125 research outputs found
Low stress polysilicon film and method for producing same
Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin film may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films
Hodge-Tate stacks and non-abelian -adic Hodge theory of v-perfect complexes on rigid spaces
Let be a quasi-compact quasi-separated -adic formal scheme that is
smooth either over a perfectoid -algebra or over some ring of
integers of a complete discretely valued extension of with
-finite residue field. We construct a fully faithful functor from perfect
complexes on the Hodge-Tate stack of up to isogeny to perfect complexes on
the v-site of the generic fibre of . Moreover, we describe perfect complexes
on the Hodge-Tate stack in terms of certain derived categories of Higgs, resp.
Higgs-Sen modules. This leads to a derived -adic Simpson functor. We deduce
new results about the -adic Simpson correspondence in both cases
The small -adic Simpson correspondence in terms of moduli spaces
For any rigid space over a perfectoid extension of that admits
a liftable smooth formal model, we construct an isomorphism between the moduli
stacks of Hitchin-small Higgs bundles and Hitchin-small v-vector bundles. This
constitutes a moduli-theoretic improvement of the small -adic Simpson
correspondence of Faltings, Abbes-Gros, Tsuji and Wang. Our construction is
based on the Hodge-Tate stack of Bhatt-Lurie. We also prove an analogous
correspondence in the arithmetic setting of rigid spaces of good reduction over
-adic fields.Comment: revised version of what used to be the second part of
arXiv:2302.1274
Large area polysilicon films with predetermined stress characteristics and method for producing same
Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations
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Automated Fabrication ofCeramic Components from Tape-Cast Ceramic
This paper describes a machine and process for automated fabrication of functional 3-D
laminated engineering components, ceramics in the present example. A laser cuts successive layers
of a part derived from a CAD model description out of unfired tape-cast ceramic sheets
vacuum-clamped to an x-y sled. A material-handling robot uses a selective-area gripper to extract
only the desired part outlines from the surrounding waste material, then stacks the slices to build the
part. This system design enables rapid manufacture of functional engineering components with
arbitrarily complex internal and external geometries from virtually any material available in sheet
form.Mechanical Engineerin
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Low Temperature Surface Carburization of Stainless Steels
Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys • Thermodynamic modeling to explain the high degree of carbon solubility possible in austenitic grades under the LTCSS process and experimental validation of model results • Corrosion testing to determine the corrosion resistance improvement possible from the LTCSS process • Erosion testing to determine the erosion resistance improvement possible from the LTCSS process • Wear testing to quantify the wear resistance improvement possible from the LTCSS process • Fatigue testing for quantifying the extent of improvement from the LTCSS process • Component treating and testing under simulated and in-line commercial operations XRD verified expanded austenite lattice, with no evidence of carbide precipitation. Carbon concentration profiles via Auger and electron dispersion spectroscopy (EDS) showed carbon levels in excess of 12 at. % in treated, type 316 SS. Scanning electron microscopy (SEM) of pulled-to-failure treated tensile specimens showed slip bands and no de-cohesion of the treated layer, verifying that the layer remains ductile. Compressive stresses in excess of 2 GPa (300 ksi) have been calculated at the surface of the case. Phase diagram (CALPHAD) (ThermoCalc) and Wagner dilute solution thermodynamic models were developed that calculate the solubility of carbon in austenite as a function of alloying content for the process time and temperature. Several commercial alloys have been modeled, and the model has been used to design experimental alloys with enhanced affinity for carbon solubility at treatment temperatures. Four experimental alloys were melted, rolled, and manufactured into test specimens, and the LTCSS treatment indicated successfully enhanced results and validated the predictions based on thermodynamic modeling. Electrochemical polarization curves show a 600 to 800 mV increase in pitting potential in treated (900-1000 mV) versus non-treated (200-300 mV) type 316 in chloride solutions. Treated 316L showed crevice-corrosion behavior similar to that of Ti-6Al-4V and Hastelloy C22. Cavitation tests showed significant increases in cavitation resistance for treated materials as compared to the non-treated materials. Standard ASTM pin-on-disk sliding friction and reciprocating friction wear tests also indicate significant enhancement in wear properties. Fatigue testing showed an order of magnitude improvement for treated versus non-treated Type 316 at the same maximum stress level (R = -1). The maximum stress at 107 cycles and the endurance stress for infinite life, improved by approximately 50%, from 30 to 45 ksi. The energy savings from this project is estimated at 21.8 trillion Btu/year by 2020. This energy savings will be associated with a CO2 reduction of 1.3 million ton/year. One application of this technology in a sludge pump of a cardboard recycling plant during the course of this project has resulted in an energy savings of 84 106 Btu and cost savings of $900
Expression of Distal-less, dachshund, and optomotor blind in Neanthes arenaceodentata (Annelida, Nereididae) does not support homology of appendage-forming mechanisms across the Bilateria
The similarity in the genetic regulation of
arthropod and vertebrate appendage formation has been
interpreted as the product of a plesiomorphic gene
network that was primitively involved in bilaterian
appendage development and co-opted to build appendages
(in modern phyla) that are not historically related
as structures. Data from lophotrochozoans are needed to
clarify the pervasiveness of plesiomorphic appendage forming
mechanisms. We assayed the expression of three
arthropod and vertebrate limb gene orthologs, Distal-less
(Dll), dachshund (dac), and optomotor blind (omb), in
direct-developing juveniles of the polychaete Neanthes
arenaceodentata. Parapodial Dll expression marks premorphogenetic
notopodia and neuropodia, becoming restricted
to the bases of notopodial cirri and to ventral
portions of neuropodia. In outgrowing cephalic appendages,
Dll activity is primarily restricted to proximal
domains. Dll expression is also prominent in the brain. dac
expression occurs in the brain, nerve cord ganglia, a pair
of pharyngeal ganglia, presumed interneurons linking a
pair of segmental nerves, and in newly differentiating
mesoderm. Domains of omb expression include the brain,
nerve cord ganglia, one pair of anterior cirri, presumed
precursors of dorsal musculature, and the same pharyngeal
ganglia and presumed interneurons that express dac.
Contrary to their roles in outgrowing arthropod and
vertebrate appendages, Dll, dac, and omb lack comparable
expression in Neanthes appendages, implying independent
evolution of annelid appendage development. We infer
that parapodia and arthropodia are not structurally or
mechanistically homologous (but their primordia might
be), that Dll’s ancestral bilaterian function was in sensory
and central nervous system differentiation, and that
locomotory appendages possibly evolved from sensory
outgrowths
In vivo biofunctional evaluation of hydrogels for disc regeneration
Purpose Regenerative strategies aim to restore the original
biofunctionality of the intervertebral disc. Different
biomaterials are available, which might support disc
regeneration. In the present study, the prospects of success
of two hydrogels functionalized with anti-angiogenic peptides
and seeded with bone marrow derived mononuclear
cells (BMC), respectively, were investigated in an ovine
nucleotomy model.
Methods In a one-step procedure iliac crest aspirates
were harvested and, subsequently, separated BMC were
seeded on hydrogels and implanted into the ovine disc. For
the cell-seeded approach a hyaluronic acid-based hydrogel
was used. The anti-angiogenic potential of newly developed
VEGF-blockers was investigated on ionically crosslinked
metacrylated gellan gum hydrogels. Untreated discs
served as nucleotomy controls. 24 adult merino sheep were
used. After 6 weeks histological, after 12 weeks histological
and biomechanical analyses were conducted.
Results Biomechanical tests revealed no differences
between any of the implanted and nucleotomized discs. All
implanted discs significantly degenerated compared to
intact discs. In contrast, there was no marked difference
between implanted and nucleotomized discs. In tendency,
albeit not significant, degeneration score and disc height
index deteriorated for all but not for the cell-seeded
hydrogels from 6 to 12 weeks. Cell-seeded hydrogels
slightly decelerated degeneration.
Conclusions None of the hydrogel configurations was
able to regenerate biofunctionality of the intervertebral
disc. This might presumably be caused by hydrogel
extrusion. Great importance should be given to the development
of annulus sealants, which effectively exploit the
potential of (cell-seeded) hydrogels for biological disc
regeneration and restoration of intervertebral disc
functioningThis work was supported by the EU-project Disc Regeneration (NMP3-LA-2008-213904). Technical assistance of Iris Baum and the whole animal surgery team of the Institute of Orthopaedic Research and Biomechanics, Ulm, are gratefully acknowledged. DDAHA hydrogels were kindly provided by Cristina Longinotti (DDAHA, Anika Therapeutics, Abano Therme, Italy)
Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii
Background: Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. Results: We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. Conclusion: We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento CientIfico e Tecnologico (CNPq)Coordenacao para Aperfeicoamento de Pessoal de Ensino Superior (CAPES)Fundo de Defesa da Citricultura (FUNDECITRUS
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