Breaking the cycle of excessive conservatism: Evaluating the γ-radiation dose from building materials.

Radionuclide content in building materials is regulated in most European countries by calculating the activity concentration index. The I-index does not account for the properties nor the application of the material but provides a conservative evaluation of the annual γ-radiation dose. Using a Monte Carlo toolkit, EGSnrc, this study calculated doses from building materials in less conservative set-ups by focusing on materials with a potential for recycling NORM residues, such as Portland cement, ceramics, gypsum, and mineral insulation. It was observed that proper consideration of building material geometry strongly affected the indoor dose rate. Regulating low-density materials and finishing materials such as gypsum and insulation under the same framework as high-density and high-bulk materials proved problematic because the doses differ by orders of magnitude. The current reference values for radionuclide concentrations used in calculating the I-index do not apply to most construction materials. For many types of building materials, higher radionuclide concentrations in the material could be allowed without contradicting the annual effective dose reference for the public. This illustrates the potential for boosting the use of NORM residues in various construction applications.

Assessment of 222Rn, 226Ra, 238U, 218Po, and 214Po activity concentrations in the blood samples of workers at selected building material factories in Erbil City.

The objective of this research is to assess the impact of radon concentration on workers at certain construction material industries in Erbil, Kurdistan Region of Iraq. The CR-39 solid-state track detector was used in this experiment to monitor radon levels and their daughters. For this purpose, as a case study group, 70 workers were divided into seven subgroups (gypsum, cement plant, lightweight block, marble, red brick 1, crusher stone, and concrete block 2), and 20 healthy volunteers were selected as a control group. The findings demonstrate that the mean concentrations of radon, radium, uranium, and radon daughters deposited on the detector face (POS) and chamber walls (POW) for the case study group were 9.61 ± 1.52 Bq/m3, 0.33 ± 0.05 Bq/Kg, 5.39 ± 0.86 mBq/Kg, 4 ± 0.63, and 16.62 ± 2.64 mBq/m3, whereas for the control group, they were 3.39 ± 0.58 Bq/m3, 0.117 ± 0.03 Bq/Kg, 1.91 ± 0.32 mBq/Kg, 1.41 ± 0.24, and 5.88 ± 1 mBq/m3, respectively. The statistical analysis revealed that radon, radium, uranium, and POW and POS concentrations were statistically significant (p ≤ 0.001) in the samples for the case study groups of cement, lightweight block, red brick 1, marble, and crusher stone factories in comparison to the control group; however, the results for gypsum and concrete block 2 factories were not statistically significant in comparison to the control group. Intriguingly, the radon levels in every blood sample examined were far lower than the 200 Bq/m3 limit established by the International Atomic Energy Agency. Hence, it may be argued that the blood is devoid of contaminants. These results are crucial for determining whether or not an individual is exposed to substantial quantities of radiation and for demonstrating a link between radon, its daughter, uranium, and the prevalence of cancer among workers in the Kurdish region of Iraq.

The anatomical and micromorphological properties of endemic species to gypsic soils of Semnan, Iran.

The gypsum habitats of Iran are significant reserves of biodiversity containing endemic and rare species. Despite the limited understanding of its characteristics and habitat, it has become essential to study the endemic species of the Semnan gypsic soil. Fresh samples of studied species including Acantholimon cymosum, Astragalus fridae, Astragalus semnanensis, Euphorbia gypsicola, Gypsophila mucronofolia, Moltkia gypsaceae and Nepeta eremokosmus were collected in the wild during the growth season. Leaf surface and leaf cross-sections were considered. The longest hair length was related to A. fridae, A. semnanensis and M. gypsaceae species. The shorter hairs belong to the species A. cymosum, G. mucronofolia and E. gypsicola. Crystals called cystolites were seen in the epidermal cell wall of A. semnanensis leaves. The anatomical characteristics of these species' leaves indicate the presence of dry structures. Using micromorphological studies, we analyzed the hairs of the studied species in terms of their shapes, sizes, and densities. We found some species have hairs with special appendages, which is due to the special conditions in which they have grown. Xeromorphic stomata were found on both leaf surfaces of all endemic gypsophyte plants of Semnan. Several studies have shown that gypsophytes have a specialized mechanism for regulating the absorption of sulfur and calcium from soils containing calcium sulfate or gypsum by their roots. The current study provides novel insights into the response of plant species to extreme conditions and potential adaptation strategies at micromorphological levels.

