Focused ion beam-induced displacive phase transformation from austenite to martensite during fabrication of quenched and partitioned steel micro-pillar

We report evidence of a displacive phase transformation from retained austenite to martensite during preparation of quenched and partitioned steel micro-pillars by using a focused ion beam (FIB) technique. The BCC phase produced by the FIB damage was identified as martensite. The invariant-plane strain surface relief associated with the martensitic transformation was observed in the retained austenite phase immediately after a FIB scan of the surface with the Ga+ ion beam. Use of a low acceleration voltage appears to lower the probability of the phase transformation, while a decrease of the acceleration voltage will result in an increase of the total milling time required to prepare a micro-pillar. This report addresses challenges related to the preparation of austenite micro-pillars by a conventional FIB technique. Published by Elsevier B.V

Multi-responsive albumin-lonidamine conjugated hybridized gold nanoparticle as a combined photothermal-chemotherapy for synergistic tumor ablation

Herein, we developed a multifunctional nanoplatform based on the nanoassembly of gold nanoparticles (GNP) conjugated with lonidamine (LND) and aptamer AS1411 (AS-LAGN) as an effective cancer treatment. Conjugating AS1411 aptamer on the surface of the nanoparticle significantly improved particle accumulation in cancer cells via specific affinity toward the nucleolin receptors. In vitro study clearly revealed that laser irradiation-based hyperthermia effect enhanced the chemotherapeutic effects of LND. Combinational treatment modalities revealed significant apoptosis with higher cell killing effect due to increased ROS production and inhibition of cell migration. GNP's ability to convert the excited state photon energy into thermal heat enabled synergistic photothermal/chemotherapy with improved therapeutic efficacy in animal models. Moreover, immunohistochemistry staining assays confirmed the ability of ASLAGN to induce cellular apoptosis/necrosis and ablation in tumor tissues, without causing evident damages to the surrounding healthy tissues. Altogether, this AS-LAGN nanoplatform could be a promising strategy for mitochondria-based cancer treatment. Statement of significance We have designed a facile biodegradable multifunctional nanocarrier system to target the mitochondria, the major "power house" of the cancer cells. We have constructed a multifunctional nanoassembly of protein coronated gold nanoparticles (GNP) conjugated with lonidamine (LND) and aptamer AS1411 (ASLAGN) as an effective combination of phototherapy with chemotherapy for cancer treatment. The LND was conjugated with albumin which was in turn conjugated to GNP via redox-liable disulfide linkage to generate oxidative stress and ROS to kill cancer cells. GNP's ability to convert the excited state photon energy into thermal heat enabled synergistic photothermal/chemotherapy with improved therapeutic efficacy in animal models. Consistently, AS-LAGN showed enhanced antitumor efficacy in xenograft tumor model with remarkable tumor regression property. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.This research was supported by a grant from the National Research Foundation of Korea (NRF), funded by the Korea government (MSIP) (No. 2018R1A2A2A05021143 and 2018R1D1A1A02085586), and by the Medical Research Center Program (2015R1A5A2009124 and 2018R1A5A2025272) through the NRF funded by MSIP

From civic to citizenship education: Toward a stronger citizenship orientation in the Ethiopian CEE curriculum

Recent research on Civic and Ethical Education (CEE) in Ethiopia has revealed a need for improvement in a number of areas with regard to the current CEE curricula. These materials are currently oriented to a conservative form of civic education than on citizenship education, whose aims are more progressive. The essential problem identified in the present study is that CEE content does not match the Ethiopian Ministry of Education’s stated goals for CEE, including the promotion of global citizenship. An inductive method was used to categorize themes found in the CEE curricula and textbook, which were analyzed with reference to Tawil’s (2013) framework for education for global citizenship. A concept in textual analysis known as ‘internal critique’ was also utilized to identify inconsistencies in the materials between the stated aims of the CEE program and the textbook content itself. The analysis revealed three main characteristics of the CEE textbooks, namely, an emphasis on sovereignty, patriotism, and responsibility; ambivalence to Ethiopia’s independence from/dependence on wealthier nations, and abstraction in CEE content. This content does only partially match the Ethiopian government’s stated aims for CEE. The findings of this study suggest that the content of the ethical dimension of Ethiopia’s CEE curriculum could be greatly improved through the inclusion of content that reflects an emphasis on citizenship education. Such an approach is more progressive than civic education and promotes a more learner-centered and critical orientation to ethical issues on the part of students within the framework of Global Citizenship Education (GCE)

Numerical simulation of a multi-port differential mobility analyzer(MP-DMA) used in a real-time nano-particle sizer (NPS)

In a recently conducted study, we developed a nano-particle sizer (NPS) that consists of a multi-port differential mobility analyzer (MP-DMA) and two multi condensation particle counters (M-CPCs) for achieving fast measurements of aerosol particles; however, the performance of MP-DMA was not detailed in the study. Therefore, the objective of this study is to perform numerical simulations to obtain the transfer function of each port in the MP-DMA, which is the main component of the NPS. We observed good agreement between the numerically obtained central particle size of each port and the experimental data under the same operating conditions. The transmission probability and resolution of each port were determined and analyzed under various conditions using the transfer function. The findings of this study shall help in understanding the advantages of NPS.This work was supported by the research fund of Hanyang University (HY-2019-P)

Extensive evaluation and classification of low‐cost dust sensors in laboratory using a newly developed test method

An extensive evaluation of low-cost dust sensors was performed using an exponentially decaying particle concentration. A total of 264 sensors including 27 sensors with light-emitting diodes (LEDs) and 237 sensors with laser lighting sources were tested. Those tested sensors were classified into 4 groups based on the deviation from the reference data obtained by a reference instrument. The response linearities of all the tested samples for PM1, PM2.5, and PM10 were in excellent agreement with the reference instrument, except a few samples. For the measurements of PM1 and PM2.5, the lighting source, that is, LED or laser, did not show any significant difference in overall sensor performance. However, LED-based sensors did not perform well for PM10 measurements. The 32, 24, and 16% of all the tested sensors for PM1, PM2.5, and PM10 measurement, respectively, are in the category of Class 1 (reference instrument reading +/- 20%) requirement. The performance of the low-cost dust sensors for PM10 measurement was relatively less satisfactory.The Ministry of Trade, Industry & Energy (MOTIE, Korea)

Ultrathin WO3 Nanosheets Converted from Metallic WS2 Sheets by Spontaneous Formation and Deposition of PdO Nanoclusters for Visible Light-Driven C−C Coupling Reactions

It is not facile to obtain ultrathin two-dimensional (2D) WO3 nanosheets through the exfoliation of their bulk counterpart in solution due to strong covalent interaction between interlayers. In addition, they require additional functionalization with cocatalysts to expand their applicability in photocatalytic organic reactions owing to their insufficient conduction band edge position. Here, we report a chemical approach for the simultaneous production and functionalization of ultrathin 2D WO3 nanosheets through the direct conversion of metallic WS2 nanosheets, accomplished by the spontaneous formation and deposition of PdO nanoclusters on the nanosheet surface in H2O. When chemically exfoliated metallic WS2 nanosheets were simply mixed with K2PdCl4 in H2O under mild conditions (50 degrees C, 1 h), they were converted to semiconducting WO3 nanosheets on which PdO nanoclusters of a uniform size (similar to 3 nm) were spontaneously formed, leading to the production of PdO-functionalized ultrathin WO3 (PdO@WO3) nanohybrids. The conversion yield of WO3 nanosheets from metallic WS2 nanosheets increased with increasing coverage of PdO nanoclusters on the nanosheet surface. In addition, the conversion of WO3 nanosheets induced by PdO nanocluster formation was effective only in H2O but not in organic solvents, such as N-methylpyrrolidone and acetonitrile. A mechanical study suggests that the chemisorption of hydrated Pd precursors on the chalcogens of metallic WS2 nanosheets leads to their facile oxidation by water molecules, producing WO3 nanosheets covered with PdO nanoclusters. The as-prepared PdO@WO3 nanosheets exhibited excellent photocatalytic activity and recyclability in Suzuki cross-coupling reactions of various aryl halides under visible light irradiation.This work was supported by the Basic Science Research Program (NRF-2014R1A2A1A11051877 and NRF-2017R1A2B2008455) through the National Research Foundation of Korea funded by the Ministry of Science and ICT

Sulfuric Acid Resistance Evaluation of Repair Mortar Substituted Blast Furnace

The Reinforced concrete structure is deteriorated in durability due to various deterioration factors such as acid, salt, etc., and thus requires repair and reinforcement. In this study, compressive strength and weight change were measured by substituting blast furnace slag with excellent chemical resistance. As a result, the decrease in compressive strength decreased in proportion to the blast furnace slag substitution rate, and in the case of BFS40, the strength increased after sulfuric acid immersion. The weight change also decreased in proportion to the replacement amount

Nonlinear dynamic modeling and response analysis of a rotor-blade system with whirling motion

In this paper, we propose a new nonlinear dynamic model of a rotor-blade system with whirling motion, in which a rigid rotor and blades are modeled as a Jeffcott rotor and Euler-Bernoulli beams, respectively. The stiffening effects of the rotating blades are considered using a hybrid set of deformations, which consist of the stretch and chordwise deformations. After the nonlinear partial differential equations of motion are derived using Hamilton's principle, they are discretized using the Galerkin method. From the discretized equations, the nonlinear dynamic responses are computed using the generalized-alpha time integration method. Based on the dynamic responses and the frequency spectra, the proposed model is verified both for the case where the blade is considered to be a rigid body and for the case where there is no whirling motion of the rotor. In this study, the nonlinear dynamic responses of the rotor-blade system are analyzed in terms of the natural frequencies for whirling motion and the natural frequencies of the deformation of the rotating beam. In addition, the effects of the supporting stiffness, rotating speed and blade stiffness on the dynamic responses of the radial displacement and stretch/chordwise deformations are also analyzed

