One-step synthesis,characterization and oxidative desulfurization of 12-tungstophosphoric heteropolyanions immobilized on amino functionalized SBA-15

Keggin-type 12-tungstophosphoric [PW₁₂O₄₀]^3? heteropolyanions were successfully immobilized onto mesoporous material surface of SBA-15 functionalized using the (3-aminopropyl)triethoxysilane (APTES) synthesized by one-pot co-condensation method, also called one-step synthesis. The synthesized PW^?-NH₃⁺-SBA-15 catalyst was characterized by XRD, N₂ adsorption–desorption, FT-IR, TGA, SEM, TEM, EDS, XPS methods. The results indicated that ordered hexagonal mesostructure for SBA-15 support was still maintained after being functionalized with amine groups, while the specific surface area of SBA-15 was decreased. The active species of phosphotungstic acid H₃PW₁₂O₄₀ (HPW) retained its Keggin structure of the heteropolyanions on the amine-modified SBA-15. The PW^?–⁺H₃N–SBA–15 catalyst exhibited a high catalytic activity for oxidative desulfurization process of sulfur-containing model fuel. The dibenzothiophene (DBT) conversion of almost 100% was achieved with reaction conditions of 40?mg of catalyst dosage, 2?mL of hydrogen peroxide, 90?°C of reaction temperature, and 120?min of reaction time.     

Lysine 58 and histidine 66 at the C-terminal alpha-helix of monocyte chemoattractant protein-1 are essential for glycosaminoglycan binding

Monocytes rolling on the endothelial cell layer interact with monocyte chemoattractant protein-1 (MCP-1) that is tethered to the proteoglycans on the luminal side of the endothelial cells and consequently initiate adhesion of monocytes in the early phase of immune response. The amino acid residues in MCP-1 involved in tethering to the proteoglycans have not been elucidated. MCP-1 showed binding to [3H]heparin with a KD of 1.5 microM. We substituted lysine or histidine residues at the C-terminal end of MCP-1 with alanine residues and tested these mutants for their ability to bind heparin, heparan sulfate, hyaluronic acid, and chondroitin sulfate-C. Substitution of Lys-58 or His-66 drastically reduced glycosaminoglycan binding. Substitution of Lys-56 or deletion of the five amino acid residues at the C terminus, including Lys-75, did not alter the heparin binding ability, suggesting that the other lysine residues at the C terminus are not involved in glycosaminoglycan binding. MCP-1 and its mutants did not bind hyaluronic acid as strongly as the other subunits of the GAGs. Substitution of Lys-58 or His-66 by alanine that prevented glycosaminoglycan binding did not affect Ca2+ influx, receptor binding, or chemotactic activity elicited by the chemokine on monocytic THP-1 cells. Therefore, we conclude that the Lys-58 and His-66 residues in the C-terminal alpha-helix of MCP-1 are essential for glycosaminoglycan binding and probably for the binding to the endothelial surface proteoglycans.     

Recent advances in fire–structure analysis

One of the recommendations of the National Construction Safety Team (NCST) for the Federal Building and Fire Safety Investigation of the World Trade Center Disaster [NIST NCSTAR 1 Final report on the collapse of the World Trade Center Towers. NCST for the Federal Building and Fire Safety Investigation of the World Trade Center Disaster, National Institute of Standards and Technology, Gaithersburg, MD, September 2005] is to enhance the capability of available computational software to predict the effects of fires in buildings, for use in the design of fire protection systems and the analysis of building response to fires. Following this recommendation, this paper presents two new interfaces in fire–thermal–structural analysis. The first interface uses adiabatic surface temperatures to provide an efficient way of transferring thermal results from a fire simulation to a thermal analysis. It assigns these temperatures to surface elements of structural members based on proximity and directionality. The second interface allows the transfer of temperature results from a thermal analysis modeled with solid elements to a structural analysis modeled with beams and shells. The interface also allows the reverse, namely the geometric updating of the thermal model with deflections and strains obtained from the structural analysis. This last step is particularly useful in intense fires of long duration, where significant deflections and strains could cause damage to insulation and displace the structure to a different thermal regime. The procedures can be used for a variety of fire simulation, thermal, and structural analysis software.     

Control of milk pH reduces biofilm formation of Bacillus licheniformis and Lactobacillus paracasei on stainless steel

Microbial biofilms present in dairy farms may contaminate milk during milk harvest and transfer diseases from the environment to cows. In order to reduce biofilm formation with respect to the role of pH, a study involving the control of milk pH during long-term biofilm formation of Bacillus licheniformis NBRC 12195 and Lactobacillus paracasei subsp. paracasei NBRC 15889 on stainless steel coupons in different dilutions of skim milk (0.1%, 1.0% and 5.0%) was conducted. During long incubation at 30 °C, pH decreased due to bacterial development in unadjusted samples. In pH-adjusted samples, pH was kept at around 7.0 by the addition of sterile sodium hydroxide. Biofilms formed on stainless steel coupons were daily stained by 0.1% Crystal Violet solution and assessed by the evaluation of optical density. The bacterial count of the suspensions showed that the control of pH enhanced the growth of bacteria in free-floating form. In contrast, optical densities of biofilms formed in the pH-adjusted samples were significantly lower than in the pH-unadjusted samples in all of three skim milk dilutions. Comparison of maximum OD values of adhered cells at different nutrient levels also implicated that for both tested strains, thicker biofilms were formed in milk dilutions at higher nutrient levels. These results suggested that, control of milk pH and milk residue level could significantly reduce biofilm formation of the tested bacteria.     

Analyzing the ranking method for L–R fuzzy numbers based on deviation degree

Ranking fuzzy numbers based on their left and right deviation degree (L–R deviation degree) has attracted the attention of many scholars recently, yet most of their ranking methods have two systematic shortcomings that are usually ignored. This paper addresses these shortcomings and proves them through mathematical proofs instead of providing counter-examples. Applying our analyses will help other authors avoid some common errors when building their own ranking index functions. We use Asady’s ranking index function (2010) as an example when we present our arguments and proofs and provide fully detailed analyses of two of the ranking index functions herein. Based on these analyses, an algorithm for detecting inconsistencies in ranking results is proposed, and numerical examples are given to illustrate our arguments.     

Constraint of Oxygen Fugacity During Field-Assisted Sintering: TiO2 as a Test Case

Field-assisted sintering exposes samples in a graphite die to reducing conditions. Using TiO₂ as a test case, this work shows that internal redox equlibria in the sample, rather than the graphite–CO–O₂ equilibrium, appear to control the oxygen fugacity. Samples sintered at 1160°C for 20 min are homogeneous in oxygen content and have an average composition of TiO_1.983±0.001. The oxygen fugacity during these sintering experiments is calculated to be about 10⁻¹⁶ atm, which is higher than the value obtained from thermodynamic equilibrium of graphite–CO–O₂ at the given temperature. The oxygen fugacity is similar to that for the quasi-two-phase region, or hysteresis loop, representing the coexistence of reduced rutile with random crystallographic shear (CS) planes and the first ordered CS phase.     

Ascorbic acid,glutathione and synthetic antioxidants prevent the oxidation of vitamin E in platelets

An earlier report from this laboratory showed that tocopherol in human platelets is oxidized when the platelets are incubatedin vitro in Tyrode medium with arachidonate (or other oxidants). Arachidonate is a more potent oxidizing agent in 50 mM potassium phosphate buffer at pH 7.4 with 0.1 mM ethylenediaminetetraacetic acid (EDTA) than in Tyrode medium. Forty to fifty percent of total platelet tocopherol was oxidized upon incubation with 40–50 μM arachidonate in the phosphate-buffered medium. The tocopherol oxidation took place within 15 min after the addition of arachidonate. Preincubation of platelets with ascorbate blocked the oxidation of tocopherol. This is one of the first directin vitro demonstrations of the vitamin E-sparing action of vitamin C in media containing biological cellular material. Other compounds which blocked the oxidation of platelet tocopherol were ascorbyl palmitate, propyl gallate, butylated hydroxytoluene, hydroquinone and glutathione. If ascorbate or glutathione was added after the tocopherol was oxidized to the quinone there was no reversal of the oxidation.     

Estimation and Compensation of Gravity and Friction Forces for Robot Arms: Theory and Experiments

This paper considers the estimation and compensation of the unknown gravity force and static friction for robot motion control. Utilizing the stability feature of PD set-point control, the estimates of gravity-related parameters and static friction can be solved from two steady state equations obtained by stopping robots at two nonsingular positions. The estimates obtained can then be used to eliminate the position error. Under a mild assumption that the mass center of each robot link is distributed on a straight line connecting two adjacent joints, the gravity force regression matrix becomes upper-triangle which can significantly simplify the algorithm. The positive experimental result obtained for practical verification is also presented.     

Control of marine riser end angles by position mooring

For safe drilling and work-over operations on floating platform, one objective is to minimize the rigid riser angles at the well-head and at the top joint. One way to achieve this is to control the vessel’s position. For shallow water, drilling operations are normally carried out using a moored vessel. In this paper, a system consisting of a vessel, mooring lines and a drilling riser was mathematically modelled. The strategy was to control the vessel’s position by changing the tensions in the mooring lines to ensure that the riser end angles are within safe limits. Numerical simulations and experiments of a moored vessel were performed to illustrate the feasibility of the proposed control strategy.