Yongsheng Guo

Effects of dimethyl or diethyl carbonate as an additive on volatility and flash point of an aviation fuel

Vapor pressures and flash points for several mixtures of an aviation fuel with dimethyl carbonate (DMC) or diethyl carbonate (DEC) have been measured, respectively, over the entire composition range. Correlation between the experimental vapor pressures and the equilibrium temperatures by the Antoine equation is performed for each mixture. The bubble-point lines of pressure versus composition at different temperatures and those of temperature versus composition at different pressures are then obtained from the Antoine correlations. It is found that DMC and DEC are the oxygenated hydrocarbon additives that can adjust effectively the volatility and flash point of the aviation fuel. The correlation of the flash points with the vapor pressure data for the pseudo-binary mixtures of the fuel and DMC or DEC gives satisfactory results.

Study on volatility and flash point of the pseudo-binary mixtures of sunflowerseed-based biodiesel + ethanol

Volatility and flash point for the pseudo-binary mixtures of sunflower seed-based biodiesel+ethanol were measured over the entire composition range. The biodiesel was prepared by the transesterification of sunflower seed oil in supercritical methanol without using any catalyst. The vapor pressures of mixtures of biodiesel+ethanol as a function of temperature were measured by comparative ebulliometry with an inclined ebulliometer. The vapor pressures versus composition at different temperatures and temperatures versus composition at different pressures were obtained from Antoine correlations. It is found that ethanol can adjust effectively the volatility and flash point of the biodiesel. The correlation of the flash points with the vapor pressure data for the pseudo-binary mixtures of biodiesel+ethanol displays agreement with the experimental data obtained by closed cup test.

Photoinhibition and xanthophyll cycle activity in bayberry (Myrica rubra) leaves induced by high irradiance

The effect of high irradiance (HI, photosynthetically active photon flux density of 1 300 µmol m−2 s−1) on net photosynthetic rate (PN), chlorophyll fluorescence parameters, and xanthophyll cycle components were studied in fruit tree bayberry leaves. HI induced the photoinhibition and inactivation of photosystem 2 (PS2) reaction centres (RCs), which was characterized by decreased PN, maximum yield of fluorescence after dark adaptation (Fm), photochemical efficiency of PS2 (Fv/Fm) and quantum yield of PS2 (ΦPS2), and increased reduction state of QA (1-qP) and non-photochemical quenching (NPQ). Initial fluorescence (F0) showed a decrease after the first 2 h, and subsequently increased from the third hour exposure to HI. Furthermore, a greater increase in the ratio (Fi-F0)/(Fp-F0) which is an expression of the proportion of the QB non-reducing PS2 centres, whereas a remarked decrease in the slope of Fi to Fp which represents the rate of QA reduction was observed in leaves after HI exposure. Additionally, HI caused an increase in the pool size of the xanthophyll cycle pigments and sustained elevated contents of zeaxanthin (Z), antheraxanthin (A), and de-epoxidation state (DES) at the end of the irradiation period. During HI, decreased Fm, Fv/Fm, ΦPS2, NPQ, slope of Fi to Fp, V+A+Z, and DES, and increased F0, 1-qP, ratio (Fi-F0)/(Fp-F0), and V were observed in dithiothreitol (DTT)-fed leaves compared to control ones under the same conditions. Hence photoinhibition caused by HI in bayberry was probably attributed to inactivation of PS2 RCs, and photoprotection from photodamage were mainly related to the xanthophyll cycle-dependent heat dissipation in excess photons.

Novel Guanidinium-Based Ionic Liquids for Highly Efficient SO2 Capture

The application of ionic liquids (ILs) for acidic gas absorption has long been an interesting and challenging issue. In this work, the ethyl sulfate ([C2OSO3](-)) anion has been introduced into the structure of guanidinium-based ILs to form two novel low-cost ethyl sulfate ILs, namely 2-ethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([C2(2)(C1)2(C1)2(3)gu][C2OSO3]) and 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([(C2)2(2)(C1)2(C1)2(3)gu][C2OSO3]). The ethyl sulfate ILs, together with 2-ethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([C2(2)(C1)2(C1)2(3)gu][NTf2]) and 2,2-diethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([(C2)2(2)(C1)2(C1)2(3)gu][NTf2]), are employed to evaluate the SO2 absorption and desorption performance. The recyclable ethyl sulfate ILs demonstrate high absorption capacities of SO2. At a low pressure of 0.1 bar and at 20 °C, 0.71 and 1.08 mol SO2 per mole of IL can be captured by [C2(2)(C1)2(C1)2(3)gu][C2OSO3] and [(C2)2(2)(C1)2(C1)2(3)gu][C2OSO3], respectively. The absorption enthalpy for SO2 absorption with [C2(2)(C1)2(C1)2(3)gu][C2OSO3] and [(C2)2(2)(C1)2(C1)2(3)gu][C2OSO3] are -3.98 and -3.43 kcal mol(-1), respectively. While those by [C2(2)(C1)2(C1)2(3)gu][NTf2] and [(C2)2(2)(C1)2(C1)2(3)gu][NTf2] turn out to be only 0.17 and 0.24 mol SO2 per mole of IL under the same conditions. It can be concluded that the guanidinium ethyl sulfate ILs show good performance for SO2 capture. Quantum chemistry calculations reveal nonbonded weak interactions between the ILs and SO2. The anionic moieties of the ILs play an important role in SO2 capture on the basis of the consistently experimental and computational results.

