Search

In order to improve the convergence and clock speed of DFxLMS adaptive filter, a hardware architecture of fine-grained retiming DFxLMS (HS-TF-RDFXLMS) filter in the form of hardware sharing transpose is proposed. Firstly, the architecture adopts delay decomposition algorithm to solve the problem that the convergence of filter decreases due to the increase of delay and output lag. Secondly, on the premise that the algorithm performance remains unchanged, the adaptive filter module and the secondary path module are transposed to further reduce the critical path to improve the clock speed of the system. The number of registers is reduced by optimizing circuit sub-module. Finally, the area/speed tradeoff of TF-RDFXLMS filter is realized by hardware sharing on the basis of constant critical path. Experimental results show that the convergence speed of the algorithm is 3.5 times that of DFxLMS algorithm, and the critical path is shortened by ([log2N]+1)TADD. The circuit structure of adaptive filter designed in this paper is realized by Xilinx Artix7 FPGA platform. The clock speed of HS-TF-RDFXLMS filter is reduced by 4.386% compared with TF-RDFXLMS filter. However, the resources of LUT and FF are saved by 10.964% and 28.322% respectively. The power consumption is 150.73 mW. This improves the performance of the system.

In this paper, a feed-forward back-propagation artificial neural network (ANN) is proposed to correlate and predict the thermal conductivity from the triple point temperature up to 0.98 times critical temperature (

Satellite free-space optical (FSO) communication is very promising in improving the bandwidth and capacity of space information networks in the future. However, the inter-satellite transmission distance of over 1000 km leads to unstable optical beam pointing, acquisition, and tracking and then generates optical power jitter by a large margin before detection–demodulation. Therefore, it is difficult to realize high-stability and long-time FSO communication between satellites due to the generated bit error rate (BER) by jitter. In this paper, we report an autonomously self-designed and high-integration laser communication payload (LCP) and on-orbit-demonstrated inter-satellite 145 min, zero-BER FSO stable communication with a line rate of 2.8 Gbps. Moreover, based on the inter-satellite laser communication link, a video phone was clearly implemented for more than 10 min, and authentic user data transmitted 459,149 packets, achieving results of zero-packet loss. Summarily, this on-orbit experiment demonstrated an excellent performance of the LCP owing to the distinctive design of integrating a high-power amplifier and low-noise amplifier optical amplification function. Our space mission was successfully completed, and the on-orbit demonstration results may offer a significant reference for the field of satellite laser communication and space information networks.

A series of soluble thermosetting polyimide resins containing benzoxazole structure were synthesized by two-step polymerization using 4-phenylethynylphthalic anhydride (4-PEPA) as the end-capping reagent, 2-(4-aminophenyl)-5-aminobenzoxazole (BOA) and 3,4′-diaminodiphenyl ether (3,4′-ODA) as the aromatic diamines, and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) as the aromatic dianhydride. The imide oligomers were characterized by employing Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), solubility tests and rheological measurements. Thermosetting polyimides derived from the imide oligomers were then produced via a thermal cross-linking reaction of the phenylethynyl group. The thermal and mechanical properties of the thermosets were studied using thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMA), and mechanical property measurements. The effects of chemical architectures and molecular weights of the imide oligomers on processability, thermostability and mechanical properties were systematically investigated. The results showed that all the copolymerized imide oligomers possessed good solubility in organic and low melt viscosity, and the corresponding thermosets exhibited high glass transition temperature (up to 401°C) and 5% weight-loss temperature (up to 533°C) in an air atmosphere while excellent mechanical properties (flexural strength up to 217 MPa and elongation at break up to 11.2%). With the increase of the concentration of the benzoxazole group, the imide oligomers of PI-X-2 (-O-, -BO-, -B-) exhibited less solubility and higher minimum melt viscosity but improved glass transition temperature after curing and mechanical properties of their thermosets.

