It was shown that hexamethylenetetramine (HMT) is a new effective fuel for single-step solutions combustion synthesis (SCS) of supported Ni catalysts for methane decomposition into hydrogen and ...nanofibrous carbon. Several generalized chemical equations reflecting different ideas about combustion of the HMT−Ni(NO3)2−Cu(NO3)2−Al(NO3)3−H2O system have been derived. On the basis of those equations the adiabatic combustion temperature (Tad) and the amount of gaseous products (ng) have been calculated depending on the ignition temperature (T1), water content (m), excess fuel coefficient (φ), and the composition of the obtained solid product. The calculations have shown that Tad, depending on m and φ, changes from hundreds to thousands of degrees Kelvin. Increase of Al2O3 content in the catalyst up to 0.6 increases Tad by hundreds of degrees, and that increase of the Ni:NiO ratio up to 0.5 lowers Tad by tens of degrees. Three samples of the supported unreduced 0.97NiO/0.03Al2O3 catalyst were successfully prepared with the help of the SCS method using HMT as the fuel at φ=0.7. Those samples, obtained at reaction mixture preliminary heating rates V = 1, 10, 15 K/min were characterised using XRD, TEM, and SEM, and further tested in a pure methane decomposition reaction (100 LCH4/h/gcat, 823К, 1 bar). Nanoparticles of metal Ni were found in the SCS products, in contrast to cases when other types of fuel were used with φ<1. The experimental results showed that the higher is V, the higher is the maximum SCS temperature, the larger is the average size of Ni nanoparticles in unreduced catalyst, the higher is the stability of unreduced catalyst (up to 14 h) and the higher is the specific yield of hydrogen (up to 818 mol/molcat) during the deactivation period. The activity value of our unreduced catalyst (0.7 mol/h/gcat) in the methane decomposition reaction is close to maximum activity values of pre-reduced Ni catalysts of different nature reported in published articles.
•Generalized chemical equations for different SCS conditions were derived.•Adiabatic SCS temperature increases at higher Al2O3 content in an obtained catalyst.•Unreduced catalyst obtained by SCS has a high activity in methane decomposition.•Metallic Ni is in SCS products at fuel shortage due to hexamethylenetetramine use.
Effect of a GBK acidic system developed by the Institute of Petroleum Chemistry of the Siberian Branch of Russian Academy of Sciences (IPC SB RAS), on the composition of oil produced and on the ...reservoir microflora has been studied under both laboratory and field conditions. Under laboratory conditions, the integrated effect of the reservoir microflora and the acidic system manifested itself in a growth in the degrees of oxidation and aromaticity of the oil, in changes in its group composition and molecular weight distribution of mono-, bi-, and triaromatic hydrocarbons, as well as in the content of cyclones. Under field conditions, the efficiency of the GBK acidic treatment of low-productivity wells amounted to about 2,000 tons of incrementally produced oil per well job. This was achieved due to the inclusion of additional interlayers having different oil compositions and due to the desorption of polar compounds in the course of acid dissolution of the carbonate matrix.
We present the results of the prompt, early and afterglow optical observations of five γ-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations were ...made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before the cessation of γ-ray emission, at 113 and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted in two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. A more detailed analysis of GRB 100901A and GRB 100906A, supplemented by Swift data, provides the following results and indicates different origins for the prompt optical radiation in the two bursts. The light-curve patterns and spectral distributions suggest that there is a common production site for the prompt optical and high-energy emission in GRB 100901A. The results of the spectral fits for GRB 100901A in the range from optical to X-ray favour power-law energy distributions and a consistent value of the optical extinction in the host galaxy. GRB 100906A produced a smoothly peaking optical light curve, suggesting that the prompt optical radiation in this GRB originated in a front shock. This is supported by a spectral analysis. We have found that the Amati and Ghirlanda relations are satisfied for GRB 100906A. We obtain an upper limit on the value of the optical extinction on the host of GRB 100906A.
