bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Bayesian approach to diagnosing covariance matrix shifts
Authors: Wang Binhui , Xu Feng , Shu Lianjie 
Published: December 2019

AbstractIn addition to the quick detection of abnormal changes in a multivariate process, it is also critical to provide an accurate fault identification of responsible components following an out‐of‐control signal. In line with the work of Tan and Shi for diagnosing shifts in the mean vector, this paper develops a Bayesian approach for diagnosing shifts in the covariance matrix. The simulation comparisons favor the proposed approach. A real example is also presented to demonstrate the implementation of the proposed method.
A DFT study on mechanisms of CO2 coupling with propargylic alcohols using alkali carbonates
Authors: Li Weiyi , Leng Geng , Li Caiqin , Lyu Yajing 
Published: December 2019

AbstractThe mechanisms of CO2 coupling with the propargylic alcohol using alkali carbonates M2CO3 (M = Li, Na, K, Cs) have been investigated by means of density functional theory calculations. The calculations reveal that the target product tetronic acid (TA) is yielded through two stages: (a) the formation of the α‐alkylidene cyclic carbonate (αACC) intermediate via Cs2CO3‐mediated carboxylative cyclization of the propargylic alcohol with CO2, and (b) the conversion of the αACC intermediate with Cs2CO3 to produce the cesium salt of the TA. Since the overall kinetic barriers for the two stages are comparable and affordable, the excellent chemoselectivity to the TA should be primarily originated from the high thermodynamic stability of the cesium salt of the TA. Moreover, relative to the TA, the possibility to yield the by‐product acyclic carbonate can be excluded due to the both kinetics and thermodynamic inferiority. This result is different from the organic base‐mediated reaction. Alternatively, our calculations predict that CsHCO3 together generated with the cesium salt of the TA might also be an available mediating reagent for the incorporation of CO2 with the propargylic alcohol. Compared to other alkali carbonates M2CO3 (M = Li, Na, K), the stronger basicity of Cs2CO3 and the lower ionic potential of cesium ion can raise the effective concentration of the αACC intermediate, and thus the conversion of the αACC intermediate into the cesium salt of the TA can be achieved with high yield.
A Sulfonated Porous Polymer as Solid Acid Catalyst for Biofuel Synthesis and Chemical Fixation of CO2
Authors: Dey Tusar Kanto , Bhanja Piyali , Basu Priyanka , Ghosh Aniruddha , Islam Sk. Manirul 
Published: December 2019

AbstractDeforestation and uncontrolled emission of carbon dioxide (CO2) through abundant use of fossil fuels result global warming. This serious threat to the atmosphere has deeply motivated the researchers to develop new strategies for chemical fixation of CO2 and biofuel synthesis. Here we report the sulfonated porous polytriphenylamine (SPPTPA‐1, BET surface area of 664 m2 g−1, pore volume 0.386 cc g−1) as an efficient heterogeneous catalyst for the synthesis of cyclic carbonates via CO2 fixation into epoxides. SPPTPA‐1 catalyst contains pores with dimension of 1.8‐2.0 nm, which produced a H1 type hysteresis loop in N2 adsorption/desorption isotherm. The porous catalyst is thermally stable upto 196 °C. The synthesized SPPTPA‐1 catalyst contains large amount of surface acidic sites. Further, it catalyzes the esterification reaction of levulinic acid, long chain fatty acids and dicarboxylic acids due to presence of its acidic sites. This solid acid catalyst SPPTPA‐1 showed excellent recycling efficiency upto 5 times in all these demanding reactions.
Role of X‐ray Scattering Techniques in Understanding the Collagen Structure of Leather
Authors: Buchanan Jenna K. , Zhang Yi , Holmes Geoff , Covington Anthony D. , Prabakar Sujay 
Published: December 2019

