Publications by authors named "Qingchun Lei"

This Letter reports the first demonstration of a high-speed three-dimensional (3D) schlieren technique based on the combination of fiber imaging, Toepler's lens-type schlieren, and computed tomography (CT). The technique uses a single high-speed camera, two xenon lamps, and a series of fiber bundles to simultaneously capture the schlieren images of turbulent flames from seven orientations with a framerate beyond tens of kHz. The presented method complements the existing technique with advantages of being flexible, high speed, and low cost.

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Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor and is characterized by high mortality and morbidity rates and unpredictable clinical behavior. The disappointing prognosis for patients with GBM even after surgery and postoperative radiation and chemotherapy has fueled the search for specific targets to provide new insights into the development of modern therapies. MicroRNAs (miRNAs/miRs) act as oncomirs and tumor suppressors to posttranscriptionally regulate the expression of various genes and silence many target genes involved in cell proliferation, the cell cycle, apoptosis, invasion, stem cell behavior, angiogenesis, the microenvironment and chemo- and radiotherapy resistance, which makes them attractive candidates as prognostic biomarkers and therapeutic targets or agents to advance GBM therapeutics.

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Parkinson's disease (PD) is the second most common neurodegenerative disease amongst the middle‑aged and elderly populations. Several studies have confirmed that the microbiota‑gut‑brain axis (MGBA) serves a key role in the pathogenesis of PD. Changes to the gastrointestinal microbiome (GM) cause misfolding and abnormal aggregation of α‑synuclein (α‑syn) in the intestine.

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As a malignant tumour of the central nervous system, glioma exhibits high incidence and poor prognosis. Although TNIP1 and the TNF-α/NF-κB axis play key roles in immune diseases and inflammatory responses, their relationship and role in glioma remain unknown. Here, we revealed high levels of TNIP1 and TNF-α/NF-κB in glioma tissue.

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Tomographic measurements involve two steps: view registration (VR) to determine the orientation of the projections and the subsequent tomography reconstruction. Therefore, the practical error in both steps impacts the overall accuracy of the final tomographic measurements. Past work treated these two steps separately.

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The prognosis of patients with colorectal cancer (CRC) remains poor owing to diagnosis typically occurring at advanced stages of the disease. The understanding of the molecular regulatory signatures of CRC may lead to the identification of biomarkers for the early detection, prevention and clinical intervention of CRC. Epidemiological studies have indicated that cyclooxygenase‑1 (COX‑1) serves an active function in colon carcinogenesis.

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This Letter reports the first direct comparison between two-dimensional (2D) and three-dimensional (3D) laser-induced fluorescence (LIF) applied to highly turbulent flames, with the goal of experimentally illustrating the capabilities and limitations of volumetric LIF (VLIF). To accomplish these goals, planar LIF (PLIF) and VLIF measurements were simultaneously performed on turbulent flames based on the CH radical. The PLIF measurements imaged a planar cross-section of the target flames across a 2D field-of-view (FOV) of 42  mm×42  mm.

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This work reports the development and experimental validation of a reconstruction algorithm for three-dimensional (3D) nonlinear tomography problems. Many optical tomography problems encountered in practice are nonlinear, for example, due to significant absorption, multiple-scattering, or radiation trapping. Past research efforts have predominately focused on reconstruction algorithms for linear problems, and these algorithms are not readily extendable to nonlinear problems due to several challenges.

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This work reports the experimental demonstration of single-shot visualization of turbulent flows in all three spatial dimensions (3D) based on volumetric laser induced fluorescence (VLIF). The measurements were performed based on the LIF signal of iodine (I2) vapor seeded in the flow. In contrast to established planar LIF (PLIF) technique, the VLIF technique excited the seeded I2 vapor volumetrically by a thick laser slab.

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This work reports the demonstration and analysis of four-dimensional (4D) imaging measurements in two-phase flows using fiber-based endoscopes (FBEs). Such 4D measurements resolve the droplet distribution in two-phase flows in all three spatial directions and with a temporal resolution of up to 5 kHz. Demonstration measurements were performed in a measurement volume of 85 mm × 85 mm × 85 mm discretized into 64 × 64 × 64 voxels to illustrate FBEs' potential for facilitating practical implementation of 4D tomographic measurements.

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Article Synopsis
  • * Controlled experiments tested the FBEs’ performance using a consistent light source, leading to successful 3D flame measurements through a method that combines FBEs with tomography.
  • * The findings show that FBEs can effectively provide detailed quantitative data on flow and combustion, while also being cost-effective and capable of accessing hard-to-reach areas. *
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Turbulent flows inherently feature 3D spatial structures and temporal dynamics. As a result, 4D experimental techniques have been long desired to fully resolve turbulent flows in all three spatial directions and time. This work describes the demonstration of such 4D measurements in two-phase flows using computed tomography and Mie scattering.

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