809 resultados para Coating nanomaterial


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The plastron theory was tested in adults of Neochetina eichhorniae Warner, 1970, through the analysis of the structure that coats these insects' integument and also through submersion laboratorial experiments. The tegument processes were recognized in three types: agglutinated scales with large perforations, plumose scales of varied sizes and shapes, and hairs. The experiments were carried out on 264 adult individuals which were kept submerged at different time intervals (n = 11) and in two types of treatment, natural non-aerated water and previously boiled water, with four repetitions for each treatment. The tests showed a maximum mortality after 24 hours of immersion in the previously boiled water treatment. The survival of the adults was negative and significantly correlated with the types of treatment employed and within the different time intervals. The values of oxygen dissolved in water (mg/l) differed significantly within the types of treatment employed. They were positively correlated with the survival of the adults in the two types of treatment, although more markedly in the treatment with previously boiled water. The mortality of adults after 24 hours of submersion in the treatment with previously boiled water may be associated with the physical-chemical conditions of the non-tested water in this study, such as low surface tension and concentration of solutes. These results suggest plastron functionality in the adults of this species.

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Nitrogen removal in soybean grains at harvest may exceed biological N2 fixation, particularly if grain yields are as high as typically achieved on "Terra Rossa" soils of Eastern Paraguay. Applying N fertilizer or coating seeds with rhizobial inoculants that enhance nodulation may represent a way of balancing the N budget. However, the effects of such treatments appear to be highly site-specific. The objective of this study was to examine the effects of N application (N) and rhizobial inoculation (I) on nodulation, N accumulation and soybean yields in Eastern Paraguay. Field experiments were conducted in two consecutive soybean seasons. Dry conditions in the first year delayed sowing and reduced plant number m-2 and pod number plant-1. Grain yields were generally below 2 t ha-1 but the +N+I treatment increased yields by about 75%. In the second year favorable conditions resulted in yields of around 4 t ha-1 and the treatments had no effect. Nitrogen accumulation was higher in the first year and could therefore not explain the observed yield differences between years and treatment combinations. The positive effect of the +N+I treatment in year one was associated with a more rapid root growth which could have reduced susceptibility to intermittent drought stress. Nodule biomass decreased between flowering and pod setting stages in the +I treatment whereas further increases in nodule biomass in the -I treatment may have led to competition for assimilates between nodules and developing pods. Based on these preliminary results we conclude that N application and seed inoculation can offer short-term benefits in unfavorable years without negative effects on yield in favorable years.

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A computer-aided method to improve the thickness uniformity attainable when coating multiple substrates inside a thermal evaporation physical vapor deposition unit is presented. The study is developed for the classical spherical (dome-shaped) calotte and also for a plane sector reversible holder setup. This second arrangement is very useful for coating both sides of the substrate, such as antireflection multilayers on lenses. The design of static correcting shutters for both kinds of configurations is also discussed. Some results of using the method are presented as an illustration.

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OBJECTIVE: Few epidemiological studies have addressed the health of workers exposed to novel manufactured nanomaterials. The small current workforce will necessitate pooling international cohorts. METHOD: A road map was defined for a globally harmonized framework for the careful choice of materials, exposure characterization, identification of study populations, definition of health endpoints, evaluation of appropriateness of study designs, data collection and analysis, and interpretation of the results. RESULTS: We propose a road map to reach global consensus on these issues. The proposed strategy should ensure that the costs of action are not disproportionate to the potential benefits and that the approach is pragmatic and practical. CONCLUSIONS: We should aim to go beyond the collection of health complaints, illness statistics, or even counts of deaths; the manifestation of such clear endpoints would indicate a failure of preventive measures.

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The aim of this paper is to describe the process and challenges in building exposure scenarios for engineered nanomaterials (ENM), using an exposure scenario format similar to that used for the European Chemicals regulation (REACH). Over 60 exposure scenarios were developed based on information from publicly available sources (literature, books, and reports), publicly available exposure estimation models, occupational sampling campaign data from partnering institutions, and industrial partners regarding their own facilities. The primary focus was on carbon-based nanomaterials, nano-silver (nano-Ag) and nano-titanium dioxide (nano-TiO2), and included occupational and consumer uses of these materials with consideration of the associated environmental release. The process of building exposure scenarios illustrated the availability and limitations of existing information and exposure assessment tools for characterizing exposure to ENM, particularly as it relates to risk assessment. This article describes the gaps in the information reviewed, recommends future areas of ENM exposure research, and proposes types of information that should, at a minimum, be included when reporting the results of such research, so that the information is useful in a wider context.

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Cities and counties in Iowa have more than 8,890 steel bridges, most of which are painted with red lead paint. The Iowa Department of Transportation (Iowa DOT) maintains less than 35 bridges coated with red lead paint, including seven of the large border bridges over the Mississippi and Missouri Rivers. Because of the federal and state regulations for bridge painting, many governmental agencies have opted not to repaint, or otherwise maintain, lead paint coatings. Consequently, the paint condition on many of these bridges is poor, and some bridges are experiencing severe rusting of structural members. This research project was developed with two objectives: 1) to evaluate the effectiveness of preparing the structural steel surface of a bridge with high pressure water jetting instead of abrasive blasting and 2) to coat the structural steel surface with a moisture-cured polyurethane paint under different surface preparation conditions.

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Tämän diplomityön tavoitteena oli selvittää entsyymikonvertoinnin mahdollisuudet vaikuttaa sideainetärkkelyksen toiminnallisiin ominaisuuksiin. Tärkein tehtävä oli etsiä vastaukset kysymykseen, kuinka paljon entsyymikonvertointia optimoimalla voidaan maksimoida tärkkelyksen positiivisia vaikutuksia. Tavoitteena oli myös tutkia, voiko lisäaineita käyttämällä ja tärkkelystä plastisoimalla säilyttää tärkkelyksen vaikutus paperin jäykkyyteen ja saada tärkkelysfilmille joustavuutta. Kirjallisuusosassa tarkasteltiin tärkkelyksen entsyymikonvertointiin vaikuttavia tekijöitä, eri tärkkelysraaka-aineiden eroja, sekä konvertoinnissa käytettävien entsyymien ominaisuuksia. Kirjallisuusosassa tarkasteltiin myöstärkkelyksen käyttöä sideaineena pigmenttipäällystyksessä. Kokeellisessa osassakeskityttiin selvittämään entsyymikonvertoinnin olosuhteiden, käytettävän raakatärkkelyksen ja entsyymin vaikutusta konvertoidun tärkkelyksen ominaisuuksiin. Konvertoiduista tärkkelyksistä valmistettiin päällystyspastat, ja tutkittiin niinpastan kuin päällystetyn paperin ominaisuuksia. Myös erilaisten pehmentimien vaikutusta niin päällystyspastaan, kuin paperin pinnalle tutkittiin. Havaittiin, että konvertoimalla tärkkelysketjua entsymaattisesti, voidaan tärkkelysketjun pituutta säädellä. Tarkoituksena oli konvertoida tärkkelystä niin, että tärkkelyksen molekyyliketjujakaumat sisältävät lyhyitä, keskipitkiä sekäpitkiä molekyylejä. Päällystämisen havaittiin olevan vaikeaa Helicoaterilla varsinkin pitkäketjuista tärkkelystä suuren määrän sisältävillä pastoilla. Myös tärkkelys/lateksi-suhde vaihteli eri pastoilla. Päällystyspastojen reologisia ominaisuuksia testattaessa huomattiin, että tärkkelysketjun pituuden kasvaessa pastanviskositeetti lisääntyy ja vesiretentio vähenee. Havaittiin vain muutamia teknisiä paperiominaisuuksia, jotka korreloivat hyvin tärkkelysketjun pituuden kanssa. Näitä olivat kiilto, Gurley-Hill huokoisuus, taivutusvastus, taivutuspituus sekä IGT pintalujuus. Pehmentimien ei havaittu vaikuttavan moneenkaan paperin eri tekniseen ominaisuuteen. Suurimmat erot huomattiin paperin taivutuspituudessa ja taivutusvastuksessa.

