Search

Progress in the development of a new class of multi-functional polyimides for use in electro-optical devices is reported. These polyimides contain hydroxymethyl-functional side-groups attached to the polymer backbone, allowing for the attachment of a wide variety of molecular species. It is shown that multiple types of organic molecules may be attached to the polymer simultaneously, with a quantitatively controllable distribution, to tailor the physical properties of the material. Methods for cross-linking the polyimides are presented, based on both modification to the backbone and the addition of difunctional additives (such as isocyanates) to solutions of the polymer during spin casting. Processing studies using spectroscopy to track the cross-linking reaction and its effects on organic nonlinear optical materials indicate that the latter method is compatible with poling processes for polymer guest/host systems with high nonlinear optical activities. Further studies using a novel thermomechanical analysis method demonstrate that the cross-linking reactions increase the glass transition temperature and inhibit physical relaxation processes in the cross-linked guest/host films.

Mach-Zehnder optical modulators were fabricated using the CLD and FTC chromophores in polymer-on-silicon optical waveguides. Up to 17 months of oven-ageing stability are reported for the poled polymer films. Modulators containing an FTC-polyimide had the best over all aging performance. To model and extrapolate the ageing data, a relaxation correlation function attributed to A. K. Jonscher was compared to the well-established stretched exponential correlation function. Both models gave a good fit to the data. The Jonscher model predicted a slower relaxation rate in the out years. Analysis showed that collecting data for a longer period relative to the relaxation time was more important for generating useful predictions than the precision with which individual model parameters could be estimated. Thus from a practical standpoint, time-temperature superposition must be assumed in order to generate meaningful predictions. For this purpose, Arrhenius-type expressions were found to relate the model time constants to the ageing temperatures.

The forebody aerothermodynamic environment for the Genesis Sample Return Capsule (SRC) is analyzed at different trajectory points along a Best Estimated Trajectory (BET). Laminar and turbulent calculations are computed for the Genesis heatshield with and without circular penetrations in the carbon-carbon thermal protection system material. In addition, surface heating effects of using molybdenum penetrations on a carbon-carbon heatshield are investigated. These simulations show that differential surface catalycity has a small influence on the aerothermal environment while a transition from laminar to turbulent flow can increase the surface heating by a factor of two to three times the laminar values. The presence of forebody penetrations may also hasten the flow to transition from laminar to turbulence earlier in the trajectory, which would result in higher heating downstream of these cavities.

We have developed a novel androgen receptor (AR) expression system in the 293 human embryonic kidney cell line that recapitulates AR biochemical activity as a steroid hormone receptor in prostate cancer cells. We used this system to identify putative AR-binding proteins in the cytosolic and nuclear compartments of mammalian cells using a large scale co-immunoprecipitation strategy coupled to quantitative mass spectrometry. For example, the heat shock 70 and 90 chaperones, which are known regulators of steroid hormone receptor, were identified as AR-binding proteins. AR purification enriched for proteins involved in RNA processing, protein transport, and cytoskeletal organization, suggesting a functional link between AR and these protein modules in mammalian cells. For example, AR purification in the nuclear compartment led to the specific enrichment of alpha-actinin-4, clathrin heavy chain, and serine-threonine protein kinase C delta. Short interfering RNA knockdown studies and co-transcriptional reporter assays revealed that clathrin heavy chain possessed co-activator activity during AR-mediated transcription, whereas alpha-actinin-4 and protein kinase C delta displayed both co-activator and co-repressor activity during AR-mediated transcription that was dependent upon their relative expression levels. Lastly immunohistochemical staining of prostate tissue showed that alpha-actinin-4 levels decreased in the nucleus of high grade cancerous prostate samples, suggesting its possible deregulation in advanced prostate cancers as previously observed in late stage metastatic breast cancers. Taken together, these findings suggest AR binds to specific protein modules in mammalian cells and that these protein modules may provide a molecular framework for interrogating AR function in normal and cancerous prostate epithelial cells.

A method of chemical synthesis that allows for the facile attachment of a wide variety of chemical compounds, including highly active nonlinear optical chromophores, to polyimides has been developed recently at the Naval Air Warfare Center, Weapons Division. The synthesis of these compounds is presented, along with a discussion of their relevant physical and chemical properties, alone and in comparison to equivalent guest/host materials. Examples of attached chromophores include the well-known Disperse Red 1, along with high-activity chromophores of more recent interest such as FTC and CLD. The synthesis of structures that contain both attached chromophores and chemical functionalities that enable thermal cross-linking of the polyimides is also discussed.

A series of oligomers consisting of ethynyl-linked azobenzene units was prepared using Pd-catalyzed cross coupling. The linear and nonlinear optical properties of the oligomers were investigated. The molecular second hyperpolarizability, gamma, followed the power law gamma proportional, variant n(2.12+/-0.05) (n is the number of repeat units) for unusually large molecular lengths exceeding 360 conjugated bonds (49 nm). The exceptional exciton delocalization length is attributed to the rigidity of the conjugated backbone.

This paper demonstrates a Monte Carlo analysis technique to establish margins on sizing a thermal protection system and identifies the chief sources of uncertainty in the material response modeling. Monte Carlo sensitivity and uncertainty studies are performed for the thermal protection systems of the Stardust Sample Return Capsule, Mars Exploration Rovers, and X-37 wing leading edge, using the Fully Implicit Ablation and Thermal response code. The computation results are presented and discussed in detail. It shows that a Monte Carlo approach provides more insight than the traditional Root-Sum-Square method into the relationship between the thickness margin of a thermal protection system and the probability of maintaining the temperature of the underlying material within specified requirements. Nomenclature erfi = inverse error function N = total number of samples R = random number x = input parameters y = output of interests σ = standard deviation * σ = mean x

An instrumented aircraft and ground-based observing campaign was mounted to measure the radiation from the hypervelocity (11.0 km/s) reentry of the Genesis Sample Return Capsule prior to landing on the Utah Test and Training Range on September 08, 2004. The goal was to validate predictions of surface heating, the physical conditions in the shock layer, and the amount and nature of gaseous and solid ablation products as a function of altitude. This was the first hypervelocity reentry of a NASA spacecraft since the Apollo era. Estimates of anticipated emissions were made. Erroneous pointing instructions prevented us from acquiring spectroscopic data, but staring instruments measured broadband photometric and acoustic information. A surface-averaged brightness temperature was derived as a function of altitude. From this, we conclude that the observed optical emissions were consistent with most of the emitted light originating from a gray body continuum, but with a surface averaged temperature of 570 K less than our estimate from the predicted heat flux. Also, the surface remained warm longer than expected. We surmise that this is on account of conduction into the heat shield material, ablative cooling, and finite-rate wall catalycity. Preparations are underway to observe a second hypervelocity reentry (12.8 km/s) when the Stardust Sample Return Capsule returns to land at U.T.T.R. on January 15, 2006.

Hypersonic vehicles experience different flow regimes during flight due to changes in atmospheric density. Hybrid Computational Fluid Dynamics (CFD) and direct simulation Monte Carlo (DSMC) methods are being developed to simulate the flow in different hypersonic regimes. These methods use a breakdown parameter to determine regions of the flow where the CFD physics are no longer valid. The current study investigates the effect of continuum breakdown on surface aerothermodynamic properties, such as pressure, shear stress and heat transfer rate, of a cylinder in a Mach 10 flow of argon gas for several different flow regimes, from the continuum to a rarefied gas. CFD and DSMC solutions are obtained at each flow condition. Total drag predictions are identical for a continuum flow while differing by more than 26% for a rarefied flow. Peak heat transfer rate differences range from less than 1% for a continuum flow to almost 32% for a rarefied flow. Drag depends primarily on continuum breakdown in the wake, while heat transfer rate appears to depend primarily on continuum breakdown in the shock and differences in thermal boundary layer thickness.

The maturation of MS technologies has provided a rich opportunity to interrogate protein expression patterns in normal and disease states by applying expression protein profiling methods. Major goals of this research strategy include the identification of protein biomarkers that demarcate normal and disease populations, and the identification of therapeutic biomarkers for the treatment of diseases such as cancer (Celis, J. E., and Gromov, P. (2003) Proteomics in translational cancer research: Toward an integrated approach. Cancer Cell 3, 9-151). Prostate cancer is one disease that would greatly benefit from implementing MS-based expression profiling methods because of the need to stratify the disease based on molecular markers. In this review, we will summarize the current MS-based methods to identify and validate biomarkers in human prostate cancer. Lastly, we propose a reverse proteomic approach implementing a quantitative MS research strategy to identify and quantify biomarkers implicated in prostate cancer development. With this approach, the absolute levels of prostate cancer biomarkers will be identified and quantified in normal and diseased samples by measuring the levels of native peptide biomarkers in relation to a chemically identical but isotopically labeled reference peptide. Ultimately, a centralized prostate cancer peptide biomarker expression database could function as a repository for the identification, quantification, and validation of protein biomarker(s) during prostate cancer progression in men.

