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1.
Biochim Biophys Acta Mol Basis Dis ; 1870(5): 167138, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38537683

RESUMEN

Obg-like ATPase 1 (OLA1) is a binding protein of Breast cancer gene 1 (BRCA1), germline pathogenic variants of which cause hereditary breast cancer. Cancer-associated variants of BRCA1 and OLA1 are deficient in the regulation of centrosome number. Although OLA1 might function as a tumor suppressor, the relevance of OLA1 deficiency to carcinogenesis is unclear. Here, we generated Ola1 knockout mice. Aged female Ola1+/- mice developed lymphoproliferative diseases, including malignant lymphoma. The lymphoma tissues had low expression of Ola1 and an increase in the number of cells with centrosome amplification. Interestingly, the proportion of cells with centrosome amplification in normal spleen from Ola1+/- mice was higher in male mice than in female mice. In human cells, estrogen stimulation attenuated centrosome amplification induced by OLA1 knockdown. Previous reports indicate that prominent centrosome amplification causes cell death but does not promote tumorigenesis. Thus, in the current study, the mild centrosome amplification observed under estrogen stimulation in Ola1+/- female mice is likely more tumorigenic than the prominent centrosome amplification observed in Ola1+/- male mice. Our findings provide a possible sex-dependent mechanism of the tumor suppressor function of OLA1.


Asunto(s)
Proteína BRCA1 , Centrosoma , Estrógenos , Ratones Noqueados , Animales , Femenino , Humanos , Masculino , Ratones , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Centrosoma/metabolismo , Estrógenos/metabolismo , Linfoma/metabolismo , Linfoma/genética , Linfoma/patología
2.
Cureus ; 15(12): e50476, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38094881

RESUMEN

Despite the potential of cardiac rehabilitation (CR) to reduce atrial fibrillation (AF) recurrence after radiofrequency catheter ablation (RFCA), its prescription is not routine. We conducted a systematic review and meta-analysis to evaluate the safety and efficacy of CR in this setting. Inclusion criteria comprised randomized controlled trials (RCTs) comparing CR with usual care in patients with AF following RFCA. We performed a comprehensive search of six databases up to August 17, 2023, and conducted a thorough risk of bias assessment. We synthesized safety outcomes using AF recurrence rates to calculate relative risks (RR). Furthermore, we conducted a meta-analysis on peak oxygen uptake (VO2 peak) and the six-minute walk test (6MWT) to gauge efficacy, utilizing mean differences (MD) for comparison. The GRADE framework was employed to determine the certainty of evidence, with two independent reviewers completing all processes. Our analysis encompassed eight studies with 772 participants aged 55-70 years engaged in moderate-intensity CR for a median of six months. Results showed no significant difference in AF recurrence after CR (RR = 0.69 (0.41-1.14)), with low evidence certainty due to heterogeneity. Subgroup analyses suggested a poor risk reduction effect in patients with obesity and persistent AF. Significant improvements were observed in VO2 peak and 6MWT outcomes (VO2 peak; MD = 2.53 (0.78-4.28), 6MWT; MD = 38.81 (0.65-76.97)), with moderate-certainty evidence. While CR may decrease AF recurrence after RFCA, its effectiveness varies, potentially diminishing in patients with obesity or persistent AF. Moderate gains in physical performance were achieved with minimal adverse events. Further RCTs are warranted to confirm these findings.

3.
Materials (Basel) ; 16(20)2023 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-37895658

RESUMEN

Accumulation and concentration of debris in deep hole electrical discharge machining (EDM) significantly hinder its machining efficiency and accuracy. It is believed that the movement of bubbles associated with the discharge gap flow field play a pivotal role in debris removal and influence the discharge conditions. Ultrasonic vibration (USV) of the electrode is thought to be an effective method for improving EDM-generated bubbles and debris exclusion. In this study, we first elucidated the behavior of bubbles during EDM of holes with varying aspect ratios. Subsequently, USV was introduced to EDM. The behavior of dielectric fluid flow under the influence of ultrasonic vibration was analyzed using computational fluid dynamics (CFD), which revealed time-varying changes in discharge gap flow pressure and velocity. The velocity of the dielectric flow field near the electrode's side face was found to reach a maximum of approximately 15.2 m/s, greatly facilitating debris removal. High-speed camera observations revealed that bubbles were dispersed within the side gap, with most of them adhering to the electrode's wall. Furthermore, the bubbles exhibited a tendency to continuously break up and coalesce near the hole's outlet before escaping in the USV-assisted EDM. These observed characteristics of bubble behavior under the influence of USV are expected to significantly enhance debris removal and promote efficient dielectric exchange.

