Evaluation of the effect of lichens on ceramic roofing tiles by scanning electron microscopy and energy-dispersive spectroscopy analyses

The effect of the actions of some lichens on the quality of ceramic roofing tiles was investigated in view of textural and microstructural changes considering their biocorrosion resistance. Two types (extruded and pressed) of the real ceramic roofing tiles aged 6 to 10 years, as well as the ceramic model systems formed with the additives of the specific chemical composition Cu-slag powder (10 wt%) and CuO powder (1 wt%), treated with various concentrations of oxalic acid (0.01 wt%, 0.1 wt%, and 4 wt%) were investigated. The thalli of lichen (Verrucaria nigrescens) growth on ceramic roofing tile were examined by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Investigation by SEM and EDS gave information regarding the ultrastructure characteristics of the thallus and the lichen-ceramic tile contact zone, allowing the observation of the hyphal penetration and filling up of the fissures and cracks by the lichens' hyphae. The CuO as the raw mixture additive changed the quality of the surface of the ceramic model systems as it has increased resistance to oxalic acid actions. The textural changes in the ceramic model systems and the formation of the identified destructive crystal phase, whewellite, were slowed down. The fundamental interactions between lichens and ceramic materials of the model systems have been identified as physico-chemical processes based on oxalic acid actions, which could cause ceramic matrix deterioration and consequently aging of ceramic roofing tile systems.     

Performance of Bluetooth Slave/Slave Bridge

The performance of a Bluetooth scatternet with a Slave/Slave bridge is analyzed using the tools of queueing theory. We analyze two possible scheduling policies: limited service and exhaustive service, and derive analytical results for the probability distribution of access delay (i.e., the time that a packet has to wait before being serviced) and end-to-end delay for both intra- and inter-piconet bursty traffic. The exhaustive service discipline was found to provide lower values for all delay variables, over a wide range of parameter values. All analytical results have been confirmed through simulations.     

Local orthogonal bases II: Window design

In the first part of this work we presented a technique to find a local orthogonal basis for a given vector space. The concept of a local orthogonal basis can be seen as an extension of the one-dimensional local cosine basis used, for example, in audio processing. Here the problem of window design is discussed, with a particular emphasis on the two-dimensional case, both in continuous and discrete time.     

New mesoporous carbon materials synthesized by a templating procedure

The new porous carbon materials were obtained by templating procedure using mesoporous silica (SBA-15) as template. The ordered mesoporous silica materials were synthesized by using Pluronic P123 (non-ionic triblock copolymer, EO₂₀PO₇₀O₂₀). SBA-15/cryogel carbon composites were obtained by sol–gel polycondenzation of resorcinol and formaldehyde in the presence of different amount of SBA-15. The polycondenzation was followed by freeze drying and subsequent pyrolysis. One set of SBA-15/sucrose carbon composites was prepared by using sucrose as carbon source. The silica template was eliminated by dissolving in hydrofluoric acid (HF) to recover the carbon material. The obtained carbon replicas were characterized by nitrogen adsorption–desorption measurements, X-ray diffraction and scanning electron microscopy (SEM). It was revealed that the samples have high specific surface (533–771 m² g^?1), developed meso- and micro-porosity and amorphous structure. Porous structure of carbon replicas was found to be a function of the carbon source, properties of SBA-15 and silica/carbon ratio. Room temperature adsorption of nitrogen and adsorption of phenol from aqueous solutions were investigated.     

Residential satisfaction among young people in post-socialist countries: the case of Serbia

Change in labor markets, extended education period and economic instability are negatively influencing housing accessibility of young adults. In post-socialist countries, such as Serbia, the biggest issues are the lack of supply volume and diversity of government subsidized housing, as well as the soaring prices of the newly built homes. As a result, young people are relying on the unregulated private rental market or their families to help them enter homeownership and acquire residential independence. There is an apparent need for affordable housing or policies which are catering to young people’s needs. The relevant body of research has been using residential satisfaction approach to provide an evaluation of the variety of housing available to young tenants. Hence, the primary purpose of this paper is to identify the factors which are significantly related or can predict the higher residential satisfaction and can be beneficial to the future policy makers in Serbia. To assess the residential satisfaction, following variables were included: socioeconomic characteristics, residential status, current housing characteristics, problems faced in the current dwelling, housing attribute preferences, privacy perception, dwelling proximity, neighborhood attachment, as well as overall residential satisfaction. The findings indicate that young people in Serbia had average levels of satisfaction with their housing despite the various problems and lack of privacy they were facing in the apartments. Higher residential satisfaction in this research was significantly predicted by the marital status of our respondents (single people were more satisfied), homeownership tenancy status, independent living arrangement, larger apartment size, greater levels of privacy and higher neighborhood attachment.     

