scholarly journals Protection and Consolidation of Stone Heritage by Bacterial Carbonatogenesis

2021 ◽  
pp. 281-299
Author(s):  
Fadwa Jroundi ◽  
Maria Teresa Gonzalez-Muñoz ◽  
Carlos Rodriguez-Navarro
Keyword(s):  
Calcium Carbonate ◽  
Calcium Carbonate Precipitation ◽  
Weathering Processes ◽  
Novel Technology ◽  
Aesthetic Appearance ◽  
Stone Material ◽  
The Aesthetic ◽  
Taj Mahal ◽  
Future Work

AbstractFor millennia, artists and architects around the world used natural stone for the carving of sculptures and the construction of monuments, such as Roman, Greek, and Maya temples, the European cathedrals, and the Taj Mahal, just to name a few. Currently, the survival of these irreplaceable cultural and historical assets is under threat due to their continued degradation caused by various biotic and abiotic weathering processes that affect not only the aesthetic appearance of these structures, but also their durability and survival. The natural precipitation of calcium carbonate minerals by bacteria has been proposed for conservative interventions in monument restoration. This chapter reviews the application of biomineralization by (indigenous) bacterial carbonatogenesis as a novel technology for the protection and consolidation of altered ornamental materials. Carbonatogenesis is based on the ability of some bacteria to induce calcium carbonate precipitation. Laboratory and in situ results support the efficacy of bacterial carbonatogenesis, since remarkable protection and consolidation are achieved on the surface and in depth, without alterations in color or porosity, and without fostering the development of microbiota that could be harmful to the stone material. A discussion on the advantages of this novel biotechnology is provided. Challenges and future work on bioconsolidation of stone artifacts are also outlined.

scholarly journals Microbial-induced calcium carbonate precipitation: an experimental toolbox for in situ and real time investigation of micro-scale pH evolution

RSC Advances ◽  
2020 ◽  
Vol 10 (35) ◽  
pp. 20485-20493
Author(s):  
Jennifer Zehner ◽  
Anja Røyne ◽  
Alexander Wentzel ◽  
Pawel Sikorski
Keyword(s):  
Calcium Carbonate ◽  
Real Time ◽  
Experimental Methods ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Micro Scale ◽  
Ph Changes ◽  
Global And Local ◽  
Local Ph

We present two novel experimental methods to follow global and local pH changes on a microscale in bio-cementation processes.

scholarly journals Microbial-induced calcium carbonate precipitation: An experimental toolbox for in situ and real-time investigation of micro-scale pH evolution

2020 ◽  
Author(s):  
Jennifer Zehner ◽  
Anja Røyne ◽  
Alexander Wentzel ◽  
Pawel Sikorski
Keyword(s):  
Calcium Carbonate ◽  
Real Time ◽  
Small Sample ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Micro Scale ◽  
Ph Changes ◽  
Macro Scale ◽  
Local Ph

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

Bionic principles in the technology of robotic bioprinting of tooth enamel in situ

2017 ◽  
pp. 33-42
Author(s):  
И.Ю. Малышев ◽  
Г.С. Рунова ◽  
Ю.В. Подураев ◽  
М.А. Буйнов ◽  
Д.Д. Климов ◽  
...  
Keyword(s):  
Food Processing ◽  
Tooth Loss ◽  
Tooth Enamel ◽  
3D Bioprinting ◽  
Aesthetic Appearance ◽  
The Aesthetic ◽  
The Individual ◽  
Dental Prosthetics

Потеря зубов приводит к нарушению обработки пищи, ухудшает эстетический вид и в целом здоровье и качество жизни индивида. Главными причинами заболеваний и потери зубов являются повреждение эмали и кариес. Недостатки современных методов лечения повреждений эмали породили идею о выращивании биологических эквивалентов этой ткани. При этом стало очевидным, что восстановить полноценную эмаль можно только с учетом законов естественного развития этой ткани. В обзоре рассмотрены механизмы естественного амелогенеза, а затем на основе понимания этих механизмов проанализирована возможность разработки технологии восстановления эмали с помощью роботической 3D биопечати тканей in situ. Эти технологии могут обеспечить серьезные преимущества, например, увеличат до пожизненного срок годности «биопломбы»; решат проблему герметичности между новой и старой эмалью и снизят риски развития вторичного кариеса и других осложнений; снизят негативные последствия «человеческого фактора», и др. Есть основания полагать, что технологии роботической 3D биопечати in situ позволят восстанавливать не только отдельные ткани зуба, но и целый зуб и в значительной степени заменят существующие методы протезирования зубов. Loss of teeth leads to disruption of food processing, worsens the aesthetic appearance and generally, the health and quality of life of the individual. The major causes of diseases and tooth loss are damage to the enamel and caries. Limitations of current methods for treatment of enamel damage gave birth to the idea of growing biological equivalents of this tissue. At the same time, it became obvious that it is possible to regenerate the enamel only taking into account the laws of natural development of this tissue. The review focuses on mechanisms of natural amelogenesis, and then based on understanding of these mechanisms, analyzes a possibility of developing a technology for regeneration of enamel by means of in situ robotic 3D bioprinting of tissues. Such technologies might provide some serious benefits, for example, prolong the shelf life of dental biofillings to a lifetime; solve the problem of tightness between the new and old enamel and reduce the risk of developing secondary caries and other complications, etc. There is a reason to believe that the technology of in situ robotic 3D bioprinting will allow to restore not only tooth tissues, but also the whole tooth and largely replace the existing methods of dental prosthetics.

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

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