bluuebunny/crossref_metadata_2025_split huggingface dataset:
The chromatographic behaviour of new double‐labelled oligodeoxynucleotide probes containing azaphthalocyanine dye as a quencher with respect to evaluation of their purity
Authors: Kučera Radim , Sčensná Anna , Miletín Miroslav , Zimčík Petr 
Published: November 2020

AbstractThe influence of experimental conditions on chromatographic behaviour of promising oligodeoxynucleotide double‐labelled molecular probes containing an azaphthalocyanine macrocycle as a perspective dark quencher was studied. A recently introduced new stationary phase based on styrene‐divinylbenzene copolymer was tested. The planar and hydrophobic structure of the azaphthalocyanine is considerably different from those of currently used fluorophores and quenchers. Thus, the most challenging issue was the separation of the double‐labelled probe from its main impurity represented by a mono‐labelled probe, containing only the azaphthalocyanine macrocycle. The absorbance measurement cannot simply determine this impurity, and its presence fundamentally compromises the biological assay. The commonly used gradient elution was not suitable and isocratic conditions seemed to be more appropriate. The azaphthalocyanine moiety influences the properties of the modified oligodeoxynucleotides substantially, and thus their chromatographic behaviour was determined predominantly by this quencher. Acetonitrile was the preferred organic solvent for the analysis of probes containing the azaphthalocyanine quencher and the effect of ion‐pairing reagents was dependent on the probe structure. The temperature seemed to be an effective parameter for fine‐tuning of the separation and mass transfer improvement. Generally, our findings could be helpful in method development for purity evaluation of double‐labelled oligodeoxynucleotide probes and semipreparative methods.
Distributions of eight bioactive components in rat tissues administered Marsdenia tenacissima extract orally detected through UPLC–MS/MS
Authors: Li SiYu , Pei WenHan , Guo Tailin , Zhang Hui 
Published: November 2020

AbstractMarsdenia tenacissima (Roxb.) Wight et Arn. (M. tenacissima) is considered an anticancer medicine in traditional Chinese medicine, which is extensively used in clinical application since it has great therapeutic effects. Currently, although a number of articles have examined M. tenacissima in terms of its pharmacology and quality control, few have investigated the in vivo mechanism of M. tenacissima active ingredients. Previously, we have studied the pharmacokinetics of eight active ingredients after oral administration of M. tenacissima extracts in rat plasma. This study constructed a new scientific ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) approach to simultaneously quantify the contents of tenacissosides B, G, H and I, cryptochlorogenic acid, chlorogenic acid, neochlorogenic acid and caffeic acid in rats orally administered M. tenacissima extract. The proposed approach was successfully used for investigating the distributions of those eight analytes in rat tissues, with digoxin being used as an internal control. The Eclipse Plus C18 RRHD column was used for determination at a column temperature of 30°C. The mobile phase system consisted of acetonitrile and water (supplemented with 0.1% formic acid) under optimal gradient elution conditions. Afterwards, this approach was validated according to the requirements for the analysis of biological samples developed by the US Food and Drug Administration, including precision, accuracy, stability and matrix effects. Based on tissue distribution analysis, those eight analytes showed rapid distribution within all the tested tissues. With regard to organic acid distribution, it followed the order stomach > liver > kidney > small intestine > lung > spleen > heart, whereas the four steroids followed the order stomach > lung > spleen > small intestine > liver > kidney > heart. The present study lays the theoretical foundation for the use and development of M. tenacissima in clinical practice.
Liquid chromatography–mass spectrometry applications for quantification of endogenous sex hormones
Authors: Gravitte Amy , Archibald Timothy , Cobble Allison , Kennard Benjamin , Brown Stacy 
Published: November 2020

AbstractLiquid chromatography, coupled with tandem mass spectrometry, presents a powerful tool for the quantification of the sex steroid hormones 17‐β estradiol, progesterone and testosterone from biological matrices. The importance of accurate quantification with these hormones, even at endogenous levels, has evolved with our understanding of the role these regulators play in human development, fertility and disease risk and manifestation. Routine monitoring of these analytes can be accomplished by immunoassay techniques, which face limitations on specificity and sensitivity, or using gas chromatography–mass spectrometry. LC–MS/MS is growing in capability and acceptance for clinically relevant quantification of sex steroid hormones in biological matrices and is able to overcome many of the limitations of immunoassays. Analyte specificity has improved through the use of novel derivatizing agents, and sensitivity has been refined through the use of high‐resolution chromatography and mass spectrometric technology. This review highlights these innovations, among others, in LC–MS/MS steroid hormone analysis captured in the literature over the last decade.
Clinical outcomes of immune checkpoint blockades and the underlying immune escape mechanisms in squamous and adenocarcinoma NSCLC
Authors: Tian Yaru , Zhai Xiaoyang , Yan Weiwei , Zhu Hui , Yu Jinming 
Published: November 2020

