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Purpose Acute promyelocytic leukemia (APL) is a rare disease in children and there are some different characteristics between children and adult. We aimed to evaluate incidence, clinical characteristics and treatment outcomes of pediatric APL in Korea.Materials and Methods Seventy-nine pediatric APL patients diagnosed from January 2009 to December 2016 in 16 tertiary medical centers in Korea were reviewed retrospectively.Results Of 801 acute myeloid leukemia children, 79 (9.9%) were diagnosed with APL. The median age at diagnosis was 10.6 years (range, 1.3 to 18.0). Male and female ratio was 1:0.93. Thirty patients (38.0%) had white blood cell (WBC) count greater than 10×109/L at diagnosis. All patients received induction therapy consisting of all-trans retinoic acid and chemotherapy. Five patients (6.6%) died during induction chemotherapy and 66 patients (86.8%) achieved complete remission (CR) after induction chemotherapy. The causes of death were three intracranial hemorrhage, one cerebral infarction, and one sepsis. Five patients (7.1%) suffered a relapse during or after maintenance chemotherapy. The estimated 4-year event-free survival and overall survival (OS) rates were 82.1%±4.4%, 89.7%±5.1%, respectively. The 4-year OS was significantly higher in patients with initial WBC < 10×109/L than in those with initial WBC ≥ 10×109/L (p=0.020).Conclusion This study showed that the CR rates and survival outcomes in Korean pediatric APL patients were relatively good. The initial WBC count was the most important prognostic factor and most causes of death were related to serious bleeding in the early stage of treatment.

A 3D co-continuous polymer nanocomposite with high strength and high recoverability is demonstrated. This nanocomposite used hard-core-soft-matrix design which is suitable for obtaining the optimal strength. Polyvinyl alcohol (PVA) was freeze-dried together with silver nanowires (AgNW) to fabricate a 3D porous structure as hard-core phase, which was then filled with polydimethylsiloxane (PDMS) as soft-matrix phase via vacuum infiltration. The PVA + AgNW nanocomposite served as the hard core, with PDMS as the soft matrix, with this hard core-soft matrix design allowing for a combination of the excellent strength of the nanocomposite and the resilience of the PDMS. The addition of AgNWs strengthened the modulus of the freeze-dried structure over the 3 times and the comparison with the Halpin-Tsai model is indicated of AgNWs were well dispersed into the wall of the 3D structure. The vertical pore alignment of the freeze-dried structure resulted in an increased the strength. In addition, incorporation of hard core-soft matrix significantly increased the strength of the 3D nanocomposite up to 3.5 times that of the PDMS as a result of the co-continuous incorporation of hard and soft phases with well distributed 3D interfaces that also hindered crack propagation. Therefore, the PVA + AgNW 3D porous structure contributed by strengthening and toughening of the entire composite, resulting in increasing energy loss coefficients of nanocomposites, which showed good shock absorbance.

Information on sex differences in the association between chronotype and depression is scarce. We aimed to investigate these differences using data from the Korea National Health and Nutrition Examination Survey in 2016. Chronotypes were categorised based on mid-sleep time on free days corrected by sleep debt accumulated on workdays (MSFsc): early type, mean MSFsc + 1 SD. A Patient Health Questionnaire-9 score of ≥ 10 indicated depression. Among 5550 non-shift working adults aged 19–80 years, the prevalence rates of depression in the early, intermediate, and late chronotype groups were 7.4%, 4.5%, and 9.3%, respectively. Women with late chronotype (odds ratio [OR] = 2.9, 95% confidence interval [CI] = 1.8–4.7) showed a higher risk of depression than women with intermediate chronotype after adjusting for covariates. Women with early chronotype did not show a significant difference in depression risk (OR = 1.3, 95% CI = 0.9–2.0). In conclusion, late chronotype is associated with an increased risk of depression in women but not in men. Early chronotype is not associated with depression in women or men.

Background There has been growing international interest in performing remote consultations in primary care, particularly amidst the current COVID-19 pandemic. Despite this, the evidence surrounding the safety of remote consultations is inconclusive. The appropriateness of antibiotic prescribing in remote consultations is an important aspect of patient safety that needs to be addressed. Objective This study aimed to summarize evidence on the impact of remote consultation in primary care with regard to antibiotic prescribing. Methods Searches were conducted in MEDLINE, Embase, HMIC, PsycINFO, and CINAHL for literature published since the databases’ inception to February 2020. Peer-reviewed studies conducted in primary health care settings were included. All remote consultation types were considered, and studies were required to report any quantitative measure of antibiotic prescribing to be included in this systematic review. Studies were excluded if there were no comparison groups (face-to-face consultations). Results In total, 12 studies were identified. Of these, 4 studies reported higher antibiotic-prescribing rates, 5 studies reported lower antibiotic-prescribing rates, and 3 studies reported similar antibiotic-prescribing rates in remote consultations compared with face-to-face consultations. Guideline-concordant prescribing was not significantly different between remote and face-to-face consultations for patients with sinusitis, but conflicting results were found for patients with acute respiratory infections. Mixed evidence was found for follow-up visit rates after remote and face-to-face consultations. Conclusions There is insufficient evidence to confidently conclude that remote consulting has a significant impact on antibiotic prescribing in primary care. However, studies indicating higher prescribing rates in remote consultations than in face-to-face consultations are a concern. Further, well-conducted studies are needed to inform safe and appropriate implementation of remote consulting to ensure that there is no unintended impact on antimicrobial resistance.

