Engineering topics

Yang, Fan

Publications and source records attributed to Yang, Fan.

At least 163 records · Page 9

DOE OSTI2018

Enhanced light–matter interaction of aligned armchair graphene nanoribbons using arrays of plasmonic nanoantennas

We couple photoluminescent semiconducting 7-atom wide armchair edge graphene nanoribbons to plasmonic nanoantenna arrays and demonstrate an enhancement of the photoluminescence and Raman scattering intensity of the nanoribbons by more than an order of magnitude averaged over large areas, and by three orders of magnitude in the hot spots of plasmonic antennas. The increase in signal allows us to study Raman spectra with high signal-to-noise ratio. Using plasmonic enhancement we are able to detect the off-resonant Raman scattering from the modified radial breathing-like mode (RBLM) due to physisorbed molecules, the 3rd order RBLM, and C-H vibrations. We find excellent agreement between experimental data and simulations describing the spectral dependence of the enhancement and modifications of the polarization anisotropy. The strong field gradients in the optical near-field further allow us to probe the subwavelength coherence properties of the phonon modes in the nanoribbons. We theoretically model this considering a finite phonon correlation length along the GNR direction. Our results allow estimating the correlation length in graphene nanoribbons.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Phase Modulation of (1T‐2H)‐MoSe2/TiC‐C Shell/Core Arrays via Nitrogen Doping for Highly Efficient Hydrogen Evolution Reaction

Abstract Tailoring molybdenum selenide electrocatalysts with tunable phase and morphology is of great importance for advancement of hydrogen evolution reaction (HER). In this work, phase‐ and morphology‐modulated N‐doped MoSe 2 /TiC‐C shell/core arrays through a facile hydrothermal and postannealing treatment strategy are reported. Highly conductive TiC‐C nanorod arrays serve as the backbone for MoSe 2 nanosheets to form high‐quality MoSe 2 /TiC‐C shell/core arrays. Impressively, continuous phase modulation of MoSe 2 is realized on the MoSe 2 /TiC‐C arrays. Except for the pure 1T‐MoSe 2 and 2H‐MoSe 2 , mixed (1T‐2H)‐MoSe 2 nanosheets are achieved in the N‐MoSe 2 by N doping and demonstrated by spherical aberration electron microscope. Plausible mechanism of phase transformation and different doping sites of N atom are proposed via theoretical calculation. The much smaller energy barrier, longer HSe bond length, and diminished bandgap endow N‐MoSe 2 /TiC‐C arrays with substantially superior HER performance compared to 1T and 2H phase counterparts. Impressively, the designed N‐MoSe 2 /TiC‐C arrays exhibit a low overpotential of 137 mV at a large current density of 100 mA cm −2 , and a small Tafel slope of 32 mV dec −1 . Our results pave the way to unravel the enhancement mechanism of HER on 2D transition metal dichalcogenides by N doping.

Deng, Shengjue↗

DOE OSTI2018

Predictive modeling of battery degradation and greenhouse gas emissions from U.S. state-level electric vehicle operation

Electric vehicles (EVs) are widely promoted as clean alternatives to conventional vehicles for reducing greenhouse gas (GHG) emissions from ground transportation. However, the battery undergoes a sophisticated degradation process during EV operations and its effects on EV energy consumption and GHG emissions are unknown. Here we show on a typical 24 kWh lithium-manganese-oxide–graphite battery pack that the degradation of EV battery can be mathematically modeled to predict battery life and to study its effects on energy consumption and GHG emissions from EV operations. We found that under US state-level average driving conditions, the battery life is ranging between 5.2 years in Florida and 13.3 years in Alaska under 30% battery degradation limit. The battery degradation will cause a 11.5–16.2% increase in energy consumption and GHG emissions per km driven at 30% capacity loss. This study provides a robust analytical approach and results for supporting policy making in prioritizing EV deployment in the U.S.

Science & Technology - Other Topics↗

DOE OSTI2018

Tailoring Bandgap of Perovskite BaTiO 3 by Transition Metals Co-Doping for Visible-Light Photoelectrical Applications: A First-Principles Study

The physical and chemical properties of V-M" and Nb-M" (M" is 3d or 4d transition metal) co-doped BaTiO 3 were studied by first-principles calculation based on density functional theory. Our calculation results show that V-M" co-doping is more favorable than Nb-M" co-doping in terms of narrowing the bandgap and increasing the visible-light absorption. In pure BaTiO 3 , the bandgap depends on the energy levels of the Ti 3d and O 2p states. The appropriate co-doping can effectively manipulate the bandgap by introducing new energy levels interacting with those of the pure BaTiO 3 . The optimal co-doping effect comes from the V-Cr co-doping system, which not only has smaller impurity formation energy, but also significantly reduces the bandgap. Detailed analysis of the density of states, band structure, and charge-density distribution in the doping systems demonstrates the synergistic effect induced by the V and Cr co-doping. The results can provide not only useful insights into the understanding of the bandgap engineering by element doping, but also beneficial guidance to the experimental study of BaTiO 3 for visible-light photoelectrical applications.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Dihydroartemisinin potentiates antitumor activity of 5-fluorouracil against a resistant colorectal cancer cell line

Although the combination of chemotherapy and surgical resection has effectively increased the survival rate of colorectal cancer patients in recent decades, acquired drug resistance is still a problem that leads to treatment failure. Dihydroartemisinin (DHA), a semisynthetic derivative of artemisinin, has recently been reported to show anticancer effects against numerous types of cancer, including colorectal cancer. This study showed that DHA exerted a strong anticancer effect against several colorectal cancer cell lines. We also found that p53 knockout colorectal cancer HCT116 cells (HCT116 TP53{sup −/−}) were not sensitive to 5-fluorouracil (5-FU) treatment, unlike wild-type HCT116 cells. Interestingly, co-treatment with DHA could effectively restore the anticancer effect of 5-FU against HCT116 TP53{sup −/−} cells, which manifested as the inhibition of proliferation and induction of reactive oxygen species (ROS)-mediated apoptosis and was accompanied by the upregulation of B-cell lymphoma 2 (BCL-2) and downregulation of the BCL-2-associated X protein (BAX). These findings suggested that DHA could effectively sensitize cells to 5-FU through ROS-mediated apoptosis and the alteration of the BCL-2/BAX expression ratio, which indicated that this may be one of the mechanisms of the DHA-promoted 5-FU anticancer effect.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Long noncoding RNA LNC473 inhibits the ubiquitination of survivin via association with USP9X and enhances cell proliferation and invasion in hepatocellular carcinoma cells

Highlights: • LNC473 was overexpressed in HCC tissues and correlated with tumor size, BCLC stage, vascular invasion and poor prognosis. • LNC473 enhanced HCC cell proliferation and invasion and induced epithelial–mesenchymal transition (EMT) process. • LNC473 associated with oncoprotein survivin and regulates its stability. • LNC473 recruited USP9X to inhibit survivin ubiquitination and then increase its expression. Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Recent studies reported that lncRNA LINC00473 (LNC473) was involved in cancer progression. However, the clinical significance and functional role of LNC473 in HCC progression is still unknown. In the present study, we found that the LNC473 expression was markedly elevated in HCC tissues and correlated with bigger tumor size, higher BCLC stage, vascular invasion and poor prognosis. Gain- and loss-of-function assay showed that LNC473 enhanced HCC cell proliferation and invasion and induced epithelial–mesenchymal transition (EMT) process. Mechanistically, LNC473 associated with oncoprotein survivin and regulates its stability. Moreover, LNC473 could recruit deubiquitinase USP9X to inhibit the ubiquitination level of survivin and then increase survivin expression. Therefore, our results suggest that LNC473 exerts its functions as an oncogene in HCC progression and may be a therapeutic target for HCC treatment.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

The crystal facet-dependent electrochemical performance of TiO 2 nanocrystals for heavy metal detection: Theoretical prediction and experimental proof

Tailored design/fabrication of electroanalytical materials with highly-active exposed crystal planes is of great importance for the development of electrochemical sensing. In this work, combining experimental and theoretical efforts, we reported a facile strategy to fabricate TiO 2 nanocrystals with tunable electrochemical performance for heavy metal detection. Density functional theory (DFT) calculations indicated that TiO 2 (001) facet showed relative larger adsorption energy and lower diffusion energy barrier toward heavy metal ions, which is favorable for obtaining better electrochemical stripping behaviors. Based on this prediction, a series of TiO 2 nanocrystals with different ratios of exposed (001) and (101) facets were synthesized. Electrochemical stripping experiments further demonstrated that with the increase of the percentage of exposed (001) facet, the sensitivity toward Pb(II) and Cd(II) was increased accordingly. When the percentage of exposed (001) facet was increased from 7% to 80%, the sensitivity increased by 190% and 93% for Pb(II) and Cd(II), respectively. In conclusion, our work provides an effective route to construct advanced electroanalytical materials for sensing.

47 OTHER INSTRUMENTATION↗

DOE OSTI2018

Scaling of drizzle virga depth with cloud thickness for marine stratocumulus clouds

Drizzle plays a crucial role in cloud lifetime and radiation properties of marine stratocumulus clouds. Understanding where drizzle exists in the sub-cloud layer, which depends on drizzle virga depth, can help us better understand where below-cloud scavenging and evaporative cooling and moisturizing occur. In this study, we examine the statistical properties of drizzle frequency and virga depth of marine stratocumulus based on unique ground-based remote sensing data. Results show that marine stratocumulus clouds are drizzling nearly all the time. In addition, we derive a simple scaling analysis between drizzle virga thickness and cloud thickness. Our analytical expression agrees with the observational data reasonable well, which suggests that our formula provides a simple parameterization for drizzle virga of stratocumulus clouds suitable for use in other models.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

Scanning Quantum Cryogenic Atom Microscope (Final Technical Report)

The SQCRAMscope, Scanning Quantum Cryogenic Atom Microscope, is a novel scanning probe microscope we developed during this DOE fund period. It is now capable of imaging transport in cryogenically cooled solid-state samples, as we have recently demonstrated with iron-based pnictide superconductors. As such, it opens a new frontier in the quantum-based metrology of materials and is the first example of the direct marriage of ultracold AMO physics with condensed matter physics. We predict the SQCRAMscope will become an important element in the toolbox for exploring strongly correlated and topologically nontrivial materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2018

Greatest soil microbial diversity found in micro-habitats

Microbial interactions occur in habitats much smaller than typically considered in classic ecological studies. This study uses soil aggregates to examine soil microbial community composition and structure of both bacteria and fungi at a microbially relevant scale. Aggregates were isolated from three land management systems in central Iowa, USA to test if aggregate-level microbial responses were sensitive to large-scale shifts in plant community and management practices. Bacteria and fungi exhibited similar patterns of community structure and diversity among soil aggregates, regardless of land management. Microaggregates supported more diverse microbial communities, both taxonomically and functionally. Calculation of a weighted proportional whole soil diversity, which accounted for microbes found in aggregate fractions, resulted in 65% greater bacterial richness and 100% greater fungal richness over independently sampled whole soil. Our results show microaggregates support a previously unrecognized diverse microbial community that likely effects microbial access and metabolism of soil substrates.

agroecosystem↗

DOE OSTI2018

Sterically controlled mechanochemistry under hydrostatic pressure

Mechanical stimuli can modify the energy landscape of chemical reactions and enable reaction pathways, offering a synthetic strategy that complements conventional chemistry. These mechanochemical mechanisms have been studied extensively in one-dimensional polymers under tensile stress using ring-opening and reorganization, polymer unzipping and disulfide reduction as model reactions. In these systems, the pulling force stretches chemical bonds, initiating the reaction. Additionally, it has been shown that forces orthogonal to the chemical bonds can alter the rate of bond dissociation. Furthermore, these bond activation mechanisms have not been possible under isotropic, compressive stress (that is, hydrostatic pressure). Here we show that mechanochemistry through isotropic compression is possible by molecularly engineering structures that can translate macroscopic isotropic stress into molecular-level anisotropic strain.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

LncRNA CCND2-AS1 promotes proliferation, migration, and invasion in papillary thyroid carcinoma

In decades, a lot of long non-coding RNAs (LncRNAs) have been proven to exert influences on tumorigenesis in vitro and in vivo. Many lncRNAs have been reported as effective therapeutic targets and biomarkers in various cancers. However, whether LncRNAs are associated with the progression of PTC remains largely unknown. In this study, we measured the expression of CCND2-AS1 in PTC cell lines by quantitative real-time polymerase chain reaction (qRT-PCR).We found that CCND2-AS1 expression was significantly over-expressed in PTC cell lines compared to normal thyroid epithelial cells. Gain-and loss-of-function experiments were performed to investigate the role of CCND2-AS1 in PTC cells. In vitro experiments, we proved that CCND2-AS1 knockdown in TPC1 significantly suppressed cell proliferation, migration, and invasion, while CCND2-AS1 overexpression in BCPAP had the opposite effects. Meanwhile, we also found that CCND2-AS1 could regulate N-cadherin and Vimentin expression, which may influence invasion and migration. Our findings indicate that the lncRNA CCND2-AS1 is a gene associated with PTC and might become a potential therapeutic target.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Phenomena of synchronized response in biosystems and the possible mechanism

Highlights: • An electrical communication mechanism is proposed to explain synchronization phenomena in biosystems. • The soliton-like electromagnetic pulses generated by the transmembrane ionic current are the carriers of information. • The softmaterial waveguide based on lipid membrane and fluids on both sides construct the transmission network. Phenomena of synchronized response is common among organs, tissues and cells in biosystems. We have analyzed and discussed three examples of synchronization in biosystems, including the direction-changing movement of paramecia, the prey behavior of flytraps, and the simultaneous discharge of electric eels. These phenomena and discussions support an electrical communication mechanism that in biosystems, the electrical signals are mainly soliton-like electromagnetic pulses, which are generated by the transient transmembrane ionic current through the ion channels and propagate along the dielectric membrane-based softmaterial waveguide network to complete synchronized responses. This transmission model implies that a uniform electrical communication mechanism might have been naturally developed in biosystem.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Nonthermal ice nucleation observed at distorted contact lines of supercooled water drops

Ice nucleation is the crucial step for ice formation in atmospheric clouds and therefore underlies climatologically relevant precipitation and radiative properties. Some progress has been made in understanding the roles of temperature, supersaturation, and material properties, but an explanation for the efficient ice nucleation occurring when a particle contacts a supercooled water drop has been elusive for over half a century. Here, we explore ice nucleation initiated at constant temperature and observe that mechanical agitation induces freezing of supercooled water drops at distorted contact lines. Results show that symmetric motion of supercooled water on a vertically oscillating substrate does not freeze, no matter how we agitate it. However, when the moving contact line is distorted with the help of trace amounts of oil or inhomogeneous pinning on the substrate, freezing can occur at temperatures much higher than in a static droplet, equivalent to ~1010 increase in nucleation rate. Several possible mechanisms are proposed to explain the observations. One plausible explanation among them, decreased pressure due to interface curvature, is explored theoretically and compared with the observational results quasiquantitatively. Indeed, the observed freezing-temperature increase scales with contact line speed in a manner consistent with the pressure hypothesis. Whatever the mechanism, the experiments demonstrate a strong preference for ice nucleation at three-phase contact lines compared to the two-phase interface, and they also show that movement and distortion of the contact line are necessary contributions to stimulating the nucleation process.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

Role of pyroptosis in normal cardiac response to calorie restriction and starvation

Highlights: • Moderate and severe caloric restriction exert different effect on cardiomyocytes. • Moderate caloric restriction alleviates the progression of pyroptosis. • Severe caloric restriction promotes the progression of pyroptosis. An unhealthy diet is a major risk factor for cardiac diseases. Most researches focus on high fat diet, little is known about the detrimental effects of starvation on heart.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Cancer stem cell-like population is preferentially suppressed by EGFR-TKIs in EGFR-mutated PC-9 tumor models

Highlights: • EGFR-TKIs strongly inhibited the β-catenin signal and decreased CSCs sorted out by SP cells. • The reduction of CSCs significantly reduced the migration capability. • Targeting β-catenin could be a potential strategy for EGFR-mutated NSCLC. Although the epidermal growth factor receptor (EGFR) and Wnt/β-catenin signaling systems synergistically regulate many essential developmental and regenerative processes in lung cancer, the mechanisms of their crosstalk remain poorly defined. Our study aimed to investigate an interaction between EGFR and the β-catenin signal.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Capacity Fading Mechanism of the Commercial 18650 LiFePO 4 -Based Lithium-Ion Batteries: An in Situ Time-Resolved High-Energy Synchrotron XRD Study

In this paper, in situ high-energy synchrotron XRD studies were carried out on commercial 18650 LiFePO 4 cells at different cycles to track and investigate the dynamic, chemical, and structural changes in the course of long-term cycling to elucidate the capacity fading mechanism. The results indicate that the crystalline structural deterioration of the LiFePO 4 cathode and the graphite anode is unlikely to happen before capacity fades below 80% of the initial capacity. Rather, the loss of the active lithium source is the primary cause for the capacity fade, which leads to the appearance of inactive FePO 4 that is proportional to the absence of the lithium source. Our in situ HESXRD studies further show that the lithium-ion insertion and deinsertion behavior of LiFePO 4 continuously changed with cycling. For a fresh cell, the LiFePO 4 experienced a dual-phase solid-solution behavior, whereas with increasing cycle numbers, the dynamic change, which is characteristic of the continuous decay of solid solution behavior, is obvious. Finally, the unpredicted dynamic change may result from the morphology evolution of LiFePO 4 particles and the loss of the lithium source, which may be the cause of the decreased rate capability of LiFePO 4 cells after long-term cycling.

18650 cell↗

DOE OSTI2017

First-principles investigation of metal-doped cubic BaTiO{sub 3}

Highlights: • Electronic properties of metal-doped cubic BaTiO{sub 3} are studied by DFT calculations. • Most transition-metal doping can effectively reduce the band gap of BaTiO{sub 3}. • The effective mass can be reduced by doping BaTiO{sub 3} with metals. • Substituting Ti with Fe or Mo could improve the photoelectric properties of BaTiO{sub 3}. - Abstract: The electronic properties of metal-doped cubic BaTiO{sub 3} have been investigated using first-principles calculations. Through systematic analysis on effects of various metals doping through substituting Ti with the main group, 3d and 4d transitions metal atoms, we show that most transition metal doping can effectively reduce the band gap of BaTiO{sub 3}. The partial density of states analysis indicates that different doping elements have different effects on the band-gap engineering. The effective mass of BaTiO{sub 3} before and after doping was further analyzed. And we found that the hole effective mass apparently decrease after Fe, Cu, Zn, Mo, and Ag doping, which could lead to increase of hole mobility and charge transfer enhancement. The calculation results showed that substituting Ti with Fe or Mo would be more effective for improving the photoelectric property of BaTiO{sub 3}. Our theoretical calculations provide useful insights and beneficial guidance into experimental study of BaTiO{sub 3} in the photoelectric applications.

36 MATERIALS SCIENCE↗