Preparation of polyacrylamide hydrogels at various charge densities by postmodification

In this study, first polyacrylamide hydrogels were synthesized by free‐radical crosslinking polymerization of acrylamide monomer with N,N′‐methylenebis(acrylamide) as a crosslinker in an aqueous solution at 22°C. Then, a series of hydrogels at various charge densities were prepared by partial hydrolysis of polyacrylamide precursors in a 0.1M sodium hydroxide solution at 60°C. The hydrolysis time was varied between 20 and 180 min. The chemical structures and internal morphologies of the hydrogels before and after alkaline hydrolysis were characterized with attenuated total reflectance/Fourier transform infrared and scanning electron microscopy measurements. The swelling ratio of the hydrolyzed hydrogels was measured in buffer solutions at various pHs. From differential curves of dQ_v/dpH versus pH (where Q_v is the equilibrium swelling ratio of the hydrogels), the volume phase transition pH of the hydrogels was found to be 4.33 ± 0.05, regardless of the charge density of the hydrogels. In water at 22°C, the hydrogels with greater charge density showed a more rapid swelling rate because of their higher porosity and hydrophilicity. Moreover, in buffer solutions with the pH changing from 9.0 to 2.0 at 22°C, the hydrogels with greater charge density also exhibited a more rapid deswelling rate than the hydrogels with less charge density. In conclusion, the postmodification method is a good way of preparing pH‐sensitive hydrogels with fast responsiveness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

CO2 emissions vs. CO2 responsibility: An input–output approach for the Turkish economy

Recently, global warming (greenhouse effect) and its effects have become one of the hottest topics in the world agenda. There have been several international attempts to reduce the negative effects of global warming. The Kyoto Protocol can be cited as the most important agreement which tries to limit the countries’ emissions within a time horizon. For this reason, it becomes important to calculate the greenhouse gas emissions of countries. The aim of this study is to estimate the amount of CO₂—the most important greenhouse gas—emissions, for the Turkish economy. An extended input–output model is estimated by using 1996 data in order to identify the sources of CO₂ emissions and to discuss the share of sectors in total emission. Besides, ‘CO₂ responsibility’, which takes into account the CO₂ content of imports, is estimated for the Turkish economy. The sectoral CO₂ emissions and CO₂ responsibilities are compared and these two notions are linked to foreign trade volume. One of the main conclusions is that the manufacturing industry has the first place in both of the rankings for CO₂ emissions and CO₂ responsibilities, while agriculture and husbandry has the last place.     

Investigating Some Physicochemical Properties and Fatty Acid Composition of Native Black Mulberry (<Emphasis Type="Italic">Morus nigra</Emphasis> L.) Seed Oil

The physicochemical properties of seed and seed oil obtained from the native black mulberry (Morus nigra L.) were investigated in 2008 and 2009. The results showed that the seed consisted of 27.5–33% crude oil, 20.2–22.5% crude protein, 3.5–6% ash, 42.4–46.6% carbohydrate and 112.2–152.0 mg total phenolics/100 g. Twenty different fatty acids were determined, with the percentages varying from 0.02% myristic acid (C14:0) to 78.7% linoleic acid (C18:2). According to the GC analysis of fatty acid methyl esters, linoleic acid (C18:2), followed by palmitic acid (C16:0), oleic acid (C18:1) and stearic acid (C18:0) were the major fatty acids, which together comprised approximately 97% of the total identified fatty acids. High C18:2 content (average 73.7%) proved that the black mulberry seed oil is a good source of the essential fatty acid, linoleic acid. Linolenic acid (C18:3) was also found in a relatively lower amount (0.3–0.5%). The α-tocopherol content was found to be between 0.17 and 0.20 mg in 100 g seed oil. The main sterols in the mulberry seed oil were β-sitosterol, Δ5-avenasterol, Δ5, 23-stigmastadienol, clerosterol, sitosterol and Δ5, 24-stigmastadienol. The present study stated that the native black mulberry seed oil can be used as a nutritional dietary substance and has great usage potential.     

Isothermal crystallization kinetics and mechanical properties of polycaprolactone composites with zinc oxide,oleic acid,and glycerol monooleate

The isothermal crystallization and mechanical behavior of polycaprolactone (PCL) with zinc oxide (ZnO) with oleic acid and glycerol monooleate (GMO) were studied. Theoretical melting points calculated by the Flory–Huggins and Thompson–Gibbs models were thoroughly compared with differential scanning calorimetry experimental observations. The isothermal crystallization kinetic parameters by Avrami analysis showed that crystallization was controlled by nucleation, crystal growth was spherical, and the nucleation type changed between thermal and athermal nucleation. X‐ray diffraction showed that when the additives were used together both the crystal thickness and the degree of crystallinity increased. A multiple‐response regression analysis was made with the ZnO, oleic acid, and GMO concentrations as variables and the crystallinity as output. Interaction parameters by the Pukanzky model were calculated from the tensile strength at the yield point and indicated that the addition of oleic acid or GMO improved the interface between the ZnO particles and PCL. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1259‐1275, 2013     