Background: Cutaneous allodynia (CA) is a common feature of migraine and a clinical marker of central sensitization. Probable migraine (PM) is a subtype of migraine that fulfils all but one criterion of migraine. The present study aimed to evaluate the prevalence and characteristics of CA and those of migraine in PM. Methods: We used the data of the Korean Sleep-Headache study, which was a nation-wide population-based study on headache and sleep. CA was evaluated using the Allodynia Symptom Checklist-12 (ASC-12) questionnaire with ASC-12 score ≥ 3 classified as CA. Results: Of 2501 participants, the prevalence of migraine and PM were 5.0% and 11.6%, respectively. The prevalence of CA did not significantly differ between migraine and PM (16.0% vs. 14.5%, respectively, p = 0.701). Individuals with PM with CA reported a higher monthly frequency of headache (3.3 ± 4.3 vs. 1.8 ± 3.6, respectively, p = 0.044), more severe intensity of headache (Visuals Analogue Scale, median and interquartile range, 6.0 [4.0–7.0] vs. 5.0 [3.0–6.0], respectively, p = 0.002), and higher impact of headache (Headache Impact Test-6, 56.3 ± 7.2 vs. 48.3 ± 8.0, respectively, p < 0.001) and disability (Migraine Disability Assessment, 1.00 [0.00–10.00] vs. 0.00 [0.00–1.00], respectively, p < 0.001) than individuals with PM without CA. Multiple regression analyses revealed that the frequency and intensity of headache, anxiety, and depression were significant factors of CA in individuals with PM. Conclusions: Approximately one-sixth of individuals with migraine and PM experienced CA in a representative sample of Korea. Anxiety, depression, and high frequency of headaches were significant factors of CA in individuals with PM.

BACKGROUND There has been growing international interest in performing remote consultations in primary care, particularly amidst the current COVID-19 pandemic. Despite this, the evidence surrounding the safety of remote consultations is inconclusive. The appropriateness of antibiotic prescribing in remote consultations is an important aspect of patient safety that needs to be addressed. OBJECTIVE This study aimed to summarize evidence on the impact of remote consultation in primary care with regard to antibiotic prescribing. METHODS Searches were conducted in MEDLINE, Embase, HMIC, PsycINFO, and CINAHL for literature published since the databases’ inception to February 2020. Peer-reviewed studies conducted in primary health care settings were included. All remote consultation types were considered, and studies were required to report any quantitative measure of antibiotic prescribing to be included in this systematic review. Studies were excluded if there were no comparison groups (face-to-face consultations). RESULTS In total, 12 studies were identified. Of these, 4 studies reported higher antibiotic-prescribing rates, 5 studies reported lower antibiotic-prescribing rates, and 3 studies reported similar antibiotic-prescribing rates in remote consultations compared with face-to-face consultations. Guideline-concordant prescribing was not significantly different between remote and face-to-face consultations for patients with sinusitis, but conflicting results were found for patients with acute respiratory infections. Mixed evidence was found for follow-up visit rates after remote and face-to-face consultations. CONCLUSIONS There is insufficient evidence to confidently conclude that remote consulting has a significant impact on antibiotic prescribing in primary care. However, studies indicating higher prescribing rates in remote consultations than in face-to-face consultations are a concern. Further, well-conducted studies are needed to inform safe and appropriate implementation of remote consulting to ensure that there is no unintended impact on antimicrobial resistance.

Purpose Nasal pain, as an epileptic aura, has been poorly recognized. This study aims to demonstrate clinical features of patients with epilepsy who have nasal pain as an aura. Methods We retrospectively investigated consecutive patients who visited the epilepsy clinic of tertiary hospital from April 2000 to September 2019. All included patients underwent epilepsy-dedicated, high-resolution magnetic resonance imaging (MRI) examinations. All MRI studies were analyzed by visual inspection. Results Seven patients who presented nasal pain as an aura, were identified. Four patients reported nasal pain as the first aura. Four patients had right amygdala enlargement (isolated amygdala enlargement in three patients; amygdala enlargement in addition to hippocampal sclerosis in one patient), and one patient with compression of an internal carotid-posterior communicating artery aneurysm to right amygdala on brain MRI. Interictal epileptiform or ictal discharges on EEG were found in the right temporal region in five patients. In all four patients with amygdala enlargement, amygdala enlargement was ipsilateral to EEG anomalies. In all patients, nasal pain was accompanied by ictal semiological features, such as autonomic, olfactory, abdominal, or psychic auras, and focal impaired awareness seizures, which are typically associated with mesial temporal lobe epilepsy. Conclusions Our findings suggest that nasal pain can occur as an epileptic aura in patients with temporal lobe epilepsy with probable involvement of the amygdala.

Micro-architectures, such as cellular truss structures, enhance the mechanical properties of structural materials while ensuring that they are lightweight in nature. Among others, stretching-dominated truss structures are known for their high modulus and yield strength, which makes them the best choice for lightweight structural applications. Finite element analysis of octahedral vs. octet structures is used to compare the differences in stress distribution in the stretching-dominated deformation of such trusses. Both octahedral and octet stretching-dominated structures were fabricated by fused deposition modeling (FDM)-based three-dimensional (3D) printing. These micro-architectures are printed with different polymeric materials, such as polylactic acid or polylactide (PLA), nylon 618, and a carbon fiber reinforced composite of PLA (CFRPLA). In addition, the CFRPLA filament with randomly suspended carbon fibers in PLA undergoes shear-induced alignment along the strut direction of the 3D printed micro-trusses, which leads to an improved Young's modulus as compared to the other materials. The properties of the 3D printed stretching-dominated micro-trusses are evaluated by compression testing, finite element analysis (FEA), and thermal analysis. The 3D printed octet structure of CFRPLA with fiber alignment exhibits the highest modulus and yield strength of 0.6 GPa and 17 MPa, respectively. Keywords: Architected material, Micro-truss, 3D printing, Stretching-dominated structures, Compressive stress and strain

Controlling the neutral plane of a multilayer structure is crucial in designing a reliable flexible display, where the bending strain imposed on the individual layers that are positioned closer to the neutral plane can be significantly reduced. In this study, we explore the usage of polymer/graphene composites with different concentrations of graphene flakes to systematically vary the modulus in attempt to control the location of the neutral plane to the desirable position. Nanoindentation of the PMMA/graphene composite film on Si substrate revealed that increasing the graphene flake content led to the enhancement in hardness and modulus of the composite. The increased Young's modulus caused a shift in the neutral plane position towards the organic emissive layers by ∼2.2 μm that resulted in a reduction of bending strain in the organic light emitting diodes with a typical multilayer structure. Furthermore, gas permeability against O2 and water molecules showed that the gas transmission rate of PMMA/graphene composites decreased as the content of graphene flakes increased since the randomly mixed graphene in PMMA can efficiently hinder the O2 and water molecules from transporting through the thickness of the composite, thereby enhancing the barrier properties.

A strategy for improving the stability of nickel-based solid oxide fuel cell (SOFC) anodes via compositional and microstructural engineering is presented. Ni content was reduced to 2 vol%, and nanosized Ni particles were uniformly dispersed in a mixed ionic-electronic conducting matrix comprising gadolinium-doped ceria (GDC) using a thin-film technique. Remarkable stability with no performance deterioration even after 100 reduction-oxidation cycles could be observed for the optimized nanostructured anodes. Cell performance at 500°C was enhanced, exceeding 650 mW/cm2. This study offers valuable insights for enhancing the durability, performance, and productivity of SOFCs.

The impact of a nanostructured Ni–yttria-stabilized zirconia (Ni–YSZ) anode on low-temperature solid oxide fuel cell (LT-SOFC) performance is investigated. By modifying processing techniques for the anode support, anode-supported SOFCs based on thin-film (∼1 μm) electrolytes (TF-SOFCs) with and without the nanostructured Ni–YSZ (grain size ∼100 nm) anode are fabricated and a direct comparison of the TF-SOFCs to reveal the role of the nanostructured anode at low temperature is made. The cell performance of the nanostructured Ni–YSZ anode significantly increases as compared to that of the cell without it, especially at low temperatures (500 °C). The electrochemical analyses confirm that increasing the triple-phase boundary (TPB) density near the electrolyte and anode interface by the particle-size reduction of the anode increases the number of sites available for charge transfer. Thus, the nanostructured anode not only secures the structural integrity of the thin-film components over it, it is also essential for lowering the operating temperature of the TF-SOFC. Although it is widely considered that the cathode is the main factor that determines the performance of LT-SOFCs, this study directly proves that anode performance also significantly affects the low-temperature performance.

In-situ transmission electron microscopy (TEM) annealing of submicron Al pillars (∼300–450 nm in diameter) fabricated by focused ion beam (FIB) shows that the dislocation loops formed by the high energy Ga+ ion beam impact near the material surface can be removed by annealing at around half of the melting point (Tm). Quantitative analysis of real-time TEM data reveals that the dislocation loops first show a ripening behavior at around 0.4Tm, i.e. larger loops coarsen at the expense of smaller ones. Subsequently, the ripened loops start to shrink and are eventually annihilated at ∼0.5Tm by the diffusion of thermally activated vacancies. Microcompression tests on the as-fabricated and annealed pillars suggest that the FIB-induced defects, particularly dislocation loops, distinctively affect the deformation behavior of submicron Al pillars; while the yield and flow stresses appear unaffected by the annealing, strain bursts are larger and more frequent in the annealed pillars compared to those of as-fabricated samples. In-situ TEM compression revealed that the initial plastic deformation and subsequent plastic flow of Al pillars are significantly altered by the presence of FIB-induced dislocation loops, as they actively respond to the applied stress. We observe that the initial dislocation activity in most FIB-prepared pillars was the glide of FIB-induced dislocation loops. With further straining, the dislocation loops escaped the pillar, leaving slip steps at the pillar surface and/or dislocation debris within the pillar volume via the interaction with other mobile dislocations. The subsequent dislocation slip is mostly localized at these locations, thereby forming large slip steps. Contrarily, in the case of annealed pillars, the deformation was rather homogeneous with the formation of multiple fine slip steps. The present direct TEM observations contribute to the understanding of the nature of FIB-induced defects and reveal their distinct roles in the deformation behaviors of submicron pillars.

Graphene is known to prevent permeation of gases that can effectively prevent oxidation of Ag nanowires. In this study, the role of the reduced graphene oxide (RGO) in chemical stability and its effect on the mechanical reliability was studied for a Ag nanowire/RGO hybrid transparent electrode. Bending fatigue tests up to 800 000 cycles were performed by monitoring the in situ resistance change while imposing fixed, uniform bending strain on Ag nanowire networks with and without a RGO layer. A thin layer of RGO with an optimized thickness of ∼0.8 nm deposited on the Ag nanowire networks sustained excellent reliability of the Ag nanowire networks, where the fractional resistance increase was 2.7% after 800 000 cycles. Furthermore, adopting the RGO layer significantly lowered the oxidation of Ag nanowires, and the bending fatigue properties after exposure to ambient air for 132 h at 70 °C indicated remarkable enhancement due to suppression of the oxide formation on the surface of the Ag nanowires. Lastly, a highly reliable Ag nanowire/RGO hybrid electrode was fabricated using mechanical welding by subjecting it to bending strain in order to form localized junctions without having to go through any post annealing processes.

