Application of the alternating direction method of multipliers to separable convex programming problems

This paper presents a decomposition algorithm for solving convex programming problems with separable structure. The algorithm is obtained through application of the alternating direction method of multipliers to the dual of the convex programming problem to be solved. In particular, the algorithm reduces to the ordinary method of multipliers when the problem is regarded as nonseparable. Under the assumption that both primal and dual problems have at least one solution and the solution set of the primal problem is bounded, global convergence of the algorithm is established.     

Site-specific valence-band X-ray photoelectron spectra of a SrTiO3 single-crystal by X-ray standing wave technique

Site-specific valence-band X-ray photoelectron spectra of SrTiO₃ (111) were successfully obtained by using X-ray standing wave technique. Contributions of the Ti and SrO₃ derived states to the valence-band spectra were clearly separated. The spectra provided not only site-specific but also bulk-sensitive information on the SrTiO₃ crystal because of the use of a high-energy synchrotron X-ray source (hν=4750 eV) for photoelectron excitation with the large escape depth. The electronic structures calculated by the DV-Xα method using a (Sr₈Ti₂₇O₁₀₈)⁹²⁻ cluster model well reproduced the observed structures in the valence-band spectra. The partial density of states of both Ti and Sr ions in SrTiO₃ were mainly distributed over the bottom of the valence-band to produce the covalent bonding with O ions.     

Photoinduced one-electron reduction of MV2+ in titania nanosheets using porphyrin in mesoporous silica thin films

Composite films of a meso-(tetramethylpyridinium)porphyrin (TMPyP) hybrid incorporated in mesoporous silica (MPS) and cast on a methyl viologen (MV2+)/titania nanosheet hybrid were synthesized and a light-induced charge separation between the two could be observed. These composite thin films were able to initiate a one-electron reduction of the MV2+ ions accompanied by the simultaneous decomposition of the TMPyP organic dye within the mesoporous silica channels.     

Evaluation of copper(II)-binding ability of humic acids in peat using sulphopropyl-Sephadex C-25 cation exchanger

A method for the determination of copper(II) complexes with humic acids was developed by batch operation with the cation exchanger sulphopropyl-Sephadex C-25 (C-25). The copper-binding ability (conditional stability constants and copper-complexing capacities) of humic acids which were extracted from peat in Hokkaido was evaluated. A solution containing copper(II) ions and humic acids was shaken with the C-25 exchanger. The copper-humic acid complexes remained in the supernatant and the uncomplexed free copper ion was retained on the C-25. The copper-humic acid complexes were determined by flame atomic absorption spectrometry. The copper-binding ability of nitrilotriacetic acid (NTA) as a model ligand was similarly determined with a Scatchard plot. The conditional stability constant obtained at pH 4.5 was in good agreement with the reported value. The copper-binding abilities of the humic acids from peat were estimated using a Scatchard plot adopting a two-site model. The functional groups in the humic acids which contribute to the complexation with copper were investigated by conductimetric and pH titration, and the relationship between the copper-binding sites and functional groups in the humic acids was investigated.     

Cyclic isothioureido compounds. II. Reaction of trans-3a,4,5,9b-tetrahydronaphth[1,2-d]-imidazoline-2-thiones with α-bromoketones

The reaction of trans-3a,4,5,9b-tetrahydronaphth[1,2-d]imidazoline-2-thiones ( 8 ) with α-bromoketones gave, depending upon the structure of the α-bromoketones, reaction solvent and reaction temperature, the hydrobromides of tetrahydronaphth[1,2-d]imidazolin-2-ylthiomethyl ketone ( 10 ), hexahydro-8-hydroxynaphth[1′,2′:4,5]imidazo[2,1-b]thiazoles ( 5, 11, 19 and 20 ) or tetrahydronaphth[1′,2′:4,5]imidazo[2,1-b]-thiazoles ( 12 and 16 ). Structural determinations based on ir and nmr spectroscopies are discussed.     

Synthesis and characterization of polyester dendrimers from acetoacetate and acrylate

New aliphatic polyester-type dendrimers were synthesized using a new AB2-type building block 3, prepared from benzyl acetoacetate and 2 equiv of tert-butyl acrylate by acetoacetic acid ester synthesis. The reiterative [deprotection by HCO2H, then EDCI/DMAP coupling] sequence using divergent growth method gave [G1]-4tBu-[G5]-64tBu dendrimers. 13C NMR relaxation time (T1) measurements on the carboxy carbons show that the extended chain conformations are predominant in CDCl3. [structure: see text]