The influence of polymer morphology on the performance of molecularly imprinted polymers

This is the first in-depth study examining the effect of morphology on the performance of 2-aminopyridine (2-apy) imprinted polymers. A series of polymers were prepared by varying the amount of crosslinking monomer (EGDMA) whilst the other polymer components remained constant. Physical characterisation was carried out using conventional techniques, such as nitrogen sorption porosimetry and solvent swelling studies. The use of a novel thermal desorption GC-MS technique suggested higher levels of polymer degradation with prolonged exposure to elevated temperatures for those polymers formed with lower amounts of EGDMA. The thermal desorption GC-MS profiles obtained correlated with the physical characteristics of the polymers, where higher levels of polymer bleed was found to occur with larger average pore diameters. Polymer physical characteristics were also found to correlate with the binding parameters (number of binding sites and polymer-template association energy) obtained from the Langmuir-Freundlich Isotherm (L-FI) and affinity distribution spectra (AD). The flexibility of the polymers formed from lower amounts of EGDMA combined the swelling effect of the solvents on the polymers resulted in an increase in affinity, which was both specific and non-specific in nature.     

Reductive debromination of polybrominated diphenyl ethers in anaerobic sediment and a biomimetic system

Because of the bioaccumulation of penta- and tetrapolybrominated diphenyl ether (PBDE) flame retardants in biota,the environmental biotransformation of decabromodiphenyl ether (BDE-209) is of interest. BDE-209 accounts for more than 80% by mass of PBDE production and is the dominant PBDE in sediments. Most sediments are anaerobic and reports of microbial reductive dehalogenation of hydrophobic persistent organohalogen pollutants are numerous. Reductive debromination of BDE-209 in the environment could provide a significant source of lesser-brominated PBDEs to biota. Moreover, a recent study showed that BDE-209 debrominates in sewage sludge, and another demonstrated that some halorespiring bacteria will debrominate BDE-209. To determine whether reductive debromination of BDE-209 occurs in sediments, parallel experiments were conducted using anaerobic sediment microcosms and a cosolvent-enhanced biomimetic system. In the biomimetic system, reductive debromination occurred at rates corresponding to bromine substitution levels with a BDE-209 half-life of only 18 s compared with a halflife of almost 60 days for 2,2',4,4'-tetrabromodiphenyl ether. In sediment, the measured debromination half-life of BDE-209 was well over a decade and was in good agreement with the predicted value obtained from the biomimetic experiment. Product congeners were predominantly double para-substituted. BDE-209 debrominated in sediment with a corresponding increase in nona-, octa-, hepta-, and hexa-PBDEs. Nine new PBDE congeners appeared in sediment from reductive debromination. Given the very large BDE-209 burden already in sediments globally, it is important to determine whether this transformation is a significant source of lesser-brominated PBDEs to the environment.     

A computational study on optimal design for organic tandem solar cells

A new model is developed by combining the optical model and the drift-diffusion model to optimize the thicknesses of active layers of individual sub-cells for high performance of organic tandem solar cell. When the photovoltaic properties of tandem organic solar cells based on poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta (2,1-b;3,4-b′) dithiophene)-alt-4,7-(2,1,3-benzo-thiadiazole))/(6,6)-phenyl C71-butyric acid methyl ester and poly(3-hexylthiophene)/(6,6)-phenyl C61-butyric acid methyl ester are calculated as functions of thicknesses of individual sub-cells using the new model, it is found that the optimum thickness pair of active layers is 150 and 120 nm for the front and back sub-cell, respectively. Comparison of simulation with experiment reveals that the simulated results are very consistent with experimental ones.     

Numerical study for laminar wavy motions of liquid film flow on vertical wall

Film flows are classified into non-wavy laminar, wavy laminar and turbulence along the Reynolds number or the flow stability. Since the wavy motions of the film flows are so intricate and nonlinear, the studies have largely been dependent upon the experimental way. The numerical approaches have been limited on the non-wavy flow regime. To track the free surface position, various numerical techniques such as the VOF (Volume of Fluids), the MAC (Marker and Cell) and the moving grid have been adopted. However those were for a more accurate estimation of the average film thickness and not for capturing the wavy motion. Because the wavy motion highly affects the heat transfer in the film flow, the profound concern for the wavy motion is significant. In this study, the wavy motions of the laminar wavy film flow with the Reynolds number 200–1000 are successfully found by the VOF and PLIC (Piecewise Linear Interface Calculation) method. The numerical results, including the average film thickness, and the wave’s amplitude, frequency and velocity, are compared with the experimental results.     

