108 research outputs found

    Some Remarks on Combining Forms in English-Japanese Dictionaries

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    © 2016, Pleiades Publishing, Inc.Previously unknown isononylcalix[8]arene was synthesized from commercially available isononylphenol. The properties of the product (solubility, extraction ability, tendency to aggregation) were compared with those of the known tert-butylcalix[8]arene. The extraction of 137Cs, 99mTc, and 241Am from alkaline carbonate solutions with solutions of p-alkylcalix[8]arenes (alkyl = tert-butyl, isononyl) in tetrachloroethylene was studied. The dependence of the distribution ratios on pH of the aqueous phase in the interval from 11 to 13.9 and on the nature of functional groups in the calixarene core was determined. The composition of extractable solvates of cesium and americium with calix[8]arenes was found. Calix[8]arenes extract cesium from alkaline solutions more efficiently than p-tert-butylphenol, their nonmacrocyclic analog, does. tert-Butylcalix[8]arene exhibits the highest performance, which may be due to formation of aggregates 5.7 ± 0.8 nm in diameter in the organic phase at pH 13.5 of the aqueous phase. The isononyl derivative exists in the monomeric form (particle diameter 1.9 ± 0.5 nm)

    Numerical adiabatic potentials of orthorhombic Jahn-Teller effects retrieved from ultrasound attenuation experiments. Application to the SrF2:Cr crystal

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    A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propa- gation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60 K for the wave propagating along the [110] direction, for both the longitudinal and shear modes, the latter with two polarizations along the [001] and [110] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the ex- perimental findings is based on the T2g (eg +t2g) JTE problem including the linear and quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states.Comment: 8 pages, 3 figure

    Assessment of internal pressure effect, causing additional bending of the pipeline

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    Article justifies accounting for internal pressure effect in the pipeline, causing additional bending of the pipeline. According to some scientists, there is an erroneously used concept of the equivalent longitudinal axial force (ELAF) Sx, which depends on working pressure, temperature stresses, and joint deformations of pipelines with various types of soils. However, authors of the article use ELAF Sx concept at construction of mathematical model of stress-strain state (SSS) for complex section of the trunk pipeline, and also reveal it when analyzing the results of calculating the durability and stability of the pipeline. Analysis of SSS for calculated section of the pipeline was carried out for two statements of the problem for different values of operation parameters. In the first statement, effect of internal pressure causing bending of the pipeline is taken into account, and in the second it is neglected. It is shown that due to effect of ELAF Sx at p0 = 9.0 MPa, Dt = 29 °C extreme value of bend increases by 54 %, extreme values of bending stresses from span bending moment increase by 74 %, and extreme value of bending stresses from support bending moment double with regard to corresponding SSS characteristics of the pipeline. In case of neglecting the internal pressure effect causing additional bending of the pipeline (second statement of the problem), error in calculating the extreme value of bend is 35 %, extreme value of bending stresses from span bending moments is 44 %, and extreme value of bending stresses from support bending moments is 95 %

    Americium and cesium extraction from alkaline media by calix[8]arenes with p-tert-butyl and isononyl substituents on the upper rim: Aggregation effect

