bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pencil Code improves learners' computational thinking and computer learning attitude
Authors: Deng Wenbo , Pi Zhongling , Lei Weina , Zhou Qingguo , Zhang Wenlan 
Published: October 2019

AbstractIn the current implementation of K‐12 education, computational thinking is considered an important part of developing students' key abilities. Many studies have shown that computational thinking can be improved by programming, for example, using Scratch, App Inventor, and Python. However, different programming tools have different forms of programming that affect the development of learners' computational thinking. This study aimed to test the effects of different programming tools with the same teaching content on learners' computational thinking and computer learning attitude in real classroom teaching. Ninety‐nine participants took part in an eight‐week teaching intervention in the Visual Basic (text‐based) and Pencil Code (block‐based) programming environments. T tests showed that students learning in a mixed text‐based and block‐based Pencil Code programming environment not only had significantly improved computational thinking but also became more self‐confident and enjoyed learning programming. Furthermore, our interviews after the eight‐week teaching intervention found that students showed more communication and interaction behaviors learning with Pencil Code.
Models and Their Limitations in the Voltammmetric Parameterization of the Six‐Electron Surface‐Confined Reduction of [PMo12O40]3− at Glassy Carbon and Boron‐Doped Diamond Electrodes
Authors: Robinson Martin , Ounnunkad Kontad , Zhang Jie , Gavaghan David , Bond Alan M. 
Published: October 2019

AbstractIn acidic media, three well‐defined surface confined overall two electron transfer reactions derived from closely spaced one‐electron steps are observed in the DC and AC voltammetry of
. In this study, parameterization of these processes by sinusoidal AC voltammetry at glassy carbon (GC) and boron doped diamond (BDD) electrodes has been undertaken in 1 M HClO4. The experiment‐simulation comparison of even a simplified reaction scheme required estimation of 21 parameters, which is an exceptionally large number in voltammetry. The six reversible potentials were robustly recovered from data obtained at low (9.02 Hz) and higher (60.05 Hz) frequencies at both GC and BDD electrodes. Examination of the harmonic content by the Fourier transformed version of AC voltammetry enabled imperfections in the model associated with faradaic and non‐faradaic aspects of the voltammetry to be readily detected. After consideration of these imperfections, all processes were considered to be reversible within experimental uncertainty. Subtle differences in reversible potentials observed at both electrodes account for electrode dependence in shapes of the overall two electron steps. Fits of experimental data were superior using BDD at both frequencies and for the higher frequency GC case. Non‐compliance with an assumed potential independent model of the double layer capacitance was considered to be a significant contributor to discrepancies found with the GC electrode.
Understanding the Role of Solvents and Spin–Orbit Coupling in an Oxygen‐Assisted SN2‐Type Oxidative Transmetalation Reaction
Authors: Ghosh Boyli , Banerjee Ambar , Paul Ankan 
Published: October 2019

AbstractThe aerial oxidation of PdII to PdIV has emerged as an integral component of sustainable catalytic C−H functionalization processes. However, a proper understanding of the factors that control the viability of this oxidative process remains elusive. An investigation of the intricate mechanism of the transmetalation reaction of the aerial oxidative transformation of [(Me3tacn)PdIIMe2] (Me3tacn=N,N′,N′′‐trimethyl‐1,4,7‐triazacyclononane) to [(Me3tacn)PdIVMe3]+ has been conducted by using DFT, along with multireference methods, such as second‐order n‐electron valence‐state perturbation theory (NEVPT2) with complete active space self‐consistent field theory (CASSCF). The present endeavor predicts that the thermodynamics and kinetics of the oxygen activation step are primarily dictated by the polarity of the solvents, which determine the amount of charge transfer to the oxygen molecule from the PdII center. Additionally, it is observed that the presence of a protic solvent has a significant effect on the spin–orbit coupling term at the minimum energy crossing point of the triplet and singlet surfaces. Moreover, it is shown that the intermetal ligand‐transfer phenomenon is an important instance of an oxygen‐assisted SN2 reaction.
Reactivity of ZrO(MFP) and ZrO(RP) Nanoparticles with LnCl3for Solvatochromic Luminescence Modification and pH‐Dependent Optical Sensing
Authors: Wehner Tobias , Heck Joachim , Feldmann Claus , Müller‐Buschbaum Klaus 
Published: October 2019

