Supramolecular nanocarrier of siRNA from PEG-based block catiomer carrying diamine side chain with distinctive pKa directed to enhance intracellular gene silencing

An siRNA nanocarrier formed through self-assembly of PEG-based block catiomer possessing two distinct amino groups with different pKa values in a side chain was developed. This design provided the carrier with a sufficient siRNA complexation and an assumed buffering capacity in the endosomes, allowing it to exhibit remarkable gene knockdown abilities as well as sufficient serum tolerability.     

Asymmetric benzoin condensation catalyzed by chiral rotaxanes tethering a thiazolium salt moiety via the cooperation of the component: can rotaxane be an effective reaction field?

Although some reactions on rotaxanes have been reported, the characteristic features of the rotaxanes providing unique reaction fields have hardly been studied, especially as catalyst. In our continuous studies on interlocked molecules such as rotaxanes and catenanes, we have noticed the importance of such interlocked structures with high freedom in functionalized materials such as molecular catalyst. For catalytic asymmetric benzoin condensations, two optically active rotaxanes possessing thiazolium salt moieties were prepared using the binaphthyl group as the chiral auxiliary. The benzoin condensations of aromatic aldehydes catalyzed by the chiral rotaxanes as catalysts gave optically active benzoins with ca. 30% ee in moderate to high chemical yields depending upon the structure of rotaxane and the reaction conditions employed. From the results, two intrarotaxane chirality transfers are confirmed: (i) through-space chirality transfer from wheel to axle and (ii) through-bond chirality transfer controlled with an achiral wheel. Because these asymmetric reaction fields are specific to the rotaxane structure, the importance and possibility of the "rotaxane field" as a particular reaction field is demonstrated in this work.     

Redox behavior of ferrocene-containing rotaxane: transposition of the rotaxane wheel by redox reaction of a ferrocene moiety tethered at the end of the axle

A rotaxane with a ferrocene moiety at the axle terminus was prepared. The redox potential of the ferrocene moiety decreased by ca. 80 mV when the rotaxane had a crown ether wheel capable of moving on the axle. Thus, the stabilization of the oxidized state of the ferrocene moiety is assumed to accompany the transposition of the wheel component on the axle toward the ferrocene moiety. [reaction--see text]     

Gauge coupling unification in grand unified theories with anomalous U1 symmetry

We show that in the framework of grand unified theory (GUT) with anomalous U(1)(A) gauge symmetry, the success of the gauge coupling unification in the minimal SU(5) GUT is naturally explained, even if the mass spectrum of superheavy fields does not respect SU(5) symmetry. Because the unification scale for most realizations of the theory becomes smaller than the usual GUT scale, it suggests that the present level of experiments is close to that sufficient to observe proton decay via dimension 6 operators, p-->e+pi.     

Massadine,a novel geranylgeranyltransferase type I inhibitor from the marine sponge Stylissa aff. massa

Massadine, a highly oxygenated alkaloid, was isolated from the marine sponge Stylissa aff. massa as an inhibitor of geranylgeranyltransferase type I (GGTase I). The structure of massadine has been deduced from spectral data. Massidine inhibited GGTase I from Candida albicans with an IC(50) value of 3.9 microM. [structure: see text]     

Oxidative degradation of poly(isophthaloylhydrazine‐1,2‐diyl)s

The condensation polymerization of isophthalodihydrazide and diphenyl isophthalate affords poly(isophthaloylhydrazine‐1,2‐diyl). High‐molecular‐weight poly(5‐tert‐butylisophthaloylhydrazine‐1,2‐diyl) is prepared by the polycondensation of 5‐tert‐butylisophthalodihydrazide and bis(4‐nitrophenyl) 5‐tert‐butylisophthalate in NMP at 100 °C. T_d of the poly(diacylhydrazine) is observed above 300 °C. No T_g is observed below T_d. The high‐molecular‐weight poly(diacylhydrazine) exhibits a film‐forming ability. The poly(diacylhydrazine) decomposes on treatment with an oxidant such as sodium hypochlorite solution to obtain the corresponding carboxylic acid and nitrogen. However, poly(diacylhydrazine) was stable to oxygen and hydrogen peroxide even in the presence of transition metal ions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6255–6262, 2008     

Molecular distortion effect on ff-emission in a Pr(III) complex with 4,7-diphenyl-1,10-phenanthroline.

The electronic and structural behaviour of a Pr(III) complex with 4,7-diphenyl-1,10-phenanthroline, [Pr(bathophen)(2)(NO(3))(3)], is investigated with respect to the effect of configuration changes on the Pr(III) centre. [Pr(bathophen)(2)(NO(3))(3)] luminesces from the excited states of the ligand and the metal ion. The fluorescence, ff-emission ((1)D(2)-->(3)H(4)), and phosphorescence bands appear at 394, 608.2 and 482 nm, respectively, in the solid state. In acetonitrile, the complex also shows multiple emissions. From the time-resolved emission and the lifetime measurements, the excitation energy-transfer in [Pr(bathophen)(2)(NO(3))(3)] is clarified, that is, the upper excited triplet level of the ligand acts as an energy donor, while the (1)D(2) levels of Pr(III) is the acceptor. Additionally, the emission phenomena of the complex can be modified by molecular distortion, particularly by rotation of the phenyl groups in the ligand.     

Noise analysis of an electro-optic sensor system

Optical Review - This paper describes the noise analysis of an electro-optic (EO) sensor system based on experimental and simulation results. We developed a polarization simulator of the EO sensor...     

First observation of the point spread function of optical transition radiation

We represent the first experimental observation of the point spread function (PSF) of optical transition radiation (OTR) performed at KEK-Accelerator Test Facility extraction line. We have demonstrated that the PSF vertical polarization component has a central minimum with a two lobe distribution. However, the distribution width varied significantly with wavelength. We assume that we observed a severe effect from spherical or chromatic aberrations which are not taken into account in any existing theoretical model. We believe that the result of this work will encourage theoreticians to continue developing the theory as it is important for various transition radiation applications. Nonuniform distribution of the OTR PSF creates an opportunity for developing a submicrometer transverse beam size monitor.