Tailored donor-acceptor polymers with an A-D1-A-D2 structure: controlling intermolecular interactions to enable enhanced polymer photovoltaic devices.

PubMed

Qin, Tianshi; Zajaczkowski, Wojciech; Pisula, Wojciech; Baumgarten, Martin; Chen, Ming; Gao, Mei; Wilson, Gerry; Easton, Christopher D; Müllen, Klaus; Watkins, Scott E

2014-04-23

Extensive efforts have been made to develop novel conjugated polymers that give improved performance in organic photovoltaic devices. The use of polymers based on alternating electron-donating and electron-accepting units not only allows the frontier molecular orbitals to be tuned to maximize the open-circuit voltage of the devices but also controls the optical band gap to increase the number of photons absorbed and thus modifies the other critical device parameter-the short circuit current. In fact, varying the nonchromophoric components of a polymer is often secondary to the efforts to adjust the intermolecular aggregates and improve the charge-carrier mobility. Here, we introduce an approach to polymer synthesis that facilitates simultaneous control over both the structural and electronic properties of the polymers. Through the use of a tailored multicomponent acceptor-donor-acceptor (A-D-A) intermediate, polymers with the unique structure A-D1-A-D2 can be prepared. This approach enables variations in the donor fragment substituents such that control over both the polymer regiochemistry and solubility is possible. This control results in improved intermolecular π-stacking interactions and therefore enhanced charge-carrier mobility. Solar cells using the A-D1-A-D2 structural polymer show short-circuit current densities that are twice that of the simple, random analogue while still maintaining an identical open-circuit voltage. The key finding of this work is that polymers with an A-D1-A-D2 structure offer significant performance benefits over both regioregular and random A-D polymers. The chemical synthesis approach that enables the preparation of A-D1-A-D2 polymers therefore represents a promising new route to materials for high-efficiency organic photovoltaic devices.

A study of the red-shift of a neutral donor bound exciton in GaN nanorods by hydrogenation

NASA Astrophysics Data System (ADS)

Park, Byung-Guon; Lee, Sang-Tae; Reddeppa, Maddaka; Kim, Moon-Deock; Oh, Jae-Eung; Lee, Sang-Kwon

2017-09-01

In this paper we account for the physics behind the exciton peak shift in GaN nanorods (NRs) due to hydrogenation. GaN NRs were selectively grown on a patterned Ti/Si(111) substrate using plasma-assisted molecular beam epitaxy, and the effect of hydrogenation on their optical properties was investigated in detail using low-temperature photoluminescence measurements. Due to hydrogenation, the emissions corresponding to the donor-acceptor pair and yellow luminescence in GaN NRs were strongly suppressed, while the emission corresponding to the neutral to donor bound exciton (D0X) exhibited red-shift. Thermal annealing of hydrogenated GaN NRs demonstrated the recovery of the D0X and deep level emission. To determine the nature of the D0X peak shift due to hydrogenation, comparative studies were carried out on various diameters of GaN NRs, which can be controlled by different growth conditions and wet-etching times. Our experimental results reveal that the D0X shift depends on the diameter of the GaN NRs after hydrogenation. The results clearly demonstrate that the hydrogenation leads to band bending of GaN NRs as compensated by hydrogen ions, which causes a red-shift in the D0X emission.

A study of the red-shift of a neutral donor bound exciton in GaN nanorods by hydrogenation.

PubMed

Park, Byung-Guon; Lee, Sang-Tae; Reddeppa, Maddaka; Kim, Moon-Deock; Oh, Jae-Eung; Lee, Sang-Kwon

2017-09-08

In this paper we account for the physics behind the exciton peak shift in GaN nanorods (NRs) due to hydrogenation. GaN NRs were selectively grown on a patterned Ti/Si(111) substrate using plasma-assisted molecular beam epitaxy, and the effect of hydrogenation on their optical properties was investigated in detail using low-temperature photoluminescence measurements. Due to hydrogenation, the emissions corresponding to the donor-acceptor pair and yellow luminescence in GaN NRs were strongly suppressed, while the emission corresponding to the neutral to donor bound exciton (D 0 X) exhibited red-shift. Thermal annealing of hydrogenated GaN NRs demonstrated the recovery of the D 0 X and deep level emission. To determine the nature of the D 0 X peak shift due to hydrogenation, comparative studies were carried out on various diameters of GaN NRs, which can be controlled by different growth conditions and wet-etching times. Our experimental results reveal that the D 0 X shift depends on the diameter of the GaN NRs after hydrogenation. The results clearly demonstrate that the hydrogenation leads to band bending of GaN NRs as compensated by hydrogen ions, which causes a red-shift in the D 0 X emission.

Diamagnetic susceptibility of a hydrogenic donor in a group IV-VI quantum dot-quantum well heterostructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saravanamoorthy, S. N.; Peter, A. John, E-mail: a.john.peter@gmail.com

2016-05-23

Electronic properties of a hydrogenic donor impurity in a CdSe/Pb{sub 0.8}Cd{sub 0.2}Se/CdSe quantum dot quantum well system are investigated for various radii of core with shell materials. Confined energies are obtained taking into account the geometrical size of the system and thereby the donor binding energies are found. The diamagnetic susceptibility is estimated for a confined shallow donor in the well system. The results show that the diamagnetic susceptibility strongly depends on core and shell radii and it is more sensitive to variations of the geometrical size of the well material.

Hydrogen donors and acceptors and basic amino acids jointly contribute to carcinogenesis.

PubMed

Tang, Man; Zhou, Yanchao; Li, Yiqi; Zou, Juntong; Yang, Beicheng; Cai, Li; Zhang, Xuelan; Liu, Qiuyun

2017-01-01

A hypothesis is postulated that high content of hydrogen donors and acceptors, and basic amino acids cause the intracellular trapping of the H + and Cl - ions, which increases cancer risks as local formation of HCl is mutagenic to DNA. Other cations such as Ca 2+ , and weak acids such as short-chain organic acids may attenuate the intracellular gathering of the H + and Cl - , two of the most abundant ions in the cells. Current data on increased cancer risks in diabetic and obese patients are consistent with the assumption that hydrogen bonding propensity on glucose, triglycerides and other molecules is among the causative factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental Evidence for Hydrogen Tunneling when the Isotopic Arrhenius Prefactor (AH/AD) is Unity

PubMed Central

Sharma, Sudhir C.; Klinman, Judith P.

2009-01-01

The temperature dependence of the kinetic isotope effect (KIE) is one of the major tools used for the investigation of hydrogen tunneling in condensed phase. Hydrogen transfer reactions displaying isotopic Arrhenius prefactor ratios (AH/AD) of unity are generally ascribed to a semi-classical mechanism. Here, we have identified a double mutant of soybean lipoxygenase (SLO-1, an enzyme previously shown to follow quantum mechanical hydrogen tunneling), that displays an AH/AD of unity and highly elevated (non-classical) KIEs. This observation highlights the shortcoming of assigning a hydrogen transfer reaction to a semi-classical model based solely on an Arrhenius prefactor ratio. PMID:19061319

Development of an Mg-Based Alloy with a Hydrogen-Storage Capacity over 6 wt% by Adding Graphene

NASA Astrophysics Data System (ADS)

Choi, Eunho; Kwak, Young Jun; Song, Myoung Youp

2018-06-01

Graphene (multilayer graphene) was chosen as an additive to improve the hydrogen uptake and release properties of magnesium (Mg). Five weight percent of graphene was added to pre-milled Mg by milling in hydrogen (reaction-involving milling). The hydrogen uptake and release properties of the graphene-added Mg were investigated. The activation of Mg-5graphene, which was prepared by adding 5 wt% graphene to Mg pre-milled for 24 h, was completed after the second cycle (cycle number, CN = 2). Mg-5graphene had a high effective hydrogen-storage capacity (the quantity of hydrogen absorbed for 60 min) of 6.21 wt% at CN = 3 at 593 K in 12 bar H2. At CN = 1, Mg-5graphene released 0.46 wt% hydrogen for 10 min and 4.99 wt% hydrogen for 60 min. Milling in hydrogen is believed to create defects (leading to facilitation of nucleation), produce cracks and clean surfaces (leading to increase in reactivity), and decrease particle size (leading to diminution of diffusion distances or increasing the flux of diffusing hydrogen atoms). The added graphene is believed to have helped the sample have higher hydrogen uptake and release rates, weakly but partly, by dispersing heat rapidly.

Binding energy and photoionization cross-section of hydrogen-like donor impurity in strongly oblate ellipsoidal quantum dot

NASA Astrophysics Data System (ADS)

Hayrapetyan, D. B.; Ohanyan, G. L.; Baghdasaryan, D. A.; Sarkisyan, H. A.; Baskoutas, S.; Kazaryan, E. M.

2018-01-01

Hydrogen-like donor impurity states in strongly oblate ellipsoidal quantum dot have been studied. The hydrogen-like donor impurity states are investigated within the framework of variational method. The trial wave function constructed on the base of wave functions of the system without impurity. The dependence of the energy and binding energy for the ground and first excited states on the geometrical parameters of the ellipsoidal quantum dot and on the impurity position have been calculated. The behavior of the oscillator strength for different angles of incident light and geometrical parameters have been revealed. Photoionization cross-section of the electron transitions from the impurity ground state to the size-quantized ground and first excited states have been studied. The effects of impurity position and the geometrical parameters of the ellipsoidal quantum dot on the photoionization cross section dependence on the photon energy have been considered.

Creating Graphitic Carbon Nitride Based Donor-π-Acceptor-π-Donor Structured Catalysts for Highly Photocatalytic Hydrogen Evolution.

PubMed

Li, Kui; Zhang, Wei-De

2018-03-01

Conjugated polymers with tailored donor-acceptor units have recently attracted considerable attention in organic photovoltaic devices due to the controlled optical bandgap and retained favorable separation of charge carriers. Inspired by these advantages, an effective strategy is presented to solve the main obstructions of graphitic carbon nitride (g-C 3 N 4 ) photocatalyst for solar energy conversion, that is, inefficient visible light response and insufficient separation of photogenerated electrons and holes. Donor-π-acceptor-π-donor polymers are prepared by incorporating 4,4'-(benzoc 1,2,5 thiadiazole-4,7-diyl) dianiline (BD) into the g-C 3 N 4 framework (UCN-BD). Benefiting from the visible light band tail caused by the extended π conjugation, UCN-BD possesses expanded visible light absorption range. More importantly, the BD monomer also acts as an electron acceptor, which endows UCN-BD with a high degree of intramolecular charge transfer. With this unique molecular structure, the optimized UCN-BD sample exhibits a superior performance for photocatalytic hydrogen evolution upon visible light illumination (3428 µmol h -1 g -1 ), which is nearly six times of that of the pristine g-C 3 N 4 . In addition, the photocatalytic property remains stable for six cycles in 3 d. This work provides an insight into the synthesis of g-C 3 N 4 -based D-π-A-π-D systems with highly visible light response and long lifetime of intramolecular charge carriers for solar fuel production. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancement in Organic Photovoltaic Efficiency through the Synergistic Interplay of Molecular Donor Hydrogen Bonding and -Stacking

DOE PAGES

Shewmon, Nathan; Watkins, Davita; Galindo, Johan; ...

2015-07-20

For organic photovoltaic (OPV) cells based on the bulk heterojunction (BHJ) structure, it remains challenging to rationally control the degree of phase separation and percolation within blends of donors and acceptors to secure optimal charge separation and transport. Reported is a bottom-up, supramolecular approach to BHJ OPVs wherein tailored hydrogen bonding (H-bonding) interactions between π-conjugated electron donor molecules encourage formation of vertically aligned donor π-stacks while simultaneously suppressing lateral aggregation; the programmed arrangement facilitates fine mixing with fullerene acceptors and efficient charge transport. The approach is illustrated using conventional linear or branched quaterthiophene donor chromophores outfitted with terminal functional groupsmore » that are either capable or incapable of self-complementary H-bonding. When applied to OPVs, the H-bond capable donors yield a twofold enhancement in power conversion efficiency relative to the comparator systems, with a maximum external quantum efficiency of 64%. H-bond promoted assembly results in redshifted absorption (in neat films and donor:C 60 blends) and enhanced charge collection efficiency despite disparate donor chromophore structure. Both features positively impact photocurrent and fill factor in OPV devices. Film structural characterization by atomic force microscopy, transmission electron microscopy, and grazing incidence wide angle X-ray scattering reveals a synergistic interplay of lateral H-bonding interactions and vertical π-stacking for directing the favorable morphology of the BHJ.« less

Progress in donor assisted coal liquefaction: Hydroaromatic compound formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kottenstette, R.J.; Stephens, H.P.

1993-12-31

The role of hydrogen donor compounds in coal liquefaction has been extensively investigated since the mid 1960`s using model compounds and process derived hydrogen donor solvents. Our recent research and that of other investigators have shown that two model compounds in particular have great efficacy in solvating low rank coals. 1,2,3,10b tetrahydrofluoranthene (H{sub 4}Fl) and 1,2,3,6,7,8 hexahydropyrene (H{sub 6}Py) have been used to dissolve Wyodak coal to > 95% soluble material as measured by tetrahydrofuran (THF). Although these hydrogen donors are very effective, they may not be found in any significant concentrations in actual liquefaction process recycle solvents. Therefore, studiesmore » with process derived recycle materials are necessary to understand donor solvent chemistry. The objective of this paper is to present results of solvent hydrogenation experiments using heavy distillate solvents produced during testing at the Wilsonville Advanced Coal Liquefaction Test Facility. We evaluated the impact of hydrogenation conditions upon hydrogen donor formation in process derived distillates and compared these process derived solvents with the highly effective H{sub 4}Fl and H{sub 6}Py donors in coal liquefaction tests. This paper presents data on reaction conditions used for distillate hydrotreating and subsequent coal liquefaction, with an aim toward understanding the relationship between reaction conditions and donor solvent quality in recycle distillates.« less

Chromatographic Assessment of Hydrogen-Bond Donating Ability

DTIC Science & Technology

1993-04-22

hydrogen-bond donors used in cocrystallizations . Hydrogen-bond donor solutes are chromatographed on a poly(vinylpyridine-divinylbenzene) column under...provides an a priori measure of the hydrogen- bond acidity of a potential cocrystal component. 20 DISTRIBUTION /AVAILABILITY OF ABSTRACT 21 ABSTRACT...general heuristic principle that has guided our cocrystallization studies is "the best hydrogen-bond donor hydrogen bonds to the best hydrogen-bond acceptor

Synchronous microbial vanadium (V) reduction and denitrification in groundwater using hydrogen as the sole electron donor.

PubMed

Jiang, Yufeng; Zhang, Baogang; He, Chao; Shi, Jiaxin; Borthwick, Alistair G L; Huang, Xueyang

2018-05-21

Groundwater co-contaminated by vanadium (V) (V(V)) and nitrate requires efficient remediation to prevent adverse environmental impacts. However, little is known about simultaneous bio-reductions of V(V) and nitrate supported by gaseous electron donors in aquifers. This study is among the first to examine microbial V(V) reduction and denitrification with hydrogen as the sole electron donor. V(V) removal efficiency of 91.0 ± 3.2% was achieved in test bioreactors within 7 d, with synchronous, complete removal of nitrate. V(V) was reduced to V(IV), which precipitated naturally under near-neutral conditions, and nitrate tended to be converted to nitrogen, both of which processes helped to purify the groundwater. Volatile fatty acids (VFAs) were produced from hydrogen oxidation. High-throughput 16S rRNA gene sequencing and metagenomic analyses revealed the evolutionary behavior of microbial communities and functional genes. The genera Dechloromonas and Hydrogenophaga promoted bio-reductions of V(V) and nitrate directly coupled to hydrogen oxidation. Enriched Geobacter and denitrifiers also indicated synergistic mechanism, with VFAs acting as organic carbon sources for heterotrophically functional bacteria while reducing V(V) and nitrate. These findings are likely to be useful in revealing biogeochemical fates of V(V) and nitrate in aquifer and developing technology for removing them simultaneously from groundwater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrogen donor solvent coal liquefaction process

DOEpatents

Plumlee, Karl W.

1978-01-01

An indigenous hydrocarbon product stream boiling within a range of from about C.sub.1 -700.degree. F., preferably C.sub.1 -400.degree. F., is treated to produce an upgraded hydrocarbon fuel component and a component which can be recycled, with a suitable donor solvent, to a coal liquefaction zone to catalyze the reaction. In accordance therewith, a liquid hydrocarbon fraction with a high end boiling point range up to about 700.degree. F., preferably up to about 400.degree. F., is separated from a coal liquefaction zone effluent, the separated fraction is contacted with an alkaline medium to provide a hydrocarbon phase and an aqueous extract phase, the aqueous phase is neutralized, and contacted with a peroxygen compound to convert indigenous components of the aqueous phase of said hydrocarbon fraction into catalytic components, such that the aqueous stream is suitable for recycle to the coal liquefaction zone. Naturally occurring phenols and alkyl substituted phenols, found in the aqueous phase, are converted, by the addition of hydroxyl constituents to phenols, to dihydroxy benzenes which, as disclosed in copending Application Ser. Nos. 686,813 now U.S. Pat. No. 4,049,536; 686,814 now U.S. Pat. No. 4,049,537; 686,827 now U.S. Pat. No. 4,051,012 and 686,828, K. W. Plumlee et al, filed May 17, 1976, are suitable hydrogen transfer catalysts.

Relationship of Hydrogen Bioavailability to Chromate Reduction in Aquifer Sediments

PubMed Central

Marsh, Tamara L.; McInerney, Michael J.

2001-01-01

Biological Cr(VI) reduction was studied in anaerobic sediments from an aquifer in Norman, Okla. Microcosms containing sediment and mineral medium were amended with various electron donors to determine those most important for biological Cr(VI) reduction. Cr(VI) (about 340 μM) was reduced with endogenous substrates (no donor), or acetate was added. The addition of formate, hydrogen, and glucose stimulated Cr(VI) reduction compared with reduction in unamended controls. From these sediments, an anaerobic Cr(VI)-utilizing enrichment was obtained that was dependent upon hydrogen for both growth and Cr(VI) reduction. No methane was produced by the enrichment, which reduced about 750 μM Cr(VI) in less than six days. The dissolved hydrogen concentration was used as an indicator of the terminal electron accepting process occurring in the sediments. Microcosms with sediments, groundwater, and chromate metabolized hydrogen to a concentration below the detection limits of the mercury vapor gas chromatograph. In microcosms without chromate, the hydrogen concentration was about 8 nM, a concentration comparable to that under methanogenic conditions. When these microcosms were amended with 500 μM Cr(VI), the dissolved hydrogen concentration quickly fell below the detection limits. These results showed that the hydrogen concentration under chromate-reducing conditions became very low, as low as that reported under nitrate- and manganese-reducing conditions, a result consistent with the free energy changes for these reactions. The utilization of formate, lactate, hydrogen, and glucose as electron donors for Cr(VI) reduction indicates that increasing the availability of hydrogen results in a greater capacity for Cr(VI) reduction. This conclusion is supported by the existence of an enrichment dependent upon hydrogen for growth and Cr(VI) reduction. PMID:11282599

Hydrogen atom donor compounds as contrast enhancers for black-and-white photothermographic and thermographic elements

DOEpatents

Harring, Lori S.; Simpson, Sharon M.; Sansbury, Francis H.

1997-01-01

Hydrogen atom donor compounds are useful as contrast enhancers when used in combination with (i) hindered phenol developers, and (ii) trityl hydrazide and/or formyl-phenyl hydrazine co-developers, to produce ultra-high contrast black-and-white photothermographic and thermographic elements. The photothermographic and thermographic elements may be used as a photomask in a process where there is a subsequent exposure of an ultraviolet or short wavelength visible radiation-sensitive imageable medium.

Tunnel barrier design in donor nanostructures defined by hydrogen-resist lithography

NASA Astrophysics Data System (ADS)

Pascher, Nikola; Hennel, Szymon; Mueller, Susanne; Fuhrer, Andreas

2016-08-01

A four-terminal donor quantum dot (QD) is used to characterize potential barriers between degenerately doped nanoscale contacts. The QD is fabricated by hydrogen-resist lithography on Si(001) in combination with n-type doping by phosphine. The four contacts have different separations (d = 9, 12, 16 and 29 nm) to the central 6 nm × 6 nm QD island, leading to different tunnel and capacitive coupling. Cryogenic transport measurements in the Coulomb-blockade (CB) regime are used to characterize these tunnel barriers. We find that field enhancement near the apex of narrow dopant leads is an important effect that influences both barrier breakdown and the magnitude of the tunnel current in the CB transport regime. From CB-spectroscopy measurements, we extract the mutual capacitances between the QD and the four contacts, which scale inversely with the contact separation d. The capacitances are in excellent agreement with numerical values calculated from the pattern geometry in the hydrogen resist. Furthermore, we show that by engineering the source-drain tunnel barriers to be asymmetric, we obtain a much simpler excited-state spectrum of the QD, which can be directly linked to the orbital single-particle spectrum.

Effect of metal ions on the reactions of the cumyloxyl radical with hydrogen atom donors. Fine control on hydrogen abstraction reactivity determined by Lewis acid-base interactions.

PubMed

Salamone, Michela; Mangiacapra, Livia; DiLabio, Gino A; Bietti, Massimo

2013-01-09

A time-resolved kinetic study on the effect of metal ions (M(n+)) on hydrogen abstraction reactions from C-H donor substrates by the cumyloxyl radical (CumO(•)) was carried out in acetonitrile. Metal salt addition was observed to increase the CumO(•) β-scission rate constant in the order Li(+) > Mg(2+) > Na(+). These effects were explained in terms of the stabilization of the β-scission transition state determined by Lewis acid-base interactions between M(n+) and the radical. When hydrogen abstraction from 1,4-cyclohexadiene was studied in the presence of LiClO(4) and Mg(ClO(4))(2), a slight increase in rate constant (k(H)) was observed indicating that interaction between M(n+) and CumO(•) can also influence, although to a limited extent, the hydrogen abstraction reactivity of alkoxyl radicals. With Lewis basic C-H donors such as THF and tertiary amines, a decrease in k(H) with increasing Lewis acidity of M(n+) was observed (k(H)(MeCN) > k(H)(Li(+)) > k(H)(Mg(2+))). This behavior was explained in terms of the stronger Lewis acid-base interaction of M(n+) with the substrate as compared to the radical. This interaction reduces the degree of overlap between the α-C-H σ* orbital and a heteroatom lone-pair, increasing the C-H BDE and destabilizing the carbon centered radical formed after abstraction. With tertiary amines, a >2-order of magnitude decrease in k(H) was measured after Mg(ClO(4))(2) addition up to a 1.5:1 amine/Mg(ClO(4))(2) ratio. At higher amine concentrations, very similar k(H) values were measured with and without Mg(ClO(4))(2). These results clearly show that with strong Lewis basic substrates variations in the nature and concentration of M(n+) can dramatically influence k(H), allowing for a fine control of the substrate hydrogen atom donor ability, thus providing a convenient method for C-H deactivation. The implications and generality of these findings are discussed.

Do Halogen–Hydrogen Bond Donor Interactions Dominate the Favorable Contribution of Halogens to Ligand–Protein Binding?

PubMed Central

2017-01-01

Halogens are present in a significant number of drugs, contributing favorably to ligand–protein binding. Currently, the contribution of halogens, most notably chlorine and bromine, is largely attributed to halogen bonds involving favorable interactions with hydrogen bond acceptors. However, we show that halogens acting as hydrogen bond acceptors potentially make a more favorable contribution to ligand binding than halogen bonds based on quantum mechanical calculations. In addition, bioinformatics analysis of ligand–protein crystal structures shows the presence of significant numbers of such interactions. It is shown that interactions between halogens and hydrogen bond donors (HBDs) are dominated by perpendicular C–X···HBD orientations. Notably, the orientation dependence of the halogen–HBD (X–HBD) interactions is minimal over greater than 100° with favorable interaction energies ranging from −2 to −14 kcal/mol. This contrasts halogen bonds in that X–HBD interactions are substantially more favorable, being comparable to canonical hydrogen bonds, with a smaller orientation dependence, such that they make significant, favorable contributions to ligand–protein binding and, therefore, should be actively considered during rational ligand design. PMID:28657759

Facile and Promising Method for Michael Addition of Indole and Pyrrole to Electron-Deficient trans-β-Nitroolefins Catalyzed by a Hydrogen Bond Donor Catalyst Feist's Acid and Preliminary Study of Antimicrobial Activity

PubMed Central

Al Majid, Abdullah M. A.; Islam, Mohammad Shahidul; Barakat, Assem; Al-Agamy, Mohamed H. M.; Naushad, Mu.

2014-01-01

The importance of cooperative hydrogen-bonding effects has been demonstrated using novel 3-methylenecyclopropane-1,2-dicarboxylic acid (Feist's acid (FA)) as hydrogen bond donor catalysts for the addition of indole and pyrrole to trans-β-nitrostyrene derivatives. Because of the hydrogen bond donor (HBD) ability, Feist's acid (FA) has been introduced as a new class of hydrogen bond donor catalysts for the activation of nitroolefin towards nucleophilic substitution reaction. It has effectively catalyzed the Michael addition of indoles and pyrrole to β-nitroolefins under optimum reaction condition to furnish the corresponding Michael adducts in good to excellent yields (up to 98%). The method is general, atom-economical, convenient, and eco-friendly and could provide excellent yields and regioselectivities. Some newly synthesized compounds were for examined in vitro antimicrobial activity and their preliminary results are reported. PMID:24574906

Molecular dynamics study of the encapsulation capability of a PCL-PEO based block copolymer for hydrophobic drugs with different spatial distributions of hydrogen bond donors and acceptors.

PubMed

Patel, Sarthak K; Lavasanifar, Afsaneh; Choi, Phillip

2010-03-01

Molecular dynamics simulation was used to study the potential of using a block copolymer containing three poly(epsilon-caprolactone) (PCL) blocks of equal length connected to one end of a poly(ethylene oxide) (PEO) block, designated as PEO-b-3PCL, to encapsulate two classes of hydrophobic drugs with distinctively different molecular structures. In particular, the first class of drugs consisted of two cucurbitacin drugs (CuB and CuI) that contain multiple hydrogen bond donors and acceptors evenly distributed on their molecules while the other class of drugs (fenofibrate and nimodipine) contain essentially only clustered hydrogen bond acceptors. In the case of cucurbitacin drugs, the results showed that PEO-b-3PCL lowered the Flory-Huggins interaction parameters (chi) considerably (i.e., increased the drug solubility) compared to the linear di-block copolymer PEO-b-PCL with the same PCL/PEO (w/w) ratio of 1.0. However, the opposite effect was observed for fenofibrate and nimodipine. Analysis of the intermolecular interactions indicates that the number of hydrogen bonds formed between the three PCL blocks and cucurbitacin drugs is significantly higher than that of the linear di-block copolymer. On the other hand, owing to the absence of hydrogen bond donors and the clustering of the hydrogen bond acceptors on the fenofibrate and nimodipine molecules, this significantly reduces the number of hydrogen bonds formed in the multi-PCL block environment, leading to unfavourable chi values. The findings of the present work suggest that multi-hydrophobic block architecture could potentially increase the drug loading for hydrophobic drugs with structures containing evenly distributed multiple hydrogen bond donors and acceptors. (c) 2009 Elsevier Ltd. All rights reserved.

Quasiclassical description of the nearest-neighbor hopping dc conduction via hydrogen-like donors in intermediately compensated GaAs crystals

NASA Astrophysics Data System (ADS)

Poklonski, N. A.; Vyrko, S. A.; Zabrodskii, A. G.

2010-08-01

Expressions for the pre-exponential factor σ3 and the thermal activation energy ɛ3 of hopping electric conductivity of electrons via hydrogen-like donors in n-type gallium arsenide are obtained in the quasiclassical approximation. Crystals with the donor concentration N and the acceptor concentration KN at the intermediate compensation ratio K (approximately from 0.25 to 0.75) are considered. We assume that the donors in the charge states (0) and (+1) and the acceptors in the charge state (-1) form a joint nonstoichiometric simple cubic 'sublattice' within the crystalline matrix. In such sublattice the distance between nearest impurity atoms is Rh = [(1 + K)N]-1/3 which is also the length of an electron hop between donors. To take into account orientational disorder of hops we assume that the impurity sublattice randomly and smoothly changes orientation inside a macroscopic sample. Values of σ3(N) and ɛ3(N) calculated for the temperature of 2.5 K agree with known experimental data at the insulator side of the insulator-metal phase transition.

Fixation of carbon dioxide by a hydrogen-oxidizing bacterium for value-added products.

PubMed

Yu, Jian

2018-06-09

With rapid technology progress and cost reduction, clean hydrogen from water electrolysis driven by renewable powers becomes a potential feedstock for CO 2 fixation by hydrogen-oxidizing bacteria. Cupriavidus necator (formally Ralstonia eutropha), a representative member of the lithoautotrophic prokaryotes, is a promising producer of polyhydroxyalkanoates and single cell proteins. This paper reviews the fundamental properties of the hydrogen-oxidizing bacterium, the metabolic activities under limitation of individual gases and nutrients, and the value-added products from CO 2 , including the products with large potential markets. Gas fermentation and bioreactor safety are discussed for achieving high cell density and high productivity of desired products under chemolithotrophic conditions. The review also updates the recent research activities in metabolic engineering of C. necator to produce novel metabolites from CO 2 .

Uranium reduction and microbial community development in response to stimulation with different electron donors.

PubMed

Barlett, Melissa; Moon, Hee Sun; Peacock, Aaron A; Hedrick, David B; Williams, Kenneth H; Long, Philip E; Lovley, Derek; Jaffe, Peter R

2012-07-01

Stimulating microbial reduction of soluble U(VI) to less soluble U(IV) shows promise as an in situ bioremediation strategy for uranium contaminated groundwater, but the optimal electron donors for promoting this process have yet to be identified. The purpose of this study was to better understand how the addition of various electron donors to uranium-contaminated subsurface sediments affected U(VI) reduction and the composition of the microbial community. The simple electron donors, acetate or lactate, or the more complex donors, hydrogen-release compound (HRC) or vegetable oil, were added to the sediments incubated in flow-through columns. The composition of the microbial communities was evaluated with quantitative PCR probing specific 16S rRNA genes and functional genes, phospholipid fatty acid analysis, and clone libraries. All the electron donors promoted U(VI) removal, even though the composition of the microbial communities was different with each donor. In general, the overall biomass, rather than the specific bacterial species, was the factor most related to U(VI) removal. Vegetable oil and HRC were more effective in stimulating U(VI) removal than acetate. These results suggest that the addition of more complex organic electron donors could be an excellent option for in situ bioremediation of uranium-contaminated groundwater.

Comparison of lactate, formate, and propionate as hydrogen donors for the reductive dehalogenation of trichloroethene in a continuous-flow column

NASA Astrophysics Data System (ADS)

Azizian, Mohammad F.; Marshall, Ian P. G.; Behrens, Sebastian; Spormann, Alfred M.; Semprini, Lewis

2010-04-01

A continuous-flow column study was conducted to analyze the reductive dehalogenation of trichloroethene (TCE) with aquifer material with high content of iron oxides. The column was bioaugmented with the Point Mugu (PM) culture, which is a mixed microbial enrichment culture capable of completely transforming TCE to ethene (ETH). We determined whether lactate, formate, or propionate fermentation resulted in more effective dehalogenation. Reductive dehalogenation, fermentation, and sulfate, Fe(III), and Mn(IV) reduction were all exhibited within the column. Different steady-states of dehalogenation were achieved based on the concentration of substrates added, with effective transformation to ETH obtained when ample electron donor equivalents were provided. Most of the metabolic reducing equivalents were channeled to sulfate, Fe(III), and Mn(IV) reduction. When similar electron reducing equivalents were added, the most effective dehalogenation was achieved with formate, with 14% of the electron equivalents going towards dehalogenation reactions, compared to 6.5% for lactate and 9.6% for propionate. Effective dehalogenation was maintained over 1000 days of column operation. Over 90% of electron equivalents added could be accounted for by the different electron accepting processes in the column, with 50% associated with soluble and precipitated Fe(II) and Mn(II). Bulk Fe(III) and Mn(IV) reduction was rather associated with lactate and propionate addition than formate addition. Sulfate reduction was a competing electron acceptor reaction with all three electron donors. DNA was extracted from solid coupon samples obtained during the course of the experiment and analyzed using 16S rRNA gene clone libraries and quantitative PCR. Lactate and propionate addition resulted in a significant increase in Geobacter, Spirochaetes, and Desulfitobacterium phylotypes relative to " Dehalococcoides" when compared to formate addition. Results from the molecular biological analyses support

Design principles for hydrogen evolution reaction catalyst materials

DOE PAGES

Strmcnik, Dusan; Lopes, Pietro Papa; Genorio, Bostjan; ...

2016-04-19

Design and synthesis of active, stable and cost-effective materials for efficient hydrogen production (hydrogen evolution reaction, HER) is of paramount importance for the successful deployment of hydrogen -based alternative energy technologies. The HER, seemingly one of the simplest electrochemical reactions, has served for decades to bridge the gap between fundamental electrocatalysis and practical catalyst design. However, there are still many open questions that need to be answered before it would be possible to claim that design principles of catalyst materials are fully developed for the efficient hydrogen production. Here in this review, by summarizing key results for the HER onmore » well-characterized electrochemical interfaces in acidic and alkaline media, we have broadened our understanding of the HER in the whole range of pH by considering three main parameters: the nature of the proton donor (H 3O + in acid and H 2O in alkaline), the energy of adsorption of H ad and OH ad, and the presence of spectator species. Simply by considering these three parameters we show that great deal has already been learned and new trends are beginning to emerge, giving some predictive ability with respect to the nature of electrochemical interface and electrocatalytic activity of the HER.« less

Mechanochemical hydrogenation of coal

DOEpatents

Yang, Ralph T.; Smol, Robert; Farber, Gerald; Naphtali, Leonard M.

1981-01-01

Hydrogenation of coal is improved through the use of a mechanical force to reduce the size of the particulate coal simultaneously with the introduction of gaseous hydrogen, or other hydrogen donor composition. Such hydrogen in the presence of elemental tin during this one-step size reduction-hydrogenation further improves the yield of the liquid hydrocarbon product.

Solicited kidney donors: Are they coerced?

PubMed

Serur, David; Bretzlaff, Gretchen; Christos, Paul; Desrosiers, Farrah; Charlton, Marian

2015-12-01

Most non-directed donors (NDDs) decide to donate on their own and contact the transplant centre directly. Some NDDs decide to donate in response to community solicitation such as newspaper ads or donor drives. We wished to explore whether subtle coercion might be occurring in such NDDs who are part of a larger community. One successful organization in a community in Brooklyn, NY, provides about 50 NDDs per year for recipients within that community. The donors answer ads in local papers and attend donor drives. Herein, we evaluated the physical and emotional outcomes of community-solicited NDDs in comparison to traditional NDDs who come from varied communities and are not responding to a specific call for donation. An assessment of coercion was used as well. © 2015 Asian Pacific Society of Nephrology.

Comparison of lactate, formate, and propionate as hydrogen donors for the reductive dehalogenation of trichloroethene in a continuous-flow column.

PubMed

Azizian, Mohammad F; Marshall, Ian P G; Behrens, Sebastian; Spormann, Alfred M; Semprini, Lewis

2010-04-01

A continuous-flow column study was conducted to analyze the reductive dehalogenation of trichloroethene (TCE) with aquifer material with high content of iron oxides. The column was bioaugmented with the Point Mugu (PM) culture, which is a mixed microbial enrichment culture capable of completely transforming TCE to ethene (ETH). We determined whether lactate, formate, or propionate fermentation resulted in more effective dehalogenation. Reductive dehalogenation, fermentation, and sulfate, Fe(III), and Mn(IV) reduction were all exhibited within the column. Different steady-states of dehalogenation were achieved based on the concentration of substrates added, with effective transformation to ETH obtained when ample electron donor equivalents were provided. Most of the metabolic reducing equivalents were channeled to sulfate, Fe(III), and Mn(IV) reduction. When similar electron reducing equivalents were added, the most effective dehalogenation was achieved with formate, with 14% of the electron equivalents going towards dehalogenation reactions, compared to 6.5% for lactate and 9.6% for propionate. Effective dehalogenation was maintained over 1000 days of column operation. Over 90% of electron equivalents added could be accounted for by the different electron accepting processes in the column, with 50% associated with soluble and precipitated Fe(II) and Mn(II). Bulk Fe(III) and Mn(IV) reduction was rather associated with lactate and propionate addition than formate addition. Sulfate reduction was a competing electron acceptor reaction with all three electron donors. DNA was extracted from solid coupon samples obtained during the course of the experiment and analyzed using 16S rRNA gene clone libraries and quantitative PCR. Lactate and propionate addition resulted in a significant increase in Geobacter, Spirochaetes, and Desulfitobacterium phylotypes relative to "Dehalococcoides" when compared to formate addition. Results from the molecular biological analyses support

Absence of beta-amyloid in cortical cataracts of donors with and without Alzheimer's disease.

PubMed

Michael, Ralph; Rosandić, Jurja; Montenegro, Gustavo A; Lobato, Elvira; Tresserra, Francisco; Barraquer, Rafael I; Vrensen, Gijs F J M

2013-01-01

Eye lenses from human donors with and without Alzheimer's disease (AD) were studied to evaluate the presence of amyloid in cortical cataract. We obtained 39 lenses from 21 postmortem donors with AD and 15 lenses from age-matched controls provided by the Banco de Ojos para Tratamientos de la Ceguera (Barcelona, Spain). For 17 donors, AD was clinically diagnosed by general physicians and for 4 donors the AD diagnosis was neuropathologically confirmed. Of the 21 donors with AD, 6 had pronounced bilateral cortical lens opacities and 15 only minor or no cortical opacities. As controls, 7 donors with pronounced cortical opacities and 8 donors with almost transparent lenses were selected. All lenses were photographed in a dark field stereomicroscope. Histological sections were analyzed using a standard and a more sensitive Congo red protocol, thioflavin staining and beta-amyloid immunohistochemistry. Brain tissue from two donors, one with cerebral amyloid angiopathy and another with advanced AD-related changes and one cornea with lattice dystrophy were used as positive controls for the staining techniques. Thioflavin, standard and modified Congo red staining were positive in the control brain tissues and in the dystrophic cornea. Beta-amyloid immunohistochemistry was positive in the brain tissues but not in the cornea sample. Lenses from control and AD donors were, without exception, negative after Congo red, thioflavin, and beta-amyloid immunohistochemical staining. The results of the positive control tissues correspond well with known observations in AD, amyloid angiopathy and corneas with lattice dystrophy. The absence of staining in AD and control lenses with the techniques employed lead us to conclude that there is no beta-amyloid in lenses from donors with AD or in control cortical cataracts. The inconsistency with previous studies of Goldstein et al. (2003) and Moncaster et al. (2010), both of which demonstrated positive Congo red, thioflavin, and beta

Pendant Hydrogen-Bond Donors in Cobalt Catalysts Independently Enhance CO2 Reduction

PubMed Central

2018-01-01

The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO2 to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO2 reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO2, and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO2, but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO2 substrate. PMID:29632886

Pendant Hydrogen-Bond Donors in Cobalt Catalysts Independently Enhance CO2 Reduction.

PubMed

Chapovetsky, Alon; Welborn, Matthew; Luna, John M; Haiges, Ralf; Miller, Thomas F; Marinescu, Smaranda C

2018-03-28

The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO 2 to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO 2 reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO 2 , and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO 2 , but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO 2 substrate.

A new photostabilizer: Hydrogenated benzoin derivatives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamaguchi, K.; Ohkatsu, Y.

1993-12-31

It is found that synergistic effects based on combined use of HALS (hindered Amine Light Stabilizers) with phenolic antioxidants consist of the action of HALS as hydrogen donor to quinones, derived from the phenol in autoxidation, excited by uv light. The finding has been realized as a new photostabilizer of hydrogenated benzoin derivatives. They are generally characterized by multifunctions. The o,o`-dihydroxyl-substituted derivatives inter alia extend the life of a phenolic antioxidant co-used, as hydrogen donor, as well as ultimately act as uv absorber.

Reinforced self-assembly of donor-acceptor π-conjugated molecules to DNA templates by dipole-dipole interactions together with complementary hydrogen bonding interactions for biomimetics.

PubMed

Yang, Wanggui; Chen, Yali; Wong, Man Shing; Lo, Pik Kwan

2012-10-08

One of the most important criteria for the successful DNA-templated polymerization to generate fully synthetic biomimetic polymers is to design the complementary structural monomers, which assemble to the templates strongly and precisely before carrying polymerization. In this study, water-soluble, laterally thymine-substituted donor-acceptor π-conjugated molecules were designed and synthesized to self-assemble with complementary oligoadenines templates, dA(20) and dA(40), into stable and tubular assemblies through noncovalent interactions including π-π stacking, dipole-dipole interactions, and the complementary adenine-thymine (A-T) hydrogen-bonding. UV-vis, fluorescence, circular dichroism (CD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques were used to investigate the formation of highly robust nanofibrous structures. Our results have demonstrated for the first time that the dipole-dipole interactions are stronger and useful to reinforce the assembly of donor-acceptor π-conjugated molecules to DNA templates and the formation of the stable and robust supramolecular nanofibrous complexes together with the complementary hydrogen bonding interactions. This provides an initial step toward DNA-templated polymerization to create fully synthetic DNA-mimetic polymers for biotechnological applications. This study also presents an opportunity to precisely position donor-acceptor type molecules in a controlled manner and tailor-make advanced materials for various biotechnological applications.

Ad Integrum Functional and Volumetric Recovery in Right Lobe Living Donors: Is It Really Complete 1 Year After Donor Hepatectomy?

PubMed

Duclos, J; Bhangui, P; Salloum, C; Andreani, P; Saliba, F; Ichai, P; Elmaleh, A; Castaing, D; Azoulay, D

2016-01-01

The partial liver's ability to regenerate both as a graft and remnant justifies right lobe (RL) living donor liver transplantation. We studied (using biochemical and radiological parameters) the rate, extent of, and predictors of functional and volumetric recovery of the remnant left liver (RLL) during the first year in 91 consecutive RL donors. Recovery of normal liver function (prothrombin time [PT] ≥70% of normal and total bilirubin [TB] ≤20 µmol/L), liver volumetric recovery, and percentage RLL growth were analyzed. Normal liver function was regained by postoperative day's 7, 30, and 365 in 52%, 86%, and 96% donors, respectively. Similarly, mean liver volumetric recovery was 64%, 71%, and 85%; whereas the percentage liver growth was 85%, 105%, and 146%, respectively. Preoperative PT value (p = 0.01), RLL/total liver volume (TLV) ratio (p = 0.03), middle hepatic vein harvesting (p = 0.02), and postoperative peak TB (p < 0.01) were predictors of early functional recovery, whereas donor age (p = 0.03), RLL/TLV ratio (p = 0.004), and TLV/ body weight ratio (p = 0.02) predicted early volumetric recuperation. One-year post-RL donor hepatectomy, though functional recovery occurs in almost all (96%), donors had incomplete restoration (85%) of preoperative total liver volume. Modifiable predictors of regeneration could help in better and safer donor selection, while continuing to ensure successful recipient outcomes. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

Two-stage coal liquefaction without gas-phase hydrogen

DOEpatents

Stephens, H.P.

1986-06-05

A process is provided for the production of a hydrogen-donor solvent useful in the liquefaction of coal, wherein the water-gas shift reaction is used to produce hydrogen while simultaneously hydrogenating a donor solvent. A process for the liquefaction of coal using said solvent is also provided. The process enables avoiding the use of a separate water-gas shift reactor as well as high pressure equipment for liquefaction. 3 tabs.

Rotating-frame nuclear magnetic resonance study of the distinct dynamics of hydrogen donors in ZnO

NASA Astrophysics Data System (ADS)

Kue Park, Jun; Won Lee, Kyu; Eui Lee, Cheol

2013-07-01

The rotating-frame spin-lattice relaxation of two types of the hydrogen donors was well distinguished in the 1H nuclear magnetic resonance measurements in a sol-gel prepared ZnO system, providing a unique opportunity to study the distinct proton dynamics. Our study indicates interconversion of the interstitial H (Hi). The population of the mobile Hi showed decrease above ˜370 K, apparently being trapping into the oxygen vacancies resulting in the more stable oxygen-substitutional H (HO). The activation barrier for migration of Hi and the binding energy of HO were found to be 0.27 eV and 0.51 eV, respectively.

External electric field effect on the binding energy of a hydrogenic donor impurity in InGaAsP/InP concentric double quantum rings

NASA Astrophysics Data System (ADS)

Hu, Min; Wang, Hailong; Gong, Qian; Wang, Shumin

2018-04-01

Within the framework of effective-mass envelope-function theory, the ground state binding energy of a hydrogenic donor impurity is calculated in the InGaAsP/InP concentric double quantum rings (CDQRs) using the plane wave method. The effects of geometry, impurity position, external electric field and alloy composition on binding energy are considered. It is shown that the peak value of the binding energy appears in two rings with large gap as the donor impurity moves along the radial direction. The binding energy reaches the peak value at the center of ring height when the donor impurity moves along the axial direction. The binding energy shows nonlinear variation with the increase of ring height. With the external electric field applied along the z-axis, the binding energy of the donor impurity located at zi ≥ 0 decreases while that located at zi < 0 increases. In addition, the binding energy decreases with increasing Ga composition, but increases with the increasing As composition.

Anonymous or identity-registered sperm donors? A study of Dutch recipients' choices.

PubMed

Brewaeys, A; de Bruyn, J K; Louwe, L A; Helmerhorst, F M

2005-03-01

The aim of the present study was to gain insight into parents' own donor preferences within a system offering the choice between an anonymous and identity-registered donor. A comparison was made between recipients choosing for an anonymous donor (AD choosers) and those choosing for an identifiable donor (ID choosers) with regard to their sexual orientation, demographic characteristics, disclosure issues and infertility distress. Data from 105 couples (61% heterosexual, 39% lesbian) were registered on a standardized form during implication counselling sessions previous to treatment. Sixty-three per cent of the heterosexual couples and 98% of the lesbian couples had chosen an ID donor. Major differences between ID and AD choosers were identified. Among the ID choosers secrecy towards the child was no option, whereas 83% of the AD choosers did not intend to inform their child. Compared with heterosexual ID choosers, AD choosers were more distressed about their infertility and had a lower educational level. Legislation imposing ID donors appears to be acceptable for the majority of this study population. For a vulnerable group of heterosexual couples, who remained secretive about the use of a donor, adaptation to the new system is not self-evident.

Electron donor preference of a reductive dechlorinating consortium

USGS Publications Warehouse

Lorah, M.M.; Majcher, E.; Jones, E.; Driedger, G.; Dworatzek, S.; Graves, D.

2005-01-01

A wetland sediment-derived microbial consortium was developed by the USGS and propagated in vitro to large quantities by SiREM Laboratory for use in bioaugmentation applications. The consortium had the capacity to completely dechlorinate 1,1,2,2-tetrachloroethene, tetrachloroethylene, trichloroethylene, 1,1,2-trichloroethane, cis- and trans-1,2-dichoroethylene, 1.1-dichloroethylene, 1,2-dichloroethane, vinyl chloride, carbon tetrachloride and chloroform. A suite of electron donors with characteristics useful for bioaugmentation applications was tested. The electron donors included lactate (the donor used during WBC-2 development), ethanol, chitin (Chitorem???), hydrogen releasing compound (HRC???), emulsified vegetable oil (Newman Zone???), and hydrogen gas. Ethanol, lactate, and chitin were particularly effective with respect to stimulating, supporting, and sustaining reductive dechlorination of the broad suite of chemicals that WBC-2 biodegraded. Chitorem??? was the most effective "slow release" electron donor tested. This is an abstract of a paper presented at the Proceedings of the 8th International In Situ and On-Site Bioremediation Symposium (Baltimore, MD 6/6-9/2005).

Charged dopants in neutral supercells through substitutional donor (acceptor): nitrogen donor charging of the nitrogen-vacancy center in diamond

NASA Astrophysics Data System (ADS)

Löfgren, Robin; Pawar, Ravinder; Öberg, Sven; Larsson, J. Andreas

2018-02-01

Charged defects are traditionally computed by adding (subtracting) electrons for negative (positive) impurities. When using periodic boundary conditions this results in artificially charged supercells that also require a compensating background charge of the opposite sign, which makes slab supercells problematic because of an arbitrary dependence on the vacuum thickness. In this work, we test the method of using neutral supercells through the use of a substitutional electron donor (acceptor) to describe charged systems. We use density functional theory (DFT) to compare the effects of charging the well-studied NV-center in diamond by a substitutional donor nitrogen. We investigate the influence of the donor-N on the NV-center properties as a function of the distance between them, and find that they converge toward those obtained when adding an electron. We analyze the spin density and conclude that the donor-N has a zero magnetic moment, and thus, will not be seen in electron spin resonance. We validate our DFT energies through comparison to GW simulations. Charging the NV-center with a substitutional donor-N enables accurate calculations of slabs, without the ambiguity of using charged supercells. Implantation of donor-N atoms opens up the possibility to engineer NV-centers with the desired charge state for future ICT and sensor applications.

Hydrogen Fuel Capability Added to Combustor Flametube Rig

NASA Technical Reports Server (NTRS)

Frankenfield, Bruce J.

2003-01-01

Facility capabilities have been expanded at Test Cell 23, Research Combustor Lab (RCL23) at the NASA Glenn Research Center, with a new gaseous hydrogen fuel system. The purpose of this facility is to test a variety of fuel nozzle and flameholder hardware configurations for use in aircraft combustors. Previously, this facility only had jet fuel available to perform these various combustor flametube tests. The new hydrogen fuel system will support the testing and development of aircraft combustors with zero carbon dioxide (CO2) emissions. Research information generated from this test rig includes combustor emissions and performance data via gas sampling probes and emissions measuring equipment. The new gaseous hydrogen system is being supplied from a 70 000-standard-ft3 tube trailer at flow rates up to 0.05 lb/s (maximum). The hydrogen supply pressure is regulated, and the flow is controlled with a -in. remotely operated globe valve. Both a calibrated subsonic venturi and a coriolis mass flowmeter are used to measure flow. Safety concerns required the placement of all hydrogen connections within purge boxes, each of which contains a small nitrogen flow that is vented past a hydrogen detector. If any hydrogen leaks occur, the hydrogen detectors alert the operators and automatically safe the facility. Facility upgrades and modifications were also performed on other fluids systems, including the nitrogen gas, cooling water, and air systems. RCL23 can provide nonvitiated heated air to the research combustor, up to 350 psig at 1200 F and 3.0 lb/s. Significant modernization of the facility control systems and the data acquisition systems was completed. A flexible control architecture was installed that allows quick changes of research configurations. The labor-intensive hardware interface has been removed and changed to a software-based system. In addition, the operation of this facility has been greatly enhanced with new software programming and graphic operator interface

NAD(P)H-Independent Asymmetric C=C Bond Reduction Catalyzed by Ene Reductases by Using Artificial Co-substrates as the Hydrogen Donor

PubMed Central

Winkler, Christoph K; Clay, Dorina; Entner, Marcello; Plank, Markus; Faber, Kurt

2014-01-01

To develop a nicotinamide-independent single flavoenzyme system for the asymmetric bioreduction of C=C bonds, four types of hydrogen donor, encompassing more than 50 candidates, were investigated. Six highly potent, cheap, and commercially available co-substrates were identified that (under the optimized conditions) resulted in conversions and enantioselectivities comparable with, or even superior to, those obtained with traditional two-enzyme nicotinamide adenine dinucleotide phosphate (NAD(P)H)-recycling systems. PMID:24382795

A brown dwarf mass donor in an accreting binary.

PubMed

Littlefair, S P; Dhillon, V S; Marsh, T R; Gänsicke, Boris T; Southworth, John; Watson, C A

2006-12-08

A long-standing and unverified prediction of binary star evolution theory is the existence of a population of white dwarfs accreting from substellar donor stars. Such systems ought to be common, but the difficulty of finding them, combined with the challenge of detecting the donor against the light from accretion, means that no donor star to date has a measured mass below the hydrogen burning limit. We applied a technique that allowed us to reliably measure the mass of the unseen donor star in eclipsing systems. We were able to identify a brown dwarf donor star, with a mass of 0.052 +/- 0.002 solar mass. The relatively high mass of the donor star for its orbital period suggests that current evolutionary models may underestimate the radii of brown dwarfs.

Hydrogen peroxide kinetics in water radiolysis

NASA Astrophysics Data System (ADS)

Iwamatsu, Kazuhiro; Sundin, Sara; LaVerne, Jay A.

2018-04-01

The kinetics of the formation and reaction of hydrogen peroxide in the long time γ- radiolysis of water is examined using a combination of experiment with model calculations. Escape yields of hydrogen peroxide on the microsecond time scale are easily measured with added radical scavengers even with substantial amounts of initial added hydrogen peroxide. The γ-radiolysis of aqueous hydrogen peroxide solutions without added radical scavengers reach a steady state limiting concentration of hydrogen peroxide with increasing dose, and that limit is directly proportional to the initial concentration of added hydrogen peroxide. The dose necessary to reach that limiting hydrogen peroxide concentration is also proportional to the initial concentration, but dose rate has a very small effect. The addition of molecular hydrogen to aqueous solutions of hydrogen peroxide leads to a decrease in the high dose limiting hydrogen peroxide concentration that is linear with the initial hydrogen concentration, but the amount of decrease is not stoichiometric. Proton irradiations of solutions with added hydrogen peroxide and hydrogen are more difficult to predict because of the decreased yields of radicals; however, with a substantial increase in dose rate there is a sufficient decrease in radical yields that hydrogen addition has little effect on hydrogen peroxide decay.

Development of a Hydrogen Uptake-Release Mg-Based Alloy by Adding a Polymer CMC (Carboxymethylcellulose, Sodium Salt) via Reaction-Accompanying Milling

NASA Astrophysics Data System (ADS)

Kwak, Young Jun; Choi, Eunho; Song, Myoung Youp

2018-03-01

The addition of carboxymethylcellulose, sodium salt (CMC) might improve the hydrogen uptake and release properties of Mg since it has a relatively low melting point and the melting of CMC during milling in hydrogen (reaction-accompanying milling) may make the milled samples be in good states to absorb and release hydrogen rapidly and to have a large hydrogen-storage capacity. Samples with compositions of 95 w/o Mg + 5 w/o CMC (named Mg-5CMC) and 90 w/o Mg + 10 w/o CMC (named Mg-10CMC) were prepared by adding CMC via reaction-accompanying milling. Activation of Mg-10CMC was completed after about 3 hydrogen uptake-release cycles. Mg-10CMC had a higher initial hydrogen uptake rate and a larger amount of hydrogen absorbed in 60 min, U (60 min), than Mg-5CMC before and after activation. At the cycle number of three (CN = 3), Mg-10CMC had a very high initial hydrogen uptake rate (1.56 w/o H/min) and a large U (60 min) (5.57 w/o H) at 593 K in hydrogen of 12 bar, showing that the activated Mg-10CMC has an effective hydrogen-storage capacity of about 5.6 w/o at 593 K in hydrogen of 12 bar at CN = 3. At CN = 2, Mg-10CMC released 1.00 w/o H in 2.5 min, 4.67 w/o H in 10 min, and 4.76 w/o H in 60 min at 648 K in hydrogen of 1.0 bar. The milling in hydrogen of Mg with CMC is believed to generate imperfections and cracks and reduce the particle size. The addition of 10 w/o CMC was more effective on the initial hydrogen uptake rate and U (60 min) compared with the 10 w/o additions of NbF5, TaF5, Fe2O3, and MnO, and the 10 w/o simultaneous addition of Ni, Fe, and Ti. To the best of our knowledge, this study is the first in which a polymer CMC is added to Mg by reaction-accompanying milling to improve the hydrogen storage properties of Mg.

Hydrogen bonding. Part 25. The nature of the hydrogen bond in hydroxytropenylium chloride (tropone hydrochloride)

NASA Astrophysics Data System (ADS)

Harmon, Kenneth M.; Cross, Joan E.; Toccalino, Patricia L.

1988-08-01

Hydroxytropenylium iodide and bromide contain normal electrostatic OH⋯X - hydrogen bonds. Hydroxytropenylium chloride, however, contains a hydrogen bond intermediate between the normal electrostatic type and the very strong covalent type, similar to the hydrogen bonds found in choline fluoride or the Type I C∞v hydrogen dihalide ions. Infrared comparisons with compounds previously studied demonstrate that the hydroxytropenylium ion is a stronger hydrogen bond donor than either choline cation or protonated betaine cation, and suggest that hydroxytropenylium fluoride, if it can be prepared, should contain a three-center covalent hydrogen bond.

Mechanism of Pd(NHC)-catalyzed transfer hydrogenation of alkynes.

PubMed

Hauwert, Peter; Boerleider, Romilda; Warsink, Stefan; Weigand, Jan J; Elsevier, Cornelis J

2010-12-01

The transfer semihydrogenation of alkynes to (Z)-alkenes shows excellent chemo- and stereoselectivity when using a zerovalent palladium(NHC)(maleic anhydride)-complex as precatalyst and triethylammonium formate as hydrogen donor. Studies on the kinetics under reaction conditions showed a broken positive order in substrate and first order in catalyst and hydrogen donor. Deuterium-labeling studies on the hydrogen donor showed that both hydrogens of formic acid display a primary kinetic isotope effect, indicating that proton and hydride transfers are separate rate-determining steps. By monitoring the reaction with NMR, we observed the presence of a coordinated formate anion and found that part of the maleic anhydride remains coordinated during the reaction. From these observations, we propose a mechanism in which hydrogen transfer from coordinated formate anion to zerovalent palladium(NHC)(MA)(alkyne)-complex is followed by migratory insertion of hydride, after which the product alkene is liberated by proton transfer from the triethylammonium cation. The explanation for the high selectivity observed lies in the competition between strongly coordinating solvent and alkyne for a Pd(alkene)-intermediate.

Use of the donor lung after asphyxiation or drowning: effect on lung transplant recipients.

PubMed

Whitson, Bryan A; Hertz, Marshall I; Kelly, Rosemary F; Higgins, Robert S D; Kilic, Ahmet; Shumway, Sara J; D'Cunha, Jonathan

2014-10-01

With the relative paucity of acceptable donors for lung transplantation, criteria for extended donor consideration are being explored. We sought to evaluate the suitability of donors whose cause of death was asphyxiation or drowning (A/D) as a potential option to enlarge the donor pool. We queried the United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research registry for lung transplantation from 1987 to 2010 to assess associations between cause of death and recipient survival using the Kaplan-Meier method. To adjust for potential confounders, we used a Cox proportional hazards model and a logistic regression model to evaluate incidence of rejection within the first year. There were 18,250 adult primary lung transplantations performed, with 309 A/D donors. There was no difference in survival between groups (log-rank, p = 0.52). There were no differences in demographics, length of stay, airway dehiscence, lung allocation score (LAS), or ischemic time in univariate analysis (all p > 0.05). The A/D lung recipients had fewer deaths from pulmonary causes (5.8% versus 9.5%; p = 0.02). Proportional hazards analysis was significant for double lung transplantation (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.8-0.9), height difference (HR, 1.002; 95% CI, 1.00-1.003), donor age greater than 50 years (HR, 0.89; 95% CI, 0.83-0.96), and recipient age greater than 55 years (HR, 0.8; 95% CI, 0.76-0.84). A/D cause of death did not impact survival in multivariate analysis. A/D as a donor cause of death was not associated with poor long-term survival or incidence of rejection in the first year after transplantation. Donor cause of death by A/D, when carefully evaluated and selected, should not automatically exclude the organ from transplant consideration. These results provide important justification for potentially broadening the donor pool safely. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights

Alternative Donor/Unrelated Donor Transplants for the β-Thalassemia and Sickle Cell Disease.

