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A method for large-scale implantation of 3D microdevice ensembles into brain and soft tissue

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Microsystems & Nanoengineering 2020年第1期6卷 199-211页

作者： Stefan A.Sigurdsson Zeyang yu Joonhee lee Arto Nurmikko School of Engineering Brown UniversityProvidenceRI 02912USA Department of Neurology Massachusetts General HospitalBostonMA 02114USA Department of Physics and Astronomy West Virginia UniversityMorgantownWV 26506USA Department of Neuroscience West Virginia UniversityMorgantownWV 26506USA

Wireless networks of implantable electronic sensors and actuators at the microscale(sub-mm)level are being explored for monitoring and modulation of physiological activity for medical diagnostics and therapeutic *** the requirement of integrating multiple electronic or chemical functions within small device volumes,a key challenge is the development of high-throughput methods for the implantation of large numbers of microdevices into soft tissues with minimal *** that end,we have developed a method for high-throughput implantation of~100–200µm size devices,which are here simulated by proxy microparticle *** generally applicable to subdermal tissue,our main focus and experimental testbed is the implantation of microparticles into the *** method deploys a scalable delivery tool composed of a 2-dimensional array of polyethylene glycol-tipped microneedles that confine the microparticle *** dissolution of the bioresorbable polyethylene glycol,the supporting array structure is retrieved,and the microparticles remain embedded in the tissue,distributed spatially and geometrically according to the design of the microfabricated delivery *** first evaluated the method in an agarose testbed in terms of spatial precision and throughput for up to 1000 passive spherical and planar microparticles acting as proxy *** then performed the same evaluations by implanting particles into the rat cortex under acute conditions and assessed the tissue injury produced by our method of implantation under chronic conditions.

关键词： implantation method integrating

Electrically tunable third-harmonic generation using intersubband polaritonic metasurfaces

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Light(Science & Applications) 2024年第8期13卷 1666-1674页

作者： Seongjin Park Jaeyeon yu Gerhard Boehm Mikhail A.Belkin Jongwon lee Department of Electrical Engineering Ulsan National Institute of Science and Technology(UNIST)UlsanRepublic of Korea Walter Schottky Institute Technical University of MunichGarchingGermany

Nonlinear intersubband polaritonic metasurfaces,which integrate giant nonlinear responses derived from intersubband transitions of multiple quantum wells(MQWs)with plasmonic nanoresonators,not only facilitate efficient frequency conversion at pump intensities on the order of few tens of kW cm^(-2)but also enable electrical modulation of nonlinear responses at the individual meta-atom level and dynamic beam *** electrical modulation characteristics of the magnitude and phase of the nonlinear optical response are realized through Stark tuning of the resonant intersubband *** this study,we report,for the first time,experimental implementations of electrical modulation characteristics of mid-infrared third-harmonic generation(THG)using an intersubband polaritonic metasurface based on MQW with electrically tunable third-order nonlinear ***,we achieved a 450%modulation depth of the THG signal,86%suppression of zero-order THG diffraction tuning based on local phase tuning exceeding 180 degrees,and THG beam steering using phase *** work proposes a new route for electrically tunable flat nonlinear optical elements with versatile functionalities.

关键词： tunable tuning pump

Nitrile Electrolyte Strategy for 4.9 V-Class Lithium-Metal Batteries Operating in Flame

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Energy & Environmental Materials 2023年第3期6卷 229-237页

作者： Hyunseok Moon Sung-Ju Cho Dae-Eun yu Sang-Young lee Department of Chemical and Biomolecular Engineering Yonsei UniversitySeoul 03722Korea Molecular Foundry Lawrence Berkeley National LaboratoryBerkeley CA USA Batteries R&D Center LG Energy SolutionDaejeon 34122Korea

Challenges facing high-voltage/high-capacity cathodes,in addition to the longstanding problems pertinent to lithium(Li)-metal anodes,should be addressed to develop high-energy-density Li-metal *** issue mostly stems from interfacial instability between electrodes and *** carbonate-or ether-based liquid electrolytes suffer from not only volatility and flammability but also limited electrochemical stability ***,we report a nitrile electrolyte strategy based on concentrated nitrile electrolytes(CNEs)with *** CNE consists of high-concentration lithium bis(fluorosulfonyl)imide(LiFSI)in a solvent mixture of succinonitrile(SN)/acetonitrile(AN).The SN/AN solvent mixture is designed to ensure high oxidation stability along with thermal stability,which are prerequisites for high-voltage Li-metal *** CNE exhibits interfacial stability with Li metals due to the coordinated solvation *** nitrate(LiNO_(3))and indium fluoride(InF_(3))are incorporated in the CNE as synergistic co-additives to further stabilize solid-electrolyte interphase(SEI)on Li *** resulting electrolyte(CNE+LiNO_(3)/InF_(3))enables stable cycling performance in Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)and 4.9 V-class Li||LiNi_(0.5)Mn_(1.5)O_(4)***,the Li||LiNi_(0.5)Mn_(1.5)O_(4)cell maintains its electrochemical activity at high temperature(100℃)and even in flame without fire or explosion.

