Structure and reactions of pentaquark baryons

We review the current status of the exotic pentaquark baryons. After a brief look at experiments of both positive and negative results, we discuss theoretical methods to study the structure and reactions for the pentaquarks. First we introduce the quark model and the chiral soliton model, where we discuss the relation of mass spectrum and parity with some emphasis on the role of chiral symmetry. It is always useful to picture the structure of the pentaquarks in terms of quarks. As for other methods, we discuss a model-independent method, and briefly mention the results from the lattice and QCD sum rule. Decay properties are then studied in some detail, which is one of the important properties of ⊝⁺. We investigate the relation between the decay width and the quark structure having certain spin-parity quantum numbers. Through these analyses, we consider as plausible quantum numbers of ⊝⁺,J ^P = 3/2⁻. In the last part of this note, we discuss production reactions of ⊝⁺ which provide links between the theoretical models and experimental information. We discuss photoproductions and hadron-induced reactions which are useful to explore the nature of ⊝⁺     

Triviality of Hierarchical Models with Small Negative φ4 Coupling in Four Dimensions

The Kadanoff-Wilson renormalization group (RG) for a class of hierarchical spin models including small negative φ⁴ terms in four dimensions are studied by using Gawędzki and Kupiainen's analysis. We prove triviality for the class, namely prove existence of critical trajectory that leads to the Gaussian fixed point.     

Ferromagnetism Induced by Substitution of the Iron(IV) Ion by an Unusual High‐Valence Nickel(IV) Ion in Antiferromagnetic SrFeO3

Novel cubic perovskites SrFe_1?xNi_xO₃ (0≤x≤0.5) with unusual high‐valence iron(IV) and nickel(IV) ions were obtained by high‐pressure and high‐temperature synthesis. Substantial magnetic moments of Ni^IV, which is intrinsically nonmagnetic with a nominal d⁶ electron configuration, were induced by the large magnetic moments of Fe^IV through orbital hybridization with oxygen. As a result, ferromagnetism with the transition temperature (T_c) above room temperature could be induced.     

Synthesis of antisense oligodeoxyribonucleotide analogues by use of deoxyribonucleoside 3′-bis(1, 1, 1, 3,3,3-hexafluoro-2-propyl) phosphites as new key intermediates

The deoxyribonucleoside 3′-bis(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite units ( 3 ) are used in the chemical synthesis of oligodeoxyribonucleotides on solid supports. The new phosphite units ( 3 ) were prepared easily by reaction of nucleosides and tris-(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite ( 2 ). They are readily activated by N-methylimidazole under very mild conditions on a solid support. This operation involves a one step reaction, which is an advantage over both the phosphite and H-phosphonate approaches. The use of deoxyribonucleoside phosphite intermediates in the synthesis of antisense oligodeoxyribonucleotides is also described.     

Controlled Markov set-chains under average criteria

In this paper, applying an interval arithmetic analysis, we consider the average case of controlled Markov set-chains, whose process allows for fluctuating transition matrices at each step in time. We introduce a v-step contractive property for the average case, under which a Pareto optimal periodic policy is characterized as a maximal solution of optimality equation. Also, in the class of stationary policies, the behavior of the expected reward over T-horizon as T approaches ∞ is investigated and the left- and right-hand side optimality equations are given, by which a Pareto optimal stationary policy is found. As a numerical example, the Taxicab problem is considered.     

A direction controlled Dieckmann type cyclization of half-thiol diesters

A direction controlled Dieckmann type cyclization was performed on treatment of the half-thiol diesters($\text{1}$) with base to give exclusively the β-keto esters ($\text{2}$.     

Development of a novel solid-phase extraction element for thermal desorption gas chromatography analysis

A novel solid-phase extraction element is developed for sorptive enrichment of dilute analytes from liquid samples with high extraction efficiencies due to its larger amounts of polydimethylsiloxane (PDMS) absorbent than the conventional syringe type of solid-phase microextraction (SPME). The extraction element is made of titanium (Ti) open tubular tube (30 mm x 1.2 mm i.d. x 1.6 mm o.d.) coated with a chemically bonded layer of PDMS (500 microm in thickness). The extraction element combined with thermal desorption-gas chromatography-mass spectrometry using a pyrolysis-gas chromatography-mass spectrometry system was used to extract and analyze a typical herbicide, bethrodine in water samples over a concentration range from 2.5 to 2.5 x 10(4) ng/l. Thus obtained calibration curve showed good linearity for the tested whole concentration range with regression coefficient of 0.992. Detection limit of 0.5 ng/l level was achieved and the reproducibility of the measurements for bethrodine at 10 ng/l level was found to be fairly good with relative standard deviation below 7.5%.     

