Cromatografia líquida capilar: estado da arte e aplicações

This review describes the advantages and disadvantages of using capillary liquid chromatography (CLC), which is considered the newest member in the analytical separation science arsenal. Although CLC has tremendous potential for being the next major innovation in separatory analysis, it has not yet obtained great popularity compared to conventional high performance (and ultra-high performance) liquid chromatography. Comparisons are made between these techniques and some of the reasons that CLC has not yet reached its potential will be advanced.

Super/subcritical fluid chromatography with packed columns: state of the art and applications

Separations using supercritical fluid chromatography (SFC) with packed columns have been re-discovered and explored in recent years. SFC enables fast and efficient separations and, in some cases, gives better results than high performance liquid chromatography (HPLC). This paper provides an overview of recent advances in SFC separations using packed columns for both achiral and chiral separations. The most important types of stationary phases used in SFC are discussed as well as the most critical parameters involved in the separations and some recent applications.

DETECTION AND QUANTIFICATION OF PHYTOCHEMICAL MARKERS OF Ilex paraguariensis BY LIQUID CHROMATOGRAPHY

Ilex paraguariensis (yerba-mate) is used as a beverage, and its extract requires adequate quality control methods in order to guarantee quality and safe use. Strategies to develop and optimize a chromatographic method to quantify theobromine, caffeine, and chlorogenic acid in I. paraguariensis extracts were evaluated by applying a quality by design (QbD) model and ultra high-performance liquid chromatography (UHPLC). The presence of these three phytochemical markers in the extracts was evaluated using UHPLC-MS and was confirmed by the chromatographic bands in the total ion current traces (m/z of 181.1 [M+H]+, 195.0 [M+H]+, and 353.0 [M−H]−, respectively). The developed method was then transferred to a high-performance liquid chromatography (HPLC) platform, and the three phytochemical markers were used as external standards in the validation of a method for analyses of these compounds in extracts using a diode array detector (DAD). The validated method was applied to quantify the chlorogenic acid, caffeine, and theobromine in the samples. HPLC-DAD chromatographic fingerprinting was also used in a multivariate approach to process the entire data and to separate the I. paraguariensis extracts into two groups. The developed method is very useful for qualifying and quantifying I. paraguariensis extracts.

COMPARAÇÃO DE MÉTODOS POR CROMATOGRAFIA LÍQUIDA NA DETERMINAÇÃO DE MULTIRRESÍDUOS DE AGROTÓXICOS EM MORANGOS

Liquid chromatography is often used for the determination of pesticide multiresidues in foods. In Brazil, the strawberry crop is an example of a food with high levels of irregularities because of the application of pesticides. This is a major concern from the perspective of food safety, environmental protection, and certification for food export. The purpose of this study is to evaluate and compare chromatographic separation and detection methods in relation to a newly developed and validated method using ultra high performance liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) for the analytical determination of pesticides in strawberries. The comparisons were based on evaluations of the analysis time, consumption of the solvent in the mobile phase, injection volume, detectability, matrix effect, and recovery. The results showed that the LC–MS/MS and UHPLC–MS/MS techniques were both extremely efficient at analyzing pesticide residues with different physico-chemical parameters that were present at low concentrations in a complex matrix. The UHPLC separation method provided better chromatographic performance and productivity, which contributed favorably to routine analytical determinations. Detection by MS/MS had better detectability and selectivity compared with the diode array detector.

Ultralujasta teräksestä valmistetun liitoksen pienahitsin staattinen kestävyys

Ultralujat teräkset ovat teräksiä, joiden lujuus on reilusti suurempi verrattuna perinteisiin rakenneteräksiin. Niiden ominaisuuksia hyödynnetään eniten nosto- ja kuljetusvälinete¬ollisuudessa. Ultralujien terästen käyttö avaa suunnittelijalle uusia mahdollisuuksia suun¬nitella ulottuvampia ja kevyempiä rakenteita, jolloin voidaan saavuttaa säästöjä niin val¬mistus- kuin polttoainekustannuksissakin. Ultralujille teräksille ei kuitenkaan ole ole¬massa niitä vastaavia suunnitteluohjeita tai standardeja. Teräsrakenteiden liitosten suun¬nitteluun mitoitusohjeita antava standardi SFS-EN 1993-1-8 ei huomioi teräksiä, joiden myötölujuus on yli 460 MPa. SFS-EN 1993-1-12 on 1993-1-8:n laajennus, joka on voi¬massa myötölujuuteen 700 MPa asti. Tässä diplomityössä tutkittiin ultralujista teräksistä valmistettujen pienahitsiliitosten käyttäytymistä vetokokeiden ja elementtimenetelmän avulla. Tulosten avulla voitiin mää¬rittää matalalujuuksisten terästen mitoitusohjeiden soveltuvuutta ultralujille teräksille. Kokeissa käytetty teräs oli Ruukin valmistama Optim 960 QC.

