Effect of neutral polymeric bonding agent on tensile mechanical properties and damage evolution of NEPE propellant

Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.

Multifunctional Integrated Organic-Inorganic-Metal Hybrid Aerogel for Excellent Thermal Insulation and Electromagnetic Shielding Performance

Vehicles operating in space need to withstand extreme thermal and electromagnetic environments in light of the burgeoning of space science and technology.It is imperatively desired to high insulation materials with lightweight and extensive mechanical properties.Herein,a boron-silica-tantalum ternary hybrid phenolic aerogel(BSiTa-PA)with exceptional thermal stability,extensive mechanical strength,low thermal conductivity(49.6 mW m^(-1)K^(-1)),and heightened ablative resistance is prepared by an expeditious method.After extremely thermal erosion,the obtained carbon aerogel demonstrates noteworthy electromagnetic interference(EMI)shielding performance with an efficiency of 31.6 dB,accompanied by notable loading property with specific modulus of 272.8 kN·m kg^(-1).This novel design concept has laid the foundation for the development of insulation materials in more complex extreme environments.

Investigation of high rate mechanical flow followed by ignition for high-energy propellant under dynamic extrusion loading

Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident stimulus.Secondly, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.

LA-D-B1,a novel Abemaciclib derivative,exerts anti-breast cancer effects through CDK4/6

Background:Regulatory proteins involved in human cellular division and proliferation,cyclin-dependent kinases 4 and 6(CDK4/6)are overexpressed in numerous cancers,including triple-negative breast cancer(TNBC).TNBC is a common pathological subtype of breast cancer that is prone to recurrence and metastasis,and has a single treatment method.As one of the CDK4/6 inhibitors,abemaciclib can effectively inhibit the growth of breast tumors.In this study,we synthesized LA-D-B1,a derivative of Abemaciclib,and investigated its anti-tumor effects in breast cancer.Methods:Cellular viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay.Cell cloning and migration abilities were determined by colony formation assay and wound healing assay.Cell invasion abilities and adhesion were determined by cell invasion assay and cell adhesion assay.The impact of compound LA-D-B1 on cell proliferation and the cell cycle was analyzed through Western blotting,which quantified the levels of proteins associated with the cyclin-dependent kinase(CDK)4/6-cyclin D-Rb-E2F pathway.The in vivo anti-tumor activity of compound LA-D-B1 was investigated using a chick chorioallantoic membrane(CAM)model.Results:The study demonstrated that LA-D-B1 effectively suppressed breast cancer cell proliferation,induced apoptosis,and caused cell cycle arrest.Furthermore,LA-D-B1 reduced the expression of key proteins in the CDK4/6-cyclin D-Rb-E2F pathway,including CDK4,CDK6 and E2F1.The results also indicated significant antitumor activity of LA-D-B1 in a transplanted tumor model.Conclusion:In this study,LA-D-B1 demonstrated a potent anti-tumor effect by effectively suppressing cell proliferation and inhibiting cell cycle progression in breast cancer.These findings highlight the potential of LA-D-B1 as a valuable compound for enhancing therapeutic outcomes and controlling the progression of breast cancer.

热熔型BA221氰酸酯树脂的固化动力学及流变行为

氰酸酯(CE)树脂具有高度对称的化学结构和强结晶性,固化反应温度高,固化物脆性大,容易从预浸料中结晶析出并悬浮于表面,严重影响了预浸料的表观质量、制备工艺和力学性能。文中采用F-51酚醛环氧改性CE树脂,通过预聚工艺制备了一种室温下为半固态、成膜性好、适用期长、适用于热熔法预浸料工艺的热熔型CE树脂(代号BA221)。采用差示扫描量热法研究了BA221树脂的固化动力学和固化反应参数,获得了固化动力学方程,优化了固化制度,活化能较CE树脂降低了66.9%。采用流变法研究了BA221树脂的黏度变化规律,确定了热熔型BA221树脂的制膜温度为80℃,获得了成膜性和延展性良好的热熔胶膜。BA221树脂固化物的玻璃化转变温度为268.4℃,拉伸强度和延伸率分别为79.7 MPa和3%,弯曲强度和冲击强度分别为122 MPa和21 k J/m2,较CE树脂分别提高了96.3%,134.4%,76%和270%。扫描电镜结果表明BA221树脂固化物为韧性断裂。F-51酚醛环氧改性CE树脂效果显著,实现了CE树脂在120℃预聚、80℃成膜和180℃后固化的工程化应用目标,为制备热熔法预浸料提供了一种耐高温CE树脂。

