938 resultados para PLASTICIZED STARCH
Resumo:
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.
Resumo:
Diplomityössä tutkittiin kartonkikoneen retentiojärjestelmää ja eri mahdollisuuksia retention ja vedenpoiston tehostamiseen. Tavoitteena oli parantaa etenkin runkokerroksen retentiota ja vedenpoistoa. Työssä testattiin kilpailevan kemikaalitoimittajan mikropartikkelia kartonkikoneella. Lisäksi runkokerroksessa testattiin retentiotärkkelyksen vaikutus kartongin palstaumislujuuteen, suoritettiin käytössä olevan mikropartikkelin annostuksen optimointi sekä testattiin alunan käyttöä retentioainesysteemin tehoaineena. Kirjallisuusosassa tarkasteltiin pinta- ja kolloidikemian perusteita, retentioainejärjestelmiä ja niissä käytettäviä kemikaaleja sekä retentioaineilla tehtävään flokkaukseen vaikuttavia tekijöitä. Laboratoriokokeilla tutkittiin kokeellisessa osassa eri mikropartikkelijärjestelmien toimivuutta kartonkikoneen eri kerroksien massoilla. Toimivimmaksi osoittautuneella mikropartikkelilla suoritettiin pilot-koeajo runkokerroksen massalla. Lisäksi suoritettiin toinen pilot-koeajo, jossa tutkittiin mikropartikkelin vaikutuksia saostuman aiheuttajana. Pilot-koeajoissa saavutettiin samat retentiotasot kuin referenssisysteemillä lähes puolet pienemmällä kemikaalin kulutuksella. Kartongin laatuominaisuuksista huokoisuus, formaatio ja AKD-liiman retentio muuttuivat viiraretention mukaan. Saostumakoeajossa ei todettu retentioaineen vaikuttavan saostumien syntyyn. Täyden mittakaavan koeajossa tarkoituksena oli testata kilpailevan mikropartikkelin toimivuus kartonkikoneella. Koeajossa etsittiin optimaalinen mikropartikkelin annostus eri kerroksiin. Pintakerroksen tuhkaretentio nousi hiukan ja vedenpoisto parani. Runko- ja taustakerroksessa saavutettiin samat retentiotasot sekä vedenpoistot. Samat retentiotasot saavutettiin n. 25 % pienemmällä mikropartikkelin kulutuksella. Kartongin laatuominaisuuksista seurattiin palstautumislujuutta, formaatiota ja AKD-liiman retentoitumista. Kartongin palstautumislujuus heikkeni. Vastaavasti runko- ja taustakerroksen AKD-liiman retentio oli hiukan korkeampi koeajetulla mikropartikkelilla. Formaatiossa ei tapahtunut merkittäviä muutoksia. Jatkokokeet tehtiin kartonkikoneen runkokerroksessa. Kokeissa todettiin retentiotärkkelyksen vaikuttavan kartongin palstautumislujuuteen. Käytössä olevan mikropartikkelin annostelun optimointikokeissa ei saavutettu parannusta retentioon eikä vedenpoistoon. Mikropartikkelilla saavutetaan tietty retentiotaso, jonka jälkeen sillä ei ole enää vaikutusta retentiotasoon. Alunan annostelukokeissa ei alle yksi kg/t annosmäärällä ole vaikutusta retentioon ja vedenpoistoon.
Resumo:
This study evaluated the chemical composition of peeled and unpeeled green banana Cavendish (AAA) flour obtained by drying in spouted bed, aiming at adding nutritional value to food products. The bananas were sliced and crushed to obtain a paste and fed to the spouted bed dryer (12 cm height and T = 80 ºC) in order to obtain flour. The flours obtained were subjected to analysis of moisture, protein, ash, carbohydrates, total starch, resistant starch, fiber. The green banana flours, mainly unpeeled, are good sources of fiber and resistant starch with an average of 21.91g/100g and 68.02g/100g respectively. The protein content was found in an average of 4.76g/100g, being classified as a low biological value protein with lysine as the first limiting amino acid. The results showed that unpeeled green banana flour obtained by spouted bed drying can be a valuable tool to add nutritional value to products in order to increase their non-digestible fraction.