AbstractThis review focuses on the SAXS and WAXS analysis of the collagen structure of leather, from pioneering works through to recent developments. X‐ray scattering can be used to investigate the structural features of fibrillar collagen in the leather matrix, including axial periodicity, fibril diameter, chemical fixation, hydration and fibrillar orientation. Key properties of leather, such as appearance, handle, strength, hydrothermal stability and resistance to putrefaction, are closely linked to these parameters, thereby underlining the importance of X‐ray scattering to the study of leather. Recent research on the molecular level changes in collagen structure at different stages of leather processing with a range of treatments is also summarized. We will highlight how studies using X‐ray scattering techniques have provided significant insights into tanning processes which could be used to improve leather properties and optimize/reduce the use of tanning agents such as chromium (III) in the industry. The review will also describe the details of collagen structure and tanning mechanisms that are yet to be determined by X‐ray scattering, as well as future advancements of this technique and what it can accomplish for the leather industry.
Catalytic Efficiency of Biosynthesized Silver Nanoparticles in Synthesis of Chromones and Reduction of Nitro Aromatics
Authors: Kandula Venu , Balakrishna C. , Behera Manoranjan , Nagababu Uppu , Kumar G. Kiran , Chatterjee Anindita 
Published: December 2019

AbstractSilver nanoparticles (AgNps) were biosynthesized and characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), UV‐visible absorption (UV‐vis) and photoluminescence spectroscopy. The average size of the nanoparticles was found to be around 20 nm from TEM and surface plasmon band appeared at 420 nm. The nanoparticles are highly crystalline and possess face‐centered cubic (fcc) structures. These nanoparticles were used for the synthesis of chromones by a simple, mild and efficient method using microwave irradiation. Good yield upto 82% has been achieved for the synthesis of chromones. Further, the AgNps were used in reduction of aromatic nitro compounds to corresponding anilines with high yield. All reactions were studied under benign reaction conditions without using any hazardous organic solvents, expensive ligand or activator.
Evolution of Electronegativity of Chlorinated Sulfur‐Containing and Organic Compounds from Neutral to Core‐Excited/Ionized States
Authors: Carniato Stéphane 
Published: December 2019

AbstractAbsolute electronegativity of chlorinated ‐[CnH2nSCl (n=1,2,4)] sulfur‐containing groups and organic systems in their isolated forms has been theoretically evaluated with the help of ionization potential/electronic affinities calculations. The variation of the electronegativity of these groups when bond formation with an atomic chlorine was estimated between 1–4 in the Pauling scale within the frozen orbitals approximation (Koopman's theorem) applied to the Cl2s core‐level. The fluctuation of the electronegativity when removing explicitly one Cl 2 s inner‐shell electron has been also investigated for the series. Taking into account relaxation and correlation effects we show that core ionization produces a large increase of the group electronegativity by two units (3‐6 in the Pauling scale). The change of the electronegativity after Cl1s
LUMO core excitation and subsequent KL radiative decay in resonant inelastic x‐ray scattering process has been also followed through the analysis of the weight of the Cl 2p(z)−1LUMO1 component aligned along the R−Cl chemical bond and contributing to the Cl 2p3/2 spin‐orbit state. Electronegativities are found in the same range (1‐3) as for the initial ground state due to screening of the core‐vacancy by the promoted single electron onto the lowest unoccupied molecular orbital (LUMO). Subtle fluctuations of the chemical group electronegativity and relaxation/correlation processes with the sulfur position in the chains are discussed.
Magnetic and Optical Properties of Ag‐CoFe Nanohybrids Prepared by a Sequenced Microfluidic Process
Authors: Ma Jugang , Wang Junmei , Zhang Guangqing , Peng Lifan , Song Xiangrong , Ding Jie , Ji Shaoxia , Song Yujun 
Published: December 2019

