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

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1510
Author(s):  
Ji-Eon Kim ◽  
Jong-Myoung Lee ◽  
Jeong-Hun Hyun ◽  
Je-Han Jeong ◽  
Jong-Do Kim
Keyword(s):  
Average Power ◽  
Laser Cleaning ◽  
Working Environment ◽  
Beam Scanning ◽  
Before And After ◽  
The Difference ◽  
Cleaning Technology ◽  
Overlap Rate ◽  
Epoxy Paint ◽  
Mechanical Cleaning

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.

scholarly journals Omissions in the disinfection of a craft-slaughterhouse

2018 ◽  
Vol 34 (1) ◽  
pp. 107-117
Author(s):  
Ljiljana Jankovic ◽  
Radislava Teodorovic ◽  
Marijana Vucinic ◽  
Stefan Pintaric ◽  
Milutin Djordjevic ◽  
...  
Keyword(s):  
Study Material ◽  
Before And After ◽  
Disinfection Procedure ◽  
Previously Treated ◽  
The Difference ◽  
Number Of Bacteria ◽  
Total Bacteria ◽  
Mechanical Cleaning ◽  
Exposition Time

The aim of this study was to establish the difference in the total number of bacteria present on some surfaces after disinfection was performed either by a professional or a layman employed at the slaughterhouse. Based upon the obtained results it can be concluded that there were omissions in the disinfection procedure. The study material consisted of wet and dry swabs taken during a five week period, before and after disinfection was performed either by a professional or a laymen. The following surfaces were sampled: meat carving knife, meat hooks, floor of the stunning area, and corridor floor. The procedure for wet swabs was carried out in accordance with the standard ISO 18593 method. The number of bacteria was estimated from each sample with the standard ISO 4833 method. Disinfection was performed with a 0.02% chlorine solution; the exposition time was 30 min. According to the obtained results it can be concluded that after disinfection was carried out by a professional- veterinarian, or by a layman, all surfaces which were previously treated correctly (mechanical cleaning and sanitary washing), and disinfected measured a significant decrease in the number of total bacteria (log cfu/cm2). The results for the total number of bacteria obtained after disinfection of the stunt area indicate on possible omissions as the number of bacteria did not decrease.

Corrosion Resistance of Copper Sheet after Laser Treatment

2015 ◽  
Vol 227 ◽  
pp. 167-170 ◽  
Author(s):  
Tomasz Onyszczuk ◽  
Marta Zwolińska ◽  
Marta Mazurkiewicz ◽  
Jan Marczak ◽  
Antoni Sarzyński ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Room Temperature ◽  
Treatment Process ◽  
Laser Cleaning ◽  
Copper Corrosion ◽  
Nacl Solution ◽  
Copper Sheet ◽  
X Ray ◽  
Before And After ◽  
Cleaning Technology

This study concerns laser cleaning technology and its impact on copper corrosion resistances. The results of the treatment process were analyzed after irradiation at various laser powers and scanning velocities of the laser beam. The corrosion resistance of copper sheets, before and after laser irradiation, was examined in an NaCl solution at room temperature. Investigations included surface topography observations using a scanning electron microscope (SEM) together with chemical and phase composition determined by energy dispersive X-ray spectrometry (EDS) and Raman spectroscopy.

scholarly journals Perbedaan Tekanan Darah Sebelum dan Sesudah Terpapar Tekanan Panas (Studi pada Pekerja di Pabrik Tahu Bu Lis di Kec. Donorejo Kab. Pacitan tahun 2017)

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Novi Nur Pratiwi ◽  
Winarko . ◽  
Narwati .
Keyword(s):  
Blood Pressure ◽  
Data Retrieval ◽  
Threshold Value ◽  
Cross Sectional Study ◽  
Working Environment ◽  
Physical Factors ◽  
Climate Control ◽  
Cross Sectional ◽  
Before And After ◽  
The Difference

ne"> A comfortable work environment, one of which can be seen from the physical factors in the working environment, especially in the aspect of the working climate (heat-pressure). The working climate (heat-pressure) in the workplace can affect the health of the workforce that will ultimately decrease productivity. According to the research results of Ari, Suwondo and coauthors in 2008, that the pressure the heat affect the workers blood pressure. Tofu factory belonging to the "Ibu Lis" is the manufacturer knew the only residing in Donorojo Subdistrict of Pacitan Regency. The results of measurements on a preliminary survey of the working climate in 3 point at the production of known average temperature 31,28 ºC. These results show has exceeded the threshold Value (NAB) based on the regulation of the Minister of Manpower and Transmigration Number PER 13/DOWNLOAD/X/2011 about the value of the thresholdfFactors are physical and chemical factors in the workplace amounted to 25.9 °C so that it can have an effect on the health of workers, in particular the blood pressure. In general, this research aims to know the difference in blood pressure before and after exposure to heat pressure on workers at Lady Lis’s tofu factory Donorojo Subdistrict of Pacitan Regency and in particular aiming to identify the characteristics of the workforce, the employment climate measure, measure the blood pressure of the workers before and after work, analyzing the difference of blood pressure before and after exposure to heat pressure, described the influence of characteristics of workers against blood pressure and climate control efforts work in the factory. This research includes the kind of observational studies and timebased data retrieval include cross sectional study. A large sample of 30 people taken in random, data is collected and processed and analyzed statistically (analytic) to test the hypothesis. The results showed there was a difference in blood pressure before and after exposure to heat pressure. Blood pressure changes also affected the characteristics of workers, among others, age, period of employment, and the habit of exercising. Factory owners are advised to install the ventilation is natural or manmade in the form vetilasi giving a fan or exhauster, workers should be more drinking lots of water, and take advantage of the break well. Key words : heat pressure, blood pressure, tofu factory

