Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 445
Filter
1.
Philos Trans A Math Phys Eng Sci ; 381(2249): 20220055, 2023 Jun 26.
Article in English | MEDLINE | ID: mdl-37150207

ABSTRACT

The Southern Ocean is a major sink of atmospheric CO2, but the nature and magnitude of its variability remains uncertain and debated. Estimates based on observations suggest substantial variability that is not reproduced by process-based ocean models, with increasingly divergent estimates over the past decade. We examine potential constraints on the nature and magnitude of climate-driven variability of the Southern Ocean CO2 sink from observation-based air-sea O2 fluxes. On interannual time scales, the variability in the air-sea fluxes of CO2 and O2 estimated from observations is consistent across the two species and positively correlated with the variability simulated by ocean models. Our analysis suggests that variations in ocean ventilation related to the Southern Annular Mode are responsible for this interannual variability. On decadal time scales, the existence of significant variability in the air-sea CO2 flux estimated from observations also tends to be supported by observation-based estimates of O2 flux variability. However, the large decadal variability in air-sea CO2 flux is absent from ocean models. Our analysis suggests that issues in representing the balance between the thermal and non-thermal components of the CO2 sink and/or insufficient variability in mode water formation might contribute to the lack of decadal variability in the current generation of ocean models. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.

2.
J Visc Surg ; 159(4): 267-272, 2022 08.
Article in English | MEDLINE | ID: mdl-34303637

ABSTRACT

AIM: Lateral internal sphincterotomy (LIS) remains a standard for chronic anal fissure even though other surgical techniques have shown high efficacy. Faecal incontinence is a well-documented complication of LIS. We devised modified open posterior internal sphincterotomy (m-OPIS) with sliding skin graft (SSG), which is a combined procedure of OPIS and anal advancement flap. The aim of this study is to evaluate m-OPIS+SSG. METHODS: This was a retrospective, observational, single-arm study. m-OPIS+SSG was performed for chronic anal fissure and anal stenosis. m-OPIS involved incision of the internal sphincter muscle at the posterior midline until four fingers could be passed. The incision wound was closed by anastomosis of the anoderm and skin. Then, an arcuate skin incision was created and the skin graft was advanced into the anal canal. Follow-up was conducted by clinical consultation and telephone interview. Faecal continence was assessed by Cleveland Clinic Faecal Incontinence (CCFI) score. RESULTS: m-OPIS+SSG was performed in 143 patients. The mean patient age was 50±16 years. The success and overall recurrence rates after m-OPIS+SSG were 99% and 0.7%, respectively, with a median follow-up period of 16.3 years. One patient developed incontinence with liquid stools once during the 6-month period. None of the other patients suffered permanent faecal incontinence postoperatively. The postoperative CCFI score was 0.5±0.9. CONCLUSIONS: We consider m-OPIS+SSG as one of the efficacious options of procedure for chronic anal fissure and anal stenosis, owing to its high success rate, low recurrence rate and no postoperative complication of serious faecal incontinence.


Subject(s)
Fecal Incontinence , Fissure in Ano , Lateral Internal Sphincterotomy , Adult , Aged , Anal Canal/surgery , Chronic Disease , Constriction, Pathologic/etiology , Constriction, Pathologic/surgery , Fecal Incontinence/etiology , Fecal Incontinence/surgery , Fissure in Ano/complications , Fissure in Ano/surgery , Humans , Lateral Internal Sphincterotomy/adverse effects , Middle Aged , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Postoperative Complications/surgery , Skin Transplantation/adverse effects , Treatment Outcome
3.
Colorectal Dis ; 21(5): 588-594, 2019 05.
Article in English | MEDLINE | ID: mdl-30673147

