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Zhang, Weiguo

Publications and source records attributed to Zhang, Weiguo.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Room temperature polar and weak-ferromagnetic oxide with low dielectric loss

Single-phase materials that are simultaneously ferroelectric and ferromagnetic at room temperature are promising for devices such as non-volatile random-access memory. Perovskite BiFeO 3 which crystallizes in the polar rhombohedral structure (R3c) is ferroelectric and antiferromagnetic at room temperature. Here, we report a family of perovskite oxides in the BiFeO 3 – Bi 2/3 TiO 3 – ATiO 3 (where A 2+ is divalent alkaline earth metal ions e.g., Ca 2+ , Sr 2+ , Ba 2+ ) ternary phase diagram that is polar as well as weak ferromagnetic above room temperature. The composition (Bi 0.9167 A 0.075 )(Fe 0.9 Ti 0.1 )O 3 crystallizes in the polar rhombohedral structure space group R3c as corroborated by powder X-ray and neutron diffraction analysis. The nearly pure A-site perovskite possesses a long-range magnetic ordering above room temperature. Finally, these perovskites show a low dielectric loss, and the electrical response is dominated by grain contributions below 723 K.

42 ENGINEERING↗
DOE OSTI2022

Centromere/kinetochore protein genes for cancer diagnosis, prognosis and treatment selection

The invention described in the application relates to a panel of gene expression markers for patient with a tumor. The invention thus provides methods and compositions, e.g., kits, for evaluating gene expression levels of the markers and methods of using such gene expression levels to evaluate the likelihood of disease progression or response to chemotherapy or radiation therapy. Such information can be used in determining prognosis and treatment options for cancer patients.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2014

Calibration of International Space Station (ISS) Node 1 Vibro-Acoustic Model

Reported here is the ability of utilizing the Energy Finite Element Method (E-FEM) to predict the vibro-acoustic sound fields within the International Space Station (ISS) Node 1 and to compare the results with actual measurements of leak sounds made by a one atmosphere to vacuum leak through a small hole in the pressure wall of the Node 1 STA module during its period of storage at Stennis Space Center (SSC). While the E-FEM method represents a reverberant sound field calculation, of importance to this application is the requirement to also handle the direct field effect of the sound generation. It was also important to be able to compute the sound fields in the ultrasonic frequency range. This report demonstrates the capability of this technology as applied to this type of application.

Zhang, Weiguo↗
NASA NTRS2014

Calibration of International Space Station (ISS) Node 1 Vibro-Acoustic Model-Report 2

Reported here is the capability of the Energy Finite Element Method (E-FEM) to predict the vibro-acoustic sound fields within the International Space Station (ISS) Node 1 and to compare the results with simulated leak sounds. A series of electronically generated structural ultrasonic noise sources were created in the pressure wall to emulate leak signals at different locations of the Node 1 STA module during its period of storage at Stennis Space Center (SSC). The exact sound source profiles created within the pressure wall at the source were unknown, but were estimated from the closest sensor measurement. The E-FEM method represents a reverberant sound field calculation, and of importance to this application is the requirement to correctly handle the direct field effect of the sound generation. It was also important to be able to compute the sound energy fields in the ultrasonic frequency range. This report demonstrates the capability of this technology as applied to this type of application.

Zhang, Weiguo↗