SEARCH · PubMed Health

Results for “ULTRASONICS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources

PubMed2005

Ultrasonic degradation of oxalic acid in aqueous solutions.

This paper describes the ultrasonic degradation of oxalic acid. The effects of ultrasonic power, H(2)O(2), NaCl, external gases on the degradation of oxalic acid were investigated. Reactor flask containing oxalic acid was immersed in the ultrasonic bath with water as the coupling fluid. Representative samples withdrawn were analysed by volumetric titration. Degradation degree of oxalic acid increased with increasing ultrasonic power. It was observed that H(2)O(2) has negative contribution on the degradation of oxalic acid and there was an optimum concentration of NaCl for enhancing the degradation degree of oxalic acid. Although bubbling nitrogen gave higher degradation than that for bubbling air, both gases (for 20 min before sonication and during sonication together) could not help to enhance the degradation of oxalic acid when compared with the degradation without gas passage.

Air↗

PubMed1996

Ultraradical debulking of epithelial ovarian cancer with the ultrasonic surgical aspirator: a prospective randomized trial.

OBJECTIVE: Our purpose was to evaluate the effectiveness, benefits, and potential side effects of the use of the cavitational ultrasonic surgical aspirator for cytoreduction of advanced ovarian cancer. STUDY DESIGN: Forty patients with stage IIC to IV ovarian carcinoma were randomized to undergo ultraradical cytoreductive surgery with (group 1, 20 patients) or without (group 2, 20 patients) the use of the CUSA 200 cavitational ultrasonic surgical aspirator (Valleylab, Boulder, Colo). Preoperative and postoperative information and follow-up data were collected prospectively and compared between both groups. RESULTS: The amount of residual tumor after debulking surgery, the duration of the operation, and the rate of perioperative complications were comparable in both study groups. The amount of perioperative blood loss was significantly lower (1450 ml vs 1650 ml, p=0.02) in group 1. These patients had less morbidity (p<0.05), and could be discharged from the hospital significantly sooner (14 days vs 16 days, p=0.031). CA 125 levels 1 and 2 months after surgery were significantly lower in the group with cavitational ultrasonic surgical aspirator (p<0.01 and p<0.01, respectively), suggesting more successful cytoreduction. However, this is not reflected in a better disease-free or overall survival. CONCLUSION: Cavitational ultrasonic surgical aspirator-assisted cytoreductive surgery of advanced ovarian carcinoma is more effective in eradicating disease, reduces morbidity, and is cost beneficial.

Aged↗

PubMed2001

[Experimental study of monopolar electrical and ultrasonic dissection].

The aim of this experimental study was to compare the disadvantages of a monopolar electric scalpel and an ultrasonically-activated scalpel in a porcine model. Using thermal gradients, the ultrasonically-activated scalpel significantly decreased thermal energy dispersion to surrounding structures and thus decreased the risk of injuries to adjacent tissues and nerves, as opposed to the monopolar electric scalpel. Histological examination of nerves showed that necrosis was significantly less important with the use of the ultrasonically-activated scalpel. This experimental study demonstrated that the ultrasonically-activated scalpel caused less thermal and histological damage than the monopolar electric scalpel.

Animals↗

PubMed1985

Absolute measurement of enhanced fluctuations in assemblies of biomolecules by ultrasonic techniques.

By expressing the fluctuation-dissipation theorem explicitly, equations are obtained for the ultrasonic relaxation amplitudes that contain one single molecular parameter, i.e., the fluctuation, or the sum of fluctuations. The absolute measurement of this parameter is therefore possible. The equations apply to a two-state system, to a multistate system and to a linear Ising chain as well. In an aqueous medium, where molar volume changes are important, the ultrasonic relaxation amplitudes are proportional to the volume fluctuations. For assemblies of biomolecules that exhibit enhanced ultrasonic absorption on assembly it is possible to measure the increase on assembly of the sum of fluctuations. In view of application to tobacco mosaic virus protein aggregates, examples are given in which the fluctuations associated with two normal modes of relaxation are equally enhanced when the difference of conformational stability of the states is reduced. The corresponding observable changes of the ultrasonic spectra are described.

Macromolecular Substances↗

PubMed1994

Histopathological and adhesion formation after incision using ultrasonic vibrating scalpel and regular scalpel in the rat.

OBJECTIVE: To evaluate and to compare changes that occur in the uterine tissue of the rat after a standard incision with an ultrasonic vibrating scalpel and with a regular scalpel. SETTING: Sprague-Dawley white rats (Charles River Canada Inc., St. Constant, Quebec, Canada) in a conventional laboratory setting. INTERVENTIONS: A standardized incision was performed on the uterine horn with a regular scalpel on one uterine horn and with an ultrasonic scalpel on the opposite horn. MAIN OUTCOME MEASURES: Degree of adhesions and histopathological changes of the uterine horns. RESULTS: The degree of adhesion formation was similar, but the uterine horn distal to the incision was dilated in most uterine horns that were incised with ultrasonic scalpel. The degree of coagulation necrosis was significantly higher 7 and 14 days after incision with an ultrasound scalpel than after incision with a regular scalpel. CONCLUSION: The use of an ultrasonic vibrating scalpel is associated with more tissue injury than that of a regular scalpel, but it does not produce more adhesion formation.

Animals↗

PubMed2002

On-line purification of His-tag enhanced green fluorescent protein taken directly from a bioreactor by continuous ultrasonic homogenization coupled with immobilized metal affinity expanded bed adsorption.

In this report, we describe a new process for the on-line purification of His-tag EGFP (enhanced green fluorescent protein) taken directly from a bioreactor by continuous ultrasonic homogenization coupled with immobilized metal affinity expanded bed adsorption (IMAEBA). The use of proteins including a histidine-tag facilitates their subsequent purification after expression in many microorganisms. This meets the needs of scientific researchers as well as industrialists interested in purifying recombinant proteins. After evaluating the different flow-rates and ultrasonic probe sizes, the on-line purification was tested. After ultrasonic treatment, 70% of the cells were broken and 90% of free EGFP was recovered after IMAEBA. In our conditions, more than 450 mg of EGFP were obtained in 15 h. On-line bioreactor-ultrasonic probe-immobilized metal affinity expanded bed adsorption is a rapid automated technique for obtaining large quantities of pure EGFP.

Adsorption↗

PubMed2001

Performances estimation of a rotary traveling wave ultrasonic motor based on two-dimension analytical model.

The understanding of ultrasonic motor performances as a function of input parameters, such as the voltage amplitude, driving frequency, the preload on the rotor, is a key to many applications and control of ultrasonic motor. This paper presents performances estimation of the piezoelectric rotary traveling wave ultrasonic motor as a function of input voltage amplitude and driving frequency and preload. The Love equation is used to derive the traveling wave amplitude on the stator surface. With the contact model of the distributed spring-rigid body between the stator and rotor, a two-dimension analytical model of the rotary traveling wave ultrasonic motor is constructed. Then the performances of stead rotation speed and stall torque are deduced. With MATLAB computational language and iteration algorithm, we estimate the performances of rotation speed and stall torque versus input parameters respectively. The same experiments are completed with the optoelectronic tachometer and stand weight. Both estimation and experiment results reveal the pattern of performance variation as a function of its input parameters.

Algorithms↗

PubMed2001

Observations on changes in ultrasonically treated waste-activated sludge.

This work experimentally elucidates the effects of ultrasonic treatment on the physical, chemical, and biological characteristics of a waste-activated sludge. A critical ultrasonic power level exists above which, accompanied with the release of divalent cations from the sludge body, the floc structure effectively disintegrated, microbial level acceptably disinfected, and particulate organic compounds sufficiently transformed into soluble state. Both ultrasonic vibration and bulk temperature rise contribute to the treatment efficiency. Possible mechanisms of ultrasonic treatment are discussed.

Biodegradation, Environmental↗

PubMed1994

Evaluation of ultrasonic and sonic instruments for intraradicular post removal.

Ultrasonic instruments are a valuable asset for removing intraradicular posts from root canals before nonsurgical endodontic therapy. The purpose of this study was to evaluate the relative efficacy of post removal by ultrasonic and sonic devices. Fifty extracted teeth were instrumented and obturated. The canals were prepared and Parapost #5 posts were cemented with zinc phosphate cement. The teeth were divided into five groups, subjected to ultrasonic or sonic instrumentation and the time measured until post removal. Median values in minutes for the post extractions in each group were: Cavitron = 6.0, Enac = 8.3, and Neosonic = 41.2. Sonic instruments were generally unable to remove the posts. The results of this experiment indicate that the Cavitron and Enac ultrasonic units are significantly more efficient for removing posts than the Neosonic. Sonic instruments were not useful for post removal.

Cementation↗

PubMed1991

Histological evaluation of ultrasonic debridement comparing sodium hypochlorite and water.

