bluuebunny/crossref_metadata_2025_split huggingface dataset:
Volume and Enthalpy Changes upon Photoexcitation of Bovine Rhodopsin Derived from Optoacoustic Studies by Using an Equilibrium between Bathorhodopsin and Blue‐Shifted Intermediate
Authors: Gensch Thomas , Strassburger Julia M. , Gärtner Wolfgang , Braslavsky Silvia E. 
Published: November 2013

AbstractA complex multistep model including an equilibrium was used for the first time to analyze data obtained by laser‐induced optoacoustic spectroscopy (LIOAS) with bovine rhodopsin in washed membranes (T = 5–32°C). The thermal equilibrium was between bathorhodopsin, batho, and the blue‐shifted intermediate (BSI), i.e., batho ⇄ BSI. This analysis considers a 14‐ns intermediate detected by LIOAS at 25°C (with similar decay activation parameters as those reported for BSI in solubilized rhodopsin). The energy content of lumirhodopsin (lumi) and the structural volume difference between lumi and rhodopsin were essentially the same (Elumi. = 80 kJ/mol and ΔVlumi–rho = 40 mL/mol) for both a model based on a simple batho → BSI → lumi sequence and one including the batho ⇄; BSI equilibrium. However, the structural volume changes for the individual steps batho → BSI and BSI → lumi were markedly changed by the introduction of the equilibrium. With the rate constant for the forward reaction batho → BSI for solubilized rhodopsin determined by Hug et al. (Hug, S.J.; Lewis, W.J.; Einterz, C.M.; Thorgeirsson, T.E.; Kliger, D.S. Biochemistry, 1990, 29, 1475–1485) the structural volume changes obtained with the equilibrium model are ΔVBSI‐batho = 79 mL/mol and ΔVlumi‐BSI = −44 mL/mol. The resulting batho → BSI expansion is larger than with the sequential model, and ΔVlumi‐BSI is now a contraction instead of an expansion. A small expansion of 5 mL/mol is derived for the formation of batho with both models. The estimated energy content of BSI is clearly higher than the value of lumi. The structural volume changes between batho, BSI, and lumi derived from the equilibrium model correlate better than those from the simple sequential model with the chromophore transition dipole moment changes determined in the literature using linear dichroism measurements. The structural volume changes are discussed in terms of the variations upon transformation of the chromophore–protein interactions.
Wavelength Dependence of the Quantum Yield of Charge Separation in Photosynthesis: Photoacoustic Study of Light Energy Distribution among Various Pigment Complexes
Authors: Delosme René 
Published: November 2013

AbstractThe quantum yield spectra of photochemical charge separation have been measured in different photosynthetic materials [whole cells of wild type and mutant strains of green algae, photosystem I (PSI) and photosystem II (PSII) purified complexes, isolated photosynthetic membranes from plants (thylakoids), plant leaves] in the whole range of visible light, using a photoacoustic spectrometer previously described and slightly improved. The photochemical activity was sampled in dark‐adapted material by a monochromatic laser flash of very low energy, i.e., under conditions where the concentration of open reaction centers was maximal. The efficiency of energy conversion by the different pigment‐protein complexes is discussed on the basis of the quantum yield spectra. The respective contributions of PSI and PSII were measured in two distinct states (known as states 1 and 2) of energy distribution to the photosystems. In both states, light absorbed by the PSI antenna as a whole was found to be more efficient than that absorbed by the PSII antenna. Although in state 1 light energy is almost equally distributed amongst the two photosystems at 680 nm, about one‐third of the light absorbed by PSII at this wavelength is not used for photochemistry under the conditions of our study. Under state 2 conditions in Chlamydomonas reinhardtii, the antenna size of PSI is considerably increased at the expense of PSII, and the quantum yield difference spectrum corresponding to the “mobile” antenna clearly identifies light‐harvesting complex II (LHCII).The quantum yield spectra measured in the region of light absorption by carotenoids favor the view that the xanthophylls of the peripheral antenna (especially lutein in LHCII) have an efficient light‐harvesting function, in contrast to β‐carotene which acts probably as a protective energy trap in the core complexes.
Probing Electron Transport through and around Photosystem II in vivo by the Combined Use of Photoacoustic Spectroscopy and Chlorophyll Fluorometry
Authors: Havaux Michel 
Published: November 2013

