Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.

A candidate protective factor in amyotrophic lateral sclerosis:heterogenous nuclear ribonucleoprotein G

Heterogenous nuclear ribonucleoprotein G is down-regulated in the spinal cord of the Tg(SOD1*G93A)1Gur(TG)amyotrophic lateral sclerosis mouse model.However,most studies have only examined heterogenous nuclear ribonucleoprotein G expression in the amyotrophic lateral sclerosis model and heterogenous nuclear ribonucleoprotein G effects in amyotrophic lateral sclerosis pathogenesis such as in apoptosis are unknown.In this study,we studied the potential mechanism of heterogenous nuclear ribonucleoprotein G in neuronal death in the spinal cord of TG and wild-type mice and examined the mechanism by which heterogenous nuclear ribonucleoprotein G induces apoptosis.Heterogenous nuclear ribonucleoprotein G in spinal cord was analyzed using immunohistochemistry and western blotting,and cell proliferation and proteins(TAR DNA binding protein 43,superoxide dismutase 1,and Bax)were detected by the Cell Counting Kit-8 and western blot analysis in heterogenous nuclear ribonucleoprotein G siRNA-transfected PC12 cells.We analyzed heterogenous nuclear ribonucleoprotein G distribution in spinal cord in the amyotrophic lateral sclerosis model at various time points and the expressions of apoptosis and proliferation-related proteins.Heterogenous nuclear ribonucleoprotein G was mainly localized in neurons.Amyotrophic lateral sclerosis mice were examined at three stages:preonset(60-70 days),onset(90-100 days)and progression(120-130 days).The number of heterogenous nuclear ribonucleoprotein G-positive cells was significantly higher in the anterior horn of the lumbar spinal cord segment of TG mice at the preonset stage than that of control group but lower than that of the control group at the onset stage.The number of heterogenous nuclear ribonucleoprotein G-positive cells in both central canal and surrounding gray matter of the whole spinal cord of TG mice at the onset stage was significantly lower than that in the control group,whereas that of the lumbar spinal cord segment of TG mice was significantly higher than that in the control group at preonset stage and significantly lower than that in the control group at the progression stage.The numbers of heterogenous nuclear ribonucleoprotein G-positive cells in the posterior horn of cervical and thoracic segments of TG mice at preonset and progression stages were significantly lower than those in the control group.The expression of heterogenous nuclear ribonucleoprotein G in the cervical spinal cord segment of TG mice was significantly higher than that in the control group at the preonset stage but significantly lower at the progression stage.The expression of heterogenous nuclear ribonucleoprotein G in the thoracic spinal cord segment of TG mice was significantly increased at the preonset stage,significantly decreased at the onset stage,and significantly increased at the progression stage compared with the control group.heterogenous nuclear ribonucleoprotein G expression in the lumbar spinal cord segment of TG mice was significantly lower than that of the control group at the progression stage.After heterogenous nuclear ribonucleoprotein G gene silencing,PC12 cell survival was lower than that of control cells.Both TAR DNA binding protein 43 and Bax expressions were significantly increased in heterogenous nuclear ribonucleoprotein G-silenced cells compared with control cells.Our study suggests that abnormal distribution and expression of heterogenous nuclear ribonucleoprotein G might play a protective effect in amyotrophic lateral sclerosis development via preventing neuronal death by reducing abnormal TAR DNA binding protein 43 generation in the spinal cord.

Multivariate adaptive regression splines analysis for 3D slope stability in anisotropic and heterogenous clay

Little research can be found in relation to the stability of anisotropic and heterogenous soils in three dimensions.In this paper,we propose a study on the three-dimensional(3D)undrained slopes in anisotropic and heterogenous clay using advanced upper and lower bounds finite element limit analysis(FELA).The obtained stability solutions are normalized,and presented by a stability number that is a function of three geometrical ratios and two material ratios,i.e.depth ratio,length ratio,slope angle,shear strength gradient ratio and anisotropic strength ratio.Numerical results are compared with experimental data in the literature,and charts are presented to cover a wide range of design parameters.Using the multivariate adaptive regression splines(MARS)analysis,the respective influence and sensitivity of each design parameter on the stability number and the failure mechanism are investigated.An empirical equation is also developed to effectively estimate the stability number.

Traffic Flow Prediction with Heterogenous Data Using a Hybrid CNN-LSTM Model

Predicting traffic flow is a crucial component of an intelligent transportation system.Precisely monitoring and predicting traffic flow remains a challenging endeavor.However,existingmethods for predicting traffic flow do not incorporate various external factors or consider the spatiotemporal correlation between spatially adjacent nodes,resulting in the loss of essential information and lower forecast performance.On the other hand,the availability of spatiotemporal data is limited.This research offers alternative spatiotemporal data with three specific features as input,vehicle type(5 types),holidays(3 types),and weather(10 conditions).In this study,the proposed model combines the advantages of the capability of convolutional(CNN)layers to extract valuable information and learn the internal representation of time-series data that can be interpreted as an image,as well as the efficiency of long short-term memory(LSTM)layers for identifying short-term and long-term dependencies.Our approach may utilize the heterogeneous spatiotemporal correlation features of the traffic flowdataset to deliver better performance traffic flow prediction than existing deep learning models.The research findings show that adding spatiotemporal feature data increases the forecast’s performance;weather by 25.85%,vehicle type by 23.70%,and holiday by 14.02%.

Extrahepatic bile duct reconstruction in pigs with heterogenous animal-derived artificial bile ducts:A preliminary experience

BACKGROUND Extrahepatic biliary duct injury(BDI)remains a complicated issue for surgeons.Although several approaches have been explored to address this problem,the high incidence of complications affects postoperative recovery.As a nonimmunogenic scaffold,an animal-derived artificial bile duct(ada-BD)could replace the defect,providing good physiological conditions for the regeneration of autologous bile duct structures without changing the original anatomical and physiologic conditions.AIM To evaluate the long-term feasibility of a novel heterogenous ada-BD for treating extrahepatic BDI in pigs.METHODS Eight pigs were randomly divided into two groups in the study.The animal injury model was developed with an approximately 2 cm segmental defect of various parts of the common bile duct(CBD)for all pigs.A 2 cm long novel heterogenous animal-derived bile duct was used to repair this segmental defect(group A,ada-BD-to-duodenum anastomosis to repair the distal CBD defect;group B,ada-BD-to-CBD anastomosis to repair the intermedial CBD defect).The endpoint for observation was 6 mo(group A)and 12 mo(group B)after the operation.Liver function was regularly tested.Animals were euthanized at the above endpoints.Histological analysis was carried out to assess the efficacy of the repair.RESULTS The median operative time was 2.45 h(2-3 h),with a median anastomosis time of 60.5 min(55-73 min).All experimental animals survived until the endpoints for observation.The liver function was almost regular.Histologic analysis indicated a marked biliary epithelial layer covering the neo-bile duct and regeneration of the submucosal connective tissue and smooth muscle without significant signs of immune rejection.In comparison,the submucosal connective tissue was more regular and thicker in group B than in group A,and there was superior integrity of the regeneration of the biliary epithelial layer.Despite the advantages of the regeneration of the bile duct smooth muscle observed in group A,the effect on the patency of the ada-BD grafts in group B was not confirmed by macroscopic assessment and cholangiography.CONCLUSION This approach appears to be feasible for repairing a CBD defect with an ada-BD.A large sample study is needed to confirm the durability and safety of these preliminary results.

Application of Heterogenous Catalysis with TiO2 Photo Irradiated by Sunlight and Latter Activated Sludge System for the Reduction of Vinasse Organic Load

Vinasse is the main residue generated during alcohol, sugar and blue rum production by fermentation process. This residue is effluent that could cause serious environmental pollution due to high organic load when is not treated adequately. The aim of this work consists of evaluating the efficiency and application of heterogeneous photocatalysis with TiO2, followed by a biological treatment (activated sludge system) to reduce organic load in the referred effluent. Complete factorial designs indicated the best experimental conditions subsequent to photacatalytic and biological treatments providing a reduction of non-purgeable organic carbon (NPOC) as a variable response. After the photocatalytic process, the sample from the best experiment condition was treated by a biological process in order to verify the degradation efficiency of the effluent organic matter studied according to the hybrid system (Advanced Oxidation Process—Acti- vated Sludge System). This system, which presented more efficiency, had a photochemical treatment of 180 minutes carried out in aerated solutions, pH 9 and effluent in natura, while the biological treatment was performed at pH 8 and sludge concentration of 5 gL–1. The reduction of biochemical oxygen demand (BOD) was >80%.

