New methods and reagents in organic synthesis. 56. Total syntheses of patellamides B and C,cytotoxic cyclic peptides from a tunicate 2. Their real structures have been determined by their syntheses.

The proposed structures of patellamides B and C, cytotoxic lipophilic cyclic peptides from a marine tunicate, have been revised on the basis of the spectral data of their partial hydrolysates, and their revised structures have been synthetically confirmed by the use of diphenyl phosphorazidate(DPPA) and diethyl phosphorocyanidate(DEPC).     

Stochastic differential equations for multi-dimensional domain with reflecting boundary

Summary In this paper we prove that there exists a unique solution of the Skorohod equation for a domain inR ^d with a reflecting boundary condition. We remove the admissibility condition of the domain which is assumed in the work [4] of Lions and Sznitman. We first consider a deterministic case and then discuss a stochastic case.     

InGaAsP multiple quantum well edge-emitting light-emitting diode showing low coherence characteristics using selective-area metalorganic vapor phase epitaxy

Low coherence multiple-quantum well edge-emitting light-emitting diodes were obtained using selective-area metalorganic vapor-phase epitaxial growth, which utilized growth rate enhancement on an open stripe region between mask stripes. An optical absorption region, which was controlled by selective-area growth, was introduced to suppress optical feedback. At a driving current of 100 mA and an ambient temperature of 25°C, a power of 55 μW was coupled into a single-mode fiber, and a broad spectrum without spectral ripple was observed. Low coherence characteristics and very small temperature dependence were obtained in the temperature range from -40°C to 85°C. The modulation bandwidth was 210 MHz at a bias current of 100 mA.     

Optimization of mark edge recording waveform for a phase change rewritable optical disk using a 680 nm laser diode

A high density mark edge recording method on a phase change rewritable disk is reported. A carrier-to-noise ratio of 55 dB for a mark length of 0.55,μm is obtained by using a 680 nm, NA 0.6 head and a phase change rewritable disk. In mark edge recording, it is necessary to record each mark in correct length. A new laser power modulation pattern is proposed. This pattern consists of a first-pulse, a multi-pulse chain and a last-pulse. Both positions of the first-ptilse and the last-pulse are movable. By adjusting these positions, a jitter, σ/T_w (T_w is window margin), is improved to 6.5% in high density EFM (Eight to Fourteen Modulation) recording of 0.4 μm/bit.     

The electronic structure of naphthalene

Electronic energy levels of naphthalene were calculated by semi-empirical ASMO-CI method including a part of doubly excited configurations as well as all singly excited configurations. The result obtained seems to indicate that with respect to the amount of the mixing of CI to be invoked it is sufficient to take into account all singly excited configurations only.The interpretation of spectra was also discussed.

---

Zusammenfassung Die Energieniveaus der Elektronen im Naphthalin-Molekül wurden mittels einer halbempirischen ASMO-CI-Methode unter Einschluß einer Reihe von einfach und doppelt angeregten Zuständen berechnet. Dabei zeigt sich, daß es wahrscheinlich genügt, nur einfach angeregte Zustände in die Rechnung einzubeziehen.

---

Résumé Les états énergétiques du naphthaléne ont été calculés par une méthode ASMO-CI semiempirique où une partie des configurations diexcitées et toutes les configurations monoexcitées ont été inclues. Le résultat indique qu'il suffit de ne tenir compte que des configurations monoexcitées. Les spectres sont discutés.

---

---

One of us (H. I.) wishes to express his thanks to Professor K. Suzuki for encouragement throughout this work.     