AbstractMetal‐based magnetic nanoparticles (NPs) with hybrid structures are currently attracting extensive attention due to the synergistic effects among constructing components. Their unique physicochemical properties endow them with widespread applications in catalysis, optics, magnetic separation and magnetic resonance imaging contrast agents. However, the formation of nanohybrids (NHs) is usually difficult due to the incompatibility of components, especially for NHs of core‐shell structures with mismatched crystal lattices. In this study, NHs containing Ag core and CoFe alloy surface layer (Ag‐CoFe NHs) with varieties of hybrid structures were successfully synthesized by a sequenced microfluidic process. The hybrid structure formation mechanism was discussed according to the crystal plane matching theory, and their related optical and magnetic properties were investigated. When compared to Ag NPs, Ag‐CoFe NHs presented a distinct red shifted and broader absorption peak in visible region. This may be attributed to the changes in dielectric constant caused by different CoFe shells and the diversity of hybrid structures. Moreover, due to the interface pinning effects and magnetoelectric coupling effect between Ag cores and CoFe shells, the superparamagnetic properties of Ag‐CoFe NHs still existed at room temperature although its block temperature was much higher than that of CoFe NPs. Based on these characteristics, the Ag‐CoFe NHs show great potential in magneto‐optics, multi‐mode nanomedicines and other related fields.
An Initial Study on the Feasibility of Using Rudimentary SERS in Quick Chemical Assessment of Ambient Aerosols
Authors: Saniel Monica Blaise B. , Lim Len Herald V. , Lamorena Rheo B. 
Published: December 2019

AbstractA portable or field‐deployable Raman spectrometer was fabricated for ambient particulate matter chemical assessment. The Raman spectrometer was optimized using five organic compounds namely, naphthalene, ascorbic acid, oxalic acid, sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP), as general compositional classifiers. Compounds were deposited onto microscope glass slides and analyzed under varying laser power (30 mW – 200 mW) and integration time (3 s – 10s). Spectral data from the fabricated device were compared with that obtained from a benchtop reference device to verify correctness of spectral signature. Cu nanoparticles, as surface‐enhanced Raman Spectroscopy (SERS) substrates, were applied to the samples by direct dropping and drop‐coating. Results show that Raman intensity and signal to noise (S/N) ratio increases with increasing laser power and integration time. Results also show that the use of SERS technique amplified the Raman spectral signals of naphthalene and oxalic acid by 57% and 53.8%, respectively, in comparison to conventional Raman. Notably, no additional peaks were formed from the application of nanoparticles and only peak intensity amplification was observed.
Isolation and Bioactive Potential of Fucoidan from Marine Macroalgae Turbinaria conoides
Authors: Ganapathy Sivaranjani , Lingappa Sivakumar , Naidu Kavitha , Selvaraj Uthra , Ramachandiran Sivaramakrishnan , Ponnusamy Shanmugam , Somasundaram Somasundaram Thirugnanasambandam 
Published: December 2019

AbstractThe sulfated polysaccharide fucoidan was extracted from brown algae Turbinaria conoides using hot water and purified by anion‐exchange chromatography. The biochemical and monosaccharide composition of purified fucoidan was studied by colorimetric assays and Gas Chromatography Mass Spectrometry (GCMS). The purity of fucoidan was confirmed by agarose gel electrophoresis and the structure was characterized by using spectroscopic techniques such as Fourier transform infrared spectroscopy (FT‐IR) and solid‐state nuclear magnetic resonance (NMR) techniques. Further, the bioactivity properties of fucoidan such as antioxidant, anticoagulant and anti‐inflammatory were evaluated. The results showed profound antioxidant and anti‐inflammatory activities of fucoidan. The anti‐coagulant activity of fucoidan demonstrated striking inhibition of intrinsic and extrinsic coagulants involved in coagulation pathway.
Interaction Studies of Methanol and Ethanol Vapors on Green Phosphorene Sheets: A First‐Principles Study
Authors: Swetha Baswa , Nagarajan Veerappan , Chandiramouli Ramanathan 
Published: December 2019

