Theoretical investigation of ZIFs as adsorbents or membranes for separating noble gas mixtures: applying a newer method for predicting performances

Journal of Porous Materials - Zeolitic imidazolate frameworks (ZIFs) possess similar topological structures with zeolites, however a number of characteristic properties of the ZIFs, such as easy...     

Ultrasound as pretreatment for drying garlic slices in microwave and convective dryer

Food Science and Biotechnology - The effects of ultrasound pretreatment (US) before hot air drying (HAD) and microwave drying (MWD) of garlic slices were investigated. For this aim ultrasonic bath...     

Preparation of pentadecane/poly(melamine‐urea‐formaldehyde) microcapsules for thermal energy storage applications

Phase change materials (PCMs) with suitable melting ranges for thermal energy storage applications are alkanes, paraffins, fatty acids, eutectic mixtures, and inorganic PCMs. Paraffinic hydrocarbons and fatty acids with low solubility in water are usually the preferred candidates. Pentadecane, which is an alkane hydrocarbon with the chemical formula C₁₅H₃₂, was used as PCM in this study. The pentadecane was microencapsulated with a poly(melamine‐urea‐formaldehyde (MUF)) shell for thermal energy storage. Pentadecane/poly(MUF) microcapsules were prepared by in situ polymerization method. The morphological analysis of pentadecane microcapsules was analyzed with scanning electron microscopy (SEM). Thermal properties of microcapsulated pentadecane were determined by differential scanning calorimetry (DSC). The results demonstrated that pentadecane/PUF microcapsules were prepared successfully, and they offer proper phase transition temperature range (8.7°C and 8.1°C) and heat enthalpy values (84.5 and ?88.2 kJ/kg) for thermal energy storage applications. According to the results, it was determined that pentadecane/poly(MUF) microcapsules have good potential for thermal energy storage applications.     

Devolatilization kinetics of olive leaves with application as a precursor for activated carbon production

The objectives of the study were to investigate the devolatilization kinetics of olive leaves and their utilization as precursors for activated carbon. The devolatilization process was performed using thermogravimetric analysis under nitrogen at heating rates of 10, 15, and 20°C min^?1 with kinetic evaluation by the Coats-Redfern and Horowitz-Metzger methods. Potassium hydroxide activated olive leaves were employed as precursors for the production of activated carbon at 700°C for 60?min. Brunauer–Emmett–Teller and infrared spectroscopy were used for the characterization of texture and chemical properties of activated carbon. The adsorption capacity of fabricated active carbon with 1422?m² g^?1 surface area for methyl orange was characterized and data fitted well with a Langmuir model (R²?=?0.9977). The monolayer adsorption capacity of the activated carbon on methyl orange was 714.86?mg?g^?1 and the kinetics followed a pseudo-second-order model.     

A survey of concentration of aflatoxin M1 in dairy products marketed in Turkey

The aim of this study was to examine the presence of aflatoxin M1 (AFM1) in dairy product samples by enzyme-linked immunosorbent assay (ELISA). Aflatoxin M1 were found in 135 (64%) out of 210 analyzed samples. Only 7% of dairy product samples were contaminated at levels above the legal limits. AFM1 was detected in 43 (86%) of milk samples (ranging from 1 to 30 ng/l), in 38 (63%) of cheese (ranging from 12 to 378 ng/kg), in 28 (56%) of yoghurt (ranging from 2.5 to 78 ng/kg) and in 26 (52%) of dairy dessert samples (ranging from 1.5 to 80 ng/kg). None of the raw milk samples contained levels above the Turkish legal limit. The AFM1 levels of 7(14%) yoghurt, 5 (10%) dairy dessert and 3 (5%) cheese samples were above the limits of the Turkish Food Codex. It is emphasized that the presence of AFM1 in dairy products may be regarded as a potential hazard for human health.     

Progressive Failure Analysis of Reinforced-Adhesively Single-Lap Joint

The failure behavior of reinforced-adhesively single-lap joints was investigated experimentally and numerically. The reinforced adhesive was produced by mixing waste composite particles and an epoxy-based commercial adhesive. The single-lap joint was prepared with an adhesive and unidirectional fiber glass/epoxy composite plates with a (0°/90°)₃ stacking sequence. Three types of adhesive were used: an un-reinforced adhesive (ADH), an adhesive mixed with glass fiber-reinforced epoxy resin composite plate particles (GFRC), and an adhesive mixed with carbon fiber-reinforced epoxy resin composite plate particles (CFRC). The adhesive thickness (ta) and overlap length (lap) were 0.4, 0.8, 1.2, and 1.6 mm and 10, 20, 30, and 40 mm, respectively. Progressive failure analysis was performed with the ANSYS? 11.0 finite element program using ANSYS? parametric design language (APDL) code. In the numerical study, the failure loads of the composite and the adhesive were determined with the Hashin failure criteria and the Tresca failure criteria, respectively. The difference between the experimental and numerical studies ranged from 2% to 10%. The failure load of reinforced-adhesively single-lap joints was 1.3–22.8% higher than that of the un-reinforced adhesive.     

