Loop‐Mediated Isothermal Amplification (LAMP): A Rapid and Sensitive Tool for Quality Assessment of Meat Products

Loop‐mediated isothermal amplification (LAMP) is a novel method that amplifies target nucleic acids under isothermal conditions. It is a rapid, specific, and sensitive method, which does not require costly thermal cyclers for the detection of nucleic acids. Thus, it is suitable for on‐site detection assays under low‐resource settings. It can also be integrated on compact lab‐on‐a‐chip devices for the development of micro‐total analysis systems. This review discusses LAMP‐based methods, as well as LAMP‐based centrifugal, microfluidic, and other fluid‐handling devices, which have been developed for the assessment of meat quality parameters that are related to the presence or absence of nucleic acids, for example, animal species identification and microbiological quality. Advances in improving the rapidity, specificity, and sensitivity of LAMP techniques for the assessment of these meat quality parameters are also discussed in this review.     

Arbitrary shaped ice particle melting under the influence of natural convection

This work is devoted to numerical simulations of an arbitrary shaped ice particle melting inside water under the influence of natural convection. Specifically, four different shapes of the ice particle have been studied: sphere, cylinder, cross shaped cylinder, and irregular sphere with radial bumps on its surface. A 2D axisymmetric particle‐resolved numerical model has been employed on a fixed grid to study the detailed melting dynamics of an ice particle. The solid‐liquid interface is treated as a porous medium characterized by the permeability coefficient which is used to damp the velocity values inside the interface. The model results have been compared with an existing experimental results produced by A. Shukla et al. (Metal Mater Trans B. 2011; 42(1):224–235). Very good agreement between our predictions and experimental data have been achieved. Based on the analysis of numerical simulation results, melting process is found to advance through two distinct regimes, namely, establishment of the natural convection and active melting of ice particle exhibiting substantial amount of fluid‐particle interactions. A set of dimensionless parameters have been identified to distinguish between regimes. Finally, we developed a semi‐empirical to predict the melting of any arbitrary shaped ice particle and validated it against the particle‐resolved numerical simulation and experimental results. The comparison showed good agreement. Finally, the presented semi‐empirical model can be used as sub‐grid model in Euler‐Lagrange based numerical models to study the phase change phenomena in particulate flow systems. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3158–3176, 2017     

Magnetic particles for sugar separation from sulphuric acid solution generated during nano‐crystalline cellulose production

Nano‐crystalline cellulose (NCC) is a renewable material having different applications ranging from drug delivery to a reinforcing filling agent in polymer synthesis. Concentrated sulphuric acid is used to hydrolyze cellulosic biomass to obtain NCC. Manufacturers are keen to reuse the diluted acid solution left after the process. However, the presence of mono and oligosaccharides makes it unsuitable for repeated use. About 99 % of these compounds have been successfully separated from the acid solution by employing NaOH‐treated magnetic particles developed during this investigation. It has been observed that by NaOH treatment, zeta potential of the magnetic particles could be increased from +11 mV to +37.5 mV; correspondingly, sugar removal efficiency was increased from 23.04 % to more than 99 %. Thus a direct correlation between the change in zeta potential of the particles and sugar separation efficiency has been observed.     

Thermal modeling and performance analysis of industrial-scale metal hydride based hydrogen storage container

In this paper, a performance analysis of a metal hydride based hydrogen storage container with embedded cooling tubes during absorption of hydrogen is presented. A 2-D mathematical model in cylindrical coordinates is developed using the commercial software COMSOL Multiphysics 4.2. Numerical results obtained are found in good agreement with experimental data available in the literature. Different container geometries, depending upon the number and arrangement of cooling tubes inside the hydride bed, are considered to obtain an optimum geometry. For this optimum geometry, the effects of various operating parameters viz. supply pressure, cooling fluid temperature and overall heat transfer coefficient on the hydriding characteristics of MmNi_4.6Al_0.4 are presented. Industrial-scale hydrogen storage container with the capacity of about 150 kg of alloy mass is also modeled. In summary, this paper demonstrates the modeling and the selection of optimum geometry of a metal hydride based hydrogen storage container (MHHSC) based on minimum absorption time and easy manufacturing aspects.     

Rapid Quantification of Low-Viscosity Acetyl-Triacylglycerols Using Electrospray Ionization Mass Spectrometry

Acetyl‐triacylglycerols (acetyl‐TAG) possess an sn‐3 acetate group, which confers useful chemical and physical properties to these unusual triacylglycerols (TAG). Current methods for quantification of acetyl‐TAG are time consuming and do not provide any information on the molecular species profile. Electrospray ionization mass spectrometry (ESI–MS)‐based methods can overcome these drawbacks. However, the ESI–MS signal intensity for TAG depends on the aliphatic chain length and unsaturation index of the molecule. Therefore response factors for different molecular species need to be determined before any quantification. The effects of the chain length and the number of double‐bonds of the sn‐1/2 acyl groups on the signal intensity for the neutral loss of short chain length sn‐3 groups were quantified using a series of synthesized sn‐3 specific structured TAG. The signal intensity for the neutral loss of the sn‐3 acyl group was found to negatively correlated with the aliphatic chain length and unsaturation index of the sn‐1/2 acyl groups. The signal intensity of the neutral loss of the sn‐3 acyl group was also negatively correlated with the size of that chain. Further, the position of the group undergoing neutral loss was also important, with the signal from an sn‐2 acyl group much lower than that from one located at sn‐3. Response factors obtained from these analyses were used to develop a method for the absolute quantification of acetyl‐TAG. The increased sensitivity of this ESI–MS‐based approach allowed successful quantification of acetyl‐TAG in various biological settings, including the products of in vitro enzyme activity assays.     

