scholarly journals Potential of Advanced Consolidants for the Application on Sandstone Rocks: A Comparative Study

2019 ◽  
Author(s):  
Monika Remzova ◽  
Radek Zouzelka ◽  
Jaroslav Lukes ◽  
Jiri Rathousky
Keyword(s):  
Mechanical Strength ◽  
Mechanical Performance ◽  
Accelerated Weathering ◽  
Long Term Stability ◽  
Before And After ◽  
Application Potential ◽  
Degree Of Consolidation ◽  
Drilling Resistance

To achieve efficient and durable consolidation of weathered sandstone, the selection of a suitable consolidant is essential. To reasonably assess the suitability of different formulations, it is fundamental to compare their performance as a consolidant within a substrate, which reliably models the properties of deteriorated material. As a test substrate, the sandstone from quarries in Mšené in central Bohemia was selected, for its developed porosity and relatively low mechanical strength. To obtain relevant comparison of their application potential, both commercial (Remmers KSE OH and Surfapore) and self-developed consolidants were included. To test the long-term stability of each consolidant, the stone was subjected to accelerated weathering. The characterization of texture properties was based on the physical sorption of nitrogen and krypton, mercury intrusion porosimetry and water uptake. While the mechanical properties in microscale were determined by nanoindentation, the mechanical strength in macroscale before and after consolidation was measured by drilling resistance. Both commercial exhibited good mechanical performance with reasonable durability. The performance of our developed samples was comparable or, in some cases, superior. Very interesting were the consolidants containing TiO2 and ZnO nanoparticles, the former exhibiting comparable degree of consolidation and durability as commercial ones, with additional photocatalytic function, the latter unusually high increase in the mechanical strength, even after the weathering test. The diammonium hydrogen phosphate based consolidant showed exceptional durability in the weathering test, which makes it a promising product not only for carbonate but also sandstone materials.

Enhanced stability of conductive polyacetylene in ladder-like surface-grafted brushes

2016 ◽  
Vol 7 (36) ◽  
pp. 5664-5670 ◽  
Author(s):  
Michał Szuwarzyński ◽  
Karol Wolski ◽  
Szczepan Zapotoczny
Keyword(s):  
Term Stability ◽  
Long Term Stability ◽  
Enhanced Stability

Formation and characterization of polyacetylene-based brushes that exhibit exceptional long term stability in air is presented here.

scholarly journals Biochemical Characterization of Phenylacetaldehyde Dehydrogenases from Styrene-degrading Soil Bacteria

2020 ◽  
Author(s):  
Juliane Zimmerling ◽  
Michel Oelschlägel ◽  
Carolin Großmann ◽  
Matthias Voitel ◽  
Michael Schlömann ◽  
...  
Keyword(s):  
Esterase Activity ◽  
Soil Bacteria ◽  
Biochemical Characterization ◽  
Specific Activity ◽  
Aldehyde Dehydrogenases ◽  
Long Term Stability ◽  
Almost All ◽  
Different Characteristics

Abstract Four phenylacetaldehyde dehydrogenases (designated as FeaB or StyD) originating from styrene-degrading soil bacteria were biochemically investigated. In this study, we focused on the Michaelis-Menten kinetics towards the presumed native substrate phenylacetaldehyde and the obviously preferred co-substrate NAD+. Furthermore, the substrate specificity on four substituted phenylacetaldehydes and the co-substrate preference were studied. Moreover, these enzymes were characterized with respect to their temperature as well as long-term stability. Since aldehyde dehydrogenases are known to show often dehydrogenase as well as esterase activity, we tested this capacity, too. Almost all results showed clearly different characteristics between the FeaB and StyD enzymes. Furthermore, FeaB from Sphingopyxis fribergensis Kp5.2 turned out to be the most active enzyme with an apparent specific activity of 17.8 ± 2.1 U mg-1. Compared with that, both StyDs showed only activities less than 0.2 U mg-1 except the overwhelming esterase activity of StyD-CWB2 (1.4 ± 0.1 U mg-1). The clustering of both FeaB and StyD enzymes with respect to their characteristics could also be mirrored in the phylogenetic analysis of twelve dehydrogenases originating from different soil bacteria.

