bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion Exchange: The Most Important Chemical Reaction on Earth after Photosynthesis
Authors: Meetei Thounaojam Thomas , Devi Yumnam Bijilaxmi , Chanu Thounaojam Thorny 
Published: May 2020

Ion exchange is the interchange of equivalent amount of ions from the solution with ions which are swarming in a boundary of charged surface in equilibrium. It is developed due to the presence of charge in the soil colloids or layer lattice clay minerals. The source of charge developed in the colloidal surface site of soil is mainly from two processes viz. isomorphous substitution and pH dependent charge. The charge can be positive or negative due to the exchange reaction in the layer lattice. The ion exchange capacity is the sum of cation exchange capacity (CEC) and anion exchange capacity (AEC). It depends on the types of soil and the amount of charge present in the layer lattice colloidal structure. With high negative charge in the lattice surface the CEC increases and with positive charge the AEC. Ions with higher charge have larger affinity to adsorbed more strongly than lower. Ion exchange capacity in soil has the ability to retained more nutrients in the form of cations or anions making available to plant for a long time which improved the fertility of soil. Leaching loss of different nutrients from the soil is reduced by holding different ions. Ion exchange processes have been widely used for heavy metal removal for waste water treatment and water purification because of its high remedial capacity, high removal efficiency and fast kinetic. Due to its applications in agriculture, environmental management, industries, waste water treatment in mining industries, laboratory, nanotechnology, geotechnical and other soil reclamation processes it is considered as the second most important reaction in the globe after photosynthesis.
Role of Clinical Electives on Academic Career: A Cross Sectional Study
Authors: Ali Sajjad , Devi Anjuli , Humera Raja Azhar , Sohail Muhammad Taha , Saher Fizza , Qureshi Jabbar Ahmed 
Published: May 2020

Introduction: Clinical Health Electives are an important part of academic curriculum in medical universities throughout the world. Electives are useful in developing personal and professional growth among students. Hence understanding the importance of electives among medical undergraduates on their academic life is important.
Materials and Methods: A cross-sectional based study was conducted among medical undergraduates in Karachi, Pakistan. A total number of 300 students from 3rd, 4th and 5th year of MBBS were taken as a sample. Consent was taken from the participants and questionnaire was filled from everyone. Study population was selected who did at least one clinical elective in their whole academic period.
Results: According to our analysed results, undergraduate students from both private and public sector medical institutes perceived clinical electives as an advantage to themselves. Majority of the students saw their clinical and academic performances to be on a higher level. This shows that opting for electives regardless of its type (local or international) have proven to be fruitful for the undergraduates’ personal growth and academic career, allowing more scope for understudies to practice and enhance their skills they have only done a limited number of times, which inevitably leads to a steep learning curve.
Conclusion: There was a positive influence of clinical electives observed among the students. Overall the academic and clinical performance of the undergraduates enhanced by opting clinical electives and has positive impact on them.
The Progress and Prospect of Zeolitic Imidazolate Frameworks in Cancer Therapy, Antibacterial Activity, and Biomineralization
Authors: Maleki Aziz , Shahbazi Mohammad‐Ali , Alinezhad Vajiheh , Santos Hélder A. 
Published: May 2020

AbstractThe progressive development of zeolitic imidazolate frameworks (ZIFs), as a subfamily of metal‐organic frameworks (MOFs), and their unique features, including tunable pore size, large surface area, high thermal stability, and biodegradability/biocompatibility, have made them attractive in the field of biomedicine, especially for drug delivery and biomineralization applications. The high porosity of ZIFs gives them the opportunity for encapsulating a high amount of therapeutic drugs, proteins, imaging cargos, or a combination of them to construct advanced multifunctional drug delivery systems (DDSs) with combined therapeutic and imaging capabilities. This review summarizes recent strategies on the design and fabrication of ZIF‐based nansystems and their exploration in the biomedical field. First, recent developments for the adjustment of particle size, functionality, and morphology of ZIFs are discussed, which are important for achieving optimized therapeutic/theranostic nanosystems. Second, recent trends on the application of ZIF nanocarriers for the loading of diverse cargos, including anticancer medicines, antibiotic drugs, enzymes, proteins, photosensitizers, as well as imaging and photothermal agents, are investigated in order to understand how multifunctional DDSs can be designed based on the ZIF nanoparticles to treat different diseases, such as cancer and infection. Finally, prospects on the future research direction and applications of ZIF‐based nanomedicines are discussed.
Can Reconstructed Se‐Deficient Line Defects in Monolayer VSe2 Induce Magnetism?
Authors: Chua Rebekah , Yang Jing , He Xiaoyue , Yu Xiaojiang , Yu Wei , Bussolotti Fabio , Wong Ping Kwan Johnny , Loh Kian Ping , Breese Mark B. H. , Goh Kuan Eng Johnson , Huang Yu Li , Wee Andrew T. S. 
Published: May 2020

