bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromatography of Membrane Proteins and Lipoproteins
Authors: Zolla Lello , D'Alessandro Angelo 
Published: September 2011

AbstractThe available methods for the separation of membrane proteins and lipoproteins are sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE), followed by immunoblotting, isoelectric focusing (IEF), and capillary electrophoresis (CE), along with the recently introduced gel‐based native techniques (blue native (BN) and clear native (CN)), and high‐performance liquid chromatography (HPLC). In this article, it is shown that HPLC techniques, given their wide versatility, relative ease of use, and high resolution, may be considered the most valuable tool for the characterization of virtually any hydrophobic protein. Application examples are described, and comparisons with other methods are discussed. Moreover, HPLC is not a destructive technique, and therefore, proteins, once separated, are available for further analytical investigations. Among these techniques, quantitative and qualitative analyses of the separated fractions can be obtained through other biophysical approaches, such as crystallography or structural spectroscopy. Most of these approaches require preliminary protein purification (90% or higher), which could be rapidly obtained through preliminary HPLC.
Quantitative and Qualitative Analysis of Posttranslationally Modified Proteins
Authors: Sharp Joshua S. 
Published: September 2011

Abstract
The majority of proteins are posttranslationally modified. Posttranslational modifications (PTMs) have been found to modify a wide variety of biological and biophysical properties, including structure, biophysical stability and dynamics, enzymatic activity, protein‐protein interactions, protein‐ligand interactions, and protein half‐life within the cell. Virtually every analytical technique that can be used to analyze proteins in general can and has been used to analyze posttranslationally modified proteins. A vast array of both enzymatic and nonenzymatic protein modifications have been identified and characterized, which can make comprehensive analyses of all possible modifications difficult. Owing to the enormous scope of this topic, this article focuses on the analytical techniques that are probably most broadly applicable and widely used for wide‐scale analyses of posttranslationally modified proteins, namely mass spectrometry (MS) coupled to various separations technologies. Some technical and experimental details on the analyses of three heavily studied classes of PTM have been provided — phosphorylation, N‐linked glycosylation, and nonenzymatic oxidation. While we will be using these three classes of modifications in order to provide focus to our discussion, we will attempt to use these specific examples to illustrate broadly applicable techniques, as well as issues that often lead to difficulties and conflict between the experimental designs required for thorough quantitative and qualitative analyses of posttranslationally modified proteins.
Hydrogen Exchange Mass Spectrometry for Conformational Analysis of Proteins
Authors: Engen John R. , Wales Thomas E. , Shi Xiaomeng 
Published: September 2011

Abstract
Proteins contain labile hydrogen atoms at the backbone amide positions. These hydrogens are in continuous exchange with hydrogen in surrounding solvent. By incubating proteins with an isotope of hydrogen, usually deuterium, this exchange process can be monitored experimentally. Because hydrogen exchange (HX) is a function of protein conformation and dynamics, the rate of HX reports on aspects of protein structure. One method for detection of exchange is mass spectrometry (MS), as proteins will increase in mass as deuteration proceeds. This article provides background on how and why hydrogens exchange, how the exchange is controlled by several parameters, and what measuring exchange is good for, and then gives a general overview of how to make these measurements with MS.
Introduction to Modeling High‐resolution Spectra
Authors: Western Colin M. 
Published: September 2011

Abstract
The basic ideas involved in the application of model Hamiltonians involving angular momentum operators to predict energy levels and transition intensities of various molecular systems are introduced. Such methods are essential for understanding many molecular systems, and are illustrated here with a few selected examples. These include two interacting nuclear spins, “forbidden” singlet–triplet transitions and the energy‐level patterns associated with Hund's cases (a)–(c) in a diatomic molecule.
High Accuracy Rotation — Vibration Calculations on Small Molecules
Authors: Tennyson Jonathan 
Published: September 2011

