for optoelectronic applications such as field‐effect transistors (FETs), and coherent (or band‐like) carrier transport properties in OSC single crystals (SCs) have been of interest as they can lead to high carrier mobilities. Recently, such p‐type OSC SCs compatible with a printing technology have been used to achieve high‐speed FETs; therefore, developments of n‐type counterparts may be promising for realizing high‐speed complementary organic circuits. Herein, coherent electron transport properties in a printed SC of a state‐of‐the‐art, air‐stable n‐type OSC, PhC2−BQQDI, by means of variable‐temperature gated Hall effect measurements and X‐ray single‐crystal diffraction analyses in conjunction with band structure calculations, are reported. Furthermore, the SC FET is tested for high‐speed operations, which obtains a cutoff frequency of 4.3 MHz at an operation voltage of 20 V in air. Thus, PhC2−BQQDI is shown as a new candidate for practical applications of SC‐based, organic complementary devices.
Superhydrophilic and Underwater Superoleophobic Poly(propylene) Nonwoven Coated with TiO2 by Atomic Layer Deposition
Authors: Li Chen , Ren Lipei , Liu Xin , Zhang Chunhua , Chen Dongzhi , Xu Weilin , Qin Yong
Published: November 2020

To develop an effective and convenient solution for underwater repelling oil and cleaning up oily water, TiO2 nano‐coating is deposited on the surface of poly(propylene) nonwoven (PPN) by atomic layer deposition (ALD). There is no evident change in the morphologies comparing ALD‐modified PPN with PPN except for thickness. For oils of different densities, such as 1,2‐dichloroethane, methylene chloride, chloroform, carbon tetrachloride, n‐hexane, and petroleum ether, the underwater oil contact angle and underwater oil sliding angle of ALD‐modified PPN range from 152.25° to 156.19° and 5.63° to 8.80°, respectively, exhibiting superior superhydrophilicity and underwater superoleophobicity. Notably, ALD‐modified PPN shows a high chemical stability in different solutions, such as acid, alkali, salt, and polar solvent, which even can slightly improve the underwater superoleophobicity of TiO2 nano‐coating. The excellent underwater anti‐oil property, self‐cleaning property, robust chemical resistance, and easily scaled‐up preparation process of TiO2‐coated PPN suggest great potential for practical applications in the energy, environmental protection, marine anti‐fouling, and microflow control fields.
Elucidating and Mitigating Degradation Processes in Perovskite Light‐Emitting Diodes
Authors: Andaji‐Garmaroudi Zahra , Abdi‐Jalebi Mojtaba , Kosasih Felix U. , Doherty Tiarnan , Macpherson Stuart , Bowman Alan R. , Man Gabriel J. , Cappel Ute B. , Rensmo Håkan , Ducati Caterina , Friend Richard H. , Stranks Samuel D.
Published: November 2020

Halide perovskites have attracted substantial interest for their potential as disruptive display and lighting technologies. However, perovskite light‐emitting diodes (PeLEDs) are still hindered by poor operational stability. A fundamental understanding of the degradation processes is lacking but will be key to mitigating these pathways. Here, a combination of in operando and ex situ measurements to monitor the performance degradation of (Cs0.06FA0.79MA0.15)Pb(I0.85Br0.15)3 PeLEDs over time is used. Through device, nanoscale cross‐sectional chemical mapping, and optical spectroscopy measurements, it is revealed that the degraded performance arises from an irreversible accumulation of bromide content at one interface, which leads to barriers to injection of charge carriers and thus increased nonradiative recombination. This ionic segregation is impeded by passivating the perovskite films with potassium halides, which immobilizes the excess halide species. The passivated PeLEDs show enhanced external quantum efficiency (EQE) from 0.5% to 4.5% and, importantly, show significantly enhanced stability, with minimal performance roll‐off even at high current densities (>200 mA cm−2). The decay half‐life for the devices under continuous operation at peak EQE increases from <1 to ≈15 h through passivation, and ≈200 h under pulsed operation. The results provide generalized insight into degradation pathways in PeLEDs and highlight routes to overcome these challenges.
Defect Suppression in Oriented 2D Perovskite Solar Cells with Efficiency over 18% via Rerouting Crystallization Pathway
Authors: Yang Yi , Liu Cheng , Syzgantseva Olga A. , Syzgantseva Maria A. , Ma Shuang , Ding Yong , Cai Molang , Liu Xuepeng , Dai Songyuan , Nazeeruddin Mohammad Khaja
Published: November 2020

Vertically oriented 2D perovskites exhibit promising optoelectronic properties and intrinsic stability, but their photovoltaic application is still limited by the low power conversion efficiency (PCE) compared to 3D analogs. Here, a new crystallization pathway (RCP) is reported to suppress defects in vertically oriented 2D perovskite caused by its over‐rapid self‐assembly behavior. By controlling the specific adsorption of an ammonium halide additive on different perovskite crystal planes, the dynamic preferred growth of (111) plane is intentionally restrained, and the minority (202) planes emerge as secondary nucleation sites to stimulate the creation of large grains. As the halogen‐regulated deprotonation of ammonium proceeds, the (111) crystal plane gradually recovers its growth dominance, and a vertically oriented 2D perovskite film finally forms with high homogeneity, reduced trap density of states, and desired carrier transport/collection kinetics. Solar cells using RCP‐2D films show a highly reproducible and stable PCE reaching 18.5% with a high fill factor of 83.4%. These findings provide critical missing information on simultaneously achieving highly oriented and less defective 2D perovskite films for excellent device performance.
Development of an Open‐Access and Explainable Machine Learning Prediction System to Assess the Mortality and Recurrence Risk Factors of Clostridioides Difficile Infection Patients
Authors: Ng Yui-Lun , Lo Michelle C. K. , Lee Kit-Hang , Xie Xiaochen , Kwong Thomas N. Y. , Ip Margaret , Zhang Lin , Yu Jun , Sung Joseph J. Y. , Wu William K. K. , Wong Sunny H. , Kwok Ka-Wai
Published: November 2020

Identifying Clostridioides difficile infection (CDI) patients at risk of mortality or recurrence facilitates prevention, timely treatment, and improves clinical outcomes. The aim herein is to establish an open‐access web‐based prediction system, which estimates CDI patients’ mortality and recurrence outcomes and explains machine learning prediction with patients’ characteristics. Prognostic models are developed using four various types of machine learning algorithms and the statistical logistics regression model utilizing over 15 000 CDI patients from 41 hospitals in Hong Kong. The boosting‐based machine learning algorithm gradient boosting machine (GBM) (Mortality AUC: 0.7878; Recurrence AUC: 0.7076) outperforms statistical models (Mortality AUC: 0.7573; Recurrence AUC: 0.6927) and other machine learning algorithms. As the difficulty to interpret complex machine learning results limits their use in the medical area, Shapley additive explanations (SHAP) are adapted to identify which features are crucial to the machine learning models and associate them with clinical findings. SHAP analysis shows that older age, reduced albumin levels, higher creatinine levels, and higher white blood cell count are the most highly associated mortality features, which is consistent with existing clinical findings. The open‐access prediction system for clinicians to assess and interpret the risk factors of CDI patients is now available at https://www.cdiml.care/.
Azobindungsbildung auf Metalloberflächen
Authors: Meng Xiangzhi , Klaasen Henning , Viergutz Lena , Schulze Lammers Bertram , Witteler Melanie C. , Mönig Harry , Amirjalayer Saeed , Liu Lacheng , Neugebauer Johannes , Gao Hong‐Ying , Studer Armido , Fuchs Harald
Published: November 2020

Die Bildung von Azoverbindungen durch Redoxkreuzkupplung von Nitroarenen und Arylaminen, welche in Lösungsmittelchemie herausfordernd ist, wird durch Oberflächenchemie ermöglicht. Die Reaktionsprodukte werden mit einem kryogenen Rastertunnelmikroskop (STM) und per Röntgenphotoelektronenspektroskopie (XPS) analysiert. Durch die Verwendung gut konzipierter Vorläufer, welche eine Amino‐ und eine Nitrofunktion enthalten, werden Azopolymere durch hocheffiziente Nitro‐Amino‐Kreuzkupplung auf der Oberfläche hergestellt. Experimente mit anderen Substraten und Oberflächenorientierungen zeigen, dass die Metalloberfläche einen signifikanten Einfluss auf die Reaktionseffizienz hat. Zudem wurde herausgefunden, dass die Reaktion partiell oxidierter/reduzierter Vorläuferverbindungen in Dimerisierungsreaktionen ebenfalls stattfindet, was Licht auf den Mechanismus wirft, welcher durch DFT‐Berechnungen weiter untersucht wurde.
Hot‐Electron‐Induced Photothermal Catalysis for Energy‐Dependent Molecular Oxygen Activation
Authors: Zhang Wei , Chen Yu , Zhang Gong , Tan Xiao , Ji Qinghua , Wang Zhaowu , Liu Huijuan , Qu Jiuhui
Published: November 2020

Hot electrons activate reactants and reduce the activation energy barrier (Ea) of a reaction through electron donation. However, a comprehensive understanding of the intrinsic driving force of this electron‐donating effect is lacking, let alone the precise manipulation of electron donation processes. Herein, the essential and promotional role of hot electron energy on the electron‐donating effect was elucidated using molecular oxygen activation (MOA) as a model reaction. Through providing an available electron source to the conventional photo‐thermal conversion system, the high energy carried by hot electrons was liberated and greatly enhanced the electron donation towards the LUMO (π*) orbit of O2. The energy was also transferred to O2 and elevated the potential energy surface (PES) of MOA, which was reflected by the enhanced formation of superoxide oxygen anions. As predicted, the Ea of MOA decreased by 45.1 % and exhibited a substantial light dependence, demonstrating that MOA became energy‐efficient due to improved exploitation and conversion of photon energies.
Liquid Nanoparticles: Manipulating the Nucleation and Growth of Nanoscale Droplets
Authors: Wang Ruoxu , Han Fei , Chen Bo , Liu Lingmei , Wang Shaoyan , Zhang Hua , Han Yu , Chen Hongyu
Published: November 2020

By manipulating the nucleation and growth of solid materials, the synthesis of various sophisticated nanostructures has been achieved. Similar methodology, if applied to liquids, could enable the mass‐production and control of ultra‐small droplets at the scale of nanoparticles (10−18 L or below). It would be highly desirable since droplets play a fundamental role in numerous applications. Here we present a general strategy to synthesize and manipulate nanoscale droplets, similar to what has been done to solid nanoparticles in classic solution‐synthesis. It was achieved by a solute‐induced phase separation which initiates the nucleation of droplets from a homogeneous solution. These liquid nanoparticles have great potentials to be manipulated like their solid counterparts, borrowing from the vast methodologies of nanoparticle synthesis, such as burst nucleation, seeded growth, and co‐precipitation. Liquid nanoparticles also serve as a general synthetic platform, to fabricate nanoreactors, drug‐loaded carriers, and other hollow nanostructures with a variety of shell materials.
Dynamic Activation of Adsorbed Intermediates via Axial Traction for the Promoted Electrochemical CO2 Reduction
Authors: Wang Xinyue , Wang Yu , Sang Xiahan , Zheng Wanzhen , Zhang Shihan , Shuai Ling , Yang Bin , Li Zhongjian , Chen Jianmeng , Lei Lecheng , Adli Nadia Mohd , Leung Michael K. H. , Qiu Ming , Wu Gang , Hou Yang
Published: November 2020

