Intercritically Annealed Medium-Manganese Steel: Insights into Microstructural and Microtextural Evolution, Strain Distribution, and Grain Boundary Characteristics.

Aluminum-incorporated medium-manganese steel (MMnS) has potential for lightweight transport applications owing to its impressive mechanical properties. Increasing the austenite volume fraction and making microstructural changes are key to manufacturing MMnS. However, the grain boundary character and strain distribution of intercritically annealed low-density MMnS have not been extensively scrutinized, and the effects of crystallographic texture orientation on tensile properties remain ambiguous. Therefore, in this study, the microstructure, microtexture, strain distribution, and grain boundary characteristics of a hot-rolled medium-Mn steel (Fe-0.2 C-4.3 Al-9.4 Mn (wt%)) were investigated after intercritical annealing (IA) at 750, 800, or 850 °C for 1 h. The results show that the 800 °C annealed sample exhibited the highest austenite volume fraction among the specimens (60%). The duplex microstructure comprised lath-type γ-austenite, fine α-ferrite, and coarse δ-ferrite. As the IA temperature increased, the body-centered cubic phase orientation shifted from <001> to <111>. At higher temperatures, the face-centered cubic phase was oriented in directions ranging from <101> to <111>, and the sums of the fractions of high-angle grain boundaries and coincidence-site-lattice special boundaries were significantly increased. The 800 °C annealed sample with a high austenite content and strong γ-fiber {111}//RD orientation demonstrated a noteworthy tensile strength (1095 MPa) and tensile elongation (30%).

Effects of the Mg Content on Microstructural and Corrosion Characteristics of Hot-Dip Al-Si-Mg Alloy-Coated Steel Sheets.

Hot-dip Al-Si alloy coatings with excellent resistance to corrosion and high-temperature oxidation have emerged as promising lightweight substitutes for conventional corrosion-resistant coatings. The introduction of Mg can be an effective strategy for enhancing the sacrificial protection capability of Al-Si coatings. In this study, the effects of Mg addition on the morphology, electrochemical behavior, and mechanical properties of Al-Si coatings were investigated, along with the Mg-content optimization of the coating layer. Adding Mg promoted the formation of finely distributed eutectic intermetallic phases, such as Al/Mg2Si and the primary Mg2Si phase. Notably, the Mg2Si phase coarsened significantly when ≥15 wt.% of Mg was added. In addition, an Al3Mg2 intermetallic compound was observed in coating layers containing >20 wt.% of Mg, reducing the adhesion of the coating layers. Samples containing 5-10 wt.% of Mg exhibited excellent corrosion resistance (owing to a uniform distribution of the fine eutectic Al/Mg2Si phase and the formation of stable corrosion products), whereas those containing 20 wt.% of Mg exhibited unremarkable corrosion resistance (owing to the formation of an Al3Mg2 phase that is susceptible to intergranular corrosion).

Enhanced Long-Term Reliability of Seal DeltaSpot Welded Dissimilar Joint between 6061 Aluminum Alloy and Galvannealed Steel via Excimer Laser Irradiation.

Structural-adhesive-assisted DeltaSpot welding was used to improve the weldability and mechanical properties of dissimilar joints between 6061 aluminum alloy and galvannealed HSLA steel. Evaluation of the spot-weld-bonded surfaces from lap shear tests after long-term exposure to chloride and a humid atmosphere (5% NaCl, 35 °C) indicated that the long-term mechanical reliability of the dissimilar weld in a corrosive environment depends strongly on the adhesive-Al6061 alloy bond strength. Corrosive electrolyte infiltrated the epoxy-based adhesive/Al alloy interface, disrupting the chemical interactions and decreasing the adhesion via anodic undercutting of the Al alloy. Due to localized electrochemical galvanic reactions, the surrounding nugget matrix suffered accelerated anodic dissolution, resulting in an Al6061-T6 alloy plate with degraded adhesive strength and mechanical properties. KrF excimer laser irradiation of the Al alloy before adhesive bonding removed the weakly bonded native oxidic overlayers and altered the substrate topography. This afforded a low electrolyte permeability and prevented adhesive delamination, thereby enhancing the long-term stability of the chemical interactions between the adhesive and Al alloy substrate. The results demonstrate the application of excimer laser irradiation as a simple and environmentally friendly processing technology for robust adhesion and reliable bonding between 6061 aluminum alloy and galvannealed steel.

