Determination of triamterene in human plasma and urine after its cloud point extraction

A new analytical approach was developed involving cloud point extraction (CPE) and spectrofluorimetric determination of triamterene (TM) in biological fluids. A urine or plasma sample was prepared and adjusted to pH 7, then TM was quickly extracted using CPE, using 0.05% (w/v) of Triton X-114 as the extractant. The main factors that affected the extraction efficiency (the pH of the sample, the Triton X-114 concentration, the addition of salt, the extraction time and temperature, and the centrifugation time and speed) were studied and optimized. The method gave calibration curves for TM with good linearities and correlation coefficients (r) higher than 0.99. The method showed good precision and accuracy, with intra- and inter-assay precisions of less than 8.50% at all concentrations. Standard addition recovery tests were carried out, and the recoveries ranged from 94.7% to 114%. The limits of detection and quantification were 3.90 and 11.7 µg L-1, respectively, for urine and 5.80 and 18.0 µg L-1, respectively, for plasma. The newly developed, environmentally friendly method was successfully used to extract and determine TM in human urine samples.

Simultaneous determination of four phenolic compounds in extracts of aerial parts of Ipomoea pes-caprae (L.) R. Br. (Convolvulaceae) by HPLC-UV

Among other applications, Ipomoea pes-caprae is popularly used to treat jellyfish stings, supporting the development of a product for dermatological use. Hydroethanolic spray-dried extract was chosen for the further development of phytomedicines, and a stability-indicative HPLC-UV method was developed and validated for the determination of isoquercitrin and isochlorogenic acids A, B and C. The method was developed using a C18 column (250 x 4.6 mm, 5 µm) with an acetonitrile:water mobile phase at pH 3.0 in a gradient run. The four constituents and other unidentified components of the extract were appropriately resolved without interference of degradation products after stress tests (acid, alkali, neutral, oxidant, photolysis). The method showed linearity in the isoquercitrin concentration range from 5.0-50.0 µg mL-1, with adequate precision (RSD% < 2.5% for the intra- and inter-day studies), accuracy (recovery of 100.0 ± 2.0%), and robustness. Both the herbal drug and spray-dried extract of I. pes-caprae were subjected to stability studies in accelerated and long-term conditions over four months. The samples maintained their characteristics and marker contents (< 10% of variation).

AVALIAÇÃO DE MÉTODOS DE SOLUBILIZAÇÃO PARA DETERMINAÇÃO DE METAIS EM GLICERINA PROVENIENTE DA PRODUÇÃO DE BIODIESEL POR TÉCNICAS DE ESPECTROMETRIA ATÔMICA

This paper describes the evaluation of simple and fast solubilization methods for the determination of Ca, Mg, and K in glycerin samples from biodiesel production by atomic spectrometry. The solubilization in water was compared with two other methods: solubilization in formic acid and solubilization in ethanol. Using solubilization in water, determination of the three analytes was possible; the values of limits of detection for Ca, K, Mg were 0.31, 0.06, and 0.16 mg kg−1, respectively. Because no adequate reference material was available, the accuracy was evaluated by assessing the recoveries tests with both solubilization methods; the evaluation ranged from 90% to 115%, with values of relative standard deviation >8%, indicating good accuracy of the measure. Four crude glycerin samples obtained from biodiesel plants of Rio Grande do Sul were analyzed after treatment with the different methods of solubilization, and the obtained results of Ca, Mg, and K concentration were in agreement with the values obtained from both solubilization methods. Therefore, solubilization in water is concluded to be a simpler, faster, and viable method for sample preparation of glycerin.

DETERMINAÇÃO DE Cd E Pb EM AMOSTRAS DE GOMA XANTANA POR GF AAS

This paper describes the evaluation of a method for determination of Cd and Pb in xanthan gum samples by Graphite Furnace Atomic Absorption Spectrometry (GF AAS) using NH4H2PO4 as the chemical modifier. The sample preparation was performed using a reflux system adapted in the digestion tubes. With this system it was possible to increase the temperature of the digester block above the boiling point of the reaction medium, preventing loss of analyte and excessive evaporation of acids during heating. Samples were digested with HNO3 for 3 h in a digester block at 220 ºC. The limits of detection for Cd and Pb were 2.2 and 33.8 ng g-1, respectively. The RSDs for both analytes were, on average, lower than 5.0% and accuracy was verified by recovery tests, yielding values in the 83-100% range.