AbstractPhotoacoustic spectroscopy and chlorophyll fluorometry were used in combination to monitor in vivo several aspects of the photosystem II (PSII) function (O2 evolution, electron transport, and energy storage) in leaves of various plant genotypes. Exposure of barley leaves to 45°C in low light induced a rapid and complete disruption of the O2‐evolving complex of PSII, as shown by the suppression of the photobaric component of the photoacoustic signal. The photoacoustically measured loss of O2 evolution during heat stress (i) was confirmed by polarographic measurements of O2 exchange by the leaf samples, (ii) was shown to be independent of the activity of the carbonic anhydrase, and (iii) was not correlated with a concomitant suppression of the photochemical energy storage and the electron transport activity of PSII. The maintenance of a significant PSII photochemical activity in the absence of O2 evolution is indicative of cyclic electron transport around PSII which bypasses the O2‐evolving complex. The modulation‐frequency dependence of the energy stored during cyclic PSII activity, its inhibition by the herbicide diuron, and its insensitivity to the plastoquinol antagonist DBMIB (2,5‐dibromo‐3‐methyl‐6‐isopropyl‐p‐benzoquinone) indicated that QB, the secondary electron acceptor of PSII, is involved in the electron cycle and that the rate‐limiting step of the cycle is a reaction with a half‐time of ca. 1.5 ms. In the absence of heat stress, overreduction of the plastoquinone pool by strong illumination or by leaf infiltration with DBMIB was not sufficient to induce appreciable cyclic electron transport around PSII. The electron cycle was insensitive to preferential excitation of carotenoids with a blue‐green light and was not significantly affected by the operation of the xanthophyll cycle. Interruption of the electron cycle by diuron during prolonged heat treatment in moderate light was accompanied by a marked peroxidation of the chloroplast thylakoid membranes, as revealed by the appearance of chlorophyll thermoluminescence bands in the temperature range 70–120°C, demonstrating the photoprotective function of electron cycling around PSII.
Structure–Activity Correlations for Au Nanoclusters Supported on TiO2
Authors: Valden Mika , Goodman D. Wayne 
Published: November 2013

AbstractThe catalytic performance of reducible metal‐oxide‐supported Au nanoclusters displays striking dependencies on several factors such as dispersion, support, pretreatment, and preparation methods. Planar model Au/TiO2 catalysts have been prepared in ultrahigh vacuum in order to investigate the strong size dependence of low‐temperature CO oxidation. It is demonstrated that the experimentally observed structure sensitivity of CO oxidation on Au/TiO2 may be rationalized by a quantum size effect. Via scanning tunneling microscopy and spectroscopy (STM/STS) and elevated pressure reaction kinetics measurements, we show that a clear correlation exists between the structural, electronic, and reactivity properties of supported Au nanoclusters.
Effect of Mixing on Natural Gas Reburning
Authors: Zamansky Vladimir M. , Lissianski Vitali V. 
Published: November 2013

AbstractThe purpose of this work is to understand the influence of the mixing process on reburning performance. Modeling is done in a one‐dimensional approximation by utilizing a detailed chemical mechanism, staged addition of reactants, and mixture stratification. Natural gas is used as both the main fuel and the reburning fuel. The most important parameters that affect the efficiency of the reburning process are: the amount of the reburning fuel, the initial NO level, the initial temperatures of the injected reburning fuel and overfire air (OFA), temperature of flue gas at the points where reburning fuel and OFA are injected, and intensity of mixing of the reburning fuel and OFA with the stream of flue gases. It is shown that fuel stratification in the mixing zone improves reburning efficiency for small heat inputs of the reburning fuel and degrades reburning efficiency for large heat inputs. Initial temperatures of the reburning fuel and OFA affect NO reduction and can be optimized for deeper NO control. Reactions of N‐containing species in the burnout zone play an important role in NO reduction for large heat inputs of the reburning fuel.
Unusual Reaction of N‐Arylimines of Hexafluoroacetone with m‐Chloroperoxybenzoic Acid. New Route to 2,2‐Bis(trifluoromethyl)benzoxazolidines
Authors: Petrov Viacheslav A. , Khasnis Dipti D. 
Published: November 2013

AbstractReaction of readily available N‐arylimines of hexafluoroacetone with anhydrous m‐chloroperoxybenzoic acid leads to the formation of substituted 2,2‐bis(trifluoromethyl)oxazolidines in 30–70% yield as a result of an oxidative cyclization reaction. This process is general and can be used as a synthetic route to the corresponding polyfluorinated oxazolidines.
Study of the Effect of Fluorine Atom(s) on Fluoromethylated Imines in the Tandem Mannich–Michael‐type Reaction
Authors: Murata Kouichi , Kitazume Tomoya 
Published: November 2013

