Synthesis,structural and optical properties of Er doped,Li doped and Er + Li co-doped ZnO nanocrystallites by solution-combustion method

Pure zinc oxide (ZnO) and 2 mol% of Er, 1 mol% of Li individually doped and Er + Li co-doped ZnO nanopowders were synthesized by auto-combustion method. Crystal structure and grain size were characterized by X-ray diffractometer and found that all synthesized samples have hexagonal wurtzite crystal structure. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) studies were used to determine the morphology and size of the nanocrystallites. A UV–VIS measurement shows four absorbance peaks in the visible regions and the band gap is slowly blue shifted after annealing at 800 °C. The presence of Er, Li and the hexagonal wurtzite structure was confirmed by FT-IR studies. FT-Raman spectroscopy has been employed to study the crystalline quality and structural disorders.     

Development of non-enzymatic ZnO nanocomposite-based optical sensor for l-lactate detection in tomato samples

l -lactate is a conjugate base of α-hydroxy acid, a key organic chemical in food processing, fermentation, biology and chemical industries. We are reporting for the first time a facile and rapid non-enzymatic nanosensor for l -lactate detection in tomato-based products using 3-aminophenylboronic acid (3-APBA)-added zinc oxide nanoparticles (ZnO NPs). 3-APBA-functionalised ZnO NPs have a selective and stable SPR intensity change at pH 5.5 to 7.5 and forms a reversible ester with bound l -lactate revealing the wavelength shift from λ = 300 nm to 288 nm in UV-VIS absorption spectrometry. In the spiked (2.5–20 mm ) samples of tomato puree, absorption peak increased as per l -lactate addition with the lower detection limit of 3.98 mm . l -lactate binds with a trigonal form of 3-boronate, thereby generating the tetrahedral complex. ZnO NPs stabilise the tetragonal complex. Nanosensor validated with standard HPLC. This method is useful for l -lactate detection and alternates to conventional techniques.     

Understanding e‐Government portal use in rural India: role of demographic and personality characteristics

Electronic government (e‐Government) is one of the most important ways to bridge the digital divide in developing countries. We develop a model of e‐Government portal use. We use various individual characteristics, namely demographics and personality, as predictors of e‐Government portal use. Specifically, our predictors were (1) gender, age, income and education; (2) the Big Five personality characteristics, i.e. extraversion, neuroticism, conscientiousness, agreeableness and openness to experience; and (3) personal innovativeness with information technology. We conducted a field study in a village in India. We collected data from over 300 heads of household. We found support for our model, with most variables being significant and explaining 40% of the variance in e‐Government portal use.     

Compaction and Sintering Behavior of Niobium Powder for Making Consumable Electrodes

Niobium consumable electrodes of 10?mm dia?×?50?mm length were prepared by cold isostaic pressing with compaction pressure of 125?C250?MPa. The compacts were sintered under vacuum at different temperatures in the range of 1000?C1800?oC. The CIPed and sintered electrodes were characterized with respect to chemical analysis, density, microstructure and bend strength. The results showed that there is a marginal improvement in density at a sintering temperature in the range of 1000?C1400?oC, while a significant improvement in density was observed at sintering temperature in the range of 1600?C1800?oC. The bend strength of sintered electrode was found to increase with increasing sintering temperature and that attains a highest value at a sintering temperature in the range of 1600?C1800?oC. Sintering at a temperature higher than 1400?oC leads to decrease in oxygen content of the electrodes. The oxygen content was decreased from 2000 to 500?ppm when electrode was sintered at 1800?oC.     

Ipomea carnea-based silver nanoparticle synthesis for antibacterial activity against selected human pathogens

The biosynthesis of silver nanoparticles (AgNps) has a wide range of applications, and here we develop a rapid synthesis using the leaf extract of Ipomea carnea. We demonstrated that 100?mL of a 1?mM silver nitrate solution was reduced to AgNps by 500?µL of I. carnea extract in 5?min and that one or more of the chemical constituents present in the extract acted as the reducing agent. Surface plasmon resonance peaks were observed from 410 to 440?nm for AgNps synthesised using the plant extract, and the peaks showed a characteristic blue shift with variation of pH from 2 to 8. Particle size analysis revealed the size of the AgNps to be from 30 to 130?nm, which was also confirmed by dynamic light scattering, atomic force microscopy and transmission electron microscopy. Additionally, the antibacterial effects of the AgNps were evaluated against selected human pathogens such as Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Klebsiella pneumoniae, Aeromonas hydrophila, Salmonella typhi, Proteus vulgaris and Pseudomonas aeruginosa. Finally, the AgNps were impregnated with a cellulose acetate membrane to form an antimycobacterial membrane. Antimycobacterial activity against a non-pathogenic Mycobacterium smegmatis showed that the AgNp-embedded membrane system has a zone of inhibition of 14?mm.     

