Silver-Loaded Chabazite in Ethanol-to-Hydrocarbon Process-Operando FT-IR and UV-Vis Spectroscopic Studies.

The ethanol dehydration process is studied regarding protonic and Ag-loaded chabazite zeolite in advanced FT-IR and UV-vis operando spectroscopic studies with simultaneous mass spectroscopy and gas chromatography analyses of products. The spectroscopic investigation provides information on the species formed on the surface of catalysts, while mass spectrometry and gas chromatography methods identify the desorbed products. These studies are also supported by spectroscopic, chromatographic, and thermogravimetric analyses of coke species formed over the catalyst's surface during ethanol conversion. The Ag-chabazite catalyst shows higher selectivity for ethylene and propylene; the slower formation of coke species; and, thus, a longer lifetime.

Anaerobic bacteria in wastewater treatment plant.

PURPOSE: The objective of this study was to assess exposure to anaerobic bacteria released into air from sewage and sludge at workplaces from a wastewater treatment plant (WWTP). METHODS: Samples of both sewage and sludge were collected at six sampling points and bioaerosol samples were additionally collected (with the use of a 6-stage Andersen impactor) at ten workplaces covering different stages of the technological process. Qualitative identification of all isolated strains was performed using the biochemical API 20A test. Additionally, the determination of Clostridium pathogens was carried out using 16S rRNA gene sequence analysis. RESULTS: The average concentration of anaerobic bacteria in the sewage samples was 5.49 × 104 CFU/mL (GSD = 85.4) and in sludge-1.42 × 106 CFU/g (GSD = 5.1). In turn, the average airborne bacterial concentration was at the level of 50 CFU/m3 (GSD = 5.83) and the highest bacterial contamination (4.06 × 103 CFU/m3) was found in winter at the bar screens. In total, 16 bacterial species were determined, from which the predominant strains belonged to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. The analysis revealed that mechanical treatment processes were responsible for a substantial emission of anaerobic bacteria into the air. In both the sewage and air samples, Clostridium perfringens pathogen was identified. CONCLUSIONS: Anaerobic bacteria were widely present both in the sewage and in the air at workplaces from the WWTP, especially when the technological process was performed in closed spaces. Anaerobic bacteria formed small aggregates with both wastewater droplets and dust particles of sewage sludge origin and as such may be responsible for adverse health outcomes in exposed workers.

[Assessment of fungal aerosol exposure at selected workplaces contaminated with organic dust of different origin]. / Ocena narazenia na aerozol grzybowy na wybranych stanowiskach pracy zanieczyszczonych pylem organicznym o róznym pochodzeniu.

BACKGROUND: In recent years, the number of people suffering from diseases caused by fungi has been increasing. However, knowledge of the biodiversity of fungal pathogens in the work environment is still insufficient. The aim of this work was to evaluate the exposure to fungi being disseminated in the air of workplaces contaminated with organic dust of plant and animal origin. MATERIAL AND METHODS: Bioaerosol samples were collected at 3 occupational settings (poultry farm, biomass burning power plant and wastewater treatment plant) using button samplers. Quantitative and qualitative analysis of fungal aerosol was conducted by employing macro- and microscopic methods. Selected strains were then studied by polymerase chain reaction (PCR) using srodointernal transcribed spacers (ITS): ITS1-ITS2, ITS3-ITS4 and ITS1-ITS4 primer pairs. RESULTS: Average concentrations of fungal aerosol at workplaces ranged 1.2×102-2.1×106 cfu/m3. The highest fungal concentrations were recorded in the poultry farm, while the lowest were noted at the wastewater treatment plant. Aspergillus fumigatus was a predominant component of the mycobiota in the power plant and wastewater treatment plant. Almost 100% identification agreement of this pathogen between the traditional and molecular method was noted. CONCLUSIONS: The fungal concentrations in poultry farms exceeded the Polish proposal for the threshold limit value (5×104 cfu/m3). The results of the study demonstrate a high compatibility of A. fumigatus' identification using the traditional and molecular methods. Taking into account the fact, that a long term exposure to A. fumigatus conidia at workplaces may result in numerous health complaints, the use of proper protective equipment by workers must be a standard procedure. Med Pr 2018;69(3):269-280.