Use data from permanent sampling points in growth and yield modeling

This study was carried to evaluate the efficiency of the Bitterlich method in growth and yield modeling of the even-aged Eucalyptus stands. 25 plots were setup in Eucalyptus grandis cropped under a high bole system in the Central Western Region of Minas Gerais, Brazil. The sampling points were setup in the center of each plot. The data of four annual mesurements were colleted and used to adjust the three model types using the age, the site index and the basal area as independent variables. The growths models were fitted for volume and mass of trees. The efficiency of the Bitterlich method was confirmed for generating the data for growth and yield modeling.

Modeling of electrolyte sorption – from phase equilibria to dynamic separation systems

In this thesis, general approach is devised to model electrolyte sorption from aqueous solutions on solid materials. Electrolyte sorption is often considered as unwanted phenomenon in ion exchange and its potential as an independent separation method has not been fully explored. The solid sorbents studied here are porous and non-porous organic or inorganic materials with or without specific functional groups attached on the solid matrix. Accordingly, the sorption mechanisms include physical adsorption, chemisorption on the functional groups and partition restricted by electrostatic or steric factors. The model is tested in four Cases Studies dealing with chelating adsorption of transition metal mixtures, physical adsorption of metal and metalloid complexes from chloride solutions, size exclusion of electrolytes in nano-porous materials and electrolyte exclusion of electrolyte/non-electrolyte mixtures. The model parameters are estimated using experimental data from equilibrium and batch kinetic measurements, and they are used to simulate actual single-column fixed-bed separations. Phase equilibrium between the solution and solid phases is described using thermodynamic Gibbs-Donnan model and various adsorption models depending on the properties of the sorbent. The 3-dimensional thermodynamic approach is used for volume sorption in gel-type ion exchangers and in nano-porous adsorbents, and satisfactory correlation is obtained provided that both mixing and exclusion effects are adequately taken into account. 2-Dimensional surface adsorption models are successfully applied to physical adsorption of complex species and to chelating adsorption of transition metal salts. In the latter case, comparison is also made with complex formation models. Results of the mass transport studies show that uptake rates even in a competitive high-affinity system can be described by constant diffusion coefficients, when the adsorbent structure and the phase equilibrium conditions are adequately included in the model. Furthermore, a simplified solution based on the linear driving force approximation and the shrinking-core model is developed for very non-linear adsorption systems. In each Case Study, the actual separation is carried out batch-wise in fixed-beds and the experimental data are simulated/correlated using the parameters derived from equilibrium and kinetic data. Good agreement between the calculated and experimental break-through curves is usually obtained indicating that the proposed approach is useful in systems, which at first sight are very different. For example, the important improvement in copper separation from concentrated zinc sulfate solution at elevated temperatures can be correctly predicted by the model. In some cases, however, re-adjustment of model parameters is needed due to e.g. high solution viscosity.

Modern Metallic Materials for Arctic Environment

This thesis is part of the Arctic Materials Technologies Development –project, which aims to research and develop manufacturing techniques, especially welding, for Arctic areas. The main target of this paper is to clarify what kind of European metallic materials are used, or can be used, in Arctic. These materials include mainly carbon steels but also stainless steels and aluminium and its alloys. Standardized materials, their properties and also some recent developments are being introduced. Based on this thesis it can be said that carbon steels (shipbuilding and pipeline steels) have been developed based on needs of industry and steels exist, which can be used in Arctic areas. Still, these steels cannot be fully benefited, because rules and standards are under development. Also understanding of fracture behavior of new ultra high strength steels is not yet good enough, which means that research methods (destructive and non-destructive methods) need to be developed too. The most of new nickel-free austenitic and austenitic-ferritic stainless steels can be used in cold environment. Ferritic and martensitic stainless steels are being developed for better weldability and these steels are mainly developed in nuclear industry. Aluminium alloys are well suitable for subzero environment and these days high strength aluminium alloys are available also as thick sheets. Nanotechnology makes it possible to manufacture steels, stainless steels and aluminium alloys with even higher strength. Joining techniques needs to be developed and examined properly to achieve economical and safe way to join these modern alloys.

