Search results for "ICP"
showing 10 items of 139 documents
Non-Matrix-Matched Calibration for the Multi-Element Analysis of Geological and Environmental Samples Using 200 nm Femtosecond LA-ICP-MS: A Compariso…
2014
LA-ICP-MS is one of the most promising techniques for in situ analysis of geological and environmental samples. However, there are some limitations with respect to measurement accuracy, in particular for volatile and siderophile/chalcophile elements, when using non-matrix-matched calibration. We therefore investigated matrix-related effects with a new 200 nm femtosecond (fs) laser ablation system (NWRFemto200) using reference materials with different matrices and spot sizes from 10 to 55 μm. We also performed similar experiments with two nanosecond (ns) lasers, a 193 nm excimer (ESI NWR 193) and a 213 nm Nd:YAG (NWR UP-213) laser. The ion intensity of the 200 nm fs laser ablation was much l…
(Table 1) Geochemistry of ODP Site 160-963 sediments
2010
The Mediterranean Sea acts as a miniature ocean with the development of its own conveyor belt. It constitutes an ideal location to study and forecast how the marine environment responds to rapid climatic change. Here we present a palaeoenvironmental study carried out on the sediments of ODP Site 963, recovered in the Sicily Channel, the sill which divides the western from the eastern Mediterranean basin. We focused on the transition between the penultimate glacial (MIS 6) and the last interglacial (MIS 5), between approximately 130 and 115 kyr BP. A novel approach is proposed, taking into account centennial-scale geochemical data on major elements, selected trace elements, and yttrium and R…
(Table 1) Trace element/Ca ratios of Orbulina universa shells from late Neogene Mediterranean samples
2008
A Mediterranean composite sedimentary record was analyzed for Ba/Ca ratios on carbonate shells of Orbulina universa planktonic foraminifer (Ba/Ca)carb providing the opportunity to study and assess the extent of freshwater inputs on the basin and possible impacts on its dynamics during the Tortonian to Recent period. A number of scanning electron microscope analyses and auxiliary trace element measurements (Mn, Sr, and Mg), obtained from the same samples, exclude important diagenetic effects on the studied biogenic carbonates and corroborate the reliability of (Ba/Ca)carb ratios in foraminifera calcite as indicators of seawater source components during the studied interval. A long-term trend…
Calcium Carbonate and Phosphate Reference Materials for Monitoring Bulk and Microanalytical Determination of Sr Isotopes
2017
In situ laser ablation analyses rely on the microanalytical homogeneity of reference materials (RMs) and a similar matrix and mass fraction between unknown samples and RMs to obtain reliable results. Suitable carbonate and phosphate RMs for determination of Sr isotope ratios in such materials are limited. Thus, we determined Sr-87/Sr-86 ratios of several carbonate (JCt-1, JCp-1, MACS-1, MACS-3) and phosphate (MAPS-4, MAPS-5, NIST SRM 1400, NIST SRM 1486) international RMs using dissolved samples and two different multi-collector inductively coupled plasma-mass spectrometers (MC-ICP-MS). Our Sr isotope data are in agreement with published data and have an improved measurement precision for s…
Pelnu ietekme uz elementu saturu gurķu augos (Cucumis sativus)
2021
. Pelnu ietekme uz elementu saturu gurķu augos (Cucumis Sativus). Kļaviņš D., zinātniskais vadītājs Mg. Chem. Bērtiņš M. Bakalaura darbs, 41 lappuse, 31 attēls, 4 tabulas, 34 literatūras avoti. Latviešu valodā. Darbā tika veikta gurķu stādu audzēšana kūdrā ar pelnu mēslojumu un bez tā. Paraugu sagatavošanai izmantoja slapjo mikroviļņu mineralizāciju. Makroelementu un mikroelementu koncentrācijas noteikšana tika veikta, izmantojot induktīvi saistītas plazmas masspektometrija.
