bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assembly of Dimanganese and Heterometallic Manganese Proteins
Authors: Berggren Gustav , Lundin Daniel , Sjöberg Britt‐Marie 
Published: September 2017

AbstractManganese is an essential trace element in all domains of life, and manganese‐dependent enzymes catalyze a wide range of reactions including hydrolysis, phosphorylation, water oxidation, nucleotide reduction, and protection against oxidative stress. Dinuclear manganese‐containing cofactors are both homonuclear and heteronuclear centers. Due to its rich redox chemistry, manganese is found in a number of redox‐active enzymes, where the oxidation state of the metal ion ranges from MnIIto MnIV. Non‐redox‐active metal sites are found in, for example, sweet potato purple acid phosphatase (MnIIFeIII), concanavalin A (MnIICaII), arginase (MnII2), and prolidase (MnII2). Proteins with redox‐active Mn‐containing dinuclear centers generally belong to the ferritin‐like superfamily. Whereas most members of the superfamily have an Fe2center, Mn‐containing metal sites are found in Mn catalase (Mn2), some RNR β subunits (subclasses Ib and Id have Mn2, and subclass Ic has MnFe), and R2lox (MnFe). In addition, a member of DNA‐binding protein from starved cells (Dps) can form an MnFe center. No manganese chaperones are known and Mn‐dependent enzymes plausibly acquire their metals directly from the intracellular pool of Mn2+, which is balanced via different import and efflux transporter systems:Mn catalase catalyzes the disproportionation of the reactive species hydrogen peroxide by alternating between MnIII2and MnII2in two consecutive reactions, detoxifying two hydrogen peroxide molecules to oxygen and water.RNR subclass Ib β subunit has an oxidized metal center and a tyrosyl radical. It initially binds Mn2+and forms a complex with a specific flavodoxin‐like protein that oxidizes the metal center to a transient MnIV/IIIspecies, which converts to the active MnIII2‐Tyr•cofactor.RNR subclass Ic β subunit has an MnIVFeIIIcofactor. It is formed by O2oxidation of a MnIIFeIIcenter, and the initial transient MnIVFeIVcenter is reduced to the active cofactor via an external electron transfer pathway.RNR subclass Id β subunit is suggested to contain an oxidized Mn2center formed in the absence of a flavodoxin‐like maturase and lacks the tyrosyl radical.R2‐like ligand‐binding oxidase (R2lox) has an MnIIIFeIIIcofactor that is generated from MnIIFeIIby O2oxidation. It is assumed that an MnIVFeIVintermediate generates a valine–tyrosine cross‐link adjacent to the metal site.Despite the apparent simplicity of manganese cofactor assembly, nature has developed a number of different methods to control the metalation of manganese proteins and activate the relatively redox‐inert MnIIion.
Siroheme Assembly and Insertion into Nitrite and Sulfite Reductase
Authors: Stroupe M. Elizabeth , Warren Martin J. 
Published: September 2017

Abstract

The presence and role of siroheme in sulfite and nitrite reductase is reviewed as is the biogenesis of the iron‐containing prosthetic group. As a modified tetrapyrrole, siroheme is synthesized on the uroporphyrinogen III primogenitor template that forms the architectural basis for all family members of this group of compounds. The transformation of uroporphyrinogen III into siroheme requires three steps, involving
S
‐adenosylmethionine‐dependent methylation, macrocyclic ring oxidation, and ferrochelation. Some organisms orchestrate these reactions through three separate enzymes, but others employ multifunctional enzymes that represent protein fusions of the individual enzymes. The requirements for the insertion of siroheme into its cognate enzyme are discussed although little information is available concerning the assembly of the fully functional holoenzyme.
Mussel‐Inspired Polyesters with Aliphatic Pendant Groups Demonstrate the Importance of Hydrophobicity in Underwater Adhesion
Authors: Xu Ying , Liu Qianhui , Narayanan Amal , Jain Dharamdeep , Dhinojwala Ali , Joy Abraham 
Published: September 2017

AbstractRecognizing the potential for synthetic adhesives that can function in wet environments, elements of mussel foot proteins such as L‐3,4‐dihydroxyphenylalanine (DOPA) and phosphoserine have been incorporated into synthetic adhesives. Such adhesives have corroborated the advantage of surface active groups like DOPA, but have not yet demonstrated superior performance in wet or underwater environments, without using organic solvents. What has been conspicuously absent from such designs is the effect of hydrophobic components in the performance of underwater adhesives. Herein it is shown that incorporation of hydrophobic groups in low modulus polyester adhesives provides very high lap‐shear strength and resistance to water penetration. In addition to the excellent performance in wet conditions, the designed adhesive can be applied underwater without any solvent, is biodegradable, and is designed from soybean oil, which is a readily available and renewable resource.
2D‐Layered Carbon/TiO2 Hybrids Derived from Ti3C2MXenes for Photocatalytic Hydrogen Evolution under Visible Light Irradiation
Authors: Yuan Wenyu , Cheng Laifei , Zhang Yani , Wu Heng , Lv Shilin , Chai Liying , Guo Xiaohui , Zheng Lianxi 
Published: September 2017

AbstractTiO2 is a promising photocatalytic material for hydrogen generation. However, the fast recombination of electron–holes restricts the photocatalytic performance of TiO2. Herein, this study demonstrates a 2D‐layered carbon/TiO2 (C/TiO2) architecture via CO2 oxidation of 2D‐Ti3C2, in which the 2D carbon layers provide electron transport channels and improve the hole–electron separation efficiency. Compared to Ti3C2 support, the thickness of derived carbon supports is significantly reduced, which enhances the light intensity arriving at the surface of TiO2. The oxidation parameters are investigated systematically. It is found that high temperature and high CO2 gas flux lead to the formation of crystal TiO2 and the oxidation of carbon layers. The bandgap of 2D‐layered C/TiO2 samples is ranged from 2.83 to 2.89 eV. The 2D‐layered C/TiO2 delivers enhanced photocatalytic activity compared with pure TiO2 catalysts. The optimal photocatalytic hydrogen evolution rate of 2D‐layered C/TiO2 is up to 24.04 µmol h−1, which is about 89 times higher than that of pure TiO2. This research broadens the applications of C/TiO2 hybrids and provides new approach to synthesize novel 2D‐layered materials for photocatalytic applications.
First‐Principles Calculations of Quantum Efficiency for Point Defects in Semiconductors: The Example of Yellow Luminance by GaN: CN+ON and GaN:CN
Authors: Zhang Hai‐Shan , Shi Lin , Yang Xiao‐Bao , Zhao Yu‐Jun , Xu Ke , Wang Lin‐Wang 
Published: September 2017

AbstractPoint defects play an important role in the photoelectrical properties of semiconductor materials, and they can be luminescence centers. However, the relationships among the observed luminescence wavelengths, intensities, and the microscopic processes are in most cases unknown, or depend heavily on parameter fitting. In this work, the light‐emitting quantum efficiencies for point defects using ab initio density functional theory are calculated. The study of radiation recombination for electrons and nonradiation recombination for holes is reported here. The results show that the defect CN transition between “−” and “0” charged levels and the defect CN+ON transition between “0” and “+” charged levels both may be responsible for the yellow luminescence (YL) which is observed in experiment. Moreover, the calculation shows significant thermal quenching of the YL starting at 480 K due to re‐excitation of hole into the valence band from the point defects, which is in relatively good agreement with the experimentally observed value. This work shows that it is possible to use ab initio calculations to understand the microscopic mechanisms and the competitions among different channels for the light emissions caused by defects.
Synthesis of Pyrazine–Thiazole Biheteroaryl Compounds through Base‐Promoted Oxidative Cross‐Dehydrogenative Coupling Reactions
Authors: Shan Yuanyuan , Lai Miao , Li Rui , Wu Zhiyong , Zhao Mingqin 
Published: September 2017

AbstractAn efficient and concise one‐pot protocol for the oxidative cross‐dehydrogenative coupling reaction of pyrazine N‐oxides and 1,3‐azole derivatives has been developed. Commercially available and inexpensive 1,3‐azoles were used as the coupling partners. Various biheteroaryl compounds were obtained in up to 67 % yields. This methodology provides a convinent way to construct the pyrazine–thiazole biheteroaryl moieties. Thermogravimetric analysis indicated that the fracture temperature of one of the biheteroaryl compounds was about 237 °C.
Reforming Australia's Superannuation Tax System and the Age Pension to Improve Work and Savings Incentives
Authors: Ingles David , Stewart Miranda 
Published: September 2017

