Polipeptídeos e proteínas com influência na qualidade da espuma da cerveja e métodos analíticos utilizados no seu estudo

A review of polypeptides and proteins that influence, direct or indirectly, beer foam quality, as well as the most relevant analytical methods used in their study, are presented. Protein Z, LTP1 and hordein/glutelin fragments originated from malt have a direct influence on beer foam quality. Other proteins, like malt hordeins and albumins and wheat puroindolines, are, to some degree, also important for beer foam quality. Protein hydrophobicity is pointed out as a key parameter to enhance foam quality. Electrophoretic, chromatographic and immunological analytical methods are currently used to study polypeptides and proteins present in barley, malt, wort, beer, and foam. Best results are obtained when combinations of these methods are applied.

Uso da pressão gerada por uma coluna de água para controle da vazão em sistemas de análises em fluxo

This work presents a new approach to control the flow rate in hydrodynamic flow experiments. The combination of air pressure generated by an aquarium air pump and the pressure generated by a water column were used for this purpose. This device supports a stable flow rate without pulsation for a long period of time. Furthermore, the flow rate can be easily controlled at various values in one or more streams. The performance of this approach was investigated using Fe(CN)6(4-) solutions in flowing systems using amperometric and voltammetric detection in wall-jet configuration. The results showed that the performance of the proposed device was better than a commercial peristaltic pump. It suggests that this approach can be used successfully in flow analysis systems.

Kehittyneiden hitsausprosessien soveltuvuus alumiinin ja hiiliterästen hitsaukseen

Diplomityössä tutkitaan hitsausprosessien kehitystä. Työn kirjallisen osan alku kuvaa hitsauksen nykypäivää ja tulevaisuutta sekä millainen on hitsaava Suomi. Kehittyneiden hitsausprosessien tarkastelu on jaettu hiiliterästen ja alumiinien hitsausprosesseihin. Hiiliteräksien hitsauksen osalta työssä esitellään kitkahitsaus pyörivällä työkalulla, muunnettu lyhytkaarihitsaus, laserhitsaus, laser-hybridihitsaus ja kapearailohitsaus. Alumiinien hitsauksen osalta työssä esitellään laserhitsaus, muunnettu lyhytkaarihitsaus, kitkahitsaus pyörivällä työkalulla ja vaihtovirta MIG hitsaus. Diplomityön käytännönosuudessa todennettiin hitsausprosessien kehitys. Ensimmäisissä hitsauskokeissa hitsattiin merialumiinia eri kaarityypeillä. Vertailua tehdään pulssihitsauksen, lankapulssihitsauksen sekä CMT-kaarihitsauksen välillä. Koehitsaukset osoittavat CMT-hitsauksen tuottavan MIG-pulssihitsausta pienemmät hitsausmuodonmuutokset. CMT-hitsauksessa alumiinin oksidikerros aiheuttaa MIGpulssihitsausta vähemmän ongelmia, sillä kaari syttyy varmemmin suurillakin hitsausnopeuksilla, eikä hitsiin synny huokosia. Hitsausnopeudella 40 cm/min lankapulssihitsauksella ja MIG-pulssihitsauksella päittäisliitoksena hitsattujen vesileikattujen alumiinikappaleiden hitseihin ei syntynyt huokosia. Kokeen perusteella voidaan todeta, ettei oksidikerroksella ollut vaikutusta hitsin onnistumiseen. Hitsauskokeiden toinen osio tutkii hiilimangaaniteräksisen T-palkin kuitulaserhitsausta. Viiden kilowatin laserteholla hitsattiin onnistuneesti viisi metriä pitkiä T-palkkeja hitsausnopeudella 2 m/min. Takymetrimittauksella ja Tritop 3D-koordinaattimittauksella todennettiin laserhitsatun T-palkin hitsausmuodonmuutosten olevan huomattavasti Twin-jauhekaarihitsauksella hitsattua T-palkkia pienemmät.

Construção de um sistema simples e compacto de recirculação d'água sob pressão para trompa d'água

Vacuum pumps are very useful in physical, chemical and biological experiments. In this communication it is described the design of a compact and low cost water recirculating system employing a water-jet aspirator pump as the vacuum source. The system requires only a water pump, water-jet aspirator pump, commercial PVC water tubes and a drain connection.

Estudo da sorção do corante catiônico violeta cristal por espuma de poliuretano em meio aquoso contendo dodecilsulfato de sódio

This work presents a detailed study about the sorption of crystal violet (CV) cationic dye onto polyether type polyurethane foam (PUF). The sorption process was based on the formation of an ionic-pair between cationic dye and dodecylsulfate anion (SDS), which presented high affinity by PUF. Set-up employed in the study was built up by adjusting a 200 mg cylinder of PUF to the arm of an overhead stirrer. The system was characterized in relation to equilibrium and kinetic aspects and it was modeled by employing Langmuir and Freundlich isotherms. Obtained results showed that the ratio between SDS and MB concentrations played an important role on the sorption process. According to results found it was possible to retain up to 3.4 mg of dye from 200 mL of a 5.0 x 10-5 mol L-1 CV solution containing 1.25 x 10-4 mol L-1 SDS, which represented a removal efficiency of around 92%.

Construção e caracterização de um detector eletroquímico para análises em fluxo

The present work describes a low-cost electrochemical "wall-jet" detector for flow analysis. The electrolytic solution enters into the cell through a tube of stainless steel (200 to 300 µm i.d), reaching to the center of the working electrode perpendicularly and then being mixed to the remaining solution in the cell, which flows under atmospheric pressure into a waste reservoir. The proposed electrochemical detector can be used with any type of working electrode, from commercial to home-made, such as glassy carbon and metallic electrodes (modified or unmodified), which enlarge the applications of the electrochemical detector.

Produção e caracterização de espumas cerâmicas obtidas a partir de lodo de anodização de alumínio

Ceramic foams were produced from a sludge generated in the aluminum anodizing process by using an industrial polyurethane foam (replication method) with open cell sizes of 10 ± 5 ppi (porosity = 97%) which were impregnated with suspensions containing 50-61 wt.% alumina, 1 wt.% citric acid, 6 wt.% bentonite and fired at 1600 ºC for 2 h. The aluminum anodizing sludge shows a high alumina content (87.5 wt.%) and a low particle size (~1.7 mm) after calcination and milling. The obtained filters show porosity of approximately 70%, filtration capability (mass water flow) of 1.7 kg/s and mechanical strength under compression of 2.40 MPa.

Processamento de cartuchos de impressoras de jato de tinta: um exemplo de gestão de produto pós-consumo

This work presents a route for processing spent ink-jet cartridges in an experimental course. The disassembly of the cartridges requires several steps and the recognition of their different components is essential to define the best final destination (recycling, co-processing). The plastic strips were chemically processed so as to recover gold and copper. The students recognized the difficulty of processing multicomponent wastes and the importance of the chemical work under the best safety conditions; they also experienced many laboratory techniques and recognized the value of the selective collection and the reverse logistics to reach a viable commercial scale recycling.

Química e sustentabilidade: novas fronteiras em biocombustíveis

This contribution discusses the state of the art and the challenges in producing biofuels, as well as the need to develop chemical conversion processes of CO2 in Brazil. Biofuels are sustainable alternatives to fossil fuels for providing energy, whilst minimizing the effects of CO2 emissions into the atmosphere. Ethanol from fermentation of simple sugars and biodiesel produced from oils and fats are the first-generation of biofuels available in the country. However, they are preferentially produced from edible feedstocks (sugar cane and vegetable oils), which limits the expansion of national production. In addition, environmental issues, as well as political and societal pressures, have promoted the development of 2nd and 3rd generation biofuels. These biofuels are based on lignocellulosic biomass from agricultural waste and wood processing, and on algae, respectively. Cellulosic ethanol, from fermentation of cellulose-derived sugars, and hydrocarbons in the range of liquid fuels (gasoline, jet, and diesel fuels) produced through thermochemical conversion processes are considered biofuels of the new generation. Nevertheless, the available 2nd and 3rd generation biofuels, and those under development, have to be subsidized for inclusion in the consumer market. Therefore, one of the greatest challenges in the biofuels area is their competitive large-scale production in relation to fossil fuels. Owing to this, fossil fuels, based on petroleum, coal and natural gas, will be around for many years to come. Thus, it is necessary to utilize the inevitable CO2 released by the combustion processes in a rational and economical way. Chemical transformation processes of CO2 into methanol, hydrocarbons and organic carbonates are attractive and relatively easy to implement in the short-to-medium terms. However, the low reactivity of CO2 and the thermodynamic limitations in terms of conversion and yield of products remain challenges to be overcome in the development of sustainable CO2 conversion processes.

