Mission planning for repeated multi-spacecraft non-contact debris removal

Aim: This study compared smear-layer and debris removal using with three different application times of 17% EDTA and 7% maleic acid irrigation agents.
 Methodology: Fifty-two maxillary and mandibular single-rooted teeth were divided randomly into seven groups (n = 8 each, control group n = 4). Three groups received 17% EDTA and three received maleic acid (1, 5, 10 min). Canals were prepared using nickel-titanium rotary files. Smear-layer and debris removal were evaluated in the coronal, middle, and apical thirds of the teeth using scanning electron microscopy, and results were analyzed compared using Mann–Whitney U tests.
 Results: Maleic acid removed the smear layer (coronal and middle: p<0.01; apical: p<0.05) and debris (all p< 0.05) more effectively than EDTA in terms of 1 min application period. Effectiveness did not differ significantly with 10-min applications.
 Conclusions: Final irrigation with 7% maleic acid is more efficient than 17%EDTA in the removal of smear layer and debris from the coronal, middle and apical third of the root canal system in application within 1 min. 
 How to cite this article: Kaya S, Adıgüzel Ö, Ganidağlı Ayaz S. Effectiveness of Three Different Application Times of 17% EDTA and 7% Maleic Acid Irrigation Agents on the Removal of Debris and Smear Layer: A Scanning Electron Microscope Study. Int Dent Res 2011;2:48-54.
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Background:A successful endodontic treatment depends on efficient cleaning and shaping and effective irrigation of root canals. The irrigating solution may not be effective in some areas in the canal. The manufacturer of XP-Endo finisher claims that it can effectively clean the root canals with complex morphology. This study aimed to assess the effect of XP-Endo finisher on the amount of residual debris and smear layer on the root canal walls of mandibular second premolars.Materials and Methods:In this In vitro study Fifty extracted mandibular second premolars with a root curvature <20° were collected. Root canals were prepared using BioRaCe rotary system. The root canals were in contact with the file and different irrigating solutions for 1 min. The teeth were then randomly divided into four experimental (n = 10) and one positive control group as follows: (1) XPF + saline, (2) XPF + ethylenediaminetetraacetic acid (EDTA), (3) XPF + sodium hypochlorite (NaOCl), (4) XPF + EDTA + NaOCl and (control) EDTA + NaOCl. The teeth were longitudinally sectioned into two halves and the amount of debris and smear layer remaining in the coronal, middle, and apical thirds of the roots was quantified and scored under an electron microscope. The Kruskal–Wallis test was used to compare the groups, and P < 0.05 was considered statistically significant.Results:The highest mean amount of residual debris (2.9 ± 1.13) was noted in XPF + saline group (P < 0.05). XPF + saline and XPF + NaOCl (3.8 ± 0.60) had the lowest efficacy for smear layer removal (P < 0.05) with no significant within-group difference. No significant difference was noted between Groups 2, 3, and 4 with the positive control group regarding debris removal. Groups 2 and 4 had no significant difference with the positive control group regarding smear layer removal.Conclusion:Use of XP-Endo finisher has no superiority to the standard protocol for the use of irrigating solutions (EDTA + NaOCl) for debris and smear layer removal, but in some cases, such as second appointment of regeneration treatment we cannot use NaOCl because of its destructive effects on stem cells; thus, we can benefit from the synergistic effects of XPF and EDTA for better smear layer removal.

Accumulation of ablation debris particles interferes with femtosecond laser micromachining of high-aspect ratio grooves in metal. Debris removal from such grooves by an air or inert gas jet requires that the gas jet axis be aligned with the groove. This requirement constrains the motion system design and programming as well as the gas nozzle design for cutting of arbitrary shapes. Gas jet debris removal is also not feasible in vacuum environments. In this study, a novel technique based on DC-dielectrophoresis (DEP) for removing debris from the cut groove was investigated. Femtosecond laser ablation of linear and circular grooves from thick sections of aluminum was performed with no debris removal and with debris removal by air jet or DC-DEP force. Ablation depth and precision were compared for the three experimental conditions. Debris removal by DC-DEP force resulted in the most accurate, consistent, and orientation-independent machining of high-aspect ratio grooves. Moreover, larger electric fields exerted stronger DC-DEP force on debris particles and resulted in better ablation precision and machining rate.

