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Duck production has the potential to play a major role in agricultural economy. Asian countries alone contribute 84.2% of total duck meat produced in the world. Driven by the demand of processed foods among consumers, the global duck meat market is expected to grow at a steady pace, reaching a value of about $11.23 billion in the coming years. Duck meat has higher muscle fibre content in breast meat compared to chicken, and is considered as red meat. Moreover, due to a higher fat content (13.8%) than chicken and a stronger gamey flavour, duck meat can be less appreciated by the consumer. Development and diversification of ready-to-eat duck meat products is expected to increase consumption levels. Hence, the status of duck meat production, physicochemical properties, processing, including traditional products, and development of novel value-added ready-to-eat products from spent duck meat is discussed in detail to explore its importance as an alternative to chicken.
We describe a study of the E–W-trending South Wagad Fault (SWF) complex at the eastern part of the Kachchh Rift Basin (KRB) in Western India. This basin was filled during Late Cretaceous time, and is presently undergoing tectonic inversion. During the late stage of the inversion cycle, all the principal rift faults were reactivated as transpressional strike-slip faults. The SWF complex shows wrench geometry of an anastomosing en échelon fault, where contractional and extensional segments and offsets alternate along the Principal Deformation Zone (PDZ). Geometric analysis of different segments of the SWF shows that several conjugate faults, which are a combination of R synthetic and R’ antithetic, propagate at a short distance along the PDZ and interact, generating significant fault slip partitioning. Surface morphology of the fault zone revealed three deformation zones: a 500 m to 1 km wide single fault zone; a 5–6 km wide double fault zone; and a c. 500 m wide diffuse fault zone. The single fault zone is represented by a higher stress accumulation which is located close to the epicentre of the 2001 Bhuj earthquake of Mw 7.7. The double fault zone represents moderate stress at releasing bends bounded by two fault branches. The diffuse fault zone represents a low-stress zone where several fault branches join together. Our findings are well corroborated with the available geological and seismological data.
In this note we wish to report briefly the observation of sudden changes in the intensity of Sco X-1 by a factor of about 3 recorded in the energy interval 29.9–52.3 keV on December 22, 1968 between 04 h 27 m and 05 h 53 m UT. The observation was made with an X-ray telescope flown in a balloon from Hyderabad, India. The balloon was launched at 0200 hr UT and reached the ceiling of 7.5 g/cm2 of residual atmosphere at 0435 hr UT. The X-ray telescope consisted of a NaI(T1) crystal with an area of 97.3 cm2 and thickness 4 mm, surrounded by both active and passive collimators. The telescope was mounted on an oriented platform which was programmed to look in four specified directions successively, of azimuths, Φ=0°, 110°, 180° and 310° (Φ=0° being North and Φ=90°, West), spending about 4 min in each direction during a cycle of period of about 16 min. The axis of the telescope was inclined at an angle of 32° with respect to the zenith. A pair of crossed flux gate magnetometers provided information every 8.2 sec on the azimuth of the telescope. The pulse heights from the X-ray detector were sorted into several channels extending from 10 to 120 keV. An Am241 source came into the field of view of the telescope once in 15 min for about 30 sec to provide in-flight calibration of the detector. The meridian transit of Sco X-1 was at 0454 hr UT. Just before the balloon reached the ceiling Sco X-1 was in the field of view of the telescope for 3 min and 41 sec. After the balloon reached ceiling, Sco X-1 was in the field of view of the telescope on five occasions between 0443 and 0553 hr UT. During the last observation, however, the balloon had lost altitude by about 1 g/cm2. The excess counts due to Sco X-1 were obtained by subtracting the counting rates corresponding to the North direction which did not include any known X-ray sources. The observation on Sco X-1 in the 1st cycle was made while the balloon was still ascending and consequently the interposed grammage was changing from 10.5 to 9.7 g/cm2. However, for the energy range under consideration, the change in the background counting rate was not significant and there cannot be any doubt regarding the genuineness of the excess counts recorded.
In this paper we report on our observations of hard X-rays from several X-ray sources in the energy range 20–120 keV. The results were obtained from the data collected during two balloon flights made from Hyderabad, India (latitude 17.6°N, longitude 78.5°E). The first flight was made on April 28, 1968, and the balloon reached a ceiling of about 5.3 g cm−2 residual atmosphere and floated from 0230 to 0800 hrs. IST (Indian Standard Time). The second balloon was launched on December 22, 1968 and floated at about 7.5 g cm−2 of residual air from 1000 to 1130 hrs. IST.
