A case-control study of lung cancer among Vietnam veterans

Because of concerns among veterans over Agent Orange exposure, the Department of Veterans Affairs (VA) has conducted a series of studies of specific cancers among Vietnam veterans. Lung cancer is the topic of investigation in this report. The VA's Patient Treatment File (PTF) was used to identify 329 Vietnam era veterans with a diagnosis of lung cancer made between 1983 and 1990. The PTF is a computerized hospitalized database of inpatient records, including patients' demographic data, and diagnoses. A record is created for each patient discharged from any one of the VA's Medical Centers. Variables abstracted from the military record include education, race, branch of service, Military Occupational Specialty Code, rank, and units served within Vietnam. Two hundred sixty-nine controls were randomly selected from the PTF file of men hospitalized for a reason other than cancer. A second control group numbering 111 patients with colon cancer was also selected from the PTF file. Data were also gathered on exposure to Agent Orange through the location of each individual ground troop veteran's unit in relation to an area sprayed and the time elapsed since that area was sprayed. The crude odds ratio between service in Vietnam and lung cancer was of borderline significance (odds ratio = 1.39 with 95% confidence interval = 1.01-1.92). The relationship disappeared when the confounder year of birth was considered. We conclude from these data that there is no evidence of increased risk in lung cancer associated with service in Vietnam at this time.     

Partial replacement of carbon black with graphene in natural rubber/butadiene rubber based tire compound: Investigation of critical properties

Journal of Polymer Research - In this study, we prepared graphene oxide-based styrene/acrylic elastomeric disks (GSAE) from sugarcane bagasse/ferrocene (GO) and styrene/acrylic emulsion (SAE) to...     

Effect of fiber surface modification on the mechanical and water absorption characteristics of sisal/polyester composites fabricated by resin transfer molding

Sisal fibers were subjected to various chemical and physical modifications such as mercerization, heating at 100 °C, permanganate treatment, benzoylation and silanization to improve the interfacial bonding with matrix. Composites were prepared by these fibers as reinforcement, using resin transfer molding (RTM). The mechanical properties such as tensile, flexural and impact strength were examined. Mercerized fiber-reinforced composites showed 36% of increase in tensile strength and 53% in Young’s modulus while the permanganate treated fiber-reinforced composites performed 25% increase in flexural strength. However, in the case of impact strength, the treatment has been found to cause a reduction. The water absorption study of these composites at different temperature revealed that it is less for the treated fiber-reinforced composites at all temperatures compared to the untreated one. SEM studies have been used to complement the results emanated from the evaluation of mechanical properties.     

Socioeconomic status, neighborhood social conditions, and neural tube defects

OBJECTIVES: This study evaluated the contributions of lower socioeconomic status (SES) and neighborhood socioeconomic characteristics to neural tube defect etiology. The influence of additional factors, including periconceptional multivitamin use and race/ethnicity, was also explored. METHODS: Data derived from a case-control study of California pregnancies from 1989 to 1991. Mothers of 538 (87.8% of eligible) case infants/fetuses with neural tube defects and mothers of 539 (88.2%) nonmalformed infants were interviewed about their SES. Reported addresses were linked to 1990 US census information to characterize neighborhoods. RESULTS: Twofold elevated risks were observed for several SES indicators. Risks were somewhat confounded by vitamin use, race/ethnicity, age, body mass index, and fever but remained elevated after adjustment. A risk gradient was seen with increasing number of lower SES indicators. Women with 1 to 3 and 4 to 6 lower SES indicators had adjusted odds ratios of 1.6 (1.1-2.2) and 3.2 (1.9-5.4), respectively, compared with women with no lower SES indicators. CONCLUSIONS: Both lower SES and residence in a SES-lower neighborhood increased the risk of an neural tube defect-affected pregnancy, with risks increasing across a gradient of SES indicators.     

Influence of inhibitors on corrosion and anodic behaviour of different grades of aluminium in alkaline media

The electrochemical properties of different grades of aluminium are said to be dependent on the presence of minor amounts of iron and silicon impurities. This investigation aims mainly at addressing the influence of different inhibitors (e.g., sodium stannate, sodium citrate and calcium oxide combinations) on properties such as corrosion, anodic behaviour and anode utilization efficiency of different grades of aluminium in alkaline media.     

