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11.
Aida Avetisyan 《合成通讯》2013,43(17):2607-2609
A convenient procedure for the preparation of cerpegin is described. 相似文献
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Idris Zembouai Mustapha Kaci Stéphane Bruzaud Aida Benhamida Yves-Marie Corre Yves Grohens 《Polymer Testing》2013,32(5):842-851
The paper aims to study blend properties of biodegradable polymers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactide (PLA) prepared by melt mixing. Blend compositions based on PHBV/PLA were investigated according to the following weight ratios, i.e. 100/0, 75/25, 50/50, 25/75 and 0/100 wt%. The study showed through scanning electron microscopy (SEM) that blends of PHBV/PLA are not miscible. This is consistent with differential scanning calorimetry (DSC) data which indicate the presence of two distinct glass transition temperatures (Tg) and melting temperatures (Tm), attributed to the neat polymers, over all the range of blend compositions. Water and oxygen barrier properties of PHBV/PLA blends are significantly improved with increasing the PHBV content in the blend. Further, morphological analyzes indicated that increasing the PHBV content in the polymer blends results in increasing the PLA crystallinity due to the finely dispersed PHBV crystals acting as a filler and a nucleating agent for PLA. On the other hand, the addition of PLA to the blend results in a very impressive increase in the complex viscosity of PHBV. Moreover, the rheological data showed that, excluding the specific behavior of the neat polymers at low frequencies, i.e. less than 0.1 Hz, the complex viscosity of PHBV/PLA blends fits the mixing law well. 相似文献
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T. Umecky T. Takamuku T. Aida T. Makino T. Aizawa M. Kanakubo 《Journal of solution chemistry》2014,43(9-10):1539-1549
2H and 17O NMR relaxation times, T 1(2H) and T 1(17O), and 2H NMR chemical shifts, δ(2H), in CO2-saturated CD3OD and C2D5OD solutions were measured at 313.2 K over the pressure range up to ~6 MPa. The rotational correlation times, τ r, of the CD and OD axes within CD3OD and C2D5OD molecules and the CO axis within the CO2 molecule were determined from T 1(2H) and T 1(17O), and the magnetic susceptibility-corrected chemical shifts, δ corr, were derived from δ(2H). The differences in τ r and δ corr observed between the two alcohol systems: τ r and δ corr of OD in C2D5OD, decreased rapidly with increasing CO2 concentration, while those of OD in CD3OD remained almost unchanged at mole fractions of CO2, \( x_{\text CO_{2}} \) , lower than ~0.25 and then slightly decreased at higher \( x_{\text CO_{2}} \) . The hydrogen bonding structure in C2D5OD was found to be gradually broken down by CO2 dissolution. On the other hand, in CD3OD, it has been revealed that the hydrogen bonding structure can persist at \( x_{\text CO_{2}} \) < ~0.25 but then collapses at higher \( x_{\text CO_{2}} \) . 相似文献
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Aida Moreira Da Silva José Empis José J.c. Teixeira-Dias 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(1):81-97
In aqueous solution, the apparent association constant at room temperature for the 1 : 1 inclusion of S-(+)-carvone in - cyclodextrin is double of that for R-(-)-carvone, whereas, at 45 °C, both enantiomers have association constants two orders of magnitude smaller, with the S-(+) inclusion being then slightly weaker than the R-(-) encapsulation. Calculations carried out at the molecular mechanics, AM1 and STO-3G levels confirm the preferential inclusion of the S-enantiomer and provide important clues for understanding chiral discrimination by -cyclodextrin. 相似文献