A Study on the Laser Removal of Epoxy Coatings on SS400 Surface by Beam Scanning Patterns

Shipyards are very interested in improving their working environment and resolving environmental pollution issues by replacing mechanical cleaning technologies used before and after painting processes with laser cleaning technology. Because epoxy paint is thickly coated, with a thickness of 200 μm or greater, it is difficult to remove using both laser cleaning and mechanical cleaning technologies. Therefore, this study tried to obtain effective cleaning results by controlling the process parameters when removing the thick epoxy coating using a Q-switching fiber laser cleaning system with an average power of 100 W developed by our research team. The pulse duration time of the laser is 150 ns. Additionally, in order to determine whether the cleaning was sufficient, the difference in laser-induced plume/plasma was compared. By controlling the beam scanning patterns, line overlap rate, and pulse overlap rate, it was possible to obtain effective cleaning results without introducing removal deviation. In addition, the NOP increased when the laser beam overlap rate increased. This increased the amount of heat input to the material and reduced the number of scans required to remove the epoxy paint. As a result of the plume/plasma analysis, less plume/plasma was generated as the paint was removed if the epoxy paint remained on the surface. On the other hand, when all of the paint was removed, a higher brightness of plume/plasma generated by evaporation of the bare metal was observed.

Missing seashells: a subtle detail of an inadequate policy

In Santos Beach, southwest coast of Brazil, cleaning operations are intensified during the summer using manual and mechanical techniques, driven mainly by sanitary and aesthetic aspects that neglect basic ecological standards. This study evaluated the abundance, richness, and diversity of dead shells, after spring and neap tides, found in two strips of sandy beaches: the "damp" and the "wet "sectors, where only the former undergoes mechanical cleaning. We collected and counted all fragmented and whole shells, identified each down to the species levels, and measured their weight. We used mixed statistical modeling to evaluate the effect of the sector over the abundance (in weight and number), richness, and Shannon-Wiener diversity (). We found a significantly greater abundance of fragmented shells in the damp sector. Since this is the sector where mechanical cleaning is applied, we understand such a strategy promotes potential harmful impacts over the conchological structure in Santos Beach, requiring mitigatory measures to protect empty shells. Finally, we fathom incorrectly discarded litter is brought from the surrounding mangrove to the beach after the spring tides; thus, integrated cleaning management with the participation of the local population, are also required to reduce the mechanical cleaning and its impacts.

Preventing the Undesired Surface Veiling after Nanolime Treatments on Wall Paintings: Preliminary Investigations

During the last decades, the discovery of nanolime and its introduction in the field of Cultural Heritage has entailed a significant advance for the consolidation of historic wall paintings. Nevertheless, its use is not completely generalized yet within the conservation practitioner’s community due to its undesired white veiling deposit on the surface after treatment which usually covers the pictorial layer. Given the scarcity of existing literature which specify how to mitigate this undesired side-effect, the aim of this work is to carry out the first assessment of possible cleaning and treatment methods to eliminate those deposits and, at the same time, to analyse their effects on the consolidation properties. To do that, we have developed laboratory fresco wall paintings specimens. After applying an artificial ageing cycle to all of them, we consolidated them with CaloSil IP25, one of the most currently used commercial product in the practice. The elimination of the whitish deposits has been investigated with different methods: (1) wiping off the superficial excess of product immediately after each application during the treatment; (2) mechanical cleaning (scalpel) after consolidation; chemical cleaning with rigid gels of water (3), ethylenediaminetetraacetic acid (EDTA) (4) and citric acid (5) after consolidation. The effectiveness of each cleaning method has been assessed by non-destructive methods before and after the consolidation, and repeated after cleaning, by measuring differences in colour, water absorption by capillarity (i.e., sponge test), superficial adhesion (i.e., Scotch Tape Test) and by quantifying the thickness of the deposits eliminated by means of photogrammetry. Results show that both the mechanical cleaning and the removal of the excess of product after each application during the treatment yielded the most promising results for conservation practice.