Outdoor Atmospheric Micro-/Nanomineral-Mediated Organochlorine Pesticides in Sichuan Basin, China: Adsorption, Occurrence, and Risk Assessment.

Atmospheric micro-/nanominerals play an important role in the adsorption, enrichment, and migration of organochlorine pesticides (OCPs). In the present study, the correlations between OCPs and minerals in outdoor atmospheric dustfall were investigated, and the correlations were used to speculate the source of p,p'-(dicofol+dichlorobenzophenone [DBP]), which is the sum of p,p'-dicofol and p,p'-DBP. Atmospheric dustfall samples were collected from 53 sites in the Chengdu-Deyang-Mianyang economic region in the Sichuan basin. In this region, 24 OCPs were analyzed by gas chromatography-tandem mass spectrometry. The average concentration of 24 OCPs was 51.2 ± 27.4 ng/g. The results showed that the concentration of Σ24 OCPs in urban areas was higher than that in suburban areas (p < 0.05). Minerals in atmospheric dustfall were semiquantitatively analyzed by X-ray diffraction. The primary minerals were quartz, calcite, and gypsum. A Spearman correlation analysis of OCPs and minerals showed that low-volatility OCPs could be adsorbed by minerals in atmospheric dustfall. A density functional theory simulation verified that p,p'-(dicofol+DBP) in atmospheric dustfall was primarily derived from the p,p'-dicofol adsorbed by gypsum. Isomeric ratio results suggested that the samples had weathered lindane and chlordane profiles and confirmed that residents in the Sichuan basin used technical dichlorodiphenyltrichloroethane. Finally, the OCPs were evaluated to determine the potential risk of cancer in adults and children from OCP exposure. Exposure to OCPs via atmospheric dustfall was safe for adults. The cancer risk for children exposed to OCPs was slightly lower than the threshold value (10-6 ) under a high dust ingestion rate, which poses a concern. Environ Toxicol Chem 2023;42:594-604. © 2022 SETAC.

Natural radioactivity and radiological risk assessment due to building materials commonly used in Erbil city, Kurdistan region, Iraq.

Radiometric monitoring of construction materials is required for estimating the interior and exterior exposure to ionizing radiation emitted by terrestrial radioactive elements in building materials. Using gamma-ray spectroscopy, the activity concentrations of 226Ra, 232Th, and 40 K in fifty-two samples from eighteen different building materials commonly used in Erbil city, Kurdistan region, Iraq, were evaluated to assess possible radioactive dangers to human health. The activity concentrations of 226Ra, 232Th and 40 K ranged from 1 ± 0.1 (gypsum board) to 130 ± 11 (granite), 1.3 ± 0.2 (gypsum) to 66 ± 8 (ceramic sample), and 18.74 ± 4 (gypsum) to 1061.708 ± 40 (granite) with an average of 28 ± 5, 20.7 ± 4, and 340.8 ± 18 (average ± standard deviation), respectively. Radiological indicators (activity concentration index, alpha and gamma index, hazard indices, interior absorbed gamma dose rate and the corresponding yearly effective dosage rate, and excess lifetime cancer risk) were computed to assess the health risks associated with these building materials. Consideration was given to the indoor annual effective dosage for common construction materials, the radon surface expiration rate, and the indoor radon concentration. The mean values of activity concentration were then inputted into the RESRAD-BUILD computer software to calculate a resident's long-term radiation exposure. The dosages were measured over a range of 0 to 70 years. From 0 to 30 years, there was a significant change in dosages; however, from 30 to 70 years, the dosages were reasonably consistent. This research demonstrates that granite samples are not safe for dwellings with poor ventilation (especially those without windows). In general, other investigated construction materials in the buildings are deemed safe for the population, since the computed values for these parameters fall within the well-being restrictions or criterion values.

Speciation, bioaccessibility and human health risk assessment of chromium in solid wastes from an ultra-low emission coal-fired power plant, China.

Chromium (Cr) in solid wastes from ultra-low emission (ULE) coal-fired power plants (CFPPs) could engender adverse effects on environment and human health. Hence, solid waste samples containing bottom ash, fly ash, gypsum and sludge were collected from a typical ULE CFPP in China to study the distribution, speciation, bioaccessibility and human health risk of Cr. The results showed that Cr was depleted in gypsum, whereas significantly enriched in bottom ash, fly ash and sludge comparing with feed coal. The ratios of Cr(VI) to total Cr in solid wastes were relatively low, but the increase of flow fractions in Cr chemical binding forms implied the deterioration of environmental stability. Based on the in vitro simulated digestion methods of solubility bioavailability research consortium (SBRC) and physiologically based extraction test (PBET), the bioaccessibility of Cr in the gastric and intestinal phases reached the highest values in either gypsum or sludge. After incorporating bioaccessibility in human health risk assessment, the carcinogenic risk (CR) within acceptable limits of Cr in solid wastes to adults and children was concluded, with the non-carcinogenic hazard quotient (HQ) was all within the safety threshold. The Monte Carlo model was applied to evaluate the uncertainty analysis of human health risk assessment at 5% and 95% confidence interval, and the fitting results were consistent with the calculation results of the carcinogenic and non-carcinogenic risk for adults and children. This study is expected to provide insights for the integration of bioaccessibility into the health risk assessment of Cr in solid wastes from ULE CFPPs, thus is conducive to the disposal of solid wastes and human health protection.

Hydrogeochemical assessment of carcinogenic and non-carcinogenic health risks of potentially toxic elements in aquifers of the Hindukush ranges, Pakistan: insights from groundwater pollution indexing, GIS-based, and multivariate statistical approaches.

Globally, potentially toxic elements (PTEs) and bacterial contamination pose health hazards, persistency, and genotoxicity in the groundwater aquifer. This study evaluates PTE concentration, carcinogenic and noncarcinogenic health hazards, groundwater quality indexing (GWQI-model), source provenance, and fate distribution in the groundwater of Hindukush ranges, Pakistan. The new estimates of USEPA equations record new research dimensions for carcinogenic and noncarcinogenic hazards. The principal component analysis (PCA), mineral phases, and spatial distribution determine groundwater contamination and its impacts. The average concentrations of PTEs, viz., Cd, Cu, Co, Fe, Pb, and Zn, were 0.06, 0.27, 0.07, 0.55, 0.05, and 0.19 mg/L, and E. coli, F. coli, and P. coli were 27.5, 24.0, and 19.0 CFU/100 ml. Moreover, the average values of basic minerals, viz., anhydrite, aragonite, calcite, dolomite, gypsum, halite, and hydroxyl apatite, were 0.4, 2.4, 2.6, 5.1, 0.6, and - 4.0, 11.2, and PTE minerals like monteponite, tenorite, cuprite, cuprous ferrite, cupric ferrite, ferrihydrite, goethite, hematite, lepidocrocite, maghemite, magnetite, massicot, minium, litharge, plattnerite, and zincite were - 5.5, 2.23, 4.65, 18.56, 20.0, 4.84, 7.54, 17.46, 6.66, 9.67, 22.72, - 3.36, 22.9, 3.16, - 18.0, and 1.46. The groundwater showed carcinogenic and non-carcinogenic health hazards for children and adults. The GWQI-model showed that 58.3% of samples revealed worse water quality. PCA revealed rock weathering, mineral dissolution, water-rock interaction, and industrial effluents as the dominant factors influencing groundwater chemistry. Carbonate weathering and ion exchange play vital roles in altering CaHCO3 type to NaHCO3 water. In this study, E. coli, F. coli, P. coli, EC, turbidity, TSS, PO43─, Na+, Mg+2, Ca+2, Cd, Co, Fe, and Pb have exceeded the World Health Organization (WHO) guidelines. The carcinogenic and non-carcinogenic impacts of PTEs and bacterial contamination declared that the groundwater is unfit for drinking and domestic purposes.

