Preparation and Properties of Magnesium Oxysulfide Cement Based Foam Board Absorbing Material

In order to better solve the problem of electromagnetic pollution in the civil building cement,to improve the absorption capacity of magnesium oxysulfide cement based materials,and to better use sulfur oxide magnesium cement foamed sheet for improvement of electromagnetic industry,this paper uses the excellent microwave absorbing properties of ferrite and the modified sulfur oxide magnesium cement foam board,and discusses the microwave absorbing performance,aiming at improving the electromagnetic pollution in daily life.The effects of ferrite and silicon carbide doping on microwave absorption properties of modified magnesium oxysulfate cement were studied.At the same time,the wave absorbing properties of the corresponding samples were detected by bow method,and the causes of the corresponding phenomena were analyzed by scanning electron microscopy (SEM).The results show that the lowest reflectance of the material is-17.9 dB at 34.1 GHz and the average reflectance of the whole band is-15.9 dB under the target frequency band of 26.5-40 GHz.Under the action of external magnetic field,the absorbing particles are affected by magnetization force,magnetic dipole and resistance coupling,and play the absorbing effect in the cement base solidified completely in the electromagnetic field environment.The lowest reflectance is-17.3dB at 36.4GHz and the average reflectance is-14.3dB for the whole band.

Preparation and Microwave Absorption Property of Sr_2FeMoO_6 Powder

Double perovskite oxide Sr_2FeMoO_6 powder is prepared by a solid state reaction method.The microwave absorption properties of Sr_2FeMoO_6 and paraffin wax composites are studied in the frequency range of 2—18GHz at room temperature.The optimum absorption-36.7dB is achieved at 17.7GHz with a matching thickness of 5.0mm,which indicates that Sr_2FeMoO_6/paraffin composites can be potential microwave absorbers in a relatively high frequency range.The excellent microwave absorption properties are attributed to the good electromagnetic match between dielectric loss and magnetic loss.The dielectric loss is considered to be caused by orientation polarization and interfacial polarization,while the magnetic loss is caused by natural resonance in the low frequency range,eddy current loss as well as exchange resonance in the high frequency range.

Study on Hydrogen Storage Properties,Anti-Oxide Ability and Rate Limiting Step of ZrCr-Based Alloy after Introducing Cobalt as Additive

In this work,the microstructure,hydrogen storage properties,anti-oxide ability and rate limiting step of Zr(Cr_(1−x)Co_(x))_(2)(x=0,0.2,0.4 and 0.6)alloys have been investigated.After studying the crystal structure,we found that all alloy samples could show C14-type phase but the alloy sample x=0 could also show a small amount of Cr phase.Rietveld fitting showed that lattice parameter and unit cell volume of C14-type phase decreased with increasing x.After further research,it was clear that the first hydrogen absorption capacity decreased with increasing x.But introducing more Co content had a positive influence on the effective hydrogen storage capacity and cyclic hydrogen absorption and desorption properties of the alloy sample.We also found that adding Co to ZrCr_(2)alloy could improve its anti-oxide ability.In addition to this,the rate limiting step model was also studied.

Electromagnetic Shielding and Absorption Properties of Fiber Reinforced Cementitious Composites

In order to investigate the electromagnetic shielding effectiveness （SE） and absorbing properties of fiber reinforced concrete, steel fiber, carbon fiber and synthetic polyvinyl alcohol （PVA） fiber reinforced concrete were researched. The results show that with the increase of fiber Volume fraction, the SE and trend of frequency change of corresponding fiber reinforced concrete are enhanced. When the volume content of steel fiber is 3%, the SE of concrete is above 50 dB and its frequency is above 1.8 GHz. Moreover, in the range of 8-18 GHz, steel fiber, carbon fiber and PVA fiber all can improve the microwave absorption properties of concrete. The concrete with 0.5% carbon fiber can achieve the best absorbing property, the minimum reflectivity is about -7 dB; while steel fiber optimal volume fraction is 2%. The reflectivity curve of PVA fiber reinforced concrete fluctuates with the frequency, and the minimum value of the reflectivity is below -10 dB. The results show that fiber reinforced concrete could be used as EMI（electromagnetic interference） prevention buildings by attenuating and reflecting electromagnetic wave energy.

