916 resultados para IONS REMOVAL


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Purpose: Aqueous flow through trabeculectomy blebs has been suggested to influence filtration bleb survival. We investigated the relationship between the requirement to increase aqueous flow via adjustable suture removal and surgical outcomes following "safe trabeculectomy" with mitomycin C (MMC). Methods: 62 consecutive eyes of 53 patients underwent fornix based trabeculectomy with adjustable sutures, intraoperative MMC and intensive postoperative steroids. Subconjunctival antimetabolite injections and bleb needlings were administered according to bleb vascularity and IOP trends. Main outcome measures were: success rates (definition: IOP≤21mmHg and 20% IOP reduction); number of antimetabolite injections; bleb needlings; number of of eyes recommencing glaucoma medications and complications. Results: Mean age was 70.4±16.0 years (mean± SD); mean preoperative IOP was 24.5±9.1 mmHg and decreased to 12.3±8.9mmHg postoperatively. Mean number of sutures was 2.6 ± 0.7. Eyes were divided into 2 groups in relation to the number of sutures removed. The number of subconjunctival MMC injections required for those requiring 2 suture removals was significantly greater than those requiring 1 suture removal (p<0.05) The number of needlings and 5FU injections also increased but did not reach significance (p=0.09 and p=0.34 respectively). Least-squared linear regression analysis showed the number of needlings required had a statistically significant (p=0.05) trend with respect to time elapsed between surgery and first suture removal. No other interventions had significant trends. Mean time between surgery and suture removal was: 4.2±9.2 weeks (suture #1) and 5.7±9.7 weeks (suture#2). Antiglaucoma medication was restarted in only 5 eyes. Postoperative complications were infrequent: Seidel (3.2%), peripheral choroidal effusions at any time (3.2%), and shallow anterior chamber (1.6%). Conclusion: Eyes requiring a greater number of suture removals required a significantly greater number of antifibrosis interventions. The time elapsed before suture removal was inversely related to the number of postoperative needlings, suggesting these eyes may have decreased aqueous production and therefore require aggressive post-operative management to prevent bleb failure.

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Remote monitoring through the use of cameras is widely utilized for traffic operation, but has not been utilized widely for roadway maintenance operations. The Utah Department of Transportation (UDOT) has implemented a new remote monitoring system, referred to as a Cloud-enabled Remote Video Streaming (CRVS) camera system for snow removal-related maintenance operations in the winter. The purpose of this study was to evaluate the effectiveness of the use of the CRVS camera system in snow removal-related maintenance operations. This study was conducted in two parts: opinion surveys of maintenance station supervisors and an analysis on snow removal-related maintenance costs. The responses to the opinion surveys mostly displayed positive reviews of the use of the CRVS cameras. On a scale of 1 (least effective) to 5 (most effective), the average overall effectiveness given by the station supervisors was 4.3. An expedition trip for this study was defined as a trip that was made to just check the roadways if snow-removal was necessary. The average of the responses received from surveys was calculated to be a 33 percent reduction in expedition trips. For the second part of this study, an analysis was performed on the snow removal-related maintenance cost data provided by UDOT to see if the installation of a CRVS camera had an effect in reducing expedition trips. This expedition cost comparison was performed for 10 sets of maintenance stations within Utah. It was difficult to make any definitive inferences from the comparison of expedition costs over the years for which precipitation and expedition cost data were available; hence a statistical analysis was performed using the Mixed Model ANOVA. This analysis resulted in an average of 14 percent higher ratio of expedition costs at maintenance stations with a CRVS camera before the installation of the camera compared to the ratio of expedition costs after the installation of the camera. This difference was not proven to be statistically significant at the 95 percent confident level, but indicated that the installation of CRVS cameras was on the average helpful in reducing expedition costs and may be considered practically significant. It is recommended that more detailed and consistent maintenance cost records be prepared for accurate analysis of cost records for this type of study in the future.

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Pavements constructed in Iowa during the period of the 1920's through the late 1940's were built with an integral curb. The purpose of the curb was to control drainage of water from the pavement surface in areas where runoff took place at a very rapid rate. It is for this reason that curbing is found on pavements constructed during this period. The curbing led the water flowing on the pavement surface to drainage outlets; this helped reduce erosion along the edge of the slab. The curbs have satisfactorily performed the job for which they were intended. The advent of bigger and faster vehicles has created a demand for changes in the design of pavements. Current designs provide wider driving surfaces with reduced grades which can better accommodate the wider cars and trucks. By present day design standards the narrow highways are inadequate and are being replaced or improved. The normal improvement procedure is to widen to 24 feet by providing additional driving surface at each edge of the pavement. Curbing is removed from the pavement so that the surface of the widening can be placed at the same level as that of the slab.