Introduction: The aim of this study was to systematically review the debridement efficacy of ultrasonic irrigation compared with sonic irrigation during the endodontic treatment. Methods: An electronic search was undertaken on Cochrane Library, Medline, ScienceDirect and Scopus for articles published between January 2010 and January 2021 using appropriate Mesh terms and key words. The inclusion criteria were systematic reviews or in vitro controlled trials on permanent mature teeth or models simulating the root canal system involving a sonic or ultrasonic irrigation group and a control group of conventional needle irrigation. Two reviewers independently selected articles to include according to the inclusion criteria, extracted data from the articles and assessed the methodological quality of the included studies. The data items were arranged in tables. Results: From 811 studies, 17 in vitro studies and 3 systematic reviews were included. EndoActivator and EDDY were the most sonic devices used, whereas several ultrasonic devices were tested for passive ultrasonic irrigation. Debris removal was assessed either on root canal walls or isthmuses or both. The risk of bias and quality of the selected studies were qualified as moderate to high according to the JBI (Joanna Briggs Institute) and the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) checklists. Overall, the findings confirmed superiority of the two agitation techniques over conventional irrigation and most of the studies showed no significant differences between sonic and ultrasonic irrigation in debris removal, however a moderate level of evidence showed superiority of ultrasonic irrigation. Conclusion: It may be concluded that sonic and ultrasonic activation of the irrigants are beneficial in hard tissue debris removal when compared to conventional needle irrigation, yet, the current data could not find significant differences between the two techniques.

In the United States, debris removal is one of the costliest and most time-consuming elements of disaster response and recovery. It is essential to reducing secondary environmental and health risks, and to community recovery and rebuilding. Analysis of debris removal and waste management, though, primarily treats it as a series of operational steps and technical decisions. In contrast, this article analyses disaster debris removal decision-making as a social process. We present the findings of an ethnographic study that engaged over 70 government actors from federal, state, local, and Tribal agencies in focus groups and interviews. By examining the experiences of these actors, who are central to debris removal decisions, this article identifies decision points that send waste down particular pathways from collection to final disposal. Three operational areas of concern that emerge from the analysis are: local control and capacity, cost and reimbursement, and balance between urgency and sustainability. This article shows how social processes in particular socio-material systems shape these decisions, such as the interplay of waste and disaster institutional arrangements. Finally, it shares practical implications for social process workarounds to operational challenges, such as interagency and interlevel relationships, that can support on-the-ground decision-making.

Debris removal is a critical activity in the aftermath of natural disasters such as earthquakes and tsunamis to enable community and lifeline network recovery. This activity is hampered by logistical bottlenecks including the non-availability of equipment and inadequate capacity of temporary debris management sites (TDMS). This paper enables analysis of debris removal and lifeline repair operations quantifying recovery times for informed decision-making about equipment allocation and TDMS selection before the disaster. The developed framework was applied to the case study of a Cascadia Subduction Zone event for the coastal town of Astoria in Oregon. The proposed framework enables decision-makers with an objective means of evaluating decision alternatives both before and after disasters to analyze and improve their community’s capability of handling disaster debris. Furthermore, this framework will serve as a platform upon which interdependencies between transportation network and debris removal operations will be analyzed in the future.

Chapter 5 - Removal of Large Space Debris by a Tether Tow

The international legal aspects of operations for active removal of space debris (SD) from near-Earth space (NS) are considered. An analysis is made of the factors determining the responsibility of launching states for damage caused by their space means to other participants in space activities (SA). Attention is focused on the need to develop the legal framework for the implementation of commercial projects in outer space.The international legal aspects of operations for active removal of space debris (SD) from near-Earth space (NS) are considered. An analysis is made of the factors determining the responsibility of launching states for damage caused by their space means to other participants in space activities (SA). Attention is focused on the need to develop the legal framework for the implementation of commercial projects in outer space.

ABSTRACTIntroduction:An instrumented and endodontically treated tooth may sometimes impede disinfection by trapping hard tissue as well as the other canal contents at the isthmus level of the canal. Thus, the current in vitro study was piloted to assess the competence of two irrigating systems.Methods:Twenty mandibular with two mesial canals convergent into a single foramen and joined by an isthmus of the human permanent teeth were compared for the two irrigation systems of continuous and intermittent ultrasonic (US) motions of the irrigation. The teeth were prepared by a single rotary system and were imaged using the “Scanning electronic microscopy-SCM”. The parameters were compared before and after the irrigation of the canal with the intended US systems for the removal of hard tissue debris. The appropriate statistical tools were used to find the significance, the value of which was kept at P < 0.05.Results:Significant percentage reduction of the hard tissue debris was achieved after the application of the supplemental irrigation protocols (P < 0.05). However between the groups, there was no significant difference.Conclusions:Comparable removal of the hard tissue debris was obtained in both the irrigation systems. Though not significant, the GentleWave performed better than the Irrisafe.

