Search results for "probe"
showing 10 items of 534 documents
Detection and discrimination of organophosphorus pesticides in water by using a colorimetric probe array
2014
[EN] Detection and discrimination of several organophosphorus pesticides in water using a colorimetric probe array containing twelve dyes has been achieved. A clear discrimination for malathion, leptophos, dichlorvos, dibrom and diazinon was observed. The array was used to determine the concentration of diazinon in orange leaves
Aprobežotu aizgadības tiesību atjaunošana un bērna vislabāko interešu mijiedarbība.
2020
Bērna vislabāko interešu aizsardzība aprobežotu aizgādības tiesību atjaunošanas gadījumos ir aktuāla tēma mūsdienās, jo mainās sabiedrības vērtības un uzskati par labvēlīgas vides nodrošināšanu bērnam. Savukārt institūcijām, kas nodrošina bērna tiesību aizsardzību, visos gadījumos, kad ir apdraudēta bērna labklājība, jānodrošina bērna vislabākajām interesēm atbilstoša rīcība un lēmumi. Bakalaura darba mērķis ir noskaidrot vai Latvijas normatīvo aktu regulējums aprobežotu aizgādības tiesību atjaunošanas jautājumos nodrošina bērna tiesību aizsardzību un bērna vislabākajām interesēm atbilstošu risinājumu. Problēmas pastāv aprobežotu aizgādības tiesību atjaunošanas regulējumā, kā arī regulējumā…
Development of a Matrix-Matched Sphalerite Reference Material (MUL-ZnS-1) for Calibration of In Situ Trace Element Measurements by Laser Ablation-Ind…
2016
Sphalerite (ZnS) is an abundant ore mineral and an important carrier of elements such as Ge, Ga and In used in high-technology applications. In situ measurements of trace elements in natural sphalerite samples using LA-ICP-MS are hampered by a lack of homogenous matrix-matched sulfide reference materials available for calibration. The preparation of the MUL-ZnS1 calibration material containing the trace elements V, Cr, Mn, Co, Ni, Cu, Ga, Ge, As, Se, Mo, Ag, Cd, In, Sn, Sb, Tl and Pb besides Zn, Fe and S is reported. Commercially available ZnS, FeS, CdS products were used as the major components, whereas the trace elements were added by doping with single-element ICP-MS standard solutions a…
A chalcone-based highly selective and sensitive chromofluorogenic probe for trivalent metal cations
2015
[EN] Anew chalcone-based probe for the chromofluorogenic sens-ing of trivalent (Al3 +,Fe3+,Cr3+,Ga3+,In3+and As3 +)overmono-and divalent cationsand anionsisreported. In the presence of trivalent metal cations,the probe was able to displayaremarkable color change from yellow to colorless that wasclearly visible to the naked eye. Also, the initial strongyellowemission was gradually quenched and substituted by aweaklyshifted band.
Micropolarity and Order in the Reverse Micelles of L62 and L64 Pluronic Copolymers, As Studied by Molecular Probe Techniques
1998
The reverse micelles of triblock copolymers poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) EO6PO36EO6 (Pluronic L62) and EO13PO30EO13 (Pluronic L64) in ternary (copolymer/o-xylene/water) and binary (copolymer/water) systems with different water contents were evidenced and investigated by fluorescence, absorption, and spin probe techniques. The spectral parameters of the polarity sensitive probes, 1-anilinonaphthalene-8-sulfonic acid (ANS), dansylhexadecylamine (Dansyl), pyrenesulfonic acid (PSA), 4-nitropyridine N-oxide (NP) and 4-(N,N‘-dimethyl-N-alkyl)ammonium 2,2‘,6,6‘-tetramethylpiperidine-1-oxyl iodide (CAT n), were related to the local hydration and polari…
Light induced charging of polymer functionalized nanorods.
2010
ZnO nanorods were functionalized with new block copolymers containing a hole transporting moiety in one block and a dye and an anchor system in the second block. After functionalization, the ZnO nanorods are well dispersible in organic media and the fluorescence of the dye is quenched. Kelvin probe force microscopy was used to measure changes in electrical potential between the ZnO nanorod and the polymeric corona. Upon light irradiation, potential changes on the order of some tens of millivolts were observed on individual structures. This effect is attributed to light-induced charge separation between the ZnO nanorod and its hole transporting polymeric corona.
Forces Between Solid Surfaces Across Polymer Melts as Revealed by Atomic Force Microscopy
2007
Forces between solid surfaces across polymer melts are poorly understood despite their fundamental importance and their relevance for making composite materials. Such force measurements reveal information on the structure of polymers at surfaces and of confined polymers. Experiments with the atomic force microscope and polyisoprene (PI) confirmed theoretical predictions that no long‐range force should be present in thermodynamic equilibrium. In poly(dimethyl siloxane) (PDMS) repulsive forces are observed at high molar mass. We attribute this to the formation of an immobilized layer caused by a slow release of adsorbed segments enhanced by entanglement. In low molar mass PDMS attractive forc…
Tunable dynamic hydrophobic attachment of guest molecules in amphiphilic core–shell polymers
2016
In this study, synthesis and dynamic properties of amphiphilic core–shell polymers are reported as monitored through their interaction with small amphiphilic molecules. Brush-like structures are formed with a hydrophobic core surrounded by a hydrophilic shell utilizing controlled radical addition–fragmentation chain transfer (RAFT) polymerization of macromonomers consisting of linear polyglycerol chains attached to alkylene methacrylate. Continuous wave electron paramagnetic resonance (CW EPR) spectroscopy is employed to study how the amphiphilic, paramagnetic spin probe 16-DSA (16-doxyl stearic acid) interacts with polymers of different alkylene chain lengths in their hydrophobic cores and…
SPM and TOF-SIMS investigation of the physical and chemical modification induced by tip writing of self-assembled monolayers
2003
Abstract The nanoelectrochemical modification of alkyl self-assembled monolayers (SAMs) obtained on hydrogenated silicon surfaces via radical-initiated reactions of 1-octadecene has been investigated. Scanning Probe Microscopy (SPM) showed that the modification of the organic layer occurs by applying either positive or negative biases to the tip at a threshold of about ±5 V. When the bias absolute value was ≤6 V, the height of the monolayer was only faintly modified, whereas a consistent increase in tip/sample friction force was observed, in agreement with the formation of hydrophilic moieties at the organic surface. In addition to the increase of friction, bias absolute values larger than …
How Structure-Related Collapse Mechanisms Determine Nanoscale Inhomogeneities in Thermoresponsive Polymers
2012
Continuous wave electron paramagnetic resonance (CW EPR) spectroscopy on the amphiphilic spin probe TEMPO in solutions of selectively chosen functional, thermoresponsive poly(propylene oxide) (PPO)- and poly(ethylene oxide) (PEO)-based copolymers of both linear and branched structure is used to elucidate their host–guest interactions and inverse phase transitions. Three different fundamental types of host–guest interactions between probes and polymers could be correlated to the phase transition mechanisms (supported by MD simulations), evidencing that these proceed via nanoscale inhomogeneities of the polymers. Because of their ability to host small amphiphilic guest molecules, thermorespon…