Identification of a small-molecule inhibitor of DNA topoisomerase II by proteomic profiling

BNS-22, a chemically synthesized derivative of the natural plant product GUT-70, has antiproliferative activity against human cancer cells, the mechanism of which is unknown. Here, we identify a target of BNS-22 by proteomic profiling analysis, which suggests that BNS-22 belongs to the same cluster as ICRF-193, a DNA topoisomerase II (TOP2) catalytic inhibitor. BNS-22 inhibits kinetoplast DNA decatenation that is mediated by human TOP2α and TOP2β in?vitro at an IC(50) of 2.8 and 0.42?μM, respectively. BNS-22 does not affect DNA damage and antagonizes TOP2 poison-mediated DNA damage. Like ICRF-193, BNS-22 induces mitotic abnormalities, characterized by impairments in chromosome alignment and segregation, thereby causing polyploidy in HeLa cells. These results indicate that BNS-22 targets TOP2 and acts as its catalytic inhibitor.     

Controlled Polarizability of One‐Nanometer‐Thick Oxide Nanosheets for Tailored,High‐κ Nanodielectrics

An important challenge in current microelectronics research is the development of techniques for making smaller, higher‐performance electronic components. In this context, the fabrication and integration of ultrathin high‐κ dielectrics with good insulating properties is an important issue. Here, we report on a rational approach to produce high‐performance nanodielectrics using one‐nanometer‐thick oxide nanosheets as a building block. In titano niobate nanosheets (TiNbO₅, Ti₂NbO₇, Ti₅NbO₁₄), the octahedral distortion inherent to site‐engineering by Nb incorporation results in a giant molecular polarizability, and their multilayer nanofilms exhibit a high dielectric constant (160–320), the largest value seen so far in high‐κ nanofilms with thickness down to 10 nm. Furthermore, these superior high‐κ properties are fairly temperature‐independent with low leakage‐current density (<10^?7 A cm^?2). This work may provide a new recipe for designing nanodielectrics desirable for practical high‐κ devices.     

0.4-V logic-library-friendly SRAM array using rectangular-diffusion cell and delta-boosted-array voltage scheme

We designed a logic-library-friendly SRAM array. The array uses rectangular-diffusion cell (RD cell) and delta-boosted-array-voltage scheme (DBA scheme). In the RD cell, the cell ratio is 1.0, and it reduces the imbalance of the cell ratio. A low supply voltage deteriorates the static noise margin, however, the DBA scheme compensates it. Using the combination of RD cell and DBA scheme, a 32-kB test chip achieves 0.4-V operation at 4.5-MHz frequency, 140-/spl mu/W power dissipation, and 0.9-/spl mu/A standby current.     

Preliminary communication Thermotropic liquid crystals of polyesters having a mesogenic p,p' -bibenzoate unit X. Distinct orientation of molecules in a thin SmCA film stretched from isotropic melt, providing evidence for the biaxiallity of the SmCA p

A thin oriented SmC film of a main-chain polyester was prepared by drawing from the A isotropic melt, and X-ray patterns were observed by irradiation from three characteristic positions relative to the film. The results clarify the biaxiallity of the SmC phase, with a A distinct molecular orientation where the mesogenic groups are tilted in a zigzag manner in a direction perpendicular to the film surface. Such a biaxial orientation is considered to result from the relaxation from the extended arrangement of the mesogenic groups on stretching to the stable zigzag arrangement.     

Synthesis of (+)-vinblastine and its analogues

A synthetic route to vinblastine and its analogues with an ethynyl group, which features a stereoselective coupling of an 11-membered key intermediate with vindoline, is described. Transformations of the alkynyl moiety including a partial reduction as well as a Sonogashira coupling furnished a variety of analogues.     

