Glycidyl azide polymer or poly(glycidyl azide) which is considered as an excellent energetic binder or plasticizer in advanced solid propellants is generally obtained by post-modification or ...azidation of poly(epichlorohydrin). Here we report that glycidyl azide can be directly homopolymerized through anionic ring-opening polymerization to access poly(glycidyl azide) using onium salts as initiator and triethyl borane as activator. Molar masses of poly(glycidyl azide) up to 11.0 Kg/mol are achieved in a controlled manner with a narrow polydispersity index (PDI ≤ 1.2). Similarly, alternating poly(glycidyl azide carbonate) are also prepared through alternating copolymerization of glycidyl azide with carbon dioxide. Lastly, the copolymerization of glycidyl azide with other epoxide monomers is carried out; the azido functions carried by glycidyl azide which are successfully incorporated into the backbones of polyethers and polycarbonates based on cyclohexene oxide and propylene oxide subsequently served to introduce other functions by click chemistry.
The concept of using a thermoresponsive ionic liquid (IL) with an upper critical solution temperature (UCST) as a draw solute in forward osmosis (FO) was successfully demonstrated here ...experimentally. A 3.2 M solution of protonated betaine bis(trifluoromethylsulfonyl)imide (HbetTf2N) was obtained by heating and maintaining the temperature above 56 °C. This solution successfully drew water from high-salinity water up to 3.0 M through FO. When the IL solution cooled to room temperature, it spontaneously separated into a water-rich phase and an IL-rich phase: the water-rich phase was the produced water that contained a low IL concentration, and the IL-rich phase could be used directly as the draw solution in the next cycle of the FO process. The thermal stability, thermal-responsive solubility, and UV–vis absorption spectra of the IL were also studied in detail.
In this investigation, a metal‐free process was developed that enables the synthesis of poly(propylene carbonate) (PPC) diols/polyols by copolymerization of CO2 with propylene epoxide (PO) under ...environmentally friendly and cost‐effective conditions. This process implies the recycling of triethylborane and of ammonium salts that both enter in the composition of the initiators used to copolymerize CO2 and PO. In complement to the above approach, a polymeric support, poly(diallyl dimethylammonium chloride), was synthesized and modified to carry ammonium carboxylate salts along its chain. The prepared polymeric initiator was utilized to copolymerize CO2 with PO under heterogeneous conditions. Not only were the polymerization results similar to the samples obtained under homogeneous conditions, but the polymer substrate could easily be recovered by simple filtration. The integrity of the polycarbonate diols/polyols and the recycling process were followed by 1H and 11B NMR spectroscopy, gel permeation chromatography, and matrix assisted laser desorption ionization time of flight (MALDI‐TOF) MS.
Ready for Industrialization: A cost‐effective and environmentally friendly process is developed for the recycling of triethyl borane and the tetrabutylammonium cation that both enter in the composition of the initiators for preparation of poly(propylene carbonate) diols/polys. In addition, a polymeric support that carries ammonium carboxylate salts along its chain can obtain similar polymerization results as soluble salts but is easily recovered by simple filtration.
The anionic ring-opening copolymerization (ROCOP) of epoxides, namely of ethylene oxide (EO), with anhydrides (AH) generally produces strictly alternating copolymers. With triethylborane ...(TEB)-assisted ROCOP of EO with AH, statistical copolymers of high molar mass including ether and ester units could be obtained. In the presence of TEB, the reactivity ratio of EO (
), which is normally equal to 0 in its absence, could be progressively raised to values lower than 1 or higher than 1. Conditions were even found to obtain
equal or close to 1. Samples of P(EO-
-ester) with minimal compositional drift could be synthesized; upon basic degradation of their ester linkages, these samples afforded poly(ethylene oxide) (PEO) diol samples of narrow molar mass distribution. In other cases where
were lower or higher than 1, the PEO diol samples eventually isolated after degradation exhibited a broader distribution of molar masses because of the compositional drift of initial P(EO-
-ester) samples.
The effect of sleep duration on cancer risk remains controversial. We aimed to quantify the available evidence on this relationship using categorical and dose-response meta-analyses.
Population-based ...cohort studies and case-control studies with at least three categories of sleep duration were identified by searching PubMed, EMBASE, and the Cochrane Library database up to July 2017.
Sixty-five studies from 25 articles were included, involving 1,550,524 participants and 86,201 cancer cases. The categorical meta-analysis revealed that neither short nor long sleep duration was associated with increased cancer risk (short: odds ratio OR = 1.01, 95% confidence intervals CI = 0.97-1.05; long: OR = 1.02, 95% CI = 0.97-1.07). Subgroup analysis revealed that short sleep duration was associated with cancer risk among Asians (OR = 1.36; 95% CI: 1.02-1.80) and long sleep duration significantly increased the risk of colorectal cancer (OR = 1.21; 95% CI: 1.08-1.34). The dose-response meta-analysis showed no significant relationship between sleep duration and cancer risk. When treated as two linear piecewise functions with a cut point of 7 h, similar nonsignificant associations were found (per 1-h reduction: OR = 1.02, 95% CI = 0.98-1.07; per 1-h increment: OR = 1.003, 95% CI = 0.97-1.03).
