Formation of Arrayed Droplets by Soft Lithography and Two-Phase Fluid Flow, and Application in Protein Crystallization

This paper presents an overview of our recent work on the use of soft lithography and two-phase fluid flow to form arrays of droplets. The crucial issues in the formation of stable arrays of droplets and alternating droplets of two sets of aqueous solutions include the geometry of the microchannels, the capillary number, and the water fraction of the system. Glass capillaries could be coupled to the PDMS microchannels and droplets could be transferred into glass capillaries for long-term storage. The arrays of droplets have been applied to screen the conditions for protein crystallization with microbatch and vapor diffusion techniques.     

碾压混凝土在铜街子工程1号坝施工中的应用

铜街子1号坝系铜街子水电站主体工程的一部分,水电部第七工程局及成都水电勘测设计院在该坝进行了碾压混凝土施工原型试验研究。本文介绍了在铜街子工程条件下,该坝所采用的配合比、碾压工艺、机械配套和质量控制手段,为我国在其他工程上应用碾压混凝土这一先进施工方法提供了经验。     

Thermoelectric temperature control device for vapor pressure measurements

The static method of measuring equilibrium vapor pressure requires locating the sample at the coldest part of the apparatus to avoid errors due to evaporation and recondensation elsewhere. This paper describes a device that can hold the sample 1 K below the temperature of the surrounding air without a liquid bath. It comprises a pair of thermoelectric elements and two thermometers attached to an insulated aluminum block. The device can operate as high as 200?°C while controlling the sample with a precision of 0.02 K; below 110?°C, the precision is 2 mK. Also described is a method to measure the small temperature offset due to heat flow between the sample and the surrounding aluminum block. The uncertainty due to the offset is small compared to the 6 mK uncertainty due to the thermometer.     

Note: Solution NMR probe for the study of CO2 sequestration at elevated pressure and temperature

Nuclear magnetic resonance is widely employed in studies of chemical reactions and molecular motions at moderate pressure and temperature, but for CO(2) solutions under supercritical conditions encountered in geological or mineral sequestration (pressures to 150 atm and temperatures to 150 °C) a specialized variable-temperature probe is required. The critical component of such a probe is its pressure chamber, and our working design is presented along with examples of its use in (13)C NMR measurements of bicarbonate and dissolved CO(2) fractions as functions of time, following initial pressurization to 70 atm. Also shown are final, steady-state values of these fractions as functions of temperature from 50 to 125 °C at 70 atm.     

Structural study of titanium oxide films synthesized by ion beam-assisted deposition

The application of titanium dioxide (TiO(2)) films as surgical implant coatings for antibiotic attachment depends crucially on their available surface area and thus their surface morphology and crystallinity. Here, we report our fabrication of high Wenzel ratio TiO(2) films targeted to increase the film surface area using the ion beam-assisted deposition (IBAD) technique at high-deposition temperatures (approximately 610 degrees C). The modulation of the films' surface morphology was accomplished by varying the chemical identity of the concurrent ion beams bombarded on the films during the e-beam evaporation process. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to investigate the surface morphology of the as-deposited films. X-ray diffractometry (XRD) revealed that these nanocrystalline films primarily consist of anatase phase TiO(2). Wenzel ratio, the ratio of the actual surface area to the projected area, of IBAD films prepared with argon, oxygen, and nitrogen ion beams was measured to be 1.52, 1.31 and 1.49, respectively. The effect of the differences in chemical reactivity and ion size of these three type ion beams are discussed to explain the present results.     

The effect of floor slope on sub-maximal lifting capacity and technique

Inclined surfaces, where both the lifter and load are on the slope, may be encountered in a jobsite situation. The purpose of this study was to determine if facing up or down a sloped surface (10 degrees and 20 degrees ) would affect maximal acceptable weights of lift (MAWL) using a 10 min psychophysical approach with symmetric freestyle technique at 4 lifts/min. Seventeen healthy men and 18 women determined floor to knuckle height MAWL while facing uphill, downhill, and on a level surface. Motion capture was also performed to examine sagittal plane joint angles and foot placement relative to a milk crate. Slope did not alter MAWL (p>0.05) with the men lifting more than the women in every condition (p<0.001) (25 kg vs. 15 kg, respectively). Foot placement relative to the box was altered by slope such that both horizontal position behind and vertical position below the box increased as slope changed from the downhill to uphill conditions (both p<0.001). Forward torso lean as well as hip, knee, and ankle (plantar) flexion generally decreased as slope changed from the downhill to uphill conditions (all p<0.001). Torso and knee motion appeared to be protected compared to the other joints, changing the least. Though trends were the same in both sexes, interactions did exist in vertical foot position and hip angle (both p0.001). In conclusion, the body is highly adaptive to floor slope, maintaining MAWL at least in the short term. However, while slight technique differences exist between men and women, care should be taken by all when facing uphill due to the tendency to stand further from the load horizontally and when facing downhill due to increased torso lean.