Attribute dependency functions considering data efficiency

Pawlak’s attribute dependency degree model is applicable to feature selection in pattern recognition. However, the dependency degrees given by the model are often inadequately computed as a result of the indiscernibility relation. This paper discusses an improvement to Pawlak’s model and presents a new attribute dependency function. The proposed model is based on decision-relative discernibility matrices and measures how many times condition attributes are used to determine the decision value by referring to the matrix. The proposed dependency degree is computed by considering the two cases that two decision values are equal or unequal. A feature of the proposed model is that attribute dependency degrees have significant properties related to those of Armstrong’s axioms. An advantage of the proposed model is that data efficiency is considered in the computation of dependency degrees. It is shown through examples that the proposed model is able to compute dependency degrees more strictly than Pawlak’s model.     

Synthesis and spectroscopic investigation of trifluoroethoxy-coated phthalocyanine linked with fullerene

Synthesis and spectroscopic investigation of trifluoroethoxy-coated phthalocyanine-fullerene dyad 2 has been described. While nonfluorinated phthalocyanine-fullerene dyad 1 showed an efficient property of intramolecular photoinduced electron transfer, dyad 2, regardless of its covalently linked dyad system, appears not to show any electronic communication between fullerene and phthalocyanine. This observation is presumably due to the strong electron withdrawing nature of 12 trifluoroethoxy groups; fluorine leads phthalocyanine to become an acceptor whose electronic accepting property is equivalent to that of fullerene. This is a unique example that fluorine can terminate electronic communication in the covalently fullerene-phthalocyanine dyad system.     

Redox Denaturation of Proteins: Electrochemical Treatment of Egg Plasma

Although acid/base reactions are used widely to denature proteins during food processing, the application of reduction/oxidation (redox) reactions are relatively rare in this field. Herein, we demonstrate a “redox denaturation” of proteins, using egg plasma as a model. Electrochemical treatment of egg plasma in the presence of iodide ion (I^?) selectively induced intramolecular disulfide bond formations, resulting in a different type of denaturation than that achieved via heat treatment. The reaction mechanism was examined through electrochemical analysis using cyclic voltammetry. Although the involvement of hypervalent iodine (“I⁺”) cannot be ruled out, molecular iodine (I₂) generated at the surface of anode is the most likely oxidizing agent that formed the disulfide bonds. We believe that the redox denaturation of proteins described herein would be a promising approach in food processing and can find practical applications in this field.     

2‐Phenylquinoline–Sugar Hybrids as Photoswitchable α‐Glucosidase Inhibitors

Purpose‐designed 2‐phenylquinoline (PQ)‐sugar hybrids 1 and 2 were synthesized and evaluated for their photodegradation activities against an α‐glucosidase target. The results indicated that PQ‐mannose hybrid 2 selectively and effectively photodegraded α‐glucosidase and significantly inhibited its enzymatic activity upon irradiation with long‐wavelength UV light in the absence of any additives under neutral and aqueous conditions. Furthermore, 2 selectively and effectively inhibited α‐glucosidase activity only with photo‐irradiation even in complex cell lysate.     

Efficient preparation of dichloromethyl alkyl ethers and their application in the formylation of aromatic compounds: Scope and limitations

Practical preparations of dichloromethyl alkyl ethers are described, based on the reaction of alkyl formates with oxalyl chloride in the presence of N-methylformanilide. The method involves a simple procedure that does not require the use of harmful reagents. Dichloromethyl propyl and dichloromethyl butyl ethers represent secure synthetic equivalents to dichloromethyl methyl ether. Formylations of both electron-deficient and electron-rich aromatics with these dichloromethyl alkyl ethers in the presence of AlCl₃, FeCl₃, or TiCl₄ have been systematically investigated. A plausible mechanism of formylation is discussed.     

Alkyllithium Compounds Bearing Electrophilic Functional Groups: A Flash Chemistry Approach

Flash chemistry based on flow microreactor systems allowed alkyllithiums bearing electrophilic functional groups to be successfully generated and used for subsequent reactions. The series of reactions with high reactivity was achieved by extremely accurate control over residence time in a controlled and selective manner.     

Silica coating of Co–Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone)

This article describes a method for silica coating of Co–Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone) (PVP) as a stabilizer. The Co–Pt nanoparticles were prepared in an aqueous solution at 25–80 °C from CoCl₂ (3.0 × 10⁻⁴ M), H₂PtCl₆ (3.0 × 10⁻⁴ M), PVP (0–10 g/L), and NaBH₄ (4.8 × 10⁻³–2.4 × 10⁻² M). The silica coating was performed for the Co–Pt nanoparticle colloid containing the PVP ([Co] = [Pt] = 3.0 × 10⁻⁵ M) at 25 °C in (1/4) (v/v) water/ethanol solution with tetraethoxyorthosilicate (TEOS) (7.2 × 10⁻⁵–7.2 × 10⁻³ M) and ammonia (0.1–1.0 M). Silica particles, which had an average size of 43 nm and contained multiple cores of Co–Pt nanoparticles with a size of ca. 8 nm, were produced at 1.4 × 10⁻³ M TEOS and 0.5 M ammonia after the preparation of Co–Pt nanoparticles at 80 °C, 5 g/L PVP, and 2.4 × 10⁻² M NaBH₄. Their core particles were fcc Co–Pt alloy crystallites. Their saturation magnetization was 2.0-emu/g sample, and their coercive field was 12 Oe.     

Whereabouts of missing atoms in a laser-injected Si: Part 1

In a stealth dicing of Si wafers, voids are formed in laser-induced modified volumes (LIMVs). Most of the voids are free from apparent defects such as dislocations and cracks. Needless to say, in what will become a void (pre-void) upon laser injection, Si atoms are present prior to the laser injection. The critical issue is where these missing atoms are after the laser injection. Two obvious possibilities are that (1) they remain inside the Si wafer as interstitials (I’s) or (2) these I’s reach the surface of the wafer to disappear. If (1) is the case, I’s are to coagulate to form dislocation loops of I-type upon post laser-injection annealing. However, it has been shown that this is not the case. In order to see whether (2) is the case, surfaces of a laser-injected Si wafer were studied by a scanning electron microscope in detail. No evidence of I’s having reached the surfaces was obtained.     

Versatile Synthesis of Polyaniline/Pd Nanoparticles and Catalytic Application

Polyaniline/Pd nanoparticles were synthesized through two approaches. “Direct reduction approach” was revealed to be a simple method to prepare small (2–7 nm) and dispersed polyaniline/Pd nanoparticles via reduction with sodium borohydride. On the other hand, “template approach” was developed to provide a versatile route to small and well-dispersed nanoparticles (1–4 nm, average diameter = 2.4 nm) with high Pd density due to pre-organization of Pd(II) species on polyaniline into the corresponding d,π-conjugated complex. Thus-obtained nanoparticles worked as an efficient redox catalyst for oxidative coupling reaction of 2,6-di-t-butylphenol.