Accumulation and concentration of debris in deep hole electrical discharge machining (EDM) significantly hinder its machining efficiency and accuracy. It is believed that the movement of bubbles associated with the discharge gap flow field play a pivotal role in debris removal and influence the discharge conditions. Ultrasonic vibration (USV) of the electrode is thought to be an effective method for improving EDM-generated bubbles and debris exclusion. In this study, we first elucidated the behavior of bubbles during EDM of holes with varying aspect ratios. Subsequently, USV was introduced to EDM. The behavior of dielectric fluid flow under the influence of ultrasonic vibration was analyzed using computational fluid dynamics (CFD), which revealed time-varying changes in discharge gap flow pressure and velocity. The velocity of the dielectric flow field near the electrode's side face was found to reach a maximum of approximately 15.2 m/s, greatly facilitating debris removal. High-speed camera observations revealed that bubbles were dispersed within the side gap, with most of them adhering to the electrode's wall. Furthermore, the bubbles exhibited a tendency to continuously break up and coalesce near the hole's outlet before escaping in the USV-assisted EDM. These observed characteristics of bubble behavior under the influence of USV are expected to significantly enhance debris removal and promote efficient dielectric exchange.

Solution methodologies for debris removal in disaster response

Hurricane Katrina struck the Gulf Coast as a Category 3 storm on August 29th of 2005. It is the costliest natural disaster in U.S. history. Communities across the country are increasingly at risk of being affected by natural and environmental disasters. The Public Assistance Grant Program (PA Program) administered by the Federal Emergency Management Agency (FEMA) is available for states and communities that have received a major or emergency disaster declaration. Most of Emergency Management (EM) research has focused on preparedness and mitigation activities; considerably less research has studied post disaster response. Two of the initial and most important aspects of disaster response and recovery operations are the removal and disposal of debris from the disaster-affected area. This study assesses local government’s debris removal management decisions and how they impact their net wealth in the long run by using local government financial data from audited financial statements and post disaster data from the Louisiana Public Assistance database. Variables from transaction cost theory and similarity hypothesis are included as right hand side variables to explain the choice of outsourcing versus internal procurement of debris removal. A System Dynamics model is then built using the regression results and it incorporates debris removal decisions in the context of assumptions about future storm characteristics (i.e. frequency and severity) as well as the current capital and debt financial accounts of a rural parish government in Louisiana.

The study examines the influence of various process parameters on Material Removal Rate (MRR), Tool Wear Rate (TWR) AND Surface Roughness (Ra) during the machining of Hastelloy using Electrical Discharge Machining (EDM) machined under NaOH dielectric medium. Results showed that a 20% NaOH concentration optimizes MRR at 0.889 mm3 min−1, while higher concentrations lead to process instability due to excessive bubble formation and discharge irregularities. The optimal current of 30 A improves MRR, but excessive melting occurs beyond this level, negatively impacting tool wear and surface finish. A pulse-on time of 45 μs produces the best surface finish of 1.786 μm), while longer pulse durations cause overheating and degrade surface quality. TWR was minimized at a gap distance of 2 mm, which allowed effective cooling and debris removal, reducing wear by 15%. Voltage levels between 12 V and 18 V resulted in the most stable discharges, yielding optimal MRR and Ra values. Lower current values stabilize TWR, while higher currents and longer pulse-on times increase wear. A gap distance of 2 mm minimizes TWR by ensuring effective cooling and debris removal. Optimal surface roughness is achieved with 30 A and 45 μs, where controlled discharges reduce surface imperfections. Higher NaOH concentrations induce rougher textures due to more aggressive sparks. SEM analysis confirms that process parameters significantly impact surface topography, characterized by craters, re-solidified debris, and microcracks. The optimized parameters identified from the results were 20% NaOH concentration, 30 A current, 45 μs pulse-on time, 2 mm gap distance, and voltage of 15 V.

An analysis of cost savings that could be realized on active debris removal (ADR) missions through the use of reusable launch vehicles (RLVs) has been performed. Launch vehicle price estimates were established for three levels of RLV development, based on varying levels of technological development and market competition. An expendable launch vehicle (ELV) price estimate was also established as a point of comparison. These price estimates were used to form two separate debris removal mission cost estimates, based on previously proposed debris removal mission concepts. The results of this analysis indicate that RLVs could reduce launch prices to levels between 19.6% and 92.8% cheaper than ELVs, depending on the level of RLV maturity. It was also determined that a RLV could be used to realize total ADR mission cost savings of between 2.8% (for a partially RLV in an uncompetitive market) and 21.7% (for a fully RLV in a competitive market).

A multi-platform active debris removal mission planning method based on DCOP with chain topology