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.

Fullerene derivatives as electron donor for organic photovoltaic cells

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

Zhuang, Taojun; Wang, Xiao-Feng, E-mail: xf-wang@yz.yamagata-u.ac.jp, E-mail: ziruo@yz.yamagata-u.ac.jp; Sano, Takeshi

2013-11-11

We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C{sub 60} bisadduct (ICBA) and phenyl C{sub 61}-butyric acid methyl ester as the electron donors with fullerene C{sub 70} as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5 nm ICBA/40 nm C{sub 70} PHJ cell gives clear external quantummore » efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.« less

The tyranny of the gift: sacrificial violence in living donor transplants.

PubMed

Scheper-Hughes, N

2007-03-01

Medical anthropology can bring to living donor transplant useful insights on the nature of gifting, family obligations, reciprocity and invisible sacrifice. Whereas, ethical reflections and debates on the marketing of tissues and organs, especially sales by living strangers, have proliferated to the point of saturation, the larger issue of the ethics of "altruistic" donation by and among family members is more rarely the focus of bio-ethical scrutiny and discussion today, though of course it was much debated in the early decades of kidney transplant. As the proportion of living over deceased donors (especially of kidneys) has increased markedly in the past decade, the time is ripe to revisit the topic, which I shall do via three vignettes, all of them informed by my 10 years as founding Director of Organs Watch, an independent, university-based, anthropological and ethnographic field-research and medical human rights project. Whereas living-related (altruistic) and living-unrelated (commercial) donation are often treated as very different phenomena, I will illustrate what social elements are shared. In both instances, paid kidney sellers and related donors, are often responding to family pressures and to a call to "sacrifice".

Sacrificial plastic mold with electroplatable base

DOEpatents

Domeier, Linda A.; Hruby, Jill M.; Morales, Alfredo M.

2002-01-01

A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

Sacrificial Plastic Mold With Electroplatable Base

DOEpatents

Domeier, Linda A.; Hruby, Jill M.; Morales, Alfredo M.

2005-08-16

A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

Sacrificial charge and the spectral resolution performance of the Chandra advanced CCD imaging spectrometer

NASA Astrophysics Data System (ADS)

Grant, Catherine E.; Prigozhin, Gregory Y.; LaMarr, Beverly; Bautz, Mark W.

2003-03-01

Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the focal plane instruments on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. The ACIS team is continuing to study the properties of the damage with an emphasis on developing techniques to mitigate charge transfer inefficiency (CTI) and spectral resolution degradation. A post-facto CTI corrector has been developed which can effectively recover much of the lost resolution. Any further improvements in performance will require knowledge of the location and amount of sacrificial charge - charge deposited along the readout path of an event which fills electron traps and changes CTI. We report on efforts by the ACIS Instrument team to characterize which charge traps cause performance degradation and the properties of the sacrificial charge seen on-orbit. We also report on attempts to correct X-ray pulseheights for the presence of sacrificial charge.

Electron shuttling in phosphorus donor qubit systems

NASA Astrophysics Data System (ADS)

Jacobson, N. Tobias; Gamble, John King; Nielsen, Erik; Muller, Richard P.; Witzel, Wayne M.; Montano, Ines; Carroll, Malcolm S.

2014-03-01

Phosphorus donors in silicon are a promising qubit architecture, due in large part to their long nuclear coherence times and the recent development of atomically precise fabrication methods. Here, we investigate issues related to implementing qubits with phosphorus donors in silicon, employing an effective mass theory that non-phenomenologically takes into account inter-valley coupling. We estimate the significant sources of decoherence and control errors in this system to compute the fidelity of primitive gates and gate timescales. We include the effects of valley repopulation during the process of shuttling an electron between a donor and nearby interface or between neighboring donors, evaluating the control requirements for ensuring adiabaticity with respect to the valley sector. This work was supported in part by the LDRD program at Sandia National Labs, a multi-program laboratory managed and operated by Sandia Corp, a wholly owned subsidiary of Lockheed Martin Corp, for the U.S. DOE NNSA under contract DE-AC04-94AL85000.

Ultrafast photoinduced charge transport in Pt(II) donor-acceptor assembly bearing naphthalimide electron acceptor and phenothiazine electron donor.

PubMed

Sazanovich, Igor V; Best, Jonathan; Scattergood, Paul A; Towrie, Michael; Tikhomirov, Sergei A; Bouganov, Oleg V; Meijer, Anthony J H M; Weinstein, Julia A

2014-12-21

Visible light-induced charge transfer dynamics were investigated in a novel transition metal triad acceptor-chromophore-donor, (NDI-phen)Pt(II)(-C≡C-Ph-CH2-PTZ)2 (1), designed for photoinduced charge separation using a combination of time-resolved infrared (TRIR) and femtosecond electronic transient absorption (TA) spectroscopy. In 1, the electron acceptor is 1,4,5,8-naphthalene diimide (NDI), and the electron donor is phenothiazine (PTZ), and [(phen)Pt(-C≡C-Ph-)], where phen is 1,10-phenanthroline, represents the chromophoric core. The first excited state observed in 1 is a (3)MLCT/LL'CT, with {Pt(II)-acetylide}-to-phen character. Following that, charge transfer from the phen-anion onto the NDI subunit to form NDI(-)-phen-[Pt-(C≡C)2](+)-PTZ2 occurs with a time constant of 2.3 ps. This transition is characterised by appearance of the prominent NDI-anion features in both TRIR and TA spectra. The final step of the charge separation in 1 proceeds with a time constant of ∼15 ps during which the hole migrates from the [Pt-(C≡C)2] subunit to one of the PTZ groups. Charge recombination in 1 then occurs with two distinct time constants of 36 ns and 107 ns, corresponding to the back electron transfer to each of the two donor groups; a rather rare occurrence which manifests that the hole in the final charge-separated state is localised on one of the two donor PTZ groups. The assignment of the nature of the excited states and dynamics in 1 was assisted by TRIR investigations of the analogous previously reported ((COOEt)2bpy)Pt(C≡C-Ph-CH2-PTZ)2 (2), (J. E. McGarrah and R. Eisenberg, Inorg. Chem., 2003, 42, 4355; J. E. McGarrah, J. T. Hupp and S. N. Smirnov, J. Phys. Chem. A, 2009, 113, 6430) as well as (bpy)Pt(C≡C-Ph-C7H15)2, which represent the acceptor-free dyad, and the chromophoric core, respectively. Thus, the step-wise formation of the full charge-separated state on the picosecond time scale and charge recombination via tunnelling have been established; and

Effect of two intermediate electron donors, NADPH and FADH(2), on Spirulina Delta (6)-desaturase co-expressed with two different immediate electron donors, cytochrome b (5) and ferredoxin, in Escherichia coli.

PubMed

Kurdrid, Pavinee; Subudhi, Sanjukta; Cheevadhanarak, Supapon; Tanticharoen, Morakot; Hongsthong, Apiradee

2007-12-01

When the gene desD encoding Spirulina Delta(6)-desaturase was heterologously expressed in E. coli, the enzyme was expressed without the ability to function. However, when this enzyme was co-expressed with an immediate electron donor, i.e. the cytochrome b (5) domain from Mucor rouxii, the results showed the production of GLA (gamma-linolenic acid), the product of the reaction catalyzed by Delta(6)-desaturase. The results revealed that in E. coli cells, where cytochrome b (5) is absent and ferredoxin, a natural electron donor of Delta(6)-desaturase, is present at a very low level, the cytochrome b (5) domain can complement for the function of ferredoxin in the host cells. In the present study, the Spirulina-ferredoxin gene was cloned and co-expressed with the Delta(6)-desaturase in E. coli. In comparison to the co-expression of cytochrome b ( 5 ) with the Delta(6)-desaturase, the co-expression with ferredoxin did not cause any differences in the GLA level. Moreover, the cultures containing the Delta(6)-desaturase co-expressed with cytochrome b (5) and ferredoxin were exogenously supplied with the intermediate electron donors, NADPH (nicotinamide adenine dinucleotide phosphate, reduced form) and FADH(2) (flavin adenine dinucleotide, reduced form), respectively. The GLA level in these host cells increased drastically, by approximately 50%, compared to the cells without the intermediate electron donors. The data indicated that besides the level of immediate electron donors, the level of intermediate electron donors is also critical for GLA production. Therefore, if the pools of the immediate and intermediate electron donors in the cells are manipulated, the GLA production in the heterologous host will be affected.

Spin-orbit coupling induced two-electron relaxation in silicon donor pairs

NASA Astrophysics Data System (ADS)

Song, Yang; Das Sarma, S.

2017-09-01

We unravel theoretically a key intrinsic relaxation mechanism among the low-lying singlet and triplet donor-pair states in silicon, an important element in the fast-developing field of spintronics and quantum computation. Despite the perceived weak spin-orbit coupling (SOC) in Si, we find that our discovered relaxation mechanism, combined with the electron-phonon and interdonor interactions, drives the transitions in the two-electron states over a large range of donor coupling regimes. The scaling of the relaxation rate with interdonor exchange interaction J goes from J5 to J4 at the low to high temperature limits. Our analytical study draws on the symmetry analysis over combined band, donor envelope, and valley configurations. It uncovers naturally the dependence on the donor-alignment direction and triplet spin orientation, and especially on the dominant SOC source from donor impurities. While a magnetic field is not necessary for this relaxation, unlike in the single-donor spin relaxation, we discuss the crossover behavior with increasing Zeeman energy in order to facilitate comparison with experiments.

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.

Reducing graphene device variability with yttrium sacrificial layers

NASA Astrophysics Data System (ADS)

Wang, Ning C.; Carrion, Enrique A.; Tung, Maryann C.; Pop, Eric

2017-05-01

Graphene technology has made great strides since the material was isolated more than a decade ago. However, despite improvements in growth quality and numerous "hero" devices, challenges of uniformity remain, restricting the large-scale development of graphene-based technologies. Here, we investigate and reduce the variability of graphene transistors by studying the effects of contact metals (with and without a Ti layer), resist, and yttrium (Y) sacrificial layers during the fabrication of hundreds of devices. We find that with optical photolithography, residual resist and process contamination are unavoidable, ultimately limiting the device performance and yield. However, using Y sacrificial layers to isolate the graphene from processing conditions improves the yield (from 73% to 97%), the average device performance (three-fold increase of mobility and 58% lower contact resistance), and the device-to-device variability (standard deviation of Dirac voltage reduced by 20%). In contrast to other sacrificial layer techniques, the removal of the Y sacrificial layer with dilute HCl does not harm surrounding materials, simplifying large-scale graphene fabrication.

Phylogenetic analysis of TCE-dechlorinating consortia enriched on a variety of electron donors.

PubMed

Freeborn, Ryan A; West, Kimberlee A; Bhupathiraju, Vishvesh K; Chauhan, Sadhana; Rahm, Brian G; Richardson, Ruth E; Alvarez-Cohen, Lisa

2005-11-01

Two rapidly fermented electron donors, lactate and methanol, and two slowly fermented electron donors, propionate and butyrate, were selected for enrichment studies to evaluate the characteristics of anaerobic microbial consortia that reductively dechlorinate TCE to ethene. Each electron donor enrichment subculture demonstrated the ability to dechlorinate TCE to ethene through several serial transfers. Microbial community analyses based upon 16S rDNA, including terminal restriction fragment length polymorphism (T-RFLP) and clone library/sequencing, were performed to assess major changes in microbial community structure associated with electron donors capable of stimulating reductive dechlorination. Results demonstrated that five phylogenic subgroups or genera of bacteria were present in all consortia, including Dehalococcoides sp., low G+C Gram-positives (mostly Clostridium and Eubacterium sp.), Bacteroides sp., Citrobacter sp., and delta Proteobacteria (mostly Desulfovibrio sp.). Phylogenetic association indicates that only minor shifts in the microbial community structure occurred between the four alternate electron donor enrichments and the parent consortium. Inconsistent detection of Dehalococcoides spp. in clone libraries and T-RFLP of enrichment subcultures was resolved using quantitative polymerase chain reaction (Q-PCR). Q-PCR with primers specific to Dehalococcoides 16S rDNA resulted in positive detection of this species in all enrichments. Our results suggest that TCE-dechlorinating consortia can be stably maintained on a variety of electron donors and that quantities of Dehalococcoides cells detected with Dehalococcoides specific 16S rDNA primer/probe sets do not necessarily correlate well with solvent degradation rates.

Electronic messaging and communication with living kidney donors.

PubMed

Ruck, Jessica M; Zhou, Sheng; Thomas, Alvin G; Cramm, Shannon L; Massie, Allan B; Montgomery, John R; Berger, Jonathan C; Henderson, Macey L; Segev, Dorry L

2018-02-01

New regulations require living kidney donor (LKD) follow-up for 2 years, but donor retention remains poor. Electronic communication (eg, text messaging and e-mail) might improve donor retention. To explore the possible impact of electronic communication, we recruited LKDs to participate in an exploratory study of communication via telephone, e-mail, or text messaging postdonation; communication through this study was purely optional and did not replace standard follow-up. Of 69 LKDs recruited, 3% requested telephone call, 52% e-mail, and 45% text messaging. Telephone response rate was 0%; these LKDs were subsequently excluded from analysis. Overall response rates with e-mail or text messaging at 1 week, 1 month, 6 months, 1 year, and 2 years were 94%, 87%, 81%, 72%, and 72%. Lower response rates were seen in African Americans, even after adjusting for age, sex, and contact method (incidence rate ratio (IRR) nonresponse 2.07 5.81 16.36 , P = .001). Text messaging had higher response rates than e-mail (IRR nonresponse 0.11 0.28 0.71 , P = .007). Rates of nonresponse were similar by sex (IRR 0.68, P = .4) and age (IRR 1.00, P > .9). In summary, LKDs strongly preferred electronic messaging over telephone and were highly responsive 2 years postdonation, even in this nonrequired, nonincentivized exploratory research study. These electronic communication tools can be automated and may improve regulatory compliance and postdonation care. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Interplay between barrier width and height in electron tunneling: photoinduced electron transfer in porphyrin-based donor-bridge-acceptor systems.

PubMed

Pettersson, Karin; Wiberg, Joanna; Ljungdahl, Thomas; Mårtensson, Jerker; Albinsson, Bo

2006-01-12

The rate of electron tunneling in molecular donor-bridge-acceptor (D-B-A) systems is determined both by the tunneling barrier width and height, that is, both by the distance between the donor and acceptor as well as by the energy gap between the donor and bridge moieties. These factors are therefore important to control when designing functional electron transfer systems, such as constructs for photovoltaics, artificial photosynthesis, and molecular scale electronics. In this paper we have investigated a set of D-B-A systems in which the distance and the energy difference between the donor and bridge states (DeltaEDB) are systematically varied. Zinc(II) and gold(III) porphyrins were chosen as electron donor and acceptor because of their suitable driving force for photoinduced electron transfer (-0.9 eV in butyronitrile) and well-characterized photophysics. We have previously shown, in accordance with the superexchange mechanism for electron transfer, that the electron transfer rate is proportional to the inverse of DeltaEDB in a series of zinc/gold porphyrin D-B-A systems with bridges of constant edge to edge distance (19.6 A) and varying DeltaEDB (3900-17 600 cm(-1)). Here, we use the same donor and acceptor but the bridge is shortened or extended giving a set of oligo-p-phenyleneethynylene bridges (OPE) with four different edge to edge distances ranging from 12.7 to 33.4 A. These two sets of D-B-A systems-ZnP-RB-AuP+ and ZnP-nB-AuP+-have one bridge in common, and hence, for the first time both the distance and DeltaEDB dependence of electron transfer can be studied simultaneously in a systematic way.

Electron-Transfer Dynamics for a Donor-Bridge-Acceptor Complex in Ionic Liquids.

PubMed

DeVine, Jessalyn A; Labib, Marena; Harries, Megan E; Rached, Rouba Abdel Malak; Issa, Joseph; Wishart, James F; Castner, Edward W

2015-08-27

Intramolecular photoinduced electron transfer from an N,N-dimethyl-p-phenylenediamine donor bridged by a diproline spacer to a coumarin 343 acceptor was studied using time-resolved fluorescence measurements in three ionic liquids and in acetonitrile. The three ionic liquids have the bis[(trifluoromethyl)sulfonyl]amide anion paired with the tributylmethylammonium, 1-butyl-1-methylpyrrolidinium, and 1-decyl-1-methylpyrrolidinium cations. The dynamics in the two-proline donor-bridge-acceptor complex are compared to those observed for the same donor and acceptor connected by a single proline bridge, studied previously by Lee et al. (J. Phys. Chem. C 2012, 116, 5197). The increased conformational freedom afforded by the second bridging proline resulted in multiple energetically accessible conformations. The multiple conformations have significant variations in donor-acceptor electronic coupling, leading to dynamics that include both adiabatic and nonadiabatic contributions. In common with the single-proline bridged complex, the intramolecular electron transfer in the two-proline system was found to be in the Marcus inverted regime.

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

Spin Measurements of an Electron Bound to a Single Phosphorous Donor in Silicon

NASA Astrophysics Data System (ADS)

Luhman, D. R.; Nguyen, K.; Tracy, L. A.; Carr, S. M.; Borchardt, J.; Bishop, N. C.; Ten Eyck, G. A.; Pluym, T.; Wendt, J.; Carroll, M. S.; Lilly, M. P.

2014-03-01

The spin of an electron bound to a single donor implanted in silicon is potentially useful for quantum information processing. We report on our efforts to measure and manipulate the spin of an electron bound to a single P donor in silicon. A low number of P donors are implanted using a self-aligned process into a silicon substrate in close proximity to a single-electron-transistor (SET) defined by lithographically patterned polysilicon gates. The SET is used to sense the occupancy of the electron on the donor and for spin read-out. An adjacent transmission line allows the application of microwave pulses to rotate the spin of the electron. We will present data from various experiments designed to exploit these capabilities. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. The work was supported by Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

Comparison of nitrogen removal and microbial distribution in wastewater treatment process under different electron donor conditions.

PubMed

Park, Sora; Seon, Jiyun; Byun, Imgyu; Cho, Sunja; Park, Taejoo; Lee, Taeho

2010-05-01

The applicability of modified spent caustic (MSC) as an electron donor for denitrification was evaluated in a lab-scale reactor for the Bardenpho process under various electron donor conditions: (A) no electron donor, (B) methanol, (C) thiosulfate and (D) MSC conditions. TN removal efficiency varied in each condition, 23.1%, 87.8%, 83.7% and 71.7%, respectively. The distribution ratio of nitrifying bacteria and DGGE profile including sulfur-reducing or oxidizing bacteria also varied depending on the conditions. These results indicated that the MSC would be used as an efficient electron donor for denitrification by autotrophic denitrifier in wastewater treatment process. Copyright 2009 Elsevier Ltd. All rights reserved.

Photosensitized H2 Production Using a Zinc Porphyrin-Substituted Protein, Platinum Nanoparticles, and Ascorbate with No Electron Relay: Participation of Good's Buffers.

PubMed

Clark, Emily R; Kurtz, Donald M

2017-04-17

Development of efficient light-driven splitting of water, 2H 2 O → 2H 2 + O 2 , often attempts to optimize photosensitization of the reductive and oxidative half-reactions individually. Numerous homogeneous and heterogeneous systems have been developed for photochemical stimulation of the reductive half reaction, 2H + + 2e - → H 2 . These systems generally consist of various combinations of a H + reduction catalyst, a photosensitizer (PS), and a "sacrificial" electron donor. Zinc(II)-porphyrins (ZnPs) have frequently been used as PSs for H 2 generation, but they are subject to various self-quenching processes in aqueous solutions. Colloidal platinum in nanoparticle form (Pt NP) is a classical H + reduction catalyst using ZnP photosensitizers, but efficient photosensitized H 2 generation requires an electron relay molecule between ZnP and Pt NP. The present report describes an aqueous system for visible (white) light-sensitized generation of H 2 using a protein-embedded Zn(II)-protoporphyrin IX as PS and Pt NP as H + reduction catalyst without an added electron relay. This system operated efficiently in piperazino- and morpholino-alkylsulfonic acid (Good's buffers), which served as sacrificial electron donors. The system also required ascorbate at relatively modest concentrations, which stabilized the Zn(II)-protoporphyrin IX against photodegradation. In the absence of an electron relay molecule, the photosensitized H 2 generation must involve formation of at least a transient complex between a protein-embedded Zn(II)-protoporphyrin IX species and Pt NP.

Lift-off process for fine-patterned PZT film using metal oxide as a sacrificial layer

NASA Astrophysics Data System (ADS)

Trong Tue, Phan; Shimoda, Tatsuya; Takamura, Yuzuru

2017-01-01

Patterning of lead zirconium titanate (PZT) films is crucial for highly integrated piezoelectric/ferroelectric micro-devices. In this work, we report a novel lift-off method using solution-processed indium zinc oxide (IZO) thin film as a sacrificial layer for sub-5 µm fine-patterning PZT film. The processes include IZO layer deposition and patterning, PZT film preparation, and final lift-off. The results reveal that the lift-off PZT processes provide better structural and electrical properties than those formed by the conventional wet-etching method. The successful patterning by the lift-off was mainly due to the fact that the IZO sacrificial layer is easy to etch and has a high-temperature resistance. This finding shows great promise for highly integrated electronic devices.

Study of intermediates from transition metal excited-state electron-transfer reactions

NASA Astrophysics Data System (ADS)

Hoffman, M. Z.

1984-03-01

Attention during the past year focused on MV(+)., the reduced methyl viologen radical cation, which is a precursor to the formation of H2 in the photosensitized reduction of water. Through the use of photochemical and radiation chemical techniques, the efficiency of interaction of MV(+). with colloidal Pt, the stability of MV(+). as a function of pH, the quantum yield of formation of MV(+). in the Ru(bpy)3(2+)/MV(2+)/EDTA system, and the formation of photoactive charge-transfer complexes between MV(2+) and sacrificial electron donors were studied.

46 CFR 35.01-25 - Sacrificial anode installations-TB/ALL.

Code of Federal Regulations, 2013 CFR

2013-10-01

... installation of magnesium sacrificial anodes in cargo tanks utilized for the carriage of flammable or... analysis of the alloy composition shall be submitted for approval. The anode should be magnesium free and... consideration. (c) Sacrificial anodes using materials other than those having aluminum and/or magnesium in whole...

46 CFR 35.01-25 - Sacrificial anode installations-TB/ALL.

Code of Federal Regulations, 2014 CFR

2014-10-01

... installation of magnesium sacrificial anodes in cargo tanks utilized for the carriage of flammable or... analysis of the alloy composition shall be submitted for approval. The anode should be magnesium free and... consideration. (c) Sacrificial anodes using materials other than those having aluminum and/or magnesium in whole...

A novel signal-on photoelectrochemical immunosensor for detection of alpha-fetoprotein by in situ releasing electron donor.

PubMed

Chen, Jiexia; Zhao, Guang-Chao

2017-12-15

A signal-on photoelectrochemical (PEC) immunosensor was constructed for detecting tumor marker in this work. α-fetoprotein (AFP) was chosen as a model analyte to investigate the prepared procedure and the analytical performance of the exploited sensor. In order to construct the sensor, CdSe QDs were used as photoactive material, biotin conjugated AFP antibody (Bio-anti-AFP) as detecting probe, streptavidin (SA) as signal capturing unit, biotin functionalized apoferritin encapsulated ascorbic acid (Bio-APOAA) as amplification unit, which were assembled onto the electrodes. The sensing strategy was based on in situ enzymatic hydrolysis of Bio-APOAA to release ascorbic acid (AA) as sacrificial electron donor to produce photocurrent. The photocurrent from the immunosensor was monitored as a result of AFP concentrations. The constructed sensing platform displayed high selectivity and good sensitivity for detecting AFP. Under optimal conditions, a wide linear range from 0.001 to 1000ng/mL and a low detection limit of 0.31pg/mL were obtained. The developed immunosensor is expected to be used to determine AFP and other tumor markers in human plasma in clinical laboratories either for pre-cancer screening or cancer monitoring. Moreover, this sensing platform further has the potential to use for the detection of trypsin activity and the corresponding inhibitor-screening. Copyright © 2017 Elsevier B.V. All rights reserved.

Visible-light-induced two-electron-transfer photoreductions on CdS: Effects of morphology

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

Shiragami, Tsutomu; Pac, Chyongjin; Yanagida, Shozo

1990-01-25

Freshly prepared CdS suspensions (CdS-O) consisting of quantized particles and their loose aggregation catalyze photoreductions of aromatic ketones and olefins in methanol under visible light irradiation using triethylamine as sacrificial electron donor, yielding alcohols and dihydro compounds, respectively, which are more selective than photocatalysis of commercially available crystalline CdS (Aldrich) (CdS-Ald). Deuterium incorporation experiments in photolysis of dimethyl maleate in methanol-O-D revealed that CdS-O catalyzes sequential two-electron-transfer photoreduction, affording dideuterated dimethyl succinate, while CdS-Ald induces both photoreduction and photoisomerization through disproportionation between one-electron-transfer-reduction intermediates, yielding much trideuterated dimethyl succinate and monodeuterated dimethyl fumarate and maleate.

Single-electron quantization at room temperature in a-few-donor quantum dot in silicon nano-transistors

NASA Astrophysics Data System (ADS)

Samanta, Arup; Muruganathan, Manoharan; Hori, Masahiro; Ono, Yukinori; Mizuta, Hiroshi; Tabe, Michiharu; Moraru, Daniel

2017-02-01

Quantum dots formed by donor-atoms in Si nanodevices can provide a breakthrough for functionality at the atomic level with one-by-one control of electrons. However, single-electron effects in donor-atom devices have only been observed at low temperatures mainly due to the low tunnel barriers. If a few donor-atoms are closely coupled as a molecule to form a quantum dot, the ground-state energy level is significantly deepened, leading to higher tunnel barriers. Here, we demonstrate that such an a-few-donor quantum dot, formed by selective conventional doping of phosphorus (P) donors in a Si nano-channel, sustains Coulomb blockade behavior even at room temperature. In this work, such a quantum dot is formed by 3 P-donors located near the center of the selectively-doped area, which is consistent with a statistical analysis. This finding demonstrates practical conditions for atomic- and molecular-level electronics based on donor-atoms in silicon nanodevices.

Improving Efficiency of Aluminium Sacrificial Anode Using Cold Work Process

NASA Astrophysics Data System (ADS)

Asmara, Y. P.; Siregar, J. P.; Tezara, C.; Ann, Chang Tai

2016-02-01

Aluminium is one of the preferred materials to be used as sacrificial anode for carbon steel protection. The efficiency of these can be low due to the formation of oxide layer which passivate the anodes. Currently, to improve its efficiency, there are efforts using a new technique called surface modifications. The objective of this research is to study corrosion mechanism of aluminium sacrificial anode which has been processed by cold work. The cold works are applied by reducing the thickness of aluminium sacrificial anodes at 20% and 40% of thickness reduction. The cathodic protection experiments were performed by immersion of aluminium connected to carbon steel cylinder in 3% NaCl solutions. Visual inspections using SEM had been conducted during the experiments and corrosion rate data were taken in every week for 8 weeks of immersion time. Corrosion rate data were measured using weight loss and linear polarization technique (LPR). From the results, it is observed that cold worked aluminium sacrificial anode have a better corrosion performance. It shows higher corrosion rate and lower corrosion potential. The anodes also provided a long functional for sacrificial anode before it stop working. From SEM investigation, it is shown that cold works have changed the microstructure of anodes which is suspected in increasing corrosion rate and cause de-passivate of the surface anodes.

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.

Fine Splitting of Electron States in Silicon Nanocrystal with a Hydrogen-like Shallow Donor

PubMed Central

2007-01-01

Electron structure of a silicon quantum dot doped with a shallow hydrogen-like donor has been calculated for the electron states above the optical gap. Within the framework of the envelope-function approach we have calculated the fine splitting of the ground sixfold degenerate electron state as a function of the donor position inside the quantum dot. Also, dependence of the wave functions and energies on the dot size was obtained.

Rational Design of an Electron-Reservoir Pt(II) Complex for Efficient Photocatalytic Hydrogen Production from Water.

PubMed

Whang, Dong Ryeol; Park, Soo Young

2015-10-12

Herein we report a Pt(II) complex containing a 4,4'-bis[4-(triphenylsilyl)phenyl]-2,2'-bipyridine ligand as a molecular catalyst for water splitting. Systematic studies of the electrochemical and electronic properties of this catalyst, in comparison with two control complexes, reveal electron-reservoir characteristics upon two-electron reduction. A turnover number of 510,000 was recorded by employing this complex as a water reduction catalyst in combination with a state-of-the-art photosensitizer and N,N-dimethylaniline as a sacrificial electron donor, which represents a large improvement over the control complexes that do not contain the tetraphenylsilyl ligand substitution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HF-Release of Sacrificial Layers in CMOS-integrated MOEMS structures

NASA Astrophysics Data System (ADS)

Döring, S.; Friedrichs, M.; Pufe, W.; Schulze, M.

2016-10-01

In this paper we will present details of the release process of SiO2 sacrificial layers we use within a multi-level MOEMS process developed by IPMS. Using such sacrificial layers gain a lot of benefits necessary for the production of high-end MOEMS devices like high surface quality and great surface planarity. However the HF-release of the sacrificial layer can be connected with specific issues. We present, which mechanisms are involved in the release process and how knowing them, can be the key for an optimized performance of the device. More-over we will present how to protect the CMOS backplane of our devices from unwanted HF attack during the release.

Modular Electron Donor Group Tuning Of Frontier Energy Levels In Diarylaminofluorenone Push-Pull Molecules

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

Homnick, Paul J.; Lahti, P. M.

2012-01-01

Push–pull organic molecules composed of electron donor diarylamines at the 2- and 2,7-positions of fluorenone exhibit intramolecular charge-transfer behaviour in static absorption and emission spectra. Electrochemical and spectral data combined in a modular electronic analysis model show how the donor HOMO and acceptor LUMO act as major determinants of the frontier molecular orbital energy levels.

Method of using sacrificial materials for fabricating internal cavities in laminated dielectric structures

DOEpatents

Peterson, Kenneth A [Albuquerque, NM

2009-02-24

A method of using sacrificial materials for fabricating internal cavities and channels in laminated dielectric structures, which can be used as dielectric substrates and package mounts for microelectronic and microfluidic devices. A sacrificial mandrel is placed in-between two or more sheets of a deformable dielectric material (e.g., unfired LTCC glass/ceramic dielectric), wherein the sacrificial mandrel is not inserted into a cutout made in any of the sheets. The stack of sheets is laminated together, which deforms the sheet or sheets around the sacrificial mandrel. After lamination, the mandrel is removed, (e.g., during LTCC burnout), thereby creating a hollow internal cavity in the monolithic ceramic structure.

Two-electron spin correlations in precision placed donors in silicon.

PubMed

Broome, M A; Gorman, S K; House, M G; Hile, S J; Keizer, J G; Keith, D; Hill, C D; Watson, T F; Baker, W J; Hollenberg, L C L; Simmons, M Y

2018-03-07

Substitutional donor atoms in silicon are promising qubits for quantum computation with extremely long relaxation and dephasing times demonstrated. One of the critical challenges of scaling these systems is determining inter-donor distances to achieve controllable wavefunction overlap while at the same time performing high fidelity spin readout on each qubit. Here we achieve such a device by means of scanning tunnelling microscopy lithography. We measure anti-correlated spin states between two donor-based spin qubits in silicon separated by 16 ± 1 nm. By utilising an asymmetric system with two phosphorus donors at one qubit site and one on the other (2P-1P), we demonstrate that the exchange interaction can be turned on and off via electrical control of two in-plane phosphorus doped detuning gates. We determine the tunnel coupling between the 2P-1P system to be 200 MHz and provide a roadmap for the observation of two-electron coherent exchange oscillations.

Low potential manganese ions as efficient electron donors in native anoxygenic bacteria.

PubMed

Deshmukh, Sasmit S; Protheroe, Charles; Ivanescu, Matei-Alexandru; Lag, Sarah; Kálmán, László

2018-04-01

Systematic control over molecular driving forces is essential for understanding the natural electron transfer processes as well as for improving the efficiency of the artificial mimics of energy converting enzymes. Oxygen producing photosynthesis uniquely employs manganese ions as rapid electron donors. Introducing this attribute to anoxygenic photosynthesis may identify evolutionary intermediates and provide insights to the energetics of biological water oxidation. This work presents effective environmental methods that substantially and simultaneously tune the redox potentials of manganese ions and the cofactors of a photosynthetic enzyme from native anoxygenic bacteria without the necessity of genetic modification or synthesis. A spontaneous coordination with bis-tris propane lowered the redox potential of the manganese (II) to manganese (III) transition to an unusually low value (~400 mV) at pH 9.4 and allowed its binding to the bacterial reaction center. Binding to a novel buried binding site elevated the redox potential of the primary electron donor, a dimer of bacteriochlorophylls, by up to 92 mV also at pH 9.4 and facilitated the electron transfer that is able to compete with the wasteful charge recombination. These events impaired the function of the natural electron donor and made BTP-coordinated manganese a viable model for an evolutionary alternative. Copyright © 2018 Elsevier B.V. All rights reserved.

Single crystalline hollow metal-organic frameworks: a metal-organic polyhedron single crystal as a sacrificial template.

PubMed

Kim, Hyehyun; Oh, Minhak; Kim, Dongwook; Park, Jeongin; Seong, Junmo; Kwak, Sang Kyu; Lah, Myoung Soo

2015-02-28

Single crystalline hollow metal-organic frameworks (MOFs) with cavity dimensions on the order of several micrometers and hundreds of micrometers were prepared using a metal-organic polyhedron single crystal as a sacrificial hard template. The hollow nature of the MOF crystal was confirmed by scanning electron microscopy of the crystal sliced using a focused ion beam.

Longitudinal and transverse spin dynamics of donor-bound electrons in fluorine-doped ZnSe: Spin inertia versus Hanle effect

NASA Astrophysics Data System (ADS)

Heisterkamp, F.; Zhukov, E. A.; Greilich, A.; Yakovlev, D. R.; Korenev, V. L.; Pawlis, A.; Bayer, M.

2015-06-01

The spin dynamics of strongly localized donor-bound electrons in fluorine-doped ZnSe epilayers is studied using pump-probe Kerr rotation techniques. A method exploiting the spin inertia is developed and used to measure the longitudinal spin relaxation time T1 in a wide range of magnetic fields, temperatures, and pump densities. The T1 time of the donor-bound electron spin of about 1.6 μ s remains nearly constant for external magnetic fields varied from zero up to 2.5 T (Faraday geometry) and in a temperature range 1.8-45 K. These findings impose severe restrictions on possible spin relaxation mechanisms. In our opinion they allow us to rule out scattering between free and donor-bound electrons, jumping of electrons between different donor centers, scattering between phonons and donor-bound electrons, and with less certainty charge fluctuations in the environment of the donors caused by the 1.5 ps pulsed laser excitation.

Microfabrication of SrRuO3 thin films on various oxide substrates using LaAlO3/BaOx sacrificial bilayers

NASA Astrophysics Data System (ADS)

Harada, Takayuki; Tsukazaki, Atsushi

2018-02-01

Oxides provide various fascinating physical properties that could find use in future device applications. However, the physical properties of oxides are often affected by formation of oxygen vacancies during device fabrication processes. In this study, to develop a damage-free patterning process for oxides, we focus on a lift-off process using a sacrificial template layer, by which we can pattern oxide thin films without severe chemical treatment or plasma bombardment. As oxides need high thin-film growth temperature, a sacrificial template needs to be made of thermally stable and easily etchable materials. To meet these requirements, we develop a sacrificial template with a carefully designed bilayer structure. Combining a thermally and chemically stable LaAlO3 and a water-soluble BaOx, we fabricated a LaAlO3/BaOx sacrificial bilayer. The patterned LaAlO3/BaOx sacrificial bilayers were prepared on oxide substrates by room-temperature pulsed laser deposition and standard photolithography process. The structure of the sacrificial bilayer can be maintained even in rather tough conditions needed for oxide thin film growth: several hundred degrees Celsius under high oxygen pressure. Indeed, the LaAlO3/BaOx bilayer is easily removable by sonication in water. We applied the lift-off method using the LaAlO3/BaOx sacrificial bilayer to a representative oxide conductor SrRuO3 and fabricated micron-scale Hall-bar devices. The SrRuO3 channels with the narrowest line width of 5 μm exhibit an almost identical transport property to that of the pristine film, evidencing that the developed process is beneficial for patterning oxides. We show that the LaAlO3/BaOx lift-off process is applicable to various oxide substrates: SrTiO3, MgO, and Al2O3. The new versatile patterning process will expand the range of application of oxide thin films in electronic and photonic devices.

Sacrificial component fabrication for optimised production of micro-vascular polymer composite

NASA Astrophysics Data System (ADS)

Dalton, B.; Dixon, D.; McIlhagger, A.; Archer, E.

2015-02-01

Smart functional materials are a viable future goal for advanced applications in aerospace, space and medical applications. In this work micro-vascular polymer composite systems have been developed using sacrificial fibres produced from catalyst loaded Poly(lactic acid). The sacrificial fibres have been produced via a published technique which treated PLA in a solvent catalyst mixture of 60% Trifluoroethanol, 40% H2O dispersed with 10 wt% tin (II) oxalate catalyst. A second process of polymer extrusion of PLA using graded fill contents of tin (II) oxalate has also been developed for the up scaled production of fibres as an alternative to solution treatment. Thermal analysis (TGA) was used to compare sacrificial fibre specimens. PLA fibres produced via the polymer extrusion method outperformed solution treated fibres displaying a lower degradation onset temperature (average 25°C lower), higher degradation rates (observed through a derivative curve comparison) and lower residual catalyst content (0.67% solvent treated fibre against 0.16% extruded fibre). The continuous extrusion process is solvent free and is suitable for high volume production. This work has been carried out to fully understand the fabrication issues with sacrificial components.

Donor-bridge-acceptor energetics determine the distance dependence of electron tunneling in DNA

NASA Astrophysics Data System (ADS)

Lewis, Frederick D.; Liu, Jianqin; Weigel, Wilfried; Rettig, Wolfgang; Kurnikov, Igor V.; Beratan, David N.

2002-10-01

Electron transfer (ET) processes in DNA are of current interest because of their involvement in oxidative strand cleavage reactions and their relevance to the development of molecular electronics. Two mechanisms have been identified for ET in DNA, a single-step tunneling process and a multistep charge-hopping process. The dynamics of tunneling reactions depend on both the distance between the electron donor and acceptor and the nature of the molecular bridge separating the donor and acceptor. In the case of protein and alkane bridges, the distance dependence is not strongly dependent on the properties of the donor and acceptor. In contrast, we show here that the distance decay of DNA ET rates varies markedly with the energetics of the donor and acceptor relative to the bridge. Specifically, we find that an increase in the energy of the bridge states by 0.25 eV (1 eV = 1.602 × 1019 J) relative to the donor and acceptor energies for photochemical oxidation of nucleotides, without changing the reaction free energy, results in an increase in the characteristic exponential distance decay constant for the ET rates from 0.71 to 1.1 Å1. These results show that, in the small tunneling energy gap regime of DNA ET, the distance dependence is not universal; it varies strongly with the tunneling energy gap. These DNA ET reactions fill a "missing link" or transition regime between the large barrier (rapidly decaying) tunneling regime and the (slowly decaying) hopping regime in the general theory of bridge-mediated ET processes.

Non-Sacrificial, Anti-Graffiti Coating 2009 Evaluation

DOT National Transportation Integrated Search

2010-04-01

Graffiti eradication is a problem for the Nevada Department of Transportation (NDOT). Over 12,000 man-hours are spent on graffiti eradication each year. One recognized graffiti abatement method is the use of non-sacrificial, anti-graffiti coating. ND...

Photoinduced electron transfer in fixed distance chlorophyll-quinone donor-acceptor molecules

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

Wasielewski, M.R.; Johnson, D.G.; Svec, W.A.

1987-01-01

A series of fixed distance chlorophyll-quinone donor-acceptor molecules have been prepared. The donor consists of either methyl pyropheophorbide a or methyl pyrochlorophyllide a, while the acceptor is either benzoquinone or naphthoquinone. The acceptors are fused to a triptycene spacer group, which in turn is attached to the donors at their vinyl groups. Picosecond transient absorption measurements have been used to identify electron transfer from the lowest excited singlet state of the donor to the acceptor as the mechanism of fluorescence quenching in these molecules. The charge separation rate constants increase from 2 x 10/sup 10/ s/sup -1/ to 4 xmore » 10/sup 11/ s/sup -1/ as the free energy of charge separation increases, while the radical pair recombination rate constants decrease from 1.2 x 10/sup 11/ s/sup -1/ to 2 x 10/sup 9/ s/sup -1/ as the free energy of recombination increases. The resulting total reorganization energy lambda = 0.9 eV.« less

Chlorine-Resistant Polyamide Reverse Osmosis Membrane with Monitorable and Regenerative Sacrificial Layers.

PubMed

Huang, Hai; Lin, Saisai; Zhang, Lin; Hou, Li'an

2017-03-22

Improving chlorine stability is a high priority for aromatic polyamide (PA) reverse osmosis (RO) membranes especially in long-term desalination. In this Research Article, PA RO membranes of sustainable chlorine resistance was synthesized. Glycylglycine (Gly) was grafted onto the membrane surface as a regenerative chlorine sacrificial layer, and the zeta-potential was used to monitor the membrane performance and to conduct timely regeneration operations for chlorinated Gly. The Gly-grafted PA membrane exhibited ameliorative chlorine resistance in which the N-H moiety of glycylglycine served as sacrificial pendants against chlorine attacks. Cyclic chlorination experiments, combined with FT-IR and XPS analysis, were carried out to characterize the membrane. Results indicated that the resulting N-halamines could be fast regenerated by a simple alkaline reduction step (pH 10). A synchronous relationship between the zeta-potential and the chlorination extent of the sacrificial layer was observed. This indicated that the zeta-potential can be used as an on-site sensor to conduct a timely regeneration operation. The intrinsic mechanism of the surface sacrificial process was also studied.

Effect of samarium in corrosion and microstructure of Al-5Zn-0.5Cu as low driving voltage sacrificial anode

NASA Astrophysics Data System (ADS)

Pratesa, Yudha; Ferdian, Deni; Ramadhan, Fajar Yusya; Maulana, Bramuda

2018-05-01

Sacrificial Anode Low voltage is the latest generation of the sacrificial anode that can prevent the occurrence of Hydrogen Cracking (HIC) due to overprotection. The Al-5n-0.5Cu alloy showed the potential to be developed as the new sacrificial anode. However, the main problem is copper made Al2Cu intermetallic in grain boundary. Samarium is added to modify the shape of the intermetallic to make it finer and make the corrosion uniform. Several characterizations were conducted to analyze the effect of Samarium. Scanning electron microscope (SEM) and Energy dispersive spectroscopy was used to analyzed the microstructure of the alloy. Metallography preparation was prepared for SEM analysis. Corrosion behavior was characterized by cyclic polarization in 3.5% NaCl solution. The results show samarium can change the shape of intermetallic and refine the grains. In addition, samarium makes better pitting resistance and exhibits a tendency for uniform corrosion. It is indicated by the loop reduction (ΔEpit-prot). Current density increased as an effect of samarium addition from 6x10-5 Ampere (Al-5Zn-0.5Cu) to 2.5x10-4 Ampere (Al-5Zn-0.5Cu-0.5Sm). Steel potential protection increased after addition of samarium which is an indication the possibility of Al-Zn-Cu-Sm to be used as low voltage sacrificial anode.

Improving Effectiveness of Bioremediation at DNAPL Source Zone Sites by Applying Partitioning Electron Donors (PEDs)

DTIC Science & Technology

2014-05-01

as trichloroethene (TCE) and tetrachloroethene (PCE). EISB typically relies on the addition of electron donor formulations to enhance the rate of... value (NPV) cost when applied using passive (i.e., biostimulation) methods. Hence, the selection of electron donors has a major implication on EISB...Engineering Service Center NAVFACSW NAVFAC Southwest nBA n-Butyl acetate nBuOH n-Butanol nHEX n-Hexanol NPV net present value O&M operation and

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…

A Sacrificial Coating Strategy Toward Enhancement of Metal-Support Interaction for Ultrastable Au Nanocatalysts

DOE PAGES

Zhan, Wangcheng; He, Qian; Liu, Xiaofei; ...

2016-11-22

Supported gold (Au) nanocatalysts hold great promise for heterogeneous catalysis; however, their practical application is greatly hampered by poor thermodynamic stability. Herein, a general synthetic strategy is reported where discrete metal nanoparticles are made resistant to sintering, preserving their catalytic activities in high-temperature oxidation processes. Taking advantage of the unique coating chemistry of dopamine, sacrificial carbon layers are constructed on the material surface, stabilizing the supported catalyst. Upon annealing at high temperature under an inert atmosphere, the interactions between support and metal nanoparticle are dramatically enhanced, while the sacrificial carbon layers can be subsequently removed through oxidative calcination in air.more » Owing to the improved metal-support contact and strengthened electronic interactions, the resulting Au nanocatalysts are resistant to sintering and exhibit excellent durability for catalytic combustion of propylene at elevated temperatures. Moreover, the facile synthetic strategy can be extended to the stabilization of other supported catalysts on a broad range of supports, providing a general approach to enhancing the thermal stability and sintering resistance of supported nanocatalysts.« less

Effect of sulfate on anaerobic reduction of nitrobenzene with acetate or propionate as an electron donor.