AbstractImmune checkpoint blockades (ICBs) have changed the standard of care of squamous and adenocarcinoma non‐small cell lung cancer (NSCLC). Whereas detailed researches regarding ICBs in the two major histological subtypes are rare. In order to uncover the clinical efficacy differences between squamous and adenocarcinoma NSCLC and better understand the underlying immune‐regulatory mechanisms, we compared the survival benefits of ICBs between the two subtypes by revealing phase 3 randomized trials and attempted to uncover the immune‐regulatory discrepancy. Generally, compared with nonsquamous NSCLC, squamous NSCLC benefited more from ICBs in Keynote 024, CheckMate 026, CheckMate 227 and CheckMate 017 and similar in OAK, but less in Keynote 010 and PACIFIC. We revealed that the tumor mutation burden (TMB) level, the programmed cell death ligand 1 (PD‐L1) expression, tumor infiltrating lymphocytes (TILs) in the tumor microenvironment (TME), chemokines, and oncogenic driver alterations within the two subtypes may contributed to the clinical outcomes of ICBs. We prospected that the combinations of ICBs with chemotherapy, radiation therapy, and antiangiogenic therapy could be promising strategies to re‐immunize the less immunogenic tumors and further enhance the efficacy of ICBs.
Electrochemical Characterization of Nanostructured LiMn2O4 Composite in Lithium‐Ion Hybrid Supercapacitors
Authors: Zheng Xiaowen , Li Shuo , Yang Yuan , Chen Lina , Si Pengchao 
Published: November 2020

AbstractA nanostructured spinel LiMn2O4 and graphene composite fabricated by using a simple one‐step method exhibits excellent electrochemical performance as the cathode for aqueous hybrid supercapacitors. The specific capacitance of commercial LiMn2O4 is enhanced five‐fold with a scan rate that is also enhanced 20 times in 1 M Li2SO4 aqueous electrolyte. In addition, the use of water‐in‐salt electrolyte (5 M LiTFSI) greatly improves the electrochemical performance of the hybrid devices, owing to the larger working window. A high energy density of 202 Wh kg−1 at power densities of 171 W kg−1 and 20 Wh kg−1 at 2571 W kg−1 were obtained in 5 M LiTFSI. This work provides two strategies to achieve high‐performance LiMn2O4‐based cathodes and highly concentrated electrolyte for hybrid supercapacitors in actual applications.
Functionalization of Contacted Carbon Nanotube Forests by Dip Coating for High‐Performance Biocathodes
Authors: Singh Meenakshi , Nolan Hugo , Tabrizian Maryam , Cosnier Serge , Düsberg Georg S. , Holzinger Michael 
Published: November 2020

AbstractThis work focuses on the use of electrically contacted carbon nanotube forests as an electrode material for the bioelectrocatalytic reduction of oxygen to water. The forests are directly grown by chemical vapor deposition on a conductive tantalum layer, which provides enough mechanic stability during several functionalization and enzyme immobilization steps. A pyrene bis‐anthraquinone derivative (pyr‐(AQ)2) was attached via π‐stacking throughout the forest and was used as an anchor molecule for oriented immobilization of laccase. This led to high‐performance biocathodes for oxygen reduction via direct electron transfer with absolute maximum current densities up to 0.84 mA cm−2 at 0.2 V vs Ag/AgCl. The morphological changes during the wet chemical processes were studied by scanning electron microscopy (SEM) revealing cellular patterning of the forest structure. Despite these changes, the forest remained attached and electrically connected to the tantalum layer. The resulting bioelectrodes performed with satisfying stabilities under constant discharge conditions and kept 75 % of its initial performances after one week.
The Effect of the Coordination Environment of Atomically Dispersed Fe and N Co‐doped Carbon Nanosheets on CO2 Electroreduction
Authors: Tuo Jinqin , Zhu Yihua , Jiang Hongliang , Shen Jianhua , Li Chunzhong 
Published: November 2020

