A role of cryptochrome for magnetic field-dependent improvement of sleep quality, lifespan, and motor function in Drosophila.

Understanding the molecular genetic basis of animal magnet reception has been one of the big challenges in molecular biology. Recently it was discovered that the magnetic sense of Drosophila melanogaster is mediated by the ultraviolet (UV)-A/blue light photoreceptor cryptochrome (Cry). Here, using the fruit fly as a magnet-receptive model organism, we show that the magnetic field exposure (0.4-0.6 mT) extended lifespan under starvation, but not in cryptochrome mutant flies (cryb ). The magnetic field exposure increases motor function in wild type and neurodegenerative disease model flies. Furthermore, the magnetic field exposure improved sleep quality at night-time specific manner, but not in cryb . We also showed that repeated AC magnetic field exposure increased climbing activity in wild-type Drosophila, but not in cryb . The data suggests that magnetic field-dependent improvement of lifespan, sleep quality, and motor function is mediated through a cry-dependent pathway in Drosophila.

Formation Mechanism of Elemental Te Produced in Tellurite Glass Systems by Femtosecond Laser Irradiation.

The formation of elemental trigonal tellurium (t-Te) on tellurite glass surfaces exposed to femtosecond laser pulses is discussed. Specifically, the underlying elemental crystallization phenomenon is investigated by altering laser parameters in common tellurite glass compositions under various ambient conditions. Elemental crystallization of t-Te by a single femtosecond laser pulse is unveiled by high-resolution imaging and analysis. The thermal diffusion model reveals the absence of lattice melting upon a single laser pulse, highlighting the complexity of the phase transformation. The typical cross-section displays three different crystal configurations over its depth, in which the overall thickness increases with each subsequent pulse. The effect of various controlled atmospheres shows the suppressing nature of the elemental crystallization, whereas the substrate temperature shows no significant impact on the nucleation of t-Te nanocrystals. This research gives new insight into the elemental crystallization of glass upon femtosecond laser irradiation and shows the potential to fabricate functional transparent electronic micro/nanodevices.

Novel Bending Sensor Based on a Solution-Processed Cu2O Film with High Resolution Covering a Wide Curvature Range.

A Cu2O film is prepared on a flexible polyethylene terephthalate substrate for a bending sensor using the spin-spray method, a facile and low-environmental-load solution process. The Cu2O bending sensor shows high sensitivity and high resolution not only over a wide range of curvatures (0 < κ < 0.21 mm-1) but also for very small curvature changes (Δκ = ∼ 0.03 mm-1). The bending response of the sensor exhibited a curvature change of high linearity with a good gauge factor (18.2) owing to the grain-boundary resistance and piezoresistive effects of the fabricated Cu2O film. In addition, the sensor possesses good repeatability, stability, and long-term (>30 days) and mechanical fatigue durability (1000 bending-release cycles). The sensor is capable of detailed monitoring of large- and small-scale human motions, such as finger bending, wrist bending, nodding, mouth opening/closing, and swallowing. In addition, excellent stability and repeatability of the monitoring performance is observed over a wide range of motion angles and speeds. All of these results demonstrate the potential of the flexible bending sensor based on the Cu2O film as a candidate for healthcare monitoring and wearable electronics.

In Situ Assembling of Glass Microspheres and Bonding Force Analysis by the Ultraviolet-Near-Infrared Dual-Beam Optical Tweezer System.

Microresonators show great potential as interlayer routing solutions for multilayered three-dimensional (3D) photonic communication networks. New techniques are needed for the convenient and in situ manipulation and immobilization of glass microspheres into functional structures. Herein, near-infrared (NIR) and ultraviolet (UV) lasers were used as optical tweezers to precisely arrange silica microspheres and UV-initiated immobilization in a 3D space. The NIR laser was used to trap targeted microspheres, and the UV laser was focused to immobilize the trapped microspheres in 3-methacryloxypropyltrimethoxysilane (MOPS) in ∼6 s. Optical force spectroscopy was performed using the optical tweezers to measure individual bond strength. Next, functional triangular pedestals were designed to flexibly control the gap space for vertical router applications in 3D photonic networks. Thus, the designed UV-NIR dual-beam optical tweezer system can be used to assemble arbitrary functional 3D structures, making it a valuable tool for microfabrication, photonics, and optical communication applications.