Low concentrations of NaHSO3 increase photosynthesis, biomass, and attenuate photoinhibition in Satsuma mandarin (Citrus unshiu Marc.) plants

Spraying low concentrated (0.5–5.0 mM) solutions of NaHSO3 on Satsuma mandarin (Citrus unshiu Marc.) leaves resulted in enhancement (maximal about 15 % at 1 mM NaHSO3) of net photosynthetic rate (PN) for 6 d. The potential photochemical efficiency of photosystem 2 (PS2, Fv/Fm) and the quantum yield of PS2 electron transport (ΦPS2) were increased under strong photon flux density (PFD). The slow phase of millisecond delayed light emission (ms-DLE) was increased, showing that the transmembrane proton motive force related to photophosphorylation was enhanced. We also observed that low concentrations of NaHSO3 promoted the production of ATP in irradiated leaves. We suggest that the increase in PN in Satsuma mandarin leaves caused by low concentrations of NaHSO3 solution may have been due to the stimulation of photophosphorylation and, hence, the increase in photochemical efficiency through speeding-up of PS2 electron transport. Photoinhibition of photosynthesis in leaves was modified by NaHSO3 treatment under high PFD. Hence the increase in leaf dry mass seems to be associated with the mitigation of photoinhibition caused by strong PFD.

Deep insights into the growth pattern of palladium nanocubes with controllable sizes

Although shape and size controllable palladium nanocrystals have attracted enormous attention, the growth behavior of Pd nanocubes is not thoroughly understood. In this work, the growth pattern of size controllable Pd nanocubes is studied systematically under a variety of reaction conditions. During the growth process of the Pd nanocubes, various structures including concave cubes, triangular bipyramids, pentagonal bipyramids (decahedrons) and pentagonal rods can be generated due to the disparate behavior of the fresh Pd atoms. Different-sized nanocubes are prepared controllably by changing the dosage of KBr, which provides capping capacities toward the {100} facets that the cubes are enclosed with. Both ascorbic acid (AA) and KBr influence the reducing rate of the Pd precursors and the growth kinetics of the nanocrystals, and furthermore control the morphologies of the products. This detailed research supplements the understanding of crystal growth, and provides insight toward the comprehension of atom movements at the nanoscale.

Densities and viscosities for the ternary system of cyclopropanemethanol (1) + 2, 2, 4-trimethylpentane (2) + decalin (3) and corresponding binaries at T = 293.15–323.15 K

ABSTRACT Densities (ρ) and viscosities (η) of a ternary system cyclopropanemethanol (1) + 2,2,4-trimethylpentane (2) + decalin (3) and three corresponding binary systems were measured at temperatures from 293.15 K to 323.15 K and atmospheric pressure. Densities were obtained by using a vibrating-tube densimeter. Viscosities were determined by an automatic microviscometer based on the rolling ball principle. The excess molar volumes () and viscosity deviations (Δη) of the ternary system were derived from the experimental data and then were fitted to Clibuka, Nagata–Tamura and Redlich–Kister equation, respectively. The binary subsystems were correlated by Redlich–Kister equation. The values of and Δη were used to discuss the nature of mixing behaviours between mixture components.

Influence of Reduction Kinetics on the Preparation of Well-Defined Cubic Palladium Nanocrystals

A facile synthesis strategy has been developed to synthesize palladium nanocubes with tunable size and well-controlled morphology. Through adjusting the dosages of acetate species (KOAc, NH4OAc, and HOAc), the sizes of well-defined Pd nanocubes are tuned. The reduction of Pd precursors, a first-order reaction, is influenceable by acetate species, and a quantitative relationship between cubic width and apparent reduction rate constant, which has been found to be an effective parameter to describe the growth process of Pd nanocubes, has been uncovered. The effect of apparent reduction rate constant on the growth of Pd nanocubes has been discussed, and the growth kinetics of Pd nanocubes is quantitatively depicted.