An Analysis of <Emphasis Type="Italic">M/M/s</Emphasis> Queueing Systems Based on the Maximum Entropy Principle

There have been some interesting attempts to derive the equilibrium probability distribution of possible states of queueing systems by using the maximum entropy principle. In particular, Shore introduced an entropy model for the M/M/∞ queueing system. In this paper an inconsistency in Shore's procedure is indicated and an exact entropy model for the multiple server queueing system is presented.     

New approach to the GC separation of hydrocarbons by using LC-like microcolumns

Summary Micropacked columns for liquid chromatography were evaluated for the gas chromatographic separation of hydrocarbons. A glass-lined stainless-steel tube of 30 cm×0.3 mm i.d., packed with 5-m alkyl-modified silica, was employed as the separation column. The micropacked columns were successfully applied to the separation of components of a light oil and a kerosine.     

Microbial deracemization of alpha-substituted carboxylic acids: substrate specificity and mechanistic investigation

A new enzymatic method for the preparation of optically active alpha-substituted carboxylic acids is reported. This technique is called deracemization reaction, which provides us with a route to obtain the enantiomerically pure compounds, theoretically in 100% yield starting from the racemic mixture. This means that the synthesis of a racemate is almost equal to the synthesis of the optically active compound, and this concept is entirely different from the commonly accepted one in the asymmetric synthesis. Using the growing cell system of Nocardia diaphanozonaria JCM3208, racemates of 2-aryl- and 2-aryloxypropanoic acid are deracemized smoothly and (R)-form-enriched products are recovered in high chemical yield (>50%). In addition, using optically active starting compounds and deuterated derivatives as well as inhibitors, we have disclosed the fact that a new type of enzyme takes part in this biotransformation, and that the reaction proceeds probably via the same mechanism as that in rat liver.     

First total synthesis of (±)-oxerine

Total synthesis of (±)-oxerine (1), a monoterpene alkaloid, starting from 3-bromopyridine (7) is described. The key reaction in this sequence is the samarium iodide (SmI₂)-mediated intramolecular cyclization of γ-ethynyl bromide (4).     

2-Acyloxypyrazines. Convenient acylating agents for amines

2-Acyloxypyrazines were found to be useful acylating reagents for amines. The preference of the acylation was for primary amines rather than secondary ones and also for aliphatic amines rather than aromatic ones.     

Magnetic properties of anhydrous and hydrous modifications of potassium-chloranil salt

The temperature dependence of magnetic susceptibility was studied on the anhydrous and hydrous modifications of the potassium-chloranil salt. While the anhydrous salt exhibits a phase transition at 210–270 K from the low spin state to the high spin state, the hydrous modification shows no such phase transition, and remains in a low spin state over the whole temperature range, 70–300 K.     

Structure-activity relationships of rat neuromedin U for smooth muscle contraction.

Rat neuromedin U (r-NMU) and its fragment peptide amides were synthesized by solid-phase methodology. Using a chicken crop smooth muscle contraction assay, the potency of r-NMU and its fragments relative to porcine neuromedin U-8 (p-NMU-8) was r-NMU: 10.25 +/- 2.88, r-NMU (6-23): 8.01 +/- 1.04, r-NMU (10-23): 2.76 +/- 0.46, r-NMU (13-23): 2.81 +/- 0.52, and r-NMU (16-23): 0.88 +/- 0.19, respectively. Two heptapeptides, r-NMU (17-23) and r-NMU (16-22), had a relative potency of 0.61 and 0.03 respectively, and elicited maximal contraction at a dose of 10 microM to a similar degree to p-NMU-8. The other shorter C-terminal fragments did not elicit the maximal contraction or any activity. In a rat uterus contraction assay, r-NMU (13-23), but not r-NMU (16-23), at a dose of 4 nM retained as high a stimulatory activity as r-NMU itself. r-NMU (17-22) was the smallest peptide fragment to elicit the maximal sustained contraction at 10 microM. These results indicate that the amino acid sequence Phe-Leu-Phe-Arg-Pro-Arg, corresponding to positions 17 to 22 of r-NMU, may be essential for contractile activity. N-terminal peptide segments Tyr-Gln-Gly-Pro corresponding to positions 6 to 9, and Ser-Gly-Gly corresponding to positions 13 to 15, appear to be of special importance for potent activity.     

Construction of an electrochemical DNA chip for simultaneous genotyping of single nucleotide polymorphisms

An electrochemical DNA chip was constructed for simultaneous genotyping of single nucleotide polymorphisms (SNPs) using genomic DNA extracted from blood samples. This chip consisted of electrodes located on a single piece of substrate and allele-specific oligonucleotide probes on the electrodes. As a first application, the 4 SNPs (MxA[-88], MxA[-123], MBL[X/Y], and MBL[A/B]), which have association with the efficacy of interferon therapy for HCV patient, were genotyped on the new DNA chip. Following hybridization of PCR products containing the 4 types of fragments, washing, bisbenzimide H33258 (Hoechst 33258) reaction and electrochemical analyses, 59 blood samples were genotyped by the chip method simultaneously. All procedures were completed within 2 h and the results were 100% concordant with those by the direct sequence method. The electrochemical DNA chip is expected to be a practical tool for SNPs genotyping.