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A systematic study was performed on the dynamic viscoelastic properties of N-methylpyrrolidone (NMP) solutions of poly(vinylidene fluoride) (PVDF) samples with a wide range of weight average molar masses (Mw) from 140 to 3300 kg mol−1 over a temperature range of −24 to 35 °C in the dilute to semidilute concentration (c) regime in this study. In previous studies under extremely dilute conditions, it was confirmed that PVDF molecules behave as isolated highly elongated rigid rods, and the average particle length (⟨L⟩) and diameter (⟨d⟩) for different PVDF samples were precisely determined. The fundamental viscoelastic parameters used to analyze the dynamics of PVDF molecules dissolved in NMP were precisely determined, including the zero-shear shear viscosity (η0), the steady state compliance (Je), the average relaxation time (τw), and the activation energy (E*v) of τw in this study. E*v increased stepwise above c values corresponding to the reciprocal of the intrinsic viscosity ([η]−1) for different solutions, independent of Mw, showing that contact or the formation of entanglements between PVDF molecules causes the increase in E*v. Je−1 was found to be proportional to the number density of PVDF molecules (ν = cNAMw−1, where NA denotes the Avogadro constant) over the entire investigated v range, irrespective of Mw and the presence of entanglements between PVDF molecules. The reduced specific viscosities, ηspNA⟨L⟩3(Mw[η])−1, were reasonably described as a universal function in the parameter ν⟨L⟩3 over the entire investigated range, and ηspNA⟨L⟩3(Mw[η])−1 ∝ (ν⟨L⟩3)3 was found over the region 102

The conformation and structure of methyl cellulose (MC) ether samples dissolved in pure water under dilute conditions were carefully reconsidered based on the results obtained using small-to-wide-angle neutron scattering (S-WANS), static light scattering (SLS), dynamic light scattering (DLS), and viscometric techniques. The examined MC samples possessed an average degree of substitution by methyl groups per glucose unit of ca 1.8 and weight average molar masses (

Toward a comprehensive understanding of the mechanism of glycerol as a moisturizer, studies on the hydrogen-bond (HB) structure of hydration water, which is known to be disordered by glycerol, are insufficient. To this aim, we evaluated the HB configurations based on the HOH bending and OH stretching spectra of the hydration water from those of glycerol/water mixtures by subtracting the contributions of bulk water and glycerol using dielectric relaxation spectroscopy. Analysis of the HOH bending band showed that hydration water-donating HBs lose the intermolecular bending coupling with increasing glycerol by replacing the water-water HBs with water-glycerol HBs. The OH stretching band provided more detailed insight into the HB configuration, indicating that the double-donor double-acceptor and double-donor single-acceptor configurations in bulk water change to a predominantly double-donor single-acceptor configuration in hydration water around glycerol. The formation of more donor HBs than acceptor HBs may be due to the steric constrains by glycerol and/or differences in the partial charge on the oxygen atom between water and glycerol.

Poly(2-methoxyethyl acrylate) (PMEA) is known to exhibit excellent thromboresistance, i.e., hardly causing blood-clot formation on its surface. Hence, PMEA and its analogues have been commercially used for blood-contacting materials in medical devices. In this study, we investigated the conformation and solvation state of PMEA in mixtures of tetrahydrofuran (THF) and water with various water volume fractions (ϕwater) by viscosity, sedimentation equilibrium, small-angle X-ray scattering (SAXS), and dielectric relaxation measurements. We also comparatively investigated those of poly[2-(2-methoxyethoxy)ethyl methacrylate] (PMe2MA) and polystyrene (PS). For all of these, THF is a good solvent and water is a nonsolvent or poor solvent. PMe2MA and PMEA show equally good thromboresistance, while PS does not at all. The solution properties of PMe2MA and PMEA were found to be quite different from PS. There are clear attractive interactions (or correlation) between the PMEA chain (or PMe2MA) and the waters in the vicinity of the chain despite their water insolubility. These correlated waters give additional scattering and the angular dependence of SAXS was analyzed in terms of the hydration layer model that has been used in protein solution scattering. The hydration is related to increasing both the chain stiffness and excluded volume. These distinctive properties are likely related to the origin of its good thromboresistance.

