A Review Featuring Fabrication,Properties and Applications of Carbon Nanotubes (CNTs) Reinforced Polymer and Epoxy Nanocomposites

Carbon nanotubes (CNTs) have long been recognized as the stiffest and strongest man-made material known to date.In addition,their high electrical conductivity has roused interest in the areas of electrical appliances and communication related applications.However,due to their miniature size,the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers.In order to enhance their chemical affinity to engineering polymer matrices,chemical modification of the graphitic sidewalls and tips is necessary.The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in this attempt to facilitate progress in this emerging area.Recently,carbonaceous nano-fillers such as graphene and carbon nanotubes (CNTs) play a promising role due to their better structural and functional properties and broad range of applications in every field.Since CNTs usually form stabilized bundles due to van der Waals interactions,they are extremely difficult to disperse and align in a polymer matrix.The biggest issues in the preparation of CNTs reinforced composites reside in efficient dispersion of CNTs into a polymer matrix,the assessment of the dispersion,and the alignment and control of the CNTs in the matrix.An overview of various CNT functionalization methods is given.In particular,CNT functionalization using click chemistry and the preparation of CNT composites employing hyperbranched polymers are stressed as potential techniques to achieve good CNT dispersion.In addition,discussions on mechanical,thermal,electrical,electrochemical and applications ofpolymer/CNT composites are also included.     

Rapid Aqueous Late‐Stage Radiolabelling of [GaF3(BnMe2‐tacn)] by 18F/19F Isotopic Exchange: Towards New PET Imaging Probes

A simple and rapid method for ¹⁸F radiolabelling of [GaF₃(BnMe₂‐tacn)] by ¹⁸F/¹⁹F isotopic exchange is described. The use of MeCN/H₂O or EtOH/H₂O (75:25) and aqueous [¹⁸F]F^? (up to 200 MBq) with heating (80 °C, 10 min) gave 66±4 % ¹⁸F incorporation at a concentration of 268 nm , and 37±5 % ¹⁸F incorporation at even lower concentration (27 nm ), without the need for a Lewis acid promoter. A solid‐phase extraction method was established to give [Ga¹⁸F¹⁹F₂(BnMe₂‐tacn)] in 99 % radiochemical purity in an EtOH/H₂O mixture.     

Depolymerization Study of Pakistani Coal in a Hydrogen Atmosphere. Effect of Operating Conditions

A Pakistani coal was de‐polymerized/liquefied in toluene in a 1000 mL micro autoclave. Experiments have been performed in a pool of hydrogen under varying operating conditions of temperature, residence time, hydrogen pressure (cold), coal/solvent ratio and coal particle size. A pronounced effect of all these process variables has been noted on the yields of liquefied products, i.e., THF solubles, n‐pentane solubles, and n‐pentane insolubles. Extraction temperature of 450 °C, residence time of 1 hour, hydrogen pressure of 30 kgf/cm², coal/solvent ratio of 1:2 and coal particle size of 53–45 μm were found optimum for maximum conversion of Pakistani coal into liquefied products.     

A New Irregular Trihydroxy Sesquiterpene from Teucrium mascatense

A new trihydroxy sesquiterpene, rel‐(1R,4aR,5S,6S,7S,8aR)‐decahydro‐6,8a‐dimethyl‐5‐(propan‐2‐yl)naphthalene‐1,6,7‐triol ( 1 ), has been isolated as a result of the phytochemical investigation on the CH₂Cl₂ extract of Teucrium mascatense. The structure elucidation of the new constituent was carried out by the combined use of 1D‐ (¹H‐ and ¹³C‐NMR) and 2D‐NMR (HMBC and HSQC) spectroscopic analysis, along with mass spectrometric techniques. In addition to the new constituent 1 , the known metabolite 2 , previously isolated from Crataegus pinnatifida, was also identified.     

