Wide-field color imaging through multimode fiber with single wavelength illumination: plug-and-play approach.

Multimode fiber (MMF) is extensively studied for its ability to transmit light modes in parallel, potentially minimizing optical fiber size in imaging. However, current research predominantly focuses on grayscale imaging, with limited attention to color studies. Existing colorization methods often involve costly white light lasers or multiple light sources, increasing optical system expenses and space. To achieve wide-field color images with typical monochromatic illumination MMF imaging system, we proposed a data-driven "colorization" approach and a neural network called SpeckleColorNet, merging U-Net and conditional GAN (cGAN) architectures, trained by a combined loss function. This approach, demonstrated on a 2-meter MMF system with single-wavelength illumination and the Peripheral Blood Cell (PBC) dataset, outperforms grayscale imaging and alternative colorization methods in readability, definition, detail, and accuracy. Our method aims to integrate MMF into clinical medicine and industrial monitoring, offering cost-effective high-fidelity color imaging. It serves as a plug-and-play replacement for conventional grayscale algorithms in MMF systems, eliminating the need for additional hardware.

Super-resolution lensless on-chip microscopy based on array illumination and sub-pixel shift search.

The resolution of a lensless on-chip microscopy system is constrained by the pixel size of image sensors. This Letter introduces a super-resolution on-chip microscopy system based on a compact array light source illumination and sub-pixel shift search. The system utilizes a closely spaced array light source composed by four RGB LED modules, sequentially illuminating the sample. A sub-pixel shift search algorithm is proposed, which determines the sub-pixel shift by comparing the frequency of captured low-resolution holograms. Leveraging this sub-pixel shift, a super-resolution reconstruction algorithm is introduced, building upon a multi-wavelength phase retrieval method, enabling the rapid super-resolution reconstruction of holograms with the region-of-interest. The system and algorithms presented herein obviate the need for a displacement control platform and calibration of the illumination angles of the light source, facilitating a super-resolution phase reconstruction under partially coherent illumination.

CFZA camera: a high-resolution lensless imaging technique based on compound Fresnel zone aperture.

In lensless imaging using a Fresnel zone aperture (FZA), it is generally believed that the resolution is limited by the outermost ring breadth of the FZA. The limitation has the potential to be broken according to the multi-order property of binary FZAs. In this Letter, we propose to use a high-order component of the FZA as the point spread function (PSF) to develop a high-order transfer function backpropagation (HBP) algorithm to enhance the resolution. The proportion of high-order diffraction energy is low, leading to severe defocus noise in the reconstructed image. To address this issue, we propose a Compound FZA (CFZA), which merges two partial FZAs operating at different orders as the mask to strike a balance between the noise and resolution. Experimental results verify that the CFZA-based camera has a resolution that is double that of a traditional FZA-based camera with an identical outer ring breadth and can be reconstructed with high quality by a single HBP without calibration. Our method offers a cost-effective solution for achieving high-resolution imaging, expanding the potential applications of FZA-based lensless imaging in a variety of areas.

VGLL4-TEAD1 promotes vascular smooth muscle cell differentiation from human pluripotent stem cells via TET2.

The Hippo signaling pathway plays a critical role in cardiovascular development and stem cell differentiation. Using microarray profiling, we found that the Hippo pathway components vestigial-like family member 4 (VGLL4) and TEA domain transcription factor 1 (TEAD1) were upregulated during vascular smooth muscle cell (VSMC) differentiation from H1 ESCs (H1 embryonic stem cells). To further explore the role and molecular mechanisms of VGLL4 in regulating VSMC differentiation, we generated a VGLL4-knockdown H1 ESC line (heterozygous knockout) using the CRISPR/Cas9 system and found that VGLL4 knockdown inhibited VSMC specification. In contrast, overexpression of VGLL4 using the PiggyBac transposon system facilitated VSMC differentiation. We confirmed that this effect was mediated via TEAD1 and VGLL4 interaction. In addition, bioinformatics analysis revealed that Ten-eleven-translocation 2 (TET2), a DNA dioxygenase, is a target of TEAD1, and a luciferase assay further verified that TET2 is the target of the VGLL4-TEAD1 complex. Indeed, TET2 overexpression promoted VSMC marker gene expression and countered the VGLL4 knockdown-mediated inhibitory effects on VSMC differentiation. In summary, we revealed a novel role of VGLL4 in promoting VSMC differentiation from hESCs and identified TET2 as a new target of the VGLL4-TEAD1 complex, which may demethylate VSMC marker genes and facilitate VSMC differentiation. This study provides new insights into the VGLL4-TEAD1-TET2 axis in VSMC differentiation and vascular development.

