Fluorescence correlation spectroscopy: an efficient tool for measuring size, size-distribution and polydispersity of microemulsion droplets in solution

Fluorescence correlation spectroscopy (FCS) is an ideal tool for measuring molecular diffusion and size under extremely dilute conditions. However, the power of FCS has not been utilized to its best to measure diffusion and size parameters of complex chemical systems. Here, we apply FCS to measure the size, and, most importantly, the size distribution and polydispersity of a supramolecular nanostructure (i.e., microemulsion droplets, MEDs) in dilute solution. It is shown how the refractive index mismatch of a solution can be corrected in FCS to obtain accurate size parameters of particles, bypassing the optical matching problem of light scattering techniques that are used often for particle-size measurements. We studied the MEDs of 13 different W(0) values from 2 to 50 prepared in a ternary mixture of water, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), and isooctane, with sulforhodamine-B as a fluorescent marker. We find that, near the optical matching point of MEDs, the dynamic light scattering (DLS) measurements underestimate the droplet sizes while FCS estimates the accurate ones. A Gaussian distribution model (GDM) and a maximum-entropy-based FCS data fitting model (MEMFCS) are used to analyze the fluorescence correlation curves that unfold Gaussian-type size distributions of MEDs in solution. We find the droplet size varies linearly with W(0) up to ~20, but beyond this W(0) value, the size variation deviates from this linearity. To explain nonlinear variation of droplet size for W(0) values beyond ~20, we invoke a model (the coated-droplet model) that incorporates the size polydispersity of the droplets.     

Applying mechanistic models to reliability evaluation of mechanical components – An illustration

The traditional reliability analyses, considers components to be in binary state, either functional or faulty, and does not consider the concept of multi state or intermediate states between these two binary states. However, there are several components, which need to be operated in different states and their failure criterion also depend on these states. Hence, when dealing with these types of components one should use multi state concept. This can be achieved by modeling the components with mechanistic models, which can give a new dimension for reliability analysis for multiple states. The mechanistic model approach is based on the first principles of science and engineering which provides details about the various failure mechanisms and thereby improved understanding of the associated root causes of the failure and driving forces responsible for component failures. In this paper a general methodology for modeling the components with mechanistic models has been explained and is further illustrated with an example component. A case study on feed water system (consisting of control valves and other mechanical components) of a typical nuclear reactor has been presented.     

Performance of a domestic pellet boiler as a function of operational loads: Part-2

Emissions and efficiency of a pellet boiler (40 kW) at nominal load were compared with emissions and efficiency at reduced load, while fired with six biomass pellets. The pellets include reed canary grass (Phalaris arundinacea), pectin waste from citrus shells (Citrus reticulata), sunflower husk (Helianthus annuus), peat, wheat straw (Triticum aestivum) and wood pellets. The measurements of emissions comprised of carbon monoxide (CO), nitrogen oxides (NO_x), sulphur oxides (SO_x) and flue dust mass concentrations (using DINplus and isokinetic sampling techniques). Emissions varied as a function of operational loads, for each type of pellets.The CO emissions were insignificant with reed canary grass (RCG), citrus pectin waste (CPW) and straw pellets at nominal load, however, at reduced load same pellets emitted 1.9, 4.0 and 7.4 times higher CO than wood pellets, respectively. Peat pellets emitted maximum CO at nominal load (4221.1 mgNm⁻³, 12.6 times higher than wood pellets) however; at reduced load CO emission was insignificant. The highest NO_x emissions were reported with CPW, which were 3.4 and 4.6 times higher than wood pellets at nominal load and reduced load, respectively. Dust emissions were highest with sunflower husk and lowest with RCG pellets, at both operational modes. The best performance was reported with wood pellets, followed by RCG and pectin pellets, however, wood pellets combustion emitted 1.7 and 2.0 times higher dust_DINplus than RCG at nominal and reduced loads, respectively. Not only fuel specific combustion optimization but also operational load specific optimization is essential for efficient use of agro-pellets in this type of boilers.     

Association of GSTM1 and GSTT1 polymorphisms with DNA damage in coal-tar workers

DNA damage was evaluated by alkaline comet assay in peripheral blood lymphocytes of 115 coal-tar workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs) and 105 control subjects. The effect of polymorphisms of glutathione S-transferase (GST) genotypes on the DNA damage was assessed. The mean tail moment (TM) value in the coal-tar workers was significantly higher as compared to the control subjects (12.06 ± 0.55 versus 0.44 ± 0.31; P < 0.05). No significant association (P > 0.05) between the GSTT1 and GSTM1 genotypes and the TM values was found, however highest mean rank TM value was reported in GSTM1 null and GSTT1 null genotypes in both control and exposed subjects. Our results suggest that there is increased DNA damage in coal-tar workers due to PAHs exposure. Polymorphisms in GSTM1 and GSTT1 genes do not show significant effect (P > 0.05) on DNA damage.     

Potential of powdered activated mustard cake for decolorising raw sugar

BACKGROUND: Carbon decolorisation has become customary in the food processing industries; however, it is not economical. Extensive research has therefore been directed towards investigating potential substitutes for commercial activated carbons which might have the advantage of offering an effective, lower‐cost replacement for existing bone char or coal‐based granular activated carbon (GAC). RESULTS: The physical (bulk density and hardness), chemical (pH and mineral content) and adsorption characteristics (iodine test, molasses test and raw sugar decolorisation efficiency) of powdered activated mustard cake (PAMC) made from de‐oiled mustard cake were determined and compared to commercial adsorbents. Although the colour removal efficiency of the PAMC is lower than that of commercial materials, it is cost effective and eco‐friendly compared to the existing decolorisation/refining processes. To reduce the load on GAC/activated carbon/charcoal, PAMC could be used on an industrial scale. A decolorisation mechanism has been postulated on the basis of oxygen surface functionalities and surface charge of the PAMC and, accordingly, charge transfer interaction seems to be responsible for the decolorisation mechanism. In addition, a complex interplay of electrostatics and dispersive interaction seem to be involved during the decolorisation process. CONCLUSION: A low‐cost agricultural waste product in the form of de‐oiled mustard cake was converted to an efficient adsorbent, PAMC, for use in decolorising raw as well as coloured sugar solutions. The physical, chemical, adsorption characteristics and raw sugar decolorisation efficiency of PAMC were determined and compared to those of commercial adsorbents. The colour removal efficiency of the PAMC is lower than that of commercial materials but it is cost effective and eco‐friendly as compared to existing decolorisation/refining processes. The availability of the raw material for the production of PAMC further demands its use on an industrial scale. Copyright © 2012 Society of Chemical Industry     

Biosensors For Monitoring Insecticides And Herbicides - A Survey

Biosensors for the detection of insecticides and herbicides have been reviewed. Direct, fast and easy determination of various insecticides - organophosphorus and carbamates, and herbicides has been achieved by integrating various biocomponents with different transducers. For the construction of biosensors, bioassay principles, effect of solvents and immobilization techniques used, and the compatibility of bioassay principle with the transducer has been discussed. The close integration of the biological events with the generation of a signal offers the potential for fabricating compact and easy-to-use analytical tools of high sensitivity and specificity. Their biological base makes them ideal for toxicological measurement of pesticides, while conventional techniques can only measure concentration. Screening of a particular source for biological component could be helpful to design a specific biosensor.     

A genetic algorithm for FMS part type selection and machine loading

Part type selection (PTS) and machine loading are two major problems in the production planning of flexible manufacturing systems. In this paper, we solve these problems by the use of genetic algorithms (GAs). We exploit the problem's MIP (mixed integer programming) model to make our GA more meaningful and less computation-intensive. The GA strategy is developed in three parts: solution coding, solution generation and solution recombination. In solution coding, we replace the original binary routing variables with integer variables and thus reduce the chromosome length significantly. In solution generation, the level of feasibility is the main concern. We divide the constraints into two categories: direct and indirect. The direct constraints involve only two variables each and are easily satisfied by context-dependent genes. Since the direct constraints form the major chunk of constraints, their satisfaction controls infeasibility to a large extent. The remaining indirect constraints are handled by the penalty function approach. The solution recombination involves crossover and mutation. The crossover is performed in two steps, the PTS swap followed by the routing swap, so that the feasibility level is not disturbed. With a similar intent, the mutation is allowed to operate only on selective genes. All the steps are illustrated with examples. Our GA is able to achieve optimum or near-optimum performance on a variety of objectives. A parametric study of GA factors is also carried out, indicating population size and mutation probability as influential parameters.     

Managing warehousing in an agile supply chain environment: an F-AIS algorithm based approach

In recent years, application of the agile concept in the manufacturing sector has been researched extensively to reduce the varying effect of customer demands. However, most of the research work is focused on the shop floor of different manufacturing processes, while issues concerning the control of warehouse scheduling in a supply chain have been neglected so far. Realising this in the present research an attempt has been made to address the scheduling aspect of a warehouse in an agile supply chain environment. To resolve the warehouse problem in this paper, the authors have proposed a new Fuzzy incorporated Artificial Immune System Algorithm (F-AIS). This algorithm encapsulates the salient features of a fuzzy logic controller and immune system. The proposed algorithm has been compared with genetic algorithm (GA), simulated annealing (SA) and artificial immune system (AIS) algorithm to reveal the efficacy of the proposed F-AIS algorithm.     

1998 ASEM Conference Information and Registration Form

Abstract:

Highly capital-intensive systems in domains such as transportation, infrastructure, defense and aerospace, and telecom have long operational life cycles and their stakeholders expect them to exhibit the necessary operational and performance characteristics during these long operational life spans. Often the results have been less than satisfactory, which has led many to envision alternative approaches to effectively sustaining such systems. Among the alternative approaches is Performance Based Logistics (PBL), whose essence is to define key system readiness and effectiveness criteria and to contract for threshold values of these criteria. The emphasis is in contracting for results, and not for resources as traditionally done.

This article is based on a literature survey conducted on the papers published in connection with this topic since the advent of the PBL initiative, as well as on numerous personal interviews entertained in programs in which the authors have been involved, and briefly surveys current practices in PBL-based contracting, highlighting the lessons learned and outlining the primary drawbacks observed. Finally this article proposes a framework for formulating more efficient and effective PBL contractual agreements and identifies the main topics or aspects of a successful PBL initiative. Experience shows that in order for a PBL contract to yield the desired results it is essential to have a thorough agreement on the metrics to be used to represent system effectiveness, as well as an agreed reward scheme that links reward to achieved effectiveness.