Effect of temperature and atmospheric pressure on methane (CH4) ebullition from near-surface peats

At atmospheric pressure, inactivation of lactoperoxidase (LPO) in milk and whey was studied in a temperature range of 69–73 °C and followed first order kinetics. Temperature dependence of the first order inactivation rate constants could be accurately described by the Arrhenius equation, with an activation energy of 635·3±70·7 kJ/mol for raw bovine milk and 736·9±40·9 kJ/mol for diluted whey, indicating a very high temperature sensitivity. On the other hand, LPO is very pressure resistant and not or only slightly affected by treatment at pressure up to 700 MPa combined with temperatures between 20 and 65 °C. Both for thermal and pressure treatment, stability of LPO was higher in milk than in diluted whey. Besides, a very pronounced antagonistic effect between high temperature and pressure was observed, i.e. at 73 °C, a temperature where thermal inactivation at atmospheric pressure occurs rapidly, application of pressure up to 700 MPa exerted a protective effect. At atmospheric pressure, LPO in diluted whey was optimally active at a temperature of about 50 °C. At all temperatures studied (20–60 °C), LPO remained active during pressure treatment up to 300 MPa, although the activity was significantly reduced at pressures higher than 100 MPa. The optimal temperature was found to shift to lower values (30–40 °C) with increasing pressure.

Download Full-text

Effect of Temperature Extraction on the Potassium and Calcium Content in the Lemon and Orange Water Peel Extracts

JOURNAL OF ADVANCES IN CHEMISTRY ◽

10.24297/jac.v17i.8714 ◽

2020 ◽

Vol 17 ◽

pp. 35-43

Author(s):

Amra Bratovcic

Keyword(s):

Atmospheric Pressure ◽

Calcium Content ◽

Effect Of Temperature ◽

Proper Function ◽

Photometric Method ◽

Electrolyte Balance ◽

Distilled Water ◽

Fruit Peel ◽

Water And Electrolyte Balance ◽

Extraction Mixture

The aim of this study is to examine the effect of temperature extraction on the potassium (K) and calcium (Ca) contents in orange and lemon peel extracts. The extractions were done at 62 ºC and 92 °C for 15 minutes and atmospheric pressure in distilled water. The fruit peel content in the extraction mixture was 5 % (w/v) in all samples. Calcium (Ca) and potassium (K) concentrations have been determined by flame photometric method. This research has revealed that by increasing the temperature of extraction, in particular, the concentration of Ca and K concentrations increased as applied extraction temperatures increased. The concentration of potassium is higher than the concentration of calcium in orange and lemon extracts, respectively. The concentration of K was 308 mg/l at 62 ºC and 361 mg/l at 92 ºC in lemon extracts, while in orange extracts the concentration of K was 476 mg/l at 62 ºC and 483 mg/l at 92 ºC. The concentration of Ca was 70.8 mg/l at 62 ºC and 71.9 mg/l at 92 ºC in lemon extracts, while in orange extracts the concentration of Ca was 91 mg/l at 62 ºC and 93.6 mg/l at 92 ºC. These results confirm that both citrus could be a very valuable source of potassium and calcium which are needed micronutrients to ensure the water and electrolyte balance and to build and maintain strong bones, proper function of muscles and nerves.

Download Full-text

Investigation of Ni catalyst activation during plasma-assisted methane oxidation

Journal of Physics D Applied Physics ◽

10.1088/1361-6463/ac4724 ◽

2021 ◽

Author(s):

Yudong Li ◽

Michael Hinshelwood ◽

Gottlieb S Oehrlein

Keyword(s):

Fourier Transform ◽

Atmospheric Pressure ◽

Atmospheric Pressure Plasma ◽

Surface Region ◽

Operating Conditions ◽

Ni Catalyst ◽

Plasma Catalysis ◽

Catalyst Activation ◽

Near Surface ◽

Pressure Plasma

Abstract Atmospheric pressure plasma has shown promise in improving thermally activated catalytic reactions through a process termed plasma-catalysis synergy. In this work, we investigated atmospheric pressure plasma jet (APPJ)-assisted CH4 oxidation over a Ni/SiO2.Al2O3 catalyst. Downstream gas-phase products from CH4 conversion were quantified by Fourier transform infrared spectroscopy (FTIR). The catalyst near-surface region was characterized by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The catalyst was observed to be activated at elevated temperature (500 °C) if it was exposed to the APPJ operated at large plasma power. “Catalyst activation” signifies that the purely thermal conversion of CH4 using catalysts which had been pre-exposed to plasma became more intense and produced consistently CO product, even if the plasma was extinguished. Without the application of the APPJ to the Ni catalyst surface this was not observed at 500 °C. The study of different exposure conditions of the activated catalyst indicates that the reduction of the catalyst by the APPJ is likely the cause of the catalyst activation. We also observed a systematic shift of the vibrational frequency of adsorbed CO on Ni catalyst when plasma operating conditions and catalyst temperatures were varied and discussed possible explanations for the observed changes. This work provides insights into the plasma-catalyst interaction, especially catalyst modification in the plasma catalysis process, and potentially demonstrates the possibility of utilizing the surface CO as a local probe to understand the plasma-catalyst interaction and shed light on the complexity of plasma catalysis.