ULRASONIC CAVITATION IN TREATMENT OF TROPHIC UICERS

The aim: improvement of trophic ulcer by surgical treatment with ultrasound cavitation combination. Materials and methods. The analysis of complex surgical treatment of trophic ulcers was conducted. Patients were divided into 2 groups, depending on the strategy of treatment. In the first (main) group (n=43) the combination of surgical treatment with ultrasonic cavitation was applied. By comparison, in the second group (n=43) only surgical treatment was applied. The method of treatment of trophic ulcers with the Sonoca 300 device is based on the effect of ultrasonic cavitation, which is a process of mechanical cleaning of the wound from necrotic tissues, while healthy tissue and vessels are not injured. Ultrasound machine SONOCA 300 is intended exclusively for use in human ultrasound surgery and is intended for the following applications: selective tissue dissection, mechanical grinding and cutting of bone tissue, debridement and cleaning of wounds, tissue cutting, tissue coagulation. The exact purpose of the application is determined by which tool is connected. In our case, this is a Macro ultrasonic tip designed for debridement and wound cleansing. Ultrasound is supplied at an operating frequency of 25 kHz, when you press the foot pedal, and simultaneously with the power of ultrasound, the irrigation and aspiration systems are activated. The irrigation solution from the container with the irrigation fluid passes through the tool, at the same time the aspiration of necrotic tissues and fluid, and their direction into the container for aspirate collection. Results and discussions. The ultrasonic cavitation in treatment of trophic ulcers different localization and etiological factors, achieve partial incarnation of ulcer surface on the average in (14,2±0,5) days in the first group and in (16,9±0.6) days in the second group. The level of bacterial titer of ulcer secretion by (16,5±0,6) days was not higher than the commonly accepted critical one in comparison to the classic situation, in the second group it was on the (27,2±0,9) days. Terms of inpatient treatment were: (21,2± 0,9) days in the first group and (27,2±0,9) days in the second group accordingly. The biological properties of ultrasound are due to bactericidal and bacteriostatic action on various microorganisms. In addition to its own bactericidal effect, low-frequency ultrasound significantly enhances the action of many antibiotics and antiseptics, promotes the deposition of drugs in the surface layers of the wound. Under the action of ultrasound increases the phagocytic activity of leukocytes, there is a stimulation of cellular and humeral parts of the immune system, which accelerates the wound process. Conclusion. The usage of ultrasonic cavitation in the complex surgical treatment of trophic ulcers different localization and etiological factors, significantly increases the time of trophic ulcer cleaning, accelerates incarnation by 1.2, reduce the time of treatment of patients with trophic ulcers by 1.8 times in comparison to the classical approach of cleaning, by means of mechanical cleaning of the ulcers from purulence and necrotic tissue by ultrasound of low frequency.

PONTOON SETTLEMENTS AS A MEANS OF RESTORING THE ECOLOGICAL BALANCE OF RESERVOIRS

The article considers the influence of pontoon settlements on the ecology of reservoirs of Ukraine. The main types of pollution and methods of reservoir cleaning due to the creation of pontoon settlements are outlined. There are 1157 reservoirs located within Ukraine. The issue of efficient and rational use of reservoirs in Ukraine is becoming increasingly important. The establishment of settlements on the water could help solve the environmental problems present in reservoirs. Reservoir pollution can be divided into chemical, bacterial, thermal and radioactive. Chemical pollution is the ingress of various chemicals, waste from various industries into the water: petrochemical, pulp and paper, as well as municipal wastewater, waste from livestock farms. Biological pollution is getting into reservoirs together with sewage of various pathogenic microorganisms, spores of fungi, worms. Thermal pollution occurs due to the discharge of heated water from thermal power plants, nuclear power plants and other energy facilities. Radioactive contamination is associated with an increase in the content of radioactive substances in water. When designing pontoon settlements in the water area of reservoirs, it is necessary to provide mechanical cleaning methods. Mechanical cleaning is the cleaning of the bottom of the reservoir from large objects of various origins, as well as the removal of large accumulations of benthic and floating species of aquatic plants. The basis of the biological method of purification is the saturation of the reservoir with microorganisms (bacteria). Another very effective way is to stock the ponds with herbivorous species. Such fish species as silver carp, carp, grass carp, pike, pike perch are biological reclamation of reservoirs. The basis of the chemical method of purification is the addition of special reagents of varying composition to the reservoir. The main way to reduce thermal pollution is the gradual abandonment of fossil fuels and the transition to renewable energy using solar energy sources: light, wind and water resources. To ensure all methods of cleaning reservoirs, it is necessary to create specialized floating platforms (pontoons) when designing pontoon settlements. On them it is possible to place bases for service of technical fleet (special equipment), various technological equipment; platforms for placement of chemical reagents; fish farming platforms for biological treatment; sorting, temporary storage and processing of garbage, etc. Platforms must be modular, mobile, easy to transport, have mechanical strength and high load capacity. They can also be stationary and mobile, self-propelled and non-self-propelled depending on the functional load and floor-plate of the pontoon settlement. Pontoon settlements that are developed according to all the respective laws, norms and rules can be considered effective means of combating pollution of reservoirs and help restore their environmental resources.