A cellulose nanocrystal (CNC) sample with an average particle length and width of 170 and 7.8 nm, respectively, that was prepared from chemical pulp via sulfuric acid hydrolysis procedures was used...

Background: Polypharmacy is associated with poor prognosis of patients with various diseases. However, it has not been precisely addressed how polypharmacy affects the clinical characteristics of the cardiovascular outpatients. The aim of this study is to search for the clinical characteristics related to the number of prescribed drugs in the cardiovascular outpatients. Also, we examine whether the number of the prescribed drugs affects the worsening of renal function. Methods: This retrospective study was conducted using the data of 259 continuous cardiovascular outpatients who were examined complete blood count (CBC) and serum creatinine. Results: In the univariate analysis, the number of prescribed drugs were associated with the number of cardiovascular diseases or their risk factors, age, white blood cells, platelet, body mass index, anemia, and chronic kidney disease stage 3b or higher. In the multivariable analysis, independent variables that significantly correlated with the number of prescribed drugs were the number of cardiovascular diseases or their risk factors, anemia, and chronic kidney disease stage 3b or higher. Among 259 patients, 208 patients received follow-up examination of serum creatinine. The number of prescribed drugs was the only factor that was associated with accelerated deterioration of renal function. Conclusions: Polypharmacy is associated not only with poor renal function but with accelerated deterioration of renal function. Polypharmacy may be causally related with renal dysfunction. Cardiol Res. 2020;11(1):15-21 doi: https://doi.org/10.14740/cr991

The solution properties of a water-soluble chemically modified cellulose ether, hydroxyethyl cellulose (HeC), were examined using static light scattering (SLS), dynamic light scattering (DLS), small-to-wide-angle neutron scattering (S-WANS), small-to-wide-angle X-ray scattering (S-WAXS) and viscometric techniques at 25 °C. The examined HeC samples had average molar substitution numbers ranging from 2.36 to 2.41 and weight average molar masses (Mw) that fell within a wide range from 87 to 1500 kg mol−1. Although the relationship between the determined radius of gyration (Rg) and Mw was described as Rg ∝ Mw~0.6, as is observed usually in flexible polymer solutions in good solvents, the observed scattering vector (q) dependencies of excess Rayleigh ratios were well interpreted using a rigid rod particle model, even in high-Mw samples. Moreover, the ratios of the formed particle length (L) evaluated assuming the model for rigid rods to the determined Rg showed the relationship LRg−1 ~ 3.5 irrespective of Mw and were close to those theoretically predicted for rigid rod particle systems, i.e., LRg−1 = 12. The observed SLS behavior suggested that HeC molecules behave just like rigid rods in aqueous solution. As the L values were not simply proportional to the average molecular contour length calculated from the Mw, the chain conformation or structure of the formed particles by HeC molecules in aqueous solution changed with increasing Mw. The q dependencies of excess scattering intensities observed using the S-WANS and S-WAXS experiments demonstrated that HeC molecules with Mw less than 200 kg mol−1 have a diameter of ~1.4 nm and possess an extended rigid rod-like local structure, the size of which increases gradually with increasing Mw. The observed Mw dependencies of the translational and rotational diffusion coefficients and the intrinsic viscosity of the particle suspensions strongly support the idea that the HeC molecules behave as rigid rod particles irrespective of their Mw.

The synthesis of 5-ethoxymethylfurfural (EMF) from glucose using metal chlorides or combined metal–surfactant catalysts as Lewis acids in a solution of ethanol/dimethyl sulfoxide was investigated. Metal chlorides such as aluminum chloride and chromium(III) chloride mainly produced 5-hydroxymethylfurfural and ethyl glucoside in reactions at 140 °C for 180 min. However, the combined metal–surfactant catalysts aluminum tridodecyl sulfate (Al(DS)3) and chromium(III) tridodecyl sulfate efficiently improved the yield of EMF from glucose. The maximum yield of EMF using Al(DS)3 was 37.9% at 160 °C for 60 min. Moreover, the EMF yields from other saccharides (fructose, mannose, sucrose, cellobiose, and inulin) in the presence of Al(DS)3 as a catalyst ranged from 31.2 to 59.3%.