AbstractSingle‐atom metal and nitrogen co‐doped carbon catalysts have caused an extensive research boom for electrochemical CO2 reduction reaction (CO2RR). The diversity of metal‐N coordination environment at high temperature limits the accurate study of electrocatalytic active sites. In this work, Fe porphyrin is anchored on a nitrogen‐doped graphene substrate through the coordination between Fe and N atoms to form atomically dispersed Fe and N co‐doped graphene nanosheets. The confinement anchoring effect of the nitrogen‐doped graphene substrate prevents Fe atoms from agglomerating into Fe nanoparticles. Apart from that, the different Fe‐N coordination environments and their catalytic effects on CO2RR are investigated by temperature changes. Electrochemical tests and density functional theory (DFT) calculations indicate that the atomically dispersed saturated Fe‐N coordination catalyst have excellent performance for CO2RR and the Faradaic efficiency towards CO can up to 97 % at a potential of −0.5 V (vs. reversible hydrogen electrode, RHE).
Intercalation‐Induced Reversible Electrochromic Behavior of Two‐Dimensional Ti3C2Tx MXene in Organic Electrolytes
Authors: Li Jianmin , Wang Xuehang , Sun Weiwei , Maleski Kathleen , Shuck Christopher E. , Li Ke , Urbankowski Patrick , Hantanasirisakul Kanit , Wang Xiaofeng , Kent Paul , Wang Hongzhi , Gogotsi Yury 
Published: November 2020

AbstractMXenes, a large family of two‐dimensional materials, have attracted tremendous attention due to their unique physical and chemical properties. Reversible ion intercalation between MXene layers allows modification of the optical, thermal, magnetic, and chemical properties. The electrochemical charge/discharge of MXenes in aqueous electrolytes was reported to lead to reversible electrochromic behavior. In this work, the electrochromic effect of semitransparent Ti3C2Tx MXene film was probed by electrochemical intercalation of Li ions. Correspondingly, a peak shift of 100 nm was observed in the UV‐vis spectrum. By combining in‐situ Raman spectroscopy, in‐situ X‐ray diffraction, and density functional theory calculations, we show that the electrochromic shift is primarily due to the formation of robust O−Li bonds and the emerging bands induced changes of inter‐band excitations. Understanding the mechanism of electrochromic behavior in Ti3C2Tx lays the foundations of designating 2D materials with durable, controllable, and efficient intercalation‐induced electrochromic behaviors.
Stuffed Tridymite Structures: Synthesis, Structure, Second Harmonic Generation, Optical, and Multiferroic Properties
Authors: Bhim Anupam , Sutter Jean‐Pascal , Gopalakrishnan Jagannatha , Natarajan Srinivasan 
Published: November 2020

AbstractThe stuffed tridymite structure Ba(Zn/Co)1−xSi1−xM2xO4 (M=Al3+ and Fe3+) is explored for the possible multiferroic behavior and to develop new inorganic colored materials. The compounds were synthesized by employing conventional solid‐state chemistry methods in the temperature range 1100–1175 °C for 24 h. The powder X‐ray diffraction (PXRD) and Rietveld refinement studies indicate that the compounds stabilize in the P63 space group (no. 173). The refinement results were also rationalized by employing Raman spectroscopic studies. The compounds were found to be second harmonic generation (SHG) active and show weak ferroelectric behavior. The co‐substitution of Co2+ and Fe3+ in the structure gives rise to a weak ferromagnetic behavior to the compound, BaCo0.75Si0.75Fe0.5O4, making it a multiferroic material. The optical studies on the prepared compounds exhibited blue color (Co2+ in Td geometry), purple color (Ni2+ in Td geometry), and simultaneous substitution of Co2+ and Fe3+ gives rise to blue‐green color owing to metal‐to‐metal charge transfer (MMCT) effect.
Rational Design of High‐Relaxivity EuII‐Based Contrast Agents for Magnetic Resonance Imaging of Low‐Oxygen Environments
Authors: Bailey Matthew D. , Jin Guo‐Xia , Carniato Fabio , Botta Mauro , Allen Matthew J. 
Published: November 2020

