Removal of limonin bitterness by treatment of ion exchange and adsorbent resins

This study, the selective removal of limonin bitterness from Washington navel orange juice by batch adsorption to the Amberlite XAD-16HP and Dowex Optipore L285 was investigated and the determination of some compositional changes that occurred with orange juices debittering using adsorption resins were the primary focus. Amberlite XAD-16HP and Dowex Optipore L285 have been successfully used to reduce bitterness to acceptable levels in Washington navel orange juices. Amberlite XAD-16HP does not have any important negative effects on the quality characteristics of orange juices. However, Dowex Optipore L285 reduces the titratable acidity (TA) in the orange juices and so increases the content of soluble solids contents (SSC), pH value, and ratio accordingly.     

Mercury levels in cord blood and meconium of healthy newborns and venous blood of their mothers: clinical, prospective cohort study

OBJECTIVES: The purpose of this study is to investigate the chronic mercury intoxication in pregnant women and newborns living in Istanbul, Turkey. METHODS: The research was carried out as a prospective with 143 pregnant women and their newborns. Venous blood from the mother, cord blood from the neonate, and meconium were collected for mercury analysis. Frequency of fish and vegetable-eating and the number of teeth filled were investigated. Analyses were made in cold vapor Atomic Absorption Spectrophotometer (AAS, microg/L). RESULTS: Mercury levels were 0.38+/-0.5 microg/L (0-2.34) in venous blood of pregnant women, 0.50+/-0.64 microg/L (0-2.36) in umbilical cord blood and 9.45+/-13.8 microg/g (0-66.5) in meconium. Maternal blood mercury level was lower than the known toxic limit for humans (EPA, 5 microg/L). Mercury levels of the maternal venous blood were significantly correlated with umbilical cord blood. The primary risk factors affecting mercury levels were eating fishmeals more than twice a week and having filled teeth more than five. The fact that the mother had a regular vegetable diet everyday reduced the mercury levels. Increased levels of mercury in the mother and umbilical cord blood could lead to retarded newborns' weight and height. CONCLUSION: Pregnant women living in Istanbul may be not under the risk of chronic mercury intoxication. Fish consumption more than twice per week and tooth-filling of mother more than five may increase mercury level. On the contrary, regular diet rich in vegetable decreases the mercury level.     

An expert system approach for die and mold making operations

In the modern manufacturing of sophisticated parts with 3D sculptured surfaces, die and mold making operations are the most widely used machining processes to remove unwanted material. To manufacture a die or a mold, many different cutting tools are involved, from deep hole drills to the smallest ball nose end mills. Since the specification of each tool is very different from each other, each mold or die is specific with their complicated shapes and many machining rules exist to consider, a great deal of expertise is needed in planning the machining operations. An expert system (DieEX) developed for this purpose is described in the present work. The geometry and the material of the workpiece, tool material, tool condition and operation type are considered as input values and various recommendations about the tool type, tool specifications, work holding method, type of milling operation, direction of feed and offset values are provided.     

User QoE Influenced Spectrum Trade,Resource Allocation,and Network Selection

In future wireless networks, we envision more dynamic telecommunication paradigm, where the dynamics may be translated into dynamic service offerings and user profiles etc. We further expect that the wireless communication market will be influenced when the user-centric network selection vision is realized. By the user-centric network selection vision, we mean that users will be free to select any available network operator or service provider on short term contractual basis. This dictates that operators will compete for their share of a common user pool on much smaller time quanta when compared with the current long term user contacts with the operators. One intuitive strategy of operators will be to incentivize users by offering different QoS and service price offers. As the operators’ offers are influenced by their incurring costs. This necessitates to study the market behavior at different levels and investigate the operator and user behavior at these level. In this paper, we categorize and position the communication players and model the interaction between players at different levels. We introduce the learning aspects in the interaction and investigate the equilibrium strategies of involved stake-holders i.e., users and operators. We also model the utility functions of all the involved stake-holders. We also examine the risk-sensitive utility functions in order to cover both risk-seeking and risk-averse in the user QoEs. We implement the user-centric approach and compare it against our proposed network-centric resource utilization and call blocking.     

A study on fusion and rheological behaviors of PVC/SiO2 microcomposites and nanocomposites: The effects of SiO2 particle size

In this study, poly(vinyl chloride) (PVC) and silica (SiO₂) microcomposites and nanocomposites were prepared by melt mixing in a Haake torque rheometer. The fusion and rheological behaviors of PVC/SiO₂ composites were evaluated by means of torque data recorded during processing to investigate the influence of the SiO₂ particle size on these behaviors. It was found that the fusion time and the fusion temperature decreased with the decreasing of SiO₂ particle size, whereas the fusion torque increased with the decreasing of particle size. The PVC/Si‐25‐nm nanocomposite (PVC including the 25 nm of SiO₂) showed the highest apparent viscosity among the PVC/SiO₂ microcomposites and nanocomposites prepared in this study. Scanning electron microscopy results demonstrated that some aggregates, whose sizes about 60–90 nm, were formed when the 25 nm of SiO₂ was used as filler. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effect of 2% chlorhexidine gluconate cavity disinfectant on microtensile bond strength of tooth-coloured restorative materials to sound and caries-affected dentin