PubMed

Fitzhugh, Courtney D; Abraham, Allistair; Hsieh, Matthew M

2017-01-01

Considerable progress with respect to donor source has been achieved in allogeneic stem cell transplant for patients with hemoglobin disorders, with matched sibling donors in the 1980s, matched unrelated donors and cord blood sources in the 1990s, and haploidentical donors in the 2000s. Many studies have solidified hematopoietic progenitors from matched sibling marrow, cord blood, or mobilized peripheral blood as the best source-with the lowest graft rejection and graft versus host disease (GvHD), and highest disease-free survival rates. For patients without HLA-matched sibling donors, but who are otherwise eligible for transplant, fully allelic matched unrelated donor (8/8 HLA-A, B, C, DRB1) appears to be the next best option, though an ongoing study in patients with sickle cell disease will provide data that are currently lacking. There are high GvHD rates and low engraftment rates in some of the unrelated cord transplant studies. Haploidentical donors have emerged in the last decade to have less GvHD; however, improvements are needed to increase the engraftment rate. Thus the decision to use unrelated cord blood units or haploidentical donors may depend on the institutional expertise; there is no clear preferred choice over the other. Active research is ongoing in expanding cord blood progenitor cells to overcome the limitation of cell dose, including the options of small molecule inhibitor compounds added to ex vivo culture or co-culture with supportive cell lines. There are inconsistent data from using 7/8 or lower matched unrelated donors. Before routine use of these less matched donor sources, work is needed to improve patient selection, conditioning regimen, GvHD prophylaxis, and/or other strategies.

The hydrolysis of epoxides catalyzed by inorganic ammonium salts in water: kinetic evidence for hydrogen bond catalysis.

PubMed

Nozière, B; Fache, F; Maxut, A; Fenet, B; Baudouin, A; Fine, L; Ferronato, C

2018-01-17

Naturally-occurring inorganic ammonium ions have been recently reported as efficient catalysts for some organic reactions in water, which contributes to the understanding of the chemistry in some natural environments (soils, seawater, atmospheric aerosols, …) and biological systems, and is also potentially interesting for green chemistry as many of their salts are cheap and non-toxic. In this work, the effect of NH 4 + ions on the hydrolysis of small epoxides in water was studied kinetically. The presence of NH 4 + increased the hydrolysis rate by a factor of 6 to 25 compared to pure water and these catalytic effects were shown not to result from other ions, counter-ions or from acid or base catalysis, general or specific. The small amounts of amino alcohols produced in the reactions were identified as the actual catalysts by obtaining a strong acceleration of the reactions when adding these compounds directly to the epoxides in water. Replacing the amino alcohols by other strong hydrogen-bond donors, such as trifluoroethanol (TFE) or hexafluoroisopropanol (HFIP) gave the same results, demonstrating that the kinetics of these reactions was driven by hydrogen-bond catalysis. Because of the presence of many hydrogen-bond donors in natural environments (for instance amines and hydroxy-containing compounds), hydrogen-bond catalysis is likely to contribute to many reaction rates in these environments.

Searching for magnetism in hydrogenated graphene: using highly hydrogenated graphene prepared via Birch reduction of graphite oxides.

PubMed

Eng, Alex Yong Sheng; Poh, Hwee Ling; Šaněk, Filip; Maryško, Miroslav; Matějková, Stanislava; Sofer, Zdeněk; Pumera, Martin

2013-07-23

Fully hydrogenated graphene (graphane) and partially hydrogenated graphene materials are expected to possess various fundamentally different properties from graphene. We have prepared highly hydrogenated graphene containing 5% wt of hydrogen via Birch reduction of graphite oxide using elemental sodium in liquid NH3 as electron donor and methanol as proton donor in the reduction. We also investigate the influence of preparation method of graphite oxide, such as the Staudenmaier, Hofmann or Hummers methods on the hydrogenation rate. A control experiment involving NaNH2 instead of elemental Na was also performed. The materials were characterized in detail by electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy both at room and low temperatures, X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, combustible elemental analysis and electrical resistivity measurements. Magnetic measurements are provided of bulk quantities of highly hydrogenated graphene. In the whole temperature range up to room temperature, the hydrogenated graphene exhibits a weak ferromagnetism in addition to a contribution proportional to field that is caused not only by diamagnetism but also likely by an antiferromagnetic influence. The origin of the magnetism is also determined to arise from the hydrogenated graphene itself, and not as a result of any metallic impurities.

Tetraalkylammonium Salts as Hydrogen-Bonding Catalysts.

PubMed

Shirakawa, Seiji; Liu, Shiyao; Kaneko, Shiho; Kumatabara, Yusuke; Fukuda, Airi; Omagari, Yumi; Maruoka, Keiji

2015-12-21

Although the hydrogen-bonding ability of the α hydrogen atoms on tetraalkylammonium salts is often discussed with respect to phase-transfer catalysts, catalysis that utilizes the hydrogen-bond-donor properties of tetraalkylammonium salts remains unknown. Herein, we demonstrate hydrogen-bonding catalysis with newly designed tetraalkylammonium salt catalysts in Mannich-type reactions. The structure and the hydrogen-bonding ability of the new ammonium salts were investigated by X-ray diffraction analysis and NMR titration studies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of hydrogen bonding on partition coefficients

NASA Astrophysics Data System (ADS)

Borges, Nádia Melo; Kenny, Peter W.; Montanari, Carlos A.; Prokopczyk, Igor M.; Ribeiro, Jean F. R.; Rocha, Josmar R.; Sartori, Geraldo Rodrigues

2017-02-01

This Perspective explores how consideration of hydrogen bonding can be used to both predict and better understand partition coefficients. It is shown how polarity of both compounds and substructures can be estimated from measured alkane/water partition coefficients. When polarity is defined in this manner, hydrogen bond donors are typically less polar than hydrogen bond acceptors. Analysis of alkane/water partition coefficients in conjunction with molecular electrostatic potential calculations suggests that aromatic chloro substituents may be less lipophilic than is generally believed and that some of the effect of chloro-substitution stems from making the aromatic π-cloud less available to hydrogen bond donors. Relationships between polarity and calculated hydrogen bond basicity are derived for aromatic nitrogen and carbonyl oxygen. Aligned hydrogen bond acceptors appear to present special challenges for prediction of alkane/water partition coefficients and this may reflect `frustration' of solvation resulting from overlapping hydration spheres. It is also shown how calculated hydrogen bond basicity can be used to model the effect of aromatic aza-substitution on octanol/water partition coefficients.

Gas diffusion electrodes improve hydrogen gas mass transfer for a hydrogen oxidizing bioanode

PubMed Central

Rodenas, Pau; Zhu, Fangqi; Sleutels, Tom; Saakes, Michel; Buisman, Cees

2017-01-01

Abstract Background Bioelectrochemical systems (BESs) are capable of recovery of metals at a cathode through oxidation of organic substrate at an anode. Recently, also hydrogen gas was used as an electron donor for recovery of copper in BESs. Oxidation of hydrogen gas produced a current density of 0.8 A m‐2 and combined with Cu2+ reduction at the cathode, produced 0.25 W m‐2. The main factor limiting current production was the mass transfer of hydrogen to the biofilm due to the low solubility of hydrogen in the anolyte. Here, the mass transfer of hydrogen gas to the bioanode was improved by use of a gas diffusion electrode (GDE). Results With the GDE, hydrogen was oxidized to produce a current density of 2.9 A m‐2 at an anode potential of –0.2 V. Addition of bicarbonate to the influent led to production of acetate, in addition to current. At a bicarbonate concentration of 50 mmol L‐1, current density increased to 10.7 A m‐2 at an anode potential of –0.2 V. This increase in current density could be due to oxidation of formed acetate in addition to oxidation of hydrogen, or enhanced growth of hydrogen oxidizing bacteria due to the availability of acetate as carbon source. The effect of mass transfer was further assessed through enhanced mixing and in combination with the addition of bicarbonate (50 mmol L‐1) current density increased further to 17.1 A m‐2. Conclusion Hydrogen gas may offer opportunities as electron donor for bioanodes, with acetate as potential intermediate, at locations where excess hydrogen and no organics are available. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:29200586

Hydrogen Donor-Acceptor Fluctuations from Kinetic Isotope Effects: A Phenomenological Model

PubMed Central

Roston, Daniel; Cheatum, Christopher M.; Kohen, Amnon

2012-01-01

Kinetic isotope effects (KIEs) and their temperature dependence can probe the structural and dynamic nature of enzyme-catalyzed proton or hydride transfers. The molecular interpretation of their temperature dependence requires expensive and specialized QM/MM calculations to provide a quantitative molecular understanding. Currently available phenomenological models use a non-adiabatic assumption that is not appropriate for most hydride and proton-transfer reactions, while others require more parameters than the experimental data justify. Here we propose a phenomenological interpretation of KIEs based on a simple method to quantitatively link the size and temperature dependence of KIEs to a conformational distribution of the catalyzed reaction. The present model assumes adiabatic hydrogen tunneling, and by fitting experimental KIE data, the model yields a population distribution for fluctuations of the distance between donor and acceptor atoms. Fits to data from a variety of proton and hydride transfers catalyzed by enzymes and their mutants, as well as non-enzymatic reactions, reveal that steeply temperature-dependent KIEs indicate the presence of at least two distinct conformational populations, each with different kinetic behaviors. We present the results of these calculations for several published cases and discuss how the predictions of the calculations might be experimentally tested. The current analysis does not replace molecular quantum mechanics/molecular mechanics (QM/MM) investigations, but it provides a fast and accessible way to quantitatively interpret KIEs in the context of a Marcus-like model. PMID:22857146

Accelerating Quinoline Biodegradation and Oxidation with Endogenous Electron Donors.

PubMed

Bai, Qi; Yang, Lihui; Li, Rongjie; Chen, Bin; Zhang, Lili; Zhang, Yongming; Rittmann, Bruce E

2015-10-06

Quinoline, a recalcitrant heterocyclic compound, is biodegraded by a series of reactions that begin with mono-oxygenations, which require an intracellular electron donor. Photolysis of quinoline can generate readily biodegradable products, such as oxalate, whose bio-oxidation can generate endogenous electron donors that ought to accelerate quinoline biodegradation and, ultimately, mineralization. To test this hypothesis, we compared three protocols for the biodegradation of quinoline: direct biodegradation (B), biodegradation after photolysis of 1 h (P1h+B) or 2 h (P2h+B), and biodegradation by adding oxalate commensurate to the amount generated from photolysis of 1 h (O1+B) or 2 h (O2+B). The experimental results show that P1h+B and P2h+B accelerated quinoline biodegradation by 19% and 50%, respectively, compared to B. Protocols O1+B and O2+B also gave 19% and 50% increases, respectively. During quinoline biodegradation, its first intermediate, 2-hydroxyquinoline, accumulated gradually in parallel to quinoline loss but declined once quinoline was depleted. Mono-oxygenation of 2-hydroxyquinoline competed with mono-oxygenation of quinoline, but the inhibition was relieved when extra electrons donors were added from oxalate, whether formed by UV photolysis or added exogenously. Rapid oxalate oxidation stimulated both mono-oxygenations, which accelerated the overall quinoline oxidation that provided the bulk of the electron donor.

Electrochemical hydrogenation of a homogeneous nickel complex to form a surface adsorbed hydrogen-evolving species

DOE PAGES

Martin, Daniel J.; McCarthy, Brian D.; Donley, Carrie L.; ...

2014-12-04

Here, a Ni(ii) complex with nitrogen and sulfur donor ligands degrades electrochemically in the presence of acid in acetonitrile to form an electrode adsorbed film that catalytically evolves hydrogen.

Donor defects and small polarons on the TiO2(110) surface

NASA Astrophysics Data System (ADS)

Moses, P. G.; Janotti, A.; Franchini, C.; Kresse, G.; Van de Walle, C. G.

2016-05-01

The role of defects in the chemical activity of the rutile TiO2(110) surface remains a rich topic of research, despite the rutile (110) being one of the most studied surfaces of transition-metal oxides. Here, we present results from hybrid functional calculations that reconcile apparently disparate views on the impact of donor defects, such as oxygen vacancies and hydrogen impurities, on the electronic structure of the (110) rutile surface. We find that the bridging oxygen vacancy and adsorbed or substitutional hydrogen are actually shallow donors, which do not induce gap states. The excess electrons from these donor centers tend to localize in the form of small polarons, which are the factual cause of the deep states ˜1 eV below the conduction band, often observed in photoelectron spectroscopy measurements. Our results offer a new framework for understanding the surface electronic structure of TiO2 and related oxides.

Hydrogen-related excitons and their excited-state transitions in ZnO

NASA Astrophysics Data System (ADS)

Heinhold, R.; Neiman, A.; Kennedy, J. V.; Markwitz, A.; Reeves, R. J.; Allen, M. W.

2017-02-01

The role of hydrogen in the photoluminescence (PL) of ZnO was investigated using four different types of bulk ZnO single crystal, with varying concentrations of unintentional hydrogen donor and Group I acceptor impurities. Photoluminescence spectra were measured at 3 K, with emission energies determined to ±50 μeV, before and after separate annealing in O2, N2, and H2 atmospheres. Using this approach, several new hydrogen-related neutral-donor-bound excitons, and their corresponding B exciton, ionized donor, and two electron satellite (TES) excited state transitions were identified and their properties further investigated using hydrogen and deuterium ion implantation. The commonly observed I4 (3.36272 eV) emission due to excitons bound to multicoordinated hydrogen inside an oxygen vacancy (HO), that is present in most ZnO material, was noticeably absent in hydrothermally grown (HT) ZnO and instead was replaced by a doublet of two closely lying recombination lines I4 b ,c (3.36219, 3.36237 eV) due to a hydrogen-related donor with a binding energy (ED) of 47.7 meV. A new and usually dominant recombination line I6 -H (3.36085 eV) due to a different hydrogen-related defect complex with an ED of 49.5 meV was also identified in HT ZnO. Here, I4 b ,c and I6 -H were stable up to approximately 400 and 600 °C, respectively, indicating that they are likely to contribute to the unintentional n -type conductivity of ZnO. Another doublet I5 (3.36137, 3.36148 eV) was identified in hydrogenated HT ZnO single crystals with low Li concentrations, and this was associated with a defect complex with an ED of 49.1 meV. A broad near band edge (NBE) emission centered at 3.366 eV was associated with excitons bound to subsurface hydrogen. We further demonstrate that hydrogen incorporates on different lattice sites for different annealing conditions and show that the new features I4 b ,c, I6 -H, and I5 most likely originate from the lithium-hydrogen defect complexes L iZn-HO , A l

Haemostatic effects of adrenaline-lidocaine subcutaneous infiltration at donor sites.

PubMed

Gacto, P; Miralles, F; Pereyra, J J; Perez, A; Martínez, E

2009-05-01

This study sought methods in burn surgery to reduce postoperative pain and blood loss at donor sites. A prospective, randomised, controlled, blinded trial included 56 people undergoing burn surgery, divided into two groups. Both groups received subcutaneous infiltration at donor sites, with either 1:500,000 adrenaline solution containing added lidocaine or with 0.45% normal saline (controls). Outcome measurements included amount of intraoperative bleeding, need for electrocautery, days the hydrocolloid dressing remained on donor sites, percentage of re-epithelialised skin at donor sites 1 week after surgery and viability of skin grafts. Results indicated that subcutaneous adrenaline-lidocaine infiltration at donor sites reduced intraoperative bleeding, decreased postoperative pain, shortened the duration of surgery and general anaesthesia and accelerated re-epithelialisation at the donor site. The overall graft take in both groups was similar.

Donor cycle and donor segmentation: new tools for improving blood donor management.

PubMed

Veldhuizen, I; Folléa, G; de Kort, W

2013-07-01

An adequate donor population is of key importance for the entire blood transfusion chain. For good donor management, a detailed overview of the donor database is therefore imperative. This study offers a new description of the donor cycle related to the donor management process. It also presents the outcomes of a European Project, Donor Management IN Europe (DOMAINE), regarding the segmentation of the donor population into donor types. Blood establishments (BEs) from 18 European countries, the Thalassaemia International Federation and a representative from the South-Eastern Europe Health Network joined forces in DOMAINE. A questionnaire assessed blood donor management practices and the composition of the donor population using the newly proposed DOMAINE donor segmentation. 48 BEs in 34 European countries were invited to participate. The response rate was high (88%). However, only 14 BEs could deliver data on the composition of their donor population. The data showed large variations and major imbalances in the donor population. In 79% of the countries, inactive donors formed the dominant donor type. Only in 21%, regular donors were the largest subgroup, and in 29%, the proportion of first-time donors was higher than the proportion of regular donors. Good donor management depends on a thorough insight into the flow of donors through their donor career. Segmentation of the donor database is an essential tool to understand the influx and efflux of donors. The DOMAINE donor segmentation helps BEs in understanding their donor database and to adapt their donor recruitment and retention practices accordingly. Ways to use this new tool are proposed. © 2013 International Society of Blood Transfusion.

NMR experiments for the rapid identification of P=O···H-X type hydrogen bonds in nucleic acids.

PubMed

Duchardt-Ferner, Elke; Wöhnert, Jens

2017-10-01

Hydrogen bonds involving the backbone phosphate groups occur with high frequency in functional RNA molecules. They are often found in well-characterized tertiary structural motifs presenting powerful probes for the rapid identification of these motifs for structure elucidation purposes. We have shown recently that stable hydrogen bonds to the phosphate backbone can in principle be detected by relatively simple NMR-experiments, providing the identity of both the donor hydrogen and the acceptor phosphorous within the same experiment (Duchardt-Ferner et al., Angew Chem Int Ed Engl 50:7927-7930, 2011). However, for imino and hydroxyl hydrogen bond donor groups rapidly exchanging with the solvent as well as amino groups broadened by conformational exchange experimental sensitivity is severely hampered by extensive line broadening. Here, we present improved methods for the rapid identification of hydrogen bonds to phosphate groups in nucleic acids by NMR. The introduction of the SOFAST technique into 1 H, 31 P-correlation experiments as well as a BEST-HNP experiment exploiting 3h J N,P rather than 2h J H,P coupling constants enables the rapid and sensitive identification of these hydrogen bonds in RNA. The experiments are applicable for larger RNAs (up to ~ 100-nt), for donor groups influenced by conformational exchange processes such as amino groups and for hydrogen bonds with rather labile hydrogens such as 2'-OH groups as well as for moderate sample concentrations. Interestingly, the size of the through-hydrogen bond scalar coupling constants depends not only on the type of the donor group but also on the structural context. The largest coupling constants were measured for hydrogen bonds involving the imino groups of protonated cytosine nucleotides as donors.

Donor defects and small polarons on the TiO{sub 2}(110) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moses, P. G.; Janotti, A., E-mail: janotti@udel.edu; Van de Walle, C. G.

2016-05-14

The role of defects in the chemical activity of the rutile TiO{sub 2}(110) surface remains a rich topic of research, despite the rutile (110) being one of the most studied surfaces of transition-metal oxides. Here, we present results from hybrid functional calculations that reconcile apparently disparate views on the impact of donor defects, such as oxygen vacancies and hydrogen impurities, on the electronic structure of the (110) rutile surface. We find that the bridging oxygen vacancy and adsorbed or substitutional hydrogen are actually shallow donors, which do not induce gap states. The excess electrons from these donor centers tend tomore » localize in the form of small polarons, which are the factual cause of the deep states ∼1 eV below the conduction band, often observed in photoelectron spectroscopy measurements. Our results offer a new framework for understanding the surface electronic structure of TiO{sub 2} and related oxides.« less

Microbial Analysis of Donor Corneoscleral Rims and Storage Media.

PubMed

Tsui, Edmund; Luong, Preston M; Fogel, Jessa; Fogel, Erin S; Zegans, Michael E

2018-05-03

We aim to investigate bacterial and fungal cultures of hypothermic donor corneal storage media (Optisol-GS) and donor rims. All corneal transplants performed from January 1, 2015 to June 30, 2016 by a single surgeon at a single facility were retrospectively reviewed. Aerobic, anaerobic, and fungal cultures were routinely obtained from all donor rims and cornea storage media. Culture results and clinical courses were recorded. Eighty-four corneal transplants were performed. Five of 84 grafts (5.95%) had positive bacteria donor rim cultures. Fungal donor rim cultures were positive in 5/84 grafts (5.95%) of which two grew Candida spp. Storage media bacterial cultures were positive in 2/84 (2.4%) cultures. Storage media fungal cultures were positive in 1/84 (1.2%) cultures. No patients developed any evidence of clinical infection. Given the increasing rates of postkeratoplasty fungal infections, the identification of positive fungal cultures from donor rims and storage media warrants further evaluation of adding antifungals to storage media.

HYDROGEN CONCENTRATIONS IN SULFATE-REDUCING ESTUARINE SEDIMENTS DURING PCE DEHALOGENATION

EPA Science Inventory

Despite recent progress made evaluating the role of hydrogen (H2) as a key electron donor in the anaerobic remediation of chloroethenes, few studies have focused on the evaluation of hydrogen thresholds relative to reductive dehalogenation in sulfidogenic environments. Competitio...

Hydrogen sulfide donors alleviate itch secondary to the activation of type-2 protease activated receptors (PAR-2) in mice.

PubMed

Coavoy-Sánchez, S A; Rodrigues, L; Teixeira, S A; Soares, A G; Torregrossa, R; Wood, M E; Whiteman, M; Costa, S K P; Muscará, M N

2016-11-01

Hydrogen sulfide (H 2 S) has been highlighted as an endogenous signaling molecule and we have previously found that it can inhibit histamine-mediated itching. Pruritus is the most common symptom of cutaneous diseases and anti-histamines are the usual treatment; however, anti-histamine-resistant pruritus is common in some clinical settings. In this way, the involvement of mediators other than histamine in the context of pruritus requires new therapeutic targets. Considering that the activation of proteinase-activated receptor 2 (PAR-2) is involved in pruritus both in rodents and humans, in this study we investigated the effect of H 2 S donors on the acute scratching behavior mediated by PAR-2 activation in mice, as well as some of the possible pharmacological mechanisms involved. The intradermal injection of the PAR-2 peptide agonist SLIGRL-NH 2 (8-80nmol) caused a dose-dependent scratching that was unaffected by intraperitoneal pre-treatment with the histamine H1 antagonist pyrilamine (30mg/kg). Co-injection of SLIGRL-NH 2 (40nmol) with either the slow-release H 2 S donor GYY4137 (1 and 3nmol) or the spontaneous donor NaHS (1 and 0.3nmol) significantly reduced pruritus. Co-treatment with the K ATP channel blocker glibenclamide (200nmol) or the nitric oxide (NO) donor sodium nitroprusside (10nmol) abolished the antipruritic effects of NaHS; however, the specific soluble guanylyl cyclase inhibitor ODQ (30μg) had no significant effects. The transient receptor potential ankyrin type 1 (TRPA1) antagonist HC-030031 (20μg) significantly reduced SLIGRL-NH 2 -induced pruritus; however pruritus induced by the TRPA1 agonist AITC (1000nmol) was unaffected by NaHS. Based on these data, we conclude that pruritus secondary to PAR-2 activation can be reduced by H 2 S, which acts through K ATP channel opening and involves NO in a cyclic guanosine monophosphate (cGMP)-independent manner. Furthermore, TRPA1 receptors mediate the pruritus induced by activation of PAR-2, but H 2 S

Effects of hydrogen on acceptor activation in ternary nitride semiconductors

DOE PAGES

Fioretti, Angela N.; Stokes, Adam; Young, Matthew R.; ...

2017-02-09

Doping control is necessary to unlock the scientific and technological potential of many materials, including ternary II-IV-nitride semiconductors, which are closely related to binary GaN. In particular, ZnSnN 2 has been reported to have degenerate doping density, despite bandgap energies that are well suited for solar energy conversion. Here, we show that annealing Zn-rich Zn 1+xSn 1-xN 2 grown with added hydrogen reduces its free electron density by orders of magnitude, down to 4 x 10 16 cm -3. This experimental observation can be explained by hydrogen passivation of acceptors in Zn 1+xSn 1-xN 2 during growth, lowering the drivingmore » force for unintentional donor formation. Lastly, these results indicate that the doping control principles used in GaN can be translated to ZnSnN 2, suggesting that other strategies used in binary III-Vs can be applied to accelerate the technological development of ternary II-IV-N 2 materials.« less

Optimizing donor scheduling before recruitment: An effective approach to increasing apheresis platelet collections.

PubMed

Lokhandwala, Parvez M; Shike, Hiroko; Wang, Ming; Domen, Ronald E; George, Melissa R

2018-01-01

Typical approach for increasing apheresis platelet collections is to recruit new donors. Here, we investigated the effectiveness of an alternative strategy: optimizing donor scheduling, prior to recruitment, at a hospital-based blood donor center. Analysis of collections, during the 89 consecutive months since opening of donor center, was performed. Linear regression and segmented time-series analyses were performed to calculate growth rates of collections and to test for statistical differences, respectively. Pre-intervention donor scheduling capacity was 39/month. In the absence of active donor recruitment, during the first 29 months, the number of collections rose gradually to 24/month (growth-rate of 0.70/month). However, between month-30 and -55, collections exhibited a plateau at 25.6 ± 3.0 (growth-rate of -0.09/month) (p<0.0001). This plateau-phase coincided with donor schedule approaching saturation (65.6 ± 7.6% schedule booked). Scheduling capacity was increased by following two interventions: adding an apheresis instrument (month-56) and adding two more collection days/week (month-72). Consequently, the scheduling capacity increased to 130/month. Post-interventions, apheresis platelet collections between month-56 and -81 exhibited a spontaneous renewed growth at a rate of 0.62/month (p<0.0001), in absence of active donor recruitment. Active donor recruitment in month-82 and -86, when the donor schedule had been optimized to accommodate further growth, resulted in a dramatic but transient surge in collections. Apheresis platelet collections plateau at nearly 2/3rd of the scheduling capacity. Optimizing the scheduling capacity prior to active donor recruitment is an effective strategy to increase platelet collections at a hospital-based donor center.

Quantum confinement of a hydrogenic donor in a double quantum well: Through diamagnetic susceptibility

NASA Astrophysics Data System (ADS)

Vignesh, G.; Nithiananthi, P.

2015-06-01

Diamagnetic susceptibility of a randomly distributed donor in a GaAs/Al0.3Ga0.7As Double Quantum Well has been calculated in its ground state as a function of barrier and well width. It is shown that the modification in the barrier and well dimension significantly influences the dimensional character of the donor through modulating the subband distribution and in turn the localization of the donor. The effect of barrier and well thickness on the interparticle distance has also been observed. Interestingly it opens up the possibility of tuning the susceptibility and monitoring the tunnel coupling among the wells.

An AAA-DDD triply hydrogen-bonded complex easily accessible for supramolecular polymers.

PubMed

Han, Yi-Fei; Chen, Wen-Qiang; Wang, Hong-Bo; Yuan, Ying-Xue; Wu, Na-Na; Song, Xiang-Zhi; Yang, Lan

2014-12-15

For a complementary hydrogen-bonded complex, when every hydrogen-bond acceptor is on one side and every hydrogen-bond donor is on the other, all secondary interactions are attractive and the complex is highly stable. AAA-DDD (A=acceptor, D=donor) is considered to be the most stable among triply hydrogen-bonded sequences. The easily synthesized and further derivatized AAA-DDD system is very desirable for hydrogen-bonded functional materials. In this case, AAA and DDD, starting from 4-methoxybenzaldehyde, were synthesized with the Hantzsch pyridine synthesis and Friedländer annulation reaction. The association constant determined by fluorescence titration in chloroform at room temperature is 2.09×10(7)  M(-1) . The AAA and DDD components are not coplanar, but form a V shape in the solid state. Supramolecular polymers based on AAA-DDD triply hydrogen bonded have also been developed. This work may make AAA-DDD triply hydrogen-bonded sequences easily accessible for stimuli-responsive materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nano-ferrites for Water Splitting: Unprecedented High Photocatalytic Hydrogen Production under Visible Light

EPA Science Inventory

In the present investigation, hydrogen production via water splitting by nano ferrites has been studied using ethanol as the sacrificial donor. The nano ferrite has shown great potential in hydrogen generation with hydrogen yield of 8275 9moles/h/ g of photocatalyst under visible...

Quantum confinement of a hydrogenic donor in a double quantum well: Through diamagnetic susceptibility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vignesh, G.; Nithiananthi, P., E-mail: nithyauniq@gmail.com

2015-06-24

Diamagnetic susceptibility of a randomly distributed donor in a GaAs/Al{sub 0.3}Ga{sub 0.7}As Double Quantum Well has been calculated in its ground state as a function of barrier and well width. It is shown that the modification in the barrier and well dimension significantly influences the dimensional character of the donor through modulating the subband distribution and in turn the localization of the donor. The effect of barrier and well thickness on the interparticle distance has also been observed. Interestingly it opens up the possibility of tuning the susceptibility and monitoring the tunnel coupling among the wells.

Oxidation of Molecular Hydrogen by a Chemolithoautotrophic Beggiatoa Strain

PubMed Central

2016-01-01

ABSTRACT A chemolithoautotrophic strain of the family Beggiatoaceae, Beggiatoa sp. strain 35Flor, was found to oxidize molecular hydrogen when grown in a medium with diffusional gradients of oxygen, sulfide, and hydrogen. Microsensor profiles and rate measurements suggested that the strain oxidized hydrogen aerobically when oxygen was available, while hydrogen consumption under anoxic conditions was presumably driven by sulfur respiration. Beggiatoa sp. 35Flor reached significantly higher biomass in hydrogen-supplemented oxygen-sulfide gradient media, but hydrogen did not support growth of the strain in the absence of reduced sulfur compounds. Nevertheless, hydrogen oxidation can provide Beggiatoa sp. 35Flor with energy for maintenance and assimilatory purposes and may support the disposal of internally stored sulfur to prevent physical damage resulting from excessive sulfur accumulation. Our knowledge about the exposure of natural populations of Beggiatoaceae to hydrogen is very limited, but significant amounts of hydrogen could be provided by nitrogen fixation, fermentation, and geochemical processes in several of their typical habitats such as photosynthetic microbial mats and submarine sites of hydrothermal fluid flow. IMPORTANCE Reduced sulfur compounds are certainly the main electron donors for chemolithoautotrophic Beggiatoaceae, but the traditional focus on this topic has left other possible inorganic electron donors largely unexplored. In this paper, we provide evidence that hydrogen oxidation has the potential to strengthen the ecophysiological plasticity of Beggiatoaceae in several ways. Moreover, we show that hydrogen oxidation by members of this family can significantly influence biogeochemical gradients and therefore should be considered in environmental studies. PMID:26896131

Hydrogen Bonding: Between Strengthening the Crystal Packing and Improving Solubility of Three Haloperidol Derivatives.

PubMed

Saluja, Hardeep; Mehanna, Ahmed; Panicucci, Riccardo; Atef, Eman

2016-06-01

The purpose of this study is to confirm the impact of polar functional groups on inter and intra-molecular hydrogen bonding in haloperidol (HP) and droperidol (DP) and, hence, their effects on dissolution using a new approach. To confirm our theory, a new molecule: deshydroxy-haloperidol (DHP) was designed and its synthesis was requested from a contract laboratory. The molecule was then studied and compared to DP and HP. Unlike DHP, both the HP and DP molecules have hydrogen donor groups, therefore, DHP was used to confirm the relative effects of the hydrogen donor group on solubility and crystal packing. The solid dispersions of the three structurally related molecules: HP, DP, and DHP were prepared using PVPK30, and characterized using XRPD and IR. A comparative dissolution study was carried out in aqueous medium. The absence of a hydrogen bonding donor group in DHP resulted in an unexpected increase in its aqueous solubility and dissolution rate from solid dispersion, which is attributed to weaker crystal pack. The increased dissolution rate of HP and DP from solid dispersions is attributed to drug-polymer hydrogen bonding that interferes with the drug-drug intermolecular hydrogen bonding and provides thermodynamic stability of the dispersed drug molecules. The drug-drug intermolecular hydrogen bond is the driving force for precipitation and crystal packing.

Hydrogen and formate oxidation coupled to dissimilatory reduction of iron or manganese by Alteromonas putrefaciens

USGS Publications Warehouse

Lovley, D.R.; Phillips, E.J.P.; Lonergan, D.J.

1989-01-01

The ability of Alteromonas putrefaciens to obtain energy for growth by coupling the oxidation of various electron donors to dissimilatory Fe(III) or Mn(IV) reduction was investigated. A. putrefaciens grew with hydrogen, formate, lactate, or pyruvate as the sole electron donor and Fe(III) as the sole electron acceptor. Lactate and pyruvate were oxidized to acetate, which was not metabolized further. With Fe(III) as the electron acceptor, A. putrefaciens had a high affinity for hydrogen and formate and metabolized hydrogen at partial pressures that were 25-fold lower than those of hydrogen that can be metabolized by pure cultures of sulfate reducers or methanogens. The electron donors for Fe(III) reduction also supported Mn(IV) reduction. The electron donors for Fe(III) and Mn(IV) reduction and the inability of A. putrefaciens to completely oxidize multicarbon substrates to carbon dioxide distinguish A. putrefaciens from GS-15, the only other organism that is known to obtain energy for growth by coupling the oxidation of organic compounds to the reduction of Fe(III) or Mn(IV). The ability of A. putrefaciens to reduce large quantities of Fe(III) and to grow in a defined medium distinguishes it from a Pseudomonas sp., which is the only other known hydrogen-oxidizing, Fe(III)-reducing microorganism. Furthermore, A. putrefaciens is the first organism that is known to grow with hydrogen as the electron donor and Mn(IV) as the electron acceptor and is the first organism that is known to couple the oxidation of formate to the reduction of Fe(III) or Mn(IV). Thus, A. putrefaciens provides a much needed microbial model for key reactions in the oxidation of sediment organic matter coupled to Fe(III) and Mn(IV) reduction.

Tandem ring-closing metathesis/transfer hydrogenation: practical chemoselective hydrogenation of alkenes.

PubMed

Connolly, Timothy; Wang, Zhongyu; Walker, Michael A; McDonald, Ivar M; Peese, Kevin M

2014-09-05

An operationally simple chemoselective transfer hydrogenation of alkenes using ruthenium metathesis catalysts is presented. Of great practicality, the transfer hydrogenation reagents can be added directly to a metathesis reaction and effect hydrogenation of the product alkene in a single pot at ambient temperature without the need to seal the vessel to prevent hydrogen gas escape. The reduction is applicable to a range of alkenes and can be performed in the presence of aryl halides and benzyl groups, a notable weakness of Pd-catalyzed hydrogenations. Scope and mechanistic considerations are presented.

Iridium-Catalyzed Hydrogen Transfer Reactions

NASA Astrophysics Data System (ADS)

Saidi, Ourida; Williams, Jonathan M. J.

This chapter describes the application of iridium complexes to catalytic hydrogen transfer reactions. Transfer hydrogenation reactions provide an alternative to direct hydrogenation for the reduction of a range of substrates. A hydrogen donor, typically an alcohol or formic acid, can be used as the source of hydrogen for the reduction of carbonyl compounds, imines, and alkenes. Heteroaromatic compounds and even carbon dioxide have also been reduced by transfer hydrogenation reactions. In the reverse process, the oxidation of alcohols to carbonyl compounds can be achieved by iridium-catalyzed hydrogen transfer reactions, where a ketone or alkene is used as a suitable hydrogen acceptor. The reversible nature of many hydrogen transfer processes has been exploited for the racemization of alcohols, where temporary removal of hydrogen generates an achiral ketone intermediate. In addition, there is a growing body of work where temporary removal of hydrogen provides an opportunity for using alcohols as alkylating agents. In this chemistry, an iridium catalyst "borrows" hydrogen from an alcohol to give an aldehyde or ketone intermediate, which can be transformed into either an imine or alkene under the reaction conditions. Return of the hydrogen from the catalyst provides methodology for the formation of amines or C-C bonds where the only by-product is typically water.

Predictive Models for the Free Energy of Hydrogen Bonded Complexes with Single and Cooperative Hydrogen Bonds.

PubMed

Glavatskikh, Marta; Madzhidov, Timur; Solov'ev, Vitaly; Marcou, Gilles; Horvath, Dragos; Varnek, Alexandre

2016-12-01

In this work, we report QSPR modeling of the free energy ΔG of 1 : 1 hydrogen bond complexes of different H-bond acceptors and donors. The modeling was performed on a large and structurally diverse set of 3373 complexes featuring a single hydrogen bond, for which ΔG was measured at 298 K in CCl 4 . The models were prepared using Support Vector Machine and Multiple Linear Regression, with ISIDA fragment descriptors. The marked atoms strategy was applied at fragmentation stage, in order to capture the location of H-bond donor and acceptor centers. Different strategies of model validation have been suggested, including the targeted omission of individual H-bond acceptors and donors from the training set, in order to check whether the predictive ability of the model is not limited to the interpolation of H-bond strength between two already encountered partners. Successfully cross-validating individual models were combined into a consensus model, and challenged to predict external test sets of 629 and 12 complexes, in which donor and acceptor formed single and cooperative H-bonds, respectively. In all cases, SVM models outperform MLR. The SVM consensus model performs well both in 3-fold cross-validation (RMSE=1.50 kJ/mol), and on the external test sets containing complexes with single (RMSE=3.20 kJ/mol) and cooperative H-bonds (RMSE=1.63 kJ/mol). © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ground-state splitting of ultrashallow thermal donors with negative central-cell corrections in silicon

NASA Astrophysics Data System (ADS)

Hara, Akito; Awano, Teruyoshi

2017-06-01

Ultrashallow thermal donors (USTDs), which consist of light element impurities such as carbon, hydrogen, and oxygen, have been found in Czochralski silicon (CZ Si) crystals. To the best of our knowledge, these are the shallowest hydrogen-like donors with negative central-cell corrections in Si. We observed the ground-state splitting of USTDs by far-infrared optical absorption at different temperatures. The upper ground-state levels are approximately 4 meV higher than the ground-state levels. This energy level splitting is also consistent with that obtained by thermal excitation from the ground state to the upper ground state. This is direct evidence that the wave function of the USTD ground state is made up of a linear combination of conduction band minimums.

Non-Heart-Beating Donor Program: Results After 3 Years of Experience.

PubMed

Martin-Villen, L; Revuelto-Rey, J; Aldabo-Pallas, T; Correa-Chamorro, E; Gallego-Corpa, A; Ruiz Del Portal-Ruiz Granados, P; Roncero-Rodriguez, M A; Egea-Guerrero, J J

2015-11-01

Non-heart-beating donation (NHBD) is a useful way to obtain organs and tissues. Therefore, since 2012 we have had an NHBD protocol in the metropolitan area of Seville. The aim of this work was to present the results obtained after 3 years of program. Prospective observational study carried out from 2012 to 2014. We included all patients with an extrahospitalary sudden death who did not survive despite cardiopulmonary resuscitation, becoming a potential donors (PD). Variables included number of consultations, PD, allowed donor (AD), real donor (RD), and family or legal refusals; minutes of out-hospital care, in-hospital care, cannulation, and perfusion of the RD; and number of organs and tissues removed and viable proportion. Nonallowed donors were grouped according to the discarding cause. We received 97 consultations, of which 40 were performed as PD. Of these, 24 were AD (60%) and 22 RD (55%). There were only 2 family refusals. In 2012, 10 patients were donors, 5 in 2013, and 7 in 2014. The out-hospital median time was 71 (interquartile range [IQR] 60-76) minutes, in-hospital 29 (26-34) minutes, cannulation 28 (24-33) minutes, and perfusion 135 (105-177) minutes. Eighteen tissues and 43 organs were extracted, of which 32 were implanted (75%), with kidneys (96%) being more frequent. Nonallowed donors numbered 12 in 2012, 4 in 2013, and 1 in 2014, and out-hospital causes were the most frequent discard reason. NHBD is a useful program in our city with a low refusal rate (8%), an average of 1.45 organs per donor, and kidney the most frequent organ. Copyright © 2015 Elsevier Inc. All rights reserved.

[Regulatory problems regarding bone marrow transplantation from non-consanguinous donors].

PubMed

Moratti, A

1999-01-01

The paper reports the normative rules and the Italian Ministry of Health administrative instructions concerning the bone marrow unrelated donor (MUD) search in the Italian Bone Marrow Donor Registry (IBMDR) and in international registries from the preliminary activation to a MUD bone marrow transplant (BMT), when a volunteer donor, perfectly compatible with a recipient lacking a HLA identical sibling, is found. The article describes all the expenses pertinent to the different stages of search and the documents necessary to obtain the reimbursement of these expenses. A very recent Ministry Decree establishing that all the search costs will be charged to the competent local sanitary authority is added.

Bond-center hydrogen in dilute Si1-xGex alloys: Laplace deep-level transient spectroscopy

NASA Astrophysics Data System (ADS)

Bonde Nielsen, K.; Dobaczewski, L.; Peaker, A. R.; Abrosimov, N. V.

2003-07-01

We apply Laplace deep-level transient spectroscopy in situ after low-temperature proton implantation into dilute Si1-xGex alloys and identify the deep donor state of hydrogen occupying a strained Si-Si bond-center site next to Ge. The activation energy of the electron emission from the donor is ˜158 meV when extrapolated to zero electrical field. We construct a configuration diagram of the Ge-strained site from formation and annealing data and deduce that alloying with ˜1% Ge does not significantly influence the low-temperature migration of hydrogen as compared to elemental Si. We observe two bond-center-type carbon-hydrogen centers and conclude that carbon impurities act as much stronger traps for hydrogen than the alloy Ge atoms.

Carbon Monoxide as an Electron Donor for the Biological Reduction of Sulphate

PubMed Central

Parshina, Sofiya N.; Sipma, Jan; Henstra, Anne Meint; Stams, Alfons J. M.

2010-01-01

Several strains of Gram-negative and Gram-positive sulphate-reducing bacteria (SRB) are able to use carbon monoxide (CO) as a carbon source and electron donor for biological sulphate reduction. These strains exhibit variable resistance to CO toxicity. The most resistant SRB can grow and use CO as an electron donor at concentrations up to 100%, whereas others are already severely inhibited at CO concentrations as low as 1-2%. Here, the utilization, inhibition characteristics, and enzymology of CO metabolism as well as the current state of genomics of CO-oxidizing SRB are reviewed. Carboxydotrophic sulphate-reducing bacteria can be applied for biological sulphate reduction with synthesis gas (a mixture of hydrogen and carbon monoxide) as an electron donor. PMID:20628586

Photoreduction of Azoalkanes by Direct Hydrogen Abstraction from 1,4-Cyclohexadiene, Alcohols, Stannanes, and Silanes.

PubMed

Adam, Waldemar; Moorthy, Jarugu N.; Nau, Werner M.; Scaiano, J. C.

1997-11-14

A mechanistic investigation of the photoreduction of the n,pi triplet-excited azo chromophore has been carried out on azoalkanes 1, which exhibit efficient intersystem-crossing quantum yields (ca. 0.5). The azoalkanes 1a and 1b undergo facile photoreduction to the corresponding hydrazines in the presence of a variety of hydrogen donors, which include 2-propanol, benzhydrol, 1,4-cyclohexadiene, tributylstannane, and tris(trimethylsilyl)silane. In contrast, the hydrazine yields derived for the azoalkanes 1c and 1d are significantly lower even at high hydrogen donor concentrations due to their lower triplet yields and shorter triplet lifetimes. A clear dependence of the hydrazine yields on the bond dissociation energies of the hydrogen donors has been observed, which is reflected in the quenching rate constants obtained from time-resolved transient absorption spectroscopy. The absolute rate constants for interaction of the triplet azoalkane 1a with hydrogen donors are generally lower (ca. 10-100-fold) than for benzophenone, in line with the less favorable reaction thermodynamics. The comparison of the rate constants for quenching of the triplet-excited azoalkane 1a and of the singlet-excited state of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) reveals a similar reactivity of excited azoalkanes toward hydrogen donors; differences can be accounted for in terms of variations in the energies of the excited states. The interactions of the excited azoalkanes with tributylstannane and benzhydrol produce the radicals characteristic for hydrogen abstraction from these substrates, namely tributylstannyl and hydroxydiphenylmethyl radicals, which were detected through their transient absorptions at 390 and 550 nm, respectively. Interestingly, compared to the photoreduction of benzophenone with benzhydrol, for which the quantum yield for conversion to radicals is unity, between the azoalkane 1a and benzhydrol this efficiency is only ca. 12%. An associative effect through N.H-O bonding

Production and Consumption of Hydrogen in Hot Spring Microbial Mats Dominated by a Filamentous Anoxygenic Photosynthetic Bacterium

PubMed Central

Otaki, Hiroyo; Everroad, R. Craig; Matsuura, Katsumi; Haruta, Shin

2012-01-01

Microbial mats containing the filamentous anoxygenic photosynthetic bacterium Chloroflexus aggregans develop at Nakabusa hot spring in Japan. Under anaerobic conditions in these mats, interspecies interaction between sulfate-reducing bacteria as sulfide producers and C. aggregans as a sulfide consumer has been proposed to constitute a sulfur cycle; however, the electron donor utilized for microbial sulfide production at Nakabusa remains to be identified. In order to determine this electron donor and its source, ex situ experimental incubation of mats was explored. In the presence of molybdate, which inhibits biological sulfate reduction, hydrogen gas was released from mat samples, indicating that this hydrogen is normally consumed as an electron donor by sulfate-reducing bacteria. Hydrogen production decreased under illumination, indicating that C. aggregans also functions as a hydrogen consumer. Small amounts of hydrogen may have also been consumed for sulfur reduction. Clone library analysis of 16S rRNA genes amplified from the mats indicated the existence of several species of hydrogen-producing fermentative bacteria. Among them, the most dominant fermenter, Fervidobacterium sp., was successfully isolated. This isolate produced hydrogen through the fermentation of organic carbon. Dispersion of microbial cells in the mats resulted in hydrogen production without the addition of molybdate, suggesting that simultaneous production and consumption of hydrogen in the mats requires dense packing of cells. We propose a cyclic electron flow within the microbial mats, i.e., electron flow occurs through three elements: S (elemental sulfur, sulfide, sulfate), C (carbon dioxide, organic carbon) and H (di-hydrogen, protons). PMID:22446313

Lung inflation with hydrogen during the cold ischemia phase decreases lung graft injury in rats

PubMed Central

Liu, Rongfang; Fang, Xianhai; Meng, Chao; Xing, Jingchun; Liu, Jinfeng; Yang, Wanchao

2015-01-01

Hydrogen has antioxidant and anti-inflammatory effects on lung ischemia–reperfusion injury when it is inhaled by donor or/and recipient. This study examined the effects of lung inflation with 3% hydrogen during the cold ischemia phase on lung graft function in rats. The donor lung was inflated with 3% hydrogen, 40% oxygen, and 57% nitrogen at 5 mL/kg, and the gas was replaced every 20 min during the cold ischemia phase for 2 h. In the control group, the donor lung was inflated with 40% oxygen and 60% nitrogen at 5 mL/kg. The recipient was euthanized 2 h after orthotropic lung transplantation. The hydrogen concentration in the donor lung during the cold ischemia phase was 1.99–3%. The oxygenation indices in the arterial blood and pulmonary vein blood were improved in the hydrogen group. The inflammation response indices, including lung W/D ratio, the myeloperoxidase activity in the grafts, and the levels of IL-8 and TNF-α in serum, were significantly lower in the hydrogen group (5.2 ± 0.8, 0.76 ± 0.32 U/g, 340 ± 84 pg/mL, and 405 ± 115 pg/mL, respectively) than those in the control group (6.5 ± 0.7, 1.1 ± 0.5 U/g, 443 ± 94 pg/mL, and 657 ± 96 pg/mL, respectively (P < 0.05), and the oxidative stress indices, including the superoxide dismutase activity and the level of malonaldehyde in lung grafts were improved after hydrogen application. Furthermore, the lung injury score determined by histopathology, the cell apoptotic index, and the caspase-3 protein expression in lung grafts were decreased after hydrogen treatment, and the static pressure–volume curve of lung graft was improved by hydrogen inflation. In conclusion, lung inflation with 3% hydrogen during the cold ischemia phase alleviated lung graft injury and improved graft function. PMID:25662956

A theoretical study of the effect of a non-aqueous proton donor on electrochemical ammonia synthesis

DOE PAGES

Zhang, Linan; Mallikarjun Sharada, Shaama; Singh, Aayush R.; ...

2018-01-17

We report that ammonia synthesis is one of the most studied reactions in heterogeneous catalysis. To date, however, electrochemical N 2 reduction in aqueous systems has proven to be extremely difficult, mainly due to the competing hydrogen evolution reaction (HER). Recently, it has been shown that transition metal complexes based on molybdenum can reduce N 2 to ammonia at room temperature and ambient pressure in a non-aqueous system, with a relatively small amount of hydrogen output. We demonstrate that the non-aqueous proton donor they have chosen, 2,6-lutidinium (LutH +), is a viable substitute for hydronium in the electrochemical process atmore » a solid surface, since this donor can suppress the HER rate. Finally, we also show that the presence of LutH + can selectively stabilize the *NNH intermediate relative to *NH or *NH 2via the formation of hydrogen bonds, indicating that the use of non-aqueous solvents can break the scaling relationship between limiting potential and binding energies.« less

A theoretical study of the effect of a non-aqueous proton donor on electrochemical ammonia synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Linan; Mallikarjun Sharada, Shaama; Singh, Aayush R.

We report that ammonia synthesis is one of the most studied reactions in heterogeneous catalysis. To date, however, electrochemical N 2 reduction in aqueous systems has proven to be extremely difficult, mainly due to the competing hydrogen evolution reaction (HER). Recently, it has been shown that transition metal complexes based on molybdenum can reduce N 2 to ammonia at room temperature and ambient pressure in a non-aqueous system, with a relatively small amount of hydrogen output. We demonstrate that the non-aqueous proton donor they have chosen, 2,6-lutidinium (LutH +), is a viable substitute for hydronium in the electrochemical process atmore » a solid surface, since this donor can suppress the HER rate. Finally, we also show that the presence of LutH + can selectively stabilize the *NNH intermediate relative to *NH or *NH 2via the formation of hydrogen bonds, indicating that the use of non-aqueous solvents can break the scaling relationship between limiting potential and binding energies.« less

Support of Unrelated Stem Cell Donor Searches by Donor Center-Initiated HLA Typing of Potentially Matching Donors

PubMed Central

Schmidt, Alexander H.; Solloch, Ute V.; Baier, Daniel; Grathwohl, Alois; Hofmann, Jan; Pingel, Julia; Stahr, Andrea; Ehninger, Gerhard

2011-01-01

Large registries of potential unrelated stem cell donors have been established in order to enable stem cell transplantation for patients without HLA-identical related donors. Donor search is complicated by the fact that the stored HLA information of many registered donors is incomplete. We carried out a project that was aimed to improve chances of patients with ongoing donor searches to find an HLA-matched unrelated donor. For that purpose, we carried out additional donor center-initiated HLA-DRB1 typing of donors who were only typed for the HLA loci A and B so far and were potential matches for patients in need of a stem cell transplant. In total, 8,861 donors were contacted for donor center-initiated HLA-DRB1 typing within 1,089 donor searches. 12 of these donors have donated stem cells so far, 8 thereof for their respective target patients. We conclude that chances of patients with ongoing donor searches to find an HLA-matched unrelated donor can indeed be improved by donor-center initiated typing that is carried out in addition to the standard donor search process. Our results also raise questions regarding the appropriate use of incompletely typed donors within unrelated donor searches. PMID:21625451

Costs of Storing and Transporting Hydrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amos, W. A.

An analysis was performed to estimate the costs associated with storing and transporting hydrogen. These costs can be added to a hydrogen production cost to determine the total delivered cost of hydrogen. Storage methods analyzed included compressed gas, liquid hydrogen, metal hydride, and underground storage. Major capital and operating costs were considered over a range of production rates and storage times.

Voluntary whole-blood donors, and compensated platelet donors and plasma donors: motivation to donate, altruism and aggression.

PubMed

Trimmel, Michael; Lattacher, Helene; Janda, Monika

2005-10-01

To establish if voluntary whole-blood donors and compensated platelet donors and plasma donors may differ in their motivation to donate, altruism, aggression and autoaggression. Whole-blood (n=51), platelet (n=52) and plasma donors (n=48) completed a battery of validated questionnaires while waiting to donate. Bivariate and multivariate analyses of variance and t-tests were performed to detect differences between groups as noted. Altruism (mean=40.2) was slightly higher in whole-blood donors than in platelet (mean=38.3) and plasma donors (mean=39.1) (p=0.07). Blood donors (mean=2.8) scored lower in the spontaneous aggression measure than platelet (mean=4.1) and plasma donors (mean=4.4) (p=0.01). Plasma donors (mean=4.9) had higher auto-aggression than whole-blood donors and platelet donors (mean for both groups=3.4) (p=0.01). Differences between the three groups were mediated by sociodemographic variables (MANCOVA). Whole-blood donors donated to help others, platelet and plasma donors mostly to receive the compensation. However, those platelet and plasma donors, who would continue to donate without compensation were similar in altruism and aggression to whole-blood donors. While most platelet donors and plasma donors were motivated by the compensation, those who stated that they would continue to donate without compensation had altruism and aggression scores similar to voluntary whole-blood donors.

Electron Donor-Acceptor Nature of the Ethanol-CO2 Dimer

NASA Astrophysics Data System (ADS)

McGuire, Brett A.; Martin-Drumel, Marie-Aline; McCarthy, Michael A.

2017-08-01

Supercritical CO2 is an appealing nontoxic, environmentally friendly solvent for the industrial extraction of many classes of compounds, from caffeine to natural product drug precursors to petrochemical impurities. Apolar in isolation, the ability of supercritical CO2 to dissolve polar species has been empirically shown to be greatly enhanced by the addition of a small molar percentage of a polar cosolvent, often ethanol. Computational work predicts that the isolated ethanol-CO2 complex can exist either in an electron-donor configuration or through a hydrogen-bonding one; yet, neither has been previously experimentally observed. Here, we demonstrate by rotational spectroscopy that the isolated, gas-phase ethanol-CO2 dimer is an electron donor-acceptor complex.

Cocrystals of 5-fluorocytosine. I. Coformers with fixed hydrogen-bonding sites.

PubMed

Tutughamiarso, Maya; Wagner, Guido; Egert, Ernst

2012-08-01

The antifungal drug 5-fluorocytosine (4-amino-5-fluoro-1,2-dihydropyrimidin-2-one) was cocrystallized with five complementary compounds in order to better understand its drug-receptor interaction. The first two compounds, 2-aminopyrimidine (2-amino-1,3-diazine) and N-acetylcreatinine (N-acetyl-2-amino-1-methyl-5H-imidazol-4-one), exhibit donor-acceptor sites for R(2)(2)(8) heterodimer formation with 5-fluorocytosine. Such a heterodimer is observed in the cocrystal with 2-aminopyrimidine (I); in contrast, 5-fluorocytosine and N-acetylcreatinine [which forms homodimers in its crystal structure (II)] are connected only by a single hydrogen bond in (III). The other three compounds 6-aminouracil (6-amino-2,4-pyrimidinediol), 6-aminoisocytosine (2,6-diamino-3H-pyrimidin-4-one) and acyclovir [acycloguanosine or 2-amino-9-[(2-hydroxyethoxy)methyl]-1,9-dihydro-6H-purin-6-one] possess donor-donor-acceptor sites; therefore, they can interact with 5-fluorocytosine to form a heterodimer linked by three hydrogen bonds. In the cocrystals with 6-aminoisocytosine (Va)-(Vd), as well as in the cocrystal with the antiviral drug acyclovir (VII), the desired heterodimers are observed. However, they are not formed in the cocrystal with 6-aminouracil (IV), where the components are connected by two hydrogen bonds. In addition, a solvent-free structure of acyclovir (VI) was obtained. A comparison of the calculated energies released during dimer formation helped to rationalize the preference for hydrogen-bonding interactions in the various cocrystal structures.

Development and Characterization of Titanium Dioxide Gel with Encapsulated Bacteriorhodopsin for Hydrogen Production.

PubMed

Johnson, Kaitlin E; Gakhar, Sukriti; Risbud, Subhash H; Longo, Marjorie L

2018-06-06

We study bacteriorhodopsin (BR) in its native purple membrane encapsulated within amorphous titanium dioxide, or titania, gels and in the presence of titania sol-particles to explore this system for hydrogen production. Förster resonance energy transfer between BR and titanium dioxide sol particles was used to conclude that there is nanometer-scale proximity of bacteriorhodopsin to the titanium dioxide. The detection of BR-titania sol aggregates by fluorescence anisotropy and particle sizing indicated the affinity amorphous titania has for BR without the use of additional cross-linkers. UV-Visible spectroscopy of BR-titania gels show that methanol addition did not denature BR at a 25 mM concentration presence as a sacrificial electron donor. Additionally, confinement of BR in the gels significantly limited protein denaturation at higher concentration of added methanol or ethanol. Subsequently, titania gels fabricated through the sol-gel process using a titanium ethoxide precursor, water and the addition of 25 mM methanol were used to encapsulate BR and a platinum reduction catalyst for the production of hydrogen gas under white light irradiation. The inclusion of 5 µM bacteriorhodopsin resulted in a hydrogen production rate of about 3.8 µmole hydrogen mL -1 hr -1 , an increase of 52% compared to gels containing no protein. Electron transfer and proton pumping by BR in close proximity to the titania gel surface are feasible explanations for the enhanced production of hydrogen without the need to crosslink BR to the titania gel. This work sets the stage for further developments of amorphous, rather than crystalline, titania-encapsulated bacteriorhodopsin for solar-driven hydrogen production through water-splitting.

Improved bio-hydrogen production from glucose by adding a specific methane inhibitor to microbial electrolysis cells with a double anode arrangement.

