Antibacterial Activity of Calcium Hydroxide Combined with Chlrohexidine or Sodium Hypochlorite against Gram Positive and Gram Negative Bacteria

The most significant current goal in endodontology is the maximum reduction of the microorganisms because they play a fundamental role in the etiology of pulpo-periapical pathosis and may escape from tooth and circulate throughout the body to cause an infection in distant part. Numerous materials have been used to achieve this goal. Calcium hydroxide [Ca(OH)2]with its unique properties, need to be mixed with other agents to fulfill its antimicrobial requirement. However, to the best of authors knowledge , no report has been found so far investigates the antimicrobial efficacy of Calcium hydroxide / chlorhexidine [CHX ]combination  against  klebsiella spp..The aim of this study is to evaluation of the effect of adding CHX or sodium hypochlorite[NaOCl] on the antibacterial activity of Ca(OH)2 against gram positive and gram negative bacteria. The tested samples were grouped into 5 groups of 20 samples for each group: G1:Ca(OH)2  mixed with H2O. G2:2% CHX solution. G3: 2.5% NaOCl solution. G4: combination of Ca(OH)2   and 2% CHX. G5:combination of Ca(OH)2  and  2.5% NaOCl. 10 samples from each group had been inoculated with streptococcus spp. and the other 10 had been inoculated with klebsiella spp. Microbial growth was verified and number of plates which show growth or no growth for bacteria were counted and analyzed statistically. As a result Ca(OH)2  and 2.5% NaOCl had antibacterial effect on both tested bacteria while 2% CHX appeared to be less effective . Pastes of Ca(OH)2   and 2% CHX were effective on klebsiella spp., while mixing of Ca(OH)2 with 2.5% NaOCl had significant effect on both types of bacteria and it was more effective against streptococcus spp. Key words: Calcium hydroxide, Chlorhexidine, Sodium hypochlorite, klebsiella, Streptococcus

Systematic study of aqueous monoethanolamine-based CO2 capture process: model development and process improvement

In this paper, we present improvements to postcombustion capture (PCC) processes based on aqueous monoethanolamine (MEA). First, a rigorous, rate-based model of the carbon dioxide (CO2) capture process from flue gas by aqueous MEA was developed using Aspen Plus, and validated against results from the PCC pilot plant trials located at the coal-fired Tarong power station in Queensland, Australia. The model satisfactorily predicted the comprehensive experimental results from CO2 absorption and CO2 stripping process. The model was then employed to guide the systematic study of the MEA-based CO2 capture process for the reduction in regeneration energy penalty through parameter optimization and process modification. Important process parameters such as MEA concentration, lean CO2 loading, lean temperature, and stripper pressure were optimized. The process modifications were investigated, which included the absorber intercooling, rich-split, and stripper interheating processes. The minimum regeneration energy obtained from the combined parameter optimization and process modification was 3.1 MJ/kg CO2. This study suggests that the combination of a validated rate-based model and process simulation can be used as an effective tool to guide sophisticated process plant, equipment design and process improvement

Stakeholder perspectives on primary school pupils and sickness absence:Exploring opportunities and challenges

School absenteeism and its underlying causes can have negative effects on the cognitive, psychosocial and health development of a child. Research in primary education shows high rates of sickness absence. Many stakeholders are involved in addressing school absenteeism, including primary school professionals, child and youth healthcare physicians, school attendance officers and parents. This study explores these stakeholders’ perspectives, their approaches and what they envisage to be necessary in order to improve. It also aims to unveil opportunities and challenges in addressing sickness absence among primary school pupils. Qualitative research was performed with six semi-structured focus group interviews and involving 27 participants from the West-Brabant and Amsterdam regions of the Netherlands. Thematic analysis was used. The overarching theme was aiming for the child’s wellbeing. Each focus group interview started with low awareness of sickness absence as a threat to this wellbeing, but awareness grew during the interviews. The participating stakeholders regarded problematic sickness absence as complex due to a wide variety of causes, and felt that each other’s expertise was necessary to reduce sickness absence. Schools registered absence, but only occasionally used planned steps; they based the identification of problematic sickness on gut feeling rather than any agreed-upon criteria. To be able to systematically address sickness absence and thus improve the wellbeing of children, stakeholders felt the need for a clearly structured approach, including monitoring of sickness absence of all pupils, identifying problematic absence and promoting collaboration with other stakeholders. An approach should allow for tailoring solutions to the individual child

Existing and Required Modeling Capabilities for Evaluating ATM Systems and Concepts

