No description available.

No description available.

No description available.

No description available.

A series of hydrophobic and hydrophilic self-assembled monolayers (SAMs) were deposited by the adsorption of 1- dodecanethiol (SAM I), 11-mercapto-1-undecanol (SAM II), 16- mercaptohexadecanoic acid (SAM III), 5-(10-mercaptodecyloxy) benzene-1,3-dioic acid (SAM IV) and 4-(10-mercaptodecyloxy)- pyridine-2,6-dicarboxylic acid (SAM V) on gold substrates. Crystallization experiments were carried out on SAMs I-V, on control surfaces (bulk gold, glass and PDMS (polydimethlysiloxane)) and in microfluidic devices to screen the polymorphs of two well known drugs, acetaminophen and barbital. Microfluidic devices consist of PDMS (polydimethlysiloxane) patterned with microchannels and then bonded to self-assembled monolayers (SAMs) of organic molecules on gold substrates. The crystallization of acetaminophen was carried out under thermodynamic conditions from solutions at room temperature and under kinetic conditions by rapid cooling. The results of crystallization experiments and the influence of self-assembled monolayers (SAMs) in controlling polymorphism by acting as nucleation sites, or templates, are discussed.

"Retinal prostheses are becoming a viable therapy for inner retinal degeneration caused by age related macular degeneration (AMD) and retinitis pigmentosa (RP). The majority of ocular and periocular prosthetic devices employ photodiodes and a microelectrode interface to convert light into a nerve impulse within the retina. Problems with this design include the need of an external power source, the lack of biocompatibility of the microelectrode array, and the need for complicated surgical procedures. Self-assembled monolayer (SAM) technology offers an alternative strategy, where neurons can be stimulated by light activation of a single layer of a photovoltaic SAM. We have developed a SAM structure where the photoexcitable dye 2-[2-[4-(dibutylamino)phenyl]ethenyl]-3-caboxymethylbenzothiazolium bromide (NK5962) was covalently immobilized to an indium tin oxide (ITO) and 3-(aminopropyl) trimethoxysilane (APTMS) surface. The NK562 derivatized surface was characterized through contact angle goniometry, electrochemical impedance spectroscopy, grazing angle infrared spectroscopy, and ultraviolet-visible absorption spectrophotometry. NG108-15 neurons were differentiated onto the surface and neural responses from electrical stimulation and photostimulation of the system were measured using whole-cell current and voltage clamp methodologies. We found an average 2.9 mV decrease in NG108-15 threshold potential for every 10 mV increase in ITO surface potential. Following photostimulation, there was a 1.8±0.2 fold increase (p < 0.05) in the sodium channel current amplitude and a 2.00 ± 0.22 fold increase (p < 0.05 ) in voltage amplitude of NG108-15 neurons on the ITO-APTMS-NK5962 surface due to transfer of energy from the excited dye surface to the attached neurons. The degree of photostimulation decreased upon using 344, 430, and 603 nm optical filters to block increasing amounts of the wavelengths of incident light capable of being absorbed by NK5962. The sodium current amplitude slightly increased at 50% transmittance of incident light relative to 100% transmittance, then sharply decreased at 12.5%, 6.25%, 3.13% transmittance. Upon addition of tetrodotoxin (TTX), sodium channel blockage was observed and portrayed by decreased sodium current and voltage response amplitudes, validating the voltage and current clamp results described above. Our findings indicate that the NK5962 photoelectric film shows promise as an implant for restoring light sensitivity to the retina. "

Thermoelectric materials can provide solutions to power generation and refrigeration challenges. Layered chalchogenides are of particular interest, with bismuth telluride and lead telluride being the most common compounds. Bismuth telluride is often used for room temperature applications, while its solid solutions with antimony or selenium as well as lead tellurides show better thermoelectric properties at elevated temperatures. Regrettably, the efficiency of the known thermoelectric materials is still low. Evidently, bringing thermoelectric energy harvesting to commercial viability is a materials challenge: How can we obtain materials with figure of merit above 3? This question drives the research community since the successes of nanoengineering in the 1990s. Nowadays, high-pressure technology is a promising frontier for making further advances in thermoelectric material performance. The main goal of this thesis is to understand the electronic and thermoelectric properties of selected materials using density functional theory and semi-classical Boltzmann transport theory. Bulk and monolayer CuSbS2 and CuSbSe2 are studied to clarify the role of the interlayer coupling for the thermoelectric properties. The calculated band gaps of the bulk compounds turn out to be in agreement with experiments and significantly higher than those of the monolayers, which thus show lower Seebeck coefficients. Since also the electrical conductivity is lower, the monolayers are characterised by lower power factors. Therefore, the interlayer coupling, even though it is weak, is found to be essential for the thermoelectric response. We study Cu (Sb,Bi)(S,Se)2 under hydrostatic pressure up to 8 GPa, considering the van der Waals interaction, as these compounds have layered structures. We find an indirect band gap that decreases monotonically with increasing hydrostatic pressure. Only CuBiS2 shows an indirect-indirect band gap transition around 3 GPa, leading to conduction band convergence with a concomitant 20% increase in the Seebeck co-efficient. This enhancement results from a complex interplay between multivalley and multiband effects as well as changes of the band effective masses. The variation of the electronic band structure of AB2Te4 (A = Pb, Sn and B = Bi, Sb) under hydrostatic pressure up to 8 GPa is analyzed in detail and its consequences for the material properties are explained.

