Strongly Charged Polymer Brushes

Charged polymer brushes are layers of surface-tethered chains. Experimental systems are frequently strongly charged. Here we calculate phase diagrams for such brushes in terms of salt concentration n_s, grafting density and polymer backbone charge density. Electrostatic stiffening and counterion condensation effects arise which are absent from weakly charged brushes. In various phases chains are locally or globally fully stretched and brush height H has unique scaling forms; at higher salt concentrations we find H ~ n_s^(-1/3), in good agreement with experiment.Comment: 5 pages, 3 Postscript figure

Bioactivity/cytotoxicity of micro-/nano-materials and novel development of fiber-optic probes for single cell monitoring

Manufactured nano-/micro-materials (MNMs) have been widely used and their interactions with niche biological environment are highly concerned for both of their biohazardous and bioactive effects, whereas no available comprehensive evaluations or regulations have been provided yet. This dissertation thus focuses on three major aspects: 1) fundamental toxicity understandings of a typical MNMs (zinc oxide nanoparticles), 2) bioactivity evaluations of representative bioactive MNMs, and 3) development of novel micro-probes for high spatial resolution monitoring. Firstly, the NP\u27s concentration, irradiation, hydrodynamic size, and the localized pH, ionic strength, NP zeta-potential as well as dissolved oxygen levels were found correlated with the production of hydroxyl radicals (•OH). Thus a novel physicochemical mechanism was hypothesized on •OH generation from ZnO NPs to cast light on cytotoxic mechanisms of MNMs. Secondly, silicate-/borate-based nano-/micro-sized glass fibers showed good rehabilitation capability and the underlying mechanisms were revealed as that quicker ion releasing and glass conversion (into hydroxyapatite (HA)) are the key to promote cell proliferation and migration, thus the wound-healing effect. Thirdly, several types of fiber-optic-based probes were developed to better cope with high spatial resolution, niche biological environmental detection. Up to date the best probe is able to acquire a pH resolution of up to ~0.02 pH unit within biologically relevant pH range of 6.17 - 8.11 with fast sensing time of ~5 seconds. Real-time monitoring of single live human cells were also demonstrated and validated in cytotoxic studies to detect early-onset of cell deterioration on different stages, indicating its powerful potent on studies that focusing on MNMs and single cells --Abstract, page iv

A Digital Watermarking Approach Based on DCT Domain Combining QR Code and Chaotic Theory

This paper proposes a robust watermarking approach based on Discrete Cosine Transform domain that combines Quick Response Code and chaotic system.Comment: 7 pages, 6 figure

Transport properties of single MgB2 filaments extracted from multifilamentary conductors

Using an electrochemical bath copper and nickel metals and alloys are removed in multifilamentary MgB2 conductors to leave single MgB2 filaments surrounded by a Nb sheath. Starting from a 0.55 mm 36 filament diameter conductor, the etched filaments are 60 microns in diameter. Seven wires were characterized by transport critical current measurement, and one investigated further by resistivity when progressively etched. Their radial location in the original multifilamentary wire structure is then used to explore if the critical current is sensitive to the deformation process. The average critical current of the outer layer of filaments is 35% higher than the inner layers. The average filament critical current was 32 A which is within 10 % of the 36 filament wire critical current per filament when adjusted for self field

Overexpression of DCF1 Inhibits Glioma through Destruction of Mitochondria and Activation of Apoptosis Pathway

Gliomas are the most common brain tumors affecting the central nervous system and are associated with a high mortality rate. DCF1 is a membrane protein that was previously found to play a role in neural stem cell differentiation. In the present study, we found that overexpression of dcf1 significantly inhibited cell proliferation, migration, and invasion and dramatically promoted apoptosis in the glioblastoma U251 cell line. DCF1 deletion mutations in the functional region showed that the complete structure of DCF1 was necessary for apoptosis. Furthermore, significantly lower tumorigenicity was observed in athymic nude mice by transplanting U251 cells overexpressing dcf1. To decode the apoptosis induced by dcf1, mitochondrial structure and membrane potential in glioma cells were investigated and the results indicated obvious mitochondrial swelling, destruction of cristae, and a significant decline in membrane potential. Mechanismly, caspase-3 signaling was activated. Finally, endogenous dcf1 silence in U251 cells was investigated. Results showed a highly methylation at -1339 and -1322 position at dcf1 promoter sequence, revealing the causal relationship between dcf1 gene and tumorigencicity. The present study identified a previously unknown cancer apoptosis mechanism involving dcf1 overexpression and provided a novel approach to potentially treat glioma patients

Fiber-Optic Micro-Probes for Measuring Acidity Level, Temperature, and Antigens

A pH micro-probe, a temperature micro-probe, and an immuno-based micro-probe each include a shaft for transmuting an input light signal and a tip for inserting into a cell or other substance for measuring pH, temperature, and/or antigens. The pH micro-probe and the temperature micro-probe each include a luminescent material positioned on the tip of the micro-probe. The light signal excites the luminescent material so that the luminescent material emits a luminescent light signal. The luminescent light signal has a property value dependent on the pH or temperature being measured and reflects back through the shaft for being measured by a light signal measuring device. The immuno-based micro-probe includes a reflective material that has an effective refractive index dependent on the number of antigen-antibody bonds present on the reflective material