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Amorphous-Phase-Mediated Crystallization of Ni Nanocrystals Revealed by High-Resolution Liquid-Phase Electron Microscopy
No full textNonclassical features of crystallization in solution have been recently identified both experimentally and theoretically. In particular, an amorphous-phase-mediated pathway is found in various crystallization systems as an important route, different from the classical nucleation and growth model. Here, we utilize high-resolution in situ transmission electron microscopy with graphene liquid cells to study amorphous-phase-mediated formation of Ni nanocrystals. An amorphous phase is precipitated in the initial stage of the reaction. Within the amorphous particles, crystalline domains nucleate and eventually form nanocrystals. In addition, unique crystallization behaviors, such as formation of multiple domains and dislocation relaxation, are observed in amorphous-phase-mediated crystallization. Theoretical calculations confirm that surface interactions can induce amorphous precipitation of metal precursors, which is analogous to the surface-induced amorphous-to-crystalline transformation occurring in biomineralization. Our results imply that an unexplored nonclassical growth mechanism is important for the formation of nanocrystals.This work was supported by IBS-R006-D1 (T.H. and J.P.); the National Research Foundation (NRF) of Korea, funded by the Korea government (MSIT) (No. NRF-2017R1C1B2010434 and No. NRF-2017R1A5A1015365) (J.P.); the MOTIE (Ministry of Trade, Industry & Energy) and KRSC (Korea Semiconductor Research Consortium) support program for the development of future semiconductor devices (No. 10080657) (J.P.); and the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract No. DE-AC02-05CH11231 within the KC22ZH program (J.Y. and P.E.). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. DOE under Contract No. DE-AC02-05CH11231. The Institute of Engineering Research at Seoul National University provided research facilities for this work. This work was also supported by the Basic Science Research Program (No. NRF-2018R1D1A1B07046751) through the NRF of Korea, funded by the Ministry of Education, Science and Technology O.K. and H.L.); the Supercomputing Center/Korea Institute of Science and Technology Information with supercomputing resources including technical support (KSC-2018-C2-0024) (S.K. and W.B.L.); the Basic Science Research Programs through the NRF of Korea funded by the Ministry of Science and ICT (2016R1C1B1014940); and the Ministry of Education (2018R1D1A1B07050575) (J.S. and W.C.L.)
Near infrared light-responsive heat-emitting hemoglobin hydrogels for photothermal cancer therapy
No full textPhotothermal therapy (PTT) is an effective means of treating tumors because tumor cells are sensitive to heat. Gold and carbon nanoparticles are used as efficient PTT materials. However, development of a non-toxic biodegradable PTT agent remains a challenge. Here, we developed a hemoglobin (Hb) hydrogel that exhibited excellent PTT effects in vitro and in vivo. Unlike conventional PTT agents, which are toxic and do not decompose completely in the body, the Hb hydrogel was manufactured using only two components: (i) Hb, a natural substance derived from the human body, and (ii) PEG, an FDA-approved polymer. The gelation time of the Hb hydrogels could be controlled by changing the Hb concentration. Because Hb is present at a high concentration (150 mg/ml) in the body, the Hb hydrogel decomposed and was eliminated in vivo without toxicity. The Hb hydrogel showed an excellent PTT effect in response to 808 nm near-infrared (NIR) laser irradiation and had excellent anticancer effects against A549 lung cancer cells both in vitro and in vivo. Blood hematology and blood biochemical assay results from an animal model treated with Hb hydrogel were similar to those of the control group. Importantly, toxicity was not observed based on H&E staining of major organs (heart, liver, spleen, kidneys and lung). Tumors of A549 cell-xenografted mice treated with Hb hydrogel and 808 run NIR laser irradiation were significantly smaller than those of the control group (23.1 mm(3.) versus 746.5 mm(3), respectively). This is a first report of a biocompatible photothermal hydrogel based on hemoglobin, and our overall results suggest that Hb hydrogels are commercially-promising PTT systems that have excellent anti-cancer effects.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017R1A2B2004955)
Chlorella-gold nanorods hydrogels generating photosynthesis-derived oxygen and mild heat for the treatment of hypoxic breast cancer
