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proton density

Mehrnoosh Khodam Hazrati, Zahra Javanshir, Zargham Bagheri
It has been previously indicated that BN nanostructures may be nontoxic and biocompatible. Here the potential application of a B24N24 is explored as a drug delivery system for anti-cancer 5-fluorouracil based on the density functional theory. This drug prefers to attach via its oxygen atoms to the B atoms of the cluster with adsorption energy about -11.90kcalmol(-1) based on the dispersion corrected B3LYP level of theory. To make the cluster more appropriate for drug delivery, we replaced a B atom by Si or Al atom to improve the interaction strength...
August 9, 2017: Journal of Molecular Graphics & Modelling
Thomas Bayer, Werner Adler, Rolf Janka, Michael Uder, Frank Roemer
OBJECTIVE: To study the feasibility of magnetic resonance cinematography of the fingers (MRCF) with comparison of image quality of different protocols for depicting the finger anatomy during motion. MATERIALS AND METHODS: MRCF was performed during a full flexion and extension movement in 14 healthy volunteers using a finger-gating device. Three real-time sequences (frame rates 17-59 images/min) and one proton density (PD) sequence (3 images/min) were acquired during incremental and continuous motion...
August 19, 2017: Skeletal Radiology
Chenxi Hu, Albert J Sinusas, Steffen Huber, Stephanie Thorn, Mitchel R Stacy, Hamid Mojibian, Dana C Peters
BACKGROUND: High resolution 3D T1 mapping is important for assessment of diffuse myocardial fibrosis in left atrium or other thin-walled structures. In this work, we investigated a fast single-TI 3D high resolution T1 mapping method that directly transforms a 3D late gadolinium enhancement (LGE) volume to a 3D T1 map. METHODS: The proposed method, T1-refBlochi, is based on Bloch equation modeling of the LGE signal, a single-point calibration, and assumptions that proton density and T2* are relatively uniform in the heart...
August 18, 2017: Journal of Cardiovascular Magnetic Resonance
Binbin Zhou, Shaofei Li, Xianghu Tang, Pan Li, Xiaomin Cao, Borong Yu, Liangbao Yang, Jinhuai Liu
Intramolecular proton transfer of hypoxanthine, induced by application of a laser on the surface of a bare noble nanomaterial, was monitored in real time using surface-enhanced Raman spectroscopy (SERS). This monitoring demonstrated the dependence of the reaction on the identity of the nanomaterial and on the laser power density. The results pave the way for monitoring the proton transfer reaction in various relevant fields. In addition, we observed the presence of the proton transfer phenomenon of hypoxanthine in serum, providing a way to avoid the effect of proton transfer and hence achieve more reliable spectra of sera for clinical diagnosis...
August 18, 2017: Nanoscale
Nathalie Camus, Nathalie Le Bris, Selbi Nuryyeva, Matthieu Chessé, David Esteban-Gómez, Carlos Platas-Iglesias, Raphaël Tripier, Mourad Elhabiri
The acid-base and copper(ii) coordination properties of three previously described cyclam derivatives are reported. Potentiometry, mass spectrometry, UV-vis absorption spectroscopy, electrochemistry and theoretical calculations were combined to investigate the protonation and binding properties of Bn-cyclam-EtOH (L1), oxo-cyclam-EtOH (L2) and oxo-Bn-cyclam-EtOH (L3). These three cyclams are C-functionalized by a hydroxyethyl pendant arm and display either one N-benzyl group and/or an amide replacing one macrocyclic secondary amine...
August 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Hyeyoung Lee, Dae Won Jun, Bo-Kyeong Kang, Eunwoo Nam, Misoo Chang, Mimi Kim, Soonyoung Song, Byung Chul Yoon, Hang Lak Lee, Oh Young Lee, Ho Soon Choi, Kang Nyeong Lee
The recently developed magnetic resonance imaging (MRI) proton density fat fraction (PDFF) allows measurement of the fat in all segments of hepatic tissue. However, it is time consuming and inconvenient to measure each segment repeatedly. Moreover, volume of each segment also should be adjusted with arithmetic mean of the selected segments when total amount of liver fat is estimated. Therefore, we try to develop a clinically-relevant and applicable method of estimating hepatic fat in PDFF image.A total of 164 adults were enrolled...
August 2017: Medicine (Baltimore)
Richard N Collins, Kevin M Rosso
Molecular-level pathways in the aqueous redox transformation of uranium by iron remain unclear, despite the importance of this knowledge for predicting uranium transport and distribution in natural and engineered environments. As the relative importance of homogeneous versus heterogeneous pathways is difficult to probe experimentally, here we apply computational molecular simulation to isolate rates of key one electron transfer reactions in the homogenous pathway. By comparison to experimental observations the role of the heterogeneous pathway also becomes clear...
