bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design, Synthesis, Antimicrobial and Antioxidant Activities of Novel Threonine-based Sulfonamide Derivatives
Authors: Egbujor M. C. , Okoro U. C. , Nwobodo D. C. , Ezeagu C. U. , Amadi U. B. , Okenwa-Ani C. G. , Ugwu J. I. , Okoye I. G. , Abu I. P. , Egwuatu P. I. 
Published: June 2020

Aim: To systematically design, synthesize and evaluate the biological activities of new threonine-based sulfonamide derivatives in order to achieve improved drug potency.
Methodology: Sulfamoyl carboxylic acids were prepared by the reaction of threonine with the appropriate sulfonyl chloride while their acetylated, carboxamide and aniline derivatives were synthesized via Lumiere-Barbier acetylation, Schotten-Baumann ammonolysis and Buchwald-Hartwig cross-coupling methods respectively. The FTIR, 1H-NMR, 13C-NMR and elemental analytical data were employed in the structural characterization. In vitro and in silico antioxidant and antimicrobial studies were carried out.
Results: Compounds 1b and 1d displayed the best in vitro antibacterial activities against Escherichia coli, Salmonella typhi, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and antifungal activities against Candida albican sand Aspergillus niger. Compound 1f (IC50 = 1.150±0.003 µg/ml) exhibited the best in vitro antioxidant activity. Compound 1a had a higherin silico antibacterial (-11.51 kcal/mol) binding energies than antibacterial reference drug, penicillin (-10.89 kcal/mol). Compound 1c had the highest in silico antifungal binding energy (-10.48 kcal/mol)comparable to ketoconazole (-10.85 kcal/mol).
Conclusion: All the compounds were found to be potential antioxidant and antimicrobial drug candidates having complied with Lipinski’s rule of five.
The STAT3‐miR‐223‐TGFBR3/HMGCS1 axis modulates the progression of cervical carcinoma
Authors: Zhang Ju , Jiang Ming , Qian Lili , Lin Xiao , Song Weiguo , Gao Yunfeng , Zhou Ying 
Published: June 2020

Cervical cancer is induced by persistent infections with high‐risk human papillomaviruses (HPVs), which produce the early protein 6 of HPVs (E6)/E7 protein that is involved in cell transformation by interacting with several oncoproteins or tumor suppressors. However, the role of noncoding RNA in mediating the pathogenesis of cervical cancer remains unclear. Here, we report that the novel signal transducer and activator of transcription 3 (STAT3)‐microRNA‐223‐3p (miR‐223)‐TGFBR3/HMGCS1 axis regulated by the E6 protein controls cervical carcinogenesis. miR‐223 was highly expressed in cervical tumor tissues, whereas TGFBR3 or HMGCS1 was significantly downregulated. miR‐223 targeted the 3′‐UTRs of TGFBR3 and HMGCS1 and suppressed their expression, leading to increased anchorage‐independent growth and cervical squamous cell carcinoma (CSCC) tumor growth in vitro and in vivo. The increased expression of miR‐223 was mediated by the transcription factor STAT3, whose activity was enhanced by E6 in the context of interleukin (IL)‐6 stimulation. In addition, exosomal miR‐223 derived from CSCC cells induced IL‐6 secretion by monocyte/macrophage in a coculture system in vitro, and IL‐6 secretion, in turn, led to enhanced STAT3 activity in CSSC cells, forming a positive feedback loop. Furthermore, modified miR‐223 inhibitor effectively suppressed tumor growth in cell line‐derived xenograft model, suggesting that miR‐223 is a potential promising therapeutic target in CSCC. In conclusion, our results demonstrate that the STAT3‐miR‐223‐HMGCS1/TGFBR3 axis functions as a key signaling pathway in cervical cancer progression and provides a new therapeutic target.
Evaluating the positional uncertainty of intrafraction, adjacent fields, and daily setup with the BrainLAB ExacTrac system in patients who are receiving craniospinal irradiation
Authors: Duan Xiaojuan , Zhou Yibing , Dai Hongya , Zhao Lirong , Qian Jindong , Yang Dingqiang , Zhang Liwei , Luo Can , Li Guanghui 
Published: June 2020

AbstractPurposeTo investigate the daily setup, interfraction motion, variability in the junction areas, and dosimetric effect in craniospinal irradiation (CSI) patients.MethodsFifteen CSI patients who had undergone split‐field IMRT were followed in the study. Previous, middle, and posttreatment, each target volume position was evaluated using the ExacTrac system. Interfraction and intrafraction motions, the margin of the junction in adjacent targets volumes, and the dosimetric effect of the longitudinal residual error were analyzed.ResultsThe lowest attainment rate within the tolerance of the initial setup error was 66.79% in six directions. The values of the initial error were within 15 mm (SD 4.5 mm) in the translation direction and 5° (SD 1.3°) in the rotation direction after the transposition of the treatment isocenter. With the guidance of the ExacTrac system, the interfraction and intrafraction residual errors were almost within the tolerance after correction, the margin of CTV‐to‐PCTV was in the range of target expansion criteria. The residual longitudinal errors resulted in only slight changes in the mean doses of PGTV and PCTV, while the maximum dose of the spinal cord increased by 16.1%. The patients did not exhibit any side‐effects by the overall treatment during the follow‐up period.ConclusionsPosition correction is necessary after setup and the transposition of the treatment isocenter. Intra‐fraction motion in the lateral direction should be monitored throughout treatment. The position errors in junction areas are almost within the tolerance after correction. The patients did not exhibit any side‐effects by the overall treatment.
Silica Nanostructures Produced Using Diatom Peptides with Designed Post‐Translational Modifications
Authors: Wallace Andrea K. , Chanut Nicolas , Voigt Christopher A. 
Published: June 2020

AbstractDiatoms produce intricately patterned silica structures under ambient conditions, a process initiated by post‐translationally modified silaffin peptides that nucleate silicic acid. Designing these peptides would enable the production of silica nanostructures with desired properties; however, the functional effects of modifications are poorly understood. Here, Escherichia coli is used to express and modify recombinant silaffin R5 peptide from the diatom Cylindrotheca fusiformis. A library of 38 enzymes is tested for R5 modifications in vitro, from which active methyltransferases, kinases, acetyltransferases, oxidases, and myristoyltransferases are identified from diatoms, humans, yeast, and bacteria. Modified R5 peptides are used for silica precipitation and the impacts on particle size, shape, porosity, and surface area are quantified. In vivo pathways are designed to coexpress R5 and a modifying enzyme and the resulting peptide is used to nucleate silica nanostructures with controlled size (100–3500 nm), porosity (20–635 m2 g−1), or embedded with melanin. It is found that phosphorylation reduces the need for inorganic phosphate during silica synthesis. The simultaneous methylation and phosphorylation of R5 leads to smaller particles requiring less inorganic phosphate. Inspired by diatoms, the use of post‐translationally modified peptides will enable the control of silica morphology under ambient conditions, with potential applications in electronics and photonics.
Synthesis of Two‐Dimensional Perovskite by Inverse Temperature Crystallization and Studies of Exciton States by Two‐Photon Excitation Spectroscopy
Authors: Chen Zhihui , Zhang Qi , Zhu Menglong , Wang Xinyun , Wang Qixing , Wee Andrew Thye Shen , Loh Kian Ping , Eda Goki , Xu Qing‐Hua 
Published: June 2020

AbstractTwo‐dimensional (2D) organic–inorganic hybrid perovskites (OIHPs), a natural multiple‐quantum‐well structure with quasi‐2D electronic properties, have recently emerged as a promising class of semiconducting materials for photovoltaic and optoelectronic applications. However, facile synthesis of high‐quality 2D OIHPs single crystals is still lacking. The layer dependence of the exciton binding energy of (C4H9NH3)2PbI4 (C4PI), a widely studied 2D OIHP, is still debated. Herein, a novel synthesis technique based on inverse temperature crystallization in a binary‐solvent system is used to prepare 2D OIHPs and a systematic study of excitonic states of the synthesized 2D OIHPs by two‐photon excitation (TPE) spectroscopy is conducted. The obtained TPE spectra indicate that the exciton binding energies are similar for C4PI nanosheets and bulk crystals with different number of layers, most likely due to the intrinsically weak interlayer coupling. Further, the dark excitonic 2p states of (C6H5(CH2)2NH3)2PbI4 (PEPI) and C4PI are also observed by TPE spectroscopy. The results provide a novel synthesis protocol and insight into exciton properties of 2D OIHPs.
Ammonia Thermal Treatment toward Topological Defects in Porous Carbon for Enhanced Carbon Dioxide Electroreduction
Authors: Dong Yan , Zhang Qiuju , Tian Ziqi , Li Boran , Yan Wensheng , Wang Shuo , Jiang Kemin , Su Jianwei , Oloman Colin W. , Gyenge Elod L. , Ge Ruixiang , Lu Zhiyi , Ji Xiulei , Chen Liang 
Published: June 2020

AbstractTopological defects, with an asymmetric local electronic redistribution, are expected to locally tune the intrinsic catalytic activity of carbon materials. However, it is still challenging to deliberately create high‐density homogeneous topological defects in carbon networks due to the high formation energy. Toward this end, an efficient NH3 thermal‐treatment strategy is presented for thoroughly removing pyrrolic‐N and pyridinic‐N dopants from N‐enriched porous carbon particles, to create high‐density topological defects. The resultant topological defects are systematically investigated by near‐edge X‐ray absorption fine structure measurements and local density of states analysis, and the defect formation mechanism is revealed by reactive molecular dynamics simulations. Notably, the as‐prepared porous carbon materials possess an enhanced electrocatalytic CO2 reduction performance, yielding a current density of 2.84 mA cm−2 with Faradaic efficiency of 95.2% for CO generation. Such a result is among the best performances reported for metal‐free CO2 reduction electrocatalysts. Density functional theory calculations suggest that the edge pentagonal sites are the dominating active centers with the lowest free energy (ΔG) for CO2 reduction. This work not only presents deep insights for the defect engineering of carbon‐based materials but also improves the understanding of electrocatalytic CO2 reduction on carbon defects.
Low‐Loss Organic Hyperbolic Materials in the Visible Spectral Range: A Joint Experimental and First‐Principles Study
Authors: Lee Yeon Ui , Yim Kanghoon , Bopp Steven Edward , Zhao Junxiang , Liu Zhaowei 
Published: June 2020

AbstractHyperbolic media strengthen numerous attractive applications in optics such as super‐resolution imaging, enhanced spontaneous emission, and nanoscale waveguiding. Natural hyperbolic materials exist at visible frequencies; however, implementations of these materials suffer substantial compromises resulting from the high loss in the currently available candidates. Here, the first experimental and theoretical investigation of regioregular poly(3‐alkylthiophenes) (rr‐P3ATs), a naturally low‐loss organic hyperbolic material (OHM) in the visible frequency range, is shown. These hyperbolic properties arise from a highly ordered structure of layered electron‐rich conjugated thiophene ring backbones separated by insulating alkyl side chains. The optical and electronic properties of the rr‐P3AT can be tuned by controlling the degree of crystallinity and alkyl side chain length. First‐principles calculations support the experimental observations, which result from the rr‐P3AT's structural and optical anisotropy. Conveniently, rr‐P3AT‐based OHMs are facile to fabricate, flexible, and biocompatible, which may lead to tremendous new opportunities in a wide range of applications.
Charge State Control of F16CoPc on h‐BN/Cu(111)
Authors: Pörtner Mathias , Wei Yinying , Riss Alexander , Seufert Knud , Garnica Manuela , Barth Johannes V. , Seitsonen Ari P. , Diekhöner Lars , Auwärter Willi 
Published: June 2020

AbstractThe use of molecular materials in solar cells and nano‐electronics demands a fundamental understanding and control of their electronic properties. Particularly relevant is the molecular response to the environment, that is, the interaction with the support and adjacent molecules, as well as the influence of electrostatic gating. Here, the control of molecular level alignment and charge states of fluorinated cobalt phthalocyanines (F16CoPc) on atomically thin hexagonal boron nitride (h‐BN) sheets on Cu(111) is reported using scanning tunneling microscopy (STM) and spectroscopy (STS), as well as atomic force microscopy (AFM) and complementary density functional theory (DFT) calculations. Three parameters that govern the electronic level alignment of F16CoPc orbitals are investigated: i) template‐induced gating by the work function variation of the h‐BN/Cu(111) substrate, ii) gating by the STM tip, and iii) screening by neighboring molecules. The interplay of these parameters influences the charge distribution in the studied molecular arrangements and thus provides the possibility to tune their physicochemical behavior, for instance, the response toward electronic or optical excitation, charge transport, or binding of axial adducts.
Tunable Resonance and Phase Vortices in Kirigami Fano‐Resonant Metamaterials
Authors: Jeong Hoon Yeub , Lim Yeonsoo , An Soo‐Chan , Nguyen Thi Hai‐Yen , Byun Gangil , Jun Young Chul 
Published: June 2020

AbstractEmerging internet‐of‐things technologies require widespread antennas and sensors. They should be cheap enough to be widely deployed, but still should be highly functional and tunable. Here, a thorough, in‐depth study of spectral shifts and phase vortices in kirigami Fano‐resonant metamaterials is presented. Microwave metamaterials are printed on paper using metal inks. Then, the printed metamaterials are cut line‐by‐line and folded, so that a step height between neighboring unit cells can be created. By varying step heights, significant spectral tuning as well as resonance switching are obtained. The large spectral shift of the highly asymmetric Fano lineshape also enables significant control of radiation direction. The observations are explained based on the interactions between neighboring unit cells. Moreover, phase singularities are found at the zero‐amplitude position of the Fano resonance spectrum, and a pair of phase vortices appear in parameter space. The kirigami metamaterials allow an easy parameter scan, and therefore significant control of the spectral phase becomes possible. Such drastic phase changes around singularity points could be very useful for various applications, including optical sensing and wavefront manipulation. The kirigami metamaterials enable easily fabricated but highly functional and tunable elements, which could be useful for various antennas and sensors.
Characteristic dental pattern with hypodontia and short roots in Fraser syndrome
Authors: Kunz Felix , Kayserili Hülya , Midro Alina , de Silva Deepthi , Basnayake Sriyani , Güven Yeliz , Borys Jan , Schanze Denny , Stellzig‐Eisenhauer Angelika , Bloch‐Zupan Agnes , Zenker Martin 
Published: June 2020

AbstractFraser syndrome (FS) is a rare autosomal recessive multiple congenital malformation syndrome characterized by cryptophthalmos, cutaneous syndactyly, renal agenesis, ambiguous genitalia, and laryngotracheal anomalies. It is caused by biallelic mutations of FRAS1, FREM2, and GRIP1 genes, encoding components of a protein complex that mediates embryonic epithelial–mesenchymal interactions. Anecdotal reports have described abnormal orodental findings in FS, but no study has as yet addressed the orodental findings of FS systematically. We reviewed dental radiographs of 10 unrelated patients with FS of different genetic etiologies. Dental anomalies were present in all patients with FS and included hypodontia, dental crowding, medial diastema, and retained teeth. A very consistent pattern of shortened dental roots of most permanent teeth as well as altered length/width ratio with shortened dental crowns of upper incisors was also identified. These findings suggest that the FRAS1–FREM complex mediates critical mesenchymal–epithelial interactions during dental crown and root development. The orodental findings of FS reported herein represent a previously underestimated manifestation of the disorder with significant impact on orodental health for affected individuals. Integration of dentists and orthodontists into the multidisciplinary team for management of FS is therefore recommended.
Association of diabetes with stroke and post‐stroke dementia: A population‐based cohort study
Authors: Shang Ying , Fratiglioni Laura , Marseglia Anna , Plym Anna , Welmer Anna‐Karin , Wang Hui‐Xin , Wang Rui , Xu Weili 
Published: June 2020

AbstractIntroductionThe impact of prediabetes and diabetes on stroke and the development of dementia after a stroke remain unclear.MethodsA total of 2655 dementia‐free participants (including a stroke‐free cohort and a prevalent stroke cohort) were followed‐up for 12 years. Dementia and post‐stroke dementia were determined by clinical examinations and national registry data. Diabetes was ascertained via medical examination, medication use, medical records, or glycated hemoglobin (HbA1c) ≥6.5%. Prediabetes was defined as HbA1c ≥5.7% in diabetes‐free participants.ResultsIn the stroke‐free cohort, 236 participants developed ischemic stroke, and 47 developed post‐stroke dementia. Diabetes was associated with ischemic stroke (hazard ratio [HR] 1.76, 95% confidence interval [CI] 1.16 to 2.67) and post‐stroke dementia (HR 2.56, 95% CI 1.04 to 6.25). In the prevalent stroke cohort, diabetes was also related to dementia risk. Prediabetes was not significantly related to stroke or post‐stroke dementia.DiscussionDiabetes, but not prediabetes, is associated with an increased risk of ischemic stroke and post‐stroke dementia.
Design of Bowl‐Shaped N‐Hydroxyimide Derivatives as New Organoradical Catalysts for Site‐Selective C(sp3)−H Bond Functionalization Reactions
Authors: Kato Terumasa , Maruoka Keiji 
Published: June 2020

AbstractA series of new bowl‐shaped N‐hydroxyimide derivatives has been designed and used as selective organoradical catalysts. A number of these bowl‐shaped N‐hydroxyimide derivatives exhibit excellent site‐selectivity in the amination of benzylic C(sp3)−H bonds in aromatic hydrocarbon substrates.
Kristallstruktur und Spektroskopie offenbaren einen Schwefel‐Liganden am aktiven Zentrum einer O2‐stabilen [FeFe]‐Hydrogenase
Authors: Rodríguez‐Maciá Patricia , Galle Lisa M. , Bjornsson Ragnar , Lorent Christian , Zebger Ingo , Yoda Yoshitaka , Cramer Stephen P. , DeBeer Serena , Span Ingrid , Birrell James A. 
Published: June 2020

Abstract[FeFe]‐Hydrogenasen sind die aktivsten natürlich vorkommenden Katalysatoren zur Wasserstofferzeugung. Ihre technologische Anwendung ist jedoch durch ihre extreme Sauerstoffempfindlichkeit begrenzt. Aus sulfatreduzierenden Bakterien können sie aber in dem sauerstoffstabilen Hinact‐Zustand isoliert werden. Die Struktur dieses Enzyms, sowie der Bildungsmechanismus dieses Zustands sind jedoch bis heute unbekannt. Unsere Kristallstruktur solch einer [FeFe]‐Hydrogenase im Hinact‐Zustand mit einer Auflösung von 1.65 Å zeigt, dass ein Schwefelligand die freie Koordinationsstelle besetzt. Durch kernresonante inelastische Streuung, Resonanz‐ Raman‐, Infrarot‐ und Röntgenabsorptionsspektroskopie, jeweils in Kombination mit Hybrid‐quantenmechanischen/molekülmechanischen (QM/MM) Berechnungen, konnten wir detaillierte Informationen zu Struktur und Bildung des Hinact‐Zustands erhalten. Diese Erkenntnisse könnten zur Entwicklung sauerstoffstabiler Hydrogenasen und molekularer Katalysatoren beitragen.
Compressing Double [7]Helicene by Successive Charging with Electrons
Authors: Zhou Zheng , Fu Lin , Hu Yunbin , Wang Xiao‐Ye , Wei Zheng , Narita Akimutsu , Müllen Klaus , Petrukhina Marina A. 
Published: June 2020

AbstractChemical reduction of a benzo‐fused double [7]helicene (1) with two alkali metals, K and Rb, provided access to three different reduced states of 1. The doubly‐reduced helicene 12− has been characterized by single‐crystal X‐ray diffraction as a solvent‐separated ion triplet with two potassium counterions. The triply‐ and tetra‐reduced helicenes, 13− and 14−, have been crystallized together in an equimolar ratio and both form the contact‐ion complexes with two Rb+ ions each, leaving three remaining Rb+ ions wrapped by crown ether and THF molecules. As structural consequence of the stepwise reduction of 1, the central axis of helicene becomes more compressed upon electron addition (1.42 Å in 14− vs. 2.09 Å in 1). This is accompanied by an extra core twist, as the peripheral dihedral angle increases from 16.5° in 1 to 20.7° in 14−. Theoretical calculations provided the pattern of negative charge build‐up and distribution over the contorted helicene framework upon each electron addition, and the results are consistent with the X‐ray crystallographic and NMR spectroscopic data.
Caught in the Hinact: Crystal Structure and Spectroscopy Reveal a Sulfur Bound to the Active Site of an O2‐stable State of [FeFe] Hydrogenase
Authors: Rodríguez‐Maciá Patricia , Galle Lisa M. , Bjornsson Ragnar , Lorent Christian , Zebger Ingo , Yoda Yoshitaka , Cramer Stephen P. , DeBeer Serena , Span Ingrid , Birrell James A. 
Published: June 2020

Abstract[FeFe] hydrogenases are the most active H2 converting catalysts in nature, but their extreme oxygen sensitivity limits their use in technological applications. The [FeFe] hydrogenases from sulfate reducing bacteria can be purified in an O2‐stable state called Hinact. To date, the structure and mechanism of formation of Hinact remain unknown. Our 1.65 Å crystal structure of this state reveals a sulfur ligand bound to the open coordination site. Furthermore, in‐depth spectroscopic characterization by X‐ray absorption spectroscopy (XAS), nuclear resonance vibrational spectroscopy (NRVS), resonance Raman (RR) spectroscopy and infrared (IR) spectroscopy, together with hybrid quantum mechanical and molecular mechanical (QM/MM) calculations, provide detailed chemical insight into the Hinact state and its mechanism of formation. This may facilitate the design of O2‐stable hydrogenases and molecular catalysts.