Microstructure and mechanical properties stability of pre-hardening treatment in Al-Cu alloys for pre-hardening forming process

The stability of the microstructure and mechanical properties of the pre-hardened sheets during the pre-hardening forming(PHF)process directly determines the quality of the formed components.The microstructure stability of the pre-hardened sheets was in-vestigated by differential scanning calorimetry(DSC),transmission electron microscopy(TEM),and small angle X-ray scattering(SAXS),while the mechanical properties and formability were analyzed through uniaxial tensile tests and formability tests.The results in-dicate that the mechanical properties of the pre-hardened alloys exhibited negligible changes after experiencing 1-month natural aging(NA).The deviations of ultimate tensile strength(UTS),yield strength(YS),and sheet formability(Erichsen value)are all less than 2%.Also,after different NA time(from 48 h to 1 month)is applied to alloys before pre-hardening treatment,the pre-hardened alloys possess stable microstructure and mechanical properties as well.Interestingly,with the extension of NA time before pre-hardening treatment from 48 h to 1 month,the contribution of NA to the pre-hardening treatment is limited.Only a yield strength increment of 20 MPa is achieved,with no loss in elongation.The limited enhancement is mainly attributed to the fact that only a limited number of clusters are transformed into Guinier-Preston(GP)zones at the early stage of pre-hardening treatment,and the formation ofθ''phase inhibits the nucleation and growth of GP zones as the precipitated phase evolves.

进化信号博弈中的同义词优势（英文）

同义词是自然语言中普遍存在的语言现象,但同义的词或短语似乎并不在语言交流的有效性上占有优势。因而,自然语言中的同义词是一个需要被辩护和解释的性质。基于Lewis的信号博弈模型,Alexander等构建的带有新信号发明机制的博弈模型部分证明了同义词的优势,但该优势只是他们说明新信号发明机制的一个副产品。同义词在信号博弈中被证明能够有效地减少不成功的信息交流,从而提高交流的效率。作为Alexander等的工作的补充,在这篇文章中,我们论证了一定程度的同义性已经足够增强一个信号博弈的有效性。同时,我们还论证了新信号发明机制并不在激发同义词优势上具有决定性的作用。一个仅带有同义词的信号博弈模型可以达到与带有新信号发明机制的博弈模型达到同样的优势效果甚至有时候更好。

A DUAL-MODALITY OPTICAL BIOPSY APPROACH FOR IN VIVO DETECTION OF PROSTATE CANCER IN RAT MODEL

Ultrasound-guided biopsy procedure for prostate cancer diagnosis,which is the current gold standard,involves quasi-random sampling of prostate tissue without any functional guidance.In this study,we discuss the possibility to augment the detection of prostate cancer using a dual-modality optical approach,which can be coupled with the current needle biopsy setup.Two techniques are light reflectance spectroscopy(LRS)that uses a broadband light source and a CCD array spectrometer,and auto-fluorescence lifetime measurement(AFLM)that uses a custom-designed,time-correlated single photon counting(TCSPC)system.Both LRS and AFLM were employed sequentially in this study to measure cancer tissue along with control tissue on a rat prostate tumor model.At an excitation wavelength of 447 nm,we investigated auto-fluorescence decay curves at the emission wavelengths of 532,562,632 and 684 nm for in vivo and ex vivo AFLM.These results show that auto-fluorescence lifetimes at all measured emission wavelengths differ between control and cancerous tissues with 100% specificity and sensitivity.Moreover,absolute values of hemoglobin derivatives and scattering coe±cient were quantified using in vivo LRS.This part of study also demonstrates that light scattering and absorption are significantly different between the control and cancerous tissue.Overall,the study demonstrates that both LRS and AFLM may provide several intrinsic biomarkers for in vivo detection of prostate cancer.

从信号博弈初探社会因素与语言结构的关联

在哲学、社会语言学和认知语言学中,社会因素与语言结构的关联一直是被关注的问题。许多语言之外的因素被证明在语言结构及其性质中扮演了重要的角色。例如:社会环境和社会生态因素等。但是大部分在这一领域的结果都还是通过田野调查和实验方法获得的。本文将通过构建数学模型特别是博弈论模型来探究有哪些社会因素影响及如何影响语言结构的性质。本文集中讨论的社会因素包括:社会经验知识、语言使用成本以及社会人员组成。通过对刘易斯信号博弈模型的静态和动态的扩展,讨论以上社会因素如何与交流者的语言复杂度偏好相关联。

c-Met靶向分子影像探针的研究进展

间充质上皮细胞转化因子c-Met是蛋白酪氨酸激酶受体超家族成员之一,可通过其体内唯一配体肝细胞生长因子HGF介导的HGF/c-Met信号通路参与体内许多生理过程。研究表明c-Met的过表达或异常表达与多种实体瘤的发生发展密切相关,因此,针对c-Met这个靶点开发肿瘤早期诊断与靶向治疗的药物具有重大意义。该综述简述了c-Met/HGF信号通路及其分子靶向探针在肿瘤诊断中的应用进展,可为后期c-Met造影剂的探索开发和实际应用提供思路。

Controlling Osteogenic Differentiation through Nanoporous Alumina

Nanotopographical features are found to have significant effects on bone behavior. In the present study, nanoporous aluminas with different pore sizes (20, 100 and 200 nm in diameter), were evaluated for their osteoinductive and drug eluting properties. W20-17 marrow stromal cells were seeded on nanoporous alumina with and without the addition of BMP-2. Although cell proliferation was not affected by pore size, osteogenic differentiation was 200 nm as compared to 20 and 100 nm pores induced higher alkaline phosphatase activity (ALP) and osteocalcin expression levels, thus indicating osteoblastic differentiation. Cell morphology revealed that cells cultured on 20 nm pores adopted a rounded shape, while larger pores (200 nm) elicited an elongated morphology. Furthermore, ALP expression levels were consistently higher on BMP-2 loaded nanoporous alumina surfaces compared to unloaded surfaces, indicating that not only is nanoporous alumina osteoinductive, but also has the potential to be used as a drug eluting bone-implant coating.

Alleviating limit cycling in training GANs with an optimization technique

In this paper,we undertake further investigation to alleviate the issue of limit cycling behavior in training generative adversarial networks(GANs)through the proposed predictive centripetal acceleration algorithm(PCAA).Specifically,we first derive the upper and lower complexity bounds of PCAA for a general bilinear game,with the last-iterate convergence rate notably improving upon previous results.Then,we combine PCAA with the adaptive moment estimation algorithm(Adam)to propose PCAA-Adam,for practical training of GANs to enhance their generalization capability.Finally,we validate the effectiveness of the proposed algorithm through experiments conducted on bilinear games,multivariate Gaussian distributions,and the CelebA dataset,respectively.

Parameter sensitivity analysis of the axial stability for a marine flexible pipe

Marine unbonded flexible pipes serve as the most essential equipment in offshore oil and gas exploration and exploitation.Axial compressive loads during installation or in service in the complex marine environment usually lead to buckling failure.A flexible pipe is a composite structure with multiple functional layers,of which the tensile armor layer plays a key role with regard to the response of the pipe subjected to axial loads.In this paper,a simplified three-dimensional finite element model is developed,focusing on the tensile layer and replacing the carcass layer,pressure sheath layer,and pressure armor layer by a cylindrical rigid body to reduce computational expense.By using this model,the buckling failure modes of the tensile armor layer(in particular the birdcaging phenomenon)are analyzed.Several key parameters that affect the stability of the flexible pipe under axial compression and torsion are emphasized,and their effects on its axial and torsional stiffness are compared and discussed.The results show that both the lay angle of the steel wires and the interlayer friction coefficient have a significant influence on the axial and torsional stiffness of the pipe,whereas the damaged length of the outer sheath has virtually no effect.

