Influence of introducing Zr,Ti,Nb and Ce elements on externally solidified crystals and mechanical properties of high-pressure die-casting Al–Si alloy

High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated die-castings.Herein,the development of non-heat treatment Al alloys is becoming the hot topic.In addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of castings.To achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and Ce.Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation.Our results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased porosity.Meanwhile,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical properties.Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.

Nano-scale Reinforcements and Properties of Al-Si-Cu Alloy Processed by High-Pressure Torsion

To improve the comprehensive mechanical properties of Al-Si-Cu alloy,it was treated by a high-pressure torsion process,and the effect of the deformation degree on the microstructure and properties of the Al-Si-Cu alloy was studied.The results show that the reinforcements(β-Si andθ-CuAl_(2)phases)of the Al-Si-Cu alloy are dispersed in theα-Al matrix phase with finer phase size after the treatment.The processed samples exhibit grain sizes in the submicron or even nanometer range,which effectively improves the mechanical properties of the material.The hardness and strength of the deformed alloy are both significantly raised to 268 HV and 390.04 MPa by 10 turns HPT process,and the fracture morphology shows that the material gradually transits from brittle to plastic before and after deformation.The elements interdiffusion at the interface between the phases has also been effectively enhanced.In addition,it is found that the severe plastic deformation at room temperature induces a ternary eutectic reaction,resulting in the formation of ternary Al+Si+CuAl_(2)eutectic.

Experimental and Finite Element Analysis of Corroded High-Pressure Pipeline Repaired by Laminated Composite

Repairs of corroded high-pressure pipelines are essential for fluids transportation under high pressure.One of the methods used in their repairs is the use of layered composites.The composite used must have the necessary strength.Therefore,the experiments and analytical solutions presented in this paper are performed according to the relevant standards and codes,including ASME PCC-2,ASME B31.8S,ASME B31.4,ISO 24817 and ASME B31.G.In addition,the experimental tests are replicated numerically using the finite element method.Setting the strain gauges at different distances from the defect location,can reduce the nonlinear effects,deformation,and fluctuations due to the high pressure.The direct relationship between the depth of an axial defect and the stress concentration is observed at the inner side edges of the defect.Composite reparation reduces the non-linearities related to the sharp variation of the geometry and a more reliable numerical simulation could be performed.

CO_(2)high-pressure miscible flooding and storage technology and its application in Shengli Oilfield,China

There are various issues for CO_(2)flooding and storage in Shengli Oilfield,which are characterized by low light hydrocarbon content of oil and high miscible pressure,strong reservoir heterogeneity and low sweep efficiency,gas channeling and difficult whole-process control.Through laboratory experiments,technical research and field practice,the theory and technology of CO_(2)high pressure miscible flooding and storage are established.By increasing the formation pressure to 1.2 times the minimum miscible pressure,the miscibility of the medium-heavy components can be improved,the production percentage of oil in small pores can be increased,the displacing front developed evenly,and the swept volume expanded.Rapid high-pressure miscibility is realized through advanced pressure flooding and energy replenishment,and technologies of cascade water-alternating-gas(WAG),injection and production coupling and multistage chemical plugging are used for dynamic control of flow resistance,so as to obtain the optimum of oil recovery and CO_(2)storage factor.The research results have been applied to the Gao89-Fan142 in carbon capture,utilization and storage(CCUS)demonstration site,where the daily oil production of the block has increased from 254.6 t to 358.2 t,and the recovery degree is expected to increase by 11.6 percentage points in 15 years,providing theoretical and technical support for the large-scale development of CCUS.

Enhanced mechanical and electrical properties of multi-walled carbon nanotubes reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites via high-pressure torsion

In order to achieve combined mechanical and electrical properties,multi-walled carbon nanotubes(MWCNTs)reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites were further processed by high-pressure torsion(HPT).The maximum microhardness values of central and edge from the composites with 1 wt.%MWCNTs reached HV 130.0 and HV 363.5,which were 43.9%and 39.5%higher than those of the original samples,respectively.With the same content of MWCNTs,its electrical conductivity achieved 3.42×10^(7) S/m,which was increased by 78.1%compared with that of original samples.The synergistic improvement of mechanical and electrical properties is attributed to the obtained microstructure with increased homogenization and refinement,as well as improved interfacial bonding and reduced porosity.The strengthening mechanisms include dispersion and refinement strengthening for mechanical properties,as well as reduced electron scattering for electrical properties.

