bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrathin Silica‐Coated Iron Oxide Nanoparticles: Size‐Property Correlation
Authors: Gupta Pranshu K. , Dravid Vinayak P. , De Mrinmoy 
Published: August 2020

AbstractMagnetic nanostructures (MNS) in their superparamagnetic form are promising materials systems for contrast enhancement in magnetic resonance imaging (MRI) and thermal‐activation therapeutics via RF heating. These biomedical applications and associated properties are very much dependent on the structure, composition and size/shape of MNS. Although there are many speculations on the effect of various parameters on MNS, the size dependent properties are not well understood, largely due to challenges in size‐selective large‐scale synthesis for precise measurements and interference from typical large surface coating. Herein we report the size effect of iron oxide MNS on hydrodynamic radius, zeta potential, magnetic property and relaxivity. For this study, we have synthesized a wide range of monodispersed iron oxide MNS, from 7 nm to 20 nm nominal size and phase transferred to aqueous media with very thin layer of silica coating using Polyhedral Oligomeric Selesquioxanes (POSS). The dynamic light scattering (DLS) study and zeta potential measurement were carried out to determine the hydrodynamic radius and surface charges. The hydrodynamic radius follow the linear correlation but the zeta potential does not maintain it due to nonlinear mass/charge ratio relations with varying size. We have also conducted correlative studies of magnetic saturation (Ms) and
relaxivities. This work will highlight the size dependent correlation and tailoring of MNS properties for desired biomedical applications.
One‐Step Synthesis of Solid‐State Photoluminescent Carbon Nanodots from Grains for Latent Fingerprint Detection
Authors: Wang Yaping , Ju Wei , Chen Jianjun , Liu Ziying , Wang Jianshe 
Published: August 2020

AbstractEmploying grains (wheat, corn, sorghum and rice) as precursors, a series of carbon nanodots (CDs) have been prepared via one‐step hydrothermal treatment. All the CDs have narrow size distribution, roughly spherical shape and similar optical properties. The size depends on the precursors, which varies from 2 to 25 nm. The CDs without further treatment can overcome aggregation‐induced quenching effect, and emit stable bright blue luminescence under UV light irradiation in both colloidal and solid states. Additionally, the mechanism for the solid‐state fluorescence of CDs was also explored. Moreover, the feasibility of CDs as fluorescent labels for latent fingerprint detection was investigated and the results demonstrate well‐defined papillary ridges with higher sensitivity and wider applicability. The work provides a simple, low‐cost, and promising alternative for latent fingerprint detection in forensic science.
A Molecular Dynamics Study of the Inhibition of Monomeric HIV‐1 Protease as An Alternative to Overcome Drug Resistance by RNA Aptamers as A Therapeutic Tool
Authors: Ajamgard Marzieh , Sardroodi Jaber Jahanbin , Ebrahimzadeh Alireza Rastkar 
Published: August 2020

AbstractHere, the interaction of three aptamers with HIV‐1 protease was investigated with the help of molecular dynamics simulations. These simulations led to precise structural and energetic results. The sequencing of the considered aptamers was AP1 as the aptamer number 1: (CUUCAUUGUAACUUCUCAUAAUUUCCCGAGGCUUUUACUUUCGGGGUCCU), AP2 as the aptamer number 2: (CCGGGUCGUCCCCUACGGGGACUAAAGACUGUGUCCAACCGCCCUCGCCU), and AP3 as the aptamer number 3: (C, U, A, G and UU nucleotides of AP1 were replaced with A, G, G, A and C to yield AP3). The results of molecular dynamics simulations showed that aptamers 2 and 3 were good alternatives to interact with the protease enzyme and to control this enzyme; however, in AP2 the results were somehow improved. The results of MM‐PBSA showed that although the aptamer 3 as a mutant aptamer had a good affinity with the protease enzyme, as compared to the aptamer 1, by impairing dimerization, it disrupted its structural stability and function. However, the results also indicated that the aptamer 2 could be a better inhibitor because it would cause a more severe conformational change in the structure of the enzyme.
Influence of Flame Retardants on LLDPE‐Date Pit Fiber Composites: Thermal Degradation and Tensile Properties
Authors: Gulati Kapil , Lal Sohan , Kumar Manish , Arora Sanjiv 
Published: August 2020

