Humidity-Tolerant Moisture-Driven Energy Generator with MXene Aerogel-Organohydrogel Bilayer.

Free-standing and film-type moisture-driven energy generators (MEGs) that harness the preferential interaction of ionized moisture with hydrophilic materials are interesting because of their wearability and portability without needing a water container. However, most such MEGs work in limited humidity conditions, which provide a substantial moisture gradient. Herein, we present a high-performance MEG with sustainable power-production capability in a wide range of environments. The bilayer-based device comprises a negatively surface-charged, hydrophilic MXene (Ti3C2Tx) aerogel and polyacrylamide (PAM) ionic hydrogel. The preferential selection on the MXene aerogel of positive charges supplied from the salts and water in the hydrogel is predicted by the first-principle simulation, which results in a high electric output in a wide relative humidity range from 20% to 95%. Furthermore, by replacing the hydrogel with an organohydrogel of PAM that has excellent water retention and structural stability, a device with long-term electricity generation is realized for more than 15 days in a broad temperature range (from -20 to 80 °C). Our MXene aerogel MEGs connected in series supply sufficient power for commercial electronic components in various outdoor environments. Moreover, an MXene aerogel MEG works as a self-powered sensor for recognizing finger bending and facial expression.

Wireless Stand-Alone Trimodal Interactive Display Enabled by Direct Capacitive Coupling.

With recent advances in interactive displays, the development of a stand-alone interactive display with no electrical interconnection is of great interest. Here, a wireless stand-alone interactive display (WiSID), enabled by direct capacitive coupling, consisting of three layers: two in-plane metal electrodes separated by a gap, a composite layer for field-induced electroluminescence (EL) and inverse piezoelectric sound, and a stimuli-responsive layer, from bottom to top, is presented. Alternating current power necessary for field-induced EL and inverse piezoelectric sound is wirelessly transferred from a power unit, with two in-plane electrodes remotely separated from the WiSID. The unique in-plane power transfer through the stimuli-sensitive polar bridge allows stand-alone operation of the WiSID, making it suitable for the wireless dynamic monitoring of medical fluids. Moreover, a haptic wireless stand-alone trimodal interactive display mounted on a human finger is demonstrated, whereby touch is wirelessly displayed in various outputs of EL, inverse piezoelectric sound, and tactile vibration, making it suitable for a wireless three-mode smart braille display.

Visualization of nonsingular defect enabling rapid control of structural color.

Stimuli-interactive structural color (SC) of a block copolymer (BCP) photonic crystal (PC) uses reversible alteration of the PC using external fluids and applied forces. The origin of the diffusional pathways of a stimulating fluid into a BCP PC has not been examined. Here, we directly visualize the vertically oriented screw dislocations in a one-dimensional lamellar BCP PC that facilitate the rapid response of visible SC. To reveal the diffusional pathway of the solvent via the dislocations, BCP lamellae are swollen with an interpenetrated hydrogel network, allowing fixation of the swollen state and subsequent microscopic examination. The visualized defects are low-energy helicoidal screw dislocations having unique, nonsingular cores. Location and areal density of these dislocations are determined by periodic concentric topographic nanopatterns of the upper surface-reconstructed layer. The nonsingular nature of the interlayer connectivity in the core region demonstrates the beneficial nature of these defects on sensing dynamics.

Polymer-Laminated Ti3C2TX MXene Electrodes for Transparent and Flexible Field-Driven Electronics.

MXenes (Ti3C2TX) are two-dimensional transition-metal carbides and carbonitrides with high conductivity and optical transparency. However, transparent MXene electrodes with high environmental stability suitable for various flexible organic electronic devices have rarely been demonstrated. By laminating a thin polymer film onto a solution-processed MXene layer to protect the MXene film from harsh environmental conditions, we present transparent and flexible MXene electronic devices. A thin polymer layer spin-coated onto a transparent MXene electrode provides environmental stability even under air exposure longer than 7 d at high temperatures (up to 70 °C) and humidity levels (up to 50%) without degrading the transparency of the electrode. The resulting polymer-laminated (PL) MXene electrode facilitates the development of a variety of field-driven photoelectronic devices by exploiting the electric field exerted between the MXene layer and the counter electrode through the insulating polymer. Field-induced electroluminescent displays, based on both organic and inorganic phosphors, with PL-MXene electrodes are demonstrated with high transparency and mechanical flexibility. Furthermore, our PL-MXene electrode exhibits high versatility through successful implementation in capacitive-type pressure sensors and triboelectric nanogenerators, resulting in field-driven sensing and energy harvesting electronic devices with excellent operation reliability.

Trends in the rates of peripartum hysterectomy and uterine artery embolization.

The objective of this study was to determine the trends in national rates of peripartum hysterectomy (PH) and uterine arterial embolization (UAE) in Korea. We used data collected by the Health Insurance Review & Assessment Service of Korea and analyzed data from patients who gave birth during the period from 2005 to 2008. There were 1785,178 deliveries during the study period, including 2636 cases of PH (1.48 per 1000 deliveries). The PH rate in 2005 was 1.57 per 1000 deliveries and in 2008 it was 1.33 per 1000 deliveries. UAE was performed in 161 women (incidence, 0.38 per 1000 deliveries) and 447 women (incidence, 0.98 per 1000 deliveries) in 2005 and 2008, respectively. In Korea, the rate of PH decreased slightly, while the rate of UAE rate increased dramatically during the period from 2005 to 2008. Further studies are needed to evaluate the effects of UAE on the rate of PH performed.

The tobacco gene Ntcyc07 confers arsenite tolerance in Saccharomyces cerevisiae by reducing the steady state levels of intracellular arsenic.

We cloned a plant gene, Ntcyc07, conferring arsenite tolerance by expressing a tobacco expression library in WT yeast (Y800). Expression of Ntcyc07 increased the tolerance to As(III) and decreased its accumulation, suggesting that the enhanced As(III) tolerance resulted from a reduction of the intracellular arsenic level. Interestingly, expression of Ntcyc07 increased the expression of the As(III) export carrier ACR3, but repressed that of As(III) uptake channel FPS1. Ntcyc07p interacted with Acr1p, which is the transcriptional activator of ACR3, but not with the ACR3 promoter. Taken together, the data indicated that Ntcyc07p promoted As(III) tolerance by decreasing the intracellular level of As(III) via increasing the expression of ACR3 and reducing that of FPS1.

Expression of yeast transcriptional activator MSN1 promotes accumulation of chromium and sulfur by enhancing sulfate transporter level in plants.

MSN1 is a putative yeast transcriptional activator involved in chromium (Cr) accumulation. Here we show that overexpression of MSN1 enhances Cr and sulfur accumulation and Cr tolerance in transgenic tobacco. In addition, we found that expression of NtST1 (Nicotiana tabacum sulfate transporter 1) was elevated in MSN1- expressing transgenic tobacco, suggesting that chromate and sulfate are taken up via the sulfate transporter in plants. Supporting this, expression of NtST1 increased levels of Cr and S in Saccharomyces cerevisiae. Our findings suggest that yeast transcriptional activators can be used for developing effective metal remediators, and for improving the nutritional status of plants.

The putative transcriptional activator MSN1 promotes chromium accumulation in Saccharomyces cerevisiae.

Yeast is a good system for studying molecular mechanisms of metal tolerance. Using a mini-Tn mutagenized yeast pool, we isolated a chromate-tolerant mutant, CrT9, that displayed metal-specific tolerance since it was only tolerant to Cr(VI), not to Cr(III), Cd, As, or Fe. The Cr-tolerance of CrT9 appeared to be due to reduced Cr accumulation as it accumulated only 56% as much as WT (Y800). Using IPCR (inverse PCR), we found that the mini-Tn had been inserted at nt 741 of the transcriptional activator, MSN1. MSN1 is a multifunctional protein involved in invertase activity, iron uptake, starch degradation, pseudohyphal growth, and osmotic gene expression. We found that there was only one mini-Tn insertion in CrT9 since MSN1 and mini-Tn probes hybridized to the same DNA fragment, and the MSN1 probe detected an enlarged MSN1 mRNA. When we over-expressed MSN1 in CrT9 and WT, both accumulated larger amounts of Cr. We conclude that Cr accumulation in S. cerevisiae is promoted by the transcriptional activator MSN1.