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At least 1,009 records · Page 56Linked to original sources

PubMed2007

Monitoring imaging of lesions induced by high intensity focused ultrasound based on differential ultrasonic attenuation and integrated backscatter estimation.

We investigated the feasibility of two monitoring imaging methods to visualize and evaluate the high intensity focused ultrasound (HIFU) induced lesions in vitro during and after their formation, which were based on differential ultrasonic parameter estimation. Firstly, ultrasonic attenuation slope of tissue sample was estimated based on the spectral analysis of ultrasound RF backscattered signals. The differential attenuation slope maps were acquired, which were interpreted as the differences between the pretreatment image and those obtained in different stages during HIFU therapy. Secondly, ultrasonic integrated backscatter (IBS), defined as the frequency average of the backscatter transfer function over the useful bandwidth, was proposed quantitatively to evaluate the extent of lesions with the same RF signals as the first method. Differential IBS maps were also acquired to visualize temporal evolution of lesion formation. It was found in pig liver in vitro that more precise definition of the treated area was obtained from the differential IBS images than from differential attenuation slope images. Dramatic increase in both attenuation and IBS value was observed during the therapy, which may be related to dramatic enhancement of cavitation due to boiling and accompanying tissue damage. Two methods to obtain one differential image were compared and the cumulative differential image was found to be able to eliminate noises and artifacts to some extent, which was the cumulation of a series of differential images acquired from the differences between the temporally adjacent RF data frames. Moreover, we presented a bidirectional color code for identification of the artifacts due to tissue movements caused by HIFU radiation force. We conclude that cumulative differential IBS images have the potential to monitor the formation of HIFU-induced lesions.

Algorithms↗

PubMed2005

Synthesis of amorphous carbon nanoparticles and carbon encapsulated metal nanoparticles in liquid benzene by an electric plasma discharge in ultrasonic cavitation field.

A newly-developed method permits an electric plasma discharge to occur with relatively low electric power in insulating organic solutions due to the presence of an ultrasonic cavitation. A stable electric plasma could be generated in an ultrasonic cavitation field containing a thousand tiny activated bubbles, in which the electric conductivity could be improved due to formed radicals and free electrons, using copper electrodes and a titanium ultrasonic horn. This method allowed us to synthesize pyrolytic amorphous carbon nanoparticles smaller than about 30 nm in diameter from benzene liquid. In addition, we synthesized TiC nanoparticles about 50-150 nm in size, and copper nanoparticles smaller than 10 nm, which were encapsulated in multilayered graphite cages. Finally, we used GC-MS and MALDI-TOF-MS to observe and analyze the polymerized compounds and the degree of polymerization of the benzene liquid after the plasma treatment.

Benzene↗

PubMed2005

The effect of ultrasonic waves in conducting polymer solution.

The effects of ultrasonic wave on the conducting polymer polyaniline dissolved in DMSO were observed. The UV-visible, infrared and NMR analysis show that the polymer undergo a redox and doping transition when the ultrasound wave interacts with the polymer dissolved into the solvent. The proposed mechanism to explain these effects is based on the solvent's hygroscopicity properties. The interaction with the ultrasonic wave, homolitically dissociates the water molecule producing radical species, and these species interact with the dissolved conducting polymer changing its oxidation and doped state. The resulting effects of that interaction are the modification of oxidation state of the conducting polymer and the decrease of the amount of water molecule in the solvent. From those results, we have proposed one straightforward method to eliminate water contamination in the solvent DMSO using ultrasonic waves.

Aniline Compounds↗

PubMed2006

Ultrasonic damages on cyanobacterial photosynthesis.

Excessive cyanobacterial growth in eutrophic water sources has been a serious environmental problem, and both sight preservation and drinking water production demand control of cyanobacterial growth in water. Ultrasonic treatment was reported to effectively inhibit cyanobacterial growth through vesicle collapsing and cell fracturing, but little was known about the change of cyanobacterial photosynthesis during sonication. This paper examined the ultrasonic inhibition of Microcystis aeruginosa cell growth and extracellular microcystins release, and the instant ultrasonic decreases of antenna complexes like cyanobacterial chlorophyll a and phycocyanins (PC), and the oxygen evolution rate. The results showed that sonication effectively damaged antenna complexes, slowed down the photo-activity, which significantly inhibited the cell growth and microcystins formation and release.

