Photobiological Production of Hydrogen from Spirulina for Fueling Fuel Cells

Abstract

Natural resources of the world are shrinking day by day with ever increasing population and man's growing need for commercialization of petroleum, natural gas, coal, etc. Therefore, there is a need for finding an alternative fuel that could replace these conventional fuels. Hydrogen seems to be an ideal candidate, since hydrogen is a cleaner source of energy. Fuel cell is a good device that converts hydrogen directly into electrical energy efficiently. However, availability of hydrogen is a problem. There are many conventional methods for producing hydrogen, like thermochemical process, catalytic reforming of hydrocarbons, and electrolysis of water, but these methods are not economical and are mostly non-renewable. Biological means of producing hydrogen offers a renewable source of hydrogen production. Cyanobacteria can split water into hydrogen. Anabaena sp. is found to produce more hydrogen than other species of cyanobacteria; however, if this has to be cultured only for hydrogen production, it may not be commercially viable. Spirulina sp. has a good food value and can produce hydrogen as a byproduct. In order to reduce the cost of the fuel cell, the platinum anode may be replaced by a carbon electrode impregnated with suitable inexpensive metal that may have good catalytic activity such as Co-Al oxide spinel and nickel. Studies towards the photobiological production of hydrogen were undertaken. Hydrogen based fuel cell was assembled and fabricated and these studies are being reported.     

Investigations into salt wedge dynamics at a bar blocked estuary using front tracking approach

The interfacial flow simulations using a robust interface-tracking method are presented. The method is based on one fluid formulation, where a single set of governing equations for the whole computational domain with variable material properties is solved. Interfacial terms, at the boundary separating the phases, are accounted for by adding the appropriate sources as δ functions. The representation of the moving interface and its dynamic restructuring, as well as the transfer of information between the moving front and the fixed grid, is discussed. This method has been applied to density stratified flows, and interfacial movements are then presented. An experimental study on salt wedge movement, conducted in the University of Dundee, has been simulated using the above algorithm. The numerical results are compared with the experimental results and those of a semi-empirical model developed earlier by the authors.     

A Novel Method Based on Capillary Suction Time (CST) for Assessment of Dispersion Characteristics of Suspensions

This paper presents the applicability of a simple and novel technique based on capillary suction time (CST) to characterize the dispersibility of suspension. The method is simple, rapid, and requires little experience. It has been shown to be extremely useful for comparing the dispersibility during preparation of a stable suspension of ceramic powder with high solids loading. The method has also been found to be suitable for obtaining homogeneous suspensions of maximum stability. The dispersibility of particles in any suspension has been assessed with respect to the condition at point of zero charge (pH_pzc). A quantitative measure of the dispersibility has been proposed in term of a dispersion ratio (DR). According to this proposition, the suspension is in a state of dispersion when the value of DR is more than unity, whereas it is in a flocculated state when the value of DR is less than unity.     

Multiple Water Use Protocols in Integrated Farming System for Enhancing Productivity

Agriculture is the largest consumer of water in world. Due to demand of water for industrial and drinking purposes, the share of available water resources in agriculture sector is reducing substantially in near future. However, the food, fodder, fuel, and fibre production for satisfying the demands of enhanced population requires more water. In this scenario, increasing water productivity through diversified farming system has been identified as one of the viable options. Diversified farming, otherwise also called integrated farming system (IFS), represents integration of various enterprises such as cropping systems, horticulture, animal husbandry, fishery, agro-forestry, apiary etc. for optimal utilization of farm resources besides water. Integrated farming, a judicious mix of cropping systems suited to given agro-climatic conditions and socio-economic status of the farmers, shall be able to generate additional employment and income for the small and marginal farmers under both rain-fed and irrigated environment. Although, IFS was mainly initiated in Asian agriculture, it is being introduced in almost all the countries of world. Such a system results in more rationale use of water with judicious distribution among different users. In this paper, different aspects of multiple uses of water for higher productivity and future strategies for enhancing water productivity are discussed.     

Visual–Motor Coordination Using a Quantum Clustering Based Neural Control Scheme

Visual–Motor Coordination is a problem considered analogous to the hand-eye coordination in biological systems. In this work we propose a novel approach to this problem using Quantum Clustering and an extended Kohonen's Self-Organizing Feature Map (K-SOFM). This facilities the use of the method in varying workspaces by considering the joint angles of the robot arm. Unlike previous work, where a fixed topology for the input space is considered, the proposed approach determines a topology as the workspace varies. Quantum Clustering is a method which constructs a scale-space probability function and uses the Schroedinger equation and its lowest eigenstate to obtain a potential whose minimum gives the cluster centers. It transforms the input space into a Hilbert space, where it searches for its minimum. The motivation of this work is to identify the implicit relationship existing between the end-effector positions and the joint angles through Quantum Clustering and Neural Network methods to fine-tune the system to correctly identify the mapping.     

Preparation and characterization of Simvastatin solid dispersion using skimmed milk

Simvastatin has low aqueous solubility resulting in low oral bioavailability (5%) and thus presents a challenge in formulating a suitable dosage form. To improve the aqueous solubility, a solid dispersion formulation of Simvastatin was prepared by lyophilization utilizing skimmed milk as a carrier. Six different formulations were prepared with varying ratios of drug and carrier and the corresponding physical mixtures were also prepared. The improvement of amorphous state through solid dispersion was confirmed by differential scanning calorimetry and X-ray diffraction studies. The optimum drug-to-carrier ratio of 1:9 enhanced solubility nearly 30-fold as compared to pure drug. In-vitro drug release studies exhibited a cumulative release of 86.69% as compared to 25.19% for the pure drug. Additionally, scanning electron microscopy studies suggested the conversion of crystalline Simvastatin to an amorphous form. In a Triton-induced hyperlipidemia model, a 3-fold increase in the lipid lowering potential was obtained with the reformulated drug as compared to pure drug. These results suggest that solid dispersion of Simvastatin using skimmed milk as carrier is a promising approach for oral delivery of Simvastatin.     

Study of Structural Modification and Fluctuation Induced Electrical Conductivity in \text {YBa}_{2}\text {Cu}_{3}\text {O}_{7-y}+x \text {BaSnO}_{3} Superconductor Composite

A series of \((1-x) \text {YBa}_{2}\text {Cu}_{3}\text {O}_{7-y} + x \text {BaSnO}_{3 }(x = 0.0, 0.1, 0.3, 0.5, 1.0, 2.5, 5.0\,\text {wt}{\%})\) samples were prepared using the solid-state reaction method. XRD graphs confirm the orthorhombic structure in pristine as well as in composite samples. Raman spectra show the presence of all the vibration modes in pure as well as in the composite samples. In addition, some defect-induced modes have also appeared in the higher weight % BSO-added sample, and no loss of apical oxygen O(4) at 500 cm \(^{-1}\) occurs due to BaSnO \(_{3}\) (BSO) addition. Microstructural analysis reveals the unchanged grain size with the incorporation of dielectric BSO particles in the YBCO matrix. Superconducting transition temperature determined from standard four-probe method decreases with the increase of BSO wt%. Excess conductivity fluctuation analysis using Aslamazov–Larkin model fitting reveals transition of two dominant regions (2D and 3D) above \(T_\mathrm{c}\) . 2D to 3D crossover temperature i.e. Lawrence–Doniach temperature that demarcates dimensional nature of fluctuation inside the grains is influenced by BSO incorporation in YBCO matrix.     

Electrophoretic deposition of alumina on stainless steel from non-aqueous suspension

Electrophoretic deposition of alumina on stainless steel has been investigated. The influence of different organic media and deposition parameters such as solid concentration, applied voltage and time of deposition on deposit yield has been evaluated. Maximum deposit yield was obtained for solvent media that imparts highest magnitude of surface charge on alumina in suspension. The deposit yield increased linearly with concentration of alumina powder in suspension, and applied voltage following Hamakers law. A similar linearity in yield was observed at short deposition times, but a deviation in linearity was observed at higher time of deposition, which is attributed to the shielding effect of the deposited layers and accumulation of ions at the electrode, and depletion of powder in the suspension with progress in deposition.     

Structural and electrical properties of Na2Pb2Eu2W2Ti4X4O30 (X = Nb, Ta) ferroelectric ceramics

A new group of tungsten bronze family Na₂Pb₂Eu₂W₂Ti₄X₄O₃₀ (X = Nb, Ta) having all the valence elements (I-VI) were prepared by a high-temperature solid-state reaction technique. The formations of the compounds were confirmed by X-ray diffraction technique with an orthorhombic structure. Surface morphology of the compounds was studied by scanning electron microscope (SEM). Studies of dielectric properties (?_r and tan δ) of the above compounds at different frequencies in a wide temperature range (300-700 K) with an impedance analyzer exhibit a ferroelectric phase transition at 580 and 394 K for Na₂Pb₂Eu₂W₂Ti₄Nb₄O₃₀ and Na₂Pb₂Eu₂W₂Ti₄Ta₄O₃₀, respectively. Ferroelectric properties of these compounds were confirmed with polarization (hysteresis) study.