Thrust chamber material technology program

This report covers work performed at Pratt & Whitney on development of copper-based materials for long-life, reusable, regeneratively cooled rocket engine thrust chambers. The program approached the goal of enhanced cyclic life through the application of rapid solidification to alloy development, to introduce fine dispersions to strengthen and stabilize the alloys at elevated temperatures. After screening of alloy systems, copper-based alloys containing Cr, Co, Hf, Ag, Ti, and Zr were processed by rapid-solidification atomization in bulk quantities. Those bulk alloys showing the most promise were characterized by tensile testing, thermal conductivity testing, and elevated-temperature, low-cycle fatigue (LFC) testing. Characterization indicated that Cu- 1.1 percent Hf exhibited the greatest potential as an improved-life thrust chamber material, exhibiting LCF life about four times that of NASA-Z. Other alloys (Cu- 0.6 percent Zr, and Cu- 0.6 percent Zr- 1.0 percent Cr) exhibited promise for use in this application, but needed more development work to balance properties

John Dewey\u27s Ideas About the Great Depression

Some criticisms that have been directed against John Dewey\u27s political theory reveal a general misunderstanding of his intent. Dewey was quite active in writing, lecturing, and propagandizing during the Depression years. Our primary concern in this article is the role he played in the efforts of the League for Independent Political Action to sponsor a third party from 1928 until the collapse of this project in 1936. Concurrent with this movement is Dewey\u27s work with the People\u27s Lobby in advocating social welfare programs to meet the crises generated by the Depression

Walter Kaufmann, Discovering the Mind: Goethe, Kant, and Hegel

Book review by Edward Bordeau: Kaufmann, Walter Arnold. Discovering the mind: Goethe, Kant, and Hegel. New York: McGraw Hill, 1980

BF Theories and Group-Level Duality

It is known that the partition function and correlators of the two-dimensional topological field theory $G_K(N)/ G_K(N)$ on the Riemann surface $\Sigma_{g,s}$ is given by Verlinde numbers, dim($V_{g,s,K}$) and that the large $K$ limit of dim($V_{g,s,K}$) gives Vol(${\cal M}_s$), the volume of the moduli space of flat connections of gauge group $G(N)$ on $\Sigma_{g,s}$, up to a power of $K$. Given this relationship, we complete the computation of Vol(${\cal M}_s$) using only algebraic results from conformal field theory. The group-level duality of $G(N)_K$ is used to show that if $G(N)$ is a classical group, then $\displaystyle \lim_{N\rightarrow \infty} G_K(N) / G_K(N)$ is a BF theory with gauge group $G(K)$. Therefore this limit computes Vol(${\cal M}^\prime_s$), the volume of the moduli space of flat connections of gauge group $G(K)$

Homogeneous redox catalysed reduction of chloromethyldimethylchlorosilane

The electrochemical reduction of chloromethyldimethylchlorosilane, affording 1,1,3,3-tetramethyl-1,3-disilacyclobutane, involves a dissociative electron transfer to the LUMO which contains the predominant contribution of the Si-Cl orbitals, and results in the C-Cl bond cleavage. The reduction of trimethylchlorosilane occurs through the dissociative Si-Cl bond rupture. In the course of the reduction of chloromethyltrimethylsilane, the α-silicon stabilisation of the negative charge makes an individual anion radical to appear on the reaction coordinate. © 1999 Elsevier Science Ltd. All rights reserved

Analysis of graft survival in a trial of stem cell transplant in ALS

Objective The first US Food and Drug Administration–approved clinical trial to treat amyotrophic lateral sclerosis ( ALS ) with neural stem cell–based therapy is in progress. The goal of the current study was to identify and assess the survival of human spinal cord–derived neural stem cells ( HSSC s) transplanted into the spinal cord in patients with ALS . Methods Spinal cords transplanted with HSSCs were examined from six autopsy cases. Homogenized tissues were interrogated for the presence of donor versus recipient DNA using real‐time PCR methods ( qPCR ). Fluorescence in situ hybridization (FISH) was performed using DNA probes for XY chromosomes to identify male donor HSSCs in one female case, and immunohistochemistry (IHC) was used to characterize the identified donor cells. Results Genomic DNA from donor HSSC s was identified in all cases, comprising 0.67–5.4% of total tissue DNA in patients surviving 196 to 921 days after transplantation. In the one female patient a “nest” of cells identified on H&E staining were XY ‐positive by FISH , confirming donor origin. A subset of XY ‐positive cells labeled for the neuronal marker NeuN and stem cell marker SOX 2. Interpretation This is the first study to identify human neural stem cells transplanted into a human spinal cord. Transplanted HSSC s survived up to 2.5 years posttransplant. Some cells differentiated into neurons, while others maintained their stem cell phenotype. This work is a proof of concept of the survival and differentiation of human stems cell transplanted into the spinal cord of ALS patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109593/1/acn3134.pd

Tetrakis(trimethylsilyloxy)silane for nanostructured SiO2-like films deposited by PECVD at atmospheric pressure

We performed the thin films deposition using atmospheric pressure plasma enhanced chemical vapour deposition (AP-PECVD) by means of a radiofrequency and a microwave plasma jets operating with mixtures of argon and tetrakis(trimethylsilyloxy)silane (TTMS)

Photocatalytic activity of nitrogen-doped TiO2-based nanowires: a photo-assisted Kelvin probe force microscopy study

The emerging industrial business partnerships, which feature cross-functional and cross-company development efforts, raise the barrier for the establishment of effective knowledge sharing practices in the larger organization. This chapter aims to highlight the role of knowledge as a key enabler for effective engineering activities in the light of such emerging enterprise collaboration models. Knowledge Enabled Engineering (KEE) is presented as an approach to enhance the extended organization’s capability to establish effective collaboration among its parts, in spite of different organizational structures, technologies or processes. KEE is analysed in its constituent parts, highlighting areas, methods and tools that are particularly interesting for leveraging companies’ knowledge sharing capabilities