Significance of the antigenic epitopes in heterogenous nuclear ribonucleoproteins-Ⅰfor the diagnosis and prognosis of systematic sclerosis

To assess the presence of autoantibodies against epitopes of heterogenous nuclear ribonucleoprotein- Ⅰ （hnRNP- Ⅰ ） in systematic sclerosis （SSc） and to analyze their clinical significance, polypeptides of hnRNP- Ⅰ were designed by biological technical software and analyzed with both the Wonderful Biology Information System and DNA Star-Protean Analysis Software at the same time. In these ways, two polypeptides of hnRNP- Ⅰ were obtained based on their amino acid sequences, folding features, hydrophilic, curl style, dough kneading sensation and the possibility on the surface of proteins. They are named as hnRNP- Ⅰ -1 （ NVKYNNDKSRDYTRPDLPSGDSQPSLDQT, 264-292 aa） and hnRNP- Ⅰ -2 （QLP4REGQEDQGLTKDYGNSOL, 441-461 aa）, simply designated as Ⅰ -1 and Ⅰ -2. The autoantibodies against hnRNPs were detected by means of ELISA using the synthetic epitopes polypeptides as antigen. It was found that the positive rate of detection for anti- Ⅰ -1 and anti- Ⅰ -2 autoantibodies were rather higher in SSc patients than that in other CTDs and the sensitivities and specificities of the testing with ELISA for anti- Ⅰ -1 and anti- Ⅰ -2 antibodies in SSc patients were 47.62%/93.43% and 38.1%/ 91.08%, without any significant difference between these two groups of testings. Also, there was no significant difference in the clinical features and laboratory findings, such as age, involvements in digestive and respiratory tracts and erythrocyte sedimentation rate etc., between the anti- Ⅰ -Ⅰ-positive and -negative groups in SSc patients. However, the hnRNP- Ⅰ -autoantibody-positive group of patients had obviously shorter duration of disease course compared with that of the autoantibody-negative group. Anti- Ⅰ -1 and anti- Ⅰ -2 autoantibodies also had no association with antinuclear antibody, anti-Sc170 and anti-centromere antibody （ACA） in SSc patients. So, it is apparent that the autoantibodies related with SSc may act through different pathways in the pathogenesis of SSc, and the hnRNP- Ⅰ autoantibody is a new type antibody occuring during the early stage of disease and appearing to have diagnostic and prognostic significances.

Strategies for enhancing peroxymonosulfate activation by heterogenous metal-based catalysis:A review

Sulfate radical-advanced oxidation processes(SR-AOPs)are promising technologies for organic pollutants elimination.Heterogeneous metal-based catalysis has been widely studied and applied to activate peroxymonosulfate(PMS)for producing sulfate radicals.Developing highly efficient catalysts is crucial for future extensive use.Importantly,the catalytic activity is mainly determined by mass and electron transfer.This paper aims to overview the recent enhancement strategies for developing heterogeneous metalbased catalysts as effective PMS activators.The main strategies,including surface engineering,structural engineering,electronic modulation,external energy assistance,and membrane filtration enhancement,are summarized.The potential mechanisms for improving catalytic activity are also introduced.Finally,the challenges and future research prospects of heterogenous metal-based catalysis in SR-AOPs are proposed.This work is hoped to guide the rational design of highly efficient heterogenous catalysts in SR-AOPs.

Efficient homogenous catalysis of CO_(2) to generate cyclic carbonates by heterogenous and recyclable polypyrazoles

The cycloaddition between CO_(2)and epoxides to produce cyclic carbonate is an attractive and efficiency pathway for the utilization of CO_(2)as C1 source.The development of catalyst to mediate cycloaddition between CO_(2)and epoxides at low temperature and pressure is still a challenge.Herein,a series of polypyrazoles with glass transition temperature(T_(g))in the range of 42.3-52.5℃ were synthesized and served as catalyst to mediate the cycloaddition of CO_(2)and epoxides by the assistant of tetrabutylammonium bromide.The catalytic behaviors of polypyrazole on the model cycloaddition of CO_(2)to epichlorohydrin,including the reaction parameters optimization and versatility were investigated in detail,and excellent yield(99.9%)and selectivity(99%)were obtained under the optimized reaction conditions of70℃ and 1.0 MPa for 6.0 h.Noteworthily,the polypyrazole acts as homogeneous catalyst during reaction(higher than T_(g)).And under room temperature,polypyrazoles can be easily separated and recovered,which is a promising feature of a heterogeneous catalyst.Furthermore,the reaction mechanism was proposed.The DFT calculation suggested that the formation of hydrogen bond between pyrazole and epoxide greatly reduced the energy barrier,which play an important role in promoting CO_(2)cycloaddition.

Highly active and stable porous polymer heterogenous catalysts for decomposition of formic acid to produce H_2

Formic acid(FA)has attracted extensive attention as a hydrogen storage material.Here,we develop two heterogeneous catalysts based on porous organic polymers(POPs).After loading the Ru species,the catalyst bearing the triphenylphosphine ligand showed excellent performance in terms of activity and stability for the decomposition of FA to produce hydrogen.

