Using neutron methods SANS and PGAA to study evolution of structure and composition of alkali-doped polybenzimidazole membranes

Babcock, E.,Szekely, N.,Konovalova, A.,Lin, Y.,Appavou, M.-S.,Mangiapia, G.,Revay, Z.,Stieghorst, C.,Holderer, O.,Henkensmeier, D.,Lehnert, W.,Carmo, M. Elsevier 2019 Journal of membrane science Vol.577 No.-

<P><B>Abstract</B></P> <P>Potassium hydroxide (KOH) doped polybenzimidazole (PBI) membranes are investigated as compelling candidates for water electrolysis applications, drastically reducing the ohmic losses in contrast to thick ZrO<SUB>2</SUB> based diaphragms. Using small angle neutron scattering (SANS) we have found that the structure of the (KOH doped) PBI changes with doping time on a minute time scale, and that the development of the structure is highly dependent on the KOH concentration. This data is correlated with macroscopic measurements of membrane swelling resulting from the doping process which also occurs on a minute time scale. Then, using prompt gamma activation analysis (PGAA) to follow the changes in time of the chemical composition, we have found that the K concentration of these samples only increases slightly with doping times after a very rapid initial uptake, reaching a saturation value that is relatively independent of KOH concentration for long doping times of up to 24 h. However measurements of similarly doped samples show increases in ion-conductivity of nearly 3 fold, and resistivity reductions of over 2 fold on the same time scales. These measurements prove that PGAA is a sensitive method to follow changes in the chemical compositions during doping, while SANS can give information on the sub-micro structural changes of polymer electrolyte membranes. Since these methods can be correlated with <I>ex-situ</I> measurements of composition, resistance, ion-conductivity and macro-structure, the combined use of PGAA and SANS provides a promising means for <I>in-operando</I> study in order to elucidate changes in membrane performance due to electrochemical cycling, as well as to help characterize and optimize doping parameters though in-situ doping measurements, by enabling real-time study of such membrane systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Elucidating the doping of Alkali-doped Polybenzimidazole membranes. </LI> <LI> Complementary structure and composition information from SANS and PGAA to study functional membranes. </LI> <LI> Structure varies over doping time for KOH doped Polybenzimidazole membranes. </LI> <LI> New possibilities for in-situ and in-operando characterization. </LI> </UL> </P>

The Mechanism of the Decomposition of a Bronchodilator, S-Nitroso-N-acetyl-D,L-penicillamine (SNAP), by a Bronchoconstrictor, Aqueous Sulfite: Detection of the N-Nitrosohydroxylamine-N-sulfonate ion

Holder, Alvin A.,Marshall, Sophia C.,Wang, Peng George,Kwak, Chee-Hun Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.3

The mechanism of the decomposition of a bronchodilator, S-nitroso-N-acetyl-D,L-penicillamine (SNAP) by a bronchoconstrictor, aqueous sulfite, has been investigated in detail. The decomposition was studied using a conventional spectrophotometer at 336 nm over the ranges: 0.010 ≤ $[S^{IV}]_T$ ≤ 0.045 mol $dm^{-3}$, 3.96 ≤ pH ≤ 6.80 and 15.0 ≤ θ≤ 30.0 ℃, 0.60 ≤ I ≤ 1.00 mol $dm^{-3}$, and at ionic strength 1.00 mol $dm^{-3}$ (NaCl). The rate of reaction is dependent on the total sulfite concentration and pH in a complex manner, i.e., $k_{obs}\;=\;k_1K_2[S^{IV}]_T/ ([H^+]\;+\;K_2)$. At 25.0 ℃, the second order rate constant, $k_1$, was determined as $12.5\;{\pm}\;0.15\;mol^{-1}\;dm^3\;s^{-1}$. ${\Delta}H^{neq}\;=\;+32\;{\pm}\;3 kJ\;mol^{-1}\;and\;{\Delta}S^{\neq}\;=\;-138\;{\pm}\;13\;J\;mol^{-1}K^{-1}$. The N-nitrosohydroxylamine-N-sulfonate ion was detected as an intermediate before the formation of any of the by-products, namely, N-acetyl-D,L-penicillamine. The effect of concentration of aqueous copper(Ⅱ) ions on this reaction was also examined at pH 4.75, but there was no dependence on $[Cu^{2+}]$. In addition, the $pK_a$ of SNAP was determined as 3.51 ± 0.06 at 25.4 ℃ [I = 1.0 mol $dm^{-3}$ (NaCl)].