AbstractThe electronic and adsorption properties of methanol & ethanol on green phosphorene nanosheets (GP‐NS) are explored using first‐principles studies. We confirmed the stable structure of GP‐NS using formation energy, which is recorded as −3.72 eV/atom. We studied the adsorption energy of methanol and ethanol vapors on GP‐NS that are noted to be exothermic. Also, the charge transfer shows that charge transfer takes place between alcohol molecules and GP‐NS. The semiconducting nature of GP‐NS is noticed from our calculation. The change in the energy gap is observed owing to the adsorption of the ethanol & methanol vapors on GP‐NS. The results of this report reveal that GP‐NS is a capable base substrate for detecting alcohol vapors. The present report will lay new in‐roads for the usage of GP‐NS as chemical sensor.
A Novel Class Substituted Imidazo[2,1‐b][1,3,4]thiadiazole Derivatives: Synthesis, Characterization, In Vitro Biological Activity, and Potential Inhibitors Design Studies
Authors: Er Mustafa , Ahmadov Farid , Karakurt Tuncay , Direkel Şahin , Tahtaci Hakan 
Published: December 2019

AbstractIn this study, imidazo[2,1‐b][1,3,4]thiadiazole derivatives were designed and synthesized. All of the synthesized compounds were characterized by 1H and 13C nuclear magnetic resonance (1H NMR and 13C NMR), fourier‐transform infrared spectroscopy (FT‐IR), elemental analysis, mass spectrometry, and X‐ray diffraction. The synthesized compounds were tested for antileishmanial activity against two Leishmania species and antibacterial activity against nine bacterial species in the study. It was observed that 2‐(4‐Fluorobenzylthio)‐6‐(4‐fluorophenyl)imidazo[2,1‐b][1,3,4]thiadiazole (5) had the highest antileishmanial activity (MIC: 625 μg/mL). Also, 4‐(2‐(4‐fluorobenzylthio)imidazo[2,1‐b][1,3,4]thiadiazol‐6‐yl)benzonitrile (10), 2‐(4‐fluorobenzylthio)‐6‐(4‐phenylphenyl)imidazo[2,1‐b][1,3,4]thiadiazole (11), and 4‐(2‐(4‐methoxybenzyl)imidazo[2,1‐b][1,3,4]thiadiazol‐6‐yl)benzonitrile (25) were found to be effective at different studied concentrations. PyRx software, which uses a Lamarckian genetics algorithm, was utilized to find the affinity values of all compounds in molecular docking simulations. Pharmacokinetic properties and toxicities of the ligands were then researched using PROTOX (a webserver for the prediction of oral toxicities of small molecules) and FAF‐Drugs (free adsorption distribution, metabolism, excretion (ADME) tox filtering tool). The study showed that the ligands had acceptable toxicity and ADME properties for the inhibition of the 3JUS receptor.
Electrochemical Methodology as an Useful Tool for the Interfacial Characterization of Aqueous Reverse Micelles
Authors: Cobo Solís Airam K. , Luna M. Alejandra , Falcone R. Darío , Correa N. Mariano , Molina Patricia G. 
Published: December 2019

AbstractIn this work, for the first time, the electrochemical behavior of hydroquinone (H2Q) by linear voltammetry in aqueous reverse micelles (RMs) of sodium 1,4‐bis(2‐ethylhexyl) sulfosuccinate (AOT)/n‐heptane, as well in homogenous media at different pH values, were studied. The choice of this molecular probe is because of its electrochemical response in water, strongly depend on the pH value thus, our goal is to know more about an intriguing issue in the soft matter field, what is the pH value for water encapsulated in the water pool of AOT RMs. Our work will demonstrate that the interfacial apparent pH value of AOT RMs is not strongly acidic as some of the literature works claim, but it is around a pH value of 6.7. Thus, through the electrochemistry technique, the present work reinforces the idea that the concept of is strongly dependent on the water‐interface interactions and the molecular probe location.
“Quinoline Consists of 1H‐1,2,3‐Triazole Hybrids: Design, Synthesis and Anticancer Evaluation”
Authors: Venkata Sivarami Reddy Gangireddy , C.Narkhede Umesh , Jadhav Vinod. D , Naidu Challa Gangu , Addada Ramakrishnam Raju , Pulya Sravani , Ghosh Balaram 
Published: December 2019

