Recent progress in the manufacture of alkanesulfonates: Photosulfochlorination of single-chain length (C12−C16) n-alkanes using SO2Cl2 at high conversion rates in pure phase and in the presence of solvent

Increasing concentration of sulfuryl chloride during the photosulfochlorination reaction under visible light shows that under these conditions n-alkanes react at high conversion rates instead of the conversion rate of 15% reported in the literature. This photosulfochlorination with sulfuryl chloride leads to better and more interesting results compared with those of photosulfochlorination by gas mixture. Indeed, nearly total conversion of n-alkanes, specifically n-heptane, n-dodecane, n-tetradecane, and n-hexadecane, occurred in pure phase, with a quantitative global yield, a sulfochlorination-to-chlorination molar ratio of about 1, and a relative reactivity of secondary to primary hydrogen of about 2.5, at a reaction temperature of 30°C and a reaction time of 120 min, using 2×10⁻² mol L⁻¹ of pyridine. Under these conditions, no polysulfochlorinated compounds are detected. These results are further improved using chlorobenzene as the solvent, instead of benzene. Indeed, the sulfochlorination of n-heptane at a conversion rate of 80% in the presence of chlorobenzene leads also to a quantitative reaction yield, a higher RSO₂Cl/RCl molar ratio, and, as expected, a high selectivity of secondary over primary hydrogen. Under these conditions, sulfochlorination of long-chain n-alkanes leads to the highest RSO₂Cl/RCl molar ratio for n-dodecane, n-tetradecane, and n-hexadecane belonging to detergent range, and the value of the molar ratio for these is between 1.45 and 1.7. The isomeric distribution of sulfochlorinated compounds obtained during sulfochlorination in the presence of solvent resembles that of secondary alkanesul-fonates produced by sulfoxidation reaction, whereas that obtained in pure phase has a similar conversion rate, is rich in primary isomer, and thus is different from that of classic radical reactions such as photochlorination or photosulfochlorination with gas mixture.     

Micellar Behavior of Anionic Surfactants with Sulfonate Function in Aqueous Solutions

Using different reaction conditions of photosulfochlorination of n-alkanes, various samples of anionic surfactants of sulfonates type have been obtained. Their micellar behavior was researched and the relationship between their isomeric distribution and so, their chemical structures and micellar behaviors were more thoroughly explored. Their critical micelle concentrations (CMC) were determined with surface tension measurements, the surface activities (γ_CMC) were obtained, the surface absorption amounts (Γm) and the molecular areas (Am) at the interface of air-water gained by using Gibbs’ equation. In addition, under the conditions of adding electrolyte NaCl, the critical micellar concentrations (CMCs) of two samples were also examined, and the effects of the addition of electrolyte on their micellar behaviors were studied. The experiment results show that the samples rich in secondary isomers have characteristic micellar behavior: CMC are higher, and the abilities to decrease surface tension are better, which well compared to common anionic surfactants, especially Hostapur 60, commercially available. Besides, the effects of addition of electrolyte on the micellar behaviors of the anionic surface-active agents are similar to common anionic surfactants.

Integrating RFID and WLAN for indoor positioning and IP movement detection

Location awareness in an indoor environment and wireless access to Internet applications are major research areas towards the overwhelming success of wireless and mobile communications. However, the unpredictable indoor radio propagation and handover latency due to node mobility are the main challenging issues that need to be addressed. For tackling efficiently both problems of indoor localization and handover management, we propose combining key benefits of two outstanding wireless technologies, i.e. radio frequency identification (RFID) and a wireless local area network (WLAN) infrastructure. WLANs, such as IEEE 802.11 (WiFi), are now very common in many indoor environments for providing wireless communication among WiFi-enabled devices by accessing an Access Point (infrastructure mode) or through peer to peer connections (ad hoc mode). However, the small cell size of the Access Points (APs) in a WiFi-based network drives the need for frequent handovers leading to increased latency. RFID is an emerging technology consisting of two basic components, a tag and a reader, and its main purpose is the automatic identification of tagged objects by a reader. However, in the presence of multiple readers, RFID suffers from the so-called reader collision problem, mainly due to the inability for direct communication among them. In this paper, we propose a hybrid RFID and WLAN system; the RFID technology is employed for collecting information that is used for both localization and handover management within the WLAN, whereas the WLAN itself is utilized for controlling and coordinating the RFID reading process. In our system architecture, tag IDs of a RFID tag deployment are correlated with both location and topology information in order to determine the position and predict the next subnetwork of a Mobile Node (MN) with a reader attached to its mobile device. The role of the WLAN is to coordinate the readers when accessing the RFID channel for retrieving tags?? IDs, hence compensating the persisting RFID collision problem among multiple readers. Numerical results based on extensive simulations validate the efficiency of the proposed hybrid system in providing accurate and time efficient localization and reducing the IP handover latency.     

Wireless sensor networks: a survey on recent developments and potential synergies

Wireless sensor network (WSN) has emerged as one of the most promising technologies for the future. This has been enabled by advances in technology and availability of small, inexpensive, and smart sensors resulting in cost effective and easily deployable WSNs. However, researchers must address a variety of challenges to facilitate the widespread deployment of WSN technology in real-world domains. In this survey, we give an overview of wireless sensor networks and their application domains including the challenges that should be addressed in order to push the technology further. Then we review the recent technologies and testbeds for WSNs. Finally, we identify several open research issues that need to be investigated in future. Our survey is different from existing surveys in that we focus on recent developments in wireless sensor network technologies. We review the leading research projects, standards and technologies, and platforms. Moreover, we highlight a recent phenomenon in WSN research that is to explore synergy between sensor networks and other technologies and explain how this can help sensor networks achieve their full potential. This paper intends to help new researchers entering the domain of WSNs by providing a comprehensive survey on recent developments.     

