1000 resultados para Cleaning section
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The objective of the present study was to investigate factors associated with cesarean sections in two cities located in different regions of Brazil and to determine factors that explain the higher cesarean section rate in the more developed city, Ribeirão Preto, compared to the less developed one, São Luís. Data from two cohort studies comprising 2846 women in Ribeirão Preto in 1994, and 2443 women in São Luís in 1997/1998 were used. Adjusted and non-adjusted risk estimates were calculated using a Poisson regression model. The cesarean section rate was 33.7% in São Luís and 50.8% in Ribeirão Preto. Adjusted analysis in a joint sequential model revealed a 51% higher risk of cesarean section in Ribeirão Preto compared to São Luís (prevalence rate ratio (PRR) = 1.51). Adjustment for category of hospital admission reduced the PRR to 1.09, i.e., this variable explained 82% of the difference in the cesarean section rate between the two cities. Adjustment for the variable "the same physician for prenatal care and delivery" reduced the PRR to 1.07, with the "physician" factor explaining 86% of the difference between rates. When simultaneously adjusted for the two variables, the PRR decreased to 1.05, with these two variables explaining 90% of the difference in the cesarean section rate between the two cities, and the difference was no longer significant. The difference in the cesarean section rate between the two Brazilian cities, one more and one less developed, was mainly explained by the physician factor and, to a lesser extent, by the category of hospital admission.
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Both epidural and general anesthesia can impair thermoregulatory mechanisms during surgery. However, there is lack of information about the effects of different methods of anesthesia on newborn temperature. The purpose of this study was to determine whether there are differences in newborn rectal temperature related to type of anesthesia. Sixty-three pregnant women were randomly assigned to receive general or epidural anesthesia. Maternal core temperature was measured three times with a rectal probe just before anesthesia, at the beginning of surgery and at delivery. In addition, umbilical vein blood was sampled for pH. The rectal temperatures of the babies were recorded immediately after delivery, and Apgar scores were determined 1, 5, and 10 min after birth. The duration of anesthesia and the volume of intravenous fluid given during the procedure (833 ± 144 vs 420 ± 215 mL) were significantly higher in the epidural group than in the general anesthesia group (P < 0.0001). Maternal rectal temperatures were not different in both groups at all measurements. In contrast, newborn rectal temperatures were lower in the epidural anesthesia group than in the general anesthesia group (37.4 ± 0.3 vs 37.6 ± 0.3°C; P < 0.05) immediately after birth. Furthermore, the umbilical vein pH value (7.31 ± 0.05 vs 7.33 ± 0.01; P < 0.05) and Apgar scores at the 1st-min measurement (8.0 ± 0.9 vs 8.5 ± 0.7; P < 0.05) were lower in the epidural anesthesia group than in the general anesthesia group. Since epidural anesthesia requires more iv fluid infusion and a longer time for cesarean section, it involves a risk of a mild temperature reduction for the baby which, however, did not reach the limits of hypothermia.
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Laser beam welding (LBW) is applicable for a wide range of industrial sectors and has a history of fifty years. However, it is considered an unusual method with applications typically limited to welding of thin sheet metal. With a new generation of high power lasers there has been a renewed interest in thick section LBW (also known as keyhole laser welding). There was a growing body of publications during 2001-2011 that indicates an increasing interest in laser welding for many industrial applications, and in last ten years, an increasing number of studies have examined the ways to increase the efficiency of the process. Expanding the thickness range and efficiency of LBW makes the process a possibility for industrial applications dealing with thick metal welding: shipbuilding, offshore structures, pipelines, power plants and other industries. The advantages provided by LBW, such as high process speed, high productivity, and low heat input, may revolutionize these industries and significantly reduce the process costs. The research to date has focused on either increasing the efficiency via optimizing process parameters, or on the process fundamentals, rather than on process and workpiece modifications. The argument of this thesis is that the efficiency of the laser beam process can be increased in a straightforward way in the workshop conditions. Throughout this dissertation, the term “efficiency” is used to refer to welding process efficiency, specifically, an increase in efficiency refers an increase in weld’s penetration depth without increasing laser power level or decreasing welding speed. These methods are: modifications of the workpiece – edge surface roughness and air gap between the joining plates; modification of the ambient conditions – local reduction of the pressure in the welding zone; modification of the welding process – preheating of the welding zone. Approaches to improve the efficiency are analyzed and compared both separately and combined. These experimentally proven methods confirm previous findings and contribute additional evidence which expand the opportunities for laser beam welding applications. The focus of this research was primarily on the effects of edge surface roughness preparation and pre-set air gap between the plates on weld quality and penetration depth. To date, there has been no reliable evidence that such modifications of the workpiece give a positive effect on the welding efficiency. Other methods were tested in combination with the two methods mentioned above. The most promising - combining with reduced pressure method - resulted in at least 100% increase in efficiency. The results of this thesis support the idea that joining those methods in one modified process will provide the modern engineering with a sufficient tool for many novel applications with potential benefits to a range of industries.
