Non-monotonic salt concentration dependence of inverted electrokinetic flow

Modeling of electrokinetic flows is crucial to understand numerous phenomena associated with electrochemistry, biophysics, and colloidal science. Here, we incorporate the modified Gaussian renormalized fluctuation theory into transport equations for electrolyte solutions to study the ion-correlation-induced inversion of electrokinetic flows, also known as charge inversion. We are able to capture the non-monotonic dependence of inverted streaming current and reversed electrophoretic mobility on salt concentration. By analyzing the double-layer structure, we elucidate that this non-monotonicity is a consequence of the competition between spatially varying ion correlations and the translational entropy of the ions. We find that for practical values of surface charge densities, the excluded volume effect does not play any significant role. In a significant improvement over existing theories, our theoretical predictions are in quantitative agreement with experimental measurements for charge inversion in trivalent salts.     

Techniques to measure sorption and migration between small molecules and packaging. A critical review

The mass transfer parameters diffusion and sorption in food and packaging or between them are the key parameters for assessing a food product's shelf‐life in reference to consumer safety. This has become of paramount importance owing to the legislations set by the regulated markets. The technical capabilities that can be exploited for analyzing product–package interactions have been growing rapidly. Different techniques categorized according to the state of the diffusant (gas or liquid) in contact with the packaging material are emphasized in this review. Depending on the diffusant and on the analytical question under review, the different ways to study sorption and/or migration are presented and compared. Some examples have been suggested to reach the best possible choice, consisting of a single technique or a combination of different approaches. © 2014 Society of Chemical Industry     

Fabrication of portable solar thermal bank for indoor cooking

The aim of this report is to build a portable solar thermal bank based on a Scheffler reflector that is capable of boiling-type cooking using HITEC as a thermal storage material. This report reviews the problems related to solar cooking and evaluates the novel layout of a portable solar thermal bank which includes a daily thermal storage vessel. This stove is in the shape of a cylindrical container filled with phase-changing latent heat storage material. Inside the container, we provide a small gap taking into account the volumetric expansion of the phase change material (PCM) during the melting process. The solar thermal bank is charged in the sun. It is placed directly for a few hours under the focus of a Scheffler reflector, which charges the solar thermal bank with enough thermal energy stored. After a while, the cooking process can be completed by users using that stored heat. The top cavity is used as a cooking pot in a solar thermal bank. Cooking meals do not require direct sunlight, which is typical for most solar cookers. The portable solar thermal bank is an alternative for low-income households and adapts to local traditions of indoor cooking. It is portable and can be used safely to cook indoors or outdoors. In this study, a solar cooker with a thermal storage device was developed using a PCM. The size of the stove has been calculated by calculating the energy consumption for two to three people. HITEC salt has been chosen as a phase change material for thermal storage, which will be used for cooking when there is no sunlight. It enhances the applicability of solar cooking and preserves cooking possibilities using energy stored throughout the day at low production costs.     

A synthesis method for multicomponent distillation sequences with fewer columns

An easy‐to‐use matrix‐based method for the systematic synthesis of distillation configurations using less than n‐1 columns to separate any zeotropic n‐component feed into n product streams is described. The method is easily extended to obtain additional thermally coupled configurations. The only information needed to generate the configurations is the number of components in the feed, or equivalently, the number of distinct composition final product streams. We have successfully enumerated configurations for feeds containing up to eight components. This has resulted in a large number of hitherto unknown configurations even for four‐component separations. Some of the novel configurations generated using the method have substantially lower heat duty than the previously known fewer column configurations for a four‐component feed separation. Therefore, it is essential to include these novel configurations in the search space to find the optimal distillation configuration with fewer columns for a given application. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2479–2494, 2012     

Influence of unit operations on the levels of polyacetylenes in minimally processed carrots and parsnips: An industrial trial

