Compressibility and compactibility studies of chitosan,xanthan gum,and their mixtures

The compressibility and compactibility studies of binary mixtures containing chitosan (CS) and xanthan gum (XG) were highlighted in this article. The compressibility of the examined powders was studied according to Heckel and Gurnham equations. Results indicated that CS exhibits more ductile character than XG. Moreover, in this study percolation theory has been applied to the tensile strength of different compacts obtained from CS–XG mixtures. The obtained percolation thresholds showed that higher pressures must be applied to form compacts with a specific strength as the mass fraction of XG was increased. Additionally, the values of the maximum tensile strength showed that the percolation threshold of CS occurs at equal mass fraction of the two polymers. Scanning electron microscope, light microscope techniques, and molecular mechanical calculations were also conducted in order to study the interactions between CS and XG. The obtained results revealed that 1:1 ratio (by weight) represents the maximum interactions between the two polymers.     

Thromboxane synthase inhibitor, UK 38485, prevents renal injury in the rabbit isolated perfused kidney exposed to cold ischemia

Recent studies have indicated that, the administration of thromboxane A2 (TxA2) inhibitors improved renal functions in experimental renal allograft transplantation. Thus TxA2, a vasoconstrictor metabolite of arachidonic acid, may play a role in renal function and blood flow during hypothermic storage. The aim of the present study was to evaluate the cytoprotective effect of TxA2 synthase inhibitor, UK 38485, on altered renal function due to cold ischemia for 24 and 72 h. Experiments were performed in isolated perfused kidney from adult rabbits. Kidneys were perfused with Euro-Collins (EC) containing UK 38485 and incubated with the same solution in a beaker exposed to cold ischemia for 24 and 72 h. The same procedure was applied to the control kidneys in EC solution alone. Vascular responses and urinary output to noradrenaline, angiotensin II, endothelin-1, acetylcholine, and sympathetic stimulation were assessed as the functional activity of kidney. The addition of UK 38485 to EC solution increased the preservation time of kidney and protects the vascular endothelial regulatory functions and urine excretion when compared to EC alone. The results of the present study can be taken as an evidence of the cytoprotective effect of the UK 38485 and might be useful for kidney preservation.     

Loosely woven fabric model with viscoelastic crimped fibres for ballistic impact simulations

A computational micro‐mechanical material model of loosely woven fabric for non‐linear finite element impact simulations is presented in this work. The model is a mechanism incorporating the crimping of the fibres as well as the trellizing. The equilibrium of the mechanism allows the straightening of the fibres depending on the fibre tension. The contact force at the fibre crossover point determines the rotational friction dissipating a part of the impact energy. The stress–strain relationship is viscoelastic based on a three‐element model. The failure of the fibres is strain rate dependent. The model is implemented as user defined subroutine in the transient finite element code LS‐DYNA. The ballistic impact simulations with the model are in good agreement with the experimental results. Copyright © 2004 John Wiley & Sons, Ltd.     

Functional studies of twelve mutant V2 vasopressin receptors related to nephrogenic diabetes insipidus: molecular basis of a mild clinical phenotype

X-linked nephrogenic diabetes insipidus (NDI) is a rare disease with defective renal and extrarenal arginine vasopressin V2 receptor responses due to mutations in the AVPR2 gene in Xq28. To study the cause of loss of function of mutant V2 receptors, we expressed 12 mutations (N55H, L59P, L83Q, V88M, 497CC-->GG, deltaR202, I209F, 700delC, 908insT, A294P, P322H, P322S) in COS-7 cells. Eleven of these, including P322H, were characterized by a complete loss of function, but the mutation P322S demonstrated a mild clinical and in vitro phenotype. This was characterized by a late diagnosis without any growth or developmental delay and a significant increase in urine osmolality after intravenous 1-deamino[D-Arg8]AVP administration. In vitro, the P322S mutant was able to partially activate the Gs/adenylyl cyclase system in contrast to the other V2R mutants including P322H, which were completely inactive in this regard. This showed not only that Pro 322 is important for proper V2R coupling, but also that the degree of impairment is strongly dependent on the identity of the substituting amino acid. Three-dimensional modeling of the P322H and P322S mutant receptors suggested that the complete loss of function of the P322H receptor could be due, in part, to hydrogen bond formation between the His 322 side chain and the carboxyl group of Asp 85, which does not occur in the P322S receptor.     

Integrated definition modeling and Taguchi analysis of flexible manufacturing systems: aircraft industry application

In this paper, flexible manufacturing systems (FMS) are studied. Firstly, an FMS design approach is proposed using integrated definition for function methodology. A systematic layout design and performance evaluation scheme is presented and detailed using this modeling framework. Then, the proposed approach is carried out with a case study from an aircraft industry to convert an existing traditional production system to FMS. To improve the system performance, a simulation-based method with Taguchi approach consisting of multiproducts is utilized. The objective is to find the machine and the product mix that achieves the maximum utilization while minimizing the cycle time. FMS system performance has been greatly improved by determining the most advantageous level of system components. It has also shown that FMS is a practicable production system in aircraft industry.     

High-pressure processing of fish and shellfish products: Safety,quality, and research prospects

Seafood products have been one of the main drivers behind the popularity of high-pressure processing (HPP) in the food industry owing to a high demand for fresh ready-to-eat seafood products and food safety. This review provides an overview of the advanced knowledge available on the use of HPP for production of wholesome and highly nutritive clean label fish and shellfish products. Out of 653 explored items, 65 articles published during 2016–2021 were used. Analysis of the literature showed that most of the earlier work evaluated the HPP effect on physicochemical and sensorial properties, and limited information is available on nutritional aspects. HPP has several applications in the seafood industry. Application of HPP (400–600 MPa) eliminates common seafood pathogens, such as Vibrio and Listeria spp., and slows the growth of spoilage microorganisms. Use of cold water as a pressure medium induces minimal changes in sensory and nutritional properties and helps in the development of clean label seafood products. This technology (200–350 MPa) is also useful to shuck oysters, lobsters, crabs, mussels, clams, and scallops to increase recovery of the edible meat. High-pressure helps to preserve organoleptic and functional properties for an extended time during refrigerated storage. Overall, HPP helps seafood manufacturers to maintain a balance between safety, quality, processing efficiency, and regulatory compliance. Further research is required to understand the mechanisms of pressure-induced modifications and clean label strategies to minimize these modifications.     

On the performance of wireless sensor networks with QSSK modulation in the presence of co-channel interference

This paper proposes the use of quadrature space shift keying (QSSK) modulation for wireless sensor networks (WSNs). QSSK is a multiple input multiple output communication protocol that attracted substantial interest due to several promised inherent advantages. It has been shown in literature that QSSK scheme achieves high spectral efficiency with low average error probability, high energy efficiency, and very simple transmitter and receiver architectures. Hence, its use in WSNs is very promising to ameliorate the major limitations of such networks. The performance of a WSN with QSSK modulation and in the presence of co-channel interference is studied in this paper. A closed form expression for the average pair wise error probability is derived and used to obtain a tight upper bound on the overall average bit error ratio. Obtained results verified the superiority of QSSK scheme as compared to traditional modulation techniques especially for high spectral efficiency.     

Database management in a microcomputer-controlled IC tester

A database suitable for microcomputer-controlled static testing of digital ICs is proposed. The database contains sufficient information to minimize the interaction between the operator and the IC tester. The test sequence provided in the database facilitates the detection of all possible defects in ICs including those due to ‘stuck’ pins. The validity of the database is en- sured by developing suitable hardware and software.     

Algerian montmorillonite as a builder in a detergent powder

Algerian montmorillonite treated with sodium chloride was used as a substitute for the builders sodium tripolyphosphate (STPP) and sodium sulfate in a detergent powder. The following performance parameters of the substituted composition powder were examined: pH, foaming, cleaning, sequestering, and ion exchange capacities. The latter factors remained the most important ones for effective detergency. Despite anticipated improvement in hard water ion removal, constant detergency results were observed with the treated montmorillonite-containing powder. This level of efficacy does not meet the cost-effectiveness of a standard detergent powder containing STPP.     

Micromechanical Modeling of the Viscoelastic Behavior of Asphalt Mixtures Using the Discrete-Element Method

This paper presents a methodology for analyzing the viscoelastic response of asphalt mixtures using the discrete-element method (DEM). Two unmodified (neat) and seven modified binders were mixed with the same aggregate blend in order to prepare the nine hot mix asphalt (HMA) mixtures used in this study. The HMA microstructure was captured using images of vertically cut sections of specimens. The captured grayscale images were processed into black and white images representing the mastic and the aggregate phases, respectively. These microstructure images were used to represent the DEM model geometry. Rheological data for the nine binders were obtained using the dynamic shear rheometer. These data were used to estimate the parameters of the viscoelastic contact models that define the interaction among the mix constituents. The DEM models were subjected to sinusoidal loads similar to those applied in the simple performance test (SPT). The DEM model predictions compared favorably with the SPT measurements. However, the simulation results tended to overpredict the dynamic modulus, E*, for mixtures made with neat binders and underpredict E* for those that consisted of modified binders. The DEM models gave mix phase angles, ?mix, higher than the experimental measurements.