High extraction efficiency phosphor design applied in laser lighting.

Laser lighting has great potential to be the next generation of general lighting due to its high brightness and directionality. However, the light extraction efficiency and luminous efficiency from the light exit surface are greatly limited since phosphor structure. Here, we design and optimize a phosphor structure by Monte Carlo method (MCM) with optimization algorithm. The results indicate that the optimized Ce:YAG single crystal phosphor is able to improve the extraction efficiency to 0.49, which is much higher than the conventional parallel phosphor. The luminous efficiency of the optimized phosphor can also reach 230 lm/W. In addition, the experiments and simulations show that the extraction efficiency and luminous efficiency will reduce to 0.41 and 190 lm/W if there is scattering in the optimized phosphor. The spatial distribution of the light intensity and thermal stability of the optimized phosphor are also measured. The optimized phosphor is helpful to the design of side heat dissipation structure. In general, the optimized phosphor may play a significant role in the high-flux laser lighting and the method also provides a universal tool for the phosphor design.

Extended angular-spectrum modeling (EASM) of light energy transport in scattering media.

The exact modeling of light transport in scattering media is critical in biological imaging, free-space communication, and phosphor-converted lighting. Angular spectrum is proved to be a fast and effective approach to reconstructing the wavefront dynamics during the propagation in scattering media, however, finding it difficult in acquiring the wavefront and energy change simultaneously. Besides, conventional methods for energy tracing, such as the Monte Carlo method, are inefficient in speed and hard to simulate the wavefront change. Here, we propose an extended angular-spectrum modeling (EASM) approach using tenuous scattering approximate solutions to obtain a time-efficient and accurate method for reconstruction of energy and wavefront dynamics in various scattering media. The generality of our method is numerically simulated and experimentally verified with a set of scattering media with different properties. EASM has a time advantage under the guarantee of calculation accuracy, especially when calculating several thickness changes after the calculation model is established. Furthermore, multi-layered media can also be simulated by EASM with a good precision. The results suggest that EASM performs certain computations more efficiently than the conventional method and thus provides an effective and flexible calculation tool for scattering media.

Amp-vortex edge-camera: a lensless multi-modality imaging system with edge enhancement.

We demonstrate a lensless imaging system with edge-enhanced imaging constructed with a Fresnel zone aperture (FZA) mask placed 3 mm away from a CMOS sensor. We propose vortex back-propagation (vortex-BP) and amplitude vortex-BP algorithms for the FZA-based lensless imaging system to remove the noise and achieve the fast reconstruction of high contrast edge enhancement. Directionally controlled anisotropic edge enhancement can be achieved with our proposed superimposed vortex-BP algorithm. With different reconstruction algorithms, the proposed amp-vortex edge-camera in this paper can achieve 2D bright filed imaging, isotropic, and directional controllable anisotropic edge-enhanced imaging with incoherent light illumination, by a single-shot captured hologram. The effect of edge detection is the same as optical edge detection, which is the re-distribution of light energy. Noise-free in-focus edge detection can be achieved by using back-propagation, without a de-noise algorithm, which is an advantage over other lensless imaging technologies. This is expected to be widely used in autonomous driving, artificial intelligence recognition in consumer electronics, etc.

Nyquist Sampling Conditions of Some Diffraction Algorithms with Adjustable Magnification.

Diffraction algorithms with adjustable magnification are dominant in holographic projection and imaging. However, the algorithms are limited by the Nyquist sampling conditions, and simulation results with inappropriate parameters sometimes appear with aliasing. At present, many diffraction algorithms have been proposed and improved, but there is a need for an overall analysis of their sampling conditions. In this paper, some classical diffraction algorithms with adjustable magnification are summarized, and their sampling conditions in the case of plane wave or spherical wave illumination are analyzed and compared, which helps to select the appropriate diffraction algorithm according to the specific parameter conditions of the simulation to avoid aliasing.