Effects of irrigation level and method on soil salt balance and crop water use efficiency in arid oasis regions

Fresh water resource scarcity and soil salt accumulation in the root-zone are two key limiting factors for sustainable agricultural development in the oasis region of arid inland basin, northwest China. The aim of this study was to explore an appropriate irrigation scheme to maintain sustainable crop cultivation in this region. The effects of four irrigation levels (full irrigation, mild deficit, moderate deficit, and severe deficit) and three irrigation methods (border, surface drip and subsurface drip) on soil water and salt dynamics, highland barley (Hordeum vulgare L.) yield, and crop water use efficiency were studied by field plot experiments. The results showed that soil salt in 0-100 cm profile was accumulated under all experimental treatments after one season of highland barley planting, but the accumulated salt mass decreased with the decrease of the lower limit of irrigation. Salt mass in 0-100 cm soil profile under subsurface drip irrigation was 16.8%-57.8% and 2.9%-58.4% less than that under border and surface drip irrigation, respectively. The grain yield of highland barley decreased first and then increased with the decrease of the lower limit of irrigation under surface drip and subsurface drip irrigation, but it was on the contrary under border irrigation. Mean grain yield for all irrigation levels under subsurface drip irrigation was 5.7% and 18.8% higher than that under border and surface drip irrigation, respectively. Water use efficiency increased with the decrease of the lower limit of irrigation, and the averaged water use efficiency of all irrigation levels under subsurface drip irrigation was 11.9% and 14.2% higher than that under border and surface drip irrigation, respectively. Considering economic benefit and irrigation water requirement, subsurface drip irrigation with the lower limit of irrigation of 50%-55% field capacity is suggested for highland barley planting in the arid oasis region.

Gut microbial community structure and function of Przewalski’s horses varied across reintroduced sites in China

Host-associated microbiota can significantly impact host fitness.Therefore,naturally occurring variations in microbiota may influence the health and persistence of their hosts.This finding is particularly important in reintroduced animals,as they typically experience habitat changes during translocations.However,little is known about how microbiomes are altered in response to conservation translocation.Here,we accessed the gut microbiome of Przewalski’s horse(Equus przewalskii)populations in China from three nature reserves(i.e.Xinjiang Kalamaili Nature Reserve,KNR;Dunhuang Xihu National Nature Reserve,DXNNR;and Anxi Extreme-arid Desert Nature Reserve,AENR)using 16s rRNA gene and metagenome sequencing.The results showed that the microbial composition and function differed significantly across locations,while a subset of core taxa was consistently present in most of the samples.The abundance of genes encoding microbe-produced enzymes involved in the metabolism of carbohydrates,especially for glycoside hydrolases,was significantly higher in open-spaced KNR populations than in more confined AENR individuals.This study offers detailed and significant differential characters related to the microbial community and metabolic pathways in various reintroduced sites of Przewalski’s horse,which might provide a basis for future microecological and conservation research on endangered reintroduced animals.

多目标优化问题的Pascoletti-Serafini标量化方法

非线性标量化方法是研究非凸多目标优化问题的一个重要途径.目前Pascoletti-Serafini标量化方法是处理非凸多目标优化问题的有力工具之一.但绝大部分结果是针对多目标优化问题的弱有效解和有效解建立的.因此,本文深入研究Akbari等(2018)提出的3类改进的Pascoletti-Serafini标量化方法,主要考虑在什么条件下可以建立非凸多目标优化问题真有效解的非线性标量化刻画.通过限制相应标量化问题中的参数范围,获得了非凸多目标优化问题弱有效解、有效解和真有效解的充分和必要条件.此外,举例说明了主要结果.

Biofunctionalization of metallic implants by calcium phosphate coatings

Metallic materials have been extensively applied in clinical practice due to their unique mechanical properties and durability.Recent years have witnessed broad interests and advances on surface functionalization of metallic implants for high-performance biofunctions.Calcium phosphates(CaPs)are the major inorganic component of bone tissues,and thus owning inherent biocompatibility and osseointegration properties.As such,they have been widely used in clinical orthopedics and dentistry.The new emergence of surface functionalization on metallic implants with CaP coatings shows promise for a combination of mechanical properties from metals and various biofunctions from CaPs.This review provides a brief summary of state-of-art of surface biofunctionalization on implantable metals by CaP coatings.We first glance over different types of CaPs with their coating methods and in vitro and in vivo performances,and then give insight into the representative biofunctions,i.e.osteointegration,corrosion resistance and biodegradation control,and antibacterial property,provided by CaP coatings for metallic implant materials.