An investigation of transitional/turbulent heating on the Mars Science Laboratory entry vehicle has been conducted. Laminar, transitional, and turbulent heating data were obtained in a perfect-gas, Mach 6 air wind tunnel and in a high-enthalpy shock tunnel in CO2. Flow field solutions were computed using a Navier-Stokes solver at the test conditions and comparisons were made between measured and predicted heating levels. Close agreement was obtained for all laminar perfect-gas cases. For the high-enthalpy CO2 cases, close agreement with the data was achieved when a fully-catalytic wall boundary condition was employed, whereas the predictions exceeded the data by more than 25% if a noncatalytic boundary condition was used. Turbulent heating predictions fell below the perfectgas air data by 25% but exceeded the CO2 data by 60%. Transition onset locations were determined through comparisons with laminar heating predictions, and boundary-layer parameters from the flow field solutions were used to develop correlations for the transition onset location and the turbulent heating augmentation on the leeside of the vehicle.

Assessment of nonequilibrium thermochemical models for shock layer radiation in N2/CH4 mixtures is presented via comparisons with spectrally and temporally resolved intensity measurements from a set of shock tube experiments. The experiments were carried out at the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center in a rarified environment [13.3-133.3 Pa (0.1 and 1 Torr)] representative of the peak heating conditions of a Titan aerocapture trajectory (5-9 km/s). The baseline model that assumes a Boltzmann population of the CN excited states consistently overpredicts the shock layer radiation intensity. A non-local collisional radiative model that solves a simplified master equation and includes radiative transport and non-local absorption in the shock tube is presented. The proposed model improves the prediction of the nonequilibrium radiation overshoot peak, but still underpredicts the intensity decay rate in the low pressure case. Further analysis suggests possible reasons for the remaining disagreement, the most likely being a slow CN consumption in the current chemical kinetics model in the intensity fall-off region.

A Monte Carlo uncertainty and sensitivity analysis technique is presented to i) identify the major sources of uncertainty in the thermochemical models used for aerothermal analysis, and ii) track the propagation of these uncertainties through the system into the predicted quantities of interest, such as the vehicle heating, shock layer properties, etc. The technique is applied to the aerothermal analysis of Titan aerocapture, where CN shock layer radiation is the dominant source of vehicle heating. Several hundred model input parameters, including reaction rate constants, vibration-chemistry coupling parameters, vibrational relaxation times, and transport properties, are independently sampled over their range of uncertainties, and the vehicle heating is determined probabilistically. A massively parallel, axisymmetric CFD (Data-Parallel Line Relaxation) code was used to make the several thousand runs needed to statistically describe the variability in the heating predictions. It is found that major contributions to the uncertainty in the predicted heating originates from the uncertainties in the rates of N2 dissociation by H atom impact, and some atomic exchange reactions: N2+H→NH+N and N2+C→CN+N.

Prostate cancer is unusual among neoplasms in that it may be diagnosed at a curable stage through detection of a protein in serum, the serine protease prostate-specific antigen (PSA). PSA is secreted by both normal and neoplastic prostate epithelial cells in response to androgenic hormones and has found widespread use in cancer screening. Because PSA screening is controversial due to sensitivity and specificity issues, efforts continue to focus on the identification and characterization of additional markers that may be used for diagnostic and therapeutic purposes. In this study, we report the application of quantitative proteomic techniques that incorporate isotope coded affinity tag reagents and tandem mass spectrometry to comprehensively identify secreted and cell surface proteins from neoplastic prostate epithelium. LNCaP cells, a prostate tumor-derived cell line that secretes PSA in response to androgen exposure, were grown in a low protein-defined media under androgen-stimulated (A+) and -starved (A-) conditions. Proteomic analysis of the media identified in excess of 600 proteins, 524 of which could be quantified. Nine percent of the proteins had A+/A- ratios > 2.0, including PSA, and 2.5% had ratios < 0.5. A subset of these androgen-regulated proteins appeared to be expressed in abundance. Of these, selected mass spectrometry observations were confirmed by Western analysis. The findings suggest that androgen-mediated release of proteins may occur through the activation of proteolytic enzymes rather than exclusively through transcriptional or translational control mechanisms. On the basis of their known functional roles, several of the abundant androgen-regulated proteins may participate in the progression of neoplastic epithelial cell growth and should be considered as potential serum markers of neoplastic prostate diseases.

