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PubMed1982

Nasal turbinate atrophy in young mice inoculated with Bordetella bronchiseptica of pig origin.

Development of a model in experimental small animals will facilitate research on the mechanisms of nasal turbinate atrophy of swine. Atrophy of the nasal turbinate with Bordetella bronchiseptica phase I organisms of pig origin was induced by intranasal inoculation in 5-day-old or younger mice. Inoculations of phase I organisms into 10-day-old or older mice and of avirulent phase III organisms into 5-day-old or younger mice did not induce lesions of the disease, however. The lesions appeared in 40% of the susceptible-age mice which were examined at 2 weeks after inoculation and were present in 80% of the susceptible-age mice by 3 weeks. The lesions observed in young mice were similar to those reported for swine.

Animals↗
PubMed1993

Plasma endothelin-1 concentration in the inferior turbinate.

Endothelin (ET)-1 has the most potent vasocontrictive action of any substance known to date. Three milliliters of blood was removed from both the inferior turbinate and from the antecubital vein of six patients who underwent nasal surgery under general anesthesia. After centrifugation of the blood samples, the plasma was sent for radioimmunoassay of the plasma levels of ET-1. The plasma ET-1 level in the nasal blood vasculature was 6.4 +/- 1.0 pg/mL (mean +/- SEM), which was almost equivalent to that found in the antecubital vein (5.3 - 2.7 pg/mL) (N = 6). These values were greater than the normal range (1.5 +/- 0.5 pg/mL) probably because of the effect of general anesthesia. These results indicate that ET-1 is present in similar levels in the blood vessels of the inferior turbinate and the antecubital vein. A hypothesis that adrenaline induces ET production was not confirmed because topically applied adrenaline did not raise the plasma ET-1 level either in the nasal vasculature or in the peripheral vein.

Adult↗
PubMed1996

[Presumed physiopathology of the nasal wall surgery and contemporary techniques of the inferior turbinates surgery].

The lateral wall of the nasal cavity is anatomically complex and covers several nasal functions: ventilation, conditioning of the air, protection. This region also plays a prime role in maintaining nasal-sinus homeostasis through dynamic regulation of the two-way exchange between the nasal cavity and paranasal sinuses. In light of the most recently acquired information, physio-pathological aspect of the lateral wall are discussed in terms of ventilation mechanisms and mucociliary clearance of the paranasal sinuses. In this light, the key to nasal-sinus physiology is clearly the perviousness of the side wall ostium and, above all, the status of the structures making up the "ostiomeatal complex". The anatomo-functional integrity of the lateral wall is fundamental for sinus ventilation 90% of which depends on passive diffusion of air through ostium. It is also a key to mucociliary clearance, always directed toward the main ostium. This rationale provides the basis for the so-called functional surgery of the lateral wall aimed at restoring ostium permeability. One structure in the lateral wall is a key to nasal physiology: the lower turbinate. Anatomical or functional alterations of the lower turbinate is one of the major causes of nasal stenosis. Pharmacological treatment of this pathologies is not always satisfactory, hence one leans toward surgical treatments. Nevertheless, the wide range of techniques available attests to the fact that there is still great deal of uncertainty in this regard. After having analysed the data available in the literature, the authors propose a comparison of some of the most frequently used forms of surgery: electrocauterization, cryotherapy, laser therapy, submucosal decongestion with or without luxation, turbinectomy. Follow-up based on rhinomanometric evaluation, rhinometry, TTMC, IgA assay and symptom scoring has been performed for 4 years. The results show that the submucosal decongestion technique, particularly the variation with lateral luxation, is considered most effective in resolving obstruction while respecting nasal physiology.

Humans↗
PubMed1998

Inferior turbinate reduction surgery in children.

We assessed the effectiveness and safety of surgical reduction of the inferior turbinate in 64 children, ages three to 15 years, who were operated on between January 1985 and November 1995. All patients/parents were interviewed and assessed by means of a questionnaire one to 10 years postoperatively. All patients had follow-up and were evaluated clinically at one and two weeks postoperatively. Long-term follow-up visits occurred at six, 12 and 24 months. Eighty-nine percent of the children/parents reported a sustained improvement in their nasal airways. No cases of serious postoperative hemorrhage, excessive dryness nor long-term crusting of the nose were observed or reported. We conclude that in the treatment of children with severe nasal obstruction, surgical reduction of the inferior turbinate is a safe and effective operation, alone or in combination with other airway procedures, and may increase the effectiveness of subsequent medical management.

