Fabrication of three-dimensional microdisk resonators in calcium fluoride by femtosecond laser micromachining

We report on fabrication of on-chip calcium fluoride (CaF2) microdisk resonators using water-assisted femtosecond laser micromachining. Focused ion beam (FIB) milling is used to create ultra-smooth sidewalls. The quality (Q)-factors of the fabricated microresonators are measured to be 4.2x10^4 at wavelengths near 1550 nm. The Q factor is mainly limited by the scattering from the bottom surface of the disk whose roughness remains high due to the femtosecond laser micromachining process. This technique facilitates formation of on-chip microresonators on various kinds of bulk crystalline materials, which can benefit a wide range of applications such as nonlinear optics, quantum optics, and chip-level integration of photonic devices.Comment: 7 pages, 3 figure

On-chip tuning of the resonant wavelength in a high-Q microresonator integrated with a microheater

We report on fabrication of a microtoroid resonator of high-quality (high-Q) factor integrated with an on-chip microheater. Both the microresonator and microheater are fabricated using femtosecond laser three-dimensional (3D) micromachining. The microheater, which is located about 200 micron away from the microresonator, has a footprint size of 200 micron by 400 micron. Tuning of the resonant wavelength in the microresonator has been achieved by varying the voltage applied on the microheater. The drifting of the resonant wavelength shows a linear dependence on the square of the voltage applied on the microheater. We found that the response time of the microresonator is less than 10 secs which is significantly shorter than the time required for reaching a thermal equilibrium on conventional heating instruments such as an external electric heater

Fabrication of an integrated high-quality-factor (high-Q) optofluidic sensor by femtosecond laser micromachining

We report on fabrication of a microtoroid resonator of a high-quality factor (i. e., Q-factor of ~3.24x10^6 measured under the critical coupling condition) integrated in a microfluidic channel using femtosecond laser three-dimensional (3D) micromachining. Coupling of light into and out of the microresonator has been realized with a fiber taper that is reliably assembled with the microtoroid. The assembly of the fiber to the microtoroid is achieved by welding the fiber taper onto the sidewall of the microtoroid using CO_2 laser irradiation. The integrated microresonator maintains a high Q-factor of 3.21x10^5 as measured in air, which should still be sufficient for many sensing applications. We test the functionality of the integrated optofluidic sensor by performing bulk refractive index sensing of purified water doped with tiny amount of salt. It is shown that a detection limit of ~1.2x10^-4 refractive index unit can be achieved. Our result showcases the capability of integration of high-Q microresonators with complex microfluidic systems using femtosecond laser 3D micromachining.Comment: 6 pages, 5 figures. arXiv admin note: text overlap with arXiv:1402.135

Agrimol B inhibits colon carcinoma progression by blocking mitochondrial function through the PGC-1α/NRF1/TFAM signaling pathway

BackgroundThe activation of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) stimulates the transcription of the downstream target proteins, mitochondrial transcription factor A (TFAM) and nuclear respiratory factor 1 (NRF1), which induces mitochondrial biogenesis and promotes colorectal tumorigenesis. Agrimol B (Agr) is a constituent of Agrimonia pilosa Ledeb. that exerts anticancer effects. Herein, we aimed to investigate the antitumor activity of Agr and its mechanism of action.MethodsThe interaction between Agr and PGC-1α was predicted by molecular docking. After the treatment with different concentrations of Agr (0, 144, 288, and 576 nM), the cell viability, migration rate, proliferation rate, and apoptosis rate of human colon cancer HCT116 cells were determined. Mitochondrial activity, cellular reactive oxygen species (ROS), and mitochondrial membrane potential were assessed to measure the regulatory effect of Agr on mitochondrial function. Western blotting (WB) assay was used to examine the expression of PGC-1α, NRF1, and TFAM, as well as of the pro-apoptotic proteins, Bax and Caspase-3, and the antiapoptotic protein (Bcl-2). Finally, subcutaneous tumor xenograft model mice were used to evaluate the effect of Agr on colorectal cancer (CRC) in vivo.ResultsThe molecular docking results revealed a high likelihood of Agr interacting with PGC-1α. Agr inhibited the proliferation and migration of HCT116 cells, promoted ROS production and mitochondrial oxidative stress, inhibited mitochondrial activity, and decreased mitochondrial membrane potential. Agr induced cell apoptosis and, in combination with PGC-1α, impaired mitochondrial biogenesis and suppressed the expression of NRF1 and TFAM. Agr also suppressed the expression of Bcl-2 and Cleaved-Caspase-3 and increased the expression of Bax and Caspase-3. In addition, the in vivo antitumor effect and mechanism of Agr were confirmed by using a subcutaneous tumor xenograft mouse model.ConclusionsOur findings demonstrated that Agr regulates the expression of PGC-1α, thereby inducing mitochondrial dysfunction and promoting tumor cell apoptosis. This work highlights the potential of Agr as a promising therapeutic candidate in CRC

