bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic Zippers as an Enabling Tool for Engineering of Non‐Ribosomal Peptide Synthetases**
Authors: Bozhueyuek Kenan A. J. , Watzel Jonas , Abbood Nadya , Bode Helge B. 
Published: May 2021

AbstractNon‐ribosomal peptide synthetases (NRPSs) are the origin of a wide range of natural products, including many clinically used drugs. Efficient engineering of these often giant biosynthetic machineries to produce novel non‐ribosomal peptides (NRPs) is an ongoing challenge. Here we describe a cloning and co‐expression strategy to functionally combine NRPS fragments of Gram‐negative and ‐positive origin, synthesising novel peptides at titres up to 220 mg L−1. Extending from the recently introduced definition of eXchange Units (XUs), we inserted synthetic zippers (SZs) to split single protein NRPSs into independently expressed and translated polypeptide chains. These synthetic type of NRPS (type S) enables easier access to engineering, overcomes cloning limitations, and provides a simple and rapid approach to building peptide libraries via the combination of different NRPS subunits.
Self‐Assembled Peptide Nano‐Superstructure towards Enzyme Mimicking Hydrolysis
Authors: Chen Yu , Yang Yuqin , Orr Asuka A. , Makam Pandeeswar , Redko Boris , Haimov Elvira , Wang Yannan , Shimon Linda J. W. , Rencus‐Lazar Sigal , Ju Meiting , Tamamis Phanourios , Dong Hao , Gazit Ehud 
Published: May 2021

AbstractThe structural arrangement of amino acid residues in native enzymes underlies their remarkable catalytic properties, thus providing a notable point of reference for designing potent yet simple biomimetic catalysts. Herein, we describe a minimalistic approach to construct a dipeptide‐based nano‐superstructure with enzyme‐like activity. The self‐assembled biocatalyst comprises one peptide as a single building block, readily synthesized from histidine. Through coordination with zinc ion, the peptide self‐assembly procedure allows the formation of supramolecular β‐sheet ordered nanocrystals, which can be used as basic units to further construct higher‐order superstructure. As a result, remarkable hydrolysis activity and enduring stability are demonstrated. Our work exemplifies the use of a bioinspired supramolecular assembly approach to develop next‐generation biocatalysts for biotechnological applications.
Isolation of 1,4‐Diarsinine‐1,4‐diide and 1,4‐Diarsinine Derivatives
Authors: Rottschäfer Dennis , Glodde Timo , Neumann Beate , Stammler Hans‐Georg , Andrada Diego M. , Ghadwal Rajendra S. 
Published: May 2021

Abstract1,4‐Diarsinine‐1,4‐diide compound [(ADCPh)As]2 (5) (ADCPh={C(DippN)}2CPh, Dipp=2,6‐iPr2C6H3) with a planar C4As2 ring fused between two 1,3‐imidazole scaffolds has been isolated as a red crystalline solid. Compound 5, formally comprising an 8π‐electron C4As2 ring, is antiaromatic and undergoes 2e‐oxidation with AgOTf to form the 6π‐electron aromatic system [(ADCPh)As]2(OTf)2 (6).
Preparation and characterization of tough and highly resilient nanocomposite hydrogels reinforced by surface‐grafted cellulose nanocrystals
Authors: Li Bengang , Han Yuanfeng , Chen Yurui , Cao Xuzhi , Luo Zhenyang 
Published: May 2021

AbstractDespite many strong and tough hydrogels have been fabricated according to the energy dissipating mechanism, they usually lack high resilience due to the presence of large hysteresis. Herein, poly (N‐vinylpyrrolidone) grafted cellulose nanocrystal (CNC‐g‐PVP) was used as special multifunctional physical crosslinkers to fabricate tough and highly resilient nanocomposite hydrogels. CNC‐g‐PVP with varying loading was incorporated into chemically crosslinked polyacrylamide (PAM) networks by in‐situ radical polymerization to give PAM/CNC‐g‐PVP nanocomposite hydrogels. Robust cooperative hydrogen bonds existed between the surface‐grafted PVP chains and the PAM matrix, which could rupture to dissipate energy upon deformation and recover instantly on the removal of stress. This unique energy dissipating mechanism led to excellent mechanical performance of the hydrogels. Their tensile elastic modulus, toughness, and compressive strength are 1.4–1.8, 2.1–3.0, and 1.44–2.73 times of pure PAM hydrogel, respectively. Moreover, the hydrogels exhibit low hysteresis, high resilience (ca. 97%) under cyclic tensile loading‐unloading and good recovery of hysteresis (ca. 90%) under cyclic compressive loading‐unloading.
Assessment of Melamine in Different Water Samples with ZnO‐doped Co3O4Nanoparticles on a Glassy Carbon Electrode by Differential Pulse Voltammetry
Authors: Rahman Mohammed M. , Alam M. M. , Asiri Abdullah M. , Uddin Jamal 
Published: May 2021