Synthesis and mechanochemical properties of biobased ABCBA-type pentablock copolymers comprising poly-d-lactide (A), poly-l-lactide (B) and poly(1,2-propylene succinate) (C)

The ABCBA pentablock copolymers (p-d -l -PPS) comprising poly(d -lactide) (PDLA: A), poly(l -lactide) (PLLA: B) and poly(propylene succinate) (PPS: C) were successfully synthesized by two-step ring-opening polymerization (ROP) of d - and l -lactide using a dihydroxy-terminated PPS as a macro-initiator. The pentablock copolymers revealed the high stereocomplex (sc) crystallinity, thermal stability and elastomeric property in their solution-cast films. It was found that the T_g was found to be proportional to the PPS content, whereas the T_m was proportional to their average block length. The thermal resistivity of the copolymer films was found to be as high as 202°C owing to their sc formation. The copolymers also showed improved stereocomplexibility compared to the enantiomeric mixtures of triblock copolymers (PLLA-PPS-PLLA and PDLA-PPS-PDLA) having similar PLLA and PDLA chain lengths. These pentablock copolymers can afford thermoplastic elastomers or flexible plastic materials having a 100% bio-based content, showing high heat-resistive property.     

Colorimetric detection of spermine and spermidine by zincon in aqueous solution

The anionic organic dye, zincon, was found to be a colorimetric probe for spermine and spermidine at pH 4.0 in pure aqueous solution through its aggregation by electrostatic interactions with them. The addition of spermine and spermidine led to bathochromic shifts with color changes from yellow to purple and dark brown, respectively, while other amines and basic amino acids induced no or minimal spectral and color changes. From Job’s plot and titration experiments, zincon interacted with spermine (+4 charges) and spermidine (+3 charges) in 4:1 and 3:1 stoichiometric ratios, respectively, indicating that each positive charge was bound to one zincon molecule. The detection limits were determined to be 25.1 for spermine and 30.7 nM for spermidine, which were sufficient below the critical concentration for cancer diagnosis. The results indicated that zincon can be a good candidate for simple, convenient colorimetric detection of spermine and spermidine in aqueous solution.     

Molecular imprinting of bisphenol A and alkylphenols using amylose as a host matrix

A novel molecularly imprinted polymer has been created by a radical polymerisation of acryloylamylose in the presence of a template.     

Structure and crystallization of sub-elementary fibrils of bacterial cellulose isolated by using a fluorescent brightening agent

The structure and crystallization of carefully isolated sub-elementary fibrils (SEFs) of bacterial cellulose have been investigated using TEM, WAXD, and high-resolution solid-state ¹³C NMR. The addition of a suitable amount of fluorescent brightener (FB) to the incubation medium of Acetobacter xylinum effectively suppressed the aggregation of the SEFs into the microfibrils, as previously reported. However, this study confirmed for the first time that serious structural change in the SEFs occurs during the removal of excess FB by washing with buffer solutions having pH values higher than 6 or with the alkaline aqueous solution that was frequently used in previous studies. In contrast, the isolation of unmodified SEFs was successfully performed by utilizing a washing protocol employing pH 7 citrate–phosphate buffer solution containing 1% sodium dodecyl sulfate. High-resolution solid-state ¹³C NMR and WAXD measurements revealed that the SEFs thus isolated are in the noncrystalline state in which the pyranose rings of the almost parallel cellulose chains appear to be stacked on each other. The respective CH₂OH groups of the SEFs adopt the gt conformation instead of the tg conformation found in cellulose I _α and I _β crystals, and undergo significantly enhanced molecular motion in the absence of intermolecular hydrogen bonding associated with these groups. The main chains are also subject to rapid motional fluctuations while maintaining the parallel orientation of the respective chains, indicating that the SEFs have a liquid crystal-like structure with high molecular mobility. Moreover, the SEFs crystallize into cellulose I _β when the FB molecules that may adhere to the surface of the SEFs are removed by extraction with boiling 70 v/v% ethanol and 0.1N NaOH aqueous solution. On the basis of these results, the crystallization of the SEFs into the I _α and I _β forms is discussed, including the possible formation of the crystalline-noncrystalline periodic structure in native cellulose.     

Colorimetric detection of Cu2+ using of a mixture of ponceau 6R and a cationic polyelectrolyte in aqueous solution

Journal of Inclusion Phenomena and Macrocyclic Chemistry - A colorimetric chemosensor is reported for Cu2+ by a simple mixture of two commercially available reagents, ponceau 6R (P6R) and...