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Two commonly observed charge transport mechanisms in single-molecule junctions are coherent tunneling and incoherent hopping. It has been generally believed that tunneling processes yield temperature-independent conductance behavior and hopping processes exhibit increasing conductance with increasing temperature. However, it has recently been proposed that tunneling can also yield temperature-dependent transport due to the thermal broadening of the Fermi energy of the contacts. In this work, we examine a series of rigid, planar furan oligomers that are free from a rotational internal degree of freedom to examine the temperature dependence of tunneling transport directly over a wide temperature range (78-300 K). Our results demonstrate conductance transition from a temperature-independent regime to a temperature-dependent regime. By examining various hopping and tunneling models and the correlation between the temperature dependence of conductance and molecular orbital energy offset from the Fermi level, we conclude thermally assisted tunneling is the dominant cause for the onset of temperature-dependent conductance in these systems.

The lotus leaf surface is modified by covering nanofibers to check its wetting property. The well-known lotus effect of the modified surface is greatly weakened, and a hydrophilic property is found. The geometric potential theory is used to ex-plain the phenomenon, it shows that the two adjacent nanofibers can produce a high geometric potential to push water molecules to move along the fibers, as a result, a hydrophilic surface is predicted after surface modification. An experiment is designed to elucidate the main factors affecting the wetting property of the modified surface of lotus leaf.

Two thin-film 2D organic-inorganic hybrid perovskites, i.e., 2-phenylethylammonium lead iodide (PEPI) and 4-phenyl-1-butylammonium lead iodide (PBPI) were synthesized and investigated by steady-state absorption, temperature-dependent photoluminescence, and temperature-dependent ultrafast transient absorption spectroscopy. PBPI has a longer organic chain (via introducing extra ethyl groups) than PEPI, thus its inorganic skeleton can be distorted, bringing on structural disorder. The comparative analyses of spectral profiles and temporal dynamics revealed that the greater structural disorder in PBPI results in more defect states serving as trap states to promote exciton dynamics. In addition, the fine-structuring of excitonic resonances was unveiled by temperature-dependent ultrafast spectroscopy, suggesting its correlation with inorganic skeleton rather than organic chain. Moreover, the photoexcited coherent phonons were observed in both PEPI and PBPI, pointing to a subtle impact of structural disorder on the low-frequency Raman-active vibrations of inorganic skeleton. This work provides valuable insights into the optical properties, excitonic behaviors and dynamics, as well as coherent phonon effects in 2D hybrid perovskites.

Traditional silicon-based photodetectors are limited by the band gap of silicon, which results in a limited working wavelength range. In this report, due to the excellent properties of Indium Antimonide, the InSb/Si heterojunction photodetectors are fabricated. Under ambient temperature of 280K, as-prepared photodetectors show a specific detectivity of 9.31011 cm Hz1/2/W, responsivity of 54 mA/W, on/off ratio of 5104 under the laser irradiation of 635 nm. In order to explore the influence of working temperature on device performance, the photoresponse at different temperatures was tested. This report proved that as the working temperature increases, the responsivity and specific detectivity of the device decrease, and the performance of the device becomes worse.

ZnO:S quantum dots (QDs) were synthesized by a microwave hydrothermal method. The effects of L-cysteine (L-cys) on the crystal structure, size, morphology, band gap energy and photoluminescence (PL) properties were studied by XRD, EDS, TEM, FTIR, DRS and PL spectroscopy, respectively. The XRD results showed that all samples had a wurtzite structure ZnO crystal structure and the average crystallite size was 8.4, 5.8, and 9.2 nm for ZnO, ZnO:S and L-cys capped ZnO:S (LZOS) QDs, respectively. The EDS, HRTEM and FTIR results confirmed L-cys was capped on the surface of ZnO:S QDs. It was found that the band gap energy was 3.25, 3.29 and 3.31 eV for ZnO, ZnO:S and LZOS QDs, successively. PL spectrum of ZnO QDs showed two emission peaks in the UV and visible region, respectively. When doping S into ZnO, the intensity of the UV emission reduced, while the intensity of the visible emission dramatically increased. Also, L-cys coated obviously enhanced the PL intensity of ZnO:S QDs. This work suggested that LZOS QDs could be applied in luminescent devices.

