Browsing by Author "Wang, Jian"
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Item Engineered bacteria produce succinate from sucrose(2015-02-24) San, Ka-Yiu; Bennett, George N.; Wang, Jian; Rice University; United States Patent and Trademark OfficeBacteria optimized to produce succinate and other feedstocks by growing on low cost carbon sources, such as sucrose.Item Enhanced Electron Correlation and Significantly Suppressed Thermal Conductivity in Dirac Nodal-Line Metal Nanowires by Chemical Doping(Wiley, 2023) Coughlin, Amanda L.; Pan, Zhiliang; Hong, Jeonghoon; Zhang, Tongxie; Zhan, Xun; Wu, Wenqian; Xie, Dongyue; Tong, Tian; Ruch, Thomas; Heremans, Jean J.; Bao, Jiming; Fertig, Herbert A.; Wang, Jian; Kim, Jeongwoo; Zhu, Hanyu; Li, Deyu; Zhang, ShixiongEnhancing electron correlation in a weakly interacting topological system has great potential to promote correlated topological states of matter with extraordinary quantum properties. Here, the enhancement of electron correlation in a prototypical topological metal, namely iridium dioxide (IrO2), via doping with 3d transition metal vanadium is demonstrated. Single-crystalline vanadium-doped IrO2 nanowires are synthesized through chemical vapor deposition where the nanowire yield and morphology are improved by creating rough surfaces on substrates. Vanadium doping leads to a dramatic decrease in Raman intensity without notable peak broadening, signifying the enhancement of electron correlation. The enhanced electron correlation is further evidenced by transport studies where the electrical resistivity is greatly increased and follows an unusual T$\sqrt T $ dependence on the temperature (T). The lattice thermal conductivity is suppressed by an order of magnitude via doping even at room temperature where phonon-impurity scattering becomes less important. Density functional theory calculations suggest that the remarkable reduction of thermal conductivity arises from the complex phonon dispersion and reduced energy gap between phonon branches, which greatly enhances phase space for phonon–phonon Umklapp scattering. This work demonstrates a unique system combining 3d and 5d transition metals in isostructural materials to enrich the system with various types of interactions.Item High-velocity projectile impact induced 9R phase in ultrafine-grained aluminium(Springer Nature, 2017) Xue, Sichuang; Fan, Zhe; Lawal, Olawale B.; Thevamaran, Ramathasan; Li, Qiang; Liu, Yue; Yu, K.Y.; Wang, Jian; Thomas, Edwin L.; Wang, Haiyan; Zhang, XinghangAluminium typically deforms via full dislocations due to its high stacking fault energy. Twinning in aluminium, although difficult, may occur at low temperature and high strain rate. However, the 9R phase rarely occurs in aluminium simply because of its giant stacking fault energy. Here, by using a laser-induced projectile impact testing technique, we discover a deformation-induced 9R phase with tens of nm in width in ultrafine-grained aluminium with an average grain size of 140 nm, as confirmed by extensive post-impact microscopy analyses. The stability of the 9R phase is related to the existence of sessile Frank loops. Molecular dynamics simulations reveal the formation mechanisms of the 9R phase in aluminium. This study sheds lights on a deformation mechanism in metals with high stacking fault energies.Item RobustPPG: camera-based robust heart rate estimation using motion cancellation(Optica Publishing Group, 2022) Maity, Akash Kumar; Maity, Akash Kumar; Wang, Jian; Wang, Jian; Wang, Jian; Sabharwal, Ashutosh; Sabharwal, Ashutosh; Nayar, Shree K.; Nayar, Shree K.Camera-based heart rate measurement is becoming an attractive option as a non-contact modality for continuous remote health and engagement monitoring. However, reliable heart rate extraction from camera-based measurement is challenging in realistic scenarios, especially when the subject is moving. In this work, we develop a motion-robust algorithm, labeled RobustPPG, for extracting photoplethysmography signals (PPG) from face video and estimating the heart rate. Our key innovation is to explicitly model and generate motion distortions due to the movements of the person’s face. We use inverse rendering to obtain the 3D shape and albedo of the face and environment lighting from video frames and then render the human face for each frame. The rendered face is similar to the original face but does not contain the heart rate signal; facial movements alone cause pixel intensity variation in the generated video frames. Finally, we use the generated motion distortion to filter the motion-induced measurements. We demonstrate that our approach performs better than the state-of-the-art methods in extracting a clean blood volume signal with over 2 dB signal quality improvement and 30% improvement in RMSE of estimated heart rate in intense motion scenarios.