Three-Dimensional Imaging for Multiplex Phenotypic Analysis of Pancreatic Microtumors Grown on a Minipillar Array Chip.

Three-dimensional (3D) culture of tumor spheroids (TSs) within the extracellular matrix (ECM) represents a microtumor model that recapitulates human solid tumors in vivo, and is useful for 3D multiplex phenotypic analysis. However, the low efficiency of 3D culture and limited 3D visualization of microtumor specimens impose technical hurdles for the evaluation of TS-based phenotypic analysis. Here, we report a 3D microtumor culture-to-3D visualization system using a minipillar array chip combined with a tissue optical clearing (TOC) method for high-content phenotypic analysis of microtumors. To prove the utility of this method, phenotypic changes in TSs of human pancreatic cancer cells were determined by co-culture with cancer-associated fibroblasts and M2-type tumor-associated macrophages. Significant improvement was achieved in immunostaining and optical transmission in each TS as well as the entire microtumor specimen, enabling optimization in image-based analysis of the morphology, structural organization, and protein expression in cancer cells and the ECM. Changes in the invasive phenotype, including cellular morphology and expression of epithelial-mesenchymal transition-related proteins and drug-induced apoptosis under stromal cell co-culture were also successfully analyzed. Overall, our study demonstrates that a minipillar array chip combined with TOC offers a novel system for 3D culture-to-3D visualization of microtumors to facilitate high-content phenotypic analysis.

Effects of Intense Pulsed Light (IPL) Rapid Annealing and Back-Channel Passivation on Solution-Processed In-Ga-Zn-O Thin Film Transistors Array.

We report on the effects of the intense pulsed light (IPL) rapid annealing process and back-channel passivation on the solution-processed In-Ga-Zn-O (IGZO) thin film transistors (TFTs) array. To improve the electrical properties, stability and uniformity of IGZO TFTs, the oxide channel layers were treated by IPL at atmospheric ambient and passivated by photo-sensitive polyimide (PSPI). When we treated the IGZO channel layer by the IPL rapid annealing process, saturation field effect mobility and subthreshold swing (S.S.) were improved. And, to protect the back-channel of oxide channel layers from oxygen and water molecules, we passivated TFT devices with photo-sensitive polyimide. The IGZO TFTs on glass substrate treated by IPL rapid annealing without PSPI passivation showed the field effect mobility (µFE) of 1.54 cm2/Vs and subthreshold swing (S.S.) of 0.708 V/decade. The PSPI-passivated IGZO TFTs showed higher µFE of 2.17 cm2/Vs than that of device without passivation process and improved S.S. of 0.225 V/decade. By using a simple and fast intense pulsed light treatment with an appropriate back-channel passivation layer, we could improve the electrical characteristics and hysteresis of IGZO-TFTs. We also showed the improved uniformity of electrical characteristics for IGZO TFT devices in the area of 10 × 40 mm2. Since this IPL rapid annealing process could be performed at a low temperature, it can be applied to flexible electronics on plastic substrates in the near future.

Multiplex quantitative analysis of stroma-mediated cancer cell invasion, matrix remodeling, and drug response in a 3D co-culture model of pancreatic tumor spheroids and stellate cells.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a stroma-rich carcinoma, and pancreatic stellate cells (PSCs) are a major component of this dense stroma. PSCs play significant roles in metastatic progression and chemoresistance through cross-talk with cancer cells. Preclinical in vitro tumor model of invasive phenotype should incorporate three-dimensional (3D) culture of cancer cells and PSCs in extracellular matrix (ECM) for clinical relevance and predictability. METHODS: PANC-1 cells were cultured as tumor spheroids (TSs) using our previously developed minipillar chips, and co-cultured with PSCs, both embedded in collagen gels. Effects of PSC co-culture on ECM fiber network, invasive migration of cancer cells, and expression of epithelial-mesenchymal transition (EMT)-related proteins were examined. Conditioned media was also analyzed for secreted factors involved in cancer cell-PSC interactions. Inhibitory effect on cancer cell invasion was compared between gemcitabine and paclitaxel at an equitoxic concentration in PANC-1 TSs co-cultured with PSCs. RESULTS: Co-culture condition was optimized for the growth of TSs, activation of PSCs, and their interaction. Increase in cancer cell invasion via ECM remodeling, invadopodia formation and EMT, as well as drug resistance was recapitulated in the TS-PSC co-culture, and appeared to be mediated by cancer cell-PSC interaction via multiple secreted factors, including IL-6, IL-8, IGF-1, EGF, TIMP-1, uPA, PAI-1, and TSP-1. Compared to gemcitabine, paclitaxel showed a greater anti-invasive activity, which was attributed to suppresion of invadopodia formation in cancer cells as well as to PSC-specific cytotoxicity abrogating its paracrine signaling. CONCLUSIONS: Here, we established 3D co-culture of TSs of PANC-1 cells and PSCs using minipillar histochips as a novel tumoroid model of PDAC. Our results indicate usefulness of the present co-culture model and multiplex quantitative analysis method not only in studying the role of PSCs and their interactions with tumor cell towards metastatic progression, but also in the drug evaluation of stroma-targeting drugs.

Pitch-tunable pillar arrays for high-throughput culture and immunohistological analysis of tumor spheroids.

Tumor spheroids are multicellular, three-dimensional (3D) cell culture models closely mimicking the microenvironments of human tumors in vivo, thereby providing enhanced predictability, clinical relevancy of drug efficacy and the mechanism of action. Conventional confocal microscopic imaging remains inappropriate for immunohistological analysis due to current technical limits in immunostaining using antibodies and imaging cells grown in 3D multicellular contexts. Preparation of microsections of these spheroids represents a best alternative, yet their sub-millimeter size and fragility make it less practical for high-throughput screening. To address these problems, we developed a pitch-tunable 5 × 5 mini-pillar array chip for culturing and sectioning tumor spheroids in a high throughput manner. Tumor spheroids were 3D cultured in an alginate matrix using a twenty-five mini-pillar array which aligns to a 96-well. At least a few tens of spheroids per pillar were cultured and as many as 25 different treatment conditions per chip were evaluated, which indicated the high throughput manner of the 5 × 5 pillar array chip. The twenty-five mini-pillars were then rearranged to a transferring pitch so that spheroid-containing gel caps from all pillars can be embedded into a specimen block. Tissue array sections were then prepared and stained for immunohistological examination. The utility of this pitch-tunable pillar array was demonstrated by evaluating drug distribution and expression levels of several proteins following drug treatment in 3D tumor spheroids. Overall, our mini-pillar array provides a novel platform that can be useful for culturing tumor spheroids as well as for immunohistological analysis in a multiplexed and high throughput manner.

Charge Transport in 2D DNA Tunnel Junction Diodes.

Recently, deoxyribonucleic acid (DNA) is studied for electronics due to its intrinsic benefits such as its natural plenitude, biodegradability, biofunctionality, and low-cost. However, its applications are limited to passive components because of inherent insulating properties. In this report, a metal-insulator-metal tunnel diode with Au/DNA/NiOx junctions is presented. Through the self-aligning process of DNA molecules, a 2D DNA nanosheet is synthesized and used as a tunneling barrier, and semitransparent conducting oxide (NiOx ) is applied as a top electrode for resolving metal penetration issues. This molecular device successfully operates as a nonresonant tunneling diode, and temperature-variable current-voltage analysis proves that Fowler-Nordheim tunneling is a dominant conduction mechanism at the junctions. DNA-based tunneling devices appear to be promising prototypes for nanoelectronics using biomolecules.