Electrochemical oxidation of reverse osmosis concentrate on mixed metal oxide (MMO) titanium coated electrodes

Reverse osmosis (RO) membranes have been successfully applied around the world for wastewater reuse applications. However, RO is a physical separation process, and besides the clean water stream (permeate) a reverse osmosis concentrate (ROC) is produced, usually representing 15-25% of the feed water flow and containing the organic and inorganic contaminants at higher concentrations. In this study, electrochemical oxidation was investigated for the treatment of ROC generated during the reclamation of municipal wastewater effluent. Using laboratory-scale two-compartment electrochemical systems, five electrode materials (i.e. titanium coated with IrO₂-Ta₂O₅, RuO₂-IrO₂, Pt-IrO₂, PbO₂, and SnO₂-Sb) were tested as anodes in batch mode experiments, using ROC from an advanced water treatment plant. The best oxidation performance was observed for Ti/Pt-IrO₂ anodes, followed by the Ti/SnO₂-Sb and Ti/PbO₂ anodes. The effectiveness of the treatment appears to correlate with the formation of oxidants such as active chlorine (i.e. Cl₂/HClO/ClO⁻). As a result, electro-generated chlorine led to the abundant formation of harmful by-products such as trihalomethanes (THMs) and haloacetic acids (HAAs), particularly at Ti/SnO₂-Sb and Ti/Pt-IrO₂ anodes. The highest concentration of total HAAs (i.e. 2.7 mg L⁻¹) was measured for the Ti/SnO₂-Sb electrode, after 0.55 Ah L⁻¹ of supplied specific electrical charge. Irrespective of the used material, electrochemical oxidation of ROC needs to be complemented by a polishing treatment to alleviate the release of halogenated by-products.     

Modification of polyurethane‐coated fabrics by sol–gel thin films

Sol–gel derived silica and hybrid films from tetraethoxysilane (TEOS) and 3‐glycidyloxypropyltrimethoxysilane (GLYMO) were deposited by dip‐coating, in order to find the best treatment. GLYMO‐based treatments preserved textile feel of the material. The coatings were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and water contact angle measurement. IR spectra confirmed the existence of silicate network and successfully conducted modification for both precursors. DSC and TGA showed that the conditions of hydrolysis had greater influence on TEOS than GLYMO‐based treatments. Both treatments shifted the degradation onset to higher temperatures. SEM images showed that polyurethane surface and pores were completely covered and filled by silica or hybrid thin films forming a composite organic–inorganic coating. Hydrophobic effect was preserved for all the samples, except for a single treatment of the GLYMO, due to its polar epoxy group. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39914.     

Decreased Glucocorticoid Signaling Potentiates Lipid-Induced Inflammation and Contributes to Insulin Resistance in the Skeletal Muscle of Fructose-Fed Male Rats Exposed to Stress

The modern lifestyle brings both excessive fructose consumption and daily exposure to stress which could lead to metabolic disturbances and type 2 diabetes. Muscles are important points of glucose and lipid metabolism, with a crucial role in the maintenance of systemic energy homeostasis. We investigated whether 9-week fructose-enriched diet, with and without exposure to 4-week unpredictable stress, disturbs insulin signaling in the skeletal muscle of male rats and evaluated potential contributory roles of muscle lipid metabolism, glucocorticoid signaling and inflammation. The combination of fructose-enriched diet and stress increased peroxisome proliferator-activated receptors-α and -δ and stimulated lipid uptake, lipolysis and β-oxidation in the muscle of fructose-fed stressed rats. Combination of treatment also decreased systemic insulin sensitivity judged by lower R-QUICKI, and lowered muscle protein content and stimulatory phosphorylations of insulin receptor supstrate-1 and Akt, as well as the level of 11β-hydroxysteroid dehydrogenase type 1 and glucocorticoid receptor. At the same time, increased levels of protein tyrosine phosphatase-1B, nuclear factor-κB, tumor necrosis factor-α, were observed in the muscle of fructose-fed stressed rats. Based on these results, we propose that decreased glucocorticoid signaling in the skeletal muscle can make a setting for lipid-induced inflammation and the development of insulin resistance in fructose-fed stressed rats.