4.
Materials (Basel) ; 15(18)2022 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-36143642

RESUMEN

This paper deals with a non-destructive analysis of residual stress through the visualization of deformation behaviors induced by a local spot heating. Deformation was applied to the surface of an aluminum alloy with an infrared spot laser. The heating process is non-contact, and the applied strain is reversible in the range of room temperature to approximately +10 °C. The specimen was initially pulled up to elastic tensile stress using a tensile test machine under the assumption that the material was subject to the tensile residual stress. The relaxation behaviors of the applied strain under tensile stress conditions were evaluated using contact and non-contact methods, i.e., two strain gauges (the contact method) and a two-dimensional electronic speckle pattern interferometer (non-contact method). The results are discussed based on the stress dependencies of the thermal expansion coefficient and the elasticity of the materials.

5.
Antimicrob Agents Chemother ; 66(2): e0160821, 2022 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-34843388

RESUMEN

A population pharmacokinetic analysis of delamanid and its major metabolite DM-6705 was conducted to characterize the pharmacokinetics of delamanid and DM-6705 in pediatric participants with multidrug-resistant tuberculosis (MDR-TB). Data from participants between the ages of 0.67 and 17 years, enrolled in 2 clinical trials, were utilized for the analysis. The final data set contained 634 delamanid and 706 DM-6705 valid plasma concentrations from 37 children. A transit model with three compartments best described the absorption of delamanid. Two-compartment models for each component with linear elimination were selected to characterize the dispositions of delamanid and DM-6705, respectively. The covariates included in the model were body weight on the apparent volume of distribution and apparent clearance (for both delamanid and DM-6705); formulation (dispersible versus film-coated tablet) on the mean absorption time; age, formulation, and dose on the bioavailability of delamanid; and age on the fraction of delamanid metabolized to DM-6705. Based on the simulations, doses for participants within different age/weight groups that result in delamanid exposure comparable to that in adults following the approved adult dose were calculated. By concentration-QTc (QTcB [QT corrected by Bazett's formula]) analysis, a significant positive correlation was detected with concentrations of DM-6705. However, the model-predicted upper bounds of the 90% confidence intervals of ΔQTc values were <10 ms at the simulated maximum concentration (Cmax) of DM-6705 following the administration of the maximum doses simulated. This suggests that the effect on the QT interval following the proposed dosing is unlikely to be clinically meaningful in children with MDR-TB who receive delamanid.


Asunto(s)
Nitroimidazoles , Tuberculosis Resistente a Múltiples Medicamentos , Adolescente , Adulto , Antituberculosos/farmacocinética , Antituberculosos/uso terapéutico , Niño , Preescolar , Humanos , Lactante , Nitroimidazoles/uso terapéutico , Oxazoles/uso terapéutico , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico
6.
Antimicrob Agents Chemother ; 65(8): e0257120, 2021 07 16.
Artículo en Inglés | MEDLINE | ID: mdl-34097484

RESUMEN

Delamanid has been studied extensively and approved for the treatment of pulmonary multidrug-resistant tuberculosis; however, its potential in the treatment of extrapulmonary tuberculosis remains unknown. We previously reported that, in rats, delamanid was broadly distributed to various tissues in addition to the lungs. In this study, we simulated human plasma concentration-time courses (pharmacokinetic profile) of delamanid, which has a unique property of metabolism by albumin, using two different approaches (steady-state concentration of plasma-mean residence time [Css-MRT] and physiologically based pharmacokinetic [PBPK] modeling). In Css-MRT, allometric scaling predicted the distribution volume at steady state based on data from mice, rats, and dogs. Total clearance was predicted by in vitro-in vivo extrapolation using a scaled albumin amount. A simulated human pharmacokinetic profile using a combination of human-predicted Css and MRT was almost identical to the observed profile after single oral administration, which suggests that the pharmacokinetic profile of delamanid could be predicted by allometric scaling from these animals and metabolic capacity in vitro. The PBPK model was constructed on the assumption that delamanid was metabolized by albumin in circulating plasma and tissues, to which the simulated pharmacokinetic profile was consistent. Moreover, the PBPK modeling approach demonstrated that the simulated concentrations of delamanid at steady state in the lung, brain, liver, and heart were higher than the in vivo effective concentration for Mycobacterium tuberculosis. These results indicate that delamanid may achieve similar concentrations in various organs to that of the lung and may have the potential to treat extrapulmonary tuberculosis.