Background: The patented bubble electrospinning, which is a simple and effective technique for mass-production of polymer nanofibers, has been studying extensively, but it is still under development. In the bubble electrospinning, multiple jets move from the positive electrode to the receptor, a long distance between the two electrodes is needed to guarantee complete solvent evaporation, as a result a relative high voltage is needed. Objective: The aim of the present study is to use an auxiliary electrode and an auxiliary air flow to improve bubble electrospinning with lower voltage and higher output than those by its traditional one. Methods: The modification of the bubble electrospinning with an auxiliary electrode and an auxiliary airflow is used to fabricate nanofibers. The auxiliary electrode is close to the positive electrode. The experiment was carried out at room temperature with 8%PVA solution. The result was analyzed with a S4800 cold field scanning electron microscope (SEM, Hitachi S-4800, Tokyo, Japan). Results: The auxiliary electrode can generate a strong induced electric field force. With the action of airflow, the jets will fly to the receptor instead of the auxiliary electrode. Conclusion: Both auxiliary electrode and auxiliary airflow are two important factors affecting the spinning process. It can reduce the spinning voltage and improve spinning efficiency.

Cigarette smoke will cause irreversible damage to human health and living environment. It is especially important to accurately detect and effectively prevent cigarette smoke. This paper fabricates a fiber membrane filmed with carbon nanopowders as a smoke sensor. The experiment reveals that the fabricated membrane is sensitive to the smoke, two laws are proposed to model the current change of the sensor. Fractal calculus is used to exactly predict the current property at the initial stage, and a fractal modification of the current law is proposed. The present technology provides an economic way to mass-production of smoke sensors.

Carbon materials are promising candidates for sensors to detect heavy metal ions. This paper reported an effective method of fabricating nanofiber membrane sensor for detection of heavy metal ions by electrospinning with the carbon nanoparticles and PANi (polyaniline) as additives. The results revealed that the PANi/C/PAN nanofiber membrane was the most economical approach to adsorbing and detecting metal ions with highly sensitive property. This paper sheds a light on an economic fabrication of nanofiber membrane sensor with well-defined characteristics in electrical sensors and adsorption applications.

A kind of gas nitriding method catalyzed by rare earth for 40CrNiMoA alloy steel was researched in this article. Effect of temperature on surface hardness of gas nitriding method catalyzed by rare earth, change law of layer depth with time at 500 °C were carried out and compared with normal gas nitriding. Based on these researches, gas nitriding method catalyzed by rare earth was optimized. The results show that gas nitriding catalyzed by rare earth can not only increase the nitriding speed, but also enhance the surface hardness of the nitriding layer. Using three - stage gas nitriding method catalyzed by rare earth and after 40 hours, the samples can meet the need of nitrided layer depth no less than 0.5mm, surface vickers hardness no less than 600.

An electrospinning process is to produce nanofibers from a polymer solution by a high electrostatic force, which is used to eject jets from a Taylor cone formed on a nozzle. When a moving jet approaches to a receptor within few nanometers during the electrospinning process, a Casimir-like attraction is formed, which attracts the jet’s end to the surface of the receptor. Thousands of thousands nanofibers will be attached on the receptor’s surface or attached on each other, as a result a nanofiber membrane is formed. The geometric potential was implemented to explain the nanoscale adhesion, which is greatly affected by the attachment oscillation. Mathematical models are established to describe the attachment oscillation under the Lennard-Jones potential and the geometric potential, respectively, and their amplitude-frequency relationship is elucidated analytically. The present theory gives an alternative explanation of the gecko effect and molecule scale forces. Keywords: Lennard-Jones potential, Van der Waals force, Casimir force, Geometrical potential, Molecule oscillation, Smart adhesion, Parthenocissus tricuspidata, Gecko effect, Macromolecular electrospinning

Rocks have good chemical and thermal properties, which are widely distributed in mountainous areas and contain a great number of chemical elements. Weathered rock powders were used as an additive in an electrospun solution to fabricate rock powder-based nanofibers, and the morphology and thermal property of nanofibers were studied. The results revealed that the rock powder was the most economical approach to fabrication of nanofibers with excellent thermal property and high hydrophilicity. This paper sheds a light on rock powder-based nano-fibers with well-defined characteristics for advanced applications for high temperature filtration and absorption, fire prevention and others.

The complex refractive index of reduced graphene oxide and CuFe2O4 composites prepared by hydrothermal method was calculated using infrared Micro-reflective spectra and K-K relation, and the calculation errors were analyzed according to its IR transmission and spectral reflectivity calculated by Fresnel formula. And then normal emissivity of the composite in IR atmospheric window was calculated by means of Fresnel formula and modified refraction angle formula. The calculation accuracy was verified by comparing measured normal total emissivity with the calculated one. The results show that complex refractive index and normal emissivity calculated by the formulas have a high accuracy. It has been found that the composite has a good absorption and radiation characteristics in IR atmospheric window and a strong scattering ability in middle IR region by analyzing its extinction, absorption and radiation properties in IR region. Therefore, it may be used as IR absorption, extinction and radiation materials in some special fields.

