Efficacies of inocula on the startup of anaerobic reactors treating dairy manure under stirred and unstirred conditions

Inocula play an important role in anaerobic reactor startup by balancing the populations of Syntrophobacter and methanogens. Such balances make syntrophic metabolism thermodynamically feasible in anaerobic digestion. In this study, the effect of inocula on the performance of dairy manure digestion was investigated by analyzing the change in volatile fatty acids (VFA), total solids (TS), volatile solids (VS), specific biogas production (SGPR), and specific methane production (SPMP) as well as scanning and transmission electron micrographs. The study was performed at four treatments. Treatment one was granular sludge (GM); treatment two was non-granular sludge (SM); treatment three was mixed culture from an anaerobic lagoon (LM); while the fourth treatment (the control denoted MM) did not receive any exogenous inocula. In addition, stirred and unstirred conditions were maintained in the reactors to determine their effect on reactor startup. Performance ranking based on the SGPR and SPMP of treatments (in descending order) was: GM, SM, LM and MM under stirred conditions. Under unstirred conditions, performance ranking (also in descending order) was: SM, GM, LM, and MM. Results of the examination of microcolonies in the granular, non-granular sludge, and dairy manure suggest that syntrophic juxtaposition of methanogens and Syntrophobacter in granular inoculum was common while it was less visible in non-granular sludge, and completely absent in dairy manure.     

Fe–EBT Chelate Complex: A Novel Mean for Growth of α-FeOOH and γ-Fe_2O_3 Nanostructures

Acicular goethite(a-Fe OOH) and worm-like maghamite(γ-Fe_2O_3) nanostructures have been prepared adopting a novel route, using Na2[Fe(HL)2(H2O)2] chelate complex in alkaline medium. It is found that concentration of hydrated Fe(III) ions increased with increasing temperature, which later play a key role in generation of different phases of iron oxide. Phase and morphology of the products are investigated using XRD, FTIR, SEM, and TEM analysis. Using UV–Vis spectra, various electronic transitions of goethite and maghamite particles are examined. Maghamite nanostructures exhibit superparamagnetic property at room temperature. On the basis of experimental observations and analytical data, growth mechanism of the nanostructures is discussed.     

Structural and electrical studies of Ba5LaTi3V7O30 compound

The ferroelectric ceramic Ba₅LaTi₃V₇O₃₀ has been synthesized by solid-state reaction technique. Preliminary X-ray structural analysis confirmed a single-phase formation (orthorhombic crystal system) of the compound. Surface morphology of the compound was studied by scanning electron microscopy (SEM). Detailed studies of electrical properties (i.e., dielectric constant, loss tangent, ac and dc conductivity) as a function of temperature (RT - 773?K) at four different frequencies, 1?kHz, 10?kHz, 100?kHz and 1?MHz show ferroelectric—paraelectric phase transition of the compound. The impedance spectra show two distinctly separated regions in wide temperature range corresponding to grain boundary and grain interior contributions. The activation energy has been evaluated from ac conductivity and dc conductivity following Arrhenius equation is 0.15?eV at 1?MHz and 0.28?eV, respectively. The temperature dependence of electrical conductivity shows that the conductivity increases with increase in temperature suggesting that the compounds have a negative temperature coefficient of resistance (NTCR) behaviour. The conductivity pattern shows that it is strongly frequency dependent and obeys Jonscher’s power relation.     

SbSI Films for Ferroelectric Memory Applications

Films of ferroelectric antimony sulphoiodide (SbSI) were grown on platinized silicon substrates by pulsed laser deposition (PLD). The films were grown at room temperature and later annealed at 200-250 C in air for crystallinity. The Curie temperature (T C ) of these films was 17-21 C, whereas the peak dielectric constant was up to 5000. These films showed nonzero remnant polarization above T C up to a temperature of 40 C and a low leakage current density of around 10 m 6 A/cm 2 at 2V. SbSI films were integrated with colossal magnetoresistive La 0.67 Ca 0.33 MnO 3 (LCMO) thin film, which acts as a p-type semiconductor. The LCMO-SbSI heterostructures, with SbSI as a ferroelectric gate, showed a channel modulation of about 10%.     

A secure and robust group key distribution and authentication protocol with efficient rekey mechanism for dynamic access control in secure group communications

In today's Internet era, group communications have become more and more essential for many emerging applications. Given the openness of today's networks, efficient and secure distribution of common key is an essential issue for secure communications in the group. To maintain confidentiality during communication in the group, all authorized members require a common key called the group key in advance. This paper proposes a group key distribution and authentication protocol for dynamic access control in secure group communication using Chinese remainder theorem (CRT), which is highly secure and computationally efficient. The proposed protocol (1) has drastically reduced the computation complexity of group controller ( GC ) and members, (2) has provided intense security by means of an additional secret parameter used by GC and members, (3) has minimized storage and communication overheads, (4) has been decentralized for higher scalability so that it can efficiently handle large‐scale changes in the group membership, and (5) is suitable for many practical applications due to intense security along with low computation and storage overheads. Detailed security analysis proves that our protocol can guarantee the privacy and security requirements of group communications. Moreover, performance analysis also verifies the efficiency and effectiveness of the proposed protocol. The proposed protocol has been experimented on star topology‐based key distribution system and observed that the protocol significantly reduces the computation cost and minimizes the communication and storage overheads.     

Optical properties of CdS<Subscript>0.2</Subscript>Se<Subscript>0.8</Subscript>:V

We report here a comparison between two methods for calculating the index of refraction of the CdS_xSe_1−x alloy system and a calculation of the phase-matching angles for second harmonic generation for this system. Analytical expressions for the index and the birefringence of all x values are presented. The low-temperature photoluminescence spectrum has been measured and reveals a native defect at 1.45 eV and a peak at 1.8 eV caused by the vanadium dopant, as well as an exciton peak at 2.24 eV. The transmission spectrum displays three peaks due to the vanadium dopant at 0.979 eV, 1.087 eV, and 1.181 eV. The birefringence has been measured for x = 0.2 from 1 μm to 14 μm and varies from 0.0185 to 0.0125.     

Poisson shock models leading to new classes of non-monotonic aging life distributions

Suppose a device is subjected to a sequence of shocks occurring randomly in time according to a homogeneous Poisson process. In this paper we introduce a class of non-monotonic aging distributions, the so-called New Worse then Better than Used in Failure Rate (NWBUFR) and New Worse then Better than Average Failure Rate (NWBAFR). It is shown under appropriate conditions on the probability of surviving a given number of shocks that the non-monotonic aging classes NWBUFR and NWBAFR arise from suitable Poisson shock models.     

CSRR Loaded Tunable L-Strip Fed Circular Microstrip Antenna

A tunable L-strip fed circular microstrip antenna on thick substrate with CSRR in the ground plane has been analysed and investigated. The antenna is analysed using cavity model and circuit theoretic approach for initial design and then simulated on IE3D simulation software. The antenna is made tunable with PIN diode which makes it to work in different configurations. Two diodes were used to implement a double annular slot, one annular slot and one split slot and CSRR in the ground plane. While other configurations of diodes provide bandwidth and radiation pattern diversity, CSRR provides size reduction of upto 13.31 % along with high gain directivity and radiation efficiency. A maximum gain of 8 dBi, directivity 8.3 dBi has been achieved in the respective band of operations. The antenna exhibits wideband along with multiband characteristic.     

Analytical one-dimensional current-voltage model for FD SOI MOSFETs including the effect of substrate depletion

In this paper, we present an analytical one-dimensional current-voltage model for silicon-on-insulator (SOI) MOSFETs under full depletion (FD). Our model has been developed from the first principles, and it not only includes the effects of source-drain series resistances, self-heating, and parasitic BJT, which are essential to FD SOI device modeling, but also includes another important effect of substrate depletion, for the first time in the literature, which is of vital significance for FD SOI devices having small film thickness and low substrate doping. The results of the drain current obtained from our model show a much better match with the experimental data, with the maximum error being only 9.41%, which is reasonably lower than the maximum error of 15.04% produced by the model of Yu et al., and marginally better than the error of 11.5% of the model of Hu and Jang. It must be noted that, though the improvements achieved in terms of accuracy are not that significant, yet unlike other models, ours is based on a simplified one-dimensional analytical approach, which is absolutely free from iterations, and hence, there is a huge improvement in terms of computational efficiency, which establishes its practical significance.