Influence of Graphene Type and Content on Friction and Wear of Silicon Carbide/Graphene Nanocomposites in Aqueous Environment.

Two different types of graphene materials were used as functional nanofillers for the mechanical and tribological improvement of silicon carbide/graphene nanocomposites. On the one hand is thermally reduced graphite oxide (TRGO) reduced at three different temperatures, and on the other hand is graphene made of three different organic precursors, which were directly coated on silicon carbide (SiC) platelets (GSiC). Additionally, benchmark materials were also used as carbon fillers. The SiC/graphene nanocomposites with 2 wt% filler content were manufactured by pressureless sintering (PLS). Some composites were produced with higher graphene contents of 4% and 8% and sintered by spark plasma sintering (SPS). Microstructural analyses were conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Underwater lubrication, the SP sintered TRGO and GSiC materials with high graphene content have shown the most promising tribological performance. Furthermore, the reduced size of the homogeneously distributed nanoparticles promotes the formation of surface states, which improve the friction and wear properties.

Preparation and Properties of Layered SiC-Graphene Composites for EDM.

Three and five-layered silicon carbide-based composites containing 0, 5, and 15 wt.% of graphene nanoplatelets (GNPs) were prepared with the aim to obtain a sufficiently high electrical conductivity in the surface layer suitable for electric discharge machining (EDM). The layer sequence in the asymmetric three-layered composites was SiC/SiC-5GNPs/SiC-15GNPs, while in the symmetric five-layered composite, the order of layers was SiC-15GNPs/SiC-5GNPs/SiC/SiC-5GNPs/SiC-15GNPs. The layered samples were prepared by rapid hot-pressing (RHP) applying various pressures, and it was shown that for the preparation of dense 3- or 5-layered SiC/GNPs composites, at least 30 MPa of the applied load was required during sintering. The electrical conductivity of 3-layered and 5-layered composites increased significantly with increasing sintering pressure when measured on the SiC surface layer containing 15 wt.% of GNPs. The increasing GNPs content had a positive influence on the electrical conductivity of individual layers, while their instrumented hardness and elastic modulus decreased. The scratch tests confirmed that the materials consisted of well-defined layers with straight interfaces without any delamination, which suggests good adhesion between the individual layers.

Estimated hospital costs associated with preventable health care-associated infections if health care antiseptic products were unavailable.

OBJECTIVES: Health care-associated infections (HAIs) pose a significant health care and cost burden. This study estimates annual HAI hospital costs in the US avoided through use of health care antiseptics (health care personnel hand washes and rubs; surgical hand scrubs and rubs; patient preoperative and preinjection skin preparations). METHODS: A spreadsheet model was developed with base case inputs derived from the published literature, supplemented with assumptions when data were insufficient. Five HAIs of interest were identified: catheter-associated urinary tract infections, central line-associated bloodstream infections, gastrointestinal infections caused by Clostridium difficile, hospital- or ventilator-associated pneumonia, and surgical site infections. A national estimate of the annual potential lost benefits from elimination of these products is calculated based on the number of HAIs, the proportion of HAIs that are preventable, the proportion of preventable HAIs associated with health care antiseptics, and HAI hospital costs. The model is designed to be user friendly and to allow assumptions about prevention across all infections to vary or stay the same. Sensitivity analyses provide low- and high-end estimates of costs avoided. RESULTS: Low- and high-end estimates of national, annual HAIs in hospitals avoided through use of health care antiseptics are 12,100 and 223,000, respectively, with associated hospital costs avoided of US$142 million and US$4.25 billion, respectively. CONCLUSION: The model presents a novel approach to estimating the economic impact of health care antiseptic use for HAI avoidance, with the ability to vary model parameters to reflect specific scenarios. While not all HAIs are avoidable, removing or limiting access to an effective preventive tool would have a substantial impact on patient well-being and infection costs. HAI avoidance through use of health care antiseptics has a demonstrable and substantial impact on health care expenditures; the costs here are exclusive of administrative penalties or long-term outcomes for patients and caregivers such as lost productivity or indirect costs.

Effect of spironolactone in resistant arterial hypertension: a randomized, double-blind, placebo-controlled trial (ASPIRANT-EXT).

