不同形貌碳酸钙的制备及其对PVC薄膜力学性能的影响

选用偏钒酸铵、聚乙二醇、十六烷基三甲基溴化铵、焦磷酸钠十水和聚乙烯吡咯烷酮作为碳酸钙形貌控制剂，以氯化钙和碳酸钠为原料，用氯化法制备得到了片状、菱形、棒状、球状和立方体状5种不同形貌碳酸钙微粒，并研究不同形貌碳酸钙颗粒形态对软质聚氯乙烯（PVC）薄膜力学性能的影响。结果表明，不同形貌碳酸钙均提高了PVC薄膜的力学性能，PVC薄膜拉伸强度和断裂伸长率均提高显著；其中，棒状形貌碳酸钙对PVC薄膜力学性能的提高效果最好，拉伸强度达到了27.11 MPa；菱形碳酸钙改性PVC薄膜的断裂伸长率最高，为98.23 %。     

Fast Transmission Photothermal Radiometry via Sampling by an Internal Computer Sound Card

During the last few decades, photothermal radiometry (PTR) has been greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system employs an expensive lock-in amplifier to detect the weak photothermal signal, which leads to high cost and long test time. In this paper, a fast transmission PTR system based on sampling by using an internal computer sound card was developed to lower the system cost and shorter the test time. A piece of amorphous silicon (a:Si) thin film solar cells with artificial defects was prepared and tested by the system. The results show that the sharpened defects can be identified easily and quickly according to the significant peaks of the original infrared signal sampled by the internal computer sound card. Furthermore, more detailed defects can be investigated by processing the infrared signal. These validate the effectiveness of the proposed transmission PTR system as a low cost and efficient non-destructive test technique.     

Cleaning of viscous drops on a flat inclined surface using gravity-driven film flows

We investigate the fluid mechanics of cleaning viscous drops attached to a flat inclined surface using thin gravity-driven film flows. We focus on the case where the drop cannot be detached either partially or completely from the surface by the mechanical forces exerted by the cleaning fluid on the drop surface. Instead a convective mass transfer establishes across the drop–film interface and the fluid in the drop dissolves into the cleaning film flow, which then transports it away. The characteristic time scale of dissolution is much longer than the advection time scale in the film flow. Thus, the shape and size of the drop can be considered as quasi-steady. To assess the impact of the shape and size of the drop on the velocity of the cleaning fluid, we have developed a novel experimental technique based on particle image velocimetry. We show the velocity distribution at the film surface in the situations both where the film is flowing over a smooth surface, and where it is perturbed by a solid obstacle representing a very viscous drop. We find that at intermediate Reynolds numbers the acceleration of the starting film is overestimated by a plane model using the lubrication approximation. In the perturbed case, the streamwise velocity is strongly affected by the presence of the obstacle. The upstream propagation of the disturbance is limited, but the disturbance extends downstream for distances larger than 10 obstacle diameters. Laterally, we observe small disturbances in both the streamwise and lateral velocities, owing to stationary capillary waves. The flow also exhibits a complex three-dimensional converging pattern immediately below the obstacle.     

Annealing temperature dependent structural and optical properties of electrodeposited CdSe thin films

Cadmium selenide films were synthesized using simple electrodeposition method on indium tin oxide coated glass substrates. The synthesized films were post annealed at 200 °C, 300 °C and 400 °C. X-ray diffraction of the films showed the hexagonal structure with crystallite size <3 nm for as deposited films and 3–25 nm for annealed films. The surface morphology of films using field emission scanning electron microscopy showed granular surface. The high resolution transmission electron microscopy of a crystallite of the film revealed lattice fringes which measured lattice spacing of 3.13 Å corresponding to (002) plane, indicating the lattice contraction effect, due to small size of CdSe nanocrystallite. The calculation of optical band gap using UV–visible absorption spectrum showed strong red-shift with increase in crystallite size, indicating to the charge confinement in CdSe nanocrystallite.     