High-quality Pt thin films are prepared by atomic layer deposition (ALD) using metal-organic precursors dimethyl-(N,N-dimethyl-3-butene-1-amine-N) platinum (C8H19NPt) and with diluted molecular oxygen (O2) as a reactant. The films are grown at a relatively low temperature of 225 °C on a thermally grown SiO2 substrate, and the process shows all the necessary qualities of an ideal ALD such as self-limiting growth characteristics and a well-defined ALD temperature window between 200 and 250 °C. Noticeably, the current ALD-Pt process shows a very high growth per cycle of 0.167 nm without an incubation period at 225 °C, and perfect conformality is obtained at a dual trench structure (top and bottom width: 40 and 15 nm) with an aspect ratio of around 6.3. The resistivity of the ALD-Pt film at ∼39 nm in thickness deposited at 225 °C is almost the same (∼10.8 μΩ cm) as its bulk resistivity (10.6 μΩ cm), and it is as low as ∼12 μΩ cm at 25 nm in thickness. Comprehensive analyses using x-ray photoelectron spectrosc...

Defect-free AuAg alloy nanowires have the potential to be used in various plasmonic devices due to their superior chemical stability and broad applicable range of wavelengths. Alloyed nanowires have different stacking fault energies that can result in different deformation behavior compared to single element nanowires; however, an in-depth analysis of such material system is yet to be explored. In this study, defect-free single crystalline Au30Ag70 alloy nanowires are synthesized by topotaxial growth method and tested in tension using an in-situ pico-indenter. Deformation twinning that results in superplastic deformation of alloy nanowires is experimentally observed. The critical dimension of Au30Ag70 alloy nanowires at which transition from ordinary plasticity to deformation twinning occurs, is experimentally determined to be similar to 333 nm, which is about 2 time larger than that of Au nanowires. Stacking fault energy, which is the key element determining the deformation mode, of Au30Ag70 alloy nanowires is 21 mJ/m(2), which is smaller than that of Au nanowire with stacking fault energy of 31 mJ/m(2). The decrease in the stacking fault energy in the case of the alloy nanowires resulted in stabilization of deformation twinning to a larger critical dimension before transitioning to ordinary plasticity. (C) 2019 Published by Elsevier B.V.

Several metabolomics of polymeric flavan-3-ols have reported that proanthocyanidins are extensively metabolized by gut microbiota. 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone (DHPV) has been reported to be the major microbial metabolite of proanthocyanidins. We demonstrated that DHPV has stronger prevention effect on tumor necrosis factor (TNF)-α-stimulated adhesion of THP-1 human monocytic cells to human umbilical vein endothelial cells compared to its potential precursors such as procyanidin A1, A2, B1 and B2, (+)catechin, (−)epicatechin and its microbial metabolites such as 3-(3,4-dihydroxyphenyl)propionic acid and 2-(3,4-dihydroxyphenyl)acetic acid. Mechanism study showed that DHPV prevents THP-1 monocyte-endothelial cell adhesion by downregulating TNF-α-stimulated expressions of the two biomarkers of atherosclerosis such as vascular cell adhesion molecule-1 and monocyte chemotactic protein-1, activation of nuclear factor kappa B transcription and phosphorylation of I kappa-B kinase and IκBα. We suggested that DHPV has higher potentiality in prevention of atherosclerosis among the proanthocyanidin metabolites.

Binderless, additive-less Si electrode design is developed where a nanoporous ZnO matrix is coated on a Si microparticle electrode to accommodate extreme Si volume expansion and facilitate stable electrochemical cycling. The conversion reaction of nanoporous ZnO forms an ionically and electrically conductive matrix of metallic Zn embedded in Li2O that surrounds the Si microparticles. Upon lithiation, the porous Li2O/Zn matrix expands with Si preventing extensive pulverization while Zn serves as active material to form LixZn to further enhance capacity. Electrodes with Si mass loading of 1.5 mg/cm2 was fabricated and high initial capacity of ~3,900 mAh/g was achieved with excellent reversible capacity of ~1,500 mAh/g (areal capacity ~1.7 mAh/cm2) beyond 200 cycles. A high first cycle coulombic efficiency was obtained owing to the conversion reaction of nanoporous ZnO, which is a notable feature in comparison to conventional Si anodes. Ex situ analyses confirmed that the nanoporous ZnO coating maintained the coalescence of SiMPs throughout extended cycling. Therefore, the Li2O/Zn matrix derived from conversion reacted nanoporous ZnO acted as an effective buffer to lithiation induced stresses from volume expansion and served as a binder-like matrix that contribute to the overall electrode capacity and stability.

Recently developed textile and paper based supercapacitors are well-suited for wearable energy storage devices due to their mechanical flexibility and stretchability. In this study, the effects of mechanical straining on carbon nanotube coated textiles are studied, and we demonstrate the pre-straining of the textile can result in an enhanced specific capacitance as well as power and energy densities. In-situ resistance measurement during mechanical straining of the textile capacitors show a decrease in resistance with tensile straining, which contributed directly to the enhancement of electrochemical performance. Two different carbon nanotube textiles based on polyester and cotton with different mechanical behaviors are examined, where the polyester textile show an increase in specific capacitance from 53.6 F g � 1 to 85.7 F g � 1 after the textile is pre-strained to 30% permanent elongation prior to electrochemical testing, constituting a 37% enhancement. Similarly, the cotton textile shows an enhancement in specific capacitance from 122.1 F g � 1 to 142.0 F g � 1 after 30% permanent elongation, which is a 22% enhancement. Specific capacitance, energy density, and power density are increased further by electroplating of MnO2 nanoparticles on the carbon nanotube coated cotton textile and then imposing a permanent elongation of 30%. Our results indicate that the simple mechanical pre-straining of the textile fibers contribute to significant enhancements in the electrochemical performance of the supercapacitors.

External stresses are applied during operation or storage in flexible electronics, which makes understanding time-dependent plastic deformation of nanobuilding blocks more crucial for ensuring the reliability of the devices. Here, we systematically explored the time-dependent nanoscale plasticity of single-crystal ZnO nanorods and its size effects. A series of compression creep tests under different low stresses (in elastic regime) were performed on vertically oriented rods having equivalent diameters in the range of ∼200 to ∼2000 nm. It was revealed that creep indeed occurs in the rods even at ambient temperature, and is more pronounced in smaller nanorods. Analyzing the stress exponent and the activation volume suggests that the enhanced plasticity may be controlled by the diffusion creep (through the “space-charge layer” near the surface and/or along the interface between the punch and the top surface of the rod), which is supported by the results from in situ creep tests under electron-beam irradiation and in situ electric measurements.

Early gastric cancer (EGC) is defined as a carcinoma in which invasion is limited to the mucosa and submucosa, regardless of lymph node status and distant metastasis. Recent advances in multidetector computed tomography (CT) with multiplanar reformation (MPR) provide a powerful tool for identifying gastric wall invasion and the perigastric extent of gastric cancer. In addition, MPR images confer advantages in the assessment of both intra- and extraluminal processes of the gastric wall and the evaluation of more distant regions, such as the paraaortic lymph nodes and other abdominal organs. Virtual endoscopy performed after air distention of the stomach can aid in the evaluation of gastric endoluminal morphologic features and the extent of EGC. Moreover, virtual endoscopy helps in detecting subtle mucosal changes and differentiating them from submucosal lesions in the same way as conventional endoscopy. Virtual endoscopy can depict abnormal endoluminal lesions within a wider field of view than can conventional endoscopy, and there are no "blind spots" because retrospective image reformation is available, which provides useful information for preoperative mapping. Multidetector CT with MPR and virtual endoscopy is a powerful, noninvasive tool for the early detection and accurate preoperative staging of EGC.

Recently there is strong interest in lightweight, flexible, and wearable electronics to meet the technological demands of modern society. Integrated energy storage devices of this type are a key area that is still significantly underdeveloped. Here, we describe wearable power devices using everyday textiles as the platform. With an extremely simple "dipping and drying" process using single-walled carbon nanotube (SWNT) ink, we produced highly conductive textiles with conductivity of 125 S cm(-1) and sheet resistance less than 1 Omega/sq. Such conductive textiles show outstanding flexibility and stretchability and demonstrate strong adhesion between the SWNTs and the textiles of interest. Supercapacitors made from these conductive textiles show high areal capacitance, up to 0.48F/cm(2), and high specific energy. We demonstrate the loading of pseudocapacitor materials into these conductive textiles that leads to a 24-fold increase of the areal capacitance of the device. These highly conductive textiles can provide new design opportunities for wearable electronics and energy storage applications.

Multilayer thin films with bilayer thicknesses in the nanometer range have been reported to have very high strengths. A previous study has shown that Al–Al3Sc multilayers, with bilayer thicknesses as small as 6 nm, have hardnesses as high as � 3 GPa as measured by sharp tip nanoindentation. In the present study, we have avoided some of the complications associated with sharp tip nanoindentation by directly measuring the yield strengths and strain hardening/softening properties of Al–Al3Sc multilayers using microcompression testing methods with a nanoindenter. The results show the expected trend of increasing yield strength with decreasing bilayer thickness, and compare favorably with estimates of the yield strengths based on sharp tip nanoindentation. During deformation, the Al–Al3Sc multilayer pillars with smaller bilayer spacings experience considerable strain softening, resulting in a ‘‘flat-top mushroom” shape after deformation. We have developed a numerical model to account for this inhomogeneous deformation behavior and to calculate stress–strain relationships during strain softening. A new transmission electron microscopy study of a deformed pillar shows that the softening is a result of destruction of the layered structure due to shearing and rotation. 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The size-dependent strength of face-centered cubic (fcc) metals, as revealed by uniaxial compression of nanopillars, suggests that plasticity is dislocation source-controlled, with fewer sources in smaller pillars producing a “smaller is stronger” effect. To further investigate this phenomenon we have studied the effects of prestraining and annealing on the deformation properties of [0 0 1] Au nanopillars. By making pillars from an epitaxial film of [0 0 1] Au on [0 0 1] MgO, using focused ion beam machining, we are able to create both puck-shaped pillars that can be stably prestrained and pillars with a high aspect ratio, which can be tested in uniaxial compression. We find that prestraining dramatically reduces the flow strength of nanopillars while annealing restores the strength to the pristine levels. These unusual effects are not seen in bulk fcc metals, which behave in the opposite way. We discuss their possible causes in terms of dislocation densities using transmission electron microscopy.

Deoxidation of β-titanium was investigated by Ca-CaCl 2 and Ca-CaF 2 fluxes at 900 to 1400°C. The content of oxygen in Ti was strongly dependent not only on the Ca potential but on the stability of CaO in the fluxes. The present experimental results indicate that deoxidation of Ti by Ca-calcium halide fluxes could be controlled by the activity ratio of CaO to Ca. The ratio of a CaO/ a Ca =0.06~0.1 was strongly recommended for obtaining oxygen content of 40~160 ppm.

