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Andrew J Pell, Kevin J Sanders, Sebastian Wegner, Guido Pintacuda, Clare P Grey
We propose two broadband pulse schemes for (14)N solid-state magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) that achieves (i) complete population inversion and (ii) efficient excitation of the double-quantum spectrum using low-power single-sideband-selective pulses. We give a comprehensive theoretical description of both schemes using a common framework that is based on the jolting-frame formalism of Caravatti et al. [J. Magn. Reson. 55, 88 (1983)]. This formalism is used to determine for the first time that we can obtain complete population inversion of (14)N under low-power conditions, which we do here using single-sideband-selective adiabatic pulses...
May 21, 2017: Journal of Chemical Physics
Thomas R Vetter
The assessment of a new or existing treatment or intervention typically answers 1 of 3 research-related questions: (1) "Can it work?" (efficacy); (2) "Does it work?" (effectiveness); and (3) "Is it worth it?" (efficiency or cost-effectiveness). There are a number of study designs that on a situational basis are appropriate to apply in conducting research. These study designs are classified as experimental, quasi-experimental, or observational, with observational studies being further divided into descriptive and analytic categories...
June 2017: Anesthesia and Analgesia
A Petra Dral, Caroline Lievens, Johan E Ten Elshof
It is generally assumed that the hydrothermal stability of organically modified silica networks is promoted by high mono-mer connectivity, network flexibility and the presence of hydrophobic groups in the network. In this study a range of organosilica compositions is synthesized to explore the extent to which these factors play a role in the hydrothermal dis-solution of these materials. Compositions were synthesized from hexafunctional organically bridged silsesquioxanes (OR1)3Si-R-Si(OR1)3 (R = -CH2-, -C2H4-, -C6H12-, -C8H16-, -p-C6H4-; R1 = -CH3, -C2H5), tetrafunctional (OEt)2Si(CH3)-C2H4-Si(CH3)(OEt)2 and Si(OEt)4, trifunctional silsesquioxanes R'-Si(OMe)3 (R'=CH3, n-C3H7, cyclo-C6H11, phenyl), and bifunc-tional Si(i-C3H7)2(OMe)2...
May 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Michael S Caplan
No abstract text is available yet for this article.
May 17, 2017: Nature Reviews. Gastroenterology & Hepatology
Dragan V Ilic, Biljana Andjelski Radicevic, Anely Nedelcheva, Ivana Djurovic, Dejan Ostojic
BACKGROUND/AIM: There are still unrevealed treasures of traditional dental medicine, that is, the reason to investigate and present various ways in treatment of oral and orofacial tissues, as well as magic and religious elements involved in representative areas among Serbs. MATERIALS AND METHODS: Information was collected from the elderly non-professional folk dentists and herbalists with the additional help of local physicians and dentists that was done through questionnaire and personal interviews...
April 2017: Journal of Intercultural Ethnopharmacology
Mark Zastrow
No abstract text is available yet for this article.
May 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
Tonje H Haukaas, Leslie R Euceda, Guro F Giskeødegård, Tone F Bathen
Despite progress in early detection and therapeutic strategies, breast cancer remains the second leading cause of cancer-related death among women globally. Due to the heterogeneity and complexity of tumor biology, breast cancer patients with similar diagnosis might have different prognosis and response to treatment. Thus, deeper understanding of individual tumor properties is necessary. Cancer cells must be able to convert nutrients to biomass while maintaining energy production, which requires reprogramming of central metabolic processes in the cells...
May 16, 2017: Metabolites
Sachin R Chaudhari, John M Griffin, Katharina Broch, Anne Lesage, Vincent Lemaur, Dmytro Dudenko, Yoann Olivier, Henning Sirringhaus, Lyndon Emsley, Clare P Grey
Conjugated polymers show promising properties as cheap, sustainable and solution-processable semiconductors. A key challenge in the development of these materials is to determine the polymer chain structure, conformation and packing in both the bulk polymer and in thin films typically used in devices. However, many characterisation techniques are unable to provide atomic-level structural information owing to the presence of disorder. Here, we use molecular modelling, magic-angle spinning (MAS) and dynamic nuclear polarisation surface-enhanced NMR spectroscopy (DNP SENS) to characterise the polymer backbone group conformations and packing arrangement in the high-mobility donor-acceptor copolymer diketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene (DPP-DTT)...
April 1, 2017: Chemical Science
Somnath Karmakar, Anit Sane, S Bhattacharya, Shankar Ghosh
Magic sand, a hydrophobic toy granular material, is widely used in popular science instructions because of its nonintuitive mechanical properties. A detailed study of the failure of an underwater column of magic sand shows that these properties can be traced to a single phenomenon: the system self-generates a cohesive skin that encapsulates the material inside. The skin, consisting of pinned air-water-grain interfaces, shows multiscale mechanical properties: they range from contact-line dynamics in the intragrain roughness scale, to plastic flow at the grain scale, all the way to sample-scale mechanical responses...
April 2017: Physical Review. E
M Ferro, F Castiglione, W Panzeri, R Dispenza, L Santini, H J Karlsson, P P de Wit, A Mele
We report on the direct assessment of the degree of substitution (DS) of carboxymethyl cellulose (CMC) by High Resolution Magic Angle Spinning (HR-MAS) (13)C NMR spectroscopy. The method is applied to industrial CMCs with low and high viscosity and nominal DS, purified and technical samples, and from cellulose linters or wood. The preparation of a set of purified CMC working standards with accurate DS values for the method validation is also described. The DS values determined via HR-MAS (13)C NMR on the industrial samples are critically compared to the corresponding values achieved through the USP 37 〈281〉 method (ASH method) and the HPLC method, and the advantages and limitations of the HR-MAS NMR method highlighted...
August 1, 2017: Carbohydrate Polymers
Chen Song, Jörg Matysik, Franz Mark
We report solid-state NMR investigations of crystal effects in powdered mesobilirubin-IXα, an open-chain tetrapyrrole that is structurally related to bilirubin-IXα but hydrogenated at the 3- and 18-vinyl groups. (13) C and (15) N cross-polarization magic-angle spinning (CP/MAS) NMR experiments were performed on the compound at natural abundance. To facilitate the spectral analysis, density functional calculations were carried out at the B3LYP/6-311G(d,p) level of theory, using an enneameric cluster to simulate the solid...
May 2017: Photochemistry and Photobiology
Monica L Hulbert, Julie A Panepinto, J Paul Scott, Robert I Liem, Lawrence J Cook, Timothy Simmons, David C Brousseau
BACKGROUND: Little is known about red blood cell (RBC) transfusion practices for children hospitalized for a sickle cell vaso-occlusive pain crisis (VOC). We hypothesized that transfusion would be associated with the development of acute chest syndrome (ACS), lower hemoglobin (Hb) concentration, and lack of hydroxyurea therapy. STUDY DESIGN AND METHODS: This is a secondary analysis of all children admitted for a sickle cell pain crisis enrolled in the Magnesium in Crisis (MAGiC) randomized trial; all had HbSS or S-β(0) thalassemia...
May 12, 2017: Transfusion
Liudmila G Korkina, Wolfgang Mayer, Chiara de Luca
Recently, aggressive advertisement claimed a "magic role" for plant stem cells in human skin rejuvenation. This review aims to shed light on the scientific background suggesting feasibility of using plant cells as a basis of anti-age cosmetics. When meristem cell cultures obtained from medicinal plants are exposed to appropriate elicitors/stressors (ultraviolet, ultrasound ultraviolet (UV), ultrasonic waves, microbial/insect metabolites, heavy metals, organic toxins, nutrient deprivation, etc.), a protective/adaptive response initiates the biosynthesis of secondary metabolites...