Effect of Curing Condition on the Chloride ion Diffusion Coefficient in Concrete with GGBFS

양생조건이 GGBFS를 사용한 시멘트 콘크리트의 염화물이온 확산계수에 미치는 영향에 대한 연구를 진행하였다. 양생조건은 기중양생 (20±2℃, RH 60±5%)과 수중 양생 (20±2℃)으로 구분하였으며, GGBFS 치환율은 0%(대조군), 30%, 60%로 구분하여 3가지 배합의 콘크리트를 W/B 40%, 50%, 60%로 구분하여 제작하였다. 시험은 콘크리트 압축강도평가, 염화물이온확산계수 평가를 실시하였다. 콘크리트의 압축강도는 GGBFS 치환율이 증가할수록 수중양생 대비 기중양생 시험체의 압축강도의 발현율이 감소하였다. 염화물이온확산계수 측정결과 GGBFS치환율이 증가할수록 염화물이온 확산계수가 감소하였지만, 수중 양생대비 기중양생 시험체의 콘크리트 염화물이온 확산계수는 증가하여 최대 111%까지 증가하는 것을 확인하였다. The changes in the resistance to chloride ingress of concrete using a ground granulated blast furnace slag (GGBFS) according to curing conditions were examined. The curing conditions were divided in air-dry curing and under-water curing. Three concrete mixures with the GGBFS replacement ratio of 0%(control), 30%, and 60% were prepared. For tests, evaluations of concrete compressive strength, and chloride ion diffusion coefficient were performed. As the GGBFS replacement ratio increased, the concrete compressive strength of the in air-dry cured specimens decreased compared to under-water cured specimens. When the chloride ion diffusion coefficient was measured, the chloride ion diffusion coefficient decreased as the GGBFS replacement ratio increased. However, the diffusion coefficient of the in air-dry cured specimen was increased up to 111% compared with the under-water cured specime

Lobar evenness of deposition/retention in rat lungs of inhaled silver nanoparticles: an approach for reducing animal use while maximizing endpoints

BackgroundInformation on particle deposition, retention and clearance are important for the evaluation of the risk of inhaled nanomaterials to human health. Recent revised OECD inhalation toxicity test guidelines require to evaluate the lung burden of nanomaterials after rodent subacute and subchronic inhalation exposure (OECD 412, OECD 413). These revised test guidelines require additional post-exposure observation (PEO) periods that include lung burden measurements that can inform on lung clearance behavior and translocation. The latter being particularly relevant when the testing chemical is a solid poorly soluble nanomaterial. Therefore, in the spirit of 3 R's, we investigated whether measurement of retained lung burden of inhaled nanoparticles (NPs) in individual lung lobes is sufficient to determine retained lung burden in the total lung. If it is possible to use only one lobe, it will reduce animal use and maximize the number of endpoints evaluated.ResultsTo achieve these goals, rats were exposed nose-only for 1 or 5days (6h/day) to an aerosol of 20nm well-dispersed silver nanoparticles (AgNPs), which is the desired particle diameter resulting in maximum deposition in the pulmonary region when inhaled as singlets. After exposure, the five lung lobes were separated and silver concentration was measured using inductively coupled plasma-mass spectrophotometer (ICP-MS). The results showed that the retention of deposited silver nanoparticle in the different lung lobes did not show any statistically significant difference among lung lobes in terms of silver mass per gram lung lobe. This novel finding of evenness of retention/deposition of inhaled 20nm NPs in rats for all five lobes in terms of mass per unit tissue weight contrasts with earlier studies reporting greater apical lobe deposition of inhaled micro-particles in rodents. The difference is most likely due to preferred and efficient deposition of inhaled NPs by diffusion vs. additional deposition by sedimentation and impaction for micron-sized particles.ConclusionAgNPs following acute inhalation by rats are evenly retained in each lung lobe in terms of mass per unit lung tissue weight. Accordingly, we suggest sampling any of the rat lung lobes for lung burden analysis can be used to determine deposited or retained total lung burden after short-term inhalation of NPs and using the other lobes for collecting and analyzing bronchoalveolar lavage fluid (BALF) and for histopathological analysis. Therefore, by combining lung burden measurement, histopathological tissue preparation, and BALF assay in the same rat will reduce the number of animals used and maximize the number of endpoints measured.This research was supported by the Industrial Technology Innovation Program (10052901), Development of highly usable nanomaterial inhalation toxicity testing system in commerce through the Korea Evaluation Institute of Industrial Technology by the Korean Ministry of Trade, Industry & Energy and NIH/NIEHS grants U19ES019545, P30ES007033 and EPA grant RD83573801