The effect of cigarette smoking on the virulence of streptococcus mutans caries and cardiovascular diseases-epidemiological analysis and in vitro studies

Indiana University-Purdue University Indianapolis (IUPUI)The impact of tobacco smoking on human health is well documented. The influence of smoking on tooth loss and cardiovascular diseases was investigated in the current study via both epidemiology and in vitro studies. From analyzing the 2006 Behavioral Risk Factor Surveillance System (2006 BRFSS) database, we confirmed that smoking was significantly associated with the number of teeth lost in a dose-dependent manner and smoking cessation reduced the risk when compared to those subjects continuing to smoke. In addition, the virulence factors related to caries were compared between Streptococcus mutans and Streptococcus gordonii in response to cigarette smoking condensate (CSC) treatment. We observed that S. gordonii was more susceptible to CSC treatment than S. mutans. CSC significantly enhanced S. mutans sucrose-dependent and independent adherence. Western blot assays revealed that several bacterial surface proteins including glucosyltransferase (GTF), glucan-binding proteins and antigen I/II, were significantly upregulated for the treated S. mutans. These findings suggested that the oral environment with CSC may favor a cariogenic dominant composition, which may increase the risk for smokers to develop caries. We also found that smoking and oral health status modified each other and synergistically increased the risk of CVD and this joint effect was more pronounced among the youngest age group using the 2006 BRFSS database. To further understand the joint effect, we conducted an in vitro study to investigate bacterial attachment to fibronectin and endothelial cells in response to smoking condensate treatment. Our study clearly demonstrated CSC significantly enhanced S. mutans attachment to both soluble and immobilized fibronectin as well as endothelial cells. Furthermore, our data suggested that bacteria possessed several adhesins that bound to host tissues and endothelial cells also had multiple receptors for bacterial attachment. Among these adhesins, antigen I/II seemed essential for bacterial attachment to endothelial cells without CSC. The knowledge of bacterial attachment to host tissues in the presence of CSC may help in developing different preventive or therapeutic strategies against attachment and colonization of the host by S. mutans

Cleaning graphene : a first quantum/classical molecular dynamics approach

Graphene outstanding properties created a huge interest in the condensed matter community and unprecedented fundings at the international scale in the hope of application developments. Recently, there have been several reports of incomplete removal of the polymer resists used to transfer as-grown graphene from one substrate to another, resulting in altered graphene transport properties. Finding a large-scale solution to clean graphene from adsorbed residues is highly desirable and one promising possibility would be to use hydrogen plasmas. In this spirit, we couple here quantum and classical molecular dynamics simulations to explore the kinetic energy ranges required by atomic hydrogen to selectively etch a simple residue, a CH3 group, without irreversibly damaging the graphene. For incident energies in the 2-15 eV range, the CH3 radical can be etched by forming a volatile CH4 compound which leaves the surface, either in the CH4 form or breaking into CH3+H fragments, without further defect formation. At this energy, adsorption of H atoms on graphene is possible and further annealing will be required to recover pristine graphene.Comment: 9 figures, 27 page

Black Silicon with high density and high aspect ratio nanowhiskers

Physical properties of black Silicon (b-Si) formed on Si wafers by reactive ion etching in chlorine plasma are reported in an attempt to clarify the formation mechanism and the origin of the observed optical and electrical phenomena which are promising for a variety of applications. The b-Si consisting of high density and high aspect ratio sub-micron length whiskers or pillars with tip diameters of well under 3 nm exhibits strong photoluminescence (PL) both in visible and infrared, which are interpreted in conjunction with defects, confinement effects and near band-edge emission. Structural analysis indicate that the whiskers are all crystalline and encapsulated by a thin Si oxide layer. Infrared vibrational spectrum of Si-O-Si bondings in terms of transverse-optic (TO) and longitudinal-optic (LO) phonons indicates that disorder induced LO-TO optical mode coupling can be an effective tool in assessing structural quality of the b-Si. The same phonons are likely coupled to electrons in visible region PL transitions. Field emission properties of these nanoscopic features are demonstrated indicating the influence of the tip shape on the emission. Overall properties are discussed in terms of surface morphology of the nano whiskers

Differences in assigning probabilities to coastal inundation hazard estimators: event versus response approaches

