Effect of Growth Temperature on Bamboo-shaped Carbon–Nitrogen (C–N) Nanotubes Synthesized Using Ferrocene Acetonitrile Precursor

This investigation deals with the effect of growth temperature on the microstructure, nitrogen content, and crystallinity of C–N nanotubes. The X-ray photoelectron spectroscopic (XPS) study reveals that the atomic percentage of nitrogen content in nanotubes decreases with an increase in growth temperature. Transmission electron microscopic investigations indicate that the bamboo compartment distance increases with an increase in growth temperature. The diameter of the nanotubes also increases with increasing growth temperature. Raman modes sharpen while the normalized intensity of the defect mode decreases almost linearly with increasing growth temperature. These changes are attributed to the reduction of defect concentration due to an increase in crystal planar domain sizes in graphite sheets with increasing temperature. Both XPS and Raman spectral observations indicate that the C–N nanotubes grown at lower temperatures possess higher degree of disorder and higher N incorporation.     

Aesthetical design of a car profile: a Kano model-based hybrid approach

An amicable aesthetical design of a product is prudent for its wide acceptability and viability. Selection of shape parameters with customer satisfaction is critical in aesthetical design and a challenging task for designers. In the present work, the authors proposed a sequential approach to design a car profile with aesthetical aspects. The methodology is based on Kano model that provides a framework for incorporation of customer satisfaction with the design requirements. Further, Taguchi's robust design approach has been used to find the optimum level of the parameter to achieve initial design estimates and thereafter, response surface method (RSM) is applied to refine the optimum values, precisely. The methodology has been illustrated with a case study.     

A kinetic model for the enzyme-catalyzed self-epoxidation of oleic acid

This paper reports a kinetic model for the selfepoxidation of oleic acid with toluene as solvent and Novozym 435 (a commercially available preparation of immobilized Candida antarctica lipase) as catalyst at 30°C. The effects of various parameters on the conversion and rates of reaction were studied. Both the initial rate and the progress curve data were used to fit an ordered bi-bi model. At low temperatures, the rate of epoxidation was faster than the rate of deactivation of the enzyme by hydrogen peroxide.     

Attenuation of ultrasonic waves in V, Nb and Ta at low temperatures

Variation of ultrasonic attenuation and velocities with temperature have been evaluated in the temperature range 5-50 K due to electron-phonon interaction mechanism in transition metals vanadium, niobium and tantalum for longitudinal and shear waves. For this evaluation, we have also computed the second order elastic constants using Morse potential. Behaviour of acoustical phonons in these bcc metals is different from other normal metals, intermetallics, semimetallics and alloys. Some characteristic features of these materials connected to ultrasonic parameters are discussed.     

Amperometric determination of tyramine in sauce and beer by epoxy resin biocomposite membrane bound tyramine oxidase

A method is described for construction of an amperometric biosensor for specific determination of tyramine, using black gram tyramine oxidase immobilized covalently on an epoxy resin membrane. The biosensor had optimum response within 10 s at pH 8.5 and 35 °C. A linear relationship was observed between tyramine concentrations and current (mA) in the range of 0.24 to 3.47 mg/dL. The biosensor was employed for determination of tyramine in beer and sauce. The detection limit of sensor was 0.24 mg/dL. The mean analytical recovery of added tyramine (0.5 and 1.0 mg/dL) was 97.3 ± 2.3 and 95.9 ± 3.4%. Within and between batch coefficient of variation were 5.1 and 5.34%, respectively. Enzyme electrode showed 35% loss in its initial activity after its regular use over a period of 2 months. The biosensor has the advantage that it does not suffer from leaching of enzyme and measures tyramine specifically.     

Isatin compounds as corrosion inhibitors for N80 steel in 15% HCl

The inhibition effect of two synthesized isatin compounds namely 1-morpholinomethyl-3-(1-N-dithiooxamide)iminoisatin [MMTOI] and 1-diphenylaminomethyl-3-(1-N-dithiooxamide)iminoisatin [PAMTOI] on the corrosion inhibition of N80 steel in 15% HCl solution was studied by polarization, EIS and weight loss measurements. It was found that both the inhibitors were effective and their inhibition efficiency was significantly increased with increasing concentration. Polarization curves revealed that the used inhibitors represent mixed-type inhibitors. Adsorption of these inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance, and was found also to obey Langmuir isotherm.     