AbstractThe luminescence of the inorganic–organic hybrid nanoparticles ZrO(MFP) (MFP=methylfluorescein phosphate) and ZrO(RP) (RP=resorufin phosphate) was modified by addition of different rare earth halides LnCl3. The resulting composite materials form dispersible nanoparticles that exhibit modified nanoparticle fluorescence depending on the rare earth ion. The resulting chromaticity of the luminescence is further variable by the employment of different solvents for ZrO(MFP)‐based composite systems. The strong solvatochromic effect of the MFP chromophore leads to different luminescence chromaticities of the composite materials between green, yellow, and blue in THF, toluene, and dichloromethane, respectively. The luminescence of ZrO(RP)‐based composite particles can be modified between the red and blue spectral regions in dependence on the applied reaction temperature. Beside a luminescence shift that is derived from nanoparticle modification by LnCl3, a strong turn‐on effect of ZrO(RP) particles results after contact with different Brønsted acids and bases in combination with a respective chromaticity shift. Both effects enable the potential employment of such particles as highly sensitive optical pH sensors.
Efficient Semi‐Synthesis of Atypical Ubiquitin Chains and Ubiquitin‐Based Probes Forged by Thioether Isopeptide Bonds
Authors: Chu Guo‐Chao , Hua Xiao , Zuo Chong , Chen Chen‐Chen , Meng Xian‐Bin , Zhang Zhongping , Fu Yao , Shi Jing , Li Yi‐Ming 
Published: October 2019

AbstractThe development of powerful and general methods to acquire ubiquitin (Ub) chains has prompted the deciphering of Ub‐mediated processes. Herein, the cysteine‐aminoethylation assisted chemical ubiquitination (CAACU) strategy is extended and improved to enable the efficient semi‐synthesis of atypical Ub chain analogues and Ub‐based probes. Combining the Cys aminoethylation and the auxiliary‐mediated protein ligation, several linkage‐ and length‐defined atypical Ub chains including di‐Ubs, K27C‐linked tri‐Ub, K11/K48C‐branched tri‐Ub, and even the SUMOlated Ub are successfully prepared from recombinantly expressed starting materials at about a 9–20 mg L−1 expression level. In addition, the utility of this strategy is demonstrated with the synthesis of a novel non‐hydrolyzable di‐Ub PA probe, which may provide a new useful tool for the mechanistic studies of deubiquitinase (DUB) recognition.
Frustrated Lewis Pair Chemistry Enables N2 Borylation by Formal 1,3‐Addition of a B−H Bond in the Coordination Sphere of Tungsten
Authors: Coffinet Anaïs , Specklin David , Vendier Laure , Etienne Michel , Simonneau Antoine 
Published: October 2019

AbstractThe first example of a formal 1,3‐B−H bond addition across the M−N≡N unit of an end‐on dinitrogen complex has been achieved. The use of Piers’ borane HB(C6F5)2 was essential to observe this reactivity and it plays a triple role in this transformation: 1) electrophilic N2‐borylation agent, 2) Lewis acid in a frustrated Lewis pair‐type B−H bond activation, and 3) hydride shuttle to the metal center. This chemistry is supported by NMR spectroscopy and solid‐state characterization of products and intermediates. The combination of chelate effect and strong σ donation in the diphosphine ligand 1,2‐bis(diethylphosphino)ethane was mandatory to avoid phosphine dissociation that otherwise led to complexes where borylation of N2 occurred without hydride transfer.
Indoles from Alkynes and Aryl Azides: Scope and Theoretical Assessment of Ruthenium Porphyrin‐Catalyzed Reactions
Authors: Intrieri Daniela , Carminati Daniela Maria , Zardi Paolo , Damiano Caterina , Manca Gabriele , Gallo Emma , Mealli Carlo 
Published: October 2019