Adolescent↗
PubMed1998

The holmium:YAG laser for treatment of inferior turbinate hypertrophy.

Chronic hypertrophic rhinitis is sometimes refractory to local, as well as general, medical treatment. Before undertaking surgical reduction of the inferior turbinates, there is indisputably a place for cauterization or laser vaporization of the inferior turbinate mucosa. The authors present a study of 46 patients treated by the holmium:YAG laser for chronic hypertrophic rhinitis. The results after only one laser session are satisfactory in 89.1% at 6 months' follow-up and in 52.2% with mean follow-up of 16.2 months. No major secondary effects were observed.

Adolescent↗
PubMedDate not supplied

[Pneumatization of the middle nasal turbinate: a CT study].

Anatomic variations of the middle turbinate may be an important factor in the pathogenesis of inflammatory processes of the paranasal sinuses. A detailed analysis of coronal and axial plane CT scans of the paranasal sinuses obtained from 120 patients was performed. Paradoxical curve of the middle concha was detected in 24.2% of patients. Pneumatized middle turbinate was found in 42.5% and "true" concha bullosa in 8.3% of patients. Bilateral concha bullosa was found in 1.7% of patients.

Adolescent↗
PubMed2000

Cutting efficiency of air-turbine burs on cast titanium and dental casting alloys.

OBJECTIVE: The purpose of this study was to investigate the cutting efficiency of air-turbine burs on cast free-machining titanium alloy (DT2F) and to compare the results with those for cast commercially pure (CP) Ti, Ti-6Al-4V alloy, and dental casting alloys. METHODS: The cast metal (DT2F, CP Ti, Ti-6Al-4V, Type IV gold alloy and Co-Cr alloy) specimens were cut with air-turbine burs (carbide burs and diamond points) at air pressures of 138 or 207 kPa and a cutting force of 0.784 N. The cutting efficiency of each bur was evaluated as volume loss calculated from the weight loss cut for 5 s and the density of each metal. The bulk microhardness was measured to correlate the machinability and the hardness of each metal. RESULTS: The amounts of DT2F cut with the carbide burs were significantly (p < 0.05) greater than for the other titanium specimens at either 138 or 207 kPa. The diamond points exhibited similar machining efficiency among all metals except for Type IV gold alloy. The increase in the volume loss of Co-Cr alloy (Vitallium) cut with the diamond points showed a negative value (-29%) with an increase in air pressure from 138 to 207 kPa. There was a negative correlation between the amounts of metal removed (volume loss) and the hardness (r2 = 0.689) when the carbide burs were used. SIGNIFICANCE: The results of this study indicated that a free-machining titanium alloy (DT2F) exhibited better machinability compared to CP Ti and Ti-6Al-4V alloy when using carbide fissure burs. When machining cast CP Ti and its alloys, carbide fissure burs possessed a greater machining efficiency than the diamond points and are recommended for titanium dental prostheses.

Alloys↗
PubMed1999

Torque, power and efficiency characterization of dental air turbine handpieces.

OBJECTIVES: In a previous paper the flow and free running speed characteristics of dental air turbine handpieces were discussed. The present work was to continue the analysis and characterization of these handpieces by addressing the issues of torque, power generation, efficiency and the specification of figures of merit to aid comparative testing and selection. METHODS: Using the principle of the rope brake, torque was determined from stall to free running at a variety of supply pressures for fourteen models of handpiece. Using previous results for air flow rate and free running speed, power and efficiency were calculated. RESULTS: Stall torque was demonstrated to depend on rotor position. Dynamic torque was found to closely approach the expected linear relationship over the range from stall to free running. Several figures of merit (performance indices) were identified which might be used for routine rating and specification of handpieces. CONCLUSIONS: Standardized testing can now be performed and effective figures of merit derived to characterize the behaviour of dental air turbine handpieces.

