Applied Mechanics and Materials Vols. 295-298

Abstract: Total pigment and main monomeric anthocyanin contents in different cultivars of litchi (Litchi chinensis) were measured, HPLC fingerprints and similarity of litchi anthocyanins were analyzed, and a recovery process of litchi anthocyanins was developed. In 16 cultivars of litchi, the total anthocyanin content (absorbance at 510 nm) per gram pericarp was 0.490-3.045 in 2007 and 0.475-3.122 in 2008. The content of cyanidin-3-rutinoside (C3R), the most abundant monomeric anthocyanin in litchi pericarp, ranged from 724.6 (cv Yuhebao) to 7706.9 (cv Zhuangyuanhong) mg/kg, while the cyanidin-3-glucoside (C3G) content ranged from 1.3 (cv Guiwei) to 14.7 (cv Zhuangyuanhong) mg/kg. The anthocyanin profiles of the 16 cultivars were similar and the correlation coefficients were higher than 0.970, except for cv Gualv and cv Yuhebao. The recovery procedures for anthocyanins were as follows: 0.2-0.5% (v/v) of HCl as the extraction solvent, added to cover the surface of fresh pericarps, overnight extraction at ambient temperatures, and extracted twice, and purification by X-5 macroporous resin. The resulting litchi pigment contained 421.6 mg/g of C3R and 0.168 mg/g of C3G, which could be used as functional food ingredients.

Abstract: In order to have an insight into the reaction between acid rain and carbonate rock surface, and figure out the CO₂ carbonate source amount from the acid rain chemical weathering process of the carbonate rocks, two typical carbonate rock areas Guilin (represents limestone area) and Liuzhou (represents dolomite area) were chosen as the study areas in Guangxi. According to the dissolution rate calculated by the limestone test piece and GIS analysis, the CO₂ source produced by the acid rain was 41.066×10⁸g/a, in which Guilin was 33.349×108g/a and Liuzhou was 7.717×10⁸g/a. The carbon sources of unit area in Guilin and in Liuzhou were 66.967×10⁵g/a•km2 and 42.777×10⁵g/a•km2 respectively. Although the carbon sources were still less than their carbon sinks in Guilin and Liuzhou which were 273.891×105g/a•km2 and 43.660×105g/a•km2 respectively, they should not be neglected. There were two reasons that the degassing rate of carbon source in Guilin was slower than that in Liuzhou. One was the representative area of carbonate rock in Guilin were 2.77 times of that in Liuzhou, the other one was that the total intensity of acid rain of Guilin was lower than Liuzhou, so that the dissolution rate of the carbonate rocks was lower in Guilin.

Abstract: CdMnTe is one of the key materials for room temperature X-ray and gamma-ray detectors on Environmental Analysis and Monitoring. In this paper, the homogeneous Cd1-xMnxTe (x = 0.1) single crystal ingot was grown by the vertical Bridgman method. The compositional analysis was carried out by SEM/EDS. The Te inclusions were revealed by the IR transmission spectra. In dopant distribution was determined by ICP-AES measurement. The resistivity of CdMnTe was cha-racterized by I-V method. It was found that the segregation coefficient of Mn was 0.97. In dopant contents within 3 to 21 ppm of the ingot were found. The Te inclusions were mainly 8.2-28.3m in size and 1×105-1.5×107cm-3in concentration. I–V measurement reveals that sputtered Au film can form good ohmic contact and all the slices have the resistivity within 107 to 109Ωcm.

Abstract: Catalytic hydrolysis decomposition of dichlorodifluoromethane (CCl₂F₂) in the presence of water vapor and oxygen was studied over a series of solid acids using a fixed-bed reactor. Solid acid MoO₃/ZrO₂ displayed the highest activity, over which the conversion of CCl₂F₂ reached 100 % at 250 °C. CO₂ was the main-product and the selectivity to CClF₃ remained lower than 28.0 %. CO was not detected as by-product. The decomposition activity depended on the calcination temperature and the ZrO₂ content. The activity of solid acid MoO₃/ZrO₂ correlates well with its specific surface area and the amount of medium-strong acid sites on the surface. To explain the reaction mechanism for CCl₂F₂ catalytic decomposition over MoO₃/ZrO₂, a surface intermediate, O_surface-CF2-O_surface is proposed.

