Effective gauge theory and the effect of heavy quarks in Higgs boson decays

A general framework is given for evaluating the contributions of as yet undiscovered heavy quarks to the gluonic decay rate of the Weinberg-Salam type Higgs boson. Since the Yukawa coupling of the Higgs boson to a quark pair is proportional to the quark mass, loop graphs involving heavy quarks have a non-vanishing effect on the gluonic decay width of the Higgs boson. This effect of heavy quarks with massesM _j(j=t,...) much greater than the Higgs boson massm _H is calculated in an effective gauge theory. The effects of two different kinds of large logarithms, lnM _j ² /μ m _h ² /μ ² are separated and summed up by the renormalization group method. It is found that the higher order QCD corrections are large and that the gluonic contribution to the hadronic decay width is significant if there are more than three generations. The Higgs decay width can therefore be used to probe the number of generations of heavy quarks.     

Stereoregularity of radically polymerized poly(alkyl acrylates) and poly(trimethylsilyl acrylates) and the preparation of syndiotactic poly(methyl acrylate)

Nuclear magnetic resonance (NMR) spectroscopy was used to determine the stereoregularity of radically polymerized poly(ethyl acrylates), poly(trimethylsilyl acrylates), and poly(isopropyl acrylate-α,β-d₂). The ethyl acrylate polymers consisted of a random configuration having about 50% of isotactic diads, and their stereoregularities were independent of the polymerization temperature (40 to ?78°C). Poly(trimethylsilyl acrylates) and poly(isopropyl acrylate-α,β-d₂) prepared at low temperatures had a syndiotactic configuration. Syndiotactic poly(methyl acrylate) was derived from syndiotactic poly(trimethylsilyl acrylate). For poly(methyl acrylate), an approximate estimation of the stereoregularity by infrared spectroscopy was proposed.     

Synthesis of myo-inositol derivatives required for the total synthesis of surugatoxin, prosurugatoxin, and neosurugatoxin

Two myo-inositol derivatives (4) and (5), required for the total synthesis of surugatoxin, prosurugatoxin, and neosurugatoxin, were prepared. Synthesis of (+/-)-2,3-O-cyclohexylidene-4,5-O-isopropylidene-1-O-methoxymethyl-myo-i nositol (4) was achieved from (+/-)-1-O-benzoyl-2,3-O-cyclohexylidene-4,5-O-isopropylidene-myo-inosito l (6) in 4 steps, and (-)-2,3-O-cyclohexylidene-1,4-di-O-methoxymethyl-5-O-[2',3',4'-tri-O-ace tyl- beta-D-xylopyranosyl]-myo-inositol (5) was synthesized from (+/-)-1-O-benzoyl-2,3-O-cyclohexylidene-5,6-O-isopropylidene-myo-inosito l (12) in 7 steps.     

Semiconductor-catalyzed photocycloreversion,valence isomerization and [1,3]-sigmatropic rearrangement

The semiconductor-catalyzed photochemical [2+2]cycloreversion of n-methylquinolone dimer, valence isomerization of hexamethyl(Dewar)benzene, and [1,3]-sigmatropic rearrangement of 2,2-bis(4-methoxyphenyl)-1-dideuteriomethylenecyclopropane gave N-methylquinolone, hexamethylbenzene, and 2,2-bis(4- methoxyphenyl)-3,3-dideuterio-1-methylenecyclopropane, respectively.     

The effect of molecular crowding with nucleotide length and cosolute structure on DNA duplex stability

The thermodynamics of DNA duplex structures in the presence of high concentrations of cosolutes in solution were investigated to discern nucleic acid structures and functions in living cells. In the presence of ethylene glycol (EG) and poly(ethylene glycol) (PEG) (MW = 200-8000), the stability of the oligomer DNA duplexes with differing nucleotide length varied, depending on the nucleotide length as well as the size of PEG. It was also revealed that the decrease of water activity is the primary factor for destabilization of the short (8-mer) duplex by addition of high molecular weight PEGs as well as low molecular weight PEGs and other low molecular weight cosolutes. In addition, the number of water molecules taken up per base pair formation was the same for all the PEGs and for 1,2-dimethoxyethane, which was greater than in the cases of glycerol, EG, 1,3-propanediol, and 2-methoxyethanol, suggesting that the solvation of nucleotides may differ, depending on the cosolute structure. These findings are useful not only for understanding nucleic acid structures and functions in cells but also for the design of oligonucleotides applicable for cells, such as antisense nucleic acids, RNAi, and DNA chips.     

SOL-detectability of liver SPECT--analysis of the structure of ROC-curve

The purpose of this study is to evaluate the clinical efficacy of liver SPECT (single photon emission computed tomography). The two examinations were performed in 76 cases with SOL (space occupying lesion) and 58 normal cases. The results of the image reading by the planar image only (PS) and that of the image reading by the combination of PS and SPECT (PS + SPECT) were analyzed by ROC (receiver operating characteristic) analysis. The ROC curves showed that SPECT appears to reduce the number of results which were equivocal by the image reading of PS only. The detectability of SPECT for SOL in the left lobe of liver was less than that of PS without statistical significance. However, the performance of SPECT for SOL in the right lobe of liver was significantly better than that of PS.     

