Performance of a multiple-wick solar still with condenser

In a conventional still, because the water condenses underneath a glass cover, its temperature becomes quite high. During the period of maximum sunshine, the glass temperature is higher than the dew point of the air-vapour mixture inside the still. Thus the yields of these kinds of stills are low. In this communication we have investigated experimentally the performance of a still with a condenser. Most of the condensation now takes place in the condenser, consequently the glass temperature remains low causing less heat loss to the ambient environment. The yield of the condenser-type still is higher than that of the non-condenser-type still.     

Radiative capture cross-sections of isotopes of Gd,Sm and V between 1 and 3 MeV

Fast-neutron radiative capture cross-sections have been measured relative to the ¹²⁷I(n, γ)¹²⁸I reaction cross-section using the comparative activation technique for ¹⁶⁰Gd, ¹⁵⁴Sm and ⁵¹V (using enriched isotopes and Specpure samples) at five different neutron energies between 1 and 3 MeV. The cross-section for ¹⁶⁰Gd is reported for the first time in the above energy region. Experimental values are compared with the statistical-model calculations.     

Solubilization of phospholipid vesicular structures into mixed micelles of zwitterionic surfactants

Interactions between the binary combination of dimethyltetradecylammoniopropanesulfonate (TPS) and l-α-phosphatidylcholine (PC), 1,2-didecanoyl-sn-glycero-3-phosphocholine, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine in the aqueous bulk phase were evaluated with the help of pyrene fluorescence (l ₁/l ₃) measurements by studying the aggregation processes of TPS in pure water and in the presence of 7–36 μM of fixed concentrations of each lipid. The fluorescence measurements showed that TPS monomers undergo two kinds of aggregation process, which were identified by the three breaks. The first break, C₁, and the second, C₂, indicated the onset and completion of bilayer solubilization, respectively, on the incorporation of TPS monomers into the bilayer assemblies, which led to bilayer solubilization in the form of mixed micelles. This process was not clearly visible in the presence of PC, whereas some kinds of structure transitions were observed upon the incorporation of surfactant monomers. The partition coefficient (K), which defines the degree of partitioning of surfactant monomers into the bilayers with respect to the aqueous medium, was evaluated. A high K value of TPS-lipid aggregates indicated stronger interactions between surfactant and bilayer assemblies of lipid. The K values determined for the three phospholipids are close to each other, which indicates that K values do not depend on the hydrocarbon chain length of the phospholipid but of the surfactant used.     

Solution growth of variable gap Pb1−xHgxS films for infrared detectors

A solution growth technique has been developed for preparation of variable gap Pb_1?xHg_xS alloy films for infrared detectors. Using appropriate growth conditions, PbS alloys with both α-HgS or β-HgS phases can be formed. Thus, the optical gap of the alloy films can be varied from 0.1 to 2 eV.     

Studies on the kinetics of photo-initiated radical polymerisation of modified epoxy resin

The diglycidyl ether of bisphenol-A (DGEBPA) was modified by acrylic acid. The reaction between the active epoxy groups of DGEBPA and the carboxylic group of acrylic acid was catalysed by triphenyl phosphine to prepare di(vinyl-2-hydroxypropanoate) ether of bisphenol-A (DEBA). The DEBA so formed was co-polymerised with 2-ethylhexylacrylate using benzophenone as the photo-initiator to yield a flexible polymer. The kinetics of the photo-initiated radical polymerisation was studied by a new technique called differential photo-calorimetery and the results thus obtained were analysed to determine the Arrhenius activation energy and pre-exponential factor.     

