The Long-Term Corrosion and Modelling of Two Simulated Belgian Reference High-Level Waste Glasses - Part II

1989 ◽  
Vol 176 ◽  
Author(s):  
J. Patyn ◽  
P. Van Iseghem ◽  
W. Timmermans
Keyword(s):  
Pure Water ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
High Level Waste ◽  
Final State ◽  
Leach Rate ◽  
Enhanced Dissolution ◽  
High Level

ABSTRACTThe long term corrosion of two reference Belgian high-level waste glasses (SAN60 and SM58) were investigated in pure water. The corrosion was studied using powdered glass at a high surface area to volume ratio and temperatures of 90 and 120°C. The experimental data at 90°C reveal a “final” leach rate which decreases with time. At 120°C this “final” state is transient and followed by an enhanced dissolution, which was correlated with extensive surface crystallization. Modelling using the PHREEQE and GLASSOL computer codes described the initial corrosion, but was unable to account for the enhanced dissolution at 120°C.

Long-Term Release from High Level Waste Glass - Part IV: The Effect of Leaching Mechanism

1984 ◽  
Vol 44 ◽  
Author(s):  
Eberhard Freude ◽  
Bernd Grambow ◽  
Werner Lutze ◽  
Harald Rabe ◽  
Rodney C. Ewing
Keyword(s):  
Linear Time ◽  
High Surface ◽  
High Level Waste ◽  
Corrosion Mechanism ◽  
Surface Areas ◽  
One Year ◽  
The Stability ◽  
High Level ◽  
Long Term Behavior

During the past ten years extensive data have been determined for the corrosion of nuclear waste forms in short-term laboratory experiments (usually less than one year). The long-term behavior of glass has been inferred by: (1) the acceleration of corrosion rates at high temperatures [1]; (2) the use of high surface areas of the glass to small volumes of solution [1]; and the analysis of natural glasses altered over long periods of geologic time [2, 3]. The most recent efforts have concentrated on understanding the mechanisms of corrosion [1, 4, 5]. The corrosion mechanism may be used to make long-term extrapolations of the “stability” of the waste form. In this paper, we consider a linear time dependence for the corrosion under near saturation conditions and use a rate equation in the QTERM code [6, 7, 8] to model the long-term behavior of the German glass, C-31−3EC [9], JSS A [10, 11] and SRL TDS 131 [1]. The data base for C-31−3EC has been published elsewhere [9, 12, 13, 14], and we include experimental work completed by Rabe for boron and silica, at 200°C.

scholarly journals A Review of Electrospun Conductive Polyaniline Based Nanofiber Composites and Blends: Processing Features, Applications, and Future Directions

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Saiful Izwan Abd Razak ◽  
Izzati Fatimah Wahab ◽  
Fatirah Fadil ◽  
Farah Nuruljannah Dahli ◽  
Ahmad Zahran Md Khudzari ◽  
...  
Keyword(s):  
Technology Development ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Polymers And Plastics ◽  
Research Activities ◽  
Scaffold Materials ◽  
Conductive Polyaniline ◽  
Future Direction ◽  
High Level

Electrospun polymer nanofibers with high surface area to volume ratio and tunable characteristic are formed through the application of strong electrostatic field. Electrospinning has been identified as a straight forward and viable technique to produce nanofibers from polymer solution as their initial precursor. These nanofiber materials have attracted attention of researchers due to their enhanced and exceptional nanostructural characteristics. Electrospun polyaniline (PANI) based nanofiber is one of the important new materials for the rapidly growing technology development such as nanofiber based sensor devices, conductive tissue engineering scaffold materials, supercapacitors, and flexible solar cells applications. PANI however is relatively hard to process compared to that of other conventional polymers and plastics. The processing of PANI is daunting, mainly due to its rigid backbone which is related to its high level of conjugation. The challenges faced in the electrospinning processing of neat PANI have alternatively led to the development of the electrospun PANI based composites and blends. A review on the research activities of the electrospinning processing of the PANI based nanofibers, the potential prospect in various fields, and their future direction are presented.

