Improvement of actuation performance of dielectric elastomers by barium titanate and carbon black fillers

Dielectric elastomers are promising materials for actuators resembling human muscle. Among elastomers, acrylic rubbers (ACM) have shown good actuation performance but its use is limited by the high operating voltages required. The present work demonstrates that simultaneous incorporation of nanostructured carbon black and dielectric fillers offers an increase in a dielectric permittivity and a suitable modulus of the elastomers matrix, enabling an improved electro‐mechanical actuation performance at low voltages. By the use of reinforcing carbon black and barium titanate in an acrylic elastomer matrix a sixfold increase in the dielectric permittivity was realized. A fine tuning of the actuation stress and, consequently, actuation strain can be done by a judicial selection of the different filler concentrations in the soft rubber matrix. Finally, a synergistic effect of the fillers was observed in the improved actuation performance of the developed materials. This work may pave the way to design dielectric elastomers for actuator fabrication. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44116.     

再生纤维的能效筛选

当今的高速印刷机械和造纸机械对纤维质量和浆料的洁净度提出了更严格的要求。借助于优化的筛选工艺可以以高的生产效率和低的能耗达到所要求的浆料质量。     

Liquid-crystalline behaviour of some carboxylic acids

Summary A series of 4--carboxyalkoxyphenyl-4-methoxybenzoates 2 has been prepared. Compounds with a spacer length of n=3 and n=5 show liquid crystalline behaviour. The products were characterized by IR and ¹HNMR-spectroscopy, mass spectrometry, optical microscopy and DSC-measurements. The compounds are potentially useful as side-groups in liquid-crystalline polymers.     

The effect of reaction conditions on the oxidation of veratryl alcohol catalyzed by cobalt salen-complexes

Cobalt salen-type [salen=N,N′-bis(salicylidene)ethylenediamine] complexes 1–6 were studied as catalysts for dioxygen activation in the oxidation of veratryl alcohol in basic aqueous conditions. The complexes Co(salen) (1), Co(CH₃salen) (2) [CH₃salen=N,N′-bis(methylsalicylidene)ethylenediamine], Co(4OHsalen) (3) [4OHsalen=N,N′-bis(4-hydroxosalicylidene)ethylenediamine], Co(sulfosalen) (4) [sulfosalen=N,N′-bis(5-sulfonatosalicylidene)ethylenediamine], Co(acacen) (5) [acacen=N,N′-bis(acetylacetone)ethylenediamine) and Co(N-Me-salpr) (6) [N-Me-salpr=bis(salicylideniminato-3-propyl)methylamine] were chosen to examine the influence of ligand structure on the catalytic activity. The effect of reaction conditions on the oxidation of veratryl alcohol was studied by varying temperature, pH, time or the nature and amount of the axial base needed to enhance the activity of complexes 1–5. The catalytic behaviour of the studied complexes was shown to be very depended on the applied conditions and distinct differences could be observed among the complexes. In all reactions, veratraldehyde was the only product observed. The unsubstituted complex 1 was the most efficient catalyst in the studied system achieving turnover numbers of up to 28 at 80 °C and pH 12.5.     

Formulation,Characterization and Stability Assessment of a Food‐Derived Tripeptide,Leucine‐Lysine‐Proline Loaded Chitosan Nanoparticles

The chicken‐ or fish‐derived tripeptide, leucine‐lysine‐proline (LKP), inhibits the angiotensin converting enzyme and may be used as an alternative treatment for prehypertension. However, it has low permeation across the small intestine. The formulation of LKP into a nanoparticle (NP) has the potential to address this issue. LKP‐loaded NPs were produced using an ionotropic gelation technique, using chitosan (CL113). Following optimization of unloaded NPs, a mixture amount design was constructed using variable concentration of CL113 and tripolyphosphate at a fixed LKP concentration. Resultant particle sizes ranged from 120 to 271 nm, zeta potential values from 29 to 37 mV, and polydispersity values from 0.3 to 0.6. A ratio of 6:1 (CL113:TPP) produced the best encapsulation of approximately 65%. Accelerated studies of the loaded NPs indicated stability under normal storage conditions (room temperature). Cytotoxicity assessment showed no significant loss of cell viability and in vitro release studies indicated an initial burst followed by a slower and sustained release.     

Performance analysis of power generating sludge combustion plant and comparison against other sludge treatment technologies

Expectations on wastewater sludge treatment and recovery of its energy and material contents are increasing because of the tightening legislation and the obligation to reduce environmental impacts of sludge disposal. The objective of this study was to analyze the performance of a heat and power generating sludge combustion plant from technical and economical viewpoints and to compare the studied concept to optional sludge treatment technologies. The plant performance was modeled for sewage sludge produced by approximately 200,000 inhabitants. Two plant sizes below 1000 kWe range were investigated, the smaller plant using sludge as the only fuel and the larger plant with wood chips as the additional fuel. The plants were compared with heat-only plants of similar size. The payback periods for heat-only plants are typically shorter than with the cogenerating plants because the changes in plant investment affect stronger the economy than do the revenues from selling electricity. The gate fee of sludge treatment has the strongest effect on the payback period. The selection of the plant concept (cogeneration, heat only or pure electricity generation) is, however, affected more by the local demand of heat and electricity than pure economy. The selection of the optimal technology for sludge treatment is a complicated task. The studied concept can be the optimal choice, for example, if there is no cement kiln or co-combustion possibility near the source of sludge, if there is no land enhancement demand for the digested sludge, or if the energy surplus from combustion compared to anaerobic digestion is considered more valuable than nutrient recovery possibility from digestion. If the new technology concept is found competitive, it still has to meet the challenge of acceptability from the business, social and cultural points of view.     

Charge transfer resistance of spray deposited and compressed counter electrodes for dye-sensitized nanoparticle solar cells on plastic substrates

Electrochemical impedance spectroscopy was used to determine the effective charge transfer resistances of porous dye-sensitized solar cell counter electrodes prepared by low-temperature spray deposition and compression of conductive carbon and platinized Sb-doped SnO₂ powders on indium tin oxide-coated plastic substrates. The charge transfer resistances were 0.5–2 and 8–13 Ω cm², respectively, when using 3-methoxypropionitrile as the electrolyte solvent. The manufacturing method used lends itself to produce mechanically stable and even-quality electrodes in an easy and fast manner.     

防锈油不同涂油量对冷轧钢板腐蚀行为的影响

采用盐水浸泡实验探讨了0.4,0.9,1.2和1.7 g/m² 4种涂油量对冷轧钢板腐蚀行为的影响。结果表明,在5%NaCl溶液中浸泡4 h时,涂油量为1.7 g/m²的钢板保护效率最高,为52.13%,涂油量为0.4 g/m²的钢板保护效率则最低,只有29.2%;浸泡20 h时,1.2和1.7 g/m²两个涂油量的钢板锈蚀等级能保持B级。EIS和Mott-Schottky数据表明,在同一浸泡时间下,涂油量越大的试样其电荷转移电阻越小,载流子密度越大,耐蚀性更好。