Thermal effect analysis on cuboid Pr:YLF crystals pumped by blue laser diodes.

Using blue laser diodes (LDs) to pump Pr:YLF crystals can directly realize visible-band laser output. Compared with the traditional frequency doubling and LD direct output method, it has the advantages of simple design, compact structure, and high beam quality. For solid-state lasers, pump-induced thermal effects of gain media are the principal limiting factors for the desired high-power output. In this paper, internal temperature space model distribution of a rectangular cross-section Pr:YLF crystal is established. On this basis, the temperature distribution, thermal stress distribution, and thermal focal length variation of single-end pumped and double-end pumped laser crystals are analyzed. The results are verified by COMSOL simulations and experimental measurements. To our knowledge, this analysis is the first to examine the thermal effect of a rectangular cross-section Pr:YLF crystal, analyzing the limit power that the crystal can withstand, which paves the way for better performances of visible lasers with stable and high-power output.

Rhodium-catalyzed C-H activation/annulation of amidines with 4-diazoisochroman-3-imines toward isochromeno[3,4-c]isoquinolines.

A rhodium-catalyzed C-H activation/annulation of amidines with 4-diazoisochroman-3-imines has been established to afford a series of 8-amino-5H-isochromeno[3,4-c]isoquinolines in moderate to good yields with good functional group tolerance. This reaction proceeded in a sequential C-H activation/carbene migration insertion/intramolecular annulation procedure and featured the construction of a C-C and C-N bond in one pot. UV-vis and fluorescence spectral analyses of these highly fused heteroarenes were performed.

Cobalt- or rhodium-catalyzed synthesis of 1,2-dihydrophosphete oxides via C-H activation and formal phosphoryl migration.

A highly stereo- and chemoselective intermolecular coupling of diverse heterocycles with dialkynylphosphine oxides has been realized via cobalt/rhodium-catalyzed C-H bond activation. This protocol provides an efficient synthetic entry to functionalized 1,2-dihydrophosphete oxides in excellent yields via the merger of C-H bond activation and formal 1,2-migration of the phosphoryl group. Compared with traditional methods of synthesis of 1,2-dihydrophosphetes that predominantly relied on stoichiometric metal reagents, this catalytic system features high efficiency, a relatively short reaction time, atom-economy, and operational simplicity. Photophysical properties of selected 1,2-dihydrophosphete oxides are also disclosed.

Up-regulation of circARF3 reduces blood-brain barrier damage in rat subarachnoid hemorrhage model via miR-31-5p/MyD88/NF-κB axis.

Inflammation events have been found to aggravate brain injury and blood-brain barrier (BBB) damage following subarachnoid hemorrhage (SAH). This study probed the role and mechanism of a novel circRNA, circARF3, in regulating the BBB injury in SAH rats and hypoxia-induced vascular endothelial cell (VEC) injury in vitro. Levels of circARF3 and miR-31-5p were monitored by RT-PCR. The expression of inflammatory factors IL-1ß and TNF-α was verified by ELISA. In vivo SAH model was constructed in Sprague Dawley (SD) rats. The BBB integrity and cerebral edema, as well as the neurological functions of the rats were evaluated. The apoptotic neurons and microglia in brain lesions were examined by immunohistochemistry (IHC). The MyD88/NF-κB pathway was tested by Western blot. Furthermore, gain-of functional assay were constructed to explore the effects of circARF3 and miR-31-5p in primary cultured brain microvascular endothelial cell (BMEC) injury and microglial inflammation induced by oxygen and glucose deprivation (OGD). circARF3 was significantly down-regulated in plasma and CSF in SAH patients with higher Fisher stages. In the SAH rat model, overexpressing circARF3 improved BBB integrity and neurological score, decreased neuronal apoptosis and microglial activation in ipsilateral basal cortex, with declined miR-31-5p expression and MyD88-NF-κB activation. In vitro, overexpressing circARF3 attenuated OGD-mediated integrity destruction of BMECs and microglial induced neuroinflammation, while overexpressing miR-31-5p had opposite effects. Mechanistically, circARF3 sponged miR-31-5p as an endogenous competitive RNA and dampens its expression, thus inactivating MyD88-NF-κB pathway. CircARF3 attenuates BBB destruction in SAH rats by regulating the miR-31-5p-activated MyD88-NF-κB pathway.

Multiple source frequency-modulated continuous-wave optical reflectometry: theory and experiment.

We propose and demonstrate a novel approach to increase the effective bandwidth of a frequency-modulated continuous-wave (FMCW) ranging system. This is achieved by algorithmically stitching together the swept spectra of separate laser sources. The result is an improvement in the range resolution proportional to the increase in the swept-frequency range. An analysis of this system as well as the outline of the stitching algorithm are presented. Using three distinct swept-frequency optical waveforms, we experimentally demonstrate a threefold improvement in the range resolution of a three-sweep approach over the conventional FMCW method.

Copper-Mediated Direct Cyanation of Heteroarene and Arene C-H Bonds by the Combination of Ammonium and DMF.

