Investigations on the permeability of MgO concrete with 5-1-8 phase at the GV2-drift-sealing in the Teutschenthal mine

2020 ◽  
Author(s):  
Jennifer Arendt ◽  
Wolfram Kudla ◽  
Thomas Wilsnack ◽  
Till Popp ◽  
Daniela Freyer
Keyword(s):  
Large Scale ◽  
Gas Permeability ◽  
Pore Space ◽  
Binder Phase ◽  
Self Healing ◽  
Measuring Period ◽  
Mgo Concrete ◽  
Over Time ◽  
Drill Cores

<p>For underground storage facilities and future HAW repositories, a secure closure is indispensable. Within the scope of two consecutive research projects, three closure elements were installed in large-scale tests at the Teutschenthal mine in the Carnallitit Mountains between 2006 and 2008. Special mention should be made here of the large-scale test 2 (“GV2”), which was produced from MgO concrete with the 5-1-8 binder phase. This structure was made using the dry-mix shotcrete procedure. The low temperature development during the setting of the shotcrete was very advantageous. The 10.25 m long structure, with a height and width of 3.55 m each, consists of 104 concreting sections with an average layer thickness of 9.9 cm. It was of interest whether the concreting section boundaries (“BAG”) influence the permeability (negatively). The structure is equipped with pressure transmitters and TDR sensors in three measuring levels. After completion of the structure and injections in the contact area, the integral system permeability was 2*10<sup>‑16</sup> m². Liquid pressurization via pressure chamber was carried out on the test structure after a maturing period of about 10 years. After 8 years, the permeability with gas and with solution was determined in boreholes and on drill cores, especially with regard to the development over time. The determined in-situ gas permeability is on average 2.7*10<sup>‑19</sup> m², on compact concrete (without BAGs) on average 2.0*10<sup>-20</sup> m². Test areas containing BAGs showed a higher permeability of maximum three orders of magnitude in some measurements. The solution permeability was determined both with a saturated NaCl solution and with a NaCl-saturated solution containing MgCl<sub>2</sub> and is between 1.0*10<sup>‑20</sup> m² and 9.0*10<sup>‑20</sup> m², whereby this decreases by half a power of ten over the measurement period of 600 days. In further integral injection tests in 4.5 m and 4.8 m long boreholes, a significant decrease in permeability over time was also observed. From an initial 2*10<sup>‑15</sup> m² and 4*10<sup>‑16</sup> m², respectively, the integral permeability decreased to <10<sup>‑19</sup> m² over a measuring period of 2.5 years. The reason for this decrease is the reduction of pore space due to the recrystallization of MgO and the transformation of the metastable 5-1-8 phase to the long-term stable 3-1-8 phase due to the increase in volume that takes place when the solution is added. Potential weak points or defects at the technically determined concrete section boundaries, therefore, do not represent weak zones in the structure in the long term due to this self-healing effect.</p><p>This paper reports on the large-scale experiment GV2 made of MgO concrete with 5-1-8 phase and the comprehensive permeability and strength investigations in drillings and on drill cores. The test results are the precondition for a modeling of the long-term behaviour of MgO-concrete.</p>

scholarly journals Chromosomal Rearrangements in Salmonella enterica Serovar Typhi Strains Isolated from Asymptomatic Human Carriers

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
T. David Matthews ◽  
Wolfgang Rabsch ◽  
Stanley Maloy
Keyword(s):  
Salmonella Enterica ◽  
Large Scale ◽  
Chromosomal Rearrangements ◽  
Growth Conditions ◽  
Genetic Changes ◽  
Content Type ◽  
Long Term Storage ◽  
Bacterial Chromosomes ◽  
Over Time

ABSTRACTHost-specific serovars ofSalmonella entericaoften have large-scale chromosomal rearrangements that occur by recombination betweenrrnoperons. Two hypotheses have been proposed to explain these rearrangements: (i) replichore imbalance from horizontal gene transfer drives the rearrangements to restore balance, or (ii) the rearrangements are a consequence of the host-specific lifestyle. Although recent evidence has refuted the replichore balance hypothesis, there has been no direct evidence for the lifestyle hypothesis. To test this hypothesis, we determined therrnarrangement type for 20Salmonella entericaserovar Typhi strains obtained from human carriers at periodic intervals over multiple years. These strains were also phage typed and analyzed for rearrangements that occurred over long-term storage versus routine culturing. Strains isolated from the same carrier at different time points often exhibited different arrangement types. Furthermore, colonies isolated directly from the Dorset egg slants used to store the strains also had different arrangement types. In contrast, colonies that were repeatedly cultured always had the same arrangement type. Estimated replichore balance of isolated strains did not improve over time, and some of the rearrangements resulted in decreased replicore balance. Our results support the hypothesis that the restricted lifestyle of host-specificSalmonellais responsible for the frequent chromosomal rearrangements in these serovars.IMPORTANCEAlthough it was previously thought that bacterial chromosomes were stable, comparative genomics has demonstrated that bacterial chromosomes are dynamic, undergoing rearrangements that change the order and expression of genes. While mostSalmonellastrains have a conserved chromosomal arrangement type, rearrangements are very common in host-specificSalmonellastrains. This study suggests that chromosome rearrangements in the host-specificSalmonella entericaserovar Typhi, the causal agent of typhoid fever, occur within the human host over time. The results also indicate that rearrangements can occur during long-term maintenance on laboratory medium. Although these genetic changes do not limit survival under slow-growth conditions, they may limit the survival ofSalmonellaTyphi in other environments, as predicted for the role of pseudogenes and genome reduction in niche-restricted bacteria.

scholarly journals Maturing global CO2 storage resources on offshore continental margins to achieve 2DS emissions reductions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
P. S. Ringrose ◽  
T. A. Meckel
Keyword(s):  
Large Scale ◽  
Storage Capacity ◽  
Pore Space ◽  
Co2 Storage ◽  
Emissions Reduction ◽  
Continental Margins ◽  
Emissions Reductions ◽  
Injection Wells ◽  
Reduction Strategies

AbstractMost studies on CO2 emissions reduction strategies that address the ‘two-degree scenario’ (2DS) recognize a significant role for CCS. For CCS to be effective, it must be deployed globally on both existing and emerging energy systems. For nations with large-scale emissions, offshore geologic CO2 storage provides an attractive and efficient long-term strategy. While some nations are already developing CCS projects using offshore CO2 storage resources, most geographic regions have yet to begin. This paper demonstrates the geologic significance of global continental margins for providing broadly-equitable, geographically-relevant, and high-quality CO2 storage resources. We then use principles of pore-space utilization and subsurface pressure constraints together with analogs of historic industry well deployment rates to demonstrate how the required storage capacity can be developed as a function of time and technical maturity to enable the global deployment of offshore storage for facilitating 2DS. Our analysis indicates that 10–14 thousand CO2 injection wells will be needed globally by 2050 to achieve this goal.

scholarly journals O7C.2 Developing a measuring strategy for monitoring and evaluation of a national occupational health intervention programme in great britain (GB)

2019 ◽  
Vol 76 (Suppl 1) ◽  
pp. A64.3-A65
Author(s):  
Yiqun Chen ◽  
Andrew Curran
Keyword(s):  
Occupational Health ◽  
Large Scale ◽  
National Level ◽  
Health And Safety ◽  
Monitoring And Evaluation ◽  
Work Related ◽  
Measurement Framework ◽  
Wide Range ◽  
Over Time