Download Full-text

The Effect of Temperature and Si Concentration on the Mixing of AlAs/GaAs Superlattices

MRS Proceedings ◽

10.1557/proc-77-743 ◽

1986 ◽

Vol 77 ◽

Author(s):

Ping Mei ◽

H. W. Yoon ◽

T. Venkatesan ◽

S. A. Schwarz ◽

J. P. Harbison

Keyword(s):

Activation Energy ◽

Molecular Beam ◽

Secondary Ion Mass Spectrometry ◽

Diffusion Length ◽

Dopant Concentration ◽

Effect Of Temperature ◽

Surface Layers ◽

Near Surface ◽

Depth Profiles ◽

Secondary Ion

ABSTRACTThe intermixing of AlAs/GaAs superlattices has been investigated as a function of Si concentration following anneals in the range of 500 to 900 C. The superlattice samples were grown by molecular beam epitaxy(MBE) and the near surface layers were doped with silicon at concentrations of 2×10 to 5×1018 cm-3. Si and Al depth profiles were measured with secondary ion mass spectrometry (SIMS).The diffusion length and activation energy of Al as a function of silicon dopant concentration are derived from the SIMS data. In the temperature range studied an activation energy for the Al interdiffusion of -4eV is observed with the diffusion coefficients increasing rapidly with Si concentration.

Download Full-text

Effect of temperature on thermal (density), caloric (heat capacity), acoustic (speed of sound) and transport (viscosity) properties of 1-octyl-3-methylimidazolium hexafluorophosphate at atmospheric pressure

The Journal of Chemical Thermodynamics ◽

10.1016/j.jct.2018.04.018 ◽

2018 ◽

Vol 124 ◽

pp. 49-64 ◽

Cited By ~ 5

Author(s):

Javid Safarov ◽

Christoffer Bussemer ◽

Abilgani Aliyev ◽

Carlos Lafuente ◽

Egon Hassel ◽

...

Keyword(s):

Heat Capacity ◽

Speed Of Sound ◽

Atmospheric Pressure ◽

Effect Of Temperature ◽

Acoustic Speed

Download Full-text

Effect of Temperature on the Deformation Behavior of Copper Nickel Alloys under Sliding

Materials ◽

10.3390/ma14010060 ◽

2020 ◽

Vol 14 (1) ◽

pp. 60

Author(s):

Stefan J. Eder ◽

Philipp G. Grützmacher ◽

Manel Rodríguez Ripoll ◽

Daniele Dini ◽

Carsten Gachot

Keyword(s):

Microstructural Evolution ◽

Large Scale ◽

Mechanical Energy ◽

Normal Pressure ◽

Effect Of Temperature ◽

Near Surface ◽

Dislocation Activity ◽

Deformation Response ◽

Sliding Interface ◽

Dynamics Simulations

The microstructural evolution in the near-surface regions of a dry sliding interface has considerable influence on its tribological behavior and is driven mainly by mechanical energy and heat. In this work, we use large-scale molecular dynamics simulations to study the effect of temperature on the deformation response of FCC CuNi alloys of several compositions under various normal pressures. The microstructural evolution below the surface, marked by mechanisms spanning grain refinement, grain coarsening, twinning, and shear layer formation, is discussed in depth. The observed results are complemented by a rigorous analysis of the dislocation activity near the sliding interface. Moreover, we define key quantities corresponding to deformation mechanisms and analyze the time-independent differences between 300 K and 600 K for all simulated compositions and normal pressures. Raising the Ni content or reducing the temperature increases the energy barrier to activate dislocation activity or promote plasticity overall, thus increasing the threshold stress required for the transition to the next deformation regime. Repeated distillation of our quantitative analysis and successive elimination of spatial and time dimensions from the data allows us to produce a 3D map of the dominating deformation mechanism regimes for CuNi alloys as a function of composition, normal pressure, and homologous temperature.

Download Full-text