Micro-scale Real-Time Wear Dynamics Investigated by Synchroton Radiation

AbstractConcrete is the second most consumed product by humans, after water. However, the production of cement, which is used as a binding material in concrete, causes more than 5% of anthropogenic CO2 emissions and has therefore a significant contribution to climate change and global warming. Due to increasing environmental awareness and international climate goals, there is a need for emission-reduced materials, that can replace conventional concrete in certain applications. One path to produce a solid, concrete-like construction material is microbial-induced calcium carbonate precipitation (MICP). As a calcium source in MICP, crushed limestone, which mainly consists out of CaCO3, can be dissolved with acids, for example lactic acid. The pH evolution during crystallization and dissolution processes provides important information about kinetics of the reactions. However, previous research on MICP has mainly been focused on macro-scale pH evolution and on characterization of the finished material. To get a better understanding of MICP it is important to be able to follow also local pH changes in a sample. In this work we present a new method to study processes of MICP at micro-scale in situ and in real time. We present two different methods to monitor the pH changes during the precipitation process of CaCO3. In the first method, the average pHs of small sample volumes are measured in real time, and pH changes are subsequently correlated with processes in the sample by comparing to optical microscope results. The second method is introduced to follow local pH changes at a grain scale in situ and in real time. Furthermore, local pH changes during the dissolution of CaCO3 crystals are monitored. We demonstrate that these two methods are powerful tools to investigate pH changes for both MICP precipitation and CaCO3 dissolution for knowledge-based improvement of MICP-based material properties.Graphical TOC Entry

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Exploiting micro-scale structural and chemical observations in real time for understanding chemical conversion: LEEM/PEEM studies over CeOx–Cu(111)

Ultramicroscopy ◽

10.1016/j.ultramic.2017.05.003 ◽

2017 ◽

Vol 183 ◽

pp. 84-88 ◽

Cited By ~ 2

Author(s):

Tomáš Duchoň ◽

Johanna Hackl ◽

Jan Höcker ◽

Kateřina Veltruská ◽

Vladimír Matolín ◽

...

Keyword(s):

Real Time ◽

Chemical Conversion ◽

Micro Scale

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Recording holograms of micro-scale objects in real time

Laser Physics ◽

10.1088/1054-660x/23/3/036002 ◽

2013 ◽

Vol 23 (3) ◽

pp. 036002 ◽

Cited By ~ 2

Author(s):

A Chirita ◽

N Kukhtarev ◽

O Korshak ◽

V Prilepov ◽

Iu Jidcov

Keyword(s):

Real Time ◽

Micro Scale

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Some Recent Results in Quiescent Prominence Spectrometry

International Astronomical Union Colloquium ◽

10.1017/s0252921100065179 ◽

1979 ◽

Vol 44 ◽

pp. 41-47

Author(s):

Donald A. Landman

Keyword(s):

Real Time ◽

Computer System ◽

Spectral Response ◽

Absolute Intensity ◽

Solar Observatory ◽

Target Size ◽

Small Target ◽

Signal Averaging ◽

Quiescent Prominence

This paper describes some recent results of our quiescent prominence spectrometry program at the Mees Solar Observatory on Haleakala. The observations were made with the 25 cm coronagraph/coudé spectrograph system using a silicon vidicon detector. This detector consists of 500 contiguous channels covering approximately 6 or 80 Å, depending on the grating used. The instrument is interfaced to the Observatory’s PDP 11/45 computer system, and has the important advantages of wide spectral response, linearity and signal-averaging with real-time display. Its principal drawback is the relatively small target size. For the present work, the aperture was about 3″ × 5″. Absolute intensity calibrations were made by measuring quiet regions near sun center.

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Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010216x ◽

1988 ◽

Vol 46 ◽

pp. 16-17

Author(s):

Alan S. Rudolph ◽

Ronald R. Price

Keyword(s):

Real Time ◽

Self Assembly ◽

Freeze Drying ◽

Video Capture ◽

Drying Process ◽

Artificial Membranes ◽

The Past ◽

Cryo Electron Microscopy ◽

Spherical Structures ◽

Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

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An Interactive Minicomputer Program for the Indexing and Simulation of Electron Diffraction Patterns

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092670 ◽

1976 ◽

Vol 34 ◽

pp. 542-543

Author(s):

R.P. Goehner ◽

W.T. Hatfield ◽

Prakash Rao

Keyword(s):

Electron Diffraction ◽

Real Time ◽

Pattern Analysis ◽

Flow Diagram ◽

Hard Copy ◽

Time Analysis ◽

Real Time Analysis ◽

Transmission Electron ◽

One Step ◽

Diffraction Patterns

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.

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