PubMed

Huang, Jingang; Wen, Yue; Ding, Ning; Xu, Yue; Zhou, Qi

2012-09-15

Sulfate is frequently found in wastewaters that contain nitrobenzene. To reveal the effect of sulfate on the reductive transformation of nitrobenzene to aniline--with acetate or propionate as potential electron donors in anaerobic systems--an acetate series (R1-R5) and a propionate series (R6-R10) were set up. Each of these was comprised of five laboratory-scale sequence batch reactors. The two series were amended with the same amount of nitrobenzene and electron donor electron equivalents, whereas with increasing sulfate concentrations. Results indicated that the presence of sulfate could depress nitrobenzene reduction. Such depression is linked to the inhibition of nitroreductase activity and/or the shift of electron flow. In the acetate series, although sulfate did not strongly compete with nitrobenzene for electron donors, noncompetitive inhibition of specific nitrobenzene reduction rates by sulfate was observed, with an inhibition constant of 0.40 mM. Propionate, which can produce intermediate H₂ as preferred reducing equivalent, is a more effective primary electron donor for nitrobenzene reduction as compared to acetate. In the propionate series, sulfate was found to be a preferential electron acceptor as compared to nitrobenzene, resulting in a quick depletion of propionate and then a likely termination of H₂-releasing under higher sulfate concentrations (R9 and R10). In such a situation, nitrobenzene reduction slowed down, occurring two-stage zero-order kinetics. Copyright © 2012 Elsevier Ltd. All rights reserved.

Ultrafast electron transfer in all-carbon-based SWCNT-C60 donor-acceptor nanoensembles connected by poly(phenylene-ethynylene) spacers

NASA Astrophysics Data System (ADS)

Barrejón, Myriam; Gobeze, Habtom B.; Gómez-Escalonilla, María J.; Fierro, José Luis G.; Zhang, Minfang; Yudasaka, Masako; Iijima, Sumio; D'Souza, Francis; Langa, Fernando

2016-08-01

Building all-carbon based functional materials for light energy harvesting applications could be a solution to tackle and reduce environmental carbon output. However, development of such all-carbon based donor-acceptor hybrids and demonstration of photoinduced charge separation in such nanohybrids is a challenge since in these hybrids part of the carbon material should act as an electron donating or accepting photosensitizer while the second part should fulfil the role of an electron acceptor or donor. In the present work, we have successfully addressed this issue by synthesizing covalently linked all-carbon-based donor-acceptor nanoensembles using single-walled carbon nanotubes (SWCNTs) as the donor and C60 as the acceptor. The donor-acceptor entities in the nanoensembles were connected by phenylene-ethynylene spacer units to achieve better electronic communication and to vary the distance between the components. These novel SWCNT-C60 nanoensembles have been characterized by a number of techniques, including TGA, FT-IR, Raman, AFM, absorbance and electrochemical methods. The moderate number of fullerene addends present on the side-walls of the nanotubes largely preserved the electronic structure of the nanotubes. The thermodynamic feasibility of charge separation in these nanoensembles was established using spectral and electrochemical data. Finally, occurrence of ultrafast electron transfer from the excited nanotubes in these donor-acceptor nanohybrids has been established by femtosecond transient absorption studies, signifying their utility in building light energy harvesting devices.Building all-carbon based functional materials for light energy harvesting applications could be a solution to tackle and reduce environmental carbon output. However, development of such all-carbon based donor-acceptor hybrids and demonstration of photoinduced charge separation in such nanohybrids is a challenge since in these hybrids part of the carbon material should act as an

Nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates

DOEpatents

Melechko, Anatoli V [Oak Ridge, TN; McKnight, Timothy E [Greenback, TN; Guillorn, Michael A [Ithaca, NY; Ilic, Bojan [Ithaca, NY; Merkulov, Vladimir I [Knoxville, TN; Doktycz, Mitchel J [Knoxville, TN; Lowndes, Douglas H [Knoxville, TN; Simpson, Michael L [Knoxville, TN

2011-08-23

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoreplicant structure coupled to a surface of the substrate.

When does self-sacrificial leadership motivate prosocial behavior? It depends on followers' prevention focus.

PubMed

De Cremer, David; Mayer, David M; van Dijke, Marius; Bardes, Mary; Schouten, Barbara C

2009-07-01

In the present set of studies, the authors examine the idea that self-sacrificial leadership motivates follower prosocial behavior, particularly among followers with a prevention focus. Drawing on the self-sacrificial leadership literature and regulatory focus theory, the authors provide results from 4 studies (1 laboratory and 3 field studies) that support the research hypothesis. Specifically, the relationship between self-sacrificial leadership and prosocial behavior (i.e., cooperation, organizational citizenship behavior) is stronger among followers who are high in prevention focus. Implications for the importance of taking a follower-centered approach to leadership are discussed.

Fragment charge difference method for estimating donor-acceptor electronic coupling: Application to DNA π-stacks

NASA Astrophysics Data System (ADS)

Voityuk, Alexander A.; Rösch, Notker

2002-09-01

The purpose of this communication is two-fold. We introduce the fragment charge difference (FCD) method to estimate the electron transfer matrix element HDA between a donor D and an acceptor A, and we apply this method to several aspects of hole transfer electronic couplings in π-stacks of DNA, including systems with several donor-acceptor sites. Within the two-state model, our scheme can be simplified to recover a convenient estimate of the electron transfer matrix element HDA=(1-Δq2)1/2(E2-E1)/2 based on the vertical excitation energy E2-E1 and the charge difference Δq between donor and acceptor. For systems with strong charge separation, Δq≳0.95, one should resort to the FCD method. As favorable feature, we demonstrate the stability of the FCD approach for systems which require an approach beyond the two-state model. On the basis of ab initio calculations of various DNA related systems, we compared three approaches for estimating the electronic coupling: the minimum splitting method, the generalized Mulliken-Hush (GMH) scheme, and the FCD approach. We studied the sensitivity of FCD and GMH couplings to the donor-acceptor energy gap and found both schemes to be quite robust; they are applicable also in cases where donor and acceptor states are off resonance. In the application to π-stacks of DNA, we demonstrated for the Watson-Crick pair dimer [(GC),(GC)] how structural changes considerably affect the coupling strength of electron hole transfer. For models of three Watson-Crick pairs, we showed that the two-state model significantly overestimates the hole transfer coupling whereas simultaneous treatment of several states leads to satisfactory results.

The spin relaxation of nitrogen donors in 6H SiC crystals as studied by the electron spin echo method

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

Savchenko, D., E-mail: dariyasavchenko@gmail.com; National Technical University of Ukraine “Kyiv Polytechnic Institute,” Kyiv 03056; Shanina, B.

2016-04-07

We present the detailed study of the spin kinetics of the nitrogen (N) donor electrons in 6H SiC wafers grown by the Lely method and by the sublimation “sandwich method” (SSM) with a donor concentration of about 10{sup 17 }cm{sup −3} at T = 10–40 K. The donor electrons of the N donors substituting quasi-cubic “k1” and “k2” sites (N{sub k1,k2}) in both types of the samples revealed the similar temperature dependence of the spin-lattice relaxation rate (T{sub 1}{sup −1}), which was described by the direct one-phonon and two-phonon processes induced by the acoustic phonons proportional to T and to T{sup 9}, respectively. Themore » character of the temperature dependence of the T{sub 1}{sup −1} for the donor electrons of N substituting hexagonal (“h”) site (N{sub h}) in both types of 6H SiC samples indicates that the donor electrons relax through the fast-relaxing centers by means of the cross-relaxation process. The observed enhancement of the phase memory relaxation rate (T{sub m}{sup −1}) with the temperature increase for the N{sub h} donors in both types of the samples, as well as for the N{sub k1,k2} donors in Lely grown 6H SiC, was explained by the growth of the free electron concentration with the temperature increase and their exchange scattering at the N donor centers. The observed significant shortening of the phase memory relaxation time T{sub m} for the N{sub k1,k2} donors in the SSM grown sample with the temperature lowering is caused by hopping motion of the electrons between the occupied and unoccupied states of the N donors at N{sub h} and N{sub k1,k2} sites. The impact of the N donor pairs, triads, distant donor pairs formed in n-type 6H SiC wafers on the spin relaxation times was discussed.« less

Effect of Copper and Silicon on Al-5%Zn Alloy as a Candidate Low Voltage Sacrificial Anode

NASA Astrophysics Data System (ADS)

Pratesa, Yudha; Ferdian, Deni; Togina, Inez

2017-05-01

One common method used for corrosion protection is a sacrificial anode. Sacrificial anodes that usually employed in the marine environment are an aluminum alloy sacrificial anode, especially Al-Zn-In. However, the electronegativity of these alloys can cause corrosion overprotection and stress cracking (SCC) on a high-strength steel. Therefore, there is a development of the sacrificial anode aluminum low voltage to reduce the risk of overprotection. The addition of alloying elements such as Cu, Si, and Ge will minimize the possibility of overprotection. This study was conducted to analyze the effect of silicon and copper addition in Al-5Zn. The experiment started from casting the sacrificial anode aluminum uses electrical resistance furnace in a graphite crucible in 800°C. The results alloy was analyzed using Optical emission spectroscopy (OES), Differential scanning calorimetry, electrochemical impedance spectroscopy, and metallography. Aluminum alloy with the addition of a copper alloy is the most suitable and efficient to serve as a low-voltage sacrificial anode aluminum. Charge transfer resistivity of copper is smaller than silicon which indicates that the charge transfer between the metal and the electrolyte is easier t to occur. Also, the current potential values in coupling with steel are also in the criteria range of low-voltage aluminum sacrificial anodes.

Lack of a peroxiredoxin suppresses the lethality of cells devoid of electron donors by channelling electrons to oxidized ribonucleotide reductase.

PubMed

Boronat, Susanna; Domènech, Alba; Carmona, Mercè; García-Santamarina, Sarela; Bañó, M Carmen; Ayté, José; Hidalgo, Elena

2017-06-01

The thioredoxin and glutaredoxin pathways are responsible of recycling several enzymes which undergo intramolecular disulfide bond formation as part of their catalytic cycles such as the peroxide scavengers peroxiredoxins or the enzyme ribonucleotide reductase (RNR). RNR, the rate-limiting enzyme of deoxyribonucleotide synthesis, is an essential enzyme relying on these electron flow cascades for recycling. RNR is tightly regulated in a cell cycle-dependent manner at different levels, but little is known about the participation of electron donors in such regulation. Here, we show that cytosolic thioredoxins Trx1 and Trx3 are the primary electron donors for RNR in fission yeast. Unexpectedly, trx1 transcript and Trx1 protein levels are up-regulated in a G1-to-S phase-dependent manner, indicating that the supply of electron donors is also cell cycle-regulated. Indeed, genetic depletion of thioredoxins triggers a DNA replication checkpoint ruled by Rad3 and Cds1, with the final goal of up-regulating transcription of S phase genes and constitutive RNR synthesis. Regarding the thioredoxin and glutaredoxin cascades, one combination of gene deletions is synthetic lethal in fission yeast: cells lacking both thioredoxin reductase and cytosolic dithiol glutaredoxin. We have isolated a suppressor of this lethal phenotype: a mutation at the Tpx1-coding gene, leading to a frame shift and a loss-of-function of Tpx1, the main client of electron donors. We propose that in a mutant strain compromised in reducing equivalents, the absence of an abundant and competitive substrate such as the peroxiredoxin Tpx1 has been selected as a lethality suppressor to favor RNR function at the expense of the non-essential peroxide scavenging function, to allow DNA synthesis and cell growth.

Design of butterfly type organic dye sensitizers with double electron donors: The first principle study

NASA Astrophysics Data System (ADS)

Yang, Zhenqing; Shao, Di; Li, Juan; Tang, Lian; Shao, Changjin

2018-05-01

In this work, we designed a series of butterfly type organic dyes, named ME07-ME13 by introducing such as triphenylamine, phenothiazine, coumarin groups etc. as electron donors and further investigated their absorption spectra using density functional theory (DFT) and time-dependent DFT (TDDFT). All designed dyes cover the entire visible absorption spectrum from 300 to 800 nm. It's fascinating that ME13 molecule has two absorption peak and the molar coefficient of two absorption peaks are above 4.645 × 104 M-1·cm-1. The light absorption area of ME13 exhibits an increment of 16.5-19.1% compared to ME07-ME12. Furthermore, we performed a detailed analysis on their geometrical and electronic properties, including molecular structures, energy levels, light harvesting efficiency (LHE), driving force (ΔGinject), regeneration (ΔGregen),electron dipole moments (μnormal), intermolecular electron transfer and dye/(TiO2)38 system electron transitions. The results of calculation reveal that double coumarin donors in ME13 are promising functional groups for butterfly type organic dye sensitizers. It is expected that the design of double donors can provide a new strategy and guidance for the investigation in high efficiency dye-sensitized devices.

Nuclear-driven electron spin rotations in a coupled silicon quantum dot and single donor system

NASA Astrophysics Data System (ADS)

Harvey-Collard, Patrick; Jacobson, Noah Tobias; Rudolph, Martin; Ten Eyck, Gregory A.; Wendt, Joel R.; Pluym, Tammy; Lilly, Michael P.; Pioro-Ladrière, Michel; Carroll, Malcolm S.

Single donors in silicon are very good qubits. However, a central challenge is to couple them to one another. To achieve this, many proposals rely on using a nearby quantum dot (QD) to mediate an interaction. In this work, we demonstrate the coherent coupling of electron spins between a single 31P donor and an enriched 28Si metal-oxide-semiconductor few-electron QD. We show that the electron-nuclear spin interaction can drive coherent rotations between singlet and triplet electron spin states. Moreover, we are able to tune electrically the exchange interaction between the QD and donor electrons. The combination of single-nucleus-driven rotations and voltage-tunable exchange provides all elements for future all-electrical control of a spin qubit, and requires only a single dot and no additional magnetic field gradients. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Two-electron states of a group-V donor in silicon from atomistic full configuration interactions

NASA Astrophysics Data System (ADS)

Tankasala, Archana; Salfi, Joseph; Bocquel, Juanita; Voisin, Benoit; Usman, Muhammad; Klimeck, Gerhard; Simmons, Michelle Y.; Hollenberg, Lloyd C. L.; Rogge, Sven; Rahman, Rajib

2018-05-01

Two-electron states bound to donors in silicon are important for both two-qubit gates and spin readout. We present a full configuration interaction technique in the atomistic tight-binding basis to capture multielectron exchange and correlation effects taking into account the full band structure of silicon and the atomic-scale granularity of a nanoscale device. Excited s -like states of A1 symmetry are found to strongly influence the charging energy of a negative donor center. We apply the technique on subsurface dopants subjected to gate electric fields and show that bound triplet states appear in the spectrum as a result of decreased charging energy. The exchange energy, obtained for the two-electron states in various confinement regimes, may enable engineering electrical control of spins in donor-dot hybrid qubits.

Electron-donor dopant, method of improving conductivity of polymers by doping therewith, and a polymer so treated

DOEpatents

Liepins, R.; Aldissi, M.

1984-07-27

Polymers with conjugated backbones, both polyacetylene and polyaromatic heterocyclic types, are doped with electron-donor agents to increase their electrical conductivity. The electron-donor agents are either electride dopants made in the presence of lithium or dopants derived from alkalides made in the presence of lithium. The dopants also contain a metal such as cesium and a trapping agent such as a crown ether.

Electron-donor dopant, method of improving conductivity of polymers by doping therewith, and a polymer so treated

DOEpatents

Liepins, Raimond; Aldissi, Mahmoud

1988-01-01

Polymers with conjugated backbones, both polyacetylene and polyaromatic heterocyclic types, are doped with electron-donor agents to increase their electrical conductivity. The electron-donor agents are either electride dopants made in the presence of lithium or dopants derived from alkalides made in the presence of lithium. The dopants also contain a metal such as cesium and a trapping agent such as a crown ether.

Theoretical study of solvent effects on the electronic coupling matrix elements in rigidly linked donor-acceptor systems

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

Cave, R.J.; Newton, M.D.; Kumar, K.

1995-12-07

The recently developed generalized Mulliken-Hush approach for the calculation of the electronic coupling matrix element for electron-transfer processes is applied to two rigidly linked donor-bridge-acceptor systems having dimethoxyanthracene as the donor and a dicarbomethoxycyclobutene unit as the acceptor. The dependence of the electronic coupling matrix element as a function of bridge type is examined with and without solvent molecules present. For clamp-shaped bridge structures solvent can have a dramatic effect on the electronic coupling matrix element. The behavior with variation of solvent is in good agreement with that observed experimentally for these systems. 23 refs., 2 tabs.

Heterogeneous semiconductor photocatalysts for hydrogen production from aqueous solutions of electron donors

NASA Astrophysics Data System (ADS)

Kozlova, E. A.; Parmon, V. N.

2017-09-01

Current views on heterogeneous photocatalysts for visible- and near-UV-light-driven production of molecular hydrogen from water and aqueous solutions of inorganic and organic electron donors are analyzed and summarized. Main types of such photocatalysts and methods for their preparation are considered. Particular attention is paid to semiconductor photocatalysts based on sulfides that are known to be sensitive to visible light. The known methods for increasing the quantum efficiency of the target process are discussed, including design of the structure, composition and texture of semiconductor photocatalysts and variation of the medium pH and the substrate and photocatalyst concentrations. Some important aspects of the activation and deactivation of sulfide photocatalysts and the evolution of their properties in the course of hydrogen production processes in the presence of various types of electron donors are analyzed. The bibliography includes 276 references.

Corrosion control acceptance criteria for sacrificial anode type, cathodic protection systems (user guide)

NASA Astrophysics Data System (ADS)

Hock, Vincent F.; Noble, Michael; McLeod, Malcolm E.

1994-07-01

The Army currently operates and maintains more than 20,000 underground storage tanks and over 3000 miles of underground gas pipelines, all of which require some form of corrosion control. Cathodic protection is one method of corrosion control used to prevent corrosion-induced leaks when a steel structure is exposed to an aggressive soil. The corrosion control acceptance criteria for sacrificial anode type CP systems provides guidelines for the DEH/DPW cathodic protection installation inspectors whose responsibilities are to ensure that the materials and equipment specified are delivered to the job site and subsequently installed in accordance with the engineering drawings and specifications. The sacrificial anode CP acceptance criteria includes all components for the sacrificial anode system such as insulated conductors, anodes, anode backfills, and auxiliary equipment. The sacrificial anode CP acceptance criteria is composed of a checklist that lists each component and that contains a space for the inspector to either check 'yes' or 'no' to indicate whether the component complies with the job specifications. In some cases, the inspector must measure and record physical dimensions or electrical output and compare the measurements to standards shown in attached tables.

Self-Sacrificial Salt Templating: Simple Auxiliary Control over the Nanoporous Structure of Porous Carbon Monoliths Prepared through the Solvothermal Route

PubMed Central

Feng, Junzong; Jiang, Yonggang; Liu, Ping; Zhang, Qiuhua; Wei, Ronghui; Chen, Xiang; Feng, Jian

2018-01-01

The conventional sol-gel method for preparing porous carbons is tedious and high-cost to prepare porous carbons and the control over the nanoporous architecture by solvents and carbonization is restricted. A simple and novel self-sacrificial salt templating method was first presented to adjust the microporous structure of porous carbon monoliths synthesized via the solvothermal method. Apart from good monolithic appearance, the solvothermal route allowed for ambient drying because it made sure that the polymerization reaction was completed quickly and thoroughly. The intact and crack-free porous carbon monoliths were investigated by scanning electron microscopy (SEM), thermogravimetric differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and nitrogen sorption measurements. It was proven that the self-sacrificial salts NH4SCN had been removed during pyrolyzing and so, porous carbon monoliths could be directly obtained after carbonization without the need of washing removal of salts. Most importantly, the microporous specific surface area of the resultant porous carbon monoliths was dramatically increased up to 770 m2/g and the Brunauer–Emmett–Teller (BET) specific surface area was up to 1131 m2/g. That was because the salts NH4SCN as self-sacrificial templating helped to form more around 0.6 nm, 0.72 nm and 1.1 nm micropores. The self-sacrificial salt templating is also a suitable and feasible method for controlling the nanoporous structure of other porous materials. PMID:29671818

Parylene C as a Sacrificial Material for Microfabrication

NASA Technical Reports Server (NTRS)

Beamesderfer, Michael

2005-01-01

Parylene C has been investigated for use as a sacrificial material in microfabrication. Although Parylene C cannot be patterned lithographically like photoresists, it nevertheless extends the range of processing options by offering a set of properties that are suitable for microfabrication and are complementary to those of photoresists. The compatibility of Parylene C with several microfabrication processes was demonstrated in experiments in which a thin film of Parylene C was deposited on a silicon wafer, then several thin metal films were deposited and successfully patterned, utilizing the Parylene C pads as a sacrificial layer. The term "parylene" -- a contraction of "poly(para-xylene)" -- denotes a family of vapor-deposited polymers. In Parylene C (the most common form of parylene), a chlorine atom is substituted for one of the hydrogen atoms on the benzene ring of each para-xylene moiety. Heretofore, parylenes have been used as conformal coating materials in diverse applications.

Development of sacrificial support fixture using deflection analysis

NASA Astrophysics Data System (ADS)

Ramteke, Ashwini M.; Ashtankar, Kishor M.

2018-04-01

Sacrificial support fixtures are the structures used to hold the part during machining while rotating the part about the fourth axis of CNC machining. In Four axis CNC machining part is held in a indexer which is rotated about the fourth axis of rotation. So using traditional fixturing devices to hold the part during machining such as jigs, v blocks and clamping plates needs a several set ups, manufacturing time which increase the cost associated with it. Since the part is rotated about the axis of rotation in four axis CNC machining so using traditional fixturing devices to hold the part while machining we need to reorient the fixture each time for particular orientation of part about the axis of rotation. So our proposed methodology of fixture design eliminates the cost associate with the complicated fixture design for customized parts which in turn reduces the time of manufacturing of the fixtures. But while designing the layout of the fixtures it is found out that the machining the part using four axis CNC machining the accurate machining of the part is directly proportional to the deflection produced in a part. So to machine an accurate part the deflection produced in a part should be minimum. We assume that the deflection produced in a part is a result of the deflection produced in a sacrificial support fixture while machining. So this paper provides the study of the deflection checking in a part machined using sacrificial support fixture by using FEA analysis.

Enhanced reduction of an azo dye using henna plant biomass as a solid-phase electron donor, carbon source, and redox mediator.

PubMed

Huang, Jingang; Chu, Shushan; Chen, Jianjun; Chen, Yi; Xie, Zhengmiao

2014-06-01

The multiple effects of henna plant biomass as a source of carbon, electron donor, and redox mediator (RM) on the enhanced bio-reduction of Orange II (AO7) were investigated. The results indicated that the maximum AO7 reduction rate in the culture with henna powder was ∼6-fold that in the sludge control culture lacking henna. On the one hand, AO7 reduction can be advantageously enhanced by the release of available electron donors; on the other hand, the associated lawsone can act as a fixed RM and play a potential role in shuttling electrons from the released electron donors to the final electron acceptor, AO7. The soluble chemical oxygen demand (SCOD) during each experiment and the FTIR spectra suggested that the weakened AO7 reduction along with the retention of henna powder might not be attributed to the lack of fixed lawsone but rather to the insufficiency of electron donors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Implanted bismuth donors in 28-Si: Process development and electron spin resonance measurements

NASA Astrophysics Data System (ADS)

Weis, C. D.; Lo, C. C.; Lang, V.; George, R. E.; Tyryshkin, A. M.; Bokor, J.; Lyon, S. A.; Morton, J. J. L.; Schenkel, T.

2012-02-01

Spins of donor atoms in silicon are excellent qubit candidates. Isotope engineered substrates provide a nuclear spin free host environment, resulting in long spin coherence times [1,2]. The capability of swapping quantum information between electron and nuclear spins can enable quantum communication and gate operation via the electron spin and quantum memory via the nuclear spin [2]. Spin properties of donor qubit candidates in silicon have been studied mostly for phosphorous and antimony [1-3]. Bismuth donors in silicon exhibit a zero field splitting of 7.4 GHz and have attracted attention as potential nuclear spin memory and spin qubit candidates [4,5] that could be coupled to superconducting resonators [4,6]. We report on progress in the formation of bismuth doped 28-Si epi layers by ion implantation, electrical dopant activation and their study via pulsed electron spin resonance measurements showing narrow linewidths and good coherence times. [4pt] [1] A. M. Tyryshkin, et al. arXiv: 1105.3772 [2] J. J. L. Morton, et al. Nature (2008) [3] T. Schenkel, et al APL 2006; F. R. Bradbury, et al. PRL (2006) [4] R. E. George, et al. PRL (2010) [5] G. W. Morley, et al. Nat Mat (2010) [6] M. Hatridge, et al. PRB (2011), R. Vijay, et al. APL (2010) This work was supported by NSA (100000080295) and DOE (DE-AC02-05CH11231).

Film transfer enabled by nanosheet seed layers on arbitrary sacrificial substrates

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

Dral, A. P.; Nijland, M.; Koster, G.

An approach for film transfer is demonstrated that makes use of seed layers of nanosheets on arbitrary sacrificial substrates. Epitaxial SrTiO{sub 3}, SrRuO{sub 3}, and BiFeO{sub 3} films were grown on Ca{sub 2}Nb{sub 3}O{sub 10} nanosheet seed layers on phlogopite mica substrates. Cleavage of the mica substrates enabled film transfer to flexible polyethylene terephthalate substrates. Electron backscatter diffraction, X-ray diffraction, and atomic force microscopy confirmed that crystal orientation and film morphology remained intact during transfer. The generic nature of this approach is illustrated by growing films on zinc oxide substrates with a nanosheet seed layer. Film transfer to a flexiblemore » substrate was accomplished via acid etching.« less

Toughening elastomers with sacrificial bonds and watching them break.

PubMed

Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

2014-04-11

Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials.

Comparison between acetate and hydrogen as electron donors and implications for the reductive dehalogenation of PCE and TCE.

PubMed

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

2007-10-30

Bioremediation by reductive dehalogenation of groundwater contaminated with tetrachloroethene (PCE) or trichloroethene (TCE) is generally carried out through the addition of a fermentable electron donor such as lactate, benzoate, carbohydrates or vegetable oil. These fermentable donors are converted by fermenting organisms into acetate and hydrogen, either of which might be used by dehalogenating microorganisms. Comparisons were made between H2 and acetate on the rate and extent of reductive dehalogenation of PCE. PCE dehalogenation with H2 alone was complete to ethene, but with acetate alone it generally proceeded only about half as fast and only to cis-1,2-dichloroethene (cDCE). Additionally, acetate was not used as an electron donor in the presence of H2. These findings suggest the fermentable electron donor requirement for PCE dehalogenation to ethene can be reduced up to 50% by separating PCE dehalogenation into two stages, the first of which uses acetate for the conversion of PCE to cDCE, and the second uses H2 for the conversion of cDCE to ethene. This can be implemented with a recycle system in which the fermentable substrate is added down-gradient, where the hydrogen being produced by fermentation effects cDCE conversion into ethene. The acetate produced is recycled up-gradient to achieve PCE conversion into cDCE. With the lower electron donor usage required, potential problems of aquifer clogging, excess methane production, and high groundwater chemical oxygen demand (COD) can be greatly reduced.

Comparison between acetate and hydrogen as electron donors and implications for the reductive dehalogenation of PCE and TCE

NASA Astrophysics Data System (ADS)

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

2007-10-01

Bioremediation by reductive dehalogenation of groundwater contaminated with tetrachloroethene (PCE) or trichloroethene (TCE) is generally carried out through the addition of a fermentable electron donor such as lactate, benzoate, carbohydrates or vegetable oil. These fermentable donors are converted by fermenting organisms into acetate and hydrogen, either of which might be used by dehalogenating microorganisms. Comparisons were made between H 2 and acetate on the rate and extent of reductive dehalogenation of PCE. PCE dehalogenation with H 2 alone was complete to ethene, but with acetate alone it generally proceeded only about half as fast and only to cis-1,2-dichloroethene (cDCE). Additionally, acetate was not used as an electron donor in the presence of H 2. These findings suggest the fermentable electron donor requirement for PCE dehalogenation to ethene can be reduced up to 50% by separating PCE dehalogenation into two stages, the first of which uses acetate for the conversion of PCE to cDCE, and the second uses H 2 for the conversion of cDCE to ethene. This can be implemented with a recycle system in which the fermentable substrate is added down-gradient, where the hydrogen being produced by fermentation effects cDCE conversion into ethene. The acetate produced is recycled up-gradient to achieve PCE conversion into cDCE. With the lower electron donor usage required, potential problems of aquifer clogging, excess methane production, and high groundwater chemical oxygen demand (COD) can be greatly reduced.

Effectiveness of sacrificial anodes in high-resistivity shotcrete repairs.

DOT National Transportation Integrated Search

2005-01-01

This study investigated the use of discrete sacrificial anodes to improve the durability and extend the life of a shotcrete patch repair in a column. Three columns were used in the investigation. In two columns, anodes were placed around the perimete...

Electron donor concentrations in sediments and sediment properties at the agricultural chemicals team research site near New Providence, Iowa, 2006-07

USGS Publications Warehouse

Maharjan, Bijesh; Korom, Scott F.; Smith, Erik A.

2013-01-01

The concentrations of electron donors in aquifer sediments are important to the understanding of the fate and transport of redox-sensitive constituents in groundwater, such as nitrate. For a study by the U.S. Geological Survey National Water-Quality Assessment Program, 50 sediment samples were collected from below the water table from 11 boreholes at the U.S. Geological Survey Agricultural Chemicals Team research site near New Providence, Iowa, during 2006-07. All samples were analyzed for gravel, sand (coarse, medium, and fine), silt, clay, Munsell soil color, inorganic carbon content, and for the following electron donors: organic carbon, ferrous iron, and inorganic sulfide. A subset of 14 sediment samples also was analyzed for organic sulfur, but all of these samples had concentrations less than the method detection limit; therefore, the presence of this potential electron donor was not considered further. X-ray diffraction analyses provided important semi-quantitative information of well-crystallized dominant minerals within the sediments that might be contributing electron donors.

Electronic states and optical properties of single donor in GaN conical quantum dot with spherical edge

NASA Astrophysics Data System (ADS)

El Aouami, A.; Feddi, E.; El-Yadri, M.; Aghoutane, N.; Dujardin, F.; Duque, C. A.; Phuc, Huynh Vinh

2018-02-01

In this paper we present a theoretical investigation of quantum confinement effects on the electron and single donor states in GaN conical quantum dot with spherical edge. In the framework of the effective mass approximation, the Schrödinger equations of electron and donor have been solved analytically in an infinite potential barrier model. Our calculations show that the energies of electron and donor impurity are affected by the two characteristic parameters of the structure which are the angle Ω and the radial dimension R. We show that, despite the fact that the reduction of the two parameters Ω and R leads to the same confinement effects, the energy remains very sensitive to the variation of the radial part than the variation of the angular part. The analysis of the photoionization cross-section corresponding to optical transitions between the conduction band and the first donor energy level shows clearly that the reduction of the radius R causes a shift in resonance peaks towards the high energies. On the other hand, the optical transitions between 1 s - 1 p , 1 p - 1 d and 1 p - 2 s show that the increment of the conical aperture Ω (or reduction of R) implies a displacement of the excitation energy to higher energies.

Methods of producing free-standing semiconductors using sacrificial buffer layers and recyclable substrates

DOEpatents

Ptak, Aaron Joseph; Lin, Yong; Norman, Andrew; Alberi, Kirstin

2015-05-26

A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices. The low-defect density semiconductor materials produced using this method result in the enhanced performance of the semiconductor devices that incorporate the semiconductor materials.

Enhanced phenol-photodegradation by particulate semiconductor mixtures: interparticle electron-jump.

PubMed

Karunakaran, C; Dhanalakshmi, R; Gomathisankar, P; Manikandan, G

2010-04-15

Degradation of phenol on suspended TiO(2), ZnO, CdO, Fe(2)O(3), CuO, ZnS and Nb(2)O(5) particles under UV-A light exhibit identical photokinetic behavior; follow first-order kinetics, display linear dependence on the photon flux and slowdown with increase of pH. All the semiconductors show sustainable photocatalytic activity. Dissolved O(2) is essential for the photodegradation and oxidizing agents like H(2)O(2), Na(2)BO(3), K(2)S(2)O(8), KBrO(3), KIO(3) and KIO(4), reducing agents such as NaNO(2) and Na(2)SO(3) and sacrificial electron donors like hydroquinone, diphenyl amine and trimethyl amine enhance the degradation. However, the photocatalysis is insensitive to pre-sonication. Two particulate semiconductors present together, under suspension and at continuous motion, enhance the photocatalytic degradation up to about four-fold revealing interparticle electron-jump. 2009 Elsevier B.V. All rights reserved.

Selective etchant for oxide sacrificial material in semiconductor device fabrication

DOEpatents

Clews, Peggy J.; Mani, Seethambal S.

2005-05-17

An etching composition and method is disclosed for removing an oxide sacrificial material during manufacture of semiconductor devices including micromechanical, microelectromechanical or microfluidic devices. The etching composition and method are based on the combination of hydrofluoric acid (HF) and sulfuric acid (H.sub.2 SO.sub.4). These acids can be used in the ratio of 1:3 to 3:1 HF:H.sub.2 SO.sub.4 to remove all or part of the oxide sacrificial material while providing a high etch selectivity for non-oxide materials including polysilicon, silicon nitride and metals comprising aluminum. Both the HF and H.sub.2 SO.sub.4 can be provided as "semiconductor grade" acids in concentrations of generally 40-50% by weight HF, and at least 90% by weight H.sub.2 SO.sub.4.

Photocatalysis using a Wide Range of the Visible Light Spectrum: Hydrogen Evolution from Doped AgGaS2.

PubMed

Yamato, Kohei; Iwase, Akihide; Kudo, Akihiko

2015-09-07

Doping of nickel into AgGaS2 yields a new absorption band, at a wavelength longer than the intrinsic absorption band of the AgGaS2 host. The doped nickel forms an electron donor level in a forbidden band of AgGaS2 . The nickel-doped AgGaS2 with rhodium co-catalyst shows photocatalytic activity for sacrificial H2 evolution under the light of up to 760 nm due to the transition from the electron donor level consisting of Ni(2+) to the conduction band of AgGaS2 . Apparent quantum yields for the sacrificial H2 evolution at 540-620 nm are about 1 %. Moreover, the nickel-doped AgGa0.75 In0.25 S2 also responds to near-IR light, up to 900 nm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sidetracked by trolleys: Why sacrificial moral dilemmas tell us little (or nothing) about utilitarian judgment.

PubMed

Kahane, Guy

2015-01-01

Research into moral decision-making has been dominated by sacrificial dilemmas where, in order to save several lives, it is necessary to sacrifice the life of another person. It is widely assumed that these dilemmas draw a sharp contrast between utilitarian and deontological approaches to morality, and thereby enable us to study the psychological and neural basis of utilitarian judgment. However, it has been previously shown that some sacrificial dilemmas fail to present a genuine contrast between utilitarian and deontological options. Here, I raise deeper problems for this research paradigm. Even when sacrificial dilemmas present a contrast between utilitarian and deontological options at a philosophical level, it is misleading to interpret the responses of ordinary folk in these terms. What is currently classified as "utilitarian judgment" does not in fact share essential features of a genuine utilitarian outlook, and is better explained in terms of commonsensical moral notions. When subjects deliberate about such dilemmas, they are not deciding between opposing utilitarian and deontological solutions, but engaging in a richer process of weighing opposing moral reasons. Sacrificial dilemmas therefore tell us little about utilitarian decision-making. An alternative approach to studying proto-utilitarian tendencies in everyday moral thinking is proposed.

Photoinduced electron transfer interaction of anthraquinones with aniline quenchers: Influence of methyl substitution in aniline donors

NASA Astrophysics Data System (ADS)

Sivakumar, V.; Ponnamma, Deepalekshmi; Hussein, Yasser H. A.

2017-02-01

Photoinduced electron transfer between triplet state of 9,10-anthraquinone (AQ) and its two derivatives: 2-chloro-9,10-anthraquinone (CAQ) and sodium anthraquinone-2-sulfonate (AQS) and ground state aniline (AN) and its dimethyl substitutions: 2,3-dimethylaniline (2,3-DMA), 2,6-dimethylaniline (2,6-DMA), 3,5-dimethylaniline (3,5-DMA) and N,N-dimethylaniline (N,N-DMA) is studied using nanosecond laser flash photolysis at room temperature. Detection of radical bands of quinone anions and aniline cations along with their formation and/or decay kinetics are used to confirm the electron transfer (ET) process. In MeCN medium, AN quenches the triplet state of CAQ (CAQT) but not the triplets AQT or AQST. However in aqueous medium, AN quenches AQST and forms radical ion pair. All the DMAs can react through ET with all the triplet quinones at different degrees of efficiency in MeCN medium. Noticeably, the ring substituted DMAs are less efficient in electron donation to AQT or AQST while the N,N-DMA shows high efficiency in donating electron to all triplet quinones in MeCN medium. Charge distribution of donor molecules, in MeCN medium is calculated using density functional theory (DFT), and shows an enhancement of electron density of the ring of N,N-DMA, making it an ideal electron donor for ET studies compared to other DMAs. This systematic selection and usage of anilines with electrochemically tunable quinones can be viewed as a working model of donor-acceptor system that can be utilized in photoinduced ET applications.

Hot utilitarianism and cold deontology: Insights from a response patterns approach to sacrificial and real world dilemmas.

PubMed

Rosas, Alejandro; Viciana, Hugo; Caviedes, Esteban; Arciniegas, Alejandra

2018-04-18

Research on moral judgment with moral dilemmas suggests that "utilitarian" responses (UR) to sacrificial high-conflict dilemmas are due to decreased harm aversion, not only in individuals with clinical conditions, but also in healthy participants with high scores in antisocial personality traits. We investigated the patterns of responses to different dilemma types in healthy participants and present evidence that some URs to sacrificial dilemmas are morally motivated, as indicated by their empathic concern (EC) or primary psychopathy (PP) scores. In study 1 (N = 230) we tested students with four categories of sacrificial dilemmas featuring innocent victims. In study 2 (N = 590) we tested students with two categories of sacrificial dilemmas and two "real-world" moral dilemmas, where the agent can improve the lot of strangers by making a personal sacrifice. Results in both studies showed no decreased harm aversion in a pattern where the only UR is to the sacrificial dilemma where the number of saved people is very high, and significantly lower harm aversion only in the pattern of all-deontological respondents in Study 2. The analysis by response patterns allowed a better discrimination of the moral motivations of participants and showed that at least some of them express moral concerns in their URs.

Organic photovoltaic cells based on unconventional electron donor fullerene and electron acceptor copper hexadecafluorophthalocyanine

NASA Astrophysics Data System (ADS)

Yang, J. L.; Sullivan, P.; Schumann, S.; Hancox, I.; Jones, T. S.

2012-01-01

We demonstrate organic discrete heterojunction photovoltaic cells based on fullerene (C60) and copper hexadecafluorophthalocyanine (F16CuPc), in which the C60 and F16CuPc act as the electron donor and the electron acceptor, respectively. The C60/F16CuPc cells fabricated with conventional and inverted architectures both exhibit comparable power conversion efficiencies. Furthermore, we show that the photocurrent in both cells is generated by a conventional exciton dissociation mechanism rather than the exciton recombination mechanism recently proposed for a similar C60/F16ZnPc system [Song et al., J. Am. Chem. Soc. 132, 4554 (2010)]. These results demonstrate that new unconventional material systems are a potential way to fabricate organic photovoltaic cells with inverted as well as conventional architectures.

Photoinduced electron transfer in rigidly linked dimethoxynapthalene-N-methylpyridinium donor-acceptor molecules

NASA Astrophysics Data System (ADS)

Clayton, Andrew H. A.; Ghiggino, Kenneth P.; Wilson, Gerard J.; Keyte, Peter J.; Paddon-Row, Michael N.

1992-07-01

Photoinduced electron transfer (ET) is studied in a series of novel molecules containing a dimethoxynaphthalene (DMN) donor and either a pyridine (P) or N-methylpyridinium (P-Me +) acceptor covalently linked via a rigid nonbornalogous bridge ( n sigma bonds in length). ET rates of the order of 10 10 s -1 were measured for the DMN- n-P-Me + series ( n = 4, 6), while no appreciable ET was observed for the DMN- n-P compounds. Electronic and nuclear factors are discussed and the results rationalized in terms of Marcus—Hush and non-adiabatic ET theories.

Tumor cell membrane-targeting pH-dependent electron donor-acceptor fluorescence systems with low background signals.

PubMed

Han, Liang; Liu, Mingming; Ye, Deyong; Zhang, Ning; Lim, Ed; Lu, Jing; Jiang, Chen

2014-03-01

Minimizing the background signal is crucial for developing tumor-imaging techniques with sufficient specificity and sensitivity. Here we use pH difference between healthy tissues and tumor and tumor targeting delivery to achieve this goal. We synthesize fluorophore-dopamine conjugate as pH-dependent electron donor-acceptor fluorescence system. Fluorophores are highly sensitive to electron-transfer processes, which can alter their optical properties. The intrinsic redox properties of dopamine are oxidation of hydroquinone to quinone at basic pH and reduction of quinone to hydroquinone at acidic pH. Quinone can accept electron then quench fluorescence. We design tumor cell membrane-targeting carrier for delivery. We demonstrate quenched fluorophore-quinone can be specially transferred to tumor extracellular environment and tumor-accumulated fluorophore can be activated by acidic pH. These tumor-targeting pH-dependent electron donor-acceptor fluorescence systems may offer new opportunity for developing tumor-imaging techniques. Copyright © 2014 Elsevier Ltd. All rights reserved.

Algae as an electron donor promoting sulfate reduction for the bioremediation of acid rock drainage.

PubMed

Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, Jim A

2016-11-05

This study assessed bioremediation of acid rock drainage in simulated permeable reactive barriers (PRB) using algae, Chlorella sorokiniana, as the sole electron donor for sulfate-reducing bacteria. Lipid extracted algae (LEA), the residues of biodiesel production, were compared with whole cell algae (WCA) as an electron donor to promote sulfate-reducing activity. Inoculated columns containing anaerobic granular sludge were fed a synthetic medium containing H2SO4 and Cu(2+). Sulfate, sulfide, Cu(2+) and pH were monitored throughout the experiment of 123d. Cu recovered in the column packing at the end of the experiment was evaluated using sequential extraction. Both WCA and LEA promoted 80% of sulfate removal (12.7mg SO4(2-) d(-1)) enabling near complete Cu removal (>99.5%) and alkalinity generation raising the effluent pH to 6.5. No noteworthy sulfate reduction, alkalinity formation and Cu(2+) removal were observed in the endogenous control. In algae amended-columns, Cu(2+) was precipitated with biogenic H2S produced by sulfate reduction. Formation of CuS was evidenced by sequential extraction and X-ray diffraction. LEA and WCA provided similar levels of electron donor based on the COD balance. The results demonstrate an innovative passive remediation system using residual algae biomass from the biodiesel industry. Copyright © 2016 Elsevier B.V. All rights reserved.

Sidetracked by trolleys: Why sacrificial moral dilemmas tell us little (or nothing) about utilitarian judgment

PubMed Central

Kahane, Guy

2015-01-01

Research into moral decision-making has been dominated by sacrificial dilemmas where, in order to save several lives, it is necessary to sacrifice the life of another person. It is widely assumed that these dilemmas draw a sharp contrast between utilitarian and deontological approaches to morality, and thereby enable us to study the psychological and neural basis of utilitarian judgment. However, it has been previously shown that some sacrificial dilemmas fail to present a genuine contrast between utilitarian and deontological options. Here, I raise deeper problems for this research paradigm. Even when sacrificial dilemmas present a contrast between utilitarian and deontological options at a philosophical level, it is misleading to interpret the responses of ordinary folk in these terms. What is currently classified as “utilitarian judgment” does not in fact share essential features of a genuine utilitarian outlook, and is better explained in terms of commonsensical moral notions. When subjects deliberate about such dilemmas, they are not deciding between opposing utilitarian and deontological solutions, but engaging in a richer process of weighing opposing moral reasons. Sacrificial dilemmas therefore tell us little about utilitarian decision-making. An alternative approach to studying proto-utilitarian tendencies in everyday moral thinking is proposed. PMID:25791902

Photoinduced electron transfer interaction of anthraquinones with aniline quenchers: Influence of methyl substitution in aniline donors.

PubMed

Sivakumar, V; Ponnamma, Deepalekshmi; Hussein, Yasser H A

2017-02-15

Photoinduced electron transfer between triplet state of 9,10-anthraquinone (AQ) and its two derivatives: 2-chloro-9,10-anthraquinone (CAQ) and sodium anthraquinone-2-sulfonate (AQS) and ground state aniline (AN) and its dimethyl substitutions: 2,3-dimethylaniline (2,3-DMA), 2,6-dimethylaniline (2,6-DMA), 3,5-dimethylaniline (3,5-DMA) and N,N-dimethylaniline (N,N-DMA) is studied using nanosecond laser flash photolysis at room temperature. Detection of radical bands of quinone anions and aniline cations along with their formation and/or decay kinetics are used to confirm the electron transfer (ET) process. In MeCN medium, AN quenches the triplet state of CAQ (CAQ T ) but not the triplets AQ T or AQS T . However in aqueous medium, AN quenches AQS T and forms radical ion pair. All the DMAs can react through ET with all the triplet quinones at different degrees of efficiency in MeCN medium. Noticeably, the ring substituted DMAs are less efficient in electron donation to AQ T or AQS T while the N,N-DMA shows high efficiency in donating electron to all triplet quinones in MeCN medium. Charge distribution of donor molecules, in MeCN medium is calculated using density functional theory (DFT), and shows an enhancement of electron density of the ring of N,N-DMA, making it an ideal electron donor for ET studies compared to other DMAs. This systematic selection and usage of anilines with electrochemically tunable quinones can be viewed as a working model of donor-acceptor system that can be utilized in photoinduced ET applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Estimation of electronic coupling in π-stacked donor-bridge-acceptor systems: Correction of the two-state model

NASA Astrophysics Data System (ADS)

Voityuk, Alexander A.

