The analytical capabilities of the method of atomic emission spectrometry on a two-jet arc plasma (TJP-OES) with the use of spark ablation and calibration using standard solutions are evaluated. ...Optimization of the conditions for the injection of solutions into the plasma of a two-jet arc plasmatron has been carried out. The effect of the concentration of matrix elements on the signal-to-background ratio was studied when solutions were injected into the plasma. Calibration was carried out using the coefficients of relative sensitivity factors and standard solutions. The use of spectral lines of analytes and an internal standard with similar energy characteristics made it possible to achieve accurate and reproducible results in determination of impurities in steel and copper samples.
For the first time, the injection of solutions into the plasma of a two-jet arc plasmatron was used for the analysis of metals and alloys. Tandem calibration was used for quantitative chemical analysis by the TJP-AES method.
The analytical capabilities of the atomic emission spectrometry method with a two-jet arc plasmatron (TJP-OES) using spark ablation are estimated. The influence of the frequency and duration of the ...discharge impulse, as well as the operating parameters of the plasma torch on the value of the analytical signal and standard deviation, has been studied. The dependences of the analytical signal on the duration of the spark discharge were obtained, and the optimal sparking time to obtain a stable signal has been found. The detection limits of Cr, Cu, Mn, Mo, Ni, Si, and V during the TJP-OES analysis of steel with spark ablation are in the range of
n
× 10
−5
÷
n
× 10
−3
wt%.
The analytical capabilities of the atomic emission spectrometry method with a two-jet arc plasmatron (TJP-OES) using spark ablation are estimated.
The effect of current strength, pre-batching time, frequency and duration of a discharge pulse, as well as the operational parameters of a two-jet arc plasma (TJP) torch (angle between plasma jets, ...gas flow) on the value of the analytical signal and standard deviation are studied. The influence of the operational parameters of spark ablation on the morphology and particle size of the resulting aerosol was studied. The optimal conditions for the analysis of steels by the method of TJP-OES with spark ablation were selected. The analytical capabilities of the method are evaluated in the analysis of steels. The limits of detection (LODs) for Cr, Cu, Mn, Mo, Ni, Si, and V during TJP-OES analysis of steels with spark ablation are in the range of n·10−5 ÷ n·10−3% wt.
Display omitted
•For the first time, spark ablation was used in combination with a two-jet arc plasmatron.•The use of spark ablation has expanded the field of application of the TJP-AES method.•The use of spark ablation simplifies sample preparation in the TJP-AES analysis of metals.•The smallest RSD was observed with pulse duration of 150 μs and a frequency of 500 Hz.•The detection limits for steel analysis are in the range from n·10−5% wt. to n·10−3% wt.
The synergistic effect of simultaneous mechanical wear, chemical/electrochemical corrosion (tribocorrosion) and microbial attack poses a serious threat to marine and coastal infrastructure. To ...address this important problem, we have developed composite coatings consisting of TaC (25–35 at.%) and a corrosion-resistant α-Fe(Cr,Ni,Mo)-based metal matrix, as well as bactericidal elements (Cu, Ag). Coatings 50–75 μm thick were obtained by electrospark deposition in vacuum. The coatings possess high hardness (up to 10 GPa) and resistance to cyclic dynamic loads compared with the stainless steel (SS) substrate. Tribocorrosion experiments showed that the decrease in the corrosion potential associated with the removal of a passivating film from the surface during friction was 2–2.5 times smaller for the Ag-containing coating than for the other tested materials. The material passivation rates were also different: almost instantaneous passivation of the Ag- and Cu-doped coatings, and slow passivation for several minutes of the Ag/Cu-free coating and SS. The Ag-containing coating shows the lowest friction coefficient (0.2–0.25) and a minimal wear rate (1.6 × 10−6 mm3/Nm) in artificial seawater. The Ag-doped coating also exhibits the most positive value of corrosion potential and the lowest current density. After exposure in seawater for 20 days, only the Ag-doped coating showed no signs of pitting corrosion. All the studied materials have a pronounced bactericidal effect against Bacillus cereus Arc30 bacteria. The resulting coatings can be used to protect steel products from tribocorrosion and fouling in seawater.
A study was carried out on the quality of the cobalt carbonate raw material and heat treatment conditions on the activity of Co-Mo and Ni-Mo hydrotreating catalysts for a mixed diesel fraction. The ...relevant properties of the impregnation solution are the purity of the cobalt carbonate starting material and the synthesis temperature. A Raman spectroscopic method was proposed for monitoring the cobalt carbonate quality. Heat treatment of the catalyst was found to affect its activity. The optimal ultimate calcination temperatures for the Co-Mo and Ni-Mo catalysts were found to be very different.
The developed approaches to increasing the analytical selectivity by laser Raman spectroscopy and the use of chemometrics and a proprietary algorithm for self-tuning calibration models with the ...efficiency and speed of the method have shown a rare and excellent opportunity for informationally equivalent on-line control of all technological stages of the production of poly-α-olefin oils and other products through a network of fiber-optic probes. Oligomers of C
6
, C
8
, and C
10
α-olefins obtained by heterogeneous chromium-oxide catalysis technology developed at LLC «RN-RD CENTER», as shown by the Raman spectra, differ from analogs obtained by homogeneous synthesis by the variety of unsaturated group structures and a greater width and variability of the molecular-mass distribution, which makes it possible to regulate a wide assortment of low- and high-molecular-mass products. A special case – the atypically high sensitivity of Raman spectra to the chain length – makes it possible during the synthesis to predict and adjust in real time the molecular mass of the oligomers and other target properties and to replace a fleet of traditional analytical equipment with one method.