ATM systems throughout the world are entering a period of major transition and change. The combination of important technological developments and of the globalization of the air transportation industry has necessitated a reexamination of some of the fundamental premises of existing Air Traffic Management (ATM) concepts. New ATM concepts have to be examined, concepts that may place more emphasis on: strategic traffic management; planning and control; partial decentralization of decision-making; and added reliance on the aircraft to carry out strategic ATM plans, with ground controllers confined primarily to a monitoring and supervisory role. 'Free Flight' is a case in point. In order to study, evaluate and validate such new concepts, the ATM community will have to rely heavily on models and computer-based tools/utilities, covering a wide range of issues and metrics related to safety, capacity and efficiency. The state of the art in such modeling support is adequate in some respects, but clearly deficient in others. It is the objective of this study to assist in: (1) assessing the strengths and weaknesses of existing fast-time models and tools for the study of ATM systems and concepts and (2) identifying and prioritizing the requirements for the development of additional modeling capabilities in the near future. A three-stage process has been followed to this purpose: 1. Through the analysis of two case studies involving future ATM system scenarios, as well as through expert assessment, modeling capabilities and supporting tools needed for testing and validating future ATM systems and concepts were identified and described. 2. Existing fast-time ATM models and support tools were reviewed and assessed with regard to the degree to which they offer the capabilities identified under Step 1. 3 . The findings of 1 and 2 were combined to draw conclusions about (1) the best capabilities currently existing, (2) the types of concept testing and validation that can be carried out reliably with such existing capabilities and (3) the currently unavailable modeling capabilities that should receive high priority for near-term research and development. It should be emphasized that the study is concerned only with the class of 'fast time' analytical and simulation models. 'Real time' models, that typically involve humans-in-the-loop, comprise another extensive class which is not addressed in this report. However, the relationship between some of the fast-time models reviewed and a few well-known real-time models is identified in several parts of this report and the potential benefits from the combined use of these two classes of models-a very important subject-are discussed in chapters 4 and 7

Wet deposition in the remote western and central Mediterranean as a source of trace metals to surface seawater

Abstract. This study reports the only recent characterization of two contrasted wet deposition events collected during the PEACETIME (ProcEss studies at the Air–sEa Interface after dust deposition in the MEditerranean Sea) cruise in the open Mediterranean Sea (Med Sea) and their impact on trace metal (TM) marine stocks. Rain samples were analysed for Al, 12 TMs (Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrient (N, P, dissolved organic carbon) concentrations. The first rain sample collected in the Ionian Sea (Rain ION) was a typical regional background wet deposition event, whereas the second rain sample collected in the Algerian Basin (Rain FAST) was a Saharan dust wet deposition event. Even in the remote Med Sea, all background TM inputs presented an anthropogenic signature, except for Fe, Mn and Ti. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, due to the decrease in anthropogenic emissions during the preceding decades. The atmospheric TM inputs were mainly dissolved forms, even in dusty Rain FAST. The TM stocks in the mixed layer (ML, 0–20 m) at the FAST station before and after the event showed that the atmospheric inputs were a significant supply of particulate TMs and dissolved Fe and Co for surface seawater. Even if the wet deposition delivers TMs mainly in soluble form, the post-deposition aerosol dissolution could to be a key additional pathway in the supply of dissolved TMs. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as ML stocks for dissolved Fe, Co and Zn, highlighting the role of the atmosphere in their biogeochemical cycles in the stratified Med Sea. In case of intense dust-rich wet deposition events, the role of atmospheric inputs as an external source was extended to dissolved Co, Fe, Mn, Pb and Zn. Our results suggest that the wet deposition constitutes only a source of some of dissolved TMs for Med Sea surface waters. The contribution of dry deposition to the atmospheric TM inputs needs to be investigated.</jats:p

The Peculiar Type Ia Supernova 2005hk

We present a preliminary analysis of an extensive set of optical observations of the Type Ia SN 2005hk. We show that the evolution of SN 2005hk closely follows that of the peculiar SN 2002cx. SN 2005hk is more luminous than SN 2002cx, while still under-luminous compared to normal Type Ia supernovae. The spectrum at 9 days before maximum is dominated by conspicuous Fe III and Ni III lines, and the Si II 6355 line is also clearly visible. All these features have low velocity (~6000 km/s). The near maximum spectra show lines of Si II, S II, Fe II, Fe III, as well as other intermediate mass and iron group elements. Analysis with the code for synthetic spectra SYNOW indicates that all these spectral lines have similar velocities.Comment: 6 pages, 3 figures, submitted to the proceedings of the conference``The Multicoloured Landscape of Compact Objects and their Explosive Origins'', 2006 June 11--24, Cefalu, Sicily, to be published by AI

Gut microbiota-derived propionate reduces cancer cell proliferation in the liver

Peer reviewedPublisher PD

Simultaneous heat and water recovery from flue gas by membrane condensation: experimental investigation

A tubular ceramic membrane is investigated as the condenser for simultaneous heat and water recovery from flue gas. The effects of the operational parameters, such as fluid (gas and water) flow rates, temperatures of flue gas and coolant water, and flue gas humidity on the process performance in terms of mass and heat transfer across the membrane are studied. Particularly, the overall heat transfer coefficient is also evaluated. As the gas flow rate increases, water and heat transfer efficiencies and recoveries decline due to the reduced residence time. Increasing the water flow rate or lowing the coolant temperature can effectively improve mass and heat transfer efficiencies and recoveries. Increasing the temperature of the inlet gas can enhance water and heat fluxes and recoveries, but does not improve the overall heat transfer efficiency. The rise in flue gas humidity can dramatically improve water and heat transfer rates and the overall heat transfer coefficient, but has little effect on water and heat recoveries. These results offer a general guideline in optimising the operational parameters in low-grade heat recovery with membrane heat exchangers, and it may greatly advance the development of membrane condensation technology for practical low-grade heat recovery