In this study, three adamantane-containing diamines, i.e. 1,3-bis(4-aminophenyl) adamantane (ADMDA), 1,3-bis(3,5-dimethyl-4-aminophenyl) adamantane (DMADMDA) and 1,3-bis(fluoro-aminophenyl) adamantane (FADMDA), were successfully synthesized by Friedel–Crafts alkylation reactions between 1-adamantanol and acetanilide or its analogues, followed by hydrolysis with aqueous NaOH solution. Three regio-isomers were formed in the case of FADMDA due to the occurrence of both para- and ortho-alkylation (relative to the amino groups). Three series of semi-alicyclic polyimides were subsequently produced through a conventional one-step solution polycondensation between the as-developed diamines and commercial dianhydrides. The properties of the synthesized polyimides were characterized with respect to their thermal, mechanical and optical properties. The adamantane-containing polyimides exhibited significantly high glass transition temperatures (Tg) in the range 285–440 °C, excellent optical transparency (>80% transmittance at 400 nm) and optimal thermal and mechanical properties. The substituents in diamines significantly impacted the properties of the resulting polyimides. Specifically, the polyimides from DMADMDA demonstrated higher d-spacing, higher Tg, lower coefficient of thermal expansion (CTE), better optical properties and inferior tensile properties relative to the ADMDA-derived polymers, which could be attributed to the enhanced chain rigidity and reduced inter- and intra-molecular interactions associated with the two bulky methyl groups. In contrast, the FADMDA-derived polymers exhibited lower d-spacing, lower Tg, higher CTE, higher tensile modulus and lower elongation at break than the ADMDA-based ones, due to the reduced chain linearity regularity caused by the ortho-alkylated isomers, as well as suppressed intramolecular interaction originating from the strongly electron-withdrawing fluorine atoms. The excellent comprehensive properties of the adamantane-containing polyimides render these materials promising candidates for a variety of optical and optoelectronic applications.

A novel dianhydride, 3,3′-di-tert-butyl-2,2′-dimethoxy-[1,1′-binaphthalene]-6,6′,7,7′-tetracarboxylic dianhydride (TNTDA), was prepared via a multi-step process. A model compound made using TNTDA and aniline has a dihedral angle of 75° between the two naphthalimide rings, evidenced by single crystal X-ray diffraction data. High temperature polycondensation of TNTDA with four different diamines afforded four intrinsically microporous polyimides (PIM-PIs). The fractional free volumes (FFV), surface areas, and average inter-chain distances of the polyimides were 0.181–0.214, 379–564 m2 g−1, and 0.635–0.682 nm, respectively. Furthermore, the rigid, bulky, and contorted structures of the PIM-PIs led to the formation of roughly 0.6 nm ultramicropores and roughly 1.2 nm larger micropores. The ultramicropores can improve the gas size-sieving capability of the polyimides, while the larger micropores can facilitate high permeability. Consequently, the TNTDA-based PIM-PIs showed an improved gas separation performance compared to polymers made using the benchmark monomer, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride. In particular, polymers from TNTDA and 2,6-diaminotriptycene (DAT) exhibited the best performance, with CO2/CH4 and O2/N2 separation metrics approaching or surpassing the 2008 Robeson upper bounds, because of the presence of additional ultramicropores related to the internal free volume of the triptycene moiety.

The gray centroid algorithm is usually used as the centroid locating algorithm in the free-space laser communication system. However, the limited spatial resolution of the image detector will produce homogenization effect, which results in gray quantization error. Moreover, the spot information will lost when we detecting the object with threshold. The two problems mentioned above will make the locating accuracy worse when using the conventional algorithm. In this paper, we use the squared weighting centroid with threshold algorithm combined with the hardware optimized interpolation subdivision algorithm to improve the locating accuracy. As the weight of bright pixels increased, and the spot information loss decreased due to subdivision, the locating accuracy improved significantly. The simulation results show that the locating accuracy has improved by at least 50%, and the experiment results confirmed that the tracking error (2.57μrad) using the improved algorithm is less than that (4.11μrad) of the conventional algorithm.

