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Wang, Cong

Publications and source records attributed to Wang, Cong.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Influence of TiH{sub 2} on Interfacial Reaction Features Between Cubic Boron Nitride and Cu-Sn-Ti Active Filler Metals

Cubic boron nitride (CBN) grains are brazed by Cu-Sn-Ti filler metal in vacuum at 1223 K. Wetting behaviors, reaction layer features, and elemental distribution characteristics have been systematically investigated through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results show that when the TiH{sub 2} content is 5 wt pct, virtually no sharp-edged, partially coated, and uncoated CBN grains can be observed, indicating that adequate wetting could be achieved. Moreover, a continuous reaction layer with uniform thickness (1.30 μm) consisting of TiN, TiB{sub 2}, and TiB is obtained, which indicates that large numbers of TiN, TiB{sub 2}, and TiB compounds could have been formed at the interface. However, when the TiH{sub 2} content exceeds 5 wt pct, the thickness of the reaction layer is no longer significantly expanding and excessive Ti present in the matrix will lower the volume percentage of Cu{sub 3}Sn{sub 1} phase, which will reduce the bonding strength of the brazing samples. Wear tests indicate that the minimum weight loss also occurs at 5 wt pct TiH{sub 2}.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Unexpected Charpy Impact Toughness Spike of 1.25Cr-0.5Mo Steel After Simulated Postweld Heat Treatment

The present study elaborates on the effect of simulated postweld heat treatment (SPWHT) on microstructure and mechanical property variations of 1.25Cr-0.5Mo steel. With the increase in SPWHT holding time, lath ferrite tends to morph into blocky ferrite, and carbides aggregate along grain boundaries. Although tensile strength keeps decreasing, Charpy impact toughness undergoes a spike, followed by a sharp decrease. Such an interesting phenomenon is explained by the competition between high-angle grain boundary population and carbide segregation, and bodes well to the pressure vessel industry for optimized PWHT.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Long-Term Warming in Alaska Enlarges the Diazotrophic Community in Deep Soils

Tundra ecosystems are typically carbon (C) rich but nitrogen (N) limited. Since biological N 2 fixation is the major source of biologically available N, the soil N 2 -fixing (i.e., diazotrophic) community serves as an essential N supplier to the tundra ecosystem. Recent climate warming has induced deeper permafrost thaw and adversely affected C sequestration, which is modulated by N availability. Therefore, it is crucial to examine the responses of diazotrophic communities to warming across the depths of tundra soils. Herein, we carried out one of the deepest sequencing efforts of nitrogenase gene ( nifH ) to investigate how 5 years of experimental winter warming affects Alaskan soil diazotrophic community composition and abundance spanning both the organic and mineral layers. Although soil depth had a stronger influence on diazotrophic community composition than warming, warming significantly ( P < 0.05) enhanced diazotrophic abundance by 86.3% and aboveground plant biomass by 25.2%. Diazotrophic composition in the middle and lower organic layers, detected by nifH sequencing and a microarray-based tool (GeoChip), was markedly altered, with an increase of α-diversity. Changes in diazotrophic abundance and composition significantly correlated with soil moisture, soil thaw duration, and plant biomass, as shown by structural equation modeling analyses. Therefore, more abundant diazotrophic communities induced by warming may potentially serve as an important mechanism for supplementing biologically available N in this tundra ecosystem. IMPORTANCE With the likelihood that changes in global climate will adversely affect the soil C reservoir in the northern circumpolar permafrost zone, an understanding of the potential role of diazotrophic communities in enhancing biological N 2 fixation, which constrains both plant production and microbial decomposition in tundra soils, is important in elucidating the responses of soil microbial communities to global climate change. A recent study showed that the composition of the diazotrophic community in a tundra soil exhibited no change under a short-term (1.5-year) winter warming experiment. However, it remains crucial to examine whether the lack of diazotrophic community responses to warming is persistent over a longer time period as a possibly important mechanism in stabilizing tundra soil C. Through a detailed characterization of the effects of winter warming on diazotrophic communities, we showed that a long-term (5-year) winter warming substantially enhanced diazotrophic abundance and altered community composition, though soil depth had a stronger influence on diazotrophic community composition than warming. These changes were best explained by changes in soil moisture, soil thaw duration, and plant biomass. These results provide crucial insights into the potential factors that may impact future C and N availability in tundra regions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Overcharge investigation of large format lithium-ion pouch cells with Li(Ni 0.6 Co 0.2 Mn 0.2 )O 2 cathode for electric vehicles: Thermal runaway features and safety management method

The overcharge-induced thermal runaway features of large format commercial lithium-ion batteries with Li(Ni 0.6 Co 0.2 Mn 0.2 )O 2 (NCM622) cathode for electric vehicles under different current rates (C-rates) have been systematically studied at ambient temperature. The overcharge process is characterized as four stages. The temperature rise and the maximum temperature of the battery surface don't increase in proportion to the applied C-rates. However, with the increase of C-rates, the crest voltage of voltage curve rises linearly. When the voltage reaches approximately 5.1 V, a new voltage plateau appears in the cases below 2C. It is not sufficient that the temperature sensor is placed only near the terminal tab for most battery packs of EVs. In addition, the accumulated heat analysis demonstrates that side reactions dominate the temperature rise and contribute to most of the accumulated heat before thermal runaway. To mitigate the impact of overcharge and avoid the thermal runaway risk, a safety management method is proposed. Furthermore, the sharp drop in voltage before thermal runaway also provides a feasible approach to forewarn the users of the impending risk. These results are important for building safer batteries and providing information for the safety monitoring function of the battery management system (BMS).

25 ENERGY STORAGE↗
DOE OSTI2018

Microstructure and Performance of Nano-WC Particle-Strengthened Ni Coatings by Electro-brush Plating

Nano-WC particle-strengthened Ni composite coatings were prepared by electro-brush plating. A series of artificial neural network models was developed for the analysis and prediction of the coating performance. The microstructure and phase structure were studied with SEM, XRD and EDS. Nano-WC particles as the hard phase were distributed evenly and dispersed in the coatings, which was conducive to the hardness enhancement of the coatings. Additionally, nano-WC particles as microballs inserted in the coatings could reduce the friction when wear of the coating surface occurred. Furthermore, the addition of nano-WC particles delayed the time of crack initiation and propagation in the coatings, which increased the service lifetime when they worked in a thermal shock environment.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

In Situ Observation of the Nucleation and Growth of Ferrite Laths in the Heat-Affected Zone of EH36-Mg Shipbuilding Steel Subjected to Different Heat Inputs

The nucleation and growth behaviors of ferrite laths in the heat-affected zone (HAZ) of EH36-Mg shipbuilding steel with different heat inputs were observed in situ by high-temperature confocal scanning laser microscope (CSLM). It was found that ferrite laths prefer to nucleate on the surface of inclusions instead of grain boundaries under the heat input of 120 kJ/cm, while FSPs are easier to form in 210 kJ/cm due to a significantly reduced cooling rate.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fabrication of In2O3/TiO2 nanotube arrays hybrids with homogeneously developed nanostructure for photocatalytic degradation of Rhodamine B

Highlights: • A new class of plate-like In{sub 2}O{sub 3}/TNAs photocatalyst is successfully fabricated. • The obtained In{sub 2}O{sub 3}/TNAs hybrid presents a well-aligned nanotubular structure. • In{sub 2}O{sub 3} particles are dispersed homogeneously on TNAs without blocking the nozzles. • In{sub 2}O{sub 3}/TNAs hybrid shows a much enhanced Rhodamine B degradation efficiency. • In{sub 2}O{sub 3}/TNAs hybrid demonstrates an excellent recycling capability. - Abstract: To enhance the photocatalytic recycling capability of the TiO{sub 2}-based photocatalysts, a new kind of plate-like In{sub 2}O{sub 3}/TiO{sub 2} nanotube array (TNA) hybrids is fabricated herein by constructing TNAs via an anodization method followed by doping In{sub 2}O{sub 3} via a solvothermal method. The obtained In{sub 2}O{sub 3}/TNA hybrid demonstrates a well-aligned nanotubular structure with homogeneous dispersion of In{sub 2}O{sub 3} nanoparticles. It shows a much higher degradation rate of 77% after 2 h compared to TNA (37%). In addition, the plate-like feature endows the photocatalysts with an excellent recycling capability. These superior photocatalytic degradation performances can be ascribed to the following factors: (1) the enhanced light absorption ability and efficient separation of photoexcited electron-hole pairs derived from the formation of the heterostructure between the interface of TiO{sub 2} and In{sub 2}O{sub 3}; (2) the efficient transport of reactant molecules provided by the well-defined TNAs and the homogeneous distribution of the In{sub 2}O{sub 3} nanoparticles without blocking the nanotubes.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

H-D Exchange of Simple Aromatics as a Measure of Brønsted-Acid Site Strengths in Solids

The relative Brønsted-acid strengths of H-[Al]ZSM-5, H-[Fe]ZSM-5, H-[B]ZSM-5, silicalite, P-SPP, tungstated zirconia, ZrO2, and γ-Al2O3 were studied using H-D exchange with toluene and chlorobenzene. Temperature programmed desorption (TPD) of toluene-h8 and chlorobenzene-h5 from the deuterated forms of H-[Al]ZSM-5, H-[Fe]ZSM-5, and P-SPP demonstrated that the temperature at which H-D exchange rates become significant change with the proton affinity of the aromatic molecule and the strength of the Brønsted sites. The steady-state, gas-phase reaction between D2O and the aromatic molecules were consistent with the TPD results and allowed the Brønsted-acid site strengths to be ordered as follows: H-[Al]ZSM-5 > H-[Fe]ZSM-5 > tungstated zirconia > P-SPP > H-[B]ZSM-5. H-D exchange was also observed at high temperatures with ZrO2 and γ-Al2O3 but it appears that the reaction mechanism with these Lewis acids is different because reaction with toluene and chlorobenzene occur at nearly the same temperature. It is suggested that the H-D exchange reaction with simple aromatic molecules is a useful way to probe Brønsted acidity in solids

bio-inspired↗
DOE OSTI2018

4-Amino-2-Trifluoromethyl-Phenyl Retinate induced leukemia cell differentiation by decreasing eIF6

4-Amino-2-Trifluoromethyl-Phenyl Retinate (ATPR), an all-trans retinoic acid (ATRA) derivative, possesses the ability to relief several carcinoma. Here, we explored the potential molecular mechanism of eukaryotic translation initiation factor 6 (eIF6) in ATPR-induced leukemia cell differentiation. Our research showed that ATPR could inhibit cell proliferation and promote cell differentiation in several leukemia cell lines. Besides, ATPR remarkably reduced the expression of eIF6 in vitro. Interestingly, the reduction of eIF6 contributed to restraining proliferation of K562 cells by inhibiting CyclinD1, C-myc and blocking cell cycle, as well as promoting differentiation of K562 cells by increasing the expression of C/EBPε, cell surface antigen CD11b and inducing renal-shrinkage of nuclear. Furthermore, the over-expression of eIF6 restrained the effects of ATPR on cell proliferation and maturation in K562 cells. In Addition, Notch1/CBF-1 signal activated by Chrysin could increase expression of eIF6 and restrain the differentiation in ATPR-induced K562 cells. Taken together, all above results indicated that ATPR induced differentiation of leukemia cells by decreasing eIF6 through Notch1/CBF-1 signal, which might exert an innovative treatment for leukemia.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

MicroRNA-128 contributes to the progression of gastric carcinoma through GAREM-mediated MAPK signaling activation

Gastric carcinoma (GC) represents the most common malignant cancer and the second leading cause of cancer death worldwide. However, the molecular mechanisms and biological progression of GC remain unknown. In this study, we found that miR-128 is a critical tumor suppressor that is downregulated in GC patients and GC cells and that GAREM is a direct downstream target of miR-128. Overexpression of miR-128 in HGC-27 and MKN-45 cells resulted in suppressed cell growth and promoted cell apoptosis through a GAREM-dependent mechanism. Moreover, the precise mechanisms underlying the antitumor effect of miR-128 in GC are at least partially due to suppressing activation of the MAPK signaling pathway, induced by suppressing GAREM expression. This study is the first to demonstrate that the miR-128-GAREM-MAPK signaling pathway forms a critical feedback loop and mediates GC development, and these findings might demonstrate a potential therapeutic strategy for GC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Multiphase Optimal and Non-Singular Power Flow by Successive Linear Approximations

We propose an optimal power flow method for multiphase power systems. The method works for both radial and meshed networks, and is able to accommodate different types of load/source connections such as wye, delta, and combination thereof. Moreover, the method generates a sequence of nonsingular points (i.e., associated with non-singular power-flow Jacobian) in the electrical state space and a corresponding sequence of power injections, which can be used in real-time control settings. Under certain conditions, the sequences attain the local minimum. The method has been tested using several typical networks, including the IEEE 37-bus and 123-bus test feeders.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Multiphase Optimal and Non-Singular Power Flow by Successive Linear Approximations: Preprint

We propose an optimal power flow method for multiphase power systems. The method works for both radial and meshed networks, and is able to accommodate different types of load/source connections such as wye, delta, etc. Moreover, the method generates a sequence of non-singular points in the electrical state space and a corresponding sequence of power injections, which can be used in real-time control settings. Under certain conditions, the sequences attain the local minimum. The method has been tested using several typical networks, including the IEEE 37-bus and 123-bus test feeders.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Mechanistic Study of the Direct Hydrodeoxygenation of m -Cresol over WO x -Decorated Pt/C Catalysts

In this report hydrodeoxygenation (HDO) of m-cresol to produce toluene over carbon-supported Pt and Pt-WOx catalysts was studied. In stark contrast to Pt/C that exhibits only modest selectivity and low stability for this reaction, Pt-WOx/C was found to be unusually active and selective to toluene with greater than 94% selectivity to this product while exhibiting little to no deactivation under a wide range of reaction conditions. Reactivity studies in combination with density functional theory (DFT) calculations for the adsorption and reaction of m-cresol on structurally optimized WOx-decorated Pt(111) structures indicate that the HDO reaction on Pt-WOx/C proceeds via a direct hydrogenolysis of the C–O bond in m-cresol adsorbed on oxygen vacancy (or redox) sites on WOx species. The DFT results also indicate that Pt helps stabilize the WOx film while facilitating oxygen vacancy formation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Detecting Outliers in Network Transfers with Feature Extraction

Reliable file transfers are essential for successful science computations and experiments that need large complex data files to be moved across long distances. Networks use protocols such as TCP and UDP to support file transfers, and their performance degrades under packet losses and duplications, thereby adversely affecting science applications. Hence, scientists and engineers often monitor network statistics to find and repair network problems that cause such degradations.Outliers or anomalies can be detected using statistical and machine learning methods that highlight abnormal behaviors. However, without knowing what is normal, it is very difficult and subjective to determine the anomalies. In this paper, we investigate statistical and machine learning approaches to extract unknown or unsupervised features from TCP and perfSONAR data sets, with the aim to identify anomalies such as packet loss, duplication and retransmission sequencing that affect file transfer performance. Simple statistical and feature extraction methods (e.g. PCA) have shown that detecting anomalies is simpler if labeled data sets of normal behavior are available. While perfSONAR logs record losses,they do not detect duplications and reordering. We show that PCA applied to TCP statistics is able to determine abnormal behavior in the above cases. In particular, our results show that simple feature extraction techniques provide building blocks for more advanced network monitoring tools that can quickly flag anomalies using simple measurements, thereby helping to build confidence in file transfer reliability.

Rao, Nageswara S.↗
DOE OSTI2018

Orai1 downregulation impairs lymphocyte function in type 2 diabetes mellitus

Highlights: • Diabetes can affect immune function, increasing the risk of various infections in patients. • Changes in Ca{sup 2+} signal in diabetic lymphocytes and its underlined mechanism(s) are not clear. • The results demonstrate a reduced store-operated Ca{sup 2+} entry (SOCE) though downregulation of Orai1 expression. • This study provides additional insight into the disordered immune function in T cells. It has been suggested that diabetes is associated with immune dysfunction, in which Ca{sup 2+} signaling malfunction in lymphocyte may contributes most. However, the pattern of the Ca{sup 2+} signal disorder and the mechanism(s) that explains the change are unclear. Here, in this study we aimed to investigate possible changes and mechanism(s) accounting for the internal Ca{sup 2+} signals in diabetic T lymphocyte upon stimulation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

An Integrated Study on the Evolution of Inclusions in EH36 Shipbuilding Steel with Mg Addition: From Casting to Welding

Inclusion evolution behaviors, in terms of composition, size, and number density, and associated influence on the microstructures of the as-cast slabs, rolled plates, and simulated welded samples of plain EH36 and EH36-Mg shipbuilding steels have been systematically investigated. The results indicate that the inclusions in the as-cast plain EH36 are almost Al-Ca-S-O-(Mn) complex oxides with sizes ranging from 1.0 to 2.0 μm. After Mg addition, a large amount of individually fine MnS precipitates and Mg-containing Ti-Al-Mg-O-(Mn-S) complex inclusions are generated, which significantly refine the microstructure and are conducive to the nucleation of acicular ferrite in the rolled and welded sample. Moreover, after rolling and welding thermal simulation, the number of individual MnS decreases gradually due to its precipitation on the surface of Ti-Al-Mg-O oxides.

36 MATERIALS SCIENCE↗