Properties of a-Si:H and a-SiGe:H Films Deposited by Photo-Assisted CVD

1986 ◽  
Vol 70 ◽  
Author(s):  
R. E. Rocheleau ◽  
S. C. Jackson. ◽  
S. S. Hegedus ◽  
B. N. Baron
Keyword(s):  
High Efficiency ◽  
Chemical Vapor ◽  
Photovoltaic Cell ◽  
Gas Flows ◽  
Long Term Stability ◽  
Improved Stability ◽  
Deposition Processes ◽  
P Type

ABSTRACTChemical vapor deposition techniques, in particular plasma enhanced CVD, have been used to produce high quality a-Si:H materials. Continuing research is directed toward increased device performance, improved stability, and translation of scale to commercial production. A part of this effort is the evaluation of alternate CVD techniques which in addition to providing technical options for high efficiency and long term stability are likely to lead to improved understanding of the relationships between deposition processes and material properties. A relatively new technique for depositing a-Si:H is photo-CVD which utilizes ultraviolet light to initiate the decomposition of silane or disilane. The best results from both materials properties and device efficiency points of view have been achieved using mercury sensitized photo-CVD. Recently, a 10.5% efficient a-Si:H p-i-n photovoltaic cell, fabricated by photo-CVD, was reported [1]. A limitation in photo-CVD has been preventing deposition on the UV transparent window. In this paper we describe a new photo-CVD reactor with a moveable UV-transparent Teflon film and secondary gas flows to eliminate window fouling. The deposition and opto-electronic characterization of intrinsic a-Si:H and a-SiGe:H and p-type a-SiC:H are described. Finally, preliminary results of p-i-n solar cells are presented.

scholarly journals Predicting the long-term stability of compact multiplanet systems

2020 ◽  
Vol 117 (31) ◽  
pp. 18194-18205 ◽  
Author(s):  
Daniel Tamayo ◽  
Miles Cranmer ◽  
Samuel Hadden ◽  
Hanno Rein ◽  
Peter Battaglia ◽  
...  
Keyword(s):  
Machine Learning Techniques ◽  
Training Dataset ◽  
Complementary Method ◽  
Long Term Stability ◽  
Learning Techniques ◽  
Resonant Dynamics ◽  
The Stability ◽  
Long Timescales

We combine analytical understanding of resonant dynamics in two-planet systems with machine-learning techniques to train a model capable of robustly classifying stability in compact multiplanet systems over long timescales of109orbits. Our Stability of Planetary Orbital Configurations Klassifier (SPOCK) predicts stability using physically motivated summary statistics measured in integrations of the first104orbits, thus achieving speed-ups of up to105over full simulations. This computationally opens up the stability-constrained characterization of multiplanet systems. Our model, trained on ∼100,000 three-planet systems sampled at discrete resonances, generalizes both to a sample spanning a continuous period-ratio range, as well as to a large five-planet sample with qualitatively different configurations to our training dataset. Our approach significantly outperforms previous methods based on systems’ angular momentum deficit, chaos indicators, and parametrized fits to numerical integrations. We use SPOCK to constrain the free eccentricities between the inner and outer pairs of planets in the Kepler-431 system of three approximately Earth-sized planets to both be below 0.05. Our stability analysis provides significantly stronger eccentricity constraints than currently achievable through either radial velocity or transit-duration measurements for small planets and within a factor of a few of systems that exhibit transit-timing variations (TTVs). Given that current exoplanet-detection strategies now rarely allow for strong TTV constraints [S. Hadden, T. Barclay, M. J. Payne, M. J. Holman,Astrophys. J.158, 146 (2019)], SPOCK enables a powerful complementary method for precisely characterizing compact multiplanet systems. We publicly release SPOCK for community use.

Sign in / Sign up

Export Citation Format

Share Document