Low frequency oscillation is an important attribute of human brain activity, and the amplitude of low frequency fluctuation (ALFF) is an effective method to reflect the characteristics of low frequency oscillation, which has been widely used in the treatment of brain diseases and other fields. However, due to the low accuracy of the current analysis methods for low frequency signal extraction of ALFF, we propose the Fourier-based synchrosqueezing transform (FSST), which is often used in the field of signal processing to extract the ALFF of the low frequency power spectrum of the whole-time dimension. The low frequency characteristics of the extracted signal are compared with those of FSST and fast Fourier transform (FFT) through the resting-state data. It is clear that the signal extracted by FSST has more low frequency characteristics, which is significantly different from FFT.

Circular RNA circ_0136474 is a new contributor of human osteoarthritis (OA) by suppressing chondrocyte proliferation. However, its role and mechanism in OA chondrocyte injury remain ill defined. Herein, we performed real-time quantitative PCR to detect RNA expression of circ_0136474, microRNA (miR)-766-3p, and DNA methyltransferase 3A (DNMT3A) and utilized Western blotting to measure protein expression of DNMT3A, matrix metalloproteinase-1 (MMP1), MMP13, collagen II, proliferating cell nuclear antigen (PCNA) and B cell lymphoma (Bcl)-2, and Bcl-2-associated X protein (Bax). Direct interaction between miR-766-3p and circ_0136474 or DNMT3A was confirmed by bioinformatics algorithms, dual-luciferase reporter assay, and RNA immunoprecipitation. Functional experiments including cell counting kit-8 assay, flow cytometry, and special assay kits were employed to measure oxidative injury in interleukin (IL)-1β-induced OA-like chondrocytes. First, IL-1β administration induced cell viability inhibition, collagen II suppression, and promotion of MMP1 and MMP13 in human chondrocyte CHON-001 cells. Expression of circ_0136474 and DNMT3A was upregulated, and miR-766-3p was downregulated in human OA cartilages and IL-1β-induced CHON-001 cells. Functionally, both blocking circ_0136474 and upregulating miR-766-3p could rescue cell viability and levels of PCNA, Bcl-2, reduced glutathione (GSH), and total superoxide dismutase (SOD), and attenuate apoptosis rate and levels of Bax, reactive oxygen species (ROS), and lipid peroxidation malondialdehyde (MDA). Mechanically, circ_0136474 served as miR-766-3p sponge to govern miR-766-3p-targeted DNMT3A expression. Accidently, restoring DNMT3A counteracted the miR-766-3p upregulation role, and silencing miR-766-3p weakened circ_0136474 knockdown effect in IL-1β-induced CHON-001 cells. In conclusion, exhausting circ_0136474 could mitigate OA chondrocyte oxidative injury through regulating miR-766-3p/DNMT3A axis.

Novel dibenzodioxane-containing dianhydride (MMBMDA) and diamine (FDBDA and MMBDA) monomers with sterically hindered contortion sites and pendent fluorene or trimethylbenzene moieties were prepared using 4-methylcatechol as a major reactant. High temperature polycondensation of these monomers and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) enabled the synthesis of intrinsically microporous polyimides (PIM-PI) with adequately high molecular weights. The surface area, fractional free volume, and d-spacing of these PIM-PIs were 385–543 m2 g-1, 0.179-0.212, and 0.672-0.683 nm, respectively, following the order of MMBMDA-FDBDA > MMBMDA-MMBDA > 6FDA-FDBDA > 6FDA-MMBDA. Moreover, the high rigidity of MMBMDA-based PIM-PIs induced the formation of ultramicropores (

