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1.
J Mech Behav Biomed Mater ; 116: 104336, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33540325

RESUMO

Orthodontic chains are one of the main parts of orthodontic braces. In this study, in order to obtain a suitable polymer for this application as well as troubleshoot the main drawbacks such as stress relaxation and water absorption, thermoplastic polyurethane (TPU) elastomers with various compositions were synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analyses. Mechanical properties of samples were evaluated by tensile, elasticity, and stress relaxation tests. According to the required properties for orthodontic chain application, PU2000-311 which contains reversible crosslinks, was selected as the most favorable sample among other pure samples. Moreover, to reduce the water absorption content of PU2000-311, its nanocomposite containing 1 wt% of silica nanoparticles was prepared via solution casting method. As water content angle and field emission scanning electron microscopy (FESEM) images illustrate, incorporation of 1 wt% of modified silica nanoparticles has increased PU2000-311-1S hydrophobicity. In vitro oral environment study showed crystability of samples has recovered great portion of relaxed force. Stress relaxation study indicated samples are applicable in oral temperature range and temperature changes have assisted recovery of relaxed force and reduced treatment period. Finally, shape memory study showed that optimum samples could recover 100% of their original shape.

2.
Ecotoxicol Environ Saf ; 210: 111862, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33429321

RESUMO

Microcystin-leucine arginine (MC-LR) is a carcinogenic toxin, produced by cyanobacteria. The release of this toxin into drinking water sources can threaten public health and environmental safety. Therefore, effective MC-LR removal from water resources is necessary. In the present study, the hydrothermal method was used to synthesize a novel ternary BiVO4/TiO2/NaY-Zeolite (B/T/N-Z) nanocomposite for MC-LR degradation under visible light. FESEM, FTIR, XRD, and DRS were performed for characterizing the nanocomposite structure. Also, the Response Surface Methodology (RSM) was applied to determine the impact of catalyst dosage, pH, and contact time on the MC-LR removal. High-performance liquid chromatography was performed to measure the MC-LR concentration. Based on the results, independent parameters, including contact time, catalyst dosage, and pH, significantly affected the MC-LR removal (P < 0.05). In other words, increasing the contact time, catalyst dosage, and acidic pH had positive effects on MC-LR removal. Among these variables, the catalyst dosage, with the mean square and F-value of 1041.37 and 162.84, respectively, had the greatest effect on the MC-LR removal efficiency. Apart from the interaction between the catalyst dosage and contact time, the interaction effects of other parameters were not significant. Also, the maximum MC-LR removal efficiency was 99.88% under optimal conditions (contact time = 120 min, catalyst dosage = 1 g/L, and pH = 5). According to the results, the B/T/N-Z nanocomposite, as a novel and effective photocatalyst could be used to degrade MC-LR from polluted water.


Assuntos
Luz , Toxinas Marinhas/química , Microcistinas/química , Nanocompostos/efeitos da radiação , Titânio/efeitos da radiação , Vanadatos/efeitos da radiação , Poluentes Químicos da Água/química , Ítrio/efeitos da radiação , Zeolitas/efeitos da radiação , Bismuto/química , Catálise , Nanocompostos/química , Processos Fotoquímicos , Titânio/química , Vanadatos/química , Purificação da Água/métodos , Ítrio/química , Zeolitas/química
3.
Prog Orthod ; 22(1): 2, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33409700

RESUMO

BACKGROUND: The aim of this study was to investigate the effect of surface roughening and acid etching on clinical success rate and removal and insertion torque of orthodontic miniscrews. MATERIALS AND METHODS: Sixty-two orthodontic miniscrews (Jail Medical Corporation, Seoul, Korea) with the same design and dimensions (10-mm length, 2-mm diameter) are divided into two (sandblasted and acid-etched versus control) groups. The sample of the study was 31 patients whose miniscrews were needed for en masse retraction of the upper six anterior teeth. In this split-mouth study, the miniscrews were placed in the attached gingiva between the second premolar and the first molar. The side (left or right) was selected randomly. The miniscrews were loaded 6 weeks after insertion, and the patients were followed up after 3, 6, 10, 14, and 18 weeks and then for 4 weeks interval. Chi-square, correlation, and independent t tests were done using SPSS ver24 to interpret the data. RESULTS: The survival rate was 90.3% and 83.9% for the sandblasted and acid-etched versus the control group, respectively. The difference in survival rate was not statistically significant (p > 0.05). Removal torque was higher for the sandblasted group (p < 0.05). Younger patients showed less survival rate (p < 0.05) in both groups. Insertion side, namely, left or right, was not statistically significant. CONCLUSIONS: Although sandblasting increased removal torque, it did not influence the survival rate of orthodontic miniscrews significantly.