Many nature materials have hierarchical structure, and its last cascade is always on a molecule scale, e. g., double-stranded DNA, making the hierarchy effective with minimal building blocks. Now artificial hierarchy can begin with a nanoscale level to embody the material with remarkable and fascinating properties which can be never achieved using non-hierarchical structure. A strong desire to fabricate some biomimicking hierarchies from a molecule level has been stimulating scientists. Herein we show that molecular structure can be easily controlled by a long and narrow tube, and self-assembly of macromolecules can be achieved to improve its crystallinity with plenty of excellent properties. We anticipate this paper to be a starting point for more sophisticated fabrication of fibers with self-assembly of macromolecules.

A fast and accurate estimation of the arsenic concentration in an electrochemical sensor is of great importance in optimization of the sensor. Legendre wavelet method was used for this purpose (Electrochimica Acta, 266(2018), 27–33), however, after a careful looking through the solution process, the model can only lead to a zero solution, this paradox can be successfully solved by a fractal modification of the surface coverage model. A simple solution process to the fractal model is elucidated.

Understanding the reaction mechanism of phenol ozonation in coking wastewater is very important for industrial applications of the ozonation process. Ozonation of p-nitrophenol in water at 300 K was simulated by ReaxFF force field molecular dynamics (ReaxFF MD) employing the GPU-enabled high-performance code of GMD-Reax and a unique code of VARxMD developed in authors' group. Evolution trends of aromatic ring opening, CO2 generation, dominant radicals (center dot OH, center dot O2, center dot O), and H2O clusters were obtained. The simulated CO2 generation and reduction of aromatic ring could be described with pseudo-first-order kinetics. Moreover, the reaction pathways for the ozonation of p-nitrophenol can be divided into three stages: hydrogen abstraction, opening of the six-membered-ring structure, and the breaking of C-C bonds. The simulations revealed the important role of radicals and water clusters in the ozonation of p-nitrophenol. This work is an attempt to investigate the ozonation mechanism of phenols in aqueous solutions at room temperature using ReaxFF MD, which should be helpful for further experimental or theoretical investigation of the mechanism.

Graphite intercalation compounds (GIC) are the most common precursors for expanded graphites which are promising materials for many applications. A series of GICs with different expanding volumes (EV) were prepared by a two-step chemical intercalation way. Effects of the input of oxidant and intercalating agent on the EV of GICs were discussed. The microstructures and morphologies of graphites before and after intercalation were analylized by X-ray diffraction and scanning electron microscope, respectively. The results show that the GIC with an EV of 600 ml⋅g-1 may be prepared under temperal conditions by a two-step intercalation way. The interlayer spacing of the pre-GIC formeded by one-step intercalation is a bit larger than that of natural graphites, while the interlayer spacing of the GIC obtained by two-step intercalation becomes much larger than that of the pre-GIC because of secondery intercalation. When the d-spacing (d002) value of the GIC rises from 0.3590 nm up to 0.3711nm, its EV increases from 267 up to 600 ml⋅g-1 due to the decomposition and release of much more intercalated substances during a thermal shock.

Based on the interaction mode of capture probe-target-signaling probe (CP-T-SP), an electrochemical DNA sensor based on the synergism strategy of Au electrode with large surface area, background suppression and multi-redox-modified signaling probe is developed for the detection of a specific DNA sequence. The proposed sensor can detect as low as ∼2 fM target DNA with good mismatch discrimination ability and outstanding working capability in real complex matrixes.

The breakage and particle size redistributions in an ultrasound-intensified leaching process were explored experimentally and analyzed statistically. It was found that particle size distributions (PSDs) of this atomic crystal silica may be changed to a certain extent by ultrasound, but the width of PSD cannot be altered under the conditions considered. Chemical reactions played an important reciprocal causality to the breakage and the particle size redistributions, and the contribution was about a half on the mean particle size. The most severe breakup happened at the maximum volume percentage of PSD rather than in the region of the largest particle size end. The ability of conventional stirring to break the silica particles may be larger as expected when the same power was used. The morphology of the silica particles verified that the change before and after leaching is small.

ZnS:O2− (ZSO) nanoparticles were synthesized using a low temperature solid-state reaction method. The effects of annealing conditions and the content of the surfactant polyethylene glycol (PEG) on photoluminescence (PL) properties of the ZSO nanoparticles were studied. It was found that annealing and adding PEG during the synthesis did not change the crystal structure of ZSO nanoparticles, and their average crystallite size increased with increasing annealing time and temperature, but decreased with increasing PEG content. The emission intensity of ZSO nanoparticles was found to be enhanced after annealing or using PEG during the synthesis. Optimal annealing conditions both in air and vacuum and the optimal content of PEG were obtained for achieving maximum emission intensity from the ZSO nanoparticles.