Broadband mid-infrared amplified spontaneous emission from Er/Dy co-doped fluoride fiber with a simple diode-pumped configuration.

Er3+/Dy3+ co-doped double-clad ZBLAN optical fiber has been used to obtain amplified spontaneous emission (ASE) broadband light sources cladding-pumped by 980-nm multimode laser diode (LD) sources. It has been demonstrated that mid-infrared broadband emission extending from 2515 to 3735 nm was obtained by energy transfer between Er3+ and Dy3+. We experimentally investigated the optimum design of Er3+/Dy3+ co-doped ZBLAN fiber in terms of ion concentration, fiber length, pumping configuration, and pumping power. The ASE output power was more than 2.5 mW when the LD pump power was set at 5 W. To assess its potential for gas sensing applications, the fabricated ASE light source was used to successfully detect methane gas with concentrations at 1% and 5%. The simple and stable construction of our ASE light source is suitable for practical purposes.

Compositional redistribution in CaO-Al2O3-SiO2 glass induced by the migration of a steel microsphere due to continuous-wave-laser irradiation.

A high-power continuous-wave (CW) laser was used to move a steel microsphere through a CaO-Al2O3-SiO2 glass block at room temperature along a trajectory toward the laser source. A compositional analysis revealed that the CaO concentration in the glass decreased at the center of the microsphere's trajectory but increased in the area adjacent to it; the SiO2 concentration showed an opposite trend while the Al2O3 concentration did not change. Further, the compositional difference between the center and the area adjacent to the microsphere trajectory depends on the velocity of the microsphere, which is controllable by tuning the laser power.

Anisotropic growth of gas-liquid precipitated ceria mesocrystals to wires several micrometers in length.

Ceria (CeO2) wires with lengths of 6 µm and diameters of tens of nanometers are fabricated through the anisotropic growth of mesocrystals. In the gas-liquid precipitation process, an aqueous Ce(NO3)3 solution is used as a starting material and NH3 gas is used to induce CeO2 precipitation at the gas-liquid interface. CeO2 mesocrystals, formed by this process at 60 °C, grow in the direction of 〈011〉 into micrometer length wires exposing {001} and {011} on their side walls. It is shown that the initial pH of the starting material solution is a key parameter to attain anisotropic growth of the CeO2 mesocrystals. We thus propose the formation mechanism of micrometer length-CeO2 wires from mesocrystals.

Fabrication of nitrogen-doped ZnO nanorod arrays by hydrothermal synthesis and ambient annealing.

Nitrogen-doped ZnO nanorod arrays (N:ZnO NRAs) were fabricated by hydrothermal synthesis using a zinc-ammine complex solution, followed by annealing at elevated temperatures under ambient conditions. After annealing at 400 °C for 1 h, Raman spectra indicated that nitrogen was incorporated in the ZnO crystal structure. NH3-ligands in the zinc-ammine complex precursor were incorporated in ZnO crystals during hydrothermal crystal growth and were then ruptured during annealing. Photoluminescence spectra indicated that during post-annealing, the nitrogen was incorporated into the oxygen site, which created accompanying defects such as oxygen vacancies and/or interstitial oxygen. The absorption edge in diffuse-reflectance UV-visible spectra revealed visible absorption after post-annealing. In addition, the N:ZnO NRAs generated strong visible-light-induced photocurrents. Nitrogen doping caused a decline in carrier density, as confirmed by an electrochemical Mott-Schottky plot. These results suggest that this cost-effective fabrication has many potential applications such as solar-induced water splitting.