Asunto(s)
Nitroimidazoles , Tuberculosis , Animales , Antituberculosos/uso terapéutico , Perros , Humanos , Ratones , Modelos Biológicos , Oxazoles , Ratas , Tuberculosis/tratamiento farmacológico
7.
Materials (Basel) ; 14(6)2021 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-33804797

RESUMEN

The deformation and fracture mechanism in 7075 aluminum alloy is discussed based on a field theoretical approach. A pair of peak-aged and overaged plate specimens are prepared under the respective precipitation conditions, and their plastic deformation behaviors are visualized with two-dimensional electronic speckle pattern interferometry (ESPI). The in-plane velocity field caused by monotonic tensile loading is monitored continuously via the contour analysis method of ESPI. In the plastic regime, the peak-aged specimen exhibits a macroscopically uniform deformation behavior, while the annealed specimen exhibits non-uniform deformation characterized by a localized shear band. The occurrence of the shear band is explained by the transition of the material's elastic resistive mechanism from the longitudinal force dominant to shear force dominant mode. The shear force is interpreted as the frictional force that drives mobile dislocations along the shear band. The dynamic behavior of the shear band is explained as representing the motion of a solitary wave. The observed decrease in the solitary wave's velocity is accounted for by the change in the acoustic impedance with the advancement of plastic deformation.

8.
Anal Sci ; 37(8): 1185-1188, 2021 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-33551440

RESUMEN

We built a heating furnace using stainless-steel instead of aluminum in gas chromatography combined with an oxidation/reduction system; it increased the oxidation temperature to 650°C. At 600°C, it completely oxidized five organochlorine compounds. This system was applied to a standard solution of 23 volatile organic compounds. The analytical results of 20 hydrocarbon and organochlorine compounds showed good agreement with the expanded uncertainty (k = 2) of the reference values. Three organobromine compounds obtained values higher than the reference; this was investigated further.

9.
Sci Rep ; 10(1): 18195, 2020 10 23.
Artículo en Inglés | MEDLINE | ID: mdl-33097801

RESUMEN

Patients with non-dialysis chronic kidney disease (CKD) are at greater risk of early mortality and decreased physical function with an advance in the stage of CKD. However, the effect of exercise in these patients is unclear. This meta-analysis aimed to determine the effects of physical exercise training on the risk of mortality, kidney and physical functions, and adverse events in patients with non-dialysis CKD. The meta-analysis conformed to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement and the Cochrane Handbook recommendations. On 16 August 2019, the PubMed, CINAHL, Cochrane Library databases, and Embase were electronically searched, with no restrictions for date/time, language, document type, or publication status, for eligible randomized controlled trials (RCTs) investigating the effects of exercise on mortality and kidney and physical function in patients with non-dialysis CKD. Eighteen trials (28 records), including 848 patients, were analyzed. The effects of exercise on all-cause mortality and estimated glomerular filtration rate were not significantly different from that of usual care. Exercise training improved peak/maximum oxygen consumption compared to usual care. Regular exercise improves physical and walking capacity for patients with non-dialysis CKD. Effect on leg muscle strength was unclear.


