A Method for Sky-Condition Classification from Ground-Based Solar Radiation Measurements

Identification of clouds from satellite images is now a routine task. Observation of clouds from the ground, however, is still needed to acquire a complete description of cloud conditions. Among the standard meteorologicalvariables, solar radiation is the most affected by cloud cover. In this note, a method for using global and diffuse solar radiation data to classify sky conditions into several classes is suggested. A classical maximum-likelihood method is applied for clustering data. The method is applied to a series of four years of solar radiation data and human cloud observations at a site in Catalonia, Spain. With these data, the accuracy of the solar radiation method as compared with human observations is 45% when nine classes of sky conditions are to be distinguished, and it grows significantly to almost 60% when samples are classified in only five different classes. Most errors are explained by limitations in the database; therefore, further work is under way with a more suitable database

A Quantitative method for the characterization of lytic metastases of the bone from radiographic images

The aim of our study was to assess the diagnostic usefulness of the gray level parameters to distinguish osteolytic lesions using radiological images. Materials and Methods: A retrospective study was carried out. A total of 76 skeletal radiographs of osteolytic metastases and 67 radiographs of multiple myeloma were used. The cases were classified into nonflat (MM1 and OL1) and flat bones (MM2 and OL2). These radiological images were analyzed by using a computerized method. The parameters calculated were mean, standard deviation, and coefficient of variation (MGL, SDGL, and CVGL) based on gray level histogram analysis of a region-of-interest.Diagnostic utility was quantified bymeasurement of parameters on osteolyticmetastases andmultiplemyeloma, yielding quantification of area under the receiver operating characteristic (ROC) curve (AUC). Results: Flat bone groups (MM2 and OL2) showed significant differences in mean values of MGL ( = 0.048) and SDGL ( = 0.003). Their corresponding values of AUC were 0.758 for MGL and 0.883 for SDGL in flat bones. In nonflat bones these gray level parameters do not show diagnostic ability. Conclusion: The gray level parametersMGL and SDGL show a good discriminatory diagnostic ability to distinguish between multiple myeloma and lytic metastases in flat bones.

Melodic Analysis of Speech Method applied to Spanish and Catalan

In this paper, we present the Melodic Analysis of Speech method (MAS) that enables us to carry out complete and objective descriptions of a language's intonation, from a phonetic (melodic) point of view as well as from a phonological point of view. It is based on the acoustic-perceptive method by Cantero (2002), which has already been used in research on prosody in different languages. In this case, we present the results of its application in Spanish and Catalan.

A simple and rapid method for urinary acetone analysis by headspace/gas chromatography

Urinalysis of acetone is important to monitor workers occupationally exposed to acetone and/or isopropanol, as well as in diagnosis of some diseases related to lipid metabolism impairment. This work shows a sensitive, simple and rapid static headspace-gas chromatographic procedure for quantitative determination of acetone in urine. The method was applied to measure acetone in 207 samples from general population volunteers, resulting in a mean level of 1.12 mg/L (± 0.47) and a range of 0.20 - 1.95 mg/L. The method is reproducible and reliable, making it suitable for routine analysis of acetone in urine.

High performance liquid chromatography method for quantification of the N-phenylpiperazine derivative LASSBio-579 in rat plasma

A rapid HPLC analytical method was developed and validated for the determination of the N-phenylpiperazine derivative LASSBio-579in plasma rat. Analyses were performed using a C18 column and elution with 20 mM sodium dihydrogen phosphate monohydrate - methanol. The analyte was monitored using a photodiode array detector (257 nm). Calibration curves in spiked plasma were linear over the concentration range of 0.3-8 mg/mL with determination coefficient > 0.99. The lower limit of quantification was 0.3 mg/mL. The applicability of the HPLC method for pharmacokinetic studies was tested using plasma samples obtained after administration of LASSBio-579 to Wistar rats, showing the specificity of the method.

Laüe back-reflection method for crystallographic orientation of a martensitic Cu-Zn-Al single crystal of the monoclinic system

A martensitic single crystal Cu-23.95Zn-3.62(wt.%)Al alloy was obtained melting pure Cu, Zn and Al using Bridgman's method. The martensitic phase (monoclinic) can present up to 24 variants, and orienting the surface according to a certain plane is a very hard task. The single crystal was submitted to 8 tons of tension (stress) along the longitudinal direction to reduce the number of variants and facilitate the surface orientation according to the desired plane. This single crystal was oriented using the Laüe back-reflection method to give surfaces with the following oriented crystallographic planes: (010), (120) and (130). It was observed that the tension stress was applied along the [010] direction.

An easy and direct method for the synthesis of 1,2,4-triazole derivatives through carboxylic acids and hydrazinophthalazine

We have developed an easy method for the synthesis of thirteen compounds derived from 1,2,4-triazoles through a carboxylic acid and hydrazinophthalazine reaction, with a 75-85% yield mediated by the use of agents such as 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide hydrochloride and 1-hydroxybenzotriazole. The operational simplicity of this method and the good yield of products make it valuable for the synthesis of new compounds with pharmacological activity.