AbstractThere have been several recent conflicting reports on the ferromagnetism of clean monolayer VSe2. Herein, the controllable formation of 1D defect line patterns in vanadium diselenide (VSe2) monolayers initiated by thermal annealing is presented. Using scanning tunneling microscopy and q‐plus atomic force microscopy techniques, the 1D line features are determined to be 8‐member‐ring arrays, formed via a Se deficient reconstruction process. The reconstructed VSe2 monolayer with Se‐deficient line defects displays room‐temperature ferromagnetism under X‐ray magnetic circular dichroism and magnetic force microscopy, consistent with the density functional theory calculations. This study possibly resolves the controversy on whether ferromagnetism is intrinsic in monolayer VSe2, and highlights the importance of controlling and understanding the atomic structures of surface defects in 2D crystals, which could play key roles in the material properties and hence potential device applications.
Anode‐Free Full Cells: A Pathway to High‐Energy Density Lithium‐Metal Batteries
Authors: Nanda Sanjay , Gupta Abhay , Manthiram Arumugam 
Published: May 2020

AbstractThe development of high‐energy density batteries is critical to the decarbonization of the transportation and power generation sectors. For any given lithium‐containing cathode system, the anode‐free full cell configuration, which eliminates excess lithium and pairs the fully lithiated cathode with a bare current collector, can deliver the maximum possible energy density. The absence of free lithium metal during cell assembly confers significant practical advantages as well. It is also the ideal framework for developing a thorough understanding of lithium deposition in conjunction with various cathode systems. However, the poor efficiencies of lithium plating and stripping lead to rapid lithium inventory loss and poor cycle life. In the last few years, multiple studies have demonstrated the application of advanced electrolytes, modified current collectors, and optimized formation and cycling parameters to stabilize lithium deposition and improve cycle life (80% capacity retention) to 100 cycles and beyond. This review provides an overview of the various strategies toward sustaining lithium inventory in anode‐free full cells and summarizes the work undertaken in this nascent field. It is expected that further improvement upon these strategies and a combinatorial approach can enable cycle lives far in excess of what has been achieved so far.
A pore network model for calculating pressure drop in packed beds of arbitrary‐shaped particles
Authors: Liu Xinlei , Peng Chong , Bai Hongxin , Zhang Qunfeng , Ye Guanghua , Zhou Xinggui , Yuan Weikang 
Published: May 2020

AbstractA pore network model is built to predict pressure drop in packed beds of arbitrary‐shaped particles, using a method that consists of particle packing by the rigid body technique, pore network construction by the maximal sphere algorithm, and numerical calculation of fluid flow. The pore network model is firstly validated by comparing with experiments, Ergun‐type equations, and particle‐resolved computational fluid dynamics (CFD). The pore network model is as accurate as the particle‐resolved CFD, and is remarkably two to three orders of magnitude less computationally intensive. Then, the pore network model is used to calculate the pressure drops in the beds packed with particles of different shapes and sizes, as well as using different flow media. These calculation results prove the versatility of the pore network model. This work provides an accurate yet efficient pore network model for predicting pressure drop, which should be a powerful tool for designing packed beds.
Metal‐Free N‐Annulation of 3‐Formylchromones with α‐Amino Ketones for the Construction of Diverse N‐Functionalized Pyrroles
Authors: Shrestha Rajeev , Khanal Hari Datta , Yang Won‐Guen , Kim Sung Hong , Shim Jae‐Jin , Lee Yong Rok 
Published: May 2020

AbstractA novel and efficient one‐pot approach for the synthesis of diverse and polyfunctionalized pyrroles by the mild organic base‐promoted N‐annulation of 3‐formylchromones with N‐(2‐oxo‐2‐arylethyl)sulfonamides, N‐(2‐oxo‐2‐phenylethyl)methanesulfonamide, or 1‐phenyl‐2‐(phenylamino)ethan‐1‐ones is described. The reaction proceeds via cascade Knoevenagel condensation/intramolecular Michael addition/ring opening. This protocol provides rapid access to biologically interesting polysubstituted pyrroles bearing N‐arylsulfonyl/N‐methylsulfonyl/N‐aryl moieties or a free N−H group.
Effects of Thermally Induced Roton‐Like Excitation on the Superfluid Density of a Quasi‐2D Dipolar Bose Condensed Gas
Authors: Yavari Heshmatollah , Forouharmanesh Forouzan 
Published: May 2020