Tailoring the donor moieties in TPA-based organic dyes for efficient photovoltaic,optical and nonlinear optical response properties

The current study reports tailoring the electronic donor structures of organic dyes to modify their optical and nonlinear optical (NLO) response properties. Five (5) tri-phenyl amine (TPA) based Donor-π-Acceptor (D-π-A) organic dyes with the codes ICAA1 , ICAA2 , ICAA3 , ICAA4 , and ICAA5 were designed and investigated for their optical and NLO properties using quantum chemical methods. Optical and NLO properties of these dyes were studied by CAM-B3LYP method and 6-311G* basis set. The focus has been on the impact of adding secondary donors and shifting their substitutions at ortho (o), meta (m) and para (p) positions. Among all designed compounds, ICAA4 showed the highest amplitude of average third-order NLO polarizability <γ>, which is calculated to be 1316 × 10⁻³⁶ esu. Time-dependent Density Functional Theory (TD-DFT) method was used to determine how a change in the position of the donor affected the excitation energy (E_g) and NLO response properties. The findings showed that changing the position of the secondary donor results in a red shift among absorption spectra as well as the increase in their NLO responses. Complete process of intramolecular charge transfer (ICT) has been investigated in terms of different optical parameters such as frontier molecular orbitals (FMOs), molecular electrostatic potentials (MEPs), transition density matrix (TDMs), density of states (DOS), electron density difference (EDD), and natural bond orbital (NBO) analysis. Our calculations for study of ICT process indicate that p-position of methoxy group performs better among all other positions and even it has better NLO response properties than the compound with three collective methoxy groups. The calculated V_oc values of all designed molecules range from 1.09 to 1.30, all of them are positive while their ΔG_inject is found to be in the range of −0.87 to −1.79 eV indicating their decent potential for photovoltaic applications. The studied optical, NLO and photovoltaic parameters illustrated that ICAA1 to ICAA5 are appropriate molecules not only for NLO applications but also for efficient photovoltaic purposes.     

Effect of Aging on the Physico Chemical Properties of Glass Fiber under Different Environmental Conditions

Glass fibers were characterized for physical and chemical changes before and after subjecting to aging under different environmental conditions. The conditions selected were: low temperature, outdoor atmosphere, indoor atmosphere, chemical environment, 95% humidity & water soaking treatment. The results show that glass fiber is a good candidate to resist sunlight, corrosive atmosphere, low temperature and shady atmosphere. The influence of prolonged time exposure to water caused a detrimental effect on the properties of the glass fiber. Hence, prolonged exposure to water should be avoided for the integrity of the glass fiber under study.     

乳液催化剂存在下空气辅助甲酸氧化法使油品脱硫(英文)

Catalytic oxidative desulfurization(ODS) of model oil and commercial oil samples was investigated using an air-assisted performic acid oxidation system with a phase transfer or emulsion catalyst comprising a quaternary ammonium salt-based heteropolyoxometalate.Different emulsion catalysts with a Keggin type heteroployoxometalate anion(containing W,Mo,and V) and cetyltrimethylammonium bromide cation were prepared and characterized by X-ray fluorescence,Fourier transform infrared spectroscopy,and scanning electron microscopy.[C16H33N(CH3)3]3[PW9Mo3O40] was the most effective catalyst in the current oxidation system,which reduced the sulfur content of the model oil from 1275 μg/g to 57 μg/g.The reactivity order of different model sulfur compounds was thiophene < dibenzothiophene < 4,6-dimethyldibenzothiophene. The ODS of model sulfur compounds followed first order kinetics with apparent activation energy from 29 to 27 kJ/mol.The catalysts also performed efficiently in the ODS of the industrial oil samples,including untreated naphtha,light gas oil,heavy gas oil,and Athabasca oil sands derived bitumen,for which sulfur removal rates were 83%,85%,68% and 64%,respectively.     

In vitro Toxicological Study of Metal Oxides Nanoparticles on Oxidation of Succinate in Krebs Cycle and Their Resultant Effect in Metabolic Pathways

In vitro study to evaluate toxic effects of metal oxides nanoparticles on energy producing cycle was conducted. In this study oxidation of sodium succinate in aqueous solution was investigated by using potassium ferricyanide as an oxidizing agent. Kinetic measurements were carried out on kinetic mode of spectrophotometer at λ_max 420 nm. Effect of different metal oxides (MgO and CaO) nanoparticles was observed on the oxidation of succinate at 25 ± 0.5 °C. These metal oxides nanoparticles were prepared by hydrothermal method and their characterization were done by using FTIR, TGA, SEM‐EDX, TEM and XRD. Kinetic results indicated that these nanoparticles inhibit the conversion of succinate into fumerate. The inhibition is directly dependent on particle size of the nanoparticles and it was observed that particle size is inversely related to the oxidation rate of succinate. It was concluded at the end that elevated concentrations of metal oxides nanoparticles can severely affect the Krebs cycle by inhibiting succinate oxidation and lead to various metabolic disorders.