bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalysis and Electron Transfer in De Novo Designed Helical Scaffolds
Authors: Pinter Tyler B. J. , Koebke Karl J. , Pecoraro Vincent L. 
Published: August 2019

AbstractThe relationship between protein structure and function is one of the greatest puzzles within biochemistry. De novo metalloprotein design is a way to wipe the board clean and determine what is required to build in function from the ground up in an unrelated structure. This Review focuses on protein design efforts to create de novo metalloproteins within alpha‐helical scaffolds. Examples of successful designs include those with carbonic anhydrase or nitrite reductase activity by incorporating a ZnHis3 or CuHis3 site, or that recapitulate the spectroscopic properties of unique electron‐transfer sites in cupredoxins (CuHis2Cys) or rubredoxins (FeCys4). This work showcases the versatility of alpha helices as scaffolds for metalloprotein design and the progress that is possible through careful rational design. Our studies cover the invariance of carbonic anhydrase activity with different site positions and scaffolds, refinement of our cupredoxin models, and enhancement of nitrite reductase activity up to 1000‐fold.
A series of novel high‐temperature‐resistant multiwall carbon nanotubes dispersants: Polyphenylene sulfones with pyrene groups in main chain
Authors: Xu Da , Seery Thomas A. P. , Gao Yanwei , Ding Lianjun , Zhou Chenyi , Wang Zhaoyang , Jiang Zilong , Zhang Haibo 
Published: August 2019

ABSTRACTA series of polyphenylene sulfones were synthesized with pyrene groups in the main chain. Using a traditional Suzuki coupling reaction followed by a reduction, the pyrene‐containing monomer was synthesized as the diphenol. A series of copolymers were synthesized using this new monomer, a biphenyldiphenol, and 4,4′‐difluorodiphenylsulfone. These polymers were characterized using 1HNMR and FTIR spectroscopy. The introduction of rigid pyrene groups provided these new polymers with good thermal stability and mechanical strength. In this work, these polymers are shown to functionalize and disperse multiwall carbon nanotubes (MWCNTs). The associations of our copolymers to the MWCNTs appear to operate through pi stacking interactions between the pyrene group and the sidewalls of the MWCNTs, referred to in this article as f‐MWCNTs. The dispersibility of f‐MWCNTs in solvents and polymer matrixes was systematically studied by preparation of f‐MWCNTs/polyphenylene sulfone (PPSU) composites with various f‐MWCNTs content. Improvements in the dispersability of f‐MWCNTs in PPSU resin result in enhancement of the mechanical and thermal properties of f‐MWCNTs/PPSU composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48379.
AGNIQUE AMD 3L as green solvent for polyethersulfone ultrafiltration membrane preparation
Authors: Gronwald Oliver , Weber Martin 
Published: August 2019

ABSTRACTWith the advent of the green chemistry concept novel, innocuous, biodegradable solvents require introduction in industrial processes.N,N‐dimethyl lactamide (AGNIQUE AMD 3L) represents a bio‐based, biodegradable, label‐free polar, protic solvent. In this article, AGNIQUE AMD 3L is introduced as novel solvent for preparation of polyethersulfone (PESU) nonsolvent‐induced phase separation ultrafiltration membranes using polyvinylpyrrolidone or poly(ethylene oxide) as second dope additives. Analysis of Hansen solubility parameters indicates good solvent–polymer interactions for polymer dope compositions required for PESU membrane manufacturing. Depending on the process conditions, PESU ultrafiltration membranes with hydraulic permeability values up to 610 kg m−2× bar × h and molecular weight cutoff value of 20 kDa were obtained. Scanning electron microscope of membrane cross sections reveals perfect defect‐free, asymmetric morphologies. As a result, AGNIQUE AMD 3L provides a new alternative as replacement for polar, aprotic solvents employed in membrane manufacturing so far. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 48419.
Robust dissipative control for semilinear Markovian jump distributed parameter systems with time‐varying delay and incomplete transition probabilities
Authors: Song Xiaona , Wang Mi , Song Shuai , Lu Junwei , Man Jingtao 
Published: August 2019