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The effectiveness of cleaning and sanitizing procedures in controlling Staphylococcus aureus, Salmonella Enteritidis, and Pseudomonasfluorescens adhered to granite and stainless steel was evaluated. There was no significant difference (p > 0.05) in the adherence of pure cultures of these microorganisms to stainless steel. The numbers of P. fluorescens and S. Enteritidis adhered to granite were greater (p < 0.05) than the numbers of S. aureus. Additionally, the adherence of P. fluorescens was similar to the adherence of S. Enteritidis on granite surface. In a mixed culture with P. fluorescens, S aureus adhered less (p < 0.05) to stainless steel surfaces (1.31 log CFU.cm-2) than when in a pure culture (6.10 log CFU.cm-2). These results suggest that P. fluorescens inhibited the adherence of S. aureus. However, this inhibition was not observed in the adherence process for granite. There was a significant difference (p < 0.05) between the number of adhered cells before and after pre-washing for S. aureus on stainless steel and granite surfaces, and after washing with detergent for all microorganisms and surfaces. The efficiency of the cleaning plus sanitizing procedures was not significantly different (p > 0.05) between the surfaces. However, a significant difference was observed (p < 0.05) between the sanitizer solutions. Sodium hypochlorite and peracetic acid were more bactericidal (p < 0.05) than a quaternary ammonium compound. With regard to microorganisms, S. aureus was the least resistant to the sanitizers. These results show the importance of good cleaning and sanitization procedures to prevent bacterial adherence and biofilm formation.
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Kirjallisuusarvostelu
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Diplomityön tavoitteena on löytää UPM Kymin paperikone 8:n ensimmäisen kuivatusryhmän johtoteloihin kulumis- ja korroosiokestävämpi materiaali ja pinnoite vallitsevaan olosuhteeseen. Teloihin muodostuu pistemäistä korroosiota ja korroosioalue on paikallinen. Korroosiota syntyy kuivatusviiran alueella, jossa ei ole paperirainaa. Työssä suoritetaan kuivatusosan olosuhdemittauksia ja tutkitaan niiden vaikutuksia korroosion muodostumiseen. Suoritettavat olosuhdemittaukset ovat huuvan ilmatase, paineen 0-taso sekä lämpötilat ja kosteudet eri huuvan osissa. Savukaasumittauksen avulla tutkitaan huuvan ilmankiertoa ensimmäisen kuivatusryhmän viiranjohtotelojen läheisyydessä. Kuivatusviiran ilmanläpäisymittauksen avulla saadaan tietoa viiran ilmanläpäisykyvystä. Hypoteesina viiran tukkeutuminen johtuu pölyävästä kuivaus-prosessista ja kosteudesta. SEM/EDS-alkuainemittauksen avulla pystytään analysoimaan korrosiivisia alkuaineita niin korroosioalueella kuin ympäristössä. Työn tutkimuksen perusteella korroosion muodostuminen aiheutuu tukkeutuneen viiran muodostamasta happipitoisuuseroalueesta. Viiran saostumat sisältävät korrosiivisia kemikaaleja, kuten kloridia, rikkiä ja mangaania. Nämä kiihdyttävät korroosiota happipuutosalueella. Huuvan olosuhdemittauksien perusteella huuvan paineen 0-taso on vino. Savukaasu- ja kosteusmittauksien avulla huomattiin kostean ilman jäävän telojen läheisyyteen. Työssä kehitettiin paineilmapuhdistin viiran reuna-alueen puhdistamiseen. Kaavattaviin telapositioihin valittiin kobolttikromiseostettu volframikarbidipinnoite PTFE -fluoripolymeeritiivistyksellä. Muihin telapositioihin valittiin ETFE –fluori-polymeeripinnoite korroosion ehkäisemiseksi. Pinnoitteiden ja paineilmapuhdistimen avulla telojen käyttöaika nousee nykyisestä kahdesta vuodesta tavoiteltuun 10 vuoteen.
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The objective of the work is to study the flow behavior and to support the design of air cleaner by dynamic simulation.In a paper printing industry, it is necessary to monitor the quality of paper when the paper is being produced. During the production, the quality of the paper can be monitored by camera. Therefore, it is necessary to keep the camera lens clean as wood particles may fall from the paper and lie on the camera lens. In this work, the behavior of the air flow and effect of the airflow on the particles at different inlet angles are simulated. Geometries of a different inlet angles of single-channel and double-channel case were constructed using ANSYS CFD Software. All the simulations were performed in ANSYS Fluent. The simulation results of single-channel and double-channel case revealed significant differences in the behavior of the flow and the particle velocity. The main conclusion from this work are in following. 1) For the single channel case the best angle was 0 degree because in that case, the air flow can keep 60% of the particles away from the lens which would otherwise stay on lens. 2) For the double channel case, the best solution was found when the angle of the first inlet was 0 degree and the angle of second inlet was 45 degree . In that case, the airflow can keep 91% of particles away from the lens which would otherwise stay on lens.
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1905 (SESSION29).
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1878.
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1901 (SESSION25).
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1899 (SESSION23).
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1887 (SESSION11).