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The output of a wavelength-swept laser (WSL) based on a fiber Fabry–Pérot tunable filter (FFP-TF) tends to shift the peak wavelength due to external temperature or heat generated by the FFP-TF itself. Therefore, when measuring the output of WSL for a long time, it is very difficult to accurately measure a signal in the temporal domain corresponding to a specific wavelength of the output of the WSL. If the wavelength variation of the WSL output can be predicted through the peak time information of the forward scan or the backward scan from the WSL, the variation of the peak wavelength can be compensated for by adjusting the offset voltage applied to the FFP-TF. This study presents a successful stabilization method for peak wavelength variation in WSLs by adjusting the offset voltage of the FFP-TF with closed-loop control. The closed-loop control is implemented by measuring the deviation in the WSL peak position in the temporal domain using the trigger signal of the function generator. The feedback repetition rate for WSL stabilization was approximately 0.2 s, confirming that the WSL output and the peak position for the fiber Bragg grating (FBG) reflection spectrum were kept constant within ±7 μs at the maximum when the stabilization loop was applied. The standard deviations of WSL output and reflection peak positions were 1.52 μs and 1.59 μs, respectively. The temporal and spectral domains have a linear relationship; the ±7 μs maximum variation of the peak position corresponded to ±0.035 nm of the maximum wavelength variation in the spectral domain. The proposed WSL system can be used as a light source for temperature or strain-dependent sensors as it compensates for the WSL wavelength variation in applications that do not require a fast scanning rate.

Tauopathy is one of the major causes of neurodegenerative disorders and diseases such as Alzheimer’s disease (AD). Hyperphosphorylation of tau proteins by various kinases leads to the formation of PHF and NFT and eventually results in tauopathy and AD; similarly, neuroinflammation also exaggerates and accelerates neuropathy and neurodegeneration. Natural products with anti-tauopathy and anti-neuroinflammatory effects are highly recommended as safe and feasible ways of preventing and /or treating neurodegenerative diseases, including AD. In the present study, we isolated theasaponin E1 from ethanol extract of green tea seed and evaluated its therapeutic inhibitory effects on tau hyper-phosphorylation and neuroinflammation in neuroblastoma (SHY-5Y) and glioblastoma (HTB2) cells, respectively, to elucidate the mechanism of the inhibitory effects. The expression of tau-generating and phosphorylation-promoting genes under the effects of theasaponin E1 were determined and assessed by RT- PCR, ELISA, and western blotting. It was found that theasaponin E1 reduced hyperphosphorylation of tau and Aβ concentrations significantly, and dose-dependently, by suppressing the expression of GSK3 β, CDK5, CAMII, MAPK, EPOE4(E4), and PICALM, and enhanced the expression of PP1, PP2A, and TREM2. According to the ELISA and western blotting results, the levels of APP, Aβ, and p-tau were reduced by treatment with theasaponin E1. Moreover, theasaponin E1 reduced inflammation by suppressing the Nf-kB pathway and dose-dependently reducing the levels of inflammatory cytokines such as IL-1beta, IL-6, and TNF-alpha etc.

Rational weld seams sequence is important for improving welding productivity and quality. Hence, intelligent path optimization strategy is introduced to obtain optimized weld seams sequence in this article. The path length and total welding deformation are considered for multi-objective path planning. First, the optimization problem description is presented. At the same time, the path length and the total welding deformation of some sequences are calculated. Then, improved multi-objective particle swarm optimization algorithm is studied. In addition, the agent model is obtained based on the sample data and experiment design. At last, the proposed algorithm is applied to optimize the welding path length and total welding deformation. The simulation results show the effectiveness of the optimization strategy.

In this study, we develop an ultra-fast fiber Bragg grating sensor system that is based on the Fourier domain mode-locked (FDML) swept laser. A FDML wavelength swept laser has many advantages compared to the conventional wavelength swept laser source, such as high-speed interrogation, narrow spectral sensitivity, and high phase stability. The newly developed FDML wavelength swept laser shows a superior performance of a high scan rate of 31.3 kHz and a broad scan range of over 70 nm simultaneously. The performance of the grating sensor interrogating system using a FDML wavelength swept laser is characterized in both static and dynamic strain responses. (C) 2008 Optical Society of America

We present characteristics of a wavelength swept laser with a scanning fiber Fabry-Perot filter at 1300 nm. We investigate the dependence of the scanning frequencies in the swept laser. In conventional wavelength swept lasers, the relative intensity of the laser output decreases significantly as the scanning frequency increases. The peak wavelength of the output spectrum is red-shifted due to the nonlinear frequency downshifting in the semiconductor optical amplifier (SOA). In the Fourier domain mode-locked (FDML) wavelength swept laser, we investigate transient intensity profiles and the full width at half maximum in response to the injection currents and detuning of the scanning frequency. The degradation of the scanning range of the swept laser is caused by the deviation from the scanning frequency at 45.6 kHz. In addition, transient intensity profiles show significant asymmetric behavior in response to the detuned frequencies. Finally, the axial resolution and sensitivity as a function of imaging depth are analyzed for both forward and backward scans. With the FDML laser, the detection sensitivity up to 102 dB is achieved for the backward scans. The backward scans exhibit higher axial resolution and sensitivity than the forward scan. (C) 2008 Optical Society of America.

