Guest Editorial

Multimedia Tools and Applications -     

A flexible UMTS/WLAN architecture for improved network performance

Current trends in cellular telecommunications suggest the incorporation of Wireless Local Area Networks (WLANs) as supplementary access technologies into the existing cellular infrastructure. Overlay network architectures are expected to improve both service provision and resource utilization under the condition that sophisticated architectural options are followed. Many proposals suggest that all active connections be handled through the same access network technology. However, this is not believed to be efficient in a heterogeneous environment. Therefore, a mechanism that allows each connection of a terminal to be served by different radio access technology is introduced. Based on a tight coupling architecture for interworking between Universal Mobile Telecommunications System (UMTS) and WLANs, the proposed scheme combines a sophisticated decision mechanism with flexible connection management in a way that ensures seamless service continuity during handover. The performance of the system is evaluated using a detailed simulation model and compared against existing architectures. Simulation results indicate an improvement in parameters such as connection and handover blocking probabilities, which justifies the enhancement in the overall usage of network resources when connections are handled separately.     

OmniStore: Automating data management in a personal system comprising several portable devices

The ever growing amount of data generated and consumed on the move using portable devices gives rise to serious data management issues. The fact that each person may own and is likely to carry several such devices further aggravates this problem. On the other hand, new opportunities for achieving cleverer device interaction emerge due to the increased wireless networking capabilities of wearable and portable devices. This paper introduces OmniStore, a system that combines portable devices and infrastructure-based services to relieve the user from explicit and time consuming file management tasks. Our approach is to let devices communicate with each other as well as with a repository service, in an opportunistic and asynchronous fashion, to perform a variety of file movement and copying actions behind the scenes, which would have typically required considerable explicit user interaction.     

Quantitative method for the profiling of the endocannabinoid metabolome by LC-atmospheric pressure chemical ionization-MS

The endocannabinoid system's biological significance continues to grow as novel endocannabinoid metabolites are discovered. Accordingly, a myopic view of the system that focuses solely on one or two endocannabinoids, such as anandamide or 2-arachidonoyl glycerol, is insufficient to describe the biological responses to perturbations of the system. Rather, the endocannabinoid metabolome as a whole must be analyzed. The work described here is based on liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry. This method has been validated to quantify, in a single chromatographic run, the levels of 15 known or suspected metabolites of the endocannabinoid system in the rat brain and is applicable to other biological matrixes. We have obtained an endocannabinoid profile specifically for the frontal cortex of the rat brain and have determined anandamide level differences following the administration of the fatty acid amide hydrolase inhibitor AM374.     

Designed spiro-bicyclic analogues targeting the ribosomal decoding center

The bacterial ribosome represents the confirmed biological target for many known antibiotics that interfere with bacterial protein synthesis. Aminoglycosides represent a lead paradigm in RNA molecular recognition and constitute ideal starting points for the design and synthesis of novel RNA binders. Previous rational design approaches of RNA-targeting small molecules have been mainly concentrated on direct functionalization of aminoglycosidic substructures. Herein, we successfully designed and synthesized rigid spirocyclic scaffolds locked in a predicted ribosome-bound "bioactive" conformation. These analogues are able to mimic many of the interactions of the natural products for the A-site, as proven by their obtained binding affinities. The development of an optimized approach for their synthesis and their potential to inhibit protein production in vitro are presented. Our results could be further utilized for the development of analogues with improved antibiotic profiles.     

Ezetimibe Treatment Lowers Indicators of Oxidative Stress in Hypercholesterolemic Subjects with High Oxidative Stress

Ezetimibe effectively reduces low-density lipoprotein cholesterol (LDL-C). In this study, we tested the hypothesis that ezetimibe monotherapy may also decrease markers of oxidative stress in subjects with hypercholesterolemia. Subjects with hypercholesterolemia and no evidence of cardiovascular disease were randomly allocated to open-label ezetimibe monotherapy 10 mg/day (EZT group) or therapeutic lifestyle changes (TLC group). At baseline and 12 weeks post-treatment serum lipoprotein and apolipoprotein levels as well as oxidative stress parameters, including oxidized LDL (ox-LDL), 8-isoprostanes (8-epiPGF2a) and reactive oxygen metabolites (d-ROMs) levels, were blindly determined. A total of 60 patients were included; 30 in each group. Despite a significant decrease in ox-LDL levels (by 20.8%, p < 0.001 vs. baseline; p < 0.001 vs. TLC group) in the EZT group no change in the ratio ox-LDL to LDL-C was noticed following ezetimibe treatment. No significant change in 8-epiPGF2a and d-ROMs levels was observed in the EZT group. Of note, a significant decrease in 8-epiPGF2a and d-ROMs levels (by 20.4% and 18.2%, respectively, p < 0.01 vs. baseline for both), was noted among patients in the EZT group who exhibited ‘high oxidative stress’ at baseline. No change in any of oxidative stress parameters was noted in the TLC group. Ezetimibe may decrease markers of oxidative stress in hypercholesterolemic subjects. This benefit may be more profound among patients who exhibit ‘high oxidative stress’ at baseline.     

发展小型清洁发展机制可再生能源项目的简化程序

各种灵活的京都机制已经作为以市场为基础的解决气候变化的方法发展起来了。更具体的说，清洁发展机制(CDM)是指一个工业化国家通过在发展中国家实施减排项目(特别是可再生能源项目)来实现其部分减排义务的一种灵活机制。目前发展中国家没有承担减少温室气体排放方面的义务。介绍了京都议定书的清洁发展机制促进可再生能源(RES)投资的能力，并且分析了在CDM机制下小型项目的发展潜力。     

Electrochemical enhancement of solar photocatalysis: degradation of endocrine disruptor bisphenol-A on Ti/TiO2 films

The photoelectrocatalytic oxidation over immobilized Ti/TiO₂ films in the presence of simulated solar light was investigated for the degradation of bisphenol-A (BPA) in water. The catalyst, consisting of 75:25 anatase:rutile, was prepared by a sol-gel method and characterized by cyclic voltammetry, X-ray diffraction and scanning electron microscopy. Experiments were conducted to assess the effect of applied current (0.02-0.32 mA/cm²), TiO₂ loading (1.3-9.2 mg), BPA concentration (120-820 μg/L), initial solution pH (1 and 7.5) and the aqueous matrix (pure water and treated effluent) on BPA photoelectrocatalytic degradation which was monitored by high performance liquid chromatography equipped with a fluorescence detector. The reaction was favored at anodic currents up to 0.04 mA/cm² and lower substrate concentrations, but it was hindered by the presence of residual organic matter and radical scavengers (e.g. bicarbonates) in treated effluents. Moreover, a pseudo-first order kinetic model could fit the experimental data well with the apparent reaction constant taking values between 2.9 and 32.4 10⁻³/min. The degradation of BPA by pure photocatalysis or electrochemical oxidation alone was also studied leading to partial substrate removal. In all cases, the contribution of applied potential to photocatalytic degradation was synergistic with the photocatalytic efficiency increasing between 24% and 97% possibly due to a more efficient separation and utilization of the photogenerated charge carriers. The effect of photoelectrocatalysis on the ecotoxic and estrogenic properties of BPA was also evaluated measuring the bioluminescence inhibition of Vibrio fischeri and performing the yeast estrogen screening assay, respectively.     

Formation of furan in baby food products: Identification and technical challenges

Furan is generally produced during thermal processing of various foods including baked, fried, and roasted food items such as cereal products, coffee, canned, and jarred prepared foods as well as in baby foods. Furan is a toxic and carcinogenic compound to humans and may be a vital hazard to infants and babies. Furan could be formed in foods through thermal degradation of carbohydrates, dissociation of amino acids, and oxidation of polyunsaturated fatty acids. The detection of furan in food products is difficult due to its high volatility and low molecular weight. Headspace solid-phase microextraction coupled with gas chromatography/mass spectrometer (GC/MS) is generally used for analysis of furan in food samples. The risk assessment of furan can be characterized using margin of exposure approach (MOE). Conventional strategies including cooking in open vessels, reheating of commercially processed foods with stirring, and physical removal using vacuum treatment have remained unsuccessful for the removal of furan due to the complex production mechanisms and possible precursors of furan. The innovative food-processing technologies such as high-pressure processing (HPP), high-pressure thermal sterilization (HPTS), and Ohmic heating have been adapted for the reduction of furan levels in baby foods. But in recent years, only HPP has gained interest due to successful reduction of furan because of its nonthermal mechanism. HPP-treated baby food products are commercially available from different food companies. This review summarizes the mechanism involved in the formation of furan in foods, its toxicity, and identification in infant foods and presents a solution for limiting its formation, occurrence, and retention using novel strategies.