Gold nanoparticle induces masking of amines and some therapeutic implications

Citrate capped gold nanoparticles (GNP) are effective in masking protein amines. The extent of such masking is quantified using Fourier Transform Infra Red (FTIR) spectroscopy. A strong correlation is shown to exist between a shift of amide-II peak intensity (1600-1500 cm(-1)) caused by GNP and the number of exposed amines in a given protein. The result is validated using eight different proteins. The expected out-come of such masking is inhibition of interaction between any external ligand and such amines. The prediction is validated using a simple non-enzymatic glycation of clinically important protein like crystallin.     

Improvement of conductivity of electrochemically synthesized polyaniline

The electrochemical polymerization of aqueous solution of aniline and HCl was carried out in a single compartment electrochemical cell. After 2 h of the polymerization reaction, polarity of the electrodes was reversed and kept for 1 h. By this process the conductivity of the polyaniline (PAni) formed was found to increase dramatically from 1.1 × 10^?4 to 3.0 × 10^?1 S/cm. The PAni samples obtained both by reversing the polarity (“PANI‐R”) and without reversing the polarity (“PANI”) were characterized by the infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), ultraviolet spectroscopy (UV), Hall effect experiment, X‐ray analysis (XRD) and scanning electron microscope (SEM). The results show that the increase in the conductivity of PAni through the reversion of polarity is due to the partial reduction of over oxidized sample giving more emeraldine base and hence more polaron formation with increased charge carrier density and its mobility. The degree of crystallinity and the crystallite size is decreased marginally and the d‐spacing is increased marginally due to this reduction. The PAni behaves like a p‐type semiconductor that means the majority current carriers are holes. A plausible reduction mechanism due to reversal of polarity during electrochemical polymerization is also proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Structure and properties of tailor‐made poly(ethyl acrylate)/clay nanocomposites prepared by in situ atom transfer radical polymerization

An in‐depth study was carried out on the structure and properties of a series of poly(ethyl acrylate)/clay nanocomposites prepared by in situ atom transfer radical polymerization (PNCIs) with well‐defined molecular weights and narrow molecular weight distributions. Wide‐angle X‐ray diffraction and transmission electron microscopy studies revealed an exfoliated clay morphology, whereas conventional solution blending generated an intercalated structure. The storage moduli of the PNCIs showed a moderate increase over that of the neat polymer [poly(ethyl acrylate)]. The sample containing 4 wt % clay (PNCI4, where the number following PNCI indicates the weight percentage of clay) exhibited the highest improvement (31.9% at 25°C). In PNCIs, the β‐transition temperature showed a remarkable decrease (by 175% in PNCI4) along with a shift toward higher temperatures. This indicated the probability of the anchoring of the ? OH group of the clay layers to the >C?O group of the pendant acrylate moiety, which was also confirmed by Fourier transform infrared analysis. Rheological measurements indicated a significant increase in the shear viscosity [by 9% in PNCI2, 15% in PNCI4, and 6% in the poly(ethyl acrylate)/clay nanocomposite with 2 wt % clay prepared by solution blending]. The PNCIs registered enhanced thermal stability, as indicated by the shift in the peak maximum temperature (388 and 392°C for the neat polymer and PNCI4, respectively) and a decrease in the rate of degradation (by 3.5% in PNCI2, 10.2% in PNCI4, and 49.3% in PNCI6). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Improved infrared photoluminescence characteristics from circularly ordered self-assembled Ge islands

The formation of circularly ordered Ge-islands on Si(001) has been achieved because of nonuniform strain field around the periphery of the holes patterned by focused ion beam in combination with a self-assembled growth using molecular beam epitaxy. The photoluminescence (PL) spectra obtained from patterned areas (i.e., ordered islands) show a significant signal enhancement, which sustained till 200 K, without any vertical stacking of islands. The origin of two activation energies in temperature-dependent PL spectra of the ordered islands has been explained in detail.     

Efficient Allylic Oxidation of Olefins Catalyzed by Polymer Supported Metal Schiff Base Complexes with Peroxides

Three homogeneous Cu(II), Co(II) and Ni(II) complexes of a Schiff base ligand and their heterogeneous complexes supported on poly(4-aminostyrene) were prepared and characterized by using elemental analysis, fourier transform infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, thermogravimetric analysis and scanning electron microscopy. The catalytic performance of both homogeneous and heterogeneous complexes was evaluated in the liquid phase oxidation of cyclohexene, styrene and trans-stilbene in acetonitrile with tert-butylhydroperoxide or hydrogen peroxide as the oxidant. All types of catalyst were active in oxidation; and, the complexes produce allylic oxidation products in all cases. Immobilized complexes are slightly more active than their homogeneous complexes. The polymer-supported Cu(II) complex shows a higher catalytic activity than the other metal species. The activities of the immobilized catalysts remained nearly the same after five cycles, suggesting the true heterogeneous nature of the catalyst.     