The degree of polymerization and temperature dependencies of the molecular motions, configuration and hydration behaviour of glucose oligomers (Gn, n = 2 to 7, degree of polymerization) in aqueous solutions were investigated using extremely high-frequency dielectric spectrum measuring techniques up to 50 GHz. The obtained dielectric spectra for the aqueous Gn solutions were well decomposed into four Debye-type relaxation modes. The fastest relaxation mode j = 1 was assigned to the rotational process of free water molecules in the sample solution. The second fastest mode j = 2 was attributed to the exchange process of hydrated water molecules with free water molecules, and the third mode j = 3 was recognized as the rotational process of hydroxy groups attached to each repeating glucopyranoside (Glu) unit after their lifetimes of intramolecular hydrogen bonding. The slowest mode j = 4 at a relaxation time depending on n was assigned to the overall rotation of the Gn molecules possessing configurations similar to that of small fragments of single helical V-type crystalline structures at low temperatures. The presence of the dielectric mode j = 4 revealed that the Glu units possessed electric dipole moments carrying a component parallel to the Gn backbone aligned with the C1 → C4 direction. The number of hydrated water molecules per Glu unit (hydration number, nH) was determined for Gns in aqueous solutions in the temperature range from 10 °C to 70 °C via the relaxation strength of mode j = 1. The Gn oligomers were highly soluble in water within the temperature range examined, possessing nH values slightly dependent on n and demonstrated clear dehydration behaviour at approximately 30 °C with increasing temperature. These temperature dependencies of nH were substantially weaker than those of a model Glu unit compound, methyl α-D-glucopyranoside (G1). Then, the polymerization of glucose oligomers effectively depresses the dehydration behaviour of G1.

We examined the dielectric (DE) and nuclear magnetic resonance (NMR) spectroscopic behaviour of N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc), which are tertiary amide compounds that bear five-membered cyclic and open structures, respectively. They were examined to investigate the formation of anti-parallel dimers and tetramers in a dipole configuration in the pure liquid state and in benzene solution over a wide concentration range at 25 °C. Because the Kirkwood correlation factors of electric dipoles considerably decreased with increasing concentrations in both the NMP and DMAc systems and because the second DE relaxation modes were clearly observed to exhibit relaxation times that are longer than those of the first modes assigned to the rotational relaxation of monomeric molecules, anti-parallel dimers are formed due to dipole-dipole interactions with increasing concentrations. Assuming a chemical process between the monomers (MONs) and the anti-parallel dimer (DIM), 2MON ⇄ DIM, the equilibrium constants for the anti-parallel dimer formation were determined to be KDEd ∼ 1.2 M-1 for NMP and 0.35 M-1 for DMAc, based on the first DE relaxation strength. The fact that the evaluated KDEd values substantially increased with increasing concentrations in the range above ca. 1.0 M strongly suggested the formation of higher order intermolecular associations instead of dimers. Chemical shifts in the 1H-NMR spectra assigned to (N)CH3 and (5)CH2 protons of NMP and the two (Nα)CH3 and (Nβ)CH3 protons of DMAc dissolved in (d)Bz substantially changed with increasing concentrations due to the formation of intermolecular associations. The states occupied by MONs, DIMs and tetramers (TETs) were evaluated from chemical shift data as a function of the concentrations in the NMP and DMAc systems. Then, the equilibrium constants for the dimer and tetramer formation (2DIM ⇄ TET) were determined to be KNMRd ∼ 1.2 M-1 and KNMRt ∼ 0.2 M-1 for NMP and KNMRd ∼ 0.35 M-1 and KNMRt ∼ 0.25 M-1 for DMAc. The reason for the differences in the equilibrium constants between NMP and DMAc may be related to the difference in motional freedom between the cyclic and open structures. The formation of anti-parallel DIMs and TETs was also confirmed by semi-empirical quantum chemical calculations for both NMP and DMAc molecules.