Cell Proliferation↗

PubMed2006

Ultrasonic control of ceramic membrane fouling: Effect of particle characteristics.

In this study, the effect of particle characteristics on the ultrasonic control of membrane fouling was investigated. Ultrasound at 20 kHz was applied to a cross-flow filtration system with gamma-alumina membranes in the presence of colloidal silica particles. Experimental results indicated that particle concentration affected the ability of ultrasound to control membrane fouling, with less effective control of fouling at higher particle concentrations. Measurements of sound wave intensity and images of the cavitation region indicated that particles induced additional cavitation bubbles near the ultrasonic source, which resulted in less turbulence reaching the membrane surface and subsequently less effective control of fouling. When silica particles were modified to be hydrophobic, greater inducement of cavitation bubbles near the ultrasonic source occurred for a fixed concentration, also resulting in less effective control of fouling. Particle size influenced the cleaning ability of ultrasound, with better permeate recovery observed with larger particles. Particle size did not affect sound wave intensity, suggesting that the more effective control of fouling by large particles was due to greater lift and cross-flow drag forces on larger particles compared to smaller particles.

Equipment Failure↗

PubMed2001

Minimal invasive laparoscopic hysterectomy with ultrasonic scalpel.

BACKGROUND: The purpose of the study was to assess whether total laparoscopic hysterectomy with the ultrasonic scalpel offers advantages in term of intraoperative and postoperative outcomes over the conventional abdominal hysterectomy. METHODS: A case-control study to compare patients undergoing total laparoscopic hysterectomy and women undergoing abdominal hysterectomy for benign conditions was designed. Matching criteria were the menopausal status, the need of adnexectomy, and the uterus weight. The laparoscopic procedure was carried out using an ultrasonically activated scalpel and the amputated uterus was removed transvaginally. Every part of the operation was carried out via laparoscopy, from the adnexal phase to the colpotomy. Abdominal hysterectomy was performed using a conventional laparotomic technique. Intraoperative and postoperative characteristics were analyzed. RESULTS: One hundred forty-four patients were enrolled, of whom 48 underwent total laparoscopic hysterectomy and 98 abdominal hysterectomy. No difference was found between groups in terms of operating time or intraoperative and postoperative infectious and noninfectious complications. The median (range) total consumption of morphine (0 mg [0 to 16] versus 15 mg [0 to 100], P <0.01) during the first 3 postoperative days was significantly lower in the laparoscopic group than in the laparotomic group. The median (range) time to regular diet (1[0 to 4] versus 2 [0 to 5], P <0.05) and the time to passage of stool (1[1 to 2] versus 2 [1 to 5], P <0.05) was shorter in the laparoscopic than in the laparotomic group. CONCLUSIONS: Total laparoscopic hysterectomy with the ultrasonic scalpel is feasible and safe, and offers not only cosmetic benefits but also reduces the need of analgesia and the time to return to a normal gastrointestinal function in comparison with the conventional abdominal hysterectomy.

Case-Control Studies↗

PubMed2000

[Fundamental principles and pitfalls linked to the use of ultrasonic scissors].

In an ultrasonically activated device, electric energy is transformed to mechanical vibration, which is transmitted to the device's tip. By clamping the vessel between the tissue pad and vibrating blade, frictional heat is generated. This heat, significantly milder than that in electrocautery technique, is ideal for sealing the vessel. The ultrasonic vibration eventually divides the vessel. In the experimental studies, the cut end of medium-sized vessels divided by a scissor type ultrasonically activated device (USAD) withstood high intravascular pressure. However, our clinical experiences with the USADs suggest there are pitfalls including:--giving excessive tension to the vessel,--incomplete clamping of the vessel,--contacting the adjacent vessel with the back side of the active blade tip,--contacting the adjacent vessel with the blade tip. Some devices are described to prevent these pitfalls.

Blood Vessels↗

PubMed2004

An experimental study of surgical ultrasonic angioplasty: its effect on atherosclerosis and normal arteries.

