INFLUENCE OF DESIGN AND OPERATIONAL PARAMETERS ON YIELD OF FULLERENES

Fullerene production by arc-discharge method using graphite electrodes has been studied with respect to influence of different design and operational parameters on fullerene yield in a constant arc fullerene reactor. The design parameters like reactor length, diameter, heat transfer area and operational parameters like voltage, current, pressure, coolant flow rate, graphite evaporation rate and electrode diameter etc. have been experimentally studied in detail to establish a relationship between these parameters and fullerene yield. All the parameters affecting the yield have been correlated by dimensional analysis and an equation to calculate the fullerene yield is derived. It was observed experimentally as well as by dimensional analysis that many favorable parameters for getting good yield are linked with other parameters which also get changed if the favorable parameters are changed and thus it is difficult to make a substantial change in the yield of fullerenes.  The relationship established between the yield and parameters is however useful in optimising fullerene yield in a reactor and also helpful in designing a futuristic fullerene reactor of improved yield and productivity. The fullerene yield from different designs of reactors is obtained in the range of 4% to 20%.     

Studies on Dehydration of Sapota (Achras zapota)

Sapota (Achras zapota) is a tropical fruit found in several parts of India. It is one of the most popular fruits besides mango, custard apple, and several others. Once ripe, it needs to be consumed within a couple of days due to the highly perishable nature of this exquisite fruit variety. The best way to increase the shelf-life is through the process of dehydration of peeled sapota. In the present study, the convective air drying of sapota pulp was carried out and compared with low-temperature drying techniques such as heat pump-assisted drying and freeze drying. The sapota paste was dried in a convective dryer to study the effect of operating parameters such as air temperature and air velocity. In addition, the effect of additives such as oat and wheat fibers and the paste thickness on drying was also studied. The critical analysis of dehydrated sapota was carried out in terms of water activity, sugar content, color, and rehydration ratio. The drying data were analyzed using Page's model and Newton's model on the basis of root mean square error (RMSE), reduced χ square (χ²) and correlation coefficient (R²).     

ATP-Dependent human erythrocyte glutathione-conjugate transporter. I. Purification, photoaffinity labeling, and kinetic characteristics of ATPase activity

Dinitrophenyl S-glutathione (DNP-SG) ATPase is a 38 kDa membrane protein expressed in erythrocytes and other tissues. Although stimulation of ATP hydrolysis catalyzed by DNP-SG ATPase has been demonstrated in the presence of several structurally unrelated amphiphilic ions, structural and functional properties of this protein have not been well-defined. In the present study, we have developed an improved protocol for the purification of DNP-SG ATPase and investigated its kinetic and substrate-binding properties. The purification procedure was based on highly specific elution of the 38 kDa protein from DNP-SG affinity resin in the presence of ATP. The protein could not be eluted using either ADP or adenosine-5'-[beta,gamma-methylene]triphosphate (methylene-ATP), a nonhydrolyzable analogue of ATP. Doxorubicin (DOX), a weakly basic anthracycline chemotherapy agent, was found to be the preferred activator for stimulation of ATP hydrolysis by the enzyme. ATP binding to the enzyme was demonstrated using 8-azido-ATP photoaffinity labeling and binding of trinitrophenyl (TNP)-ATP, a fluorescent analogue of ATP. The photoaffinity labeling of DNP-SG ATPase (38 kDa) was saturable with respect to 8-azido ATP (Kd = 2 microM), indicating that the enzyme was capable of specific and saturable binding to ATP. DNP-SG binding was evident from the purification procedure itself and was also demonstrable by quenching of tryptophan fluorescence. Results of quenching of tryptophan fluorescence as well as radioactive isotope-binding studies indicated that DOX was bound to the purified protein as well.     

Compact multiband planar monopole antenna for Bluetooth,LTE, and reconfigurable UWB applications including X‐band and Ku‐band wireless communications

In this article, a small‐printed Bluetooth/LTE/UWB/X‐band/Ku‐band monopole antenna with high rejection triple band‐notch is presented. Notched bands include WiMAX (IEEE802.16 3.30‐3.80 GHz), WLAN IEEE802.11a/h/j/n (5.15‐5.35 GHz, 5.25‐5.35 GHz, 5.47‐5.725 GHz, and 5.725‐5.825 GHz), and downlink satellite system (7.1‐7.9 GHz). By including inverted T‐shaped stub and etching two C‐shaped slots on the radiating patch, triple band‐notch function is obtained with measured high band rejection (VSWR = 14.59 at 3.69 GHz, VSWR = 39.40 at 5.42 GHz, and VSWR = 6.43 at 7.57 GHz) and covers a UWB useable fractional bandwidth of 157.75% (2.285‐19.35 GHz = 17.065 GHz). Reconfigurable characteristics are obtained using PIN diodes, which control the individual notched bands. Proposed antenna is printed on Rogers RT/duroid5880 substrate with compact dimensions of 20 × 22 mm². Proposed antenna finds its applications for Bluetooth, LTE, UWB, other multiple wireless applications for close range radar (8‐12 GHz) in X‐band, and satellite communication in Ku‐Band with omnidirectional pattern in H‐plane.     

High Diversity Gain MIMO-Antenna for UWB Application with WLAN Notch Band Characteristic Including Human Interface Devices

Wireless Personal Communications - In this paper, a UWB–MIMO antenna with the WLAN band-notch (5.1–5.85 GHz) characteristic is offered. This antenna consists of two radiated...     

Investigation on carbon nanomaterials: Coaxial CNT-cylinders and CNT-polymer composite

The macroscopic coaxial carbon cylinders (dia. ∼0.5 cm with varying lengths, ∼ 7–10 cm) consisting of aligned carbon nanotube (CNT) stacks have been prepared by controlled spray pyrolysis method. The coaxial carbon cylinders of CNT stacks have been formed directly inside the quartz tube. Another study is done on multi-walled CNTs (MWNTs)-polymer (e.g. polyethylene oxide (PEO), polyacrylamide (PAM)) composite films. We have investigated the structural, electrical and mechanical properties of MWNTs-PEO composites. Composites with different wt% (between 0 and 50 wt% of MWNTs) have been prepared and characterized by the scanning electron microscopic technique. Enhanced electrical conductivity and mechanical strength were observed for the MWNTs-PEO composites. We have also studied the electrical property of MWNTs-PAM composite films.     

Synthesis of polymer stabilized silver and gold nanostructures

This review article is focused on the various approaches that have been made to synthesize metal nanoparticles with predetermined shape, size, and fair stability. Due emphasis has been given on polymer stabilized nanoparticles. In addition use of other varieties of stabilizers like inorganic salts, organic compounds, organic solvent, biological molecules, etc. have also been discussed. Finally, formation of two and three-dimensional nanostructures like nanowires, nanodiscs, nanoprisms has also been revealed.     

Thermo-hydraulic performance investigation of solar air heater duct having staggered D-shaped ribs: Numerical approach

The thermohydraulic performance (THP) of a solar air heater (SAH) duct with staggered D-shaped ribs as roughness geometry is examined in this work using three-dimensional numerical investigation. The investigation is carried out at roughness parameters of radius of rib to transverse pitch (r/P_tv) ratios of 0.1–0.35 and longitudinal pitch to radius of rib (P_lg/r) ratios of 4–10 under varied operating circumstances of Reynolds number (Re) from 10,200 to 20,200. The maximum Nusselt number (Nu) is obtained to be 81.3 at Re of 20,200, r/P_tv as 0.1, and P_lg/r as 4. In contrast, the maximum friction factor (f) is obtained to be 0.0169 at Re of 10,200, r/P_tv as 0.35, and P_lg/r as 4. In the range of parameters examined, the maximum enhancement in Nusselt number (Nu/Nu_s) is observed to be 1.35 at an optimal parameter of r/P_tv as 0.1, P_lg/r as 4, and Re as 10,200. Correspondingly, the enhancement in the friction factor (f/f_s) at this optimum parameter is 1.87. The maximum value of the THP parameter is found to be 1.1 at the same optimum range of parameters. In further analysis, correlations were developed for Nusselt number (Nu) and friction factor (f) in terms of r/P_tv, P_lg/r, and Re with a deviation of ±2% and ±1.5%, respectively.