The main stages in the creation of the Russian segment of the MASTER network of robotic telescopes is described. This network is designed for studies of the prompt optical emission of gammaray bursts ...(GRBs; optical emission synchronous with the gamma-ray radiation) and surveys of the sky aimed at discovering uncataloged objects and photometric studies for various programs. The first results obtained by the network, during its construction and immediately after its completion in December 2010, are presented. Eighty-nine alert pointings at GRBs (in most cases, being the first ground telescopes to point at the GRBs) were made from September 2006 through July 2011. The MASTER network holds first place in the world in terms of the total number of first pointings, and currently more than half of first pointings at GRBs by ground telescopes are made by the MASTER network. Photometric light curves of GRB 091020, GRB 091127, GRB 100901A, GRB 100906A, GRB 10925A, GRB 110106A, GRB 110422A, and GRB 110530A are presented. It is especially important that prompt emission was observed for GRB 100901A and GRB 100906A, and thar GRB 091127, GRB 110422A, and GRB 110106A were observed from the first seconds in two polarizations. Very-wide-field cameras carried out synchronous observations of the prompt emission of GRB 081102, GRB 081130B, GRB 090305B, GRB 090320B, GRB 090328, and GRB 090424. Discoveries of Type Ia supernovae are ongoing (among them the brightest supernova in 2009): 2008gy, 2009nr, 2010V, and others. In all, photometry of 387 supernovae has been carried out, 43 of which were either discovered or first observed with MASTER telescopes; more than half of these are Type Ia supernovae. Photometric studies of the open clusters NGC 7129 and NGC 7142 have been conducted, leading to the discovery of 38 variable stars. Sixty-nine optical transients have been discovered.
We report early optical linear polarization observations of two gamma-ray bursts made with the MASTER robotic telescope network. We found the minimum polarization for GRB 150301B to be 8 per cent at ...the beginning of the initial stage, whereas we detected no polarization for GRB 150413A either at the rising branch or after the burst reached the power-law afterglow stage. This is the earliest measurement of the polarization (in cosmological rest frame) of gamma-ray bursts. The primary intent of the paper is to discover optical emission and publish extremely rare (unique) high-quality light curves of the prompt optical emission of gamma-ray bursts during the non-monotonic stage of their evolution. We report that our team has discovered the optical counterpart of one of the bursts, GRB 150413A.
was to identify the most effective serum tumor markers for early diagnosis of hepatocellular carcinoma based on the combination of diagnostic characteristics and correlations.
There were observed 55 ...patients with chronic hepatitis C in the stage of liver cirrhosis with a verified diagnosis of hepatocellular carcinoma. The control group consisted of 55 patients with chronic hepatitis C at the stage of liver cirrhosis without hepatocellular carcinoma, comparable to the experimental group in terms of basic clinical profile. The following tumor markers were estimated in both groups: alpha-fetoprotein (AFP), alpha-fetoprotein-L3 (AFP-L3), annexin A2 (ANXA2), heparin-binding growth factor Midkine (MDK), glypican-3 (GPC3), des-gamma-carboxyprothrombin (DCP, PIVKA-II), dickkopf-related protein 1 (DKK-1), osteopontin (OPN), and Golgi protein 73 (GP73). There were also evaluated such indices as diagnostic sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio of a positive test, the possible correlation between alpha-fetoprotein and other tumor markers. The area under the ROC curve (AUC) was calculated at the 95% confidence interval.
The greatest sensitivity was revealed when using heparin-binding growth factor, annexin A2, osteopontin. Alpha-fetoprotein, alpha-fetoprotein-L3, glypican-3, des-gamma-carboxyprothrombin, dickkopf-related protein 1 had the best specificity. AUC>0.75 was found in annexin A2, heparin-binding growth factor, glypican-3, des-gamma-carboxyprothrombin, osteopontin, Golgi protein 73. The likelihood ratio of a positive test result was the highest for glypican-3. A significant correlation was found between alpha-fetoprotein and alpha-fetoprotein-L3, annexin A2, des-gamma-carboxyprothrombin.