AbstractA series of novel 8‐bromo‐1H‐1,2,3‐triazol‐4‐yl‐2‐methylquinoline derivatives and their Suzuki coupling products were synthesized via Copper catalyzed azide‐alkyne cycloaddition (CuAAC) strategy followed by microwave assisted Suzuki coupling for the development of new series of anticancer agents. The invitro anticancer activity of the synthesized compounds were screened against human breast cancer (MDA‐MB‐231) and melanoma cell lines (B16F10). Among these, compounds 5 c (Azetidine), 5 e (Nitro benzoate), 5 f (fluorobenzyl)‐1H‐pyrazole), 5 g (Boc piperidine), 6 a (cyclo propyl), 6 c (5‐fluoro‐6‐methoxypyridin‐3‐yl)and 6 d (2‐methoxypyridin‐3‐yl) were showed anticancer activity ranging from 13.44 μM to 38.2 μM. The cellular toxicity of the novel compounds was also evaluated using normal human embryonic kidney (HEK) cell lines.
Synthesis, Photophysical, Thermal and Crystallographic Studies of 3‐Aminocoumarin Based Monobasic κ3‐O,N,O‐tridentate/ κ2‐N,O‐bidentate Schiff Base Divalent Complexes
Authors: Verma Sanjay K , Savani Chirag , Singh Vinay K. 
Published: December 2019

AbstractThe reaction of 3‐Amino coumarin based Schiff base ligands HL1 and HL2 with metal acetates in refluxing ethanol affords access to a new series of neutral mononuclear divalent complexes [MII‐κ3‐bis‐O,N,O‐tridentate Schiff base‐ HL1/ HL2] {HL1, MII=Co (1), Ni (2) or Zn (3); HL2, MII=Co (4), Ni (5) or Zn (6)}, [CuII‐κ2‐bis‐N,O‐bidentate Schiff base‐HL1] (7) and [CuII‐κ2‐bis‐N,O‐bidentate Schiff base‐HL2] (8). Compounds were characterized by microanalysis, standard spectroscopic (viz. MALDI‐TOF‐MS, IR, 1H and 13C NMR, UV‐visible absorption and emission) and TGA/DTA methods. The unambiguous crystal structure of HL1, HL2, complexes 2 and 3 was determined crystallographically. The IR, UV‐visible, EPR spectral and magnetic studies clearly suggest the κ3‐O,N,O‐tridentate‐ coordination mode of HL1 and HL2 towards cobalt(II), nickel(II) and zinc(II) metal ions in 1–6 and κ2‐N,O‐bidentate‐coordination mode towards copper(II) metal ions in 7 and 8. Notably, compounds fluoresce a medium to strong emissions in the visible region is observed with concomitant Stokes shifts of ≈ 90 nm. UV‐visible transmittance spectral study reveals the semiconducting nature of HL1, HL2, complexes 1–8 gave with band gap energy of 1.57‐2.24 electron volts. The molecules of HL1, HL2, 2 and 3 are stabilized by various intermolecular CH…π, CH…O and π…π contacts that efficiently managed the growth of self‐assembly in three dimensions and form infinite molecular layers in the solid state.
Enhancing the Electrochromic Properties of Polyaniline through Incorporating Terpyridine Units and Coordination Bonding with Transition Metal Ions
Authors: Xiong Shanxin , Zhang Jiaojiao , Wang Ru , Wu Bohua , Chu Jia , Wang Xiaoqin , Zhang Runlan , Gong Ming , Li Zhen , Qu Mengnan , Chen Zhenming 
Published: December 2019

