Search results for "Relative"
showing 10 items of 1094 documents
Degradation study of XVIII century graffiti on the walls of Chiaramonte Palace (Palermo, Italy)
2010
A systematic investigation of the original materials and the degradation phenomena induced by soluble salts on the wall matrix and on the graffiti of the Inquisition jails of Chiaramonte Palace in Palermo (Italy) was carried out. Built in the XIV century, Chiaramonte Palace was used as Inquisition court during the XV–XVI centuries. The ancient graffiti, recently discovered, represent a unique historical witness of the prisoners that lived during that terrible period. In order to study the nature, the amount and the distribution of the salts in the masonry, stone materials sampled at different depth from the wall matrix and saline efflorescences were analysed. Different physical techniques w…
Immediate dental implants placed into infected sites present a higher risk of failure than immediate dental implants placed into non-infected sites: …
2019
Background Alveolar infection is known as a risk factor for implant failure. Current meta-analysis on the theme could not prove statistically that immediate dental implants placed into infected sites have a higher risk of failure than immediate dental implants placed into non-infected sites. The purpose of this meta-analysis was to determine the effectiveness of immediate dental implants placed into infected versus non-infected sites. Material and Methods Seven databases were sought by two reviewers. Randomized or non-randomized clinical trials that compared the placement of dental implants into infected versus non-infected sites were eligible for the study. Exclusion criteria were: papers …
Indoor air quality in schools of a highly polluted south Mediterranean area
2019
This study aimed at surveying lower secondary schools in southern Italy, in a highly polluted area. A community close to an industrial area and three villages in rural areas was investigated. Indoor temperature, relative humidity (RH), gaseous pollutants (CO 2 and NO 2 ), selected biological pollutants in indoor dust, and the indoor/outdoor mass concentration and elemental composition of PM 2.5 were ascertained. Temperature and RH were within, or close to, the comfort range, while CO 2 frequently exceeded the threshold of 1000 ppm, indicating inadequate air exchange rate. In all the classrooms, median NO 2 levels were above the WHO threshold value. Dermatophagoides p. allergen concentration…
Simplified models for the performance evaluation of desiccant wheel dehumidification
2002
In the present communication, simple models have been presented to evaluate the performance of rotary desiccant wheels based on different kind of solid desiccants e.g. silica gel and LiCl. The first part of the paper presents ‘Model 54’ which is developed for silica gel desiccant rotor. The model has been derived from the interpolation of experimental data obtained from the industry and the correlations have been developed for predicting outlet temperature and absolute humidity. The ‘Model 54’ consists of 54 coefficients corresponding to each correlation for outlet absolute humidity and temperature and it is found that the model predicts very well the performance of silica gel desiccant rot…
Determination of tea tree oil terpenes by headspace gas chromatography mass spectrometry
2016
An alternative procedure was developed for determining quality control of terpenes in tea tree oil commercial samples. The method is based on static headspace gas chromatography mass spectrometry measurements. Absolute limits of detection ranged from 1 ng for p-cymene to 71 ng for terpinen-4-ol. The accuracy of the developed methodology was evaluated by comparing the obtained eucalyptol and terpinen-4-ol concentrations with those provided for a certified sample and by comparing the developed procedure with literature tea tree oil analysis methodology. In the same way, spiked commercial samples provided recovery values ranging between 94% and 100% for all the target analytes with relative st…
Improvement of the atomic fluorescence determination of mercury by using multicommutation
2002
Atomic fluorescence spectrometry (AFS) determination of Hg has been improved by exploiting the possibilities of the multicommutation approach in order to outline a fully mechanised system which supplies the same sensitivity as the use of continuous measurements, reducing drastically the reagents consumed and waste generation. The use of multicommutation with a simultaneous reduction of the liquid–gas separator volume and the insertion point modification of argon transport gas provides a sensitivity of the AFS measurements of 300 mV ng−1 ml (using a full scale of 1000 mV), a limit of detection (3 s) of 1.3 ng l−1 and relative standard deviation values below 0.1% for 10 independent measuremen…
Preliminary Results on the Use of Leather Chrome Shavings for Air Passive Sampling
2012
A new passive sampler based on low-density polyethylene (LDPE) layflat tube filled with chrome shavings from tannery waste residues was evaluated to determine volatile organic compounds (VOCs) in indoor and outdoor areas. VOCs were directly determined by head space-gas chromatography-mass spectrometry (HS-GC-MS) without any pretreatment of the sampler and avoiding the use of solvents. Limit of detection values ranging from 20 to 75 ng sampler−1and good repeatability values were obtained for VOCs under study with relative standard deviation values from 2.8 to 9.6% except for carbon disulfide for which it was 22.5%. The effect of the amount of chrome shavings per sampler was studied and resul…
Selective determination of clenbuterol residues in urine by molecular imprinted polymer—Ion mobility spectrometry
2017
Abstract Clenbuterol is banned for sports use and strictly regulated in livestock industry. In this study, a procedure for the determination of clenbuterol residues in water and urine has been developed using selective supports combined with ion mobility spectrometry (IMS) determination. A molecular imprinted polymer (MIP) was used for efficient clean-up and preconcentration of clenbuterol followed to a dispersive liquid-liquid microextraction (DLLME) in order to improve selectivity and sensitivity of IMS determinations. Quantitative recoveries from 81 to 99% were obtained for water and spiked urine samples using MIP-DLLME-IMS method. A precision of 4.5%, established as the relative standar…
Die direkte quantitative auswertung von dünnschichtchromatogrammen durch remissions- und fluoreszenzmessungen
1971
Abstract Direct quantitative evaluation of thin-layer chromatograms by remission- and fluorescence measurements. Part 6. Determination of adrenaline, noradrenaline and dopamine from urine Adrenaline, noradrenalineand dopamine were separated from urine on aluminium oxide columns; after elution they were converted into ther O 3 ,O 4 ,N-triacetyl derivatives and separated using thin-layer chromatography. The triacetyl derivatives were in situ converted to fluorescing compounds using ethylene diamine and quantitatively estimated using the Chromatogram-Spectrophotometer (Carl Zeiss, Oberkochen). The advantage of this method over the conventional fluorometric determination of catecholamines in so…
Fast extraction methodologies for the determination of toxic arsenic in meat
2017
Summary A nonchromatographic analytical procedure has been developed for the determination of arsenic in meat samples including the major toxic arsenic species arsenite, arsenate, monomethylarsonic acid (MMA) and dimetylarsinic acid (DMA). The method is based on the extraction of arsenic species in mild conditions, selective trivalent hydride formation and final determination by hydride generation atomic fluorescence spectroscopy (HG-AFS). Different extractant agents and two different procedures, microwave-assisted extraction (MAE) and ultrasound assisted extraction at room temperature, were evaluated for As species extraction. The method provided a limit of detection of 0.013 ng mL−1 and a…