Synthesis and physicochemical characterization of poly(azomethine)esters containing aliphatic/aromatic moieties: Electrical studies complemented by DFT calculation

A conducting poly(azomethine)ester was prepared by solution phase polycondensation of a preformed Schiff base, 4‐((4‐(4‐(4‐hydroxybenzlideneamino) phenoxy)phenylimino)methyl)phenol and isophthaloyl chloride (I). Different aliphatic/aromatic moieties were incorporated for examining their effect on the electronic properties of material. The resulting polymers (10^?4 to 25 S cm^?1) were doped with silver (10^?6 to 10^?2 S cm^?1) and blended with polyaniline (10^?1 to 13.4 S cm^?1) to enhance their electrical conductivity. Polymer/polyaniline blends had superior conductivity even at low polyaniline concentration relative to the silver‐doped chains. The data obtained experimentally were complemented by density function theory at the 6–31G/B3LYP level. The results showed that ΔE along with lowest unoccupied molecular orbital and highest occupied molecular orbital electron density accounts for the electrical properties. Spectroscopic (¹HNMR, FTIR) and elemental analysis were used for structural elucidation. Structure–property relation in term of WXRD, SEM‐EDX, atomic force microscope, LLS, and thermal behavior was studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40698.     

Methyl formation from methanol decomposition on Pd{111} and Pt{111}

The decomposition of CH₃OH adsorbed on Pd{111} and Pt{111} is compared as the surface is heated between 100 and 500 K. Using secondary ion mass spectrometry (SIMS) and thermal programmed desorption (TPD) it is suggested that an anomalous CH ₃ ⁺ ion signal observed previously by Akhter and White on oxygen precovered Pt{111} arises from the formation of a surface CH₃ species resulting from activation of the C-O bond of CH₃OH. This interpretation stems from a recent observation by Levis, Zhicheng and Winograd that CH₃OH decomposes to CH₃, OH and OCH₃ on clean Pd{111} between 100 and 300 K. The results are discussed in terms of the relative ability of these metals to synthesize CH₃OH from CO and H₂.     

Control of myocardial contractile function by the level of beta-adrenergic receptor kinase 1 in gene-targeted mice

We studied the effect of alterations in the level of myocardial beta-adrenergic receptor kinase betaARK1) in two types of genetically altered mice. The first group is heterozygous for betaARK1 gene ablation, betaARK1(+/-), and the second is not only heterozygous for betaARK1 gene ablation but is also transgenic for cardiac-specific overexpression of a betaARK1 COOH-terminal inhibitor peptide, betaARK1(+/-)betaARKct. In contrast to the embryonic lethal phenotype of the homozygous betaARK1 knockout (Jaber, M., Koch, W. J., Rockman, H. A., Smith, B., Bond, R. A., Sulik, K., Ross, J., Jr., Lefkowitz, R. J., Caron, M. G., and Giros, B. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 12974-12979), betaARK1(+/-) mice develop normally. Cardiac catheterization was performed in mice and showed a stepwise increase in contractile function in the betaARK1(+/-) and betaARK1(+/-)betaARKct mice with the greatest level observed in the betaARK1(+/-)betaARKct animals. Contractile parameters were measured in adult myocytes isolated from both groups of gene-targeted animals. A significantly greater increase in percent cell shortening and rate of cell shortening following isoproterenol stimulation was observed in the betaARK1(+/-) and betaARK1(+/-)betaARKct myocytes compared with wild-type cells, indicating a progressive increase in intrinsic contractility. These data demonstrate that contractile function can be modulated by the level of betaARK1 activity. This has important implications in disease states such as heart failure (in which betaARK1 activity is increased) and suggests that betaARK1 should be considered as a therapeutic target in this situation. Even partial inhibition of betaARK1 activity enhances beta-adrenergic receptor signaling leading to improved functional catecholamine responsiveness.     

Effect of flavonoids on the oxidative stability of corn oil during deep frying

To study the effect of flavonoids on the stability of frying oil, refined corn oil was analysed periodically for its peroxide value (PV), p‐anisidine value (p‐AV) and iodine value (IV) after its use for deep‐frying of French fries at 180 °C for varying periods of time, namely 30, 60 and 90 min. PV and p‐AV values increased with respect to time while a decrease in IV was observed with increase in time (P < 0.001). Deep‐frying of French fries in corn oil was then carried out in the presence of flavonoids, viz. pelargonidin, cyanidin, quercetin, myrecetin and gallic acid as antioxidants. All antioxidants effectively reduced the oxidation rate in the oil, as detected by decrease in PVs and p‐AVs and relatively low reduction rate in IVs (P < 0.001). The order of antioxidative activity was gallic acid > quercetin > myrecetin > cyanidin > pelargonidin.     

Karanja (Pongamia Pinnata) biodiesel production in Bangladesh, characterization of karanja biodiesel and its effect on diesel emissions