AbstractAustralia's retirement income system combines private and public provision for old age. Retirees rely on private (but highly regulated) superannuation saving that attracts large tax concessions; a public, means‐tested age pension; home ownership; and other private savings. Despite recent changes intended to make the system fairer and more fiscally sustainable, Australia's retirement income system still lacks coherence, produces inequitable outcomes and creates high effective tax rates on work and saving. This article proposes a more coherent approach to address fairness, reduce the effective tax rates on work and saving and provide adequate earnings replacement rates with greater fiscal sustainability than is delivered in the recent reforms.
Altered task‐related modulation of long‐range connectivity in children with autism
Authors: Pillai Ajay S. , McAuliffe Danielle , Lakshmanan Balaji M. , Mostofsky Stewart H. , Crone Nathan E. , Ewen Joshua B. 
Published: September 2017

Functional connectivity differences between children with autism spectrum disorder (ASD) and typically developing children have been described in multiple datasets. However, few studies examine the task‐related changes in connectivity in disorder‐relevant behavioral paradigms. In this paper, we examined the task‐related changes in functional connectivity using EEG and a movement‐based paradigm that has behavioral relevance to ASD. Resting‐state studies motivated our hypothesis that children with ASD would show a decreased magnitude of functional connectivity during the performance of a motor‐control task. Contrary to our initial hypothesis, however, we observed that task‐related modulation of functional connectivity in children with ASD was in the direction opposite to that of TDs. The task‐related connectivity changes were correlated with clinical symptom scores. Our results suggest that children with ASD may have differences in cortical segregation/integration during the performance of a task, and that part of the differences in connectivity modulation may serve as a compensatory mechanism. Autism Res 2018, 11: 245–257. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.Lay SummaryDecreased connectivity between brain regions is thought to cause the symptoms of autism. Because most of our knowledge comes from data in which children are at rest, we do not know how connectivity changes directly lead to autistic behaviors, such as impaired gestures. When typically developing children produced complex movements, connectivity decreased between brain regions. In children with autism, connectivity increased. It may be that behavior‐related changes in brain connectivity are more important than absolute differences in connectivity in autism.
Randomized clinical trial of laparoscopic ultrasonography before laparoscopic colorectal cancer resection
Authors: Ellebæk S B , Fristrup C W , Hovendal C , Qvist N , Bundgaard L , Salomon S , Støvring J , Mortensen M B 
Published: September 2017

Abstract

Background
Intraoperative ultrasonography during open surgery for colorectal cancer may be useful for the detection of unrecognized liver metastases. Laparoscopic ultrasonography (LUS) for the detection of unrecognized liver metastasis has not been studied in a randomized trial. This RCT tested the hypothesis that LUS would change the TNM stage and treatment strategy.

Methods
Patients with colorectal cancer and no known metastases were randomized (1 : 1) to laparoscopic examination (control or laparoscopy plus LUS) in three Danish centres. Neither participants nor staff were blinded to the group assignment.

Results
Three hundred patients were randomized, 150 in each group. After randomization, 43 patients were excluded, leaving 128 in the control group and 129 in the LUS group. Intraoperative T and N categories were not altered by LUS, but laparoscopy alone identified previously undetected M1 disease in one patient (0·8 per cent) in the control group and three (2·3 per cent) in the LUS group. In the latter group, LUS suggested that an additional six patients (4·7 per cent) had M1 disease with liver (4) or para-aortal lymph node (2) metastases. The change in treatment strategy was greater in the LUS than in the control group (7·8 (95 per cent c.i. 3·8 to 13·8) and 0·8 (0 to 4·2) per cent respectively; P = 0·010), but the suspected M1 disease was benign in half of the patients.

Conclusion
Routine LUS during resection of colorectal cancer is not recommended. Registration number: NCT02079389 (http://www.clinicaltrials.gov).
Synergistic Hepatoprotective and Antioxidant Effect of Artichoke, Fig, Blackberry Herbal Mixture on HepG2 Cells and Their Metabolic Profiling Using NMR Coupled with Chemometrics
Authors: Youssef Fadia S. , Labib Rola M. , Eldahshan Omayma A. , Singab Abdel Nasser B. 
Published: September 2017