ABSTRACT

AIM: Rectal prolapse (RP) is usually associated with elderly women and is well recognized as having a detrimental effect on quality of life. A number of surgical procedures for RP are available, but morbidity and mortality are substantial. The Gant-Miwa-Thiersch procedure (GMT) has been frequently used for RP in Japan. However, as GMT has a high recurrence rate it is not widely used elsewhere. The aim of this study was to evaluate a modified version of GMT (mGMT) in comparison with other procedures. METHOD: mGMT was performed under spinal or local anaesthesia in 187 patients with RP. No normal mucosa was left between the tags and lateral wounds were created in the Thiersch procedure. Morbidity, mortality and recurrence rates were recorded. RESULTS: No serious postoperative complications and no operative deaths occurred after mGMT. Eight per cent of patients suffered from infection of the strings. The overall recurrence rate after mGMT was 7.5% with a median follow-up period of 13.8 years. CONCLUSION: On the basis of these results, we consider that mGMT has a number of advantages: it is minimally invasive, does not require general anaesthesia, is technically simple to perform and is associated with satisfactory outcomes and low morbidity. mGMT should be considered an option for the treatment of RP in elderly patients.


Subject(s)
Anal Canal/surgery , Digestive System Surgical Procedures/methods , Intestinal Mucosa/surgery , Rectal Prolapse/surgery , Rectum/surgery , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Rectal Prolapse/etiology , Recurrence , Treatment Outcome
4.
Nat Commun ; 7: 10903, 2016 Mar 29.
Article in English | MEDLINE | ID: mdl-27020134

ABSTRACT

The magnetic field-induced changes in the conductivity of metals are the subject of intense interest, both for revealing new phenomena and as a valuable tool for determining their Fermi surface. Here we report a hitherto unobserved magnetoresistive effect in ultra-clean layered metals, namely a negative longitudinal magnetoresistance that is capable of overcoming their very pronounced orbital one. This effect is correlated with the interlayer coupling disappearing for fields applied along the so-called Yamaji angles where the interlayer coupling vanishes. Therefore, it is intrinsically associated with the Fermi points in the field-induced quasi-one-dimensional electronic dispersion, implying that it results from the axial anomaly among these Fermi points. In its original formulation, the anomaly is predicted to violate separate number conservation laws for left- and right-handed chiral (for example, Weyl) fermions. Its observation in PdCoO2, PtCoO2 and Sr2RuO4 suggests that the anomaly affects the transport of clean conductors, in particular near the quantum limit.

5.
Gene Ther ; 18(4): 384-93, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21085194

ABSTRACT

Human artificial chromosomes (HACs) have several advantages as gene therapy vectors, including stable episomal maintenance, and the ability to carry large gene inserts. We previously developed HAC vectors from the normal human chromosomes using a chromosome engineering technique. However, endogenous genes were remained in these HACs, limiting their therapeutic applications. In this study, we refined a HAC vector without endogenous genes from human chromosome 21 in homologous recombination-proficient chicken DT40 cells. The HAC was physically characterized using a transformation-associated recombination (TAR) cloning strategy followed by sequencing of TAR-bacterial artificial chromosome clones. No endogenous genes were remained in the HAC. We demonstrated that any desired gene can be cloned into the HAC using the Cre-loxP system in Chinese hamster ovary cells, or a homologous recombination system in DT40 cells. The HAC can be efficiently transferred to other type of cells including mouse ES cells via microcell-mediated chromosome transfer. The transferred HAC was stably maintained in vitro and in vivo. Furthermore, tumor cells containing a HAC carrying the suicide gene, herpes simplex virus thymidine kinase (HSV-TK), were selectively killed by ganciclovir in vitro and in vivo. Thus, this novel HAC vector may be useful not only for gene and cell therapy, but also for animal transgenesis.


