Genetic dissection of cold tolerance at the budding stage of rice in an indica-japonica recombination inbred line population.

Rice is highly cold-sensitive, and thus, the promotion of cold resistance in buds is essential. In this study, we conducted a mapping analysis to identify quantitative trait loci (QTLs) associated with cold tolerance in buds. The analysis was performed using a recombinant inbred line (RIL) population consisting of 192 lines derived from the cold-tolerant strain 02428 and the cold-sensitive strain YZX. Seven additive loci on chromosomes 1, 4, 5, and 6 were identified, of which loci 3 and 7 were found in two crop seasons, indicating stability. Three epistatic interactions, one present over two seasons, were found. Loci 3 and 7 pyramided with two main-effect QTLs observed to control the rate of low-temperature germination in our previous study. Two materials with good cold resistance at the germination and bud stages were obtained, namely, G93 and G146. Transcriptome sequencing analysis of the two parent buds after cold treatment found that genes expressed differentially between the two parents were related to photosynthesis, energy metabolism, and reactive oxygen scavenging. Five candidate genes, namely, Os01g0385400, Os01g0388000, Os06g0287700, Os06g0289200, and Os06g0291100, were selected in the two stable intervals based on gene expression profiles and annotations. These genetic loci exhibit strong potential as targets for breeding cold tolerance in buds and require additional investigation. In conclusion, this work provides valuable genetic resources that can be utilized to improve the cold tolerance of rice.

Terahertz Bessel metalens with an extended non-diffractive length and a high efficiency.

In this paper, we propose a reflective terahertz (THz) Bessel metalens that utilizes polarization-insensitive sub-wavelength metal resonator-dielectric-metal structures. The Bessel metalens is configured with the superposition of hyperboloidal and conical phase profiles, resulting in a high-efficiency and long non-diffractive length Bessel beam. Our experimental results demonstrate that the proposed Bessel metalens has a focusing efficiency of 72.1% and a non-diffractive length of 239λ. This device has promising aspects in the fields of THz imaging systems and other miniaturized and integrated scenes that require non-diffractive Bessel beams.

A monolithically integrated microcantilever biosensor based on partially depleted SOI CMOS technology.

This paper presents a monolithically integrated aptasensor composed of a piezoresistive microcantilever array and an on-chip signal processing circuit. Twelve microcantilevers, each of them embedded with a piezoresistor, form three sensors in a Wheatstone bridge configuration. The on-chip signal processing circuit consists of a multiplexer, a chopper instrumentation amplifier, a low-pass filter, a sigma-delta analog-to-digital converter, and a serial peripheral interface. Both the microcantilever array and the on-chip signal processing circuit were fabricated on the single-crystalline silicon device layer of a silicon-on-insulator (SOI) wafer with partially depleted (PD) CMOS technology followed by three micromachining processes. The integrated microcantilever sensor makes full use of the high gauge factor of single-crystalline silicon to achieve low parasitic, latch-up, and leakage current in the PD-SOI CMOS. A measured deflection sensitivity of 0.98 × 10-6 nm-1 and an output voltage fluctuation of less than 1 µV were obtained for the integrated microcantilever. A maximum gain of 134.97 and an input offset current of only 0.623 nA were acquired for the on-chip signal processing circuit. By functionalizing the measurement microcantilevers with a biotin-avidin system method, human IgG, abrin, and staphylococcus enterotoxin B (SEB) were detected at a limit of detection (LOD) of 48 pg/mL. Moreover, multichannel detection of the three integrated microcantilever aptasensors was also verified by detecting SEB. All these experimental results indicate that the design and process of monolithically integrated microcantilevers can meet the requirements of high-sensitivity detection of biomolecules.

High-power and reliable GaN-based vertical light-emitting diodes on 4-inch silicon substrate.

High-power and reliable GaN-based vertical light-emitting diodes (V-LEDs) on 4-inch silicon substrate were fabricated and characterized in this article. The metallization scheme reliability was improved by depositing the Pt/Ti films that surround the compressed Ag/TiW films to protect it from environmental humidity. We demonstrated that although current crowding in V-LEDs was not as severe as that in lateral light-emitting diodes (L-LEDs), high current density around the opaque metal n-electrode in V-LEDs remained a problem. A SiO2 current blocking layer (CBL) was incorporated in V-LEDs to modify the current distribution. Roughening the emitting surface of V-LEDs with KOH and H3PO4 etchant was compared and the influence of surface roughening on the emission property of V-LEDs was studied. The high-power V-LEDs showed low forward voltage with small series resistance and high light output power (LOP) without saturation up to 1300 mA. Under 350 mA injection current, V-LEDs achieved an excellent light output power (LOP) of 501 mW with the peak emission wavelength at 453 nm. The prominent output performance of V-LEDs demonstrated in this work confirmed that integrating the optimized metallization scheme, SiO2 CBL and surface texturing by KOH wet etching is an effective approach to higher performance V-LEDs.

High-Power GaN-Based Vertical Light-Emitting Diodes on 4-Inch Silicon Substrate.

We demonstrate high-power GaN-based vertical light-emitting diodes (LEDs) (VLEDs) on a 4-inch silicon substrate and flip-chip LEDs on a sapphire substrate. The GaN-based VLEDs were transferred onto the silicon substrate by using the Au-In eutectic bonding technique in combination with the laser lift-off (LLO) process. The silicon substrate with high thermal conductivity can provide a satisfactory path for heat dissipation of VLEDs. The nitrogen polar n-GaN surface was textured by KOH solution, which not only improved light extract efficiency (LEE) but also broke down Fabry-Pérot interference in VLEDs. As a result, a near Lambertian emission pattern was obtained in a VLED. To improve current spreading, the ring-shaped n-electrode was uniformly distributed over the entire VLED. Our combined numerical and experimental results revealed that the VLED exhibited superior heat dissipation and current spreading performance over a flip-chip LED (FCLED). As a result, under 350 mA injection current, the forward voltage of the VLED was 0.36 V lower than that of the FCLED, while the light output power (LOP) of the VLED was 3.7% higher than that of the FCLED. The LOP of the FCLED saturated at 1280 mA, but the light output saturation did not appear in the VLED.

Improvement in Light Output of Ultraviolet Light-Emitting Diodes with Patterned Double-Layer ITO by Laser Direct Writing.

A patterned double-layer indium-tin oxide (ITO), including the first unpatterned ITO layer serving as current spreading and the second patterned ITO layer serving as light extracting, was applied to obtain uniform current spreading and high light extraction efficiency (LEE) of GaN-based ultraviolet (UV) light-emitting diodes (LEDs). Periodic pinhole patterns were formed on the second ITO layer by laser direct writing to increase the LEE of UV LED. Effects of interval of pinhole patterns on optical and electrical properties of UV LED with patterned double-layer ITO were studied by numerical simulations and experimental investigations. Due to scattering out of waveguided light trapped inside the GaN film, LEE of UV LED with patterned double-layer ITO was improved as compared to UV LED with planar double-layer ITO. As interval of pinhole patterns decreased, the light output power (LOP) of UV LED with patterned double-layer ITO increased. In addition, UV LED with patterned double-layer ITO exhibited a slight degradation of current spreading as compared to the UV LED with a planar double-layer ITO. The forward voltage of UV LED with patterned double-layer ITO increased as the interval of pinhole patterns decreased.