69 research outputs found
ΠΠ΅ΡΠΎΠ΄ ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ½ΠΎΠΉ ΡΠΏΠ΅ΠΊΡΡΠΎΡΠΊΠΎΠΏΠΈΠΈ Π΄Π»Ρ ΡΠ΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ²Π»Π°ΠΆΠ½Π΅Π½Π½ΡΡ Π·Π΅ΡΠ΅Π½ ΠΏΡΠ΅Π½ΠΈΡΡ
The authors presented the results of a study of the electrical and dielectric characteristics of wetted wheat grains by measuring their complex electrical resistance (impedance Z) in a wide frequency range (from 1 Hz to 100 MHz). The results of electrical impedance measurements of grains with surface or volumetric moisture content under different experimental conditions can provide useful information on the properties of the biological tissues of grain crops. These results can also be used to develop a new type of impedance sensor for testing grain quality and moisture content. The authors used well-dried wheat grains and grains saturated with moisture and saline as objects of research. A major problem in grain impedance measurements is the selection of a suitable electrode material to be placed on the end surfaces of the samples. The electrodes must ensure reliable contact with the grain and have a minimum transient resistance. The end surfaces of the pressed samples were reinforced with a protective dielectric ring to prevent transverse deformation. These contacts provided a transition resistance between 1-2 ohms. The authors have identified processes of accumulation of electric charges near the surface of metal electrodes at low frequencies and on internal grain structures, leading to an increase in the dielectric permittivity and dissipation factor. The behavior of the active and reactive components of the impedance at higher frequencies is determined by dielectric relaxation processes. The obtained impedance spectra were compared with the spectra of the most suitable equivalent electrical circuits. The radio components of the circuits provide information about the basic mechanisms of alternating electric current flow through the complex inhomogeneous structure of the grain. The authors found that moistening the grain with saline water enhances the process of accumulation of electric charges and affects the dispersion of the real and imaginary components of the impedance.ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ Π΄ΠΈΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ ΡΠ²Π»Π°ΠΆΠ½ΡΠ½Π½ΡΡ
Π·ΡΡΠ΅Π½ ΠΏΡΠ΅Π½ΠΈΡΡ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ ΠΈΡ
ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠ³ΠΎ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΡ (ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ° Z) Π² ΡΠΈΡΠΎΠΊΠΎΠΌ Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½Π΅ ΡΠ°ΡΡΠΎΡ (ΠΎΡ 1 ΠΡ Π΄ΠΎ 100 ΠΠΡ). Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ° Π·Π΅ΡΠ½Π° Ρ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΡΠΌ ΠΈΠ»ΠΈ ΠΎΠ±ΡΡΠΌΠ½ΡΠΌ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΠ΅ΠΌ Π²Π»Π°Π³ΠΈ Π² ΡΠ°Π·Π½ΡΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ° ΠΌΠΎΠ³ΡΡ Π΄Π°ΡΡ ΠΏΠΎΠ»Π΅Π·Π½ΡΡ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΡ ΠΎ ΡΠ²ΠΎΠΉΡΡΠ²Π°Ρ
Π±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠΊΠ°Π½Π΅ΠΉ Π·Π΅ΡΠ½ΠΎΠ²ΡΡ