Monitoring of bacterial pathogens at workplaces in power plant using biochemical and molecular methods.

PURPOSE: The aim of this study was to characterize the ways of spreading of the most common bacterial species isolated from workers as well as from the air and raw materials at the workplaces in power plant utilizing biomass sources. To monitor microbial transmission and identify the source of contamination in the working environment, a combination of molecular and biochemical methods was applied. METHODS: The study was carried out at workplaces in power plant utilizes biomass as a main fuel source. At each of the studied workplaces, bioaerosol particles were collected on sterile Teflon filters using personal conical inhalable samplers (CIS), and biomass samples (straw pellets and briquettes, corn briquettes, sunflower pellets and wood chips) were directly taken from their storage places. Simultaneously with that, the swab samples from the hands of ten workers and their used respiratory masks (of FFP2 class) were also collected after the work shift to evaluate individual workers' microbial contamination. In all collected samples, total bacterial concentrations were assessed and the most common microbial isolates were identified to the species level using both biochemical (API tests) and molecular polymerase chain reaction (PCR), followed by random amplification of polymorphic DNA (RAPD) typing methods. RESULTS: The mean concentrations of culturable bacteria in the air and in biomass samples at the studied workplaces were high, i.e. 1.2 × 106cfu/m3 and 3.8 × 104cfu/g, respectively. The number of bacteria in the swab and mask samples also reached a high level of 1.4 × 104 cfu/ml and 1.9 × 103 cfu/cm2, respectively. Among the most frequently isolated microorganisms from all types of samples were Gram-positive bacteria of the genus Bacillus and Staphylococcus xylosus. 37 bacterial strains belonging to the genus Bacillus (B. licheniformis 8, B. pumilus 15 and B. subtilis 4) and Staphylococcus (10) were genotyped by the RAPD-PCR method. Based on RAPD-PCR analyses, the genomic similarity among 19 Bacillus strains isolated from biomass, air, protective mask and hand samples as well as 6 S. xylosus strains isolated from air, mask and hand samples exceeded 80%. CONCLUSION: This study demonstrated that biomass is the primary source of bacteria at power plant workplaces. These results also revealed that biomass-associated bacteria can be easily transferred to workers' hands and mask during their routine activities. To improve health protection at the workplaces, adequate training courses on hand hygiene and how to use and remove respiratory masks correctly for workers should be introduced as a key element of the prevention strategy. From the occupational point of view, the PCR-based methods seem to be an efficient tool for a fast and precise typing of bacterial strains isolated from different sources in the occupational environment. Such methods may help to implement appropriate prophylactic procedures and minimize transmission of infectious agents at workplaces.

[Bacterial and fungal aerosols in the work environment of cleaners]. / Aerozole bakteryjne i grzybowe w srodowisku pracy firm sprzatajacych.

BACKGROUND: Cleaning services are carried out in almost all sectors and branches of industry. Due to the above, cleaners are exposed to various harmful biological agents, depending on the tasks performed and the commercial sector involved. The aim of this study was to assess the exposure of cleaning workers to biological agents based on quantitative and qualitative characteristics of airborne microflora. MATERIAL AND METHODS: A six-stage Andersen sampler was used to collect bioaerosols during the cleaning activities in different workplaces, including schools, offices, car services, healthy services and shops. Standard Petri dishes filled with blood trypticase soy agar and malt extract agar were used for bacterial and fungal sampling, respectively. RESULTS: The bioaerosol concentration values obtained during testing of selected workposts of cleaners were lower than the Polish recommended threshold limit values for microorganisms concentrations in public service. The most prevalent bacterial species in studied places were Gram-positive cocci (mainly of genera Micrococcus, Staphylococcus) and endospore-forming Gram-positive rods (mainly of genera Bacillus). Among the most common fungal species were those from genera Penicillium and Aspergillus. The size distribution analysis revealed that bioaerosols present in the air of workposts at shops, schools and car services may be responsible for nose and eye mucosa irritation and allergic reactions in the form of asthma or allergic inflammation in the cleaning workers. CONCLUSIONS: The study shows that occupational activities of cleaning workers are associated with exposure to airborne biological agents classified into risk groups, 1. and 2., according to their level of infection risk, posing respiratory hazard.

[Fibers as carriers of microbial particles]. / Wlókna jako nosniki czastek mikrobiologicznych.

BACKGROUND: The aim of the study was to assess the ability of natural, synthetic and semi-synthetic fibers to transport microbial particles. MATERIAL AND METHODS: The simultaneously settled dust and aerosol sampling was carried out in 3 industrial facilities processing natural (cotton, silk, flax, hemp), synthetic (polyamide, polyester, polyacrylonitrile, polypropylene) and semi-synthetic (viscose) fibrous materials; 2 stables where horses and sheep were bred; 4 homes where dogs or cats were kept and 1 zoo lion pavilion. All samples were laboratory analyzed for their microbiological purity. The isolated strains were qualitatively identified. To identify the structure and arrangement of fibers that may support transport of microbial particles, a scanning electron microscopy analysis was performed. RESULTS: Both settled and airborne fibers transported analogous microorganisms. All synthetic, semi-synthetic and silk fibers, present as separated threads with smooth surface, were free from microbial contamination. Natural fibers with loose packing and rough surface (e.g., wool, horse hair), sheaf packing and septated surface (e.g., flax, hemp) or present as twisted ribbons with corrugated surface (cotton) were able to carry up to 9×10(5) cfu/g aerobic bacteria, 3.4×10(4) cfu/g anaerobic bacteria and 6.3×10(4) cfu/g of fungi, including pathogenic strains classified by Directive 2000/54/EC in hazard group 2. CONCLUSIONS: As plant and animal fibers are contaminated with a significant number of microorganisms, including pathogens, all of them should be mechanically eliminated from the environment. In factories, if the manufacturing process allows, they should be replaced by synthetic or semi-synthetic fibers. To avoid unwanted exposure to harmful microbial agents on fibers, the containment measures that efficiently limit their presence and dissemination in both occupational and non-occupational environments should be introduced.

TiO2 Nanoparticles with Adjustable Phase Composition Prepared by an Inverse Microemulsion Method: Physicochemical Characterization and Photocatalytic Properties.

Titania nanoparticles (NPs) find wide application in photocatalysis, photovoltaics, gas sensing, lithium batteries, etc. One of the most important synthetic challenges is maintaining control over the polymorph composition of the prepared nanomaterial. In the present work, TiO2 NPs corresponding to anatase, rutile, or an anatase/rutile/brookite mixture were obtained at 80 °C by an inverse microemulsion method in a ternary system of water/cetyltrimethylammonium bromide/1-hexanol in a weight ratio of 17:28:55. The only synthesis variables were the preparation of the aqueous component and the nature of the Ti precursor (Ti(IV) ethoxide, isopropoxide, butoxide, or chloride). The materials were characterized with X-ray diffraction, scanning/transmission electron microscopy, N2 adsorption-desorption isotherms, FTIR and Raman vibrational spectroscopies, and diffuse reflectance spectroscopy. The synthesis products differed significantly not only in phase composition, but also in crystallinity, textural properties, and adsorption properties towards water. All TiO2 NPs were active in the photocatalytic decomposition of rhodamine B, a model dye pollutant of wastewater streams. The mixed-phase anatase/rutile/brookite nanopowders obtained from alkoxy precursors showed the best photocatalytic performance, comparable to or better than the P25 reference. The exceptionally high photoactivity was attributed to the advantageous electronic effects known to accompany multiphase titania composition, namely high specific surface area and strong surface hydration. Among the single-phase materials, anatase samples showed better photoactivity than rutile ones, and this effect was associated, primarily, with the much higher specific surface area of anatase photocatalysts.

Effectiveness of UV-C radiation in inactivation of microorganisms on materials with different surface structures.

INTRODUCTION AND OBJECTIVE: Ultraviolet light in the UV-C band is known as germicidal radiation and was widely used for both sterilization of the equipment and creation of a sterile environment. The aim of the study is to assess the effectiveness of inactivation of microorganisms deposited on surfaces with various textures by UV-C radiation disinfection devices. MATERIAL AND METHODS: Five microorganisms (3 bacteria, virus, and fungus) deposited on metal, plastic, and glass surfaces with smooth and rough textures were irradiated with UV-C light emitted by low-pressure mercury lamp and ultraviolet emitting diodes (LEDs), from a distance of 0.5 m, 1 m, and 1.5 m to check their survivability after 20-minute exposure. RESULTS AND CONCLUSIONS: Both tested UV-C sources were effective in inactivation of microorganisms; however, LED emitter was more efficient in this respect than the mercury lamp. The survival rate of microorganisms depended on the UV-C dose, conditioned by the distance from UV-C source being the highest at 0.5 m and the lowest at 1.5 m. For the tested microorganisms, the highest survival rate after UV-C irradiation was usually visible on glass and plastic surfaces. This observation should be considered in all environments where the type of material (from which the elements of technical equipment are manufactured and may be contaminated by specific activities) is important for maintaining the proper level of hygiene and avoiding the unwanted and uncontrolled spread of microbiological pollution.

Exposure of ventilation system cleaning workers to harmful microbiological agents.

BACKGROUND: Regular inspection of the cleanliness of the ventilation systems, as well as their periodic cleaning and disinfection, if necessary, are the main factors of the proper maintenance of each system. Performing maintenance operations on the ventilation system, workers are exposed to risk associated with the exposure to harmful biological agents. The aim of this study was to assess the employees' exposure to bioaerosols during maintenance work on ventilation systems. MATERIAL AND METHODS: Bioaerosol measurements were carried out using a button sampler. The microbial particles were collected on gelatin filters. Settled-dust samples from the inner surface of the air ducts and filter-mat samples were selected for the microbiological analysis. In the collected air, dust and filter samples the concentration of bacteria and fungi were determined. RESULTS: Bacteria and fungi concentrations ranged between 3.6 x 10(2)-2.2 x 10(4) CFU/m3 and 4.7 x 10(2)-4.5 x 10(3) CFU/m3 at workplaces where the operations connected with mechanical ventilation cleaning were performed and 2.2 x 10(4)-1.2 x 10(5) CFU/m2 and 9.8 x 10(1)-2.5 x 10(2) CFU/m3 at workplaces where filter exchange was performed, respectively. The qualitative analysis of microorganisms isolated from the air in all studied workplaces revealed that the most prevalent bacteria belonged to Bacillus genus. The average concentrations of bacteria and fungi in filter-mat samples were 3.3 x 10(3) CFU/cm2 and 1.4 x 10(4) CFU/cm2, respectively. In settled-dust samples, average concentrations were 591 CFU/100 cm2 and 52 CFU/100 cm2, for bacteria and fungi respectively. CONCLUSIONS: Workers cleaning ventilation systems are exposed to harmful biological agents classified into risk groups, 1 and 2, according to their level of the risk of infection. The research conducted in the workplace can be the basis of risk assessment related to exposure to harmful biological agents during maintenance work in ventilation.

Composites of Montmorillonite and Titania Nanoparticles Prepared by Inverse Microemulsion Method: Physico-Chemical Characterization.

TiO2/montmorillonite composites were synthesized using inverse micellar route for the preparation of titania nanoparticles (4-6 nm diameter) in 1-hexanol and for the dispersion of one of the clay components. Two series of composites were obtained: one derived from cetyltrimethylammonium organomontmorillonite (CTA-Mt), exfoliated in 1-hexanol, and the other from sodium form of montmorillonite (Na-Mt) dispersed by formation of an inverse microemulsion in 1-hexanol. The TiO2 content ranged from 16 to 64 wt.%. The composites were characterized with X-ray diffraction, scanning/transmission electron microscopy/energy dispersive X-ray spectroscopy, thermal analysis, and N2 adsorption-desorption isotherms. The Na-Mt-derived component was shown to undergo transformation to CTA-Mt, as indicated by basal spacing of 17.5 nm, due to the interaction with the CTABr surfactant in inverse microemulsion. It was also better dispersed and intermixed with TiO2 nanoparticles. As a result, the TiO2/Na-Mt series displayed superior textural properties, with specific surface area up to 256 m2g-1 and pore volume up to 0.247 cm3g-1 compared with 208 m2g-1 and 0.231 cm3g-1, respectively, for the TiO2/CTA-Mt counterpart. Members of both series were uniformly mesoporous, with the dominant pore size around 5 nm, i.e., comparable with the dimensions of titania nanoparticles. The advantage of the adopted synthesis method is discussed in the context of other preparative procedures used for manufacturing of titania-clay composites.