Micromechanics of spatially uniform heterogeneous media: A critical review and emerging approaches

Outside of the classical microstructural detail-free estimates of effective moduli, micromechanical analyses of macroscopically uniform heterogeneous media may be grouped into two categories based on different geometric representations of material microstructure. Analysis of periodic materials is based on the repeating unit cell (RUC) concept and the associated periodic boundary conditions. This contrasts with analysis of statistically homogeneous materials based on the representative volume element (RVE) concept and the associated homogeneous boundary conditions. In this paper, using the above classification framework we provide a critical review of the various micromechanical approaches that had evolved along different paths, and outline recent emerging trends. We begin with the basic framework for the solution of micromechanics problems independent of microstructural representation, and then clarify the often confused RVE and RUC concepts. Next, we describe classical models, including the available RVE-based models, and critically examine their limitations. This is followed by discussion of models based on the concept of microstructural periodicity. In the final part, two recent unit cell-based models, which continue to evolve, are outlined. First, a homogenization technique called finite-volume direct averaging micromechanics theory is presented as a viable and easily implemented alternative to the mainstream finite-element based asymptotic homogenization of unit cells. The recent incorporation of parametric mapping into this approach has made it competitive with the finite-element method. Then, the latest work based on locally-exact solutions of unit cell problems is described. In this approach, the interior unit cell problem is solved exactly using the elasticity approach. The exterior problem is tackled with a new variational principle that successfully overcomes the non-separable nature of the overall unit cell problem.     

The effect of hydrogen crossover on open-circuit voltage in polymer electrolyte membrane fuel cells

Even though the measured open-circuit voltage in a H₂-O₂ PEM fuel cell is invariably about 200-250 mV lower than that predicted from thermodynamics (1.229 V at 25 °C), there is no unequivocal explanation of this phenomenon available in the literature, although several hypotheses exist. Based on a theoretical model of mixed potential with a priori parameters, it is shown here that this voltage loss under open-circuit conditions can be attributed exclusively to hydrogen crossover and the resulting oxygen reduction reaction overpotential at the cathode. The analytical model predictions agree well with available experimental results.     

Application of geographic information systems in construction safety planning

Execution schedule and 2D drawings are generally used for hazards identification in the construction safety planning process. Planner visualises 2D drawings into a 3D model and mentally links its components with the respective activities defined in the schedule to understand the execution sequence in safety planning. Sequence interpretation and accordingly the hazards identification vary with the level of experience, knowledge and individual perspective of the safety planner. Therefore, researchers suggest the use of four dimensional (4D) modelling or building information modelling (BIM) to create the simulation of construction process by linking execution schedule with the 3D model. Both however lack in the features like: generation and updating of schedule, 3D components editing, topography modelling and geospatial analysis within a single platform which is now a major requirement of the construction industry. This work facilitates 4D modelling, geospatial analysis and topography modelling in the development of safe execution sequence by using geographic information systems (GIS), both 3D model along with its surrounding topography and schedule were developed and linked together within the same environment. During safety review process if planned sequence results a hazard situation, it may be corrected within the GIS itself before actual implementation. Paper also discusses the use of GIS in the development of safety database from which safety information are retrieved and linked with the activities of the schedule or components of a building model. 4D modelling along with topographical conditions and safety database in a single environment assist safety planner in examining what safety measures are required when, where and why. Developed methodology was tested on a real life project in India, lessons learned from the implementation have been discussed in the potential benefits and limitations section. At last, paper highlights major research areas for further improvements.     

Gecko‐Inspired Dry Adhesive for Robotic Applications

Most geckos can rapidly attach and detach from almost any kind of surface. This ability is attributed to the hierarchical structure of their feet (involving toe pads, setal arrays, and spatulae), and how they are moved (articulated) to generate strong adhesion and friction forces on gripping that rapidly relax on releasing. Inspired by the gecko's bioadhesive system, various structured surfaces have been fabricated suitable for robotic applications. In this study, x–y–z asymmetric, micrometer‐sized rectangular flaps composed of polydimethylsiloxane (PDMS) were fabricated using massively parallel micro‐electromechanical systems (MEMS) techniques with the intention of creating directionally responsive, high‐to‐low frictional‐adhesion toe pads exhibiting properties similar to those found in geckos. Using a surface forces apparatus (SFA), the friction and adhesion forces of both vertical (symmetric) and angled/tilted (x–y–z asymmetric) microflaps under various loading, unloading and shearing conditIons were investigated. It was found that the anisotropic structure of tilted microflaps gives very different adhesion and tribological forces when articulated along different x–y–z directions: high friction and adhesion forces when articulated in the y–z plane along the tilt (+y) direction, which is also the direction of motion, and weak friction and adhesion forces when articulated against the tilt (–y) direction. These results demonstrate that asymmetric angled structures, as occur in geckos, are required to enable the gecko to optimize the requirements of high friction and adhesion on gripping, and low frictional‐adhesion on releasing. These properties are intimately coupled to a (also optimum) articulation mechanism. We discuss how both of these features can be simultaneously optimized in the design of robotic systems that can mimic the gecko adhesive system.