662 research outputs found
Garbage in the diet of carnivores in an agricultural area
Human food waste is considered to be richer in carbohydrates, lipids and proteins than most natural food supplies; however, it is very well digested in scats. So, as an indication of this kind of food in the diet, we have used each indigestible, anthropogenic origin element found in faeces (e.g., glass, plastic, rubber, etc.). There are few studies discussing the importance of garbage in the diet of mammalian predators living in farmland; definitely, most focus on this issue in urban areas. We studied the contribution of garbage in the diet of raccoon dog (Nyctereutes procyonoides), red fox (Vulpes vulpes), marten (Martes sp.), polecat (Mustela putorius), stoat (Mustela erminea), American mink (Neovison vison) and Eurasian otter (Lutra lutra) in the agricultural areas of western Poland in 2006-2010. In addition, we examined the spatial changes in the diet of red fox and polecat. The largest contribution of garbage was found in scats of raccoon dog (8.8%), red fox (4.8%) and marten (4.3%). The diet of polecat, stoat and Eurasian otter contained 2.5%, 1.7% and 0.2% garbage items respectively. The most frequent item was plastic. Our analysis showed that garbage consumption by red fox and polecat was greater closer to human settlements. The results reveal a continuous gradient in the garbage consumption that corresponds with the degree of synanthropization of particular species
Capillary electrophoresis-fluorescence line narrowing system (CE-FLNS) for on-line structural characterization
Capillary electrophoresis (CE) is interfaced with low temperature fluorescenceline-narrowing (FLN) spectroscopy for on-line structural characterization of separated molecular analytes
Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers
Citation: Reppert, M., Kell, A., Pruitt, T., & Jankowiak, R. (2015). Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers. Journal of Chemical Physics, 142(9), 7. doi:10.1063/1.4913685The vibrational spectral density is an important physical parameter needed to describe both linear and non-linear spectra of multi-chromophore systems such as photosynthetic complexes. Low-temperature techniques such as hole burning (HB) and fluorescence line narrowing are commonly used to extract the spectral density for a given electronic transition from experimental data. We report here that the lineshape function formula reported by Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] in the mean-phonon approximation and frequently applied to analyzing HB data contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(omega) is given that retains the computational and intuitive advantages of the expression of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)]. Although the corrected lineshape function could be used in modeling studies of various optical spectra, we suggest that it is better to calculate the lineshape function numerically, without introducing the mean-phonon approximation. New theoretical fits of the P870 and P960 absorption bands and frequency-dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers are provided as examples to demonstrate the importance of correct lineshape expressions. Comparison with the previously determined el-ph coupling parameters [Johnson et al., J. Phys. Chem. 94, 5849 (1990); Lyle et al., ibid. 97, 6924 (1993); Reddy et al., ibid. 97, 6934 (1993)] is also provided. The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker mode, omega(sp), for Rb. sphaeroides that could be used in the future for more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers. (c) 2015 AIP Publishing LLC
Various Improvements to Operate the 1.5GeV HDSM at MAMI
During the last three years at the 1.5GeV Harmonic Double Sided Microtron HDSM, [1] of MAMI a lot of improvements concerning the longitudinal operation of the accelerator were tested and installed. To monitor the rf power dissipated in the accelerating sections, their cooling water flow and its temperature rise are now continuously logged. Phase calibration measurements of the linacs and the phase intensity monitors p i monitors revealed nonlinearities of the high precision step motor driven waveguide phase shifters. They were recalibrated to deliver precise absolute values. Thereby it is now possible to measure not only the first turn s phase very exactly, but also to determine the linac s rf amplitude within an error of less than 5 using the well known longitudinal dispersion of the bending system. These results are compared to the thermal load measurements. For parity violation experiments the beam energy has to be stabilised to some 10 amp; 8722;6. A dedicated system measuring the time of flight through a bending magnet is now used in routine operation and controls the output energy via the linac phase
Site Energies of Active and Inactive Pheophytins in the Reaction Center of Photosystem II from Chlamydomonas Reinhardtii
31 Pags. The definitive version is available at: http://pubs.acs.org/journal/jpcbfkIt is widely accepted that the primary electron acceptor in various Photosystem II (PSII) reaction centers (RCs) is pheophytin a (Pheo a) within the D1 protein (PheoD1), while PheoD2 (within the D2 protein) is photochemically inactive. The Pheo site energies, however, have remained elusive, due to inherent spectral congestion. While most researchers over the last two decades assigned the Qy-states of PheoD1 and PheoD2 bands near 678â684 nm and 668â672 nm, respectively, recent modeling [Raszewski et al. Biophys. J. 2005, 88, 986â998; Cox et al. J. Phys. Chem. B 2009, 113, 12364â12374] of the electronic structure of the PSII RC reversed the location of the active and inactive Pheos, suggesting that the mean site energy of PheoD1 is near 672 nm, whereas PheoD2 (~677.5 nm) and ChlD1 (~680 nm) have the lowest energies (i.e., the PheoD2-dominated exciton is the lowest excited state). In contrast, chemical pigment exchange experiments on isolated RCs suggested that both pheophytins have their Qy absorption maxima at 676â680 nm [Germano et al. Biochem. 2001, 40, 11472â11482; Germano et al. Biophys. J. 2004, 86, 1664â1672]. To provide more insight into the site energies of both PheoD1 and PheoD2 (including the corresponding Qx transitions, which are often claimed to be degenerate at 543 nm) and to attest that the above two assignments are most likely incorrect, we studied a large number of isolated RC preparations from spinach and wild-type Chlamydomonas reinhardtii (at different levels of intactness) as well as the Chlamydomonas reinhardtii mutant (D2-L209H), in which the active branch PheoD1 is genetically replaced with chlorophyll a (Chl a). We show that the Qx-/Qy-region site-energies of PheoD1 and PheoD2 are ~545/680 nm and ~541.5/670 nm, respectively, in good agreement with our previous assignment [Jankowiak et al. J. Phys. Chem. B 2002, 106, 8803â8814]. The latter values should be used to model excitonic structure and excitation energy transfer dynamics of the PSII RCs.Partial support to B.N. (involved in calculations) was provided by the NSF
EPSCoR Grant. V.Z. (involved in writing the manuscript) acknowledges support by NSERC.
