Flotation for cell recovery from small volumes of yeast cultures

Flotation or cell recovery in foams (proportion of the total cells in the medium transferred to the foam) and flotation efficiency (proportion of the cells transferred from an initial volume of medium equal to the residual volume after flotation) are functions of time, aeration rate, initial volume of medium, and initial concentration of cells. Cell recovery reached constant values (around 96.4 +/- 6.3%) and flotation efficiency decreased (owing to increases in the liquid content of the foam), with increases in air how rate (above 6-7 ml air s(-1)) and volumes of medium (above 11 ml) added to the column. Increases in concentration of cells in the medium led to increases in the concentration of cells in the foam.

Determination of acetaldehyde in fuel ethanol by high-performance liquid chromatography with electrochemical detection

The cyclic voltammetric behavior of acetaldehyde and the derivatized product with 2,4-dinitrophenylhydrazine (DNPHi) has been studied at a glassy carbon electrode. This study was used to optimize the best experimental conditions for its determination by high-performance liquid chromatographic (HPLC) separation coupled with electrochemical detection. The acetaldehyde-2,4-dinitrophenyl.hydrazone (ADNPH) was eluted and separated by a reversed-phase column, C-18, under isocratic conditions with the mobile phase containing a binary mixture of methanol/LiCl(aq) at a concentration of 1.0 x 10(-3) M (80:20 v/v) and a flow rate of 1.0 mL min(-1). The optimum condition for the electrochemical detection of ADNPH was +1.0 V vs. Ag/AgCl as a reference electrode. The proposed method was simple, rapid (analysis time 7 min) and sensitive (detection limit 3.80 mu g L-1) at a signal-to-noise ratio of 3:1. It was also highly selective and reproducible [standard deviation 8.2% +/- 0.36 (n = 5)]. The analytical curve of ADNPH was linear over the range of 3-300 mg L-1 per injection (20 mu L), and the analytical recovery was > 99%.

Treatment of urinary stress incontinence by intravaginal electrical stimulation and pelvic floor physiotherapy

Treatment of urinary stress incontinence (USI) by intravaginal electrical stimulation (IES) and pelvic floor physiotherapy represents an alternative to other therapies. The purpose of this work was to evaluate the effectiveness of this treatment inpatients with urinary incontinence. From January 1998 to May 2000, 30 women (mean age 54 years) were studied. All patients had USI and 70% urge incontinence; average follow-up was 7 months. Selection criteria were based on clinical history, objective evaluation of perineal musculature by perineometry, and urodynamics. The treatment protocol consisted of three sessions of IES per week for 14 weeks using INNOVA equipment. Physiotherapy was initiated in the fifth week of IES. A significant decrease in the number of micturitions and urgency was observed after treatment (P<0.01). The pad test showed a reduction in urinary leakage from 13.9 to 5.9 g after treatment (P<0.01). Objective evaluation of perineal muscle strength showed a significant improvement in all patients after treatment (P<0.01). A positive correlation was observed between maximum flow rate (Q(max)) and all three variables: urethral pressure profile at rest and on straining (stop test), and abdominal leak-point pressure (ALPP). A positive correlation was also observed between ALPP and the stop test. Over 100 different surgical and conservative treatments have been tried to manage USI. The majority of these procedures reveal that despite progress already made in this area, there is no ideal treatment. Satisfactory results can be achieved with this method, especially with patients who are reluctant to undergo surgery because of personal or clinical problems.

Determination of aldehydes and ketones in fuel ethanol by high-performance liquid chromatography with electrochemical detection

A new methodology was developed for analysis of aldehydes and ketones in fuel ethanol by high-performance liquid chromatography (HPLC) coupled to electrochemical detection. The electrochemical oxidation of 5-hydroxymetkylfurfural, 2-furfuraldehyde, butyraldehyde, acetone and methyl ethyl ketone derivatized with 2,4-dinitrophenylhydrazine (DNPH) at glassy carbon electrode present a well defined wave at +0.94 V; +0.99 V; +1.29 V; +1.15 V and +1.18 V, respectively which are the basis for its determination on electrochemical defector. The carbonyl compounds derivatized were separated by a reverse-phase column under isocratic conditions with a mobile phase containing a binary mixture of methanol /LiClO4(aq) at a concentration of 1.0 x 10(-3) mol L-1 (80:20 v/v) and a flow-rate of 1.1 mL min(-1). The optimum potential for the electrochemical detection of aldehydes-DNPH and ketones-DNPH was +1.0 V vs. Ag/AgCl. The analytical curve of aldehydes-DNPH and ketones-DNPH presented linearity over the range 5.0 to 400.0 ng mL(-1), with detection limits of 1.7 to 2.0 ng mL(-1) and quantification limits from 5.0 to 6.2 ng mL(-1), using injection volume of 20 mu L. The proposed methodology was simple, low time-consuming (15 min/analysis) and presented analytical recovery higher than 95%.