Spatial and temporal variability of colored dissolved organic matter absorption properties in the Taiwan Strait

Spatial and temporal variability of the absorption properties of colored dissolved organic matter （CDOM） in the Taiwan Strait was investigated in summer （July to August of 2006） and winter （from December 2006 to January of 2007） seasons. The CDOM absorption coefficient at 280 nm （a 280 ） showed a decreasing trend from nearshore to offshore areas while the spectral slope coefficient parameter calculated between wavelengths 275–295 nm （S 275 295 ） showed an increase, indicative of decreasing aromaticity and molecular weight of the CDOM. The average a 280 in winter （1.47 ± 0.50 m ^-1 ） was significantly higher than in summer （1.10 ± 0.41 m ^-1 ）, while the average S 275 295 in winter （26.7 ± 5.2 μm^- 1 ） was significantly lower than in summer （30.6 ± 5.5 μm^- 1 ）, demonstrating clear seasonal variation in CDOM abundance and properties in the Taiwan Strait. A three-end- member conservative mixing model showed that local terrestrial CDOM inputs from several rivers along the western coast were small （〈5%）. However, the distribution of CDOM in the Taiwan Strait is mainly controlled by water mass movement [i.e., the Zhe-min Coastal Current （ZCC） and the Kuroshio Branch Current （KBC） in winter and the South China Sea Water （SCSW） in summer]. Biological activity was also an important factor affecting the distribution of CDOM in the offshore region in summer months.

Sound Absorption Properties of Discarded Feathers/Ethylene Vinyl Acetate Copolymer Thermoplastic Composite Materials

The discarded feathers / ethylene vinyl acetate copolymer( EVA) thermoplastic composite materials was obtained with discarded feathers as reinforced material and EVA powders as matrix material by hot pressing method. Sound absorption properties were studied by changing mass ratio of discarded feathers and EVA,thickness of composite materials,hot pressing pressure and hot pressing temperature. It was found that the sound absorption properties of composite materials were good when the mass ratio of discarded feathers and EVA was 1: 1,thickness of composite materials was 30 mm,hot pressing pressure was 8 MPa,and hot pressing temperature was 80 ℃. Under the optimum conditions,the effect of composite density on sound absorption property was analyzed. In a certain range,the sound absorption property was enhanced with the decrease of the composite density.When the composite density was 0. 1g /cm^3, the maximum absorption coefficient was 0.96. Finally,the capillary theory was used to calculate the maximum sound absorption coefficient of discarded feathers / EVA thermoplastic composite materials. The good agreements of experimental results and calculated results proved the validity of the theoretical models.

Combination of a biopharmaceutic classification system and physiologically based pharmacokinetic models to predict absorption properties of baicalein in vitro and in vivo

Objective: To determine the in vitro and in vivo absorption properties of active ingredients of the Chinese medicine, baicalein, to enrich mechanistic understanding of oral drug absorption.Methods: The Biopharmaceutic Classification System(BCS) category was determined using equilibrium solubility, intrinsic dissolution rate, and intestinal permeability to evaluate intestinal absorption mechanisms of baicalein in rats in vitro. Physiologically based pharmacokinetic(PBPK) model commercial software GastroPlus~(TM) was used to predict oral absorption of baicalein in vivo.Results: Based on equilibrium solubility, intrinsic dissolution rate, and permeability values of main absorptive segments in the duodenum, jejunum, and ileum, baicalein was classified as a drug with low solubility and high permeability. Intestinal perfusion with venous sampling(IPVS) revealed that baicalein was extensively metabolized in the body, which corresponded to the low bioavailability predicted by the PBPK model. Further, the PBPK model predicted the key indicators of BCS, leading to reclassification as BCS-II. Predicted values of peak plasma concentration of the drug(C_(max)) and area under the curve(AUC)fell within two times of the error of the measured results, highlighting the superior prediction of absorption of baicalein in rats, beagles, and humans. The PBPK model supported in vitro and in vivo evidence and provided excellent prediction for this BCS class II drug.Conclusion: BCS and PBPK are complementary methods that enable comprehensive research of BCS parameters, intestinal absorption rate, metabolism, prediction of human absorption fraction and bioavailability, simulation of PK, and drug absorption in various intestinal segments across species. This combined approach may facilitate a more comprehensive and accurate analysis of the absorption characteristics of active ingredients of Chinese medicine from in vitro and in vivo perspectives.

Effect of Rare Earth Element on Microwave Absorption Properties of Nano-Lithium Ferrite

Superfine powders of nano-lithium ferrite doped with different kinds and amount of rare earth element were prepared by sol-gel method. Their photograph was taken by transmission electron microscopy. From it, we can see most of particles are less than 100 nm and average diameter of superfine powders is 50 nm. Then their microwave absorption properties are measured by power ratio method. The result indicates that microwave absorption properties of nano-lithium ferrite doped with rare earth element change obviously. Different kinds and amount of rare earth element make different influences. Magnetic hysteresis loop is surveyed by vibrating sample magnetometer. We find that there are some relationships between magnetism and microwave absorption properties.

Integrated Photothermal Nanoreactors for Effi cient Hydrogenation of CO_(2)

To alleviate the energy crisis and global warming,photothermal catalysis is an attractive way to effi ciently convert CO_(2)and renewable H_(2) into value-added fuels and chemicals.However,the catalytic performance is usually restricted by the trade-off between the dispersity and light absorption property of metal catalysts.Here we demonstrate a simple SiO 2-protected metal-organic framework pyrolysis strategy to fabricate a new type of integrated photothermal nanoreactor with a comparatively high metal loading,dispersity,and stability.The core-satellite structured Co@SiO_(2)exhibits strong sunlight-absorptive abil-ity and excellent catalytic activity in CO_(2)hydrogenation,which is ascribed to the functional separation of diff erent sizes of Co nanoparticles.Large-sized plasmonic Co nanoparticles are mainly responsible for the light absorption and conversion to heat(nanoheaters),whereas small-sized Co nanoparticles with high intrinsic activities are responsible for the catalysis(nanoreactors).This study provides a new concept for designing effi cient photothermal catalytic materials.

Microwave Absorption Properties of Polyester Composites Incorporated with Heterostructure Nanofillers with Carbon Nanotubes as Carriers

Carbonaceous nanomaterials such as carbon nanotubes （CNTs）, magnetic metal nanomaterials and semicon- ductor nanomaterials are superior candidates for microwave absorbers. Taking full advantage of the features of CNTs, nanophase cobalt and nanophase zinc oxide, whose main microwave absorption mechanisms are based on resistance loss, magnetic loss and dielectric loss, we fabricate CNT/Co and CNT/ZnO heterostructure nanocom- posites, respectively. By using the CNTs, CNT/Co nanocomposites and CNT/ZnO nanocomposites as nanofillers, composites with polyester as matrix are prepared by in situ polymerization, and their microwave absorption per- formance is studied. It is indicated that the synergetic effects of the physic properties of different components in nano-heterostructures result in greatly enhanced microwave absorption performance in a wide frequency range. The absorption peak is increased, the absorption bandwidth is broadened, and the maximum peak shifts to a lower frequency.

Theoretical Studies on the Electronic Structures and Spectral Properties of 4,4′-(Ethane-1,2-diylbis-(oxy))dibenzaldehyde and Its Polymorph

The ground state geometries, frontier molecular orbital properties, and absorption properties of 4,4′-（ethane-1,2-diylbis（oxy））dibenzaldehyde （EDO-DBDHD） and its polymorph have been studied theoretically. The density functional theory （DFT） method was employed to optimize the ground state geometries, and theoretical data reveal that EDO-DBDHD features the planar molecular conformations, in contrast to V-shaped structures of its polymorph, which agrees with the experimental data. Additionally, the absorption spectra of both compounds were predicted using time-dependent density functional theory （TDDFT）. The calculated results show that the lowest lying absorption bands of these compounds have the transition configurations of HOMO → LUMO, resulting in the transition character of π→π＊/n→π＊. The transition of HOMO → LUMO＋3 mainly contributes to the highest lying absorption bands of two compounds at 225 nm with the character of π→π＊/n→π＊.

