Synthesis and characterization of PMMA composites activated with starch for immobilization of L‐asparaginase

Poly (methyl methacrylate) (PMMA)–starch composites were prepared by emulsion polymerization technique for L‐asparaginase (L‐ASNase) immobilization as highly activated support. The hydroxide groups on the prepared composites offer a very simple, mild and firm combination for enzyme immobilization. The pure PMMA and PMMA‐starch composites were characterized as structural, thermal and morphological. PMMA‐starch composites were found to have better thermal stability and more hydrophilic character than pure PMMA. L‐ASNase was immobilized onto PMMA‐starch composites contained the different ratio of starch (1, 3, 5, and 10 wt %). Immobilized L‐ASNase showed better performance as compared to the native enzyme in terms of thermal stability and pH. K_m value of immobilized enzyme decreased approximately eightfold compared with the native enzyme. In addition to, immobilized L‐ASNase was found to retain 60% of activity after 1‐month storage period at 4 °C. Therefore, PMMA‐starch composites can be provided more advantageous in terms of enzymatic affinity, thermal, pH and storage stability as L‐ASNase immobilization matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43421.     

Coagulation of turbid water and softening of hardwater with Moringa oleifera seeds

In this study, the effects of 5 process variables on softening hardwater and coagulation of surface water with a M. oleifera seed extract were investigated. Multiple regression analysis showed a strong correlation (R² (adj.) = 0.99 between M. oleifera seed dosage and the initial hardness of synthetic hardwater. Since M. oleifera is known to be a polyelectrolyte, the softening mechanism is likely to be adsorption. An adsorption isotherm developed was approximately linear and conformed to the Langmuir type. For the coagulation studies, the water samples were from three rivers in Kano, Nigeria over a three month period during the rainy season (June‐August 1994). The turbidity of the water sample varied from 105–350 NTU. When used as primary coagulant, M. oleifera was able to achieve up to 99% turbidity removal for two of the water samples at the optimum dosage of 250 mg/l. For the third water sample, the optimum dosage was 450 mg/l which is assumed to be due the high value of the colour of the water. Saving in alum usage of up to 40% was achievable when M. oleifera was used in conjunction with alum.     

Automated adaptive 3D forming simulation processes

In this study, an automated adaptive mesh control scheme, based on local mesh modifications, is developed for the finite element simulations of 3D metal-forming processes. Error indicators are used to control the mesh discretization errors, and an h-adaptive procedure is conducted. The mesh size field used in the h-adaptive procedure is processed to control the discretization and geometric approximation errors of the evolving workpiece mesh. Industrial problems are investigated to demonstrate the capabilities of the developed scheme.     

A practical solid sampling method for the determination of lead in chewing gum by electrothermal atomic absorption spectrometry

In this study, the lead concentrations of chewing gum samples having different compositions were determined by solid sampling electrothermal atomic absorption spectrometry. In order to optimise the experimental conditions, the effects of pyrolysis temperature, atomization temperature, sample amount and sample thermal pre-treatment, on the analyte sensitivity were investigated. The samples were ashed at 400 °C for 2 h prior to directly determined by SS-ETAAS applying 600 °C of pyrolysis and 1600 °C of atomization temperatures without to add a modifier, acid and/or surfactant. The relationship between sample mass and integrated absorbance was linear up to 1.2 mg of sample; for higher sample mass the relationship was no longer linear, irrespective of the lead content. In addition, the thermally treated chewing gum samples were digested using concentrated HNO₃. The lead concentrations found by the two methods in 27 different kinds of samples were not significantly different at 95% confidence level. The proposed solid sampling technique was fast, simple, the risks of contamination and analyte loss were low. Detection limit (3σ) for lead was 0.017 ng/g.     

Elastic and shear moduli of coal measure rocks derived from basic well logs using fractal statistics and radial basis functions

Gamma ray, density, sonic and core logs obtained from two boreholes drilled over a longwall panel in Southwestern (SW) Pennsylvania were analyzed for formation boundaries, log-derived porosities and densities and for rock elastic properties from sonic transit times. Gamma ray (GR) and density logs (DL) were analyzed using univariate statistical techniques and fractal statistics for similarity and ordering of the log data in depth. A Fourier transformation with low-pass filter was used as a noise elimination (filtering) technique from the original logs. Filtered data was tested using basic univariate and fractal statistics, rescaled range (R/S) and power spectrum (PS) analysis to compare the information characteristics of the filtered logs with the original data. The randomness of log data in depth was analyzed for fractional Gaussian noise (fGn) or fractional Brownian motion (fBm) character.A new prediction technique using radial basis function (RBF) networks was developed to calculate shear and Young's moduli of the formations when sonic logs are not available. For this approach, the filtered logs were used as input to an RBF based upon a combination of supervised and unsupervised learning. The network was trained and tested using rock elastic properties calculated from the sonic log of one of the boreholes. The network was used to predict the elastic and shear moduli of the coal-measure rocks over a longwall coal mine in SW Pennsylvania. This approach demonstrated that it could be used for prediction of elastic and shear moduli of coal-measure rocks with reasonable accuracy.     