A solution-processed tin dioxide film applicable as a transparent and flexible humidity sensor.

An all-solution-processed transparent tin oxide (SnO2)-based humidity sensor was directly prepared on borosilicate glass (SnO2-G) and a flexible polyethylene terephthalate (SnO2-PET) substrate without using a template. The entire process included film deposition by a spin-spray process at 90 °C and subsequent hot water treatment (HWT) at 100 °C. The resistivity of the films dramatically decreased and had semiconductor characteristics after the HWT, even though the as-prepared SnO2-G and SnO2-PET samples were insulators. Based on the results, the variation of the resistivity could be attributed to the formation of a hydroxyl layer on the crystallized SnO2 surface. With the help of the HWT on the SnO2 films, the formation of tin hydroxyl derivatives provided mobile protons, which led to the variation of the electrical properties of SnO2 at ambient conditions with different humidities. The sensitivity of the SnO2-G-HWT and SnO2-PET-HWT at 95% relative humidity (RH) was 35.2 and 3.5 times higher, respectively, than that at 5% RH. Both the sensitivity of the SnO2-G-HWT and SnO2-PET-HWT samples showed a good uptrend corresponding to the increase of RH at 20 ± 1 °C, and the response/recovery time of SnO2-G-HWT and SnO2-PET-HWT was 51/38 s and 69/47 s in the % RH range of 30-70% at 20 ± 1 °C, respectively.

Experimental and theoretical study on the driving force and glass flow by laser-induced metal sphere migration in glass.

Light is able to remotely move matter. Among various driving forces, laser-induced metal sphere migration in glass has been reported. The temperature on the laser-illuminated side of the sphere was higher than that on the non-illuminated side. This temperature gradient caused non-uniformity in the interfacial tension between the glass and the melted metal as the tension decreased with increasing temperature. In the present study, we investigated laser-induced metal sphere migration in different glasses using thermal flow calculations, considering the temperature dependence of the material parameters. In addition, the velocity of the glass flow generated by the metal sphere migration was measured and compared with thermal flow calculations. The migration velocity of the stainless steel sphere increased with increasing laser power density; the maximum velocity was 104 µm/s in borosilicate glass and 47 µm/s in silica glass. The sphere was heated to more than 2000 K. The temperature gradient of the interfacial tension between the stainless steel sphere and the glass was calculated to be -2.29 × 10-5 N/m/K for borosilicate glass and -2.06 × 10-5 N/m/K for silica glass. Glass flowed in the region 15-30 µm from the surface of the sphere, and the 80-µm sphere migrated in a narrow softened channel.

Quasi-single mode laser output from a terrace structure added on a Nd(3+)-doped tellurite-glass microsphere prepared using localized laser heating.

A Nd(3+)-doped tellurite-glass terrace microsphere was fabricated, and its laser characteristics using free-space pumping were investigated. A localized laser heating technique was used for preparing the 29-µm-diameter microsphere. The uncoated sphere exhibited many laser lines with 1.3-mW threshold. Fewer laser lines were observed after terrace formation. The terrace microsphere's lasing threshold was 0.6-2.4 mW depending on the pumping position in the terrace. These results indicate that the terrace structure can modify the modes of a microsphere laser and decrease the laser threshold due to an increase in the coupling efficiency between the cavity and free-space beam.

Laser-assisted morphing of complex three dimensional objects.

Morphing refers to the smooth transition from a specific shape into another one, in which the initial and final shapes can be significantly different. A typical illustration is to turn a cube into a sphere by continuous change of shape curvatures. Here, we demonstrate a process of laser-induced morphing, driven by surface tension and thermally-controlled viscosity. As a proof-of-concept, we turn 3D glass structures fabricated by a femtosecond laser into other shapes by locally heating up the structure with a feedback-controlled CO2 laser. We further show that this laser morphing process can be accurately modelled and predicted.