AbstractDifferences in chemical behavior between non‐fluorinated and fluorinated methylimines in the tandem Mannich–Michael‐type reaction are described based on NMR and computational studies.
CuCN and Trimethylsilyl Chloride‐Catalyzed Regiospecific Grignard Reactions to CF3‐Containing Allylic Derivatives
Authors: Yamazaki Takashi , Umetani Hideki , Kitazume Tomoya 
Published: November 2013

AbstractCF3‐containing allylic alcohol derivatives were treated with an appropriate Grignard reagent in the presence of catalytic amounts of CuCN and trimethylsilyl chloride (TMSCl) to furnish products via the cleananti‐SN2′ mechanism. Experimental results as well as ab initio computational analyses unambiguously demonstrated the important roles of TMSCl as a Lewis basic additive for smooth promotion of reductive elimination and inhibition of the “Cu···F” elimination leading to undesired byproduct formation.
Proton Transfer Processes in Water Clusters
Authors: Bondybey Vladimir E. , Beyer Martin , Achatz Uwe , Joos Stefan , Niedner‐Schatteburg Gereon 
Published: November 2013

AbstractElucidation of some of the basic mechanisms and principles of proton transfer in clusters is achieved by systematic evaluation of experimental and theoretical results that were obtained throughout the last decade from the authors' studies on ionic water clusters and, more recently, on protonated rare gas clusters. Among the processes studied are: Blackbody radiation‐induced, stepwise desolvation of clusters when stored in an ion trap; ionic dissociation and recombination of HCl in water clusters; metal oxidation in aqueous clusters; formation of nascent hydrogen in reactions of solvated metal cations with acids; and the behavior of ionic water clusters as acidic or basic micro‐solutions. Infrared spectroscopic studies of size‐selected water clusters are expected to advance our knowledge of structure and dynamics of water clusters and of excess protons therein.
Diffraction Studies on Concentrated Aqueous Hydrochloric Acid Solutions
Authors: Kameda Yasuo , Usuki Takeshi , Uemura Osamu 
Published: November 2013

AbstractX‐ray diffraction and neutron diffraction experiments with H/D isotopically substituted aqueous 21 mol% hydrochloric acid solutions were carried out in order to obtain detailed features concerning the intermolecular hydrogen‐bonded structure in highly concentrated aqueous acidic solutions. Structure parameters, namely, intermolecular distance, root‐mean‐square amplitude, and coordination number, for the nearest neighbor H3O+···H2O interaction were determined from the least‐squares‐fitting analysis of the observed X‐ray interference term. These were, respectively, r(H3O+···H2O) = 2.45(1) Å; l(H3O+···H2O) = 0.11(1) Å; and n(H3O+···H2O) = 1.8(1). The intermolecular nearest neighbor distances, r(H···H) = 2.02(5) Å and r(O···H) = 1.69(2) Å, were determined from the least‐squares fit to partial structure factors, aij (Q), derived from the observed neutron intermolecular interference terms for sample solutions with different H/D isotopic ratios. The present values of intermolecular distances are significantly shorter than those for pure liquid water, implying that extremely strong hydrogen bonds exist in concentrated aqueous acidic solutions.
Flying Protons in Linked Gramicidin A Channels
Authors: Cukierman Samuel 
Published: November 2013

AbstractDifferent lines of evidence indicate that the mobility of protons in gramicidin A (gA) channels as well as in its SS dioxolane linked dimer (SS dimer) is comparable to the proton mobility in aqueous HCl solutions. Single‐channel proton conductances in the SS dimer were measured under different experimental conditions. Bulk conductivities of HCl solutions were also measured. Ratios between calculated proton mobilities in the SS dimer and in aqueous solutions varied between 0.75 and 0.10 in the HCl concentration range of 10–6000 mM. Proton mobility in the SS dimer is profoundly affected by the lipid composition of the membrane. Attenuation of proton conduction in the SS dimer and in solution by methanol have similar characteristics. It is proposed that methanol partitions inside the pore of the SS dimer and attenuates proton conductance.
Proton Binding Is Part of Protein Relaxation of Flash‐Excited Reaction Center from Photosynthetic Bacteria Rhodobacter sphaeroides
Authors: Turzó Kinga , Laczkó Gábor , Maróti Péter 
Published: November 2013