PubMed

Zhang, Jingnan; Bai, Yanxia; Fan, Yaoting; Hou, Hongwei

2016-10-01

Improved hydrogen production from glucose was achieved by adding a specific methane inhibitor (such as chloroform) to repress the activity of methanogens in a single-chamber microbial electrolysis cells (MECs) with a double anode arrangement. A maximum hydrogen production of 8.4±0.2 mol H2/mol-G (G represents glucose), a hydrogen production rate of 2.39±0.3 m(3) H2/m3/d and a high energy efficiency (relative to the electrical input) of ηE=165±5% had been recorded from 1 g/L glucose at a low dosage of chloroform (5‰, v:v) and an applied voltage of 0.8 V. Almost all of the glucose was removed within 4 h, with 66% of the electrons in intermediates (mainly including acetate and ethanol), and methane gas was not detected in the MECs through 11 batch cycles. The experimental results confirmed that chloroform was an effective methane inhibitor that improved hydrogen production from glucose in the MECs. In addition, the cyclic voltammetry tests demonstrated that the electron transfer in the MECs was mainly due to the biofilm-bound redox compounds rather than soluble electron shuttles. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Synthesis, spectral characterization and structural studies of a novel O, N, O donor semicarbazone and its binuclear copper complex with hydrogen bond stabilized lattice

NASA Astrophysics Data System (ADS)

Layana, S. R.; Saritha, S. R.; Anitha, L.; Sithambaresan, M.; Sudarsanakumar, M. R.; Suma, S.

2018-04-01

A novel O,N,O donor salicylaldehyde-N4-phenylsemicarbazone, (H2L) has been synthesized and physicochemically characterized. Detailed structural studies of H2L using single crystal X-ray diffraction technique reveals the existence of intra and inter molecular hydrogen bonding interactions, which provide extra stability to the molecule. We have successfully synthesized a binuclear copper(II) complex, [Cu2(HL)2(NO3)(H2O)2]NO3 with phenoxy bridging between the two copper centers. The complex was characterized by elemental analysis, magnetic susceptibility and conductivity measurements, FT-IR, UV-Visible, mass and EPR spectral methods. The grown crystals of the copper complex were employed for the single crystal X-ray diffraction studies. The complex possesses geometrically different metal centers, in which the ligand coordinates through ketoamide oxygen, azomethine nitrogen and deprotonated phenoxy oxygen. The extensive intermolecular hydrogen bonding interactions of the coordinated and the lattice nitrate groups interconnect the complex units to form a 2D supramolecular assembly. The ESI mass spectrum substantiates the existence of 1:1 complex. The g values obtained from the EPR spectrum in frozen DMF suggest dx2 -y2 ground state for the unpaired electron.

Evaluation of process excellence tools in improving donor flow management in a tertiary care hospital in South India

PubMed Central

Venugopal, Divya; Rafi, Aboobacker Mohamed; Innah, Susheela Jacob; Puthayath, Bibin T.

2017-01-01

BACKGROUND: Process Excellence is a value based approach and focuses on standardizing work processes by eliminating the non-value added processes, identify process improving methodologies and maximize capacity and expertise of the staff. AIM AND OBJECTIVES: To Evaluate the utility of Process Excellence Tools in improving Donor Flow Management in a Tertiary care Hospital by studying the current state of donor movement within the blood bank and providing recommendations for eliminating the wait times and to improve the process and workflow. MATERIALS AND METHODS: The work was done in two phases; The First Phase comprised of on-site observations with the help of an expert trained in Process Excellence Methodology who observed and documented various aspects of donor flow, donor turn around time, total staff details and operator process flow. The Second Phase comprised of constitution of a Team to analyse the data collected. The analyzed data along with the recommendations were presented before an expert hospital committee and the management. RESULTS: Our analysis put forward our strengths and identified potential problems. Donor wait time was reduced by 50% after lean due to better donor management with reorganization of the infrastructure of the donor area. Receptionist tracking showed that 62% of the total time the staff wastes in walking and 22% in other non-value added activities. Defining Duties for each staff reduced the time spent by them in non-value added activities. Implementation of the token system, generation of unique identification code for donors and bar code labeling of the tubes and bags are among the other recommendations. CONCLUSION: Process Excellence is not a programme; it's a culture that transforms an organization and improves its Quality and Efficiency through new attitudes, elimination of wastes and reduction in costs. PMID:28970681

Evaluation of process excellence tools in improving donor flow management in a tertiary care hospital in South India.

PubMed

Venugopal, Divya; Rafi, Aboobacker Mohamed; Innah, Susheela Jacob; Puthayath, Bibin T

2017-01-01

Process Excellence is a value based approach and focuses on standardizing work processes by eliminating the non-value added processes, identify process improving methodologies and maximize capacity and expertise of the staff. To Evaluate the utility of Process Excellence Tools in improving Donor Flow Management in a Tertiary care Hospital by studying the current state of donor movement within the blood bank and providing recommendations for eliminating the wait times and to improve the process and workflow. The work was done in two phases; The First Phase comprised of on-site observations with the help of an expert trained in Process Excellence Methodology who observed and documented various aspects of donor flow, donor turn around time, total staff details and operator process flow. The Second Phase comprised of constitution of a Team to analyse the data collected. The analyzed data along with the recommendations were presented before an expert hospital committee and the management. Our analysis put forward our strengths and identified potential problems. Donor wait time was reduced by 50% after lean due to better donor management with reorganization of the infrastructure of the donor area. Receptionist tracking showed that 62% of the total time the staff wastes in walking and 22% in other non-value added activities. Defining Duties for each staff reduced the time spent by them in non-value added activities. Implementation of the token system, generation of unique identification code for donors and bar code labeling of the tubes and bags are among the other recommendations. Process Excellence is not a programme; it's a culture that transforms an organization and improves its Quality and Efficiency through new attitudes, elimination of wastes and reduction in costs.

Cocrystals of 6-methyl-2-thiouracil: presence of the acceptor-donor-acceptor/donor-acceptor-donor synthon.

PubMed

Hützler, Wilhelm Maximilian; Egert, Ernst

2015-03-01

The results of seven cocrystallization experiments of the antithyroid drug 6-methyl-2-thiouracil (MTU), C(5)H(6)N(2)OS, with 2,4-diaminopyrimidine, 2,4,6-triaminopyrimidine and 6-amino-3H-isocytosine (viz. 2,6-diamino-3H-pyrimidin-4-one) are reported. MTU features an ADA (A = acceptor and D = donor) hydrogen-bonding site, while the three coformers show complementary DAD hydrogen-bonding sites and therefore should be capable of forming an ADA/DAD N-H...O/N-H...N/N-H...S synthon with MTU. The experiments yielded one cocrystal and six cocrystal solvates, namely 6-methyl-2-thiouracil-2,4-diaminopyrimidine-1-methylpyrrolidin-2-one (1/1/2), C(5)H(6)N(2)OS·C(4)H(6)N(4)·2C(5)H(9)NO, (I), 6-methyl-2-thiouracil-2,4-diaminopyrimidine (1/1), C(5)H(6)N(2)OS·C(4)H(6)N(4), (II), 6-methyl-2-thiouracil-2,4-diaminopyrimidine-N,N-dimethylacetamide (2/1/2), 2C(5)H(6)N(2)OS·C(4)H(6)N(4)·2C(4)H(9)NO, (III), 6-methyl-2-thiouracil-2,4-diaminopyrimidine-N,N-dimethylformamide (2/1/2), C(5)H(6)N(2)OS·0.5C(4)H(6)N(4)·C(3)H(7)NO, (IV), 2,4,6-triaminopyrimidinium 6-methyl-2-thiouracilate-6-methyl-2-thiouracil-N,N-dimethylformamide (1/1/2), C(4)H(8)N(5)(+)·C(5)H(5)N(2)OS(-)·C(5)H(6)N(2)OS·2C(3)H(7)NO, (V), 6-methyl-2-thiouracil-6-amino-3H-isocytosine-N,N-dimethylformamide (1/1/1), C(5)H(6)N(2)OS·C(4)H(6)N(4)O·C(3)H(7)NO, (VI), and 6-methyl-2-thiouracil-6-amino-3H-isocytosine-dimethyl sulfoxide (1/1/1), C(5)H(6)N(2)OS·C(4)H(6)N(4)O·C(2)H(6)OS, (VII). Whereas in cocrystal (I) an R(2)(2)(8) interaction similar to the Watson-Crick adenine/uracil base pair is formed and a two-dimensional hydrogen-bonding network is observed, the cocrystals (II)-(VII) contain the triply hydrogen-bonded ADA/DAD N-H...O/N-H...N/N-H...S synthon and show a one-dimensional hydrogen-bonding network. Although 2,4-diaminopyrimidine possesses only one DAD hydrogen-bonding site, it is, due to orientational disorder, triply connected to two MTU molecules in (III) and (IV).

Comparison of Alternative Hydrogen Donors for Anaerobic Reductive Dechlorination of Tetrachloroethene

DTIC Science & Technology

1998-01-01

feature two - stage anaerobic reductive dechlorination of highly chlorinated compounds coupled with aerobic (sometimes co- metabolic) treatment of the...activity at some naturally attenuated sites. Fathepure and Vogel [76] used a two - stage anaerobic-aerobic reactor system to treat hexachlorobenzene, PCE...Complete removal of the chloroethenes by the two - stage system was observed using pyruvate, formate, or lactose as electron donor for the dechlorinating

Donor Outcomes in Living Donor Liver Transplantation-Analysis of 275 Donors From a Single Centre in India.

PubMed

Narasimhan, Gomathy; Safwan, Mohamed; Kota, Venugopal; Reddy, Mettu S; Bharathan, Anand; Dabora, Abderrhaim; Kaliamoorthy, Ilankumaran; Kanagavelu, Rathnavel G; Srinivasan, Vijaya; Rela, Mohamed

2016-06-01

Live donor liver transplantation is the predominant form of liver transplantation in India and in most Asian countries. Donor outcome reports are an important source of information to be shared with prospective donors at the time of informed consent. This is the first donor outcome series from India. Analysis of donor characteristics and morbidity of 275 live donors from a single large volume center is documented. Two hundred seventy-five patients donated from November 2009 to October 2014, 144 were women and 131 were men, 180 donated to adults and 95 donated to children. Right lobe donors were majority at 62.2% followed by left lateral segment 28%. Two thirds of the live donors did not have any morbidity; 114 complications were encountered in 85 patients. The complications were graded as per Clavien 5 tier grading and major morbidity (grade III b, grade IV grade V) was 4.36%. Postoperative biliary complication was seen in 3 donors. This large single-center study is the first donor outcome report from India, and the results are comparable to other published donor series. Documentation and regular audit of donor outcomes is important to help improve the safety of donor hepatectomy and to provide a database for informed consent of prospective donors.

Protein-ligand interfaces are polarized: discovery of a strong trend for intermolecular hydrogen bonds to favor donors on the protein side with implications for predicting and designing ligand complexes.

PubMed

Raschka, Sebastian; Wolf, Alex J; Bemister-Buffington, Joseph; Kuhn, Leslie A

2018-04-01

Understanding how proteins encode ligand specificity is fascinating and similar in importance to deciphering the genetic code. For protein-ligand recognition, the combination of an almost infinite variety of interfacial shapes and patterns of chemical groups makes the problem especially challenging. Here we analyze data across non-homologous proteins in complex with small biological ligands to address observations made in our inhibitor discovery projects: that proteins favor donating H-bonds to ligands and avoid using groups with both H-bond donor and acceptor capacity. The resulting clear and significant chemical group matching preferences elucidate the code for protein-native ligand binding, similar to the dominant patterns found in nucleic acid base-pairing. On average, 90% of the keto and carboxylate oxygens occurring in the biological ligands formed direct H-bonds to the protein. A two-fold preference was found for protein atoms to act as H-bond donors and ligand atoms to act as acceptors, and 76% of all intermolecular H-bonds involved an amine donor. Together, the tight chemical and geometric constraints associated with satisfying donor groups generate a hydrogen-bonding lock that can be matched only by ligands bearing the right acceptor-rich key. Measuring an index of H-bond preference based on the observed chemical trends proved sufficient to predict other protein-ligand complexes and can be used to guide molecular design. The resulting Hbind and Protein Recognition Index software packages are being made available for rigorously defining intermolecular H-bonds and measuring the extent to which H-bonding patterns in a given complex match the preference key.

Protein-ligand interfaces are polarized: discovery of a strong trend for intermolecular hydrogen bonds to favor donors on the protein side with implications for predicting and designing ligand complexes

NASA Astrophysics Data System (ADS)

Raschka, Sebastian; Wolf, Alex J.; Bemister-Buffington, Joseph; Kuhn, Leslie A.

2018-02-01

Understanding how proteins encode ligand specificity is fascinating and similar in importance to deciphering the genetic code. For protein-ligand recognition, the combination of an almost infinite variety of interfacial shapes and patterns of chemical groups makes the problem especially challenging. Here we analyze data across non-homologous proteins in complex with small biological ligands to address observations made in our inhibitor discovery projects: that proteins favor donating H-bonds to ligands and avoid using groups with both H-bond donor and acceptor capacity. The resulting clear and significant chemical group matching preferences elucidate the code for protein-native ligand binding, similar to the dominant patterns found in nucleic acid base-pairing. On average, 90% of the keto and carboxylate oxygens occurring in the biological ligands formed direct H-bonds to the protein. A two-fold preference was found for protein atoms to act as H-bond donors and ligand atoms to act as acceptors, and 76% of all intermolecular H-bonds involved an amine donor. Together, the tight chemical and geometric constraints associated with satisfying donor groups generate a hydrogen-bonding lock that can be matched only by ligands bearing the right acceptor-rich key. Measuring an index of H-bond preference based on the observed chemical trends proved sufficient to predict other protein-ligand complexes and can be used to guide molecular design. The resulting Hbind and Protein Recognition Index software packages are being made available for rigorously defining intermolecular H-bonds and measuring the extent to which H-bonding patterns in a given complex match the preference key.

Cost analysis of living donor liver transplantation: the first Italian economical data.

PubMed

Passarani, S; De Carlis, L; Maione, G; Alberti, A B; Bevilacqua, L; Baraldi, S

2007-10-01

Over a period of 30 months, the Niguarda Ca'Granda Hospital performed 12 living donor liver transplants (LDLT) on adult subjects using the split-liver technique and transplant of the right lobe. The purpose of this work is to evaluate the financial obligation that this technique will bring, the ethical and cultural aspects, and the mortality related to surgery on a healthy donor whose only reward is in the knowledge of having done everything possible for a loved family member. The analysis of the costs of the surgical process takes into account the simultaneous consideration of both types of patients: the donor and the recipient. The diagnostic course is subdivided into seven functional phases of the cost centers, and the transitory sequences of the foreseeable events of the entire process. The method used consists in the appraisal of all the clinical activities in chronological order several the centers of cost. The direct expenses are evaluated according to an analytical method, and the indirect costs has been carried out on the criterion of the activities of support to the process (management of the orders, recording and programming of the activities) and support to the organization (maintenance, management supplying and contests of contract, programming of the business production, management warehouses, supplyings, marketing and relations with the public). The cost of all the patients evaluated that were not able to donate has been added to the direct expenses of 12 donor and 12 recipient patients, in all 30 patients, so as to shift the added expenses only to the donor patient, since these costs are not included in the typical costs of transplantation from a cadaver. The indirect cost calculated for each patient has been added to the direct costs of the donor and recipient patients. The total calculated cost of LDLT is 175, 210.78 Euros. The analysis of the economical obligation that this practice brings is the starting point for an accurate evaluation of all

Aryl C—H···Cl– Hydrogen Bonding in a Fluorescent Anion Sensor

PubMed Central

Tresca, Blakely W.; Zakharov, Lev N.; Carroll, Calden N.; Johnson, Darren W.; Haley, Michael M.

2014-01-01

A new phenyl-acetylene receptor containing a carbonaceous hydrogen bond donor activates anion binding in conjunction with two stabilizing ureas. The unusual CH···Cl– hydrogen bond is apparent in solution by large 1H NMR chemical shifts and by a short, linear contact in the solid state. PMID:23843050

Deceased donor renal transplantation from older donors to increase the donor pool.

PubMed

Kute, Vivek B; Trivedi, Hargovind L; Vanikar, Aruna V; Shah, Pankaj R; Gumber, Manoj R; Patel, Himanshu V; Modi, Pranjal R; Shah, Veena R

2012-09-01

Use of kidneys from donors aged 70 years and older is controversial. Organ shortage has led many transplant centers to accept kidneys from old, suboptimal deceased donors and make increasing use of old-for-old allocation systems. We describe our institutional experience with outcomes from transplanting deceased-donor kidneys from older donors (=70 years). 20 deceased donor renal transplants (DDRTx) were performed at our center using grafts from deceased donors 70 years and older between June 2004 and September 2011. Kidneys were allocated to dual or single grafting according to pre-transplant biopsy. Mean age of recipients was 47.60 ± 11.38 years, 13 of whom were males. Mean donor age was 76.49 ± 4.9 years; 10 of whom were males. The most common cause of donor death was cerebrovascular/road traffic accidents. Mean dialysis duration pre-transplantation was 19.5 ± 6.5 months. Mean HLA (Human Leukocyte Antigens) match was 1 ± 0.8. Most common recipient diseases leading to ESRD were chronic glomerulonephritis (25%), diabetes (20%), and hypertension (20%). Post-transplant immunosuppression consisted of a calcineurin inhibitor-based regimen. Over a mean follow-up of 2.8 ± 1.7 years, patient and graft survival rates were 75% (n = 15) and 80% ( n = 16), respectively, with a mean serum creatinine of 1.78 ± 0.56 mg/dl; 20% of the patients had biopsy-proven acute rejection episodes. A total of 25% (n = 5) patients died, mainly due to infections. DDRTx from older donors achieves acceptable graft function with patient/graft survival, provided that organs are allocated to dual or single grafting according to pre-transplant biopsy. These findings encourage the use of this approach even in low-income countries.

Catalyzed borohydrides for hydrogen storage

DOEpatents

Au, Ming [Augusta, GA

2012-02-28

A hydrogen storage material and process is provided in which alkali borohydride materials are created which contain effective amounts of catalyst(s) which include transition metal oxides, halides, and chlorides of titanium, zirconium, tin, and combinations of the various catalysts. When the catalysts are added to an alkali borodydride such as a lithium borohydride, the initial hydrogen release point of the resulting mixture is substantially lowered. Additionally, the hydrogen storage material may be rehydrided with weight percent values of hydrogen at least about 9 percent.

Hydrogen-bond coordination in organic crystal structures: statistics, predictions and applications.

PubMed

Galek, Peter T A; Chisholm, James A; Pidcock, Elna; Wood, Peter A

2014-02-01

Statistical models to predict the number of hydrogen bonds that might be formed by any donor or acceptor atom in a crystal structure have been derived using organic structures in the Cambridge Structural Database. This hydrogen-bond coordination behaviour has been uniquely defined for more than 70 unique atom types, and has led to the development of a methodology to construct hypothetical hydrogen-bond arrangements. Comparing the constructed hydrogen-bond arrangements with known crystal structures shows promise in the assessment of structural stability, and some initial examples of industrially relevant polymorphs, co-crystals and hydrates are described.

Hydrogenation of coal liquid utilizing a metal carbonyl catalyst

DOEpatents

Feder, Harold M.; Rathke, Jerome W.

1979-01-01

Coal liquid having a dissolved transition metal, catalyst as a carbonyl complex such as Co.sub.2 (CO.sub.8) is hydrogenated with hydrogen gas or a hydrogen donor. A dissociating solvent contacts the coal liquid during hydrogenation to form an immiscible liquid mixture at a high carbon monoxide pressure. The dissociating solvent, e.g. ethylene glycol, is of moderate coordinating ability, while sufficiently polar to solvate the transition metal as a complex cation along with a transition metal, carbonyl anion in solution at a decreased carbon monoxide pressure. The carbon monoxide pressure is reduced and the liquids are separated to recover the hydrogenated coal liquid as product. The dissociating solvent with the catalyst in ionized form is recycled to the hydrogenation step at the elevated carbon monoxide pressure for reforming the catalyst complex within fresh coal liquid.

Mechanistic details for cobalt catalyzed photochemical hydrogen production in aqueous solution: Efficiencies of the photochemical and non-photochemical steps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shan, Bing; Baine, Teera; Ma, Xuan Anh N.

2013-04-17

The use of sunlight to drive chemical reactions that lead to the reduction of water to produce hydrogen is a potential avenue of solar energy utilization. There are many individual steps that take place in this process. This paper reports the investigation of a particular system that involves light absorbing molecules, electron donating agents and a catalyst for water reduction to hydrogen. We evaluated the efficiency of the light induced formation of a strong electron donor, the use of this donor to reduce the catalyst and finally the efficiency of the catalyst to produce hydrogen from water. From this, themore » sources of loss of efficiency could be clearly identified and used in the design of better systems to produce hydrogen from water.« less

The biopsied donor liver: incorporating macrosteatosis into high-risk donor assessment.

PubMed

Spitzer, Austin L; Lao, Oliver B; Dick, André A S; Bakthavatsalam, Ramasamy; Halldorson, Jeffrey B; Yeh, Matthew M; Upton, Melissa P; Reyes, Jorge D; Perkins, James D

2010-07-01

To expand the donor liver pool, ways are sought to better define the limits of marginally transplantable organs. The Donor Risk Index (DRI) lists 7 donor characteristics, together with cold ischemia time and location of the donor, as risk factors for graft failure. We hypothesized that donor hepatic steatosis is an additional independent risk factor. We analyzed the Scientific Registry of Transplant Recipients for all adult liver transplants performed from October 1, 2003, through February 6, 2008, with grafts from deceased donors to identify donor characteristics and procurement logistics parameters predictive of decreased graft survival. A proportional hazard model of donor variables, including percent steatosis from higher-risk donors, was created with graft survival as the primary outcome. Of 21,777 transplants, 5051 donors had percent macrovesicular steatosis recorded on donor liver biopsy. Compared to the 16,726 donors with no recorded liver biopsy, the donors with biopsied livers had a higher DRI, were older and more obese, and a higher percentage died from anoxia or stroke than from head trauma. The donors whose livers were biopsied became our study group. Factors most strongly associated with graft failure at 1 year after transplantation with livers from this high-risk donor group were donor age, donor liver macrovesicular steatosis, cold ischemia time, and donation after cardiac death status. In conclusion, in a high-risk donor group, macrovesicular steatosis is an independent risk factor for graft survival, along with other factors of the DRI including donor age, donor race, donation after cardiac death status, and cold ischemia time.

The change in hydrogen bond strength accompanying charge rearrangement: Implications for enzymatic catalysis

PubMed Central

Shan, Shu-ou; Herschlag, Daniel

1996-01-01

The equilibrium for formation of the intramolecular hydrogen bond (KHB) in a series of substituted salicylate monoanions was investigated as a function of ΔpKa, the difference between the pKa values of the hydrogen bond donor and acceptor, in both water and dimethyl sulfoxide. The dependence of log KHB upon ΔpKa is linear in both solvents, but is steeper in dimethyl sulfoxide (slope = 0.73) than in water (slope = 0.05). Thus, hydrogen bond strength can undergo substantially larger increases in nonaqueous media than aqueous solutions as the charge density on the donor or acceptor atom increases. These results support a general mechanism for enzymatic catalysis, in which hydrogen bonding to a substrate is strengthened as charge rearranges in going from the ground state to the transition state; the strengthening of the hydrogen bond would be greater in a nonaqueous enzymatic active site than in water, thus providing a rate enhancement for an enzymatic reaction relative to the solution reaction. We suggest that binding energy of an enzyme is used to fix the substrate in the low-dielectric active site, where the strengthening of the hydrogen bond in the course of a reaction is increased. PMID:8962076

Evaluation of Potential Donors in Living Donor Liver Transplantation.

PubMed

Dirican, A; Baskiran, A; Dogan, M; Ates, M; Soyer, V; Sarici, B; Ozdemir, F; Polat, Y; Yilmaz, S

2015-06-01

Correct donor selection in living donor liver transplantation (LDLT) is essential not only to decrease the risks of complications for the donors but also to increase the survival of both the graft and the recipient. Knowing their most frequent reasons of donor elimination is so important for transplantation centers to gain time. In this study we evaluated the effectiveness of potential donors in LDLT and studied the reasons for nonmaturation of potential liver donors at our transplantation center. We studied the outcomes of 342 potential living donor candidates for 161 recipient candidates for liver transplantation between January 2013 and June 2014. Donor candidates' gender, age, body mass index (BMI), relationship with recipient, and causes of exclusion were recorded. Among 161 recipients, 96 had a LDLT and 7 had cadaveric liver transplantation. Twelve of the 342 potential donors did not complete their evaluation; 106 of the remaining 330 donor candidates were accepted as suitable for donation (32%) but 10 of these were excluded preoperatively. The main reasons for unsuitability for liver donation were small remnant liver size (43%) and fatty changes of the liver (38.4%). Other reasons were arterial anatomic variations, ABO incompatibility, and Gilbert syndrome. Only 96 of the candidates (29% of the 330 candidates who completed the evaluation) underwent donation. Effective donors were 29% of potential and 90.5% of suitable donors. In our center, 106 of 330 (32%) donor candidates were suitable for donation and the main reasons for unsuitability for liver donation were small remnant liver size and fatty changes of the liver. Copyright © 2015 Elsevier Inc. All rights reserved.

Gamete donors' expectations and experiences of contact with their donor offspring

PubMed Central

Kirkman, Maggie; Bourne, Kate; Fisher, Jane; Johnson, Louise; Hammarberg, Karin

2014-01-01

STUDY QUESTION What are the expectations and experiences of anonymous gamete donors about contact with their donor offspring? SUMMARY ANSWER Rather than consistently wanting to remain distant from their donor offspring, donors' expectations and experiences of contact with donor offspring ranged from none to a close personal relationship. WHAT IS KNOWN ALREADY Donor conception is part of assisted reproduction in many countries, but little is known about its continuing influence on gamete donors' lives. STUDY DESIGN, SIZE, DURATION A qualitative research model appropriate for understanding participants' views was employed; semi-structured interviews were conducted during January–March 2013. PARTICIPANTS/MATERIALS, SETTING, METHODS Before 1998, gamete donors in Victoria, Australia, were subject to evolving legislation that allowed them to remain anonymous or (from 1988) to consent to the release of identifying information. An opportunity to increase knowledge of donors' expectations and experiences of contact with their donor offspring recently arose in Victoria when a recommendation was made to introduce mandatory identification of donors on request from their donor offspring, with retrospective effect. Pre-1998 donors were invited through an advertising campaign to be interviewed about their views, experiences and expectations; 36 sperm donors and 6 egg donors participated. MAIN RESULTS AND THE ROLE OF CHANCE This research is unusual in achieving participation by donors who would not normally identify themselves to researchers or government inquiries. Qualitative thematic analysis revealed that most donors did not characterize themselves as parents of their donor offspring. Donors' expectations and experiences of contact with donor offspring ranged from none to a close personal relationship. LIMITATIONS, REASONS FOR CAUTION It is not possible to establish whether participants were representative of all pre-1998 donors. WIDER IMPLICATIONS OF THE FINDINGS Anonymous

Retention of "safe" blood donors. The Retrovirus Epidemiology Donor Study.

PubMed

Thomson, R A; Bethel, J; Lo, A Y; Ownby, H E; Nass, C C; Williams, A E

1998-04-01

There are obvious advantages to increasing donor retention. However, for reasons of blood safety, certain donors may, in fact, be more desirable to retain than others. "Safe" donors are defined as those who provided a blood donation that was negative on all laboratory screening tests and who subsequently reported no behavioral risks in response to an anonymous survey. This study identifies the most important factors affecting the intention of "safe" donors to provide another donation. An anonymous survey asking about donation history, sexual history, injecting drug use, and recent donation experience was mailed to 50,162 randomly selected allogeneic donors (including directed donors) who gave blood from April through July or from October through December 1993 at one of the five United States blood centers participating in the Retrovirus Epidemiology Donor Study. Before mailing, questionnaires were coded to designate donors with nonreactive laboratory screening tests at their most recent donation. A total of 34,726 donors (69%) responded, with substantially higher response among repeat donors. According to reported intentions only, the vast majority of "safe" donors indicated a high likelihood of donating again within the next 12 months. Only 3.4 percent reported a low likelihood of donating again. A comparison of those likely to return and those unlikely to return reveals significant differences in demographics and in ratings of the donation experience. A higher proportion of those unlikely to return were first-time donors, minority-group donors, and donors with less education. The highest projected loss among "safe" donors was seen for those who gave a fair to poor assessment of their treatment by blood center staff or of their physical well-being during or after donating. These data suggest that efforts to improve donors' perceptions of their donation experience, as well as attention to the physical effects of blood donation, may aid in the retention of both

Which Donor for Uterus Transplants: Brain-Dead Donor or Living Donor? A Systematic Review.

PubMed

Lavoué, Vincent; Vigneau, Cécile; Duros, Solène; Boudjema, Karim; Levêque, Jean; Piver, Pascal; Aubard, Yves; Gauthier, Tristan

2017-02-01

The aim of this systematic review was to evaluate and compare the pros and cons of using living donors or brain-dead donors in uterus transplantation programs, 2 years after the first worldwide live birth after uterus transplantation. The Medline database and the Central Cochrane Library were used to locate uterine transplantation studies carried out in human or nonhuman primates. All types of articles (case reports, original studies, meta-analyses, reviews) in English or French were considered for inclusion. Overall, 92 articles were screened and 44 were retained for review. Proof of concept for human uterine transplantation was demonstrated in 2014 with a living donor. Compared with a brain-dead donor strategy, a living donor strategy offers greater possibilities for planning surgery and also decreases cold ischemia time, potentially translating into a higher success rate. However, this approach poses ethical problems, given that the donor is exposed to surgery risks but does not derive any direct benefit. A brain-dead donor strategy is more acceptable from an ethical viewpoint, but its feasibility is currently unproven, potentially owing to a lack of compatible donors, and is associated with a longer cold ischemia time and a potentially higher rejection rate. The systematic review demonstrates that uterine transplantation is a major surgical innovation for the treatment of absolute uterine factor infertility. Living and brain-dead donor strategies are not mutually exclusive and, in view of the current scarcity of uterine grafts and the anticipated future rise in demand, both will probably be necessary.

Motivations for Giving of Alumni Donors, Lapsed Donors and Non-Donors: Implications for Christian Higher Education

ERIC Educational Resources Information Center

Rugano, Emilio Kariuki

2011-01-01

This descriptive and causal comparative study sought to identify motivations for alumni donor acquisition and retention in Christian institutions of higher learning. To meet this objective, motivations for alumni donors, lapsed donors, and non-donors were analyzed and compared. Data was collected through an electronic survey of a stratified sample…

Methane and Hydrogen Production from Anaerobic Fermentation of Municipal Solid Wastes

NASA Astrophysics Data System (ADS)

Kobayashi, Takuro; Lee, Dong-Yeol; Xu, Kaiqin; Li, Yu-You; Inamori, Yuhei

Methane and hydrogen production was investigated in batch experiments of thermophilic methane and hydrogen fermentation, using domestic garbage and food processing waste classified by fat/carbohydrate balance as a base material. Methane production per unit of VS added was significantly positively correlated with fat content and negatively correlated with carbohydrate content in the substrate, and the average value of the methane production per unit of VS added from fat-rich materials was twice as large as that from carbohydrate-rich materials. By contrast, hydrogen production per unit of VS added was significantly positively correlated with carbohydrate content and negatively correlated with fat content. Principal component analysis using the results obtained in this study enable an evaluation of substrates for methane and hydrogen fermentation based on nutrient composition.

Heterofunctionality interaction with donor solvent coal liquefaction. Final progress report, August 1982-April 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cronauer, D.C.

1984-05-01

This project was undertaken to understand the role of the coal liquefaction solvent through a study of the interaction between the hydrogen donor solvent characteristics and the heterofunctionality of the solvent. Specifically, hydroxyl- and nitrogen-containing solvents were studied and characterized. A series of coal liquefaction experiments were carried out at 450/sup 0/C in a continuous feed stirred-tank reactor (CSTR) to observe the effect of adding phenolics to anthracene oil (AO) and SRC-II recycle solvents. The addition of phenol to AO at a ratio of 5/65 resulted in a nominal increase in coal conversion to THF solubles, but the amount ofmore » asphaltenes more than doubled resulting in a sizable net loss of solvent. The addition of m-cresol to both AO and SRC-II solvents had a positive effect on coal conversion to both THF and pentane solubles (oils). The partial removal of an OH-concentrate from SRC-II solvent was carried out using Amberlyst IRA-904 ion exchange resin. The resin-treated oil was only marginally better than raw SRC-II recycle solvent for coal liquefaction. Hydroaromatics having nitrogen functionality should be good solvents for coal liquefaction considering their effective solvent power, ability to penetrate and swell coal, and their ability to readily transfer hydrogen, particularly in the presence of oxygen functionality. However, these benefits are overshadowed by the strong tendency of the nitrogen-containing species to adduct with themselves and coal-derived materials.« less

Hydrogen sulphide protects against NSAID-enteropathy through modulation of bile and the microbiota

PubMed Central

Blackler, Rory W; Motta, Jean-Paul; Manko, Anna; Workentine, Matthew; Bercik, Premysl; Surette, Michael G; Wallace, John L

2015-01-01

Background and Purpose Hydrogen sulphide is an important mediator of gastrointestinal mucosal defence. The use of non-steroidal anti-inflammatory drugs (NSAIDs) is significantly limited by their toxicity in the gastrointestinal tract. Particularly concerning is the lack of effective preventative or curative treatments for NSAID-induced intestinal damage and bleeding. We evaluated the ability of a hydrogen sulphide donor to protect against NSAID-induced enteropathy. Experimental Approach Intestinal ulceration and bleeding were induced in Wistar rats by oral administration of naproxen. The effects of suppression of endogenous hydrogen sulphide synthesis or administration of a hydrogen sulphide donor (diallyl disulphide) on naproxen-induced enteropathy was examined. Effects of diallyl disulphide on small intestinal inflammation and intestinal microbiota were also assessed. Bile collected after in vivo naproxen and diallyl disulphide administration was evaluated for cytotoxicity in vitro using cultured intestinal epithelial cells. Key Results Suppression of endogenous hydrogen sulphide synthesis by β-cyano-L-alanine exacerbated naproxen-induced enteropathy. Diallyl disulphide co-administration dose-dependently reduced the severity of naproxen-induced small intestinal damage, inflammation and bleeding. Diallyl disulphide administration attenuated naproxen-induced increases in the cytotoxicity of bile on cultured enterocytes, and prevented or reversed naproxen-induced changes in the intestinal microbiota. Conclusions and Implications Hydrogen sulphide protects against NSAID-enteropathy in rats, in part reducing the cytotoxicity of bile and preventing NSAID-induced dysbiosis. PMID:25297699

Donor profiles: demographic factors and their influence on the donor career.

PubMed

Veldhuizen, I J T; Doggen, C J M; Atsma, F; De Kort, W L A M

2009-08-01

Studying the contribution of demographic factors to the donor career provides important knowledge to be used for donor management. The aim of this study is to gain insight into donor characteristics, more specifically into the demographic profile of active vs. resigned donors, and multi-gallon vs. occasional donors. The study population consisted of all registered Dutch whole-blood donors between 1 January 2004 and 1 January 2005 (N = 370 470). The effect of several blood donor characteristics and demographic variables on (i) resigning donating and (ii) being a multi-gallon donor were assessed. Blood donor characteristics were extracted from the blood bank information system and included age, sex, blood group, number of donations and invitations. Demographic characteristics were constituted by population data on urbanization level, socio-economic status (income, housing value), and ethnicity. Men clearly resigned less often than women (odds ratio (OR) 0.73, 95% confidence interval (CI) 0.72-0.75). Being older than 24 years, having a high income, a high-priced house, living in less urbanized areas or areas with relatively few ethnically diverse people also reduced the stopping risk. With respect to multi-gallon donorship, men were five times more often multi-gallon donor than women (OR 5.27, 95% CI 5.15-5.39) irrespective of the number of donation invitations. Furthermore, multi-gallon donors appeared to live in urbanized areas and have a higher income than occasional donors. Our results show that different donor profiles can be distinguished. Differences between active and resigned donors include age, the number of donations, sex, socio-economic-status, ethnicity, and urbanization level. The factors highly associated with being a multi-gallon donor are sex, age, socio-economic status, and to a lesser extent urbanization level. Donor profiles do provide the blood bank with knowledge on their donor population, which may be used as valuable information for donor

Effects of different electron donor feeding patterns on TCE reductive dechlorination performance.

PubMed

Panagiotakis, I; Antoniou, K; Mamais, D; Pantazidou, M

2015-03-01

This study investigates how the feeding pattern of e(-) donors might affect the efficiency of enhanced in situ bioremediation in TCE-contaminated aquifers. A series of lab-scale batch experiments were conducted using butyrate or hydrogen gas (H2) as e(-) donor and a TCE-dechlorinating microbial consortium dominated by Dehalococcoides spp. The results of these experiments demonstrate that butyrate is similarly efficient for TCE dechlorination whether it is injected once or in doses. Moreover, the present work indicates that the addition of butyrate in great excess cannot be avoided, since it most likely provide, even indirectly, significant part of the H2 required. Furthermore, methanogenesis appears to be the major ultimate e(-) accepting process in all experiments, regardless the e(-) donor used and the feeding pattern. Finally, the timing of injection of H2 seems to significantly affect dechlorination performance, since the injection during the early stages improves VC-to-ETH dechlorination and reduce methanogenic activity.

Hydrogen bond dynamics in bulk alcohols.

PubMed

Shinokita, Keisuke; Cunha, Ana V; Jansen, Thomas L C; Pshenichnikov, Maxim S

2015-06-07

Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamics-quantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquid--alcohols--has attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups.

Are drowned donors marginal donors? A single pediatric center experience.

PubMed

Kumm, Kayla R; Galván, N Thao N; Koohmaraie, Sarah; Rana, Abbas; Kueht, Michael; Baugh, Katherine; Hao, Liu; Yoeli, Dor; Cotton, Ronald; O'Mahony, Christine A; Goss, John A

2017-09-01

Drowning, a common cause of death in the pediatric population, is a potentially large donor pool for OLT. Anecdotally, transplant centers have deemed these organs high risk over concerns for infection and graft dysfunction. We theorized drowned donor liver allografts do not portend worse outcomes and therefore should not be excluded from the donation pool. We reviewed our single-center experience of pediatric OLTs between 1988 and 2015 and identified 33 drowned donor recipients. These OLTs were matched 1:2 to head trauma donor OLTs from our center. A chart review assessed postoperative peak AST and ALT, incidence of HAT, graft and recipient survival. Recipient survival at one year between patients with drowned donor vs head trauma donor allografts was not statistically significant (94% vs 97%, P=.63). HAT incidence was 6.1% in the drowned donor group vs 7.6% in the control group (P=.78). Mean postoperative peak AST and ALT was 683 U/L and 450 U/L for drowned donors vs 1119 U/L and 828 U/L in the matched cohort. These results suggest drowned donor liver allografts do not portend worse outcomes in comparison with those procured from head trauma donors. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Two different carbon-hydrogen complexes in silicon with closely spaced energy levels

NASA Astrophysics Data System (ADS)

Stübner, R.; Kolkovsky, Vl.; Weber, J.

2015-08-01

An acceptor and a single donor state of carbon-hydrogen defects (CHA and CHB) are observed by Laplace deep level transient spectroscopy at 90 K. CHA appears directly after hydrogenation by wet chemical etching or hydrogen plasma treatment, whereas CHB can be observed only after a successive annealing under reverse bias at about 320 K. The activation enthalpies of these states are 0.16 eV for CHA and 0.14 eV for CHB. Our results reconcile previous controversial experimental results. We attribute CHA to the configuration where substitutional carbon binds a hydrogen atom on a bond centered position between carbon and the neighboring silicon and CHB to another carbon-hydrogen defect.

Gamete donation: parents' experiences of searching for their child's donor siblings and donor.

PubMed

Freeman, T; Jadva, V; Kramer, W; Golombok, S

2009-03-01

This study investigates the new phenomenon of parents of donor offspring searching for and contacting their child's 'donor siblings' (i.e. donor offspring conceived by the same donor) and donor. Online questionnaires were completed by 791 parents (39% lone-mother, 35% lesbian-couple, 21% heterosexual-couple, 5% non-specified) recruited via the Donor Sibling Registry; a US-based international registry that facilitates contact between donor conception families who share the same donor. Data were collected on parents' reasons for searching for their child's donor siblings and/or donor, the outcome of these searches and parents' and their child's experiences of any resulting contact. Parents' principal motivation for searching for their child's donor siblings was curiosity and for their donor, enhancing their child's sense of identity. Some parents had discovered large numbers of donor siblings (maximum = 55). Most parents reported positive experiences of contacting and meeting their child's donor siblings and donor. This study highlights that having access to information about a child's donor origins is important for some parents and has potentially positive consequences. These findings have wider implications because the removal of donor anonymity in the UK and elsewhere means that increasing numbers of donor offspring are likely to seek contact with their donor relations in the future.

[Personality and donor-recipient relationships of potential donors before living donor liver transplantation--diagnostics with the repertory-grid technique].

PubMed

Walter, Marc; Walter, Otto B; Fliege, Herbert; Klapp, Burghard F; Danzer, Gerhard

2003-06-01

Living-donor liver transplantation (LDLT) is developing into an established therapy for terminal liver diseases in adults. Potential donors are faced with the risk of postoperative complications and are subject to a high level of psychological pressure and ambivalent feelings. Our assumption is that ambivalent feelings before donation are crucially influenced by the personality and the quality of the donor-recipient relationship. In highly motivated donors we expected a positive description of the recipient and a similarity in the characterisation of the donor and recipient. 58 potential living donors were evaluated between March 2000 and June 2001. On the basis of the clinical interview 10 were rated as unsuited for donation. Among those potential donors assessed as unsuited, we found a high level of ambivalent feelings. For 50 potential donors we gained a set of completed psychometric diagnostic questionnaires. A Repertory-grid investigation was conducted with a total of 28 potential donors. Seven of them were not recommended as living donors. The relationship between donors and recipients was analysed concerning constructs that were most important to the characterisation of the donor or recipient. By means of inter-element distances self-concept of donors and donor-recipient relation were analysed. Ambivalent candidates who were not recommended as living donors tended to describe the recipient negatively (selfish, carping, and unable to take criticism) and did not show a similarity in the characterisations of self and ideal-self. Whereas the highly motivated candidates were marked by a closeness of self and ideal-self concepts. Both groups saw the recipient as indifferent. Closeness between self and ideal-self-indicating satisfaction with the decision to donate seems to be one suitable criterion to distinguish between highly motivated potential donors on the one hand and ambivalent candidates on the other hand. Another criterion appears to be a description of

Liver regeneration in donors and adult recipients after living donor liver transplantation.

PubMed

Haga, Junko; Shimazu, Motohide; Wakabayashi, Go; Tanabe, Minoru; Kawachi, Shigeyuki; Fuchimoto, Yasushi; Hoshino, Ken; Morikawa, Yasuhide; Kitajima, Masaki; Kitagawa, Yuko

2008-12-01

In living donor liver transplantation, the safety of the donor operation is the highest priority. The introduction of the right lobe graft was late because of concerns about donor safety. We investigated donor liver regeneration by the types of resected segments as well as recipients to assess that appropriate regeneration was occurring. Eighty-seven donors were classified into 3 groups: left lateral section donors, left lobe donors, and right lobe donors. Forty-seven adult recipients were classified as either left or right lobe grafted recipients. Volumetry was retrospectively performed at 1 week, 1, 2, 3, and 6 months, and 1 year after the operation. In the right lobe donor group, the remnant liver volume was 45.4%, and it rapidly increased to 68.9% at 1 month and 89.8% at 6 months. At 6 months, the regeneration ratios were almost the same in all donor groups. The recipient liver volume increased rapidly until 2 months, exceeding the standard liver volume, and then gradually decreased to 90% of the standard liver volume. Livers of the right lobe donor group regenerated fastest in the donor groups, and the recipient liver regenerated faster than the donor liver. Analyzing liver regeneration many times with a large number of donors enabled us to understand the normal liver regeneration pattern. Although the donor livers did not reach their initial volume, the donors showed normal liver function at 1 year. The donors have returned to their normal daily activities. Donor hepatectomy, even right hepatectomy, can be safely performed with accurate preoperative volumetry and careful decision-making concerning graft-type selection.

Midterm Results of Renal Transplantation From Controlled Cardiac Death Donors Are Similar to Those From Brain Death Donors.

PubMed

Lafuente, O; Sánchez-Sobrino, B; Pérez, M; López-Sánchez, P; Janeiro, D; Rubio, E; Huerta, A; Marques, M; Llópez-Carratala, M R; Rubio, J J; Portolés, J

2016-11-01

The systematic use of grafts from controlled donors after cardiac death (cDCD) started in our country in 2012 and expanded with the strategic support of National Transplant Organization. We present our experience in kidney transplantation with organs from cDCD donors with a mean follow-up of 3 years. Observational prospective study of all transplants performed in our center in 2012-2013 followed to 2016. The immunosuppression protocols were triple therapy for low-risk recipients from a standard brain death donor (DBD), adding basiliximab or thymoglobulin induction for extended-criteria donor or high-risk recipient, respectively, and thymoglobulin induction plus triple therapy for all cDCD recipients. A total of 42 donors were included (84 grafts in total, but 1 discarded due to multiple cysts); 25 DBD and 17 cDCD without differences in age or sex. The graft use rate was 98.9% for cDCD; 55 grafts were implanted in our hospital (26 DBD and 29 cDCD), and the remaining 28 grafts were transferred to other centers. There were no differences in primary failure (3.4% cDCD vs 7.4% DBD), but the cDCD organs had a higher incidence of delayed graft function (51.7% vs 25.9%). Despite that, graft and patient survivals, as well as glomerular filtration rate (66.3 vs 59.6 mL/min) were similar in both groups. Only 1 patient died at home with a functioning graft in the cDCD group. Despite a higher rate of delayed graft function with cDCD, the midterm outcomes are at least similar to those with DBD. The cDCD programs should be promoted to increase the chances of a transplant in our patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of geometry on the pressure induced donor binding energy in semiconductor nanostructures

NASA Astrophysics Data System (ADS)

Kalpana, P.; Jayakumar, K.; Nithiananthi, P.

2015-09-01

The effect of geometry on an on-center hydrogenic donor impurity in a GaAs/(Ga,Al)As quantum wire (QWW) and quantum dot (QD) under the influence of Γ-X band mixing due to an applied hydrostatic pressure is theoretically studied. Numerical calculations are performed in an effective mass approximation. The ground state impurity energy is obtained by variational procedure. Both the effects of pressure and geometry are to exert an additional confinement on the impurity inside the wire as well as dot. We found that the donor binding energy is modified by the geometrical effects as well as by the confining potential when it is subjected to external pressure. The results are presented and discussed.

Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1986-02-01

To make the coal-to-hydrogen route economically attractive, improvements are being sought in each step of the process: coal gasification, water-carbon monoxide shift reaction, and hydrogen separation. This report addresses the use of membranes in the hydrogen separation step. The separation of hydrogen from synthesis gas is a major cost element in the manufacture of hydrogen from coal. Separation by membranes is an attractive, new, and still largely unexplored approach to the problem. Membrane processes are inherently simple and efficient and often have lower capital and operating costs than conventional processes. In this report current ad future trends in hydrogen productionmore » and use are first summarized. Methods of producing hydrogen from coal are then discussed, with particular emphasis on the Texaco entrained flow gasifier and on current methods of separating hydrogen from this gas stream. The potential for membrane separations in the process is then examined. In particular, the use of membranes for H{sub 2}/CO{sub 2}, H{sub 2}/CO, and H{sub 2}/N{sub 2} separations is discussed. 43 refs., 14 figs., 6 tabs.« less

Hydrogen production from salt water by Marine blue green algae and solar radiation

NASA Technical Reports Server (NTRS)

Mitsui, A.; Rosner, D.; Kumazawa, S.; Barciela, S.; Phlips, E.

1985-01-01

Two marine bluegreen algae, Oscillatoria sp. Miami BG 7 and Synechococcus sp Miami 041511 have been selected as the result of over 10 years continuous and intensive effort of isolation, growth examination, and the screening of hydrogen photoproduction capability in this laboratory. Both strains photoproduced hydrogen for several days at high rates and a quantity of hydrogen was accumulated in a closed vessel. Overall hydrogen donor substance of the hydrogen photoproduction was found to be salt water. Using strain Miami BG 7, a two step method of hydrogen photoproduction from salt water was successfully developed and this was recycled several times over a one month period using both free cells and immobilized cells in both indoor and outdoor under natural sunlight. According to these experiments, a prototype floating hydrogen production system was designed for further development of the biosolar hydrogen production system.

Discrete and polymeric self-assembled dendrimers: Hydrogen bond-mediated assembly with high stability and high fidelity

PubMed Central

Corbin, Perry S.; Lawless, Laurence J.; Li, Zhanting; Ma, Yuguo; Witmer, Melissa J.; Zimmerman, Steven C.

2002-01-01

Hydrogen bond-mediated self-assembly is a powerful strategy for creating nanoscale structures. However, little is known about the fidelity of assembly processes that must occur when similar and potentially competing hydrogen-bonding motifs are present. Furthermore, there is a continuing need for new modules and strategies that can amplify the relatively weak strength of a hydrogen bond to give more stable assemblies. Herein we report quantitative complexation studies on a ureidodeazapterin-based module revealing an unprecedented stability for dimers of its self-complementary acceptoracceptor-donor-donor (AADD) array. Linking two such units together with a semirigid spacer that carries a first-, second-, or third-generation Fréchet-type dendron affords a ditopic structure programmed to self assemble. The specific structure that is formed depends both on the size of the dendron and the solvent, but all of the assemblies have exceptionally high stability. The largest discrete nanoscale assembly is a hexamer with a molecular mass of about 17.8 kDa. It is stabilized by 30 hydrogen bonds, including six AADD⋅DDAA contacts. The hexamer forms and is indefinitely stable in the presence of a hexamer containing six ADD⋅DAA hydrogen-bonding arrays. PMID:11917113

A photoluminescence study of the effects of hydrogen on deep levels in MBE grown GaAlAs:Si

NASA Astrophysics Data System (ADS)

Bosacchi, A.; Franchi, S.; Vanzetti, L.; Allegri, P.; Grilli, E.; Guzzi, M.; Zamboni, R.; Pavesi, L.

1991-04-01

We present a study on low-temperature photoluminescence (PL) of Si-doped Ga 1- xAl xAs ( n ~ 1 × 10 17 cm -3, 0.2 ⩽ x ⩽ 0.5) grown by MBE in the presence and in the absence of a hydrogen backpressure, and post-growth hydrogenated or not, by exposure to a hydrogen plasma. The PL spectra of GaAlAs grown without hydrogen are dominated by transitions involving relatively deep donors and/or acceptors independently on whether the material is post-growth hydrogenated. On the contrary, the spectra of GaAlAs grown in the presence of hydrogen are characterized by recombinations related to excitons and/or to shallow donors and acceptors. Both the in-situ and the ex-situ processes result in PL efficiency enhancements, which are definitely larger (by a factor of up to 20) when the former treatment is used. All of the above results suggest that the ex-situ and the in-situ treatments may affect deep levels of different origin, such as DX centers (related to the band structure of the semiconductor) and levels associated to Al-O complexes, respectively.

Experiences of offspring searching for and contacting their donor siblings and donor.

PubMed

Jadva, Vasanti; Freeman, Tabitha; Kramer, Wendy; Golombok, Susan

2010-04-01

This study investigates a new phenomenon whereby individuals conceived by donor insemination are searching for and contacting their donor and/or 'donor siblings' (i.e. donor offspring conceived by the same donor who are their genetic half siblings). On-line questionnaires were completed by members of the Donor Sibling Registry (DSR), a US-based registry that facilitates contact between donor conception families who share the same donor. Of the 165 donor offspring who completed the survey, 15% were searching for their donor siblings, 13% were searching for their donor, and 64% were searching for both. Differences were found according to family type and age of disclosure. Fewer offspring from heterosexual couple families had told their father about their search when compared with offspring from lesbian couple families who had told their co-parent. Offspring who had found out about their conception after age 18 were more likely to be searching for medical reasons, whereas those who had found out before age 18 tended to be searching out of curiosity. Some offspring had discovered large numbers of half siblings (maximum=13). The majority of offspring who had found their donor relations reported positive experiences and remained in regular contact with them. Copyright (c) 2010 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Erythrocyte membrane stability to hydrogen peroxide is decreased in Alzheimer disease.

PubMed

Gilca, Marilena; Lixandru, Daniela; Gaman, Laura; Vîrgolici, Bogdana; Atanasiu, Valeriu; Stoian, Irina

2014-01-01

The brain and erythrocytes have similar susceptibility toward free radicals. Therefore, erythrocyte abnormalities might indicate the progression of the oxidative damage in Alzheimer disease (AD). The aim of this study was to investigate erythrocyte membrane stability and plasma antioxidant status in AD. Fasting blood samples (from 17 patients with AD and 14 healthy controls) were obtained and erythrocyte membrane stability against hydrogen peroxide and 2,2'-azobis-(2-amidinopropane) dihydrochloride (AAPH), serum Trolox equivalent antioxidant capacity (TEAC), residual antioxidant activity or gap (GAP), erythrocyte catalase activity (CAT), erythrocyte superoxide dismutase (SOD) activity, erythrocyte nonproteic thiols, and total plasma thiols were determined. A significant decrease in erythrocyte membrane stability to hydrogen peroxide was found in AD patients when compared with controls (P<0.05). On the contrary, CAT activity (P<0.0001) and total plasma thiols (P<0.05) were increased in patients with AD compared with controls. Our results indicate that the most satisfactory measurement of the oxidative stress level in the blood of patients with AD is the erythrocyte membrane stability to hydrogen peroxide. Reduced erythrocyte membrane stability may be further evaluated as a potential peripheral marker for oxidative damage in AD.

Infected donors in renal transplantation: expanding the donor pool.

PubMed

Outerelo, C; Gouveia, R; Mateus, A; Cruz, P; Oliveira, C; Ramos, A

2013-04-01

The shortage of suitable organ donors is now the most important limiting factor in the field of transplantation and more expanded criteria have been accepted to overcome this problem. The objectives of this study were to evaluate the outcome of patients who received an organ from an infected donor and to compare them with patients who received organs from noninfected donors. Retrospective analysis of all patients who underwent transplantation in our unit between January 2008 and June 2011 was performed. The definition of infected donor included: (1) documented bacteremia at the time of transplantation; and (2) organ-related infection, either with or without isolation from biological products (urine, liquor, and bronchial secretions). Nineteen of 77 transplant recipients (24.7%) received organs from infected donors. There were 9 cases of pneumonia, 4 cases of meningitis with bacteremia, 5 cases of urinary tract infection, 1 case of bacteremia due to Staphylococcus aureus, and 1 case of ventriculo-peritoneal shunt infection. All these recipients were prescribed antibiotic prophylaxis for 10.9 ± 3.2 days, according to the antibiotic administered to the donor. Significant differences between both groups were not observed concerning demographics features, graft thrombosis, arterial disruption, delayed graft function, rejection episodes, and renal graft and patient survivals at 12 months. The recipients of infected donor kidneys were mostly treated with basiliximab for induction therapy. There was a trend toward fewer infectious complications among patients who received organs from infected donors (21.1% vs 44.8%; P = .065) and shorter hospital stay durations (median, 11 vs 17.5 days; P = .041). Kidney transplantation using organs from infected donors did not seem to be associated with a greater risk of complications. Antibiotic therapy initiated in the donor and continued in the recipient may explain these results, perhaps by reducing infectious complications that

Allogeneic blood stem cell transplantation: considerations for donors.

PubMed

Anderlini, P; Körbling, M; Dale, D; Gratwohl, A; Schmitz, N; Stroncek, D; Howe, C; Leitman, S; Horowitz, M; Gluckman, E; Rowley, S; Przepiorka, D; Champlin, R

1997-08-01

Allogeneic transplantation of cytokine-mobilized peripheral blood stem cells (PBSCs) is now being increasingly performed, but safety considerations for hematologically normal PBSC donors have not been fully addressed. Progenitors are generally mobilized for collection from normal donors using recombinant human granulocyte colony-stimulating factor (rhG-CSF). Although the short-term safety profile of rhG-CSF seems acceptable, experience remains limited and its optimal dose and schedule have not been defined. Minimal data exist regarding long-term safety of rhG-CSF, primarily derived from experience in patients with chronic neutropenia or cancer. An "ad hoc" workshop was recently convened among a group of investigators actively involved in the field of allogeneic stem cell transplantation to discuss the safety issues pertaining to normal PBSC donors. There was agreement on the following points: (1) On the basis of available data, it appears that rhG-CSF treatment and PBSC collection have an acceptable short-term safety profile in normal donors. However, the need for continued safety monitoring was recognized. (2) rhG-CSF doses up to 10 microg/kg/d show a consistent dose-response relationship with the mobilization (and collection) of CD34+ progenitor cells, and this dose is acceptable for routine clinical use. Whether higher doses are superior (or cost effective) remains to be determined, and they may produce more severe side effects. The potential risks of marked leukocytosis (arbitrarily defined as a leukocyte count of more than 70 x 10(9)/L) have been a concern, and rhG-CSF dose reduction is performed by many centers to maintain leukocyte counts below this level. (3) Transient post donation cytopenias, involving granulocytes, lymphocytes, and platelets, may occur and are at least partly related to the leukapheresis procedure. These are generally asymptomatic and self-limited; follow-up blood counts are not necessarily required. Reinfusion of autologous platelet

Associations of health status with subsequent blood donor behavior-An alternative perspective on the Healthy Donor Effect from Donor InSight.

PubMed

van den Hurk, Katja; Zalpuri, Saurabh; Prinsze, Femmeke J; Merz, Eva-Maria; de Kort, Wim L A M

2017-01-01

In donor health research, the 'Healthy Donor Effect' (HDE) often biases study results and hampers their interpretation. This refers to the fact that donors are a selected 'healthier' subset of a population due to both donor selection procedures and self-selection. Donors with long versus short donor careers, or with high versus low donation intensities are often compared to avoid this HDE, but underlying health differences might also cause these differences in behaviour. Our aim was to estimate to what extent a donor´s perceived health status associates with donation cessation and intensity. All active whole blood donors participating in Donor InSight (2007-2009; 11,107 male; 12,616 female) were included in this prospective cohort study. We performed Cox survival and Poisson regression analyses to assess whether self-reported health status, medication use, disease diagnosed by a physician and recently having consulted a general practitioner (GP) or specialist were associated with (time to) donation cessation and donation intensity. At the end of 2013, 44% of the donors in this study had stopped donating. Donors in self-rated good health had a 15% lower risk to stop donating compared to donors in perceived poorer health. Medication use, disease diagnoses and consulting a GP were associated with a 20-40% increased risk to stop donating and a lower donation intensity, when adjusting for age, number of donations and new donor status. Both men and women reporting good health made on average 10% more donations. Donors with a "good" health status were less likely to stop donating blood and tended to donate blood more often than donors with perceived poorer health status. This implies that the HDE is an important source of selection bias in studies on donor health and this includes studies where comparisons within donors are made. This HDE should be adjusted for appropriately when assessing health effects of donation and donors' health status may provide estimates of

Feelings of living donors about adult-to-adult living donor liver transplantation.