AbstractIn this investigation, a melamine electrochemical sensor has been developed by using wet‐chemically synthesized low‐dimensional aggregated nanoparticles (NPs) of ZnO‐doped Co3O4as sensing substrate that were decorated onto flat glassy carbon electrode (GCE). The characterization of NPs such as UV‐Vis, FTIR, XRD, XPS, EDS, and FESEM was done for detailed investigations in optical, functional, structural, elemental, and morphological analyses. The ZnO‐doped Co3O4NPs decorated GCE was used as a sensing probe to analyze the target chemical melamine in a phosphate buffer at pH 5.7 by applying differential pulse voltammetry (DPV). It exhibited good performances in terms of sensor analytical parameters such as large linear dynamic range (LDR; 0.15–1.35 mM) of melamine detection, high sensitivity (80.6 μA mM−1 cm−2), low limit of detection (LOD; 0.118±0.005 mM), low limit of quantification (LOQ; 0.393 mM), and fast response time (30 s). Besides this, the good reproducibility (in several hours) and repeatability were investigated under identical conditions. Moreover, it was implemented to measure the long‐time stability, electron mobility, less charge‐transfer resistance, and analyzed diffusion‐controlled process for the oxidation reaction of the NPs assembled working GCE electrode, which showed outstanding chemical sensor performances. For validation, real environmental samples were collected from various water sources and investigated successfully with regard to the reliability of the selective melamine detection with prepared NPs coated sensor probe. Therefore, this approach might be introduced as an alternative route in the sensor technology to detect selectively unsafe chemicals by an electrochemical method with nanostructure‐doped materials for the safety of environmental, ecological, healthcare fields in a broad scale.
Mixing Time and Scale‐up Investigation of a Moving‐Baffle Oscillatory Baffled Column
Authors: Sutherland Kayte , Pakzad Leila , Fatehi Pedram 
Published: May 2021

AbstractMixing time and scale‐up behavior were investigated for a moving‐baffle oscillatory baffled column (MB‐OBC). Computational fluid dynamics software was used to investigate the effects of the oscillation conditions and changes in the column scale on the dimensionless mixing time. The results indicate that small amplitudes combined with high frequencies are detrimental to the mixing efficiency and that the scale‐up of an MB‐OBC is linearly dependent on the column diameter. This work, in combination with previous studies, proves that the predictability of the hydrodynamic behavior during scale‐up is inherent to oscillatory baffled columns. This trait is desirable for adapting these columns for industrial‐scale applications.
Extractive and Auto‐Extractive Distillation of Azeotropic Mixtures
Authors: Frolkova Alla , Frolkova Anastasia , Gaganov Ivan 
Published: May 2021

AbstractExtractive distillation is one of the energy‐efficient methods for separating azeotropic mixtures. The question of the influence of the mixture original composition on the operating parameters of the columns of extractive and auto‐extractive distillation remains open. The extractive distillation of an acetone+methanol mixture and auto‐extractive distillation of an acetone+methanol+water (dimethylsulfoxide) mixture was simulated using AspenPlus. The impact of the solvent and acetone content in the original mixture on the operating parameters of the columns was investigated for the first time. It is demonstrated that the presence of an entrainer in the original mixture reduces the amount of solvent needed to separate the mixture, the reflux ratio, and the total energy consumption of the process.
Facile Surface Laser Modification of Nickel Foams for Efficient Water Oxidation Electrocatalysis
Authors: Li Yejun , Cao Youwei , Duan Ran , Qi Weihong , Zhang Yangyang , Xie Haipeng , Tong Yonggang , Gao Xiaohui , Yin Kai , Zhang Gufei , Wei Haigen , He Jun 
Published: May 2021

