A variable (0.2 to 5 MHz) repetition rate femtosecond laser was applied to delineate the role of thermal diffusion and heat accumulation effects in forming low-loss optical waveguides in borosilicate glass across a broad range of laser exposure conditions. For the first time, a smooth transition from diffusion-only transport at 200 kHz repetition rate to strong heat accumulation effects at 0.5 to 2 MHz was observed and shown to drive significant variations in waveguide morphology, with rapidly increasing waveguide diameter that accurately followed a simple thermal diffusion model over all exposure variables tested. Amongst these strong thermal trends, a common exposure window of 200 mW average power and approximately 15-mm/s scan speed was discovered across the range of 200 kHz to 2 MHz repetition rates for minimizing insertion loss despite a 10-fold drop in laser pulse energy. Waveguide morphology and thermal modeling indicate that strong thermal diffusion effects at 200 kHz give way to a weak heat accumulation effect at approximately 1 microJ pulse energy for generating low loss waveguides, while stronger heat accumulation effects above 1-MHz repetition rate offered overall superior guiding. A comprehensive characterization of waveguide properties is presented for laser writing in the thermal diffusion and heat accumulation regimes. The waveguides are shown to be thermally stable up to 800 degrees C and can be written in a convenient 520 microm depth range with low spherical aberration.

HighlightShort-term chilling in autumn activates the accumulation of CBF, which directly promotes DAM expression. DAMs subsequently inhibit FT2 expression to induce endo-dormancy; miR6390 might degrade DAM genes to release endo-dormancy.

A material architecture and laser-based microfabrication technique is introduced to produce electrically conductive films (sheet resistance = 2.95 Ω sq ; resistivity = 1.77 × 10 Ω m) that are soft, elastic (strain limit >100%), and optically transparent. The films are composed of a grid-like array of visually imperceptible liquid-metal (LM) lines on a clear elastomer. Unlike previous efforts in transparent LM circuitry, the current approach enables fully imperceptible electronics that have not only high optical transmittance (>85% at 550 nm) but are also invisible under typical lighting conditions and reading distances. This unique combination of properties is enabled with a laser writing technique that results in LM grid patterns with a line width and pitch as small as 4.5 and 100 µm, respectively-yielding grid-like wiring that has adequate conductivity for digital functionality but is also well below the threshold for visual perception. The electrical, mechanical, electromechanical, and optomechanical properties of the films are characterized and it is found that high conductivity and transparency are preserved at tensile strains of ≈100%. To demonstrate their effectiveness for emerging applications in transparent displays and sensing electronics, the material architecture is incorporated into a couple of illustrative use cases related to chemical hazard warning.

Bud dormancy is indispensable for the survival of perennial plants in cold winters.Abscisic acid (ABA) has essential functions influencing the endo-dormancy status. Dormancy-associated MADS-box/SHORT VEGETATIVE PHASE-like genes function downstream of the ABA signalling pathway to regulate bud dormancy. However, the regulation of DAM/SVP expression remains largely uncharacterized. In this study, we confirmed that endo-dormancy maintenance and PpyDAM3 expression are controlled by the ABA content in pear (Pyrus pyrifolia) buds. The expression of pear ABRE-BINDING FACTOR3 (PpyABF3) was positively correlated with PpyDAM3 expression. Furthermore, PpyABF3 directly bound to the second ABRE in the PpyDAM3 promoter to activate its expression. Interestingly, both PpyABF3 and PpyDAM3 repressed the cell division and growth of transgenic pear calli. Another ABA-induced ABF protein, PpyABF2, physically interacted with PpyABF3 and disrupted the activation of the PpyDAM3 promoter by PpyABF3, indicating DAM expression was precisely controlled. Additionally, our results suggested that the differences in the PpyDAM3 promoter in two pear cultivars might be responsible for the diversity in the chilling requirements. In summary, our data clarify the finely tuned regulatory mechanism underlying the effect of ABA on DAM gene expression and provide new insights into ABA-related bud dormancy regulation. K E Y W O R D S ABF3, Abscisic acid, bud dormancy, DAM, pear