液态聚碳硅烷的结构及固化行为对其陶瓷化的影响

液态聚碳硅烷作为一种新型陶瓷先驱体,可通过先驱体浸渍裂解工艺(PIP)制备陶瓷基复合材料(CMC),也可通过包覆有机纤维来提高柔性绝热层的耐烧蚀性能。文中通过红外光谱和核磁共振表征了3种液态聚碳硅烷先驱体VHPCS,VHPCS-S和AHPCS的结构组成,在150℃前的固化反应主要通过C═C键以多种方式进行,与AHPCS相比,VHPCS和VHPCS-S中双键与硅氢键的摩尔比提高了约18.2%;采用非等温差示扫描量热分析(DSC)法研究了3种先驱体及其在交联剂过氧化二异丙苯体系时的固化反应动力学,发现固化反应温度和表观活化能均有所降低,先驱体可以在低温下实现快速交联反应;利用同步热分析和X射线衍射分析了先驱体的陶瓷化过程及裂解产物的结晶行为,VHPCS-S在1200℃时的陶瓷产率高于其余2种先驱体VHPCS与AHPCS。对于DCP/VHPCS-S交联体系,在150℃固化后陶瓷产率达到89.82%。此外,DCP的加入可以有效抑制β-SiC结晶。

Inherent relationship between process parameters,crystallization and mechanical properties of continuous carbon fiber reinforced PEEK composites

High-performance thermoplastic composites have been developed as significant structural materials for cutting-edge equipment in the aerospace and defence fields.However,the internal mechanism of processing parameters on mechanical properties in the manufacturing process of thermoplastic composite structures is still a serious challenge.The purpose of this study is to investigate the process/crystallization/property relationships for continuous carbon fiber(CF)reinforced polyether-ether-ketone(PEEK)composites.The composite laminates are fabricated according to orthogonal experiments via the thermoforming method.The mechanical performance is investigated in terms of crystallization properties and fracture morphology characterizations.Experimental results show that the mechanical performance and crystallization properties of thermoplastic composites are significantly affected by the coupling of processing parameters.The increased molding temperature,pressure,and holding time improve the degree of fiber/matrix infiltration and affect the crystallinity and crystalline morphology of the matrix,which further influences the mechanical properties of the composites.This is reflected in the test results that crystallinity has an approximately linear effect on mode-I interlaminar fracture toughness and transverse flexural modulus.As well as the higher molding temperature can destroy the pre-existent crystals to improve the toughness of the matrix,and the well-defined crystalline structures can be observed when fabricated at higher temperatures and longer periods of holding time.

Damage-ignition mechanism studies on modified propellant with different crosslinking density under dynamic loading

The study of high-energy and low-vulnerability propellants is important for the power performance and safety of solid propellant rocket motors.The modified split Hopkinson pressure bar(SHPB)tests are performed on two kinds of propellant with different crosslinking density to study the dynamic mechanical responses and damage-ignition mechanism.SHPB apparatus is equipped with a highperformance infrared camera and high-speed camera to capture the deformation,damage-ignition feature and temperature evolution images in the impact process.The results suggested that the mechanical responses and damage-ignition mechanism of the propellants were affected by the strain rates and crosslinking density.The damage-ignition degree is more intense and the reaction occurs earlier with the increase of strain rates.For propellant 1 with higher crosslinking density,the critical ignition strain rate is 4500 s^(-1).Two kinds of propellants show different ignition mechanism,i.e.crack generation,propagation and final fracture for propellant 1 while viscous shear flow for propellant 2.Meanwhile,the SEM images also reveal the difference of damage-ignition mechanism of the two kinds of propellants.Finally,the ignition mechanism under different strain rates and critical ignition strain rate of propellants are further explained by the theoretical calculation of temperature variations.