Categorical meta-analysis indicated that short sleep duration increased cancer risk in Asians and long sleep duration increased the risk of colorectal cancer, but these findings were not consistent in the dose-response meta-analysis. Long-term randomized controlled trials and well-designed prospective studies are needed to establish causality and to elucidate the mechanism underlying the association between sleep duration and cancer risk.
In this manuscript, we describe the synthesis of low molar mass polycarbonate diols by acid cleavage of labile acetal linkages included in high molar mass poly(ether-co-carbonate-co-acetal) ...terpolymers. These copolymers were prepared by terpolymerization of propylene oxide (PO) with o-phthalaldehyde (OPA) and carbon dioxide (CO2), using triethyl borane (TEB) as activator and an onium salt as initiator. The advantage of this strategy of synthesis of poly(propylene carbonate) diols (PPC-diols) lies in the minute amounts of TEB and initiator required. Moreover, OPA could be isolated through post-hydrolysis of the terpolymers and recycled for subsequent use. We also demonstrated that this strategy works for the synthesis of low molar mass poly(ethylene carbonate) diols (PEC-diols). The structural integrity of the terpolymers before and after acid treatment, the characterization of low molar mass PPC-diols, and recycling process of OPA were carried out by 1H NMR spectroscopy, gel permeation chromatography, and matrix-assisted laser desorption ionization time of flight (MALDI-TOF) MS.
To prospectively examine the association between diabetes and risk of prostate cancer defined by clinical and molecular features.
A total of 49,392 men from the Health Professionals Follow-up Study ...(HPFS) were followed from 1986 to 2014. Data on self-reported diabetes were collected at baseline and updated biennially. Clinical features of prostate cancer included localised, advanced, lethal, low-grade, intermediate-grade, and high-grade. Molecular features included TMPRSS2: ERG and PTEN subtypes. Cox proportional hazards regression models were used to evaluate the association between diabetes and incidence of subtype-specific prostate cancer.
During 28 years of follow-up, we documented 6733 incident prostate cancer cases. Relative to men free from diabetes, men with diabetes had lower risks of total (HR: 0.82, 95% CI: 0.75-0.90), localised (HR: 0.82, 95% CI: 0.74-0.92), low-and intermediate-grade prostate cancer (HR: 0.77, 95% CI: 0.66-0.90; HR: 0.77, 95% CI: 0.65-0.91, respectively). For molecular subtypes, the HRs for ERG-negative and ERG-positive cases were 0.63 (0.42-0.95) and 0.72 (0.46-1.12); and for PTEN-intact and PTEN-loss cases were 0.69 (0.48-0.98) and 0.52 (0.19-1.41), respectively.
Besides providing advanced evidence for the inverse association between diabetes and prostate cancer, this study is the first to report associations between diabetes and ERG/PTEN defined prostate cancers.
A facile route toward alternating polycarbonates by anionic copolymerization of carbon dioxide (CO2) and cyclohexene oxide (CHO), using lithium halide or alkoxide as initiators and ...triisobutylaluminum (TiBA) as activator, is reported. α,ω-Heterobifunctional and α,ω-dihydroxypoly(cyclohexene carbonate)s (PCHC) as well as poly(CHC-co-CHO) copolymers with different carbonate composition could also be easily synthesized by adjusting the amount of TiBA or by adding inert lithium salts. The value of this initiating system also resides in the easy access to PSt-b-PCHC (PSt: polystyrene) and PI-b-PCHC (PI: polyisoprene) block copolymers which can be derived by mere one-pot sequential addition of styrene or dienes first and then of CO2 and CHO under the same experimental conditions.
Human papillomavirus (HPV) is one of the most prevalent sexually transmitted viruses. Despite the increasing evidence of HPV prevalence in semen, the worldwide distribution of HPV types in semen and ...risk for male infertility remain inconclusive.
Four electronic databases were searched for English language studies conducted between January 1990 and December 2016 that reported HPV DNA prevalence in semen. Based on the PRISMA guidelines, HPV prevalence was estimated among general population and fertility clinic attendees, respectively, and heterogeneity testing was performed using Cochran's Q and I
statistics. The association between HPV positivity and male infertility was evaluated by a meta-analysis of case-control studies.
A total of 31 eligible studies comprising 5194 males were included. The overall prevalence of HPV DNA in semen was 11.4% (95% CI = 7.8-15.0%) in general population (n = 2122) and 20.4% (95% CI = 16.2-24.6%) in fertility clinic attendees (n = 3072). High-risk type prevalence was 10.0% (95% CI = 5.9-14.0%) and 15.5% (95% CI = 11.4-19.7%), respectively. HPV16 was the most common type, with a prevalence of 4.8% (95% CI = 1.7-7.8%) in general population and 6.0% (95% CI = 3.8-8.2%) in fertility clinic attendees. A significantly increased risk of infertility was found for males with HPV positivity in semen (OR = 2.93, 95% CI = 2.03-4.24).
Seminal HPV infection is common worldwide, which may contribute to the risk of male infertility.
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