Friction-induced vibration of a slider-on-rotating-disc system considering uniform and non-uniform friction characteristics with bi-stability

Crystal growth rates of copper sulphate pentahydrate (CuSO4.5 H2O) determined by different authors and methods are compared. The methods included in this comparison are: (i) Measurement on a fixed crystal suspended in a streaming solution, (ii) measurement on a rotating disc, (iii) measurement in a fluidized bed, (iv) measurement in an agitated suspension. The comparison involves critical estimation of the supersaturation used in measurements, of shape factors used for data treatment and a correction for the effect of temperature. Conclusions are drawn for the choice of values to be specified when data of crystal growth rate measurements are published.

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Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19892951 ◽

1989 ◽

Vol 54 (11) ◽

pp. 2951-2961 ◽

Cited By ~ 2

Author(s):

Miloslav Karel ◽

Jaroslav Nývlt

Keyword(s):

Growth Rate ◽

Single Crystal ◽

Single Crystals ◽

Growth Rates ◽

Diffusion Coefficients ◽

Preferred Orientation ◽

Rotating Disc ◽

Dissolution Rates ◽

Rates Of Growth ◽

Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

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Combination of Thermal, Hydrometallurgical and Electrochemical Tannery Waste Treatment for Cr(III) Recovery

Applied Sciences ◽

10.3390/app11020532 ◽

2021 ◽

Vol 11 (2) ◽

pp. 532

Author(s):

Evgenios Kokkinos ◽

Aggeliki Banti ◽

Ioanna Mintsouli ◽

Aikaterini Touni ◽

Sotiris Sotiropoulos ◽

...

Keyword(s):

Extraction Efficiency ◽

Waste Treatment ◽

Constant Current ◽

Vitreous Carbon ◽

Applied Potential ◽

Disc Electrode ◽

Rotating Disc ◽

Reduction Efficiency ◽

Scale Reactor ◽

Initial Conversion

A combination of thermal (500–750 °C in air) and hydrometallurgical (acidic) treatments have been applied to dried tannery sludge, resulting in the initial conversion of Cr(III) to Cr(VI) and its subsequent leaching as wastewater with high Cr(VI) concentration content (3000–6000 mg/L), presenting an extraction efficiency over 90%. The optimal electrochemical conditions for the subsequent Cr(VI) reduction with respect to acid concentration and acid kind were established by applying appropriate rotating disc electrode (RDE) experiments, using a glassy carbon (GC) electrode, and found to be equal or higher than 0.5 M H2SO4 (for the respective Cr(III) concentration range studied). The result from leaching Cr(VI) wastewater was further treated in small electrochemical bench-scale reactor for its conversion back to Cr(III) form, potentially reusable in the tanning industry. Ti-based anodes and a reticulated vitreous carbon (RVC) cathode were used to treat small (350–800 mL) samples in batch, as well as in batch-recirculation prototype electrochemical reactors, under the application of constant current or appropriately applied potential to achieve Cr(VI) conversion/reduction efficiency over 95%.

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Principal component analysis tomography in near-infrared integral field spectroscopy of young stellar objects – I. Revisiting the high-mass protostar W33A

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab358 ◽

2021 ◽

Vol 503 (1) ◽

pp. 270-291

Author(s):

F Navarete ◽

A Damineli ◽

J E Steiner ◽

R D Blum

Keyword(s):

Large Scale ◽

Near Infrared ◽

Rotation Axis ◽

Principal Component ◽

Young Stellar Objects ◽

High Mass ◽

Continuum Emission ◽

Rotating Disc ◽

Stellar Objects ◽

K Band

ABSTRACT W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the K-band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position–velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1 arcsec (∼250 au) from the central source, suggesting a structure about four times more compact than previously reported. We derived a dynamical mass of 10.0$^{+4.1}_{-2.2}$ $\rm {M}_\odot$ for the ‘disc + protostar’ system, about ∼33 per cent smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H2 wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ∼63 mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (Source B) was also identified in the NIFS field of view as a faint point-like object at a projected distance of ∼7000 au from W33A, powering extended K-band continuum emission detected in the same field. Another source (Source C) is driving a bipolar $\rm {H}_2$ jet aligned perpendicular to the rotation axis of W33A.

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