This study was designed to assess the effect of the addition of low-dose spironolactone on blood pressure (BP) in patients with resistant arterial hypertension. Patients with office systolic blood pressure (SBP) >140 mm Hg or diastolic blood pressure (DBP) >90 mm Hg despite treatment with at least 3 antihypertensive drugs, including a diuretic, were enrolled in this double-blind, placebo-controlled, multicentre trial. One hundred sixty-one patients in outpatient internal medicine departments of 6 hospitals in the Czech Republic were randomly assigned to receive 25 mg of spironolactone (N = 81) or a placebo (N = 80) once daily as an add-on to their antihypertensive medication, using simple randomization. This study was registered with ClinicalTrials.gov, number NCT00524615. A nalyses were done with 150 patients who finished the follow-up (74 in the spironolactone and 76 in the placebo group). At 8 weeks, BP values were decreased more by spironolactone, with differences in mean fall of SBP of -9.8, -13.0, -10.5, and -9.9 mm Hg (P < 0.001 for all) in daytime, nighttime, and 24-hour ambulatory BP monitoring and in the office. The respective DBP differences were -3.2, -6.4, -3.5, and -3.0 mm Hg (P = 0.013, P < 0.001, P = 0.005, and P = 0.003). Adverse events in both groups were comparable. The office SBP goal <14 mm Hg at 8 weeks was reached in 73% of patients using spironolactone and 41% using placebo (P = 0.001). Spironolactone in patients with resistant arterial hypertension leads to a significant decrease of both SBP and DBP and markedly improves BP control.

Effect of spironolactone in patients with resistant arterial hypertension in relation to age and sex: insights from the aspirant trial.

BACKGROUND: There are currently limited data on whether the effect of spironolactone in patients with resistant arterial hypertension depends on age and sex. METHODS: Patients with an office systolic blood pressure (BP)>140 mmHg or diastolic BP>90 mmHg, despite treatment with at least 3 antihypertensive drugs including a diuretic, were randomly assigned to receive spironolactone or a placebo for 8 weeks in a double-blind, placebo-controlled, multicentre trial (ASPIRANT). RESULTS: Analyses were done on 55 patients treated with spironolactone and 56 patients treated with placebo. Significant reductions of office systolic BP (-8.9±6.7 mmHg, P=0.012), 24-h ABPM systolic BP (-7.9±7.2 mmHg, P=0.032) and ABPM day-time systolic BP (-7.5±7.1 mmHg) after 8 weeks of spironolactone treatment, compared to placebo, were only observed in patients with a median age>62 years. The office and ABPM systolic BP reductions in patients aged ≤62 years and diastolic BP reductions by spironolactone in both age groups were not significant compared to placebo. Women tended to have a nonsignificantly higher reduction in systolic BP with spironolactone treatment, and there was no difference in diastolic BP reduction between women and men. CONCLUSIONS: Spironolactone only leads to a reduction of systolic BP in older patients with resistant arterial hypertension aged >62 years, and is effective to a similar extent in men and women.

The effect of spironolactone in patients with resistant arterial hypertension in relation to baseline blood pressure and secondary causes of hypertension.

AIMS: There are currently limited data about whether the effect of spironolactone in patients with resistant arterial hypertension depends on baseline blood pressure and the presence of a secondary cause of hypertension. METHODS: Patients with office systolic blood pressure (BP) >140 mmHg or diastolic BP >90 mmHg, despite treatment with at least 3 antihypertensive drugs including a diuretic, were randomly assigned to receive spironolactone or a placebo for 8 weeks in a double-blind, placebo-controlled, multicentre trial (ASPIRANT). RESULTS: Analyses were done with 55 patients treated with spironolactone. The degree of BP reduction after 8 weeks of spironolactone treatment did not differ significantly between the three tertiles of baseline systolic BP and patients with and without a secondary cause of hypertension. The reduction of office systolic, office diastolic BP and office pulse pressure was significantly lower in the highest tertile with baseline diastolic BP > 97 mmHg. CONCLUSIONS: Spironolactone treatment is effective to a similar extent both in patients with and without a secondary cause of hypertension and regardless of the baseline value of systolic BP. Less effect of spironolactone was found in patients with the highest baseline diastolic BP.