The dynamic fracture behavior of 3D printed nacre-like composites was fully characterized by performing three-point bending dynamic fracture experiments. Nacre-like specimens with brick and mortar microstructures were fabricated with dual-material 3D printing technology. A brittle rigid material and a rubber-like material were selected for the brick layers and adhesive of the composite, respectively. First, two crack propagation paths of specimens under impact loading were observed. The dynamic behavior of the specimen under three-point bending impact loading showed a sensitivity to the impact velocity. Then, the influences of the brick aspect ratio and adhesive thickness on the fracture failure were determined. The results showed that for the case of brick aspect ratio of 1, the peak force and peak effective surface energy increase with increasing adhesive thickness, meaning that the specimen with a larger adhesive thickness had a greater bearing capacity. For the case of brick aspect ratio of 3, when the adhesive thickness was small, the nacre-like composites exhibited a lower bearing capacity than the rigid bulk material under impact loading. However, as the adhesive thickness increased, the bearing capacity and fracture toughness of the composite improved and ultimately exceeded those of the rigid bulk material. For the specimens with a small brick aspect ratio, the cracks propagated primarily along the soft adhesive, whereas for the specimens with a large brick aspect ratio, the cracks were more likely to propagate through the hard brick. Additionally, a plateau appeared in the load-displacement curves of the specimens with a large brick aspect ratio.

In order to improve the interfacial compatibility between the fibers and epoxy resins, polyimide (PI) fibers were modified using oxygen plasma with various treatment powers. The properties of PI fibers before and after surface modification were comparatively characterized according to their chemical composition, surface morphology, surface free energy, single filament tensile strength, and interfacial shear strength (IFSS). Most of the fiber properties, including the ratio of oxygen to nitrogen, oxygen concentration, surface free energy, and IFSS firstly increased with the plasma power, and then decreased when the plasma power was higher than 120 W. With a plasma power of 120 W, the oxygen concentration and the ratio of oxygen to carbon atoms (O/C) was 26% (22% for untreated fiber) and 0.38 (0.28 for untreated fiber), respectively. Meanwhile, the values of surface free energy and IFSS were 89% and 30% higher than those for untreated fiber, respectively. Furthermore, the values of single filament tensile strength for modified fibers were only 2.3% lower than those for pristine one. These results indicated that the compatibility between PI fibers and epoxy resins was greatly improved without compromising mechanical properties.

A series of imide resins were prepared using 2,3,3′,4′-oxydiphthalic dianhydride, 4-phenylethynylphthalic anhydride, and aromatic diamines (1, 3-bis(3-aminophenoxy), 3,4′-oxyaniline, 2,2′-bis (trifluoromethyl) benzidine, and m-phenylenediamine) as starting materials. These imide oligomers were characterized by means of Fourier transform infrared spectroscopy, differential scanning calorimetry, intrinsic viscosity measurements, and rheological measurements. Some of these oligomers exhibited low (2 h at 250°C) melt viscosity, which was highly desirable for resin transfer molding process. Thermosetting polyimides (PIs) were then produced from these oligomers via thermal cross-linking reaction of phenylethynyl group. The properties of the thermosets were studied using tensile and flexural testing, dynamic mechanical thermal analysis, and thermogravimetric analysis. The cured PIs exhibited a good combination of thermal and mechanical properties, with a tensile strength of 31–76 MPa, flexural strength of 38–142 MPa, glass transition temperatures of 233–358°C, and 5% weight loss temperatures of 540–545°C under nitrogen atmosphere.

This paper proposes an enterprise-level document management system integration solution, which can effectively solve the problems of the coexistence of multiple document management systems in enterprises and public institutions, the repeated collection of document data and the inefficient access application. The solution also can effectively support the data security and confidentiality of enterprises and public institutions. The core idea of the integration solution is to realize the application integration between the document integration application system and the document information management systems by taking the document classification collection management regulations as the management basis, taking the document information integration application system as the technical carrier, and adopting the SOA technology. The integration solution has been proved to be effective in practice, with significant application value and promotion value.

