Determination of the equilibrium, kinetic and thermodynamic parameters of adsorption of copper(II) ions onto seeds of Capsicum annuum

Adsorption of copper ions onto Capsicum annuum (red pepper) seeds was investigated with the variation in the parameters of pH, contact time, adsorbent and copper(II) concentrations and temperature. The nature of the possible adsorbent and metal ion interactions was examined by the FTIR technique. The copper(II) adsorption equilibrium was attained within 60 min. Adsorption of copper(II) ions onto C. annuum seeds followed by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Maximum adsorption capacity (q(max)) of copper(II) ions onto red pepper seeds was 4.47x10(-4) molg(-1) at 50 degrees C. Three kinetic models including the pseudo-first-order, pseudo-second-order and intraparticle diffusion equations were selected to follow the adsorption process. Kinetic parameters such as rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was indicated that the adsorption of copper(II) ions onto C. annuum seeds could be described by the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 60 min, but diffusion is not only the rate controlling step. Thermodynamics parameters such as the change of free energy, enthalpy and entropy were also evaluated for the adsorption of copper(II) ions onto C. annuum seeds.     

Spreadsheet assisted learning of industrial control engineering

Spreadsheet programs can be used as a tool for computations and graphical analysis to enhance the learning process. This paper show how spreadsheet programs may be used in the learning of industrial control engineering. Two examples are given of transient step response, and Polar plot.     

Isolation and preparation of colonies grown on soft agar for ultrastructural investigation

Preparation of cell colonies grown on soft agar for electron microscopic examination is tedious. Mechanical damage to cells can occur during the process of colony removal. A procedure which permits rapid colony removal and preserves the integrity of the individual colony for ultrastructural examinations is described in this paper.     

Structural differences exhibited by networks prepared by chemical or photochemical reactions II — Thermoelastic properties

Thermoelastic properties and swelling measurements were used to characterise networks obtained either by peroxide curing or by photocrosslinking. In agreement with previous studies, it was shown, on the one hand that the measured value of the average molecular weight of a network strand (M _c) depends on its method of determination and that the ratio M _cT/M _cv2m is a characteristic of each crosslinking process, on the other hand photo-crosslinked materials exhibit a more homogeneous distribution of the crosslink points than do peroxide cured samples. Important parameters such as f_e/f, the energetic contribution to the equilibrium retractive force, and d In < r²> ₀/dT, the temperature coefficient of the unperturbed dimension of the macromolecular chain, were determined.     

A simple recursive scheme for adjusting the contention window size in IEEE 802.11e wireless ad hoc networks

The IEEE 802.11e standard has been introduced recently for providing Quality of Service (QoS) capabilities in the emerging wireless local area networks. This standard introduces a contention window based Enhanced Distributed Channel Access (EDCA) technique that provides a prioritized traffic to guarantee the minimum bandwidth needed for time critical applications. However, the EDCA technique resets the Contention Window (CW) of the mobile station statically after each successful transmission. This static behavior does not adapt to the network state since it reduces the network usage and results in bad performance and poor link utilization whenever the demand for link utilization increases. This paper proposes a new adaptive differentiation technique for IEEE 802.11e Wireless Local Area Networks that takes into account the network state before resetting the contention window. In the new technique, the congestion level of the network is sensed by using previous CW values. Three other enhancement techniques that focus on network adaptation are also discussed. Their main limitations are the high complexity of the implemented algorithms and their slow adaptation to the network state when the channel experiences bursty traffic. The proposed technique is compared to the original differentiation techniques of IEEE 802.11a and IEEE 802.11e standards, as well as to the enhancement schemes. Results show that the proposed adaptive technique outperforms IEEE 802.11e and is comparable to the other enhancement schemes while maintaining relatively low complexity requirements.     

An Auto-correlation Function Based Technique for Discrimination of Internal Fault and Magnetizing Inrush Current in Power Transformers

Abstract—This article presents an efficient method for discriminating magnetizing inrush and internal fault currents in three-phase transformers based on the auto-correlation function. For each phase, the auto-correlation function of the differential current is calculated for a specified range of lags. Their standard deviation is determined in the next step. Criterion function is simply defined as the difference between the maximum and minimum of the auto-correlation function lags standard deviations for the three phases. Performance of the proposed method is evaluated and compared with eight well-known methods by a large number of simulation and experimental data, covering different cases. The results confirm that the proposed technique is more efficient than the other methods from speed response, reliability, and accuracy points of view. To eliminate the current transformer saturation impact on the performance of the method, the currents are compensated by a current transformer saturation correction algorithm. Also, the proposed algorithm is evaluated in the case of a transformer that is fed through a feeder with series capacitors.     

