ZnO anchored graphene hydrophobic nanocomposite-based bulk heterojunction solar cells showing enhanced short-circuit current

Hydrophobic and surfactant-free ZnO nanoparticles and ZnO decorated graphene nanocomposite (Z@G) with narrow and uniform size distribution were synthesized by a time-efficient microwave-assisted hydrothermal reaction that can be used specifically for application in hybrid photovoltaics. The synthesized ZnO nanoparticles and Z@G nanocomposite showed stable and clear dispersion in chloroform and methanol (with volume ratio of 9 : 1) and chloroform and ethanol (volume ratio 9 : 1). Being hydrophobic, these inorganic samples blend very well with organic polymer solution in chlorobenzene, which is a prerequisite to cast smooth and undisrupted film for hybrid solar cell application. The introduction of these hydrophobic nanoparticles into PCPDTBT: PCBM-based bulk-heterojunction polymer solar cells resulted in significant improvement in solar cell J-V characteristics with enhancement in open circuit voltage (VOC), short circuit current density (JSC) and thereby overall improvement in cell efficiency. With the optimization of the weight ratio of polymer, fullerene and synthesized ZnO nanoparticles/Z@G nanocomposite, the power conversion efficiencies 1.76% and 3.65% were achieved

Economic impact of dissemination of management strategies for sucking insect pests on transgenic cotton in Punjab, India

Integrated pest management (IPM) strategies for the management of sucking insect pests were disseminated in 36 villages of three districts of Punjab during 2008 to 2010. Adoption of IPM strategies led to reduction in the population of jassid, whitefly and mealybug in IPM villages. Mean population of jassid was 0.62 and 1.60 nymphs per three leaves, whitefly 1.11 and 2.53 adults per three leaves and mealybug 0.53 and 1.03 per 2.5 cm of central shoot in IPM and non-IPM villages, respectively. Mean population of spiders, chrysoperla, coccinellids and predatory bugs was 0.65, 0.13, 0.15 and 0.04 in IPM villages and 0.29, 0.09, 0.06 and 0.00 per plant in non-IPM villages, respectively. IPM strategies resulted in the 47.69 and 50.56 per cent reduction in number of spray and cost of spray in IPM villages over non-IPM villages. The average cost of cultivation was Rs. 21324 ha−1 in IPM villages, as compared to non-IPM villages (Rs. 23774.67 ha−1). Average seed cotton yield in IPM villages was 2333 kg ha−1 in comparison to non-IPM villages (1959.67 kg ha−1) and average net return in IPM villages was Rs. 57194 ha−1, which was Rs. 15709 more than non-IPM villages

Measurement of the analyzing power of proton-carbon elastic scattering in the CNI region at RHIC

The single transverse spin asymmetry, A_N, of the p-carbon elastic scattering process in the Coulomb Nuclear Interference (CNI) region was measured using an ultra thin carbon target and polarized proton beam in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). In 2004, data were collected to calibrate the p-carbon process at two RHIC energies (24 GeV, 100 GeV). A_N was obtained as a function of momentum transfer -t. The results were fit with theoretical models which allow us to assess the contribution from a hadronic spin flip amplitude.Comment: Contribution to the proceedings of the 16th International Spin Physics Symposium, spin2004 (Trieste

Microwave shielding properties of Co/Ni attached to single walled carbon nanotubes

Cobalt/nickel nanoparticles attached to single-walled carbon nanotubes (Co/Ni@SWCNTs) were prepared by dc-arc discharge technique. Co/Ni@SWCNTs were characterized by scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and energy dispersive X-ray analysis techniques. HRTEM results confirmed attachment of magnetic nanoparticles onto SWCNTs having 1.2 nm diameter. A microwave shielding effectiveness value of 24 dB (blocking >99% radiation) by a 1.5 mm thick sample in the frequency range of 12.4-18 GHz was observed. In order to understand the mechanism of shielding, dielectric andmagnetic attributes of the shielding effectiveness of Co/Ni@SWCNTs have been evaluated. Eddy currents and natural resonances due to the presence of magnetic nanoparticles, electronic polarization and their relaxation, interfacial polarization and unique composition of the shield contributed significantly in achieving good shielding effectiveness. The observed microwave shielding crossed the limit required for commercial applications which suggests that these nanocomposites are promising microwave shielding materials in the Ku band

