bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Synthesis of Conjugated Chiral Macrocycles: Sidewall Segments of (−)/(+)‐(12,4) Carbon Nanotubes with Strong Circularly Polarized Luminescence
Authors: Wang Jinyi , Zhuang Guilin , Chen Muqing , Lu Dapeng , Li Zhe , Huang Qiang , Jia Hongxing , Cui Shengsheng , Shao Xiang , Yang Shangfeng , Du Pingwu 
Published: November 2019

AbstractCarbon nanotubes (CNTs) have unusual physical properties that are valuable for nanotechnology and electronics, but the chemical synthesis of chirality‐ and diameter‐specific CNTs and π‐conjugated CNT segments is still a great challenge. Reported here are the selective syntheses, isolations, characterizations, and photophysical properties of two novel chiral conjugated macrocycles ([4]cyclo‐2,6‐anthracene; [4]CAn2,6), as (−)/(+)‐(12,4) carbon nanotube segments. These conjugated macrocyclic molecules were obtained using a bottom‐up assembly approach and subsequent reductive elimination reaction. The hoop‐shaped molecules can be directly viewed by a STM technique. In addition, chiral enantiomers with (−)/(+) helicity of the [4]CAn2,6 were successfully isolated by HPLC. The new tubular CNT segments exhibit large absorption and photoluminescence redshifts compared to the monomer unit. The carbon enantiomers are also observed to show strong circularly polarized luminescence (glum≈0.1). The results reported here expand the scope of materials design for bottom‐up synthesis of chiral macrocycles and enrich existing knowledge of their optoelectronic properties.
Ring‐Opening Lithiation–Borylation of 2‐Trifluoromethyl Oxirane: A Route to Versatile Tertiary Trifluoromethyl Boronic Esters
Authors: Nandakumar Meganathan , Rubial Belén , Noble Adam , Myers Eddie L. , Aggarwal Varinder K. 
Published: November 2019

AbstractStereogenic trifluoromethyl‐substituted carbon centers are highly sought‐after moieties in pharmaceutical and agrochemical discovery. Here, we show that lithiation–borylation reactions of 2‐trifluoromethyl oxirane give densely functionalized and highly versatile trifluoromethyl‐substituted α‐tertiary boronic esters. The intermediate boronate complexes undergo the desired 1,2‐rearrangement of the carbon‐based group with complete retentive stereospecificity, a process that was only observed in non‐polar solvents in the presence of TESOTf. Although the trifluoromethyl group adversely affects subsequent transformations of the α‐boryl group, Zweifel olefinations provide trifluoromethyl‐bearing quaternary stereocenters substituted with alkenes, alkynes and ketones.
Compressive behavior of rigid polyurethane foams nanostructured with bacterial nanocellulose at low and intermediate strain rates
Authors: Chiacchiarelli Leonel Matías , Cerrutti Patricia , Flores‐Johnson Emmanuel A. 
Published: November 2019

ABSTRACTNanocellulose reinforced foams are lightweight with improved mechanical properties; however, the strain‐rate effect on their mechanical response is not yet fully understood. In this work, rigid polyurethane foams (PUFs) nanostructured with bacterial nanocellulose at 0.2 wt % (BNCF) and without it (PUF) are synthesized and subjected to compression tests at different strain rates. The BNC acts as a nucleation agent, reducing the cell size but maintaining a similar apparent density of 40.4 ± 3.3 kg m−3. Both BNCF and PUF exhibit strain‐rate effect on yield stress and densification strain. The BNCF exhibits localized progressive crushing and reduced friability, causing a remarkable recovery in the transverse direction. Numerical simulations show that functionally graded foams subjected to impact could be designed using different layers of PUF and BNCF to vary energy absorption and acceleration rate. The results presented herein warrant further research of the mechanical properties of nanostructured foams for impact applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48701.
New aryloxy‐quinone derivatives with promising activity on Trypanosoma cruzi
Authors: Espinosa‐Bustos Christian , Vázquez Karina , Varela Javier , Cerecetto Hugo , Paulino Margot , Segura Rodrigo , Pizarro Jaime , Vera Brenda , González Mercedes , Zarate Ana M. , Salas Cristian O. 
Published: November 2019