Subject(s)
Chromosomes, Artificial, Human , Genetic Therapy/methods , Genetic Vectors , Animals , Cell Line , Chromosomes, Human, Pair 21 , Cloning, Molecular , Gene Transfer Techniques , Humans , Mice , Recombination, Genetic
6.
Rev Sci Instrum ; 81(10): 10E511, 2010 Oct.
Article in English | MEDLINE | ID: mdl-21034039

ABSTRACT

The He I optical emission spectroscopy that considers the spatial structure of radiation trapping was proposed by us and was applied to a MAP-II divertor simulator. The spatial distribution of the optical escape factor was calculated from the n (1)P (n≥3) state profiles measured by visible spectroscopy. The profile of 2 (1)P, which is immeasurable by visible spectroscopy, needs to be broader than that of the 3 (1)P state. The sensitivity of the 2 (1)P profile to the T(e) value estimated by He I spectroscopy is investigated.

7.
Br J Pharmacol ; 159(6): 1201-10, 2010 Mar.
Article in English | MEDLINE | ID: mdl-20136830

ABSTRACT

BACKGROUND AND PURPOSE: Much interest is currently being focused on the anti-nociceptive effects mediated by nicotinic acetylcholine (nACh) receptors, including their location and mechanism of action. The purpose of this study was to elucidate these issues using 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5IA), a nACh receptor agonist, and [(125)I]5IA. EXPERIMENTAL APPROACH: We partially ligated the sciatic nerve of Sprague-Dawley rat to induce neuropathic pain [Seltzer's partial sciatic nerve ligation (PSL) model]. We then examined the changes in nACh receptor density in the CNS using [(125)I]5IA autoradiography and the involvement of nACh receptors in anti-nociceptive effects in the region where changes occurred. KEY RESULTS: Autoradiographic studies showed that the accumulation of [(125)I]5IA and the number of nACh receptors in the thalamus of PSL rats were increased about twofold compared with those in the sham-operated rats. No change was observed in other brain regions. Rats injected in the ventral posterolateral thalamic nucleus (VPL) with 5IA demonstrated a significant and dose-dependent anti-allodynic effect and this effect was completely antagonized by mecamylamine, injected with 5IA, into the VPL. The blockade of nACh receptors in the VPL by mecamylamine decreased by 70% the anti-allodynic effect of 5IA, given i.c.v. Moreover, mecamylamine given intra-VPL by itself, induced significant hyperalgesia. CONCLUSIONS AND IMPLICATIONS: Our findings suggest that the nACh receptors expressed in the VPL play an important role in the anti-allodynic effects produced by exogenous and endogenous agonists.


Subject(s)
Azetidines/therapeutic use , Nicotinic Agonists/therapeutic use , Pain/drug therapy , Pyridines/therapeutic use , Receptors, Nicotinic/biosynthesis , Sciatic Neuropathy/drug therapy , Ventral Thalamic Nuclei/drug effects , Animals , Autoradiography , Azetidines/pharmacokinetics , Azetidines/pharmacology , Disease Models, Animal , Iodine Radioisotopes , Male , Nicotinic Agonists/pharmacokinetics , Nicotinic Agonists/pharmacology , Pain/metabolism , Pain Threshold , Pyridines/pharmacokinetics , Pyridines/pharmacology , Rats , Rats, Sprague-Dawley , Receptors, Nicotinic/physiology , Sciatic Neuropathy/metabolism , Ventral Thalamic Nuclei/metabolism
8.
J Oral Rehabil ; 36(9): 627-35, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19602100

ABSTRACT

To examine the stiffness of the masseter muscle using sonographic elastography and to investigate its relationship with the most comfortable massage pressure in the healthy volunteers. In 16 healthy volunteers (10 men and 6 women), the Masseter Stiffness Index (MSI) was measured using EUB-7000 real-time tissue elastography. They underwent massages at three kinds of pressures using the Oral Rehabilitation Robot (WAO-1). A subjective evaluation regarding the comfort of each massage was recorded on the visual analogue scale. Elastography was also performed in two patients with temporomandibular joint dysfunction with the myofascial pain. The mean MSI of the right and left muscles in the healthy volunteers were 0.85 +/- 0.44 and 0.74 +/- 0.35 respectively. There was no significant difference between the right and left MSI in the healthy volunteers. The MSI was related to massage pressure at which the healthy men felt most comfortable. The two temporomandibular disorder patients had a large laterality in the MSI. The MSI was related to the most comfortable massage pressure in the healthy men. The MSI can be one index for determining the massage pressure.