The Health and Safety Executive (HSE) is the GB regulator for health and safety at work. The HSE Health and Work (H&W) program designs and carries out a wide range of interventions; including inspection, enforcement and other regulatory activities as well as prevention; targeting priority health conditions in high-risk sectors. It is anticipated that long-term, sustainable and coordinated actions developed as part of the program will over time improve awareness, behaviors, control of exposures, and, as a result, prevent work-related ill health in GB workforce.An HSE Measuring Strategy, together with measurement framework and principles, has been developed. The measurement framework draws together data systems, covering Attitudes (A), Behaviors (B), Control of exposures (C), and Disease and work-related ill health reduction (D), based on a simple model to provide evidence required for evaluating the short, medium and long term impacts of the large scale and complex H&W program on the GB health and safety system. The Strategy gives a new focus on measuring behavioral changes and risk reductions; and emphasizes longitudinal measurement designs to assess progress over time.For developing the Strategy, workshops were organized to bring stakeholders across HSE to review existing systems for conducting population surveys, collecting exposure intelligence and occupational health surveillance, which have contributed to forming a long-term vision of fit-for-purpose measurement systems.We will present the development of the Strategy and the plans to implement it with the H&W program, which requires close collaborations between epidemiologists and social researchers, policy makers, and other multidisciplinary regulatory specialists. The lessons learnt will help HSE towards building the right evidence base for monitoring and evaluation of a range of national level intervention programs for work-related ill health prevention.©British Crown copyright (2019)

Women in Construction and the Workforce Investment Act

2016 ◽  
Vol 41 (4) ◽  
pp. 333-354 ◽  
Author(s):  
Carolyn Arcand
Keyword(s):  
Metropolitan Area ◽  
Large Scale ◽  
Construction Project ◽  
Scale Construction ◽  
Workforce Investment Act ◽  
Hours Worked ◽  
Career Opportunities ◽  
General Decline ◽  
Over Time

This article examines whether women’s representation among senior-level construction jobs increased over time during a long-term, large-scale construction project in Boston, Massachusetts, and whether enactment of the Workforce Investment Act (WIA) has fostered support and connection to construction career opportunities for women in this metropolitan area. Results show that the proportion of hours worked by women in senior-level positions on the project was relatively high for a few years, followed by a general decline across all job types, and the WIA did not significantly enhance opportunities for women in construction.

scholarly journals Shallow firn cores 1989–2019 in southwest Greenland's percolation zone reveal decreasing density and ice layer thickness after 2012

2021 ◽  
pp. 1-12
Author(s):  
Åsa K. Rennermalm ◽  
Regine Hock ◽  
Federico Covi ◽  
Jing Xiao ◽  
Giovanni Corti ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Pore Space ◽  
Greenland Ice Sheet ◽  
Infiltration Capacity ◽  
In Situ Observations ◽  
Percolation Zone ◽  
Over Time ◽  
Southwest Greenland

Abstract Refreezing of meltwater in firn is a major component of Greenland ice-sheet's mass budget, but in situ observations are rare. Here, we compare the firn density and total ice layer thickness in the upper 15 m of 19 new and 27 previously published firn cores drilled at 15 locations in southwest Greenland (1850–2360 m a.s.l.) between 1989 and 2019. At all sites, ice layer thickness covaries with density over time and space. At the two sites with the earliest observations (1989 and 1998), bulk density increased by 15–18%, in the top 15 m over 28 and 21 years, respectively. However, following the extreme melt in 2012, elevation-detrended density using 30 cores from all sites decreased by 15 kg m−3 a−1 in the top 3.75 m between 2013 and 2019. In contrast, the lowest elevation site's density shows no trend. Thus, temporary build-up in firn pore space and meltwater infiltration capacity is possible despite the long-term increase in Greenland ice-sheet melting.

Large-scale tests to investigate MgO concrete with a long-term stable 3-1-8 phase in the Sondershausen and Teutschenthal mines

2020 ◽  
Author(s):  
Jan Aurich ◽  
Daniela Freyer ◽  
Matthias Gruner ◽  
Wolfram Kudla
Keyword(s):  
Large Scale ◽  
Salt Mine ◽  
Binding Reaction ◽  
Scale Experiment ◽  
One Year ◽  
Mgo Concrete ◽  
Large Scale Tests ◽  
Sealing Elements ◽  
Vertical Borehole

<p>These abstract bases on the R & D project ELSA Phase II - Concept development for shaft seals and testing of sealing elements for HAW repositories, funded by the German Federal Ministry of Energy and Economic Affairs.</p><p>The installation of sealing elements in salt rock requires a mechanical support system, which is chemical compatible with the host rock. In future HAW-repositories abutments and sealing elements within the shafts and drifts could be made of magnesia building material with the long term stable 3-1-8 binder phase, if solution containing magnesium can attack the seal.</p><p>In 2014 a first large-scale experiment was performed in the Sondershausen salt mine in Germany. A vertical borehole with the depth of two meters and a diameter of 1.1 meter was filled with the magnesia-based concrete. Several sensors measured the development of temperature, comprehensive stress and expansion within the test construction for approximately one year. During the binding reaction the temperature increased by 55 K in the center. After 150 days, the expansion in axial direction reached 2.4 mm/m and 1.1 mm/m in radial direction.</p><p>In 2018 a second large-scale-experiment was performed in the Teutschenthal salt mine, Germany to continue the investigations. A new vertical borehole with the depth of 3.5 meters and a diameter of 1.3 meters was filled with the same material. The temperature in the center increased by 40 K during the binding reaction and decreased down to the ambient temperature after 20 days. In result of the first experiences, the stress sensor range was increased. After one year a comprehensive stress of 6.2 MPa was measured at the contour and is still evolving at this point (early 2020). The maximum axial expansion reached 7.9 mm/m and stays at this level. The maximum radial expansion reached 0.7 mm/m 20 days after concreting and decreased subsequently. This material behavior corresponds to the high comprehensive stress level.</p><p>The second experiment is equipped with a pressure chamber at the bottom. A first determination of the integral gas permeability revealed a value of approx. 3E<sup>-18 </sup>m² to 3E<sup>-17 </sup>m². In the near term a multistage pressurization of the construction is planned, using a saturated NaCl solution to evaluate the sealing ability.</p><p>This contribution reports on the measured parameters (temperature, stress, strain) of the two large-scale tests with long-term stable MgO-concrete and the composition requirements to obtain a long-term stable MgO concrete. Long-term stable MgO concrete with 3-1-8 phase has been used for the first time in these tests. The measured test-results are the foundation for modelling the behaviour of the MgO-concrete.</p>

Terminology of long-term geomorphology: a Scandinavian perspective

2009 ◽  
Vol 33 (2) ◽  
pp. 163-182 ◽  
Author(s):  
Karin Ebert
Keyword(s):  
Sea Level ◽  
Land Surface ◽  
Large Scale ◽  
Ice Sheets ◽  
Stepped Surfaces ◽  
Base Level ◽  
History Of ◽  
Land Surfaces ◽  
Over Time

In this paper the terminology used in long-term geomorphology is evaluated. Long-term geomorphology is the study of landforms that are of mostly pre-Quaternary, Cenozoic, Mesozoic or even Palaeozoic age. Many terms have been introduced to name the long-term large-scale landforms that persist to the present. The definitions of many of these terms are ambiguous, have changed over time, and their use and meaning is consequently often unclear. An attempt is made to clarify definitions, when possible, and to facilitate more concise usage of these terms. Long-term geomorphology deals in great parts with the lowering of a land surface to the base level (mostly sea level), leaving a new land surface. The largest group of terms concerns descriptions and genetic models for these kinds of new land surfaces collectively called `base level surfaces' here. Other terms discussed here relate to relict and preglacial landforms and regional terms for stepped surfaces. Terminology is discussed with particular reference to examples from and its use in Scandinavia. There is a long history of long-term geomorphology study in this region. Scandinavia is unique in the respect that pre-Quaternary landforms were repeatedly covered by Quaternary ice sheets but often survived with different degrees of glacial modification.