The structure and conformation of methyl cellulose (MC) and hydroxypropyl methyl cellulose (HpMC) ether samples dissolved in dilute aqueous (D2O) solutions at a temperature of 25 °C were reconsidered in detail based on the experimental results obtained using small- and wide-angle neutron scattering (S-WANS) techniques in a range of scattering vectors (q) from 0.05 to 100 nm−1. MC samples exhibited an average degree of substitution (DS) by methyl groups per glucose unit of DS = 1.8 and the weight average molar mass of Mw = 37 × 103 and 79 × 103 g mol−1. On the other hand, HpMC samples possessed the average molar substitution number (MS) by hydroxypropyl groups per glucose unit of MS = 0.25, DS = 1.9, and Mw = 50 × 103 and 71 × 103 g mol−1. The concentration-reduced scattering intensity data gathered into a curve for the solutions of identical sample species clearly demonstrated the relationship I(q)c−1 ∝ q−1 in a q range from 0.05 to 2.0 nm−1, and small interference peaks were found at q ∼ 7 and 17 nm−1 for all examined sample solutions. These observations strongly revealed that form factors for both the MC and HpMC samples were perfectly described with that for long, rigid rod particles with average diameters of 0.8 and 0.9 nm, respectively, and with an inner structure with characteristic mean spacing distances of ca. 0.9 and 0.37 nm, respectively, regardless of the chemically modified conditions and molar masses. A rationally speculated structure model for the MC and HpMC samples dissolved in aqueous solution was proposed.

A cellulose nanocrystal (CNC) sample prepared from chemical pulp via sulfuric acid hydrolysis procedures has been supplied by InnoTech Alberta Inc. in the shape of white dry powder as a prototype product. Some transport coefficients were precisely investigated for the CNC sample in aqueous suspensions at the room temperature of 25 °C such as the average rotational and translational diffusion coefficients (Dr and Dt) and viscoelastic relaxation times (τv) at dilute conditions. The determined values, Dr ≈ 2.3 × 103 s–1 and Dt ≈ 1.0 × 10–11 m2 s–1, using depolarized and usual dynamic light scattering (DLS) techniques, respectively, proposed the consistent length and width of L ≈ 170 nm and W ≈ 7.6 nm via a theoretical model for monodisperse rigid rods dispersed in pure water. The viscoelastic behavior for aqueous CNC suspensions containing spherical probe particles was examined using DLS rheological techniques. The obtained value of τv = 1.0 × 10–4 s fairly agrees with that of (6Dr)−1 ≈ 7.4 × 10–5 s. Because the theoretical model for monodisperse rods denotes the relationship τv = (6Dr)−1, this observation strongly confirms that the CNC sample behaves as approximately monodisperse rigid rodlike particles. Transmission electron microscopy (TEM) images clearly demonstrated a bimodal distribution in rod length with major and small minor peaks at ca. 150 and 240 nm, respectively. Then, the reason for the observed disagreement between the L values resulted from the transport coefficients and the major peak in TEM images is the presence of the small minor component with L ≈ 240 nm. Consequently, individual nanosize rodlike crystalline particles in the CNC sample well disperse without forming large aggregations because of strong interactions and behave as isolated individual rods in dilute aqueous suspensions.

The hydration numbers of cellulose ethers dissolved into aqueous solution were determined using extremely high-frequency dielectric spectroscopic methods, up to 50 GHz, in which the frequency range of the major dielectric dispersion of free water molecules is clearly observable. Methyl cellulose, hydroxypropylmethyl cellulose, and hydroxyethylmethyl cellulose samples at relatively high degrees of substitution by methyl groups ranged from 1.4 to 1.9, which are an essential reason for water solubility, and additional low molar substitution by hydroxypropyl or hydroxyethyl groups from 0 to 0.25 bearing molar masses (Mw) ranging from 20 × 103 to 300 × 103 was examined in this study. All the samples dissolve well into cold water below room temperature, ca. 25 °C; however, their aqueous solutions show distinct cloud points at high temperatures, such as 38–53 °C, depending not so much on the Mw values but on the substitution condition substantially. The determined hydration numbers per glucopyranose unit (nH) fo...

