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United States (U.S.) Navy sailors are exposed to a very large number of hazards, both chemical and physical. Occupational vibration from pneumatic air tools is one of the potential exposure hazards. There are very limited data as to the exposures to one type of tool, a needle gun or needle scaler, used by the sailors.The purpose of this study was to characterize the vibration levels generated by a needle gun used in the U.S. Navy. The design of the study evaluated the difference pressure had on the acceleration levels generated from the needle scaler. Five subjects were used in the evaluation of the tool. Each subject was required to hold the tool for twenty seconds activated without contact and activated on a surface and at two different pressures, 60 and 80 pound per square inch (psi). Each subject repeated each of the conditions three times for a total of 12 measurements. Each subject was also required to hold the tool in hand without the tool activated. The measurements were collected from an accelerometer on the needle gun following ISO 5349-1:2001 and ISO 5349-2:2001 methods. Significant differences were observed individually in pressure (p<0.0001), contact (p<0.0001)), and subjects (p<0.001). In addition, there was a significant interaction between contact and pressure (p<0.001). It was concluded that U.S. Navy sailors are not likely at significant risk to Hand-Arm Vibration Syndrome for lifetime exposures to hand transmitted vibration.

The aim of this work is to propose a cranktrain of a petrol six-cylinder aircraft engine with the specified parameters. Build dynamic model involved an air reducer and carry out the life-stress analysis important key parts of the crankshaft.

Objectives: Since ultrasonic dental scalers contain internal narrow-diameter waterline tubing susceptible to bacterial biofilm growth, this study determined the cultivable prevalence of aerobic mesophilic heterotrophic bacteria in ultrasonic scaler output water subjected to one of two commercial biocides favorably reviewed by the American Dental Association as effective for microbial biofilm control in dental unit waterlines, and assessed the potential antimicrobial effect on output water of an ultrasonic scaler tip activated at a maximum power frequency. Methods: Aseptically-collected water samples were obtained, and neutralized for residual chlorine with sodium thiosulfate, from 12 ultrasonic scalers provided municipal tap water treated with an iodine resin cartridge (Group A), and from eight ultrasonic scalers provided distilled water treated with a 0.78% silver ion-based disinfectant (Group B), all within a dental school clinic setting. The latter eight ultrasonic scalers were additionally sampled after output water was passed through an inserted scaler tip activated to a maximum power setting similar to its potential use in clinical patient care. All water samples were evaluated for aerobic mesophilic heterotrophic bacteria using nationally-accepted analytical procedures detailed in Standard Methods for the Examination of Water and Wastewater, 23rd Edition (2017), with sample aliquots spread-plated onto R2A agar and aerobically incubated at 28°C for seven days. Aerobic mesophilic heterotrophic bacteria were considered elevated when ≥ 500 CFU/ml of the species were recovered per water sample. Predominant cultivable isolates of aerobic mesophilic heterotrophic bacteria in the water samples were identified using matrix- assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry and Bruker MALDI Biotyper analytic software. Results: Aerobic mesophilic heterotrophic bacteria averaged 610 ± 380 (SD) CFU/ml per ultrasonic scaler in Group A ultrasonic scalers, with eight of 12 (66.7%) evaluated ultrasonic scalers yielding elevated counts ≥ 500 CFU/ml. Similar mean values of 667 ± 340 (SD) CFU/ml per ultrasonic scaler were found in Group B ultrasonic scalers, with five of eight (62.5%) evaluated ultrasonic scalers yielding elevated aerobic mesophilic heterotrophic bacteria counts ≥ 500 CFU/ml. Acidovorax temerans, Novosphingobium subterraneum, Cupriavidus metallidurans, and Sphingobium yanoikuyae were the most prevalent cultivable species identified from ultrasonic scaler waterlines where the source water was municipal tap water treated with molecular iodine. In contrast, nearly pure growth of Cupriavidus metallidurans alone dominated cultivable waterline isolates from ultrasonic scalers where the source water was distilled water treated with a 0.78% silver ion disinfectant. No statistically significant impact was found on aerobic mesophilic heterotrophic bacterial counts after ultrasonic scaler output water passed through an inserted scaler tip activated to maximum power (P &gt; 0.05, Wilcoxcon signed-rank test). Conclusions: Approximately two-thirds of ultrasonic scalers in a dental school clinic setting yielded output water that failed to meet potable water regulatory standards in the United States with regard to aerobic mesophilic heterotrophic bacterial counts, even when subjected to disinfection with one of two American Dental Association favorably-reviewed biocide products, or exposed to high-frequency ultrasonic scaler tip oscillations. These findings question the effectiveness of infection control procedures used to manage ultrasonic scaler waterlines, and raise concerns about the safety of ultrasonic scaler output water introduced into the oral cavity of dental patients during dental treatment procedures. / Oral Biology

Den till sjöss vanliga nålhackan som används vid rostskyddsarbete avger kraftigt stötande vibrationer som kan skada användaren efter extensiv användning. Syftet med denna studie var att klarlägga hur mycket vibrationer ett däcksmanskap kan utsätts för under en normal arbetsdag samt vilka hälsorisker som föreligger vid användning av nålhackan. Två metoder har använts för att genomföra studien. En fältstudie användes för att ta reda på vilka hand- och armvibrationsnivåer ett däcksmanskap kan komma upp i vid arbete med nålhacka. Detta skede via loggning av tid som nålhackan använts på fyra olika fartyg och resultatet ställdes sedan mot lagstadgade insats- och gränsvärden för hand- och armvibrationer. En litteraturundersökning användes för att komma fram till hur hand- och armvibrationer, HAV, påverkar arbetaren och vilka risker som föreligger vid HAV-exponering. Fältstudieresultatet visar att genomsnittsvärden överskred arbetsmiljölagens lagstadgade gränsvärden för hand- och armvibrationer. Resultatet från litteraturstudien tyder på att däcksmanskapsyrket skulle kunna vara en riskfaktor för utvecklande av hand- och armvibrationssyndrom, HAVS, som kan ge symtom såsom vita fingrar, försämrad finmotorik och greppstyrka. / At sea, the needle scaler is a commonly used tool for removing rust and preparing steel surfaces for new paint. Prolonged exposure to its strong vibrations can cause harm to the user. The purpose of this study was to determine the amount of vibration exposure a seaman working on deck with needle scalers can reach during a normal working day, and how this exposure can affect the worker’s health. To accomplish this, two methods were used. A field study was used, aimed to determine the daily vibration exposure, by logging the time needle scalers were used on board four different merchant ships. A literature search was used aimed at examining how hand- arm vibration, HAV, affect the worker and what risks HAV-exposure can generate. The result from the field study showed that the average vibration values ​​exceeded European statutory limits. The result from the literature study showed signs that the deck seaman profession may be a risk factor in developing hand- and arm vibration syndrome, HAVS, with symptoms such as impaired dexterity, white finger syndrome and reduced grip strength in the hand as possible risks.