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It is commonly regarded that the overuse of traffic control devices desensitizes drivers and leads to disrespect, especially for low-volume secondary roads with limited enforcement. The maintenance of traffic signs is also a tort liability concern, exacerbated by unnecessary signs. The Federal Highway Administration’s (FHWA) Manual on Uniform Traffic Control Devices (MUTCD) and the Institute of Transportation Engineer’s (ITE) Traffic Control Devices Handbook provide guidance for the implementation of STOP signs based on expected compliance with right-of-way rules, provision of through traffic flow, context (proximity to other controlled intersections), speed, sight distance, and crash history. The approach(es) to stop is left to engineering judgment and is usually dependent on traffic volume or functional class/continuity of system. Although presently being considered by the National Committee on Traffic Control Devices, traffic volume itself is not given as a criterion for implementation in the MUTCD. STOP signs have been installed at many locations for various reasons which no longer (or perhaps never) met engineering needs. If in fact the presence of STOP signs does not increase safety, removal should be considered. To date, however, no guidance exists for the removal of STOP signs at two-way stop-controlled intersections. The scope of this research is ultra-low-volume (< 150 daily entering vehicles) unpaved intersections in rural agricultural areas of Iowa, where each of the 99 counties may have as many as 300 or more STOP sign pairs. Overall safety performance is examined as a function of a county excessive use factor, developed specifically for this study and based on various volume ranges and terrain as a proxy for sight distance. Four conclusions are supported: (1) there is no statistical difference in the safety performance of ultra-low-volume stop-controlled and uncontrolled intersections for all drivers or for younger and older drivers (although interestingly, older drivers are underrepresented at both types of intersections); (2) compliance with stop control (as indicated by crash performance) does not appear to be affected by the use or excessive use of STOP signs, even when adjusted for volume and a sight distance proxy; (3) crash performance does not appear to be improved by the liberal use of stop control; (4) safety performance of uncontrolled intersections appears to decline relative to stop-controlled intersections above about 150 daily entering vehicles. Subject to adequate sight distance, traffic professionals may wish to consider removal of control below this threshold. The report concludes with a section on methods and legal considerations for safe removal of stop control.

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Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration can bring the rapid and long-term suppression of NOB and the onset of the activity of anaerobic ammonium oxidizing bacteria (AnAOB). Real-time quantitative polymerase chain reaction analyses confirmed that such shift in performance was mirrored by a change in population densities, with a very drastic reduction of the NOB Nitrospira and Nitrobacter and a 10-fold increase in AnAOB numbers. The study of biofilm sections with relevant 16S rRNA fluorescent probes revealed strongly stratified biofilm structures fostering aerobic ammonium oxidizing bacteria (AOB) in biofilm areas close to the membrane surface (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal

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Environmental and occupational exposure to heavy metals such as cadmium, mercury and lead results in severe health hazards including prenatal and developmental defects. The deleterious effects of heavy metal ions have hitherto been attributed to their interactions with specific, particularly susceptible native proteins. Here, we report an as yet undescribed mode of heavy metal toxicity. Cd2+, Hg2+ and Pb2+ proved to inhibit very efficiently the spontaneous refolding of chemically denatured proteins by forming high-affinity multidentate complexes with thiol and other functional groups (IC(50) in the nanomolar range). With similar efficacy, the heavy metal ions inhibited the chaperone-assisted refolding of chemically denatured and heat-denatured proteins. Thus, the toxic effects of heavy metal ions may result as well from their interaction with the more readily accessible functional groups of proteins in nascent and other non-native form. The toxic scope of heavy metals seems to be substantially larger than assumed so far.

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The Iowa Department of Public Health (IDPH), Hazardous Waste Site Health Assessment Program was asked by the US Environmental Protection Agency (EPA) to review a round of air sampling data. The air data was collected and analyzed during a removal action at the Le Mars Coal Gas Site in Le Mars, Iowa. EPA asked IDPH to determine from the air data if additional monitoring is necessary throughout the removal action to protect nearby residents from exposure.

