Decomposition of Log Crepant Birational Morphisms between Log Terminal Surfaces

We prove that every log crepant birational morphism between log terminal surfaces can be decomposed into log flopping type divisorial contraction morphisms and log blowdowns. Repeating these two kinds of contractions, we reach a minimal log minimal surface from any log minimal surface.     

Condensed Pyridazines. Part I. Synthesis of 2-Oxo-2H-pyrano[2,3-D]-pyridazine and 2-Oxo-2H-pyrano[2,3-c] pyridazine

The reaction of 4,7-diehlorofuro[2,3-d]pyridazine (1) with potassium cyanide in DMSO gave two products, (E)-3,6-diehloro-5-(2-cyanovinyl)-4-hydroxypyridazine (II) and 5,8-dichloro-2-oxo-2H-pyrano[2,3-d]pyridazine (III) as a result of ring opening or ring expansion. A new ring system, 2-oxo-2H-pyrano[2,3-c]pyridazines (IX, XII, XIII) was obtained from 5,8-dichloro-3-methyl-2-oxo-2H-pyrano[2,3-d]pyridazine (VI).     

Living radical graft polymerization of methyl methacrylate to polyethylene film with typical and reverse atom transfer radical polymerization

Nickel‐mediated atom transfer radical polymerization (ATRP) and iron‐mediated reverse ATRP were applied to the living radical graft polymerization of methyl methacrylate onto solid high‐density polyethylene (HDPE) films modified with 2,2,2‐tribromoethanol and benzophenone, respectively. The number‐average molecular weight (M_n) of the free poly(methyl methacrylate) (PMMA) produced simultaneously during grafting grew with the monomer conversion. The weight‐average molecular weight/number‐average molecular weight ratio (M_w/M_n) was small (<1.4), indicating a controlled polymerization. The grafting ratio showed a linear relation with M_n of the free PMMA for both reaction systems. With the same characteristics assumed for both free and graft PMMA, the grafting was controlled, and the increase in grafting ratio was ascribed to the growing chain length of the graft PMMA. In fact, M_n and M_w/M_n of the grafted PMMA chains cleaved from the polyethylene substrate were only slightly larger than those of the free PMMA chains, and this was confirmed in the system of nickel‐mediated ATRP. An appropriate period of UV preirradiation controlled the amount of initiation groups introduced to the HDPE film modified with benzophenone. The grafting ratio increased linearly with the preirradiation time. The graft polymerizations for both reaction systems proceeded in a controlled fashion. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3350–3359, 2002     

Flavin mononucleotide chemiluminescence in cationic micellar media for determination of chromium(III + VI) by flow injection

The flavin mononucleotide chemiluminescence system, originally developed for the determination of copper(II), is modified with cationic surfactant micelles for the determination of chromium(III + VI). In order for chromium to be detected predominantly, the copper-induced luminescent reaction is significantly suppressed by virtue of the cationic micellar effect. The limit of detection (signal-to-noise ratio = 2) is 5 × 10^?8 M chromium (50-μl sample injection).     

Solid-state electrochemical detector for carbon monoxide at sub-ppm concentrations

Carbon monoxide reacts with iodine pentoxide at 42°C to produce iodine vapor, which is dtected by a solid-state electrochemical detector, essentially a Pt/AgI/Ag galvanic cell. The response begins to rise steeply 3.7 s after a 1.1-ml gas sample is introduce and reaches a maximum after a further 1.2 s. The response is linearly related to the concentration of carbon monoxide up to 2 ppm from the detection limit of 0.03 ppm. Interferences such as H₂S and C₂H₄ are removed by 5A molecuarl sieve; H₂ (1%), CH₄ (5%) and C₂H₄ (5%) are without effect.     

On log canonical divisors that are log quasi-numerically positive

Let (X Δ) be a four-dimensional log variety that is projective over the field of complex numbers. Assume that (X, Δ) is not Kawamata log terminal (klt) but divisorial log terminal (dlt). First we introduce the notion of “log quasi-numerically positive”, by relaxing that of “numerically positive”. Next we prove that, if the log canonical divisorK _X+Δ is log quasi-numerically positive on (X, Δ) then it is semi-ample.     

Synthesis and reaction of 2,7-dimethylpyrrolo[1,2-A]quinoline with electrophilic reagents

2,7-Dimethylpyrrolo[1,2-a]quinoline (1) was synthesized from 2,6-dimethylquinoline and bromoaeetone via a Tsebitsehibabin reaction. The electrophilic substitution reactions of I, namely, nitrosation, acylation, diazonium coupling, formylation, bromination, and nitration were studied.     

Electron spin resonance studies of manganese(II) and copper(II) salts of poly(ethylene-co-methacrylic acid)s

The ionic interaction of poly(ethylene-co-methacrylic acid) ionomer neutralized with Mn²⁺ or Cu²⁺ was studied by ESR spectroscopy to explore the local structure in the ionic aggregate. ESR spectra of the ethylene ionomer were obtained as functions of degree of neutralization and temperature. The existence of both isolated and aggregated cations in the ionomer was confirmed by ESR. In addition, the formation of a Cu²⁺?Cu²⁺ dimer structure similar to the crystal structure of copper acetate monohydrate was found in ethylene ionomer containing the Cu²⁺. Cation-cation interactions changed markedly around 70°C with increasing temperature, representing the onset of the motion of cations in the aggregated ionic structure.     

Cyclic flow-injection determination of copper with hexadecyltrimethylammonium bromide micelle-enhanced,fluorescein-sensitized chemiluminescence detection

In the flow-injection system reported, the reagent stream is continuously cycled. The circulating chemiluminescence reagents (β-nitrostyrene/NaOH/hexadecyltrimethylammonium bromide sensitized with fluorescein) allowed 0.1–10 ng of copper(II) to be determined in hundreds of successive injections, even with samples of sea water or a solution of zinc dust.