Preparation of novel nanocomposite hydrogels opens up new avenues to next generation of biocompatible materials to be used in bioengineering and drug delivery. Toward this goal, chitosan nanocomposite hydrogels using click chemistry inspired cross‐linking are prepared. To enable this, Diels–Alder reaction of furan‐containing chitosan and maleimide‐coated gold nanoparticles is employed. The viscoelastic properties of the obtained nanocomposites as well as the effect of the nanoparticles as cross‐linkers are studied, indicating that they play significant role in hydrogel formation and stability. Nanoparticle‐enriched hydrogels are also found to demonstrate pH‐sensitivity therefore showing their potential for future biosensing applications.
The adequate correlation of experimental phase equilibrium data by using any thermodynamic model represents a key point for the rigorous design of the chemical processes. However, this data correlation process remains a challenging problem, due to the high nonlinearity of the models used and the consequent problems of convergence. The present work analyzes the nonrandom two-liquids mode (NRTL) model to check the relation between the values of the binary interaction parameters and the corresponding phase equilibria that the NRTL model can or cannot reproduce. Additionally, in the case of the LLE, empirical equations have been established as a function of the nonrandomness parameter, to model the trajectory of the different miscibility boundaries observed. These functions can be used as constraints in the experimental data correlation procedure to reduce the search space and guarantee the consistency of the obtained binary interaction parameters with the experimental behavior of the system under study. 相似文献
In this work a series of MCM-41 catalysts have been prepared by eliminating the template by calcination and by different extraction treatments. The extracted samples were also calcined and aluminium ion exchanged. A hydrothermal stability test of the final materials has also been performed. N2 adsorption isotherms, NH3 thermal desorption, X-ray fluorescence, X-ray diffraction, 27Al NMR and thermogravimetry of each material have been determined in order to establish the influence of the procedure used for template elimination on the physicochemical and textural properties of the material. Moreover, the ability of the different catalysts prepared for reducing the toxicity of the mainstream smoke evolved when cigarettes are smoked has been checked too. The results obtained show that the final properties of the catalyst depend noticeably on the experimental conditions used in the template extraction process (i.e., the solvent selected, the solvent:catalyst ratio, the temperature, the contact time and the number of successive extraction steps). Thus, the adequate selection of such conditions permits a material to be obtained with properties very similar to that of the calcined MCM-41 material. As a conclusion, the material showing the best properties, among the catalysts studied in this work, produces a mean reduction of the yield of the different compounds analyzed in the gases and in the condensed products retained in the filters and in the traps of around 35%, 75% and 45%, respectively, which are slightly higher than the values corresponding to the calcined MCM-41 used as reference (i.e., 25%, 56% and 40%, respectively). These reductions results in an increase of the amount of ashes of around 2 mg/cigarette due to the presence of the catalyst. 相似文献
A new method for the measurement of SI traceable carbon isotope amount ratios using a multicollector inductively coupled mass spectrometer (MC-ICPMS) is reported for the first time. Carbon (13)C/(12)C isotope amount ratios have been measured for four reference materials with carbon isotope amount ratios ranging from 0.010659 (delta(13)C(VPDB) = -46.6 per thousand) to 0.011601 (delta(13)C(VPDB) = +37 per thousand). Internal normalization by measuring boron (11)B/(10)B isotope amount ratios has been used to correct for the effects of instrumental mass bias. Absolute (13)C/(12)C ratios have been measured and corrected for instrumental mass bias and full uncertainty budgets have been calculated using the Kragten approach. Corrected (13)C/(12)C ratios for NIST RM8545 (Lithium Carbonate LSVEC), NIST RM8573 (L-Glutamic Acid USGS40), NIST RM8542 (IAEA-CH6 Sucrose) and NIST RM8574 (L-Glutamic Acid USGS41) differed from reference values by 0.06-0.20%. Excellent linear correlation (R = 0.9997) was obtained between corrected carbon isotope amount ratios and expected carbon isotope amount ratios of the four chosen NIST RMs. The method has proved to be linear within this range (from (13)C/(12)C = 0.010659 to (13)C/(12)C =0.011601), and therefore, it is suitable for the measurement of carbon isotope amount ratios within the natural range of variation of organic carbon compounds, carbonates, elemental carbon, carbon monoxide, and carbon dioxide. In addition, a CO2 gas sample previously characterized in-house by conventional dual inlet isotope ratio mass spectrometry has been analyzed and excellent agreement has been found between the carbon isotope amount ratio value measured by MC-ICPMS and the IRMS measurements. Absolute values for carbon isotope amount ratios traceable to the SI are given for each NIST RM, and the combined uncertainty budget (including instrumental error and each parameter contributing to Russell expression for mass bias correction) has been found to be < 0.1% for the four materials. The advantage of the method versus conventional gas source isotope ratio mass spectrometry measurements is that carbon isotope amount ratios are measured as C(+) instead of CO2(+), and therefore, an oxygen (17)O correction due to the presence of (12)C(17)O(16)O(+) is not required. Organic compounds in solution can be measured without previous derivatization, combustion steps, or both, thus making the process simple. The novel methodology opens new avenues for the measurement of absolute carbon isotope amount ratios in a wide range of samples. 相似文献
Poly(3,4-ethylenedioxithiophene)/poly(styrene sulphonate) (PEDOT/PSS) aqueous dispersions were mixed with aqueous gold nanoparticle and aqueous silver nanoparticle colloids. PEDOT/gold nanoparticles (Au NP) and PEDOT/silver nanoparticles (Ag NP) films were obtained by solvent casting the corresponding aqueous solutions. The nanocomposite films showed the optical characteristics associated with both the surface plasmon absorption resonance of the metal nanoparticles and the excitation of the bipolaron band of the conducting polymer. As an interesting application we demonstrate the use of metal nanoparticles to tune the color of PEDOT based electrochromic films from blue to violet in the case of Au NP or green in the case of Ag NP. 相似文献