94 research outputs found
Lysosomal protein surface expression discriminates fat- from bone-forming human mesenchymal precursor cells
Tissue resident mesenchymal stem/stromal cells (MSCs) occupy perivascular spaces. Profiling human adipose perivascular mesenchyme with antibody arrays identified 16 novel surface antigens, including endolysosomal protein CD107a. Surface CD107a expression segregates MSCs into functionally distinct subsets. In culture, CD107a(low) cells demonstrate high colony formation, osteoprogenitor cell frequency, and osteogenic potential. Conversely, CD107a(high) cells include almost exclusively adipocyte progenitor cells. Accordingly, human CD107a(low) cells drove dramatic bone formation after intramuscular transplantation in mice, and induced spine fusion in rats, whereas CD107a(high) cells did not. CD107a protein trafficking to the cell surface is associated with exocytosis during early adipogenic differentiation. RNA sequencing also suggested that CD107a(low) cells are precursors of CD107a(high) cells. These results document the molecular and functional diversity of perivascular regenerative cells, and show that relocation to cell surface of a lysosomal protein marks the transition from osteo- to adipogenic potential in native human MSCs, a population of substantial therapeutic interest
Magnetically Responsive Photonic Structures
Magnetically responsive photonic crystals (MRPCs), whose colors can be controlled by external magnetic field, have drawn lots of attention during the past two decades. They are highly desirable for the potential applications, such as sensors and tunable color displays. However it remains difficult to fabricate MRPCs with convenient control, fast response, excellent reversibility and easy integration into advanced devices. In my thesis work, I have focused on the development of novel magnetically responsive photonic structures with rapid and full reversibility. First, superparamagnetic magnetite (Fe3O4) colloidal nanocrystal clusters (CNCs) have been synthesized and employed as building blocks to construct colloidal photonic crystals. The one dimensional periodic chainlike structure whose diffraction can be moved across the entire visible spectral region can be achieved by the application of an external magnetic field. The precise control, fast response and the fully reversible optical properties show great potential in applications such as responsive color displays or sensors. The assembled structures have been studied by using a method that combines magnetic assembly with sol-gel processes to physically fix individual photonic chains. The resulting nanochains exhibit magnetically responsive photonic properties and long-term structural/optical stability. Greatly improved magnetically responsive photonic structures with widely tunable optical properties and long-term stability can be achieved by porous silica coating on the CNCs surface by a novel water based etching method.A new mechanism of stabilizing the magnetic photonic crystals against packing force while keeping the tunability will be shown in the thesis. By taking advantage of agarose gel as a matrix to prevent the photonic structures inside from aggregation, the system shows remarkable stability against an external magnetic field. Other features such as fast, reversible, and tunable optical response to external magnetic fields are well kept in this system. In addition, a bistable color-reflective magnetic tunable photonic film with thermally erasable property will be presented. This film exhibits excellent cycling stability and durability over a long period. The simple fabrication process, easy control over the color change, the superior stability over cycling and prolonged field exposure, and the low cost and energy saving properties allow broad potential applications including outdoor displays
Stable Magnetic Hot Spots for Simultaneous Concentration and Ultrasensitive Surface-Enhanced Raman Scattering Detection of Solution Analytes
A simple and robust strategy is reported in this Article
for the
synthesis of stable magnetic surface-enhanced Raman scattering (SERS)
hot spots in superparamagnetic, raspberry-shaped, mesoscopic gold
particles that are composed of superparamagnetic Fe<sub>3</sub>O<sub>4</sub> cores, amorphous SiO<sub>2</sub> mediation shells, and outer
individual Au nanoparticles. The average interparticle gaps between
the Au nanoparticles can be finely tuned by controlling the synthesis
conditions, resulting in the formation of adequate SERS hot spots.
The magnetic cores provide the capability to concentrate solution
analytes adsorbed on the surfaces of the composite particles with
the assistance of an external magnetic field, leading to ultrasensitive
SERS detection of target species with concentration as low as femtomolar
A Hybrid Probabilistic Risk Analytical Approach to Ship Pilotage Risk Resonance with FRAM
Collision risk in ship pilotage process has complex characteristics that are dynamic, uncertain, and emergent. To reveal collision risk resonance during ship pilotage process, a hybrid probabilistic risk analysis approach is proposed, which integrates the Functional Resonance Analysis Method (FRAM), Dempster–Shafer (D–S) evidence theory, and Monte Carlo (MC) simulation. First, FRAM is used to qualitatively describe the coupling relationship and operation mechanism among the functions of the pilotage operation system. Then, the D–S evidence theory is used to determine the probability distribution of the function output in the specified pilotage scenario after quantitatively expressing the function variability, coupling effect, and the influence of operation conditions through rating scales. Finally, MC simulation is used to calculate the aggregated coupling variability between functions, and the critical couplings and risk resonance paths under different scenarios are identified by setting the threshold and confidence level. The results show that ship collision risk transmission is caused by function resonance in the pilotage system, and the function resonance paths vary with pilotage scenarios. The critical coupling ‘F2-F7(I)’ emerges as a consistent factor in both scenarios, emphasizing the significance of maintaining a proper lookout. The hybrid probabilistic risk analytical approach to ship pilotage risk resonance with FRAM can be a useful method for analysing the causative mechanism of ship operational risk
A Novel Feature Extraction Algorithm and System for Flexible Integrated Circuit Packaging Substrate
Aiming at the line defect detection of a flexible integrated circuit substrate (FICS) without reference template, there are some problems such as line discontinuity or inaccurate line defect location in the detection results. In order to address these problems, a line feature detection algorithm for extracting an FICS image is proposed. Firstly, FICS image acquisition is carried out by using the appearance defect intelligent detection system independently developed in our lab. Secondly, in the algorithm design of the software system, the binary image of the line image to be segmented is obtained after the color FICS image is classified by K-means, median filtering, morphological filling and closed operation. Finally, for an FICS binary image, an image segmentation model with convexity-preserving indirect regular level set is proposed, which is applied to extract the line features of an FICS image. Experiment results show that, compared with the CV model, LBF model, LCV model, LGIF model, Order-LBF model and RSF model, the proposed model can extract line features with high accuracy, and the line boundary is smooth, which lays an important foundation for high-precision measurement of line width and line distance and high-precision location of defects
Research Status and Development of Non-Ferrous Metal Beneficiation Wastewater Treatment
Non-ferrous metal beneficiation wastewater is often acidic or alkaline, and contains a large number of residual reagents, suspended solids and metal ions-based pollutants. With the continuous development and utilization of mineral resources, non-ferrous metal beneficiation wastewater has become a major cause of mine environment, water and soil pollution. The wastewater from mineral processing can not be applied to mineral processing. This was accounted by the fact that all kinds of pollutants can damage mineral processing equipment, affect mineral processing flowsheet and decrease concentrate quality. Therefore, the comprehensive treatment of non-ferrous metal beneficiation wastewater has become an urgent problem that needs to be solved in China and even in the world. This article summarizes the treatment methods of the main pollutants that are generated from non-ferrous metal beneficiation wastewater, expounds the current research status of non-ferrous metal beneficiation wastewater treatment in recent years, looks forward to future development direction of wastewater treatment
Determination of Solvation Layer Thickness by a Magnetophotonic Approach
Derjaguin–Landau–Verwey–Overbeek (DLVO) theory fails in explaining the superior stability of colloid particles in aqueous suspensions under conditions of high ionic strengths where electrostatic forces are effectively screened. Accumulating evidence shows that the formation of a thin rigid layer of solvent molecules in the vicinity of a colloidal particle surface provides an additional repulsive interaction when the interparticle distance is reduced to several nanometers. The effective determination of the thickness of the solvation layer however remains a challenge. Here, we demonstrate a simple yet powerful magnetophotonic technique that can be used to study the thickness of the solvation layers formed on the colloidal silica surface in various polar solvents. A relationship between the hydrogen-bonding ability of the solvents and the thickness of solvation layer on colloidal silica surfaces has been identified; this observation is found to be consistent with the previously proposed hydrogen-bonding origin of the solvation force
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