Dormancy is an adaptive mechanism that allows temperate deciduous plants to survive unfavorable winter conditions. In the present work, we investigated the possible function of abscisic acid (ABA) on the endodormancy process in pear. The ABA content increased during pear flower bud endodormancy establishment and decreased towards endodormancy release. In total, 39 putative genes related to ABA metabolism and signal transductions were identified from pear genome. During the para- to endodormancy transition, PpNCED-2 and PpNCED-3 had high expression levels, while PpCYP707As expression levels were low. However, during endodormancy, the expression of PpCYP707A-3 sharply increased with increasing cold accumulation. At the same time, the ABA content of pear buds declined, and the percentage of bud breaks rapidly increased. On the other hand, the expression levels of PpPYLs, PpPP2Cs, PpSnRK2s, and PpABI4/ABI5s were also changed during the pear flower bud dormancy cycle. Furthermore, exogenous ABA application to para-dormant buds significantly reduced the bud breaks and accelerated the transition to endodormancy. During the whole treatment time, the expression level of PpPP2C-12 decreased to a greater extent in ABA-treated buds than in control. However, the expression levels of PpSnRK2-1, PpSnRK2-4, and PpABI5-1 were higher in ABA-treated buds. Our results indicated that PpCYP707A-3 and PpNCEDs play pivotal roles on the regulation of endodormancy release, while ABA signal transduction pathway also appears to be involved in the process. The present work provided the basic information about the function of ABA-related genes during pear flower bud dormancy process.

Performing single-cell electrophoresis separations using multiple parallel microchannels offers the possibility of both increasing throughput and eliminating cross-contamination between different separations. The instrumentation for such a system requires spatial and temporal control of both single-cell selection and lysis. To address these problems, a compact platform is presented for single-cell capillary electrophoresis in parallel microchannels that combines optical tweezers for cell selection and electromechanical lysis. Calcein-labeled acute myloid leukemia (AML) cells were selected from an on-chip reservoir and transported by optical tweezers to one of four parallel microfluidic channels. Each channel entrance was manufactured by F2-laser ablation to form a 20- to 10-microm tapered lysis reservoir, creating an injector geometry effective in confining the cellular contents during mechanical shearing of the cell at the 10-microm capillary entrance. The contents of individual cells were simultaneously injected into parallel channels resulting in electrophoretic separation as recorded by laser-induced fluorescence of the labeled cellular contents.

MicroRNA156 is an evolutionarily highly conserved plant micro-RNA (miRNA) that controls an age-dependent flowering pathway. miR156 and its target SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes regulate anthocyanin accumulation in plants, but it is unknown whether this process is affected by light. Red Chinese sand pear (Pyrus pyrifolia) fruits exhibit a unique coloration pattern in response to bagging treatments, which makes them appropriate for studying the molecular mechanism underlying light-induced anthocyanin accumulation in fruit. Based on high-throughput miRNA and degradome sequencing data, we determined that miR156 was expressed in pear fruit peels, and targeted four SPL genes. Light-responsive elements were detected in the promoter regions of the miR156a and miR156ba precursors. We identified 19 SPL genes using the “Suli” pear (Pyrus pyrifolia Chinese White Pear Group) genome database, of which seven members were putative miR156 targets. The upregulated expression of anthocyanin biosynthetic and regulatory genes and downregulated expression of PpSPL2, PpSPL5, PpSPL7, PpSPL9, PpSPL10, PpSPL13, PpSPL16, PpSPL17, and PpSPL18 were observed in pear fruits after bags were removed from plants during the anthocyanin accumulation period. Additionally, miR156a/ba/g/s/sa abundance increased after bags were removed. Yeast two-hybrid results suggested that PpMYB10, PpbHLH, and PpWD40 could form a protein complex, probably involved in anthocyanin biosynthesis. Additionally, PpSPL10 and PpSPL13 interacted with PpMYB10. The results obtained in this study are helpful in understanding the possible role of miR156 and its target PpSPL genes in regulating light-induced red peel coloration and anthocyanin accumulation in pear.

The confinement of laser interactions inside transparent materials assisted by tight optical focusing and short-pulsed nonlinear interactions has driven many high-resolution patterning and probing applications in science and technology. In thin transparent films, laser interactions confined to the film/substrate interface have underpinned blistering and ejection processes for nanofluidic channel fabrication, film patterning and cell catapulting. Here, we harness femtosecond lasers to drive nonlinear interactions within Fabry-Perot interference fringes to define narrow nanolength scale zones for highly resolved internal structuring of a film of refractive index, n film , at fringe maxima separated by l/2n film . This novel interaction internally cleaves the film to open subwavelength internal cavities and form thin membranes at single or multiple depths from which follow significant opportunities for writing multilevel nanofluidic channels inside the film, as well as ejecting nanodisks at quantized film depths for coloring and three-dimensional surface patterning that promise new compact types of lab-in-film devices.