米氏旋回基本原理及其在陆相湖盆分析中的应用前景

米氏旋回是指峰值时间跨度为20－500ka,日地天轨道参数的周期性变化,以及由此产生的气候和沉积地层的旋回性变化。米氏旋回主要通过改变地球表面的太阳辐射能对气候变化进行控制,并对沉积作用产生重要的影响,通过沉积地层观测数据的时序分析可以重建米氏旋回,对地层的成因和过程进行研究。米氏旋回代表地层学和古气候学研究的前沿课题,不仅在深海沉积物的研究中得到了广泛应用,对陆相含油气盆地地层分析和油气储集层的预测也都具有重要意义。     

DEVELOPMENT AND APPLICATION OF INTERFERENCE TESTING DATA ANALYSIS MODEL FOR DUAL-POROSITY SYSTEM USING BOUNDARY ELEMENT METHOD

The main purpose of this paper is to develop a boundary element model in order to analyze the data from naturally fractured reservoirs with complex-shaped boundary. The model employs a boundary element method with free-space Green's function as a weighting function that makes it possible to handle multi-well system with geometrically complex boundary. The developed model has been validated by using the published actual field data for naturally fractured reservoir. The result shows that the model is capable of describing the transient pressure behavior representing the characteristics of naturally fractured reservoirs. The calculated permeability agrees well with the published result. In case of multi-well homogeneous reservoir system with complex geometry, both the transient state data and the data including boundary effect have been analyzed. The calculated permeabilities in each case were computed identically. This represents that the model can be effectively used for the analysis of data with boundary effect. In order to investigate the field applicability of the model, the actual field interference testing data performed in the Maljamar reservoir, New Mexico, USA were used. The relative fracture storage capacity and inter-porosity flow parameter were computed as 1.0 and 0.0, respectively. This implies that porosity and permeability of matrix are extremely low compared with those of fracture, and the flow occurs only through the secondary porosity system such as fracture network.     

Steady-flow characteristics and its influence on spray for direct injection diesel engine

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of Dl (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70ΰ and 90ΰ. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.     

Effects of mineral oil coating on internal quality of chicken eggs under refrigerated storage

The selected internal qualities (weight loss, Haugh unit, yolk index, and albumen pH) of noncoated and mineral oil‐coated chicken eggs during 15 weeks of storage at 4 °C and/or during 5 weeks of storage at 25 °C were evaluated. Results indicated that, without refrigeration, the noncoated and mineral oil‐coated eggs rapidly changed from AA to C and B grades as measured by Haugh unit, respectively, after 5 weeks of storage. However, the AA quality of the noncoated eggs could be maintained under refrigerated storage (4 °C) for at least 5 weeks. The mineral oil coating and refrigerated storage (4 °C) synergistically minimised weight loss and preserved the albumen and yolk qualities of chicken eggs during a long‐term storage. At 4 °C, the mineral oil‐coated eggs preserved the initial AA grade for at least 15 weeks with l.19% weight loss.     

A study of through-thickness texture gradients in rolled sheets

A method to simulate shear effects and through-thickness texture gradients in rolled sheet materials is introduced. The strain history during a rolling pass is idealized by superimposing a sine-shaped evolution of the ₁₃ shear component to a plane-strain state. These generic strain histories are enforced in a visco-plastic self-consistent (VPSC) polycrystal deformation model to simulate texture evolution as a function of through-thickness position. The VPSC scheme is deemed superior to a full constraints (FC) or relaxed constraints (RC) approach, because it allows one to fully prescribe diagonal and shear-strain-rate components while still accounting for grain-shape effects. The idealized strain states are validated by comparison with deformation histories obtained through finite-element method (FEM) calculations. The through-thickness texture gradients are accounted for by introducing a relative variation of the sine-shaped ₁₃ shear with respect to the plane-strain component. The simulation results are validated, in turn, by comparison with typical examples of through-thickness texture gradients observed experimentally in rolled plates and in sheets of fcc and bcc materials.