Defect Characterization Using Pulsed Thermography

Infrared Thermography is one of the advanced NDE methods that is becoming attractive due to its ability to inspect non invasively large areas in short times and provide full field images in a non contact nature. While initially the method started as a qualitative technique for defect detection alone, with the advent of lock in and pulsed techniques, quantitative defect detection was made possible. While these techniques have been applied in case of ceramics and composites for defect quantification, defect sizing and quantification using these methods have not been systematically attempted in case of stainless steels. A systematic study has been undertaken to evaluate the accuracy of these empirical Pulsed Thermography (PT) techniques for defect size and depth estimation in type 316 L austenitic stainless steels. Theoretical modelling based on finite difference analysis using Thermo Calc 6L software has also been done and the results compared.     

A computationally efficient approach for hidden-Markov model-augmented fingerprint-based positioning

This paper presents a computationally efficient approach for mobile subscriber position estimation in wireless networks. A method of data scaling assisted by timing adjust is introduced in fingerprint-based location estimation under a framework which allows for minimising computational cost. The proposed method maintains a comparable level of accuracy to the traditional case where no data scaling is used and is evaluated in a simulated environment under varying channel conditions. The proposed scheme is studied when it is augmented by a hidden-Markov model to match the internal parameters to the channel conditions that present, thus minimising computational cost while maximising accuracy. Furthermore, the timing adjust quantity, available in modern wireless signalling messages, is shown to be able to further reduce computational cost and increase accuracy when available. The results may be seen as a significant step towards integrating advanced position-based modelling with power-sensitive mobile devices.     

Efficient Host-Guest Complexation of a Bisporphyrin Host with Electron Deficient Guests: Synthesis,Structure, and Photoinduced Electron Transfer

The encapsulation of 1,8-naphthalic anhydride (NAN), 9-dicyanomethylenefluorene (9-DCF), acenaphthenequinone (ANQ), and 4-chloro-7-nitrobenzofurazan (NBD-Cl) by diethylpyrrole-bridged bisporphyrin (H₄DEP) and its dizinc(II) analogue (Zn₂DEP) are employed to investigate the structural and spectroscopic changes within the bisporphyrin cavity upon substrate binding. Synthesis and X-ray structures of all four encapsulated host-guest complexes (H₄DEP⋅NAN, H₄DEP⋅9-DCF, Zn₂DEP⋅ANQ, and Zn₂DEP⋅NBD-Cl) are reported here. The binding constant calculations show strong 1 : 1 binding between the hosts (H₄DEP and Zn₂DEP) and the guests (NAN/9-DCF/ANQ/NBD-Cl). ¹H-NMR spectra also support the retention of the host-guest assemblies in solution. Negative and positive shifts of the reduction and oxidation potentials, respectively, indicate that it is difficult to reduce/oxidize the encapsulated complexes. The emission intensities of the bisporphyrins (H₄DEP and Zn₂DEP) are substantially quenched in all the complexes, owing to photoinduced electron transfer from the excited state of the bisporphyrins to guest molecules. All the experimental evidence is further substantiated by DFT calculations. Such an efficient electron transfer is only possible when the donor and the acceptor moieties are in close propinquity to each other, which eventually lowers the reorganization energy.     

Friction Buttering: A New Technique for Dissimilar Welding

This work offers a fresh perspective on buttering, a technique often considered for fusion welding of dissimilar metals. For the first time, buttering was attempted in solid state using friction deposition. Using this new “friction buttering” technique, fusion welding of two different dissimilar metal pairs (austenitic stainless steel/borated stainless steel and Al-Cu-Mg/Al-Zn-Mg-Cu) was successfully demonstrated. The results show that friction buttering can simplify a tough dissimilar welding problem into a routine fusion welding task.