This is the accepted version of the following article: Sanuy, M, Jiménez, JA, Ortego, MI, Toimil, A. Differences in assigning probabilities to coastal inundation hazard estimators: Event versus response approaches. J Flood Risk Management. 2020; 13 (Suppl. 1):e12557. https://doi.org/10.1111/jfr3.12557, which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/jfr3.12557.Coastal flood risk assessment requires a reliable estimation of the frequency of inundation hazards, that is, characterising the hazard magnitude and assigning a probability of occurrence. In this work we analyse the uncertainty introduced in the assessment associated to the method to assign the probability of occurrence to coastal flood hazards. To this end we have compared the use of two general methods, the response and the event approaches. Different procedures are used to characterise coastal inundation hazards depending on the analysis scale and data availability. Thus, a range of possibilities has been analysed, from simple estimators such as run-up to modelled flood-prone areas. The analysis has been performed for all wave and water level conditions around the Spanish coast. The results show that the differences between the methods are location-dependent, and thus, determined by the exposure to wave and water level conditions. When using the event approach, the run-up or total water level (with good correlation between waves and surge) distributions reasonably approximate those of the response approach with low associated uncertainty. When the assessment aims to output overtopping discharges or inundation maps, observed differences suggest that the event approach would produce misleading conclusions in inundation-related coastal management and decision-making.Peer ReviewedPostprint (author's final draft

Turbulent shear stresses in hydraulic jumps, bores and decelerating surges

In an open channel, a sudden rise in water level induces a positive surge, or bore, that may develop as a hydraulic jump in translation. When the surge propagates against an adverse slope, it decelerates until it becomes a stationary hydraulic jump. Both hydraulic jumps and decelerating surges induce some intense turbulent mixing and have some major impact on the sediment transport in natural systems. Herein, a physical investigation was conducted in a relatively large rectangular channel. Hydraulic jumps and surges were generated by the rapid closure of a gate at the channel downstream end. The turbulent shear stresses were measured with high temporal and spatial resolution (200 Hz sampling rate) in the jump flow. A comparison between the stationary hydraulic jump, hydraulic jump in translation and decelerating surge measurements showed some marked differences in terms of turbulent mixing. The results highlighted some intense mixing beneath the jump front and roller for all configurations. The levels of turbulent stresses were one to two orders of magnitude larger than a critical threshold for sediment motion. The findings provide some insights into the hydraulic jump migration processes in mobile bed channels, and the complex transformation from a moving jump into a stationary jump. Copyright (C) 2010 John Wiley & Sons, Ltd

A mathematical model for unsteady mixed flows in closed water pipes

We present the formal derivation of a new unidirectional model for unsteady mixed flows in non uniform closed water pipe. In the case of free surface incompressible flows, the \FS-model is formally obtained, using formal asymptotic analysis, which is an extension to more classical shallow water models. In the same way, when the pipe is full, we propose the \Pres-model, which describes the evolution of a compressible inviscid flow, close to gas dynamics equations in a nozzle. In order to cope the transition between a free surface state and a pressured (i.e. compressible) state, we propose a mixed model, the \PFS-model, taking into account changes of section and slope variation

Mechanical cleaning of graphene using in situ electron microscopy

Avoiding and removing surface contamination is a crucial task when handling specimens in any scientific experiment. This is especially true for two-dimensional materials such as graphene, which are extraordinarily affected by contamination due to their large surface area. While many efforts have been made to reduce and remove contamination from such surfaces, the issue is far from resolved. Here we report on an in situ mechanical cleaning method that enables the site-specific removal of contamination from both sides of two dimensional membranes down to atomic-scale cleanliness. Further, mechanisms of re-contamination are discussed, finding surface-diffusion to be the major factor for contamination in electron microscopy. Finally the targeted, electron-beam assisted synthesis of a nanocrystalline graphene layer by supplying a precursor molecule to cleaned areas is demonstrated

Establishing the database of inundation potential in Taiwan

Copyright © Springer 2006. The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-005-4659-7The structural measure was the major solution for flood defense in Taiwan. However, the measure is always limited to the design standard and cannot prevent the damages when floods exceed certain scale. Therefore, non-structural measures for flood mitigation are the indispensable complements to structural solutions. The study introduces the establishment of inundation potential database that provides required information for the non-structural measures in Taiwan. The database was built by numerical simulations, based on different rainfall scenarios, and has been applied by the local governments of Taiwan for land use managements, flood warning systems, emergency responses, and flood insurance programs to reduce the flood damages and impacts.National Science Council, Executive Yuan, ROC