Fluorescence Microscopy with Tailored Illumination Light

Fluorescence microscopy has long been a valuable tool for biological and medical imaging. Control of optical parameters such as the amplitude, phase, polarization and propagation angle of light gives fluorescence imaging great capabilities ranging from single molecule imaging to long-term observation of living organisms. While numerous fluorescence imaging techniques have been developed over the past decades, there is always an inevitable tradeoff among the spatial resolution, imaging speed, contrast, photodamage and the total cost when it comes to choose the appropriate microscope. A main goal of my dissertation research is to develop state-of-the-art microscope systems that exhibit unprecedented performance in single-molecule fluorescence imaging and live-cell imaging for broader biomedical applications by tailoring the optical illumination beams. In details, I have designed and prototyped: 1) a highly inclined swept illumination for wide-field fluorescence microscope, which greatly improves the sectioning capability with a large field of view and ultrasensitivity; 2) dual inclined line-scan confocal microscope, which reduces photodamage while maintaining the background rejection capability compared to conventional line-scan confocal microscope; 3) a static non-diffracting light-sheet generation by controlling the spatial coherence of light emitting diodes and laser

Extended Field-Of-View Single-Molecule Imaging By Highly Inclined Swept Illumination

Single-molecule imaging inside cells is a valuable tool to study subcellular structures, gene expression, and the dynamics of biomolecules. Here, we present highly inclined swept tile illumination microscopy. By sweeping a thin highly inclined and laminated optical sheet (HILO) with confocal slit detection, our method provides a twofold thinner illumination and greater than fortyfold larger imaging area than conventional HILO microscopy, enabling 3D single-molecule imaging with a high signal-to-background ratio. We demonstrate single-molecule mRNA imaging with a few probes or a single probe in cultured cells and mouse brain tissues, and video-rate live-cell imaging

The impact of antimicrobial management by clinical pharmacists in obstetrics and gynecology on antimicrobial indicators, bacterial resistance and drug costs from 2011 to 2021 in China

Objectives: The goal of our study is to analyze the effectiveness and role of clinical pharmacists in antibiotic management through retrospective research from 2011 to 2021, depending on the current scenario of the antibiotic application in China. Methods: We formed a team of pharmacists to carry out multifaceted intervention measures, such as forming a working group, developing a plan, establishing management rules via the pre-trial system, prescription comments, collaborating with the administrative department, implementing training and publicity, and so on. Antibiotic use was studied, bacterial drug resistance was determined, and antibiotic costs were computed. Results: The pharmacist intervention and rectification of inappropriate antibacterial drug orders considerably enhanced the rational use rate of antibiotics and reduced the cost of antibiotics. Antibiotic use in clean surgery decreased from 90.22% to 11.14%, the use rate of antibiotics decreased from 63.82% to 30.26%, and antibiotic use intensity decreased from 42.75DDDs to 30.04DDDs. The types, timing, and course of antibacterials used in wards were all improved to varying degrees. Bacterial drug resistance improved noticeably, with resistance of Escherichia coli to cephalosporins, ciprofloxacin and carbapenems decreased in varying degrees. The use of antibacterial drugs has decreased significantly. Conclusions: It is feasible and effective for pharmacists in gynecology and obstetrics to control antibiotic use, which plays a positive role in promoting the safe, effective, and cost-effective use of antibiotics and serves as a valuable reference for the antibiotic management

Survey on NLOS Identification and Error Mitigation for UWB Indoor Positioning

Ultra-wideband (UWB) positioning systems often operate in a non-line-of-sight (NLOS) environment. NLOS propagation has become the main source of ultra-wideband indoor positioning errors. As such, how to identify and correct NLOS errors has become a key problem that must be solved in high-accuracy indoor positioning technology. This paper firstly describes the influence of the NLOS propagation path on localization accuracy and the generation method of ultra-wideband signals, and secondly classifies and analyzes the currently available algorithms for ultra-wideband non-line-of-sight (NLOS) identification and error suppression. For the identification of NLOS, the residual analysis judgement method, statistical feature class identification method, machine learning method and geometric feature judgement method are discussed. For the suppression of NLOS propagation errors, weighting-based methods, filtering-based methods, line-of-sight reconstruction algorithms, neural network algorithms, optimization methods with constraints, and path tracing methods are discussed. Finally, we conclude the paper and point out the problems that need to be solved in NLOS indoor positioning