Ultrasonic Apparatus Research Articles

Assessment of hepatic fat content in using quantitative ultrasound measurement of hepatic/renal ratio and hepatic echo-intensity attenuation rate.

This study aims to evaluate and validate a simple quantitative ultrasound (US) method for determining the hepatic fat content (HFC) based on the combination of quantitative US hepatic/renal ratio (US-HRR) and quantitative US hepatic echo-intensity attenuation rate (US-HAR) as compared with [1H]-magnetic resonance spectroscopy (1H-MRS). There were a total of 242 subjects recruited in the present study. All subjects were examined for HFC by quantitative US and 1H-MRS methods. The QUS-HRR and QUS-HAR were calculated from ordinary ultrasound images of liver and kidney with a triple modality 3D abdominal phantom using the Image J software. The results found that US-HRR and US-HAR correlated with 1H-MRS HFC (US-HRR: r=0.946, p<0.001; US-HAR: r=0.936, p<0.001). The equation for HFC prediction by using quantitative US was: HFC (%) = 28.965 × US-HRR + 218.045 × US-HAR - 8.892. Subgroup analysis in study subjects with body mass index (BMI) ≥28 showed that quantitative US HFC was associated with 1H-MRS HFC (R2=0.953, p<0.001). Receiver operating characteristic (ROC) analysis observed that the cut-off value of fatty liver diagnosis was 6.71% in using the quantitative US model; the sensitivity and specificity for fatty liver diagnosis were 94.15% and 96.30%, respectively. Variability analysis indicated that there was a relative high degree of consistency in the measurement of HFC with different operators or ultrasonic apparatus. Quantitative US measurement could be regarded as a simple, sensitive tool to accurately assess HFC. It provides a valid alternative to 1H-MRS as an easy, non-invasive option for the precise estimation of HFC in clinical practice.

Thermally Activated Jamming in Ultrasonic Powder Compaction

Herein, the role of thermal softening in ultrasonic powder compaction is assessed by comparing the densification behaviors of nominally pure Cu and a thermally stable CuTa alloy. These materials have similar thermal properties, but pure Cu softens at much lower temperatures than does the CuTa alloy. Using a specialized ultrasonic powder compaction setup, in situ measurements of relative density, sonotrode power consumption, and temperature are collected, which together provide a time‐dependent geometric hardening parameter that reflects the structure of the compact. The geometric hardening data for the pure Cu powder reveal three distinct stages of densification: an initial particle rearrangement stage; a jamming transition where strong junctions develop between particles; and a final stage characterized by compatible plastic deformation. By contrast, the geometric hardening data for the thermally stable CuTa powder show that it remains a weak fluidized granular medium, despite experiencing higher normal pressures, oscillation amplitudes, and temperatures. The contrasting behaviors of the Cu and the CuTa powders suggest that a thermally activated jamming transition drives interparticle junction growth and densification in ultrasonic powder compaction.

Ultrasonography Shows Age-related Changes and Related Factors in the Tongue and Suprahyoid Muscles

ObjectivesTo investigate age and other factors related to the deterioration of the muscles used for swallowing, including the tongue and suprahyoid muscles. DesignCross-sectional study. Setting and ParticipantsThis study included 146 participants: 47 younger adults (23 men and 24 women; age range 23-44 years) recruited from a dental hospital and 99 community-dwelling older adults (37 men and 62 women, age range 65-86 years). MethodsAge (<65 years or ≥65 years), body mass index (BMI), skeletal muscle mass index (SMI), and tooth loss (Eichner classification) were measured. The cross-sectional areas (CSAs) of the tongue, geniohyoid muscle, and anterior belly of the digastric muscle were measured using an ultrasonic diagnostic apparatus. The correlation between each muscle's CSA and strength was examined. Multiple regression analyses were performed separately for each sex using each muscle CSA as the dependent variable and age, BMI, SMI, and the Eichner classification as explanatory variables. ResultsOlder men had a significant positive correlation between tongue pressure and CSA (r = 0.35, P = .031). Jaw opening force was positively correlated with geniohyoid muscle CSA (r = 0.41, P = .001) in older women. In the multiple regression analysis, age, BMI, and SMI were significantly associated with tongue CSA in men. Age was significantly and inversely associated with suprahyoid muscle CSA in both men and women. No explanatory variables were significantly associated with geniohyoid muscle CSA except age. Conclusions and ImplicationsThe tongue increased in volume, and the suprahyoid muscles underwent atrophy with age. The study results suggest that interventions to prevent dysphagia associated with aging should be tailored toward specific muscles. Direct muscle training is required for the suprahyoid muscles, whereas the maintenance of tongue muscle mass and function, as well as training for the tongue, requires attention to ensure optimal nutritional status and whole-body skeletal muscle mass.