Coupled thermal structural analysis of LWR vessel creep failure experiments

Considering the hypothetical core melt down scenario for a light water reactor (LWR) the failure mode of the reactor pressure vessel (RPV) has to be investigated to determine the loadings on the containment. The failure of reactor vessel retention (FOREVER)-experiments, currently underway, are simulating the thermal and pressure loadings on the lower head for a melt pool with internal heat sources. Due to the multi-axial creep deformation of the vessel with a non-uniform temperature field these experiments are an excellent source of data for validation of numerical creep models. Therefore, a finite element (FE) model has been developed based on a commercial multi-purpose code. Using the computational fluid dynamics (CFD) module the temperature field within the vessel wall is evaluated. The transient structural mechanical calculations are performed using a new numerical approach, which avoids the use of a single creep law employing constants derived from the data for a limited stress and temperature range. Instead of this a three-dimensional array is developed where the creep strain rate is evaluated according to the values of the actual total strain, temperature and equivalent stress. Care has to be exercised performing post-test calculations particularly in the comparisons of the measured data and the numerical results. Considering the experiment FOREVER-C2, for example, the recorded creep process appears to be tertiary, if a constant temperature field is assumed. But, small temperature increase during the creep deformation stage could also explain the observed creep behavior. Such considerations provide insight and better predictive capability for the vessel creep behavior during prototypic severe accident scenarios.     

Reliability evaluation and selection of rolling element bearings

A procedure based on graph theory and matrix approach has been developed for the reliability evaluation and selection of a rolling element bearing for an application. The reliability of the bearing is evaluated considering reliability of its elements and their connections. This is modeled in terms of Reliability Graph of a Rolling Element Bearing. This graph is represented by an equivalent matrix called Rolling Element Bearing Reliability Permanent Matrix to obtain a matrix function-Reliability Permanent Function. This function is the characteristic of reliability of the rolling element bearing for the application. Reliability Index (R_I) of the bearing is also defined. It is a numerical measure of the bearing reliability and is obtained by substituting reliability value of the bearing elements and their connections in the matrix function. The paper also suggests how to assess these reliability values to obtain the index. The proposed procedure is useful for designers and practicing engineers for selection of an optimum bearing for a given application. The methodology is illustrated by means of an example.     

Energy harvesting from sediment microbial fuel cell to supply uninterruptible regulated power for small devices

Sediment microbial fuel cell (SMFC) is a bio‐electrochemical device that generates direct current by microbes present in the soil. The main drawback of SMFC is the low voltage and fluctuations. Therefore, a suitable scheme is required to obtain sufficient voltage with insignificant fluctuation. This paper proposes an energy harvester power management system (PMS) to get rid of low voltage and fluctuation problem of SMFC. The proposed PMS is composed of a dc‐dc boost converter, switches, and super capacitors. The boost converter (using LTC3108 IC) successfully steps up the voltage up to 2.658 V and provides it to the load for 1.5 minutes. Four SMFCs connected with four individual super capacitors and a single boost converter has been used to implement this scheme. In this strategy, the charging and discharging time of the SMFCs are controlled in such a way that the continuous power will be supplied to the load with the optimum number of SMFCs. This scheme is tested on an experimental setup. It is found that the energy harvester PMS supplies a continuous voltage of 2.658 V with the efficiency of 85.46%, which is sufficient to power for small devices such as remote environment sensors, temperature sensors, LED lighting, and submersible ultrasonic receiver.     

Development and Characterization of Electropsun Poly(propylene carbonate) Ultrathin Fibers as Tissue Engineering Scaffolds

Electrospinning is a desired method to produce ultrathin fibers for tissue engineering. In order to mimic the nanofibrous structure of the extracellular matrix (ECM) poly(propylene carbonate) ultrathin fibers were electrospun using N,N‐dimethyl acetamide as solvent. Cationic surfactant, cetyl trimethyl ammonium bromide, was found to aid in the formation of beadless fibers of poly(propylene carbonate). Electrospinning parameters viz. concentration of polymer and that of the surfactant used as an additive, flow rate, electrostatic field, and effect of inner diameter of the needle were investigated and optimized. Scanning electron microscopy showed porous scaffold and fibers of diameter ranging from nano‐ to submicron range. FTIR spectroscopy and thermal analysis of the obtained fibers ensured the complete evaporation of solvent and optimal thermal stability of fibers for tissue engineering applications. The prepared fibers possess Young's modulus of 10.19 and 26.39 GPa with the tensile strengths of 22.11 and 21.29 MPa under dry and wet conditions, respectively. The fiber mat was measured to have a porosity of 48% and exhibited competent water retention capacity of 64%. Furthermore the scaffold was found to support the adhesion of mouse NIH 3T3 fibroblasts proving its mettle as a potential scaffold for tissue engineering applications.