Long-Term Radioactivity Release From Solidified High-Level Waste -Part I: An Approach To Evaluating Experimental Data

1981 ◽  
Vol 11 ◽  
Author(s):  
Friedrich K. Altenhein ◽  
Werner Lutze ◽  
Rodney C. Ewing
Keyword(s):  
Source Term ◽  
Elevated Temperatures ◽  
Relative Sensitivity ◽  
Reaction Rates ◽  
Waste Form ◽  
High Level Waste ◽  
Leach Rate ◽  
Leaching Experiments ◽  
High Level

Safety and risk analyses for the isolation of radioactive waste in a repository must begin with a source term to quantify the amount of radioactivity released from the waste form under a specific set of conditions. The interaction of the waste form with aqueous solutions is the most important mechanism to consider, as any material released may be dissolved and reach the biosphere. In this regard the behaviour of heat generating high-level waste is of particular importance, because reaction rates are higher at elevated temperatures. A long-term leach rate was derived from previous and continuing experimental work. The purpose of this paper is not to describe the “real case” release but rather to provide guidelines for the design of leaching experiments and determine the required precision for the data. This can be derived from the relative sensitivity of extrapolated leach rates for various parameters measured in laboratory experiments.

scholarly journals Electrospun Nanofibers for Sensing and Biosensing Applications—A Review

2021 ◽  
Vol 22 (12) ◽  
pp. 6357
Author(s):  
Kinga Halicka ◽  
Joanna Cabaj
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Toxic Metal ◽  
Volume Ratio ◽  
Electrospun Nanofibers ◽  
Clinical Diagnostics ◽  
Loading Capacity ◽  
Electrospun Nanofiber ◽  
Sensing Platforms ◽  
Different Types

Sensors and biosensors have found applications in many areas, e.g., in medicine and clinical diagnostics, or in environmental monitoring. To expand this field, nanotechnology has been employed in the construction of sensing platforms. Because of their properties, such as high surface area to volume ratio, nanofibers (NFs) have been studied and used to develop sensors with higher loading capacity, better sensitivity, and faster response time. They also allow to miniaturize designed platforms. One of the most commonly used techniques of the fabrication of NFs is electrospinning. Electrospun NFs can be used in different types of sensors and biosensors. This review presents recent studies concerning electrospun nanofiber-based electrochemical and optical sensing platforms for the detection of various medically and environmentally relevant compounds, including glucose, drugs, microorganisms, and toxic metal ions.

scholarly journals Design Considerations for Borehole Thermal Energy Storage (BTES): A Review with Emphasis on Convective Heat Transfer

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-26 ◽  
Author(s):  
Helge Skarphagen ◽  
David Banks ◽  
Bjørn S. Frengstad ◽  
Harald Gether
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Theoretical Calculations ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Thermal Recovery ◽  
Conductive Heat ◽  
Geological Environment

Borehole thermal energy storage (BTES) exploits the high volumetric heat capacity of rock-forming minerals and pore water to store large quantities of heat (or cold) on a seasonal basis in the geological environment. The BTES is a volume of rock or sediment accessed via an array of borehole heat exchangers (BHE). Even well-designed BTES arrays will lose a significant quantity of heat to the adjacent and subjacent rocks/sediments and to the surface; both theoretical calculations and empirical observations suggest that seasonal thermal recovery factors in excess of 50% are difficult to obtain. Storage efficiency may be dramatically reduced in cases where (i) natural groundwater advection through the BTES removes stored heat, (ii) extensive free convection cells (thermosiphons) are allowed to form, and (iii) poor BTES design results in a high surface area/volume ratio of the array shape, allowing high conductive heat losses. The most efficient array shape will typically be a cylinder with similar dimensions of diameter and depth, preferably with an insulated top surface. Despite the potential for moderate thermal recovery, the sheer volume of thermal storage that the natural geological environment offers can still make BTES a very attractive strategy for seasonal thermal energy storage within a “smart” district heat network, especially when coupled with more efficient surficial engineered dynamic thermal energy stores (DTES).

Recent trends in carbon nanotubes based prostate cancer therapy: A biomedical hybrid for diagnosis and treatment

2021 ◽  
Vol 18 ◽  
Author(s):  
Raja Murugesan ◽  
Sureshkumar Raman
Keyword(s):  
Prostate Cancer ◽  
Carbon Nanotubes ◽  
Drug Delivery ◽  
Drug Loading ◽  
High Surface ◽  
High Surface Area ◽  
High Capacity ◽  
Chemical Properties ◽  
Diagnosis And Treatment ◽  
High Level

: At present treatment methods for cancer are limited, partially due to the solubility, poor cellular distribution of drug molecules and, the incapability of drugs to annoy the cellular barriers. Carbon nanotubes (CNTs) generally have excellent physio-chemical properties, which include high-level penetration into the cell membrane, high surface area and high capacity of drug loading by in circulating modification with bio-molecules, project them as an appropriate candidate to diagnose and deliver drugs to prostate cancer (PCa). Additionally, the chemically modified CNTs which have excellent 'Biosensing' properties therefore makes it easy for detecting PCa without fluorescent agent and thus targets the particular site of PCa and also, Drug delivery can accomplish a high efficacy, enhanced permeability with less toxic effects. While CNTs have been mainly engaged in cancer treatment, a few studies are focussed on the diagnosis and treatment of PCa. Here, we detailly reviewed the current progress of the CNTs based diagnosis and targeted drug delivery system for managing and curing PCa.

Biological weathering in soil: the role of symbiotic root-associated fungi biosensing minerals and directing photosynthate-energy into grain-scale mineral weathering

2008 ◽  
Vol 72 (1) ◽  
pp. 85-89 ◽  
Author(s):  
J. R. Leake ◽  
A. L. Duran ◽  
K. E. Hardy ◽  
I. Johnson ◽  
D. J. Beerling ◽  
...  
Keyword(s):  
Carbon Allocation ◽  
High Surface ◽  
Turgor Pressure ◽  
High Surface Area ◽  
Volume Ratio ◽  
Mineral Weathering ◽  
Mycorrhizal Associations ◽  
P Content ◽  
Biological Weathering

AbstractBiological weathering is a function of biotic energy expenditure. Growth and metabolism of organisms generates acids and chelators, selectively absorbs nutrient ions, and applies turgor pressure and other physical forces which, in concert, chemically and physically alter minerals. In unsaturated soil environments, plant roots normally form symbiotic mycorrhizal associations with fungi. The plants provide photosynthate-carbohydrate-energy to the fungi in return for nutrients absorbed from the soil and released from minerals. In ectomycorrhiza, one of the two major types of mycorrhiza of trees, roots are sheathed in fungus, and 15—30% of the net photosynthate of the plants passes through these fungi into the soil and virtually all of the water and nutrients taken up by the plants are supplied through the fungi. Here we show that ectomycorrhizal fungi actively forage for minerals and act as biosensors that discriminate between different grain sizes (53—90 μm, 500—1000 μm) and different minerals (apatite, biotite, quartz) to favour grains with a high surface-area to volume ratio and minerals with the highest P content. Growth and carbon allocation of the fungi is preferentially directed to intensively interact with these selected minerals to maximize resource foraging.

scholarly journals Preparation and Characterization of Biocompatible Electrospun Nanofiber Scaffolds

2018 ◽  
Vol 62 (4) ◽  
Author(s):  
Edit Hirsch ◽  
Márió Nacsa ◽  
Ferenc Ender ◽  
Miklós Mohai ◽  
Zsombor K. Nagy ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Surface Characteristic ◽  
Poly Lactic Acid ◽  
Nanofibrous Scaffolds ◽  
Plasma Surface Treatment ◽  
Nanoscale Fibers ◽  
Solution Electrospinning

Nanoscale fibers were prepared for the fabrication of scaffolds by using a strong electrostatic field on the polymer solution. Electrospinning is widely applied for production of drug delivery, tissue engineering, and regenerative medicine systems as well as biosensors and enzyme immobilization. Nanofibers, thanks to their high surface area to volume ratio, can also mimic the extracellular matrix, thus it has been recognized as a suitable technique for the fast fabrication of scaffolds. This article demonstrates the fabrication of several nanofibrous scaffolds from biopolymers such as polycaprolactone, poly(lactic acid), poly(lactide-co-glycolide), poly(lactide-co-caprolactone) and poly(hydroxybutyrate-co-hydroxy valerate). The characterization and comparison of the scaffolds were achieved based on the morphology and surface characteristic of the nanofibers. The samples showed hydrophobic characteristic, thus a plasma surface treatment was applied successfully to increase hydrophilicity and the effect of the treatment was evaluated based on the wettability and the change in elemental composition of the surface based on X-ray photoelectron spectroscopy.

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