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71.
Marildes Josefina Lemos Neto Elizabeth de Souza Nascimento Vera Akiko Maihara Paulo Sergio C. Silva Mariza Landgraf 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(2):573-579
Three CRMs of different matrix composition were analysed, representing an environmental matrix sample (BCR–320R Channel Sediment), a botanical matrix sample (SRM 1547 Peach Leaves) and a zoological matrix sample (SRM 1566b Oyster Tissue). The element mass fractions were obtained using the KayWin program. Analytical measurement uncertainty was determined by two approaches: (1) the routine procedure applying combination of the overall uncertainty u(m) = 3.5 % and statistical uncertainty of the peak area determination and (2) the procedure applying the dedicated ERON program for calculating uncertainty. Performance of altogether 31 certified values was tested by means of calculating E n numbers. For the remaining 52 non-certified values, comparison between uncertainties obtained by the two approaches was made. When using the first approach, the E n number showed satisfactory performance in 28 cases; by using the second approach, the E n number showed satisfactory performance in 27 cases. None of the unsatisfactory performances (E n > 1) appeared to be of systematic nature. The uncertainties obtained by applying the two approaches revealed a big extent of consistency. As the present nuclear database lacks lot of data that serve as input to the ERON program, in particular uncertainties of Q 0 factors, estimates need to be introduced for the missing values, emphasising the urgent need to upgrade the database with missing data. 相似文献
72.
Fbio Bernardo Providencia Gonzlez-Hernndez Nuno Ratola Vernica Pino Arminda Alves Vera Homem 《Molecules (Basel, Switzerland)》2021,26(11)
Volatile methylsiloxanes (VMSs) constitute a group of compounds used in a great variety of products, particularly personal care products. Due to their massive use, they are continually discharged into wastewater treatment plants and are increasingly being detected in wastewater and in the environment at low concentrations. The aim of this work was to develop and validate a fast and reliable methodology to screen seven VMSs in water samples, by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The influence of several factors affecting the extraction efficiency was investigated using a design of experiments approach. The main factors were selected (fiber type, sample volume, ionic strength, extraction and desorption time, extraction and desorption temperature) and optimized, employing a central composite design. The optimal conditions were: 65 µm PDMS/Divinylbenzene fiber, 10 mL sample, 19.5% NaCl, 39 min extraction time, 10 min desorption time, and 33 °C and 240 °C as extraction and desorption temperature, respectively. The methodology was successfully validated, showing low detection limits (up to 24 ng/L), good precision (relative standard deviations below 15%), and accuracy ranging from 62% to 104% in wastewater, tap, and river water samples. 相似文献
73.
Krasnov Victor P. Zarubaev Vladimir V. Gruzdev Dmitry А. Vozdvizhenskaya Olga А. Vakarov Sergey А. Musiyak Vera V. Chulakov Evgeny N. Volobueva Alexandrina S. Sinegubova Ekaterina O. Ezhikova Marina А. Kodess Mikhail I. Levit Galina L. Charushin Valery N. 《Chemistry of Heterocyclic Compounds》2021,57(4):498-504
Chemistry of Heterocyclic Compounds - A number of novel amides were synthesized by coupling of 6-[(9H-purin-6-yl)amino]hexanoic acid to heterocyclic amines. The antiviral activity of the obtained... 相似文献
74.
Kokol Vanja Vivod Vera Peršin Zdenka Čolić Miodrag Kolar Matjaž 《Cellulose (London, England)》2021,28(10):6545-6565
Cellulose - Bio-based, renewable and biodegradable products with multifunctional properties are also becoming basic trends in the textile sector. In this frame, cellulose nanofibrils (CNFs) have... 相似文献
75.
Olga Kirichenko Gennadiy Kapustin Vera Nissenbaum Igor Mishin Leonid Kustov 《Journal of Thermal Analysis and Calorimetry》2014,118(2):749-758
The applications of zerovalent iron nanoparticles (nZVI) exploit their high reactivity which decreases due to oxidation in aerobic conditions during manufacture, application, and storage. In this study, we present the new procedure for estimation of the nZVI stability to oxidation in air. The procedure is suitable for characterization of the novel materials based on the supported nZVI. Nanoscale particles were synthesized inside porous silica supports by incipient wetness impregnation with the metal precursor solutions followed by thermal treatment. The TG–DTA studies revealed the decomposition temperature of the supported precursors, as well as the interaction of Fe and precious metal precursors, which resulted in the formation of alloy nanoparticles. Characterization of the samples by XRD confirmed the formation of the nanoparticles of the metallic Pd, Pt, and Fe phases supported on SiO2 carriers, as well as the formation of solid solutions based on the structure of precious metals. The new procedure for estimation of the nZVI stability included (1) TPR with hydrogen up to 400–425 °C followed by isothermal reduction at these temperatures; (2) in situ reoxidation with oxygen at room temperature. The samples were reduced “as obtained” and after in situ reoxidation. The results of the TPR studies exhibited that introduction of both Pd and Pt protected the Fe nanoparticles from oxidation with oxygen and air at ambient conditions. 相似文献
76.
Vera Yu Mishina Mikhail K. Gratchev Konstantin L. Anfilov Il'dar G. Mustafin Anna R. Bekker Edward E. Nifantyev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract The effective methods of phosphorylation of complex systems with specifically orientated in space hydroxyl groups, namely dianhydro-D-mannitol(A), -D-sor-bitol(B), cyclodextrines(C), and cellulose(D) (A-D, where R=H), have been elaborated. 相似文献
77.
Mathematical theory of optimization has found many applications in the area of medicine over the last few decades. Several
data analysis and decision making problems in medicine can be formulated using optimization and data mining techniques. The
significance of the mathematical models is greatly realized in the recent years owing to the growing technological capabilities
and the large amounts of data available. In this paper, we attempt to give a brief overview of some of the most interesting
applications of mathematical programming and data mining in medicine. In the overview, we include applications like radiation
therapy treatment, microarray data analysis, and computational neuroscience. 相似文献
78.
79.
MaxwellD. Cummings Jimmy Lindberg Tse‐I Lin Herman deKock Oliver Lenz Elisabet Lilja Sara Fellnder Vera Baraznenok Susanne Nystrm Magnus Nilsson Lotta Vrang Michael Edlund sa Rosenquist Bertil Samuelsson Pierre Raboisson Kenneth Simmen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2010,122(9):1552-1552
80.
Dr. Nina Erini Vera Beermann Martin Gocyla Manuel Gliech Dr. Marc Heggen Dr. Rafal E. Dunin-Borkowski Prof. Peter Strasser 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6633-6638
Direct ethanol fuel cells are attractive power sources based on a biorenewable, high energy-density fuel. Their efficiency is limited by the lack of active anode materials which catalyze the breaking of the C−C bond coupled to the 12-electron oxidation to CO2. We report shape-controlled PtNiRh octahedral ethanol oxidation electrocatalysts with excellent activity and previously unachieved low onset potentials as low as 0.1 V vs. RHE, while being highly selective to complete oxidation to CO2. Our comprehensive characterization and in situ electrochemical ATR studies suggest that the formation of a ternary surface site ensemble around the octahedral Pt3Ni1Rhx nanoparticles plays a crucial mechanistic role for this behavior. 相似文献