Optimization of corn-stalk skin flake-wood shaving composite technology

We focused on the optimization of corn-stalk skin flake-wood shaving composite technology. We studied the effects of material-mixture ratio, glue content, hotpressing temperature, and hot-pressing time on the appearance, physical, and mechanical properties of the composite by the orthogonal experiment method. Our findings yielded highly significant results in all three cases: the effects of the material-mixture ratio on 2 h of thickness swelling(2h TS)and the modulus of rupture(MOR); the effects of glue content on 2h TS, internal bond strength, and modulus of elasticity(MOE); and the effects of hot-pressing temperature on MOR and MOE. Product optimization is achieved when the ratio of corn stalk skin flake to wood shaving is 3:7, the glue content is 12 %, the hot-pressing temperature is 150 °C, and the hot-pressing time is 4.5 min.

Robust Image Hashing via Random Gabor Filtering and DWT

Image hashing is a useful multimedia technology for many applications,such as image authentication,image retrieval,image copy detection and image forensics.In this paper,we propose a robust image hashing based on random Gabor filtering and discrete wavelet transform(DWT).Specifically,robust and secure image features are first extracted from the normalized image by Gabor filtering and a chaotic map called Skew tent map,and then are compressed via a single-level 2-D DWT.Image hash is finally obtained by concatenating DWT coefficients in the LL sub-band.Many experiments with open image datasets are carried out and the results illustrate that our hashing is robust,discriminative and secure.Receiver operating characteristic(ROC)curve comparisons show that our hashing is better than some popular image hashing algorithms in classification performance between robustness and discrimination.

Properties of paper mill sludge–wood fiber–HDPE composites after exposure to xenon-arc weathering

We used paper mill sludge(PMS) to substitute for part of the wood fibers(WF) used to reinforce high density polyethylene(HDPE).The resulting composites were subjected to xenon-arc weathering.The composite filled with limited PMS(under 10 %) had mechanical properties and aging resistance similar to those without PMS.The composites containing more PMS faded and cracked more readily than those without PMS.Based on the carbonyl index,crystallinity,and wood index,PMS appeared to accelerate the degradation of composites during weathering.Adding PMS to WF–HDPE composites reduced the weathering resistance,and this reduction was not significant if the PMS content did not exceed 20 % of the wood fibers.Therefore,PMS could be used as a reinforcement in wood-plastic composites at levels less than20 % of the wood fiber content.

Effects of Nitrogen Exponential Fertilization on Growth and Nutrient Concentration of Hydrangea macrophylla Seedlings

Slow growth rate restricts the development and growth of seedlings due to nutrients deficiency or nutrient imbalance.Exponential fertilization can enhance the internal nutrient reserves in seedlings at the nursery-stage and strengthen their resistance to adverse conditions.In this study,nitrogen requirements for producing Hydrangea macrophylla‘Hanatemari’that robust seedlings,nutrient dynamics,biomass and growth,was examined utilizing exponential fertilization.The potted seedlings were fertilized with urea under exponential regime at rates of 0.5,1.5 and 2.0 g nitrogen/plant(EF1,EF2,and EF3),respectively.In addition,an unfertilized group treated with equal volume of deionized water was used as control.The results showed that seedlings under 1.5 g N/plant(EF2)had the highest plant growth index and total biomass.The nutrient concentrations of different organs varied in different fertilization treatments.Based on the results of current study,it is concluded that 1.5 g N/plant(EF2)is suitable exponential fertilization treatment for the culture of hydrangea seedlings.Our treatments results showed that 2.0 g N/plant is not suitable for seedling culturing,because of serious nutrient toxicity.These findings will help to improve seedling quality and strengthen the production of H.macrophylla for plantation.

纳米纤维素限域钯纳米颗粒的室温催化活性及化学选择性

本文利用水合低共熔溶剂结合超声法制备了羧基化纤维素纳米纤丝(CNF),并利用其表面的羧基官能团为反应活性位点原位合成了具有均匀分散性和高负载量(9.6 wt%)的CNF-Pd复合催化剂.研究结果表明:CNF-Pd具有显著的限域特性,包括在CNF表面羧基官能团上原位固定生长Pd纳米颗粒的化学限域和CNF冷冻干燥过程中自组装形成的空间结构限域.CNF-Pd在4-硝基苯酚加氢模型反应中表现出优异的室温催化活性,其最高速率常数为8.8×10^-3s^-1,最高催化活性的转化频率为2640 h^-1.CNF-Pd催化剂在水性介质中显示出良好的化学稳定性和可回收性,至少重复使用6个循环不会失活.此外,CNF-Pd催化剂还可实现3-硝基苯乙烯在醇/水共溶剂中向3-氨基苯乙烯的化学选择性加氢,且具有80%–98%的高选择性产率.综合上述结果,CNF在构建具有高室温催化活性及可回收利用的金属纳米颗粒催化剂方面具有广泛应用潜力和发展空间.