Hepatitis B core-related antigen as a promising serological marker for monitoring hepatitis B virus cure

Hepatitis B virus(HBV)infection is a global health concern.The current sequen-tial endpoints for the treatment of HBV infection include viral suppression,hepatitis B e antigen(HBeAg)seroconversion,functional cure,and covalently closed circular DNA(cccDNA)clearance.Serum hepatitis B core-related antigen(HBcrAg)is an emerging HBV marker comprising three components:HBeAg,hepatitis B core antigen,and p22cr.It responds well to the transcriptional activity of cccDNA in the patient's liver and is a promising alternative marker for serolo-gical testing.There is a strong correlation,and a decrease in its level corresponds to sustained viral suppression.In patients with chronic hepatitis B(CHB),serum HBcrAg levels are good predictors of HBeAg seroconversion(both spontaneous and after antiviral therapy),particularly in HBeAg-positive patients.Both low baseline HBcrAg levels and decreasing levels early in antiviral therapy favored HBsAg seroconversion,which may serve as a good surrogate option for treatment endpoints.In this review,we summarize the role of serum HBcrAg in the treat-ment of CHB.Therefore,long-term continuous monitoring of serum HBcrAg levels contributes to the clinical management of patients with CHB and optimizes the choice of treatment regimen,making it a promising marker for monitoring HBV cure.

生成式人工智能赋能本科生科研能力培养——ChatGPT支持的CUREs教学模式

为促进高等教育中高素质创新人才培养,构建以学生为中心的科研训练与课程教学整合模式是有效途径。当前基于课程的本科生科研体验(CUREs)教学模式虽在增强学生对科学本质的理解等方面具有一定优势,但在激发学生研究动机方面存在一些不足。将支持高效反馈的生成式人工智能ChatGPT引入人机协作研究过程中,有助于改善学生的科研体验,推动科研项目化学习。通过对ChatGPT支持的CUREs教学模式的设计与实施,发现该模式有助于培养学生的科研能力,提升他们的科研知识水平、科研技能水平和科研情感水平。尽管学生认同该教学模式的有效性和易用性,但其实际效果的发挥仍需人类智慧的参与。未来需要持续升级和优化生成式人工智能技术,确保技术应用高效且符合伦理标准;应用生成式人工智能技术重构教学模式,并通过长周期、跨场域实践检验其应用效果;强调人工智能与人类智慧的互补协作,真正实现生成式人工智能赋能学生科研能力提升。

Study on Loading Leaves Density with Cage Clamp on Quality of Cured Tobaccos in Bulk-Curing Barn

In order to determine the best loading density of tobacco leaf with cage clamp in bulk-curing barns, a curing test was conducted on middle-part tobacco leaves. The results showed that for good appearance quality of cured tobacco, the loading density at 59.52 kg/m2 （4 000 kg/barn） was the best, fol owed by 66.96 kg/m2 （4 500 kg/barn） and 74.40 kg/m2 （5 000 kg/barn）. As leaf loading density increased, the contents of leaf nicotine and total nitrogen increased, sugar content had smal changes, the ratio of sugar to nicotine decreased and tended to be balanced and the content of neutral aroma substances was decreasing, but the difference among treatments was not significant. With the increase of loading density, the sensory quality of cured leaf was better. When leaf loading density was 66.96 kg/m2 （4 500 kg/barn）, apperance quality of cured leaf improved considerably, with prominent aro-ma. Therefore, the best loading density of tobacco leaf in cage clamp of bulk-curing barn would be 66.96 kg/m2 （4 500 kg/barn） .