The kinetic study of the nitrogen dissolution into the molten steel was investigated by an isotope exchange technique. The effects of O, S, C, B, and Mn addition on surface reaction have been considered at 1873 K. Experimental results show that the rate determining step of nitrogen dissolution into molten Fe–O–S alloys would be dissociation reaction and the rate constant on bare surface of the liquid steel (k0) is 3.84×10−5 (mol/cm2·s·atm). The adsorption coefficients for oxygen, sulfur, and boron which were applied the dissociation determining model were calculated to be KO=120, KS=65, and KB=0.9, respectively. In case of manganese addition, the rate constant can be increased with increasing the content of manganese. It seems that rate constant of bare surface of Fe–Mn alloy should be affected by addition of manganese.

PVDF and P(VDF-TrFE) nano- and micro- structures have been widely used due to their potential applications in several fields, including sensors, actuators, vital sign transducers and energy harvesters. In this study, we developed vertically aligned P(VDF-TrFE) core-shell structures using high modulus polyurethane acrylate (PUA) pillars as the support structure to maintain the structural integrity. In addition, we were able to improve the piezoelectric effect by 1.85 times from 40 ± 2 to 74 ± 2 pm/V when compared to the thin film counterpart, which contributes to the more efficient current generation under a given stress, by making an effective use of the P(VDF-TrFE) thin top layer as well as the side walls. We attribute the enhancement of piezoelectric effects to the contributions from the shell component and the strain confinement effect, which was supported by our modeling results. We envision that these organic-based P(VDF-TrFE) core-shell structures will be used widely as 3D sensors and power generators because they are optimized for current generations by utilizing all surface areas, including the side walls of core-shell structures.

Nanoscale time-dependent mechanical-electrical coupled behavior of single crystal ZnO nanorods was systematically explored, which is essential for accessing the long-term reliability of the ZnO nanorod-based flexible devices. A series of compression creep tests combined with in-situ electrical measurement was performed on vertically-grown single crystal ZnO nanorods. Continuous measurement of the current (I)-voltage (V) curves before, during, after the creep tests revealed that I is non-negligibly increased as a result of the time-dependent deformation. Analysis of the I-V curves based on the thermionic emission-diffusion theory allowed extraction of nanorod resistance, which was shown to decrease as time-dependent deformation. Finally, based on the observations in this study, a simple analytical model for predicting the reduction in nanorod resistance as a function of creep strain that is induced from diffusional mechanisms is proposed and this model was demonstrated to be in an excellent agreement with the experimental results.

Nanoindentation has developed as a practical tool for determining the mechanical properties of thin films. In this paper, we develop a method for determining the hardness of thin films on substrates based on measurements of the contact stiffness vs. depth of indentation and prior knowledge of the elastic properties of the film and substrate. The method utilizes an analysis of contact stiffness vs. contact area for purely elastic indentation to correct for the effects of surface roughness and pile-up/sink-in on the contact area during elastic–plastic indentation of elastically mismatched film/substrate systems. We find the hardness to be essentially depth independent for indentation depths approaching the thickness of the film for several thin film/substrate systems. This new technique is described in detail and is applied to the nanoindentation of compliant films on stiff substrates (Al/Si and Al/sapphire) and stiff films on compliant substrates (W/Si and W/glass).

In this paper, we describe an on-going effort to develop a thin film combinatorial method for identifying alloy compositions of potential interest as structural materials. To investigate this idea, compositionally graded Ti–Al thin films have been sputter deposited onto Si substrates, and the mechanical properties of the “library” of compositions are then probed using nanoindentation. This combinatorial method offers the possibility of rapidly varying the compositions and microstructures of alloys and quickly determining the compositions and microstructures of greatest interest for further development as bulk structural alloys. Nanoindentation experiments are used to extract the properties of the film so that the bulk properties of the material may be estimated. A new method for extracting the hardness of films on substrates from nanoindentation experiments has been developed and is applied to the compositionally graded Ti–Al thin films. Together with the nanoindentation data and a compositional analysis, we are able to establish a relationship between the hardness of the film and the composition. We discuss the results of these combinatorial experiments in connection with estimating the properties of bulk materials.

The uniaxial tensile properties of a B2 Fe–40Al based alloy containing 0.7 at.% carbon and 0.5 at.% boron have been obtained at room and elevated temperatures in air as a function of strain rate and compared to the response of a similar alloy without boron (i.e Fe–40Al–0.6C). Furthermore, tests were also conducted as a function of strain rate in oxygen at room temperature to elucidate the effect of environment on these properties. Both alloys contain a dispersion of a perovskite carbide within the grains and at grain boundaries. In addition, the quaternary alloy contains a fine dispersion of metastable borides and complex faults within the grains. Yield stress and tensile elongation appear strain rate insensitive (in the regime tested) for the boron-containing alloy at room temperature in oxygen, whereas some loss in elongation is encountered at the slowest rate in the ternary alloy; in all cases, fracture path is intergranular. In air, at room temperature, a strong strain-rate dependence of elongation is recognized in both alloys, their response being identical at the faster rates but diverging at the slow rates. A strong correlation is noted between the increase in percent transgranular cleavage and the drop in tensile elongation. The brittle-to-ductile transition temperature is sensitive to strain rate, shifting to higher temperatures rapidly with increasing strain rate. A variety of fracture paths is encountered depending on test temperature and strain rate.