Pravastatin is an inhibitor of 3-hydroxy-3-methyl- glutaryl-coenzyme A reductase that has been reported to have therapeutic applications in a range of inflammatory conditions. The aim of the present study was to assess the radioprotective effects of pravastatin in an experimental animal model. Mice were divided into two groups: The control group received ionizing radiation with no prior medication, while the pravastatin group received pravastatin prior to ionizing radiation. Pravastatin was administered orally at 30 mg/kg body weight in drinking water at 24 and 4 h before irradiation. Intestinal crypt epithelial cell survival and the incidence of apoptosis in the intestine and lung were measured post-irradiation. The effect of pravastatin on intestinal DNA damage was determined by immunohistochemistry. Finally, the effect of pravastatin on tumor response to radiotherapy was examined in a mouse mesothelioma xenograft model. Pravastatin increased the number of viable intestinal crypts and this effect was statistically significant in the ileum (P

The formation of anti-parallel dimers ((EC)2) of ethylene carbonate (EC) in solution is discussed via dielectric data determined over a frequency range up to 3 THz. Two major dielectric processes have been identified in both benzene (Bz) and dimethyl carbonate (DMC) solutions. The relaxation times were ca. 8 and ca. 20 ps in Bz, and ca. 20 and ca. 40 ps in DMC solution for the two relaxation processes, respectively. The population of monomeric EC was evaluated from the strength of the faster relaxation mode assigned to the rotational mode of monomeric EC. Equilibrium constants (Kd) for the (EC)2 formation in the two solvents were determined as functions of the concentration at room temperature assuming a process, 2EC \( \rightleftharpoons \) (EC)2. The libration of EC molecules was observed as a sharper resonance signal at ca. 1.5 × 1013 s−1 when they existed as monomeric EC rather than in the form of (EC)2 in Bz, whereas the signal was not so sharp in DMC. The fact that the determined Kd values depended ...

Poly(2-ureidoethylmethacrylate) (PUEMn) was synthesized via reversible addition-fragmentation chain transfer (RAFT) radical polymerization and following polymer reaction. We prepared two PUEMn samples with different degrees of polymerization (n = 100 and 49). The polymers exhibited upper critical solution temperature (UCST) in phosphate-buffered saline (PBS) solution. The phase separation temperature (Tp) in PBS can be controlled ranging from 17 to 55 °C by changing molecular weight of the polymer, polymer concentration, and adding NaCl concentration. The polymers in PBS formed coacervate drops by liquid–liquid phase separations below Tp. Results of the dielectric relaxation measurement, the hydration number per monomeric unit was 5 above Tp. Based on a fluorescence study, the polymer formed slightly hydrophobic environments below Tp. The liquid–liquid phase separation was occurred presumably because of weak hydrophobic interactions and intermolecularly hydrogen bonding interactions between the pendant ureido groups. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2845–2854

The equilibrium constants for the antiparallel dimer formation of ethylene carbonate (EC) in solutions of pure solvents, such as benzene (Bz) and dimethyl carbonate (DMC), were quantitatively deter...

Partially chemically modified poly(vinyl alcohol) synthesized via random introduction of a diol-type monomer (mPVA) shows much higher solubility in water than normal homo poly(vinyl alcohol) (PVA). To clarify the reason for the high solubility of mPVA, we investigated the temperature dependencies of the hydration numbers per hydroxy group (mOH) for mPVA at various diol-type monomer contents from x = 0 (PVA) to 0.12 using extremely high frequency dielectric relaxation measurements up to 50 GHz over a temperature range from 10 to 70 °C. The values of mOH for mPVA in the temperature range below 20 °C looked constant and increased from 2.4 to 3.4 with increasing x. Above 20 °C, the values of mOH decreased with increasing temperature and approached a constant value close to unity above 70 °C irrespective of x. Although the random introduction of the diol-type monomer into the mPVA backbones effectively increased the mOH values, broad dehydration was commonly observed at approximately 40 °C irrespective of the ...

