A new type of poly(glycidyl methacrylate) microbeads with surface grafted iminodiacetic acid: Synthesis and characterization

In this study, firstly, uniform poly(glycidyl methacrylate) (PGMA) microbeads with an average diameter of 230 μm were synthesized by suspension polymerization of GMA monomer and ethylene glycol dimethacylate (EGDMA) crosslinker in the presence of benzoyl peroxide (BPO) initiator . Secondly, the PGMA microbeads obtained were modified with iminodiacetic acid (IDA) to afford a new type of microbeads carrying two pendant carboxylic acid groups on the surface. The IDA modification was followed by Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) measurements. The surface morphology and thermal behavior of the PGMA and their modificated form were also characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) techniques further confirming modification.     

Antioxidant capacities of Gundelia tournefortii L. extracts and inhibition on glutathione-S-transferase activity

Gundelia tournefortii L. is an important food source and a well-known medicinal plant in Eastern Anatolia. Therapeutic effects of medicinal plants are known to be closely related to their antioxidant capacities. Antioxidant activities of G. tournefortii, both for the aerial parts and seeds, were investigated by using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibition methods. The seeds were found to have higher antioxidant potential than the aerial, with IC₅₀ values of 0.073 mg/mL for DPPH scavenging and 0.146 mg/mL for lipid peroxidation inhibition capacities. In addition, total phenolic contents of the Gundelia tournefortii L. extracts, especially the seed extracts correlates to its high antioxidant activity with 105.1 ± 8.7 μg gallic acid equivalents (GAEs) per mg of seed extract. Plant extracts with high phenolics content are known to have important effects on various enzymes, as well as glutathione-S-transferases, which are important detoxification enzymes in phase II systems with an important role in developing multi-drug resistance to chemotherapy in tumour cells. Consequently, the effects of G. tournefortii extracts on crude cytosolic glutathione-S-transferase was also studied and the seed extracts have shown effective inhibition of cytosolic GST activity, with an IC₅₀ of 97.51 μg/mL.     

Metals,including vanadyl and nickel porphyrins,in the oil shales of Timahdit,Morocco

Vanadyl and nickel porphyrins have been isolated from a Cretaceous oil shale (Timahdit, Morocco) by solvent extraction and chromatography. Electronic absorption spectrophotometry and mass spectrometry have been used in the determination of the nature and proportion of the isolated complexes. A distinction between the metal content associated with porphyrinic systems and that associated with inorganic materials is made on the basis of metal determinations carried out on the bituminous shale and on the extract of organic material; the concentration of V and Ni observed in organic material is comparable to that found in heavy crude oils but these metals, present in nearly identical amounts, are entirely coordinated to porphyrinic systems.     

Improvement of Silver Extraction by Ultrafine Grinding Prior to Cyanide Leaching of the Plant Tailings of a Refractory Silver Ore

Ultrafine grinding (UFG) was proposed as a pretreatment method prior to cyanide leaching of old plant tailings of a refractory silver ore. Direct cyanidation of the as-received tailings (d₈₀: 100 µm) led to a low silver extraction of only ≤43% over 24 h. A size-based diagnostic study has demonstrated that the refractoriness of the tailings is essentially physical in character. Therefore, effects of particle size/UFG (d₉₉: 5–75 µm), concentrations of NaCN (0.75–2.25 g/L) and Pb(NO₃)₂ (0–500 g/t) on the extraction of silver were investigated using a Box–Behnken design. The statistical analysis of the experimental data (%Ag extraction at 1 h) revealed that particle size/UFG was the most significant parameter for the extraction of silver, which was substantially improved after UFG. A positive effect of increasing the concentration of NaCN was also observed particularly at finer particle sizes while the effect of concentration of Pb(NO₃)₂ was insignificant. Almost complete extraction for silver (i.e., ≥99%) was demonstrated to be possible at even higher concentrations of cyanide (>2.25 g/L NaCN) when using the finest material (d₉₉: 5 µm) over only 1 h of leaching. Albeit, the consumption of cyanide tended to increase with UFG or increasing the initial concentration of cyanide. The findings showed that UFG can be used as a suitable and environmentally sound pretreatment method to improve the extraction of silver from the refractory silver ore tailings. The diagnostic approach adopted in the current study has proved to be a useful analytical tool to determine the amenability of the ore to ultrafine-grinding as a pretreatment process.     

Temperature Dependency of Steady, Dynamic, and Creep-Recovery Rheological Properties of Ice Cream Mix

In this study, effect of processing temperature (5, 15, 25, and 35 °C) on the steady, dynamic, and creep recovery rheological properties of the ice cream mix (ICM) was investigated. It was found that processing temperature significantly affected all rheological parameters of the ICM sample. The flow behavior of the ICM sample was fitted to the Ostwald de Waele model. The magnitude of storage modulus (G′) was higher than that of loss modulus (G″) indicating that ICM sample had weak gel-like structure. Modified Cox–Merz rules were satisfactorily applied to the ICM sample to observe relationship between steady and dynamic shear properties. Additionally, Burger model was used to characterize the viscoelastic properties of the ICM sample. The gel strength (S) value was also calculated, and a decrease was observed with the increase of temperature. Arrhenius equation satisfactorily described the temperature dependency of the rheological parameters such as apparent viscosity at 50 s^?1 (η ₅₀), consistency coefficient (K), the instantaneous shear modulus of the Maxwell unit (G ₀), permanent deformation (J _∞ ), and S values that may be predicted by using established equations depending on the temperature. The increase in processing temperature caused a decrease in resistance of the mixture subjected to the deformation, which is very important for production of high quality ice cream.     

