Formal synthesis of (+)-didemniserinolipid B

The formal synthesis of (+)-didemniserinolipid B is achieved using Weinreb reaction, Yadav’s chiral propargyl alcohol protocol and hydrolytic ketal formation as the key steps.     

Effect of Various Growth Hormone Concentration and Combination on Callus Induction,Nature of Callus and Callogenic Response of Nerium odorum

Nerium odorum, Linn. (Apocynaceae) is an important evergreen shrub. It is heat, salinity and drought tolerant. Plants with milky sap have medicinal value, mainly cardenolides, flavonoids and terpenes. It is used for wastewater purification and for restoration of riparian woodlands. In view of these facts, the study was conducted for micropropagation of N. odorum. Murashige and Skoog (MS) media supplemented with different concentrations (0.5–10.0 mg/l) of 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BAP) and kinetin (Kin) were used singly and in combinations. Among all the growth hormones, 2,4-D was the best for callus induction (75 % in stem and 79 % in leaf) and in combination 2,4-D and BAP (78 % in stem and 81 % in leaf). The day of callus induction started from the 19th to the 37th day. This variation is due to the differences in culture conditions and the age of explants. The fresh and dry weight and moisture content showed good growth of callus, which is used in further studies of alkaloid production. Micropropagation of this plant allows the production of clones at a fast rate and in continuous manner. This work can lead to the development of an efficient protocol for callus induction and other issues.     

Heterocyclic steroids: Synthesis of androsteno[17,16-d]pyrazoles and androsteno[17,16-e]pyrimidines

The Vilsmeier-Haack reaction of 3β-acetoxyandost-5-en-17-one ( 1 ) with phosporous oxychloride and dimethylformamide gave 3β-acetoxy-17-chloro-16-formylandrosta-5,16-diene ( 2 ). Reaction of 2 with hydrazine and phenylhydrazine provided substituted 5-androsteno[17,16-d]pyrazoles 3 and 4 respectively. Similarly, condensation of 2 with urea and guanidine hydrochloride revealed the formation of the corresponding substituted pyrimidines 5 and 6 respectively.     

Taguchi method optimization of wax production from pyrolysis of waste polypropylene

Present research deals with the conversion of waste commodity plastics to valuable commercial product in the form of wax by pyrolysis. Optimization of both processes yield and produced wax quality was performed by means of a statistical tool originally proposed by G. Taguchi, using temperature, catalyst, carrier gas, and dwell time as the parameters. The obtained wax was characterized by Raman spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Yield of wax was found to be maximum when the parameters were 600 °C, Fe catalyst, nitrogen gas atmosphere, and 15 min time. However, stability of the wax was found to be optimum at 700 °C. Calorific value of the wax thus obtained was ~43 MJ kg^?1, which supports its suitability as fuels like other petroleum products.     

Effects of high-temperature annealing on magnetic ordering in thin films of Bi2O3-CaO-Fe2O3

Magnetic properties of rf sputtered (0.5–x) Bi₂O₃-x CaO-0.5 Fe₂O₃ (x=0–0.5) have been studied through magnetization and ferromagnetic resonance (FMR) measurements. Films prepared in a mixed oxygen-argon atmosphere are amorphous and paramagnetic. Samples annealed in air at temperatures of 700–1000 K show a ferrimagnetic behavior even though X-ray diffraction data for the films do not indicate the precipitation of any crystalline ferrimagnetic compounds. The room-temperature saturation magnetization 4M and the uniaxial anisotropy field H _u , decrease with increasing x. The Curie temperature and the gyromagnetic ratio increase with increase in the concentration of CaO. Studies on the effects of sputtering atmospheres on magnetic parameters show that films sputtered in oxygen-rich atmospheres have a large 4M and H _u , and a relatively small and FMR line-width. Ordered amorphous clusters are suggested to give rise to the observed ferrimagnetic character in the annealed films.     

Effect of platinum on the photoelectrochemical behavior of lead oxide thin film

The effect of Pt on the photoelectrochemical behavior of lead oxide prepared from anodization of Pb-Pt alloy containing various concentrations of Pt has been studied. It is observed that, while Pt reduces the resistivity of the oxide film, it also reduces the photoconversion efficiency of the photoelectrochemical cell prepared from this material. The reason for this low efficiency is discussed. Received: 19 November 1997 / Accepted: 9 March 1998     

Photodegradation of polyaromatic hydrocarbons over thin film of TiO2 nanoparticles; a study of intermediate photoproducts

The photocatalytic degradation of saturated aqueous solution of naphthalene and anthracene was studied over thin films of porous TiO₂ particles on glass substrate, prepared by sol–gel process. Surface morphology and structural features were studied by SEM, TEM and Laser Raman Spectroscopy. These films have been found to be very efficient and the total photomineralisation of these organics to carbon dioxide and water occurs in air-equilibrated solution within 1 h. Concentration changes linearly with the illumination time, and high rate constants are obtained for the degradation of these organics. The pH of the solution changes with the irradiation time due to the formation of intermediate photoproducts, e.g., 5,8-dihydroxynaphthaquinone, and 9,10-anthraquinone, etc. Photodegradation mechanism and the detection of reaction intermediates have been discussed in details.     

Opto-electrical properties of amorphous carbon thin film deposited from natural precursor camphor

A simple thermal chemical vapor deposition technique is employed for the pyrolysis of a natural precursor “camphor” and deposition of carbon films on alumina substrate at higher temperatures (600-900 °C). X-ray diffraction measurement reveals the amorphous structure of these films. The carbon films properties are found to significantly vary with the deposition temperatures. At higher deposition temperature, films have shown predominately sp²-bonded carbon and therefore, higher conductivity and lower optical band gap (Tauc gap). These amorphous carbon (a-C) films are also characterized with Raman and X-ray photoelectron spectroscopy. In addition, electrical and optical properties are measured. The thermoelectric measurement shows these as-grown a-C films are p-type in nature.