Light-powered wireless manipulation of small objects in fluids has been of interest for biomedical and environmental applications. Although many techniques employing UV−vis−NIR light sources have been devised, new methods that hold greater penetrating power deep into medium are still in demand. Here, we develop a method to exploit X-rays to propel half-metal-coated Janus microparticles in aqueous solution. The Janus particles are simultaneously propelled and visualized in real-time by using a full-field transmission X-ray microscope. Our real-time observation discovers that the propulsive motion follows the bubble growth enhanced by water radiolysis near the particle surface under X-ray irradiation. We also show that the propulsion speed is remotely controlled by varying the radiation dose. We expect this work to open opportunities to employ light-powered micro/ nanomotors in opaque environments, potentially by combining with medical imaging or nondestructive testing.

Organic-inorganic metal halide perovskites, particularly CH 3 NH 3 PbX 3 (X = Cl, Br, and I), have recently emerged as a promising optoelectronic material [1] because of their excellent properties such as large optical absorption, long carrier diffusion length, high carrier mobility, and low-cost solution production process. [2][3][4][5][6] Over the past decade, there have been conducted substantial research to utilize perovskites for diverse applications as solar cells, [2,7,8] photodetectors, [9,10] light emitting diodes, [11,12] and lasers. [13,14] Most of the research has focused on the control over crystallinity or chemical composition in a thin film form, in result, making great advances in material performance. [15][16][17][18][19] Continuous demands on optoelectronic devices with high integration density and new functions have raised the need for nanostructured perovskites. [20] Especially, nanowires, 1D nanostructures with controlled diameters and lengths, are the basic building blocks for creating miniaturized devices. Techniques to fabricate perovskite nanowires mainly rely on i) vapor-phase deposition [21,22] or ii) solution-mediated crystallization. [14,[23][24][25][26] The former offers an excellent crystal quality but lacks the ability to precisely position individual nanowires. In the latter that is based on supersaturation of solutes, there have been several remarkable attempts to fabricate and align individual nanowires by confinement of solution inside templates, [23,24] nanoimprint molds, [25] or nanofluidic channels [26] under evaporation of solvent.Recently, some clever methods based on inkjet printing have been devised for patterning perovskite micro/nanostructures. [27,28] These attempts have enhanced the freedom of nanostructures design beyond straight nanowires, potentially enabling a high-level integration of perovskite circuitries and devices. However, the developed patterning techniques for perovskites are still limited to in-plane fabrication and alignment.Since its invention in the 1980s, 3D printing, known as additive manufacturing, has attracted great attention as a facile method to produce tangible freeform structures. Beyond simple prototyping, there have recently been enormous efforts to improve or diversify the properties of 3D printed objects-for their practical use-by engineering materials' crystallinity [29,30] or molecular orientation. [31][32][33] In this context, owing to their As competing with the established silicon technology, organic-inorganic metal halide perovskites are continually gaining ground in optoelectronics due to their excellent material properties and low-cost production. The ability to have control over their shape, as well as composition and crystallinity, is indispensable for practical materialization. Many sophisticated nanofabrication methods have been devised to shape perovskites; however, they are still limited to in-plane, low-aspect-ratio, and simple forms. This is in stark contrast with the demands of modern optoelectronics with freeform circui...

Exploiting a femtoliter liquid meniscus formed on a nanopipet is a powerful approach to spatially control mass transfer or chemical reaction at the nanoscale. However, the insufficient reliability of techniques for the meniscus formation still restricts its practical use. We report on a noncontact, programmable method to produce a femtoliter liquid meniscus that is utilized for parallel three-dimensional (3D) nanoprinting. The method based on electrohydrodynamic dispensing enables one to create an ink meniscus at a pipet-substrate gap without physical contact and positional feedback. By guiding the meniscus under rapid evaporation of solvent in air, we successfully fabricate freestanding polymer 3D nanostructures. After a quantitative characterization of the experimental conditions, we show that we can use a multibarrel pipet to achieve parallel fabrication process of clustered nanowires with precise placement. We expect this technique to advance productivity in nanoscale 3D printing.

Crystallized p‐type small‐molecule semiconductors have great potential as an efficient and stable hole transporting materials (HTMs) for perovskite solar cells (PSCs) due to their relatively high hole mobility, good stability, and tunable highest occupied molecular orbitals. Here, a thienoacene‐based organic semiconductor, 2,9‐diphenyldinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (DPh‐DNTT), is thermally evaporated and employed as the dopant‐free HTM that can be scaled up for large‐area fabrication. By controlling the deposition temperature, the molecular orientation is modulated into a dominant face‐on orientation with π–π stacking direction perpendicular to the substrate surface, maximizing the out‐of‐plane carrier mobility. With an engineered face‐on orientation, the DPh‐DNTT film shows an improved out‐of‐plane mobility of 3.3 × 10−2 cm2 V−1 s−1, outperforming the HTMs reported so far. Such orientation‐reinforced mobility contributes to a remarkable efficiency of 20.2% for CH3NH3PbI3 inverted PSCs with enhanced stability. The results reported here provide insights into engineering the orientation of molecules for the dopant‐free organic HTMs for PSCs.