In this paper we present observations of the diffuse background X-rays in the energy range 20–120 keV, based on two balloon experiments carried out from Hyderabad (latitude 17.6°N, longitude 78.5°E), India. The flights were made on April 28, 1968 and December 22, 1968. The detector used was a NaI(Tl) crystal of effective area 97.3 cm2 and thickness 4 mm. The crystal was surrounded both by active and passive collimators. The passive collimator was a cylindrical graded shield of lead, tin, and copper, and the active collimator was a plastic scintillator surrounding the shield. The FWHM of the telescope was 18.6° and the geometrical factor for isotropic radiation 13.2 cm2 sr. The pulses from the NaI crystal were sorted into ten contiguous channels extending from 17 to 124 keV. An Am241 source came into the field of view of the telescope periodically and provided in-flight calibration of the detector. All the information was recorded on photographic film.
The work presents a comparative study on GaN/AlGaN type-II heterostructures grown on c-plane Al2O3 and Si (111) substrates by Plasma Assisted Molecular Beam Epitaxy. The in-depth structural characterizations of these samples were performed by High-Resolution X-Ray Diffraction, X-ray Reflectivity and Field Emission Scanning Electron Microscopy. The in-plane and out-of plane strains were determined from measured c- and a-lattice parameters of the epilayers from reciprocal space mapping of both symmetric triple axis (002) and asymmetric grazing incidence (105) double axis mode. The mosaicity parameters like tilt and correlation lengths were also calculated from reciprocal space mapping. Moreover, the twist angle was measured from skew symmetric off axis scan of (102), (103), and (105) planes along with (002) symmetric plane. The defect density were measured from the full width at half maxima of skew symmetric scan of (002) and (102) reflection planes. Also, the strained states of all the layers were analyzed and corresponding Al mole fraction was calculated based on anisotropic elastic theory. The thicknesses of the layers were measured from simulation of the nominal structure by fitting with X-ray Reflectivity experimental curves and also by comparing with cross sectional Field Emission Scanning Electron Microscopy micrographs.
In this paper we have studied the dia and paramagnetic susceptibilities of the holes in ultrathin films of dilute magnetic materials in the presence of a quantizing magnetic field and compared the same with that of the bulk specimens under magnetic quantization for the purpose of relative comparison. It is found, taking Hg1−xMnxTe and Cd1−xMnxSe as examples, that both the susceptibilities increase with decreasing film thickness and increasing surface concentration in oscillatory Manners. The numerical values of the susceptibilities in ultrathin films of dilute magnetic materials are greater than that of the bulk and the theoretical analysis is in agreement with the experimental data as reported elsewhere.
Highly efficient Pt-TiO2 composite photoelectrodes were synthesized by combining two novel deposition methods: ACVD and a room temperature RF (radio frequency) magnetron sputtering method. A room temperature RF magnetron sputtering method allowed uniform deposition of Pt nanoparticles (NPs) onto the as-synthesized nanostructured columnar TiO2 films by ACVD. Pt NP sizes from 0.5 to 3 nm demonstrating a high particle density (>1012 cm−2) could be achieved by varying deposition time with constant pressure and power intensity. As-synthesized Pt-TiO2 films were used as photoanodes for water photolysis. Pt nanoparticles deposited onto the TiO2 film for 20s produced the highest photocurrent (7.92 mA/cm2 to 9.49 mA/cm2) and maximized the energy conversion efficiency (16.2 % to 21.2 %) under UV illumination. However, as the size of Pt particles increased, more trapping sites for photogenerated electron-hole pairs decreased photoreaction.
In the development of novel materials for enhanced photovoltaic (PV) performance, it is critical to have quantitative knowledge of the initial performance, as well as the performance of these materials over the required 25-year lifetime of the PV system. Lifetime and degradation science (L&DS) allows for the development of new metrology and metrics, coupled to degradation mechanisms and rates. Induced absorbance to dose (IAD), a new metric being developed for solar radiation durability studies of solar and environmentally exposed photovoltaic materials, is defined as the rate of photodarkening or photobleaching of a material as a function of total absorbed solar radiation dose. In a reliability engineering framework, these quantitative degradation rates can be determined at various solar irradiances making possible real time and accelerated testing. The potential to predict power losses in a photovoltaic system over time caused by the accumulation of this kind of degradation can be calculated for real time applications or extrapolated for accelerated exposure conditions. Three formulations of poly (methyl methacrylate) (PMMA) used for mirror augmented PV systems were analyzed for the changes in IAD after accelerated testing.
