32 research outputs found

    Novel flame retardant thermoset resin blends derived from a free-radically cured vinylbenzylated phenolic novolac and an unsaturated polyester for marine composites

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    A phenolic novolac resin has been chemically reacted with 4-vinylbenzyl chloride to introduce polymerizable vinyl benzyl groups. The modified novolac spontaneously polymerizes like styrene, is physically and chemically compatible with a typical unsaturated polyester (UP) resin, and can be free-radically cured (crosslinked) alone and in mixtures with UP using styrene as a reactive diluent. The cured vinylbenzylated novolac and co-cured blends of it with UP show superior flame retardance to cured UP alone and have potential applications as matrix resins in glass-reinforced composite laminates especially for marine structures

    Complement-Binding Donor-Specific Anti-HLA Antibodies and Risk of Primary Graft Failure in Hematopoietic Stem Cell Transplantation

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    AbstractDetection of donor-specific anti-HLA antibodies (DSA) has been associated with graft rejection in all forms of transplantation. The mechanism by which DSA increase the risk of graft failure remains unclear. We hypothesized that complement-binding DSA are associated with engraftment failure in hematopoietic stem cell transplantation (HSCT) and analyzed 122 haploidentical transplant recipients tested prospectively for DSA. Retrospective analysis to detect C1q binding DSA (C1q+DSA) was performed on 22 allosensitized recipients. Twenty-two of 122 patients (18%) had DSA, 19 of which were women (86%). Seven patients with DSA (32%) rejected the graft. Median DSA level at transplant for patients who failed to engraft was 10,055 mean fluorescence intensity (MFI) versus 2065 MFI for those who engrafted (P = .007). Nine patients with DSA were C1q positive in the initial samples with median DSA levels of 15,279 MFI (range, 1554 to 28,615), compared with 7 C1q-negative patients with median DSA levels of 2471 MFI (range, 665 to 12,254) (P = .016). Of 9 patients who were C1q positive in the initial samples, 5 patients remained C1q positive at time of transplant (all with high DSA levels [median, 15,279; range, 6487 to 22,944]) and experienced engraftment failure, whereas 4 patients became C1q negative pretransplant and all engrafted the donor cells (P = .008). In conclusion, patients with high DSA levels (>5000 MFI) and complement-binding DSA antibodies (C1q positive) appear to be at much higher risk of primary graft failure. The presence of C1q+DSA should be assessed in allosensitized patients before HSCT. Reduction of C1q+DSA levels might prevent engraftment failure in HSCT

    Changes in the Treatment Responses to Artesunate-Mefloquine on the Northwestern Border of Thailand during 13 Years of Continuous Deployment

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    Background: Artemisinin combination treatments (ACT) are recommended as first line treatment for falciparum malaria throughout the malaria affected world. We reviewed the efficacy of a 3-day regimen of mefloquine and artesunate regimen (MAS ), over a 13 year period of continuous deployment as first-line treatment in camps for displaced persons and in clinics for migrant population along the Thai-Myanmar border. Methods and Findings: 3,264 patients were enrolled in prospective treatment trials between 1995 and 2007 and treated with MAS. The proportion of patients with parasitaemia persisting on day-2 increased significantly from 4.5% before 2001 to 21.9% since 2002 (p<0.001). Delayed parasite clearance was associated with increased risk of developing gametocytaemia (AOR = 2.29; 95% CI, 2.00-2.69, p = 0.002). Gametocytaemia on admission and carriage also increased over the years (p = 0.001, test for trend, for both). MAS efficacy has declined slightly but significantly (Hazards ratio 1.13; 95% CI, 1.07-1.19, p<0.001), although efficacy in 2007 remained well within acceptable limits: 96.5% (95% CI, 91.0-98.7). The in vitro susceptibility of P. falciparum to artesunate increased significantly until 2002, but thereafter declined to levels close to those of 13 years ago (geometric mean in 2007: 4.2 nM/l; 95% CI, 3.2-5.5). The proportion of infections caused by parasites with increased pfmdr1 copy number rose from 30% (12/ 40) in 1996 to 53% (24/45) in 2006 (p = 0.012, test for trend). Conclusion: Artesunate-mefloquine remains a highly efficacious antimalarial treatment in this area despite 13 years of widespread intense deployment, but there is evidence of a modest increase in resistance. Of particular concern is the slowing of parasitological response to artesunate and the associated increase in gametocyte carriage. © 2009 Carrara et al

    Fire and mechanical properties of a novel free-radically cured phenolic resin based on a methacrylate-functional novolac and of its blends with an unsaturated polyester resin

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    A novel phenolic novolac resin bearing methacrylate functional groups has been synthesized by reaction of the novolac with methacryloyl chloride. This resin has been mixed with styrene and cured (crosslinked) free-radically under the relatively low temperature conditions used to cure unsaturated polyester/styrene mixtures, i.e. there is no need to employ the high temperatures and pressures that are required to cure conventional phenolic resins. Homogeneous cured blends of the methacrylated novolac with unsaturated polyester and styrene have been prepared also. The cured methacrylated novolac, and its blends with unsaturated polyester, are rigid materials with good mechanical strength, and have glass transition temperatures, thermal stabilities and flame retardancies superior to those of cured unsaturated polyester alone. Fire and mechanical properties of a novel free-radically cured phenolic resin based on a methacrylate-functional novolac and of its blends with an unsaturated polyester resin

    Two new rotenoid glycosides from the rhizomes of <i>Stemona curtisii</i> Hook. f

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    Two new rotenoid glycosides named stemonal 11-O-β-D-glucopyranoside and 6-O-methylstemonal 11-O-β-D-glucopyranoside together with ten known metabolites were isolated from the rhizomes of Stemona curtisii. The chemical structures of the new compounds were elucidated based on the analysis of their 1D and 2D NMR and HRESIMS, while the sugar unit and absolute configuration were determined by chemical hydrolysis and ECD analysis. Among the tested compounds for anti-α-glucosidase assay, stemonal showed an inhibitory effect (IC50 = 38.67 µM), which is 2.4-fold more potent than acarbose. Cytotoxic evaluation against the lung adenocarcinoma A549 cell line indicated that none of the compounds were strongly active to suppress the cancer cell growth at 100 µM. This work describes the occurrence of rotenoids bearing a sugar moiety, which are reported for the first time in the genus Stemona. The isolated compound’s α-glucosidase inhibitory potential provides insight for further investigation of natural rotenoids as anti-diabetic agents.</p
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