Influence of cyclohexane vapor on stick-slip friction between mica surfaces

Stick-slip friction between mica surfaces under cyclohexane vapor has been investigated with the Surface Force Apparatus. The dynamic shear stress decreased from 60 to 10 MPa with increasing relative vapor pressure (rvp) from 5% to 50%. Between a rvp of 50% and 80%, the shear stress remained at approximately 10 MPa, with a slight decrease on increasing the rvp. At a rvp greater than 80%, the values of shear stress were below 5 MPa. The stick-slip behavior was observed in the rvp range of 20% to saturation. When the rvp reached 20%, stick-slip appeared but faded out with sliding time. At a rvp greater than 50%, the stick-slip pattern was stable without fading. By taking into account the size of the meniscus formed by capillary condensation of the liquid around the contact area and the Laplace pressure, the dependence of shear stress and the stick-slip modulation on rvp suggests that the origin of the stick-slip observed in cyclohexane vapor is as follows: At a rvp greater than 50%, where stable sick-slip is observed, the stick-slip caused by the cyclohexane layering in the contact area is of essentially the same origin as that observed with mica surfaces sliding in bulk cyclohexane liquid. As with the bulk liquid experiment, decreasing the layer thickness (or the number of the layers) between the surfaces increases the shear stress at the onset of slip. In the vapor phase experiments, the stick-slip is enhanced by the increase of the negative Laplace pressure in the capillary condensed liquid, thereby forcing the surfaces toward each other more strongly with decreasing rvp. In the rvp range between 20% and 50%, where the fading stick-slip is observed, the condensate liquid seeps into the contact area under the influence of the applied tangential force and thus triggers the slip motion. Due to the small condensation volume, the liquid condensed around the contact area is exhausted in the process of repeating stick-slip. As the slip length is limited to the meniscus size, the stick-slip amplitude becomes smaller, and eventually the surfaces start sliding without stick-slip.     

Tuning the thermochromism of water-soluble poly(3-thiopheneacetic acid) conjugated polymer by complexation with zwitterionic polymer

The spectral properties and phase behavior of the complexes of the water-soluble poly(3-thiopheneacetic acid) (P3TAA) conjugated polymer with zwitterionic 3-dimethyl(methacryloyloxyethyl) ammonium propane sulfone (PDMAPS) polymer were explored. A dramatic change in both electronic spectra and upper critical solution temperature (UCST) of P3TAA-PDMAPS complex solution was observed depending on the molar ratio of P3TAA and PDMAPS, suggesting that a conformational transition due to complexation occurred. The UV–vis λ_max of P3TAA-PDMAPS complex solutions was changed dramatically in a narrow temperature range around a UCST and found to be varied over approximately a 40 nm range by the temperature change of about 20 °C.     

Thermoelectric Properties of Ga-Doped Ba8Al x Si46−x Clathrate

Single-crystalline Ba₈Al _x Ga _y Si_46?x?y clathrates were synthesized by the arc melting method and Czochralski method without subsequent treatment, and their thermoelectric properties were compared with those of Ba₈Al _x Ga _y Si_46?x?y and Ba₈Al _x Si_46?x clathrates with almost the same carrier concentration as estimated from the similar Seebeck coefficient and the Zintl concept. The resistivity of Ba_7.8Al_5.3Ga_7.4Si_33.3 was lower than that of Ba_7.9Al_12.6Si_33.4. The specific electrical resistance of Ba_7.9Al_12.6Si_33.4 and Ba_7.8Al_5.3Ga_7.4Si_33.3 was 0.573 mΩ cm and 0.282 mΩ cm at 750 K, respectively. The band structure of Ba₈Al₈Ga₈Si₃₀ and Ba₈Al₁₆Si₃₀ was estimated by first-principle calculations using density functional theory with the local density approximation. Based on these calculations, it was found that the shape of the bottom of the conduction band for Ba₈Al _x Si_46?x clathrate changed slightly on Ga doping and the radius of curvature of the bottom of the conduction band for Ba₈Al₈Ga₈Si₃₀ clathrate was lower than that for Ba₈Al₁₆Si₃₀ clathrate. These results indicate that the mobility was enhanced by Ga doping of Ba₈Al _x Si_46?x clathrate. We also synthesized single-crystalline Ga-doped Ba₈Al _x Si_46?x clathrate. The electrical resistivity decreased dramatically due to the single-crystallization because of reduced electron scattering on grain boundaries. These results suggest that Ga doping and single-crystallization are effective for improvement of the thermoelectric properties of Ba₈Al _x Si_46?x clathrate.     

Thermoelectric Property Dependence and Geometry Optimization of Peltier Current Leads Using Highly Electrically Conductive Thermoelectric Materials

Thermoelectric materials are promising candidates for use in energy-saving devices in many fields. They are also useful in superconducting applications such as those using Peltier current leads (PCLs) to reduce system heat loss. In the case of PCLs, consideration must be given to Joule heating. Furthermore, the performance of PCLs is intricately dependent on their thermoelectric properties. In addition to the figure of merit Z, consideration of the electrical conductivity is also important for the design of high-performance PCLs. In this paper, we discuss the resistivity dependence of the performance of PCLs using model parameters obtained from real devices.