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51.
J. Oberauskas P. Serapinas J. Salkauskas V. Svedas 《Spectrochimica Acta Part B: Atomic Spectroscopy》1981,36(8):799-807
Spark discharges between Al and Al-Cu electrodes in air at atmospheric pressure were studied. The probability distributions of fluctuations of the temperature, the intensities of some spectral lines of AI III, Al II Cu II and N II ions and the densities of the relevant particles, as well as various correlation characteristics were measured. The relationship between the measured characteristics and plasma, and spectral-line parameters is discussed. 相似文献
52.
53.
Petras Serapinas 《Accreditation and quality assurance》2007,12(11):569-574
Good correspondence between evaluations of the proficiency testing data for water measurements according to different scoring
schemes was found as a result of implementation of the measurement quality according to the target uncertainty defined in
the Drinking Water Directive. The accuracy of the evaluation is determined by the uncertainty of the assigned value, and this
uncertainty should be in correspondence with the target uncertainty. Modification of the zeta-score by the thorough application of the target uncertainty is presented. It is convenient for generalised presentation of
the proficiency testing data. The allowed bias is included as a linear term on the measured value scale, as it is treated
in uncertainty analysis. The importance of implementation of the target measurement uncertainty in other fields of the routine
measurements is indicated. 相似文献
54.
Fourier analysis of the real-time quality-control charts for colorimetric, photometric, and pH soil measurements shows 1/f
n
(n=1±0.05) noise intensity dependence on frequency, in correspondence to the earlier test for atomic absorption measurements. In addition, the prevailing character of the sample preparation in the general noise frequency dependence is clearly demonstrated. Some important analytical problems are addressed where knowledge of the specific character of the time variation in the analytical data sets is essential. 相似文献
55.
S. V. Petras 《Journal of Mathematical Sciences》1979,11(3):466-477
The paper is concerned with the behavior of the poles (resonances) of the analytic continuation to the nonphysical sheet of the resolvent of the Dirichlet problem for the operator
in the exterior of a trapping domain as the channel connecting the cavity with the exterior of the trap closes up. It is proved that the set of poles decomposes into two series one of which approaches the eigenvalues of the Dirichlet problem in the cavity and the other the resonances of the exterior of the closed trap.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 51, pp. 155–169, 1975.In conclusion, the author wishes to thank B. S. Pavlov for supervision of the work and V. G. Maz'ya and V. A. Solonnikov for useful discussions. 相似文献
56.
K. Petras 《Acta Mathematica Hungarica》1999,83(3):241-250
Denote by R
n
G
the remainder functional of the Gaussian quadrature formula involving n nodes. Using an elementary method, we derive the asymptotically best possible inequalities
and
from bounds for the second Peano kernel of R
n
G
. 相似文献
57.
The flowers of Narcissus poeticus are used for the isolation of valuable fragrance substances. So far, as the majority of these substances consist of volatile and sensitive to heat compounds, there is a need of developing effective methods for their recovery. In this study, freeze-dried N. poeticus inflorescences were extracted with pure supercritical CO2 (SFE-CO2) and its mixture with 5% co-solvent ethanol (EtOH) at 40 °C. Extract yields varied from 1.63% (12 MPa) to 3.12% (48 MPa, 5% EtOH). In total, 116 volatile compounds were identified by GC-TOF/MS in the extracts, which were divided into 20 different groups. Benzyl benzoate (9.44–10.22%), benzyl linoleate (1.72–2.17%) and benzyl alcohol (0.18–1.00%) were the major volatiles among aromatic compounds. The amount of the recovered benzyl benzoate in N. poeticus SFE-CO2 extracts varied from 58.98 ± 2.61 (24 MPa) to 91.52 ± 1.36 (48 MPa) mg/kg plant dry weight (pdw). α-Terpineol dominated among oxygenated monoterpenes (1.08–3.42%); its yield was from 9.25 ± 0.63 (12 MPa) to 29.88 ± 1.25 (48 MPa/EtOH) mg/kg pdw. Limonene was the major monoterpene hydrocarbon; (3E)-hexenol and heneicosanol dominated among alcohols and phenols; dihydroactinidiolide and 4,8,12,16-tetramethyl heptadecan-4-olide were the most abundant lactones; heptanal, nonanal, (2E,4E)-decadienal and octadecanal were the most abundant aldehydes. The most important prenol lipids were triterpenoid squalene, from 0.86 ± 0.10 (24 MPa) to 7.73 ± 0.18 (48 MPa/EtOH) mg/kg pdw and D-α-tocopherol, from 1.20 ± 0.04 (12 MPa) to 15.39 ± 0.31 (48 MPa/EtOH) mg/kg pdw. Aliphatic hydrocarbons (waxes) constituted the main part (41.47 to 54.93%) in the extracts; while in case of a 5% EtOH the percentage of alkanes was the lowest. The fraction of waxes may be removed for the separation of higher value fragrance materials. In general, the results obtained are promising for a wider application of SFE-CO2 for the recovery of fragrance substances from N. poeticus flowers. 相似文献
58.
