scholarly journals Long-Term Dissolution of Glass Fibers in Water Described by Dissolving Cylinder Zero-Order Kinetic Model: Mass Loss and Radius Reduction

2018 ◽  
Vol 16 (1) ◽  
pp. 1189-1199 ◽  
Author(s):  
Andrey E. Krauklis ◽  
Andreas T. Echtermeyer
Keyword(s):  
Steady State ◽  
Mass Loss ◽  
Rate Constants ◽  
Total Mass ◽  
Glass Fibers ◽  
Zero Order ◽  
Order Kinetic ◽  
Total Mass Loss ◽  
Fiber Radius

AbstractGlass fibers are degraded when they are exposed to water. In this work, a model is developed that uses zero-order kinetics for predicting a decreasing glass fiber radius. The model is used to describe experimental test results of almost half a year long-term dissolution of R-glass fibers. The model is able to predict both mass loss and radius reduction kinetics using the same four parameters: initial fiber radius (r0), rate constants for both short-term degradation $\left( K_{0}^{I} \right)$and steady-state degradation $\left( K_{0}^{II} \right)$and the time when steady-state kinetics are reached (tst). All parameters can be easily determined from initial radius measurements and mass loss evolution in time. Elements released and detected during degradation were Na, K, Ca, Mg, Fe, Al, Si and Cl. Rate constants were obtained for individual ion release and for the total mass loss. The contribution of Si to the total mass loss was the largest (56.1% by mass). It governed the dissolution process. The kinetics of radius reduction are also reported. The radius reduction was found to be linear with time during the steady-state dissolution. The zero-order kinetic constant and the density of the glass describe the rate (proportionality) of the dissolution.

Leaching of Am-241 from a Radioactive Waste Glass Corroded in the Presence of Stainless Steel Corrosion Products and/or Bentonite

1987 ◽  
Vol 112 ◽  
Author(s):  
Masaki Tsukamoto ◽  
Inga-Kari Björner ◽  
Hilbert Christensen ◽  
Hans-Peter Hermansson ◽  
Lars Werme
Keyword(s):  
Stainless Steel ◽  
Radioactive Waste ◽  
Mass Loss ◽  
Total Mass ◽  
Corrosion Behaviour ◽  
Steel Corrosion ◽  
Waste Glass ◽  
Corrosion Products ◽  
Total Mass Loss ◽  
Elemental Mass

AbstractThe release of Am-241 during corrosion of the radioactive waste glass, JSS-A, has been studied in the presence of corrosion products and/or uncom-pacted bentonite. The corrosion behaviour of Am-241 has been analyzed using gamma spectrometry. Adsorption of Am-241 on bentonite is observed in all cases. The contents of Am-241 in centrifuged leachates are in most cases less than 1/100 of total values. The normalized elemental mass loss of Am increases initially with corrosion time, and the values in the presence of bentonite and corrosion products are larger than those in the presence of bentonite alone. This tendency is in agreement with results previously found for other elements. The release of Am is low, only about 10–20 % of the corresponding total mass loss.

Nitrogen removal characteristics of nitrification and denitrification filters

1994 ◽  
Vol 29 (10-11) ◽  
pp. 409-416 ◽  
Author(s):  
F. Çeçen ◽  
I. E. Gönenç
Keyword(s):  
Nitrogen Removal ◽  
Rate Constants ◽  
Order Rate Constant ◽  
Zero Order ◽  
Ammonia Removal ◽  
Nitrite Accumulation ◽  
Order Kinetic ◽  
Order Rate ◽  
In Series ◽  
Nitrification And Denitrification

The kinetics of nitrogen removal was studied in upflow submerged nitrification and denitrification filters in series. Nitrification followed first-, half-, and zero-order kinetics. For the half-order range the half-order rate constant was about 0.9gNH4-N1/2m−1/2d−1. The zero-order rate constants for the DO ranges of 2-3 mg/L and 4-5 mg/L were found as 0.47 gNH4-Nm−2d−1 and 1.82 gNH4-Nm−2d−1, respectively. In the zero-order region ammonia removal proceeded as a half-order reaction in oxygen concentration and the half-order rate constants were about 1.4-2.7 gO21/2m−1/2d−1. Nitrite accumulation reached a considerable degree at bulk oxygen to bulk ammonia ratios lower than 5 since the formation of nitrate was inhibited. Similar to nitrification half- and zero-order kinetic regions were also observed in denitrification. The half- and zero-order rate constants for carbon unlimited cases (influent COD/NOx-N>5) were about 0.23 gNOx-N1/2m−1/2d−1 and 1.9 gNOx-Nm−2d−1, respectively. The nitrite produced in the nitrification stage could be reduced in denitrification. The removal kinetics in the presence of nitrite was found to be similar to the kinetics when the influent consisted of nitrate only.

Dose-Rate Dependence of Radiation Damage in Polymers

1998 ◽  
Vol 4 (S2) ◽  
pp. 800-801
Author(s):  
R.F. Egerton ◽  
I. Rauf
Keyword(s):  
Energy Loss ◽  
Mass Loss ◽  
Dose Rate ◽  
Radiation Damage ◽  
Total Mass ◽  
Room Temperature ◽  
Low Loss ◽  
Total Mass Loss ◽  
Diffraction Patterns ◽  
Accumulated Dose

Three aspects of radiation damage are of concern to electron microscopists: changes in crystallographic or molecular structure, mass loss and change in chemical composition. Structural change can be monitored from the fading of diffraction patterns or from loss of fine structure in an energy-loss spectrum. Total mass loss, in the form of a reduction in inelastic-scattering power, can be observed from the low-loss spectrum. Mass loss can also be monitored from energy-loss ionization edges, with the advantage that the loss of particular elements can be studied separately. It is possible to assign a characteristic dose De for the disappearance of a particular element.At room temperature, the amount of damage usually depends on the accumulated dose (exposure) but not on the dose rate (current density). However, cooling the specimen tends to reduce mass loss, probably because of the reduced diffusion coefficients.

scholarly journals Wintertime storage of water in buried supraglacial lakes across the Greenland Ice Sheet

2014 ◽  
Vol 8 (4) ◽  
pp. 3999-4031 ◽  
Author(s):  
L. S. Koenig ◽  
D. J. Lampkin ◽  
L. N. Montgomery ◽  
S. L. Hamilton ◽  
J. B. Turrin ◽  
...  
Keyword(s):  
Mass Loss ◽  
Total Mass ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Subsurface Water ◽  
Blue Color ◽  
Total Mass Loss ◽  
Supraglacial Lakes ◽  
Hydrologic System ◽  
Surface Melt

Abstract. Surface melt over the Greenland Ice Sheet (GrIS) is increasing and estimated to account for half or more of the total mass loss. Little, however, is known about the hydrologic pathways that route surface melt within the ice sheet. In this study, we present over-winter storage of water in buried supraglacial lakes as one hydrologic pathway for surface melt, referred to as buried lakes. Airborne radar echograms are used to detect the buried lakes that are distributed extensively around the margin of the GrIS. The subsurface water can persist through multiple winters and is, on average, ~4.2 + 0.4 m below the surface. The few buried lakes that are visible at the surface of the GrIS have a~unique visible signature associated with a darker blue color where subsurface water is located. The volume of retained water in the buried lakes is likely insignificant compared to the total mass loss from the GrIS but the water will have important implications locally for the development of the englacial hydrologic network, ice temperature profiles and glacial dynamics. The buried lakes represent a small but year-round source of meltwater in the GrIS hydrologic system.

scholarly journals Wintertime storage of water in buried supraglacial lakes across the Greenland Ice Sheet

2015 ◽  
Vol 9 (4) ◽  
pp. 1333-1342 ◽  
Author(s):  
L. S. Koenig ◽  
D. J. Lampkin ◽  
L. N. Montgomery ◽  
S. L. Hamilton ◽  
J. B. Turrin ◽  
...  
Keyword(s):  
Mass Loss ◽  
Total Mass ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Expression ◽  
Subsurface Water ◽  
Blue Color ◽  
Total Mass Loss ◽  
Supraglacial Lakes ◽  
Hydrologic System

Abstract. Increased surface melt over the Greenland Ice Sheet (GrIS) is now estimated to account for half or more of the ice sheet's total mass loss. Here, we show that some meltwater is stored, over winter, in buried supraglacial lakes. We use airborne radar from Operation IceBridge between 2009 and 2012 to detect buried supraglacial lakes, and we find that they were distributed extensively around the GrIS margin through that period. Buried supraglacial lakes can persist through multiple winters and are, on average, ~ 1.9 + 0.2 m below the surface. Most buried supraglacial lakes exist with no surface expression of their occurrence in visible imagery. The few buried supraglacial lakes that do exhibit surface expression have a unique visible signature associated with a darker blue color where subsurface water is located. The volume of retained water in the buried supraglacial lakes is likely insignificant compared to the total mass loss from the GrIS, but the water may have important implications locally for the development of the englacial hydrologic system and ice temperatures. Buried supraglacial lakes represent a small but year-round source of meltwater in the GrIS hydrologic system.

scholarly journals Longbasaba Glacier recession and contribution to its proglacial lake volume between 1988 and 2018

2021 ◽  
pp. 1-12
Author(s):  
Junfeng Wei ◽  
Shiyin Liu ◽  
Xin Wang ◽  
Yong Zhang ◽  
Zongli Jiang ◽  
...  
Keyword(s):  
Mass Loss ◽  
Total Mass ◽  
Water Volume ◽  
Total Mass Loss ◽  
Lake Volume ◽  
Glacier Recession ◽  
Proglacial Lakes ◽  
Proglacial Lake ◽  
Near Future ◽  
The Himalaya

Abstract During the last few decades, the lake-terminating glaciers in the Himalaya have receded faster than the land-terminating glaciers as proglacial lakes have exacerbated the mass loss of their host glaciers. Monitoring the impacts of glacier recession and dynamics on lake extent and water volume provides an approach to assess the mass interplay between glaciers and proglacial lakes. We describe the recession of Longbasaba Glacier and estimate the mass wastage and its contribution to the water volume of its proglacial lake. The results show that the glacier area has decreased by 3% during 1988–2018, with a more variable recession prior to 2008 than in the last decade. Longbasaba Lake has expanded by 164% in area and 237% in water volume, primarily as a result of meltwater inflow produced from surface lowering of the glacier. Over the periods 1988–2000 and 2000–18, the mass loss contributed by glacier thinning has decreased from 81 to 61% of the total mass loss, accompanied by a nearly doubled contribution from terminus retreat. With the current rate of retreat, Longbasaba glacier is expected to terminate in its proglacial lake for another four decades. The hazard risk of this lake is expected to continue to increase in the near future because of the projected continued glacier mass loss and related lake expansion.

scholarly journals To cool is to keep: residual H/He atmospheres of super-Earths and sub-Neptunes

2021 ◽  
Vol 503 (4) ◽  
pp. 5658-5674
Author(s):  
William Misener ◽  
Hilke E Schlichting
Keyword(s):  
Mass Loss ◽  
Time Scale ◽  
Total Mass ◽  
Equilibrium Temperature ◽  
Convective Boundary ◽  
First Order ◽  
Residual Hydrogen ◽  
Mean Molecular Weight ◽  
Exact Amount

