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Generalized polynomial chaos expansion by reanalysis using static condensation based on substructuring

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 819-836页

作者： d.lee S.CHANG J.lee department of Automotive Engineering Hanyang UniversitySeoul 04763Republic of Korea School of Mechanical Engineering Chungnam National UniversityDaejeon 34134Republic of Korea department of Mechanical Robotics and Energy EngineeringDongguk UniversitySeoul 04620Republic of Korea

This paper presents a new computational method for forward uncertainty quantification(UQ)analyses on large-scale structural systems in the presence of arbitrary and dependent random inputs.The method consists of a generalized polynomial chaos expansion(GPCE)for statistical moment and reliability analyses associated with the stochastic output and a static reanalysis method to generate the input-output data set.In the reanalysis,we employ substructuring for a structure to isolate its local regions that vary due to random inputs.This allows for avoiding repeated computations of invariant substructures while generating the input-output data set.Combining substructuring with static condensation further improves the computational efficiency of the reanalysis without losing accuracy.Consequently,the GPCE with the static reanalysis method can achieve significant computational saving,thus mitigating the curse of dimensionality to some degree for UQ under high-dimensional inputs.The numerical results obtained from a simple structure indicate that the proposed method for UQ produces accurate solutions more efficiently than the GPCE using full finite element analyses(FEAs).We also demonstrate the efficiency and scalability of the proposed method by executing UQ for a large-scale wing-box structure under ten-dimensional(all-dependent)random inputs.

关键词： forward uncertainty quantification(UQ) generalized polynomial chaos expansion(GPCE) static reanalysis method static condensation substructuring

Flexural-wave-generation using a phononic crystal with a piezoelectric defect

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Applied Mathematics and Mechanics(English Edition) 2023年第8期44卷 1241-1262页

作者： S.H.JO d.lee department of Mechanical Roboticsand Energy EngineeringDongguk UniversitySeoul 04620Republic of Korea department of Mechanical Engineering Seoul National UniversitySeoul 08826Republic of Korea

This paper proposes a method to amplify the performance of a flexural-wave-generation system by utilizing the energy-localization characteristics of a phononic crystal(PnC)with a piezoelectric defect and an analytical approach that accelerates the predictions of such wave-generation performance.The proposed analytical model is based on the Euler-Bernoulli beam theory.The proposed analytical approach,inspired by the transfer matrix and S-parameter methods,is used to perform band-structure and time-harmonic analyses.A comparison of the results of the proposed approach with those of the finite element method validates the high predictive capability and time efficiency of the proposed model.A case study is explored;the results demonstrate an almost ten-fold amplification of the velocity amplitudes of flexural waves leaving at a defect-band frequency,compared with a system without the PnC.Moreover,design guidelines for piezoelectric-defect-introduced PnCs are provided by analyzing the changes in wave-generation performance that arise depending on the defect location.

关键词： phononic crystal(PnC) defect wave-generation fexural wave analytical model

Glucose metabolism in amyotrophic lateral sclerosis:it is bitter-sweet

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Neural Regeneration Research 2022年第9期17卷 1975-1977页

作者： Titaya Lerskiatiphanich Jianina Marallag John d.lee School of Biomedical Sciences Faculty of MedicineThe University of QueenslandSt LuciaBrisbaneQLDAustralia

A recent study by Mcdonald et al.(2021)focused on how peripheral glucose metabolism and handling are compromised in amyotrophic lateral sclerosis(ALS).dysfunctions in glucose and energy metabolism have been identified in transgenic mouse models and patients with ALS.However,how these processes are altered and contribute to disease progression are not fully understood.The aforementioned study has identified several changes to glucose homeostasis in the transgenic SOd1G93A mouse model of ALS at the later stages of the disease.Specifically,the authors found that despite insulin resistance being present,there was increased glucose uptake in ALS mice,and increased glycogen accumulation in the liver.Additionally,there was evidence of glucagon resistance developing in these mice,which supports clinical observations.This perspective outlines the key aspects of glucose metabolism and demonstrates how multiple pathways relating to these processes are compromised in ALS.

关键词： metabolism amyotrophic homeostasis

Complement:a global immunometabolic regulator in amyotrophic lateral sclerosis

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Neural Regeneration Research 2021年第6期16卷 1210-1211页

作者： Martin W.Lo John d.lee School of Biomedical Sciences Faculty of MedicineThe University of QueenslandSt LuciaQueenslandAustralia

Recently,Mcdonald et al.(2020)proposed that complement causes a metabolic switch to lipid consumption in amyotrophic lateral sclerosis(ALS),which raises the possibility of complement as a global immunometabolic regulator.In ALS,neuromuscular degeneration occurs concurrently with complement-mediated inflammation,glucose intolerance,and elevated lipid consumption.Moreover,complement is being increasingly recognized as a metabolic regulator that can induce insulin resistance and alter fuel source selection.Thus,the authors propose that chronic complement activation may be driving metabolic reprogramming in ALS,which has broad implications for the field of immunometabolism and would be the first mechanistic explanation of the“lipid switch”in ALS.Specifically,it suggests that complement can drive a global shift in resources during inflammation,in which glucose is redirected from peripheral tissues to immune cells to support their inflammatory actions.