Koneinvestoinnin suunnittelu valmistavaan teollisuuteen

Tämän diplomityön tavoitteena oli tutustua ohutlevyjen nykyaikaisiin koneellisiin leikkausmenetelmiin ja tutkia niiden soveltuvuutta yrityksen tarpeisiin. Kohdeyrityksessä investoinnin tarve jakautui tuottavuusinvestoinnin, korvausinvestoinnin ja strategisen investoinnin kesken. Tavoitteena oli luoda investointipolku, jonka avulla poissuljettiin menetelmät, jotka eivät soveltuneet yrityksen tuotantoon. Työn kirjallisuusosuudessa tarkastellaan teoriatietoja, jotka liittyvät yleisesti nykyaikaisiin ohutlevyjen leikkausmenetelmiin sekä investointiprojektin suunnitteluun ja toteutuksen teoriaan. Lisäksi käsitellään investointeihin liittyviä kannattavuus- ja kustannuslaskennan perusperiaatteita. Työn empiirisessä osassa selvitettiin yrityksen ohutlevyosien valmistuksen periaatteita nykytila-analyysin avulla. Tämän perusteella määritettiin nykyaikaisista markkinoilla olevista menetelmistä yritykselle soveltuvin. Tutkimuksen perusteella laserleikkaus oli menetelmistä soveltuvin. Perusinvestoinniltaan laser oli vaihtoehtoisista menetelmistä kallein, mutta se soveltui käytettävyyden, tehokkuuden, joustavuuden ja muiden ominaisuuksiensa perusteella parhaiten tuotannon tarpeisiin. Työn merkittävimmät tulokset osoittivat, että investoinnin kannattavuus riippui koneelle saatavasta käyttösuhteesta. Uusien koneiden tehokkuus lyhentäisi tuotannon läpimenoaikoja, mutta ilman riittävää kapasiteetin käyttöastetta kappaleiden omakustannusarvo nousisi. Lopputulokset ja suositukset on esitetty työn lopussa.

Ultrakevyen rahtialuksen kansiluukkujen sekä luukkujen siirto- ja varastointijärjestelmän suunnittelu hyödyntäen kevytrakennekonsepteja

Tämän työn tarkoituksena oli tutkia miten rahtialuksen kansiluukut voitaisiin valmistaa mahdollisimman kevyiksi. Katettavan ruuman pinta-ala on n. 10 m x 40 m. Luukkujen suuresta jännevälistä johtuen, rakenteelta vaaditaan suurta jäykkyyttä. Erilaisina vaihtoehtoina tutkittiin vaahtomaista alumiinia, alumiinisia kennorakenteita ja polyuretaanisia sandwich-rakenteita. Työssä vertailtiin myös erilaisia geometrisia ratkaisuja, joilla kansiluukkujen jäykkyyttä pyrittiin lisäämään ja sitä kautta pääsemään pienempään materiaalin tarpeeseen. Geometriaa suunniteltaessa huomioitiin myös vaikutukset ruuman tilavuuteen ja lainsäädännön asettamat reunaehdot. Lainsäädännöstä saatiin esimerkiksi turvakaiteiden minimikorkeus, joka vaikuttaa suoraan ruuman tilavuuteen, kun aluksen korkeimmaksi kohdaksi on valittu laivan keskilinja ja tämä korkeus on annettu suunnittelun lähtötietona. Tietokoneavusteisen lujuuslaskennan avulla eri vaihtoehdoista muodostettiin elementtimallit. Malleja varioimalla ja tuloksia vertailemalla saatiin selville kevyin mahdollinen rakenne ja geometria. Malleista saatiin selville myös luukkujen tukireaktiovoimat, eli voimat, jotka luukut kohdistavat aluksen muihin rakenteisiin. Lisäksi työssä mietittiin erilaisia tapoja ruuman avaamiseen ja avaamistavan vaikutusta kansiluukkujen painoon, geometriaan ja ruuman tilavuuteen.