AbstractIn the first part of this work, a brief review is presented of the recent knowledge of charge stabilization processes in flash‐excited reaction center protein from photosynthetic bacteria Rhodobacter sphaeroides. The adaptation of the protein to charge separation is comprised of different manifestations of protein relaxation including proton binding at the late phase. In the second part, a unique method, comparative measurement of prompt and millisecond‐delayed fluorescence of the bacteriochlorophyll dimer of the reaction center protein is used to determine the free energy levels of the charge‐separated states with respect to that of the excited singlet state of the dimer: −910 ± 20 meV and −970 ± 20 meV were measured at pH 8.0 for reaction centers in the absence and presence of secondary quinone, respectively. The pH‐dependence of the energetics of charge stabilization due to light‐induced proton binding is described in reaction centers with and without secondary quinone activity. The range of free‐energy change between pH 11 and pH 5 was −65 meV with a single (alkaline) inflection point (no active secondary quinone) and −175 meV with an additional (acidic) inflection point (active secondary quinone). The conclusions from fluorescence data agreed well with pH‐dependence of integrated proton uptake (a model‐independent method) and with calculations based on interaction of quinones with four key amino acid residues. The enthalpy and entropy parts of the free‐energy changes were determined from van't Hoff analysis of the delayed fluorescence and compared with data of other methods. It is concluded that the charge stabilization including proton binding is a highly enthalpy‐driven process.
The effect of sterilization methods on electronspun poly(lactide‐co‐glycolide) and subsequent adhesion efficiency of mesenchymal stem cells
Authors: Braghirolli Daikelly Iglesias , Steffens Daniela , Quintiliano Kerlin , Acasigua Gerson Arisoly Xavier , Gamba Douglas , Fleck Roland A. , Petzhold Cesar L. , Pranke Patricia 
Published: November 2013

AbstractThe sterilization of scaffolds is an essential step for tissue engineering in vitro and, mainly, clinical biomaterial use. However, this process can cause changes in the structure and surface of the scaffolds. Therefore, the objective of this study was to investigate the effect of sterilization by ethanol, ultraviolet radiation (UVR) or antimicrobial solution (AMS) on poly(lactide‐co‐glycolide) (PLGA) scaffolds produced by the electrospinning technique. The properties of nanofibers and the cellular adhesion of mesenchymal stem cells to the scaffolds were analyzed after the treatments. All methods generated sterile scaffolds but showed some kind of damage to the scaffolds. Ethanol and AMS caused changes in the morphology and scaffold dimensions, which were not observed when using the UVR method. However, UVR caused a greater reduction in polymeric molecular weight, which increased proportionally with exposure time of treatment. Nanofibers sterilized with AMS for 1 h and 2 h showed greater cellular adhesion than the other methods, demonstrating their potential as a method for sterilizing PLGA nanofibers. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 700–708, 2014.
A polycaprolactone/cuttlefish bone‐derived hydroxyapatite composite porous scaffold for bone tissue engineering
Authors: Kim Beom‐Su , Yang Sun‐Sik , Lee Jun 
Published: November 2013

AbstractCuttlefish bone (CB) is an attractive natural biomaterial source to obtain hydroxyapatite (HAp). In this study, a porous polycaprolactone (PCL) scaffold incorporating CB‐derived HAp (CB‐HAp) powder was fabricated using the solvent casting and particulate leaching method. The presence of CB‐HAp in PCL/CB‐HAp scaffold was confirmed by X‐ray diffraction (XRD). Scanning electron microscopy (SEM) and porosity analysis showed that the average pore dimension of the fabricated scaffold was approximately 200–300 μm, with ∼85% porosity, and that the compressive modulus increased after addition of CB‐HAp powders. In vitro tests such as cell proliferation assay, cytotoxicity analysis, cell attachment observations, and alkaline phosphatase activity assays showed that the PCL/CB‐HAp scaffold could improve the proliferation, viability, adherence, and osteoblast differentiation rate of MG‐63 cells. When surgically implanted into rabbit calvarial bone defects, consistent with the in vitro results, PCL/CB‐HAp scaffold implantation resulted in significantly higher new bone formation than did implantation of PCL alone. These findings suggest that addition of CB‐HAp powder to the PCL scaffold can improve cellular response and that the PCL/CB‐HAp composite scaffold has great potential for use in bone tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 943–951, 2014.
Retrospective evaluation of exposure index (EI) values from plain radiographs reveals important considerations for quality improvement
Authors: Mothiram Ursula , Brennan Patrick C. , Robinson John , Lewis Sarah J. , Moran Bernadette 
Published: November 2013

