This paper describes a prototype instrumentation system for photogrammetric measuring of bed and ash layers, as well as for flying particle detection and pursuit using a single device (CCD) web camera. The system was designed to obtain images of the combustion process in the interior of a domestic boiler. It includes a cooling system, needed because of the high temperatures in the combustion chamber of the boiler. The cooling system was designed using CFD simulations to ensure effectiveness. This method allows more complete and real-time monitoring of the combustion process taking place inside a boiler. The information gained from this system may facilitate the optimisation of boiler processes.
biomass boiler; web camera; photogrammetric processing; CFD analysis
Emission samples were obtained from two medium-sized power plants, one fired with oil and the other with pulverized coal. Particles obtained by a miniscale plume stack gas sampler (MIPSGAS), simulating the dilution process in the plume, were subjected to detailed physical, chemical and biological characterization. Studies by scanning electron microscopy and by Coulter counter demonstrated that the particles from the oil-fired boiler were considerably larger than the particles from the coal-fired boiler. Chemical analyses revealed more organic substances and more S, Ni, V, in the oil than in the coal particles. The latter contained a larger proportion of Al, Si, Cl, K, Ca, Ti, Mn, Fe, Se, Rb, Y, Zr, Ba and Pb. Biological testing revealed a greater acute and subacute toxicity by the intratracheal route in the hamster, a greater toxicity to alveolar macrophages and a greater lung retention of BaP coated on the particles from oil combustion than on those from coal combustion. In another sampling line, employed simultaneously with the MIPSGAS-particulate sampler, the total emissions were collected, i.e., both particle and gas phase. These samples were used for chemical analyses and Ames mutagenicity test. Analyses of specific PAHs in emissions from both plants demonstrated that concentrations were below the detection limit (less than 4 ng/m3 of benzo(a)pyrene), which is in accord with an efficient combustion of the fuel. The mutagenicity of the samples were below the detection limit of the mutagenicity assay.
The present study aimed to measure root surface roughness in teeth with periodontitis by a profilometer following root planning with ultrasonic and hand instruments with and without erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation.
Sixty single-rooted maxillary and mandibular teeth, extracted because of periodontal disease, were collected. The crowns and apices of the roots were cut off using a diamond bur and water coolant. The specimens were mounted in an acrylic resin block such that a plain root surface was accessible. After primary evaluation and setting a baseline, the samples were divided into 4 groups. In group 1, the samples were root planned using a manual curette. The group 2 samples were prepared with an ultrasonic scaler. In group 3, after scaling with hand instrumentation, the roots were treated with a Smart 1240D plus Er:YAG laser and in group 4, the roots were prepared with ultrasonic scaler and subsequently treated with an Er:YAG laser. Root surface roughness was then measured by a profilometer (MahrSurf M300+RD18C system) under controlled laboratory conditions at a temperature of 25℃ and 41% humidity. The data were analyzed statistically using analysis of variance and a t-test (P<0.05).
Significant differences were detected in terms of surface roughness and surface distortion before and after treatment. The average reduction of the surface roughness after treatment in groups 1, 2, 3, and 4 was 1.89, 1.88, 1.40, and 1.52, respectively. These findings revealed no significant differences among the four groups.
An Er:YAG laser as an adjunct to traditional scaling and root planning reduces root surface roughness. However, the surface ultrastructure is more irregular than when using conventional methods.
Laser therapy; Periodontitis; Tooth; Ultrasonics
OBJECTIVES: Dental instruments such as the right angle or straight handpiece, air turbine, and ultrasonic scaler have the ability to produce dental aerosols containing water, saliva, microorganisms, blood, tooth particles, lubricating oil, and restorative materials. The purpose of this study was to find out whether personal protective equipment (mask, glasses) was used by dental personnel, and to investigate possible work related disease in the dental profession. METHODS: Cross sectional data were collected with a self administered questionnaire sent to 69 randomly chosen general dental practices in the West Midlands Region. All members of the dental team completed questionnaires (dentists (n = 122); nurses (n = 115); hygienists (n = 86); and receptionists (n = 74) and answered questions on use of personal protective equipment and the prevalence of upper and lower respiratory tract, eye, and skin symptoms (reported and work related). Reception staff were included as a low exposure, control group. Also, a longitudinal study of dental hygienists was carried out on 31 people who had taken part in a similar study five years earlier. RESULTS: Use of a face mask and glasses differed between clinical groups with hygienists and nurses being the most and least prevalent users respectively. Although several reported symptoms were significantly more prevalent among clinical staff, only one work related symptom (skin rashes or itchy or dry skin) was reported by the clinical staff more than by the non-clinical receptionists. Among female clinical staff, age < 35 years and atopy were the factors that predisposed to work related symptoms. Also, reported symptoms were related to duration of use of instruments that generated aerosols. CONCLUSIONS: This study shows a low level of work related symptoms in dentistry, but highlights a group vulnerable to prolonged exposures to dental aerosols. It also supports the need for enforcement of the use of personal protective equipment among dental nurses.