AbstractMetal‐based contrast agents for magnetic resonance imaging present a promising avenue to image hypoxia. EuII‐based contrast agents have a unique biologically relevant redox couple, EuII/III, that distinguishes this metal for use in hypoxia imaging. To that end, we investigated a strategy to enhance the contrast‐enhancing capabilities of EuII‐based cryptates in magnetic resonance imaging by controlling the rotational dynamics. Two dimetallic, EuII‐containing cryptates were synthesized to test the efficacy of rigid versus flexible coupling strategies. A flexible strategy to dimerization led to a modest (114 %) increase in contrast enhancement per Eu ion (60 MHz, 298 K), but a rigid linking strategy led to an excellent (186 %) increase in contrast enhancement despite this compound′s having the smaller molecular mass of the two dimetallic complexes. We envision the rigid linking strategy to be useful in the future design of potent EuII‐based contrast agents for magnetic resonance imaging.
Energy‐aware decision‐making for dynamic task migration in MEC‐based unmanned aerial vehicle delivery system
Authors: Li Rui , Li Xuejun , Xu Jia , Jiang Frank , Jia Zhaohong , Shao Di , Pan Lei , Liu Xiao 
Published: November 2020

AbstractNowadays, unmanned aerial vehicles (UAVs) are widely used in many smart systems such as smart logistics, smart agriculture, and environmental monitoring systems. However, the limited computing capability and restricted battery lifetime of existing UAVs could significantly impact the quality of service (QoS) of UAV‐based smart systems and the quality of experience (QoE) of end users. Recently, Mobile Edge Computing (MEC) which provisions computing resources close to the mobile end devices has become a promising solution. However, since high‐speed UAV often flies through the signal range of the different edge nodes, the interruption of services in the MEC‐based UAV delivery system is a critical issue. A challenging question is when and how to perform dynamic task migration among the edge nodes to ensure service continuity. In this paper, we investigate the task migration issue for multiple UAVs in the MEC‐based UAV delivery system. Specifically, we propose an energy‐aware decision‐making strategy for the dynamic task migration named GAD to optimize the UAV energy consumption. Given the real‐time system status and QoS constraints, and through a dynamic two‐tier decision‐making mechanism, GAD can efficiently make the task migration decision from four candidate decisions, viz. No Migration, Data Migration Only, Cold Migration, and Live Migration. Experimental results based on a real‐world scenario show that our strategy can well outperform other baseline strategies in various metrics including the flying distances and the energy consumption of UAVs.
Memory allocation anomalies in high‐performance computing applications: A study with numerical simulations
Authors: Gomes Antônio Tadeu A. , Molion Enzo , Souto Roberto P. , Méhaut Jean‐François 
Published: November 2020

SummaryA memory allocation anomaly occurs when the allocation of a set of heap blocks imposes an unnecessary overhead on the execution of an application. This overhead is particularly disturbing for high‐performance computing (HPC) applications running on shared resources—for example, numerical simulations running on clusters or clouds—because it may increase either the execution time of the application (contributing to a reduction on the overall efficiency of the shared resource) or its memory consumption (eventually inhibiting its capacity to handle larger problems). In this article, we propose a method for identifying, locating, characterizing and fixing allocation anomalies, and a tool for developers to apply the method. We experiment our method and tool with a numerical simulator aimed at approximating the solutions to partial differential equations using a finite element method. We show that taming allocation anomalies in this simulator reduces both its execution time and the memory footprint of its processes, irrespective of the specific heap allocator being employed with it. We conclude that the developer of HPC applications can benefit from the method and tool during the software development cycle.
High‐dimensionaldata classification model based on random projection andBagging‐support vector machine
Authors: Sun Yujia , Platoš Jan 
Published: November 2020

AbstractAiming at the long training time when classifying high‐dimensional data, a parallel classification model is proposed based on random projection and Bagging‐support vector machine (SVM) to process high‐dimensional data. The model first uses random projection to project the input data into the low‐dimensional space. Then, we used the Bagging method to construct multiple training data subsets and used SVM to train the training subset in parallel and generate several subclassifiers. Finally, various classifiers vote to determine the category of the test sample. The model has been verified using two standard datasets. The experimental results show that the model can significantly improve the training speed and classification performance of high‐dimensional data with little accuracy loss.
Population data mobility retrieval at territory of Czechia in pandemic COVID‐19 period
Authors: Platos Jan , Kromer Pavel , Voznak Miroslav , Snasel Vaclav 
Published: November 2020

AbstractThis article describes the methodology and the possibilities of collecting operation data in a mobile network provider. First, the architecture and the principles used in the system are described. The precision analysis of the population commuting in the region and during the pandemic and nonpandemic times. Moreover, several ideas about further utilization of the data will be formulated and described. Finally, a graph‐based approach that describes the creation of the community structure between the people and the means of its analysis.
Analysis of the mylohyoid nerve in elderly Japanese cadavers for dental implant surgery
Authors: Koga Shintaro , Sato Iwao , Li Zhong‐Lian , Miyaso Hidenobu , Kawata Shinichi , Itoh Masahiro 
Published: November 2020