Regulating the local environment and structure of metal center coordinated by nitrogen ligands (M‐N4) to accelerate overall reaction dynamics of the electrochemical CO2 reduction reaction (CO2RR) has attracted extensive attention. Herein, we develop an axial traction strategy to optimize the electronic structure of the M‐N4 moiety and construct atomically dispersed nickel sites coordinated with four nitrogen atoms and one axial oxygen atom, which are embedded within the carbon matrix (Ni‐N4‐O/C). The Ni‐N4‐O/C electrocatalyst exhibited excellent CO2RR performance with a maximum CO Faradic efficiency (FE) close to 100 % at −0.9 V. The CO FE could be maintained above 90 % in a wide range of potential window from −0.5 to −1.1 V. The superior CO2RR activity is due to the Ni‐N4‐O active moiety composed of a Ni‐N4 site with an additional oxygen atom that induces an axial traction effect.
Reduktion und Umlagerung eines Bor(I)‐Carbonylkomplexes
Authors: Rang Maximilian , Fantuzzi Felipe , Arrowsmith Merle , Krummenacher Ivo , Beck Eva , Witte Robert , Matler Alexander , Rempel Anna , Bischof Tobias , Radacki Krzysztof , Engels Bernd , Braunschweig Holger
Published: November 2020

Bei der Einelektronenreduktion eines durch eine cyclisches (Alkyl)(amino)carben (CAAC) stabilisierten Arylborylen‐Carbonylkomplexes erfolgt die Bildung eines dimeren Borylketyl‐Radikalanions, bedingt durch eine intramolekulare Arylmigration zum CO Kohlenstoffatom. Computergestützte Analyse liefert Hinweise auf eine radikalanionische [(CAAC)B(CO)Ar].− Zwischenstufe. Weiterführende Reduktion des entstandenen Komplexes liefert ein hoch nukleophiles (Boranyliden)methanolat.
Kinetic Barriers and Microscopic Mechanisms of Noble Gas Adsorption by Nanoporous γ‐Mg(BH4)2 Obtained by Means of Sub‐Second X‐Ray Diffraction
Authors: Dovgaliuk Iurii , Senkovska Irena , Li Xiao , Dyadkin Vadim , Filinchuk Yaroslav , Chernyshov Dmitry
Published: November 2020

Gas adsorption by porous frameworks sometimes results in structure “breathing”, “pores opening/closing”, “negative gas adsorption”, and other phenomena. Time‐dependent diffraction can address both kinetics of the guest uptake and structural response of the host framework. Using sub‐second in situ powder X‐ray diffraction, three intracrystalline diffusion scenarios have been evaluated from the isothermal kinetics of Ar, Kr, and Xe adsorption by nanoporous γ‐Mg(BH4)2. These scenarios are dictated by two possible simultaneous transport mechanisms: diffusion through the intra‐ (i) and interchannel apertures (ii) of γ‐Mg(BH4)2 crystal structure. The contribution of (i) and (ii) changes depending on the kinetic diameter of the noble gas molecule and temperature regime. The lowest single activation barrier for the smallest Ar suggests equal diffusion of the atoms trough both pathways. Contrary, for the medium sized Kr we resolve the contributions of two parallel transport mechanisms, which tentatively can be attributed to the smaller barrier of the migration paths via the channel like pores and the higher barrier for the diffusion via narrow aperture between these channels. The largest Xe atoms diffuse only along 1D channels and show the highest single activation barrier.
Azo bond formation on metal surfaces
Authors: Meng Xiangzhi , Klaasen Henning , Viergutz Lena , Schulze Lammers Bertram , Witteler Melanie C. , Mönig Harry , Amirjalayer Saeed , Liu Lacheng , Neugebauer Johannes , Gao Hong‐Ying , Studer Armido , Fuchs Harald
Published: November 2020

The formation of azo compounds via redox cross‐coupling of nitroarenes and arylamines, challenging in solution phase chemistry, is achieved by on‐surface chemistry. Reaction products are analyzed with a cryogenic scanning tunneling microscope (STM) and X‐ray photoelectron spectroscopy (XPS). By using well‐designed precursors containing both an amino and a nitro functionality, azo polymers are prepared on surface via highly efficient nitro‐amino cross‐coupling. Experiments conducted on other substrates and surface orientations reveal that the metal surface has a significant effect on the reaction efficiency. The reaction was further found to proceed from partially oxidized/reduced precursors in dimerization reactions, shedding light on the mechanism that was studied by DFT calculations.
Supramolecular Bait to Trigger Non‐Equilibrium Co‐Assembly and Clearance of Aβ42
Authors: Wu Te‐Haw , Lai Rai‐Hua , Yao Chun‐Nien , Juang Jyh‐Lyh , Lin Shu‐Yi
Published: November 2020