Production of oil-based binder by RAFT polymerization technique

In this study, air-blown linseed oil was styrenated by reversible addition–fragmentation chain transfer polymerization (RAFT). For this purpose, hydroperoxide groups were formed in the structure of linseed oil by blowing air through it. The oxidized oil was used as a macroinitiator in the styrenation process by RAFT technique using phenacyl morpholine dithiocarbamate (PMDC) as a RAFT agent. The obtained samples were characterized by GPC and FT-IR measurements. The effects of various parameters, such as the amount of PMDC, the number of peroxide groups, and the reaction time were investigated on polydispersity and molecular weight. For comparison, a copolymer sample was also prepared in the absence of PMDC. The film properties of all the samples were determined according to the related standards and compared. The sample obtained by the RAFT technique exhibited better film properties and a relatively narrow polydispersity, showing that the RAFT technique provides good control over the polymerization system in this study.     

The in vitro effects of some pesticides on carbonic anhydrase activity of Oncorhynchus mykiss and Cyprinus carpio carpio fish

Systemic carbonic anhydrase (CA) inhibitors are among the most powerful agents to lower intraocular pressure. Unfortunately, their use is frequently accompanied by undesired side effects. Some are due to the relatively large amounts of drug that have to be systematically administered to inhibit the CA in the ciliary processes. The aim of the present work was to study in vitro effects of some pesticides on CA enzyme obtained from blood of fish, which play a key role in salt- and osmoregulation and acid-base balance in the fish, Oncorhynchus mykiss and Cyprinus carpio carpio living in freshwaters, and compared with CA inhibitors. CA activities were significantly inhibited by pesticides and inhibitors. I(50) values of O. mykiss CA enzyme inhibited by lambda-cyhalothrin, deltametrin, diozinon, dorzolamide and brinzolamide were 6.05 x 10(-4), 1.48 x 10(-5), 6.84 x 10(-3), 3.82 x 10(-5) and 1.80 x 10(-6) mol/l, and that for C. c. carpio 6.86 x 10(-4), 4.70 x 10(-4), 3.92 x 10(-3), 8.34 x 10(-6) and 1.42 x 10(-6) mol/l, respectively. The pesticides used in this study inhibited the CA activity from different fish species to various degrees. It was found that the most effective inhibitor of CA enzyme within pesticides used was detrametrin. These findings observed in vitro could be useful in the understanding of the toxic effects that pesticides elicit on aquatic organisms in vivo.     

Preparation and Swelling Properties of Temperature‐Sensitive Semi‐Interpenetrating Polymer Networks Composed of Poly[(N‐tert‐butylacrylamide)‐co‐acrylamide] and Hydroxypropyl Cellulose

Summary: Temperature‐responsive hydrogels based on linear HPC and crosslinked P(NTBA‐co‐AAm) were prepared by the semi‐IPN technique. The structure of these semi‐IPN hydrogels was investigated by FT‐IR spectroscopy. An increase in normalized band ratios (A₂₉₈₀/A₁₆₆₅) was observed with increasing HPC content in the initial mixture. The swelling kinetics and water transport mechanism of these semi‐IPN hydrogels were examined and their temperature responsive behaviors were also investigated by measuring equilibrium swelling ratios and pulsatile swelling experiments. The results showed that these semi‐IPN hydrogels underwent a volume phase transition between 18 and 22 °C irrespective of the amounts of MBAAm and HPC. However, below the volume phase transition temperature, their equilibrium swelling ratios were affected by the amount of MBAAm and HPC. The pulsatile swelling experiments indicated that the lower the MBAAm and the higher HPC contents in semi‐IPN hydrogels the faster the response rate temperature change.

Equilibrium swelling ratios of the semi‐IPN P(NTBA‐co‐AAm)/HPC hydrogels in water shown as a function of temperature.     

Visual to tactile conversion of vector graphics.

Methods to automatically convert graphics into raised-line images have been recently investigated. In this paper, concepts from previous research are extended to the vector graphics case, producing tactile pictures in which important features are emphasized. The proposed algorithm extracts object boundaries and employs a classification process, based on a graphic's hierarchical structure, to determine critical outlines. A single parameter is introduced into the classification process, enabling users to tailor graphics to their own preferences. The resulting outlines are printed using a Braille printer to produce tactile output. Critical outlines are embossed with raised dots of highest height while other lines and details are embossed with a lower height. Psychophysical experiments including discrimination, identification, and comprehension are utilized to evaluate and compare the proposed algorithm. Results indicate that the proposed method outperforms other methods in all three considered tasks. The results also show that emphasizing important features significantly increases comprehension of tactile graphics, validating the proposed method's effectiveness in conveying visual information.