High‐performance nanocomposites based on arcylonitrile‐butadiene rubber with fillers of different particle size: Mechanical and morphological studies

Acrylonitrile‐butadiene rubber (NBR) nanocomposites with layered silicate (LS), calcium phosphate (CP), and titanium dioxide (TO) of different particle size were prepared in an open two‐roll mixing mill at different filler loading in presence of sulphur as vulcanizing agent. The layered silicate (LS) filled system showed outstanding enhancement in mechanical properties in comparison with nanocalcium phosphate (CP) and titanium dioxide (TO). The variations in properties can be attributed to the extent of intercalation/exfoliation, which was highly influenced by the filler size. The layered silicate filled system at 20 phr showed nearly 349% increase in tensile strength compared to pure NBR whereas an increase of 110% and 84% were shown by CP and TO filled systems respectively. The modulus enhancements were in the order of 200%, 63% and 22%, respectively compared to the unfilled system. The increase in tear resistance was in the order of 230%, 115%, and 41% respectively for the filled systems in comparison with unfilled NBR. The significant enhancements in mechanical properties were supported by the morphological analysis. POLYM. COMPOS., 31:1515–1524, 2010. © 2009 Society of Plastics Engineers     

Electrical properties of natural rubber nanocomposites: effect of 1-octadecanol functionalization of carbon nanotubes

This article reports the results of studies on the effect of 1-octadecanol (abbreviated as C18) functionalization of carbon nanotubes (CNT) on electrical properties of natural rubber (NR) composites. Dispersion of CNT in NR matrix was studied by transmission electron microscopy (TEM) and electrical resistivity measurements. Fourier transform infra red spectrometry (FTIR) indicates characteristic peaks for ether and hydrocarbon in the case of C18 functionalized CNT. Dielectric constant increases with respect to the filler loading for both unmodified and functionalized CNTs, the effect being less pronounced in the case of functionalized CNT due to its better dispersion in the matrix. Stress–strain plots suggest that the mechanical integrity of the NR/CNT composites, measured in terms of tensile strength, increases on C18 functionalization of the nanofiller. TEM reveals that the functionalization causes improvement in dispersion of CNT in NR matrix, which is corroborated by the increase in electrical resistivity in the case of the functionalized CNT/NR composites.     

Morphology,mechanical and thermal properties of nano-structured full IPNs based on polyisoprene and PMMA

Morphology, mechanical properties, thermal stability and gas transport behaviour of interpenetrating polymer networks (IPNs) based on PI/PMMA have been investigated using various techniques. Crosslinking level of both phases and concentration of PMMA were found to have noticeable effects on the compatibility of immiscible components during IPN formation. Effect of crosslinking was studied by preparing IPNs with varying amount of crosslinker concentration in each phase. Crosslinking of both phases facilitated deeper interpenetrations between both networks, and certain degree of compatibility is attained during IPN formation. Nanometre-sized domains were observed for highly crosslinked IPN. Lower concentration of PMMA was found to favour phase mixing more effectively than others. DSC curve of 65/35 IPN showed a broad transition arising from the α and β-relaxations of PMMA due to the higher flexibility attained by mixing with the highly mobile PI chains. The mechanical properties of the IPNs were correlated to the morphology of the system and 50/50 composition showed maximum mechanical properties among the studied compositions. Mode of mechanical failure, thermal stability and gas transport behaviour were also analysed. IPNs having nanometre-sized domains showed least gas permeability among the studied samples.     

Calcium phosphate incorporated poly(ethylene oxide)‐based nanocomposite electrolytes for lithium batteries. I. Ionic conductivity and positron annihilation lifetime spectroscopy studies

Nanocomposite polymer electrolytes (NCPEs) composed of poly(ethylene oxide), calcium phosphate [Ca₃(PO₄)₂], and lithium perchlorate (LiClO₄)/lithium bis(trifluoromethane sulfonyl)imide [LiN(CF₃SO₂)₂ or LiTFSI] in various proportions were prepared by a hot‐press method. The membranes were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetry–differential thermal analysis, ionic conductivity testing, and transference number studies. The free volume of the membranes was probed by positron annihilation lifetime spectroscopy at 30°C, and the results supported the ionic conductivity data. The NCPEs with LiClO₄ exhibited higher ionic conductivities than the NCPE with LiTFSI as a salt. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of phenol functionalization of carbon nanotubes on properties of natural rubber nanocomposites

This paper reports the results of studies on the effect of phenol functionalization of carbon nanotubes (CNTs) on the mechanical and dynamic mechanical properties of natural rubber (NR) composites. Fourier transform infrared spectrometry (FTIR) indicates characteristic peaks for ether and aromatic rings in the case of phenol functionalized CNT. Although differential scanning calorimetric (DSC) studies show no changes in the glass‐rubber transition temperature (T_g) of NR in the nanocomposites due to surface modification of CNT, dynamic mechanical studies show marginal shifting of T_g to higher temperature, the effect being pronounced in the case of functionalized CNT. Stress‐strain plots suggest an optimum loading of 5 phr CNT in NR formulations and the phenolic functionalization of CNT does not affect significantly the stress‐strain properties of the NR nanocomposites. The storage moduli register an increase in the presence of CNT and this increase is greater in the case of functionalized CNT. Loss tangent showed a decrease in the presence of CNT, and the effect is more pronounced in the case of phenol functionalized CNT. Transmission electron microscopy (TEM) reveals that phenol functionalization causes improvement in dispersion of CNT in NR matrix. This is corroborated by the increase in electrical resistivity in the case of phenol functionalized CNT/NR composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012