This paper presents production of biodiesel (BD) from non-edible renewable karanja (Pongamia Pinnata) oil, determination of BD properties and influence of BD on engine performance and emissions. Bangladesh imports 2.4 million metric ton (MT) DF each year [M.N. Nabi, M.S. Akhter, K.M.F. Islam, Prospect of biodiesel production from jatropha curcas, a promising non edible oil seed in Bangladesh, International Conference on Mechanical Engineering (ICME, Dhaka, Bangladesh) Proceedings 2007, paper no. ICME07-TH-06. [1]]. It has 0.32 million hectare of unused land [M.N. Nabi, S.M.N. Hoque, M.S. Uddin, Prospect of Jatropha curcas and pithraj cultivation in Bangladesh, Journal of Engineering and Technology, IUT, Dhaka, Bangladesh, 7 (1) (2009) 41–54. [2]]. It has been found that cultivating of karanja plant in such unused land; Bangladesh can reduce DF import by 28%. Karanja methyl ester (KME), which is termed as BD, has been produced by well-known transesterification process. The properties of B100 (B100) and its blends were determined mainly according to ASTM standard and some of them were as per EN14214 standard. The Fourier transform infrared (FTIR) analysis showed that the DF fuel contained mainly alkanes and alkens, while the B100 contained mainly esters. The gas chromatography (GC) of B100 revealed that a maximum of 97% methyl ester was produced from karanja oil. Engine experiment result showed that all BD blends reduced engine emissions including carbon monoxide (CO), smoke and engine noise, but increased oxides of nitrogen (NOx). Compared to DF, B100 reduced CO, and smoke emissions by 50 and 43%, while a 15% increase in NOx emission was observed with the B100. Compared to DF, engine noise with B100 was reduced by 2.5 dB.     

A TCAD approach for non-linear evaluation of microwave power transistor and its experimental verification by LDMOS

A simulation technique is developed in TCAD to study the non-linear behavior of RF power transistor. The technique is based on semiconductor transport equations to swot up the overall non-linearity’s occurring in RF power transistor. Computational load-pull simulation technique (CLP) developed in our group, is further extended to study the non-linear effects inside the transistor structure by conventional two-tone RF signals, and initial simulations were done in time domain. The technique is helpful to detect, understand the phenomena and its mechanism which can be resolved and improve the transistor performance. By this technique, the third order intermodulation distortion (IMD₃) was observed at different power levels. The technique was successfully implemented on a laterally-diffused field effect transistor (LDMOS). The value of IMD₃ obtained is −22 dBc at 1-dB compression point (P _{1 dB}) while at 10 dB back off the value increases to −36 dBc. Simulation results were experimentally verified by fabricating a power amplifier with the similar LDMOS transistor.     

Treatment of Arsenic-Contaminated Soils. ?I: Soil Characterization

Industrial sites frequently have arsenic-contaminated soils as a result of repeated applications of arsenic herbicides. Four such sites were investigated to determine the suitability of cement-based solidification∕stabilization (S∕S) for in situ soil treatment. Arsenic concentrations ranged up to about 2,000 ppm in the soil, although leachability was relatively low. No toxicity characteristic leaching procedure leachates showed As concentrations as high as 5 mg∕L. The low leachability appears to be due, at least in part, to iron present in the soil. Although soils with higher As concentrations generally showed greater leachability, a somewhat stronger relationship existed between the percentage of As in the soil that was leached and the iron concentration in the soil. Another factor working in favor of the success of S∕S in the present cases is the sandy character of the soils with little clay or organic content. Thus, the quartz sand will serve as an aggregate and should not offer any interferences to cement hydration. A third favorable circumstance is afforded by the oxidizing character of the soils. The weathered arsenic present in the soils should be in the form of As(V), and arsenate salts present a wider range of possibilities for precipitation of insoluble arsenic species than arsenite salts. A significant variable with the potential to affect S∕S is the soil moisture content, which varied greatly among the four sites due to differing water table depth.     

Antimicrobial activity of the polyphenolic fractions derived from Grewia asiatica,Eugenia jambolana and Carissa carandas

Crude methanolic extracts from Grewia asiatica, Eugenia jambolana and Carissa carandas were separated into four major fractions viz. phenolic acids, flavanols, flavonols and anthocyanins which were then analysed for their total phenolic, flavonoid contents, and antimicrobial effects. In addition, anthocyanin fraction was also analysed for total anthocyanins, total colour and polymeric pigments. Total phenolics and flavonoids were highest in the fractions from E. jambolana and lowest in C. carandas, the order being phenolic acid > flavanols > flavonols > anthocyanins in all fruits. All fractions showed significant antibacterial activity except anthocyanin. Being the most active, phenolic acid fractions were also tested for their antifungal activity, the fractions of C. carandas and G. asiatica substantially inhibited all the tested fungal species. These results are being reported for the first time.     

Synthesis and characterization of some novel thermally stable poly(amide–imide)s

Two new diamines with built-in amide linkage were synthesized from p-nitrobenzoyl chloride in two steps and characterized by their melting points, elemental analyses, FT-IR and ¹H–NMR spectral studies. One of the diamine precursors was also characterized by single crystal X-ray analysis indicating the trans orientation of amide bonds. The planes of the aromatic rings formed dihedral angles in the range of 11.7°–56.2° and the crystal packing was stabilized by N–H···O hydrogen bonds. The synthesized diamines were then polymerized with three commercially available dianhydrides either by one-step solution technique or by two-step procedure involving ring-opening poly-addition to give polyamic acid followed by cyclic dehydration. The resulting poly(amide–imide)s were characterized by their elemental analyses and FTIR spectroscopy. The polymers possessed excellent chemical resistance and were found insoluble in almost all the common solvents tested except conc. H₂SO₄, in which these showed inherent viscosities in the range 0.47–0.73 dL g⁻¹ at 28 °C. The thermal behavior of the polymers, investigated by the DSC and TG analyses, revealed that the products were stable up to 300 °C in nitrogen. The activation energies of pyrolysis, entropy, and enthalpy values for each of the synthesized polymers were also estimated by Horowitz and Metzger method using thermal degradation data. These values were high exhibiting the remarkable thermal stability of the poly(amide–imide)s. Wide-angle X-ray studies of the polymers were also carried out which provided information about their morphology.