Curing Characteristics and Suitable Harvest Maturity of Fresh Flue-cured Tobacco Leaves in Ankang Tobacco Growing Areas

CuItivars K326, Yunyan 87 and Guiyan 4 were used to investigate the curing characteristics and suitabIe harvest maturity of fresh fIue-cured tobacco Ieaves in Ankang tobacco growing areas. ResuIts indicated that the water Ioss of K326 was sIow,and the Ieaves were resistant to curing and reIative easiIy to cure. The water Ioss of Yunyan 87 and Guiyan 4 were quick, and the Ieaves with normal resistance to curing were reIative difficuIt to cure. For Guiyan 4, the shrinkage of CM1 maturity was the Iargest. For K326 and Yunyan 87, the shrinkages of CM2 maturity were the Iargest whiIe the shrinkage of CM1 maturity was the Iowest, but the difference did not reach statistical significance. The proportion of top-middIe-grade tobacco Ieaves and average price for K326 were the highest with XM2, CM2 and BM2 maturity, and for Yunyan 87 were XM1, CM3 and BM2 maturity. For K326, Ieaves with XM2, CM2 and BM2 maturity showed the balanced chemical components and the best smoking quality.

Effects of Two Curing Methods on Quality of Yellow Sun-cured Tobacco

[Objective] The aim was to research effects of bamboo split curing method and steely barn curing method on quality of yellow sun-cured tobacco, providing scientific references for optimization of curing technology of yellow sun-cured tobacco. [method] The tobaccos were divided into two groups treated with two methods and the related indices of treated tobaccos were then measured to evaluate effects of curing methods on quality of yellow sun-cured tobacco. [Result] Tobaccos treated with two methods were all dominated by reddish yellow and yellow; exterior quality differed little. In detail, total sugar and reducing sugar in an average level in three locations were all higher with method A than those with method B, but nicotine and total N were lower; comprehensive chemical components in group with method B proved more appropriate with higher K. In addition, sensory qualities of leaves in moderate and bottom locations were better with method B compared with method A; sensory quality of top leaves was better; comprehensive sensory quality of leaves treated with method B proved better. On the other hand, cost for method A was 2.82 times of method B; the area of sun-curing field was 3.27 times and manage- ment work was 1.77 times, which indicated that method B is low-cost and time-saving, which would be a guarantee of tobacco quality. [Conclusion] The research provides scientific references for rational use of tobacco resources and optimization of sun-curing technology.

Effects of Different Flue-curing Barns on Aroma Quality of Upper Flue-cured Tobacco Leaves of K326

[Objective] This study was conducted to compare the aroma quality of up-per leaves of K326 flue-cured in different barns, and provide theoretical references for the development and optimization of bulk curing barn and the supporting tech-niques. [Method] The upper leaves of K326 were flue-cured in a commonness barn, a four-shelf bulk curing barn and a three-shelf bulk curing barn separately, and then the contents of aroma components and taste quality indices of the finished leaves were measured and compared. [Result] The contents of total aroma components, chromoplast pigment degradation products, phenylalanine aroma components and neophytadiene showed no significant differences in the leaves flue-cured in four-shelf bulk curing barn and commonness barn, but were significantly or very significantly higher than those in the leaves flue-cured in three-shelf bulk curing barn. The con-tents of carotenoid degradation products, Mail ard reaction products, cembranes aro-ma components and total aroma components （except neophytadiene） showed no significant difference among the three treatments. The results of sensory evaluation revealed that the sensory taste of the leaves flue-cured in four-shelf bulk curing barn was the best, as the finished leaves had rich, delicate aroma, comfortable and clean aftertaste. The leaves flue-cured in commonness barn was better than those flue-cured in three-shelf bulk curing barn in aroma quality, amount and aftertaste. [Conclusion] The four-shelf bulk curing barn had a large volume for tobacco leaf processing, but a similar baking environment to the commonness barn, which is conducive to the formation and accumulation of aroma components, so the finished leaves had similar appearance and quality with those flue-cured in commonness barn. The upper flue-cured leaves in three-shelf bulk curing bran had poorer quality than those flue-cured in the other two barns.

Cure Kinetics of DGEBA with Hyperbranched Poly(3-hydroxyphenyl) Phosphate as Curing Agent Studied by Non-isothermal DSC

The cure kinetics of diglycidyl ether of bisphenol A （DGEBA） with hyperbranched poly （3-hydroxyphenyl） phosphate（HHPP） as the curing agent was investigated by means of non-isothermal differential scanning calorimetry （DSC） at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene（DHB） as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible --P--O-- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Malek. It was found that the two-parameter autocatalytic model（Sestak-Berggren equation） is the most adequate one to describe the cure kinetics of the studied System at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.