OBJECTIVES: The cancer incidence among 2957 boiler welders was investigated. The subjects were registered electrical welders from 1942 to 1981. A subcohort of 606 stainless steel welders was studied separately. METHODS: The investigation was a historical prospective cohort study based on a national registry. The loss of follow up was 4.9%. RESULTS: There were 625 deaths (659 expected). There were 269 cancer cases (264 expected). An excess of lung cancer was found; 50 cases v 37.5 expected. There were three cases of pleural mesotheliomas v 1.1 expected. The subcohort of stainless steel welders had six cases of lung cancer v 5.8 expected, and one case of pleural mesothelioma v 0.2 expected. CONCLUSIONS: The welders in the study were assumed to represent a qualified work force. These welders had a small excess risk of lung cancer. The excess risk did not seem to be associated with stainless steel welding. Smoking and asbestos exposure were potential confounders.
The use of appropriate instruments to clean surfaces with minimal change, is critical for the successful maintenance of a dental implant. However, there is no consensus about the type and methodology for such instruments. The aim of this study was to characterize changes in the roughness of titanium surfaces treated by various scaling instruments.
Thirty-seven identical disks (5 mm in diameter) were investigated in this study. The specimens were divided into eight groups according to the types of instrumentation and the angle of application. Ultrasonic scaling systems were applied on a titanium disk to simulate standard clinical conditions. The equipment included a piezoelectric ultrasonic scaler with a newly developed metallic tip (NS group), a piezoelectric ultrasonic scaler with a conventional tip (CS group), a piezoelectric root planer ultrasonic scaler with a conventional tip (PR group), and a plastic hand curette (PH group). In addition, the sites treated using piezoelectric ultrasonic scaler systems were divided two sub-groups: 15 and 45 degrees. The treated titanium surfaces were observed by scanning electron microscopy (SEM), and the average surface roughness (Ra) and mean roughness profile depth (Rz) were measured with a profilometer.
SEM no significant changes in the titanium surfaces in the NS group, regardless of the angle of application. The PH group also showed no marked changes to the titanium surface, although some smoothening was observed. All CS and PR sites lost their original texture and showed irregular surfaces in SEM analysis. The profilometer analysis demonstrated that the roughness values (Ra and Rz) of the titanium surfaces increased in all, except the PH and NS groups, which showed roughness decreases relative to the untreated control group. The Ra value differed significantly between the NS and PR groups (P<0.05).
The results of this study indicated that changes in or damage to titanium surfaces might be more affected by the hardness of the scaler tip than by the application method. Within the limitations of this study, the newly developed metallic scaler tip might be especially suitable for peri-implant surface decontamination, due to its limited effects on the titanium surface.
