Sonochemical assisted synthesis and spectroscopic characterization of Fe3+ doped ZnO diluted magnetic semiconductor

Fe³⁺ doped ZnO nanopowder has been synthesized by sonochemical assistance and characterized by different spectroscopic techniques. The structure, surface morphologies and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectrometer (PL) and ultraviolet–visible spectrophotometer. XRD reveals that Fe³⁺ ions enter into ZnO lattices without any secondary phases. SEM micrographs of prepared sample show that surface is rough and stone like structure with different sizes. PL studies of Fe³⁺ doped ZnO nanopowder exhibits ultraviolet and blue emission bands. Magnetometric measurements (vibrating sample magnetometer) indicate ferromagnetic behavior at room temperature. This observation is further confirmed by the EPR spectrum of Fe³⁺ doped ZnO at room temperature.     

Detection of irradiated lamb meat with bone: effect of chilled storage and cooking on esr signal strength

Summary The effect of gamma-irradiation doses of 1, 2, 4 and 5 kGy on ESR signal intensity in pre-packed irradiated lamb meat chunks containing bones was studied. Irradiation-induced a characteristic ESR signal in bone that was not detected in non-irradiated samples and its intensity was proportional to irradiation dose up to 5 kGy. In samples irradiated to 2.5 kGy for shelf-life enhancement, ESR signal intensity was monitored immediately after irradiation and subsequently at weekly intervals during storage at 0–3 °C and after cooking by different methods. Hind leg bones (femur) displayed a higher signal intensity than rib bones. The ESR signal intensity faded by 30 and 42% during 4 weeks at 0–3 °C in hind leg and rib bones, respectively. The magnitude of ESR signal in hind leg bone declined by a maximum of 30% upon pressure cooking (for 15 min), 10% on microwave cooking (for 5 min) and 13% after boiling (for 30 min). However, in the case of rib bones, all cooking methods reduced the ESR signal by about 40%. Storage of irradiated freeze-dried bone powder samples at ambient temperature also resulted in slight reduction in ESR signal intensity. Results point to the suitability of ESR technique for detection of irradiated lamb meat even after storage or cooking, and also in samples that had been stored and then cooked.     

Novel high performance fibres

The need for high performance materials for aerospace and other structural engineering applications has led to the development of carbon fibres. At IIT Delhi, an attempt is being made to develop acrylic precursor fibres for manufacturing carbon fibres indigenously. The present study deals with the structural regulation of acrylic precursors during thermo-oxidative stabilization and subsequent carbonization. A new microporous acrylic fibre-acrysorb has also been developed which has high water imbibition and moisture sorption properties. Production of X-ray opaque and antistatic polyester fibres has also been high-lighted.     

Two-photon-assisted excited state absorption in nanocomposite films of PbS stabilized in a synthetic glue matrix

Strong nonlinear absorption is observed in nanocomposite films containing PbS nanocrystals of mean size of 3.3?nm stabilized in a commercial poly(vinyl acetate) glue by a novel and simple chemical route of synthesis. A significant blueshift of the optical absorption edge indicates strong quantum confinement. The mean nanocrystal size was characterized by x-ray diffraction and transmission electron microscopy. The surface structure of nanocrystals is analysed using infrared spectroscopy. The excitonic transitions are probed by photoacoustic spectroscopy and the results are analysed on the basis of theoretical calculations using envelope function formalism. Results of open aperture z-scan experiments suggest a model involving saturable absorption followed by two-photon absorption at a lower concentration while the data for a higher concentration fitted saturable absorption followed by three-photon absorption. Free carrier absorption due to two-photon-assisted excited state absorption appears to be the predominant mechanism of optical nonlinearity.     

In vitro Antifungal Activity of Dehydrozingerone and its Fungitoxic Properties

Abstract: The efficacy of Dehydrozingerone (DZ; dehydroderivative of zingerone) as an antifungal agent and its mode of action against food spoilage fungal pathogens was studied and presented. DZ is a constituent of ginger (Zingiber officinale rhizomes) and structural half analogue of curcumin. Its efficacy against Aspergillus oryzae, Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus, Fusarium oxysporum and Penicillium chrysogenum was evaluated. Effect of DZ on the growth and sporulation of A. ochraceus was also studied. The fungal species were susceptible to DZ and the minimum inhibitory concentration and fungicidal concentration ranged from 755 to 911 μM and 880 to 1041 μM respectively. The mycelial and spore germination was significantly inhibited; reduction in the weight of the cell mass, carbohydrate, protein, DNA and RNA constituents in the cells isolated from cultures of A. ochraceus grown with DZ were observed. Scanning electron microscopy studies revealed morphological observations such as cell lysis, inhibition and morphological alterations in hyphae and sporulation in A. ochraceus on treatment with DZ. Practical application: Current investigations revealed that DZ is a potential antifungal agent and can find application as an additive or adjuvant in food and pharmaceutical industries after appropriate toxicological studies.     

Retrofitment of a CNC machine for hybrid layered manufacturing

Subtractive manufacturing [computer numerical controlled (CNC) machining] has high quality geometric and material properties but is slow, costly, and infeasible in some cases. On the contrary additive manufacturing (rapid prototyping) has total automation but compromises quality. A hybrid layered manufacturing process presented in this study combines the best features of both these approaches. It uses arc weld deposition for building near-net shapes, which are subsequently finish machined. Time and cost savings of this process can be attributed to reduction in NC programming effort and elimination of rough machining. It is envisioned as a low cost retrofitment to any existing CNC machine for making metallic objects without disturbing its original functionalities. Near-net shape building and finish machining happening at the same station is the unique feature of this process. A customized software generates the NC program for near-net shape building. The intricate details of integrating arc welding unit with a CNC milling machine are presented in this paper.     

Effect of reaction medium on radical copolymerization of acrylonitrile with vinyl acids

Radical polymerization of acrylonitrile (AN) with methacrylic acid (MAA) and itaconic acid (IA) was carried out in a mixture of dimethylformamide (DMF) and water at 70°C using α, α′‐azobisisobutyronitrile (AIBN) as an initiator. Monomer feed in the polymerization vessel was 98:2 (AN:MAA/IA) in the molar ratio, and the DMF:H₂O ratio was varied between 20:80 and 80:20 (w/w). Copolymers were characterized by FTIR, carbon, hydrogen, nitrogen elemental CHN analysis, ¹H‐ and ¹³C‐NMR, and viscometry. The rate of polymerization (R_p) was found to decrease with an increase in DMF concentration in the reaction medium, that is, in 20% DMF for AN–MAA system, the R_p is 1.23% min⁻¹ in 1 h of polymerization, while in 80% DMF, R_p is reduced to 0.37% min⁻¹. The nature of the vinyl acid also affects the R_p. It has been shown that the rate of polymerization is higher for an AN–MAA system as compared to an AN–IA system (R_p = 1.0% min⁻¹) and the methacrylic or itaconic acid content in the copolymer increases with an increase in the DMF concentration. The MAA content in the poly(AN–MAA) polymer produced in 20% DMF is 3.2 mol %, which increases to 6.1 mol % (calculated through FTIR spectra) when DMF is increased to 80% in the reaction medium. The intrinsic viscosity [η] of the poly(AN–IA) and poly(AN–MAA) copolymers in DMF was found to be in the range of 0.67–2.90 dLg⁻¹ depending on the reaction medium. In determining the intrinsic viscosity, a definite deviation from rectilinearity of the concentration dependence in the high‐dilution region is observed, thereby demonstrating the polyelectrolyte behavior of these polymers. Through FTIR and NMR spectral studies, PAN homopolymer and other copolymers have shown the formation of a small quantity of acrylamide units. In addition copolymer P₁₀, which contains 10.1 mol % IA, has shown anhydride formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1640–1652, 2001     

Detection of Lathyrus sativus in processed chickpea‐ and red gram‐based products by thin layer chromatography

Excessive consumption of Lathyrus sativus leads to crippling, irreversible paralysis of both lower limbs, mainly in males. This is attributed to the presence of a non‐protein amino acid, β‐N‐oxalyl‐L ‐2,3‐diaminopropionic acid or β‐N‐oxalylamino‐L ‐alanine. Using a thin layer chromatography method developed in our laboratory, adulteration of chickpea and red gram with L sativus in pressure‐cooked batters could be detected at levels of 100 and 200 g kg^?1 respectively. When processed as a curried liquid dal, L sativus could be detected at 200 g kg^?1 in chickpea and 100 g kg^?1 in red gram. Processing into fried bhajiyas resulted in a detection limit of 200 g kg^?1 in both red gram and chickpea. © 2003 Society of Chemical Industry     

An approach to the detection of synthetic milk in dairy milk: 4. Effect of the addition of synthetic milk on the flow behaviour of pure cow milk

The flow behaviour of cow milk, synthetic milk and their blends was evaluated with a Haake rheometer. Changes in flow behaviour are thought to be due to detergent, an important constituent of synthetic milk, which emulsifies the vegetable fat in the aqueous phase. The results are of value in detecting very low levels (1–10%) of synthetic milk in cow milk.