Natural radioactivity and radiation hazard assessment of industrial wastes from the coastal phosphate treatment plants of Gabes (Tunisia, Southern Mediterranean Sea).

This work is a first contribution to the knowledge of natural radionuclides (226Ra, 238U, 40K, and 232Th) activities in phosphate rock (NORM), phosphogypsum, and phosphogypsum foam (TENORM) from the coastal fertilizer plants of Gabes (Southeastern Tunisia) and the assessment of their radiation hazards on human health and the surrounding environment. In the three studied materials, activities were found to be in the range of 35.4 (40K)-375.1 (226Ra), 10.0 (40K)-220.2 (226Ra), and 79.2 (232Th)-1168.6 Bq kg-1 (226Ra), respectively. Considering the studied radionuclides and materials, the corresponding decreasing activity orders were found to be 226Ra > 238U > 40K > 232Th and PGF > PR > PG, respectively. All human health hazard indices exceeded the worldwide recommended safety limits, which show that the workers in Gabes phosphate fertilizer plants as well as the neighboring human community may potentially be exposed to significant radiation, which may cause several diseases and malformations. It is therefore recommended to avoid and/or reduce the potential fertilizer industry radioactive impact in the area.

The combined effects of nitrogen fertilizer, humic acid, and gypsum on yield-scaled greenhouse gas emissions from a coastal saline rice field.

In coastal saline rice fields, rice production shows high greenhouse gas (GHG) emissions but low nitrogen use efficiency (NUE). However, few studies have focused on the combined effects of nitrogen (N) fertilizer and soil ameliorants on GHG emissions. Thus, a field experiment was conducted to study the combined effects of N fertilizer, humic acid, and gypsum on the global warming potential (GWP), yield-scaled greenhouse gas intensity (GHGI), rice grain yield, and NUE in coastal saline rice fields in southeastern China. The experiment was conducted with eight treatments: N0, N1, N0H1, N1H1, N0G1, N1G1, N0H1G1, and N1H1G1. The codes N0, N1, H1, and G1 represented treatments without N (0 kg N ha-1), with N (300 kg N ha-1), with humic acid (0.6 t ha-1), and with gypsum (0.6 t ha-1), respectively. Compared with the treatments without N addition, the application of N fertilizer significantly increased N2O emissions and grain yield by 41.9~130.6% and 32.8~57.5%, respectively, while significantly decreased the yield-scaled GHGI by 9.4~31.9%. Humic acid amendment significantly increased N2O emissions and grain yield as compared with the treatments without humic acid. Gypsum addition had no significant effects on CH4 and N2O emissions, GWP, yield-scaled GHGI, and grain yield in relation to the treatments without gypsum. In addition, compared with the N1 treatment, the N1H1, N1G1, and N1H1G1 treatments increased the grain yield by 18.3% (p < 0.05), 2.3%, and 10.4%, and decreased yield-scaled GHGI by 9.6%, 20.5%, and 31.2% (p < 0.05), despite similar GWPs, respectively. Overall, the N1H1 and N1H1G1 treatments are the appropriate fertilizer management to realize high yield together with low environmental impacts in coastal saline rice fields in China.

Air pollution impact on architectural heritage of Morocco: Combination of synchronous fluorescence and ATR-FTIR spectroscopies for the analyses of black crusts deposits.

The work is focusing on air pollution impacts on historical limestone buildings located in urban areas in Morocco. Black crusts sampled on the façades of two ancient limestone monuments, dating back to the 12th and 20th centuries edified in the cities of Salé and Casablanca, have been analyzed by means of ATR-FTIR and synchronous fluorescence spectroscopies. Infrared analyses revealed degradation products, mainly gypsum due to calcite sulphation under wetness and SO2 rich oil fired soot, and oxalates due to ancient biological weathering. Synchronous fluorescence permitted the identification of the most hazardous PAHs along with other non-identified fluorescent organics; this technique appeared efficient and suitable for the analysis of fluorescent pollutants entrapped in black crusts. Such results keeping track of air pollution causing disfigurement of architectural heritage must alarm both cultural heritage and environmental decision makers.