Tetracyanoquinodimethanide adsorbed on a silica gel modified with titanium oxide for electrocatalytic oxidation of hydrazine

The electrocatalytical oxidation of hydrazine at low potential using tetracyanoquinodimethanide adsorbed on silica modified with titanium oxide was investigated by cyclic voltammetry and amperometry. The modified electrode was prepared modifying a carbon paste electrode employing lithium tetracyanoquinodimethanide adsorbed onto silica gel modified with titanium oxide. This electrode showed an excellent catalytic activity and stability for hydrazine oxidation. With this modified electrode, the oxidation potential of hydrazine was shifted toward less positive value, presenting a peak current much higher than those observed on a bare GC electrode. The linear response range, sensitivity and detection limit were, respectively, 2 up to 100 μmol l⁻¹, 0.36 μA l μmol⁻¹, and 0.60 μmol l⁻¹. The repeatability of the modified electrode evaluated in term of relative standard deviation was 4.2% for 10 measurements of 100 μmol l⁻¹ hydrazine solution. The number of electrons involved in hydrazine oxidation (4), the heterogenous electron transfer rate constant (1.08 × 10³ mol⁻¹ l s⁻¹), and diffusion coefficient (5.9 × 10⁻⁶ cm² s⁻¹) were evaluated with a rotating disk electrode.     

Capillary electrophoresis as a nanoreactor of separation capability: on-capillary reaction catalyzed by transition metal ions

The catalytic oxidation of 1,2-dihydroxy-benzene-3,6-disulfonate (tiron) by metal ions has been studied for detection of the metal ions in capillary electrophoresis (CE). Although Co(2+) shows the strongest catalytic capability, some other metal ions also catalyze this reaction. If metal ions encounter a H(2)O(2 )zone after electrophoretic separation in the running buffer containing tiron, tiron is catalytically oxidized while the metal ion passes through the H(2)O(2) zone. Anionic tiron radicals produced by the reaction are finally measured by the detector; in this scheme, the capillary acts as a nano- or microreactor as well as a microseparator. The effective capillary length can be controlled by changing the interval between metal ion and H(2)O(2) injections. This scheme has been successfully applied to the detection of Co(2+), Cu(2+), Mn(2+), and VO(2+). The detectability is discussed from several viewpoints, such as the intrinsic catalyst ability of metal ions, the kinetics of the catalytic reaction, and reaction times determined by the mobility of the zone of the metal ion. Some strange behaviors, which cannot be predicted by batch experiments, are also reported.     

Synthesis and Synthetic Application of Phosphonoketene Dithioacetals. New Synthesis of Dithioallenes and (alpha-Dithiocarboxyvinyl)phosphonates

Phosphonoketene dithioacetals 3a-e were obtained in good yields by the reaction of ethyl phosphonoacetates 1a,b with 2-4 equiv of thiols 2a-c in the presence of an alkylaluminum dichloride or dialkylaluminum chlorides. Reaction of 2,2-dithio-1-phosphonovinyl anions with aldehydes afforded allylic alcohols 4-7, 11-18 in good to moderate yields. Treatment of the alcohols 4-6 with t-BuOK in THF led to symmetrical [2 + 2] cycloadducts 20-22 of 1,1-(ethylenedithio)allenes in moderate yields, while a similar reaction of the alcohols 11-13 produced a mixture of symmetrical and unsymmetrical [2 + 2] cycloadducts of 1,1-(trimethylenedithio)allenes,23a-25a and 23b-25b, in 55-94% yields. The alcohol 15 on a similar treatment gave 3-tert-butyl-1,1-bis(ethylthio)allene (26) in quantitative yield. The structures of 20 and 23b were determined by X-ray analysis. Treatment of the alcohols 15 and 18 with trifluoromethanesulfonic acid/n-Bu(4)NX (X = Br, I) or triphenylphosphine/CBr(4) in CH(2)Cl(2) afforded alpha-phosphonodithioacryclic acid esters 34 and 35 in 25-52% yields. The tandem Michael-Wittig reaction of 35 with sodium salt of 2-pyrrolecarbaldehyde in DMF gave ethyl 3-phenyl-3H-cyclopenta[a]pyrrole-2-dithiocarboxylate (36) in 25% yield.     

FOURIER-TRANSFORM INFRARED SPECTROSCOPIC STUDY OF THE STRUCTURE OF CHLOROPHYLL a and CHLOROPHYLL b IN HIGHLY DILUTE WATER-SATURATED CARBON TETRACHLORIDE SOLUTIONS

Abstract— Fourier-transform (FT) infrared (IR) absorption spectra have been measured for chlorophyll a (Chi a ), chlorophyll b (Chi b ), pheophytin a (Pheo a ), and pheophytin b (Pheo b ) in highly dilute (10^-5-10^-6 M ) water-saturated carbon tetrachloride solutions. Frequencies of IR bands due to C=O stretching modes of the 9-keto group indicate that Chi a assumes largely a dimeric structure in the concentrated (10^-2-10^-3 M ) water-saturated carbon tetrachloride solutions but it remains mostly a monomer with one or two coordinated water molecules in dilute (10^-5-10^-6 M ) solutions. Although it seems that Chi b also assumes predominantly dimeric form in concentrated solutions and monomelic form in dilute solutions, the relative intensity change of two C=O stretching bands ascribed to the free and coordinated 3-aldehyde groups with decreasing concentration suggests that the aldehyde group is also involved in formation of the dimer. The relative intensity of two C=O stretching bands due to the free and coordinated aldehyde groups changes significantly for Pheo b in water-saturated carbon tetrachloride solutions. This observation suggests that some of Pheo b also assume dimeric form via the aldehyde group in concentrated solutions.