Cavitation erosion behavior of microwave-processed Ni–40Cr3C2 composite clads: A parametric investigation using ultrasonic apparatus

Cavitation erosion is the primary cause of material failure of the hydroelectric power plant components. The rapid development in the advanced surface engineering techniques has provided an effective treatment solution for cavitation erosion. One such novel method is microwave cladding. Hence, the Ni–40Cr3C2 composite clad was deposited on austenitic stainless steel (SS-316) using a microwave cladding process in the present study. The processing was carried out in a domestic microwave oven of 2.45 GHz frequency and 900 W power. The developed clad was thoroughly characterized for the metallurgical and mechanical properties related to its behavior as a successful cavitation erosion resistance material, like microstructure, crystal structure, porosity, microhardness, flexural strength, and fracture toughness. The results showed that the stripe-type and agglomerated carbides were present in the Ni–40Cr3C2 clad. The developed composite clad consists of various carbides (SiC, Ni3C, Cr3Ni2SiC, Cr7C3, and NiC) and intermetallic phases (Ni3Fe, Ni2Si, and Cr3Si). Microhardness, flexural strength, and fracture toughness of the microwave-processed clad were observed to be 605 ± 80 HV0.3, 813.23 ± 16.2 MPa, and 7.44 ± 0.2 MPa√m, respectively. The microwave-processed composite clad performance in terms of cavitation erosion resistance was determined using the ultrasonic apparatus (ASTM-G32-17). The cavitation experiments were carried out according to Taguchi L9 orthogonal array, taking into account three parameters: standoff distance, amplitude, and immersion depth. The developed composite clad exhibited significant resistance (mass loss 7.6 times lesser as compared to SS-316) to cavitation erosion. ANOVA results showed the standoff distance as the most important factor followed by amplitude and immersion depth. Least cavitation resistance was observed at a smaller standoff distance, higher amplitude, and lower immersion depth. Linear regression equations were obtained to establish the correlation between parameters and cumulative mass loss. The microwave clad specimens tested at optimized test parameters were damaged in the form of fractured intermetallic, extruded lips, pits, and craters.

Determination of acoustic nonlinearity parameters using thermal modulation of ultrasonic waves

This study presents a test method and its theoretical framework to determine the acoustic nonlinearity parameters (α, β, δ) of material using thermal modulation of ultrasonic waves. Temperature change-induced thermal strain excites the nonlinear response of the material and modulates the ultrasonic wave propagating in it. Experimental results showed a strong correlation between the relative wave velocity change and the temperature change. With a quadratic polynomial model, the acoustic nonlinearity parameters were obtained from the polynomial coefficients by curve fitting the experimental data. Their effects on thermal-induced velocity change were discussed. The parameters α, β, and δ govern the hysteretic gap, average slope, and curvature of the correlation curve, respectively. The proposed theory was validated on aluminum, steel, intact and damaged concrete samples. The obtained nonlinear parameters show reasonable agreement with values reported in the literature. Compared to other nonlinear acoustic methods using vibration or acoustic excitation, the thermal modulation method generates more uniform, slow changing, and larger strain field in the test sample. Employing the thermal effect as the driving force for nonlinearity instead of an undesired influencing factor, this method can measure the absolute values of α, β, and δ with good accuracy using a simple ultrasonic test setup.

Early Hydration and Setting Process of Fly Ash-blended Cement Paste under Different Curing Temperatures

A specially developed ultrasonic measurement apparatus (UMA) was used to in situ monitor the setting process of fly ash blended cement paste. Combined with the results of Vicat Needle tests, isothermal calorimetric measurement, XRD analysis, SEM morphology and compressive test, the influence of curing temperature (20, 40, 60, and 90 °C) and fly ash content (0,10%, 20% and 30%) on the setting and hydration process of fly ash blended cement paste was analyzed. The results show that setting and hardening process of fly ash blended cement paste at elevated temperature can be clearly identified into three stages including dormant stage, acceleration stage and deceleration stage. The increasing of curing temperature greatly accelerates the setting and hardening process. However, the content of fly ash does not have significant effect on the setting in condition of 90 °C. Besides, the initial and final setting time of cement paste is correspondent with the time of duration of dormant stage and the time of UPV value is 1 500 m/s (T1500), respectively. Thus, the UMA can be used to determine the initial and final setting time of cementitious material under different curing temperatures. The compressive test results indicate that the paste with 20% fly ash presents higher compressive strength than the plain paste at curing temperatures of 90 °C. Therefore, appropriate amount of fly ash is beneficial for concrete in the high temperature curing conditions.

Vehicle Lateral Wander Measures Using Ultrasonic Sensors

This paper evaluates the measurement of vehicle lateral wander using ultrasonic sensors. Measurements were made on different sections of the Costa Rican National Road Network. The recorded data allowed to determine the cumulative frequency distribution, lateral wander data and a confidence interval for the measurements. In some routes, where the sample size is greater than 70 vehicles, the distribution of the lateral wander data adjusted to a normal distribution. However, in several cases the data does not resemble a normal distribution curve, or other distributions reported in the literature. Finally, an Android app was developed to automate the data collection process using the ultrasonic sensor setup, simplifying the measurement process. From the cumulative frequency results, obtained with the ultrasonic sensors, it was determined that most vehicles travel between 50 and 150 cm from the edge of the road. In order to validate the data, the results obtained with the ultrasonic sensor setup were compared with the results obtained by image analysis of video recordings. These image analysis is possible due to pavement markings every five centimeters on the pavement from the lane edge. The results from video recordings and ultrasonic sensors show a high coefficient of correlation.

Morphology and mechanisms of cavitation damage on lamellar gray iron surfaces

Engine parts in contact with liquids may suffer cavitation erosion damage. Understanding its mechanisms in realistic operating environments is necessary for improvements in the service life and durability of materials for heavy-duty diesel engines. This work illustrates the cavitation erosion behavior of a cylinder liner material with a follow-up of detailed, high-magnification SEM images of damaged sites on the surface. The cylinder liner encloses the piston and combustion chamber in the engine of large trucks and its material of choice is usually a lamellar gray cast iron, its microstructure consisting of flake-shaped graphite, a pearlitic matrix and some steadite. Testing was carried out using an ultrasonic vibratory apparatus, and the liquid of choice was a commercial engine coolant composed of water, glycol and inhibitors. Based on observations of tested surfaces, a sequence of damage patterns is proposed as an explanation of the material’s cavitation erosion behavior. Initiation consists of: chipping at graphite cluster centers, graphite flake removal, pitting along graphite flakes and direct matrix pitting. Development consists of: evolution of chipped spots into matrix-damaging pits, radial pit expansion, pit merging and surface roughening. It can be concluded that presence and morphology of graphite are critical to the cavitation erosion behavior of LGI.

Association between myotonometric measurement of masseter muscle stiffness and maximum bite force in healthy elders.

Maximum bite force (MBF) is a common and useful index of masticatory function; it correlates with physical strength in elderly people. Palpation of stiffness in the masseter muscle during forceful biting has been considered to be associated with MBF. However, this assessment method relies on subjective judgments; no study has verified the relationship between MBF and quantitative measurements of masseter muscle stiffness (MMS). We aimed to verify the association between masseter muscle myotonometric assessment results and MBF. In total, 117 community-dwelling >65-year-old individuals from the Tokyo metropolitan area were assessed. MMS on the dominant side during forceful biting was measured with a MyotonPRO device. Masseter muscle thickness (MMT) during rest and forceful biting was measured with an ultrasonic diagnostic apparatus, and the difference in MMT (DMMT) between the rest and forceful biting conditions was determined. MBF data were obtained with a pressure-sensitive sheet and an associated device. To determine the independent variables affecting MBF and MMS, multivariate linear regression analyses with adjustments for age, sex and number of teeth were performed. The multivariate analysis revealed that MBF correlated with the number of teeth (β=.489, P<.001) and MMS (β=.259, P=.003) (R2 =.433). MMS correlated with MBF (β=.308, P=.003) and DMMT (β=.430, P<.001) (R2 =.326). Masseter muscle stiffness possibly reflects a force generated by the masseter muscle during forceful biting. Therefore, MMS is effective to assess tooth loss as well as an index of masseter muscle strength when evaluating MBF.

Deposition and cavitation erosion behavior of multimodal WC-10Co4Cr coatings sprayed by HVOF

Cavitation erosion is one of the major failure modes for engineering components operating in the marine environment. In this study, WC-10Co4Cr coatings with multi-scale WC particles were prepared on 304 stainless steel substrates by two high velocity oxygen fuel (HVOF) systems differentiated by the types of fuel. The splat formation process of the multimodal cermet particles was investigated, as well as coatings' porosity, microhardness, fracture toughness and electrochemical performance. In addition, the cavitation erosion resistance of the coatings was evaluated by ultrasonic vibratory apparatus in 3.5 wt% NaCl solution. The results show that the splats sprayed by high velocity oxygen liquid fuel (HVOLF) had a more disk-like shape, leading to much lower porosity and superior mechanical properties in the corresponding coating. The low porosity also significantly hindered the formation of cavitation sources and reduced the cavitation rate. More importantly, the synergistic effect of corrosion on cavitation erosion made the coating much more vulnerable in NaCl solution than in fresh water.

Picosecond ultrasonics with miniaturized semiconductor lasers

There is a great desire to extend ultrasonic techniques to the imaging and characterization of nanoobjects. This can be achieved by picosecond ultrasonics, where by using ultrafast lasers it is possible to generate and detect acoustic waves with frequencies up to terahertz and wavelengths down to nanometers. In our work we present a picosecond ultrasonics setup based on miniaturized mode-locked semiconductor lasers, whose performance allows us to obtain the necessary power, pulse duration and repetition rate. Using such a laser, we measure the ultrasonic echo signal with picosecond resolution in a 112 nm thick Al film deposited on a semiconductor substrate. We show that the obtained signal is as good as the signal obtained with a standard bulky mode-locked Ti-Sa laser. The experiments pave the way for designing integrated portable picosecond ultrasonic setups on the basis of miniaturized semiconductor lasers.

CD38 dictates cardiac damage through mitochondrial apoptotic pathway under hypoxic-ischemic conditions

Objective: To explore the mechanism of CD38-mediated cardiac damage under hypoxic-ischemic (H/I) conditions. Methods: Twenty CD38(-/-) male mice (8-week-old) and 20 wild-type (WT) male C57BL/6J mice (8-week-old) were randomly selected to construct the model of approximately 25% of the total body surface area (TBSA) burn injury. The cardiomyocytes (CMs) were separated from neonatal mice (1day) to construct the H/I injury model. Ad-CD38 adenovirus was transfected into CD38(-)/- primary CMs to callback CD38 expression. Animal experiments were grouped into WT-control group, CD38(-/-)-control group, WT-burn group, and CD38(-/-)-burn group (10 mice in each group). Primary CMs were divided into 6 groups: WT-normoxia group, CD38(-/-)-normoxia group, CD38(-/-)+Ad-CD38-normoxia group, WT-H/I group, CD38(-/-)-H/I group, CD38(-/-)+Ad-CD38-H/I group. The release of lactic dehydrogenase (LDH) from CMs and the cell viability were measured to estimate the level of myocardial injury. Ultrastructure of cardiomyocytes was examined by electron microscope. CD38 protein level and mitochondrial apoptosis-related proteins were detected by Western blot. Flow cytometry was used to detect mitochondrial reactive oxygen species (MitoSOX) of CMs under H/I condition. Cardiac function of mice was detected by ultrasonic apparatus. Results: (1) Animal experiments: The expression level of cardiac CD38 in WT-burn group was significantly higher than that in sham group (P<0.001). The heart function of CD38(-/-)-burn group was obviously better than WT-burn group [ejection fraction (EF)%: (84.70±2.31)% vs (76.10±2.96)%, shortening fraction (FS)%: (48.90±5.00)% vs (38.10±2.80)%] (both P<0.001). (2) Cell experiments: The expression level of cardiac CD38 in WT CMs under H/I condition was significantly higher than that in WT CMs under normoxia condition (P<0.05). The level of LDH, apoptotic cell and MitoSOX in CD38(-/-)-H/I group were fewer than WT-H/I group and CD38(-/-)+Ad-CD38(-)H/I group [(11.2±3.0)% vs (18.2±3.4)% and (17.6±4.0)%, (13.0±2.8)% vs (23.1±4.9)% and (23.3±6.0)%, (162±11)% vs (228±18)% and (220±18)%] (all P<0.001). The levels of cleaved-caspase3, Cytochrome-C in CD38(-/-)-H/I group were significantly lower than those in WT-H/I group and CD38(-/-)+Ad-CD38-H/I group (P<0.001). The cell viability in CD38(-/-)-H/I group was higher than that in WT-H/I group and CD38(-/-)+Ad-CD38-H/I group (0.355±0.043 vs 0.280±0.051 and 0.291±0.024) (all P<0.05). Electron microscopy results showed that structure of mitochondria in CD38(-/-)-H/I group was better than in WT-H/I group and CD38(-/-)+Ad-CD38-H/I group. Conclusion: Overexpression of CD38 contributes to cardiac damage by stimulating mitochondrial apoptotic pathway.

Association of aging and tooth loss with masseter muscle characteristics: an ultrasonographic study.

This study aimed to investigate the relationship between aging and tooth loss on masseter muscle quantity and quality. This cross-sectional study was conducted among 112 participants (in their 20s to 90s) who were independent in activities of daily living and were able to follow verbal commands. Exclusion criteria comprised participants with a lack of molar occlusal support, diseases that could affect muscle function, or temporomandibular disorder. Age, tooth loss, and weight were documented, and masseter muscle thickness (MMT) and masseter muscle echo intensity (MMEI) were measured using an ultrasonic diagnostic apparatus. A multiple regression analysis was used to determine the relationship between MMT, MMEI, aging, and tooth loss, among each sex. The significance level in the statistical analysis was p < 0.05. In males, aging was a significant explanatory variable for MMT (adjusted R2 = 0.27), while both aging and weight were significantly associated with MMEI (adjusted R2 = 0.54). In females, tooth loss and aging were significant explanatory variables for MMT (adjusted R2 = 0.36) and MMEI (adjusted R2 = 0.5), respectively. In both men and women, MMT and MMEI were highly correlated. Masseter muscles in males were more likely to be attenuated by aging than in females. The main attenuation factors were observed to differ between MMT and MMEI in women. In females, preservation of the natural dentition or prosthetic treatment may be effective for maintaining masseter muscle characteristics. In males, additional approaches, such as resistance exercise training, may be necessary.

Laboratory-scale characterization of saturated soil samples through ultrasonic techniques

The propagation of poroelastic waves in a soil specimen is dependent on the physical and mechanical properties of the soil. In the geotechnical practice, such properties are obtained through in-situ geotechnical testings or element soil testings in the laboratory. These methods require almost advanced equipment and both testing and sample preparation may be expensive and time-consuming. This paper aims to present an algorithm for a laboratory-scale ultrasonic non-destructive testing to determine the physical and mechanical properties of saturated soil samples based on the distribution of stress waves. The ultrasonic setup, in comparison to most conventional soil lab testing equipment, is low-cost and non-invasive such that it reduces the soil disturbance. For this purpose, a poro-elastodynamic forward solver and differential evolution global optimization algorithm were applied to characterize the porosity, density, and other mechanical properties for a soil column. The forward solver was developed based on a semi-analytical solution which does not require intensive computational efforts encountered in standard numerical techniques such as the finite element method. It was concluded that the proposed high-frequency ultrasonic technique characterizes effectively the saturated soil samples based on the output stress wave measured by the receiver. This development makes geotechnical investigations time-efficient and cost-effective, and as such more suited to applications in remote areas.

A novel UTMD system facilitating nucleic acid delivery into MDA-MB-231 cells.

Gene therapy is emerging as a promising method for the treatment of various diseases. The safe and efficient delivery of therapeutic nucleic acids is a gene therapy prerequisite. Ultrasound, particularly in combination with microbubbles composed of biocompatible materials such as lipid, PLGA and chitosan, is a novel non-viral tool for gene transportation. Under ultrasound irradiation, microbubbles explode and generate pores in the cell membrane. Hence, genes can enter cells more easily. In order to transfect nucleic acids into MDA-MB-231 cells in a low-cost and non-viral manner for further breast cancer gene therapy studies, we explored ultrasound targeted microbubble destruction (UTMD) technology and evaluated the efficiency and safety of the delivery of plasmid encoding enhanced green fluorescent protein (pEGFP) and a microRNA-34a (miR-34a) mimic by UTMD. Sonovitro ultrasonic apparatus was employed to generate ultrasonic field, which was developed by our group. Ultrasonic parameters, including acoustic intensity (AI), exposure time (ET) and duty cycle (DC), were optimized at 0.6 W/cm2 AI, 20 s ET and 20% DC, the cell viability was not obviously impaired. Under these conditions, the UTMD-mediated transfection efficiency of pEGFP was greater than 40%. In addition to plasmid DNA, an miR-34a mimic was also successfully introduced into the cytoplasm by UTMD and found to inhibit proliferation, induce apoptosis of MDA-MB-231 cells and regulate downstream molecules. The present study indicates that further in vivo UTMD-mediated gene therapy studies are warranted.

Long-term exposure to air pollution might increase prevalence of osteoporosis in Chinese rural population

ObjectivesThe associations of long-term exposure to air pollution with osteoporosis are rarely reported, especially in rural China. This study aimed to explore the association among rural Chinese population. MethodsA total of 8033 participants (18–79 years) derived from the Henan Rural Cohort Study (n = 39,259) were included in this cross-sectional study. Exposure to air pollutants was estimated using machine learning algorithms with satellite remote sensing, land use information, and meteorological data [including particulate matter with aerodynamic diameters ≤1.0 μm (PM1), ≤2.5 μm (PM2.5), and ≤10 μm (PM10), and nitrogen dioxide (NO2)]. The bone mineral density of each individual was measured by using ultrasonic bone density apparatus and osteoporosis was defined based on the T-score ≤ −2.5. Multiple logistic regression models were used to examine the association of air pollution and osteoporosis prevalence. ResultsWe observed that per 1 μg/m3 increase in PM1, PM2.5, PM10 and NO2 were associated with a 14.9%, 14.6%, 7.3%, and 16.5% elevated risk of osteoporosis. Compared with individuals in the first quartile, individuals in the fourth quartile had higher odds ratio (OR) of osteoporosis (P-trend < 0.001), the ORs (95% confidence interval) were 2.08 (1.72, 2.50) for PM1, 2.28 (1.90, 2.74) for PM2.5, 1.93 (1.60, 2.32) for PM10, and 2.02 (1.68, 2.41) for NO2. It was estimated that 20.29%–24.36% of osteoporosis cases could be attributable to air pollution in the rural population from China. ConclusionsLong-term exposure to air pollutants were positively associated with high-risk of osteoporosis, indicated that improving air quality may be beneficial to improve rural residents health.

Phytochemical evaluation and vasodilatory activity of O. elongatum, C. salviifolius and C. laurifolius

The high blood pressure is one of the main causes of death and cardiovascular diseases. Vasodilator medications are frequently used to treat arterial hypertension. The aim of this study was to evaluate vasodilator properties of three plants from North of Morocco then to quantify phenolic compounds and flavonoids in each plant extracts. The leaves of Origanum elongatum, Cistus salviifolius and Cistus laurifolius were extracted with hexane, methanol and ethyl acetate by ultrasonic apparatus. The total phenolic content, analyzed using Folin–Ciocalteu’s reagent, of the samples varied from 46.6 µg/100 mg to 153 µg/100 mg dry weight, expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 3.63 to 5.54 µg equivalents (RE)/mg dry weight. Under different plant growth regulators induce a vasodilator effect on Wistar rat mesenteric vascular bed pre-contracted with norepinephrine. for O.elongatum, the methanolic extracts at (PP = 50 mmHg) were found to be more active than the acetylcholine with a concentration of 10 -4 M taken as a reference (PP = 40 mmHg) and The vasodilator activity of methanolic extract of Cistus laurifolius at 100 μg/ml is the same as the reference (PP=40 mmHg). the vasodilator activity found in the three plants studied is due to their antioxidant power.

Understanding the Effect of Resonant Frequency Using Ultrasonic-Assisted Measurement in Gas Fuel System for Natural Gas Vehicle

This work is the experimental study to use the ultrasonic sensor which can seek the optimum sensitivity of pure methane gas used in natural gas vehicle (NGV). This research is to experimentally analyze the acoustic characteristics using an impedance analyzer and three different thicknesses of ultrasonic matching layer (UML). The experiment is composed of 7.0, 7.5, and 8.0 mm of matching layer thickness, 30, 60, 90, and 120 cm of sensor gap in atmospheric air, 20 and 40 cm of sensor gaps between transmission and reception, pure methane of used fuel, 0 ∼ 45 % of mixture gas (CH4), 350 and 400 V of input voltage strength, and 295 K for room temperature. The experiment method includes the sensor concept and structure, theory of ultrasonic energy transfer, signal processing, and experimental setups and conditions. As a result, the sensor sensitivity of ML 7.5 mm is well-measured by stages in entire ratios of an air-methane mixture. Namely, it can be noticed that sensitivity of ML 7.5 mm has the most appropriate effect in the measurement of gas fuel comparing with other sensors. Consequently, the sensitivity characteristics in an air-methane mixture ratio and pure gas space (PGS) have a relation of an inverse proportion. Furthermore, the accuracy of methane gas in high-pressure is higher than low-pressure condition because ultrasound is advantageous in high density.

ВЛИЯНИЕ КОРРОЗИОННОГО ФАКТОРА НА КАВИТАЦИОННУЮ ИЗНОСОСТОЙКОСТЬ СПЛАВОВ ДЛЯ ГРЕБНЫХ ВИНТОВ

The resistance of the stainless steel 08H14NDL, the bronze BrA8Mts11Zh3N2L and the brass LTs40Mts3Zh to cavitation erosion was investigated in fresh water and artificial sea water. The tests were carried out on an ultrasonic vibratory apparatus. The horn of the vibratory device resonated at approximately 22 kHz, a peak-to-peak amplitude being changed from 24 to 54 μm. The distance between the horn butt-end and the specimen surface equaled 0.5 mm. It was shown, that the increase in the amplitude of vibration leads to the decrease in the difference between the cavitation wear in fresh water and the sea water. It was demonstrated that under the cavitation attack of high intensity the wear of the brass in the sea water can be essentially lower than the one obtained in the fresh water. The demonstrated paradox may be attributed to the peculiarities of the cavitation impact on the ultrasonic vibratory apparatus combined with the plasticizing action of the aggressive liquid. The ultrasonic frequency of the shock waves action on the surface increases dislocations mobility, whereas the stripping the surface layers with sea water alleviates the discharge of the dislocations on the surface: the chemomechanical effect takes place.

Gender-specific prevalence and influencing factors of osteopenia and osteoporosis in Chinese rural population: the Henan Rural Cohort Study

ObjectiveThe aims of this study were to describe distributions of the prevalence of osteopenia and osteoporosis and identify the potential risk factors by gender in a Chinese rural population.DesignA cross-sectional...