August 15, 2017: Journal of Physical Chemistry. A
Sara Moa, Fahmi Himo
Secondary alcohol dehydrogenase from Thermoanaerobacter brockii (TbSADH) is a Zn- and NADP-dependent enzyme that catalyses the reversible transformation of secondary alcohols into ketones. It is of potential biocatalytic interest as it can be used in the synthesis of chiral alcohols by asymmetric reduction of ketones. In this paper, density functional theory calculations are employed to elucidate the origins of the enantioselectivity of TbSADH using a large model of the active site and considering two different substrates, 2-butanol and 3-hexanol...
July 24, 2017: Journal of Inorganic Biochemistry
S Soellner, A Goldmann, D Muelheims, G H Welsch, M Pachowsky
OBJECTIVE: The aim of this study was to compare T2 relaxation times of knee cartilage with intraoperative results for the assessment of early osteoarthritis (OA) and to define T2 values for the differentiation between healthy and degenerated cartilage. DESIGN: Twenty-one patients with cartilage lesions or moderate OA were examined using 3T magnetic resonance imaging (MRI). In this prospective study, a total of 882 regions of interest (ROIs) were examined by a sagittal, multi-echo, spin-echo T2 sequence and a morphological high-resolution three-dimensional, fat-saturated proton-density space sequence...
August 8, 2017: Osteoarthritis and Cartilage
Margareta R A Blomberg, Pia Ädelroth
Bacterial NO-reductases (NOR) belong to the heme-copper oxidase (HCuO) superfamily, in which most members are O2-reducing, proton-pumping enzymes. This study is one in a series aiming to elucidate the reaction mechanisms of the HCuOs, including the mechanisms for cellular energy conservation. One approach towards this goal is to compare the mechanisms for the different types of HCuOs, cytochrome c oxidase (CcO) and NOR, reducing the two substrates O2 and NO. Specifically in this study, we describe the mechanism for oxygen reduction in cytochrome c dependent NOR (cNOR)...
August 8, 2017: Biochimica et Biophysica Acta
Xia Sheng, Hailiang Zhao, Lin Du
Theoretical calculations at the B3LYP-D3/aug-cc-pVTZ (aug-cc-pV(T+d)Z for sulfur) level were used to investigate the contribution of methyl hydrogen sulfate (MHS) to new particle formation with the common atmospheric aerosol nucleation precursors including water (H2O), ammonia (NH3), and dimethylamine (DMA). A typical characteristic feature of the MHS-containing complexes is the formation of six- or eight-membered ring structures via SOH⋯O (MHS donor), OH⋯O/N (H2O donor) and NH⋯O/N (NH3/DMA donor). The stability of the complexes was evaluated based on the calculated binding energies...
August 4, 2017: Chemosphere
Michele Di Martino, Kameliya Koryukova, Mario Bezzi, Carlo Catalano
Non-invasive diagnosis and quantification of liver steatosis is important to overcome limits of liver biopsy, in order to follow up patients during their therapy and to establish a reference standard that can be used in clinical trials and longitudinal studies. Imaging offers several methods in this setting: ultrasound, which is the cheapest technique and easy to perform; magnetic resonance spectroscopy (MRS), which reflects the real content of triglycerides in a specific volume; and proton density fat fraction (PDFF) magnetic resonance, which is a simple method that reflects the distribution of the fat in the whole liver...
August 11, 2017: Children
N T Henthorn, J W Warmenhoven, M Sotiropoulos, R I Mackay, K J Kirkby, M J Merchant
Monte Carlo based simulation has proven useful in investigating the effect of proton-induced DNA damage and the processes through which this damage occurs. Clustering of ionizations within a small volume can be related to DNA damage through the principles of nanodosimetry. For simulation, it is standard to construct a small volume of water and determine spatial clusters. More recently, realistic DNA geometries have been used, tracking energy depositions within DNA backbone volumes. Traditionally a chromatin fiber is built within the simulation and identically replicated throughout a cell nucleus, representing the cell in interphase...
August 9, 2017: Radiation Research
Kun Li, Jun Du, Li-Xin Huang, Li Ni, Tao Liu, Hui-Lin Yang
We performed this meta-analysis to examine the diagnostic accuracy of MRI for the diagnosis of anterior cruciate ligament (ACL) injury in comparison to arthroscopy. We also compared the diagnostic accuracy of MRI with magnetic field intensities (MFI) greater than or equal to 1.5T with those below 1.5T, in addition to different MRI sequences. Studies relevant to the diagnosis of ACL injury by MRI and arthroscopy were analyzed. Computer and manual retrieval were carried out on studies published between January 1, 2006 and May 31, 2016...
