Biography:

In the past K. Onda has collaborated on articles with H. Noguchi and F.C. Brownfoot. One of their most recent publications is Gas absorption accompanied by complex chemical reactions — III Parallel chemical reactions. Which was published in journal Chemical Engineering Science.

More information about K. Onda research including statistics on their citations can be found on their Copernicus Academic profile page.

K. Onda's Articles: (6)

Gas absorption accompanied by complex chemical reactions — III Parallel chemical reactions

AbstractGas absorption accompanied by the parallel chemical reactions is discussed from the view-point of the film theory. The approximate solutions for the ratio Φ are derived by the same method described in our previous papers and compared with the analytical or numerical solutions for several cases. The difference of the ratio Φ between the approximate and the exact solutions is only a few per cent.

Gas absorption accompanied by complex chemical reactions - II Consecutive chemical reactions

AbstractBased upon the film theory, the approximate solutions for gas absorption accompanied by two consecutive chemical reactions of the forms γAA+γBB→γCC+ Product,γA′A′+γCC→γCC→γBB and γAA+γBB→γCC,γAA+γ′CC Product, are derived and compared with the numerical solutions. For the case of equal diffusivities, the approximate and numerical solutions agree with each other within a few per cent.

Gas absorption accompanied by complex chemical reactions-IV: Unsteady state

AbstractFor gas absorption accompanied by (m,n)-(p,q)-th order reversible, consecutive and parallel chemical reactions, the approximate solutions based on the penetration and surface renewal theories are derived under the condition of equal diffusivities, and compared with the approximate solution based on the film theory to manifest the generalized solution being suitable for three theories. For the case of reversible chemical reaction, the approximate solution based on the penetration theory is compared with the numerical solution to examine the accuracy of Hikita and Asai's approximation in the unsteady state. It is found that the division of the approximate solution from the numerical solution is only a few per cent.

Time-resolved SFG study of formate on a Ni(111) surface under irradiation of picosecond laser pulses

AbstractTime-resolved sum-frequency generation spectroscopy was carried out on a deuterated formate (DCOO) adsorbed on Ni(1 1 1) surface to investigate the surface reaction dynamics under instantaneous surface temperature jump induced by the irradiation by picosecond laser pulses. The irradiation of pump pulse (800 nm) caused the rapid intensity decrease of both CD and OCO stretching modes of bridged formate on Ni(1 1 1). Different temporal behaviors of intensity recovery between these two vibrational modes were observed, i.e., CD stretching mode recovered faster than OCO. This is the first result to show that the dynamics of adsorbates on metals strongly depends on the observed vibrational mode. From the results of temperature and pump fluence dependence, we concluded that the observed intensity change was not due to the decomposition or desorption, but was induced by a non-thermal process.

Soluble endoglin production is upregulated by oxysterols but not quenched by pravastatin in primary placental and endothelial cells

AbstractIntroductionPreeclampsia is a serious pregnancy complication. Soluble endoglin (sEng) is released from the placenta and contributes to the maternal endothelial dysfunction seen in preeclampsia. Recently oxysterols, which activate the Liver X Receptor (LXR), have been implicated in producing sEng, by upregulating matrix metalloproteinase-14 (MMP14; cleaves endoglin to produce sEng) and down-regulating tissue inhibitor of metalloproteinase-3 (TIMP-3; inhibitor of MMP14). The functional experiments in that study were performed on JAR cells (human choriocarcinoma cell line) and placental explants.MethodsWe characterized LXR in severe preeclamptic placentas, and assessed whether oxysterols increase release of sEng from primary human umbilical vein endothelial cells (HUVECs), primary trophoblasts and placental explants. Given pravastatin is thought to block oxysterol production and inhibit the LXR, we examined whether pravastatin reduces sEng release.ResultsLXRα and β were localized to the syncytiotrophoblast and villous tips and were significantly up-regulated in preeclamptic placenta. Oxysterols upregulated sEng production in HUVECs and placental explants although the increases were far more modest than that recently reported. Oxysterols did not upregulate sEng in primary trophoblasts. Furthermore, mRNA expression of MMP14 and TIMP-3 were not altered by oxysterols in any tissue. Surprisingly, pravastatin did not decrease oxysterol-induced upregulation of sEng.DiscussionLXR is up-regulated in preeclamptic placenta. Oxysterols upregulate sEng production from human tissues, but the increase is modest, suggesting this may not be the main mechanism for the very significant elevations in sEng seen in preeclampsia. Pravastatin does not decrease sEng production.ConclusionOxysterols modestly up-regulate sEng production which is not quenched by pravastatin.

Changes in parathyroid hormone-related protein concentrations in bovine milk from the early stage of lactation

AbstractThe concentration of parathyroid hormone-related protein (PTHrP) in the blood of healthy animals is extremely low. However, milk contains a relatively large amount of PTHrP, and the changes in its levels in the early stages of lactation in cows remain unclear. To understand the characteristics of parturient changes in milk PTHrP content and the biological implications thereof, changes in milk PTHrP concentrations were measured at 7 time intervals between parturition and 21 days postpartum in 8 primiparous and 8 multiparous Holstein cows. Based on these results, milk samples were collected from 47 primiparous and 66 multiparous Holstein cows at 3 days postpartum to investigate the relationship between milk PTHrP concentration and the variables of cow age, milk yield, and milk calcium concentration. Milk PTHrP concentration in both parity groups was found to be lowest on the day of parturition (primiparous, 3.1±0.5 nM and multiparous, 1.6±0.3 nM) but to significantly increase on day 14 of lactation in primiparous cows (6.2±0.8 nM) and day 7 of lactation in multiparous cows (4.1±0.2 nM). Comparison of the 2 groups revealed that milk PTHrP concentrations in primiparous cows were higher than those of multiparous cows in the first 3 days of lactation. Although a significant negative relationship was found between milk PTHrP concentration and both age (r=−0.65) and milk calcium concentration (r=−0.19) at 3 days postpartum, no significant correlation was found between milk PTHrP concentration and milk yield. The study thus identified 3 unique characteristics of milk PTHrP concentration in the early stages of lactation: milk PTHrP concentration is higher in primiparous than multiparous cows, milk PTHrP concentration is lower in colostrum than later milk, and the difference in milk PTHrP concentration between primiparous and multiparous cows at 3 days postpartum is more strongly influenced by age than milk yield.

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