Search results for "Dilution"

Contributions regarding increasing reliability of beer industry installations using weld cladding in ultrasonic field

2016

Paper presents a new technology for availability increasing of different installation parts used in beer industry - ultrasonic activation of metal deposition by welding. The dilution phenomenon is studied linked on its influence upon material technological and functional properties in the three distinct zones of resulted couple (filler material, influenced thermal zone, base material). Experimental results performed on unidirectional valve are presented regarding variation of chemical composition concentration and dilution variation in three zones influenced by ultrasonic wave.

Dynamic light scattering by preserved skimmed cow milk: A comparison of two-colour and three-dimensional cross-correlation experiments

2008

We investigate the dynamic light scattering of preserved skimmed cow milk and compare the performance of a standard two-colour (2C) cross-correlation setup with the recently developed three-dimensional (3D) cross-correlation setup. Undiluted milk could only be investigated using the 3D setup because of too low signal-to-noise ratio of the 2C setup. A tenfold diluted milk, however, could be investigated by both setups, and comparable results for the dynamics of the sample were obtained thus demonstrating the equivalence of the decorrelation schemes. On the other hand, we found that the dynamics of the milk is strongly altered upon dilution. This finding elucidates the benefits of the new 3D …

MÖSSBAUER EFFECT STUDY ON THE HIGH-SPIN (5T2) ⇌ LOW SPIN (1A1) TRANSITION IN [Fe(2-pic)3]Cl2. DILUTION EFFECT IN [FexZn1-x(2-pic)3] Cl2. EtOH AND CRY…

1976

Structure and Dilution of Mesogenic Side Chains in Liquid Crystalline Polysiloxanes

1988

Abstract The structure of the smectic phases in four series of homo- and copolymers based on dimethylsiloxane chains with a definite variation of the concentration of the paired mesogenic side chains has been investigated by means of X-ray methods. The dilution of the mesogenic moiety was achieved by insertion of additional dimethylsiloxane segments. A nearly linear dependence of the layer spacings on the dilution has been found. A model of the structure is proposed which consists of two sublayers one of which contains the irregularly arranged main chain whereas the other one is formed by the side chains.

Quantification of Listeria monocytogenes in salads by real time quantitative PCR

2005

Abstract A real time quantitative PCR (RTQ-PCR) was carried out purifying DNA extracts of Listeria monocytogenes using a High Pure Listeria Sample Preparation Kit and quantifying in a LightCycler system with hybridisation probes. A standard curve was constructed with serial dilutions. A range linear relationship, from 10 to 10 5 L. monocytogenes colony forming units (CFU), was observed between threshold cycle ( C t ) and logarithmic concentration of the serial dilutions. The assay was linear in a range from 10 to 10 5 L. monocytogenes CFU and the coefficient of determination ( r 2 ) was > 0.98. RTQ-PCR presented an efficiency of > 85%. The accuracy of the PCR-based assay, expressed as % bia…

Development of a real-time PCR assay for detection and quantification of enterotoxigenic members of Bacillus cereus group in food samples

2009

A highly sensitive real-time PCR (qPCR) procedure, targeting the phosphatidylcholine-specific phospholipase C gene (pc-plc), was developed for specific detection and quantification of strains belonging to Bacillus cereus group. The target region was selected based on the enterotoxigenic profiles of 75 Bacillus strains. The inclusivity and exclusivity of the RTi-PCR assay were assessed with 59 isolates of the B. cereus group, 16 other Bacillus spp., and 4 non-Bacillus strains. The assay was also used to construct calibration curves for different food matrices, and it had a wide quantification range of 6 log units using both serial dilutions of purified DNA and calibrated cell suspensions of …

A TaqMan-based real-time PCR assay for the specific detection and quantification ofLeuconostoc mesenteroidesin meat products

2007

A new real-time PCR procedure was developed for the specific detection and quantification of Leuconostoc mesenteroides in meat products. It is a TaqMan assay based on 23S rRNA gene targeted primers and probe. Specificity was evaluated using purified DNA from 132 strains: 102 lactic acid bacteria (LAB), including 57 reference strains and 46 food isolates, belonging to genus Leuconostoc and related genera, and 30 non-LAB strains. Quantification was linear over at least 5 log units using both serial dilutions of purified DNA and calibrated cell suspensions from Leuconostoc mesenteroides ssp. dextranicum CECT 912T. This assay was able to detect at least five genomic equivalents, using purified …

Determination of acrylamide in coffee and chocolate by pressurised fluid extraction and liquid chromatography-tandem mass spectrometry.

2007

A selective and sensitive procedure has been developed and validated for the determination of acrylamide in difficult matrices, such as coffee and chocolate. The proposed method includes pressurised fluid extraction (PFE) with acetonitrile, florisil clean-up purification inside the PFE extraction cell and detection by liquid chromatography (LC) coupled to atmospheric pressure ionisation in positive mode tandem mass spectrometry (APCI-MS-MS). Comparison of ionisation sources (atmospheric pressure chemical ionisation (APCI), atmospheric pressure photoionization (APPI) and the combined APCI/APPI) and clean-up procedures were carried out to improve the analytical signal. The main parameters aff…

Cr(III)/Cr(VI) speciation in aerosol particles by extractive separation and thermal ionization isotope dilution mass spectrometry

1997

An isotope dilution mass spectrometric (IDMS) method, using the formation of positive thermal ions, was developed for Cr(III) and Cr(VI) speciation in aerosol particles. Cr(III) and Cr(VI) spike species, enriched in 53Cr, were applied for the isotope dilution step. After leaching of filter collected aerosol samples by an alkaline solution at pH 13, species separation was carried out by extraction with a liquid anion exchanger in methyl isobutyl ketone. Cr(VI) in the organic phase was re-extracted into an ammoniacal solution and chromium was then isolated from both fractions of species by electrodeposition. Detection limits of 30 pg/m3 for Cr(III) and of 8 pg/m3 for Cr(VI) were achieved in a…

Determination of uranium in tap water by ICP-MS

2000

A fast and accurate procedure has been developed for the determination of uranium at microg L(-1) level in tap and mineral water. The method is based on the direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma mass spectrometer (ICP-MS). Uranium was determined at the mass number 238 using Rh as internal standard. The method provides a limit of detection of 2 ng L(-1) and a good repeatability with relative standard deviation values (RSD) about 3% for five independent analyses of samples containing 73 microg L(-1) of uranium. Recovery percentage values found for the determination of uranium in spiked natural samples varied between 91% and 106%…