AbstractObjectivesInjury to the mandibular nerve (MN) branches may cause pain and irregular occlusal movement during mastication after mandibular dental treatments. Growing evidence indicates that the calcitonin gene‐related peptide (CGRP) plays a key role in the development of peripheral sensitization and the associated enhanced pain, suggesting it may be a sign to ensure a safe and reliable dental implant treatment. Our focus was on the distribution of the MN branches and their communication with the lingual nerve (LN), the localized expression of CGRP, and the identification of a pain area related to the mylohyoid muscle (MM) fascia in the mandibular floor.Material and MethodsIn this study, MM samples from 440 sides of 303 human cadavers aged 61–103 years were examined microscopically and immunohistochemically. These data were further evaluated by the use of principal component analysis.ResultsA complex but weak attachment site was identified for the fascia of the MM. CGRP expression was mainly located in small vessels and was scattered throughout the whole fascia of the MM. Communication between the MN and LN was found in 62.5% (275/440) of the samples. The results from the principal component analysis showed that the positive contributions were from the descending branch in the premolar region (correlation coefficient value R = 0.665), the ascending branch in the molar region (R = 0.709) and the intermediate branch of the digastric branch (R = 0.720) in component 1. In the fascia off the MM, strongly labeled CGRP‐positive cells were also found around the blood vessels and the nerve.ConclusionsThe findings reported in this study indicate that there is a risk of damage when pulling the fascia off the MM at the border of the molar and premolar regions during dental implant surgery.
H2 Activation with Co Nanoparticles Encapsulated in N‐Doped Carbon Nanotubes for Green Synthesis of Benzimidazoles
Authors: Lin Chuncheng , Wan Weihao , Wei Xueting , Chen Jinzhu 
Published: November 2020

AbstractCo nanoparticles (NPs) encapsulated in N‐doped carbon nanotubes (Co@NC900) are systematically investigated as a potential alternative to precious Pt‐group catalysts for hydrogenative heterocyclization reactions. Co@NC900 can efficiently catalyze hydrogenative coupling of 2‐nitroaniline to benzaldehyde for synthesis of 2‐phenyl‐1H‐benzo[d]imidazole with >99 % yield at ambient temperature in one step. The robust Co@NC900 catalyst can be easily recovered by an external magnetic field after the reaction and readily recycled for at least six times without any evident decrease in activity. Kinetic experiments indicate that Co@NC900‐promoted hydrogenation is the rate‐determining step with a total apparent activation energy of 41±1 kJ mol−1. Theoretical investigations further reveal that Co@NC900 can activate both H2 and the nitro group of 2‐nitroaniline. The observed energy barrier for H2 dissociation is only 2.70 eV in the rate‐determining step, owing to the presence of confined Co NPs in Co@NC900. Potential industrial application of the earth‐abundant and non‐noble transition metal catalysts is also explored for green and efficient synthesis of heterocyclic compounds.
Sustainable Catalytic Synthesis of Diethyl Carbonate
Authors: Putro Wahyu S. , Ikeda Akira , Shigeyasu Shinji , Hamura Satoshi , Matsumoto Seiji , Lee Vladimir Ya. , Choi Jun‐Chul , Fukaya Norihisa 
Published: November 2020

AbstractNew sustainable approaches should be developed to overcome equilibrium limitation of dialkyl carbonate synthesis from CO2 and alcohols. Using tetraethyl orthosilicate (TEOS) and CO2 with Zr catalysts, we report the first example of sustainable catalytic synthesis of diethyl carbonate (DEC). The disiloxane byproduct can be reverted to TEOS. Under the same conditions, DEC can be synthesized using a wide range of alkoxysilane substrates by investigating the effects of the number of ethoxy substituent in alkoxysilane substrates, alkyl chain, and unsaturated moiety on the fundamental property of this reaction. Mechanistic insights obtained by kinetic studies, labeling experiments, and spectroscopic investigations reveal that DEC is generated via nucleophilic ethoxylation of a CO2‐inserted Zr catalyst and catalyst regeneration by TEOS. The unprecedented transformation offers a new approach toward a cleaner route for DEC synthesis using recyclable alkoxysilane.