AbstractDespite the recent efforts and progress on the transition metal‐based electrocatalysts for water splitting, it is still a challenge to fabricate oxygen evolution reaction electrocatalysts with high performance, simultaneously via a simple, facile, and environment‐friendly way. Herein, we report a facile strategy for the fabrication of NiFe oxides‐based micro/nano‐structures on Ni foams via simple femtosecond laser ablation, where the Ni : Fe ratio can be readily tuned by changing the amount of Fe precursors dropped on the Ni foams. The resulted electrocatalysts exhibit excellent oxygen evolution reaction activity with low overpotentials of 221 and 241 mV at 25 and 50 mA cm−2, and good long‐term durability under high current density in alkaline condition, suggesting great potentials for practical applications.
Effects of Monochoria vaginalis density on yield losses, economic thresholds, and gross returns in paddy rice (Oryza sativa L.)
Authors: Zhou Wenwen , Luo Juan , Li Baotong , Tang Limei , Zheng Xianxian , Li Yuqi 
Published: May 2021

AbstractMonochoria vaginalis (Burm. f.) Kunth is an annual weed commonly found in paddy fields. Understanding the effects of M. vaginalis on the yield and economics of paddy rice (Oryza sativa L.) is essential for integrated weed management. Here, a field experiment was conducted over two consecutive years (2017–2018) to determine the effects of different densities of M. vaginalis (0, 1, 4, 8, 12, 16, 20, and 24 plants m–2) on yield losses, economic thresholds, and gross returns in paddy rice. The results showed that a higher density of M. vaginalis exhibited greater inhibitory effects on plant height, tiller number per plant, and adjusted gross returns in both early and late rice. The inhibitory effects on spike number per plant, filled grains per panicle, and 1,000‐kernel weight were also significant, although lesser than those observed on the other yield traits. The economic threshold of M. vaginalis under manual weeding varied from 2.80 to 4.44 plants m–2, whereas the threshold levels under herbicide application ranged between 0.71 and 1.03 plants m–2 in the 2 yr. Averaged across all other factors, the adjusted gross returns decreased by 45.0% with increasing M. vaginalis density from 0 to 24 plants m–2. Taking into account the economic thresholds and gross returns, irrational use of herbicides should be prevented for weed management in paddy fields. This study provides useful data for reducing the use of chemical herbicides, saving the costs of weed management practices, and protecting the environment of farmland ecosystems.
Disentangling the effects of host relatedness and elevation on haemosporidian parasite turnover in a clade of songbirds
Authors: Starkloff Naima C. , Turner Wendy C. , FitzGerald Alyssa M. , Oftedal Michelle C. , Martinsen Ellen S. , Kirchman Jeremy J. 
Published: May 2021

AbstractThe persistence of a parasite species in an ecological community is determined both by its environmental tolerance and host breadth. The relative contribution of these niche characteristics to parasite community structure is challenging to parse because host persistence is also a consequence of extrinsic environmental factors. We investigated haemosporidian parasites (genera Plasmodium, Leucocytozoon, and Haemoproteus) in a clade of avian hosts in eastern North America. Species in this clade of Catharus thrushes occupy specific elevational bands in a non‐phylogenetically determined manner. This allowed us to tease apart the effects of host relatedness and elevation on parasite community structure, diversity, and infection prevalence. We screened blood and tissue samples from 414 adult birds from four mountain ranges in the Appalachian Highlands for blood parasites using a cytochrome‐b‐nested PCR protocol and identified parasite lineages by sequencing. We found an overall infection prevalence of 88.4% and identified a total of 38 parasite lineages including six novel lineages. Parasite community patterns varied by genus. Host relatedness rather than elevational zone predicted the beta turnover and phylobeta turnover of Leucocytozoon parasites, indicating that closely related rather than geographically proximate host species had more similar parasites. This pattern was not seen in Plasmodium parasites because the diversity of this parasite genus varied considerably in the high elevational zones among mountain ranges, that is, a sky‐island effect. Haemoproteus parasites were rare in this study system. Our study suggests that the mechanisms that underlie community structuring vary between haemosporidian genera due to differences in the degree of host sharing among lineages.
Nonlinear survival of imperiled fish informs managed flows in a highly modified river
Authors: Michel Cyril J. , Notch Jeremy J. , Cordoleani Flora , Ammann Arnold J. , Danner Eric M. 
Published: May 2021

