bluuebunny/crossref_metadata_2025_split huggingface dataset:
SNAr Reaction Toward the Synthesis of Fluorinated Quinolino[2,3,4‐at]porphyrins
Authors: Thuita Damaris , Guberman‐Pfeffer Matthew J. , Brückner Christian 
Published: January 2021

AbstractAn intramolecular SNAr displacement of one o‐fluorine atom of a meso‐pentafluorophenyl‐substituted porphyrin metal complex by a neighboring β‐amino functionality generated the corresponding meso‐fluorophenyl‐substituted metallo‐quinolino[2,3,4‐at]porphyrins that are not accessible using established quinoline‐annulation methodologies. The Cu(II), Ni(II), and Zn(II) complexes were thus prepared. The parent free base quinolino[2,3,4‐at]porphyrin is accessible only by demetallation of the copper or zinc complexes. A strong through‐space NMR‐spectroscopic coupling between the remaining o‐fluorine atoms on the annulated meso‐aryl group and the β‐hydrogen atom on the adjacent pyrrole moiety provide a clear spectroscopic signature for the annulation. Quinoline‐annulation alters the optical properties significantly. On account of the presence of the β‐amino functionality, all quinoline‐annulated porphyrins show strong halochromic responses with Brønsted acids and bases, the prerequisite for their potential use in chemosensing applications.
Synthesis and Molecular Properties of Partially Fluorinated DNTTs**
Authors: Tripp Matthias W. , Bischof Daniel , Dreher Maximilian , Witte Gregor , Koert Ulrich 
Published: January 2021

Abstract1,2,3,4‐Tetrafluoro‐dinaphthothienothiophene (F4DNTT) and 1,2,3,4,8,9,10,11‐octafluoro‐dinaphthothienothiophene (F8DNTT) were synthesized via bisthiomethyl alkene intermediates which were accessible by McMurry coupling or Wittig olefination of partially fluorinated naphthalene precursors. DFT‐based electronic structure calculations, near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy, and UV/Vis measurements were used for HOMO/LUMO gap determination and to analyze the electronic structures of the partially fluorinated DNTTs. Reduced exciton binding was observed in thin films.
Atroposelective Synthesis of Isoriccardin C through a C−H Activated Heck Type Macrocyclization
Authors: Marx Lisa , Lamberty Daniel , Choppin Sabine , Colobert Françoise , Speicher Andreas 
Published: January 2021

AbstractMacrocyclization is typically the key step in syntheses of cyclophane‐type natural products. Considering compounds with axially chiral biaryl moieties, the control of atroposelectivity is essential for biological activity and is synthetically challenging. Herein we report on atroposelective macrocyclization involving an oxidative Heck type process and enabling the first atropo‐enantiopure synthesis of isoriccardin C. A chiral sulfinyl auxiliary in the ortho‐position of a biaryl axis (still flexible) was used to induce a C−H activated atropodiastereoselective oxidative Heck coupling (>98 % de). The traceless character of the sulfinyl auxiliary enables the introduction of a hydroxy group to give the target molecule with >98 % ee as well.
Is Europe facing an opioid epidemic: What does European monitoring data tell us?
Authors: Seyler Thomas , Giraudon Isabelle , Noor André , Mounteney Jane , Griffiths Paul 
Published: January 2021