A thin metal film with nano-apertures, called “nano-mesh electrode,” generates near-field lights near the electrode. We investigated carrier excitations in semiconductors by the near-field light. Finite-difference time-domain (FDTD) method revealed that when the infrared light irradiates the Au nano-mesh electrode on Ge, near-field lights are generated and absorbed in the surface region of the Ge. In order to measure the photocurrent involved by near-filed lights, we fabricated a Schottky cell and applied a Au nano-mesh electrode on the n-type Ge. The efficiency of the Schottky cell with the Au nano-mesh electrode improved in infrared region compared to plain the Au-film Schottky cell. The agreement between theoretical simulations and experiments indicates that near-field lights enhance the carrier excitation in the semiconductor.
Comparative studies have been carried out on the performance of the photovoltaic devices with dissimilar shapes of the InN nanostructures fabricated on p-Si (100). The devices fabricated with the nanodots show a superior performance compared to the devices fabricated with the nanorods. The discussions have been carried out on the superior junction property, larger effective junction area and inherent random pyramidal topographical texture of the cell fabricated with nanodots. Such single junction devices exhibit a promising fill factor and external quantum efficiency of 38% and 27%, respectively, under concentrated AM1.5 illumination.
Surface plasmon enhanced InAs/GaAs quantum dot solar cells are reported. Light trapping by metallic nanostructures offers the potential to realize high efficient quantum dot based intermediate band solar cells. Both Au and Ag nanoparticles spherical metal nanoparticles are synthesized by the salt reduction method. The large area coupling of metal nanoparticles and quantum dot solar cell surface is carried out by using 1,3-propanedithiol as linker molecules. The conversion efficiency of the solar cells has been increased from 9.5% to 11.6% after deposition of Au nanoparticles and from 9.5 to 10.9% after incorporating Ag nanoparticles. The conversion efficiency enhancement is mainly as a result of improved photocurrent due to enhanced forward scattering from the plasmonic nanostructures.
This work investigates a novel method to enhance light trapping within polycrystalline silicon (poly-Si) thin films for photovoltaic applications. The method combines the use of hydrogen ion implantation for creation of surface textures in poly-Si thin films and the deposition of silver nanostructures on the textured surface. Poly-Si thin films were prepared by solid phase crystallization of amorphous silicon (a-Si) layer deposited on a SiO2/Si substrate. The a-Si was annealed at various temperatures 600 -1050 °C for 48 hours to grow grains of different size in p-Si, as confirmed by x-ray diffraction (XRD) measurements. These samples were then implanted with 20-keV hydrogen ions to a dose of 1017/cm2, and some with an additional implant with 90-keV argon ions to a dose 5×1015 /cm2. Following implantation, these samples were annealed in an Ar ambient at different temperatures. Surface blistering effects were observed using an optical microscope. Optical specular reflection measurements in the spectral range 400-1100 nm indicated that the reflectance of the samples with higher blistering had decreased remarkably from 40% to 10%. Lastly, the poly-Si samples with various textures were deposited with silver thin film followed by annealing in nitrogen ambient for forming Ag nanostructures on textured poly-Si surfaces. Scanning Electron Microscope (SEM) was used to image the surface structures. The formation of Ag nanoparticles on the poly-Si surface, with textures created by implantation followed by low-temperature annealing (e.g., 400 °C), can significantly reduce light reflection as opposed to the case with Ag nanoparticles formed on an un-textured, poly-Si surface.
Low dimensional structures like quantum dots (QDs) offers the the ability to tune the absorption properties of standard semiconductor materials. However, QDs are relatively weak light absorbers and hence may benefit significantly from coupling with plasmonic modes in nearby metal structures. In the case of a Si QD absorber layer for photovoltaic applications, enhanced absorption would lead to improved power conversion efficiency. Silver metal nanoparticles (MNPs) were deposited on Si QD structures using the self-assembly method of evaporation and annealing. Room temperature photoluminescence (PL) measurements were used to study the surface plasmon (SP) enhanced emission from the samples. The results were compared to conventional metal back reflectors. Enhanced surface plasmon coupled emission (SPCE) from Si QDs in the vicinity of silver metal nanoparticles (MNPs) is observed with a good correlation between the enhancement and the resonance excitation. Quenching was observed from the same emitter layers placed in close proximity to thin flat silver reflector layers, indicating the importance of the spacer layer between a metal layer and the quantum dots in optimising enhancement. The results have implications for the design of SP-enhanced QD solar cells.
