Optimal layout of additional facilities for minimization of domino effects based on worst-case scenarios

Accidents involving domino effects are more serious than other type of accidents. Although there have been studies on such accidents, it is still difficult to examine the actual factors and causes since the domino effect is influenced nonlinearly by factors involving flame, overpressure, and flying objects. We considered the case of adding new facilities to an existing system in a given site. The layout of new facilities suggests positions that minimize the domino effects, based on nonlinear optimization taking domino factors into account. We quantitatively calculated the domino risk of each facility through the concept of combined domino factors (flame, overpressure, and missile). Also, we identified variations of domino damage extent of the target system through comparison of the impacts of domino effect when additional facilities were installed. Simulated annealing was adopted for searching optimal positions. As a case study, we applied the proposed method to the case of adding DME storage tanks in the existing LPG charging facilities. The presented framework of the quantitative assessment of domino risk and safety standard for the layout of additional facilities would be useful for proper layout design for improved accident prevention.     

An efficient microwave-assisted Suzuki reaction using Pd/MCM-41 and Pd/SBA-15 as catalysts in solvent-free condition

Palladium catalysts, Pd/MCM-41 and Pd/SBA-15 were prepared by impregnation of an aqueous solution of [Pd(NH₃)₄]Cl₂ on MCM-41 and SBA-15. Palladium contents of Pd/MCM-41 and Pd/SBA-15 are 8.4% and 8.7%, respectively. It has been shown that these catalysts are very suitable to microwave-assisted Suzuki reactions under solvent-free condition. It is also found that the base additives for this reaction are K₂CO₃, Cs₂CO₃ or CsF. Thus, phenylboronic acid and phenyl iodide with Pd/MCM-41 produce biphenyl by microwave irradiation for 10 min in 97.4% yield. Phenyl bromide, instead of phenyl iodide, also proceeds the reaction with phenylboronic acid using Pd/MCM-41 or Pd/SBA-15 yielding biphenyl by microwave irradiation for 10 min in excellent yield. Whereas the reaction of phenyl chloride with phenylboronic acid gives poor yield in same condition. Various aryl iodides and aryl bromides are tested. In this paper our recent results of microwave-assisted Suzuki reaction using Pd/MCM-41 and Pd/SBA-15 under solvent-free condition are described.     

Prunella vulgaris Suppresses HG-Induced Vascular Inflammation via Nrf2/HO-1/eNOS Activation

Vascular inflammation is an important factor which can promote diabetic complications. In this study, the inhibitory effects of aqueous extract from Prunella vulgaris (APV) on high glucose (HG)-induced expression of cell adhesion molecules in human umbilical vein endothelial cells (HUVEC) are reported. APV decreased HG-induced expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. APV also dose-dependently inhibited HG-induced adhesion of HL-60 monocytic cells. APV suppressed p65 NF-κB activation in HG-treated cells. APV significantly inhibited the formation of intracellular reactive oxygen species (ROS). HG-stimulated HUVEC secreted gelatinases, however, APV inhibited it. APV induced Akt phosphorylation as well as activation of heme oxygenase-1 (HO-1), eNOS, and nuclear factor E2-related factor 2 (Nrf2), which may protect vascular inflammation caused by HG. In conclusion, APV exerts anti-inflammatory effect via inhibition of ROS/NF-κB pathway by inducing HO-1 and eNOS expression mediated by Nrf2, thereby suggesting that Prunella vulgaris may be a possible therapeutic approach to the inhibition of diabetic vascular diseases.     

CO2 laser-assisted preparation of transparent Eu2Ti2O7 thin films

We present a laser-assisted preparation of transparent europium-titanate Eu₂Ti₂O₇ thin films with tailored structural and optical properties. We have evaluated the effects of the irradiation time on the structural and the optical properties of the films. This approach allows the preparation of nanocrystalline crack-free films and micro patterns. The amorphous thin films were prepared by a sol-gel method. The films were annealed by a CO₂ laser beam for various time intervals. The laser irradiation induced a crystallization process that resulted in the formation of Eu₂Ti₂O₇ nanocrystals. The nanocrystals regularly grew with increasing irradiation time reaching the size from 25?nm to 45?nm. A film of a thickness 480?nm exhibited an optical transmission of 91.9% that is close to the maximal theoretical limit. The film's refractive index at 632?nm was 2.26. A micrometric pattern was prepared by a direct laser writing followed by a wet chemical etching. Feasibility of the demonstrated approach, together with the high film's quality, and europium-titanate chemical resistivity open up many opportunities for advanced applications. The approach can be used for a preparation of protective coatings and integrated photonic devices such as planar optical waveguides and couplers.     

Determination of load carrying ability of chemical films developed in sliding point contact

It has already been known for many years that the use of some extreme-pressure (EP), antiwear or friction modifier (FM) additives in mineral oils can produce different kind of boundary or chemical reaction films on sliding contact surfaces of some kinds of steel in boundary lubrication conditions. Using a sliding ball-on-disc configuration lubricated with some kinds of EP or FM, the wear scars on the balls can always reach the same limit size at a specified applied load and sliding velocity. From the fact that the limit sizes of wear scars decrease as sliding speed is increased or applied load is decreased, the load carrying ability of a chemical film can be obtained by extrapolating the data to the condition of zero sliding speed and is so defined that if the contact pressure is greater than this load carrying ability, the contact surfaces will continuously be worn; if the contact pressure is smaller than it, no more wear will occur on the surfaces. Based on this load carrying ability, the hydrodynamic effect of sliding pairs can also be identified. Therefore, the limit size of wear scar at specified sliding speed and applied load can also be predicted in a mixed lubrication condition.     

Swelling equilibria of polymeric hydrogels containing poly(acrylamidesodiumallylsulfonate-acrylic acid)

The superabsorbent poly(AM-SAS-AA)s were synthesized to improve the water absorption capacities in comparison with the poly(AM-SAS) by an aqueous solution polymerization method from acrylamide (AM), sodium allylsulfonate (SAS), and acrylic acid (AA). The reaction conditions were controlled by varying the AA concentrations and fixing other agent concentrations to obtain the optimal superabsorbent poly(AM-SAS-AA). The poly(AM-SAS-AA) showed maximal absorption capacity at 0.3 mol/L among AA concentrations from 0.053mol/L to 0.4 mol/L. The water absorption capacities of poly(AM-SAS-AA)s prepared at the optimal reaction condition were measured within the temperature ranges from 298.15K to 318.15K. Those experimental data were used to describe the effect factors on absorption capacities and swelling equilibria data among those data were correlated with the swelling models to estimate the interchange energy parameters. Each swelling models combined with group contribution models (UNIFAC, ASOG) was introduced to calculate the swelling equilibria of water(1)/poly(AM-SAS-AA)(2) systems. The swelling behaviors could be described by the estimated parameters, and the calculated values agreed well with the experimental data.     

Effect of combining boron nitride with fluoroelastomer on the melt fracture of HDPE in extrusion blow molding

Boron nitride (BN) is a new polymer processing aid which not only eliminates surface melt fracture in the extrusion of molten polymers, but also postpones the critical shear rate for the onset of gross melt fracture to significantly higher values that depend on resin type and additive concentration. In this work, the influence of BN as a polymer processing additive is first examined in the extrusion blow molding of high‐density polyethylene (HDPE) resins in order to evaluate its usefulness and performance in operations other than continuous extrusion. The equipment used includes both a Battenfeld/Fisher 50‐mm extrusion blow molding machine and a parallel‐plate rheometer. Two types of HDPE, which are blended with boron nitride at various concentration levels, are tested accordingly. It is found that the degree of BN dispersion, characteristics of the HDPE resins, extrusion temperature, and induction time play an important role in eliminating melt fracture. Finally, the influence of combining BN with fluoroelastomer, as an enhanced and potentially better processing aid on the melt fracture of a third HDPE is examined. It is found that such a combination is a superior processing aid that allows extrusion blow molding at very high shear rates.     

Evaluation of pathways for washing soluble solids

Filter cake washing is a purification method for particulate products in liquids. This process is mostly one step of a sequence in a solid–liquid separation process. For soluble products not only the mechanical transport mechanisms in washing but also the dissolution process of the product must be considered in order to describe the washing process appropriately. An unconsidered dissolution may cause problems and often severe product loss depending on the material properties. This paper presents several methods of soluble solids washing including filter cake washing by pressure and centrifugal forces as well as moving bed washing. The advantages and drawbacks of each method are discussed to evaluate the suitability of its technical application.