Subject(s)
Elasticity Imaging Techniques/methods , Massage/methods , Masseter Muscle/diagnostic imaging , Temporomandibular Joint Dysfunction Syndrome/rehabilitation , Adult , Elasticity Imaging Techniques/instrumentation , Female , Humans , Male , Massage/instrumentation , Masseter Muscle/physiology , Middle Aged , Pain Measurement , Pressure , Sensory Thresholds , Temporomandibular Joint Dysfunction Syndrome/diagnostic imaging
9.
Kyobu Geka ; 62(4): 328-31, 2009 Apr.
Article in Japanese | MEDLINE | ID: mdl-19348219

ABSTRACT

Although traumatic rupture of the thoracic aorta has been considered a surgical emergency, we report here an example of successful delayed surgery for acute traumatic rupture of the aortic arch with an isolated left vertebral artery in an 18-year-old woman. The patient was.admitted to the intensive care unit with hemothorax and, rib fractures, and a decision was made to treat the aortic injury conservatively until the patient was stabilized. She underwent surgery after 3 months of observation. After the isolated left vertebral artery had been anastomosed to the left carotid artery, total arch replacement was performed. Delayed surgery for aortic rupture as a treatment choice may be of benefit in selected cases of complex trauma.


Subject(s)
Aorta, Thoracic/injuries , Aorta, Thoracic/surgery , Blood Vessel Prosthesis Implantation , Vertebral Artery/abnormalities , Adolescent , Anastomosis, Surgical , Carotid Arteries/surgery , Female , Humans , Rupture , Time Factors , Treatment Outcome , Vascular Surgical Procedures , Vertebral Artery/surgery
10.
Int J Oral Maxillofac Surg ; 38(3): 296-9, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19167190

ABSTRACT

A case of large cell neuroendocrine carcinoma (LCNEC) of the tongue base is described. It was characterized by solid tumor nests with central necrosis and rosette formation resembling basaloid squamous cell carcinoma. Immunohistochemical examination revealed that this tumor had neuroendocrine differentiation. It was diagnosed as LCNEC of the tongue base. Pulmonary LCNEC is a well-established entity, but LCNEC also occurs in other organs. This is the first report of mucosal LCNEC in the oral cavity. Basal cells in the normal squamous epithelium around the tumor indicated positivity for neural cell adhesion molecule and N-cadherin. These cells were considered neuroendocrine-related cells in the lingual squamous epithelium, which are related to the tumorigenesis of mucosal LCNEC in the tongue base.


Subject(s)
Carcinoma, Large Cell/pathology , Carcinoma, Neuroendocrine/pathology , Carcinoma, Squamous Cell/pathology , Neoplasms, Multiple Primary/pathology , Tongue Neoplasms/pathology , Aged , Antigens, Neoplasm/immunology , Carcinoma, Large Cell/immunology , Carcinoma, Large Cell/surgery , Carcinoma, Neuroendocrine/immunology , Carcinoma, Neuroendocrine/surgery , Carcinoma, Squamous Cell/immunology , Carcinoma, Squamous Cell/surgery , Diagnosis, Differential , Humans , Hypopharyngeal Neoplasms/pathology , Hypopharyngeal Neoplasms/surgery , Immunohistochemistry , Male , Neoplasms, Multiple Primary/surgery , Tongue Neoplasms/immunology , Tongue Neoplasms/surgery , Treatment Outcome
11.
Phytopathology ; 98(10): 1099-106, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18943456

