Search

Tin bronze was cladded on bare steel and nickel-plated steel to fabricate the tin bronze/steel bimetallic materials. The interfacial microstructures and infiltrated cracks in the bimetallic materials were investigated. As the tin bronze was cladded on the bare steel, metallurgical bonding was achieved, and a transition layer with BCC-Fe structure was generated at the tin bronze/steel interface. Infiltrated cracks originated from the interface and propagated into the interior of the steel along the grain boundaries. The main infiltrated crack had branch infiltrated cracks and most of the infiltrated cracks were less than 100 μm. The composition of infiltrated crack was similar to the tin bronze layer, and the infiltrated crack was composed of α-Cu (Sn) phase and δ-Cu41Sn11 phase. The infiltrated cracks could not deform synchronously with the steel matrix, and infiltrated cracks could evolve into macro cracks under lower stress and strain during the in situ tensile experiment. Cracking occurred not only in the boundary between the tin bronze and steel but also occurred in the interior of the tin bronze. Two kinds of fracture zone existed in the fracture including the ductile fracture zone and brittle fracture zone. As the tin bronze was cladded on the nickel-plated steel, a transition layer with BCC-Fe structure was also generated between the tin bronze and steel. Nickel was enriched at the interface and grain boundaries. The infiltrated cracks were eliminated. The nickel-segregated grain boundary could not evolve into macro crack during the in situ tensile process. [ABSTRACT FROM AUTHOR]

The influences of Co content on the microstructures and magnetic properties of the anisotropic bulk TbCu7-type Sm-Co nanocrystalline magnets prepared by high-pressure thermal compression (HPTC) from amorphous SmCox precursors with $6.37 \le x \le 8.5$ had been investigated. We found that with Co content $x = 6.37$ , the TbCu7-type Sm-Co phase and a small amount of CaCu5-type Sm-Co crystallized from the precursors; from $x = 6.7$ to $x = 8.5$ , only single TbCu7-type Sm-Co phase generated during the HPTC process. When $x = 6.37$ , an obvious ($00l$) texture was formed, and with increasing Co content, the ($00l$) texture of the synthesized magnets showed a decreasing trend. With increasing Co content, the remanence $B_{\mathrm{ r}}$ and saturation magnetization $M_{\mathrm{ s}}$ of the nanostructure significantly increased while the coercivity $H_{\mathrm {ci}}$ gradually decreased, and at $x = 7.25$ , a peak value of the maximum energy product $(BH)_{\mathrm {max}} = 19.7$ MGOe was obtained. The detailed mechanism was also discussed. [ABSTRACT FROM AUTHOR]

Cell sorting by filtration techniques offers a label-free approach for cell separation on the basis of size and deformability. However, filtration is always limited by the unpredictable variation of the filter hydrodynamic resistance due to cell accumulation and clogging in the microstructures. In this study, we present a new integrated microfluidic device for cell separation based on the cell size and deformability by combining the microstructure-constricted filtration and pneumatic microvalves. Using this device, the cell populations sorted by the microstructures can be easily released in real time for subsequent analysis. Moreover, the periodical sort and release of cells greatly avoided cell accumulation and clogging and improved the selectivity. Separation of cancer cells (MCF-7, MDA-MB-231 and MDA231-LM2) with different deformability showed that the mixture of the less flexible cells (MCF-7) and the flexible cells (MDA-MB-231 and MDA231-LM2) can be well separated with more than 75% purity. Moreover, the device can be used to separate cancer cells from the blood samples with more than 90% cell recovery and more than 80% purity. Compared with the current filtration methods, the device provides a new approach for cancer cell separation with high collection recovery and purity, and also, possesses practical potential to be applied as a sample preparation platform for fundamental studies and clinical applications. [ABSTRACT FROM AUTHOR]

Abstract: Integrity of the cell membrane is a basic requirement for maintaining the biological characteristics of a cell. In this study, changes in the morphology and ultrastructure of HeLa (human cervical carcinoma), HepG2 (human hepatocellular liver carcinoma), and C6 (rat glioma) cells were studied by atomic force microscopy (AFM) both before and after treatment with the anti-cancer drugs, colchicine or cytarabine. In response to both drugs, the microstructure of the cell membrane of all three cell types displayed similar changes; that is, with increases in drug concentration and reaction time, the degree of morphological changes on the surface of cell membrane increased. These changes included increases in the fluctuation of the surface components of the cell membrane, increase in shrinkage, or even the appearance of pores. Cell viability was maintained, as determined by optical microscope observation of gross cell morphology and by MTT assay results. Analysis of the cell membrane root-mean-square (RMS) roughness showed that under the action of colchicine and cytarabine, RMS values for the cell membranes of all three tumor cell types were positively correlated to the drug concentration and reaction time. This research has great significance for the visual diagnosis of early stage apoptosis in tumor cells in response to anti-cancer drugs, as well as in the studies on the interaction between drugs and cells. The use of AFM can be a rapid and sensitive visual method for studying the interaction between cells and drug. [Copyright &y& Elsevier]