AbstractUsing the Green's function approach, the density–density correlation function and the dielectric function in the random‐phase approximation for a quasi‐two‐dimensional (quasi‐2D) dipolar Bose gas are derived. From the pole of the density correlation function, by considering thermally induced roton‐like excitations, the excitation spectrum of the system is calculated. It is shown that the position and depth of the roton minimum of the excitation spectrum are tunable by changing the temperature. To show how the position of the roton minimum influences the phenomenon of superfluidity, the superfluid density of the system is obtained and it is shown that the interplay of the thermal rotonization, contact and dipole–dipole interaction (DDI) can affect the superfluid fraction of a quasi‐2D Bose gas. It is found that contact, DDI interactions, and thermally induced rotons enhance the fluctuations and reduce the superfluid density. In the absence of DDI and thermally induced rotons, the usual T3 dependence of superfluid density in 2D is obtained and the correction T4 term arises from DDI. It is shown that if the roton minimum is close to zero, the thermally induced rotons change the linear temperature dependence of the superfluid fraction, leading to a transition to nontrivial supersolid phase.
Reversible Circular Dichroism Induced by Energy Losses without Changing Chirality of Structure
Authors: Deng Junchen , Wang Tiankun , Ng Sha Shiong , Liu Guangqiao 
Published: May 2020

AbstractTunable circular dichroism (CD) is widely used in biology signal detection and chemical analysis. Researchers usually tune CD by changing the chirality and symmetry of nanostructures either directly or indirectly. Changes to a planar nanostructure's chirality are resisted by its structural reciprocity, which also constrains its CD tuning. However, the distribution of finite non‐radiative (ohmic) losses on a planar nanostructure will not be constrained by the reciprocity of structure. Here, a nanostructure is designed to tune the intensity of energy losses rather than change the chirality and symmetry of the whole structure. The results show that not only are the position and intensity of CD affected, but also the sign of the CD signal changes. These methods and results can help in utilizing the new approach to tune the modes and sign of a CD signal.
Huisgen's 1,3‐Dipolar Cycloadditions to Fulvenes Proceed via Ambimodal [6+4]/[4+2] Transition States
Authors: Liu Fang , Chen Yu , Houk K. N. 
Published: May 2020

AbstractHuisgen's 1960 announcement of the concept of 1,3‐dipolar cycloadditions was published the year before Alder's study of the reaction of diazomethane and dimethylfulvene. The diazomethane reaction was studied again in 1970 by Houk et al. and shown to give a [6+4] adduct. Padwa's nitrile ylide cycloaddition to dimethylfulvene (1978) gave [6+4] and [4+2] adducts. We performed computational studies of these reactions with density functional theory (DFT) and show that they involve ambimodal [6+4]/[4+2] transition states that can lead to either type of cycloadduct from one transition state. We dedicate this paper to the extraordinary life and humanity of Rolf Huisgen, and to the undying influence of his discoveries on chemistry.
A novel DOPO‐containing HTBN endowing waterborne polyurethane with excellent flame retardance and mechanical properties
Authors: Wang Hui , Wang Shuang , Du Xiaosheng , Du Zongliang , Wang Haibo , Cheng Xu 
Published: May 2020

AbstractA novel flame‐retardant DHTBN (hydroxyl‐terminated polybutadiene acrylonitrile modified with DOPO) with phosphorus‐containing pendant groups is synthesized based on addition reaction between the hydroxyl‐terminated polybutadiene acrylonitrile and DOPO, which is followed to prepare flame‐retarded WPU (FR‐WPU). The chemical structures of DHTBN and FR‐WPU are confirmed via 31P NMR, XPS, and FT‐IR. The mechanical properties, thermal stability, and flame retardancy of FR‐WPU are conducted a series of tests. The tensile strength and elongation at break for the FR‐WPU films first increased and then decreased with increasing of DOPO contents. The results show that the incorporation of DHTBN into the WPU backbone slightly reduces the thermal stability of FR‐WPU. However, the incorporation of DHTBN into WPU improves the flame retardancy. The TGA‐FIR and Py‐GC‐MS results indicate the gas phase flame‐retardant effect of DHTBN. Furthermore, the morphology, elemental composition, and content of residual char from the FR‐WPU exhibited condensed‐phase flame‐retardant effects on the WPU films.
Management effectiveness in marine protected areas for conservation of Antillean manatees on the eastern coast of the Yucatan Peninsula, Mexico
Authors: Robles Herrejón Juan Carlos , Morales‐Vela Benjamín , Ortega‐Argueta Alejandro , Pozo Carmen , Olivera‐Gómez León David 
Published: May 2020

