bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perylene Bisimide and Naphthyl‐Based Molecular Dyads: Hydrogen Bonds Driving Co‐planarization and Anomalous Temperature‐Response Fluorescence
Authors: Shang Congdi , Wang Gang , Liu Ke , Jiang Qingwei , Liu Fengyi , Chou Pi‐Tai , Fang Yu 
Published: February 2020

AbstractThe origin of the positive temperature effect in fluorescence emission of a newly designed perylene bisimide (PBI) derivative with two naphthyl units containing ortho‐methoxy group (NM) at its bay positions (PBI‐2NM) was elucidated. A key point is the finding of a weak hydrogen bond (<5.0 kcal mol−1) between the methoxy group of the NM unit and a nearby hydrogen atom of the PBI core. It is the bonding that drives co‐planarization of the different aromatic units, resulting in delocalization of the π‐electrons of the compound as synthesized, inducing fluorescence quenching via intramolecular charge transfer (ICT). With increasing temperature, the co‐planar structure could be distorted in part, resulting in a decreased degree of ICT, and hence leading to enhanced fluorescence emission. The unique positive temperature effect in emission induced by H‐bond‐driven co‐planarization may pave a new avenue in designing functional molecular systems complementary to conventional methods.
Comparative analysis of model reduction strategies for circuit based periodic control problems
Authors: Hossain Mohammad‐Sahadet , Tahsin Aniqa , Omar Sufi Galib , Hossain Khan Ekram 
Published: February 2020

AbstractThis paper is a comparative analysis of two prominent iterative algorithms for model order reduction of linear time‐varying (LTV) periodic systems where the system's matrices are singular. Our proposed method is based on a reformulation of the LTV model to an equivalent linear time‐invariant (LTI) model using a suitable discretization procedure. The resulting LTI model is reduced in two ways, once by applying a balanced truncation method and once by applying a Krylov‐based method known as iterative rational Krylov algorithm (IRKA). During the application of balanced truncation, the low‐rank Cholesky factorized alternating directions implicit (LRCF‐ADI) method is used to estimate the solutions of the corresponding LTI form of Lyapunov equations. Since the system's matrices are singular, the concept of pseudo‐inverse is adopted to compute the shift parameters needed in the LRCF‐ADI iterations. For the Krylov‐based IRKA, our work is twofold. We solve the time‐invariant Lyapunov equation for the observability Gramian and apply a moment‐matching Krylov technique. The accuracy and effectiveness of the two proposed techniques are demonstrated with the help of frequency response graphs, bode plots, and eigenstructure of the main and reduced models.
Debating Eukaryogenesis—Part 1: Does Eukaryogenesis Presuppose Symbiosis Before Uptake?
Authors: Speijer Dave 
Published: February 2020

AbstractEukaryotic origins are heavily debated. The author as well as others have proposed that they are inextricably linked with the arrival of a pre‐mitochondrion of alphaproteobacterial‐like ancestry, in a so‐called symbiogenic scenario. The ensuing mutual adaptation of archaeal host and endosymbiont seems to have been a defining influence during the processes leading to the last eukaryotic common ancestor. An unresolved question in this scenario deals with the means by which the bacterium ends up inside. Older hypotheses revolve around the application of known antagonistic interactions, the bacterium being prey or parasite. Here, in reviewing the field, the author argues that such models share flaws, hence making them less likely, and that a “pre‐symbiotic stage” would have eased ongoing metabolic integration. Based on this the author will speculate about the nature of the (endo) symbiosis that started eukaryotic evolution–in the context of bacterial entry being a relatively “early” event–and stress the differences between this uptake and subsequent ones. He will also briefly discuss how the mutual adaptation following the merger progressed and how many eukaryotic hallmarks can be understood in light of coadaptation. Also see the video abstract here https://youtu.be/ekqtNleVJpU
Microbial β‐Galactosidases of industrial importance: Computational studies on the effects of point mutations on the lactose hydrolysis reaction
Authors: de Andrade Bruna C. , Timmers Luis F. S. M. , Renard Gaby , Volpato Giandra , de Souza Claucia F. V. 
Published: February 2020