This study evaluated the effect of 2% chlorhexidine gluconate-based cavity disinfectant (CHX) on the microtensile bond strength (μTBS) of glass ionomer, resin-modified glass ionomer and packable resin composite to sound and caries-affected dentin. Sound and occlusal caries-affected human third molars (N?=?36, n?=?3 per group) were randomly divided into three experimental groups to receive one of the following restorative materials. (a) Glass ionomer (Ketac Molar, 3 M ESPE; GI), (b) resin-modified glass ionomer (Vitremer, 3 M ESPE; RMGI) and (c) packable resin composite (Surefil, Dentsply; PRC) with a bonding agent (Prime Bond NT, Dentsply De Trey). Caries was removed using a caries-detecting dye (Caries Detector, Kuraray Medical Ltd.) and flat dentin surfaces were achieved by finishing up to 1200-grit silicon carbide abrasive. Half of the teeth in each group received 2% CHX (Consepsis, Ultradent). Dentin surfaces were built-up with the respective materials incrementally and were sectioned with a slow-speed saw into multiple beams. The beams were subjected to μTBS test (0.5 mm/min) in a Universal Testing Machine. The data were analysed using two-way analysis of variance and Tukey’s tests. For each restorative material, μTBS results were not affected by the application of CHX (p?>?0.05) on both sound and caries-affected dentin (p?>?0.05). PRC in combination with the corresponding bonding agent showed significantly higher results (p?<?0.05) than those of GI and RMGI, on sound and caries-affected teeth, respectively. Cohesive failure in dentin was not observed in any of the groups. The use of 2% chlorhexidine-based cavity disinfectant did not impair the adhesion of the restorative materials tested to either sound or caries-affected dentin.     

Low Temperature Initiation by 3-Mercaptopropionic Acid-Ce(IV) or -KMnO4 Redox System for Polymerization of Acrylamide Monomer

Polymerization of acrylamide monomer was performed at low temperatures using 3-mercaptopropionic acid-cerium(IV) sulfate and 3-mercaptopropionic acid-KMnO₄ redox systems in acid aqueous medium. Water soluble polyacrylamides containing 3-mercaptopropionic acid end groups were synthesized. The effects of mole ratio of acrylamide to initiator(n_MSA= n_Ce(IV)), polymerization time, temperature, and concentration of sulfuric acid on the yield and molecular weight of polymer were investigated. The decrease in the mole ratio of acrylamide/Ce(IV) at constant monomer concentration resulted in an increase in the yield but a decrease in molecular weight of polymer. The increase of reaction temperature from 20° to 70°C resulted in a decrease in the yield but indicated generally a constant value for the molecular weight of polymer. With increasing of polymerization time, the yield and molecular weight of polymer did not change mainly. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions, respectively in the polymerization reaction. The existence of Ce(III) ion bonded to polymer was investigated by UV-visible spectrometry and fluorescence measurements. The amount of Mn(II) that is incorporated to the polymer was determined using graphite furnace atomic absorption spectrometry. The mechanism of this phenomenon is discussed.     

Prediction of Channel Utilization with Artificial Neural Networks Model in Mac Layer in Wireless Local Area Networks

Wireless Personal Communications - The use of channels in WLANs affects data communication. RTS Fragmentation Threshold (RTSFT), Fragmentation Threshold (FT), and Buffer Size (BS) input values;...     

Development a new mutation operator to solve the Traveling Salesman Problem by aid of Genetic Algorithms

In this study, a new mutation operator has been developed to increase Genetic Algorithm (GA) performance to find the shortest distance in the known Traveling Salesman Problem (TSP). We called this method as Greedy Sub Tour Mutation (GSTM). There exist two different greedy search methods and a component that provides a distortion in this new operator. The developed GSTM operator was tested with simple GA mutation operators in 14 different TSP examples selected from TSPLIB. The application of this GSTM operator gives much more effective results regarding to the best and average error values. The GSTM operator used with simple GAs decreases the best error values according to the other mutation operators with the ratio of between 74.24% and 88.32% and average error values between 59.42% and 79.51%.     

A Computational Investigation of the Thermohydraulics of an EGS Project

A numerical analysis of the thermohydraulics of an enhanced geothermal system project is presented. The rock structures are modelled as porous medium, based on the computationally obtained hydraulic fracturing data of other authors. The influence of the domain size, grid resolution, temporal resolution and the discretization scheme is assessed to obtain a highly accurate numerical solution under the prevailing modelling assumptions. Based on the numerical model, different production scenarios are investigated and discussed. The relative positioning of the injection and production ports is also analyzed. It is shown that there is a considerable potential for optimizing the production rate and the port configuration to obtain the most favorable results for the production temperature, investment costs and operation costs.