Enhanced antibacterial activity of tetramethylguanidinium-conjugated linear polyethylenimine polymers

In the present study, varying amounts of tetramethylguanidinium moiety have been conjugated to linear polyethylenimine to obtain linear polyethylenimine-tmg (LPTG) polymers. Incorporation of hydrophobic and highly basic moiety in the polymeric backbone resulted in the significant improvement in the antibacterial activity which was confirmed by zone of inhibition and MIC assays. Further, the results of transmission electron microscopy and confocal studies revealed that the projected LPTG polymers possessed higher antibacterial activity than the native polymer. In addition, these modified polyethylenimine (PEI) polymers were capable of reducing auric chloride into stable gold nanoparticles. These polyamine-stabilized gold nanoparticles can be used in various biomedical applications.     

Study of crystal structure,dielectric, magnetic and magnetoelecrtic properties of xCoFe2O4-(1-x)Na0.5Bi0.5TiO3 composites

Multiferroic composites of spinel ferrite and ferroelectric xCoFe₂O₄ – (1-x)Na_0.5Bi_0.5TiO₃ (with x = 0.10,0.30,0.50) were efficiently prepared by standard solid state reaction mechanism. X-ray diffractometer was used to analyze crystal structure of the prepared composites. The observed XRD patterns of the composites comprise peaks of both the phases i.e. ferrite and ferroelectric, with no sign of secondary peaks. Rietveld refinement of XRD data further confirms the coexistence of these two phases with cubic (Fd3m) and rhombohedral (R3c) symmetry corresponding to ferrite and ferroelectric phase respectively. The 3-dimensional overview of crystal structure of pure CoFe₂O₄ and Na_0.5Bi_0.5TiO₃ and of composite 0.50CoFe₂O₄?0.50Na_0.5Bi_0.5TiO₃ is generated by using refined parameters. The dielectric constant (ε´) and dielectric loss (tanδ) values were recorded as a function of frequency ranging from 100?Hz to 7?MHz and at different temperatures. Both ε´ and tanδ follow dispersion pattern at lower frequencies while show frequency independent behavior at higher frequencies. The magnetic evaluation carried by analyzing M-H hysteresis loop reveals the ferrimagnetic characteristics of these composites. The highest value of magnetic moment is 1.12μ_B observed for composite 0.50CoFe₂O₄ – 0.50Na_0.5Bi_0.5TiO_3. Magnetoelectric (ME) voltage coefficient (α) was also demonstrated to observe the interaction between ferrite and ferroelectric phases. The highest value of α (72.72μV/Oe cm) is obtained for low ferrite composition 0.10CoFe₂O₄ – 0.90Na_0.5Bi_0.5TiO₃, which suggests the dependence of magnetoelectric response on the resistivity of the composites.     

NAFLA – Ein Simulationswerkzeug zur analytischen Abschätzung von Schadstofffahnenlängen

Groundwater pollution with organic contaminants remains a world-wide problem. Before selection of any remediation technique, it is important to pre-assess contaminated sites with respect to their hazard. For this, several analytical and numerical approaches have been used and an initial assessment of contaminated sites the MS-Excel^© tool “NAFLA” was developed. “NAFLA” allows a quick and straightforward calculation and comparison of some analytical approaches for the estimation of maximum plume length under steady-state conditions. These approaches differ from each other in source geometry, model domain orientation, and in the consideration of (bio)chemical reaction within the domain. In this communication, we provide details about the development of “NAFLA”, its possible usage and information for users. The tool is especially designed for application in student education, by authorities and consultants.     

Synthesis and characterization of Cu nanotubes and nanothreads by electrical arc evaporation

We report the formation and characterization of copper nanostructures, nanotubules and nanothreads, which were obtained by electrical arc evaporation of Cu electrodes under varied conditions of He ambience. Electrical arc evaporation was done with approximately 10 V and (approximately 50-100 A) DC current. The current was used in a pulse mode. The evaporated material was condensed on a formvar-coated Cu grid mounted on a liquid N2-cooled specimen holder. Transmission electron microscopy was employed to characterize the condensed materials. These investigations revealed that the condensed materials consisted of the mentioned nanostructures. Nanotubes and nanothreads are formed for a He pressure in the chamber corresponding to approximately 140 and approximately 500 torr, respectively. Extensive electron microscopic investigations showed that the diameter of the nanotubes varied from approximately 5 nm to approximately 50 nm and their length from 2 microns to 3 microns.