August 8, 2017: Scientific Reports
Yan-Zhen Zheng, Geng Deng, Qin Liang, Da-Fu Chen, Rui Guo, Rong-Cai Lai
Among the multiple components of propolis, flavonoids contribute greatly to the antioxidant activities of propolis. Flavonoids mainly exist in the form of sugar-conjugated derivatives. Quercetin glycosides represent the predominant flavonoid fraction in propolis. In this work, density functional theory (DFT) calculations were applied to analyze the antioxidative properties of quercetin and its glucosides in the gas and in the liquid phase (ethanol, water). Three main antioxidant mechanisms, hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) were used to analyze the antioxidative capacity of the investigated compounds...
August 8, 2017: Scientific Reports
Meng Duan, Lei Zhu, Xiaotian Qi, Zhaoyuan Yu, Yingzi Li, Ruopeng Bai, Yu Lan
Density functional M11 was used to study the mechanism and enantioselectivity of a binaphthophosphepine-catalyzed intramolecular [3 + 2] cycloaddition reaction. The computational results revealed that this reaction proceeds through nucleophilic addition of the phosphine catalyst to the allene, which yields a zwitterionic phosphonium intermediate. The subsequent stepwise [3 + 2] annulation process, which starts with the intramolecular nucleophilic addition of the allenoate moiety to the electron-deficient olefin group, determines the enantioselectivity of the reaction...
August 8, 2017: Scientific Reports
Rajendran Niranjana Devi, Maria G Khrenova, Samuel Israel, Chellam Anzline, Andrey A Astakhov, Vladimir G Tsirelson
A combined molecular docking, QM, and QM/MM dynamics modeling complemented with electron-density based descriptors computed at the B3LYP/6-311G++(d,p) level of theory have been carried out in order to understand the ability of the drugs rhodanine (RD) and 2,4-thiazolidinedione (TZD) in the effective treatment of type 2 diabetes mellitus. The global HOMO/LUMO descriptors provided just a very rough estimate of the chemical reactivity of both molecules, while the features of electron density studied in terms of its Laplacian and electrostatic potential allowed identifying the local electron rich/poor sites which were associated with the regions of electrophilic/nucleophilic attacks in RD and TZD...
September 2017: Journal of Molecular Modeling
Yuxiang Mo, Guocai Tian, Jianmin Tao
Recently, Tao and Mo proposed a meta-generalized gradient approximation for the exchange-correlation energy with remarkable accuracy for molecules, solids, and surfaces. To better understand this functional, in this work, we make a comparative study of the TM and TMTPSS functionals, the latter of which is a combination of the TM exchange with the original TPSS correlation functional, on atoms, molecules, and hydrogen-bonded complexes by the use of eight well-known databases. Our calculations show that, while the TMTPSS functional achieves better accuracy for atomization energies or enthalpies of formation, harmonic vibrational frequencies, and atomic excitation energies than the TM functional, it is less accurate for proton affinities, molecular bond lengths, and in particular hydrogen-bonded complexes...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Lars Kasper, Maria Engel, Christoph Barmet, Maximilian Haeberlin, Bertram J Wilm, Benjamin E Dietrich, Thomas Schmid, Simon Gross, David O Brunner, Klaas E Stephan, Klaas P Pruessmann
We report the deployment of spiral acquisition for high-resolution structural imaging at 7T. Long spiral readouts are rendered manageable by an expanded signal model including static off-resonance and B0 dynamics along with k-space trajectories and coil sensitivity maps. Image reconstruction is accomplished by inversion of the signal model using an extension of the iterative non-Cartesian SENSE algorithm. Spiral readouts up to 25 ms are shown to permit whole-brain 2D imaging at 0.5 mm in-plane resolution in less than a minute...
July 31, 2017: NeuroImage
Xialiang Li, Haitao Lei, Xiaojun Guo, Xueli Zhao, Shuping Ding, Xueqing Gao, Wei Zhang, Rui Cao
A cobalt complex of 5,15-bis-(pentafluorophenyl)-10-(4)-(1-pyrenyl)phenyl corrole containing a triphenylphosphine axial ligand (1-PPh3) was synthesized and examined as an electrocatalyst for the hydrogen evolution reaction (HER). When supported on graphene (G), the resulted 1-PPh3/G material can catalyze HER in aqueous solutions over a wide pH range of 0-14 with high efficiency and durability. The significantly enhanced activity of 1-PPh3/G, compared with those of its analogues 1-py/G (the Co-bound axial ligand is pyridine instead of triphenylphosphine) and 2-py/G (Co complex of 5,10,15-tris(pentafluorophenyl)corrole), highlights the effects of pyrenyl substituent and triphenylphosphine axial ligand on HER...
August 3, 2017: ChemSusChem
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