2006-02-01

Comparison of donor-acceptor electronic couplings calculated within two-state and three-state models suggests that the two-state treatment can provide unreliable estimates of Vda because of neglecting the multistate effects. We show that in most cases accurate values of the electronic coupling in a π stack, where donor and acceptor are separated by a bridging unit, can be obtained as Ṽda=(E2-E1)μ12/Rda+(2E3-E1-E2)2μ13μ23/Rda2, where E1, E2, and E3 are adiabatic energies of the ground, charge-transfer, and bridge states, respectively, μij is the transition dipole moments between the states i and j, and Rda is the distance between the planes of donor and acceptor. In this expression based on the generalized Mulliken-Hush approach, the first term corresponds to the coupling derived within a two-state model, whereas the second term is the superexchange correction accounting for the bridge effect. The formula is extended to bridges consisting of several subunits. The influence of the donor-acceptor energy mismatch on the excess charge distribution, adiabatic dipole and transition moments, and electronic couplings is examined. A diagnostic is developed to determine whether the two-state approach can be applied. Based on numerical results, we showed that the superexchange correction considerably improves estimates of the donor-acceptor coupling derived within a two-state approach. In most cases when the two-state scheme fails, the formula gives reliable results which are in good agreement (within 5%) with the data of the three-state generalized Mulliken-Hush model.

Estimation of electronic coupling in pi-stacked donor-bridge-acceptor systems: correction of the two-state model.

PubMed

Voityuk, Alexander A

2006-02-14

Comparison of donor-acceptor electronic couplings calculated within two-state and three-state models suggests that the two-state treatment can provide unreliable estimates of V(da) because of neglecting the multistate effects. We show that in most cases accurate values of the electronic coupling in a pi stack, where donor and acceptor are separated by a bridging unit, can be obtained as V(da) = (E(2)-E(1))mu(12)R(da) + (2E(3)-E(1)-E(2))2mu(13)mu(23)R(da) (2), where E(1), E(2), and E(3) are adiabatic energies of the ground, charge-transfer, and bridge states, respectively, mu(ij) is the transition dipole moments between the states i and j, and R(da) is the distance between the planes of donor and acceptor. In this expression based on the generalized Mulliken-Hush approach, the first term corresponds to the coupling derived within a two-state model, whereas the second term is the superexchange correction accounting for the bridge effect. The formula is extended to bridges consisting of several subunits. The influence of the donor-acceptor energy mismatch on the excess charge distribution, adiabatic dipole and transition moments, and electronic couplings is examined. A diagnostic is developed to determine whether the two-state approach can be applied. Based on numerical results, we showed that the superexchange correction considerably improves estimates of the donor-acceptor coupling derived within a two-state approach. In most cases when the two-state scheme fails, the formula gives reliable results which are in good agreement (within 5%) with the data of the three-state generalized Mulliken-Hush model.

Donor acceptor electronic couplings in π-stacks: How many states must be accounted for?

NASA Astrophysics Data System (ADS)

Voityuk, Alexander A.

2006-04-01

Two-state model is commonly used to estimate the donor-acceptor electronic coupling Vda for electron transfer. However, in some important cases, e.g. for DNA π-stacks, this scheme fails to provide accurate values of Vda because of multistate effects. The Generalized Mulliken-Hush method enables a multistate treatment of Vda. In this Letter, we analyze the dependence of calculated electronic couplings on the number of the adiabatic states included in the model. We suggest a simple scheme to determine this number. The superexchange correction of the two-state approximation is shown to provide good estimates of the electronic coupling.

Enhanced biodegradation of hexachlorocyclohexane in upflow anaerobic sludge blanket reactor using methanol as an electron donor.

PubMed

Bhatt, Praveena; Kumar, M Suresh; Mudliar, Sandeep; Chakrabarti, Tapan

2008-05-01

Anaerobic dechlorination of technical grade hexachlorocyclohexane (THCH) was studied in a continuous upflow anaerobic sludge blanket (UASB) reactor with methanol as a supplementary substrate and electron donor. A reactor without methanol served as the experimental control. The inlet feed concentration of THCH in both the experimental and the control UASB reactor was 100 mg l(-1). After 60 days of continuous operation, the removal of THCH was >99% in the methanol-supplemented reactor as compared to 20-35% in the control reactor. THCH was completely dechlorinated in the methanol fed reactor at 48 h HRT after 2 months of continuous operation. This period was also accompanied by increase in biomass in the reactor, which was not observed in the experimental control. Batch studies using other supplementary substrates as well as electron donors namely acetate, butyrate, formate and ethanol showed lower % dechlorination (<85%) and dechlorination rates (<3 mg g(-1)d(-1)) as compared to methanol (98%, 5 mg g(-1)d(-1)). The optimum concentration of methanol required, for stable dechlorination of THCH (100 mg l(-1)) in the UASB reactor, was found to be 500 mg l(-1). Results indicate that addition of methanol as electron donor enhances dechlorination of THCH at high inlet concentration, and is also required for stable UASB reactor performance.

Gradient ascent pulse engineering approach to CNOT gates in donor electron spin quantum computing

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

Tsai, D.-B.; Goan, H.-S.

2008-11-07

In this paper, we demonstrate how gradient ascent pulse engineering (GRAPE) optimal control methods can be implemented on donor electron spin qubits in semiconductors with an architecture complementary to the original Kane's proposal. We focus on the high fidelity controlled-NOT (CNOT) gate and we explicitly find the digitized control sequences for a controlled-NOT gate by optimizing its fidelity using the effective, reduced donor electron spin Hamiltonian with external controls over the hyperfine A and exchange J interactions. We then simulate the CNOT-gate sequence with the full spin Hamiltonian and find that it has an error of 10{sup -6} that ismore » below the error threshold of 10{sup -4} required for fault-tolerant quantum computation. Also the CNOT gate operation time of 100 ns is 3 times faster than 297 ns of the proposed global control scheme.« less

A sacrificial process for fabrication of biodegradable polymer membranes with submicron thickness.

PubMed

Beardslee, Luke A; Stolwijk, Judith; Khaladj, Dimitrius A; Trebak, Mohamed; Halman, Justin; Torrejon, Karen Y; Niamsiri, Nuttawee; Bergkvist, Magnus

2016-08-01

A new sacrificial molding process using a single mask has been developed to fabricate ultrathin 2-dimensional membranes from several biocompatible polymeric materials. The fabrication process is similar to a sacrificial microelectromechanical systems (MEMS) process flow, where a mold is created from a material that can be coated with a biodegradable polymer and subsequently etched away, leaving behind a very thin polymer membrane. In this work, two different sacrificial mold materials, silicon dioxide (SiO2 ) and Liftoff Resist (LOR) were used. Three different biodegradable materials; polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), and polyglycidyl methacrylate (PGMA), were chosen as model polymers. We demonstrate that this process is capable of fabricating 200-500 nm thin, through-hole polymer membranes with various geometries, pore-sizes and spatial features approaching 2.5 µm using a mold fabricated via a single contact photolithography exposure. In addition, the membranes can be mounted to support rings made from either SU8 or PCL for easy handling after release. Cell culture compatibility of the fabricated membranes was evaluated with human dermal microvascular endothelial cells (HDMECs) seeded onto the ultrathin porous membranes, where the cells grew and formed confluent layers with well-established cell-cell contacts. Furthermore, human trabecular meshwork cells (HTMCs) cultured on these scaffolds showed similar proliferation as on flat PCL substrates, further validating its compatibility. All together, these results demonstrated the feasibility of our sacrificial fabrication process to produce biocompatible, ultra-thin membranes with defined microstructures (i.e., pores) with the potential to be used as substrates for tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1192-1201, 2016. © 2015 Wiley Periodicals, Inc.

High-Fidelity Rapid Initialization and Read-Out of an Electron Spin via the Single Donor D(-) Charge State.

PubMed

Watson, T F; Weber, B; House, M G; Büch, H; Simmons, M Y

2015-10-16

We demonstrate high-fidelity electron spin read-out of a precision placed single donor in silicon via spin selective tunneling to either the D(+) or D(-) charge state of the donor. By performing read-out at the stable two electron D(0)↔D(-) charge transition we can increase the tunnel rates to a nearby single electron transistor charge sensor by nearly 2 orders of magnitude, allowing faster qubit read-out (1 ms) with minimum loss in read-out fidelity (98.4%) compared to read-out at the D(+)↔D(0) transition (99.6%). Furthermore, we show that read-out via the D(-) charge state can be used to rapidly initialize the electron spin qubit in its ground state with a fidelity of F(I)=99.8%.

Understanding the Charge Transfer at the Interface of Electron Donors and Acceptors: TTF–TCNQ as an Example

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

Park, Changwon; Atalla, Viktor; Smith, Sean

Charge transfer between an electron donor and an electron acceptor is widely accepted as being independent of their relative configurations if the interaction between them is weak; however, the limit of this concept for an interacting system has not yet been well established. Our study of prototypical electron donor–acceptor molecules, tetrathiafulvalene–tetracyanoquinodimethane, using density functional theory based on an advanced functional, clearly demonstrates that for interacting molecules, their configurational arrangement is as important as their individual electronic properties in the asymptotic limit to determine the charge transfer direction. For the first time, we demonstrate that by changing their relative orientation, onemore » can reverse the charge transfer direction of the pair, causing the molecules to exchange roles as donor and acceptor. In conclusion, our theory has important implications for understanding the interfacial charge-transfer mechanism of hybrid systems and related phenomena.« less

Understanding the Charge Transfer at the Interface of Electron Donors and Acceptors: TTF–TCNQ as an Example

DOE PAGES

Park, Changwon; Atalla, Viktor; Smith, Sean; ...

2017-06-16

Charge transfer between an electron donor and an electron acceptor is widely accepted as being independent of their relative configurations if the interaction between them is weak; however, the limit of this concept for an interacting system has not yet been well established. Our study of prototypical electron donor–acceptor molecules, tetrathiafulvalene–tetracyanoquinodimethane, using density functional theory based on an advanced functional, clearly demonstrates that for interacting molecules, their configurational arrangement is as important as their individual electronic properties in the asymptotic limit to determine the charge transfer direction. For the first time, we demonstrate that by changing their relative orientation, onemore » can reverse the charge transfer direction of the pair, causing the molecules to exchange roles as donor and acceptor. In conclusion, our theory has important implications for understanding the interfacial charge-transfer mechanism of hybrid systems and related phenomena.« less

Increasing Saturated Electron-Drift Velocity in Donor-Acceptor Doped pHEMT Heterostructures

NASA Astrophysics Data System (ADS)

Protasov, D. Yu.; Gulyaev, D. V.; Bakarov, A. K.; Toropov, A. I.; Erofeev, E. V.; Zhuravlev, K. S.

2018-03-01

Field dependences of the electron-drift velocity in typical pseudomorphic high-electron-mobility transistor (pHEMT) heteroepitaxial structures (HESs) and in those with donor-acceptor doped (DApHEMT) heterostructures with quantum-well (QW) depth increased by 0.8-0.9 eV with the aid of acceptor layers have been studied by a pulsed technique. It is established that the saturated electron-drift velocity in DA-pHEMT-HESs is 1.2-1.3 times greater than that in the usual pHEMT-HESs. The electroluminescence (EL) spectra of DA-pHEMT-HESs do not contain emission bands related to the recombination in widebandgap layers (QW barriers). The EL intensity in these HESs is not saturated with increasing electric field. This is indicative of a suppressed real-space transfer of hot electrons from QW to barrier layers, which accounts for the observed increase in the saturated electron-drift velocity.

Characterization of U(VI) reduction in contaminated sediments with slow-degrading electron donor source

NASA Astrophysics Data System (ADS)

Wu, W.; Watson, D. B.; Zhang, G.; Mehlhorn, T.; Lowe, K.; Earles, J.; Phillips, J.; Kelly, S. D.; Boyanov, M.; Kemner, K. M.; Schadt, C.; Criddle, C. S.; Jardine, P. M.; Brooks, S. C.

2011-12-01

In order to select sustainable, high efficiency and cost effective electron donor source, oleate and emulsified vegetable oil (EVO) were tested uranium (VI) reduction in comparison with ethanol in microcosms using uranium contaminated sediments and groundwater from the US DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) site. The effect of initial sulfate concentration on U(VI) reduction was also tested. Both oleate and EVO were effective electron donor sources for U(VI) reduction. Accumulation of acetate as a major product and the removal of aqueous U(VI) were observed and were associated with sulfate reduction. Both oleate and EVO supported U(VI) reduction but at slower rates with a comparable but slightly lower extent of reduction than ethanol. X-ray absorption near-edge spectroscopy (XANES) analysis confirmed reduction of U(VI) to U(IV). The extent of U(VI) reduction in solid phase was negatively influenced by aqueous calcium concentration. The majority of electrons of the three substrates were consumed by sulfate reduction, Fe(III) reduction, and methanogenesis. Initial U(VI) concentration in the aqueous phase increased with increased sulfate concentration (1 versus 5 mM), likely due to U(VI) desorption from the solid phase. At the higher initial sulfate concentration more U(VI) was reduced and fewer electrons were used in methanogenesis. Analysis of bacterial and archeal populations using 16S rRNA gene libraries showed a significant increase in Deltaproteobacteria after biostimulation. The microbial community structures developed with oleate and EVO were significantly distinct from those developed with ethanol. Bacteria similar to Desulforegula spp. was predominant for oleate and EVO degradation but were not observed in ethanol-amended microcosms. Known U(VI)-reducing bacteria in the microcosms amended with the three electron donor sources included iron(III) reducing Geobacter spp. but in lower abundances than sulfate-reducing Desulfovibrio spp. The

[KEEPING THE ELECTRON-DONOR PROPERTIES OF DRINKING WATER].

PubMed

Gibert, K K; Stekhin, A A; Iakovleva, G V; Sul'ina, Iu S

2015-01-01

In a study there was performed the experimental evaluation of long-term structural--physical changes of the phase of associated water in drinking water treated in hypomagnetic conditions according to the the technology providing the retention of of ortho/para isomers of water in the presence of a catalyst--triplet oxygen. According to the results of measurements ofparameters of nano-associates formed in the water there was found a series ofconsistencies, allowing to determine the mechanisms of the impact of hypomagnetic treatment on the catalytic properties ofwater and long-term stability of its activated state, that provides the long-term maintenance of high biological activity of drinking water. In particular, under hypomagnetic conditions of the treatment there is formed denser packing of amorphous ice--VI in the composition of associates peroxide, serving as a kind of "reservoir" of atmospheric gases. In such a "reservoir" there realized higher pressure, compared with normal geophysical conditions, that stimulates the gas-phase reactions with the formation of dimers and trimers of oxygen existing in the 2-electron--active configurations with binding energies of 0.3 eVand ~0.2 eV providing phase modulation, resulting in condensation of environment additional electrons on paramagnetic oxygen, which provides the long-term maintenance of the electron--donor ability of water and electrically non-equilibrium state.

Fabrication of amorphous IGZO thin film transistor using self-aligned imprint lithography with a sacrificial layer

NASA Astrophysics Data System (ADS)

Kim, Sung Jin; Kim, Hyung Tae; Choi, Jong Hoon; Chung, Ho Kyoon; Cho, Sung Min

2018-04-01

An amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistor (TFT) was fabricated by a self-aligned imprint lithography (SAIL) method with a sacrificial photoresist layer. The SAIL is a top-down method to fabricate a TFT using a three-dimensional multilayer etch mask having all pattern information for the TFT. The sacrificial layer was applied in the SAIL process for the purpose of removing the resin residues that were inevitably left when the etch mask was thinned by plasma etching. This work demonstrated that the a-IGZO TFT could be fabricated by the SAIL process with the sacrificial layer. Specifically, the simple fabrication process utilized in this study can be utilized for the TFT with a plasma-sensitive semiconductor such as the a-IGZO and further extended for the roll-to-roll TFT fabrication.

Fabrication of 3D SiO x structures using patterned PMMA sacrificial layer

NASA Astrophysics Data System (ADS)

Li, Zhiqin; Xiang, Quan; Zheng, Mengjie; Bi, Kaixi; Chen, Yiqin; Chen, Keqiu; Duan, Huigao

2018-02-01

Three-dimensional (3D) nanofabrication based on electron-beam lithography (EBL) has drawn wide attention for various applications with its high patterning resolution and design flexibility. In this work, we present a bilayer EBL process to obtain 3D freestanding SiO x structures via the release of the bottom sacrificial layer. This new kind of bilayer process enables us to define various 3D freestanding SiO x structures with high resolution and low edge roughness. As a proof of concept for applications, metal-coated freestanding SiO x microplates with an underlying air gap were fabricated to form asymmetric Fabry-Perot resonators, which can be utilized for colorimetric refractive index sensing and thus also have application potential for biochemical detection, anti-counterfeiting and smart active nano-optical devices.

Donor states in inverse opals

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

Mahan, G. D.

We calculate the binding energy of an electron bound to a donor in a semiconductor inverse opal. Inverse opals have two kinds of cavities, which we call octahedral and tetrahedral, according to their group symmetry. We put the donor in the center of each of these two cavities and obtain the binding energy. The binding energies become very large when the inverse opal is made from templates with small spheres. For spheres less than 50 nm in diameter, the donor binding can increase to several times its unconfined value. Then electrons become tightly bound to the donor and are unlikelymore » to be thermally activated to the semiconductor conduction band. This conclusion suggests that inverse opals will be poor conductors.« less

Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates

DOEpatents

Melechko, Anatoli V [Oak Ridge, TN; McKnight, Timothy E [Greenback, TN; Guillorn, Michael A [Ithaca, NY; Ilic, Bojan [Ithaca, NY; Merkulov, Vladimir I [Knoxville, TX; Doktycz, Mitchel J [Knoxville, TN; Lowndes, Douglas H [Knoxville, TN; Simpson, Michael L [Knoxville, TN

2012-03-27

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoconduit material coupled to a surface of the substrate. The substrate defines an aperture and the nanoconduit material defines a nanoconduit that is i) contiguous with the aperture and ii) aligned substantially non-parallel to a plane defined by the surface of the substrate.

Influence of Bicarbonate, Sulfate, and Electron Donors on Biological reduction of Uranium and Microbial Community Composition

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

Luo, Wensui; Zhou, Jizhong; Wu, Weimin

2007-01-01

A microcosm study was performed to investigate the effect of ethanol and acetate on uranium(VI) biological reduction and microbial community changes under various geochemical conditions. Each microcosm contained an uranium-contaminated sediment (up to 2.8 g U/kg) suspended in buffer with bicarbonate at concentrations of either 1 mM or 40 mM and sulfate at either 1.1 or 3.2 mM. Ethanol or acetate was used as an electron donor. Results indicate that ethanol yielded in significantly higher U(VI) reduction rates than acetate. A low bicarbonate concentration (1 mM) was favored for U(VI) bioreduction to occur in sediments, but high concentrations of bicarbonatemore » (40 mM) and sulfate (3.2 mM) decreased the reduction rates of U(VI). Microbial communities were dominated by species from the Geothrix genus and Proteobacteria phylum in all microcosms. However, species in the Geobacteraceae family capable of reducing U(VI) were significantly enriched by ethanol and acetate in low bicarbonate buffer. Ethanol increased the population of unclassified Desulfuromonales, while acetate increased the population of Desulfovibrio. Additionally, species in the Geobacteraceae family were not enriched in high bicarbonate buffer, but the Geothrix and the unclassified Betaproteobacteria species were enriched. This study concludes that ethanol could be a better electron donor than acetate for reducing U(VI) under given experimental conditions, and electron donor and geoundwater geochemistry alter microbial communities responsible for U(VI) reduction.« less

U(VI) bioreduction with emulsified vegetable oil as the electron donor--model application to a field test.

PubMed

Tang, Guoping; Watson, David B; Wu, Wei-Min; Schadt, Christopher W; Parker, Jack C; Brooks, Scott C

2013-04-02

We amended a shallow fast-flowing uranium (U) contaminated aquifer with emulsified vegetable oil (EVO) and subsequently monitored the biogeochemical responses for over a year. Using a biogeochemical model developed in a companion article (Tang et al., Environ. Sci. Technol.2013, doi: 10.1021/es304641b) based on microcosm tests, we simulated geochemical and microbial dynamics in the field test during and after the 2-h EVO injection. When the lab-determined parameters were applied in the field-scale simulation, the estimated rate coefficient for EVO hydrolysis in the field was about 1 order of magnitude greater than that in the microcosms. Model results suggested that precipitation of long-chain fatty acids, produced from EVO hydrolysis, with Ca in the aquifer created a secondary long-term electron donor source. The model predicted substantial accumulation of denitrifying and sulfate-reducing bacteria, and U(IV) precipitates. The accumulation was greatest near the injection wells and along the lateral boundaries of the treatment zone where electron donors mixed with electron acceptors in the groundwater. While electron acceptors such as sulfate were generally considered to compete with U(VI) for electrons, this work highlighted their role in providing electron acceptors for microorganisms to degrade complex substrates thereby enhancing U(VI) reduction and immobilization.

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.

Synthesis and room temperature photo-induced electron transfer in biologically active bis(terpyridine)ruthenium(II)-cytochrome c bioconjugates and the effect of solvents on the bioconjugation of cytochrome c.

PubMed

Peterson, Joshua R; Smith, Trevor A; Thordarson, Pall

2010-01-07

Photo-active bis(terpyridine)ruthenium(ii) chromophores were synthesised and attached to the redox enzyme iso-1 cytochrome c in a mixed solvent system to form photo-induced bioconjugates in greater than 40% yield after purification. The effects of up to 20% (v/v) of acetonitrile, tetrahydrofuran, dimethylformamide, or dimethyl sulfoxide at 4, 25 and 35 degrees C on the stability and biological activity of cytochrome c and its reactivity towards the model compound 4,4'-dithiodipyridine (DTDP) was measured. The second-order rate constant for the DTDP reaction was found to range between k = 2.5-4.3 M(-1) s(-1) for reactions with 5% organic solvent added compared to k = 5.6 M(-1) s(-1) in pure water at 25 degrees C. Use of 20% solvent generally results in significant protein oxidation, and 20% acetonitrile and tetrahydrofuran in particular result in significant protein dimerization, which competes with the bioconjugation reaction. Cyclic voltammetry studies indicated that the rate of electron transfer to the heme in solution was reduced in the bis(terpyridine)ruthenium(ii) cytochrome c bioconjugates compared to unmodified cytochrome c. Steady-state fluorescence studies on these bioconjugates showed that energy or electron transfer is taking place between the bis(terpyridine)ruthenium(ii) chromophores and cytochrome c. The bis(terpyridine)ruthenium(ii) cytochrome c bioconjugates demonstrate room temperature photo-activated electron transfer from the bis(terpyridine)ruthenium(ii) donor to the protein acceptor. Two sacrificial donors were used; in 50% glycerol, the bioconjugates were reduced in about 15 min while in 20 mM EDTA the bioconjugates were fully reduced in less than 5 min upon irradiation with a xenon lamp source. Under these conditions, the reduction of the non-covalent mixture of cytochrome c and bis(terpyridine)ruthenium(ii) mixtures took over 30 min. Control experiments showed that the photo-induced reduction of cytochrome c only occurs in the absence of

Donors' blood group declaration before donation can be used as a tool for electronic crossmatching.

PubMed

Arslan, O

2005-12-01

Electronic crossmatching (E-XM) is used to detect ABO incompatibility. In developing countries, as many of the donations are from first-time donors, it is difficult to guarantee the accuracy of the ABO/Rh label on these units to use them for E-XM. This problem was overcome with a new software 'hemosoft', using donors' blood group declaration before donation as a tool for E-XM. During registration, donors either declare their blood group or give no comment. For, ABO/Rh grouping, either two results from different donations or only one in concordant with the declaration before donation is needed. If there is a conflict, second typing is performed from the unit segment. If donors give no declaration, two different technicians perform typing, one from the sample tube and the other from the unit segment. Of 18,618 donations performed, 640 (3%) were repeated and the rest were first-time donations. In 16,327, typing was performed once, as the blood group declaration and the typing results were identical. In 2407, grouping was performed twice, as donors gave no declaration or conflicts between declaration and typing results were found. No labelling or wrong unit-release errors were detected in units donated, typed and labelled in our centre. In 26,402 donations, 16,314 (61.8%) E-XMs were performed. No major haemolytic transfusion reaction was recorded. Donors' ABO/Rh declaration before donation can be used as a tool for E-XM, instead of the requirement for serological confirmation or a second donation to guarantee grouping.

Fine-tuning of electronic properties in donor-acceptor conjugated polymers based on oligothiophenes

NASA Astrophysics Data System (ADS)

Imae, Ichiro; Sagawa, Hitoshi; Harima, Yutaka

2018-03-01

A novel series of donor-acceptor conjugated polymers having oligothiophenes with well-defined structures were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. It was found that the absorption bands of polymers were red-shifted with increasing number of ethylenedioxy groups added to each oligothiophene unit and that their band edges reached over 1000 nm. The systematical fine-tuning of the electronic properties was achieved using the chemical structures of oligothiophene units. Photovoltaic cells based on polymer/(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) exhibited power conversion efficiencies in the range from 0.004 to 1.10%, reflecting the electronic properties of the polymers.

The separation distance distribution in electron-donor-acceptor systems and the wavelength dependence of free ion yields

NASA Astrophysics Data System (ADS)

Zhou, Jinwei; Findley, Bret R.; Braun, Charles L.; Sutin, Norman

2001-06-01

We recently reported that free radical ion quantum yields for electron-donor-acceptor (EDA) systems of alkylbenzenes-tetracyanoethylene (TCNE) exhibit a remarkable wavelength dependence in dichloromethane, a medium polarity solvent. We proposed that weak absorption by long-distance, unassociated or "random" D⋯A pairs is mainly responsible for the free radical ion yield. Here a model for the wavelength dependence of the free ion yield is developed for four systems in which differing degrees of EDA complex formation are present: 1,3,5-tri-tert-butylbenzene-TCNE in which only random pairs exist due to the bulky groups on the electron donor, and toluene—TCNE, 1,3,5-triethylbenzene-TCNE and 1,3,5-trimethylbenzene-TCNE. Mulliken-Hush theory is used to determine the excitation distance distribution of unassociated, random pairs at different wavelengths. For each absorption distribution, free radical ion yields at different wavelengths are then calculated using Onsager's result for the ion separation probability. Encouraging agreement between the calculated yields and our experimental results is obtained. As far as we are aware, this is the first time that photoexcitation of unassociated donor/acceptor pairs has been invoked as the source of separated radical ion pairs.

Donor-acceptor-donor thienyl/bithienyl-benzothiadiazole/quinoxaline model oligomers: experimental and theoretical studies.

PubMed

Pina, João; de Melo, J Seixas; Breusov, D; Scherf, Ullrich

2013-09-28

A comprehensive spectral and photophysical investigation of four donor-acceptor-donor (DAD) oligomers consisting of electron-deficient 2,1,3-benzothiadiazole or quinoxaline moieties linked to electron-rich thienyl or bithienyl units has been undertaken. Additionally, a bis(dithienyl) substituted naphthalene was also investigated. The D-A-D nature of these oligomers resulted in the presence of an intramolecular charge transfer (ICT) state, which was further substantiated by solvatochromism studies (analysis with the Lippert-Mataga formalism). Hereby, significant differences have been obtained for the fluorescence quantum yields of the oligomers in the non-polar solvent methylcyclohexane vs. the polar ethanol. The study was further complemented with the determination of the optimized ground-state molecular geometries for the oligomers together with the prediction of the lowest vertical one-electron excitation energy and the relevant molecular orbital contours using DFT calculations. The electronic transitions show a clear HOMO to LUMO charge-transfer character. In contrast to the thiophene oligomers (the oligothiophenes with n = 1-7), where the intersystem crossing (ISC) yield decreases with n, the studied DAD oligomers were found to show an increase in the ISC efficiency with the number of (donor) thienyl units.

Density functional study of the electronic structure of dye-functionalized fullerenes and their model donor-acceptor complexes containing P3HT

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

Baruah, Tunna; Garnica, Amanda; Paggen, Marina

2016-04-14

We study the electronic structure of C{sub 60} fullerenes functionalized with a thiophene-diketo-pyrrolopyrrole-thiophene based chromophore using density functional theory combined with large polarized basis sets. As the attached chromophore has electron donor character, the functionalization of the fullerene leads to a donor-acceptor (DA) system. We examine in detail the effect of the linker and the addition site on the electronic structure of the functionalized fullerenes. We further study the electronic structure of these DA complexes with a focus on the charge transfer excitations. Finally, we examine the interface of the functionalized fullerenes with the widely used poly(3-hexylthiophene-2,5-diyl) (P3HT) donor. Ourmore » results show that all functionalized fullerenes with an exception of the C{sub 60}-pyrrolidine [6,6], where the pyrrolidine is attached at a [6,6] site, have larger electron affinities relative to the pristine C{sub 60} fullerene. We also estimate the quasi-particle gap, lowest charge transfer excitation energy, and the exciton binding energies of the functionalized fullerene-P3MT model systems. Results show that the exciton binding energies in these model complexes are slightly smaller compared to a similarly prepared phenyl-C{sub 61}-butyric acid methyl ester (PCBM)-P3MT complex.« less

Tuning the Rectification Ratio by Changing the Electronic Nature (Open-Shell and Closed-Shell) in Donor-Acceptor Self-Assembled Monolayers.

PubMed

Souto, Manuel; Yuan, Li; Morales, Dayana C; Jiang, Li; Ratera, Imma; Nijhuis, Christian A; Veciana, Jaume

2017-03-29

This Communication describes the mechanism of charge transport across self-assembled monolayers (SAMs) of two donor-acceptor systems consisting of a polychlorotriphenylmethyl (PTM) electron-acceptor moiety linked to an electron-donor ferrocene (Fc) unit supported by ultraflat template-stripped Au and contacted by a eutectic alloy of gallium and indium top contacts. The electronic and supramolecular structures of these SAMs were well characterized. The PTM unit can be switched between the nonradical and radical forms, which influences the rectification behavior of the junction. Junctions with nonradical units rectify currents via the highest occupied molecular orbital (HOMO) with a rectification ratio R = 99, but junctions with radical units have a new accessible state, a single-unoccupied molecular orbital (SUMO), which turns rectification off and drops R to 6.

Sacrificial bonds and hidden length in biomaterials -- a kinetic description of strength and toughness in bone

NASA Astrophysics Data System (ADS)

Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

2013-03-01

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism of energy dissipation. One example of occurrence of sacrificial bonds and hidden length is in the polymeric glue connection between collagen fibrils in animal bone. In this talk, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the revelation of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation, at the mean-field level, allowing for the number of bonds and hidden lengths to take up non-integer values between successive, discrete bond-breakage events. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

Nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates

DOEpatents

Melechko, Anatoli V [Oak Ridge, TN; McKnight, Timothy E. , Guillorn, Michael A.; Ilic, Bojan [Ithaca, NY; Merkulov, Vladimir I [Knoxville, TN; Doktycz, Mitchel J [Knoxville, TN; Lowndes, Douglas H [Knoxville, TN; Simpson, Michael L [Knoxville, TN

2011-05-17

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. A method includes depositing a catalyst particle on a surface of a substrate to define a deterministically located position; growing an aligned elongated nanostructure on the substrate, an end of the aligned elongated nanostructure coupled to the substrate at the deterministically located position; coating the aligned elongated nanostructure with a conduit material; removing a portion of the conduit material to expose the catalyst particle; removing the catalyst particle; and removing the elongated nanostructure to define a nanoconduit.

Application of acetate, lactate, and fumarate as electron donors in microbial fuel cell

NASA Astrophysics Data System (ADS)

Vasyliv, Oresta M.; Bilyy, Oleksandr I.; Ferensovych, Yaroslav P.; Hnatush, Svitlana O.

2013-09-01

Microbial fuel cells (MFCs) are devices that use bacteria as the catalysts to oxidize organic and inorganic matter and generate current. Up to now, several classes of extracellular electron transfer mechanisms have been elucidated for various microorganisms. Shewanellaceae and Geobacteraceae families include the most of model exoelectrogenic microorganisms. Desulfuromonas acetoxidans bacterium inhabits aquatic sedimental sulfur-containing environments and is philogenetically close to representatives of Geobacteraceae family. Two chamber microbial fuel cell (0.3 l volume) was constructed with application of D. acetoxidans IMV B-7384 as anode biocatalyst. Acetic, lactic and fumaric acids were separately applied as organic electron donors for bacterial growth in constructed MFC. Bacterial cultivation in MFC was held during twenty days. Lactate oxidation caused electric power production with the highest value up to 0.071 mW on 64 hour of D. acetoxidans IMV B-7384 growth. Addition of acetic and fumaric acids into bacterial growth medium caused maximal power production up to 0.075 and 0.074 mW respectively on the 40 hour of their growth. Increasing of incubation time up to twentieth day caused decrease of generated electric power till 0.018 mW, 0.042 mW and 0.047 mW under usage of lactic, acetic and fumaric acids respectively by investigated bacteria. Power generation by D. acetoxidans IMV B-7384 was more stabile and durable under application of acetic and fumaric acids as electron donors in constructed MFC, than under addition of lactic acid in the same concentration into the growth medium.

Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications

NASA Astrophysics Data System (ADS)

Wei, Yang; Torah, Russel; Yang, Kai; Beeby, Steve; Tudor, John

2013-07-01

Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications.

Modification of indole by electron-rich atoms and their application in novel electron donor materials

NASA Astrophysics Data System (ADS)

Zhang, Maolin; Qin, Guangjiong; Liu, Jialei; Zhen, Zhen; Fedorchuk, A. A.; Lakshminarayana, G.; Albassam, A. A.; El-Naggar, A. M.; Ozga, Katarzyna; Kityk, I. V.

2017-08-01

Novel nonlinear optical (NLO) chromophore based on 6-(pyrrolidin-1-yl)-1H-indole as the electron donor group was designed and synthesized. The molecular structure of this chromophore was characterized by 1H NMR spectra, 13C NMR spectra, and MS spectra. The delocalized energy level was estimated by UV-Vis. spectra. The thermal property was studied by thermogravimetric analysis (TGA). The poled films containing chromophores ZML-1 with a loading density of 10 wt% in amorphous polycarbonate (APC) afford an average electro-optic (EO) coefficient (r33) of 19 pm/V at 1310 nm. Compared to the reported aniline-based chromophore (r33 = 12 pm/V) analogues, chromophore ZML-1 exhibits enhanced electro-optical activity.

Effective treatment of alkaline Cr(VI) contaminated leachate using a novel Pd-bionanocatalyst: Impact of electron donor and aqueous geochemistry

PubMed Central

Watts, Mathew P.; Coker, Victoria S.; Parry, Stephen A.; Thomas, Russell A.P.; Kalin, Robert; Lloyd, Jonathan R.

2015-01-01

Palladium catalysts offer the potential for the effective treatment of a variety of priority reducible pollutants in natural waters. In this study, microbially synthesized magnetite nanoparticles were functionalized with Pd(0), creating a highly reactive, magnetically recoverable, nano-scale catalyst (Pd-BnM). This was then investigated for the treatment of model Cr(VI) contaminated solutions at a range of pH values, and also alkaline Cr(VI) contaminated leachates from chromite ore processing residue (COPR); a contaminant issue of global concern. The sample of COPR used in this study was obtained from a site in Glasgow, UK, where extensive Cr(VI) contamination has been reported. In initial experiments Pd-BnM was supplied with H2 gas or formate as electron donors, and Cr(VI) removal from model synthetic solutions was quantified at various pH values (2–12). Effective removal was noted at neutral to environmentally relevant alkaline (pH 12) pH values, while the use of formate as an electron donor resulted in loss of performance under acidic conditions (pH 2). Reaction kinetics were then assessed with increasing Pd-BnM loading in both model pH 12 Cr(VI) solutions and the COPR leachate. When formate was used as the electron donor for Pd-BnM, to treat COPR leachate, there was significant inhibition of Cr(VI) removal. In contrast, a promotion of reaction rate, was observed when H2 was employed. Upon sustained reaction with model Cr(VI) solutions, in the presence of excess electron donor (formate or H2), appreciable quantities of Cr(VI) were removed before eventual inactivation of the catalyst. Faster onset of inactivation was reported in the COPR leachates, removing 4% and 64% of Cr(VI) observed from model Cr(VI) solutions, when formate and H2 were used as electron donors, respectively. XAS, TEM-EDX and XPS analysis of the catalysts that had been inactivated in the model solution, showed that the surface had an extensive covering of reduced Cr(III), most likely as a Cr

A facile alternative technique for large-area graphene transfer via sacrificial polymer

DOE PAGES

Auchter, Eric; Marquez, Justin; Yarbro, Stephen L.; ...

2017-12-07

A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal) is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated themore » effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.« less

A facile alternative technique for large-area graphene transfer via sacrificial polymer

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

Auchter, Eric; Marquez, Justin; Yarbro, Stephen L.

A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal) is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated themore » effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.« less

Self-assembly properties of semiconducting donor-acceptor-donor bithienyl derivatives of tetrazine and thiadiazole-effect of the electron accepting central ring.

PubMed

Zapala, Joanna; Knor, Marek; Jaroch, Tomasz; Maranda-Niedbala, Agnieszka; Kurach, Ewa; Kotwica, Kamil; Nowakowski, Robert; Djurado, David; Pecaut, Jacques; Zagorska, Malgorzata; Pron, Adam

2013-11-26

Scanning tunneling microscopy was used to study the effect of the electron-accepting unit and the alkyl substituent's position on the type and extent of 2D supramolecular organization of penta-ring donor-acceptor-donor (DAD) semiconductors, consisting of either tetrazine or thiadiazole central acceptor ring symmetrically attached to two bithienyl groups. Microscopic observations of monomolecular layers on HOPG of four alkyl derivatives of the studied adsorbates indicate significant differences in their 2D organizations. Ordered monolayers of thiadiazole derivatives are relatively loose and, independent of the position of alkyl substituents, characterized by large intermolecular separation of acceptor units in the adjacent molecules located in the face-to-face configuration. The 2D supramolecular architecture in both derivatives of thiadiazole is very sensitive to the alkyl substituent's position. Significantly different behavior is observed for derivatives of tetrazine (which is a stronger electron acceptor). Stronger intermolecular DA interactions in these adsorbates generate an intermolecular shift in the monolayer, which is a dominant factor determining the 2D structural organization. As a consequence of this molecular arrangement, tetrazine groups (A segments) face thiophene rings (D segments) of the neighboring molecules. Monolayers of tetrazine derivatives are therefore much more densely packed and characterized by similar π-stacking of molecules independently of the position of alkyl substituents. Moreover, a comparative study of 3D supramolecular organization, deduced from the X-ray diffraction patterns, is also presented clearly confirming the polymorphism of the studied adsorbates.

Effect of Electron Donor and Solution Chemistry on Products of Dissimilatory Reduction of Technetium by Shewanella putrefaciens

PubMed Central

Wildung, R. E.; Gorby, Y. A.; Krupka, K. M.; Hess, N. J.; Li, S. W.; Plymale, A. E.; McKinley, J. P.; Fredrickson, J. K.

2000-01-01

To help provide a fundamental basis for use of microbial dissimilatory reduction processes in separating or immobilizing 99Tc in waste or groundwaters, the effects of electron donor and the presence of the bicarbonate ion on the rate and extent of pertechnetate ion [Tc(VII)O4−] enzymatic reduction by the subsurface metal-reducing bacterium Shewanella putrefaciens CN32 were determined, and the forms of aqueous and solid-phase reduction products were evaluated through a combination of high-resolution transmission electron microscopy, X-ray absorption spectroscopy, and thermodynamic calculations. When H2 served as the electron donor, dissolved Tc(VII) was rapidly reduced to amorphous Tc(IV) hydrous oxide, which was largely associated with the cell in unbuffered 0.85% NaCl and with extracellular particulates (0.2 to 0.001 μm) in bicarbonate buffer. Cell-associated Tc was present principally in the periplasm and outside the outer membrane. The reduction rate was much lower when lactate was the electron donor, with extracellular Tc(IV) hydrous oxide the dominant solid-phase reduction product, but in bicarbonate systems much less Tc(IV) was associated directly with the cell and solid-phase Tc(IV) carbonate may have been present. In the presence of carbonate, soluble (<0.001 μm) electronegative, Tc(IV) carbonate complexes were also formed that exceeded Tc(VII)O4− in electrophoretic mobility. Thermodynamic calculations indicate that the dominant reduced Tc species identified in the experiments would be stable over a range of Eh and pH conditions typical of natural waters. Thus, carbonate complexes may represent an important pathway for Tc transport in anaerobic subsurface environments, where it has generally been assumed that Tc mobility is controlled by low-solubility Tc(IV) hydrous oxide and adsorptive, aqueous Tc(IV) hydrolysis products. PMID:10831424

Method for integrating microelectromechanical devices with electronic circuitry

DOEpatents

Barron, Carole C.; Fleming, James G.; Montague, Stephen

1999-01-01

A method is disclosed for integrating one or more microelectromechanical (MEM) devices with electronic circuitry on a common substrate. The MEM device can be fabricated within a substrate cavity and encapsulated with a sacrificial material. This allows the MEM device to be annealed and the substrate planarized prior to forming electronic circuitry on the substrate using a series of standard processing steps. After fabrication of the electronic circuitry, the electronic circuitry can be protected by a two-ply protection layer of titanium nitride (TiN) and tungsten (W) during an etch release process whereby the MEM device is released for operation by etching away a portion of a sacrificial material (e.g. silicon dioxide or a silicate glass) that encapsulates the MEM device. The etch release process is preferably performed using a mixture of hydrofluoric acid (HF) and hydrochloric acid (HCI) which reduces the time for releasing the MEM device compared to use of a buffered oxide etchant. After release of the MEM device, the TiN:W protection layer can be removed with a peroxide-based etchant without damaging the electronic circuitry.

Humin as an electron donor for enhancement of multiple microbial reduction reactions with different redox potentials in a consortium.

PubMed

Zhang, Dongdong; Zhang, Chunfang; Xiao, Zhixing; Suzuki, Daisuke; Katayama, Arata

2015-02-01

A solid-phase humin, acting as an electron donor, was able to enhance multiple reductive biotransformations, including dechlorination of pentachlorophenol (PCP), dissimilatory reduction of amorphous Fe (III) oxide (FeOOH), and reduction of nitrate, in a consortium. Humin that was chemically reduced by NaBH4 served as an electron donor for these microbial reducing reactions, with electron donating capacities of 0.013 mmol e(-)/g for PCP dechlorination, 0.15 mmol e(-)/g for iron reduction, and 0.30 mmol e(-)/g for nitrate reduction. Two pairs of oxidation and reduction peaks within the humin were detected by cyclic voltammetry analysis. 16S rRNA gene sequencing-based microbial community analysis of the consortium incubated with different terminal electron acceptors, suggested that Dehalobacter sp., Bacteroides sp., and Sulfurospirillum sp. were involved in the PCP dechlorination, dissimilatory iron reduction, and nitrate reduction, respectively. These findings suggested that humin functioned as a versatile redox mediator, donating electrons for multiple respiration reactions with different redox potentials. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

A simplified methylcoenzyme M methylreductase assay with artificial electron donors and different preparations of component C from Methanobacterium thermoautotrophicum delta H.

PubMed Central

Hartzell, P L; Escalante-Semerena, J C; Bobik, T A; Wolfe, R S

1988-01-01

Different preparations of the methylreductase were tested in a simplified methylcoenzyme M methylreductase assay with artificial electron donors under a nitrogen atmosphere. ATP and Mg2+ stimulated the reaction. Tris(2,2'-bipyridine)ruthenium (II), chromous chloride, chromous acetate, titanium III citrate, 2,8-diaminoacridine, formamidinesulfinic acid, cob(I)alamin (B12s), and dithiothreitol were tested as electron donors; the most effective donor was titanium III citrate. Methylreductase (component C) was prepared by 80% ammonium sulfate precipitation, 70% ammonium sulfate precipitation, phenyl-Sepharose chromatography, Mono Q column chromatography, DEAE-cellulose column chromatography, or tetrahydromethanopterin affinity column chromatography. Methylreductase preparations which were able to catalyze methanogenesis in the simplified reaction mixture contained contaminating proteins. Homogeneous component C obtained from a tetrahydromethanopterin affinity column was not active in the simplified assay but was active in a methylreductase assay that contained additional protein components. Images PMID:3372480

Modeling ultrafast exciton migration within the electron donor domains of bulk heterojunction organic photovoltaics

DOE PAGES

Bednarz, Mateusz; Lapin, Joel; McGillicuddy, Ryan; ...

2017-02-21

Recent experimental studies revealed that charge carriers harvested by bulk heterojunction organic photovoltaics can be collected on ultrafast time scales. To investigate ultrafast exciton mobility, we construct simple, nonatomistic models of a common polymeric electron donor material. We first explore the relationship between the magnitude of energetic noise in the model Hamiltonian and the spatial extent of resulting eigenstates. We then employ a quantum master equation approach to simulate migration of chromophore-localized initial excited states. Excitons initially localized on a single chromophore at the center of the model delocalize down polymer chains and across pi-stacked chromophores through a coherent, wavelikemore » mechanism during the first few tens of femtoseconds. We explore the dependence of this coherent delocalization on coupling strength and on the magnitude of energetic noise. At longer times we observe continued migration toward a uniform population distribution that proceeds through an incoherent, diffusive mechanism. A series of simulations modeling exciton harvesting in domains of varying size demonstrates that smaller domains enhance ultrafast exciton harvesting yield. Finally, our nonatomistic model falls short of quantitative accuracy but demonstrates that excitons are mobile within electron donor domains on ultrafast time scales and that coherent exciton transport can enhance ultrafast exciton harvesting.« less

Modeling ultrafast exciton migration within the electron donor domains of bulk heterojunction organic photovoltaics

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

Bednarz, Mateusz; Lapin, Joel; McGillicuddy, Ryan

Recent experimental studies revealed that charge carriers harvested by bulk heterojunction organic photovoltaics can be collected on ultrafast time scales. To investigate ultrafast exciton mobility, we construct simple, nonatomistic models of a common polymeric electron donor material. We first explore the relationship between the magnitude of energetic noise in the model Hamiltonian and the spatial extent of resulting eigenstates. We then employ a quantum master equation approach to simulate migration of chromophore-localized initial excited states. Excitons initially localized on a single chromophore at the center of the model delocalize down polymer chains and across pi-stacked chromophores through a coherent, wavelikemore » mechanism during the first few tens of femtoseconds. We explore the dependence of this coherent delocalization on coupling strength and on the magnitude of energetic noise. At longer times we observe continued migration toward a uniform population distribution that proceeds through an incoherent, diffusive mechanism. A series of simulations modeling exciton harvesting in domains of varying size demonstrates that smaller domains enhance ultrafast exciton harvesting yield. Finally, our nonatomistic model falls short of quantitative accuracy but demonstrates that excitons are mobile within electron donor domains on ultrafast time scales and that coherent exciton transport can enhance ultrafast exciton harvesting.« less

Stabilizing contact resistance of isotropically conductive adhesives on various metal surfaces by incorporating sacrificial anode materials

NASA Astrophysics Data System (ADS)

Moon, Kyoung-Sik; Liong, Silvia; Li, Haiying; Wong, C. P.

2004-11-01

The contact resistance stability of isotropically conductive adhesives (ICAs) on non-noble metal surfaces under the 85°C/85% relative humidity (RH) aging test was investigated. Previously, we demonstrated that galvanic corrosion has been shown as the main mechanism of the unstable contact resistance of ICAs on non-noble metal surfaces. A sacrificial anode was introduced into the ICA joint for cathodic protection. Zinc, chromium, and magnesium were employed in the ICA formulations as sacrificial anode materials that have much lower electrode-potential values than the metal pad surface, such as tin or tin-based alloys. The effect of particle sizes and loading levels of sacrificial anode materials were studied. Chromium was not as effective in suppressing corrosion as magnesium or zinc because of its strong tendency to self-passivate. The corrosion potential of ICAs was reduced by half with the addition of zinc and magnesium into the ICA formulation. The addition of zinc and magnesium was very effective in controlling galvanic corrosion that takes place in the ICA joints, resulting in stabilized contact resistance of ICAs on Sn, SnPb, and SnAgCu surfaces during the 85°C/85% RH aging test.

Sacrificial bonds in stacked-cup carbon nanofibers: biomimetic toughening mechanisms for composite systems.

PubMed

Palmeri, Marc J; Putz, Karl W; Brinson, L Catherine

2010-07-27

Many natural composites, such as nacre or bone, achieve exceptional toughening enhancements through the rupture of noncovalent secondary bonds between chain segments in the organic phase. This "sacrificial bond" rupture dissipates enormous amounts of energy and reveals significant hidden lengths due to unraveling of the highly coiled macromolecules, leaving the structural integrity of their covalent backbones intact to large extensions. In this work, we present the first evidence of similar sacrificial bond mechanisms in the inorganic phase of composites using inexpensive stacked-cup carbon nanofibers (CNF), which are composed of helically coiled graphene sheets with graphitic spacing between adjacent layers. These CNFs are dispersed in a series of high-performance epoxy systems containing trifunctional and tetrafunctional resins, which are traditionally difficult to toughen in light of their highly cross-linked networks. Nonetheless, the addition of only 0.68 wt % CNF yields toughness enhancements of 43-112% for the various blends. Analysis of the relevant toughening mechanisms reveals two heretofore unseen mechanisms using sacrificial bonds that complement the observed crack deflection, rupture, and debonding/pullout that are common to many composite systems. First, embedded nanofibers can splay discretely between adjacent graphitic layers in the side walls; second, crack-bridging nanofibers can unravel continuously. Both of these mechanisms entail the dissipation of the pi-pi interactions between layers in the side walls without compromising the structural integrity of the graphene sheets. Moreover, increases in electrical conductivity of approximately 7-10 orders of magnitude were found, highlighting the multifunctionality of CNFs as reinforcements for the design of tough, inexpensive nanocomposites with improved electrical properties.

Impact of Temperature and Non-Gaussian Statistics on Electron Transfer in Donor-Bridge-Acceptor Molecules.

PubMed

Waskasi, Morteza M; Newton, Marshall D; Matyushov, Dmitry V

2017-03-30

A combination of experimental data and theoretical analysis provides evidence of a bell-shaped kinetics of electron transfer in the Arrhenius coordinates ln k vs 1/T. This kinetic law is a temperature analogue of the familiar Marcus bell-shaped dependence based on ln k vs the reaction free energy. These results were obtained for reactions of intramolecular charge shift between the donor and acceptor separated by a rigid spacer studied experimentally by Miller and co-workers. The non-Arrhenius kinetic law is a direct consequence of the solvent reorganization energy and reaction driving force changing approximately as hyperbolic functions with temperature. The reorganization energy decreases and the driving force increases when temperature is increased. The point of equality between them marks the maximum of the activationless reaction rate. Reaching the consistency between the kinetic and thermodynamic experimental data requires the non-Gaussian statistics of the donor-acceptor energy gap described by the Q-model of electron transfer. The theoretical formalism combines the vibrational envelope of quantum vibronic transitions with the Q-model describing the classical component of the Franck-Condon factor and a microscopic solvation model of the solvent reorganization energy and the reaction free energy.

Spectrophotometric and spectroscopic studies of charge transfer complexes of p-toluidine as an electron donor with picric acid as an electron acceptor in different solvents

NASA Astrophysics Data System (ADS)

Singh, Neeti; Khan, Ishaat M.; Ahmad, Afaq

2010-04-01

The charge transfer complexes of the donor p-toluidine with π-acceptor picric acid have been studied spectrophotometrically in various solvents such as carbon tetrachloride, chloroform, dichloromethane acetone, ethanol, and methanol at room temperature using absorption spectrophotometer. The results indicate that formation of CTC in non-polar solvent is high. The stoichiometry of the complex was found to be 1:1 ratio by straight-line method between donor and acceptor with maximum absorption bands. The data are discussed in terms of formation constant ( KCT), molar extinction coefficient ( ɛCT), standard free energy (Δ Go), oscillator strength ( f), transition dipole moment ( μEN), resonance energy ( RN) and ionization potential ( ID). The results indicate that the formation constant ( KCT) for the complex was shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents that were used.

Coherent coupling between a quantum dot and a donor in silicon

DOE PAGES

Harvey-Collard, Patrick; Jacobson, N. Tobias; Rudolph, Martin; ...

2017-10-18

Individual donors in silicon chips are used as quantum bits with extremely low error rates. However, physical realizations have been limited to one donor because their atomic size causes fabrication challenges. Quantum dot qubits, in contrast, are highly adjustable using electrical gate voltages. This adjustability could be leveraged to deterministically couple donors to quantum dots in arrays of qubits. In this work, we demonstrate the coherent interaction of a 31P donor electron with the electron of a metal-oxide-semiconductor quantum dot. We form a logical qubit encoded in the spin singlet and triplet states of the two-electron system. We show thatmore » the donor nuclear spin drives coherent rotations between the electronic qubit states through the contact hyperfine interaction. This provides every key element for compact two-electron spin qubits requiring only a single dot and no additional magnetic field gradients, as well as a means to interact with the nuclear spin qubit.« less

Structure and electronic properties of Alq3 derivatives with electron acceptor/donor groups at the C4 positions of the quinolate ligands: a theoretical study.

PubMed

Rao, Joshi Laxmikanth; Bhanuprakash, Kotamarthi

2011-12-01

The molecular structures of the ground (S(0)) and first singlet excited (S(1)) states of Alq3 derivatives in which pyrazolyl and 3-methylpyrazolyl groups are substituted at the C4 positions of the 8-hydroxyquinolate ligands as electron acceptors, and piperidinyl and N-methylpiperazinyl groups are substituted at the same positions as electron donors, have been optimized using the B3LYP/6-31G and CIS/6-31G methods, respectively. In order to analyze the electronic transitions in these derivatives, the frontier molecular orbital characteristics were analyzed systematically, and it was found that the highest occupied molecular orbital is localized on the A ligand while the lowest unoccupied molecular orbital is localized on the B ligand in their ground states, similar to what is seen for mer-Alq3. The absorption and emission spectra were evaluated at the TD-PBE0/6-31G level, and it was observed that electron acceptor substitution causes a red-shift in the emission spectra, which is also seen experimentally. The reorganization energies were calculated at the B3LYP/6-31G level and the results show that acceptor/donor substitution has a significant effect on the intrinsic charge mobilities of these derivatives as compared to mer-Alq3.

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.

Comparative surface studies on wet and dry sacrificial thermal oxidation on silicon carbide

NASA Astrophysics Data System (ADS)

Koh, A.; Kestle, A.; Wright, C.; Wilks, S. P.; Mawby, P. A.; Bowen, W. R.

2001-04-01

A comparative study on the effect of wet and dry thermal oxidation on 4H-silicon carbide (SiC) and on sacrificial silicon (Si) thermal oxidation on 4H-SiC surface has been conducted using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The AFM images show the formation of 'nano-islands' of varying density on the SiC surface after the removal of thermal oxide using hydrofluoric (HF) acid etch. These nano-islands are resistant to HF acid and have been previously linked to residual carbon [1-3] resulting from the oxidation process. This paper presents the use of a sacrificial silicon oxidation (SSO) step as a form of surface preparation that gives a reproducible clean SiC surface. XPS results show a slight electrical shift in binding energy between the wet and dry thermal oxidation on the standard SiC surface, while the surface produced by the SSO technique shows a minimal shift.

Biodistance analysis of the Moche sacrificial victims from Huaca de la Luna plaza 3C: Matrix method test of their origins.

PubMed

Sutter, Richard C; Verano, John W

2007-02-01

The purpose of this study is to test two competing models regarding the origins of Early Intermediate Period (AD 200-750) sacrificial victims from the Huacas de Moche site using the matrix correlation method. The first model posits the sacrificial victims represent local elites who lost competitions in ritual battles with one another, while the other model suggests the victims were nonlocal warriors captured during warfare with nearby polities. We estimate biodistances for sacrificial victims from Huaca de la Luna Plaza 3C (AD 300-550) with eight previously reported samples from the north coast of Peru using both the mean measure of divergence (MMD) and Mahalanobis' distance (d2). Hypothetical matrices are developed based upon the assumptions of each of the two competing models regarding the origins of Moche sacrificial victims. When the MMD matrix is compared to the two hypothetical matrices using a partial-Mantel test (Smouse et al.: Syst Zool 35 (1986) 627-632), the ritual combat model (i.e. local origins) has a low and nonsignificant correlation (r = 0.134, P = 0.163), while the nonlocal origins model is highly correlated and significant (r = 0.688, P = 0.001). Comparisons of the d2 results and the two hypothetical matrices also produced low and nonsignificant correlation for the ritual combat model (r = 0.210, P = 0.212), while producing a higher and statistically significant result with the nonlocal origins model (r = 0.676, P = 0.002). We suggest that the Moche sacrificial victims represent nonlocal warriors captured in territorial combat with nearby competing polities. Copyright 2006 Wiley-Liss, Inc.

The effect of zinc (Zn) content to cell potential value and efficiency aluminium sacrificial anode in 0.2 M sulphuric acid environment

NASA Astrophysics Data System (ADS)

Akranata, Ahmad Ridho; Sulistijono, Awali, Jatmoko

2018-04-01

Sacrificial anode is sacirifial component that used to protect steel from corrosion. Generally, the component are made of aluminium and zinc in water environment. Sacrificial anode change the protected metal structure become cathodic with giving current. The advantages of aluminium is corrosion resistance, non toxicity and easy forming. Zinc generally used for coating in steel to prevent steel from corrosion. This research was conducted to analyze the effect of zinc content to the value of cell potential and efficiency aluminium sacrificial anode with sand casting method in 0.2 M sulphuric acid environment. The sacrificial anode fabrication made with alloying aluminium and zinc metals with variation composition of alloy with pure Al, Al-3Zn, Al-6Zn, and Al-9Zn with open die sand casting process. The component installed with ASTM A36 steel. After the research has been done the result showed that addition of zinc content increase the cell potential, protection efficiency, and anode efficiency from steel plate. Cell potential value measurement and weight loss measurement showed that addition of zinc content increase the cell potential value into more positive that can protected the ASTM A36 steel more efficiently that showed in weight loss measurement where the protection efficiency and anodic efficiency of Al-9Zn sacrificial anode is better than protection efficiency and anodic efficiency of pure Al. The highest protection efficiency gotten by Al-9Zn alloy

Outcomes of red blood cell transfusions prescribed in organ donors by the Digital Intern, an electronic decision support algorithm.

PubMed

Connor, Joseph P; Raife, Thomas; Medow, Joshua E

2018-02-01

The Digital Intern (DI) is an electronic decision support tool for the management of organ donors. One algorithm determines the dose, in units of red blood cells to be transfused, based on hematocrit (Hct) thresholds and targets. The effectiveness of the transfusion dose calculated by the DI in terms of achieving the selected Hct target and the duration of the targeted dose is not known. This was a retrospective study to describe the outcomes of transfusions prescribed by the DI. Pre- and posttransfusion Hct levels were compared to define response and all posttransfusion Hct values were plotted to evaluate the duration of the prescribed dose. A total of 120 organ donors were studied and 22 donors had 28 transfusions (six were transfused twice). The transfused donors were a mix of trauma and medical admissions and brain death and cardiac death donors. The transfusion target of 24% Hct was attained in 96% of transfusions. The mean number of units transfused was 1.4 and the mean time from transfusion to procurement was 19.8 hours. There was a decline in Hct over time after transfusion in all but one case with a mean decline of 1.9% Hct over 13 hours. Six donors were transfused twice, likely due to a longer donor time period (41.7 hr vs. 27 hr). The DI provided transfusion dosing that achieved the desired threshold in the majority of organ donors transfused. Ongoing work focuses on application of this technology to transfusions in general patient populations. © 2017 AABB.

From Eshu to Obatala: animals used in sacrificial rituals at Candomblé "terreiros" in Brazil

PubMed Central

Léo Neto, Nivaldo A; Brooks, Sharon E; Alves, Rômulo RN

2009-01-01

Background The practice of sacrifice has occurred in several cultures and religions throughout history and still exists today. Candomblé, a syncretical Afro-Brazilian religion, practices the sacrificial ritual called "Orô" by its adherents. The present work aims to document the use of animal species in these sacrificial practices in the cities of Caruaru (PE) and Campina Grande (PB) in Norteastern Brazil, and to further understand the symbolism of these rituals. Methods Semi-structured and unstructured interviews and informal discussions were held with 11 Candomblé priests and priestesses between the months of August 2007 and June 2008. We attended rituals performed at "terreiros" where animals were sacrificed, in order to obtain photographic material and observe the procedures and techniques adopted. Results A total of 29 animal species were used during sacrificial rituals according to the priests and priestesses. These species were classified in 5 taxanomic groups: Molluscs (n = 1), Amphibians (n = 2), Reptiles (n = 2), Birds (n = 10) and Mammals (n = 14). According to Candomblé beliefs, animals are sacrificed and offered to their deities, known as orishas, for the prosperity of all life. There is a relationship between the colour, sex and behaviour of the animal to be sacrificed, and the orisha to whom the animal is going to be offered. The many myths that form the cosmogony of Candomblé can often explain the symbolism of the rituals observed and the animal species sacrificed. These myths are conveyed to adherants by the priests and priestesses during the ceremonies, and are essential to the continuation of this religion. Conclusion Candomblé is a sacrificial religion that uses animals for its liturgical purposes. The principal reason for sacrifice is to please supernatural deities known as orishas in order to keep life in harmony. This is accomplished through feeding them in a spiritual sense through sacrifice, maintaining a perfect link between men and

Super electron donor-mediated reductive transformation of nitrobenzenes: a novel strategy to synthesize azobenzenes and phenazines.

PubMed

Nozawa-Kumada, Kanako; Abe, Erina; Ito, Shungo; Shigeno, Masanori; Kondo, Yoshinori

2018-05-02

The transformation of nitrobenzenes into azobenzenes by pyridine-derived super electron donor 2 is described. This method provides an efficient synthesis of azobenzenes because of not requiring the use of expensive transition-metals, toxic or flammable reagents, or harsh conditions. Moreover, when using 2-fluoronitrobenzenes as substrates, phenazines were found to be obtained. The process affords a novel synthesis of phenazines.

Spontaneous nano-gap formation in Ag film using NaCl sacrificial layer for Raman enhancement

NASA Astrophysics Data System (ADS)

Min, Kyungchan; Jeon, Wook Jin; Kim, Youngho; Choi, Jae-Young; Yu, Hak Ki

2018-03-01

We report the method of fabrication of nano-gaps (known as hot spots) in Ag thin film using a sodium chloride (NaCl) sacrificial layer for Raman enhancement. The Ag thin film (20-50 nm) on the NaCl sacrificial layer undergoes an interfacial reaction due to the AgCl formed at the interface during water molecule intercalation. The intercalated water molecules can dissolve the NaCl molecules at interfaces and form the ionic state of Na+ and Cl-, promoting the AgCl formation. The Ag atoms can migrate by the driving force of this interfacial reaction, resulting in the formation of nano-size gaps in the film. The surface-enhanced Raman scattering activity of Ag films with nano-size gaps has been investigated using Raman reporter molecules, Rhodamine 6G (R6G).

New Sm(III) complexes as electronic-excitation donors of the Seta-632 squaraine dye

NASA Astrophysics Data System (ADS)

Egorova, A. V.; Leonenko, I. I.; Aleksandrova, D. I.; Skripinets, Yu. V.; Antonovich, V. P.; Obukhova, E. N.; Patsenker, L. D.

2015-07-01

We have found optimal formation conditions of new Sm(III) chelate complexes with derivatives of oxoquinolinecarboxylic acid ( L 1 and L 2) and determined their spectral-luminescent characteristics (the luminescence and luminescence excitation wavelength maxima and the luminescence lifetimes). We have revealed that the Seta-632 squaraine dye (a fluorescent label of proteins and other biological molecules) quenches the luminescence of complexes Sm(III)- L 1 and Sm(III)- L 2. The quenching of chelate complexes is caused by the Förster resonant electronic-excitation energy transfer (FRET) from the donor (Sm(III)- L 1 or Sm(III)- L 2) to the acceptor (Seta-632). In this case, the luminescence intensity of the Seta-632 dye in the presence of Sm(III)- L 1 and Sm(III)- L 2 increases by factors of 64 and 27, respectively. The values of the Förster radii ( R 0(Sm- L1) = 38 Å, R 0(Sm- L2) = 35 Å) and the overlap integrals of the luminescence spectra of the two energy donors with the absorption spectrum of the acceptor ( J Sm- L1 = 1.22 × 1012 M-1 cm-1 nm4 and J Sm- L2 = 1.06 × 1012 M-1 cm-1 nm4), which have been calculated from the luminescence quantum intensity of the donors and from the absorption spectrum of the acceptor and its molar absorption coefficient, have made it possible to characterize the Seta-632 dye as an efficient quencher of the luminescence of Sm(III) ions. We are the first to propose Sm(III)- L 1 and Sm(III)- L 2 chelate complexes as FRET donors.

Vertically aligned carbon nanofibers as sacrificial templates for nanofluidic structures

NASA Astrophysics Data System (ADS)

Melechko, A. V.; McKnight, T. E.; Guillorn, M. A.; Merkulov, V. I.; Ilic, B.; Doktycz, M. J.; Lowndes, D. H.; Simpson, M. L.

2003-02-01

We report a method to fabricate nanoscale pipes ("nanopipes") suitable for fluidic transport. Vertically aligned carbon nanofibers grown by plasma-enhanced chemical vapor deposition are used as sacrificial templates for nanopipes with internal diameters as small as 30 nm and lengths up to several micrometers that are oriented perpendicular to the substrate. This method provides a high level of control over the nanopipe location, number, length, and diameter, permitting them to be deterministically positioned on a substrate and arranged into arrays.

Current oscillations in semi-insulating GaAs associated with field-enhanced capture of electrons by the major deep donor EL2

NASA Technical Reports Server (NTRS)

Kaminska, M.; Parsey, J. M.; Lagowski, J.; Gatos, H. C.

1982-01-01

Current oscillations thermally activated by the release of electrons from deep levels in undoped semiinsulating GaAs were observed for the first time. They were attributed to electric field-enhanced capture of electrons by the dominant deep donor EL2 (antisite AsGa defect). This enhanced capture is due to the configurational energy barrier of EL2, which is readily penetrated by hot electrons.

Isolation of Acetogenic Bacteria That Induce Biocorrosion by Utilizing Metallic Iron as the Sole Electron Donor

PubMed Central

Yumoto, Isao; Kamagata, Yoichi

2014-01-01

Corrosion of iron occurring under anoxic conditions, which is termed microbiologically influenced corrosion (MIC) or biocorrosion, is mostly caused by microbial activities. Microbial activity that enhances corrosion via uptake of electrons from metallic iron [Fe(0)] has been regarded as one of the major causative factors. In addition to sulfate-reducing bacteria and methanogenic archaea in marine environments, acetogenic bacteria in freshwater environments have recently been suggested to cause MIC under anoxic conditions. However, no microorganisms that perform acetogenesis-dependent MIC have been isolated or had their MIC-inducing mechanisms characterized. Here, we enriched and isolated acetogenic bacteria that induce iron corrosion by utilizing Fe(0) as the sole electron donor under freshwater, sulfate-free, and anoxic conditions. The enriched communities produced significantly larger amounts of Fe(II) than the abiotic controls and produced acetate coupled with Fe(0) oxidation prior to CH4 production. Microbial community analysis revealed that Sporomusa sp. and Desulfovibrio sp. dominated in the enrichments. Strain GT1, which is closely related to the acetogen Sporomusa sphaeroides, was eventually isolated from the enrichment. Strain GT1 grew acetogenetically with Fe(0) as the sole electron donor and enhanced iron corrosion, which is the first demonstration of MIC mediated by a pure culture of an acetogen. Other well-known acetogenic bacteria, including Sporomusa ovata and Acetobacterium spp., did not grow well on Fe(0). These results indicate that very few species of acetogens have specific mechanisms to efficiently utilize cathodic electrons derived from Fe(0) oxidation and induce iron corrosion. PMID:25304512

Isolation of acetogenic bacteria that induce biocorrosion by utilizing metallic iron as the sole electron donor.

PubMed

Kato, Souichiro; Yumoto, Isao; Kamagata, Yoichi

2015-01-01

Corrosion of iron occurring under anoxic conditions, which is termed microbiologically influenced corrosion (MIC) or biocorrosion, is mostly caused by microbial activities. Microbial activity that enhances corrosion via uptake of electrons from metallic iron [Fe(0)] has been regarded as one of the major causative factors. In addition to sulfate-reducing bacteria and methanogenic archaea in marine environments, acetogenic bacteria in freshwater environments have recently been suggested to cause MIC under anoxic conditions. However, no microorganisms that perform acetogenesis-dependent MIC have been isolated or had their MIC-inducing mechanisms characterized. Here, we enriched and isolated acetogenic bacteria that induce iron corrosion by utilizing Fe(0) as the sole electron donor under freshwater, sulfate-free, and anoxic conditions. The enriched communities produced significantly larger amounts of Fe(II) than the abiotic controls and produced acetate coupled with Fe(0) oxidation prior to CH4 production. Microbial community analysis revealed that Sporomusa sp. and Desulfovibrio sp. dominated in the enrichments. Strain GT1, which is closely related to the acetogen Sporomusa sphaeroides, was eventually isolated from the enrichment. Strain GT1 grew acetogenetically with Fe(0) as the sole electron donor and enhanced iron corrosion, which is the first demonstration of MIC mediated by a pure culture of an acetogen. Other well-known acetogenic bacteria, including Sporomusa ovata and Acetobacterium spp., did not grow well on Fe(0). These results indicate that very few species of acetogens have specific mechanisms to efficiently utilize cathodic electrons derived from Fe(0) oxidation and induce iron corrosion. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Targeting ideal acceptor-donor materials based on hexabenzocoronene

NASA Astrophysics Data System (ADS)

Santos Silva, H.; Metz, Sebastian; Hiorns, Roger C.; Bégué, D.

2018-06-01

A series of new hybrid donor-acceptor materials based on hexabenzocoronenes (HBC) functionalized with electron donors is investigated by combining a variety of quantum mechanical and molecular dynamic methodologies for use in organic photovoltaic (OPV) devices. Segments of a low band gap alternating copolymer constructed of benzo[1,2-b;3,4-b]dithiophene and thieno[3,4-c]pyrrole-4,6-dione were attached to the conjugated HBC core. The copolymer was chosen for its known high performance in OPVs, and both moieties were singled out due to their exceptional resistance to photo-oxidation, an important requirement for such applications. The macromolecular topology of these systems are expected to induce supra-molecular columns, such as those common to discotic liquid crystals, conducive to the effective percolation of electrons in OPV devices. A challenge with these systems, that of the mixing of the electronic structures of the donor and acceptor moieties that result in excitonic losses and charge recombination, was diminished by trialling a range of linking units. It was found possible to propose ideal donor-acceptor structures with enhanced charge dissociations and transfers in the π-stacking direction for use in OPV and other organic electronic devices.

Organic substrates as electron donors in permeable reactive barriers for removal of heavy metals from acid mine drainage.

PubMed

Kijjanapanich, P; Pakdeerattanamint, K; Lens, P N L; Annachhatre, A P

2012-12-01

This research was conducted to select suitable natural organic substrates as potential carbon sources for use as electron donors for biological sulphate reduction in a permeable reactive barrier (PRB). A number of organic substrates were assessed through batch and continuous column experiments under anaerobic conditions with acid mine drainage (AMD) obtained from an abandoned lignite coal mine. To keep the heavy metal concentration at a constant level, the AMD was supplemented with heavy metals whenever necessary. Under anaerobic conditions, sulphate-reducing bacteria (SRB) converted sulphate into sulphide using the organic substrates as electron donors. The sulphide that was generated precipitated heavy metals as metal sulphides. Organic substrates, which yielded the highest sulphate reduction in batch tests, were selected for continuous column experiments which lasted over 200 days. A mixture of pig-farm wastewater treatment sludge, rice husk and coconut husk chips yielded the best heavy metal (Fe, Cu, Zn and Mn) removal efficiencies of over 90%.

Silica sacrificial layer-assisted in-plane incorporation of Au nanoparticles into mesoporous titania thin films through different reduction methods.

PubMed

Liang, Chih-Peng; Yamauchi, Yusuke; Liu, Chia-Hung; Wu, Kevin C-W

2013-06-28

This study focuses on the incorporation of gold nanoparticles (Au NPs) into our previously synthesized mesoporous titania thin films consisting of titania nanopillars and inverse mesospace (C. W. Wu, T. Ohsuna, M. Kuwabara and K. Kuroda, J. Am. Chem. Soc., 2006, 128, 4544-4545, denoted as MTTFs). Recently, mesoporous titania materials doped with noble metals such as gold have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, photo irradiation, liquid immersion, and vapor contacting) to introduce gold nanoparticles (Au NPs) into MTTFs. The synthesized Au@MTTFs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We further systematically investigated the formation mechanism of gold nanoparticles on the external and internal surfaces of the MTTFs. With the assistance of a silica sacrificial layer, well-dispersed Au NPs with sizes of 4.1 nm were obtained inside the MTTF by photo irradiation. The synthesized Au@MTTF materials show great potential in various photo-electronic and photo-catalytic applications.

Spectrophotometric and spectroscopic studies of charge transfer complexes of p-toluidine as an electron donor with picric acid as an electron acceptor in different solvents.

PubMed

Singh, Neeti; Khan, Ishaat M; Ahmad, Afaq

2010-04-01

The charge transfer complexes of the donor p-toluidine with pi-acceptor picric acid have been studied spectrophotometrically in various solvents such as carbon tetrachloride, chloroform, dichloromethane acetone, ethanol, and methanol at room temperature using absorption spectrophotometer. The results indicate that formation of CTC in non-polar solvent is high. The stoichiometry of the complex was found to be 1:1 ratio by straight-line method between donor and acceptor with maximum absorption bands. The data are discussed in terms of formation constant (K(CT)), molar extinction coefficient (epsilon(CT)), standard free energy (DeltaG(o)), oscillator strength (f), transition dipole moment (mu(EN)), resonance energy (R(N)) and ionization potential (I(D)). The results indicate that the formation constant (K(CT)) for the complex was shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents that were used. Copyright 2010 Elsevier B.V. All rights reserved.

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

Denitrification of the anaerobic membrane bioreactor (AnMBR) effluent with alternative electron donors in domestic wastewater treatment.

PubMed

Pelaz, L; Gómez, A; Garralón, G; Letona, A; Fdz-Polanco, M

2017-11-01

A fixed film bioreactor for the denitrification of the effluent from an anaerobic membrane bioreactor (AnMBR) treating domestic wastewater was designed, built and investigated. After anaerobic treatment, the wastewater usually has a low C/N ratio (∼1.3), and a remaining chemical oxygen demand of around 117mg O 2 /L, which is not enough to make conventional heterotrophic denitrification possible. That effluent also holds methane and sulfide dissolved and oversaturated after leaving the AnMBR. This paper demonstrates the feasibility of using these reduced compounds as electron donors in order to remove 80mg NO x - -N/L at 18°C and 2h of hydraulic retention time. In addition, the influence of the NO 2 - /NO 3 - ratios in the feed was studied. Total nitrogen removal was achieved in all the cases studied, except for a feed with 100% NO 3 - . Methane was the main electron donor used to remove the nitrites and nitrates, with a participation rate of over 70%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Metallization and Biopatterning on Ultra-Flexible Substrates via Dextran Sacrificial Layers

PubMed Central

Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

2014-01-01

Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials. PMID:25153326

Donor-impurity-related optical response and electron Raman scattering in GaAs cone-like quantum dots

NASA Astrophysics Data System (ADS)

Gil-Corrales, A.; Morales, A. L.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.

2017-02-01

The donor-impurity-related optical absorption, relative refractive index changes, and Raman scattering in GaAs cone-like quantum dots are theoretically investigated. Calculations are performed within the effective mass and parabolic band approximations, using the variational procedure to include the electron-impurity correlation effects. The study involves 1 s -like, 2px-like, and 2pz-like states. The conical structure is chosen in such a way that the cone height is large enough in comparison with the base radius thus allowing the use a quasi-analytic solution of the uncorrelated Schrödinger-like electron states.

[Potential Carbon Fixation Capability of Non-photosynthetic Microbial Community at Different Depth of the South China Sea and Its Response to Different Electron Donors].

PubMed

Fang, Feng; Wang, Lei; Xi, Xue-fei; Hu, Jia-jun; Fu, Xiao-hua; Lu, Bing; Xu, Dian-sheng

2015-05-01

The seawater samples collected from many different areas with different depth in the South China Sea were cultivated using different electron donors respectively. And the variation in the potential carbon fixation capability ( PCFC ) of non-photosynthetic microbial community (NPMC) in seawater with different depth was determined after a cycle of cultivation through the statistic analysis. In addition, the cause for the variation was clarified through analyzing key gene abundance regarding CO2 fixation and characteristics of seawater with different depth. The result showed that the PCFCs of NPMC in seawater with different depth were generally low and had no significant difference when using NaNO2 as the electron donor. The PCFC of NPMC in surface seawater was higher than that in deep seawater when using H2 as the electron donor, on the contrary, the PCFC of NPMC in deep seawater was higher than that in surface seawater when using Na2S2O3 as the electron donor. The abundance of the main CO2 fixation gene cbbL in surface seawater was higher than that in deep seawater while the cbbM gene abundance in deep seawater was higher than that in surface seawater. Most hydrogen-oxidizing bacteria had the cbbL gene, and most sulfur bacteria had the cbbM gene. The tendency of seawater cbbL/cbbM gene abundance with the change of depth revealed that there were different kinds of bacteria accounting for the majority in NPMC fixing CO2 at different depth of ocean, which led to different response of PCFC of NPMC at different depth of the sea to different electron donors. The distributions of dissolved oxygen and inorganic carbon concentration with the change of the depth of the sea might be an important reason leading to the difference of NPMC structure and even the difference of PCFC at different depth of the sea.

Reactive Black 5 as electron donor and/or electron acceptor in dual chamber of solar photocatalytic fuel cell.

PubMed

Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusuf, Sara Yasina; Yusoff, NikAthirah; Lee, Sin-Li

2018-07-01

The role of azo dye Reactive Black 5 (RB5) as an electron donor and/or electron acceptor could be distinguished in dual chamber of photocatalytic fuel cell (PFC). The introduction of RB5 in anode chamber increased the voltage generation in the system since degradation of RB5 might produce electrons which also would transfer through external circuit to the cathode chamber. The removal efficiency of RB5 with open and closed circuit was 8.5% and 13.6%, respectively and removal efficiency for open circuit was low due to the fact that recombination of electron-hole pairs might happen in anode chamber since without connection to the cathode, electron cannot be transferred. The degradation of RB5 in cathode chamber with absence of oxygen showed that electrons from anode chamber was accepted by dye molecules to break its azo bond. The presence of oxygen in cathode chamber would improve the oxygen reduction rate which occurred at Platinum-loaded carbon (Pt/C) cathode electrode. The V oc , J sc and P max for different condition of ultrapure water at cathode chamber also affected their fill factor. The transportation of protons to cathode chamber through Nafion membrane could decrease the pH of ultrapure water in cathode chamber and undergo hydrogen evolution reaction in the absence of oxygen which then increased degradation rate of RB5 as well as its electricity generation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Improving first-time donor attendance rates through the use of enhanced donor preparation materials.

PubMed

Masser, Barbara; France, Christopher R; Foot, Jayne; Rozsa, Amy; Hayman, Jane; Waller, Daniel; Hunder, Everard

2016-06-01

Many nondonors are positive about blood donation and this motivates booking an appointment to donate. However, as their appointment approaches barriers to donating-such as anxiety-may become salient and deter attendance. Building on research of France and colleagues demonstrating the positive effect of enhanced preparation materials on donor recruitment, this study sought to determine whether these materials could effectively boost first donation appointment attendance. A field study comprising a 3 (brochure: none, e-mail, hard copy) × 2 (national call center [NCC] contact: none, call) between-subjects design was conducted with 3646 nondonors who had scheduled their first appointment. Participants in the brochure conditions received either a hard copy or an e-mailed link to electronic materials modeled on the donor preparation research of France and colleagues. Participants in the NCC call condition also received a call scripted in line with these preparation materials. The key outcome was new donor attendance rate. Although first-appointment attendance rates were high in the control (no additional contact) condition at 85.07% of those not canceling in advance, dual exposure to the preparation materials through a NCC call and an electronic brochure boosted attendance. The relative risk of attending in the NCC call and electronic brochure condition was 1.0836 (95% confidence interval, 1.0352-1.1343; p = 0.0006), with attendance 8.36% higher than in the control. This gain in attendance came at a relative increase in recruitment costs of 2%. The use of tailored communication to address new donors' concerns and prepare them for donating bolsters attendance rates. © 2016 AABB.

Phenothiazine-anthraquinone donor-acceptor molecules: synthesis, electronic properties and DFT-TDDFT computational study.

PubMed

Zhang, Wen-Wei; Mao, Wei-Li; Hu, Yun-Xia; Tian, Zi-Qi; Wang, Zhi-Lin; Meng, Qing-Jin

2009-09-17

Two donor-acceptor molecules with different pi-electron conjugative units, 1-((10-methyl-10H-phenothiazin-3-yl)ethynyl)anthracene-9,10-dione (AqMp) and 1,1'-(10-methyl-10H-phenothiazine-3,7-diyl)bis(ethyne-2,1-diyl)dianthracene-9,10-dione (Aq2Mp), have been synthesized and investigated for their photochemical and electrochemical properties. Density functional theory (DFT) calculations provide insights into their molecular geometry, electronic structures, and properties. These studies satisfactorily explain the electrochemistry of the two compounds and indicate that larger conjugative effect leads to smaller HOMO-LUMO gap (Eg) in Aq2Mp. Both compounds show ICT and pi --> pi* transitions in the UV-visible range in solution, and Aq2Mp has a bathochromic shift and shows higher oscillator strength of the absorption, which has been verified by time-dependent DFT (TDDFT) calculations. The differences between AqMp and Aq2Mp indicate that the structural and conjugative effects have great influence on the electronic properties of the molecules.

Diversity and Ubiquity of Bacteria Capable of Utilizing Humic Substances as Electron Donors for Anaerobic Respiration

PubMed Central

Coates, John D.; Cole, Kimberly A.; Chakraborty, Romy; O'Connor, Susan M.; Achenbach, Laurie A.

2002-01-01

Previous studies have demonstrated that reduced humic substances (HS) can be reoxidized by anaerobic bacteria such as Geobacter, Geothrix, and Wolinella species with a suitable electron acceptor; however, little is known of the importance of this metabolism in the environment. Recently we investigated this metabolism in a diversity of environments including marine and aquatic sediments, forest soils, and drainage ditch soils. Most-probable-number enumeration studies were performed using 2,6-anthrahydroquinone disulfonate (AHDS), an analog for reduced HS, as the electron donor with nitrate as the electron acceptor. Anaerobic organisms capable of utilizing reduced HS as an electron donor were found in all environments tested and ranged from a low of 2.31 × 101 in aquifer sediments to a high of 9.33 × 106 in lake sediments. As part of this study we isolated six novel organisms capable of anaerobic AHDS oxidation. All of the isolates coupled the oxidation of AHDS to the reduction of nitrate with acetate (0.1 mM) as the carbon source. In the absence of cells, no AHDS oxidation was apparent, and in the absence of AHDS, no cell density increase was observed. Generally, nitrate was reduced to N2. Analysis of the AHDS and its oxidized form, 2,6-anthraquinone disulfonate (AQDS), in the medium during growth revealed that the anthraquinone was not being biodegraded as a carbon source and was simply being oxidized as an energy source. Determination of the AHDS oxidized and nitrate reduced accounted for 109% of the theoretical electron transfer. In addition to AHDS, all of these isolates could also couple the oxidation of reduced humic substances to the reduction of nitrate. No HS oxidation occurred in the absence of cells and in the absence of a suitable electron acceptor, demonstrating that these organisms were capable of utilizing natural HS as an energy source and that AHDS serves as a suitable analog for studying this metabolism. Alternative electron donors included

Diversity and ubiquity of bacteria capable of utilizing humic substances as electron donors for anaerobic respiration.

PubMed

Coates, John D; Cole, Kimberly A; Chakraborty, Romy; O'Connor, Susan M; Achenbach, Laurie A

2002-05-01

Previous studies have demonstrated that reduced humic substances (HS) can be reoxidized by anaerobic bacteria such as Geobacter, Geothrix, and Wolinella species with a suitable electron acceptor; however, little is known of the importance of this metabolism in the environment. Recently we investigated this metabolism in a diversity of environments including marine and aquatic sediments, forest soils, and drainage ditch soils. Most-probable-number enumeration studies were performed using 2,6-anthrahydroquinone disulfonate (AHDS), an analog for reduced HS, as the electron donor with nitrate as the electron acceptor. Anaerobic organisms capable of utilizing reduced HS as an electron donor were found in all environments tested and ranged from a low of 2.31 x 10(1) in aquifer sediments to a high of 9.33 x 10(6) in lake sediments. As part of this study we isolated six novel organisms capable of anaerobic AHDS oxidation. All of the isolates coupled the oxidation of AHDS to the reduction of nitrate with acetate (0.1 mM) as the carbon source. In the absence of cells, no AHDS oxidation was apparent, and in the absence of AHDS, no cell density increase was observed. Generally, nitrate was reduced to N(2). Analysis of the AHDS and its oxidized form, 2,6-anthraquinone disulfonate (AQDS), in the medium during growth revealed that the anthraquinone was not being biodegraded as a carbon source and was simply being oxidized as an energy source. Determination of the AHDS oxidized and nitrate reduced accounted for 109% of the theoretical electron transfer. In addition to AHDS, all of these isolates could also couple the oxidation of reduced humic substances to the reduction of nitrate. No HS oxidation occurred in the absence of cells and in the absence of a suitable electron acceptor, demonstrating that these organisms were capable of utilizing natural HS as an energy source and that AHDS serves as a suitable analog for studying this metabolism. Alternative electron donors included

Electron-transfer and acid-base properties of a two-electron oxidized form of quaterpyrrole that acts as both an electron donor and an acceptor.

PubMed

Zhang, Min; E, Wenbo; Ohkubo, Kei; Sanchez-Garcia, David; Yoon, Dae-Wi; Sessler, Jonathan L; Fukuzumi, Shunichi; Kadish, Karl M

2008-02-21

Electron-transfer interconversion between the four-electron oxidized form of a quaterpyrrole (abbreviated as P4 for four pyrroles) and the two-electron oxidized form (P4H2) as well as between P4H2 and its fully reduced form (P4H4) bearing analogous substituents in the alpha- and beta-pyrrolic positions was studied by means of cyclic voltammetry and UV-visible spectroelectrochemistry combined with ESR and laser flash photolysis measurements. The two-electron oxidized form, P4H2, acts as both an electron donor and an electron acceptor. The radical cation (P4H2*+) and radical anion (P4H2*-) are both produced by photoinduced electron transfer from dimeric 1-benzyl-1,4-dihydronicotinamide to P4H2, whereas the cation radical form of the compound is also produced by electron-transfer oxidation of P4H2 with [Ru(bpy)3]3+. The ESR spectra of P4H2*+ and P4H2*- were recorded at low temperature and exhibit spin delocalization over all four pyrrole units. Thus, the two-electron oxidized form of the quaterpyrrole (P4H2) displays redox and electronic features analogous to those seen in the case of porphyrins and may be considered as a simple, open-chain model of this well-studied tetrapyrrolic macrocycle. The dynamics of deprotonation from P4H2*+ and disproportionation of P4H2 were examined by laser flash photolysis measurements of photoinduced electron-transfer oxidation and reduction of P4H2, respectively.

Chemostat Studies of TCE-Dehalogenating Anaerobic Consortia under Excess and Limited Electron Donor Addition

NASA Astrophysics Data System (ADS)

Semprini, L.; Azizian, M.; Green, J.; Mayer-Blackwell, K.; Spormann, A. M.

2015-12-01

Two cultures - the Victoria Strain (VS) and the Evanite Strain (EV), enriched with the organohalide respiring bacteria Dehalococcoides mccartyi - were grown in chemostats for more than 4 years at a mean cell residence time of 50 days. The slow doubling rate represents growth likely experienced in the subsurface. The chemostats were fed formate as an electron donor and trichloroethene (TCE) as the terminal electron acceptor. Under excess formate conditions, stable operation was observed with respect to TCE transformation, steady-state hydrogen (H2) concentrations (40 nM), and the structure of the dehalogenating community. Both cultures completely transformed TCE to ethene, with minor amounts of vinyl chloride (VC) observed, along with acetate formation. When formate was limited, TCE was transformed incompletely to ethene (40-60%) and VC (60- 40%), and H2 concentrations ranged from 1 to 3 nM. The acetate concentration dropped below detection. Batch kinetic studies of TCE transformation with chemostat harvested cells found transformation rates of c-DCE and VC were greatly reduced when the cells were grown with limited formate. Upon increasing formate addition to the chemostats, from limited to excess, essentially complete transformation of TCE to ethene was achieved. The increase in formate was associated with an increase in H2 concentration and the production of acetate. Results of batch kinetic tests showed increases in transformation rates for TCE and c-DCE by factors of 3.5 and 2.5, respectively, while VC rates increased by factors of 33 to 500, over a six month period. Molecular analysis of chemostat samples is being performed to quantify the changes in copy numbers of reductase genes and to determine whether shifts in the strains of Dehalococcoides mccartyi where responsible for the observed rate increases. The results demonstrate the importance of electron donor supply for successful in-situ remediation.

Synthesis and photophysical properties of new catenated electron donor-acceptor materials with magnesium and free base porphyrins as donors and C60 as the acceptor

NASA Astrophysics Data System (ADS)

Kirner, Sabrina V.; Guldi, Dirk M.; Megiatto, Jackson D., Jr.; Schuster, David I.

2014-12-01

A new series of nanoscale electron donor-acceptor systems with [2]catenane architectures has been synthesized, incorporating magnesium porphyrin (MgP) or free base porphyrin (H2P) as electron donor and C60 as electron acceptor, surrounding a central tetrahedral Cu(i)-1,10-phenanthroline (phen) complex. Model catenated compounds incorporating only one or none of these photoactive moieties were also prepared. The synthesis involved the use of Sauvage's metal template protocol in combination with the 1,3-dipolar cycloaddition of azides and alkynes (``click chemistry''), as in other recent reports from our laboratories. Ground state electron interactions between the individual constituents was probed using electrochemistry and UV-vis absorption spectroscopy, while events occurring following photoexcitation in tetrahydrofuran (under both aerobic and anaerobic conditions) at various wavelengths were followed by means of time-resolved transient absorption and emission spectroscopies on the femtosecond and nanosecond time scales, respectively, complemented by measurements of quantum yields for generation of singlet oxygen. From similar studies with model catenates containing one or neither of the chromophores, the events following photoexcitation could be elucidated. The results were compared with those previously reported for analogous catenates based on zinc porphyrin (ZnP). It was determined that a series of energy transfer (EnT) and electron transfer (ET) processes take place in the present catenates, ultimately generating long-distance charge separated (CS) states involving oxidized porphyrin and reduced C60 moieties, with lifetimes ranging from 400 to 1060 nanoseconds. Shorter lived short-distance CS states possessing oxidized copper complexes and reduced C60, with lifetimes ranging from 15 to 60 ns, were formed en route to the long-distance CS states. The dynamics of the ET processes were analyzed in terms of their thermodynamic driving forces. It was clear that

Electron Donors Supporting Growth and Electroactivity of Geobacter sulfurreducens Anode Biofilms

PubMed Central

Speers, Allison M.