AbstractThis paper addresses the question of whether Europe is facing an opioid epidemic and utilizes data from the European monitoring system on opioid use, harms and availability, to help assess the situation. Data sources covering the last decade on overdose deaths, drug treatment entrants and drug‐related emergencies suggest that the health burden associated with opioid use is mostly related to the consumption of heroin – and to a lesser extent diverted opioid substitution treatment medications – and that it is primarily affecting an ageing cohort of vulnerable users, with little evidence of an increase in initiation. While opioid‐related deaths are currently at much lower levels than in the United States, they still represent a large preventable health burden with differences across EU countries. There is also increasing concern related to the high availability of heroin, illicitly produced synthetic opioids and diverted opioid pain medications on the European drugs market. Trends in the latter categories are poorly monitored and we may miss signs of emerging problems. Moreover, the economic recession following the COVID‐19 pandemic has a potential to lead to resurgence in opioid use and harms.SignificanceThis paper looks at data from the European monitoring system to address the question of whether Europe is facing an opioid epidemic. It reviews available health and supply side indicators, considering the limitations of each data source. A summary of the available evidence would suggest that while opioid‐related deaths in Europe represent a large preventable health burden with differences across EU countries, Europe as a whole is not facing an opioid crisis of the size and nature seen in the US.
Application of Precipitation‐based and Nanoparticle‐based Techniques for Fabrication of Potentiometric Sensors for Nano Molar Determination of Chitosan and Polyvinyl Pyrrolidone in Pharmaceutical Formulations and Biological Fluids
Authors: Trabik Yossra A. , Al‐Afify Nourhan KH. , El‐Kosasy Amira M. , Magdy N. 
Published: January 2021

AbstractChitosan (CH) is one of the most abundant biopolymers with multiple applications. Polyvinyl pyrrolidone (PVP) has specific binding and detoxification properties that are of great interest in health care. Hence, it arises a crucial urge to develop economic sensors to analyze CH and PVP in pharmaceutical formulations and biological samples. Two portable sensors were fabricated using precipitation‐based technique, and nanoparticles‐based technique, for determination of CH and PVP in sensor 1 and 2; respectively. Linear responses of 10−5 to10−7 M and 10−2 to10−7 M at pH 3.6–4.8 and 7.2–8.4, with ideal Nernstian slopes of 60.00 and 59.83 mV /decade, and nanomolar LODs of 94.90 and 81.20 nM were observed for CH and PVP; respectively. The percentage recoveries were 100.40±1.03 and 100.19±0.64 for sensors 1 and 2; respectively. Both sensors were successfully applied in biological fluids without pre‐treatment. Accurate results were obtained using sensor 1, in pure form, pharmaceutical formulations, human plasma, rat liver and rat brain, as well as sensor 2, in pure form, pharmaceutical formulations and urine samples. The results were statistically compared with the reported methods and no significant difference was observed.
Advances of capillary electrophoresis enantioseparations in pharmaceutical analysis (2017–2020)
Authors: Krait Sulaiman , Konjaria Mari‐Luiza , Scriba Gerhard K. E. 
Published: January 2021

AbstractCapillary electrophoresis is a powerful technique for the analysis of polar chiral compounds and has been widely accepted for analytical enantioseparations of drug compounds in pharmaceuticals and biological media. In addition, many mechanistic studies have been conducted in an attempt to rationalize enantioseparations in combination with spectroscopic and computational techniques. The present review will focus on recent examples of mechanistic aspects and summarize recent applications of stereoselective pharmaceutical and biomedical analysis published between January 2017 and November 2020. Various separation modes including electrokinetic chromatography in combination with several detection modes including laser‐induced fluorescence, mass spectrometry and contactless conductivity detection will be discussed. A general trend also observed in other analytical techniques is the application of quality by design principles in method development and optimization.
Steel frame with aseismic floor: From the viscoelastic decoupler model to the elastic structural response
Authors: Xiang Yang , Koetaka Yuji , Nishira Kohei 
Published: January 2021

AbstractBy installing laminated viscoelastic materials (LVEM) between floor slabs and steel beams, the lateral motions of the floor and the frame are decoupled and the structural seismic response is mitigated. This paper presents a study of the elastic seismic performance of the steel frame with this floor system (hereafter termed the aseismic floor). First, the dynamic model of an LVEM under the combined precompression (vertical) and shear (lateral) is checked by experiment. The dynamic shearing behavior of the precompressed LVEM could be well simulated by the pure‐shear model (without precompression) using the modified shear area‐to‐thickness ratio. The storage modulus and the loss factor of the precompressed LVEM could be deemed the same as those without precompression. Second, the time‐varying dynamic properties of LVEM during the seismic response history are processed. In the processing, the transient frequency of LVEM is assumed to be equal to the fundamental frequency of the accordant conventional frame, and the dynamic property of the structure equipped with the aseismic floor is assumed stable throughout the response history. The accuracy of the processing is validated via numerical analyses. Third, based on the processed structural dynamic properties, the effectiveness of a complex Complete‐Quadratic‐Combination (CQC) method for predicting the peak structural seismic response is checked. The CQC method is recalibrated to account for the deviation between the pseudo‐ and relative velocities of the modal oscillators. The recalibrated CQC method could well predict the interstory drift of the frame and the shear deformation of the LVEM.
A method for calculating loss of shale gas during coring based on forward modeling
Authors: He Junbo , Tang Jiren , Lu Zhaohui , Wang Lei , Zhou Jiankun , Tang Bowen 
Published: January 2021