关键词： inflammation metabolism elevated

Nano-revolution in hepatocellular carcinoma: A multidisciplinary odyssey - Are we there yet?

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WORLd JOURNAL OF HEPATOLOGY 2024年第5期16卷 684-687页

作者： lee, Howard d. Yuan, Li-Yun Univ Southern Calif Keck Sch Med Dept Med Div Gastrointestinal & Liver Dis 1975 Zonal Ave Los Angeles CA 90033 USA

In this editorial we comment on the review by Zhou et al reviewing the landscape of nanomedicine in the treatment of hepatocellular carcinoma (HCC). We focus on the immense potential of nanotechnology, particularly ligand-receptor mediated nanotherapy, in revolutionizing the treatment landscape of HCC. despite advancements in multidisciplinary treatment, HCC remains a significant global health challenge. Ligand-mediated nanotherapy offers the opportunity for precise drug delivery to tumor sites, targeting specific receptors overexpressed in HCC cells, thereby enhancing efficacy and minimizing side effects. Overcoming drug resistance and aggressive tumor biology is facilitated by nanomedicine, bypassing traditional hurdles encountered in chemotherapy. Examples include targeting glypican-3, asialoglycoprotein, transferrin receptor or folic acid receptors, capitalizing on their over-expression in tumor cells. The ability for multi-receptor targeting through dual-ligand nanoparticle modification holds the prospect of further enhancement in specificity and efficacy of directed therapy. However, challenges including immune responses, reproducibility in nanoparticle synthesis, and production scalability remain. Future directions involve refining targeting strategies, improving drug release mechanisms, and streamlining production processes to enable personalized and multifunctional nanotherapies. Overall, the integration of nanotherapy in HCC treatment holds immense promise, but continued partnership and effort are needed in offering hope for more effective, precise, and accessible clinical care in the management of HCC.

关键词： Hepatocellular carcinoma Nanomedicine Ligand-receptor mediated nanotherapy Precision medicine Personalized medicine Targeting dELIVERY

Nanoscale resistive switching devices for memory and computing applications

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Nano Research 2020年第5期13卷 1228-1243页

作者： Seung Hwan lee Xiaojian Zhu Wei d.Lu department of Electrical Engineering and Computer Science The University of MichiganAnn ArborMichigan 48109USA

With the slowing down of the Moore’s law and fundamental limitations due to the von-Neumann bottleneck,continued improvements in computing hardware performance become increasingly more challenging.Resistive switching(RS)devices are being extensively studied as promising candidates for next generation memory and computing applications due to their fast switching speed,excellent endurance and retention,and scaling and three-dimensional(3d)stacking capability.In particular,RS devices offer the potential to natively emulate the functions and structures of synapses and neurons,allowing them to efficiently implement neural networks(NNs)and other in-memory computing systems for data intensive applications such as machine learning tasks.In this review,we will examine the mechanisms of RS effects and discuss recent progresses in the application of RS devices for memory,deep learning accelerator,and more faithful brain-inspired computing tasks.Challenges and possible solutions at the device,algorithm,and system levels will also be discussed.

关键词： resistive switching oxygen vacancy metal cation memory application in-memory computing bio-inspired application

Glutamic acid supplementation recovers the reduced performance of weanling pigs fed reduced crude protein diets

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Animal Nutrition 2022年第1期8卷 249-255页

作者： Santi d.Upadhaya Sang Seon lee Young Hwa Kim Zhenlong Wu In Ho Kim department of Animal Resource and Science Dankook UniversityNo.29 AnseodongCheonanChoongnam 31116South Korea National Institute of Animal Science 114 Sinbangro-1 GilSeongjwan-eupSeobuk-guCheonan-si31000South Korea State Key Laboratory of Animal Nutrition Department of Animal Nutrition and Feed ScienceChina Agricultural UniversityBeijing 100193China

