Ink Formulation and Printing Parameters for Inkjet Printing of Two Dimensional Materials: A Mini Review.

Inkjet printing of two-dimensional (2D) material has been a center of interest for wearable electronics and has become a promising platform for next-generation technologies. Despite the enormous progress made in printed 2D materials, there are still challenges in finding the optimal printing conditions involving the ink formulation and printing parameters. Adequate ink formulation and printing parameters for target 2D materials rely on empirical studies and repeated trials. Therefore, it is essential to compile promising strategies for ink formulation and printing parameters. In this context, this review discusses the optimal ink formulations to prepare stable ink and steady ink jetting and then explores the critical printing parameters for fabricating printed 2D materials of a high quality. The summary and future prospects for inkjet-printed 2D materials are also addressed.

Clumping Between Carbon Black and Titanium Dioxide Pigment by Water Vapor Absorption and Its Correlation with Electrophoretic Display.

Carbon black and titanium dioxide have been widely used as pigment particles for electrophoretic displays. However, the effect of external water vapor on these pigment particles has not yet been presented. Therefore, in this work, we report the clumping phenomenon between pigment particles as a result of water vapor absorption. To verify clumping between pigment particles, various analysis techniques were used, including scanning electron microscopy, atomic force microscopy, zeta potential measurement, and Raman spectroscopy. We examined the Raman spectrum of carbon black to demonstrate the effect of water vapor absorption on particles. According to the Raman spectrum analysis, the 2D and 2D' peak intensities were significantly increased; moreover, the full widths at half maximum were modified. Thus, we concluded that water vapor absorption on pigment particles can induce the clumping phenomenon on pigments. To protect an electrophoretic display device from external gas transmission, we applied a nanocomposites gas barrier film to the device. The device lifetime was consequently improved by 336%.

Fabrication of graphene oxide/montmorillonite nanocomposite flexible thin films with improved gas-barrier properties.

Nanocomposites are potential substitutes for inorganic materials in fabricating flexible gas-barrier thin films. In this study, two nanocomposites are used to form a flexible gas-barrier film that shows improved flexibility and a decreased water vapor transmission rate (WVTR), thereby extending the diffusion path length for gas molecules. The nanoclay materials used for the flexible gas-barrier thin film are Na+-montmorillonite (MMT) and graphene oxide (GO). A flexible gas-barrier thin film was fabricated using a layer-by-layer (LBL) deposition method, exploiting electronic bonding under non-vacuum conditions. The WVTR of the film, in which each layer was laminated by LBL assembly, was analyzed by Ca-test and the oxygen transmission rate (OTR) was analyzed by MOCON. When GO and MMT are used together, they fill each other's vacancies and form a gas-barrier film with high optical transmittance and the improved WVTR of 3.1 × 10-3 g per m2 per day without a large increase in thickness compared to barrier films produced with GO or MMT alone. Thus, this film has potential applicability as a barrier film in flexible electronic devices.

Hydrolyzed hexagonal boron nitride/polymer nanocomposites for transparent gas barrier film.

A flexible thin gas barrier film formed by layer-by-layer (LBL) assembly has been studied. We propose for the first time that hexagonal boron nitride (h-BN) can be used in LBL assembly. When dispersed in water through sonication-assisted hydrolysis, h-BN develops hydroxyl groups that electrostatically couple with the cationic polymer polydiallyldimethylammonium chloride (PDDA). This process produces hydroxyl-functional h-BN/PDDA nanocomposites. The nanocomposites exhibit well exfoliated and highly ordered h-BN nanosheets, which results in an extremely high visual clarity, with an average transmittance of 99% in the visible spectrum. Moreover, well aligned nanocomposites extend gas diffusion path that reduce water vapor transmission rate to 1.3 × 10-2 g m-2 d-1. The simple and fast LBL process demonstrated here can be applied in many gas barrier applications.

Silver Nanowire-IZO-Conducting Polymer Hybrids for Flexible and Transparent Conductive Electrodes for Organic Light-Emitting Diodes.