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The objective of this work was to introduce the emerging non-contacting spray coating process and compare it to the existing coating techniques. Particular emphasis was given to the details of the spraying process of paper coating colour and the base paper requirements set by the new coating method. Spraying technology itself is nothing new, but the atomisation process of paper coating colour is quite unknown to the paper industry. The differences between the rheology of painting and coating colours make it very difficult to utilise the existing information from spray painting research. Based on the trials, some basic conclusion can be made:The results of this study suggest that the Brookfield viscosity of spray coating colour should be as low as possible, presently a 50 mPas level is regarded as an optimum. For the paper quality and coater runnability, the solids level should be as high as possible. However, the graininess of coated paper surface and the nozzle wear limits the maximum solids level to 60 % at the moment. Most likelydue to the low solids and low viscosity of the coating colour the low shear Brookfield viscosity correlates very well with the paper and spray fan qualities. High shear viscosity is also important, but yet less significant than the low shear viscosity. Droplet size should be minimized and besides keeping the brrokfield viscosity low that can be helped by using a surfactant or dispersing agent in the coating colour formula. Increasing the spraying pressure in the nozzle can also reduce the droplet size. The small droplet size also improves the coating coverage, since there is hardly any levelling taking place after the impact with the base paper. Because of the lack of shear forces after the application, the pigment particles do not orientate along the paper surface. Therefore the study indicates that based on the present know-how, no quality improvements can be obtained by the use of platy type of pigments. The other disadvantage of them is the rapid deterioration of the nozzle lifetime. Further research in both coating colour rheology and nozzle design may change this in the future, but so far only round shape pigments, like typically calcium carbonate is, can be used with spray coating. The low water retention characteristics of spray coating, enhanced by the low solids and low viscosity, challenge the base paper absorption properties.Filler level has to be low not to increase the number of small pores, which have a great influence on the absorption properties of the base paper. Hydrophobic sizing reduces this absorption and prevents binder migration efficiently. High surface roughness and especially poor formation of the base paper deteriorate thespray coated paper properties. However, pre-calendering of the base paper does not contribute anything to the finished paper quality, at least at the coating colour solids level below 60 %. When targeting a standard offset LWC grade, spraycoating produces similar quality to film coating, but yet blade coating being on a slightly better level. However, because of the savings in both investment and production costs, spray coating may have an excellent future ahead. The porousnature of the spray coated surface offers an optimum substrate for the coldset printing industry to utilise the potential of high quality papers in their business.

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Therapeutic nanoparticles (NPs) are used in nanomedicine as drug carriers or imaging agents, providing increased selectivity/specificity for diseased tissues. The first NPs in nanomedicine were developed for increasing the efficacy of known drugs displaying dose-limiting toxicity and poor bioavailability and for enhancing disease detection. Nanotechnologies have gained much interest owing to their huge potential for applications in industry and medicine. It is necessary to ensure and control the biocompatibility of the components of therapeutic NPs to guarantee that intrinsic toxicity does not overtake the benefits. In addition to monitoring their toxicity in vitro, in vivo and in silico, it is also necessary to understand their distribution in the human body, their biodegradation and excretion routes and dispersion in the environment. Therefore, a deep understanding of their interactions with living tissues and of their possible effects in the human (and animal) body is required for the safe use of nanoparticulate formulations. Obtaining this information was the main aim of the NanoTEST project, and the goals of the reports collected together in this special issue are to summarise the observations and results obtained by the participating research teams and to provide methodological tools for evaluating the biological impact of NPs.

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Pigmenttipäällystyksen tarkoituksena on parantaa painopapereiden pintaominaisuuksia. Tämän työn tarkoituksena oli löytää sopiva päällystyspasta päällystetylle coldset-paperille. Kirjallisuusosassa on käsitelty coldset-painatusta ja sen ongelmia. Päällystysmenetelmän perusteita, pastan ominaisuuksia ja niiden vaikutusta päällystystulokseen on myös käsitelty. Lisäksi on esitelty joitakin päällystetyn paperin pinnantutkimusmenetelmiä. Kokeellisessa osassa on tutkittu erilaisten pastakoostumusten ja päällystemäärien sekä kalanteroinnin vaikutusta paperin painettavuuteen. Paperit on päällystetty Helicoaterilla ja joitakin pastoja on testattu myös pilot-mittakaavaisessa päällystyksessä. Selitystä paperin käyttäytymiseen painatuksessa on etsitty päällystetyn paperin pintarakenteesta. Paras painettavuus saavutetaan päällysteellä, jossa pigmenttinä on vain karbonaatti. Painojälkeä voidaan parantaa käyttämällä kalsinoitua kaoliinia yhdessä karbonaatin kanssa, mutta tämän päällysteen pintalujuus ei ole riittävä CSWO-painatukseen. Tärkkipigmentti parantaa veden ja painovärin absorptiota ja siten tekee painetun tuotteen kuivemmaksi ja miellyttävämmän tuntuiseksi, mutta aiheuttaa smearingia. Tämä johtuu liian nopeasta musteen asettuvuudesta. "Pehmeä" SB-lateksi soveltuu paremmin offset-painatukseen kuin "kova" lateksi, joka sisältää myös PVAc:ta. "Pehmeällä" lateksilla saadaan parempi pintalujuus ja painojälki kuin "kovalla" lateksilla. Paperin pölyävyyttä painatuksessa voidaan vähentää nostamalla päällystemäärää ja laskemalla pastan kuiva-ainepitoisuutta. Kalanteroinnilla ei pintalujuutta tai painojälkeä voida parantaa. Selitys tutkimuksessa käsiteltyjen papereiden painojäljelle ja painettavuudelle löydetään tutkimalla päällysteen pintarakennetta. Painojälkeen vaikuttaa eniten päällysteen peittoaste. Huonoa peittävyyttä voidaan parantaa nostamalla päällystemäärää. Pölyäminen painatuksessa johtuu pigmenteistä, jotka eivät ole sidottuja paperin pintaan. Tämä taas johtuu pastan huonosta vesiretentiosta. Hyödyllisintä tietoa näiden papereiden pintarakenteesta saadaan tutkimalla pintaa pyyhkäisyelektonimikroskoopilla (SEM), atomivoimamikroskoopilla (AFM) ja laserindusoidulla plasmaspektrometrilla (LIPS). LIPSin etuna on se, että päällystemääräjaukauma voidaan määrittää sekä x-y- että z-suunnassa samanaikaisesti samasta kohdasta. LIPSissä myös näytteen preparointitarve on hyvin vähäinen.