This study was conducted to evaluate the supplementation of glutamic acid(Glu)to reduced protein diets on the performance of weanling pigs.One hundred and eighty crossbred weanling pigs([YorkshireLandrace]duroc,21 d old)having similar body weight(BW)of 6.45 kg were randomly allotted to 1 of 6 dietary treatments(5 pigs per pen[2 barrows and 3 gilts];6 pens per treatment)based on BW and sex during a 6-week trial.dietary treatments consisted of positive control(PC)diet formulated to have 226.9,205.6,and 188.8 g crude protein(CP)during phases 1,2,and 3,respectively,and negative control(NC)diets with 20 g CP reduction from PC diets and addition of Glu with increasing levels,resulting in the calculated Lys-to-Glu ratios of 1:2.25,1:2.30.1:2.35,1:2.40,and 1:2.45,designated as NC,NC1,NC2,NC3,and NC4,respectively.The BW of pigs receiving PC diet was higher(Pdiet at d 7,21 and 42.A higher(Pdaily gain(AdG)from d 1 to 7,8 to 21,22 to 42 and during the overall experiment period was observed in pigs fed PC than NC diet.Pigs fed NC diets including the graded level of Glu linearly increased(Pd 42,AdG and gain-to-feed ratio(G:F)during the overall experimental period.In addition,trends in linear increase in BW(P=0.056)at d 7 and AdG from d 1 to 7 and d 22 to 42(linear effect,P=0.081,P=0.058 respectively)were observed.A tendency in the linear increment of NH3(P=0.082)at d 21 and linear reduction in methyl mercaptans(P=0.054)emission at d 42 was observed in pigs fed NC diets supplemented with graded level of Glu.In conclusion,supplementing the reduced protein diet with Glu enhanced the growth performance in weanling pigs suggesting that supplementation of Glu can compensate the reduction of 2%CP in the basal diets.

关键词： Glu Growth performance Reduced protein diet Weanling pig

Long-term, in vivo therapeutic effects of a single dose of miR-145 micelles for atherosclerosis

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Bioactive Materials 2023年第9期27卷 327-336页

作者： deborah d.Chin Neil Patel Woori lee Sonali Kanaya Jackson Cook Eun Ji Chung department of Biomedical Engineering University of Southern CaliforniaLos AngelesCA90089United States division of Vascular Surgery and Endovascular Therapy Department of SurgeryKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCA90033United States Mork Family department of Chemical Engineering and Materials Science University of Southern CaliforniaLos AngelesCA90089United States Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCA90033United States division of Nephrology and Hypertension Department of MedicineKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCA90033United States Norris Comprehensive Cancer Center Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCA90089United States

Atherosclerosis is a chronic inflammatory disease that is characterized by the build-up of lipid-rich plaques in the arterial walls. The standard treatment for patients with atherosclerosis is statin therapy aimed to lower serum lipid levels. despite its widespread use, many patients taking statins continue to experience acute events. Thus, to develop improved and alternative therapies, we previously reported on microRNA-145 (miR-145 micelles) and its ability to inhibit atherosclerosis by targeting vascular smooth muscle cells (VSMCs). Importantly, one dose of miR-145 micelles significantly abrogated disease progression when evaluated two weeks post-administration. Thus, in this study, to evaluate how long the sustained effects of miR-145 micelles can be maintained and towards identifying a dosing regimen that is practical for patients with chronic disease, the therapeutic effects of a single dose of miR-145 micelles were evaluated for up to two months in vivo. After one and two months post-treatment, miR-145 micelles were found to reduce plaque size and overall lesion area compared to all other controls including statins without causing adverse effects. Furthermore, a single dose of miR-145 micelle treatment inhibited VSMC transdifferentiation into pathogenic macrophage-like and osteogenic cells in plaques. Together, our data shows the long-term efficacy and sustained effects of miR-145 micelles that is amenable using a dosing frequency relevant to chronic disease patients.

关键词： MicroRNA-145 Atherosclerosis Vascular smooth muscle cell Nanoparticle Gene therapy

Model-based adaptive locomotion and clustering control of microparticles through ultrasonic topological charge modulation

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Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 623-640页

作者： H.S.lee H.X.CAO d.JUNG C.S.KIM School of Mechanical Engineering Chonnam National UniversityGwangju 61186South Korea Korea Institute of Medical Microrobotics Gwangju 61011South Korea

We present a novel motion control technique for microrobot clusters to exploit the characteristics of the ultrasonic field.The method comprises two steps,i.e.,introducing an ultrasonic actuation(UA)linear model for three-dimensional(3d)locomotion and controlling the topological charge(TC)in the ultrasonic vortex for microrobot clustering.Here,the TC is a controllable parameter for the expansion and contraction of the pressure null space inside the vortex.We present a TC control method to cluster sporadically distributed microrobots in a specific workspace.To validate the concept,a UA system composed of 30 ultrasonic transducers with 1 MHz frequency is fabricated,and the characteristics of the generated acoustic pressure field are analyzed through simulations.Subsequently,the performances of the adaptive controller for precise 3d locomotion and the TC control method for clustering are evaluated.Finally,the UA technology,which performs both clustering and locomotion in a complex manner,is validated with a gelatin phantom in an in-vitro environment.

关键词： ultrasonic actuation(UA) topological charge(TC) adaptive control particle manipulation