Transcranial volumetric imaging using a conformal ultrasound patch.

Accurate and continuous monitoring of cerebral blood flow is valuable for clinical neurocritical care and fundamental neurovascular research. Transcranial Doppler (TCD) ultrasonography is a widely used non-invasive method for evaluating cerebral blood flow1, but the conventional rigid design severely limits the measurement accuracy of the complex three-dimensional (3D) vascular networks and the practicality for prolonged recording2. Here we report a conformal ultrasound patch for hands-free volumetric imaging and continuous monitoring of cerebral blood flow. The 2 MHz ultrasound waves reduce the attenuation and phase aberration caused by the skull, and the copper mesh shielding layer provides conformal contact to the skin while improving the signal-to-noise ratio by 5 dB. Ultrafast ultrasound imaging based on diverging waves can accurately render the circle of Willis in 3D and minimize human errors during examinations. Focused ultrasound waves allow the recording of blood flow spectra at selected locations continuously. The high accuracy of the conformal ultrasound patch was confirmed in comparison with a conventional TCD probe on 36 participants, showing a mean difference and standard deviation of difference as -1.51 ± 4.34 cm s-1, -0.84 ± 3.06 cm s-1 and -0.50 ± 2.55 cm s-1 for peak systolic velocity, mean flow velocity, and end diastolic velocity, respectively. The measurement success rate was 70.6%, compared with 75.3% for a conventional TCD probe. Furthermore, we demonstrate continuous blood flow spectra during different interventions and identify cascades of intracranial B waves during drowsiness within 4 h of recording.

A wearable cardiac ultrasound imager.

Continuous imaging of cardiac functions is highly desirable for the assessment of long-term cardiovascular health, detection of acute cardiac dysfunction and clinical management of critically ill or surgical patients1-4. However, conventional non-invasive approaches to image the cardiac function cannot provide continuous measurements owing to device bulkiness5-11, and existing wearable cardiac devices can only capture signals on the skin12-16. Here we report a wearable ultrasonic device for continuous, real-time and direct cardiac function assessment. We introduce innovations in device design and material fabrication that improve the mechanical coupling between the device and human skin, allowing the left ventricle to be examined from different views during motion. We also develop a deep learning model that automatically extracts the left ventricular volume from the continuous image recording, yielding waveforms of key cardiac performance indices such as stroke volume, cardiac output and ejection fraction. This technology enables dynamic wearable monitoring of cardiac performance with substantially improved accuracy in various environments.

Perovskite superlattices with efficient carrier dynamics.

Compared with their three-dimensional (3D) counterparts, low-dimensional metal halide perovskites (2D and quasi-2D; B2An-1MnX3n+1, such as B = R-NH3+, A = HC(NH2)2+, Cs+; M = Pb2+, Sn2+; X = Cl-, Br-, I-) with periodic inorganic-organic structures have shown promising stability and hysteresis-free electrical performance1-6. However, their unique multiple-quantum-well structure limits the device efficiencies because of the grain boundaries and randomly oriented quantum wells in polycrystals7. In single crystals, the carrier transport through the thickness direction is hindered by the layered insulating organic spacers8. Furthermore, the strong quantum confinement from the organic spacers limits the generation and transport of free carriers9,10. Also, lead-free metal halide perovskites have been developed but their device performance is limited by their low crystallinity and structural instability11. Here we report a low-dimensional metal halide perovskite BA2MAn-1SnnI3n+1 (BA, butylammonium; MA, methylammonium; n = 1, 3, 5) superlattice by chemical epitaxy. The inorganic slabs are aligned vertical to the substrate and interconnected in a criss-cross 2D network parallel to the substrate, leading to efficient carrier transport in three dimensions. A lattice-mismatched substrate compresses the organic spacers, which weakens the quantum confinement. The performance of a superlattice solar cell has been certified under the quasi-steady state, showing a stable 12.36% photoelectric conversion efficiency. Moreover, an intraband exciton relaxation process may have yielded an unusually high open-circuit voltage (VOC).

Application of 3-Step Laparoscopic Cholecystectomy in Acute Difficult Cholecystitis.

BACKGROUND: With the aging of the global population, the incidence rate of acute cholecystitis is increasing. Laparoscopic cholecystectomy is considered as the first choice to treat acute cholecystitis. How to effectively avoid serious intraoperative complications such as bile duct and blood vessel injury is still a difficult problem that puzzles surgeons. This paper introduces the application of laparoscopic cholecystectomy, a new surgical concept, in acute difficult cholecystitis. METHODS: This retrospective analysis was carried out from January 2019 to January 2021. A total of 36 patients with acute difficult cholecystitis underwent 3-step laparoscopic cholecystectomy. The general information, clinical features, surgical methods, surgical results, and postoperative complications of the patients were analyzed. RESULTS: All patients successfully completed the surgery, one of them was converted to laparotomy, and the other 35 cases were treated with 3-step laparoscopic cholecystectomy. Postoperative bile leakage occurred in 2 cases (5.56%), secondary choledocholithiasis in 1 case (2.78%), and hepatic effusion in 1 case (2.78%). No postoperative bleeding, septal infection, and other complications occurred, and no postoperative colon injury, gastroduodenal injury, liver injury, bile duct injury, vascular injury, and other surgery-related complications occurred. All 36 patients were discharged from hospital after successful recovery. No one died 30 days after surgery, and there was no abnormality in outpatient follow-up for 3 months after surgery. CONCLUSIONS: Three-step laparoscopic cholecystectomy seems to be safer and more feasible for acute difficult cholecystitis patients. Compared with traditional laparoscopic cholecystectomy or partial cholecystectomy, 3-step laparoscopic cholecystectomy has the advantages of safe surgery and less complications, which is worth trying by clinicians.

A fully integrated wearable ultrasound system to monitor deep tissues in moving subjects.

Recent advances in wearable ultrasound technologies have demonstrated the potential for hands-free data acquisition, but technical barriers remain as these probes require wire connections, can lose track of moving targets and create data-interpretation challenges. Here we report a fully integrated autonomous wearable ultrasonic-system-on-patch (USoP). A miniaturized flexible control circuit is designed to interface with an ultrasound transducer array for signal pre-conditioning and wireless data communication. Machine learning is used to track moving tissue targets and assist the data interpretation. We demonstrate that the USoP allows continuous tracking of physiological signals from tissues as deep as 164 mm. On mobile subjects, the USoP can continuously monitor physiological signals, including central blood pressure, heart rate and cardiac output, for as long as 12 h. This result enables continuous autonomous surveillance of deep tissue signals toward the internet-of-medical-things.

Geomechanical log responses and identification of fractures in tight sandstone, West Sichuan Xinchang Gas Field.

Natural fractures provide important reservoir space and migration channels for oil and gas in tight reservoirs. Moreover, they are key factors controlling the high yield of tight oil and gas. Accordingly, methods to identify and characterize fractures are essential; however, conventional well-logging data are not ideal for such purposes. To this end, our study proposed an efficient method for identifying and characterizing fractures. First, core observations, core sample test analysis, numerical simulations, core calibration of borehole image logs, and borehole image log calibration of conventional logs were performed to identify sensitive log curves and log response characteristics of fractures. Second, we analyzed the response characteristics and differences in the log and properties of tight sandstone with and without fractures. Third, logging eigenvalue (EvF) and rock physical eigenvalue (MvF) models were constructed to determine different causes of fractures in tight sandstone. Finally, the two models were applied to identify and characterize fractures in the tight sandstone reservoirs in the West Sichuan Xinchang gas field, China. It was found that the effect of using the logging eigenvalue and rock physical eigenvalue models to identify fractures was similar to that observed using an image log. Overall, different fractures were accurately identified and characterized, indicating that the proposed method efficiently identifies and characterizes fractures in tight sandstone, ultimately advancing the research of fine reservoir evaluation and fracture theory.

Building capacity for health promotion--a case study from China.

During the period 1997-2000 a technical assistance project to build capacity for community-based health promotion was implemented in seven cities and one province in China. The technical assistance project formed part of a much larger World Bank supported program to improve disease prevention capabilities in China, commonly known as Health VII. The technical assistance project was funded by the Australian Agency for International Development. It was designed to develop capacity within the Ministry of Health (MOH) and the cities and province in the management of community-based health promotion projects, as well as supporting institutional development and public health policy reform. There are some relatively unique features of this technical assistance which helped shape its implementation and impact. It sought to provide the Chinese MOH and the cities and province with an introduction to comprehensive health promotion strategies, in contrast to the more limited information, education and communication strategies. The project was provided on a continuing basis over 3 years through a single institution, rather than as a series of ad hoc consultancies by individuals. Teaching and learning processes were developmental, leading progressively to a greater degree of local Chinese input and management to ensure sustainability and maintenance of technical support for the project. Based on this experience, this paper presents a model for capacity building projects of this type. It describes the education, training and planning activities that were the key inputs to the project, as well as the limited available evidence on the impact of the project. It describes how the project evolved over time to meet the changing needs of the participants, specifically how the content of the project shifted from a risk-factor orientation to a settings-based focus, and the delivery of the project moved from an expert-led approach to a more participatory, problem based learning approach. In terms of impact, marked differences before and after the implementation of the training activities were identified in key areas for reform, in addition to the self reported positive change in knowledge, and a high level of participant satisfaction. Key lessons are summarized. Technical assistance projects of this kind benefit from continuity and a high level of coordination, the provision of culturally and linguistically appropriate teaching, and a clear understanding of the need to match workforce development with organizational/institutional development.