We report on the development of a high-speed, wide bandwidth Fourier domain mode-locked (FDML) wavelength swept laser of around 1300 nm using two gain media for high-resolution and high-speed Fourier domain optical coherence tomography. The wavelength swept laser is capable of FWHM scanning range of more than 135 nm at 45.6 kHz sweeping rate. The measured axial resolution of the forward scan is 6.6 mu m in air and 4.7 mu m in tissue. The peak power is 11.4 mW for both the forward and backward scans. The measured system sensitivity is achieved up to 100.7 dB. We also demonstrate OCT imaging using the FDML wavelength swept laser with two semiconductor optical amplifiers. (C) 2008 Optical Society of America.

Dental bases require low thermal conductivity and good mechanical properties, such as bonding with composite resins. This study aims to elucidate the physicochemical properties of premixed mineral trioxide aggregate (MTA) for its suitability as a dental base and to explore the optimal adhesive strategy with composite resin. The thermal conductivity and compressive strength of this premixed MTA are 0.12 W/(m•K) and 93.76 MPa, respectively, Which are deemed adequate for its application as dental base. When bonded to composite resin, the use of 37% phosphoric acid etching before applying the Clearfil SE bond significantly reduced the bonding strength between composite resin and premixed MTA. This was because the compressive strength and Vickers hardness of premixed MTA decreased, and tricalcium silicate was dissolved from the surface during acid etching. Therefore, it is recommended to avoid using 37% phosphoric acid etching when bonding premixed MTA and composite resin as a dental base. [ABSTRACT FROM AUTHOR]

Analysis of N-nitroso folic acid, a nitrosamine impurity found in folic acid, is challenging due to the complex sample matrices. Many of such supplements contain not only a variety of vitamins, including vitamin A, Bs, C, D and E, but also other ingredients such as minerals, docosahexaenoic acid (DHA), glucose syrup, sugar, and herbs. On the other hand, the strength of folic acid is typically low, ranging from 50 µg to 5 mg per unit. In this study, a highly selective and sensitive LC-MS/MS method was developed to accurately quantify N-nitroso folic acid in supplements containing folic acid. The sample was extracted by 0.1% ammonia solution: MeOH (9:1, v/v) containing 5 ng/mL of N-nitroso folic acid-d4 (Isotope internal standard). The quantification was performed by MRM in negative ionization mode. Mobile phases A and B were 0.1% formic acid in deionized water and methanol, respectively. The method was validated and found to have sufficient linearity (R2 > 0.995), accuracy (recovery 83–110%), precision (RSD 3%) and low LOD, LOQ (4 and 10 µg/g respectively, with respect to folic acid). The method was applied to the determination of N-nitroso folic acid in 40 supplements containing folic acid with different strengths and formulation. The content of N-nitroso folic acid was found to be up to 898 ng/unit (1794 µg/g with respect to folic acid). It enabled regulatory actions, such as product recall, to safeguard public health from unsafe products. [ABSTRACT FROM AUTHOR]

Objective: Chronic subdural hematoma (CSDH) is a neurological complication following clipping surgery. However, the natural course and ideal approach for the treatment of clipping-related-CSDH (CR-CSDH) have not been clearly established. We aimed to investigate the course of CR-CSDH using chronological radiological findings. Methods: We performed a retrospective analysis of 28 (3.8%) patients who developed CSDH among 736 patients who underwent surgical clipping using pterional approach for unruptured aneurysms at our institution between December 2010 and December 2018. Patients underwent follow-up CT scan 6-8 weeks after clipping surgery and decision to pursue surgical intervention rests upon the patient's symptom based on the Markwalder's grading scale (MGS) and numeric rating scale (NRS). Results: Of the 28 patients, 3 patients (10.7%) underwent surgery, while 25 (89.2%) showed spontaneous resolution of CR-CSDH. Eighteen patients (64.2%) had mild headache with MGS of 0-1. The mean maximum hematoma volume was 41.9±30.9 ml (5.8-135 ml), and 26 patients (92.8%) had homogeneous hematoma. The mean time to hematoma resolution was 126.7±52.9 days (46-228 days). Comparing group of CR-CSDH volume =43 ml or a midline shift =5 mm, the difference in presence of linear low-density area (p=0.002) and age (p=0.026) between the conservative and operative groups were found to be statistically significant. Conclusions: Most CR-CSDH cases spontaneously resolved within 4 months. Therefore, we suggest that close observation should be performed if patient's symptoms are mild and special radiologic findings are present, despite its relatively large volume and midline shifting. [ABSTRACT FROM AUTHOR]