AbstractLinear low density polyethylene (LLDPE)‐date pit composites incorporated with different flame retardants were synthesized by extrusion and casted into shape by injection moulding. Several additive type flame retardants viz. Ammonium polyphosphate (APP), Melamine phosphate (MP), Ammonium dihydrogen orthophosphate (ADOP), Diammonium hydrogen phosphate (DAHP) were added to enhance the flame retarding behaviour of composites. The thermal analysis and mechanical properties of composites have also been investigated. Thermogravimetric analysis (TGA) revealed a two step degradation mechanism of all the blends. The kinetic parameters such as activation energy and differential conversion function f(ɑ) were evaluated using three different non isothermal methods based on the iso conversional plots: Friedman (FM), Ozawa‐Flynn‐Wall (OFW) and Coats‐Redfern (Modified). The average value of activation energy of thermal degradation of blends evaluated using Friedman method; was used to depict the actual mechanism of degradation by fabricating the Criado's master plot. Addition of any kind of flame retardant led to an improvement in both tensile as well as flexural strength of composites. According to the results of Limiting Oxygen Index (LOI) and UL‐94 testing, addition of APP led to the significant improvement in the flame retardancy of LLDPE composites.
Fabrication and Analysis of ZnO Quantum Dots Based Easy Clean Coating: A Combined Theoretical and Experimental Investigation
Authors: Sethi Sushanta K. , Kadian Sachin , Anubhav  , Goel  , Chauhan Rishi Pal , Manik Gaurav 
Published: August 2020

AbstractIn this work, ZnO QD have been synthesized and later characterized using Transmission Electron Microscope (TEM) and X‐ray diffraction (XRD). XRD has confirmed the crystalline structure and TEM provided an average particle size of ∼6 nm. Further, ZnO QD with different wt. % were incorporated into poly(vinylacetate)‐graft‐poly(dimethylsiloxane) (PVAc‐g‐PDMS) base matrix and several performance properties like water contact angle (CA), transparency and surface behavior were assessed. Molecular dynamics simulation helped to demonstrate that vdW and valence energy effectively control filler‐matrix interactions and ZnO QD filler significantly enhanced matrix‐substrate interaction. For this, Gaussian distribution function has been utilized to model surface roughness of PVAc‐g‐PDMS/ZnO coatings with randomized filler dispersion. Experimentally, scanning electron microscope (SEM) confirmed the presence of dual (micro and nano) scale grooves by ZnO QD alone due to their limited agglomeration, which helped to enhance water repellency by ∼16 % without compromising with transparency. Theoretical investigations reveal that the coating, formulated from non‐health hazardous materials, possessed good transparency (>88 %), substrate adhesion (‐4045.33 kcal/mol), water (CA=109±2°) and decent oil (CA=69±2°) repellency, which agrees well with experimental results. Conclusively, 3 % ZnO QD in PVAc‐g‐PDMS is a useful coating material with optimal substrate adhesion, transparency and fluid repellency.
Encapsulation of Docetaxel into Diblock Polymeric Polymersome as a Nanodrug
Authors: Haghshenas Venus , Sariri Reyhaneh , Naderi Sohi Alireza , Nazari Hojjatollah 
Published: August 2020

