Browsing by Author "Zhang, Chen"
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- An ECA-Based ZigBee ReceiverZhang, Chen (Virginia Tech, 2008-02-01)Element CXI's Elemental Computing Array (ECA) delivers faster reconfiguration time and higher computational density than Field Programmable Gate Arrays (FPGAs) with similar computational power. It provides higher computational power than Digital Signal Processors (DSPs) with similar power consumption and price. It also utilizes a library-based graphical development environment promoting ease of use and fast development. In this thesis, the design and implementation of a ZigBee receiver on an Element CXI ECA-64 platform is presented. The ZigBee receiver is evaluated through simulations and implementation on an ECA device. During the design and implementation of the ZigBee receiver, some design experience and tips are concluded. The design methodology on the ECA is studied in detail to assure the implementation's correctness, since the methodology of the ECA is different from that of other platforms.
- Extract Methods, Molecular Characteristics, and Bioactivities of Polysaccharide from Alfalfa (Medicago sativa L.)Zhang, Chen; Li, Zemin; Zhang, Chong-Yu; Li, Mengmeng; Lee, Yunkyoung; Zhang, Gui-Guo (MDPI, 2019-05-27)The polysaccharide isolated from alfalfa was considered to be a kind of macromolecule with some biological activities; however, its molecular structure and effects on immune cells are still unclear. The objectives of this study were to explore the extraction and purifying methods of alfalfa (Medicago sativa L.) polysaccharide (APS) and decipher its composition and molecular characteristics, as well as its activation to lymphocytes. The crude polysaccharides isolated from alfalfa by water extraction and alcohol precipitation methods were purified by semipermeable membrane dialysis. Five batches of alfalfa samples were obtained from five farms (one composite sample per farm) and three replicates were conducted for each sample in determination. The results from ion chromatography (IC) analysis showed that the APS was composed of fucose, arabinose, galactose, glucose, xylose, mannose, galactose, galacturonic acid (GalA), and glucuronic acid (GlcA) with a molar ratio of 2.6:8.0:4.7:21.3:3.2:1.0:74.2:14.9. The weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of APS were calculated to be 3.30 × 106, 4.06 × 105, and 1.43 × 108 g/mol, respectively, according to the analysis by gel permeation chromatography-refractive index-multiangle laser light scattering (GPC-RI-MALS). The findings of electron ionization mass spectrometry (EI-MS) suggest that APS consists of seven linkage residues, namely 1,5-Araf, galactose (T-D-Glc), glucose (T-D-Gal), 1,4-Gal-Ac, 1,4-Glc, 1,6-Gal, and 1,3,4-GalA, with molar proportions of 10.30%, 4.02%, 10.28%, 52.29%, 17.02%, 3.52%, and 2.57%, respectively. Additionally, APS markedly increased B-cell proliferation and IgM secretion in a dose- and time-dependent manner but not the proliferation and cytokine (IL-2, -4, and IFN-γ) expression of T cells. Taken together, the present results suggest that APS are macromolecular polymers with a molar mass (indicated by Mw) of 3.3 × 106 g/mol and may be a potential candidate as an immunopotentiating pharmaceutical agent or functional food.