Mathematical representation of bolted-joint stiffness: A new suggested model

Joint member stiffness in a bolted connection directly influences the safety of a design in regard to both static and fatigue loading, as well as in the prevention of separation in the connection. This work provides a new simple model for computing the member stiffness in bolted connections for both fully and partially developed stress envelope fields. The new model is built using a stress distribution polynomial of third order. Finite element analysis (FEA) is performed for some joints geometries, and the results are used to estimate the best analytical envelope angle in the proposed analytical model that gives suitable convergence between the compared results. An experimental effort is exerted to validate the accuracy of a suggested model. When analytical results are compared with FEA results and experimental data, the maximum absolute percentage errors are found to be 2.69 and 14.69, respectively. Also, a good agreement is obtained when the analytical results are compared with other researchers’ results.     

Integrating blood cell mechanics,platelet adhesive dynamics and coagulation cascade for modelling thrombus formation in normal and diabetic blood

Normal haemostasis is an important physiological mechanism that prevents excessive bleeding during trauma, whereas the pathological thrombosis especially in diabetics leads to increased incidence of heart attacks and strokes as well as peripheral vascular events. In this work, we propose a new multiscale framework that integrates seamlessly four key components of blood clotting, namely transport of coagulation factors, coagulation kinetics, blood cell mechanics and platelet adhesive dynamics, to model the development of thrombi under physiological and pathological conditions. We implement this framework to simulate platelet adhesion due to the exposure of tissue factor in a three-dimensional microchannel. Our results show that our model can simulate thrombin-mediated platelet activation in the flowing blood, resulting in platelet adhesion to the injury site of the channel wall. Furthermore, we simulate platelet adhesion in diabetic blood, and our results show that both the pathological alterations in the biomechanics of blood cells and changes in the amount of coagulation factors contribute to the excessive platelet adhesion and aggregation in diabetic blood. Taken together, this new framework can be used to probe synergistic mechanisms of thrombus formation under physiological and pathological conditions, and open new directions in modelling complex biological problems that involve several multiscale processes.     

Proteins degradation value in cured meat product made from M. Cutaneous-omo brachialis muscle of bovine

We analyzed differences in some physicochemical parameters of proteins in shoulder rose (M. Cutaneous-omo brachialis) muscle as a result of beef processing to produce pastirma. Samples from processed muscles showed significantly increased concentrations of extracted proteins, especially of H₂O P-ex and Guba-Straub–adenosine triphosphate solution (P < 0.01), as a result of the salting–curing process. The salt-curing process was likely to have an important effect on the extractability of muscle proteins such as myosin heavy chain (MHC) and water-soluble proteins, possibly as a result of releasing some proteins from each other and cleaving the structures between certain proteins. The fluorescence intensities of processed samples were higher than those of the control samples at all guanidine hydrochloride concentrations. The hydrophobicity also increased on account of new compounds that were created during the pastirma-making process. Since the process of making pastirma lasts about 4 weeks (drying), the metmyoglobin content was greatly increased in pastirma samples compared with the unprocessed samples (by as much as 57 %). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis results conceived that during processing of pastirma products, MHC and other muscle proteins degraded into polypeptides with smaller molecular weight lower than 15-kDa. The results of this study demonstrated that meat processing promoted the enzymatic digestion of some proteins, and the differences in composition between the control and pastirma samples were thus likely to be owing to protein degradation. The traditional pastirma-making process hence has no negative impact on the structure of the muscle and produces a firmer-textured.     

Synthesis of 2-imino-1,3-dithiolanes containing trimethylsilylethynylthiolato groups

An efficient, eco-friendly, and simple one-pot approach for the synthesis of 2-imino-1,3-dithiolanes via reaction of allyl chloride, primary amines, carbon disulfide, and I₂ under solvent-free conditions is presented. The obtained 5-iodomethyl-2-imino-1,3-dithiolanes were converted into silyl-protected terminal alkynyl sulfides substituted 2-imino-1,3-dithiolanes by treatment with lithium 2,2,2-tris(trimethylsilyl)ethanedithioate, produced by the reaction of tris(trimethylsilyl)methyllithium (TsiLi) with CS₂.