Microbial Community Diversity and Vertical Distribution in a Columnar Sediment of Maluku Strait

The sediment samples were collected from Maluku Strait at a depth of 1250 m, which is influenced by Mindanao Current and Indonesian Throughflow. Based on 16S rRNA clone libraries, the community structure and vertical distribution of archaea and bacteria were studied in a columnar sediment of 2m in length. From the surface sediment, 16S sequences were derived from fourteen bacterial phyla (Gammaproteobacteria, Planctomycetes, Alphaproteobacteria, Deltproteobacteria were dominant), but were limited to two groups of archaea: Crenarchaeota (99%) and Euryarchaeota (1%). Besides, 90% of the archaea clones were ammonia oxidation-related which indicated that the ammonia-oxidizing archaea might make a significant contribution to the chemosynthesis in the surface sediment. Contrastively in the bottom sediment, six bacterial phylogenetic groups were obtained (Gammaproteobacteria and Firmicutes were absolutely dominant), however no archaea 16S rRNA was detected. The microbial diversity of surface sediment was much higher than the bottom and seven unique bacterial phyla were obtained from two sediment respectively. The geochemical elements analysis revealed that the content of C, TOC and S in the surface sediment was much higher than the bottom, but the content of P is contrary. The microbial communities might be in response to the geochemical substance transfer and deposit influenced by the ocean current and it deserves further study compared with the other sediment samples in this area.

Highway constructions on the Qinghai-Tibet Plateau:Challenge,research and practice

Highway constructions on the Qinghai-Tibet Plateau(QTP)face great challenges induced by the unique local environmental,geological,and engineering conditions.The large area of permafrost,great temperature variability,strong UV rays,and complex geological conditions are the major factors that adversely influence the longterm performance of pavement systems.Since 1960s,Chinese engineers and researchers have started conducting research on the QTP to enhance the performance and durability of pavement systems.The present paper provide a comprehensive review of challenge,research and practice of highway constructions on the QTP including the special environmental and geological conditions,history of highway constructions on the QTP,major challenges and the state-of-the-art technology of subgrade constructions on permafrost,developments of the pavement structures and materials,performance prediction and maintenance methods of pavement surfaces,and applications of the research achievements on the first expressway on the QTP(i.e.,Gongyu Expressway).Based on the comprehensive literature review,it can be found that(1)frost heave and thaw weakening induced subgrade disease and longitudinal cracks on the pavement surface are complex coupled water-thermal-load problems.Engineering solutions are focusing on active cooling and thermal insulation methods,which can help to reduce temperature variations in the subgrade and thus improving its stability,(2)the harsh environmental and construction conditions may reduce the early strength and induce premature damage of cement-treated base materials.Some field validations showed that geocell-reinforced or asphalt-treated flexible base materials can provide better long-term performance,(3)the large temperature variability and strong UV rays can significantly accelerate aging of asphalt binders and greatly reduce the service life of asphalt mixtures.Various binder modification methods were developed for improving their viscoelasticity and enhance the low-temperature cracking resistance of pavement surface materials but are still lack of field validation data and comparisons of their life cycle costs.Therefore,it is recommended that a demonstration research project build test sections to examine a range of pavement structures and materials,and compare their long-term performance and life cycle costs,which can serve as important reference for future highway constructions on the QTP.

Effect of synthetic fibers on the mechanical performance of asphalt mixture:A review

Numerous studies showed that synthetic fibers are effective for reinforcing the mechanical performance of the asphalt mixture due to their high strength properties,ductility,and durability characteristics.In this paper,the objective is to present a review of the reinforcement effect of synthetic fiber on the mechanical performance of the asphalt mixture.This paper reviews the relevant literature on the characterizations and applications of synthetic fibers to improve different mechanical properties of asphalt mixes,which can provide a reference for the applications and development of synthetic fibers in asphalt pavement.The characteristics of common synthetic fibers are introduced and the utilization of synthetic fibers in asphalt mixture is discussed.Different surface treatment methods for fiber are reviewed and it is found that surface treatment can improve the performance of the synthetic fibers in asphalt mixtures,especially the chemical surface treatment method.The influence of synthetic fiber addition on the mechanical properties of the asphalt concrete such as rutting resistance,tensile strength,water stability performance,and cracking resistance are then discussed.The research results show that aramid,glass,and polyester fibers improve the fatigue cracking resistance of asphalt mixture.Polyester fibers,polyamide fibers,and carbon fibers are used to improve resistance to the permanent deformation of asphalt pavement.

