The RING-finger protein haprin: domains and function in the acrosome reaction

The RBCC (RING finger, B-box type zinc finger, coiled-coil domain) motif family contains a large number of proteins implicated in many cellular processes, including vesicle exocytosis. The acrosome reaction, the sperm exocytotic event that is required for fertilization, involves essentially the same process of intracellular membrane fusions as vesicular exocytosis in somatic cells. We have previously isolated a haploid-germ-cell-specific gene designated haprin, which encodes a RBCC motif protein that plays a role in the acrosome reaction of sperm by mediating protein complex formation via the RBCC motif. In this review, we describe the potential role of Haprin in the molecular mechanisms of acrosome reaction, as compared with some other RBCC proteins. The conserved structure and localization of the Haprin protein in human and mouse suggest an indispensable role for Haprin in the functioning of mammalian sperm.     

An efficient stereoselective synthesis of difluoromethylated alkenes in a microreactor

Synthetic utility of microreactors and highly stereoselective isomerization (>99:<1) of terminal difluoromethylated alkenes to (E)-difluoromethylated alkenes with TBAF in DMF, are described.     

Electrical Properties of Silver Photodoped Amorphous Red Phosphorus

Abstract

Effects of photodoping and thermal doping of silver into sputtered amorphous red phosphorus films (a-P_red) on the electrical properties are studied. The d. c. efectrical conductivity of the photodoped a-p_red at room temperature is about 1×10^?5 Scm^?1 which is a very high value comparing with that of the undoped a-p_red (1×10^?14 Scm^?1). The activation energy for the conduction of the photodoped a-P_red is lower than that of the a-p^red. In contrast, the activation energy of the thermally doped a-p_red is essentially the same as that of the undoped a-p_red. SEM-EDX analyses show that colloidal silver was deposited in the thermally doped a-p_red but not in the photodoped a-p_red. It seems that the photo-doping involves the ionization process of silver by illumination, i.e., Ag^o → Ag⁺ + e^?.     

Analysis of detected signal performance in multi-tracks of optical disk memory using convex-shaped recording mark

The possibility of multi-valued optical disk memory by using a convex-shaped recording mark fabricated by two-photon absorption is investigated. We fabricate a numerical model for convex-shaped recording marks and evaluate the signal characteristics in terms of the signal-to-noise ratio (SNR). The numerical results show that 6 bit data can be realized when the acceptable average SNR is 2 and a length of the mark is 4T.     

Single structure widely distributed in a GeTe-Sb2Te3 pseudobinary system: a rock salt structure is retained by intrinsically containing an enormous number of vacancies within its crystal

GeTe(1-x)-Sb2Te3(x) sputtered amorphous film was crystallized into a simple NaCl-type structure through instantaneous laser irradiation over a wide composition range from x = 0 to at least 2/3. When the ratio of Sb2Te3 increases, a vacancy is generated at every Na site for two Sb atoms. The fraction of vacancies, v(x), changes according to x/(1 + 2x), and the cubic root unit cell volume varies with a strong correlation to v(x). Through these created vacancies, valence electrons provided by adjacent Ge/Sb and Te atoms remain constant regardless of the composition, ensuring that these electrons occupy predominantly the bonding molecular orbitals. This results in crystal chemical stability, with the closed shell p-p bondings in the valence electrons arranging the crystal's atomic configuration into an NaCl-type structure.     

Implementation of quantum gate operations in molecules with weak laser fields

We numerically propose a way to perform quantum computations by combining an ensemble of molecular states and weak laser pulses. A logical input state is expressed as a superposition state (a wave packet) of molecular states, which is initially prepared by a designed femtosecond laser pulse. The free propagation of the wave packet for a specified time interval leads to the specified change in the relative phases among the molecular basis states, which corresponds to a computational result. The computational results are retrieved by means of quantum interferometry. Numerical tests are implemented in the vibrational states of the B state of I2 employing controlled-NOT gate, and 2 and 3 qubits Fourier transforms. All the steps involved in the computational scheme, i.e., the initial preparation, gate operation, and detection steps, are achieved with extremely high precision.     

Telluroxide elimination by direct oxidation of alkyl phenyl telluride

Treatment of sec-alkyl phenyl tellurides, except for the cyclohexyl system, with m-chloroperbenzoic acid(MCPBA) in diethyl ether readily afforded the corresponding olefins in good yields presumably via telluroxide elimination together with small amounts of alcohols and ketones. In the pri-alkyl and cyclohexyl cases the adducts between MCPBA and the tellurides were isolated as stable organotellurium(IV) compounds which gave similar elimination products by neat pyrolysis at 220–2500°C.     

Novel approach for catalytic cyclopropanation of alkenes via (2-furyl)carbene complexes from 1-benzoyl-cis-1-buten-3-yne

The reaction of conjugated ene-yne-ketones 3 with a variety of alkenes in the presence of a catalytic amount of Cr(CO)(5)(THF) at room temperature gives (2-furyl)cyclopropanes in good yields. These cyclopropanation reactions proceed via (2-furyl)carbene-chromium intermediates 4 formed in situ from ene-yne-ketones 3. Late transition metals, such as [RuCl(2)(CO)(3)](2), [RhCl(cod)](2), PdCl(2), and PtCl(2), also catalyze effectively the cyclopropanation of styrene with 3.     

Anisotropic phase separation of polymer blends induced by polarization-selective photoisomerization

Anisotropic phase separation of polystyrene/poly(vinyl methyl ether) (PS/PVME) blends was induced by photoisomerization of trans-stilbene moieties labeled on the PS chains (abbreviated hereafter as PSS chains) using linearly polarized light. As temperature increases, the anisotropy becomes weaker and eventually disappears at 10°C above the glass transition of the PSS component. It was concluded that the elastic stress associated with the spatial distribution of the reaction is responsible for this morphological anisotropy.     

Synthesis of regiocontrolled polymer having 2-naphthol unit by CuCl-amine catalyzed oxidative coupling polymerization

Regiocontrolled polymer (2) having 2-naphthol unit was prepared by oxidative coupling polymerization of bis(2-naphthol) (1). Polymerizations were conducted in dichloromethane in the presence of [di-μ-hydroxo-bis(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride [CuCl(OH)TMEDA] under air at room temperature, producing polymers with number-average molecular weights up to 12,000. The structure of polymer 2 was characterized by 270 MHz ¹H–NMR and 68.5 MHz ¹³C–NMR spectroscopies and was estimated to consist almost completely of 1,1′-linkage. The polymer was readily soluble in polar aprotic solvents and tetrahydrofuran at room temperature. Thermogravimetric analysis of polymer 2 showed 10% weight loss at 450°C in nitrogen. The model reactions were studied to clarify the applicability of CuCl(OH)TMEDA for coupling of naphthol derivatives. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3702–3709, 1999