AbstractContinuing with a program to develop new quinone derivatives as biologically active compounds, we designed and synthesized a new series of aryloxy‐quinones, which were evaluated in vitro against Trypanosoma cruzi in epimastigote form. Chemical modifications in three specific moieties on the aryloxy‐quinone core were considered for developing new anti‐T. cruzi agents. The majority of our new quinones showed higher potency (IC50 values of <0.70 µM) than nifurtimox, a known pharmaceutical used as a baseline drug (IC50 values of 7.00 µM); however, only two of them elicited higher selectivity than nifurtimox against Vero cells. A structure–activity relationship analysis provided information about the stereoelectronic features of these compounds, which are responsible for an increase in trypanosomicidal activity. Using a pharmacophore model, we mapped the substitution patterns of the five pharmacophoric features of trypanosomicidal activity. We chose the Epc1 compounds and found no relationship with the trypanosomicidal effects. These results provided useful information about the structural characteristics for developing new aryloxy‐quinones with higher potency against the protozoan parasite T. cruzi.
“Trim”ming PolyQ proteins with engineered PML
Authors: Dhar Neha , Arsiwala Ammar , Murali Shruthi , Kane Ravi S. 
Published: November 2019

AbstractProtein abnormalities are the major cause of neurodegenerative diseases such as spinocerebellar ataxia (SCA). Protein misfolding and impaired degradation leads to the build‐up of protein aggregates inside the cell, which may further cause cellular degeneration. Reducing levels of either the soluble misfolded form of the protein or its precipitated aggregate, even marginally, could significantly improve cellular health. Despite numerous pre‐existing strategies to target these protein aggregates, there is considerable room to improve their specificity and efficiency. In this study, we demonstrated the enhanced intracellular degradation of both monomers and aggregates of mutant ataxin1 (Atxn1 82Q) by engineering an E3 ubiquitin ligase enzyme, promyelocytic leukemia protein (PML). Specifically, we showed enhanced degradation of both soluble and aggregated Atxn1 82Q in mammalian cells by targeting this protein using PML fused to single chain variable fragments (scFvs) specific for monomers and aggregates of the target protein. The ability to solubilize Atxn1 82Q aggregates was due to the PML‐mediated enhanced SUMOylation of the target protein. This ability to reduce the intracellular levels of both misfolded forms of Atxn1 82Q may not only be useful for treating SCA, but also applicable for the treatment of other PolyQ disorders.
Efficient butanol production under aerobic conditions by coculture of Clostridium acetobutylicum and Nesterenkonia sp. strain F
Authors: Ebrahimi Ehsan , Amiri Hamid , Asadollahi Mohammad A. , Shojaosadati Seyed A. 
Published: November 2019

AbstractClostridium acetobutylicum is widely used for the microbial production of butanol in a process known as acetone–butanol–ethanol (ABE) fermentation. However, this process suffers from several disadvantages including high oxygen sensitivity of the bacterium which makes the process complicated and necessitate oxygen elimination in the culture medium. Nesterenkonia sp. strain F has attracted interests as the only known non‐Clostridia microorganism with inherent capability of butanol production even in the presence of oxygen. This bacterium is not delimited by oxygen sensitivity, a challenge in butanol biosynthesis, but the butanol titer was far below Clostridia. In this study, Nesterenkonia sp. strain F was cocultivated with C. acetobutylicum to form a powerful “coculture” for butanol production thereby eliminating the need for oxygen removal before fermentation. The response surface method was used for obtaining optimal inoculation amount/time and media formulation. The highest yield, 0.31 g/g ABE (13.6 g/L butanol), was obtained by a coculture initiated with 1.5 mg/L Nesterenkonia sp. strain F and inoculated with 15 mg/L C. acetobutylicum after 1.5 hr in a medium containing 67 g/L glucose, 2.2 g/L yeast extract, 4 g/L peptone, and 1.4% (vol/vol) P2 solution. After butanol toxicity assessment, where Nesterenkonia sp. strain F showed no butanol toxicity, the coculture was implemented in a 2 L fermenter with continual aeration leading to 20 g/L ABE.
Leveraging flow mechanics to determine critical process and scaling parameters in a continuous viral inactivation reactor
Authors: Brown Matthew R. , Orozco Raquel , Coffman Jon 
Published: November 2019

AbstractA continuous viral inactivation (CVI) chamber has been designed to operate with acceptable residence time distribution (RTD) characteristics. However, altering the CVI's geometry and operation to accommodate the scale was not obvious. In this work, we elucidate the influence of Dean vortices and leverage the transition into the weak turbulent regime to establish relationships between input variables and process outputs. This study was targeted to understand and quantify the impact of viscosity, Dean number, internal diameter, and path length on the RTD. When the Dean number exceeds 70, radial mixing generated by the Dean vortices began to consistently alter the axial dispersive effects experienced by the pulse injection. Increasing to a Dean number of >100, the axial dispersive effects were dominated by the Dean vortices which allowed the calculation of the minimum and maximum residence time to be generated. This work provides a method to calculate operational solutions for a tubular incubation reactor in terms of path length, internal diameter, flow rate, and target minimum and maximum residence time specifications that assures both viral residence times while also establishing criteria to maximize product quality during continuous operation.
Effects of early postnatal exposure to fine particulate matter on emotional and cognitive development and structural synaptic plasticity in immature and mature rats
Authors: Liu Jie , Yang Chen , Yang Jing , Song Xiaojie , Han Wei , Xie Mingdan , Cheng Li , Xie Lingling , Chen Hengsheng , Jiang Li 
Published: November 2019

