The Formation of the Structure and Tribological Properties of Composite Bronzes Reinforced with Steel Dendrites

The possibility of creating of composite bronzes reinforced with steel dendrites from martensitic, austenitic and ferritic steels was considered. Compared to the BrO10 bronze widely used in the sliding friction units, bronze BRZHNA 12-7-1 has an increased complex of mechanical, technological and, especially, tribological properties. At comparable values of the friction coefficient, the wear resistance of bronze BRZHNA 12-7-1 is much higher. In contrast to the classic BrO10 bronze, composite bronze can be obtained in a hot-deformed state, welded, welded on steel and cast iron. The level of mechanical properties: σ0.2 = 220 MPa;

Millimeter wave spectroscopy of the ground, first and second excited torsional states of acetone

Purpose: spectrum investigation of the lowest three torsional states of acetone ( CH₃COCH₃ ) within the frequency ranges 34–150 and 480–620 GHz.Предмет и цель работы: исследование спектра первых трех торсионных состояний ацетона (CH₃COCH₃ ) в диапазонах 34÷150 и 480 ÷ 620 ГГц.Предмет і мета роботи: дослідження спектра перших трьох торсійних станів ацетону (CH₃COCH₃ ) у діапазонах 34 - 150 та 480 - 620 ГГц

Intertorsional Interactions Revealing Absolute Configurations: The V6 Internal Rotation Heavy-Top Case of Benzotrifluoride

We report the microwave spectroscopic signatures of multiple torsional states of the CF3 internal rotation in benzotrifluoride (,,-trifluorotoluene). We could observe individual rotational transitions in a total of 8 different torsional states, a quite challenging task for heavy tops even with Fourier transform microwave techniques. Accidental mixings of m=0 and m = 3 torsional states as well as m=1 and m=2 torsional states, which can complicate the assignment of the spectra severely, have been observed. These accidental mixings are probably systematic for molecules with heavy tops exhibiting an almost free internal rotation and give an opportunity to determine the sign in the (1/2)V6 (1  cos6) potential function hindering internal rotation and in consequence the orientation of the CF3 top versus C6H5 frame. A recently developed torsion-rotation program reproduces all line positions within the experimental accuracy of about 2.0 kHz. The V6 barrier has been determined to be 3.229949(32) cm-1. The corresponding torsional spacings could be determined with the seven digits accuracy underlying the supersonic-jet Fourier transform microwave (FTMW) techniqu

Effect of production methods on tribological characteristics of babbitt coatings

The authors have studied variations in such tribological characteristics as the friction coefficient and wear rate of babbitt coatings obtained by the methods of turbulent casting, gas surfacing, plasma spraying, and activated arc metallization. The results obtained are discussed from the standpoints of microstructural metallographic analysis. © 2012 Allerton Press, Inc

The rotational spectrum of Methylarsine

International audienceThe rotational spectrum of an organoarsenic compound, methylarsine, CH3AsH2, was studied in the frequency range 10–80 GHz using the Stark-modulated spectrometer in Oslo, and in the frequency range 150–660 GHz using the Lille spectrometer. The experimental work was augmented by high-level ab initio calculations. The analysis of large amplitude torsional motion in CH3AsH2 was performed using the rho axis method and the RAM36 code modified to take into account the nuclear quadrupole hyperfine structure. The final fit used 48 parameters (including 3 parameters of quadrupole coupling) to give an overall unitless root-mean-square deviation of 0.92 for the dataset consisting of 2753, 991, and 414 transitions belonging, respectively, to the ground, first, and second excited torsional states. Compact grouping of rotational transitions due to the small asymmetry (κ=-0.9986), torsional splittings due to internal rotation of the CH3 group, and relatively large hyperfine splittings due to a rather large value of the arsenic nuclear quadrupole moment (χaa=35.4 MHz, χcc=−117.2 MHz, χac=115.7 MHz) represent an interesting case of interplay of different splittings in a molecule with a rather strong coupling between internal and overall rotations (ρ=0.413)

Submillimeter wave spectroscopy of propanoic acid (CH3CH2COOH) and its ISM search

This paper makes use of the following ALMA data: ADS/JAO.ALMA⧹2011.0.00009.SV. (https://almascience.nrao.edu/asax/)International audienceThree compounds with a C3H6O2 formula have been detected in the Interstellar Medium (ISM): ethyl formate (CH3CH2OC(O)H), methyl acetate (CH3OC(O)CH3) and very recently hydroxyacetone (CH3C(O)CH2OH). The higher thermodynamic stability of another isomer, the propanoic acid (CH3CH2C(O)OH), clearly suggests that this molecule should be considered as a possible candidate for ISM detection. To provide reliable predictions for astronomical use in the millimeter and submillimeter wave ranges we performed a new study of propanoic acid rotational spectrum up to 545 GHz. The analysis of large amplitude methyl top torsional motion in this molecule was carried out using the rho axis method and the RAM36 program code. More than 3200 lines corresponding to the rotational transitions in the ground and first excited methyl top torsional states were newly assigned and fit within experimental error. This enabled us to produce new predictions which were used to search for propanoic acid in two high-mass star-forming regions: SgrB2 (public IRAM 30 m) and Orion KL (ALMA Science Verification). We report a non-detection of propanoic acid in these clouds and derive upper limits to the column density

Submillimeter wave spectroscopy of propanoic acid (CH3CH2COOH) and its ISM search

8 pags., 3 figs., 3 tabs.Three compounds with a CHO formula have been detected in the Interstellar Medium (ISM): ethyl formate (CHCHOC(O)H), methyl acetate (CHOC(O)CH) and very recently hydroxyacetone (CHC(O)CHOH). The higher thermodynamic stability of another isomer, the propanoic acid (CHCHC(O)OH), clearly suggests that this molecule should be considered as a possible candidate for ISM detection. To provide reliable predictions for astronomical use in the millimeter and submillimeter wave ranges we performed a new study of propanoic acid rotational spectrum up to 545 GHz. The analysis of large amplitude methyl top torsional motion in this molecule was carried out using the rho axis method and the RAM36 program code. More than 3200 lines corresponding to the rotational transitions in the ground and first excited methyl top torsional states were newly assigned and fit within experimental error. This enabled us to produce new predictions which were used to search for propanoic acid in two high-mass star-forming regions: SgrB2 (public IRAM 30 m) and Orion KL (ALMA Science Verification). We report a non-detection of propanoic acid in these clouds and derive upper limits to the column density.LM/RAM/JCG acknowledge the support of the Programme National “Physique et Chimie du Milieu Interstellaire” (PCMI) of CNRS/INSU. JCG thanks also the Centre National d’Etudes Spatiales (CNES) for a grant. BT and JC thank Ministerio de Ciencia e Innovaci ́on of Spain (MICIU) for funding support through projects AYA2016-75066-C2-1-P, PID2019-106110 GB-I00, PID2019-107115 GB-C21/ AEI/ 10.13039/ 501100011033, and PID2019-106235 GB-I00. We also thank ERC for funding through grant ERC2013-Syg-610256-NANOCOSMOS. This paper makes use of the following ALMA data: ADS/JAO. ALMA⧹♯2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) with NRC (Canada), NSC, and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This work was also based on observations carried out with the IRAM 30-meter telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain