国产环氧沥青混合料固化强度增长规律研究

研究了环氧沥青混合料的强度形成机理,在此基础上对影响环氧沥青混合料强度的两个重要因素即混合料的容留时间、养生温度进行了研究,确定了不同温度下环氧沥青混合料的容留时间范围及强度增长规律;采用差示扫描量热法(DSC)测得环氧沥青结合料在不同升温速率下的动态DSC曲线,通过非线性回归求得固化动力学关键参数,建立环氧沥青结合料的固化反应模型。研究结果可以指导环氧沥青混合料的生产与施工,同时对铺装层开放交通时间的确定有参考意义。

Determination of dynamic modeⅠfracture toughness of rock at ambient high temperatures using notched semi-circular bend method

To investigate the influence of loading rate and high temperature on the dynamic fracture toughness of rock,dynamic fracture tests were carried out on notched semi-circular bend specimens under four temperature conditions based on the split Hopkinson pressure bar system.Experimental and analytical methods were applied to investigating the effect of temperature gradient on the stress waves.A high-speed camera was used to check the fracture characteristics of the specimens.The results demonstrate that the temperature gradient on the bars will not significantly distort the shape of the stress wave.The dynamic force balance is achieved even when the specimens are at a temperature of 400°C.The dynamic fracture toughness linearly develops with the increase of loading rate within the temperature range of 25-400°C,and high temperature has a strengthening effect on the dynamic fracture toughness.

Regeneration of Spent Activated Carbon by Yeast and Chemical Method

In this study,spent activated carbon(AC) saturated with caramel was regenerated by using yeast and NaOH.The efficiency of regeneration was evaluated under parameters such as amount,treatment time,temperature,pH value,stirring temperature of yeast and NaOH concentration.The optimum condition for AC regeneration was 8 h for yeast treatment time,35 ℃ for 0.075% yeast culture temperature,a pH value of 6 for the yeast dealing with the spent AC,90 ℃ for NaOH stirring temperature of AC and 6% NaOH for washing after the spent AC was treated by yeast.Under these conditions,methylene blue(MB) adsorption was 213 mg·g-1 in comparison with 60 mg·g-1 of spent AC.The micro structure and surface area of the regenerated AC were characterized by scanning electron mi-croscope(SEM) and N2 sorption,respectively.The pore size distributions of virgin and regenerated AC were ana-lyzed by means of H-K equation,resulting in a mean pore diameter of 1.28 nm and a pore volume of 1.13 cm3·g-1.This study provides data for theoretical support of the AC regeneration technology.

Preparation of boric acid from low-grade ascharite and recovery of magnesium sulfate

Boric acid and kieserite were prepared from low-grade ascharite by sulfuric acid method.This method results in the recovery of 71.06%and 45.03%for boric acid and kieserite,respectively.Meanwhile,the boric acid was precipitated from the filtrate at low temperature and the solution was recycled without discharging waste liquid in the whole process.The influence of amount of sulfuric acid,mass fraction of sulfuric acid,reaction temperature and reaction time on the leaching rate of boric acid were studied. The results show that the leaching rate of boric acid reaches 93.80%under the following conditions:the amount of sulfuric acid is 85%of theoretical dosage;the mass fraction of sulfuric acid is 25%;reaction temperature is 95℃;and the reaction time is 100 min. Meanwhile,the effects of mass fraction of magnesium sulfate,crystallization temperature and crystallization time on the crystallization of kieserite were investigated and the optimal crystallization conditions are obtained:the mass fraction of magnesium sulfate is 28%;the crystallization temperature is 180℃and the crystallization time is 4h.

High efficiency production of ginsenoside compound K by catalyzing ginsenoside Rb1 using snailase

The rare ginsenoside Compound K （C-K） is attracting more attention because of its good physiological activity and urgent need. There are many pathways to obtain ginsenoside C-K, including chemical and biological methods. Among these, the conversion of PPD-type ginsenosides by enzymatic hydrolysis is a trend due to its high efficiency and mild conditions. For effectively extracting from the other panaxadiol saponins, the conversion process for ginsenoside C-K was investigated using snailases in this study. The univariate experimental design and response surface methodology were used to determine the optimal hydrolysis conditions for the conversion of ginsenoside Rbl into ginsenoside C-K by snailases. The optimum conditions were as follows： pH 5,12, temperature 51 ℃, ratio of snailase/substrate 0.21, and reaction time 48 h. On the basis of these parameters, the addition of 1.0 mmol· L- 1 ferric ion was found to significantly improve the enzymolysis ofsnailases for the first time. With the above conditions, the maximum conversion rate reached 89.7%, suggesting that the process can obviously increase the yield of ginsenoside C-K. The bioassay tests indicated that the ginsenoside C-K showed anti-tumor activity in a series of tumor cell lines. Based on these results, we can conclude that the process of rare ginsenoside C- K production by enzymolysis with snailase is feasible, efficient, and suitable for the industrial production and application.

Real-time horizontality adjusting and control system of a large platform applied to satellite experiment

In order to satisfy a satellite horizontality requirement in an experiment, it is indispensable to monitor and adjust the horizontality of a large platform loading the satellite under the condition of ultra-low temperature with real time. So the control system design and control strategy are described in detail to accomplish the horizontality monitoring and adjusting. The system adopts the industry control computer as the upper computer and the SIEMENS S7-300 PLC as the lower computer. The upper computer that bases on industry configuration software IFIX takes charge of monitoring the platform and puts forward the control strategy. PLC takes charge of receiving the adjusting instructions and controlling the legs moving to accomplish the horizontality adjusting. The horizontality adjusting strategy is emphasized and the concept of grads is introduced to establish a mathematics model of the platform inclined state, so the adjusting method is obtained. Accordingly the key question of the automatic horizontality adjusting is solved in this control system.

Conditions for enzymatic hydrolysis of egg white proteins

The study on condition for enzymic hydrolysis of in egg white proteins using a dual quadratic rotary, orthogonal and regressive design shows that the optimum temperature was 68 5 ℃, and the optimum pH is 8 21 at the substrate concentration of 5 5%. Mathematic model has been established to reveal the relationship between enzyme concentration and hydrolytic time with respect to the same NR.

Dissolution kinetics of malachite in ammonia/ammonium sulphate solution

The dissolution kinetics of malachite was investigated in ammonia/ammonium sulphate solution. The effects of ammonia and ammonium sulphate concentration, pH, leaching time, reaction temperature, and particle size were determined. The results show that the optimum leaching conditions for malachite ore with a copper extraction more than 96.8% are ammonia/ammonium concentration 3.0 mol/L NHaOH ＋ 1.5 mol/L （NH4）2SO4, liquid-to-solid ratio 25：1 mL/g, leaching time 120 min, stirring speed 500 r/rain, reaction temperature 25 ℃ and particle size finer than 0.045 mm. The dissolution process of malachite with an activation energy of 26.75 k J/tool is controlled by the interface transfer and diffusion across the product layer. A semi-empirical rate equation is obtained to describe the leaching process and the reaction orders with respect to concentration of ammonia and ammonium sulphate are 2.983 0 and 0.941 1, respectively.

DNA-assisted rational design of BaF_2 linear and erythrocyteshaped nanocrystals

The synthesis of inorganic materials with special morphologies with the assistance of biological molecules is a potential development in the field of controllable growth and assembly of nanomaterials. In this paper, BaF2 nanocrystals in patterns of well-defined linear and erythrocyte-shaped structure were synthesized with the assistance of Escherichia coil DNA. Morphology and the arrangement of BaF2 particles on DNA were controllable by altering the reaction condition. Square nanoparticles arranged in linear chains were gained with the assistance of normal DNA; while, erythrocyte-shaped BaF2 nanospheres were synthesized with the assistance of denatured DNA. Besides, the influences of solvent, reaction temperature, concentration of reactants and the heating time on the morphology of the BaF2 particles were studied.

Research on the Ultrasonic Extraction Technology of Cottonseed Oil

[ Objective ] To optimize the ultrasonic extraction technology of cottonseed oil by response surface methodology. [ Method ] Based on the single factor experiment, the response surface method with three factors at three levels was adopted according to the principle of central composite design, The optimum extraction conditions of extraction duration, liquid-solid ratio and temperature were determined by regression analysis. [ Re- salt] The best ultrasonic extraction conditions of cottonseed oil were 35 min of extraction duration, 38 ℃ of extraction temperature and 56：6 of liquid-solid ratio. Under these conditions, the extraction rate of cottonseed oil could reach up to 45.81%, with a relative error of 0.13% from the theoreti-cal value of 45.94%. [ Conclusion] The method optimized the extraction technology and laid foundation for the further research of cottonseed oil. Key words Cottonseed oil; Ultrasonic extraction; Response surface method; China

Reduction smelting on bismuth oxide residue in FeO-SiO2-CaO ternary slag system

Reduction smelting of the bismuth oxide residue from pressure leaching of bismuth sulfide was investigated in the FeO-SiO_2-CaO ternary slag system.The results show that all the recovery ratios of Bi,Ag,Cu and Pb increase with the increase of reductive coal proportion,reaction temperature and time,while too much reductive coal would help Fe enter metal phase;CaO/SiO_2and Fe O/SiO_2 of the chosen slag system should be 0.5-0.75 and 1.25-1.75,respectively,for the reason that the slag system has the optimum mobility and is beneficial for the recovery of metals.The corresponding optimum conditions are determined as follows:the added coal proportion is 7%of the leaching residue,CaO/SiO_2 mass ratio in the chosen slag system is 0.5 and FeO-SiO_2 is 1.5,the reaction temperature is 1300°C and the reaction time is 40 min.Under the above conditions,the recovery ratios of Bi,Ag,Cu and Pb are 99.6%,99.8%,97.0%and 97.3%,respectively.

Utilization Starch of Avocado Seed （Persea Americana Mill.） as a Raw Material for Dextrin

Starch ofavocado seeds can be used as an alternative source of starch because it contains 80.1% starch. Natural starch can be made into a modified starch, for example dextrin. Dextrin can be made by using acid or enzyme hydrolysis. The purposes of this research were determine the concentration of hydrochloric acid （HCl）, the temperature and heating timein the optimum process of hydrolysis of starch into dextrin and to determine the quality of the resulting product dextrin terms of Indonesian National Standard 01-2593-1992. The methode was used in this research is hydrolisis with hydrochloric acid （HCl）. The results processing into starch avocado seed yield is 23.15%. HCl concentration, temperature and heating time significantly affect the value of dextrose equivalent （DE）, viscosity and part soluble in cold water. There is interaction between HCl concentration, temperature and heating time on the value of DE, viscosity and part soluble in cold water. Optimum conditions of process was obtained at a concentration of 0.15 N HCl, 30 minutes heating time and heating temperature of 90 ℃. Dextrose equivalent （DE） value is 19.61%. The value of solubility in cold water is 90.19%. Viscosity value is 1.61 ° E. Dextrin is not accordance with the standards of quality parameters Indonesian National Standard 01-2593-1992. Dextrin produced should be applied to non-food industry.

Distributed Algorithm for Robust Resource Allocation with Polyhedral Uncertain Allocation Parameters

This paper studies a distributed robust resource allocation problem with nonsmooth objective functions under polyhedral uncertain allocation parameters. In the considered distributed robust resource allocation problem, the（nonsmooth） objective function is a sum of local convex objective functions assigned to agents in a multi-agent network. Each agent has a private feasible set and decides a local variable, and all the local variables are coupled with a global affine inequality constraint,which is subject to polyhedral uncertain parameters. With the duality theory of convex optimization,the authors derive a robust counterpart of the robust resource allocation problem. Based on the robust counterpart, the authors propose a novel distributed continuous-time algorithm, in which each agent only knows its local objective function, local uncertainty parameter, local constraint set, and its neighbors＇ information. Using the stability theory of differential inclusions, the authors show that the algorithm is able to find the optimal solution under some mild conditions. Finally, the authors give an example to illustrate the efficacy of the proposed algorithm.

Interaction between temperature and photoperiod in regulation of flowering time in rice

Photoperiod and temperature are two pivotal regulatory factors of plant flowering. The floral transition of plants depends on accurate measurement of changes in photoperiod and temperature. The flowering time of rice （Oryza sativa） as a facultative short-day （SD） plant is delayed under long-day （LD） and/or low temperature conditions. To elucidate the regulatory functions of photoperiod and temperature on flowering time in rice, we systematically analyzed the expression and regulation of several key genes （Hd3a, RFT1, Ehdl, Ghd7, RID1/Ehd2/OsIdl, Se5） involved in the photoperiodic flowering regulatory pathway under different temperature and photoperiod treatments using a photoperiod-insensitive mutant and wild type plants. Our re- sults indicate that the Ehdl-Hd3a/RFT1 pathway is common to and conserved in both the photoperiodic and temperature flow- ering regulatory pathways. Expression of Ehdl, Hd3a and RFT1 is dramatically reduced at low temperature （23~C）, suggesting that suppression of Ehdl, Hd3a and RFT1 transcription is an essential cause of delayed flowering under low temperature con- dition. Under LD condition, Ghd7 mRNA levels are promoted at low temperature （23~C） compared with normal temperature condition （28℃）, suggesting low temperature and LD treatment have a synergistic role in the expression of Ghd7. Therefore, upregulation of Ghd7 might be a crucial cause of delayed flowering under low temperature condition. We also analyzed Hdl regulatory relationships in the photoperiodic flowering pathway, and found that Hdl can negatively regulate Ehdl transcription under LD condition. In addition, Hdl can also positively regulate Ghd7 transcription under LD condition, suggesting that the heading-date of rice under LD condition is also regulated by the Hdl-Ghd7-Ehdl-RFT1 pathway.

Shock tube study of kerosene ignition delay at high pressures

Ignition delay times of China No.3 aviation kerosene were measured behind reflected shock waves using a heated high-pressure shock tube.Experimental conditions covered a wider temperature range of 820-1500 K,at pressures of 5.5,11 and 22 atm,equivalence ratios of 0.5,1.0 and 1.5,and oxygen concentration of 20%.Adsorption of kerosene on the shock tube wall was taken into account.Ignition delay times were determined from the onset of the excited radical OH emission in conjunction with the pressure profiles.The experimental results of ignition delay time were correlated with the equations:11 0.22 1.09 2 3.2 10 [Keros ene ] [O2] exp(69941 RT) and 7 0.88 0.23 4.72 10 P exp(62092 RT).The current measurements provide the ignition delay behavior of China No.3 aviation kerosene at high pressures and air-like O2 concentration.

Sequential protocol for C(sp)-H carboxylation with CO_2:KO^tBu-catalyzed C(sp)-H silylation and KO^tBu-mediated carboxylation

CO_2 incorporation into C-H bonds is an important and interesting topic. Herein a sequential protocol for C(sp)-H carboxylation by employing a metal-free C-H activation/catalytic silylation reaction in conjunction with KO^tBu-mediated carboxylation with CO_2 was established, in which KO^t Bu catalyzes silylation of terminal alkynes to form alkynylsilanes at low temperature, and simultaneously mediates carboxylation of the alkynesilanes with atmospheric CO_2. Importantly, the carboxylation further promotes the silylation, which makes the whole reaction proceed very rapidly. Moreover, this methodology is simple and scalable, which is characterized by short reaction time, wide substrate scope, excellent functional-group tolerance and mild reaction conditions,affording a range of corresponding propiolic acid products in excellent yields in most cases. In addition, it also allows for a convenient ^(13)C-labeling through the use of ^(13)CO_2.