Long-term prognosis in patients with thymoma combined with myasthenia gravis: a propensity score-matching analysis.

Introduction: We aimed to assess the impact of myasthenia gravis (MG) on the long-term prognosis in patients with thymoma after surgery and identify related prognostic factors or predictors. Methods: This retrospective observational study included 509 patients with thymoma (thymoma combined with MG [MG group] and thymoma alone [non-MG group]). Propensity score matching was performed to obtain comparable subsets of 96 patients in each group. A comparative analysis was conducted on various parameters. Results: Before matching, the 10-year survival and recurrence-free survival rates in both groups were 93.8 and 98.4%, and 85.9 and 93.4%, respectively, with no statistically significant difference observed in the survival curves between the groups (p > 0.05). After propensity score matching, 96 matched pairs of patients from both groups were created. The 10-year survival and recurrence-free survival rates in these matched pairs were 96.9 and 97.7%, and 86.9 and 91.1%, respectively, with no statistical significance in the survival curves between the groups (p > 0.05). Univariate analysis of patients with thymoma postoperatively revealed that the World Health Organization histopathological classification, Masaoka-Koga stage, Tumor Node Metastasis stage, resection status, and postoperative adjuvant therapy were potentially associated with tumor recurrence after thymoma surgery. Multivariate analysis demonstrated that the Masaoka-Koga stage and postoperative adjuvant therapy independently predicted the risk of recurrence in patients with thymoma after surgery. Conclusion: There was no difference in prognosis in patients with thymoma with or without MG. The Masaoka-Koga stage has emerged as an independent prognostic factor affecting recurrence-free survival in patients with thymoma, while postoperative adjuvant therapy represents a poor prognostic factor.

Design and development of a novel piezoelectric caudal fin-like underwater thruster with a single vibration mode.

The flapping-motion of the caudal fin allows the fish to swim with high efficiency and mobility, particularly in terms of persistence, propulsion, and acceleration. This has led to theoretical and practical research on the development of robotic caudal fin thrusters that offer similar properties and performance. However, the current caudal fin thrusters are driven by electromagnetic motors, which require a transmission system that makes them difficult to miniaturize, and need protection against water intrusion. To address these issues, this paper proposes a novel piezoelectric caudal fin thruster with a fully open structure that has no chambers in any of its parts. The converse, piezoelectric effect and direct friction drive principle are used to make a rotation unit for the piezoelectric actuator drive and achieve a reciprocating motion that makes the caudal fin flap. The proposed piezoelectric caudal fin thruster has an open and simple structure. It has a weight of 30 g, a length of 89 mm, and a thrust of 0.07 N. It is easy to miniaturize and is lighter, smaller, and more efficient than previously reported caudal fin thrusters that were based on ionic polymer-metal composites and shape memory alloys. Experimental results verified the effectiveness of the proposed design, which can be easily scaled up or down in size depending on the operating situation.

Ultrasonic manipulation for precise positioning and equidistant transfer of inertial confinement fusion microspheres.

As the thermonuclear fuel container, the inertial confinement fusion (ICF) microspheres must be detected before the ICF experiment to maximize the profits of fusion reactions. However, in the current detection method, the ICF microsphere is in direct contact with the measurement platform, resulting in the ICF microsphere surface being easily damaged during the detection process. In this paper, an ultrasonic manipulation method is proposed, realizing non-destructive, high-precision, and high-efficient manipulation of the ICF microsphere by switching the two acoustic fields produced in the liquid. When detecting the ICF microsphere, the first acoustic field (1st AF) accurately traps the microsphere in the acoustic field center to achieve its precise positioning. And when the ICF microsphere is failed to pass the detection, it is transferred out of the microscope measurement area by switching to the second acoustic field (2nd AF). Two solid vibration modes, their corresponding acoustic fields, and the two acoustic streaming fields are first computed by the finite element method. Then, the manipulation experiments indicated that the ICF microspheres can be first driven to the center of the 1st AF and then be positioned here with a minimum positional fluctuation of 1.1 µm. By changing to the 2nd AF, the positioned microsphere can be transferred nearly 11 mm to the nearest antinode from the acoustic field center. Finally, based on the proposed ultrasonic manipulation method, the detection experiments of the ICF microsphere were carried out, illustrating that the positioning of the 1st AF meets the requirements of the morphology detection and the radius measurement of the ICF microsphere. The proposed method holds the advantages of non-destructive, high-precision, simple control scheme and meets the practical application needs of the microsphere fixed-point detection, presenting the potential promise for the field of microsphere detection.

Study on a novel omnidirectional ultrasonic cavitation removal system for Microcystis aeruginosa.

Microcystis aeruginosa, as a typical alga, produces microcystin with strong liver toxicity, seriously endangering the liver health of human and animals. Inhibiting the bloom of the Microcystis aeruginosa in lakes becomes a significant and meaningful work. Ultrasonic cavitation is currently considered to be the most environmentally friendly and effective method for the removal of Microcystis aeruginosa. However, the commercialized ultrasonic algae removal systems require multi-Langevin transducers to achieve omnidirectional ultrasonic irradiation due to the single irradiation direction of the Langevin transducer, resulting in the complex design and high energy consumption. To achieve a low-cost, simple structure, and high-efficiency algae removal system, a novel omnidirectional ultrasonic cavitation removal system for Microcystis aeruginosa is proposed. The proposed system is major composed of a novel omnidirectional ultrasonic transducer, which generates the omnidirectional ultrasonic irradiation by its shaking-head motion coupled by two orthogonal bending vibration modes. Modal simulation, sound field simulation, and cavitation bubble radius simulation are first carried out to optimize the geometric sizes of the proposed transducer and verify the correctness of the omnidirectional ultrasonic irradiation principle. Then the vibration characteristics of the transducer prototype are measured by vibration tests and impedance tests. Finally, the feasibility and effectiveness of the proposed omnidirectional ultrasonic removal system for Microcystis aeruginosa are evaluated through the algae removal experiments. The experimental results exhibit that the algal cells damaged by ultrasonic irradiation from the proposed system do not have the ability to self-repair. In addition, the algal removal rates reached 55.41% and 72.97% after 30 min of ultrasonic treatment when the corresponding ultrasonic densities are 0.014 W/mL and 0.021 W/mL, respectively. The proposed omnidirectional ultrasonic algae removal system significantly simplifies the configuration and reduces energy consumption, presenting the potential promise of algae removal and environmental protection.

Transfer matrix modeling on a longitudinal-bending coupled piezoelectric transducer with single-phase excitation: Analysis and verification.

Surface-bonded type piezoelectric transducers have the advantages of simple structure, easy miniaturization, and flexible design and have been widely employed as the stator of ultrasonic motors. In order to simplify the control system, a surface-bonded type single-phase excited piezoelectric transducer operating in the longitudinal-bending coupling vibration is proposed, modeled, and validated in this study. Using the asymmetrical excitation effect, the longitudinal-bending coupled vibration is generated in the proposed piezoelectric transducer only applied with a single-phase electrical signal, leading to the production of the elliptical motion at its driving tip. The proposed transducer holds the advantages of compact structure, simple control system, and low manufacturing costs. The transfer matrix method, which is an efficient and fast semi-analytic computation solution, is employed to develop a dynamic model for the proposed transducer in this study in order to provide a general modeling method for surface-bonded type piezoelectric transducers operating with the longitudinal-bending coupled vibration. A novel longitudinal-bending coupled vibration transfer matrix is created first for surface-bonded type piezoelectric composite element. Then, a general semi-analytical electromechanical coupling model is developed to analyze dynamic behaviors of the proposed piezoelectric transducer. Finally, experimental validation is carried out on the prototype of the proposed piezoelectric transducer and compared with the calculation results using the developed transfer matrix model. Experimental results matched well with the calculation results, which confirmed the correctness of the transducer design and verified the feasibility of the developed transfer matrix model. The proposed piezoelectric transducer presents the potential application for linear ultrasonic motors.

A novel underwater piezoelectric thruster with one single resonance mode.

In this paper, a novel underwater piezoelectric thruster with one single resonance mode is proposed. The piezoelectric thruster consists of one piezoelectric transducer and two propellers. In order to relieve the bulky problem of underwater thrusters using a DC motor as the power source, the piezoelectric thruster adopts a full-open structure; thus, the piezoelectric thruster does not need additional sealing elements. Compared with underwater thrusters using a DC motor, the piezoelectric thruster has advantages of simple structure and small volume. By using piezoelectric ceramics, the first-order longitudinal mode of the transducer is excited to drive two propellers rotating in opposite directions. A prototype of the piezoelectric thruster is fabricated and experimentally investigated; it is 22 g in weight and 124 mm in length. The experimental results indicate that when the excitation voltage of the piezoelectric transducer is 300 Vpp, the rotational speed of the positive propeller is up to 1267 rpm and the stall torque is 1.71 mN m; meanwhile, the rotation speed of the negative propeller is up to 1203 rpm, and the stall torque is 1.75 mN m. When the piezoelectric thruster is working underwater, the average forward speed reaches 106.01 mm/s at 400 Vpp.

A novel ring-beam piezoelectric actuator for small-size and high-precision manipulator.

A new type of ring (joint)-beam (arm) element based on piezoelectric actuator is designed in this paper. By using piezoelectric ceramics, the vibration modes of two parallel beams are excited and coupled to form in-plane waves on the ring. As the piezoelectric actuator has the dual effect of acting as the power source and the main body structure of the arm joint, compared with the rotating joint using DC motor as the power source, the actuator does not need additional space to install the motor, which makes joint mechanism have the advantages of simple structure and small volume. Furthermore, the micro-displacement control of joints can be achieved by the characteristics of fast response and power self-locking based on the friction driving principle. A two-degree-of-freedom three-arm prototype of the joint mechanism is designed to obtain the parameters of the piezoelectric actuator and carry out related experiments. The prototype of the mechanism is 72 g in weight and 105 mm in length, and the maximum rotation angle of each joint is 210 deg. The experimental results indicate that, when driving frequency is 58.6 kHz and the driving voltage is 300 Vpp, the angular speed of the prototype reaches 45.9 deg/s, the resolution is 0.015 deg and the startup and shutdown response time are 35 ms and 21 ms, respectively. Due to its simple and compact structure, the manipulator have strong growth potential for meeting the requirements of wet hyperbaric environment. The characteristics of fast response time and high resolution enable good mobility and high precision.

An articulated finger driven by single-mode piezoelectric actuator for compact and high-precision robot hand.

In this paper, a novel finger driven by single-mode piezoelectric actuator for a compact and high-precision robot hand is proposed. Three piezoelectric actuators are articulated by two sets of connecting elements to form the finger. The finger utilizes a single model of the piezoelectric actuator to generate friction force to drive the joint. Without the difficulty to adjust for the coincidence of modal frequencies, the design of the piezoelectric actuator has fewer restrictions on size and structure; thus, the finger has a compact structure. The bidirectional motion of the joint is achieved by changing the temporal phase difference of two excitation signals applied on the two adjacent piezoelectric actuators. In addition, due to the characteristics of piezoelectric drive, such as power cut self-locking and quick response, the finger has a high resolution to realize micromanipulation for high precise movement. In our design, the first order longitudinal vibration mode of the piezoelectric actuator is used to generate the friction force. By using a finite element model, the geometric parameters of the piezoelectric actuator are obtained. A prototype of the finger is fabricated and experimentally investigated, the size (111 × 10 × 10 mm) is approximately 1.5 times that of a human middle finger, and the weight is 0.11 kg. The experimental results indicate that the angular speed of the prototype reaches 6.6 rad/s, the resolution is 20 mrad, and the startup and shutdown response times are 26 ms and 7 ms under a voltage of 400 Vpp, respectively. The fingertip force is 0.27 N under a voltage of 400 Vpp. The proposed finger has a compact size and simple structure with a high resolution (20 mrad).

A novel robotic arm driven by sandwich piezoelectric transducers.

In this work, a novel robotic arm driven by sandwich piezoelectric transducers is proposed. The proposed robotic arm is composed of three arms and four joints. Each arm consists of a sandwich piezoelectric transducer and an H-shaped hollow frame. The sandwich piezoelectric transducer utilizes frictional force to drive the joints on its both sides to rotate simultaneously. The joint between two arms can be driven to rotate in two perpendicular directions by two sandwich piezoelectric transducers. The rotation of joints results in the arm motion. Utilizing the finite element method, the optimized geometrical parameters of the sandwiched piezoelectric transducer are obtained, and the operating principle is demonstrated. A prototype of the robotic arm is also fabricated and assembled, it is 573 g in weight and 412 mm in length, and the maximum rotation angle of each joint is 160°. The mechanical characteristics of the robotic arm prototype are investigated by experiments. The results indicate that, when the excitation frequency of one sandwich piezoelectric transducer is 37.4 kHz, the arms on its two sides rotate in opposite directions with an average rotational velocity of 320 deg/s at 330 Vpp, a resolution of 100 µrad at 230 Vpp, and a startup and shutdown response time of 40 ms and 30 ms at 230 Vpp, respectively.

A novel ultrasonic surface machining tool utilizing elastic traveling waves.

With the rapid development of modern industrial technology and high performance technology products, ultra-precision machining technology becomes increasingly important. However, joint clearance of kinematic pairs, lack of feeding accuracy and overlarge contact stress still limit the further improvement of ultra-precision machining technology. In this study, a novel surface machining method utilizing structural elastic waves was proposed, and a machining tool using the piezoelectric actuating principle was presented for verifying the proposed method. Two vibration modes with a phase shift of π/2 in both space and time domains are exited simultaneously in the elliptical motion of points on the structural surface. By means of adjusting driving signal parameters, such as frequency, voltage amplitude and phase shift, different machining performances could be achieved. The configuration and working vibration modes of the proposed machining tool were firstly calculated by the finite element method, and then the optimal working frequency of the machining tool prototype was determined by vibration characteristic experiments. At last, machining characteristic experiments were conducted to validate the proposed machining method. Experimental results showed that the minimum working contact force between the machining tool and workpiece was 1N, and the chipped depth of 1.93µm was achieved at the same contact force after machining for 5min. And at the conditions of the contact force of 6N, two driving voltages of 400Vpp with a phase shift of π/2, and machining time of 5min, the prototype could achieve to machine the workpiece most efficiently and the roughness of the machined workpiece surface could be reached approximating 0.20µm. In conclusion, this proposed machining method could achieve a good quality machined surface with low residual stress and little damage by applying low contact force. Furthermore, it also had the advantage of no joint clearance error due to no kinematic pair in the structure, which improves the machining precision.

Role of Contrast-Enhanced Ultrasound in Diagnosis of Thyroid Nodules in Acoustic Radiation Force Impulse "Gray Zone".

The aim of this study was to evaluate the clinical value of contrast-enhanced ultrasound (CEUS) in the diagnosis of thyroid nodules in the acoustic radiation force impulse (ARFI) "gray zone" (the shear wave velocity is in the range 2.5-3 m/s). ARFI was performed before thyroidectomy in 70 patients with 200 thyroid nodules, and then CEUS was performed in 40 thyroid nodules in the "gray zone." The accuracy of ARFI for the 200 thyroid nodules was 82% (164/200). The accuracy of ARFI for the 40 "gray zone" thyroid nodules was 70% (28/40), whereas the accuracy of CEUS for the "gray zone" thyroid nodules was 90% (36/40). There was a significant difference in accuracy (p < 0.05). CEUS has better accuracy for thyroid nodules in the ARFI "gray zone." CEUS supplemented ARFI in differential diagnosis of benign and malignant thyroid nodules.

A novel modal-independent ultrasonic motor with dual stator.

In this paper, a novel modal-independent ultrasonic motor with dual stator is proposed, in order to relieve the difficulty of adjustment for coincidence of modal frequencies of a stator for multi-modal coupling type ultrasonic motor (USM). It consists of two stators (an upper stator and a lower stator) and a rotor. The stators are excited the 3rd longitudinal vibration mode, by arranging the location of rotor and two stators, the rotor can realize rotary motion by friction effect with the stators. The rotor is mounted between the maximum deformation location of the upper stator and the nodal line of the lower stator. Since two stators are the same and are excited the same vibration mode, the modal-independent USM can adjust the coincidence of modal frequencies conveniently. Furthermore, the stator of the modal-independent USM has the characteristics of simple structure, which promised advantages of easy designing, manufacturing, miniaturizing and suitable for the mass production of USM. Modal test shows the disparity between the modal frequencies of the stators is 0.78%. Mechanical characteristic test shows the rotary speed of the USM is 75 revolutions per minute (clockwise) and 65.8 revolutions per minute (anti-clockwise) at the voltage of 400Vp-p. And at the same voltage, the maximum torque is 8.4N·mm. The resolution of the modal-independent USM can up to 0.34mrad at the applied voltage of 400Vp-p.

A novel sandwich-type traveling wave piezoelectric tracked mobile system.

In this paper, a novel sandwich-type traveling wave piezoelectric tracked mobile system was proposed, designed, fabricated and experimentally investigated. The proposed system exhibits the advantages of simple structure, high mechanical integration, lack of electromagnetic interference, and lack of lubrication requirement, and hence shows potential application to robotic rovers for planetary exploration. The tracked mobile system is comprised of a sandwich actuating mechanism and a metal track. The actuating mechanism includes a sandwich piezoelectric transducer and two annular parts symmetrically placed at either end of the transducer, while the metal track is tensioned along the outer surfaces of the annular parts. Traveling waves with the same rotational direction are generated in the two annular parts, producing the microscopic elliptical motions of the surface particles on the annular parts. In this situation, if the pre-load is applied properly, the metal track can be driven by friction force to achieve bidirectional movement. At first, the finite element method was adopted to conduct the modal analysis and harmonic response analysis of the actuating mechanism, and the vibration characteristics were measured to confirm the operating principle. Then the optimal driving frequency of the system prototype, namely 35.1kHz, was measured by frequency sensitivity experiments. At last, the mechanical motion characteristics of the prototype were investigated experimentally. The results show that the average motion speeds of the prototype in dual directions were as 72mm/s and 61.5mm/s under the excitation voltage of 500VRMS, respectively. The optimal loading weights of the prototype in bi-directions were 0.32kg and 0.24kg with a maximum speed of 59.5mm/s and 61.67mm/s at the driving voltage of 300VRMS, respectively.

Superb Microvascular Imaging-A new vascular detecting ultrasonographic technique for avascular breast masses: A preliminary study.

OBJECTIVES: Superb Microvascular Imaging (SMI) is a new vascular imaging technique detecting a slower velocity that color Doppler flow image (CDFI) cannot. The aim of this study is to evaluate the clinical value of SMI for detecting penetrating vessels (PVs) in avascular breast lesions. METHODS: Seventy-nine patients with 82 breast lesions were examined by conventional ultrasound and diagnosed as Breast Imaging Reporting and Data System (BI-RADS) level 3 or 4. CDFI detected no PVs; subsequently, Power Doppler (PD), Advanced Dynamic Flow (ADF), and SMI were performed to detect any PVs in the breast lesions. RESULTS: Compared with PD or ADF, SMI revealed significantly (P<0.01) higher median numbers of PVs in breast lesions. The area under the receiver operating characteristic curve was 0.914 before the corrected classification versus 0.947 after the corrected classification (P<0.05). CONCLUSIONS: SMI was helpful in the differential diagnosis of benign versus malignant in avascular breast lesions, especially those in BI-RADS category 4.

Acoustic radiation force impulse imaging (ARFI) for differentiation of benign and malignant thyroid nodules--A meta-analysis.

OBJECTIVES: Work-up of thyroid nodules remains challenging. Acoustic radiation force impulse imaging (ARFI)-generated shear wave elastography, which can measure quantitatively tissue stiffness (virtual touch tissue quantification) is used as a complement to conventional sonography for improving the diagnosis of thyroid nodules. This meta-analysis was performed to expand on a previous meta-analysis to assess the diagnostic power of ARFI in differentiating benign and malignant thyroid nodules. METHODS: The MEDLINE, PubMed, SpringerLink databases up to December 31, 2014, were searched. The pooled sensitivity, specificity, and summary receiver operating characteristic curve were obtained from individual studies with a random effects model. RESULTS: Sixteen studies that included a total of 2436 nodules in 2147 patients for ARFI studies were analyzed. The overall mean sensitivity and specificity of ARFI for differentiation of thyroid nodules were 0.80 (95% confidence interval [CI], 0.73-0.87) and 0.85 (95% CI, 0.80-0.90), respectively. A significant heterogeneity was found for both sensitivity and specificity of the different studies (P<0.001). The area under the curve for the ARFI was 0.91. CONCLUSIONS: ARFI has high sensitivity and specificity for identification of thyroid. This technique might be useful to select patients with thyroid nodules for surgery.

Expression level of miR-155 in peripheral blood.

OBJECTIVE: To investigate the relationship between the expression level of miR-155 and the severity of coronary lesion, and explore the action mechanism. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated form blood simple from patients with acute myocardial infarction (AMI), unstable angina (UAP), stable angina (SAP) and chest pain syndrome (CPS). RT-PCR was performed to analysis the expression level of miR-155 in peripheral blood mononuclear cells, plasma and RAW264.7 macrophagocyte. MTT was used to analyze the cell viability of OxLDL treated RAW264.7 macrophagocyte. RESULTS: The expression level of miR-155 in blood sample from coronary heart disease patients was much lower than in the blood sample of non-coronary heart disease (P<0.05). The level of miR-155 in PBMCs was much higher in the blood sample from CPS group than the other three group, and the level of miR-155 in plasma was higher in the CPS group than in the UAP and the AMI group, the difference was statistically significant (P<0.05). The expression level of miR-155 in PBMCs is positively associated with the level in the plasma (r=0.861, P=0.000). OxLDL can induce the expression of miR-155 in RAW264.7 macrophagocyte, decrease the cell viability of RAW264.7 macrophagocyte, and with the concentration and the treatment time of OxLDL increased, the effort become more obvious. The inhibition effort of OxLDL to RAW264.7 macrophagocyte with high miR-155 expression is much lower than the control group, and it is statistically significant after treated for 12, 24 and 48 h. CONCLUSIONS: miR-155 plays a protective role in the progression of atherosclerosis, and it may be achieved by reducing the apoptosis effort of OxLDL to RAW264.7 macrophagocyte.

The origin of high activity but low CO(2) selectivity on binary PtSn in the direct ethanol fuel cell.

The most active binary PtSn catalyst for direct ethanol fuel cell applications has been studied at 20 °C and 60 °C, using variable temperature electrochemical in situ FTIR. In comparison with Pt, binary PtSn inhibits ethanol dissociation to CO(a), but promotes partial oxidation to acetaldehyde and acetic acid. Increasing the temperature from 20 °C to 60 °C facilitates both ethanol dissociation to CO(a) and then further oxidation to CO2, leading to an increased selectivity towards CO2; however, acetaldehyde and acetic acid are still the main products. Potential-dependent phase diagrams for surface oxidants of OH(a) formation on Pt(111), Pt(211) and Sn modified Pt(111) and Pt(211) surfaces have been determined using density functional theory (DFT) calculations. It is shown that Sn promotes the formation of OH(a) with a lower onset potential on the Pt(111) surface, whereas an increase in the onset potential is found upon modification of the (211) surface. In addition, Sn inhibits the Pt(211) step edge with respect to ethanol C-C bond breaking compared with that found on the pure Pt, which reduces the formation of CO(a). Sn was also found to facilitate ethanol dehydrogenation and partial oxidation to acetaldehyde and acetic acid which, combined with the more facile OH(a) formation on the Pt(111) surface, gives us a clear understanding of the experimentally determined results. This combined electrochemical in situ FTIR and DFT study provides, for the first time, an insight into the long-term puzzling features of the high activity but low CO2 production found on binary PtSn ethanol fuel cell catalysts.

Assessment of left ventricular diastolic dysfunction based on the intraventricular velocity difference by vector flow mapping.

OBJECTIVES: The diastolic intraventricular velocity difference represents diastolic function of the left ventricle (LV). Here we analyzed the LV diastolic intraventricular velocity difference in patients with impaired LV function based on the ventricular flow rate profile by vector flow mapping. METHODS: Patients with LV diastolic dysfunction were divided into 2 groups: chronic heart failure with restricted filling (group 1; n = 27) and hypertension with abnormal relaxation (group 2; n = 34). Healthy participants were identified as controls (group 3; n = 22). Left ventricular inflow color Doppler findings were analyzed by the vector profile model with the vector flow mapping technology offline. The flow velocity rates at the base and apex of the LV were measured from vector profiles with the vector flow mapping technology. The diastolic intraventricular velocity difference was calculated from flow velocity rates. RESULTS: The diastolic intraventricular velocity difference calculated from vector flow mapping was significantly lower in both groups with LV diastolic dysfunction than the control group (mean ± SD, 79.95 ± 9.88 cm/s in controls versus 40.35 ± 6.80 cm/s in group 1 and 48.50 ± 6.03 cm/s in group 2; P < .001 for both). The diastolic intraventricular velocity difference had a significant association with the ejection fraction (P = .0002) and deceleration time (P = .0306). The peak atrial contraction velocity was negatively related to the diastolic intraventricular velocity difference (P = .0003). CONCLUSIONS: The diastolic intraventricular velocity difference derived from the LV velocity rate by the vector profile model on vector flow mapping can be potentially used for quantitative assessment of LV diastolic function. Vector flow mapping proved to be clinically practical for reflecting LV diastolic dysfunction in pathologic states.

WC@meso-Pt core-shell nanostructures for fuel cells.

We developed a facile method to synthesize core-shell WC@meso-Pt nanocatalysts by carburizing ammonium tungstate and copper nitrate via gas-solid reactions, followed by a Pt replacement reaction. The mesoporous nanocomposite displays higher activity and stability towards methanol electrooxidation than commercial Pt/C catalysts.