AbstractIn this study, a chemotherapeutic drug, Docetaxel (DTX) was loaded in a di‐block polymeric nanoparticles (NPs) consisted of Oleate and Poly (ethylene glycol). First, the OA‐PEG1000 units were synthesized by the esterification reaction and confirmed by 1HNMR and FTIR spectroscopies. After determination of critical micelle concentration (CMC), the DTX was loaded into the OA‐PEG1000 NPs using the solvent displacement method. The encapsulation efficiency and loading capacity percentages were estimated as 22.2 % and 0.43 % respectively. The average size (obtained by DLS) and zeta potential of NPs were as 221.3±8.06 nm and 6.31±0.29 mV respectively indicating polymersome formation. The morphology of NPs in AFM images was almost spherical with a diameter of about 207.1±28.36 nm which was approximate to DLS outcomes. These results demonstrated that di‐block polymeric NPs can be potentially practical for carrying and delivering DTX as a novel anticancer pharmaceutical.
Green EmittingCe3+/ Tb3+‐Doped BaF2 Nanocrystals and Their Impact on Skeletal Muscle of Developing Zebrafish Larvae
Authors: Sharma Rahul Kumar , Chouryal Yogendra Nath , Nema Shubham , Nigam Sandeep , Bera Siba Prasad , Bhargava Yogesh , Ghosh Pushpal 
Published: August 2020

AbstractAn ionic liquid (IL)‐based solvothermal method is employed to prepare single‐phase, luminescent, cubic rare‐earth doped and silica‐coated BaF2 nanomaterials. High energy transfer efficiency (∼60%) from Ce3+ to Tb3+ for BaF2:Ce3+/Tb3+ nanoparticles dispersed in DMSO solution is observed. Furthermore, for the first time to the best of our knowledge, as‐prepared RE ion/s doped and silica‐coated BaF2 nanoparticles are used for the toxicological assessment on live zebrafish larvae. Interestingly, static exposure of these nanoparticles from 6 hpf till 96 hpf period at high concentration (70 mg/L) do not show any developmental anomalies as judged by bright‐field and birefringence optical imaging method which promises its large‐scale applications in imaging and other biological purposes.However, as a positive control, cypermethrin‐based pesticide could induce developmental defects at 0.1 mg/L concentration. It is worth mentioning that the concentration of BaF2 nanoparticles chosen in present study is much higher than the other nanoparticles reported so far.
Synthesis and Luminescent Properties of Functionalized Bipyridyl Based Eu Complexes
Authors: Krinochkin Alexey P. , Kopchuk Dmitry S. , Kim Grigory A. , Shevyrin Vadim A. , Tseitler Tatyana A. , Santra Sougata , Kovalev Igor S. , Zyryanov Grigory V. , Rusinov Vladimir L. , Chupakhin Oleg N. 
Published: August 2020

Abstract5‐(4‐(Het)arylphenyl)‐2,2′‐bipyridine‐6‐carboxylic acids were synthesized as ligands for the neutral lanthanide complexes by using the “1,2,4‐triazine” approach and Suzuki or Stille cross‐coupling reaction with intermediate 5‐(4‐bromophenyl)‐2,2′‐bipyridine‐6‐carbonitrile. The neutral europium complexes of these ligands were obtained with 3 : 1 stoichiometric amount. The photophysical properties of the synthesized complexes were studied, and the influence of the nature of the aryl substituent was estimated. In some cases the improvement of the photophysical characteristics has been demonstrated for the complexes in case of addition of extra phenyl ring in the structure of the ligand.
Claisen‐Schmidt Condensation using Green Catalytic Processes: A Critical Review
Authors: Yadav Ganapati D. , Wagh Dipti P. 
Published: August 2020

