| 1. |
- Faatz, B., et al.
(author)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Journal article (peer-reviewed)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 2. |
- Qian, D. P., et al.
(author)
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Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells
- 2015
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 3:48, s. 24349-24357
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Journal article (peer-reviewed)abstract
- In conjugated polymers and small molecules of organic solar cells, aggregation induced by intermolecular interactions governs the performance of photovoltaics. However, little attention has been paid to the connection between molecular structure and aggregation within solar cells based on soluble small molecules. Here we demonstrate modulation of intermolecular aggregation of two synthesized molecules through heteroatom substitution to develop an understanding of the role of aggregation in conjugated molecules. Molecule 1 (M1) based on 2-ethylhexyloxy-benzene substituted benzo[1,2-b:4,5-b']dithiophene (BDTP) and diketopyrrolopyrrole (DPP) displays strong aggregation in commonly used organic solvents, which is reduced in molecule 2 (M2) by facile oxygen atom substitution on the BDTP unit confirmed by absorption spectroscopy and optical microscopy, while it successfully maintains molecular planarity and favorable charge transport characteristics. Solar cells based on M2 exhibit more than double the photocurrent of devices based on M1 and yield a power conversion efficiency of 5.5%. A systematic investigation of molecular conformation, optoelectronic properties, molecular packing and crystallinity as well as film morphology reveals structure dependent aggregation responsible for the performance difference between the two conjugated molecules.
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| 3. |
- Agirre, Jon, et al.
(author)
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The CCP4 suite: integrative software for macromolecular crystallography
- 2023
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In: Acta Crystallographica Section D. - : INT UNION CRYSTALLOGRAPHY. - 2059-7983. ; 79, s. 449-461
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Journal article (peer-reviewed)abstract
- The Collaborative Computational Project No. 4 (CCP4) is a UK-led international collective with a mission to develop, test, distribute and promote software for macromolecular crystallography. The CCP4 suite is a multiplatform collection of programs brought together by familiar execution routines, a set of common libraries and graphical interfaces. The CCP4 suite has experienced several considerable changes since its last reference article, involving new infrastructure, original programs and graphical interfaces. This article, which is intended as a general literature citation for the use of the CCP4 software suite in structure determination, will guide the reader through such transformations, offering a general overview of the new features and outlining future developments. As such, it aims to highlight the individual programs that comprise the suite and to provide the latest references to them for perusal by crystallographers around the world.
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| 4. |
- Che, Canyan, 1988-, et al.
(author)
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Twinning Lignosulfonate with a Conducting Polymer via Counter-Ion Exchange for Large-Scale Electrical Storage
- 2019
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In: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:9
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Journal article (peer-reviewed)abstract
- Lignosulfonate (LS) is a large-scale surplus product of the forest and paper industries, and has primarily been utilized as a low-cost plasticizer in making concrete for the construction industry. LS is an anionic redox-active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox-supercapacitors. Here, the physical-chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter-ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer–polymer interactions are optimized to exploit the biopolymer-associated redox currents. Further, the explored LS-conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up-scaling effort toward large-scale electrical energy storage technology. By using an up-scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter-ion exchange is confirmed and the PEDOT-LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g−1.
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| 5. |
- Kovtun, A.A., Vagin, S.A., Vardaniants, I.L., Legen’kova, N.P., Smirnov, M.Yu., Uspensky, N.I., and the BEAR Working Group
(author)
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Analysis of Magnetotelluric and Magnetic Variation results in a Daily Variation Range from BEAR Data and the Construction of the Normal Section of the Baltic Shield
- 2002
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In: Izvestiya, Physics of the Solid Earth. ; 38:11, s. 935-953
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Journal article (peer-reviewed)
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| 6. |
- Sekretareva, Alina, et al.
(author)
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Total phenol analysis of water using a laccase-based microsensor array
- 2015
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In: Program of the XXIII International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society. 14-18 June, 2015. Malmö, Sweden. - Lausanne : Bioelectrochemical Society. ; , s. 155-155
-
Conference paper (other academic/artistic)abstract
- The monitoring of phenolic compounds in raw waters and wastewaters is of great importance for environmental control. Use of biosensors for rapid, specific and simple detection of phenolic compounds is a promising approach. A number of biosensors have been developed for phenol detection. A general drawback of previously reported biosensors is their insufficient detection limits for phenols in water samples. One way to improve the detection limit is by the use of microelectrodes.Microband design of the microelectrodes combines convergent mass transport due to the microscale width and high output currents due to the macroscopic length. Among the various techniques available for microband electrode fabrication, we have chosen screen-printing which is a cost-effective production method.In this study, we report on the development of a laccase-based microscale biosensor operating under a convergent diffusion regime. Screen-printing followed by simple cutting was utilized for the fabrication of graphite microbands as a platform for further covalent immobilization of laccase. Numerical simulations, utilizing the finite element method with periodic boundary conditions, were used for modeling the voltammetric response of the developed microband electrodes. Anodization followed by covalent immobilization was used for the electrode modification with laccase. Direct and mediated laccase bioelectrocatalytic oxidation of phenols was studied on macro- and microscale graphite electrodes. Significant enhancement of the analytical performance was achieved by the establishment of convergent diffusion in the microscale sensor. Finally, the developed microsensor was utilized to monitor phenolic compounds in real waste water.