Sensitive bromatometric assay methods for finasteride in pharmaceuticals

Three sensitive spectrophotometric methods are presented for the determination of finasteride in bulk and in tablets. The methods rely on the use of bromate-bromide reagent and three dyes namely, methyl orange, indigocarmine and thymol blue as reagents. They involve the addition of a measured excess of bromate-bromide reagent to finasteride in acid medium, and after the bromination reaction is judged to be complete, the unreacted bromine is determined by reacting with a fixed amount of either methylorange and measuring the absorbance at 520 nm (method A) or indigocarmine and measuring the absorbance at 610 nm (method B) or thymol blue and measuring the absorbance at 550 nm (method C). In all the methods, the amount of insitu generated bromine reacted corresponds to the amount of finasteride. The absorbance measured at the respective wavelength is found increase linearly with the concentration of finasteride. Beer's law is obeyed in the ranges 0.25- 2.0, 0.5-6.0 and 1-12 µg mL-1 for method A, method B and method C, respectively. The calculated molar absorptivity values are 5.7x10(4), 3.12x10(4) and 1.77x10(4) L mol-1 cm-1 respectively, for method A, method B and method C, and the corresponding Sandell sensitivity values are 0.0065, 0.012 and 0.021 µg cm-2. The limits of detection (LOD) and quantification (LOQ) are also reported for all the methods. Accuracy and, intra-day and inter-day precisions of the methods were established according to the current ICH guidelines. The methods were successfully applied to the determination of finasteride in commercially available tablets and the results were found to closely agree with the label claim. The results of the methods were statistically compared with those of a reference method by applying Student's t-test and F-test. The accuracy and reliability of the methods were further confirmed by performing recovery tests via standard addition procedure.

Argentimetric assay of ranitidine in bulk drug and in dosage forms

Two simple, rapid and cost-effective methods based on titrimetric and spectrophotometric techniques are described for the assay of RNH in bulk drug and in dosage forms using silver nitrate, mercury(II)thiocyanate and iron(III)nitrate as reagents. In titrimetry, an aqueous solution of RNH is treated with measured excess of silver nitrate in HNO3 medium, followed by determination of unreacted silver nitrate by Volhard method using iron(III) alum indicator. Spectrophotometric method involve the addition a known excess of mercury(II)thiocyanate and iron(III)nitrate to RNH, followed by the measurement of the absorbance of iron(III)thiocyante complex at 470 nm. Titrimetric method is applicable over 4-30 mg range and the reaction stoichiometry is found to be 1:1 (RNH: AgNO3). In the spectrophotometric method, the absorbance is found to increase linearly with concentration of RNH which is corroborated by the correlation coefficient of 0.9959. The system obey Beer's law for 5-70 µg mL-1. The calculated apparent molar absorptivity and sandell sensitivity values are found to be 3.27 ´ 10³ L mol-1 cm-1, 0.107 µg cm-2 respectively. The limits of detection and quantification are also reported for the spectrophotometric method. Intra-day and inter-day precision and accuracy of the methods were evaluated as per ICH guidelines. The methods were successfully applied to the assay of RNH in formulations and the results were compared with those of a reference method by applying Student's t and F-tests. No interference was observed from common pharmaceutical excipients. The accuracy of the methods was further ascertained by performing recovery tests by standard addition method.

Nollapistekiinnittimen hyödyntäminen työkalun valmistuksessa ja muovausprosessissa

Tämä diplomityö tehtiin Lappeenrannan teknillisen yliopiston konetekniikan osastolle. Työn tavoitteena oli kartoittaa nollapistekiinnittimien tyyppejä ja toimintaperiaatteita sekä luoda muistilista liittyen nollapistekiinnittimen käyttöönottoon kiinnitysratkaisuna. Nollapistekiinnitin on konepajatekniikan kappaleenkiinnitin, joka tarjoaa tarkan paikoituksen, nopean asetusajan ja yksinkertaisen kappaleenvaihdon. Työssä tutkitaan nollapistekiinnittimien ominaisuuksia ja käyttökohteita, esitellään erityyppisiä nollapistekiinnittimiä ja vertaillaan niitä perinteisiin kiinnitysmenetelmiin. Työn kokeellisen osuuden tavoite oli tutkia nollapistekiinnittimen ominaisuuksia ja toimintaa ja pohtia mahdollisuuksia muovaustyökalun valmistuksessa ja kiinnittämisessä muovauspuristimeen. Kokeet tehtiin LTY:n konepajatekniikan laboratoriossa kesä- ja heinäkuussa 2010.