Saveliy Belkin Petras J. Kundrotas Ilya A. Vakser 《Journal of computer-aided molecular design》2018,32(7):769-779
Modulating protein interaction pathways may lead to the cure of many diseases. Known protein–protein inhibitors bind to large pockets on the protein–protein interface. Such large pockets are detected also in the protein–protein complexes without known inhibitors, making such complexes potentially druggable. The inhibitor-binding site is primary defined by the side chains that form the largest pocket in the protein-bound conformation. Low-resolution ligand docking shows that the success rate for the protein-bound conformation is close to the one for the ligand-bound conformation, and significantly higher than for the apo conformation. The conformational change on the protein interface upon binding to the other protein results in a pocket employed by the ligand when it binds to that interface. This proof-of-concept study suggests that rather than using computational pocket-opening procedures, one can opt for an experimentally determined structure of the target co-crystallized protein–protein complex as a starting point for drug design. 相似文献
59.
Leader Peptide‐Free In Vitro Reconstitution of Microviridin Biosynthesis Enables Design of Synthetic Protease‐Targeted Libraries 下载免费PDF全文
Emmanuel Reyna‐González Bianca Schmid Dr. Daniel Petras Prof. Dr. Roderich D. Süssmuth Prof. Dr. Elke Dittmann 《Angewandte Chemie (International ed. in English)》2016,55(32):9398-9401
Microviridins are a family of ribosomally synthesized and post‐translationally modified peptides with a highly unusual architecture featuring non‐canonical lactone as well as lactam rings. Individual variants specifically inhibit different types of serine proteases. Here we have established an efficient in vitro reconstitution approach based on two ATP‐grasp ligases that were constitutively activated using covalently attached leader peptides and a GNAT‐type N‐acetyltransferase. The method facilitates the efficient in vitro one‐pot transformation of microviridin core peptides to mature microviridins. The engineering potential of the chemo‐enzymatic technology was demonstrated for two synthetic peptide libraries that were used to screen and optimize microviridin variants targeting the serine proteases trypsin and subtilisin. Successive analysis of intermediates revealed distinct structure–activity relationships for respective target proteases. 相似文献
60.
Maris Lauberts Galina Telysheva Petras Rimantas Venskutonis Liga Lauberte Tatiana Dizhbite Rita Kazernavičiūte Audrius Pukalskas 《Chemical Papers》2017,71(5):1007-1012
Diarylheptanoid-rich extracts (DAHEs) isolated from grey and black alder bark with pressurized ethyl acetate were tested in mayonnaise as a dietary antioxidant using the Oxipres method. DAHE contains >700 mg g?1 of oregonin possessing quite similar structure to the well-known dietary antioxidant curcumin, which is widely used as a bioactive constituent of food supplements. Strong radical scavenging capacity of oregonin was clearly demonstrated by the online HPLC–DPPH? scavenging assay. The antioxidative effect of DAHEs in mayonnaise was dose dependent; however, even the lowest concentration (0.5 mg g?1) of DAHE additive increased the induction period of oxidation more than two times. Consequently, DAHE may be considered as a promising natural antioxidant for commercial applications. 相似文献