Abstract: The sol-gel process is applied to respectively prepare nano-TiO₂ films with Ce (cerium) or nano-TiO₂ films with Fe (ferium), which are used to degradate azo dye wastewater and present their characterization by XRD and HRTEM methods. The results show that proper amount of Ce or Fe doped into the nano-TiO₂ films can effectively accelerate the separation of photogenerated electrons-holes and easily form lattices, and consequently promotes nano-TiO₂ films' photocatalytic activity by nearly 20%.

Abstract: Preconditioning Refiner Chemic Alkaline Peroxide Mechanical Pulp (PRC-APMP) is one of the most currently used high yield pulps in China. During the bleaching of PRC-APMP, hydrogen peroxide is a commonly used bleaching agent. In order to improve the bleaching efficiency of PRC-APMP, urea was used as an activator in peroxide bleaching of aspen PRC-APMP. The results showed that the brightness of the urea-based bleached pulp higher than that without urea addition at the same hydrogen peroxide dosage. The physical properties such as the breaking length, tear index and fiber length of the bleached pulp were comparable to those without urea addition in peroxide bleaching.

Abstract: In this study, we proposed the use of distillers grains (DG) as a source for production of microcrystalline cellulose (MCC) due to its high content of cellulose. The main objective of this work was to extract the distillers grains microcrystalline cellulose (DMCC) particles and investigate the structure characteristic by SEM, XRD and FTIR. The images of SEM for DG and DMCC particles show clear differences with modifications of DG fiber structure. The acid hydrolysis changed the crystallinity index and crystallite sizes of the DMCC particles compared to their source materials. In addition, we observe a change in the crystalline structure from X-ray diffractograms. The intensity of each peak changed obviously, demonstrating structure transformation induced by acid hydrolysis took place during the preparation of DMCC.

Abstract: Lignin is depolymerized to small molecule aromatic compounds, which is regarded as one of the effective ways to achieve utilization of lignin resource. In this study, Al and Cu catalysts were loaded onto enzymolyzed straw lignin by the immersion method, and the product distribution of the catalytic pyrolysis of lignin was studied by GC-MS after being extracted by solvents. Results show that both Al and Cu catalysts can promote the lignin pyrolysis reaction. Based on the comparison of the product distribution without catalyst, Al catalyst is benefit to the formation of aromatic hydrocarbons, alcohols and phenols, while Cu catalyst contribute to the formation of hydrocarbons, alcohols and ketones.

Abstract: Bast fiber as raw material for bio-pulping has become a hot topic for its environmental-friendly and high quality fiber for paper in pulp and papermaking industry. In this paper, the reaction of the mulberry bast enzymatic pulping has been researched. It was treated with pectinase, find the best environmental factors, such as temperature and pH value, The results show that: from the changes of pectin content, pentosan content and Kappa number to determine the optimal temperature was 50°C, and pH value was 4.

Abstract: To qualify and quantify the flavonoids existing in Humulus scandens (Lour.)Merr., a Ultra performance liquid chromatography triple-quadrupole tandem mass spectrometer (UPLC-TQD) method was applied to preliminarily analyze the flavonoids exiting in Humulus. And a High performance liquid chromatography (HPLC) method was used to analyze the flavonoids existing in Humulus. Flavonoids in methanol extracts of Humulus were cleaned up by a C18 cartridge, separated by a PLASMA ODS column(5μm,250×4.6mm), with a gradient elution of methanol and 0.1% formic acid at a flow rate of 1 mL•min^-1 . Analytes were detected with ultraviolet detector (UV) at 280nm. Flavonoids, including Epicatechin, Luteolin-7-O-Glucoside, Vitexin or Apigenin-7-glucoside, Morin hydrate or Quercetin dehydrate and Luteolin were found in Humulus according to the UPLC-TQD. Results of HPLC analysis showed the linear ranges of 11 flavonoids were 0.1mg•L^-1-20mg•L^-1 with the correlation coefficient (r) all above 0.9909. Limits of detection (signal/ noise=3) was 100^{Superscript text} μg•L^-1. The average recoveries of all the compounds spiked at four levels of 200μg•L^-1, 500μg•L^-1, 1 mg•L^-1 and 1.5 mg•L^-1 were in the ranges of 70.8%-112.1%, 74.6%-116.6%, 73.1%-110.6%, 73.7%-99.9%, with the corresponding relative standard deviation (RSD, n=6) of 2.5%-5.8%, 0.8%-4.3%, 0.8%-3.7%, 1.7%-3.8%, respectively. This method ,which was proved to be precise, sensitive and reliable, could be applied to analyze flavonoids in leaves.