scholarly journals Laser cleaning of Cu-based artefacts: laser/corrosion products interaction

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 104 ◽  
Author(s):  
Elisabetta Di Francia ◽  
Ruth Lahoz ◽  
Delphine Neff ◽  
Emma Angelini ◽  
Sabrina Grassini
Keyword(s):  
Laser Cleaning ◽  
Corrosion Products ◽  
X Ray Diffraction ◽  
Cleaning Procedure ◽  
Before And After ◽  
Archaeological Artefact ◽  
The Difference ◽  
Experimental Findings ◽  
Optimized Conditions ◽  
Reference Samples

<p class="Abstract">This study aims to develop a low invasive and selective laser cleaning procedure for the removal of reactive corrosion products on Cu-based artefacts without damage the substrate. In a preliminary step, laser cleaning was performed on two typologies of artificially corroded copper reference samples. The effect of the variation of laser parameters as pulse duration and output power, was thus evaluated on an oxide layer, simulating a protective patina, and a hydroxychloride layer, simulating a reactive corrosion products layer to be removed. The optimized cleaning procedure was validated on an archaeological artefact, a bronze coin. Morphological, microchemical and microstructural characterizations were performed by means of optical microscopy, confocal microscopy, field emission scanning electron microscopy, X-Ray diffraction and Raman spectroscopy, before and after laser cleaning. The experimental findings show that laser cleaning, in optimized conditions, can reduce the thickness of the hydroxychloride layers slightly affecting the oxide layers. The difference in the interaction with laser radiation of these two layers seems to be mainly related to the difference in grain size and porosity. Notwithstanding these encouraging results, in order to define the real feasibility of the laser cleaning procedure, a further validation on real artefacts is mandatory due to the variation in thickness and composition of the corrosion products formed during long-lasting uncontrolled degradation processes.</p>

The genotoxic effects in the leukocytes of workers handling nanocomposite materials

Mutagenesis ◽  
2020 ◽  
Vol 35 (4) ◽  
pp. 331-340 ◽  
Author(s):  
Bozena Novotna ◽  
Daniela Pelclova ◽  
Andrea Rossnerova ◽  
Vladimir Zdimal ◽  
Jakub Ondracek ◽  
...  
Keyword(s):  
Dna Damage ◽  
Working Environment ◽  
Genotoxic Effects ◽  
Potential Health ◽  
Endonuclease Iii ◽  
Personal Exposures ◽  
Ficoll Gradient ◽  
Increased Risk ◽  
Before And After ◽  
The Difference

Abstract The extensive development of nanotechnologies and nanomaterials poses a number of questions to toxicologists about the potential health risks of exposure to nanoparticles (NP). In this study, we analysed DNA damage in the leukocytes of 20 workers who were long-term exposed (18 ± 10 years) to NP in their working environment. Blood samples were collected in September 2016, before and after a shift, to assess (i) the chronic effects of NP on DNA (pre-shift samples) and (ii) the acute effects of exposure during the shift (the difference between pre- and post-shift samples). The samples from matched controls were taken in parallel with workers before the shift. Leukocytes were isolated from heparinised blood on a Ficoll gradient. The enzyme-modified comet assay (DNA formamido-pyrimidine-glycosylase and endonuclease III) demonstrated a considerable increase of both single- and double-strand breaks in DNA (DNA-SB) and oxidised bases when compared with the controls (2.4× and 2×, respectively). Acute exposure induced a further increase of DNA-SB. The welding and smelting of nanocomposites represented a higher genotoxic risk than milling and grinding of nanocomposite surfaces. Obesity appeared to be a factor contributing to an increased risk of oxidative damage to DNA. The data also indicated a higher susceptibility of males vs. females to NP exposure. The study was repeated in September 2017. The results exhibited similar trend, but the levels of DNA damage in the exposed subjects were lower compared to previous year. This was probably associated with lower exposure to NP in consequence of changes in nanomaterial composition and working operations. The further study involving also monitoring of personal exposures to NP is necessary to identify (i) the main aerosol components responsible for genotoxic effects in workers handling nanocomposites and (ii) the primary cause of gender differences in response to NP action.

