BACKGROUND: Extrauterine growth restriction (EUGR) represents a prevalent condition observed in preterm neonates, which poses potential adverse implications for both neonatal development and long-term health outcomes. The manifestation of EUGR has been intricately associated with perturbations in microbial and metabolic profiles. This study aimed to investigate the characteristics of the gut microbial network in early colonizers among preterm neonates with EUGR. METHODS: Twenty-nine preterm infants participated in this study, comprising 14 subjects in the EUGR group and 15 in the normal growth (AGA) group. Meconium (D1) and fecal samples were collected at postnatal day 28 (D28) and 1 month after discharge (M1). Subsequently, total bacterial DNA was extracted and sequenced using the Illumina MiSeq system, targeting the V3-V4 hyper-variable regions of the 16S rRNA gene. RESULTS: The outcomes of principal coordinates analysis (PCoA) and examination of the microbial network structure revealed distinctive developmental trajectories in the gut microbiome during the initial three months of life among preterm neonates with and without EUGR. Significant differences in microbial community were observed at the D1 (P = 0.039) and M1 phases (P = 0.036) between the EUGR and AGA groups, while a comparable microbial community was noted at the D28 phase (P = 0.414). Moreover, relative to the AGA group, the EUGR group exhibited significantly lower relative abundances of bacteria associated with secretion of short-chain fatty acids, including Lactobacillus (P = 0.041) and Parabacteroides (P = 0.033) at the D1 phase, Bifidobacterium at the D28 phase, and genera Dysgonomonas (P = 0.042), Dialister (P = 0.02), Dorea (P = 0.042), and Fusobacterium (P = 0.017) at the M1 phase. CONCLUSION: Overall, the present findings offer crucial important insights into the distinctive gut microbial signatures exhibited by earlier colonizers in preterm neonates with EUGR. Further mechanistic studies are needed to establish whether these differences are the cause or a consequence of EUGR.
Gastrointestinal Microbiome , Infant, Premature , Infant , Infant, Newborn , Humans , Gestational Age , RNA, Ribosomal, 16S/genetics , Birth Weight
Due to the constraints imposed by physical effects and performance degradation, silicon-based chip technology is facing certain limitations in sustaining the advancement of Moore's law. Two-dimensional (2D) materials have emerged as highly promising candidates for the post-Moore era, offering significant potential in domains such as integrated circuits and next-generation computing. Here, in this review, the progress of 2D semiconductors in process engineering and various electronic applications are summarized. A careful introduction of material synthesis, transistor engineering focused on device configuration, dielectric engineering, contact engineering, and material integration are given first. Then 2D transistors for certain electronic applications including digital and analog circuits, heterogeneous integration chips, and sensing circuits are discussed. Moreover, several promising applications (artificial intelligence chips and quantum chips) based on specific mechanism devices are introduced. Finally, the challenges for 2D materials encountered in achieving circuit-level or system-level applications are analyzed, and potential development pathways or roadmaps are further speculated and outlooked.
Random speckle patterns contain valuable information about the incident light. Researchers have successfully constructed spectrometers and wavemeters by utilizing the speckles generated by inter-mode interferences of a multimode fiber (MMF). However, cameras were often employed to record the speckle data in previous reports. The camera's high cost (especially in the near-infrared range), large size, and low response speed limit the applications in optical communications, metrology, and optical sensing. A seven-core fiber (SCF) was fused with an MMF to capture the speckle pattern, where each core coupled part of the speckle field. Furthermore, we take advantage of the space division multiplexing capability of the SCF by incorporating an optical switch. This allows the variety of speckles generated by the incidence of different cores into the MMF. A convolutional neural network (CNN) regression algorithm was designed to analyze the complicated speckle data. The experimental results show that the proposed wavemeter can resolve adjacent wavelengths of 1 pm with an error of about 0.2 pm. We also discussed how different lengths of MMF influence the wavelength resolution. In conclusion, our research presents a robust and cost-effective approach to a wavelength measurement device by use of a seven-core optical fiber.
Novel complex C2-quaternary-indol-3-one units bearing versatile nitro groups have been successfully developed from pseudo-indolones and α,ß-unsaturated nitroolefins through rhodium-catalyzed C-H activation/[3 + 2] spirocyclization. Notably, four diastereomers could be selectively obtained in the reaction by condition control.
