Wireless capsule endoscopy has opened a new era by enabling remote diagnostic assessment of the gastrointestinal tract in a painless procedure. Video capsule endoscopy is currently commercially available worldwide. However, it is limited to visualization of superficial tissue. Ultrasound (US) imaging is a complementary solution as it is capable of acquiring transmural information from the tissue wall. This paper presents a mechanical scanning device incorporating a high-frequency transducer specifically as a proof of concept for US capsule endoscopy (USCE), providing information that may usefully assist future research. A rotary solenoid-coil-based motor was employed to rotate the US transducer with sectional electronic control. A set of gears was used to convert the sectional rotation to circular rotation. A single-element focused US transducer with 39-MHz center frequency was used for high-resolution US imaging, connected to an imaging platform for pulse generation and image processing. Key parameters of US imaging for USCE applications were evaluated. Wire phantom imaging and tissue phantom imaging have been conducted to evaluate the performance of the proposed method. A porcine small intestine specimen was also used for imaging evaluation in vitro. Test results demonstrate that the proposed device and rotation mechanism are able to offer good image resolution ( [Formula: see text]) of the lumen wall, and they, therefore, offer a viable basis for the fabrication of a USCE device.

Advances in methodologies and tools often lead to new insights into cardiovascular diseases. Intravascular ultrasound (IVUS) is a well-established diagnostic method that provides high-resolution images of the vessel wall and atherosclerotic plaques. High-frequency (>50 MHz) ultrasound enables the spatial resolution of IVUS to approach that of optical imaging methods. However, the penetration depth decreases when using higher imaging frequencies due to the greater acoustic attenuation. An imaging method that improves the penetration depth of high-resolution IVUS would, therefore, be of major clinical importance. Modulated excitation imaging is known to allow ultrasound waves to penetrate further. This paper presents an ultrasound system specifically for modulated-excitation-based IVUS imaging. The system incorporates a high-voltage waveform generator and an image processing board that are optimized for IVUS applications. In addition, a miniaturized ultrasound transducer has been constructed using a Pb(MgNb)O-PbTiO single crystal to improve the ultrasound characteristics. The results show that the proposed system was able to provide increases of 86.7% in penetration depth and 9.6 dB in the signal-to-noise ratio for 60 MHz IVUS. In vitro tissue samples were also investigated to demonstrate the performance of the system.

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Asian Orogenic Belt (CAOB). Early Mesozoic igneous rocks in this area can place constraints on the crustal growth mechanism in the Northeastern China. This paper reports a suite of Late Triassic high-Mg diorites and mafic dikes from the southern Lesser Xing'an-Zhangguangcai Range. The mafic dikes have younger zircon U-Pb ages of 195 ± 2 Ma. They display intermediate SiO 2 (50.58% to 58.20%) and high Na 2 O/K 2 O ratios of 1.90 to 3.20, low A/CNK ratios of 0.75 to 0.84, low ( 87 Sr/ 86 Sr) i ratios of 0.7045 to 0.7046, and high ε Nd (t) values of +3.1 to +3.5. Most zircons in the mafic dikes exhibit positive ε Hf (t) values from +8.6 to +16.0, with single-stage Hf model ages ranging from 0.2 to 0.5 Ga in combination with their enrichment in LREE and LILEs and depletion in HFSEs. They are considered to be formed by melting of metasomatized subarc lithosphere mantle. The diorite and quartz diorite have older zircon U-Pb ages of 200 ± 3 and 202 ± 2 Ma, respectively. They have SiO 2 = 54.45%to 61.18%, Al 2 O 3 = 17.16% to 19.10%, TiO 2 = 0.74% to 1.13%, and Mg # = 46.6 to 49.5, and they also display moderately depleted Sr-Nd (ε Nd (t) = +2.3 to +4.3) and zircon Lu-Hf (ε Hf (t) = +8.6 to +16.0) isotopic compositions. These features suggest that they were formed by melting of juvenile arc crust in active continental margin.Considering the occurrence of the contemporaneous and latter igneous rocks in the Zhangguangcai Range, we argue that the diorite, quartz diorite, and mafic dikes from the Lengshan area were also related to the westward subduction of Palaeo-Pacific Plate (Izanagi Plate) beneath the Eurasian Plate. The strike-like fault along the eastern margin of the Songneng-Zhuangguangcai Block may play an important role in the genesis of diorite melt.