bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromatographic determination of sulfasalazine and its active metabolites: greenness assessment and application to spiked human plasma
Authors: Abdelrahman Maha M. , Habib Neven M. , Emam Aml A. , Mahmoud Hamada M. , Abdelwhab Nada S. 
Published: February 2020

AbstractGreen TLC‐densitometric and RP‐HPLC methods were developed and validated for the determination of the active prodrug sulfasalazine (SZ), its active metabolite mesalazine (MZ) and the major active metabolite of mesalazine, N‐acetyl‐5‐aminosalicylic acid (AS). In the developed TLC‐densitometric method, chromatographic separation was carried out on TLC silica gel plates 60 F254 using a developing system consisting of ethyl acetate–methanol–ammonia solution 33% (8:2.5:0.3, by volume) and then scanning the separated bands at 215 nm using hydrochlorothiazide as an internal standard with linearity ranges of 0.4–3, 0.4–2.4 and 0.3–2 for SZ, MZ and AS, respectively. The developed RP‐HPLC method depended on chromatographic separation using a C18 column with a solvent mixture of methanol–aqueous acetic acid solution (pH 5) as a mobile phase with gradient elution mode and UV scanning at 243 nm using pyrazinamide as internal standard with linearity ranges of 5–50, 5–40, and 3–20 for SZ, MZ and AS, respectively. US Food and Drug Administration guidelines were followed during validation of the methods. The greenness of the developed methods was estimated using the greenness profile and the Eco‐Scale approach. Both methods passed the four quadrants of the greenness profile and had Eco‐Scale score ˃75, thus they were considered to be green according to these approaches.
Characterization of three‐dimensional rat central nervous system culture maturation, with applications to monitor cholinergic integrity
Authors: Andersen Parker L. , Vermette Patrick , Khalil Abdelouahed , Witkowski Jacek M. , Fülöp Tamas 
Published: February 2020

AbstractStudying age‐related neuropathologies in vitro requires a three‐dimensional (3D) culture system presenting mature phenotypes. In this study, we aimed to determine whether aged reaggregate cultures physiologically represent mature brain tissue. Results support that embryo‐derived rat central nervous system (CNS) reaggregate cultures develop into mature‐like tissues, comparable to in vivo maturation, including the following characteristics: (a) progressive reduction in cell proliferation (reduced anti‐Ki‐67 immunoreactivity), (b) progressive restriction of long neurite growth potential (as explant cultures), and (c) increased and sustained synaptic enzyme (acetylcholine esterase, AChE) activity. The acquisition of mature‐like reaggregate cultures has allowed us to pursue the hypothesis that the physiological integrity of 3D CNS cultures may be monitored by synaptic enzyme activity. To assess this hypothesis, mature‐like reaggregates were exposed to H2O2, glutamate, or amyloid β(1–42); each resulted in diminished AChE activity. H2O2 exposure resulted in nuclear fragmentation. Glutamate and amyloid β(1–42) exposure resulted in acetylcholine content reduction. Simultaneous reduction of AChE activity and acetylcholine content verified diminished cholinergic integrity. This scheme exploiting synapse enzyme activity of mature‐like 3D CNS tissue is therefore applicable to age‐related neuropathology research including in vitro screening of conditions potentially affecting synapse integrity, including the promotion of dementia.
Variations of the celiac trunk investigated by multidetector computed tomography: Systematic review and meta‐analysis with clinical correlations
Authors: Whitley Adam , Oliverius Martin , Kocián Petr , Havlůj Lukáš , Gürlich Robert , Kachlík David 
Published: February 2020