R.T.S., R.P., and M.S. were involved in the design and preparation of D2-mutant and RCs. They
acknowledge support from USDOE, Photosynthetic Antennae Research Center (R.T.S.), MICIN
(Grant AGL2008-00377) in Spain (R.P.), and the U.S. Department of Energyâs Photosynthetic
Systems Program within the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences under NREL Contract #DE-AC36-08-GO28308 (M.S.).Peer reviewe
The Injector Layout of BERLinPro
BERLinPro is an Energy Recovery Linac Project running since 2011 at the HZB in Berlin. A conceptual design report has been published in 2012 [1]. One of the key components of the project is the 100 mA superconducting RF photocathode gun under development at the HZB since 2010. Starting in 2016 the injector will go into operation, providing 6.6 MeV electrons with an emittance well below 1mm mrad and bunches shorter than 5 ps. In 2017 the 50 MeV linac will be set up and full recirculation is planned for 2018. The injector design has been finalized and is described in detail in this paper. Emphasis is further laid on beam dynamics aspects and performance simulations of two different gun cavitie
LOOKING INTO THE ENERGY LANDSCAPE OF MYOGLOBIN
Using the haem group of myoglobin as a probe in optical experiments makes it possible to study its conformational fluctuations in real time. Results of these experiments can be directly interpreted in terms of the structure of the potential energy surface of the protein. The current view is that proteins have rough energy landscapes comprising a large number of minima which represent conformational substates, and that these substates are hierarchically organized. Here, we show that the energy landscape is characterized by a number of discrete distributions of;barrier heights each representing a tier within a hierarchy of conformational substates. Furthermore, we provide evidence that the energy surface is self-similar and offer suggestions for a characterization of the protein fluctuations
The CP43 Proximal Antenna Complex of Higher Plant Photosystem II Revisited: Modeling and Hole Burning Study. I
The final version is available at:
http://pubs.acs.org/journal/jpcbfkThe CP43 core antenna complex of photosystem II is known to possess two quasi-degenerate âredâ-trap states (Jankowiak, R. et al. J. Phys. Chem. B 2000, 104, 11805). It has been suggested recently ( Zazubovich, V.; Jankowiak, R. J. Lumin. 2007, 127, 245) that the site distribution functions of the red states (A and B) are uncorrelated and that narrow holes are burned in the subpopulations of chlorophylls (Chls) from states A and B that are the lowest-energy Chl in their complex and previously thought not to transfer energy. This model of uncorrelated excitation energy transfer (EET) between the quasidegenerate bands is expanded by taking into account both electronâphonon and vibrational coupling. The model is applied to fit simultaneously absorption, emission, zero-phonon action, and transient hole burned (HB) spectra obtained for the CP43 complex with minimized contribution from aggregation. It is demonstrated that the above listed spectra can be well-fitted using the uncorrelated EET model, providing strong evidence for the existence of efficient energy transfer between the two lowest energy states, A and B (either from A to B or from B to A), in CP43. Possible candidate Chls for the low-energy A and B states are discussed, providing a link between CP43 structure and spectroscopy. Finally, we propose that persistent holes originate from regular NPHB accompanied by the redistribution of oscillator strength due to excitonic interactions, rather than photoconversion involving Chlâprotein hydrogen bonding, as suggested before (Hughes J. L. et al. Biochemistry 2006, 45, 12345). In the accompanying paper ( Reppert, M.; Zazubovich, V.; Dang, N. C.; Seibert, M.; Jankowiak, R. J. Phys. Chem. B 2008, 9934), it is demonstrated that the model discussed in this manuscript is consistent with excitonic calculations, which also provide very good fits to both transient and persistent HB spectra obtained under non-line-narrowing conditions.This work was supported by the start-up funding at the Department of Chemistry, Kansas State University (RJ, NCD, MR and BN), and in part by the U.S. Department of Energy (DOE) EPSCoR grant (RJ), Energy Biosciences Program, Basic Energy Sciences, DOE (MS and NCD) and BFU2005-07422-CO2-01; Spain (RP). VZ acknowledges support by NSERC.Peer reviewe
Field Emission Studies of Heat Treated Mo Substrates
Molybdenum can be used as a substrate for the bi alkali antimonide photocathodes utilized for the generation of high brightness electron beams in a superconducting radio frequency SRF photoinjector cavities. Operation at high field strength is required to obtain a low emittance beam, thus increasing the probability of field emission FE from the cathode surface. Usually, substrates are heated in situ before alkali de position to remove oxide layers from the surface. FE on Mo substrates was measured by means of a field emission scanning microscope FESM . It turned out that in situ heat treatment HT of the Mo surface significantly changes the FE behaviour by activation of new emitters. For a better understanding of the mechanism for enhanced emission after in situ heating a witness Mo sample was investigated using x ray photoelectron spectroscop
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