ABSTRACT

Fusarium oxysporum produces three kinds of asexual spores, microconidia, macroconidia, and chlamydospores. We previously found that the transcript level of the nitrite reductase gene of F. oxysporum, named FoNIIA, was markedly upregulated during conidiation compared with during vegetative growth. FoNIIA was also found to be positively regulated by Ren1 that is a transcription regulator controlling development of microconidia and macroconidia. In this study, we analyzed the function of FoNIIA in conidiation of F. oxysporum. Conidiation cultures showed markedly higher level of accumulation of FoNiiA protein as well as FoNIIA mRNA than vegetative growth cultures. FoNIIA protein was significantly decreased in cultures of the REN1 disruption mutant compared with that of the wild type. These results confirmed that FoNIIA expression is upregulated during conidiation and is positively regulated by REN1. The FoNIIA disruption mutants produced microconidia, macroconidia, and chlamydospores, which were morphologically indistinguishable from those of the wild type. The mutants, however, produced significantly fewer macroconidia than the wild type, although the wild type and mutant strains produced similar numbers of microconidia and chlamydospores. These results demonstrate that nitrite reductase is involved in quantitative control of macroconidium formation as well as nitrate utilization in F. oxysporum.


Subject(s)
Fusarium/genetics , Nitrite Reductases/genetics , Amino Acid Sequence , Cloning, Molecular , DNA Primers , Darkness , Fungal Proteins/genetics , Fusarium/enzymology , Fusarium/growth & development , Light , Molecular Sequence Data , Reverse Transcriptase Polymerase Chain Reaction , Soil Microbiology , Solanum tuberosum/microbiology , Spores, Fungal/enzymology , Spores, Fungal/genetics , Transcription, Genetic , Up-Regulation
12.
Dentomaxillofac Radiol ; 37(3): 130-5, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18316503

ABSTRACT

OBJECTIVES: To compare the responses of oropharyngeal structures to gravity while sitting upright or lying down in a supine position. METHODS: Seven subjects were evaluated by cone beam CT (CBCT) while in the upright position and by a four-row multidetector helical CT (MDCT) while in the supine position. All of the voxel sizes were adjusted to be 0.3x0.3x0.3 mm3 in the x-y-z axis. The posterior nasal spine, basion and fourth cervical bone were used as references to measure positional changes in the oropharyngeal structures between the upright and supine positions. The smallest areas in the oropharynx were also evaluated. RESULTS: The soft palate, epiglottis and entrance of the oesophagus moved caudally with the positional change from supine to sitting upright, and moved posteriorly when the position changed from an upright to a supine position. The hyoid bone moved caudally but not posteriorly in response to the same positional changes. The width and length of the smallest area present in the oropharynx was larger in the upright position than in the supine position. CONCLUSIONS: Gravity can produce movements in oropharyngeal structures in response to postural changes between sitting upright and lying in the supine position.


Subject(s)
Oropharynx/anatomy & histology , Posture/physiology , Supine Position/physiology , Adult , Cephalometry/methods , Cervical Vertebrae/anatomy & histology , Cone-Beam Computed Tomography/methods , Epiglottis/anatomy & histology , Esophagus/anatomy & histology , Female , Gravitation , Humans , Hyoid Bone/anatomy & histology , Image Processing, Computer-Assisted/methods , Male , Middle Aged , Nasal Bone/anatomy & histology , Palate, Soft/anatomy & histology , Tomography, Spiral Computed/methods
13.
Genes Immun ; 7(8): 647-54, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17024131