AbstractIn recent years multidetector computed tomography (MDCT) has been used to investigate vascular anatomy for scientific and diagnostic purposes. These studies allow for much larger sample sizes than traditional cadaveric studies. The aim of this research was to perform a systematic review and meta‐analysis on studies investigating the variations of the celiac trunk using MDCT. Major medical databases were used to find studies investigating celiac trunk anatomy using MDCT. Extracted information included demographic details, number of normal celiac trunks, and number of each variant celiac trunk. Using a random effects meta‐analysis the pooled prevalence of each variation was calculated. A total of 36 studies from 14 countries and four continents were included in the meta‐analysis. The total number of subjects included was 17,391. The total prevalence of variant celiac trunks was 10.85%. The different types of celiac trunk variations with their prevalences were: gastrosplenic trunk (3.46%), hepatosplenic trunk (3.88%), hepatogastric trunk (0.24%), absent celiac trunk (0.28%), celiacomesenteric trunk (0.46%), hepatosplenomesenteric trunk (0.26%), gastrosplenomesenteric trunk (0.07%), and celiacomesenteric anastomosis (0.09%). A total of 61 cases (0.19%) were either not described or not described adequately to be included in our classification. Major variations of the celiac trunk are not uncommon and should be anticipated before radiological and surgical interventions. Knowledge of celiac trunk anatomy is important in hepatopancreatobiliary surgery, transplantology, and interventional radiology.
Teaching spread spectrum in the course Telecommunication Systems using Octave
Authors: Čisar Petar , Odry Peter , Maravić Čisar Sanja , Stankov Gordana 
Published: February 2020

AbstractSpread spectrum is a technique used for transmitting telecommunications signals. This topic is relatively complex and can be challenging for students. Thus, programming language Octave has been introduced in the course curriculum of Telecommunication Systems as one of the powerful tools that aid in student understanding of the spread‐spectrum principles. The purpose of this paper is to elaborate on the teaching method of spread‐spectrum technique and its application in telecommunications, with the aim to make this topic understandable to students. The participants of the experiment were fifth‐semester electrical engineering students (N = 86) at a college of applied sciences. To test the previous knowledge of students needed to understand the theory of spread spectrum, a pretest was carried out which refers to general terms from the fundamentals of telecommunications. With the aim to deeper apprehend the necessary theory from this area, the students had to solve examples from engineering practice using open source software Octave, as well as computational tasks, regarding both methods in spread‐spectrum technology. It has been shown that thanks to the visualization of appropriate material, students of the experimental group understood in more detail the method of generating spread‐spectrum signals and the influence of individual parameters on partial signals, in relation to students who did not have the opportunity to use Octave. The results of the research lead us to conclude that software like Octave should be included in courses like Telecommunication Systems as a supplement to the traditional teaching and learning methods.
Mesenchymal stromal cell‐derived extracellular vesicles as cell‐free biologics for the ex vivo expansion of hematopoietic stem cells
Authors: Budgude Pallavi , Kale Vaijayanti , Vaidya Anuradha 
Published: February 2020

AbstractHematopoietic stem cell transplantation (HSCT) is the ultimate choice of treatment for patients with hematological diseases and cancer. The success of HSCT is critically dependent on the number and engraftment efficiency of the transplanted donor hematopoietic stem cells (HSCs). Various studies show that bone marrow‐derived mesenchymal stromal cells (MSCs) support hematopoiesis and also promote ex vivo expansion of HSCs. MSCs exert their therapeutic effect through paracrine activity, partially mediated through extracellular vesicles (EVs). Although the physiological function of EVs is not fully understood, inspiring findings indicate that MSC‐derived EVs can reiterate the hematopoiesis, supporting the ability of MSCs by transferring their cargo containing proteins, lipids, and nucleic acids to the HSCs. The activation state of the MSCs or the signaling mechanism that prevails in them also defines the composition of their EVs, thereby influencing the fate of HSCs. Modulating or preconditioning MSCs to achieve a specific composition of the EV cargo for the ex vivo expansion of HSCs is, therefore, a promising strategy that can overcome several challenges associated with the use of naïve/unprimed MSCs. This review aims to speculate upon the potential role of preconditioned/primed MSC‐derived EVs as “cell‐free biologics,” as a novel strategy for expanding HSCs in vitro.
Construction of α,α‐disubstituted α‐Amino Acid Derivatives via aza‐Morita‐Baylis‐Hillman Reactions of 2‐Aminoacrylates with Activated Olefins
Authors: Gui Hou‐Ze , Jangra Harish , Mao Ben , Wang Tian‐Yu , Yi Heng , Xu Qin , Wei Yin , Zipse Hendrik , Shi Min 
Published: February 2020

AbstractA useful and convenient strategy for the synthesis of α,α‐disubstituted α‐amino acid (α‐AA) derivatives via aza‐Morita‐Baylis‐Hillman reaction of 2‐aminoacrylates with activated olefins has been developed. A variety of α‐AA derivatives containing an α‐amino tertiary center were synthesized in good to excellent yields. The kinetic profiles and calculated methyl anion affinity (MAA) values were employed to rationalize the reactivities of different Michael acceptors used in the reaction.
Efficient One‐Pot Synthesis of Higher Alcohols from Syngas Catalyzed by Iron Nitrides
Authors: Li Linge , Qing Ming , Liu Xingwu , Wang Hong , Liu Suyao , Zhang Yu , Wan Hongliu , Wen Xiaodong , Yang Yong , Li Yongwang 
Published: February 2020

