Saltiness and Acidity: Detection and Recognition Thresholds and Their Interaction Near the Threshold

ABSTRACT:  Interaction of saltiness and acidity at the threshold level was studied employing 35 to 40 young female panelists. As a 1st step, the detection and recognition thresholds of salt, rice vinegar, and rice black vinegar have been measured for each panelist. To investigate the above interaction, the thresholds have been again measured for each panelist of salt, but this time, vinegar at half the concentration of each panelist's detection threshold was added to the salt solution. Similar measurement has been performed for vinegars with salt at half the concentration of each panelist's detection threshold. The data analysis has been done in 2 ways, namely, (1) by using Student's t -test to detect the significant difference in average between the data with and without the added ingredient and (2) detecting significant deviations from zero in the individual shifts in 2 sensory tests among panelists who participated in the 2 measurements. In doing that, a conversion of the scale was necessary to correct the systematic skewness existing in the original data. As a result, both the detection and recognition thresholds of salt were decreased with the existence of the added vinegar ingredient ( P < 0.001). This tendency was more pronounced with rice black vinegar than with rice vinegar. On the contrary, no significant changes in the threshold of both detection and recognition were observed when salt at the half concentration of the detection threshold was added to rice vinegar. The interaction therefore was found to be asymmetric.     

Review of Functional Studies of Beverage Components Acting on the Recombinant GABAA Neuroreceptor, and Na+/Glucose Cotransporter-Response Using the Xenopus Oocyte Expression System and Electrophysiological Measurements

Beverages such as teas, coffee, cacao, and liquors are produced in large quantities and consumed all over the world. Natural components from beverages affect neurotransmitter receptors, especially the GABA_A receptors, which are involved in defining mental state and therefore have role in stress management in modern society. These components of beverages modulating the responses of GABA_A receptors or other neurotransmitter receptors that affect mental state linked to stress and mood can easily be detected by expressing the receptors in Xenopus oocytes and making voltage-clamp electrophysiological measurements. This approach could be extended to detect food-components, which are functionally active on various transporters such as Na⁺/glucose cotransporters operating in the small intestines to transport glucose into blood, which are inhibited by (+)-catechin and its derivatives in teas. Using this technique, it has become apparent that beverages for stress and mood management must have long-chain normal alcohols but short-chain esters, and phenol derivatives having low numbers of OH^- or phenol groups in addition to fragrant compounds such as geraniol, linalool, cis-jasmone, methyl jasmonate, 1-octen-3-ol, myrcenol, terpinen-4-ol and ethyl phenyl propanoate. The technique could also be used easily to assess the toxicity of food-components to cells, as was reported for saponin and tannic acid which produce large electrical responses in the oocyte. Further, (+)-catechin and its derivatives, and aqueous extracts of coffee, green tea, oolong tea and black tea, dose-dependently produce nonspecific currents, suggesting that high concentrations of these beverages may be detrimental to health.     

Novel quick backup function for dispersed power source employing AC/DC converter

In this paper, the authors present the system configuration and control scheme of a dispersed power source equipped with quick backup function, which acts as a dispersed power source when no fault exists in a commercial power network and functions as a backup power supply in case of a fault of the network. If a fault, such as a voltage interruption on the network, occurs, the dispersed power source disconnects critical loads from the network in an instant and continues supplying power to the critical loads. We also discuss the method of disconnecting a power network sufficiently quickly when some fault occurs on the network, adopting non‐gate‐turn‐off devices such as thyristors for the AC interconnecting switches. Since it takes only 2 ms to disconnect the loads from a faulted network, there are no negative effects on the loads. Simulations and experimental tests confirm the practicability of the proposed method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 74–81, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20700     

Hydrolysis of β-glucosyl ester linkage of p-hydroxybenzoyl β- -glucose, a chemically synthesized glucoside, by β-glucosidases

To investigate the hydrolysis of glucosyl esters by β-glucosidase, p-hydroxybenzoyl β- -glucose (pHBG) was chemically synthesized. The hydrolytic activity of some β-glucosidases for pHBG was compared to that for p-nitrophenyl β-glucoside (pNPG). The Clavibacter michiganense and Flavobacterium johnsonae enzymes could hydrolyze pHBG and steviol glycosides which are natural glucosyl esters. The commercial β-glucosidase originating from Caldocellum saccharolyticum also hydrolyzes pHBG despite having no activity for steviol glycosides. The β-glucosidase from Aspergillus niger cleaved the glucosyl ester linkage much more weakly than the glucosidic linkage. The pH-activity profile for the hydrolysis of pHBG was similar to that of pNPG by the C. saccharolyticum β-glucosidase. The similar profiles for these substrates suggested that the active site for the glucosyl ester chemically resembles that for glucoside with respect to catalysis. Kinetic analysis of the C. saccharolyticum β-glucosidase for mixed substrates of pHBG and pNPG showed that the hydrolysis of pHBG competed with that of pNPG. This result indicated that there is only one active site for both the glucosyl ester and glucoside. Mass spectroscopic analysis of the hydrolysates of pHBG in H₂¹⁸O suggested that β-glucosidase hydrolyzes glucosyl esters between the anomeric carbon of glucose and the carbonyl oxygen, not between the carbonyl carbon and the carbonyl oxygen.     

