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At least 505 records · Page 28Linked to original sources
PubMed2006

Fiber-optic laser Doppler turbine tip clearance probe.

A laser Doppler based method for in situ single blade tip clearance measurements of turbomachines with high precision is presented for what we believe is the first time. The sensor is based on two superposed fanlike interference fringe systems generated by two laser wavelengths from a fiber-coupled, passive, and therefore compact measurement head employing diffractive optics. Tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm (833 Hz, 586 m/s tip speed) are reported. At these speeds the measured uncertainty of the tip position was less than 20 microm, a factor of 2 more accurate than that of capacitive probes. The sensor offers great potential for in situ and online high-precision tip clearance measurements of metallic and nonmetallic turbine blades.

Journal Article↗
PubMed1985

Evaluation of the effect on root surfaces of air turbine scalers and ultrasonic instrumentation.

Three air turbine scalers were compared to each other and to an ultrasonic instrument (CAVITRON) on medium and maximum power setting. The amount of remaining calculus, roughness and loss of tooth substance were estimated by means of well-defined index systems (RCI and RLTSI). The time required to clean the test surfaces--marked on proximal root surfaces of mandibular incisors--was also noted. Standardized scanning electron microscope (SEM) micrographs were independently "blind-scored" by three examiners, and total mean scores were calculated. The results revealed significant differences (P less than 0.001) between the instruments with respect to the amount of remaining calculus. There were also significant differences (P less than 0.05) between roughness and loss of tooth substance produced by CAVITRON at maximum power setting and that produced by the other instruments. No differences were found with regard to the time required to clean the test surface (until visually clean).

Dental High-Speed Equipment↗
PubMed2004

Epoxy-based production of wind turbine rotor blades: occupational contact allergies.

BACKGROUND: An industry producing rotor blades for wind turbines with an epoxy-based technology had experienced an increasing number of workers with dermatitis, among whom the frequency of occupational contact allergy (OCA) was suspected to be underestimated. OBJECTIVE: To investigate the frequency of OCA by patch-testing with a specially profiled occupational patch test series. METHODS: In a blinded study design, 603 workers were first interviewed and thereafter clinically examined. Based on a history of work-related skin disease, clinical findings of dermatitis, or both, 325 (53.9%) of the workers were patch-tested with an occupational patch test series and the European Standard patch test series. RESULTS: Of the 603 investigated workers, 10.9% had OCA and 5.6% had contact allergy to epoxy resin in the standard test series. Contact allergy to amine hardeners/catalysts was found in 4.1% of the workers. Among the workers with OCA, 48.5% reacted to work material other than epoxy resin in the European Standard patch test series. CONCLUSION: Approximately 50% of the workers with OCA would not have been detected if only the European Standard patch test series had been used.

Adolescent↗
PubMed1989

Comparison of rotational speeds and torque properties between air-bearing and ball-bearing air-turbine handpieces.

We examined the effects of air pressure on the free-running speed of air-bearing and torque-type ball-bearing air-turbine handpieces. The air pressure for the former should be kept at a certain high level to maintain the stable super-thin air-bearing film and to provide the quasi-constant speed of around 420,000 to 480,000 rpm. On the other hand, the air pressure for the latter could be adjusted to provide some varieties of speeds, ranging from about 150,000 to 320,000 rpm. Subsequently, to compare torque properties and cutting effectiveness between these two handpieces, weight-load cutting tests were conducted, using a glass-ceramic workpiece and a commercial diamond point. It was confirmed that the air-bearing handpiece had the lower torque power but exhibited better cutting effectiveness, compared with its counterpart.

Air Pressure↗
PubMedDate not supplied

[ATP-synthase--intracellular molecular turbine].

Literature data on molecular and functional organization of ATP synthase as turbine-like rotary motor are reviewed. These data now provide the first experimental evidence that ATP synthases from different sources are able to reversibly couple the proton-motive force (proton electrochemical potential) with the synthesis/hydrolysis of ATP by the mechanical rotation of the rotor component of enzyme relative to the its stator part.

Molecular Motor Proteins↗
PubMed1977

[Microbiological studies on mouth-ringing, cooling and turbine-spray waters].

Microbiological examinations of mouth-cleaning, cooling, and turbine spray waters from various types of dental units showed different degrees of water contamination. The detection of Pseudomonas aeruginosa, because of the classification of this organism as a "problem germ", indicates the necessity for a more critical analysis of water used in stomatology including the elimination of possible sources of contamination.