Twenty extracted human mandibular first and second molars with mesial canal curvatures of 18 to 35 degrees were randomly divided into two groups. Following routine endodontic access and canal length determination one of the mesial root canals was ultrasonically instrumented, using tap water in the first group or 2.6% sodium hypochlorite irrigation in the other. In both groups the other mesial canal was used as a control. The mesial roots were decalcified, serially sectioned, and stained with hematoxylin and eosin. Wall planing and soft tissue debridement were blindly evaluated using the light microscope. Mean canal wall planing and soft tissue debridement scores were compared by multiple t tests. Sodium hypochlorite, in conjunction with ultrasonic instrumentation, was more effective than tap water in wall planing when the entire root length was considered. Sodium hypochlorite, in conjunction with ultrasonic instrumentation, was more effective than tap water in soft tissue debridement in the middle third of the canal. Both irrigants were ineffective in conjunction with ultrasonic instrumentation in removing soft tissue from the main canal, the isthmus between canals, the canal fins, and the multiple branches or deltas often encountered in the apical one-third of the canal.

Humans↗

PubMed1989

Stereomicroscopic evaluation of canal shape following hand, sonic, and ultrasonic instrumentation.

This study evaluated the root canal shape after using sonic, ultrasonic, and hand instrumentation on the mesial canals of extracted human mandibular first and second molars. One-hundred and five mesial roots were randomly divided into six experimental groups and one untreated control group of 15 roots each. The following instrumentation techniques were evaluated in the experimental groups: hand instrumentation with K-Flex files, sonic instrumentation with the Endostar 5, sonic instrumentation with the Sonic Air MM 3000, and ultrasonic instrumentation with the Cavi-Endo unit. Each technique was directly compared with each other. The mesial roots were instrumented alternating the techniques between the buccal and lingual canals in each group so that a direct comparison could be made. All canals were instrumented to a size corresponding to a #30 K-Flex file 1 mm from the anatomical apex. The roots were then sectioned perpendicular to the long axis so the apical and middle thirds could be evaluated with the stereomicroscope for canal shape. The control group was sectioned and examined without instrumentation. A significantly more regular shape was obtained at both levels with hand instrumentation than was obtained with either sonic or ultrasonic techniques. The comparisons between the sonic and ultrasonic techniques showed significantly better shapes were obtained with the Sonic Air MM 3000 instrument.

Dental Pulp Cavity↗

PubMed1989

The validity of using simulated root canals as models for ultrasonic instrumentation.

The validity of using simulated root canals in resin blocks for evaluating the effects of ultrasonic root canal instrumentation was examined. Curved canals in resin blocks and in natural teeth were ultrasonically instrumented using the Cavi-Endo unit at power setting 1. Canal shapes were compared qualitatively and quantitatively from photographs and subtraction macroradiographs of simulated canals and teeth, respectively. The following measurements were taken: apical and coronal areas, changes in width at the elbow and at 0.5 mm apical to the elbow, and apical transport width. Qualitatively, there did not appear to be any differences in the manner of removal of material along the length of the canal in both test models. Quantitatively, there was a similarity in the following: areas of canal walls removed, the incidence of elbows, the change in width at the region of the elbow, and the apical transport width. The lack of differences showed that the ultrasonic file cut in a similar fashion in both test models and indicated that simulated canals are valid models for evaluating the effects of ultrasonic instrumentation.

Dental Pulp Cavity↗

PubMed1996

Breakage of ultrasonic root-end preparation tips.

Modified ultrasonic tips are used to prepare rootend cavities during endodontic surgery. The purpose of this study was to determine whether such tips are prone to breakage during use. Ten different tip designs were driven by an ultrasonic unit at maximum power. Multirooted teeth were instrumented, the apex removed, and the tooth was placed horizontally on a pan balance. The apex was instrumented by each ultrasonic tip in turn for 15 min, with the load being increased by 100 g every 5 min. Those tips with curvatures of 70 degrees or greater fractured within the first 5-min loading period. Breakage occurred approximately 2 to 3 mm from the end and always at a bend. Scanning electron microscopy revealed that the fractures were brittle in nature, with little change in the remaining section. Two tips bent: one isthmus preparation tip and one silver point removal tip. All the other designs were deemed satisfactory after experimentation. This study shows that fracture of ultrasonic tips can occur and is related to the degree of bending.

Apicoectomy↗

PubMed1997

The effect of ultrasonics on sealer distribution and sealing of root canals.

The purpose of this study was to compare the ultrasonic and hand methods of sealer placement using three types of sealers: Sultan "Grossman's formula," AH-26, and CRCS. The effect of these methods on radiographic density, sealer distribution, and on the apical seal of the different sealers was evaluated. The in vitro experiment was carried out using human extracted mandibular incisors and mesio-buccal roots of maxillary first and second molars. Following standardized canal instrumentation, 120 single canal mandibular incisors were randomly assigned to six groups, depending on the type of sealer and method of sealer placement (hand versus ultrasonic). An additional ten teeth were used as controls. In the molar groups 40 canals were randomly assigned to two groups, with the method of sealer placement as the variable. Eight canals were used as controls. Postsealer analyses using radiographic density scores transformed to mm of sealer indicated that ultrasonics was superior to manual placement only for CRCS. Taken together, our investigation suggests that ultrasonics may enhance the placement of some sealers (i.e. CRCS) but not of others (i.e. AH-26 or Sultan). Method of sealer placement had no effect on apical leakage and therefore apparently on apical seal.

Analysis of Variance↗

PubMed1997

Comparison of dentinal crack incidence and of post removal time resulting from post removal by ultrasonic or mechanical force.

The purpose of this study was to compare the frequency of canal and intradentin cracks after intraradicular post removal using ultrasonic instrumentation or the Gonan post removal system. Sixty cadaver teeth were divided into 4 groups of 15 teeth each: group 1, ultrasonic removal; group 2, Gonan post removal system; group 3, cemented posts not removed; and group 4, no posts. Groups 1 and 2 were contralateral matched pairs. Para Posts were placed in groups 1, 2, and 3 to 7 mm apical to the cementoenamel junction and luted with ZnPO4 cement. The time required for post removal in groups 1 and 2 was recorded. The teeth were extracted, sectioned, and examined. Canal and intradentin cracks were mapped, and their frequency was recorded at each level. There were statistically more cracks present in the ultrasonic group than the no post group. There were no other differences that reached statistical significance. It took significantly longer for post removal using the ultrasonic tip versus the Gonan system.

Cadaver↗

PubMed1997

Evaluation for cracks associated with ultrasonic root-end preparation of gutta-percha filled canals.

Many clinicians use ultrasonics for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched human teeth for cracks before and after ultrasonic root-end preparation. Twenty matched pairs of extracted single rooted teeth were divided into two experimental groups. In group 1, root-end resection was performed on uninstrumented teeth. In group 2, root-end resection was performed after the canals were instrumented and filled with gutta-percha. All teeth in both groups received root-end preparations using ultrasonic instrumentation at low power. Two examiners evaluated the root-ends after root-end resection and again after root-end preparation using zoom magnification of 20x to 63x. The number, types, and location of cracks were mapped. There were no significant differences when gutta-percha filled roots were compared to uninstrumented roots with regard to the number or type of cracks after root-end resection or root-end preparation. In addition, there were no significant differences in the number or type of cracks following root resection and ultrasonic root-end preparation when compared to teeth with root resection alone.

Analysis of Variance↗

PubMed1998

The quality of ultrasonic root-end preparation: a quantitative study.

Ultrasonic root-end preparation techniques have recently been introduced and revolutionized the field of endodontic surgery. The purpose of this study was to compare quantitatively the quality of root-end preparation techniques prepared by a specially designed ultrasonic retrotip with those prepared in a traditional manner by a microhandpiece bur. Twenty roots with two canals and an isthmus from extracted maxillary human molars were selected for this study. After instrumentation, obturation, and root-end resection, root-end preparations were made using either an ultrasonic retrotip or a conventional microhandpiece bur. With the aid of the image processing and analysis system, the specimens were inspected under a stereomicroscope for further evaluation of the quality of the shape and size of preparation. The results of this investigation showed that the ultrasonic root-end preparations produced more conservative and less perforated cavities than those made with conventional microhandpiece bur preparations.

Evaluation Studies as Topic↗

PubMed2003

Monitoring the degradation process of biopolymers by ultrasonic longitudinal wave pulse-echo technique.

A non-destructive ultrasonic longitudinal wave pulse-echo technique was utilized to monitor the degradation process of three biodegradable polymers: poly(glycolic acid) (PGA), poly(L-lactic acid) (PLLA) and 50:50 poly(D,L-lactide-co-glycolide) (PDLLG). The degradation processes of PGA and PLLA, which have different molecular structure, were also studied by differential scanning calorimetry (DSC). The degradation processes of PDLLG specimens prepared by different methods were characterized by the ultrasonic wave technique and gel permeation chromatography (GPC). The resulting acoustic and thermal properties indicate that PLLA and PGA exhibit distinctly different degradation behavior, whereas the acoustic properties and molecular weight of PDLLG are sensitive with preparation methods. The present study demonstrates that ultrasonic wave technique provides a powerful tool in detecting the property changes of biodegradable polymers prepared with different manufacturing process and that the degradation behavior of biodegradable polymers can be closely monitored by ultrasonic technique.

Acoustics↗