Developing a commercially viable silicon anode as a replacement for graphite has been the topic of intense research and discussion. Numerous attempts have been made including the use of nanoscale structures smaller than silicon’s critical fracture size (e.g. nanoparticles, nanowires, nanotubes, etc.). However, nanoscale structures, while sufficiently effective in lab scale, are difficult and expensive to scale up. To address this issue, applying a thin coat of polymer with self-healing chemistries has been reported as an effective remedy to enhance the cycle life of the silicon microparticle anode. The self-healing chemistry enabled mechanical fractures generated during the cycling process to self-heal. As a result, excellent cycle life was obtained compared to conventional microscale anodes. However, there still is room to improve the mechanical and electrochemical performances of the anode, most notably areal capacity and flexibility, while using large scale processes. In this study, a free standing silicon microparticle and self-healing polymer (SiSHP) composite is fabricated demonstrating long cycle life while still retaining high capacity (up to ~2,800mAhg-1 and ~3.5mAhcm-2) without a metal foil current collector. SiSHP composite is prepared by simple, inexpensive, and scalable approach. The SiSHP composite consists of silicon microparticles embedded within a self-healing polymeric matrix providing sufficient space for volume expansion during lithiation. The self-healing chemistry reduces irreversible loss of electric contact due to mechanical degradation prevalent in conventional slurry cast silicon electrode design. In addition, because the SiSHP composite eliminates the need for a metal current collector, adhesion issues between the electrode and current collector that arise with repeated bending are eliminated, thereby ensuring minimal loss in mechanical and electrochemical properties even after undergoing repeated bending. We found that a 1:1 Si/SHP weight ratio with 10 wt. % carbon conductive additive exhibits the optimal balance between high capacity and providing sufficient polymer matrix for stable cycling behavior. The fabricated SiSHP composite is moldable into the required shape and dimension ranging from millimeter to tens of centimeter-scale. The freestanding feature of the SiSHP composite anode eliminates the need for a metal foil current collector thereby reducing the non-active mass, which is beneficial to enhancing capacity and energy density of Lithium-ion cells.

Graphene is a single-atomic-layer material with excellent mechanical properties and has the potential to enhance the strength of composites. Its two-dimensional geometry, high intrinsic strength and modulus can effectively constrain dislocation motion, resulting in the significant strengthening of metals. Here we demonstrate a new material design in the form of a nanolayered composite consisting of alternating layers of metal (copper or nickel) and monolayer graphene that has ultra-high strengths of 1.5 and 4.0 GPa for copper-graphene with 70-nm repeat layer spacing and nickel-graphene with 100-nm repeat layer spacing, respectively. The ultra-high strengths of these metal-graphene nanolayered structures indicate the effectiveness of graphene in blocking dislocation propagation across the metal-graphene interface. Ex situ and in situ transmission electron microscopy compression tests and molecular dynamics simulations confirm a build-up of dislocations at the graphene interface.

There have been intensive research activities to lower the operating temperature of solid oxide fuel cells (SOFC) to avoid problems related to the high-temperature (≥ 800 oC) operation, such as reliability and cost issues, and to expand the application fields toward portable and mobile power sources. In this regard, thin-film electrolytes and nanostructure electrodes have been at the center of interests to reduce the ohmic and polarization losses while decreasing the operating temperatures. The effect of thinning down the electrolyte is straightforward, however, that of particle size reduction at the electrode is rather complicated. One of the main reasons is the difficulty of elucidating various electrode reaction mechanisms. Another reason can be the difficulty of fabricating the nanostructure electrodes. If conventional powder processing is used, it is challenging to reduce the electrode particle size due to the original particle size of the starting powder and high-temperature sintering. On the other hand, in common thin-film-based SOFCs, nanostructure noble metal electrodes, such as Pt, are employed, thus it is difficult to interrogate the effect of the particle size reduction of the widely used SOFC electrodes. Owing to the research efforts during the last decade, we have been able to obtain high-performance low-temperature-operating SOFCs (LT-SOFCs) based on the anode-supported platform by implementing thin-film electrolytes and nanostructure electrodes, while using the common SOFC materials. A peak power density as high as 600 mW cm-2 at 500 oC was achieved based on the nanostructure Ni-YSZ anode, ~1 micron-thick YSZ-GDC bilayer electrolyte, and nanostructure LSC or LSC-GDC composite cathode. The active cell components are fabricated by using pulsed laser deposition (PLD) and the particle size of the anode is 100-200 nm, that of the cathode is around 10-several 10s nm. Since the most interested topic regarding the LT-SOFCs has been the cell power output, the study on the effect of nanostructure electrodes at LT is rather not intensively performed. Therefore, in the current presentation, we will exhaustively review and discuss the impact and influence of the particle size reduction to nanoscale at both the cathode and the anode on LT-SOFCs. The distinctive characteristics of the nanoscale electrodes will be presented based on the half-cell and full-cell tests, and the direct comparisons between the cells in which the only difference is the electrode particle size. Acknowledgement The authors are grateful to the Global Frontier R&D Program on Center for Multiscale Energy Systems (Grant No. NRF-2015M3A6A7065442) of the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT & Future Planning (MSIP), and to the Institutional Program (2E26081) of Korea Institute of Science and Technology (KIST) for financial support. References J.-H. Park, W.-S. Hong, G. C. Kim, H. J. Chang, J.-H. Lee, K. J. Yoon, and J.-W. Son, J. Electrochem. Soc, 160, F1027 (2013) H.-S. Noh, K. J. Yoon, B.-K. Kim, H.-J. Je, H.-W. Lee, J.-H. Lee, and J.-W. Son, J. Power Sources, 247, 105 (2014) J.-H. Park, W.-S. Hong, K. J. Yoon, J.-H. Lee, H.-W. Lee, and J.-W. Son, J. Electrochem. Soc., 161, F16 (2014) J. H. Park, S. M. Han, K. J. Yoon, H. Kim, J. Hong, B.-K. Kim, J.-H. Lee, and J.-W. Son, J. Power Sources, 315, 324 (2016)