Ketones , Rhodium , Catalysis , Indoles
Fiber Bragg gratings (FBGs) have been widely employed as a sensor for temperature, vibration, strain, etc. measurements. However, extant methods for FBG interrogation still face challenges in the aspects of sensitivity, measurement speed, and cost. In this Letter, we introduced random speckles as the FBG's reflection spectrum information carrier for demodulation. Instead of the commonly used InGaAs cameras, a quadrant detector (QD) was first utilized to record the speckle patterns in the experiments. Although the speckle images were severely compressed into four channel signals by the QD, the spectral features of the FBGs can still be precisely extracted with the assistance of a deep convolution neural network (CNN). The temperature and vibration experiments were demonstrated with a resolution of 1.2 pm. These results show that the new, to the best of our knowledge, speckle-based demodulation scheme can satisfy the requirements of both high-resolution and high-speed measurements, which should pave a new way for the optical fiber sensors.
Fiber optical power splitters (OPSs) have been widely employed in optical communications, optical sensors, optical measurements, and optical fiber lasers. It has been found that OPSs with variable power ratios can simplify the structure and increase the flexibility of optical systems. In this study, a variable-fiber OPS based on a triangular prism is proposed and demonstrated. By adjusting the output beam width of the prism, the power ratio can be continuously tuned. The optical simulations show that the horizontal displacement design is better than the traditional tilt angle design. Our scheme combines a dual-fiber collimator, a focus lens, and a triangular prism with a vertex angle of 120°. By changing the axial displacement of the prism, the power splitting ratio can be altered from 50:50 to 90:10. The polarization and wavelength dependence of the variable OPS were also investigated.
We proposed and experimentally demonstrated a broadband terahertz (THz) metamaterial absorber based on a symmetrical L-shaped metallic resonator. The absorber structure produces two absorption peaks at 0.491 and 0.73 THz, with the absorption rates of 98.6% and 99.6%, respectively. Broadband absorption was obtained from 0.457 to 1 THz, achieving a >90% absorption bandwidth of 0.543 THz. By analyzing the distributions of the electric and magnetic field at the two resonance frequencies, electric and magnetic dipole resonances were proposed to explain the broadband absorption mechanism. Furthermore, various widths and lengths of the symmetrical L-shaped metallic resonator on the absorption characteristics were investigated. Moreover, the broadband absorption characteristic can be maintained with an incident angle of up to 45° for transverse-electric and 30° for transverse-magnetic polarization. Finally, we experimentally observed a >70% broadband absorption characteristic from 0.42 to 1 THz. This proposed absorber has the potential for bolometric imaging, modulating, and spectroscopy in the THz region.
Speckle patterns have been widely employed as a method for precisely determining the wavelength of monochromatic light. In order to achieve higher wavelength precision, a variety of optical diffusing waveguides have been investigated with a focus on their wavelength sensitivity. However, it has been a challenge to find a balance among the cost, compactness, precision, and stability of the waveguide. In this work, we designed a compact cylindrical random scattering waveguide (CRSW) as the light diffuser by mixing TiO2 particles and ultra-violate adhesive. In the CRSW, speckle patterns are generated by input light scattering off TiO2 particles multiple times. Additionally, a thin layer of upconversion nanoparticles (UCNPs) was sprayed on the end face of CRSW to allow near-infrared (NIR) light to be converted to visible light, breaking the imaging limitations of visible cameras in the NIR range. We, then, further designed a convolution neural network (CNN) to recognize the wavelength of the speckle patterns with excellent robustness and ability to transfer learning. This resulted in the achievement of a high wavelength precision of 20 kHz (â¼0.16 fm) at around 1550 nm with a temperature resistance of ±2 °C. Our results demonstrate a low-cost, compact, and simple NIR wavemeter, which is capable of ultra-high wavelength precision and good temperature stability. It has significant value for applications in high-speed and high-precision laser wavelength measurements.
Single fiber scanners (SFSs), with the advantages of compact size, versatility, large field of view, and high resolution, have been applied in many areas. However, image distortions persistently impair the imaging quality of the SFS, although many efforts have been made to address the problem. In this Letter, we propose a simple and complete solution by combining the piezoelectric (PZT) self-induction sensor and machine learning algorithms. The PZT tube was utilized as both the actuator and the fiber position sensor. Additionally, the feedback sensor signal was interrogated by a convolution neural network to eliminate the noise. The experimental results show that the predicted fiber trajectory error was below 0.1%. Moreover, this self-calibration SFS has an excellent robustness to temperature changes (20-50°C). It is believed that the proposed solution has removed the biggest barrier for the SFS and greatly improved its performance and stability in complex environments.
