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Study on tungsten sintering temperature field based on electromagnetic simulation and computational fluid dynamics

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Tungsten 2024年第2期6卷 355-366页

作者： Lu-Yan Wang Yue-Guang Yu Jian-Xin Dong Kai-Ping Du Shan-Yu Liu Cao-Bing Li University of Science and Technology Beijing Beijing 100083China BGRIMM Technology group Beijing 100160China China Iron&Steel Research Institute group Beijing 100081China

In order to study the influence of various sintering variables more intuitively and clearly,electromagnetic field analysis and computational fl uid dynamics are used to analyze the infl uence of gas flow,heating power and other process parameters on the temperature range of medium-frequency sintering in this paper.The results indicate that the uniformity of temperature fi eld is determined by the gas flow rate and heating power.When the heating power is 50 kW,the stable temperature drops about 10 K for every 1 m^(3)·h^(−1)increase of hydrogen flow.The peak value of the maximum temperature diff erence on the tungsten rods gradually increases with the increase of the hydrogen flow rate,and it appears slightly later.The temperature distribution of tungsten rods in furnace is similar with diff erent hydrogen flow rate.At the same time,the closer to the furnace wall,the higher the temperature of the tungsten rod.The temperature diff erence between tungsten rods mainly occurred within 1 h after the beginning of heating.Increasing the heating power can improve the stable temperature,but has little eff ect on the heating time.Increasing heating power can increase the peak value of the maximum temperature diff erence on the tungsten rods,but has little eff ect on the occurrence time of the peak value of the maximum temperature diff erence on the tungsten rods.Increasing the heating power will increase the temperature diff erence of a single tungsten rod,but the temperature diff erence of a single tungsten rod never exceeds 65 K.This study can be used to guide the process optimization design.Combined with numerical simulation calculation,the sintering parameters with low energy consumption and high temperature uniformity can be quickly and eff ectively found,thus improving the microstructure and properties of sintered tungsten products.

关键词： Tungsten products Sintering Hydrogen flow rate Heating power

Effect of TiB_(2)Addition on Microstructure and Mechanical Properties of AA8009 Alloy Fabricated by Laser Additive Manufacturing

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 67-77页

作者： Xinxing Xiong Sijie Yu Pei Wang Junfang Qi Haichao Li Xulei Wang Michael Ryan Debajyoti Bhaduri Rossitza Setchi Additive Manufacturing Institute Shenzhen UniversityShenzhen518060China Henan Key Laboratory of High Performance Carbon Fiber Reinforced Composites Institute of Carbon Matrix CompositesHenan Academy of SciencesZhengzhou450046China School of Materials Science and Engineering Shanghai University of Engineering ScienceShanghai201620China School of Materials Science and Engineering Zhengzhou University of AeronauticsZhengzhou450046China High-Value Manufacturing Research group School of EngineeringCardiff UniversityCardiffCF243AAUK

The research involves the addition of 5 vol.%TiB_(2)particles into AA8009 alloy powder to synthesize TiB_(2)/AA8009 composite parts produced via laser powder bed fusion(LPBF).The addition of the TiB_(2)particles causes the TiB_(2)/AA8009 composites with and without annealing have lower compressive strength than AA8009 alloy due to the change of the strengthening mechanism.The results further indicated that solid solution strengthening was the main strengthening mechanism of the LPBF AA8009 alloy at room temperature whereas Orowan strengthening became the primary strengthening factor after annealing at 673 K.In contrast,Orowan strengthening always remained the main strengthening mechanism for the TiB_(2)/AA8009 composite,irrespective of the annealing temperature.In addition,after annealing of the LPBF parts at 673 K,the compressive yield strength(CYS)of the unblended AA8009 alloy specimens had a~2.5 times greater reduction(from 705±16 to 459±30 MPa)compared to that of the composite TiB_(2)/AA8009 samples(from 466±23 to 368±3 MPa).Therefore,TiB_(2)particles can suppress the drop in yield strength of LPBF AA8009 alloy below 673 K,providing a theoretical and experimental basis for the applications of both LPBF AA8009 and TiB_(2)/AA8009 alloys at low and medium temperatures.

