Determinação de isotiocianato de benzila em Carica papaya utilizando cromatografia gasosa com detectores seletivos

In the present work, a method was developed and validated for the quantification of benzyl isothiocyanate (BITC) in the fruits of Carica papaya. The quantification of this compound was carried out by gas chromatography (GC) with selective detectors - nitrogen phosphorus detector (NPD) and flame photometric detector (FPD). The performance of these detectors showed a higher sensitivity of the NPD with a broader linear range of detection. The LOD/LOQ were 0.038/0.100 µg/mL for NPD and 5.78/19.29 µg/mL for FPD. The recovery of the method for BITC was 90,64%. An average value of BITC concentration in all the analyzed samples was 16,23 µg BITC/g.

Sensortizació en aplicacions alimentàries

La societat actual es caracteritza pel seu ús intensiu i extensiu de les telecomunicacions, que ha esdevingut possible gràcies a la microelectrònica i altres tecnologies. Abans, la microelectrònica ja havia deixat la seva empremta en l’automatització i la computació, on la reducció de costos que hi aportava havia anat fent viables cada vegada més aplicacions. Aquest fet ha esdevingut particularment clar en l’automoció on fa relativament pocs anys els elements electrònics tenien un rol marginal i ara constitueixen una part important de tota mena de vehicles. Però mentre aquestes aplicacions afectaven principalment les màquines, les telecomunicacions involucren majoritàriament les persones i això ha implicat un esforç tecnològic addicional per aconseguir que els nous dispositius fossin assequibles per a molt usuaris.Aquest cicle “nova tecnologia que permet noves aplicacions que redueixen el cost de la tecnologia i això fa viables noves aplicacions”, no queda tancat dins cap àmbit d’aplicació sinó que té una dimensió totalment transversal. Els sensors, molts d’ells basats en tecnologies microelectròniques, són un paradigma del caràcter transversal de la tecnologia fins el punt que han esdevingut omnipresents, també en aplicacions alimentàries, tot i que encara hi hagi molts reptes per afrontar.En aquesta ponència s’exposaran en primer lloc els fonaments dels sensors i alguns dels avenços tecnològics que han marcat la seva evolució en els darrers anys. Després es revisaran algunes de les aplicacions actuals dels sensors en la indústria alimentària i els factors singulars que per una banda requereixen la incorporació de nous sensors i que per altra impedeixen que aquesta incorporació es pugui fer mitjançant la simple adaptació de solucions aplicades en altres indústries. Finalment, s’exposaran algunes tendències que es preveu que poden influir notablement en una major implantació dels sensors actuals i en el desenvolupament de nous sensors.

Internal standard versus external standard calibration: an uncertainty case study of a liquid chromatography analysis

Traditionally, in the cigarettes industry, the determination of ammonium ion in the mainstream smoke is performed by ion chromatography. This work studies this determination and compares the results of this technique with the use of external and internal standard calibration. A reference cigarette sample presented measurement uncertainty of 2.0 μg/cigarette and 1.5 μg/cigarette, with external and internal standard, respectively. It is observed that the greatest source of uncertainty is the bias correction factor and that it is even more significant when using external standard, confirming thus the importance of internal standardization for this correction.

Cromatografia gasosa ultrarrápida: uma visão geral sobre parâmetros, instrumentação e aplicações

Since the introduction of GC there has been an ongoing interest in reducing time of analysis resulting in new terms and definitions such as ultra fast gas chromatography (UF-GC). One of the most used definitions describes UF-GC as a technique that combines the employment of short narrow bore column with very fast temperature programming rates producing chromatographic peaks in the range of 50 ms and allowing separations times in 1-2 min or less. This paper summarizes the analytical approaches, the main parameters involved and the instrumentation towards UF-GC.

Desenvolvimento de um algoritmo para identificação e correção de spikes em espectroscopia Raman de imagem

Raman imaging spectroscopy is a highly useful analytical tool that provides spatial and spectral information on a sample. However, CCD detectors used in dispersive instruments present the drawback of being sensitive to cosmic rays, giving rise to spikes in Raman spectra. Spikes influence variance structures and must be removed prior to the use of multivariate techniques. A new algorithm for correction of spikes in Raman imaging was developed using an approach based on comparison of nearest neighbor pixels. The algorithm showed characteristics including simplicity, rapidity, selectivity and high quality in spike removal from hyperspectral images.