No full textHypoxic tumors are rarely cured because their low oxygen environment restricts the cytotoxicity of many chemotherapeutics by blocking the production of intracellular reactive oxygen species. Inspired by the highly efficient production of oxygen as a waste product of chlorella photosynthesis, we developed an in situ rapidly gelling BSA-PEG-based hydrogel depot system that contains chlorella and gold nanorods, namely Chlorella AuNRs BSA-Gel. The entrapped chlorella in our gel efficiently generated a high level of oxygen and oxygenated hemoglobin via photosynthesis in response to 660-nm light in vitro and in vivo, respectively. The incorporated gold nanorods showed excellent performance in precisely increasing the surrounding temperature to 41-42 degrees C responding to 808-nm near-infrared laser, which presumably played a supporting role in expanding the tumor vasculature and thereby facilitating the delivery of doxorubicin and oxygen to hypoxic tumors of mice. Our results showed that a combined therapy of Chlorella AuNRs BSA-Gel plus Dox followed by irradiation at 660 nm and 808 nm significantly abolished 4T1 breast cancer cell-xenografted tumors of BALB/C mice. We believe that our oxygen-generating and mild heat-emitting hydrogel should be considered to be a valid prototype of a local depot system for treatment of hypoxic tumors.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017R1A2B2004955)
Rational combination immunotherapeutic approaches for effective cancer treatment
No full textImmunotherapy is an important mode of cancer treatment. Over the past decades, immunotherapy has improved the clinical outcome for cancer patients. However, in many cases, mutations in cancer cells, lack of selectivity, insufficiency of tumor-reactive T cells, and host immunosuppression limit the clinical benefit of immunotherapy. Combination approaches in immunotherapy may overcome these obstacles. Accumulating evidence demonstrates that combination immunotherapy is the future of cancer treatment. However, designing safe and rational combinations of immunotherapy with other treatment modalities is critical. This review will discuss the optimal immunotherapy-based combinations mainly with respect to the mechanisms of action of individual therapeutic agents that target multiple steps in evasion and progression of tumor.This research was supported by a grant from the National Research Foundation of Korea (NRF), funded by the Korea government (MSIP) (No. 2018R1A2A2A05021143) and by the Medical Research Center Program (2015R1A5A2009124) through the NRF funded by MSIP
Perceptual Cues for the Word-Initial Nasal Stops in Korean
No full text본 연구는 비음과 모음 연결구간이 한국어 비자음을 인식하는데 기여하는 역할에 대해 연구하였다. 긴 비음 [ㄴ]과 짧은 비음 [ㄴ], 그리고 모음 [우]/[아]가 사용된 자연발화를 이용하여 세가지 타입(비성자질, 모음연결구간, 전체음절)의 음성테스트 시료를 만들었다. 실험결과에 따르면, 긴 비성자질과는 달리 짧은 비성자질은 비자음으로 인식되는 자질로는 약하다는 사실이 발견되었다. 짧은 비성자질은 폐쇄음으로 인식되기도 했다. 반면에, 긴 비성자질 뒤의 모음 [아]보다는 짧은 비성자질 뒤의 모음 [아]에서 비자음 [ㄴ]이 더 많이 인식되었다. 우리는 이런 현상이 비성자질과 연결모음구간의 상대적 돋들림에 의한 상호 보완작용 때문이라고 주장한다. 또한 이 논문은 [아] 모음 연결구간이 [우] 모음 연결구간과는 다른 인식결과를 도출하였다는 것을 보여주었다. 앞으로의 연구에서는 한국어의 다양한 비음과 모음과의 결합을 연구하려고 한다.
This study investigated the role of the nasal murmur and vowel transitions as perceptual cues for Korean nasals. Three types of stimuli (murmur, vowel transition, and whole syllable) were generated from natural utterances of [n] with long vs. short murmur plus [u]/[a]. The results of the identification test showed that unlike the long murmur, the short murmur provides a weak perceptual cue for nasality. The short murmur could lead to the perception of nasals as voiced plosives. In contrast, more correct nasals responses were induced from the vowel [a] following the short murmur type rather than from the vowel [a] following the long murmur type. We suggest that there is the reciprocal relationship in perception between the relative salience of murmur and vowel transition. In this paper, we also showed that transition to vowel /a/ induced different perceptual results from transition to vowel /u/ did. In the future study, we will investigate a wide variety of nasals and the following vowel types to understand the full spectrum of the nasal-vowel sequence in Korean
Evidence for moire excitons in van der Waals heterostructures
No full textRecent advances in the isolation and stacking of monolayers of van der Waals materials have provided approaches for the preparation of quantum materials in the ultimate two-dimensional limit(1,2). In van der Waals heterostructures formed by stacking two monolayer semiconductors, lattice mismatch or rotational misalignment introduces an in-plane moire superlattice(3). It is widely recognized that the moire superlattice can modulate the electronic band structure of the material and lead to transport properties such as unconventional superconductivity(4) and insulating behaviour driven by correlations(5-7); however, the influence of the moire superlattice on optical properties has not been investigated experimentally. Here we report the observation of multiple interlayer exciton resonances with either positive or negative circularly polarized emission in a molybdenum diselenide/tungsten diselenide (MoSe2/WSe2) heterobilayer with a small twist angle. We