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result(s) for
"Cheng, Tian-Le"
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Phase-field model of precipitation processes with coherency loss
2021
A phase-field model is proposed to simulate coherency loss coupled with microstructure evolution. A special field variable is employed to describe the degree of coherency loss of each particle and its evolution is governed by a Ginzburg-Landau type kinetic equation. For the sake of computational efficiency, a flood-fill algorithm is introduced that can drastically reduce the required number of field variables, which allows the model to efficiently simulate a large number of particles sufficient for characterizing their statistical features during Ostwald ripening. The model can incorporate size dependence of coherency loss, metastability of coherent particles, and effectively incorporate the underlying mechanisms of coherency loss by introducing a so-called differential energy criterion. The model is applied to simulate coarsening of Al3Sc precipitates in aluminum alloy and comprehensively compared with experiments. Our results clearly show how the particle size distribution is changed during coherency loss and affects the coarsening rate.
Journal Article
Phase-field framework with constraints and its applications to ductile fracture in polycrystals and fatigue
2022
Modeling of ductile fracture in polycrystalline structures is challenging, since it requires integrated modeling of cracks, crystal plasticity, and grains. Here we extend the typical phase-field framework to the situations with constraints on the order parameters, and formulate two types of phase-field models on ductile fracture. The Type-I model incorporates three sets of order parameters, which describe the distributions of cracks, plastic strain, and grains, respectively. Crystal plasticity is employed within grain interiors accommodated by J2 plasticity at grain boundaries. The applications of the Type-I model to single crystals and bicrystals demonstrate the influences of grain orientations and grain boundaries on crack growth. In the Type-II model, J2 plasticity is assumed for the whole system and grain structures are neglected. Taking advantage of the efficiency of the fast Fourier transform, our Type-II model is employed to study low cycle fatigue. Crack closure and striation-like patterning of plastic strain are observed in the simulations. Crack growth rate is analyzed as a function of the J-integral, and the simulated fatigue life as a function of plastic strain agrees with the Coffin–Manson relation without a priori assumption.
Journal Article
DDX3X induces mesenchymal transition of endothelial cells by disrupting BMPR2 signaling
2025
Endothelial‐to‐mesenchymal transition (EndoMT), a widely recognized biological process leading to abnormal endothelial function, has been implicated in various cardiovascular pathologies. DEAD‐box proteins represent the largest family of RNA helicases associated with multiple physiological and pathophysiological processes; however, their role in the homeostasis of endothelial cells (ECs) remains largely unexplored. Here, we show that the levels of DEAD‐box protein 3 X‐linked (DDX3X), a DEAD‐box RNA helicase protein, were significantly increased during EC transition in vivo and in vitro . DDX3X overexpression promoted EndoMT as well as endothelial dysfunction and inflammation, whereas its downregulation effectively inhibited this transition in ECs. Mechanistically, elevated DDX3X resulted in downregulation of bone morphogenetic protein receptor type 2 (BMPR2), a protein that is pivotal for maintaining endothelial homeostasis and function. Furthermore, our co‐immunoprecipitation assays demonstrated a molecular interplay between DDX3X and BMPR2. Importantly, DDX3X was shown to promote the lysosomal degradation of BMPR2, thereby interrupting its downstream signal transduction. These findings identify DDX3X as a novel regulator of EndoMT by modulating BMPR2 signaling.
Journal Article
SMARCA4-Deficient Undifferentiated Tumor Achieved by Transbronchial Mediastinal Cryobiopsy Additional to Needle Aspiration
by
Herth, Felix J.
,
Zhang, Jing
,
Huang, Zan-Sheng
in
Bronchoscopy
,
Care and treatment
,
DNA Helicases
2023
Lung cancer is the leading cause of deaths from malignant neoplasms worldwide, and a satisfactory biopsy that allows for histological and other analyses is critical for its diagnosis. Guidelines have recommended endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) as the reference standard for the staging of lung cancer. However, the relatively limited sample volume retrieved by needle aspiration might restrict the diagnostic capacity of EBUS-TBNA in other uncommon thoracic tumors. Transbronchial mediastinal cryobiopsy is a recently developed sampling strategy for mediastinal lesions, which demonstrates added diagnostic value to conventional needle aspiration. Here, we present a case of thoracic SMARCA4-deficient undifferentiated tumor successfully diagnosed by mediastinal cryobiopsy additional to EBUS-TBNA.
Journal Article
In Situ Three-Dimensional Reciprocal-Space Mapping of Diffuse Scattering Intensity Distribution and Data Analysis for Precursor Phenomenon in Shape-Memory Alloy
2012
Diffuse scattering contains rich information on various structural disorders, thus providing a useful means to study the nanoscale structural deviations from the average crystal structures determined by Bragg peak analysis. Extraction of maximal information from diffuse scattering requires concerted efforts in high-quality three-dimensional (3D) data measurement, quantitative data analysis and visualization, theoretical interpretation, and computer simulations. Such an endeavor is undertaken to study the correlated dynamic atomic position fluctuations caused by thermal vibrations (phonons) in precursor state of shape-memory alloys. High-quality 3D diffuse scattering intensity data around representative Bragg peaks are collected by using
in situ
high-energy synchrotron x-ray diffraction and two-dimensional digital x-ray detector (image plate). Computational algorithms and codes are developed to construct the 3D reciprocal-space map of diffuse scattering intensity distribution from the measured data, which are further visualized and quantitatively analyzed to reveal
in situ
physical behaviors. Diffuse scattering intensity distribution is explicitly formulated in terms of atomic position fluctuations to interpret the experimental observations and identify the most relevant physical mechanisms, which help set up reduced structural models with minimal parameters to be efficiently determined by computer simulations. Such combined procedures are demonstrated by a study of phonon softening phenomenon in precursor state and premartensitic transformation of Ni-Mn-Ga shape-memory alloy.
Journal Article
Spontaneous Formation of Stable Capillary Bridges for Firming Compact Colloidal Microstructures in Phase Separating Liquids: A Computational Study
2011
Computer modeling and simulations are performed to investigate capillary bridges spontaneously formed between closely packed colloidal particles in phase separating liquids. The simulations reveal a self-stabilization mechanism that operates through diffusive equilibrium of two-phase liquid morphologies. Such mechanism renders desired microstructural stability and uniformity to the capillary bridges that are spontaneously formed during liquid solution phase separation. This self-stabilization behavior is in contrast to conventional coarsening processes during phase separation. The volume fraction limit of the separated liquid phases as well as the adhesion strength and thermodynamic stability of the capillary bridges are discussed. Capillary bridge formations in various compact colloid assemblies are considered. The study sheds light on a promising route to in-situ (in-liquid) firming of fragile colloidal crystals and other compact colloidal microstructures via capillary bridges.
Oxide Scale Exfoliation Analysis of Type T91 SS Boiler Tubes
by
Carney, Casey S.
,
Holcomb, Gordon R.
,
Xue, Fei
in
Boiler tubes
,
Boilers
,
Cracking (fracturing)
2020
Oxide scale exfoliation behavior of Type T91 stainless steel (SS) (UNS K91560) boiler tubes is analyzed by modeling the stresses within the steam-side oxide. Ourmodel includes the contributions from thermal stress, creep, and oxide growth stress, and simulates oxide stress evolutions under subcritical and supercritical steam conditions. Simulation results demonstrate that creep increases the oxide stresses due to differing creep rates between oxide and metal, especially under supercritical steam conditions. Damage maps are constructed by comparing the calculated stresses to the critical stress for through-scale cracking, which show that oxide scales in supercritical boilers exfoliate about one year earlier than those in subcritical boilers.
Magazine Article
Association of Peripheral Blood Cell Profile With Alzheimer's Disease: A Meta-Analysis
2022
Background: Inflammation and immune dysfunction play significant roles in the pathogenesis of Alzheimer's disease (AD)-related dementia. Changes in peripheral blood cell profiles are a common manifestation of inflammation and immune dysfunction and have been reported in patients with AD or mild cognitive impairment (MCI). We systematically evaluated the association of peripheral blood cell counts and indices with AD or MCI through a meta-analysis. Methods: We electronically searched sources to identify all case‒control trials comparing peripheral blood cell counts and/or lymphocyte subsets between patients with AD or MCI and healthy controls (HCs). Meta-analyses were used to estimate the between-group standardized mean difference (SMD) and 95% confidence interval (CI). Results: A total of 36 studies involving 2,339 AD patients, 608 MCI patients, and 8,352 HCs were included. AD patients had significantly decreased lymphocyte counts (SMD -0.345, 95% CI [-0.545, -0.146], P = 0.001) and significantly increased leukocyte counts (0.140 [0.039, 0.241], P = 0.006), neutrophil counts (0.309 [0.185, 0.434], P = 0.01), and neutrophil‒lymphocyte ratio (NLR) (0.644 [0.310, 0.978], P < 0.001) compared to HCs. Similarly, significantly increased leukocyte counts (0.392 [0.206, 0.579], P < 0.001), NLR (0.579 [0.310, 0.847], P < 0.001), and neutrophil counts (0.248 [0.121, 0.376], P < 0.001) were found in MCI patients compared with HCs. A significantly decreased percentage of B lymphocytes (-1.511 [-2.775, -0.248], P = 0.019) and CD8+ T cells (-0.760 [-1.460, -0.061], P = 0.033) and a significantly increased CD4/CD8 ratio (0.615 [0.074, 1.156], P = 0.026) were observed in AD patients compared to HCs. Furthermore, significant changes in hemoglobin level and platelet distribution width were found in patients with AD or MCI compared with HCs. However, no significant difference was found between AD or MCI patients and HCs in latelet counts, mean corpuscular volume, red cell distribution width, mean platelet volume, and CD4+ T, CD3+ T, or natural killer cell counts. Conclusion: Changes in peripheral blood cell profiles, particularly involving leukocyte, lymphocyte, neutrophil, and CD8+ T cell counts, as well as the NLR and the CD4/CD8 ratio, are closely associated with AD. The diagnostic relevance of these profiles should be investigated in future.
Journal Article
Targeting mitochondria: restoring the antitumor efficacy of exhausted T cells
2024
Immune checkpoint blockade therapy has revolutionized cancer treatment, but resistance remains prevalent, often due to dysfunctional tumor-infiltrating lymphocytes. A key contributor to this dysfunction is mitochondrial dysfunction, characterized by defective oxidative phosphorylation, impaired adaptation, and depolarization, which promotes T cell exhaustion and severely compromises antitumor efficacy. This review summarizes recent advances in restoring the function of exhausted T cells through mitochondria-targeted strategies, such as metabolic remodeling, enhanced biogenesis, and regulation of antioxidant and reactive oxygen species, with the aim of reversing the state of T cell exhaustion and improving the response to immunotherapy. A deeper understanding of the role of mitochondria in T cell exhaustion lays the foundation for the development of novel mitochondria-targeted therapies and opens a new chapter in cancer immunotherapy.
Journal Article
Rational application of EGFR-TKI adjuvant therapy in patients with completely resected stage IB-IIIA EGFR-mutant NSCLC: a systematic review and meta-analysis of 11 randomized controlled trials
2023
Purpose
To determine the role and rational application of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) adjuvant therapy in patients with completely resected stage IB-IIIA EGFR-mutant non-small-cell lung cancer (NSCLC).
Method
Randomized controlled trials (RCTs) that compared the survival outcomes between adjuvant EGFR-TKIs and adjuvant chemotherapy or a placebo, or between different EGFR-TKI treatment durations for resected NSCLC, were eligible for inclusion. Disease-free survival (DFS) and overall survival (OS) with hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated as effective measures using random-effect or fixed-effect models. Subgroup analysis was also performed.
Results
Eleven RCTs involving 2102 EGFR-mutant NSCLC patients with or without EGFR-TKI adjuvant therapy were included. For all stage IB-IIIA NSCLC patients, EGFR-TKIs adjuvant therapy could not only significantly improve DFS (HR 0.43, 95% CI 0.30–0.63, P < 0.001) and 2- and 3-year DFS rates, but also improve OS (HR 0.72, 95% CI, 0.54–0.96, P = 0.024), compared with chemotherapy or the placebo. Further subgroup analyses indicated prolonged OS from first-generation EGFR-TKI adjuvant therapy in stage III patients, compared with chemotherapy or the placebo (HR for OS, 0.34; 95% CI, 0.18–0.63; P = 0.001). Of note, osimertinib adjuvant therapy led to the OS benefit expanding from stage III to stage II-III patients, with significantly improved DFS and a lower risk of brain recurrence, compared with the placebo. A 2-year treatment duration with EGFR-TKI adjuvant therapy showed a significantly lower recurrence risk than a ≤ 1-year duration.
Conclusion
The DFS advantage from first-generation EGFR-TKI adjuvant therapy can translate into an OS benefit in stage III NSCLC patients. Osimertinib might be more suitable for adjuvant therapy than first-generation EGFR-TKIs, because of the lower recurrence rate and the potential OS benefit even in early-stage patients. The optimal treatment duration for EGFR-TKIs at different stages of disease needs to be validated.
Journal Article