2012-01-01

Geobacter bacteria efficiently oxidize acetate into electricity in bioelectrochemical systems, yet the range of fermentation products that support the growth of anode biofilms and electricity production has not been thoroughly investigated. Here, we show that Geobacter sulfurreducens oxidized formate and lactate with electrodes and Fe(III) as terminal electron acceptors, though with reduced efficiency compared to acetate. The structure of the formate and lactate biofilms increased in roughness, and the substratum coverage decreased, to alleviate the metabolic constraints derived from the assimilation of carbon from the substrates. Low levels of acetate promoted formate carbon assimilation and biofilm growth and increased the system's performance to levels comparable to those with acetate only. Lactate carbon assimilation also limited biofilm growth and led to the partial oxidization of lactate to acetate. However, lactate was fully oxidized in the presence of fumarate, which redirected carbon fluxes into the tricarboxylic acid (TCA) cycle, and by acetate-grown biofilms. These results expand the known ranges of electron donors for Geobacter-driven fuel cells and identify microbial constraints that can be targeted to develop better-performing strains and increase the performance of bioelectrochemical systems. PMID:22101036

Intramolecular Charge-Transfer Interaction of Donor-Acceptor-Donor Arrays Based on Anthracene Bisimide.

PubMed

Iwanaga, Tetsuo; Ogawa, Marina; Yamauchi, Tomokazu; Toyota, Shinji

2016-05-20

We designed anthracene bisimide (ABI) derivatives having two triphenylamine (TPA) groups as donor units at the 9,10-positions to form a novel π-conjugated donor-acceptor system. These compounds and their analogues with ethynylene linkers were synthesized by Suzuki-Miyaura and Sonogashira coupling reactions, respectively. In UV-vis spectra, the linker-free derivatives showed broad absorption bands arising from intramolecular charge-transfer interactions. Introducing ethynylene linkers resulted in a considerable red shift of the absorption bands. In fluorescence spectra, the ethynylene derivatives showed intense emission bands at 600-650 nm. Their photophysical and electrochemical properties were compared with those of the corresponding mono TPA derivatives on the basis of theoretical calculations and cyclic voltammetry to evaluate the intramolecular electronic interactions between the donor and acceptor units.

Influence of Different Electron Donors and Acceptors on Dehalorespiration of Tetrachloroethene by Desulfitobacterium frappieri TCE1

PubMed Central

Gerritse, Jan; Drzyzga, Oliver; Kloetstra, Geert; Keijmel, Mischa; Wiersum, Luit P.; Hutson, Roger; Collins, Matthew D.; Gottschal, Jan C.

1999-01-01

Strain TCE1, a strictly anaerobic bacterium that can grow by reductive dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE), was isolated by selective enrichment from a PCE-dechlorinating chemostat mixed culture. Strain TCE1 is a gram-positive, motile, curved rod-shaped organism that is 2 to 4 by 0.6 to 0.8 μm and has approximately six lateral flagella. The pH and temperature optima for growth are 7.2 and 35°C, respectively. On the basis of a comparative 16S rRNA sequence analysis, this bacterium was identified as a new strain of Desulfitobacterium frappieri, because it exhibited 99.7% relatedness to the D. frappieri type strain, strain PCP-1. Growth with H2, formate, l-lactate, butyrate, crotonate, or ethanol as the electron donor depends on the availability of an external electron acceptor. Pyruvate and serine can also be used fermentatively. Electron donors (except formate and H2) are oxidized to acetate and CO2. When l-lactate is the growth substrate, strain TCE1 can use the following electron acceptors: PCE and TCE (to produce cis-1,2-dichloroethene), sulfite and thiosulfate (to produce sulfide), nitrate (to produce nitrite), and fumarate (to produce succinate). Strain TCE1 is not able to reductively dechlorinate 3-chloro-4-hydroxyphenylacetate. The growth yields of the newly isolated bacterium when PCE is the electron acceptor are similar to those obtained for other dehalorespiring anaerobes (e.g., Desulfitobacterium sp. strain PCE1 and Desulfitobacterium hafniense) and the maximum specific reductive dechlorination rates are 4 to 16 times higher (up to 1.4 μmol of chloride released · min−1 · mg of protein−1). Dechlorination of PCE and TCE is an inducible process. In PCE-limited chemostat cultures of strain TCE1, dechlorination is strongly inhibited by sulfite but not by other alternative electron acceptors, such as fumarate or nitrate. PMID:10583967

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.

'Utilitarian' judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good.

PubMed

Kahane, Guy; Everett, Jim A C; Earp, Brian D; Farias, Miguel; Savulescu, Julian

2015-01-01

A growing body of research has focused on so-called 'utilitarian' judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such 'utilitarian' judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between 'utilitarian' judgment in such sacrificial dilemmas and a range of traits, attitudes, judgments and behaviors that either reflect or reject an impartial concern for the greater good of all. In Study 1, we found that rates of 'utilitarian' judgment were associated with a broadly immoral outlook concerning clear ethical transgressions in a business context, as well as with sub-clinical psychopathy. In Study 2, we found that 'utilitarian' judgment was associated with greater endorsement of rational egoism, less donation of money to a charity, and less identification with the whole of humanity, a core feature of classical utilitarianism. In Studies 3 and 4, we found no association between 'utilitarian' judgments in sacrificial dilemmas and characteristic utilitarian judgments relating to assistance to distant people in need, self-sacrifice and impartiality, even when the utilitarian justification for these judgments was made explicit and unequivocal. This lack of association remained even when we controlled for the antisocial element in 'utilitarian' judgment. Taken together, these results suggest that there is very little relation between sacrificial judgments in the hypothetical dilemmas that dominate current research, and a genuine utilitarian approach to ethics. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Field evaluation of a new aluminum alloy as a sacrificial anode for steel embedded in concrete

DOT National Transportation Integrated Search

1998-04-01

This is the final report for a study to evaluate the use of sacrificial cathodic protection for reinforced and prestressed concrete bridge members. Cathodic protection (CP) using impressed current is an accepted and common method used to provide corr...

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

PubMed Central

Hao, Yan; Yang, Wenxing; Zhang, Lei; Jiang, Roger; Mijangos, Edgar; Saygili, Yasemin; Hammarström, Leif; Hagfeldt, Anders; Boschloo, Gerrit

2016-01-01

Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy—by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte—to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system. PMID:28000672

Dissimilatory arsenate reduction with sulfide as electron donor: Experiments with Mono Lake water and isolation of strain MLMS-1, a chemoautotrophic arsenate respirer

USGS Publications Warehouse

Hoeft, S.E.; Kulp, T.R.; Stolz, J.F.; Hollibaugh, J.T.; Oremland, R.S.

2004-01-01

Anoxic bottom water from Mono Lake, California, can biologically reduce added arsenate without any addition of electron donors. Of the possible in situ inorganic electron donors present, only sulfide was sufficiently abundant to drive this reaction. We tested the ability of sulfide to serve as an electron donor for arsenate reduction in experiments with lake water. Reduction of arsenate to arsenite occurred simultaneously with the removal of sulfide. No loss of sulfide occurred in controls without arsenate or in sterilized samples containing both arsenate and sulfide. The rate of arsenate reduction in lake water was dependent on the amount of available arsenate. We enriched for a bacterium that could achieve growth with sulfide and arsenate in a defined, mineral medium and purified it by serial dilution. The isolate, strain MLMS-1, is a gram-negative, motile curved rod that grows by oxidizing sulfide to sulfate while reducing arsenate to arsenite. Chemoautotrophy was confirmed by the incorporation of H14CO3- into dark-incubated cells, but preliminary gene probing tests with primers for ribulose-1,5-biphosphate carboxylase/oxygenase did not yield PCR-amplified products. Alignment of 16S rRNA sequences indicated that strain MLMS-1 was in the ??-Proteobacteria, located near sulfate reducers like Desulfobulbus sp. (88 to 90% similarity) but more closely related (97%) to unidentified sequences amplified previously from Mono Lake. However, strain MLMS-1 does not grow with sulfate as its electron 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.

‘Utilitarian’ judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good

PubMed Central

Kahane, Guy; Everett, Jim A.C.; Earp, Brian D.; Farias, Miguel; Savulescu, Julian

2015-01-01

A growing body of research has focused on so-called ‘utilitarian’ judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such ‘utilitarian’ judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between ‘utilitarian’ judgment in such sacrificial dilemmas and a range of traits, attitudes, judgments and behaviors that either reflect or reject an impartial concern for the greater good of all. In Study 1, we found that rates of ‘utilitarian’ judgment were associated with a broadly immoral outlook concerning clear ethical transgressions in a business context, as well as with sub-clinical psychopathy. In Study 2, we found that ‘utilitarian’ judgment was associated with greater endorsement of rational egoism, less donation of money to a charity, and less identification with the whole of humanity, a core feature of classical utilitarianism. In Studies 3 and 4, we found no association between ‘utilitarian’ judgments in sacrificial dilemmas and characteristic utilitarian judgments relating to assistance to distant people in need, self-sacrifice and impartiality, even when the utilitarian justification for these judgments was made explicit and unequivocal. This lack of association remained even when we controlled for the antisocial element in ‘utilitarian’ judgment. Taken together, these results suggest that there is very little relation between sacrificial judgments in the hypothetical dilemmas that dominate current research, and a genuine utilitarian approach to ethics. PMID:25460392

Design of a New Fused-Ring Electron Acceptor with Excellent Compatibility to Wide-Bandgap Polymer Donors for High-Performance Organic Photovoltaics.

PubMed

Liu, Wenrui; Zhang, Jianyun; Zhou, Zichun; Zhang, Dongyang; Zhang, Yuan; Xu, Shengjie; Zhu, Xiaozhang

2018-05-16

Fused-ring electron acceptors (FREAs) have recently received intensive attention. Besides the continuing development of new FREAs, the demand for FREAs featuring good compatibility to donor materials is becoming more and more urgent, which is highly desirable for screening donor materials and achieving new breakthroughs. In this work, a new FREA is developed, ZITI, featuring an octacyclic dithienocyclopentaindenoindene central core. The core is designed by linking 2,7-dithienyl substituents and indenoindene with small methylene groups, in which the indeno[1,2-b]thiophene-2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile part provides a large and unoccupied π-surface. Most notably, ZITI possesses an excellent compatibility with commercially available polymer donors, delivering very high power conversion efficiencies of over 13%. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Arsenite as an electron donor for anoxygenic photosynthesis: Description of three strains of Ectothiorhodospria from Mono Lake, California, and Big Soda Lake, Nevada

USGS Publications Warehouse

McCann, Shelley; Boren, Alison; Hernandez-Maldonado, Jaime; Stoneburner, Brendon; Saltikov, Chad W; Stolz, John F.; Oremland, Ronald S.

2017-01-01

Three novel strains of photosynthetic bacteria from the family Ectothiorhodospiraceae were isolated from soda lakes of the Great Basin Desert, USA by employing arsenite (As(III)) as the sole electron donor in the enrichment/isolation process. Strain PHS-1 was previously isolated from a hot spring in Mono Lake, while strain MLW-1 was obtained from Mono Lake sediment, and strain BSL-9 was isolated from Big Soda Lake. Strains PHS-1, MLW-1, and BSL-9 were all capable of As(III)-dependent growth via anoxygenic photosynthesis and contained homologs of arxA, but displayed different phenotypes. Comparisons were made with three related species: Ectothiorhodospira shaposhnikovii DSM 2111, Ectothiorhodospira shaposhnikovii DSM 243T, and Halorhodospira halophila DSM 244. All three type cultures oxidized arsenite to arsenate but did not grow with As(III) as the sole electron donor. DNA–DNA hybridization indicated that strain PHS-1 belongs to the same species as Ect. shaposhnikovii DSM 2111 (81.1% sequence similarity), distinct from Ect. shaposhnikovii DSM 243T (58.1% sequence similarity). These results suggest that the capacity for light-driven As(III) oxidation is a common phenomenon among purple photosynthetic bacteria in soda lakes. However, the use of As(III) as a sole electron donor to sustain growth via anoxygenic photosynthesis is confined to novel isolates that were screened for by this selective cultivation criterion.

Sacrificial bonds and hidden length in biomaterials: A kinetic constitutive description of strength and toughness in bone

NASA Astrophysics Data System (ADS)

Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

2013-07-01

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

The electronic structure and second-order nonlinear optical properties of donor-acceptor acetylenes - A detailed investigation of structure-property relationships

NASA Technical Reports Server (NTRS)

Stiegman, A. E.; Graham, Eva; Khundkar, Lutfur R.; Perry, Joseph W.; Cheng, L.-T.; Perry, Kelly J.

1991-01-01

A series of donor-acceptor acetylene compounds was synthesized in which systematic changes in both the conjugation length and the donor-acceptor strength were made. The effect of these structural changes on the spectroscopic and electronic properties of the molecules and, ultimately, on the measured second-order molecular hyperpolarizabilities (beta) was investigated. It was found that increases in the donor-acceptor strength resulted in increases in the magnitude of beta. For this class of molecules, the increase is dominated by the energy of the intramolecular charge-transfer transition, while factors such as the ground to excited-state dipole moment change and the transition-moment integral are much less important. Increasing the conjugation length from one to two acetylene linkers did not result in an increase in the value of beta; however, beta increased sharply in going from two acetylenes to three. This increase is attributed to the superposition of several nearly isoenergetic excited states.

Dissimilatory arsenate reduction with sulfide as the electron donor--Experiments with Mono Lake water and isolation of strain MLMS-1, a chemoautotrophic arsenate-respirer

USGS Publications Warehouse

Hoeft, Shelley E.; Kulp, Thomas R.; Stolz, John F.; Hollibaugh, James T.; Oremland, Ronald S.

2004-01-01

Anoxic bottom water from Mono Lake, California, can biologically reduce added arsenate without any addition of electron donors. Of the possible in situ inorganic electron donors present, only sulfide was sufficiently abundant to drive this reaction. We tested the ability of sulfide to serve as an electron donor for arsenate reduction in experiments with lake water. Reduction of arsenate to arsenite occurred simultaneously with the removal of sulfide. No loss of sulfide occurred in controls without arsenate or in sterilized samples containing both arsenate and sulfide. The rate of arsenate reduction in lake water was dependent on the amount of available arsenate. We enriched for a bacterium that could achieve growth with sulfide and arsenate in a defined, mineral medium and purified it by serial dilution. The isolate, strain MLMS-1, is a gram-negative, motile curved rod that grows by oxidizing sulfide to sulfate while reducing arsenate to arsenite. Chemoautotrophy was confirmed by the incorporation of H14CO3− into dark-incubated cells, but preliminary gene probing tests with primers for ribulose-1,5-biphosphate carboxylase/oxygenase did not yield PCR-amplified products. Alignment of 16S rRNA sequences indicated that strain MLMS-1 was in the δ-Proteobacteria, located near sulfate reducers like Desulfobulbus sp. (88 to 90% similarity) but more closely related (97%) to unidentified sequences amplified previously from Mono Lake. However, strain MLMS-1 does not grow with sulfate as its electron acceptor.

Statistical exchange-coupling errors and the practicality of scalable silicon donor qubits

NASA Astrophysics Data System (ADS)

Song, Yang; Das Sarma, S.

2016-12-01

Recent experimental efforts have led to considerable interest in donor-based localized electron spins in Si as viable qubits for a scalable silicon quantum computer. With the use of isotopically purified 28Si and the realization of extremely long spin coherence time in single-donor electrons, the recent experimental focus is on two-coupled donors with the eventual goal of a scaled-up quantum circuit. Motivated by this development, we simulate the statistical distribution of the exchange coupling J between a pair of donors under realistic donor placement straggles, and quantify the errors relative to the intended J value. With J values in a broad range of donor-pair separation ( 5 <|R |<60 nm), we work out various cases systematically, for a target donor separation R0 along the [001], [110] and [111] Si crystallographic directions, with |R0|=10 ,20 or 30 nm and standard deviation σR=1 ,2 ,5 or 10 nm. Our extensive theoretical results demonstrate the great challenge for a prescribed J gate even with just a donor pair, a first step for any scalable Si-donor-based quantum computer.

Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

PubMed

Tait, Zachary S; Thompson, Megan; Stubbins, Aron

2015-07-01

The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Organic photosensitizers with a heteroleptic dual donor for dye-sensitized solar cells.

PubMed

Kim, Joo Young; Kim, Young Sik

2012-04-01

Using DFT and TDDFT calculations, we investigated the substitution effect in the electronic and optical properties of dye sensitizers with a dual donor composed of triphenylamine and/or indoline moieties. Due to replacement with the dual donor moieties, the HOMO levels were split into HOMO and HOMO - 1 levels, and the bandgaps between the HOMO and LUMO levels decreased, leading to the creation of bathochromically extended absorption spectra. Nearly degenerated splitting of the HOMO levels resulted from the similarity of the electronic structure between the HOMO and the HOMO - 1 levels, delocalized over both dual-donor moieties, when replacing the dual donors. It was shown that the additional electron-donating group creates an additional absorption band and causes a cascading two-electron process aiding the charge separation process. Owing to a more panchromatic attribute, easier energy transfer and feasible retardation of the recombination between the injected electrons and the electrolyte, it is expected that dyeTI will show better performance than the other dyes (dyeT dyeTT and dyeIT) as denoted here in terms of the conversion efficiency of dye-sensitized solar cells (DSSCs). This work presents the probable benefits of dye sensitizers with dual-donor moieties and provides insight into the development of more efficient dye sensitizers for DSSCs through modification of the Frontier molecular orbitals.

The ETHANOL-CO_2 Dimer is AN Electron Donor-Acceptor Complex

NASA Astrophysics Data System (ADS)

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

2017-06-01

Supercritical (sc) CO_2 is a common industrial solvent for the extraction of caffeine, nicotine, petrochemicals, and natural products. The ability of apolar scCO_2 to dissolve polar solutes is greatly enhanced by the addition of a polar co-solvent, often methanol or ethanol. Experimental and theoretical work show that methanol interactions in scCO_2 are predominantly hydrogen bonding, while the gas-phase complex is an electron donor-acceptor (EDA) configuration. Ethanol, meanwhile, is predicted to form EDA complexes both in scCO_2 and in the gas phase, but there have been no experimental measurements to support this conclusion. Here, we report a combined chirped-pulse and cavity FTMW study of the ethanol-CO_2 complex. Comparison with theory indicates the EDA complex is dominant under our experimental conditions. We confirm the structure with isotopic substitution, and derive a semi-experimental equilibrium structure. Our results are consistent with theoretical predictions that the linearity of the CO_2 subgroup is broken by the complexation interaction.

Influence of the Terminal Electron Donor in D-D-π-A Organic Dye-Sensitized Solar Cells: Dithieno[3,2-b:2',3'-d]pyrrole versus Bis(amine).

PubMed

Dai, Panpan; Yang, Lin; Liang, Mao; Dong, Huanhuan; Wang, Peng; Zhang, Chunyao; Sun, Zhe; Xue, Song

2015-10-14

With respect to the electron-withdrawing acceptors of D-A-π-A organic dyes, reports on the second electron-donating donors for D-D-π-A organic dyes are very limited. Both of the dyes have attracted significant attention in the field of dye-sensitized solar cells (DSCs). In this work, four new D-D-π-A organic dyes with dithieno[3,2-b:2',3'-d]pyrrole (DTP) or bis(amine) donor have been designed and synthesized for a investigation of the influence of the terminal electron donor in D-D-π-A organic dye-sensitized solar cells. It is found that DTP is a promising building block as the terminal electron donor when introduced in the dithiophenepyrrole direction, but not just a good bridge, which exhibits several characteristics: (i) efficiently increasing the maximum molar absorption coefficient and extending the absorption bands; (ii) showing stronger charge transfer interaction as compared with the pyrrole direction; (iii) beneficial to photocurrent generation of DSCs employing cobalt electrolytes. DSCs based on M45 with the Co-phen electrolyte exhibit good light-to-electric energy conversion efficiencies as high as 9.02%, with a short circuit current density (JSC) of 15.3 mA cm(-2), open circuit voltage (VOC) of 867 mV and fill factor (FF) of 0.68 under AM 1.5 illumination (100 mW cm(-2)). The results demonstrate that N,S-heterocycles such as DTP unit could be promising candidates for application in highly efficient DSCs employing cobalt electrolyte.

In situ Bioreduction of Uranium (VI) in Groundwater and Sediments with Edible Oil as the Electron Donor

NASA Astrophysics Data System (ADS)

Wu, W.; Watson, D. B.; Mehlhorn, T.; Zhang, G.; Earles, J.; Lowe, K.; Phillips, J.; Boyanov, M.; Kemner, K. M.; Schadt, C. W.; Brooks, S. C.; Criddle, C.; Jardine, P.

2009-12-01

In situ bioremediation of a uranium-contaminated aquifer was conducted at the US DOE Environmental Remediation Sciences Program (ERSP) Integrated Field Research Challenge (IFRC) site, in Oak Ridge, TN. Edible oil was tested as a slow-release electron donor for microbially mediated U (VI) reduction. Uranium contaminated sediments from the site were used in laboratory microcosm tests to study the feasibility of using this electron donor under anaerobic, ambient temperature conditions. Parallel microcosms were established using ethanol as electron donor for comparison. The tests also examined the impact of sulfate concentrations on U (VI) reduction. The oil was degraded by indigenous microorganisms with acetate as a major product but at a much slower rate than ethanol. The rapid removal of U (VI) from the aqueous phase occurred concurrently with acetate production and sulfate reduction. Initial U(VI) concentration in the aqueous phase increased with increased sulfate concentration (1 vs. 5 mM), likely due to U(VI) desorption from the solid phase, but more U(VI) was reduced with higher initial sulfate level. Finally, the bioreaction in microcosms progressed to methanogenesis. Subsequently, a field test with the edible oil was conducted in a highly permeable gravelly layer (hydraulic conductivity 0.076 cm/sec). Groundwater at the site contained 5-6 μM U; 1.0-1.2 mM sulfate; 3-4 mM Ca; pH 6.8. Diluted emulsified oil (20% solution) was injected into three injection wells within 2 hrs. Geochemical analysis of site groundwater demonstrated the sequential reduction of nitrate, Mn, Fe(III) and sulfate. Transient accumulation of acetate was observed as an intermediate in the oil degradation. Reduction and removal of uranium from groundwater was observed in all wells connected to the injection wells after 2-4 weeks. Uranium concentrations in groundwater were reduced to below 0.126 μM (EPA drinking water standard), at some well locations. Rebound of U in groundwater was

Edge-on and face-on functionalized Pc on enriched semiconducting SWCNT hybrids.

PubMed

Arellano, Luis M; Martín-Gomis, Luis; Gobeze, Habtom B; Molina, Desiré; Hermosa, Cristina; Gómez-Escalonilla, María J; Fierro, José Luis G; Sastre-Santos, Ángela; D'Souza, Francis; Langa, Fernando

2018-03-15

Enriched semiconducting single-walled carbon nanotubes (SWCNT (6,5) and SWCNT (7,6)) and HiPco nanotubes were covalently functionalized with either zinc phthalocyanine or silicon phthalocyanine as electron donors. The synthetic strategy resulted in edge-on and face-on geometries with respect to the phthalocyanine geometry, with both phthalocyanines held by an electronically conducting diphenylacetylene linker. The extent of functionalization in the MPc-SWCNT (M = Zn or Si) donor-acceptor nanohybrids was determined by systematic studies involving AFM, TGA, XPS, optical and Raman techniques. Intramolecular interactions in MPc-SWCNT nanohybrids were probed by studies involving optical absorbance, Raman, luminescence and electrochemical studies. Different degrees of interactions were observed depending on the type of MPc and mode of attachment. Substantial quenching of MPc fluorescence in these hybrids was observed from steady-state and three-dimensional fluorescence mapping, which suggests the occurrence of excited state events. Evidence for the occurrence of excited state charge transfer type interactions was subsequently secured from femtosecond transient absorption studies covering both the visible and near-infrared regions. Furthermore, electron-pooling experiments performed in the presence of a sacrificial electron donor and a second electron acceptor revealed accumulation of one-electron reduced product upon continuous irradiation of the nanohybrids. In such experiments, the ZnPc-SWCNT (6,5) nanohybrid outperformed other nanohybrids and this suggests that this is a superior donor-acceptor system for photocatalytic applications.

Impact of Organic Carbon Electron Donors on Microbial Community Development under Iron- and Sulfate-Reducing Conditions

DOE PAGES

Kwon, Man Jae; O’Loughlin, Edward J.; Boyanov, Maxim I.; ...

2016-01-22

Although iron- and sulfate-reducing bacteria in subsurface environments have crucial roles in biogeochemical cycling of C, Fe, and S, how specific electron donors impact the compositional structure and activity of native iron- and/or sulfate-reducing communities is largely unknown. To understand this better, we created bicarbonate-buffered batch systems in duplicate with three different electron donors (acetate, lactate, or glucose) paired with ferrihydrite and sulfate as the electron acceptors and inoculated them with subsurface sediment as the microbial inoculum. Sulfate and ferrihydrite reduction occurred simultaneously and were faster with lactate than with acetate. 16S rRNA-based sequence analysis of the communities over timemore » revealed that Desulfotomaculum was the major driver for sulfate reduction coupled with propionate oxidation in lactate-amended incubations. The reduction of sulfate resulted in sulfide production and subsequent abiotic reduction of ferrihydrite. In contrast, glucose promoted faster reduction of ferrihydrite, but without reduction of sulfate. Interestingly, the glucose-amended incubations led to two different biogeochemical trajectories among replicate bottles that resulted in distinct coloration (white and brown). The two outcomes in geochemical evolution might be due to the stochastic evolution of the microbial communities or subtle differences in the initial composition of the fermenting microbial community and its development via the use of different glucose fermentation pathways available within the community. Synchrotron-based x-ray analysis indicated that siderite and amorphous Fe(II) were formed in the replicate bottles with glucose, while ferrous sulfide and vivianite were formed with lactate or acetate. As a result, these data sets reveal that use of different C utilization pathways projects significant changes in microbial community composition over time that uniquely impact both the geochemistry and mineralogy of

Impact of Organic Carbon Electron Donors on Microbial Community Development under Iron- and Sulfate-Reducing Conditions

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

Kwon, Man Jae; O’Loughlin, Edward J.; Boyanov, Maxim I.

Although iron- and sulfate-reducing bacteria in subsurface environments have crucial roles in biogeochemical cycling of C, Fe, and S, how specific electron donors impact the compositional structure and activity of native iron- and/or sulfate-reducing communities is largely unknown. To understand this better, we created bicarbonate-buffered batch systems in duplicate with three different electron donors (acetate, lactate, or glucose) paired with ferrihydrite and sulfate as the electron acceptors and inoculated them with subsurface sediment as the microbial inoculum. Sulfate and ferrihydrite reduction occurred simultaneously and were faster with lactate than with acetate. 16S rRNA-based sequence analysis of the communities over timemore » revealed that Desulfotomaculum was the major driver for sulfate reduction coupled with propionate oxidation in lactate-amended incubations. The reduction of sulfate resulted in sulfide production and subsequent abiotic reduction of ferrihydrite. In contrast, glucose promoted faster reduction of ferrihydrite, but without reduction of sulfate. Interestingly, the glucose-amended incubations led to two different biogeochemical trajectories among replicate bottles that resulted in distinct coloration (white and brown). The two outcomes in geochemical evolution might be due to the stochastic evolution of the microbial communities or subtle differences in the initial composition of the fermenting microbial community and its development via the use of different glucose fermentation pathways available within the community. Synchrotron-based x-ray analysis indicated that siderite and amorphous Fe(II) were formed in the replicate bottles with glucose, while ferrous sulfide and vivianite were formed with lactate or acetate. As a result, these data sets reveal that use of different C utilization pathways projects significant changes in microbial community composition over time that uniquely impact both the geochemistry and mineralogy of

Impact of Organic Carbon Electron Donors on Microbial Community Development under Iron- and Sulfate-Reducing Conditions.

PubMed

Kwon, Man Jae; O'Loughlin, Edward J; Boyanov, Maxim I; Brulc, Jennifer M; Johnston, Eric R; Kemner, Kenneth M; Antonopoulos, Dionysios A

2016-01-01

Although iron- and sulfate-reducing bacteria in subsurface environments have crucial roles in biogeochemical cycling of C, Fe, and S, how specific electron donors impact the compositional structure and activity of native iron- and/or sulfate-reducing communities is largely unknown. To understand this better, we created bicarbonate-buffered batch systems in duplicate with three different electron donors (acetate, lactate, or glucose) paired with ferrihydrite and sulfate as the electron acceptors and inoculated them with subsurface sediment as the microbial inoculum. Sulfate and ferrihydrite reduction occurred simultaneously and were faster with lactate than with acetate. 16S rRNA-based sequence analysis of the communities over time revealed that Desulfotomaculum was the major driver for sulfate reduction coupled with propionate oxidation in lactate-amended incubations. The reduction of sulfate resulted in sulfide production and subsequent abiotic reduction of ferrihydrite. In contrast, glucose promoted faster reduction of ferrihydrite, but without reduction of sulfate. Interestingly, the glucose-amended incubations led to two different biogeochemical trajectories among replicate bottles that resulted in distinct coloration (white and brown). The two outcomes in geochemical evolution might be due to the stochastic evolution of the microbial communities or subtle differences in the initial composition of the fermenting microbial community and its development via the use of different glucose fermentation pathways available within the community. Synchrotron-based x-ray analysis indicated that siderite and amorphous Fe(II) were formed in the replicate bottles with glucose, while ferrous sulfide and vivianite were formed with lactate or acetate. These data sets reveal that use of different C utilization pathways projects significant changes in microbial community composition over time that uniquely impact both the geochemistry and mineralogy of subsurface environments.

It's immoral, but I'd do it! Psychopathy traits affect decision-making in sacrificial dilemmas and in everyday moral situations.

PubMed

Pletti, Carolina; Lotto, Lorella; Buodo, Giulia; Sarlo, Michela

2017-05-01

This research investigated whether emotional hyporeactivity affects moral judgements and choices of action in sacrificial moral dilemmas and in everyday moral conflict situations in which harm to other's welfare is differentially involved. Twenty-six participants with high trait psychopathy (HP) and 25 with low trait psychopathy (LP) were selected based on the primary psychopathy scale of the Levenson Self-Report Psychopathy Scale. HP participants were more likely to sacrifice one person to save others in sacrificial dilemmas and to pursue a personal advantage in everyday moral situations entailing harm to another's good. While deciding in these situations, HP participants experienced lower unpleasantness as compared to LP participants. Conversely, no group differences emerged in choice of action and unpleasantness ratings for everyday moral situations that did not entail harm to others. Importantly, moral judgements did not differ in the two groups. These results suggest that high psychopathy trait affects choices of action in sacrificial dilemmas because of reduced emotional reactivity to harmful acts. The dissociation between choice of action and moral judgement suggests that the former is more closely related to emotional experience. Also, emotion seems to play a critical role in discriminating harmful from harmless acts and in driving decisions accordingly. © 2016 The British Psychological Society.

Spectrophotometric and spectroscopic studies of charge transfer complex of 1-Naphthylamine as an electron donor with picric acid as an electron acceptor in different polar solvents

NASA Astrophysics Data System (ADS)

Singh, Neeti; Ahmad, Afaq

2010-08-01

The charge transfer complex of 1-Naphthylamine as a donor with π-acceptor picric acid has been studied spectrophotometrically in different solvents at room temperature. The results indicate that the formation of charge transfer complex is high in less polar solvent. The stoichiometry of the complex was found to be 1:1 by straight line method. The data are analysed in terms of formation constant ( KCT), molar extinction coefficient ( ɛCT), standard free energy (Δ G o), oscillator strength ( ƒ), transition dipole moment ( μ EN), resonance energy ( R N) and ionization potential ( I D). It is concluded that the formation constant ( KCT) of the complex is found to be depends upon the nature of both electron acceptor and donor and also on the polarity of solvents. Further the charge transfer molecular complex between picric acid and 1-Naphthylamine is stabilized by hydrogen bonding.

Organic electronic devices with multiple solution-processed layers

DOEpatents

Forrest, Stephen R.; Lassiter, Brian E.; Zimmerman, Jeramy D.

2015-08-04

A method of fabricating a tandem organic photosensitive device involves depositing a first layer of an organic electron donor type material film by solution-processing of the organic electron donor type material dissolved in a first solvent; depositing a first layer of an organic electron acceptor type material over the first layer of the organic electron donor type material film by a dry deposition process; depositing a conductive layer over the interim stack by a dry deposition process; depositing a second layer of the organic electron donor type material over the conductive layer by solution-processing of the organic electron donor type material dissolved in a second solvent, wherein the organic electron acceptor type material and the conductive layer are insoluble in the second solvent; depositing a second layer of an organic electron acceptor type material over the second layer of the organic electron donor type material film by a dry deposition process, resulting in a stack.

Photosystem I from plants as a bacterial cytochrome P450 surrogate electron donor: terminal hydroxylation of branched hydrocarbon chains.

PubMed

Jensen, Kenneth; Johnston, Jonathan B; de Montellano, Paul R Ortiz; Møller, Birger Lindberg

2012-02-01

The ability of cytochrome P450 enzymes to catalyze highly regio- and stereospecific hydroxylations makes them attractive alternatives to approaches based on chemical synthesis but they require expensive cofactors, e.g. NAD(P)H, which limits their commercial potential. Ferredoxin (Fdx) is a multifunctional electron carrier that in plants accepts electrons from photosystem I (PSI) and facilitates photoreduction of NADP(+) to NADPH mediated by ferredoxin-NAD(P)H oxidoreductase (FdR). In bacteria, the electron flow is reversed and Fdx accepts electrons from NADPH via FdR and serves as the direct electron donor to bacterial P450s. By combining the two systems, we demonstrate that irradiation of PSI can drive the activity of a bacterial P450, CYP124 from Mycobacterium tuberculosis. The substitution of the costly cofactor NADPH with sunlight illustrates the potential of the light-driven hydroxylation system for biotechnology applications.

Enhancement of diffraction efficiency and storage life of poly(vinyl chloride)-based optical recording medium with incorporation of an electron donor

NASA Astrophysics Data System (ADS)

John, Beena Mary; Ushamani, M.; Sreekumar, K.; Joseph, Rani; Sudha Kartha, C.

2007-01-01

The diffraction efficiency, sensitivity, and storage life of methylene blue-sensitized poly(vinyl chloride) film was improved by the addition of an electron donor in the matrix. The addition of pyridine enhanced the diffraction efficiency by two times, and storage life of the gratings was increased to 2-3 days.

Electrical Manipulation of Donor Spin Qubits in Silicon and Germanium

NASA Astrophysics Data System (ADS)

Sigillito, Anthony James

Many proposals for quantum information devices rely on electronic or nuclear spins in semiconductors because of their long coherence times and compatibility with industrial fabrication processes. One of the most notable qubits is the electron spin bound to phosphorus donors in silicon, which offers coherence times exceeding seconds at low temperatures. These donors are naturally isolated from their environments to the extent that silicon has been coined a "semiconductor vacuum". While this makes for ultra-coherent qubits, it is difficult to couple two remote donors so quantum information proposals rely on high density arrays of qubits. Here, single qubit addressability becomes an issue. Ideally one would address individual qubits using electric fields which can be easily confined. Typically these schemes rely on tuning a donor spin qubit onto and off of resonance with a magnetic driving field. In this thesis, we measure the electrical tunability of phosphorus donors in silicon and use the extracted parameters to estimate the effects of electric-field noise on qubit coherence times. Our measurements show that donor ionization may set in before electron spins can be sufficiently tuned. We therefore explore two alternative options for qubit addressability. First, we demonstrate that nuclear spin qubits can be directly driven using electric fields instead of magnetic fields and show that this approach offers several advantages over magnetically driven spin resonance. In particular, spin transitions can occur at half the spin resonance frequency and double quantum transitions (magnetic-dipole forbidden) can occur. In a second approach to realizing tunable qubits in semiconductors, we explore the option of replacing silicon with germanium. We first measure the coherence and relaxation times for shallow donor spin qubits in natural and isotopically enriched germanium. We find that in isotopically enriched material, coherence times can exceed 1 ms and are limited by a

All-electric control of donor nuclear spin qubits in silicon

NASA Astrophysics Data System (ADS)

Sigillito, Anthony J.; Tyryshkin, Alexei M.; Schenkel, Thomas; Houck, Andrew A.; Lyon, Stephen A.

2017-10-01

The electronic and nuclear spin degrees of freedom of donor impurities in silicon form ultra-coherent two-level systems that are potentially useful for applications in quantum information and are intrinsically compatible with industrial semiconductor processing. However, because of their smaller gyromagnetic ratios, nuclear spins are more difficult to manipulate than electron spins and are often considered too slow for quantum information processing. Moreover, although alternating current magnetic fields are the most natural choice to drive spin transitions and implement quantum gates, they are difficult to confine spatially to the level of a single donor, thus requiring alternative approaches. In recent years, schemes for all-electrical control of donor spin qubits have been proposed but no experimental demonstrations have been reported yet. Here, we demonstrate a scalable all-electric method for controlling neutral 31P and 75As donor nuclear spins in silicon. Using coplanar photonic bandgap resonators, we drive Rabi oscillations on nuclear spins exclusively using electric fields by employing the donor-bound electron as a quantum transducer, much in the spirit of recent works with single-molecule magnets. The electric field confinement leads to major advantages such as low power requirements, higher qubit densities and faster gate times. Additionally, this approach makes it possible to drive nuclear spin qubits either at their resonance frequency or at its first subharmonic, thus reducing device bandwidth requirements. Double quantum transitions can be driven as well, providing easy access to the full computational manifold of our system and making it convenient to implement nuclear spin-based qudits using 75As donors.

SnO{sub 2} films: In-situ template-sacrificial growth and photovoltaic property based on SnO{sub 2}/poly(3-hexyl-thiophene) for hybrid solar cell

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

Zhang, Yange, E-mail: zhangygzhang@163.com; Li, Pinjiang; Xu, Xiaoyun

2015-10-15

Highlights: • SnO{sub 2} nanocrystals/thin films were fabricated on ITO glass substrate from preformed SnS thin film as sacrificial template. • The SnO{sub 2} film and SnO{sub 2}/P3HT was characterized by several techniques. • The new hybrid solar cell device was based on the hybrid thin film of SnO{sub 2} NCs and P3HT composites. - Abstract: we described a facile in-situ wet chemical method to prepare SnO{sub 2} thin film on ITO glass substrate from preformed SnS thin film as sacrificial template. The chemical conversion process of SnS to SnO{sub 2} was studied. The SnO{sub 2} film and SnO{sub 2}/P3HTmore » was characterized by several techniques, such as powder X-ray diffract meter (XRD), Raman spectrometer, scanning electron microscope (SEM), atomic force microscope (AFM) and UV–vis spectrophotometer in detail. The new SnO{sub 2}/P3HT hybrid solar cell device showed an open-circuit voltage of 0.185 V, a short-circuit current density of 0.366 mA/cm{sup 2} and a fill factor of 0.247, corresponding to a power conversion efficiency of 0.0167%.« less

Photocatalytic CO 2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO 2, CO, or Proton

DOE PAGES

Shimoda, Tomoe; Morishima, Takeshi; Kodama, Koichi; ...

2018-04-26

Trigonal-bipyramidal Co(II) complexes are used for photochemical carbon dioxide (CO 2) reduction with Ru(bpy) 3 2+ as a photosensitizer, tri-p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor to produce carbon monoxide and dihydrogen. Here, the CO 2 reduction is slow because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for reduction to catalytically active Co(0) by the photoproduced [Ru(bpy) 3] +.

Photocatalytic CO 2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO 2, CO, or Proton

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

Shimoda, Tomoe; Morishima, Takeshi; Kodama, Koichi

Trigonal-bipyramidal Co(II) complexes are used for photochemical carbon dioxide (CO 2) reduction with Ru(bpy) 3 2+ as a photosensitizer, tri-p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor to produce carbon monoxide and dihydrogen. Here, the CO 2 reduction is slow because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for reduction to catalytically active Co(0) by the photoproduced [Ru(bpy) 3] +.

On vibrational circular dichroism chirality transfer in electron donor-acceptor complexes: a prediction for the quinine···BF3 system.

PubMed

Rode, Joanna E; Jamróz, Michał H; Dobrowolski, Jan Cz; Sadlej, Joanna

2012-08-02

Vibrational circular dichroism (VCD) chirality transfer occurs when an achiral molecule interacts with a chiral one and becomes VCD-active. Unlike for H-bonds, for organic electron donor-acceptor (EDA) complexes this phenomenon remains almost unknown. Here, the VCD chirality transfer from chiral quinine to achiral BF3 is studied at the B3LYP/aug-cc-pVDZ level. Accessibility of four quinine electron donor sites changes with conformation. Therefore, the quinine conformational landscape was explored and a considerable agreement between X-ray and the most stable conformer geometries was achieved. The BF3 complex through the aliphatic quinuclidine N atom is definitely dominating and is predicted to be easily recognizable in the VCD spectrum. Out of several VCD chirality transfer modes, the ν(s)(BF3) mode, the most intense in the entire VCD spectrum, satisfies the VCD mode robustness criterion and can be used for monitoring the chirality transfer phenomenon in quinine···BF3 system.

High turnover in a photocatalytic system for water reduction to produce hydrogen using a Ru,  Rh,  Ru photoinitiated electron collector.

PubMed

Arachchige, Shamindri M; Shaw, Ryan; White, Travis A; Shenoy, Vimal; Tsui, Hei-Man; Brewer, Karen J

2011-04-18

Covalent coupling of Ru(II) light absorbers to a Rh(III) electron collecting site through polyazine bridging ligands affords photocatalytic production of H(2) in the presence of visible light and a sacrificial electron donor. A robust photocatalytic system displaying a high turnover of the photocatalyst has been developed using the photoinitiated electron collector [{(bpy)(2)Ru(dpp)}(2)RhBr(2)](5+) (bpy=2,2'-bipyridine; dpp=2,3-bis(2-pyridyl)pyrazine) and N,N-dimethylaniline in DMF/H(2)O. Studies have shown that increased [DMA], the headspace volume, and the use of DMF solvent improves the systems performance and stability providing mechanistic insight into the deactivation routes of the photocatalytic system. Photolysis of the system at 460 nm generates 20 mL of H(2) in 19.5 h with a maximum Φ=0.023 based on H(2) produced and an overall Φ=0.014 and 280 turnovers of the photocatalyst. The photocatalytic system also displays long-term photostability with 30 mL of H(2) generated and 420 turnovers in 50 h under the same conditions. Prolonged photolysis provides 820 mol H(2) per mole of catalyst. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mussel byssus-inspired engineering of synergistic nanointerfacial interactions as sacrificial bonds into carbon nanotube-reinforced soy protein/nanofibrillated cellulose nanocomposites: Versatile mechanical enhancement

NASA Astrophysics Data System (ADS)

Wang, Zhong; Zhao, Shujun; Kang, Haijiao; Zhang, Wei; Zhang, Shifeng; Li, Jianzhang

2018-03-01

Achieving flexible and stretchable biobased nanocomposites combining high strength and toughness is still a very challenging endeavor. Herein, we described a novel and versatile biomimetic design for tough and high-performance TEMPO-oxidized nanofibrillated cellulose (TONFC)/soy protein isolate (SPI) nanocomposites, which are triggered by catechol-mimetic carbon nanotubes (PCT) and iron ions (Fe(III)) to yield a strong yet sacrificial metal-ligand motifs into a chemically cross-linked architecture network. Taking advantage of self-polymerization of catechol-inspired natural tannic acid, PCT nanohybrid was prepared through adhering reactive poly-(tannic acid) (PTA) layer onto surfaces of carbon nanotubes via a simple dip-coating process. The high-functionality PCT induced the formation of the metal-ligand bonds through the ionic coordinates between the catechol groups in PCT and -COOH groups of TONFC skeleton with Fe(III) mediation that mimicked mussel byssus. Upon stretching, this tailored TONFC-Fe(III)-catechol coordination bonds served as sacrificial bonds that preferentially detach prior to the covalent network, which gave rise to efficient energy dissipation that the nanocomposites integrity was survived. As a result of these kind of synergistic interfacial interactions (sacrificial and covalent bonding), the optimal nanocomposite films processed high tensile strength (ca. 11.5 MPa), large elongation (ca. 79.3%), remarkable toughness (ca. 6.9 MJ m-3), and favorable water resistance as well as electrical conductivity. The proposed bioinspired strategy for designing plant protein-based materials enables control over their mechanical performance through the synergistic engineering of sacrificial bonds into the composite interface.

Failure modes of microstructured fibers with sacrificial bonds made by instability-assisted 3D printing

NASA Astrophysics Data System (ADS)

Zou, Shibo; Therriault, Daniel; Gosselin, Frederick

A simple modification by increasing the deposition height on a commercially available 3D printer makes it a mechanical sewing machine due to the fluid mechanical instability. A variety of stitches-like patterns can be produced, similar to those by the Newtonian fluid mechanical sewing machine\\x9D, but with more interesting characteristics in the additional third dimension, which creates weakly fused bonds in some patterns. With these bonds, the fabricated fibers exhibit improved toughness in uniaxial tensile test. The toughening mechanism is found to be similar to the one in spider silk - the breaking of sacrificial bonds and the releasing of hidden length contribute significant dissipated energy to the system. However, the mechanical performance of these microstructured fibers is restricted by early fiber breakage as the number of sacrificial bonds increases. Here, we seek to understand the failure mechanisms of the microstructured fibers through tensile tests and finite element simulations. Static and dynamic failure are both found to cause early fiber breakage. These findings are helpful for the design optimization of microstructured fibers with high toughness and ductility, which can find potential use in impact protection and safety-critical applications.

Scalable quantum computer architecture with coupled donor-quantum dot qubits

DOEpatents

Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

2014-08-26

A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

Sulfide as a Chemoautotrophic Electron Donor for Dissimilatory Arsenate Reduction in Mono Lake, California

NASA Astrophysics Data System (ADS)

Hoeft, S. E.; Kulp, T. R.; Stolz, J. S.; Oremland, R. S.

2003-12-01

In aqueous systems, arsenic occurs as arsenate [As(V)] or as arsenite [As(III)], with the latter form being more toxic and mobile. Mono Lake, California is a meromictic soda lake (pH = 9.8; salinity = 70-90 g/L) with exceptionally high arsenic content ( ˜200 μ M), a consequence of hydrothermal inputs combined with evaporative concentration. Previous work has shown that arsenic speciation changes from As(V) to the more reduced As(III) with vertical transition from the lake's surface oxic waters to its unmixed, anoxic bottom waters and that dissimilatory reduction is responsible for the observed change in arsenic speciation. Rates of in situ dissimilatory As(V) reduction measured by radiotracer ( ˜1- 6 μ mol/L/d) were estimated to be significant enough to mineralize up to 14% of annual primary productivity. Subsequent lab-based investigations with As(V)-amended ( ˜1-2 mM) bottom water displayed significantly higher rates (150-260 μ mol/L/d) of As(V) reduction and were not limited by the availability of organic electron donors such as acetate, lactate, malate and glucose. The focus of this study was to identify a natural source of electrons for As(V) reduction in Mono Lake. While Mono Lake contains plentiful dissolved organic carbon ( ˜7 mM) this material is usually refractory and resistant to bacterial oxidation. Alternatively, the anoxic bottom waters contain high concentrations of sulfide ions ( ˜1-2 mM) that could potentially serve as an electron donor for dissimilatory As(V) reduction. In a time course experiment with As(V)-amended Mono Lake bottom water, we observed oxidation of sulfide linked to the reduction of As(V) to As(III). This reaction did not occur in filter sterilized controls and sulfide loss did not occur in samples lacking As(V). In bottom water amended with additional sulfide (total = 6 mM) and As(V), we observed a linear relationship between rates of dissimilatory As(V) reduction and As(V) concentration. The highest rate observed under

New acceptor-bridge-donor strategy for enhancing NLO response with long-range excess electron transfer from the NH2...M/M3O donor (M = Li, Na, K) to inside the electron hole cage C20F19 acceptor through the unusual σ chain bridge (CH2)4.

PubMed

Bai, Yang; Zhou, Zhong-Jun; Wang, Jia-Jun; Li, Ying; Wu, Di; Chen, Wei; Li, Zhi-Ru; Sun, Chia-Chung

2013-04-04

Using the strong electron hole cage C20F19 acceptor, the NH2...M/M3O (M = Li, Na, and K) complicated donors with excess electron, and the unusual σ chain (CH2)4 bridge, we construct a new kind of electride molecular salt e(-)@C20F19-(CH2)4-NH2...M(+)/M3O(+) (M = Li, Na, and K) with excess electron anion inside the hole cage (to be encapsulated excess electron-hole pair) serving as a new A-B-D strategy for enhancing nonlinear optical (NLO) response. An interesting push-pull mechanism of excess electron generation and its long-range transfer is exhibited. The excess electron is pushed out from the (super)alkali atom M/M3O by the lone pair of NH2 in the donor and further pulled inside the hole cage C20F19 acceptor through the efficient long σ chain (CH2)4 bridge. Owing to the long-range electron transfer, the new designed electride molecular salts with the excess electron-hole pair exhibit large NLO response. For the e(-)@C20F19-(CH2)4-NH2...Na(+), its large first hyperpolarizability (β0) reaches up to 9.5 × 10(6) au, which is about 2.4 × 10(4) times the 400 au for the relative e(-)@C20F20...Na(+) without the extended chain (CH2)4-NH2. It is shown that the new strategy is considerably efficient in enhancing the NLO response for the salts. In addition, the effects of different bridges and alkali atomic number on β0 are also exhibited. Further, three modulating factors are found for enhancing NLO response. They are the σ chain bridge, bridge-end group with lone pair, and (super)alkali atom. The new knowledge may be significant for designing new NLO materials and electronic devices with electrons inside the cages. They may also be the basis of establishing potential organic chemistry with electron-hole pair.

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

Long-range electron transfer in zinc-phthalocyanine-oligo(phenylene-ethynylene)-based donor-bridge-acceptor dyads.

PubMed

Göransson, Erik; Boixel, Julien; Fortage, Jérôme; Jacquemin, Denis; Becker, Hans-Christian; Blart, Errol; Hammarström, Leif; Odobel, Fabrice

2012-11-05

In the context of long-range electron transfer for solar energy conversion, we present the synthesis, photophysical, and computational characterization of two new zinc(II) phthalocyanine oligophenylene-ethynylene based donor-bride-acceptor dyads: ZnPc-OPE-AuP(+) and ZnPc-OPE-C(60). A gold(III) porphyrin and a fullerene has been used as electron accepting moieties, and the results have been compared to a previously reported dyad with a tin(IV) dichloride porphyrin as the electron acceptor (Fortage et al. Chem. Commun. 2007, 4629). The results for ZnPc-OPE-AuP(+) indicate a remarkably strong electronic coupling over a distance of more than 3 nm. The electronic coupling is manifested in both the absorption spectrum and an ultrafast rate for photoinduced electron transfer (k(PET) = 1.0 × 10(12) s(-1)). The charge-shifted state in ZnPc-OPE-AuP(+) recombines with a relatively low rate (k(BET) = 1.0 × 10(9) s(-1)). In contrast, the rate for charge transfer in the other dyad, ZnPc-OPE-C(60), is relatively slow (k(PET) = 1.1 × 10(9) s(-1)), while the recombination is very fast (k(BET) ≈ 5 × 10(10) s(-1)). TD-DFT calculations support the hypothesis that the long-lived charge-shifted state of ZnPc-OPE-AuP(+) is due to relaxation of the reduced gold porphyrin from a porphyrin ring based reduction to a gold centered reduction. This is in contrast to the faster recombination in the tin(IV) porphyrin based system (k(BET) = 1.2 × 10(10) s(-1)), where the excess electron is instead delocalized over the porphyrin ring.

Visible light water splitting using dye-sensitized oxide semiconductors.

PubMed

Youngblood, W Justin; Lee, Seung-Hyun Anna; Maeda, Kazuhiko; Mallouk, Thomas E

2009-12-21

Researchers are intensively investigating photochemical water splitting as a means of converting solar to chemical energy in the form of fuels. Hydrogen is a key solar fuel because it can be used directly in combustion engines or fuel cells, or combined catalytically with CO(2) to make carbon containing fuels. Different approaches to solar water splitting include semiconductor particles as photocatalysts and photoelectrodes, molecular donor-acceptor systems linked to catalysts for hydrogen and oxygen evolution, and photovoltaic cells coupled directly or indirectly to electrocatalysts. Despite several decades of research, solar hydrogen generation is efficient only in systems that use expensive photovoltaic cells to power water electrolysis. Direct photocatalytic water splitting is a challenging problem because the reaction is thermodynamically uphill. Light absorption results in the formation of energetic charge-separated states in both molecular donor-acceptor systems and semiconductor particles. Unfortunately, energetically favorable charge recombination reactions tend to be much faster than the slow multielectron processes of water oxidation and reduction. Consequently, visible light water splitting has only recently been achieved in semiconductor-based photocatalytic systems and remains an inefficient process. This Account describes our approach to two problems in solar water splitting: the organization of molecules into assemblies that promote long-lived charge separation, and catalysis of the electrolysis reactions, in particular the four-electron oxidation of water. The building blocks of our artificial photosynthetic systems are wide band gap semiconductor particles, photosensitizer and electron relay molecules, and nanoparticle catalysts. We intercalate layered metal oxide semiconductors with metal nanoparticles. These intercalation compounds, when sensitized with [Ru(bpy)(3)](2+) derivatives, catalyze the photoproduction of hydrogen from sacrificial

Sacrificial-layer free transfer of mammalian cells using near infrared femtosecond laser pulses

PubMed Central

Zhang, Jun; Hartmann, Bastian; Siegel, Julian; Marchi, Gabriele; Clausen-Schaumann, Hauke; Sudhop, Stefanie; Huber, Heinz P.

2018-01-01

Laser-induced cell transfer has been developed in recent years for the flexible and gentle printing of cells. Because of the high transfer rates and the superior cell survival rates, this technique has great potential for tissue engineering applications. However, the fact that material from an inorganic sacrificial layer, which is required for laser energy absorption, is usually transferred to the printed target structure, constitutes a major drawback of laser based cell printing. Therefore alternative approaches using deep UV laser sources and protein based acceptor films for energy absorption, have been introduced. Nevertheless, deep UV radiation can introduce DNA double strand breaks, thereby imposing the risk of carcinogenesis. Here we present a method for the laser-induced transfer of hydrogels and mammalian cells, which neither requires any sacrificial material for energy absorption, nor the use of UV lasers. Instead, we focus a near infrared femtosecond (fs) laser pulse (λ = 1030 nm, 450 fs) directly underneath a thin cell layer, suspended on top of a hydrogel reservoir, to induce a rapidly expanding cavitation bubble in the gel, which generates a jet of material, transferring cells and hydrogel from the gel/cell reservoir to an acceptor stage. By controlling laser pulse energy, well-defined cell-laden droplets can be transferred with high spatial resolution. The transferred human (SCP1) and murine (B16F1) cells show high survival rates, and good cell viability. Time laps microscopy reveals unaffected cell behavior including normal cell proliferation. PMID:29718923

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.

Preferential inhibition of the plasma membrane NADH oxidase (NOX) activity by diphenyleneiodonium chloride with NADPH as donor

NASA Technical Reports Server (NTRS)

Morre, D. James

2002-01-01

The cell-surface NADH oxidase (NOX) protein of plant and animal cells will utilize both NADH and NADPH as reduced electron donors for activity. The two activities are distinguished by a differential inhibition by the redox inhibitor diphenyleneiodonium chloride (DPI). Using both plasma membranes and cells, activity with NADPH as donor was markedly inhibited by DPI at submicromolar concentrations, whereas with NADH as donor, DPI was much less effective or had no effect on the activity. The possibility of the inhibition being the result of two different enzymes was eliminated by the use of a recombinant NOX protein. The findings support the concept that NOX proteins serve as terminal oxidases for plasma membrane electron transport involving cytosolic reduced pyridine nucleotides as the natural electron donors and with molecular oxygen as the electron acceptor.

The role of amino acid electron-donor/acceptor atoms in host-cell binding peptides is associated with their 3D structure and HLA-binding capacity in sterile malarial immunity induction

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

Patarroyo, Manuel E., E-mail: mepatarr@mail.com; Universidad Nacional de Colombia, Bogota; Almonacid, Hannia

Highlights: Black-Right-Pointing-Pointer Fundamental residues located in some HABPs are associated with their 3D structure. Black-Right-Pointing-Pointer Electron-donor atoms present in {beta}-turn, random, distorted {alpha}-helix structures. Black-Right-Pointing-Pointer Electron-donor atoms bound to HLA-DR53. Black-Right-Pointing-Pointer Electron-acceptor atoms present in regular {alpha}-helix structure bound to HLA-DR52. -- Abstract: Plasmodium falciparum malaria continues being one of the parasitic diseases causing the highest worldwide mortality due to the parasite's multiple evasion mechanisms, such as immunological silence. Membrane and organelle proteins are used during invasion for interactions mediated by high binding ability peptides (HABPs); these have amino acids which establish hydrogen bonds between them in some of theirmore » critical binding residues. Immunisation assays in the Aotus model using HABPs whose critical residues had been modified have revealed a conformational change thereby enabling a protection-inducing response. This has improved fitting within HLA-DR{beta}1{sup Asterisk-Operator} molecules where amino acid electron-donor atoms present in {beta}-turn, random or distorted {alpha}-helix structures preferentially bound to HLA-DR53 molecules, whilst HABPs having amino acid electron-acceptor atoms present in regular {alpha}-helix structure bound to HLA-DR52. This data has great implications for vaccine development.« less

Evaluation of operating conditions for sustainable harvesting of microalgal biomass applying electrochemical method using non sacrificial electrodes.

PubMed

Misra, Rohit; Guldhe, Abhishek; Singh, Poonam; Rawat, Ismail; Stenström, Thor Axel; Bux, Faizal

2015-01-01

The efficient harvesting of microalgae is considered to be one of the challenging steps of algal biofuel production and a key factor limiting the commercial use of microalgae. To overcome the limitation of metallic electrodes depletion, the application of non-sacrificial electrode was investigated for the electrochemical harvesting (ECH) of microalgae. The effect of applied current, addition of electrolyte and initial pH were parameters investigated. The highest recovery efficiency of 83% was obtained for Scenedesmus obliquus at 1.5A, initial pH 9 and 6gL(-)(1) NaCl with power consumption of 3.84kWhkg(-)(1). Recovery efficiency of ECH process was comparable to literature reported centrifugation, filtration and chemical flocculation techniques but with a much lower power consumption. The ECH process with addition of electrolyte enhanced the lipid extraction by 22% without any adverse effects. The ECH process with non sacrificial carbon electrodes could be a possible harvesting step at commercial scale microalgal biomass production. Copyright © 2014 Elsevier Ltd. All rights reserved.

Donor ionization in size controlled silicon nanocrystals: The transition from defect passivation to free electron generation

NASA Astrophysics Data System (ADS)

Crowe, I. F.; Papachristodoulou, N.; Halsall, M. P.; Hylton, N. P.; Hulko, O.; Knights, A. P.; Yang, P.; Gwilliam, R. M.; Shah, M.; Kenyon, A. J.

2013-01-01

We studied the photoluminescence spectra of silicon and phosphorus co-implanted silica thin films on (100) silicon substrates as a function of isothermal annealing time. The rapid phase segregation, formation, and growth dynamics of intrinsic silicon nanocrystals are observed, in the first 600 s of rapid thermal processing, using dark field mode X-TEM. For short annealing times, when the nanocrystal size distribution exhibits a relatively small mean diameter, formation in the presence of phosphorus yields an increase in the luminescence intensity and a blue shift in the emission peak compared with intrinsic nanocrystals. As the mean size increases with annealing time, this enhancement rapidly diminishes and the peak energy shifts further to the red than the intrinsic nanocrystals. These results indicate the existence of competing pathways for the donor electron, which depends strongly on the nanocrystal size. In samples containing a large density of relatively small nanocrystals, the tendency of phosphorus to accumulate at the nanocrystal-oxide interface means that ionization results in a passivation of dangling bond (Pb-centre) type defects, through a charge compensation mechanism. As the size distribution evolves with isothermal annealing, the density of large nanocrystals increases at the expense of smaller nanocrystals, through an Ostwald ripening mechanism, and the majority of phosphorus atoms occupy substitutional lattice sites within the nanocrystals. As a consequence of the smaller band-gap, ionization of phosphorus donors at these sites increases the free carrier concentration and opens up an efficient, non-radiative de-excitation route for photo-generated electrons via Auger recombination. This effect is exacerbated by an enhanced diffusion in phosphorus doped glasses, which accelerates silicon nanocrystal growth.

Effect of sacrificial agents on the dispersion of metal cocatalysts for photocatalytic hydrogen evolution

NASA Astrophysics Data System (ADS)

Cao, Shaowen; Shen, Baojia; Huang, Qian; Chen, Zhe

2018-06-01

Surface photodeposition of noble metal cocatalyst has been regarded as an effective approach to facilitate the separation of charge carriers and reduce the over-potential of water reduction, thus to enhance the photocatalytic H2-production activities of semiconductor photocatalyst. Herein, the influences of sacrificial agents used in the photodeposition process on the dispersion of noble metal nanoparticles are investigated, via a series of technique of photocatalytic hydrogen evolution test, microstructure analysis and photoelectrochemical measurement. As a result, the sacrificial agents are found to show large impact on the loading amount, particle size and distribution of different metals on the surface of g-C3N4. The real loading amount of Pt and Au is higher in methanol solution than that in triethanolamine solution. Better distribution and smaller size of Pt nanoparticles are achieved in the presence of methanol; while better distribution and smaller size of Au nanoparticles are achieved in the presence of triethanolamine. As a result, quite different charge transfer ability is achieved for the synthesized Pt and Au decorated g-C3N4, which subsequently leads to disparate photocatalytic activities of the same g-C3N4 photocatalyst under various conditions. The finding in this work indicates that the valid deposition content, particle size and distribution of metal cocatalysts should be carefully taken into account when comparing the photocatalytic activities among various samples.

Synthesis, and spectroscopic studies of charge transfer complex of 1,2-dimethylimidazole as an electron donor with π-acceptor 2,4-dinitro-1-naphthol in different polar solvents

NASA Astrophysics Data System (ADS)

Miyan, Lal; Khan, Ishaat M.; Ahmad, Afaq

2015-07-01

The charge transfer (CT) complex of 1,2-dimethylimidazole (DMI) as an electron donor with π acceptor 2,4-dinitro-1-naphthol (DNN) has been studied spectrophotometrically in different solvents like chloroform, acetonitrile, methanol, methylene chloride, etc. at room temperature. The CT complex which is formed through the transfer of lone pair electrons from DMI to DNN exhibits well resolved CT bands and the regions of these bands were remarkably different from those of the donor and acceptor. The stoichiometry of the CT complex was found to be 1:1 by a straight-line method between donor and acceptor with maximum absorption bands. The novel CT complex has been characterized by FTIR, TGA-DTA, powder XRD, 1H NMR and 13C NMR spectroscopic techniques. The Benesi-Hildebrand equation has been used to determine the formation constant (KCT), molar extinction coefficient (εCT), standard gibbs free energy (ΔG°) and other physical parameters of the CT complex. The formation constant recorded higher values and molar extinction coefficient recorded lower values in chloroform compared with methylene chloride, methanol and acetonitrile, confirming the strong interaction between the molecular orbital's of donor and acceptor in the ground state in less polar solvent. This CT complex has been studied by absorption spectra of donor 1,2-dimethylimidazole (DMI) and acceptor 2,4-dinitro-1-naphthol (DNN) by using the spectrophotometric technique in various solvents at room temperature.

Rational Design of High-Performance Wide-Bandgap (≈2 eV) Polymer Semiconductors as Electron Donors in Organic Photovoltaics Exhibiting High Open Circuit Voltages (≈1 V).

PubMed

Chochos, Christos L; Katsouras, Athanasios; Gasparini, Nicola; Koulogiannis, Chrysanthos; Ameri, Tayebeh; Brabec, Christoph J; Avgeropoulos, Apostolos

2017-01-01

Systematic optimization of the chemical structure of wide-bandgap (≈2.0 eV) "donor-acceptor" copolymers consisting of indacenodithiophene or indacenodithieno[3,2-b]thiophene as the electron-rich unit and thieno[3,4-c]pyrrole-4,6-dione as the electron-deficient moiety in terms of alkyl side chain engineering and distance of the electron-rich and electron-deficient monomers within the repeat unit of the polymer chain results in high-performance electron donor materials for organic photovoltaics. Specifically, preliminary results demonstrate extremely high open circuit voltages (V oc s) of ≈1.0 V, reasonable short circuit current density (J sc ) of around 11 mA cm -2 , and moderate fill factors resulting in efficiencies close to 6%. All the devices are fabricated in an inverted architecture with the photoactive layer processed by doctor blade equipment, showing the compatibility with roll-to-roll large-scale manufacturing processes. From the correlation of the chemical structure-optoelectronic properties-photovoltaic performance, a rational guide toward further optimization of the chemical structure in this family of copolymers, has been achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rationalizing the photophysical properties of BODIPY laser dyes via aromaticity and electron-donor-based structural perturbations

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

Waddell, Paul G.; Liu, Xiaogang; Zhao, Teng

2015-05-01

The absorption and fluorescence properties of six boron dipyrromethene (BODIPY) laser dyes with simple non-aromatic substituents are rationalized by relating them to observable structural perturbations within the molecules of the dyes. An empirical relationship involving the structure and the optical properties is derived using a combination of single-crystal X-ray diffraction data, quantum chemical calculations and electronic constants: i.e. the tendency of the pyrrole bond lengths towards aromaticity and the UV-vis absorption and fluorescence wavelengths correlating with the electron-donor properties of the substituents. The effect of molecular conformation on the solid-state optical properties of the dyes is also discussed. The findingsmore » in this study also demonstrate the usefulness and limitations of using crystal structure data to develop structure-property relationships in this class of optical materials, contributing to the growing effort to design optoelectronic materials with tunable properties via molecular engineering.« less

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.

On chirality transfer in electron donor-acceptor complexes. A prediction for the sulfinimine···BF3 system.

PubMed

Rode, Joanna E; Dobrowolski, Jan Cz

2012-01-01

Stabilization energies of the electron donor-acceptor sulfinimine···BF(3) complexes calculated at either the B3LYP/aug-cc-pVTZ or the MP2/aug-cc-pVTZ level do not allow to judge, whether the N- or O-atom in sulfinimine is stronger electron-donor to BF(3) . The problem seems to be solvable because chirality transfer phenomenon between chiral sulfinimine and achiral BF(3) is expected to be vibrational circular dichroism (VCD) active. Moreover, the bands associated with the achiral BF(3) molecule are predicted to be the most intense in the entire spectrum. However, the VCD band robustness analyses show that most of the chirality transfer modes of BF(3) are unreliable. Conversely, variation of VCD intensity with change of intermolecular distance, angle, and selected dihedrals between the complex partners shows that to establish the robustness of chirality transfer mode. It is also necessary to determine the influence of the potential energy surface (PES) shape on the VCD intensity. At the moment, there is still no universal criterion for the chirality transfer mode robustness and the conclusions formulated based on one system cannot be directly transferred even to a quite similar one. However, it is certain that more attention should be focused on relation of PES shape and the VCD mode robustness problem. Copyright © 2011 Wiley Periodicals, Inc.

Impact of Thermal Annealing on Organic Photovoltaic Cells Using Regioisomeric Donor-Acceptor-Acceptor Molecules.

PubMed

Zhang, Tao; Han, Han; Zou, Yunlong; Lee, Ying-Chi; Oshima, Hiroya; Wong, Ken-Tsung; Holmes, Russell J

2017-08-02

We report a promising set of donor-acceptor-acceptor (D-A-A) electron-donor materials based on coplanar thieno[3,2-b]/[2,3-b]indole, benzo[c][1,2,5]thiadiazole, and dicyanovinylene, which are found to show broadband absorption with high extinction coefficients. The role of the regioisomeric electron-donating thienoindole moiety on the physical and structural properties is examined. Bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) based on the thieno[2,3-b]indole-based electron donor NTU-2, using C 70 as an electron acceptor, show a champion power conversion efficiency of 5.2% under AM 1.5G solar simulated illumination. This efficiency is limited by a low fill factor (FF), as has previously been the case in D-A-A systems. In order to identify the origin of the limited FF, further insight into donor layer charge-transport behavior is realized by examining planar heterojunction OPVs, with emphasis on the evolution of film morphology with thermal annealing. Compared to as-deposited OPVs that exhibit insufficient donor crystallinity, crystalline OPVs based on annealed thin films show an increase in the short-circuit current density, FF, and power conversion efficiency. These results suggest that that the crystallization of D-A-A molecules might not be realized spontaneously at room temperature and that further processing is needed to realize efficient charge transport in these materials.

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.

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

PubMed Central

Dumée, Ludovic F.; She, Fenghua; Duke, Mikel; Gray, Stephen; Hodgson, Peter; Kong, Lingxue

2014-01-01

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm) as well as the sintering pressure (5–20 ton·m−2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested. PMID:28344241

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.

Coenzyme preference of Streptococcus pyogenes δ1-pyrroline-5-carboxylate reductase: evidence supporting NADPH as the physiological electron donor.

PubMed

Petrollino, Davide; Forlani, Giuseppe

2012-07-01

The streptococcal enzyme that catalyzes the last step in proline biosynthesis was heterologously expressed and the recombinant protein was purified to electrophoretic homogeneity and characterized thoroughly. As for δ1-pyrroline-5-carboxylate reductases from other sources, it was able to use either NADH or NADPH as the electron donor in vitro. However, with NADH the activity was markedly inhibited by physiological levels of NADP+. Results also strengthen the possibility that an unusual ordered substrate binding occurs, in which the dinucleotide binds last.

Synthesis and Characterization of Organic Dyes Containing Various Donors and Acceptors

PubMed Central

Wu, Tzi-Yi; Tsao, Ming-Hsiu; Chen, Fu-Lin; Su, Shyh-Gang; Chang, Cheng-Wen; Wang, Hong-Paul; Lin, Yuan-Chung; Ou-Yang, Wen-Chung; Sun, I-Wen

2010-01-01

New organic dyes comprising carbazole, iminodibenzyl, or phenothiazine moieties, respectively, as the electron donors, and cyanoacetic acid or acrylic acid moieties as the electron acceptors/anchoring groups were synthesized and characterized. The influence of heteroatoms on carbazole, iminodibenzyl and phenothiazine donors, and cyano-substitution on the acid acceptor is evidenced by spectral, electrochemical, photovoltaic experiments, and density functional theory calculations. The phenothiazine dyes show solar-energy-to-electricity conversion efficiency (η) of 3.46–5.53%, whereas carbazole and iminodibenzyl dyes show η of 2.43% and 3.49%, respectively. PMID:20162019

Spectral engineering in π-conjugated polymers with intramolecular donor-acceptor interactions.

PubMed

Beaujuge, Pierre M; Amb, Chad M; Reynolds, John R

2010-11-16

With the development of light-harvesting organic materials for solar cell applications and molecular systems with fine-tuned colors for nonemissive electrochromic devices (e.g., smart windows, e-papers), a number of technical challenges remain to be overcome. Over the years, the concept of "spectral engineering" (tailoring the complex interplay between molecular physics and the various optical phenomena occurring across the electromagnetic spectrum) has become increasingly relevant in the field of π-conjugated organic polymers. Within the spectral engineering toolbox, the "donor-acceptor" approach uses alternating electron-rich and electron-deficient moieties along a π-conjugated backbone. This approach has proved especially valuable in the synthesis of dual-band and broadly absorbing chromophores with useful photovoltaic and electrochromic properties. In this Account, we highlight and provide insight into a present controversy surrounding the origin of the dual band of absorption sometimes encountered in semiconducting polymers structured using the "donor-acceptor" approach. Based on empirical evidence, we provide some schematic representations to describe the possible mechanisms governing the evolution of the two-band spectral absorption observed on varying the relative composition of electron-rich and electron-deficient substituents along the π-conjugated backbone. In parallel, we draw attention to the choice of the method employed to estimate and compare the absorption coefficients of polymer chromophores exhibiting distinct repeat unit lengths, and containing various extents of solubilizing side-chains along their backbone. Finally, we discuss the common assumption that "donor-acceptor" systems should have systematically lower absorption coefficients than their "all-donor" counterparts. The proposed models point toward important theoretical parameters which could be further explored at the macromolecular level to help researchers take full advantage of the

Perylene-Diimide Based Donor-Acceptor-Donor Type Small-Molecule Acceptors for Solution-Processable Organic Solar Cells

NASA Astrophysics Data System (ADS)

Ganesamoorthy, Ramasamy; Vijayaraghavan, Rajagopalan; Sakthivel, Pachagounder

2017-12-01

Development of nonfullerene acceptors plays an important role in the commercial availability of plastic solar cells. We report herein synthesis of bay-substituted donor-acceptor-donor (D-A-D)-type perylene diimide (PDI)-based small molecules (SM-1 to SM-4) by Suzuki coupling method and their use as acceptors in bulk heterojunction organic solar cells (BHJ-OSCs) with poly(3-hexylthiophene) (P3HT) polymer donor. We varied the number of electron-rich thiophene units and the solubilizing side chains and also evaluated the optical and electrochemical properties of the small molecules. The synthesized small molecules were confirmed by Fourier-transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and high-resolution mass spectroscopy (HR-MS). The small molecules showed extensive and strong absorption in the ultraviolet-visible (UV-Vis) region up to 750 nm, with bandgap (E_{{g}}^{{opt}} ) reduced below <2 eV. The energy levels of small molecules SM-1 to SM-4 were suitable for use as electron-accepting materials. The small molecules showed good thermal stability up to 300°C. BHJ-OSCs with SM-1 and P3HT polymer donor showed maximum power conversion efficiency (PCE) of 0.19% with V oc of 0.30 V, J sc of 1.72 mA cm-2, and fill factor (FF) of 37%. The PCE decreased with the number of thiophene units. The PCE of SM-2 was lower than that of SM-1. This difference in PCE can be explained by the higher aggregation tendency of the bithiophene compared with the thiophene unit. Introduction of the solubilizing group in the bay position increased the aggregation property, leading to much lower PCE than for the small molecules without solubilizing group.

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.

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.

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.

The diheme cytochrome c4 from Vibrio cholerae is a natural electron donor to the respiratory cbb3 oxygen reductase

PubMed Central

Chang, Hsin-Yang; Ahn, Young; Pace, Laura A.; Lin, Myat T.; Lin, Yun-Hui; Gennis, Robert B.

2010-01-01

The respiratory chain of Vibrio cholerae contains three bd-type quinol oxygen reductases as well as one cbb3 oxygen reductase. The cbb3 oxygen reductase has been previously isolated and characterized, however the natural mobile electron donor(s) which shuttles electrons between the bc1 complex and the cbb3 oxygen reductase is not known. The most likely candidates are the diheme cytochrome c4 and mono-heme cytochrome c5, which have been previously shown to be present in the periplasm of aerobically grown cultures of V. cholerae. Both cytochromes c4 and c5 from V. cholerae have been cloned and expressed heterologously in E. coli. It is shown that reduced cytochrome c4 is a substrate for the purified cbb3 oxygen reductase and can support steady state oxygen reductase activity of at least 300 e−1/s. In contrast, reduced cytochrome c5 is not a good substrate for the cbb3 oxygen reductase. Surprisingly, the dependence of the oxygen reductase activity on the concentration of cytochrome c4 does not exhibit saturation. Global spectroscopic analysis of the time course of the oxidation of cytochrome c4 indicates that the apparent lack of saturation is due to the strong dependence of KM and Vmax on the concentration of oxidized cytochrome c4. Whether this is an artifact of the in vitro assay or has physiological significance remains unknown. Cyclic voltammetry was used to determine that the midpoint potentials of the two hemes in cytochrome c4 are 240 mV and 340 mV (vs SHE), similar to the electrochemical properties of other c4-type cytochromes. Genomic analysis shows a strong correlation between the presence of a c4-type cytochrome and a cbb3 oxygen reductase within the β- and γ- proteobacterial clades, suggesting that cytochrome c4 is the likely natural electron donor to the cbb3 oxygen reductases within these organisms. These would include the β-proteobacteria Neisseria meningitidis and Neisseria gonnorhoeae, in which the cbb3 oxygen reductases are the only terminal

Radio frequency reflectometry and charge sensing of a precision placed donor in silicon

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

Hile, Samuel J., E-mail: samhile@gmail.com; House, Matthew G.; Peretz, Eldad

2015-08-31

We compare charge transitions on a deterministic single P donor in silicon using radio frequency reflectometry measurements with a tunnel coupled reservoir and DC charge sensing using a capacitively coupled single electron transistor (SET). By measuring the conductance through the SET and comparing this with the phase shift of the reflected radio frequency (RF) excitation from the reservoir, we can discriminate between charge transfer within the SET channel and tunneling between the donor and reservoir. The RF measurement allows observation of donor electron transitions at every charge degeneracy point in contrast to the SET conductance signal where charge transitions aremore » only observed at triple points. The tunnel coupled reservoir has the advantage of a large effective lever arm (∼35%), allowing us to independently extract a neutral donor charging energy ∼62 ± 17 meV. These results demonstrate that we can replace three terminal transistors by a single terminal dispersive reservoir, promising for high bandwidth scalable donor control and readout.« less

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

Two-Electron Transfer Pathways.

PubMed

Lin, Jiaxing; Balamurugan, D; Zhang, Peng; Skourtis, Spiros S; Beratan, David N

2015-06-18

The frontiers of electron-transfer chemistry demand that we develop theoretical frameworks to describe the delivery of multiple electrons, atoms, and ions in molecular systems. When electrons move over long distances through high barriers, where the probability for thermal population of oxidized or reduced bridge-localized states is very small, the electrons will tunnel from the donor (D) to acceptor (A), facilitated by bridge-mediated superexchange interactions. If the stable donor and acceptor redox states on D and A differ by two electrons, it is possible that the electrons will propagate coherently from D to A. While structure-function relations for single-electron superexchange in molecules are well established, strategies to manipulate the coherent flow of multiple electrons are largely unknown. In contrast to one-electron superexchange, two-electron superexchange involves both one- and two-electron virtual intermediate states, the number of virtual intermediates increases very rapidly with system size, and multiple classes of pathways interfere with one another. In the study described here, we developed simple superexchange models for two-electron transfer. We explored how the bridge structure and energetics influence multielectron superexchange, and we compared two-electron superexchange interactions to single-electron superexchange. Multielectron superexchange introduces interference between singly and doubly oxidized (or reduced) bridge virtual states, so that even simple linear donor-bridge-acceptor systems have pathway topologies that resemble those seen for one-electron superexchange through bridges with multiple parallel pathways. The simple model systems studied here exhibit a richness that is amenable to experimental exploration by manipulating the multiple pathways, pathway crosstalk, and changes in the number of donor and acceptor species. The features that emerge from these studies may assist in developing new strategies to deliver multiple

Recalcitrant Carbonaceous Material: A Source of Electron Donors for Anaerobic Microbial Metabolisms in the Subsurface?

NASA Astrophysics Data System (ADS)

Nixon, S. L.; Montgomery, W.; Sephton, M. A.; Cockell, C. S.

2014-12-01

More than 90% of organic material on Earth resides in sedimentary rocks in the form of kerogens; fossilized organic matter formed through selective preservation of high molecular weight biopolymers under anoxic conditions. Despite its prevalence in the subsurface, the extent to which this material supports microbial metabolisms is unknown. Whilst aerobic microorganisms are known to derive energy from kerogens within shales, utilization in anaerobic microbial metabolisms that proliferate in the terrestrial subsurface, such as microbial iron reduction, has yet to be demonstrated. Data are presented from microbial growth experiments in which kerogens and shales were supplied as the sole electron donor source for microbial iron reduction by an enrichment culture. Four well-characterized kerogens samples (representative of Types I-IV, classified by starting material), and two shale samples, were assessed. Organic analysis was carried out to investigate major compound classes present in each starting material. Parallel experiments were conducted to test inhibition of microbial iron reduction in the presence of each material when the culture was supplied with a full redox couple. The results demonstrate that iron-reducing microorganisms in this culture were unable to use kerogens and shales as a source of electron donors for energy acquisition, despite the presence of compound classes known to support this metabolism. Furthermore, the presence of these materials was found to inhibit microbial iron reduction to varying degrees, with some samples leading to complete inhibition. These results suggest that recalcitrant carbonaceous material in the terrestrial subsurface is not available for microbial iron reduction and similar metabolisms, such as sulphate-reduction. Further research is needed to investigate the inhibition exerted by these materials, and to assess whether these findings apply to other microbial consortia. These results may have significant implications for

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

Do thermal donors reduce the lifetimes of Czochralski-grown silicon crystals?

NASA Astrophysics Data System (ADS)

Miyamura, Y.; Harada, H.; Nakano, S.; Nishizawa, S.; Kakimoto, K.

2018-05-01

High-performance electronics require long carrier lifetimes within their silicon crystals. This paper reports the effects of thermal donors on the lifetimes of carriers in as-grown n-type silicon crystals grown by the Czochralski method. We grew silicon crystals with two different concentrations of thermal donors using the following two cooling processes: one was cooled with a 4-h halt after detaching the crystal from the melt, and the other was cooled continuously. The crystal grown with the cooling halt contained higher concentrations of thermal donors of the order of 1 × 1013 cm-3, while the crystal without the halt had no thermal donors. The measured bulk lifetimes were in the range of 15-18 ms. We concluded that thermal donors in Czochralski-grown silicon crystals do not act to reduce their lifetimes.

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.

Tuning the Electronic Structure of Fe(II) Polypyridines via Donor Atom and Ligand Scaffold Modifications: A Computational Study.

PubMed

Bowman, David N; Bondarev, Alexey; Mukherjee, Sriparna; Jakubikova, Elena

2015-09-08

Fe(II) polypyridines are an important class of pseudo-octahedral metal complexes known for their potential applications in molecular electronic switches, data storage and display devices, sensors, and dye-sensitized solar cells. Fe(II) polypyridines have a d(6) electronic configuration and pseudo-octahedral geometry and can therefore possess either a high-spin (quintet) or a low-spin (singlet) ground state. In this study, we investigate a series of complexes based on [Fe(tpy)2](2+) (tpy = 2,2';6',2″-terpyridine) and [Fe(dcpp)2](2+) (dcpp = 2,6-bis(2-carboxypyridyl)pyridine). The ligand field strength in these complexes is systematically tuned by replacing the central pyridine with five-membered (N-heterocyclic carbene, pyrrole, furan) or six-membered (aryl, thiazine-1,1-dioxide, 4-pyrone) moieties. To determine the impact of ligand substitutions on the relative energies of metal-centered states, the singlet, triplet, and quintet states of the Fe(II) complexes were optimized in water (PCM) using density functional theory at the B3LYP+D2 level with 6-311G* (nonmetals) and SDD (Fe) basis sets. It was found that the dcpp ligand scaffold allows for a more ideal octahedral coordination environment in comparison to the tpy ligand scaffold. The presence of six-membered central rings also allows for a more ideally octahedral coordination environment relative to five-membered central rings, regardless of the ligand scaffold. We find that the ligand field strength in the Fe(II) polypyridines can be tuned by altering the donor atom identity, with C donor atoms providing the strongest ligand field.

Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals.

PubMed

Gupta, Deeksha; Sarker, Bivas; Thadikaran, Keith; John, Vijay; Maldarelli, Charles; John, George

2015-06-01

Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as "chemical herder" is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air-sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice.

Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals

PubMed Central

Gupta, Deeksha; Sarker, Bivas; Thadikaran, Keith; John, Vijay; Maldarelli, Charles; John, George

2015-01-01

Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as “chemical herder” is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air–sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice. PMID:26601197

Standardization of transfusion practice in organ donors using the Digital Intern, an electronic decision support algorithm.

PubMed

Connor, Joseph P; Cunningham, Ashley M; Raife, Thomas; Rose, William N; Medow, Joshua E

2017-06-01

Prospective clinical trials support restrictive thresholds for red blood cell (RBC) transfusion. Nonsurvivable donors are a major source of organs for transplantation. The Digital Intern (DI) is a computer algorithm to standardize donor care that includes a more restrictive transfusion threshold. The impact of standardized and restrictive RBC transfusion in organ donors, as determined by the DI, has not been reported. We conducted a retrospective cohort study to compare the transfusion practice of the DI (n = 100) to a historic group of physician-managed donors (n = 90). Transfusion rates, the number of units transfused, and pretransfusion laboratory values were compared between groups. The variability of these parameters was also compared between groups. Finally, the number of transplanted organs per donor in each group was compared. The mean time as a donor was 25.9 ± 15.2 hours and was not different between the groups. In the DI group 19% were transfused compared to 26% in the control group (p = 0.3). The number of units transfused was less in the DI group (1 unit vs. 2 units per transfusion, p = 0.03) and the pretransfusion hematocrit was lower in the DI group (23% vs. 27%, p = 0.01). The variability in the latter two parameters was significantly lower in the DI group. The number of transplanted organs per donor was similar in both groups (3.24 [DI] vs. 3.03 [control], p = 0.37). The DI provides a more standardization transfusion practice in organ donors and reduces blood use without compromising transplantable organs. © 2017 AABB.

Surface code architecture for donors and dots in silicon with imprecise and nonuniform qubit couplings

DOE PAGES

Pica, G.; Lovett, B. W.; Bhatt, R. N.; ...

2016-01-14

A scaled quantum computer with donor spins in silicon would benefit from a viable semiconductor framework and a strong inherent decoupling of the qubits from the noisy environment. Coupling neighboring spins via the natural exchange interaction according to current designs requires gate control structures with extremely small length scales. In this work, we present a silicon architecture where bismuth donors with long coherence times are coupled to electrons that can shuttle between adjacent quantum dots, thus relaxing the pitch requirements and allowing space between donors for classical control devices. An adiabatic SWAP operation within each donor/dot pair solves the scalabilitymore » issues intrinsic to exchange-based two-qubit gates, as it does not rely on subnanometer precision in donor placement and is robust against noise in the control fields. In conclusion, we use this SWAP together with well established global microwave Rabi pulses and parallel electron shuttling to construct a surface code that needs minimal, feasible local control.« less

Fluorinated arene, imide and unsaturated pyrrolidinone based donor acceptor conjugated polymers: Synthesis, structure-property and device studies

NASA Astrophysics Data System (ADS)

Liyanage, Arawwawala Don Thilanga

After the discovery of doped polyacetylene, organic semiconductor materials are widely studied as high impending active components in consumer electronics. They have received substantial consideration due to their potential for structural tailoring, low cost, large area and mechanically flexible alternatives to common inorganic semiconductors. To acquire maximum use of these materials, it is essential to get a strong idea about their chemical and physical nature. Material chemist has an enormous role to play in this novel area, including development of efficient synthetic methodologies and control the molecular self-assembly and (opto)-electronic properties. The body of this thesis mainly focuses on the substituent effects: how different substituents affect the (opto)-electronic properties of the donor-acceptor (D-A) conjugated polymers. The main priority goes to understand, how different alkyl substituent effect to the polymer solubility, crystallinity, thermal properties (e.g.: glass transition temperature) and morphological order. Three classes of D-A systems were extensively studied in this work. The second chapter mainly focuses on the synthesis and structure-property study of fluorinated arene (TFB) base polymers. Here we used commercially available 1,4-dibromo-2,3,5,6-tetrafluorobenzene (TFB) as the acceptor material and prepare several polymers using 3,3'-dialkyl(3,3'-R2T2) or 3,3'-dialkoxy bithiophene (3,3'-RO2T2) units as electron donors. A detail study was done using 3,3'-bithiophene donor units incorporating branched alkoxy-functionalities by systematic variation of branching position and chain length. The study allowed disentangling the branching effects on (i) aggregation tendency, intermolecular arrangement, (iii) solid state optical energy gaps, and (iv) electronic properties in an overall consistent picture, which might guide future polymer synthesis towards optimized materials for opto-electronic applications. The third chapter mainly focused on

Antibacterial activity of microstructured sacrificial anode thin films by combination of silver with platinum group elements (platinum, palladium, iridium).

PubMed

Köller, Manfred; Bellova, Petri; Javid, Siyamak Memar; Motemani, Yahya; Khare, Chinmay; Sengstock, Christina; Tschulik, Kristina; Schildhauer, Thomas A; Ludwig, Alfred

2017-05-01

Five different Ag dots arrays (16 to 400dots/mm 2 ) were fabricated on a continuous platinum, palladium, or iridium thin film and for comparison also on titanium film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Staphylococcus aureus (S. aureus) were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards S. aureus was induced by Ag dot arrays on each of the platinum group thin film (sacrificial anode system for Ag) in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag). Among platinum group elements the Ir-Ag system exerted the highest antibacterial activity which was accompanied by most advanced dissolution of the Ag dots and Ag ion release compared to Ag dots on Pt or Pd. Copyright © 2016 Elsevier B.V. All rights reserved.

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

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

Correlation of Hydrogen-Atom Abstraction Reaction Efficiencies for Aryl Radicals with their Vertical Electron Affinities and the Vertical Ionization Energies of the Hydrogen Atom Donors

PubMed Central

Jing, Linhong; Nash, John J.

2009-01-01

The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer (FT – ICR). Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropanol, were measured for twenty-three structurally different, positively-charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for three of the aryl radicals with isopropanol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of several different hydrogen-atom donors with a few selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X – H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of twenty-nine different aryl radicals and eighteen different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state as the energy difference between the neutral and ionic reactants decreases. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be “tuned” by structural changes that influence either

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.

Donor-derived infections among Chinese donation after cardiac death liver recipients.

PubMed

Ye, Qi-Fa; Zhou, Wei; Wan, Qi-Quan

2017-08-21

To investigate blood cultures of deceased donors and report the confirmed transmission of bacterial infection from donors to liver recipients. We retrospectively studied the results of blood cultures among our donation after cardiac death (DCD) donors and calculated the donor-derived bacterial infection rates among liver recipients. Study participants underwent liver transplantation between January 1, 2010 and February 1, 2017. The study involved a total of 67 recipients of liver grafts from 67 DCD donors. We extracted the data of donors' and patients' characteristics, culture results and clinical outcomes, especially the post-transplant complications in liver recipients, from electronic medical records. We analyzed the characteristics of the donors and the corresponding liver recipients with emphasis put on donor-derived infections. Head trauma was the most common origin of death among our 67 DCD donors (46.3%). Blood taken prior to the procurement operation was cultured for 53 of the donors, with 17 episodes of bloodstream infections developing from 13 donors. The predominant organism isolated from the blood of donors was Gram-positive bacteria (70.6%). Only three (4.5%) of 67 liver recipients developed confirmed donor-derived bacterial infections, with two isolates of multidrug-resistant Klebsiella pneumoniae and one isolate of multidrug-resistant Enterobacter aerogenes. The liver recipients with donor-derived infections showed relation to higher crude mortality and graft loss rates (33.3% each) within 3 mo post transplantation, as compared to those without donor-derived infections (9.4% and 4.7%, respectively). All three liver recipients received appropriate antimicrobial therapy. Liver recipients have high occurrence of donor-derived infections. The liver recipients with donor-derived multidrug-resistant Enterobacteriaceae infections can have good outcome if appropriate antimicrobial therapy is given.

On the origin of red and blue shifts of X-H and C-H stretching vibrations in formic acid (formate ion) and proton donor complexes.

PubMed

Tâme Parreira, Renato Luis; Galembeck, Sérgio Emanuel; Hobza, Pavel

2007-01-08

Complexes between formic acid or formate anion and various proton donors (HF, H(2)O, NH(3), and CH(4)) are studied by the MP2 and B3LYP methods with the 6-311++G(3df,3pd) basis set. Formation of a complex is characterized by electron-density transfer from electron donor to ligands. This transfer is much larger with the formate anion, for which it exceeds 0.1 e. Electron-density transfer from electron lone pairs of the electron donor is directed into sigma* antibonding orbitals of X--H bonds of the electron acceptor and leads to elongation of the bond and a red shift of the X--H stretching frequency (standard H-bonding). However, pronounced electron-density transfer from electron lone pairs of the electron donor also leads to reorganization of the electron density in the electron donor, which results in changes in geometry and vibrational frequency. These changes are largest for the C--H bonds of formic acid and formate anion, which do not participate in H-bonding. The resulting blue shift of this stretching frequency is substantial and amounts to almost 35 and 170 cm(-1), respectively.

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.

Organic Donor-Acceptor Complexes as Novel Organic Semiconductors.

PubMed

Zhang, Jing; Xu, Wei; Sheng, Peng; Zhao, Guangyao; Zhu, Daoben

2017-07-18

Organic donor-acceptor (DA) complexes have attracted wide attention in recent decades, resulting in the rapid development of organic binary system electronics. The design and synthesis of organic DA complexes with a variety of component structures have mainly focused on metallicity (or even superconductivity), emission, or ferroelectricity studies. Further efforts have been made in high-performance electronic investigations. The chemical versatility of organic semiconductors provides DA complexes with a great number of possibilities for semiconducting applications. Organic DA complexes extend the semiconductor family and promote charge separation and transport in organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). In OFETs, the organic complex serves as an active layer across extraordinary charge pathways, ensuring the efficient transport of induced charges. Although an increasing number of organic semiconductors have been reported to exhibit good p- or n-type properties (mobilities higher than 1 or even 10 cm 2 V -1 s -1 ), critical scientific challenges remain in utilizing the advantages of existing semiconductor materials for more and wider applications while maintaining less complicated synthetic or device fabrication processes. DA complex materials have revealed new insight: their unique molecular packing and structure-property relationships. The combination of donors and acceptors could offer practical advantages compared with their unimolecular materials. First, growing crystals of DA complexes with densely packed structures will reduce impurities and traps from the self-assembly process. Second, complexes based on the original structural components could form superior mixture stacking, which can facilitate charge transport depending on the driving force in the coassembly process. Third, the effective use of organic semiconductors can lead to tunable band structures, allowing the operation mode (p- or n-type) of the transistor to be

Methods for the synthesis of donor-acceptor cyclopropanes

NASA Astrophysics Data System (ADS)

Tomilov, Yu V.; Menchikov, L. G.; Novikov, R. A.; Ivanova, O. A.; Trushkov, I. V.

2018-03-01

The interest in cyclopropane derivatives is caused by the facts that, first, the three-carbon ring is present in quite a few natural and biologically active compounds and, second, compounds with this ring are convenient building blocks for the synthesis of diverse molecules (acyclic, alicyclic and heterocyclic). The carbon–carbon bonds in cyclopropane are kinetically rather inert; hence, they need to be activated to be involved in reactions. An efficient way of activation is to introduce vicinal electron-donating and electron-withdrawing substituents into the ring; these substrates are usually referred to as donor-acceptor cyclopropanes. This review gives a systematic account of the key methods for the synthesis of donor-acceptor cyclopropanes. The most important among them are reactions of nucleophilic alkenes with diazo compounds and iodonium ylides and approaches based on reactions of electrophilic alkenes with sulfur ylides (the Corey–Chaykovsky reaction). Among other methods used for this purpose, noteworthy are cycloalkylation of CH-acids, addition of α-halocarbonyl compounds to alkenes, cyclization via 1,3-elimination, reactions of alkenes with halocarbenes followed by reduction, the Simmons–Smith reaction and some other. The scope of applicability and prospects of various methods for the synthesis of donor-acceptor cyclopropanes are discussed. The bibliography includes 530 references.

Donor-derived infections among Chinese donation after cardiac death liver recipients

PubMed Central

Ye, Qi-Fa; Zhou, Wei; Wan, Qi-Quan

2017-01-01

AIM To investigate blood cultures of deceased donors and report the confirmed transmission of bacterial infection from donors to liver recipients. METHODS We retrospectively studied the results of blood cultures among our donation after cardiac death (DCD) donors and calculated the donor-derived bacterial infection rates among liver recipients. Study participants underwent liver transplantation between January 1, 2010 and February 1, 2017. The study involved a total of 67 recipients of liver grafts from 67 DCD donors. We extracted the data of donors’ and patients’ characteristics, culture results and clinical outcomes, especially the post-transplant complications in liver recipients, from electronic medical records. We analyzed the characteristics of the donors and the corresponding liver recipients with emphasis put on donor-derived infections. RESULTS Head trauma was the most common origin of death among our 67 DCD donors (46.3%). Blood taken prior to the procurement operation was cultured for 53 of the donors, with 17 episodes of bloodstream infections developing from 13 donors. The predominant organism isolated from the blood of donors was Gram-positive bacteria (70.6%). Only three (4.5%) of 67 liver recipients developed confirmed donor-derived bacterial infections, with two isolates of multidrug-resistant Klebsiella pneumoniae and one isolate of multidrug-resistant Enterobacter aerogenes. The liver recipients with donor-derived infections showed relation to higher crude mortality and graft loss rates (33.3% each) within 3 mo post transplantation, as compared to those without donor-derived infections (9.4% and 4.7%, respectively). All three liver recipients received appropriate antimicrobial therapy. CONCLUSION Liver recipients have high occurrence of donor-derived infections. The liver recipients with donor-derived multidrug-resistant Enterobacteriaceae infections can have good outcome if appropriate antimicrobial therapy is given. PMID:28883707

Fabrication of Covalently Crosslinked and Amine-Reactive Microcapsules by Reactive Layer-by-Layer Assembly of Azlactone-Containing Polymer Multilayers on Sacrificial Microparticle Templates

PubMed Central

Saurer, Eric M.; Flessner, Ryan M.; Buck, Maren E.; Lynn, David M.

2011-01-01

We report on the fabrication of covalently crosslinked and amine-reactive hollow microcapsules using ‘reactive’ layer-by-layer assembly to deposit thin polymer films on sacrificial microparticle templates. Our approach is based on the alternating deposition of layers of a synthetic polyamine and a polymer containing reactive azlactone functionality. Multilayered films composed of branched poly(ethylene imine) (BPEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) were fabricated layer-by-layer on the surfaces of calcium carbonate and glass microparticle templates. After fabrication, these films contained residual azlactone functionality that was accessible for reaction with amine-containing molecules. Dissolution of the calcium carbonate or glass cores using aqueous ethylenediamine tetraacetic acid (EDTA) or hydrofluoric acid (HF), respectively, led to the formation of hollow polymer microcapsules. These microcapsules were robust enough to encapsulate and retain a model macromolecule (FITC-dextran) and were stable for at least 22 hours in high ionic strength environments, in low and high pH solutions, and in several common organic solvents. Significant differences in the behaviors of capsules fabricated on CaCO3 and glass cores were observed and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Whereas capsules fabricated on CaCO3 templates collapsed upon drying, capsules fabricated on glass templates remained rigid and spherical. Characterization using EDS suggested that this latter behavior results, at least in part, from the presence of insoluble metal fluoride salts that are trapped or precipitate within the walls of capsules after etching of the glass cores using HF. Our results demonstrate that the assembly of BPEI/PVDMA films on sacrificial templates can be used to fabricate reactive microcapsules of potential use in a wide range of fields, including catalysis, drug and gene delivery, imaging, and

An ultrafast spectroscopic and quantum mechanical investigation of multiple emissions in push-pull pyridinium derivatives bearing different electron donors.

PubMed

Carlotti, B; Benassi, E; Cesaretti, A; Fortuna, C G; Spalletti, A; Barone, V; Elisei, F

2015-08-28

A joint experimental and theoretical approach, involving state-of-the-art femtosecond fluorescence up-conversion measurements and quantum mechanical computations including vibronic effects, was employed to get a deep insight into the excited state dynamics of two cationic dipolar chromophores (Donor-π-Acceptor(+)) where the electron deficient portion is a N-methyl pyridinium and the electron donor a trimethoxyphenyl or a pyrene, respectively. The ultrafast spectroscopic investigation, and the time resolved area normalised emission spectra in particular, revealed a peculiar multiple emissive behaviour and allowed the distinct emitting states to be remarkably distinguished from solvation dynamics, occurring in water in a similar timescale. The two and three emissions experimentally detected for the trimethoxyphenyl and pyrene derivatives, respectively, were associated with specific local emissive minima in the potential energy surface of S1 on the ground of quantum-mechanical calculations. A low polar and planar Locally Excited (LE) state together with a highly polar and Twisted Intramolecular Charge Transfer (TICT) state is identified to be responsible for the dual emission of the trimethoxyphenyl compound. Interestingly, the more complex photobehaviour of the pyrenyl derivative was explained considering the contribution to the fluorescence coming not only from the LE and TICT states but also from a nearly Planar Intramolecular Charge Transfer (PICT) state, with both the TICT and the PICT generated from LE by progressive torsion around the quasi-single bond between the methylpyridinium and the ethene bridge. These findings point to an interconversion between rotamers for the pyrene compound taking place in its excited state against the Non-equilibrated Excited Rotamers (NEER) principle.

Electron Bifurcation: Thermodynamics and Kinetics of Two-Electron Brokering in Biological Redox Chemistry

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

Zhang, Peng; Yuly, Jonathon L.; Lubner, Carolyn E.

How can proteins drive two electrons from a redox active donor onto two acceptors at very different potentials and distances? And how can this transaction be conducted without dissipating very much energy or violating the laws of thermodynamics? Nature appears to have addressed these challenges by coupling thermodynamically uphill and downhill electron transfer reactions, using two-electron donor cofactors that have very different potentials for the removal of the first and second electron. Although electron bifurcation is carried out with near perfection from the standpoint of energy conservation and electron delivery yields, it is a biological energy transduction paradigm that hasmore » only come into focus recently. This Account provides an exegesis of the biophysical principles that underpin electron bifurcation.« less

Defining donor and acceptor strength in conjugated copolymers

NASA Astrophysics Data System (ADS)

Hedström, Svante; Wang, Ergang; Persson, Petter

2017-03-01

The progress in efficiency of organic photovoltaic devices is largely driven by the development of new donor-acceptor (D-A) copolymers. The number of possible D-A combinations escalates rapidly with the ever-increasing number of donor and acceptor units, and the design process often involves a trial-and-error approach. We here present a computationally efficient methodology for the prediction of optical and electronic properties of D-A copolymers based on density functional theory calculations of donor- and acceptor-only homopolymers. Ten donors and eight acceptors are studied, as well as all of their 80 D-A copolymer combinations, showing absorption energies of 1.3-2.3 eV, and absorption strengths varying by up to a factor of 2.5. Focus lies on exhibited trends in frontier orbital energies, optical band gaps, and absorption intensities, as well as their relation to the molecular structure. Based on the results, we define the concept of donor and acceptor strength, and calculate this quantity for all investigated units. The light-harvesting capabilities of the 80 D-A copolymers were also assessed. This gives a valuable theoretical guideline to the design of D-A copolymers with the potential to reduce the synthesis efforts in the development of new polymers.

Ultrafast Electron Transfer across a Nanocapsular Wall: Coumarins as Donors, Viologen as Acceptor, and Octa Acid Capsule as the Mediator.

PubMed

Chuang, Chi-Hung; Porel, Mintu; Choudhury, Rajib; Burda, Clemens; Ramamurthy, V

2018-01-11

Results of our study on ultrafast electron transfer (eT) dynamics from coumarins (coumarin-1, coumarin-480, and coumarin-153) incarcerated within octa acid (OA) capsules as electron donors to methyl viologen dissolved in water as acceptor are presented. Upon photoexcitation, coumarin inside the OA capsule transfers an electron to the acceptor electrostatically attached to the capsule leading to a long-lived radical-ion pair separated by the OA capsular wall. This charge-separated state returns to the neutral ground state via back electron transfer on the nanosecond time scale. This system allows for ultrafast electron transfer processes through a molecular wall from the apolar capsular interior to the highly polar (aqueous) environment on the femtosecond time scale. Employing femtosecond transient absorption spectroscopy, distinct rates of both forward (1-25 ps) and backward eT (700-1200 ps) processes were measured. Further understanding of the energetics is provided using Rehm-Weller analysis for the investigated photoinduced eT reactions. The results provide the rates of the eT across a molecular wall, akin to an isotropic solution, depending on the standard free energy of the reaction. The insights from this work could be utilized in the future design of efficient electron transfer processes across interfaces separating apolar and polar environments.

Towards Sustainable H2 Production: Rational Design of Hydrophobic Triphenylamine-based Dyes for Sensitized Ethanol Photoreforming.

PubMed

Dessì, Alessio; Monai, Matteo; Bessi, Matteo; Montini, Tiziano; Calamante, Massimo; Mordini, Alessandro; Reginato, Gianna; Trono, Cosimo; Fornasiero, Paolo; Zani, Lorenzo

2018-02-22

Donor-acceptor dyes are a well-established class of photosensitizers, used to enhance visible-light harvesting in solar cells and in direct photocatalytic reactions, such as H 2 production by photoreforming of sacrificial electron donors (SEDs). Amines-typically triethanolamine (TEOA)-are commonly employed as SEDs in such reactions. Dye-sensitized photoreforming of more sustainable, biomass-derived alcohols, on the other hand, was only recently reported by using methanol as the electron donor. In this work, several rationally designed donor-acceptor dyes were used as sensitizers in H 2 photocatalytic production, comparing the efficiency of TEOA and EtOH as SEDs. In particular, the effect of hydrophobic chains in the spacer and/or the donor unit of the dyes was systematically studied. The H 2 production rates were higher when TEOA was used as SED, whereas the activity trends depended on the SED used. The best performance was obtained with TEOA by using a sensitizer with just one bulky hydrophobic moiety, propylenedioxythiophene, placed on the spacer unit. In the case of EtOH, the best-performing sensitizers were the ones featuring a thiazolo[5,4-d]thiazole internal unit, needed for enhancing light harvesting, and carrying alkyl chains on both the donor part and the spacer unit. The results are discussed in terms of reaction mechanism, interaction with the SED, and structural/electrochemical properties of the sensitizers. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Linear Hyperfine Tuning of Donor Spins in Silicon Using Hydrostatic Strain

NASA Astrophysics Data System (ADS)

Mansir, J.; Conti, P.; Zeng, Z.; Pla, J. J.; Bertet, P.; Swift, M. W.; Van de Walle, C. G.; Thewalt, M. L. W.; Sklenard, B.; Niquet, Y. M.; Morton, J. J. L.

2018-04-01

We experimentally study the coupling of group V donor spins in silicon to mechanical strain, and measure strain-induced frequency shifts that are linear in strain, in contrast to the quadratic dependence predicted by the valley repopulation model (VRM), and therefore orders of magnitude greater than that predicted by the VRM for small strains |ɛ |<10-5. Through both tight-binding and first principles calculations we find that these shifts arise from a linear tuning of the donor hyperfine interaction term by the hydrostatic component of strain and achieve semiquantitative agreement with the experimental values. Our results provide a framework for making quantitative predictions of donor spins in silicon nanostructures, such as those being used to develop silicon-based quantum processors and memories. The strong spin-strain coupling we measure (up to 150 GHz per strain, for Bi donors in Si) offers a method for donor spin tuning—shifting Bi donor electron spins by over a linewidth with a hydrostatic strain of order 10-6—as well as opportunities for coupling to mechanical resonators.

Cell-Free Synthetic Biology Chassis for Nanocatalytic Photon-to-Hydrogen Conversion

DOE PAGES

Wang, Peng; Chang, Angela Y.; Novosad, Valentyn; ...

2017-06-11

We report on entirely man-made nanobio hybrid fabricated through assembly of cell-free expressed transmembrane proton pump and semiconductor nanoparticles as an efficient nanocatalysis for photocatalytic H 2 evolution. The system produces H 2 at a turnover rate of 239 (μmole protein) -1 h -1 under green and 17742 (μmole protein) -1 h -1 under white light at ambient conditions, in water at neutral pH with methanol as a sacrificial electron donor. Robustness and flexibility of this approach allows for systemic manipulation at nanoparticle-bio interface toward directed evolution of energy transformation materials and artificial systems.

Cell-Free Synthetic Biology Chassis for Nanocatalytic Photon-to-Hydrogen Conversion

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

Wang, Peng; Chang, Angela Y.; Novosad, Valentyn

We report on entirely man-made nanobio hybrid fabricated through assembly of cell-free expressed transmembrane proton pump and semiconductor nanoparticles as an efficient nanocatalysis for photocatalytic H 2 evolution. The system produces H 2 at a turnover rate of 239 (μmole protein) -1 h -1 under green and 17742 (μmole protein) -1 h -1 under white light at ambient conditions, in water at neutral pH with methanol as a sacrificial electron donor. Robustness and flexibility of this approach allows for systemic manipulation at nanoparticle-bio interface toward directed evolution of energy transformation materials and artificial systems.

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.

Transport Measurements on Si Nanostructures with Counted Sb Donors

NASA Astrophysics Data System (ADS)

Singh, Meenakshi; Bielejec, Edward; Garratt, Elias; Ten Eyck, Gregory; Bishop, Nathaniel; Wendt, Joel; Luhman, Dwight; Carroll, Malcolm; Lilly, Michael

2014-03-01

Donor based spin qubits are a promising platform for quantum computing. Single qubits using timed implant of donors have been demonstrated.1 Extending this to multiple qubits requires precise control over the placement and number of donors. Such control can be achieved by using a combination of low-energy heavy-ion implants (to reduce depth straggle), electron-beam lithography (to define position), focused ion beam (to localize implants to one lithographic site) and counting the number of implants with a single ion detector.2 We report transport measurements on MOS quantum dots implanted with 5, 10 and 20 Sb donors using the approach described above. A donor charge transition is identified by a charge offset in the transport characteristics. Correlation between the number of donors and the charge offsets is studied. These results are necessary first steps towards fabricating donor nanostructures for two qubit interactions. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. The work was supported by Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000. 1J. J. Pla et al., Nature 496, 334 (2013) 2J. A. Seamons et al., APL 93, 043124 (2008).

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.

Investigation of sacrificial layer and building block for layered nanofabrication (LNF)

NASA Astrophysics Data System (ADS)

Shih, Ting-Yu

Layered Nanoscale Fabrication (LNF) is a "bottom-up" procedure that uses multiple layers to build 3-dimensional nanoscale structures. Here, in this dissertation, several candidates for sacrificial layers were explored, The thermal stability of gold nanoparticles and simple patterns are also reported. In order to obtain information on layer thickness and film quality; the samples were characterized using atomic force microscopy (AFM) and ellipsometry. Octadecyltrichlorosilane (OTS) was first investigated for use as a sacrificial layer and we studied filth growth by targeted self-replication of silane multilayers with and without the presence of thiolated gold nanoparticles on silicon oxide substrates. The particles adhered to the substrate during layer grafting. The film grew selectively on the substrate, without covering the particles. AFM was used to investigate the growth mechanism and the process of embedding the nanoparticles. OTS multilayer films up to 9 layers were grown in a linear, bilayer-by bilayer mode, free of islands and defects. We also report on studies of monolayer and multilayer formation of Methyl-11-dimethylmonochlorosilyl-undecanoate films. Flat multilayers up to 3-layers thick were grown. AFM was used to measure the height of an observable "edge" of the multilayer film and this provides and independent determination of the MOSUD layer height of 1.5 nm: However, the particles detached from the surface when we attempted to grow multilayer. One strategy of linking the particles to form 2D arrays, thermal activation in ambient air, was investigated. The morphological properties of flaked nanoparticles and structures on silicon oxide substrates before and after heating were characterized by using AFM. For widely separated 5 nm gold nanoparticles height decreased over 50% at 600 °C. Further heating to 630 °C caused most particles to completely disappear, with small amount of particle residue left on the surface. Particles positioned near to other

Gender Disparity in Living-Donor Kidney Transplant Among Minority Ethnic Groups.

PubMed

Peracha, Javeria; Hayer, Manvir Kaur; Sharif, Adnan

2016-04-01

We have limited data on gender disparities between living kidney transplant donors and recipients across ethnic groups. This was a retrospective cohort study of all living-donor kidney transplants performed at a single center in an ethnically diverse region of England. Data were extracted from the United Kingdom National Transplant Database and University Hospitals Birmingham electronic medical records. We analyzed 713 living-donor kidney transplant procedures that were performed from 1987 to 2014. Gender disparities were observed, with women more likely to be living donors (54.7%) and less likely to be recipients (39.4%). Most male recipients received kidneys from female donors versus male donors (70.2% vs 29.8%), whereas the proportion of men receiving kidneys from women (50.9%) and from men (49.1%) were similar (P < .001). Black, Asian, and donors from other minority groups comprised 18.7% of the donor cohort. South Asian partner-to-partner transplants (n = 22) were predominantly men receiving transplants from women (90.9%) versus women receiving transplants from men (9.1%; P = .003). Male patients more commonly donated their kidney to children than to women (10.2% vs 6.4%; P = .046). South Asian donations to children were similar between males and females; however, boys exclusively received kidneys from male donors (8/8) versus from female donors (8/12). Gender disparity exists in living-donor kidney transplant, with disparities more pronounced in some ethnic groups and among particular relationships. This finding requires targeted counseling and research to understand whether the cause is medical or sociocultural obstacles.

Distinguishing between Dexter and rapid sequential electron transfer in covalently linked donor-acceptor assemblies.

PubMed

Soler, Monica; McCusker, James K

2008-04-09

with the lack of enhanced emission at temperatures below the glass-to-fluid transition of the solvent and the absence of visible absorption features associated with the Mn(II)2 core allows for a definitive assignment of Dexter transfer as the dominant excited-state reaction pathway. A similar conclusion was reached for complex 3 based in part on the smaller driving force for electron transfer (DeltaG0(ET) = -0.1 eV), the increase in probability of Dexter transfer due to the closer proximity of the donor excited state to the dimanganese acceptor, and a lack of emission from the compound upon formation of an optical glass at 80 K. Electronic coupling constants for Dexter transfer were determined to be approximately 10 cm(-1) and approximately 0.15 cm(-1) in complexes 3 and 4, respectively, indicating that the change in spatial localization of the excited state from the bridge (complex 3) to the periphery of the chromophore (complex 4) results in a decrease in electronic coupling to the dimanganese core of nearly 2 orders of magnitude. In addition to providing insight into the influence of donor/acceptor proximity on exchange energy transfer, this study underscores the utility of variable-temperature measurements in cases where Dexter and electron-transfer mechanisms can lead to indistinguishable spectroscopic observables.

Trehalose protects Mn-depleted photosystem 2 preparations against the donor-side photoinhibition.

PubMed

Yanykin, D V; Khorobrykh, A A; Mamedov, M D; Klimov, V V

2016-11-01

Recently, it has been shown that the addition of 1M trehalose leads to the increase of the rate of oxygen photoconsumption associated with activation of electron transport in the reaction center of photosystem 2 (PS2) in Mn-depleted PS2 membranes (apo-WOC-PS2) [37]. In the present work the effect of trehalose on photoinhibition of apo-WOC-PS2 preparations (which are characterized by a high sensitivity to the donor side photoinhibition of PS2) was investigated. The degree of photoinhibition was estimated by the loss of the capability of exogenous electron donor (sodium ascorbate) to reactivate the electron transport (measured by light-induced changes of chlorophyll fluorescence yield (∆F)) in apo-WOC-PS2. It was found that 1M trehalose enhanced the Mn 2+ -dependent suppression of photoinhibition of apo-WOC-PS2: in the presence of trehalose the addition of 0.2μM Mn 2+ (corresponding to 2 Mn 2+ per one reaction center) was sufficient for an almost complete suppression of the donor side photoinhibition of the complex. In the absence of trehalose it was necessary to add 100μM Mn 2+ to achieve a similar result. The effect of trehalose was observed during photoinhibition of apo-WOC-PS2 at low (15μmolphotons -1 m -2 ) and high (200μmolphotons -1 m -2 ) light intensity. When Mn 2+ was replaced by other PS2 electron donors (ferrocyanide, DPC) as well as by Ca 2+ the protective effect of trehalose was not observed. It was also found that 1M trehalose decreased photoinhibition of apo-WOC-PS2 if the samples contained endogenous manganese (1-2 Mn ions per one RC was enough for the maximum protection effect). It is concluded that structural changes in PS2 caused by the addition of trehalose enhance the capability of photochemical reaction centers of apo-WOC-PS2 to accept electrons from manganese (both exogenous and endogenous), which in turn leads to a considerable suppression of the donor side photoinhibition of PS2. Copyright © 2016 Elsevier B.V. All rights reserved.

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

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.

Experimental confirmation of the predicted shallow donor hydrogen state in zinc oxide.

PubMed

Cox, S F; Davis, E A; Cottrell, S P; King, P J; Lord, J S; Gil, J M; Alberto, H V; Vilão, R C; Piroto Duarte, J; Ayres de Campos, N; Weidinger, A; Lichti, R L; Irvine, S J

2001-03-19

We confirm the recent prediction that interstitial protium may act as a shallow donor in zinc oxide, by direct spectroscopic observation of its muonium counterpart. On implantation into ZnO, positive muons--chemically analogous to protons in this context--form paramagnetic centers below about 40 K. The muon-electron contact hyperfine interaction, as well as the temperature and activation energy for ionization, imply a shallow level. Similar results for the cadmium chalcogenides suggest that such shallow donor states are generic to the II-VI compounds. The donor level depths should serve as a guide for the electrical activity of interstitial hydrogen.

Improvement of photovoltaic performance by substituent effect of donor and acceptor structure of TPA-based dye-sensitized solar cells.

PubMed

Inostroza, Natalia; Mendizabal, Fernando; Arratia-Pérez, Ramiro; Orellana, Carlos; Linares-Flores, Cristian

2016-01-01

We report a computational study of a series of organic dyes built with triphenylamine (TPA) as an electron donor group. We designed a set of six dyes called (TPA-n, where n = 0-5). In order to enhance the electron-injection process, the electron-donor effect of some specific substituent was studied. Thus, we gave insights into the rational design of organic TPA-based chromophores for use in dye-sensitized solar cells (DSSCs). In addition, we report the HOMO, LUMO, the calculated excited state oxidized potential E(dye*)(eV) and the free energy change for electron-injection ΔGinject(eV), and the UV-visible absorption bands for TPA-n dyes by a time-dependent density functional theory (TDDFT) procedure at the B3LYP and CAM-B3LYP levels with solvent effect. The results demonstrate that the introduction of the electron-acceptor groups produces an intramolecular charge transfer showing a shift of the absorption wavelengths of TPA-n under studies. Graphical Abstract Several organic dyes TPA-n with different donors and acceptors are modeled. A strong conjugation acrros the donor and anchoring groips (TPA-n) bas been studied. Candidate TPA-3 shows a promising results.

Photoinduced electron transfer in covalent ruthenium-anthraquinone dyads: relative importance of driving-force, solvent polarity, and donor-bridge energy gap.

PubMed

Hankache, Jihane; Wenger, Oliver S

2012-02-28

Four rigid rod-like molecules comprised of a Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) photosensitizer, a 9,10-anthraquinone electron acceptor, and a molecular bridge connecting the two redox partners were synthesized and investigated by optical spectroscopic and electrochemical means. An attempt was made to assess the relative importance of driving-force, solvent polarity, and bridge variation on the rates of photoinduced electron transfer in these molecules. Expectedly, introduction of tert-butyl substituents in the bipyridine ligands of the ruthenium complex and a change in solvent from dichloromethane to acetonitrile lead to a significant acceleration of charge transfer rates. In dichloromethane, photoinduced electron transfer is not competitive with the inherent excited-state deactivation processes of the photosensitizer. In acetonitrile, an increase in driving-force by 0.2 eV through attachment of tert-butyl substituents to the bpy ancillary ligands causes an increase in electron transfer rates by an order of magnitude. Replacement of a p-xylene bridge by a p-dimethoxybenzene spacer entails an acceleration of charge transfer rates by a factor of 3.5. In the dyads from this study, the relative order of importance of individual influences on electron transfer rates is therefore as follows: solvent polarity ≥ driving-force > donor-bridge energy gap.

Reduction of electron accumulation at InN(0001) surfaces via saturation of surface states by potassium and oxygen as donor- or acceptor-type adsorbates

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

Eisenhardt, A.; Reiß, S.; Krischok, S., E-mail: stefan.krischok@tu-ilmenau.de

2014-01-28

The influence of selected donor- and acceptor-type adsorbates on the electronic properties of InN(0001) surfaces is investigated implementing in-situ photoelectron spectroscopy. The changes in work function, surface band alignment, and chemical bond configurations are characterized during deposition of potassium and exposure to oxygen. Although an expected opponent charge transfer characteristic is observed with potassium donating its free electron to InN, while dissociated oxygen species extract partial charge from the substrate, a reduction of the surface electron accumulation occurs in both cases. This observation can be explained by adsorbate-induced saturation of free dangling bonds at the InN resulting in the disappearancemore » of surface states, which initially pin the Fermi level and induce downward band bending.« less

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.

Diketopyrrolopyrrole-based π-bridged donor-acceptor polymer for photovoltaic applications.

PubMed

Li, Wenting; Lee, Taegweon; Oh, Soong Ju; Kagan, Cherie R

2011-10-01

We report the synthesis, properties, and photovoltaic applications of a new conjugated copolymer (C12DPP-π-BT) containing a donor group (bithiophene) and an acceptor group (2,5-didodecylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione), bridged by a phenyl group. Using cyclic voltammetry, we found the energy levels of C12DPP-π-BT are intermediate to common electron donor and acceptor photovoltaic materials, poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), respectively. Whereas P3HT and PCBM are exclusively electron donating or accepting, we predict C12DPP-π-BT may uniquely serve as either an electron donor or an acceptor when paired with PCBM or P3HT forming junctions with large built-in potentials. We confirmed the ambipolar nature of C12DPP-π-BT in space charge limited current measurements and in C12DPP-π-BT:PCBM and C12DPP-π-BT:P3HT bulk heterojunction solar cells, achieving power conversion efficiencies of 1.67% and 0.84%, respectively, under illumination of AM 1.5G (100 mW/cm(2)). Adding diiodooctane to C12DPP-π-BT:PCBM improved donor-acceptor inter-mixing and film uniformity, and therefore enhanced charge separation and overall device efficiency. Using higher-molecular-weight polymer C12DPP-π-BT in both C12DPP-π-BT:PCBM and C12DPP-π-BT:P3HT devices improved charge transport and hence the performance of the solar cells. In addition, we compared the structural and electronic properties of C12DPP-π-BT:PCBM and C12DPP-π-BT:P3HT blends, representing the materials classes of polymer:fullerene and polymer:polymer blends. In C12DPP-π-BT:PCBM blends, higher short circuit currents were obtained, consistent with faster charge transfer and balanced electron and hole transport, but lower open circuit voltages may be reduced by trap-assisted recombination and interfacial recombination losses. In contrast, C12DPP-π-BT:P3HT blends exhibit higher open circuit voltage, but short circuit currents were limited by charge transfer

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.

Donor impurity incorporation during layer growth of Zn II-VI semiconductors

NASA Astrophysics Data System (ADS)

Barlow, D. A.

2017-12-01

The maximum halogen donor concentration in Zn II-VI semiconductors during layer growth is studied using a standard model from statistical mechanics. Here the driving force for incorporation is an increase in entropy upon mixing of the donor impurity into the available anion lattice sites in the host binary. A formation energy opposes this increase and thus equilibrium is attained at some maximum concentration. Considering the halogen donor impurities within the Zn II-VI binary semiconductors ZnO, ZnS, ZnSe and ZnTe, a heat of reaction obtained from reported diatomic bond strengths is shown to be directly proportional to the log of maximum donor concentration. The formation energy can then be estimated and an expression for maximum donor concentration derived. Values for the maximum donor concentration with each of the halogen impurities, within the Zn II-VI compounds, are computed. This model predicts that the halogens will serve as electron donors in these compounds in order of increasing effectiveness as: F, Br, I, Cl. Finally, this result is taken to be equivalent to an alternative model where donor concentration depends upon impurity diffusion and the conduction band energy shift due to a depletion region at the growing crystal's surface. From this, we are able to estimate the diffusion activation energy for each of the impurities mentioned above. Comparisons are made with reported values and relevant conclusions presented.

Photo-induced electron transfer method

DOEpatents

Wohlgemuth, R.; Calvin, M.

1984-01-24

The efficiency of photo-induced electron transfer reactions is increased and the back transfer of electrons in such reactions is greatly reduced when a photo-sensitizer zinc porphyrin-surfactant and an electron donor manganese porphyrin-surfactant are admixed into phospholipid membranes. The phospholipids comprising said membranes are selected from phospholipids whose head portions are negatively charged. Said membranes are contacted with an aqueous medium in which an essentially neutral viologen electron acceptor is admixed. Catalysts capable of transferring electrons from reduced viologen electron acceptor to hydrogen to produce elemental hydrogen are also included in the aqueous medium. An oxidizable olefin is also admixed in the phospholipid for the purpose of combining with oxygen that coordinates with oxidized electron donor manganese porphyrin-surfactant.

Photo-induced electron transfer method

DOEpatents

Wohlgemuth, Roland; Calvin, Melvin

1984-01-01

The efficiency of photo-induced electron transfer reactions is increased and the back transfer of electrons in such reactions is greatly reduced when a photo-sensitizer zinc porphyrin-surfactant and an electron donor manganese porphyrin-surfactant are admixed into phospho-lipid membranes. The phospholipids comprising said membranes are selected from phospholipids whose head portions are negatively charged. Said membranes are contacted with an aqueous medium in which an essentially neutral viologen electron acceptor is admixed. Catalysts capable of transfering electrons from reduced viologen electron acceptor to hydrogen to produce elemental hydrogen are also included in the aqueous medium. An oxidizable olefin is also admixed in the phospholipid for the purpose of combining with oxygen that coordinates with oxidized electron donor manganese porphyrin-surfactant.

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.

Reductive dechlorination of trichloroethene DNAPL source zones: source zone architecture versus electron donor availability

NASA Astrophysics Data System (ADS)

Krol, M.; Kokkinaki, A.; Sleep, B.

2014-12-01

The persistence of dense-non-aqueous-phase liquids (DNAPLs) in the subsurface has led practitioners and regulatory agencies to turn towards low-maintenance, low-cost remediation methods. Biological degradation has been suggested as a possible solution, based on the well-proven ability of certain microbial species to break down dissolved chlorinated ethenes under favorable conditions. However, the biodegradation of pure phase chlorinated ethenes is subject to additional constraints: the continuous release of electron acceptor at a rate governed by mass transfer kinetics, and the temporal and spatial heterogeneity of DNAPL source zones which leads to spatially and temporally variable availability of the reactants for reductive dechlorination. In this work, we investigate the relationship between various DNAPL source zone characteristics and reaction kinetics using COMPSIM, a multiphase groundwater model that considers non-equilibrium mass transfer and Monod-type kinetics for reductive dechlorination. Numerical simulations are performed for simple, homogeneous trichloroethene DNAPL source zones to demonstrate the effect of single source zone characteristics, as well as for larger, more realistic heterogeneous source zones. It is shown that source zone size, and mass transfer kinetics may have a decisive effect on the predicted bio-enhancement. Finally, we evaluate the performance of DNAPL bioremediation for realistic, thermodynamically constrained, concentrations of electron donor. Our results indicate that the latter may be the most important limitation for the success of DNAPL bioremediation, leading to reduced bio-enhancement and, in many cases, comparable performance with water flooding.

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.

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.

Electric-field control of a hydrogenic donor's spin in a semiconductor

NASA Astrophysics Data System (ADS)

de, Amrit; Pryor, Craig E.; Flatté, Michael E.

2009-03-01

The orbital wave function of an electron bound to a single donor in a semiconductor can be modulated by an applied AC electric field, which affects the electron spin dynamics via the spin-orbit interaction. Numerical calculations of the spin dynamics of a single hydrogenic donor (Si) using a real-space multi-band k.p formalism show that in addition to breaking the high symmetry of the hydrogenic donor state, the g-tensor has a strong nonlinear dependence on the applied fields. By explicitly integrating the time dependent Schr"odinger equation it is seen that Rabi oscillations can be obtained for electric fields modulated at sub-harmonics of the Larmor frequency. The Rabi frequencies obtained from sub-harmonic modulation depend on the magnitudes of the AC and DC components of the electric field. For a purely AC field, the highest Rabi frequency is obtained when E is driven at the 2nd sub-harmonic of the Larmor frequency. Apart from suggesting ways to measure g-tensor anisotropies and nonlinearities, these results also suggest the possibility of direct frequency domain measurements of Rabi frequencies.

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.

Electron Bifurcation: Thermodynamics and Kinetics of Two-Electron Brokering in Biological Redox Chemistry.

PubMed

Zhang, Peng; Yuly, Jonathon L; Lubner, Carolyn E; Mulder, David W; King, Paul W; Peters, John W; Beratan, David N

2017-09-19

How can proteins drive two electrons from a redox active donor onto two acceptors at very different potentials and distances? And how can this transaction be conducted without dissipating very much energy or violating the laws of thermodynamics? Nature appears to have addressed these challenges by coupling thermodynamically uphill and downhill electron transfer reactions, using two-electron donor cofactors that have very different potentials for the removal of the first and second electron. Although electron bifurcation is carried out with near perfection from the standpoint of energy conservation and electron delivery yields, it is a biological energy transduction paradigm that has only come into focus recently. This Account provides an exegesis of the biophysical principles that underpin electron bifurcation. Remarkably, bifurcating electron transfer (ET) proteins typically send one electron uphill and one electron downhill by similar energies, such that the overall reaction is spontaneous, but not profligate. Electron bifurcation in the NADH-dependent reduced ferredoxin: NADP + oxidoreductase I (Nfn) is explored in detail here. Recent experimental progress in understanding the structure and function of Nfn allows us to dissect its workings in the framework of modern ET theory. The first electron that leaves the two-electron donor flavin (L-FAD) executes a positive free energy "uphill" reaction, and the departure of this electron switches on a second thermodynamically spontaneous ET reaction from the flavin along a second pathway that moves electrons in the opposite direction and at a very different potential. The singly reduced ET products formed from the bifurcating flavin are more than two nanometers distant from each other. In Nfn, the second electron to leave the flavin is much more reducing than the first: the potentials are said to be "crossed." The eventually reduced cofactors, NADH and ferredoxin in the case of Nfn, perform crucial downstream redox

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.

Release of MEMS devices with hard-baked polyimide sacrificial layer

NASA Astrophysics Data System (ADS)

Boroumand Azad, Javaneh; Rezadad, Imen; Nath, Janardan; Smith, Evan; Peale, Robert E.

2013-03-01

Removal of polyimides used as sacrificial layer in fabricating MEMS devices can be challenging after hardbaking, which may easily result by the end of multiple-step processing. We consider the specific commercial co-developable polyimide ProLift 100 (Brewer Science). Excessive heat hardens this material, so that during wet release in TMAH based solvents, intact sheets break free from the substrate, move around in the solution, and break delicate structures. On the other hand, dry reactive-ion etching of hard-baked ProLift is so slow, that MEMS structures are damaged from undesirably-prolonged physical bombardment by plasma ions. We found that blanket exposure to ultraviolet light allows rapid dry etch of the ProLift surrounding the desired structures without damaging them. Subsequent removal of ProLift from under the devices can then be safely performed using wet or dry etch. We demonstrate the approach on PECVD-grown silicon-oxide cantilevers of 100 micron × 100 micron area supported 2 microns above the substrate by ~100-micron-long 8-micron-wide oxide arms.

The C-type Arabidopsis thioredoxin reductase ANTR-C acts as an electron donor to 2-Cys peroxiredoxins in chloroplasts

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

Moon, Jeong Chan; Jang, Ho Hee; Chae, Ho Byoung

2006-09-22

2-Cys peroxiredoxins (Prxs) play important roles in the antioxidative defense systems of plant chloroplasts. In order to determine the interaction partner for these proteins in Arabidopsis, we used a yeast two-hybrid screening procedure with a C175S-mutant of Arabidopsis 2-Cys Prx-A as bait. A cDNA encoding an NADPH-dependent thioredoxin reductase (NTR) isotype C was identified and designated ANTR-C. We demonstrated that this protein effected efficient transfer of electrons from NADPH to the 2-Cys Prxs of chloroplasts. Interaction between 2-Cys Prx-A and ANTR-C was confirmed by a pull-down experiment. ANTR-C contained N-terminal TR and C-terminal Trx domains. It exhibited both TR andmore » Trx activities and co-localized with 2-Cys Prx-A in chloroplasts. These results suggest that ANTR-C functions as an electron donor for plastidial 2-Cys Prxs and represents the NADPH-dependent TR/Trx system in chloroplasts.« less

Next Generation Highly Conducting Organic Films Using Novel Donor-Acceptor Molecules for Opto-electronic Applications

DTIC Science & Technology

2010-06-01

addition, a new class of donor molecules was invented in the course of the DRI program. 2.1 Polymer Based Donor-acceptor Material The following work by...average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data...information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information

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

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

Accurate donor electron wave functions from a multivalley effective mass theory.

NASA Astrophysics Data System (ADS)

Pendo, Luke; Hu, Xuedong

Multivalley effective mass (MEM) theories combine physical intuition with a marginal need for computational resources, but they tend to be insensitive to variations in the wavefunction. However, recent papers suggest full Bloch functions and suitable central cell donor potential corrections are essential to replicating qualitative and quantitative features of the wavefunction. In this talk, we consider a variational MEM method that can accurately predict both spectrum and wavefunction of isolated phosphorus donors. As per Gamble et. al, we employ a truncated series representation of the Bloch function with a tetrahedrally symmetric central cell correction. We use a dynamic dielectric constant, a feature commonly seen in tight-binding methods. Uniquely, we use a freely extensible basis of either all Slater- or all Gaussian-type functions. With a large basis able to capture the influence of higher energy eigenstates, this method is well positioned to consider the influence of external perturbations, such as electric field or applied strain, on the charge density. This work is supported by the US Army Research Office (W911NF1210609).

5' modification of duplex DNA with a ruthenium electron donor-acceptor pair using solid-phase DNA synthesis

NASA Technical Reports Server (NTRS)

Frank, Natia L.; Meade, Thomas J.

2003-01-01

Incorporation of metalated nucleosides into DNA through covalent modification is crucial to measurement of thermal electron-transfer rates and the dependence of these rates with structure, distance, and position. Here, we report the first synthesis of an electron donor-acceptor pair of 5' metallonucleosides and their subsequent incorporation into oligonucleotides using solid-phase DNA synthesis techniques. Large-scale syntheses of metal-containing oligonucleotides are achieved using 5' modified phosporamidites containing [Ru(acac)(2)(IMPy)](2+) (acac is acetylacetonato; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (3) and [Ru(bpy)(2)(IMPy)](2+) (bpy is 2,2'-bipyridine; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (4). Duplexes formed with the metal-containing oligonucleotides exhibit thermal stability comparable to the corresponding unmetalated duplexes (T(m) of modified duplex = 49 degrees C vs T(m) of unmodified duplex = 47 degrees C). Electrochemical (3, E(1/2) = -0.04 V vs NHE; 4, E(1/2) = 1.12 V vs NHE), absorption (3, lambda(max) = 568, 369 nm; 4, lambda(max) = 480 nm), and emission (4, lambda(max) = 720 nm, tau = 55 ns, Phi = 1.2 x 10(-)(4)) data for the ruthenium-modified nucleosides and oligonucleotides indicate that incorporation into an oligonucleotide does not perturb the electronic properties of the ruthenium complex or the DNA significantly. In addition, the absence of any change in the emission properties upon metalated duplex formation suggests that the [Ru(bpy)(2)(IMPy)](2+)[Ru(acac)(2)(IMPy)](2+) pair will provide a valuable probe for DNA-mediated electron-transfer studies.

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

Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer

PubMed Central

2012-01-01

The aims of this work are to getter undesirable impurities from low-cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists of applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich PS layer, the electrical properties of the mc-Si wafers were significantly improved. The PS layers, realized on both sides of the mc-Si substrates, were formed by the stain-etching technique. The phosphorus treatment was achieved using a liquid POCl3-based source on both sides of the mc-Si wafers. The realized phosphorus/PS/Si/PS/phosphorus structures were annealed at a temperature ranging between 700°C and 950°C under a controlled O2 atmosphere, which allows phosphorus to diffuse throughout the PS layers and to getter eventual metal impurities towards the phosphorus-doped PS layer. The effect of this gettering procedure was investigated by means of internal quantum efficiency and the dark current–voltage (I-V) characteristics. The minority carrier lifetime measurements were made using a WTC-120 photoconductance lifetime tester. The serial resistance and the shunt resistance carried out from the dark I-V curves confirm this gettering-related solar cell improvement. It has been shown that the photovoltaic parameters of the gettered silicon solar cells were improved with regard to the ungettered one, which proves the beneficial effect of this gettering process on the conversion efficiency of the multicrystalline silicon solar cells. PMID:22846070

Transport of spin qubits with donor chains under realistic experimental conditions

NASA Astrophysics Data System (ADS)

Mohiyaddin, Fahd A.; Kalra, Rachpon; Laucht, Arne; Rahman, Rajib; Klimeck, Gerhard; Morello, Andrea

2016-07-01

The ability to transport quantum information across some distance can facilitate the design and operation of a quantum processor. One-dimensional spin chains provide a compact platform to realize scalable spin transport for a solid-state quantum computer. Here, we model odd-sized donor chains in silicon under a range of experimental nonidealities, including variability of donor position within the chain. We show that the tolerance against donor placement inaccuracies is greatly improved by operating the spin chain in a mode where the electrons are confined at the Si-SiO2 interface. We then estimate the required time scales and exchange couplings, and the level of noise that can be tolerated to achieve high-fidelity transport. We also propose a protocol to calibrate and initialize the chain, thereby providing a complete guideline for realizing a functional donor chain and utilizing it for spin transport.