Use of experimental design in the optimisation of a solid phase preconcentration system for Cobalt determination by GFAAS

In this work is proposed a solid phase preconcentration system of Co2+ ions and its posterior determination by GFAAS in which fractional factorial design and response surface methodology (RSM) were used for optimization of the variables associated with preconcentration system performance. The method is based on cobalt extraction as a complex Co2+-PAN (1:2) in a mini-column of polyurethane foam (PUF) impregnated with 1-(2-pyridylazo)-naphthol (PAN) followed by elution with HCl solution and its determination by GFAAS. The chemical and flow variables studied were pH, buffer concentration, eluent concentration and preconcentration and elution flow rates. Results obtained from fractional factorial design 2(5-1) showed that only the variables pH, buffer concentration and interaction (pH X buffer concentration) based on analysis of variance (ANOVA) were statistically significant at 95% confidence level. Under optimised conditions, the method provided an enrichment factor of 11.6 fold with limit of detection and quantification of 38 and 130 ng L-1, respectively, and linear range varying from 0.13 to 10 µg L-1. The precision (n = 9) assessed by relative standard deviation (RSD) was respectively 5.18 and 2.87% for 0.3 and 3.0 µg L-1 cobalt concentrations.

Determinação amperométrica de iodeto em soluções expectorantes orais com análise por injeção em fluxo usando a reação iodeto/nitrito

Neste trabalho foi desenvolvido um sistema de injeção em fluxo visando à determinação amperométrica de íons iodeto em soluções expectorantes. O método é baseado na reação do iodeto com íons nitrito em meio ácido. O iodo formado é monitorado por amperometria no potencial de +200 mV vs. Ag/AgCl (3 mol L-1), usando um eletrodo de trabalho de disco de platina (RDE) com raio = 0,75 mm adaptado a uma célula eletroquímica "wall-jet". O sistema em fluxo foi usado com o carregador impulsionado pela pressão gravitacional dos reagentes (carregador: solução 2 x 10-4 mol L-1 em NaNO2 e 0,2 mol L-1 em H2SO4), na vazão de 4 mL min-1. O método é rápido (acima de 100 injeções h-1) e preciso (RSD = 1,9%; n=10 e C I 8 x 10-6 mol L-1), apresentando um limite de detecção de 20 ng I- ou 8 x 10-7 mol L-1 (3SD). A validação do método proposto foi realizada seguindo as normas USP, ou seja, titulação potenciométrica com AgNO3 0,100 mol L-1 e os resultados obtidos mostraramse concordantes com os valores de referência do fabricante.

Morphological and thermal analyses of flexible polyurethane foams containing commercial calcium carbonate

One filler often utilized in flexible polyurethane foams is calcium carbonate (CaCO3) because it is non-abrasiveness, non-toxicity and facilitated pigmentation. However, it is observed that the excess of commercial CaCO3 utilized in industry possibly causing permanent deformations and damaging the quality of the final product. The effect of different concentrations of commercial CaCO3, in flexible foams, was studied. Different concentrations of CaCO3 were used for the synthesis of flexible polyurethane foams, which were submitted to morphological and thermal analyses to verify the alterations provoked by the progressive introduction of this filler.

L'ontologie chez Heidegger et chez Lukacs - Phénoménologie et dialectique

L'auteur de ce texte a abordé auparavant à plusieurs reprises le sujet d'une confrontation entre les pensées de Heidegger et de Lukacs. Il est parti de l'idée qu'ils existent des motifs communs entre les deux pensées, par exemple le thème de l'aliénation et celui de la réification, et il a publié deux articles dans ce sens. Le texte publié ici poursuit un objectif plus ambitieux, car il se propose de remonter aux fondements ontologiques des deux pensées et confronter Heidegger et Lukacs à partir de leur opposition sur pluseurs questions philosophiques cruciales : l'autonomie ontologique du monde extérieur, la définition du concept de "monde", la "subjectivité du sujet" et la humanitas de l'homo humanus, la critique lukacsienne du concept heideggérien d'"être-jeté..." (Geworfenheit),la problématique de la finitude et de l'infini,etc. La thèse centrale de l'article est l'occultation par Heidegger du travail comme "phénomène originaire" de l'existence humaine et sa substitution par une catégorie affective: le "Souci" (die Sorge), tandis que Lukacs a construit son ontologie de l'être social, en suivant Hegel et Marx, sur l'idée du travail comme pivot de l'existence humaine. La partie finale du texte désigne plusieurs motifs de la pensée heideggérienne (la critique de la pensée sécurisante, par ex.) qui préfigurent l'adhésion du philosophe à l'extrême droite de l'époque, ce qui confirme la thèse de Lukacs formulée dans son livre La Destruction de la Raison sur le caractère "pré-fasciste" de certaines orientations de la philosophie heideggérienne à l'époque qui asuccédé à son livre fameux Être et Temps.