AbstractIntroductionFine particulate matter (PM2.5) is closely associated with many neurological disorders including neurodegenerative disease, stroke, and brain tumors. However, the toxic effects of PM2.5 on neurodevelopment remain unclear. In this study, we aimed to determine the neurotoxic effects of early postnatal exposure to PM2.5 in immature and mature rats.MethodsWe exposed neonatal rats to PM2.5 (2 or 10 mg/kg body weight) through intranasal instillation from postnatal day (PND) 3–15, once a day. Emotional and cognitive development were evaluated using the elevated plus maze, forced swimming, and Morris water maze tests. Hippocampal tissue was collected and subjected to transmission electron microscopy observation and western blot analysis.ResultsRats had lower body weight after exposure to high dose of PM2.5. The behavioral test results indicated that high‐dose PM2.5 exposure led to increased anxiety‐like symptoms in immature and mature rats, apparent depressive‐like behaviors in mature rats, and impaired spatial learning and memory abilities in immature rats, and low‐dose PM2.5 exposure increased anxiety‐like behaviors in immature rats. Further, high‐dose PM2.5 exposure contributed to fewer synapses, thinner postsynaptic density, and shorter active zone in immature and mature rats, and also decreased expressions of synaptophysin (SYP), growth associated protein‐43 (GAP43), and postsynaptic density‐95 (PSD95) in immature rats, SYP and PSD95 in mature rats. Moreover, low‐dose PM2.5 exposure diminished the expression of PSD95 in immature rats. In addition, high‐dose PM2.5 exposure reduced brain‐derived neurotrophic factor (BDNF) expression and cAMP response element binding protein (CREB) phosphorylation in both immature and mature rats, and low‐dose PM2.5 exposure lessened BDNF expression and CREB phosphorylation in immature rats.ConclusionsOur findings indicate that PM2.5 impairs emotional and cognitive development by disrupting structural synaptic plasticity, possibly via the CREB/BDNF signaling pathway.
New Vocabulary for Bacterial Communication
Authors: Tobias Nicholas J. , Brehm Jannis , Kresovic Darko , Brameyer Sophie , Bode Helge B. , Heermann Ralf 
Published: November 2019

AbstractQuorum sensing (QS) is widely accepted as a procedure that bacteria use to converse. However, prevailing thinking places acyl homoserine lactones (AHLs) at the forefront of this communication pathway in Gram‐negative bacteria. With the advent of high‐throughput genomics and the subsequent influx of bacterial genomes, bioinformatics analysis has determined that the genes encoding AHL biosynthesis, originally discovered to be indispensable for QS (LuxI‐like proteins and homologues), are often absent in QS‐capable bacteria. Instead, the sensing protein (LuxR‐like proteins) is present with an apparent inability to produce any outgoing AHL signal. Recently, several signals for these LuxR solos have been identified. Herein, advances in the field of QS are discussed, with a particular focus on recent research in the field of bacterial cell–cell communication.
Spontaneous pneumomediastinum and subcutaneous emphysema in avian influenza A (H5N6) human pneumonia
Authors: Zhang Xiang , Wang Jiwen , Zeng Qiaojun , Wu Xiaoyan , Jiang Shanping , Shen Jun 
Published: November 2019

AbstractThe pneumomediastinum and subcutaneous emphysema can repetitively occur in human H5N6 virus pneumonia. Prompt treatment of this uncommon complication is important for successful rescue of patients with H5N6 virus pneumonia.
Rational De Novo Design of a Cu Metalloenzyme for Superoxide Dismutation
Authors: Mathieu Emilie , Tolbert Audrey E. , Koebke Karl J. , Tard Cédric , Iranzo Olga , Penner‐Hahn James E. , Policar Clotilde , Pecoraro Vincent 
Published: November 2019