Bacillus↗
PubMed2004

[The usage of inferior turbinate mucosal flap for repairing cleft lip].

OBJECTIVE: To evaluate a technique for decreasing the tension of the nasal floor during the procedures of repairing complete clef lip. METHODS: With the designation of an inferior turbinate mucosal flap combined with an oral mucosal flap in the splitting side, the tension was effectively decreased and the nasal floor was closed easily. Eighteen patients was selected for the treatment with this technique since 2000. The follow-ups were 10 to 24 months. RESULTS: All of the patients showed wound healing well with the significant improvement in the donor site. CONCLUSION: The above mentioned technique may effectively decrease the tension and be used to close the nasal floor safely. It could also reduce the incidence of the complications.

Cleft Lip↗
PubMed1990

Dentists' hearing and exposure to high speed turbine dental drill noise.

Effect of high speed turbine dental drill noise (DDN) on dentists' hearing at present and during the era of noisier drills was investigated. Hearing of two generations of dentists, power spectral density (PSD) functions of DDN from various drills and the equivalent level (LAeq) of a modern dental operatory were studied. The LAeq was 65 dB with 1 and 50% probability distribution levels of 74 and 57 dB, respectively. DDN was tonal with the spectrum peak always above 6 kHz, containing within 128 Hz frequency band 28-85% of the total noise energy in the PSD function. A cartridge type ball bearing drill from early 1960's was found noisier than an air bearing drill or a modern sealed head ball bearing drill by 8.5 and 5 dB, respectively. Sound pressure levels of DDN ranged from 68 to 79 dBA, being within safe limits. The high values earlier reported for cartridge type or worn drills could not be verified. Hearing of dentists free from clear ear pathology was found good and very similar to the reference, representing a population with no exposure to noise. There was no difference in hearing of 46 dentists 33-42 years of age, examined in 1973 and among whom there had been exposure to early and noisier drill, as compared to hearing of 56 dentists of similar age and years in dentistry, examined in 1988 and who had only been exposed to quieter drills of the 1970's. Noise dose and audiometric measurements were in agreement and indicated that DDN is not and has never been a risk to dentists' hearing.

Adult↗
PubMed1990

[Bacterial contamination of the atmosphere in the dental surgery during preparation with turbine tools].

The aerosol formed during work with turbine tools has an undesirable impact on the environment of dental surgeries. It may cause atmospheric transmission of infection. Recent qualitative and quantitative evaluation of aerosols assumes theoretical knowledge of physical and chemical properties and transformation of the aerosol system. These findings which influenced the selection of methods of the author's more recent measurements are the subject of the submitted paper.

Aerosols↗
PubMed1990

[Bacterial contamination of the atmosphere of the dental surgery during preparation with turbin equipment. 2. Microbiological examination of water of stomatological sets].

Water forms a substantial part of aerosol particles formed during preparation with turbin equipment. The authors assessed therefore before aerobiological examination of the atmosphere of the dental surgery which will be the subject of part III whether the water used for cooling of dental sets is contanined by pathogenic bacteria. Microbiological examination of water specimens of the cooling system of four dental sets of two types revealed only the presence of Baccilus subtilis and Gram-negative rods. The results of aerobic cultivation of all 48 water specimens were identical. The authors did not find a difference between water samples at the beginning and at the end of working hours nor between specimens collected on different days. The measurements were made as part of a student contest and the results were presented at a student conference at the Faculty of General Medicine, Charles University Prague and in a nation-wide contest in Kosice.

Aerosols↗
PubMedDate not supplied

[Scanning electron microscopy evaluation of wear of turbine rotary instruments].

A wear test was conducted to evaluate carbide and diamond dental burs, in air turbines at 400,000 r.p.m., by using a dentine-enamel substrate. There is less variability within each bur type. All of the burs showed a decreased ability to make a standard cut with succeeding trials. Generally, a linear dulling rate was observed with a progressive reduction of cutting effectiveness, except for middle grain burs, that showed better characteristics among tested burs.

Dental High-Speed Equipment↗
PubMed1989

The value of electrocautery to the inferior turbinates in the treatment of chronic rhinitis.

A study involving 69 patients with chronic nonspecific rhinitis who did not benefit from medical treatment and were subjected to cautery to the inferior turbinate. Fifty-one (73.9%) benefited from the procedure with little or no complications. This procedure which is cheap and yet effective is advocated for developing countries where cost of equipment, technical difficulties and complications will influence the choice of surgical treatment by the practitioner.

Adolescent↗
PubMed1979

[Material found on the cleaned diamond turbine drilling heads after injury cases].

Grinding of the hard tissues of the teeth with diamond points and airotor led to bullet-like flying off of part of the instrument. The causes were investigated: Unsatisfactory fixation in the turbine head, deficient material in the rotating instrument, unnecessary notches in the shaft resulting in reduction of diameter, and finally the so far uncorrected radial vibration of the rotating instrument. All of these causes may result in plastic deformation or breakage of the points.

Dental High-Speed Equipment↗
PubMed1983

[Toxicodynamic properties of liquids used for cooling high-power turbines. I. Acute, subacute and chronic toxicity].

Oils IWiOL-3 and OMTI are used to cool the high-power turbines. Their toxicodynamic properties are little known, therefore the studies described herein have been undertaken. The studies did not reveal high acute toxicity, as A-DL50 was found to exceed 15 g/kg of body weight. The simultaneous measurements of cholinesterase activity demonstrated its clear decrease, The studies of subacute toxicity after Lim showed that OMTI after a year's exploitation is the most toxic fluid, as C-LD50 for this compound is 6,21 g/kg of body weight, whereas C-LD50 for the other oils is: 22.449 g/kg of body weight for IW i 02-3-n and 20.93 g/kg of body weight for IWiOL-3-e. Studies of chronic toxicity showed decreased cholinesterase activity and no significant changes in the measurements of certain biochemical and haematological. indices.

Acute Disease↗
PubMed1983

[Comparison of selected physiological indicators and vegetative system tests in a group of turbine assemblers in relation to age and duration of employment].

The examinations covered 37 men--turbine assemblers--at the Thermal--electric Power Station Plant in Lódź. The subjects were classified by age into three groups: 21--30 years, 21--40 years and over 40 years and--by employment, length: 1--10 years, 11--20 years and over 20 years. All subjects underwent tests of selected physiological indices and vegetative system tests. The obtained results were compared in groups by age and employment duration. Most differences between particular groups were found to be insignificant. Significant differences referred to the same indices and vegetative system tests in both groups compared and were similar. The examinations indicated that it's of no matter whether in the tests are compared depending on age or employment duration.

Adult↗
PubMed1995

Decontamination of dental equipment. A validation of three devices designed for cleaning, disinfecting, and lubricating of dental high-speed turbines and handpieces.

This study deals with the decontamination of dental turbines and handpieces (DTH) aiming at eliminating the cross-infection risk in dental practice. Three types of equipment designed for cleaning/lubricating DTH were validated. The effect of the three devices was determined for four different types of DTH, which were artificially contaminated with Streptococcus salivarius ATCC 13419 in a controlled manner. Sampling was carried out by collecting one ml water flushed through the DTH connected to a dental unit. The study resulted in a model for testing the decontamination potential of a cleaning/lubrication device for DTH. One of the devices could not reduce the contamination, while two others were able to reduce the bioburden with at least 3.9 logarithmic steps. However none of the devices tested could constantly eliminate the contamination, for which reason an additional heat treatment of the DTH is recommended.

Alcohols↗
PubMed1976

[An experimental study of the effects of drilling with dental high speed turbine on culture cells (in vitro) (author's transl)].

A drilling at 500 000 R.P.M. with a dental high speed turbine was made either to a tissue culture bottle or to a test tube, in which mouse L fibroblasts were grown for 2 days with YLH medium supplemented with 10% bovine serum, in order to examine the effects of high speed drilling to the cells in vitro, Experiments were carried out with the following three conditions; (1) Drilling of outer surface of the glasswares at the inner surface on which the cells were attached, with a water coolant, (2) Drilling of the same place without a water coolant, and (3) Drilling of a remote area of the glasswares where no cells were grown. The last experimental condition permitted to give a sole effect of vibration accompanied with the drilling. Rates of cell multiplication and morphological observation were obtained on 2 days and 5 days after the glasswares were drilled. Rates of cell multiplication showed no change between the experimental conditions and control. This means that heat generation, vibration and/or their compound effects during drilling did not deter cells from growing. Morphological change of the cells due to the drilling was parallel to the results of cell multiplication except the drilling without a water coolant. When drilled without a water coolant, the cells around the drilled area was deteriorated and died after 24 hours. However, most of the cells away from the drilled area were not affected. The present results can not directly apply to the drilling in dental clinic, since in vivo condition has more complicated situation, some of which can not be simulated in in vitro environment. However, the in vitro results can surely be important information in resolving drilling effects in vivo.

Cell Division↗