To establish a finite element (FE) model of the pig head for simulating firearm wounds. An experimental study was carried out by measuring impact load parameters from 17 fresh pig heads that were shot at the right part of cranium by a standard 7.62 mm M43 bullet. FE analysis was executed through the LS-DYNA code under impact loads similar to those obtained from the experimental study. The residual velocity, the transferred energy from the bullet to the cranium, and the surface area of the entrance showed no statistical differences between the FE simulation and the experimental study. However, the mean surface area of the exit wounds was significantly larger than that of the entrance wounds in the experimental and FE study. Although the results of FE analysis corresponded with the experiment study, FE analysis further revealed that the stress zones were mainly located at the impact region of the cranium, mainly located in occipital lobe, frontal lobe and skull base of brain, with a lower speed of stress distribution. The FE model was appropriate and conformed to the basic principles of wound ballistics.

New supramolecular structures were designed in this work using large-sized polyoxometalates (POMs) and crown-ether-based supramolecular cations selected as building blocks. Two novel supramolecular inorganic–organic hybrids [(3-F-4-MeAnis)([18]crown-6)]2[SMo12O40]•CH3CN (1) and [(4-IAnis)([18]crown-6)]3[PMo12O40]•4CH3CN (2) (3-F-4-MeAnis = 3-fluoro-4-methylanilinium and 4-IAnis = 4-iodoanilinium) were synthesized. Crystals 1 and 2 have been characterized by infrared spectroscopy (IR) and elemental analysis (EA). Based on X-ray diffraction analysis, Crystals 1 and 2 were constructed through noncovalent bonding interactions and belong to different space groups due to the difference of the building blocks used. Supramolecular cations formed due to strong N–H···O hydrogen bonding interactions between the six oxygen atoms of [18]crown-6 molecules and nitrogen atoms of anilinium derivatives. Crystal 1 has two different supramolecular cations with an anti-paralleled arrangement that forms a dimer through weak hydrogen bonding interactions between adjacent [18]crown-6 molecules. Crystal 2 has three independent supramolecular cations that fill large spaces between the [PMo12O40] polyoxoanions forming a rhombus-shape packing arrangement in the ac plane. Crystals 1 and 2 are unstable at room temperature.

ZnS:X− (X = F and I) nanoparticles have been prepared successfully via a solid-state method at low temperature, and the effects of doping with X− on the photoluminescence (PL) properties of ZnS nanoparticles have been investigated. X-ray powder diffraction (XRD), energy-dispersive X-ray spectrum (EDS), transmission electron microscope (TEM), ultraviolet–visible diffusion reflection spectra, and emission and excitation spectra were used to characterize the crystal structure, chemical compositions, diameter, surface states, and optical properties of ZnS:X− (X = F and I) nanoparticles. XRD studies showed the phase singularity of ZnS:X− particles having zinc-blende (cubic) structure with an average crystallite size 4.7–11.0 nm. The results indicated that the PL of doping halogen ZnS nanoparticles can be enhanced remarkably by controlling suitable halogen doping, and the most intense emission was obtained when X/Zn = 0.3 and 0.45 under 387 nm excitation corresponding to X = F and I, respectively. The emission intensity of ZnS:F− (F/Zn = 0.3) nanoparticles was higher than that of ZnS:I− (I/Zn = 0.45), and exhibited strong emission with an intensity about 9 times higher than the undoped nanoparticles. It was found that the PL of ZnS nanoparticles doped with various halogens was decreased with the increase of the halogen ion radius.

The microscopic deformation mechanism was taken into account to research the high efficient solid ice and snow clearing technology. The solid ice and snow constitutive model was established, which the deformation mechanism of snow microstructure and macroscopic continuous behavior were linked together, considering the damage of solid ice and snow depends on the mechanical properties of the snow volume elements of the grain bonds between grains, and using the microstructure factor scale the stress state of microstructure in the continuous stress. The density is 520Kg/m3-600Kg/m3 of the solid ice and snow was selected for studying and the homogeneous triaxial loading test was conducted by using the SJ-1A strain control type triaxial shear instrument. The relations of local strain rate with limit stress was established according to the simulation analysis conducted the constitutive model that was been established, the results found that both of those showed a near-linear relations, it was fit with the experience relations. The computer simulation and experimental curves deviated a little, and the reasonableness of the established solid ice and snow constitutive model was verified. Studied have shown that the failure rule of solid ice and snow can be well described by the constitutive model, which presents a theoretical reference for the design of key icebreaking components.

