In 2021, global plastics production was 390.7 Mt; in 2022, it was 400.3 Mt, showing an increase of 2.
View Article and Find Full Text PDFBiobased hydroxyl-terminated polybutadiene (HTPB) was successfully synthesized in a one-pot reaction via metathesis degradation of industrial rubbers. Thus, polybutadiene (PB) and poly(styrene-butadiene-styrene) (SBS) were degraded via metathesis with high yields (>94%), using the fatty alcohol 10-undecen-1-ol as a chain transfer agent (CTA) and the second-generation Grubbs−Hoveyda catalyst. The identification of the hydroxyl groups (-OH) and the formation of biobased HTPB were verified by FT-IR and NMR.
View Article and Find Full Text PDFUnsaturated copolyesters are of great interest in polymer science due to their broad potential applications and sustainability. Copolyesters were synthesized from the ring-opening metathesis copolymerization of -6-hexadecenlactone (HDL) and norbornene (NB) using ruthenium-alkylidene [Ru(Cl)(=CHPh)(1,3-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)(PCy)] (), [Ru(Cl)(=CHPh)(PCy)] (), and ruthenium-vinylidene [RuCl(=C=CH(-CHCF))(PCy)] () catalysts, respectively, yielding HDL-NB copolymers with different ratios of the monomer HDL in the feed. The activity of -heterocyclic-carbene (NHC) () and phosphine ( and ) ligands containing ruthenium-carbene catalysts were evaluated in the synthesis of copolymer HDL-NB.
View Article and Find Full Text PDFThe future availability of synthetic polymers is compromised due to the continuous depletion of fossil reserves; thus, the quest for sustainable and eco-friendly specialty polymers is of the utmost importance to ensure our lifestyle. In this regard, this study reports on the use of oleic acid as a renewable source to develop new ionomers intended for proton exchange membranes. Firstly, the cross-metathesis of oleic acid was conducted to yield a renewable and unsaturated long-chain aliphatic dicarboxylic acid, which was further subjected to polycondensation reactions with two aromatic diamines, 4,4'-(hexafluoroisopropylidene)bis(-phenyleneoxy)dianiline and 4,4'-diamino-2,2'-stilbenedisulfonic acid, as comonomers for the synthesis of a series of partially renewable aromatic-aliphatic polyamides with an increasing degree of sulfonation (DS).
View Article and Find Full Text PDFAim: To provide insights into the capacity to conduct health technology assessment (HTA) in Central, Eastern, and South-Eastern Europe (CESEE), taking account of technical, financial, networking, and human resources.
Methods: An e-mail survey of 257 CESEE key informants involved in HTA was undertaken between March and April 2014. Contact e-mail addresses were identified from the internet.
This study reports on the degradation of natural rubber (NR) via crossmetathesis with mandarin oil and d-limonene, an abundant compound in essential oils; that were used as chain transfer agents (CTAs) and green solvents. Reactions were performed in the presence of the ruthenium-alkylidene catalysts (PCy₃)₂(Cl)₂Ru=CHPh (I) and (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) (PCy₃)Cl₂Ru=CHPh (II), respectively. Catalyst II bears an N-heterocyclic carbene ligand (NHC) bounded to the ruthenium atom, which has a strong basic character; therefore it is more active toward trisubstituted olefins in comparison with catalyst I.
View Article and Find Full Text PDFObjective: To analyze the number of inappropriate stays generated by patients admitted through a pulmonology department over a 1-year period and to identify the causes and predictors of those stays.
Patients And Methods: A representative sample of hospital stays corresponding to patients admitted by the pulmonology department at Hospital de Valme, Seville, Spain, in 2004 was analyzed retrospectively using the Appropriateness Evaluation Protocol. The review was conducted by 2 physicians who did not belong to the pulmonology department.
CD4+ T cells that constitutively express CD25 exhibit powerful suppressive properties. Such cells have been denominated regulatory T cells (T(R)). Alterations in T(R)cells are known to cause organ-specific autoimmune disease in animal models.
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