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| 7. |
- Sekretaryova, Alina N., et al.
(author)
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Electrocatalytic Currents from Single Enzyme Molecules
- 2016
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:8, s. 2504-2507
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Journal article (peer-reviewed)abstract
- Single molecule enzymology provides an opportunity to examine details of enzyme mechanisms that are not distinguishable in biomolecule ensemble studies. Here we report, for the first time, detection of the current produced in an electrocatalytic reaction by a single redox enzyme molecule when it collides with an ultramicroelectrode. The catalytic process provides amplification of the current from electron-transfer events at the catalyst leading to a measurable current. This new methodology monitors turnover of a single enzyme molecule. The methodology might complement existing single molecule techniques, giving further insights into enzymatic mechanisms and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.
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| 8. |
- Sekretaryova, Alina, et al.
(author)
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Unsubstituted phenothiazine as a superior water-insoluble mediator for oxidases
- 2014
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In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 53, s. 275-282
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Journal article (peer-reviewed)abstract
- The mediation of oxidases glucose oxidase (GOx), lactate oxidase (LOx) and cholesterol oxidase (ChOx) by a new electron shuttling mediator, unsubstituted phenothiazine (PTZ), was studied. Cyclic voltammetry and rotating-disk electrode measurements in nonaqueous media were used to determine the diffusion characteristics of the mediator and the kinetics of its reaction with GOx, giving a second-order rate constant of 7.6×103–2.1×104 M−1 s−1 for water–acetonitrile solutions containing 5–15% water. These values are in the range reported for commonly used azine-type mediators, indicating that PTZ is able to function as an efficient mediator. PTZ and GOx, LOx and ChOx were successfully co-immobilised in sol–gel membrane on a screen-printed electrode to construct glucose, lactate and cholesterol biosensors, respectively, which were then optimised in terms of stability and sensitivity. The electrocatalytic oxidation responses showed a dependence on substrate concentration ranging from 0.6 to 32 mM for glucose, from 19 to 565 mM for lactate and from 0.015 to 1.0 mM for cholesterol detection. Oxidation of substrates on the surface of electrodes modified with PTZ and enzyme membrane was investigated with double-step chronoamperometry and the results showed that the PTZ displays excellent electrochemical catalytic activities even when immobilised on the surface of the electrode.
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| 9. |
- Vagin, Mikhail Yu., et al.
(author)
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Water-processable polypyrrole microparticle modules for direct fabrication of hierarchical structured electrochemical interfaces
- 2016
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In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 190, s. 495-503
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Journal article (peer-reviewed)abstract
- Hierarchically structured materials (HSMs) are becoming increasingly important in catalysis, separation and energy applications due to their advantageous diffusion and flux properties. Here, we introduce a facile modular approach to fabricate HSMs with tailored functional conducting polypyrrole microparticles (PPyMP). The PPyMPs were fabricated with a calcium carbonate (CaCO3) template-assisted polymerization technique in aqueous media at room temperature, thus providing a new green chemistry for producing water-processable functional polymers. The sacrificial CaCO3 template guided the polymerization process to yield homogenous PPyMPs with a narrow size distribution. The porous nature of the CaCO3 further allows the incorporation of various organic and inorganic dopants such as an electrocatalyst and redox mediator for the fabrication of functional PPyMPs. Dawson-type polyoxometalate (POM) and methylene blue (MB) were chosen as the model electrocatalyst and electron mediator dopant, respectively. Hierarchically structured electrochemical interfaces were created simply by self-assembly of the functional PPyMPs. We demonstrate the versatility of this technique by creating two different hierarchical structured electrochemical interfaces: POM-PPyMPs for hydrogen peroxide electrocatalysis and MB-PPyMPs for mediated bioelectrocatalysis. We envision that the presented design concept could be extended to different conducting polymers doped with other functional organic and inorganic dopants to develop advanced electrochemical interfaces and to create high surface area electrodes for energy storage.
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| 10. |
- Zhybak, Mykhailo T., et al.
(author)
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Direct detection of ammonium ion by means of oxygen electrocatalysis at a copper-polyaniline composite on a screen-printed electrode
- 2016
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In: Microchimica Acta. - : Springer Science and Business Media LLC. - 0026-3672 .- 1436-5073. ; 183:6, s. 1981-1987
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Journal article (peer-reviewed)abstract
- We describe a composite material for use in electrochemical oxygen reduction. A screen-printed electrode (SPE) was consecutively modified with electrodeposited copper, a Nafion membrane and electropolymerized polyaniline (PANi) to give an electrocatalytic composite of type PANi/Nafion/Cu2O/SPE that displays good electrical conductivity at neutral pH values. It is found that the presence of ammonia causes complex formation with Cu(I), and this causes electroreduction of oxygen to result in an increased cathodic current. The finding was applied to the quantification of ammonium ions in the 1 to 1000 μM concentration range by amperometry at −0.45 V (vs. Ag/AgCl). This Faradaic phenomenon offers the advantage of direct voltammetric detection, one of the lowest known limits of detection (0.5 μM), and high sensitivity (250 mA∙M−1∙cm−2). It was applied to the determination of ammonium ion in human serum where it compared well with the photometric routine approach for clinical analysis using glutamate dehydrogenase. [Figure not available: see fulltext.]
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