AbstractEfficient synthesis of higher alcohols from syngas over a single‐metal catalyst remains challenging because both active sites for CO dissociation and molecular CO adsorption are required. We report herein that iron nitrides can directly catalyze syngas to higher alcohols with high selectivity. Three iron nitride catalysts (Fe2N, Fe3N, and Fe4N) were fabricated via the nitriding of α‐Fe and their structures were confirmed by X‐ray diffraction (XRD) and Mössbauer spectroscopy (MES). Moreover, no carbides were detected even after syngas conversion for Fe2N and Fe3N catalysts, in which the N content was higher than that in Fe4N (iron nitrides transformed to Fe2C partly). The catalytic performance indicated that higher alcohols could be directly produced from syngas with remarkable selectivity (>51 % for C2+OH selectivity in total alcohols) over iron nitrides, which was tentatively ascribed to the unique electronic structure of iron nitrides, as evidenced by DFT calculation. This study proposed a novel method for the selective one‐step synthesis of higher alcohols from syngas.
Evaluation of a Microreactor for Flow Biocatalysis by Combined Theory and Experiment
Authors: Burgahn Teresa , Pietrek Philip , Dittmeyer Roland , Rabe Kersten S. , Niemeyer Christof M. 
Published: February 2020

AbstractThe operation of enzyme cascades in microfluidic devices is a current field of research that promises manifold applications in biocatalysis. For an optimization of flow biocatalysis systems it is desirable to model the reactor in silico in order to enable a better understanding and thus an economic optimization of the reaction systems. However, due to their high complexity, it is still difficult to simulate coupled enzyme reactions. We here describe a new model for a plug flow reactor consisting of a porous bed of compact uniform particles functionalized with an immobilized ketoreductase (Gre2) which is overflown by a mobile phase containing the enzymatic NADPH cofactor regeneration system based on glucose dehydrogenase (GDH). By studying different flow rates, lengths and layer thicknesses of the catalytic bed, we show that the synergy of experiment and mathematical modeling can optimize the space‐time yields of the reaction system.
On the avoidance of crossing of singular values in the evolving factor analysis
Authors: Neymeyr Klaus , Sawall Mathias , Rasouli Zahra , Maeder Marcel 
Published: February 2020

AbstractEvolving factor analysis (EFA) investigates the evolution of the singular values of matrices formed by a series of measured spectra, typically, resulting from the spectral observation of an ongoing chemical process. In the original EFA, the logarithms of the singular values are plotted for submatrices that include an increasing number of spectra. A typical observation in these plots is that pairs of trajectories of the singular values are on a collision course, but finally, the curves seem to repel each other and then run in different directions. For parameter‐dependent square matrices, such a behaviour is known for the eigenvalues under the keyword of an avoidance of crossing. Here, we adjust the explanation of this avoidance of crossing to the curves of singular values of EFA. Further, a condition is studied that breaks this avoidance of crossing. We demonstrate that the understanding of this noncrossing allows us to design model data sets with a predictable crossing behaviour.
Enhanced Operational Durability of Thermally Activated Delayed Fluorescence‐Based Organic Light‐Emitting Diodes with a Triazine Electron Transporter
Authors: Yamaguchi Kenta , Matsushima Toshinori , Sandanayaka Atula S. D. , Homma Yoko , Uchida Naoki , Adachi Chihaya 
Published: February 2020