AbstractA symbiotic experimental/computational study analyzed the Ru(TPP)(NAr)2‐catalyzed one‐pot formation of indoles from alkynes and aryl azides. Thirty different C3‐substituted indoles were synthesized and the best performance, in term of yields and regioselectivities, was observed when reacting ArC≡CH alkynes with 3,5‐(EWG)2C6H3N3 azides, whereas the reaction was less efficient when using electron‐rich aryl azides. A DFT analysis describes the reaction mechanism in terms of the energy costs and orbital/electronic evolutions; the limited reactivity of electron‐rich azides was also justified. In summary, PhC≡CH alkyne interacts with one NAr imido ligand of Ru(TPP)(NAr)2 to give a residually dangling C(Ph) group, which, by coupling with a C(H) unit of the N‐aryl substituent, forms a 5+6 bicyclic molecule. In the process, two subsequent spin changes allow inverting the conformation of the sp2 C(Ph) atom and its consequent electrophilic‐like attack to the aromatic ring. The bicycle isomerizes to indole via a two‐step outer sphere H‐migration. Eventually, a ′Ru(TPP)(NAr)′ mono‐imido active catalyst is reformed after each azide/alkyne reaction.
Practical Synthesis of Phosphinic Amides/Phosphoramidates through Catalytic Oxidative Coupling of Amines and P(O)−H Compounds
Authors: Tan Chen , Liu Xinyuan , Jia Huanxin , Zhao Xiaowen , Chen Jian , Wang Zhiyong , Tan Jiajing 
Published: October 2019

AbstractHerein, we report a highly efficient ZnI2‐triggered oxidative cross‐coupling reaction of P(O)−H compounds and amines. This operationally simple protocol provides unprecedented generic access to phosphinic amides/phosphoramidate derivatives in good yields and short reaction time. Besides, the reaction proceeds under mild conditions, which avoids the use of hazardous reagents, and is applicable to scale‐up syntheses as well as late‐stage functionalization of drug molecules. The stereospecific coupling is also achieved from readily available optically enriched P(O)−H compounds.
Dimerisation of Dipiperidinoacetylene: Convenient Access to Tetraamino‐1,3‐Cyclobutadiene and Tetraamino‐1,2‐Cyclobutadiene Metal Complexes
Authors: Hackl Ludwig , Petrov Alex R. , Bannenberg Thomas , Freytag Matthias , Jones Peter G. , Tamm Matthias 
Published: October 2019

AbstractThe reaction of 1,2‐dipiperidinoacetylene (1) with 0.5 equivalents of SnCl2 or GeCl2⋅dioxane afforded the 1,2,3,4‐tetrapiperidino‐1,3‐cyclobutadiene tin and germanium dichloride complexes 2 a and 2 b, respectively. A competing redox reaction was observed with excess amounts of SnCl2, which produced a tetrapiperidinocyclobutadiene dication with two trichlorostannate(II) counterions. Heating neat 1 to 110 °C for 16 h cleanly produced the dimer 1,3,4,4‐tetrapiperidino‐3‐buten‐1‐yne (3); its reaction with stoichiometric amounts of SnCl2 or GeCl2⋅dioxane furnished the 1,3,4,4‐tetrapiperidino‐1,2‐cyclobutadiene tin and germanium dichloride complexes 4 a and 4 b, respectively. Transition‐metal complexes containing this novel four‐membered cyclic bent allene (CBA) ligand were prepared by reaction of 3 with [(tht)AuCl], [RhCl(CO)2]2, and [(Me3N)W(CO)5] to form [(CBA)AuCl] (5), [(CBA)RhCl(CO)2] (6), and [(CBA)W(CO)5] (7). The molecular structures of all compounds 2–7 were determined by X‐ray diffraction analyses, and density functional theory (DFT) calculations were carried out to rationalise the formation of 3 and 4 a.
An under‐sampled software defect prediction method based on hybrid multi‐objective cuckoo search
Authors: Cai Xingjuan , Niu Yun , Geng Shaojin , Zhang Jiangjiang , Cui Zhihua , Li Jianwei , Chen Jinjun 
Published: October 2019