AbstractHydrolysis efficiency of β‐galactosidases is affected due to a strong inhibition by galactose, hampering the complete lactose hydrolysis. One alternative to reduce this inhibition is to perform mutations in the enzyme's active site. The aim of this study was to evaluate the effect of point mutations on the active site of different microbial β‐galactosidases, using computational techniques. The enzymes of Aspergillus niger (AnβGal), Aspergillus oryzae (AoβGal), Bacillus circulans (BcβGal), Bifidobacterium bifidum (BbβGal), and Kluyveromyces lactis (KlβGal) were used. The mutations were carried out in all residues that were up to 4.5 Å from the galactose/lactose molecules and binding energy was computed. The mutants Tyr96Ala (AnβGal), Asn140Ala and Asn199Ala (AoβGal), Arg111Ala and Glu355Ala (BcβGal), Arg122Ala and Phe358Ala (BbβGal), Tyr523Ala, Phe620Ala, and Trp582Ala (KlβGal) had the best results, with higher effect on galactose binding energy and lower effect on lactose affinity. To maximize enzyme reactions by reducing galactose affinity, double mutations were proposed for BcβGal, BbβGal, and KlβGal. The double mutations in BcβGal and BbβGal caused the highest reduction in galactose affinity, while no satisfactory results were observed to KlβGal. Using computational tools, mutants that reduced galactose affinity without significantly affecting lactose binding were proposed. The mutations proposed can be used to reduce the negative feedback process, improving the catalytic characteristics of β‐galactosidases and rendering them promising for industrial applications.
Activation of C−H Bond of Propane by Strong Basic Sites Generated by Bulk Proton Conduction on V‐Modified Hydroxyapatites for the Formation of Propene.
Authors: Petit Sarah , Thomas Cyril , Millot Yannick , Krafft Jean‐Marc , Laberty‐Robert Christel , Costentin Guylène 
Published: February 2020

AbstractInsights into the catalytic transformation of propane to propene on V‐apatite catalysts are provided based on structure‐reactivity relationships. Substitution of phosphates by vanadates in the hydroxyapatite structure leads to the formation of Ca10(PO4)6‐x(VO4)x(OH)2‐yOy V‐oxy‐hydroxy‐apatite solid solutions (x=0→6). Bulk vanadium incorporation promotes (i) calcium rich terminations (XPS, CO adsorption), (ii) proton deficiency inside the OH− channels (1H NMR) giving rise to O2− native species, (iii) the thermally‐activated formation of additional O2− species along the OH− channels resulting in H‐bonding interaction (in situ DRIFT) and (iv) the proton conduction process that eventually results in the surface exposure of O2− species (in situ impedance spectroscopy). The exposure of Ca2+−O2− surface acid‐base pairs allows the dissociation of hydrogen, emphasizing the strong basicity of the related O2− species. Whereas an increasing vanadium content is beneficial to propene selectivity, it scarcely impacts propane conversion. The reaction proceeds mainly upon oxidative dehydrogenation, even if the minor dehydrogenation route is also observed. Surface O2− generated thanks to proton mobility are involved in the C−H bond activation, as shown by the synergistic effect between the oxidative dehydrogenation of propane reaction and the bulk proton conduction measured under operando conditions. This puts emphasis on the key role of strong basic sites for propane activation.
Design of hierarchical, three‐dimensional free‐standing single‐atom electrode for H2O2 production in acidic media
Authors: Zhang Jincheng , Yang Hongbin , Gao Jiajian , Xi Shibo , Cai Weizheng , Zhang Junming , Cui Ping , Liu Bin 
Published: February 2020

AbstractElectrochemical reduction of molecular O2 to hydrogen peroxide (H2O2) offers a promising solution for water purification and environmental remediation. Here, we design a hierarchical free‐standing single‐Co‐atom (with Co–N4 coordination) electrode for oxygen reduction reaction (ORR) via a two‐electron pathway to make H2O2 in acidic media. The current density of the single‐Co‐atom electrode reached 51 mA/cm2 at 0.1 V vs reversible hydrogen electrode, lasting for more than 10 hours of continuous operation with H2O2 selectivity greater than 80%. Toward practical application, the single‐Co‐atom electrode was directly used to assemble an electrochemical cell to produce H2O2 at a rate of 676 mol/kgcat/h with a cell voltage of about 1.6 V.
Synthetic Ellagic Acid Glycosides Inhibit Early Stage Adhesion of Streptococcus agalactiae Biofilms as Observed by Scanning Electron Microscopy
Authors: Chambers Schuyler A. , Gaddy Jennifer A. , Townsend Steven D. 
Published: February 2020

