Parameter identification of river current and diffusion by reduced Kalman filter finite element method

The objective of this study is to propose a parameter identification of a river current and diffusion coefficients by using the reduced Kalman filter finite element method, which has been previously presented and now extended by the authors. For comparison, the estimation computations of velocity, water elevation, and chemical oxygen demand (COD) concentration are carried out on the basis of nonlinear shallow water flow and compared with the observations carried out at the Teganuma river in Japan. A marked discrepancy in COD concentration is found between the computed and observed results. The correlation factor between the computed and observed results is 0.51. To reduce the discrepancy, the authors believe that the diffusion coefficients should be identified. Assuming that the diffusion coefficient is constant in the entire domain and over the entire total duration, satisfactory results were not obtained. Thus, the computational domain is divided into four subdomains according to the water depth. Assuming that the diffusion coefficients are constant in each subdomain, the identification is carried out. Relatively good, albeit unsatisfactory, results are obtained. The discrepancy between the computed and observed COD concentration has special features. In some time zones, the computed results are larger whereas in other time zones, they are smaller than the observed results. To compensate this discrepancy, we assumed that the diffusion coefficient is a function of COD concentration. The correlation factor is improved to be 0.73. The identified diffusion coefficients are time functions that change cyclically with a period of 24 h. This fact suggests that biological phenomenas occurred in the river. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of 2‐Deoxy‐2‐thiophenylglucosyl Azides through 1,2 Thio Migration of Thiophenyl Mannosides

2‐Deoxy‐2‐thio glucosyl azides bearing or not bearing an azido group at the 6‐position can be conveniently obtained through a 1,2‐thio migration from thiophenyl mannoside derivatives.     

Stable heterocumulene monomer in water; Synthesis and polymerization of (meth)acrylates having an isothiocyanate structure

Novel methacrylate and acrylate monomers having an isothiocyanate structure, 2‐isothiocyanatoethyl methacrylate (ITEMA) and 2‐isothiocyanatoethyl acrylate (ITEA), were synthesized, and their radical polymerizations were examined, respectively. ITEMA and ITEA were synthesized by addition of carbon disulfide to 2‐aminoethyl methacryrate or 2‐aminoethyl acrylate, followed by treatment with ethyl chloroformate. Radical polymerizations of the obtained monomers ( ITEMA , ITEA ) were carried out methyl ethyl ketone using 2,2'‐azobisisobutyronitrile (AIBN) as an initiator to obtain the corresponding polymers. The glass transition temperatures of the poly‐ITEMA and poly‐ITEA were determined to be 55 and 2 °C by differential scanning calorimetry, respectively. The 5 wt % decomposition temperatures of the poly‐ITEMA and poly‐ITEA were determined to be 277 and 269 °C by thermogravimetric analysis, respectively. Isothiocyanato groups in the monomers did not react with water in acetone solution at 60 °C for 24 h to be tolerable to water. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4522–4529     

Asymmetric Synthesis of Heptacosane-6,8-Diols Induced by Chiral Sulfoxides

The asymmetric synthesis of (6S,8R)-, (6S,8S)-, (6R,8S)- and (6R,8R)-heptacosane-6,8-diols from (2S)-, (2R)-1-[(R)-p-tolylsulfinyl]-2-heptanols and 1-icosanal is described.     

All-atom molecular simulation study of cellulose acetate: amorphous structure and the dissolution of small molecule

All-atom analysis was conducted for cellulose acetate (CA) using molecular dynamics simulation. The intermolecular interactions were elucidated at the amorphous state with degrees of acetyl substitution (DS) of 2, 2.5, and 3, and the energetics of dissolution was treated for H₂O, CO₂, and CH₄. It was observed for the CA amorphous that DS strongly affects the hydrogen bonding among the hydroxy groups of CA and that the short-range packing of pyranose rings becomes tighter with acetylation. The free energy of dissolution was computed by the energy-representation method of solvation. The dissolution into CA was more favorable in the order of H₂O?>?CO₂?>?CH₄, and the DS dependence of the dissolution free energy was evident only for H₂O between DS?=?2 and 2.5. The roles of the intermolecular interaction components were further addressed. It was seen that the electrostatic component brings the DS dependence of the dissolution free energy for H₂O as well as the difference in the affinity to CA between CO₂ and CH₄. The van der Waals component was still dominant for the nonpolar CO₂ and CH₄, and the summed contribution to it from the acetyl and main-chain groups of CA was weakly dependent on DS. The connection of the dissolution energetics with the underlying structures is also discussed.

Graphical abstract