AbstractThe loss of shale gas from conventional wells during coring directly affects the accuracy of measurement of shale gas content and the efficient development and utilization of shale gas. The existing methods to determine shale gas loss are not sufficiently accurate. This study used the forward modeling approach with consideration of the main influencing factors [FM (a, b)] to accurately calculate the volume of shale gas loss. Simulations of shale gas loss were run in an independently developed indoor experimental platform. A comparative analysis with established fitting methods showed that shale gas mainly exists in either a free state or an adsorbed state, and a pressure differential between the interior and exterior of the core is the primary cause of shale gas loss during coring. The FM (a, b) model simulations of shale gas loss showed reductions in average error of 16.77% and 4.6% compared to that of the improved US Bureau of Mines Method (USBM) and the curve fitting method, respectively. This study established a novel, highly accurate and widely applicable method of calculating the volume of lost shale gas.
Experimental investigation of the morphodynamic response of riffles and pools to unsteady flow and increased sediment supply
Authors: Morgan Jacob A. , Nelson Peter A. 
Published: January 2021

AbstractGravel‐bed rivers characteristically exhibit shallow riffles in wide sections and deeper pools where the channel becomes constricted and narrow. While rivers can adjust to changing flow and sediment supply through some combination of adjustments of channel slope, bed‐surface sorting, and channel shape, the degree to which riffle‐pools may adopt these changes in response to changing flows and sediment supplies remains unclear. This article presents results from a flume experiment investigating how constant‐ and variable‐width channels adjust their morphology in response to changing flow and increased sediment supply. Two flume geometries were used: (1) constant‐width and (2) variable‐width, characterized by a sinusoidal pattern with a mean width equal to that of the first channel. The variable‐width channel developed bed undulations in phase with the width, representing riffle‐pools. The experiment consisted of three phases for each flume geometry: (1) steady flow, constant sediment supply; (2) unsteady flow, constant sediment supply; and (3) unsteady flow, doubled sediment supply. Unsteady flow was implemented in the form of repeated symmetrical stepped hydrographs, with a mean discharge equal to that in the steady flow phase. In all phases the bed and sediment supply were composed of a sand/gravel mixture ranging from 1 to 8 mm. In both the straight and variable‐width channels, transitioning from steady flow to repeated hydrographs did not result in significant changes in bed morphology. The two channel geometries had different responses to increased sediment supply: the slope of the straight channel increased nearly 40%, while the variable‐width channel reduced the relief between bars and pools and decreased the variability in cross‐sectional elevation with a slight slope increase. Bar‐pool relief varied with repeat discharge hydrographs. Pool elevation changed twice the distance of bar elevations, emphasizing the relevance of pool scour for riffle‐pool self‐maintenance in channels with width variations.
Enhancing physical layer security via a UAV friendly jammer for NOMA‐based IoT systems with imperfect CSI
Authors: Chen Yang , Zhang Zhongpei , Li Binrui 
Published: January 2021