Stability of pre-twisted Leipholz' column

Summary The stability of a cantilever elastic column having a linear viscous internal damping subjected to uniformly distributed vertical and follower loads is investigated. The governing equations of motion for the flexural deformation in both directions of a pre-twisted slender column are derived and solved by using Galerkin's technique. The critical loads are obtained and represented in figures for various values of the damping, pre-twisting angle, rigidity ratio and non-conservativeness parameter. The cases of no damping and small damping are discussed for various values of the rigidity ratio and pre-twisting angle.With 6 Figures     

From UML/SPT models to schedulability analysis: approach and a prototype implementation using ATL

Model Driven Architecture (MDA) is a software development approach promoted by the OMG. MDA is based on two key concepts, models and model transformations. Several kinds of models are generally used throughout the development process to specify a software system and to support its analysis and validation. UML and its extensions, such as the UML profile for real-time systems (UML/SPT), are commonly used to define the structure and the behavior of software systems while other models, such as performance models or schedulability models, are more suitable for performance or schedulability analysis, respectively. In this paper we discuss a model transformation enabling the derivation of schedulability analysis models from UML/SPT models. As a proof of concepts, we present a prototype implementation of this model transformation using ATL. We provide a definition of the source and target metamodels using the metamodel specification language KM3 and we specify the transformation in an ATL module. We discuss the merits and limitations of our approach and of its implementation.     

Comparison of Rainfall-Runoff Relationship Modeling using Different Methods in a Forested Watershed

The daily rainfall-runoff relationship in an experimental watershed was modeled using a statistical method and an artificial neural network method. The estimations were examined and a performance evaluation was done. It was seen that the ANN method, FFBP (Feed Forward Back Propagation), provided closer flow estimations reproducing the shape of the observed hydrograph more realistic. The superiority of FFBP was reflected in the performance evaluation criteria. The extreme flows, i.e., high and low flows, were relatively better approximated by FFBP indicating its promise as a useful tool for hydrologic studies such as flood modeling. The Rational Method was also used, as a conventional tool, to predict the maximum discharge for selected return periods. It was found to be realistic for the forested watershed under consideration when the C coefficient was taken as 0.20 for the 10-year period.

     

Thermal and Morphological Properties of Organo Modified Nanoclay/Polyethylene Terephthalate Composites

The purpose of this study is polyethylene terephthalate (PET) and modified organo-nanoclay with different masses and to contribute to the different areas of use and literature by examining these nanocomposites physical, chemical and thermal features. In this study, nanocomposite films, which work in PET that is a type of polymeric material, and work into modified organo-nanoclays with different percentages, obtained with the method called as in situ polymerization. The chemical structures of nanocomposites prepared were investigated by fourier transform infrared spectroscopy. The surface morphologies of this nanocomposites were examined by scanning electron microscope. Their thermal properties were analyzed by differential scanning calorimetry and thermogravimetric analysis. According to the results obtained, the thermal stabilities of modified nanoclay composites got better than PET. Besides, while the percent of clay in the doped PET was rising, its fragility increased. At the same time, high mass of clay formed when the percent of contribution developed. Thus, the surface interaction of polymer–clay decreased, because the composed aggregations prevented the polymer matrix from going into the layer of clay.     

Evaluation of the NDVI in plant community composition mapping: a case study of Tersakan Valley,Amasya County,Turkey

Mapping the composition of plant community types requires reliable spatial data obtained from field surveys and satellite‐derived indices. The normalized difference vegetation index (NDVI) is the simplest and most frequently used index in plant applications. If relationships between the NDVI and plant cover abundance are determined, this information can be used in the mapping process. In this study, we investigated these possible connections for mapping the plant community composition of Tersakan Valley in Turkey. We collected georeferenced cover‐abundance (Braun‐Blanquet, BB) data from 1077 quadrats in the field, and derived an NDVI raster map from a Landsat Enhanced Thematic Mapper Plus (ETM+) image. Then we classified this NDVI map by using various methods and class numbers. Using bivariate correlation analysis, we explored the relationships between 26 classified NDVI maps and BB, and chose the classified NDVI map with the strongest correlation. We further examined this relationship by using scatter plots, histograms and paired samples t‐tests. According to the results, the NDVI (equal‐interval 15) classes between 4 and 8 corresponded with the BB classes between 1 and 5, respectively. Using this relationship, the spatial distribution of 43 different plant community compositions were determined in geographic information systems (GIS). The results indicate that the NDVI has the potential to map plant community composition reliably.