The potential of kaolin as a reinforcing filler for rubber composites with new sulfur cure systems

This paper was accepted for publication in the journal Journal of Reinforced Plastics and Composites and the definitive published version is available at https://doi.org/10.1177/0731684417712070.The effect of a large amount of kaolin (China clay) on the viscosity, cure, hardness, Young’s modulus, tensile strength, elongation at break, stored energy density at break, tear energy and compression set resistance of some sulfur-cured natural rubber, polybutadiene rubber and ethylene-propylene-diene rubber composites was investigated. The kaolin surface had been pre-treated with 3-mercaptopropyltrimethoxysilane to improve its dispersion in the rubbers. For natural rubber, the hardness and Young’s modulus improved, tensile strength and tear energy were unchanged and the remaining properties deteriorated when kaolin was added. The viscosity increased and the scorch and optimum cure times decreased whilst the cure rate rose with kaolin. For polybutadiene rubber and ethylene-propylene-diene rubber, with the exception of the compression set resistance, all the properties including the viscosity gained from the kaolin. The kaolin was found to be extending or non-reinforcing filler for natural rubber, and highly reinforcing for polybutadiene rubber and EPDM. In addition, the scorch and optimum cure times and cure rate of polybutadiene rubber benefitted, whereas with the exception of the scorch time, the optimum cure time and cure rate of ethylene-propylenediene rubber were adversely affected by kaolin

Polychlorinated biphenyls, cytochrome P450 1A1 (CYP1A1) polymorphisms, and breast cancer risk among African American women and white women in North Carolina: a population-based case-control study

INTRODUCTION: Epidemiologic studies have not shown a strong relationship between blood levels of polychlorinated biphenyls (PCBs) and breast cancer risk. However, two recent studies showed a stronger association among postmenopausal white women with the inducible M2 polymorphism in the cytochrome P450 1A1 (CYP1A1) gene. METHODS: In a population-based case-control study, we evaluated breast cancer risk in relation to PCBs and the CYP1A1 polymorphisms M1 (also known as CYP1A1*2A), M2 (CYP1A1*2C), M3 (CYP1A1*3), and M4 (CYP1A1*4). The study population consisted of 612 patients (242 African American, 370 white) and 599 controls (242 African American, 357 white). RESULTS: There was no evidence of strong joint effects between CYP1A1 M1-containing genotypes and total PCBs in African American or white women. Statistically significant multiplicative interactions were observed between CYP1A1 M2-containing genotypes and elevated plasma total PCBs among white women (P value for likelihood ratio test = 0.02). Multiplicative interactions were also observed between CYP1A1 M3-containing genotypes and elevated total PCBs among African American women (P value for likelihood ratio test = 0.10). CONCLUSIONS: Our results confirm previous reports that CYP1A1 M2-containing genotypes modify the association between PCB exposure and risk of breast cancer. We present additional evidence suggesting that CYP1A1 M3-containing genotypes modify the effects of PCB exposure among African American women. Additional studies are warranted, and meta-analyses combining results across studies will be needed to generate more precise estimates of the joint effects of PCBs and CYP1A1 genotypes

Near-infrared sensitivity enhancement of photorefractive polymer composites by pre-illumination

Among the various applications for reversible holographic storage media, a particularly interesting one is time-gated holographic imaging (TGHI). This technique could provide a noninvasive medical diagnosis tool, related to optical coherence tomography. In this technique, biological samples are illuminated within their transparency windowwith near-infrared light, and information about subsurface features is obtained by a detection method that distinguishes between reflected photons originating from a certain depth and those scattered from various depths. Such an application requires reversible holographic storage media with very high sensitivity in the near-infrared. Photorefractive materials, in particular certain amorphous organic systems, are in principle promising candidate media, but their sensitivity has so far been too low, mainly owing to their long response times in the near-infrared. Here we introduce an organic photorefractive material—a composite based on the poly(arylene vinylene) copolymer TPD-PPV—that exhibits favourable near-infrared characteristics. We show that pre-illumination of this material at a shorter wavelength before holographic recording improves the response time by a factor of 40. This process was found to be reversible. We demonstrate multiple holographic recording with this technique at video rate under practical conditions

Developmental disruption of perineuronal nets in the medial prefrontal cortex after maternal immune activation