Stability of Two-Component Bose-Einstein Condensates in Traps

Static and dynamic stabilities of two-component Bose-Einstein condensates trapped in harmonic potentials are studied. Using the variational method, we obtain the static stability condition and the phase separation condition. They are expressed as functions of the particle numbers and the s-wave scattering lengths. We find that the interaction between the different species of atoms (simply, interspecies interaction) has significant effects on the stability of each condensate. The instability of the ground state is explained in terms of the lowering (softening) of the collective excitation energies. We investigate the low-lying excitations and the possibility of their softening by use of the Gaussian ansatz and the sum-rule approach.     

中厚板产品的最新研究

近十年来 ,有关中厚板的主要研究项目一直是随着市场的需求而进行的。由于市场对产品的安全性、环保概念、降低成本等因素的要求更加严格、品种要求更加多样化 ,用中厚板制成的焊接结构的设计技术趋于统一。中厚板的研究项目包括 :(1 )强化处理和韧化处理的冶金性能 ;(2 )ＴＭＣＰ(热机械加工控制技术 )和复杂的微合金技术的结合 ,提高了性能 ,缩短了工艺 ;(3)ＨＡＺ(热影响区 )的韧性控制 ;(4)高强度钢与不用预热处理的可焊性焊接法得优化组合 ;(5)“低硫和酸性”环境下的抗腐蚀性能 ;(6)合金钢 ;(7)断裂、疲劳和塑性变形的测试、控制和计…     

Plastic split alignment sleeves for single-mode fiber connection ofMU- and SC-type ferrules

Split alignment sleeves for the single-mode optical-fiber connection of MU and SC-type ferrules were successfully fabricated for the first time with a precise injection-molding technique using a thermosetting epoxy resin. The optimum inner radii of the plastic sleeves were determined with a view to realizing both suitable gauge retention forces for the ferrules and a small fiber offset of 1 μm between them. The adapters incorporating the plastic sleeves showed excellent performance with an average connection loss of 0.09 dB and a return loss of >50 dB     

Fundamental investigation of subsurface damage in single crystalline silicon caused by diamond machining

Single crystalline silicon was plunge-cut using diamond tools at a low speed. Cross-sectional transmission electron microscopy and laser micro-Raman spectroscopy were used to examine the subsurface structure of the machined sample. The results showed that the thickness of the machining-induced amorphous layer strongly depends on the tool rake angle and depth of cut, and fluctuates synchronously with surface waviness. Dislocation activity was observed below the amorphous layers in all instances, where the dislocation density depended on the cutting conditions. The machining pressure was estimated from the micro-cutting forces, and a subsurface damage model was proposed by considering the phase transformation and dislocation behavior of silicon under high-pressure conditions.     

The inhibitory effects of components from a brown alga,Eisenia arborea,on degranulation of mast cells and eicosanoid synthesis

The anti-allergic effect of an edible brown alga, Eisenia arborea, was investigated by determining the anti-degranulation activity on RBL cells or KU812 cells and the inhibitory effects on enzymatic activities involved in eicosanoid (leukotoriene and prostaglandin) synthesis. When the stimulated cells were treated with a M/C (methanol:chloroform = 1:2, v/v) extract of the alga, the histamine release of the cells was suppressed in a dose-dependent manner, and eicosanoid release from the cells was also strongly inhibited. Furthermore, the M/C extract and six phlorotannins (eckol, 6,6′-bieckol, 6,8′-bieckol, 8,8′-bieckol, phlorofucofuroeckol-A, phlorofucofuroeckol-B) derived from the extract inhibited enzymatic activities responsible for eicosanoid synthesis. This is the first report of the enzymatic activity inhibition by the phlorotannins 6,6′-bieckol, 6,8′-bieckol and PFF-B. Since histamine and eicosanoids are known to mediate the allergic reaction, inhibition of these mediators and enzymatic activities could be responsible for the anti-allergic effect of the alga.