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In traffic accidents involving motorcycles, paint traces can be transferred from the rider's helmet or smeared onto its surface. These traces are usually in the form of chips or smears and are frequently collected for comparison purposes. This research investigates the physical and chemical characteristics of the coatings found on motorcycles helmets. An evaluation of the similarities between helmet and automotive coating systems was also performed.Twenty-seven helmet coatings from 15 different brands and 22 models were considered. One sample per helmet was collected and observed using optical microscopy. FTIR spectroscopy was then used and seven replicate measurements per layer were carried out to study the variability of each coating system (intravariability). Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were also performed on the infrared spectra of the clearcoats and basecoats of the data set. The most common systems were composed of two or three layers, consistently involving a clearcoat and basecoat. The coating systems of helmets with composite shells systematically contained a minimum of three layers. FTIR spectroscopy results showed that acrylic urethane and alkyd urethane were the most frequent binders used for clearcoats and basecoats. A high proportion of the coatings were differentiated (more than 95%) based on microscopic examinations. The chemical and physical characteristics of the coatings allowed the differentiation of all but one pair of helmets of the same brand, model and color. Chemometrics (PCA and HCA) corroborated classification based on visual comparisons of the spectra and allowed the study of the whole data set at once (i.e., all spectra of the same layer). Thus, the intravariability of each helmet and its proximity to the others (intervariability) could be more readily assessed. It was also possible to determine the most discriminative chemical variables based on the study of the PCA loadings. Chemometrics could therefore be used as a complementary decision-making tool when many spectra and replicates have to be taken into account. Similarities between automotive and helmet coating systems were highlighted, in particular with regard to automotive coating systems on plastic substrates (microscopy and FTIR). However, the primer layer of helmet coatings was shown to differ from the automotive primer. If the paint trace contains this layer, the risk of misclassification (i.e., helmet versus vehicle) is reduced. Nevertheless, a paint examiner should pay close attention to these similarities when analyzing paint traces, especially regarding smears or paint chips presenting an incomplete layer system.

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The strength properties of paper coating layer are very important in converting and printing operations. Too great or low strength of the coating can affect several problems in printing. One of the problems caused by the strength of coating is the cracking at the fold. After printing the paper is folded to final form and the pages are stapled together. In folding the paper coating can crack causing aesthetic damage over printed image or in the worst case the centre sheet can fall off in stapling. When folding the paper other side undergoes tensile stresses and the other side compressive stresses. If the difference between these stresses is too high, the coating can crack on the folding. To better predict and prevent cracking at the fold it is good to know the strength properties of coating layer. It has measured earlier the tensile strength of coating layer but not the compressive strength. In this study it was tried to find some way to measure the compressive strength of the coating layer and investigate how different coatings behave in compression. It was used the short span crush test, which is used to measure the in-plane compressive strength of paperboards, to measure the compressive strength of the coating layer. In this method the free span of the specimen is very small which prevent buckling. It was measured the compressive strength of free coating films as well as coated paper. It was also measured the tensile strength and the Bendtsen air permeance of the coating film. The results showed that the shape of pigment has a great effect to the strength of coating. Platy pigment gave much better strength than round or needle-like pigment. On the other hand calcined kaolin, which is also platy but the particles are aggregated, decreased the strength substantially. The difference in the strength can be explained with packing of the particles which is affecting to the porosity and thus to the strength. The platy kaolin packs up much better than others and creates less porous structure. The results also showed that the binder properties have a great effect to the compressive strength of coating layer. The amount of latex and the glass transition temperature, Tg, affect to the strength. As the amount of latex is increasing, the strength of coating is increasing also. Larger amount of latex is binding the pigment particles better together and decreasing the porosity. Compressive strength was increasing when the Tg was increasing because the hard latex gives a stiffer and less elastic film than soft latex.