藻红蛋白的高效异源生物合成及其生物活性

[目的]实现藻红蛋白在大肠杆菌中的高效生物合成。[方法]将藻红蛋白生物合成的多个基因构建到单一表达质粒上,质粒转化大肠杆菌后获得表达菌株,优化诱导物、诱导温度和诱导时长等发酵条件,利用亲和层析法分离纯化重组藻红蛋白,分析重组蛋白的光谱学性质与抗氧化活性。[结果]获得了高效生物合成藻红蛋白的大肠杆菌菌株,以乳糖为诱导物时最佳诱导条件为:2.0 g/L的乳糖、25℃下诱导28 h,藻红蛋白表达量达211.6 mg/L;以IPTG为诱导物时最佳诱导条件为:0.4 mmol/L的IPTG,在25℃条件下诱导28 h,藻红蛋白表达量达188.7 mg/L。藻红蛋白色基结合率达92.0%,OD555/OD280为8.0。[结论]成功实现了藻红蛋白在大肠杆菌中的高效生物合成,重组藻红蛋白具有羟基自由基的清除活性。

Review of ice-pavement adhesion study and development of hydrophobic surface in pavement deicing

Ice adhesion to materials is a significant concern in many fields. Hydrophobic surface has been used for anti-icing in fields of aircraft or transmission line, which prove to be efficacious and economical. However, such technique is seldom employed for road deicing, because of the texture and service environment of pavement. Instead, deicers such as rock salt are frequently used, which leads to serious corrosion problem of roads and bridges. In this paper, a number of studies that characterize mechanism of ice adhesion to common substrates, specifically to pavement, are reviewed. The most important researches undertaken on ice adhesion strength affecting factors are presented. An overview of studies carried out to find hydrophobie surface for asphalt and cement concrete pavement antiicing are presented. It was verified that the hydrophobicity had high correlation with icephobicity, and nano-engineered asphalt and cement concrete pavement surface exhibited favorable hydrophobicity, and also had good performance on weakening pavement-ice bonding. However, most ice-repelling pavements obtain hydrophobic surface via low surface energy coating, which could not exist on pavement for a long time under wheel abrasion. And the nano/micro structures on hydrophobic surfaces are also vulnerable and consumable. Thus, the long-term effect of hydrophobic surface still need to be improved, and durability of the hydrophobic surface should be the research and development priorities of ice-repelling pavement.

DMSO/DBU/CO2溶剂体系中原位有机功能催化纤维素碳酸酯的合成及其性质研究

纤维素是地球上储量最丰富的生物可再生资源,具有价格低廉、易改性、可生物降解等特点.纤维素衍生化是拓展纤维素应用的重要手段之一.纤维素碳酸酯是重要的纤维素衍生物之一,在包装材料、热塑性材料、固体电解质等领域具有重要的应用潜力.本文基于1,8-二氮杂二环十一碳-7-烯(DBU)/二甲基亚砜(DMSO)/CO_2体系溶解活化纤维素,通过原位DBU的有机功能催化作用催化纤维素与碳酸二甲酯之间的转酯化反应,合成了纤维素甲基碳酸酯.结果表明,碳酸二甲酯与纤维素脱水葡萄糖单元(AGU)摩尔比为8:1,反应温度为60℃,反应时间为12 h时,可得到取代度(DS)1.09的纤维素碳酸酯,并通过核磁共振、红外光谱、热重分析(TGA/DSC)等表征方法研究纤维素碳酸酯结构与热性能的关系.DSC/TGA结果显示,当纤维素甲基碳酸酯的取代度为1.09时,其玻璃化转变温度为62.9℃,起始降解温度为305.5℃.