1.3um Lasers Using Nd3+ Doped Apatite Crystals

Laser pumping and flashlamp pumping of apatite crystals such as trivalent neodymium-doped strontium fluorapatite (Sr.sub.5 (PO.sub.4).sub.3 F) emits efficient lasing at both 1.059 and 1.328 .mu.m. The pump sources for the SFAP material doped with Nd.sup.3+ includes pulsed Cr:LiSrAlF.sub.6 tuned to approximately 805.4 nm. Alternatively, similar results occurred using a continuous wave laser source of Ti:sapphire tuned to approximately 805.4 nm. A preferred embodiment includes a resonant cavity with a high reflectivity mirror having a reflectivity of 100% and an output coupler mirror with a reflectivity of less than 100%. An optional tuning component such as a Pockels Cell-Polarizer combination can also be included. The SFAP material doped with Nd.sup.3+ exhibits a large absorption cross section, high emission cross section, and long radiative lifetime

Proteome analysis for antifungal effects of Bacillus subtilis KB-1122 on Magnaporthe grisea P131.

Rice blast, caused by Magnaporthe grisea threatens rice production worldwide. It is important to develop novel and environment-safe strategies to control the fungus. Here we reported that Bacillus subtilis KB-1122 could strikingly inhibit the growth of M. grisea P131 in agar diffusion assays. To further understand the molecular mechanism on the suppressive role of B. subtilis on M. grisea, the antagonist-pathogen interaction of the two strains was studied by using comparative proteome analysis in this report. The cellular and culture supernatant (CSN) proteins were prepared from co-culture and subjected to two-dimensional polyacrylamide gel electrophoresis. Proteome analysis revealed 33 cellular and 18 CSN proteins showing changes upon co-culture respectively. Importantly, down-regulated cellular proteins came from M. grisea, whereas up-regulated proteins derived from B. subtilis. Results suggested that glyceraldehyde-3-phosphate dehydrogenase and serine protein kinase might contribute to antifungal activity of B. subtilis KB-1122. Of CSN proteins identified, the endo-1,4-beta-glucanase (involved in degradation of polysaccharides) was up-regulated consistently at different times of incubation. This suggests that this enzyme plays an important role in the interaction between B. subtilis KB-1122 with M. grisea P131

Butterfly‐like Tetraazaacenequinodimethane Derivatives: Synthesis, Structure and Halochromic Properties

Two novel molecules TAP and TAH with pronounced reversible halochromic properties have been synthesized and fully characterized. Their butterfly-like structures have been confirmed through single-crystal X-ray diffraction. Their UV-Vis absorption after protonation dramatically red-shifted with naked-eye-visible color change in a very dilute concentration of 10-5 M. Note that the original color of the solution can be recovered after the neutralization with a base.Ministry of Education (MOE)Q.Z. acknowledges financial support from AcRF Tier 1 (RG 111/17,RG 2/17, RG 114/16,RG 113/18)and Tier 2 (MOE2017-T2-1-021and MOE 2018-T2-1-070),Singapore.X.L. thank the support from the National Natural Science Foundation of China(21676188) and the Science and Technology Plan Project of Tianjin(19ZXNCGX00020).J.Z. acknowledges financial support from Na-tional Natural Science Foundation of China, Grant Nos. 21773016.QZ also thanks the support from State Key Laboratory of Supramolecular Structure and Materials, Jilin University (sklssm2020041

Synthesis and rheological performance of shear-thickening waterborne polyurethane

Shear-thickening fluids (STFs) are a new type of intelligent material with excellent performance whose viscosity increase sharply with the increase of shear rate or shear stress. However, the synthesis yield of dispersed phase particles is low, and the particle re-dispersion process is challenging for the industrial production of STFs. In this work, through structural design, a waterborne polyurethane (WPU) with typical shear-thickening properties was synthesized for the first time. This synthesis process is conducive to industrial production. The rheological properties of the synthesized WPU at different concentrations, temperatures, and pH were studied using a rheometer. The results showed that the WPU exhibited typical shear-thickening behavior. However, due to the special core–shell structure of the WPU particles, the shear rate has two transition responses to the shear-thickening behavior. With increasing concentration, the shear-thickening performance of the WPU is enhanced, and the critical shear rate is decreased. For the coexistence of Brownian motion and solvation, the rheological curve of the WPU exhibits a complex response to temperature increase; its shear-thickening behavior decreases with rising temperature, but the viscosity first decreases and then increases with temperature. Due to the presence of carboxyl groups on the surface of the WPU particles, its shear-thickening performance shows a strong response to pH. By appropriately adjusting the pH, the viscosity and particle size of the WPU can be increased through the ionization of carboxyl groups, thereby enhancing the shear-thickening behavior

Pyrene-containing twistarene : twelve benzene rings fused in a row

Success in obtaining higher-order twistarenes with precise structures is very important for fundamentally understanding the relationship between the structures and physical properties/optoelectronic applications. In this research, by using the advantages from a retro-Diels-Alder process (clean reaction) and the cross-conjugated nature of the pyrene unit, a novel dodeca-twistarene was prepared for the first time. Its structure, confirmed by single-crystal XRD analysis, indicates that it possesses a twisted angle (≈30°), and two neighboring molecules in the crystal lattice are perpendicular to each other because of the twisted character and the strong intermolecular CH-π interactions. However, its basic physicochemical properties suggest its instability in air derives from its elevated HOMO energy level, although NICS calculations confirm that the pyrene units contribution poorly to the π conjugation of the overall molecule.Ministry of Education (MOE)Accepted versionQ.Z acknowledges financial support from AcRF Tier 1 (RG 111/17, RG 2/17, RG 114/16, RG 8/16) and Tier 2 (MOE 2017- T2-1-021), Singapore. Dr. Liu acknowledges funding support from M4062018

Identification and Functional Analysis of LncRNAs in Response to Seed Aging in <i>Metasequoia glyptostroboides</i> by Third Generation Sequencing Technology

The seeds of Metasequia glyptostroboides Hu et Cheng, an endangered species, are susceptible to aging, making natural population renewal difficult and increasing the risk of extinction. LncRNAs play important roles in plant growth and development and biotic and abiotic stress responses, but the functions of lncRNAs in the aging process of M. glyptostroboides seeds are still unclear. In this study, we used single molecule real-time (SMRT) sequencing technology in combination with Illumina RNA-seq to analyze lncRNA changes during M. glyptostroboides seed aging. We identified 403 intergenic lncRNAs (lincRNAs), 29 intronic lncRNAs, and 25 antisense lncRNAs; screened 9000 differentially expressed mRNAs (DEGs) and 128 differentially expressed lncRNAs (DELs); and predicted 844 cis-target genes and 8098 trans-target genes. GO and KEGG functional annotation of target genes revealed that the regulation of the reactive oxygen species metabolic process, protein processing in the endoplasmic reticulum, and the MAPK signaling pathway and other pathways were significantly enriched, showing a high correlation with the mRNA enrichment results. In addition, we constructed a ceRNA network consisting of 18 lncRNAs, 38 miRNAs, and 69 mRNAs, in which some miRNAs and mRNAs related to seed aging were found. Among them, miR167(a,b,c,d) may compete with lncRNA_00185, which is related to plant aging, to regulate the expression of the RCD1(Radical-induced Cell Death1) gene, thus promoting the balance of seed reactive oxygen species and enhancing seed-aging resistance. These results will have significant reference value in elucidating the molecular mechanism of the seed aging of M. glyptostroboides sequoia, improving the storage capacity for crop seeds, and protecting rare germplasm resources

A 3D haloplumbate framework constructed from unprecedented Lindqvist-like highly coordinated [Pb6Br25]13- nanoclusters with temperature-dependent emission