AbstractWater is a fundamental resource in freshwater ecosystems, and streamflow plays a pivotal role in driving riverine ecology and biodiversity. Ecologically functional flows, managed hydrographs that are meant to reproduce the primary components of the natural hydrograph, are touted as a potential way forward to restore ecological functions of highly modified rivers, while also balancing human water needs. A major challenge in implementing functional flows will be establishing the shape of the managed hydrograph so as to optimize improvements to the ecosystem given the limited resources. Identifying the shape of the flow–biology relationship is thus critical for determining the environmental consequences of flow regulation. In California's Central Valley, studies have found that increased streamflow can improve survival of imperiled juvenile salmon populations during their oceanward migration. These studies have not explored the potential nonlinearities between flow and survival, giving resource managers the difficult task of designing flows intended to help salmon without clear guidance on flow targets. We used an information theoretic approach to analyze migration survival data from 2436 acoustic‐tagged juvenile Chinook salmon from studies spanning differing water years (2013–2019) to extract actionable information on the flow–survival relationship. This relationship was best described by a step function, with three flow thresholds that we defined as minimum (4259 cfs), historic mean (10,712 cfs), and high (22,872 cfs). Survival varied by flow threshold: 3.0% below minimum, 18.9% between minimum and historic mean, 50.8% between historic mean and high, and 35.3% above high. We used these thresholds to design alternative hydrographs over the same years that included an important component of functional flows: spring pulse flows. We compared predicted cohort migration survival between actual and alternative hydrographs. Managed hydrographs with pulse flows that targeted high survival thresholds were predicted to increase annual cohort migration survival by 55–132% without any additions to the water budget and by 79–330% with a modest addition to the water budget. These quantitative estimates of the biological consequences of different flow thresholds provide resource managers with critical information for designing functional flow regimes that benefit salmon in California's highly constrained water management arena.
Greenhouse gas emissions associated with four types of fertilization for corn crops in a Mediterranean basin
Authors: Abrahão Raphael , Carvalho Monica , Causapé Jesús 
Published: May 2021

AbstractThe environmental impacts associated with the intensification of agricultural practices have become an emerging issue, and new techniques are being developed to satisfy public demands. The application of fertilizers is a crucial step for agriculture practices. Building upon previous studies at a Mediterranean basin, the objective of the research presented herein was to quantify the greenhouse gas emissions associated with four different types of fertilization in the production of corn: traditional (NPK 8–15‐15 and urea), controlled‐release (NPK 8–15‐15, and a combination of urea and encapsulated urea), and two types of fertilization with pig slurry (NPK 8–15‐15, pig slurry and different amounts of urea). The Life Cycle Assessment methodology was employed, with the Ecoinvent database and the IPCC 2013 GWP 100y impact assessment method. The results revealed that traditional fertilization emitted 3251 kg CO2‐eq/ha·year, against 2191 kg CO2‐eq/ha·year for controlled‐release fertilization. Pig slurry fertilization emitted 2160 kg CO2‐eq/ha·year, and its alternative with less urea, only 1030 kg CO2‐eq/ha·year. The utilization of pig slurry solves the issue of its disposal and entails lower costs (commercial fertilizer prices follow the prices of oil and gas). The results demonstrated the potential of controlled‐release fertilization and pig slurry to contribute to climate change mitigation.
A quasi‐experimental study on the effect of health and food safety training intervention on restaurant food handlers during the COVID‐19 pandemic
Authors: Mohammadi‐Nasrabadi Fatemeh , Salmani Yeganeh , Esfarjani Fatemeh 
Published: May 2021