YAP inhibition promotes endothelial cell differentiation from pluripotent stem cell through EC master transcription factor FLI1.

Endothelial cells (ECs) derived from pluripotent stem cells (PSCs) provide great resource for vascular disease modeling and cell-based regeneration therapy. However, the molecular mechanisms of EC differentiation are not completely understood. In this study, we checked transcriptional profile by microarray and found Hippo pathway is changed and the activity of YAP decreased during mesoderm-mediated EC differentiation from human embryonic stem cells (hESCs). Knockdown of YAP in hESCs promoted both mesoderm and EC differentiation indicating by mesodermal- or EC-specific marker gene expression increased both in mRNA and protein level. In contrast, overexpression of YAP inhibited mesoderm and EC differentiation. Microarray data showed that several key transcription factors of EC differentiation, such as FLI1, ERG, SOX17 are upregulated. Interestingly, knockdown YAP enhanced the expression of these master transcription factors. Bioinformation analysis revealed that TEAD, a YAP binds transcription factors, might regulate the expression of EC master TFs, including FLI1. Luciferase assay confirmed that YAP binds to TEAD1, which would inhibit FLI1 expression. Finally, FLI1 overexpression rescued the effects of YAP overexpression-mediated inhibition of EC differentiation. In conclusion, we revealed the inhibitory effects of YAP on EC differentiation from PSCs, and YAP inhibition might promote expression of master TFs FLI1 for EC commitment through interacting with TEAD1, which might provide an idea for EC differentiation and vascular regeneration via manipulating YAP signaling.

Critical role of VGLL4 in the regulation of chronic normobaric hypoxia-induced pulmonary hypertension in mice.

Pulmonary hypertension (PH), a rare but deadly cardiopulmonary disorder, is characterized by extensive remodeling of pulmonary arteries resulting from enhancement of pulmonary artery smooth muscle cell proliferation and suppressed apoptosis; however, the underlying pathophysiological mechanisms remain largely unknown. Recently, epigenetics has gained increasing prominence in the development of PH. We aimed to investigate the role of vestigial-like family member 4 (VGLL4) in chronic normobaric hypoxia (CNH)-induced PH and to address whether it is associated with epigenetic regulation. The rodent model of PH was established by CNH treatment (10% O2 , 23 hours/day). Western blot, quantitative reverse transcription polymerase chain reaction, immunofluorescence, immunoprecipitation, and adeno-associated virus tests were performed to explore the potential mechanisms involved in CNH-induced PH in mice. VGLL4 expression was upregulated and correlated with CNH in PH mouse lung tissues in a time-dependent manner. VGLL4 colocalized with α-smooth muscle actin in cultured pulmonary arterial smooth muscle cells (PASMCs), and VGLL4 immunoactivity was increased in PASMCs following hypoxia exposure in vitro. VGLL4 knockdown attenuated CNH-induced PH and pulmonary artery remodeling by blunting signal transducer and activator of transcription 3 (STAT3) signaling; conversely, VGLL4 overexpression exacerbated the development of PH. CNH enhanced the acetylation of VGLL4 and increased the interaction of ac-H3K9/VGLL4 and ac-H3K9/STAT3 in the lung tissues, and levels of ac-H3K9, p-STAT3/STAT3, and proliferation-associated protein levels were markedly up-regulated, whereas apoptosis-related protein levels were significantly downregulated, in the lung tissues of mice with CNH-induced PH. Notably, abrogation of VGLL4 acetylation reversed CNH-induced PH and pulmonary artery remodeling and suppressed STAT3 signaling. Finally, STAT3 knockdown alleviated CNH-induced PH. In conclusion, VGLL4 acetylation upregulation could contribute to CNH-induced PH and pulmonary artery remodeling via STAT3 signaling, and abrogation of VGLL4 acetylation reversed CNH-induced PH. Pharmacological or genetic deletion of VGLL4 might be a potential target for therapeutic interventions in CNH-induced PH.