AbstractSuperoxide dismutases (SODs) are highly efficient enzymes for superoxide dismutation and the first line of defense against oxidative stress. These metalloproteins contain a redox‐active metal ion in their active site (Mn, Cu, Fe, Ni) with a tightly controlled reduction potential found in a close range around the optimal value of 0.36 V versus the normal hydrogen electrode (NHE). Rationally designed proteins with well‐defined three‐dimensional structures offer new opportunities for obtaining functional SOD mimics. Here, we explore four different copper‐binding scaffolds: H3(His3), H4(His4), H2DH (His3Asp with two His and one Asp in the same plane) and H3D (His3Asp with three His in the same plane) by using the scaffold of the de novo protein GRα3D. EPR and XAS analysis of the resulting copper complexes demonstrates that they are good CuII‐bound structural mimics of Cu‐only SODs. Furthermore, all the complexes exhibit SOD activity, though three orders of magnitude slower than the native enzyme, making them the first de novo copper SOD mimics.
Racemisation in Chemistry and Biology
Authors: Ballard Andrew , Narduolo Stefania , Ahmed Hiwa O. , Keymer Nathaniel I. , Asaad Nabil , Cosgrove David A. , Buurma Niklaas J. , Leach Andrew G. 
Published: November 2019

AbstractThe two enantiomers of a compound often have profoundly different biological properties and thus their liability to racemisation in aqueous solutions is an important piece of information. The authors reviewed the available data concerning the process of racemisation in vivo, in the presence of biological molecules (e.g., racemase enzymes, serum albumin, cofactors and derivatives) and under purely chemical but aqueous conditions (acid, base and other aqueous systems). Mechanistic studies are described critically in light of reported kinetic data. The types of experimental measurement that can be used to effectively determine rate constants of racemisation in various conditions are discussed and the data they provide is summarised. The proposed origins of enzymatic racemisation are presented and suggest ways to promote the process that are different from processes taking place in bulk water. Experimental and computational studies that provide understanding and quantitative predictions of racemisation risk are also presented.
Fabrication of a Hierarchical Ni(OH)2@Ni3S2/Ni Foam Electrode from a Prussian Blue Analogue‐Based Composite with Enhanced Electrochemical Capacitive and Electrocatalytic Properties
Authors: Chen Xiaojuan , Yang Longkun , Huang Yunxia , Ge Shuaipeng , Zhang Hao , Cui Yimin , Huang Anping , Xiao Zhisong 
Published: November 2019

AbstractDeveloping high‐efficiency, cost‐effective, and durable electrodes is significant for electrochemical capacitors and electrocatalysis. Herein, a 3D bifunctional electrode consisting of nickel hydroxide nanosheets@nickel sulfide nanocubes arrays on Ni foam (Ni(OH)2@Ni3S2/NF) obtained from a Prussian blue analogue‐based precursor is reported. The 3D higher‐order porous structure and synergistic effect of different compositions endow the electrode with large specific surface area, facile ion/electron transport path, and improved conductivity. As a result, the Ni(OH)2@Ni3S2/NF electrode exhibits a high specific capacity of 211 mA h g−1 at a current density of 1 A g−1 and 73 % capacity retention after 5000 cycles at 5 A g−1. Moreover, the Ni(OH)2@Ni3S2/NF electrode has superior electrocatalytic activity for the hydrogen evolution reaction with low overpotentials of 140 and 210 mV at current densities of 10 and 100 mA cm−2, respectively. The synthetic strategy for the unique higher‐order porous structure can be extended to fabricate other composite materials for energy storage and conversion.
Fighting Deactivation: Classical and Emerging Strategies for Efficient Stabilization of Molecular Electrocatalysts
Authors: Bairagya Monojit Das , Bujol Ryan J. , Elgrishi Noémie 
Published: November 2019

AbstractDevelopment of highly active molecular electrocatalysts for fuel‐forming reactions has relied heavily on understanding mechanistic aspects of the electrochemical transformations. Careful fine‐tuning of the ligand environment oriented mechanistic pathways towards higher activity and optimal product distribution for several catalysts. Unfortunately, many catalysts deactivate in bulk electrolysis conditions, diminishing the impact of the plethora of highly tuned molecular electrocatalytic systems. This Minireview covers classical and emerging methods developed to circumvent catalyst deactivation and degradation, with an emphasis on successes with molecular electrocatalysts.
A Double‐Band Emitter with Ultranarrow‐Band Blue and Narrow‐Band Green Luminescence
Authors: Ruegenberg Freia , Seibald Markus , Baumann Dominik , Peschke Simon , Schmid Philipp C. , Huppertz Hubert 
Published: November 2019

AbstractUnderstanding the origin and mechanisms of luminescence is a crucial point when it comes to the development of new phosphors with targeted luminescence properties. Herein, a new phosphor belonging to the substance class of alkali metal lithosilicates with the generalized sum formula Cs4−x−y−zRbxNayLiz[Li3SiO4]4:Eu2+is reported. Single crystals of the cyan‐emitting UCr4C4‐type phosphor show a peculiar double‐band luminescence with one ultranarrow emission band at 473 nm and a narrow emission band at 531 nm under excitation with UV light (λexc=408 nm). Regarding occupation of the channels by the light metal ions, investigations of single‐crystal XRD data led to the assumption that domain formation with distinct lithium‐ and sodium‐filled channels occurs. Depending on which of these channels hosts the activator ion Eu2+, a green or blue emission results. The herein‐presented results shed new light on the luminescence process in the well‐studied UCr4C4‐type alkali metal lithosilicate phosphors.
Charge Distribution and Stability of SiO2 Nanoarray Electret
Authors: Liang Fei , Li Hua Yang , Wang Ying , Kuang Shuang Yang , Fan You Jun , Wang Zhong Lin , Zhu Guang 
Published: November 2019

AbstractThe devices based on SiO2 electret have significant applications in various MEMS sensors. However, the charge stability of SiO2 electret suffered from the water percolation, which seriously restricts its application. In this work, the long‐term charge stability of the SiO2 nanoarray electret (SiO2 NAE) without any water repellent treatment is demonstrated. When the oxidation time is 1.5 h, the potential decay of the SiO2 NAE is less than 46% during 60 days with an original potential of −120 V. The long‐term charge stability of the SiO2 NAE is attributed to its unique charge decay process and the large H2O diffusion barrier in the SiO2 NAE: firstly, the charge trapped in the planar part of the SiO2 NAE decays rapidly. Then, residual charge stored in the SiO2 nanoarray. Eventually, the large H2O diffusion barrier in the interface of Si/SiO2 effectively hinders the charge decay. In addition, we demonstrate the unique charge stability of nanoelectret, which has a promising application in developing high performance electret‐based devices.
Benchmarking the first generation of production quality Arm‐based supercomputers
Authors: McIntosh‐Smith Simon , Price James , Poenaru Andrei , Deakin Tom 
Published: November 2019

AbstractIn this paper, we present scaling results from two production quality supercomputers that use the first generation of Arm‐based CPUs that have been optimized for scientific workloads. Both systems use Marvell ThunderX2 CPUs, which deliver high core counts and class‐leading memory bandwidth. The first system is Isambard, a Cray XC50 “Scout” system operated by the GW4 Alliance and the UK Met Office as a Tier‐2 national HPC service. The second system is one of three Arm‐based HPE Apollo 70 systems delivered as part of the Catalyst UK project, running at the University of Bristol. We compare scaling results from these two systems with three Cray XC50 systems based on Intel Skylake and Broadwell CPUs. We focus on a range of applications and mini‐apps that are important to the UK national HPC service, ARCHER, and to our project partners. We also compare the performance and maturity of the state‐of‐the‐art toolchains available on Arm‐based HPC systems.
Graded diacylglycerol kinases α and ζ activities ensure mucosal‐associated invariant T‐cell development in mice
Authors: Pan Yun , Deng Wenhai , Xie Jinhai , Zhang Shimeng , Wan Edwin C.K. , Li Lei , Tao Huishan , Hu Zhiming , Chen Yongping , Ma Li , Gao Jimin , Zhong Xiao‐Ping 
Published: November 2019

AbstractMucosal‐associated invariant T (MAIT) cells participate in both protective immunity and pathogenesis of diseases. Most murine MAIT cells express an invariant TCRVα19‐Jα33 (iVα19) TCR, which triggers signals crucial for their development. However, signal pathways downstream of the iVα19TCR and their regulation in MAIT cells are unknown. Diacylglycerol (DAG) is a critical second messenger that relays the TCR signal to multiple downstream signaling cascades. DAG is terminated by DAG kinase (DGK)‐mediated phosphorylation and conversion to phosphatidic acid. We have demonstrated here that downregulation of DAG caused by enhanced DGK activity impairs late‐stage MAIT cell maturation in both thymus and spleen. Moreover, deficiency of DGKζ but not DGKα by itself causes modest decreases in MAIT cells, and deficiency of both DGKα and ζ results in severe reductions of MAIT cells in an autonomous manner. Our studies have revealed that DAG signaling is not only critical but also must be tightly regulated by DGKs for MAIT cell development and that both DGKα and, more prominently, DGKζ contribute to the overall DGK activity for MAIT cell development.