Subnanoscale Ion Beam Modification-Assisted Smoothing of Heterostructure Surfaces.

Glass ceramic (GC) is the most promising material for objective lenses for extreme ultraviolet lithography that must meet the subnanometer precision, which is characterized by low values of high spatial frequency surface roughness (HSFR). However, the HSFR of GC is typically degraded during ion beam figuring (IBF). Herein, a developed method for constructing molecular dynamics (MD) models of GC was presented, and the formation mechanisms of surface morphologies were investigated. The results indicated that the generation of the dot-like microstructure was the result of the difference in the erosion rate caused by the difference in the intrinsic properties between ceramic phases (CPs) and glass phases (GPs). Further, the difference in the microstructure of the IBF surface under different beam angles was mainly caused by the difference in the two types of sputtering. Quantum mechanical calculations showed that the presence of interstitial atoms would result in electron rearrangement and that the electron localization can lead to a reduction in CP stability. To obtain a homogeneous surface, the effects of beam parameters on the heterogeneous surface were systematically investigated based on the proposed MD model. Then, a novel ion beam modification (IBM) method was proposed and demonstrated by TEM and GIXRD. The range of ion beam smoothing parameters that could effectively converge the HSFR of the modified surface was determined through numerous experiments. Using the optimized beam parameters, an ultrathin homogeneous modified surface within 3 nm was obtained. The HSFR of GC smoothed by ion beam modification-assisted smoothing (IBMS) dropped from 0.348 to 0.090 nm, a 74% reduction. These research results offer a deeper understanding of the morphology formation mechanisms of the GC surfaces involved in ion beam processing and may point to a new approach for achieving ultrasmooth heterostructure surfaces down to the subnanometer scale.

An Analysis of the Effect of Abrasive/Tool Wear on the Ductile Machining of Fused Silica from the Perspective of Stress.

Understanding the influence mechanism of abrasive/tool wear on machining is the key to realize high-efficiency ultra-precision machining of fused silica. To explore the effect of abrasive/tool wear on ductile machining, the smoothed particle hydrodynamics (SPH) cutting models with different edge radii are established. Through the analysis of equivalent rake angle, hydrostatic pressure, cutting force and maximum principal stress with the Flamant's formula, the influence of edge radii on ductile-brittle transition (DBT) is discussed for the first time. The simulation results show that when the edge radius increases from less to larger than the cutting depth, the equivalent rake angle changes from positive to negative, and the maximum hydrostatic pressure gradually increases, which is beneficial to promote the ductile processing. Meanwhile, with the rise of edge radius (i.e., abrasive/tool wear), both the cutting force and crack initiation angle increase, while the friction coefficient and normalized maximum principal decrease. When the value of normalized maximum principal stress exceeds 2.702, the crack in the workpiece begins to initiate, and its initiation angle calculated by the Flamant's formula is in good agreement with the simulation results as well as less than 50°. Finally, the nano-scratch experiment was carried out, and the material removal mechanism and friction coefficient f similar to the simulation were obtained, which further proved the accuracy of SPH model. This study is meaningful for understanding the effect of abrasive/tool wear on the removal mechanism of brittle materials and improving the quality and efficiency of cutting and grinding.

Exploration of China's net CO2 emissions evolutionary pathways by 2060 in the context of carbon neutrality.

In the context of global climate governance, as the biggest carbon emitter, China bears momentous responsibility for mitigating emissions. Especially after the carbon neutrality target is proposed, it is urgent for China to seek a feasible pathway to achieve net-zero carbon dioxide (CO2) emissions by 2060. With the aims of exploring the net-zero emission pathways, an integrated prediction model incorporating the extreme learning machine (ELM) network, the Aquila optimizer (AO) technique, and the Elastic Net (EN) regression method is constructed. Then the prediction model is employed to project CO2 emissions and forest carbon sinks during 2021-2060 under the nine designed scenarios. The simulation results reveal that China has the potential to achieve net-zero CO2 emissions by 2060 under the combined effects of reducing emissions and increasing forest carbon sinks. Specifically, the total CO2 emissions will be peaked at 11441 million tons CO2 (MtCO2) in 2029. The post-peak carbon reduction rate should be 8% per year, and the average annual forest carbon sink is required to be 209.45 TgC/year during 2021-2060. In addition, in accordance with the optimal carbon neutrality pathway, the GDP per capita growth rate should be maintained at 5.5% during the period of 2021-2030, China's urbanization rate should be increased to 72% in 2030, and the total energy consumption should be limited to a peak value of 6000 million tons of coal equivalent (Mtce) in 2030.

Hydrostatic pressure stabilizes HIF­1α expression in cancer cells to protect against oxidative damage during metastasis.

The tissue microenvironment is known to play a pivotal role in cancer metastasis. Interstitial fluid hydrostatic pressure generally increases along with the rapid growth of malignant tumors. The aim of the present study was to investigate the role and relevant mechanism of elevated hydrostatic pressure in promoting the metastasis of cancer cells. Using a commercial device, Lewis lung cancer (LLC) cells were exposed to 50 mmHg hydrostatic pressure (HP) for 24 h. The survival time and morphology of the cells did not notably change; however, the results from a PCR array revealed the upregulation of numerous metastasis­promoting genes (Hgf, Cdh11 and Ephb2) and the downregulation of metastasis suppressing genes (Kiss1, Syk and Htatip2). In addition, compared with that in the control, the cells which had undergone exposure to 50 mmHg HP showed significantly higher protein expression level of HIF­1α and the antioxidant enzymes, SOD1 and SOD2, as well as improved tolerance to oxidative stress (P<0.05 vs. control). Following an intravenous injection of the LLC cells into healthy mice, to induce lung metastasis, it was found that the exposure of the LLC cells to 50 mmHg HP for 24 h, prior to injection into the mice, resulted in higher cell survival/retention in the lungs 24 h later and also resulted in more metastatic tumor lesions 4 weeks later (P<0.05 vs. control). Further investigation is required to confirm the molecular mechanism; however, the results from the present study suggested that elevated interstitial fluid HP in malignant tumors may promote the metastasis of cancer cells by stabilizing HIF­1α expression to defend against oxidative damage.

The semi-centennial timescale dynamic assessment on carbon emission trajectory determinants for Hebei Province within the New Normal pattern shock.

New normal development pattern has already been experiencing in China since the rate of economics slowing down recent years. This new development circumstance requires targeted and adapted policy instruments as well as mitigation measures to facilitate to achieve carbon emission peak around 2030. In the context of the new normal pattern, its advancement effectiveness that boosting on carbon emission trajectory is calculated by three combination models over a semi-centennial time scales ranging from 1985 to 2035 in this study. Hebei province is estimated as the empirical case for exploring the concrete response due to its critical status. Carbon emission trajectory is revealed from both historical and future perspectives. Historical trajectory reflects the changing trend of carbon emission over time spans since 1985 and before which new normal pattern occurred. On the converse, future trajectory projects the vary orientation of carbon emission between the period around new normal occurred and up to 2035. The carbon emission trajectory is separated into historical trajectory and future trajectory taking the initial time of the New Normal period as the dividing boundary. The results show that, the peaking time for Hebei province would be appeared at 2022, 2024, and 2026 with the peaking level of 226.78, 238.22, and 250.95 million tons, respectively. A lower increasing rate of 7% for GDP, a gradually decreasing proportion of the secondary industry ranging from 44.99% by 2020 to 37.9% by 2030, and a moderate growing magnitude for energy consumption restrained beyond 371.15 Mtce towards 2030 is identified as the optimal pathway for reaching carbon emission peak.

Enhanced Estrogenic Activity of Soybean Isoflavones by Coadministration of Liuwei Dihuang Pills in Ovariectomized Rats.

Soybean isoflavones are beneficial for treating hormone-related diseases. Simultaneous consumption of soybean isoflavones and Liuwei Dihuang pills (LWPs) is effective for treating perimenopausal period syndrome. However, why the combination of isoflavones and LWPs is more effective than ingestion of each component alone remains unknown. Here, we show that enhanced estrogenic activities would appear when the ovariectomized rats were fed with a soybean diet in combination of LWPs treatment. Our further studies explored enhancements of Lactobacillus (19-fold) and Bifidobacterium (12-fold) contents in the intestine of rat and 1.84-fold higher intestinal ß-glucosidase activity in LWPs treatment group compared with the control group. As a result, steady-state concentrations of genistein (1.20-fold), daidzein (1.36-fold), and equol (1.43-fold) in serum were significantly elevated in the combination group compared with the soybean alone group. The results present the first evidence of the mechanism of enhanced estrogenic activity of dietary soybean isoflavones in combination with LWPs. Our study indicates that alterations of gut bacteria after LWPs treatment play a key role in the enhanced estrogenic effect of dietary soybean, suggesting a direct relationship between dietary soybean, LWPs, and gut flora.