PubMed

Kusakabe, Tomoko; Irie, Shinji; Ito, Naomi; Kazuma, Keiko

2008-01-01

This study investigated the feelings of living donors about adult-to-adult liver transplantation. We interviewed 18 donors about their feelings before and after transplantation using semistructured interviews and then conducted a content analysis of their responses. Before transplantation, many donors reported that they wanted recipients to live for the donor or his or her family, and there was no one else to donate. Many donors were not anxious, did not feel coerced, and did not consider donation dangerous. Some reported being excited at facing a new experience. Some said they would not mind whatever happens. Others were anxious or unsure about the operation. Diagnostic testing and preoperative blood banking were painful. Donors experienced increasing stress just before the operation. After transplantation, some donors verbalized feeling more grateful to others and that they gained maturity. Throughout the process, donors were concerned about their recipients. Our results suggest that donors might act for themselves or their family. It is important to recognize the varied responses of donors' feelings toward liver transplant recipients.

Outcomes of strategic alternative donor selection or suspending donor search based on Japan Marrow Donor Program coordination status.

PubMed

Kawashima, Naomi; Nishiwaki, Satoshi; Shimizu, Naoko; Kamoshita, Sonoko; Watakabe, Kyoko; Yokohata, Emi; Kurahashi, Shingo; Ozawa, Yukiyasu; Miyamura, Koichi

2018-05-01

In allogeneic hematopoietic stem cell transplantation (allo-HSCT) from unrelated donors, delays in donor search are adversely associated with patient outcome. However, the optimal duration for either waiting for an unrelated donor or selecting alternative sources remains undetermined. Using data from the Japan Marrow Donor Program (JMDP) registry, we retrospectively analyzed 349 adult patients who had searched for unrelated donors. Two hundred and three patients received allo-HSCT from JMDP donors (Group A) with a median of 140 days required to identify a donor, 60 received allo-HSCT from alternative sources (Group B) after a median of 111.5 days at which point either all donor candidates had failed or the patient achieved a second or subsequent complete remission, and 77 suspended allo-HSCT (Group C) after a median of 310 days. The 5-year overall survival (OS) rate in Group A was superior to that of Group C (48.6 vs 38.5%, P = 0.001). Although Group B included more patients with high or very high disease risk index (DRI) at the time of allo-HSCT compared with Group A, the 5-year OS was not significantly different between Groups A and B (48.6 vs 40.9%, P = 0.07), indicating that switching to alternative donors may benefit patients with high DRI.

Reactions of hydrogen with V-Cr-Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiStefano, J.R.; DeVan, J.H.; Chitwood, L.D.

In the absence of increases in oxygen concentration, additions of up to 400 ppm hydrogen to V-4 Cr-4 Ti did not result in significant embrittlement as determined by room temperature tensile tests. However, when hydrogen approached 700 ppm after exposure at 325 C, rapid embrittlement occurred. In this latter case, hydride formation is the presumed embrittlement cause. When oxygen was added during or prior to hydrogen exposure, synergistic effects led to significant embrittlement by 100 ppm hydrogen.

Extended criteria donors in liver transplantation: adapting donor quality and recipient.

PubMed

Gastaca, M

2009-04-01

Despite the progressive increase in the number of liver transplantations, the mortality on the waiting list remains between 5% and 10%, and patients have to deal with longer waiting periods. Facing this situation, transplant centers have developed alternatives to increase the number of grafts by accepting donors who were previously considered to be inadequate, because they are at higher risk of initial poor function and graft failure or may cause disease transmission. Currently, some marginal donors are being routinely used: elderly donors, steatotic grafts, non-heart-beating donors, hepatitis C virus-positive (HCV+) or hepatitis B core antibody-positive donors. These so-called marginal or extended-criteria donors were initially used in high-risk or urgent recipients; however, the number of marginal grafts has significantly increased, forcing the transplant community toward their more rationale use to maintain excellent results of liver transplantation. In this new scenario, the adequacy between donor and recipient may be paramount. Advanced donor age seems to be related to a greater graft failure rate in HCV+ recipients. Early survival seems to be significantly reduced when steatotic grafts are used in recipients with high Model for End-stage Liver Disease (MELD) scores. Moreover, a decreased survival has been observed among high-risk patients receiving organs from marginal donors. No benefit seems to exist when high-donor risk index grafts are transplanted into recipients with low MELD Scores. The recognition of various donor groups according to their quality and the need for good donor and recipient selection must lead us to define new policies for organ allocation of marginal grafts that may come into conflict with current policies of organ allocation according to the risk of death among patients awaiting a liver transplantation.

Travel behavior and deferral of Dutch blood donors: consequences for donor availability.

PubMed

Lieshout-Krikke, Ryanne W; Oei, Welling; Habets, Karin; Pasker-de Jong, Pieternel C M

2015-01-01

Donors returning from areas with outbreaks of infectious diseases may donate infectious blood back home. Geographic donor deferral is an effective measure to ensure the blood safety, but donor deferral may pose a threat for the blood supply especially after holiday seasons. Insight into the travel behavior of blood donors is a first step to define appropriate deferral strategies. This study describes the travel behavior of Dutch donors, the actual deferral, and the consequences of deferral strategies on donor availability. A questionnaire designed to assess travel behavior (destination, frequency, and duration of travels) was sent to 2000 Dutch donors. The impact of travel deferral policies on donor availability was calculated, expressed as proportionate decrease in donor availability. The deferral policies considered were 1) deferral based on entire countries instead of affected regions where an infection is prevalent and 2) deferral after any travel outside Europe ("universal deferral"). Of the 1340 respondents, 790 (58.9%) donors traveled within Europe only, 61 (4.6%) outside Europe only, and 250 (18.7%) within and outside Europe. The deferral for entire countries and universal deferral would lead to 11.1 and 11.4% decrease in donor availability, respectively. Most Dutch donors traveled outside the Netherlands, while 23.2% traveled outside Europe. Universal deferral resulted in an additional decrease in donor availability of 0.3% compared with deferral for entire countries instead of affected regions where an infection is prevalent. Thus, the universal deferral could be considered as a simpler and safer measure. © 2014 AABB.

Redox Control and Hydrogen Production in Sediment Caps Using Carbon Cloth Electrodes

PubMed Central

Sun, Mei; Yan, Fei; Zhang, Ruiling; Reible, Danny D.; Lowry, Gregory V.; Gregory, Kelvin B.

2010-01-01

Sediment caps that degrade contaminants can improve their ability to contain contaminants relative to sand and sorbent-amended caps, but few methods to enhance contaminant degradation in sediment caps are available. The objective of this study was to determine if, carbon electrodes emplaced within a sediment cap at poised potential could create a redox gradient and provide electron donor for the potential degradation of contaminants. In a simulated sediment cap overlying sediment from the Anacostia River (Washington, DC), electrochemically induced redox gradients were developed within 3 days and maintained over the period of the test (~100 days). Hydrogen and oxygen were produced by water electrolysis at the electrode surfaces and may serve as electron donor and acceptor for contaminant degradation. Electrochemical and geochemical factors that may influence hydrogen production were studied. Hydrogen production displayed zero order kinetics with ~75% coulombic efficiency and rates were proportional to the applied potential between 2.5V to 5V and not greatly affected by pH. Hydrogen production was promoted by increasing ionic strength and in the presence of natural organic matter. Graphite electrode-stimulated degradation of tetrachlorobenzene in a batch reactor was dependent on applied voltage and production of hydrogen to a concentration above the threshold for biological dechlorination. These findings suggest that electrochemical reactive capping can potentially be used to create “reactive” sediments caps capable of promoting chemical or biological transformations of contaminants within the cap. PMID:20879761

Utilization of elderly donors in living donor liver transplantation: when more is less?

PubMed

Dayangac, Murat; Taner, C Burcin; Yaprak, Onur; Demirbas, Tolga; Balci, Deniz; Duran, Cihan; Yuzer, Yildiray; Tokat, Yaman

2011-05-01

An accepted definition of donor exclusion criteria has not been established for living donor liver transplantation (LDLT). The use of elderly donors to expand the living donor pool raises ethical concerns about donor safety. The aims of this study were (1) the comparison of the postoperative outcomes of living liver donors by age (≥ 50 versus < 50 years) and (2) the evaluation of the impact of the extent of right hepatectomy on donor outcomes. The study group included 150 donors who underwent donor right hepatectomy between October 2004 and April 2009. Extended criteria surgery (ECS) was defined as right hepatectomy with middle hepatic vein (MHV) harvesting or right hepatectomy resulting in an estimated remnant liver volume (RLV) less than 35%. The primary endpoints were donor outcomes in terms of donor complications graded according to the Clavien classification. Group 1 consisted of donors who were 50 years old or older (n = 28), and group 2 consisted of donors who were less than 50 years old (n = 122). At least 1 ECS criterion was present in 74% of donors: 57% had 1 criterion, and 17% had 2 criteria. None of the donors had grade 4 complications or died. The overall and major complication rates were similar in the 2 donor age groups [28.6% and 14.3% in group 1 and 32% and 8.2% in group 2 for the overall complication rates (P = 0.8) and the major complication rates (P = 0.2), respectively]. However, there was a significant correlation between the rate of major complications and the type of surgery in donors who were 50 years old or older. In LDLT, extending the limits of surgery comes at the price of more complications in elderly donors. Right hepatectomy with MHV harvesting and any procedure causing an RLV less than 35% should be avoided in living liver donors who are 50 years old or older. Copyright © 2011 American Association for the Study of Liver Diseases.

Co-liquefaction of Elbistan Lignite with Manure Biomass; Part 2 - Effect of Biomass Type, Waste to Lignite Ratio and Solid to Liquid Ratio

NASA Astrophysics Data System (ADS)

Karaca, Hüseyin; Koyunoglu, Cemil

2017-12-01

Most coal hydrogenation processes require a large quantity of hydrogen. In general, a coal derived liquid such as anthracene oil was used as a hydrogen donor solvent. Tetralin, partially hydrogenated pyrene, phenantrene and coal-derived solvents, which contain hydroaromatic compounds, are efficient solvents to donate hydrogen. In an attempt to reduce the high cost of hydrogen, part of the hydrogen was replaced by a low cost hydrogen donor solvent. This must be hydrogenated during or before the process and recycled. To reduce the cost of hydrogen donor vehicles instead of liquids recycled from the liquefaction process or several biomass types, industrial by products, liquid fractions derived from oil sands bitumen were successfully used to solubilize a coal from the past. In an attempt to reduce the high cost of hydrogen, part of the hydrogen was replaced by a low cost hydrogen donor solvent. However, when hydrogen is supplied from the hydroaromatic structures present in the solvent, the activity of coal minerals is too low to rehydrogenate the solvent in-situ. Nevertheless, a decrease of using oxygen, in addition to enhanced usage of the hydrogen supply by using various waste materials might lead to a decrease of the cost of the liquefaction procedure. So instead of using tetralin another feeding material such as biomass is becoming another solution improving hydrogen donor substances. Most of the liquefaction process were carried out in a batch reactor, in which the residence time of the liquefaction products is long enough to favour the retrogressive reactions, early studies which are related to liquefaction of coal with biomass generally focus on the synergetic effects of coal while biomass added. Early studies which are related to liquefaction of coal with biomass generally focus on the synergetic effects of coal while biomass added. Alternatively, to understand the hydrogen transfer from biomass to coal, in this study, Elbistan Lignite (EL) with manure, tea

Impurity states and the diamagnetic susceptibility of a donor in a GaAs/AlxGa1-xAs Triangular Quantum Well under hydrostatic pressure

NASA Astrophysics Data System (ADS)

Kalpana, Panneer Selvam; Jayakumar, Kalyanasundaram

2017-11-01

We study the effect of Γ-X band crossover due to the application of hydrostatic pressure of a hydrogenic donor confined in a Triangular GaAs/Al1-xGaxAs Quantum Well (TQW) for x = 0.3 and the diamagnetic susceptibility (χdia) for such an impurity in 1s and some few low lying excited states have been investigated. The Schrodinger equation has been solved using variational technique in the effective mass approximation. The results show that the diamagnetic susceptibility (χdia) of a hydrogenic donor abruptly increases at a particular pressure for 1s and 2p± states but a steady increase for 2s state as a function of applied pressure.

Donor motivation in Xi'an, China: comparison with Canadian donors.

PubMed

O'Brien, S F; Shao, Z-J; Osmond, L; Yi, Q-L; Li, C-Y; An, Q-X

2013-04-01

In China, paid donation is prohibited by law. There is little literature assessing donor motivation in China, and comparison with western countries such as Canada is important in understanding the application of Western literature. We compared motivational factors in donors from the city of Xi'an, China, with Canadian donors matched for age, sex and donation status. A total of 218 donors in Xi'an completed an interview about motivation as did 218 Canadian donors matched for age, sex and donation status. Frequencies and percentages of responses to questions were tabulated and compared using the Chi-squared test. Donors in Xi'an and Canada felt a personal responsibility to donate blood (81·2% vs. 78·0%, P = 0·2057), but Xi'an donors were more likely to consider blood donation a social responsibility (81·7% vs. 45·2%, P < 0·0001). Xi'an donors more often believed that society views donation as a normal activity (98·6% vs. 48·4%, P < 0·0001) and that the social atmosphere promotes donation (90·3% vs. 53·5%, P < 0·0001) and saw greater health benefit (52·3% vs. 12·5%, P < 0·0001). Most Xi'an donors believed in balance between their life force (Qi) and blood (86·7% vs. 49·8%, P < 0·0001) but did not believe blood lost from donating would affect this (0·5% vs. 3·8%, P = 0·01). While traditional Chinese beliefs may not be seen as a barrier among people in Xi'an who donate blood, blood donation is seen differently than by Canadian donors. There is a need for more research specific to China to tailor recruitment strategies. © 2012 The Author(s). Vox Sanguinis © 2012 International Society of Blood Transfusion.

Donor milk volume and characteristics of donors and their children.

PubMed

Sierra-Colomina, Gemma; García-Lara, Nadia Raquel; Escuder-Vieco, Diana; Alonso-Díaz, Clara; Esteban, Eva María Andrés; Pallás-Alonso, Carmen Rosa

2014-05-01

Little is known regarding the effect of the characteristics of donors and their children on the volume of donor milk delivered to a human milk bank (HMB). Our study aimed to determine the relationship between different social and demographic variables of donors and their infants with the volume of human milk delivered. We included donors accepted at the Hospital Doce de Octubre HMB from January 1st, 2009 until April 31st, 2013, and who had finished their donation. Data of social and demographic characteristics of the donors and their children, and the total volume of DHM given were obtained from our HMB database. Included variables were previous donors, donor age, number of children, place of residence, gestational age of the infant at birth, child's age at the start of the donation, hospital admission, and death of the infant. A linear regression model was used to study the relationship between independent variables that were significant in bivariate analysis and the volume of donated milk. A total of 415 donations from 391 women were included. The median volume of milk delivered was 3.1l (IQR-interquartile range-1.3-8.3l). In the linear regression model, previous donors, smaller gestational age of children, and the start of donation at earlier stages of lactation were associated with a larger quantity of HMB donated (p≤0.001). Previous donors, smaller gestational age of children, and the start of donation at earlier stages of lactation are associated with a larger quantity of milk donated to the HMB. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrogen bond strengthening between o-nitroaniline and formaldehyde in electronic excited states: A theoretical study

NASA Astrophysics Data System (ADS)

Yang, Juan; Li, An Yong

2018-06-01

To study the hydrogen bonds upon photoexcited, the time dependent density function method (TD DFT) was performed to investigate the excited state hydrogen bond properties of between o-nitroaniline (ONA) and formaldehyde (CH2O). The optimized structures of the complex and the monomers both in the ground state and the electronically excited states are calculated using DFT and TD DFT method respectively. Quantum chemical calculations of the electronic and vibrational absorption spectra are also carried out by TD DFT method at the different level. The complex ONA⋯CH2O forms the intramolecular hydrogen bond and intermolecular hydrogen bonds. Since the strength of hydrogen bonds can be measured by studying the vibrational absorption spectra of the characteristic groups on the hydrogen bonding acceptor and donor, it evidently confirms that the hydrogen bonds is strengthened in the S1/S2/T1 excited states upon photoexcitation. As a result, the hydrogen bonds cause that the CH stretch frequency of the proton donor CH2O has a blue shift, and the electron excitations leads to a frequency red shift of Ndbnd O and Nsbnd H stretch modes in the o-nitroaniline(ONA) and a small frequency blue shift of CH stretch mode in the formaldehyde(CH2O) in the S1 and S2 excited states. The excited states S1, S2 and T1 are locally excited states where only the ONA moiety is excited, but the CH2O moiety remains in its ground state.

Simulation shows that HLA-matched stem cell donors can remain unidentified in donor searches

PubMed Central

Sauter, Jürgen; Solloch, Ute V.; Giani, Anette S.; Hofmann, Jan A.; Schmidt, Alexander H.

2016-01-01

The heterogeneous nature of HLA information in real-life stem cell donor registries may hamper unrelated donor searches. It is even possible that fully HLA-matched donors with incomplete HLA information are not identified. In our simulation study, we estimated the probability of these unnecessarily failed donor searches. For that purpose, we carried out donor searches in several virtual donor registries. The registries differed by size, composition with respect to HLA typing levels, and genetic diversity. When up to three virtual HLA typing requests were allowed within donor searches, the share of unnecessarily failed donor searches ranged from 1.19% to 4.13%, thus indicating that non-identification of completely HLA-matched stem cell donors is a problem of practical relevance. The following donor registry characteristics were positively correlated with the share of unnecessarily failed donor searches: large registry size, high genetic diversity, and, most strongly correlated, large fraction of registered donors with incomplete HLA typing. Increasing the number of virtual HLA typing requests within donor searches up to ten had a smaller effect. It follows that the problem of donor non-identification can be substantially reduced by complete high-resolution HLA typing of potential donors. PMID:26876789

Simulation shows that HLA-matched stem cell donors can remain unidentified in donor searches

NASA Astrophysics Data System (ADS)

Sauter, Jürgen; Solloch, Ute V.; Giani, Anette S.; Hofmann, Jan A.; Schmidt, Alexander H.

2016-02-01

The heterogeneous nature of HLA information in real-life stem cell donor registries may hamper unrelated donor searches. It is even possible that fully HLA-matched donors with incomplete HLA information are not identified. In our simulation study, we estimated the probability of these unnecessarily failed donor searches. For that purpose, we carried out donor searches in several virtual donor registries. The registries differed by size, composition with respect to HLA typing levels, and genetic diversity. When up to three virtual HLA typing requests were allowed within donor searches, the share of unnecessarily failed donor searches ranged from 1.19% to 4.13%, thus indicating that non-identification of completely HLA-matched stem cell donors is a problem of practical relevance. The following donor registry characteristics were positively correlated with the share of unnecessarily failed donor searches: large registry size, high genetic diversity, and, most strongly correlated, large fraction of registered donors with incomplete HLA typing. Increasing the number of virtual HLA typing requests within donor searches up to ten had a smaller effect. It follows that the problem of donor non-identification can be substantially reduced by complete high-resolution HLA typing of potential donors.

Donor morbidity in right and left hemiliver living donor liver transplantation: the impact of graft selection and surgical innovation on donor safety.

PubMed

Iwasaki, Junji; Iida, Taku; Mizumoto, Masaki; Uemura, Tadahiro; Yagi, Shintaro; Hori, Tomohide; Ogawa, Kohei; Fujimoto, Yasuhiro; Mori, Akira; Kaido, Toshimi; Uemoto, Shinji

2014-11-01

This study investigated adequate liver graft selection for donor safety by comparing postoperative donor liver function and morbidity between the right and left hemilivers (RL and LL, respectively) of living donors. Between April 2006 and March 2012, RL (n = 168) and LL (n = 140) donor operations were performed for liver transplantation at Kyoto University Hospital. Postoperative hyperbilirubinemia and coagulopathy persisted in RL donors, whereas the liver function of LL donors normalized more rapidly. The overall complication rate of the RL donors was significantly higher than that of the LL donors (59.5% vs. 30.7%; P < 0.001). There were no significant differences in severe complications worse than Clavien grade IIIa or in biliary complication rates between the two donor groups. In April 2006, we introduced an innovative surgical procedure: hilar dissection preserving the blood supply to the bile duct during donor hepatectomy. Compared with our previous outcomes (1990-2006), the biliary complication rate of the RL donors decreased from 12.2% to 7.2%, and the severity of these complications was significantly lower. In conclusion, LL donors demonstrated good recovery in postoperative liver function and lower morbidity, and our surgical innovations reduced the severity of biliary complications in living donors. © 2014 Steunstichting ESOT.

Simultaneous effects of temperature and pressure on the donor binding energy in a V-groove quantum wire

NASA Astrophysics Data System (ADS)

Khordad, R.

2010-03-01

The influence of temperature and pressure, simultaneously, on the binding energy of a hydrogenic donor impurity in a ridge GaAs/Ga 1- xAl xAs quantum wire is studied using a variational procedure within the effective mass approximation. The subband energy and the binding energy of the donor impurity in its ground state as a function of the wire bend width and impurity location at different temperatures and pressures are calculated. The results show that, when the temperature increases, the donor binding energy decreases for a constant applied pressure for all wire bend widths. Also, the binding energy increases by increasing the pressure for a constant temperature for all wire bend widths. In addition, when the temperature and pressure are applied simultaneously the binding energy decreases as the quantum wire bend width increases. On the whole, it is deduced that the temperature and pressure have important effects on the donor binding energy in a V-groove quantum wire.

Geobacter sulfurreducens sp. nov., a hydrogen- and acetate-oxidizing dissimilatory metal-reducing microorganism.

PubMed Central

Caccavo, F; Lonergan, D J; Lovley, D R; Davis, M; Stolz, J F; McInerney, M J

1994-01-01

A dissimilatory metal- and sulfur-reducing microorganism was isolated from surface sediments of a hydrocarbon-contaminated ditch in Norman, Okla. The isolate, which was designated strain PCA, was an obligately anaerobic, nonfermentative nonmotile, gram-negative rod. PCA grew in a defined medium with acetate as an electron donor and ferric PPi, ferric oxyhydroxide, ferric citrate, elemental sulfur, Co(III)-EDTA, fumarate, or malate as the sole electron acceptor. PCA also coupled the oxidation of hydrogen to the reduction of Fe(III) but did not reduce Fe(III) with sulfur, glucose, lactate, fumarate, propionate, butyrate, isobutyrate, isovalerate, succinate, yeast extract, phenol, benzoate, ethanol, propanol, or butanol as an electron donor. PCA did not reduce oxygen, Mn(IV), U(VI), nitrate, sulfate, sulfite, or thiosulfate with acetate as the electron donor. Cell suspensions of PCA exhibited dithionite-reduced minus air-oxidized difference spectra which were characteristic of c-type cytochromes. Phylogenetic analysis of the 16S rRNA sequence placed PCA in the delta subgroup of the proteobacteria. Its closest known relative is Geobacter metallireducens. The ability to utilize either hydrogen or acetate as the sole electron donor for Fe(III) reduction makes strain PCA a unique addition to the relatively small group of respiratory metal-reducing microorganisms available in pure culture. A new species name, Geobacter sulfurreducens, is proposed. Images PMID:7527204

Effect of additives on chemoselectivity and diastereoselectivity in the catalytic epoxidation of chiral allylic alcohols with hydrogen peroxide and binuclear manganese complexes.

PubMed

Kilic, Hamdullah; Adam, Waldemar; Alsters, Paul L

2009-02-06

The catalytic oxidations of chiral allylic alcohols 2 by manganese complexes of the cyclic triamine 1,4,7-trimethyl-1,4,7-triazacyclononane (tmtacn) 1 and hydrogen peroxide as oxygen donor in the presence of co-catalyst are investigated to understand the factors that affect the catalyst selectivity. Chemoselectivity and diastereoselectivity of catalyst 1 are significantly affected by the structure of the allylic alcohol and the nature and amount of co-catalyst. More pronounced is the influence of the amount of added molar equivalents of H(2)O(2) (20-110 mol % with respect to the substrate). Our present results reflect the complex redox chemistry of the Mn catalyst 1/H(2)O(2)/co-catalyst system in the early phase of the alkene oxidation.

Donor, dad, or…? Young adults with lesbian parents' experiences with known donors.

PubMed

Goldberg, Abbie E; Allen, Katherine R

2013-06-01

In this exploratory qualitative study of 11 young adults, ages 19-29 years, we examine how young people who were raised by lesbian parents make meaning out of and construct their relationships with known donors. In-depth interviews were conducted to examine how participants defined their family composition, how they perceived the role of their donors in their lives, and how they negotiated their relationships with their donors. Findings indicate that mothers typically chose known donors who were family friends, that the majority of participants always knew who their donors were, and that their contact with donors ranged from minimal to involved. Further, participants perceived their donors in one of three ways: as strictly donors and not members of their family; as extended family members but not as parents; and as fathers. The more limited role of donors in participants' construction of family relationships sheds light on how children raised in lesbian, gay, and bisexual families are contributing to the redefinition and reconstruction of complex kinship arrangements. Our findings hold implications for clinicians who work with lesbian-mother families, and suggest that young adulthood is an important developmental phase during which interest in and contact with the donor may shift, warranting a transfer of responsibility from mother to offspring in terms of managing the donor-child relationship. © FPI, Inc.

High Resolution Structures of the Human ABO(H) Blood Group Enzymes in Complex with Donor Analogs Reveal That the Enzymes Utilize Multiple Donor Conformations to Bind Substrates in a Stepwise Manner*

PubMed Central

Gagnon, Susannah M. L.; Meloncelli, Peter J.; Zheng, Ruixiang B.; Haji-Ghassemi, Omid; Johal, Asha R.; Borisova, Svetlana N.; Lowary, Todd L.; Evans, Stephen V.

2015-01-01

Homologous glycosyltransferases α-(1→3)-N-acetylgalactosaminyltransferase (GTA) and α-(1→3)-galactosyltransferase (GTB) catalyze the final step in ABO(H) blood group A and B antigen synthesis through sugar transfer from activated donor to the H antigen acceptor. These enzymes have a GT-A fold type with characteristic mobile polypeptide loops that cover the active site upon substrate binding and, despite intense investigation, many aspects of substrate specificity and catalysis remain unclear. The structures of GTA, GTB, and their chimeras have been determined to between 1.55 and 1.39 Å resolution in complex with natural donors UDP-Gal, UDP-Glc and, in an attempt to overcome one of the common problems associated with three-dimensional studies, the non-hydrolyzable donor analog UDP-phosphono-galactose (UDP-C-Gal). Whereas the uracil moieties of the donors are observed to maintain a constant location, the sugar moieties lie in four distinct conformations, varying from extended to the “tucked under” conformation associated with catalysis, each stabilized by different hydrogen bonding partners with the enzyme. Further, several structures show clear evidence that the donor sugar is disordered over two of the observed conformations and so provide evidence for stepwise insertion into the active site. Although the natural donors can both assume the tucked under conformation in complex with enzyme, UDP-C-Gal cannot. Whereas UDP-C-Gal was designed to be “isosteric” with natural donor, the small differences in structure imposed by changing the epimeric oxygen atom to carbon appear to render the enzyme incapable of binding the analog in the active conformation and so preclude its use as a substrate mimic in GTA and GTB. PMID:26374898

Investigation of steric influences on hydrogen-bonding motifs in cyclic ureas by using X-ray, neutron, and computational methods.

PubMed

McCormick, Laura J; McDonnell-Worth, Ciaran; Platts, James A; Edwards, Alison J; Turner, David R

2013-11-01

A series of urea-derived heterocycles, 5N-substituted hexahydro-1,3,5-triazin-2-ones, has been prepared and their structures have been determined for the first time. This family of compounds only differ in their substituent at the 5-position (which is derived from the corresponding primary amine), that is, methyl (1), ethyl (2), isopropyl (3), tert-butyl (4), benzyl (5), N,N-(diethyl)ethylamine (6), and 2-hydroxyethyl (7). The common heterocyclic core of these molecules is a cyclic urea, which has the potential to form a hydrogen-bonding tape motif that consists of self-associative R₂²(8) dimers. The results from X-ray crystallography and, where possible, Laue neutron crystallography show that the hydrogen-bonding motifs that are observed and the planarity of the hydrogen bonds appear to depend on the steric hindrance at the α-carbon atom of the N substituent. With the less-hindered substituents, methyl and ethyl, the anticipated tape motif is observed. When additional methyl groups are added onto the α-carbon atom, as in the isopropyl and tert-butyl derivatives, a different 2D hydrogen-bonding motif is observed. Despite the bulkiness of the substituents, the benzyl and N,N-(diethyl)ethylamine derivatives have methylene units at the α-carbon atom and, therefore, display the tape motif. The introduction of a competing hydrogen-bond donor/acceptor in the 2-hydroxyethyl derivative disrupts the tape motif, with a hydroxy group interrupting the N-H···O=C interactions. The geometry around the hydrogen-bearing nitrogen atoms, whether planar or non-planar, has been confirmed for compounds 2 and 5 by using Laue neutron diffraction and rationalized by using computational methods, thus demonstrating that distortion of O-C-N-H torsion angles occurs to maintain almost-linear hydrogen-bonding interactions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen-impurity complexes in III V semiconductors

NASA Astrophysics Data System (ADS)

Ulrici, W.

2004-12-01

This review summarizes the presently available knowledge concerning hydrogen-impurity complexes in III-V compounds. The impurities form shallow acceptors on group III sites (Be, Zn, Cd) and on group V sites (C, Si, Ge) as well as shallow donors on group V sites (S, Se, Te) and on group III sites (Si, Sn). These complexes are mainly revealed by their hydrogen stretching modes. Therefore, nearly all information about their structure and dynamic properties is derived from vibrational spectroscopy. The complexes of shallow impurities with hydrogen have been most extensively investigated in GaAs, GaP and InP. This holds also for Mg-H in GaN. The complexes exhibit a different microscopic structure, which is discussed in detail. The isoelectronic impurity nitrogen, complexed with one hydrogen atom, is investigated in detail in GaAs and GaP. Those complexes can exist in different charge states. The experimental results such as vibrational frequencies, the microscopic structure and the activation energy for reorientation for many of these complexes are in very good agreement with results of ab initio calculations. Different types of oxygen-hydrogen complexes in GaAs and GaP are described, with one hydrogen atom or two hydrogen atoms bonded to oxygen. Three of these complexes in GaAs were found to be electrically active.

Variations of the Hydrogen Bonding and of the Hydrogen Bonded Network in Ethanol-Water Mixtures on Cooling.

PubMed

Pothoczki, Szilvia; Pusztai, Laszlo; Bako, Imre

2018-06-12

Molecular dynamics computer simulations have been conducted for ethanol-water liquid mixtures in the water-rich side of the composition range, with 10, 20 and 30 mol % of the alcohol, at temperatures between room temperature and the experimental freezing point of the given mixture. All-atom type (OPLS) interatomic potentials have been assumed for ethanol, in combination with two kinds of rigid water models (SPC/E and TIP4P/2005). Both combinations have provided excellent reproductions of the experimental X-ray total structure factors at each temperature; this yielded a strong basis for further structural analyses. Beyond partial radial distribution functions, various descriptors of hydrogen bonded assemblies, as well as of the hydrogen bonded network have been determined. A clear tendency was observed towards that an increasing proportion of water molecules participate in hydrogen bonding with exactly 2 donor- and 2 acceptor sites as temperature decreases. Concerning larger assemblies held together by hydrogen bonding, the main focus was put on the properties of cyclic entities: it was found that, similarly to methanol-water mixtures, the number of hydrogen bonded rings has increased with lowering temperature. However, for ethanol-water mixtures the dominance of not the six-, but of the five-fold rings could be observed.

Sperm donor anonymity and compensation: an experiment with American sperm donors

PubMed Central

Cohen, Glenn; Coan, Travis; Ottey, Michelle; Boyd, Christina

2016-01-01

Abstract Most sperm donation that occurs in the USA proceeds through anonymous donation. While some clinics make the identity of the sperm donor available to a donor-conceived child at age 18 as part of ‘open identification’ or ‘identity release programs,’ no US law requires clinics to do so, and the majority of individuals do not use these programs. By contrast, in many parts of the world, there have been significant legislative initiatives requiring that sperm donor identities be made available to children after a certain age (typically when the child turns 18). One major concern with prohibiting anonymous sperm donation has been that the number of willing sperm donors will decrease leading to shortages, as have been experienced in some of the countries that have prohibited sperm donor anonymity. One possible solution, suggested by prior work, would be to pay current anonymous sperm donors more per donation to continue to donate when their anonymity is removed. Using a unique sample of current anonymous and open identity sperm donors from a large sperm bank in the USA, we test that approach. As far as we know, this is the first attempt to examine what would happen if the USA adopted a prohibition on anonymous sperm donation that used the most ecologically valid population, current sperm donors. We find that 29% of current anonymous sperm donors in the sample would refuse to donate if the law changed such that they were required to put their names in a registry available to donor-conceived children at age 18. When we look at the remaining sperm donors who would be willing to participate, we find that they would demand an additional $60 per donation (using our preferred specification). We also discuss the ramifications for the industry. PMID:28852536

Prevalence and estimated incidence of blood-borne viral pathogen infection in organ and tissue donors from northern Alberta.

PubMed

Zahariadis, G; Plitt, S S; O'Brien, S; Yi, Q-L; Fan, W; Preiksaitis, J K

2007-01-01

To determine the potential safety benefit of introducing nucleic acid testing (NAT) in tissue and organ donors, the risk of virus transmission was examined in a Canadian population. Anonymous data on Northern Alberta tissue and organ donors from 1998 to 2004 were used to determine the seroprevalence and estimate the seroincidence and residual risk of HIV, HBV, HCV and HTLV infection. Of the 3372 donors identified, 71.1% were surgical bone, 13.2% were living organ and 15.6% were deceased organ/tissue donors. Seroprevalence was: HIV 0.00%, HBV 0.09%, HCV 0.48% and HTLV 0.03%. Incidence (/100,000 p-yrs) and residual risks (/100,000 donors) could only be estimated for HBV (24.2 and 3.9) and HCV (11.2 and 2.2). Risk estimates were higher for deceased donors than surgical bone donors. HCV had the highest prevalence and HBV had the highest estimated incidence. HIV and HTLV risks were extremely low precluding accurate quantification. In this region of low overall viral prevalence, HCV NAT would be most effective in deceased organ donors. In surgical bone donors the cost of implementing NAT is high without significant added safety benefit.

Hydrogen Production from Nuclear Energy

NASA Astrophysics Data System (ADS)

Walters, Leon; Wade, Dave

2003-07-01

During the past decade the interest in hydrogen as transportation fuel has greatly escalated. This heighten interest is partly related to concerns surrounding local and regional air pollution from the combustion of fossil fuels along with carbon dioxide emissions adding to the enhanced greenhouse effect. More recently there has been a great sensitivity to the vulnerability of our oil supply. Thus, energy security and environmental concerns have driven the interest in hydrogen as the clean and secure alternative to fossil fuels. Remarkable advances in fuel-cell technology have made hydrogen fueled transportation a near-term possibility. However, copious quantities of hydrogen must be generated in a manner independent of fossil fuels if environmental benefits and energy security are to be achieved. The renewable technologies, wind, solar, and geothermal, although important contributors, simply do not comprise the energy density required to deliver enough hydrogen to displace much of the fossil transportation fuels. Nuclear energy is the only primary energy source that can generate enough hydrogen in an energy secure and environmentally benign fashion. Methods of production of hydrogen from nuclear energy, the relative cost of hydrogen, and possible transition schemes to a nuclear-hydrogen economy will be presented.

Donor selection for adult-to-adult living donor liver transplantation: well begun is half done.

PubMed

Sharma, Amit; Ashworth, April; Behnke, Martha; Cotterell, Adrian; Posner, Marc; Fisher, Robert A

2013-02-15

Donor selection criteria for adult-to-adult living donor liver transplantation vary with the medical center of evaluation. Living donor evaluation uses considerable resources, and the nonmaturation of potential into actual donors may sometimes prove fatal for patients with end-stage liver disease. On the contrary, a thorough donor evaluation process is mandatory to ensure safe outcomes in otherwise healthy donors. We aimed to study the reasons for nonmaturation of potential right lobe liver donors at our transplant center. A retrospective data analysis of all potential living liver donors evaluated at our center from 1998 to 2010 was done. Overall, 324 donors were evaluated for 219 potential recipients, and 171 (52.7%) donors were disqualified. Common reasons for donor nonmaturation included the following: (1) donor reluctance, 21%; (2) greater than 10% macro-vesicular steatosis, 16%; (3) assisted donor withdrawal, 14%; (4) inadequate remnant liver volume, 13%; and (5) psychosocial issues, 7%, and thrombophilia, 7%. Ten donors (6%) were turned down because of anatomic variations (8 biliary and 2 arterial anomalies). Donors older than 50 years and those with body mass index of more than 25 were less likely to be accepted for donation. We conclude that donor reluctance, hepatic steatosis, and assisted donor withdrawal are major reasons for nonmaturation of potential into actual donors. Anatomic variations and underlying medical conditions were not a major cause of donor rejection. A system in practice to recognize these factors early in the course of donor evaluation to improve the efficiency of the selection process and ensure donor safety is proposed.

Donor Selection for Adult- to- Adult Living Donor Liver Transplantation: Well Begun is Half Done

PubMed Central

Sharma, Amit; Ashworth, April; Behnke, Martha; Cotterell, Adrian; Posner, Marc; Fisher, Robert A.

2012-01-01

Background Donor selection criteria for adult-to-adult living donor liver transplantation vary with the medical center of evaluation. Living donor evaluation utilizes considerable resources and the non-maturation of potential into actual donors may sometimes prove fatal for patients with end stage liver disease. On the contrary, a thorough donor evaluation process is mandatory to ensure safe outcomes in otherwise healthy donors. We aimed to study the reasons for non-maturation of potential right lobe liver donors at our transplant center. Methods A retrospective data analysis of all potential living liver donors evaluated at our center from 1998 to 2010 was done. Results Overall 324 donors were evaluated for 219 potential recipients and 171 (52.7%) donors were disqualified. Common reasons for donor non-maturation included: (1) Donor reluctance, 21% (2) >10% macro-vesicular steatosis, 16% (3) assisted donor withdrawal, 14% (4) inadequate remnant liver volume, 13% (5) psychosocial issues, 7% and thrombophilia, 7%. Ten donors (6%) were turned down due to anatomical variations (8 biliary and 2 arterial anomalies). Donors older than 50 years and those with BMI over 25 were less likely to be accepted for donation. Conclusions We conclude that donor reluctance, hepatic steatosis and assisted donor withdrawal are major reasons for non-maturation of potential into actual donors. Anatomical variations and underlying medical conditions were not a major cause of donor rejection. A system in practice to recognize these factors early in the course of donor evaluation to improve the efficiency of the selection process and ensure donor safety is proposed. PMID:23128999

Anti-inflammatory and cytoprotective properties of hydrogen sulfide.

PubMed

Gemici, Burcu; Wallace, John L

2015-01-01

Hydrogen sulfide is an endogenous gaseous mediator that plays important roles in many physiological processes in microbes, plants, and animals. This chapter focuses on the important roles of hydrogen sulfide in protecting tissues against injury, promoting the repair of damage, and downregulating the inflammatory responses. The chapter focuses largely, but not exclusively, on these roles of hydrogen sulfide in the gastrointestinal tract. Hydrogen sulfide is produced throughout the gastrointestinal tract, and it contributes to maintenance of mucosal integrity. Suppression of hydrogen sulfide synthesis renders the tissue more susceptible to injury and it impairs repair. In contrast, administration of hydrogen sulfide donors can increase resistance to injury and accelerate repair. Hydrogen sulfide synthesis is rapidly and dramatically enhanced in the gastrointestinal tract after injury is induced. These increases occur specifically at the site of tissue injury. Hydrogen sulfide also plays an important role in promoting resolution of inflammation, and restoration of normal tissue function. In recent years, these beneficial actions of hydrogen sulfide have provided the basis for development of novel hydrogen sulfide-releasing drugs. Nonsteroidal anti-inflammatory drugs that release small amounts of hydrogen sulfide are among the most advanced of the hydrogen sulfide-based drugs. Unlike the parent drugs, these modified drugs do not cause injury in the gastrointestinal tract, and do not interfere with healing of preexisting damage. Because of the increased safety profile of these drugs, they can be used in circumstances in which the toxicity of the parent drug would normally limit their use, such as in chemoprevention of cancer. © 2015 Elsevier Inc. All rights reserved.

Considering Tangible Benefit for Interdependent Donors: Extending a Risk-Benefit Framework in Donor Selection.

PubMed

Van Pilsum Rasmussen, S E; Henderson, M L; Kahn, J; Segev, D

2017-10-01

From its infancy, live donor transplantation has operated within a framework of acceptable risk to donors. Such a framework presumes that risks of living donation are experienced by the donor while all benefits are realized by the recipient, creating an inequitable distribution that demands minimization of donor risk. We suggest that this risk-tolerance framework ignores tangible benefits to the donor. A previously proposed framework more fully considers potential benefits to the donor and argues that risks and benefits must be balanced. We expand on this approach, and posit that donors sharing a household with and/or caring for a potential transplant patient may realize tangible benefits that are absent in a more distantly related donation (e.g. cousin, nondirected). We term these donors, whose well-being is closely tied to their recipient, "interdependent donors." A flexible risk-benefit model that combines risk assessment with benefits to interdependent donors will contribute to donor evaluation and selection that more accurately reflects what is at stake for donors. In so doing, a risk-benefit framework may allow some donors to accept greater risk in donation decisions. © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

Potential of biogenic hydrogen production for hydrogen driven remediation strategies in marine environments.

PubMed

Hosseinkhani, Baharak; Hennebel, Tom; Boon, Nico

2014-09-25

Fermentative production of bio-hydrogen (bio-H2) from organic residues has emerged as a promising alternative for providing the required electron source for hydrogen driven remediation strategies. Unlike the widely used production of H2 by bacteria in fresh water systems, few reports are available regarding the generation of biogenic H2 and optimisation processes in marine systems. The present research aims to optimise the capability of an indigenous marine bacterium for the production of bio-H2 in marine environments and subsequently develop this process for hydrogen driven remediation strategies. Fermentative conversion of organics in marine media to H2 using a marine isolate, Pseudoalteromonas sp. BH11, was determined. A Taguchi design of experimental methodology was employed to evaluate the optimal nutritional composition in batch tests to improve bio-H2 yields. Further optimisation experiments showed that alginate-immobilised bacterial cells were able to produce bio-H2 at the same rate as suspended cells over a period of several weeks. Finally, bio-H2 was used as electron donor to successfully dehalogenate trichloroethylene (TCE) using biogenic palladium nanoparticles as a catalyst. Fermentative production of bio-H2 can be a promising technique for concomitant generation of an electron source for hydrogen driven remediation strategies and treatment of organic residue in marine ecosystems. Copyright © 2014 Elsevier B.V. All rights reserved.

Marginal donors: can older donor hearts tolerate prolonged cold ischemic storage?

PubMed

Korkmaz, Sevil; Bährle-Szabó, Susanne; Loganathan, Sivakkanan; Li, Shiliang; Karck, Matthias; Szabó, Gábor

2013-10-01

Both advanced donor age and prolonged ischemic time are significant risk factors for the 1-year mortality. However, its functional consequences have not been fully evaluated in the early-phase after transplantation; even early graft dysfunction is the main determinant of long-term outcome following transplantation. We evaluated in vivo left-ventricular (LV) cardiac and coronary vascular function of old-donor grafts after short and prolonged cold ischemic times in rats 1 h after heart transplantation. The hearts were excised from young donor (3-month-old) or old donor (18-month-old) rats, stored in cold preservation solution for either 1 or 8 h, and heterotopically transplanted. After 1 h of ischemic period, in the old-donor group, LV pressure, maximum pressure development (dP/dt max), time constant of LV pressure decay (τ), LV end-diastolic pressure and coronary blood flow did not differ compared with young donors. However, endothelium-dependent vasodilatation to acetylcholine resulted in a significantly lower response of coronary blood flow in the old-donor group (33 ± 4 vs. 51 ± 15 %, p < 0.05). After 8 h preservation, two of the old-donor hearts showed no mechanical activity upon reperfusion. LV pressure (55 ± 6 vs. 72 ± 5 mmHg, p < 0.05), dP/dt max (899 ± 221 vs. 1530 ± 217 mmHg/s, p < 0.05), coronary blood flow and response to acetylcholine were significantly reduced and τ was increased in the old-donor group in comparison to young controls. During the early-phase after transplantation, the ischemic tolerance of older-donor hearts is reduced after prolonged preservation time and the endothelium is more vulnerable to ischemia/reperfusion.

Enormous Hydrogen Bond Strength Enhancement through π-Conjugation Gain: Implications for Enzyme Catalysis.

PubMed

Wu, Chia-Hua; Ito, Keigo; Buytendyk, Allyson M; Bowen, K H; Wu, Judy I

2017-08-22

Surprisingly large resonance-assistance effects may explain how some enzymes form extremely short, strong hydrogen bonds to stabilize reactive oxyanion intermediates and facilitate catalysis. Computational models for several enzymic residue-substrate interactions reveal that when a π-conjugated, hydrogen bond donor (XH) forms a hydrogen bond to a charged substrate (Y - ), XH can become significantly more π-electron delocalized, and this "extra" stabilization may boost the [XH···Y - ] hydrogen bond strength by ≥15 kcal/mol. This reciprocal relationship departs from the widespread pK a concept (i.e., the idea that short, strong hydrogen bonds form when the interacting moieties have matching pK a values), which has been the rationale for enzymic acid-base reactions. The findings presented here provide new insight into how short, strong hydrogen bonds could form in enzymes.

Hydrogen Bonding Interaction between Atmospheric Gaseous Amides and Methanol.

PubMed

Zhao, Hailiang; Tang, Shanshan; Xu, Xiang; Du, Lin

2016-12-30

Amides are important atmospheric organic-nitrogen compounds. Hydrogen bonded complexes of methanol (MeOH) with amides (formamide, N -methylformamide, N , N -dimethylformamide, acetamide, N -methylacetamide and N , N -dimethylacetamide) have been investigated. The carbonyl oxygen of the amides behaves as a hydrogen bond acceptor and the NH group of the amides acts as a hydrogen bond donor. The dominant hydrogen bonding interaction occurs between the carbonyl oxygen and the OH group of methanol as well as the interaction between the NH group of amides and the oxygen of methanol. However, the hydrogen bonds between the CH group and the carbonyl oxygen or the oxygen of methanol are also important for the overall stability of the complexes. Comparable red shifts of the C=O, NH- and OH-stretching transitions were found in these MeOH-amide complexes with considerable intensity enhancement. Topological analysis shows that the electron density at the bond critical points of the complexes fall in the range of hydrogen bonding criteria, and the Laplacian of charge density of the O-H∙∙∙O hydrogen bond slightly exceeds the upper value of the Laplacian criteria. The energy decomposition analysis further suggests that the hydrogen bonding interaction energies can be mainly attributed to the electrostatic, exchange and dispersion components.

Hydrogen Bonding Interaction between Atmospheric Gaseous Amides and Methanol

PubMed Central

Zhao, Hailiang; Tang, Shanshan; Xu, Xiang; Du, Lin

2016-01-01

Amides are important atmospheric organic–nitrogen compounds. Hydrogen bonded complexes of methanol (MeOH) with amides (formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide and N,N-dimethylacetamide) have been investigated. The carbonyl oxygen of the amides behaves as a hydrogen bond acceptor and the NH group of the amides acts as a hydrogen bond donor. The dominant hydrogen bonding interaction occurs between the carbonyl oxygen and the OH group of methanol as well as the interaction between the NH group of amides and the oxygen of methanol. However, the hydrogen bonds between the CH group and the carbonyl oxygen or the oxygen of methanol are also important for the overall stability of the complexes. Comparable red shifts of the C=O, NH- and OH-stretching transitions were found in these MeOH–amide complexes with considerable intensity enhancement. Topological analysis shows that the electron density at the bond critical points of the complexes fall in the range of hydrogen bonding criteria, and the Laplacian of charge density of the O–H∙∙∙O hydrogen bond slightly exceeds the upper value of the Laplacian criteria. The energy decomposition analysis further suggests that the hydrogen bonding interaction energies can be mainly attributed to the electrostatic, exchange and dispersion components. PMID:28042825

Donor-transmitted, donor-derived, and de novo cancer after liver transplant.

PubMed

Chapman, Jeremy R; Lynch, Stephen V

2014-03-01

Cancer is the third most common cause of death (after cardiovascular disease and infection) for patients who have a functioning kidney allograft. Kidney and liver transplant recipients have similar cancer risks because of immunosuppression but different risks because of differences in primary diseases that cause renal and hepatic failure and the inherent behavior of cancers in the liver. There are 4 types of cancer that may develop in liver allograft recipients: (1) recurrent cancer, (2) donor-transmitted cancer, (3) donor-derived cancer, and (4) de novo cancer. Identification of potential donor cancer transmission may occur at postmortem examination of a deceased donor or when a probable donor-transmitted cancer is identified in another recipient. Donor-transmitted cancer after liver transplant is rare in Australia, the United Kingdom, and the United States. Aging of the donor pool may increase the risk of subclinical cancer in donors. Liver transplant recipients have a greater risk of de novo cancer than the general population, and risk factors for de novo cancer in liver transplant recipients include primary sclerosing cholangitis, alcoholic liver disease, smoking, and increased age. Liver transplant recipients may benefit from cancer screening because they have a high risk, are clearly identifiable, and are under continuous medical supervision.

Zero risk tolerance costs lives: loss of transplantable organs due to human immunodeficiency virus nucleic acid testing of potential donors.

PubMed

Shafer, Teresa J; Schkade, David; Schkade, Lawrence; Geier, Steven S; Orlowski, Jeffrey P; Klintmalm, Goran

2011-09-01

Patients' deaths due to the organ donor shortage make it imperative that every suitable organ be transplanted. False-positive results of tests for infection with the human immunodeficiency virus (HIV) result in lost organs. A survey of US organ procurement organizations collected the numbers of donors and ruled-out potential donors who had a positive result on an HIV test from January 1,2006, to October 31, 2008. Sixty-two percent of US organ procurement organizations participated. Of the 12397 donor/nondonor cases, 56 (0.45%) had an initial positive result on an HIV antibody or HIV nucleic acid test, and only 8 (14.3%) of those were confirmed positive. Of the false-positive results, 50% were from HIV antibody tests and 50% were from HIV nucleic acid tests. Organs are a scarce, finite, and perishable resource. Use of HIV antibody testing has produced a remarkably safe track record of avoiding HIV transmission, with 22 years of nonoccurrence between transmissions. Because false positives occur with any test, including the HIV Ab test, adding nucleic acid testing to the standard donor testing panel doubles the number of false-positive HIV test results and thus the number of medically suitable donors lost. The required HIV antibody test is 99.99% effective in preventing transmission of the HIV virus. Adding the HIV nucleic acid test to routine organ donor screening could result in as many as 761 to 1551 unnecessary deaths of patients between HIV transmission events because medically suitable organs are wasted.

Marginal kidney donor

PubMed Central

Gopalakrishnan, Ganesh; Gourabathini, Siva Prasad

2007-01-01

Renal transplantation is the treatment of choice for a medically eligible patient with end stage renal disease. The number of renal transplants has increased rapidly over the last two decades. However, the demand for organs has increased even more. This disparity between the availability of organs and waitlisted patients for transplants has forced many transplant centers across the world to use marginal kidneys and donors. We performed a Medline search to establish the current status of marginal kidney donors in the world. Transplant programs using marginal deceased renal grafts is well established. The focus is now on efforts to improve their results. Utilization of non-heart-beating donors is still in a plateau phase and comprises a minor percentage of deceased donations. The main concern is primary non-function of the renal graft apart from legal and ethical issues. Transplants with living donors outnumbered cadaveric transplants at many centers in the last decade. There has been an increased use of marginal living kidney donors with some acceptable medical risks. Our primary concern is the safety of the living donor. There is not enough scientific data available to quantify the risks involved for such donation. The definition of marginal living donor is still not clear and there are no uniform recommendations. The decision must be tailored to each donor who in turn should be actively involved at all levels of the decision-making process. In the current circumstances, our responsibility is very crucial in making decisions for either accepting or rejecting a marginal living donor. PMID:19718332

KSC CENTER DIRECTOR ACCEPTS PLAQUE FOR RECORD-SETTING BONE MARROW DONOR REGISTRATION DRIVE

NASA Technical Reports Server (NTRS)

1996-01-01

Kennedy Space Center's Bone Marrow Donor Registration Drive Chairman Dr. George A. Martin and Center Director Jay Honeycutt (left to right) accept a plaque from the Leukemia Society of America's Associate Executive Director Martin Bernstine and the American Red Cross' Southeast Regional Director Jeff Koenreich. Representatives from the American Red Cross and the Leukemia Society of America came to KSC to honor those involved in the record-setting Bone Marrow Donor Registration Drive held here earlier this year. Over 900 potential donors were added to the National Bone Marrow Registry as a result of the KSC drive. The drive established a new record for the most people registered in a single day for the American Red Cross in the three state region of which Florida is a part.

Safely expanding the donor pool: brain dead donors with history of temporary cardiac arrest.

PubMed

Hoyer, Dieter P; Paul, Andreas; Saner, Fuat; Gallinat, Anja; Mathé, Zoltan; Treckmann, Juergen W; Schulze, Maren; Kaiser, Gernot M; Canbay, Ali; Molmenti, Ernesto; Sotiropoulos, Georgios C

2015-06-01

Cardiac arrest (CA) in deceased organ donors can potentially be associated with ischaemic organ injury, resulting in allograft dysfunction after liver transplantation (LT). The aim of this study was to analyse the influence of cardiac arrest in liver donors. We evaluated 884 consecutive adult patients undergoing LT at our Institution from September 2003 to December 2011. Uni- and multivariable analyses was performed to identify predictive factors of outcome and survival for organs from donors with (CA donor) and without (no CA donor) a history of cardiac arrest. We identified 77 (8.7%) CA donors. Median resuscitation time was 16.5 (1-150) minutes. Allografts from CA donors had prolonged CIT (p = 0.016), were obtained from younger individuals (p < 0.001), and had higher terminal preprocurement AST and ALT (p < 0.001) than those of no CA donors. 3-month, 1-year and 5-year survival for recipients of CA donor grafts was 79%, 76% and 57% and 72.1%, 65.1% and 53% for no CA donor grafts (log rank p = 0.435). Peak AST after LT was significantly lower in CA donor organs than in no CA donor ones (886U/l vs 1321U/l; p = 0.031). Multivariable analysis identified CIT as a risk factor for both patient and graft survival in CA donors. This analysis represents the largest cohort of liver donors with a history of cardiac arrest. Reasonable selection of these donors constitutes a safe approach to the expansion of the donor pool. Rapid allocation and implantation with diminution of CIT may further improve the outcomes of livers from CA donors. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Catalytic transfer hydrogenation for stabilization of bio-oil oxygenates: reduction of p-cresol and furfural over bimetallic Ni-Cu catalysts using isopropanol

USDA-ARS?s Scientific Manuscript database

Transfer hydrogenation and hydrodeoxygenation of model bio-oil compounds (p-cresol and furfural) and bio-oils derived from biomass via traditional pyrolysis and tail-gas reactive pyrolysis (TGRP) were conducted. Mild batch reaction conditions were employed, using isopropanol as a hydrogen donor over...

Two different carbon-hydrogen complexes in silicon with closely spaced energy levels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stübner, R., E-mail: ronald.stuebner@physik.tu-dresden.de, E-mail: kolkov@ifpan.edu.pl; Kolkovsky, Vl., E-mail: ronald.stuebner@physik.tu-dresden.de, E-mail: kolkov@ifpan.edu.pl; Weber, J.

An acceptor and a single donor state of carbon-hydrogen defects (CH{sub A} and CH{sub B}) are observed by Laplace deep level transient spectroscopy at 90 K. CH{sub A} appears directly after hydrogenation by wet chemical etching or hydrogen plasma treatment, whereas CH{sub B} can be observed only after a successive annealing under reverse bias at about 320 K. The activation enthalpies of these states are 0.16 eV for CH{sub A} and 0.14 eV for CH{sub B}. Our results reconcile previous controversial experimental results. We attribute CH{sub A} to the configuration where substitutional carbon binds a hydrogen atom on a bond centered position between carbonmore » and the neighboring silicon and CH{sub B} to another carbon-hydrogen defect.« less

Donor Retention in Online Crowdfunding Communities: A Case Study of DonorsChoose.org

PubMed Central

Althoff, Tim; Leskovec, Jure

2016-01-01

Online crowdfunding platforms like DonorsChoose.org and Kick-starter allow specific projects to get funded by targeted contributions from a large number of people. Critical for the success of crowdfunding communities is recruitment and continued engagement of donors. With donor attrition rates above 70%, a significant challenge for online crowdfunding platforms as well as traditional offline non-profit organizations is the problem of donor retention. We present a large-scale study of millions of donors and donations on DonorsChoose.org, a crowdfunding platform for education projects. Studying an online crowdfunding platform allows for an unprecedented detailed view of how people direct their donations. We explore various factors impacting donor retention which allows us to identify different groups of donors and quantify their propensity to return for subsequent donations. We find that donors are more likely to return if they had a positive interaction with the receiver of the donation. We also show that this includes appropriate and timely recognition of their support as well as detailed communication of their impact. Finally, we discuss how our findings could inform steps to improve donor retention in crowdfunding communities and non-profit organizations. PMID:27077139

Donor Retention in Online Crowdfunding Communities: A Case Study of DonorsChoose.org.

PubMed

Althoff, Tim; Leskovec, Jure

2015-05-01

Online crowdfunding platforms like DonorsChoose.org and Kick-starter allow specific projects to get funded by targeted contributions from a large number of people. Critical for the success of crowdfunding communities is recruitment and continued engagement of donors. With donor attrition rates above 70%, a significant challenge for online crowdfunding platforms as well as traditional offline non-profit organizations is the problem of donor retention. We present a large-scale study of millions of donors and donations on DonorsChoose.org, a crowdfunding platform for education projects. Studying an online crowdfunding platform allows for an unprecedented detailed view of how people direct their donations. We explore various factors impacting donor retention which allows us to identify different groups of donors and quantify their propensity to return for subsequent donations. We find that donors are more likely to return if they had a positive interaction with the receiver of the donation. We also show that this includes appropriate and timely recognition of their support as well as detailed communication of their impact. Finally, we discuss how our findings could inform steps to improve donor retention in crowdfunding communities and non-profit organizations.

Exogenous application of hydrogen sulfide donor sodium hydrosulfide enhanced multiple abiotic stress tolerance in bermudagrass (Cynodon dactylon (L). Pers.).