Abstract: Rapid assessment of acute myocardial infarction (AMI) was successfully demonstrated using an improved superparamagnetic polymer microsphere-assisted sandwich fluoroimmunoassay to detect two early cardiac markers—myoglobin and human heart-type fatty acid binding protein (H-FABP). This assay used a preparation of superparamagnetic poly(styrene-divinylbenzene-acrylamide) microspheres, glutaraldehyde-coupled capture antibodies (monoclonal anti-myoglobin 7C3 and anti-H-FABP 10E1) grafted onto the polymer microspheres, and a sequential sandwich fluoroimmunoassay using detection antibodies (FITC-labeled anti-myoglobin 4E2 and FITC-labeled anti-H-FABP 9F3). Characterization of the polymer microspheres by TEM, SEM and Fourier transform infrared spectroscopy (FT-IR) showed that the microspheres were uniformly round with an average diameter of 1.12μm, and had a Fe3O4-polymer core–shell structure (shell thickness was about 84nm) with 0.22mmol/g amino groups on their surfaces. The magnetic behavior of the Fe3O4-polymer microspheres was superparamagnetic (M s =13emu/g, H c =13.1Oe). Fluorescence images of the post-immunoassay microspheres recorded using a confocal laser-scanning microscope showed that the average fluorescence intensity was correlated with the concentration of cardiac markers, in agreement with the results obtained by an F-4500 FL spectrophotometer; this indicated that the fluoroimmunoassay could be used to semi-quantitatively detect both myoglobin and H-FABP. The detection limit was 25ng/mL for myoglobin and 1ng/mL for H-FABP. [Copyright &y& Elsevier]

Microfluidic mixings create considerable opportunities for microscale exploration of biomacromolecule function and local reaction kinetics. However, a robust and efficient way for localized mixing performance is not yet well established. In this study, we describe a simple and reliable method for rapid, stable, and controllable in situ mixing using a single-layer acoustofluidic system with a microneedle. We developed the single microstructure for region-confined mixing, which can be controlled dynamically by intentional acoustic activation. Various acoustofluidic impacts including driving frequency, microstructure design, driving voltage, and flow control on homogeneous mixing were systematically investigated. The microneedle-based device allows a fast (∼ 85 ms) mixing operation. Robust and high reusability of acoustofluidic system was experimentally demonstrated with up to 200 times of repetitive mixing and 100 min of continuous mixing. Furthermore, the proof-of-concept applications including real-time characterization of fluorescein quenching and β -glucuronidase-catalyzed hydrolysis of 4-methyl-umbelliferyl- β - d -glucuronide were successfully accomplished in the in situ mixing platform. We believe this microfluidic system could be suitable for investigation of different instantaneous chemical/biochemical events associated with various molecular interactions and reactions. Also, the acoustofluidic approach is potentially valuable to the development of mixing-based integrated microfluidic systems for applications in molecular science and life science. [ABSTRACT FROM AUTHOR]

Eu 2+ /Eu 3+ -doped fluorophosphate Na 5 Al(PO 4 ) 2 F 2 was synthesized by the high-temperature solid-state reaction. The structural XRD refinement was used to investigate the phase formation and structure. The photoluminescence (PL) excitation and emission spectra were measured. The host accommodates two kinds of Eu-centers in the lattices, i.e., Eu 3+ and Eu 2+ , which were confirmed by the emission spectra and decay curves. Under the excitation of UV and near-UV light, the broad emission peaked at 420 nm and 530 nm from the 4 f 6 5 d –4 f 7 transition of Eu 2+ and narrow peaks at 592 nm, 615 nm from the 4 f –4 f transitions of Eu 3+ ions were detected. The luminescence color could shift from blue to white and red by mixing the luminescence from the coexistence of Eu 2+ /Eu 3+ ions in the single-phase phosphor. [ABSTRACT FROM AUTHOR]

• Bulk SmCo 3 magnet with (0 0 l) texture and nano grain size were prepared. • Bulk SmCo 3 magnet has an obvious magnetic anisotropy and 4.2 MGOe. • The energy product of anisotropic magnet is 120% larger than that of isotropic. • Bulk SmCo 3 magnet has potential for high-temperature applications. In bulk SmCo 3 nanocrystalline materials with small grain sizes of 10–20 nm, it is a challenge to realize a strong crystal texture that is crucial for them as high-performance permanent magnets. Here we fabricated an anisotropic bulk SmCo 3 nanocrystalline magnet with a strong (00 l) texture combined with a small grain size of 10–20 nm using a high-pressure thermal compression (HPTC) approach from amorphous precursors. This magnet had an obvious magnetic anisotropy with M r// / M r⊥ = 1.53 and a maximum energy product of 4.2 MGOe (33.8 kJ/m3) which were obviously higher than those M r// / M r⊥ = 1.01 and 1.9 MGOe (15.1 kJ/m3) of the isotropic magnets prepared using the same precursors. These anisotropic magnets showed a coercivity temperature coefficient of β = –0.31 %/°C and a remanence temperature coefficient of α = –0.14 %/°C. The deformation and annealing temperatures played important roles on the microstructures and magnetic properties of these anisotropic SmCo 3 nanocrystalline magnets. These findings make an important step toward the fabrication of oriented bulk SmCo 3 magnets for practical applications. [ABSTRACT FROM AUTHOR]