An improved simple equation to calculate the minority-carrier effective lifetime in photoconductance measurements is proposed by the perturbation method. When the given constraints are satisfied, the given formulation leads to a fast and accurate determination of effective lifetime from the bulk lifetime, surface recombination velocity, the thickness of the wafer, and diffusion coefficient. Keywords: Photoconductance, Lifetime, Recombination, Perturbation method

The electrically controlled birefringence of nematic liquid crystal BL-009 was measured by polarized interference method. The influence of LC absorption effect, the birefringence variation, is discussed in this paper. The experiments results showed the influence to birefringence is big in infrared region. Not only the birefringence value is greatly different with that of unconsidering absorption effect, but also the gradient changing of birefringence curves is obvious. Furthermore, the electrically controlled birefringences of two conditions are compared when the absorption coefficients of ordinary light and the extraordinary light are nearly same and greatly different. The analysis demonstrated the approximate method of absorption coefficient is feasible.

The traction characteristics of lubricant is one of the important parameters of the dynamic performance of bearings design .This paper chose three significant factors affecting the traction coefficient：temperature、load and rotate speed. Test results showed that the traction coefficient under the high load is significantly higher than under low load from room temperature to 135 °C. After more than 135 °C, the traction coefficient under the low load is higher than under the high load. It illustrated that the grease was sensitive to temperature but it reflected high temperature stable performance.The optimum conditions were obtained by Design-Expert software optimization : temperature for 235°C、load for 2800.00N、rotate speed for 183.17r/min and in this time the traction coefficient is at 0.547 in this test. It shown that the grease fitted the low speed and heavy load equipment.

Exfoliated graphite with large expanding volume (EV) was prepared by two-step intercalation, in which the mixture of nitric acid and phosphoric acid, and that of nitric acid and acetic acid were employed as intercalating agent step by step, and potassium permanganate was used as oxidant. Its preparation conditions were optimized by orthogonal experiment and parallel experiment, and its microstructure was analyzed by scanning electron microscope. The results show that the optimal preparation conditions for the first step intercalation are as follows: the mass-volume ratio of natural graphite (NG) to mixed acid is 1: 4, the volume ratio of nitric acid to phosphoric acid is 1: 2, the mass ratio of NG to potassium permanganate is 1: 0.2, and the reaction temperature is 20~30°C for 40~60 minutes. Those for the second step intercalation are as follows: the mass-volume ratio of acidized graphite (AG) to acetic acid is 1: 5, the mass-volume ratio of AG to nitric acid is 1: 1.5, the mass ratio of AG to potassium permanganate is 1: 0.15, and the reaction temperature is 20~30°C for 40~60 minutes, the EV is 450ml/g under the conditions listed above. The interlayers of graphite are fully opened and become a worm-like fluffy rope.

4 groupsconcrete columns specimens which have different eccentricityities were fabricated , The first specimen was just made of reinforced concrete. The second was enlaced with 3 lays carbon fiber reinforced polymer. The third had SFRCs added to it. The last was reinforced with SFRCs and enlaced with carbon fiber reinforced polymer.The results showed that the introduction of fibres as well as wrapping the specimens with FRP improve the strength of concrete,especially its ductility.

ZnS:Cl − nanoparticles with strong blue emission have been synthesized successfully by a solid-state reaction at low temperature. The dependence of photoluminescence (PL) properties of ZnS:Cl − nanoparticles on the Cl − contents was researched, and the influences of the annealing ambience and using polyvinyl alcohol (PVA) during the synthesis on the PL of ZnS:Cl − (Cl/Zn = 0.35) nanoparticles were discussed. X-ray power diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy were used to characterize their structure, chemical state, diameter, surface states, and PL properties. The results showed that ZnS:Cl − nanoparticles had a cubic blende crystal structure and an average crystallite size of 17.40–19.16 nm. The most intensity blue emission peaking at about 425 nm was obtained when Cl/Zn = 0.35 under 330 nm excitation at room temperature. The emission intensity of ZnS:Cl − (Cl/Zn = 0.35) was increased 3-fold than that of ZnS. The results showed that the PL of ZnS:Cl − (Cl/Zn = 0.35) nanoparticles was enhanced after annealing or using PVA during the synthesis, and annealing in vacuum had a stronger effect in improving the luminescence properties of ZnS nanoparticles than in air. This work suggests that it is an effective method to improve the PL intensity of ZnS nanocrystals by doping with Cl − in ZnS.

Cl − -doped ZnS (ZnS:Cl − ) nanoparticles with strong blue emission were synthesized using a facile low temperature solid state reaction method. X-ray powder diffraction, scanning electron microscopy, UV–vis absorption, and X-ray photoelectron spectroscopy were used to characterize their crystal structures, microstructural characteristics, and chemical compositions, respectively. The ZnS:Cl − nanoparticles were quasi-spherical in shape and had a cubic zincblende crystal structure. Cl − doping was found to lead to a reduction in the crystallite size of the ZnS:Cl − nanoparticles. It showed that Cl − doping remarkably enhanced the luminescence properties of the ZnS:Cl − nanoparticles, and an optimal Cl − doping condition was determined. Post annealing was found to further improve the luminescence properties of the ZnS:Cl − nanoparticles. The effect of post annealing temperature on the luminescence properties of the ZnS:Cl − nanoparticles was systematically studied and discussed.

The pressure responding theoretical models are got for two intrinsic Fabry-Perot interferometric fiber pressure sensors fabricated by single mode and multimode fibers with different diameters. The pressure response curves are simulated by Matlab programs. The analysis showed that the sensitivity changing situation is different for two structures. The big size structure has a critical point of sensitivity. Higher sensitivity can be got by two structures, but the small size structure is more attractive than the big size structure.

The theoretical model is got for a new intrinsic Fabry-Perot interferometric fiber pressure sensor structure fabricated by single mode and multimode fibers with different diameters. The pressure response curves are simulated by Matlab software. The analysis results showed that the pressure sensitivity decreased with the diameter of multimode fiber increased at some area, but the sensitivity begins to increase when the diameter value is more than critical point. The high sensitivity can be still got by increasing fiber diameter.

O2−-doped ZnS(ZnS:O) nanoparticles with strong blue emission were successfully synthesized using a facile low temperature solid state reaction method. X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize their crystal structures, sizes, morphologies, and photoluminescence. The ZnS:O nanoparticles were quasi-spherical particles with a cubic zincblende crystal structure, and their average crystallite diameter was about 8.35–13.50 nm. Dependence of the photoluminescence properties of the ZnS:O nanoparticles on the Zn/O ratio in the source materials was studied, and an optimal O2− doping condition was found to be Zn/O=10:5.3. The ZnS:O (Zn/O=10:5.3) nanoparticles exhibited strong blue emission with an intensity 9 times higher than the undoped nanoparticles.

Two kinds of exfoliated graphite have been prepared from graphite flake and graphite powder, and their preparation conditions were respectively optimized by orthogonal experiments and parallel experiments. The effect of graphite size on the characteristics of exfoliated graphite was researched. The microstructure of two kinds of exfoliated graphite was measured by SEM. The results show that the optimal preparation conditions for exfoliated graphite flake are as following: the mass-volume ratio of graphite to mixed acid is 1: 4, the volume ratio of nitric acid to phosphoric acid is 1: 2, the mass ratio of graphite to potassium permanganate is 1: 0.1, and the reaction temperature is 25°C. For exfoliated graphite powder, the optimal mass ratio of graphite powder to potassium permanganate is 1: 0.22, and the consumption of oxidant for exfoliated graphite powder is more than that for exfoliated graphite flake. The longitudinal expansion of graphite flake is more apparent than that of graphite powder and leads to a worm-like fluffy rope.

Exhaust system is the most important infrared radiation source of a long-endurance UAV and the shape of the nozzle contribute to the infrared radiation characteristics of exhaust system. This paper built a 2-D nozzle and use ANSYS14.5 simulated the temperature filed of the plume. And then, spectral infrared radiation characteristics of the plume were obtained by the single band C-G approximation method. Finally, the infrared radiation intensity distribution of the exhaust system of the 2-D nozzle in different planes is obtained. The results show: The infrared radiation of the plume in wide side detection surface is far greater than the narrow side; The infrared radiation of the nozzle in wide side detection surface is smaller than the narrow side; The infrared radiation of the exhaust system in wide side detection surface is smaller than the narrow side. The results maybe contribute to the further study of the infrared radiation characteristics of the long-endurance UAV.

Thermo-mechanical experiments were carried out to study the effect of deformation speed and temperature on the behaviour of a non-quenched and tempered steel during hot forging. And an effective method for correction of friction was used to amend the tested flow stress, Meanwhile, the constitutive equations of flow stress-strain for TL1438 steel during hot forming was established based on the amended flow stress and hyperbolic sine which includes Zener-Hollomon parameter, and related parameters of TL1438 during hot forming was obtained by analyzing the data.

The orientation of the hydrocarbon chains and functionally important chromophore of copper (II) phthalocyanine (CuPc) derivatives are discussed by spectrum assessment methods in ordered thin films. The attention is focused upon the monolayer and multilayer films of CuPc derivatives that are symmetrically and asymmetrically substituted CuPc biosimulation systems. On the basis of infrared (IR) transmission, polarized IR, reflection–absorption (RA) IR spectroscopy and surface enhancement resonance Raman spectra (SERRS) study, following conclusions are given. The hydrocarbon chains of CuPc in the film are in hexagonal or pseudohexagonal subcell packing, and the CH2 asymmetric vibrational vector is oriented with respect to the substrate surface. The macrocycle of CuPc on the Ag substrate is oriented parallel to the surface, and the RA spectroscopy can distinguish the two CH2 stretching modes of benzene cycle. All these studies and results are useful to provide an insight into the nanostructure of the thin films of other kinds of compounds.

In this work, we investigated the influence of annealing on the crystallinity, microstructures, and photoluminescence (PL) properties of ZnO nanoparticles prepared by sol–gel method. The annealing was carried out both in air and vacuum. X-ray powder diffraction, scanning electron microscopy, and ultraviolet–visible spectroscopy were used to characterize the crystal structures, diameter, surface morphology, and PL properties of ZnO nanoparticles. It has been found that both the as-grown and annealed ZnO nanoparticles had a hexagonal wurtzite crystal structure, and their average diameter and crystallinity increased with the anneal time and temperature. Pure blue-emitting behavior was observed in all samples. The emission intensity of ZnO nanoparticles was found to be enhanced after annealing, but it was highly dependent on the annealing conditions. Optimal annealing conditions both in air and vacuum were obtained for achieving maximum emission intensity in the ZnO nanoparticles. The dependence of PL properties of the ZnO nanoparticles on the annealing conditions was discussed.

In this work, molecular crowding agent was first applied to the preparation of molecularly imprinted polymer (MIP)-based drug release system. With S-naproxen as template, the MIPs were prepared with methacrylic acid and ethylene glycol dimethacrylate, in the presence of polystyrene as molecular crowding by precipitation polymerization. Morphology and particle size of the resulting MIP sub-micrometer microparticles were determined by scanning electron microcopy and dynamic light scattering. The influence of several parameters on the sustained release of the imprinted polymers was investigated, including the molar ratio of the imprint molecule to the functional monomers, the molar ratio of the functional monomers to the crosslinking monomers, and the type of the porogen. In addition, the release of the MIP was compared to that of the traditionally prepared imprinted polymers with other porogens. The transport mechanism of template was studied by fitting experiment data with different model equations and calculating the corresponding parameters. The novel MIPs prepared with molecular crowding were able to prolong S-naproxen, in a phosphate buffers solution of pH 7.4, for more than 12 h, indicating better sustained release effect than that prepared with noncrowding agent. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

A QI-free coal tar pitch prepared by solvent extraction from a soft coal tar pitch was subjected to a series of thermal treatments at a predetermined temperature for different holding times. The development of mesophase was discussed in terms of its size and content in the heat-treated pitches. Results showed that the size and yield of the dispersed mesophase spheres in the isotropic matrix strongly depended on the holding temperatures. When the holding temperature was less than 400 °C, only a few of small spheres formed in the mesophase pitches. However, when the holding temperature was over 420 °C, the diameter and yield of mesophase spheres in the heat-treatment pitches increased progressively with increase of the holding time. Treatment at 440 °C for 4h led to 19.9 % of the yield and the average sphere radius was 4.5-100 . In the SEM photograph of mesocarbon microbeads obtained from the heat-treated pitches using soxhlet extraction. Many small flaky particles and sporadic rugby ball-shaped particles were observed as well as a large number of spherical particles.

Zn 1− x Mg x S (0 ≤ x ≤ 0.55) quantum dots (QDs) were successfully synthesized by precipitation method. The crystal structures, microstructures, and optical properties of the Zn 1− x Mg x S QDs were investigated using X-ray diffraction, scanning electron microscopy, and ultraviolet-visible and photoluminescence (PL) spectroscopy. The Zn 1− x Mg x S QDs were found to have a cubic crystal structure and an average crystallite size of 6.40–7.96 nm. It has been shown that an increase in doping Mg 2+ concentration in Zn 1− x Mg x S QDs led to a gradual widening of the band gap and a weakening in the PL intensity of the Zn 1− x Mg x S QDs.

12 RC columns specimens are divided 4 groups which have different eccentricities. Each group has 4 specimens, The first specimen was just made of reinforced concrete. The second was wrapped with 3 lays CFRP. The third had steel fibres added to it. The last was reinforced with steel fibres and wrapped with CFRP.The results showed that the introduction of fibres as well as wrapping the specimens with FRP improve the strength of concrete,especially its ductility.

In order to change surface morphology and contact angle of part, abrasive jet method is discussed in the paper. Glass, steel and titanium are used to study its surface morphology by the processing of abrasive to jet the surface. In addition, the extent of its impact of processing method is studied with different abrasive size. Experiment method and environment are also introduced, and experiment shows that contact angle of glass changes from 14.9° to 93.8° (Titanium and steel also have different degrees of diversification). According to experiment of the method, abrasive jet methods affects contact angle, and it has the value of further research.

ZnO quantum dots (QDs) with strong blue emission have been successfully synthesized by sol–gel method, and their crystal structures, sizes, and photoluminescence properties were characterized by X-ray diffractometer, scanning electron microscope, and ultraviolet–visible spectroscopy. It has been found that ZnO QDs had a hexagonal wurtzite crystal structure, and their average diameter was about 16.0–32.2 nm. Both the reaction time and temperature were found to have a strong influence on the average size and photoluminescence properties of ZnO QDs. Longer reaction time and higher reaction temperature resulted in larger average size for ZnO QDs. It has been shown that at reaction temperature 60 °C the emission intensity for ZnO QDs increased first with reaction time before 7 h and then decreased after 7 h. For the same reaction time 7 h, ZnO QDs synthesized at 60 °C showed the strongest emission intensity. It was found that annealing in nitrogen, vacuum, and air all resulted in an increase of the size of ZnO QDs and a reduction in their photoluminescence. The dependence of the size and properties of ZnO QDs on the reaction parameters as well as the annealing conditions has been discussed.

Carbon fiber reinforced polymer (CFRP) composites have been used extensively because of their excellent performance, but they are susceptible to the impact damages, such as the impact of birds, runway stones and tools off can cause the failure of CFRP composites. Therefore, nondestructive testing of CFRP composites is necessary to promote the failure control and prevention. Ultrasonic burst phase thermography (UBP) developed a few years ago is a defect-selective and fast imaging tool for damage detection. This paper describes the principle of UBP, gives some UBP testing results of impact damages in five CFRP laminated boards. The shape and position of the damages are shown in the phase images visualized and the relationship between the damage areas and impact energy is discussed. The flash pulse thermography (PT) results and ultrasonic C-scan results are also shown as comparison. It is concluded that all of the three NDT methods have their own characteristics and the comparison verifies the feasibility of CFRP impact damage detection using ultrasonic burst phase thermography.

Infrared thermal wave testing is a non-contact inspection technique that maps the surface temperature of an object after some energy is applied to it. The mechanism of pulsed infrared thermal wave testing was analyzed in detail. Glass fiber reinforced composite was tested by infrared thermal wave testing. Some intensive research on quantitative defect evaluation was developed. Through analysis of the temperature-time curve of two points over a suspected defective location and over a sound area on material surface, the change rule of temperature difference was found. It provided a basis for depth quantitative evaluation. According to the peculiarity of infrared image, an image enhancement approach based on mathematical morphology was adopted, which solve the problem of poor contrast and low signal-to-noise ratio caused by pulse heating. And an image processing program was developed to extract the size information of defects.

Electrospinning is always used to fabricate one-dimensional nanofibers. Cylindrical fibers are formed during the spinning process due to the minimal-surface principle. However, when the moving jet has high rigidity, which can counteract the surface tension for a minimal surface, beltlike fibers can be obtained. Using the Hall&ndash, Petch effect, the rigidity of the moving jet can be greatly enhanced by adding nanoparticles. Polyethylene glycol with a nanometric crystallite size of 4 nm and ZrO2 nanoparticles are used as additives in the experiment, a theoretical analysis is carried out, and the theoretical predictions are verified experimentally.

The magnetic force microscopy and a sample vibrating magnetometer have been used to investigate the domain structure in two antiferromagnetically coupled Co/Pt multilayers. In the antiferromagnetic coupled [Pt(0.5 nm)/Co(0.4 nm)] n /NiO(1.1 nm)/[Co(0.4 nm)/Pt(0.5 nm)] n multilayers with perpendicular anisotropy, the antiferromagnetic interlayer coupling strength increases linearly with the repetition number n in Co/Pt multilayers. In demagnetized states, relatively shifted domain walls in the two Co/Pt multilayers are observed, with net ferromagnetic stripes formed between them for the repetition number n less than 5, and the stripe width decreases with the increase of n. The occurrence of these features can be attributed to the competition between the interlayer coupling and magnetostatic energies.

Si 4+ and B 3+ were doped into the spinel block of blue-emitting BaMgAl 10 O 17 :Eu 2+ phosphor. Their photoluminescence, such as emission characteristic and thermal stability, were investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation. The results showed that proper quantities of Si 4+ or B 3+ doping could obviously improve the emission intensity. However, the thermal stability of Si 4+ or B 3+ doped phosphors was worse than that of undoped samples. Based on lattice defect theory, the mechanisms of these interesting phenomena were discussed and explained, which revealed that the thermal degradation of BaMgAl 10 O 17 :Eu 2+ had great correlation with the lattice environment.