SummaryBoth the problem of class imbalance in datasets and parameter selection of Support Vector Machine (SVM) are crucial to predict software defects. However, there is no one working to solve these problems synchronously at present. To tackle this problem, a hybrid multi‐objective cuckoo search under‐sampled software defect prediction model based on SVM (HMOCS‐US‐SVM) is proposed to solve synchronously above two problems. Firstly, a hybrid multi‐objective cuckoo search with dynamical local search (HMOCS) is utilized to select synchronously the non‐defective sampling and optimize the parameters of SVM. Then, three under‐sampled methods for decision region range are proposed to select the non‐defective modules. In the simulation, the three indicators, including the false positive rate (pf), the probability of detection (pd), and G‐mean, are employed to measure the performance of the proposed algorithm. In addition, eight datasets from Promise database are selected to verify the proposed software defect predication model. Comparing with the result of eight prediction models, the proposed method comes into effect on solving software defect prediction problem.
A comparison of visual identification of dental radiographic and nonradiographic images using eye tracking technology
Authors: Botelho Michael G. , Ekambaram Manikandan , Bhuyan Sangeeta Y. , Yeung Andy Wai Kan , Tanaka Ray , Bornstein Michael M. , Li Kar Yan 
Published: October 2019

AbstractObjectivesEye tracking has been used in medical radiology to understand observers' gaze patterns during radiological diagnosis. This study examines the visual identification ability of junior hospital dental officers (JHDOs) and dental surgery assistants (DSAs) in radiographic and nonradiographic images using eye tracking technology and examines if there is a correlation.Material and methodsNine JHDOs and nine DSAs examined six radiographic images and 16 nonradiographic images using eye tracking. The areas of interest (AOIs) of the radiographic images were rated as easy, medium, and hard, and the nonradiographic images were categorized as pattern recognition, face recognition, and image comparison. The participants were required to identify and locate the AOIs. Data analysis of the two domains, entire slide and AOI, was conducted by evaluating the eye tracking metrics (ETM) and the performance outcomes. ETM consisted of six parameters, and performance outcomes consisted of four parameters.ResultsNo significant differences were observed for ETMs for JHDOs and DSAs for both radiographic and nonradiographic images. The JHDOs showed significantly higher percentage in identifying AOIs than DSAs for all the radiographic images (72.7% vs. 36.4%, p = .004) and for the easy categorization of radiographic AOIs (85.7% vs. 42.9%, p = .012). JHDOs with higher correct identification percentage in face recognition had a shorter dwell time in AOIs.ConclusionsAlthough no significant relation was observed between radiographic and nonradiographic images, there were some evidence that visual recognition skills may impact certain attributes of the visual search pattern in radiographic images.
Galectin‐3 modulates postnatal subventricular zone gliogenesis
Authors: Al‐Dalahmah Osama , Campos Soares Luana , Nicholson James , Draijer Swip , Mundim Mayara , Lu Victor M. , Sun Bin , Tyler Teadora , Adorján István , O'Neill Eric , Szele Francis G. 
Published: October 2019