Competitive biosorption of heavy metals from aqueous solutions onto <Emphasis Type="Italic">Streptomyces rimosus</Emphasis>

The aim of this study is the simultaneous biosorption of Cd⁺² and Ni⁺² on a dead biomass, Streptomyces rimosus pretreated with NaOH (0,1 M). Kinetic tests were carried out for the binary mixture (cadmium-nickel) during 6 hours contact time to ensure that balance was reached. The amounts adsorbed at equilibrium were 22.8 mg Ni²⁺/g and 9.86 mg Cd²⁺/g biomass, respectively. The biosorption depends mainly by some parameters, such as the pH, the initial concentration of metal and the initial concentration of biomass. The isotherm of adsorption according to two models, Langmuir and Freundlich, was carried out in our study. The results of the kinetics of adsorption show that the experimental values are well represented by the kinetic model of pseudo-second order. This enables us to determine the behavior of these adsorbents with respect to a real industrial effluent.     

A First Principles Density Functional Study of Crystalline FOX‐7 Chemical Decomposition Process under External Pressure

We report on a first principles analysis of chemical decomposition reaction in a crystalline FOX‐7 (1,1‐diamino‐2,2‐dinitroethylene) molecule, which is a good candidate for insensitive energetic materials. Our calculations are based on variable‐cell shape methods under pressure, density functional theory with localized numerical orbital and pseudopotential, together with ab initio biasing molecular dynamics. The calculated crystal structure and equation of state (pressure vs. volume) up to 8 GPa agrees well with the corresponding experimental data. A chemical decomposition by intermolecular hydrogen transfer is found at higher pressure. This decomposition appears to be driven by a weakening in the chemical hardness. This suggests that the molecular HOMO and LUMO orbital energy difference is decreased when intermolecular hydrogen transfers occur, and for the FOX‐7 crystal the band gap is narrowed with increasing external pressure.     

Scene analysis indoor positioning enhancements

The emergence of innovative location-oriented services and the great advances in mobile computing and wireless networking motivated the development of positioning systems in indoor environments. However, despite the benefits from location awareness within a building, the implicating indoor characteristics and increased user mobility impeded the implementation of accurate and time-efficient indoor localizers. In this paper, we consider the case of indoor positioning based on the correlation between location and signal intensity of the received Wi-Fi signals. This is due to the wide availability of WLAN infrastructure and the ease of obtaining such signal strength (SS) measurements by standard 802.11 cards. With our focus on the radio scene analysis (or fingerprinting) positioning method, we study both deterministic and probabilistic schemes. We then describe techniques to improve their accuracy without increasing considerably the processing time and hardware requirements of the system. More precisely, we first propose considering orientation information and simple SS sample processing during the training of the system or the entire localization process. For dealing with the expanded search space after adding orientation-sensitive information, we suggest a hierarchical pattern matching method during the real-time localization phase. Numerical results based on real experimental measurements demonstrated a noticeable performance enhancement, especially for the deterministic case which has additionally the advantage of being less complex compared to the probabilistic one.     

Experimental analysis on a novel low-temperature vacuum drying with induced nucleation technique for dewatering stingless bees honey

Honey spoilage is a major problem in storing stingless bee honey. A new method of honey dewatering was developed using a low-temperature vacuum drying with induced nucleation technique. The research’s objective is to investigate the performance of this method in reducing honey’s water content. Two different dewatering temperatures were applied until honey’s water content reached below 20%. The honey’s chemical compound before–after dewatering from one of the samples was tested using nuclear magnetic resonance (NMR) analysis. The dewatering rate improves significantly with higher temperature. The NMR analysis result found no changes in chemical compound before–after experiment except for ethanol.     

Development of antipeptide enzyme‐linked immunosorbent assay for determination of gelatin in confectionery products

The gelatin sources have become a controversial issue with regard to religious and health concern. Thus, the aims of this study were to develop and evaluate the efficiency of polyclonal antibodies against peptide immunogen of collagen α2 (I) chain for determination of gelatin sources in confectionery products by competitive indirect enzyme‐linked immunosorbent assay (ELISA). Collagen α2 (I) chain protein showed resistance against heat treatment and detectable in certain commercial products when analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE). The established ELISA exhibited low cross‐reactivity to fish and chicken gelatin. The IC₅₀ value was 0.39 μg mL^?1, and the limit of detection (IC₁₀) was 0.05 μg mL^?1. There were no false‐positive results from forty‐eight commercially processed products. The present method is useful for determination of gelatin in confectionery products.     

A new policy‐aware terminal for QoS,AAA and mobility management

Policy‐based management has been widely studied in recent years. The Internet Engineering Task Force (IETF) has recently introduced the policy‐based networking as a means of managing IP networks according to the new constraints defined in the network, such as the guarantee of the quality of service (QoS). Network management based on policies, is modelled as a state machine, which moves from one state to another according to the enforced policy. The IETF policy‐based networking is defined for application to network nodes. However, some recent work suggests extending the policy‐based networking to the end‐user terminals. In this paper, we present an analysis of such an extension and we propose some possible solutions to support new policy‐aware terminals. In addition, we present AAA, QoS and mobility management that user such a policy‐aware terminals. Copyright © 2004 John Wiley & Sons, Ltd.