THIN FILM PREPARATION OF AMORPHOUS Ti-Ni ALLOY AND THEIR HYDROGEN ABSORPTION PROPERTIES

Amorphous Ti_(0.88)Ni_(1.00) and Ti_(1.69)Ni_(1.00) alloy films are prepared by means of ion beam sputtering using TiNi and Ti_2Ni alloy targets, respectively. Their hydrogen absorption properties are investigated by a galvanostatic method. The results show th the discharge capacity of the Ti_(1.69)Ni_(1.00) sample is higher than that of the Ti_(0.88)Ni_(1.00) sample. And the film electrodes have high durability and long cycle life.

Design of Collagen-Based Hemostatic Material for Use in Plastic and Reconstructive Surgery

This study aims to develop collagen-based hemostatic materials. The sheet-shaped collagen sponge was manufactured by freeze-vacuum drying the aqueous solution of collagen (Col) and heat-denatured collagen (Col’) at a composition ratio of 2/1. The both sides or one side of sponge was treated with ultraviolet (UV) irradiation for 15 minutes to introduce intermolecular crosslinks between collagen molecules. The elution behavior of collagen sponge was investigated by immersing the sponge in water for a predetermined time and then by measuring the weight change. The double-sided UV-irradiated sponge showed very slow elution properties. On the other hand, the single-sided UV-irradiated sponge showed initially fast elution and subsequent very slow elution properties. Such initially fast elution of collagen molecules from the surface without UV-irradiation allows an adhesion of collagen sponge to the wound surface and results in hemostatic effect. In addition, the water absorption and retention properties of sponge were investigated by placing the hydrated sponge on a mesh for a predetermined time and then by measuring the weight change. The double-sided UV-irradiated sponge absorbed 81 times more water than own weight and showed a value of 45 times even after 7 days. The single-sided UV-irradiated sponge absorbed 80 times more water than own weight and showed a value of 39 times even after 7 days. The sponge with high water absorption and retention properties allows a wound healing effect because such sponge can absorb large amounts of blood plasma and exudates containing various cell growth factors. The double-sided UV-irradiated sponge is a good candidate for the wound dressing. On the other hand, the single-sided UV-irradiated sponge is a good candidate for the hemostatic material.

Studies on the Absorption of NO_2 by Polyethylene Glycol and the Oxidizing Properties of the Resulting Absorbent Product

PEG (Polyethylene glycol average molecular weight 300) is used as absorbent of NO2. The absorption efficiency is found to reach up to 97%. The absorbing product, PEG NO2, can be used to cleave benzyl ethers mildly and selectively to benzaldehyde and corresponding fatty alcohols, showing that PEG is a valuable oxidizing agent of benzyl ethers. As a carrier of NO2.PEG can be recovered and utilized repeatedly after the oxidation.

Effect of TiO_2 Addition to the Microwave Absortion Property of Polyaniline Micro/Nanocomposites

1 Results Recently,conducting polymers as molecular wires have attracted considerable attention because of their long conjugated length,metal conductivity and promising potential application in nanodevices.It is important to manipulate the synthesis parameters or additives used in order to produce conducting polymer showing moderate conductivity,magnetic and dielectric properties that could enhance its microwave absorbing and shielding properties.As nano-material possessing moderate conductivity,dielect...

Tunable and improved microwave absorption of flower-like core@shell MFe_(2)O_(4)@MoS_(2)(M=Mn,Ni and Zn)nanocomposites by defect and interface engineering

Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal reaction.We conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and MAPs.Furthermore,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the MAPs.By taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching thicknesses.Therefore,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.

