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Based on shot-peening hardness tests performed on carburized gear steel,the hardness effectiveness of shot-peening on tooth flank and root is studied,it is aimed to find out the factors and parameters which are related to surface roughness in different shot-peening process parameters,so that rational parameter combination of enhanced shot-peening can be available to provide guidance to enhanced shot-peening on other parts.

The wood-plastic foamed composites have lower density and higher specific strengths than wood-plastic composites (WPC) and thus have wide applications in fields such as building, decoration, packing, and the automobile industry. Previous studies showed that the weathering causes color fading, strength weakening, chemical changes of WPC, thereby restricting the specific outdoor applications of WPC. In order to explore their weathering mechanism and broaden their outdoor applications, it is of great importance to evaluate the durability of BF/PP foamed composites. The objective of this research was to study the impact of weathering of freeze-thaw cycle on the physical and thermal properties of bamboo flour-polypropylene foamed composite. The foamed composites of bamboo flour (BF), high melted strength polypropylene (HMSPP), polypropylene (PP), 1% modified azodicarbonamide (AC) foaming agent, and maleic anhydride grafted polypropylene (MAPP) coupling agent blends were prepared by injection molding. The composites with different BF contents of 0, 20%, 33% and 42% were exposed to accelerated cycling of water immersion followed by freeze thaw at the temperature of -40-60°C for 0, 3, 6, and 9 cycles. The effects of freeze-thaw cycles accelerated weathering on the color change and the physico-mechanical properties and thermal behavior of the foamed composites were investigated. The surfaces morphology of composites non-weathered and freeze-thaw cycles weathered were investigated by (Environmental Scanning Electronic Microscopy, ESEM) and the chemical structures were also analyzed by FTIR. The results showed that the composites at higher BF content exhibited greater color change and larger decreases in physico-mechanical properties especially the tensile and impact strengths as compared to the one without weathering. The negative effects of the weathering increased with the growing number of freeze-thaw cycles. The color change ΔE* of 0, 20%, 33%, and 42% BF/PP composites after nine times freeze-thaw cycles were 0.9, 2.4, 7.0, and 9.9, respectively. The corresponding lightness change ΔL*, redness change Δa*, and yellowness change Δb* of 42% BF/PP composite were 8.7, 1.3, and 4.7, respectively. The retentions of flexural modulus, and bending, tensile, and notched impact strengths of 0%, 20%, 33%, and 42% BF/PP composites were 95.2% - 99.1%, 97.3% - 98.9%, 94.9% - 97.5%, and 92.0% - 95.6%, respectively. The freeze-thaw cycles slightly affected the thermal behavior of composites as the initial temperature of thermal decomposition (Ti) for the 0% and 33% BF/PP foamed composite after nine times freeze-thaw cycles reduced by 19°C and 8°C, respectively. ESEM observation revealed that the surfaces of freeze-thaw cycles weathered composites were no longer smooth; and the micro cracks and folds appeared; meanwhile, some parts of the polymers layers dropped off. FTIR analysis indicated that the wood index (the ratio of the peak intensity at 2 912 cm-1 and the peak intensity at 1 023 cm-1) reduced and the bamboo particles of the composites surfaces lost and the intensity of the groups for PP decreased due to the freeze-thaw cycles weathering. [ABSTRACT FROM AUTHOR]

In order to reduce the density and improve the toughness of wood-plastic composite (PC), the foamed PC was made through adding chemical foaming agent in this study. To fully utilize bamboo resources in China and reduce white pollution, the foamed composite with 54% PPM and 13% HMSPP containing 33% bamboo powder and 1% modified azodicarbonamide (AC) foaming agent blends by weight was made by injection molding. Furthermore, the aging performance of bamboo powder/polypropylene (PP) foamed composites was studied in order to investigate the weathering mechanism of WPC and to strengthen its production and quality management and thus expand its application fields. The composites were exposed to 1 200 h accelerated xenon-arc radiation with water spray, the mechanical characteristics including bending performance, notched impact strength, and color change of composites were studied. The rheological behavior of composites with regard to frequency sweep ranges from 0.01 to 70 Hz at 195? was observed. The surface morphology of composites with non-weathered and weathered for 1 200 h were investigated by ESEM and their chemical structures were analyzed by FTIR. The results showed that the mechanical properties of composites decreased significantly for weathering 300 h and decreased continuously with an increase of exposure time. The retentions of residual bending strength, flexural modulus and notched impact strengths were only 79.4%, 68.3% and 75.6% respectively. The weathering also resulted in significant color fading of the composites, especially for the first 900 h. The color began to change slowly within the next 300 h. After weathering for 1 200 h, the color change ΔE*, lightness change ΔL*, redness change Δa* and yellowness change Δb* were 49.0, 48.4, -5.9 and -4.9 respectively. The frequency sweep results indicated that the storage modulus, loss modulus and complex viscosity of composite weathered for 1 200 h decreased and the intersection value of energy storage modulus and loss modulus become lower, and the corresponding frequency was higher. These results indicated that the molecular weight distribution become wider and the molecular weight became lower. The ESEM observation revealed that the surface of weathered composite was no longer smooth; and the cracks and holes appeared and some bamboo fibers exposed. The FTIR analysis showed the new peak of C=O stretching vibration at 1 717 cm-1 appeared and C=C absorption peak at 1 459 cm-1 strengthened and C=O stretching vibration peak at 1 059 cm-1 also strengthened. The FTIR result verified the photooxidation and photodegradation of composites for accelerated weathering. [ABSTRACT FROM AUTHOR]