Utilização de detecção por espalhamento de luz evaporativo para a análise de produtos naturais

The interest in the use of evaporative light scattering detector (ELSD) for the analysis of different classes of natural products has grown over the years. This is because this detector has become an excellent alternative compared to other types of detectors, such as the refractive index detector and the ultraviolet (UV) detector. This review describes the basic principles of ELSD functioning and discusses the advantages and disadvantages in using an ELSD for the analysis of organic compounds. Additionaly, an overview, covering the last 23 years, of ELSD applications in natural products analysis (saponins, terpenes, carbohydrates, glycosides, alkaloids, steroids, flavonoids, peptides, polyketides, coumarins and iridoids) is presented and discussed.

Efeitos das condições ambientais sobre o teor e variabilidade dos óleos voláteis de dalbergia frutescens (Vell.) Britton (Fabaceae)

The volatile oils of Dalbergia frutescens were obtained by hydrodistillation on a Clevenger-modified apparatus for every month of one year and assessed on GC/MS and GC/FID detectors for qualitative and quantitative analyses. The influence on content of volatile oils was directly proportional to the environmental variables, temperature and cloudiness, and inversely proportional to precipitation. Among the volatile compounds detected, linalool, β-damascenone, α-ionone, geranyl acetone and β-ionone were the main components, of which β-damascenone and β-ionone were found at the highest concentrations.

Defects in Persistent Luminescence Materials

Persistent luminescence materials can store energy from solar radiation or artificial lighting and release it over a period of several hours without a continuous excitation source. These materials are widely used to improve human safety in emergency and traffic signalization. They can also be utilized in novel applications including solar cells, medical diagnostics, radiation detectors and structural damage sensors. The development of these materials is currently based on methods based on trial and error. The tailoring of new materials is also hindered by the lack of knowledge on the role of their intrinsic and extrinsic lattice defects in the appropriate mechanisms. The goal of this work was to clarify the persistent luminescence mechanisms by combining ab initio density functional theory (DFT) calculations with selected experimental methods. The DFT approach enables a full control of both the nature of the defects and their locations in the host lattice. The materials studied in the present work, the distrontium magnesium disilicate (Sr₂MgSi₂O₇) and strontium aluminate (SrAl₂O₄) are among the most efficient persistent luminescence hosts when doped with divalent europium Eu²⁺ and co-doped with trivalent rare earth ions R³⁺ (R: Y, La-Nd, Sm, Gd-Lu). The polycrystalline materials were prepared with the solid state method and their structural and phase purity was confirmed by X-ray powder diffraction. Their local crystal structure was studied by high-resolution transmission electron microscopy. The crystal and electronic structure of the nondoped as well as Eu²⁺, R^2+/3+ and other defect containing materials were studied using DFT calculations. The experimental trap depths were obtained using thermoluminescence (TL) spectroscopy. The emission and excitation of Sr₂MgSi₂O₇:Eu²+,Dy³⁺ were also studied. Significant modifications in the local crystal structure due to the Eu²⁺ ion and lattice defects were found by the experimental and DFT methods. The charge compensation effects induced by the R³⁺ co-doping further increased the number of defects and distortions in the host lattice. As for the electronic structure of Sr₂MgSi₂O₇ and SrAl₂O₄, the experimental band gap energy of the host materials was well reproduced by the calculations. The DFT calculated Eu²⁺ and R^2+/3+ 4fn as well as 4f^n-15d¹ ground states in the Sr₂MgSi₂O₇ band structure provide an independent verification for an empirical model which is constructed using rather sparse experimental data for the R³⁺ and especially the R²⁺ ions. The intrinsic and defect induced electron traps were found to act together as energy storage sites contributing to the materials’ efficient persistent luminescence. The calculated trap energy range agreed with the trap structure of Sr₂MgSi₂O₇ obtained using TL measurements. More experimental studies should be carried out for SrAl₂O₄ to compare with the DFT calculations. The calculated and experimental results show that the electron traps created by both the rare earth ions and vacancies are modified due to the defect aggregation and charge compensation effects. The relationships between this modification and the energy storage properties of the solid state materials are discussed.

Reaktorisydämen valvontajärjestelmän modernisointi Olkiluodon kiehutusvesilaitoksella