The Expertise Effect on Web Accessibility Evaluation Methods

Web accessibility means that disabled people can effectively perceive, understand, navigate, and interact with the web. Web accessibility evaluation methods are needed to validate the accessibility of web pages. However, the role of subjectivity and of expertise in such methods is unknown and has not previously been studied. This article investigates the effect of expertise in web accessibility evaluation methods by conducting a Barrier Walkthrough (BW) study with 19 expert and 57 nonexpert judges. The BW method is an evaluation method that can be used to manually assess the accessibility of web pages for different user groups such as motor impaired, low vision, blind, and mobile users.

Our results show that expertise matters, and even though the effect of expertise varies depending on the metric used to measure quality, the level of expertise is an important factor in the quality of accessibility evaluation of web pages. In brief, when pages are evaluated with nonexperts, we observe a drop in validity and reliability. We also observe a negative monotonic relationship between number of judges and reproducibility: more evaluators mean more diverse outputs. After five experts, reproducibility stabilizes, but this is not the case with nonexperts. The ability to detect all the problems increases with the number of judges: With 3 experts all problems can be found, but for such a level 14 nonexperts are needed. Even though our data show that experts rated pages differently, the difference is quite small. Finally, compared to nonexperts, experts spent much less time and the variability among them is smaller, they were significantly more confident, and they rated themselves as being more productive. The article discusses practical implications regarding how BW results should be interpreted, how to recruit evaluators, and what happens when more than one evaluator is hired.

Supplemental materials are available for this article. Go to the publisher's online edition of Human–Computer Interaction for statistical details and additional measures for this article.     

Preparation and characterization of a clay-polyvinylpyridinium matrix for the removal of bacterial cells from water

Polyvinylpyridinium salts were immobilized onto a clay matrix and were then tested for their antibacterial properties. The clay-polyvinylpyridinium matrix was prepared by the copolymerization of γ-methacryloxypropyltriethoxy silane bonded covalently to clay and 4-vinylpyridine and subsequent quaternization with benzyl halides. Suspension tests for antibacterial properties of the immobilized bactericide against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa demonstrated the high activity of the pyridinium salts that are bonded to the polyacrylate spacer. Advantageously, these insoluble clay-polymer bactericides could be applied without any contamination by the substrate. This revised version was published online in November 2006 with corrections to the Cover Date.     

Ice-binding proteins that accumulate on different ice crystal planes produce distinct thermal hysteresis dynamics

Ice-binding proteins that aid the survival of freeze-avoiding, cold-adapted organisms by inhibiting the growth of endogenous ice crystals are called antifreeze proteins (AFPs). The binding of AFPs to ice causes a separation between the melting point and the freezing point of the ice crystal (thermal hysteresis, TH). TH produced by hyperactive AFPs is an order of magnitude higher than that produced by a typical fish AFP. The basis for this difference in activity remains unclear. Here, we have compared the time dependence of TH activity for both hyperactive and moderately active AFPs using a custom-made nanolitre osmometer and a novel microfluidics system. We found that the TH activities of hyperactive AFPs were time-dependent, and that the TH activity of a moderate AFP was almost insensitive to time. Fluorescence microscopy measurement revealed that despite their higher TH activity, hyperactive AFPs from two insects (moth and beetle) took far longer to accumulate on the ice surface than did a moderately active fish AFP. An ice-binding protein from a bacterium that functions as an ice adhesin rather than as an antifreeze had intermediate TH properties. Nevertheless, the accumulation of this ice adhesion protein and the two hyperactive AFPs on the basal plane of ice is distinct and extensive, but not detectable for moderately active AFPs. Basal ice plane binding is the distinguishing feature of antifreeze hyperactivity, which is not strictly needed in fish that require only approximately 1°C of TH. Here, we found a correlation between the accumulation kinetics of the hyperactive AFP at the basal plane and the time sensitivity of the measured TH.