Asunto(s)
Ejercicio Físico , Fallo Renal Crónico/fisiopatología , Adulto , Tasa de Filtración Glomerular/fisiología , Humanos , Consumo de Oxígeno , Calidad de Vida , Caminata
10.
Artículo en Inglés | MEDLINE | ID: mdl-33106263

RESUMEN

Pharmacokinetic (PK) and pharmacodynamic (PD) analyses were conducted to determine the cumulative fraction of response (CFR) for 100 mg twice-daily (BID) and 200 mg once-daily (QD) delamanid in patients with multidrug-resistant tuberculosis (MDR-TB), using a pharmacodynamic target (PDT) that achieves 80% of maximum efficacy. First, in the mouse model of chronic TB, the PK/PD index for delamanid efficacy was determined to be area under the drug concentration-time curve over 24 h divided by MIC (AUC0-24/MIC), with a PDT of 252. Second, in the hollow-fiber system model of tuberculosis, plasma-equivalent PDTs were identified as an AUC0-24/MIC of 195 in log-phase bacteria and 201 in pH 5.8 cultures. Third, delamanid plasma AUC0-24/MIC and sputum bacterial decline data from two early bactericidal activity trials identified a clinical PDT of AUC0-24/MIC of 171. Finally, the CFRs for the currently approved 100-mg BID dose were determined to be above 95% in two MDR-TB clinical trials. The CFR for the 200-mg QD dose, evaluated in a trial in which delamanid was administered as 100 mg BID for 8 weeks plus 200 mg QD for 18 weeks, was 89.3% based on the mouse PDT and >90% on the other PDTs. QTcF (QTc interval corrected for heart rate by Fridericia's formula) prolongation was approximately 50% lower for the 200 mg QD dose than the 100 mg BID dose. In conclusion, while CFRs of 100 mg BID and 200 mg QD delamanid were close to or above 90% in patients with MDR-TB, more-convenient once-daily dosing of delamanid is feasible and likely to have less effect on QTcF prolongation.


Asunto(s)
Mycobacterium tuberculosis , Nitroimidazoles , Tuberculosis Resistente a Múltiples Medicamentos , Animales , Antituberculosos/uso terapéutico , Humanos , Ratones , Nitroimidazoles/uso terapéutico , Oxazoles , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico
11.
Materials (Basel) ; 13(6)2020 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-32192192

RESUMEN

A method to diagnose the deformation status of solid objects under loading is discussed. The present method is based on a recent field theory of deformation and fracture and optical interferometry known as the Electronic Speckle-Pattern Interferometry (ESPI). Using one of the most fundamental principles of physics referred to as symmetry in physics, this field theory formulates all stages of deformation and fracture on the same theoretical basis. In accordance with the formalism, the theory has defined the criteria for different stages of deformation (linear elastic, plastic and fracturing stages) expressed by certain spatiotemporal features of the differential displacement (the displacement occurring during a small time interval). The ESPI is used to visualize the differential displacement field of a specimen as two-dimensional, full-field interferometric fringe patterns. This paper reports experimental evidence that demonstrates the usefulness of the present method. A tensile load is applied to an aluminum-alloy plate specimen at a constant pulling rate and the resultant in-plane displacement field is visualized with a two-dimensional ESPI setup. The differential displacement field is obtained at each time step and the interferometric fringe patterns are interpreted based on the criterion for each stage of deformation. It has been found that the criteria of linear elastic deformation, plastic deformation and fracturing stage are clearly observed in the corresponding fringe patterns and that the observations are consistent with the loading characteristics.

12.
Materials (Basel) ; 12(24)2019 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-31835611

RESUMEN

This paper discusses a non-destructive measurement technique of residual stress through optical visualization. The least amount of deformation possible is applied to steel plates by heating the specimens +10 °C from room temperature for initial calibration, and the thermal expansion behavior is visualized with an electronic speckle pattern interferometer sensitive to two dimensional in-plane displacement. Displacement distribution with the thermal deformation and coefficient of thermal expansion are obtained through interferometric fringe analysis. The results suggest the change in the thermal deformation behavior is affected by the external stress initially applied to the steel specimen. Additionally, dissimilar joints of steel and cemented carbide plates are prepared by butt-brazing. The residual stress is estimated based on the stress dependence of thermal expansion coefficient.

13.
J Phys Ther Sci ; 31(5): 453-456, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-31164784

RESUMEN

[Purpose] Limited data are available regarding the outcomes of non-operative treatment for hip fractures. We investigated the factors associated with functional rehabilitation outcomes in patients undergoing non-operative treatment for hip fractures. [Participants and Methods] We investigated 57 patients with hip fractures who underwent non-operative treatment. We retrospectively analyzed medical or rehabilitation outcomes and functional outcomes (assessed using the Functional Independence Measure tool). We examined the association between functional outcomes and other factors and compared the medical and rehabilitation outcomes between mobile and immobile patients at the time of discharge. [Results] Of the 57 patients investigated, 15 (26.3%) were mobile at discharge. We observed a significant association between the Functional Independence Measure subscores (Motor and Cognitive) and serum albumin levels. Serum albumin levels and the Functional Independence Measure subscores (Motor and Cognitive) were significantly higher in mobile than in immobile patients. [Conclusion] We observed that functional outcomes at discharge in patients undergoing non-operative treatment for hip fractures were associated with serum albumin ratios and the Functional Independence Measure-Cognitive score.