Assuntos
Procedimentos de Ancoragem Ortodôntica , Parafusos Ósseos , Humanos , Boca , Desenho de Aparelho Ortodôntico , Taxa de Sobrevida , Torque
4.
Artigo em Inglês | MEDLINE | ID: mdl-33052509

RESUMO

This study aimed to investigate spatial distribution, correlations among elements and ecological and probabilistic health risk assessment in smaller than 75 µm street dust in Kerman city, Iran. Street dust samples were collected from 35 different points. Elements were detected by ICP-AES. Pollution degree was characterized through Enrichment Factor (EF), Contamination Factor (CF), Geo-accumulation Index (Igeo) and Potential Ecological Risk (PER). The health risk was assessed using the Monte Carlo simulation method. The mean values of elements were in the order of Al > Mn > Zn > Cu > V > Pb > Cr > Ni > Li > As > Co > Mo > Sb > Cd > Ag. The results of Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that Al, As, Co, Li, Mn and V were possibly derived from natural sources (local soil), while traffic and mining activities were proposed as the main source of Cd, Cr, Cu, Mo, Ni, Pb, Sb and Zn. The order of EF and CF mean values decreased as follows: Mn > Ag > Cu > Zn > Pb > Sb > Mo > Li > Co > V > Cd > As > Cr > Ni. In addition, 73% of Cu and 35% of Zn, Ag and Mn had significant enrichment in the street dust samples. Also, Ag and Mn were categorized in the significant and very significant pollution category. In terms of the PER index, all samples could be classified at low-risk category. Ingestion of street dust was the significant route for exposure of residents of Kerman to the elements studied. No significant ecological hazards and health risks were observed from street dust in the study area in the period of the study. The improvement in the fuels quality and development of green spaces can be suggested to control natural and anthropogenic street dust pollution sources in the Kerman city.

5.
Artigo em Inglês | MEDLINE | ID: mdl-33052571

RESUMO

Trihalomethanes (THMs) are one of the most common classes of disinfection by-products. In this study, the temporospatial trends and health risks due to exposure to THMs in the Tabriz water distribution network were investigated. THM series were analyzed using gas chromatography equipped with electron capture detector. The non-carcinogenic and carcinogenic risks due to exposure to THMs were calculated using Monte Carlo simulations. Mean concentrations of THMs in winter and spring were 10.2 ± 9.3 µg/l and 252 ± 185.9 µg/l, respectively. More than 80% of THMs identified were bromodichloromethane. The mean values of lifetime cancer risk (LTCR) of THMs were calculated as 4.23E-06 and 2.38E-04 for winter and spring, respectively. This study showed that there were noticeable levels of THMs in Tabriz water distribution network, especially in the center of the city. Although the non-cancer risk through THMs was below permissible recommended levels, the cancer risk likely remains due to high levels of THMs in some locations.

6.
MethodsX ; 7: 100991, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32714850

RESUMO

Hydrophobic volatile organic compounds (VOCs) such as n-hexane are not completely biodegradable by a single biofilter. So, in the present study, a photoreactor system packed with scoria granules coated with TiO2, as a pretreatment unit, was used for increasing the removal efficiency of n-hexane by a biofilter during an operation period of 191 days. The inlet and outlet concentration of n-hexane was analyzed with a gas chromatography coupled with a flame ionization detector (GC/FID). The results indicated that the removal efficiency of the single biofilter with input concentrations of 0.18 - 1 g/m3 at empty bed residence times (EBRTs) of 30, 60, and 120 s was 10.06%, 21.45%, and 46.8%, respectively. When the photoreactor was used as a pretreatment system, the removal efficiency of the combined system in corresponding EBRTs was improved to 39.79%, 63.08%, and 92.60%, respectively. The results proved that the combined system provided higher removal efficiencies than the single biofilter. Thus, the application of the photoreactor as a pretreatment step was much effective in increasing the removal efficiency of n-hexane from the polluted air by the biofilter.