Addition of spironolactone in patients with resistant arterial hypertension (ASPIRANT)--study protocol.

BACKGROUND: There is currently limited data on which drug should be used to improve blood pressure control in patients with resistant hypertension. Recent observational trials reported spironolactone as having good effects. This study is designed to assess the effect of the addition of 25 mg of spironolactone on blood pressure (BP) in patients with resistant arterial hypertension. METHODS: Patients with office systolic BP > 140 mmHg or diastolic BP > 90 mmHg despite treatment with at least 3 antihypertensive drugs including a diuretic, are enrolled in this double-blind, placebo-controlled, multicentre trial. Patients are randomly assigned to receive spironolactone or a placebo at a ratio of 1:1 by the method of simple randomisation. Our primary endpoints are to show a statistically significant difference in the fall of mean day-time systolic and diastolic BP by ambulatory blood pressure monitoring (ABPM), between the spironolactone and placebo groups, after 8 weeks of treatment. Secondary outcomes are changes of serum potassium, natrium, creatinine, body weight, casual blood pressure in office, difference in the fall of mean night-time and 24-hour ABPM BP and treatment response depending on different baseline levels of aldosterone and aldosterone/PRA ratio. DISCUSSION: If spironolactone proves effective, it might become the standard of treatment in patients with resistant arterial hypertension.

Addition of spironolactone in patients with resistant arterial hypertension (ASPIRANT): a randomized, double-blind, placebo-controlled trial.

There is currently limited data on which drug should be used to improve blood pressure (BP) control in patients with resistant hypertension. This study was designed to assess the effect of the addition of 25 mg of spironolactone on BP in patients with resistant arterial hypertension. Patients with office systolic BP >140 mm Hg or diastolic BP >90 mm Hg despite treatment with at least 3 antihypertensive drugs, including a diuretic, were enrolled in this double-blind, placebo-controlled, multicenter trial. One hundred seventeen patients were randomly assigned to receive spironolactone (n=59) or a placebo (n=58) as an add-on to their antihypertensive medication, by the method of simple randomization. Analyses were done with 111 patients (55 in the spironolactone and 56 in the placebo groups). At 8 weeks, the primary end points, a difference in mean fall of BP on daytime ambulatory BP monitoring (ABPM), between the groups was -5.4 mm Hg (95%CI -10.0; -0.8) for systolic BP (P=0.024) and -1.0 mm Hg (95% CI -4.0; 2.0) for diastolic BP (P=0.358). The APBM nighttime systolic, 24-hour ABPM systolic, and office systolic BP values were significantly decreased by spironolactone (difference of -8.6, -6.6, and -6.5 mm Hg; P=0=0.011, 0.004, and 0.011 [corrected]), whereas the fall of the respective diastolic BP values was not significant (-3.0, -1.0, and -2.5 mm Hg; P=0.079, 0.405, and 0.079). The adverse events in both groups were comparable. In conclusion, spironolactone is an effective drug for lowering systolic BP in patients with resistant arterial hypertension.

Environmental properties and aquatic hazard assessment of anionic surfactants: physico-chemical, environmental fate and ecotoxicity properties.

This paper summarizes the environmental hazard assessment of physicochemical properties, environmental fate and behavior and the ecotoxicity of a category of 61 anionic surfactants (ANS), comprised of alkyl sulfates (AS), primary alkane sulfonates (PAS) and alpha-olefin sulfonates (AOS) under the High Production Volume Chemicals Program of the Organisation for Economic Co-operation and Development (OECD). The most important common structural feature of the category members examined here is the presence of a predominantly linear aliphatic hydrocarbon chain with a polar sulfate or sulfonate group, neutralized with a counter-ion. The hydrophobic hydrocarbon chain (with a length between C(8) and C(18)) and the polar sulfate or sulfonate groups confer surfactant properties and enable the commercial use of these substances as anionic surfactants. The close structural similarities lead to physico-chemical properties and environmental fate characteristics which follow a regular pattern and justify the applied read-across within a category approach. Common physical and/or biological properties result in structurally similar breakdown products and are, together with the surfactant properties, responsible for similar environmental behavior. The structural similarities result in the same mode of ecotoxic action. Within each of the three sub-categories of ANS the most important parameter influencing ecotoxicity is the varying length of the alkyl chain. Although the counter-ion may also influence the physico-chemical properties, there is no indication that it significantly affects chemical reactivity, environmental fate and behavior or ecotoxicity of these chemicals. Deduced from physico-chemical and surfactancy properties, the main target compartment for the substances of the ANS category is the hydrosphere. They are quantitatively removed in waste water treatment plants, mainly by biodegradation. Quantitative removal in biological treatment plants is reflected by low AS concentrations measured in effluents of waste water treatment plants (mostly below 10 µg/L). In addition, bioaccumulation of ANS does not exceed regulatory triggers based upon experimental data. A considerable number of reliable aquatic toxicity data for the whole ANS category are available, including chronic and subchronic data for species of all trophic levels. Based upon the highest quality data in hand, there appears to be no singularly most sensitive trophic level in tests on the toxicity of alkyl sulfates, with a large degree of overlap among algae, invertebrates and fish. Algae proved to be more variable in sensitivity to alkyl sulfate exposure compared to fish and daphnia. The key study for the aquatic hazard assessment is a chronic test on Ceriodaphnia dubia, which covers a range of the alkyl chain length from C(12) to C(18). A parabolic response was observed, with the C(14) chain length being the most toxic (7d-NOEC=0.045 mg/L). Responses of aquatic communities to C(12) AS and C(14-15) AS have been studied in high quality stream mesocosm studies containing a broad range of species and ecological interactions. These studies are regarded as a better approximation to reality when extrapolating to the environment. The 56-d chronic NOEC for C(12) AS and C(14-15) AS were 0.224 and 0.106 mg/L, respectively, based on integrated assessments of periphyton (algal, bacterial and protozoan) and invertebrate communities. Taking into account the rapid biodegradation of the ANS compounds as well as the low concentrations measured in different environmental compartments, this category of surfactants is of low concern for the environment.

Toxicological properties and risk assessment of the anionic surfactants category: Alkyl sulfates, primary alkane sulfonates, and α-olefin sulfonates.

The category of the anionic surfactants (ANS) consisting of 46 alkyl sulfates, 6 primary alkane sulfonates, and 9 α-olefin sulfonates has been assessed under the high production volume (HPV) chemicals program of the Organisation for Economic Cooperation and Development (OECD) in 2007. In this review the toxicological properties of these chemicals are summarized. The chemicals of this category are used predominantly in detergents, household cleaning products, and cosmetics. These chemicals show low acute and repeat dose toxicity. There was no evidence of genetic or reproductive toxicity, or carcinogenicity. There also was no indication for sensitizing properties. Skin and eye irritating effects in consumers are not to be expected. For consumers, the calculated body burden is about 10,000 times lower than the lowest NOAEL value in experimental animals, so that adverse effects caused by substances of the ANS category can be excluded.

Environmental risk assessment of hydrotropes in the United States, Europe, and Australia.

