Design and synthesis of oligosaccharides that interfere with glycoprotein quality-control systems

Calnexin (CNX) and its soluble homologue calreticulin (CRT) are lectin-like molecular chaperones that help newly synthesized glycoproteins to fold correctly in the rough endoplasmic reticulum (ER). To investigate the mechanism of glycoprotein-quality control, we have synthesized structurally defined high-mannose-type oligosaccharides related to this system. This paper describes the synthesis of the non-natural undecasaccharide 2 and heptasaccharide 16, designed as potential inhibitors of the ER quality-control system. Each possesses the key tetrasaccharide element (Glc1Man3) critical for the CNX/CRT binding, while lacking the pentamannosyl branch required for glucosidase II recognition. These oligosaccharides were evaluated for their ability to bind CRT by isothermal titration calorimetry (ITC). As expected, each of them had a significant affinity towards CRT. In addition, these compounds were shown to be resistant to glucosidase II digestion. Their activities in blocking the chaperone function of CRT were next measured by using malate dehydrogenase (MDH) as a substrate. Their inhibitory effects were shown to correlate well with their CRT-binding affinities, both being critically dependent upon the presence of the terminal glucose (Glc) residue.     

PERFORMANCE OF A PRESSURIZED TWO-STAGE FLUIDIZED GASIFICATION PROCESS FOR PRODUCTION OF LOW-BTU GAS FROM COAL CHAR

A two-stage pressurized fluidized-bed gasification process has been developed to produce low-heating value gases from coal char. The reactor was 0.075 m id. and 1.4 m long, and gasification experiments were conducted under pressures up to 790 kPa and at temperatures up to 1323 K. A partition disc was used to divide the fluidized bed into two stages, using the first stage as a partial combuster and gasifier and the second stage as a gasifier. The disc was designed to control compositions of coal char particles in both stages so that the heat required for the endothermic gasification reaction in the second stage can be provided by the heat of combustion in the first

For conditions examined here, the disc with an opening ratio of 40° was found to give optimum distribution of the char particles in both stages without ash agglomeration. It was also shown that all oxygen gas was completely consumed within the first stage

The heating value of the product gas increased with the char feed rale. However, there may be an oplimum Teed ratio of char and sand-particles since the higher char feed rate causes more frequent ash agglomeration as well as less carbon conversion     

High‐sensitivity PEA system with dual‐polarity pulse generator

The pulsed electroacoustic (PEA) method has been widely used to observe space charge distributions in various solid dielectric materials. The sensitivity of the conventional PEA system is around 1C/m³. When the charge density is less than 1C/m³, however, it is difficult to obtain an accurate result because the signal due to the Maxwell stress becomes comparable with the signal to be measured. The Maxwell stress is generated by applying the pulsed electric field to the dielectrics, and independent from the existence of either induced charges by DC bias voltage or internal charges. In order to eliminate the influence of the Maxwell stress, we have developed a new PEA system with a dual‐polarity pulse generator. The system allows measurement space at a charge density of around 0.03C/m³. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 1– 7, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20496     

Generation,growth, shrinkage,and dispersion of Au agglomerates in Si during the annealing of supersaturated substitutional Au

Si samples homogeneously pre-indiffused with Au atoms at a concentration 7.5 × 10¹⁶ atoms/cm³ were heat treated at 900 °C for 22.5, 90, 360, and 1,440 h to generate Au agglomerates during the out-diffusion process of supersaturated high-temperature substitutional Au. The number of Au atoms in all of the agglomerates in the regions 8–22, 22–36, 36–50, and 50–64 μm from the surface were measured by secondary ion mass spectrometry, and the change of their distributions during annealing was obtained. As a result, agglomerates containing (1–3) × 10⁵ Au atoms were initially generated with a concentration of 1.1 × 10¹⁰ agglomerates/cm³ at a short annealing time. The generated agglomerates grow, shrink, and disperse with the decrease of the supersaturation of the surrounding Au concentration, that is, with increase of annealing time. The boundary Au concentration for changing from growth to shrinkage of the agglomerates is (3–5) × 10¹⁵ atoms/cm³. The agglomerates grow and contain until about 2.3 × 10⁶ atoms. The agglomerates disperse and finally disappear as the surrounding Au concentration decreases to its thermal equilibrium value with continued annealing. It is difficult to explain the continuous generation, growth, shrinkage, and dispersion of the agglomerates during annealing using the usual theoretical treatment of agglomeration of supersaturated solutes in solids.     

Robust grasping strategy for assembling parts in various shapes

In a robotic cell, assembly robots have to grasp parts in various shapes robustly and accurately even under some uncertainties in the initial poses of the parts. For this purpose, it is necessary to develop a universal robotic hand and robust grasping strategies, i.e. finger motions that can achieve planned grasping robustly against the initial pose uncertainty of parts. In this paper, we propose a methodology to plan robust grasping strategies of a universal robotic hand for assembling parts in various shapes. In our approach, parts are aligned toward planned configurations during grasping actions, and the robustness of grasping strategies is analyzed and evaluated based on pushing operation analysis. As an application example, we plan robust grasping strategies for assembling a three-dimensional puzzle, and experimentally verify the robustness and effectiveness of the planned strategies for this assembly task.     

Convenient Synthesis of Mesoporous Aluminosilicates by Using Pre-heated Sodium Aluminosilicate Gel

Hydrothermally stable Al-MCM-48 with variety of Si/Al ratios and Al-MCM-41 with tunable pore sizes were successfully obtained from pre-heated aluminosilicate gel precursor. They showed the higher acid strength and hydrothermal stability comparing with conventional ones. Thus, this synthetic strategy offers a straightforward and convenient access to mesoporous aluminosilicates with zeolite-like acidity and stability.     

Time-dependent variation of the target mode in reactive sputtering of Al-O2 system

Reactive sputtering techniques have been widely used for forming compound thin films. In this study, the time-dependent variation of the target mode of an Al-O₂ system was investigated by measuring the target voltage for various reactive O₂ gas flow ratios and presputtering (i.e., sputtering in pure Ar gas to clean the target surface) times. The Al target remains in metallic mode for a certain period of time after being exposed to an Ar-O₂ plasma before it begins to be oxidized. This period increases with decreasing O₂ flow ratio and with increasing the presputtering time. It is considered that the period is caused by the gettering of O₂ gas by Al films deposited on the substrate and the chamber wall during presputtering.     

Adaptive Control of Partially Known Systems and Application To Active Suspensions

In this paper, an adaptive control method is proposed for systems whose structures can be divided into a known part and an unknown part. A non‐adaptive control design, such as H∞ control design can be introduced into the known part of the system, and adaptive control can cope with the unknown part to realize the property designed by non‐adaptive control. This is achieved by means of backstepping. This method is applied to the control design of an active suspension system for a railway vehicle, which is divided into two parts: a main car body part and an actuator part. Some simulation results of the control system designed using H∞ control for the body part and adaptive control for the actuator part are provided.     

Basic Characteristics of Cycloconverter for Linking Commercial and High-Frequency Distribution Lines

A new method to improve the power factor and current waveform on the commercial ac system is proposed. The frequency of a local distribution line in a factory or a chemical plant is made high, up to about 500 Hz. The local distribution line is linked directly to the commercial line by using a cycloconverter operating in circulating current mode. Quasi-sinusoidal current with unity displacement factor is realized on the commercial line side regardless of the consumed power by loads. The system configuration and the basic principle of operation of the cycloconverter for linking both lines are described. The influence of system parameters on the operation limit is investigated based on the power equilibrium constraints. Experimental results obtained in the 5.2KVA laboratory system show the validity of the proposed system.