Electrophoretic deposition of CuO particulate thick film for ethanol sensing

Journal of Materials Science: Materials in Electronics - Detection of volatile organic compounds is of utmost importance in numerous applications such as medical diagnosis, air quality monitoring,...     

Automated Controller Placement for Software-Defined Networks to Resist DDoS Attacks

In software-defined networks (SDNs), controller placement is a critical factor in the design and planning for the future Internet of Things (IoT), telecommunication, and satellite communication systems. Existing research has concentrated largely on factors such as reliability, latency, controller capacity, propagation delay, and energy consumption. However, SDNs are vulnerable to distributed denial of service (DDoS) attacks that interfere with legitimate use of the network. The ever-increasing frequency of DDoS attacks has made it necessary to consider them in network design, especially in critical applications such as military, health care, and financial services networks requiring high availability. We propose a mathematical model for planning the deployment of SDN smart backup controllers (SBCs) to preserve service in the presence of DDoS attacks. Given a number of input parameters, our model has two distinct capabilities. First, it determines the optimal number of primary controllers to place at specific locations or nodes under normal operating conditions. Second, it recommends an optimal number of smart backup controllers for use with different levels of DDoS attacks. The goal of the model is to improve resistance to DDoS attacks while optimizing the overall cost based on the parameters. Our simulated results demonstrate that the model is useful in planning for SDN reliability in the presence of DDoS attacks while managing the overall cost.     

Simultaneous Identification of Different Domains of Calpain from Blood and Turkey Meat Samples Using Casein Zymography

The aim of this study was to develop a simple method for simultaneous identification of two different domains of calpains (μ- and m-calpains) in blood and turkey meat samples. The method is based on Tris-based extraction techniques followed by casein zymography detection. The extracts were purified by dialysis, and target compounds were separated on Diethylaminoethyl (DEAE)-Sephacel anion-exchange chromatography. Results indicated that a buffer pH of 6.7 produced optimum extraction efficiency. The separation of calpastatin, μ- and m-calpains on column chromatography was carried out using stepwise elution profiles of 100, 200, and 400 mM NaCl solutions, respectively. Casein zymography study clearly demonstrated the presence of μ- and m-calpains in the crude extracts of breast and blood samples; however, μ-calpain was absent in the thigh sample. Similarly, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis identified both the calpains from muscle and blood samples, but presence of calpastatin was observed in both the breast and thigh muscle samples only. The activity analysis of purified fractions indicated that both the μ- and m-calpain concentrations were differed significantly (P?<?0.05) amongst breast, thigh and blood samples. Collectively, it was concluded that Tris buffer (pH 6.7) and DEAE-Sephacel column for extraction and separation of μ- and m-calpains and casein zymography and SDS-PAGE detection methods were most suitable for accurate identification of calpains and calpastatin from blood and turkey meat samples.     

Analysis of dispersion coefficient of bubble motion and velocity characteristic factor in down and upflow bubble column reactor

Dispersion coefficient of bubble motion based on velocity distribution theory has been analyzed in up and downward gas-liquid two-phase contactor. The intensity of dispersion of phase depends on motion of the dispersed phase and the characteristics of velocity distribution. In this paper the effects of operating and geometric variables on the dispersion coefficient of bubble motion and the characteristic factor of velocity distribution have been analyzed within the range of column diameter 0.10-2.5 m, superficial liquid velocity, 0.04-0.21 m/s and superficial gas velocity 0.41-3.16 mm/s. From the different developed model of longitudinal dispersion coefficient of liquid, comparison of dispersion coefficient of bubble motion and characteristic feature of velocity distribution in down and upflow two-phase contactor has been reported. Also the functionalities of dispersion coefficient of bubble motion and velocity characteristic factor have been developed with operating variables. The condition for dispersion based on velocity pattern has also been discussed in the present work. The present analysis on the dispersion coefficient of bubble motion and velocity distribution factor associated with the knowledge of the liquid phase dispersion in two-phase contactor can give insight into a further understanding and modeling of multiphase reactor in industrial applications.     

Biodegradation of pyridine by the new bacterial isolates S. putrefaciens and B. sphaericus

In this study, two bacterial strains capable of utilizing pyridine as a sole carbon source were isolated from biofilters. Based on the biochemical test, the organisms were identified as Shewanella putrefaciens and Bacillus sphaericus. In liquid cultures, S. putrefaciens and B. sphaericus degraded pyridine quite effectively up to 500 mg L(-1). S. putrefaciens degrades 500 mg L(-1) of pyridine completely within 140 h, whereas the B. sphaericus degrades 500 mg L(-1) of pyridine only nearly 75% and takes a longer duration of 150 h. S. putrefaciens used pyridine as sole carbon and energy source better than B. sphaericus. Monod's and Haldane's inhibitory growth models were used to obtain maximum specific growth rate (micro(max)), half saturation (K(s)) and substrate inhibition (K(i)) constant for pyridine by using S. putrefaciens and B. sphaericus. The high value of K(i) for S. putrefaciens than B. sphaericus indicates that the inhibition effect can be observed only in a high concentration range. The S. putrefaciens degrades pyridine with a faster rate than B. sphaericus. S. putrefaciens can be used effectively for the treatment of pyridine bearing wastewater and as an inoculum in a biofilter treating pyridine-laden gas.     

