An attempt was made to elucidate the effect of the terminal group on physical, rheological and

The use of TSDC analysis [1][2][3][4] for iced water has only been carried out by a limited number of researches. [5][6][7][8][9][10] Jeneveau et al. 6 found three major depolarizing current J peaks on J-Temperature (-170 --20˚C) curves, obtained at a heating rate (β) of 3.0˚C/min. Three peaks at -154˚C, -113˚C and -94˚C were found to have activation energies (Ea) of 20.2, 27.0 and 57.8 kJ/mol, respectively. Pissis et al. 7 reported three peaks at -148˚C with an activation energy (Ea) of 24.2 kJ/mol and at -111˚C and -48˚C with no Ea data obtained at β = 3.5˚C/min. They also later reported three peaks at -165˚C with Ea = 23.2 kJ/mol, at -154˚C with Ea = 29.9 kJ/mol and at -53˚C with Ea = 40.6 kJ/mol, obtained at β = 3.0˚C/min. 9 The peak temperature might be dependent on β, the polarizing temperature (Tp), the electrode utilized, and very small amounts of ionic contaminants. Herein, we report on results of the iced water structure, analyzed by TSDC, as a function of β and the polarizing voltage, with a consideration of the contaminant upon TSDC application to tap water samples. Experimental Water samplesSuper pure water (SPW), ion-exchanged water (IEW) and distilled water (DSW) were utilized. SPW was prepared by the ultra-filtration of DSW using acrylic micro-filter and ultrafilters. IEW was prepared by a Millipore apparatus. DSW was prepared by distilling tap water. The IEW was used as the standard for all experiments discussed in this paper. The main cation concentrations, pH values, electric-conductivities (EC) and dissolved oxygen concentrations (DO) are collected in Table 1. Cations other than Si 2+ (ca. 100 ppb for IEW, DSW) were found to be in negligibly small amounts (less than 2 ppb). Naturally, the electric-conductivity of IEW was smaller than that for DSW. However, that of SPW was slightly larger than that of IEW. The reason is not clear, but it might be related to the fact that the dissolved oxygen level of SPW is high. As can be seen in Table 1, IEW has an EC of 0.35 -0.39 µS/cm (25˚C) and a dissolved-oxygen concentration of 4.12 -5.13 ppm. The IEW was determined to contain Si 2+ , Fe 3+ , K + , Zn 2+ , Na + in concentrations of only 97, 0.51, 0.47, 0.12 and 0.05 ppb, respectively, without any detectable Mg 2+ and Ca 2+ . In order to examine the influence of various cations in the water on the TSDC profiles, the water samples containing 2 -100 ppm levels of K + , Li + , Na + , Mg 2+ and Ca 2+ were prepared by dissolving the corresponding hydroxides in the IEW. Guaranteed-grade deuterated water (HW, NMR use) was also used as a reference. TSDC measurements were also made on tap water for drinking (TWD, Takatsuki city) and two tap water samples for industrial use (TWI) (Takatsuki city, Tonegawa), which have much higher cation contents (see Table 1). Quantitative ion analyses (EC, pH and DO) for all water samples were carried out on an atomic-absorption spectrophotometer (Shimadzu Co., Ltd. AA-6400F, flame emission type), EC meter (Toa-Denpa Co., Ltd.), pH meter and DO meter (Horiba, Ltd.), respectivel...

ABSTRACT:As an extension of the previous studies [M. Tomokiyo et al., submitted to Sen-i Gakkaishz], an attempt was made to elucidate the intrinsic role of terminal groups in the hydrogen bonding formation and the existing state of water in poly(hexamethylene adipamide) (nylon 66) with different molar fraction of amino end group fN· (fN = [NH2]1([NH2] +[COOH])) For this purpose, the heat-pressed nylon 66 films were subject to infrared (IR) and tanfJ-t analyses and at the same time the films which absorbed !Owt% of water were subject to 1 H NMR measurements to determine relaxation time T 1 of water. Analyses on the change in the wave numbers of NH and CO stretching vibrations (K,NH• K,c0 ), the activation energy evaluated from the temperature dependence of K,NH and K,co and the activation enthalpy and entropy for C£. and C£b relaxations indicated that the stronger hydrogen bond is formed for nylon 66 with larger fN, which corresponds to the higher molecular packing density and higher activation energy for flow of the melt for these polymers. 1 H NMR revealed that water which penetrated into nylon 66 is composed of two electro-magnetically different species, one of which might be the ionized water by end groups, and those species are also composed of at least two components with shorter T1 (Tt,8 ) and with longer T1(T1.A). The existence of ionized water was supported by the pH measurement of water containing nylon 66. The both T1 were shorter for nylon 66 with lower fN, denoting that the nylon interacts more strongly with water, which is quite comparative to the facts that nylon 66 with low fN exhibits the lower resistance to the penetration of water for this polymer. These facts leaded to an idea that water in polyamide is ionized by the polar terminal end groups and based on this idea a tentative hydrogen bonding for nylon 66 with high and low fN ( Authors have already pointed out the importance of the balance of terminal groups of poly(hexamethylene adipamide) (nylon 66) in the water adsorption behavior, the rheological and thermal properties and the crystallization kinetics of the polymers 1 and the fiber structure formation during its melt-spinning process. 2 All these data have revealed that 1) nylon 66 with higher molar fraction of amino end group fN is more resistant to the water adsorption, lowers the crystallization rate but exhibits the lower molecular mobility brought about by an increase in the activation energy for flow of the polymer melt and 2) the nylon 66 with larger fN is fabricated into the fiber having amorphous region characterized by stronger cohesive nature of molecular chains. All result seems to support the idea that nylon 66 with highfN has inherently stronger molecular interaction in the amorphous region to hinder the structural change induced by heat and humidity to some extent. However, the essential reason for the above phenomena has not been fully understood yet. Since polyamide has a potential ability to form hydrogen bond between amide groups (amino hydrogen and carboxyl groups) ...

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Introduction Animal‐model experimental systems capable of reflecting the effects of devices for continuous renal replacement therapy (CRRT) on living organisms are limited; thus, aimed to construct an animal model of AKI‐CRRT using pigs. Methods Pigs were subjected to renal artery ischemia–reperfusion injury (IRI) and then to a maximum of 24 h of continuous hemodiafiltration (CHDF)‐type CRRT. Results Post‐IRI, pigs' creatinine levels rose threefold, and they exhibited 24 h of anuria and clear aggravation of oxidative stress, demonstrating successful induction of AKI for CRRT. Post‐CRRT, no significant changes in their vital signs or hematological parameters were observed. Creatinine and blood urea nitrogen clearance, as well as suppression of increases in oxidative stress, were also confirmed. Conclusion We believe that the use of our model can enable the preclinical evaluation of the effects of under‐development CRRT devices on living organisms under conditions similar to those encountered in an actual clinical setting.