In living systems, non‐equilibrium states that control the assembly‐disassembly of cellular components underlie the gradual complexification of life, whereas in nonliving systems, most molecules follow the laws of thermodynamic equilibrium to sustain dynamic consistency. Little is known about the roles of non‐equilibrium states of interactions between supramolecules in living systems. Here, a non‐equilibrium state of interaction between supramolecular lipopolysaccharide (LPS) and Aβ42, an aggregate‐prone protein that causes Alzheimer's disease (AD), was identified. Structurally, Aβ42 presents a specific groove that is recognized by the amphiphilicity of LPS bait in a non‐equilibrium manner. Functionally, the transient complex elicits a cellular response to clear extracellular Aβ42 deposits in neuronal cells. Since the impaired clearance of toxic Aβ42 deposits correlates with AD pathology, the non‐equilibrium LPS and Aβ42 could represent a useful target for developing AD therapeutics.
Chiral Molecular Propellers of Triarylborane Ammonia Adducts
Authors: Kemper Michael , Engelage Elric , Merten Christian
Published: November 2020

Chiral molecular propeller conformations have been induced to various triaryl structures including trityl derivatives and triaryl boranes. For borane–amine adducts, such induced propeller chirality has not been reported yet due to the low energy barrier for racemization in common triarylboranes such as B(C6H5)3 or B(C6F5)3. Herein, we demonstrate that point chirality in side chains of chiral triarylborane–ammonia adducts, which feature intramolecular hydrogen bonds in addition to the dative N→B bond, can efficiently be transferred to triarylborane propeller chirality. Employing X‐ray crystallography and ECD/VCD spectroscopy for structural characterizations, we investigate three examples with different steric demands of the incorporated chiral alkoxy side groups. We elucidate the conformational preferences of the molecular propellers. Furthermore, we show that computationally predicted conformational preferences obtained for the isolated, only implicitly solvated molecules are actually opposite to the experimentally observed ones.
Reduction and Rearrangement of a Boron(I) Carbonyl Complex
Authors: Rang Maximilian , Fantuzzi Felipe , Arrowsmith Merle , Krummenacher Ivo , Beck Eva , Witte Robert , Matler Alexander , Rempel Anna , Bischof Tobias , Radacki Krzysztof , Engels Bernd , Braunschweig Holger
Published: November 2020

The one‐electron reduction of a cyclic (alkyl)(amino)carbene (CAAC)‐stabilized arylborylene carbonyl complex yields a dimeric borylketyl radical anion, resulting from an intramolecular aryl migration to the CO carbon atom. Computational analyses support the existence of a [(CAAC)B(CO)Ar].− radical anion intermediate. Further reduction leads to a highly nucleophilic dianionic (boraneylidene)methanolate.
Mg‐Pillared LiCoO2: Towards Stable Cycling at 4.6 V
Authors: Huang Yangyang , Zhu Yongcheng , Fu Haoyu , Ou Mingyang , Hu Chenchen , Yu Sijie , Hu Zhiwei , Chen Chien‐Te , Jiang Gang , Gu Hongkai , Lin He , Luo Wei , Huang Yunhui
Published: November 2020

LiCoO2 is used as a cathode material for lithium‐ion batteries, however, cationic/anodic‐redox‐induced unstable phase transitions, oxygen escape, and side reactions with electrolytes always occur when charging LiCoO2 to voltages higher than 4.35 V, resulting in severe capacity fade. Reported here is Mg‐pillared LiCoO2. Dopant Mg ions, serving as pillars in the Li‐slab of LiCoO2, prevent slab sliding in a delithiated state, thereby suppressing unfavorable phase transitions. Moreover, the resulting Li‐Mg mixing structure at the surface of Mg‐pillared LiCoO2 is beneficial for eliminating the cathode‐electrolyte interphase overgrowth and phase transformation in the close‐to‐surface region. Mg‐pillared LiCoO2 exhibits a high capacity of 204 mAh g−1 at 0.2 C and an enhanced capacity retention of 84 % at 1.0 C over 100 cycles within the voltage window of 3.0–4.6 V. In contrast, pristine LiCoO2 has a capacity retention of 14 % within the same voltage window.
Synthesis, characterization, DNA binding/cleavage, cytotoxic, apoptotic, and antibacterial activities of V(IV), Mo(VI), and Ru(II) complexes containing a bioactive ONS‐donor chelating agent
Authors: El‐Afify Marwa E. , Elsayed Shadia A. , Shalaby Thanaa I. , Toson Elshahat A. , El‐Hendawy Ahmed M.
Published: November 2020

New V(IV), Mo(VI), and Ru(II) complexes containing the ligand 2,4‐dihydroxyacetophenone‐S‐methyl dithiocarbazate (H2dhasm); [VO(dhasm)(bpy)] (1) (bpy = 2,2′‐bipyridine), [VO(dhasm)(phen)] (2) (phen = 1,10‐phenanthroline), [MoO2(dhasm)(imz)] (3) (imz = imidazole), [MoO2(dhasm)(DMSO)] (4) (DMSO = dimethylsulfoxide), and [Ru(CO)(PPh3)2(dhasm)] (5) have been synthesized. The ligand and its complexes were structurally characterized by elemental analyses, IR, 1H NMR, EPR, ultraviolet (UV)–visible spectroscopies, magnetic susceptibility, and cyclic voltammetry measurements. Single crystal X‐ray crystallography was used to establish the structure detail of (3) and (4) complexes confirming that the ligand coordinate to the metal ion in a bi‐negative tridentate fashion (dhasm2−, ONS‐donor) in a distorted octahedral geometry. The interaction with calf thymus DNA (CT DNA) of all compounds was studied by UV–visible and fluorescence spectroscopies. Both studies confirmed that these compounds bind to CT DNA through intercalation mode. The DNA cleavage activity of the complexes was also studied on plasmid DNA using gel agarose electrophoresis, and the results revealed that only complexes (2) and (5) have superior cleavage activity in the presence of H2O2. The cytotoxic activity (in vitro) of the complexes on three human cancer cell lines; human liver hepatocellular carcinoma (HepG2), breast adenocarcinoma (MCF7), and epitheliod carcinoma (Hela); and a normal human lung fibroblast (WI‐38) was studied using MTT assay. The complexes exhibited a strong cytotoxicity effect compared with their parent ligand. The ruthenium(II) complex (5) showed the most potent growth inhibition of cancer cells. Also, the mechanism of the apoptotic death in HepG2 cells was studied by observing an increased gene expression of caspase‐3, BAX, P53 and decreased Bcl2 gene expression. The complexes were also screened for their antibacterial activity against gram‐positive and gram‐negative bacteria and showed significant activity against both microorganisms.
Effects of varying melt flow rates on laser melt‐electrospinning of low‐density polyethylene nanofibers
Authors: Zakaria Mohammad , Shibahara Kanta , Bhuiyan Anamul Hoque , Nakane Koji
Published: November 2020

The ultimate functionality and applicability of polymeric nanofibers are mainly to subject on its diameter. This study explores the influence of melt flow rates (MFRs) of low‐density polyethylene (LDPE) on the diameter of laser melt electrospun nanofibers. Ethylene‐vinyl alcohol (EVOH) copolymer was added to the nonpolar LDPE as a spinning aid. After electrospinning, the EVOH was removed from LDPE/EVOH blend fiber by treating with isopropanol/water solution and LDPE nanofiber was obtained with a diameter of only 190 ± 85 nm for the highest MFR. A linear diameter reduction was observed for pure LDPE and EVOH removed LDPE fiber with the increase of MFR. However, a slight diameter increment was reported for the LDPE/EVOH blend fiber with higher MFR due to the improved melt viscosity of the component. A massive diameter decrement was found after EVOH removal from the blended fiber, resulting in the renovation of microfiber to a stable nanoscale dimension.