PubMed

Shi, Haitao; Ye, Tiantian; Chan, Zhulong

2013-10-01

As a gaseous molecule, hydrogen sulfide (H2S) has been recently found to be involved in plant responses to multiple abiotic stress. In this study, salt (150 and 300 mM NaCl), osmotic (15% and 30% PEG6000) and cold (4 °C) stress treatments induced accumulation of endogenous H2S level, indicating that H2S might play a role in bermudagrass responses to salt, osmotic and cold stresses. Exogenous application of H2S donor (sodium hydrosulfide, NaHS) conferred improved salt, osmotic and freezing stress tolerances in bermudagrass, which were evidenced by decreased electrolyte leakage and increased survival rate under stress conditions. Additionally, NaHS treatment alleviated the reactive oxygen species (ROS) burst and cell damage induced by abiotic stress, via modulating metabolisms of several antioxidant enzymes [catalase (CAT), peroxidase (POD) and GR (glutathione reductase)] and non-enzymatic glutathione antioxidant pool and redox state. Moreover, exogenous NaHS treatment led to accumulation of osmolytes (proline, sucrose and soluble total sugars) in stressed bermudagrass plants. Taken together, all these data indicated the protective roles of H2S in bermudagrass responses to salt, osmotic and freezing stresses, via activation of the antioxidant response and osmolyte accumulation. These findings might be applicable to grass and crop engineering to improve abiotic stress tolerance. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Donor solvent coal liquefaction with bottoms recycle at elevated pressure

DOEpatents

Bauman, Richard F.; Taunton, John W.; Anderson, George H.; Trachte, Ken L.; Hsia, Steve J.

1982-01-01

An improved process for liquefying solid carbonaceous materials wherein increased naphtha yields are achieved by effecting the liquefaction at a pressure within the range from about 1750 to about 2800 psig in the presence of recycled bottoms and a hydrogen-donor solvent containing at least 0.8 wt % donatable hydrogen. The liquefaction is accomplished at a temperature within the range from about 700.degree. to about 950.degree. F. The coal:bottoms ratio in the feed to liquefaction will be within the range from about 1:1 to about 5:1 and the solvent or diluent to total solids ratio will be at least 1.5:1 and preferably within the range from about 1.6:1 to about 3:1. The yield of naphtha boiling range materials increases as the pressure increases but generally reaches a maximum at a pressure within the range from about 2000 to about 2500 psig.

Donor Conception and "Passing," or; Why Australian Parents of Donor-Conceived Children Want Donors Who Look Like Them.

PubMed

Wong, Karen-Anne

2017-03-01

This article explores the processes through which Australian recipients select unknown donors for use in assisted reproductive technologies and speculates on how those processes may affect the future life of the donor-conceived person. I will suggest that trust is an integral part of the exchange between donors, recipients, and gamete agencies in donor conception and heavily informs concepts of relatedness, race, ethnicity, kinship, class, and visibility. The decision to be transparent (or not) about a child's genetic parentage affects recipient parents' choices of donor, about who is allowed to "know" children's genetic backgrounds, and how important it is to be able to "pass" as an unassisted conception. In this way, recipients must trust the process, institutions, and individuals involved in their treatment, as well as place trust in the future they imagine for their child. The current market for donor gametes reproduces normative conceptions of the nuclear family, kinship, and relatedness by facilitating "matching" donors to recipients by phenotype and cultural affinities. Recipient parents who choose not to prioritize "matching," and actively disclose the process of children's conceptions, may embark on a project of queering heteronormative family structures and place great trust in both their own children and changing social attitudes to reduce stigma and generate acceptance for non-traditional families.

A simplified donor risk index for predicting outcome after deceased donor kidney transplantation.

PubMed

Watson, Christopher J E; Johnson, Rachel J; Birch, Rhiannon; Collett, Dave; Bradley, J Andrew

2012-02-15

We sought to determine the deceased donor factors associated with outcome after kidney transplantation and to develop a clinically applicable Kidney Donor Risk Index. Data from the UK Transplant Registry on 7620 adult recipients of adult deceased donor kidney transplants between 2000 and 2007 inclusive were analyzed. Donor factors potentially influencing transplant outcome were investigated using Cox regression, adjusting for significant recipient and transplant factors. A United Kingdom Kidney Donor Risk Index was derived from the model and validated. Donor age was the most significant factor predicting poor transplant outcome (hazard ratio for 18-39 and 60+ years relative to 40-59 years was 0.78 and 1.49, respectively, P<0.001). A history of donor hypertension was also associated with increased risk (hazard ratio 1.30, P=0.001), and increased donor body weight, longer hospital stay before death, and use of adrenaline were also significantly associated with poorer outcomes up to 3 years posttransplant. Other donor factors including donation after circulatory death, history of cardiothoracic disease, diabetes history, and terminal creatinine were not significant. A donor risk index based on the five significant donor factors was derived and confirmed to be prognostic of outcome in a validation cohort (concordance statistic 0.62). An index developed in the United States by Rao et al., Transplantation 2009; 88: 231-236, included 15 factors and gave a concordance statistic of 0.63 in the UK context, suggesting that our much simpler model has equivalent predictive ability. A Kidney Donor Risk Index based on five donor variables provides a clinically useful tool that may help with organ allocation and informed consent.

Hydrogenic molecular transitions in double concentric quantum donuts by changing geometrical parameters

NASA Astrophysics Data System (ADS)

Ospina-Londoño, D. A.; Fulla, M. R.; Marín, J. H.

2013-03-01

In this work it is considered a versatile model to study two different ionization processes starting from a D20 homonuclear hydrogenic molecule confined in double concentric quantum donuts. Very narrow quantum donut circular cross sections are considered to separate the radial and angular variables in the D20 Hamiltonian by using the well-known adiabatic approximation D20 total energy as a function of the inter donor spacing and the outer donut center line radius is calculated. The salient features of an artificial D20 hydrogenic molecule such as the dissociation energy and the equilibrium length are strongly dependent on the quantum donut geometrical parameters. By increasing systematically the quantum donut outer center line radius, it is possible to understand a first ionization process: D20→D2++e-. A second ionization process D20→D-+D+ can be carried out by fixing the first donor position and gradually moving away the second one. The results obtained in this study are in good agreement with those previously obtained in the limiting cases of very large inter donor separation. The model proposed here is computationally economical and provides a realistic description of both ionization processes and the few-particle system confined in double concentric quantum donuts.

Fac and mer isomers of Ru(II) tris(pyrazolyl-pyridine) complexes as models for the vertices of coordination cages: structural characterisation and hydrogen-bonding characteristics.

PubMed

Metherell, Alexander J; Cullen, William; Stephenson, Andrew; Hunter, Christopher A; Ward, Michael D

2014-01-07

We have prepared a series of mononuclear fac and mer isomers of Ru(II) complexes containing chelating pyrazolyl-pyridine ligands, to examine their differing ability to act as hydrogen-bond donors in MeCN. This was prompted by our earlier observation that octanuclear cube-like coordination cages that contain these types of metal vertex can bind guests such as isoquinoline-N-oxide (K = 2100 M(-1) in MeCN), with a significant contribution to binding being a hydrogen-bonding interaction between the electron-rich atom of the guest and a hydrogen-bond donor site on the internal surface of the cage formed by a convergent set of CH2 protons close to a 2+ metal centre. Starting with [Ru(L(H))3](2+) [L(H) = 3-(2-pyridyl)-1H-pyrazole] the geometric isomers were separated by virtue of the fact that the fac isomer forms a Cu(I) adduct which the mer isomer does not. Alkylation of the pyrazolyl NH group with methyl iodide or benzyl bromide afforded [Ru(L(Me))3](2+) and [Ru(L(bz))3](2+) respectively, each as their fac and mer isomers; all were structurally characterised. In the fac isomers the convergent group of pendant -CH2R or -CH3 protons defines a hydrogen-bond donor pocket; in the mer isomer these protons do not converge and any hydrogen-bonding involving these protons is expected to be weaker. For both [Ru(L(Me))3](2+) and [Ru(L(bz))3](2+), NMR titrations with isoquinoline-N-oxide in MeCN revealed weak 1 : 1 binding (K ≈ 1 M(-1)) between the guest and the fac isomer of the complex that was absent with the mer isomer, confirming a difference in the hydrogen-bond donor capabilities of these complexes associated with their differing geometries. The weak binding compared to the cage however occurs because of competition from the anions, which are free to form ion-pairs with the mononuclear complex cations in a way that does not happen in the cage complexes. We conclude that (i) the presence of fac tris-chelate sites in the cage to act as hydrogen-bond donors, and (ii

Factors influencing donor return.

PubMed

Schlumpf, Karen S; Glynn, Simone A; Schreiber, George B; Wright, David J; Randolph Steele, Whitney; Tu, Yongling; Hermansen, Sigurd; Higgins, Martha J; Garratty, George; Murphy, Edward L

2008-02-01

To predict future blood donation behavior and improve donor retention, it is important to understand the determinants of donor return. A self-administered questionnaire was completed in 2003 by 7905 current donors. With data mining methods, all factors measured by the survey were ranked as possible predictors of actual return within 12 months. Significant factors were analyzed with logistic regression to determine predictors of intention and of actual return. Younger and minority donors were less likely to return in 12 months. Predictors of donor return were higher prior donation frequency, higher intention to return, a convenient place to donate, and having a good donation experience. Most factors associated with actual donor return were also associated with a high intention to return. Although not significant for actual return, feeling a responsibility to help others, higher empathetic concern, and a feeling that being a blood donor means more than just donating blood were related to high intention to return. Prior donation frequency, intention to return, donation experience, and having a convenient location appear to significantly predict donor return. Clearly, donor behavior is dependent on more than one factor alone. Altruistic behavior, empathy, and social responsibility items did not enter our model to predict actual return. A donor's stated intention to give again is positively related to actual return and, while not a perfect measure, might be a useful proxy when donor return cannot be determined.

Quantum mechanics models of the methanol dimer: OH⋯O hydrogen bonds of β-d-glucose moieties from crystallographic data.

PubMed

Cintrón, Michael Santiago; Johnson, Glenn P; French, Alfred D

2017-04-18

The interaction of two methanol molecules, simplified models of carbohydrates and cellulose, was examined using a variety of quantum mechanics (QM) levels of theory. Energy plots for hydrogen bonding distance (H⋯O) and angle (OH⋯O) were constructed. All but two experimental structures were located in stabilized areas on the vacuum phase energy plots. Each of the 399 models was analyzed with Bader's atoms-in-molecules (AIM) theory, which showed a widespread ability by the dimer models to form OH⋯O hydrogen bonds that have bond paths and Bond Critical Points. Continuum solvation calculations suggest that a portion of the energy-stabilized structures could occur in the presence of water. A survey of the Cambridge Structural Database (CSD) for all donor-acceptor interactions in β-D-glucose moieties examined the similarities and differences among the hydroxyl groups and acetal oxygen atoms that participate in hydrogen bonds. Comparable behavior was observed for the O2H, O3H, O4H, and O6H hydroxyls, acting either as acceptors or donors. Ring O atoms showed distinct hydrogen bonding behavior that favored mid-length hydrogen bonds. Published by Elsevier Ltd.

Family, friends, and faith: how organ donor families heal.

PubMed

Stouder, Donald B; Schmid, Adam; Ross, Sharon S; Ross, Larry G; Stocks, Lisa

2009-12-01

Understanding how organ donors' families recover from their grief can help organ procurement organizations improve consent rates and increase the number of deceased donor organs available for transplant. To determine what helps the loved ones of deceased organ donors heal from their grief and loss, and to better understand families' needs during the consent process as a way of improving overall consent rates for organ donation. Written survey of all organ and tissue donors' families in the San Diego and Imperial County (California) service area during 2006 and 2007. Responses to the 20-question survey addressing factors that help healing from grief, as well as contextual information about the families' experience at the hospital and the consent process. Most respondents (84%) indicated that family support was the most helpful thing in dealing with their grief, followed by the support of friends (74%) and religious and cultural beliefs (37%). Most (75%) indicated that they agreed to donation so that something positive could result from their loss. Most respondents (93%) felt that they were given enough information to make an informed decision about donation, and 6% indicated that the donation process interfered with funeral or memorial arrangements. More than 95% understood that their loved one had died before they were approached for consent. Consistent with previous studies, 12% said they still had unanswered questions about aspects of donation, and 15% of respondents indicated that the discussion about organ donation added more emotional stress to their overall experience.

Multiple hydrogen-bonded complexes based on 2-ureido-4[1H]-pyrimidinone: a theoretical study.

PubMed

Sun, Hao; Lee, Hui Hui; Blakey, Idriss; Dargaville, Bronwin; Chirila, Traian V; Whittaker, Andrew K; Smith, Sean C

2011-09-29

In the present work, the electronic structures and properties of a series of 2-ureido-4[1H]-pyrimidinone(UPy)-based monomers and dimers in various environments (vacuum, chloroform, and water) are studied by density functional theoretical methods. Most dimers prefer to form a DDAA-AADD (D, H-bond donor; A, H-bond acceptor) array in both vacuum and solvents. Topological analysis proved that intramolecular and intermolecular hydrogen bonds coexist in the dimers. Frequency and NBO calculations show that all the hydrogen bonds exhibit an obvious red shift in their stretching vibrational frequencies. Larger substituents at position 6 of the pyrimidinone ring with stronger electron-donating ability favor the total binding energy and free energy of dimerization. Calculations on the solvent effect show that dimerization is discouraged by the stronger polarity of the solvent. Further computations show that Dimer-1 may be formed in chloroform, but water molecules may interact with the donor or acceptor sites and hence disrupt the hydrogen bonds of Dimer-1. © 2011 American Chemical Society

Physiological function of hydrogen metabolism during growth of sulfidogenic bacteria on organic substrates.

PubMed Central

Lupton, F S; Conrad, R; Zeikus, J G

1984-01-01

Desulfovibrio vulgaris Madison and Thermodesulfobacterium commune contained functionally distinct hydrogenase activities, one which exchanged 3H2 into 3H2O and was inhibited by carbon monoxide and a second activity which produced H2 in the presence of CO. Cell suspensions of D. vulgaris used either lactate, pyruvate, or CO as the electron donor for H2 production in the absence of sulfate. Both sulfidogenic species produced and consumed hydrogen as a trace gas during growth on lactate or pyruvate as electron donors and on thiosulfate or sulfate as electron acceptors. Higher initial levels of hydrogen were detected during growth on lactate-sulfate than on pyruvate-sulfate. D. vulgaris but not T. commune also produced and then consumed CO during growth on organic electron donors and sulfate or thiosulfate. High partial pressures of exogenous H2 inhibited growth and substrate consumption when D. vulgaris was cultured on pyruvate alone but not when it was metabolizing pyruvate plus sulfate or lactate plus sulfate. The data are discussed in relation to supporting two different models for the physiological function of H2 metabolism during growth of sulfidogenic bacteria on organic electron donors plus sulfate. A trace H2 transformation model is proposed for control of redox processes during growth on either pyruvate or lactate plus sulfate, and an obligate H2 cycling model is proposed for chemiosmotic energy coupling during growth on CO plus sulfate. PMID:6480553

Microbial utilization of electrically reduced neutral red as the sole electron donor for growth and metabolite production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, D.H.; Laivenieks, M.; Guettler, M.V.

1999-07-01

Electrically reduced neutral red (NR) served as the sole source of reducing power for growth and metabolism of pure and mixed cultures of H[sub 2]-consuming bacteria in a novel electrochemical bioreactor system. NR was continuously reduced by the cathodic potential ([minus]1.5 V) generated from an electric current (0.3 to 1.0 mA), and it was subsequently oxidized by Actinobacillus succinogenes or by mixed methanogenic cultures. The A. succinogenes mutant strain FZ-6 did not grow on fumarate alone unless electrically reduced NR or hydrogen was present as the electron donor for succinate production. The mutant strain, unlike the wild type, lacked pyruvatemore » formate lyase and formate dehydrogenase. Electrically reduced NR also replaced hydrogen as the sole electron donor source for growth and production of methane from CO[sub 2]. These results show that both pure and mixed cultures can function as electrochemical devices when electrically generated reducing power can be used to drive metabolism. The potential utility of utilizing electrical reducing power in enhancing industrial fermentations or biotransformation processes is discussed.« less

Molecular mechanism of gelation with ethylene glycol added to a solution of polyacrylonitrile in dimethylsulfoxide

NASA Astrophysics Data System (ADS)

Vettegren', V. I.; Machalaba, N. N.; Zharov, V. B.; Kulik, V. B.; Savitskii, A. V.

2011-06-01

The mechanism of solidifying a solution of polyacrylonitrile (PAN) in dimethylsulfoxide (DMSO) into which ethylene glycol is added is studied by the method of Raman spectroscopy. In the absence of ethylene glycol, DMSO molecules produce dipole-dipole bonds to PAN molecules. Upon adding ethylene glycol, DMSO molecules form hydrogen bonds with it and a line at 1000 cm-1 appears in the Raman spectrum, which is assigned to the valence vibrations of S=O bonds involved in the hydrogen bonds. After DMSO is removed, ethylene glycol molecules produce hydrogen bonds with two neighboring PAN molecules, giving rise to a band at 2264 cm-1, which is assigned to the valence vibrations of C≡N bonds involved in these hydrogen bonds. A high-viscosity gel consisting of PAN molecules arises in which these molecules are bonded to each other through ethylene glycol molecules.

[Blood donor hemovigilance: impact for donor and recipient safety].

PubMed

Hauser, L; Beyloune, A; Simonet, M; Bierling, P

2013-05-01

Since its creation in 1993, hemovigilance has an important place for blood safety. The part concerning donors, as the name suggests, targeted on improvement of donor's safety covers in fact the two points of the transfusion chain with serious adverse events in donor, epidemiologic survey for recipients and post-donation information on the two sides. Organized management and close collaboration between the actors of the transfusion chain are necessary to ensure the effectiveness of the system. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Quality of life of liver donors following donor hepatectomy.

PubMed

Chandran, Biju; Bharathan, Viju Kumar; Shaji Mathew, Johns; Amma, Binoj Sivasankara Pillai Thankamony; Gopalakrishnan, Unnikrishnan; Balakrishnan, Dinesh; Menon, Ramachandran Narayana; Dhar, Puneet; Vayoth, Sudheer Othiyil; Surendran, Sudhindran

2017-03-01

Although morbidity following living liver donation is well characterized, there is sparse data regarding health-related quality of life (HRQOL) of donors. HRQOL of 200 consecutive live liver donors from 2011-2014 performed at an Indian center were prospectively collected using the SF-36 version 2, 1 year after surgery. The effect of donor demographics, operative details, post-operative complications (Clavien-Dindo and 50-50 criteria), and recipient mortality on the quality-of-life (QOL) scoring was analyzed. Among 200 donors (female/male=141:59), 77 (38.5%) had complications (14.5%, 16.5%, 4.5%, and 3.5%, Clavien-Dindo grades I-IV, respectively). The physical composite score (PCS) of donors 1 year after surgery was less than ideal (48.75±9.5) while the mental composite score (MCS) was good (53.37±6.16). Recipient death was the only factor that showed a statistically significant correlation with both PCS (p<0.001) and MCS (p=0.05). Age above 50 years (p<0.001), increasing body mass index (BMI) (p=0.026), and hospital stay more than 14 days ( p= 0.042) negatively affected the physical scores while emergency surgery (p<0.001) resulted in lower mental scores. Gender, postoperative complications, type of graft, or fulfillment of 50-50 criteria did not influence HRQOL. On asking the hypothetical question whether the donors would be willing to donate again, 99% reiterated there will be no change in their decision. Recipient death, donation in emergency setting, age above 50, higher BMI, and prolonged hospital stay are factors that lead to impaired HRQOL following live liver donation. Despite this, 99% donors did not repent the decision to donate.

Never Declared Brain Dead Potential Organ Donors-An Additional Source of Donor Organs?

PubMed

Webster, Patricia A; Markham, Lori E

2018-03-01

Patients never declared brain dead may represent an additional source of donor organs. To determine the number of likely brain dead potential donors who are never declared brain dead and to compare them with brain dead and donation after cardiac death potential organ donors. This study was a retrospective chart review of all catastrophically brain-injured patients referred to a single-organ procurement organization (OPO) over a 4-year period. This study identified 159 likely brain dead potential organ donors, 902 brain dead potential organ donors, and 357 potential donation after circulatory death donors over a 4-year period. None. This study did not predetermine outcome measures before data collection because the study group, likely brain dead potential organ donors, had not previously been described. Likely brain dead potential donors were significantly older than brain dead potential donors ( P < .0001) but were otherwise not different demographically. They were more likely to be a late referral to the OPO ( P < .0001) and less likely to be in the donor registry ( P < .0001). The most commonly identified factors associated with a failure to declare brain death were an unwillingness to continue supportive care by the family, premention of donation, a nontimely imminent death referral, known prior objection to donation, terminal instability, and a lack of cooperation with the OPO.

Rational Design of Porous Conjugated Polymers and Roles of Residual Palladium for Photocatalytic Hydrogen Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Lianwei; Cai, Zhengxu; Wu, Qinghe

Developing high efficient photocatalyts for splitting water into oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this paper, we report our effort in rationally designing conjugated porous polymer (CPP) photocatalysts for photocatalytic hydrogen production (PHP) from water. A series of CPP photocatalysts with different chromophore components and bipyridyl (bpy) contents were synthesized and found to evolve hydrogen photocatalytically from water. The PHP activity of bpy-containing CPPs can be greatly enhanced due to the improved light absorption, better wettability, higher crystallinity and the improved charge separation process. Moreover, the CPP photocatalyst made of strongmore » and fully conjugated donor chromo-phore DBD shows the highest hydrogen production rate ~ 33 μmol/h. The results indicate that copolymerization between a strong donor and weak acceptor is a useful strategy for the devel-opment of efficient photocatalysts. This study clarifies that the residual palladium in the CPP networks plays a key role for the catalytic performance. The PHP activity of CPP photocatalyst can be further enhanced to 164 μmol/h with an apparent quantum yield of 1.8% at 350 nm by loading 2 wt% of extra platinum cocat-alyst.« less

Assessing the Feasibility of DNAPL Source Zone Remediation: Review of Case Studies

DTIC Science & Technology

2004-05-01

such as sugars, alcohols, fatty acids that are fermented to hydrogen and used for reductive dechlorination) are more soluble than the chlorinated...addition because a greater percentage of the hydrogen produced during the fermentation of added electron donors is consumed by dechlorinating...Battelle, 2002; Stegemeier and Vinegar , 2001; Roote, 2003; USEPA, 1999): i) increasing vapor pressure and volatilization rates of low boiling point

Influence of kinship on donors' mental burden in living donor liver transplantation.

PubMed

Erim, Yesim; Beckmann, Mingo; Kroencke, Sylvia; Sotiropoulos, Georgios C; Paul, Andreas; Senf, Wolfgang; Schulz, Karl-Heinz

2012-08-01

In the context of living donor liver transplantation (LDLT), German transplantation law stipulates that donor candidates should primarily be relatives of the recipients or persons with distinct and close relationships. In this study, we investigated the influence of the relationship between the donor and the recipient on the donor's emotional strain before transplantation. Donors were categorized according to the following subgroups: (1) parents donating for their children, (2) children donating for their parents, (3) siblings, (4) spouses, (5) other relatives, and (6) nonrelatives. The sample consisted of 168 donor candidates. Anxiety (F = 2.8, P = 0.02), depression (F = 2.6, P = 0.03), and emotional quality of life (F = 3.1, P = 0.01) differed significantly according to the relationship between the donor and the recipient. In comparison with healthy controls, parents donating for their children were significantly less stressed before LDLT and demonstrated fewer anxiety (P < 0.01) and depression symptoms (P < 0.05). Adult children donating for their parents demonstrated the highest mental burden and the lowest emotional quality of life. However, this was not due to the responsibility of these children for their own families because differences between donors with children and donors without children could not be ascertained. This group should be given special attention before LDLT and during follow-up visits, and psychological help should be provided when it is necessary. Copyright © 2012 American Association for the Study of Liver Diseases.

Socioeconomic status and ethnicity of deceased donor kidney recipients compared to their donors.

PubMed

Adler, J T; Hyder, J A; Elias, N; Nguyen, L L; Markmann, J F; Delmonico, F L; Yeh, H

2015-04-01

Public perception and misperceptions of socioeconomic disparities affect the willingness to donate organs. To improve our understanding of the flow of deceased donor kidneys, we analyzed socioeconomic status (SES) and racial/ethnic gradients between donors and recipients. In a retrospective cohort study, traditional demographic and socioeconomic factors, as well as an SES index, were compared in 56,697 deceased kidney donor and recipient pairs transplanted between 2007 and 2012. Kidneys were more likely to be transplanted in recipients of the same racial/ethnic group as the donor (p < 0.001). Kidneys tended to go to recipients of lower SES index (50.5% of the time, p < 0.001), a relationship that remained after adjusting for other available markers of donor organ quality and SES (p < 0.001). Deceased donor kidneys do not appear to be transplanted from donors of lower SES to recipients of higher SES; this information may be useful in counseling potential donors and their families regarding the distribution of their organ gifts. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

Gettering of donor impurities by V in GaAs and the growth of semi-insulating crystals

NASA Technical Reports Server (NTRS)

Ko, K. Y.; Lagowski, J.; Gatos, H. C.

1989-01-01

Vanadium added to the GaAs melt getters shallow donor impurities (Si and S) and decreases their concentration in the grown crystals. This gettering is driven by chemical reactions in the melt rather than in the solid. Employing V gettering, reproducibly semi-insulating GaAs were grown by horizontal Bridgman and liquid-encapsulated Czochralski techniques, although V did not introduce any midgap energy levels. The compensation mechanism in these crystals was controlled by the balance between the native midgap donor EL2 and residual shallow acceptors. Vanadium gettering contributed to the reduction of the concentration of shallow donors below the concentration of acceptors. The present findings clarify the long-standing controversy on the role of V in achieving semi-insulating GaAs.

[Search for non-relative donor by the Russian register of bone marrow donors].

PubMed

Zaretskaia, Iu M; Khamaganova, E G; Aleshchenko, S M; Murashova, L A

2002-01-01

To select maximally HLA compatible donor for hematological patients who need transplantation of bone marrow from non-relative donor. 75 patients with hematological malignancy were observed. All of them have indications to non-relative transplantation of the bone marrow. Methods of polymerase chain reaction with sequence-specific primers and classic microlymphocytotoxic test were used. Typing of HLA antigens of class I and alleles of class II loci enabled search for non-relative donor for transplantation of bone marrow in accordance with the requirements of the European Federation of Immunogenetics. Most of the patients (86.6%) had at least one potential HLA-A, -B, -DR compatible donor. Half of the patients had potential donors typed at the allele level by class II loci. This diminishes time of HLA compatible donor selection. DNA typing enables the search for the non-relative donors meeting modern requirements. This allowed 5 non-relative bone marrow transplantations.

Correlation between donor age and organs transplanted per donor: our experience in Japan.

PubMed

Ashikari, J; Omiya, K; Konaka, S; Nomoto, K

2014-05-01

The shortage of available organs for transplantation is a worldwide issue. To maximize the number of transplantations, increasing the number of organs transplanted per donor (OTPD) is widely recognized as an important factor for improving the shortage. In Japan, we have had 211 donors, 1112 organs transplanted, and 924 recipients receiving the transplants, resulting in 4.4 ± 1.4 recipients receiving transplants per donor and 5.3 ± 1.6 OTPD as of February 2013. Because donor age is a well-recognized factor of donor suitability, we analyzed the correlation between donor age group and OTPD. Only the age group 60 to 69 years and the age group 70 to 79 years were significantly different (P < .05) from adjacent age groups. We estimate that a donor under age 70 years has the potential to donate 4.6 to 6.7 organs. Copyright © 2014 Elsevier Inc. All rights reserved.

Postadsorption Work Function Tuning via Hydrogen Pressure Control

PubMed Central

2015-01-01

The work function of metal substrates can be easily tuned, for instance, by adsorbing layers of molecular electron donors and acceptors. In this work, we discuss the possibility of changing the donor/acceptor mixing ratio reversibly after adsorption by choosing a donor/acceptor pair that is coupled via a redox reaction and that is in equilibrium with a surrounding gas phase. We discuss such a situation for the example of tetrafluoro-1,4-benzenediol (TFBD)/tetrafluoro-1,4-benzoquinone (TFBQ), adsorbed on Cu(111) and Ag(111) surfaces. We use density functional theory and ab initio thermodynamics to show that arbitrary TFBD/TFBQ mixing ratios can be set using hydrogen pressures attainable in low to ultrahigh vacuum. Adjusting the mixing ratio allows modifying the work function over a range of about 1 eV. Finally, we contrast single-species submonolayers with mixed layers to discuss why the resulting inhomogeneities in the electrostatic energy above the surface have different impacts on the interfacial level alignment and the work function. PMID:26692915

The impact of disclosure on donor gamete participants: donors, intended parents and offspring.

PubMed

Greenfeld, Dorothy A

2008-06-01

The present review examines recent publications that provide insight into how the trend toward nonanonymity and disclosure in gamete donation impacts donors, intended parents, and their donor-conceived children. Recent findings show an increase in donor programs that offer open-identity between donors and offspring. The psychological needs of gamete donors and their attitudes toward disclosure are increasingly given consideration. Qualitative research on how parents of donor gamete offspring make decisions about disclosure reveals that even when couples initially disagree about disclosing to offspring, most ultimately come to a united disclosure decision. The literature on the impact of disclosure on donor gamete offspring has extended to include children conceived through embryo donation and children born as a result of surrogacy. The absence of genetic or gestational link between parents and their child does not have a negative impact on parent-child relationships. Parents through surrogacy tend to disclose the method of family creation to their child, whereas parents through embryo donation tend to be secretive about their child's origins. The trend toward greater openness in gamete donation has been accompanied by an increase in programs offering open-identity donation. In addition, the psychological needs of gamete donors and their attitudes toward disclosure are increasingly being given consideration. Parents of donor gamete offspring give careful thought to their disclosure decisions, and the psychological well being of donor-conceived children does not seem to be impacted by those decisions.

Hydrogen bond docking preference in furans: Osbnd H ⋯ π vs. Osbnd H ⋯ O

NASA Astrophysics Data System (ADS)

Jiang, Xiaotong; Tsona, Narcisse T.; Tang, Shanshan; Du, Lin

2018-02-01

The docking sites of hydrogen bonds in complexes formed between 2,2,2-trifluoroethanol (TFE), furan (Fu), and 2-methyl furan (MF) have been investigated. Using density functional theory (DFT) calculations, gas phase and matrix isolation FTIR spectroscopies, the strengths of Osbnd H ⋯ O and Osbnd H ⋯ π hydrogen bonds in the complexes were compared to find the docking preference. Calculations suggest that the hydrogen bond donor, TFE, is more likely to dock onto the oxygen atom of the aromatic furans ring, and consequently, the Osbnd H ⋯ O type hydrogen bond is relatively stronger than the Osbnd H ⋯ π type. The FTIR spectrum in the OH-stretching fundamental range obtained at room temperatures has been compared with that obtained at extremely low temperatures in the matrix. The fundamental and the red shifts of OH-stretching vibrations were observed in both FTIR spectra, confirming the formation of hydrogen bonded complexes. By assessing the ability of furan and MF to participate in the formation of Osbnd H ⋯ O hydrogen bond, the effect of ring methylation has been highlighted. From the calculated geometric and thermodynamic parameters as well as the frequency shift of the OH-stretching vibrations in complexes, TFE-MF is found to be more stable than TFE-Fu, which suggests that the strength of the Osbnd H ⋯ O hydrogen bond in TFE-MF originates from the high activity of the furan molecule caused by the methylation of the aromatic ring. The present study furthers the knowledge of docking preference in heteroaromatic molecules and is helpful to understand the nature of intermolecular interactions between hydrogen bond donors and acceptors, including both electron-deficient atoms and π cloud.

Performance Improvement of V-Fe-Cr-Ti Solid State Hydrogen Storage Materials in Impure Hydrogen Gas.

PubMed

Ulmer, Ulrich; Oertel, Daria; Diemant, Thomas; Bonatto Minella, Christian; Bergfeldt, Thomas; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

2018-01-17

Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O 2 ) impurities in hydrogen (H 2 ) gas. Surface modification is achieved through engineering lanthanum (La)- or nickel (Ni)-rich surface layers with enhanced cyclic stability in an H 2 /O 2 mixture. The formation of a Ni-rich surface layer does not improve the cycling stability in H 2 /O 2 mixtures. Mischmetal (Mm, a mixture of La and Ce) agglomerates are observed within the bulk and surface of the alloy when small amounts of this material are added during arc melting synthesis. These agglomerates provide hydrogen-transparent diffusion pathways into the bulk of the V-Ti-Cr-Fe hydrogen storage alloy when the remaining oxidized surface is already nontransparent for hydrogen. Thus, the cycling stability of the alloy is improved in an O 2 -containing hydrogen environment as compared to the same alloy without addition of Mm. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles.

Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas. Task 1, Literature survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1986-02-01

To make the coal-to-hydrogen route economically attractive, improvements are being sought in each step of the process: coal gasification, water-carbon monoxide shift reaction, and hydrogen separation. This report addresses the use of membranes in the hydrogen separation step. The separation of hydrogen from synthesis gas is a major cost element in the manufacture of hydrogen from coal. Separation by membranes is an attractive, new, and still largely unexplored approach to the problem. Membrane processes are inherently simple and efficient and often have lower capital and operating costs than conventional processes. In this report current ad future trends in hydrogen productionmore » and use are first summarized. Methods of producing hydrogen from coal are then discussed, with particular emphasis on the Texaco entrained flow gasifier and on current methods of separating hydrogen from this gas stream. The potential for membrane separations in the process is then examined. In particular, the use of membranes for H{sub 2}/CO{sub 2}, H{sub 2}/CO, and H{sub 2}/N{sub 2} separations is discussed. 43 refs., 14 figs., 6 tabs.« less

A qualitative quantum rate model for hydrogen transfer in soybean lipoxygenase

NASA Astrophysics Data System (ADS)

Jevtic, S.; Anders, J.

2017-09-01

The hydrogen transfer reaction catalysed by soybean lipoxygenase (SLO) has been the focus of intense study following observations of a high kinetic isotope effect (KIE). Today high KIEs are generally thought to indicate departure from classical rate theory and are seen as a strong signature of tunnelling of the transferring particle, hydrogen or one of its isotopes, through the reaction energy barrier. In this paper, we build a qualitative quantum rate model with few free parameters that describes the dynamics of the transferring particle when it is exposed to energetic potentials exerted by the donor and the acceptor. The enzyme's impact on the dynamics is modelled by an additional energetic term, an oscillatory contribution known as "gating." By varying two key parameters, the gating frequency and the mean donor-acceptor separation, the model is able to reproduce well the KIE data for SLO wild-type and a variety of SLO mutants over the experimentally accessible temperature range. While SLO-specific constants have been considered here, it is possible to adapt these for other enzymes.

Differences in social representation of blood donation between donors and non-donors: an empirical study.

PubMed

Guarnaccia, Cinzia; Giannone, Francesca; Falgares, Giorgio; Caligaris, Aldo Ozino; Sales-Wuillemin, Edith

2015-11-04

Both donors and non-donors have a positive image of blood donation, so donors and non-donors do not differ regarding their views on donation but do differ in converting their opinion into an active deed of donation. Several studies have identified altruism and empathy as the main factors underlying blood donation. However, a mixture of various motivational factors mould the complex behaviour of donation. This paper presents an exploratory study on differences of social representations of blood donation between blood donors and non-donors, in order to understand the reasons that bring someone to take the decision to become a blood donor. Participants filled in the Adapted Self-Report Altruism Scale, Toronto Empathy Questionnaire and answered a test of verbal association. Descriptive and correlation analyses were carried out on quantitative data, while a prototypic analysis was used for qualitative data. The study was carried out on a convenience sample of 786 individuals, 583 donors (mean age: 35.40 years, SD: 13.01 years; 39.3% female) and 203 non-donors (mean age: 35.10 years, SD: 13.30 years; 67.5% female). Social representations of donors seem to be more complex and articulated than those of non-donors. The terms that appear to be central were more specific in donors (life, needle, blood, help, altruism were the words most associated by non-donors; life, aid, altruism, solidarity, health, love, gift, generosity, voluntary, control, needed, useful, needle were the words most associated by donors). Furthermore, non-donors associated a larger number of terms referring to negative aspects of blood donation. Aspects related to training and the accuracy of any information on blood donation seem to be important in the decision to become a donor and stabilise the behaviour of donation over time, thus ensuring the highest levels of quality and safety in blood establishments.

[Five years of Fiom KID-DNA Databank: experiences in matching sperm donors and donor-conceived offspring].

PubMed

Postema, D; Maas, A J B M

2016-01-01

Before the introduction of the Dutch Human Fertilisation (Donor Information) Act (in Dutch: Wet Donorgegevens Kunstmatige Bevruchting) in 2004, approximately 40,000 donor-conceived offspring were born in the Netherlands. The majority is conceived by means of artificial insemination with anonymous donor sperm (in Dutch: kunstmatige inseminatie met anoniem donorzaad - KID). This means that they have little or no access to information about their genetic origins. Through the Fiom KID-DNA Databank, established in 2010 in association with the Canisius Wilhelmina Hospital, it is possible for these donor-conceived offspring and donors to search for one another. DNA profiles are used to match donor-conceived offspring, donors and half-siblings. It is expected that the number of donor-related searches will increase. The experiences with matching and counselling of donor-conceived offspring and donors presented in this paper will help donor-conceived offspring and donors who start a search in the future. Moreover, they provide guidance for forming a meaningful relationship between those involved.

Pure laparoscopic living donor hepatectomy: Focus on 55 donors undergoing right hepatectomy.

PubMed

Suh, K S; Hong, S K; Lee, K W; Yi, N J; Kim, H S; Ahn, S W; Yoon, K C; Choi, J Y; Oh, D; Kim, H

2018-02-01

Although laparoscopic donor hepatectomy is increasingly common, few centers with substantial experience have reported the results of pure laparoscopic donor right hepatectomy (PLDRH). Here, we report the experiences of 60 consecutive liver donors undergoing pure laparoscopic donor hepatectomy (PLDH), with most undergoing right hepatectomy. None of the 60 donors who underwent PLDH had intraoperative complications and none required transfusions, reoperation, or conversion to open hepatectomy. Forty-five donors who underwent PLDRH between November 2015 and December 2016 were compared with 42 who underwent conventional donor right hepatectomy (CDRH) between May 2013 and February 2014. The total operation time was longer (330.7 vs 280.0 minutes; P < .001) and the percentage with multiple bile duct openings was higher (53.3% vs 26.2%; P = .010) in the PLDRH group. However, the length of postoperative hospital stay (8.4 vs 8.2 days; P = .495) and rate of complications (11.9% vs 8.9%; P = .733) and re-hospitalizations (4.8% vs 4.4%; P = 1.000) were similar in both groups. PLDH, including PLDRH, is feasible when performed by a highly experienced surgeon and transplant team. Further evaluation, including long-term results, may support these preliminary findings of comparative outcomes for donors undergoing PLDRH and CDRH. © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

The blood donor identity survey: a multidimensional measure of blood donor motivations.

PubMed

France, Christopher R; Kowalsky, Jennifer M; France, Janis L; Himawan, Lina K; Kessler, Debra A; Shaz, Beth H

2014-08-01

Evidence indicates that donor identity is an important predictor of donation behavior; however, prior studies have relied on diverse, unidimensional measures with limited psychometric support. The goals of this study were to examine the application of self-determination theory to blood donor motivations and to develop and validate a related multidimensional measure of donor identity. Items were developed and administered electronically to a sample of New York Blood Center (NYBC) donors (n=582) and then to a sample of Ohio University students (n=1005). Following initial confirmatory factor analysis (CFA) on the NYBC sample to identify key items related to self-determination theory's six motivational factors, a revised survey was administered to the university sample to reexamine model fit and to assess survey reliability and validity. Consistent with self-determination theory, for both samples CFAs indicated that the best fit to the data was provided by a six-motivational-factor model, including amotivation, external regulation, introjected regulation, identified regulation, integrated regulation, and intrinsic regulation. The Blood Donor Identity Survey provides a psychometrically sound, multidimensional measure of donor motivations (ranging from unmotivated to donate to increasing levels of autonomous motivation to donate) that is suitable for nondonors as well as donors with varying levels of experience. Future research is needed to examine longitudinal changes in donor identity and its relationship to actual donation behavior. © 2014 AABB.

Evidence for photosensitised hydrogen production from water in the absence of precious metals, redox-mediators and co-catalysts.

PubMed

Salzl, S; Ertl, M; Knör, G

2017-03-22

The water-soluble zinc porphyrin complex Zn(TPPS) 4- with TPPS = tetrakis-(4-sulfonatophenyl)porphyrin surprisingly was found to produce significant amounts of hydrogen from aqueous sulfite or amine solutions under visible-light exposure without requiring any other components such as electron relays or additional proton reduction catalysts. Although the production rates and total amounts of chemically stored fuel obtained under these conditions are still much too low to be relevant for practical applications, the background of this unprecedented observation was further studied in its own right. Since the central metal zinc is unlikely to be involved in proton-coupled electron transfer steps upon long-wavelength irradiation and the process does not seem to be much affected by variations of the electron donor added, the mechanism of photocatalytic H 2 release is suggested to involve previously neglected redox features of the in situ generated hydroporphyrin ligand system in aqueous solution.

Diffusion Study on Dissolved Hydrogen toward Effective Bioremediation of Chlorinated Ethenes in Aquitards

NASA Astrophysics Data System (ADS)

Yoshikawa, M.; Zhang, M.; Takeuchi, M.; Komai, T.

2010-12-01

In Japan, the demand for in-situ remediation of contaminated sediments is expected to increase in the future due to the recent amendment of Soil Contamination Countermeasures Act. The Japanese law requires remediating not only contaminated groundwater but also contaminated sediments including those in aquitards. In-situ remediation of contaminated aquitards has been a challenging issue and bioremediation is considered to be one of the effective techniques. In microbial degradation of chrolinated ethenes such as tetrachloroethene and trichloroethene under anaerobic environments, dissolved hydrogen plays an important role. The dechlorinating microbes utilize hydrogen and chlorinated ethenes as an electron donor and an electron accepter, respectively. The size of hydrogen molecule is extremely small and the diffusion rate of dissolved hydrogen in an aquitard would be the key factor that controls the process of microbial dechlorination. However, the diffusion behavior of dissolved hydrogen in subsurface sediments remains unclear. The purposes of this study are to develop a practically utilizable test apparatus, carry out a series of dissolved hydrogen diffusion tests on representative samples, and illustrate the applicability of bioremediation in aquitards. A completely leak-free apparatus was developed by using aluminum alloy and gas tight rubber. This apparatus is capable of testing specimens with a diameter as large as 100 mm by a length from 5 mm to 10 mm, depending on the maximum grain size within a test specimen. Preliminary tests have been performed with glass beads as an ideal material, commercially available kaolin clay, and core samples taken from a polluted site containing clay minerals. The effective diffusion coefficients of these samples were all on the order of 10E-10 m2/s, though their coefficients of permeability varied between the orders of 10E-2 and 10E-7 cm/s. These results showed that there was no obvious relationship between the effective

The effect of whole-blood donor adverse events on blood donor return rates.

PubMed

Newman, Bruce H; Newman, Daniel T; Ahmad, Raffat; Roth, Arthur J

2006-08-01

Some blood donation-related adverse events (AEs) can negatively impact the blood donor return rate (BDRR) and decrease donor retention. One-thousand randomly selected whole-blood donors were interviewed 3 weeks after a 525-mL index whole-blood donation for seven AEs. The number of return visits and duration of follow-up were recorded for each of the 1000 donors. A negative binomial regression analysis was used to determine the contribution of the four most common AEs to the BDRR, and interactions between these AEs were also evaluated. The four most common AEs were bruise alone (15.1%), sore arm "alone" (7.0%), fatigue "alone" (5.1%), and donor reaction "alone" (4.2%), where "alone" is defined to also include donors who had a bruise but no other AE. The estimated BDRR for donations without AEs was 1.32 visits per year. The estimated BDRRs for the four most common AEs were: bruise alone, 1.32 visits per year; sore arm alone, 1.30 visits per year (2% reduction in BDRR); fatigue alone, 1.06 visits per year (20% reduction in BDRR); and donor reaction alone, 0.87 visits per year (34% reduction in BDRR). The BDRR for donor reaction, fatigue, and sore arm together was 0.20 visits per year (85% reduction in BDRR). Donor reaction had the most negative impact on the BDRR. There appears to be a synergistic effect between donor reaction, fatigue, and sore arm. Theoretically, amelioration of some AEs has the potential to improve BDRRs.

Selecting the best haploidentical donor.

PubMed

McCurdy, Shannon R; Fuchs, Ephraim J

2016-10-01

The substantial evidence of the safety of human leukocyte antigen (HLA)-haploidentical (haplo) blood or marrow transplantation (BMT) has led to its increasing utilization. When prioritizing HLA-matched grafts, patients frequently have few or no donors from whom to choose. However, a given patient may have multiple suitable haplo donors. Therefore factors other than HLA-match become critical for selecting the best donor. We recommend a donor selection algorithm based on the donor-specific antibodies, ABO match, donor age, donor sex, and cytomegalovirus (CMV) serostatus match. Despite provocative initial evidence, further studies are warranted to determine whether there is any benefit to selecting a haplo donor based on the number of HLA-mismatches, natural killer cell alloreactivity, or the presence of non-inherited maternal HLA antigens. Copyright © 2016 Elsevier Inc. All rights reserved.

Donor states in a semimagnetic Cd1 -xinMnxin Te /Cd1 -xoutMnxout Te Double Quantum Well

NASA Astrophysics Data System (ADS)

Kalpana, Panneer Selvam; Nithiananthi, Perumal; Jayakumar, Kalyanasundaram

2017-02-01

The theoretical investigation has been carried out on the binding energy of donor associated with the electrons confined in a Cd1 -xinMnxin Te /Cd1 -xoutMnxout Te Double Quantum Well (DQW) as a function of central barrier width for various well dimensions and impurity locations in the barrier and the well. The magnetic field can act as a tool to continuously change the interwell coupling inside this DQW systems and its effect on donor binding has also been studied. Moreover, the polaronic corrections, which is due to the strong exchange interaction between the magnetic moment of Mn2+ ion and the spin of the confined carrier, to the binding energy of the hydrogenic donor impurity has also been estimated with and without the application of magnetic field. The binding energy of the donor impurity is determined by solving the Schrodinger equation variationally in the effective mass approximation and the effect due to Bound Magnetic Polaron (BMP) is included using mean field theory with the modified Brillouin function. The results are reported and discussed.

Rapid onset of squamous cell carcinoma in a thin skin graft donor site.

PubMed

Herard, C; Arnaud, D; Goga, D; Rousseau, P; Potier, B

2016-01-01

Squamous cell carcinomas are malignant tumours of epithelial origin that can appear on sites subjected to chronic inflammation after a period of several years. The rapid development of squamous cell carcinoma at the donor site for a thin skin graft is a rare and poorly understood situation. We report the case of a patient undergoing thin skin grafting to cover the area of removal of a vertex squamous cell carcinoma and in whom squamous cell carcinoma appeared at the donor site within 9 weeks. In our case, we ruled out intraoperative contamination because two sets of surgical instruments were used. Given the number of cases reported in the literature, a chance event seems unlikely. The hypothesis of an acute inflammatory process caused by scarring of the thin skin graft site appears to us the most convincing. Development of cancer at the graft donor site may thus be added to the list of complications of thin skin grafting. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Hot topics in liver transplantation: organ allocation--extended criteria donor--living donor liver transplantation.

PubMed

Müllhaupt, Beat; Dimitroulis, Dimitrios; Gerlach, J Tilman; Clavien, Pierre-Alain

2008-01-01

Liver transplantation has become the mainstay for the treatment of end-stage liver disease, hepatocellular cancer and some metabolic disorders. Its main drawback, though, is the disparity between the number of donors and the patients needing a liver graft. In this review we will discuss the recent changes regarding organ allocation, extended donor criteria, living donor liver transplantation and potential room for improvement. The gap between the number of donors and patients needing a liver graft forced the transplant community to introduce an objective model such as the modified model for end-stage liver disease (MELD) in order to obtain a transparent and fair organ allocation system. The use of extended criteria donor livers such as organs from older donors or steatotic grafts is one possibility to reduce the gap between patients on the waiting list and available donors. Finally, living donor liver transplantation has become a standard procedure in specialized centers as another possibility to reduce the donor shortage. Recent data clearly indicate that center experience is of major importance in achieving good results. Great progress has been made in recent years. However, further research is needed to improve results in the future.

Lung donor treatment protocol in brain dead-donors: A multicenter study.

PubMed

Miñambres, Eduardo; Pérez-Villares, Jose Miguel; Chico-Fernández, Mario; Zabalegui, Arturo; Dueñas-Jurado, Jose María; Misis, Maite; Mosteiro, Fernando; Rodriguez-Caravaca, Gil; Coll, Elisabeth

2015-06-01

The shortage of lung donors for transplantation is the main limitation among patients awaiting this type of surgery. We previously demonstrated that an intensive lung donor-treatment protocol succeeded in increasing the lung procurement rate. We aimed to validate our protocol for centers with or without lung transplant programs. A quasi-experimental study was performed to compare lung donor rate before (historical group, 2010 to 2012) and after (prospective group, 2013) the application of a lung management protocol for donors after brain death (DBDs) in six Spanish hospitals. Lung donor selection criteria remained unchanged in both periods. Outcome measures for lung recipients were early survival and primary graft dysfunction (PGD) rates. A total of 618 DBDs were included: 453 in the control period and 165 in the protocol period. Donor baseline characteristics were similar in both periods. Lung donation rate in the prospective group was 27.3%, more than twice that of the historical group (13%; p < 0.001). The number of lungs retrieved, grafts transplanted, and transplants performed more than doubled over the study period. No differences in early recipients' survival between groups were observed (87.6% vs. 84.5%; p = 0.733) nor in the rate of PGD. Implementing our intensive lung donor-treatment protocol increases lung procurement rates. This allows more lung transplants to be performed without detriment to either early survival or PGD rate. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

NREL Driving Research on Hydrogen Fuel Cells | News | NREL

Science.gov Websites

embrittlement and to reduce the high capital costs of installing completely independent infrastructure. Lowering carbon. The high-pressure hydrogen gas cylinders on board release just enough hydrogen through the stack make containers, but without some of the added chemicals. NREL is examining which chemicals can be

The interaction among donor characteristics, severity of liver disease, and the cost of liver transplantation.

PubMed

Salvalaggio, Paolo R; Dzebisashvili, Nino; MacLeod, Kara E; Lentine, Krista L; Gheorghian, Adrian; Schnitzler, Mark A; Hohmann, Samuel; Segev, Dorry L; Gentry, Sommer E; Axelrod, David A

2011-03-01

Accurate assessment of the impact of donor quality on liver transplant (LT) costs has been limited by the lack of a large, multicenter study of detailed clinical and economic data. A novel, retrospective database linking information from the University HealthSystem Consortium and the Organ Procurement and Transplantation Network registry was analyzed using multivariate regression to determine the relationship between donor quality (assessed through the Donor Risk Index [DRI]), recipient illness severity, and total inpatient costs (transplant and all readmissions) for 1 year following LT. Cost data were available for 9059 LT recipients. Increasing MELD score, higher DRI, simultaneous liver-kidney transplant, female sex, and prior liver transplant were associated with increasing cost of LT (P < 0.05). MELD and DRI interact to synergistically increase the cost of LT (P < 0.05). Donors in the highest DRI quartile added close to $12,000 to the cost of transplantation and nearly $22,000 to posttransplant costs in comparison to the lowest risk donors. Among the individual components of the DRI, donation after cardiac death (increased costs by $20,769 versus brain dead donors) had the greatest impact on transplant costs. Overall, 1-year costs were increased in older donors, minority donors, nationally shared organs, and those with cold ischemic times of 7-13 hours (P < 0.05 for all). In conclusion, donor quality, as measured by the DRI, is an independent predictor of LT costs in the perioperative and postoperative periods. Centers in highly competitive regions that perform transplantation on higher MELD patients with high DRI livers may be particularly affected by the synergistic impact of these factors. Copyright © 2011 American Association for the Study of Liver Diseases.

Iron-titanium-mischmetal alloys for hydrogen storage

DOEpatents

Sandrock, Gary Dale

1978-01-01

A method for the preparation of an iron-titanium-mischmetal alloy which is used for the storage of hydrogen. The alloy is prepared by air-melting an iron charge in a clay-graphite crucible, adding titanium and deoxidizing with mischmetal. The resultant alloy contains less than about 0.1% oxygen and exhibits a capability for hydrogen sorption in less than half the time required by vacuum-melted, iron-titanium alloys.

A frequent, GxxxG-mediated, transmembrane association motif is optimized for the formation of interhelical Cα–H hydrogen bonds

PubMed Central

Mueller, Benjamin K.; Subramaniam, Sabareesh; Senes, Alessandro

2014-01-01

Carbon hydrogen bonds between Cα–H donors and carbonyl acceptors are frequently observed between transmembrane helices (Cα–H···O=C). Networks of these interactions occur often at helix−helix interfaces mediated by GxxxG and similar patterns. Cα–H hydrogen bonds have been hypothesized to be important in membrane protein folding and association, but evidence that they are major determinants of helix association is still lacking. Here we present a comprehensive geometric analysis of homodimeric helices that demonstrates the existence of a single region in conformational space with high propensity for Cα–H···O=C hydrogen bond formation. This region corresponds to the most frequent motif for parallel dimers, GASright, whose best-known example is glycophorin A. The finding suggests a causal link between the high frequency of occurrence of GASright and its propensity for carbon hydrogen bond formation. Investigation of the sequence dependency of the motif determined that Gly residues are required at specific positions where only Gly can act as a donor with its “side chain” Hα. Gly also reduces the steric barrier for non-Gly amino acids at other positions to act as Cα donors, promoting the formation of cooperative hydrogen bonding networks. These findings offer a structural rationale for the occurrence of GxxxG patterns at the GASright interface. The analysis identified the conformational space and the sequence requirement of Cα–H···O=C mediated motifs; we took advantage of these results to develop a structural prediction method. The resulting program, CATM, predicts ab initio the known high-resolution structures of homodimeric GASright motifs at near-atomic level. PMID:24569864

Isomer-Specific Hydrogen Bonding as a Design Principle for Bidirectionally Quantitative and Redshifted Hemithioindigo Photoswitches.

PubMed

Zweig, Joshua E; Newhouse, Timothy R

2017-08-16

A new class of bidirectionally quantitative photoswitches based on the hemithioindigo (HTI) scaffold is reported. Incorporation of a pyrrole hydrogen-bond donor leads to a bathochromic shift allowing for quantitative bidirectional isomerization. Additionally, extending conjugation from the electron-rich pyrrole results in quantitative visible-light photoswitches, as well as photoswitches that isomerize with red and near-infrared light. The presence of the hydrogen bond leading to the observed redshift is supported by computational and spectroscopic evidence.

The influence of the donor-recipient relationship on related donor reactions to stem cell donation.

PubMed

Labott, S; Pfammatter, A

2014-06-01

Previous research has begun to delineate the complicated reactions experienced by bone marrow and stem cell donors. The purpose of this study was to examine the influence of the donor-recipient relationship on the related donor's emotional reactions. Twenty-eight adult stem cell donors completed questionnaires before donation, 30 days post stem cell infusion, and 1 year after infusion. Questionnaires addressed the donor-recipient relationship, depression, mood, guilt and responsibility, self-esteem, ambivalence about donation and reactions to the donation itself. Results indicated that most donors reported little ambivalence about donation, and their reactions to the donation itself were generally positive. Closer and more positive donor-recipient relationships were associated with less anticipated guilt and responsibility if the transplant did not work. The relationships between the donor and the recipient did not change over time. Mood disturbance and depression were low overall, not related to the donor-recipient relationship, and did not significantly change over time. These results indicate that related stem cell donors are generally without significant emotional distress, and are comfortable with the donation process. Further, a more positive relationship with the recipient may help donors to avoid feeling guilty and responsible if the transplant does not work.

Demonstration of the Catalytic Decomposition of Hydrogen Peroxide

NASA Astrophysics Data System (ADS)

Conklin, Alfred R., Jr.; Kessinger, Angela

1996-09-01

Catalytic decomposition is demonstrated by placing hydrogen peroxide solutions in a one liter graduated cylinder and adding soap, food coloring, and potassium iodide. Released oxygen is trapped by the soap producing bubbles. The volume of bubbles is proportional to the concentration of hydrogen peroxide. Chloride and bromide do not cause decomposition. Increased reactant temperature increases the volume of bubbles formed.

Kinetics of sulfate and hydrogen uptake by the thermophilic sulfate-reducing bacteria Thermodesulfobacterium sp. strain JSP and Thermodesulfovibrio sp. strain R1Ha3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sonne-Hansen, J.; Ahring, B.K.; Westermann, P.

1999-03-01

Dissimilatory sulfate reduction and methanogenesis are the main terminal processes in the anaerobic food chain. Both the sulfate-reducing bacteria (SRB) and the methane-producing archaea (MPA) use acetate and hydrogen as substrates and, therefore, compete for common electron donors in sulfate-containing natural environments. Due to a higher affinity for the electron donors acetate and hydrogen, SRB outcompete MPA for these compounds whenever sulfate is present in sufficient concentrations. Half-saturation constants (K{sub m}), maximum uptake rates (V{sub max}), and threshold concentrations for sulfate and hydrogen were determined for two thermophilic sulfate-reducing bacteria (SRB) in an incubation system without headspace. K{sub m} valuesmore » determined for the thermophilic SRB were similar to the constants described for mesophilic SRB isolated from environments with low sulfate concentrations.« less

Achieving donor management goals before deceased donor procurement is associated with more organs transplanted per donor.

PubMed

Malinoski, Darren J; Daly, Michael C; Patel, Madhukar S; Oley-Graybill, Chrystal; Foster, Clarence E; Salim, Ali

2011-10-01

There is a national shortage of organs available for transplantation. Implementation of preset donor management goals (DMGs) to improve outcomes is recommended, but uniform practices and data are lacking. We hypothesized that meeting DMGs before organ procurement would result in more organs transplanted per donor (OTPD). The eight organ procurement organization in United Network for Organ Sharing Region 5 selected 10 critical care end points as DMGs. Each organ procurement organization submitted retrospective data from 40 standard criteria donors. "DMGs met" was defined as achieving any eight DMGs before procurement. The primary outcome was ≥4 OTPD. Binary logistic regression was used to determine independent predictors of ≥4 OTPD with a p<0.05. Three hundred twenty standard criteria donors had 3.6±1.6 OTPD. Donors with DMGs met had more OTPD (4.4 vs. 3.3, p<0.001) and were more likely to have ≥4 OTPD (70% vs. 39%, p<0.001). Independent predictors of ≥4 OTPD were age (odds ratio [OR]=0.94), serum creatinine (OR=0.65), thyroid hormone use (OR=2.0), "DMGs met" (OR=4.4), and achieving the following individual DMGs: central venous pressure 4 mm Hg to 10 mm Hg (OR=1.9), ejection fraction>50% (OR=4.0), Pao2:FIO2>300 (OR=4.6), and serum sodium 135 to 160 mEq/L (OR=3.4). Meeting DMGs before procurement resulted in more OTPD. Donor factors and critical care end points are independent predictors of organ yield. Prospective studies are needed to determine the true impact of each DMG on the number and function of transplanted organs.

Donor Safety in Living Donor Liver Transplantation: A Single-Center Analysis of 300 Cases

PubMed Central

Lei, Jianyong; Yan, Lunan; Wang, Wentao

2013-01-01

Aim To evaluate the safety to donors of living-donor liver transplantation. Methods This study included 300 consecutive living liver tissue donors who underwent operations at our center from July 2002 to December 2012. We evaluated the safety of donors with regard to three aspects complications were recorded prospectively and stratified by grade according to Clavien’s classification, and the data were compared in two stages (the first 5 years’ experience (pre-January 2008) and the latter 5 years’ experience (post-January 2008); laboratory tests such as liver function and blood biochemistry were performed; and the health-related quality of life was evaluated. Results There was no donor mortality at our center, and the overall morbidity rate was 25.3%. Most of the complications of living donors were either grade I or II. There were significantly fewer complications in the latter period of our study than in the initial period (19.9% vs 32.6%, P<0.001), and biliary complications were the most common complications, with an incidence of 9%. All of the liver dysfunction was temporary; however, the post-operative suppression of platelet count lasted for years. Although within the normal range, eight years after operation, 22 donors showed lower platelet levels (189×109/L) compared with the pre-operative levels (267×109/L) (P<0.05). A total of 98.4% of donors had returned to their previous levels of social activity and work, and 99.2% of donors would donate again if it was required and feasible. With the exception of two donors who experienced grade III complications (whose recipients died) and a few cases of abdominal discomfort, fatigue, chronic pain and scar itching, none of the living donors were affected by physical problems. Conclusion With careful donor selection and specialized patient care, low morbidity rates and satisfactory long-term recovery can be achieved after hepatectomy for living-donor liver transplantation. PMID:23637904

Donor safety in living donor liver transplantation: a single-center analysis of 300 cases.

PubMed

Lei, Jianyong; Yan, Lunan; Wang, Wentao

2013-01-01

To evaluate the safety to donors of living-donor liver transplantation. This study included 300 consecutive living liver tissue donors who underwent operations at our center from July 2002 to December 2012. We evaluated the safety of donors with regard to three aspects complications were recorded prospectively and stratified by grade according to Clavien's classification, and the data were compared in two stages (the first 5 years' experience (pre-January 2008) and the latter 5 years' experience (post-January 2008); laboratory tests such as liver function and blood biochemistry were performed; and the health-related quality of life was evaluated. There was no donor mortality at our center, and the overall morbidity rate was 25.3%. Most of the complications of living donors were either grade I or II. There were significantly fewer complications in the latter period of our study than in the initial period (19.9% vs 32.6%, P<0.001), and biliary complications were the most common complications, with an incidence of 9%. All of the liver dysfunction was temporary; however, the post-operative suppression of platelet count lasted for years. Although within the normal range, eight years after operation, 22 donors showed lower platelet levels (189 × 10(9)/L) compared with the pre-operative levels (267 × 10(9)/L) (P<0.05). A total of 98.4% of donors had returned to their previous levels of social activity and work, and 99.2% of donors would donate again if it was required and feasible. With the exception of two donors who experienced grade III complications (whose recipients died) and a few cases of abdominal discomfort, fatigue, chronic pain and scar itching, none of the living donors were affected by physical problems. With careful donor selection and specialized patient care, low morbidity rates and satisfactory long-term recovery can be achieved after hepatectomy for living-donor liver transplantation.

Hydrogen storage material and process using graphite additive with metal-doped complex hydrides

DOEpatents

Zidan, Ragaiy [Aiken, SC; Ritter, James A [Lexington, SC; Ebner, Armin D [Lexington, SC; Wang, Jun [Columbia, SC; Holland, Charles E [Cayce, SC

2008-06-10

A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

On the physical origin of blue-shifted hydrogen bonds.

PubMed

Li, Xiaosong; Liu, Lei; Schlegel, H Bernhard

2002-08-14

For blue-shifted hydrogen-bonded systems, the hydrogen stretching frequency increases rather than decreases on complexation. In computations at various levels of theory, the blue-shift in the archetypical system, F(3)C-H.FH, is reproduced at the Hartree-Fock level, indicating that electron correlation is not the primary cause. Calculations also demonstrate that a blue-shift does not require either a carbon center or the absence of a lone pair on the proton donor, because F(3)Si-H.OH(2), F(2)NH.FH, F(2)PH.NH(3), and F(2)PH.OH(2) have substantial blue-shifts. Orbital interactions are shown to lengthen the X-H bond and lower its vibrational frequency, and thus cannot be the source of the blue-shift. In the F(3)CH.FH system, the charge redistribution in F(3)CH can be reproduced very well by replacing the FH with a simple dipole, which suggests that the interactions are predominantly electrostatic. When modeled with a point charge for the proton acceptor, attractive electrostatic interactions elongate the F(3)C-H, while repulsive interactions shorten it. At the equilibrium geometry of a hydrogen-bonded complex, the electrostatic attraction between the dipole moments of the proton donor and proton acceptor must be balanced by the Pauli repulsion between the two fragments. In the absence of orbital interactions that cause bond elongation, this repulsive interaction leads to compression of the X-H bond and a blue-shift in its vibrational frequency.

Alternative allogeneic donor sources for transplantation for childhood diseases: unrelated cord blood and haploidentical family donors.

PubMed

Cairo, Mitchell S; Rocha, Vanderson; Gluckman, Eliane; Hale, Gregory; Wagner, John

2008-01-01

Allogeneic stem cell transplantation has been demonstrated to be curative in a wide variety of pediatric malignant and nonmalignant diseases, and can be traced back over 50 years ago to the original report of Thomas et al. HLA matched sibling donors have been the gold standard for pediatric recipients requiring allogeneic donors for both nonmalignant and malignant conditions. However, only 25% of potential pediatric recipients possesses an HLA-matched sibling donor, and the frequency is even less in those with genetic nonmalignant conditions because of genetically affected other siblings within the family. Therefore, 75% to 90% of potential pediatric recipients require alternative allogeneic donor cells for treatment of their underlying conditions. Potential alternative allogeneic donor sources include unrelated cord blood donors, unrelated adult donors, and haploidentical family donors. In this article we review the experience of both unrelated cord blood donor and haploidentical family donor transplants in selected pediatric malignant and nonmalignant conditions.

Feasibility of liver graft procurement with donor gallbladder preservation in living donor liver transplantation.

PubMed

Dong, Jia-Hong; Ye, Sheng; Duan, Wei-Dong; Ji, Wen-Bing; Liang, Yu-Rong

2015-10-01

Cholecystectomy is routinely performed at most transplant centers during living donor liver transplantation (LDLT). This study was performed to evaluate the feasibility of liver graft procurement with donor gallbladder preservation in LDLT. Eighty-nine LDLTs (from June 2006 to Dec 2012) were retrospectively analyzed at our hospital. The surgical approach for liver graft procurement with donor gallbladder preservation was assessed, and the anatomy of the cystic artery, the morphology and contractibility of the preserved gallbladder, postoperative symptoms, and vascular and biliary complications were compared among donors with or without gallbladder preservation. Twenty-eight donors (15 right and 13 left-liver grafts) successfully underwent liver graft procurement with gallbladder preservation. Among the 15 right lobectomy donors, for 12 cases (80.0 %) the cystic artery originated from right hepatic artery. From the left hepatic artery and proper hepatic artery accounted for 6.7 % (1/15), respectively. Postoperative symptoms among these 28 donors were slight, although donors with cholecystectomy often complained of fatty food aversion, dyspepsia, and diarrhea during an average follow-up of 58.6 (44-78) months. The morphology and contractibility of the preserved gallbladders were comparable with normal status; the rate of contraction was 53.8 and 76.7 %, respectively, 30 and 60 min after ingestion of a fatty meal. Biliary and vascular complications among donors and recipients, irrespective of gallbladder preservation, were not significantly different. These data suggest that for donors compliant with anatomical requirements, liver graft procurement with gallbladder preservation for the donor is feasible and safe. The preserved gallbladder was assessed as functioning well and postoperative symptoms as a result of cholecystectomy were significantly reduced during long-term follow-up.

First-time blood donors: demographic trends.

PubMed

Wu, Y; Glynn, S A; Schreiber, G B; Wright, D J; Lo, A; Murphy, E L; Kleinman, S H; Garratty, G

2001-03-01

With changing demographics of the United States population and the continuous need to recruit new donors, it is important to monitor the demographic profile of first-time donors and to evaluate changes in the donor pool to improve recruitment targeting. First-time whole blood (n = 901,862) donors at five United States blood centers between 1991 and 1996 were analyzed. The total number of first-time donors appears to be decreasing. Over the 6-year period, there was an overall increase in the proportion of Hispanic and other minority first-time donors and a concurrent decrease in the proportion of white donors at Retrovirus Epidemiology Donor Study centers. Other variables, including age, sex, and education, did not show a consistent trend. The demographic profile of first-time donors is changing. These data highlight the importance for blood centers to continuously monitor the donor population. A better understanding of the donor population may help blood centers adjust their donor outreach, recruitment, and retention programs. New recruitment efforts appear needed to counter general apathy toward donating blood, and minority groups appear to be receptive to becoming blood donors.

Energy status of pig donor organs after ischemia is independent of donor type.

PubMed

Stadlbauer, Vanessa; Stiegler, Philipp; Taeubl, Philipp; Sereinigg, Michael; Puntschart, Andreas; Bradatsch, Andrea; Curcic, Pero; Seifert-Held, Thomas; Zmugg, Gerda; Stojakovic, Tatjana; Leopold, Barbara; Blattl, Daniela; Horki, Vera; Mayrhauser, Ursula; Wiederstein-Grasser, Iris; Leber, Bettina; Jürgens, Günther; Tscheliessnigg, Karlheinz; Hallström, Seth

2013-04-01

Literature is controversial whether organs from living donors have a better graft function than brain dead (BD) and non-heart-beating donor organs. Success of transplantation has been correlated with high-energy phosphate (HEP) contents of the graft. HEP contents in heart, liver, kidney, and pancreas from living, BD, and donation after cardiac death in a pig model (n=6 per donor type) were evaluated systematically. BD was induced under general anesthesia by inflating a balloon in the epidural space. Ten hours after confirmation, organs were retrieved. Cardiac arrest was induced by 9V direct current. After 10min of ventricular fibrillation without cardiac output, mechanical and medical reanimation was performed for 30min before organ retrieval. In living donors, organs were explanted immediately. Freeze-clamped biopsies were taken before perfusion with Celsior solution (heart) or University of Wisconsin solution (abdominal organs) in BD and living donors or with Histidine-Tryptophan-Ketoglutaric solution (all organs) in non-heart-beating donors, after perfusion, and after cold ischemia (4h for heart, 6h for liver and pancreas, and 12h for kidney). HEPs (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, and phosphocreatine), xanthine, and hypoxanthine were measured by high-performance liquid chromatography. Energy charge and adenosine triphosphate-to-adenosine diphosphate ratio were calculated. After ischemia, organs from different donor types showed no difference in energy status. In all organs, a decrease of HEP and an increase in hypoxanthine contents were observed during perfusion and ischemia, irrespective of the donor type. Organs from BD or non-heart-beating donors do not differ from living donor organs in their energy status after average tolerable ischemia. Copyright © 2013 Elsevier Inc. All rights reserved.

Frequency and risk factors for donor reactions in an anonymous blood donor survey.

PubMed

Goldman, Mindy; Osmond, Lori; Yi, Qi-Long; Cameron-Choi, Keltie; O'Brien, Sheila F

2013-09-01

Adverse donor reactions can result in injury and decrease the likelihood of donor return. Reaction reports captured in the blood center's database provide an incomplete picture of reaction rates and risk factors. We performed an anonymous survey, mailed to 40,000 donors in 2008, including questions about symptoms, height, weight, sex, and donation status. Reaction rates were compared to those recorded in our database. Possible risk factors were assessed for various reactions. The response rate was 45.5%. A total of 32% of first-time and 14% of repeat donors reported having any adverse symptom, most frequently bruising (84.9 per 1000 donors) or feeling faint or weak (66.2 per 1000). Faint reactions were two to eight times higher than reported in our database, although direct comparison was difficult. Younger age, female sex, and first-time donation status were risk factors for systemic and arm symptoms. In females, low estimated blood volume (EBV) was a risk factor for systemic symptoms. Only 51% of donors who consulted an outside physician also called Canadian Blood Services. A total of 10% of first-time donors with reactions found adverse effects information inadequate. This study allowed us to collect more information about adverse reactions, including minor symptoms and delayed reactions. Based on our findings of the risk factors and frequency of adverse reactions, we are implementing more stringent EBV criteria for younger donors and providing more detailed information to donors about possible adverse effects and their management. © 2012 American Association of Blood Banks.

Hydrogen bonding in a mixture of protic ionic liquids: a molecular dynamics simulation study.

PubMed

Paschek, Dietmar; Golub, Benjamin; Ludwig, Ralf

2015-04-07

We report results of molecular dynamics (MD) simulations characterising the hydrogen bonding in mixtures of two different protic ionic liquids sharing the same cation: triethylammonium-methylsulfonate (TEAMS) and triethylammonium-triflate (TEATF). The triethylammonium-cation acts as a hydrogen-bond donor, being able to donate a single hydrogen-bond. Both, the methylsulfonate- and the triflate-anions can act as hydrogen-bond acceptors, which can accept multiple hydrogen bonds via their respective SO3-groups. In addition, replacing a methyl-group in the methylsulfonate by a trifluoromethyl-group in the triflate significantly weakens the strength of a hydrogen bond from an adjacent triethylammonium cation to the oxygen-site in the SO3-group of the anion. Our MD simulations show that these subtle differences in hydrogen bond strength significantly affect the formation of differently-sized hydrogen-bonded aggregates in these mixtures as a function of the mixture-composition. Moreover, the reported hydrogen-bonded cluster sizes can be predicted and explained by a simple combinatorial lattice model, based on the approximate coordination number of the ions, and using statistical weights that mostly account for the fact that each anion can only accept three hydrogen bonds.

Electron transfer across multiple hydrogen bonds: the case of ureapyrimidinedione-substituted vinyl ruthenium and osmium complexes.

PubMed

Pichlmaier, Markus; Winter, Rainer F; Zabel, Manfred; Zális, Stanislav

2009-04-08

Ruthenium and osmium complexes 2a,b and 3a,b featuring the N-4,6-dioxo-5,5-dibutyl- or the N-4,6-dioxo-5,5-di-(2-propenyl)-1,4,5,6-tetrahydropyrimidin-2-yl-N'(4-ethenylphenyl)-urea ligand dimerize by a self-complementary quadruply hydrogen-bonding donor/donor/acceptor/acceptor (DDAA) motif. We provide evidence that the dimeric structures are maintained in nonpolar solvents and in 0.1 M NBu(4)PF(6)/CH(2)Cl(2) supporting electrolyte solution. All complexes are reversibly oxidized in two consecutive two-electron oxidations (DeltaE(1/2) approximately = 500 mV) without any discernible potential splitting for the oxidation of the individual hydrogen-bridged redox active moieties. IR and UV/vis/NIR spectroelectrochemistry show a one-step conversion of the neutral to the dication without any discernible features of an intermediate monooxidized radical cation. Oxidation-induced IR changes of the NH and CO groups that are involved in hydrogen bonding are restricted to the styryl-bonded urea NH function. IR band assignments are aided by quantum chemical calculations. Our experimental findings clearly show that, at least in the present systems, the ureapyrimidinedione (Upy) DDAA hydrogen-bonding motif does not support electron transfer. The apparent reason is that neither of the hydrogen-bonding functionalities contributes to the occupied frontier levels. This results in nearly degenerate pairs of MOs representing the in-phase and out-of-phase combinations of the individual monomeric building blocks.

An Overview of Natural Gas Conversion Technologies for Co-Production of Hydrogen and Value-Added Solid Carbon Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dagle, Robert A.; Dagle, Vanessa; Bearden, Mark D.

This report was prepared in response to the U.S. Department of Energy Fuel Cell Technologies Office Congressional Appropriation language to support research on carbon-free production of hydrogen using new chemical processes that utilize natural gas to produce solid carbon and hydrogen. The U.S. produces 9-10 million tons of hydrogen annually with more than 95% of the hydrogen produced by steam-methane reforming (SMR) of natural gas. SMR is attractive because of its high hydrogen yield; but it also converts the carbon to carbon dioxide. Non-oxidative thermal decomposition of methane to carbon and hydrogen is an alternative to SMR and produces COmore » 2-free hydrogen. The produced carbon can be sold as a co-product, thus providing economic credit that reduces the delivered net cost of hydrogen. The combination of producing hydrogen with potentially valuable carbon byproducts has market value in that this allows greater flexibility to match the market prices of hydrogen and carbon. That is, the higher value product can subsidize the other in pricing decisions. In this report we highlight the relevant technologies reported in the literature—primarily thermochemical and plasma conversion processes—and recent research progress and commercial activities. Longstanding technical challenges include the high energetic requirements (e.g., high temperatures and/or electricity requirements) necessary for methane activation and, for some catalytic processes, the separation of solid carbon product from the spent catalyst. We assess current and new carbon product markets that could be served given technological advances, and we discuss technical barriers and potential areas of research to address these needs. We provide preliminary economic analysis for these processes and compare to other emerging (e.g., electrolysis) and conventional (e.g., SMR) processes for hydrogen production. The overarching conclusion of this study is that the cost of hydrogen can be potentially

Alternative Donor Graft Sources for Adults with Hematologic Malignancies: A Donor for All Patients in 2017!

PubMed

Kindwall-Keller, Tamila L; Ballen, Karen K

2017-09-01

Hematopoietic stem cell transplant (HSCT) is potentially curative for a wide variety of malignant diseases, including acute and leukemias, lymphoma, and myelodysplasia. Choice of a stem cell donor is dependent on donor availability, donor compatibility and health, recipient disease type, and recipient condition. Current sources of stem cell donation for HSCT are matched sibling donors (MSDs), matched unrelated donors (MUDs), 1-antigen mismatched unrelated donors (MMUDs), haploidentical donors (haplo), and umbilical cord blood (UCB) units. Historically, preferred donors for HSCT have been human leukocyte antigen (HLA)-matched sibling donors; however, only about 30% of U.S. patients will have a MSD available. The majority of patients referred for HSCT will require an alternative donor graft: MUD, MMUD, UCB, or haplo. The likelihood of finding a MUD varies depending on the ethnicity of the recipient. White Caucasians of European descent have the greatest chance of finding a MUD. Chances of finding a MUD are significantly less for African-American or Hispanic recipients due to HLA polymorphisms. Therefore, MMUD, UCB, and haplo donor graft sources expand the donor pool for recipients who do not have a MSD or MUD available. Given the variety of different donor stem cell sources available today, nearly every patient who needs an allogeneic HSCT has a potential donor in 2017. All transplant-eligible patients with hematologic malignancies should be evaluated by a transplant center to determine if HSCT is a viable treatment option for their underlying disease process. The goal of this review is to increase the awareness of oncology practitioners to the availability of alternative donor stem cell transplants for patients with hematologic malignancies. Despite new agents, stem cell transplant remains the only curative therapy for many patients with acute and chronic leukemia, myelodysplasia, and lymphoma. Given the variety of different donor stem cell sources available today

Our Future Donors

ERIC Educational Resources Information Center

Miller, Richard E.

2004-01-01

The rhetorical advantages and dangers involved in casting the students as "future donors" are explained. The way in which the institutions have to change for casting its students as future donors is described.

Hydrogen ions associated with the dry deposition of pollen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noll, K.E.; Khalili, E.K.

The data provided in this paper demonstrates that pollen can generate significant amounts of hydrogen ions when added to water and that the deposition of tree pollen in forested areas represents a significant hydrogen ion source. Measurements of dry deposition of pollen were made during the months of May and June, 1987 in Northern Wisconsin, using a smooth surrogate surface. Rain samples were also collected. Deposited particles were weighed to determine mass fluxes, then washed and ion chromatographed for SO {sub 4} = and NO {sub 3} {minus} analysis. Species of pollen collected from different types of trees during themore » sampling period were analyzed for SO{sub 4} = NO {sub 3} and other trace constituents. The micrograms of hydrogen ions (protons) generated per gram for different types of pollen added to water, were measured. From 56 to 566 gm were generated per gram or pollen added. The amount generated varied with pollen type. Based on this information, the equivalent protons from the dry deposition of pollen were calculated and compared with the wet deposition proton data. The sulfate, nitrate, and protons associated with dry deposition were of a magnitude comparable with wet deposition.« less

Remuneration of hematopoietic stem cell donors: principles and perspective of the World Marrow Donor Association.

PubMed

Boo, Michael; van Walraven, Suzanna M; Chapman, Jeremy; Lindberg, Brian; Schmidt, Alexander H; Shaw, Bronwen E; Switzer, Galen E; Yang, Edward; Egeland, Torstein

2011-01-06

Hematopoietic stem cell transplantation is a curative procedure for life-threatening hematologic diseases. Donation of hematopoietic stem cells (HSCs) from an unrelated donor, frequently residing in another country, may be the only option for 70% of those in need of unrelated hematopoietic stem cell transplantation. To maximize the opportunity to find the best available donor, individual donor registries collaborate internationally. To provide homogeneity of practice among registries, the World Marrow Donor Association (WMDA) sets standards against which registries are accredited and provides guidance and regulations about unrelated donor safety and care. A basic tenet of the donor registries is that unrelated HSC donation is an altruistic act; nonpayment of donors is entrenched in the WMDA standards and in international practice. In the United States, the prohibition against remuneration of donors has recently been challenged. Here, we describe the reasons that the WMDA continues to believe that HSC donors should not be paid because of ethical concerns raised by remuneration, potential to damage the public will to act altruistically, the potential for coercion and exploitation of donors, increased risk to patients, harm to local transplantation programs and international stem cell exchange, and the possibility of benefiting some patients while disadvantaging others.

Impact of hydrogen refueling configurations and market parameters on the refueling cost of hydrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddi, Krishna; Elgowainy, Amgad; Rustagi, Neha

The cost of hydrogen in early fuel cell electric vehicle (FCEV) markets is dominated by the cost of refueling stations, mainly due to the high cost of refueling equipment, small station capacities, lack of economies of scale, and low utilization of the installed refueling capacity. Using the hydrogen delivery scenario analysis model (HDSAM), this study estimates the impacts of these factors on the refueling cost for different refueling technologies and configurations, and quantifies the potential reduction in future hydrogen refueling cost compared to today’s cost in the United States. The current hydrogen refueling station levelized cost, for a 200 kg/daymore » dispensing capacity, is in the range of 6–8 dollars/kg H 2 when supplied with gaseous hydrogen, and 8–9 dollars/kg H 2 for stations supplied with liquid hydrogen. After adding the cost of hydrogen production, packaging, and transportation to the station’s levelized cost, the current cost of hydrogen at dispensers for FCEVs in California is in the range of 13–15 dollars/kg H 2. The refueling station capacity utilization strongly influences the hydrogen refueling cost. The underutilization of station capacity in early FCEV markets, such as in California, results in a levelized station cost that is approximately 40% higher than it would be in a scenario where the station had been fully utilized since it began operating. In future mature hydrogen FCEV markets, with a large demand for hydrogen, the refueling station’s levelized cost can be reduced to 2 dollars/kg H 2 as a result of improved capacity utilization and reduced equipment cost via learning and economies of scale.« less

Impact of hydrogen refueling configurations and market parameters on the refueling cost of hydrogen

DOE PAGES

Reddi, Krishna; Elgowainy, Amgad; Rustagi, Neha; ...

2017-06-30

The cost of hydrogen in early fuel cell electric vehicle (FCEV) markets is dominated by the cost of refueling stations, mainly due to the high cost of refueling equipment, small station capacities, lack of economies of scale, and low utilization of the installed refueling capacity. Using the hydrogen delivery scenario analysis model (HDSAM), this study estimates the impacts of these factors on the refueling cost for different refueling technologies and configurations, and quantifies the potential reduction in future hydrogen refueling cost compared to today’s cost in the United States. The current hydrogen refueling station levelized cost, for a 200 kg/daymore » dispensing capacity, is in the range of 6–8 dollars/kg H 2 when supplied with gaseous hydrogen, and 8–9 dollars/kg H 2 for stations supplied with liquid hydrogen. After adding the cost of hydrogen production, packaging, and transportation to the station’s levelized cost, the current cost of hydrogen at dispensers for FCEVs in California is in the range of 13–15 dollars/kg H 2. The refueling station capacity utilization strongly influences the hydrogen refueling cost. The underutilization of station capacity in early FCEV markets, such as in California, results in a levelized station cost that is approximately 40% higher than it would be in a scenario where the station had been fully utilized since it began operating. In future mature hydrogen FCEV markets, with a large demand for hydrogen, the refueling station’s levelized cost can be reduced to 2 dollars/kg H 2 as a result of improved capacity utilization and reduced equipment cost via learning and economies of scale.« less

Comparable Outcomes after HLA-Matched Sibling and Alternative Donor Hematopoietic Cell Transplantation for Children with Fanconi Anemia and Severe Aplastic Anemia.

PubMed

Ebens, Christen L; DeFor, Todd E; Tryon, Rebecca; Wagner, John E; MacMillan, Margaret L

2018-04-01

Fanconi anemia (FA)-associated severe aplastic anemia (SAA) requires allogeneic hematopoietic cell transplantation (HCT) for cure. With the evolution of conditioning regimens over time, outcomes of alternative donor HCT (AD-HCT) have improved dramatically. We compared outcomes of HLA-matched sibling donor HCT (MSD-HCT; n = 17) and AD-HCT (n = 57) performed for FA-associated SAA at a single institution between 2001 and 2016. Overall survival at 5 years was 94% for MSD-HCT versus 86% for AD-HCT, neutrophil engraftment was 100% versus 95%, platelet recovery was 100% versus 89%, grade II-IV acute graft-versus-host disease (GVHD) was 6% versus 12%, grade III-IV acute GVHD was 6% versus 4%, and chronic GVHD was 0 versus 7%, with no statistically significant differences by type of transplant. The use of UCB was associated with decreased rates of neutrophil recovery in AD-HCT and platelet recovery in both MSD-HCT and AD-HCT. A trend toward a higher serious infection density before day +100 post-HCT was observed in AD-HCT compared with MSD-HCT (P = .02). These data demonstrate that AD-HCT should be considered at the same time as MSD-HCT for patients with FA-associated SAA. Copyright © 2017 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Validation of systems biology derived molecular markers of renal donor organ status associated with long term allograft function.

PubMed

Perco, Paul; Heinzel, Andreas; Leierer, Johannes; Schneeberger, Stefan; Bösmüller, Claudia; Oberhuber, Rupert; Wagner, Silvia; Engler, Franziska; Mayer, Gert

2018-05-03

Donor organ quality affects long term outcome after renal transplantation. A variety of prognostic molecular markers is available, yet their validity often remains undetermined. A network-based molecular model reflecting donor kidney status based on transcriptomics data and molecular features reported in scientific literature to be associated with chronic allograft nephropathy was created. Significantly enriched biological processes were identified and representative markers were selected. An independent kidney pre-implantation transcriptomics dataset of 76 organs was used to predict estimated glomerular filtration rate (eGFR) values twelve months after transplantation using available clinical data and marker expression values. The best-performing regression model solely based on the clinical parameters donor age, donor gender, and recipient gender explained 17% of variance in post-transplant eGFR values. The five molecular markers EGF, CD2BP2, RALBP1, SF3B1, and DDX19B representing key molecular processes of the constructed renal donor organ status molecular model in addition to the clinical parameters significantly improved model performance (p-value = 0.0007) explaining around 33% of the variability of eGFR values twelve months after transplantation. Collectively, molecular markers reflecting donor organ status significantly add to prediction of post-transplant renal function when added to the clinical parameters donor age and gender.

Hydrogen Transfer during Liquefaction of Elbistan Lignite to Biomass; Total Reaction Transformation Approach

NASA Astrophysics Data System (ADS)

Koyunoglu, Cemil; Karaca, Hüseyin

2017-12-01

Given the high cost of the tetraline solvent commonly used in liquefaction, the use of manure with EL is an important factor when considering the high cost of using tetraline as a hydrogen transfer source. In addition, due to the another cost factor which is the catalyst prices, red mud (commonly used, produced as a byproduct in the production of aluminium) is reduced cost in the work of liquefaction of coal, biomass, even coal combined biomass, corresponding that making the EL liquefaction an agenda for our country is another important factor. Conditions for liquefaction experiments conducted for hydrogen transfer from manure to coal; Catalyst concentration of 9%, liquid/solid ratio of 3/1, reaction time of 60 min, fertilizer/lignite ratio of 1/3, and the reaction temperature of 400 °C, the stirred speed of 400 rpm and the initial nitrogen pressure of 20 bar was fixed. In order to demonstrate the hydrogen, transfer from manure to coal, coal is used solely, by using tetraline (also known as a hydrogen carrier) and distilled water which is not hydrogen donor as a solvent in the co-liquefaction of experiments, and also the liquefaction conditions are carried out under an inert (N2) gas atmosphere. According to the results of the obtained liquefaction test; using tetraline solvent the total liquid product conversion percentage of the oil + gas conversion was 38.3 %, however, the results of oil+gas conversion obtained using distilled water and EL combined with manure the total liquid product conversion percentage was 7.4 %. According to the results of calorific value and elemental analysis, only the ratio of (H/C)atomic of coal obtained by using tetraline increased with the liquefaction of manure and distilled water. The reason of the increase in the amount of hydrogen due to hydrogen transfer from the manure on the solid surface of the coal, and also on the surface of the inner pore of the coal during the liquefaction, brings about the evaluation of the coal as a

Cyanobacterial Hydrogenases and Hydrogen Metabolism Revisited: Recent Progress and Future Prospects

PubMed Central

Khanna, Namita; Lindblad, Peter

2015-01-01

Cyanobacteria have garnered interest as potential cell factories for hydrogen production. In conjunction with photosynthesis, these organisms can utilize inexpensive inorganic substrates and solar energy for simultaneous biosynthesis and hydrogen evolution. However, the hydrogen yield associated with these organisms remains far too low to compete with the existing chemical processes. Our limited understanding of the cellular hydrogen production pathway is a primary setback in the potential scale-up of this process. In this regard, the present review discusses the recent insight around ferredoxin/flavodoxin as the likely electron donor to the bidirectional Hox hydrogenase instead of the generally accepted NAD(P)H. This may have far reaching implications in powering solar driven hydrogen production. However, it is evident that a successful hydrogen-producing candidate would likely integrate enzymatic traits from different species. Engineering the [NiFe] hydrogenases for optimal catalytic efficiency or expression of a high turnover [FeFe] hydrogenase in these photo-autotrophs may facilitate the development of strains to reach target levels of biohydrogen production in cyanobacteria. The fundamental advancements achieved in these fields are also summarized in this review. PMID:26006225

Impact of the Cornea Donor Study (CDS) on Acceptance of Corneas from Older Donors

PubMed Central

Sugar, Alan; Montoya, Monty M.; Beck, Roy; Cowden, John W.; Dontchev, Mariya; Gal, Robin L.; Kollman, Craig; Malling, Jackie; Mannis, Mark J.; Tennant, Bradley

2014-01-01

Purpose Evaluate retrospectively whether findings from the Cornea Donor Study (CDS) led to changes in the transplantation of corneas from older donors. Methods United States eye banks provided complete data on donor age and placement (domestic or international) for 86,273 corneas from 1998 to 2009. The data were analyzed by 3 time periods: preceding CDS (1998–1999), during CDS (2000–2007) and after publication of CDS 5 year results (2008–2009), and separately for corneas placed within vs. outside the United States. Results For corneal tissues transplanted in the United States, the percentage of donors ≥66 years old increased from 19% before CDS to 21% during CDS and 25% after CDS (p<0.001). Corresponding median (25th-75th percentile) donor ages were 53 (39–63), 54 (41–64) and 57 (46–66), respectively (p<0.001). The opposite trend was observed for corneas distributed outside the United States with the percentage of donors ≥66 years old decreasing from 56% to 42% to 34%, respectively. Donor age trends over time varied by eye bank. Conclusions There was a modest overall increase in the donor age of corneas transplanted in the United States from 1998 to 2009, but the retrospective nature of the study limits our ability to attribute this change to the CDS. The modest increases in the donor age of corneas transplanted is a positive finding, but wider acceptance of older corneal donor tissue should be encouraged based on the five-year evidence generated by the CDS. PMID:22262218

Promoting Organ Donor Registries Through Public Education: What Is the Cost of Securing Organ Donors?

PubMed

Razdan, Manik; Smith, Kenneth J; Bryce, Cindy L; Degenholtz, Howard B

2016-06-01

Transplant medicine's impact on America's public health is seriously limited by acute shortage of transplantable organs. Consequently, the United Sates has witnessed considerable investment in the promotion of organ donor registries. Although there is no evidence to support that donor registry promotion alleviates organ shortage, this belief continues to drive investments into registry promotion. In this study, return on investment in donor registry promotion was examined using cost-outcomes analysis. Cost of promoting the donor registry was estimated in US dollars whereas the outcome was measured as the number of individuals who join the registry (registrants) and their value in terms of organ donors. The study was conducted from the perspective of a regional Organ Procurement Organization (OPO). Costs were directly obtained from the OPO. The number of new registrants was obtained from the OPO and the departments of motor vehicles that maintain the donor registry. The value of registrants in terms of organ donors was computed based on a registrant's age-dependent risk of dying and age-dependent probability of becoming an organ donor. Six thousand seven hundred eight individuals joined the organ donor registry (95% confidence interval [95% CI], 5429-7956) at a cost of $455 per registrant (95% CI, US $383-US $562). These individuals result in 4.2 present-day donors (95% CI, 2.5-6.6) at a cost of US $726 000 (95% CI, US $462000-US $1.2 million). Because the cost per registrant and cost per donor is less than society's willingness to pay, donor registry promotion offers positive return on investment. Investment in registry promotion should at the minimum be maintained at current levels.

Swedish sperm donors are driven by altruism, but shortage of sperm donors leads to reproductive travelling.

PubMed

Ekerhovd, Erling; Faurskov, Anders; Werner, Charlotte

2008-01-01

Swedish legislation requires that sperm donors are identifiable to offspring. In Denmark sperm donors remain anonymous. The aim of this study was to examine sperm donation in Sweden by identifying socio-demographic backgrounds, motivations and attitudes among donors and to describe options and plans of sperm recipients. Furthermore, the willingness of Swedish health care providers to assist in treatment abroad, where sperm from an anonymous donor were to be used, was assessed. The extent of travelling to Denmark for reproductive purposes was also examined. Thirty Swedish sperm donors completed a questionnaire and were interviewed about their backgrounds, motivations and attitudes. Thirty couples where the infertility workup had shown azoospermia were interviewed about their options for achieving parenthood. The willingness to assist in fertility treatment abroad and the extent of reproductive cross border travelling were assessed by interviewing health care providers and by contacting Danish clinics. Almost all donors were Caucasian. The main motivation for sperm donors was to help others. Owing to shortage of sperm donors many Caucasian recipients intended to have treatment abroad. For most non-Caucasian recipients sperm from a donor of appropriate ethnicity were not available in Sweden. Whether the sperm donor was anonymous or identifiable was not of major importance to most sperm recipients. Health care providers expressed unanimous willingness to assist in treatment with sperm from an anonymous donor. Our inquiry indicated that more than 250 Swedish sperm recipients travel to Denmark annually. Identifiable sperm donors are driven by altruistic motives, but shortage of sperm donors leads to reproductive travelling. Recruitment strategies to increase the number of sperm donors in Sweden are therefore warranted.

Potential Application of Anaerobic Extremophiles for Hydrogen Production

NASA Technical Reports Server (NTRS)

Pikuta, Elena V.; Hoover, Richard B.

2004-01-01

During substrate fermentation many anaerobes produce the hydrogen as a waste product, which often regulates the growth of the cultures as an inhibitor. In nature the hydrogen is usually removed from the ecosystem due to its physical properties or by consumption of hydrogen by secondary anaerobes, which sometimes behave as competitors for electron donors as is seen in the classical example in anaerobic microbial communities via the interaction between methanogens and sulfate- or sulfur- reducers. It was demonstrated previously on mixed cultures of anaerobes at neutral pH that bacterial hydrogen production could provide an alternative energy source. But at neutral pH the original cultures can easily be contaminated by methanogens, a most unpleasant side effect of these conditions is the development of pathogenic bacteria. In both cases the rate of hydrogen production was dramatically decreased since some part of the hydrogen was transformed to methane, and the cultivation of human pathogens on a global scale is very dangerous. In our laboratory, experiments with obligately alkaliphilic bacteria that excrete hydrogen as the end metabolic product were performed at different temperature regimes. Mesophilic and moderately thermophilic bacterial cultures have been studied and compared for the most effective hydrogen production. For high-mineralized media with pH 9.5-10.0 not many methanogens are known to exist. Furthermore, the development of pathogenic contaminant microorganisms is virtually impossible: carbonate-saturated solutions are used as antiseptics in medicine. Therefore the cultivation of alkaliphilic hydrogen producing bacteria could be considered as most safe process for global Scale industry in future. Here we present experimental data on the rates of hydrogen productivity for mesophilic, alkaliphilic, obligately anaerobic bacterium Spirocheta americana ASpG1 and moderately thermophilic, alkaliphilic, facultative anaerobe Anoxybacillus pushchinoensis K1 and

Formation of Multiple-Phase Catalysts for the Hydrogen Storage of Mg Nanoparticles by Adding Flowerlike NiS.

PubMed

Xie, Xiubo; Ma, Xiujuan; Liu, Peng; Shang, Jiaxiang; Li, Xingguo; Liu, Tong

2017-02-22

In order to enhance the hydrogen storage properties of Mg, flowerlike NiS particles have been successfully prepared by solvothermal reaction method, and are subsequently ball milled with Mg nanoparticles (NPs) to fabricate Mg-5 wt % NiS nanocomposite. The nanocomposite displays Mg/NiS core/shell structure. The NiS shell decomposes into Ni, MgS and Mg 2 Ni multiple-phases, decorating on the surface of the Mg NPs after the first hydrogen absorption and desorption cycle at 673 K. The Mg-MgS-Mg 2 Ni-Ni nanocomposite shows enhanced hydrogenation and dehydrogenation rates: it can quickly uptake 3.5 wt % H 2 within 10 min at 423 K and release 3.1 wt % H 2 within 10 min at 573 K. The apparent hydrogen absorption and desorption activation energies are decreased to 45.45 and 64.71 kJ mol -1 . The enhanced sorption kinetics of the nanocomposite is attributed to the synergistic catalytic effects of the in situ formed MgS, Ni and Mg 2 Ni multiple-phase catalysts during the hydrogenation/dehydrogenation process, the porthole effects for the volume expansion and microstrain of the phase transformation of Mg 2 Ni and Mg 2 NiH 4 and the reduced hydrogen diffusion distance caused by nanosized Mg. This novel method of in situ producing multiple-phase catalysts gives a new horizon for designing high performance hydrogen storage material.

Delays in Prior Living Kidney Donors Receiving Priority on the Transplant Waiting List

PubMed Central

Klassen, David K.; Kucheryavaya, Anna Y.; Stewart, Darren E.

2016-01-01

Background and objectives Prior living donors (PLDs) receive very high priority on the Organ Procurement and Transplantation Network (OPTN) kidney waiting list. Program delays in adding PLDs to the waiting list, setting their status to active, and submitting requests for PLD priority can affect timely access to transplantation. Design, setting, participants, & measurements We used the OPTN and the Centers for Medicare and Medicaid Services data to examine timing of (1) listing relative to start of dialysis, (2) activation on the waiting list, and (3) requests for PLD priority relative to listing date. There were 210 PLDs (221 registrations) added to the OPTN kidney waiting list between January 1, 2010 and July 31, 2015. Results As of September 4, 2015, 167 of the 210 PLDs received deceased donor transplants, six received living donor transplants, two died, five were too sick to transplant, and 29 were still waiting. Median waiting time to deceased donor transplant for PLDs was 98 days. Only 40.7% of 221 PLD registrations (n=90) were listed before they began dialysis; 68.3% were in inactive status for <90 days, 17.6% were in inactive status for 90–365 days, 8.6% were in inactive status for 1–2 years, and 5.4% were in inactive status for >2 years. Median time of PLDs waiting in active status before receiving PLD priority was 2 days (range =0–1450); 67.4% of PLDs received PLD priority within 7 days after activation, but 15.4% waited 8–30 days, 8.1% waited 1–3 months, 4.1% waited 3–12 months, and 5.0% waited >1 year in active status for PLD priority. After receiving priority, most were transplanted quickly. Median time in active status with PLD priority before deceased donor transplant was 23 days. Conclusions Fewer than one half of listed PLDs were listed before starting dialysis. Most listed PLDs are immediately set to active status and receive PLD priority quickly, but a substantial number spends time in active status without PLD priority or a large

Does size matter? Kidney transplant donor size determines kidney function among living donors

PubMed Central

Narasimhamurthy, Meenakshi; Smith, Lachlan M.; Machan, Jason T.; Reinert, Steven E.; Gohh, Reginald Y.; Dworkin, Lance D.; Merhi, Basma; Patel, Nikunjkumar; Beland, Michael D.

2017-01-01

Background Kidney donor outcomes are gaining attention, particularly as donor eligibility criteria continue to expand. Kidney size, a useful predictor of recipient kidney function, also likely correlates with donor outcomes. Although donor evaluation includes donor kidney size measurements, the association between kidney size and outcomes are poorly defined. Methods We examined the relationship between kidney size (body surface area-adjusted total volume, cortical volume and length) and renal outcomes (post-operative recovery and longer-term kidney function) among 85 kidney donors using general linear models and time-to-chronic kidney disease data. Results Donors with the largest adjusted cortical volume were more likely to achieve an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 over a median 24-month follow-up than those with smaller cortical volumes (P <0.001), had a shorter duration of renal recovery (1.3–2.2 versus 32.5 days) and started with a higher eGFR at pre-donation (107–110 versus 91 mL/min/1.73 m2) and immediately post-nephrectomy (∼63 versus 50–51 mL/min/1.73 m2). Similar findings were seen with adjusted total volume and length. Conclusions Larger kidney donors were more likely to achieve an eGFR ≥60 mL/min/1.73 m2 with renal recovery over a shorter duration due to higher pre-donation and initial post-nephrectomy eGFRs. PMID:28638611

Higher organ donation consent rates by relatives of potential uncontrolled donors versus potential controlled donors after death.

PubMed

Wind, Jentina; van Mook, Walther N K A; Willems, Monique E C; van Heurn, L W Ernest

2012-11-01

Refusal to consent to organ donation is an important cause of the persisting gap between the number of potential organ donors and effectuated donors. In the Netherlands, organ donors include both uncontrolled donors: donors who die unexpectedly after cardiac death (DCD), after failed resuscitation and donors in whom death can be expected and donors after brain death, and controlled DCD donors: those who die after the withdrawal of treatment. Different donor type implies a different setting in which relatives are requested to consent to organ donation. It is unknown whether the setting influences the eventual decision for donation or not. Therefore, we compared the consent rate in potential donors who died unexpectedly (UD group) and in whom death was expected. A total of 523 potential organ donors between 2003 and 2011 in the 715-bed Maastricht University Medical Centre, the Netherlands were included. Both the patients' registration in the national donor register (DR) and the relatives' refusal rate in the two groups were retrospectively assessed using data from the donation application database. There were 109 unexpected and 414 expected potential donors The potential donors in the UD group were younger (mean age 52 versus 55 years, P = 0.032) and more often male (68 versus 52%, P = 0.003). There were no significant differences in registration in the DR between the groups. The relatives' consent rate in non-registered potential donors, or those who mandated the relatives for that decision, was higher in the UD group (53 versus 29%, P < 0.001). Less than 50% of the potential donors were registered in the national DR. Therefore, the relatives have an important role in the choice for organ donation. The relatives of potential donors who died unexpectedly consented more often to donation than those in whom death was expected.

Human decellularized bone scaffolds from aged donors show improved osteoinductive capacity compared to young donor bone.

PubMed

Smith, Christopher A; Board, Tim N; Rooney, Paul; Eagle, Mark J; Richardson, Stephen M; Hoyland, Judith A

2017-01-01

To improve the safe use of allograft bone, decellularization techniques may be utilized to produce acellular scaffolds. Such scaffolds should retain their innate biological and biomechanical capacity and support mesenchymal stem cell (MSC) osteogenic differentiation. However, as allograft bone is derived from a wide age-range, this study aimed to determine whether donor age impacts on the ability an osteoinductive, acellular scaffold produced from human bone to promote the osteogenic differentiation of bone marrow MSCs (BM-MSC). BM-MSCs from young and old donors were seeded on acellular bone cubes from young and old donors undergoing osteoarthritis related hip surgery. All combinations resulted in increased osteogenic gene expression, and alkaline phosphatase (ALP) enzyme activity, however BM-MSCs cultured on old donor bone displayed the largest increases. BM-MSCs cultured in old donor bone conditioned media also displayed higher osteogenic gene expression and ALP activity than those exposed to young donor bone conditioned media. ELISA and Luminex analysis of conditioned media demonstrated similar levels of bioactive factors between age groups; however, IGF binding protein 1 (IGFBP1) concentration was significantly higher in young donor samples. Additionally, structural analysis of old donor bone indicated an increased porosity compared to young donor bone. These results demonstrate the ability of a decellularized scaffold produced from young and old donors to support osteogenic differentiation of cells from young and old donors. Significantly, the older donor bone produced greater osteogenic differentiation which may be related to reduced IGFBP1 bioavailability and increased porosity, potentially explaining the excellent clinical results seen with the use of allograft from aged donors.

Effect of quantum nuclear motion on hydrogen bonding

NASA Astrophysics Data System (ADS)

McKenzie, Ross H.; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G.

2014-05-01

This work considers how the properties of hydrogen bonded complexes, X-H⋯Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H⋯O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4 - 3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends.

The use of neoplastic donors to increase the donor pool.

PubMed

Fiaschetti, P; Pretagostini, R; Stabile, D; Peritore, D; Oliveti, A; Gabbrielli, F; Cenci, S; Ricci, A; Vespasiano, F; Grigioni, W F

2012-09-01

The aim of the study was to evaluate the experience of the Centre-Sud Transplant Organization (OCST) area using cadaveric donor with neoplastic diseases to evaluate the possibility of transmission to recipients. From January 1, 2003, to December 31, 2010, the neoplastic risk has been reported to be 5.4% (377/4654 referred donors). In 2003, the number of donors with a tumor and their mean age were respectively: 60 (10.3%) and 59.6 ± 19.9; 2004: 33 (5.2%) and 61.4 ± 15.9; 2005: 32 (6%) and 62.8 ± 15.5; 2006: 46 (7%) and 60.7 ± 19.1; 2007: 51 (7%) and 58.9 ± 16; in 2008: 58 (7%) and 59.7 ± 19.6; 2009: 47 (7%) and 57 ± 26; 2010: 49 (7%) and 64 ± 16. The organ most affected by tumor has been the central nervous system (18%). The tumor was diagnosed before in 325 (86%) cases, versus during organ retrieval in 48 (12.7%) donor operations but before, which four cases (1%) occured after transplantation. According to the histological types and grades, 28 evaluated donors (8.2%) were suitable for transplantation. The histological types were: thyroid carcinoma (n = 3); prostate carcinoma (n = 8), renal clear cell carcinoma (n = 7), oncocytoma (n = 1), meningiomas (n = 2), dermofibrosarcoma (n = 1); verrucous carcinoma of the vulva (n = 1), colon adenocarcinoma (n = 1), grade II astrocytoma (n = 1), adrenal gland tumor (n = 1), gastric GIST (n = 1), oligodendroglioma (n = 1). Forty-five organs were retrieved (22 livers, 19 kidneys, 3 hearts, and 1 pancreas) and transplanted into 44 recipients with 1 liver-kidney combined transplantation. Four recipients died due to causes not related to the tumor. No donor-transmitted tumor was detected among the recipients. Donation is absolutely not indicated in cases of tumors with high metastatic potential and high grades. Performing an accurate evaluation of the donor, taking into account the histological grade, currently can allow, organ retrieval and transplantation with an acceptable risk. Copyright © 2012. Published by Elsevier

Coupling Glucose Dehydrogenation with CO2 Hydrogenation by Hydrogen Transfer in Aqueous Media at Room Temperature.

PubMed

Ding, Guodong; Su, Ji; Zhang, Cheng; Tang, Kan; Yang, Lisha; Lin, Hongfei

2018-05-08

Conversion of carbon dioxide into value-added chemicals and fuels provides a direct solution to reduce excessive CO2 in the atmosphere. Herein, a novel catalytic reaction system is presented by coupling the dehydrogenation of glucose with the hydrogenation of a CO2 derived salt, ammonium carbonate, in the ethanol-water mixture. For the first time, the hydrogenation of CO2 into formate by glucose has been achieved under ambient conditions. Under the optimal reaction conditions, the highest yield of formate reached ~ 46 %. We find that the apparent pH value in the ethanol-water mixture plays a central role in determining the performance of the hydrogen transfer reaction. Based on the 13C NMR and ESI-MS results, a possible pathway of the coupled glucose dehydrogenation and CO2 hydrogenation reactions was proposed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The impact of meeting donor management goals on the number of organs transplanted per donor: results from the United Network for Organ Sharing Region 5 prospective donor management goals study.

PubMed

Malinoski, Darren J; Patel, Madhukar S; Daly, Michael C; Oley-Graybill, Chrystal; Salim, Ali

2012-10-01

Many organ procurement organizations have implemented critical care end points as donor management goals in efforts to increase organs transplanted per donor after neurologic determination of death. Although retrospective studies have demonstrated an association between meeting donor management goals and organ yield, prospective studies are lacking. In June 2008, nine donor management goals were prospectively implemented as a checklist and every donor after neurologic determination of death was managed to meet them. The donor management goals represented normal cardiovascular, pulmonary, renal, and endocrine end points. Data were collected for 7 months. Donor management goals "met" was defined a priori as achieving any seven of the nine donor management goals, and this was recorded at the time of consent, 12-18 hrs later, and prior to organ recovery. The primary outcome measure was ≥4 organs transplanted per donor, and binary logistic regression was used to identify independent predictors of this outcome with a p<.05. All eight organ procurement organizations in the five Southwestern United States (United Network for Organ Sharing Region 5). All standard criteria donors after neurologic determination of deaths. Prospective implementation of a donor management goal checklist. There were 380 standard criteria donors with 3.6±1.7 organs transplanted per donor. Fifteen percent had donor management goals met at the time of consent, 33% at 12-18 hrs, and 38% prior to organ recovery. Forty-eight percent had ≥4 organs transplanted per donor. Donors with ≥4 organs transplanted per donor had significantly more individual donor management goals met at all three time points. Independent predictors of ≥4 organs transplanted per donor were age (odds ratio=0.95 per year), final creatinine (odds ratio=0.75 per 1-unit increase), donor management goals "met" at consent (odds ratio=2.03), donor management goals "met" prior to organ recovery (odds ratio=2.34), and a change in

Hydrogen bond and halogen bond inside the carbon nanotube

NASA Astrophysics Data System (ADS)

Wang, Weizhou; Wang, Donglai; Zhang, Yu; Ji, Baoming; Tian, Anmin

2011-02-01

The hydrogen bond and halogen bond inside the open-ended single-walled carbon nanotubes have been investigated theoretically employing the newly developed density functional M06 with the suitable basis set and the natural bond orbital analysis. Comparing with the hydrogen or halogen bond in the gas phase, we find that the strength of the hydrogen or halogen bond inside the carbon nanotube will become weaker if there is a larger intramolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom donor to the antibonding orbital of the X-H or X-Hal bond involved in the formation of the hydrogen or halogen bond and will become stronger if there is a larger intermolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom acceptor to the antibonding orbital of the X-H or X-Hal bond. According to the analysis of the molecular electrostatic potential of the carbon nanotube, the driving force for the electron-density transfer is found to be the negative electric field formed in the carbon nanotube inner phase. Our results also show that the X-H bond involved in the formation of the hydrogen bond and the X-Hal bond involved in the formation of the halogen bond are all elongated when encapsulating the hydrogen bond and halogen bond within the carbon nanotube, so the carbon nanotube confinement may change the blue-shifting hydrogen bond and the blue-shifting halogen bond into the red-shifting hydrogen bond and the red-shifting halogen bond. The possibility to replace the all electron nanotube-confined calculation by the simple polarizable continuum model is also evaluated.

Female-partnered and single women's contact motivations and experiences with donor-linked families.

PubMed

Goldberg, A E; Scheib, J E

2015-06-01

What are female-partnered and single mothers' motivations and experiences at one donor insemination (DI) program with regard to contacting other families who share the same sperm donor? By and large, women reported seeking contact to obtain (i) support for their children and/or themselves, and (ii) information about shared traits and medical problems, ultimately describing a range of contact experiences, both positive (e.g. special bond created) and negative (e.g. uncomfortable encounters). There is a growing phenomenon of donor insemination families-parents and/or offspring-seeking others who share their donor (i.e. are 'donor-linked'). There is limited understanding about parental motivations and experiences-especially in the presence of a second parent-due to the methodological constraints of previous quantitative studies. Semi-structured telephone interviews were conducted with 50 donor insemination mothers (14 single, 36 female-partnered). Participants were recruited by email invitation to parent members of a family-matching service at one donor insemination program in the USA. The criterion for inclusion was having matched to at least one donor-linked family. Among the 50 mothers interviewed, all had at least one child conceived via donor insemination, who was between ages 0 and 15 years at first contact. Families matched with a median of three donor-linked families (range 1-10). Interview data were analyzed through qualitative (i.e. thematic) analysis. Overarching themes emerged of seeking contact to obtain (i) support and (ii) information about children's shared physical and psychological traits. Some wanted to increase their child's family network, through adding a sibling, but more often as extended family. Data, from partnered parents especially, revealed the challenges of balancing the boundaries of family formed without the genetic link with the perceived benefits of exploring the child's donor origins. Interviews focused on openness and information

Family experience of waiting for living donor liver transplantation: from parental donor perspective.

PubMed

Chou, Chu-Yi; Chen, Yu-Chih; Chen, Chao-Long; Chen, Jo-Lin; Mu, Pei-Fan

2009-06-01

The aim of this study was to investigate from the perspectives of the donor parents of children with biliary atresia, the essence of family experiences during the period when waiting for a living donor liver transplant. Living donor liver transplantation is a new hope for children and families when the child suffers from biliary atresia. It is obvious, during the waiting period, for a family with a child undergoing living donor liver transplantation, that the process has a serious impact and there is a need for them to be well-prepared. A descriptive phenomenological design was used in this study. Nine donor parents from a medical centre in Taiwan participated in this study. The inclusion criteria were that the parent had a child with biliary atresia, that the child had received living donor liver transplantation over the last year and a half and that the parent was the living donor for child's liver transplantation. An open in-depth interview technique encouraged the parents to reflect on their experiences as the process raised their feelings to a conscious level. The data were analysed using the Colaizzi's approach. This study explores the essence of families undergoing the waiting period for living donor liver transplantation surgery from the point of view of the donating parents. Five themes emerged: (1) surgery as hope of rebirth, (2) negotiating the decision to have surgery, (3) the selection of the donor to achieve family welfare, (4) preparing and planning for the surgery and (5) worry over the impact of the surgery. The results demonstrate that the parents' experiences included a variety of domains: hope of rebirth, mental negotiation while deciding on surgery and choice of donor, coping with the preparation for surgery and the possible impact on the family of the surgery. The findings indicated that nursing professionals should provide family-centred care to assist the family with the steps needed to move toward surgery.

Development of an Unrelated Donor Selection Score Predictive of Survival after HCT: Donor Age Matters Most.

PubMed

Shaw, Bronwen E; Logan, Brent R; Spellman, Stephen R; Marsh, Steven G E; Robinson, James; Pidala, Joseph; Hurley, Carolyn; Barker, Juliet; Maiers, Martin; Dehn, Jason; Wang, Hailin; Haagenson, Mike; Porter, David; Petersdorf, Effie W; Woolfrey, Ann; Horowitz, Mary M; Verneris, Michael; Hsu, Katharine C; Fleischhauer, Katharina; Lee, Stephanie J

2018-05-01

Donor factors, in addition to HLA matching status, have been associated with recipient survival in unrelated donor (URD) hematopoietic cell transplantation (HCT); however, there is no hierarchical algorithm that weights the characteristics of individual donors against each other in a quantitative manner to facilitate donor selection. The goal of this study was to develop and validate a donor selection score that prioritizes donor characteristics associated with better survival in 8/8 HLA-matched URDs. Two separate patient/donor cohorts, the first receiving HCT between 1999 and 2011 (n = 5952, c1), and the second between 2012 and 2014 (n = 4510, c2) were included in the analysis. Both cohorts were randomly spilt, 2:1, into training and testing sets. Despite studying over 10,000 URD transplants, we were unable to validate a donor selection score. The only donor characteristic associated with better survival was younger age, with 2-year survival being 3% better when a donor 10 years younger is selected. These results support previous studies suggesting prioritization of a younger 8/8 HLA-matched donor. This large dataset also shows that none of the other donor clinical factors tested were reproducibly associated with survival, and hence flexibility in selecting URDs based on other characteristics is justified. These data support a simplified URD selection process and have significant implications for URD registries. Copyright © 2018 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Psychosocial counselling of identifiable sperm donors.

PubMed

Visser, M; Mochtar, M H; de Melker, A A; van der Veen, F; Repping, S; Gerrits, T

2016-05-01

What do identifiable sperm donors feel about psychosocial counselling? Identifiable sperm donors found it important that psychosocial counselling focused on emotional consequences and on rules and regulations and they expected to have access to psychosocial counselling at the time that donor-offspring actually sought contact. Most studies on sperm donors are on anonymous donors and focus on recruitment, financial compensation, anonymity and motivations. There is limited knowledge on the value that identifiable sperm donors place on psychosocial counselling and what their needs are in this respect. We performed a qualitative study from March until June 2014 with 25 identifiable sperm donors, who were or had been a donor at the Centre for Reproductive Medicine of the Academic Medical Centre in Amsterdam any time between 1989 and 2014. We held semi-structured in-depth interviews with identifiable sperm donors with an average age of 44 years. The interviews were fully transcribed and analysed using the constant comparative method of grounded theory. Twelve out of 15 donors (former donors ITALIC! n = 8, active donors ITALIC! n = 7) who had received a counselling session during their intake procedure found it important that they had been able to talk about issues such as the emotional consequences of donation, disclosure to their own children, family and friends, future contact with donor-offspring and rules and regulations. Of the 10 former donors who had received no counselling session, 8 had regretted the lack of intensive counselling. In the years following their donation, most donors simply wanted to know how many offspring had been born using their sperm and had no need for further counselling. Nevertheless, they frequently mentioned that they were concerned about the well-being of 'their' offspring. In addition, they would value the availability of psychosocial counselling in the event that donor-offspring actually sought contact. A limitation of our study is its

Robotic-assisted single-port donor nephrectomy using the da Vinci single-site platform.

PubMed

LaMattina, John C; Alvarez-Casas, Josue; Lu, Irene; Powell, Jessica M; Sultan, Samuel; Phelan, Michael W; Barth, Rolf N

2018-02-01

Although single-port donor nephrectomy offers improved cosmetic outcomes, technical challenges have limited its application to selected centers. Our center has performed over 400 single-port donor nephrectomies. The da Vinci single-site robotic platform was utilized in an effort to overcome the steric, visualization, ergonomic, and other technical limitations associated with the single-port approach. Food and Drug Administration device exemption was obtained. Selection criteria for kidney donation included body mass index <35, left kidney donors, and ≤2 renal arteries. After colonic mobilization using standard single-port techniques, the robotic approach was utilized for ureteral complex and hilar dissection. Three cases were performed using the robotic single-site platform. Average total operative time was 262 ± 42 min including 82 ± 16 min of robotic use. Docking time took 20 ± 10 min. Blood loss averaged 77 ± 64 mL. No intraoperative complications occurred, and all procedures were completed with our standard laparoscopic single-port approach. This is the first clinical experience of robotic-assisted donor nephrectomy utilizing the da Vinci single-site platform. Our experience supported the safety of this approach but found that the technology added cost and complexity without tangible benefit. Development of articulating instruments, energy, and stapling devices will be necessary for increased application of robotic single-site surgery for donor nephrectomy. Copyright © 2017 Elsevier Inc. All rights reserved.

Use of once-through treat gas to remove the heat of reaction in solvent hydrogenation processes

DOEpatents

Nizamoff, Alan J.

1980-01-01

In a coal liquefaction process wherein feed coal is contacted with molecular hydrogen and a hydrogen-donor solvent in a liquefaction zone to form coal liquids and vapors and coal liquids in the solvent boiling range are thereafter hydrogenated to produce recycle solvent and liquid products, the improvement which comprises separating the effluent from the liquefaction zone into a hot vapor stream and a liquid stream; cooling the entire hot vapor stream sufficiently to condense vaporized liquid hydrocarbons; separating condensed liquid hydrocarbons from the cooled vapor; fractionating the liquid stream to produce coal liquids in the solvent boiling range; dividing the cooled vapor into at least two streams; passing the cooling vapors from one of the streams, the coal liquids in the solvent boiling range, and makeup hydrogen to a solvent hydrogenation zone, catalytically hydrogenating the coal liquids in the solvent boiling range and quenching the hydrogenation zone with cooled vapors from the other cooled vapor stream.

75 FR 58400 - Donor Management Research: Improvements in Clinical Management of Deceased Organ Donors

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-24

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Health Resources and Services Administration Donor Management Research: Improvements in Clinical Management of Deceased Organ Donors AGENCY: Health Resources... their experiences and opinions regarding the importance of further study into donor management and its...

Human decellularized bone scaffolds from aged donors show improved osteoinductive capacity compared to young donor bone

PubMed Central

Smith, Christopher A.; Board, Tim N.; Rooney, Paul; Eagle, Mark J.; Richardson, Stephen M.

2017-01-01

To improve the safe use of allograft bone, decellularization techniques may be utilized to produce acellular scaffolds. Such scaffolds should retain their innate biological and biomechanical capacity and support mesenchymal stem cell (MSC) osteogenic differentiation. However, as allograft bone is derived from a wide age-range, this study aimed to determine whether donor age impacts on the ability an osteoinductive, acellular scaffold produced from human bone to promote the osteogenic differentiation of bone marrow MSCs (BM-MSC). BM-MSCs from young and old donors were seeded on acellular bone cubes from young and old donors undergoing osteoarthritis related hip surgery. All combinations resulted in increased osteogenic gene expression, and alkaline phosphatase (ALP) enzyme activity, however BM-MSCs cultured on old donor bone displayed the largest increases. BM-MSCs cultured in old donor bone conditioned media also displayed higher osteogenic gene expression and ALP activity than those exposed to young donor bone conditioned media. ELISA and Luminex analysis of conditioned media demonstrated similar levels of bioactive factors between age groups; however, IGF binding protein 1 (IGFBP1) concentration was significantly higher in young donor samples. Additionally, structural analysis of old donor bone indicated an increased porosity compared to young donor bone. These results demonstrate the ability of a decellularized scaffold produced from young and old donors to support osteogenic differentiation of cells from young and old donors. Significantly, the older donor bone produced greater osteogenic differentiation which may be related to reduced IGFBP1 bioavailability and increased porosity, potentially explaining the excellent clinical results seen with the use of allograft from aged donors. PMID:28505164

Factors associated with blood transfusion in donor hepatectomy: results from 2344 donors at a large single center.

PubMed

Choi, Seong-Soo; Cho, Seong-Sik; Kim, Sung-Hoon; Jun, In-Gu; Hwang, Gyu-Sam; Kim, Young-Kug

2013-12-15

The safety of healthy living donors undergoing hepatic resection for living-donor liver transplantation is of paramount concern. Although blood transfusions have been associated with morbidity and mortality after hepatectomy, there is limited information about the risk factors associated with blood transfusion in living liver donors. We retrospectively analyzed 2344 donors who underwent a hepatectomy for living-donor liver transplantation. Logistic regression analysis was performed to determine blood transfusion predictors in living-donor hepatectomy. Of these donors, 48 (2.0%) and 97 (4.1%) were transfused with packed red blood cell (PRBC) and fresh-frozen plasma (FFP), respectively. The amount of PRBC and FFP administered to donors transfused with blood products were 1.9±0.8 and 3.7±2.5 units, respectively. In multivariate logistic regression analysis, a low preoperative hemoglobin level was found to be an independent predictor of PRBC transfusion in donor hepatectomy (odds ratio=0.585; 95% confidence interval=0.451-0.758; P<0.001). A high graft-to-donor weight ratio predicted an FFP transfusion in donor hepatectomy (odds ratio=2.997; 95% confidence interval=1.226-7.327; P=0.016). These results indicate that, in donor hepatectomy, the preoperative hemoglobin value and graft-to-donor weight ratio can provide useful information on the probability of PRBC and FFP transfusion, respectively.

Heteroatom-free arene-cobalt and arene-iron catalysts for hydrogenations.

PubMed

Gärtner, Dominik; Welther, Alice; Rad, Babak Rezaei; Wolf, Robert; Jacobi von Wangelin, Axel

2014-04-01

75 years after the discovery of hydroformylation, cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. We have evaluated arene metalates in which the low-valent metal species is--conceptually different from heteroatom-based ligands--stabilized by π coordination to hydrocarbons. Potassium bis(anthracene)cobaltate 1 and -ferrate 2 can be viewed as synthetic precursors of quasi-"naked" anionic metal species; their aggregation is effectively impeded by (labile) coordination to the various π acceptors present in the hydrogenation reactions of unsaturated molecules (alkenes, arenes, carbonyl compounds). Kinetic studies, NMR spectroscopy, and poisoning studies of alkene hydrogenations support the formation of a homogeneous catalyst derived from 1 which is stabilized by the coordination of alkenes. This catalyst concept complements the use of complexes with heteroatom donor ligands for reductive processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Organ-Specific Donor Risk Indices

PubMed Central

Akkina, Sanjeev K.; Asrani, Sumeet K.; Peng, Yi; Stock, Peter; Kim, Ray; Israni, Ajay K.

2012-01-01

Due to the shortage of deceased donor organs, transplant centers accept organs from marginal deceased donors, including older donors. Organ-specific donor risk indices have been developed to predict graft survival using various combinations of donor and recipient characteristics. We will review the kidney donor risk index (KDRI) and liver donor risk index (LDRI) and compare and contrast their strengths, limitations, and potential uses. The Kidney Donor Risk Index has a potential role in developing new kidney allocation algorithms. The Liver Donor Risk Index allows for greater appreciation of the importance of donor factors, particularly for hepatitis C-positive recipients; as the donor risk index increases, rates of allograft and patient survival among these recipients decrease disproportionately. Use of livers with high donor risk index is associated with increased hospital costs independent of recipient risk factors, and transplanting livers with high donor risk index into patients with Model for End-Stage Liver Disease scores < 15 is associated with lower allograft survival; use of the Liver Donor Risk Index has limited this practice. Significant regional variation in donor quality, as measured by the Liver Donor Risk Index, remains in the United States. We also review other potential indices for liver transplant, including donor-recipient matching and the retransplant donor risk index. While substantial progress has been made in developing donor risk indices to objectively assess donor variables that affect transplant outcomes, continued efforts are warranted to improve these indices to enhance organ allocation policies and optimize allograft survival. PMID:22287036

Early donor management increases the retrieval rate of hearts for transplantation in marginal donors.

PubMed

Abuanzeh, Razi; Hashmi, Faisal; Dimarakis, Ioannis; Khasati, Noman; Machaal, Ali; Yonan, Nizar; Venkateswaran, Rajamiyer V

2015-01-01

Organ donations continue to fall, failing to meet the clinical requirements for heart transplantation. Furthermore, the pathophysiology of brain stem death including hormonal and inflammatory changes may lead to significant donor heart injury. Early donor management may potentially alleviate these changes and therefore increase the number of available hearts for transplantation. We aimed to investigate whether early management of borderline donors can increase the heart retrieval rate. Between September 2011 and February 2013, we performed early donor management of 26 potential heart donors in the intensive care units of the respective donor hospitals. At the time of referral donors were considered as borderline based on high-dose inotrope requirements, history of hypertension and cardiopulmonary resuscitation. Our management protocol included insertion of a pulmonary artery catheter and performance of cardiac output studies, weaning noradrenaline and commencing arginine vasopressin, and administration of tri-iodothyronine, methylprednisolone and insulin. Our primary end-point was donor heart acceptance, depending collectively on the results of cardiac output studies, cardiac contractility and coronary artery patency at the time of retrieval operation. We retrieved 14 (56%) borderline hearts after donor management (Group A) with a 30-day survival rate of 86%. Twelve (44%) organs were declined due to poor heart function (n=8; 66.7%; P<0.001) and/or palpable coronary artery disease (n=4; 33.3%; P=0.018) (Group B). The mean age of Groups A and B was 42.77 and 47.78 years, respectively (P=0.19). Most of the female donors, i.e. 10 (83%), were declined, and only 4 (27%) were accepted (P=0.005). Majority of patients in both groups (Group A: 71.4%; n=10; and Group B: 66.7%; n=8) were on high-dose noradrenaline (>0.08 μg kg(-1) min(-2)) at the time of donor offer. Group A had a mean cardiac output of 6.29 and 3.09 l/min for Group B (P=0.01). A positive smoking history was

Hydrogen mitigation in submerged arc welding

NASA Astrophysics Data System (ADS)

Klimowicz, Steven

removes the moisture that is added by the water based binder. The second phase of the project was to modify the flux with fluoride additions to remove hydrogen from the arc while welding. The introduction of fluorine into the arc would lower the amount of hydrogen that may be absorbed as diffusible hydrogen by the weld metal. To select the fluorides a series of thermodynamic calculations were performed as well as simple tests to determine the fluorides behavior in a welding arc and flux. From these tests the following fluorides were selected to be used to be added to EM12K flux as oneweight percent additions: SrF 2, K2TiF6, K2SiF6, and LiF. Welds were then run with the experimental fluxes according to AWS A4.3 standard for diffusible hydrogen testing. From these tests it was found that none experimental fluxes were able to achieve a diffusible hydrogen content lower than the original EM12K flux. It was also found that fluoride reduction in a simple flux is a better predictor of fluoride effectiveness than decomposition temperature.

Differential effects of donor-specific HLA antibodies in living versus deceased donor transplant.

PubMed

Kamburova, E G; Wisse, B W; Joosten, I; Allebes, W A; van der Meer, A; Hilbrands, L B; Baas, M C; Spierings, E; Hack, C E; van Reekum, F E; van Zuilen, A D; Verhaar, M C; Bots, M L; Drop, A C A D; Plaisier, L; Seelen, M A J; Sanders, J S F; Hepkema, B G; Lambeck, A J A; Bungener, L B; Roozendaal, C; Tilanus, M G J; Voorter, C E; Wieten, L; van Duijnhoven, E M; Gelens, M; Christiaans, M H L; van Ittersum, F J; Nurmohamed, S A; Lardy, N M; Swelsen, W; van der Pant, K A; van der Weerd, N C; Ten Berge, I J M; Bemelman, F J; Hoitsma, A; van der Boog, P J M; de Fijter, J W; Betjes, M G H; Heidt, S; Roelen, D L; Claas, F H; Otten, H G

2018-02-21

The presence of donor-specific anti-HLA antibodies (DSAs) is associated with increased risk of graft failure after kidney transplant. We hypothesized that DSAs against HLA class I, class II, or both classes indicate a different risk for graft loss between deceased and living donor transplant. In this study, we investigated the impact of pretransplant DSAs, by using single antigen bead assays, on long-term graft survival in 3237 deceased and 1487 living donor kidney transplants with a negative complement-dependent crossmatch. In living donor transplants, we found a limited effect on graft survival of DSAs against class I or II antigens after transplant. Class I and II DSAs combined resulted in decreased 10-year graft survival (84% to 75%). In contrast, after deceased donor transplant, patients with class I or class II DSAs had a 10-year graft survival of 59% and 60%, respectively, both significantly lower than the survival for patients without DSAs (76%). The combination of class I and II DSAs resulted in a 10-year survival of 54% in deceased donor transplants. In conclusion, class I and II DSAs are a clear risk factor for graft loss in deceased donor transplants, while in living donor transplants, class I and II DSAs seem to be associated with an increased risk for graft failure, but this could not be assessed due to their low prevalence. © 2018 The Authors. American Journal of Transplantation published by Wiley Periodicals, Inc. on behalf of The American Society of Transplantation and the American Society of Transplant Surgeons.

The end of donor anonymity: how genetic testing is likely to drive anonymous gamete donation out of business.

PubMed

Harper, Joyce C; Kennett, Debbie; Reisel, Dan

2016-06-01

Thousands of people worldwide have been conceived using donor gametes, but not all parents tell their children of their origin. Several countries now allow donor-conceived offspring to potentially know their genetic parent if they are informed of their donor-conceived status. At the same time, personal genetic testing is a rapidly expanding field. Over 3 million people have already used direct-to-consumer genetic testing to find information about their ancestry, and many are participating in international genetic genealogy databases that will match them with relatives. The increased prevalence of these technologies poses numerous challenges to the current practice of gamete donation. (i) Whether they are donating in a country that practices anonymous donation or not, donors should be informed that their anonymity is not guaranteed, as they may be traced if their DNA, or that of a relative, is added to a database. (ii) Donor-conceived adults who have not been informed of their status may find out that they are donor-conceived. (iii) Parents using donor conception need to be fully informed that their children's DNA will identify that they are not the biological parents and they should be encouraged to disclose the use of donor gametes to their children. Together, these concerns make urgent a wide-ranging societal conversation about how to best safeguard and promote the interests of donor-conceived offspring and protect the rights of donors. Specifically, there is a need to ensure that new genetic information is communicated in a way that promotes both the safety and the privacy rights of offspring and donors alike. All parties concerned must be aware that, in 2016, donor anonymity does not exist. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Spectroscopically determined force field for water dimer: physically enhanced treatment of hydrogen bonding in molecular mechanics energy functions.

PubMed

Mannfors, Berit; Palmo, Kim; Krimm, Samuel

2008-12-11

Our ab initio transformed spectroscopically determined force field (SDFF) methodology emphasizes, in addition to accurate structure and energy performance, comparable prediction of vibrational properties in order to improve reproduction of interaction forces. It is now applied to the determination of a molecular mechanics (MM) force field for the water monomer and dimer as an initial step in developing a more physically based treatment of the hydrogen bonding that not only underlies condensed-phase water but also must be important in molecular-level protein-water interactions. Essential electrical components of the SDFF for monomer water are found to be the following: an off-plane charge distribution, this distribution consisting of four off-atom charge sites in traditional lone pair (LP) but also in inverted lone pair (ILP) positions; allowance for a diffuse size to these off-atom sites; and the incorporation of charge fluxes (i.e., the change in charge with change in internal coordinate). Parametrization of such an LP/ILP model together with the SDFF analytically transformed valence force field results in essentially exact agreement with ab initio (in this case MP2/6-31++G(d,p)) structure, electrical, and vibrational properties. Although we demonstrate that the properties of this monomer electrical model together with its van der Waals and polarization interactions are transferable to the dimer, this is not sufficient in reproducing comparable dimer properties, most notably the huge increase in infrared intensity of a donor OH stretch mode. This deficiency, which can be eliminated by a large dipole-derivative-determined change in the effective charge flux of the donor hydrogen-bonded OH bond, is not accounted for by the charge flux change in this bond due to the induction effects of the acceptor electric field alone, and can only be fully removed by an added bond flux associated with the extent of overlap of the wave functions of the two molecules. We show that

Large enhancement of X-ray excited luminescence in Ga-doped ZnO nanorod arrays by hydrogen annealing

NASA Astrophysics Data System (ADS)

Li, Qianli; Liu, Xiaoliln; Gu, Mu; Li, Fengrui; Zhang, Juannan; Wu, Qiang; Huang, Shiming; Liu, Si

2018-03-01

Highly c-axis oriented and densely packed ZnO:Ga nanorod arrays were fabricated on ZnO-seeded substrates by hydrothermal method, and the effect of hydrogen annealing on their morphology, structure and luminescence properties was investigated in detail. Under ultraviolet or X-ray excitation, an intense ultraviolet luminescence appeared in the hydrogen-annealed samples owing to the formation of a shallow hydrogen donor state, which can sharply activate the reconbination radiation. The luminescence intensity increased with the annealing temperature, and then decreased at a higher temperature due to the dissociation of the hydrogen ion. The optimum concentration and time of hydrogen annealing were acquired simultaneously. It is expected that the ZnO:Ga nanorod array is a promising candidate for application in ultrafast and high-spatial-resolution X-ray imaging detector.

Compliance with donor age recommendations in oocyte donor recruitment advertisements in the USA.

PubMed

Alberta, Hillary B; Berry, Roberta M; Levine, Aaron D

2013-04-01

IVF using donated oocytes offers benefits to many infertile patients, yet the technique also raises a number of ethical concerns, including worries about potential physical and psychological risks to oocyte donors. In the USA, oversight of oocyte donation consists of a combination of federal and state regulations and self-regulatory guidelines promulgated by the American Society for Reproductive Medicine. This study assesses compliance with one of these self-regulatory guidelines - specifically, ASRM's preferred minimum age for donors of 21. To assess compliance, 539 oocyte donor recruitment advertisements from two recruitment channels (Craigslist and college newspapers) were collected and evaluated. Of these, 61% in the Craigslist dataset and 43% in the college newspaper dataset listed minimum ages between 18 and 20, which is inconsistent with ASRM's preferred minimum age recommendation of 21. Advertisements placed by oocyte donor recruitment agencies were more likely than advertisements placed by clinics to specify minimum ages between 18 and 20. These results indicate that ASRM should evaluate and consider revising its donor age guidelines. IVF using donated human eggs can help many patients who have difficulty having children. However, the technique also raises ethical concerns, including concerns about potential physical and psychological harms to egg donors. In the USA, oversight of egg donation relies on a combination of federal and state regulation and professional self-regulation. Governmental regulations address only limited aspects of egg donation, such as the potential spread of infectious diseases and the reporting of success rates, leaving voluntary guidelines developed by an association of medical professionals to address most issues, including ethical concerns raised by the practice. One of these voluntary guidelines recommends that egg donors should be at least 21 years of age. In this article, we analysed 539 egg donor recruitment advertisements

Sperm donor recruitment, attitudes and provider practices--5 years after the removal of donor anonymity.

PubMed

Shukla, U; Deval, B; Jansa Perez, M; Hamoda, H; Savvas, M; Narvekar, N

2013-03-01

Has the change in donor anonymity legislation in UK affected the recruitment of men wanting to be sperm donors and also affected the attitudes of the practitioners who provide donor sperm treatment? We have performed fewer IUI and IVF treatments using donor sperm following the change in legislation in April 2005 than before. However, we have seen an overall increase in men wanting to donate their sperm, including a small increase in men from ethnic minorities. Sweden, which removed donor anonymity in 1985, had an initial drop in men wanting to donate and then 10 years later started to have an increase. The Human Fertilisation and Embryology Authority (HFEA) and other studies in the UK have shown an overall downward trend, but have not been able to compare large time scales either side of the change in legislation. This was a retrospective descriptive study that looked at all men who approached the clinic between the years 2000 and 2010, i.e. 5 years either side of the change in legislation (April 2005). Overall, we had 24 men wanting to be donors prior to the rule change and 65 men after the rule change. We also investigated the total number of all treatments with donor sperm, and this included a total of 1004 donor sperm treatments prior to the change in legislation and 403 donor sperm treatments after the change in legislation. The study was set in an NHS IVF clinic in South East London. We compared the indicators of service provision, provider practices and donor attitudes, in the period between April 2000 and March 2005 (Group A) with those between April 2005 and March 2010 (Group B), i.e. 5 years either side of the change in legislation. There were 875 IUI treatments and 129 IVF or ICSI treatments in Group A and 325 IUI and 78 IVF/ICSI treatments in Group B with the use of donor sperm, of which, 11.9% (119 out of 1004) in Group A and 39.5% (159 out of 403) in Group B were with donor sperm recruited by our unit. The clinical pregnancy rate per cycle of

Advanced Hydrogen Liquefaction Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, Joseph; Kromer, Brian; Neu, Ben

2011-09-28

The project identified and quantified ways to reduce the cost of hydrogen liquefaction, and reduce the cost of hydrogen distribution. The goal was to reduce the power consumption by 20% and then to reduce the capital cost. Optimizing the process, improving process equipment, and improving ortho-para conversion significantly reduced the power consumption of liquefaction, but by less than 20%. Because the efficiency improvement was less than the target, the program was stopped before the capital cost was addressed. These efficiency improvements could provide a benefit to the public to improve the design of future hydrogen liquefiers. The project increased themore » understanding of hydrogen liquefaction by modeling different processes and thoroughly examining ortho-para separation and conversion. The process modeling provided a benefit to the public because the project incorporated para hydrogen into the process modeling software, so liquefaction processes can be modeled more accurately than using only normal hydrogen. Adding catalyst to the first heat exchanger, a simple method to reduce liquefaction power, was identified, analyzed, and quantified. The demonstrated performance of ortho-para separation is sufficient for at least one identified process concept to show reduced power cost when compared to hydrogen liquefaction processes using conventional ortho-para conversion. The impact of improved ortho-para conversion can be significant because ortho para conversion uses about 20-25% of the total liquefaction power, but performance improvement is necessary to realize a substantial benefit. Most of the energy used in liquefaction is for gas compression. Improvements in hydrogen compression will have a significant impact on overall liquefier efficiency. Improvements to turbines, heat exchangers, and other process equipment will have less impact.« less

Potential State-selective Hydrogen Bond Formation Can Modulate Activation and Desensitization of the α7 Nicotinic Acetylcholine Receptor*

PubMed Central

Wang, Jingyi; Papke, Roger L.; Stokes, Clare; Horenstein, Nicole A.

2012-01-01

A series of arylidene anabaseines were synthesized to probe the functional impact of hydrogen bonding on human α7 nicotinic acetylcholine receptor (nAChR) activation and desensitization. The aryl groups were either hydrogen bond acceptors (furans), donors (pyrroles), or neither (thiophenes). These compounds were tested against a series of point mutants of the ligand-binding domain residue Gln-57, a residue hypothesized to be proximate to the aryl group of the bound agonist and a putative hydrogen bonding partner. Q57K, Q57D, Q57E, and Q57L were chosen to remove the dual hydrogen bonding donor/acceptor ability of Gln-57 and replace it with hydrogen bond donating, hydrogen bond accepting, or nonhydrogen bonding ability. Activation of the receptor was compromised with hydrogen bonding mismatches, for example, pairing a pyrrole with Q57K or Q57L, or a furan anabaseine with Q57D or Q57E. Ligand co-applications with the positive allosteric modulator PNU-120596 produced significantly enhanced currents whose degree of enhancement was greater for 2-furans or -pyrroles than for their 3-substituted isomers, whereas the nonhydrogen bonding thiophenes failed to show this correlation. Interestingly, the PNU-120596 agonist co-application data revealed that for wild-type α7 nAChR, the 3-furan desensitized state was relatively stabilized compared with that of 2-furan, a reversal of the relationship observed with respect to the barrier for entry into the desensitized state. These data highlight the importance of hydrogen bonding on the receptor-ligand state, and suggest that it may be possible to fine-tune features of agonists that mediate state selection in the nAChR. PMID:22556416

The Psychosocial and Independent Living Donor Advocate Evaluation and Post-surgery Care of Living Donors.

PubMed

Rudow, Dianne LaPointe; Swartz, Kathleen; Phillips, Chelsea; Hollenberger, Jennifer; Smith, Taylor; Steel, Jennifer L

2015-09-01

Solid organ transplantation as a treatment for end stage organ failure has been an accepted treatment option for decades. Despite advances in medicine and technology, and increased awareness of organ donation and transplantation, the gap between supply and demand continues to widen. Living donation has been an option that has increased the number of transplants despite the continued shortage of deceased organs. In the early 2000s live donor transplantation reached an all-time high in the United States. As a result, a consensus meeting was convened in 2000 to increase the oversight of living donor transplantation. Both the Centers for Medicare and Medicaid Services and the United Network for Organ Sharing developed regulations that transplant programs performing live donor transplantation. These regulations and guidelines involve the education, evaluation, informed consent process and living donor follow-up care. Two areas in which had significant changes included the psychosocial and the independent living donor advocate (ILDA) evaluation. The purpose of this paper was to outline the current regulations and guidelines associated with the psychosocial and ILDA evaluation as well as provide further recommendations for the administration of a high quality evaluation of living donors. The goals and timing of the evaluation and education of donors; qualifications of the health care providers performing the evaluation; components of the evaluation; education provided to donors; documentation of the evaluation; participation in the selection committee meeting; post-decline and post-donation care of donors is described. Caveats including the paired donor exchange programs and non-directed and directed donation are also considered.

Simulated and experimental evaluation of factors affecting the rate and extent of reductive dehalogenation of chloroethenes with glucose.

PubMed

Lee, Il-Su; Bae, Jae-Ho; Yang, Yanru; McCarty, Perry L

2004-10-01

Carbohydrates such as molasses are being added to aquifers to serve as electron donors for reductive dehalogenation of chloroethenes. Glucose, as a model carbohydrate, was studied to better understand the processes involved and to evaluate the effectiveness for dehalogenation of different approaches for carbohydrate addition. A simulation model was developed and calibrated with experimental data for the reductive dehalogenation of tetrachloroethene to ethene via cis-1,2-dichloroethene. The model included fermentors that convert the primary donor (glucose) into butyrate, acetate and hydrogen, methanogens, and two separate dehalogenator groups. The dehalogenation groups use the hydrogen intermediate as an electron donor and the different haloethenes as electron acceptors through competitive inhibition. Model simulations suggest first that the initial relative population size of dehalogenators and H(2)-utilizing methanogens greatly affects the degree of dehalogenation achieved. Second, the growth and decay of biomass from soluble carbohydrate plays a significant role in reductive dehalogenation. Finally, the carbohydrate delivery strategies used (periodic versus batch addition and the time interval between periodic addition) greatly affect the degree of dehalogenation that can be obtained with a given amount of added carbohydrate.

Co-fermentation of sewage sludge with ryegrass for enhancing hydrogen production: Performance evaluation and kinetic analysis.

PubMed

Yang, Guang; Wang, Jianlong

2017-11-01

The low C/N ratio and low carbohydrate content of sewage sludge limit its application for fermentative hydrogen production. In this study, perennial ryegrass was added as the co-substrate into sludge hydrogen fermentation with different mixing ratios for enhancing hydrogen production. The results showed that the highest hydrogen yield of 60mL/g-volatile solids (VS) added was achieved when sludge/perennial ryegrass ratio was 30:70, which was 5 times higher than that from sole sludge. The highest VS removal of 21.8% was also achieved when sludge/perennial ryegrass ratio was 30:70, whereas VS removal from sole sludge was only 0.7%. Meanwhile, the co-fermentation system simultaneously improved hydrogen production efficiency and organics utilization of ryegrass. Kinetic analysis showed that the Cone model fitted hydrogen evolution better than the modified Gompertz model. Furthermore, hydrogen yield and VS removal increased with the increase of dehydrogenase activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Utilization of Deceased Donor Kidneys to Initiate Living Donor Chains.

PubMed

Melcher, M L; Roberts, J P; Leichtman, A B; Roth, A E; Rees, M A

2016-05-01

We propose that some deceased donor (DD) kidneys be allocated to initiate nonsimultaneous extended altruistic donor chains of living donor (LD) kidney transplants to address, in part, the huge disparity between patients on the DD kidney waitlist and available donors. The use of DD kidneys for this purpose would benefit waitlisted candidates in that most patients enrolled in kidney paired donation (KPD) systems are also waitlisted for a DD kidney transplant, and receiving a kidney through the mechanism of KPD will decrease pressure on the DD pool. In addition, a LD kidney usually provides survival potential equal or superior to that of DD kidneys. If KPD chains that are initiated by a DD can end in a donation of an LD kidney to a candidate on the DD waitlist, the quality of the kidney allocated to a waitlisted patient is likely to be improved. We hypothesize that a pilot program would show a positive impact on patients of all ethnicities and blood types. © Copyright 2016 The American Society of Transplantation and the American Society of Transplant Surgeons.

Dynamic study of excited state hydrogen-bonded complexes of harmane in cyclohexane-toluene mixtures.

PubMed

Carmona, Carmen; Balón, Manuel; Galán, Manuel; Guardado, Pilar; Muñoz, María A

2002-09-01

Photoinduced proton transfer reactions of harmane or 1-methyl-9H-pyrido[3,4-b]indole (HN) in the presence of the proton donor hexafluoroisopropanol (HFIP) in cyclohexane-toluene mixtures (CY-TL; 10% vol/vol of TL) have been studied. Three excited state species have been identified: a 1:2 hydrogen-bonded proton transfer complex (PTC), between the pyridinic nitrogen of the substrate and the proton donor, a hydrogen-bonded cation-like exciplex (CL*) with a stoichiometry of at least 1:3 and a zwitterionic exciplex (Z*). Time-resolved fluorescence measurements evidence that upon excitation of ground state PTC, an excited state equilibrium is established between PTC* and the cationlike exciplex, CL*, lambdaem approximately/= 390 nm. This excited state reaction is assisted by another proton donor molecule. Further reaction of CL* with an additional HFIP molecule produces the zwitterionic species, Z*, lambda(em) approximately/= 500 nm. From the analysis of the multiexponential decays, measured at different emission wavelengths and as a function of HFIP concentration, the mechanism of these excited state reactions has been established. Thus, three rate constants and three reciprocal lifetimes have been determined. The simultaneous study of 1,9-dimethyl-9H-pyrido[3,4-b]indole (MHN) under the same experimental conditions has helped to understand the excited state kinetics of these processes.

Hydrogen-bonding Interactions between Apigenin and Ethanol/Water: A Theoretical Study

NASA Astrophysics Data System (ADS)

Zheng, Yan-Zhen; Zhou, Yu; Liang, Qin; Chen, Da-Fu; Guo, Rui; Lai, Rong-Cai

2016-10-01

In this work, hydrogen-bonding interactions between apigenin and water/ethanol were investigated from a theoretical perspective using quantum chemical calculations. Two conformations of apigenin molecule were considered in this work. The following results were found. (1) For apigenin monomer, the molecular structure is non-planar, and all of the hydrogen and oxygen atoms can be hydrogen-bonding sites. (2) Eight and seven optimized geometries are obtained for apigenin (I)-H2O/CH3CH2OH and apigenin (II)-H2O/CH3CH2OH complexes, respectively. In apigenin, excluding the aromatic hydrogen atoms in the phenyl substituent, all other hydrogen atoms and the oxygen atoms form hydrogen-bonds with H2O and CH3CH2OH. (3) In apigenin-H2O/CH3CH2OH complexes, the electron density and the E(2) in the related localized anti-bonding orbital are increased upon hydrogen-bond formation. These are the cause of the elongation and red-shift of the X-H bond. The sum of the charge change transfers from the hydrogen-bond acceptor to donor. The stronger interaction makes the charge change more intense than in the less stable structures. (4) Most of the hydrogen-bonds in the complexes are electrostatic in nature. However, the C4-O5···H, C9-O4···H and C13-O2···H hydrogen-bonds have some degree of covalent character. Furthermore, the hydroxyl groups of the apigenin molecule are the preferred hydrogen-bonding sites.

Donor attention to reading materials.

PubMed

O'Brien, S F; Osmond, L; Choquet, K; Yi, Q-L; Goldman, M

2015-11-01

Mandatory predonation reading materials inform donors about risk factors for transmissible disease, possible complications of donation and changes to the donation process. We aimed to assess the attention to predonation reading materials and factors which may affect attention. A national survey in 2008 of 18,108 blood donors asked about self-assessed attention to reading the materials. In face-to-face interviews, 441 donors completed additional questions about reading the materials and a literacy test. Qualitative interviews of 27 donors assessed their approach to reading. In the national survey, most of the first-time donors said they read all or most of the materials (90.9% first-time vs. 57.6% repeat donors, P < 0.001) and 66% vs. 23.1% reported reading them carefully (P < 0.001). In face-to-face interviews comparing those who read materials carefully, skimmed or did not read, most knew that donors are informed of positive transmissible disease test results (97.1%, 95.5, 98.0 P > 0.05), but fewer recalled seeing the definition of sex (77.2%, 56.9, 24.2 P < 0.001). Literacy was poor (30.5% frustration level, 60.3% instructional, 9.2% independent) but similar when those who read materials carefully, skimmed or did not read were compared (P > 0.05). Qualitative interviews showed that donors are reluctant to read any more than necessary and decide based on perceived importance or relevance. Attention to predonation reading materials tends to be better among first-time donors. The effectiveness is limited by low motivation to read, especially for repeat donors, as well as poor literacy. © 2015 International Society of Blood Transfusion.

Lung Transplantation From Donors After Previous Cardiac Surgery: Ideal Graft in Marginal Donor?

PubMed

Palleschi, A; Mendogni, P; Tosi, D; Montoli, M; Carrinola, R; Mariolo, A V; Briganti, F; Nosotti, M

2017-05-01

Lung transplantation is a limited by donor pool shortage. Despite the efforts to extend the graft acceptability with recurrent donor criteria reformulations, previous cardiothoracic surgery is still considered a contraindication. A donor who underwent cardiac surgery could potentially provide an ideal lung but high intraoperative risks and intrinsic technical challenges are expected during the graft harvesting. The purpose of this study is to present our dedicated protocol and four clinical cases of successful lung procurements from donors who had a previous major cardiac surgery. One donor had ascending aortic root (AAR) substitution, another had mitral valve substitution, and two had coronary artery bypass surgery. The others' eligibility criteria for organ allocation, such as ABO compatibility, PaO 2 /FiO 2 ratio, absence of aspiration, or sepsis were respected. In one of the cases with previous coronary bypass grafting, the donor had a veno-arterial extracorporeal membrane oxygenation support. Consequently, the grafts required an ex vivo lung perfusion evaluation. We report the technical details of procurement and postoperative courses of recipients. All procurements were uneventful, without lung damage or waste of abdominal organs related to catastrophic intraoperative events. All recipients had a successful clinical outcome. We believe that successful transplantation is achievable even in a complicated setting, such as cases involving donors with previous cardiac surgery frequently are. Facing lung donor shortage, we strongly support any effort to avoid the loss of possible acceptable lungs. In particular, previous major cardiac surgery does not strictly imply a poor quality of lungs as well as unsustainable graft procurement. Copyright © 2017 Elsevier Inc. All rights reserved.

Polymer formulations for gettering hydrogen

DOEpatents

Shepodd, Timothy J.; Even, Jr., William R.

2000-01-01

A novel method for preparing a hydrogenation composition comprising organic polymer molecules having carbon--carbon double bonds, for removing hydrogen from the atmosphere within enclosed spaces and particularly from atmospheres within enclosed spaces that contain air, water vapor, oxygen, carbon dioxide or ammonia. The organic polymers molecules containing carbon--carbon double bonds throughout their structures, preferably polybutadiene, polyisoprene and derivatives thereof, intimately mixed with an insoluble noble metal catalyst composition. High molecular weight polymers may be added to the organic polymer/catalyst mixture in order to improve their high temperature performance. The hydrogenation composition is prepared by dispersing the polymers in a suitable solvent, forming thereby a solution suspension, flash-freezing droplets of the solution in a liquid cryogen, freeze-drying the frozen droplets to remove frozen solvent incorporated in the droplets, and recovering the dried powder thus formed.

Wide-range light-harvesting donor-acceptor assemblies through specific intergelator interactions via self-assembly.

PubMed

Samanta, Suman K; Bhattacharya, Santanu

2012-12-03

We have synthesized two new low-molecular-mass organogelators based on tri-p-phenylene vinylene derivatives, one of which could be designated as the donor whereas the other one is an acceptor. These were prepared specifically to show the intergelator interactions at the molecular level by using donor-acceptor self-assembly to achieve appropriate control over their macroscopic properties. Intermolecular hydrogen-bonding, π-stacking, and van der Waals interactions operate for both the individual components and the mixtures, leading to the formation of gels in the chosen organic solvents. Evidence for intergelator interactions was acquired from various spectroscopic, microscopic, thermal, and mechanical investigations. Due to the photochromic nature of these molecules, interesting photophysical properties, such as solvatochromism and J-type aggregation, were clearly observed. An efficient energy transfer was exhibited by the mixture of donor-acceptor assemblies. An array of four chromophores was built up by inclusion of two known dyes (anthracene and rhodamine 6G) for the energy-transfer studies. Interestingly, an energy-transfer cascade was observed in the assembly of four chromophores in a particular order (anthracene-donor-acceptor-rhodamine 6G), and if one of the components was removed from the assembly the energy transfer process was discontinued. This allowed the build up of a light-harvesting process with a wide range. Excitation at one end produces an emission at the other end of the assembly. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rational Design of Porous Conjugated Polymers and Roles of Residual Palladium for Photocatalytic Hydrogen Production.

PubMed

Li, Lianwei; Cai, Zhengxu; Wu, Qinghe; Lo, Wai-Yip; Zhang, Na; Chen, Lin X; Yu, Luping

2016-06-22

Developing highly efficient photocatalyts for water splitting is one of the grand challenges in solar energy conversion. Here, we report the rational design and synthesis of porous conjugated polymer (PCP) that photocatalytically generates hydrogen from water splitting. The design mimics natural photosynthetics systems with conjugated polymer component to harvest photons and the transition metal part to facilitate catalytic activities. A series of PCPs have been synthesized with different light harvesting chromophores and transition metal binding bipyridyl (bpy) sites. The photocatalytic activity of these bpy-containing PCPs can be greatly enhanced due to the improved light absorption, better wettability, local ordering structure, and the improved charge separation process. The PCP made of strong and fully conjugated donor chromophore DBD (M4) shows the highest hydrogen production rate at ∼33 μmol/h. The results indicate that copolymerization between a strong electron donor and weak electron acceptor into the same polymer chain is a useful strategy for developing efficient photocatalysts. This study also reveals that the residual palladium in the PCP networks plays a key role for the catalytic performance. The hydrogen generation activity of PCP photocatalyst can be further enhanced to 164 μmol/h with an apparent quantum yield of 1.8% at 350 nm by loading 2 wt % of extra platinum cocatalyst.

Tuning the Hydrogen Storage in Magnesium Alloys

NASA Astrophysics Data System (ADS)

Er, Suleyman; de Wijs, Gilles A.; Brocks, Geert

2011-03-01

We investigate the hydrogen storage properties of promising magnesium alloys. Mg H2 (7.6 wt % H) would be a very useful storage material if the (de)hydrogenation kinetics can be improved and the desorption temperature is markedly lowered. Using first principles calculations, we show that hydrides of Mg-transition metal (TM) alloys adopt a structure that promotes faster (de)hydrogenation kinetics, as is also observed in experiment. Within the lightweight TMs, the most promising alloying element is titanium. Alloying Mg with Ti alone, however, is not sufficient to decrease the stability of the hydride phases, which is necessary to reduce the hydrogen desorption temperature. We find that adding aluminium or silicon markedly destabilizes Mg-Ti hydrides and stabilizes Mg-Ti alloys. Finally, we show that controlling the structure of Mg-Ti-Al(Si) system by growing it as multilayers, has a beneficial influence on the thermodynamic properties and makes it a stronger candidate for hydrogen storage.

Working with previously anonymous gamete donors and donor-conceived adults: recent practice experiences of running the DNA-based voluntary information exchange and contact register, UK DonorLink.

PubMed

Crawshaw, Marilyn; Gunter, Christine; Tidy, Christine; Atherton, Freda

2013-03-01

This article describes recent practice experiences with donor conceived adults, donors, non-donor-conceived adult children of donors using the voluntary DNA-based register, UK DonorLink. It highlights additional complexities faced when using DNA rather than paper records for searching, in particular from the risk of false positives, low chances of success and potential inclusion of biological parents' DNA. Professionals' experiences in supporting those being "linked" suggest challenges as well as rewards. Registration carries the potential to be therapeutic for donor-conceived adults and donors and to enhance their political awareness regardless of links being made. Registrants value both peer and professional support, providing the latter can respond flexibly and be delivered by staff experienced in intermediary work. Given that the majority of those affected by donor conception internationally come from anonymous donation systems, these findings are highly pertinent and argue the need for political and moral debate about such service provision.

Expanding the live kidney donor pool: ethical considerations regarding altruistic donors, paired and pooled programs.

PubMed

Patel, Shaneel Rajendra; Chadha, Priyanka; Papalois, Vassilios

2011-06-01

In renal transplant, there is a well-known deficiency in organ supply relative to demand. Live donation provides superior results when compared with deceased donation including a better rate of graft success and fewer immunologic complications. This deficiency in organs leads to significant morbidity and mortality rates. Alternative avenues have been extensively explored that may expand the live donor pool. They include altruistic donation as well as paired and pooled exchange programs. Altruistic donation is a truly selfless act from a donor unknown to the recipient. Kidney paired donation involves 2 incompatible donor-recipient pairs swapping donors to produce compatibility. Pooled donation involves at least 2 pairs, and can take the form of domino chains in which altruistic input sets up a chain of transplants, in which each recipient's incompatible donor makes a donation for the next recipient. Despite application of these various methods, there lie extensive ethical issues surrounding them. Misconceptions frequently occur; for instance, the perceived benefit that donating an organ to a loved one is greater for a related donor than for an altruistic one. Additionally, it is frequently believed that immunologic incompatibility offers coerced donors liberation from surgery, and that overcoming these barriers by introducing exchange programs provides vulnerable donors less protection. This article explores these and other complex ethical issues surrounding the various methods of expanding the donor pool. The authors offer opinions that challenge the ethical issues and attempt to overcome those views that hinder progress in the field.

Histopathologic Findings of Cholecystectomy Specimens in Patients Who Underwent Donor Hepatectomy for Living Donor Liver Transplantation.

PubMed

Akbulut, S; Karagul, S; Ertugrul, I; Aydin, C; Yilmaz, M; Yilmaz, S

2015-06-01

The aim of this study was to discuss the macroscopic and microscopic properties of gallbladder specimens obtained from living liver donors. The study retrospectively analyzed the clinical and histopathological data of 1088 donors who underwent living donor hepatectomy between March 2005 and September 2014 at Inonu University Faculty of Medicine, Liver Transplantation Center. Age, sex, macroscopic, and microscopic properties of the gallbladder (bladder length, diameter, content, and histopathological properties) were recorded by 2 researchers. A total of 1009 donors aged 17 to 66 years (31.1 ± 9.5) met the inclusion criteria, whereas 79 donors were excluded due to missing data. In total, 587 donors were male (30.5 ± 9.1 years [16-63 years]) and 422 were female (31.8 ± 9.8 years [18-66 years]). Preoperative tests revealed Gilbert syndrome in 3 subjects, whereas other donors' biochemical tests were within normal ranges. The macroscopic examination of gallbladders revealed mean gallbladder wall thickness, length, and width of 1.82 ± 0.8 mm (1-10 mm), 72 ± 11.4 mm (40-120 mm), and 52.5 ± 14 mm (15-90 mm), respectively. The microscopic gallbladder examination showed that 740 donors had a normal gallbladder, 193 had chronic cholecystitis (1 donor had antral metaplasia and 1 had intestinal metaplasia), 40 had cholesterolosis (1 donor had both tubular adenoma and intestinal metaplasia), 15 had minimal chronic cholecystitis (1 donor had pyloric metaplasia), 14 had cholelithiasis, 2 had adenomyosis, 2 had muscular hypertrophy, 1 had papillary hyperplasia, 1 had microdiverticulitis, and 1 had mucosal lymphatic ectasia. The results of this study reflect the actual gallbladder pathologies that can be detected in healthy people. Clearer conclusions can be reached about the epidemiological data on gallbladder as the number of living liver donors increases in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

Deceased donor liver transplantation from donors with central nervous system malignancy: Experience of the Inonu University.

PubMed

Ince, Volkan; Ersan, Veysel; Ozdemir, Fatih; Barut, Bora; Koc, Cemalettin; Isik, Burak; Kayaalp, Cuneyt; Yilmaz, Sezai

2017-01-01

Liver transplantation from deceased donors with a central nervous system (CNS) malignancy has some risk of tumor transmission to the recipient. Though the risk is small, this group of donors is regarded as marginal. The use of marginal grafts may be an acceptable alternative practice in order to expand the donor pool in countries where there is a shortage of donated organs. The aim of this study was to examine and present the outcomes of liver transplantations performed using donors with a CNS tumor. Between March 2002 and July 2017, 1990 (deceased donor: n=399, 20%; living donor: n=1591, 80%) liver transplantations were performed at the center. Of the 399 deceased donors, 17 (4.2%) had a CNS tumor. The data of donors with a CNS tumor and of recipients who survived for more than 1 month (n=11) were retrospectively reviewed. Demographic data, the grade of the CNS tumor, tumor transmission to recipient data, and survival rates were analyzed. Only 2 (18%) grafts were provided locally, 6 (54%) were offered to the transplantation center after all of the national centers had declined them, and 3 (37%) were made available to us by the national coordination center for patients with a documented notification of urgency. High-grade (grade III-IV) brain tumors were detected in 7 (64%) donors, while low-grade (grade I-II) tumors were found in 2 patients. The remaining 2 donors were not pathologically graded because the diagnosis was made radiologically. The 1-, 3-, and 5-year overall and tumor-free survival of the patients was estimated at 100%, 70%, and 45%, respectively. A median survival of 40 months (range: 13-62 months) was achieved in recipients of grafts from a donor with a CNS tumor and no donor-related malignant transformation was observed.

Deceased donor liver transplantation from donors with central nervous system malignancy: Experience of the Inonu University

PubMed Central

Ince, Volkan; Ersan, Veysel; Ozdemir, Fatih; Barut, Bora; Koc, Cemalettin; Isik, Burak; Kayaalp, Cuneyt; Yilmaz, Sezai

2017-01-01

OBJECTIVE: Liver transplantation from deceased donors with a central nervous system (CNS) malignancy has some risk of tumor transmission to the recipient. Though the risk is small, this group of donors is regarded as marginal. The use of marginal grafts may be an acceptable alternative practice in order to expand the donor pool in countries where there is a shortage of donated organs. The aim of this study was to examine and present the outcomes of liver transplantations performed using donors with a CNS tumor. METHODS: Between March 2002 and July 2017, 1990 (deceased donor: n=399, 20%; living donor: n=1591, 80%) liver transplantations were performed at the center. Of the 399 deceased donors, 17 (4.2%) had a CNS tumor. The data of donors with a CNS tumor and of recipients who survived for more than 1 month (n=11) were retrospectively reviewed. Demographic data, the grade of the CNS tumor, tumor transmission to recipient data, and survival rates were analyzed. RESULTS: Only 2 (18%) grafts were provided locally, 6 (54%) were offered to the transplantation center after all of the national centers had declined them, and 3 (37%) were made available to us by the national coordination center for patients with a documented notification of urgency. High-grade (grade III-IV) brain tumors were detected in 7 (64%) donors, while low-grade (grade I-II) tumors were found in 2 patients. The remaining 2 donors were not pathologically graded because the diagnosis was made radiologically. The 1-, 3-, and 5-year overall and tumor-free survival of the patients was estimated at 100%, 70%, and 45%, respectively. CONCLUSION: A median survival of 40 months (range: 13-62 months) was achieved in recipients of grafts from a donor with a CNS tumor and no donor-related malignant transformation was observed. PMID:29270568

Gamete donors' reasons for, and expectations and experiences of, registration with a voluntary donor linking register.

PubMed

Blyth, Eric; Crawshaw, Marilyn; Frith, Lucy; van den Akker, Olga

2017-12-01

This paper reports on a study of the views and experiences of 21 sperm donors and five egg donors registered with UK DonorLink (UKDL), a voluntary DNA-based contact register established to facilitate contact between adults who wish to identify and locate others to whom they are genetically related following donor conception. Specifically, the paper examines donors' reasons for searching for, or making information about themselves available to donor-conceived offspring. Their expectations of registration with UKDL, experiences of being registered and finally, the experiences of those who had contacted donor-conceived offspring and other genetic relatives are investigated. While most respondents reported largely positive experiences of registration, the study found significant issues relating to concerns about donation, DNA testing, possible linking with offspring and expectations of any relationship that might be established with offspring that have implications for support, mediation and counselling. Research that puts the experiences, perceptions and interests of gamete donors as the central focus of study is a relatively recent phenomenon. This study contributes to this debate and highlights directions for future research in this area.

Donor assists acceptor binding and catalysis of human α1,6-fucosyltransferase.

PubMed

Kötzler, Miriam P; Blank, Simon; Bantleon, Frank I; Wienke, Martin; Spillner, Edzard; Meyer, Bernd

2013-08-16

α1,6-Core-fucosyltransferase (FUT8) is a vital enzyme in mammalian physiological and pathophysiological processes such as tumorigenesis and progress of, among others, non-small cell lung cancer and colon carcinoma. It was also shown that therapeutic antibodies have a dramatically higher efficacy if the α1,6-fucosyl residue is absent. However, specific and potent inhibitors for FUT8 and related enzymes are lacking. Hence, it is crucial to elucidate the structural basis of acceptor binding and the catalytic mechanism. We present here the first structural model of FUT8 in complex with its acceptor and donor molecules. An unusually large acceptor, i.e., a hexasaccharide from the core of N-glycans, is required as minimal structure. Acceptor substrate binding of FUT8 is being dissected experimentally by STD NMR and SPR and theoretically by molecular dynamics simulations. The acceptor binding site forms an unusually large and shallow binding site. Binding of the acceptor to the enzyme is much faster and stronger if the donor is present. This is due to strong hydrogen bonding between O6 of the proximal N-acetylglucosamine and an oxygen atom of the β-phosphate of GDP-fucose. Therefore, we propose an ordered Bi Bi mechanism for FUT8 where the donor molecule binds first. No specific amino acid is present that could act as base during catalysis. Our results indicate a donor-assisted mechanism, where an oxygen of the β-phosphate deprotonates the acceptor. Knowledge of the mechanism of FUT8 is now being used for rational design of targeted inhibitors to address metastasis and prognosis of carcinomas.

Gamete donors' satisfaction; gender differences and similarities among oocyte and sperm donors in a national sample

PubMed Central

Svanberg, Agneta Skoog; Lampic, Claudia; Gejerwall, Ann-Louise; Gudmundsson, Johannes; Karlström, Per-olof; Solensten, Nils-Gunnar; Sydsjö, Gunilla

2013-01-01

ObjectiveTo explore oocyte and sperm donors' emotional stress, experiences of care and satisfaction after donation. DesignProspective multicenter study. SettingsAll fertility clinics performing gamete donation in Sweden during the period 2005 to 2008. PopulationOf 220 eligible oocyte donors who were approached, 181 agreed to complete the first questionnaire and 165 completed the second questionnaire 2 months after oocyte donation. Of 156 eligible sperm donors 119 accepted to complete the first questionnaire before donation. Eighty-nine participants completed the second questionnaire 2 months after sperm donation. MethodsStandardized and study-specific questionnaires. Main outcome measuresSatisfaction with the donation, respondents' mental health and overall care. ResultsA larger percentage of sperm donors (97.8%) were satisfied with their overall experience of being a donor than oocyte donors (85.9%, p = 0.003). Some oocyte and sperm donors did not receive sufficient information about practical issues (9.1% and 13.5%, respectively) and future consequences (12.8% and 3.4%, respectively, p = 0.014). The donors' symptoms of anxiety and depression did not show any differences in relation to negative or positive perceptions of satisfaction. The donors who did not indicate ambivalence before treatment were on average almost five times more satisfied compared with those who did indicate ambivalence (odds ratio 4.71; 95% CI 1.34–16.51). ConclusionsMost donors were satisfied with their contribution after the donation. Oocyte and sperm donors who expressed ambivalence before donation were less satisfied after donation. In vitro fertilization staff fulfilled most of the donors' needs for information and care. Please cite this article as: Skoog Svanberg A, Lampic C, Gejerwall A-L, Gudmundsson J, Karlström P-O, Solensten N-G, Sydsjö G. Gamete donors’ satisfaction; gender differences and similarities among oocyte and sperm donors in a national sample. Acta

Impact of Donor Source on the Outcome of Live Donor Kidney Transplantation: A Single Center Experience

PubMed Central

Matter, Yasser Elsayed; Nagib, Ayman M; Lotfy, Omar E; Alsayed, Ahmed Maher; Donia, Ahmed F; Refaie, Ayman F; Akl, Ahmed I; Abbas, Mohamed Hamed; Abuelmagd, Mohammed M; Shaeashaa, Hussein A; Shokeir, Ahmed A

2016-01-01

Background Renal transplantation is the ideal method for management of end-stage renal disease. The use of living donors for renal transplantation was critical for early development in the field and preceded the use of cadaveric donors. Most donors are related genetically to the recipients, like a parent, a child, or a sibling of the recipient, but there are an increasing percentage of cases where donors are genetically unrelated like spouses, friends, or altruistic individuals. Donor shortages constitute the major barrier for kidney transplantation, and much effort has been made to increase the supply of living donors. The impact of donor source on the outcome of renal transplantation is not adequately studied in our country. Objectives The aim of the study was to evaluate the impact of donor source on the outcome of live donor kidney transplantation. Patients and Methods From March 1976 to December 2013, the number of patients that underwent living renal transplantation sharing at least one HLA haplotype with their donors was 2,485. We divided these patients into two groups: (1) 2,075 kidney transplant recipients (1,554 or 74.9% male and 521 or 25.1% female) for whom the donors were living related, (2) 410 kidney transplant recipients (297 or 72.4% male and 113 or 27.6% female) for whom the donors were living unrelated. All patients received immunosuppressive therapy, consisting of a calcineurin inhibitor, mycophenolate mofetil, or azathioprine and prednisolone. We compared acute rejection and complication rates, as well as long-term graft and patient survival of both groups. Demographic characteristics were compared using the chi-square test. Graft survival and patient survival were calculated using the Kaplan-Meier method. Results The percentages of patients with acute vascular rejection were significantly higher in the unrelated group, while percentages of patients with no rejection were significantly higher in the related group, but there were no significant

Seroprevalence of Hepatitis E Virus infection among volunteer blood donors in central province of Iran in 2012

PubMed Central

Ehteram, Hassan; Ramezani, Amitis; Eslamifar, Ali; Sofian, Masoomeh; Banifazl, Mohammad; Ghassemi, Shahin; Aghakhani, Arezoo; Mashayekhi, Parisa

2013-01-01

Background and Objectives Hepatitis E virus (HEV) is a major public health concern in developing countries. HEV transmission occurs primarily by the fecal-oral route. It has also been reported that blood donors are potentially able to cause transfusion-associated hepatitis E in endemic areas. This study aimed to determine the seroprevalence of HEV infection among volunteer blood donors in Central province of Iran in 2012. Material and Methods A total of 530 consecutive blood donor samples collected from Blood Transfusion Organization, Central Province of Iran. All samples were tested for the presence of IgG Hepatitis E antibody (anti-HEV) using enzyme-linked immunosorbent assay (ELISA). Results From 530 blood donors, 91.9% were male and 8.1% were female. Overall, anti-HEV was found in 76 of 530 samples (14.3%). There was no significant difference in HEV seropositivity between the subjects regarding gender and area of residence (urban vs. rural). Anti-HEV was distributed among all age groups. Although people aged 31-50 years had the highest prevalence, but there was no statistical difference between the age groups. Conclusion This study shows a relatively high prevalence of anti-HEV in the blood donors of Central province of Iran. More investigations are needed to assess the potential benefit of adding HEV screening of blood products to the current blood donor selection criteria. PMID:23825737

Impact of Graft Selection on Donor and Recipient Outcomes After Living Donor Liver Transplantation.

PubMed

Braun, Hillary J; Dodge, Jennifer L; Roll, Garrett R; Freise, Chris E; Ascher, Nancy L; Roberts, John P

2016-06-01

Balancing donor and recipient risks in living donor liver transplantation remains an issue of debate. This study assessed the impact of graft selection on outcomes and complications for left lobe (LL) versus right lobe (RL) donors and recipients. The medical records of donors and recipients, who underwent living donor liver transplantation at our institution between 2003 and 2015, were reviewed. For donors, we evaluated graft volume, residual liver volume per standard liver volume, length of hospital stay (LOS), complications, and readmissions. For recipients, we looked at graft and patient survival, graft function at postoperative days 7 and 14, graft volume, LOS, biliary complications, Model for End-Stage Liver Disease at transplant, and hepatitis C virus status. At 5 years posttransplant, there were no significant differences in graft survival for LL recipients (86% [95% confidence interval, 74-93]) compared with 82% (95% confidence interval, 69-89) for RL recipients (P = 0.85) or recipient survival (90% vs 84%; P = 0.44). In LL recipients, postoperative days 7 and 14 median international normalized ratio (1.5 and 1.2, respectively) and total bilirubin (4.6 and 2.7) were significantly greater compared with RL recipients (7 and 14 days international normalized ratio [1.2, P < 0.001; 1.1, P = 0.001] and total bilirubin (2.7, P = 0.001; 2.1, P = 0.05)). The LL recipients also had a significantly greater median LOS (14 vs 10, P = 0.008). Median donor LOS was significantly greater for RL donors (7 [interquartile range, 7-8] vs 7 [interquartile range, 6-7] days, P < 0.001). The RL and LL grafts provide comparable long-term outcomes in properly selected donor-recipient pairs and the appropriate use of LL grafts does not impact graft or patient survival at 5 years posttransplant.

Being a haematopoietic stem cell donor for a sick sibling: Adult donors' experiences prior to donation.

PubMed

Kisch, Annika; Bolmsjö, Ingrid; Lenhoff, Stig; Bengtsson, Mariette

2015-10-01

There is a lack of knowledge about sibling stem cell donors' experiences pre-donation and the waiting period before the donation might have been long. The donors and their corresponding sibling recipients were simultaneously included in two different interview studies. The results from the recipient study have been presented in a separate paper. The aim was to explore the experiences of being a stem cell donor for a sibling, prior to donation. Ten adult sibling donors were interviewed prior to stem cell donation. The interviews were digitally recorded, transcribed verbatim and subjected to qualitative content analysis. The main theme Being a cog in a big wheel describes the complex process of being a sibling donor prior to donation, covering a mixture of emotions and thoughts. The four subthemes Being available, Being anxious, Being concerned and Being obliged cover the various experiences. The sibling donors' experiences are influenced by the quality of the relationship with the sick sibling. Sibling stem cell donors go through a complex process once they have accidentally got involved in. They have been asked to become a donor; it was not a voluntary choice. In caring for sibling stem cell donors the nurses should be aware of the complexity of the process they experience and take into consideration their personal situation and needs. Providing optimal care for both sibling donors and their corresponding recipients is a challenge, and further improvement and exploration are needed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of organ-specific donor risk indices.