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    © ISUCT Publishing. The recovery of long-lived radionuclides from liquid radioactive wastes with subsequent immobilization and disposal significantly reduces radiological risks in the nuclear industry. At the Savannah River Site (USA), the functionalized calixarene bis(dimethyloctyl-oxy)calix[4]arenebenzocrown-6 (MaxCalix) was successfully used as selective extractant to separate cesium-137 from alkaline radioactive wastes. At the Mayak PA (Russia), the alkaline radioactive wastes include actinides, essentially americium, in addition to cesium-137, which also should be recovered. To separate cesium and americium from alkaline solutions, the simple tert-butylcalix[8] arene could be used, if it was not so poorly soluble in organic solvents. The aim of this study was to synthesize mixed p-alkylcalix[8] arenes with tert-butyl and isononyl groups taken at various ratios and to examine their applicability to extract cesium and americium from alkaline solutions. Starting from commercially available p-isononylphenol we have synthesized and characterized three mixed tert-butyl-isononylcalix[8] arenes with the tert-butyl to isononyl group ratio taken as 6:2, 4:4, and 2:6. The solubility of these mixed tert-butyl-isononylcalix[8]arenes in tetrachloroethylene ranges from 0.01 to 0.08 M, which is 3 to 8 times higher than that of p-tert-butylcalix[8] arene. The extraction of 137 Cs and 241 Am from alkaline-carbonate solutions with mixed p-alkylcalix[8]arenes in tetrachloroethylene was studied. For all the extractants, the maximal extraction of cesium and americium was observed in the pH range 13–14. Americium is extracted at lower pH since, unlike cesium, it forms very strong hydroxo complexes at high pH values. The composition of the solvates formed by the calixarenes with the radionuclides in the organic phase was determined using the equilibrium shift method (for trace amounts of the radionuclides) and the saturation method (extraction isotherm). The results obtained by the equilibrium shift method revealed dominant formation of solvates, in which the p-alkylcalix[8] arene binds 1–2 cations of cesium or americium. The saturation method suggests formation of solvates containing up to four cesium cations per an p-alkylcalix[8] arene molecule. Step-by-step substitution of the tert-butyl groups in p-alkylcalix[8] arene for the isononyl groups leads to decreasing extraction of both cesium and americium. For cesium, a small monotonic decrease in the extraction power of p-alkylcalix[8]arenes was observed: the difference in the distribution ratios between the tert-butyl and isononyl derivatives of calix[8] arene was less than two. The highest extractability of americium was observed with the mixed calix[8]arene containing two isononyl groups, and the difference in the distribution ratios was above 20. Interesting results were obtained when comparing the extraction of americium with freshly prepared and aged tetrachloroethylene solutions of the mixed calix[8] arene containing two isononyl groups. The americium distribution ratios obtained with the freshly prepared extractant was found to be lower by a factor of 4-5 as compared to the extractant aged for 15 h at +5 °C. The data obtained by the dynamic light scattering method indicate that, in freshly prepared solutions, the calix[8] arene occurs in a monomeric form, which transforms with time into large aggregates with a diameter of about 8 nm to form inverse micelles

    Cesium and americium extraction from carbonate-alkaline media with O-substituted p-alkylcalix[8]arenes

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    © 2017, Akadémiai Kiadó, Budapest, Hungary. 137 Cs and 241 Am extraction with perchloroethylene solutions of O-substituted p-alkylcalix[8]arenes (alkyl: tert-butyl, iso-nonyl) from carbonate-alkaline media is studied. Dependence of distribution ratios on pH values of the aqueous phase in the range 11–13.9 and on the nature of functional groups in the calixarene platform is confirmed. Composition of cesium and americium solvates with calix[8] arenes is determined. Tert-butylcalix[8]arene with oxybis(ethane-1,2-diyl) bridging group possesses superior efficiency towards cesium in alkaline media. The most efficient extractants for americium are “mixed” iso-nonyl-tert-butylcalix[8] arenes with ethane-1,2-diyl and oxybis(ethane-1,2-diyl) bridging groups

    Extraction of cesium and americium with p-alkylcalix[8]arenes from alkaline solutions

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    © 2016, Pleiades Publishing, Inc.Previously unknown isononylcalix[8]arene was synthesized from commercially available isononylphenol. The properties of the product (solubility, extraction ability, tendency to aggregation) were compared with those of the known tert-butylcalix[8]arene. The extraction of 137Cs, 99mTc, and 241Am from alkaline carbonate solutions with solutions of p-alkylcalix[8]arenes (alkyl = tert-butyl, isononyl) in tetrachloroethylene was studied. The dependence of the distribution ratios on pH of the aqueous phase in the interval from 11 to 13.9 and on the nature of functional groups in the calixarene core was determined. The composition of extractable solvates of cesium and americium with calix[8]arenes was found. Calix[8]arenes extract cesium from alkaline solutions more efficiently than p-tert-butylphenol, their nonmacrocyclic analog, does. tert-Butylcalix[8]arene exhibits the highest performance, which may be due to formation of aggregates 5.7 ± 0.8 nm in diameter in the organic phase at pH 13.5 of the aqueous phase. The isononyl derivative exists in the monomeric form (particle diameter 1.9 ± 0.5 nm)

    Effect of ionizing radiation on the extraction of Am(III) with p-tert-butylthiacalix[4]arene from alkaline carbonate solutions