A potential source for PM2.5: Analysis of fine particle generation mechanism in Wet Flue Gas Desulfurization System by modeling drying and breakage of slurry droplet.

Aerosol particulate matter with dynamic diameter smaller than 2.5 µm (PM2.5) is the main cause for haze pollution in China. As a dominant precursor of PM2.5, SO2 emitted from industrial process is now strictly controlled by using limestone/gypsum Wet Flue Gas Desulfurization (WFGD) system in China. However, a phenomenon that fine particle derived from WFGD is recently addressed, and is suggested to be a potential source of primary PM2.5. Herein, a first investigation into the particle generation mechanism in WFGD system is conducted with a novel droplet (containing particles) drying and breakage model. The proposed model considers a random and porous crust instead of the previous regular crust assumption, and is verified by comparing the modeling results with measurements. An orthogonal test with four factors and three levels is carried out through modeling calculation, and flue gas temperature (Tg) in the inlet is found to be a governing parameter for PM2.5 yields in WFGD. With Tg in range of 120-160 °C, PM2.5 yields in desulfurizing tower can reach a maximum value at ∼2 × 108 cm-3 under typical WFGD condition. To avoid this situation and reduce the PM2.5 generation, Tg is suggested to be lower than 120 °C. Additionally, a new insight of the elimination effect of gas-gas heater (GGH) on "gypsum rain" in WFGD system is provided.

Quantifying fat, oil, and grease deposit formation kinetics.

Fat, oil, and grease (FOG) deposits formed in sanitary sewers are calcium-based saponified solids that are responsible for a significant number of nationwide sanitary sewer overflows (SSOs) across United States. In the current study, the kinetics of lab-based saponified solids were determined to understand the kinetics of FOG deposit formation in sewers for two types of fat (Canola and Beef Tallow) and two types of calcium sources (calcium chloride and calcium sulfate) under three pH (7 ± 0.5, 10 ± 0.5, and ≈14) and two temperature conditions (22 ± 0.5 and 45 ± 0.5 °C). The results of this study displayed quick reactions of a fraction of fats with calcium ions to form calcium based saponified solids. Results further showed that increased palmitic fatty acid content in source fats, the magnitude of the pH, and temperature significantly affect the FOG deposit formation and saponification rates. The experimental data of the kinetics were compared with two empirical models: a) Cotte saponification model and b) Foubert crystallization model and a mass-action based mechanistic model that included alkali driven hydrolysis of triglycerides. Results showed that the mass action based mechanistic model was able to predict changes in the rate of formation of saponified solids under the different experimental conditions compared to both empirical models. The mass-action based saponification model also revealed that the hydrolysis of Beef Tallow was slower compared to liquid Canola fat resulting in smaller quantities of saponified solids. This mechanistic saponification model, with its ability to track the saponified solids chemical precursors, may provide an initial framework to predict the spatial formation of FOG deposits in municipal sewers using system wide sewer collection modeling software.

Measurement of slurry droplets in coal-fired flue gas after WFGD.

China owns the world's largest capacity of coal-fired power units. By the end of 2012, the capacity of installed national thermal power has been 819.68 million kilowatts. The latest standard requires that newly built power plants emit SO2 in no more than 100 mg/m(3) and the emission of old ones be lower than 200 mg/m(3) while in some key areas the emission should be controlled under 50 mg/m(3). So by the end of 2012, 90% of the active coal-fired units have been equipped with flue gas desulfurization devices. Among the desulfurization methods adopted, limestone-gypsum wet flue gas desulphurization accounts for 92%, causing the problem of fine droplets in the exhaust gas after defogger, which may even form "gypsum rain." At present, sampling methods are widely used at home and abroad, such as magnesium ion tracer method, modified magnesium ion tracer method and chemical analysis. In addition, some scholars use aerodynamic methods, such as ELPI, to measure the diameter distribution and concentration. The methods mentioned above all have their own demerits, such as the inability to on-line, continuous measurements and the need of prolonged measuring time. Thus, in this paper some potential optical on-line methods are presented, such as Fraunhofer diffraction pattern analysis and wavelength-multiplexed laser extinction. Also brought up are their measuring scope and merits. These methods have already been utilized to measure small liquid droplets and their demonstrations and evaluations are as well stated. Finally, a 3D imaging method based on digital holographic microscope is proposed for in-line measurement of size and concentration of slurry droplets. The feasibility of this method is demonstrated by preliminary experimental investigation.

