bluuebunny/crossref_metadata_2025_split huggingface dataset:
Students’ representational competence with drawing technology across two domains of science
Authors: Chang Hsin‐Yi 
Published: June 2018

AbstractResearch has indicated the importance of representational competence for learning science. Issues related to the nature of students’ representational competence, such as how they demonstrate representational competence across different domains of science, require investigation. In the present study, four aspects of representational competence across two domains of science were investigated: use of dynamic representations, use of multiple representations, use of adequate science concepts, and use of visualization strategies. Two instruments, the representational competence of states of matter and the representational competence of carbon cycling assessments were delivered via a computer‐based drawing tool and were used to measure 40 senior high school students’ representational competence for the topic of states of matter and carbon cycling. The results indicated that the representational competence demonstrated in one topic was not significantly correlated to that demonstrated in the other. The results of path analyses using multiple regressions indicated a trend that the extent to which multiple representations were employed was significantly and closely related to the extent to which appropriate science concepts were applied to make the drawings. Implications of the findings are discussed.
Synthesis and Characterization of N5‐(2‐Fluoro‐2,2‐dinitroethyl)‐N1‐methyl‐1H‐tetrazole‐5‐amine and its Nitramide Based on Functionalized Amino Group in 5‐Amino‐1H‐tetrazole
Authors: Li Jie , Zhang Guojie , Zhang Zhenqi , Ma Qing , Fan Guijuan , Tang Shuihua 
Published: June 2018

AbstractN5‐(2‐fluoro‐2,2‐dinitroethyl)‐N1‐methyl‐1H‐tetrazole‐5‐amine and its nitramide were designed and synthesized by a strategy based on functionalized amino group in 5‐amino‐1H‐tetrazole. Their structures were fully determined by 1H, 13C NMR, infrared spectrum as well as elementary analysis. Single‐crystal X‐ray diffraction was employed for characterizing their crystal structures. Comparing with its nitramide N5‐(2‐fluoro‐2,2‐dinitroethyl)‐N1‐methyl‐1H‐tetrazol‐5‐yl)‐nitramide (Tm: 76 oC, Td: 135 oC, Tp: 163 oC), N5‐(2‐fluoro‐2,2‐dinitroethyl)‐N1‐methyl‐1H‐tetrazole‐5‐amine exhibits better thermal stability (Tm: 167 oC, Td: 191 oC, Tp: 205 oC), which is superior to those of N3,N4‐bis(2‐fluoro‐2,2’‐dinitroethyl)‐1,2,5‐oxadiazole‐3,4‐diamine (LLM‐208) (Tm: 149 oC, Tp: 188 oC). They both present insensitivity towards impact but slightly sensitive to friction. It is worth noting that N5‐(2‐fluoro‐2,2‐dinitroethyl)‐N1‐methyl‐1H‐tetrazol‐5‐yl)‐nitramide shows its detonation performance approaching those of RDX. The above‐mentioned energetic performance show that they are insensitive and worth further potential applications as oxidizers, melt‐cast explosives, energetic plasticizers, or high‐performance ligands for constructing energetic coordination polymers.
Belt‐Like Cobalt Phosphate Tetrahydrate as the Non‐Noble Metal Catalyst with Enhanced Catalytic Reduction Activity
Authors: Su Hang , Xu Man , Zhou Shijian , Yang Fu , Wang Bangbang , Shao Bo , Kong Yan 
Published: June 2018

AbstractIn this work, the belt‐like cobalt phosphate tetrahydrate (Co−P‐HT) was successfully synthesized by the hydrothermal method without adopting template and complicated manipulation. To the best of our knowledge, the as‐prepared Co−P based materials were used as heterogeneous catalysts to catalytic reduction of organic molecules (e. g., 4‐nitrophenol) at room temperature for the first time. Especially, the Co−P‐HT exhibited enhanced catalytic reduction activity by about 3.59 times higher than that of the plate‐like cobalt phosphate octahydrate (Co−P‐RT). Moreover, Co−P‐HT also exhibited excellent catalytic activity than some noble metal‐containing materials. In addition, the Co−P‐HT could maintain its enhanced catalytic activity after the four successive catalytic test, further confirming the stability of this material. The characterization results demonstrated that the as‐prepared Co−P based materials presented distinguishable physicochemical properties, such as different chemical compositions, morphologies, coordination environments and the ability of electrons transfer and distribution. Besides, a formation mechanism of Co−P‐HT was purposed in which this material could be obtained from Co−P‐RT. The Co−P‐HT could be considered as the potential catalyst to substitute some cobalt‐based and noble metal‐containing materials in mild conditions.
Design, Synthesis, Opto–Electrochemical and Theoretical Investigation of Novel Indolo[2, 3‐b]naphtho[2, 3‐f]quinoxaline Derivatives for n–Type Materials in Organic Electronics
Authors: Kamble Rajesh M. , Sharma Bharat K. , Shaikh Azam M. , Chacko Sajeev 
Published: June 2018