AbstractThe first‐principles calculation of the spectra of triatomic and increasingly tetratomic molecules is beginning to make a significant impact on high‐resolution spectroscopy as well as astrophysics and atmospheric physics. The variational nuclear motion methods combined with high accuracy ab initio electronic structure calculations can be used to make spectral predictions of increasing accuracy with very few a priori assumptions. This work is important for spectral analysis and is becoming particularly so for dipole transition intensities, which are often very difficult to obtain reliably from experiment but are essential for modeling and remote sensing. In addition, demands for very extended linelists covering several millions of transitions that are required to reproduce spectra of hot sources are best met using high‐quality theoretical models. High accuracy can only be obtained by explicitly considering the so‐called minor effects such as relativistic effects on the electronic motion and failure of the Born–Oppenheimer approximation. H3+and its isotopologues are discussed as a benchmark system for high‐accuracy calculations.
Rotational Spectroscopy of Complexes Containing Free Radicals
Authors: Endo Yasuki , Sumiyoshi Yoshihiro 
Published: September 2011

Abstract
The recent developments in rotational spectroscopy especially for studies of open‐shell complexes are discussed in this article. Fourier‐transform microwave (FTMW) spectroscopy and FTMW‐cm/mm‐wave double‐resonance spectroscopy were used for the studies reviewed in the article. The systems reviewed are simple atom–diatom systems with open‐shell diatom, such as OH, SH, and NO, and more complex atom–triatom and molecule–radical systems. Detailed intermolecular potential surfaces have been obtained for the atom–diatom systems, with analyses using a hindered‐free‐rotor model. On the other hand, it was found that analyses for normal rigid molecules could be used for other more complicated systems.
New Techniques in Microwave Spectroscopy
Authors: Shipman Steven T. , Pate Brooks H. 
Published: September 2011

Abstract

We discuss the design principles and performance of a true broadband chirped‐pulse Fourier transform microwave spectrometer capable of operation from 800 MHz to 18.5 GHz. This spectrometer utilizes recent advances in high‐speed digital electronics to both directly generate linear frequency sweeps spanning more than 10 GHz and to directly digitize the molecular free induction decay (FID). Signal averaging is performed in the time domain to improve the signal‐to‐noise ratio. This spectrometer has a number of capabilities that are well suited for studies on large‐molecule systems, including the ability to perform multiplexed Stark effect measurements and selective‐excitation microwave double‐resonance measurements. These characteristics are demonstrated using the molecule 1,2,2,2‐tetrafluoroethyl difluoromethyl ether (C
3
H
2
F
6
O, molecular weight 168 g mol
−1
, also known by its trade names of
suprane
or
desflurane
) as an example. The simultaneous use of multiple‐pulsed nozzles as well as the acquisition of multiple FIDs per valve pulse is also demonstrated in the context of strategies for increasing spectrometer sensitivity by 2 orders of magnitude.
High‐resolution Inner‐shell Photoionization, Photoelectron and Coincidence Spectroscopy
Authors: Miron Catalin , Morin Paul 
Published: September 2011

Abstract
This article gives an overview of high‐resolution photoionization, photoelectron, and coincidence spectroscopies of inner‐shell excited species of increasing complexity ranging from atoms to nanoparticles. The development and the routine use of soft X‐ray techniques is intimately related to the spectacular advances in instrumentation in the last twenty years. These concern not only the construction and operation of high‐performance soft X‐ray beamlines at several synchrotron radiation laboratories around the world but also the remarkable improvement in charged particle analyzers and detectors (detection efficiency, resolution) and the extensive use of multidimensional coincidence techniques that allows simultaneous acquisition and further correlation of several physical parameters. From the examples we have chosen to present, it is apparent that inner‐shell ionization studies are not limited anymore by the lifetime broadening effects and that a deep and unique insight into ultrafast dynamics is possible. Various examples are shown of both pure high‐resolution photoionization and electron spectroscopies together with more sophisticated techniques such as the electron–ion coincidence measurements with energy and angle resolution. A prospective view of the field is given in the end. In particular, the expectations from the next‐generation ultrahigh brilliance X‐ray sources such as energy recovery linacs or free electron lasers are briefly tackled.
Experimental Methods in Cation Spectroscopy
Authors: Willitsch Stefan 
Published: September 2011

