Doping enables the effective tuning of the properties of semiconductor nanocrystals (NCs). In this paper, germanium (Ge) NCs are doped with boron (B) in nonthermal plasma. It is shown that B atoms ...prefer residing at/near the NC surface, rather than in the NC core. The surface state of Ge NCs is modified by the B doping. The oxidation of B-doped Ge NCs is not as serious as that of undoped Ge NCs. Devices based on B-doped Ge-NC films cast from the dispersion of B-doped Ge NCs have been fabricated. It is shown that the electrical conduction of the B-doped Ge-NC films is closely related to the doping level of B.
Recently, the first ever 100 s long, steady-state H-mode discharge with good control of impurities, core and edge MHD stabilities, and heat exhaust was demonstrated in the Experimental Advanced ...Superconducting Tokamak (EAST) using the ITER-like (International Tokamak Experimental Reactor) tungsten upper divertor. Using both radio frequency (RF) power and neutral beam injection (NBI) heating, EAST has demonstrated fully non-inductive scenarios with an extension of fusion performance at high density and low rotation: βP ∼ 2.5, βN ∼ 2.0, H98,y2 ∼ 1.2, bootstrap current fraction fBS ∼50% at q95 ∼ 6.8. With pure RF power heating, plasmas have been maintained for up to 21 s (over 40 times the current relaxation time) with zero loop voltage and small edge localized modes (ELMs) at high density (ne/nGW ∼ 0.6-0.8), βP ∼ 2.0, βN ∼ 1.6, and ƒBS ∼47%. Experimental investigations show how plasma current profiles, turbulent transport and radiation properties self-consistently evolve toward fusion relevant steady state conditions. Modeling and physics experiments have confirmed the synergistic effects between electron cyclotron heating (ECH) and low hybrid wave (LHW), where ECH enhances the heating and current drive from LHW injection, enabling fully non-inductive operation at higher density. Small/no ELMs facilitate the RF power coupling in the H-mode phase and reduce divertor erosion. A low tungsten concentration was observed at high βP with a hollow profile in the core. Reduction of the peak divertor heat flux with frad of up to 40% was compatible with the high βP scenario by using active radiation feedback control. With features such as dominant electron heating, zero/low NBI torque and an ITER-like tungsten divertor, fully non-inductive high-performance experiments on EAST offer unique contributions towards the succesful operation of ITER and CFETR (the Chinese Fusion Engineering Testing Reactor).
HeLa cells were exposed to formaldehyde and its metabolic derivatives, methanol, formic acid, and acetaldehyde, to investigate that the toxicity of formaldehyde is not caused by the chemical group. ...After 1 h of treatment with formaldehyde, mitochondrial assays showed that low concentrations (e.g. 10 μmol/L) of formaldehyde promoted growth of the HeLa cells, while higher concentrations (e.g. ≥62.5 μmol/L) inhibited cell growth; while all four chemicals at a concentration of 125 μmol/L affected cell growth, formaldehyde affected the largest. Reactive oxygen species concentration increased with the concentration of the exposure chemical. The endogenous formaldehyde content increased the most in the formaldehyde group, but in other three groups, it did not increase as the exposure concentration increased. Expression of dehydrogenase (formaldehyde dehydrogenase (FDH)) in the formaldehyde (10.40) and methanol (10.60) groups increased significantly compared with the control (1), while it was similar to the control in formic acid (0.90) and acetaldehyde (1.10) groups. Our results suggest that formaldehyde could affect cell activity and even enter cells. Exposure to formaldehyde changes the endogenous formaldehyde concentration in cells within 24 h, and this induces expression of FDH for formaldehyde degradation to maintain the formaldehyde balance. The toxicity of formaldehyde is not caused by the carbon atoms in the aldehyde, hydroxyl, or carboxyl groups. Formaldehyde is hypothesized to be an important signaling molecule in the regulation of cell growth and maintenance of the endogenous formaldehyde level.
The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two ...types of plasma disruptive discharges have been investigated for similar equilibrium parameters: one with a distinct stage of a small central temperature collapse (Formula: see text 5-10%) around 1 millisecond before the thermal quench (TQ), while the other without. For both types, the TQ phase is preceded by a rotating 2/1 tearing mode, and it is the development of the cold bubble from the inner region of the 2/1 island O-point along with its inward convection that causes the massive energy loss. In addition, the micro-scale turbulence, including magnetic fluctuations and density fluctuations, increases before the small collapse, and more significantly towards the TQ. Also, temperature fluctuations measured by electron cyclotron emission imaging enhances dramatically at the reconnection site and expand into the island when approaching the small collapse and TQ, and the expansion is more significant close to the TQ. The observed turbulence enhancement near the X-point cannot be fully interpreted by the linear stability analysis by GENE. Evidences suggest that nonlinear effects, such as the reduction of local Formula: see text shear and turbulence spreading, may play an important role in governing turbulence enhancement and expansion. These results imply that the turbulence and its interaction with the island facilitate the stochasticity of the magnetic flux and formation of the cold bubble, and hence, the plasma disruption.
Accurate and fast thermal estimation is important for the runtime thermal regulation of modern microprocessors due to excessive on-chip temperatures. However, due to the nonlinear relationship ...between the leakage power and temperature, full-chip thermal estimation methods suffer slow speed and scalability issue when the increasing static leakage power is considered. In this work, we propose a new fast leakage-aware full-chip thermal estimation method. Unlike traditional methods, which use iteration to handle the leakage-temperature nonlinearity dependency issue, the new method applies a dynamic linearization algorithm, which adaptively transforms the original nonlinear thermal model into a number of local linear thermal models. In order to further improve the thermal estimation efficiency, a specially-designed adaptive model order reduction method is integrated into the thermal estimation framework to generate local compact thermal models. Our numerical results show that the new method is able to accurately estimate full-chip transient temperature distribution by fully considering the nonlinear leakage-temperature dependency with fast speed. On different chips with core number ranging from 9 to 36, it achieved 85x to 589x speedup in average against traditional iteration based method, with average thermal estimation error to be around 0.2°C.
Porous titanium with appropriate surface treatments can be osteoinductive. To investigate the effect of surface treatments of porous titanium on the attachment and differentiation of mesenchymal stem ...cells (MSCs), two kinds of surface microstructured porous titaniums, H
2
O
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/TaCl
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treated one (HTPT), and H
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O
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/TaCl
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and subsequent simulated body fluid (SBF) treated one (STPT) were fabricated, and non-treated one (NTPT) was used as control. The morphology, specific surface area (SSA), pore distribution and mechanical strength of these materials were characterized respectively, and the results showed that H
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O
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/TaCl
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treatment led to a significant increase in both SSA and micropores of HTPT, and the further SBF immersion resulted in the formation of a layer of bone-like apatite on the surface of STPT. Although the surface treatments had a little negative impact on the compressive strength and elasticity modulus of porous titanium, the mechanical strength of HTPT or STPT was enough for the bone defect repair of the load-bearing sites. The protein adsorption and cell adhesion experiments confirmed that the microstructured surface notably enhanced porous titanium’s protein binding capacity and promoted MSCs adhesion on the surface. More importantly, cell differentiation experiments proved that the microstructured surface evidently elevated the osteoblastic gene expressions of MSCs compared to NTPT. The enhanced biological effect by the surface treatments was more robust on STPT. Therefore, our results suggest that the microstructured surface has great potential for promoting MSCs differentiation towards osteoblasts, giving excellent support for the osteoinduction of porous titanium with appropriate surface treatments.
A non weldable Ni-based DD98 superalloy was manufactured by direct laser deposition (DLD). The as-built samples show a heterogeneous microstructure along the build direction, which is associated with ...energy input. High energy input results in the formation of columnar grains with very well aligned to the build direction. However, a cluster of voids preferentially distributes along columnar grain boundary, leading to poor ductility (e.g., ∼2.3% elongation) of the deposit as its strain direction is perpendicular to the build direction. Fine dendrite and γ′ precipitate are observed in the sample fabricated by low energy input, which is associated with fast cooling rate after solidification. Secondary phases excluding γ′, such as MC carbide and HfO2 are observed in dendrite and interdendritic regions.
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