BACKGROUND: We have developed a new hand-held probe for surgically open ultrasonic angioplasty. Two experimental studies were conducted to determine the optimal power range for carrying out ultrasonic angioplasty. METHODS: The probe measured 2.5 mm in diameter and 5 cm in length. The amplitude was 210 microm at 100% power. One of the studies was designed to determine the power range that is effective for removal of atherosclerotic lesions. Human cadaveric arteries were used in the study. The other study was designed to investigate the long-term adverse effect on normal arteries. Canine arteries were used in this study. RESULTS: In the study using cadaveric arteries, the amplitude ranging from 90 to 110 microm was effective for soft atheroma, the range from 110 to 130 microm was effective for mild arteriosclerosis, and 150 microm was effective for calcified lesions. The other study of the long-term effect on canine normal arteries indicated that each incidence of stenosis and occlusion was 0% at amplitude ranging from 90 to 110 microm, 13% at 130 microm, and 25% at 150 microm. CONCLUSIONS: The surgically open ultrasonic angioplasty with a new hand-held probe was effective for various kinds of atherosclerotic lesions, whereas the angioplasty at high amplitude had a problem with the long-term effect on normal arteries.

Angioplasty↗

PubMed1992

Viscous cosolvent effect on the ultrasonic absorption of bovine serum albumin.

Protein-ligand binding and enzyme activity have been shown to be regulated by solvent viscosity, induced by the addition of viscous cosolvents. This was indirectly interpreted as an effect on protein dynamics. However, viscous cosolvents might affect dynamic, e.g., viscosity, as well as thermodynamic properties of the solution, e.g., activity of solution components. This work was undertaken to examine the effect of viscous cosolvent on the structural dynamics of proteins and its correlation with dynamic and thermodynamic solution properties. For this purpose we studied the effect of viscous cosolvent on the specific ultrasonic absorption, delta mu, of bovine serum albumin, at pH = 7.0 and at 21 degrees C, and frequency range of 3-4 MHz. Ultrasonic absorption (UA) directly probes protein dynamics related to energy dissipation processes. It was found that the addition of sucrose, glycerol, or ethylene glycol increased the BSA delta mu. This increase correlates well with the solvent viscosity, but not with the cosolvent mass concentration, activity of the solvent components, dielectric constant, or the hydration of charged groups. On the grounds of these results and previously reported findings, as well as theoretical considerations, we propose the following mechanism for the solvent viscosity effect on the protein structural fluctuations, reflected in the UA: increased solvent viscosity alters the frequency spectrum of the polypeptide chain movements; attenuating the fast (small amplitude) movements, and enhancing the slow (large amplitude) ones. This modulates the interaction strength between the polypeptide and water species that "lubricates" the chain's movements, leading to larger protein-volume fluctuation and higher ultrasonic absorption. This study demonstrates that solvent viscosity is a regulator of protein structural fluctuations.

Absorption↗

PubMed1981

Ultrasonic degradation of schizophyllan, an antitumor polysaccharide produced by Schizophyllum commune Fries.

Schizophyllan, a water-soluble beta-D-glucan elaborated by Schizophyllum commune Fries, was partially depolymerized by ultrasonic irradiation to a low-molecular-weight polysaccharide, designated "sonic-degraded schizophyllan". Both native and degraded polysaccharides exhibited essentially the same antitumor activities against Sarcoma-180 ascites. Both glucans are comprised solely of D-glucose residues and have a main chain of (1 leads to 3)-beta-D-glucopyranosyl residues, one out of three glucose residues being attached as single, (1 leads to 6)-beta-D-glucopyranosyl groups. Although both glucans have similar structural features, significant differences are observed in such physical properties as molecular weight and intrinsic viscosity. End-group analysis by using radioisotope-labeled glucans suggests that ultrasonic degradation occurs mainly by cleavage of glycosidic bonds of the main chain of schizophyllan. The molecular weights of the native and sonic-degraded schizophyllan were shown to be 75% of those of corresponding, original schizophyllan preparations, suggesting that there is no anomalous linkage sensitive to periodate oxidation, and ultrasonic irradiation may cause random hydrolysis of (1 leads to 3)-beta-D-glucosidic linkages in the main chain.

Animals↗

PubMed1997

Proximity injury by the ultrasonically activated scalpel during dissection.

