EFFECT OF HIGH PRESSURE ON THE ACCUMULATION OF IMP AND ON THE STABILITY OF AMP DEAMINASE IN RABBIT SKELETAL MUSCLE

This study evaluated the effect of high pressure on rabbit skeletal muscle, specifically on the production of inosinic acid (IMP), one of “umami” components, and on the activity of adenosine triphosphate (AMP) deaminase, which plays a role in the conversion of AMP to IMP. By increasing the pressure (0.1 to 300 MPa), nucleotide analysis showed that IMP content in muscle increased instantly with a concomitant decrease in ATP content. The IMP content of muscle at 300 MPa was approximately 15% higher than with lower pressures (0.1–200 MPa) when stored for 1 week at 4C after pressurization. These results suggested that the metabolism of nucleotides in muscle was not significantly impaired by pressure treatment. At 300 MPa, AMP deaminase maintained approximately 70% of the activity at 0.1 MPa. In contrast, the activity of purified AMP deaminase was completely lost at 200 MPa, and irreversible conformational changes were observed by in situ fluorescence spectroscopy. These results indicated that purified AMP deaminase was irreversibly denatured under pressure as high as 300–400 MPa.     

DNA ANALYSIS FOR IDENTIFICATION OF FOOD-ASSOCIATED FOREIGN SUBSTANCES

To identify food‐associated foreign substances, a DNA analysis consisting of 18S rDNA sequencing and homology search analysis has been developed. In this method, we designed universal primer pairs for specific amplification of animal and plant 18S rDNA and constructed an original DNA database storing partial 18S rDNA sequences of 222 organisms commonly used for culinary purposes. In the model experiments, food materials were successfully identified, indicating that our DNA analysis method can be practically applied to the identification of food‐associated foreign substances. It is also expected that this method complements conventional morphological and compositional analysis, leading to more accurate and reliable identification of food‐associated foreign substances.     

成型冶金灰脱硫剂对烟气脱硫及其再生的研究

冶金灰(MD)因含大量的金属氧化物而有很强的脱硫能力.但是,MD颗粒细小,易被气流吹走,不能直接应用.必须将MD成型为有一定尺寸和足够机械强度后才能采用.研究了成型冶金灰脱硫剂(DSMD)的成型、脱硫和再生.实验结果指出,首先将诸如粘土,水玻璃,聚磷酸钠等粘结剂,水和MD混合,混合质量比MD:粘土:水玻璃:聚磷酸钠:水为100:3.3:3.3:3.3:5.0,然后将混合粉末压制成圆柱状块体,最后在973 K时结烧3 h.DsMD在烟气脱硫(FGD)过程中的脱硫率和MD相近,而且经过几次连续的脱硫-再生循环后,脱硫率仍保持稳定.此外,当DSMD未被贯透和DSMD的硫容量到达约5～6 mol/kg(＞773 K)之前,烟气出口处的H2S浓度可保持在小于10 mg/m3的水平.     

A Low‐Speed,High‐Torque Motor Drive Using a Modular Multilevel Cascade Converter Based on Triple‐Star Bridge Cells (MMCC‐TSBC)

This paper provides an experiment‐based discussion on a modular multilevel cascade converter based on triple‐star bridge cells (MMCC‐TSBC) for a low‐speed high‐torque motor drive. The TSBC is a direct ac‐to‐ac power converter capable of achieving bidirectional power flow as well as drawing and feeding three‐phase sinusoidal input (supply‐side) and output (motor‐side) currents with any power factor at both sides. This paper discusses active dc‐capacitor‐voltage control applied to the low‐speed, high‐torque motor drive. A specially designed downscaled system combining a 320‐V, 38‐Hz, 6‐pole, 15‐kW induction motor with a 400‐V, 15‐kW TSBC is constructed and tested to confirm the validity of the motor drive. Experimental waveforms obtained from the downscaled system confirm stable operation with the rated load torque across a range from a standstill to the rated speed, including satisfactory start‐up performance.     