Closed ventilation and filtering system for cleaning of welding aerosols at deposition

In the article the questions of development of construction of the closed ventilation and filtering system (CVFS) are considered on cleaning of air-gas mixture at deposition. The offered system consists of gas in-take, filters, containers for assembling of hard parts, hard constituent of welding aerosol (TSSA), by the gaseous constituent of welding aerosol (GSSA) and corps, special vent system with adjusting of speed and volume of extraction. Conducted research for cleaning of welding aerosols (SA) at deposition of high wear proof alloys of type of sormite with the use of the CVFS. Special CVFS is used, filters in particular mechanical, electric, chemical (sorption). Extraction of air-gas mixture from the area of melting of electrode and welding bath of is carried out by the pipe of small diameter, with adjusting of speed and volume of extraction passes the system of filtration the special vent system where clears up from TSSA. Thus cleared gas mixture is used as gas defense at depositing. It is necessary it is not simple to catch SA, but to filter in the closed system, clean and give filtered clean y air in the area of deposition, technology and metallurgical properties of process of depositing must not be broken here. Features of the mechanical cleaning are in technologies of deposition, characterized that air-gas mixture has a temperature which influences on a sorbent. The mechanical cleaning by the centrifugal chamber of cleaning (CCC) is the modernized cyclone filter where centrifugal forces and gravities were used. Differs from existent cyclic filters a presence by a conical spiral insertion and rearranged surface of cone which engulfs it. In the entrance tangential union coupling appears, divided aero mixture into a few streams of entered in a spiral insertion. In the electric filter (electrostatic) electric forces operate on particles and gas molecules (based on the phenomena ionization of gas molecules, by an electric charge in the electric field). An electric charge is revealed to the particles, and they under the action of the electric field are besieged from a gas stream. If such gas, containing the several of transmitters of charges, to place between electrodes, connected with the source of high voltage, ions and electrons will begin to move to on power the field lines . This is important during neutralization of GSSA

Enzymatic biofilm destabilisation to support mechanical cleansing of inserted dental implant surfaces: an in-vitro pilot study

Peri-implantitis is caused by microbial contamination and biofilm formation on the implant surface. To achieve re-osseointegration, the microbes must be completely removed from the surface. Adjunctive to mechanical cleaning, chemical treatment with enzymes or other substances could optimise the treatment outcome. Therefore, we investigated the efficacy of different enzymes, a surfactant, and a chelator in destabilising dental polymicrobial biofilm. The biofilm destabilising effect of the glycosidases α-amylase, dextranase, DispersinB®, and lysozyme, as well as the proteinase subtilisin A, and the nuclease Benzonase®, the chelator EDTA, and the surfactant cocamidopropyl betaine were investigated on biofilms, inoculated with plaque on rough titanium discs. The test and the control solutions were incubated for 15 min at 36 °C on biofilms, and loosened biofilm mass was removed by shear stress with a shaker. Fluorescence-stained biofilms were microscopically analysed. Acceptable cell tolerability concentrations of test substances were determined by the MTT (tetrazolium dye) assay on the MG-63 cell line. A statistically significant biofilm destabilising effect of 10% was shown with lysozyme (2500 µg/ml).

WATER TREATMENT BY AN INTEGRATED METHOD FOR OPERATION OF WATER BOILERS AND HEATING NETWORKS

The use of a complex fi lter for water treatment is proposed for the fi rst time. The complex fi lter includes two layers. The fi rst layer along the course of the water should be loading for mechanical cleaning, the second - for softening (ion exchange). Cleaning can be one- or two-stage. For research, water was used from three wells in the Samara region. In the course of the work, two stages of laboratory research were carried out, on the basis of which the best fi ltering load was determined. The calculation of the total and working exchange capacity has been made. A technical and economic comparison of cleaning methods was carried out. The results of the work performed were summed up, proposals were made for the rational use of installations and the prospects for the development of the work in the future were determined.