Controlling the size distribution of nanoparticles through the use of physical boundaries during laser ablation in liquids

A simple, yet effective method of controlling the size and size distributions of nanoparticles produced as a result of laser ablation of target material is presented. The method employs the presence of physical boundaries on either sides of the ablation site. In order to demonstrate the potential of the method, experiments have been conducted with copper and titanium as the target materials that are placed in two different liquid media (water and isopropyl alcohol). The ablation of the target material immersed in the liquid medium has been carried out using an Nd:YAG laser. Significant differences in the size and size distributions are observed in the cases of nanoparticles produced with and without confining boundaries. It is seen that for any given liquid medium and the target material, the mean size of the nanoparticles obtained with the boundary-fitted target surface is consistently higher than that achieved in the case of open (flat) targets. The observed trend has been attributed to the plausible role(s) of the confining boundaries in prolonging the thermalisation time of the plasma plume. In order to ascertain that the observed differences in sizes of the nanoparticles produced with and without the presence of the physical barriers are predominantly because of the prolonged thermalisation of the plasma plume and not due to the possible formation of oxide layer, select experiments with gold as the target material in water have also been performed. The experiments also show that, irrespective of the liquid medium, the increase in the mean size of the copper-based nanoparticles due to the presence of physical boundaries is relatively higher than that observed in the case of titanium target material under similar experimental conditions.Comment: 24 pages, 9 figures, a part of this work has been published in Photonics Prague 2017, (Proc. SPIE 10603, Photonics, Devices, and Systems VII, 1060304) titled "A novel method for fabrication of size-controlled metallic nanoparticles

Performance of a Solar EV charger in the Pacific Island Countries

The unsustainable dependence of the Pacific Island Countries on imported fossil fuels and climate change concerns have made the region to look for alternative sources for energy. A major portion of fossil fuels goes towards transportation and it is imperative that other options such as biofuels and hybrids/ EVs are seriously explored. Considering the small distances involved, EVs can be profitably deployed in urban areas and also within the myriad tourist resorts spread across the Pacific islands. Solar PV based charging stations can play a major role in this endeavour. This paper describes the design and performance of first solar electric vehicle (EV) charging station in the Pacific Island Countries. The actual performance of this 2.6 kWp station is compared with the simulated results obtained using HOMER. The paper also looks at the way forward for the development of electric mobility in the region

Preliminary study on diminution level of RNA/DNA ratio in tissue of Labeo rohita by exposure to some endocrine disrupting compounds (EDCs)

Effects of EDCs particularly on RNA/DNA ratio are yet to be investigated to manage the effluents in natural waters. We investigated exposure effects of endocrine disrupting compounds (EDCs) phthalic acid ester (PAE) and hexachlorocyclohexane (HCH) on the RNA/DNA ratio in tissue of an Indian major carp Labeo rohita. Fish were exposed to pre-determined sublethal concentrations of phthalic acid ester (Di-methyl phthalate (DMP), di-butyl phthalate (DBP), and di-(2- ethylhexyl) phthalate (DEHP) and also HCH for determining the tissue RNA/DNA ratio after 30, 60 and 90 days of exposure in the doses of 0.2 mg L-1, 0.3 mg L-1, and 0.5 mg L-1 respectively. All these tested chemicals significantly (P0.05) inhibited RNA/DNA ratio. The ratio gradually significantly (P0.05) decreased after DEHP where it was 1.9±0.51 F1, 18=15.8 P=0.014 n=19; in case of DBP it was 1.92±0.62 F1, 20=6.5 P=0.012 n=19 and for HCH it was 0.94±0.21 F1, 18=18.08 P=0.0012 n=19 at treatments concentrations of 0.3 mg L-1 and 0.5 mg L-1, compared to control (2.9±0.2) after 90 days. However, there was no statistical significance (P0.05) in RNA/DNA ratio after the DMP (F1, 20=2.4 P=0.15n=21) treatment