The edible plants have long been reported to possess a lot of biological activities. Herein, the hepatoprotective and the antioxidant activities of the aqueous infusion of the edible parts of Cynara cardunculus, Ficus carica, and Morus nigra and their herbal mixture (CFM) was investigated in vitro using CCl4 induced damage in HepG2 cells. The highest amelioration was observed via the consumption of CFM at 1 mg/ml showing 47.00% and 37.09% decline in aspartate transaminase and alanine transaminase and 77.32% and 101.02% increase in reduced glutathione and superoxide dismutase comparable to CCl4 treated cells. Metabolic profiling of their aqueous infusions was done using nuclear magnetic resonance spectroscopic experiments coupled with chemometrics particularly hierarchical cluster analysis (HCA) and principal component analysis (PCA). The structural closeness of the various metabolites existing in black berry and the mixture as reflected in the PCA score plot and HCA processed from the 1H‐NMR spectral data could eventually explained the close values in their biological behavior. For fig and artichoke, the existence of different phenolic metabolites that act synergistically could greatly interpret their potent biological behavior. Thus, it can be concluded that a herbal mixture composed of black berry, artichoke, and fig could afford an excellent natural candidate to combat oxidative stress and counteract hepatic toxins owing to its phenolic compounds.
Application of Pulse Radiolysis to Mechanistic Investigations of Catalysis Relevant to Artificial Photosynthesis
Authors: Grills David C. , Polyansky Dmitry E. , Fujita Etsuko 
Published: September 2017

AbstractTaking inspiration from natural photosystems, the goal of artificial photosynthesis is to harness solar energy to convert abundant materials, such as CO2 and H2O, into solar fuels. Catalysts are required to ensure that the necessary redox half‐reactions proceed in the most energy‐efficient manner. It is therefore critical to gain a detailed mechanistic understanding of these catalytic reactions to develop new and improved catalysts. Many of the key catalytic intermediates are short‐lived transient species, requiring time‐resolved spectroscopic techniques for their observation. The two main methods for rapidly generating such species on the sub‐microsecond timescale are laser flash photolysis and pulse radiolysis. These methods complement one another, and both provide important spectroscopic and kinetic information. However, pulse radiolysis proves to be superior in systems with significant spectroscopic overlap between the photosensitizer and other species present during the reaction. Herein, the pulse radiolysis technique and how it has been applied to mechanistic investigations of halfreactions relevant to artificial photosynthesis are reviewed.
Biodiversity maintenance may be lower under partial niche differentiation than under neutrality
Authors: D'Andrea Rafael , Ostling Annette 
Published: September 2017

AbstractNiche differentiation is normally regarded as a key promoter of species coexistence in competitive systems. One might therefore expect that relative to neutral assemblages, niche‐differentiated communities should support more species with longer persistence and lower probability of extinction. Here we compare stochastic niche and neutral dynamics in simulated assemblages, and find that when local dynamics combine with immigration from a regional pool, the effect of niches can be more complex. Trait variation that lessens competition between species will not necessarily give all immigrating species their own niche to occupy. Such partial niche differentiation protects certain species from local extinction, but precipitates exclusion of others. Differences in regional abundances and intrinsic growth rates have similar impacts on persistence times as niche differentiation, and therefore blur the distinction between niche and neutral dynamical patterns—although niche dynamics will influence which species persist longer. Ultimately, unless the number of niches available to species is sufficiently high, niches may actually heighten extinction rates and lower species richness and local persistence times. Our results help make sense of recent observations of community dynamics, and point to the dynamical observations needed to discern the influence of niche differentiation.
Electrochemical Interpretation of Propagation of the Change in the Membrane Potential Using the Goldman‐Hodgkin‐Katz Equation
Authors: Shirai O. , Kitazumi Y. , Kano K. 
Published: September 2017

AbstractNerve conduction has been frequently explained by the Hodgkin‐Huxley equation based on the flow of K+ and Na+ across the cell membrane. By considering the relation between the membrane potential and the membrane current based on the Goldman‐Hodgkin‐Katz equation, it becomes clear that the conventional analysis using the voltage‐clamp method is not correct and that the hyperpolarization condition is artificially made. Taking into account the channel functions and the electronic properties, we suggested a new propagation mechanism. When the nerve cell is excited by an external stimulus, the ligand‐gated channels at the synapse serve as an electric power source to propagate the change in the membrane potential to the synapse terminal along the axon and the voltage‐gated channels at the axon locally assist the directional propagation along the axon.
Optimization of extrusion conditions for the production of instant grain amaranth‐based porridge flour
Authors: Akande Olamide A. , Nakimbugwe Dorothy , Mukisa Ivan M. 
Published: September 2017

