In this study, acrylamide-based hydrogels are synthesized by free radical solution polymerization in aqueous solution using ethylene glycol dimethacrylate (EGDMA) and its derivative polyethylene glycol dimethacrylate (PEGDMA) with different molecular weights as crosslinkers in the solution medium. The Fourier transform infrared spectroscopy technique is used for the structural characterization of the hydrogels. Dynamic swelling tests are conducted on acrylamide-based hydrogels for the determination of the swelling characteristics with respect to different crosslinking concentrations at room temperature. The parameters of swelling kinetics and diffusion mechanisms of the hydrogels are calculated with the aid of the data obtained. Accordingly, PEGDMA and EGDMA absorption capacity is found to increase with increasing concentrations. The lowest and highest water absorption capacities in PEGDMA810 and EGDMA crosslinked hydrogels are 22.73–48.39 and 10.15–16.02 g/g, respectively. Water intake of hydrogels crosslinked by EGDMA and PEGDMAs followed Fickian nature type diffusion except for PEGDM810, which has a swelling exponent greater than 0.5 and so does not follow a Fickian type of diffusion. PEGDM810 showed the fastest diffusion rate of between 5.87 × 10?4 and 10.87 × 10?4 cm2 s?1. 相似文献
We have developed a base promoted simple, efficient and alternative approach for the synthesis of 4-amino-3-aroyl//heteroaroyl/acetyl-2-methylsulfanyl-naphthalene-1-carbonitriles by reaction of easily accessible 3,3-bis(methylthio)-1-aryl/heteroaryl/acetylprop-2-en-1-one and 2-cyanomethyl-benzonitrile. Reaction of 1-(2-halo/methoxy-phenyl)-3,3-bis(methylthio)prop-2-en-1-one and 2-cyanomethyl-benzonitrile under basic conditions also afforded 6-(methylthio)-7-oxo-7,12-dihydrobenzo[c]acridine-5-carbonitrile along with usual product. Structure of the synthesized product has been confirmed by single X-ray crystallography. 相似文献
A hybrid of reduced graphene oxide–palladium (RGO–Pd) nano- to submicron-scale particles was simultaneously chemically prepared using microwave irradiation. The electrochemical investigation of the resulting hybrid was achieved using cyclic voltammetry and differential pulse voltammetry. RGO–Pd had a higher current response than unmodified RGO toward the oxidation of morphine. Several factors that can affect the electrochemical response were studied, including accumulation time and potential, Pd loading, scan rate, and pH of electrolyte. At the optimum conditions, the concentration of morphine was determined using differential pulse voltammetry in a linear range from 0.34 to 12 μmol L?1 and from 14 to 100 μmol L?1, with detection limits of 12.95 nmol L?1 for the first range. The electrode had high sensitivity toward morphine oxidation in the presence of dopamine (DA) and of the interference compounds ascorbic acid (AA) and uric acid (UA). Electrochemical determination of morphine in a spiked urine sample was performed, and a low detection limit was obtained. Validation conditions including reproducibility, sensitivity, and recovery were evaluated successfully in the determination of morphine in diluted human urine.
Chemistry of Natural Compounds - One new and seven known secondary metabolites 1–8 were isolated, and the nematocidal and insecticidal activities of major compounds from Tanacetum... 相似文献
For this research, an examination on the magnetohydrodynamic flow of a micropolar fluid across a moving vertical porous plate for the presence of thermal radiation is achieved. It is necessary to translate the partial differential equations regulating the flow, heat, & mass transfer into dimensionless form employing proper non-dimensional variables, which are then cracked numerically by utilizing the Finite difference approach. Graphs are used to represent numerical values of various flow profiles; however, tables are used to represent the simulated values of rate coefficients. The velocity rises when the value of Grashof number, dimensionless viscosity ratio is raised, and the opposite effect is seen when the value of magnetic parameter, micro-gyration factor is raised. The result in skin friction coefficient improves when the values of magnetic parameter, micro-gyration factor, Prandtl number, and radiation are raised higher. 相似文献
Conducting polymers are considered as reactive gels which can sense the working ambient through their unique electrochemical reaction. Copolymers of aniline with o-toluidine for three different monomer compositions were synthesized chemically and were characterized using FTIR and UV-Vis spectroscopy, SEM, TGA, and cyclic voltammetry. The electrochemical reactive sensing characteristics with respect to the electrical and chemical working conditions of the copolymers were verified and compared through Chronopotentiometric responses in aqueous solutions of HCl by changing the reaction variables: applied current and chemical environment (electrolyte concentration) at a fixed constant charge. The consumed electrical energy during the electrochemical reaction of the copolymers varies linearly with the driving current and follows a logarithmic dependence on the electrolyte concentration. The consumed electrical energy during the reaction was found to act as the sensing parameter. At the same experimental condition, the sensitivity was associated with the conductivity of the copolymers. The highly conducting composition gives the highest sensitivity. These experimental results were fitted with the theoretical equation.
This work depicts the original combination of electrochemiluminescence (ECL) and bipolar electrochemistry (BPE) to map in real-time the oxidation of silicon in microchannels. We fabricated model silicon-PDMS microfluidic chips, optionally containing a restriction, and monitored the evolution of the surface reactivity using ECL. BPE was used to remotely promote ECL at the silicon surface inside microfluidic channels. The effects of the fluidic design, the applied potential and the resistance of the channel (controlled by the fluidic configuration) on the silicon polarization and oxide formation were investigated. A potential difference down to 6 V was sufficient to induce ECL, which is two orders of magnitude less than in classical BPE configurations. Increasing the resistance of the channel led to an increase in the current passing through the silicon and boosted the intensity of ECL signals. Finally, the possibility of achieving electrochemical reactions at predetermined locations on the microfluidic chip was investigated using a patterning of the silicon oxide surface by etched micrometric squares. This ECL imaging approach opens exciting perspectives for the precise understanding and implementation of electrochemical functionalization on passivating materials. In addition, it may help the development and the design of fully integrated microfluidic biochips paving the way for development of original bioanalytical applications. 相似文献
Journal of Thermal Analysis and Calorimetry - The field of nanofluids has received interesting attention since the concept of dispersing nanoscaled particles into a fluid was first introduced in... 相似文献
A novel synthesis of thiazolo[2,3-b]quinazolines 4(a–e), pyrido[2′,3′:4,5]thiazolo[2,3-b]quinazolines {5(a–e), 6(a–e), and 7(a–e)}, pyrano[2′,3′:4,5]thiazolo[2,3-b]quinazolines 8(a–e), and benzo[4,5]thiazolo[2,3-b]quinazoloine9(a–e) derivatives starting from 2-(Bis-methylsulfanyl-methylene)-5,5-dimethyl-cyclohexane-1,3-dione 2 as efficient α,α dioxoketen dithioacetal is reported and the synthetic approaches of these types of compounds will provide an innovative molecular framework to the designing of new active heterocyclic compounds. In our study, we also present optimization of the synthetic method along with a biological evaluation of these newly synthesized compounds as antioxidants and antibacterial agents against the bacterial strains, like S. aureus, E. coli, and P. aeruginosa. Among all the evaluated compounds, it was found that some showed significant antioxidant activity at 10 μg/mL while the others exhibited better antibacterial activity at 100 μg/mL. The results of this study showed that compound 6(c) possessed remarkable antibacterial activity, whereas compound 9(c) exhibited the highest efficacy as an antioxidant. The structures of the new synthetic compounds were elucidated by elemental analysis, IR, 1H-NMR, and 13C-NMR. 相似文献