A copper-mediated cyanation of heteroarene and arene C-H bonds has been developed, where ammonium iodide and DMF served as a safe cyanating combination. This procedure shows a broad substrate scope, allowing the facile access of 2-cyano indole, 1-cyano carbazole, 2-cyano pyrrole, and 2-cyano 1-pyridinyl benzene in high yields with good functional group tolerance.

Insight into miRNAs related with glucometabolic disorder.

A microRNA (miRNA) is a single-stranded, small and non-coding RNA molecule that contains 20-25 nucleotides. More than 2000 miRNAs have been identified in human genes since the first miRNA was discovered in Caenorhabditis elegans in the early 1990s. miRNAs play a crucial role in various biological processes by regulating gene expression through post-transcriptional mechanisms. The alterations of their levels are associated with various diseases, such as glucometabolic disorder and lipid metabolism disorder. In recent years, miRNAs have been proved to be involved in regulating the functions of pancreatic ß-cells, insulin resistance and other biological behaviors related to glucometabolic disorder and the pathogenesis of diabetes mellitus (DM). This review summarized specific miRNAs, including miRNA-375 (miR-375), miRNA-155 (miR-155), miRNA-21 (miR-21), miRNA-33 (miR-33), the let-7 family and some other miRNAs related to glucometabolic regulation, introduced the obstacles and challenges in miRNA therapy, and discussed the prospect of new treatment methods for glucometabolic disorder.

Efficient isolation and high yield of epidermal cells from foreskin biopsies by dynamic trypsinization.

Cultured keratinocytes play important roles in burn wound healing and scientific research studies. We aimed to modify the isolation method to avoid over-digestion, maximize the number of isolated epidermal cells and establish a more efficient and innocuous way of cell isolation. Compared to the conventional method, the modified method combines the more dynamic process of enzymatic digestion with multiple harvestings of dissociated cells via digestion. The cells from each harvesting were immediately re-suspended in culture medium with serum to avoid extended trypsinization and then pooled for further analysis. The number of viable cells isolated per gram of adult foreskin epidermis was (18.88±13.22)×106 cells in the control group and (67.34±30.66)×106 cells in the modified group (p<0.001). No significant differences were observed in the proportion of CD49f-positive cells between the two groups (p>0.05). The modified method was significantly more efficient in dissociating keratinocytes from each unit of skin biopsy, which is particularly important for treating severe burns when donor skin is limited.

Raman amplification of 40 Gb/s data in low-loss silicon waveguides.

We demonstrate on-chip Raman amplification of an optical data signal at 40 Gb/s in a silicon-on-insulator p-i-n rib waveguide. Using 230 mW of coupled pump power, on/off gain of up to 2.3 dB is observed, while signal integrity is maintained. In addition, the gain is measured as a function of signal wavelength detuning from the Stokes wavelength. The Lorentzian linewidth of the Raman gain profile is determined to be approximately 80 GHz. This provides applicability for the selective amplification of individual DWDM optical channels.

Monolithic integrated Raman silicon laser.

We present a monolithic integrated Raman silicon laser based on silicon-on-insulator (SOI) rib waveguide race-track ring resonator with an integrated p-i-n diode structure. Under reverse biasing, we achieved stable, single mode, continuous-wave (CW) lasing with output power exceeding 30mW and 10% slope efficiency. The laser emission has high spectral purity with a measured side mode suppression exceeding 70dB and laser linewidth of <100 kHz. This laser architecture allows for on-chip integration with other silicon photonics components to provide a highly integrated and scaleable monolithic device.

Demonstration of wavelength conversion at 40 Gb/s data rate in silicon waveguides.

We report an efficient wavelength conversion via four-wave-mixing in reverse biased silicon-on-isolator p-i-n rib waveguides and demonstrate, for the first time, the conversion of a high-speed optical pseudo-random bit sequence data at 40 Gb/s. Results give a wavelength conversion efficiency of -8.6dB using a 8cm long waveguide with clear open eye on the wavelength converted signal . Conversion efficiency as functions of pump power and bias voltages has also been investigated. We show a slope efficiency close to 2 as predicted by theory.

Controlling nonlinear processes in microstructured fibers using shaped pulses.

It is possible to modify pulse propagation and nonlinear interactions in microstructured fibers using phase-tailored ultrashort laser pulses. We experimentally investigate how pre-shaping of the input laser pulse can be used to alter its evolution and subsequent output characteristics. We also demonstrate how adaptive pulse shaping can be used to control the output properties of the pulse spectrum. Numerical simulations based on the nonlinear Schrodinger equation predict the output spectral profiles of the propagated pulse in good agreement with experimental results, and elucidate the relevant processes producing the optimal output.

Multichannel dispersion compensation using a silicon waveguide-based optical phase conjugator.

We experimentally demonstrate dispersion compensation using a silicon-based optical phase conjugator. We achieve simultaneous transmission of four dense wavelength division multiplexing (DWDM) channels spaced at 100 GHz and operating at 10 Gbits/s over 320 km of standard fiber. The measured power penalty at bit error rate of 10(-9) is less than 0.3 dB.