Poultry house as point source of intense bioaerosol emission.

INTRODUCTION AND OBJECTIVE: Intensive poultry farming is usually associated with massive exposure to organic dust, which is largely composed of microbiological origin particulates. The aim of the study is to assess occupational and environmental exposures to airborne bacteria, fungi, and Marek's disease virus emitted by a poultry house. MATERIAL AND METHODS: The concentrations of airborne microorganisms in a poultry house and its vicinity (250-500 m) at 3 different stages of the production cycle (i.e. empty poultry house, with 7-day-old and 42-day-old chickens) were stationary measured using Andersen and MAS impactors, as well as Coriolis and BioSampler impingers. The collected microbiota was taxonomically identified using molecular and biochemical techniques to characterize occupational exposure and its spatial dissemination. RESULTS: Although Marek's disease virus was not present in the tested air samples, the appearance of reared chickens in the poultry house resulted in an increase in airborne bacterial and fungal concentrations up to levels of 1.26 × 108 CFU/m3 and 3.77 × 104 CFU/m3, respectively. These pollutants spread around through the ventilation system, but their concentrations significantly decreased at a distance of 500 m from the chicken coop. A part of the identified microbiota was pathogens that were successfully isolated from the air by all 4 tested samplers. CONCLUSIONS: The poultry house employees were exposed to high concentrations of airborne microorganisms, including pathogens that may lead to adverse health outcomes. To protect them, highly efficient hygienic and technical measures regarding the poultry house interior and its ventilation, respectively, should be introduced to prevent both unwanted pollution and subsequent emission of microbial contaminants during intensive chicken breeding.

Production of pro-inflammatory mediators stimulated by exposure of poultry house workers to airborne dust particulates.

INTRODUCTION AND OBJECTIVE: Poultry house employees spend a significant part of their work shift being exposed to airborne particulate pollutants. The aim of this study was to assess their exposure at different stages of chicken production cycle, based on quantification of pro-inflammatory mediators (IL-1ß, IL-6, IL-8, and TNFα) in nasal lavage (NAL) samples. MATERIAL AND METHODS: The concentrations of airborne dust at 3 different stages of the production cycle (i.e. empty poultry house, with 7- and 42-day-old chickens) were stationary measured using Grimm spectrometer, as well as CIS and Button samplers. The dust collected by the latter 2 samplers was analyzed for endotoxin and (1→3)-ß-D-glucan content. NAL samples were collected from employees after their work shift to determine the pro-inflammatory mediator levels. RESULTS: The maximum particulate aerosol, endotoxin, and (1→3)-ß-D-glucan concentrations at workplaces reached the levels of 4.12 mg/m3, 45.21 ng/m3, and 56.54 ng/m3, respectively. The IL-1ß, IL-6, and IL-8 concentrations in NAL samples ranged between 0.62-18.12 pg/mL, <0.70-25.37 pg/mL, and <3.50-259.5 pg/mL, respectively. All TNFα levels were below 4 pg/mL. There were no significant differences between these cytokine concentrations in NAL samples collected at different stages of chicken breeding in either 'winter' or 'summer' seasons. CONCLUSIONS: Inhalation stimulation with poultry dust containing endotoxins and (1→3)-ß-D-glucans resulted in the production of pro-inflammatory mediators, which proves the course of immunological processes in the exposed employees that may lead to adverse effects. The use of nasal lavage fluid in the control of such exposure confirms that NAL analysis is a reliable laboratory tool for assessing the impact of poultry dust on exposed farm workers.

