Removal of histone tails from nucleosome dissects the physical mechanisms of salt-induced aggregation,linker histone H1-induced compaction,and 30-nm fiber formation of the nucleosome array

In order to reveal the roles of histone tails in the formation of higher-order chromatin structures, we employed atomic force microscopy (AFM), and an in vitro reconstitution system to examine the properties of reconstituted chromatin composed of tail-less histones and a long DNA (106-kb plasmid) template. The tail-less nucleosomes did not aggregate at high salt concentrations or with an excess amount of core histones, in contrast with the behavior of nucleosomal arrays composed of nucleosomes containing normal, N-terminal tails. Analysis of our nucleosome distributions reveals that the attractive interaction between tail-less nucleosomes is weakened. Addition of linker histone H1 into the tail-less nucleosomal array failed to promote the formation of 30 nm chromatin fibers that are usually formed in the normal nucleosomal array. These results demonstrate that the attractive interaction between nucleosomes via histone tails plays a critical role in the formation of the uniform 30-nm chromatin fiber.     

Pulsed ion extraction from a hybrid plasma using a shunting arc discharge

A hybrid plasma is generated by combining a burst methane rf (195 kHz) plasma with a carbon shunting arc discharge. The shunting arc discharge triggers the rf methane plasma. As a result, the rf plasma is initiated over a wide range of ambient gas pressure from 0.045 Pa as a base pressure to a methane pressure of 1.26 Pa, at which the rf plasma is not self-ignited. When a target is immersed in the rf- and shunting arc-hybrid plasma, and a negative pulse voltage is applied to the target, carbon ions are extracted from the hybrid plasma. When the carbon shunting arc ionizes the methane gas, an rf plasma is initiated and the ionization of methane is significantly enhanced in the rf plasma. The plasma density in the hybrid plasma increases by a factor of approximately 5-9 compared to that of the shunting arc discharge.     

Heat transfer on tube bundles embedded horizontally in a liquid‐fluidized bed: 2nd report: On tube bundles of fundamental layouts including in‐line layouts

Heat transfer coefficients were measured on tube bundles of fundamental layouts including in‐line layouts embedded horizontally in a liquid‐fluidized bed. Tested tube layouts were single tubes, transverse single tube rows, longitudinal single tube rows, and in‐line arranged tube bundles. A total of 7 kinds of particles were used. Comparisons of the experimental data showed a good agreement with the heat transfer correlation developed for staggered layouts, when the average liquid velocity through each tube bundle was used as the reference velocity for the particle Reynolds number. Distribution of the local heat transfer coefficient was also investigated around tubes. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20245     

Pressure drop in liquid–solid circulating fluidized beds

An experiment was conducted to obtain data for pressure drop in risers of liquid–solid circulating fluidized beds, where two different risers (24 mm and 36 mm in diameter) were used. Tested particles were of glass and ceramics, and their diameter ranged from 2.10 to 4.95 mm. Water under ambient conditions was used as the fluidizing liquid. Pressure drop in the risers was measured using a reversed U‐tube manometer. Based on the experimental data, a calculation method was derived for predicting the pressure drop in the riser, which could reproduce almost all the data with an accuracy of ±20%. Furthermore, the effect of independent parameters was investigated on the pressure drop component ratios consisting of the total pressure drop. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20241     

Modulation Instability and Pattern Formation in Two-component Bose-Einstein Condensates

No Heading We investigate the dynamics of pattern formation caused by the modulation instability of two-component Bose-Einstein condensates in trapping potentials based on the numerical analysis of the coupled Gross-Pitaevskii equations. The modulation instability induced by the intercomponent mean-field coupling occurs in the out-of-phase fluctuation of the wave function and leads to the formation of multiple domains. We especially focus on the dimensional dependence of the dynamics by varying the aspect ratio of the trapping potential, finding the two-step dynamic process of the pattern formation due to the different time scales of the instability in the different spatial dimensions.PACS numbers: 03.75.Lm, 03.75.Mn     

Thermal neutron imaging with rare-earth-ion-doped LiCaAlF6 scintillators and a sealed Cf source

Thermal neutron imaging with Ce-doped LiCaAlF₆ crystals has been performed. The prototype of the neutron imager using a Ce-doped LiCaAlF₆ scintillating crystal and a position sensitive photomultiplier tube (PSPMT) which had 64 multi-channel anode was developed. The Ce-doped LiCaAlF₆ single crystal was grown by the Czochralski method. A plate with dimensions of a diameter of 50×2 mm² was cut from the grown crystal, polished, and optically coupled to PSPMT by silicone grease. The ²⁵²Cf source (<1 MBq) was sealed with 43 mm of polyethylene for neutron thermalization. Alphabet-shaped Cd pieces with a thickness of 2 mm were used as a mask for the thermal neutrons. After corrections for the pedestals and gain of each pixel, we successfully obtained two-dimensional neutron images using Ce-doped LiCaAlF₆.     

Cleaning of materials contaminated with metal oxides through supercritical fluid extraction with CO2 containing TBP

Studied was an application of supercritical fluid extraction (SFE) to cleaning of the materials contaminated with metal oxides. By using supercritical CO₂ including chemical complexes of tri-n-buthylphosphate (TBP) and HNO₃, lanthanide was recovered from oxide mixtures placed in a pressure vessel. The lanthanide oxide was dissolved with TBP-HNO₃ and extracted with TBP in supercritical CO₂. This cleaning method reduces volume amount of liquid waste arising from treatment of the contaminated materials. Being applied to a mixture of Gd₂O₃ and SrO, we found that Gd was selectively recovered and Sr was not found in the recovered solution. Gd was also selectively recoverd when a mixture of Gd₂O₃ and ZrO₂ was treated. This selective nature of decontamination is an additional advantage of the SFE with TBP-HNO₃ complex. This method would be applicable to the selective cleaning of materials contamined with radioactive oxides such as UO₂/PuO₂.     

Enhancement of arachidonic acid production by Mortierella alpina 1S-4

The effect of mineral addition on arachidonic acid (AA) production by Mortierella alpina 1S-4 was evaluated. At first, the addition of minerals such as sodium, potassium, calcium, and magnesium was examined in flask cultures, and then the addition of phosphorus with the optimal amounts of the minerals was investigated in a 10-L jar-fermenter. As a result, 1.5% soy flour medium with the addition of 0.3% KH₂PO₄, 0.1% Na₂SO₄, 0.05% CaCl₂·2H₂O, and 0.05% MgCl₂·6H₂O was found to enhance the AA yield 1.7-fold over that without mineral addition. When 1% yeast extract with the above mineral mixture was used, the AA yield was enhanced 1.35-fold over that without minerals. We also verified that an increase in the polar lipid content occurred in the case of only KH₂PO₄ addition, and that the above-mentioned increase in the AA yield was due to the minerals themselves, not a pH buffer effect.     

Task learning of a task robot in real space by using a learning system in virtual space

Reinforced learning by which a robot acquires control rules by trial and error has attracted considerable attention. However, it is quite difficult for robots to acquire control rules by reinforcement learning in the real space because many learning trials are needed to arrive at the control rules; the robot itself may lose control, or there may be safety problems with the control objects. In this paper we propose a method in which a robot in the real space learns a virtual task, after which the task is transferred from the virtual to the real space. The robot eventually acquires the task in a real environment. We show that a real robot can acquire a task in a virtual space with an input device, using the example of an inverted pendulum. Next, we verify that the acquired task in the virtual space can be applied to a real‐world task. We emphasize the utilization of the virtual space to effectively obtain the real‐world task. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(1): 38–47, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20968