Study of family environmental factor on only-children’s personality

Objective: To analyze the impact of family environment on only-children’s personality. Methods: Using cross-sectional design to recruit only-children aged 6 - 16 years old;using EPQ to evaluate the children’s personality. The general questionnaire, PSDQ (Parenting Styles and Dimensions Questionnaire), FAD-GFS (The General Functioning Scale of MacMaster family activity device), SLE(Stressful Life Events), FSQ (Family Stresses Questionnaire), FLQ (Family Life Questionnaire), EFQ (Everyday Feelings Questionnaire) were used to collect information about family environment from parents. Results: In only-child family, standardized regression equations of family environment influence on children personality include: 1) EPQ-p = 0.087 × SLE + 0.207 × father autocratic parenting + 0.131 × education of father + 0.110 × family type - 0.110 × role of discipline - 0.080 × parental attitude + 0.087 × family adaptability;2) EPQ-e = 0.105 × EFQ- 0.088 × SLE - 0.101 × family income;3) EPQ-n = 0.143 × SLE - 0.090 × family cohesion + 0.089 × family income + 0.117 × the orderly’s attitude - 0.138 × the child’s role experience of FLQ - 0.101 × parents shaping the behavior of children of FLQ and 4) EPQ - l = -0.136× SLE - 0.093 × relationship between parents - 0.155 × attitude of the old. Conclusion: It is important for children to develop personality normally if the father doesn’t choose autocratic parent style. Children tend to be optimistic if the parent can feel happy. The stressful life events are a double-blade sword depending on the parent’s handling. The difference of the parenting style can influence the lie-personality of children.

A temperature/strain-rate-dependent finite deformation constitutive and failure model for solid propellants

The stress-strain response under progressive damage and the ultimate failure of solid propellants are two key issues affecting the integrity of solid rocket motors.Previous research primarily focused on the progressive damage in solid propellants during production and storage.However,they failed to take the temperature/strain-rate-dependent ultimate failures into consideration.The failure strains of solid propellants are experimentally observed to show strong temperature/strain-rate dependence and exhibit an abnormal evolution at low and high temperatures,respectively.With increasing loading strain rate,the failure strains decrease at low temperatures near the glass transition temperature(T_g)but increase at high temperatures far above T_(g).In this study,we introduce the glassy and rubbery failure criteria based on strain energy densities at ultralow and ultrahigh temperatures,respectively,into a viscoelastic constitutive model and build a unified model for the progressive damage and the ultimate failure of solid propellants.With the introduction of these two additional criterion parameters,the developed model can effectively predict the yield-type stress-strain responses,microscopic damage-induced volume dilatations,and temperature/strain-ratedependent ultimate failures of the solid propellants by comparing the model predictions with the experimental results.The competition between the glassy failure and the rubbery failure results in the propellants exhibiting a maximum break strain near the glass transition temperature.Consequently,when the strain rate is increased,the propellants exhibit a predominantly glassy response,which shifts the failure envelope toward a higher temperature.This induces an abnormal evolution of failure strains by making the propellants stretchable at high temperatures and brittle at low temperatures.

Two birds with one stone:Construction of bifunctional-POSS hybridized boron-silicon ceramicized phenolic composites and its ablation behavior

