Noise pollution in urban environments: a study in Yazd city, Iran

One of the most important sources of noise pollution in urban areas is traffic noise. The aim of the present study was to determine noise pollution in the different parts of Yazd city in 2010 and to compare them with current standard levels.In total, 135 samples were obtained from both residential and commercial areas according to the ISO 1996-2002 method in order to measure noise pressure levels. Locations included 10 streets and 5 squares of the city and the measurement times were considered in the morning, afternoon, and the evening. Noise level was determined in A-weighted by sound level meter model 2232. Results showed that the rate of background noise in Yazd city was high, as it was 71.2±4.4, 66.2±3.7, and 60.3±4 in the L10, L50, and L90, respectively. The mean level of maximum noise pressure was 74.3 dB(A)(Lmax), and the mean continuous sound equivalent level was 66.7 dB(A) (Leq). Comparing the noise level obtained in the present study to the standard level, it can be obviously concluded that the noise levels are higher than that of acceptable levels in most parts of the city. So, different preventive countermeasures such as increasing public awareness through educational programs and technical controls for the future development of the city are crucial

Application of a hazard and operability study method to hazard evaluation of a chemical unit of the power station.

BACKGROUND: The aim of this study was to identify the hazards, evaluate their risk factors and determine the measure for promotion of the process and reduction of accidents in the chemical unit of the power station. METHODS: In this case and qualitative study, HAZOP technique was used to recognize the hazards and problems of operations on the chemical section at power station. Totally, 126 deviations were documented with various causes and consequences. RESULTS: Ranking and evaluation of identified risks indicate that the majority of deviations were categorized as "acceptable" and less than half of that were "unacceptable". The highest calculated risk level (1B) related to both the interruption of acid entry to the discharge pumps and an increased density of the acid. About 27% of the deviations had the lowest risk level (4B). CONCLUSION: The identification of hazards by HAZOP indicates that it could, systemically, assess and criticize the process of consumption or production of acid and alkali in the chemical unit of power plant

Probable contribution of fling-step effect on the response spectra at near source site

Fling-step effect (static offset) besides forward directivity is one the major consequence of near-fault earthquakes. This effect may impose unanticipated seismic demands on structures. Comparing to forward directivity effect, few researches are concerned with the effect of fling-step. In this study, the contribution of fling-step effect on the elastic response spectra was examined by means of a probabilistic method as a new approach in investigation of fling-step effect. To this end, seismological parameters of a significant near-fault earthquake were obtained using inversion solution and MO-GA technique and then by randomly changing hypocenter of causative fault many ground motions were synthesized. Eventually, the influence and also the probable contribution of fling-step on the response spectra were achieved via probabilistic process

Utjecaj izloženosti 1,6-heksametilen diizocijanatu (HDI) na vršni ekspiratorni protok u autolakirera u Iranu

The aim of this study was to investigate the effects of occupational exposure to 1,6-hexamethylene diisocyanate (HDI) on peak flowmetry in automobile body paint shop workers in Iran. We studied a population of 43 car painters exposed to HDI at their workplaces. Peak expiratory fl ow was tested for one working week, from the start to the end of each shift. Air was sampled and HDI analysed in parallel, according to the OSHA 42 method. Daily and weekly HDI exposure averages were (0.42±0.1) mg m-3 and (0.13±0.05) mg m-3, respectively. On painting days, 72 % of workers showed more than a 10 % variation in peak expiratory fl ow. Inhalation exposure exceeded the threshold limit value (TLV) ten times over. This strongly suggests that HDI affected the peak fl owmetry in the studied workers.Cilj je ovog ispitivanja bio utvrditi vršni protok u 43 iranska autolakirera profesionalno izložena 1,6-heksametilen diizocijanatu (HDI). Vršni ekspiratorni protok testiran je tjedan dana na početku i kraju svake smjene. Uzorkovanje i mjerenje HDI-ja u zraku radilo se istodobno s testiranjem vršnoga protoka, prema metodi OSHA 42. Prosječna dnevna izloženost radnika HDI-ju iznosila je (0.42±0.1) mg m-3, a tjedna (0.13±0.05) mg m-3. U 72 % radnika vršni ekspiratorni protok tijekom dana varirao je više od 10 %. Radnici su udisali deset puta više razine HDI-ja od graničnih te je moguće da je HDI utjecao na mjerenja plućne funkcije

Slip-Flow and Heat Transfer of a Non-Newtonian Nanofluid in a Microtube

The slip-flow and heat transfer of a non-Newtonian nanofluid in a microtube is theoretically studied. The power-law rheology is adopted to describe the non-Newtonian characteristics of the flow, in which the fluid consistency coefficient and the flow behavior index depend on the nanoparticle volume fraction. The velocity profile, volumetric flow rate and local Nusselt number are calculated for different values of nanoparticle volume fraction and slip length. The results show that the influence of nanoparticle volume fraction on the flow of the nanofluid depends on the pressure gradient, which is quite different from that of the Newtonian nanofluid. Increase of the nanoparticle volume fraction has the effect to impede the flow at a small pressure gradient, but it changes to facilitate the flow when the pressure gradient is large enough. This remarkable phenomenon is observed when the tube radius shrinks to micrometer scale. On the other hand, we find that increase of the slip length always results in larger flow rate of the nanofluid. Furthermore, the heat transfer rate of the nanofluid in the microtube can be enhanced due to the non-Newtonian rheology and slip boundary effects. The thermally fully developed heat transfer rate under constant wall temperature and constant heat flux boundary conditions is also compared

Immune activation in irritable bowel syndrome: can neuroimmune interactions explain symptoms?

Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal (GI) tract characterized by pain or discomfort from the lower abdominal region, which is associated with altered bowel habit. Despite its prevalence, there is currently a lack of effective treatment options for patients. IBS has long been considered as a neurological condition resulting from alterations in the brain gut axis, but immunological alterations are increasingly reported in IBS patients, consistent with the hypothesis that there is a chronic, but low-grade, immune activation. Mediators released by immune cells act to either dampen or amplify the activity of GI nerves. Release of a number of these mediators correlates with symptoms of IBS, highlighting the importance of interactions between the immune and the nervous systems. Investigation of the role of microbiota in these interactions is in its early stages, but may provide many answers regarding the mechanisms underlying activation of the immune system in IBS. Identifying what the key changes in the GI immune system are in IBS and how these changes modulate viscerosensory nervous function is essential for the development of novel therapies for the underlying disorder.Patrick A. Hughes, Heddy Zola, Irmeli A. Penttila, L. Ashley Blackshaw, Jane M. Andrews, and Doreen Krumbiege

Ocjena i usporedba respiratornih simptoma i kapaciteta pluća u radnika tvornice keramičkih pločica iz Yazda u Iranu

Tile workers are exposed to dust particles and are susceptible to multiple pulmonary complications. Problems like asthma, chronic obstructive pulmonary symptoms, and silicosis are more common among them. As there are many tile factories in Yazd, we decided to evaluate the respiratory symptoms and lung capacities in these workers and compare them with controls. This study included 176 tile and ceramic factory workers occupationally exposed to dust and 115 unexposed workers as controls. We recorded the respiratory symptoms using the British Medical Research Council questionnaire and measured lung capacities of the two groups. All study subjects were male, and the two groups were comparable in age and smoking. The exposed group had frequent respiratory symptoms and a significant relationship between them and duration of employment. In addition, lung capacities in ceramic workers with symptoms were lower than in workers without the symptoms. Even though the respiratory symptoms were more frequent in the exposed group than in controls, lung capacities of the two groups were similar.Radnici u proizvodnji keramičkih pločica izloženi su česticama prašine te su skloni višestrukim plućnim komplikacijama. U njih je veća učestalost tegoba poput astme i simptoma kronične opstruktivne bolesti pluća te silikoze. Budući da u Yazdu ima mnogo tvornica keramike, odlučili smo upravo u tome gradu ocijeniti respiratorne simptome i izmjeriti kapacitet pluća njihovih radnika i usporediti ih s kontrolnom skupinom. Ispitivanje je stoga obuhvatilo 176 radnika u proizvodnji keramičkih pločica izloženih prašini te 115 neizloženih radnika koji su činili kontrolnu skupinu. Respiratorni su se simptomi ispitali rabeći upitnik Britanskoga savjeta za medicinska istraživanja (British Medical Research Council), a u obje je skupine izmjeren kapacitet pluća. Svi su ispitanici bili muškarci, a skupine su se podudarale po dobi i pušenju. Respiratorni simptomi bili su česti u izloženoj skupini te je u njoj uočena značajna povezanost između respiratornih simptoma i radnoga staža u tvornici. Usto su izloženi radnici s respiratornim simptomima iskazali slabije kapacitete pluća od radnika bez simptoma. Ovi su respiratorni simptomi bili češći u izloženoj skupini negoli u kontrolnoj, ali se njihovi kapaciteti pluća nisu bitno razlikovali