Intensive poultry farming: A review of the impact on the environment and human health.

Poultry farming is one of the most efficient animal husbandry methods and it provides nutritional security to a significant number of the world population. Using modern intensive farming techniques, global production has reached 133.4 mil. t in 2020, with a steady growth each year. Such intensive growth methods however lead to a significant environmental footprint. Waste materials such as poultry litter and manure can pose a serious threat to environmental and human health, and need to be managed properly. Poultry production and waste by-products are linked to NH3, N2O and CH4 emissions, and have an impact on global greenhouse gas emissions, as well as animal and human health. Litter and manure can contain pesticide residues, microorganisms, pathogens, pharmaceuticals (antibiotics), hormones, metals, macronutrients (at improper ratios) and other pollutants which can lead to air, soil and water contamination as well as formation of antimicrobial/multidrug resistant strains of pathogens. Dust emitted from intensive poultry production operations contains feather and skin fragments, faeces, feed particles, microorganisms and other pollutants, which can adversely impact poultry health as well as the health of farm workers and nearby inhabitants. Fastidious odours are another problem that can have an adverse impact on health and quality of life of workers and surrounding population. This study discusses the current knowledge on the impact of intensive poultry farming on environmental and human health, as well as taking a look at solutions for a sustainable future.

[Exposure of ventilation system cleaning workers to harmful biological and chemical agents]. / Narazenie pracowników konserwujacych instalacje wentylacyjne na szkodliwe czynniki biologiczne i chemiczne.

Regular checking on the cleanliness of the ventilation systems, as well as their periodic cleaning and, if necessary, disinfection are for the proper maintenance of each system. During maintenance operations (repairs, cleaning, filter replacement), workers are at risks associated with exposure to hazardous chemicals and harmful biological agents. In ventilation systems there are usually favorable conditions for the development of microorganisms, mainly bacteria and fungi, due to surfaces contaminated with dust particles or increased humidity caused by ventilation ducts, air filters, thermal insulation, noise dampers, air coolers, etc. Workers who perform cleaning and disinfection operations on ventilation systems are exposed to chemical agents through contacts with contaminants released from sealing materials, adhesives, fireproof lining and insulating materials, volatile organic compounds present in air filters, noise dampers and insulating materials, as well as with cleaning agents and disinfectants. Exposure to harmful chemical and biological agents may induce adverse health effects ranging from allergic reactions and irritation through infections to toxic reactions and other non-specific symptoms. Due to lack of studies on the exposure of this group of workers, employers face great difficulties in identifying hazards, which prevent them from performing an occupational risk assessment.

Exposure to harmful microbiological agents during the handling of biomass for power production purposes.

BACKGROUND: Despite numerous benefits related to the utilization of biomass as an alternative source of energy, the handling of biomass creates a risk for the power industry workers of exposure to harmful microbiological agents. The purpose of this study was to evaluate the exposure of the workers to such agents at a power plant co-firing biomass with coal. This assessment was based on quantitative and qualitative characteristics of bioaerosols, supplemented with the analysis of biomass samples. MATERIAL AND METHODS: Air samples were collected with both MAS and Andersen six-stage impactors. Two different kinds of biomass samples used in the co-firing technological process were collected: sunflower seed peel pellet and wood chips. Bacterial and fungal concentrations were assessed in the air and biomass samples, and isolated microbial colonies were identified to the genus and/or species level. RESULTS: Bacterial and fungal concentrations at workplaces ranged between 5.1 x 10(2) cfu/m3 and 2.0 x 10(4) cfu/m3, and between 2.2 x 10(2) cfu/m3 and 2.3 x 10(4) cfu/m3, respectively. The highest concentrations were determined at workplaces related to reloading, screening and biomass transport via conveyor belts to silos. Fungi representing the genus Aspergillus, including A. fumigatus, A. niger, A. flavus and Gram-negative rods of the genus Citrobacter, Pseudomonas and Rahnella prevailed in the air at all investigated workplaces. Bacterial and fungal concentrations in biomass samples amounted to 1.8 x 10(6) cfu/g and 1.1 x10(6) cfu/g, respectively. The qualitative analysis revealed that the composition of species in the biomass samples was similar to that observed in the air at workplaces. CONCLUSIONS: Workers engaged in the biomass combustion technology are exposed to bioaerosol containing potentially pathogenic bacteria and fungi.

Comparative Physicochemical and Catalytic Study of Nanocrystalline Mg-Al Hydrotalcites Precipitated with Inorganic and Organic Bases.

Synthetic Mg-Al hydrotalcites (HT) are environmentally friendly solid bases frequently applied as catalysts in base catalyzed reactions. The most common synthesis method, using NaOH as precipitant, is problematized by the possibility of introducing undesired Na contamination. Alkali-free synthesis is usually performed with NH3aq, a precipitant which is less efficient in incorporation of Mg into HT lattice. In the present work, organic bases, tetrabutylammonium hydroxide and choline hydroxide, were successfully employed as precipitating agents in a new alkali-free route of Mg-Al HT synthesis. HT solids were also obtained with inorganic bases, NH3aq and NaOH. Characterization with X-ray diffraction, elemental analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy and thermogravimetry/differential scanning calorimetry, confirmed the formation of nanocrystalline HT compounds with all employed bases. HT prepared with NH3aq exhibited an Mg deficit, which was detrimental to the catalytic activity in base catalyzed reactions. The effect was attributed to the tendency of Mg2+ to form ammine complexes, a conclusion supported by quantum mechanical calculations. HT prepared with NaOH showed the highest crystallinity, which was unfavorable for catalytic application. The addition of starch to the synthesis medium provided a means by which to diminish the crystal size of all HT precipitates. Catalytic tests of the Baeyer-Villiger oxidation of cyclohexanone demonstrated that the highest yields of ε-caprolactone were obtained with fine-crystalline HT catalysts prepared with organic bases in the presence of a starch template.

Across-Shift Changes in Viable Nasal Bacteria among Waste-Incineration Plant Workers-A Pilot Study.

The aim of this pilot study was to assess the time-related changes in viable nasal bacteria concentrations among waste-incineration plant (WIP) workers compared to a group of office building (OB) workers outside the plant. In total, 20 volunteers participated in the study, including 14 WIP and 6 OB workers. WIP workers were divided into two sub-groups: supervisory staff (SVS) and maintenance and repair workers (MRW). Nasal swabs were collected before and after the morning work shift. Airborne bacteria were sampled with a six-stage impactor to assess the bioaerosol size distribution. The analysis showed that a significant, almost three-fold increase in nasal bacterial concentration was found only among WIP workers, and this referred mainly to anaerobic species. The load of anaerobic bacteria at the beginning of work was 12,988 CFU/mL, and after work shift 36,979 CFU/mL (p < 0.01). Significant increases in microbial concentrations was found only in the MRW subgroup, among non-smoking workers only. The results showed increased bacterial concentration in WIP nasal samples for as many as 12 bacterial species, including, e.g., Streptococcus constellatus, Peptostreptococcus spp., E. coli, and P. mirabilis. These preliminary data confirmed that the nasal swab method was helpful for assessment of the workers' real-time exposure to airborne bacteria.

Retinal Microvascular Changes in COVID-19 Bilateral Pneumonia Based on Optical Coherence Tomography Angiography.

The purpose of this study was to evaluate retinal and choroidal microvascular alterations with optical coherence tomography angiography (OCTA) in COVID-19 patients hospitalized because of bilateral pneumonia caused by SARS-CoV-2. The vessel density (VD) and foveal avascular zone (FAZ) of 63 patients with SARS-CoV-2 pneumonia who had positive polymerase chain reaction (PCR) tests and who recovered after receiving treatment and 45 healthy age- and gender-matched controls were evaluated and compared using OCTA in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). The VD was also estimated in both groups in the choriocapillaris (CC). In COVID-19 patients, there was a statistically significant difference between the patients and a control group in both superficial (FAZs) and deep (FAZd) avascular zone (p = 0.000). The VD was significantly lower in the foveal area in choriocapillaris (p = 0.046). There were no statistically significant changes in the VD in the superior, inferior, nasal, and temporal quadrants in superficial and deep plexus, or in the choriocapillaris. The VD was not significantly lower in the foveal area in superficial or deep plexus. COVID-19 may affect the retinal vasculature, causing ischemia, enlargement of the FAZ, and lowering of the VD in the choriocapillaris area. Routine ophthalmic examination after SARS-CoV-2 infection should be considered in the course of post-infectious rehabilitation.

Occupational exposure to anaerobic bacteria in a waste sorting plant.

The study focused on exposure assessment to bacterial aerosols and organic dust in waste sorting plant. Samples were collected at different workplaces of waste sorting cycle i.e.: waste press, reloading area, loading of conveyor belt, sorting cabin, sorting hall, and control room. A quantitative analysis of aerobic and anaerobic bacteria was supplemented by qualitative analysis of anaerobic biota with the use of culture-based methods and biochemical tests. In addition, inhalable dust concentrations were also evaluated. To confirm the presence of Clostridium genus, the PCR reaction with specific primers (Chis150f and ClostIr) was performed. The average concentration of total bacteria in waste sorting plant was 4347 CFU m-3 (SD = 2439), of which 66% were anaerobic strains (2852 CFU m-3; SD = 2127). It was found that about 24% of anaerobic bacteria belonged to Clostridium genus (682 CFU m-3; SD = 633). The highest contamination with anaerobic bacteria was observed near the waste reloading plant (3740 CFU m-3), and the lowest in the control room (850 CFU m-3). The average concentration of inhalable dust in the waste sorting plant was 0.81 mg m-3 (SD = 0.59). The correlation analysis showed that the presence of anaerobic bacteria, including clostridia was significantly determined by the microclimate parameters. Qualitative analysis showed the presence of 16 anaerobic species belonging to 9 genera, of which Actinomyces, Clostridium, and Gemella were present at all workplaces. The molecular analysis confirmed the presence of Clostridium genus in both bioaerosol and settled dust samples.Implications: The study showed that anaerobic bacteria should be taken into account as an important component of this microbiota when assessing the exposure of waste sorting workers to biological agents. However, future studies should investigate more precisely how the composition of sorted waste as well as the season can affect the diversity of anaerobic bacteria in this working environment. More attention should be paid to regular cleaning of equipment surfaces in the plant, as deposited organic dust is an important reservoir of anaerobic bacteria, including those of a potentially pathogenic nature.

Microbial contamination of money sorting facilities.

INTRODUCTION: Money is the most common item with which we have daily contact. Circulated banknotes and coins can become microbiologically contaminated and act as both a source and a means of spreading such pollutants. MATERIAL AND METHODS: The study was carried out in three money sorting facilities in Poland. Bioaerosol samples were collected using a 6-stage Andersen impactor, and microorganisms deposited on tabletop surfaces were sampled using the swab method. Bacterial and fungal concentrations were calculated and all isolated species were taxonomically identified. RESULTS: The study confirmed that means of payment are active sources of microbial emission in money sorting facilities. The bioaerosol concentrations did not exceed the threshold limit values proposed for this type of office premises. It confirms that ventilation systems in these facilities worked efficiently, protecting them from the migration of microbial contaminants present in both indoor and outdoor (atmospheric) background air. On the other hand, the average concentrations of bacteria and fungi on tabletop surfaces in banknote and coin sorting rooms were above the proposed purity levels for indoor surfaces and should be treated as microbiologically contaminated. Microbiota isolated from the air and surfaces were very diverse and among those strains were bacterial and fungal pathogens that can pose a health threat to exposed individuals. CONCLUSIONS: The results showed that employees in money sorting facilities were exposed to microorganisms that may contribute to the development of adverse health outcomes. To protect them, highly efficient hygienic measures should be introduced in this working environment, to prevent both unwanted pollution and subsequent secondary emission of microbial contaminants from sorted means of payment and tabletop surfaces.