The pore-wall chemistry of activated carbon fiber (ACF) was controlled by heating in Ar and H2. The ACF
structures were characterized from various levels, and interaction of water vapor with the micropores of ACF
was directly measured by calorimetry. Two kinds of pitch-based ACFs with different pore widths (w) (P5, w
= 0.7 nm, and P20, w = 1.0 nm) were used. P20 was treated at 1273 K in a gas flow of Ar or H2 for 1 h to
modify its surface properties. Adsorption isotherms of water on the two ACFs at 303 K showed different
features, which are possibly caused by the pore width difference. The surface modification by the heat treatment
of P20 changed its pore structure, leading to different water adsorption behavior. The mechanisms of water
adsorption and desorption can be discussed through the differential or integral heat of water adsorption or
desorption. Water adsorbs on the functional groups located at the surface of P20 with an adsorption heat
comparable to the heat of condensation at relatively low P/P
0, causing the cluster formation of water molecules.
The removal of such functional groups by heat treatment decreases the adsorption heat at low pressure. The
differential heat abruptly increases at filling in all cases, indicating a structural formation of water from a
clustered form to a highly ordered form.
The aim of the present study was to investigate the relationship between assisted reproductive technology procedures, the morphology of the basal plate of placentas, and amount of bleeding in deliveries. Fifty-five whole placentas (fresh-embryo transfer in the in vitro fertilization cycle [n = 6], frozen-thawed embryo transfer in the natural cycle [n = 13] or in the hormonal cycle [n = 10], and age-matched spontaneously conceived pregnancies [n = 26]) were retrospectively enrolled and histologically analyzed. The whole placentas were stored in our pathological division among 512 singleton pregnancies with vaginal deliveries (34-41 weeks of gestation) at Hamamatsu University Hospital. The morphology of the placental basal plate was examined using Azan staining. A total of 20 digital images (each 0.53 mm(2)) of microscopic fields were analyzed per placenta to measure the mean values of the vertical maximum thickness of Rohr and Nitabuch fibrinoid layers and % loss of decidua. The thickness of Rohr fibrinoid layer and % loss of decidua were significantly higher in the frozen-thawed embryo transfer in the hormonal cycle group than in the frozen-thawed embryo transfer in the natural cycle and spontaneously conceived pregnancy groups (each P < .01). The z scores for both the thickness of Rohr fibrinoid layer and % loss of decidua positively correlated with those for the amount of bleeding in deliveries (P < .05 each). Assisted reproductive technology procedures changed the morphology of the placental basal plate, suggesting a possible association with an increase in the amount of bleeding in deliveries.
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