Single-source-precursor derived Sioc ceramics with in-situ formed CNTs and core-shell structured CoSi@C nanoparticles towards excellent electromagnetic wave absorption properties

In this work,novel carbon nanotube(CNT)/CoSi/SiOC nanocomposite ceramics with in-situ formed multi-walled CNTs and core-shell structured CoSi@C nanoparticles were successfully prepared via a single-source-precursor derived ceramic approach.Ppolymericprecursor characterization as well as phase evolution,microstructure,and electromagnetic wave(EMW)absorption properties of the ceramics were investigated in detail.The results show that the in-situ formed CNTs and magnetic CoSi@C nanoparticles provide a synergistic effect on both dielectric loss(tand:)and magnetic loss,leading to outstanding EMW absorption properties of the ceramics annealed at only 1100 C.(i)For the Co feeding of 6.25 wt%,the minimum reflection loss(RLmin)is-53.1 dB,and the effective absorption bandwidth(EAB)is 4.96 GHz(7.12-12.08 GHz)with a ceramic-paraffin hybrid sample thickness of 3.10 mm,achieving full X-band coverage;(i)for the Co feeding of 9.09 wt%,the RLmin value of-66.4 dB and the EAB value of 3.04 GHz(8.40-11.44 GHz)were achieved with a thickness of only 2.27 mm.Therefore,the present CNT/CoSi/SiOC nanocomposite ceramics have potential applications for thin,lightweight,and efficient EMW absorption in harsh environments.

Influence of SiC Nanoparticles Reinforcement in Areca/Tamarind Hybrid Biopolymer Composites:Thermo-mechanical,Tribological and Morphological Features

Natural fibers are displacing synthetic fibers as reinforcement in polymer composites due to their ease of processing,low cost,wide availability,biodegradability and sustainability.In this study,industrially discarded agro-waste areca fruit husk and tamarind fruit fibers were processed and used as reinforcement with unsaturated polyester resin to create a hybrid composite containing SiC nano filler particles.The SiC nano filler particles were varied from 1 to 4 wt.%in incremental steps of 1 wt.%with a constant 40 wt.%fiber reinforcement to determine its impact on the thermo-mechanical,morphological,wear and hygro-aging properties of the developed hybrid composite.However,the composite made of 3 wt.%SiC nano filler particles exposed overall better properties with better tensile(9.137 MPa),flexural(104.056 MPa),impact(7.983 J/cm^(2)),hardness(91.577 HRRW),wear(2.2×10^(-6)µm),crystallite size(7.9 nm)and thermal stability(360℃).Further advancement in weight percent of filler material,has worsened the properties due to poor dispersion and agglomeration factors by reducing the tensile,flexural,impact and hardness characteristics by 4.6%,6.4%,4.5%and 2.18%respectively.Also,the microstructural investigation revealed the failure pattern,information on interfacial adhesion between the reinforcement,filler and matrix of the hybrid composites.In addition,the crystalline characteristics and availability of functional groups in hybrid polymer composite with 3 wt.%SiC nano filler particles were disclosed by X-ray diffraction(XRD)and Fourier Transform Infrared(FTIR)spectrum analysis,respectively.The above findings reflects that the produced hybrid polymer composites suits well for interiors of automobiles and maritime interior applications to support loads with in the specified range.

A review on carbon/magnetic metal composites for microwave absorption

At present,developing high-efficiency microwave absorption materials with properties including lightweight,thin thickness,strong absorbing intensity and broad bandwidth is an urgent demand to solve the electromagnetic pollution issues.An ideal microwave absorber should have excellent dielectric and magnetic loss capabilities,thereby inducing attenuation and absorption of incident electromagnetic radiation.Recently,various carbon/magnetic metal composites have been developed and expected to become promising candidates for high-performance microwave absorbers.In this review,we introduce the mechanisms of microwave absorption and summarize the recent advances in carbon/magnetic metal composites.Preparation methods and microwave absorption properties of carbon/magnetic metal composites with different components,morphologies and microstructures are discussed in detail.Finally,the challenges and future prospects of carbon/magnetic metal absorbing materials are also proposed,which will be useful to develop high-performance microwave absorption materials.

Defect and interface engineering in core@shell structure hollow carbon@MoS_(2)nanocomposites for boosted microwave absorption performance

Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,respectively.The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs.Furthermore,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high efficiency.And the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive MAPs.The elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching thicknesses.Therefore,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.