Temporary cementation in total ankle arthroplasty.

Total ankle arthroplasty can be technically demanding in patients with poor bone quality. In bone fragile patients, the use of a temporary cementation technique ("biocementation") can assist in providing a stable, secure implant interface with native bone that is of poor quality. I report the short-term results of 9 ankles (7 consecutive patients) undergoing total ankle replacement with temporary cementation using a slowly resorbable injectable bone graft substitute composed of 75% calcium sulfate and 25% calcium phosphate.

Commonly used metal and crystalline salts in South African traditional medicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional medicines in the form of plants, animals and/or minerals are used by millions of South Africans. There is currently no data regarding the commonly used mineral elements thus the potential benefits or hazards of such products remain unclear. MATERIALS AND METHODS: Metal and crystalline salts were purchased from a rural market (Nongoma, Zululand, South Africa). Information regarding the colloquial name, price and weight was recorded. Energy dispersive X-ray spectroscopy (EDX) was used to quantatively determine the unknown salts. RESULTS: Six widely available salts were analyzed. Ndonya, as it is colloquially known, refers to two products which look identical to the untrained eye-one is dyed table salt and the other is hexavalent chromium. A further product used medicinally, although not widely available, was identified as iron chromite ore. CONCLUSIONS: The array of substances documented, ranging from benign to carcinogenic, stresses the importance of documenting components used in traditional medicine and confirms the necessity to regulate South Africa traditional medicine. Healthcare workers should be aware of the complexities of using such metal salt.

Phytoremediation potential of Arabidopsis thaliana, expressing ectopically a vacuolar proton pump, for the industrial waste phosphogypsum.

Phosphogypsum (PG) is a by-product of the phosphorus-fertiliser industry and represents an environmental concern since it contains pollutants such as cadmium (Cd). We have recently shown that the overexpression of a proton pump gene (TaVP1) in transgenic tobacco (Nicotiana tabacum) led to an enhanced Cd tolerance and accumulation. The aim of this study was to evaluate the potential of transgenic Arabidopsis thaliana plants harbouring the TaVP1 gene to phytoremediate phosphogypsum. A pot experiment was carried out under greenhouse conditions. Transgenic A. thaliana plants harbouring the TaVP1 gene were grown on various substrates containing phosphogypsum (0, 25, 50 and 100 %) for 40 days. At the end of the growth period, we examined the growth (germination, root length, fresh weight) and physiological parameters (chlorophyll and protein contents, catalase activity and proteolysis) as well as the cadmium, Mg, Ca, and P contents of the A. thaliana plants. In order to evaluate Cd tolerance of the A. thaliana lines harbouring the TaVP1 gene, an in vitro experiment was also carried out. One week-old seedlings were transferred to Murashige and Skoog agar plates containing various concentrations of cadmium; the germination, total leaf area and root length were determined. The growth and physiological parameters of all A. thaliana plants were significantly altered by PG. The germination capacity, root growth and biomass production of wild-type (WT) plants were more severely inhibited by PG compared with the TaVP1 transgenic A. thaliana lines. In addition, TaVP1 transgenic A. thaliana plants maintained a higher antioxidant capacity than the WT. Interestingly, elemental analysis of leaf material derived from plants grown on PG revealed that the transgenic A. thaliana line accumulated up to ten times more Cd than WT. Despite its higher Cd content, the transgenic A. thaliana line performed better than the WT counterpart. In vitro evaluation of Cd tolerance showed that TaVP1 transgenic A. thaliana lines were more Cd-tolerant than the WT plants. These results suggested that ectopic expression of a vacuolar proton pump in A. thaliana plants can lead to various biotechnological applications including the phytoremediation of industrial wastes.