Distributed Optimization for Heterogenous Second⁃Order Multi⁃Agent Systems

A continuous⁃time distributed optimization was researched for second⁃order heterogeneous multi⁃agent systems.The aim of this study is to keep the velocities of all agents the same and make the velocities converge to the optimal value to minimize the sum of local cost functions.First,an effective distributed controller which only uses local information was designed.Then,the stability and optimization of the systems were verified.Finally,a simulation case was used to illustrate the analytical results.

Accelerated heterogenous ring-opening polymerization towards well-defined helical poly(N-allyl alanine)with clickable side chains

Well-defined poly(N-allyl alanine)has been synthesized by heterogenous ring-opening polymerization(HROP)of less reactive N-allyl-alanine N-carboxyanhydride,using acetic acid as the catalyst and benzylamine as the initiator,in non-polar n-hexane.Interestingly,the polymerization exhibited typical features of living polymerization though both monomer(liquid)and polymer(solid)have minimal solubility in n-hexane.The obtained polymer showed a stable helix structure independent of the temperatures screened,as evidenced by circular dichroism analysis.Also,the preliminary study demonstrated that the side chains can be post-functionalized through thiol-ene click chemistry with quantitative conversion.Together,this work provides guidance for the development of accelerated HROP of other liquid monomers bearing low reactivity.Besides,the helical and functionalizable poly(N-allyl alanine)could be a useful“clickable platform”for the design of variable biomaterials via efficient click chemistry.

Immobilized CeO_(2)@C-N Heterogenous Structures with Enhanced Dual Modal Photodynamic/Photothermal Bacterial Inactivation Under NIR Laser Irradiation

Non-antibiotic fungicides are urgently needed due to the potential threat of drug-resistant bacteria to human health.In this research,a novel antibacterial nanoplatform based on CeO_(2)@C-N has been developed to achieve rapid near-infrared(NIR)laser-induced sterilization.The prepared CeO_(2)@C-N hybrid material exhibited a nanowire-like structure,with dispersed CeO_(2)nanoparticles averaging 5 nm in size within the heterogeneous configuration.X-ray photoelectron spectroscopy(XPS)and Raman spectra revealed that the heterogenous structures have a significant amount of oxygen vacancies and defects.Notably,CeO_(2)@C-N has a narrower band gap than CeO_(2),which allows for broader absorbance extending to the NIR region.With these unique physiochemical properties,CeO_(2)@C-N could inactivate E.coli and MRSA at a low concentration(20 mg/L)under 808 nm NIR laser(1 W/cm^(2))irradiation.The excellent bactericidal activity of CeO_(2)@C-N is attributed to the combination of photodynamic and photo thermal processes,based on its excellent photo-thermal conversion property,detection of reactive oxygen species(ROS)(^(1)O_(2)and·OH)under light irradiation,and scavenger quenching experiment results.This study offers a feasible and efficient way to fabricate a highly effective antibacterial candidate.

Heterogenous glucose-stimulated insulin secretion at single islet level

Insulin secretion by pancreatic islets plays a vital role in regulating blood glucose levels.Nevertheless,the mech-anism responsible for this dynamic insulin secretion has not been completely understood,particularly at the single islet level.In this study,we have successfully developed an easy microfluidic platform that allows for the exploration of dynamic glucose-stimulated insulin secretion(GSIS)at the single islet level.With the utilization of this platform,we evaluated dynamic GSIS from single islets isolated from both normal and diabetic rats.Our results demonstrate that islets can be categorized into three types based on their dynamic GSIS:Type Ⅰ exhibits a biphasic GSIS profile with a fast first phase and flat second phase;Type Ⅱ also has a biphasic GSIS profile with a fast first phase but a slow increased second phase;Type Ⅲ displays only a slowly increased second phase and lacks a fast first phase.RNA sequencing analysis demonstrated that the cell type and exocytosis-specific genes are consistent with the proportion of cells and insulin release kinetics among the three types of islets,respectively.Moreover,our findings suggest that high expression of Atp5pb is anti-correlated with the first phase of insulin secretion.Furthermore,we revealed that diabetic islets exhibit only the type Ⅰ GSIS response,indicating a deliberate impairment of the second phase of insulin secretion.Together,this device serves as a crucial tool in the research field of islets and diabetes,allowing researchers to investigate islet functional heterogeneity and identity at the single islet level.