Effects of Instantaneous High-pressure on Denaturalization of β-Lactoglobulin

[ Objective] The study aimed to explore the denaturalization law of β-Iactoglobulin （β-LG） under instantaneous high-pressure（IHP） con- dition. [Methed] Using fresh milk as testing material, effects of pressure, feed temperature and treatment time on the denaturalization of β-LG were studied via SDS-PAGE electrophoresis and sulfhydryl content detection after IHP treatment. [ Result] IHP could induce the agglomeration and depo- lymerization Of β-LG. The agglomeration of the β-LG increased with the elevated pressure from 20 to 60 MPa, but 80 MPa pressure led to depolyme- rization. The effect of feed temperature （25 -45 ℃） was similar to that of the pressure, while the influence of treatment time （2 -8 min） was not obvious. [ Conclusion] The study provided a theoretical basis for the elimination of allergens in β-LG and the application of IHP technology in milk treatment.

The Mechanism of Carotenoid Degradation in Flue-Cured Tobacco and Changes in the Related Enzyme Activities at the Leaf-Drying Stage During the Bulk Curing Process

The mechanism of carotenoid degradation and the changes in the activities of related enzymes in flue-cured tobacco at the leaf-drying stage during the bulk-curing process were studied in order to provide theoretical basis for optimization of curing technology. The effect of different rising speeds of temperature on the carotenoid degradation and the related enzymes activities at the color-fixing stage during the bulk curing process was studied by using the electric-heated fluecuring barn designed by Henan Agricultural University, China, based on curing technology with yellowing at low temperature and moderate humidity and leaf drying at moderate humidity. The results showed that the carotenoid degradation components （β-carotene, lutein, neoxanthin, and violaxthin） decreased gradually at the color-fixing stage during the bulk curing process. The carotenoid degradation components viz.,β-carotene, lutein, neoxanthin, and violaxthin at the slow heating curing （T1） were relatively higher than the rapid heating curing （T2） accounting for 10, 2, 32 and 32% respectively, but there were no differences among treatments （P〉 0.05）. The effect of different conditions of curing on the activities of enzymes related to carotenoids degradation were significant. The lipoxygenase, phenylalanine ammonialyase, peroxidase, and polyphenol oxidase enzymes had a bidirectional effect on the quality of tobacco leaves and it was beneficial to form more premise matter of aroma based on the higher enzyme activities at the early leaf-drying stage. The slow heating could regulate the change in various enzymes＇ activities reasonably, making cell redox reaction to reach the dynamic balance and make the degradation of carotenoids adequately. Meanwhile, it could avoid the occurrence of browning reaction and provide foundation for improving the quality of tobacco and optimization of technology for bulk curing and further enhancing aroma.

Effect of high-pressure homogenization on stability of emulsions containing zein and pectin

The aim of this study was to investigate the effect of high-pressure homogenization on the droplet size and physical stability of different formulations of pectin–zein stabilized rice bran oil emulsions. The obtained emulsions, both before and after passing through highpressure homogenizer, were subjected to stability test under environmental stress conditions,that is, temperature cycling at 4 °C/40 °C for 6 cycles and centrifugal test at 3000 rpm for 10 min. Applying high-pressure homogenization after mechanical homogenization caused only a small additional decrease in emulsion droplet size. The droplet size of emulsions was influenced by the type of pectin used;emulsions using high methoxy pectin(HMP) were smaller than that using low methoxy pectin(LMP). This is due to a greater emulsifying property of HMP than LMP. The emulsions stabilized by HMP–zein showed good physical stability with lower percent creaming index than those using LMP, both before and after passing through high-pressure homogenizer. The stability of emulsions after passing through high-pressure homogenizer was slightly higher when using higher zein concentration, resulting from stronger pectin–zein complexes that could rearrange and adsorb onto the emulsion droplets.