Algorithms↗
PubMed1997

Chitosan as a nasal delivery system: the effect of chitosan solutions on in vitro and in vivo mucociliary transport rates in human turbinates and volunteers.

In these studies, we examined the effect on mucociliary transport rates (MTR) of various 0.25% (w/v) chitosan solutions applied to human nasal tissue both ex vivo and in vivo. In the first study a range of chitosans with different molecular weights were applied to freshly amputated human nasal turbinates, and their effect on MTR was recorded. The transient inhibitory effect on turbinate MTR that was found for most of the chitosan preparations showed a marked dependence on the volume of chitosan solution applied and the molecular weight of the chitosan tested. The higher the molecular weight of the chitosan and the more chitosan applied, the longer the original MTR was depressed. A small scale human trial, investigating the effect of chitosan glutamate, on saccharin clearance times, was also undertaken. The study showed that a once daily application of a 0.25% solution of the chitosan for 7 days had no effect on either saccharin clearance times or nasal histology as examined by light microscopy.

Adult↗
PubMed1997

A laboratory evaluation of two brands of disposable air turbine handpiece.

OBJECTIVE: To report on the essential performance characteristics of two brands of disposable air turbine handpiece and on aspects of their safety and convenience for clinical use. MATERIALS AND METHODS: Oralsafe and Feathertouch disposable handpieces were characterised using a variety of techniques in respect of the following: turbine rotor radius, equivalent orifice radius, stall torque coefficient, pressure effectiveness, power index, efficiency index, sound level and instrument retention force. RESULTS: Free-running speed versus pressure curves for many of the disposable handpieces showed marked deviations from the expected smooth form. Considerable variation between examples of each type was found in most measured values. Evidence of eccentric rotors and high bearing friction was not found. CONCLUSIONS: Both brands of disposable handpiece had a number of problems: poor performance, vibration, excessive noise, variability of behaviour, poor bearings. Use of these devices is difficult to recommend. Improvement in design seems necessary.

Air Pressure↗
PubMed2005

Impacts of biodiesel on pollutant emissions of a JP-8-fueled turbine engine.

The impacts of biodiesel on gaseous and particulate matter (PM) emissions of a JP-8-fueled T63 engine were investigated. Jet fuel was blended with the soybean oil-derived methyl ester biofuel at various concentrations and combusted in the turbine engine. The engine was operated at three power settings, namely ground idle, cruise, and takeoff power, to study the impact of the biodiesel at significantly different pressure and temperature conditions. Particulate emissions were characterized by measuring the particle number density (PND; particulate concentration), the particle size distribution, and the total particulate mass. PM samples were collected for offline analysis to obtain information about the effect of the biodiesel on the polycyclic aromatic hydrocarbon (PAH) content. In addition, temperature-programmed oxidation was performed on the collected soot samples to obtain information about the carbonaceous content (elemental or organic). Major and minor gaseous emissions were quantified using a total hydrocarbon analyzer, an oxygen analyzer, and a Fourier Transform IR analyzer. Test results showed the potential of biodiesel to reduce soot emissions in the jet-fueled turbine engine without negatively impacting the engine performance. These reductions, however, were observed only at the higher power settings with relatively high concentrations of biodiesel. Specifically, reductions of approximately 15% in the PND were observed at cruise and takeoff conditions with 20% biodiesel in the jet fuel. At the idle condition, slight increases in PND were observed; however, evidence shows this increase to be the result of condensed uncombusted biodiesel. Most of the gaseous emissions were unaffected under all of the conditions. The biodiesel was observed to have minimal effect on the formation of polycyclic aromatic hydrocarbons during this study. In addition to the combustion results, discussion of the physical and chemical characteristics of the blended fuels obtained using standard American Society for Testing and Materials (ASTM) fuel specifications methods are presented.

Air Pollution↗
PubMed1996

Repeatability of a rapid dosimetric method for methacholine challenge using a pocket turbine spirometer for FEV1 measurements.