Carbon air pollution reflected in deposits on chosen building materials of Prague Castle.

Thin black surface layers or black coloured gypsum crusts can be observed on stones of many buildings and sculptures around the world. The black weathered stone and mortar surface from selected sections of the Prague Castle were studied by microscopic methods, GC/MS and pyrolysis-GC/MS analysis. Microscopically, we found an authigenic gypsum formation with an outer layer of an admixture of fine grains of quartz, clay minerals, thermally altered clay minerals, fly ash, and carbonaceous particles of natural and anthropogenic origin particularly chars, cokes, soots. Noncarbonate C content ranged between 0.8% and 4.3%. Phtalates dominated in extracts from the samples and benzonitrile had the greatest abundance in the pyrolysis products. The identified organic particles and compounds are known to result from human activities.

Seasonal features of aerosol particles recorded in snow from Mt. Qomolangma (Everest) and their environmental implications.

To assess the seasonality of aerosol deposition and anthropogenic effects on central Himalayas, a 1.85-m deep snow pit was dug on the northern slope of Mt. Qomolangma (Everest). Based on the morphology and energy dispersive X-ray (EDX) signal, totally 1500 particles were classed into 7 groups: soot; aluminosilicates; fly ash; calcium sulfates; Ca/Mg carbonates; metal oxides; and biological particles and carbon fragments. The size distribution and number fractions of different particle groups exhibited distinct seasonal variations between non-monsoon and monsoon periods, which are clearly related to the differences in air mass pathways. Specifically, the relative abundance of soot in non-monsoon period (25%) was much higher than that in monsoon period (14%), indicating Mt. Qomolangma region received more anthropogenic influence in non-monsoon than monsoon period.

Efeito da temperatura dos moldes de silicones na precisão de troquéis de gessos dos tipos IV e V / Effect of the temperature of silicone impressions on the precision of type IV and V gypsum dies

As alterações dimensionais dos moldes de silicone podem decorrer das variações de temperatura inerentes ao procedimento de moldagem. Os moldes podem ser resfriados ao serem removidos da boca para a bancada de trabalho. Este estudo avaliou o efeito da temperatura dos moldes de silicones na precisão de troquéis de gessos tipos IV e V. Moldes elastoméricos padronizados foram vazados para produzir troquéis de gessos dos tipos IV e V. Os moldes (n=10) foram confeccionados com silicones Adsil® Vigodent, Express®3M Espe, Zeta Plus® e Oranwash® L Zhermack, pela técnica de dupla moldagem, à temperatura de 35ºC e armazenados a 22ºC. Um grupo recebeu vazamento de gessos tipos IV e V à temperatura de 22ºC, enquanto no outro grupo os moldes foram reaquecidos a 35ºC e vazados com os mesmos gessos. A dimensão da largura dos corpos-de-prova foi medida em milímetros, usando microscópio comparador digital (Mitutoyo).As médias de cada grupo foram comparadas pelos testes de Kruskal-Wallis e Mann-Whitney. Foi observado efeito significativo do material de moldagem, quando o vazamento foi feito com gesso tipo IV, a 22ºC (p<0,001)e a 35ºC (p=0,003). Os efeitos do tipo de gesso e da temperatura foram significativos para todos os materiais estudados (p<0,001). A técnica de reaquecimento de moldes produziu modelos de gesso tipo IV com dimensões similares àqueles obtidos de moldes vazados com gesso do tipo V, à temperatura ambiente.

Back-scattered electron imaging and elemental microanalysis of retrieved bone tissue following maxillary sinus floor augmentation with calcium sulphate.

OBJECTIVES: To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS). MATERIAL AND METHODS: Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material. RESULTS: Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio > or =2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11-2.4) and C, mainly calcium phosphate (S/P< or =0.11; C), which had a mean Ca : P ratio of 1.63+/-0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process. CONCLUSIONS: CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone.