scholarly journals Prevention of Caries and Dental Erosion by Fluorides—A Critical Discussion Based on Physico-Chemical Data and Principles

2022 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Matthias Epple ◽  
Joachim Enax ◽  
Frederic Meyer
Keyword(s):  
Analytical Techniques ◽  
Dental Erosion ◽  
Critical Discussion ◽  
Point Of View ◽  
Tooth Surface ◽  
Minor Role ◽  
Literature Study ◽  
Physico Chemical ◽  
General Chemical ◽  
Tooth Surfaces

Dental erosion is a common problem in dentistry. It is defined as the loss of tooth mineral by the attack of acids that do not result from caries. From a physico-chemical point of view, the nature of the corroding acids only plays a minor role. A protective effect of fluorides, to prevent caries and dental erosion, is frequently claimed in the literature. The proposed modes of action of fluorides include, for example, the formation of an acid-resistant fluoride-rich surface layer and a fluoride-induced surface hardening of the tooth surface. We performed a comprehensive literature study on the available data on the interaction between fluoride and tooth surfaces (e.g., by toothpastes or mouthwashes). These data are discussed in the light of general chemical considerations on fluoride incorporation and the acid solubility of teeth. The analytical techniques available to address this question are presented and discussed with respect to their capabilities. In summary, the amount of fluoride that is incorporated into teeth is very low (a few µg mm−2), and is unlikely to protect a tooth against an attack by acids, be it from acidic agents (erosion) or from acid-producing cariogenic bacteria.

DMSP – Database for Modeling Signaling Pathways

2008 ◽  
Vol 47 (02) ◽  
pp. 104-148
Author(s):  
M. Breit ◽  
B. Pfeifer ◽  
C. Baumgartner ◽  
R. Modre-Osprian ◽  
B. Tilg ◽  
...  
Keyword(s):  
Knowledge Base ◽  
Signaling Pathways ◽  
Protein Interaction ◽  
Initial Step ◽  
Point Of View ◽  
Biological Knowledge ◽  
Literature Study ◽  
Online Databases ◽  
Qualitative Level ◽  
Pathway Models

Summary Objectives: Presently, the protein interaction information concerning different signaling pathways is available in a qualitative manner in different online protein interaction databases. The challenge here is to derive a quantitative way of modeling signaling pathways from qualitative way of modeling signaling pathways from a qualitative level. To address this issue we developed a database that includes mathematical modeling knowledge and biological knowledge about different signaling pathways. Methods: The database is part of an integrative environment that includes environments for pathway design, visualization, simulation and a knowledge base that combines biological and modeling information concerning pathways. The system is designed as a client-server architecture. It contains a pathway designing environment and a simulation environment as upper layers with a relational knowledge base as the underlying layer. Results: DMSP – Database for Modeling Signaling Pathways incorporates biological datasets from online databases like BIND, DIP, PIP, and SPiD. The modeling knowledge that has been incorporated is based on a literature study. Pathway models can be designed, visualized and simulated based on the knowledge stored in the DMSP. The user can download the whole dataset and build pathway models using the knowledge stored in our database. As an example, the TNF? pathway model was implemented and tested using this approach. Conclusion: DMSP is an initial step towards the aim of combining modeling and biological knowledge concerning signaling pathways. It helps in understanding pathways in a qualitative manner from a qualitative level. Simulation results enable the interpretation of a biological system from a quantitative and systemtheoretic point of view.

scholarly journals New EAF Slag Characterization Methodology for Strategic Metal Recovery

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1513
Author(s):  
Nour-Eddine Menad ◽  
Nassima Kana ◽  
Alain Seron ◽  
Ndue Kanari
Keyword(s):  
New Technologies ◽  
Slag Sample ◽  
Steel Slag ◽  
Analytical Techniques ◽  
Added Value ◽  
Metal Extraction ◽  
Magnetic Fraction ◽  
Magnetic Components ◽  
Physico Chemical ◽  
Hematite Fe2o3

The grown demand of current and future development of new technologies for high added value and strategic metals, such as molybdenum, vanadium, and chromium, and facing to the depletion of basic primary resources of these metals, the metal extraction and recovery from industrial by-products and wastes is a promising choice. Slag from the steelmaking sector contains a significant amount of metals; therefore, it must be considered to be an abundant secondary resource for several strategic materials, especially chromium. In this work, the generated slag from electric arc furnace (EAF) provided by the French steel industry was characterized by using multitude analytical techniques in order to determine the physico-chemical characteristics of the targeted slag. The revealed main crystallized phases are larnite (Ca2SiO4), magnetite (Fe3O4), srebrodolskite (Ca2Fe2O5), wüstite (FeO), maghemite (Fe2.6O3), hematite (Fe2O3), chromite [(Fe,Mg)Cr2O4], and quartz (SiO2). The collected slag sample contains about 34.1% iron (48.5% Fe2O3) and 3.5% chromium, whilst the vanadium contents is around 1500 ppm. The Mössbauer spectroscopy suggested that the non-magnetic fraction represents 42 wt% of the slag, while the remainder (58 wt%) is composed of magnetic components. The thermal treatment of steel slag up to 900 °C indicated that this solid is almost stable and few contained phases change their structures.

State of Research on Negative Pressure Techniques Applied to Leak Detection in Liquid Pipelines

2004 ◽  
Author(s):  
Wei Liang ◽  
Lai-bin Zhang ◽  
Zhao-hui Wang
Keyword(s):  
Pressure Wave ◽  
Analytical Techniques ◽  
Leak Detection ◽  
Point Of View ◽  
Detection Methods ◽  
Propagation Mechanism ◽  
Detection Techniques ◽  
Wave Detection ◽  
State Of Research ◽  
Signal Processing Methods

In China, the rarefaction-pressure wave techniques are widely used to diagnose the leakage fault for liquid pipelines. Many leaking propagating assumptions, such as stable single-phased flow hypothesis and none rarefaction wave front hypothesis, are often uncertain in the process of leak detection, which can easily result in some errors. Thus the rarefaction-pressure wave techniques should be integrated with other analytical techniques to compute a more accurate leak location. Additionally, the development trends of rarefaction-pressure wave techniques lie in three aspects. First, rarefaction-pressure wave detection techniques will be integrated with other compatible detection techniques and modern signal processing methods to solve the complex problems encountered in leak detection. Second, studies of rarefaction-pressure wave techniques have advanced to a new stage. The deductions on propagation mechanism of rarefaction-pressure wave have been successfully applied to determine leaks qualitatively. Third, analysis on rarefaction-pressure wave detection techniques will be made from a quantitative point of view. The quantitative data have been used to deduce leak amounts and location. The purpose of this paper is to present the recent achievements in the study of improved rarefaction-pressure wave detection techniques. The rarefaction-pressure wave detection methods, effects of incomplete information conditions, the improvements of rarefaction-pressure wave detection techniques with modified factors and propagation mechanisms are comprehensively investigated. The disfigurements of rarefaction-pressure wave are analyzed. The corresponding methods for resolving such problems as ill diagnostic information and weak amplitude values are put forward. Several methods for stronger small leakage detection ability, higher leakage positioning precision, lower false alarm rates are proposed. The application of rarefaction-pressure wave detection techniques to safety protection of liquid pipelines is also introduced. Finally, the prospect of rarefaction-pressure wave detection techniques is predicted.

Estimation of Gear Friction Coefficient using Directional Parameter of Tooth Surface

2021 ◽  
pp. 1-27
Author(s):  
Junichi Hongu ◽  
Ryohei Horita ◽  
Takao Koide
Keyword(s):  
Friction Coefficient ◽  
Contact Surface ◽  
Gear Tooth ◽  
Correction Term ◽  
Tooth Surface ◽  
Oil Film ◽  
Tooth Surfaces ◽  
Frictional Coefficients ◽  
Finishing Processes ◽  
The Relationship

Abstract This study proposes a modification of the Matsumoto equation using a directional parameter of tooth surfaces to adapt various gear finishing processes. The directional parameters of a contact surface, which affect oil film formations, have been discussed in the field of tribology; but this effect has been undetermined on the meshing gear tooth surfaces having directional machining marks. Thus, this paper investigates the relationship between the gear frictional coefficients and the directional parameters (based on ISO25178) of their tooth surfaces with the various finishing processes; and modifies the Matsumoto equation by introducing a new directional parameter to augment the various gear finishing processes. Our findings indicate that through optimizing the coefficient of the correction term the include the new directional parameter, the calculated friction values using the modified Matsumoto equation correlate more highly to the experimental friction values than that using the unmodified Matsumoto equation.

scholarly journals Perimolysis: case report

2015 ◽  
Vol 63 (2) ◽  
pp. 213-218
Author(s):  
Carolina Pratti DANIEL ◽  
Hérica Adad RICCI ◽  
Eloísa Marcantonio BOECK ◽  
Flavia Magnani BEVILACQUA ◽  
Jaqueline Braga Barbosa CERQUEIRA-LEITE
Keyword(s):  
Prescription Drugs ◽  
Resin Composite ◽  
Glass Ionomer Cement ◽  
Dental Erosion ◽  
Alcoholic Beverages ◽  
Dental Tissue ◽  
Restorative Treatment ◽  
Tooth Surfaces ◽  
Excessive Consumption ◽  
Ionomer Cement

Perimolysis is a form of dental erosion, characterized by dental tissue demineralization without bacterial involvement. It can be of intrinsic or extrinsic origin. Extrinsic origin is considered when it is caused by excessive consumption of acid drinks and foods such as soft drinks, alcoholic beverages, acid fruit and prescription drugs for daily use. When caused by gastrointestinal disorders, such as those resulting from bulimia, anorexia nervosa and gastroesophageal reflux, it is considered of intrinsic origin. The acid action can cause erosion on palatal/lingual incisor surfaces, and occlusal and palatal/lingual posterior tooth surfaces causing pain (dental hyperesthesia). Treatment is often multidisciplinary, and the causes should be identified, eliminated or controlled. In dentistry, the approach must include preventive measures to reduce future risks, and restorative intervention using materials such as glass ionomer cement, resin composite, or endodontic and prosthetic rehabilitation in more complex cases. The aim of this study was to describe the restorative treatment in the case of a patient with this condition.

scholarly journals A CRITICAL ANALYSIS OF THE COSMOLOGICAL IMPLEMENTATION OF LOOP QUANTUM GRAVITY

2012 ◽  
Vol 27 (07) ◽  
pp. 1250032 ◽  
Author(s):  
FRANCESCO CIANFRANI ◽  
GIOVANNI MONTANI
Keyword(s):  
Quantum Gravity ◽  
Quantum Cosmology ◽  
Loop Quantum Gravity ◽  
Critical Discussion ◽  
Point Of View ◽  
Graph Structure ◽  
Quantum Geometry ◽  
Cosmological Problem ◽  
New Perspective ◽  
Made In

This papers offers a critical discussion on the procedure by which Loop Quantum Cosmology (LQC) is constructed from the full Loop Quantum Gravity (LQG) theory. Revising recent issues in preserving SU(2) symmetry when quantizing the isotropic Universe, we trace a new perspective in approaching the cosmological problem within quantum geometry. The cosmological sector of LQG is reviewed and a critical point of view on LQC is presented. It is outlined how a polymer-like scale for quantum cosmology can be predicted from a proper fundamental graph underlying the homogeneous and isotropic continuous picture. However, such a minimum scale does not coincide with the choice made in LQC. Finally, the perspectives towards a consistent cosmological LQG model based on such a graph structure are discussed.

Kean Miltos: The Well-Known Iron Oxides of Antiquity

1997 ◽  
Vol 92 ◽  
pp. 359-371 ◽  
Author(s):  
E. Photos-Jones ◽  
A. Cottier ◽  
A. J. Hall ◽  
L. G. Mendoni
Keyword(s):  
Iron Oxides ◽  
Analytical Techniques ◽  
Field Work ◽  
Archaeological Record ◽  
The North ◽  
Naturally Occurring ◽  
Physico Chemical ◽  
Wide Range ◽  
Industrial Mineral

The island of Kea in the North Cyclades was well known in antiquity for its miltos, a naturally occurring red iron oxide valued for its colour and wide range of applications. By combining geological field work, physico-chemical analytical techniques, simulation (heating) experiments as well as simple laboratory tests, this paper describes the study of Kean iron oxides in an attempt to characterize this material which is still largely elusive in the archaeological record. The present work corroborates previous observations about the superior quality of some Kean iron oxides. Furthermore, it puts forward the hypothesis that miltos may have been considered an industrial mineral, and as such may have been used as an umbrella term for a variety of materials including mineralogically distinct purple as well as red iron oxides.

scholarly journals Exopolysaccharides Produced by Streptococcus mutans Glucosyltransferases Modulate the Establishment of Microcolonies within Multispecies Biofilms

2010 ◽  
Vol 192 (12) ◽  
pp. 3024-3032 ◽  
Author(s):  
H. Koo ◽  
J. Xiao ◽  
M. I. Klein ◽  
J. G. Jeon
Keyword(s):  
Streptococcus Mutans ◽  
Extracellular Polysaccharide ◽  
Fluorescence Labeling ◽  
Tooth Surface ◽  
Bacterial Cells ◽  
Actinomyces Naeslundii ◽  
Multispecies Biofilm ◽  
Tooth Surfaces ◽  
Glucan Synthesis

ABSTRACT Streptococcus mutans is a key contributor to the formation of the extracellular polysaccharide (EPS) matrix in dental biofilms. The exopolysaccharides, which are mostly glucans synthesized by streptococcal glucosyltransferases (Gtfs), provide binding sites that promote accumulation of microorganisms on the tooth surface and further establishment of pathogenic biofilms. This study explored (i) the role of S. mutans Gtfs in the development of the EPS matrix and microcolonies in biofilms, (ii) the influence of exopolysaccharides on formation of microcolonies, and (iii) establishment of S. mutans in a multispecies biofilm in vitro using a novel fluorescence labeling technique. Our data show that the ability of S. mutans strains defective in the gtfB gene or the gtfB and gtfC genes to form microcolonies on saliva-coated hydroxyapatite surfaces was markedly disrupted. However, deletion of both gtfB (associated with insoluble glucan synthesis) and gtfC (associated with insoluble and soluble glucan synthesis) is required for the maximum reduction in EPS matrix and biofilm formation. S. mutans grown with sucrose in the presence of Streptococcus oralis and Actinomyces naeslundii steadily formed exopolysaccharides, which allowed the initial clustering of bacterial cells and further development into highly structured microcolonies. Concomitantly, S. mutans became the major species in the mature biofilm. Neither the EPS matrix nor microcolonies were formed in the presence of glucose in the multispecies biofilm. Our data show that GtfB and GtfC are essential for establishment of the EPS matrix, but GtfB appears to be responsible for formation of microcolonies by S. mutans; these Gtf-mediated processes may enhance the competitiveness of S. mutans in the multispecies environment in biofilms on tooth surfaces.

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