Polaprezinc (PZ), an antiulcer drug, has been reported to have antioxidant properties. The aim of the present study was to assess the feasibility and efficacy of administering PZ for radiation-induced mucositis in head and neck cancer patients. Patients with newly diagnosed head and neck cancer were enrolled in this prospective study. PZ was prepared as an oral rinse. The PZ oral rinse was used four times per day during the course of radiotherapy. Sequential changes in radiation mucositis were assessed during and after radiotherapy according to the Common Terminology Criteria for Adverse Events, version 3.0. Furthermore, a retrospective comparison analysis was performed to assess the efficacy of PZ for radiation-induced mucositis. A total of 32 patients were enrolled in the prospective study of the PZ oral rinse. Radiotherapy was performed up to a total dose of 60-66 Gy using a conventional schedule combined with chemotherapy. Of the 32 patients, 30 (93.8%) reported no complaints due to the PZ oral rinse. In addition, PZ was not associated with severe adverse effects. Among the patients who received PZ, grade 3 mucositis was observed in 29.0% based on the mucosal findings and in 39.3% based on the symptoms. In the patients who did not receive PZ, the incidence of grade 3 mucositis was 40.0% based on the mucosal findings and 60.7% based on the symptoms. Moreover, PZ promoted the recovery from mucositis caused by chemoradiotherapy and was not associated with reduced tumor response to radiotherapy. Therefore, the PZ oral rinse was well tolerated and proved to be efficient for the treatment of radiotherapy-induced oral mucositis.

Background:Proton pump inhibitors (PPI) are frequently prescribed in combination with aspirin for preventing peptic ulcer in patients with atherosclerotic diseases. In contrast, long-term use of PPI has been suggested to be associated with iron or vitamin B12deficiency. The effect of PPI on hemoglobin (Hb) concentration, however, has not been clarified in cardiovascular outpatients.Methods and Results:We retrospectively investigated the clinical characteristics of 278 continuous outpatients who received blood test including complete blood count and serum creatinine concentration (mean age, 69.9±10.8 years; male, 68.7%). The frequency of anemia was 51% in patients receiving PPI and 19% in those not receiving PPI (chi-squared test, P

Dynamics of 4-pentyl-4’-cyanobiphenyl (5CB) dissolved in several polymers at concentrations of 3 - 7 wt% was examined by dielectric relaxation measurement. Glassy (segmental) mode of the matrix polymer was also investigated by viscoelastic measurements for the same samples. Polystyrene (PS), poly(4-methylstyrene) (P4MS), and poly(4-tert-butylstyrene) (PtBS) were used as host polymers considering that they have the same backbone structure but different side-chain bulkiness. Two dielectric relaxation modes (slow and fast modes) of 5CB component appeared in all the mixtures and the relative intensity of the fast mode increased in the order of PS < P4MS < PtBS, corresponding to the order of the side-chain bulkiness and main chain stiffness. The effects of such chemical structure differences on the two relaxation modes, particularly their temperature dependence were examined in detail. Comparison of relaxation times for the fast mode and the segmental dynamics of the matrix polymer suggests that the fast mode was attributed to the restricted orientational fluctuation, which includes precession motion around the long axis, of 5CB molecule in a confined space formed by slow polymer chains. The dielectric intensity of the fast mode increased with increasing side-chain bulkiness of polymers. This means that the larger side-chain decreases the spatial restriction for the movement of guest 5CB molecules in the glassy state. The slow mode was attributed to the rotational motion of 5CB molecule nearly cooperative with the segmental motion of matrix polymer. The relaxation times of dielectric slow mode and viscoelastic glass mode were compared. Temperature dependence of the slow mode was slightly different from that of the segmental motion of polymer corresponding to the glass mode. From the difference between these relaxation times, the correlation length relevant to the glass mode was determined as functions of temperature for the three polymers.

It has been well-known that aqueous solutions of poly(ethylene oxide) (or poly(ethylene glycol)) (PEO) are clear in a low temperature range but show clouding points due to phase separation behavior at rather high temperatures close to 100 °C slightly dependent on its average molar mass and concentration. We carried out extremely high frequency dielectric relaxation measurements up to 50 GHz over a temperature range from 10 to 70 °C to determine the temperature dependence of a hydration number per ethylene oxide monomer unit (mEO) in PEOs with the average molar masses higher than 3000. The obtained mEO was a constant value of ca. 4 in a temperature range lower than 30 °C and decreased rather gradually and approached ca. 2 at 70 °C. The temperature dependence of mEO, hydration/dehydration behavior, confirmed in this study should be the essential reason for the phase separation behavior observed at high temperatures. The hydration/dehydration behavior observed in this study was compared with that reported pr...