ABSTRACT

The F(1) hybrid of autoimmune hemolytic anemia-prone NZB and nonautoimmune NZW strains of mice has been studied as a murine model of systemic lupus erythematosus. Both NZB and F(1) hybrid mice show age-dependent spontaneous activation of peripheral CD4(+) T cells as reflected by the elevated frequencies of CD4(+) T cells positive for CD69 early activation marker. Both strains also show age-dependent abnormal decrease of the frequencies of CD62L(+) naive CD4(+) T cells and/or NTA260(+) memory CD4(+) T cells in the spleen. We studied the multigenic control of these abnormal features of peripheral CD4(+) T cells in (NZB x NZW) F(1) x NZW backcross mice by quantitative trait loci mapping and by association rule analysis. The abnormally elevated frequencies of CD69(+)CD4(+) T cells and decreased frequencies of CD62L(+) naive and/or NTA260(+) memory CD4(+) T cells were under the common genetic control, in which the interaction between MHC and a hitherto unknown locus, designated Sta-1 (spontaneous T-cell activation) on chromosome 12, plays a major role. The allelic effects of these loci likely predispose CD4(+) T cells to the loss of self-tolerance, and are responsible for the accelerated autoimmune phenotypes of (NZB x NZW) F(1) hybrid mice.


Subject(s)
Autoimmunity/genetics , Lupus Erythematosus, Systemic/genetics , Lupus Erythematosus, Systemic/immunology , Lymphocyte Activation/genetics , T-Lymphocytes, Helper-Inducer/immunology , Age Factors , Animals , Antibodies, Monoclonal/immunology , Antigens, CD/metabolism , Antigens, Differentiation, T-Lymphocyte/metabolism , Chromosome Mapping , Crosses, Genetic , Flow Cytometry , L-Selectin/metabolism , Lectins, C-Type , Mice , Mice, Inbred NZB , Microsatellite Repeats/genetics , Quantitative Trait Loci/genetics , Spleen/metabolism , T-Lymphocytes, Helper-Inducer/metabolism
14.
Kyobu Geka ; 59(7): 580-4, 2006 Jul.
Article in Japanese | MEDLINE | ID: mdl-16856535

ABSTRACT

A 78-year-old female was admitted to our hospital because of sudden onset of chest pain and general fatigue. A chest X-ray showed marked cardiomegaly and computed tomography (CT) revealed pericardial effusion with left pleural effusion. Upon admission to CCU, she suddenly lost consciousness and was intubated. Echocardiography confirmed increase in the amount of the pericardial effusion, which was drained at CCU. By an emergent operation, ruptured aneurysm of the noncoronary sinus of Valsalva to the pericardial space was confirmed upon opening the chest and patch plasty of the sinus of Valsalva was performed. The postoperative course was uneventful, and she was discharged on the 24th postoperative day. Extracardiac rupture of aneurysm of the sinus of Valsalva is extremely rare, and the emergent operation is indispensable.


Subject(s)
Aortic Aneurysm/surgery , Aortic Rupture/surgery , Sinus of Valsalva , Aged , Aortic Aneurysm/diagnostic imaging , Aortic Rupture/diagnostic imaging , Cardiac Surgical Procedures/methods , Female , Fibrin Tissue Adhesive , Humans , Sinus of Valsalva/surgery , Ultrasonography
15.
Gene Ther ; 13(11): 906-16, 2006 Jun.
Article in English | MEDLINE | ID: mdl-16511524

ABSTRACT

Catheter-mediated, percutaneous, transluminal delivery of naked plasmid DNA (pDNA) into myocardium may offer a valuable strategy to heart diseases. Here, we examined whether clinically available transthoracic direct current (DC) shock improves intracoronary naked DNA transfection into myocardium. Plasmid vector encoding the GL3 luciferase was infused retrogradely into the coronary veins of beagle dogs, whereas another pDNA solution was infused into the left coronary artery. During and after these procedures, the coronary venous sinus was occluded by balloon, and transthoracic DC shock of 200 J was applied immediately after the infusions. Without DC shock, no remarkable increase in luciferase activity was demonstrated in any part of the left ventricular myocardium. In the presence of DC pulsation, significant luciferase expression was detected in the regions that were supplied by left anterior descending coronary artery (LAD), whereas the gene expression in the right coronary artery (RCA) regions was much less drastic. X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactoside) staining of cardiac cross-sections also revealed regional expression of beta-galactosidase. Immunohistochemical examinations of heart cryosections revealed that cardiomyocytes in LAD regions successfully expressed transgene product. The present system may enable a new strategy for myocardial gene therapy, without any special device or technique other than cardiac catheterization and DC cardioversion that are generally performed in ordinary hospitals.