14.
Plant Sci ; 284: 185-191, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31084871

RESUMEN

Transcriptional activation of ascorbate biosynthesis-associated genes under illumination is one of the important steps in ascorbate pool size regulation in photosynthetic tissues. Several biological processes within chloroplasts such as photosynthesis are required for this activation, suggesting functional chloroplasts to play a key role. We herein found that when grown on agar plate, ascorbate content in Arabidopsis non-photosynthetic tissues, roots, are unexpectedly almost comparable to that in shoots. The high accumulation of ascorbate was particularly observed in root regions closer to the root-hypocotyl junction, in which chloroplast development occurred because of a direct exposure to light. When chloroplast development in roots were further stimulated by shoot removal, the expression of biosynthetic genes, especially VTC2 gene that encodes GDP-l-galactose phosphorylase, was activated, resulting in an increase in ascorbate pool size. These positive effects were canceled when the roots were treated with a photosynthetic inhibitor. A null mutation in the LONG HYPOCOTYL 5 (HY5) gene almost completely inhibited root greening as well as the VTC2 expression. Overall, these findings show that chloroplast development can trigger the expression of ascorbate biosynthesis-associated genes not only in leaves but also in roots.


Asunto(s)
Arabidopsis/metabolismo , Ácido Ascórbico/biosíntesis , Cloroplastos/fisiología , Raíces de Plantas/metabolismo , Arabidopsis/fisiología , Ácido Ascórbico/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Regulación de la Expresión Génica de las Plantas , Genes de Plantas/fisiología , Redes y Vías Metabólicas , Raíces de Plantas/fisiología , Reacción en Cadena en Tiempo Real de la Polimerasa
15.
Anal Sci ; 35(8): 855-859, 2019 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-30956263

RESUMEN

In this study, in-door air semi-volatile organic compounds (SVOCs) including 2-ethyl-1-hexanol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (texanol), and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), which are scheduled for adding as regulated compounds concerning indoor air reference values in Japan, were quantitatively extracted using a solid-phase extraction-type collection device, followed by sensitively determined by gas chromatography-mass spectrometry. The developed method has shown a good extraction recovery up to an air sampling volume of 900 L. The extracted analytes were quantitatively and rapidly eluted by 7 mL of acetone. The limit of quantification of the analytes were 0.7, 2.1 and 0.2 ng L-1 in air sample at a sampling volume of 300 mL without any concentration of a desorption solvent. The developed method was applied to simultaneous determinations of the investigated target analytes and phthalate esters in real indoor air samples.

16.
Anal Sci ; 34(7): 853-857, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29998971

RESUMEN

In this work, we applied post-column reaction gas chromatography (GC) using a flame ionization detector (FID) system to study nitrogen-containing organic compounds (NOCs). The results were subsequently validated. After separation by column, the target components were converted to carbon dioxide using an oxidizing catalyst and then reduced to methane, followed by detection using an FID. SI-traceable testing mixtures containing NOCs (isoprocarb, napropamide, and pendimethalin) were prepared by the gravimetric blending method. These mixtures were analyzed using a post-column reaction GC-FID system; standard materials of hydrocarbons were used as calibrants in this analysis. The determined values were compared with the values obtained for samples prepared at the corresponding concentrations, and statistical analyses were performed in all cases. It was shown that the determined and prepared values agreed well with each other within the uncertainty limits.

17.
Anal Sci ; 34(10): 1149-1153, 2018 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-29887545

RESUMEN

In this study, a solid-phase extraction-type collection device, with styrene-divinylbenzene polymer particles (Sunpak-H) as the adsorbent, was used for the quantitative determination of phthalate esters in air samples. The collection and elution recoveries of eight volatile phthalate esters, i.e., dimethyl phthalate, diethyl phthalate, dipropyl phthalate, diisobutyl phthalate, dibutyl phthalate, butyl-benzyl phthalate, di(2-ethylhexyl) phthalate, and dioctyl phthalate, were quantitatively evaluated. All analytes were collected using the device up to a sampling volume of 10000 L at a sampling temperature of 35°C without breakthrough. During air collection, moisture was not trapped on the adsorbent. The collected analytes were completely eluted from the device by passing 3 mL of acetone. The eluted solvent was injected into a gas chromatography-mass spectrometry system after the eluted solvent was concentrated, if necessary. After washing the adsorbent using acetone, the device could be reused more than 50 times. The limit of quantification for the analytes was less than 1 ng L-1 in air at a sampling volume of 600 L with solvent concentration. This device was successfully applied for the quantitative determination of phthalate esters in real air samples, including indoor and in-car air.


Asunto(s)
Aire/análisis , Ésteres/química , Ácidos Ftálicos/análisis , Ácidos Ftálicos/química , Extracción en Fase Sólida/instrumentación , Adsorción , Ácidos Ftálicos/aislamiento & purificación
18.
Anal Sci ; 33(10): 1175-1180, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28993593

RESUMEN

A newly designed styrene-divinylbenzene copolymer adsorbent packed solid-phase extraction (SPE)-type collection device for the quantitative determination of airborne polycyclic aromatic hydrocarbons (PAHs) containing two to five rings is reported in this manuscript. This SPE-type collection device offers rapid, easy and quantitative elution of the analytes and easier reuse. A small collection device was initially developed for investigating the basic collection and elution performances of the adsorbent with respect to PAHs. The analytes were quantitatively collected on the adsorbent up to 3 m3 of air sampling at a sampling temperature of 35°C. The collected analytes were then completely eluted from the adsorbent by passing 3 mL of dichloromethane without carry-over of the analyte. During air collection, because no moisture was trapped on the adsorbent, the subsequent gas chromatography-mass spectrometric analysis was not influenced by moisture. Based on these successful performances, a wide-bore collection device was introduced for collecting larger air samples. After a quantitative investigation of the collection and elution performances of the wide-bore collection device, it device was successfully applied for precise determinations of PAHs in atmospheric air. Further application and employment of the device for the precise determination of semi-volatile organic compounds in environmental air samples is expected due to these excellent results.

19.
J Sep Sci ; 39(21): 4202-4208, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27677097

RESUMEN

A novel partitioning collection device comprising a glass cartridge packed with poly(dimethylsiloxane)-coated macroporous silica particles was developed for the precise quantification of polycyclic aromatic hydrocarbons in air. The analyte collection and elution performances achieved using different amounts of poly(dimethylsiloxane) coating were quantitatively evaluated. The sample retention power increased with increasing the coating, and more than 250 L of air could be collected without analyte breakthrough at a sampling temperature of 35°C. During the air collection, the moisture in the air was not retained on the particles due to the hydrophobic surface of the sorbent. A complete and rapid elution of the collected analytes from the device was accomplished by the passage of only 10 mL of acetone with ultrasonication for 1 min. The proposed method was successfully applied for the determination of airborne polycyclic aromatic hydrocarbons in tunnel air.

20.
Ultrasonics ; 67: 9-17, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26773788

RESUMEN

This paper presents the results from a set of experiments designed to ultrasonically measure the near surface stresses distributed within a dissimilar metal welded plate. A scanning acoustic microscope (SAM), with a tone-burst ultrasonic wave frequency of 200 MHz, was used for the measurement of near surface stresses in the dissimilar welded plate between 304 stainless steel and low carbon steel. For quantitative data acquisition such as leaky surface acoustic wave (leaky SAW) velocity measurement, a point focus acoustic lens of frequency 200 MHz was used and the leaky SAW velocities within the specimen were precisely measured. The distributions of the surface acoustic wave velocities change according to the near-surface stresses within the joint. A three dimensional (3D) finite element simulation was carried out to predict numerically the stress distributions and compare with the experimental results. The experiment and FE simulation results for the dissimilar welded plate showed good agreement. This research demonstrates that a combination of FE simulation and ultrasonic stress measurements using SAW velocity distributions appear promising for determining welding residual stresses in dissimilar material joints.

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