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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

E6D25E, HPV16 Asian variant shows specific proteomic pattern correlating in cells transformation and suppressive innate immune response

HPV16 Asian variant (HPV16As) containing E6D25E oncogene, is commonly associated with cervical cancers of Asian populations. To explore a mechanism of E6D25E oncoprotein in carcinogenesis, we compared protein profiles in human keratinocytes expressing E6D25E with E6 of HPV16 prototype (E6Pro). A human cervical keratinocyte cell line, HCK1T, was transduced with retroviruses containing E6D25E or E6Pro genes. Biological properties of E6D25E or E6Pro transduced HCK1T cells were characterized. Protein profiles of the transduced HCK1T cells were analyzed using 2D-PAGE and characterized by mass spectrometry and western blotting. Reactomes of modulated proteins were analyzed by using the Reactome Knowledgebase. The E6D25E and E6Pro oncoproteins were comparable for their abilities to degrade p53 and suppress the induction of p21, and induce cell proliferation. Interestingly, the protein profiles of the HCK1T cells transduced with E6D25E showed specific proteomic patterns different from those with E6Pro. Among altered proteins, more than 1.5-fold up- or down- regulation was observed in E6D25E-expressing cells for gp96 and keratin7 which involved in activation of TLR signaling and transformation of squamocolumnar junction cells, respectively. This report describes new cellular proteins specifically targeted by E6D25E oncoprotein that may contribute to impair immune response against viral infection and cell transformation associated with oncogenic property of HPV16As variant. - Highlights: • E6D25E HPV16 specifically modulates protein profile of human keratinocytes. • E6D25E HPV16 modulates protein profile which involves in TLR signalling and transformation of squamocolumnar junction cells. • E6D25E oncoprotein may correlate to impair of immune response against viral infection and cells transformation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Arsenic repartitioning during biogenic sulfidization and transformation of ferrihydrite

Iron (hydr)oxides are strong sorbents of arsenic (As) that undergo reductive dissolution and transformation upon reaction with dissolved sulfide. Here we examine the transformation and dissolution of As-bearing ferrihydrite and subsequent As repartitioning amongst secondary phases during biotic sulfate reduction. Columns initially containing As(V)-ferrihydrite coated sand, inoculated with the sulfate reducing bacteria Desulfovibrio vulgaris (Hildenborough), were eluted with artificial groundwater containing sulfate and lactate. Rapid and consistent sulfate reduction coupled with lactate oxidation is observed at low As(V) loading (10% of the adsorption maximum). The dominant Fe solid phase transformation products at low As loading include amorphous FeS within the zone of sulfate reduction (near the inlet of the column) and magnetite downstream where Fe(II)(aq) concentrations increase; As is displaced from the zone of sulfidogenesis and Fe(III)(s) depletion. At high As(V) loading (50% of the adsorption maximum), sulfate reduction and lactate oxidation are initially slow but gradually increase over time, and all As(V) is reduced to As(III) by the end of experimentation. With the higher As loading, green rust(s), as opposed to magnetite, is a dominant Fe solid phase product. Independent of loading, As is strongly associated with magnetite and residual ferrihydrite, while being excluded from green rust and iron sulfide. Our observations illustrate that sulfidogenesis occurring in proximity with Fe (hydr)oxides induce Fe solid phase transformation and changes in As partitioning; formation of As sulfide minerals, in particular, is inhibited by reactive Fe(III) or Fe(II) either through sulfide oxidation or complexation.

58 GEOSCIENCES↗
DOE OSTI2018

Temperature-dependent plastic deformation mechanisms of a Cu/steel transforming nanolamellar composite

Metallic nanolamellar composites possess unusually high strength owing to the high density interfaces that impede dislocation nucleation and migration. Meanwhile most nanolamellar composites show limited ductility in tension due to the lack of effective deformation mechanisms. Martensitic transformation, once multiplied with dislocations, can improve the work hardening efficiently during plastic deformation, leading to enhanced ductility. It is thereby of interest to investigate the mechanical behavior of nanolamellar composites that contain martensitic constituents. We here report on the temperature-dependent deformation mechanisms of a nanolamellar Cu/carbon-steel composite wire with a high volume fraction of retained austenite. Tensile tests at various temperatures reveal that the mechanical behavior of the composite is sensitive to temperature, analogous to the feature of deformation-induced martensitic transformation in steels with mechanically metastable austenite. In particular, a maximum uniform elongation of 63% is achieved at 180 degrees C. In situ synchrotron X-ray studies suggest that the deformation mechanisms of the composite are a result of the competition between transformation and slip of the retained austenite. Finally, a deformation mechanism map is proposed and the boundary between stress- and strain-induced martensitic transformation is clearly identified.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Acetylation of the c-MYC oncoprotein is required for cooperation with the HTLV-1 p30{sup II} accessory protein and the induction of oncogenic cellular transformation by p30{sup II}/c-MYC

