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https://www.readbyqxmd.com/read/28335582/nonradiative-relaxation-mechanisms-of-uv-excited-phenylalanine-residues-a-comparative-computational-study
#1
Momir Mališ, Nađa Došlić
The present work is directed toward understanding the mechanisms of excited state deactivation in three neutral model peptides containing the phenylalanine residue. The excited state dynamics of theγL(g+)folded form of N-acetylphenylalaninylamide (NAPA B) and its amide-N-methylated derivative (NAPMA B) is reviewed and compared to the dynamics of the monohydrated structure of NAPA (NAPAH). The goal is to unravel how the environment, and in particular solvation, impacts the photodynamics of peptides. The systems are investigated using reaction path calculations and surface hopping nonadiabatic dynamics based on the coupled cluster doubles (CC2) method and time-dependent density functional theory...
March 21, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28335297/rotation-of-magnetization-derived-from-brownian-relaxation-in-magnetic-fluids-of-different-viscosity-evaluated-by-dynamic-hysteresis-measurements-over-a-wide-frequency-range
#2
Satoshi Ota, Ryoichi Kitaguchi, Ryoji Takeda, Tsutomu Yamada, Yasushi Takemura
The dependence of magnetic relaxation on particle parameters, such as the size and anisotropy, has been conventionally discussed. In addition, the influences of external conditions, such as the intensity and frequency of the applied field, the surrounding viscosity, and the temperature on the magnetic relaxation have been researched. According to one of the basic theories regarding magnetic relaxation, the faster type of relaxation dominates the process. However, in this study, we reveal that Brownian and Néel relaxations coexist and that Brownian relaxation can occur after Néel relaxation despite having a longer relaxation time...
September 10, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335240/gd-si-oxide-nanoparticles-as-contrast-agents-in-magnetic-resonance-imaging
#3
Alejandro Cabrera-García, Alejandro Vidal-Moya, Ángela Bernabeu, Jesús Pacheco-Torres, Elisa Checa-Chavarria, Eduardo Fernández, Pablo Botella
We describe the synthesis, characterization and application as contrast agents in magnetic resonance imaging of a novel type of magnetic nanoparticle based on Gd-Si oxide, which presents high Gd(3+) atom density. For this purpose, we have used a Prussian Blue analogue as the sacrificial template by reacting with soluble silicate, obtaining particles with nanorod morphology and of small size (75 nm). These nanoparticles present good biocompatibility and higher longitudinal and transversal relaxivity values than commercial Gd(3+) solutions, which significantly improves the sensitivity of in vivo magnetic resonance images...
June 8, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335228/fabricating-water-dispersible-superparamagnetic-iron-oxide-nanoparticles-for-biomedical-applications-through-ligand-exchange-and-direct-conjugation
#4
Tina Lam, Pramod K Avti, Philippe Pouliot, Foued Maafi, Jean-Claude Tardif, Éric Rhéaume, Frédéric Lesage, Ashok Kakkar
Stable superparamagnetic iron oxide nanoparticles (SPIONs), which can be easily dispersed in an aqueous medium and exhibit high magnetic relaxivities, are ideal candidates for biomedical applications including contrast agents for magnetic resonance imaging. We describe a versatile methodology to render water dispersibility to SPIONs using tetraethylene glycol (TEG)-based phosphonate ligands, which are easily introduced onto SPIONs by either a ligand exchange process of surface-anchored oleic-acid (OA) molecules or via direct conjugation...
May 26, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335193/facile-synthesis-of-gd-functionalized-gold-nanoclusters-as-potential-mri-ct-contrast-agents
#5
Wenjun Le, Shaobin Cui, Xin Chen, Huanhuan Zhu, Bingdi Chen, Zheng Cui
Multi-modal imaging plays a key role in the earlier detection of disease. In this work, a facile bioinspired method was developed to synthesize Gd-functionalized gold nanoclusters (Gd-Au NCs). The Gd-Au NCs exhibit a uniform size, with an average size of 5.6 nm in dynamic light scattering (DLS), which is a bit bigger than gold clusters (3.74 nm, DLS), while the fluorescent properties of Gd-Au NCs are almost the same as that of Au NCs. Moreover, the Gd-Au NCs exhibit a high longitudinal relaxivity value (r1) of 22...
April 9, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335103/correlation-between-gastric-emptying-and-gastric-adaptive-relaxation-influenced-by-amino-acids
#6
Masayuki Uchida, Orie Kobayashi, Chizuru Saito
Background/Aims: Amino acids have many physiological activities. We report the correlation between gastric emptying and gastric adaptive relaxation using tryptophan and amino acids with a straight alkyl chain, hydroxylated chain, and branched chain. Here we sought to further clarify the correlation between gastric emptying and gastric adaptive relaxation by using other amino acids. Methods: In Sprague-Dawley rats, gastric emptying was evaluated by a breath test using [1-¹³C] acetic acid...
March 23, 2017: Journal of Neurogastroenterology and Motility
https://www.readbyqxmd.com/read/28335026/melting-temperature-highlights-functionally-important-rna-structure-and-sequence-elements-in-yeast-mrna-coding-regions
#7
Fei Qi, Dmitrij Frishman
Secondary structure elements in the coding regions of mRNAs play an important role in gene expression and regulation, but distinguishing functional from non-functional structures remains challenging. Here we investigate the dependence of sequence-structure relationships in the coding regions on temperature based on the recent PARTE data by Wan et al. Our main finding is that the regions with high and low thermostability (high Tm and low Tm regions) are under evolutionary pressure to preserve RNA secondary structure and primary sequence, respectively...
March 7, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334715/potassium-channel-independent-relaxing-influence-of-adipose-tissue-on-mouse-carotid-artery
#8
Marta Laskowski, Cathrin Andersson, Emilie Eliasson, Veronika Golubinskaya, Holger Nilsson
Since the cardiovascular consequences of obesity reportedly vary in different types of obesity, we investigated the influence of adipose tissue from different locales on the phenylephrine-induced tone of the mouse carotid artery. Vessels were mounted in a Mulvany-Halpern-type wire myograph, and adipose tissue, from the back (brown) or mesenteric or inguinal subcutaneous (white), was placed around the artery. Contractile responses to phenylephrine were not affected by brown adipose tissue but were reduced (p < 0...
March 24, 2017: Journal of Vascular Research
https://www.readbyqxmd.com/read/28333985/the-role-of-above-ground-competition-and-nitrogen-vs-phosphorus-enrichment-in-seedling-survival-of-common-european-plant-species-of-semi-natural-grasslands
#9
Tobias Ceulemans, Eva Hulsmans, Sigi Berwaers, Kasper Van Acker, Olivier Honnay
Anthropogenic activities have severely altered fluxes of nitrogen and phosphorus in ecosystems worldwide. In grasslands, subsequent negative effects are commonly attributed to competitive exclusion of plant species following increased above-ground biomass production. However, some studies have shown that this does not fully account for nutrient enrichment effects, questioning whether lowering competition by reducing grassland productivity through mowing or herbivory can mitigate the environmental impact of nutrient pollution...
2017: PloS One
https://www.readbyqxmd.com/read/28333819/practice-bulletin-no-177-obstetric-analgesia-and-anesthesia
#10
(no author information available yet)
Labor causes severe pain for many women. There is no other circumstance in which it is considered acceptable for an individual to experience untreated severe pain that is amenable to safe intervention while the individual is under a physician's care. Many women desire pain management during labor and delivery, and there are many medical indications for analgesia and anesthesia during labor and delivery. In the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labor...
April 2017: Obstetrics and Gynecology
https://www.readbyqxmd.com/read/28333811/practice-bulletin-no-177-summary-obstetric-analgesia-and-anesthesia
#11
(no author information available yet)
Labor causes severe pain for many women. There is no other circumstance in which it is considered acceptable for an individual to experience untreated severe pain that is amenable to safe intervention while the individual is under a physician's care. Many women desire pain management during labor and delivery, and there are many medical indications for analgesia and anesthesia during labor and delivery. In the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labor...
April 2017: Obstetrics and Gynecology
https://www.readbyqxmd.com/read/28333626/temperature-dependence-of-domain-contributions-as-a-function-of-ageing-in-soft-and-hard-lead-zirconate-titanate-piezoelectric-ceramics
#12
Sayyed A Qaisar, Timothy P Comyn, Andrew J Bell
The stress and temperature dependence of three different PZT ceramics have been measured at 48 hours and 1 month after poling. The data were fitted to a modified Rayleigh law in which a negative quadratic stress term accounts for a saturation of the domain wall contributions at higher stress. The relative changes to the fitting parameters can be explained by the materials possessing differences in the concentration of orientable defect dipoles, but with similar distributions of relaxation time constants.
March 22, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28333465/disordering-effects-of-digitonin-on-phospholipid-monolayers
#13
Marta Orczyk, Kamil Wojciechowski, Gerald Brezesinski
Digitonin, a steroidal saponin obtained from the Foxglove plant (Digitalis purpurea), displays a wide spectrum of biological properties and is often used as a model in mechanistic investigations of biological activity of saponins. In the present study, Langmuir monolayers of zwitterionic (DPPC, DMPE, POPC, POPE, DSPC, DSPE, DPPE) and ionic (DPPS, DPPG) phospholipids were employed, in order to better understand the effect of digitonin on the lipid organization. For this purpose, a combination of surface pressure relaxation, infrared reflection absorption spectroscopy (IRRAS) and fluorescence microscopy measurements, was used...
March 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28333456/calixsmaragdyrin-a-versatile-ligand-for-coordination-complexes
#14
Tamal Chatterjee, Brian Molnar, G G Theophall, Way-Zen Lee, K V Lakshmi, Mangalampalli Ravikanth
The Ru(II) and BF2 complexes of calixsmaragdyrin were prepared under simple reaction conditions and characterized by HR-MS, 1D and 2D NMR spectroscopy, optical spectroscopy, and electrochemistry, and the structure of the Ru(II) complex of calixsmaragdyrin was elucidated by X-ray crystallography. The crystal structure of the Ru(II) complex revealed that the Ru(II) ion is hexacoordinate with the three pyrrole nitrogen ligands from the tripyrrin unit of the calixsmaragdyrin macrocycle, and the remaining coordination sites of Ru(II) ion were occupied by two carbonyl groups and one hydroxyl (-OH) group...
