Two novel long-chain alkanoic acid esters of lupeol from alecrim-propolis

Two new long-chain alkanoic acid esters of lupeol were isolated together with known triterpenoids, alpha-amyrin, beta-amyrin, cycloartenol, lanosta-7,24-diene-3beta-ol and lupeol from Alecrim-propolis collected in Brazil. The structures were characterized by spectroscopic means.     

Studies on bubble dynamics

In order to clarify the behavior of bubbles which is closely related to cavitation phenomena, the research of the dynamics of bubbles has been intensively conducted and established the research field of bubble dynamics. In this review paper it is intended to describe briefly studies on bubble dynamics including the history in conjunction with the shock wave dynamics. Received 17 June 1996 / Accepted 15 August 1996     

New prenylated C₆-C₃ compounds from the twigs of Illicium anisatum

Two new prenylated C?-C? compounds, cycloillicinone (1) and 4-allyl-2-methoxy-6-(2-methylbut-3-en-2-yl)phenol (2), were isolated from the twigs of Illicium anisatum, and their structures were determined by 2D-NMR methods. Cycloillicinone (1) is a unique prenylated C?-C? that is appended with an additional geranyl unit. Compound 2 was found to show moderate neurite-outgrowth promoting activity in primary cultured rat cortical neurons at a concentration of 10 μM.     

BINOL Aza Macrocycle Derivatives: Synthesis of Dinaphthosulfone Aza Macrocycles Using p-Toluenesulfonic Acid (p-TsOH) in Methanol as an Efficient Route and Evaluation of Their 1H NMR Spectra

Dinaphthosulfone aza macrocycles were synthesized from the reaction of diamines and dinaphthosulfone diester (1,1′-sulfoxobis-(2-naphthoxy(2-methyl acetate))) in methanol in the presence of catalytic amounts of para toluenesulfonic acid (p-TsOH). Dinaphthosulfone diester (1,1′-sulfoxobis-(2-naphthoxy(2-methyl acetate))) was synthesized from the corresponding dinaphthosulfide diester and hydrogen peroxide in formic acid at room temperature. Dinaphthosulfide diester was prepared from initial dinaphtholsulfide diol (1,1′-thio bis(2-hydroxy naphthalene)) and methylchloroacetate. ¹H NMR spectroscopy showed the unusual splittings for these dinaphthosulfone aza macrocycles, and this finding could be proposed as the role of tetrahedral structure of sulfone functional group, hydrogen bonding in the cavity and size of macrocycle.     

Synthesis and preparation of nanoparticles composed of amphiphilic poly(γ-glutamic acid) with different hydrophobic side chains and their potential of membrane disruptive activity

In the development of nanoparticle-based vaccine adjuvants, the interaction between nanoparticles (NPs) and the cells is a key factor. To control them, we focused on the relationship between the hydrophobicity of the side chains and the cell membrane. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA), using various types of hydrophobic side chains, was synthesized and used to prepare NPs for evaluating the membrane disruptive activity. When leucine ethyl ester (Leu), methionine ethyl ester (Met), or tryptophan ethyl ester (Trp) was grafted, each polymer formed monodispersed NPs at physiological conditions. Significantly, NPs composed of Leu and Trp showed a membrane disruptive activity at the endosomal environment (pH 5–6.5), while NPs composed of Met did not show. This might be due to the weak hydrophobicity of Met compared to that of Leu and Trp, which demonstrated that the interaction between NPs and cells could be controlled by designing the polymer compositions.     

Effective separation and C-24 stereochemical assignment of epimeric 24-isopropenylcholesterols

Separation of epimeric 24-isopropenylcholesterols ($\text{1a}$) was effectively achieved by reversed-phase HPLC. The C-24 stereochemistry of these epimers was determined on the basis of chemical and spectroscopic evidence.     

Z2 oscillation of mean charge states of fast Si and Cl ions after passage through thin foils

Z₂ (target atomic number) oscillation of equilibrium charge states has been observed for 30–110 MeV Si and 70 and 110 MeV Cl ions after the passage through 22 different Z₂ foils. This oscillation may be related to the Z₂ oscillation of electron capture cross sections into the projectile K vacancy.     

An improved method for de novo sequencing of arginine-containing, Nalpha-tris(2,4,6-trimethoxyphenyl)phosphonium-acetylated peptides

An improved method for de novo sequencing of arginine-containing peptides modified with succinimidyloxycarbonylmethyl tris(2,4,6-trimethoxyphenyl)phosphonium bromide (TMPP-Ac-OSu) is reported. A tagging reagent, TMPP-Ac-OSu, was introduced to improve the sequence analysis of peptides owing to the simplified fragmentation pattern. However, peptides containing arginine residues did not fragment efficiently even after TMPP-Ac modification at their N-termini. This report describes how fragmentation efficiency of TMPP-Ac-modified arginine-containing peptides was significantly improved by modifying the guanidino group on the side chain of arginine with acetylacetone.     

Characterization of the Fe site in iron-sulfur cluster-free hydrogenase (Hmd) and of a model compound via nuclear resonance vibrational spectroscopy (NRVS)

We have used (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to study the iron site in the iron-sulfur cluster-free hydrogenase Hmd from the methanogenic archaeon Methanothermobacter marburgensis. The spectra have been interpreted by comparison with a cis-(CO)2-ligated Fe model compound, Fe(S2C2H4)(CO)2(PMe3)2, as well as by normal mode simulations of plausible active site structures. For this model complex, normal mode analyses both from an optimized Urey-Bradley force field and from complementary density functional theory (DFT) calculations produced consistent results. For Hmd, previous IR spectroscopic studies found strong CO stretching modes at 1944 and 2011 cm(-1), interpreted as evidence for cis-Fe(CO)2 ligation. The NRVS data provide further insight into the dynamics of the Fe site, revealing Fe-CO stretch and Fe-CO bend modes at 494, 562, 590, and 648 cm(-1), consistent with the proposed cis-Fe(CO)2 ligation. The NRVS also reveals a band assigned to Fe-S stretching motion at approximately 311 cm(-1) and another reproducible feature at approximately 380 cm(-1). The (57)Fe partial vibrational densities of states (PVDOS) for Hmd can be reasonably well simulated by a normal mode analysis based on a Urey-Bradley force field for a five-coordinate cis-(CO)2-ligated Fe site with additional cysteine, water, and pyridone cofactor ligands. A "truncated" model without a water ligand can also be used to match the NRVS data. A final interpretation of the Hmd NRVS data, including DFT analysis, awaits a three-dimensional structure for the active site.     

A Two-on-One Linear Pursuit–Evasion Game with Bounded Controls

A linearized engagement with two pursuers versus a single evader is considered, in which the adversaries’ controls are bounded and have first-order dynamics and the pursuers’ intercept times are equal. Wishing to formulate the engagement as a zero-sum differential game, a suitable cost function is proposed and validated, and the resulting optimization problem and its solution are presented. Construction and analysis of the game space is shown, and the players’ closed-form optimal controls are derived for the case of two “strong” pursuers. The results are compared to those of a 1-on-1 engagement with a “strong” pursuer, and it is shown that the addition of a second pursuer enlarges the capture zone and introduces a new singular zone to the game space, in which the pursuers can guarantee equal misses, regardless of the evader’s actions. Additionally, it is concluded that in the regular zones the closed-form optimal pursuit strategies are unchanged compared to two 1-on-1 engagements, whereas the optimal evasion strategy is more complex. Several simulations are performed, illustrating the adversaries’ behavior in different regions of the game space.