Role of rainfall in the breeding of Labeo rohita (Ham.), Cirrhinus mrigala (Ham.), Catla catla (Ham.), at Damdama (Haryana), a semi-arid zone

The role of several environmental factors on the breeding and hatching of fish has been studied by many earlier investigators. Perfection in the hypophysation technique has helped to some extent in by-passing the environmental variables such as temperature, light and rain. With the use of a modern fish hatchery, it is possible to attain maximum success in breeding and hatching, even without rains; reference is given to studies carried out regarding the role of rainfall in the breeding of Labeo rohita, Cirrhinus mrigala, Catla catla

Novel PCR Assays Complement Laser Biosensor-Based Method and Facilitate Listeria Species Detection from Food

The goal of this study was to develop the Listeria species-specific PCR assays based on a house-keeping gene (lmo1634) encoding alcohol acetaldehyde dehydrogenase (Aad), previously designated as Listeriaadhesion protein (LAP), and compare results with a label-free light scattering sensor, BARDOT (bacterial rapid detection using optical scattering technology). PCR primer sets targeting the lap genes from the species ofListeria sensu stricto were designed and tested with 47 Listeria and 8 non-Listeria strains. The resulting PCR primer sets detected either all species of Listeria sensu stricto or individual L. innocua, L. ivanovii and L. seeligeri, L. welshimeri, and L. marthii without producing any amplified products from other bacteria tested. The PCR assays with Listeria sensu stricto-specific primers also successfully detected all species of Listeria sensu stricto and/or Listeria innocua from mixed culture-inoculated food samples, and each bacterium in food was verified by using the light scattering sensor that generated unique scatter signature for each species of Listeria tested. The PCR assays based on the house-keeping gene aad (lap) can be used for detection of either all species of Listeria sensu stricto or certain individual Listeria species in a mixture from food with a detection limit of about 104 CFU/mL

Cosmological Implications of Unimodular Gravity

We consider a model of gravity and matter fields which is invariant only under unimodular general coordinate transformations (GCT). The determinant of the metric is treated as a separate field which transforms as a scalar under unimodular GCT. Furthermore we also demand that the theory is invariant under a new global symmetry which we call generalized conformal invariance. We study the cosmological implications of the resulting theory. We show that this theory gives a fit to the high-z supernova data which is identical to the standard Big Bang model. Hence we require some other cosmological observations to test the validity of this model. We also consider some models which do not obey the generalized conformal invariance. In these models we can fit the supernova data without introducing the standard cosmological constant term. Furthermore these models introduce only one dark component and hence solve the coincidence problem of dark matter and dark energy.Comment: 18 pages, no figures, major revisions, substantial changes in analysis, results and conclusion

Growth of dense CNT on the multilayer graphene film by the microwave plasma enhanced chemical vapor deposition technique and their field emission properties

Catalyst assisted carbon nanotubes (CNTs) were grown on multilayer graphene (MLG) on copper and silicon substrates by the microwave plasma enhanced chemical vapor deposition technique. The transmission of the MLG was found to vary between 82 to 91.8% with the increase of deposition time. Scanning electron microscopy depicted that the MLG film survived at the deposition condition of CNTs with the appearance of the damaged structure due to the plasma. Growth of CNTs was controlled by adjusting the flow rates of methane gas. The density of carbon nanotubes was observed to increase with a higher supply of methane gas. It was observed that the field emission properties were improved with the increased density of CNTs on MLG. The lowest turn-on field was found to be 1.6 V mu m(-1) 1 accompanied with the highest current density of 2.8 mA cm(-2) for the CNTs with the highest density. The findings suggested that the field emission properties can be tuned by changing the density of CNTs

AN INTELLIGENT MOBILE-AGENT BASED SCALABLE NETWORK MANAGEMENT ARCHITECTURE FOR LARGE-SCALE ENTERPRISE SYSTEM

ABSTRACT Several Mobile Agent based distributed network management models have been proposed in recent time