Degasification system selection for US longwall mines using an expert classification system

Methane emissions from the active face areas and from the fractured formations overlying the mined coalbed can affect safety and productivity in longwall mines. Since ventilation alone may not be sufficient to control the methane levels on a longwall operation, gob vent boreholes (GVB), horizontal and vertical drainage boreholes, and their combinations are drilled and used as supplementary methane control measures in many mines. However, in most cases, the types of degasification wellbores chosen are decided based on previous experiences without analyzing the different factors that may affect this decision.This study describes the development of an expert classification system used as a decision tool. It was built using a multilayer perceptron (MLP) type artificial neural network (ANN) structure. The ANN was trained using different geographical locations, longwall operation parameters, and coalbed characteristics as input and was tested to classify the output into four different selections, which are actual degasification designs that US longwall mines utilize. The ANN network selected no degasification, GVB, horizontal and GVB, and horizontal, vertical and GVB options with high accuracy. The results suggest that the model can be used as a decision tool for degasification system selection using site- and mine-specific conditions. Such a model can also be used as a screening tool to decide which degasification design should be investigated in detail with more complex numerical techniques.     

Rubber effect on metallic dampers used on the supports of steel cross members

There are many strengthening methods made with steel cross members for strengthening the structures with inadequate earthquake behavior. This type of strengthening methods is also effective in buckling of the cross members in the behavior of the structural frames. This buckling may cause partial or complete collapse of the structure. Thus, it is quite important to prevent and limit the formation of buckling in steel crosses. At the TEC 2018, the insulation unit is defined as the elements that can exhibit flexible behavior on the horizontal direction and rigid behavior on the vertical direction under the effect of earthquake loads. The basic principle of using insulation units is that these members can dissipate energy in the carrier system. The originality of this study is to experimentally investigate the damper behavior created by using cylindrical rubber wedges, which can be easily found in the automotive industry, in combination with steel plates and bolts. In this experimental study, the contribution of seismic insulators to the structural element to be strengthened was investigated. The insulators used in this study are considered by analogy with lead-core rubber insulators. As such seismic lead-core rubber insulators move under the influence of lateral loads, the lead core inside makes plastic deformation, thus increasing the damping rate. In this insulator study, it is aimed to use U plates or bolts instead of lead core. While vertical loads are covered by rubber support, horizontal loads will be damped due to plastic deformation of U plates or bolts. The five types of seismic dampers were used as 10 B-type rubber wedge mounted damper (SR), 2 U-type steel plates damper (SP), 10 M6 steel bolted damper (SB), 2 U-type steel plates and 10 B-type rubber wedge mounted damper (SPR), 10 M6 steel bolted, and 10 C-type rubber wedge mounted damper (SBR). These specimens were tested under lateral loading and constant vertical loading. The results obtained at the end of the tests shall be compared considering the strength, stiffness, and dissipated energy capacities of the specimens.     

A Novel Cross-layer Routing Protocol for Increasing Packet Transfer Reliability in Mobile Sensor Networks

In mobile sensor networks (MSNs), sensor data is generally transferred via mobile sensor nodes by multi-hop fashion. Because of the mobility of the nodes in the network, the efficient routing protocols are needed to ensure end-to-end route reliability while incurring minimal power consumption and packet delay. In this study, we developed a new routing protocol to meet these requirements for MSNs based on a cross-layer interaction among five reference layers (application, transport, network, MAC and physical). The proposed protocol primarily exploits the idea of interaction among these five layers all-in-one protocol. Its primary goals are (i) to discover the most reliable route in network, (ii) to sustain the route reliability and (iii) to be energy efficient and delay aware. It has been designed, modeled and simulated by using OPNET Modeler simulation software. The simulation results of the proposed protocol have been compared to three well known routing protocols (i.e., AODV, Leach-Mobile, CBR-Mobile). According to the obtained results, the proposed protocol outperforms its counterparts in terms of route reliability and end-to-end delay performances.     

Performance analysis of new-design solar air collectors for drying applications

This paper presents a performance analysis of four types of air heating flat plate solar collectors: a finned collector with an angle of 75°, a finned collector with an angle of 70°, a collector with tubes, and a base collector. In this study, the first and second laws of efficiencies were determined for the collectors and comparisons were made among them. The results showed that the efficiency depends on the solar radiation and the construction of the solar air collectors. The temperature rise varied almost linearly with the incident radiation. The first law of efficiency changed between 26% and 80% for collector-I, between 26% and 42% for collector-II, between 70% and 60% for collector-III, and between 26% and 64% for collector-IV. The values of second law efficiency varied from 0.27 to 0.64 for all collectors? The highest collector efficiency and air temperature rise were achieved by the finned collector with angle of 75°, whereas the lowest values were obtained for the base collector. The effectiveness order of the collectors was determined as the finned collector with angle of 75°, the finned collector with angle of 70°, the collector with tubes, and the base collector.     

Optimizing physical parameters affecting coagulation of turbid water with Morninga oleifera seeds

Moringa oleifera is a plant coagulant and coagulant aid which has potential for use on a large scale for treatment of turbid waters in tropical developing countries. This paper presents results of optimization studies on physical factors including rapid mix velocity gradient and time, slow mix velocity gradient and time, and dosage of M. oleifera for low, medium and high raw water turbidities (50–750 NTU). Regression analysis was also carried out to study the effect of multiple factor interaction in the coagulation of turbid water with M. oleifera. This was carried out using the results of experimental runs involving varying initial turbidity, M. oleifera dosage, rapid mix velocity gradient, slow mix velocity gradient, and slow mix time.