PubMed

Akkina, Sanjeev K; Asrani, Sumeet K; Peng, Yi; Stock, Peter; Kim, W Ray; Israni, Ajay K

2012-04-01

Because of the shortage of deceased donor organs, transplant centers accept organs from marginal deceased donors, including older donors. Organ-specific donor risk indices have been developed to predict graft survival with various combinations of donor and recipient characteristics. Here we review the kidney donor risk index (KDRI) and the liver donor risk index (LDRI) and compare and contrast their strengths, limitations, and potential uses. The KDRI has a potential role in developing new kidney allocation algorithms. The LDRI allows a greater appreciation of the importance of donor factors, particularly for hepatitis C virus-positive recipients; as the donor risk index increases, the rates of allograft and patient survival among these recipients decrease disproportionately. The use of livers with high donor risk indices is associated with increased hospital costs that are independent of recipient risk factors, and the transplantation of livers with high donor risk indices into patients with Model for End-Stage Liver Disease scores < 15 is associated with lower allograft survival; the use of the LDRI has limited this practice. Significant regional variations in donor quality, as measured by the LDRI, remain in the United States. We also review other potential indices for liver transplantation, including donor-recipient matching and the retransplant donor risk index. Although substantial progress has been made in developing donor risk indices to objectively assess donor variables that affect transplant outcomes, continued efforts are warranted to improve these indices to enhance organ allocation policies and optimize allograft survival. Copyright © 2012 American Association for the Study of Liver Diseases.

Results of liver transplantation from old donors.

PubMed

Dudek, K; Kornasiewicz, O; Remiszewski, P; Zieniewicz, K; Wróblewski, T; Krawczyk, M

2014-10-01

Faced with a shortage of organs for liver transplantation, the use of grafts from older donors is justified. However, there remains little consensus on how this use impacts the graft and patient outcomes after transplantation from these older donors. The aim of the present analysis was to assess the graft and patient outcomes after liver transplantation from deceased donors >60 years of age. From January 2007 to January 2011, 505 subjects were identified as liver graft donors after brain death, of which 7.35% were ≥60. To determine the effect of donor age on graft and patient outcomes, we analyzed donor age, recipient age, the Model for End-State Liver Disease (MELD) score of recipients at the time of transplantation, early posttransplant complications, and mortality. The posttransplant follow-up was 29 ± 25.5 months, and 3-year patient mortality from donors, grouped according to age, was 7.92% with donors <30; 15.78% with donors 30-50, 10.68% with donors 50-60, and 12.50% with donors >60. After analysis of patient and graft survival based on donor graft age, 3-year patient survival according donor age was 89.29% with donors <30, 83.85% with donors 30-50, 89.89% with donors 50-60, and 87.50% with donors >60. Analysis showed overall patient and graft survival rates from older donors were not worse than those from younger donors (P > .1). Among the cases, 3-year patient survival according to MELD score was 91.19% with a MELD of I, 85.37% with a MELD of II, and 67.67% with a MELD of III; differences in graft and patient survival when comparing low MELD I and high MELD III were significantly different (P < .01). A more advanced age of a donor should not be a contraindication for liver transplantation. The present analysis shows that liver grafts from donors >60 can be used safely in older recipients who presented with relatively low MELD scores. Analyses also indicate that high MELD obtained before transplantation may be an important prognostic factor for graft and

The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

NASA Astrophysics Data System (ADS)

Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

2016-09-01

We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

Hydrogen-bond landscapes, geometry and energetics of squaric acid and its mono- and dianions: a Cambridge Structural Database, IsoStar and computational study.

PubMed

Allen, Frank H; Cruz-Cabeza, Aurora J; Wood, Peter A; Bardwell, David A

2013-10-01

As part of a programme of work to extend central-group coverage in the Cambridge Crystallographic Data Centre's (CCDC) IsoStar knowledge base of intermolecular interactions, we have studied the hydrogen-bonding abilities of squaric acid (H2SQ) and its mono- and dianions (HSQ(-) and SQ(2-)) using the Cambridge Structural Database (CSD) along with dispersion-corrected density functional theory (DFT-D) calculations for a range of hydrogen-bonded dimers. The -OH and -C=O groups of H2SQ, HSQ(-) and SQ(2-) are potent donors and acceptors, as indicated by their hydrogen-bond geometries in available crystal structures in the CSD, and by the attractive energies calculated for their dimers with acetone and methanol, which were used as model acceptors and donors. The two anions have sufficient examples in the CSD for their addition as new central groups in IsoStar. It is also shown that charge- and resonance-assisted hydrogen bonds involving H2SQ and HSQ(-) are similar in strength to those made by carboxylate COO(-) acceptors, while hydrogen bonds made by the dianion SQ(2-) are somewhat stronger. The study reinforces the value of squaric acid and its anions as cocrystal formers and their actual and potential importance as isosteric replacements for carboxylic acid and carboxylate functions.

Donor conversion and procurement failure: the fate of our potential organ donors.

PubMed

Branco, Bernardino C; Inaba, Kenji; Lam, Lydia; Salim, Ali; Barmparas, Galinos; Teixeira, Pedro G R; Talving, Peep; Demetriades, Demetrios

2011-02-01

Donor availability remains the primary limiting factor for organ transplantation today. The purpose of this study was to examine the causes of procurement failure amongst potential organ donors. After Institutional Review Board approval, all surgical intensive care unit (SICU) patients admitted to the LAC+USC Medical Center from 01/2006 to 12/2008 who became potential organ donors were identified. Demographics, clinical data, and procurement data were abstracted. In non-donors, the causes of procurement failure were documented. During the 3-year study period, a total of 254 patients were evaluated for organ donation. Mean age was 44.8±18.7 years; 191 (75.2%) were male, 136 (53.5%) were Hispanic, and 148 (58.3%) were trauma patients. Of the 254 patients, 116 (45.7%) were not eligible for donation: 34 had multi-system organ failure, 24 did not progress to brain death and had support withdrawn, 18 had uncontrolled sepsis, 15 had malignancy, 6 had human immunodeficiency virus or hepatitis B or C, and 19 patients had other contraindications to organ donation. Of the remaining 138 eligible patients, 83 (60.2%) did not donate: 56 because the family denied consent, 9 by their own choice. In six, next of kin could not be located, five died because of hemodynamic instability before organ procurement was possible, four had organs that could not be placed, and three had their organs declined by the organ procurement organization. The overall consent rate was 57.5% (n=67). From the 55 donors, 255 organs were procured (yield 4.6 organs/donor). Of all patients screened for organ donation, only a fifth actually donated. Denial of consent was the major potentially preventable cause of procurement failure, whereas hemodynamic instability accounted for only a small percentage of donor losses. With such low conversion rates, the preventable causes of procurement failure warrant further study.

Photoinduced Intramolecular Bifurcate Hydrogen Bond: Unusual Mutual Influence of the Components.

PubMed

Sigalov, Mark V; Shainyan, Bagrat A; Sterkhova, Irina V

2017-09-01

A series of 7-hydroxy-2-methylidene-2,3-dihydro-1H-inden-1-ones with 2-pyrrolyl (3), 4-dimethylaminophenyl (4), 4-nitrophenyl (5), and carboxyl group (6) as substituents at the exocyclic double bond was synthesized in the form of the E-isomers (4-6) or predominantly as the Z-isomer (3) which in solution is converted to the E-isomer. The synthesized compounds and their model analogues were studied by NMR spectroscopy, X-ray analysis, and MP2 theoretical calculations. The E-isomers having intramolecular O-H···O═C hydrogen bond are converted by UV irradiation to the Z-isomers having bifurcated O-H···O···H-X hydrogen bond. Unexpected shortening (and, thus, strengthening) of the O-H···O═C component of the bifurcated hydrogen bond upon the formation of the C═O···H-X hydrogen bond was found experimentally, proved theoretically (MP2), and explained by a roundabout interaction of the H-donor (HX) and H-acceptor (C═O) via the system of conjugated bonds.

Hydrogen-bonded side chain liquid crystalline block copolymer: Molecular design, synthesis, characterization and applications

NASA Astrophysics Data System (ADS)

Chao, Chi-Yang

Block copolymers can self-assemble into highly regular, microphase-separated morphologies with dimensions at nanometer length scales. Potential applications such as optical wavelength photonic crystals, templates for nanolithographic patterning, or nanochannels for biomacromolecular separation take advantage of the well-ordered, controlled size microdomains of block copolymers. Side-chain liquid crystalline block copolymers (SCLCBCPs) are drawing increasing attention since the incorporation of liquid crystallinity turns their well-organized microstructures into dynamic functional materials. As a special type of block copolymer, hydrogen-bonded SCLCBCPs are unique, compositionally tunable materials with multiple dynamic functionalities that can readily respond to thermal, electrical and mechanical fields. Hydrogen-bonded SCLCBCPs were synthesized and assembled from host poly(styrene- b-acrylic acid) diblock copolymers with narrow molecular weight distributions as proton donors and guest imidazole functionalized mesogenic moieties as proton acceptors. In these studies non-covalent hydrogen bonding is employed to connect mesogenic side groups to a block copolymer backbone, both for its dynamic character as well as for facile materials preparation. The homogeneity and configuration of the hydrogen-bonded complexes were determined by both the molecular architecture of imidazolyl side groups and the process conditions. A one-dimensional photonic crystal composed of high molecular weight hydrogen-bonded SCLCBCP, with temperature dependent optical wavelength stop bands was successfully produced. The microstructures of hydrogen-bonded complexes could be rapidly aligned in an AC electric field at temperatures below the order-disorder transition but above their glass transitions. Remarkable dipolar properties of the mesogenic groups and thermal dissociation of hydrogen bonds are key elements to fast orientation switching. Studies of a wide range of mesogen and polymer

The personality and motivation of semen donors: a comparison with oocyte donors.

PubMed

Schover, L R; Rothmann, S A; Collins, R L

1992-04-01

Seventeen consecutively recruited candidates for semen donation were evaluated by a psychologist with testing and a structured interview. Most men (71%) were motivated by financial compensation. Only 29% would donate semen if records were open to potential offspring. Fifty-nine per cent of the men were rated as excellent candidates from a psychological perspective and 35% were rated as acceptable with slight reservations. One was excluded as a donor. Psychological testing revealed mildly abnormal subscale scores for 35% of donors. Forty-seven per cent had histories of minor depressive or anxiety episodes and 35% had had periods of heavy alcohol use. Compared to oocyte donors at the same institution, the men were less altruistic, more affluent, and more likely to have abused alcohol. Women had more traumatic family and reproductive histories. Psychological evaluation can be a valuable tool in gamete donor selection.

Achieving donor repetition and motivation by block leaders among current blood donors.

PubMed

Martín-Santana, Josefa D; Beerli-Palacio, Asunción

2012-12-01

This paper presents an explicative model on the recommendation of donating blood made to relatives and friends by current donors. This model establishes satisfaction and intention to return as direct antecedents, and the quality perceived in the donation process and the existence of inhibitors as indirect antecedents. The results show that (1) the perceived quality has a positive influence on satisfaction and intention to return; (2) the intention to donate again depends positively on satisfaction, but negatively on the existence of internal and external inhibitors; and lastly (3) the recommendation to donate depends on donor satisfaction and their intention to return to donate, this being the most influential factor. At the same time, we contrasted how the model does not vary, whether it is a first-time donor or a repeat donor. Copyright © 2012 Elsevier Ltd. All rights reserved.

Hydrogen peroxide stabilization in one-dimensional flow columns

NASA Astrophysics Data System (ADS)

Schmidt, Jeremy T.; Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

2011-09-01

Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H 2O 2 propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.

Philanthropic Motivations of Community College Donors

ERIC Educational Resources Information Center

Carter, Linnie S.; Duggan, Molly H.

2011-01-01

This descriptive study surveyed current, lapsed, and major gift donors to explore the impact of college communications on donors' decisions to contribute to the college, the likelihood of donor financial support for various college projects, and the philanthropic motivation profiles of the donors of a midsized, multicampus community college in…

Fear, fascination and the sperm donor as 'abjection' in interviews with heterosexual recipients of donor insemination.

PubMed

Burr, Jennifer

2009-07-01

The background to this article is the medical regulation of sperm donation in the UK and the recent policy change so that children born from sperm, eggs or embryos donated after April 2005 have the right to know their donor's identity. I draw upon data from interviews with ten women and seven joint interviews with couples who received donor insemination from an anonymous sperm donor and were the parents of donor insemination children. I explore the symbolic presence of the donor and his potential to disrupt social and physical boundaries using the theoretical conceptions of boundaries and pollution as articulated by Mary Douglas and Julia Kristeva. I present data to argue that the anonymous donor manifests in various figures; the shadowy and ambiguous figure of 'another man'; the intelligent medical student; the donor as a family man, with children of his own who wants to help infertile men father children. In addition participants perceive the donor's physical characteristics, but also see their husband's physical characteristics, in their children. In conclusion I argue that anonymisation preserves features of conventional family life, maintains the idea of exclusivity within the heterosexual relationship and affirms the legal father's insecurity about his infertility.

Synthesis and photoluminescence properties of silver(I) complexes based on N-benzoyl-L-glutamic acid and N-donor ligands with different flexibility

NASA Astrophysics Data System (ADS)

Yan, Ming-Jie; Feng, Qi; Song, Hui-Hua

2016-05-01

By changing the N-donor ancillary ligand, three novel silver (I) complexes {[Ag(HbzgluO) (4,4‧-bipy)]·H2O}n (1), {[Ag2(HbzgluO)2 (bpe)2]·2H2O}n (2) and {[Ag(HbzgluO)(bpp)]·2H2O}n (3) (H2bzgluO = N-benzoyl-L-glutamic acid, 4,4‧-bipy = 4,4ˊ-bipyridine, bpe = 1,2-di(4-pyridyl)ethane, bpp = 1,3-di(4-pyridyl)propane) were synthesized. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). In this study, the N-donor ligands are changed from rigidity (4,4‧-bipy), quasi-flexibility (bpe) to flexibility (bpp), the structures of complexes also change. Complex 1 features a 1D chain structure which is further linked together to construct a 2D supramolecular structure through hydrogen bonds. Complex 2 is a 1D double-chains configuration which eventually forms a 3D supramolecular network via hydrogen bonding interactions. Whereas, complex 3 exhibits a 2D pleated grid structure which is linked by hydrogen bonding interactions into a 3D supramolecular network. The present observations demonstrate that the modulation of coordination polymers with different structures can accomplish by changing the spacer length of N-donor ligands. In addition, the solid-state circular dichroism (CD) spectra indicated that compound 2 exhibited negative cotton effect which originated from the chiral ligands H2bzgluO and the solid-state fluorescence spectra of the three complexes demonstrated the auxiliary ligands have influence on the photoluminescence properties of the complexes.

Supramolecular hydrogen-bonding patterns in 1:1 cocrystals of 5-fluorouracil with 4-methylbenzoic acid and 3-nitrobenzoic acid.

PubMed

Mohana, Marimuthu; Muthiah, Packianathan Thomas; McMillen, Colin D

2017-03-01

The design of a pharmaceutical cocrystal is based on the identification of specific hydrogen-bond donor and acceptor groups in active pharmaceutical ingredients (APIs) in order to choose a `complementary interacting' molecule that can act as an efficient coformer. 5-Fluorouracil (5FU) is a pyrimidine derivative with two N-H donors and C=O acceptors and shows a diversity of hydrogen-bonding motifs. Two 1:1 cocrystals of 5-fluorouracil (5FU), namely 5-fluorouracil-4-methylbenzoic acid (5FU-MBA), C 4 H 3 FN 2 O 2 ·C 8 H 8 O 2 , (I), and 5-fluorouracil-3-nitrobenzoic acid (5FU-NBA), C 4 H 3 FN 2 O 2 ·C 7 H 5 NO 4 , (II), have been prepared and characterized by single-crystal X-ray diffraction. In (I), the MBA molecules form carboxylic acid dimers [R 2 2 (8) homosynthon]. Similarly, the 5FU molecules form two types of base pair via a pair of N-H...O hydrogen bonds [R 2 2 (8) homosynthon]. In (II), 5FU interacts with the carboxylic acid group of NBA via N-H...O and O-H...O hydrogen bonds, generating an R 2 2 (8) ring motif (heterosynthon). Furthermore, the 5FU molecules form base pairs [R 2 2 (8) homosynthon] via N-H...O hydrogen bonds. Both of the crystal structures are stabilized by C-H...F interactions.

Individual, contextual and network characteristics of blood donors and non-donors: a systematic review of recent literature

PubMed Central

Piersma, Tjeerd W.; Bekkers, René; Klinkenberg, Elisabeth F.; de Kort, Wim L.A.M.; Merz, Eva-Maria

2017-01-01

Background The ageing population and recent migration flows may negatively affect the blood supply in the long term, increasing the importance of targeted recruitment and retention strategies to address donors. This review sought to identify individual, network and contextual characteristics related to blood donor status and behaviour, to systematically discuss differences between study results, and to identify possible factors to target in recruitment and retention efforts. Methods The systematic review was conducted in accordance with a predefined PROSPERO protocol (CRD42016039591). After quality assessments by multiple independent raters, a final set of 66 peer-reviewed papers, published between October 2009 and January 2017, were included for review. Results Individual and contextual characteristics of blood donor status and behaviour were categorised into five main lines of research: donor demographics, motivations and barriers, adverse reactions and deferral, contextual factors, and blood centre factors. Results on donor demographics, motivations and barriers, and contextual factors were inconclusive, differing between studies, countries, and sample characteristics. Adverse reactions and deferral were negatively related to blood donor behaviour. Blood centre factors play an important role in donor management, e.g., providing information, reminders, and (non-)monetary rewards. No studies were found on network characteristics of (non-)donors. Discussion Although individual and contextual characteristics strongly relate to blood donor status and behaviour, mechanisms underlying these relations have not been studied sufficiently. We want to stress the importance of longitudinal studies in donor behaviour, exploring the role of life events and network characteristics within blood donor careers. Increased understanding of donor behaviour will assist policy makers of blood collection agencies, with the ultimate goal of safeguarding a sufficient and matching blood

Individual, contextual and network characteristics of blood donors and non-donors: a systematic review of recent literature.

PubMed

Piersma, Tjeerd W; Bekkers, René; Klinkenberg, Elisabeth F; De Kort, Wim L A M; Merz, Eva-Maria

2017-09-01

The ageing population and recent migration flows may negatively affect the blood supply in the long term, increasing the importance of targeted recruitment and retention strategies to address donors. This review sought to identify individual, network and contextual characteristics related to blood donor status and behaviour, to systematically discuss differences between study results, and to identify possible factors to target in recruitment and retention efforts. The systematic review was conducted in accordance with a predefined PROSPERO protocol (CRD42016039591). After quality assessments by multiple independent raters, a final set of 66 peer-reviewed papers, published between October 2009 and January 2017, were included for review. Individual and contextual characteristics of blood donor status and behaviour were categorised into five main lines of research: donor demographics, motivations and barriers, adverse reactions and deferral, contextual factors, and blood centre factors. Results on donor demographics, motivations and barriers, and contextual factors were inconclusive, differing between studies, countries, and sample characteristics. Adverse reactions and deferral were negatively related to blood donor behaviour. Blood centre factors play an important role in donor management, e.g., providing information, reminders, and (non-)monetary rewards. No studies were found on network characteristics of (non-)donors. Although individual and contextual characteristics strongly relate to blood donor status and behaviour, mechanisms underlying these relations have not been studied sufficiently. We want to stress the importance of longitudinal studies in donor behaviour, exploring the role of life events and network characteristics within blood donor careers. Increased understanding of donor behaviour will assist policy makers of blood collection agencies, with the ultimate goal of safeguarding a sufficient and matching blood supply.

Potential application of anaerobic extremophiles for hydrogen production

NASA Astrophysics Data System (ADS)

Pikuta, Elena V.; Hoover, Richard B.

2004-11-01

In processes of the substrate fermentation most anaerobes produce molecular hydrogen as a waste end product, which often controls the culture growth as an inhibitor. Usually in nature the hydrogen is easily removed from an ecosystem, due to its physical features, and an immediate consumption by the secondary anaerobes that sometimes behave as competitors for electron donors; a classical example of this kind of substrate competition in anaerobic microbial communities is the interaction between methanogens and sulfate- or sulfur-reducers. Previously, on the mixed cultures of anaerobes at neutral pH, it was demonstrated that bacterial hydrogen production could provide a good alternative energy source. At neutral pH the original cultures could easily contaminated by methanogens, and the most unpleasant side effect of these conditions is the development of pathogenic bacteria. In both cases the rate of hydrogen production was dramatically decreased since some part of the hydrogen was transformed to methane, and furthermore, the cultivation with pathogenic contaminants on an industrial scale would create an unsafe situation. In our laboratory the experiments with obligately alkaliphilic bacteria producing hydrogen as an end metabolic product were performed at different conditions. The mesophilic, haloalkaliphilic and obligately anaerobic bacterium Spirochaeta americana ASpG1T was studied and various cultivation regimes were compared for the most effective hydrogen production. In a highly mineralized media with pH 9.5-10.0 not many known methanogens are capable of growth, and the probability of developing pathogenic contaminants is theoretically is close to zero (in medicine carbonate- saturated solutions are applied as antiseptics). Therefore the cultivation of alkaliphilic hydrogen producing bacteria could be considered as a safe and economical process for large-scale industrial bio-hydrogen production in the future. Here we present and discuss the experimental data

Diaphragmatic herniation following donor hepatectomy for living donor liver transplantation: a serious complication not given due recognition.

PubMed

Lochan, Rajiv; Saif, Rehan; Ganjoo, Naveen; Sakpal, Mallikarjun; Panackal, Charles; Raja, Kaiser; Reddy, Jayanth; Asthana, Sonal; Jacob, Mathew

2017-11-01

A clear appreciation of benefits and risks associated with living donor hepatectomy is important to facilitate counselling for the donor, family, and recipient in preparation for living donor liver transplant (LDLT). We report a life-threatening complication occurring in one of our live liver donors at 12 weeks following hemi-liver donation. We experienced five donor complications among our first 50 LDLT: Clavien Grade 1, n=1; Clavien grade 2, n=3; and Clavien grade 3B, n=1. The one with Clavien grade 3B had a life-threatening diaphragmatic hernia occurring 12 weeks following hepatectomy. This was promptly recognized and emergency surgery was performed. The donor is well at 1-year follow-up. Here we provide a review of reported instances of diaphragmatic hernia following donor hepatectomy with an attempt to elucidate the pathophysiology behind such occurrence. Life-threatening donor risk needs to be balanced with recipient benefit and risk on a tripartite basis during the counselling process for LDLT. With increasing use of LDLT, we need to be aware of such life-threatening complication. Preventive measures in this regard and counselling for such complication should be incorporated into routine work-up for potential live liver donor.

Laparoscopic donor nephrectomy increases the supply of living donor kidneys: a center-specific microeconomic analysis.

PubMed

Kuo, P C; Johnson, L B

2000-05-27

A tenet of microeconomics is that new technology will shift the supply curve to the right. Laparoscopic donor nephrectomy (LDN) is a new technique for removal of living donor kidneys. Centers performing this procedure have noted an increased number of patients presenting for donor evaluation. This has not been previously studied. The records of all LDN performed from May 1998 to February 1999 were reviewed. The following variables were examined: sex, age, related vs. unrelated donation, estimated blood loss, i.v. analgesia, length of stay, and time out of work. Donors undergoing traditional open donor nephrectomy during January 1997 to May 1998 served as the control group. A composite cost index was constructed. LDN significantly decreased length of stay, pain, and time out of work; the supply function shifted to the right. Telephone interviews revealed that 47% donated solely because of the LDN procedure. LDN increases the supply of living donor kidneys.

Hydrogen bonded C-H···Y (Y = O, S, Hal) molecular complexes: A natural bond orbital analysis

NASA Astrophysics Data System (ADS)

Isaev, A. N.

2016-03-01

Hydrogen bonded C-H···Y complexes formed by H2O, H2S molecules, hydrogen halides, and halogen-ions with methane, halogen substituted methane as well as with the C2H2 and NCH molecules were studied at the MP2/aug-cc-pVDZ level. The structure of NBOs corresponding to lone pair of acceptor Y, n Y, and vacant anti-σ-bond C-H of proton donor was analyzed and estimates of second order perturbation energy E(2) characterizing donor-acceptor n Y → σ C-H * charge-transfer interaction were obtained. Computational results for complexes of methane and its halogen substituted derivatives show that for each set of analogous structures, the EnY→σ*C-H (2) energy tends to grow with an increase in the s-component percentage in the lone pair NBO of acceptor Y. Calculations for different C···Y distances show that the equilibrium geometries of complexes lie in the region where the E(2) energy is highest and it changes symbatically with the length of the covalent E-H bond when the R(C···Y) distance is varied. The performed analysis allows us to divide the hydrogen bonded complexes into two groups, depending on the pattern of overlapping for NBOs of the hydrogen bridge.

Hydrogen production by a thermophilic blue-green alga Mastigocladus laminosus

NASA Astrophysics Data System (ADS)

Miura, Y.; Yokoyama, H.; Miyamoto, K.; Okazaki, M.; Komemushi, S.

Light-driven hydrogen evolution by a thermophilic blue-green alga, Mastigocladus laminosus, was demonstrated and characterized under nitrogen-starved conditions. Air-grown cultures of this alga evolved hydrogen under Ar/CO2 at rates up to 2.2 ml/mg chl/hr. The optimum temperature and pH for the hydrogen evolution were 44-49 C and pH 7.0-7.5, respectively. Evolution in light was depressed by N2 gas and inhibited by salicylaldoxime or 2,4-dinitrophenol, indicating that nitrogenase was mainly responsible for the hydrogen evolution. The evolution rate was improved by adding carbon monoxide and acetylene to the gas phase of Ar/CO2. In addition, photobiological production of hydrogen (biophotolysis) by various blue-green algae is briefly reviewed and discussed.

Successful haploidentical donor hematopoietic stem cell transplant and restoration of STAT3 function in an adolescent with autosomal dominant hyper-IgE syndrome.

PubMed

Patel, N C; Gallagher, J L; Torgerson, T R; Gilman, A L

2015-07-01

Autosomal dominant hyper-IgE syndrome (AD-HIES), caused by mutations in Signal Transducer and Activator of Transcription 3 (STAT3) is associated with defective STAT3 signaling and Th17 differentiation and recurrent bacterial and fungal infections. Most patients suffer significant morbidity and premature mortality. Hematopoietic stem cell transplantation (HSCT) has been reported in a small number of cases, with mixed outcomes. We report successful haploidentical donor HSCT in a patient with AD-HIES. Evaluation of lymphocyte subsets, STAT3 signaling, and Th17 cells was performed pre- and post-HSCT. A 14-year old female with AD-HIES developed recurrent methicillin-resistant Staphylococcus aureus (MRSA) abscesses. Immunologic analysis showed elevated IgE (4331 kU/L), absent Th17 cells, and markedly decreased STAT3 phosphorylation in cytokine stimulated peripheral blood mononuclear cells. She had breakthrough abscesses despite clindamycin and trimethoprim-sulfamethoxazole prophylaxis, and developed steroid refractory autoimmune hemolytic anemia. She underwent T-cell depleted haploidentical HSCT from her father following reduced intensity conditioning. She developed one MRSA hand abscess after transplant. Twenty-four months post transplant, she had complete donor chimerism (>95 % donor), normal absolute T cell numbers, and a normal percentage of Th17 cells. IgE was normal at 25 kU/L. She remains well 42 months after transplantation off all antibacterial prophylaxis. Haploidentical HSCT led to successful bone marrow engraftment, normalization of STAT3 signaling in hematopoietic cells, normalization of IgE, and restoration of immune function in this patient with AD-HIES.

Mixed oxide nanoparticles and method of making

DOEpatents

Lauf, Robert J.; Phelps, Tommy J.; Zhang, Chuanlun; Roh, Yul

2002-09-03

Methods and apparatus for producing mixed oxide nanoparticulates are disclosed. Selected thermophilic bacteria cultured with suitable reducible metals in the presence of an electron donor may be cultured under conditions that reduce at least one metal to form a doped crystal or mixed oxide composition. The bacteria will form nanoparticles outside the cell, allowing easy recovery. Selection of metals depends on the redox potentials of the reducing agents added to the culture. Typically hydrogen or glucose are used as electron donors.

Hydrogen-bonding interactions between a nitrile-based functional ionic liquid and DMSO

NASA Astrophysics Data System (ADS)

Zheng, Yan-Zhen; Zhou, Yu; Deng, Geng; Yu, Zhi-Wu

2016-11-01

Task-specific ionic liquids (TSILs) have been introduced by incorporating additional functional groups in the cation or anion to impart specific properties or reactivates. In this work, the hydrogen-bonding interactions between a nitrile-functional TSIL 1-propylnitrile-3-methylimidazolium tetrafluoroborate ([PCNMIM][BF4]) and dimethyl sulphoxide (DMSO) were investigated in detail by attenuated total reflection infrared spectroscopy (ATR-IR), combined with hydrogen nuclear magnetic resonance (1H NMR) and density functional theory calculations (DFT). It was found that, first, introducing a nitrile group into the alkyl chain does not change the main interaction site in the cation. It is still the C2 hydrogen. So the v(C2-H) is more sensitive to the environmental change and can be used as an indicator of the environments change of IL. Second, the wavenumber shift changes of v(C2-H) have two turning points (xDMSO ≈ 0.6 and 0.9), dividing the dilution process into three stages. Combined with the calculation results, the dilution process is identified as: From larger ion clusters to smaller ion clusters (xDMSO < 0.6), then to ion pairs (0.6 0.9). Introducing a nitrile group into the alkyl chain does not influence the dilution process of IL dissolving in DMSO. Third, the Ctbnd N in [PCNMIM][BF4] can work as an electron donor in forming hydrogen-bonds with the methyl group of [PCNMIM]+ and DMSO, but its strength is weaker than that formed by the imidazolium ring C-Hs. The dual roles of the cation to work as both electron acceptor and donor expand the wide applications of this nitrile-functional ionic liquid.

Active Donor Management During the Hospital Phase of Care Is Associated with More Organs Transplanted per Donor.

PubMed

Patel, Madhukar S; De La Cruz, Salvador; Sally, Mitchell B; Groat, Tahnee; Malinoski, Darren J

2017-10-01

Meeting donor management goals when caring for potential organ donors has been associated with more organs transplanted per donor (OTPD). Concern persists, however, as to whether this indicates that younger/healthier donors are more likely to meet donor management goals or whether active management affects outcomes. A prospective observational study of all standard criteria donors was conducted by 10 organ procurement organizations across United Network for Organ Sharing Regions 4, 5, and 6. Donor management goals representing normal critical care end points were measured at 2 time points: when a catastrophic brain injury was recognized and a referral was made to the organ procurement organization by the DH; and after brain death was declared and authorization for organ donation was obtained. Donor management goals Bundle "met" was defined as achieving any 7 of 9 end points. A positive Bundle status change was defined as not meeting the Bundle at referral and subsequently achieving it at authorization. The primary outcomes measure was having ≥4 OTPD. Data were collected for 1,398 standard criteria donors. Of the 1,166 (83%) who did not meet the Bundle at referral, only 254 (22%) had a positive Bundle status change. On adjusted analysis, positive Bundle status change increased the odds of achieving ≥4 OTPD significantly (odds ratio 2.04; 95% CI 1.49 to 2.81; p < 0.001). A positive donor management goal Bundle status change during donor hospital management is associated with a 2-fold increase in achieving ≥4 OTPD. Active critical care management of the potential organ donor, as evidenced by improvement in routinely measured critical care end points can be a means by which to substantially increase the number of organs available for transplantation. Published by Elsevier Inc.

Octogenarian Donors in Liver Transplantation.

PubMed

Gastaca, M; Guerra, M; Alvarez Martinez, L; Ruiz, P; Ventoso, A; Palomares, I; Prieto, M; Matarranz, A; Valdivieso, A; Ortiz de Urbina, J

2016-11-01

Due to the disparity between the number of patients on the list for liver transplantation and the availability of organs, the use of older donors has become necessary. The aim of this study was to investigate the outcomes of liver transplantation using octogenarian donors. From December 2003 to February 2016, 777 liver transplantations were performed at our institution, 33 of them (4.2%) with donors 80 years old and above. Our policy for the acceptance of these donors is based on preoperative liver function tests, donor hemodynamic stability, and intraoperative normal gross aspect. Octogenarian grafts were deliberately not assigned to retransplantations or to recipients with multiple previous surgical procedures or extensive portal thrombosis. Mean donor age was 82.7 ± 2.1 years, with a range between 80 and 88. Only 12.1% suffered hemodynamic instability during the intensive care unit stay. Three donors (9.1%) had a history of diabetes mellitus. The mean Model for End-Stage Liver Disease score among recipients was 14.7 ± 5.6. Mean cold ischemia time was 302 ± 61 minutes. After a median follow-up of 18.5 months (range 7.5 to 47.5), no graft developed primary nonfunction. We observed hepatic artery thrombosis in 1 patient (3%) and biliary complications in 4 patients (12.5%). There was 1 case of ischemic-type biliary lesion, although it was related to hepatic artery thrombosis. Patient survival at 1 and 3 years was 90.3%, whereas graft survival was 92.6% and 86.4%, respectively. Excellent mid-term results can be obtained after liver transplantation with octogenarian donors with strict donor selection and adequate graft allocation. Copyright © 2016 Elsevier Inc. All rights reserved.

Deceased donor organ transplantation with expanded criteria donors: a single-center experience from India.

PubMed

Goplani, K R; Firoz, A; Ramakrishana, P; Shah, P R; Gumber, M R; Patel, H V; Vanikar, A V; Trivedi, H L

2010-01-01

Deceased donor organ transplantation (DDOT) accounts for <4% of renal transplants in India. Many volunteers come forth for organ donation with increasing awareness; unfortunately, the majority are marginal donors, but their rejection would hamper the DDOT program. Judicious use of marginal organs is a challenge for developing countries. We performed 29 renal transplants from 21 expanded criteria donors (ECD) out of 115 DDOT between January 2006 to April 2009-10 dual (DKT) and 19 single (SKT). Fourteen donors had hypertension, a cerebrovascular accident as the cause of death, 9 had both, and 4 had diabetes. Mean donor age was 70.3 +/- 8.9 years. Decisions on the procedure were based upon frozen section biopsy in 13 of 21 donors. Mean DKT donor age was 76 +/- 9.7 years versu 64 +/- 5.7 years of SKT donors. The native kidney diseases were chronic glomerulonephritis (n = 14), diabetic nephropathy (n = 7), tubulointerstitial nephritis (n = 4) and polycystic kidney disease, focal segmental glomerulosclerosis, lupus nephritis and patchy cortical necrosis, (n = 1 each). Mean recipient age of DKT versus SKT was 43.5 versus 42.3 years. All recipients received rabbit anti-thymocyte globulin, followed by steroid, mycophenolate mofetil/calcinueurin inhibitor. Over a mean follow-up of 341 days, the mean serum creatinine (SCr) of 25/29 patients was 1.60 mg/dL (range, 1.0-2.6). The mean SCr of SKT patients was 1.59 +/- 0.63 mg/dL and of DKT, 1.62 +/- 0.48 mg/dL. Ten patients had delayed graft function and 11 had biopsy proven acute tubular necrosis. Seven (24%) patients had rejection (grade 3 Banff update '05, type IA; 4, type 2A); 6 responded to antirejection; 1 graft was lost at 7 months due to chronic rejection. Three (10.3%) patients were lost, 1 each due to AMI, sepsis, and CMV disease. In the circumstances of organ shortage, DDOT with expanded criteria donor is a feasible option.

Preparation of Pd-Loaded Hierarchical FAU Membranes and Testing in Acetophenone Hydrogenation.

PubMed

Molinari, Raffaele; Lavorato, Cristina; Mastropietro, Teresa F; Argurio, Pietro; Drioli, Enrico; Poerio, Teresa

2016-03-22

Pd-loaded hierarchical FAU (Pd-FAU) membranes, containing an intrinsic secondary non-zeolitic (meso)porosity, were prepared and tested in the catalytic transfer hydrogenation of acetophenone (AP) to produce phenylethanol (PE), an industrially relevant product. The best operating conditions were preliminarily identified by testing different solvents and organic hydrogen donors in a batch hydrogenation process where micron-sized FAU seeds were employed as catalyst support. Water as solvent and formic acid as hydrogen source resulted to be the best choice in terms of conversion for the catalytic hydrogenation of AP, providing the basis for the design of a green and sustainable process. The best experimental conditions were selected and applied to the Pd-loaded FAU membrane finding enhanced catalytic performance such as a five-fold higher productivity than with the unsupported Pd-FAU crystals (11.0 vs. 2.2 mgproduct gcat(-1)·h(-1)). The catalytic performance of the membrane on the alumina support was also tested in a tangential flow system obtaining a productivity higher than that of the batch system (22.0 vs. 11.0 mgproduct gcat(-1)·h(-1)).

Donor-Acceptor-Collector Ternary Crystalline Films for Efficient Solid-State Photon Upconversion.

PubMed

Ogawa, Taku; Hosoyamada, Masanori; Yurash, Brett; Nguyen, Thuc-Quyen; Yanai, Nobuhiro; Kimizuka, Nobuo

2018-06-25

It is pivotal to achieve efficient triplet-triplet annihilation based photon upconversion (TTA-UC) in the solid-state for enhancing potentials of renewable energy production devices. However, the UC efficiency of solid materials is largely limited by low fluorescence quantum yields that originate from the aggregation of TTA-UC chromophores, and also by severe back energy transfer from the acceptor singlet state to the singlet state of the triplet donor in the condensed state. In this work, to overcome these issues, we introduce a highly fluorescent singlet energy collector as the third component of donor-doped acceptor crystalline films, in which dual energy migration, i.e., triplet energy migration for TTA-UC and succeeding singlet energy migration for transferring energy to a collector, takes place. To demonstrate this scheme, a highly fluorescent singlet energy collector was added as the third component of donor-doped acceptor crystalline films. An anthracene-based acceptor containing alkyl chains and a carboxylic moiety is mixed with the triplet donor Pt(II) octaethylporphyrin (PtOEP) and the energy collector 2,5,8,11-tetra- tert-butylperylene (TTBP) in solution, and spin-coating of the mixed solution gives acceptor films of nanofibrous crystals homogeneously doped with PtOEP and TTBP. Interestingly, delocalized singlet excitons in acceptor crystals are found to diffuse effectively over the distance of ~37 nm. Thanks to this high diffusivity, only 0.5 mol% of doped TTBP can harvest most of the singlet excitons, which successfully doubles the solid-state fluorescent quantum yield of acceptor/TTBP blend films to 76%. Furthermore, since the donor PtOEP and the collector TTBP are separately isolated in the nanofibrous acceptor crystals, the singlet back energy transfer from the collector to the donor is effectively avoided. Such efficient singlet energy collection and inhibited back energy transfer processes result in a large increase of UC efficiency up to 9

Trends in pediatric liver transplant donors and deceased donor circumstance of death in the United States, 2002-2015.

PubMed

Yoeli, Dor; Goss, Matthew; Galván, Nhu Thao N; Desai, Moreshwar S; Miloh, Tamir A; Rana, Abbas

2018-05-01

While much of the discussion regarding expanding the donor pool for pediatric liver transplantation has surrounded the use of technical variant grafts, little attention has been directed toward changes in the deceased donor population. The aim of this study was to investigate trends in the circumstance of the death of deceased donors used for pediatric liver transplantation. All pediatric liver transplant recipients transplanted between 2002 and 2015 were identified in the UNOS database and were categorized based on the donor circumstance of death. There was no significant correlation between year of transplantation and number of pediatric liver transplants performed, pediatric donors, split livers, or living donors. There was a significant downward trend in donors from motor vehicle fatalities and an upward trend in suicide, non-MVA, and death due to natural causes. There was also an upward trend in drowning, one of the most common mechanisms of death among non-MVA in 2015. While the number of donors who died in MVA has fallen, the number of deceased donors who died from suicide, natural causes, and non-MVA, especially drowning, has increased, maintaining the overall number of pediatric deceased donor livers transplanted. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Increasing the supply of kidneys for transplantation by making living donors the preferred source of donor kidneys.

PubMed

Testa, Giuliano; Siegler, Mark

2014-12-01

At the present time, increasing the use of living donors offers the best solution to the organ shortage problem. The clinical questions raised when the first living donor kidney transplant was performed, involving donor risk, informed consent, donor protection, and organ quality, have been largely answered. We strongly encourage a wider utilization of living donation and recommend that living donation, rather than deceased donation, become the first choice for kidney transplantation. We believe that it is ethically sound to have living kidney donation as the primary source for organs when the mortality and morbidity risks to the donor are known and kept extremely low, when the donor is properly informed and protected from coercion, and when accepted national and local guidelines for living donation are followed.

Initiating Maintenance Dialysis Before Living Kidney Donor Transplantation When a Donor Candidate Evaluation Is Well Underway.

PubMed

Habbous, Steven; McArthur, Eric; Dixon, Stephanie N; McKenzie, Susan; Garcia-Ochoa, Carlos; Lam, Ngan N; Lentine, Krista L; Dipchand, Christine; Litchfield, Kenneth; Begen, Mehmet A; Sarma, Sisira; Garg, Amit X

2018-07-01

Preemptive kidney transplants result in better outcomes and patient experiences than transplantation after dialysis onset. It is unknown how often a person initiates maintenance dialysis before living kidney donor transplantation when their donor candidate evaluation is well underway. Using healthcare databases, we retrospectively studied 478 living donor kidney transplants from 2004 to 2014 across 5 transplant centers in Ontario, Canada, where the recipients were not receiving dialysis when their donor's evaluation was well underway. We also explored some factors associated with a higher likelihood of dialysis initiation before transplant. A total of 167 (35%) of 478 persons with kidney failure initiated dialysis in a median of 9.7 months (25th-75th percentile, 5.4-18.7 months) after their donor candidate began their evaluation and received dialysis for a median of 8.8 months (3.6-16.9 months) before kidney transplantation. The total cohort's dialysis cost was CAD $8.1 million, and 44 (26%) of 167 recipients initiated their dialysis urgently in hospital. The median total donor evaluation time (time from evaluation start to donation) was 10.6 months (6.4-21.6 months) for preemptive transplants and 22.4 months (13.1-38.7 months) for donors whose recipients started dialysis before transplant. Recipients were more likely to start dialysis if their donor was female, nonwhite, lived in a lower-income neighborhood, and if the transplant center received the recipient referral later. One third of persons initiated dialysis before receiving their living kidney donor transplant, despite their donor's evaluation being well underway. Future studies should consider whether some of these events can be prevented by addressing inappropriate delays to improve patient outcomes and reduce healthcare costs.

A theoretical perspective of the nature of hydrogen-bond types - the atoms in molecules approach

NASA Astrophysics Data System (ADS)

Vijaya Pandiyan, B.; Kolandaivel, P.; Deepa, P.

2014-06-01

Hydrogen bonds and their strength were analysed based on their X-H proton-donor bond properties and the parameters of the H-Y distance (Y proton acceptor). Strong, moderate and weak interactions in hydrogen-bond types were verified through the proton affinities of bases (PA), deprotanation enthalpies of acids (DPE) and the chemical shift (σ). The aromaticity and anti-aromaticity were analysed by means of the NICS (0) (nucleus-independent chemical shift), NICS (1) and ΔNICS (0), ΔNICS (1) of hydrogen-bonded molecules. The strength of a hydrogen bond depends on the capacity of hydrogen atom engrossing into the electronegative acceptor atom. The correlation between the above parameters and their relations were discussed through curve fitting. Bader's theory of atoms in molecules has been applied to estimate the occurrence of hydrogen bonds through eight criteria reported by Popelier et al. The lengths and potential energy shifts have been found to have a strong negative linear correlation, whereas the lengths and Laplacian shifts have a strong positive linear correlation. This study illustrates the common factors responsible for strong, moderate and weak interactions in hydrogen-bond types.

Sulfur Dioxide Enhances Endogenous Hydrogen Sulfide Accumulation and Alleviates Oxidative Stress Induced by Aluminum Stress in Germinating Wheat Seeds

PubMed Central

Zhu, Dong-Bo; Hu, Kang-Di; Guo, Xi-Kai; Liu, Yong; Hu, Lan-Ying; Li, Yan-Hong; Wang, Song-Hua; Zhang, Hua

2015-01-01

Aluminum ions are especially toxic to plants in acidic soils. Here we present evidences that SO2 protects germinating wheat grains against aluminum stress. SO2 donor (NaHSO3/Na2SO3) pretreatment at 1.2 mM reduced the accumulation of superoxide anion, hydrogen peroxide, and malondialdehyde, enhanced the activities of guaiacol peroxidase, catalase, and ascorbate peroxidase, and decreased the activity of lipoxygenase in germinating wheat grains exposed to Al stress. We also observed higher accumulation of hydrogen sulfide (H2S) in SO2-pretreated grain, suggesting the tight relation between sulfite and sulfide. Wheat grains geminated in water for 36 h were pretreated with or without 1 mM SO2 donor for 12 h prior to exposure to Al stress for 48 h and the ameliorating effects of SO2 on wheat radicles were studied. SO2 donor pretreatment reduced the content of reactive oxygen species, protected membrane integrity, and reduced Al accumulation in wheat radicles. Gene expression analysis showed that SO2 donor pretreatment decreased the expression of Al-responsive genes TaWali1, TaWali2, TaWali3, TaWali5, TaWali6, and TaALMT1 in radicles exposed to Al stress. These results suggested that SO2 could increase endogenous H2S accumulation and the antioxidant capability and decrease endogenous Al content in wheat grains to alleviate Al stress. PMID:26078810

Evaluation of biodegradable plastics as solid hydrogen donors for the reductive dechlorination of fthalide by Dehalobacter species.

PubMed

Yoshida, Naoko; Ye, Lizhen; Liu, Fengmao; Li, Zhiling; Katayama, Arata

2013-02-01

Biodegradable plastics (BPs) were evaluated for their applicability as sustainable and solid H(2) donors for microbial reductive dechlorination of 4,5,6,7-tetrachlorophthalide (fthalide). After a screening test of several BPs, the starch-based plastic (SP) that produced the highest levels of H(2) was selected for its use as the sole H(2) donor in this reaction. Fthalide dechlorination was successfully accomplished by combining an H(2)-producing SP culture and a KFL culture containing Dehalobacter species, supplemented with 0.13% and 0.5% SP, respectively. The efficiency of H(2) use in dechlorination was evaluated in a combined culture containing the KFL culture and strain Clostridium sp. Ma13, a new isolate that produces H(2) from SP. Results obtained with this culture indicated increased H(2)-fraction for fthalide dechlorination much more in this culture than in compared with a KFL culture supplemented with 20mM lactate, which are 0.75 H(2)·glucose(-1) and 0.015 H(2)·lactate(-1) in mol ratio, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Return behavior of occasional and multigallon blood donors: the role of theory of planned behavior, self-identity, and organizational variables.

PubMed

Wevers, Anne; Wigboldus, Daniël H J; van Baaren, Rick; Veldhuizen, Ingrid J T

2014-03-01

For blood establishments it is important that blood donors return for a donation. Past research has stressed the importance of theory of planned behavior (TPB) on return behavior, but self-identity (SI) and organizational variables (OVs) might play a role as well. This study added SI and OVs to the TPB to identify the determinants for return behavior. Whole blood donors (n = 2005) completed a questionnaire assessing TPB, SI, and OVs. OVs contained "perceived satisfaction with the blood bank" and "feeling pressure from the blood bank to donate blood." Return behavior over the past 2 years was dichotomized as low return (0%-50%) versus high return (51%-100%). Logistic regression analyses assessed the effects of TPB, SI, and OVs on high return, separately for occasional donors (two to 10 lifetime donations) and multigallon donors (>10 lifetime donations). Results showed that, for all donors, affective attitude was positively associated with return behavior, whereas pressure to donate blood was negatively associated with return behavior. The point estimates of self-efficacy, SI, and perceived satisfaction are high for multigallon donors, but do not reach significance. For all donors, positive feelings about donating blood stimulate return behavior, while experiencing a pressure to donate blood emanating from the blood bank was not beneficial. Results suggest that multigallon donors are more stimulated to return when they score higher on self-efficacy, SI, and perceived satisfaction. Interventions aiming at donor retention need to be carefully formulated to avoid negative effects of feeling pressure to donate blood. © 2013 American Association of Blood Banks.

Donor Telomere Length SAA

Cancer.gov

A new NCI study has found that, among patients with severe aplastic anemia who received a hematopoietic cell transplant from an unrelated donor, those whose donor white blood cells had longer telomeres had higher survival rates five-years after transplant

Hydrogen peroxide stabilization in one-dimensional flow columns.

PubMed

Schmidt, Jeremy T; Ahmad, Mushtaque; Teel, Amy L; Watts, Richard J

2011-09-25

Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H(2)O(2) propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO. Copyright © 2011. Published by Elsevier B.V.

Emissions and Total Energy Consumption of a Multicylinder Piston Engine Running on Gasoline and a Hydrogen-gasoline Mixture

NASA Technical Reports Server (NTRS)

Cassidy, J. F.

1977-01-01

A multicylinder reciprocating engine was used to extend the efficient lean operating range of gasoline by adding hydrogen. Both bottled hydrogen and hydrogen produced by a research methanol steam reformer were used. These results were compared with results for all gasoline. A high-compression-ratio, displacement production engine was used. Apparent flame speed was used to describe the differences in emissions and performance. Therefore, engine emissions and performance, including apparent flame speed and energy lost to the cooling system and the exhaust gas, were measured over a range of equivalence ratios for each fuel. All emission levels decreased at the leaner conditions. Adding hydrogen significantly increased flame speed over all equivalence ratios.

Open-Identity Sperm Donation: How Does Offering Donor-Identifying Information Relate to Donor-Conceived Offspring's Wishes and Needs?

PubMed

Ravelingien, An; Provoost, Veerle; Pennings, Guido

2015-09-01

Over the past years, a growing number of countries have legislated open-identity donation, in which donor-conceived offspring are given access to the donor's identity once the child has reached maturity. It is held that donor anonymity creates identity problems for such children similar to the "genealogical bewilderment" described within the adoption context. The study of the social and psychological effects of open-identity donation is still very much in its infancy, but what has been left unquestioned is whether (and to what extent) offering access to the donor's name and address is an adequate response to such effects. This study has two goals: First, we aim to provide a systematic review of the reasons why donor-conceived (DC) offspring want to know the identity of their sperm donor. Second, we examine to what extent the provision of donor-identifying information can satisfy the reasons mentioned. The most important motivations appear to be: (1) to avoid medical risks and consanguineous relationships; (2) to satisfy curiosity; (3) to learn more about the self or to complete one's identity; (4) to learn more about what kind of person the donor is (biographical information, why he donated, etc.); (5) to form a relationship with the donor and/or his family; and (6) to learn about one's ancestry/genealogy. Our analysis shows that for nearly all of these reasons access to the donor's identity is not necessary. In those cases where it is, moreover, donor identification is not sufficient. What is really needed is (extended) contact with the donor, rather than the mere provision of his name.

Increasing the Rate of Living Donor Kidney Transplantation in Ontario: Donor- and Recipient-Identified Barriers and Solutions

PubMed Central

Getchell, Leah E.; McKenzie, Susan Q.; Sontrop, Jessica M.; Hayward, Jade S.; McCallum, Megan K.; Garg, Amit X.

2017-01-01

Purpose of Review: To hear from living kidney donors and recipients about what they perceive are the barriers to living donor kidney transplantation, and how patients can develop and lead innovative solutions to increase the rate and enhance the experiences of living donor kidney transplantation in Ontario. Sources of Information: A one-day patient-led workshop on March 10th, 2016 in Toronto, Ontario. Methods: Participants who were previously engaged in priority-setting exercises were invited to the meeting by patient lead, Sue McKenzie. This included primarily past kidney donors, kidney transplant recipients, as well as researchers, and representatives from renal and transplant health care organizations across Ontario. Key Findings: Four main barriers were identified: lack of education for patients and families, lack of public awareness about living donor kidney transplantation, financial costs incurred by donors, and health care system-level inefficiencies. Several novel solutions were proposed, including the development of a peer network to support and educate patients and families with kidney failure to pursue living donor kidney transplantation; consistent reimbursement policies to cover donors’ out-of-pocket expenses; and partnering with the paramedical and insurance industry to improve the efficiency of the donor and recipient evaluation process. Limitations: While there was a diversity of experience in the room from both donors and recipients, it does not provide a complete picture of the living kidney donation process for all Ontario donors and recipients. The discussion was provincially focused, and as such, some of the solutions suggested may already be in practice or unfeasible in other provinces. Implications: The creation of a patient-led provincial council was suggested as an important next step to advance the development and implementation of solutions to overcome patient-identified barriers to living donor kidney transplantation. PMID:28491334

Donor recruitment and selection for adult-to-adult living donor liver transplantation in urgent and elective circumstances.

PubMed

Ben-Haim, Menahem; Carmiel, Michal; Lubezky, Nir; Keidar, Rivka; Katz, Paulina; Blachar, Arye; Nimrod, Adi; Sorkine, Patrick; Oren, Ran; Klausner, Joseph M; Nakache, Richard

2005-03-01

Adult-to-adult living donor liver transplantation is becoming an alternative to cadaveric transplantation in urgent and elective settings. Donor selection crucially affects donor safety and recipient outcome. To present our algorithm of urgent and elective donor selection. Urgent selection is expeditious and protocol-based. Elective selection permits a comprehensive process. Both include medical, psychosocial and surgical-anatomic evaluations. Liver volumes and vascular anatomy are evaluated with computerized tomographic angiography. Informed consent is obtained after painstaking explanations. Independent institutional committees review and approve all cases. Between July 2003 and June 2004 we evaluated 43 potential live donors for 12 potential recipients (fulminant hepatic failure, n = 5; chronic end-stage liver disease, n = 6; primary graft non-function, n = 1). Thirty-three candidates (76%) were excluded due to blood type incompatibility (n = 14, 42%), incompatible anatomy (n = 8, 24%)--including problematic volume distribution (n = 2) or vascular anatomy (n = 6)--psychosocial issues (n = 4, 12%), or medical co-morbidity (n = 7, 22%). Five recipients (FHF, n = 4; chronic ESLD, n = 1) were successfully transplanted from living donors. In the acute setting, two patients (FHF, PGNF) died in the absence of an appropriate donor (cadaveric or living donor). In the elective group, one patient died of unexpected variceal bleeding and one received a cadaveric graft just before the planned living donor transplantation was performed. One candidate was transplanted overseas and two cases are scheduled. The ratio of compatibility for donation was 34% (10/29) for blood type-compatible candidates. Donor selection for living donor liver transplantation is a complex, labor-intensive multidisciplinary process. Most exclusions are due to blood type incompatibility or anatomic details. Psychosocial aspects of these donations warrant special attention.

The hydrogen peroxide impact on larval settlement and metamorphosis of abalone Haliotis diversicolor supertexta

NASA Astrophysics Data System (ADS)

Zhang, Xiangjing; Yang, Zhihui; Cai, Zhonghua

2008-08-01

Abalone Haliotis diversicolor supertexta is an important economic mollusk. The settlement and metamorphosis are two critical stages during its development period, which has direct influence on abalone survival and production. The influence of reactive oxygen species (hydrogen peroxide) on abalone embryo and juvenile development were examined in this study. Larvae of Haliotis diversicolor supertexta were induced to settlement and metamorphose by exposure to seawater supplemented with hydrogen peroxide. They had the best performance at 800 μmol/L. The concentration of 1 000 μmol/L or higher was toxic to the larvae, as the larvae could settle down only at benthic diatom plates without complete metamorphosis. In addition, H2O2 adding time was critical to the larval performance. 24h after two-day post-fertilization was proved to be the optimal adding time. In this paper, two action mechanisms of hydrogen peroxide are discussed: (1) hydrogen peroxide has direct toxicity to ciliated cells, thus cause apoptosis; (2) hydrogen peroxide, as a product from catecholamines’ autoxidation process in vivo, can reverse this process to produce neuro-transmitters to induce abalone metamorphosis.

Diverse Cd(II) compounds based on N-benzoyl-L-glutamic acid and N-donor ligands: Structures and photoluminescent properties

NASA Astrophysics Data System (ADS)

Ma, Ning; Guo, Wei-Ying; Song, Hui-Hua; Yu, Hai-Tao

2016-01-01

Five new Cd(II) coordination polymers with N-benzoyl-L-glutamic acid (H2bzgluO) and different N-donor ligands, [Cd(bzgluO)(2,2‧-bipy)(H2O)]n (1), [Cd(bzgluO)(2,4‧-bipy)2(H2O)·3H2O]n (2), [Cd(bzgluO)(phen)·H2O]n (3), [Cd(bzgluO)(4,4‧-bipy)(H2O)]n (4), [Cd(bzgluO)(bpp)(H2O)·2H2O]n (5) were synthesized (2,2‧-bipy=2,2‧-bipyridine, 2,4‧-bipy=2,4‧-bipyridine, phen=1,10-phenanthroline, 4,4‧-bipy=4,4‧-bipyridine, bpp=1,3-di(4-pyridyl)propane). Compounds 1-2 exhibit a 1D single-chain structure. Compound 1 generates a 2D supramolecular structure via π-π stacking and hydrogen bonding, 3D architecture of compound 2 is formed by hydrogen bonding. Compound 3 features a 1D double-chain structure, which are linked by π-π interactions into a 2D supramolecular layer. Compounds 4-5 display a 2D network structure. Neighboring layers of 4 are extended into a 3D supramolecular architecture through hydrogen bonding. The structural diversity of these compounds is attributed to the effect of ancillary N-donor ligands and coordination modes of H2bzgluO. Luminescent properties of 1-5 were studied at room temperature. Circular dichroism of compounds 1, 2 and 5 were investigated.

[Lack of donor organs as an argument for living donors?].

PubMed

Kirste, G

2010-09-01

In Germany more than 12,000 patients are presently waiting for an organ donation. Living donation makes sense for the long waiting time for a kidney, but it is not a permanent solution for the lack of organ donations. In the future topics which should be discussed are intensified public relations, a better family care and the allocation of rights and duties at the German coordinating agency. For all the prospects of success after a living donation the high standards of quality and security, which are targeted by the German donor organization in recipient protection, responsible evaluation of the expanded donor criteria and immunosuppressive therapy are all in favor of post-mortem organ donation. For all the phenomenal chance of success the priority of the post-mortem organ donation is regulated by law. The living donation remains an individual decision of the donor and the personal situation of life.

Outcomes of management for potential deceased donors.