AbstractThe restaurant business has turned into a dynamic and ever‐growing industry. So, food safety must be a priority for these establishments, especially during the COVID‐19 pandemic. The aim of this study was to determine the effect of training intervention on the health and food safety knowledge, attitude, and self‐reported practice (KAP) of restaurant food handlers during the COVID‐19 pandemic. This quasi‐experimental study was conducted on 159 restaurant food handlers in Tehran, Iran. The training intervention was developed based on the latest global guidelines. The KAP of the subjects was measured before and after the training. Fisher's exact test, paired t test, and repeated measures ANOVA were used for statistical analysis. Data analysis was done using the IBM_SPSS software. The total knowledge scores of participants were low (17.6%), moderate (35.2%), and good (47.2%) before training, which were changed to 5% (low), 23.9% (moderate), and 71.1% (good) after training. The total pretraining attitude scores were 0.6, 77.4, 18.2, and 3.8% that were changed to 0% (strongly negative), 49.1% (negative), 33.3% (positive), and 17.6% (strongly positive), respectively. Also, the self‐reported practice scores of the participants before training were 1.3, 56, and 42.7 that were changed to 0% (weak), 26.4% (acceptable), and 73.6% (desirable) after the intervention, respectively. Paired t test results showed a statistically significant increase in all scores. The interaction of training with age and education was statistically significant in increasing the knowledge and attitude scores of the participants by the repeated measures ANOVA. Improving the KAP of food handlers by health and food safety training can improve the status of restaurants and minimize the outbreak of pandemic diseases, including COVID‐19, which is an effective step in community health. Thus, it is an urgent need for policymakers to design an online system of continuous food safety training for food handlers.
Effectiveness of the conditional random‐end trading mechanism on the Korea Exchange: Normal trade and Option Shock
Authors: Eom Kyong S. , Kwon Kyung Y. , Park Jong‐Ho 
Published: May 2021

AbstractOption Shock was a notable 2010 manipulation in Korean stock and derivatives markets. Motivated by Option Shock, we examine the effectiveness of the conditional random‐end (RE) trading mechanism during the opening or closing call auction on the Korea Exchange. We find the conditional RE trading mechanism promotes price stabilization, but with some reservations, and improves price discovery and efficiency at the open, but causes overshooting at the close. We also find it somewhat effective in filtering out spoofing orders, but failed to stabilize the market in the extreme case of Option Shock, which motivated a change to an unconditional RE trading mechanism.
Principles and open questions in functional brain network reconstruction
Authors: Korhonen Onerva , Zanin Massimiliano , Papo David 
Published: May 2021

AbstractGraph theory is now becoming a standard tool in system‐level neuroscience. However, endowing observed brain anatomy and dynamics with a complex network representation involves often covert theoretical assumptions and methodological choices which affect the way networks are reconstructed from experimental data, and ultimately the resulting network properties and their interpretation. Here, we review some fundamental conceptual underpinnings and technical issues associated with brain network reconstruction, and discuss how their mutual influence concurs in clarifying the organization of brain function.
Risk of breast cancer and prediagnostic urinary excretion of bisphenol A, triclosan and parabens: The Multiethnic Cohort Study
Authors: Wu Anna H. , Franke Adrian A. , Wilkens Lynne R. , Tseng Chiuchen , Conroy Shannon M. , Li Yuqing , Sangaramoorthy Meera , Polfus Linda M. , DeRouen Mindy C. , Caberto Christian , Haiman Christopher , Stram Daniel O. , Le Marchand Loïc , Cheng Iona 
Published: May 2021

AbstractExposure to bisphenol A (BPA), triclosan and parabens is widespread but their impact on breast cancer risk remains unclear. This nested case‐control study investigated endocrine‐disrupting chemicals (EDCs) and breast cancer risk within the Multiethnic Cohort (MEC). We measured prediagnostic urinary BPA, triclosan and parabens in 1032 postmenopausal women with breast cancer (48 African American, 77 Latino, 155 Native Hawaiian, 478 Japanese American and 274 White) and 1030 individually matched controls, using a sensitive and validated liquid chromatography mass spectrometry assay. Conditional logistic regression was used to examine risk with these EDCs with adjustment for creatinine and potential confounders. In all women, breast cancer risk was not associated with BPA (Ptrend = 0.53) and was inversely associated with triclosan (ORT3 vs T1 = 0.83, 95% CI: 0.66‐1.04, Ptrend = 0.045) and total parabens (ORT3 vs T1 = 0.77, 95% CI: 0.62‐0.97, Ptrend = 0.03). While risk of hormone receptor positive (HR+) cancer was 20% to 23% lower among women in the upper two tertiles of paraben exposure (Ptrend = 0.02), risk of HR negative (HR−) was reduced 27% but only among those in the upper tertile of exposure. Although risk associations did not differ significantly by ethnicity or by body mass index (BMI), the inverse association with triclosan was observed mainly among overweight/obese women (ORT3 vs T1 = 0.76, 95% CI: 0.56‐1.02, Ptrend = 0.02). In summary, breast cancer risk in a multiethnic population was unrelated to BPA and was weakly inversely associated with triclosan and paraben exposures. Studies with multiple urine samples collected before breast cancer diagnosis are needed to further investigate these EDCs and breast cancer risk.