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Methylene blue (MB) and light are used for virus inactivation of plasma for transfusion. However, the presence of MB has been the subject of concern, and efforts have been made to efficiently remove the dye after photo-treatment. For this study, plasma was collected by apheresis from 10 donors (group A), then treated using the MacoPharma THERAFLEX procedure (MB; 1 microM, and light exposure; 180 J/cm(2)) (group B), and finally filtered in order to remove the dye (group C). Proteins were analyzed by two-dimensional electrophoresis, and peptides showing modifications were characterized by mass spectrometry. Clottable and antigenic fibrinogen levels, as well as fibrin polymerization time were measured. Analyses of the gels focused on a region corresponding to pI between 4.5 and 6.5, and M(r) from 7000 to 58 000. In this area, 387 +/- 47 spots matched, and four of these spots presented significant modifications. They corresponded to changes of the gamma-chain of fibrinogen, of transthyretin, and of apolipoprotein A-I, respectively. A decrease of clottable fibrinogen and a prolongation of fibrin polymerization time were observed in groups B and C. Removal of MB by filtration was not responsible for additional protein alterations. The effect of over-treatment of plasma by very high concentrations of MB (50 microM) in association with prolonged light exposure (3 h) was also analyzed, and showed complex alterations of most of the plasma proteins, including fibrinogen gamma-chain, transthyretin, and apolipoprotein A-I. Our data indicates that MB treatment at high concentration and prolonged illumination severely injure plasma proteins. By contrast, at the MB concentration used to inactivate viruses, damages are apparently very restricted.

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Metallic foreign bodies are rarely found in the maxillary sinus, and usually they have a dental origin.Potential complications related to foreign bodies include recurrent sinusitis, rhinolith formation, cutaneous fistula,chemical poisoning, facial neuralgic pain and even malignancies.Two main surgical approaches are currently used for the removal of foreign bodies in the maxillary sinus: the bone flap and the endoscopic sinus techniques. We are reporting two unusual cases of large high-velocity foreign bodies removed by a modified maxillary lateral antrotomy,with free bone flap repositioning and fixation with a titanium miniplate.

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Nanotiltration is a membrane separation method known for its special characteristic of rejecting multivalent ions and passing monovalent ions. Thus, it is commonly applied with dilute aqueous solutions in partial salt removal, like in drinking water production. The possibilities of nanofiltration have been studied and the technique applied in a wide branch of industries, e.g. the pulp and paper, the textile and the chemical processing industry. However, most present applications and most of the potential applications studied involve dilute solutions, the permeating stream being generally water containing monovalent salts. In this study nanotiltration is investigated more as a fractionation method. A well-known application in the dairy industry is concentration and partial salt removal from whey. Concentration and partial demineralization is beneficial for futher processing of whey as whey concentrates are used e.g. in baby foods. In the experiments of this study nanotiltration effectively reduced the monovalent salts in the whey concentrate. The main concern in this application is lactose leakage into the permeate. With the nanofiltration membranes used the lactose retentions were practically ? 99%. Another dairy application studied was the purification and reuse of cleaning solutions. This is an environmentally driven application. An 80% COD reduction by nanofiltration was observed for alkaline cleaning-in-place solution. Nanofiltration is not as commonly applied in the sugar and sweeteners industry as in the dairy industry. In this study one potential application was investigated, namely xylose purification from hemicellulose hydrolyzate. Xylose is raw material for xylitol production. Xylose separation from glucose was initially studied with xylose-glucose model solutions. The ability of nanofiltration to partially separate xylose into the permeate from rather concentrated xylose-glucose solutions (10 w-% and 30 w-%) became evident. The difference in size between xylose and glucose molecules according to any size measure is small, e.g. the Stokes diameter of glucose is 0.73 nm compared to 0.65 nm for xylose. In further experiments, xylose was purified into nanoliltration permeate from a hemicellulose hydrolyzate solution. The xylose content in the total solids was increased by 1.4—1.7 fold depending on temperature, pressure and feed composition.

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Monissasovelluksissa on hyvin tärkeää vähentää valolähteen vaikutusta kohteen oikean värin havainnoimiseksi. Tämä on tarpeen mm. virtuaalisissa museoissa, telelääketieteessä, verkkokaupassa ja verkkorahassa. Tässä tutkielmassa on kehitetty tekniikkaa kirkkaiden heijastusten poistoon spektrikuvista. Työ sisältää katsauksen yleisen värillisen kuvan ymmärtämiseen, mihin perustuen analysoitiin erilaisia kirkkaiden heijastusten poistO'tekniikoita. Työssä kehitettiin uusi kirkkaiden heijastusten poistO'menetelmä, joka perustuu dikromaattiseen heijastus-malliin, joka kuvaa spektrisen datan objektin omaan väriin ja valaisevan valon väriin perustuen. Ehdotettu kirkkaiden heijastusten poistO'menetelmä hyödyntää erilaisia olemassaolevia menetelmiä, kuten pääkomponenttimenetelmää ja tiedon luokittelu-menetelmää. Yritys kehittää nopeasti toimiva algoritmi, joka myös suoriutuu tehtävästä hyvin, on onnistunut. Kokeet toteutettiin ehdotetun menetelmän mukaisesti ja toimivalla algoritmilla saatiin halutut lopputulokset. Edelleentyö sisältää ehdotuksia esitetyn algoritmin parantamiseksi.