ΠΊΡΠ»ΡΡΡΡ ΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΡΡΡ Π΄Π»Ρ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠΈ Π½ΠΎΠ²ΠΎΠ³ΠΎ ΡΠΈΠΏΠ° ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ½ΡΡ
Π΄Π°ΡΡΠΈΠΊΠΎΠ² Π΄Π»Ρ ΡΠ΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π·Π΅ΡΠ½Π° ΠΈ Π΅Π³ΠΎ Π²Π»Π°ΠΆΠ½ΠΎΡΡΠΈ. Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΎΠ±ΡΠ΅ΠΊΡΠ° ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»ΠΈΡΡ Ρ
ΠΎΡΠΎΡΠΎ Π²ΡΡΡΡΠ΅Π½Π½ΡΠ΅ Π·ΡΡΠ½Π° ΠΏΡΠ΅Π½ΠΈΡΡ ΠΈ Π·ΡΡΠ½Π°, Π½Π°ΡΡΡΠ΅Π½Π½ΡΠ΅ Π²Π»Π°Π³ΠΎΠΉ ΠΈ ΡΠΎΠ»Π΅Π²ΡΠΌ ΡΠ°ΡΡΠ²ΠΎΡΠΎΠΌ. Π‘Π΅ΡΡΡΠ·Π½ΠΎΠΉ ΠΏΡΠΎΠ±Π»Π΅ΠΌΠΎΠΉ ΠΏΡΠΈ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΡΡ
ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ° Π·ΡΡΠ΅Π½ ΡΠ²Π»ΡΠ΅ΡΡΡ Π²ΡΠ±ΠΎΡ ΠΏΠΎΠ΄Ρ
ΠΎΠ΄ΡΡΠ΅Π³ΠΎ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° ΡΠ»Π΅ΠΊΡΡΠΎΠ΄ΠΎΠ², Π½Π°ΠΊΠ»Π°Π΄ΡΠ²Π°Π΅ΠΌΡΡ
Π½Π° ΡΠΎΡΡΠ΅Π²ΡΠ΅ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΎΠ±ΡΠ°Π·ΡΠΎΠ². ΠΠ»Π΅ΠΊΡΡΠΎΠ΄Ρ Π΄ΠΎΠ»ΠΆΠ½Ρ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΠ²Π°ΡΡ Π½Π°Π΄ΡΠΆΠ½ΡΠΉ ΠΊΠΎΠ½ΡΠ°ΠΊΡ Ρ Π·Π΅ΡΠ½ΠΎΠΌ ΠΈ ΠΎΠ±Π»Π°Π΄Π°ΡΡ ΠΌΠΈΠ½ΠΈΠΌΠ°Π»ΡΠ½ΡΠΌ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄Π½ΡΠΌ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΠ΅ΠΌ. ΠΠ»Ρ ΠΈΡΠΊΠ»ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½ΠΎΠΉ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΡΠΎΡΡΠ΅Π²ΡΠ΅ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΏΡΠ΅ΡΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² ΡΠΊΡΠ΅ΠΏΠ»ΡΠ»ΠΈ Π·Π°ΡΠΈΡΠ½ΡΠΌ Π΄ΠΈΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΊΠΎΠ»ΡΡΠΎΠΌ. Π’Π°ΠΊΠΈΠ΅ ΠΊΠΎΠ½ΡΠ°ΠΊΡΡ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΠ²Π°Π»ΠΈ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄Π½ΠΎΠ΅ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΠ΅ Π² ΠΏΡΠ΅Π΄Π΅Π»Π°Ρ
1β2 ΠΠΌ. Π ΠΎΠ±Π»Π°ΡΡΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
ΡΠ°ΡΡΠΎΡ Π²ΡΡΠ²Π»Π΅Π½Ρ ΠΏΡΠΎΡΠ΅ΡΡΡ Π½Π°ΠΊΠΎΠΏΠ»Π΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π·Π°ΡΡΠ΄ΠΎΠ² Π²Π±Π»ΠΈΠ·ΠΈ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΌΠ΅ΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ»Π΅ΠΊΡΡΠΎΠ΄ΠΎΠ² ΠΈ Π½Π° Π²Π½ΡΡΡΠ΅Π½Π½ΠΈΡ
ΡΡΡΡΠΊΡΡΡΠ°Ρ
Π·Π΅ΡΠ½Π°, ΠΏΡΠΈΠ²ΠΎΠ΄ΡΡΠΈΠ΅ ΠΊ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΡ Π΄ΠΈΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΠ½ΠΈΡΠ°Π΅ΠΌΠΎΡΡΠΈ ΠΈ ΡΠ°Π½Π³Π΅Π½ΡΠ° ΡΠ³Π»Π° ΠΏΠΎΡΠ΅ΡΡ. Π ΠΎΠ±Π»Π°ΡΡΠΈ Π±ΠΎΠ»Π΅Π΅ Π²ΡΡΠΎΠΊΠΈΡ
ΡΠ°ΡΡΠΎΡ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΠ΅ Π°ΠΊΡΠΈΠ²Π½ΠΎΠΉ ΠΈ ΡΠ΅Π°ΠΊΡΠΈΠ²Π½ΠΎΠΉ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ° ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΡΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠ°ΠΌΠΈ Π΄ΠΈΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠΏΠ΅ΠΊΡΡΡ ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ° ΡΠΎΠΏΠΎΡΡΠ°Π²Π»ΡΠ»ΠΈΡΡ ΡΠΎ ΡΠΏΠ΅ΠΊΡΡΠ°ΠΌΠΈ Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ ΠΏΠΎΠ΄Ρ
ΠΎΠ΄ΡΡΠΈΡ
ΡΠΊΠ²ΠΈΠ²Π°Π»Π΅Π½ΡΠ½ΡΡ
ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΡ
Π΅ΠΌ, ΡΠ°Π΄ΠΈΠΎΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΡ ΠΊΠΎΡΠΎΡΡΡ
ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΠΏΠΎΠ½ΡΡΡ ΠΎΡΠ½ΠΎΠ²Π½ΡΠ΅ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΡ ΠΏΡΠΎΡ