Tectonic Evolution of an Early Precambrian High-Pressure Granulite Belt in the North China Craton

A large-scale high-pressure granulite belt (HPGB), more than 700 km long, is recognized within the metamorphic basement of the North China craton. In the regional tectonic framework, the Hengshan-Chengde HPGB is located in the central collision belt between the western block and eastern block, and represents the deep crustal structural level. The typical high-pressure granulite (HPG) outcrops are distributed in the Hengshan and Chengde areas. HPGs commonly occur as mafic xenoliths within ductile shear zones, and underwent multipile deformations. To the south, the Hengshan-Chengde HPGB is juxtaposed with the Wutai greenstone belt by several strike-slip shear zones. Preliminary isotopic age dating indicates that HPGs from North China were mainly generated at the end of the Neoarchaean, assocaited with tectonic assembly of the western and eastern blocks.

A study of hydrate plug formation in a subsea natural gas pipeline using a novel high-pressure flow loop

The natural gas pipeline from Platform QKI8-1 in the southwest of Bohai Bay to the onshore processing facility is a subsea wet gas pipeline exposed to high pressure and low temperature for a long distance. Blockages in the pipeline occur occasionally. To maintain the natural gas flow in the pipeline, we proposed a method for analyzing blockages and ascribed them to the hydrate formation and agglomeration. A new high-pressure flow loop was developed to investigate hydrate plug formation and hydrate particle size, using a mixture of diesel oil, water, and natural gas as experimental fluids. The influences of pressure and initial flow rate were also studied. Experimental results indicated that when the flow rate was below 850 kg/h, gas hydrates would form and then plug the pipeline, even at a low water content （10%） of a water/oil emulsion. Furthermore, some practical suggestions were made for daily management of the subsea pipeline.

Protolith ages and timing of peak and retrograde metamorphism of the high-pressure granulites in the Shandong Peninsula,eastern North China Craton

High-pressure （HP） granulites widely occur as enclaves within tonalite-trondhjemite- granodiorite （TTG） gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North China Craton （NCC）. Based on cathodoluminescence （CL）, laser Raman spec- troscopy and in-situ U-Pb dating, we characterize the zircons from the HP granulites and group them into three main types： inherited （magmatic） zircon, HP metamorphic zircon and retrograde zircon. The inher- ited zircons with clear or weakly defined magmatic zoning contain inclusions of apatites, and 207pb/206pb ages of 2915--2890 Ma and 2763--2510 Ma, correlating with two magmatic events in the Archaean base- ment. The homogeneous HP metamorphic zircons contain index minerals of high-pressure metamor- phism including garnet, clinopyroxene, plagioclase, quartz, rutile and apatite, and yield 207pb/2066pb ages between 1900 and 1850 Ma, marking the timing of peak HP granulite facies metamorphism. The retrograde zircons contain inclusions of orthopyroxene, plagioclase, quartz, apatite and amphibole, and yield the youngest 207pb/206pb ages of 1840-1820 Ma among the three groups, which we correlate to the medium to low-pressure granulite facies retrograde metamorphism. The data presented in this study suggest subduction of Meso- and Neoarchean magmatic protoliths to lower crust depths where they were subjected to HP granulite facies metamorphism during Palaeoproterozoic （1900-1850 Ma）. Subse- quently, the HP granulites were exhumated to upper crust levels, and were ovel-printed by medium to low-pressure granulite and amphibolite facies retrograde event at ca. 1840--820 Ma.

Gas Film Disturbance Characteristics Analysis of High-Speed and High-Pressure Dry Gas Seal

The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal（S-DGS） with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what＇s more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.

Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs.However,the mechanisms and capacity are still unclear,which significantly limits the application of this technique.In order to figure out the mechanisms,the whole process of pressurizing,high-pressure soaking,and depressurizing was firstly discussed,and a mechanistic model was established.Subsequently,the simulation model was verified and employed to investigate the significances of high-pressure soaking,the contributions of different mechanisms,and the sensitivity analysis in different scenarios.The results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic fracturing.The contribution of imbibition increases as the increase in bottom hole pressure(BHP),interfacial tension,and specific surface area,but slightly decreases as the oil viscosity increases.In addition,it first decreases and then slightly increases with the increase in matrix permeability.The optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface area.Moreover,it shows a rising tendency as the interficial tension(IFT)increases.Overall,a general model was achieved to calculate the optimal soaking time.