Reaktorisydämen valvonnalla varmistetaan, että polttoaineelta vaaditut termiset marginaalit toteutuvat ja polttoaineen suojakuori säilyy ehjänä. Olkiluodon kiehutusvesilaitoksen nykyinen sydämen valvontajärjestelmä koostuu SIMULATE-3-sydänsimulaattoriohjelmasta, reaktorisydämen instrumentoinnista, termisen tehon laskentaohjelmasta, tiedonkeruuohjelmista ja käynnistysautomatiikasta. Uusi järjestelmä koostuu näiden lisäksi GARDEL-ohjelmasta, joka on kehitetty kevytvesireaktoreiden sydämen käytön suunnitteluun ja valvontaan. GARDEL käyttää laskentaan samoja ohjelmia, jotka ovat jo Olkiluodon kiehutusvesilaitoksella käytössä. Tämän työn tarkoituksena oli verrata nykyistä ja uutta sydämen valvontajärjestelmää Olkiluodon kiehutusvesilaitoksella. Työssä tutkittiin LPRM-detektorien kalibroinnin jälkeisen datan käsittelyä, palamapäivitystä, stabiilisuuslaskentaa ja adaptiivisia menetelmiä. Järjestelmien vertailuun käytettiin Olkiluoto 2 -laitosyksiköltä käyttöjaksolta 31 (2011–2012) saatuja laskentuloksia. Tulosten perusteella havaittiin uuden järjestelmän laskennassa yksittäisiä virheitä, jotka tulee korjata. Lisäksi uuden järjestelmän toiminnasta tarvitaan lisäselvitystä.

Suorakulmaisten palonrajoittimien valmistettavuuden kehittäminen

Palonrajoittimet ovat tuotteita, jotka estävät tulen ja savun leviämisen palo-osastosta toiseen ja mahdollistavat ihmisten turvallisen ulospääsyn palotilanteessa. Tämän diplomityön tavoitteena oli vähentää suorakulmaisten palonrajoittimien valmistuskustannuksia niiden valmistettavuutta kehittämällä. Työn teoriaosassa käsitellään valmistettavuutta ja kokoonpantavuutta kehittäviä menetelmiä DFM:ää (Design for Manufacturability) ja DFA:ta (Design for Assembly) sekä palonrajoittimien ja ohutlevytuotteiden erityispiirteitä. Käytännön osuudessa esitellään tutkimusta varten valmistetut kolme kehitettävää palonrajoitinta, joita vertaillaan myös kilpaileviin tuotteisiin. Tuotteista analysoidaan osamääriä, materiaalikustannuksia ja työaikoja. Palonrajoittimien ongelmakohtia olivat muun muassa liittäminen ja kokoonpantavuus. Työssä esitetään keinoja palonrajoitinten valmistusystävälliseen suunnitteluun ja uusi moduloitu tuoteperhemalli, jolla vähennetään varsinkin valmistuksesta aiheutuvia kiinteitä kustannuksia. Lisäksi työssä esitetään alustava runkoratkaisumalli uudelle tuoteperheelle.

Tobacco experimental model to induce urinary bladder neoplasms

OBJECTIVE: to develop an experimental model of exposure to tobacco burning (cigarette) products to assess the effects of its chronic use in relation to cancers of the bladder. METHODS: the animals were chronically exposed to the burning tobacco products in a semi-open chamber to simulate smoking. Thirty young Wistar rats were divided into two groups: one with 20 animals simulating smoking for six months, and ten not exposed control animals for the same period. After exposure by inhalation of cigarette smoke, animals were euthanized and subjected to histopathological study of the bladder wall. RESULTS: no tumor was found but mild and non significant alterations. The studies of hemo-oximetry (carboxyhemoglobin and methemoglobin) and the concentration of carbon dioxide (CO2) confirm that the animals were exposed to high concentrations of tobacco smoke and its derivatives. CONCLUSION: no bladder mucosal neoplasia was found in the pathological study of animals. The developed experimental models were highly efficient, practical and easy to use and can be used in other similar studies to determine the harmful effects caused by smoking.

Study of carotid disease in patients with peripheral artery disease

Objective: To study the stenosis of the carotid arteries in patients with symptomatic peripheral arterial disease.Methods: we assessed 100 consecutive patients with symptomatic peripheral arterial disease in stages of intermittent claudication, rest pain or ulceration. Carotid stenosis was studied by echo-color-doppler, and considered significant when greater than or equal to 50%. We used univariate analysis to select potential predictors of carotid stenosis, later taken to multivariate analysis.Results: The prevalence of carotid stenosis was 84%, being significant in 40% and severe in 17%. The age range was 43-89 years (mean 69.78). Regarding gender, 61% were male and 39% female. Half of the patients had claudication and half had critical ischemia. Regarding risk factors, 86% of patients had hypertension, 66% exposure to smoke, 47% diabetes, 65% dyslipidemia, 24% coronary artery disease, 16% renal failure and 60% had family history of cardiovascular disease. In seven patients, there was a history of ischemic cerebrovascular symptoms in the carotid territory. The presence of cerebrovascular symptoms was statistically significant in influencing the degree of stenosis in the carotid arteries (p = 0.02 at overall assessment and p = 0.05 in the subgroups of significant and non-significant stenoses).Conclusion: the study of the carotid arteries by duplex scan examination is of paramount importance in the evaluation of patients with symptomatic peripheral arterial disease, and should be systematically conducted in the study of such patients.