Carrots and parsnips are often consumed as minimally processed ready-to-eat convenient foods and contain in minor quantities, bioactive aliphatic C17-polyacetylenes (falcarinol, falcarindiol, falcarindiol-3-acetate). Their retention during minimal processing in an industrial trial was evaluated. Carrot and parsnips were prepared in four different forms (disc cutting, baton cutting, cubing and shredding) and samples were taken in every point of their processing line. The unit operations were: peeling, cutting and washing with chlorinated water and also retention during 7 days storage was evaluated. The results showed that the initial unit operations (mainly peeling) influence the polyacetylene retention. This was attributed to the high polyacetylene content of their peels. In most cases, when washing was performed after cutting, less retention was observed possibly due to leakage during tissue damage occurred in the cutting step. The relatively high retention during storage indicates high plant matrix stability. Comparing the behaviour of polyacetylenes in the two vegetables during storage, the results showed that they were slightly more retained in parsnips than in carrots. Unit operations and especially abrasive peeling might need further optimisation to make them gentler and minimise bioactive losses.     

A cohesive modeling technique for theoretical and experimental estimation of damping in serial robots with rigid and flexible links

Dynamic model incorporating damping characteristics, namely joint damping and structural damping in flexible links, of the serial robots with rigid and flexible links is presented. A novel procedure, based on the unified approach of theoretical formulation and analysis of experimental data, is proposed for the estimation of damping coefficients. First, the dynamic model of a robotic system with rigid and flexible links is presented. Next, the modifications in the dynamic model due to the considerations of damping characteristics of joints and structural damping characteristics of the flexible links are presented. A systematic methodology based on analysis of data obtained from experiments is presented for estimation and determination of damping coefficients of rigid-flexible links. The determination of joint damping coefficients, is based on the logarithmic decay of the amplitude of the oscillations of robotic links, while the structural damping coefficients are estimated mainly using the modal analysis and the method of evolving spectra. The method of evolving spectra, based on the Fast Fourier Transform of the decay of the amplitude in structural vibrations of the robot links in progressive windows is used to estimate the structural damping ratios while the critical structural coefficients are determined using the modal analysis. The methodology is illustrated through a series of simple experiments on simple robotic systems. The experimental results are then compared with the simulation results incorporating the damping coefficients determined using the proposed procedure. The comparisons leads to the validation of the proposed dynamic modeling technique, modeling of the damping characteristics, and the method proposed for estimation of damping coefficients for rigid-flexible link robotic systems.     

12 nm tunable WDM source using an integrated laser array

A 12 nm tunable source with up to 15 mW fibre coupled power has been fabricated by integrating four DFB lasers and a booster amplifier to provide a single output. High-yield and low-cost techniques are used, such as quarter-wave-shifted phase-masks for wavelength definition and an integration technique with only two regrowths     

Study of chemiresistor type CNT doped polyaniline gas sensor

The composite thin films of polyaniline (Pani) with multiwall carbon nanotube (MWNT) and single wall carbon nanotube (SWNT) for hydrogen gas sensing application are presented in this paper. Polyaniline (Pani) was synthesized by chemical oxidative polymerization of aniline using ammonium persulfate in acidic medium. The SWNT and MWNT were doped in Pani in presence of champhor sulfonic acid (CSA) by solution mixing method. Thin films of CNT/Pani composites were prepared by spin coating method. Finally, the response of these composite films for hydrogen gas was evaluated by monitering the change in electrical resistance at room tempeature. It is observed that the SWNT/Pani and MWNT/Pani composite films show a higher response as compare to pure Pani. The structural and optical properties of these composite films have been characterised by X-ray diffraction (XRD) and UV–visible spectroscopy respectively. Surface morphology of these films has also been characterised by optical microscopy.     

Synthesis and characterization of some new acid salts of 8H-2,6,8,9,10-Pentaazabicyclo[5,2,1]-deca-2,5,9,10-tetraene

Abstract

Some new acid salts of 8H-2,6,8,9,10-pentaazabicyclo[5,2,1]-deca-2,5,9,10-tetraene were prepared and characterised by spectral data (IR, ¹H-NMR and Mass) and elemental analysis. The purity of these compounds was confirmed by HPLC and was found to be > 95% pure. In addition, the compounds were subjected to impact and friction sensitivity tests and were found very safe.