Treatment of arsenic contaminated water in a laboratory scale up-flow bio-column reactor

The present paper describes the observations on the treatment of arsenic contaminated synthetic industrial effluent in a bio-column reactor. Ralstonia eutropha MTCC 2487 has been immobilized on the granular activated carbon (GAC) bed in the column reactor. The synthetic water sample containing As(T) (As(III):As(V)=1:1), Fe, Mn, Cu and Zn at the initial concentrations of 25, 10, 2, 5, 10 ppm, respectively, was used. Concentrations of all the elements have been found to be reduced below their permissible limits in the treated water. The significant effect of empty bed contact time (EBCT) and bed height on the arsenic removal was observed in the initial stage. However, after some time of operation (approximately 3-4 days) no such effect was observed. Removal of As(III) and As(V) was almost similar after approximately 2 days of operation. However, at the initial stage As(V) removal was slightly more than that of As(III). In absence of washing, after approximately 4-5 days of operation, the bio-column reactor was observed to act as a GAC column reactor based on physico-chemical adsorption. Like arsenic, the percent removals of Fe, Mn, Cu and Zn also attained minimum after approximately 1 day and increased significantly to the optimum value within 3-4 days of operation. Dissolved oxygen (DO) has been found to decrease along with the increasing bed height from the bottom. The pH of the solution in the reactor has increased slightly and oxidation-reduction potential (ORP) has decreased with the time of operation.     

Design of a biomolecular device that executes process algebra

Process algebras are widely used for defining the formal semantics of concurrent communicating processes. This paper considers stochastic π-calculus which is a particularly expressive kind of process algebra providing a specification of probabilities of process behavior such as stochastic delays, communication and branching, as well as rates of execution. In this paper, we implement stochastic π-calculus at the molecular scale, providing a design for a DNA-based biomolecular device that executes the stochastic π-calculus. Designing this device is challenging due to the requirement that a specific pair of processes must be able to communicate repeatedly; this appears to rule out the use of many of the usual classes of DNA computation (e.g., tiling self-assembly or hybridization chain reactions) that allow computational rule molecules to float freely in solution within a test tube. Our design of the molecular stochastic π-calculus system makes use of a modified form of Whiplash-PCR (WPCR) machines. In our machine which we call π-WPCR machine, we connect (via a tethering DNA nanostructure) a number of DNA strands, each of which corresponds to a π-WPCR machines. This collection of π-WPCR machines is used to execute distinct concurrent processes, each with its own distinct program. To implement process communication protocols, our modifications to the original design of WPCR machines include the incorporation of additional secondary structure in the single strand (stem-loop) as well as multiple-temperature thermal cycling. The enforced locality of the collection of π-WPCR machines insures that the same pair (or any subset of the entire collection) of processes be able to repeatedly communicate with each other. Additionally, our design of the devices include implementation of sequential execution of multiple process and limited process branching through use of restriction enzymes.     

Investigation on the Dielectric and Polarization Behavior of Sol-Gel Derived Erbium Doped Pb(Zr 0.53 Ti 0.47 )O 3 Thin Films

We have studied the effect of Er 3+ doping on the dielectric and polarization hysteresis behavior of sol-gel derived Pb 1.05 (Zr 0.53 Ti 0.47 )O 3 thin films. Up to 1 at% Er doping, the dielectric constant of undoped PZT increases from 1245 to 1477 (measured at 50 kHz, 500 mV oscillation voltage), whereas the remnant polarization increases from 30 to 41 w C/cm 2 . Under the subswitching external field, the dielectric permittivities follow the Rayleigh law. The Rayleigh coefficient ( f ) was considered as a measure of the ease of domain wall motion. Up to 1 at% Er doping, the increase of f indicates minimal defect-domain wall interaction due to lower defect concentration. Under the switching field, the irreversible part of the switchable polarization was estimated from the C-V and hysteresis measurements. At the saturation field it was observed that up to 1 at% Er doping the irreversible component at switchable polarization increases and reversible component remains low. The improvements of dielectric and ferroelectric properties for up to 1 at% Er doping have been correlated to the relative site occupancy of Er 3+ as a function of Er content in PZT host lattice.     

Diffuse Phase Transition Characteristics and Relaxor Behavior of Lanthanum Doped Lead Titanate Thin Films

Room temperature micro-Raman scattering, P-E hysteresis and temperature dependent dielectric measurements were carried out on sol-gel derived ferroelectric Pb 1 m x La x TiO 3 (PLT x = 0.0 to 0.30) thin films. micro-Raman results indicate that the crystal structure of the PLT films was strongly influenced by the La contents. The dielectric properties of PLT thin films were studied in the temperature range 80-700 K and frequencies (1 kHz - 1MHz). Results indicate that PLT thin films undergo normal-to-relaxor ferroelectric transformation with 30 at% La content in PLT films. The observed behavior is evaluated in terms of diffuseness and Vogel-Fulcher relationship, which is typical for relaxor ferroelectrics.     

Lattice Boltzmann method for population balance equations with simultaneous growth,nucleation, aggregation and breakage

Lattice Boltzmann method (LBM) is developed for solution of one-dimensional population balance equations (PBEs) with simultaneous growth, nucleation, aggregation and breakage. Aggregation and breakage, which act as source terms in PBEs, are included as force terms in LBM formulation. The force terms representing aggregation and breakage are evaluated by fixed pivot (FP) method. Multiscale analysis is used to derive the kinetic equations associated with LBM, whose long-time large-scale solution provides the solution of the PBE. A coordinate transformation is proposed, which allows the use of non-uniform grid for LBM to obtain accurate solution of PBE with moderate number of grid points. The performance of the proposed LBM-FP method is compared with finite volume (FV) and method of characteristics (MOC) combined with FP (MOC-FP) methods. Using benchmark examples, the proposed LBM-FP method is shown to be useful for solving PBEs due to its computational efficiency and ability to handle a wide range of problems.