March 23, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28333336/comparative-sperm-proteomics-in-mouse-species-with-divergent-mating-systems
#15
Alberto Vicens, Kirill Borziak, Timothy L Karr, Eduardo R S Roldan, Steve Dorus
Sexual selection is the pervasive force underlying the dramatic divergence of sperm form and function. Although it has been demonstrated that testis gene expression evolves rapidly, exploration of the proteomic basis of sperm diversity is in its infancy. We have employed a whole-cell proteomics approach to characterize sperm divergence among closely related Mus species that experience different sperm competition regimes and exhibit pronounced variation in sperm energetics, motility and fertilization capacity...
February 25, 2017: Molecular Biology and Evolution
https://www.readbyqxmd.com/read/28332826/packaged-and-free-stmv-rna-genomes-adopt-distinct-conformational-states
#16
Bridget C Larman, Elizabeth A Dethoff, Kevin M Weeks
The RNA genomes of viruses likely undergo multiple functionally important conformational changes during their replication cycles, changes that are poorly understood at present. We used two complementary in-solution RNA structure probing strategies (SHAPE-MaP and RING-MaP) to examine the structure of the RNA genome of satellite tobacco mosaic virus inside authentic virions and in a capsid-free state. Both RNA states feature similar three-domain architectures in which each major replicative function - translation, capsid coding, and genome synthesis - fall into distinct domains...
March 23, 2017: Biochemistry
https://www.readbyqxmd.com/read/28332691/relaxations-and-phase-transitions-during-the-collapse-of-a-dense-pnipam-microgel-suspension-thorough-insight-using-dielectric-spectroscopy
#17
Man Yang, Chunyan Liu, Yiwei Lian, Kongshuang Zhao, Dan Zhu, Jianfeng Zhou
The dielectric behavior of a thermo-sensitive poly-(N-isopropylacrylamide) (PNIPAM) microgel suspension with a dense concentration was investigated over the frequency range of 40 Hz to 110 MHz in a wide temperature window of 10-60 °C. By successfully removing the electrode polarization effect from the original data, two remarkable and temperature-dependent relaxation processes were observed. Both of the two-phase transition processes, i.e., the colloidal crystal-to-liquid transition, which has not yet been detected by dielectric spectroscopy before, as well as the volume phase transition, were detected by the relaxation parameters...
March 23, 2017: Soft Matter
https://www.readbyqxmd.com/read/28332401/ultrafast-excited-state-dynamics-of-cytosine-aza-derivative-and-analogues
#18
Zhongneng Zhou, Xueyao Zhou, Xueli Wang, Bin Jiang, Yongle Li, Jinquan Chen, Jianhua Xu
Excited state dynamics of 5-azacytosine (5-AC), 2,4-diamino-1,3,5-triazine (2,4-DT), and 2-amino-1,3,5-triazine (2-AT) were comprehensively investigated with steady state absorption, fluorescence and femtosecond transient absorption measurements. Time-dependent density functional theory (TDDFT) calculations were performed to help assign the absorption bands and understand the excited state decay mechanisms. The experimental results of excited singlet state dynamics for 5-AC, 2,4-DT and 2-AT with femtosecond time resolution were reported for the first time...
March 23, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28332039/combined-quantification-of-fatty-infiltration-t-1-relaxation-times-and-t-2-relaxation-times-in-normal-appearing-skeletal-muscle-of-controls-and-dystrophic-patients
#19
Benjamin Leporq, Arnaud Le Troter, Yann Le Fur, Emmanuelle Salort-Campana, Maxime Guye, Olivier Beuf, Shahram Attarian, David Bendahan
OBJECTIVES: To evaluate the combination of a fat-water separation method with an automated segmentation algorithm to quantify the intermuscular fatty-infiltrated fraction, the relaxation times, and the microscopic fatty infiltration in the normal-appearing muscle. MATERIALS AND METHODS: MR acquisitions were performed at 1.5T in seven patients with facio-scapulo-humeral dystrophy and eight controls. Disease severity was assessed using commonly used scales for the upper and lower limbs...
March 22, 2017: Magma
https://www.readbyqxmd.com/read/28331847/learning-parsimonious-classification-rules-from-gene-expression-data-using-bayesian-networks-with-local-structure
#20
Jonathan Lyle Lustgarten, Jeya Balaji Balasubramanian, Shyam Visweswaran, Vanathi Gopalakrishnan
The comprehensibility of good predictive models learned from high-dimensional gene expression data is attractive because it can lead to biomarker discovery. Several good classifiers provide comparable predictive performance but differ in their abilities to summarize the observed data. We extend a Bayesian Rule Learning (BRL-GSS) algorithm, previously shown to be a significantly better predictor than other classical approaches in this domain. It searches a space of Bayesian networks using a decision tree representation of its parameters with global constraints, and infers a set of IF-THEN rules...
March 2017: Data (Basel)
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