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We recently developed a novel hyperspectral excitation-resolved near-infrared fluorescence imaging system (HER-NIRF) based on a continuous-wave wavelength-swept laser. In this study, this technique is applied to measure the distribution of the therapeutic agent dimethyl sulfoxide (DMSO) by utilizing solvatochromic shift in the spectral profile of albumin-bound Indocyanine green (ICG). Using wide-field imaging in turbid media, complex dynamics of albumin-bound ICG are measured in mixtures of dimethyl sulfoxide (DMSO) and water. Phantom experiments are conducted to evaluate the performance of the HER-NIRF system. The results show that the distribution of DMSO can be visualized in the wide-field reflection geometry. One of the main purposes of the DMSO is to act as a carrier for other drugs, enhancing their effects by facilitating skin penetration. Understanding the solubility and permeability of drugs in vivo is very important in drug discovery and development. Hence, this HER-NIRF technique has great potential to advance the utilization of the therapeutic agent DMSO by mapping its distribution via the solvatochromic shift of ICG. By customizing the operational wavelength range, this system can be applied to any other fluorophores in the near-infrared region and utilized for a wide variety of drug delivery studies. [ABSTRACT FROM AUTHOR]

Photoacoustic imaging has emerged as a promising biomedical imaging technique that enables visualization of the optical absorption characteristics of biological tissues in vivo. Among the different photoacoustic imaging system configurations, optical-resolution photoacoustic microscopy stands out by providing high spatial resolution using a tightly focused laser beam, which is typically transmitted through optical fibers. Achieving high-quality images depends significantly on optical fluence, which is directly proportional to the signal-to-noise ratio. Hence, optimizing the laser-fiber coupling is critical. Conventional coupling systems require manual adjustment of the optical path to direct the laser beam into the fiber, which is a repetitive and time-consuming process. In this study, we propose an automated laser-fiber coupling module that optimizes laser delivery and minimizes the need for manual intervention. By incorporating a motor-mounted mirror holder and proportional derivative control, we successfully achieved efficient and robust laser delivery. The performance of the proposed system was evaluated using a leaf-skeleton phantom in vitro and a human finger in vivo, resulting in high-quality photoacoustic images. This innovation has the potential to significantly enhance the quality and efficiency of optical-resolution photoacoustic microscopy. [ABSTRACT FROM AUTHOR]

In recent years, bone tissue engineering (BTE) has made significant progress in promoting the direct and functional connection between bone and graft, including osseointegration and osteoconduction, to facilitate the healing of damaged bone tissues. Herein, we introduce a new, environmentally friendly, and cost-effective method for synthesizing reduced graphene oxide (rGO) and hydroxyapatite (HAp). The method uses epigallocatechin-3-O-gallate (EGCG) as a reducing agent to synthesize rGO (E-rGO), and HAp powder is obtained from Atlantic bluefin tuna (Thunnus thynnus). The physicochemical analysis indicated that the E-rGO/HAp composites had exceptional properties for use as BTE scaffolds, as well as high purity. Moreover, we discovered that E-rGO/HAp composites facilitated not only the proliferation, but also early and late osteogenic differentiation of human mesenchymal stem cells (hMSCs). Our work suggests that E-rGO/HAp composites may play a significant role in promoting the spontaneous osteogenic differentiation of hMSCs, and we envision that E-rGO/HAp composites could serve as promising candidates for BTE scaffolds, stem-cell differentiation stimulators, and implantable device components because of their biocompatible and bioactive properties. Overall, we suggest a new approach for developing cost-effective and environmentally friendly E-rGO/HAp composite materials for BTE application. [ABSTRACT FROM AUTHOR]

We demonstrate a novel narrow-linewidth configuration of a wavelength-swept active mode locking (AML) fiber laser. The frequency response of the modulation depth of a semiconductor optical amplifier can be improved in a higher modulation frequency region by adapting the cross gain modulation (XGM) configuration, compared to that of the conventional direct gain modulation (DGM) configuration. As a sufficient modulation depth is implemented for an AML at higher modulation frequencies at around gigahertz order, it results in a narrower linewidth of lasing output. For the same modulation frequency of 1361.25 MHz, the linewidth of 0.25 nm with DGM becomes narrower up to 0.113 nm with XGM, which corresponds to an improved point spread function with 1.41 mm of 6-dB roll-off. [ABSTRACT FROM AUTHOR]

Prickly sow thistle, Sonchus asper (L.) Hill, and common sow thistle, Sonchus oleraceus L., are noxious weeds. Probably originating from the Mediterranean region, they have become widespread species. They share similar morphology and are closely related. However, they differ in their chromosome numbers and the precise relationship between them remains uncertain. Understanding their chloroplast genome structure and evolution is an important initial step toward determining their phylogenetic relationships and analyzing accelerating plant invasion processes on a global scale. We assembled four accessions of chloroplast genomes (two S. asper and two S. oleraceus) by the next generation sequencing approach and conducted comparative genomic analyses. All the chloroplast genomes were highly conserved. Their sizes ranged from 151,808 to 151,849 bp, containing 130 genes including 87 coding genes, 6 rRNA genes, and 37 tRNA genes. Phylogenetic analysis based on the whole chloroplast genome sequences showed that S. asper shares a recent common ancestor with S. oleraceus and suggested its likely involvement in a possible amphidiploid origin of S. oleraceus. In total, 79 simple sequence repeats and highly variable regions were identified as the potential chloroplast markers to determine genetic variation and colonization patterns of Sonchus species. [ABSTRACT FROM AUTHOR]