Subject(s)
DNA/administration & dosage , Genetic Therapy/methods , Heart Diseases/therapy , Myocardium/metabolism , Transfection/methods , Animals , Cardiac Catheterization , Coronary Vessels , Dogs , Electric Stimulation , Electrocardiography , Electromyography , Female , Gene Expression , Immunohistochemistry/methods , Luciferases/analysis , Luciferases/genetics
16.
Cell Mol Biol (Noisy-le-grand) ; 51 Suppl: OL767-84, 2005 Sep 02.
Article in English | MEDLINE | ID: mdl-16171576

ABSTRACT

This review focuses on a unique transdermal drug delivery enhanced by the action of ultrasound, referred as sonophoresis. Sonophoresis is an active form of transdermal delivery which enhances the transport of permeants, such as drugs through cell membranes as a result of ultrasonic energy. Ultrasonic sound waves cause acoustic cavitation, the resultant effects of which microscopically disrupt the lipid bilayers of the stratum corneum and thereby influencing the influx of permeants. Sonophoresis increases the penetration of various low molecular weight drugs as well as high molecular weight proteins. The objective of this review is to account the role of ultrasound parameters and the associated cavitational effects, gained through a number of investigations, in order to facilitate the understanding of this method.


Subject(s)
Drug Delivery Systems/methods , Ultrasonics , Administration, Cutaneous , Pharmaceutical Preparations/administration & dosage , Skin/anatomy & histology
17.
Ultrason Sonochem ; 12(1-2): 73-7, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15474955

ABSTRACT

Volumetric oscillation of multiple cavitation bubbles in an ultrasonic standing-wave field is investigated spatially through the intensity measurements of scattered light from bubbles changing the measuring position in the direction of sound propagation. When a thin light sheet finer than half of wavelength of sound is introduced into the cavitation bubbles, at an antinode of sound pressure the scattered light intensity oscillates. The peak-to-peak light intensity corresponds to the number of the bubbles which contribute to the sonochemical reaction because the radius for oscillating bubbles at pressure antinodes is restrictive in a certain range due to the shape instability and the action of Bjerknes force that expels from the antinode bubbles that are larger than the resonant size. The experimental results show that the intensity waveform of oscillating scattered light measured at the side near the sound source is similar to the waveform as seen in a single-bubble experiment. The peak-to-peak light intensity for the scattered light waveform is low at the side near the sound source where the progressive wave is dominant, while at the side near the water surface far from the sound source the intensity is relatively high and has periodic structure corresponding to the periodicity of half wavelength from the standing wave. These tendencies of high intensity near the water surface and the periodicity correspond to the periodic luminescent stripes seen in images of luminescence in an ultrasonic standing wave as reported by Hatanaka et al. [Jpn. J. Appl. Phys. 39 (2000) 2962]. The present method of light scattering is promising for evaluating spatial distribution of violently oscillating cavitation bubbles which effect sonochemical reactions.


Subject(s)
Gases/analysis , Gases/chemistry , Lasers , Microspheres , Nephelometry and Turbidimetry/instrumentation , Sonication/instrumentation , Water/chemistry , Dose-Response Relationship, Radiation , Equipment Design , Equipment Failure Analysis , Gases/radiation effects , Nephelometry and Turbidimetry/methods , Oscillometry/instrumentation , Radiation Dosage , Scattering, Radiation , Solutions
18.
Ultrasonics ; 42(1-9): 597-601, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15047353

ABSTRACT

Enhancement of chemical reaction with a photocatalyst of titanium dioxide (TiO(2)) by ultrasonic irradiation is studied through the absorbance measurements for liberation of iodine from a KI aqueous solution as an index of oxidation reaction. It is well known as a synergetic effect that the addition of TiO(2) fine particles under UV has an ability to enhance the yield in chemical reaction with OH-radical from hot spot at violent collapse of cavitation bubbles with intense ultrasound. In this study, the absorbance is measured after simultaneous irradiation of ultrasound and UV with the addition of TiO(2) much less than the usual concentration by two orders of content. It is shown that, even in case of quite a little TiO(2) addition where the photocatalytic effect is less, the yield is enhanced obviously in comparison with the summation in yield of independent procedure of ultrasound without TiO(2) and UV with TiO(2). The absorbance-peak deviation to the shorter wavelength implies the generation of titanium peroxide (TiO(3)). The effect of particle addition is due to the chemically activated particle surface on the TiO(2) and probably to the increase in the cavitation bubbles that results in promoting a transfer of OH-radical and other oxidants to bulk liquid region at the collapse.

19.
Ultrasonics ; 42(1-9): 635-9, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15047359

ABSTRACT

Removal of Methyl orange (MO), as a model contaminants, in aqueous solution by the simultaneous application of ultrasound with the addition of porous adsorbent powders is reported. Activated alumina powders in acidic form were used as an adsorbent. Results showed that MO could be degraded by ultrasonic irradiation at 130 kHz with the first order rate constant of 8x10(-4) and 5x10(-4) sec(-1), in acidic and basic conditions, respectively, without adsorbents. Adsorption rates of MO by activated alumina mainly depended on the acidity of alumina, the pH of solution and the stirring speed. At pH=4.2 with mechanical stirring without ultrasonic radiation, acidic activated alumina (0.1 g/100 ml) removed MO at about two times more rapidly than ultrasonic irradiation. In the case of simultaneous application of ultrasound irradiation and activated alumina, MO was almost removed from the solution within 10 min, which corresponded to as a rate constant of 5x10(-3) sec(-1). This kind of synergistic enhancement of removal rate with ultrasound and adsorbents should be practically useful for the elimination of contaminants in the water treatment processes. In addition, the effects of pH and coexisting chemicals in the solution were examined for the processes. Although the adsorption process was effective in some selected conditions, ultrasonic degradation was more robust in wider range of pH and coexisting chemicals. Simultaneous application of the two processes can perform complementary.

20.
Talanta ; 64(5): 1278-82, 2004 Dec 15.
Article in English | MEDLINE | ID: mdl-18969742

ABSTRACT

An acid urease column was applied to a fluorometric flow-injection analysis (FIA) system as a recognition element for determination of urea in rice wines. The acid urease has specific properties of showing its catalytic activity in low pH range and tolerance to ethanol in comparison to those of a urease from jack-beans. The enzymes were covalently immobilized onto porous glass beads with controlled pore size and then, packed into a small polymer column. The flow-type of the biosensing system was assembled with a sample injection valve, the immobilized enzyme column, and a flow-through quartz cell attached to a fluorescent spectrophotometer. Citrate buffer (50mM, pH 5.0) as the carrier solution was continuously pumped through the system. Sample solutions were introduced into the system via a rotary injection valve. A standard urea solution was measured through monitoring variations in fluorescent intensity attributable to fluorescent isoindole derivatives formed by coupling with ammonia molecules released in the enzymatic hydrolysis of urea and orthophthalaldehyde reagents. The fluorescent intensity was measured under the conditions of lambda(ex) = 415nm and lambda(em) = 485nm. A wide, linear relationship was obtained between the concentration of urea (1.0-100muM) and the variation in fluorescent intensity. The monitoring did not suffer from ethanol and various amino acids contained in rice wines. Real samples pretreated with ion exchange resins for removal of endogenous ammonia were introduced into the FIA system and urea in the samples was determined. These results were compared with those obtained with use of an F-kit method. The proposed FIA system should present sensitive, selective and convenient analysis of urea in alcoholic beverages.

SELECTION OF CITATIONS
SEARCH DETAIL
...