AbstractIn organic light‐emitting diodes (OLEDs) based on materials that show thermally activated delayed fluorescence (TADF), the internal quantum efficiency of 100 % can be obtained without using phosphorescence‐based organometallics that contain rare metals. Therefore, with TADF‐based emitters, it is possible to fabricate high‐performing OLEDs at a lower cost. However, compared with fluorescence‐ and phosphorescence‐based OLEDs, an understanding of degradation mechanisms in TADF‐based OLEDs is still insufficient for future commercialization. In particular, it is widely recognized that the development of electron transport materials is crucial for improving OLED characteristics, especially driving voltages and operational durability. In this study, it was demonstrated that the operational durability of TADF‐based OLEDs was greatly improved by introducing a triazine‐based material of 2,4,6‐tris(1,1′‐biphenyl‐4‐yl)‐[1,3,5]triazine (pT2T) as a hole‐blocking layer (HBL) compared with a conventional HBL material of 2,4,6‐tris(biphenyl‐3‐yl)‐[1,3,5]triazine (T2T). Several experiments were carried out to make the reasons of the improved durability clearer, and attributed the improved durability to the shift of a carrier recombination zone from the emitting layer/HBL interface and the suppressed formation of excited‐state quenchers in the pT2T HBL, because of the higher electron mobility of pT2T and the better stability of its radical anion state.
A Regulable Internal Cavity inside a Resorcinarene‐Based Hemicarcerand
Authors: Harada Kentaro , Sekiya Ryo , Haino Takeharu 
Published: February 2020

AbstractCovalent organic capsules, such as carcerands and hemicarcerands, are an interesting class of molecular hosts. These container molecules have confined spaces capable of hosting small molecules, although the fact that the size of the inner cavities cannot be changed substantially limits the scope of their applications. The title covalently linked container was produced by metal‐directed dimerization of a resorcinarene‐based cavitand having four 2,2′‐bipyridyl arms on the wide rim followed by olefin metathesis at the vertices of the resulting capsule with a second‐generation Grubbs catalyst. The covalently linked bipyridyl arms permit expansion of the inner cavity by demetalation. This structural change influences the molecular recognition properties; the metal‐coordinated capsule recognizes only 4,4′‐diacetoxybiphenyl, whereas the metal‐free counterpart can encapsulate not only 4,4′‐diacetoxybiphenyl, but also 2,5‐disubstituted‐1,4‐bis(4‐acetoxyphenylethynyl)benzene, which is 9.4 Å longer than the former guest. Molecular mechanics calculations predict that the capsule expands the internal cavity to encapsulate the long guest by unfolding the folded conformation of the alkyl chains, which demonstrates the flexible and regulable nature of the cavity. Guest competition experiments show that the preferred guest can be switched by metalation and demetalation. This external‐stimuli‐responsive guest exchange can be utilized for the development of functional supramolecular systems controlling the uptake, transport, and release of chemicals.
Research into the oxidation of abietic acid–derived enone with atmospheric oxygen
Authors: Masnyk Marek , Kuśmirek Damian , Trzybiński Damian , Frelek Jadwiga 
Published: February 2020

AbstractThis work presents results of methyl 7‐oxoabiet‐13(14)‐en‐18‐oate (3) self‐oxidation with air‐oxygen in the presence of various bases such as triethylamine or sodium t‐butoxide. While under aerobic conditions, the use of sodium t‐butoxide as a base results in the formation of four isomeric alcohols, an addition of triethylamine into reaction medium directs the enone 3 oxidation to hydroperoxides. To clarify this base dependence and to obtain more in‐depth information about this reaction additional studies with cyclohexenone as a reference enone have been undertaken. Their results demonstrated the predisposition of abietane hydroperoxides to oxidize α,β‐unsaturated ketones to epoxides in the presence of t‐butoxide while reducing the hydroperoxide group to hydroxyl. This ability of hydroperoxides to epoxidize conjugated double bonds and confirmed by the present study intermolecular course allowed proposing a plausible mechanism for this reaction.
A multiscale absorption and transit model for oral drug delivery: Formulation and applications during fasting conditions
Authors: Kannan Ravishekar , Przekwas Andrzej 
Published: February 2020

