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Reprotoxic and Endocrine Substances
Published in Małgorzata Pośniak, Emerging Chemical Risks in the Work Environment, 2020
Katarzyna Miranowicz-Dzierżawska
2-Methoxyethanol is used in the chemical, metallurgical, machine, electronics, furniture, textiles, leather, and cosmetics industries. It is a solvent for cellulose acetate and nitrocellulose, natural and synthetic resins, chlorinated rubber, paints, varnishes, polishes, and inks. It is also used in the production of photographic films and in photolithographic processes (e.g. in the manufacturing of semiconductors). It is also used as a fixative in the production of perfumes, liquid soaps, and other cosmetics. Negative effects of 2-methoxyethanol on reproductive health and fetal development have been shown in epidemiological studies. Exposure of males to 2-methoxyethanol in concentrations of 17–26 mg/m3 caused a significant decrease in the size of the testicles. In women exposed to 2-methoxyethanol in the first trimester of pregnancy, the risk of spontaneous miscarriages was 2–3 times higher. In newborns, an increase in the incidence of ossification disorders, congenital malformations of the ribs and the cardiovascular system, cleft palate, and multiple birth defects were noted [Szymańska and Bruchajzer 2010].
Cleaning workers’ exposure to volatile organic compounds and particulate matter during floor polish removal and reapplication
Published in Journal of Occupational and Environmental Hygiene, 2019
Joonas Ruokolainen, Marko Hyttinen
Glycol ethers are widely used in different chemicals, for example, in paints, lacquers, cleaning solutions (especially floor polishes and polish removers), degreasers, varnish removers, and hydraulic fluids.[4,10–13] Due to the vast use of glycol ethers there are multiple occupations where exposure to glycol ethers occurs, for example, painters, printers (silk-screen, offset, and stamping printers), cleaning workers, graffiti removers, textile and dying industry, workers handling fuel.[4,13,14] Repeated exposure to glycol ethers can lead to contact dermatitis.[13] Previously used glycol ethers (2-alkoxyethanols, mainly 2-methoxyethanol and 2-ethoxyethanol) were found to cause multiple adverse health effects, including hematological effects, oligospermia and azoospermia, reproductive problems, and immunotoxic effects, therefore they have been substituted with less hazardous solvents with redesigned chemical structures.[10] The exposure to gaseous EGBE can cause irritation of eyes, nose, and throat.[12] Also, EGBE has hematological effects, for example, it has been linked to reticulocytosis in screen-printing workers.[12,15] A study by Rella et al.[16] indicated that cleaning related EGBE caused complaints of poor indoor air quality. EGPE has been reported causing contact urticarial.[17,18]
Electro-optical performance of liquid crystal device based on Al-doped SnO fabricated by sol-gel process
Published in Liquid Crystals, 2020
Jong Hoon Won, Ju Hwan Lee, Dong Hyum Kim, Dong Wook Lee, Dae-Hyun Kim, Hae-Chang Jeong, Byeong-Yun Oh, Jeong Min Han, Dae-Shik Seo
The blue (simulated) and red (experimental) curves are nearly identical at annealing temperatures above 200°C, indicating that the LC alignment was stable. In contrast, there is a difference between the two curves at an annealing temperature of 100°C, indicating that the LC molecules were randomly aligned. The boiling point of the solvent 2-methoxyethanol is 125°C, which is higher than the annealing temperature of 100°C. Thus, some residual solvent remains on the surface rather than evaporating completely, thereby prohibiting the formation of a stable pre-tilt angle on the surfaces. In contrast, uniform and stable LC alignment were achieved at an annealing temperature of 200°C.
Cu2ZnSnS4 films with Cu-poor composition prepared by spin coating from a nontoxic methanol-based solution: the effect of annealing temperature
Published in Journal of Asian Ceramic Societies, 2020
Hall-effect and resistivity measurements were performed on the as-grown and annealed films, at room temperature, by using the four-probe technique with the van der Pauw configuration. All the films showed p-type conductivity, as expected. The concentration, p, and mobility, µ, of the free holes and the resistivity, ρ, of the films were determined and the results are illustrated in Figure 5. For the as-grown film, p = 8.4 × 1015 cm−3, µ = 11.7 cm2/V-s, and ρ = 63.7 Ωcm were measured. The value of p increased from 1.97 × 1016 cm−3 to 4.3 × 1018 cm−3 and ρ decreased from 58.8 Ω.cm to 0.04 Ωcm almost systematically as the annealing temperature was raised from 350 °C to 550 °C. The value of µ for the annealed films varied in the range of 1.2–136 cm2/V-s, as seen in Figure 5. The systematic increase of p with the annealing temperature is apparently due to the increase in the concentration of the uncompensated ionized acceptor-type shallow defects, as the result of thermal activation. Copper vacancy (VCu) and CuZn (Cu occupies Zn site) defects are two shallow acceptor-type native defects in CZTS with the ionization energies of 20 meV and 100–120 meV, respectively [32]. Despite the higher ionization energy of CuZn defect, its contribution to p-type conductivity of CZTS is not negligible as the result of its higher concentration [33]. Different scattering mechanisms can be responsible for the variation of hole mobility with the annealing temperature as is shown in Figure 5. The initial decrease of µ with the increase of annealing temperature is attributed to the dominant scattering mechanism of holes by ionized (negatively charged) acceptor-type defects whose concentration increases with the annealing temperature. For the annealing temperatures above ~400 °C, µ starts to increase. This is likely due to the dominant effect of holes scattering by the neutral defects such as crystallite boundaries and dislocation density which decrease with the increase of annealing temperature. The variations of p and µ with annealing temperature yields a systematic decrease of resistivity with the increase of annealing temperature. Figure 5 indicates that CZTS films with a desirable hole concentration or hole mobility can be synthesized, for different applications, by a brief annealing process at a particular temperature in the range of 350–550 °C. The effect of annealing, in the same temperature range (350–550 °C), on transport properties of films spin-coated from a different solvent (2-methoxyethanol) and stabilizer (mono-ethanolamine) has also been reported [16,20]. The reported values varied in the range of p = (0.19–21)×1018 cm−3, µ = (17.5–53.5) cm2/V-s, and ρ = (0.09–0.73) Ω.cm [16], and p = (0.37–6.2)×1018 cm−3, µ = (0.08–0.5) cm2/V-s, and ρ = (10–33.9) Ω.cm [20]. For comparison, the results of our study along with those for CZTS films prepared by vacuum-based techniques are listed in Table 2. It is evident that the transport parameters of Cu-poor films are comparable with those for the films with other compositions.