AbstractIn this article, we investigate physical layer security in downlink Internet of Things networks under imperfect channel state information (CSI), in which a controller (Alice) intends to serve two user devices (D1 and D2) simultaneously by using nonorthogonal multiple access (NOMA). Cooperative jamming (CJ) is introduced as a powerful solution for guaranteeing secure transmission. To be specific, we integrate an unmanned aerial vehicle (UAV) jammer that generates artificial noise to confuse multiple noncolluding eavesdroppers (Eves). Considering only D1 requires secure transmission, we develop an adaptive power allocation scheme to maximize the secrecy rate at D1 while meeting the desired quality of service (QoS) threshold at D2. Furthermore, a strategy can be utilized to obtain the optimal location of the UAV jammer is derived for further performance enhancement. Besides, we also examine the impact of the channel uncertainties on system performance. Numerical results are provided to confirm the superiority and applicability of the proposed CJ scheme over benchmark schemes in terms of secrecy performance and effective energy efficiency.
Scenario planning as a strategy process to foster supply chain adaptability: theoretical framework and longitudinal case
Authors: Phadnis Shardul Sharad , Darkow Inga‐Lena 
Published: January 2021

AbstractDespite the decades long use of scenario planning to formulate corporate strategies, its application for making long‐term decisions in operational settings is limited. We present a theoretical model explaining how scenario planning can help address an important and intractable issue in operations and supply chain management (OSCM): supply chain adaptability. The OSCM literature describes what type of flexibility enables supply chain adaptability, but remains largely silent on how the right flexibility is embedded and enacted in supply chains. Building on the attention‐based view, we outline the antecedents and deterrents of supply chain adaptability. We theorize how “excessive focus on operational exploitation” and “operations‐focused cognition” deter supply chain adaptability, and how scenario planning serves as a strategy process to overcome the deterrents. We illustrate the theoretical model with a longitudinal industry–academia collaborative field study that used scenario planning to formulate, implement, and adapt a chemical company's supply chain strategy over 7 years in Asia's dynamic and unpredictable business environment. We hope that this study at the intersection of foresight studies and OSCM encourages scholarly collaboration between these two largely disparate communities, and provides a foundation for future research amid the growing importance of managing supply chains in unpredictable business environments.
Assessing liquidity‐adjusted risk forecasts
Authors: Berger Theo , Uffmann Christina 
Published: January 2021

AbstractIn this paper, we provide a thorough study on the relevance of liquidity‐adjusted value‐at‐risk (LVaR) and expected shortfall (LES) forecasts. We measure additional liquidity of an asset via the difference between its respective bid and ask prices and we assess the non‐normality of bid–ask spreads, especially in turbulent market times. The empirical assessment comprises German stocks in both calm and turmoil market times, and our results provide evidence that liquidity risk turns out to be crucial for the quality of regulatory risk assessment in turmoil market times. We find that a Cornish–Fisher approximation describes a sensible choice for LVaR forecasts whereas an extreme value approach results in adequate LES forecasts.
Do local and global factors impact the emerging markets' sovereign yield curves? Evidence from a data‐rich environment
Authors: Cepni Oguzhan , Guney Ibrahim Ethem , Kucuksarac Doruk , Hasan Yilmaz M. 
Published: January 2021

AbstractThis paper investigates the relation between yield curve and macroeconomic factors for 10 emerging sovereign bond markets using the sample from January 2006 to April 2019. To this end, the diffusion indices obtained under four categories (global variables, inflation, domestic financial variables, and economic activity) are incorporated by estimating dynamic panel data regressions together with the yield curve factors. Besides, in order to capture dynamic interaction between yield curve and macroeconomic/financial factors, a panel vector autoregressive (VAR) analysis based on the system generalized method of moments (GMM) approach is utilized. Empirical results suggest that the level factor responds to shocks originated from inflation, domestic financial variables, and global variables. Furthermore, the slope factor is affected by shocks in global variables, and the curvature factor appears to be influenced by domestic financial variables. We also show that macroeconomic/financial factors captures significant predictive information over yield curve factors by running individual country factor‐augmented predictive regressions and variable selection algorithms such ridge regression, least absolute shrinkage operator (LASSO), and Elastic Net. Our findings have important implications for policymakers and fund managers by explaining the underlying forces of movements in the yield curve and forecasting accurately dynamics of yield curve factors.
Providing new formulation for white compound chocolate based on mixture of soy flour, sesame paste, and emulsifier: An optimization study using response surface methodology
Authors: Hosseini Abdul Fateh , Mazaheri‐Tehrani Mostafa , Yeganehzad Samira , Razavi Seyed Mohammad Ali 
Published: January 2021