Effect of biodegradable film (lyophilised alga Fucus spiralis and sorbic acid) on quality properties of refrigerated megrim (Lepidorhombus whiffiagonis)

The effect of replacing the on‐board currently employed polyethylene film by a novel type of environmentally friendly packaging was studied. For it, a polylactic acid (PLA) biodegradable film including lyophilised alga Fucus spiralis and sorbic acid was applied during megrim (Lepidorhombus whiffiagonis) refrigeration and its effect on fish quality loss was evaluated. Thus, sensory assessment showed that samples wrapped up with PLA film including 8% alga and 1% sorbic acid were still acceptable on day 11, while control fish specimens (kept under polyethylene film) were rejected at that time. Under such biodegradable film condition, a preservative effect was also implied according to chemical indices assessment related to microbial activity (trimethylamine–N) and lipid oxidation development (peroxide and fluorescent compounds formation); additionally, lower mean numbers for different microbiological groups (aerobes, Enterobacteriaceae and psychrotrophs) were detected. This result provides a promising replacement strategy to enhance refrigerated fish quality and reduce the waste material content.     

Hybrid nanocomposite thin films deposited by emulsion-based resonant infrared matrix-assisted pulsed laser evaporation for photovoltaic applications

Emulsion-based, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) was used to deposit CdSe nanoparticle films and hybrid nanocomposite films comprising colloidal CdSe nanoparticles embedded in a low band gap polymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT). We show that, in contrast to traditional MAPLE deposition, the CdSe nanoparticle film deposited by emulsion based RIR-MAPLE is contiguous and uniform, and it maintains the optical properties of the nanoparticle solution. Moreover, we show that the RIR-MAPLE deposited PCPDTBT/CdSe hybrid nanocomposite film exhibits a relatively random and uniform distribution of CdSe nanoparticles without the significant phase segregation that is observed in hybrid nanocomposite films deposited by spin-casting. Finally, hybrid organic solar cells based on nanocomposite films deposited by the RIR-MAPLE technique were fabricated and characterized, showing 0.4% power conversion efficiency. This is the first demonstration of a polymer–nanoparticle hybrid organic solar cell fabricated by a MAPLE-related technique.     

Influences of Ga concentration on performances of CuInGaSe2 cells fabricated by sputtering-based method with ceramic quaternary target

Copper Indium Gallium Selenide (Cu(In,Ga)Se₂, CIGSe) absorbers with different Ga contents were prepared by sputtering CIGSe ceramic targets and post-annealing. CIGSe solar cell devices were fabricated with other functional layers. The device performances and absorber properties were investigated. Increasing Ga content led to an increase in V_OC and a decrease in J_SC. Ga was supposed to diffuse towards back contact during the annealing process. The best performance was obtained as the ratio of Ga/(In + Ga) reaches 0.32 with the efficiency of 13.8% and a V_OC of 537 mV.     

Dielectric,ferroelectric, and piezoelectric properties of lead-free Ba0.95Ca0.05Ti1-xZrxO3 ceramics

Abstract

Ba_0.95Ca_0.05Ti_1-xZr_xO₃ (BCTZO) ceramics were prepared by a solid state reaction method. The samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and X-ray absorption near edge structure (XANES). The ceramics exhibit a pure perovskite structure. The average grain size gradually decreases with increasing Zr concentration. XANES results indicate that the intensities of pre-edge peaks dropped with increasing Zr concentration. The BCTZO ceramic of x?=?0.05 has the optimum electrical properties with the maximum dielectric constant (ε'_m), remanent polarization (2P_r), coercive electric field (2E_c) and piezoelectric charge constant (d₃₃) of 7,244, 12.54 (μC/cm²), 5.29 (kV/cm) and 288 (pC/N), respectively.     

Inkjet-printed Ag@SDC core-shell nanoparticles as a high-performance cathode for low-temperature solid oxide fuel cells

This work demonstrates the superior thermostability of silver-based nanoparticle cathodes under continuous solid oxide fuel cell operation by coating the samarium-doped ceria (SDC) thin shell over silver nanoparticles. The Ag-core/SDC-shell (Ag@SDC) nanoparticles prepared by solvothermal synthesis (Ag core diameter = 48 nm; average SDC shell thickness = 2–5 nm) is inkjet-printed on electrolyte substrates as a thin film cathode. The Ag@SDC film survives the 48-h thermal annealing and its most porosities remain visibly un-agglomerated. The results of fuel cell current stability test show that the cell using the Ag@SDC nanoparticle cathode have only 3% of current degradation after 25 h, which is remarkably lower than that of the cell using the bare Ag nanoparticle cathode (96.1%). In addition, the electrochemical performance of the bare silver cathode in oxygen reduction reaction has significantly improved because of the enhanced surface oxygen adsorption/dissociation process provided by the SDC thin shell.