AbstractPostnatal subventricular zone (SVZ) neural stem cells generate forebrain glia, namely astrocytes and oligodendrocytes. The cues necessary for this process are unclear, despite this phase of brain development being pivotal in forebrain gliogenesis. Galectin‐3 (Gal‐3) is increased in multiple brain pathologies and thereby regulates astrocyte proliferation and inflammation in injury. To study the function of Gal‐3 in inflammation and gliogenesis, we carried out functional studies in mouse. We overexpressed Gal‐3 with electroporation and using immunohistochemistry surprisingly found no inflammation in the healthy postnatal SVZ. This allowed investigation of inflammation‐independent effects of Gal‐3 on gliogenesis. Loss of Gal‐3 function via knockdown or conditional knockout reduced gliogenesis, whereas Gal‐3 overexpression increased it. Gal‐3 overexpression also increased the percentage of striatal astrocytes generated by the SVZ but decreased the percentage of oligodendrocytes. These novel findings were further elaborated with multiple analyses demonstrating that Gal‐3 binds to the bone morphogenetic protein receptor one alpha (BMPR1α) and increases bone morphogenetic protein (BMP) signaling. Conditional knockout of BMPR1α abolished the effect of Gal‐3 overexpression on gliogenesis. Gain‐of‐function of Gal‐3 is relevant in pathological conditions involving the human forebrain, which is particularly vulnerable to hypoxia/ischemia during perinatal gliogenesis. Hypoxic/ischemic injury induces astrogliosis, inflammation and cell death. We show that Gal‐3 immunoreactivity was increased in the perinatal human SVZ and striatum after hypoxia/ischemia. Our findings thus show a novel inflammation‐independent function for Gal‐3; it is necessary for gliogenesis and when increased in expression can induce astrogenesis via BMP signaling.
Unprecedented Nucleophilic Attack of Piperidine on the Electron Acceptor during the Synthesis of Push‐Pull Dyes by a Knoevenagel Reaction
Authors: Pigot Corentin , Noirbent Guillaume , Peralta Sébastien , Duval Sylvain , Nechab Malek , Gigmes Didier , Dumur Frédéric 
Published: October 2019

AbstractAn unprecedented nucleophilic addition of piperidine on an electron acceptor, namely, 2‐(3‐oxo‐2,3‐dihydro‐1H‐cyclopenta[b]naphthalen‐1‐ylidene)malononitrile is reported. This unexpected behavior was observed during the synthesis of push‐pull dyes using the classical Knoevenagel reaction. To overcome this drawback, use of diisopropylethylamine (DIPEA) enabled to produce the expected dyes PP1 and PP2. The optical and electrochemical properties of the different dyes were examined. Theoretical calculations were also carried out to support the experimental results. To evidence the higher electron‐withdrawing ability of this electron acceptor, a comparison was established with two dyes (PP3 and PP4) comprising its shorter analogue.
Soret effects on the mixed convection flow using Robin boundary conditions
Authors: Umavathi Jawali C. , Sheremet Mikhail A. , Patil Sapnali Limbraj 
Published: October 2019

AbstractAn investigation has been undertaken as Soret and Schmidt outcomes on the mixed convection flow using Robin boundary conditions. The results use a vertical channel being kept at constant cold temperature and concentration at the left wall and hot temperature and concentration at the right wall. The exchange of heat is done by help of plates with a fluid. We consider the external fluid with equal and different temperatures. This physical problem is solved by using nondimensional parameters with the corresponding boundary conditions. To find analytical solution, the regular perturbation series method is used, and for finding the numerical solution, the well‐known Runge–Kutta method with shooting technique is employed. Comparison of the current study is favorable with the previous published results. The obtained results depend on the governing parameters such as thermal Grashof number, solutal Grashof number, Biot numbers, symmetric and asymmetric wall temperatures, Schmidt number, Soret number, and Brinkman number. An influence of these parameters on the fields of velocity, temperature, and concentration is reported. Further, the numerical results for the Nusselt number, mean value of the velocity, dimensionless bulk temperature, skin friction, and molecular diffusion coefficient are tabulated for different parametric conditions and explained. For small value of Brinkman number, the obtained values agree with other published results for all considered cases.
High Plasma Erythropoietin Predicts Incident Fractures in Elderly Men with Normal Renal Function: The MrOS Sweden Cohort
Authors: Kristjansdottir Hallgerdur Lind , Lewerin Catharina , Lerner Ulf H. , Herlitz Hans , Johansson Peter , Johansson Helena , Karlsson Magnus , Lorentzon Mattias , Ohlsson Claes , Ljunggren Östen , Mellström Dan 
Published: October 2019