The ultrasonically activated scalpel is a high-frequency oscillating instrument that is reported to have a decreased dispersion of energy to surrounding tissues during use. To determine if this effect is beneficial and safe to surrounding tissue, it was used on anesthetized adolescent swine to dissect the portal vein from the pancreas, the renal artery and vein from the renal hilum, the ureter from the retroperitoneum, the aorta from the inferior vena cava and the common bile duct from surrounding tissue. Three-second contact to intestine and nerve roots was also performed. Wedge biopsy specimens of liver and spleen were performed. Dissection technique used was as described by the company. Structures were dissected with electrocautery using similar techniques for comparison. Tissues were harvested and placed in formalin for histological analysis. Dissection with the ultrasonically activated scalpel was simple, achieved excellent hemostasis, and did not appear to damage adjacent tissue. Microscopic analysis showed adventicial and media injury to vascular structures. The ureter and common bile duct demonstrated marked injury with regions of transmural coagulation. Nerve and small bowel did not appear to have much injury from the 3-second contact with the instrument. This study indicated that although the ultrasonically activated scalpel can ease dissection with good hemostasis, care must be taken to avoid injury to adjacent structures. Although its lateral energy dispersion may be less than that of cautery, it can still cause transmural necrosis to major structures.

Abdomen↗

PubMed1978

Effect of ultrasonic instrumentation on the retention of simulated cast crowns.

The effect of ultrasonic instrumentation on the retention of cemented cast restorations was studied. Forces required to dislodge castings from specimen assemblies subjected to ultrasonic vibrations did not differ significantly from those required to cause failure of noninstrumented specimens. The results indicate that clinical application of the ultrasonic device would not affect adversely the retention of properly cemented and well fitting cast restorations.

Crowns↗

PubMed1996

Surface roughness of tooth shoulder preparations created by rotary instrumentation, hand planing, and ultrasonic oscillation.

A dentinal shoulder with a smooth surface is necessary to ensure accurate adaptation of a porcelain crown. The surface roughness of dentinal shoulders prepared with different instruments was investigated in this in vitro study. Sixty shoulders, 1 mm wide, were prepared with coarse grit diamonds in extracted formalin-stored teeth. Of these 60 shoulders 20 were further refined with fine grit, and 20 more shoulders were refined with super-fine grit diamonds. The surface roughness (Ra) of the dentinal shoulders was recorded after each procedure. Thirty surfaces were further finished and refined with a hand chisel, and the other 30 surfaces were finished with a flat-ended diamond tip held in an ultrasonic generating device; the Ra was then recorded. These shoulder preparations were examined under a scanning electron microscope. The Ra of the dentinal shoulders prepared by the ends of the different grit diamonds was not significantly different (p > 0.05). Hand planing did not improve the Ra, and ultrasonic planing significantly increased the Ra (p < 0.05). Scanning electron micrographs revealed no apparent qualitative differences between surface roughness of the shoulders prepared by the diamonds or by the hand-planed surface. However, deeper scratches were evident at ultrasonically planed surfaces.

Crowns↗

PubMed1994

Experience with 17 cases of laparoscopic adrenalectomy: use of ultrasonic aspirator and argon beam coagulator.

Between January 17, 1992 and July 31, 1993, 11 patients with primary aldosteronism, 3 with Cushing's syndrome and 3 with a nonfunctioning adrenal tumor underwent laparoscopic adrenalectomy at our university hospital. In every patient adrenal tumor was removed successfully with adjacent normal adrenal tissue. The initial 10 operations were performed without use of an ultrasonic aspirator or argon beam coagulator, and the subsequent 7 procedures were done with those items. There was no difference between the groups in intraoperative blood loss or operative time. However, the tumors in the former group were significantly smaller than those of the latter group (mean 6.70 gm. versus 13.43 gm., respectively, p < 0.05, t test). For right tumors the argon beam coagulator was useful to resect or coagulate the liver, since adrenal tumors were sometimes tightly attached to the liver and upward retraction sometimes caused liver laceration. In obese patients or those with Cushing's syndrome the ultrasonic aspirator was useful to remove retroperitoneal fat surrounding the adrenal tumor without injury to the small vessels. The mean hospital stay for these 17 patients (11.63 days) was significantly shorter than that of 16 patients with corresponding adrenal tumors undergoing open removal during the last 5 years (17.32 days, p < 0.05 t test). In conclusion, laparoscopic adrenalectomy is feasible for the surgical treatment of primary aldosteronism, Cushing's syndrome and nonfunctioning adrenal tumors. The ultrasonic aspirator and argon beam coagulator may be useful for laparoscopic adrenalectomy.