Poly(N-methylglycine) (NMGn) and poly(N-ethylglycine) (NEGn) obtained by polymerization reactions initiated by benzylamine have no carboxy termini, such as those in normal polyamides, but have only amino termini, which exist primarily as cations in aqueous media at a pH value of ca. 9.5, observed in aqueous solutions without any buffer reagents. Therefore, polypeptoids, such as NMGn and NEGn, possessing a degree of polymerization (DP) higher than a certain value behave as cationic monopolar polymeric chain molecules in aqueous solution. It has not been clarified so far whether such a monopolar chain molecule exhibits dielectric relaxation (DR) behavior resulting from its molecular motions in aqueous media as dipolar chain molecules. DR measurements revealed that NMG19 and NEG17, possessing DPs of 19 and 17, respectively, dissolved in pure water clearly demonstrated pronounced DR behavior caused by fluctuating molecular motions of cationic termini at relaxation times of ca. 4 and 9 ns at 10 °C (283 K). The hydration numbers of NMG19 and NEG17 per monomeric residue (nm) in aqueous solution were also evaluated via DR data as functions of temperature, and the nm value of ca. 4.5 at 10 °C showed a remarkable reduction to ca. 2.0 around 40 °C (313 K) and 30 °C (303 K), depending on differences in the substituted group: methyl and ethyl groups. This temperature-dependent hydration/dehydration behavior found in NMG19 and NEG17 slightly influenced the sizes and molecular dynamics of the monopolar chain molecules in aqueous solution.

The purpose of the present study was to establish an experimental rat model for late radiation proctitis, and to examine the assessment strategy for late radiation proctitis. A total of 57 Wistar rats were used. Fourty-five of the rats were exposed to selective rectal irradiation with a single fraction of 25 Gy. These rats were sacrificed at the 4(th), 12(th), 24(th), and 37(th) week following irradiation. The remaining 12 rats comprised the control group without irradiation. The rectal mucosa of each rat was evaluated macroscopically and pathologically. The number of vessels in the rectal mucosa was counted microscopically. In addition, the vascular stenosis was evaluated. In the results, the degree of clinical and macroscopic findings decreased following acute proctitis and developed later. In the pathological examination, mucosal changes and microangiopathy were followed up, as well. The absolute number of vessels in the rectum was the greatest at the 12(th) week following irradiation and was the lowest in the control group. The severity of the microangiopathy was also well evaluated. To conclude, we established an animal experimental model of late radiation proctitis, and also established an assessment strategy to evaluate objectively the severity of late radiation proctitis with focusing on microangiopathy using an animal experimental model. This model can be used as an animal experimental model of radiation-induced microangiopathy.

We conducted dielectric and viscoelastic relaxation measurements for polystyrene (PS)/4-pentyl-4′-cyanobiphenyl (5CB) and PS/4-pentyl-4′′-cyanoterphenyl (5CT) mixtures in the miscible state with the weight fractions of 5CB or 5CT from 0.04 to 0.27 to examine the relationship between two-component dynamics in the mixture. Dielectric relaxation measurements mainly probed the dynamics of low-mass molecule (LM), 5CB or 5CT, because of the much larger dipole moment of LMs compared to that of PS. PS/5CB mixtures exhibited bimodal dielectric relaxation, while PS/5CT showed unimodal relaxation. The observed two relaxation modes (slow and fast modes) in PS/5CB were attributed to the full rotational motion and partial rotational motion of 5CB, respectively. The latter motion is allowed in the restricted space surrounded by less mobile PS matrix. In the case of 5CT, the fast mode was suppressed due to the larger size of 5CT molecule, and only the slow mode (rotational mode) appeared. The relaxation times of slow mod...