Optimizing the Enzymatic Maceration of Foliole Purée from Hard Pieces of Hearts of Palm (Euterpe edulis Mart.) using Response Surface Analysis

Response surface analysis was applied to investigate modifications in viscosity of foliole purée treated with commercial enzyme preparations high in cellulase and endopolygalacturonase (pectinase) with changes in enzyme concentration (0.3–1.2%), incubation time (3.3–6.7 hr) and temperature (40–50°C). Foliole purée was obtained by trituration of hard pieces of hearts of palm (Euterpe edulis) and incubated in a rotating agitator. After treatment with 0.81% cellulase for ～5 hr at 50°C, a fourfold reduction in viscosity was found relative to a control sample. The minimum viscosity for this treatment was within the experimental range investigated. Optimized experimental conditions for treatment with pectinase however were outside the experimental range. The application of the cellulase preparation to the purée resulted in a 10% increase in yield of edible palm.     

Self-propagating high-temperature synthesis of AlN in a graphite crucible in air by mechanical activation

Powders of Al and C were mixed in a molar ratio of Al :C = 3:1 and were then ground in a planetary ball mill. When the thus mechanically activated mixtures were transferred into a graphite crucible and exposed to air, they spontaneously ignited and self-propagating high-temperature synthesis took place in two successive steps. The products were sliced along the depth direction and examined by X-ray diffraction. Depending on the depth of the crucible, aluminium nitride, aluminium carbide, aluminium oxynitride, aluminium oxycarbide and alpha alumina were detected. From measurements of the lattice constant, it was found that aluminium nitride with a 97% purity could be obtained at the bottom of the graphite crucible. This revised version was published online in November 2006 with corrections to the Cover Date.     

用氧化镁铝热还原原位产生的镁蒸气改善铁水脱氧效率

提出了一种用氧化镁铝热还原原位产生的镁蒸气进行铁水脱氧的新方法.建立了反应模型来研究控速机理和镁蒸气的脱氧效率.模型计算结果显示,要获得高脱氧效率,必须控制喷吹气泡中的镁蒸气压力.     

EFFECT OF HIGH PRESSURE TREATMENT ON CYTOPLASMIC 5'-NUCLEOTIDASE FROM RABBIT SKELETAL MUSCLE

We investigated the effect of high‐pressure treatment on the properties of cytoplasmic 5′‐nucleotidase (NT), which converts inosine monophosphate (IMP) into inosine. After pressure treatment at 400 MPa, the activity of purified IMP‐NT remained at almost 100%, but the activity of partially purified adenosine monophosphate (AMP)‐NT decreased to about 40%. These data suggest that there is a difference in the pressure stability between the enzymes. In situ fluorescence spectroscopy of IMP‐NT under pressure showed that its pressure‐induced denaturation was reversible. When the pressure was reduced from the highest pressure to ambient pressure, hysteresis was observed. This suggests that high pressure treatment may lead to a partial change in the affinity of the subunits for each other once they have dissociated. The activities of IMP‐NT and AMP‐NT extracted from pressure‐treated muscles decreased remarkably between 250 and 450 MPa, but IMP‐NT was more stable than AMP‐NT.     

Effect of stress ratio on fatigue lifetime and crack growth behavior of WC–Co cemented carbide

Two types of fatigue tests, a rotating bending fatigue test and a three- or four-point bending fatigue test, were carried out on a fine grained WC–Co cemented carbide to evaluate its fatigue crack growth behavior and fatigue lifetime. From successive observations of the specimen surface during the fatigue process, it was revealed that most of the fatigue lifetime of the tested WC–Co cemented carbide was occupied with crack growth cycles. Using the basic equation of fracture mechanics, the relationship between the fatigue crack growth rate (da/dN) and the maximum stress intensity factor (K_max) was derived. From this relation, both the values of the threshold intensity factor (K_th) and the fatigue fracture toughness (K_fc) of the material were determined. The fatigue lifetime of the WC–Co cemented carbide was estimated by analysis based on the modified linear elastic fracture mechanics approach. Good agreement between the estimated and experimental fatigue lifetimes was confirmed.     

A High Immersive Telexistence System of the Moving Object with Full Circumference Image and Inertial Force Presentation

Currently, the remote control such as the bilateral control which enables transmitting the multimodal information has been studied. However, remote control has not been reached while perceiving the wind, gravity, and the condition of the ground on the moving object at the remote place. When it is possible to perceive the external force applied to the moving object, it is possible to perform an appropriate operation sensuously according to a remote place such as a slope or a gravel road. Therefore, we propose a high immersive telexistence system with head mounted display and the six‐axis motion base which enables transmitting the inertia and force information of the moving vehicle, and 360‐degree image of moving object's surroundings at real‐time.