AbstractThis study was aimed at evaluating the suitability of sesame paste as an ingredient in white compound chocolate using response surface methodology. A D‐optimal combined mixture‐process design with three mixture components, sesame paste (15%–30% w/w), soy flour (0%–15% w/w), and milk powder (0%–15% w/w) under variable amount of emulsifier was used to optimize textural (hardness, cohesiveness, and adhesive force) and thermal (Tonset and Tm) properties of white compound chocolate containing sesame paste. The results showed that the linear effect of all the mixture components was significant (p < .05) on the responses. Applying a desirability function method, the optimum proportion of mixture components, and emulsifier level were as follows: sesame paste 15.5% w/w, milk powder 7.5% w/w, soy four 7% w/w, and emulsifier 0% w/w, respectively. At optimum point, hardness, cohesiveness, adhesive force, Tonset, and Tm were 367.07 (N), 0.63, 8.46 (N), 28.1 (°C), and 33.7 (°C), respectively. The predicted values were confirmed through validation experiment.
Comprehensive Genomic Investigation of Coevolution of mcr genes in Escherichia coli Strains via Nanopore Sequencing
Authors: Li Ruichao , Du Pengcheng , Zhang Pei , Li Yan , Yang Xiaorong , Wang Zhiqiang , Wang Juan , Bai Li 
Published: January 2021

AbstractHorizontal gene transfer facilitates the spread of antibiotic resistance genes, which constitutes a global challenge. However, the evolutionary trajectory of the mobile colistin resistome in bacteria is largely unknown. To investigate the coevolution and fitness cost of the colistin resistance genes in wild strains, different assays to uncover the genomic dynamics of mcr‐1 and mcr‐3 in bacterial populations are utilized. Escherichia coli strains harboring both mcr‐1 and mcr‐3.1/3.5 are isolated and mcr genes are associated with diverse mobile elements. Under exposure to colistin, the mcr‐1‐bearing resistome is stably inherited during bacterial replication, but mcr‐3 is prone to be eliminated in populations of certain strains. In the absence of colistin, the persistence rates of the mcr‐1 and mcr‐3‐bearing subclones varies depending on the genomic background. The decay of the mcr‐bearing bacterial populations can be mediated by the elimination of mcr‐containing segments, large genomic deletions, and plasmid loss. Mobile elements, including plasmids and transposons, are double‐edged swords in the evolution of the resistome. The findings support the idea that antibiotic overuse accounts for global spread of multidrug‐resistant (MDR) bacteria. Therefore, stringent regulation of antibiotic prescription for humans and animals should be performed systematically to alleviate the threat of MDR bacteria.
Relative sea‐level changes along the Fethiye coast (SW Turkey) based on recent archaeological data
Authors: Kızıldağ Nilhan , Özdaş Harun 
Published: January 2021

AbstractWe investigated three coastal archaeological sites along the coast of Fethiye (south‐western Turkey, eastern Mediterranean) to reveal relative sea‐level changes that have occurred since early Byzantine times. Focusing on this little known period, the most recent archaeological data are presented here, providing new data for the history of sea‐level changes. Current elevations of submerged archaeological remains relative to present sea level were measured, and relative sea‐level change was determined, based on an approximation of the original elevation. The contemporary archaeological structures revealed three different sea levels in adjacent areas. Taking into account the time of the last use of the structures, instead of their time of construction, we suggest a relative sea‐level rise at a minimum rate of 1.6 ± 0.3 mm/year for Şövalye Island, 2.1 ± 0.3 mm/year for Gemiler Island, and 2.2 ± 0.6 mm/year for Ölüdeniz Lagoon for the last 1400 years. A comparison of the study results and geoarchaeological data from nearby sites on the western coasts of Fethiye Gulf revealed the degree of sea‐level change impact upon coastal archaeological sites. Results demonstrate that the seismically active Fethiye coast has been strongly influenced by the vertical tectonic movement since early Byzantine times.