Dextran–rare earth ion interactions. II. Solid‐state characteristics

The solid‐state characteristics of dextran complexes precipitated from aqueous solutions with three different light‐lanthanoid cations (La³⁺, Ce³⁺, and Nd³⁺) were investigated by spectroscopic and thermal methods. Spectroscopic characterization was realized by the comparative interpretation of the FTIR spectra, and the complexes were found to involve both ligating water and dextran through its O(2) and O(3) atoms. Remarkable spectral changes were noted, particularly with La³⁺, which parallels the previous solution studies. The order of La³⁺ > Ce³⁺ > Nd³⁺ was determined to display the tendency of the Ln³⁺ ion in favor of dextran throughout the competition between water and dextran. The thermal stabilities of the complexes were examined by thermogravimetry (TG), differential TG, and DSC methods. The decomposition steps and temperatures were assigned with respect to the lanthanoid ions used. The TG and DSC results indicated that the complexes are less stable thermally than dextran itself with increasing thermal stabilities in the order of La³⁺ < Ce³⁺ < Nd³⁺ in their anhydrous states. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2168–2174, 2002     

Joining polyhedral objects using implicitly defined surfaces

Published online: 2 October 2001     

A smart manufacturing adoption framework for SMEs

Smart Manufacturing (SM) a revolutionary paradigm that aims to improve production systems’ performance in terms of quality, time, cost, and flexibility, as well as human and machine decision-making capabilities. Most large enterprises have already taken first steps towards adopting SM. Small and Medium-sized Enterprises (SMEs) on the other hand, are struggling with developing a SM adoption roadmap. Our research builds on the real and perceived needs and challenges faced by manufacturing SMEs and advances the field by developing and evaluating an SME-specific ‘SM adoption framework’. We have employed a multiple case study approach to acknowledge the lessons learned by selected early-adopter SMEs that have recently implemented and deployed SM tools and practices. We propose an SM adoption framework with five vital steps that SMEs interested in SM should follow: (i) identify manufacturing data available within the SME, (ii) readiness assessment of the SME data-hierarchy steps, (iii) developing SM awareness of SME leadership and staff, (iv) develop a SM tailored vision for the SMEs, and (v) identify appropriate SM tools and practices necessary to realise the tailored SM vision. Moreover, the results of the case study analysis enabled us to formulate many generalisations.     

Neutron Reflectivity and Performance of Polyamide Nanofilms for Water Desalination

The structure and hydration of polyamide (PA) membranes are investigated with a combination of neutron and X‐ray reflectivity, and their performance is benchmarked in reverse osmosis water desalination. PA membranes are synthesized by the interfacial polymerization of m‐phenylenediamine (MPD) and trimesoyl chloride (TMC), varying systematically reaction time, concentration, and stoichiometry, to yield large‐area exceptionally planar films of ≈10 nm thickness. Reflectivity is employed to precisely determine membrane thickness and roughness, as well as the (TMC/MPD) concentration profile, and response to hydration in the vapor phase. PA film thickness is found to increase linearly with reaction time, albeit with a nonzero intercept, and the composition cross‐sectional profile is found to be uniform, at the conditions investigated. Vapor hydration with H₂O and D₂O from 0 to 100% relative humidity results in considerable swelling (up to 20%), but also yields uniform cross‐sectional profiles. The resulting film thickness is found to be predominantly set by the MPD concentration, while TMC regulates water uptake. A favorable correlation is found between higher swelling and water uptake with permeance. The data provide quantitative insight into the film formation mechanisms and correlate reaction conditions, cross‐sectional nanostructure, and performance of the PA active layer in RO membranes for desalination.     

Acrylamide and Potential Risk of Diabetes Mellitus: Effects on Human Population,Glucose Metabolism and Beta-Cell Toxicity

Diabetes mellitus is a frequent endocrine disorder characterized by hyperglycemia. Acrylamide (AA) is food contaminant formed during the high-temperature processing of food rich in carbohydrates and low in proteins. Recent human epidemiological studies have shown a potential association between AA exposure and the prevalence of diabetes in the general population. In male rats, AA treatment promoted pancreatic islet remodeling, which was determined by alpha-cell expansion and beta-cell reduction, while in female rats AA caused hyperglycemia and histopathological changes in pancreatic islets. In vitro and in vivo rodent model systems have revealed that AA induces oxidative stress in beta cells and that AA impairs glucose metabolism and the insulin signaling pathway. Animal studies have shown that diabetic rodents are more sensitive to acrylamide and that AA aggravates the diabetic state. In this review, we provide an overview of human epidemiological studies that examined the relation between AA exposure and glucose disorders. In addition, the effects of AA treatment on pancreatic islet structure, beta-cell function and glucose metabolism in animal models are comprehensively analyzed with an emphasis on sex-related responses. Furthermore, oxidative stress as a putative mechanism of AA-induced toxicity in beta cells is explored. Finally, we discuss the effects of AA on diabetics in a rodent model system.     