AbstractClaisen‐Schmidt condensation have historical significance for over140 years and the scope was expanded due to the realization that chalcones so synthesized possess biological activity. The principles of green chemistry with emphasis on use of different solid catalysts with proper distribution of active centers such as acid, base, acid‐base, organo‐ were used along with solvent‐less systems. Among solid bases layered double hydroxides (LDH)/hydrotalcites are the most common. The limitations of solid bases are overcome by solid acids and superacids. A number of metal oxide supports are used. MOFs are increasingly being used. Complex organo‐catalysts are employed for getting excellent regio‐selectivity. In certain metal oxides, both acidic and basic sites co‐exist on the pore surface of catalyst which offer superior results. Synergism of solid catalysis using microwaves and ultrasound to intensify rates and selectivity is in vogue.Controlled pore structure and distribution of active catalytic centers, whether mono‐, bi‐ or tri‐functional catalysts, will give better green and smart processes. The review gives a critical analysis of the area and presents future directions for research.
A New Aliphatic Ketone, Chemical Composition, Antibacterial, Antioxidant and In Vitro Cytotoxic Activities of Lepidium latifolium
Authors: Feng Yan , Assani Israa , Wang Chun‐Gu , Hou Pei‐Lei , Zhao Shi‐Feng , Ye Hao‐Jie , Li Rui‐Chen , Zhang Jin‐Bin , Liao Zhi‐Xin 
Published: August 2020

AbstractOne new aliphatic ketone alcohol, 15,17‐dione‐16‐hentriacontanol (1), with fifteen known compounds (2–16) were isolated from the ethanolic extract of the whole dried plant of Lepidium latifolium. The antibacterial activities (using minimum inhibitory concentrations (MIC) detection method), the antioxidant activities (using 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH) and pyrogallol), and the antiproliferative activities (using 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) method) against three human cancer cell lines were evaluated. The results showed that compounds 2, 9, 10 and 11 with phenolic hydroxyl groups have good antibacterial and DPPH scavenging activities. Compounds 2, 12 and 13, which contain ‐NH groups have the highest scavenging rates of superoxide anions. The compounds of long‐chain alkane containing hydroxyl groups have potent inhibitory activity against MGC‐803, HepG2 and T24 cancer cells. The experimental content of this paper enriches the related research of L. latifolium, and greatly expands the market application value of the plant.
Novel and Green Preparation of Fe3O4@TiO2‐Immobilized‐ILs Based on DABCO for Highly Efficient Synthesis of Primido[4,5‐d]pyrimidines
Authors: Ghasemzadeh Mohammad Ali , Bakhshali‐Dehkordi Raziyeh 
Published: August 2020

AbstractRecently, ionic liquids immobilized on magnetic nanoparticles (MNPs) have drawn increasing attentions in organic synthesis and separation technologies and gained substantial progresses. In this study, the Fe3O4@TiO2@ILs nanocatalyst was first synthesized and characterized by using techniques such as Fourier transform infrared spectroscopy (FT‐IR), energy‐dispersive X‐ray (EDX), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FE‐SEM), powder X‐ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The efficiency of the nanocatalyst was investigated in the preparation of pyrimido[4,5‐d]pyrimidine derivatives under solvent‐free conditions. The nanocatalyst demonstrated excellent catalytic activity and the products were synthesized in good to excellent yields. Moreover, the recoverability and reusability of the catalyst were investigated to show the effect of ionic liquid moieties on the stabilization of Fe3O4@TiO2@ILs species during the reactions. Our study showed that the nanocatalyst could be recovered and reused at least seven times without any appreciable decrease in activity which confirmed its high efficiency and high stability under the reaction conditions.
Theoretical Study of VX Hydrolysis Mechanism Catalyzed by Phosphotriesterase Mutant H254R
Authors: Zheng Yong‐Chao , Su Jing‐Xuan , Zheng He , Li Sheng‐Song , Zhao Chong‐Lin , Chen Li‐Kun , Zhong Jin‐Yi , Chen Shi‐Lu 
Published: August 2020