Monitoring of centrifugal pump operation by a frequency converter

Centrifugal pumps are widely used in industrial and municipal applications, and they are an important end-use application of electric energy. However, in many cases centrifugal pumps operate with a significantly lower energy efficiency than they actually could, which typically has an increasing effect on the pump energy consumption and the resulting energy costs. Typical reasons for this are the incorrect dimensioning of the pumping system components and inefficiency of the applied pump control method. Besides the increase in energy costs, an inefficient operation may increase the risk of a pump failure and thereby the maintenance costs. In the worst case, a pump failure may lead to a process shutdown accruing additional costs. Nowadays, centrifugal pumps are often controlled by adjusting their rotational speed, which affects the resulting flow rate and output pressure of the pumped fluid. Typically, the speed control is realised with a frequency converter that allows the control of the rotational speed of an induction motor. Since a frequency converter can estimate the motor rotational speed and shaft torque without external measurement sensors on the motor shaft, it also allows the development and use of sensorless methods for the estimation of the pump operation. Still today, the monitoring of pump operation is based on additional measurements and visual check-ups, which may not be applicable to determine the energy efficiency of the pump operation. This doctoral thesis concentrates on the methods that allow the use of a frequency converter as a monitoring and analysis device for a centrifugal pump. Firstly, the determination of energy-efficiency- and reliability-based limits for the recommendable operating region of a variable-speed-driven centrifugal pump is discussed with a case study for the laboratory pumping system. Then, three model-based estimation methods for the pump operating location are studied, and their accuracy is determined by laboratory tests. In addition, a novel method to detect the occurrence of cavitation or flow recirculation in a centrifugal pump by a frequency converter is introduced. Its sensitivity compared with known cavitation detection methods is evaluated, and its applicability is verified by laboratory measurements for three different pumps and by using two different frequency converters. The main focus of this thesis is on the radial flow end-suction centrifugal pumps, but the studied methods can also be feasible with mixed and axial flow centrifugal pumps, if allowed by their characteristics.

Accuracy and efficiency evaluation of point-centered quarter method variations for vegetation sampling in an araucaria forest

In order to verify Point-Centered Quarter Method (PCQM) accuracy and efficiency, using different numbers of individuals by per sampled area, in 28 quarter points in an Araucaria forest, southern Paraná, Brazil. Three variations of the PCQM were used for comparison associated to the number of sampled individual trees: standard PCQM (SD-PCQM), with four sampled individuals by point (one in each quarter), second measured (VAR1-PCQM), with eight sampled individuals by point (two in each quarter), and third measuring (VAR2-PCQM), with 16 sampled individuals by points (four in each quarter). Thirty-one species of trees were recorded by the SD-PCQM method, 48 by VAR1-PCQM and 60 by VAR2-PCQM. The level of exhaustiveness of the vegetation census and diversity index showed an increasing number of individuals considered by quadrant, indicating that VAR2-PCQM was the most accurate and efficient method when compared with VAR1-PCQM and SD-PCQM.

Sähköauto osana älykästä sähköverkkoa – Ohjaus ja toiminnallisuudet

Tulevaisuudessa sähköverkko kohtaa monia haasteita, kun sähköautot yleistyvät, vaatien suuren tehotarpeen. Uusiutuvan energiantuotannon epävarma huipputehon tuotanto ei välttämättä pysty kattamaan sähköautoista johtuvaa suurta tehopiikkiä, jos suuret määrät ajoneuvoista kytketään yhtä aikaa lataukseen. Jos sähköajoneuvot voidaan ladata ohjatusti, ei välttämättä tarvita lisäenergian tuotantoa kattamaan kasvanutta huipputehon tarvetta. Lisäksi sähköajoneuvojen akut toimivat koko sähköverkolle energiavarastoina, jollaista ei ole ennen ollut. Älykkäällä sähköverkolla voidaan ohjata sähköajoneuvon latausta, mikäli ajoneuvossa on ohjausjärjestelmä ja akkujen varaustilan mittaus. Tässä kandidaatin työssä ohjelmoidaan mittaus- ja ohjauskortti plug-in hybridiautoa varten, jossa on V2G-ominaisuus. Ohjainkortista toteutetaan toimintakuvaus, jonka mukaan se myös ohjelmoidaan. Ohjainkortti mittaa akkujen jännitettä ja virtaa, joista voidaan määrittää akkujen varaustilat. Ohjainkortti lähettää tiedot eteenpäin PC:lle, jolta ohjainkortti saa käskyn toimintatilasta. Mittaustietojen perusteella voidaan seurata mahdollisia vikatilanteita. Kandidaatintyön aikana ohjainkorttia ei ehditty asentamaan ajoneuvoon, mutta laboratoriotestien mukaan voidaan todeta, että ohjainkortti on ohjelmallisesti toimiva. Mittauksissa selvisi, että ohjainkortin mittaustulot eivät olleet tarpeeksi tarkkoja käyttökohteeseen. Todettiin, että ohjainkortti vaatii rakenteellisia muutoksia mittaustuloksien parantamista varten, ennen ohjainkortin käyttöönottoa, mutta kandidaatintyön tavoitteet saavutettiin.

Epälineaaristen regressiomenetelmien vertaaminen robottikäden otemallinnuksessa

Tässä työssä verrattiin monikerrosperseptronin, radiaalikantafunktioverkon, tukivektoriregression ja relevanssivektoriregression soveltuvuutta robottikäden otemallinnukseen. Menetelmille ohjelmoitiin koeympäristö Matlabiin, jossa mallit koestettiin kolmiulotteisella kappaledatalla. Koejärjestely sisälsi kaksi vaihetta. Kokeiden ensimmäisessä vaiheessa menetelmille haettiin sopivat parametrit ja toisessa vaiheessa menetelmät koestettiin. Kokeilla kerättiin dataa menetelmien keskinäiseen vertailuun. Vertailussa huomioitiin laskentanopeus, koulutusaika ja tarkkuus. Tukivektoriregressio löydettiin potentiaaliseksi vaihtoehdoksi mallintamiseen. Tukivektoriregression koetuloksia analysoitiin muita menetelmiä enemmän hyvien koetulosten takia.

Dry months in the agricultural region of Ribeirão Preto, state of São Paulo-Brazil: an study based on the extreme value theory

The application of the Extreme Value Theory (EVT) to model the probability of occurrence of extreme low Standardized Precipitation Index (SPI) values leads to an increase of the knowledge related to the occurrence of extreme dry months. This sort of analysis can be carried out by means of two approaches: the block maxima (BM; associated with the General Extreme Value distribution) and the peaks-over-threshold (POT; associated with the Generalized Pareto distribution). Each of these procedures has its own advantages and drawbacks. Thus, the main goal of this study is to compare the performance of BM and POT in characterizing the probability of occurrence of extreme dry SPI values obtained from the weather station of Ribeirão Preto-SP (1937-2012). According to the goodness-of-fit tests, both BM and POT can be used to assess the probability of occurrence of the aforementioned extreme dry SPI monthly values. However, the scalar measures of accuracy and the return level plots indicate that POT provides the best fit distribution. The study also indicated that the uncertainties in the parameters estimates of a probabilistic model should be taken into account when the probability associated with a severe/extreme dry event is under analysis.

Static tests of constructive tires using hydraulic press on the soil

ABSTRACT The power consumption and load capacity of agricultural machines have grown and the effects of pressure on the soil by tires have been still little investigated. In concern with sustainable development, the relationship machine-tire-soil must be in balance to give more consistency on the best use of tires for a given load. This study aimed to evaluate four tires of two constructive types, the bias belted tires and radial tires, both with respective rim diameters of 22.5 and 26.5 inches with variables measuring the footprint, elastic deformation, sinkage and resistance to penetration. A hydraulic press with an attachment shaft for tire mounting and a box of soil in which the tire has been imposed on a load of 53.00 kN using nominal pressures recommended by the tire manufacturer. The radial construction tire with rim diameter of 26.5 inches obtained less sinkage and resistance to penetration; however, greater elastic deformation and footprint compared to other tires. The bias-belted tire with 22.5-inch rim presented the highest resistance to penetration and the lowest elastic deformation.

Servo drive in hoist application

The objective of this master thesis is to test according to hoisting requirements, a servo drive system and compare its performance with the performance of a drive equipped with a vector controlled frequency converter. Both systems utilize closed-loop vector control based on PCL program control. In order to compare the results of tests both systems were connected to the same motor driving a variable speed electrical chain hoist. Tests were based on requirements to both systems. As requirements of tests zero speed operation, operation in field weakening, positioning accuracy and smoothness of motion are taken into consideration. Both systems demonstrate quite similar performance and meet the requirements. Servo drive system demonstrates a high positioning accuracy and dynamic performance. Frequency converter is not able to provide the same positioning accuracy and dynamic performance as servo drive.