scholarly journals Understanding usage style transformation during long-term smartwatch use

2021 ◽  
Author(s):  
Aku Visuri ◽  
Niels van Berkel ◽  
Jorge Goncalves ◽  
Reza Rawassizadeh ◽  
Denzil Ferreira ◽  
...  
Keyword(s):  
Large Scale ◽  
Previous Literature ◽  
Shared Understanding ◽  
Market Growth ◽  
Early Adoption ◽  
The Individual ◽  
Over Time ◽  
Usage Data

AbstractDespite large investments in smartwatch development, the market growth remains smaller than forecasted. The purpose of smartwatch use remains unclear, indicated by the lack of large-scale adoption. Thus, we aim to better understand the early adoption and everyday smartwatch use. We investigate a diverse usage data of smartwatches logged over a period of up to 14 months from 79 individuals between December 2015 and March 2017, one of the largest wearable datasets collected. First, we identify both explorative and accepted behaviours that users exhibit and further investigate how the individual usage traits and features differ between the two categories. Our analysis offers an insightful perspective on how smartwatch use evolves organically. Our results improve our shared understanding of smartwatch use and users adapting their use of smartwatch over time to match the capabilities of the technology by validating numerous findings from previous literature.

Large-scale fabrication of durable and self-healing super-hydrophobic coating with high thermal stability and long-term corrosion resistance

Nanoscale ◽  
2021 ◽  
Author(s):  
Dawei Li ◽  
Liangji Ma ◽  
Bo Zhang ◽  
Chen Shaohua
Keyword(s):  
Thermal Stability ◽  
Large Scale ◽  
High Thermal Stability ◽  
Self Healing ◽  
Superhydrophobic Coating ◽  
Hydrophobic Coating ◽  
Superhydrophobic Coatings ◽  
Crucial Feature ◽  
Cheap Method

Durability is a crucial feature to expand the application field of artificial superhydrophobic coatings. Herein, a kind of durable superhydrophobic coating is prepared by a simple and cheap method using...

scholarly journals Minimizing Oxidation of Freeze-Dried Monoclonal Antibodies in Polymeric Vials Using a Smart Packaging Approach

Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1695
Author(s):  
Nicole Härdter ◽  
Tim Menzen ◽  
Gerhard Winter
Keyword(s):  
Monoclonal Antibodies ◽  
Gas Permeability ◽  
Drug Product ◽  
Mechanical Shock ◽  
Smart Packaging ◽  
Term Stability ◽  
Long Term Stability ◽  
Freeze Dried ◽  
Over Time

Primary containers made of cyclic olefin polymer (COP) have recently gained attention since they may overcome several risks and shortcomings of glass containers as they exhibit a high break resistance, biocompatibility, and homogeneous heat transfer during lyophilization. On the downside, COP is more permeable for gases, which can lead to an ingress of oxygen into the container over time. Since oxidation is an important degradation pathway for monoclonal antibodies (mAbs), the continuous migration of oxygen into drug product containers should be avoided overall. To date, no long-term stability studies regarding lyophilizates in polymer vials have been published, potentially because of the unbearable gas permeability. In this study, we demonstrate that after lyophilization in COP vials and storage of these vials in aluminum pouches together with combined oxygen and moisture absorbers (“smart packaging”), oxidation of two lyophilized therapeutic antibodies was as low as in glass vials due to the deoxygenated environment in the pouch. Nevertheless, active removal of oxygen from the primary container below the initial level over time during storage in such “smart” secondary packaging was not achieved. Furthermore, residual moisture was controlled. Overall, the smart packaging reveals a promising approach for long-term stability of biopharmaceuticals; in addition to COP’s known benefits, stable, low oxygen and moisture levels as well as the protection from light and cushioning against mechanical shock by the secondary packaging preserve the sensitive products very well.

Sign in / Sign up

Export Citation Format

Share Document