To further enhance the ablation resistance properties of thermosetting phenolic resin matrix composites,in this work,bifunctional alkalic heptaphenyltrisilanol sodium salt polyhedral oligomeric silsesquioxane was utilized to catalyze the synthesis of boron phenolic resin and provide silicon source to obtain boron-silicon hybrid phenolic resin(BPOSSPR)with excellent ablative resistance.BPOSSPR possesses a low cur-ing activation energy(101.4 kJ/mol)and excellent thermal properties(initial decomposition temperature was 453.0℃and char yield at 1000℃was 72.7%).The mechanical and thermal insulation properties of carbon fiber reinforced BPOSSPR composites(CF/BPOSSPR)and high silica fiber reinforced BPOSSPR composites(HSF/BPOSSPR)are significantly enhanced.The linear ablation rate and mass ablation rate of CF/BPOSSPR are as low as 0.003 mm/s and 0.0354 g/s;those of HSF/BPOSSPR are 0.119 mm/s and 0.0264 g/s.The ablation-resistance mechanism of BPOSSPR composites is mainly due to the formation of ceramic thermal barrier layers under high temperature conditions,such as B_(2)O_(3),SiO_(2),borosilicate glass,SiC,which might play an effective role in protecting against heat flow erosion.As a result of these ex-cellent properties,the innovative heat shielding BPOSSPR composites could offer the ability to tolerate harsher environment in future aerospace applications.

Correction to:Organic photodiodes:device engineering and applications

Correction to:Frontiers of Optoelectronics(2022)15:49 https://doi.org/10.1007/s12200-022-00049-w Following publication of the original article[1],the authors identifed an error in the author name of Tong Shan.The given name and family name were erroneously transposed.The incorrect author name is:Shan Tong.The correct author name is:Tong Shan.The author group has been updated above and the original article[1]has been corrected.

Evaluating the fractionation of ion-adsorption rare earths for in-situ leaching and metallogenic mechanism

The fractionation of ion adsorption rare earths(IAREs) along the depth in a shaft of a deposit at Dajishan,Jiangxi, China was comparatively evaluated using the partition values(PVs) and relative fractionation values(RFVs) of the leached rare earths(REs). It is found that both PVs and RFVs can objectively reflect the migration and fractionation of REs, but RE content and abrasion pH could not. However, the RFVs can provide more information to quantitatively evaluating the migration and fractionation characteristics of REs along the selected direction and region than PVs could, which is of significance for designing the optimal procedures of in-situ leaching based on the determined flow direction of injecting solution. It is demonstrated that the migration of Ce, Pr, and Nd along the depth direction is inert, and that of REs post Sm and Y is active. Meanwhile, the migration of La shows region characteristics which is active in the upper and inert in lower region. More interesting, the dependence of RFVs on atomic number of REs displays a tetrad group variation trend. However, the fractionation of REs among clay minerals with different particle sizes is not evident, especially for the clay in the bottom region. These results indicate that the migration and fractionation of REs not only are dominated by the adsorption of their hydrated ions, but also rely on their hydrolysis tendency, which provide information for understanding the metallogenic mechanism of IAREs.

Radiative properties of alumina/aluminum particles and influence on radiative heat transfer in solid rocket motor

The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is lacking.In addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom studied.In this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at macroscale.The effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate method.Then a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale motor.The convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the throat.As the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.

纤维增强酚醛体系固化机理研究及动力学建模

纤维增强酚醛复合材料以其优异的耐高温和耐烧蚀性能成为固体发动机喷管的理想材料.增强纤维的物理和化学特性会显著影响酚醛树脂(PF)的固化反应,为探究纤维增强酚醛体系固化反应与纯酚醛的区别,并获得高硅氧玻璃纤维/酚醛预浸料和碳纤维/酚醛预浸料的固化模型,本文采用差示扫描量热法(DSC),分别对纯酚醛树脂、高硅氧玻璃纤维/酚醛、碳纤维/酚醛进行了动态DSC实验.针对三种材料的动态DSC测量结果,通过等转变动力学方法,确定了3个反应体系的活化能随固化过程的变化规律,并通过引入动力学补偿效应,获得了3种材料的固化反应机理.结果表明,增强纤维会改变酚醛树脂的固化反应机理,三者的活化能和指前因子都不同,纯酚醛树脂为自催化模型,高硅氧玻璃纤维/酚醛预浸料为由自催化反应转变为N阶反应的两步模型,碳纤维/酚醛预浸料为由自催化反应转变为N阶反应的三步模型.