Dental implants; Dental instruments; Peri-implantitis; Periodontal debridement
The objective of this study was to evaluate how the vehicles of choice affect the pharmacokinetics of orally administered Fluoranthene [FLA] in rats. Fluoranthene is a member of the family of Polycyclic Aromatic Hydrocarbon chemicals. Fluoranthene exposure to humans may occur as a result of cigarette smoking, consumption of contaminated food and water, heating woods in stoves and boilers, industrial sources such as coal gasification, carbon and graphite electrode manufacturing. Adult male Fisher-344 rats were given single oral doses of 25 and 50 μg/kg FLA in tricaprylin, peanut oil, cod liver oil, Tween 80/isotonic saline (1:5) and 2% Alkamuls-EL620 through gavage. After administration, the rats were housed individually in metabolic cages and sacrificed at 2, 4, 6, 8, 10 and 12 hours post FLA exposure. Blood, lung, liver, small intestine, adipose tissue samples, urine, and feces were collected at each time point. Samples were subjected to a liquid-liquid extraction using methanol, chloroform, and water. The extracts were analyzed by a reverse-phase HPLC, equipped with a fluorescence detector. The results revealed a dose-dependent increase in FLA concentrations in plasma and tissues for all the vehicles used. Plasma and tissue FLA concentrations were greater for peanut oil; cod liver oil, and tricaprylin vehicles compared to Alkamuls (p < 0.05), and Tween 80/isotonic saline (1:5). Most of the FLA administered through peanut oil, cod liver oil and tricaprylin was cleared from the body by 8 hours (90%) and 12 hours (80%) post administration for the 25 μg/kg and 50 μg/kg dose groups, respectively. With both doses employed, the metabolism of FLA was highest when cod liver oil was used as a vehicle and lowest in vehicles containing detergent/water [cod liver oil > peanut oil > tricaprylin > alkamuls > Tween 80/isotonic saline (1:5)]. These findings suggest that uptake and elimination of FLA is accelerated when administered through oil-based vehicles. The low uptake of FLA from Alkamuls and Tween 80/isotonic saline may have been a result of the poor solubility of the chemical. In summary, our findings reiterate that absorption characteristics of FLA were governed by the dose as well as the dosing vehicle. The vehicle-dependent bioavailability of FLA suggests a need for the judicious selection of vehicles in evaluating oral toxicity studies for risk assessment purposes.
Fluoranthene; pharmacokinetics; absorption; tricaprylin; peanut oil; cod liver oil; and Alkamuls
Biomass combustion contributes to the production of ambient particulate matter (PM) in rural environments as well as urban settings, but relatively little is known about the health effects of these emissions. The aim of this study was therefore to characterize airway responses in humans exposed to wood smoke PM under controlled conditions. Nineteen healthy volunteers were exposed to both wood smoke, at a particulate matter (PM2.5) concentration of 224 ± 22 μg/m3, and filtered air for three hours with intermittent exercise. The wood smoke was generated employing an experimental set-up with an adjustable wood pellet boiler system under incomplete combustion. Symptoms, lung function, and exhaled NO were measured over exposures, with bronchoscopy performed 24 h post-exposure for characterisation of airway inflammatory and antioxidant responses in airway lavages.
Glutathione (GSH) concentrations were enhanced in bronchoalveolar lavage (BAL) after wood smoke exposure vs. air (p = 0.025), together with an increase in upper airway symptoms. Neither lung function, exhaled NO nor systemic nor airway inflammatory parameters in BAL and bronchial mucosal biopsies were significantly affected.
Exposure of healthy subjects to wood smoke, derived from an experimental wood pellet boiler operating under incomplete combustion conditions with PM emissions dominated by organic matter, caused an increase in mucosal symptoms and GSH in the alveolar respiratory tract lining fluids but no acute airway inflammatory responses. We contend that this response reflects a mobilisation of GSH to the air-lung interface, consistent with a protective adaptation to the investigated wood smoke exposure.
The objective of this study was to evaluate how the vehicles of choice affect the pharmacokinetics of orally administered Fluoranthene [FLA] in rats. Fluoranthene is a member of the family of polycyclic aromatic hydrocarbon chemicals. Fluoranthene exposure to humans may occur as a result of cigarette smoking, consumption of contaminated food and water, heating woods in stoves and boilers, industrial sources such as coal gasification, carbon and graphite electrode manufacturing. Adult male Fisher-344 rats were given single oral doses of 25 and 50 μg/kg FLA in tricaprylin, peanut oil, cod liver oil, tween 80/isotonic saline (1:5) and 2% Alkamuls-EL620 through gavage. After administration, the rats were housed individually in metabolic cages and sacrificed at 2, 4, 6, 8, 10 and 12 hours post FLA exposure. Blood, lung, liver, small intestine, adipose tissue samples, urine, and feces were collected at each time point. Samples were subjected to a liquid-liquid extraction using methanol, chloroform, and water. The extracts were analyzed by a reverse-phase HPLC, equipped with a fluorescence detector. The results revealed a dose-dependent increase in FLA concentrations in plasma and tissues for all the vehicles used. Plasma and tissue FLA concentrations were greater for peanut oil; cod liver oil, and tricaprylin vehicles compared to Alkamuls (p < 0.05), and tween 80/isotonic saline (1:5). Most of the FLA administered through peanut oil, cod liver oil and tricaprylin was cleared from the body by 8 hours (90%) and 12 hours (80%) post administration for the 25 μg/kg and 50 μg/kg dose groups, respectively. With both doses employed, the metabolism of FLA was highest when cod liver oil was used as a vehicle and lowest in vehicles containing detergent/water [cod liver oil > peanut oil > tricaprylin > alkamuls > tween 80/isotonic saline (1:5)]. These findings suggest that uptake and elimination of FLA is accelerated when administered through oil-based vehicles. The low uptake of FLA from alkamuls and tween 80/isotonic saline may have been a result of the poor solubility of the chemical. In summary, our findings reiterate that absorption characteristics of FLA were governed by the dose as well as the dosing vehicle. The vehicle-dependent bioavailability of FLA suggests a need for the judicious selection of vehicles in evaluating oral toxicity studies for risk assessment purposes.
Fluoranthene; pharmacokinetics; absorption; tricaprylin; peanut oil; cod liver oil; and alkamuls
Occupational and environmental exposures to asbestos remain a public health problem even in developed countries. Because of the long latency in asbestos-related pathology, past asbestos exposure continues to contribute to incident disease. Asbestos most commonly produces pulmonary pathology, with asbestos-related pleural disease as the most common manifestation. Although the pleurae and pericardium share certain histologic characteristics, asbestos-related pericarditis is rarely reported.
We present a 59-year-old man who worked around boilers for almost 30 years and was eventually determined to have calcific, constrictive pericarditis. He initially presented with an infectious exacerbation of chronic bronchitis. Chest radiographs demonstrated pleural and pericardial calcifications. Further evaluation with cardiac catheterization showed a hemodynamic picture consistent with constrictive pericarditis. A high-resolution computerized tomography scan of the chest demonstrated dense calcification in the pericardium, right pleural thickening and nodularity, right pleural plaque without calcification, and density in the right middle lobe. Pulmonary function testing showed mild obstruction and borderline low diffusing capacity.
Based on the patient’s occupational history, the presence of pleural pathology consistent with asbestos, previous evidence that asbestos can affect the pericardium, and absence of other likely explanations, we concluded that his pericarditis was asbestos-related.
Relevance to clinical practice
Similar to pleural thickening and plaque formation, asbestos may cause progressive fibrosis of the pericardium.
asbestos; boiler operators; calcific pericarditis; constrictive pericarditis; extrapulmonary
The intestinal absorption of 57Co vitamin B12 has been measured by counting the radioactivity in the serum, and the effect of the parenteral administration of 1 mg. non-radioactive vitamin B12 two hours after the oral dose has been studied. When parenteral vitamin B12 was not given, the mean radioactivity in the serum was lower in both patients with pernicious anaemia and in control subjects, and the results in the patients with pernicious anaemia were more definitive. There was no significant difference between the results obtained with an Ekco scaler and those with an I.D.L. scaler.
This is the simplest and most convenient method of measuring vitamin B12 absorption. It is suggested that the test be standardized by giving 0·5 μg. 57Co vitamin B12 with a maximal histamine stimulation of intrinsic factor secretion, but without a parenteral dose of non-radioactive vitamin B12. The results are expressed most usefully as a percentage of the administered dose per litre of serum or plasma.
Statistical analyses indicated (i) that the floras of individual samples taken from the depth of sulci with nickel-plated Morse 00 scalers were highly reproducible and representative of the flora present at any given time, (ii) that the different compositions of floras of different people with similar clinical signs were statistically highly significant, and (iii) that floras of different affected sites may differ significantly in some (two of three) people at any one time or may differ from week to week in other people (one of three). Thus the flora composition of individual sites appears to be in dynamic flux, probably in response either to environmental changes or to host responses. There was no evidence that double sampling per se (two single passes with 00 scalers) changed the composition of the flora. Repeat samples taken after 1 week were slightly more similar to the initial samples than were samples taken after 3 weeks.
The mutagenicity of emission samples from three oil-fired and four coal-fired boilers have been compared by using the Salmonella/microsome assay. Very little or no mutagenic activity was observed in samples from five of these boilers. The sample from one oil-fired boiler showed mutagenic activity of about 500 revertants/MJ, and the sample from a coal-fired fluidized bed combustor had an activity of 58,000 revertants/MJ measured with strain TA 98 in the absence of metabolic activation. All samples contained substances that were cytotoxic to the test bacteria, thus making it difficult to obtain linear dose-response curves. Mutagenic activity at low levels may remain undetected due to this toxicity of the samples. Samples with mutagenic activity below the detection limit in the Salmonella test have also been tested for forward mutations at the HGPRT locus in V79 hamster cells. Weak mutagenic effects were detected in two of the samples, whereas the sample from one oil-fired boiler remained negative. In this test, as well as in the Salmonella test, a strong cytotoxic effect could be observed with all samples.
This work describes a large reclaimed water source heat pump system (RWSHPS) and elaborates on the composition of the system and its design principles. According to the characteristics of the reclaimed water and taking into account the initial investment, the project is divided into two stages: the first stage adopts distributed heat pump heating system and the second adopts the combination of centralized and decentralized systems. We analyze the heating capacity of the RWSHPS, when the phase II project is completed, the system can provide hydronic heating water with the supply and return water temperature of 55°C/15°C and meet the hydronic heating demand of 8 million square meters of residential buildings. We make a thermal economics analysis by using Thermal Economics theory on RWSHPS and gas boiler system, it is known that the RWSHPS has more advantages, compared with the gas boiler heating system; both its thermal efficiency and economic efficiency are relatively high. It provides a reference for future applications of the RWSHPS.
To evaluate the shear bond strength of resin luting agent to dentin surfaces cleansed with different agents like pumice, ultrasonic scaler with chlorhexidine gluconate, EDTA and the influence of these cleansing methods on wetting properties of the dentin by Axisymmetric drop Shape Analysis - Contact Diameter technique (ADSA-CD).
MATERIALS AND METHODS
Forty coronal portions of human third molar were prepared until dentin was exposed. Specimens were divided into two groups: Group A and Group B. Provisional restorations made with autopolymerizing resin were luted to dentin surface with zinc oxide eugenol in Group A and with freegenol cement in Group B. All specimens were stored in distilled water at room temperature for 24 hrs and provisional cements were mechanically removed with explorer and rinsed with water and cleansed using various methods (Control-air-water spray, Pumice prophylaxis, Ultrasonic scaler with 0.2% Chlorhexidine gluconate, 17% EDTA). Contact angle measurements were performed to assess wettability of various cleansing agents using the ADSA-CD technique. Bond strength of a resin luting agent bonded to the cleansed surface was assessed using Instron testing machine and the mode of failure noted. SEM was done to assess the surface cleanliness. Data were statistically analyzed by one-way analysis of variance with Tukey HSD tests (α=.05).
Specimens treated with EDTA showed the highest shear bond strength and the lowest contact angle for both groups. SEM showed that EDTA was the most effective solution to remove the smear layer. Also, mode of failure seen was predominantly cohesive for both EDTA and pumice prophylaxis.
EDTA was the most effective dentin cleansing agent among the compared groups.
EDTA; Dental bonding; Microscopy; Electron; Scanning; Wettability; Zinc-oxide Eugenol cement; Shear strength
Our objective was to determine the efficacy of pre-procedural rinsing with chlorhexidine in reducing bacterial aerosol contamination during use of ultrasonic scaler and comparing the efficacy of water, non-tempered chlorhexidine and tempered chlorhexidine in reducing bacterial count in aerosols when used as a pre-procedural rinse.
Materials and Methods:
The study was designed to include 30 systemically healthy patients in different age groups. The patients were divided randomly into 3 groups (I, II, III) of 10 patients each to be administered with sterile water, non tempered chlorhexidine and tempered chlorhexidine, respectively, as a pre-procedural rinse. The aerosol produced by the ultrasonic unit was collected at 3° clock, 6° clock and 12° clock positions on blood agar plates within a range of 4 feet in all the three groups. The blood agar plates were incubated for 48 hours and the total number of colony forming units (CFUs) were counted and statistically analyzed.
The results showed that CFU in group III and group II were significantly reduced when compared to group I with F=1084.92, P<0.001 (ANOVA). Also, CFU in group III was significantly reduced when compared to group II with P<0.001.
Pre-procedural rinse can significantly reduce the viable microbial content of dental aerosols and tempered chlorhexidine was more effective than non-tempered chlorhexidine.
Aerosol production; colony forming unit; pre-procedural rinse; tempered chlorhexidine
OBJECTIVE--To evaluate early neuropathy in dental personnel exposed to high frequency vibrations. METHODS--30 dentists and 30 dental hygienists who used low and high speed hand pieces and ultrasonic scalers were studied, and 30 dental assistants and 30 medical nurses not exposed to vibration (all women). Vibrotactile sensibility, strength, motor performance, sensorineural symptoms and signs, and vascular symptoms in the hands, as well as mercury concentrations in biological samples and cervicobrachial symptoms, were studied. RESULTS--The two groups exposed to vibration had significant impairments of vibrotactile sensibility, strength, and motor performance, as well as more frequent sensorineural symptoms. In the dentists there were significant associations between the vibrotactile sensibility and strength, motor performance, superficial sensibility, and sensorineural symptoms. There were no associations between these findings and cervicobrachial symptoms, mercury concentrations, or smoking. There was no increase of vascular symptoms of the hands in the groups exposed to vibration. CONCLUSION--Dental hygienists and dentists had a slight neuropathy, which may be associated with their exposure to high frequency vibrations, and which may be detrimental to their work performance. Thus, development of safer equipment is urgent.
Concern about the epidemic of the acquired immune deficiency syndrome led to discussions in one health district about the dangers of cross-infection from instruments in general practice and health authority clinics. In order to establish what current disinfection practices were in use a telephone survey was adopted as a quick and easy method of data collection. Information was collected on who was responsible for disinfection as well as details of how each instrument was disinfected. Results from 69 general practices and 21 health authority clinice in one health district are reported.
Some form of sterilizer was used in 63 general practices. These included water boilers (49%), dry heat sterilizers (41%), autoclaves (5%) and pressure cookers (5%). Sixty one practices were using metal vaginal specula and of these 29 were disinfecting by boiling, three were using pressure cookers, 18 dry heat, seven chemical methods, three autoclaves and one the central sterile department of the local hospital. Of those who were boiling after simple washing, three practices boiled for five to 10 minutes and reused instruments during the same clinic. Of the 29 using simple boiling 20 (69%) were boiling for less than 20 minutes.
The study highlights the fact that no formal advice has been given on disinfection practice by the DHSS, the health authorities or the family practitioner committees. The need to set up local guidelines and develop practical steps for their introduction are discussed.
This study assessed the levels of two key pathogens, Salmonella and Campylobacter, along with the indicator organism Escherichia coli in aerosols within and outside poultry sheds. The study ranged over a 3-year period on four poultry farms and consisted of six trials across the boiler production cycle of around 55 days. Weekly testing of litter and aerosols was carried out through the cycle. A key point that emerged is that the levels of airborne bacteria are linked to the levels of these bacteria in litter. This hypothesis was demonstrated by E. coli. The typical levels of E. coli in litter were ∼108 CFU g−1 and, as a consequence, were in the range of 102 to 104 CFU m−3 in aerosols, both inside and outside the shed. The external levels were always lower than the internal levels. Salmonella was only present intermittently in litter and at lower levels (103 to 105 most probable number [MPN] g−1) and consequently present only intermittently and at low levels in air inside (range of 0.65 to 4.4 MPN m−3) and once outside (2.3 MPN m−3). The Salmonella serovars isolated in litter were generally also isolated from aerosols and dust, with the Salmonella serovars Chester and Sofia being the dominant serovars across these interfaces. Campylobacter was detected late in the production cycle, in litter at levels of around 107 MPN g−1. Campylobacter was detected only once inside the shed and then at low levels of 2.2 MPN m−3. Thus, the public health risk from these organisms in poultry environments via the aerosol pathway is minimal.
Boiling is the most common means of treating water in the home and the benchmark against which alternative point-of-use water treatment options must be compared. In a 5-week study in rural Guatemala among 45 households who claimed they always or almost always boiled their drinking water, boiling was associated with a 86.2% reduction in geometric mean thermotolerant coliforms (TTC) (N = 206, P < 0.0001). Despite consistent levels of fecal contamination in source water, 71.2% of stored water samples from self-reported boilers met the World Health Organization guidelines for safe drinking water (0 TTC/100 mL), and 10.7% fell within the commonly accepted low-risk category of (1–10 TTC/100 mL). As actually practiced in the study community, boiling significantly improved the microbiological quality of drinking water, though boiled and stored drinking water is not always free of fecal contaminations.
To improve fault detection reliability, sensor location should be designed according to an optimization criterion with constraints imposed by issues of detectability and identifiability. Reliability requires the minimization of undetectability and false alarm probability due to random factors on sensor readings, which is not only related with sensor readings but also affected by fault propagation. This paper introduces the reliability criteria expression based on the missed/false alarm probability of each sensor and system topology or connectivity derived from the directed graph. The algorithm for the optimization problem is presented as a heuristic procedure. Finally, a boiler system is illustrated using the proposed method.
fault detection; directed graph; reliability; false alarm; missed alarm
Particulate Matter (PM10) has been one of the main air pollutants exceeding the ambient standards in most of the major cities in India. During last few years, receptor models such as Chemical Mass Balance, Positive Matrix Factorization (PMF), PCA–APCS and UNMIX have been used to provide solutions to the source identification and contributions which are accepted for developing effective and efficient air quality management plans. Each site poses different complexities while resolving PM10 contributions. This paper reports the variability of four sites within Mumbai city using PMF. Industrial area of Mahul showed sources such as residual oil combustion and paved road dust (27%), traffic (20%), coal fired boiler (17%), nitrate (15%). Residential area of Khar showed sources such as residual oil combustion and construction (25%), motor vehicles (23%), marine aerosol and nitrate (19%), paved road dust (18%) compared to construction and natural dust (27%), motor vehicles and smelting work (25%), nitrate (16%) and biomass burning and paved road dust (15%) in Dharavi, a low income slum residential area. The major contributors of PM10 at Colaba were marine aerosol, wood burning and ammonium sulphate (24%), motor vehicles and smelting work (22%), Natural soil (19%), nitrate and oil burning (18%).
The aim of this study was to assess the feasibility of injury specific home safety investigation and to examine the home safety status focused on burn related safety in a rural population in the North-West of Iran.
A cross-sectional study was conducted on 265 rural households of rural Meshkinshahr, Iran. Cluster sampling method was used in 38 clusters with 7 households in each cluster. Clusters were selected on a probability proportional to size (PPS) basis using the available health census database called D-Tarh. Data were analyzed using the statistical software package STATA 8.
Possible risks were explored in fields of house structure; cooking and eating attitudes and behaviors; cooking appliances, specific appliances such as picnic gas burners, valors (traditional heaters), samovars (traditional water boilers), and air-heating appliances. Many safety concerns were explored needing to draw the attention of researchers and public health policy makers.
Injury specific home safety surveys are useful and may provide useful information for safety promotion interventions.
This study makes use of this distinction to analyze the exhaust gas concentration and fuel of the circulating fluidized bed (CFB) boiler that mainly uses wood biomass, and to develop the emission factors of Methane (CH4), Nitrous oxide (N2O). The fuels used as energy sources in the subject working sites are Wood Chip Fuel (WCF), RDF and Refused Plastic Fuel (RPF) of which heating values are 11.9 TJ/Gg, 17.1 TJ/Gg, and 31.2 TJ/Gg, respectively. The average concentrations of CH4 and N2O were measured to be 2.78 ppm and 7.68 ppm, respectively. The analyzed values and data collected from the field survey were used to calculate the emission factor of CH4 and N2O exhausted from the CFB boiler. As a result, the emission factors of CH4 and N2O are 1.4 kg/TJ (0.9–1.9 kg/TJ) and 4.0 kg/TJ (2.9–5.3 kg/TJ) within a 95% confidence interval. Biomass combined with the combustion technology for the CFB boiler proved to be more effective in reducing the N2O emission, compared to the emission factor of the CFB boiler using fossil fuel.
The marine intertidal zone is characterized by large variation in temperature, pH, dissolved oxygen and the supply of nutrients and food on seasonal and daily time scales. These oceanic fluctuations drive of ecological processes such as recruitment, competition and consumer-prey interactions largely via physiological mehcanisms. Thus, to understand coastal ecosystem dynamics and responses to climate change, it is crucial to understand these mechanisms.
Here we utilize transcriptome analysis of the physiological response of the mussel Mytilus californianus at different spatial scales to gain insight into these mechanisms. We used mussels inhabiting different vertical locations within Strawberry Hill on Cape Perpetua, OR and Boiler Bay on Cape Foulweather, OR to study inter- and intra-site variation of gene expression.
The results highlight two distinct gene expression signatures related to the cycling of metabolic activity and perturbations to cellular homeostasis. Intermediate spatial scales show a strong influence of oceanographic differences in food and stress environments between sites separated by ~65 km.
Together, these new insights into environmental control of gene expression may allow understanding of important physiological drivers within and across populations.
ecological genomics; Mytilus californianus; DNA microarray; spatial variation; gene expression; environmental stress; biogeographic distribution; microarray; mussels; stress