Resumo:
Työn tavoitteena oli selvittää rainan irrotukseen puristinosan keskitelalta vaikuttavat tärkeimmät tekijät. Työn avulla pyrittiin ymmärtämään tuotantokoneella esiintyvien prosessimuuttujien vaikutusta rainan irrotustapahtumaan ja puristin- ja kuivatusosan väliseen vetoerotarpeeseen. Samalla tutkittiin märkävetojen vaikutusta paperin laatuun ja fluting-käyttäytymiseen HSWO-painossa. Kirjallisuusosassa käsiteltiin märän rainan irrotuksen perusteoriaa sekä rainan ja telapinnan väliseen adheesioon vaikuttavia tekijöitä. Kirjallisuusviitteiden avulla koottiin yhteen tärkeimmät rainan irrotukseen ja keskitelan ajettavuuteen vaikuttavat tekijät. Kirjallisuuden antamien viitteiden perusteella valittiin seurattavat prosessimuuttujat kokeelliseen osaan. Työn kokeellinen osa suoritettiin tuotantokoneella prosessiseurantana. Irrotusta tutkittiin rainan irrotuskohdan muutosten ja puristin- ja kuivatusosan välisen vetoeron avulla. Seurannan perusteella pyrittiin löytämään normaalissa ajotilanteessa rainan irrotusetäisyyteen suurimmat vaihteluita aiheuttavat tekijät. Lisäksi suoritettiin muutamia koeajoja, joiden uskottiin vaikuttavan irrotukseen. Valikoiduista koepisteistä analysoitiin myös vaikutus paperin laatusuureisiin. Työn perusteella selvitettiin suurin osa kyseisellä koneella irrotukseen vaikuttavista muuttujista. Tutkituista viira- ja puristinosan mekaanisista muuttujista eniten irrotukseen vaikuttivat koneen nopeus ja suihkuviirasuhde. Myös viiraosan vedenpoistoelementeillä ja puristinosan höyrylaatikolla havaittiin olevan vaikutusta irrotukseen. Prosessiin lisätyistä raaka-aineista irrotukseen vaikuttivat eniten CTMP:n osuus tuoremassasta, kationinen retentioaine sekä massatärkkelys. Massojen jauhatuksella sekä pohjapaperin täyteainepitoisuudella oli myös selvä vaste irrotukseen. Prosessin kemiallista tilaa kuvaavista suureista irrotukseen vaikutti selvimmin massasysteemin varaustila. Puristin- ja kuivatusosan välisen vetoeron korvaaminen viira- ja puristinosan välisellä vetoerolla helpotti irrotusta keskitelalta, mutta ei tuonut etuja paperin laatuominaisuuksiin eikä vähentänyt fluting-käyttäytymistä.
Resumo:
Flowers of Annonaceae are characterized by fleshy petals, many stamens with hard connective shields and numerous carpels with sessile stigmas often covered by sticky secretions. The petals of many representatives during anthesis form a closed pollination chamber. Protogynous dichogamy with strong scent emissions especially during the pistillate stage is a character of nearly all species. Scent emissions can be enhanced by thermogenesis. The prevailing reproductive system in the family seems to be self-compatibility. The basal genus Anaxagorea besides exhibiting several ancestral morphological characters has also many characters which reappear in other genera. Strong fruit-like scents consisting of fruit-esters and alcohols mainly attract small fruit-beetles (genus Colopterus, Nitidulidae) as pollinators, as well as several other beetles (Curculionidae, Chrysomelidae) and fruit-flies (Drosophilidae), which themselves gnaw on the thick petals or their larvae are petal or ovule predators. The flowers and the thick petals are thus a floral brood substrate for the visitors and the thick petals of Anaxagorea have to be interpreted as an antipredator structure. Another function of the closed thick petals is the production of heat by accumulated starch, which enhances scent emission and provides a warm shelter for the attracted beetles. Insight into floral characters and floral ecology of Anaxagorea, the sister group of the rest of the Annonaceae, is particularly important for understanding functional evolution and diversification of the family as a whole. As beetle pollination (cantharophily) is plesiomorphic in Anaxagorea and in Annonaceae, characters associated with beetle pollination appear imprinted in members of the whole family. Pollination by beetles (cantharophily) is the predominant mode of the majority of species worldwide. Examples are given of diurnal representatives (e.g., Guatteria, Duguetia, Annona) which function on the basis of fruit-imitating flowers attracting mainly fruit-inhabiting nitidulid beetles, as well as nocturnal species (e.g., large-flowered Annona and Duguetia species), which additionally to most of the diurnal species exhibit strong flower warming and provide very thick petal tissues for the voracious dynastid scarab beetles (Dynastinae, Scarabaeidae). Further examples will show that a few Annonaceae have adapted in their pollination also to thrips, flies, cockroaches and even bees. Although this non-beetle pollinated species have adapted in flower structure and scent compounds to their respective insects, they still retain some of the specialized cantharophilous characters of their ancestors.
Resumo:
The response of the common carp to diets with varying amounts of digestible starch, provided either as pea meal (LP, HP, 30 and 46% peas, respectively) or as cereal (LW, HW, 30 and 46% wheat, respectively), was studied and compared with the response to a carbohydrate-free protein-rich diet (CF). Here we focused on the utilisation of dietary carbohydrates by examining the relationship between dietary starch intake, hepatic hexokinase activities, circulating insulin and muscle insulin receptor system. Plasma glucose concentration and hepatic high Km hexokinase (glucokinase, GK) activity were not affected by the content of digestible starch, but 6 h after feeding enzyme activity was higher in the fish fed carbohydrate diets. Similarly, low Km hexokinase (HK) activity was also higher in the fish 24 h after feeding. Fat gain and protein retention were significantly improved by increased digestible starch intake, especially in the HP group, which in turn, presented the highest plasma insulin levels. Glycogen stores were moderately increased by the ingestion of digestible starch. The number of insulin receptors was greater in the CF group than in fish on carbohydrates, except the HP group. Our results confirmed that the common carp uses dietary carbohydrates efficiently, especially when there are provided by peas. This efficiency might be related to the enhanced response of postprandial insulin observed in the HP group.
Resumo:
This study presents an automated system for potentiometric determination of free and total cyanide which employs a homogeneous membrane tubular ion-selective electrode. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A Turbo Pascal® computer program, developed specifically for this task, automatically performs all the steps involved in data acquisition and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a tubular electrode, whose assembly is fast and easy. The system has shown reproducibility (r.s.d. < 0.5%, n=6) and high speed (30 readings/hour); it is efficient for determination of free and total cyanide in waste waters of starch processing plants. The detection limit was 1.2x10-5 and 1.5x10-5 mol L-1, for determination of free and total cyanide, respectively. The linear response range was between 1.2x10-5 and 1.0x10-2 mol L-1 for free cyanide and between 1.5x10-5 and 1.0x10-2 for total cyanide.
Resumo:
Humidity and ash content of powder and bran of algaroba pods are important quality parameters for biological control during storage. The studies of humidity and ash content were carried out conventional and thermogravimetric methods. Different values were obtained by the various methods. The thermogravimetric method was faster and required less sample for the humidity and ash analyses of the powder and bran of algaroba pods. The differential scanning calorimetry curves of the powder and bran of algaroba pods, dryed at 55 ºC, showed two peaks, one corresponding to the gelatinization of starch and the other to the vaporization of water. The samples dryed at 65, 75, 85, 95 and 105 ºC showed one peak, corresponding to the vaporization of water.
Resumo:
A flow injection spectrophotometric procedure was developed for the determination of metamizol in pharmaceutical formulations. The system is based on the reaction between metamizol and triiodide generated in the system by mixing iodate and iodide-starch solutions. The absorbance of triiodide-starch complex giving a steady-state baseline value which was monitored at 580 nm. The inverse peaks caused by metamizol samples were measured and there was a direct relationship between absorbance decreasing and metamizol concentration from 1.4 x 10-4 to 7.0 x 10-4 mol L-1. The RSD was 0.45 % for a metamizol solution 4.2 x 10-4 mol L-1 (n = 10) with a detection limit (three-fold blank standard deviation/slope) of 6.0 x 10-5 mol L-1 The feasibility of the system was demonstrated for the determination of metamizol in commercial samples with sixty results obtained per hour. The results obtained for metamizol in pharmaceutical formulations using the proposed flow procedure and those obtained using an iodimetric procedure are in agreement at the 95% confidence level and within an acceptable range of error.
