Mechanical and vibration isolation behaviour of acrylonitrile-butadiene rubber/multi-walled carbon nanotube composite machine mounts

An effective analytical-experimental test method is used in the current work to characterize the vibration isolation performance of nitrile-butadiene rubber (NBR) reinforced with multi-walled carbon nanotubes (MWCNTs). A series of specimens were manufactured with 10 different NBR/MWCNTs concentrations (0 to 20wt% MWCNTs). In order to determine the static compression stiffness and hysteresis of the mounts, compression and cyclic tests were conducted. The vibration isolation properties were determined through the analysis of the transmissibility of a suitably designed test system. NBR’s mechanical properties and vibration isolation properties were improved with the addition MWCNTs, suggesting that the enhancement of NBR with MWCNTs was rather effective. Considering the obtained results, the dynamic stiffness of NBR and its capacity to isolate vibration can be adjusted by controlling the proportion of MWCNTs.     

Recovery and partial purification of thermophilic β-xylosidase derived from recombinant Bacillus megaterium MS941 by aqueous two-phase system

A polymer–salt-based aqueous two-phase system (ATPS) was developed for the effective extraction and purification of extracellular β-xylosidase from the fermentation broth of recombinant Bacillus megaterium MS941. The effect of molecular weight (MW) of polyethylene glycol (PEG), tie-line length (TLL), volume ratio (V_R), crude loading and pH on the recovery performance was evaluated. Under the optimal extraction conditions, β-xylosidase was successfully purified up to 23-fold with a recovery yield of 99% in the bottom salt-rich phase at PEG 4,000/potassium phosphate ATPS comprising TLL of 41.8, V_R of 2.3, crude loading (C_L) of 30% (w/w) at pH 6.     

Computer Vision System (CVS) for In-Line Monitoring of Visual Texture Kinetics During Shrimp (Penaeus Spp.) Drying

In this study, the effects of drying medium temperature and velocity were surveyed on the image texture features of shrimp (Penaeus spp.) batches in a dryer equipped with a perpendicular dual-view computer vision system (CVS). This was carried out by applying an innovative rotation- and scale-invariant image texture processing approach with the capability of eliminating the effects of sample shrinkage on the visual textural features. Moreover, the variations in image texture parameters were investigated with moisture ratio, color, and geometrical characteristics of the shrimp samples. Drying experiments were conducted at hot air drying (HAD) temperatures of 50–90°C and superheated steam drying (SSD) temperatures of 110–120°C with drying medium velocities of 1–2 m/s. Several configurations of a multilayer perceptron artificial neural network (MLP-ANN) were also used to predict the moisture ratio and the geometrical characteristics of the shrimp batch using the image texture parameters. Generally, the image texture features were significantly affected by drying medium temperatures (p < 0.01), and the effects of drying medium velocities on the textural properties were nonsignificant (p > 0.05). Additionally, the higher drying temperatures generated products with uniform and regular texture patterns. The SSD produced samples with somewhat nonuniform and irregular texture patterns compared with HAD at 90°C. Finally, selected MLP-ANN topologies successfully predicted the moisture ratio and the geometrical characteristics of the shrimp batch using the textural properties with correlation coefficients higher than 0.99.     

Development of a Correlation Test Specimen for Highly Deformable Adhesive Systems

A new adhesive test specimen design was developed which embodied several key attributes, the most important of which was inclusion of tension, mixed-mode, and shear deformation mechanisms. The specimen design was easy to manufacture, required only simple tension testing equipment to test, and provided simple specimen geometry and boundary conditions for use in finite element model correlation exercises. By design, the individual failure points for each of the deformation mechanisms within the test specimen were separated and could be related directly to characteristics of the force versus displacement information from the experimental test. Finite element predictions using a Gurson constitutive model with element deletion at failure were generated and compared with experimental test results. It was found that while the order of failure modes within the prediction was the same as that found within the test, the element deletion technique yielded an abrupt change between failure modes not seen in the experimental test, and that a more complex numerical representation of failure would be a valuable development. Overall, the test specimen development was successful in providing a simple and repeatable method by which complex cohesive failure modes in a bonded system could be evaluated and correlated back to predictive tests.     

LIQUID-LIQUID MIXING IN STIRRED VESSELS: A REVIEW

Liquid-liquid mixing is a key process in industries that is commonly accomplished in mechanical agitation systems. Liquid-liquid mixing performance in a stirred tank can be evaluated by various parameters, namely minimum agitation speed, mixing time, circulation time, power consumption, drop size distribution, breakup and coalescence, interfacial area, and phase inversion. The importance of these liquid-liquid mixing parameters, the measurement method, and the results are discussed briefly. Input parameters such as impeller type, power number, flow pattern, number of impellers, and dispersed phase volume fraction, in addition to physical properties of phases such as viscosity and density, are reviewed. Scale-up aspects are also included.     

Synthesis of polyamides from p-Xylylene glycol and dinitriles

A series of polyamides were prepared by direct polyamidation of the p-Xylylene glycol with various commercially available dinitriles via Ritter reaction. All the synthesized polyamides showed good solubility in amide type solvents such as N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, and dimethyl sulfoxide. They exhibited inherent viscosities in the range of 0.25–0.62 dl/g. Elemental analysis, differential scanning calorimetry, thermogravimetric analysis, infrared and H¹-NMR spectroscopies were used to characterize the polymers. According to the DSC analysis, the glass transition temperatures of the polyamides were found to be 95–174°C. Thermogravimetric analysis indicated that the polymers show the 10% weight loss temperatures in the range of 250–350°C.     

Predicting PVT properties of Egyptian crude oils by a modified Soave–Redlich–Kowng equation of state

The study aims to predict the physical properties of Egyptian crude oils using modified Soave–Redlich–Kowng equation of state. The modification was theoretically developed and then performed by using data of 43 black oil samples representing all active oil producing areas of Egypt. The equation enables to predict the bubble-point pressure, oil formation volume factor, gas–oil ratio, oil density, crude oil gravity, gas gravity and gas formation volume factor of black oils with average relative errors ranging from 0.01% to 10.713%.Calculation sensitivity of the proposed MSRKE is determined by testing four oil samples collected from different locations in Egypt and comparing the measured PVT properties with those calculated from MSRKE. These evaluations show an excellent agreement between the measured properties and calculated ones.The estimation of reservoir liquid and gas properties from MSRKE is often needed when detailed laboratory PVT data are not available.     

Design and testing of SMA temperature-compensated cavity resonators

In this paper, we present a method for designing temperature-compensated cavity resonators using shape memory alloys (SMAs). This paper gives an expression for the temperature drift of resonant frequency, which is valid for any conductor-loaded cavity regardless of its shape. This formula, combined with a field perturbation model, is used to derive the resonant frequency of an SMA-compensated resonator subject to temperature fluctuation. Experimental results are given that confirm the feasibility of the proposed design approach. A design method is proposed for specifying SMA alloys to build the actuator. An expression is derived to accurately predict the performance of an actuator design.     

Bioactive lipids and antioxidant properties of wild Egyptian Pulicaria incise, Diplotaxis harra, and Avicennia marina

Fatty acids, sterols and tocopherols profile of Pulicaria incise, Diplotaxis harra and Avicennia marina grown wild in Egypt were investigated. Linoleic acid followed by palmitic and oleic acids were the major fatty acids in P. incise. Oleic followed by stearic were the main acids in D. harra, while palmitic followed by oleic were the major fatty acids found in A. marina. Sterol markers of P. incise were campesterol followed by stigmasterol and β-sitosterol. In D. harra β-sitosterol followed by stigmasterol and ?5-avensterol were the major sterols, while campesterol followed by β-sitosterol and ?7-avensterol were main sterols of A. marina. Tocopherols were also estimated in high levels, wherein δ-tocopherol was the main tocopherol in all plants. Antioxidant properties of methanolic extracts of the plants were compared with methanolic solution of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and ascorbic acid during thiocyanate assay. Moreover, methanolic extracts of the whole plants exhibited strong antiradical potential against DPPH radicals. Information provided by the present study is of importance for further investigations of P. incise, D. harra and A. marina and utilization of these plants as a raw material of bioactive compounds.     

Variations in tomato (Lycopersicon esculentum) cultivars grown under heat stress

Tomato (Lycopersicon esculentum Mill) is considered as important and economic agricultural crop all over the world. For improving the yield and yield attributes, varieties are often produced and evaluated under different growth condition. In the study presented morphological (growth and yield parameters), biochemical (oil, moisture content and radical scavenging activity) and molecular diversity (RAPD and ISSR) of eleven freshmarket tomato (L. esculentum) cultivars (Aledo VF, Carmeuco 201M, Castle-rock, Falkon, Money Maker, Peto 86, Red Star, Super Marmande, Super Queen, Super Strain B, and UC97–3) were analyzed under heat stress in Egypt to assist breeders in selecting heat tolerant cultivars and nutritional quality. Cultivars Aledo, Peto86 and Red Star were found to have the most vigorous growth habit, while cv. Super Queen has the most significant average fruit weight, yield/plant and total yield/m² under heat stress. For nutritional quality cv. Super marmande and cv. Aledo showed the highest oil content while cv. Aledo and cv. Money Maker showed the highest radical scavenging activities (RSA). Molecular polymorphism among cultivars was detected using two molecular markers systems, RAPD (random amplified polymorphic DNA) and ISSR (inter-simple sequence repeat), providing further facilities for molecular comparison.