A review of experimental studies of the role of free-radicals in polyethylene oxidation

Publication date: Available online 11 July 2018Source: Polymer Degradation and StabilityAuthor(s): Pierangiola Bracco, Luigi Costa, Maria Paola Luda, Norman BillinghamAbstractThis paper reviews current understanding of the role of free radicals in the oxidation of polyethylene induced by high-energy irradiation (gamma or e-beam). To evaluate the reactivity, stability and mobility of different macroradicals, their reactions after gamma irradiation of different polyethylenes (LDPE, LLDPE, VLLDPE, HDPE, UHMWPE) are considered. Macroradicals are formed in all phases of PE (crystalline, amorphous and interphase). Their overall determination is possible only if both irradiation and detection are carried out at 100 K, or below. At this temperature, the most abundant macroradical formed is the secondary alkyl macroradical (R’’°). On gradually raising the temperature, the macroradicals decay with formation of vinylene double bonds and molecular hydrogen. At room temperature, the macroradical concentration is about 4% of the original quantity at 100 K for LDPE and around 15% for HDPE. In HDPE and UHMWPE; the macroradicals are mainly present in the crystalline phase and in short times (hours) they migrate to the amorphous phase. In LDPE and LLDPE macroradicals are mainly allylic, present in minimal amounts at the crystalline-amorphous interphase. In the nearly fully amorphous VLDPE no residual macroradicals can be detected at room temperature.The mobility of R’...
Source: Polymer Degradation and Stability - Category: Chemistry Source Type: research

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In this study, we have systematically reviewed the relationships between KS and the cardiovascular system and the management of cardiovascular complication. In summary, patients with KS display increased cardiovascular risk profile, characterized by increased prevalence of metabolic alterations including dyslipidemia, diabetes mellitus (DM), and abnormalities in biomarkers of cardiovascular disease. KS subjects are characterized by subclinical abnormalities in endothelial function and in left ventricular (LV) systolic and diastolic function, which - when associated with chronotropic incompetence - may negatively influence ...
Source: Expert Review of Endocrinology and Metabolism - Category: Endocrinology Tags: Expert Rev Endocrinol Metab Source Type: research
Authors: Bereket A PMID: 30786706 [PubMed - in process]
Source: JCRPE Journal of Clinical Research in Pediatric Endocrinology - Category: Endocrinology Tags: J Clin Res Pediatr Endocrinol Source Type: research
Conclusions: In patients with cirrhosis, those with concurrent elevation of HVPG and LS had the highest long-term mortality rates. However, when either HVPG or LS alone was elevated, mortality did not increase significantly. PMID: 30791681 [PubMed - as supplied by publisher]
Source: The Korean Journal of Internal Medicine - Category: Internal Medicine Authors: Tags: Korean J Intern Med Source Type: research
Publication date: Available online 22 February 2019Source: Biocatalysis and Agricultural BiotechnologyAuthor(s): Lale Nazari, Maryam MehrabiAbstractThe current study examines a thermotolerant alkaliphilic serine protease from newly isolated Bacillus sp. DEM07, which was purified with a 20% total protein yield and 14.28 fold purification. The molecular weight of the enzyme was estimated to be 27.5 kDa. The Km and Vmax values of the purified enzyme were found to be 0.06 mg/ml and 1.25 μmol/min, respectively. The enzyme maintained activity and stability over the 30–55 °C temperature range exhibiting its o...
Source: Biocatalysis and Agricultural Biotechnology - Category: Biotechnology Source Type: research
Authors: Qureshi AA, Friedman AJ Abstract Since the first reported cases in 2007, idiopathic mast cell activation syndrome has been increasingly recognized. Understanding of the cutaneous manifestations of this condition is imperative for dermatologists given the substantial clinical heterogeneity in its presentation and high estimated prevalence. A review of PubMed® and SCOPUS® databases was performed in order to investigate the most common dermatologic manifestations of idiopathic mast cell activation syndrome. Evidence to date suggests that flushing, pruritus, and clotting dysfunction or bleeding disorde...
Source: Journal of Drugs in Dermatology - Category: Dermatology Tags: J Drugs Dermatol Source Type: research
Conclusion: Topical minoxidil is efficacious for the treatment of hair loss due to male and female androgenic alopecia, alopecia areata, with case-by-case application for traction alopecia, hair transplantation, and congenital hair disorders. Combination therapies using minoxidil with systemic, topical, and injectable therapies demonstrate increased effectiveness over monotherapies. J Drugs Dermatol. 2019;18(2):155-160. PMID: 30794366 [PubMed - as supplied by publisher]
Source: Journal of Drugs in Dermatology - Category: Dermatology Tags: J Drugs Dermatol Source Type: research
Authors: Frost ML, Hrynewycz K, Hanke CW Abstract Tumor thickness has been a key tool for prognosis of melanoma. However, with the advent of gene expression profile (GEP) assays for melanoma and the discovery of multiple melanoma subtypes, it is time to reassess how we view tumor thickness as a prognostic indicator.Herein we present ten questions for consideration by the shrewd practitioner when considering prognostic factors of melanoma. J Drugs Dermatol. 2019;18(2):148-151. PMID: 30794365 [PubMed - as supplied by publisher]
Source: Journal of Drugs in Dermatology - Category: Dermatology Tags: J Drugs Dermatol Source Type: research
Authors: Draelos ZD, Gunt H, Levy SB Abstract Background: Rosacea is characterized by irritation associated with erythema, telangiectasias and papules/pustules. Whole formula nature-based sensitive skin products are formulated to maintain skin barrier and appropriate hydration that can lead to soothing benefits. Objective: To evaluate the efficacy and tolerability of a regimen consisting of a cleanser containing natural oils, beeswax, and witch hazel and day and night creams containing natural oils, glycerin, and botanical anti-inflammatories (NR); and a synthetic dermatologist-recommended regimen of cetyl alcohol...
Source: Journal of Drugs in Dermatology - Category: Dermatology Tags: J Drugs Dermatol Source Type: research
Conclusion: The histologic findings of BCCs treated with vismodegib correlate with clinical response. J Drugs Dermatol. 2019;18(2):136-138. PMID: 30794363 [PubMed - as supplied by publisher]
Source: Journal of Drugs in Dermatology - Category: Dermatology Tags: J Drugs Dermatol Source Type: research
Conclusions: Superficial radiation therapy is an effective option for eliminating BCC and SCC on lower extremities of patients who opt for nonsurgical treatment. Using SRT for BCC and SCC in elderly patients resulted in a 97.4% cure rate. J Drugs Dermatol. 2019;18(2):130-134. PMID: 30794362 [PubMed - as supplied by publisher]
Source: Journal of Drugs in Dermatology - Category: Dermatology Tags: J Drugs Dermatol Source Type: research
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