Resumo:
The process of anaerobic digestion has been greatly developed during the last decades for the treatment of wastewater from food industries as for example, wastewaters from sugar and starch manufacturing and from breweries. However, for wastewaters which contain high amounts of fats and proteins, such as those from slaughterhouses and dairies, anaerobic digestion was found to be troublesome, due to the potential of sludge flotation, the formation of scum layers of lipids at the surface of the reactor, which are not digested and the toxicity of the intermediate compounds (long chain fatty acids) generated during the anaerobic digestion of the wastewater. The addition of hydrolytic enzymes, such as lipases prior to the anaerobic digestion can minimize these problems. In this work, this strategy is reviewed and the technical issues that must be considered in determining its feasibility are discussed.
Resumo:
Microfibrillated cellulose (MFC) is known to enhance strength properties of paper. Improved strength usually means increased bonding which is strongly connected to dimensional instability of paper. Dimensional instability is due to changes in moisture content of paper; when paper is moistened it expands and when dried, it shrinks. Hygroexpansion is linked to end-use problems and excessive drying shrinkage consumes strength potential. Effective use of materials requires controlling of these phenomena. There isn’t yet data concerning dimensional stability of papers containing MFC which restricts wider use of MFC. Main objective of the work was to evaluate dimensional stability of wood-free paper containing different amounts of MFC. Sheets were dried with different methods to see how drying strains effected on drying shrinkage and hygroexpansion. Also tensile strength was measured to find out the effect of MFC. Results were compared to sheets containing kraft fines and in some test points cationic starch was used alongside with MFC. MFC increased the dimensional instability of freely dried sheets. As the amounts of MFC increased the effects on dimensional stability became more severe. However the fineness of MFC didn’t play any important role. Both hygroexpansion and drying shrinkage were decreased with cationic starch addition. Prevention of drying shrinkage over powered the effects of additives on hygroexpansion. Tensile strength improved up till 7 % addition amount which could be set as the upper limit of MFC addition when paper preparation and tensile strength are concerned.
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The physicochemical composition of pure royal jelly as well as of some adulterated samples was analyzed by determining moisture, ash, lipids, nitrogen/proteins, carbohydrates, starch and 10- HDA (10-hydroxy-2-decenoic acid). The solubility in alkaline medium was used to detect the main frauds for adulterating royal jelly which comprise addition of yogurt, water, egg white, sweet condensed milk mixed with propolis, unripe banana and corn starch slurry.
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A new titrimetric method for the determination of phosphite in fertilizer samples, based on reaction of H3PO3 with standard iodine solution in neutral media, is proposed. Diluted samples containing ca. 0.4% m/v P2O5 are heated and titrated with 0.05 mol L-1 iodine standard until the solution becomes faint yellow. Back titration is also feasible: a slight excess of titrant is added followed by starch indicator and titration is completed taking as the end point the change in color from blue to colorless. The influence of chemical composition and pH of buffers, temperature and foreign species on waiting time and end-point detection were investigated. For the Na2HPO4/NaH2PO4 buffer (pH 6.8) at 70 °C, the titration time was 10 min, corresponding to about 127 mg iodine, 200 mg KI and 174 mg Na2HPO4 and 176 mg NaH2PO4 consumed per determination. Accuracy was checked for phosphite determination in seven fertilizer samples. Results obtained by the proposed procedure were in agreement with those obtained by spectrophotometry at 95% confidence level. The R.S.D. (n=10) for direct and back titration was 0.4% and 1.3% respectively.
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Least-squares support vector machines (LS-SVM) were used as an alternative multivariate calibration method for the simultaneous quantification of some common adulterants found in powdered milk samples, using near-infrared spectroscopy. Excellent models were built using LS-SVM for determining R², RMSECV and RMSEP values. LS-SVMs show superior performance for quantifying starch, whey and sucrose in powdered milk samples in relation to PLSR. This study shows that it is possible to determine precisely the amount of one and two common adulterants simultaneously in powdered milk samples using LS-SVM and NIR spectra.
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Polysaccharide-based drilling fluids have been often applied in horizontal wells of petroleum reservoirs in Campos, Rio de Janeiro. The present study aimed to understand the mechanism of adsorption and desorption of the drill-in fluid, xanthan, modified starch and lubricant on SiO2 by means of ellipsometry. The effect of pH and brine on the mean thickness (D) of adsorbed layer was systematically investigated. The adsorption was mainly favored under alkaline conditions. A model has been proposed to explain this effect. The adsorption isotherms determined separately for xanthan and starch on SiO2 surfaces could be fitted with the Langmuir model, which yielded similar adsorption constant values.