Induced pluripotent stem (iPS) cells that possess embryonic stem (ES) cell-like properties are generated through the use of the Yamanaka transcription factors, OCT4, SOX2, KLF4, and MYC (OSKM). Advanced transgene delivery methods utilizing non-integrating viruses for transduction of target cells has provided new opportunities for regenerative medicine in humans and other species. We sought to use this technology to generate equine iPS cells to address challenges in equine regenerative medicine. Umbilical cord matrix mesenchymal stromal cells (MSC) were transduced with the non-integrating Sendai virus encoding for the OSKM transcription factors. The cells initially were cultured on mouse embryonic feeder cells supplemented with LIF (10 ng/mL) and FGF2 (4 ng/mL). Transduction generated 21 initial colonies. Of these, four survived beyond 20 passages. The transduced equine cells morphologically resembled ES cells and expressed cell surface antigens indicative of ES cells. Molecular evaluation revealed the cells maintained expression of endogenous OSKM while the exogenous OSK transgenes were extinguished, but MYC was maintained. The transduced equine cells did not express the ES marker NANOG, but did express the trophectoderm markers CDX2 and TFAP2A. Both OCT4 and CDX2 were colocalized to the nucleus. The transduced equine cells were termed equine induced trophoblast (iTr) cells. Culture of the iTr cell in suspension resulted in formation of blastocyst-like spheres rather than solid cell aggregates indicative of ES and iPS cells. The iTr cells were transitioned to a feeder free monolayer culture. Transformation of the iTr cells to the spherical arrangement stimulated expression of genes that mark differentiation of trophoblast cells and up-regulated 250 transcripts over the monolayer arrangement. The iTr monolayer arrangement up-regulated 50 transcripts compared to the spherical arrangement. The iTr spheres respond to BMP4, EGF, and FGF2 by phosphorylating signal transduction proteins. Addition of BMP4, EGF, or FGF2 in combined pairs was able to alter TFAP2A, NEU1, and SLC35A1 expression. The generation of iTr cells by transduction of the Yamanaka reprogramming factors is not unique to equine cells. However, this report marks the generation of the first equine trophoblast cell line capable of recapitulating early equine trophoblast development. The new iTr line could prove valuable in gaining greater understanding of equine trophectoderm development. / Ph. D.

none

Monolayers of amphiphilic molecules at interface provide a unique system for understanding the thermodynamic and rheological properties of quasi two-dimensional systems. They are also an excellent model accessible for studying cell membranes. The feature of longrange organization of molecular tilt azimuth in monolayers at the air/water interface is one of the most interesting findings over the past two decades, which leads to the formation rich and defined textures. By observing the changes in these textures, the transitions between tilted monolayer phases can be detected. We study the boojum and stripe textures formed in the liquid-condensed phase of pentadecanoic acid (PDA) monolayers at the air/water interface and find that they can be preserved after being transferred to glass substrates at low dipping speeds at a temperature lower than the room temperature. Frictional force microscopy confirms the long-range tilt order in the transferred boojums and stripes of PDA, implying the interaction of the PDA molecules with the glass surface does not change the tilt order. Polymerized stripe textures of pentacosadiynoic acid (PCA) monolayers can also be transferred onto solid substrates. Atomic force microscopy shows that the PCA stripe textures represent the regular variations of molecular packing densities in PCA monolayers. Furthermore, we find that the molecular orientation and packing density changes in monolayers can induce the local order of nematic liquid crystals. Due to the longrange orientation correlation of nematic liquid crystals, the boojum and stripe textures in monolayers can be observed by an optical microscope after liquid crystal optical amplification.