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Diplomityön tarkoituksena oli parantaa Stora Enso Sachsenin siistausprosessissa tuotetun uusiomassan vaaleuden kehitystä ja tutkia siihen vaikuttavia tekijöitä. Työn kirjallisessa osassa käsiteltiin uusiomassan kuidutusta ja vaahdotussiistausprosessia, sekä keräyspaperin ominaisuuksia ja käyttöä paperiteollisuuden raaka-aineena. Kokeellisessa osassa keskityttiin modifioidun natriumsilikaatin annostuksenoptimointiin ja vaikutuksiin laboratorio- ja prosessioloissa, sekä kesäefektin vaikutuksen tutkimiseen kuidutuksessa ja flotaation eri vaiheissa. Natriumsilikaatin laboratoriotutkimuksessa havaittiin, että korkein vaaleus suhteellisesti pienimmällä laboratorioflotaation häviöllä saavutettiin korkeimmalla tutkitulla natriumsilikaatin annostuksella, joka oli 1,1 %. Korkea natriumsilikaattiannostus yhdistettyinä korkeisiin vetyperoksidiannostukseen, 0,5 %, sekä korkeaan kokonaisalkaliteettiin, 0.33 %, johti korkeimpaan massan vaaleuteen ja pienimpiin häviöihin. Laboratoriotutkimuksen pohjalta modifioidulla natriumsilikaatilla suoritettiin koeajoja prosessissa. Noin 1 % natriumsilikaatin annostuksella havaittiin parempi pH:n bufferointikyky, pienempi kalsiumkarbonaatin määrä flotaation primäärivaiheissa, sekä lievästi parempi massan vaaleus verrattuna prosessissa aiemmin käytettyyn standardinatriumsilikaattiin. Kesäefektitutkimuksessa havaittiin, että kesäefektillä on suurin vaikutus esiflotaation primäärivaiheeseen, sillä primäärivaiheessa kuitujen osuus on huomattavasti suurempi kuin sekundäärivaiheissa. Esiflotaation primäärivaiheen uusiomassojen laboratorioflotaatioiden avulla saavutettujen maksimivaaleuksien ero kesän ja talven välillä oli noin 1,5 %ISO. Kesäefektin ei havaittu suuresti vaikuttavan flotaation sekundäärivaiheisiin.

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In this thesis, cleaning of ceramic filter media was studied. Mechanisms of fouling and dissolution of iron compounds, as well as methods for cleaning ceramic membranes fouled by iron deposits were studied in the literature part. Cleaning agents and different methods were closer examined in the experimental part of the thesis. Pyrite is found in the geologic strata. It is oxidized to form ferrous ions Fe(II) and ferric ions Fe(III). Fe(III) is further oxidized in the hydrolysis to form ferric hydroxide. Hematite and goethite, for instance, are naturally occurring iron oxidesand hydroxides. In contact with filter media, they can cause severe fouling, which common cleaning techniques competent enough to remove. Mechanisms for the dissolution of iron oxides include the ligand-promoted pathway and the proton-promoted pathway. The dissolution can also be reductive or non-reductive. The most efficient mechanism is the ligand-promoted reductive mechanism that comprises two stages: the induction period and the autocatalytic dissolution.Reducing agents(such as hydroquinone and hydroxylamine hydrochloride), chelating agents (such as EDTA) and organic acids are used for the removal of iron compounds. Oxalic acid is the most effective known cleaning agent for iron deposits. Since formulations are often more effective than organic acids, reducing agents or chelating agents alone, the citrate¿bicarbonate¿dithionite system among others is well studied in the literature. The cleaning is also enhanced with ultrasound and backpulsing.In the experimental part, oxalic acid and nitric acid were studied alone andin combinations. Also citric acid and ascorbic acid among other chemicals were tested. Soaking experiments, experiments with ultrasound and experiments for alternative methods to apply the cleaning solution on the filter samples were carried out. Permeability and ISO Brightness measurements were performed to examine the influence of the cleaning methods on the samples. Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis of the solutions was carried out to determine the dissolved metals.