AbstractThis paper investigates the robust stabilization problem of semilinear Markovian jump distributed parameter systems (which are modeled by parabolic partial differential equations) with time‐varying delay and incomplete transition probabilities. Based on Takagi‐Sugeno (T‐S) fuzzy theory, a T‐S fuzzy model is obtained to describe the nonlinear systems. Furthermore, by constructing a novel Lyapunov functional candidate, several sufficient delay‐dependent conditions, which ensure the considered systems stochastically stable and strictly dissipative, are established in terms of linear matrix inequalities. Finally, a fuzzy controller design approach is proposed, and two examples are presented to demonstrate the effectiveness of the designed controller.
Protosappanin‐A and oleanolic acid protect injured podocytes from apoptosis through inhibition of AKT‐mTOR signaling
Authors: Zheng Jiaxin , Zhang Shoulin , Chen Huijun , Cai Xiaojun , Zhang Chunjian , Li Shuhua , Zhou Yabin , Shang Jing , Liang Shunyu , Yao Fengzhen 
Published: August 2019

AbstractProtosappanin‐A (PrA) and oleanolic acid (OA), which are important effective ingredients isolated from Caesalpinia sappan L., exhibit therapeutic potential in multiple diseases. This study focused on exploring the mechanisms of PrA and OA function in podocyte injury. An in vitro model of podocyte injury was induced by the sC5b‐9 complex and assays such as cell viability, apoptosis, immunofluorescence, quantitative real‐time polymerase chain reaction, and western blot were performed to further investigate the effects and mechanisms of PrA and OA in podocyte injury. The models of podocyte injury were verified to be successful as seen through significantly decreased levels of nephrin, podocin, and CD2AP and increased level of desmin. The sC5b‐9‐induced podocyte apoptosis was inhibited in injured podocytes treated with PrA and OA, accompanied by increased protein levels of nephrin, podocin, CD2AP, and Bcl2 and decreased levels of desmin and Bax. The p‐AKT/p‐mTOR levels were also reduced by treatment of PrA and OA while AKT/mTOR was unaltered. Further, the effects of PrA and OA on injured podocytes were similar to that of LY294002 (a PI3K‐AKT inhibitor). PrA and OA were also seen to inhibit podocyte apoptosis and p‐AKT/p‐mTOR levels induced by IGF‐1 (a PI3K‐AKT activator). Our data demonstrate that PrA and OA can protect podocytes from injury or apoptosis, which may occur through inhibition of the abnormal activation of AKT‐mTOR signaling.
Single amino acid mutations in the Saccharomyces cerevisiae rhomboid peptidase, Pcp1p, alter mitochondrial morphology
Authors: Huddleston Mary Elizabeth , Xiao Ningyu , Both Andries Pieter , Gordon Donna M. 
Published: August 2019

AbstractKey to mitochondrial activities is the maintenance of mitochondrial morphology, specifically cristae structures formed by the invagination of the inner membrane that are enriched in proteins of the electron transport chain. In Saccharomyces cerevisiae , these cristae folds are a result of the membrane fusion activities of Mgm1p and the membrane‐bending properties of adenosine triphosphate (ATP) synthase oligomerization. An additional protein linked to mitochondrial morphology is Pcp1p, a serine protease responsible for the proteolytic processing of Mgm1p. Here, we have used hydroxylamine‐based random mutagenesis to identify amino acids important for Pcp1p peptidase activity. Using this approach we have isolated five single amino acid mutants that exhibit respiratory growth defects that correlate with loss of mitochondrial genome stability. Reduced Pcp1p protease activity was confirmed by immunoblotting with the accumulation of improperly processed Mgm1p. Ultra‐structural analysis of mitochondrial morphology in these mutants found a varying degree of defects in cristae organization. However, not all of the mutants presented with decreased ATP synthase complex assembly as determined by blue native polyacrylamide gel electrophoresis. Together, these data suggest that there is a threshold level of processed Mgm1p required to maintain ATP synthase super‐complex assembly and mitochondrial cristae organization.
Artesunate inhibits myofibroblast formation via induction of apoptosis and antagonism of pro‐fibrotic gene expression in human dermal fibroblasts
Authors: Larson Sara A. , Dolivo David M. , Dominko Tanja 
Published: August 2019