AbstractPhosphotriesterase (PTE) is a bacterial enzyme that can catalyze the hydrolysis of V‐type chemical warfare nerve agents. Herein, the hydrolysis mechanism of VX analogs catalyzed by the H254R PTE mutant, in which the histidine 254 residue is replaced by an arginine, has been investigated using the hybrid density functional theory method B3LYP. The chemical model of the active site of H254R PTE mutant was constructed based on the high resolution X‐ray crystal structure. We have presented the energetics and the characterization of stationary points in the catalytic reaction. The calculations indicate that the catalytic process contain two SN2 displacement steps and the step of hydroxide regeneration is rate‐limiting with an overall barrier of 22.2 kcal/mol. The Arg254 plays an important role as a proton donor/acceptor for protonating leaving group and activating water molecule. Moreover, the H254R PTE mutant with binuclear cobalt center turns out to higher activity towards VX than the binuclear zinc H254R PTE.
Metal‐Free, H2O2‐Mediated, Regioselective Direct C‐3 Hydroxylation of Imidazo[1,2‐a]pyridines via C(sp2)‐H Bond Functionalization
Authors: Kant Yadav Ravi , Kumar Yogesh , Chaudhary Sandeep 
Published: August 2020

AbstractFor the first time, a new, cost‐effective, metal‐free, H2O2 (50 % in water)‐mediated regioselective direct C‐3 hydroxylation of imidazo[1,2‐a]pyridines via C‐H bond functionalization is reported. This metal‐free C(sp2)‐O bond formation protocol is operationally simple and showed broad range of functional group tolerance and substrate affinity. To the best of our knowledge, this is the first report of imidazo[1,2‐a]pyridine‐3‐ols showing promising in vitro antioxidant activity.
Poisoning Effect Comparison of ZnCl2 and ZnSO4 on Mn‐Ce/AC Catalyst for Low‐Temperature SCR of NO
Authors: Su Zenghui , Ren Shan , Yang Jie , Yao Lu , Zhou Yuhan , Chen Zhichao , Zhang Tianshi 
Published: August 2020

AbstractIn this study, the effect of different zinc salts (ZnCl2 and ZnSO4) on the deactivation of activated carbon(AC)‐based Mn−Ce catalysts and the poisoning mechanism of zinc salts on Mn−Ce/AC are comparatively studied. SEM, BET, XRD, XPS, H2‐TPR, NH3‐TPD and In‐situ DRIFT are used to characterize the physical and chemical changes of Mn−Ce/AC catalyst. The Selective Catalytic Reduction (SCR) activities of Mn−Ce/AC has a noticeable decline after loading zinc salts, and the highest NO conversion of Zn poisoning catalysts do not exceed 70 %. And the acid site is occupied by Zn2+ on the catalyst, which affects the chemical adsorption of NH3 and hinders the formation of the intermediate ‐NH2. Moreover, the decrease of Mn4+, reducibility of manganese oxide and acid sites are more serious on ZnC−Mn‐Ce/AC. Besides, loading ZnSO4 can improve the content of Ce3+ and Oβ on catalyst surface, which can mitigate the poisoning effects of ZnSO4 on Mn−Ce/AC catalyst. Hence, ZnCl2 displays a more serious poisoning effect on Mn−Ce/AC catalyst compared with ZnSO4. Then the probable mechanism model of ZnCl2 and ZnSO4 on Mn−Ce /AC catalyst is proposed and compared.
A Practical Synthesis of 3‐Functionalized Coumarins from o‐Cresols and Active Methylene Compounds under Metal and Catalyst‐Free Conditions Using tert‐Butyl Hydrogen Peroxide
Authors: Chauhan Swati , Verma Pratibha , Kandasamy Jeyakumar , Srivastava Vandana 
Published: August 2020

AbstractAn efficient synthesis of 3‐functionalized coumarins is demonstrated from o‐cresols and active methylene compounds under solvent‐, metal‐ and catalyst‐free conditions in the presence of 70 % aqueous tert‐butyl hydrogen peroxide. The important features of this protocol are operational simplicity, mild reaction conditions and good to excellent yield of the products.
Modification of Molecular Sieves USY and Their Application in the Alkylation Reaction of Benzene with Cyclohexene
Authors: Meng Fanfei , Ding Yuansheng , Meng Wei , Mi Guangyi , Qiu Jun 
Published: August 2020

