497 research outputs found
A Delayed Detached Eddy Simulation Model with Low Reynolds Number Correction for Transitional Swirling Flow in a Multi-Inlet Vortex Nanoprecipitation Reactor
No full textThe objective of the presented work is to verify a delayed detached eddy simulation (DDES) model for simulating transitional swirling flow in a micro-scale multi-inlet vortex reactor (MIVR). The DDES model is a k-w based turbulence model with a low Reynolds number correction applied to the standard k-w model such that the Reynolds-averaged Navier-Stokes (RANS) component of the DDES model is able to account for low Reynolds number flow. By limiting the dissipation rate in the k-equation, the large-eddy simulation (LES) part of the DDES model behaves similarly to a one-equation sub-grid model. The turbulent Reynolds number is redefined to represent both modeled and resolved turbulence level so that underestimation of the RANS length scale in the LES range can be reduced. Applying the DDES model to simulate both laminar and transitional flow in the micro-scale MIVR produces an accurate prediction of mean velocity and turbulent intensity compared with experimental data. It is demonstrated that the proposed DDES model is capable of simulating transitional flow in the complex geometry of the micro-scale MIVR. These simulation results also help to understand the flow and mixing patterns in the micro-scale MIVR and provide guidances to optimize the reactor for the application of producing functional nanoparticles.This is a manuscript of an article published as Liu, Zhenping, James C. Hill, Rodney O. Fox, Alberto Passalacqua, and Michael G. Olsen. "A Delayed Detached Eddy Simulation Model with Low Reynolds Number Correction for Transitional Swirling Flow in a Multi-Inlet Vortex Nanoprecipitation Reactor." Chemical Engineering Science (2018). DOI: 10.1016/j.ces.2018.08.020. Posted with permission.</p
An investigation into catalysts to improve the low temperature performance of an SCR
No full textSelective catalytic reduction with NH3 is considered as one of the most effective technologies controlling NOx emission. Metal Fe based catalysts were used in the investigation to improve the low temperature performance of NOx conversion. The temperature range studied was between 150 degrees C and 350 degrees C with the interval of 50 degrees C. The honeycomb catalysts were prepared by an impregnation method. The study also included characterization of catalysts by BET, XRD, H2-TPR, SEM and XPS methods. It is found an increase in metal Fe content from 2 to 6 % wt. offers an improvement in the catalytic performance. However, a further increment in Fe content will result in a decrease in its performance. More than 90 % NOx conversion rate could be achieved over the Fe-based honeycomb catalyst at a low temperature by doping with Ni and Zr metal with different weights. Among all the catalysts studied, the mixed metal catalyst of Fe-Ni-Zr is found the most potential one, not only because of its higher NOx conversion rate at a low temperature, but also because of its wider operation temperature window. The effect of gas hourly space velocity (GHSV) was also investigated in the study and results show as GHSV increases that reduction of NOx is decreased
Genetic Regulatory Perturbation of Gene Expression Impacted by Genomic Introgression in Fiber Development of Allotetraploid Cotton
No full textInterspecific genomic introgression is an important evolutionary process with respect to the generation of novel phenotypic diversity and adaptation. A key question is how gene flow perturbs gene expression networks and regulatory interactions. Here, an introgression population of two species of allopolyploid cotton (Gossypium) to delineate the regulatory perturbations of gene expression regarding fiber development accompanying fiber quality change is utilized. De novo assembly of the recipient parent (G. hirsutum Emian22) genome allowed the identification of genomic variation and introgression segments (ISs) in 323 introgression lines (ILs) from the donor parent (G. barbadense 3–79). It documented gene expression dynamics by sequencing 1,284 transcriptomes of developing fibers and characterized genetic regulatory perturbations mediated by genomic introgression using a multi-locus model. Introgression of individual homoeologous genes exhibiting extreme low or high expression bias can lead to a parallel expression bias in their non-introgressed duplicates, implying a shared yet divergent regulatory fate of duplicated genes following allopolyploidy. Additionally, the IL N182 with improved fiber quality is characterized, and the candidate gene GhFLAP1 related to fiber length is validated. This study outlines a framework for understanding introgression-mediated regulatory perturbations in polyploids, and provides insights for targeted breeding of superior upland cotton fiber.This article is published as Chen, Xinyuan, Xiubao Hu, Guo Li, Corrinne E. Grover, Jiaqi You, Ruipeng Wang, Zhenping Liu et al. "Genetic Regulatory Perturbation of Gene Expression Impacted by Genomic Introgression in Fiber Development of Allotetraploid Cotton." Advanced Science (2024): 2401549. doi:10.1002/advs.202401549. © 2024 The Author(s). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
A fundamental investigation of scaling up turbulent liquid-phase vortex reactor using experimentally validated CFD models
No full textThe production of uniform-sized nanoparticles has potential application in a wide variety of fields, but is still a challenge. One main reason that many lab-scale manufactured nanoparticles have not appeared in industry is because there is lack of control on physical properties and surface functionality of nanoparticles during massive production. Recently, a process called "Flash Nanoprecipitation (FNP)" has been developed to produce nanoparticles with controlled size and high drug-loading rate. In FNP, fast mixing is required to make sure that solvent and non-solvent mix homogeneously so that competitive precipitation of organics and polymer could result in functional nanoparticles with narrow size distribution. A multi-inlet vortex reactor (MIVR) has been developed to provide fast mixing for the FNP. The MIVR includes four inlets which are tangential to the mixing chamber of reactor. The MIVR has the operational advantage of providing different inlet-flow momentum and configurations compared to other reactors used in the FNP such as confined impinging jet reactor (CIJR). Former studies have already shown its ability of providing fast mixing and successfully producing functional nanoparticles in the FNP. However, until now all previous investigations about the MIVR only focused in its micro-scale (dimensions in millimetre).
While the micro-scale MIVR does show great promise in the production of functional nanoparticles, the small dimensions and correspondingly small output of the micro-scale MIVR limit its usefulness to producing functional nanopraticles for applications requiring small production run such as high-value pharmaceutical agents. Some applications such as nanoparticle used in pesticides and cosmetics may require larger production run than the micro-scale MIVR can provide, making it economically unrealistic based on the relatively high capital and operating costs needed for a large number of reactors operating in parallel. For this reason, in the study we are interested in investigating the feasibility of scaling up the FNP process to a macro-scale MIVR capable of generating large quantities of functional nanoparticles, both rapidly and economically, and consequently developing experimentally verified computational fluid dynamics (CFD) models that can be used as design tools for further optimizing reactor design and operation parameters to produce customized functional nanoparticles. To accomplish this investigation, a macro-scale MIVR has been built with optical access. Non-intrusive, optical-based measurement techniques including particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) were used to measure flow field and mixing, and related CFD models, specifically turbulence models were validated and developed for optimizing the MIVR and future model development of the FNP process.</p
NaCl interaction during hydration as studied by NMR
No full textWith freshwater getting scares seawater, i.e., water containing NaCl, can become the only viable option for making concrete. Although a lot of research had been directed to understanding the role of water in cement hydration, not much is known about the interaction of the Na+ and Cl- with cement paste during drying. A problem is that available techniques like, i.e., XRD, SEM, and EDX, for measuring the microstructure and the methods for determining the concentration of Na+, Cl- ions in pore solutions are either indirect or invasive and moreover often destructive, which consequently may lead to inadequate interpretations. Using a specially designed Nuclear Magnetic Resonance (NMR) setup, the 1H, 23Na and 35Cl content in cementitious materials can be measured quasi-simultaneously and hence give us direct information on the interaction of the ions and the microstructure development. We have studied the influence factor, i.e., the water-cement ratio, on the microstructure development and the binding of Cl- and Na+. It was found that during the initial hydration stage more Cl- is bound in comparison to Na+ . This is reversed during the acceleration period after which there is a preference for binding of Na+ in comparison to Cl-. Increase of W/C ratio results in less binding capability of Na+ and Cl-
Numerical simulation on the effect of jet nozzle position on impingement cooling of gas turbine blade leading edge
No full textMulti-objective optimization of continuous casting secondary cooling water based on differential evolution algorithm
No full textAbstract A30: Modeling an immunotherapy of NK mechanism on a NSCLC patient derived xenograft
No full textAbstract
The recent clinical successes of immune checkpoint inhibitors have fueled the intense interest in novel immuno-oncology (I/O) therapeutics. The lack of relevant animal models remains a major hurdle in understanding the mechanism of action and evaluating the efficacy of such therapeutics. Patient derived xenograft (PDX), considered to most closely mimic patient tumors in both histo- and molecular pathology1,2, is however rarely used in I/O studies because it grow only in immune-compromised hosts. In reality, many PDXs grow well in nude mice where certain immune functions remain intact, excluding T-cells/T-cell functions. Therefore, PDX could still potentially be of practical use for studying T-cell independent I/O therapy. This study set out to evaluate a biologics for the treatment of a patient derived xenograft disease, by activating mouse natural killer (NK). NK and CD8 T cells are two major immune effector cell types that mediate cytotoxicity to tumor cells in vivo. One of the immunomodulatory agents, an anti-PD-L1 antibody-based IL-15 immunocytokine, was recently tested as a novel I/O treatment of cancer3. This molecule was engineered to be cross-species for both human and mouse PD-L1 and IL-15 that antagonize PD1/PD-L1 checkpoint-mediated immune suppression and also target the PD-L1-expressing tumor with IL-15 stimulated NK and CD8 T effector cells into local tumor sites, thus synergizing tumor-located anti-tumor immunity. In fact, our previous studies have demonstrated a greatly enhanced anti-tumor activity in the PDL-1-expressing syngeneic mouse tumor models via the mobilization of tumor infiltrating lymphocyte (TILs), over the PD-L1 antibody alone3. Since IL-15 also stimulates NKs in addition to T-cells, we reasoned that this bifunctional agent could also have potential activity against a PD-L1-expressing PDX in nude mice where NK remains functional. LU1901 is previously described NSCLC-PDX1, and was confirmed to express high level of PD-L1 by both RNAseq and flow analysis, after screening of a large panel of PDXs. We implanted LU1901 in Balb/c nude mice, and started to treat the mice by the bifunctional agent when the tumor reached to 150 mm3. Our result clearly demonstrated a significant inhibition of LU1901 growth by the bifunctional agent in nude mice, in the apparent absence of T-cells. When the treated tumors were examined at the termination, significantly infiltrate NK cells were found inside the treated tumors, as measured by both flow cytometry and immunohistochemistry (IHC). The number of infiltrating NK also statistically correlates to the amplitude of the tumor responses. Together, our data suggest that one of important mechanisms of action of this bifunctional agent relies on the tumor-targeting NK activation, and also that PDX could be a useful model suitable for in vivo efficacy analysis of T-cell independent immunotherapy.
References
1. Yang, M., et al. Overcoming erlotinib resistance with tailored treatment regimen in patient-derived xenografts from naive Asian NSCLC patients. International journal of cancer. Journal international du cancer 132, E74-84 (2013).
2. Guo, S., Wubin Qian, Jie Cai, Likun Zhang, Jean-Pierre Wery, Qi-Xiang Li. Molecular pathology of patient tumors, patient derived xenografts and cancer cell lines EORTC-NCI-AACR. (2015).
3. Yan Wu, Zhaojing Zhong, Stella Martomo, Dan Lu, Zhanna Polonskaya, Xenia Luna, Haifan Zhang, Zhikai Zhang, Zhun Wang*, Leo Liu*, Jeegar Patel, James Tonra, Henry Li*, Larry Witte, Sam Waksal, Zhenping Zhu. Anti-PD-L1 antibody-based IL-15 immunocytokine has enhanced antitumor immunity. EORTC-NCI-AACR Abstract (2015).
Citation Format: Henry Q. Li, Zhun Wang, Xiaoyu An, Jinping Liu, Likun Zhang, Jean-Pierre Wery, Yan Wu, James Tonra, Sam Waksal, Zhenping Zhu. Modeling an immunotherapy of NK mechanism on a NSCLC patient derived xenograft. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A30.</jats:p
Kaon productions off nucleons and the structure of baryon resonances
No full textThe recent investigations in the chiral quark model show that kaon productions of nucleons play an important role in understanding the structure of baryons. The evidences of a third S-11 resonance in the second resonance region and two narrow states around 2 GeV suggest a set of the molecular type baryons with the hidden strangeness. Confirming these states requires further theoretical and experimental studies of the strangeness production.Astronomy & AstrophysicsPhysics, NuclearPhysics, Particles & FieldsCPCI-S(ISTP)
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