The human T-cell leukemia retrovirus type-1 (HTLV-1) p30{sup II} protein is a multifunctional latency-maintenance factor that negatively regulates viral gene expression and deregulates host signaling pathways involved in aberrant T-cell growth and proliferation. We have previously demonstrated that p30{sup II} interacts with the c-MYC oncoprotein and enhances c-MYC-dependent transcriptional and oncogenic functions. However, the molecular and biochemical events that mediate the cooperation between p30{sup II} and c-MYC remain to be completely understood. Herein we demonstrate that p30{sup II} induces lysine-acetylation of the c-MYC oncoprotein. Acetylation-defective c-MYC Lys→Arg substitution mutants are impaired for oncogenic transformation with p30{sup II} in c-myc{sup −/−} HO15.19 fibroblasts. Using dual-chromatin-immunoprecipitations (dual-ChIPs), we further demonstrate that p30{sup II} is present in c-MYC-containing nucleoprotein complexes in HTLV-1-transformed HuT-102 T-lymphocytes. Moreover, p30{sup II} inhibits apoptosis in proliferating cells expressing c-MYC under conditions of genotoxic stress. These findings suggest that c-MYC-acetylation is required for the cooperation between p30{sup II}/c-MYC which could promote proviral replication and contribute to HTLV-1-induced carcinogenesis. - Highlights: • Acetylation of c-MYC is required for oncogenic transformation by HTLV-1 p30{sup II}/c-MYC. • Acetylation-defective c-MYC mutants are impaired for foci-formation by p30{sup II}/c-MYC. • The HTLV-1 p30{sup II} protein induces lysine-acetylation of c-MYC. • p30{sup II} is present in c-MYC nucleoprotein complexes in HTLV-1-transformed T-cells. • HTLV-1 p30{sup II} inhibits apoptosis in c-MYC-expressing proliferating cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Dynamic Nanoscale Spatial Heterogeneity in a Perovskite-to-Brownmillerite Topotactic Phase Transformation

Phase transitions are omnipresent in modern condensed matter physics and its applications. In solids, first-order phase transformations typically occur by nucleation and growth under nonequilibrium conditions. Under constant external conditions, e.g., constant annealing temperature and pressure, the nucleation and growth dynamics are often thought of as spatially and temporally independent. Here, in situ Bragg X-ray photon correlation spectroscopy (XPCS) reveals nanoscale spatial and dynamical heterogeneity in the perovskite-to-brownmillerite topotactic phase transformation in La 0.7 Sr 0.3 CoO 3 thin films annealed under constant reducing conditions over a time span of multiple hours. Specifically, a time scale associated with domain growth remains stable, with a corresponding domain wall speed of v d = 6 ± 0.5 × 10 –4 nm/s (2 ± 0.2 nm/h), while a slower time scale, associated with temperature-driven depinning of domains, leads to accelerating dynamics with time scales following an aging power law with exponent −2.2 ± 0.5. This experiment demonstrates that Bragg XPCS is a powerful tool to study nanoscale dynamics in structural phase transformations, with the ability to extract quantitative average values related to nanodomain motion in situ. Furthermore, the results are relevant for phase engineering of phase-change devices, as they show that nanoscale dynamics, linked to domain and domain-wall motion, can continuously evolve and speed up with time, even hours after the initiation of the phase transformation, with potential repercussions on electrical performance.

X-ray photon correlation spectroscopy↗
DOE OSTI2010

Supersymmetric reciprocal transformation and its applications

The supersymmetric analog of the reciprocal transformation is introduced. This is used to establish a transformation between one of the supersymmetric Harry Dym equations and the supersymmetric modified Korteweg-de Vries equation. The reciprocal transformation, as a Baecklund-type transformation between these two equations, is adopted to construct a recursion operator for the supersymmetric Harry Dym equation. By proper factorization of the recursion operator, a bi-Hamiltonian structure is found for the supersymmetric Harry Dym equation. Furthermore, a supersymmetric Kawamoto equation is proposed and is associated with the supersymmetric Sawada-Kotera equation. The recursion operator and odd bi-Hamiltonian structure of the supersymmetric Kawamoto equation are also constructed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

Bell-polynomial manipulations on the Baecklund transformations and Lax pairs for some soliton equations with one Tau-function

In the framework of Bell-polynomial manipulations, under investigation hereby are three single-field bilinearizable equations: the (1+1)-dimensional shallow water wave model, Boiti-Leon-Manna-Pempinelli model, and (2+1)-dimensional Sawada-Kotera model. Based on the concept of scale invariance, a direct and unifying Bell-polynomial scheme is employed to achieve the Baecklund transformations and Lax pairs associated with those three soliton equations. Note that the Bell-polynomial expressions and Bell-polynomial-typed Baecklund transformations for those three soliton equations can be, respectively, cast into the bilinear equations and bilinear Baecklund transformations with symbolic computation. Consequently, it is also shown that the Bell-polynomial-typed Baecklund transformations can be linearized into the corresponding Lax pairs.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Electric-field-induced paraelectric to ferroelectric phase transformation in prototypical polycrystalline BaTiO{sub 3}

An electric-field-induced paraelectric cubic to ferroelectric tetragonal phase transformation has been directly observed in prototypical polycrystalline BaTiO{sub 3} at temperatures above the Curie point (T{sub C}) using in situ high-energy synchrotron X-ray diffraction. The transformation persisted to a maximum temperature of 4 °C above T{sub C}. The nature of the observed field-induced transformation and the resulting development of domain texture within the induced phase were dependent on the proximity to the transition temperature, corresponding well to previous macroscopic measurements. The transition electric field increased with increasing temperature above T{sub C}, while the magnitude of the resultant tetragonal domain texture at the maximum electric field (4 kV mm{sup −1}) decreased at higher temperatures. These results provide insights into the phase transformation behavior of a prototypical ferroelectric and have important implications for the development of future large-strain phase-change actuator materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Modification of Lie's transform perturbation theory for charged particle motion in a magnetic field

It is pointed out that the conventional Lie transform perturbation theory for the guiding center motion of charged particles in a magnetic field needs to be modified for ordering inconsistency. There are two reasons. First, the ordering difference between the temporal variation of gyrophase and that of the other phase space coordinates needs to be taken into account. Second, it is also important to note that the parametric limit of the derivative of a function is not equivalent to the derivative of the limit function. When these facts are taken into account, the near identity transformation rule for one form related to the Lagrangian is modified. With the modified near identity transformation rule, the drift motion of charged particles can be described in the first order, instead of the second order and beyond through a tedious expansion process as in the conventional formulation. Here, this resolves the discrepancy between the direct and Lie transform treatments in the Lagrangian perturbation theory for charged particle motion in a magnetic field.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Composition-dependent ordering transformations in Pt–Fe nanoalloys

Significance Dynamically understanding the microscopic processes governing ordering transformations has rarely been attained. The situation becomes even more challenging for nanoscale alloys, where the significantly increased surface-area-to-volume ratio not only opens up a variety of additional freedoms to initiate an ordering transformation but also allows for kinetic interplay between the surface and bulk due to their close proximity. We provide direct evidence of the microscopic processes controlling the ordering transformation through the surface–bulk interplay in Pt–Fe nanoalloys and new features rendered by variations in alloy composition and chemical stimuli. These results provide a mechanistic detail of ordering transformation phenomena which are widely relevant to nanoalloys as chemical ordering occurs in most multicomponent materials under suitable environmental bias.

25 ENERGY STORAGE↗
DOE OSTI2017

Simplifying the EFT of Inflation: generalized disformal transformations and redundant couplings

We study generalized disformal transformations, including derivatives of the metric, in the context of the Effective Field Theory of Inflation. All these transformations do not change the late-time cosmological observables but change the coefficients of the operators in the action: some couplings are effectively redundant. At leading order in derivatives and up to cubic order in perturbations, one has 6 free functions that can be used to set to zero 6 of the 17 operators at this order. This is used to show that the tensor three-point function cannot be modified at leading order in derivatives, while the scalar-tensor-tensor correlator can only be modified by changing the scalar dynamics. At higher order in derivatives there are transformations that do not affect the Einstein-Hilbert action: one can find 6 additional transformations that can be used to simplify the inflaton action, at least when the dynamics is dominated by the lowest derivative terms. We also identify the leading higher-derivative corrections to the tensor power spectrum and bispectrum.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

A Rotational Control in Medium-Voltage Modular Solid-State Transformer-Based Converter System

This article presents a novel control strategy to significantly reduce the high-frequency transformer loss in a modular solid-state transformer (SST) based converter system. The modular SST design is based on an ac-dc power-electronic building block comprised of an H-bridge at the ac input and a bidirectional soft-switching isolated dc-dc converter with a medium-voltage insulated high-frequency transformer. The ac terminals of input H-bridges are connected in series and directly coupled to the medium-voltage ac line, while the output dc terminals are all connected in parallel at a low voltage. The key innovation described in this paper, without sacrificing the output performance, is the control scheme that reduces core and winding losses associated with the dc-dc resonant stage by turning off the selected dc-dc converters in synchronism with the line voltage. The prototype for the test described in this paper is based on a modular SST where each module is rated at 50 kVA, with a 200 kHz transformer using 1.7 kV silicon carbide discrete mosfets, but the described control concepts are more broadly applicable to similar topologies.

42 ENGINEERING↗
DOE OSTI2021

SiC-Based 5-kV Universal Modular Soft-Switching Solid-State Transformer (M-S4T) for Medium-Voltage DC Microgrids and Distribution Grids

Medium-voltage DC (MVDC) grids are attractive for electric aircraft and ship power systems, battery energy storage system (BESS), fast charging electric vehicle (EV), etc. Such EV or BESS applications need isolated bidirectional MVDC to LVDC or LVAC converters. However, the existing Si-based solutions cannot fulfill the requirements of a high-efficiency and robust converter for MVDC grids. This paper presents a 5 kV SiC-based universal modular solid-state transformer (SST). This universal current-source SST can interface either a LVAC or LVDC grid with a MVDC grid in single-stage power conversion, while the conventional dual active bridge (DAB) converter needs an additional inverter. The proposed SST module using 3.3 kV SiC MOSFETs and diodes is bidirectional and can serve as a building block in series or parallel for higher-voltage higher-power systems. The topology of each module is based on the soft-switching solid-state transformer (S4T) with reduced conduction loss, which features reduced EMI through controlled dv/dt, and high efficiency with full-range ZVS for main devices and ZCS for auxiliary devices. Operation principle of the modular S4T (M-S4T), capacitor voltage balancing control between the cascaded modules, design of components including a medium-voltage (MV) medium-frequency transformer (MFT) to realize a 50 kVA 5 kV DC to 600 V DC or 480 V AC M-S4T are presented. Importantly, the MV MFT prototype achieves very low leakage inductance (0.13%) and 15 kV insulation with coaxial cables and nanocrystalline cores. Here, the proposed universal modular SST is compared against the DAB solution and verified with DC-DC and DC-AC simulation and 4 kV experimental results. Significantly, the MV experimental results of a modular DC transformer with each module at MVDC are rarely covered in the literature and reported for the first time.

14 SOLAR ENERGY↗
DOE OSTI2023

Atomic Dynamics of Multi‐Interfacial Migration and Transformations

Redox-induced interconversions of metal oxidation states typically result in multiple phase boundaries that separate chemically and structurally distinct oxides and suboxides. Directly probing such multi-interfacial reactions is challenging because of the difficulty in simultaneously resolving the multiple reaction fronts at the atomic scale. Using the example of CuO reduction in H 2 gas, a reaction pathway of CuO → monoclinic m-Cu 4 O 3 → Cu 2 O is demonstrated and identifies interfacial reaction fronts at the atomic scale, where the Cu 2 O/m-Cu 4 O 3 interface shows a diffuse-type interfacial transformation; while the lateral flow of interfacial ledges appears to control the m-Cu 4 O 3 /CuO transformation. Together with atomistic modeling, it is shown that such a multi-interface transformation results from the surface-reaction-induced formation of oxygen vacancies that diffuse into deeper atomic layers, thereby resulting in the formation of the lower oxides of Cu 2 O and m-Cu 4 O 3 , and activate the interfacial transformations. In conclusion, these results demonstrate the lively dynamics at the reaction fronts of the multiple interfaces and have substantial implications for controlling the microstructure and interphase boundaries by coupling the interplay between the surface reaction dynamics and the resulting mass transport and phase evolution in the subsurface and bulk.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Convexity Conditions and the Legendre-Fenchel Transform for the Product of Finitely Many Positive Definite Quadratic Forms

While the product of finitely many convex functions has been investigated in the field of global optimization, some fundamental issues such as the convexity condition and the Legendre-Fenchel transform for the product function remain unresolved. Focusing on quadratic forms, this paper is aimed at addressing the question: When is the product of finitely many positive definite quadratic forms convex, and what is the Legendre-Fenchel transform for it? First, we show that the convexity of the product is determined intrinsically by the condition number of so-called 'scaled matrices' associated with quadratic forms involved. The main result claims that if the condition number of these scaled matrices are bounded above by an explicit constant (which depends only on the number of quadratic forms involved), then the product function is convex. Second, we prove that the Legendre-Fenchel transform for the product of positive definite quadratic forms can be expressed, and the computation of the transform amounts to finding the solution to a system of equations (or equally, finding a Brouwer's fixed point of a mapping) with a special structure. Thus, a broader question than the open 'Question 11' in Hiriart-Urruty (SIAM Rev. 49, 225-273, 2007) is addressed in this paper.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Development of a shuttle plasmid without host restriction sites for efficient transformation and heterologous gene expression in Clostridium cellulovorans

Clostridium cellulovorans capable of producing large amounts of acetate and butyrate from cellulose is a promising candidate for biofuels and biochemicals production from lignocellulosic biomass. However, the restriction modification (RM) systems of C. cellulovorans hindered the application of existing shuttle plasmids for metabolic engineering of this organism. To overcome the hurdle of plasmid digestion by host, a new shuttle plasmid (pYL001) was developed to remove all restriction sites of two major RM systems of C. cellulovorans , Cce 743 I and Cce 743 II. The pYL001 plasmid remained intact after challenge by C. cellulovorans cell extract. Post-electroporation treatments and culturing conditions were also modified to improve cell growth and colony formation on agar plates. With the improvements, the pYL001 plasmid, without in-vivo methylation, was readily transformed into C. cellulovorans with colonies of recombinant cells formed on agar plates within 24 h. Three pYL001-derived recombinant plasmids free of Cce 743 I/ Cce 743 II restriction sites, after synonymous mutation of the heterologous genes, were constructed and transformed into C. cellulovorans . Functional expression of these genes was confirmed with butanol and ethanol production from glucose in batch fermentations by the transformants. In conclusion, the pYL001 plasmid and improved transformation method can facilitate further metabolic engineering of C. cellulovorans for cellulosic butanol production.

09 BIOMASS FUELS↗
DOE OSTI2012

The enigma of post-perovskite anisotropy: deformation versus transformation textures

The D'' region that lies just above the core mantle boundary exhibits complex anisotropy that this is likely due to preferred orientation (texturing) of the constituent minerals. (Mg,Fe)SiO{sub 3} post-perovskite is widely thought to be the major mineral phase of the D''. Texture development has been studied in various post-perovskite phases (MgSiO{sub 3}, MgGeO{sub 3}, and CaIrO{sub 3}), and different results were obtained. To clarify this controversy, we report on transformation and deformation textures in MgGeO{sub 3} post-perovskite synthesized and deformed at room temperature in the diamond anvil cell. Transformed from the enstatite phase, MgGeO{sub 3} post-perovskite exhibits a transformation texture characterized by (100) planes at high angles to the direction of compression. Upon subsequent deformation, this texture changes and (001) lattice planes become oriented nearly perpendicular to compression, consistent with dominant (001)[100] slip. When MgGeO{sub 3} post-perovskite is synthesized from the perovskite phase, a different transformation texture is observed. This texture has (001) planes at high angle to compression and becomes slightly stronger upon compression. We also find that the yield strength of MgGeO{sub 3} post-perovskite is dependent on grain size and texture. Finer-grained samples exhibit higher yield strength and are harder to induce plastic deformation. Strong textures also affect the yield strength and can result in higher differential stresses. The inferred dominant (001) slip for pPv is significant for geophysics, because, when applied to geodynamic convection models, it predicts the observed anisotropies of S-waves as well as an anti-correlation between P- and S-waves.

36 MATERIALS SCIENCE↗
DOE OSTI2012

The development of coil short circuits when transformer windings become contaminated with metal-containing colloidal particles

The radiational-thermal development of coil short circuits due to the action of partial discharges of the first kind when the windings of transformers, autotransformers and shunting reactors become contaminated with metal-containing colloidal particles, formed in the transformer oil as a result of the interaction of the oil with the constructional materials (the copper of the windings, the iron of the tank, the core etc.) is considered. Acriterion of dangerous contamination of the coil insulation of the windings by metal-containing colloidal particles is proposed, namely, 3% of the mass content of copper and iron in it, which, if exceeded, may serve as a basis for recognizing the state of transformers, autotransformers and shunting reactors at a voltage of 110 kV and above the limit. It is shown that filters for continuously cleaning the oil play a considerable role in prolonging the life of transformer equipment.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