Efficient Multicast Congestion Control

Now day’s computer network is an essential part of our life. Day by day, there is a high increment in the uses of computer network applications such email, bloggers, internet group, forums, conference, youtube and online TV. The exponential increment in video applications traffic, there increases challenges of computer network and it faces various problems like shortage of memory, link failure, slow processor, time out etc. These problems may lead to network congestion. Multicast is efficient system which handles the video traffic but it also suffers with congestion problem due to design vulnerability. Many researchers are working in this burning issue and they provided various solutions such as source based, receiver based and hybrid one. In this paper, we propose an efficient multicast congestion control approach which suggests the efficient joining, leaving operation based on adaptive throughput. The simulated results show that proposed scheme provides better throughput at various parameters.     

Experimental investigation of the role of a microporous layer on the water transport and performance of a PEM fuel cell

A highly reliable experimental system that consistently closed the overall water balance to within 5% was developed to study the role of a microporous layer (MPL), attached to carbon paper porous transport layer (PTL), on the water transport and performance of a standard 100 cm² active area PEM fuel cell. Various combinations of cells were built and tested with PTLs at the electrodes using either carbon fibre paper with a MPL (SGL 10BB) or carbon fibre paper without a MPL (SGL 10BA). The net water drag coefficient at three current densities (0.3, 0.5 and 0.7 A cm⁻²) for two combinations of anode/cathode relative humidity (60/100% and 100/60%) and stoichiometric ratios of H₂/air (1.4/3 and 1.4/2) was determined from water balance measurements. The addition of a MPL to the carbon fibre paper PTL at the cathode did not cause a statistically significant change to the overall drag coefficient although there was a significant improvement to the fuel cell performance and durability when a MPL was used at the cathode. The presence of a MPL on either electrode or on both electrodes also exhibited similar performance compared to when the MPL was placed at the cathode. These results indicate that the presence of MPL indeed improves the cell performance although it does not affect the net water drag coefficient. The correlation between cell performance and global water transport cannot be ascertained and warrants further experimental investigation.     

Tailored Ce- and Zr-doped Ni/hydrotalcite materials for superior sorption-enhanced steam methane reforming

Multi-functional hybrid materials are attractive for producing high-purity hydrogen (H₂) via catalytic steam reforming coupled with low temperature adsorptive separation of CO₂. In this work, modified Ni/hydrotalcite-like (HTlc) hybrid materials promoted with Ce and Zr species were synthesized and applied for the sorption-enhanced steam methane reforming process (or SESMR). The promotion with Ce and Zr resulted in strongly basic sites for CO₂ adsorption, and hence, improved H₂ production. Especially, the Ce-promoted hybrid material (Ce-HM1) exhibited the highest adsorption capacity (1.41 mol CO₂/kg sorbent), producing 97.1 mol% H₂ at T = 723 K, P = 0.1 MPa, S/C = 4.5 mol/mol and gas hourly space velocity or GHSV = 3600 mL/(g h); the breakthrough time was 1 h. High surface area and basicity of the promoted materials inhibited coke formation and undesired reactions. In addition to the improved catalytic activity and adsorption characteristics, these materials were stable and easily regenerable. Multi-cycle durability tests revealed that both the promoted materials Ce-HM1 and Zr-HM1 remained stable for up to 13 and 17 cycles. In contrast, the unpromoted hybrid material (HM1) was stable for 9 cycles only. Thus, promotion with Ce and Zr was beneficial for producing pure H₂.     

An Efficient Compressive Sensing Routing Scheme for Internet of Things Based Wireless Sensor Networks

Wireless Personal Communications - Internet of Things (IoT) integrates diverse types of sensors, mobiles and other technologies to physical world and IoT technology is used in a wide range of...