A new type of quasi-distributed sensor system is implemented using an active mode locking (AML) laser cavity with multiple partially reflecting segments. The mode locking frequency of the AML laser is linearly proportional to the overall lasing cavity length. To implement multiple resonators having multiple reflection points installed in a sensing fiber, two types of partial reflectors (PRs) are implemented for an in-line configuration, one with fiber Bragg grating and the other with a fiber Fabry–Perot interferometer. Since the laser has oscillated only when the modulation frequencies for the mode locking frequency match with the corresponding resonator lengths, it is possible to read the multiple partially reflecting segments along the sensing fiber. The difference between two corresponding mode locking frequencies is changing proportionally with the segment length variation between two PRs upon strain application. The segment length change caused by the applied strain can be successfully measured with a linear sensitivity between mode locking frequency and displacement, linearity over 0.99, and spatial position resolution below meter order. [ABSTRACT FROM AUTHOR]

In this study, we designed and synthesized eight thiophene chalcone derivatives (1a–h) as tyrosinase inhibitors and evaluated their mushroom tyrosinase inhibitory activities. Of these eight compounds, (E)-3-(2,4-dihydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one (1c) showed strong competitive inhibition activity against mushroom tyrosinase with IC50 values of 0.013 μM for tyrosine hydroxylase and 0.93 μM for dopa oxidase. In addition, we used enzyme kinetics study and docking program to further evaluate the inhibitory mechanism of 1c toward tyrosinase. As an underlying mechanism of 1c mediated anti-melanogenic effect, we investigated the inhibitory activity against melanin contents and cellular tyrosinase in B16F10 melanoma cells. As the results, the enzyme kinetics and docking results supports that 1c highly interacts with tyrosinase residues in the tyrosinase active site and it can directly inhibit tyrosinase as competitive inhibitor. In addition, 1c exhibited dose-dependent inhibitory effects in melanin contents and intracellular tyrosinase on α-MSH and IBMX-induced B16F10 cells. Overall, our results suggested that 1c might be considered potent tyrosinase inhibitor for use in the development of therapeutic agents for diseases associated with hyperpigment disorders. [ABSTRACT FROM AUTHOR]

Diffuse optical tomography (DOT) has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing (FDM) DOT systems to analyze their performance with respect to acquisition time and imaging quality, in comparison with the conventional time-division multiplexing (TDM) DOT. A large tomographic area of a cylindrical phantom 60 mm in diameter could be successfully reconstructed using both TDM DOT and FDM DOT systems. In our experiment with 6 source-detector (S-D) pairs, the TDM DOT and FDM DOT systems required 6.18 and 1 s, respectively, to obtain a single tomographic data set. While the absorption coefficient of the reconstruction image was underestimated in the case of the FDM DOT, we experimentally confirmed that the abnormal region can be clearly distinguished from the background phantom using both methods., Competing Interests: The authors declare no conflict of interest.

We demonstrate a novel wavelength-comb-swept laser based on two intra-cavity filters: an acousto-optic tunable filter (AOTF) and a Fabry-Pérot etalon filter. The AOTF is used for the tunable selection of the output wavelength with time and the etalon filter for the narrowing of the spectral linewidth to extend the coherence length. Compared to the conventional wavelength-swept laser, the acousto-optic-based wavelength-comb-swept laser (WCSL) can extend the measureable range of displacement measurements by decreasing the sensitivity roll-off of the point spread function. Because the AOTF contains no mechanical moving parts to select the output wavelength acousto-optically, the WCSL source has a high wavenumber ( k ) linearity of R ² = 0.9999 to ensure equally spaced wavelength combs in the wavenumber domain.

We have developed a modified optical frequency domain imaging (OFDI) system that performs parallel imaging of three-dimensional (3D) surface profiles by using the space division multiplexing (SDM) method with dual-area swept sourced beams. We have also demonstrated that 3D surface information for two different areas could be well obtained in a same time with only one camera by our method. In this study, double field of views (FOVs) of 11.16 mm × 5.92 mm were achieved within 0.5 s. Height range for each FOV was 460 µm and axial and transverse resolutions were 3.6 and 5.52 µm, respectively.

A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated with a repetition rate of 0.2 Hz by using this FBG sensor interrogation system.

Multiple wavelength light sources in the medical spectral window region are useful for various medical sensing applications in tissue by distinguishing the absorption and scattering coefficients optically. We propose a simultaneous second harmonic generation of multiple wavelength fiber laser output using parallel channels of periodically-poled lithium niobate (PPLN) waveguides. High intensity dual wavelength lasing output is experimentally realized with two tunable fiber Bragg gratings of 1,547.20 nm and 1,554.48 nm for the efficient conversion to the half wavelengths, 773.60 nm and 777.24 nm, by using two parallel PPLN channels. Compared with a conventional dual second harmonic generation (SHG) configuration based on two different input wavelengths from each independent light source, this method has a relatively higher efficiency to align the input light beam into the adjacent parallel PPLN channels simultaneously. The use of fiber lasers offers several advantages since they are relatively inexpensive, provide high power in excess of tens of watts, are widely tunable, and can produce pulses from milliseconds to femtoseconds.

In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor.