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A Preliminary Study on Using Multi-Nozzle Polymer Deposition System to Fabricate Composite Alginate/Carbon Nanotube Tissue Scaffolds
Three-dimensional composite alginate/single wall carbon nanotube (SWCNT) scaffolds
encapsulated with endothelial cells were fabricated by a multi-nozzle biopolymer freeform
deposition system. This system enables the converting of CAD designed scaffold pattern into
process toolpaths and the use of computer control program to guide the nozzle deposition at
spatial position for layered fabrication of 3D tissue scaffolds. The morphological, mechanical,
structural and biological properties of as-fabricated scaffolds were characterized by optical
microscope, SEM, Microtensile testing machine, Alamar Blue Assay, and Live-Dead Assay,
respectively. The multi-nozzle deposition system demonstrated a highly efficient and effective
process to build tissue scaffold or cell embedded constructs. Characterization results showed that
the incorporation of SWCNT into alginate not only enhanced the mechanical strength of the
scaffolds but also improved the cell affinity and the interaction with substrate. Further cell
culture experimental results also showed that the incorporation of SWCNT in alginate enhanced
endothelial cell proliferation compared with pure alginate scaffold.Mechanical Engineerin
Substrate effects on quasiparticles and excitons in graphene nanoflakes
The effects of substrate on electronic and optical properties of triangular
and hexagonal graphene nanoflakes with armchair edges are investigated by using
a configuration interaction approach beyond double excitation scheme. The
quasiparticle correction to the energy gap and exciton binding energy are found
to be dominated by the long-range Coulomb interactions and exhibit similar
dependence on the dielectric constant of the substrate, which leads to a
cancellation of their contributions to the optical gap. As a result, the
optical gaps are shown to be insensitive to the dielectric environment and
unexpectedly close to the single-particle gaps.Comment: 4 pages, 4 figure
Geochemistry of reduced inorganic sulfur, reactive iron, and organic carbon in fluvial and marine surface sediment in the Laizhou Bay region, China
Understanding the geochemical cycling of sulfur in sediments is important because it can have implications for both modern environments (e.g., deterioration of water quality) and interpretation of the ancient past (e.g., sediment C/S ratios can be used as indicators of palaeodepositional environment). This study investigates the geochemical characteristics of sulfur, iron, and organic carbon in fluvial and coastal surface sediments of the Laizhou Bay region, China. A total of 63 sediment samples were taken across the whole Laizhou Bay marine region and the 14 major tidal rivers draining into it. Acid volatile sulfur, chromium (II)-reducible sulfur and elemental sulfur, total organic carbon, and total nitrogen were present in higher concentrations in the fluvial sediment than in the marine sediment of Laizhou Bay. The composition of reduced inorganic sulfur in surface sediments was dominated by acid volatile sulfur and chromium (II)-reducible sulfur. In fluvial sediments, sulfate reduction and formation of reduced inorganic sulfur were controlled by TOC and reactive iron synchronously. High C/S ratios in the marine sediments indicate that the diagenetic processes in Laizhou Bay have been affected by rapid deposition of sediment from the Yellow River in recent decades
A simulation study of two major events in the heliosphere during the present sunspot cycle
The two major disturbances in the heliosphere during the present sunspot cycle, the event of June to August, 1982, and the event of April to June, 1978, are simulated by the method developed by Hakamada and Akasofu (1982). Specifically, an attempt was made to simulate the effects of six major flares from three active regions in June and July, 1982, and April and May, 1978. A comparison of the results with the solar wind observations at Pioneer 12 (approximately 0.8 au), ISEE-3 (approximately 1 au), Pioneer 11 (approximately 7 to 13 au) and Pioneer 10 (approximately 16 to 28 au) suggests that some major flares occurred behind the disk of the sun during the two periods. The method provides qualitatively some information as to how such a series of intense solar flares can greatly disturb both the inner and outer heliospheres. A long lasting effect on cosmic rays is discussed in conjunction with the disturbed heliosphere
Temperature- and Bias-dependence of magnetoresistance in doped manganite thin film trilayer junctions
Thin film trilayer junction of LaSrMnO - SrTiO -
LaSrMnO shows a factor of 9.7 change in resistance, in a
magnetic field around 100 Oe at 14K. The junction magnetoresistance is bias and
temperature dependent. The energy scales associated with bias and temperature
dependence are an order of magnitude apart. The same set of energies also
determine the bias and temperature dependence of the differential conductance
of the junction. We discuss these results in terms of metallic cluster
inclusions at the junction-barrier interface.Comment: 3 pages, 4 figure
Pressure study of nematicity and quantum criticality in SrRuO for an in-plane field
We study the relationship between the nematic phases of SrRuO and
quantum criticality. At ambient pressure, one nematic phase is associated with
a metamagnetic quantum critical end point (QCEP) when the applied magnetic
field is near the \textit{c}-axis. We show, however, that this metamagnetic
transition does not produce the same nematic signatures when the QCEP is
reached by hydrostatic pressure with the field applied in the
\textit{ab}-plane. Moreover, a second nematic phase, that is seen for field
applied in the \textit{ab}-plane close to, but not right at, a second
metamagnetic anomaly, persists with minimal change to the highest applied
pressure, 16.55 kbar. Taken together our results suggest that metamagnetic
quantum criticality may not be necessary for the formation of a nematic phase
in SrRuO
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