AbstractA novel polyaniline‐terpyridine‐transition metal ions (PANI‐TPY−M (M=Fe (II), Co (II), Ni (II))) hybrid electrochromic materials containing coordination bonds were successfully synthesized in an aqueous medium. The molecular and aggregation structures of PANI‐TPY−M were systematically studied by FTIR (Fourier transform infrared spectroscopy), particle size analysis and Raman spectroscopy. The influence of transition metal ions on the thermal stability of materials was analyzed by TGA (thermogravimetric analysis). The electrochemical behaviors and electrochromic properties of materials were measured by CV (cyclic voltammetry) and UV‐vis (UV‐visible spectroscopy). It can be found that the electrochemical activities of PANI‐TPY and PANI‐TPY−M are both higher than that of PANI. Especially, the electrochromic devices with PANI‐TPY−M (M=Fe (II), Co (II), Ni (II)) as active layer exhibit obvious optical contrast enhancement function. As comparison to PANI, the contrast of PANI‐TPY increases about 57%, the contrast of PANI‐TPY−Fe increases about 76%, the contrast of PANI‐TPY−Co increases by nearly 73%, and the contrast of PANI‐TPY−Ni increases by 54%.
Fabrication of Ti3+ Self‐doped TiO2 via a Facile Carbothermal Reduction with Enhanced Photodegradation Activities
Authors: Wang Yan , Sun Liping , Chudal Lalit , Pandey Nil Kanatha , Zhang Manbo , Chen Wei 
Published: December 2019

AbstractHerein, we report a new and facile carbothermal reduction method to prepare Ti3+ self‐doped titanium dioxide (TiO2) using inorganic carbon powder as a reducing agent. As‐prepared samples were thoroughly characterized by XRD, Raman, SEM, UV‐DRS, EPR, XPS, and BET. The photocatalytic activity of the as‐prepared nanomaterials was explored using the degradation of Rhodamine B (RhB) under Xe light illumination. The self‐doped TiO2 (TiO2‐C0.5‐600) exhibits high photodegradation activity with the degradation efficiency of 97% in 120 min. The improved performance could be because of the separation of photogenerated carriers and the narrowing of band gap due to the introduction of Ti3+ and oxygen vacancy. Overall, our work demonstrates a simple, environmentally friendly, and economical synthesis method for narrowing the band gap and developing a highly photocatalytic material, thereby opening a new avenue in the field of wastewater treatment.
Multifunctional Carbon Dots for Trace Water Detection, White LEDs, and Bioimaging
Authors: Geng Bijiang , Wang Xulong , Li Ping , Shen Wenwen , Qin Hua , Fang Fuling , Yin Luqiao , Shen Longxiang , Pan Dengyu 
Published: December 2019

AbstractHighly fluorescent, ultrafine CDs were synthesized by a simple one‐pot solvothermal method. The as‐prepared CDs exhibited unique yellow emission and intrinsic fluorescence characteristics independent of excitation wavelengths. We revealed a distinct fluorescence quenching mechanism in the CDs, where the reversible alternation between aggregation and dispersion states can mediate the fluorescence turn‐on and turn‐off response. Therefore, the CDs can be used as a fluorescence nanoswitch for the highly sensitive quantitative detection of trace water in organic solvents. We also demonstrated the applications of the CDs as a stable yellow phosphor and biological probe for white LEDs and biomembrane imaging. Our results suggest that the low‐cost fluorescent material has great promise for practice applications in sensing, bioimaging, and optoelectronic device.
Chemo‐ and Diastereoselective Synthesis of Pyrazolo‐tetrahydropyridines via Multicomponent Sequential Aza‐Diels‐Alder Reactions in Water
Authors: Nazeri Mohammad Taghi , Javanbakht Siamak , Shaabani Ahmad , Khavasi Hamid Reza 
Published: December 2019

AbstractIn this study, we report a novel and an efficient strategy for the synthesis of chemo‐ and diastereoselective synthesis of pyrazolo‐tetrahydropyridines via a one‐pot multi‐component intramolecular Aza‐Diels–Alder reactions (ADARs) from benzoylacetonitrile derivatives, phenylhydrazine, salicylaldehyde derivatives, and styrenesulfonyl or cinnamoyl chloride in H2O as a green solvent. This synthesis procedure was also designed to follow the group‐assisted purification (GAP) chemistry, which can avoid traditional purification such as recrystallization and chromatography methods.