ABSTRACT Super-Earths and sub-Neptunes are commonly thought to have accreted hydrogen/helium envelopes, consisting of a few to ten percent of their total mass, from the primordial gas disc. Subsequently, hydrodynamic escape driven by core-powered mass-loss and/or photoevaporation likely stripped much of these primordial envelopes from the lower mass and closer-in planets to form the super-Earth population. In this work, we show that after undergoing core-powered mass-loss, some super-Earths can retain small residual H/He envelopes. This retention is possible because, for significantly depleted atmospheres, the density at the radiative–convective boundary drops sufficiently such that the cooling time-scale becomes shorter than the mass-loss time-scale. The residual envelope is therefore able to contract, terminating further mass-loss. Using analytic calculations and numerical simulations, we show that the mass of primordial H/He envelope retained as a fraction of the planet’s total mass, fret, increases with increasing planet mass, Mc, and decreases with increasing equilibrium temperature, Teq, scaling as $f_\mathrm{ret} \propto M_\mathrm{c}^{3/2} T_\mathrm{eq}^{-1/2} \exp {[M_\mathrm{c}^{3/4} T_\mathrm{eq}^{-1}]}$. fret varies from <10−8 to about 10−3 for typical super-Earth parameters. To first order, the exact amount of left-over H/He depends on the initial envelope mass, the planet mass, its equilibrium temperature, and the envelope’s opacity. These residual hydrogen envelopes reduce the atmosphere’s mean molecular weight compared to a purely secondary atmosphere, a signature observable by current and future facilities. These remnant atmospheres may, however, in many cases be vulnerable to long-term erosion by photoevaporation. Any residual hydrogen envelope likely plays an important role in the long-term physical evolution of super-Earths, including their geology and geochemistry.

Kinetics of nonexchangeable potassium release from a Tropaquept as influenced by long-term cropping, fertilisation, and manuring

Soil Research ◽  
1999 ◽  
Vol 37 (2) ◽  
pp. 317 ◽  
Author(s):  
Ch. Srinivasa Rao ◽  
Anand Swarup ◽  
A. Subba Rao ◽  
V. Raja Gopal
Keyword(s):  
Rate Constants ◽  
Soil Samples ◽  
Continuous Cropping ◽  
Order Kinetic ◽  
Acid Media ◽  
First Order ◽  
Kinetics Of ◽  
K Release ◽  
Nonexchangeable Potassium

We studied the effect of long-term cropping, fertilisation, and manuring on kinetics of nonexchangeable potassium (K) release from a Tropaquept in 0·01 M CaCl2 and 0·01 M citric acid media under a rice–rice cropping system in an experiment started in 1971. Under continuous cropping, the cumulative K release from the soil decreased considerably in all treatments both with and without K application. The lowest K release from the nonexchangeable fraction of the soil was observed in the 100% optimum nitrogen+phosphorus (NP) treatment (55 and 34 mg/kg in 1980 and 1994, respectively), while the highest K release was in the 100% optimum NPK+farmyard manure (FYM) treatment (99 and 66 mg/kg in 1980 and 1994, respectively). Statistical analysis showed that a parabolic diffusion equation best described the K release from soil samples collected in 1980 (r = 0·989–0·992) and 1994 (r = 0·994–0·998), thereby indicating that the K release was a diffusion-controlled exchange. A first-order kinetic equation also explained K release behaviour from the soil samples in both years (r = 0·988 for 1980 and 0·971–0·988 for 1994 samples). The maximum and minimum values of rate constants were found for the 100% NPK+FYM and 100% NP treatments, respectively. A reduction in rate constants was observed with further cropping until 1994, with or without K supply, with the largest reduction being observed in the 100% NP treatment. Kinetic parameters of the first-order equation showed significant correlation with conventional measures of nonexchangeable K forms: 3 M H2SO4 and boiling 1 M HNO3 extractable K. From these results it is concluded that continuous cropping without K inputs through fertilisers or manure caused a decline in nonexchangeable K reserves and release rate while application of recommended NPK plus FYM maintained higher release rates.

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