Purpose The purpose of the present study was to standardize the experimental rat model of radiation proctitis and to examine the efficacy of polaprezinc on radiation proctitis. Methods and Materials A total of 54 female Wistar rats (5 weeks old) were used. The rats were divided into three groups: those treated with polaprezinc (PZ+), those treated with base alone, exclusive of polaprezinc (PZ−), and those treated without any medication (control). All the rats were irradiated to the rectum. Polaprezinc was prepared as an ointment. The ointment was administered rectally each day after irradiation. All rats were killed on the 10th day after irradiation. The mucosal changes were evaluated endoscopically and pathologically. The results were graded from 0 to 4 and compared according to milder or more severe status, as applicable. Results According to the endoscopic findings, the proportion of mild changes in the PZ+, PZ−, and control group was 71.4%, 25.0%, and 14.3% respectively. On pathologic examination, the proportion of low-grade findings in the PZ+, PZ−, and control group was 80.0%, 58.3%, and 42.9% for mucosal damage, 85.0%, 41.7%, and 42.9% for a mild degree of inflammation, and 50.0%, 33.3%, and 4.8% for a shallow depth of inflammation, respectively. The PZ+ group tended to have milder mucosal damage than the other groups, according to all criteria used. In addition, significant differences were observed between the PZ+ and control groups regarding the endoscopic findings, degree of inflammation, and depth of inflammation. Conclusions This model was confirmed to be a useful experimental rat model for radiation proctitis. The results of the present study have demonstrated the efficacy of polaprezinc against acute radiation-induced rectal disorders using the rat model.

We conducted dynamic viscoelastic and birefringence measurements for dynamically homogeneous mixtures, polystyrene (PS)/4-pentyl-4′-cyanobiphenyl (5CB), to examine the orientational coupling between PS segments and 5CB molecules. It was also investigated whether dynamic homogeneity was correlated with orientational coupling. We determined stress-optical coefficients CR of the PS/5CB mixtures in the rubbery region. With increasing the 5CB concentration, CR increased indicating the cooperative orientation of the 5CB molecule along with the PS segment to some extent. We proposed a new method to quantitatively evaluate the orientational coupling, referred to as a nematic interaction (NI), between polymer segments and low-mass molecules in the mixtures from the concentration dependence of CR. Using the proposed method we determined the NI parameter between PS and 5CB, ePS,5CB. The determined ePS,5CB value was smaller than (about 1/4 of) that between PS segments (ePS,PS) suggesting the weaker NI acting between ...

Relationship between segmental relaxation and normal-mode relaxation has been studied for molten poly(butylene oxide)s having various molecular weights by broadband dielectric spectroscopy over a wide temperature (T) range. We found that T dependence of the segmental relaxation time, τs, was weaker than the normal mode time, τn, at high T(>250 K ∼ Tg + 50 K), and the τn/τs ratio systematically decreased with increasing temperature. This high temperature complexity, whose mechanism has not been discussed in detail so far, was quantitatively explained by assuming the two step processes: local conformation change of polymers (elementary process) occurs first, and then the motion of a segment unit (second process) occurs. It was also found that the elementary process was strongly correlated with the experimentally observed β-relaxation.

The dynamic behaviors of ionic liquid samples consisting of a series of 1-alkyl-3-methylimidazolium cations and various counteranionic species are investigated systematically over a wide frequency range from 1 MHz to 20 GHz at room temperature using dielectric relaxation (DR) and nuclear magnetic resonance (NMR) spectroscopies. DR spectra for the ionic liquids are reasonably deconvoluted into two or three relaxation modes. The slowest relaxation times are strongly dependent upon sample viscosity and cation size, whereas the relaxation times of other modes are almost independent of these factors. We attribute the two slower relaxation modes to the rotational relaxation modes of the dipolar cations because the correlation times of the cations evaluated using longitudinal relaxation time (T(1) (13)C NMR) measurements corresponded to the dielectric relaxation times. On the other hand, the fastest relaxation mode is presumably related to the inter-ion motions of ion-pairs formed between cationic and anionic species. In the case of the ionic liquid bis(trifluoromethanesulfonyl)imide, the system shows marked dielectric relaxation behavior due to rotational motion of dipolar anionic species in addition to the relaxation modes attributed to the dipolar cations.