Hybrid perovskites are emerging as a promising, high-performance luminescent material; however, the technological challenges associated with generating high-resolution, free-form perovskite structures remain unresolved, limiting innovation in optoelectronic devices. Here, we report nanoscale three-dimensional (3D) printing of colored perovskite pixels with programmed dimensions, placements, and emission characteristics. Notably, a meniscus comprising femtoliters of ink is used to guide a highly confined, out-of-plane crystallization process, which generates 3D red, green, and blue (RGB) perovskite nanopixels with ultrahigh integration density. We show that the 3D form of these nanopixels enhances their emission brightness without sacrificing their lateral resolution, thereby enabling the fabrication of high-resolution displays with improved brightness. Furthermore, 3D pixels can store and encode additional information into their vertical heights, providing multilevel security against counterfeiting. The proof-of-concept experiments demonstrate the potential of 3D printing to become a platform for the manufacture of smart, high-performance photonic devices without design restrictions.

Experimental and numerical investigations on the interaction of a planar shock wave with two-dimensional (2-D) and three-dimensional (3-D) light gas cylinders are performed. The effects of initial interface curvature on flow morphology, wave pattern, vorticity distribution and interface movement are emphasized. In experiments, a wire-restriction method based on the soap film technique is employed to generate N$_{2}$ cylinders surrounded by SF$_{6}$ with well-characterized shapes, including a convex cylinder, a concave cylinder with a minimum-surface feature and a 2-D cylinder. The high-speed schlieren pictures demonstrate that fewer disturbance waves exist in the flow field and the evolving interfaces develop in a more symmetrical way relative to previous studies. By combining the high-order weighted essentially non-oscillatory construction with the double-flux scheme, numerical simulation is conducted to explore the detailed 3-D flow structures. It is indicated that the shape and the size of 3-D gas cylinders in different planes along the vertical direction change gradually due to the existence of both horizontal and vertical velocities of the flow. At very early stages, pressure oscillations in the vicinity of evolving interfaces induced by complex waves contribute much to the deformation of the 3-D gas cylinders. As time proceeds, the development of the shocked volume would be dominated by the baroclinic vorticity deposited on the interface. In comparison with the 2-D case, the oppositely (or identically) signed principal curvatures of the concave (or convex) SF$_{6}$/N$_{2}$ boundary cause complex high pressure zones and additional vorticity deposition, and the upstream interface from the symmetric slice of the concave (or convex) N$_{2}$ cylinder moves with an inhibition (or a promotion). Finally, a generalized 3-D theoretical model is proposed for predicting the upstream interface movements of different gas cylinders and the present experimental and numerical findings are well predicted.

The APETALA 2/ethylene response factors (AP2/ERF) are widespread in the plant kingdom and play essential roles in regulating plant growth and development as well as defense responses. In this study, a novel rice AP2/ERF transcription factor gene, OsRPH1, was isolated and functionally characterized. OsRPH1 falls into group-IVa of the AP2/ERF family. OsRPH1 protein was found to be localized in the nucleus and possessed transcriptional activity. Overexpression of OsRPH1 resulted in a decrease in plant height and length of internode and leaf sheath as well as other abnormal characters in rice. The length of the second leaf sheath of OsRPH1-overexpressing (OE) plants recovered to that of Kitaake (non-transgenic recipient) in response to exogenous gibberellin A 3 (GA 3) application. The expression of GA biosynthesis genes (OsGA20ox1-OsGA20ox4, OsGA3ox1, and OsGA3ox2) was significantly downregulated, whereas that of GA inactivation genes (OsGA2ox7, OsGA2ox9, and OsGA2ox10) was significantly upregulated in OsRPH1-OE plants. Endogenous bioactive GA contents significantly decreased in OsRPH1-OE plants. OsRPH1 interacted with a blue light receptor, OsCRY1b, in a blue light-dependent manner. Taken together, our results demonstrate that OsRPH1 negatively regulates plant height and bioactive GA content by controlling the expression of GA metabolism genes in rice. OsRPH1 is involved in blue light inhibition of leaf sheath elongation by interacting with OsCRY1b.

Cold stress is one of the most important abiotic stresses in rice. C2H2 zinc finger proteins play important roles in response to abiotic stresses in plants. In the present study, we isolated and functionally characterized a new C2H2 zinc finger protein transcription factor OsCTZFP8 in rice. OsCTZFP8 encodes a C2H2 zinc finger protein, which contains a typical zinc finger motif, as well as a potential nuclear localization signal (NLS) and a leucine-rich region (L-box). Expression of OsCTZFP8 was differentially induced by several abiotic stresses and was strongly induced by cold stress. Subcellular localization assay and yeast one-hybrid analysis revealed that OsCTZFP8 was a nuclear protein and has transactivation activity. To characterize the function of OsCTZFP8 in rice, the full-length cDNA of OsCTZFP8 was isolated and transgenic rice with overexpression of OsCTZFP8 driven by the maize ubiquitin promoter was generated using Agrobacterium-mediated transformation. Among 46 independent transgenic lines, 6 single-copy homozygous overexpressing lines were selected by Southern blot analysis and Basta resistance segregation assay in both T1 and T2 generations. Transgenic rice overexpressing OsCTZFP8 exhibited cold tolerant phenotypes with significantly higher pollen fertilities and seed setting rates than nontransgenic control plants. In addition, yield per plant of OsCTZFP8-expressing lines was significantly (p < 0.01) higher than that of nontransgenic control plants under cold treatments. These results demonstrate that OsCTZFP8 was a C2H2 zinc finger transcription factor that plays an important role in cold tolerance in rice.