AbstractEllagic acid derivatives possess antimicrobial and antibiofilm properties across a wide‐range of microbial pathogens. Due to their poor solubility and ambident reactivity it is challenging to synthesize, purify, and characterize the activity of ellagic acid glycosides. In this study, we have synthesized three ellagic acid glycoconjugates and evaluated their antimicrobial and antibiofilm activity in Streptococcus agalactiae (Group B Streptococcus, GBS). Their significant impacts on biofilm formation were examined via SEM to reveal early‐stage inhibition of cellular adhesion. Additionally, the synthetic glycosides were evaluated against five of the six ESKAPE pathogens and two fungal pathogens. These studies reveal that the ellagic acid glycosides possess inhibitory effects on the growth of gram‐negative pathogens.
3D‐Structured Monoliths of Nanoporous Polymers by Additive Manufacturing
Authors: Hock Sebastian , Rose Marcus 
Published: February 2020

AbstractRecent advances in 3D printing provide great opportunities for the utilization of functional materials in chemical engineering and heterogeneous catalysis. In this work cylindrical monoliths with varying geometries of transport channels are designed and printed by a fused deposition modeling (FDM) 3D printer from thermoplastic polymers. Their hydrodynamic characteristics are investigated. For a proof of concept composite monoliths of microporous hyper‐crosslinked polymers (HCP) are printed. They contain up to 40 wt % of HCP with an accessible specific surface area of up to 171 m2g−1.
Heterogeneous Photocatalysis in Organic Synthesis
Authors: Gisbertz Sebastian , Pieber Bartholomäus 
Published: February 2020

AbstractVisible light photocatalysis relies mainly on expensive noble metal complexes and organic dyes that are not recyclable. Heterogeneous semiconductors, which are mainly applied for artificial photosynthesis and wastewater treatment, are a promising sustainable alternative and gain increasing attention. Inorganic and organic semiconductors with suitable bandgaps are among the most widely studied heterogeneous photocatalysts due to their high stability and recyclability. More recently, microporous materials, such as conjugated organic polymers, covalent organic frameworks, and metal organic frameworks that can be tuned and designed on a molecular level showed promising results. This review provides an overview of the most common heterogeneous photocatalysts with a focus on their applicability in organic synthesis.
Saltwater intrusion affects nutrient concentrations in soil porewater and surface waters of coastal habitats
Authors: Weissman Danielle S. , Tully Katherine L. 
Published: February 2020

AbstractCoastal ecosystems are undergoing major biogeochemical shifts due to climate change and sea level rise. At the same time, agricultural fertilizer applications are increasing coastal nutrient inputs. In this study, we examine the potential impact of saltwater intrusion (SWI) on nitrogen (N) and phosphorus (P) concentrations in soil porewater and surface water of different habitats within the Chesapeake Bay estuary. Study sites are located along Maryland's Lower Eastern Shore and were monitored over three summers from 2016 to 2018. These sites encompass various habitats on the land–sea interface, consisting of healthy forests, intruded forests, abandoned fields, intruded fields, agricultural ditches, tidal creeks, and tidal salt marshes. Intruded fields were being actively farmed at the time of the study. Soil porewater and surface water grab samples were collected from the habitats and analyzed for electrical conductivity, pH, dissolved organic P (DOP), dissolved inorganic P in the form of soluble reactive P (SRP), dissolved inorganic N as ammonium‐N (NH4‐N), and total dissolved iron (TDFe). Electrical conductivity was greatest in the marshes (16.58 mS/cm averaged across all years) and did not significantly differ among intruded forests, intruded fields, and agricultural ditches. As a legacy of heavy fertilizer use, DOP concentrations exceeded 0.45 mg P/L in all habitats. Concentrations of inorganic N and P differed significantly by habitat. Concentrations of NH4‐N were significantly higher in salt marsh soil porewater than in any other habitat measured. Overall, SRP concentrations were the highest in the soil porewater of intruded fields and marshes and in the surface water of agricultural ditches (0.30, 0.29, and 0.33 mg P/L averaged across all years, respectively). These concentrations greatly exceeded recommended U.S. Environmental Protection Agency nutrient pollution thresholds for the region. In its oxidized state, dissolved iron can bind to SRP and prevent it from becoming bioavailable. However, TDFe concentrations in the ditches, tidal creeks, and marshes were too low to adequately buffer against SRP loss to downstream areas. As SWI moves salts inland and increases hydrologic connectivity across coastal landscapes, it is important to consider the mechanisms through which nutrients may be released from coastal soils and their potential to impact downstream water quality.
Variation in individual reproductive performance amplified with population size in a long‐lived carnivore
Authors: Badger Janelle J. , Bowen W. Don , den Heyer Cornelia E. , Breed Greg A. 
Published: February 2020