A convenient method for lecithin purification from fresh eggs

The increasing demand for fatty acid-free lecithin required modifications in existing purification methods. In this technical note we describe a purification procedure with the following steps: a) homogenization and extraction of yolks obtained from fresh eggs with acetone, b) solubilization with ethanol and solvent elimination and c) repeated solubilization/precipitation with petroleum ether/acetone. This crude extract was chromatographed on neutral alumina, which was exhaustively washed with chloroform before elution with chloroform:methanol, allowing the sequential separation of fatty acids and lecithin. Chromatographic behavior and mass spectra of the product are presented. This fast procedure yields fatty acid-free lecithin at a competitive cost.

Quantitation of genistein and genistin in soy dry extracts by UV-Visible spectrophotometric method

This paper describes the development and validation of an UV-Visible spectrophotometric method for quantitation of genistein and genistin in soy dry extracts, after reaction with aluminum chloride. The method showed to be linear (r²= 0.9999), precise (R.S.D. < 2%), accurate (recovery of 101.56%) and robust. Seven samples of soy dry extracts were analyzed by the spectrophotometric validated method and by RP-HPLC. Genistein concentrations determined by spectrophotometry (0.63% - 16.05%) were slightly higher than values obtained by HPLC analysis (0.40% - 12.79%); however, the results of both methods showed a strong correlation.

Validation of a simple and rapid UV spectrophotometric method for dexamethasone assay in tablets

This work reports the validation of an analytical UV spectrophotometric method to assay dexamethasone in tablets (assay and dissolution studies). The method was linear in the range between 1 and 30 µg mL-1 presenting a good correlation coefficient (r = 0.9998, n = 7). Precision and accuracy analysis showed low relative standard deviation (< 2.00%) and good percentual recoveries (95-105%). The procedure was linear, accurate, precise, and robust. The method is simple, and it has low cost. It does not use polluting reagents and can be applied in dissolution studies, being an adequate alternative to assay dexamethasone in tablets.

Development and application of spectrophotometric method for the determination of cefaclor in pharmaceutical formulations

A simple, fast and sensitive spectrophotometric method for the determination of cefaclor in pharmaceutical raw and dosage forms based on reaction with ninhydrin is developed, optimized and validated. The purple color (Ruhemenn's purple) that resulted from the reaction was stabilized and measured at 560 nm. Beer's law is obeyed in the concentration range of 4-80 µg mL-1 with molar absorptivity of 1.42 × 10(5) L mole-1 cm-1. All variables including the reagent concentration, heating time, reaction temperature, color stability period, and cefaclor/ninhydrin ratio were studied in order to optimize the reaction conditions. No interference was observed from common pharmaceutical adjuvant. The developed method is easy to use, accurate and highly cost-effective for routine studies relative to HPLC and other techniques.

Rapid and accurate hplc-dad method for the determination of the herbicide bispyribac-sodium in surface water, and its validation

A new method is described for the determination of the herbicide bispyribac-sodium in surface water, especially from river and irrigated rice water samples. The method involves extraction in solid phase and quantification by high performance liquid chromatography with diode array detection (HPLC-DAD). After optimization of the extraction and separation parameters, the method was validated. The method presented average recoveries of 101.3 and 97.7%, under repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.9 to 7.5%). The method was applied for the determination of bispyribac-sodium in surface water samples with a limit of detection of 0.1 μg L-1.

Method validation and stability study of quercetin in topical emulsions

This study validated a high performance liquid chromatography (HPLC) method for the quantitative evaluation of quercetin in topical emulsions. The method was linear within 0.05 - 200 μg/mL range with a correlation coefficient of 0.9997, and without interference in the quercetin peak. The detection and quantitation limits were 18 and 29 ng/mL, respectively. The intra- and inter-assay precisions presented R.S.D. values lower than 2%. An average of 93% and 94% of quercetin was recovered for non-ionic and anionic emulsions, respectively. The raw material and anionic emulsion, but not non-ionic emulsion, were stable in all storage conditions for one year. The method reported is a fast and reliable HPLC technique useful for quercetin determination in topical emulsions.

Development of dissolution method for benznidazole tablets

The aim of this work was the development of a dissolution method for benznidazole (BNZ) tablets. Three different types of dissolution media, two stirring speeds and apparatus 2 (paddle) were used. The accomplishment of the drug dissolution profiles was compared through the dissolution efficiency. The assay was performed by spectrophotometry at 324 nm. The better conditions were: sodium chloride\hydrochloride acid buffer pH 1.2 with stirring speed of 75 rpm, volume of 900 mL and paddle as apparatus. Ahead of the results it can be concluded that the method developed consists in an efficient alternative for assays of dissolution for benznidazole tablets.

Determination of phenobarbital in human plasma by a specific liquid chromatography method: application to a bioequivalence study

A liquid chromatography method was developed and validated for the determination of phenobarbital in human plasma using phenytoin as internal standard. The drugs were extracted from plasma by liquid-liquid extraction and separated isocratically on a C12 analytical column, maintained at 35 ºC, with water:acetonitrile:methanol (58.8:15.2:26, v/v/v) as mobile phase, run at a flow rate of 1.2 mL/min with detection at 205 nm. The method was linear in the range of 0.1-4 μg/mL (r²=0.9999) and demonstrated acceptable results for the precision, accuracy and stability studies. The method was successfully applied for the bioequivalence study of two tablet formulations (test and reference) of phenobarbital 100 mg after single oral dose administration to healthy human volunteers.