The image obtained from space-based vision system has increasingly high frame frequency and resolution, and field of view is also growing. Due to the dramatic increase of data scale and the restriction of channel bandwidth between satellite and ground, on-orbit data compression becomes the core of on-satellite data processing. The paper analyzes the new generation static image compression standard JPEG2000 and the key two-dimensional (2D) discrete wavelet transform (DWT) technology. Then an FPGA (Field Programmable Gate Array)implement method for 2D integer wavelet transform is designed. It adopts the spatial combinative lifting algorithm (SCLA), which realizes the simultaneous transformation on rows and columns. On this basis, the paper realizes wavelet decomposition for images with a resolution of 6576*4384 (which is divided into 1024*1024) on the FPGA platform. In particular, the test platform is built in ISE14.7 simulation software, and the device model is xc5vfx100t. The design has passed the FPGA verification. In order to verify the correctness of the algorithm, the results are compared with that obtained by running matlab code. The experimental results show that the design is correct and the resource occupancy rate is low.

Highly soluble phenylethynyl-endcapped isoimide oligomers were synthesized using 2,3,3′,4′-biphenyltetracarboxylic dianhydride (3,4′-BPDA) and aromatic diamines as the monomers, 4-phenylethynyl phthalic anhydride (4-PEPA) as the end-capping reagent, and trifluoroacetic anhydride as the dehydrating agent; then high performance thermosetting polyimides and composites were produced from these oligomers via the thermal crosslinking reaction of the phenylethylnyl group and the material properties were fully investigated. A series of isoimide oligomers with different molecular weights and a variety of chemical architectures were prepared by polycondensation of 3,4′-BPDA, 4-PEPA, and aromatic diamines including m-phenylenediamine (m-PDA), 2,2′-bis(trifluoromethyl)benzidine (TFMB), and 3,4′-oxydianiline (3,4′-ODA), followed by cyclization with trifluoroacetic anhydride. These isoimide oligomers were characterized by means of gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), rheological measurements, intrinsic viscosity measurement, and solubility tests. Compared to their imide analogues, isoimide oligomers showed much higher solubility in low boiling point solvents, and slightly lower melt viscosity, which can be attributed to their unique asymmetric architecture. These resins were formulated into thermosetting polyimides and composites by thermal crosslinking of the phenylethynyl group and conversion from isoimide to imide at elevated temperatures. The properties of the thermosets and composites were studied using mechanical property measurements, dynamic mechanical thermal analysis (DMTA), and thermogravimetric analysis (TGA). The cured polyimides exhibited extremely high glass transition temperatures (Tg) up to 467 °C, and 5% weight loss temperatures (T5%) up to 584 °C in a nitrogen atmosphere. The polyimide/quartz fiber composites possessed excellent high temperature mechanical properties due to the high glass transition temperatures of matrix resins.

Thermal barrier coating systems with different bond coats were fabricated on polymer matrix composites via the air plasma spray process. During a thermal shock test at 400 °C, Zn and Al interlayers were helpful in improving the thermal shock resistance of coatings due to the low melting point. The coating system consisted of a soft zinc layer as a bond coat, and YSZ as a top coat exhibited the best thermal shock resistance, attributed to the lower residual stress and lower thermal stress in the Zn interlayer. The failure mechanism of the coating system was mainly ascribable to the residual stress derived from the deposition process, thermal stress, and further damage of the substrate.