Jännityssuhteen vaikutus ultralujan teräksen hitsausliitoksen väsymislujuuteen

Aiempien ultralujia teräksiä koskevien tutkimusten jatkoksi tässä diplomityössä keskityttiin jännityssuhteen varioinnin tuomien ilmiöiden esille tuomiseen koesauvojen väsytyskoestuk-sessa. Pohjana diplomityölle ovat mm. Timo Björkin tutkimustulokset ULTRASTEEL-hankkeesta sekä Tuomas Skrikon kandidaatintyöhönsä koostamat väsytyskoetulokset. Testattujen 12 koesauvan väsytyskoetulosten perusteella jännityssuhteen kasvattaminen alen-taa hitsattujen ultralujien teräsrakenteiden FAT-luokitusta. FAT-luokkien ja jännityssuhteen välillä on havaittu säännönmukaisuutta ja huomattavaa FAT-luokituksen lasku on jännitys-suhteen 0.35 jälkeen. Jälkikäsiteltyjen koesauvojen FAT-luokat ovat jälkikäsittelemättömiä parempia. Myös käsit-telemättömillä sauvoilla päästään mekanisoidussa MAG-hitsauksessa keskimääräisen kone-pajalaadun FAT = 100 MPa yläpuolelle.

Ultralujien terästen pienahitsien staattinen lujuus

Kandidaatintyön tarkoituksena oli selvittää hitsausliitosten mitoitusohjeita ultralujille teräksille. Työhön kuului laboratoriotestauksia, joiden avulla tarkasteltiin laskujen soveltuvuutta ultralujille teräksille. Laskuissa verrattiin erityisesti kimmoteorian ja plastisuusteorian toimivuutta. Työn tuloksena tuotettiin mitoitusohjeet otsapienahitseille, eli mitoitusvoimaan nähden poikittaisille hitseille. Myös kylkipienahitseille, eli mitoitusvoimaan nähden yhdensuuntaisille hitseille saatiin alustavia tuloksia.

Experimental poisoning by Baccharis megapotamica var. weirii in buffalo

Five male 6-8 month-old Murrah buffalo calves were orally dosed with the fresh aerial parts of Baccharis megapotamica var. weirii at doses of 1, 3, 4, 5 and 10g/kg body weight (bw) (~1-10mg macrocyclic trichothecenes/kg/bw). The B. megapotamica used for the experiment was harvested on a farm where a recent spontaneous outbreak of poisoning caused by such plant had occurred. Clinical signs appeared 4-20 hours and 4 buffaloes died 18-49 hours after the ingestion of the plant. Clinical signs were apathy, anorexia, and watery diarrhea, fever, colic, drooling, muscle tremors, restlessness, laborious breathing and ruminal atony, and dehydration. The most consistent gross findings were restricted to the gastrointestinal (GI) tract consisted of varying degrees of edema and reddening of the mucosa of the forestomach. Histopathological findings consisted of varying degrees of necrosis of the epithelial lining of the forestomach and of lymphocytes within lymphoid organs and aggregates. Fibrin thrombi were consistently found in sub-mucosal vessels of the forestomach and in the lumen of hepatic sinusoids. It is suggested that dehydration, septicemia and disseminated intravascular coagulation participate in the pathogenesis of the intoxication and play a role as a cause of death. A subsample of B. megapotamica var. weirii was frozen-dried and ground and analyzed using UHPLC (Ultra High Performance Liquid Chromatography) with high resolution Time of Flight mass spectrometry and tandem mass spectrometry, it was shown that the plant material contained at least 51 different macrocyclic trichothecenes at a total level of 1.1-1.2mg/g. About 15-20% of the total trichothecenes contents was found to be monosaccharide conjugates, with two thirds of these being glucose conjugates and one third constituted by six aldopentose conjugates (probably xylose), which has never been reported in the literature.