Michelson interferometer with porch swing bearing for portable FTIR spectrometer

The interferometer for low resolution portable Fourier Transform middle infrared spectrometer was developed and studied experimentally. The final aim was a concept for a commercial prototype. Because of the portability, the interferometer should be compact sized and insensitive to the external temperature variations and mechanical vibrations. To minimise the size and manufacturing costs, Michelson interferometer based on plane mirrors and porch swing bearing was selected and no dynamic alignment system was applied. The driving motor was a linear voice coil actuator to avoid mechanical contact of the moving parts. The driving capability for low mirror driving velocities required by the photoacoustic detectors was studied. In total, four versions of such an interferometer were built and experimentally studied. The thermal stability during the external temperature variations and the alignment stability over the mirror travel were measured using the modulation depth of the wide diameter laser beam. Method for estimating the mirror tilt angle from the modulation depth was developed to take account the effect from the non-uniform intensity distribution of the laser beam. The spectrometer stability was finally studied also using the infrared radiation. The latest interferometer was assembled for the middle infrared spectrometer with spectral range from 750 cm−1 to 4500 cm−1. The interferometer size was (197 × 95 × 79) mm3 with the beam diameter of 25 mm. The alignment stability as the change of the tilt angle over the mirror travel of 3 mm was 5 μrad, which decreases the modulation depth only about 0.7 percent in infrared at 3000 cm−1. During the temperature raise, the modulation depth at 3000 cm−1 changed about 1 . . . 2 percentage units per Celsius over short term and even less than 0.2 percentage units per Celsius over the total temperature raise of 30 °C. The unapodised spectral resolution was 4 cm−1 limited by the aperture size. The best achieved signal to noise ratio was about 38 000:1 with commercially available DLaTGS detector. Although the vibration sensitivity requires still improving, the interferometer performed, as a whole, very well and could be further developed to conform all the requirements of the portable and stable spectrometer.

Simulation of new p-type pixel strip detector with enhanced multiplication effect

This Master’s Thesis is dedicated to the simulation of new p-type pixel strip detector with enhanced multiplication effect. It is done for high-energy physics experiments upgrade such as Super Large Hadron Collider especially for Compact Muon Solenoid particle track silicon detectors. These detectors are used in very harsh radiation environment and should have good radiation hardness. The device engineering technology for developing more radiation hard particle detectors is used for minimizing the radiation degradation. New detector structure with enhanced multiplication effect is proposed in this work. There are studies of electric field and electric charge distribution of conventional and new p-type detector under reverse voltage bias and irradiation. Finally, the dependence of the anode current from the applied cathode reverse voltage bias under irradiation is obtained in this Thesis. For simulation Silvaco Technology Computer Aided Design software was used. Athena was used for creation of doping profiles and device structures and Atlas was used for getting electrical characteristics of the studied devices. The program codes for this software are represented in Appendixes.

Pulmonary emphysema induced by passive smoking: an experimental study in rats

We describe a short time model for inducing experimental emphysema in rats by chronic tobacco smoke inhalation. Three groups of male Wistar rats (6 months old) were studied: controls (N = 8), rats intoxicated for 45 days (s-45, N = 7) or for 90 days (s-90, N = 8). The exposed animals were intoxicated 3 times a day (10 cigarettes per exposure period), 5 days a week. Pulmonary damage was assessed by means of functional tests and quantitative pathological examination of the airways and lung parenchyma. The s-45 and s-90 animals were similar in terms of functional residual capacity (FRC) corrected for body weight (FRC/kg) but both groups of smoking rats exhibited significantly higher FRC/kg values than the controls (s-45 = 6.33; s-90 = 6.46; controls = 3.78; P<0.05). When the two groups of smoking rats were pooled together and compared to controls, they showed decreased lung elastance (1.6 vs 2.19; P = 0.046) and increased mean linear intercept (Lm) (85.14 vs 66.44; P = 0.025). The s-90 animals presented higher inflammation and muscular hypertrophy at the level of the axial bronchus than the controls (P<0.05). When smoking groups were pooled and compared to controls, they presented significantly higher inflammation at the lateral level (P = 0.028), as well as airway secretory hyperplasia (P = 0.024) and smooth muscle hypertrophy (P = 0.005) at the axial level. Due to its simplicity, low cost and short duration, this technique may be a useful model to obtain new information about airspace remodeling due to chronic tobacco consumption