Synthesis and evaluation of 1-arylsulfonyl-3-piperazinone derivatives as factor Xa inhibitors III. Effect of ring opening of piperazinone moiety on inhibition

Compounds containing an ethylenediamine structure in place of the piperazine ring of M55113 (1) and M55551 (2) were synthesized to investigate the effects of a piperazine moiety and evaluated for activity as factor Xa (FXa) inhibitors. Most such compounds, however, exhibited lower activity (1/10-1/100) than that of M55113 and M55551 as FXa inhibitors.     

An influence of a basic side chain moiety on the tautomer ratio between the enamine and methylene imine forms in azole condensed quinoxalines

The reaction of 7-chloro-4-(2-cyano-2-hydroxyvinyl)tetrazolo[1,5-α]quinoxaline 2a with 4-aminopyridine, p-toluidine or p-aminophenol gave 7-chloro-4-(4-pyridylcarbamoylmethylene)-4,5-dihydrotetrazolo[1,5-α]-quinoxaline 7a , 7-chloro-4-(p-tolylcarbamoylmethylene)4, 5-dihydrotetrazolo[1,5-α]quinoxaline 8a or 7-chloro-4-(p-hydroxyphenylcarbamoylmethylene)-4,5-dihydrotetrazolo[1,5-α]quinoxaline 9a , respectively. The reaction of 7-chloro-4-(2-cyano-2-hydroxyvinyl)-1,2,4-triazolo[4,3-α]quinoxaline 2b with 4-aminopyridine, p-toluidine or p-aminophenol afforded 7-chloro4-(4-pyridylcarbamoylmethylene)-4,5-dihydro-1,2,4-triazolo-[4,3-α]quinoxaline 7b , 7-chloro-4-(p-tolylcarbamoylmethylene)-4,5-dihydro-1,2,4-triazolo[4,3-α]quinoxaline 8b or 7-chloro-4-(p-hydroxyphenylcarbamoylmethylene)-4,5-dihydro-1,2,4-triazolo[4,3-α]quinoxaline 9b , respectively. The reaction of compound 2a with 2-aminopyridine or 3-aminopyridine provided 7-chloro-4-(2-pyridyl-carbamoylmethylene)-4,5-dihydrotetrazolo[1,5-α]quinoxaline 10 or 7-chloro-4-(3-pyridyl-carbamoylmethylene)-4,5-dihydrotetrazolo[1,5-α]quinoxaline 11 , respectively. Compounds 7a,b (4-pyridylcarbamoyl) predominated as the enamine tautomer A in a trifluoroacetic acid solution, while compounds 8a,b (p-tolylcarbamoyl) and compounds 9a,b (p-hydroxyphenylcarbamoyl) coexisted as the enamine A and methylene imine B tautomers in a trifluoroacetic acid solution. Moreover, the ratio of the enamine tautomer A elevated in an order of compound 11 (3-pyridylcarbamoyl), compound 10 (2-pyridylcarbamoyl) and compound 7a (4-pyridylcarbamoyl), reflecting an order of the increase in the pKa values of the aminopyridine side chain moieties. In general, the ratio of the enamine tautomer A was higher in the basic carbamoyl derivatives 7–11 than in the neutral ester derivatives 3a,b . From these results, the basic side chain moiety of the tetrazolo[1,5-α]quinoxalines 7a-11 or 1,2,4-triazolo[4,3-α]quinoxalines 7b-9b was found to increase the ratio of the enamine tautomer A in trifluoroacetic acid media.     

Thallium(III) salt-induced olefinic cyclization of o-prenylphenols

Olefinic cyclization of $\text{o}$-prenylphenols ($\text{1}$), ($\text{4}$) and ($\text{6}$) induced by thallium(III) trifluoroacetate was performed.