ΠΎΠΆΠ΄Π΅Π½ΠΈΡ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΊΠ° ΡΠ΅ΡΠ΅Π· ΡΠ»ΠΎΠΆΠ½ΡΡ Π½Π΅ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½ΡΡ ΡΡΡΡΠΊΡΡΡΡ Π·Π΅ΡΠ½Π°. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΡΠ²Π»Π°ΠΆΠ½Π΅Π½ΠΈΠ΅ Π·Π΅ΡΠ½Π° ΠΏΠΎΠ΄ΡΠΎΠ»Π΅Π½Π½ΠΎΠΉ Π²ΠΎΠ΄ΠΎΠΉ ΡΡΠΈΠ»ΠΈΠ²Π°Π΅Ρ ΠΏΡΠΎΡΠ΅ΡΡ Π½Π°ΠΊΠΎΠΏΠ»Π΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π·Π°ΡΡΠ΄ΠΎΠ² ΠΈ Π²Π»ΠΈΡΠ΅Ρ Π½Π° Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΡ Π΄Π΅ΠΉΡΡΠ²ΠΈΡΠ΅Π»ΡΠ½ΠΎΠΉ ΠΈ ΠΌΠ½ΠΈΠΌΠΎΠΉ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ ΠΈΠΌΠΏΠ΅Π΄Π°Π½ΡΠ°
Facile Synthesis of Amine-Functionalized Eu3+-Doped La(OH)3 Nanophosphors for Bioimaging
Here, we report a straightforward synthesis process to produce colloidal Eu3+-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu3+ NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (Ξ»ex = 280 nm). The red emission, due to 5D0 β 7F1 and 5D0 β 7F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu3+ NPs possess the potential to serve as a luminescent bioimaging probe
Competitive quenching fluorescence immunoassay for chlorophenols based on laser-induced fluorescence detection in microdroplets
8 pages, 7 figures, 1 table.-- PMID: 12530822 [PubMed].-- Available online Nov 2, 2002.An improved biomonitoring system for the analysis of 2,4,6-trichlorophenol (TCP) in urine samples has been developed. The principle of the biosensor device is the detection of laser-induced fluorescence (LIF) in single microdroplets by a homogeneous quenching fluorescence immunoassay (QFIA). The competitive immunoassay occurs in microdroplets (d = 58,4 ΞΌm) produced by a piezoelectric generator system with 10-ΞΌm-diameter orifice. A continuous Ar ion laser (488 nm) excites the fluorescent tracer; its fluorescence is detected by a spectrometer attached to a 512 Γ 512 cooled, charge-coupled device camera. Fluorescence is quenched by specific binding of TCP polyclonal antibodies to the fluorescent tracer (hapten Aβfluorescein); the quenching effect is diminished by the presence of the analyte. Thus, an increase in the signal is produced in a positive dose-dependent manner when TCP is present in the sample. In 10 mM PBS buffer, the IC50 of the LIF-microdroplet QFIA is 0.45 ΞΌg L-1 reaching a LOD of 0.04 ΞΌg L-1. The QFIA with the same reagents performed in microtiter plate format achieved a LOD of 0.36 ΞΌg L-1 in buffer solution. Performance in human urine was similar to that observed in the buffer. A LOD of 1.6 ΞΌg L-1, with a dynamic range between 4 and 149.5 ΞΌg L-1 in urine, was obtained without any sample treatment other than dilution with the assay buffer. The detectability achieved is sufficient for occupational exposure risk assessment.This research was supported by the Superfund Basic Research Program from the National Institute of Environmental Health Sciences (Grant 5P42ES04699, NIH with funding provided by EPA), by the EC Program (Contract QLRT-2000-01670), and by the Spanish Government through CICYT (BIO2000-0351-P4-05). UCD is a NIEHS Environmental Health Center P30 ESO5707.Peer reviewe
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