Lengthwise jute fibre properties variation and its effect on jute–polyester composite

In this study, the jute reeds were equally divided lengthwise from root to tip in three portions namely root, middle and tip. The fibre diameter, fineness, tensile strength and bundle strength of the three portion jute were evaluated and compared. Unidirectional composites containing about 35(wt/wt)% jute fibre by weight were produced in unsaturated polyester resin matrix. The effect of fibre property variation in composite’s mechanical properties was studied. Tensile and flexural properties of composites made from three portions of jute reed were studied. It was observed that tensile and flexural strength of root portion based composites are 44% and 35% higher than tip portion based composites. Tensile and flexural modulus of tip portion based composites is 18% and 17% higher than root portion based composites.     

Thermoplastic elastomer blend based on EMA and NBR; optimization of process parameters

EMA–NBR has been explored to be a potential thermoplastic elastomer blend having good thermal stability as well as oil resistance property. The present investigation reports the optimization of process parameters for the novel polymer blends based on poly(ethylene-co-methyl acrylate) (EMA) and poly(acrylonitrile-co-butadiene) rubber (NBR) with criteria based on the statistical design of experiment (Taguchi L9 orthogonal array). In this case, the polymer blends were prepared by changing the polymer blending conditions such as mixing temperature, mixing time and rotor speed as per Taguchi's L9 orthogonal array. Optimization of the process parameters was carried out based on the physicomechanical properties such as tensile strength, elongation at break, hardness, and tensile impact strength of the resulting EMA/NBR blend. Each processing parameter has been optimized from the experimental data, which are converted into signal-to-noise ratio. The standard statistical technique of analysis of variance result was used to evaluate the proportional role of the different control variables. It has been found that the mixing temperature play very significant role trailed by rotor speed and mixing time in controlling droplet matrix morphology of the EMA/NBR blends. Predominantly, these factors affect the size of the NBR domain and its distribution in the EMA matrix, which in turn have a notable contribution to the physicomechanical properties of the blends. By the optimization of processing conditions, the NBR matrix domain size greatly decreases, leading to significant improvement in physicomechanical properties of the EMA/NBR blends. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48900.     

Selective Oxidation of Organic Substrates in Presence of H2O2 using a Polymer-Anchored Iron(III)-Ferrocene Complex

An eco-friendly, cheap and reusable polymer-anchored iron(III)-ferrocene Schiff base catalyst has been designed for the efficient oxidation of alkanes and alcohols. Oxidation reactions were done by using a greener oxidant 30 % aqueous hydrogen peroxide in acetonitrile medium at room temperature for alcohols and at 60 °C for alkanes. Both the alkanes and alcohols have been selectively oxidized to their corresponding aldehydes and ketones in excellent yields. This catalyst has shown excellent catalytic activity with high selectivity and recyclability. It is found that this catalyst can be reused up to six cycles without loss of its original activities.     

A highly efficient polymer‐anchored palladium(II) complex catalyst for hydrogenation,Heck cross‐coupling and cyanation reactions

BACKGROUND: Precise architectures of steric and electronic properties of palladium species play a crucial role in designing highly functionalized catalyst systems responsible for target organic transformations. Pd catalysts supported on polymer materials have been employed extensively as catalysts not only for hydrogenation but also for coupling reactions in the production of fine chemicals. RESULTS: A new polymer‐anchored Pd(II) complex has been synthesized and characterized. The catalyst shows high catalytic activity in the hydrogenation of styrene oxide, Heck cross‐coupling and cyanation reactions of aryl halides. The effect of various reaction parameters were investigated to optimize reaction conditions. The catalytic system shows good activity in the hydrogenation of styrene oxide (conversion 98%) with a selectivity to 2‐phenylethanol (93%) which is higher than its homogeneous analogues. The catalyst also exhibits excellent catalytic activity for the Heck cross‐coupling and cyanation reactions of various substituted and non‐substituted aryl halides. CONCLUSIONS: Results demonstrate that the catalyst is robust and stable and can be recovered quantitatively by simple filtration and reused several times without loss of activity. Copyright © 2010 Society of Chemical Industry