The repeatability of a rapid dosimetric method for methacholine challenge was evaluated with 11 asthmatic patients. A Spira Elektro 2 dosimeter was used for methacholine delivery and a pocket turbine spirometer (Micro Spirometer) for FEV1 measurements. Methacholine was delivered in four successive, increasing doses ranging from 80 micrograms up to a cumulative dose of 6900 micrograms. The single determination standard deviation was low (12.5%), corresponding to a 95% confidence interval of +/- 0.925 doubling doses. The mean difference (+/- SE) between measurements of log PD20 FEV1 was -0.015 (0.056), and the absolute value of the difference in log PD20 FEV1 was not significantly related to the average log PD20 FEV1 (r = -0.155, P = 0.65). The rapid dosimetric methacholine challenge test, performed with a pocket turbine spirometer, proved to be as reproducible as previous methods. Furthermore, this methacholine challenge is clearly less time consuming than conventional provocations, including bronchodilator aerosol (given to resolve post-challenge bronchoconstriction); the whole test can be performed in 20 min. This is especially valuable in epidemiologic studies, as well as in clinical practice.

Administration, Inhalation↗
PubMed2001

Secondary flows in axial turbines--a review.

An important problem that arises in the design and the performance of axial flow turbines is the understanding, analysis, prediction and control of secondary flows. Sieverding has given a review of secondary flow literature, covering up to 1985. In this paper a brief review of pre-1985 work is given, and then a survey of open literature secondary flow investigations since the Sieverding review is presented. Most of the studies reviewed deal with plane or annular cascade flows. Tip clearance effects are not covered. The basic secondary flow picture for a turbine cascade, as measured and verified by a number of investigators is described. Recent work that shows refined secondary flow vortex structures is examined. A flow parameter based on inlet boundary layer properties used to predict horseshoe vortex swirl is presented. Work on secondary flow loss reduction, involving airfoil geometry, endwall fences and endwall contouring is briefly reviewed. A new leading edge bulb geometry that has demonstrated impressive loss reduction is considered. It is concluded that accurate routine prediction of secondary flow losses has not yet been achieved, and must await either a better turbulence model or more experiments to reveal new endwall loss production mechanisms. Lastly, loss is examined from the standpoint of entropy generation.

Journal Article↗
PubMed2001

Unsteady flow modelling in turbine stage.

The paper deals with the problems of unsteady flow modelling in turbine stage. The impact of unsteadiness in the design procedure as well as in the real flow phenomena are briefly addressed. After a discussion of the physical aspects of the real flow in turbine stage which differ from the unsteady flow in a single row environment, the paper reports a survey of the actual and more recent approaches to the numerical modelling on the unsteady flow in multiple rows environment. The classical steady models, used for long time in the design procedure, are addressed and their limits are focused. The more complex procedures ranging from quasi-unsteady methods to the fully unsteady methods are reported and investigated in details. The discussion on the specific features of the different approaches is pointed to assess the accuracy, the feasibility, the robustness and the usability (i.e. the computer time and storage requirements). Sample results from the author research activity are reported and presented. Discussion of crucial and open questions to improve the prediction capability of the methods are finally reported as well as some comments on the possibility to joint classical (steady methods) and advanced approaches (fully unsteady methods) to improve the actual design procedure are addressed.

Journal Article↗
PubMed2001

The detailed structure and behavior of discrete cooling jets in a turbine.

Three-dimensional jets are an efficient way of cooling the walls of modern high-pressure turbines. Introduced in the external flow that develops around the turbine blade, they are associated with a set of vortex structures. The purpose of this paper is to underline the respective origin and importance of these structures, with reference to both experimental and numerical results. Steady and unsteady vortices will be analyzed. Recommendations for numerical simulations will be proposed from these observations.

Journal Article↗
PubMed2001

Jet-impingement heat transfer in gas turbine systems.

A review of jet-impingement heat transfer in gas turbine systems is presented. Characteristics of the different flow regions for submerged jets--free jet, stagnation flow, and wall jet--are reviewed. Heat transfer characteristics of both single and multiple jets are discussed with consideration of the effects of important parameters relevant to gas turbine systems including curvature of surfaces, crossflow, angle of impact, and rotation.

Journal Article↗