Lithium-ion battery cathode material has been the subject of much research in both academia and industry in order to improve its electrochemical properties and cyclability. A prime candidate for replacing the relatively expensive and unstable LiCoO2, is the Lil[NiCoMn]O2 cathode material. Being a ternary material, the Li[NiCoMn]O2 has ample room for composition optimization. As such, extended investigations have been conducted to optimize the electrochemical properties of Li[NiCoMn]O2. However, there arose a need for the evaluation of the mechanical properties of Li[NiCoMn]O2 in order to remedy the deterioration of cathode cycle life due to stress development during repeated charge/discharge cycles. In this study, an efficient and high throughput combinatorial methodology is developed using sputter deposition technique and applied to the characterization of mechanical properties degradation of Li[NiCoMn]O2 as a result of repeated charge/discharge cycling. Co-sputter deposition of LiCoO2, LiNiO2, and LiMn2O4 compound targets was carried out in order to create the necessary concentration gradient to efficiently fabricate a Li[NiCoMn]O2 composition library. EDS analysis confirmed that the fabricated composition library encompassed a broad composition range of 20~80 at. % Ni content, 3~44 at. % Co content, and 5~50 at. % Mn content. XRD analysis confirmed a layered α -NaFeO2 (R3-m) structure for all compositions. Mechanical properties characterization by nanoindentation was carried out pre and post five charge/discharge cycles conducted via voltammetry sweep cycles between 2.5V and 4.5V at a scan rate of 1mV/s. Elastic modulus and hardness values pre and post charge/discharge cycles were found to both exhibit a strong composition dependency; Ni-rich compositions exhibited highest hardness values of 12GPa and Mn-rich compositions exhibited highest modulus values of 170GPa pre charge/discharge cycling. However, post charge/discharge cycling nanoindentation results indicated that Mn-rich compositions were characterized to have highest retention of its mechanical properties whereas the properties degraded more significantly for Ni-rich and Co-rich compositions. Electrochemical performance was analyzed at Ni-rich Li[Ni0.80Co0.10Mn0.10]O2, Co-rich Li[Ni0.40Co0.50Mn0.10]O2, and Mn-rich Li[Ni0.60Co0.03Mn0.37]O2, Li[Ni0.45Co0.10Mn0.45]O2­, and Li[Ni0.33Co0.30Mn0.37]O2 compositions. Overall, a strong correlation for enhanced mechanical properties retention leading to superior discharge capacity retention was found with high Mn compositions demonstrating both superior mechanical properties retention and discharge capacity retention. Li[Ni0.33Co0.30Mn0.37]O2 composition, which retained 50% and 38% of its hardness and elastic modulus after cycling, demonstrated 90.61% discharge capacity retention after 20 cycles at 1C rate. Our results, obtained via the developed high throughput and efficient combinatorial analysis, indicate that the manganese rich compositions, which were characterized to have superior mechanical properties, demonstrate the best discharge capacity retention capability even after multiple charge/discharge cycles.

One of the top design priorities for semiconductor chemical sensors is developing simple, low-cost, sensitive and reliable sensors to be built in handheld devices. However, the need to implement heating elements in sensor devices, and the resulting high power consumption, remains a major obstacle for the realization of miniaturized and integrated chemoresistive thin film sensors based on metal oxides. Here we demonstrate structurally simple but extremely efficient all oxide chemoresistive sensors with ~90% transmittance at visible wavelengths. Highly effective self-activation in anisotropically self-assembled nanocolumnar tungsten oxide thin films on glass substrate with indium-tin oxide electrodes enables ultrahigh response to nitrogen dioxide and volatile organic compounds with detection limits down to parts per trillion levels and power consumption less than 0.2 microwatts. Beyond the sensing performance, high transparency at visible wavelengths creates opportunities for their use in transparent electronic circuitry and optoelectronic devices with avenues for further functional convergence., Korea (South). Ministry of Intelligence and Economy (Contract K0004114), Korea Institute of Science and Technology (Grant 2E22121), Korea (South). Ministry of Environment (Research Program)

c SK Hynix, 2091 Gyeongchung-daero, Bubal-eub, Icheon-si, Gyeonggi-do, 467-701, Republic of Korea Abstract. Characterization of silicon stress near copper (Cu)-filled through-silicon via(s) (TSVs) was demon- strated using high-resolution micro-Raman spectroscopy. For depth profiling of Si stress distribution near TSVs, a polychromator-based, multiwavelength excitation Raman measurement with different probing depths was used. The design concept of the polychromator-based, multiwavelength micro-Raman spectroscopy system, including the importance of the high-spectral resolution and multiwavelength excitation capability in three-dimen- sional (3-D) Si stress characterization, was described. Silicon stress near Cu-filled TSVs, with various sizes and layouts, was measured and analyzed before and after Cu annealing steps. Main factors impacting Si stress near Cu-filled TSVs are analyzed based on Raman characterization results on various types of TSV structures, lay- outs, and Cu annealing conditions. Large variations in Si stress in TSV arrays were measured in wafers with poor Cu fill characteristics and in wafers annealed in nonoptimized conditions. The Cu annealing sequence and annealing conditions are found to be significantly important for managing Si stress and the reliability of Cu-filled TSVs. Substantially lower Si stress was measured near Cu-filled TSVs with voids. Multiwavelength micro- Raman spectroscopy can be used as a very effective noncontact, nondestructive, inline TSV process and Si stress monitoring technique. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1 .JMM.13.1.011205)

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