Our previous work has revealed very high baseline neurogenesis in the dentate gyrus of wood mice as compared particularly to bank voles; a difference which may be related to learning capacity. This ...study explored whether the newly-developed Intellicage system could be used to compare these species in simple spatial learning paradigms. The Intellicage is essentially a group-housing cage that also allows continuous automatic recording of each individual’s behaviour. Seven wild-caught bank voles (
Clethrionomys glareolus) were compared with seven wild-caught long-tailed wood mice (
Apodemus sylvaticus) in the Intellicage system over 9 days. During the first 90
min after entering the cage, the wood mice were substantially more exploratory than the bank voles (
P = 0.003). Over subsequent days, both species showed nocturnal activity increases with voles being 3.7 times more active overall. In the spatial learning paradigms, there were significant species-by-time interactions with wood mice outperforming bank voles on both place learning (
P = 0.027) and subsequent reversal (
P = 0.006). Conclusions are firstly that the wood mice show superior learning abilities in this paradigm, and secondly that the Intellicage serves as a valuable cognitive testing arena for small wild rodents, or for circumstances where cognition must be compared independent of different responses to handling or novel environments.
A study was carried out on the effect of the nature of the support, composition of the active phase, and heat treatment conditions on the activity of trimetallic Ni‑Co‑Mo catalysts in the ...hydrotreating of a mixed diesel fraction. Temperature‑programmed desorption was used to show the effect of the amount and strength of the acid sites of the support on the activity of catalysts with the same elemental composition. We established the nickel‑to‑cobalt as well as phosphorus‑to‑molybdenum ratios in these trimetallic hydrotreating catalysts corresponding to the greatest desulfurization and minimum formation of polycyclic aromatic hydrocarbons in the hydrogenate.
—
Natal dispersal of young common shrews (
Sorex araneus
) was studied in field conditions in the southern part of Tver oblast, in central European Russia. Total individual marking of shrews was ...conducted over an area of 22 ha. The places of birth of the young were determined by the home ranges of relative overwintered females. The animals were genotyped by ten microsatellite loci: L62, L68, L45, C117, L69, C5, B30, D106, D103, and D138. Family analysis was carried out using the Cervus 3.07 software. In 2013, with the population density in October being 6.5 individuals/ha, 33 mother‒pup dyads were identified for 229 yearlings and 20 females. The share of yearlings born within the study area was 14.8%, while the core of the population consisted of animals that had arrived from outside the plot. In 2014, with the population density in October reaching only 2.6 individuals/ha, nine mother‒pup dyads were found for 58 yearlings and nine mature females. The share of the animals born within the plot boundaries was 15.5%. Within the plot, dispersal from the natal ranges varied from 0 to 610 m,
Me
= 224, in 2013, and from 45 to 410 m,
Me
= 297, in 2014. The data obtained fail to confirm a meaningful year-to-year difference. Taking into account the corrections for the proportion of territory under control, the majority of young animals appear to have dispersed over a range of more than 400 m both during the high fall population density and during its decrease the next year.
The aim of this work was a comparative investigation of the structure and properties of Al- and Cr-doped TiSiCN coatings deposited by magnetron sputtering of composite TiAlSiCN and TiCrSiCN targets ...produced by self-propagating high-temperature synthesis method. Based on X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy data, the Al- and Cr-doped TiSiCN coatings possessed nanocomposite structures (Ti,Al)(C,N)/a-(Si,C) and (Ti,Cr)(C,N)/a-SiCxNy/a-C with cubic crystallites embedded in an amorphous matrix. To evaluate the thermal stability and oxidation resistance, the coatings were annealed either in vacuum at 1000, 1100, 1200, and 1300°C or in air at 1000°C for 1h. The results obtained show that the hardness of the Al-doped TiSiCN coatings increased from 41 to 46GPa, reaching maximum at 1000°C, and then slightly decreased to 38GPa at 1300°C. The Cr-doped TiSiCN coatings demonstrated high thermal stability up to 1100°C with hardness above 34GPa. Although both Al- and Cr-doped TiSiCN coatings possessed improved oxidation resistance up to 1000°C, the TiAlSiCN coatings were more oxidation resistant than their TiCrSiCN counterparts. The TiCrSiCN coatings showed better tribological characteristics both at 25 and 700°C and superior cutting performance compared with the TiAlSiCN coatings.
► Hard Ti(Al,Cr)SiCN coatings for high-temperature tribological applications. ► Alloying with Al or Cr improves thermal stability of TiSiCN coatings. ► TiAlSiCN coatings show hardness above 37GPa from 25 to 1300°C. ► TiCrSiCN coatings demonstrate hardness above 34GPa up to 1100°C. ► Al- and Cr-doped TiSiCN coatings possess improved oxidation resistance up to 1000°C.
PDF