AbstractIntroductionFollowing X‐ray exposure, radiographers receive immediate feedback on detector exposure in the form of the exposure index (EI).PurposeTo identify whether radiographers are meeting manufacturer‐recommended EI (MREI) ranges for routine chest, abdomen and pelvis X‐ray examinations under a variety of conditions and to examine factors affecting the EI.MethodsData on 5000 adult X‐ray examinations including the following variables were collected: examination parameters, EI values, patient gender, date of birth, date and time of examination, grid usage and the presence of implant or prosthesis. Descriptive statistics were used to summarize each data set and the Mann–Whitney U test was used to determine significant differences, with P < 0.05 indicating significance for all tests.ResultsMost examinations demonstrated EI values that were outside the MREI ranges, with significantly higher median EI values recorded for female patient radiographs than those for male patients for all manufacturers, indicating higher detector exposures for all units except for Philips digital radiography (DR), where increased EI values indicate lower exposure (P = 0.01). Median EI values for out of hours radiography were also significantly higher compared with normal working hours for all technologies (P ≤ 0.02). Significantly higher median EI values were demonstrated for Philips DR chest X‐rays without as compared to those with the employment of a grid (P = 0.03), while significantly lower median EI values were recorded for Carestream Health computed radiography (CR) chest X‐rays when an implant or prosthesis was present (P = 0.02).ConclusionsNon‐adherence to MREIs has been demonstrated with EI value discrepancies being dependent on patient gender, time/day of exposure, grid usage and the presence of an implant or prosthesis. Retrospective evaluation of EI databases is a valuable tool to assess the need of quality improvement in routine DR.
The Use of Radio Frequency Identification Technology in Packaging Systems: Experimental Research on Traceability
Authors: Regattieri Alberto , Santarelli Giulia , Gamberi Mauro , Gamberini Rita 
Published: November 2013

This paper focuses on the analysis of the internal flow traceability of goods (products and/or packages) along the supply chain by Radio Frequency IDentification (RFID) technology.Traditionally, the traceability system is performed through the asynchronous fulfilment of checkpoints (i.e. doorways) by materials. In such cases, the tracking is manual, executed by operators that manually trace the path. Often, companies are not aware of the inefficiencies because of these traceability systems such as low precision and accuracy in measurements (i.e. no information between doorways), more time spent by operators and costs (due to the full effort of operators who have to search for the good positions and movements). In order to overcome these limitations, automatic identification procedures have been introduced in many service industries, purchasing and distribution logistics, manufacturing companies and material flow systems. Automatic identification procedures can also be applied to the packaging of products, instead of to each item contained in the package. Sometimes, products are very expensive, and packages contain important and critical goods (e.g. dangerous or explosive materials); thus, the tracking of goods – and packages in particular – is a critical function.In order to analyse the traceability of the packaging system, the authors have developed an innovative system based on Radio Frequency IDentification‐Ultra Wide Band (RFID‐UWB) technology. A prototype of this system has been realized and used for an experimental research that has consisted of several tests (static and dynamic), tracing the position (static) and movements (dynamic) of products and in particular packages in indoor environments, in continuous and in real time. Copyright © 2013 John Wiley & Sons, Ltd.
Comparison of factors affecting the accuracy of high‐precision magnesium isotope analysis by multi‐collector inductively coupled plasma mass spectrometry
Authors: Teng Fang‐Zhen , Yang Wei 
Published: November 2013

RATIONALEHigh accuracy is the prerequisite for high‐precision isotopic analysis.METHODSHere we evaluate how the presence of matrix elements, and mismatch between samples and standards in Mg concentration and acid molarity affect the accuracy of stable Mg isotopic analysis on Nu Plasma and IsoProbe multi‐collector inductively coupled plasma mass spectrometry (MC‐ICPMS) instruments.RESULTSOur results show that these factors can lead to large (>1‰) deviation in the high‐precision analysis of Mg isotopes. The degree and direction of these accuracy offsets can vary for different instruments, instrumental settings and different laboratories.CONCLUSIONSDetailed tests and tight controls on these effects are thus needed for high‐precision high‐accuracy stable Mg isotopic analysis. Copyright © 2013 John Wiley & Sons, Ltd.