Plasma enhanced chemical vapor deposition of titanium(IV) ethoxide-oxygen-helium mixtures

Thin films were deposited by plasma enhanced chemical vapor deposition from titanium (IV) ethoxide (TEOT)-oxygen-helium mixtures. Actinometric optical emission spectroscopy was used to obtain the relative plasma concentrations of the species H, CH, O and CO as a function of the percentage of oxygen in the feed, R(ox). The concentrations of these species rise with increasing R(ox) and tend to fall for R(ox) greater than about 45%. As revealed by a strong decline in the emission intensity of the actinometer Ar as R(ox) was increased, the electron mean energy or density (or both) decreased as greater proportions of oxygen were fed to the chamber. This must tend to reduce gas-phase fragmentation of the monomer by plasma electrons. As the TEOT flow rate was fixed, however, and since the species H and CH do not contain oxygen, the rise in their plasma concentrations with increasing R(ox) is explained only by intermediate reactions involving oxygen or oxygen-containing species. Transmission infrared (IRS) and X-ray photoelectron (XPS) spectroscopies were employed to investigate film structure and composition. The presence of CH(2), CH(3), C=C, C-O and C=O groups was revealed by IRS. In addition, the presence of C-O and C=O groups was confirmed by XPS, which also revealed titanium in the +4 valence state. The Ti content of the films, however, was found to be much less than that of the monomer material itself. (C) 2007 Elsevier B.V. All rights reserved.

ASSESSMENT of POLYATOMIC INTERFERENCES ELIMINATION USING A COLLISION REACTION INTERFACE (CRI) FOR INORGANIC ANALYSIS of FUEL ETHANOL BY ICP-QMS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Experimental Basis and New Insights for Cell Therapy in Chronic Obstructive Pulmonary Disease

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

INFLUENCE of THE EVAPORATOR POSITION IN STATIC DOMESTIC REFRIGERATORS

The temperature and velocity distributions of the air inside the cabinet of domestic refrigerators affect the quality of food products. If the consumer knows the location of warm and cold zones in the refrigerator, the products can be placed in the right zone. In addition, the knowledge of the thickness of thermal and hydrodynamic boundary layers near the evaporator and the other walls is also important. If the product is too close to the evaporator wall, freezing can occur, and if it is too close to warm walls, the products can be deteriorated. The aim of the present work is to develop a steady state computational fluid dynamics (CFD) model for domestic refrigerators working on natural convection regime. The Finite Volume Methodology is chosen as numerical procedure for discretizing the governing equations. The SIMPLE-Semi-Implicit Method for Pressure-Linked Equations algorithm applied to a staggered mesh was used for solving the pressure-velocity coupling problem. The Power-Law scheme is employed as interpolation function for the convective-diffusive terms, and the TDMA-Tri-Diagonal Matrix Algorithm is used to solve the systems of algebraic equations. The model is applied to a commercial static refrigerator, where the cabinet is considered an empty three-dimensional rectangular cavity with one drawer at the bottom of the cabinet, but without shelves. In order to analyze the velocity and temperature fields of the air flow inside the cabinet the evaporator temperature, Te, was varied from -20 degrees C to 0 degrees C, and nine different evaporator positions are evaluated for evaporator temperature of -15 degrees C. The cooling capacity of the evaporator for the steady state regime is also computed for each case. One can conclude that the vertical positioning of the evaporator inside the cabinet plays an important role on the temperature distribution inside the cabinet.

A Validated Stability-Indicating LC Method for Orbifloxacin in the Presence of Degradation Products

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Direct analysis of biodiesel microemulsions using an inductively coupled plasma mass spectrometry

An analytical procedure for direct introduction of biodiesel samples into an inductively coupled plasma mass spectrometer (ICP-MS) by using microemulsion for sample preparation was developed here. Cadmium, Co, Cu, Mn, Ni, Pb, Ti, and Zn were determined in biodiesel microemulsified samples prepared from different oleaginous sources (African palm, castor beans, palm, soybeans and an unknown oleaginous). Microemulsions were prepared using 0.25 mL Triton X-100, 0.25 mL 20% v v(-1) HNO(3), 0.50 mL biodiesel sample and 4.0 mL n-propanol. Argon-oxygen mixture was added to the plasma as auxiliary gas for correcting matrix effects caused by the high carbon load due to biodiesel microemulsions. The oxygen gas flow rate was set in 37.5 mL min(-1). The accuracy of the developed procedure was evaluated by applying addition-recovery experiments for biodiesel samples from different sources. Recoveries varied from 76.5 to 116.2% for all analytes but Zn in castor beans biodiesel sample (65.0 to 76.2%). Recoveries lower than 86.6% were obtained for palm biodiesel sample, probably due to matrix effects. Detection limits calculated by using oxygen in the composition of the auxiliary gas added to the plasma were higher than those calculated without using it, probably due to the highest formation of oxides. Despite oxides formation, best analytical performance was reached by using oxygen as auxiliary gas and by proper correction of transport interferences. The developed procedure based on microemulsion formation was suitable for direct introduction of biodiesel samples in ICP-MS. (C) 2010 Elsevier B.V. All rights reserved.