Searching novel haloplumbate building units to construct three-dimensional (3D) frameworks is very important and highly desirable because such materials would possess new physical properties and potential applications. Here, by employing tetrakis(N-imidazolemethylene)methane(TIMM) as a structure-directing agent, the first 3D haloplumbate framework constructed from unprecedented Lindqvist-like highly coordinated [Pb6 Br25 ]13- nanoclusters has been successfully prepared under hydrothermal condition, where all Pb2+ centres in [Pb6 Br25 ]13- nanoclusters adopt seven-/eight-coordinated configurations. The as-obtained material is a wide-gap semiconductor (≈3.1 eV) and can be stable up to 320 °C. More importantly, this material has been demonstrated to show temperature-dependent emission. Our results could provide a new strategy to explore novel metal-halide open-framework materials.Ministry of Education (MOE)Accepted versionQ.Z acknowledges financial support from AcRF Tier 1 (RG 111/17, RG 2/17, RG 114/16, RG 8/16) and Tier 2 (MOE 2017-T2-1-021), Singapore. Q.X. gratefully acknowledges the funding support from Singapore Ministry of Education via AcRF Tier 1 grants (RG 113/16 and RG 194/17)

Synthesis, characterization and photophysical studies of a novel polycyclic diborane

Treatment of tetrakis(dimethylamino)diboron (B₂(NMe₂)₄) with 1,4-bis (2-(triisopropylsilyl)ethynyl)naphthalene-2,3-diamine (1) generated a large NBBN polycyclic compound 1,1-B₂{2,3-(NH)₂ -1,4-(ⁱPr₃ SiC₂)₂C₁₀H₄} (2). The X-ray structure analysis reveals that 2 has a twisted structure (dihedral angle ≈ 21.75°) with a rather short B-B bond (1.667(9) Å). Theoretical calculations on 1,1-B₂ isomer 2 and its counterpart 1,2-B₂ isomer 3 have been conducted to understand their frontier orbital energy levels. Compound 2 shows strong emission with a high quantum yield of 0.52, despite the presence of many unbeneficial non-radiative behaviors such as the vibration of the TIPS groups and the rotation of the B-B single bond

Two-dimensional and emission-tunable : an unusual perovskite constructed from lindqvist-type [Pb6Br19]7- nanoclusters

Preparing low-dimensional perovskite materials with novel building units is highly desirable because such materials have already been demonstrated to show unusual physical properties. In this report, we first reported a new and unusual two-dimensional perovskite framework, [B(HIm)4]4Pb13Br38 (1), constructed from novel Lindqvist-type [Pb6Br19]7- nanoclusters. The as-prepared material shows good water resistance and chemical/heat stability. More importantly, 1 has been proven to exhibit temperature/excitation-wavelength-dependent emission. A possible mechanism has been provided.MOE (Min. of Education, S’pore

Comprehensive Mitochondrial Metabolic Shift during the Critical Node of Seed Ageing in Rice

<div><p>The critical node (CN) in seed aging in rice (<i>Oryza sativa</i>) is the transformation from Phase I (P-I) to Phase II (P-II) of the reverse S-shaped curve (RS-SC). Although mitochondrial dysfunction plays a key role in seed ageing, the metabolic shift in the CN remains poorly understood. Here, we investigated the mitochondrial regulatory mechanisms during the CN of rice seed ageing. We showed that during the CN of seed ageing, the mitochondrial ultrastructure was impaired, causing oxygen consumption to decrease, along with cytochrome <i>c</i> (cyt <i>c</i>) oxidase and malate dehydrogenase (MDH) activity. In addition, the transcript levels for the alternative pathway of the electron transport chain (ETC) were significantly induced, whereas the transcripts of the cytochrome oxidase (COX) pathway were inhibited. These changes were concomitant with the down-regulation of mitochondrial protein levels related to carbon and nitrogen metabolism, ATP synthase (ATPase) complex, tricarboxylic acid cycle (TCA) cycle, mitochondrial oxidative enzymes, and a variety of other proteins. Therefore, while these responses inhibit the production of ATP and its intermediates, signals from mitochondria (such as the decrease of cyt <i>c</i> and accumulation of reactive oxygen species (ROS)) may also induce oxidative damage. These events provide considerable information about the mitochondrial metabolic shifts involved in the progression of seed ageing in the CN.</p></div