AbstractThe anti‐malaria drug artesunate and other chemical analogs of artemisinin have demonstrated cytostatic and cytotoxic effects in bacterial and cancer cells. Artemisinin‐derived compounds have also been demonstrated to attenuate fibrosis in preclinical animal models, but the mechanisms by which this inhibition occurs are not well‐understood. We investigated the effects of artesunate on the emergence of the myofibroblast, which is causally implicated in pro‐fibrotic pathologies. CRL‐2097 human dermal fibroblasts were analyzed for protein and transcript expression after treatment with artesunate to analyze fibroblast activation. Proliferation and apoptosis were also evaluated following treatment with artesunate in this cell line. Treatment of human dermal fibroblasts with artesunate antagonized fibroblast activation and pro‐fibrotic extracellular matrix (ECM) deposition, both at basal culture conditions and when cultured in the presence of exogenous transforming growth factor‐β1 (TGF‐β1), a major pro‐fibrotic cytokine. Artesunate‐treated fibroblasts also demonstrated decreased proliferation and increased apoptosis. Transcript analysis by quantitative real‐time polymerase chain reaction demonstrated that artesunate downregulated expression of pro‐fibrotic genes including canonical myofibroblast markers, ECM genes, and several TGF‐β receptors and ligands, and upregulated expression of cell cycle inhibitors and matrix‐metalloproteinases. Together, these data demonstrate that artesunate antagonizes fibroblast activation and decreases expression of pro‐fibrotic genes, while also promoting myofibroblast apoptosis, suggesting that these mechanisms may be responsible in part for the anti‐fibrotic effects of artesunate described previously.
Anticancer Potential of Diiron Vinyliminium Complexes
Authors: Rocco Dalila , Batchelor Lucinda K. , Agonigi Gabriele , Braccini Simona , Chiellini Federica , Schoch Silvia , Biver Tarita , Funaioli Tiziana , Zacchini Stefano , Biancalana Lorenzo , Ruggeri Marina , Pampaloni Guido , Dyson Paul J. , Marchetti Fabio 
Published: August 2019

AbstractAlthough ferrocene derivatives have attracted considerable attention as possible anticancer agents, the medicinal potential of diiron complexes has remained largely unexplored. Herein, we describe the straightforward multigram‐scale synthesis and the antiproliferative activity of a series of diiron cyclopentadienyl complexes containing bridging vinyliminium ligands. IC50 values in the low‐to‐mid micromolar range were determined against cisplatin sensitive and resistant human ovarian carcinoma (A2780 and A2780cisR) cell lines. Notable selectivity towards the cancerous cells lines compared to the non‐tumoral human embryonic kidney (HEK‐293) cell line was observed for selected compounds. The activity seems to be multimodal, involving reactive oxygen species (ROS) generation and, in some cases, a fragmentation process to afford monoiron derivatives. The large structural variability, amphiphilic character and good stability in aqueous media of the diiron vinyliminium complexes provide favorable properties compared to other widely studied classes of iron‐based anticancer candidates.
Proton Acidity and Proton Mobility in ECR‐40, a Silicoaluminophosphate that Violates Löwenstein's Rule
Authors: Fischer Michael 
Published: August 2019

AbstractThe silicoaluminophosphate zeotype ECR‐40 contains linkages of AlO4 tetrahedra via a common oxygen atom, thereby violating the famous “Löwenstein's rule”. In this work, a combination of static density functional theory (DFT) calculations and DFT‐based ab‐initio molecular dynamics (AIMD) simulations were employed to study the acidity and mobility of protons associated with such unusual linkages. It was found that the Al‐O‐Al linkages are preferentially protonated, as deprotonation causes a local accumulation of negative charge. The protons at these linkages possess a somewhat lower Brønsted acidity than those at Si‐O‐Al links. AIMD simulations for fully hydrated ECR‐40 predicted a partial deprotonation of the Al‐O‐Al linkages, whereas Si‐O‐Al linkages were fully deprotonated. Frequently, a coordination of water molecules to framework Al atoms was observed in the vicinity of the Al‐O‐Al links. Hence, these linkages appear prone to break upon dehydration, potentially explaining why Löwenstein's rule is mostly obeyed in materials formed in aqueous media.
Effect of the Metal within Regioisomeric Paddle‐Wheel‐Type Metal–Organic Frameworks
Authors: Ha Hyeonbin , Kim Youngik , Kim Dopil , Lee Jihyun , Song Yoodae , Kim Suyeon , Park Myung Hwan , Kim Youngjo , Kim Hyungjun , Yoon Minyoung , Kim Min 
Published: August 2019

AbstractThe effect of metal on the degree of flexibility upon evacuation of metal–organic frameworks (MOFs) has been revealed with positional control of the organic functionalities. Although Co‐, Cu‐, and Zn‐based DMOFs (DMOF = DABCO MOF, DABCO = 1,4‐diazabicyclo[2.2.2]octane) with ortho‐ligands (2,3‐NH2Cl) have frameworks that are inflexible upon evacuation, MOFs with para‐ligands (2,5‐NH2Cl) showed different N2 uptake amounts after evacuation by metal exchange. Considering that the structural analyses were not fully sufficiently different to explain the drastic changes in N2 adsorption after evacuation, quantum chemical simulation was explored. A new index (η) was defined to quantify the regularity around the metal based on differences in the oxygen‐metal‐oxygen angles. Within 2,5‐NH2Cl, the η value becomes larger as the metal are varied from Co to Zn. A large η value means that the structures around the metal center are less ordered. These results can be used to explain flexibility changes upon evacuation by altering the metal cation in this regioisomeric system.
Precise Manipulation of Temperature‐Driven Chirality Switching of Molecular Universal Joints through Solvent Mixing
Authors: Fan Chunying , Yao Jiabin , Li Guojuan , Guo Cheng , Wu Wanhua , Su Dan , Zhong Zhihui , Zhou Dayang , Wang Yuliang , Chruma Jason J. , Yang Cheng 
Published: August 2019

AbstractInvited for the cover of this issue is Cheng Yang and co‐workers at Sichuan University. The image depicts solvent mixing as a precise, but powerful and pervasive method for manipulating the temperature‐driven chirality switching behavior of molecular universal joints. Read the full text of the article at 10.1002/chem.201902676.
Deoxygenative Arylation of Carboxylic Acids by Aryl Migration
Authors: Ruzi Rehanguli , Ma Junyang , Yuan Xiang‐Ai , Wang Wenliang , Wang Shanshan , Zhang Muliang , Dai Jie , Xie Jin , Zhu Chengjian 
Published: August 2019

AbstractAn unprecedented deoxygenative arylation of aromatic carboxylic acids has been achieved, allowing the construction of an enhanced library of unsymmetrical diaryl ketones. The synergistic photoredox catalysis and phosphoranyl radical chemistry allows for precise cleavage of a stronger C−O bond and formation of a weaker C−C bond by 1,5‐aryl migration under mild reaction conditions. This new protocol is independent of substrate redox‐potential, electronic, and substituent effects. It affords a general and promising access to 60 examples of synthetically versatile o‐amino and o‐hydroxy diaryl ketones under redox‐neutral conditions. Furthermore, it also brings one concise route to the total synthesis of quinolone alkaloid, (±)‐yaequinolone A2, and a viridicatin derivative in satisfying yields.
Pseudospectral Bound and Transition Threshold for the 3D Kolmogorov Flow
Authors: Li Te , Wei Dongyi , Zhang Zhifei 
Published: August 2019

In this paper, we study pseudospectral bounds for the linearized operator of the Navier‐Stokes equations around the 3D Kolmogorov flow. Using the pseudospectral bound and the wave operator method introduced in [22], we prove the sharp enhanced dissipation rate for the linearized Navier‐Stokes equations. As an application, we prove that if the initial velocity satisfiesurn:x-wiley:00103640:media:cpa21863:cpa21863-math-0001
(ν the viscosity coefficient) and kf ∈ (0, 1), then the solution does not transition away from the Kolmogorov flow. © 2019 Wiley Periodicals, Inc.
High‐Performance Plasma‐Enabled Biorefining of Microalgae to Value‐Added Products
Authors: Zhou Renwu , Zhou Rusen , Zhang Xianhui , Fang Zhi , Wang Xiaoxiang , Speight Robert , Wang Hongxia , Doherty William , Cullen Patrick J. , Ostrikov Kostya (Ken) , Bazaka Kateryna 
Published: August 2019

AbstractConversion of renewable biomass by time‐ and energy‐efficient techniques remains an important challenge. Herein, plasma catalytic liquefaction (PCL) is employed to achieve rapid liquefaction of microalgae under mild conditions. The choice of the catalyst affects both the liquefaction efficiency and the yield of products. The acid catalyst is more effective and gave a liquid yield of 73.95 wt % in 3 min, as opposed to 69.80 wt % obtained with the basic catalyst in 7 min. Analyses of the thus‐formed products and the processing environment reveal that the enhanced PCL performance is linked to the rapid increase in temperature under the effect of plasma‐induced electric fields and the generation of large quantities of reactive species. Moreover, the obtained solid residue can be simply upgraded to a carbon product suitable for supercapacitor applications. Therefore, the proposed strategy may provide a new avenue for fast and comprehensive utilization of biomass under benign conditions.
An enhanced anonymous identity‐based key agreement protocol for smart grid advanced metering infrastructure
Authors: Mahmood Khalid , Arshad Jehangir , Chaudhry Shehzad Ashraf , Kumari Saru 
Published: August 2019

SummarySprouting populace mass within the urban areas furnishes critical challenges of providing uninterruptible community services to fulfill the primitive needs of inhabitants in smart cities. Smart cities facilitate and uplift the living standards of inhabitants through various smart systems or infrastructures, and smart grid is one of them. Secure transmission is a key requirement in the advanced metering infrastructure (AMI) of most smart grids, and key establishment cryptographic protocols can be used to achieve such a requirement. Designing efficient and secure key establishment protocols for AMI remains challenging. For example, in this paper, we reveal several weaknesses in the identity‐based key establishment protocol of Mohammadali et al (published in IEEE Trans Smart Grid, 2017), which is based on elliptic curves. We then improve their protocol and prove its security in the random oracle model. We also demonstrate that the improved protocol achieves both anonymity and untraceability, before presenting a comparative summary of the security and computational overheads of the proposed protocol and several other existing protocols.
Selection on tropane alkaloids in native and non‐native populations of Datura stramonium
Authors: Castillo Guillermo , Calahorra‐Oliart Adriana , Núñez‐Farfán Juan , Valverde Pedro L. , Arroyo Juan , Cruz Laura L. , Tapia‐López Rosalinda 
Published: August 2019

AbstractTheories of plant invasion based on enemy release in a new range assume that selection exerted by specialist herbivores on defence traits should be reduced, absent, or even selected against in the new environment. Here, we measured phenotypic selection on atropine and scopolamine concentration of Datura stramonium in eight native (Mexico) and 14 non‐native (Spain) populations. Native populations produced between 20 and 40 times more alkaloid than non‐native populations (atropine: 2.0171 vs. 0.0458 mg/g; scopolamine: 1.004 vs. 0.0488 mg/g, respectively). Selection on alkaloids was negative for atropine and positive for scopolamine concentration in both ranges. However, the effect sizes of selection gradients were only significant in the native range. Our results support the assumption that the reduction of plant defence in the absence of the plant's natural enemies in invasive ranges is driven by natural selection.
Temporally adaptive acoustic sampling to maximize detection across a suite of focal wildlife species
Authors: Balantic Cathleen , Donovan Therese 
Published: August 2019

Abstract

Acoustic recordings of the environment can produce species presence–absence data for characterizing populations of sound‐producing wildlife over multiple spatial scales. If a species is present at a site but does not vocalize during a scheduled audio recording survey, researchers may incorrectly conclude that the species is absent (“false negative”). The risk of false negatives is compounded when audio devices have sampling constraints, do not record continuously, and must be manually scheduled to operate at pre‐selected times of day, particularly when research programs target multiple species with acoustic availability that varies across temporal conditions.
We developed a temporally adaptive acoustic sampling algorithm to maximize detection probabilities for a suite of focal species amid sampling constraints. The algorithm combines user‐supplied species vocalization models with site‐specific weather forecasts to set an optimized sampling schedule for the following day. To test our algorithm, we simulated hourly vocalization probabilities for a suite of focal species in a hypothetical monitoring area for the year 2016. We conducted a factorial experiment that sampled from the 2016 acoustic environment to compare the probability of acoustic detection by a fixed (stationary) schedule versus a temporally adaptive optimized schedule under several sampling efforts and monitoring durations.
We found that over the course of a study season, the probability of acoustically capturing a focal species (given presence) at least once via automated acoustic monitoring was greater (and acoustic capture occurred earlier in the season) when using the temporally adaptive optimized schedule as compared to a fixed schedule.
The advantages of a temporally adaptive optimized acoustic sampling schedule are magnified when a study duration is short, sampling effort is low, and/or species acoustic availability is minimal. This methodology presents the opportunity to maximize acoustic monitoring sampling efforts amid constraints.