Comprehensive understanding of biological systems requires efficient and systematic assimilation of high-throughput datasets in the context of the existing knowledge base. A major limitation in the field of proteomics is the lack of an appropriate software platform that can synthesize a large number of experimental datasets in the context of the existing knowledge base. Here, we describe a software platform, termed PROTEOME-3D, that utilizes three essential features for systematic analysis of proteomics data: creation of a scalable, queryable, customized database for identified proteins from published literature; graphical tools for displaying proteome landscapes and trends from multiple large-scale experiments; and interactive data analysis that facilitates identification of crucial networks and pathways. Thus, PROTEOME-3D offers a standardized platform to analyze high-throughput experimental datasets for the identification of crucial players in co-regulated pathways and cellular processes.

A large-scale proteomic approach has been used to define cellular processes that are responsive to androgen treatment in LNCaP prostate cancer cells. The results provide evidence for the role of androgenic hormones in coordinating the expression of critical components involved in distinct cellular processes, Background Androgens play a critical role in the development of prostate cancer-dysregulation of androgen-regulated growth pathways can led to hormone-refractory prostate cancer. A comprehensive understanding of androgen-regulated cellular processes has not been achieved to date. To this end, we have applied a large-scale proteomic approach to define cellular processes that are responsive to androgen treatment in LNCaP prostate cancer cells. Results Using isotope-coded affinity tags and mass spectrometry we identified and quantified the relative abundance levels of 1,064 proteins and found that distinct cellular processes were coregulated by androgen while others were essentially unaffected. Subsequent pharmacological perturbation of the cellular process for energy generation confirmed that androgen starvation had a profound effect on this pathway. Conclusions Our results provide evidence for the role of androgenic hormones in coordinating the expression of critical components involved in distinct cellular processes and further establish a foundation for the comprehensive reconstruction of androgen-regulated protein networks and pathways in prostate cancer cells.

Using coimmunoprecipitation and tandem mass spectrometry, we identify INSIG-1 as an ER protein that binds the sterol-sensing domain of SREBP cleavage-activating protein (SCAP) and facilitates retention of the SCAP/SREBP complex in the ER. In sterol-depleted cells, SCAP escorts SREBPs from ER to Golgi for proteolytic processing, thereby allowing SREBPs to stimulate cholesterol synthesis. Sterols induce binding of SCAP to INSIG-1, as determined by blue native-PAGE, and this is correlated with the inhibition of SCAP exit from the ER. Overexpression of INSIG-1 increases the sensitivity of cells to sterol-mediated inhibition of SREBP processing. Mutant SCAP(Y298C) fails to bind INSIG-1 and is resistant to sterol-mediated inhibition of ER exit. By facilitating sterol-dependent ER retention of SCAP, INSIG-1 plays a central role in cholesterol homeostasis.

In the pursuit of new photonic devices, the unique waveguide properties of chiral films made from single-handed helical molecules are under investigation. The synthesis of polymers with a hierarchical structure is the first step. In this paper we present results on the synthesis and characterization of poly(p-phenylenes) (PPPs) and polythiophenes possessing amine and amide chiral side-chains. A regioirregular PPP possessing one chiral side group per repeat unit was prepared. Regioregular PPPs possessing two chiral side groups per repeat unit were also synthesized; however, lower molecular weights were achieved due to steric constraints. The PPPs exhibited total optical rotation that was a function of the concentration of the chiral side group, with 35- per chiral group or 70- per repeat unit. A regioirregular polythiophene was prepared using oxidative polymerization. A molecular structure that leads to helical polymer chains that undergo supramolecular packing in spin-cast films is the goal.

The androgen receptor (AR) is a member of the nuclear receptor superfamily and the key transcription factor of androgen-mediated signaling pathways. AR translocates to the nucleus in response to ligand binding, where it selectively binds canonical androgen response elements (AREs) in DNA to assemble transcriptional complexes at target genes. Aberrant AR signaling resulting from unbalanced AR transcriptional responses at genes involved in cellular proliferation and differentiation drives the development and progression of human prostate cancers. In addition, the AR coregulator proteins, members of a large family that bind AR and modulate AR transcriptional activity, are known to elicit aberrant AR activity in prostate cancers. Although numerous AR coregulators have been identified, in most cases this was through static, binary protein-protein interaction assays (e.g., GST-fusion, yeast two-hybrid assays). Thus, to what degree androgen-sensitive coregulators mediate pathological AR actions in the context of human prostate cancer remains poorly defined. We have devised a biochemical strategy to identify and quantify androgen-sensitive coregulators (coactivators and corepressors) of AR-mediated transcription, based on their in vitro affinity for a model androgen-regulated gene promoter. Specifically, we have used DNA-affinity purification techniques in combination with label-free quantitative mass spectrometry (qMS) to do so. Our preliminary findings show that androgen-sensitive coregulators represent a functionally diverse group of protein involved in a number of signal transduction pathways. Furthermore, future studies utilizing selected reaction monitoring (SRM), a quantitative proteomics method, will be exploited to study the molecular functions of androgen-sensitive coregulators and facilitate the construction of quantitative models of AR-mediated transcription that will make it possible to predict androgenic responses at disease-associated, androgen-regulated genes. Our findings will broadly benefit the biomedical research community in that they define a novel class of androgen-sensitive coregulators and determine how they influence AR-mediated transcriptional processes underlying the development and progression of human prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C9.

Reaction of (MeCN)3Cr(CO)3 with hydroquinone in refluxing tetrahydrofuran (THF) produced {η6-1,4-C6H4(OH)2}Cr(CO)3 (1) which was subsequently converted to {η6-1,4-(CH3SO3)2C6H4}Cr(CO)3 (2) by treatment with methanesulfonyl chloride and triethylamine. A single-crystal X-ray study of 2 has been completed and is reported. Treatment of 2 with an oxygen nucleophile gave reaction at sulfur; whereas, treatment of 2 with lithium phenylacetylide resulted in decomposition of the complex to metallic chromium.

A crucial aim upon the completion of the human genome is the verification and functional annotation of all predicted genes and their protein products. Here we describe the mapping of peptides derived from accurate interpretations of protein tandem mass spectrometry (MS) data to eukaryotic genomes and the generation of an expandable resource for integration of data from many diverse proteomics experiments. Furthermore, we demonstrate that peptide identifications obtained from high-throughput proteomics can be integrated on a large scale with the human genome. This resource could serve as an expandable repository for MS-derived proteome information.

Background: Androgens play a critical role in the development of prostate cancer-dysregulation of androgen-regulated growth pathways can led to hormone-refractory prostate cancer. A comprehensive understanding of androgen-regulated cellular processes has not been achieved to date. To this end, we have applied a large-scale proteomic approach to define cellular processes that are responsive to androgen treatment in LNCaP prostate cancer cells. Results: Using isotope-coded affinity tags and mass spectrometry we identified and quantified the relative abundance levels of 1,064 proteins and found that distinct cellular processes were coregulated by androgen while others were essentially unaffected. Subsequent pharmacological perturbation of the cellular process for energy generation confirmed that androgen starvation had a profound effect on this pathway. Conclusions: Our results provide evidence for the role of androgenic hormones in coordinating the expression of critical components involved in distinct cellular processes and further establish a foundation for the comprehensive reconstruction of androgen-regulated protein networks and pathways in prostate cancer cells.

Monomer {η 5 -C 5 H 4 CH 2 OCOC(CH 3 )=CH}{η 5 -C 5 H 4 CH=C(CN)COOEt}Fe was prepared and radical copolymerized with methyl methacrylate. Second harmonic generation measurements for the copolymer film gave a value for d of 1.72pm/V

The new complex Fp(η1-C5H4CH3) (2) was prepared and its fluxionality studied. Complex 2 was found to have a higher energy barrier for the fluxional process than the related systems Fp(η1-C5H5), η5-C5Me5Fe(CO)2(η1-C5H5), and Fp(η1-C5H4CONHTs) (3). Reaction of 2 with dimethyl acetylenedicarboxylate gave a mixture of two cycloadducts where the methyl-group was found in the 5- and the 1-position in a ratio of 3 1 , respectively. In both cycloadducts the Fp moiety was found regio- and stereoselectively in the 7-position and anti to the carboxylate groups. The molecular structure of crystalline 3 was determined and showed that the CONHTs substituent of the η1-ring was in the 1-position.

Experimental evidence that the dinuclear complex Me 2 Si[η 5 -C 5 H 4 Fe(CO) 2 -(η 1 -CH 2 C 6 H 5 )] 2 shows enhanced reactivity over its mononuclear analogy η 5 -C 5 H 5 Fe(CO) 2 (η 1 -CH 2 C 6 H 5 in photogragmentation to produce bibenzyl and FeFe bonded product is presented. Information from a series of competition and crossover experiments indicate that two factors are involved in the enhancement: (1) the ability to photochemically produce a 16-electron unsaturated benzyl unit in close proximity to a saturated partner, and (2) the inability of the FeFe bonded species 4 to quench free benzyl radicals in solution. Chemical reaction of Me 2 Si[η 5 -C 5 H 4 Fe(CO) 2 (η 1 -CH 2 C 6 H 5 )] 2 with Me 3 NO produces bibenzyl and establishes that loss of CO is the initial step in the fragmentation reaction. In addition, trapping experiments with 9,10-dihydroanthracene show that bibenzyl is formed from free benzyl radical; BBased on these results an overall mechanism is proposed.