Abstract

This study evaluated management effectiveness in three marine protected areas (MPAs) for conservation of the Antillean manatee (Trichechus manatus manatus Linnaeus 1758), located on the eastern coast of the Yucatan Peninsula, Mexico. The MPAs evaluated were the Yum‐Balam Flora and Fauna Reserve, Sian Ka'an Biosphere Reserve, and Chetumal Bay Manatee Sanctuary. The extent of the traditional, popular, and scientific manatee knowledge and research were assessed, as well as the prescribed conservation management actions, relevant stakeholders, and the degree of inclusion of manatee species in the management schemes of these MPAs.
Four general criteria, 12 specific criteria, and 62 indicators were developed. In total, 199 interviews were completed in seven communities of the MPAs in order to determine the perception of the social, economic, and conservation impacts of the manatee and its management.
Although the evaluated MPAs were not wholly comparable among themselves due to their different management categories and schemes, administration, socio‐economic context, and the dynamics and conflicts encountered, a comparison was conducted using standardized criteria and a categorical scale in order to evaluate the level of effectiveness of each MPA.
The MPA with the highest management effectiveness in manatee conservation was found to be the Chetumal Bay, with an effectiveness classed as good (71%), followed by Sian Ka'an with intermediate effectiveness (53%) and Yum‐Balam, also with intermediate effectiveness (43%).
The relationships between the key stakeholders of the three MPAs and economic activities such as fishing and tourism are the factors that most influence the effectiveness of management for manatee conservation.
SuptoxD2.0: A second‐generation engineeredEscherichia colistrain achieving further enhanced levels of recombinant membrane protein production
Authors: Michou Myrsini , Stergios Angelos , Skretas Georgios 
Published: May 2020

AbstractThe bacteriumEscherichia coliis among the most popular hosts for recombinant protein production, including that of membrane proteins (MPs). We have recently generated the specialized MP‐producingE. colistrain SuptoxD, which upon co‐expression of the effector genedjlA, is capable of alleviating two major bottlenecks in bacterial recombinant MP production: it suppresses the toxicity that frequently accompanies the MP‐overexpression process and it markedly increases the cellular accumulation of membrane incorporated and properly folded recombinant MP. Combined, these two positive effects result in dramatically enhanced volumetric yields for various recombinant MPs of both prokaryotic and eukaryotic origin. Based on the observation thatdjlAis found in the genomes of various pathogenic bacteria, the aim of the present work was to investigate (a) whether other naturally occurring DjlA variants can exert the MP toxicity‐suppressing and production‐promoting effects similarly to theE. coliDjlA and (b) if we can identify a DjlA variant whose efficiency surpasses that of theE. coliDjlA of SuptoxD. We report that a quite surprisingly broad variety of homologous DjlA proteins exert beneficial effects on recombinant MP when overexpressed inE. coli. Furthermore, we demonstrate that theSalmonella entericaDjlA is an even more potent enhancer of MP productivity compared with theE. coliDjlA of SuptoxD. Based on this, we constructed a second‐generation SuptoxD strain, termed SuptoxD2.0, whose MP‐production capabilities surpass significantly those of the original SuptoxD, and we anticipate that SuptoxD2.0 will become a broadly utilized expression host for recombinant MP production in bacteria.
Serum metabolomic profiling in patients with Alzheimer disease and amnestic mild cognitive impairment by GC/MS
Authors: Sun Congcong , Gao Meimei , Wang Feifei , Yun Yan , Sun Qianwen , Guo Ruichen , Yan Chuanzhu , Sun Xiulian , Li Yi 
Published: May 2020

AbstractThe aim of this study was to characterize the serum metabolic profiles of patients with Alzheimer’s disease (AD) and amnestic mild cognitive impairment (AMCI) using metabolomics based on gas chromatography–mass spectrometry (GC/MS). Serum samples were collected from patients with AD (n = 30) and AMCI (n = 32), and normal healthy controls (NOR, n = 40). Metabolite profiles were performed with GC/MS in conjunction with multivariate statistical analysis, and possible biomarker metabolites were identified. Thirty‐one kinds of endogenous metabolites could be identified simultaneously. Eleven components were chosen as biomarker metabolites between AD and NOR groups, and these metabolites were closely related to seven biological pathways: arginine and proline metabolism, phenylalanine metabolism, β‐alanine metabolism, primary bile acid synthesis, glutathione metabolism, starch and sucrose metabolism, and steroid hormone biosynthesis. Meanwhile, 10 components were chosen as biomarker metabolites between AMCI and NOR groups and seven biological pathways were closely related: arginine and proline metabolism, phenylalanine metabolism, citrate cycle, alanine, aspartate and glutamate metabolism, taurine and hypotaurine metabolism, starch and sucrose metabolism, and steroid hormone biosynthesis. Our study distinguished serum metabotypes between AD, AMCI and NOR patients successfully. The implementation of this metabolomic strategy may help to develop biochemical insight into the metabolic alterations in AD/AMCI and will be helpful for the further understanding of pathogenesis.
Migration‐ and Proliferation‐Promoting Activities in Human Keratinocytes of Zea mays Flower Absolute and Its Chemical Composition
Authors: Kim Do Yoon , Won Kyung Jong , Hwang Dae Il , Kim Ha Bin , Li Yali , Lee Hwan Myung 
Published: May 2020

AbstractZea mays L. (ZM) has cytotoxic and anti‐inflammatory activities, but its biological activities such as skin regeneration and wound healing in human skin have not been reported. In the present study, we tested the effects of ZM flower (ZMF) absolute on proliferation and migration of human keratinocytes (HaCaTs) and identified its components by using gas chromatography/mass spectrometry (GC/MS) analysis. GC/MS analysis revealed that the ZMF absolute contained 13 constituents, and it increased HaCaT proliferation and migration. The ZMF absolute enhanced the phosphorylation levels of serine/threonine‐specific protein kinase (Akt), p38 mitogen‐activated protein kinase (MAPK), and extracellular signal‐regulated kinase1/2 in HaCaTs. In addition, the absolute induced an increase in sprout outgrowth of HaCaTs. The present study reports for the first time that ZMF absolute may promote skin wound healing and/or skin regeneration by stimulating proliferative and migratory activities in dermal keratinocytes through the Akt/MAPK pathway. Therefore, ZMF absolute may be a promising natural material for the use in skin regeneration and/or wound healing applications.
A Defect‐rich N, P Co‐doped Carbon Foam as Efficient Electrocatalyst toward Oxygen Reduction Reaction
Authors: Yang Maomao , Shu Xinxin , Zhang Jintao 
Published: May 2020

AbstractExplore cost‐effective and efficient carbon‐based electrocatalysts toward oxygen reduction reaction is highly desired to replace high‐cost platinum group metal (PGM) catalysts. Herein we synthesized a N, P co‐doped carbon foam by direct blowing of glucose in the presence of phytic acid (blowing catalyst) and urea (self‐sacrificing template). This template‐free one‐step approach achieved high surface heteroatom content of N (5 at.%) and P (2.33 at.%), large surface area (1026 m2 g−1) and high ID/IG ratio. It was found that the edges‐rich activated carbon scaffold as well as the active N‐sites work synthetically to guarantee its efficient ORR performance with the half‐wave potential of 0.84 VRHE. Besides, the well‐balanced porous structure facilitates its practical application as an air cathode in zinc‐air cell, reaching power density of 145 mW cm−2 at the current density of 169 mA cm−2.
Considerations for Scaling Up the Synthesis of a Glycine‐Based Ionic Demulsifier
Authors: Guzmán‐Lucero Diego , Cerón‐Camacho Ricardo , Ocampo‐Barrera René , Martínez‐Palou Rafael 
Published: May 2020

AbstractThe operating conditions for scaling up the synthesis in semibatch‐type reactors of an ionic‐esterified amino acid salt, namely, 2‐(tetradecyloxy)‐2‐oxoethanaminium methanesulfonate, a demulsifier for breaking crude oil‐in‐water emulsions, were established. The conversion and reaction time were studied at different temperatures on a laboratory scale, and the best conditions for the reaction were found at 90 °C. At different reaction scales up to an industrial reactor, the influence of reaction variables such as temperature, order and rate of reagent addition, and reaction time were studied. This progressive scaling study found the most suitable and safest conditions to carry out the industrial‐level scaling of a high‐performance product for oilfield application.