According to the aggregate indicators of diagnostic efficiency, heparin-binding growth factor, glypican-3, and osteopontin are the most promising tumor markers of those studied. When they are used, integral AUC values are above the average, the level of these tumor markers in the blood of patients with hepatocellular cancer does not correlate with alpha-fetoprotein. They are applicable for diagnosing liver cancer in AFP-negative patients. The combined use of AFP + GPC3, AFP + OPN has already shown their advantages. However, the efficacy of the combination of AFP + MDK, GPC3 + OPN has not been determined yet; therefore, significance of the combined use of these tumor markers in the diagnosis of liver cancer should be investigated in the near future.
A nested cones type carbon nanofiber (CNF) was exposed to ball milling with different milling times. Ball milled CNFs were investigated by transmission electron microscopy, Raman spectroscopy, X-ray ...diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis. It was suggested that the milling energy could be consumed by CNF grinding and aggregating. The effect of mechanical stress causes a “flattening” of the CNFs with the loss of the nanofibrous structure, and the amount of carbon layers in crystallite decreases. Multiple structural changes induced by ball milling lead to fluctuations of sp
3/sp
2 and O/C ratios.
The results of a pilot application of a chemical composition for enhanced oil recovery developed at the IPC SB RAS are presented. The EOR-composition was tested in 2014 at the Permian-Carboniferous ...heavy oil deposit at the Usinskoye oil field. It is very effective for an increase in oil production rate and decrease in water cuttings of well production. In terms of the additionally produced oil, the resulting effect is up to 800 tons per well and its duration is up to 6 months. The application of technologies of low-productivity-well stimulation using the oil-displacing IKhNPRO system with controlled viscosity and alkalinity is thought to be promising. This composition is proposed for the cold’ stimulation of high-viscosity oil production as an alternative to thermal methods.
This paper considers latest highlights in simultaneous and follow-up optical observations of high energy astrophysical phenomena by MASTER Global Robotic Net. Such extreme Universe sources includes ...gamma-ray bursts, gravitational wave events, detected by LIGO/Virgo, fast radio bursts, high energy neutrino sources and others. Some of the neutrinos detected by ground-based facilities owe their births to supermassive black holes – blazars, which are in a special anxious state with high statistical reliability. We discovered the effect of a rapid decrease in the brightness of the blazar PKS 0735+17 at the time of the multiple detection of the high-energy neutrino event IceCube-211208A. This decrease in brightness within several hours was detected with a high confidence (SNR 10) in comparison with a multi-day brightening state of the blazar, which was accompanied not only by a maximum increase in the average brightness, but also by an increase in the amplitude of its brightness fluctuations. Additionally, we analyzed all cases of successful observation of blazars around neutrino events and obtained statistically reliable indications of the relationship between neutrino events and optical activity of blazars in the doubled error box at the 4.2
level.
We present the results of the prompt, early and afterglow optical observations of five gamma-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations ...were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before the cessation of gamma-ray emission, at 113 and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted in two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. A more detailed analysis of GRB 100901A and GRB 100906A, supplemented by Swift data, provides the following results and indicates different origins for the prompt optical radiation in the two bursts. The light-curve patterns and spectral distributions suggest that there is a common production site for the prompt optical and high-energy emission in GRB 100901A. The results of the spectral fits for GRB 100901A in the range from optical to X-ray favour power-law energy distributions and a consistent value of the optical extinction in the host galaxy. GRB 100906A produced a smoothly peaking optical light curve, suggesting that the prompt optical radiation in this GRB originated in a front shock. This is supported by a spectral analysis. We have found that the Amati and Ghirlanda relations are satisfied for GRB 100906A. We obtain an upper limit on the value of the optical extinction on the host of GRB 100906A. PUBLICATION ABSTRACT
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