AbstractA series of seven new donor–acceptor compounds based on indolo[2, 3‐b]naphtho[2, 3–f] quinoxaline were synthesized by using Buchwald–Hartwig amination reaction between 12–bromo–9–heptyl–5H–indolo[2, 3–b]naphtho[2, 3–f]quinoxaline‐5,15‐(9H)–dione (1) and diaryl/cyclic amine (2–5) and by Suzuki–Miyaura coupling reaction of 1 with aryl boronic acid (6–8). The synthesized molecules were studied to determine their absorption, emission, electrochemical, thermal properties. Theoretical properties were also studied by time dependent density functional theory (TD‐DFT). The HOMO and LUMO energy levels of 2–8 are in the range of −6.51 to −6.84 eV and –3.00 to –3.30 eV respectively. Low−lying LUMO energy levels of 2–8 are very similar to well−known n−type materials. On the basis of experimental and theoretical studies synthesized compounds could act as n−type materials in organic electronics.
Synthesis of Highly Functionalized Tricyclic Chromenopyrazole Frameworks via Intramolecular Azomethine Imine 1,3‐Dipolar Cycloaddition (IAIDC)
Authors: Bakthadoss Manickam , Agarwal Vishal 
Published: June 2018

AbstractA general protocol for the synthesis of angularly substituted tricyclic chromenopyrazoles via an intramolecular azomethine imine 1,3‐dipolar cycloaddition (IAIDC) reaction of O‐allylated salicylaldehydes (derived from bromo derivatives of Baylis‐Hillman adducts) and aryl hydrazines has been described for the first time. This reaction creates two rings (six and five‐membered) via the formation of one C–C bond and two C−N bonds. Moreover, the products are formed with two chiral centers with high diastereoselectivity and stereospecificity. Some of the synthesized compounds were examined for the fluorescent properties and found to exhibit strong fluorescence in the blue region.
Amidooxime‐Based Mononuclear Mn(II) Complexes: Synthesis, Characterization, and Studies on DNA Binding and Nuclease Activity
Authors: Dolai Malay , Saha Urmila , Kumar Gopinatha S. , Ali Mahammad 
Published: June 2018

AbstractA number of new amidooxime based manganese(II) complexes have been synthesized and characterized by single crystal X‐ray diffraction studies as well as by geometry optimization of complex 2 using DFT/B3LYP. All four complexes (1‐4) are mononuclear having octahedral geometry. DNA binding interaction and nuclease activity of these compounds were investigated for diverse biomedical applications. The results of photophysical studies indicated that the Mn(II) compounds bind with DNA by intercalation mode and the complex 1 containing pyrimidine moiety and chloro ligation showed highest binding affinity. The binding affinities of these compounds were of the order of 104‐105 M−1 and all of them were found to be capable of inducing DNA cleavage.
First‐Principles Study on the Adsorption of HF on Reduced Graphene Oxide
Authors: Zhao Meilian , Lai Qiao , Xiao Dan , Guo Yong 
Published: June 2018

AbstractHydrogen Fluoride (HF), a toxic and corrosive colorless gas, is hazardous to human health. It is important to explore sensor materials to detect HF and remove it. Reduced graphene oxide (rGO) is a new carbon‐based material with large adsorption ability and high conductivity. In this work, the adsorption of HF on rGO is investigated by M06‐2X functional. The adsorption of HF is stronger on rGO than graphene, which is attributed to the existance of active defect sites in rGO, e. g., epoxide, hydroxyl,carboxyl groups and the carbon atoms near these functional groups. O⋅⋅⋅H and F⋅⋅⋅H bonds form during the interaction between HF and rGO. The type and substituted site of oxygen‐containing group in rGO affect the adsorption ability. Carboxyl group is much more attractive than epoxide and hydroxyl group in rGO for HF. Spin density plays an important part in enhancing the adsorption. The adsorption is the strongest for HF on rGO with carboxyl group connected to vacancy in our work.
Ag(I)/(C2H5)4NCl Cooperation Catalysis for Fixing CO2 or Its Derivatives into β‐Oxopropylcarbamates
Authors: Zhao Qing‐Ning , Song Qing‐Wen , Liu Ping , Zhang Kan , Hao Jian 
Published: June 2018

AbstractIt remains a great challenge to convert CO2 into high value‐added products under ambient pressure. Herein, an efficient dual‐component catalytic system, i. e., Ag(I)/(C2H5)4NCl was developed for the synthesis of various β‐oxopropylcarbamates via one‐pot three‐component coupling of CO2, secondary amines and propargylic alcohols under atmospheric pressure. Besides, the strategy avoided the use of any additional ligand and basic species, and excellent selectivity was achieved with a yield of up to 98%. Additionally, 13Ccarbonyl‐labeled and control experiments were carefully performed to demonstrate the mechanism. Notably, this new method was also applied efficiently in quantitative chemical fixation of CO2, i. e., the two‐component reaction of propargylic alcohols and ammonium carbamates.
Detailed Investigation into the Preparation of Graphene Oxide by Dichromate Oxidation
Authors: Rosillo‐Lopez Martin , Salzmann Christoph G. 
Published: June 2018

AbstractGraphene oxide (GO) can be prepared using numerous protocols including the well‐known Hummers method that relies on potassium permanganate as the oxidizing agent. Given the widespread use of GO and its many applications, a better understanding of the mechanisms of chemical oxidation is highly desirable including research into alternative oxidizing agents. Limited work has so far been carried out into using potassium dichromate as an oxidizing agent and the chemical structure of GO prepared by dichromate oxidation remains unclear. Here we present a full structural characterization of GO prepared by dichromate oxidation and we investigate its thermal stability. Furthermore, the previously reported preparation protocol is optimized by reducing the reaction time from 5 days to 20 hours and showing that sodium nitrate is not needed in the reaction mixture. Contrary to previous reports, we show that the GO material produced by dichromate oxidation is highly oxidized if thermal annealing is avoided. Compared to traditional GO, larger amounts of carboxylic acid groups are found which constitutes a major advantage for chemical processing and applications in materials chemistry.
Recent Advances and Developments of in vitro Evaluation of Heterocyclic Moieties on Cancer Cell Lines
Authors: Tandon Runjhun , Singh Iqubal , Luxami Vijay , Tandon Nitin , Paul Kamaldeep 
Published: June 2018

AbstractBesides worthy development in cancer therapy, cancer is still one of the leading causes of death, worldwide. The future burden of cancer will probably be even larger because people are adopting poor lifestyles with poor diet, frequently smoking and less physical activity. The effective anticancer drugs having efficacy and selectivity with low toxicity is still a challenge for the scientific fraternity. The advances in the cancer study have its origin on the availability of different types of experimental model systems that review the various forms of this disease. Cell lines emerge as a feasible alternative for anticancer activities, being at the same time easy to manipulate and molecularly characterize. Heterocycles are key structural components of many of the anti‐cancer drugs available on the market today. Indeed, of the novel molecular anti‐cancer agents approved by the FDA between 2010 and 2017, almost two‐thirds contained heterocyclic rings within their structures. This review summarizes and provides updated literature on heterocyclic compounds using various cancer cell lines reported during the period of 2014–2017 together with the structure‐activity relationships.
Talking back: Development of the olivocochlear efferent system
Authors: Frank Michelle M. , Goodrich Lisa V. 
Published: June 2018

Developing sensory systems must coordinate the growth of neural circuitry spanning from receptors in the peripheral nervous system (PNS) to multilayered networks within the central nervous system (CNS). This breadth presents particular challenges, as nascent processes must navigate across the CNS–PNS boundary and coalesce into a tightly intermingled wiring pattern, thereby enabling reliable integration from the PNS to the CNS and back. In the auditory system, feedforward spiral ganglion neurons (SGNs) from the periphery collect sound information via tonotopically organized connections in the cochlea and transmit this information to the brainstem for processing via the VIII cranial nerve. In turn, feedback olivocochlear neurons (OCNs) housed in the auditory brainstem send projections into the periphery, also through the VIII nerve. OCNs are motor neuron‐like efferent cells that influence auditory processing within the cochlea and protect against noise damage in adult animals. These aligned feedforward and feedback systems develop in parallel, with SGN central axons reaching the developing auditory brainstem around the same time that the OCN axons extend out toward the developing inner ear. Recent findings have begun to unravel the genetic and molecular mechanisms that guide OCN development, from their origins in a generic pool of motor neuron precursors to their specialized roles as modulators of cochlear activity. One recurrent theme is the importance of efferent–afferent interactions, as afferent SGNs guide OCNs to their final locations within the sensory epithelium, and efferent OCNs shape the activity of the developing auditory system.This article is categorized under:Nervous System Development > Vertebrates: Regional Development
Aerodynamic analysis of a linear cascade wind turbine
Authors: Jafari S. A. H. , Kwok K. C .S. , Safaei F. , Kosasih B. 
Published: June 2018

AbstractThis paper develops an analytical model to investigate the aerodynamic of the power generation of a linear cascade wind turbine, referred to as PowerWindow. Based on blade element momentum theory, this analytical model elucidates some flow characteristics of PowerWindow such as axial induction factor and local instantaneous angle of attack along the blades. The model also provides an understanding of the effects of blade pitch angle, blade speed ratio, and solidity on the angle of attack, axial induction factor, and power generation of PowerWindow when operating in “elevated” position. In elevated position, PowerWindow is installed on a tower as opposed to directly mounted on a roof. The validity and accuracy of the analytical model are verified with computational fluid dynamic simulations. The results indicate that by doubling the solidity or increasing the blade pitch angle by 8°, the coefficient of performance of PowerWindow increases from 8% to 12% and 16%, respectively. The analytical model can serve as the tool to find the design parameters of PowerWindow and their influence on power generation for given life wind condition.
Analysis of near‐surface relative humidity in a wind turbine array boundary layer using an instrumented unmanned aerial system and large‐eddy simulation
Authors: Adkins Kevin A. , Sescu Adrian 
Published: June 2018

AbstractSimulation and modeling have shown that wind farms have an impact on the near‐surface atmospheric boundary layer as turbulent wakes generated by the turbines enhance vertical mixing. While a few observational data sets that focus on near‐surface temperature changes exist, these studies lack high spatial resolution and neglect the combined effect of these temperature changes with an altered humidity profile. With a large portion of wind farms hosted within an agricultural context, changes to relative humidity can potentially have secondary impacts, such as to the productivity of crops. The goal of this study is to gather high‐resolution in situ field measurements in the wake of a single wind turbine in order to differentially map downstream changes to relative humidity. These measurements, obtained by an instrumented unmanned aerial system, are complemented by numerical experiments conducted using large‐eddy simulation. Observations and numerical results are in good general agreement around a single wind turbine and show that downstream relative humidity is differentially altered in all directions, specifically decreased below the turbine hub height. Large‐eddy simulation is then used to determine the effect of a large 7 × 4 turbine array on the relative humidity distribution in compounding wakes. It is found that the region of relative humidity decrease below the turbine hub height and the region of increase above the hub height both intensify, differentially extend in the lateral directions, and move slightly upward with downstream distance.
The potential of performance targets (imihigo) as drivers of energy planning and extending access to off‐grid energy in rural Rwanda
Authors: Bisaga Iwona , Parikh Priti , Mulugetta Yacob , Hailu Yohannes 
Published: June 2018

Rwanda has one of the lowest electrification rates in Sub‐Saharan Africa and ambitious targets of boosting energy access, with an encouraged private sector involvement. However, barriers such as end‐user awareness and participation in policy and business model design prohibit the pace of rural electrification. A case of Rwanda is analyzed, pointing to the potential of the imihigo (performance contracts) framework. Given the adoption of household‐level performance contracts, which can include energy access, it is proposed they could drive local participation among off‐grid communities. Results of a survey with 218 users of Solar Home Systems in North‐Western Rwanda and from five focus groups show that village‐level energy targets impact on the prioritization of energy target setting among households. Including off‐grid energy options in the imihigo booklets distributed to households could influence awareness raising and allow private sector providers to act in a more targeted way, prioritizing areas with most prevalent energy targets. Additionally, community meetings (umuganda) tied to imihigo offer participatory spaces for information and feedback sharing. These will assist in the design of energy planning and business models, which best fit local needs and respond to the challenges faced by the energy poor.This article is categorized under:
Energy and Development > Climate and Environment
Energy Policy and Planning > Economics and Policy
Knowledge discovery and semantic learning in the framework of axiomatic fuzzy set theory
Authors: Liu Xiaodong , Jia Wenjuan , Wang Yuangang , Guo Hongyue , Ren Yan , Li Zedong 
Published: June 2018

Axiomatic fuzzy set (AFS) theory facilitates a way on how to transform data into fuzzy sets (membership functions) and implement their fuzzy logic operations, which provides a flexible and powerful tool for representing human knowledge and emulate human recognition process. In recent years, AFS theory has received increasing interest. In this survey, we report the current developments of theoretical research and practical advances in the AFS theory. We first review some notion and foundations of the theory with an illustrative example, then, we focus on the various extensions of AFS theory for knowledge discovery, including clustering, classification, rough sets, formal concept analysis, and other learning tasks. Due to its unique characteristics of semantic representation, AFS theory has been applied in multiple domains, such as business intelligence, computer vision, financial analysis, and clinical data analysis. This survey provides a comprehensive view of these advances in AFS theory and its potential perspectives.This article is categorized under:

Technologies > Computational Intelligence
Microscopic considerations for optimizing silk biomaterials
Authors: DeBari Megan K. , Abbott Rosalyn D. 
Published: June 2018

Silk is an especially appealing biomaterial due to its adaptable mechanical properties, allowing it to be used in a wide range of tissue engineering applications. However, processing conditions play a critical role in determining silk's mechanical properties, biodegradability, and biocompatibility. While bulk properties of silk have been widely explored, focusing on microscopic features is becoming increasingly important, as modifications at this scale largely affect the resulting regenerative properties of the biomaterial. Structural changes caused by the silk source, extraction, and processing should be carefully considered, as they will affect the biocompatibility and degradability of silk fibroin. Processing techniques and physical properties of silk that make it an ideal material for many biomedical applications will be explored.This article is categorized under:

Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement
Implantable Materials and Surgical Technologies > Nanomaterials and Implants
Stenting in Palliation of Unresectable Esophageal Cancer
Authors: Włodarczyk Janusz R , Kużdżał Jarosław 
Published: June 2018

AbstractBackgroundThe aim of this study was to analyze the safety and effectiveness of stenting using partially covered self‐expandable stents in palliation of dysphagia in patients with unresectable esophageal cancer.MethodsRetrospective analysis of hospital records of all patients who underwent esophageal stenting in the period 2008–2015 was performed. The study included patients with unresectable esophageal and esophagogastric cancer.ResultsThere were 442 patients included. Mean age was 56 years (range 28–89), and 379 were males. In 40 (9.0%) patients, stenting was performed in the cervical, in 150 (39.3%)—in the middle thoracic, in 141 (31.9%)—in lower thoracic esophagus and in 111 (25.1%)—in the esophagogastric junction. Stenting resulted in significant alleviation of dysphagia grade (3.0 vs. 1.0, p = 0.00001). During the follow‐up, 55 (12.4%) patients experienced recurrent dysphagia due to tumor or granulation tissue overgrowth, and in 18 (4.1%) patients, migration of the stent occurred, for which an independent risk factor was adjuvant chemo‐ and/or radiation therapy (p = 0.001). Minor complications included chest pain (54.5%), delayed complete stent expansion (12.0%), feeling of a foreign body (25.3%), hiccup (1.6%), gastroesophageal reflux (45.6%) and post‐discharge pneumonia (2.5%). A feeling of a foreign body in the esophagus was significantly more common after stenting of the cervical esophagus (p = 0.0001), and hiccup was more common after stenting of the esophagogastric junction (p = 0.02). Major complications included bleeding (1.3%), respiratory insufficiency (0.7%), esophageal perforation (0.9%) and irregular heartburn (2.3%). Overall procedure‐related mortality was 0.4%. The median survival time was 117.8 days (range 2–732).ConclusionsStenting is an effective procedure in relieving dysphagia in patients with unresectable malignant esophageal stenosis and is associated with low rate of postoperative and long‐term complications.