Promotion of Mn Doped Co/CNTs Catalysts for CO Hydrogenation to Light Olefins

With various contents, Mn was introduced into carbon nanotubes （CNTs） supported cobalt catalysts and the obtained Mn-Co/CNTs catalysts were investigated for CO hydrogenation to light alkenes and characterized by N2 ad- sorption, X-ray diffraction （XRD）, X-ray photoelectron spectra （XPS）, H2 temperature programmed reduction （TPR）, CO temperature programmed desorption （TPD） and transmission electron microscope （TEM）. The results indicate that the addition of a small amount of Mn （0.3 wt%） to CNTs-supported Co catalyst significantly increased the selectivity of C2--C4 olefins and decreased the selectivity of CH4. However, with further addition of Mn to the cobalt catalysts, the CH4 selectivity decreased obviously along with the increase of the C5 selectivity. Compared with the unpromoted catalysts, the Mn-promoted cobalt catalysts increased the C2=-C4=/C20- C40 molar ratio.

Recruitment of endogenous progenitor cells by erythropoietin loaded particles for in situ cartilage regeneration

Cartilage injury affects millions of people throughout the world,and at this time there is no cure.While transplantation of stem cells has shown some success in the treatment of injured cartilage,such treatment is limited by limited cell sources and safety concerns.To overcome these drawbacks,a microscaffolds system was developed capable of targeting,reducing the inflammatory response and recruiting endogenous progenitor cells to cartilage-defect.Erythropoietin(EPO)-loaded-hyaluronic acid(HA)microscaffolds(HA+EPO)were fabricated and characterized.HA-microscaffolds showed good cell-compatibility and could target chondrocytes via CD44 receptors.HA+EPO was designed to slowly release EPO while recruiting progenitor cells.Finally,the ability of HA+EPO to repair cartilage-defects was assessed using a rabbit model of full-thickness cartilagedefect.Our results showed that the intra-articular administration of EPO,HA,and EPO+HA reduced the number of inflammatory cells inside the synovial-fluid,while EPO+HA had the greatest anti-inflammatory effects.Furthermore,among all groups,EPO+HA achieved the greatest progenitor cell recruitment and subsequent chondrogenesis.The results of this work support that,by targeting and localizing the release of growthfactors,HA+EPO can reduce inflammatory responses and promote progenitor cells responses.This new platform represents an alternative treatment to stem-cell transplantation for the treatment of cartilage injury.

Metagenomics reveals contrasting energy utilization efficiencies of captive and wild camels(Camelus ferus)

Captive conditions can affect the symbiotic microbiome of animals.In this study,we compared the structural and functional differences of the gastrointestinal microbiomes of wild Bactrian camels(Camelus ferus)between wild and captive populations,as well as their different host energy utilization performances through metagenomics.The results showed that wild-living camels harbored more microbial taxa related to the production of volatile fatty acids,fewer methanogens,and fewer genes encoding enzymes involved in methanogenesis,leading to higher energy utilization efficiency compared to that of captive-living camels.These findings suggest that the wild-living camel fecal microbiome demonstrates a series of adaptive characteristics that enable the host to adjust to a relatively barren field environment.Our study provides novel insights into the mechanisms of wildlife adaptations to habitats from the perspective of the microbiome.

Study of K/Mn-MgO Supported Fe Catalysts with Fe（CO）5 and Fe（NO3）3 as Precursors for CO Hydrogenation to Light Alkenes

Two K/Mn-MgO supported catalysts were prepared by Fe（CO）5 and Fe（NO3）3 as precursor respectively. The obtained Fe-K/Mn-MgO catalysts were tested for CO hydrogenation to light alkenes and characterized by X-ray powder diffraction （XRD）, X-ray photoelectron spectra （XPS）, H2 temperature-programmed reduction （H2-TPR）, H2 CO and CO2 temperature-programmed desorption （H2, CO/CO2-TPD） and transmission electron microscope （TEM） The results indicated that the catalyst with 10 wt% Fe loading prepared by Fe（CO）5 as precursor showed better performance in syngas to light alkenes than ones obtained from Fe（NO3）3 as precursor, where the CO conversion was 62.50% and the selectivity was 55.95% at 350 ℃, 1.5 MPa and 1000 h^-1, respectively.