AbstractMalnutrition is one of the foremost causes of death among children below 5 years in developing countries. Development of nutrient‐dense food formulations using locally available crops has been proposed as a means to combat this menace. This study optimized the extrusion process for the production of a nutritious amaranth‐based porridge flour. Least cost formulations containing grain amaranth, groundnut, iron‐rich beans, pumpkin, orange‐fleshed sweet potato, carrot, and maize were developed and evaluated by a sensory panel (n = 30) for acceptability using the 9‐point hedonic scale. Extrusion process of the most acceptable porridge flour was optimized by response surface methodology (RSM). Barrel temperature (130–170°C) and feed moisture content (14%–20%) were the independent variables which significantly (p < .05) affected in vitro protein digestibility, vitamin A retention, total polyphenol, phytic content, and iron and zinc extractabilities. Optimization of the extrusion process improved the nutritional quality of the instant flour.
Screening of glycoside hydrolases and ionic liquids for fibre modification
Authors: Rahikainen Jenni , Anbarasan Sasikala , Wahlström Ronny , Parviainen Arno , King Alistair WT , Puranen Terhi , Kruus Kristiina , Kilpeläinen Ilkka , Turunen Ossi , Suurnäkki Anna 
Published: September 2017

AbstractBACKGROUNDThis study elaborates the possibility to apply combined ionic liquid (IL) and enzyme treatments for pulp fibre modification. The approach involves swelling of fibre surfaces with IL followed by enzymatic modification of the disrupted fibre surface using carbohydrate active enzymes.RESULTSThe capacity of seven cellulose‐dissolving or cellulose‐swelling ionic liquids to swell pulp fibres was compared. In addition, thirteen cellulases and five xylanases were screened for their IL tolerance, which determines their applicability in combined or sequential IL–enzyme treatments of fibres. Among the studied ionic liquids, 1‐ethyl‐3‐methylimidazolium dimethylphosphate ([EMIM]DMP) and 1,3‐dimethylimidazolium dimethylphosphate ([DMIM]DMP) had the strongest effect on fibre swelling. These solvents were also found to be the least inactivating for the studied enzymes.CONCLUSIONEnzyme compatibility and cellulose‐dissolving capability are not two conflicting properties of an ionic liquid. © 2017 Society of Chemical Industry
Nitrification is the key process determining N use efficiency in paddy soils
Authors: Wang Jing , Zhao Ying , Zhang Jinbo , Zhao Wei , Müller Christoph , Cai Zucong 
Published: September 2017

AbstractNitrogen (N) fertilizer use efficiency (NUE) in flooded paddy fields is relatively low. Many N fertilizer management options have been proposed to enhance NUE and minimize environmental damage. However, few investigations are focusing on the role of the characteristics of soil N transformations in regulating NUE and N losses in paddy fields. In this study, we test the role of soil N transformations on NUE and N losses under rice growth conditions in two paddy soils collected from Jiangxi (JX) and Sichuan (SC) in China. The N recoveries of applied15N either as nitrate or ammonium in plant and soil, and N losses estimated by15N balance were investigated in rice pot experiments using a15N tracing technique. The results showed that gross nitrification rates in soil collected from JX were much lower than those in soils collected from SC either at 60% water holding capacity (WHC) or rice growth (flooding) conditions, which could be due to the difference in soil pH. The‐N concentration in soil solution was maintained at a relatively high level for a long time period after N fertilizer application in the JX soil (41 d) compared to the SC soil (26 d), caused by different nitrification rates owing to different soil pH. The15N uptake by rice in the JX soil (29–78%) was always significantly higher than that in the SC soil (22–54%), while N losses from the plant–soil system in the JX soil (17–21%) were always significantly lower than those from the SC soil (20–34%) at the same rice growth stage in the labeled15N ammonium treatment. However, there were no significant differences in15N uptake by rice and N losses in appliedtreatment between the two studied soils. These results indicate that nitrification, not denitrification, was the key process determining NUE and N losses in paddy soils. The results of the N application gradient experiment also indicated that higher amounts of N fertilizer should be applied for the same amount of N uptake, however, this caused higher N losses, in soils characterized by high nitrification rate (e.g., the alkaline soil). Results highlighted that soil N transformations in particular nitrification rate provided a very good guideline for an optimized N management.