7.
Environ Sci Pollut Res Int ; 27(30): 38004-38014, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32617810

RESUMO

The present study aimed to survey the spatial and temporal trends of ambient concentration of PM2.5 and to estimate mortality attributed to short- and long-term exposure to PM2.5 in Isfahan from March 2014 to March 2019 using the AirQ+ software. The hourly concentrations of PM2.5 were obtained from the Isfahan Department of Environment and Isfahan Air Quality Monitoring Center. Then, the 24-h mean concentration of PM2.5 for each station was calculated using the Excel software. According to the results, the annual mean concentration of PM2.5 in 2014-2019 was 29.9-50.9 µg/m3, approximately 3-5 times higher than the WHO guideline (10 µg/m3). The data showed that people of Isfahan in almost 58% to 96% of the days of a year were exposed to PM2.5 higher than the WHO daily guideline. The concentrations of PM2.5 in cold months such as October, November, December and January were higher than those in the other months. The zoning of the annual concentrations of PM2.5 in urban areas showed that the highest PM2.5 concentrations were related to the northern, northwestern, southern and central areas of the city. On average, from 2014 to 2019, the number of deaths due to natural mortality, lung cancer (LC), chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD) and stroke associated with ambient PM2.5 were 948, 16, 18, 281 and 60, respectively. The present study estimated that on average, 14.29% of the total mortality, 17.2% of lung cancer (LC), 15.54% of chronic obstructive pulmonary disease (COPD), 17.12% of ischemic heart disease (IHD) and 14.94% of stroke mortalities were related to long-term exposure to ambient PM2.5. So provincial managers and politicians must adopt appropriate strategies to control air pollution and reduce the attributable health effects and economic losses.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Cidades , Exposição Ambiental , Irã (Geográfico) , Mortalidade , Material Particulado/análise
8.
ACS Omega ; 5(7): 3131-3143, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32118129

RESUMO

One of the serious problems in the oil industry is precipitation and deposition of asphaltenes in the different oil production stages including formation, wellbore, production tubing, flow lines, and separation units. This phenomenon causes a dramatic increase in the cost of oil production, processing, and transferring. Thus, it seems to be very necessary to use the removing methods for precipitated asphaltenes in different crude oil production and transferring stages. In this study, the ability of microorganisms for biodegradation of precipitated asphaltenes was investigated. For this purpose, four bacterial consortiums were isolated from oil-contaminated soil, crude oil, reservoir water, and oil sludge samples of an oil field located in the southwest of Iran. Based on the results of the designed experiments, by using response surface methodology (RSM) and central composite design, the bacterial consortiums were cultured in the flasks. Three levels of temperatures, salinity, pH, and initial asphaltene concentration as the substrate were considered as the parameters of culture medium and incubated growth mediums for 60 days. The maximum asphaltene biodegradation was 46.41% caused by the crude oil consortium including Staphylococcus saprophyticus sp. and Bacillus cereus sp. at 45 °C, salinity 160 g·L-1, pH 6.5, and 25 g·L-1 initial asphaltene concentration. Also, it was observed that the negative or positive impacts of culture media conditions such as temperature and salinity on asphaltene degradation depended on the type of the available bacterial consortium. The carbon-hydrogen-nitrogen-sulfur analysis showed that carbon, hydrogen, nitrogen, and in some cases, the sulfur in biodegraded samples are less than in control samples. Moreover, Fourier transform infrared analysis indicated that the alkyne groups were less resistant to biodegradation and were eliminated thoroughly after 2 months of incubation. In addition, alkane components were partially removed in treated asphaltene fraction. The parameters of culture medium were optimized by RSM, and besides, their effects on the performance of bacteria in the asphaltene biodegradation process were discussed. The validity of some available kinetic models to describe the behavior of the studied bacteria consortium was investigated, and it was observed that Tessier, Moser, and Contois models accurately predict the values of asphaltenes and biomass concentration at 30, 45, and 60 °C, respectively.