Solution-processed silver nanowire (AgNW) has been considered as a promising material for next-generation flexible transparent conductive electrodes. However, despite the advantages of AgNWs, some of their intrinsic drawbacks, such as large surface roughness and poor interconnection between wires, limit their practical application in organic light-emitting diodes (OLEDs). Herein, we report a high-performance AgNW-based hybrid electrode composed of indium-doped zinc oxide (IZO) and poly (3,4-ethylenediowythiophene):poly(styrenesulfonate) [PEDOT:PSS]. The IZO layer protects the underlying AgNWs from oxidation and corrosion and tightly fuses the wires together and to the substrate. The PEDOT:PSS effectively reduces surface roughness and increases the hybrid films' transmittance. The fabricated electrodes exhibited a low sheet resistance of 5.9 Ωsq-1 with high transmittance of 86% at 550 nm. The optical, electrical, and mechanical properties of the AgNW-based hybrid films were investigated in detail to determine the structure-property relations, and whether optical or electrical properties could be controlled with variation in each layer's thickness to satisfy different requirements for different applications. Flexible OLEDs (f-OLEDs) were successfully fabricated on the hybrid electrodes to prove their applicability; their performance was even better than those on commercial indium doped tin oxide (ITO) electrodes.

Testicular microlithiasis: prevalence and clinical significance in a population referred for scrotal ultrasonography.

PURPOSE: Testicular microlithiasis (TM) is an uncommon pathologic condition that is commonly diagnosed by scrotal ultrasonography. Indirect evidence suggests that this syndrome may be associated with an increased risk of testicular malignancy and infertility. MATERIALS AND METHODS: A total of 1,439 patients undergoing scrotal ultrasound during a 6-year, 5-month period (January 2003 to May 2009) were retrospectively reviewed. Any possible association of TM with pathologic findings was assessed. Among patients with TM, further grading of TM with testicular cancer and semen analysis of the infertile group with TM were also performed. RESULTS: TM was diagnosed in 87 patients (6.0%) out of a total of 1,439. Of all established pathologic entities, only testicular malignancy and infertility were meaningfully associated with TM. There was no significant difference in the prevalence of testicular cancer between each grade. Seminal profiles (sperm count, motility, morphology, and white blood cell count) were not found to be statistically different between infertile men with and without TM. CONCLUSIONS: The prevalence of TM in symptomatic men was found to be 6.0% with significant co-occurrence of TM, testicular cancer, and infertility. Further grading of TM does not seem to be essential with regard to the detection of patients with testicular cancer and TM. TM showed no significant effect on the seminal profiles of infertile men.

Parkin cleaves intracellular alpha-synuclein inclusions via the activation of calpain.

Mutations in the alpha-synuclein and parkin genes cause heritable forms of Parkinson's disease. In the present study, we examined the possible functional relationship between the parkin and alpha-synuclein genes in a conditionally immortalized embryonic hippocampal cell (H19-7) line. Whereas transient transfection of alpha-synuclein into neuronal H19-7 cells caused the formation of its intracytoplasmic inclusions and a significant cell death, the combined overexpression of parkin restored the alpha-synuclein-induced decrease in cell viability to control levels. In addition, the overexpression of parkin was found to generate selective cleavage of alpha-synuclein. Furthermore, the cytoprotective effect of parkin on alpha-synuclein-induced cell death was not inhibited in the presence of a proteasome inhibitor. Interestingly, the overexpression of parkin induced the activation of an intracellular cysteine protease, calpain, but not caspase, and the cytoprotective effect of parkin on alpha-synuclein cytotoxicity was significantly inhibited by the presence of calpain-specific inhibitors. In conclusion, our results suggest that parkin accelerates the degradation of alpha-synuclein via the activation of the nonproteasomal protease, calpain, leading to the prevention of alpha-synuclein-induced cell death in embryonic hippocampal progenitor cells.