Organic photodiodes:device engineering and applications

Organic photodiodes(OPDs)have shown great promise for potential applications in optical imaging,sensing,and communication due to their wide-range tunable photoelectrical properties,low-temperature facile processes,and excellent mechanical fexibility.Extensive research work has been carried out on exploring materials,device structures,physical mechanisms,and processing approaches to improve the performance of OPDs to the level of their inorganic counterparts.In addition,various system prototypes have been built based on the exhibited and attractive features of OPDs.It is vital to link the device optimal design and engineering to the system requirements and examine the existing defciencies of OPDs towards practical applications,so this review starts from discussions on the required key performance metrics for diferent envisioned applications.Then the fundamentals of the OPD device structures and operation mechanisms are briefy introduced,and the latest development of OPDs for improving the key performance merits is reviewed.Finally,the trials of OPDs for various applications including wearable medical diagnostics,optical imagers,spectrometers,and light communications are reviewed,and both the promises and challenges are revealed.

Plasmodium yoelii infection inhibits murine leukaemia WEHI-3 cell proliferation in vivo by promoting immune responses

Background:Leukaemia is a malignant leukocyte disorder with a high fatality rate,and current treatments for this disease are unsatisfactory.Therefore,new therapeutic strategies for leukaemia must be developed.Malaria parasite infection has been shown to be effective at combating certain neoplasms in animal experiments.This study is to demonstrate the anti-leukaemia activity of malaria parasite Plasmodium yoelii(P.yoelii)infection,.Methods:In this study,the proportion of CD3,CD19,CD11b and Mac-3 cells was analysed by flow cytometry;the levels of IFN-γand TNF-αin individual serum samples were measured by enzyme-linked immunosorbent assay,and the phagocytic activity of macrophages and natural killer(NK)cell activity were measured by flow cytometry.Results:We found that P.yoelii infection significantly attenuated the growth of WEHI-3 cells in mice.In addition,tumor cell infiltration into the murine liver and spleen was markedly reduced.We also demonstrated that malaria parasite infection elicited anti-leukaemia activity by promoting immune responses,including increasing the surface markers of T cells(CD3)and B cells(CD19);decreasing the surface markers of monocytes(CD11b)and macrophages(Mac-3);inducing the secretion of IFN-γand TNF-α;and increasing NK cell and macrophage activity.Conclusions:Malaria parasite infection significantly decreases the number of myeloblasts and inhibits neoplasm proliferation in mice.In addition,malaria parasite infection inhibits murine leukaemia by promoting immune responses.

Interaction mechanism between BaZrO_(3)/Y_(2)O_(3) refractory and Ti_(2)Ni alloy melts

The titanium alloys with highly chemical activity require stable crucible refractories that can withstand the erosion of alloy melts.The phase composition and microstructure are crucial factors that affect the stability of the refractory crucible.The effect of Y_(2)O_(3) on the composition and microstructure of BaZrO_(3) crucible was systematically investigated,and the improved mechanism of the stability of BaZrO_(3)/Y_(2)O_(3) crucible was clarified in comparison with the BaZrO_(3) crucible.The results showed that the erosion layer thickness of the BaZrO_(3)/Y_(2)O_(3) crucible was only 63μm,which was far less than that in the BaZrO_(3) crucible(485μm),and the erosion layer in the BaZrO_(3)/Y_(2)O_(3) crucible also exhibited a higher density than that in the BaZrO_(3) crucible.During the sintering,Y_(2)O_(3) could improve the densification of the BaZrO_(3) crucible due to the solid solution effect between Y_(2)O_(3) and ZrO_(2),which also caused the evaporation of BaO,resulting in the generation of a Y_(2)O_(3)(ZrO_(2))film on the surface of the crucible.Furthermore,the Y_(2)O_(3)(ZrO_(2))had higher thermodynamic stability than Y_(2)O_(3),confirming that the BaZrO_(3)/Y_(2)O_(3) crucible with high density exhibited a superior erosion resistance to titanium alloys.This dual-phase structure provides a strategy to design a long-life and stable refractory for melting titanium alloys.