9.
Ecotoxicol Environ Saf ; 192: 110286, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32036101

RESUMO

Trihalomethanes (THMs) in drinking water are associated with many chemical parameters in water. However, the available evidence on the relationship between physical parameters of the water distribution system (WDS) and THMs is still scarce; therefore, this study aimed to compare the THMs concentration in the old and new WDS in Yazd, Iran. Moreover, we investigated the seasonal trend and health risk assessment of exposure to THMs through ingestion, dermal, and inhalation pathways. Mann-Whitney test was applied to compare THMs between old and new WDS as well as fall season and winter season. The order of THM concentrations was: chloroform > BDCM > DBCM > bromoform. The maximum levels of THMs in the fall and winter were 31 and 39 ppb, respectively, which were less than the WHO recommended limits for drinking water, i.e., <200 ppb. There was a significant difference between the concentration of BDCM in autumn and winter (P-value = 0.01). There was a marginally significant difference between THM concentration in the autumn and winter (P-value 0.09). The total concentration of THMs and chloroform in the old WDS were significantly higher than the new WDS. The mean values of lifetime cancer risks (LTCR) for oral, dermal, and inhalation exposure pathways to THMs were in the acceptable and low-risk levels. The inhalation exposure pathway had the highest LTCR from among the three mentioned exposure pathways. The hazard index was found to be < 1 through oral and dermal pathways. Moreover, the sensitivity analysis revealed that the ingestion rate for oral exposure, the exposure time for dermal and exposure duration for the inhalation exposure pathway had the highest impact on chronic daily intake (CDI). Our finding confirmed that THM concentration in tap water was associated with the lifespan of WDS and this finding could be useful for urban planners and decision-makers.


Assuntos
Água Potável/química , Trialometanos/análise , Poluentes Químicos da Água/análise , Derme , Exposição Dietética , Exposição Ambiental , Humanos , Exposição por Inalação , Irã (Geográfico)/epidemiologia , Neoplasias/epidemiologia , Probabilidade , Medição de Risco , Estações do Ano , Abastecimento de Água
10.
Chemosphere ; 246: 125769, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31918090

RESUMO

Land Use Regression models (LUR) are the most common tools to estimate intra-urban air pollutant exposure in epidemiological studies. However, number of available and published models in developing and middle up income countries is still scarce. Here, we developed seasonal and overall LUR models for the spatial distribution of benzene, toluene, ethylbenzene and xylene (BTEX) based on 20 monitoring stations and 166 potentially predictive variables (PPVs) in Urmia, Iran. Carcinogenic and non-carcinogenic risks of exposure to BTEX and its sensitivity analysis were assessed using a probabilistic approach. The mean and standard deviation (in brackets) of overall benzene, toluene, ethylbenzene and xylene were 12.83 (16.19), 27.03 (32.00), 4.72 (4.15) and 27.35 (29.36) µg/m3, respectively. In all models the R2 value of LUR models of benzene, toluene, ethylbenzene, xylene and total BTEX ranged from 0.66 to 0.85, 0.61, 0.88, 0.72 to 0.94, 0.75 to 0.84 and 0.67 to 0.93. The root mean square error (RMSE) for leave-one-out cross-validations (LOOCV) for benzene, toluene, ethylbenzene and xylene ranged from 7.48 to 10.31, 23.0 to 30.0, 3.40 to 6.90, 16.27 to 24.49, 36.10-50.0 µg/m3, respectively. The estimated lifetime carcinogenic risk (LTCR) indicated that ambient concentration of benzene is at a risk level for Urmia inhabitants (LTCR >10-6). Sensitivity analysis for LTCR model indicated that concentration of benzene (C) was the most effective variable in increasing the carcinogenic risk (correlation coefficient ranged from 0.97 to 0.98 for all models).


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Benzeno/análise , Derivados de Benzeno/análise , Carcinógenos/análise , Humanos , Irã (Geográfico) , Medição de Risco , Análise Espacial , Tolueno/análise , Xilenos/análise
11.
Braz. dent. sci ; 23(4): 1-8, 2020. ilus, tab
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1122559