AbstractThe spectroscopic study of molecular cations in the gas phase poses a range of challenges which are generally associated with their high chemical reactivity, the difficulties in producing sufficiently high number densities of the desired ion species in a spectrometer, and the limits on the particle densities imposed by the space‐charge effect. The present article provides an overview of different experimental techniques that have been developed over the past years to overcome these problems. The topics discussed include highly sensitive laser‐based spectroscopic methods (cavity ring‐down spectroscopy, frequency‐, velocity‐ and concentration‐modulation schemes, and various types of action spectroscopy), the production of internally cold samples of ions and the use of mass‐spectrometric methods to select the species of interest out of a mixed sample. Owing to these developments, the range of molecular cations amenable to a spectroscopic characterization has been extended considerably over the past years and now includes various types of cluster ions, protonated biomolecules, ionic carbon chains, and the ions of polycyclic aromatic hydrocarbons.
Doppler‐free Laser Spectroscopy
Authors: Demtröder Wolfgang 
Published: September 2011

AbstractThis article discusses several experimental techniques with Doppler‐free spectral resolution such as linear spectroscopy in collimated molecular beams and nonlinear spectroscopy in gas or vapor cells, using saturation spectroscopy, polarization spectroscopy, or multiphoton absorption. Optical cooling of atoms and molecules down to extremely low temperatures brings the Doppler width below the natural linewidth. Special double‐resonance schemes enable stabilization of atomic collision pairs and sub‐Doppler spectroscopy of molecules in very high‐vibrational levels. Finally, some techniques with a resolution below the natural linewidth are discussed.
2
D
‐Infrared Spectroscopy
Authors: Hamm Peter 
Published: September 2011

Abstract
The basic concepts of 2D spectroscopy are summarized from both the theoretical and the experimental points of view. The Feynman diagram formalism is introduced and applied to calculate 2D spectra. Spectroscopic Hamiltonians are used to describe intramolecular couplings such as excitonic coupling and Fermi resonances, and to predict their appearance in a 2D spectrum. Furthermore, Kubo's lineshape theory is applied to 2D spectroscopy to explain dephasing in the presence of solvent fluctuations. Finally, various experimental realizations of 2D spectroscopy are discussed with their advantages and disadvantages.
High‐resolution Photofragment Translational Spectroscopy using Rydberg Tagging Methods
Authors: Ashfold Michael N. R. , King Graeme A. , Nix Michael G. D. , Oliver Thomas A. A. 
Published: September 2011

Abstract

Photofragment translational spectroscopy (PTS) is a general and versatile technique for exploring the dynamics of gas‐phase molecular photodissociation processes, through measurement of the speeds and directions of the resulting atomic and molecular products. This article describes recent enhancements in the achievable kinetic energy resolution and then focuses on applications employing one particular high‐resolution variant of the technique, wherein H(D) atom photofragments are monitored by Rydberg tagging methods. Systems described range from small hydrides such as H
2
O, NH
3
, and C
2
H
2
to larger heteroaromatic molecules such as pyrrole and phenol. In the former cases, the achievable resolution allows observation of individual rovibrational quantum states of the radical partner, providing detailed insights into the forces acting during the dissociation process. This allows intimate contact with complementary ab initio and wave packet modeling studies, and accurate determination of bond strengths and related thermodynamic quantities. The density of possible product states increases rapidly for larger radical cofragments. PTS studies of several heteroaromatics point to the generality of prompt dissociation from
1
πσ* excited states, which manifests itself in remarkably mode specific fragmentation dynamics. The article concludes with a summary of complementary photofragmentation studies of hydride radicals and an anticipation of future activities in this field.
Design Guidelines For Conjugated Polymers With Light‐Activated Anticancer Activity
Authors: Xing Chengfen , Liu Libing , Tang Hongwei , Feng Xuli , Yang Qiong , Wang Shu , Bazan Guillermo C. 
Published: September 2011

AbstractMultifunctional materials that simultaneously provide therapeutic action and image the results provide new strategies for the treatment of various diseases. Here, it is shown that water soluble conjugated polymers with a molecular design centered on the polythiophene−porphyrin dyad are effective for killing neighboring cells. Following photoexcitation, energy is efficiently transferred from the polythiophene backbone to the porphyrin units, which readily produce singlet oxygen (1O2) that is toxic for the cells. Due to the light‐harvesting ability of the electronically delocalized backbone and the efficient energy transfer amongst optical partners, the polythiophene−porphyrin dyad shows a higher 1O2 generation efficiency than a small molecule analog. The fluorescent properties of these polymers can also serve to distinguish amongst living and dead cells. Polymers can be designed with folic acid grafted onto the polymer side chain that can specifically kill folate receptor‐overexpressed cells, thereby providing an important demonstration of anticancer specificity through molecular design.
Interphases in Graphene Polymer‐based Nanocomposites: Achievements and Challenges
Authors: Terrones Mauricio , Martín Olga , González María , Pozuelo Javier , Serrano Berna , Cabanelas Juan C. , Vega‐Díaz Sofía M. , Baselga Juan 
Published: September 2011

AbstractGraphene constitutes a two dimensional sp2 hybridized carbon material with outstanding electrical and mechanical properties. To date, novel methods for producing large quantities of graphene and its derivatives (doped or functionalized graphenes, nanoribbons and nanoplatelets) are emerging, and research dedicated to the fabrication of polymer nanocomposites using graphenes has started. In this Research News, we summarize the synthesis and properties of graphene and its derivatives, and provide an overview of the latest research dedicated to the fabrication of polymer composites for different applications, including mechanical, electrical, optical and thermal. Some of the recently fabricated composites exhibit outstanding properties, however, it is vital to understand the chemistry and physics of the interphases established between the polymer and the graphene surfaces. The challenges in the fabrication of super robust and highly conducting composites using graphenes are also discussed. It is believed that graphene‐based polymer composites will result in commercial products if their interphases and reactivity are carefully controlled.
Embryo developmental disruption during organogenesis produced by CF‐1 murine periconceptional alcohol consumption
Authors: Coll Tamara A. , Tito Leticia Perez , Sobarzo Cristian M.A. , Cebral Elisa 
Published: September 2011

AbstractThe aim was to study the control females (CF)‐1 mouse embryo differentiation, growth, morphology on embryonic E‐ and N‐cadherin expression at midgestation after periconceptional moderate alcohol ingestion. Adult female mice were exposed to 10% ethanol in drinking water for 17 days previous to and up to day 10 of gestation (ethanol‐exposed females, EF) and were compared with nonexposed CF. EF presented reduced quantities of E10 to E10.5 embryos, greater percentage of embryos at stages less than E7.5, reduced implantation site numbers/female, and increased resorptions compared with CF. EF‐embryo growth was significantly affected as evidenced by reduced cephalic and body sizes of E10 and E10.5 embryos (scanning electron microscopy) and decreased protein content of E10.5 embryos vs. CF embryos. A significantly higher percentage of EF‐E10‐10.5 embryos presented abnormal neural tube (NT) closure vs. the percentage of CF. E10 embryos from EF presented elevated tissue disorganization, pyknosis and nuclear condensation in somites, mesenchymal and neuroepithelial tissue. Immunohistochemical E‐ and N‐cadherin distribution patterns were similar in organic structures of E10 embryos between groups. However, western blot revealed that E‐ and N‐cadherin expression levels were significantly increased in EF‐derived embryos vs. controls. Perigestational ethanol consumption by CF‐1 mice induced significant damage in the organogenic embryogenesis by producing delayed differentiation, growth deficiencies, and increasing the frequency of NT defects. Ethanol exposure may disrupt cell–cell adhesion leading to upregulation of E‐ and N‐cadherin expression suggesting that deregulation of cell adhesion molecules could be involved in the disruption of embryo development at organogenesis in CF‐1 mouse. Birth Defects Res (Part B) 92:560–574, 2011.© 2011 Wiley Periodicals, Inc.
Flavanone Glycosides from Viscum coloratum and Their Inhibitory Effects on Osteoclast Formation
Authors: Han Na , Huang Ting , Wang Yi‐Chun , Yin Jun , Kadota Shigetoshi 
Published: September 2011

AbstractTwo novel flavanone glycosides, homoeriodictyol 7‐O‐β‐D‐[6‐(3‐hydroxybutanoyl)glucopyranoside] (viscumneoside IX; 1) and homoeriodictyol 7‐O‐β‐D‐[6‐(3‐hydroxybutanoyl)glucopyranosyl](1→2)‐β‐D‐glucopyranoside (viscumneoside X; 2), together with four known flavanoids, 2‐homoeriodictyol 7‐O‐β‐D‐glucopyranoside (3), viscumneoside I (4), viscumneoside III (5), and 4′,5‐dihydroxy‐3′‐methoxy‐7‐(2‐O‐α‐L‐rhamnopyranosyl‐β‐D‐glucopyranosyloxy)flavanone (6) were isolated from stems and leaves of Viscum coloratum. Their structures were elucidated on the basis of their NMR spectra, HR‐FAB‐MS data, and acid hydrolysis. Inhibitory effects of the four compounds 1–4 on the formation of osteoclast‐like multinucleated cells were investigated. As a result, all the four flavanoids showed significant inhibitory effects on the formation of osteoclast‐like multinuclear cells even at a low concentration of 2 μg/ml. The activities of 1–4 at such a concentration exceeded or approximated to that of elcitonin, the positive control drug at a concentration of 2 U/ml, suggesting that they may be of interest for the development of new anti‐osteoporosis drugs.
Pollen Aroma Fingerprint of two Sunflower (Helianthus annuus L.) Genotypes Characterized by Different Pollen Colors
Authors: Bertoli Alessandra , Fambrini Marco , Doveri Silvia , Leonardi Michele , Pugliesi Claudio , Pistelli Luisa 
Published: September 2011

AbstractSamples of fresh pollen grains, collected from capitula in full bloom from two genotypes of sunflower (Helianthus annuus L.) and characterized by a different color, i.e., white‐cream (WC) and orange (O), were analyzed by the HS‐SPME (headspacesolid phase microextraction)/GC/MS technique. This study defined for the first time the fingerprint of the sunflower pollen, separated from the disc flowers, to define its contribution to the inflorescence aroma. In the GC/MS fingerprints of the WC and O genotypes, 61 and 62 volatile compounds were identified, respectively. Monoterpene hydrocarbons (34% in O vs. 28% in WC) and sesquiterpene hydrocarbons (37% in O vs. 31% in WC) were ubiquitous in all samples analyzed and represented the main chemical classes. α‐Pinene (21% in O vs. 20% in WC) and sabinene (11% in O vs. 6% in WC) were the dominant volatiles, but also a full range of aliphatic hydrocarbons and their oxygenated derivatives gave a decisive contribution to the aroma composition (10% in O vs. 12% in WC). In addition, dendrolasin (3% in O vs. 4% in WC) and some minor constituents such as (E)‐hex‐2‐en‐1‐ol (0.4% in O vs. 0.1% in WC) were pointed out not only for their contribution to the pollen scent, but also for their well‐known role in the plant ecological relationships. Having evaluated two pollen morphs with different carotenoid‐based colors, the study sought to highlight also the presence of some volatile precursors or derivatives of these pigments in the aroma. However, the pollen aroma of the two selected genotypes made a specific chemical contribution to the sunflower inflorescence scent without any influence on carotenoid derivatives.
Evaluation of Differences in the Aroma Composition of Free‐Run and Pressed Neutral Grape Juices Obtained from Emir (Vitis vinifera L.)
Authors: Selli Serkan , Bagatar Berfu , Sen Kemal , Kelebek Haşim 
Published: September 2011

AbstractIn this study, the differences in the aroma compounds released after the free‐run and pressed juices of cv. Emir grape (Vitis vinifera L.) were evaluated. Aroma compounds were obtained by liquid‐liquid extraction with CH2Cl2, and then analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). According to the results, pressing uniformly increased the levels of the aromatic constituents, but this treatment lowered the grape juice quality for winemaking by increasing the total phenolic compounds, browning index, and C6‐alcohol levels (green‐herbaceaous odor) as compared to the free‐run juice. From all the aroma compounds identified in both juices, hexan‐1‐ol, (E)‐hex‐2‐en‐1‐ol, isobutanol, isoamyl alcohol, and 2‐phenylethanol were the most abundant volatile compounds.
Climate Friendly Coal from Hydrothermal Carbonization of Biomass
Authors: Buttmann M. 
Published: September 2011

AbstractEs wird das Verfahren der Hydrothermalen Karbonisierung (HTC) von biogenen Reststoffen und die Umsetzung in einer kontinuierlich laufenden, industriellen Anlage beschrieben. Die Vorteile des Verfahrens zur Verwertung der Biomasse und die Energiebilanz werden erläutert. Die Produkteigenschaften werden exemplarisch für HTC‐Kohle aus Klärschlamm aufgezeigt. Es wird dargelegt, dass das Verfahren eine gute Energieeffizienz aufweist und für die energetische Verwertung unterschiedlicher Eingangsstoffe gut geeignet ist.