attribute these resonances to excitonic ground and excited states confined within the moire potential. This interpretation is supported by recombination dynamics and by the dependence of these interlayer exciton resonances on twist angle and temperature. These results suggest the feasibility of engineering artificial excitonic crystals using van der Waals heterostructures for nanophotonics and quantum information applications.The work performed by K.T., J.C., A.H.M. and X. Li was primarily supported by the National Science Foundation (NSF) through the Center for Dynamics and Control of Materials, an NSF MRSEC, under Cooperative Agreement DMR-1720595. X. Li also acknowledges partial support from NSF EFMA-1542747 and the Welch Foundation via grant F-1662. The theoretical work by F.W. was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. J.Q acknowledges support from the China Scholarship Council (grant 201706050068). A.H.M., K.K. and E.T. were supported in part by Army Research Office (ARO) grant W911NF-17-1-0312 (MURI). X. Lu and L.Y. are supported by the Air Force Office of Scientific Research (AFOSR) FA9550-17-1-0304 and NSF DMR-1455346. S.K. was financially supported by National Research Foundation of Korea (NRF) grant funded by the South Korean government (2017R1D1B04036381). K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and JSPS KAKENHI grant JP15K21722. A.R. and S.K.B. acknowledge support from the NASCENT Engineering Research Centre (ERC) funded by NSF grant EEC-1160494. D.A.S acknowledges support from the NSF Graduate Research Fellowship Program. N.L. acknowledges support from NSF CMMI-1351875. The Texas Nanofabrication Facility, where some of the work was carried out, is a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the NSF (grant ECCS-1542159). This work is an official contribution of NIST, which is not subject to copyright in the United States
Structural Breaks : A Shift of Roles in the Relationship between Real Estate Regional Industry
No full textWe conduct an analysis of connectivity between regional housing markets and regional industry by examining 10 consolidated metropolitan statistical areas (CMSAs) in the Case-Shiller Index and stock portfolios representing the economic base for each region. We test for cointegrating relationships between real estate markets and industry performance and find that, prior to the recent real estate market collapse, prices in the housing market are dependent on industry performance; post-collapse, however, this relationship changes. Our results suggest that the recent financial crisis was so severe that it resulted in a structural break in the causal relationship between regional industry performance and real estate markets
Transferrin-Conjugated Polymeric Nanoparticle for Receptor-Mediated Delivery of Doxorubicin in Doxorubicin-Resistant Breast Cancer Cells
No full textIn this study, a transferrin (T-f)-conjugated polymeric nanoparticle was developed for the targeted delivery of the chemotherapeutic agent doxorubicin (Dox) in order to overcome multi-drug resistance in cancer treatment. Our objective was to improve Dox delivery for producing significant antitumor efficacy in Dox-resistant (R) breast cancer cell lines with minimum toxicity to healthy cells. The results of our experiments revealed that Dox was successfully loaded inside a transferrin (T-f)-conjugated polymeric nanoparticle composed of poloxamer 407 (F127) and 123 (P123) (Dox/F127&P123-T-f), which produced nanosized particles (similar to 90 nm) with a low polydispersity index (similar to 0.23). The accelerated and controlled release profiles of Dox from the nanoparticles were characterized in acidic and physiological pH and Dox/F127&P123-T-f enhanced Dox cytotoxicity in OVCAR-3, MDA-MB-231, and MDA-MB-231(R) cell lines through induction of cellular apoptosis. Moreover, Dox/F127&P123-T-f inhibited cell migration and altered the cell cycle patterns of different cancer cells. In vivo study in MDA-MB-231(R) tumor-bearing mice demonstrated enhanced delivery of nanoparticles to the tumor site when coated in a targeting moiety. Therefore, Dox/F127&P123-T-f has been tailored, using the principles of nanotherapeutics, to overcome drug-resistant chemotherapy.This research was supported by a National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2018R1A2A2A05021143), and by the Medical Research Center Program (2018R1A5A2025272) through the NRF, funded by MSIP
Assessment of Game player’s performance and cognitive load depending on the frame rate change
No full textUnderstanding Wake-Up Tasks in Mobile Alarm App
No full text최근 모바일 알람 앱들은 수학문제 풀기, 인증사진 찍기, 기기 흔들기와 같은 기상 과업(Wake-Up Task)을 수행해야 알람이 해제되는 독특한 알람 해제 방법을 제공하고 있다. 기상 과업이 주는 신체적, 인지적 부하에도 불구하고 많은 사용자들이 매일 아침 기상과업을 기꺼이 사용하고 있으며, 이와 같은 현상은 불편한 상호작용(Inconvenient Interaction)의 실증적 사례로 볼 수 있다. 본 논문은 모바일 알람 앱 ‘알라미(Alarmy)’ 사용 데이터를 분석하여 기상 과업 별알람 앱 사용 행동을 비교해 보고, 비교 결과를 바탕으로 사람을 깨우기 위한 불편한 상호작용 원리에 대해 논의한다