AbstractIn this manuscript, ultrastable Y (USY) zeolites are modified employing a liquid‐phase ion exchange method to furnish H‐USY with different properties. Modified with ammonium nitrate, H‐USY could largely improve the conversion in the alkylation reaction of benzene with cyclohexene due to the increase in Brunauer‐Emmett‐Teller (BET) specific surface area, Barrett‐Joyner‐Halenda (BJH) pore volume, BJH pore size, and acidity of H‐USY. Catalyzed by the molecular sieve modified twice with ammonium nitrate, this alkylation reaction demonstrated a 95.3 % conversion of cyclohexene with 97.4 % selectivity of cyclohexylbenzene. And we found that urea‐modified USY has the similar effect, a 96.1 % conversion of cyclohexene with slightly 94.9 % selectivity of cyclohexylbenzene.
Application of Palladium Based Precatalytic Systems in the Suzuki‐Miyaura Cross‐Coupling Reactions of Chloro‐ Heterocycles
Authors: Bhaskaran Savitha , Padusha M. Syed Ali , Sajith Ayyiliath M 
Published: August 2020

AbstractCarbon‐Carbon bond forming reactions using Suzuki‐Miyaura cross‐coupling (SMC) technology to construct aryl‐aryl, aryl‐heteroaryl or heteroaryl‐heteroaryl linkages continues to play a vital role in pharmaceuticals, agrochemicals, material science and manufacturing fields. The importance of Suzuki‐Miyaura cross‐coupling which is also reflected in their use in industrial applications, warrants the development of highly efficient catalytic systems that allows the cross‐coupling of economically attractive heteroaryl chlorides. Conversely, the low reactivity of heteroaryl chlorides followed by problems associated with multi‐heteroatom systems amplifies the difficulties involved in SMC procedures. This review focuses on the developments made in the palladium mediated SMC of chloro heterocycles using various palladium/Ligand combinations and highlights the significant improvements achieved by the use of Buchwald's palladium precatalysts.
High Cycling Performance Li‐S Battery via Fenugreek Gum Binder Through Chemical Bonding of the Binder with Polysulfides in Nanosulfur@CNFs Cathode
Authors: Mo Yu‐Xue , Wu Yi‐Jin , Yin Zu‐Wei , Ren Wen‐Feng , Gao Zhen‐Guang , Zhang Peng‐Fang , Lin Jin‐Xia , Zhou Yao , Li Jun‐Tao , Huang Ling , Sun Shi‐Gang 
Published: August 2020

AbstractThe dissolution and diffusion of lithium polysulfides are one of the main intrinsic bottlenecks in the development of lithium‐sulfur (Li−S) batteries with long term cycling stability. Appropriate binders could play a key role of anchoring the lithium polysulfides in S‐cathode through strong chemical bonds, thus boosts the electrochemical performance of Li−S battery. Herein, we report a new binder (fenugreek gum, FG) that has enhanced significantly the cycling performance of Li−S batteries with S@CNFs composite as cathode. The Li−S cell with FG binder delivers a large initial capacity of 900 mAh g−1 at 2 C, and a reversible capacity retention of 45.6 % after 1300 cycles, superior to the cycling performance of Li−S cell with conventional PVDF or previous reported guar gum (GG) binder. This enhancement in cycling performance of Li−S batteries could be attributed to the formation of the S−O and Li−O bonds between the O‐relevant functional groups in the binder and the polysulfides in S‐cathode as manifested by XPS data of the discharged and charged electrodes. Furthermore, the tensile strain rate of the FG binder is as high as 32 %, which can effectively restrain the volume expansion of the S‐cathode during the discharge/charge process and ensure the integrity of the electrode.