An environmental assessment of hydrotropes was conducted under the Organisation for Economic Co-operation and Development (OECD) Screening Information Data Sets (SIDS) for High Production Volume (HPV) Program via the Global International Council of Chemical Associations (ICCA) Hydrotropes Consortium. The assessment and its conclusions were presented at a meeting of the OECD member countries in Washington, DC in 2005. The SIDS Initial Assessment Report (SIAR) was accepted by the membership. Their conclusion was "The chemicals in this [hydrotropes] category are of low priority for further work because of their low hazard profile." Hydrotropes are used to solubilize the water-insoluble ingredients of cleaning and personal care products including, for example, powder and liquid laundry detergents, hard-surface cleaners, machine dishwashing rinse aids, hand dishwashing liquids, body washes, shampoos, hair conditioners, and liquid hand and face soaps. Global production equals approximately 46 500 metric tons, a little more than half of which is used in the United States. The 8 chemicals accounted for in the "hydrotropes category" include ammonium, Ca, K, and Na salts that are described by 10 Chemical Abstract Service (CAS) registration numbers. The 8 chemical entities are generally comparable and predictable in their chemical behavior and that measured and/or modeled data for members from one subgroup can be applied to other subgroups and to the hydrotropes category as a whole. The assessment is based on a search for and evaluation of available data on physical­chemical properties, biodegradability, removal by wastewater treatment, and aquatic toxicity. Reliable ecotoxicity and environmental fate data were found for selected members of the category. Partitioning, once released into the environment, and exposure in surface waters were modeled for consumer use and manufacturing scenarios relevant to the United States, Europe, and Australia. The models indicate 99+% of the hydrotropes will partition to water. Furthermore, given the low potential for hydrotropes reaching the terrestrial environment and their lack of persistence or bioaccumulation, the focus of the assessment is on the aquatic environment, specifically the water compartment. Aquatic risks were assessed in each scenario using what is referred to as the PEC/PNEC ratio. The modeled predicted environmental concentration (PEC), accounting for volume released and wastewater treatment, is divided by the predicted no effect concentration (PNEC) derived from the aquatic toxicity tests. The closest a predicted environmental concentration came to the toxicity threshold is 0.125 (or 12.5% of the no effect concentration) and that is for a hypothetical manufacturing facility that produces the entire annual volume of hydrotropes and discharges to a small (10%ile) stream under low flow (7Q10) conditions. PEC/PNEC ratios were considerably smaller for consumer use scenarios. The ratios were 0.0002 for a low flow (7Q10) stream scenario in the United States, 0.026 to 0.089 for regional and local water bodies, respectively, in Europe, and 0.004 to 0.036 for oceans and rivers, respectively, in Australia. In conclusion, aquatic hazard levels are not expected to be reached under exaggerated conditions of manufacture or normal consumer use of hydrotropes. Hydrotropes are neither persistent nor bioaccumulative in the environment.

High production volume chemical amine oxides [C8-C20] category environmental risk assessment.

An environmental assessment of amine oxides has been conducted under the OECD SIDS High Production Volume (HPV) Program via the Global International Council of Chemical Associations (ICCA) Amine Oxides Consortium. Amine oxides are primarily used in conjunction with surfactants in cleaning and personal care products. Given the lack of persistence or bioaccumulation, and the low likelihood of these chemicals partitioning to soil, the focus of the environmental assessment is on the aquatic environment. In the United States, the E-FAST model is used to estimate effluent concentrations in the United States from manufacturing facilities and from municipal facilities resulting from consumer product uses. Reasonable worst-case ratios of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) range from 0.04 to 0.003, demonstrating that these chemicals are a low risk to the environment.

Human health risk assessment of long chain alcohols.

Representative chemicals from the long chain alcohols category have been extensively tested to define their toxicological hazard properties. These chemicals show low acute and repeat dose toxicity with high-dose effects (if any) related to minimal liver toxicity. These chemicals do not show evidence of activity in genetic toxicity tests or to the reproductive system or the developing organism. These chemicals also are not sensitizers. Irritation is dependant on chain length; generally, alcohols in the range C(6-)C(11) are considered as irritant, intermediate chain lengths (C(12-)C(16)) alcohols are considered to be mild irritants and chain lengths of C(18) and above are considered non-irritants. These chemicals are broadly used across the consumer products industry with highest per person consumer exposures resulting from use in personal care products. Margins of exposure adequate for the protection of human health are documented for the uses of these chemicals.

An overview of hazard and risk assessment of the OECD high production volume chemical category--long chain alcohols [C(6)-C(22)] (LCOH).

This review summarizes the findings of the assessment report for the category, long chain alcohols (LCOH) with a carbon chain length range of C(6)-C(22) covering 30 substances, and >1.5million tonnes/year consumed globally. The category was evaluated under the Organization for Economic Co-operation and Development (OECD) high production volume chemicals program in 2006. The main findings of the assessment include: (1) no unacceptable human or environmental risks were identified; (2) these materials are rapidly and readily biodegradable; (3) a parabolic relationship was demonstrated between carbon chain length and acute and chronic aquatic toxicity; (4) category-specific (quantitative) structure-activity relationships were developed enabling prediction of properties across the entire category; (5) LCOH occur naturally in the environment in an equilibrium between synthesis and degradation; (6) industry coming together and sharing resources results in minimizing the need for additional animal tests, produces cost savings, and increases scientific quality of the assessment.