RESUMO

Objective: The objective of this study was to determine whether recently developed fiber reinforced composite burs provided better results by comparing tooth discoloration after debonding of orthodontic brackets. Material and Methods: A split-mouth, randomized controlled trial was carried out in one orthodontic office; including 23 patients with intact, vital and caries-free four upper incisors aged 12 to 30 years who completed their fixed orthodontic treatment. For each patient, upper central and lateral incisors on each side of the mouth were randomly selected to remove the adhesive with either a tungsten carbide bur (TC) (n = 46) or a fiber-reinforced composite bur (FC) (n=46). Color evaluation of each tooth was conducted at two time points: immediately after finishing and polishing procedure and two months afterwards. The primary outcome would be the amount of color change in each group during the post treatment phase. The participants, the person assessing the color change and the statistician were blinded to TC group assignment. Color changes in each group were analyzed with the Paired T-test. The color change corresponding to the resin removal method was also statistically analyzed with the Independent T-test at α=0.05 as the level of significance. Results: 86 teeth, 43 in each group, were analyzed. The ΔE value was 3.713±1.161, for teeth finished TC and 2.114±0.514 for teeth finished with FC (p<0.01). Conclusion: Adhesive removal with FC bur results in a more color-resistant tooth surface in comparison with tungsten carbide bur. (AU)


Objetivo: O objetivo deste estudo foi determinar se as brocas de material compósito reforçadas com fibras, recentemente desenvolvidas, proporcionam melhores resultados, pela comparação da descoloração dentária após a remoção de braquetes ortodônticos. Material e Métodos: Um ensaio clínico controlado randomizado com boca dividida foi realizado em um consultório ortodôntico, incluindo 23 pacientes, com idade entre 12 e 30 anos, com incisivos superiores intactos, vitais e livres de cárie, que completaram o tratamento ortodôntico com aparelho fixo. Para cada paciente, incisivos centrais e laterais superiores de cada lado da boca foram selecionados aleatoriamente para remover o adesivo ortodôntico com uma broca carbide de tungstênio (TC) (n = 46) ou uma broca de compósito reforçada com fibra (FC) (n = 46). A avaliação da cor de cada dente foi realizada em dois momentos: imediatamente após o acabamento e polimento e dois meses após. O resultado primário foi a quantidade de mudança de cor em cada grupo durante a fase pós-tratamento. Os participantes, a pessoa que avaliou a mudança de cor e o estatístico não tinham conhecimento da atribuição ao grupo TC. As mudanças de cor em cada grupo foram analisadas com o teste-t pareado. A mudança de cor correspondente ao método de remoção da resina também foi analisada estatisticamente com o teste-t independente considerando um nível de significância α = 0,05. Resultados: foram analisados 86 dentes, 43 em cada grupo. O valor de ΔE foi 3,713 ± 1,161, para dentes finalizados com broca TC e 2,114 ± 0,514 para dentes finalizados com broca FC (p <0,01). Conclusão: A remoção do adesivo com broca FC resulta em uma superfície de dente mais resistente à cor em comparação com a broca carbide de tungstênio (AU)


Assuntos
Humanos , Adulto , Descoloração de Dente , Descolagem Dentária , Aparelhos Ortodônticos Fixos
12.
J Safety Res ; 71: 273-284, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31862039

RESUMO

INTRODUCTION: Construction incidents occur due to system failures, not due to a single factor such as unsafe behavior or condition. Therefore, construction safety should be investigated using a systematic view capable of illustrating the complex nature of incidents. Construction projects are also often behind their planned schedule and suffer from various pressures caused by contractual deadlines or clients. Previous studies demonstrated that such pressures negatively affect safety performance; however, the process of how production pressure influences safety performance is not fully investigated. METHOD: The present research aimed to understand the feedback mechanism of how production pressure interactively affects safety performance and safety-related managerial components in a construction project. Ground theory method (GTM) is used to create a conceptual causal loop diagram that shows the relationship between incident rate and other variables such as labor hour, actual and planned progress, safety climate, rework, and safety training. Moreover, a power plant construction project was used as a case study to practically investigate the conceptual model; a case study is employed to build a System Dynamics (SD) model. The simulation model was then validated using behavior reproduction and sensitivity analysis. RESULTS: The results of the inequality statistics show that the simulation model can be used to forecast trends in the incident rate.


