bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of the Sub-acute Toxicity Profile of Vitex doniana (Sweet) Leaf Fractions on Albino Rats
Authors: Onwukwe O. S. , Ukwuani J. N. , Onyemelukwe A. O. , Azubuike N. C. , Onuba A. C. , Ogu O. C. , Odo O. F. , Achukwu P. U. 
Published: April 2020

Aim: To evaluate the sub-acute toxicity profile of fractions of Vitex doniana using adult albino rats.
Study Design: An experimental study that lasted for 28 days.
Place and Duration of Study: Department of Medical Laboratory Sciences and Animal House Unit, College of Medicine, University of Nigeria Enugu Campus, between January 2019 and March 2019.
Methodology: Methanol, ethyl acetate and hexane fractions of V. doniana were orally administered to 6 groups of animals at doses of 150 mg/kg and 300 mg/kg body weight for each fraction, for 28 days. At the end of the administration, the animals were sacrificed. Body weight changes, Relative Organ Weights (ROW), haematological analysis, serum biochemical assay and histopathological changes of vital organs were used to evaluate the potential toxic effects of the fractions after treatments.
Results: The fractions had no adverse effects on the body weights, ROW and gross appearance of the tissues. There were no significant changes in the haematological and biochemical parameters of the treated animals compared to the controls. Histological assessment of the excised organs also showed no overt pathological changes apart from thickened alveolar septa in the lungs of the animals that received methanol and ethyl acetate fractions.
Conclusion: The polar fractions of V. doniana at the doses tested did not induce any toxic changes in the treated animals.
Screening of Aspergillus and Candida Species with Utmost Potential to Synthesize Citric Acid
Authors: Uzah G. A. , Akani N. P. , Odu N. N. 
Published: April 2020

Background: Citric acid production through fermentation is economical but meeting its increasing global demand has been challenging in recent times.
Aim: This study aimed to screen Aspergillus and Candida sp. isolated from different sources with potentials of producing citric acid.
Methodology: Aspergillus and Candida spp. were isolated from compost soil and fruits (cucumber and banana) and their morphological characteristics were described using standard microbiological methods. The isolates were quantitatively screened for citric acid production based on appearance of yellow zone of clearance for 3 days. All the isolates which had acid unitage (AU) values> 5.0 were selected for further characterization using molecular methods.
Results: Candida tropicalis, Aspergillus sp. A. niger and Penicillium sp. were isolated from the soil and fruit samples. The isolates screened for citric acid production displayed varying diameters of yellow zones around their colonies is indicative of varying capability of the microbial strains. A. niger from compost soil which had highest AU value of 8.5 at Day 3 demonstrated greatest potential to yield citric acid. Molecular characterization revealed high citric acid producing strains as Aspergillus niger (EU440768.1) and Aspergillus welwitschiae (MG669181.1).
Conclusion: Although Aspergillus niger is widely utilized for industrial production of citric acid, this study has demonstrated that A. welwitschiae is a specie of Aspergillus capable of synthesizing citric acid reasonably.
Technology‐Integrated Project‐Based Language Learning
Authors: Beckett Gulbahar H. , Slater Tammy 
Published: April 2020

Abstract
This entry defines project‐based language learning (PBLL) as a student‐centered, comprehensive approach that focuses on the development of language, content, and skills in an integrated and meaningful way. It also focuses on research that utilizes technology in its implementation. It lists criteria involved in the approach, provides a review of the findings from research on technology‐mediated PBLL, and identifies gaps for further research.
Textbook Analysis
Authors: Weninger Csilla 
Published: April 2020

AbstractTextbook analysis is a small but distinct subfield of applied linguistic research aimed at examining textbooks as curricular‐cultural artifacts that communicate important meanings through their content and design. Orienting to an interdisciplinary, critical theoretical paradigm, researchers examine how the textual and visual material in textbooks represents people, places, and languages as well as how it positions and shapes learners' understanding.
Concentration‐Driven Disruption of Single‐File Water
Authors: Rezvova Maria , Gölzhäuser Armin , Dementyev Petr 
Published: April 2020

AbstractStrong hydrogen bonding is known to entail some of the spectacular physical properties of liquid water, including fast diffusion under nanoconfinement. Similar to biological channels, the single‐file or collective motion of interconnected water molecules has been observed in nanotubes and laminar structures, exhibiting tremendous potential for energy‐efficient separation applications. Desalination, breaking azeotropes, and dehumidification have been all addressed with the membranes enabling selective transport of water while most attention has been paid to the fabrication and morphological characteristics of the respective microporous materials. However, the performance of membrane processes also depends on the properties of the chemical systems to be treated, often facing problems under realistic conditions such as concentration polarization. In this study, adsorption controlled permeation is employed to explore the interfacial behavior of water–alcohol mixtures in nanostructured membranes as a function of concentration. The permeation rate of water is found to sink manifold as the molar fraction of isopropanol molecules increases, indicating breakdown of the single‐file mechanism. A phenomenological model is devised to account for intermolecular interactions in the binary liquid–liquid mixture whereas kinetic simulations agree well with the experimental data. The results point to the fundamental limitations of water‐selective conduits for dehydrating organic solvents.
Key Ionic Electrolytes for Highly Self‐Stable Light‐Emitting Electrochemical Cells Based on Ir(III) Complexes
Authors: Fresta Elisa , Monclús Miguel A. , Bertz Morten , Ezquerro Cintia , Molina‐Aldareguia Jon M. , Berenguer Jesús R. , Kunimoto Masahiro , Homma Takayuki , Costa Rubén D. 
Published: April 2020

AbstractSelf‐stability in light‐emitting electrochemical cells (LECs) based on Ir(III) ionic transition metal complexes (Ir‐iTMC) has been long overlooked. Herein, it is demonstrated that the nature of the active layer blending an archetype Ir‐iTMC as emitter and ionic electrolytes—ionic liquid (IL) or ionic polyelectrolyte (IP)—is paramount for the storage and mechanical stability of rigid/flexible LECs. Strikingly, devices with ionic polyelectrolytes (IPs) stand out compared to those with traditional configurations with or without ILs. They exhibit i) superior brightness and efficiencies in rigid/flexible devices due to the higher photoluminescence quantum yield, ii) the best performance at pulsed current driving mode under inert/ambient operation conditions due to a slower growth of the doped regions, iii) enhanced device stabilities upon ambient/inert storage, resulting in <10% performance loss after 1 month of aging, and iv) the smallest performance loss (<10%) upon bending stress, since IPs prevent mechanically induced damage, preserving morphological and spectroscopic features. These findings are supported by steady‐state and time‐resolved emission spectroscopy, electrochemical impedance spectroscopy, microscopic and mechanical assays, along with the analysis of fresh and aged devices driven at different modes under inert/ambient conditions. Overall, this work highlights the need of revisiting new emitter:electrolyte combinations toward realizing highly self‐stable LECs.
Insights into the Substrate Promiscuity of Novel Hydroxysteroid Dehydrogenases
Authors: Bertuletti Susanna , Ferrandi Erica Elisa , Marzorati Stefano , Vanoni Marta , Riva Sergio , Monti Daniela 
Published: April 2020

AbstractHydroxysteroid dehydrogenases (HSDHs) are valuable biocatalysts for the regio‐ and stereoselective modification of steroids, bile acids and other steroid derivatives. In this work, we investigated the substrate promiscuity of this highly selective class of enzymes. In order to reach this goal, a preliminary search of HSDH homologues in in‐house or public available (meta)genomes was carried out. Eight novel NAD(H)‐dependent HSDHs, showing either 7α‐, 7β‐, or 12α‐HSDH activity, and including, for the first time, enzymes from extremophilic microorganisms, were identified, recombinantly produced, and characterized. Among the novel HSDHs, four highly active (up to 92 U mg−1) NAD(H)‐dependent 7β‐HSDHs showing negligible similarity towards previously described 7β‐HSDHs, were discovered.These enzymes, along with previously characterized HSDHs, were tested as biocatalysts for the stereoselective reduction of a panel of substrates including two α‐ketoesters of pharmaceutical interest and selected ketones that partially resemble the structural features of steroids. All the reactions were coupled with a suitable cofactor regeneration system. Regarding the α‐ketoesters, nearly all of the tested HSDHs showed a good activity toward the selected substrates, yielding the reduced α‐hydroxyester with up to 99% conversions and enantiomeric excesses. On the other hand, only the 7β‐HSDHs from Collinsella aerofaciens and Clostridium absonum showed appreciable activity toward more complex ketones, i. e., (±)‐trans‐1‐decalone, but with interesting as well as different selectivity.magnified image
Constructing High‐Performance Organic Photovoltaics via Emerging Non‐Fullerene Acceptors and Tandem‐Junction Structure
Authors: Cheng Pei , Wang Jiayu , Zhan Xiaowei , Yang Yang 
Published: April 2020

AbstractIn consideration of the unique advantages of new non‐fullerene acceptors and the tandem‐junction structure, organic photovoltaics (OPVs) based on them are very promising. Studies related to this emerging area began in 2016 with achieved power conversion efficiencies (PCEs) of 8–10%, which have now been boosted to 17%. In this essay, the construction of high‐performance OPVs is discussed, with a focus on combining the advantages of new non‐fullerene acceptors and the tandem‐junction structure. In order to achieve higher PCEs, methods to enable high short‐circuit current density, open‐circuit voltage, and fill factor are discussed. In addition, the stability and reproducibility of high‐efficiency OPVs are also addressed. Herein, it is forecast that the new non‐fullerene acceptors‐based tandem‐junction OPVs will become the next big wave in the field and achieve high PCEs over 20% in the near future. Some promising research directions on this emerging hot topic are proposed which may further push the field into the 25% high efficiency era and considerably advance the technology beyond laboratory research.
Alternative assays to dRVVT and aPTT for lupus anticoagulant detection
Authors: Moore Gary W. 
Published: April 2020

AbstractLupus anticoagulants (LA) are heterogeneous antibodies and no single assay will detect every LA. Consequently, testing is commonly undertaken with both dilute Russell's viper venom time (dRVVT) and LA‐responsive activated partial thromboplastin time (aPTT) to maximize detection rates. Although a huge body of evidence attests to the diagnostic utility of these assays, they have limitations that can render them unreliable in certain circumstances. Other assays are available for detecting LA but unfamiliarity, variable availability and technical concerns expressed in guidelines contribute to less usage than dRVVT and aPTT. However, assays such as Taipan snake venom time and Textarin time are insensitive to anticoagulants that compromise dRVVT and aPTT, and assays such as dilute prothrombin time can detect LA unreactive in dRVVT and aPTT. The pros and cons of alternative assays to dRVVT and APTT for LA detection are discussed.
An Autonomous Chemical Robot Discovers the Rules of Inorganic Coordination Chemistry without Prior Knowledge
Authors: Porwol Luzian , Kowalski Daniel J. , Henson Alon , Long De‐Liang , Bell Nicola L. , Cronin Leroy 
Published: April 2020

AbstractWe present a chemical discovery robot for the efficient and reliable discovery of supramolecular architectures through the exploration of a huge reaction space exceeding ten billion combinations. The system was designed to search for areas of reactivity found through autonomous selection of the reagent types, amounts, and reaction conditions aiming for combinations that are reactive. The process consists of two parts where reagents are mixed together, choosing from one type of aldehyde, one amine and one azide (from a possible family of two amines, two aldehydes and four azides) with different volumes, ratios, reaction times, and temperatures, whereby the reagents are passed through a copper coil reactor. Next, either cobalt or iron is added, again from a large number of possible quantities. The reactivity was determined by evaluating differences in pH, UV‐Vis, and mass spectra before and after the search was started. The algorithm was focused on the exploration of interesting regions, as defined by the outputs from the sensors, and this led to the discovery of a range of 1‐benzyl‐(1,2,3‐triazol‐4‐yl)‐N‐alkyl‐(2‐pyridinemethanimine) ligands and new complexes: [Fe(L1)2](ClO4)2 (1); [Fe(L2)2](ClO4)2 (2); [Co2(L3)2](ClO4)4 (3); [Fe2(L3)2](ClO4)4 (4), which were crystallised and their structure confirmed by single‐crystal X‐ray diffraction determination, as well as a range of new supramolecular clusters discovered in solution using high‐resolution mass spectrometry.
Chalcogen Bond Mediated Enhancement of Cooperative Ion‐Pair Recognition
Authors: Bunchuay Thanthapatra , Docker Andrew , Eiamprasert Utt , Surawatanawong Panida , Brown Asha , Beer Paul D. 
Published: April 2020

AbstractA series of heteroditopic receptors containing halogen bond (XB) and unprecedented chalcogen bond (ChB) donors integrated into a 3,5‐bis‐triazole pyridine structure covalently linked to benzo‐15‐crown‐5 ether motifs exhibit remarkable cooperative recognition of halide anions. Multi‐nuclear 1H, 13C, 125Te and 19F NMR, ion pair binding investigations reveal sodium cation–benzo‐crown ether binding dramatically enhances the recognition of bromide and iodide halide anions, with the chalcogen bonding heteroditopic receptor notably displaying the largest enhancement of halide binding strength of over two hundred‐fold, in comparison to the halogen bonding and hydrogen bonding heteroditopic receptor analogues. DFT calculations suggest crown ether sodium cation complexation induces a polarisation of the sigma hole of ChB and XB heteroditopic receptor donors as a significant contribution to the origin of the unique cooperativity exhibited by these systems.
Semisynthesis of Functional Glycosylphosphatidylinositol‐Anchored Proteins
Authors: Roller Renée F. , Malik Ankita , Carillo Maria A. , Garg Monika , Rella Antonella , Raulf Marie‐Kristin , Lepenies Bernd , Seeberger Peter H. , Varón Silva Daniel 
Published: April 2020

AbstractGlypiation is a common posttranslational modification of eukaryotic proteins involving the attachment of a glycosylphosphatidylinositol (GPI) glycolipid. GPIs contain a conserved phosphoglycan that is modified in a cell‐ and tissue‐specific manner. GPI complexity suggests roles in biological processes and effects on the attached protein, but the difficulties to get homogeneous material have hindered studies. We disclose a one‐pot intein‐mediated ligation (OPL) to obtain GPI‐anchored proteins. The strategy enables the glypiation of folded and denatured proteins with a natural linkage to the glycolipid. Using the strategy, glypiated eGFP, Thy1, and the Plasmodium berghei protein MSP119 were prepared. Glypiation did not alter the structure of eGFP and MSP119 proteins in solution, but it induced a strong pro‐inflammatory response in vitro. The strategy provides access to glypiated proteins to elucidate the activity of this modification and for use as vaccine candidates against parasitic infections.
Observation of the Low‐Frequency Spectrum of the Water Trimer as a Sensitive Test of the Water‐Trimer Potential and the Dipole‐Moment Surface
Authors: Schwan Raffael , Qu Chen , Mani Devendra , Pal Nitish , Schwaab Gerhard , Bowman Joel M. , Tschumper Gregory S. , Havenith Martina 
Published: April 2020

AbstractIntermolecular interactions in bulk water are dominated by pairwise and non‐pairwise cooperative interactions. While accurate descriptions of the pairwise interactions are available and can be tested by precise low‐frequency spectra of the water dimer up to 550 cm−1, the same does not hold for the three‐body interactions. Here, we report the first comprehensive spectrum of the water trimer in the frequency region from 70 to 620 cm−1 using helium‐nanodroplet isolation and free‐electron lasers. By comparison to accompanying high‐level quantum calculations, the experimentally observed intermolecular bands can be assigned. The transition frequencies of the degenerate translation, the degenerate in‐plane and the non‐degenerate out‐of‐plane libration, as well as additional bands of the out‐of‐plane librational mode are reported for the first time. These provide a benchmark for state‐of‐the‐art water potentials and dipole‐moment surfaces, especially with respect to three‐body interactions.
In Situ Synthesis of an Aptamer‐Based Polyvalent Antibody Mimic on the Cell Surface for Enhanced Interactions between Immune and Cancer Cells
Authors: Shi Peng , Wang Xuelin , Davis Brandon , Coyne James , Dong Cheng , Reynolds Joshua , Wang Yong 
Published: April 2020

AbstractAn ability to promote therapeutic immune cells to recognize cancer cells is important for the success of cell‐based cancer immunotherapy. We present a synthetic method for functionalizing the surface of natural killer (NK) cells with a supramolecular aptamer‐based polyvalent antibody mimic (PAM). The PAM is synthesized on the cell surface through nucleic acid assembly and hybridization. The data show that PAM has superiority over its monovalent counterpart in powering NKs to bind to cancer cells, and that PAM‐engineered NK cells exhibit the capability of killing cancer cells more effectively. Notably, aptamers can, in principle, be discovered against any cell receptors; moreover, the aptamers can be replaced by any other ligands when developing a PAM. Thus, this work has successfully demonstrated a technology platform for promoting interactions between immune and cancer cells.
Reduktive Desaminierung mit Hydrosilanen katalysiert durch B(C6F5)3
Authors: Fang Huaquan , Oestreich Martin 
Published: April 2020

AbstractEs ist bekannt, dass die starke Bor‐Lewis‐Säure Tris(pentafluorphenyl)boran B(C6F5)3 die dehydrierende Kupplung von bestimmten Aminen und Hydrosilanen bei erhöhten Temperaturen katalysiert. Bei noch höheren Temperaturen konkurriert der Reaktionspfad der Dehydrierung mit dem Bruch der C‐N‐Bindung, was in Defunktionalisierung mündet. Genau das lässt sich zu einer nützlichen Methode für die übergangsmetallfreie, reduktive Desaminierung einer breiten Palette an Aminen sowie Heterocumulenen, z. B. einem Isocyanat und einem Isothiocyanat, ausbauen.
Ultrathin polypyrrole films on self‐assembled monolayers as an efficient ultramicroelectrode assay
Authors: Bolat Gulcin , Yaman Yesim T. , Kuralay Filiz , Abaci Serdar 
Published: April 2020

AbstractIn this work, we investigated the effect of electrodeposition of polypyrrole (PPy) films on two different self‐assembled monolayers (SAMs) modified gold electrode for the electrochemical construction of ultramicroelectrode (UME). In order to obtain SAM modified surfaces, 4‐mercapto‐1‐butanol and 11‐mercaptoundecanoic acid were used. The effect of these two chains on pyrrole electropolymerization was compared. Electropolymerization of pyrrole on SAM modified Au electrode was carried out by using cyclic voltammetry (CV) and constant potential electrolysis. To investigate the UME formation, the obtained surfaces were tested in Fe(CN)63−/4− redox system. UMEs were characterized using scanning electron microscopy energy‐dispersive X‐ray spectroscopy, attenuated total reflectance fourier transform infrared spectroscopy and electrochemical impedance spectroscopy. The designed UME was applied as an immobilization matrix to entrap a redox protein, Hemoglobin (Hb), as a model. Direct electron transfer between this protein and the fabricated thiol modified PPy based UME was achieved, which is very challenging on bare electrode surfaces. With this study, a simple, low‐cost and reproducible UME production way has been successfully accomplished and Hb modified UME is promising for different bioanalytical applications, for instance; cellular hydrogen peroxide or nitrite sensing.
Impurity profiling high‐performance‐thin‐layer chromatography method involving the assay of essential human micronutrient niacin with eco‐scale assessment
Authors: Naguib Ibrahim A. , Draz Mohammed E. , Abdallah Fatma F. 
Published: April 2020

AbstractCurrently, analytical scientists are paying special attention to reducing reliance on hazardous chemicals in various analytical methods. By embracing this concept, we developed an eco‐friendly high‐performancethin‐layer chromatography (HPTLC) method as an alternative for the conventional HPLC method for the determination of an essential human micronutrient, niacin (NIA), which is used improve the lipid profile of patients. Furthermore, the proposed HPTLC method is capable of determining the structurally related impurities of NIA such as pyridine‐2,5‐dicarboxylic acid, isonicotinic acid, pyridine, and 5‐ethyl‐2‐methylpyridine, which exhibit nephrotoxic and hepatotoxic effects. The separation of this challenging mixture was achieved on HPTLC sheets using a mixture of ethyl acetate/ethanol/ammonia solution (6:4:0.05, v/v/v), and then the dried plates were scanned at 254 nm. The analytical eco‐scale assessment protocol was used to assess the greenness profile of the presented method and compare it with the reported HPLC method. The suggested method was found to be greener with regard to the consumption of solvents and the yielding of waste. The results suggest that the described method can be safely implemented for the routine analysis of NIA pharmaceutical dosage without the interference of potential impurities in quality control laboratories.