Adrenal Gland Neoplasms↗

PubMed1983

Transurethral removal of large ureteral and renal pelvic calculi using ureteroscopic ultrasonic lithotripsy.

Transurethral ultrasonic fragmentation of stones allows successful endoscopic removal of upper urinary calculi that otherwise would be considered too large to extract. We successfully extracted endoscopically 2 large renal pelvic and 5 large ureteral stones using transurethral ureteropyeloscopy and ultrasonic lithotripsy. The stone is visualized first with the ureteropyeloscope, and then engaged in a basket and either fragmented or disintegrated with the ultrasonic transducer. Any remaining small stone fragments can be retrieved with a stone basket or forceps. There has been little morbidity with this procedure and patients can return to normal activity after discharge from the hospital.

Adult↗

PubMed1999

Social stress effects on territorial marking and ultrasonic vocalizations in mice.

Acute social defeat (SD) leads to transient and persistent physiological and behavioral changes. We examined the effects of acute SD on territorial urine marking and ultrasonic courtship vocalizations in DBA/2 male mice. Both behaviors are considered androgen dependent and are influenced by social status, with dominant mice displaying more of both behaviors. In Experiment 1, male mice that received SD displayed prolonged inhibition of territorial urine marking, relative to nondefeated control mice (NOSD). In addition, territorial marking increased with repeated tests. In Experiment 2, male mice that received 3 successive days of SD displayed fewer ultrasonic courtship vocalizations at 30 min. post-SD1 and 30 min. post-SD2, relative to NOSD mice. In Experiment 2, we also observed decreased territorial marking 4 weeks post-SD. In sum, SD induced prolonged inhibition of territorial marking, but had only transient effects on ultrasonic courtship vocalizations, suggesting that different mechanisms may mediate the maintenance of these behaviors.

Aggression↗

PubMed2002

Ultrasonic method for the whole blood coagulation analysis.

The developed ultrasonic method is based on the experimentally established fact that the ultrasound velocity in a blood sample is changing in a specific way during the blood clotting process. For ultrasound velocity measurements pulse echo method was selected. Implementation of this approach has a few problems caused by small dimensions of the measurement cell. All elements of the cell contacting with the blood are made of biologically compatible materials. The length of Pd coated chamber is 5 mm, volume 0.2 ml. Data of measurements are stored and processed by PC. The ultrasound velocity in a sample is displayed as it changes in time during the experiment; the temperature is monitored as well. Application of the digital filtering allows to smooth the coagulation curve and reach the sensitivity up to +/-3 cm/s. The coagulation curves were obtained at frequency 5 MHz and they represent peculiar stages of blood clotting characterised by their duration and ultrasound velocity differences. Fine structure of ultrasonic velocity changes is registered from the very beginning of the clotting to lysis. Such experiments were carried out using blood samples taken from a few hundred volunteers. For dynamic calibration and periodic checking of the measuring system the liquid medium in which acrylamide polymerisation reaction takes place is proposed as a reference liquid. Such a liquid mimics clotting blood from the point of view of ultrasonic velocity changes.

Blood Coagulation↗

PubMed2003

A power ultrasonic technology for deliquoring.

Solid-liquid separation is a topic of permanent interest in many areas such as mineral recovery, food processing and sewage disposal. The adequate application of high-intensity ultrasonic fields may contribute to improve the efficiency of conventional deliquoring processes. Deliquoring refers to removal of liquid from a product without changing its phase. Different effects are involved in the application of high-intensity ultrasound for deliquoring, the most important of which are: the alternating acoustic stresses, the radiation pressure, the acoustic streaming, interface instabilities and cavitation. One of the main advantages of the ultrasonic energy in deliquoring processes is its ability to release the strongly bound moisture. This paper deals with the application of an ultrasonic procedure for deliquoring of slurries in which a high-intensity vibration, homogeneously distributed, is directly applied to the wet particulate material. The vibration travels through the solid-liquid medium and the rapid series of alternative compressions and rarefactions produce a kind of "sponge effect" which favours the migration of moisture through natural or acoustically created channels. The obtained results show that the new technique is very promising to assist filtration processes for solid-liquid separation of highly concentrated suspensions of fine particles.

Filtration↗