Ultra-high Q alumina optical microresonators in the UV and blue bands.

UV and visible photonics enable applications ranging from spectroscopic sensing to communication and quantum information processing. Photonics structures in these wavelength regimes, however, tend to experience higher loss than their IR counterpart. Particularly in the near-UV band, on-chip optical microresonators have not yet achieved a quality factor beyond 1 million. Here, we report ultra-low-loss photonic waveguides and resonators patterned from alumina thin films prepared by a highly scalable atomic layer deposition process. We demonstrate ultra high Q factor of 1.5×106 at 390 nm, a record value at UV bands, and 1.9×106 at 488.5 nm.

Establishment of Functional PCR-Based Markers against Bacterial Leaf Blight Disease in Rice Landraces of Yunnan Province of China.

Bacterial leaf blight is a devastating disease of rice worldwide. The resistant genes are routinely transferred from landraces to cultivated varieties through backcross breeding along with marker-assisted selection. In the present study, we use the gene-specific markers to screen the rice landraces in Yunnan Province of China. We collected 404 representative samples of 24 different rice landraces from Yunnan Province of China. The initial PCR-based screening suggested that the leaf blight resistance was not evenly distributed in Yunnan Province. Our results indicate that there is a complete loss of resistance for landraces based on xa5 and xa13 genes. On the other hand, landraces harboring Xa7 and Xa21 showed a high level of resistance. Using gene-specific PCR-based data, we were able to identify the resistant, susceptible and heterozygous populations across Yunnan Province. The widely used Xa21 gene alone showed a remarkable level of resistance throughout the province, indicating its potential to develop broad-spectrum resistance in rice germplasm. The key aspects of bacterial blight spread according to local sites in Yunnan Province and the resistance conferred by different landraces due to the presence of different resistance genes are discussed.

Photocatalytic CO2 Reduction with Dissolved Carbonates and Near-Zero CO2(aq) by Employing Long-Range Proton Transport.

Photocatalytic CO2 reduction (CO2R) in ∼0 mM CO2(aq) concentration is challenging but is relevant for capturing CO2 and achieving a circular carbon economy. Despite recent advances, the interplay between the CO2 catalytic reduction and the oxidative redox processes that are arranged on photocatalyst surfaces with nanometer-scale distances is less studied. Specifically, mechanistic investigation on interdependent processes, including CO2 adsorption, charge separation, long-range chemical transport (∼100 nm distance), and bicarbonate buffer speciation, involved in photocatalysis is urgently needed. Photocatalytic CO2R in ∼0 mM CO2(aq), which has important applications in integrated carbon capture and utilization (CCU), has rarely been studied. Using 0.1 M KHCO3 (aq) of pH 7 but without continuously bubbling CO2, we achieved ∼0.1% solar-to-fuel conversion efficiency for CO production using Ag@CrOx nanoparticles that are supported on a coating-protected GaInP2 photocatalytic panel. CO is produced at ∼100% selectivity with no detectable H2, even with copious protons co-generated nearby. CO2 flux to the Ag@CrOx CO2R sites enhances CO2 adsorption, probed by in situ Raman spectroscopy. CO is produced with local protonation of dissolved inorganic carbon species in a pH as high as 11.5 when using fast electron donors such as ethanol. Isotopic labeling using KH13CO3 was used to confirm the origin of CO from the bicarbonate solution. We then employed COMSOL Multiphysics modeling to simulate the spatial and temporal pH variation and the local concentrations of bicarbonates and CO2(aq). We found that light-driven CO2R and CO2 reactive transport are mutually dependent, which is important for further understanding and manipulating CO2R activity and selectivity. This study enables direct bicarbonate utilization as the source of CO2, thereby achieving CO2 capture and conversion without purifying and feeding gaseous CO2.

Novel Variation and Evolution of AvrPiz-t of Magnaporthe oryzae in Field Isolates.

The product of the avirulence (Avr) gene of Magnaporthe oryzae can be detected by the product of the corresponding resistance (R) gene of rice and activates immunity to rice mediated by the R gene. The high degree of variability of M. oryzae isolates in pathogenicity makes the control of rice blast difficult. That resistance of the R gene in rice has been lost has been ascribed to the instability of the Avr gene in M. oryzae. Further study on the variation of the Avr genes in M. oryze field isolates may yield valuable information on the durable and effective deployment of R genes in rice production areas. AvrPiz-t and Piz-t are a pair of valuable genes in the Rice-Magnaporthe pathosystem. AvrPiz-t is detectable by Piz-t and determines the effectiveness of Piz-t. To effectively deploy the R gene Piz-t, the distribution, variation, and evolution of the corresponding Avr gene AvrPiz-t were found among 312 M. oryzae isolates collected from Yunnan rice production areas of China. PCR amplification and pathogenicity assays of AvrPiz-t showed that 202 isolates (64.7%) held AvrPiz-t alleles and were avirulent to IRBLzt-T (holding Piz-t). There were 42.3-83.3% avirulent isolates containing AvrPiz-t among seven regions in Yunnan Province. Meanwhile, 11 haplotypes of AvrPiz-t encoding three novel AvrPiz-t variants were identified among 100 isolates. A 198 bps insertion homologous to solo-LTR of the retrotransposon inago2 in the promoter region of AvrPiz-t in one isolate and a frameshift mutation of CDS in another isolate were identified among 100 isolates, and those two isolates had evolved to virulent from avirulent. Synonymous mutation and non-AUG-initiated N-terminal extensions keeps the AvrPiz-t gene avirulence function in M. oryzae field isolates in Yunnan. A haplotype network showed that H3 was an ancestral haplotype. Structure variance for absence (28.2%) or partial fragment loss (71.8%) of AvrPiz-t was found among 39 virulent isolates and may cause the AvrPiz-t avirulence function to be lost. Overall, AvrPiz-t evolved to virulent from avirulent forms via point mutation, retrotransposon, shift mutation, and structure variance under field conditions.