New record of Castanopsides falkovitshi Kerzhner from Korea (Heteroptera: Miridae: Mirinae: Mirini).

BACKGROUND: The genus Castanopsides Yasunaga, 1992 belongs to the subfamily Mirinae and comprises 11 species worldwide. Prior to this study, two species, C. kerzhneri Josifov and C. potanini Reuter has been recorded from the Korean Peninsula. The genus Castanopsides Yasunaga, 1992 belongs to the subfamily Mirinae and comprises 11 species worldwide. Prior to this study, two species, C. kerzhneri Josifov and C. potanini Reuter has been recorded from the Korean Peninsula. NEW INFORMATION: In this paper, three species are recognized including a new record, C. falkovitshi (Kerzhner, 1979). Images of dorsal and ventral habitus, and male and genitalic structures are provided. A key to the Korean Castanopsides species is presented.

Crack-induced Ag nanowire networks for transparent, stretchable, and highly sensitive strain sensors.

Crack-based strain sensor systems have been known for its high sensitivity, but suffer from the small fracture strain of the thin metal films employed in the sensor which results in its negligible stretchability. Herein, we fabricated a transparent (>90% at 550 nm wavelength), stretchable (up to 100%), and sensitive (gauge factor (GF) of 30 at 100% strain) strain gauge by depositing an encapsulated crack-induced Ag nanowire (AgNW) network on a hydroxylated poly(dimethylsiloxane) (PDMS) film. Stretching the encapsulated AgNWs/PDMS resulted in the formation of a percolation network of nanowire ligaments with abundant percolation paths. The encapsulating polymer was designed to adhere strongly to both the AgNW and PDMS. The improved adhesion ensured the resistance of the crack-induced network of AgNWs varied reversibly, stably, and sensitively when stretched and released, at strains of up to 100%. The developed sensor successfully detected human motions when applied to the skin.

Flexible and Wavelength-Selective MoS2 Phototransistors with Monolithically Integrated Transmission Color Filters.

Color-selective or wavelength-tunable capability is a crucial feature for two-dimensional (2-D) semiconducting material-based image sensor applications. Here, we report on flexible and wavelength-selective molybdenum disulfide (MoS2) phototransistors using monolithically integrated transmission Fabry-Perot (F-P) cavity filters. The fabricated multilayer MoS2 phototransistors on a polyarylate substrate exhibit decent electrical characteristics (µFE > 64.4 cm2/Vs, on/off ratio > 106), and the integrated F-P filters, being able to cover whole visible spectrum, successfully modulate the spectral response characteristics of MoS2 phototransistors from ~495 nm (blue) to ~590 nm (amber). Furthermore, power dependence of both responsivity and specific detectivity shows similar trend with other reports, dominated by the photogating effect. When combined with large-area monolayer MoS2 for optical property enhancement and array processing, our results can be further developed into ultra-thin flexible photodetectors for wearables, conformable image sensor, and other optoelectronic applications.

Optically transparent thin-film transistors based on 2D multilayer MoS2 and indium zinc oxide electrodes.

We report on optically transparent thin film transistors (TFTs) fabricated using multilayered molybdenum disulfide (MoS2) as the active channel, indium tin oxide (ITO) for the back-gated electrode and indium zinc oxide (IZO) for the source/drain electrodes, respectively, which showed more than 81% transmittance in the visible wavelength. In spite of a relatively large Schottky barrier between MoS2 and IZO, the n-type behavior with a field-effect mobility (µ(eff)) of 1.4 cm(2) V(-1) s(-1) was observed in as-fabricated transparent MoS2 TFT. In order to enhance the performances of transparent MoS2 TFTs, a picosecond pulsed laser was selectively irradiated onto the contact region of the IZO electrodes. Following laser annealing, µ(eff) increased to 4.5 cm(2) V(-1) s(-1), and the on-off current ratio (I(on)/I(off)) increased to 10(4), which were attributed to the reduction of the contact resistance between MoS2 and IZO.

Direct patterning of poly(acrylic acid) on polymer surfaces by ion beam lithography for the controlled adhesion of mammalian cells.

Poly(acrylic acid) (PAA)-patterned polystyrene (PS) substrates were prepared by ion beam lithography to control cell behaviors of mouse fibroblasts and human embryonic kidney cells. Thin PAA films spin-coated on non-biological PS substrates were selectively irradiated with energetic proton ions through a pattern mask. The irradiated substrates were developed with deionized water to generate negative-type PAA patterns. The surface characteristics of the resulting PAA-patterned PS surface, such as surface morphology, chemical structure and composition and wettability, were investigated. Well-defined 100 µm PAA patterns were effectively formed on relatively hydrophobic PS substrates by ion beam lithography at higher fluences than 5 × 10(14) ions/cm(2). Moreover, based on the in vitro cell culture test, cells were adhered and proliferated favorably onto hydrophilic PAA regions separated by hydrophobic PS regions on the PAA-patterned PS substrates, and thereby leading to the formation of well-defined cell patterns.

Semitransparent quantum dot light-emitting diodes by cadmium-free colloidal quantum dots.

The InP/ZnSe/ZnS multishell colloidal quantum dots (QDs) were prepared by convenient heating-up method for an emission layer of semitransparent quantum dot light-emitting diodes (QD-LEDs). The synthesized InP/ZnSe/ZnS multishell QDs exhibited an emission peak at 545 nm for clear green color with a full-width at half-maximum (FWHM) of 50 nm, and photoluminescent (PL) quantum yield (QY) of 45%. The multishell on the indium phosphide (InP) core helped increasing QY and stability by reducing interfacial defects. Using a Ca/Ag cathode, the whole QD-LEDs were semitransparent throughout the visible wavelengths. The maximum brightness and currernt efficiency of semitransparent QD-LEDs reached 587 cd/m2 and 1.52 cd/A by controlling the thickness of Ca/Ag cathode, which is comparable to the device with opaque LiF/Al cathode (1444 cd/m2 and 1.98 cd/A). The performance of our semitransparent and eco-friendly device is not matched with traditional cadmium (Cd) based QD-LEDs yet, but it shows the great potential for various window-type information displays.

Flexible metal-oxide devices made by room-temperature photochemical activation of sol-gel films.

Amorphous metal-oxide semiconductors have emerged as potential replacements for organic and silicon materials in thin-film electronics. The high carrier mobility in the amorphous state, and excellent large-area uniformity, have extended their applications to active-matrix electronics, including displays, sensor arrays and X-ray detectors. Moreover, their solution processability and optical transparency have opened new horizons for low-cost printable and transparent electronics on plastic substrates. But metal-oxide formation by the sol-gel route requires an annealing step at relatively high temperature, which has prevented the incorporation of these materials with the polymer substrates used in high-performance flexible electronics. Here we report a general method for forming high-performance and operationally stable metal-oxide semiconductors at room temperature, by deep-ultraviolet photochemical activation of sol-gel films. Deep-ultraviolet irradiation induces efficient condensation and densification of oxide semiconducting films by photochemical activation at low temperature. This photochemical activation is applicable to numerous metal-oxide semiconductors, and the performance (in terms of transistor mobility and operational stability) of thin-film transistors fabricated by this route compares favourably with that of thin-film transistors based on thermally annealed materials. The field-effect mobilities of the photo-activated metal-oxide semiconductors are as high as 14 and 7 cm(2) V(-1) s(-1) (with an Al(2)O(3) gate insulator) on glass and polymer substrates, respectively; and seven-stage ring oscillators fabricated on polymer substrates operate with an oscillation frequency of more than 340 kHz, corresponding to a propagation delay of less than 210 nanoseconds per stage.