Pore size evolution during sintering of ceramic oxides

This paper reviews the influence of particle size distribution, agglomerates, rearrangement, sintering atmospheres and impurities on the pore evolution of some commonly studied oxides. These factors largely affect sintering mechanisms due to modifications of diffusion coefficients or evaporation-condensation. Very broad particle size distribution leads to grain growth and agglomerates densify first. Rearrangement of particles due to neck asymmetry mainly in the early stage of sintering is responsible for a high rate of densification in the first minutes of sintering by collapse of large pores. Sintering atmospheres play an important role in both densification and pore evolution. The chemical interaction of water molecules with several oxides like MgO, ZnO and SnO2 largely affects surface diffusion. As a consequence, there is an increase in the rates of pore growth and densification for MgO and ZnO and in the rate of pore growth for SnO2. Carbon dioxide does not affect the rate of sintering of MgO but greatly affects both rates of pore growth and densification of ZnO. Oxygen concentration in the atmosphere can especially affect semiconductor oxides but significantly affects the rate of pore growth of SnO2. Impurities like chlorine ions increase the rate of pore growth in MgO due to evaporation of HCl and Mg(OH)Cl, increasing the rate of densification and particle cuboidization. CuO promotes densification in SnO2, and is more effective in dry air. The rate of densification decrease and pore widening are promoted in argon. An inert atmosphere favors SnO2 evaporation due to reduction of CuO. © 1990.

CELULOSE FIBROSA DO BAGACO DA CANA-DE-ACUCAR - AVALIACAO DA ACAO AGLUTINANTE/DESAGREGANTE EM COMPRIMIDOS CONTENDO FARMACO HIDROSSOLUVEL

In this work, a fibrous cellulose obtained from the sugar cane bagasse was analysed about its binder/disintegrating action and about its interference degree in the dissolution rate ('in vitro') of active principles, when incorporated in a compact system that has a water-soluble drug. It was used as reference drug the Lithium Carbonate, considering its solubility in water and it difficulties in the compressibility and flow rate. That cellulose was evaluated in a comparative study, involving another fibrous cellulose generally used in the tablet obtainment (Microcel 3E-200). After the experiment in methodologies of dry granulation and wet granulation, it was concluded that the analysed celluloses presents adequate binder/disintegrating efficience and they are equivalents in these aspect.

Analytical chemistry in a liquid film/droplet

The measurement of nitrogen dioxide at the parts-perbillion level is described. The experimental arrangement consists of two optical fibers placed on opposite sides of and in contact with a liquid film (14-57 μL in volume) supported on a U-shaped wire guide and two tubular conduits (one of which constitutes the means for the delivery of the liquid), light from a green (555 nm) light-emitting diode enters the liquid film, composed of Griess-Saltzman reagent. The transmitted light is measured by a referenced photodetection arrangement. Sample gas flows past the droplet at a low flow rate (typically 0.10-0.25 L/min). The response is proportional to the sampling period and the analyte concentration. The limit of detection for this nonoptimized arrangement is estimated to be <10 ppb by volume for a 5 min sample. Some unusual characteristics are observed. The initial absorbance, when most of the analyte/reaction product is still near the surface, is higher than that when the content of the droplet is fully mixed. The signal depends on the sample flow rate in a nonmonotonic fashion, first increasing and then decreasing with increasing sampling rate; the specific chemistry involved in the collection and determination of NO2 may be responsible.

Pre-concentration of Cd(II), Cr(III), Cu(II) and Ni(II) on a column packed with free carboxymethylcellulose (CMCH)

Carboxymethylcellulose packed in to a glass column was used to pre-concentrate metallic cations from aqueous solutions. The pre-concentrated metal cations are directly eluted from the column using 5.0 mL of 1.0 mol L -1 hydrochloric acid. The optimum pre-concentration conditions are given (glass column, 16 cm length, 0.80 cm i.d., stationary phase height of 12 cm, flow-rate, 1.5 mL min -1). The recuperation efficiency achieved is greater than 95%, while the enrichment factor is 10 for 50 mL of solution (0.50 mg L -1 each).

Avaliacao preliminar da utilizacao do residuo industrial de man dioca (manihot esculenta granz) como excipiente em comprimidos: Caracteristicas fisicas e de compressao

The applicability of a residue of manioc (Manihot esculenta Granz) from industrial processing as a direct compression excipient was investigated in comparison with microcrystalline cellulose (Avicel® PH 101). Physical characteristics of the powders like bulk and tap densities, particle size, flow properties (flow rate, index of compressibility and angle of repose) and agglutination were evaluated. The residue had poor performance as excipient for direct compression. However, it showed better disintegration properties than Avicel. The possibility of its use as disintegrant agent will be confirmed on future studies.