Study of the influences of rotary table speed on stick-slip vibration of the drilling system

Stick-slip vibration presents one of the major causes of drilling problems,such as premature tool failures,low drilling efficiency and poor wellbore quality.The objective of this work is to investigate the influences of rotary table speed(RTS)on stick-slip phenomenon of the drilling system.In this study,the drilling system is treated as a lumped torsional pendulum model of which the bit/rock interaction is regarded as Coulomb friction.By analyzing cases with different RTS,two types of vibrations on the bit are found:stick-slip vibration and uniform motion.With an increase in the RTS,the stick-slip vibration on the drill bit disappears once the RTS arrives at its critical value.For the cases that stick-slip vibrations occur,the phase trajectories converge toward a limit cycle.For the cases that stick-slip vibration does not appear,the drill bit tends to stabilize at a uniform motion and the phase trajectories correspond to contracting spirals observed in the phase plane.

A pretargeting nanoplatform for imaging and enhancing anti-inflammatory drug delivery

This work details a newly developed“sandwich”nanoplatform via neutravidin-biotin system for the detection and treatment of inflammation.First,biotinylated-and folate-conjugated optical imaging micelles targeted activated macrophages via folate/folate receptor interactions.Second,multivalent neutravidin proteins in an optimal concentration accumulated on the biotinylated macrophages.Finally,biotinylated anti-inflammatory drug-loaded micelles delivered drugs effectively at the inflammatory sites via a highly specific neutravidin-biotin affinity.Both in vitro and in vivo studies have shown that the“sandwich”pretargeting platform was able to diagnose inflammation by targeting activated macrophages as well as improve the therapeutic efficacy by amplifying the drug delivery to the inflamed tissue.The overall results support that our new pretargeting platform has the potential for inflammatory disease diagnosis and treatment.

Click chemistry-based pre-targeting cell delivery for cartilage regeneration

A fraction of the OA patient population is affected by post-traumatic osteoarthritis(PTOA)following acute joint injuries.Stopping or reversing the progression of PTOA following joint injury could improve long-term functional outcomes,reduced disability,and medical costs.To more effectively treat articular cartilage injury,we have developed a novel cell-based therapy that involves the pretargeting of apoptotic chondrocytes and the delivery of healthy,metabolically active chondrocytes using click chemistry.Specifically,a pre-targeting agent was prepared via conjugating apoptotic binding peptide(ApoPep-1)and trans-cyclooctene(TCO)onto polyethylene glycol(PEG)polymer carrier.The pre-targeting agent would be introduced to injured areas of articular cartilage,leading to the accumulation of TCO groups on the injured areas from actively binding to apoptotic chondrocytes.Subsequently,methyltetrazine(Tz)-bearing chondrocytes would be immobilized on the surface of TCO-coated injured cartilage via Tz-TCO click chemistry reaction.Using an ex vivo human cartilage explant PTOA model,the effectiveness of this new approach was evaluated.Our studies show that this novel approach(Tz-TCO click chemistry)significantly enhanced the immobilization of healthy and metabolically active chondrocytes to the areas of apoptotic chondrocytes.Histological analyses demonstrated that this treatment regimen would significantly reduce the area of cartilage degeneration and enhance ECM regeneration.The results support that Tz-TCO click chemistry-mediated cell delivery approach has great potential in clinical applications for targeting and treatment of cartilage injury.

On the formation of limit cycle of the friction-induced stick-slip vibration in oilwell drillstring

In this paper,the stick-slip vibration in oilwell drillstring is studied.The drilling system is modelled as a lumped-parameter torsional pendulum and the interaction between the drill bit and the rock is treated as Coulomb friction.Equation of motion of the drill bit is established and the dynamic responses of the drill bit are obtained.A drilling system with the drillstring length 3000 m is analysed,in which the system parameters are selected by reference to the actual drilling situation.After the slip vibrations in the initial stage,final state of the drill bit is a stable stick-slip vibration of which the limit cycle is a closed loop.In order to find the stability of the limit cycle corresponds to the periodically stick-slip vibration,different initial conditions for the drill bit are studied.Results show that the drill bit will lead to a periodic motion and the phase trajectories ultimately converge to the same limit cycle corresponds to stable stick-slip vibration.