As an efficient, noninvasive, and high spatiotemporal resolved approach, photodynamic therapy (PDT) has high therapeutic potential for cancer treatment, whereas its development still faces a number of challenges, such as the lack of efficient and stable photosensitizers (PSs) and the inadequate ability of PSs to accumulate at tumor sites and target responses. Herein, a pH-responsive calcium carbonate (CaCO3)-mineralized AIEgen nanoprobe was prepared by using bovine serum albumin as the skeleton and loaded with a mitochondria-specific aggregation-induced emission (AIE)-active PS of 1-methyl-4-(4-(1,2,2-triphenylvinyl)styryl)quinolinium iodide (TPE-Qu+), which exhibits superior singlet oxygen (1O2)-generation ability and meanwhile possesses a bright near-infrared fluorescence emission. The biomineralized nanoparticles have small sizes (100 ± 10 nm) with good water dispersion and stability. With an increase in acidity (pH = 7.4-5.0), the internal TPE-Qu+ molecules are released gradually and accumulated in the mitochondria due to their hydrophobicity and electropositivity and then generate fluorescence emission and PDT under an external light source. Tumor inhibition and low acute toxicity were further successfully confirmed by the intracellular uptake test and 4T1-tumor-bearing mouse model.
Neoplasms , Photochemotherapy , Animals , Biomineralization , Hydrogen-Ion Concentration , Mice , Neoplasms/diagnostic imaging , Photochemotherapy/methods , Photosensitizing Agents/pharmacology
A near-infrared spectrometer based on offset fused multimode fiber (MMF) is investigated in this study. The light spectrum is recovered by analyzing the speckle images when light is passing through the MMF. In order to generate adequate speckles, a polarization maintaining fiber (PMF) and a 30 cm long MMF are fused with a vertical offset. Seven different offset displacements are implemented in the fiber fusion. The follow-up experiments show that the fiber offset fusion has a significant influence on the spectral correlation and the resolution. Larger offset fusion can excite more high-order modes in the MMF, and it greatly improves the spectrometer's performance. The simulation results also show that more modes are excited in MMF, and the increase of mode number leads to lower correlation coefficients of the neighboring spectral channels. However, large offset fusion increases the fusion and the insertion loss of the whole system, which may bring difficulties in the low-light cases. In addition, an image denoising algorithm based on dynamic threshold filtering and a spectral reconstruction algorithm originated from complete orthogonal decomposition were used to remove the speckle pattern noise and recover the spectrum. The final speckle-based spectrometer has a spectral resolution of 0.6â¼0.016nm depending on the different offset fusions.
For the first time, we studied the effect of structural relaxation on the NIR spectroscopic properties of bismuth-activated germanium glasses below glass transition temperature. Interestingly, distinct change behavior of NIR luminescence is observed at two different heat-treatment temperature ranges corresponding to two different relaxation behavior of glass structure. Besides, when structural modified by partly substituting B(2)O(3) for GeO(2), a narrower and more thermal sensitive luminescence is observed, which is inexplicable by "inhomogeneous broadening" and we tentatively attribute it to a defect-involved reason. Fundamentally the results here not only provide us a deeper insight into the optical property of bismuth-activated materials but also increase our understanding of the glassy state, and practically it delivers some valuable guidance in designing bismuth-activated glasses with superior NIR optical properties.
A novel Er-doped silica fiber, with heavy Er doping, was specially developed for application to a single frequency fiber laser. Two high temperature-sustainable fiber Bragg gratings, written into Bi-Ge codoped photosensitive fiber, were chosen for the application and spliced to the specialist Er doped silica fiber to form a compact, linear cavity, fiber laser. The fiber laser retained single mode oscillation over a wide temperature range, from room temperature to 400 degrees C. The wavelength of the laser output could be tuned smoothly, without mode hopping being observed, when the temperature was changed. A narrow linewidth of less than 1 kHz was measured at the output of fiber laser and this indicates the potential of the fibre laser sensing system with extremely high sensitivity and resolution over this wide range.