Disk-Jet Connection in Cygnus X-3

We present the results of a detailed correlation study between the soft X-ray, hard X-ray, and radio emission (obtained from RXTE ASM, BATSE, and GBI observations, respectively) of the bright radio emitting Galactic X-ray binary Cygnus X-3. We detect a very strong positive correlation between the soft X-ray and radio emission during the low-hard and minor flaring periods of the source, and an anti-correlation between the soft and hard X-ray emissions. We present statistical arguments to suggest that the anti-correlation between the radio and hard X-ray emission, reported earlier, is primarily due to their correlation and anti-correlation, respectively, with the soft X-ray emission. We make a wide band X-ray spectral study using the pointed RXTE observations and detect a pivotal behaviour in the X-ray spectrum. We argue that this X-ray spectral pivoting is responsible for the anti-correlation between the soft and hard X-ray emissions. The strong correlation between the soft X-ray and radio emission suggests a close link between the accreting mechanism, plasma cloud surrounding the compact object and the radio emission.Comment: Accepted in A&A Letters. Major revioson of discussion, minor revision of tables and figure

Spectral differences between the radio-loud and radio-quiet low-hard states of GRS 1915+105: possible detection of synchrotron radiation in X-rays

The Galactic microquasar GRS 1915+105 exhibits several episodes of steady X-ray emission characterized by a hard power-law spectrum and intense Quasi Periodic Oscillations. It is known that there are two types of such low-hard states, one with steady radio emission and the other without any significant radio emission. We present the results of a detailed X-ray spectroscopic study of GRS 1915+105, using data from the Rossi X-ray Timing Explorer obtained during various episodes of the low-hard states of the source. We show that there are distinct X-ray spectral differences between the radio-quiet and radio-loud low-hard states of the source. The X-ray spectra of the radio-quiet low-hard state is best described by a model consisting ofa multicolor disk-blackbody and a Comptonized component, whereas the X-ray spectra of radio-loud low-hard state requires a model consisting of three components: a multicolor disk-blackbody, a Comptonized component and a power-law, for statistically and physically acceptable fits. We attempt to model the presence of this additional power-law component as due to synchrotronradiation which is responsible for the radio and infrared radiation from thesource. We show that a simple adiabatically expanding jet model for the synchrotron radiation can account for the observed X-ray flux for reasonable values of the magnetic field and the mass outflow rate. This is the first report of detection of the synchrotron radiation in the X-ray band for this source.Comment: 9 pages 5 figures, Accepted in A&

Study of the Largest Multiwavelength Campaign of the Microquasar GRS 1915+105

We present the results from a multiwavelength campaign of GRS 1915+105 performed from 2000 April 16 to 25. This is one of the largest coordinated set of observations ever performed for this source, covering the wide energy band in radio (13.3-0.3 cm), near-infrared (J-H-K), X-rays and Gamma-rays (from 1 keV to 10 MeV). During the campaign GRS 1915+105 was predominantly in the "plateau" (or low/hard) state but sometimes showed soft X-ray oscillations: before April 20.3, rapid, quasi-periodic (~= 45 min) flare-dip cycles were observed. The radio flares observed on April 17 shows frequency- dependent peak delay, consistent with an expansion of synchrotron-emitting region starting at the transition from the hard-dip to the soft-flare states in X-rays. On the other hand, infrared flares on April 20 appear to follow (or precede) the beginning of X-ray oscillations with an inconstant time delay of ~= 5-30 min. This implies that the infrared emitting region is located far from the black hole by >~ 10E13 cm, while its size is <~ 10E12 cm constrained from the time variability. We find a good correlation between the quasi-steady flux level in the near-infrared band and in the X-ray band. From this we estimate that the reprocessing of X-rays, probably occurring in the outer parts of the accretion disk, accounts for about 20-30% of the observed K magnitude in the plateau state. The OSSE spectrum in the 0.05-10 MeV band is represented by a single power law with a photon index of 3.1 extending to ~1 MeV with no cutoff. The power-law slope above ~30 keV is found to be very similar between different states in spite of large flux variations in soft X-rays, implying that the electron energy distribution is not affected by the change of the state in the accretion disk.Comment: 31 pages, 11 figures. Accepted for publication in ApJ, vol. 571, 2002. Minor corrections. Figure 2 is revised (numbers on the top axis are corrected). References are update