Single molecule-level study of donor-acceptor interactions and nanoscale environment in blends

NASA Astrophysics Data System (ADS)

Quist, Nicole; Grollman, Rebecca; Rath, Jeremy; Robertson, Alex; Haley, Michael; Anthony, John; Ostroverkhova, Oksana

2017-02-01

Organic semiconductors have attracted considerable attention due to their applications in low-cost (opto)electronic devices. The most successful organic materials for applications that rely on charge carrier generation, such as solar cells, utilize blends of several types of molecules. In blends, the local environment strongly influences exciton and charge carrier dynamics. However, relationship between nanoscale features and photophysics is difficult to establish due to the lack of necessary spatial resolution. We use functionalized fluorinated pentacene (Pn) molecule as single molecule probes of intermolecular interactions and of the nanoscale environment in blends containing donor and acceptor molecules. Single Pn donor (D) molecules were imaged in PMMA in the presence of acceptor (A) molecules using wide-field fluorescence microscopy. Two sample configurations were realized: (i) a fixed concentration of Pn donor molecules, with increasing concentration of acceptor molecules (functionalized indenflouorene or PCBM) and (ii) a fixed concentration of acceptor molecules with an increased concentration of the Pn donor. The D-A energy transfer and changes in the donor emission due to those in the acceptor- modified polymer morphology were quantified. The increase in the acceptor concentration was accompanied by enhanced photobleaching and blinking of the Pn donor molecules. To better understand the underlying physics of these processes, we modeled photoexcited electron dynamics using Monte Carlo simulations. The simulated blinking dynamics were then compared to our experimental data, and the changes in the transition rates were related to the changes in the nanoscale environment. Our study provides insight into evolution of nanoscale environment during the formation of bulk heterojunctions.

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.

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.

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.

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

A Cu-Zn nanoparticle promoter for selective carbon dioxide reduction and its application in visible-light-active Z-scheme systems using water as an electron donor.

PubMed

Yin, Ge; Sako, Hiroshi; Gubbala, Ramesh V; Ueda, Shigenori; Yamaguchi, Akira; Abe, Hideki; Miyauchi, Masahiro

2018-04-17

Selective carbon dioxide photoreduction to produce formic acid was achieved under visible light irradiation using water molecules as electron donors, similar to natural plants, based on the construction of a Z-scheme light harvesting system modified with a Cu-Zn alloy nanoparticle co-catalyst. The faradaic efficiency of our Z-scheme system for HCOOH generation was over 50% under visible light irradiation.

Fabrication of scalable and structured tissue engineering scaffolds using water dissolvable sacrificial 3D printed moulds.

PubMed

Mohanty, Soumyaranjan; Larsen, Layla Bashir; Trifol, Jon; Szabo, Peter; Burri, Harsha Vardhan Reddy; Canali, Chiara; Dufva, Marin; Emnéus, Jenny; Wolff, Anders

2015-10-01

One of the major challenges in producing large scale engineered tissue is the lack of ability to create large highly perfused scaffolds in which cells can grow at a high cell density and viability. Here, we explore 3D printed polyvinyl alcohol (PVA) as a sacrificial mould in a polymer casting process. The PVA mould network defines the channels and is dissolved after curing the polymer casted around it. The printing parameters determined the PVA filament density in the sacrificial structure and this density resulted in different stiffness of the corresponding elastomer replica. It was possible to achieve 80% porosity corresponding to about 150 cm(2)/cm(3) surface to volume ratio. The process is easily scalable as demonstrated by fabricating a 75 cm(3) scaffold with about 16,000 interconnected channels (about 1m(2) surface area) and with a channel to channel distance of only 78 μm. To our knowledge this is the largest scaffold ever to be produced with such small feature sizes and with so many structured channels. The fabricated scaffolds were applied for in-vitro culturing of hepatocytes over a 12-day culture period. Smaller scaffolds (6×4 mm) were tested for cell culturing and could support homogeneous cell growth throughout the scaffold. Presumably, the diffusion of oxygen and nutrient throughout the channel network is rapid enough to support cell growth. In conclusion, the described process is scalable, compatible with cell culture, rapid, and inexpensive. Copyright © 2015. Published by Elsevier B.V.

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.

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.

Self-Assembly of Electron Donor-Acceptor-Based Carbazole Derivatives: Novel Fluorescent Organic Nanoprobes for Both One- and Two-Photon Cellular Imaging.

PubMed

Zhang, Jinfeng; Chen, Wencheng; Kalytchuk, Sergii; Li, King Fai; Chen, Rui; Adachi, Chihaya; Chen, Zhan; Rogach, Andrey L; Zhu, Guangyu; Yu, Peter K N; Zhang, Wenjun; Cheah, Kok Wai; Zhang, Xiaohong; Lee, Chun-Sing

2016-05-11

In this study, we report fluorescent organic nanoprobes with intense blue, green, and orange-red emissions prepared by self-assembling three carbazole derivatives into nanorods/nanoparticles. The three compounds consist of two or four electron-donating carbazole groups linked to a central dicyanobenzene electron acceptor. Steric hindrance from the carbazole groups leads to noncoplanar 3D molecular structures favorable to fluorescence in the solid state, while the donor-acceptor structures endow the molecules with good two-photon excited emission properties. The fluorescent organic nanoprobes exhibit good water dispersibility, low cytotoxicity, superior resistance against photodegradation and photobleaching. Both one- and two-photon fluorescent imaging were shown in the A549 cell line. Two-photon fluorescence imaging with the fluorescent probes was demonstrated to be more effective in visualizing and distinguishing cellular details compared to conventional one-photon fluorescence imaging.

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.

Structural Design Principle of Small-Molecule Organic Semiconductors for Metal-Free, Visible-Light-Promoted Photocatalysis.

PubMed

Wang, Lei; Huang, Wei; Li, Run; Gehrig, Dominik; Blom, Paul W M; Landfester, Katharina; Zhang, Kai A I

2016-08-08

Herein, we report on the structural design principle of small-molecule organic semiconductors as metal-free, pure organic and visible light-active photocatalysts. Two series of electron-donor and acceptor-type organic semiconductor molecules were synthesized to meet crucial requirements, such as 1) absorption range in the visible region, 2) sufficient photoredox potential, and 3) long lifetime of photogenerated excitons. The photocatalytic activity was demonstrated in the intermolecular C-H functionalization of electron-rich heteroaromates with malonate derivatives. A mechanistic study of the light-induced electron transport between the organic photocatalyst, substrate, and the sacrificial agent are described. With their tunable absorption range and defined energy-band structure, the small-molecule organic semiconductors could offer a new class of metal-free and visible light-active photocatalysts for chemical reactions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Bioactive gyroid scaffolds formed by sacrificial templating of nanocellulose and nanochitin hydrogels as instructive platforms for biomimetic tissue engineering.

PubMed

Torres-Rendon, Jose Guillermo; Femmer, Tim; De Laporte, Laura; Tigges, Thomas; Rahimi, Khosrow; Gremse, Felix; Zafarnia, Sara; Lederle, Wiltrud; Ifuku, Shinsuke; Wessling, Matthias; Hardy, John G; Walther, Andreas

2015-05-20

A sacrificial templating process using lithographically printed minimal surface structures allows complex de novo geo-metries of delicate hydrogel materials. The hydrogel scaffolds based on cellulose and chitin nanofibrils show differences in terms of attachment of human mesenchymal stem cells, and allow their differentiation into osteogenic outcomes. The approach here serves as a first example toward designer hydrogel scaffolds viable for biomimetic tissue engineering. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Anionic Four Electron Donor-Based Palladacycles as Catalysts for Addition Reactions of Arylboronic Acids with α,β-Unsaturated Ketones, Aldehydes and α-Ketoesters

PubMed Central

He, Ping; Lu, Yong; Dong, Cheng-Guo; Hu, Qiao-Sheng

2008-01-01

Anionic four electron donor-based palladacycle-catalyzed 1,4-additions of arylboronic acids with α,β-unsaturated ketones and 1,2-additions of arylboronic acids with aldehydes and α-ketoesters are described. Our study demonstrated that palladacycles were highly efficient, practical catalysts for these addition reactions. The work described here not only opened a new paradigm for the application of palladacycles, but may also pave the road for other metalacycles as practically useful catalysts for such addition reactions including asymmetric ones. PMID:17217300

Effects of Alkylthio and Alkoxy Side Chains in Polymer Donor Materials for Organic Solar Cells.

PubMed

Cui, Chaohua; Wong, Wai-Yeung

2016-02-01

Side chains play a considerable role not only in improving the solubility of polymers for solution-processed device fabrication, but also in affecting the molecular packing, electron affinity and thus the device performance. In particular, electron-donating side chains show unique properties when employed to tune the electronic character of conjugated polymers in many cases. Therefore, rational electron-donating side chain engineering can improve the photovoltaic properties of the resulting polymer donors to some extent. Here, a survey of some representative examples which use electron-donating alkylthio and alkoxy side chains in conjugated organic polymers for polymer solar cell applications will be presented. It is envisioned that an analysis of the effect of such electron-donating side chains in polymer donors would contribute to a better understanding of this kind of side chain behavior in solution-processed conjugated organic polymers for polymer solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transport of spin qubits with donor chains under realistic experimental conditions

DOE PAGES

Mohiyaddin, Fahd A.; Kalra, Rachpon; Laucht, Arne; ...

2016-07-25

The ability to transport quantum information across some distance can facilitate the design and operation of a quantum processor. One-dimensional spin chains provide a compact platform to realize scalable spin transport for a solid-state quantum computer. Here, we model odd-sized donor chains in silicon under a range of experimental nonidealities, including variability of donor position within the chain. We show that the tolerance against donor placement inaccuracies is greatly improved by operating the spin chain in a mode where the electrons are confined at the Si-SiO 2 interface. We then estimate the required time scales and exchange couplings, and themore » level of noise that can be tolerated to achieve high-fidelity transport. As a result, we also propose a protocol to calibrate and initialize the chain, thereby providing a complete guideline for realizing a functional donor chain and utilizing it for spin transport.« less

[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.

Photoinduced electron transfer between benzyloxy dendrimer phthalocyanine and benzoquinone

NASA Astrophysics Data System (ADS)

Zhang, Tiantian; Ma, Dongdong; Pan, Sujuan; Wu, Shijun; Jiang, Yufeng; Zeng, Di; Yang, Hongqin; Peng, Yiru

2016-10-01

Photo-induced electron transfer (PET) is an important and fundamental process in natural photosynthesis. To mimic such interesting PET process, a suitable donor and acceptor couple were properly chosen. Dendrimer phthalocyanines and their derivatives have emerged as promising materials for artificial photosynthesis systems. In this paper, the electron transfer between the light harvest dendrimer phthalocyanine (donor) and the 1,4-benzoquinone (acceptor) was studied by UV/Vis and fluorescence spectroscopic methods. It was found that fluorescence of phthalocyanine was quenched by benzoquinone (BQ) via excited state electron transfer, from the phthalocyanine to the BQ upon excitation at 610 nm. The Stern-Volmer constant (KSV) of electron transfer was calculated. Our study suggests that this dendritic phthalocyanine is an effective new electron donor and transmission complex and could be used as a potential artificial photosynthesis system.

Fullerene C{sub 70} as a p-type donor in organic photovoltaic cells

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

Zhuang, Taojun; Wang, Xiao-Feng, E-mail: charles1976110@hotmail.com, E-mail: zrhong@ucla.edu, E-mail: kid@yz.yamagata-u.ac.jp; Sano, Takeshi

2014-09-01

Fullerenes and their derivatives have been widely used as n-type materials in organic transistor and photovoltaic devices. Though it is believed that they shall be ambipolar in nature, there have been few direct experimental proofs for that. In this work, fullerene C{sub 70}, known as an efficient acceptor, has been employed as a p-type electron donor in conjunction with 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile as an electron acceptor in planar-heterojunction (PHJ) organic photovoltaic (OPV) cells. High fill factors (FFs) of more than 0.70 were reliably achieved with the C{sub 70} layer even up to 100 nm thick in PHJ cells, suggesting the superior potentialmore » of fullerene C{sub 70} as the p-type donor in comparison to other conventional donor materials. The optimal efficiency of these unconventional PHJ cells was 2.83% with a short-circuit current of 5.33 mA/cm{sup 2}, an open circuit voltage of 0.72 V, and a FF of 0.74. The results in this work unveil the potential of fullerene materials as donors in OPV devices, and provide alternative approaches towards future OPV applications.« less

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.

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.

Distribution of potential eye and tissue donors within an Australian teaching hospital.

PubMed

Dutch, Martin J; Denahy, Anthony F

2017-12-11

Eye and Tissue donation has the capacity to transform lives, yet the vast majority of potential in-hospital donors are not recognised. Studies which describe the relative importance of specific units or wards in determining the size of the donor pool are limited. The aim of this study was to map the distribution of potential Eye and Tissue donors within the study hospital. A 12-month retrospective analysis of all patient deaths at the study hospital was undertaken. The ability to donate corneal, heart valve, bone and skin tissue was investigated. Patients were classified as potential donors if they met specific age criteria and had an absence of contraindications based on electronic database search. There were 985 deaths during the study period. Deaths occurred under the care of 26 separate clinical units, and within 28 unique wards and treatment spaces. Four hundred and forty nine (45.6%) patients were identified as potential eye or tissue donors. The majority of potential donors occurred in ICU, Emergency and palliative care units. Of the subset of 328 deaths ≤ 70 years, the frequency of potential tissue donors was 55% (n = 181). ED and ICU had significantly higher frequencies of potential donor than other wards (86 and 77%, p < 0.01). The current study has identified the ED, ICU and PCUs are being important sites for potential Eye and Tissue Donors within our hospital. These will provide an important focus for future interventions to improve the rate of eye and tissue donation.

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.

Magnetic field enhanced electroluminescence in organic light emitting diodes based on electron donor-acceptor exciplex blends

NASA Astrophysics Data System (ADS)

Baniya, Sangita; Basel, Tek; Sun, Dali; McLaughlin, Ryan; Vardeny, Zeev Valy

2016-03-01

A useful process for light harvesting from injected electron-hole pairs in organic light emitting diodes (OLED) is the transfer from triplet excitons (T) to singlet excitons (S) via reverse intersystem crossing (RISC). This process adds a delayed electro-luminescence (EL) emission component that is known as thermally activated delayed fluorescence (TADF). We have studied electron donor (D)/acceptor(A) blends that form an exciplex manifold in which the energy difference, ΔEST between the lowest singlet (S1) and triplet (T1) levels is relatively small (<100 meV), and thus allows RISC at ambient temperature. We found that the EL emission in OLED based on the exciplex blend is enhanced up to 40% by applying a relatively weak magnetic field of 50 mT at ambient. Moreover the MEL response is activated with activation energy similar that of the EL emission. This suggests that the large magneto-EL originates from an additional spin-mixing channel between singlet and triplet states of the generated exciplexes, which is due to TADF. We will report on the MEL dependencies on the temperature, bias voltage, and D-A materials for optimum OLED performance. Supported by SAMSUNG Global Research Outreach (GRO) program, and also by the NSF-Material Science & Engineering Center (MRSEC) program at the University of Utah (DMR-1121252).

Electronic and optical properties of novel carbazole-based donor-acceptor compounds for applications in blue-emitting organic light-emitting diodes

DOE PAGES

Legaspi, Christian M.; Stubbs, Regan E.; Yaron, David J.; ...

2015-08-20

We report that organic light-emitting diodes (OLEDs) have received a significant attention over the past decade due to their energy-saving potential. We have recently synthesized two novel carbazole-based donor-acceptor compounds and analyzed their optical properties to determine their suitability for use as blue emitters in OLEDs. These compounds show remarkable photo-stability and high quantum yields in the blue region of the spectrum. In addition, they have highly solvatochromic emission. In non-polar solvents, bright, blue-shifted (λmax ≈ 398 nm), and highly structured emission is seen. With increasing solvent dielectric constant, the emission becomes weaker, red-shifted (λmax ≈ 507 nm), and broad.more » We aim to determine the underlying cause of these changes. Electronic structure calculations indicate the presence of multiple excited states with comparable oscillator strength. These states are of interest because there are several with charge-transfer (CT) character, and others centered on the donor moiety. We theorize that CT states play a role in the observed changes in emission lineshape and may promote charge mobility for electrofluorescence in OLEDs. In the future, we plan to use Stark spectroscopy to analyze the polarity of excited states and transient absorption spectroscopy to observe the dynamics in the excited state.« less

Electronic and optical properties of novel carbazole-based donor-acceptor compounds for applications in blue-emitting organic light-emitting diodes

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

Legaspi, Christian M.; Stubbs, Regan E.; Yaron, David J.

We report that organic light-emitting diodes (OLEDs) have received a significant attention over the past decade due to their energy-saving potential. We have recently synthesized two novel carbazole-based donor-acceptor compounds and analyzed their optical properties to determine their suitability for use as blue emitters in OLEDs. These compounds show remarkable photo-stability and high quantum yields in the blue region of the spectrum. In addition, they have highly solvatochromic emission. In non-polar solvents, bright, blue-shifted (λmax ≈ 398 nm), and highly structured emission is seen. With increasing solvent dielectric constant, the emission becomes weaker, red-shifted (λmax ≈ 507 nm), and broad.more » We aim to determine the underlying cause of these changes. Electronic structure calculations indicate the presence of multiple excited states with comparable oscillator strength. These states are of interest because there are several with charge-transfer (CT) character, and others centered on the donor moiety. We theorize that CT states play a role in the observed changes in emission lineshape and may promote charge mobility for electrofluorescence in OLEDs. In the future, we plan to use Stark spectroscopy to analyze the polarity of excited states and transient absorption spectroscopy to observe the dynamics in the excited state.« less

Electrochemical Reduction of Carbon Dioxide to Methanol by Direct Injection of Electrons into Immobilized Enzymes on a Modified Electrode.

PubMed

Schlager, Stefanie; Dumitru, Liviu Mihai; Haberbauer, Marianne; Fuchsbauer, Anita; Neugebauer, Helmut; Hiemetsberger, Daniela; Wagner, Annika; Portenkirchner, Engelbert; Sariciftci, Niyazi Serdar

2016-03-21

We present results for direct bio-electrocatalytic reduction of CO2 to C1 products using electrodes with immobilized enzymes. Enzymatic reduction reactions are well known from biological systems where CO2 is selectively reduced to formate, formaldehyde, or methanol at room temperature and ambient pressure. In the past, the use of such enzymatic reductions for CO2 was limited due to the necessity of a sacrificial co-enzyme, such as nicotinamide adenine dinucleotide (NADH), to supply electrons and the hydrogen equivalent. The method reported here in this paper operates without the co-enzyme NADH by directly injecting electrons from electrodes into immobilized enzymes. We demonstrate the immobilization of formate, formaldehyde, and alcohol dehydrogenases on one-and-the-same electrode for direct CO2 reduction. Carbon felt is used as working electrode material. An alginate-silicate hybrid gel matrix is used for the immobilization of the enzymes on the electrode. Generation of methanol is observed for the six-electron reduction with Faradaic efficiencies of around 10%. This method of immobilization of enzymes on electrodes offers the opportunity for electrochemical application of enzymatic electrodes to many reactions in which a substitution of the expensive sacrificial co-enzyme NADH is desired. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations

DOEpatents

Johnson, Jr., James S.; Westmoreland, Clyde G.

1982-01-01

The present invention is directed to a sacrificial or competitive adsorbate for surfactants contained in chemical flooding emulsions for enhanced oil recovery operations. The adsorbate to be utilized in the method of the present invention is a caustic effluent from the bleach stage or the weak black liquor from the digesters and pulp washers of the kraft pulping process. This effluent or weak black liquor is injected into an oil-bearing subterranean earth formation prior to or concurrent with the chemical flood emulsion and is adsorbed on the active mineral surfaces of the formation matrix so as to effectively reduce adsorption of surfactant in the chemical flood. Alternatively, the effluent or liquor can be injected into the subterranean earth formation subsequent to a chemical flood to displace the surfactant from the mineral surfaces for the recovery thereof.

Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations

DOEpatents

Johnson, J.S. Jr.; Westmoreland, C.G.

1980-08-20

The present invention is directed to a sacrificial or competitive adsorbate for surfactants contained in chemical flooding emulsions for enhanced oil recovery operations. The adsorbate to be utilized in the method of the present invention is a caustic effluent from the bleach stage or the weak black liquor from the digesters and pulp washers of the kraft pulping process. This effluent or weak black liquor is injected into an oil-bearing subterranean earth formation prior to or concurrent with the chemical flood emulsion and is adsorbed on the active mineral surfaces of the formation matrix so as to effectively reduce adsorption of surfactant in the chemical flood. Alternatively, the effluent or liquor can be injected into the subterranean earth formation subsequent to a chemical flood to displace the surfactant from the mineral surfaces for the recovery thereof.

Ultrafast dynamics of colloidal semiconductor nanocrystals relevant to solar fuels production

NASA Astrophysics Data System (ADS)

Cogan, Nicole M. B.; Liu, Cunming; Qiu, Fen; Burke, Rebeckah; Krauss, Todd D.

2017-05-01

Artificial conversion of sunlight to chemical fuels has attracted attention for several decades as a potential source of clean, renewable energy. We recently found that CdSe quantum dots (QDs) and simple aqueous Ni2+ salts in the presence of a sacrificial electron donor form a highly efficient, active, and robust system for photochemical reduction of protons to molecular hydrogen. Ultrafast transient absorption spectroscopy studies of electron transfer (ET) processes from the QDs to the Ni catalysts reveal extremely fast ET, and provide a fundamental explanation for the exceptional photocatalytic H2 activity. Additionally, by studying H2 production of the Ni catalyst with CdSe/CdS nanoparticles of various structures, it was determined that surface charge density plays an important role in charge transfer and ultimately H2 production activity.

[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.

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.

Sacrificial adhesive bonding: a powerful method for fabrication of glass microchips

PubMed Central

Lima, Renato S.; Leão, Paulo A. G. C.; Piazzetta, Maria H. O.; Monteiro, Alessandra M.; Shiroma, Leandro Y.; Gobbi, Angelo L.; Carrilho, Emanuel

2015-01-01

A new protocol for fabrication of glass microchips is addressed in this research paper. Initially, the method involves the use of an uncured SU-8 intermediate to seal two glass slides irreversibly as in conventional adhesive bonding-based approaches. Subsequently, an additional step removes the adhesive layer from the channels. This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests. Named sacrificial adhesive layer (SAB), the protocol meets the requirements of an ideal microfabrication technique such as throughput, relatively low cost, feasibility for ultra large-scale integration (ULSI), and high adhesion strength, supporting pressures on the order of 5 MPa. Furthermore, SAB eliminates the use of high temperature, pressure, or potential, enabling the deposition of thin films for electrical or electrochemical experiments. Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature. Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives. PMID:26293346

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.

Molecular engineering of fracture energy dissipating sacrificial bonds into cellulose nanocrystal nanocomposites.

PubMed

McKee, Jason R; Huokuna, Johannes; Martikainen, Lahja; Karesoja, Mikko; Nykänen, Antti; Kontturi, Eero; Tenhu, Heikki; Ruokolainen, Janne; Ikkala, Olli

2014-05-12

Even though nanocomposites have provided a plethora of routes to increase stiffness and strength, achieving increased toughness with suppressed catastrophic crack growth has remained more challenging. Inspired by the concepts of mechanically excellent natural nanomaterials, one-component nanocomposites were fabricated involving reinforcing colloidal nanorod cores with polymeric grafts containing supramolecular binding units. The concept is based on mechanically strong native cellulose nanocrystals (CNC) grafted with glassy polymethacrylate polymers, with side chains that contain 2-ureido-4[1H]-pyrimidone (UPy) pendant groups. The interdigitation of the grafts and the ensuing UPy hydrogen bonds bind the nanocomposite network together. Under stress, UPy groups act as sacrificial bonds: simultaneously providing adhesion between the CNCs while allowing them to first orient and then gradually slide past each other, thus dissipating fracture energy. We propose that this architecture involving supramolecular binding units within side chains of polymer grafts attached to colloidal reinforcements opens generic approaches for tough nanocomposites. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sacrificial limbs of sovereignty: disabled veterans, masculinity, and nationalist politics in Turkey.

PubMed

Açiksöz, Salih Can

2012-03-01

Over the last decade, disabled veterans of the Turkish Army who were injured while fighting against the Partiya Karkerên Kurdistan (PKK; Kurdistan Workers' Party) have become national icons and leading ultranationalist actors. While being valorized as sacrificial heroes in nationalist discourse, they have also confronted socioeconomic marginalization, corporeal otherness, and emasculation anxieties. Against this backdrop, disabled veterans' organizations have become the locus of an ultranationalist campaign against dissident intellectuals. Building on two years of ethnographic research with disabled veterans in Turkey, this article analyzes these processes through the analytical lens of the body. Locating the disabled veteran body at the intersection of state welfare practices, nationalist discourses on heroism and sacrifice, and cultural norms of masculinity and disability, I illustrate how disabled veterans' gendered and classed experiences of disability are hardened into a political identity. Consequently, I show how violence generates new modalities of masculinity and political agency through its corporeal effects.

[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.

Identification of the 2-hydroxyglutarate and isovaleryl-CoA dehydrogenases as alternative electron donors linking lysine catabolism to the electron transport chain of Arabidopsis mitochondria.

PubMed

Araújo, Wagner L; Ishizaki, Kimitsune; Nunes-Nesi, Adriano; Larson, Tony R; Tohge, Takayuki; Krahnert, Ina; Witt, Sandra; Obata, Toshihiro; Schauer, Nicolas; Graham, Ian A; Leaver, Christopher J; Fernie, Alisdair R

2010-05-01

The process of dark-induced senescence in plants is relatively poorly understood, but a functional electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex, which supports respiration during carbon starvation, has recently been identified. Here, we studied the responses of Arabidopsis thaliana mutants deficient in the expression of isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase to extended darkness and other environmental stresses. Evaluations of the mutant phenotypes following carbon starvation induced by extended darkness identify similarities to those exhibited by mutants of the ETF/ETFQO complex. Metabolic profiling and isotope tracer experimentation revealed that isovaleryl-CoA dehydrogenase is involved in degradation of the branched-chain amino acids, phytol, and Lys, while 2-hydroxyglutarate dehydrogenase is involved exclusively in Lys degradation. These results suggest that isovaleryl-CoA dehydrogenase is the more critical for alternative respiration and that a series of enzymes, including 2-hydroxyglutarate dehydrogenase, plays a role in Lys degradation. Both physiological and metabolic phenotypes of the isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase mutants were not as severe as those observed for mutants of the ETF/ETFQO complex, indicating some functional redundancy of the enzymes within the process. Our results aid in the elucidation of the pathway of plant Lys catabolism and demonstrate that both isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase act as electron donors to the ubiquinol pool via an ETF/ETFQO-mediated route.

Characteristics and clinical outcomes of living renal donors in Hong Kong.

PubMed

Hong, Y L; Yee, C H; Leung, C B; Teoh, J Yc; Kwan, B Ch; Li, P Kt; Hou, S Sm; Ng, C F

2018-02-01

In Asia, few reports are available on the outcomes for living renal donors. We report the short- and long-term clinical outcomes of individuals following living donor nephrectomy in Hong Kong. We retrospectively reviewed the characteristics and clinical outcomes of all living renal donors who underwent surgery from January 1990 to December 2015 at a teaching hospital in Hong Kong. Information was obtained from hospital records and territory-wide electronic patient records. During the study period, 83 individuals underwent donor nephrectomy. The mean (± standard deviation) follow-up time was 12.0 ± 8.3 years, and the mean age at nephrectomy was 37.3 ± 10.0 years. A total of 44 (53.0%), four (4.8%), and 35 (42.2%) donors underwent living donor nephrectomy via an open, hand-port assisted laparoscopic, and laparoscopic approach, respectively. The overall incidence of complications was 36.6%, with most being grade 1 or 2. There were three (9.4%) grade 3a complications; all were related to open donor nephrectomy. The mean glomerular filtration rate was 96.0 ± 17.5 mL/min/1.73 m 2 at baseline and significantly lower at 66.8 ± 13.5 mL/min/1.73 m 2 at first annual follow-up (P<0.01). The latest mean glomerular filtration rate was 75.6% ± 15.1% of baseline. No donor died or developed renal failure. Of the donors, 14 (18.2%) developed hypertension, two (2.6%) had diabetes mellitus, and three (4.0%) had experienced proteinuria. The overall perioperative outcomes are good, with very few serious complications. The introduction of a laparoscopic approach has decreased perioperative blood loss and also shortened hospital stay. Long-term kidney function is satisfactory and no patients developed end-stage renal disease. The incidences of new-onset medical diseases and pregnancy-related complications were also low.

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.

Theoretical characterization of photoinduced electron transfer in rigidly linked donor-acceptor molecules: the fragment charge difference and the generalized Mulliken-Hush schemes

NASA Astrophysics Data System (ADS)

Lee, Sheng-Jui; Chen, Hung-Cheng; You, Zhi-Qiang; Liu, Kuan-Lin; Chow, Tahsin J.; Chen, I.-Chia; Hsu, Chao-Ping

2010-10-01

We calculate the electron transfer (ET) rates for a series of heptacyclo[6.6.0.02,6.03,13.014,11.05,9.010,14]-tetradecane (HCTD) linked donor-acceptor molecules. The electronic coupling factor was calculated by the fragment charge difference (FCD) [19] and the generalized Mulliken-Hush (GMH) schemes [20]. We found that the FCD is less prone to problems commonly seen in the GMH scheme, especially when the coupling values are small. For a 3-state case where the charge transfer (CT) state is coupled with two different locally excited (LE) states, we tested with the 3-state approach for the GMH scheme [30], and found that it works well with the FCD scheme. A simplified direct diagonalization based on Rust's 3-state scheme was also proposed and tested. This simplified scheme does not require a manual assignment of the states, and it yields coupling values that are largely similar to those from the full Rust's approach. The overall electron transfer (ET) coupling rates were also calculated.

Toughening elastomers with sacrificial bonds and watching them break

NASA Astrophysics Data System (ADS)

Creton, Costantino

2014-03-01

Most unfilled elastomers are relatively brittle, in particular when the average molecular weight between crosslinks is lower than the average molecular weight between entanglements. We created a new class of tough elastomers by introducing isotropically prestretched chains inside ordinary acrylic elastomers by successive swelling and polymerization steps. These new materials combine a high entanglement density with a densely crosslinked structure reaching elastic moduli of 4 MPa and fracture strength of 25 MPa. The highly prestretched chains are the minority in the material and can break in the bulk of the material before catastrophic failure occurs, increasing the toughness of the material by two orders of magnitude up to 5 kJ/m2. To investigate the details of the toughening mechanism we introduced specific sacrificial dioxetane bonds in the prestretched chains that emit light when they break. In uniaxial extension cyclic experiments, we checked that the light emission corresponded exactly and quantitatively to the energy dissipation in each cycle demonstrating that short chains break first and long chains later. We then watched crack propagation in notched samples and mapped spatially the location of bond breakage ahead of the crack tip before and during propagation. This new toughening mechanism for elastomers creates superentangled rubbers and is ideally suited to overcome the trade-off between toughness and stiffness of ordinary elastomers. We gratefully acknowledge funding from DSM Ahead

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.

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.

Enhanced Efficiency in Fullerene-Free Polymer Solar Cell by Incorporating Fine-designed Donor and Acceptor Materials.

PubMed

Ye, Long; Sun, Kai; Jiang, Wei; Zhang, Shaoqing; Zhao, Wenchao; Yao, Huifeng; Wang, Zhaohui; Hou, Jianhui

2015-05-06

Among the diverse nonfullerene acceptors, perylene bisimides (PBIs) have been attracting much attention due to their excellent electron mobility and tunable molecular and electronic properties by simply engineering the bay and head linkages. Herein, guided by two efficient small molecular acceptors, we designed, synthesized, and characterized a new nonfullerene small molecule PPDI with fine-tailored alkyl chains. Notably, a certificated PCE of 5.40% is realized in a simple structured fullerene-free polymer solar cell comprising PPDI as the electron acceptor and a fine-tailored 2D-conjugated polymer PBDT-TS1 as the electron donor. Moreover, the device behavior, morphological feature, and origin of high efficiency in PBDT-TS1/PPDI-based fullerene-free PSC were investigated. The synchronous selection and design of donor and acceptor materials reported here offer a feasible strategy for realizing highly efficient fullerene-free organic photovoltaics.

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.

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.

The National Heart, Lung, and Blood Institute Recipient Epidemiology and Donor Evaluation Study (REDS-III): A research program striving to improve blood donor and transfusion recipient outcomes

PubMed Central

Kleinman, Steven; Busch, Michael P; Murphy, Edward L; Shan, Hua; Ness, Paul; Glynn, Simone A.

2014-01-01

Background The Recipient Epidemiology and Donor Evaluation Study -III (REDS-III) is a 7-year multicenter transfusion safety research initiative launched in 2011 by the National Heart, Lung, and Blood Institute. Study design The domestic component involves 4 blood centers, 12 hospitals, a data coordinating center, and a central laboratory. The international component consists of distinct programs in Brazil, China, and South Africa which involve US and in-country investigators. Results REDS-III is using two major methods to address key research priorities in blood banking/transfusion medicine. First, there will be numerous analyses of large “core” databases; the international programs have each constructed a donor/donation database while the domestic program has established a detailed research database that links data from blood donors and their donations, the components made from these donations, and data extracts from the electronic medical records of the recipients of these components. Secondly, there are more than 25 focused research protocols involving transfusion recipients, blood donors, or both that are either in progress or scheduled to begin within the next 3 years. Areas of study include transfusion epidemiology and blood utilization; transfusion outcomes; non-infectious transfusion risks; HIV-related safety issues (particularly in the international programs); emerging infectious agents; blood component quality; donor health and safety; and other donor issues. Conclusions It is intended that REDS-III serve as an impetus for more widespread recipient and linked donor-recipient research in the US as well as to help assure a safe and available blood supply in the US and in international locations. PMID:24188564

Polaronic effects on the off-center donor impurity in AlAs/GaAs/SiO2 spherical core/shell quantum dots

NASA Astrophysics Data System (ADS)

El Haouari, M.; Feddi, E.; Dujardin, F.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.

2017-11-01

The ground state of a conduction electron coupled to an off-center impurity donor in a AlAS/GaAs spherical core/shell quantum dot is investigated theoretically. The image-charge effect and the influence of the electron-polar-LO-phonon interaction are considered. The electron-impurity binding energy is calculated via a variational procedure and is reported both as a function of the shell width and of the radial position of the donor atom. The polaronic effects on this quantity are particularly discussed.

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.

Carrier concentration dependence of donor activation energy in n-type GaN epilayers grown on Si (1 1 1) by plasma-assisted MBE

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

Kumar, Mahesh; Central Research Laboratory, Bharat Electronics, Bangalore 560 013; Bhat, Thirumaleshwara N.

Highlights: ► The n-type GaN layers were grown by plasma-assisted molecular beam epitaxy. ► The optical characteristics of a donor level in Si-doped GaN were studied. ► Activation energy of a Si-related donor was estimated from temperature dependent PL measurements. ► PL peak positions, FWHM of PL and activation energies are found to be proportional to the cube root of carrier density. ► The involvement of donor levels is supported by the temperature-dependent electron concentration measurements. -- Abstract: The n-type GaN layers were grown by plasma-assisted MBE and either intentionally doped with Si or unintentionally doped. The optical characteristics ofmore » a donor level in Si-doped, GaN were studied in terms of photoluminescence (PL) spectroscopy as a function of electron concentration. Temperature dependent PL measurements allowed us to estimate the activation energy of a Si-related donor from temperature-induced decay of PL intensity. PL peak positions, full width at half maximum of PL and activation energies are found to be proportional to the cube root of carrier density. The involvement of donor levels is supported by the temperature-dependent electron concentration measurements.« less

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.

Multi-qubit gates protected by adiabaticity and dynamical decoupling applicable to donor qubits in silicon

DOE PAGES

Witzel, Wayne; Montano, Ines; Muller, Richard P.; ...

2015-08-19

In this paper, we present a strategy for producing multiqubit gates that promise high fidelity with minimal tuning requirements. Our strategy combines gap protection from the adiabatic theorem with dynamical decoupling in a complementary manner. Energy-level transition errors are protected by adiabaticity and remaining phase errors are mitigated via dynamical decoupling. This is a powerful way to divide and conquer the various error channels. In order to accomplish this without violating a no-go theorem regarding black-box dynamically corrected gates [Phys. Rev. A 80, 032314 (2009)], we require a robust operating point (sweet spot) in control space where the qubits interactmore » with little sensitivity to noise. There are also energy gap requirements for effective adiabaticity. We apply our strategy to an architecture in Si with P donors where we assume we can shuttle electrons between different donors. Electron spins act as mobile ancillary qubits and P nuclear spins act as long-lived data qubits. Furthermore, this system can have a very robust operating point where the electron spin is bound to a donor in the quadratic Stark shift regime. High fidelity single qubit gates may be performed using well-established global magnetic resonance pulse sequences. Single electron-spin preparation and measurement has also been demonstrated. Thus, putting this all together, we present a robust universal gate set for quantum computation.« less

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.

Attaching naphthalene derivatives onto BODIPY for generating excited triplet state and singlet oxygen: Tuning PET-based photosensitizer by electron donors

NASA Astrophysics Data System (ADS)

Zhang, Xian-Fu; Feng, Nan

2018-01-01

meso-Naphthalene substituted BODIPY compounds were prepared in a facile one pot reaction. The naphthalene functionalization of BODIPY leads up to a 5-fold increase in the formation efficiency of excited triplet state and singlet oxygen in polar solvents. Steady state and time resolved fluorescence, laser flash photolysis, and quantum chemistry methods were used to reveal the mechanism. All measured data and quantum chemical results suggest that these systems can be viewed as electron donor-acceptor (D-A) pair (BODIPY acts as the acceptor), photoinduced charge transfer (PCT) or photoinduced electron transfer (PET) occurs upon photo excitation (D-A + hν → Dδ +-Aδ -, 0 < δ ≤ 1), and the charge recombination induced the formation of triplet state (Dδ +-Aδ - → D-A (T1). These novel PCT- or PET-based photosensitizers (PSs) show different features from traditional PSs, such as the strong tunability by facile structural modification and good selectivity upon medium polarity. The new character for this type of PSs can lead to important applications in organic oxygenation reactions and photodynamic therapy of tumors.

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.

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.

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 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

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...

Tunable Rh 2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation

DOE PAGES

Whittemore, Tyler; Millet, Agustin; Sayre, Hannah; ...

2018-04-04

In this study, a series of dirhodium(II,II) paddlewheeel complexes of the type cis-[Rh 2(μ-DTolF) 2(μ-L) 2][BF 4] 2, where DTolF = N,N'-di(p-tolyl)formamidinate and L = 1,8-naphthyridine (np), 2-(pyridin-2-yl)-1,8-naphthyridine (pynp), 2-(quinolin-2-yl)-1,8-naphthyridine (qnnp), and 2-(1,8-naphthyridin-2-yl)quinoxaline (qxnp), were synthesized and characterized. These molecules feature new tridentate ligands that concomitantly bridge the dirhodium core and cap the axial positions. The complexes absorb light strongly throughout the ultraviolet/visible range and into the near-infrared region and exhibit relatively long-lived triplet excited-state lifetimes. Both the singlet and triplet excited states exhibit metal/ligand-to-ligand charge transfer (ML-LCT) in nature as determined by transient absorption spectroscopy and spectroelectrochemistry measurements. Whenmore » irradiated with low-energy light, these black dyes are capable of undergoing reversible bimolecular electron transfer both to the electron acceptor methyl viologen and from the electron donor p-phenylenediamine. Photoinduced charge transfer in the latter was inaccessible with previous Rh 2(II,II) complexes. Finally, these results underscore the fact that the excited state of this class of molecules can be readily tuned for electron-transfer reactions upon simple synthetic modification and highlight their potential as excellent candidates for p- and n-type semiconductor applications and for improved harvesting of low-energy light to drive useful photochemical reactions.« less

Tunable Rh 2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation

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

Whittemore, Tyler; Millet, Agustin; Sayre, Hannah

In this study, a series of dirhodium(II,II) paddlewheeel complexes of the type cis-[Rh 2(μ-DTolF) 2(μ-L) 2][BF 4] 2, where DTolF = N,N'-di(p-tolyl)formamidinate and L = 1,8-naphthyridine (np), 2-(pyridin-2-yl)-1,8-naphthyridine (pynp), 2-(quinolin-2-yl)-1,8-naphthyridine (qnnp), and 2-(1,8-naphthyridin-2-yl)quinoxaline (qxnp), were synthesized and characterized. These molecules feature new tridentate ligands that concomitantly bridge the dirhodium core and cap the axial positions. The complexes absorb light strongly throughout the ultraviolet/visible range and into the near-infrared region and exhibit relatively long-lived triplet excited-state lifetimes. Both the singlet and triplet excited states exhibit metal/ligand-to-ligand charge transfer (ML-LCT) in nature as determined by transient absorption spectroscopy and spectroelectrochemistry measurements. Whenmore » irradiated with low-energy light, these black dyes are capable of undergoing reversible bimolecular electron transfer both to the electron acceptor methyl viologen and from the electron donor p-phenylenediamine. Photoinduced charge transfer in the latter was inaccessible with previous Rh 2(II,II) complexes. Finally, these results underscore the fact that the excited state of this class of molecules can be readily tuned for electron-transfer reactions upon simple synthetic modification and highlight their potential as excellent candidates for p- and n-type semiconductor applications and for improved harvesting of low-energy light to drive useful photochemical reactions.« less

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.

Charge Transfer and Collection in Dilute Organic Donor-Acceptor Heterojunction Blends.

PubMed

Ding, Kan; Liu, Xiao; Forrest, Stephen R

2018-05-09

Experimental and theoretical approaches are used to understand the role of nanomorphology on exciton dissociation and charge collection at dilute donor-acceptor (D-A) organic heterojunctions (HJs). Specifically, two charge transfer (CT) states in D-A mixed HJs comprising nanocrystalline domains of tetraphenyldibenzoperiflanthene (DBP) as the donor and C 70 as the acceptor are unambiguously related to the nanomorphology of the mixed layer. Alternating DBP:C 70 multilayer stacks are used to identify and control the optical properties of the CT states, as well as to simulate the dilute mixed heterojunctions. A kinetic Monte Carlo model along with photoluminescence spectroscopy and scanning transmission electron microscopy are used to quantitatively evaluate the layer morphology under various growth conditions. As a result, we are able to understand the counterintuitive observation of high charge extraction efficiency and device performance of DBP:C 70 mixed layer photovoltaics at surprisingly low (∼10%) donor concentrations.

Design and Synthesis of Novel Block Copolymers for Efficient Opto-Electronic Applications

NASA Technical Reports Server (NTRS)

Sun, Sam-Shajing; Fan, Zhen; Wang, Yiqing; Taft, Charles; Haliburton, James; Maaref, Shahin

2002-01-01

It has been predicted that nano-phase separated block copolymer systems containing electron rich donor blocks and electron deficient acceptor blocks may facilitate the charge carrier separation and migration in organic photovoltaic devices due to improved morphology in comparison to polymer blend system. This paper presents preliminary data describing the design and synthesis of a novel Donor-Bridge-Acceptor (D-B-A) block copolymer system for potential high efficient organic optoelectronic applications. Specifically, the donor block contains an electron donating alkyloxy derivatized polyphenylenevinylene (PPV), the acceptor block contains an electron withdrawing alkyl-sulfone derivatized polyphenylenevinylene (PPV), and the bridge block contains an electronically neutral non-conjugated aliphatic hydrocarbon chain. The key synthetic strategy includes the synthesis of each individual block first, then couple the blocks together. While the donor block stabilizes and facilitates the transport of the holes, the acceptor block stabilizes and facilitates the transport of the electrons, the bridge block is designed to hinder the probability of electron-hole recombination. Thus, improved charge separation and stability are expected with this system. In addition, charge migration toward electrodes may also be facilitated due to the potential nano-phase separated and highly ordered block copolymer ultra-structure.

Negative polarity of phenyl-C{sub 61} butyric acid methyl ester adjacent to donor macromolecule domains

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

Alley, Olivia J.; Dawidczyk, Thomas J.; Hardigree, Josué F. Martínez

2015-01-19

Interfacial fields within organic photovoltaics influence the movement of free charge carriers, including exciton dissociation and recombination. Open circuit voltage (V{sub oc}) can also be dependent on the interfacial fields, in the event that they modulate the energy gap between donor HOMO and acceptor LUMO. A rise in the vacuum level of the acceptor will increase the gap and the V{sub oc}, which can be beneficial for device efficiency. Here, we measure the interfacial potential differences at donor-acceptor junctions using Scanning Kelvin Probe Microscopy, and quantify how much of the potential difference originates from physical contact between the donor andmore » acceptor. We see a statistically significant and pervasive negative polarity on the phenyl-C{sub 61} butyric acid methyl ester (PCBM) side of PCBM/donor junctions, which should also be present at the complex interfaces in bulk heterojunctions. This potential difference may originate from molecular dipoles, interfacial interactions with donor materials, and/or equilibrium charge transfer due to the higher work function and electron affinity of PCBM. We show that the contact between PCBM and poly(3-hexylthiophene) doubles the interfacial potential difference, a statistically significant difference. Control experiments determined that this potential difference was not due to charges trapped in the underlying substrate. The direction of the observed potential difference would lead to increased V{sub oc}, but would also pose a barrier to electrons being injected into the PCBM and make recombination more favorable. Our method may allow unique information to be obtained in new donor-acceptor junctions.« less

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.