Assuntos
Indústria da Construção/estatística & dados numéricos , Saúde do Trabalhador/estatística & dados numéricos , Centrais Elétricas , Gestão da Segurança/métodos , Humanos , Modelos Teóricos
13.
MethodsX ; 6: 1694-1700, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31388504

RESUMO

In northwest of Iran, airborne particulate matter originated from drying Urmia Lake is threaten the health of surrounding communities due to salt particles and heavy metals. This study aimed to use leave of local trees for biomonitoring of toxic metals and to evaluate tolerance of the trees against air pollution due to greenbelt development. Leaf samples were taken from four dominant tree species including Vitis vinifera, Juglans regia, Ulmus umbraculifera and Popolus alba in two radial distances (5 and 10 km) around the Urmia Lake in 32 sampling sites. The concentration of Cd, Pb, Ni, As, Cu, Zn and Na in the leaves were extracted according to method 3050B defined by United States Environmental Protection Agency (USEPA) and analyzed by ICP-AES technique. According to the levels of air pollution tolerance index (APTI), Popolus. alba was classified as more sensitive and Vitis. vinifera as moderately tolerant. The accumulation/existence of metals in the leaves can be arranged as follows: Na > Zn > Cu > Ni > Pb > As > Cd. Our findings showed that Popolus. alba can be applied as a local biomonitor and Vitis. vinifera can be used as a good sink of air pollutants for greenbelt development around the drying Urmia Lake. •The results show that APTI is a suitable index for selection of tree species as biomonitor and green belt development.•Determination of metal concentration level in local tree leaves is suggested as a good tool for mapping of airborne metal.•The local trees can be suitable for development of greenbelt in order to improve air quality, and also for biomonitoring of air pollution.

14.
J Control Release ; 307: 150-165, 2019 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-31229474

RESUMO

While the advent of nano-engineered drug delivery systems (DDSs) has revived hopes for better management of a wide range of pathologies, critical appraisal of the field has shown that further improvement of nanomedicine demands a paradigmatic shift in design and development approaches currently employed by drug developers. In this review, we portray various theoretical modeling frameworks as influential tools to furnish future design and development of DDSs. The rational design of nanomedicines should be premised on taking into account the sui generis nature of DDSs within a multiplex biological milieu in vivo. Technical limitations, however, remain a bottleneck to the faithful reconstruction of such biomimetic models. Computational and mathematical modeling tools have shown potential as a promising technique to broaden the horizon of nanomedicine by addressing blind spots of current empirical models. Through integration with modern imaging and microfluidic technologies, in silico modeling is expected to expedite the clinical translation of nanomedicine.


Assuntos
Sistemas de Liberação de Medicamentos , Modelos Teóricos , Nanopartículas/administração & dosagem , Simulação por Computador , Desenho Assistido por Computador , Humanos , Nanomedicina
15.
MethodsX ; 6: 760-763, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31011549

RESUMO

The Trihalomethanes (THMs) formed due to a reaction between water disinfection chlorine and some natural organic matters, as chlorinated by products. The aim of this study was determination of THMs values and spatial trend in Yazd city water distribution network, in center of Iran. Sampling of tap water was done in two autumn and winter seasons. The THMs value were measured by using a gas chromatograph-mass spectrometer (GC/MS), Agilent Company 6890 N. The spatial analysis of THMs values was carried out using ArcGIS 10.1 to show the spatial spreading. The Kriging method was used to draw distribution maps. Using the Kriging method to illustrate the difference or precision of forecasts is relatively easy compared to the other interpolation methods. Also, the acceptable level of % RMSE (Root mean square error) was calculated for Kriging method (% RMSE > 40). Thus, this protocol as integrated between data and geraphic could easily used for reporting of THMs level in studies of water distribution network. Finally, the maximum THMs value were obtained lower than USEPA and WHO guidelines for drinking water (THMs < 40 ppb).

16.
MethodsX ; 6: 156-161, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30733928

RESUMO

Air pollutants are capable to enter bloodstream through the nose, mouth, skin and the digestive tract. Hemolysis is the premature destruction of red blood cells (RBCs) membranes. This can affect metabolism of RBCs and reduce cell life. Each of these adverse effects could lead to anemia, jaundice and other pathological conditions. Hemolysis can induce by the mineral components adsorbed on the particles. The aim of this study was to evaluate hemolysis of RBCs treated by airborne PM10 (PM with aerodynamic diameter ≤ 10 µm) in vitro. Study had two main stages including sampling and preparation of PM10 suspension, and hemolysis test. Particle samples were collected by means of a high-volume sampler on fiberglass filters. The PM10 was extracted through dry ultrasonic method. Blood sample was incubated by PM10 at concentrations 50-300 µg/mL for 3 h. Hemolysis percent was assessed through measurement of Hemoglobin concentration in test samples and total blood hemoglobin (TBH) sample by the cyanmethemoglobin method. Analysis of variance (ANOVA) and Tukey post-hoc test were applied to compare mean values of hemolysis percent between different PM concentrations. Method used in current study is suggested for investigation of toxic effects of airborne particle matter (PM1, PM2.5 and PM10) on human RBCs.

18.
J Safety Res ; 67: 17-26, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30553420

RESUMO

INTRODUCTION: Safe behavior and work conditions are a major concern in construction projects. However, accidents occur due to system failures, not a single factor such as unsafe behavior or condition. Construction safety should be investigated by a systematic view capable of illustrating the complex nature of accidents. METHOD: The present research aims to detect and categorize behavior patterns recurring in construction safety management continuously. Content analysis and ground theory method (GTM) were adopted to achieve the study objectives. In total, 90 articles were reviewed to explore the factors influencing safety in construction projects all over the world. Furthermore, 20 interviews were conducted on participants with rich experience in construction health and safety. Four archetypes were identified from data collection process, including delay in design, number of subcontractors, cost and safety of project, and supervisors and safety. Each archetype is completely discussed at different steps of dynamic complexity, behavior over time, and the leverage point to show how to deal with the archetype.


Assuntos
Acidentes de Trabalho/prevenção & controle , Indústria da Construção , Saúde do Trabalhador , Gestão da Segurança/métodos , Humanos , Análise de Sistemas
19.
J Environ Manage ; 224: 58-68, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-30031919

RESUMO

Gas adsorption on various adsorbents is of highly important issue for the separation of gas mixtures in many industrial processes. In this work, estimation of pure gases (CH4, N2, CO2, H2, C2H4) adsorption on activated carbon (AC) and CO2, CH4, N2 on Zeolite-5A adsorbent were studied by developing four different computing techniques, namely MLP-ANN, ANFIS, LSSVM, and PSO-ANFIS for a broad range of experimental data found in the literature. Temperature, pressure, pore size (only for AC) and kinetic diameter of adsorbed gases are considered as the inputs and the gas adsorption as the output parameters of the developed models. We also used several statistical and graphical tools to assess the accuracy and applicability of the proposed models. The results of the study suggest the reliability and validity of all the models developed for estimating the equilibrium adsorption of gases on the adsorbents. Also, it is found that of all the models developed, the ANN model estimates experimental data of the gas adsorption on AC more accurately due to its values of R2 and AARD%, 0.9865 and 0.8948, respectively. Besides, PSO-ANFIS is the best model to prognosticate gas adsorption on zeolite 5A with R2 and AARD%, 0.9897 and 0.9551, respectively.


Assuntos
Dióxido de Carbono , Zeolitas , Adsorção , Carbono , Gases , Reprodutibilidade dos Testes
20.
J Clin Exp Dent ; 10(6): e548-e554, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29930773

RESUMO

Background: Amount of pressure exerting on orthodontic brackets during bonding can create different thickness of adhesive and affect shear bonding strength(SBS) in different adhesive systems. The purpose of this study was to evaluate the effect of different force magnitudes for placement of brackets on SBS. Material and Methods: In an in vitro study, 420 brackets were placed on the bovine teeth, using three types of adhesives, Concise (chemically cured two-paste mix), Unite (chemically cured no mix), and Transbond XT( light cured), with the application of seven force magnitudes of 50, 100, 200, 300, 400, 600 and 1000 grams in twenty-one groups of twenty samples each. SBS means (using two-way ANOVA with Tukey's post-hoc test) and adhesive remnant index were compared between these twenty-one groups. Results: SBS increased with an increase in force. No increase in Transbond XT SBS happened after 400 grams. In addition, Transbond XT had the lowest bond strength among three adhesives (p<0.001). Adhesive remnant index (ARI) results also indicated a shift in the failure mode from bracket-adhesive interface to adhesive-enamel interface, as the bonding force got heavier (p<0.05). Conclusions: The force applied on bracket during bonding influences the SBS. In order to have higher bond strength, application of heavy force would be advisable. It is also recommended that constant forces be applied for bracket bonding in future studies. Key words:Adhesive, ARI, Bonding procedures, SBS, shear bond strength.

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