关键词： 4.9 V-class cathodes electrolyte-electrode interfaces lithium-metal batteries nitrile electrolytes safety

Effects of the critical breakdown path on the ignition performance in heaterless hollow cathodes

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Plasma Science and Technology 2020年第6期22卷 164-179页

作者： Bo yu Yanda lee Xiaolu KANG Qing ZHAO Center for Information Geoscience School of Resources and EnvironmentUniversity of Electronic Science and Technology of ChinaChengdu 611731People's Republic of China Shanghai Institute of Space Propulsion Shanghai 201112People's Republic of China

The critical breakdown path(CBP)has a significant impact on the breakdown voltage curve and the ignition time of heaterless hollow cathodes(HHCs).To determine the pattern of the variation in the CBP position and its impact on ignition performance,a numerical model named the CBP evaluation(CBPE)was established in this paper to calculate the CBP of a *** CBPE model can be used to screen various potential breakdown paths to identify those that are most likely to satisfy the Townsend breakdown conditions,which are denoted as *** verify the calculation accuracy of the CBPE model,4.5 A-level HHC ignition tests were conducted on HHCs with three different *** comparing the test results and the calculated results of the breakdown voltage,the calculation errors of the CBPE under three HHC conditions ranged from 1.6%to 5.8%,and the trends of the calculated results were consistent with those of the test *** ignition test also showed the characteristics of the breakdown voltage curve and the ignition time for the three *** on the CBPE model,an in-depth analysis was conducted on the mechanism of the patterns revealed by the *** main conclusions are presented as follows:(1)the CBP always shifts from the long path to the short path in the HHCs with an increasing gas flow rate;and(2)the ignition time of the HHCs depends on the position of the CBP because different CBP positions can cause different mechanisms of heat transfer from the plasma to the *** study can guide the optimization of the CBP position and the corresponding ignition times of HHCs.

关键词： breakdown path heaterless hollow cathode breakdown voltage ignition time numerical calculation

Different oncological features of colorectal cancer codon-specific KRAS mutations:Not codon 13 but codon 12 have prognostic value

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World Journal of Gastroenterology 2023年第32期29卷 4883-4899页

作者： Hong-Min Ahn Duck-Woo Kim Tae Gyun lee Hye-rim Shin In Jun Yang Jeehye lee Jung Wook Suh Heung-Kwon Oh Sung-Bum Kang Department of Surgery Seoul National University Bundang HospitalSeongnam 13620South Korea Department of Pathology Seoul National University Bundang HospitalSeongnam 13620South Korea Department of Pathology Seoul National University HospitalSeoul 03080South Korea

BACKGROUND Approximately 40%of colorectal cancer(CRC)cases are linked to Kirsten rat sarcoma viral oncogene homolog(KRAS)*** mutations are associated with poor CRC prognosis,especially KRAS codon 12 mutation,which is associated with metastasis and poorer ***,the clinicopathological characteristics and prognosis of KRAS codon 13 mutation in CRC remain *** To evaluate the clinicopathological characteristics and prognostic value of codonspecific KRAS mutations,especially in codon *** This retrospective,single-center,observational cohort study included patients who underwent surgery for stage I-III CRC between January 2009 and December *** with KRAS mutation status confirmed by molecular pathology reports were *** relationships between clinicopathological characteristics and individual codon-specific KRAS mutations were *** data were analyzed to identify codon-specific KRAS mutations as recurrence-related factors using the Cox proportional hazards regression *** Among the 2203 patients,the incidence of KRAS codons 12,13,and 61 mutations was 27.7%,9.1%,and 1.3%,*** KARS codons 12 and 13 mutations showed a tendency to be associated with clinical characteristics,but only codon 12 was associated with pathological features,such as stage of primary tumor(T stage),lymph node involvement(N stage),vascular invasion,perineural invasion,tumor size,and microsatellite *** codon 13 mutation showed no associations(77.2%vs 85.3%,P=0.159),whereas codon 12 was associated with a lower 5-year recurrence-free survival rate(78.9%vs 75.5%,P=0.025).In multivariable analysis,along with T and N stages and vascular and perineural invasion,only codon 12(hazard ratio:1.399;95%confidence interval:1.034-1.894;P=0.030)among KRAS mutations was an independent risk factor for *** This study provides evidence that KRAS codon 13 mutation is less likely to serve as a prognostic biom

关键词： Genes Ras Codon Colonic neoplasms Rectal neoplasms

Delivery of nitric oxide-releasing silica nanoparticles for in vivo revascularization and functional recovery after acute peripheral nerve crush injury

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Neural Regeneration Research 2022年第9期17卷 2043-2049页

作者： Jung Il lee Ji Hun Park Yeong-rim Kim Kihak Gwon Hae Won Hwang Gayoung Jung Joo-yup lee Jeong-yun Sun Jong Woong Park Jae Ho Shin Myoung-Ryul Ok Department of Orthopedic Surgery College of MedicineKorea UniversitySeoulRepublic of Korea Medical Sensor Biomaterial Research Institute Kwangwoon UniversitySeoulRepublic of Korea Center for Biomaterials Korea Institute of Science&TechnologySeoulRepublic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoulRepublic of Korea Department of Orthopedic Surgery College of MedicineCatholic UniversitySeoulRepublic of Korea Department of Chemistry Kwangwoon UniversitySeoulRepublic of Korea

Nitric oxide(NO)has been shown to promote revascularization and nerve regeneration after peripheral nerve ***,in vivo application of NO remains challenging due to the lack of stable carrier materials capable of storing large amounts of NO molecules and releasing them on a clinically meaningful time ***,a silica nanoparticle system capable of reversible NO storage and release at a controlled and sustained rate was *** this study,NO-releasing silica nanoparticles(NO-SNs)were delivered to the peripheral nerves in rats after acute crush injury,mixed with natural hydrogel,to ensure the effective application of NO to the *** using a polymer dye and immunohistochemical staining for the detection of CD34(a marker for revascularization)results showed that NO-releasing silica nanoparticles increased revascularization at the crush site of the sciatic *** sciatic functional index revealed that there was a significant improvement in sciatic nerve function in NO-treated *** and anatomical analyses showed that the number of myelinated axons in the crushed sciatic nerve and wet muscle weight excised from NO-treated rats were ***,muscle function recovery was improved in rats treated with *** together,our results suggest that NO delivered to the injured sciatic nerve triggers enhanced revascularization at the lesion in the early phase after crushing injury,thereby promoting axonal regeneration and improving functional recovery.

关键词： crush injury nerve injury,nerve regeneration nitric oxide peripheral nerve revascularization silica nanoparticles

Mimetic Preparation of Analogues of Territrem B, A Potent Acetylcholinesterase Inhibitor

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Chinese Chemical Letters 2000年第12期11卷 1045-1048页

作者： yu ZHAO yuan Ling KU Shoei Sheng lee Laboratory of Phytochemistry Kunming Institute of BotanyChinese Academy of SciencesKunming 650204 School of Pharmacy College of MedicineNational Taiwan UniversityTaipei 10018

A mimetic synthesis of a potent acetylcholinesterase inhibitor, Territrem B, was carried out from the naturally occurring jujubosides. The anti-AChE activity of the product, which possesses the 2-en-1-one pharmacophore and the aromatic ring, was measured. The aromatic ring moiety seemed to be less influencing when comparing with the 2-en-1-one moiety.

关键词： acetylcholinesterase inhibitor territrem B analogues jujubosides

Preparation of AChE Inhibitors From Jujubogenin

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Chinese Chemical Letters 2000年第8期11卷 671-674页

作者： yu ZHAO yuan Ling KU Shoei Sheng lee Laboratory of Phytochemistry Kunnming Institute of BotanyChinese Academy of SciencesKunming 650204 School of Pharmacy College of MedicineNational Taiwan UniversityTaipei 10018

A dammarane derivative dihydrojujubogenin-2-en-1-one, which possesses a skeleton and pharmacophore partially similar to those of Territrem B, a potent AChE inhibitor, was synthesized via three different paths. The ant... 详细信息

关键词： Alzheimer disease (AD) acetylcholinesterase AChE inhibitor pharmaceutical chemistry jujubogenin Territrem B analogues

Tunable multiband terahertz metamaterials using a reconfigurable electric split-ring resonator array

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Light(Science & Applications) 2014年第1期3卷 211-218页

作者： Fusheng Ma yu-Sheng Lin Xinhai Zhang Chengkuo lee Department of Electrical and Computer Engineering National University of SingaporeSingapore 117576Singapore Institute of Materials Research and Engineering A*STARSingapore 117602Singapore

We demonstrate micromachined reconfigurable metamaterials working at multiple frequencies simultaneously in the terahertz *** proposed metamaterial structures can be structurally reconfigured by employing flexible microelectromechanical system-based cantilevers in the resonators,which are designed to deform out of plane under an external *** proposed metamaterial structures provide not only multiband resonance frequency operation but also polarization-dependent *** kinds of metamaterials are investigated as electric split-ring resonator(eSRR)arrays with different positions of the *** moving the position of the split away from the resonator’s center,the eSRR exhibits anisotropy,with the dipole resonance splitting into two *** dipole–dipole coupling strength can be continuously adjusted,which enables the electromagnetic response to be tailored by adjusting the direct current(DC)voltage between the released cantilevers and the silicon *** observed tunability of the eSRRs is found to be dependent on the polarization of the incident terahertz *** polarization-dependent tunability is demonstrated by both experimental measurements and electromagnetic simulations.

关键词： MEMS reconfigurable metamaterials split-ring resonator terahertz tunability