Summary Crosslinked hydroxyethyl cellulose-g-poly(acrylic acid) (HEC-g-pAA) graft copolymer was prepared by grafting of acrylic acid
(AA) onto hydroxyethyl cellulose (HEC) using [Ce(NH4)2(NO3)6]/HNO3 initiator system in the presence of poly(ethyleneglycol diacrylate) (PEGDA) crosslinking agent in 1:1 (v/v) mixture of methanol
and water at 30 °C. Carboxyl content of copolymer was determined by neutralization of –COOH groups with NaOH solution and
sodium salt of copolymer (HEC-g-pAANa) was swelled in distilled water in order to determine the equilibrium swelling value
of copolymer. Both dry HEC-g-pAA and swollen HEC-g-pAANa copolymers were used in the heavy metal ion removal from three different
aqueous ion solutions as follows: a binary ion solution with equal molar contents of Pb2+and Cd2+, a triple ion solution with equal molar contents of Pb2+, Cu2+ and Cd2+, and a triple ion solution with twice Cu2+molar contents of Pb2+and Cd2+. Higher removal values on swollen HEC-g-pAANa were observed in comparison to those on dry polymer. The presence of Cu2+decreased the adsorption values for Pb2+ and Cd2+ ions on both types of HEC copolymer. However, with further increase in Cu2+ content both dry and swollen copolymers became apparently selective to Cu2+ removal and Cu2+ removal values exceeded the sum of adsorption values for Pb2+ and Cd2+. Maximum metal ion removal capacities were 1.79 and 0.85 mmol Me2+/gpolymer on swollen HEC-g-pAANa and dry HEC-g-pAA, respectively. 相似文献
In this study, Turkey's energy sector was overviewed during the period of 1970–2002. The total energy consumption (TEC) was modeled by using the economic growth (proxied by gross national product—GNP) and population increase, which are the two important factors to determine the energy consumption for developing countries. In addition, the relationship between the TEC and total CO2 (TCO2) emission was studied. For this purpose, regression analysis was performed and the strong relationship between TEC and TCO2 (R2=0.998) was modeled. Also, results showed that a regression model can be used to predict the TEC from the country population and the GNP with high confidence (R2=0.996). 相似文献
Summary In situ fluorescence and light scattering techniques were used to study the formation of heterogeneities during the free-radical crosslinking polymerization of sodium acrylate (NaAc) in the presence of N,N'-methylene(bisacrylamide) (BAAm) as a crosslinker. Pyranine was used as a fluorescence probe in the experiments. The reactions were carried out at room temperature and at a monomer concentration of 20.6 w/v% in water. It was found that the gel forming system became turbid at the start of the reaction; continuing polymerization and crosslinking reactions turned the opaque gels into slightly opaque and finally transparent gels. Two peaks were observed both in the scattered and emitted light intensities versus the reaction time plots. The first peak corresponds to the formation and growth of the phase separated domains whereas the second peak reflects the macrogelation point in the reaction system. Received: 14 June 1999/Revised version: 10 October 1999/Accepted: 10 October 1999 相似文献
Electrochemical genosensors for the detection of the Factor V Leiden mutation from polymerase chain reaction (PCR) amplicons using the oxidation signal of colloidal gold (Au) is described. A pencil graphite electrode (PGE) modified with target DNA, when hybridized with complementary probes conjugated to Au nanoparticles, responded with the appearance of a Au oxide wave at approximately +1.20 V. Specific probes were immobilized onto the Au nanoparticles in two different modes: (a) Inosine-substituted probes were covalently attached from their amino groups at the 5' end using N-(3-dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (NHS) as a coupling agent onto a carboxylate-terminated l-cysteine self-assembled monolayer (SAM) preformed on the Au nanoparticles, and (b) probes with a hexanethiol group at their 5' phosphate end formed a SAM on Au nanoparticles. The genosensor relies on the hybridization of the probes with their complementary targets, which are covalently immobilized at the PGE surface. Au-tagged 23-mer capture probes were challenged with the synthetic 23-mer target, 131-base single-stranded DNA or denatured 256-base polymerase chain reaction (PCR) amplicon. The appearance of the Au oxidation signal shortened the assay time and simplified the detection of the Factor V Leiden mutation from PCR amplified real samples. The discrimination between the homozygous and heterozygous mutations was also established by comparing the peak currents of the Au signals. Numerous factors affecting the hybridization and nonspecific binding events were optimized. The detection limit for the PCR amplicons was found to be as low as 0.78 fmol; thus, it is suitable for point-of-care applications. 相似文献
Environmental impact assessment (EIA) is a tool for decision makers to take into account the possible effects of a proposed project on the environment and is also a process for collecting the data related to a project design and project area. Different techniques are used for the EIA process. In recent years, including the design and development of databases, classification systems, computer models and expert systems have been used extensively in impact assessment studies. Knowledge-based systems referred to as expert systems and different computer-based systems are an emerging technology in information processing and are becoming increasingly useful tools in different applications areas including EIA studies. Their use for EIA has been quite limited in developing countries, because of the constraints on resources, particularly in expertise and data.
In this study, a knowledge-based software—ÇEDINFO—developed by authors was introduced. ÇEDINFO to be used for EIA practices on energy-generating stations was designed based on the legal EIA process in Turkey. According to the EIA Regulation enacted in Turkey in 1993, energy-generating stations (thermal power station, hydraulic station, nuclear station) in different categories require mandatory EIA reports duly approved by The Ministry of Environment and Forestry before their construction. ÇEDINFO primarily aims to provide educational support for EIA practices and decision-makers on energy-generating stations. 相似文献
Polymer Bulletin - In this work, we successfully synthesized silver-doped polyaniline (NPANI-Ag-X; X represents I− and BF4− dopants,) by using chemical oxidation polymerization in... 相似文献
In order to avoid the curing stage in formed coke production, the effects of hardeners, on the tensile strength of the briquettes bonded with resole binders of F / P = 2.0 and N / P ratios ranging 0.1–0.5, were studied. The raw briquettes were produced by mixing the resole binders containing these hardeners, with the coke breeze. They were hardened at room temperature for 24 h and also at 200 °C for 2 h. The briquettes were also produced from the resole binders of the same N / P but containing no hardener, and cured at 200 °C for 2 h. The tensile strengths of the briquettes were measured. H3PO4 resulted in the briquettes having the lowest tensile strength under any conditions investigated. H2SO4 and p-TSA hardeners were found to be unsuitable for the aim of this investigation, because they could not fully harden the briquettes at room temperature. ATP resulted in the briquettes of the highest tensile strength of 52.13 MPa, with the resole binder of N / P = 0.1 after 24 h hardening at room temperature but resulted in briquettes of relatively lower tensile strength when the N / P ratio of resoles was increased. By blending ATP and p-TSA it became possible to produce formed coke with sufficient tensile strength by hardening them at room temperature. 相似文献