Effect of sulfur solvent on the properties of lead sulfide quantum dots

Colloidal quantum dots (QDs) of lead sulfide have been synthesized and investigated using octadecene and white spirit as a solvent for sulfur, varying the concentration of precursors and the temperature of the process. A method has been proposed for the synthesis of these QDs using anhydrous white spirit as a solvent at a temperature of 200° C, which made it possible to obtain polygonal nanoparticles with an average diameter of 2 to 3.2 nm with a minimum spread in size (± 10%). Solvent white spirit, which has a low limiting solubility for sulfur and creates specific conditions for the reaction of the formation of lead sulfide at a high temperature (200° C), provides good synthesis kinetics in solution, a relatively low crystallization rate and creates conditions for the passage of all stages of the process from the formation of embryos before the maturation of the crystals. In this process, crystals of sufficiently stable sizes and shapes are steadily formed. It follows that the crystals are not spherical, but possibly somewhat rod-shaped, since their sizes differ in two directions. It is also seen that the sizes of QDs obtained using different concentrations of a sulfur solution in white spirit and varying the temperature differ insignificantly, since the confidence intervals are quite large and overlap. In one direction, the crystal size varies from 2 to 3.5 nm, and in the other from 3.5 to 5 nm. It has been found that at low temperatures the rate of reaction and crystal formation slows down. In this case, the anisotropic growth of crystals is pronounced, and the histogram curves are clearly divided into two regions. As a result, the transformation of the cubic structure of the crystal into a hexapod is noted. An increase in the concentration of lead in the reaction medium leads to a slight acceleration of the synthesis of nanoparticles.

Poisons affecting the skin

All homes contain substances capable of causing serious injury if they come into contact with the skin. These substances include detergents, acids and alkalis found in many cleaning products, and petroleum distillates such as white spirit and petrol. Asphalt used in road surfacing can also cause local effects, particularly if it is still hot when contact occurs. The risk of effects on the skin from these chemicals is increased if decontamination in delayed. The method of decontamination will depend on the substance involved but in many cases simple bathing is sufficient. Removal of oily or greasy substances may require the use of a commercial degreaser and sticky material may need to be softened with oil or fat to facilitate removal. Decontamination after contact with corrosive substances may require prolonged and repeated water irrigation to ensure thorough removal. Another potential source of dermal injury in pets is exposure to psoralen-containing plants (such as hogweed, Heracleum spp.) in combination with ultraviolent light (sunlight) which can result in erythema, blistering and dermatitis. In this case, management is supportive with avoidance of sunlight.

Simultaneous determination of methanol, ethanol and isopropanol in human blood and white spirit samples

A simple and cost-effective method for simultaneous determination of methanol, ethanol, and isopropanol in human blood and white spirit samples using headspace gas chromatography coupled with flame ionization detection (HS-GC-FID) was developed and validated for clinical and toxicological purposes. In this study, the headspace sampling procedure was investigated, indicating optimized temperature of 70 °C in 20 min. Concentrations of target compounds were determined by internal standard (IS) method with acetonitrile as IS compound. A good resolution of chromatographic peaks was achieved. The linear ranges for all the compounds were from 1 to 500 mg/dL. Our method was validated with adequate accuracy (recovery > 98%) and precision (RSD < 0.1%) in whole human blood and white spirit samples. The limits of detection were below 0.5 mg/L for the three compounds. This method is easy to perform, making it suitable for routine analysis in clinical biochemistry and forensic laboratories.

Poisons affecting the skin

All homes contain substances capable of causing serious injury if they come into contact with the skin. These substances include detergents, acids and alkalis found in many cleaning products, and petroleum distillates, such as white spirit and petrol. Asphalt used in road surfacing can also cause local effects, particularly if it is still hot when contact occurs. The risk of these chemicals having an effect on the skin is increased if decontamination is delayed. The method of decontamination will depend on the substance involved, but in many cases simple bathing is sufficient. Removal of oily or greasy substances may require the use of a commercial degreaser and sticky material may need to be softened with oil or fat to allow removal. Decontamination after contact with corrosive substances may require prolonged and repeated water irrigation to ensure thorough removal. Another potential source of dermal injury in pets is exposure to psoralen-containing plants such as hogweed, Heracleum spp. in combination with ultraviolet light, which can result in erythema, blistering and dermatitis. In this case, management is supportive with an avoidance of sunlight.

Behavioral responses of freshwater bivalve mussel Unio pictorum to household derivatives of petroleum products

Petroleum products are one of the most common pollutants in water environments. Despite the fact that they do not belong to the mass of particularly dangerous toxic substances, their presence in the surface film, in dissolved form and sedimentary material adversely affects the life of marine and freshwater native flora and fauna. The list of sanitary and epidemiological rules and regulations “Zones of sanitary protection of water supply sources and drinking water pipes” specifies only general cartographic and design requirements. Thus, the purity and safety of fresh water used for irrigation and human activity without regular monitoring remains questionable. Bioelectronic monitoring of oil pollution in water sources using laboratory flow systems or submersible autonomous meters is becoming more and more relevant. Since field experiments with in these studies are in most cases impossible, it is logical to base on the results of laboratory experiments that are as close as possible to natural conditions. Under laboratory conditions, the possibility of automated detection of some common household derivatives of petroleum products in surface water sources is evaluated using a bioelectronic complex and bivalve freshwater mollusks (Unio pictorum) as part of environmental monitoring. The probability of actual detection of used petroleum products is estimated as “high” for diesel fuel, “medium” for kerosene and white spirit, and “low” for engine oil and brake fluid. The probability of detection as toxicants: “high” for diesel fuel, “medium” for white spirit, “low” for kerosene, engine oil and brake fluid.

The Natural History and Cultural History of La Source, 1866

At its debut in 1866, La Source already had it all: dagger-wielding Muslims dominating veiled women, a flower promising hybridity in a green ecology, and the death of the white spirit, the Source, recuperated as a force for regeneration. In the ballet’s botany, and its cultural thermodynamics, the plot becomes a fable of science and the performance its demonstration.

Association between occupational solvent exposure and cognitive performance in the French CONSTANCES study

ObjectiveThe objective of this study was to evaluate the association between occupational exposure to solvents and cognitive performance in middle-aged and early-ageing participants, taking into account the working environment.MethodsIn the French Cohorte des consultants des Centres d'examens de santé (CONSTANCES) cohort, 41 854 participants aged 45–69 years completed a self-reported, lifetime occupational exposure questionnaire. Exposure to solvents (gasoline for hand washing, trichloroethylene, white spirit, cellulosic thinner) was first considered as a binary variable (exposed/not exposed). We computed number of solvent types to which participants were exposed, solvent exposure time and delay since last exposure. Cognitive performance was assessed and analysed in reference to norms of neuropsychological battery previously established in CONSTANCES according to age, sex and education. Multiple linear and modified Poisson regression were used to estimate the associations between solvent exposure and cognitive performance adjusting for individual and environmental characteristics, and working conditions (night shift, repetitive and noisy work).ResultsMen had a greater risk of global cognitive impairment when they were exposed to gasoline (relative risk (RR)=1.12, 95% CI 1.03 to 1.22), white spirit (RR=1.14, 95% CI 1.05 to 1.25) or cellulosic thinner (RR=1.17, 95% CI 1.06 to 1.31) at the workplace, even after adjusting for confounders. Women exposed to white spirit or exposed for more than 20 years had poorer global cognitive performance.ConclusionThese findings strengthen our understanding of the detrimental effect of solvent exposure on cognitive health not only in men but also in women for the first time, in a large general population middle-aged and early-ageing sample from France, taking into account working conditions.