ZrO2-CeO2 mixed oxides were synthesized via sol-gel process. Thermal stability, structure and morphology of samples were investigated by powder X-ray diffraction, FT-Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. In this approach, the solvent composition and Zr/Ce molar ratio have great influences on the structure and morphology of final products. With decreasing water content in the mixed solvent, specific surface area of powders increased and the single tetragonal phase was obtained. Only when the volume ratio of water and ethanol and the Zr/Ce molar ratio were 1:1, tetragonal t ''-Zr0.5Ce0.5O2 could be stabilized in powders at temperature as high as 1000 degrees C. Meanwhile, tetragonal (t') and (t '') phases coexisted in Zr0.5Ce0.5O2 solid solution without peak splitting after calcination at 1100 degrees C, further transforming into cubic and tetragonal (t') phases at 1200 degrees C. The effective activation energy for Zr0.5Ce0.5O2 nanocrystallite growth during annealing is about 5.24 +/- 0.15 kJ/mol. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.

Thermal barrier coating on the polyimide matrix composites was successfully fabricated at 400 degrees C via the combined sol-gel/sealing treatment process. In this approach, zirconia coating was firstly deposited onto substrate by sol-gel process, followed by penetration of aluminum phosphate into the final coating. Sealing mechanisms of phosphate sealant were based on the adhesive binding of phosphates and the chemical bonding. After thermal cycling at 400 degrees C for 135 cycles, no apparent delaminations and spallations appeared in the ZrO2/phosphates dual coating, and the average bonding strength was 5.83 MPa. Thermal oxidation of substrate coated with the ZrO2/phosphates dual coating could be retarded at about 900 degrees C. Crown Copyright (C) 2012 Published by Elsevier B. V. All rights reserved.

In this investigation, Zr1−x Ce x O2 coatings were fabricated on quartz fiber reinforced polyimide matrix composites via sol–gel process at 400 °C. The phase evolution, structural and morphological characteristic of specimens were investigated by differential scanning calorimetric, Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy. The significant phase evolution of final powders with the decreasing Zr/Ce molar ratio could be observed as follows: tetragonal (t′) → cubic + tetragonal (t′) → tetragonal (t″). BET specific surface areas of powders exhibited a decreased tendency with the increasing calcination temperature as well as the decreasing Zr/Ce molar ratio. The average crystallite size and the mean particle size increased with the elevated calcination temperature, while the particle size also increased with the increase in Ce content. The progressive addition of Ce could promote the sintering process and the densification of coating. Morphologies of coatings changed with the variation of the Zr/Ce molar ratio. The results indicate that Zr0.75Ce0.25O2 coating with the Zr/Ce molar ratio of 3 is a stable uniform coating with excellent adhesion.

ZrO2 powders were synthesized via sol–gel process using zirconium oxychloride octahydrate as the raw material. The effects of addition of glacial acetic acid and N,N-dimethylformamide (DMF) on crystal growth and chemical bond of powders were discussed. The structural evolution, phase transformation and morphological characteristic of powders were investigated by differential scanning calorimetric analysis (DSC), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After adding the acetic acid and DMF, the crystallite size of ZrO2 decreased from about 26.48 to 13.94 nm when calcination at 600 °C for 40 min, and the activation energy for crystal growth reduced approximately from 7.76 ± 0.62 to 2.74 ± 0.28 kJ/mol in the initial stage, while abruptly increased to 26.48 ± 1.09 kJ/mol in the later stage. The specific surface area decreased from 26.73 to 0.51 m2/g. Meanwhile, the metastable tetragonal phase could be stabilized in ZrO2 nanocrystals at 600 °C for 40 min.

Engineering Students’ innovation ability is the source of national science and technology, and it has important theoretical and practical significance for us to investigate factors of college students’ innovation ability. So, in this paper, the definition of engineering college students’ innovation ability is given firstly. Then, some influence factors of engineering college students’ innovation ability: business management ability, engineering application ability, innovation personality and cultural feature are summarized. After the test on reliability and validity, regression analysis is made for the students’ innovation ability influence factors. Finally, some suggestions are given on cultivation of college students.

Postgraduate innovative ability is one of the important abilities which postgraduate students should have. This paper discusses the connotation and influence factors of postgraduate innovative ability, which divides innovative ability into several practical abilities: innovative consciousness, scientific research ability, innovative practice ability, innovative spirit, innovative thinking, innovative methods and skills, innovative quality, innovative personality and wisdom, technical application ability, organizing ability and the team cooperation ability. The practical abilities are sorted and analyzed by theoretical analysis and empirical research, .Countermeasures and suggestions are given for postgraduate innovative ability training.

Nontransferred DC laminar plasma jets of stable flow and low impinging pressure acting on the substrate were used to heat W–Mo–Cu cast iron for phase transfer hardening of the surface layer. Substrates were heated in multipass with or without overlapping or heated with only single-pass. Surface morphologies of the molten trace and microstructure of the cross-section were observed, and the hardness distribution of the treated surface layer was examined. The surface layer of single-pass-heated specimen has an average hardness of about 900 HV0.1, while the specimen treated with multipass shows an average hardness of about 700 HV0.1, because of the heat effect from the neighboring pass treating, compared with the substrate hardness of about 300 HV0.1. The results demonstrate the stable and favorably controlled heating of the laminar plasma jet on the substrate surface and feasibility of using it as a tool for surface hardening of cast iron.

Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12}(BiLT) thin films with different thickness were successfully deposited onto fused quartz by chemical solution deposition. X-ray diffraction analysis shows that BiLT thin films are polycrystalline with (0 0 2)-preferred orientation. The dispersion of refractive indices of the BiLT thin films was investigated by the optical transmittance spectrum. The optical band gap energy was estimated from the graph of (h{nu}{alpha}){sup 2} versus h{nu}. The results show that the refractive index and band-gap energy of the BiLT thin films decrease with the films thickness.

Perovskite type PbTiO 3 films with highly [111] preferred orientation were synthesized successfully on the amorphous sapphire substrates by rf planar magnetron sputtering with an element target. Studies reveal that the film has a good alignment in the growth direction and a grain size approximately 180 nm. The mechanism of film growth was studied and the results manifested that an interfacial layer formed as self-buffer layer. This transition layer released the intrinsic stress, so that the film with excellent structure could be grown on amorphous substrates. The refractive index at room temperature was determined in the wavelength range 400–2500 nm from the transmittance at normal incidence. The dispersion was found to fit the individual dipole oscillator model very well, and the minimum refractive index of the film is deduced as 2.51.

Postgraduate innovative ability is an important indicator to measure the level and quality of postgraduate education. Postgraduate innovative ability training process is a complex system process with multi-actor participation and multi-link link. In this paper, we discuss the participation actors, training links and influence factors in the postgraduate innovative ability training process. Measures improving postgraduate innovative ability are also studied. By empirical research, based on the concept of relatively comparison we compare and analyze the factors of postgraduate innovative ability training. Countermeasures and suggestions on postgraduate innovative ability training

A synthetic approach to a two-dimensional grid polymer is proposed and the execution of initial steps is described. Pd-catalyzed coupling of (1,12-dicarba-closo-dodecaboran-1-yl)copper (10) with iodobenzene, m-diiodobenzene, and 1,3,5-triiodobenzene yielded the known 1,12-dicarba-closo-dodecaboran-1-ylbenzene (3) and the new m-bis(1,12-dicarba-closo-dodecaboran-1-yl)benzene (4) and 1,3,5-tris(1,12-dicarba-closo-dodecaboran-1-yl)benzene (1), respectively. Each arm of the trigonal connector 1 was provided with one or two sticky tentacles by conversion to 1,3,5-tris[12-((3-(ethylthio)propyl)dimethylsilyl)-1,12-dicarba-closo-dodecaboran-1-yl]benzene (7) and 1,3,5-tris[12-(bis(3-(ethylthio)propyl)methylsilyl)-1,12-dicarba-closo-dodecaboran-1-yl]benzene (8). Linear coupling of carboranyl CH terminals through a mercury atom produced very stable dimeric structures from 3 and 4. The carborane 3, its mercury-linked dimer 13, the 1:1 complex of 13 with 2,2‘-bipyridyl, and the 2:1 complex of 13 with 2,2‘-bipyrimidyl ...

Bis(cobaltacarborane) complexes bridged by fulvalene or 1,4-bis(tetramethylcyclopentadienyl)benzene ligands, and containing reactive carborane C 2 B 3 end rings, are effective synthons for the stepwise construction of air-stable multisandwich oligomers and polymers that are soluble in organic solvents. Bridge deprotonation of the end rings followed by coordination of two such units to a central transition metal (Ni IV , Co IV , Co III H) formed multilevel species having a central tetradecker sandwich linked to double-decker end units. The latter groups have exposed C 2 B 3 rings on which the same reaction sequence can be repeated to generate progressively larger oligomers

The first metallocenium metallacarboranide salts have been synthesized and isolated. The title compounds were prepared by reaction of cobaltocene and CoCl 2 or FeCl 2 with the carborane anion Et 2 C 2 B 4 H 5 - in THF solution, in which the oxidation of two M(II) metal centers to M(III) is accompanied by reduction of two B-H-B bridging protons to H 2 .

In contrast to our recently reported syntheses 2 of Co-M-Co tetradecker sandwich complexes (M=Co, Ni, Ru) via reactions of double-decker cobaltacarborane anions Cp * Co(Et 2 C 2 B 3 H 3 X) - (1 - , X=H, Me, Cl, Br, acetyl) with metal halides, reactions of the anions having X=H, Me, Et, or Cl with FeCl 2 did not produce the intended Co-Fe-Co tetradeckers.

Stacking reactions of the bridge-deprotonated Cp*Co(2,3-Et[sub 2]C[sub 2]B[sub 3]H[sub 3]-5X)[sup [minus]] complexes (X = Cl, Br, CH[sub 3], C(O)CH[sub 3], CH[sub 2]C[triple bond]CCH[sub 3], H; Cp* = [eta][sup 5]-C[sub 5]Me[sub 5]) with cobalt(II) and nickel(II) halides in THF gave, respectively, diamagnetic [Cp*Co[sup III](Et[sub 2]C[sub 2]B[sub 3]H[sub 2]X)][sub 2]Ni[sup IV] and paramagnetic [Cp*Co[sup III](Et[sub 2]C[sub 2]B[sub 3]H[sub x]X)][sub 2]Co[sup IV] tetradecker sandwich complexes. A similar reaction of the B(5)-chloro reagent using RuCl[sub 2] gave the diamagnetic trichloro complex (Cp*Co)[sub 2](2,3-Et[sub 2]C[sub 2]B[sub 3]H[sub 2]-5-Cl)(2,3-Et[sub 2]C[sub 2]B[sub 3]H-4,5[5,6]-Cl[sub 2])Ru. In all cases except the Co-Co-Co compound (X = H), the products were isolated as dark crystalline solids via chromatography on silica; decomposes on silica and was isolated via fractional crystallization from a cold solution. All of the tetradeckers are air-stable in the solid state and in solution except 3f, which is stable only as a solid. Characterization of these compounds was based on [sup 1]H, [sup 11]B, and [sup 13]C NMR (for diamagnetic species), UV-visible, and mass spectra, supported by x-ray crystallographic data on the Co-Ni-Co and Co-Co-Co dichloro compounds, the Co-Ni-Co diacetyl complex, and the Co-Ru-Co sandwich. The structurally characterized compounds are tetradecker sandwiches, slightly bent in the middle (8-15[degree]) butmore » exhibiting no significant ring slippage relative to the coordinated metal atoms. The carborane rings in these sandwiches are mutually rotated by 27-89[degree]. The electronic spectra exhibit intense absorption bands between 350 and 440 nm with extinction coefficients between 28,000 and 43,000 M[sup [minus]1] cm[sup [minus]1].« less