Adaptive Routing Approaches for Networked Many-Core Systems

Through advances in technology, System-on-Chip design is moving towards integrating tens to hundreds of intellectual property blocks into a single chip. In such a many-core system, on-chip communication becomes a performance bottleneck for high performance designs. Network-on-Chip (NoC) has emerged as a viable solution for the communication challenges in highly complex chips. The NoC architecture paradigm, based on a modular packet-switched mechanism, can address many of the on-chip communication challenges such as wiring complexity, communication latency, and bandwidth. Furthermore, the combined benefits of 3D IC and NoC schemes provide the possibility of designing a high performance system in a limited chip area. The major advantages of 3D NoCs are the considerable reductions in average latency and power consumption. There are several factors degrading the performance of NoCs. In this thesis, we investigate three main performance-limiting factors: network congestion, faults, and the lack of efficient multicast support. We address these issues by the means of routing algorithms. Congestion of data packets may lead to increased network latency and power consumption. Thus, we propose three different approaches for alleviating such congestion in the network. The first approach is based on measuring the congestion information in different regions of the network, distributing the information over the network, and utilizing this information when making a routing decision. The second approach employs a learning method to dynamically find the less congested routes according to the underlying traffic. The third approach is based on a fuzzy-logic technique to perform better routing decisions when traffic information of different routes is available. Faults affect performance significantly, as then packets should take longer paths in order to be routed around the faults, which in turn increases congestion around the faulty regions. We propose four methods to tolerate faults at the link and switch level by using only the shortest paths as long as such path exists. The unique characteristic among these methods is the toleration of faults while also maintaining the performance of NoCs. To the best of our knowledge, these algorithms are the first approaches to bypassing faults prior to reaching them while avoiding unnecessary misrouting of packets. Current implementations of multicast communication result in a significant performance loss for unicast traffic. This is due to the fact that the routing rules of multicast packets limit the adaptivity of unicast packets. We present an approach in which both unicast and multicast packets can be efficiently routed within the network. While suggesting a more efficient multicast support, the proposed approach does not affect the performance of unicast routing at all. In addition, in order to reduce the overall path length of multicast packets, we present several partitioning methods along with their analytical models for latency measurement. This approach is discussed in the context of 3D mesh networks.

FE-analyysin soveltaminen S960 QC teräksisen I-profiilin äärikestävyyden määrittämisessä

Tässä työssä tutkittiin FE-analyysin soveltamista S960 QC teräksisen I-profiilin kestävyyden määrittämisessä. Työn tavoitteena oli tarkastella nykyisten suunnitteluohjeiden soveltuvuutta ultralujille teräksille ja koota ohjemateriaali I-profiilin optimoimisesta sekä FE-analyysin hyö-dyntämisestä I-profiilin staattisen ja dynaamisen kestävyyden määrittämisessä. I-profiili mitoitettiin ja optimoitiin Eurokoodi 3:ssa esitettyjen PL3 mukaisten mitoitusohjeiden avulla. Rakenteelle suoritettiin Eurokoodi 3:n ja IIW:n mukaiset lommahdus-, kiepahdus- ja vä-symiskestävyystarkastelut. Väsymistarkastelussa sovellettiin nimellisen jännityksen, rakenteelli-sen jännityksen ja tehollisen lovijännityksen menetelmiä sekä murtumismekaniikkaa. Rakenteel-lisen jännityksen menetelmässä sovellettiin lisäksi lineaarista ja parabolista pintaa pitkin ekstra-polointia, paksuuden yli linearisointia sekä Dong:in menetelmää. Lommahdus-, kiepahdus- ja väsymistarkasteluissa hyödynnettiin analyyttistä laskentaa, FE-analyysiä sekä Frank2d sovellusta. Tarkastelujen perusteella voidaan todeta, että analyyttisillä menetelmillä saadaan numeerisia me-netelmiä varmemmalla puolella olevia tuloksia. Lommahdustarkastelussa ero tulosten välillä on suurimmillaan 8 % ja kiepahdustarkastelussa suurimmillaan 20 % mutta väsymistarkastelussa saadut tulokset eroavat keskenään huomattavasti. Väsymistarkastelussa tehollisen lovijännityksen menetelmällä sekä rakenteellisen jännityksen menetelmän Dong:in menetelmällä saadaan huo-mattavasti muita menetelmiä pidempiä kestoikiä, kun taas yksinkertaisemmilla menetelmillä saa-dut kestoiät ovat lyhyempiä. Rakenteen kestävyyden määrittäminen analyyttisillä menetelmillä on melko helppoa, mutta tu-lokset ovat monesti liian konservatiivisia. FE-analyysillä saadaan puolestaan hyvin tarkkoja tu-loksia mallin ollessa yksityiskohtainen. Mallintaminen on kuitenkin aikaa ja resursseja vievää ja vaatii käyttökokemusta. FE-analyysin mahdolliset hyödyt on aina arvioitava tapauskohtaisesti tarkasteltavan geometrian, kuormitusten ja reunaehtojen perusteella.