A plasmonic back reflector has been fabricated for light-trapping application in thin film Si photovoltaic devices. The back reflector comprises of a 2D array of self-organized Ag NPs separated from a planar Ag mirror by a ZnO layer deposited by atomic-layer deposition. The diffuse reflectance and parasitic absorption losses can be modulated by varying the ZnO thickness. A maximum diffuse reflectance peak value of 30% at 950 nm, with a bandwidth of 400nm, is observed for ∼100 nm diameter NPs at a distance of 50 nm from the Ag mirror. Finite-difference time-domain simulations of a 100nm Ag sphere near a mirror were used to understand the experimentally observed trends in diffuse reflectance and parasitic absorption, with distance from the mirror. Particles very close to the mirror can couple to delocalized surface plasmons or exhibit Fano resonance effects, thereby increasing parasitic absorption. Particles situated away from the mirror are influenced by driving-field effects due to the interaction of incident and reflected photons, which modulate the scattering cross-section.
The Lambertian limit represents a benchmark for the enhancement of the effective path length in solar cells, which is important as soon as the absorption length exceeds the absorber thickness. In previous publications it has been shown that either extremely thick or extremely thin solar cells can be driven close to this limit by exploiting up to date photon management. In this contribution we show that the Lambertian limit can also be achieved with thin-film solar cells based on amorphous silicon for practically relevant absorber thicknesses. Departing from superstrates, which are currently incorporated into state-of-the-art thin-film solar cells, we show that their topology has simply to be downscaled to typical feature sizes of about 100 nm in order to achieve this goal. By systematically studying the impact of the modulation height and the lateral feature sizes of the incorporated textures and of the absorber thickness we are able to deduce intuitive guidelines how to approach the Lambertian limit in randomly textured thin-film solar cells.
ZnO nanorods were grown homogenously and vertically on ITO using electrochemical techniques. The physical properties of the nanorods were characterized using SEM and optical absorption. The electrical conductivity, deduced using STM at different tip heights, and was found to be 20 Ω-cm with a carrier concentration of 3x1015 cm-3.The results show that electrochemically grown ZnO nanorods have electrical properties suitable for use in electronic devices such as solar cells and transistors. A-Si:H p-i-n solar cells were then deposited after the fabrication on the ZnO on ITO-coated substrates. The results show that the textured solar cell performance was 30% higher than the planar solar cell.
Reported is the photoluminescence enhancement due to surface plasmon from the metallic nanoparticles that are linked to the surface of a GaAs capped InAs quantum dots. In this study, spherical silver (Ag) nanoparticles are investigated where the different densities of Ag nanoparticles are deposited on four InAs/GaAs quantum dot samples. The PL enhancement due to Ag nanoparticles has been observed to be improved with increasing nanoparticle density. The photoluminescence enhancement is interpreted in terms of enhanced scattering from the surface plasmon excited in the Ag nanoparticles.
The drive to reduce the thickness of solar cells is putting ever greater demands on light-trapping techniques. Techniques are required to improve absorption of light within the semiconductor, while not adversely affecting the electrical properties of the device. Conventional diffraction gratings can scatter visible and near-infrared photons into large angles, which get trapped in the silicon layer by total internal reflection. However, diffraction gratings typically have large feature sizes and so increase the overall surface area of a solar cell compared to the planar case. A periodic arrangement of metal nanoparticles acts as a diffraction grating, but an over-coated semiconductor will have a similar surface area to a planar layer due a combination of a low particle height and low surface coverage.
Random arrays of identical metal nanoparticles feature Lorentzian scattering peaks that can be tuned by modifying the size and shape of the particle. Periodic arrays have much more complicated scattering peaks, due to the enhancement and suppression of scattering at different wavelengths caused by the constructive and destructive interference between each nanoparticle. In effect the scattering spectrum of the individual nanoparticle is modified by the diffractive orders of the array, and so both parameters must be optimized together.
We have studied periodic arrays of metal nanoparticles fabricated using electron-beam lithography, and characterised their reflectance properties. The optical properties of the fabricated arrays were found to be in good agreement with finite-difference time-domain (FDTD) simulations. Au and Al nanoparticles are found to have a strong scattering effect and Al nanoparticles are also shown to exhibit an anti-reflection effect in combination with scattering. This work is focused on verifying that FDTD simulations can accurately model metal nanoparticle arrays and then extending the simulations to determine the previously unknown transmittance characteristics of metal nanoparticle arrays on silicon.
The use of plasmonic nanoparticles as light scattering elements for light trapping in solar cells is studied. From theoretical considerations it follows that Ag particles with a diameter on the order of 100 nm possess ideal light scattering properties. It is demonstrated that these particles can be fabricated using the selective aerosol deposition technique. Because this newly developed technique provides excellent control over critical parameters such as particle size and surface coverage it is a valuable tool for optimizing plasmonic solar cells. The initial experiments show that embedding Ag particles with a diameter of 180 nm into amorphous silicon solar cells enhances the current output.