Meliorācijas ietekme uz Vesetnieku ekoloģiskā stacionāra kūdras augsnes ķīmisko sastāvu
2015
Darbā pētīti nosusinātā un nenosusinātā pārejas tipa purva augsnes paraugi, sadarbībā ar Latvijas Valsts mežzinātnes institūta „Silava” pētniekiem. Darba ietvaros ķīmiskajām analīzēm kūdras paraugi ņemti no 6 parauglaukumiem, no noteiktiem augsnes dziļumiem (O horizonts, 0-10 cm, 10-20 cm, 20-40 cm, 40-80 cm, kopā 26 paraugi). Augsnes paraugiem noteikta oglekļa un slāpekļa stabilo izotopu attiecība, 1 M HNO3 ekstrahējamo Fe, Zn, Cu, Mn, K, Pb, Cr, Cd un Ni saturs, augsnes pH un homogenitāte. Noteikta elementu analizatora izotopu attiecības masspektrometra mērījumu linearitāte un stabilitāte ar laboratorijas references materiāla.
Zāļu tēju raksturošana ar ICP-MS, FTIR un spektroradiometrijas metodēm
2021
Zāļu tēju raksturošana ar ICP-MS, FTIR un spektroradiometrijas metodēm Sleže V., zinātniskais vadītājs prof. Dr. Chem. Vīksna A., konsultants Mg. Chem. Bērtiņš M. Maģistra darbs, 56 lappuses, 16 attēli, 8 tabulas, 61 literatūras avoti. Latviešu valodā. Tēja ir iecienīts ikdienas dzēriens miljoniem cilvēku katru dienu. Mūsdienās arvien vairāk cilvēku interesējās par kvalitatīviem produktiem. Tā kā tēja ir tik svarīga sastāvdaļa no pasaules ekonomikas, ir svarīgi piemeklēt modernas analīžu metodes, kas spēj pārbaudīt to unikālo sastāvu. Maģistra darbā tika analizēti Latvijā pieejamu zāļu tēju – liepziedu, kumelīšu, kliņģerīšu, bērzu pumpuru, pelašķu un karkādes – mikro un makroelementi ar ICP…
Intracranial pressure monitoring in patients with acute brain injury in the intensive care unit (SYNAPSE-ICU): an international, prospective observat…
2021
Background: The indications for intracranial pressure (ICP) monitoring in patients with acute brain injury and the effects of ICP on patients’ outcomes are uncertain. The aims of this study were to describe current ICP monitoring practises for patients with acute brain injury at centres around the world and to assess variations in indications for ICP monitoring and interventions, and their association with long-term patient outcomes. Methods: We did a prospective, observational cohort study at 146 intensive care units (ICUs) in 42 countries. We assessed for eligibility all patients aged 18 years or older who were admitted to the ICU with either acute brain injury due to primary haemorrhagic…
Corrosion resistance of passive films on different stainless steel grades in food and beverage industry
2020
Abstract Passive films were grown on 304 L, 316 L and Duplex stainless steels by immersion at open circuit potential in solutions mimicking food and beverage industry environments. In acidic food stainless steel surfaces are covered by Cr rich passive films, and generalized dissolution occurs on their surface with consequent ions release into the electrolyte. In fatty food the concentration of released ions is significantly lower since generalized corrosion does not occur, but the loss on MnS inclusions strongly reduces the polarization resistance in this environment especially for 304 L due to its higher localized corrosion susceptibility with respect to the other grades.
New process of silicon carbide purification intended for silicon passivation
2017
Abstract In this work, we report on a new, efficient and low cost process of silicon carbide (SiC) powder purification intended to be used in photovoltaic applications. This process consists on the preparation of porous silicon carbide layers followed by a photo-thermal annealing under oxygen atmosphere and chemical treatment. The effect of etching time on impurities removal efficiency was studied. Inductively coupled plasma atomic emission spectrometry (ICP-AES) results showed that the best result was achieved for an etching time of 10 min followed by gettering at 900 °C during 1 h. SiC purity is improved from 3N (99.9771%) to 4N (99.9946%). Silicon carbide thin films were deposited onto s…