AbstractMost Food and Drug Administration (FDA)‐approved drugs are administered orally, despite the complex process of oral drug absorption that is difficult to analyze experimentally. Oral bioavailability is dependent on the drug compound as well as the physiological and anatomical states of the user. Thus, computational models have emerged to mechanistically capture and predict the oral absorption process. The current models are generally 0D compartmental models and are limited by (a) simplified physiological characteristics of the gastrointestinal tract (GIT), (b) semiempirical/analytical dissolution profiles of the tested drugs, (c) incorrect absorption for some drug BCS classes (class IIa, for example), (d) GITs size variability among population, (e) incorrectly predicting the absorption of drugs that are GIT target specific, and (f) erroneous mixing in the domain. In this study, we have developed a multiscale absorption and transit (MAT) toolkit to simulate the dissolution, transport, absorption, distribution, metabolism, and elimination of orally administered drugs in the human GIT at multiple levels. MAT was constructed by integrating the spatially accurate first‐principles driven high‐fidelity drug transport, dissolution, and absorption model in the human stomach and GIT using our recently published quasi‐3D (Q3D) framework. The process integrated the multilayer intestine physiologically based pharmacokinetics models with the whole‐body compartmental models to predict the systemic pharmacokinetics of oral drugs. The computational results showed that this multiscale tool was able to match the experimental concentration results (individual and population) better than the traditional compartmental models. Ultimately, MAT will be developed into a commercial product to meet urgent demands from pharmaceutical and biomedical industries.
Gold Nanoparticles Stabilized by Molecular Fullerenols
Authors: Kokubo Ken , Espejo Cabello Mark Kristan , Sato Nozomi , Uetake Yuta , Sakurai Hidehiro 
Published: February 2020

AbstractPolyhydroxylated fullerene derivatives (fullerenols: C60(OH)12 and C60(OH)36) exhibit excellent stabilizing matrices for gold nanoparticles. Au:C60(OH)12 and Au:C60(OH)36 form hydrophilic colloids and are well dispersed in H2O, even though C60(OH)12 itself is barely dissolved in H2O. It was estimated that C60(OH)12 forms a two‐ to three‐layered structure with 3D O−H⋅⋅⋅O hydrogen‐bonding networks, surrounding approximately 3 nm‐sized Au NPs. The thus‐prepared Au:C60(OH)n colloids exhibited a high catalytic activity toward the reduction of 4‐nitrophenol to 4‐aminophenol. The short induction period as well as kinetic and thermodynamic parameters indicated the dynamic mobility of the fullerenol matrix and the hydrophobic nature of the interface between the Au surface and the matrix.
A sharp‐selective micro strip triplexer with hairpin resonators for long‐term evolution (LTE)
Authors: Mohammadi Pejman , Ebadzadeh Roghaye , Mohammadifar Maryam 
Published: February 2020

SummaryA compact size planar micro strip triplexer for long‐term evolution (LTE) is presented. The triplexer consists of three hairpin band pass filters and a T‐shaped micro strip line. T‐shaped microstrip line has been used as input signal splitting structure and hairpin filters bring sharp selectivity. Input impedance matching of the structure carried out with three metalized vias in the middle of the filters. The central pass band frequencies (0.9, 1.17, and 1.5 GHz) are selected according to LTE frequency bands. The pass band of the filters include 0.88 to 0.91, 1.16 to 1.21, and 1.47 to 1.53 GHz. Isolation among the output channels are better than 40 dB. The measurement results verify the design process satisfactorily. The proposed triplexer can be used in BTS antenna for enabling more than one transmitter on a single antenna.
Cocreating research priorities for anorexia nervosa: The Canadian Eating Disorder Priority Setting Partnership
Authors: Obeid Nicole , McVey Gail , Seale Emily , Preskow Wendy , Norris Mark L. 
Published: February 2020

AbstractObjectiveThe Canadian Eating Disorder Priority Setting Partnership was established to identify and prioritize the top 10 research priorities for females, 15 years or older, with anorexia nervosa, by incorporating equal input from those with lived experience, families, and healthcare professionals.MethodThis project, which closely followed the James Lind Alliance guidelines, solicited research priorities from the Canadian eating disorder community by means of a five‐step process including use of a survey, response collation, literature checking, interim ranking survey, and in‐person prioritization workshop.ResultsThe initial survey elicited 897 priorities from 147 individuals, with almost equal representation from all three stakeholder groups. From this, 603 responses aligned with the project objectives and were collapsed into 71 broader indicative questions. Based on available systematic reviews, 18 indicative questions were removed as they were considered answered by existing literature while 8 indicative questions were added from the recommendations of the reviews. In total, 61 indicative questions were ranked in an interim ranking survey, where 21 questions were prioritized as important by at least 20% of respondents. As a final step, 28 individuals from across Canada attended the prioritization workshop to coestablish the top 10 research priorities.DiscussionTop priorities were related to treatment gaps and the need for more surveillance data. This systematic methodology allowed for a transparent and collaborative approach to identifying current priorities from both the service user and provider perspective. Wide dissemination is anticipated to promote work that is of high relevance to patients, families, and clinicians.