Dissolved pulp refers to pulp of high cellulose content which is used to manufacture various cellulose-derived products such as regenerated fibers or films (e.g., Viscose, Lyocell), cellulose esters (acetates, propionates, butyrates, nitrates) and cellulose ethers (carboxymethyl-, ethyl-, methyl-celluloses). With the rapid development of the global economy and a constant increase in population, the overall demand for dissolved pulp is rising. Dissolved pulp is generally made by the prehydrolysis kraft and acid sulfite processes comprising additional purification stages such as hot and cold caustic extraction. Dilute sulfuric acid is the most commonly used solvent for prehydrolysis of biomass to produce the dissolved pulp. However, cellulose is seriously degraded and the equipment is corroded while the prehydrolysis with sulfuric acid is performed. Oxalic acid, as an organic acid, has a better prehydrolysis selectivity than some mineral acids such as sulfuric acid or hydrochloric acid. The purpose of this paper is to clarify bamboo lignin removal during the bamboo prehydrolysis with oxalic acid to improve the prehydrolysis process for dissolved pulp. The acid-insoluble lignin contents were determined with 72% H2SO4 according to the TAPPI standard test method (T 222 om-06) at different prehydrolysis periods. The distribution of pseudo-lignin on the surface of bamboo fibers was observed by FE-SEM. The chemical structural changes of bamboo lignin were studied by means of CP/MAS 13C-NMR. The results show that the yield decreased with the extension of prehydrolysis time as most of the hemicellulose and a little of the lignin and cellulose were degraded under the acid prehydrolysis conditions. As an increased amount of oxalic acid was applied for prehydrolysis, an increased drop of the yield was obtained. The lignin content based on the prehydrolysed bamboo chips increased with the extension of prehydrolysis time due to a predominant degradation of hemicellulose, the increased amount of oxalic acid and the higher lignin content. However, the lignin content based on the bamboo chips increased dramatically after an initial decline with the extension of prehydrolysis time due to the condensation between the lignin degradation products and carbohydrates, and the formation of pseudo-lignin. As an increased amount of oxalic acid was used for prehydrolysis of bamboo, a greater increase in the rate of lignin content was obtained. The bamboo lignin has more phenolic hydroxyls due to the breakdown of aryl-ether bonds (β -O-4) during the oxalic acid prehydrolysis of bamboo. The pseudo-lignin originating from carbohydrates including cellulose and hemicellulose could attach to the surface of bamboo fibers in the form of microspheres. [ABSTRACT FROM AUTHOR]

ZnCl2 • 4H2O solution was used as a common solvent of cellulose and chitosan and cellulose / chitosan / ZnCl2 • 4H2O solution was prepared. The effects of temperature, mass fraction of raw materials and shearing frequency on the rheological properties of cellulose / chitosan / ZnCl2 • 4H2O solution were investigated. The results show that the entanglement points between the macromol ecular chains in solution at high temperatures are easier to untwist thus the flow resistance decreased and the entanglement increase with the increase of mass fraction of chitosan / cellulose. As a result the apparent viscosity, structural viscosity index, zero shear viscosity, storage modulus and loss modulus decrease with the increase of temperature and increase with the increase of mass fraction of chitosan / cellulose. The apparent viscosity of cellulose / chitosan / ZnCl2 • 4H2O solution decreases, while the storage modulus and loss modulus increase with the increase of shearing frequency. [ABSTRACT FROM AUTHOR]

A method was developed for the determination of cylindrospermopsin (CYN), nodularin (NOD), microcystin-RR (MC-RR), microcystin-YR (MC-YR) and microcystin-LR (MC-LR) in freshwater fish by dispersive solid phase extraction-liquid chromatography-tandem mass spectrometry (DSPE-LC-MS/MS). The analytes were extracted from fish tissues with acetonitrile-water-formic acid (89:10:1, v/v/v), and purified by DSPE using C 18 as the adsorbent. The separation of analytes was performed on an Agilent ZORBAX Eclipse XDB C 18 column with the gradient elution of acetonitrile and water as mobile phases. Qualitative analysis was performed using the multiple reaction monitoring (MRM) mode. The analytes were quantified by matrix-matched external standard curves. The chromatographic and MS parameters were optimized. Major factors affecting the extraction and cleanup efficiencies including the type of extraction solvent and cleanup sorbent were investigated. The linear correlation coefficients ( R 2 ) of the five target compounds were no less than 0.9954. The limits of detection (LODs, S/N =3) and limits of quantification (LOQs, S/N =10) of the five target compounds were 5-10 μg/kg and 15-40 μg/kg, respectively. The spiked recoveries of the five target compounds ranged from 62.3% to 101.2%. The developed method is simple, rapid, accurate, sensitive, and is suitable for the determination of cylindrospermopsin, nodularin and microcystins in freshwater fish.

To study the expression of X-linked inhibitor of apoptosis protein (XIAP) and cell apoptosis in vitro model of acute pancreatitis (AP), we carried out experiments to stimulate AR42J cell line with caerulein (10(-8) mol/L) for 12 hours, then collected cells at various time points (0 h, 4 h, 8 h, 12 h, and 24 h, respectively). We then observed the morphologic changes of AR42J cells with the stimulation of caerulein with electronic microscope. The gene expression of XIAP, caspase-3 and caspase-9 was detected using real-time fluorescence quantitative polymerase chain reaction (FQ-PCR), and the protein expression of XIAP was assessed by western blot. The activation of nuclear factor-kappa B (NF-kappaB) was measured by flow cytometry (FCM). With the stimulation of caerulein, the expression of XIAP and the NF-kappaB activation could first decrease and then increase, but the change of caspase-3 and caspase-9 expressions were opposite. XIAP may inhibit the cell apoptosis in rat pancreatic acinus AR42J cell lines at first with the stimulation of caerulein, then NF-kappaB can upgrade the expression of XIAP and increase the cell apoptosis.