Efficient hydrogenolysis of fructose to 1,2-propanediol over bifunctional Ru-WO_(x)-MgO_(y) catalysts under mild reaction conditions via enhancing the chemoselective cleavage of C-C bonds

Selective conversion of fructose to 1,2-propanediol(1,2-PDO)is considered as a sustainable and cost-effective alternative to petroleum-based processes,however,this approach still faces challenges associated with low efficiency and harsh reaction conditions.Here,we have successfully synthesized a novel bifunctional Ru-WO_(x)-MgO_(y) catalyst through a facile'one-pot'solvothermal method.Remarkably,this catalyst exhibits exceptional catalytic performances in the conversion of fructose to 1,2-PDO under mild reaction conditions.The yield of 1,2-PDO is up to 56.2%at 140°C for 4 h under an ultra-low hydrogen pressure of only 0.2 MPa,surpassing the reported results in recent literature(below 51%).Comprehensive characterizations and density functional theory(DFT)calculations reveal that the presence of oxygen vacancies in the Ru-WO_(x)-MgO_(y) catalyst,serving as active acidic sites,facilitates the chemoselective cleavage of C-C bonds in fructose,which leads to the generation of active intermediates and ultimately resulted in the high yield of 1,2-PDO.

Oscillatory Dynamics of Heterogeneous Stem Cell Regeneration

Stem cell regeneration is an essential biological process in the maintenance of tissue homeostasis;dysregulation of stem cell regeneration may result in dynamic diseases that show oscillations in cell numbers.Cell heterogeneity and plasticity are necessary for the dynamic equilibrium of tissue homeostasis;however,how these features may affect the oscillatory dynamics of the stem cell regeneration process remains poorly understood.Here,based on a mathematical model of heterogeneous stem cell regeneration that includes cell heterogeneity and random transition of epigenetic states,we study the conditions to have oscillation solutions through bifurcation analysis and numerical simulations.Our results show various model system dynamics with changes in different parameters associated with kinetic rates,cellular heterogeneity,and plasticity.We show that introducing heterogeneity and plasticity to cells can result in oscillation dynamics,as we have seen in the homogeneous stem cell regeneration system.However,increasing the cell heterogeneity and plasticity intends to maintain tissue homeostasis under certain conditions.The current study is an initiatory investigation of how cell heterogeneity and plasticity may affect stem cell regeneration dynamics,and many questions remain to be further studied both biologically and mathematically.

Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO_(2) into carboxylic acids

The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.

Insight into the spoilage heterogeneity of meat-borne bacteria isolates with high-producing collagenase

Chilled chicken is inevitably contaminated by microorganisms during slaughtering and processing,resulting in spoilage.Cutting parts of chilled chicken,especially wings,feet,and other skin-on products,are abundant in collagen,which may be the primary target for degradation by spoilage microorganisms.In this work,a total of 17 isolates of spoilage bacteria that could secrete both collagenase and lipase were determined by raw-chicken juice agar(RJA)method,and the results showed that 7 strains of Serratia,Aeromonas,and Pseudomonas could significantly decompose the collagen ingredients.The gelatin zymography showed that Serratia liquefaciens(F5)and(G7)had apparent degradation bands around 50 kDa,and Aeromonas veronii(G8)and Aeromonas salmonicida(H8)had a band around.65 and 95 kDa,respectively.The lipase and collagenase activities were detected isolate-by-isolate,with F5 showing the highest collagenase activity.For spoilage ability on meat in situ,F5 performed strongest in spoilage ability,indicated by the total viable counts,total volatile basic nitrogen content,sensory scores,lipase,and collagenase activity.This study provides a theoretical basis for spoilage heterogeneity of strains with high-producing collagenase in meat.

Neurophysiological, histological, and behavioral characterization of animal models of distraction spinal cord injury: a systematic review

Distraction spinal cord injury is caused by some degree of distraction or longitudinal tension on the spinal cord and commonly occurs in patients who undergo corrective operation for severe spinal deformity.With the increased degree and duration of distraction,spinal cord injuries become more serious in terms of their neurophysiology,histology,and behavior.Very few studies have been published on the specific characteristics of distraction spinal cord injury.In this study,we systematically review 22 related studies involving animal models of distraction spinal cord injury,focusing particularly on the neurophysiological,histological,and behavioral characteristics of this disease.In addition,we summarize the mechanisms underlying primary and secondary injuries caused by distraction spinal cord injury and clarify the effects of different degrees and durations of distraction on the primary injuries associated with spinal cord injury.We provide new concepts for the establishment of a model of distraction spinal cord injury and related basic research,and provide reference guidelines for the clinical diagnosis and treatment of this disease.

Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano‑Aerogel via Abundant Nano‑Sized Cavities and Attenuation Interfaces

Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.