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    © 2017, Pleiades Publishing, Inc. The effect of γ-irradiation of tert-butylthiacalix[4]arene (TCA) solutions in m-nitrobenzotrifluoride (NBTF) and tetrachloroethylene (TCE) on the extraction of 241 Am from alkaline carbonate solutions was studied. TCA itself remains stable upon γ-irradiation of its solutions in NBTF to a dose of 200 kGy, but the diluent undergoes strong degradation. The radiation resistance of TCA in TCE is considerably lower: A dose of 70 kGy causes complete degradat ion of TCA. In the TCA–TCE–aqueous phase system, sulfate ions appear upon γ-irradiation as the final product of the extractant radiolysis. A large number of γ-radiolysis products of TCE and TCA were detected by HPLC and GCMS. The products of radiolysis of TCA in TCE, compared to the initial extractant, have lower molecular mass and higher polarity. The results show that chlorinated diluents are not promising diluents for thiacalixarene in extraction processing of alkaline high-level waste

    Energy Release During Disk Accretion onto a Rapidly Rotating Neutron Star

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    The energy release L_s on the surface of a neutron star (NS) with a weak magnetic field and the energy release L_d in the surrounding accretion disk depend on two independent parameters that determine its state (for example, mass M and cyclic rotation frequency f) and is proportional to the accretion rate. We derive simple approximation formulas illustrating the dependence of the efficiency of energy release in an extended disk and in a boundary layer near the NS surface on the frequency and sense of rotation for various NS equations of state. Such formulas are obtained for the quadrupole moment of a NS, for a gap between its surface and a marginally stable orbit, for the rotation frequency in an equatorial Keplerian orbit and in the marginally stable circular orbit, and for the rate of NS spinup via disk accretion. In the case of NS and disk counterrotation, the energy release during accretion can reach 0.67M˙c20.67\dot{M}c^2. The sense of NS rotation is a factor that strongly affects the observed ratio of nuclear energy release during bursts to gravitational energy release between bursts in X-ray bursters. The possible existence of binary systems with NS and disk counterrotation in the Galaxy is discussed. Based on the static criterion for stability, we present a method of constructing the dependence of gravitational mass M on Kerr rotation parameter j and on total baryon mass (rest mass) m for a rigidly rotating neutron star. We show that all global NS characteristics can be expressed in terms of the function M(j, m) and its derivatives.Comment: 42 pages, 12 figures, to appear in Astronomy Letters, 2000, v.26, p.69

    The first TIPS surgery performed in the Udmurt Republic in a young patient with secondary biliary cirrhosis

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    Treatment of patients with iatrogenic injuries of the biliary tract is the most difficult and important section in hepatobiliary surgery. When analyzing the causes, it was found that in 70–94 % of cases this type of injury is observed during cholecystectomy. We present a rare clinical case of the development of secondary biliary cirrhosis due to iatrogenic trauma of the biliary tract. This injury caused long-term suffering for the patient due to the further development of complications of cirrhosis, specifically of portal hypertension. The latter caused repeated recurrent profuse bleeding from varicose veins of the esophagus. The use of a minimally invasive transjugular intrahepatic portosystemic shunt procedure for the first time in the Udmurt Republic was of particular relevance in solving this problem. This procedure has become a key one in solving the abovementioned problems and will become the preventive measure for the cirrhosis progression in the future. It is also important to focus on prophylactic measures aimed at preventing iatrogenic injuries of the biliary tract, as this problem can cause irreversible complications. Prevention should include adequate examination and visualization of the bile ducts and gallbladder before surgery, their careful mobilization, compliance with the rules of operation with electrosurgical instruments, as well as the use of additional minimally invasive techniques such as choledoscopy, cholangiography and intraoperative ultrasound. Besides that, all manipulations should be carried out under strict control and clear visualization of instruments and anatomical structures of organs. The article provides a detailed description of the technique of transjugular intrahepatic portosystemic shunt surgery, as well as presents X-ray images obtained during this operation

    A Model of Technical University Students’ Creative-Project Activities’ Systemic Commitment to Their Self-Development and the Experimental Verification of Its Effectiveness

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    The urgency of the need to develop a model of the systemic commitment of creative-project activity of technical university students to their self-development is due to the fact that the reserve possibilities of this type of teaching, research and professional activities from the perspective of the systemic commitment to self-development of the students’ competitiveness remain insufficiently investigated in the theory and practice of teacher education. In this regard, the article presents the main components of the model of systemic commitment of the creative-project activity of technical university students to their self-development, as well as the results for its implementation in practice of higher professional education. The presented components of the model in the article (objectives, contents, methods, learning and educational environment) are working for the ultimate goal − for self-development of professional creativity, self-development of the competitiveness of a student as a prospective specialist. The results of the article can be used by administrators and faculty members of higher education institutions. DOI: 10.5901/mjss.2015.v6n2s3p12
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