Nitrate removal efficiency of bacterial consortium (Pseudomonas sp. KW1 and Bacillus sp. YW4) in synthetic nitrate-rich water

The efficiency of bacterial isolates to reduce nitrate from synthetic nitrate-rich water was tested using a batch scale process. Two efficient nitrate reducing bacterial species were isolated from water samples collected from Kodaikanal and Yercaud lakes. Bacterial analysis of the samples revealed the presence of nitrate reducing bacteria belonging to the genera Pseudomonas, Bacillus, Micrococcus and Alcaligenes. Among the isolates, the consortium of Pseudomonas sp. KW1 and Bacillus sp. YW4 was found to be efficient in nitrate reduction. Influences of various carbon sources, incubation temperature and pH on nitrate reduction from synthetic wastewater were also studied. The results showed a rapid and efficient process of nitrate removal (99.4%) from synthetic wastewater supplemented with starch (1%), inoculated by bacterial consortium (Pseudomonas sp. KW1 and Bacillus sp. YW4) at incubation temperature of 30 degrees C at pH 7. This observation has led to the conclusion that the bacterial consortium was responsible for nitrate removal from synthetic nitrate-rich wastewater.     

Determination of critical network interactions: an augmented Boolean pseudo-dynamics approach

Network theory has established that highly connected nodes in regulatory networks (hubs) show a strong correlation with criticality in network function. Although topological analysis is fully capable of identifying network hubs, it does not provide an objective method for ranking the importance of a particular node by relating its contribution to the overall network response. Towards this end, the authors have developed an augmented Boolean pseudo-dynamics approach to a priori determine the critical network interactions in biological interaction networks. The approach utilises network topology and dynamic state information to determine the set of active pathways. The active pathways are used in conjunction with the key cellular properties of efficiency and robustness, to rank the network interactions based on their importance in the sustenance of network function. To demonstrate the utility of the approach, the authors consider the well characterised guard cell signalling network in plant cells. An integrated analysis of the network revealed the critical mechanisms resulting in stomata closure in the presence and absence of abscisic acid, in excellent agreement with published results.     

Assessment of convective heat transfer coefficient and mass of water evaporated from a single-slope passive solar still by different thermal models: an experimental validation

In this paper, an effort has been made to evaluate the convective heat transfer coefficient and mass of water evaporated from a single-slope passive solar still for different water depths (0.01, 0.015, 0.02 and 0.025?m) by various thermal models, namely Dunkle’s model, Chen et al.’s model, Clark’s model, Adhikari et al.’s model, Kumar and Tiwari’s model, Zheng Hongfei et al.’s model and Tsilingiris’s model. These models were studied and compared with our experimental work. Also, the energy and exergy efficiency were calculated and the percentage deviation between experimental and theoretical prediction is also listed out. The experimental validation of energy and exergy efficiency of single slope passive solar still using different thermal models was carried out at Chennai, Tamil Nadu, India. By comparing the theoretical values of the hourly yield with the experimental data it was found that Dunkle’s, Chen et al.’s and Tsilingiris’s models gave better conformity between the forecasted and experimental results. Kumar and Tiwari’s model yield is very high, whereas Clark’s model, Adhikari et al.’s model and Zheng Hongfei et al.’s model predict lower values as compared with our experimental results.     

REquirements TRacing On target (RETRO): improving software maintenance through traceability recovery

A number of important tasks in software maintenance require an up-to-date requirements traceability matrix (RTM): change impact analysis, determination of test cases to execute for regression testing, etc. The generation and maintenance of RTMs are tedious and error-prone, and they are hence often not done. In this paper, we present REquirements TRacing On-target (RETRO), a special- purpose requirements tracing tool. We discuss how RETRO automates the generation of RTMs and present the results of a study comparing manual RTM generation to RTM generation using RETRO. The study showed that RETRO found significantly more correct links than manual tracing and took only one third of the time to do so. Work performed while A. Dekhtyar was on the faculty at the University of Kentucky.     

Application of colloidal gas aphrons for pollution remediation

Colloidal gas aphrons (CGAs), first described by Felix Sebba in his book Foams and Biliquid Foams—Aphrons in 1987, consist of a system of spherical microbubbles with diameters mostly above 25 µm and classified as kugelschaums (ball foam). They possess some colloidal properties and can be pumped at uniform rate through pipes and channels, much like liquids. Also, they have high stability due to very small size and thick surfactant shells. Research work published over the past two decades indicate effective applications of CGAs for clarification of particles and microorganisms, protein separation, gas and nutrient transfer and pollutant separation from water and soil matrices. In this review paper, the techniques for generating CGAs and their application to pollution abatement are discussed. Some mineral separation processes by CGA flotation have also been reviewed because of their relevance to contaminant removal processes. The CGAs were found to function on the principles of bubble entrained floc flotation, electrostatic and ionic interaction, diffusion of entrapped gas and hydrophobicity of the pollutant particles. Two tables have also been provided to present a comparative overview of the generation technologies and the effectiveness of pollution remediation techniques. Copyright © 2012 Society of Chemical Industry     

Gallium antimonide infrared solar cells with improved efficiency and manufacturability

Mechanically-stacked gallium arsenide (GaAs) and gallium antimonide (GaSb) concentrator solar cells have achieved the highest photovoltaic receiver efficiency to date. This paper describes a new process for GaSb infrared cells that has produced cells with higher efficiency, manufacturability and yield. Cells with efficiency of 6.6% under a GaAs filter have been demonstrated at 50X AM0. These cells were exposed to 1 MeV protons, and were shown to have higher end-of-life efficiencies than the previous cells. V-grooving the front surface resulted in s slightly higher radiation resistance.     

Multicarrier spread spectrum watermarking for secure error concealment in fading channel

This paper proposes a novel multicarrier spread spectrum (SS) watermarking scheme for the application of image error concealment using multicarrier-code division multiple access (MC-CDMA) with binary phase shift keying (BPSK) transmission in Rayleigh fading channel. The goal is achieved by embedding important information (image digest) which is extracted from the original image itself, and is used to introduce sufficient redundancy in the transmitted image. Half-toning technique is applied to obtain image digest from its low-resolution version. At the decoder side, data demodulation as well as watermark decoding are done using minimum mean square error combining (MMSEC) strategy. The extracted image digest is used to correct the damaged regions. The integration of SS watermarking with the existing SS modulation not only simplifies the design but also offers significant performance improvement for error concealment in fading channel. Authorized users having the knowledge of code patterns for SS watermarking can only perform the error concealment operation and the method is secured. Experimental results duly support the effectiveness of the proposed scheme.     

Studies on chemical bath deposited cadmium sulphide films by buffer solution technique

Cadmium sulphide films were grown by a chemical bath technique using cadmium acetate and cadmium chloride as the Cd ion source and thiourea as the sulphur source. The solution growth process was carried out with and without buffer solutions containing ammonium acetate and ammonium chloride onto glass substrates. Various properties of the films such as surface morphology, crystallinity, composition, optical properties and dark resistivities were compared for both the above techniques.