scholarly journals Efficiency of cleaning dental structural polymer materials and their resistance to biofouling

2020 ◽  
Vol 24 (4) ◽  
pp. 206-210
Author(s):  
F. A. Khafizova ◽  
R. M. Mirgazizov ◽  
I. R. Khafizov ◽  
Y. A. Ulyanov
Keyword(s):  
Mechanical Treatment ◽  
Microbial Contamination ◽  
Dental Materials ◽  
Polymer Materials ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
The Difference ◽  
Structural Polymer ◽  
Mechanical Cleaning

Aim. The formation of biofilms, involving microorganisms from the oral cavity, on the surface of various structural dental materials was investigated. Flexistron Plus, Dentalos Plus, and PEEK are used in dental orthopedic practice for prosthetics. Materials and methods. The difference in quantity depends on the structure and type of plastics, as well as on their mechanical cleaning. All the plastic samples were obtained using atomic force microscopy, which made it possible to detect differences in the microstructure and microrelief of all the types of plastics and to demonstrate bacterial growth on plastics before and after the mechanical cleaning of their surfaces with a toothbrush. Conclusion. The revealed facts of increased microbial contamination after the mechanical treatment of the surface of polymer materials suggest the need for additional lining with harder materials or the creation of new composites based on these polymers with high hygienic adequacy.

scholarly journals A Study on the Application of Laser Cleaning on the Weld of the Gas Fuel Supply Pipe for DF Engine

2021 ◽  
Vol 11 (24) ◽  
pp. 11832
Author(s):  
Ji-Eon Kim ◽  
Pyung-Su Kim ◽  
Jong-Myoung Lee ◽  
Han-Seop Choe ◽  
Jong-Do Kim
Keyword(s):  
Environmental Pollution ◽  
Work Environment ◽  
Process Parameters ◽  
Welding Process ◽  
Laser Cleaning ◽  
Chemical Cleaning ◽  
Fuel Supply ◽  
Before And After ◽  
Gas Fuel ◽  
Cleaning Technology

While producing gas fuel supply pipes for duel fuel (DF) engines, a welding process is essential. Accordingly, specimen management before and after welding is crucial to obtain highly reliable weldments. In this study, we developed an environmentally friendly laser cleaning technology to address a toxic work environment and environmental pollution problems caused by chemical cleaning technology utilized in post-welding treatment of gas fuel supply for DF engines. An experiment was conducted by implementing surface laser cleaning of the butt and fillet weldment specimens according to process parameters. Conditions of process parameters were identified for facilitating laser cleaning and used in prototype production. The prototypes were processed through laser and chemical cleaning, and the quality of the end products was compared. The results indicated that the proposed method satisfactorily cleans the prototype surface without generating a toxic work environment and environmental pollution problems. Moreover, the roughness of approximately 5 μm was achieved on the laser cleaned surface. This is considered to be able to increase the adhesion of the paint compared to the smooth chemical cleaned surface during the painting for anticorrosion of the product.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Changes in Platelet Aggregability after Ovariectomy

1979 ◽  
Vol 42 (04) ◽  
pp. 1332-1339 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Takeshi Motomiya ◽  
Minoru Sonoda ◽  
Noboru Miyagawa
Keyword(s):  
Platelet Count ◽  
Platelet Activation ◽  
Ovarian Hormones ◽  
Control Group ◽  
Platelet Aggregability ◽  
Appearance Rate ◽  
Before And After ◽  
The Difference ◽  
Induced Aggregation ◽  
Observation Period

SummaryChanges in platelets in 48 patients with uterine myoma before and after hysterectomy with and without ovariectomy were examined. Bilateral ovariectomy in 25 cases (ovariec-tomized group) and unilateral or non-ovariectomy in 23 cases (control group) were performed at the hysterectomy. Platelet count and an appearance rate of secondary aggregation decreased at one day after and increased at one week after the operation, similarly in both the ovariectomized and the control group. The appearance rate of secondary aggregation was reflected in an intensity of aggregation at 5 min after the addition of reagent to PRP. At one month after the operation, the appearance rate of secondary aggregation induced by 3 μM ADP showed a statistically significant decrease in comparison with the preoperation value (P <0.05) and the enhancement of 5-min aggregation was still observed in the control group, while ceased in the ovariectomized group. The difference between the two groups was significant (P < 0.05). There was almost no change in the speed and intensity of primary and secondary aggregation during the observation period. No significant differences in collagen-induced aggregation were noted between the two groups. The results suggest that ovarian hormones, mainly estrogen, facilitate platelet activation which is mediated by the so-called secondary aggregation.

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