ABSTRACT
Preclinical studies on the role of erythropoietin (EPO) in bone metabolism are contradictory. Regeneration models indicate an anabolic effect on bone healing, whereas models on physiologic bone remodeling indicate a catabolic effect on bone mass. No human studies on EPO and fracture risk are available. It is known that fibroblast growth factor 23 (FGF23) affects bone mineralization and that serum concentration of FGF23 is higher in men with decreased estimated glomerular filtration rate (eGFR). Recently, a direct association between EPO and FGF23 has been shown. We have explored the potential association between EPO and bone mineral density (BMD), fracture risk, and FGF23 in humans. Plasma levels of EPO were analyzed in 999 men (aged 69 to 81 years), participating in the Gothenburg part of the population-based Osteoporotic Fractures in Men (MrOS) study, MrOS Sweden. The mean ± SD EPO was 11.5 ± 9.0 IU/L. Results were stratified by eGFR 60 mL/min. For men with eGFR ≥60 mL/min (n = 728), EPO was associated with age (r = 0.13, p &lt; 0.001), total hip BMD (r = 0.14, p &lt; 0.001), intact (i)FGF23 (r = 0.11, p = 0.004), and osteocalcin (r = −0.09, p = 0.022). The association between total hip BMD and EPO was independent of age, body mass index (BMI), iFGF23, and hemoglobin (beta = 0.019, p &lt; 0.001). During the 10-year follow-up, 164 men had an X-ray–verified fracture, including 117 major osteoporotic fractures (MOF), 39 hip fractures, and 64 vertebral fractures. High EPO was associated with higher risk for incident fractures (hazard ratio [HR] = 1.43 per tertile EPO, 95% confidence interval [CI] 1.35–1.63), MOF (HR = 1.40 per tertile EPO, 95% CI 1.08–1.82), and vertebral fractures (HR = 1.42 per tertile EPO, 95% CI 1.00–2.01) in a fully adjusted Cox regression model. In men with eGFR&lt;60 mL/min, no association was found between EPO and BMD or fracture risk. We here demonstrate that high levels of EPO are associated with increased fracture risk and increased BMD in elderly men with normal renal function. © 2019 American Society for Bone and Mineral Research.
Selective cytochrome P450 1A1 but not 1B1 promoterCpG island DNA methylation by 6‐formylindolo[3,2‐b]carbazole (FICZ)
Authors: Ghaedi Afsaneh , Keshavarzi Majid , Ghafarian Bahraman Ali , Mohammadi‐Bardbori Afshin 
Published: October 2019

AbstractEpigenetic alterations are essential for normal mammalian development and regulation of gene expression. In this study, we aimed to determine if an enigmatic endogenous ligand of the aryl hydrocarbon receptor (AHR), 6‐formylindolo[3,2‐b]carbazole (FICZ), and methionine (Meth) have an epigenetic impact on AHR‐regulated cytochrome P450 1A1 and B1 (CYP1A1 and CYP1B1) gene expression. Human hepatoma (HepG2‐XRE‐Luc and huh7) cells were exposed to FICZ in a medium with and without Meth supplementation. Selective and transient silencing of CYP1A1 but not CYP1B1 were seen by FICZ. Here we found that FICZ transiently represses CYP1A1 by targeting DNA (cytosine‐5)‐methyltransferase 3A (DNMT3A) and concomitant DNA methylation of the CYP1A1 promoter gene. Treatments with 5‐aza‐dC augmented CYP1A1 transcription activity. Our results reveal a new mechanism for transient activation of AHR by FICZ that can negatively and positively influence gene expression, and highlight the regulatory role of Meth on the CYP1A1 gene expression.