The Mechanism of the Decomposition of a Bronchodilator, S-Nitroso-N-acetyl-D,Lpenicillamine(SNAP), by a Bronchoconstrictor, Aqueous Sulfite: Detection of theN-Nitrosohydroxylamine-N-sulfonate ion

AlvinA.Holder,Sophia C. Marshall,Peng George Wang,Chee-Hun Kwak 대한화학회 2003 Bulletin of the Korean Chemical Society Vol.24 No.3

Postoperative nausea and vomiting in patients undergoing colorectal surgery within an institutional enhanced recovery after surgery protocol: comparison of two prophylactic antiemetic regimens

Jennifer Holder-Murray,Stephen A Esper,Michael L Boisen,Julie Gealey,Katie Meister,David S Medich,Kathirvel Subramaniam 대한마취통증의학회 2019 Korean Journal of Anesthesiology Vol.72 No.4

Background: Enhanced recovery protocols (ERP) provide optimal perioperative care for surgical patients. Postoperative nausea and vomiting (PONV) is common after colorectal surgery (CRS). We aim to compare the efficacy of aprepitant to a cost-effective alternative, perphenazine, as components of triple antiemetic prophylaxis in ERP patients. Methods: Patients who underwent ERP CRS at a single institution from July 2015 to July 2017 were evaluated retrospectively. Only subjects who received aprepitant (Group 1) or perphenazine (Group 2) preoperatively for PONV prophylaxis were included. Patient characteristics, simplified Apfel PONV scores, perioperative medications, and PONV incidence were compared between the groups. PONV was defined as the need for rescue antiemetics on postoperative days (POD) 0–5. Results: Five hundred ninety-seven patients underwent CRS of which 498 met the inclusion criteria. Two hundred thirty- one (46.4%) received aprepitant and 267 (53.6%) received perphenazine. The incidence of early PONV (POD 0–1) was comparable between the two groups: 44.2% in Group 1 and 44.6% in Group 2 (P = 0.926). Late PONV (POD 2–5) occurred less often in Group 1 than Group 2, respectively (35.9% vs. 45.7%, P = 0.027). After matching the groups for preoperative, procedural, and anesthesia characteristics (164 pairs), no difference in early or late PONV could be demonstrated between the groups. Conclusions: The incidence of PONV remains high despite most patients receiving three prophylactic antiemetic medications. Perphenazine can be considered a cost-effective alternative to oral aprepitant for prophylaxis of PONV in patients undergoing CRS within an ERP.

Possible clinical implications of prostate capsule thickness and glandular epithelial cell density in benign prostate hyperplasia

Katherine G. Holder,Bernardo Galvan,Andrew S. Knight,Freedom Ha,Reagan Collins,Preston E. Weaver,Luis Brandi,Werner T. de Riese 대한비뇨의학회 2021 Investigative and Clinical Urology Vol.62 No.4

Purpose: The negative correlation between BPH-size and incidence of prostate cancer (PCa) is well-documented in the literature, however the exact mechanism is not well-understood. The present study uses histo-anatomical imaging to study prostate volume in correlation to prostate capsule thickness, and glandular epithelial cell density within the peripheral zone (PZ). Materials and Methods: Specimens were selected from radical prostatectomies ranging from 20 to 160 mL based on ease of anatomical reconstruction by the slides. A total of 60 patients were selected and underwent quantitative measurements of prostate capsule thickness and glandular epithelial density within the PZ using computer-based imaging software. Pearson's correlation and a stepwise multiple linear regression analysis was conducted to determine the relationship between these measured parameters and the clinical characteristic of these patients. Results: Pearson's correlation analysis revealed a strongly significant, negative correlation between prostate volume and glandular epithelial cell density (r(58)=−0.554, p<0.001), and a strongly significant, positive correlation between prostate volume and average capsule thickness (r(58)=0.462, p<0.001). Results of multiple regression analysis showed that average glandular epithelial cell density added statistically to this prediction (p<0.05). Conclusions: The results suggest that growth of the transition zone in BPH causes increased fibrosis of the PZ, leading to atrophy and fibrosis of glandular cells. As 80% of PCa originates from the glandular epithelium within the PZ, this observed phenomenon may explain the inverse correlation between BPH and PCa that is well-documented in the literature.

Raising the superconducting transition temperature in cuprates within a two-component scenario

Annette Bussmann-Holder 한국물리학회 2004 Current Applied Physics Vol.4 No.5

Two-component or two-channel superconductivity has been proposed since long to be a source of raising the superconducting transition temperatureTc considerably. The rst observation of two-component superconductivity was made in Nb-doped SrTiO3,yet without the hope forTc enhancement. An unambiguous observation of two superconducting gaps has been made in the recentlydiscovered high-Tc compound MgB 2 where the two component interband interaction ampliesTc by a factor of 1.6 as compared to asingle band system. Another candidate for such a scenario has been speculated to be veried in the cuprate superconductors, but theoverwhelming experimental evidence for a d-wave order parameter in the CuO2 planes has largely suppressed this aspect. Here it isshown that the coexistence of an s-wave and d-wave order parameter in cuprates is a scenario in which the observed highTcs can berealized. The crucial quantity is here the pairwise exchange interaction of holes between the two channels caused by quantuminterference. Lattice eects on superconductivity are explicitly incorporated and shown to be of major relevance to superconduc-tivity including various exotic isotope effects.

Implementation of a perioperative ketamine shortage mitigation strategy

Dibridge Julie,Holder-Murray Jennifer,Skledar Susan,Subramaniam Kathirvel,Esper Stephen A 대한마취통증의학회 2020 Korean Journal of Anesthesiology Vol.73 No.3

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The Pricing of CBOT Exchange Seat

Taewoo You,Mark Holder 한국재무학회 2007 한국재무학회 학술대회 Vol.2007 No.04

This paper analyzes the behavior of the CBOT seat prices for the post-1975 period. Based on the time-series property of seat returns and the empirical link between seat returns and economic factors, we develop a conditional multi-factor model, where the price of risks are assumed to be linearly generated from the ARIMA estimates of the factor values. Particularly, we find the close short-run and long-run link between the CBOT seat price and CBOT trading volume. Importantly, the CBOT seat returns appear to exhibit significant power in predicting stock market returns, the growth of CBOT trading volume, the growth of industrial production, and interest rate. Based on the dynamic pricing model including three factors by Fama and French, we find that excess seat returns are time-varying with some expected factor variables, such as expected size premium ( SMBe ), expected CBOT trading volume (VOLe ), and expected interest rate ( INTe ). Seat returns are particularly sensitive to the size premium shock ( SMBu ). We conclude that the pricing mechanism of CBOT seats is similar to that of a well-diversified stock market portfolio.

Analysis of resting noise characteristics of three EIT systems in order to compare suitability for time difference imaging with scalp electrodes during epileptic seizures

Fabrizi, L,McEwan, A,Woo, E,Holder, D S IOP Pub 2007 PHYSIOLOGICAL MEASUREMENT Vol.28 No.7

<P>Electrical impedance tomography measurements in clinical applications are limited by an undesired noise component. We have investigated the noise in three systems suitable for imaging epileptic seizures, the UCH Mark1b, UCH Mark2.5 and KHU Mark1 16 channel, at applied frequencies in three steps from 1 to 100 kHz, by varying load impedance, single terminal or multiplexed measurements, and in test objects of increasing complexity from a resistor to a saline filled tank and human volunteer. The noise was white, and increased from about 0.03% rms on the resistor to 0.08% on the human; it increased with load but was independent of use of the multiplexer. The KHU Mark1 delivered the best performance with noise spectra of about 0.02%, which could be further reduced by averaging to a level where reliable imaging of changes of about 0.1% estimated during epileptic seizures appears plausible.</P>

Elastic Anomalies Associated with the Antiferroelectric Phase Transitions of PbHfO3 Single Crystals

고재현,Krystian Roleder,Andrzej Majchrowski,Annette Bussmann-Holder 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.8

The temperature dependence of the elastic properties of antiferroelectric PbHfO3 was investigatedby using Brillouin scattering. The two structural phase transitions of antiferroelectricantiferroelectric-paraelectric phases were clearly identified from the discontinuous changes in theacoustic mode frequencies and the hypersonic damping. The substantial softening of the modefrequency, along with the remarkable increase in the acoustic damping observed in the paraelectricphase, indicated the formation of precursor noncentrosymmetric (polar) clusters and their couplingto the acoustic waves. This was corroborated by the observation of quasi-elastic central peaks,the intensity of which grew upon cooling toward the Curie point. The obtained relaxation timeexhibited a slowing-down behavior, suggesting that the dynamics of the precursor clusters becamemore sluggish on approaching the phase transition temperature.