The solidification microstructure of Mg–Gd–Y–Zr alloy was investigated via an experimental study and cellular automaton (CA) simulation. In this study, step-shaped castings were produced, and the ...temperature variation inside the casting was recorded using thermocouples during the solidification process. The effects of the cooling rate and Zr content on the grain size of the Mg–Gd–Y–Zr alloy were studied. The results showed that the grain size decreased with an increase in the cooling rate and Zr content. Based on the experimental data, a quantitative model for calculating the heterogeneous nucleation rate was developed, and the model parameters were determined. The evolution of the solidification microstructure was simulated using the CA method, where the quantitative nucleation model was used and a solute partition coefficient was introduced to deal with the solute trapping in front of the solid–liquid (S/L) interface. The simulation results of the grain size were in good agreement with the experimental data. The simulation also showed that the fraction of the eutectics decreased with an increasing cooling rate in the range of 2.6–11.0 °C·s−1, which was verified indirectly by the experimental data.
Compacted loess is widely used as fills of road embankments in loess regions of northern China.Generally, densely-compacted loess can satisfy the requirements of embankment strength and ...postconstruction deformation. However, uneven subsidence, pavement cracks and other related damages can affect the integrity of loess subgrade after several years of operation,and even cause some hazards, especially in North China, where the strong freeze-thaw erosion occurs. In this study, cyclic freeze-thaw tests for both densely and loosely compacted loess samples were performed to determine the variation in engineering properties such as volume, void ratio, collapsible settlement,microstructure, and the related mechanisms were addressed. The experimental results showed that an obvious water migration and redistribution occurred within the samples during freeze-thaw cycles. Ice lenses and fissures could be identified in the upper frozen layers of the samples. After freeze-thaw cycles,the dry densities of the upper layers of samples changed significantly due to strong freeze-thaw erosion. The dry densities decreased for the dense sample and increased for the loose sample. It can be found that dense samples become loose, while loose samples became dense with the increasing number of freeze-thaw cycles. Their related void ratios changed reversely. Both void ratios tended to fall into a certain range, which verified the concept of a residual void ratio proposed by Viklander. The loosening process of densely compacted samples involves the formation of large pores, volume increase and density reduction as well as the related changes in mechanical properties because freeze-thaw cycles may be important contribution to problems of loess road embankments.Adverse effects of freeze-thaw cycles, therefore,should be taken into account in selecting loess parameters for the stability evaluation of road embankment in seasonally frozen ground regions.
Commercial computers based on electronic logic devices have brought great changes to the world. However, traditional electronic devices are suffering from numerous technical challenges in their ...attempts to continue to satisfy Moore’s law. All-optical logic devices, as promising successors to their electronic counterparts, have become a major focus of optics research. In this paper, we provide a review of current all-optical logic devices. The logic gates in these devices, which are described in the first part of the review, are divided into five categories based on the different principles used in their realization. Complex optical devices with various functions and reconfigurable devices are summarized in the next section. In the final part of this paper, we discuss some of the previous works on all-optical integrated chips with specific functions. This review will provide a complete technological roadmap for all-optical devices and aims to be helpful in possible future developments in this growing field.
As an advanced near-net shape technology, squeeze casting is an excellent method for producing high integrity castings. Numerical simulation is a very effective method to optimize squeeze casting ...process, and the interfacial heat transfer coefficient (IHTC) is an important boundary condition in numerical simulation. Therefore, the study of the IHTC is of great significance. In the present study, experiments were conducted and a "plate shape" aluminum alloy casting was cast in H13 steel die. In order to obtain accurate temperature readings inside the die, a special temperature sensor units (TSU) was designed. Six 1 mm wide and 1 mm deep grooves were machined in the sensor unit for the placement of the thermocouples whose tips were welded to the end wall. Each groove was machined to terminate at a particular distance (1, 3, and 6 mm) from the front end of the sensor unit. Based on the temperature measurements inside the die, the interfacial heat transfer coefficient (IHTC) at the metal-die interface was determined by applying an inverse approach. The acquired data were processed by a low pass filtering method based on Fast Fourier Transform (FFT). The feature of the IHTC at the metal-die interface was discussed.
Background At present, adenosine (AD) is the most widely used agents in fractional flow reserve (FFR) measurement but has the disadvantages of higher rate of complications including atrioventricular ...block. So it’s necessary to explore other stimulus equivalent to or better than AD in effects on FFR measurement with less complications and lower costs. Methods In 40 patients with 53 moderate coronary stenosis, intracoronary (IC) AD in 2 serial doses (A1: 40 μg; A2: 60 μg) was administered in the standard bolus to calculate FFR, followed by a repeat FFR measurement with IC Sodium Nitroprusside (SNP) in 3 serial doses (S1: 0.3 μg/kg; S2: 0.6 μg/kg; S3: 0.9 μg/kg). Results ➀ Target lesions were located in the left anterior descending (n = 24), left circumflex (n = 13) and right coronary artery (n = 16). The mean stenosis rate was 62.8 ± 8.6%. ➁ FFR value decreased significantly from 0.90 ± 0.05 at baseline to 0.83 ± 0.06, 0.82 ± 0.07, 0.83 ± 0.07, 0.81 ± 0.07 and 0.81 ± 0.07 in A1, A2, S1, S2 and S3(F = 16.877, P < 0.001). ➂ Systolic blood pressure decreased by 3.99%, 6.64%, 6.87%, 10.56% and 15.55% in A1, A2, S1, S2 and S3. ➃ Heart rate was increased by 2.01%, 0.84%, 1.23%, 1.34% and 3.11% in A1, A2, S1, S2 and S3. ➄ The mean time to peak value of FFR delayed in S1, S2 and S3 compared with A2 (F = 15.593, P➄ The mean duration of the plateau phase was longer in S1, S2 and S3 compared with A2 (F = 34.445, P P = 0.008). ➅ Immediate complications occurred in 15.1% of patients, including transient atrioventricular block (6 patients), chest pain (1 patient) and stomachache (1 patient) after the 60 μg dose of IC AD bolus was administered. No adverse events were found after 3 serial of doses IC SNP were used. (X2 = 8.171, P = 0.004). Conclusions Compared with IC AD, IC SNP has equivalent effects on FFR measurement as well as the advantage of lower rate of complications and cost. But duration of the plateau phase by IC SNP is twice as much by IC AD, and time to peak FFR value was delayed 50%.
Aim： The ubiquitin-proteasome system （UPS） and lysosome-dependent macroautophagy （autophagy） are two major intracellular pathways for protein degradation. Recent studies suggest that proteasome ...inhibitors may reduce tumor growth and activate autophagy. Due to the dual roles of autophagy in tumor cell survival and death, the effect of autophagy on the destiny of glioma cells remains unclear. In this study, we sought to investigate whether inhibition of the proteasome can induce autophagy and the effects of autophagy on the fate of human SHG-44 glioma cells.
Methods： The proteasome inhibitor MG-132 was used to induce autophagy in SHG-44 glioma cells, and the effect of autophagy on the survival of SHG-44 glioma cells was investigated using an autophagy inhibitor 3-MA. Cell viability was measured by MTT assay. Apoptosis and cell cycle were detected by flow cytometry. The expression of autophagy related proteins was determined by Western blot.
Results： MG-132 inhibited cell proliferation, induced cell death and cell cycle arrest at GJM phase, and activated autophagy in SHG-44 glioma cells. The expression of autophagy-related Beclin-1 and LC3-1 was significantly up-regulated and part of LC3-1 was converted into LC3-11. However, when SHG-44 glioma cells were co-treated with MG-132 and 3-MA, the cells became less viable, but cell death and cell numbers at G2/M phase increased. Moreover, the accumulation of acidic vesicular organelles was decreased, the expression of Beclin-1 and LC3 was significantly down-regulated and the conversion of LC3-11 from LC3-1 was also inhJbited.
Conclusion： Inhibition of the proteasome can induce autophagy in human SHG-44 glioma cells, and inhibition of autophagy increases cell death. This discovery may shed new light on the effect of autophagy on modulating the fate of SHG-44 glioma cells.
The research on the supramolecular hyperbranched polymers（SHPs） that combines the advantages of supramolecular polymer and hyperbranched architecture has attracted considerable interests in many ...applications. Here we demonstrate a simple approach to prepare POSS-embedded supramolecular hyperbranched polymers（POSS-SHPs） with varied morphology and size by controlling monomer concentration and mixed solvents. The SHPs formations can further transfer into the core-shell structured micelles by addition of competitive guests based on the double supramolecular driving forces.
Attrora-A kinase, a serine/threonine protein kinase, is a potential oncogene. Amplification and overexpression of Aurora-A have been found in several types of human tumors, including esophageal ...squamous cell carcinoma （ESCC）. It has been demonstrated that cells overexpressing Attrora-A are more resistant to cisplatin-induced apoptosis. However, the molecular mechanisms mediating these effects remain largely unknown. In this report, we showed that overexpression of Attrora-A through stable transfection of pEGFP-Aurora-A in human ESCC KYSE150 cells significantly promoted cell proliferation and inhibited cisplatin- or UV irradiation-induced apoptosis. Cleavages of caspase-3 and poly （ADPribose） polymerase （PARP） in Attrora-A overexpressing cells were substantially reduced after cisplatin or UV treatment. Furthermore, we found that silencing of endogenous Aurora-A kinase with siRNA substantially enhanced sensitivity to cisplatin- or UV-induced apoptosis in human ESCC EC9706 cells. In parallel, overexpression of Aurora-A potently upregulated the expression of Bcl-2. Moreover, the knockdown of Bcl-2 by siRNA abrogated the Aurora-A＇s effect on inhibiting apoptosis. Taken together, these data provide evidence that Aurora-A overexpression promoting cell proliferation and inhibiting apoptosis, suggesting a novel mechanism that is closely related to malignant phenotype and anti-cancer drugs resistance of ESCC cells.
The Arctic near-surface air temperatures are increasing more than twice as fast as the global average-a feature known as Arctic amplification （AA）. A modified AA index is constructed in this paper to ...emphasize the contrast of warming rate between polar and mid-latitude regions, as well as the spatial and temporal characteristics of AA and their influence on atmospheric circulation over the Northern Hemisphere. Results show that AA has a pronounced annual cycle. The positive or negative phase activities are the strongest in autumn and winter, the weakest in summer. After experiencing a remarkable decadal shift from negative to positive phase in the early global warming hiatus period, the AA has entered into a state of being enlarged continuously, and the decadal regime shift of AA in about 2002 is affected mainly by decadal shift in autumn. In terms of spatial distribution, AA has maximum warming near the surface in almost all seasons except in summer. Poleward of 20~N, AA in autumn has a significant influence on the atmospheric circulation in the following winter. The reason may be that the autumn AA increases the amplitude of planetary waves, slows the wave speeds and weakens upper-level zonal winds through the thermal wind relation, thus influencing surface air temperature in the following winter. The AA correlates to negative phase of the Arctic oscillation （AO） and leads AO by 0-3 months within the period 1979-2002. However, weaker relationship between them is indistinctive after the decadal shift of AA.
OBJECTIVESTo establish age estimation models of northern Chinese Han adults using cranial suture images obtained by CT and multiplanar reformation (MPR), and to explore the applicability of cranial ...suture closure rule in age estimation of northern Chinese Han population.METHODSThe head CT samples of 132 northern Chinese Han adults aged 29-80 years were retrospectively collected. Volume reconstruction (VR) and MPR were performed on the skull, and 160 cranial suture tomography images were generated for each sample. Then the MPR images of cranial sutures were scored according to the closure grading criteria, and the mean closure grades of sagittal suture, coronal sutures (both left and right) and lambdoid sutures (both left and right) were calculated respectively. Finally taking the above grades as independent variables, the linear regression model and four machine learning models for age estimation (gradient boosting regression, support vector regression, decision tree regression and Bayesian ridge regression) were established for northern Chinese Han adults age estimation. The accuracy of each model was evaluated.RESULTSEach cranial suture closure grade was positively correlated with age and the correlation of sagittal suture was the highest. All four machine learning models had higher age estimation accuracy than linear regression model. The support vector regression model had the highest accuracy among the machine learning models with a mean absolute error of 9.542 years.CONCLUSIONSThe combination of skull CT-MPR and machine learning model can be used for age estimation in northern Chinese Han adults, but it is still necessary to combine with other adult age estimation indicators in forensic practice.
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