© The Author(s) 2016. Maternal infection during pregnancy increases the risk of offspring developing schizophrenia later in life. Similarly, animal models of maternal immune activation (MIA) induce behavioural and anatomical disturbances consistent with a schizophrenia-like phenotype in offspring. Notably, cognitive impairments in tasks dependent on the prefrontal cortex (PFC) are observed in humans with schizophrenia and in offspring after MIA during pregnancy. Recent studies of post-mortem tissue from individuals with schizophrenia revealed deficits in extracellular matrix structures called perineuronal nets (PNNs), particularly in PFC. Given these findings, we examined PNNs over the course of development in a well-characterized rat model of MIA using polyinosinic-polycytidylic acid (polyI:C). We found selective reductions of PNNs in the PFC of polyI:C offspring which did not manifest until early adulthood. These deficits were not associated with changes in parvalbumin cell density, but a decrease in the percentage of parvalbumin cells surrounded by a PNN. Developmental expression of PNNs was also significantly altered in the amygdala of polyI:C offspring. Our results indicate MIA causes region specific developmental abnormalities in PNNs in the PFC of offspring. These findings confirm the polyI:C model replicates neuropathological alterations associated with schizophrenia and may identify novel mechanisms for cognitive and emotional dysfunction in the disorder

Cell-to-cell variability in troponin I phosphorylation in a porcine model of pacing-induced heart failure

We tested the hypothesis that myocardial contractile protein phosphorylation and the Ca2+ sensitivity of force production are dysregulated in a porcine model of pacing-induced heart failure (HF). The level of protein kinase A (PKA)-dependent cardiac troponin I (TnI) phosphorylation was lower in the myocardium surrounding the pacing electrode (pacing site) of the failing left ventricle (LV) than in the controls. Immunohistochemical assays of the LV pacing site pointed to isolated clusters of cardiomyocytes exhibiting a reduced level of phosphorylated TnI. Flow cytometry on isolated and permeabilized cardiomyocytes revealed a significantly larger cell-to-cell variation in the level of TnI phosphorylation of the LV pacing site than in the opposite region in HF or in either region in the controls: the interquartile range (IQR) on the distribution histogram of relative TnI phosphorylation was wider at the pacing site (IQR = 0.53) than that at the remote site of HF (IQR = 0.42; P = 0.0047) or that of the free wall of the control animals (IQR = 0.36; P = 0.0093). Additionally, the Ca2+ sensitivities of isometric force production were higher and appeared to be more variable in single permeabilized cardiomyocytes from the HF pacing site than in the healthy myocardium. In conclusion, the level of PKA-dependent TnI phosphorylation and the Ca2+ sensitivity of force production exhibited a high cell-to-cell variability at the LV pacing site, possibly explaining the abnormalities of the regional myocardial contractile function in a porcine model of pacing-induced HF

Using a sulfur-bearing silane to improve rubber formulations for potential use in industrial rubber articles

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Adhesion Science and Technology on 13/08/2012, available online: http://dx.doi.org/10.1080/01694243.The availability of the coupling agent bis (3-triethoxysilylpropyl)-tetrasulfide (TESPT) has provided an opportunity for enhancing the reinforcing capabilities of precipitated amorphous white silica in rubber. Styrene-butadiene rubber, synthetic polyisoprene rubber (IR), acrylonitrile-butadiene rubber, and natural rubber (NR) containing the same loading of a precipitated silica filler were prepared. The silica surface was pretreated with TESPT, which is a sulfur-bearing bifunctional organosilane to chemically bond silica to the rubber. The rubber compounds were subsequently cured by reacting the tetrasulfane groups of TESPT with double bonds in the rubber chains and the cure was optimized by adding sulfenamide accelerator and zinc oxide. The IR and NR needed more accelerators for curing. Surprisingly, there was no obvious correlation between the internal double bond content and the accelerator requirement for the optimum cure of the rubbers. Using the TESPT pretreated silanized silica was a very efficient method for cross-linking and reinforcing the rubbers. It reduced the use of the chemical curatives significantly while maintaining excellent mechanical properties of the cured rubbers. Moreover, it improved health and safety at work-place, reduced cost, and minimized damage to the environment because less chemical curatives were used. Therefore, TESPT was classified as "green silane" for use in rubber formulations

Complete Sequences of the Mitochondrial DNA of the Wild Gracilariopsis lemaneiformis and Two Mutagenic Cultivated Breeds (Gracilariaceae, Rhodophyta)

The complete mitochondrial DNA (mtDNA) of Gracilariopsis lemaneiformis was sequenced (25883 bp) and mapped to a circular model. The A+T composition was 72.5%. Forty six genes and two potentially functional open reading frames were identified. They include 24 protein-coding genes, 2 rRNA genes, 20 tRNA genes and 2 ORFs (orf60, orf142). There is considerable sequence synteny across the five red algal mtDNAs falling into Florideophyceae including Gr. lemaneiformis in this study and previously sequenced species. A long stem-loop and a hairpin structure were identified in intergenic regions of mt genome of Gr. lemaneiformis, which are believed to be involved with transcription and replication. In addition, the mtDNAs of two mutagenic cultivated breeds (“981” and “07-2”) were also sequenced. Compared with the mtDNA of wild Gr. lemaneiformis, the genome size and gene length and order of three strains were completely identical except nine base mutations including eight in the protein-coding genes and one in the tRNA gene. None of the base mutations caused frameshift or a premature stop codon in the mtDNA genes. Phylogenetic analyses based on mitochondrial protein-coding genes and rRNA genes demonstrated Gracilariopsis andersonii had closer phylogenetic relationship with its parasite Gracilariophila oryzoides than Gracilariopsis lemaneiformis which was from the same genus of Gracilariopsis

An ecological analysis of colorectal cancer incidence and mortality: Differences by sexual orientation

<p>Abstract</p> <p>Background</p> <p>Some have suggested gays and lesbians may carry a greater burden of colorectal cancer. To date, individual sexual orientation data are not available in cancer surveillance registries. This prevents an assessment of differences in colorectal cancer incidence and mortality by sexual orientation, using individual-level data.</p> <p>Methods</p> <p>We use an ecological approach to examine differences in colorectal cancer incidence and mortality by county-level sexual orientation data. From the Surveillance, Epidemiology and End Results (SEER) Program we obtain population-based surveillance data on colorectal cancer incidence and mortality from 1996 to 2004. We use Census 2000 data on same-sex partnered households, a proxy of sexual orientation, to derive county-level sexual orientation data. Using multiple regression models, we examined the county-level association of sexual minority density with colorectal cancer incidence and mortality.</p> <p>Results</p> <p>After controlling for race and SES, we identify a significant positive association between greater density of sexual minority men and women and colorectal cancer incidence. With respect to colorectal cancer mortality, we identify a positive association with density of sexual minority men, but not women.</p> <p>Conclusions</p> <p>In the absence of surveillance data on sexual minority individuals, ecological analyses provide estimates of associations at the aggregate level, thereby providing crucial information for follow-up studies.</p

Multiple Chronic Conditions: Prevalence, Health Consequences, and Implications for Quality, Care Management, and Costs

Persons with multiple chronic conditions are a large and growing segment of the US population. However, little is known about how chronic conditions cluster, and the ramifications of having specific combinations of chronic conditions. Clinical guidelines and disease management programs focus on single conditions, and clinical research often excludes persons with multiple chronic conditions. Understanding how conditions in combination impact the burden of disease and the costs and quality of care received is critical to improving care for the 1 in 5 Americans with multiple chronic conditions. This Medline review of publications examining somatic chronic conditions co-occurring with 1 or more additional specific chronic illness between January 2000 and March 2007 summarizes the state of our understanding of the prevalence and health challenges of multiple chronic conditions and the implications for quality, care management, and costs

Contribution of Cytochrome P450 and ABCB1 Genetic Variability on Methadone Pharmacokinetics, Dose Requirements, and Response

Although the efficacy of methadone maintenance treatment (MMT) in opioid dependence disorder has been well established, the influence of methadone pharmacokinetics in dose requirement and clinical outcome remains controversial. The aim of this study is to analyze methadone dosage in responder and nonresponder patients considering pharmacogenetic and pharmacokinetic factors that may contribute to dosage adequacy. Opioid dependence patients (meeting Diagnostic and Statistical Manual of Mental Disorders, [4th Edition] criteria) from a MMT community program were recruited. Patients were clinically assessed and blood samples were obtained to determine plasma concentrations of (R,S)-, (R) and (S)- methadone and to study allelic variants of genes encoding CYP3A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, and P-glycoprotein. Responders and nonresponders were defined by illicit opioid consumption detected in random urinalysis. The final sample consisted in 105 opioid dependent patients of Caucasian origin. Responder patients received higher doses of methadone and have been included into treatment for a longer period. No differences were found in terms of genotype frequencies between groups. Only CYP2D6 metabolizing phenotype differences were found in outcome status, methadone dose requirements, and plasma concentrations, being higher in the ultrarapid metabolizers. No other differences were found between phenotype and responder status, methadone dose requirements, neither in methadone plasma concentrations. Pharmacokinetic factors could explain some but not all differences in MMT outcome and methadone dose requirements