Numerical optimization of auxiliary biaxial receiver to detect blind zone of pulsed coherent wind lidar.

The conventional pulsed monostatic coaxial coherent Doppler wind lidar (CDWL) has a blind detection zone of tens of meters, causing the loss of near-field wind field data. While maintaining the long-range detection capabilities of pulsed lidar, we introduce a novel auxiliary biaxial receiver (ABR) aimed at acquiring dependable coherent signals within blind zones. This is achieved by incorporating a receiver in close proximity to the monostatic coaxial transceiver (MCT), thereby mitigating end-face reflections and laser pulse tailing effects. A specific model of multiple aperture coherent wind detection is established for the ABR system without blind zone problem (BZP). The numerical simulations demonstrate that the biaxial receiver with reasonable design can meet the detection needs of the entire range of the blind zone. By using an ABR with a smaller focal length under appropriate transceiver pointing and general pointing accuracy, the BZP can be solved. The study also exhaustively obtained all parameter combinations that can solve the near-field BZP for a specific system. The results provide a new idea and engineering design guidance for the optical system design of pulsed CDWL without BZP.

Dendritic unzipped carbon nanofibers enable uniform loading of surfactant-free Pd nanoparticles for the electroanalysis of small biomolecules.

In this study, graphene nanofibers (GNF), which are a superior support material, are successfully synthesized via the dendritic unzipping of stacked-cup carbon nanofibers (SCNF). Ultrasmall Pd nanoparticles are uniformly dispersed on the GNF (Pd/GNF) via chemical reduction under mild conditions without any surfactant involved. The components and structure of Pd/GNF are evaluated via scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Raman spectra and X-ray photoelectron spectroscopy (XPS). The characterization results indicate that the Pd nanoparticles have a uniform size of 3-6 nm without significant aggregation and the overall Pd content is about 11.2 wt% in the Pd/GNF composite. Moreover, a modified electrochemical sensor based on the Pd/GNF composite is successfully fabricated. In the two investigated redox probes (IrCl6 2- and [Fe(CN)6]3-), Pd/GNF shows a superior electrochemical response compared to the Pd nanoparticles loaded on SCNF and bare glass carbon electrode. For the detection of small biomolecules, Pd/GNF could individually or simultaneously detect ascorbic acid (AA), dopamine (DA) and uric acid (UA) through differential pulse voltammetry. The linear concentration ranges of UA, DA and AA are 0.1-1200 µM, 1-180 µM and 0.1-6000 µM, respectively.

Xeno-free culture of human pluripotent stem cells on oligopeptide-grafted hydrogels with various molecular designs.

Establishing cultures of human embryonic (ES) and induced pluripotent (iPS) stem cells in xeno-free conditions is essential for producing clinical-grade cells. Development of cell culture biomaterials for human ES and iPS cells is critical for this purpose. We designed several structures of oligopeptide-grafted poly (vinyl alcohol-co-itaconic acid) hydrogels with optimal elasticity, and prepared them in formations of single chain, single chain with joint segment, dual chain with joint segment, and branched-type chain. Oligopeptide sequences were selected from integrin- and glycosaminoglycan-binding domains of the extracellular matrix. The hydrogels grafted with vitronectin-derived oligopeptides having a joint segment or a dual chain, which has a storage modulus of 25 kPa, supported the long-term culture of human ES and iPS cells for over 10 passages. The dual chain and/or joint segment with cell adhesion molecules on the hydrogels facilitated the proliferation and pluripotency of human ES and iPS cells.