关键词： Laser powder bed fusion AA8009 alloy Microstructure Mechanical properties

Rapid growth in a large Cambrian apex predator

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National Science Review 2024年第3期11卷 128-136页

作者：吴雨 Stephen Pates Daniel Pauly 张兴亮傅东静 State Key Laboratory of Continental dynamics and Shaanxi Key Laboratory of Early Life and Environment Department of Geology Northwest University Department of Zoology University of Cambridge Institute for the Oceans and Fisheries University of British Columbia Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences

Despite the importance of ontogenetic data on early diverging euarthropods to our understanding of the ecology and evolution of past life, the data are distinctly lacking, as reconstructing life histories of fossil animals is often challenging. Here we report the growth trajectory of frontal appendages of the apex predator Amplectobelua symbrachiata, one of the most common radiodont arthropods from the early Cambrian Chengjiang biota(c. 520 Ma) of China. Analysis of 432 specimens(9.1–137.1 mm length; 1.3–25.6 mm height) reveals that appendages grew isometrically, with an estimated maximum size of the whole animal of c. 90 cm. Individuals grew rapidly compared to extant arthropods, as assessed using the electronic length-frequency analysis(ELEFAN) approach. Therefore, we show that the Cambrian apex predator A. symbrachiata was an extremely fast-growing arthropod, with an unusual life history strategy that formed as part of the escalatory ‘arms race’ that shaped the Cambrian explosion over 500 Ma.

关键词： stem-group Euarthropoda Radiodonta post-embryonic development growth dynamics Cambrian Explosion

Performance analysis of the tight combination of GPS, BDS, GALILEO,and QZSS mixed frequencies signals

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Geodesy and Geodynamics 2024年第4期15卷 366-378页

作者： Yu Han Fangjun Qin Xugang Lian Shengliang Wang Leiyuan Qian Wenhua Huang College of Electrical Engineering Naval University of Engineering College of Mining Engineering Taiyuan University of Technology State Key Laboratory of Satellite Navigation System and Equipment Technology State Key Laboratory of Geodesy and Earth's dynamics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences China Energy Engineering group Shanxi Electric Power Engineering CO.LTD.

With the gradual development and modernization of satellite navigation systems, using observation information from multi-GNSS has become one of the hot-spot issues in recent years. Multi-system loose combinations form double-difference observation equations within their respective systems, and the positioning effect is improved. However, the interchangeability and compatible interoperability between global navigation satellite systems(GNSS) cannot be truly realized. At the same time, when the number of visible satellites decreases abruptly, the positioning performance deteriorates sharply. This paper focuses on the GNSS multi-system tight combination relative positioning technique, gives a mathematical model of multi-system tight combination relative positioning considering differential intersystem bias(DISB), and analyzes the time-varying characteristics of DISB at overlapping and nonoverlapping frequencies among GPS/Galileo, GPS/BDS, and GPS/QZSS in terms of receiver brand, temperature, and receiver restart. The GNSS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology. The results show that compared with loose combination, the ambiguity-fixed rate increases from 62.18% to 97.60% for static data and from 74.97% to 99.53% for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.

关键词： GNSS Mix frequencies Redundancy Tight combination Differential inter-system bias

Impact of transparent exopolymer particles on the dynamics of dissolved organic carbon in the Amundsen Sea,Antarctica

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Advances in Polar Science 2024年第1期35卷 123-131页

作者： HU Ji XUE Siyou ZHAO Jun LI Dong ZHANG Haifeng YU Peisong ZHANG Cai YANG Xufeng PAN Jianming Key Laboratory of Marine Ecosystem dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China

The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.

关键词： dissolved organic matter chromophoric dissolved organic matter excitation-emission matrix coupled with parallel factor analysis transparent exopolymer particles Amundsen Sea Antarctica

A method for extracting the preseismic gravity anomalies over the Tibetan Plateau based on the maximum shear strain using GRACE data

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Earth and Planetary Physics 2024年第4期8卷 589-608页

作者： Hui Wang DongMei Song XinJian Shan Bin Wang College of Oceanography and Space Informatics China University of Petroleum(East China)Qingdao 266580China PCI Technology group Co. Ltd.Guangzhou 510660China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266200China State Key Laboratory of Earthquake dynamics Beijing 100029China

The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in gravity.The Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large earthquakes.However,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity changes.Moreover,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic activities.To explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal strain.The offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,respectively.In this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault zone.Second,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian Plate.Moreover,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.

关键词： Gravity Recovery And Climate Experiment(GRACE)data maximum shear strain offset index K preseismic gravity anomalies Tibetan Plateau fault zone

An improved installation of 2-hydroxy-4-methoxybenzyl(iHmb)method for chemical protein synthesis

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Chinese Chemical Letters 2024年第5期35卷 145-150页

作者： Ying Li Long-Jie Wang Yong-Kang Zhou Jun Liang Bin Xiao Ji-Shen Zheng The First Affiliated Hospital of USTC MOE Key Laboratory for Membraneless Organelles and Cellular DynamicsDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefei 230001China Department of Chemistry University of Science and Technology of ChinaHefei 230027China

The 2-hydroxy-4-methoxybenzyl(Hmb)backbone modification can prevent amide bond-mediated sidereactions(e.g.,aspartimide formation,peptide aggregation)by installing the removable Hmb group into a peptide bond,thus improving the synthesis of long and challenging peptides and proteins.However,its use is largely precluded by the limited Hmb’s installation sites.In this report,an improved installation of Hmb(iHmb)method was developed to achieve the flexible installation and the convenient removal of Hmb.The iHmb method involves two critical steps:(1)oxidative diazotization of the readily installed 2-hydroxy-4-methoxy-5-amino-benzyl(Hmab)to give 2-hydroxy-4-methoxy-5-diazonium-benzyl(Hmdab)by combining soamyl nitrite(IAN)/HBF_(4),and(2)reductive elimination of Hmdab to give the desired Hmb by 1,2-ethanedithiol(EDT).The iHmb method enables the installation of Hmb at any primary amino acid including the highly sterically hindered amino acids(e.g.,valine and isoleucine).The practicality and utility of the iHmb method was demonstrated by one-shot solid-phase synthesis of a challenging aspartimide-prone peptide,the mirror-image version of a hydrophobic peptide and a long-chain peptide up to 76-residue.Furthermore,the iHmb method can be utilized to facilitate chemical protein ligation,as exemplified by the synthesis of the single-spanning membrane protein sarcolipin.The iHmb method expands the toolkit for peptide synthesis and ligation and facilitates the preparation of peptides/proteins.

关键词： Chemical protein synthesis Solid-phase peptide synthesis Removable backbone modification 2-Hydroxy-4-methoxybenzyl(Hmb)group Aspartimide-prone peptides Difficult peptides Membrane proteins

Cancer cell cycle heterogeneity as a critical determinant of therapeutic resistance

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Genes & Diseases 2024年第1期11卷 189-204页

作者： Ebrahim H.Maleki Ahmad Reza Bahrami Maryam M.Matin Department of Biology Faculty of ScienceFerdowsi University of Mashhad*** MashhadIran Jagiellonian Centre for Experimental Therapeutics(JCET) Jagiellonian University31-007 KrakowPoland Doctoral School of Exact and Natural Sciences Jagiellonian University30-348 KrakowPoland Industrial Biotechnology Research group Institute of BiotechnologyFerdowsi University of Mashhad*** MashhadIran Novel Diagnostics and Therapeutics Research group Institute of BiotechnologyFerdowsi University of Mashhad***MashhadIran Stem Cell and Regenerative Medicine Research group Iranian Academic Center for EducationCulture and Research(ACECR)Khorasan Razavi Branch917751376 MashhadIran

Intra-tumor heterogeneity is now arguably one of the most-studied topics in tumor biology,as it represents a major obstacle to effective cancer treatment.Since tumor cells are highly diverse at genetic,epigenetic,and phenotypic levels,intra-tumor heterogeneity can be assumed as an important contributing factor to the nullification of chemotherapeutic effects,and recurrence of the tumor.Based on the role of heterogeneous subpopulations of cancer cells with varying cell-cycle dynamics and behavior during cancer progression and treatment;herein,we aim to establish a comprehensive definition for adaptation of neoplastic cells against therapy.We discuss two parallel and yet distinct subpopulations of tumor cells that play pivotal roles in reducing the effects of chemotherapy:"resistant"and"tolerant"popula-tions.Furthermore,this review also highlights the impact of the quiescent phase of the cell cycle as a survival mechanism for cancer cells.Beyond understanding the mechanisms under-lying the quiescence,it provides an insightful perspective on cancer stem cells(CsCs)and their dual and intertwined functions based on their cell cycle state in response to treatment.More-over,CSCs,epithelial-mesenchymal transformed cells,circulating tumor cells(CTCs),and disseminated tumor cells(DTCs),which are mostly in a quiescent state of the cell cycle are proved to have multiple biological links and can be implicated in our viewpoint of cell cycle heterogeneity in tumors.Overall,increasing our knowledge of cell cycle heterogeneity is a key to identifying new therapeutic solutions,and this emerging concept may provide us with new opportunities to prevent the dreadful cancer recurrence.

关键词： Cancer stem cells(CSCs) Carcinoma Cell cycle heterogeneity Quiescence Therapy resistance Therapy tolerance Tumor dormancy

Mussel-inspired PTW@PDA composites for developing high-energy gun propellants with reduced erosion and enhanced mechanical strength

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Defence Technology（防务技术） 2024年第2期32卷 675-690页

作者： Xijin Wang Zhitao Liu Pengfei Sun Feiyun Chen Bin Xu Xin Liao School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina China North Industries group Corporation Limited Beijing 100045China

The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.

关键词： High energy gun propellant Potassium titanate whiskers Polydopamine modification Erosion inhibitors Mechanical reinforcing fillers