AbstractIndividual variation in reproductive ability is a key component of natural selection within populations, driving the evolution of life histories and population responses to changing environmental conditions. Evidence that population density affects individual‐level fitness in wild populations is limited, particularly for long‐lived animals, which are difficult to observe on a biologically relevant scale. We tested for individual heterogeneity in reproductive performance in female grey seals (Halichoerus grypus) using 35 yr of mark–resighting data at Sable Island, Canada (43.93° N 59.91° W). We used Bayesian generalized linear mixed‐effect models and multistate open robust design mark–resight models to investigate whether population size negatively influences individual reproductive performance. We measured reproductive performance in two ways: reproductive frequency (the probability of returning to the island to breed) and annual provisioning performance (the probability of successfully weaning a pup given a female bred). Sighting histories of 1,655 known‐aged females with a total of 22,961 pupping events were used for analysis. After accounting for effects of female age, parity, and random year effects, we found that both provisioning performance and reproductive frequency demonstrated a strong, positive correlation with population size. Among‐individual variance in reproductive traits and responses to population size indicated considerable heterogeneity in overall reproductive performance. As population size grew, “robust” females increased their reproductive performance more than their more “frail” conspecifics in both reproductive traits, resulting in an amplification of differences among individuals. Consequently, simulations from posterior distributions revealed a large fitness consequence of heterogeneity in this population, with “frail” individuals having 47.1% fewer successful pups than more “robust” females (mean reproductive output ± SD: 9.12 ± 3.77 pups for frail individuals, 16.97 ± 2.94 for robust individuals). Repeatability of overall reproductive performance across environments indicates individual quality may be more influential to lifetime reproductive success than costs associated with reproductive investment. This quantification of relative fitness and its dynamics is crucial to understanding broad evolutionary processes in natural populations.
Ag−Co3O4 @ Nr GO Material Synthesized by One‐pot Hydrothermal Method for Carcinoembryonic Antigen (CEA) Detection of Enzyme‐mimetic Electrochemical Immunosensor
Authors: Wu M. , Zhao C. L. , Yang Y. X. , Cao K. H. , Qiao X. W. , Hong C. L. 
Published: February 2020

AbstractA high‐sensitivity carcinoembryonic antigen immunosensor was successfully prepared via a one‐step hydrothermal method, wherein nitrogen‐doped graphene oxide (Nr GO) loaded Ag and Co3O4 nanomaterials were synthesized using ammonia as the nitrogen source. Doping nitrogen atoms into the graphene structure forms a new type of N‐type semiconductor with an increased number of graphene layers and more active sites for bonding with chemicals, thereby providing excellent in biocompatibility and good electrical conductivity. The electrical signal of the sensor is further amplified due to the good catalytic effect of Co3O4 and Ag NPs on H2O2. The signal probe requires neither pretreatment nor acid treatment, and can be easy to loaded with metal‐immobilized antibodies, which greatly simplifies the detection step not shorten the detection time. The sensor has good sensitivity to detecting carcinoembryonic antigen (CEA) and can easily operate, and requires mild reaction conditions. Under optimal experimental conditions, the linear range of the sensor is 0.001–200 ng ⋅ mL−1, the detection limit is 0.18 pg ⋅ mL−1, and the linear correlation coefficient is 0.991, which can be used for CEA determination of the actual sample.
Inflammation‐Induced Long Intergenic Noncoding RNA (LINC00665) Increases Malignancy Through Activating the Double‐Stranded RNA–Activated Protein Kinase/Nuclear Factor Kappa B Pathway in Hepatocellular Carcinoma
Authors: Ding Jie , Zhao Jingjing , Huan Lin , Liu Yizhe , Qiao Yejun , Wang Zhen , Chen Zhiao , Huang Shenglin , Zhao Yingjun , He Xianghuo 
Published: February 2020

Background and Aims
The nuclear factor kappa B (NF‐κB) signaling pathway is important for linking inflammation and tumorigenesis. Here, we characterized an NF‐κB signaling activation–induced long intergenic noncoding (LINC) RNA in hepatocellular carcinoma (HCC), LINC00665, that contributes to the enhanced cell proliferation of HCC cells both in vitro and in vivo.

Approach and Results
LINC00665 physically interacts with the double‐stranded RNA (dsRNA)‐activated protein kinase (PKR), enhances its activation, and maintains its protein stability by blocking ubiquitin/proteasome‐dependent degradation, resulting in a positive feedback regulation of NF‐κB signaling in HCC cells. Notably, patients with HCC and higher LINC00665 have poorer outcomes in the clinic.

Conclusions
Our findings indicate that LINC00665 is involved in the NF‐κB signaling activation in HCC cells and that the inflammatory LINC00665/PKR/NF‐κB loop plays important oncogenic roles in hepatic cancer progression and may be a potential therapeutic target.
The protective effect of EGF‐activated ROS in human corneal epithelial cells by inducing mitochondrial autophagy via activation TRPM2
Authors: Huo Yanan , Chen Wei , Zheng Xiaoxiao , Zhao Jinchuan , Zhang Qi , Hou Yuerou , Cai Ying , Lu Xuemei , Jin Xiuming 
Published: February 2020

AbstractOxidative stress is a major pathogenesis of some ocular surface diseases. Our previous study demonstrated that epidermal growth factor (EGF)‐activated reactive oxygen species (ROS) could protect against human corneal epithelial cell (HCE) injury. In the present study, we aimed to explore the role and mechanisms of oxidative stress and mitochondrial autophagy in HCE cells subjected to scratch injury. CCK‐8 assays, EdU assays, Western blot analysis, wound‐healing assays, and flow cytometry were conducted to determine cell viability, proliferation, protein expression, cell apoptosis, and intracellular ROS levels, respectively. The results showed that EGF could promote damage repair and inhibit cell apoptosis in scratch injured HCE cells by upregulating ROS (**p < .01, ***p < .001). EGF also induced mitochondrial autophagy and alleviated mitochondrial damage. Interestingly, the combination of the mitochondrial autophagy inhibitor and mitochondrial division inhibitor 1 (MDIVI‐1) with EGF could reduce cell proliferation, viability, and the ROS level (*p < .05, **p < .01, ***p < .001). Treatment using the ROS inhibitor N‐acetyl‐
l‐cysteine abrogated the increase in mitochondrial membrane potential after EGF treatment. (*p < .05). Taken together, these findings indicated that EGF plays an important role in HCE damage repair and could activate ROS to protect against HCE injury by inducing mitochondrial autophagy via activation of TRPM2.
High efficiency enzymatic synthesis of triglycerides with varying chain length and degree of unsaturation in a solvent‐free system under vacuum
Authors: Bi Yanlan , Chen Jiali , Liu Taiyu , Yang Guolong , Zhang Lu 
Published: February 2020

AbstractBACKGROUNDTriglycerides with varying chain length and unsaturation degree are now in high demand in the food and pharmaceutical industries. Enzymatic catalyzed synthesis methods are favored over chemical‐based processes in the commercial production of triglycerides. This study found that the application of vacuum can improve the efficiency and productivity of enzymatic synthesis of various triglycerides using Novozym 435 (EC 3.1.1.3), an immobilized lipase B from Candida antarctica. The system was used for esterification of fatty acids varying in chain length, unsaturation degree, and oxidation degree.RESULTSThe vacuum condition was not applicable to short chain fatty acids (C4–C6) due to loss of fatty acids in the reaction. The conversions of C4–C6 saturated fatty acids were low (15–35%) under atmospheric pressure. Under vacuum, high conversions (>95%) and triglyceride yields (approximately 90%) were achieved in the esterification of glycerol with several medium‐chain and long‐chain (C8–C18) saturated fatty acids. Moreover, unsaturation degree of fatty acids also affected the triglyceride yield. The triglyceride contents synthesized from C18:2n‐6 (76.17 ± 0.45%) was significantly lower (P < 0.05) than those from C18:0 (91.59 ± 1.58%) and C18:1n‐9 (90.77 ± 0.85%). Furthermore, fatty acids with a high oxidation degree had negative effect on triglyceride synthesis. This vacuum solvent free system allowed the synthesis enzyme to be reused 11 times without significant decrease in the lipase activity for esterification of fatty acids.CONCLUSIONThe studied vacuum facilitated triglyceride synthesis process provides an economically attractive yet sustainable solution for the production of a wide range of triglyceride products. © 2020 Society of Chemical Industry