May 12, 2017: Biomolecules
Yuan Zeng, Zhiqin Peng, Bing Wang, Zhiwen Hu, Junmin Wan, Yang Zhou
The enzymatic degradation of silk by protease XIV has been investigated by using scanning electron microscopy (SEM), Fourier transfer infrared spectroscopy (FTIR), solid-state (13)C nuclear magnetic resonance of cross-polarization/magic angle spinning ((13)C CP/MAS solid state NMR) and electron paramagnetic resonance (EPR). Micro-morphology of protease XIV aged samples showed that microfilaments were stripped out from the surface of silk fibers. The results of FTIR and (13)C CP/MAS solid-state NMR indicated that the enzymatic degradation process could be divided into two stages...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Tetsuo Asakura, Kenta Miyazawa, Yugo Tasei, Shunsuke Kametani, Yasumoto Nakazawa, Akihiro Aoki, Akira Naito
Samia cynthia ricini (S. c. ricini) is one of the wild silkworms. Their silk fibroins have been paid attention as potentially valuable biomedical materials as well as Bombyx mori silk fibroins, but detailed information on the packing arrangement of the fibers is still not currently well understood at a molecular level. In this study, 34 mer model peptides, GGAGGGYGGDGG(A)12GGAGDGYGAG with different (13)C labeled positions have been synthesized as a typical sequence of the primary structure of S. c. ricini silk fibroins made up of tandemly repeated sequences of polyalanine as the crystalline region and glycin-rich sequences as the non-crystalline region...
May 11, 2017: Physical Chemistry Chemical Physics: PCCP
Mukul G Jain, Daniela Lalli, Jan Stanek, Chandrakala Gowda, Satya Prakash, Tom S Schwarzer, Tobias Schubeis, Kathrin Castiglione, Loren B Andreas, P K Madhu, Guido Pintacuda, Vipin Agarwal
Very fast magic-angle spinning (MAS > 80 kHz) NMR combined with high-field magnets has enabled the acquisition of proton-detected spectra in fully protonated solid samples with sufficient resolution and sensitivity. One of the primary challenges in structure determination of protein is observing long-range (1)H-(1)H contacts. Here we use band-selective spin-lock pulses to obtain selective (1)H-(1)H contacts (e.g., H(N)-H(N)) on the order of 5-6 Å in fully protonated proteins at 111 kHz MAS. This approach is a major advancement in structural characterization of proteins given that magnetization can be selectively transferred between protons that are 5-6 Å apart despite the presence of other protons at shorter distance...
May 15, 2017: Journal of Physical Chemistry Letters
Ravikumar Ramakrishnaiah, Abdulaziz Abdullah Al Kheraif, Ashfaq Mohammad, Darshan Devang Divakar, Sunil Babu Kotha, Sree Lalita Celur, Mohamed I Hashem, Pekka K Vallittu, Ihtesham Ur Rehman
The current study was aimed to fabricate customized root form dental implant using additive manufacturing technique for the replacement of missing teeth. The root form dental implant was designed using Geomagic™ and Magics™, the designed implant was directly manufactured by layering technique using ARCAM A2™ electron beam melting system by employing medical grade Ti-6Al-4V alloy powder. Furthermore, the fabricated implant was characterized in terms of certain clinically important parameters such as surface microstructure, surface topography, chemical purity and internal porosity...
May 2017: Saudi Journal of Biological Sciences
Katarina Stojkovic, Valéria Szijártó, Marta Kaszowska, Tomasz Niedziela, Katharina Hartl, Gábor Nagy, Jolanta Lukasiewicz
Klebsiella pneumoniae is a Gram-negative, ubiquitous bacterium capable of causing severe nosocomial infections in individuals with impaired immune system. Emerging multi-drug resistant strains of this species and particularly carbapenem-resistant strains pose an urgent threat to public health. The lipopolysaccharide (LPS) O-antigen is the main surface antigen. It contributes to the virulence of this species and determines the O-serotype of K. pneumoniae isolates. Among the nine main O-serotypes of K. pneumoniae, O1-and O2-type pathogens are causative agents of over 50% of all infections...
2017: Frontiers in Microbiology
P Van de Voorde, S Gautama, A Momont, C M Ionescu, P De Paepe, N Fraeyman
Defibrillation within the first minutes after sudden cardiac arrest can save many quality-adjusted life years. Yet, despite enormous investments, 'healthcare' is still unable to provide this for the majority of patients. Emergency Medical Services often have a too long mean response time and many issues surround Public Access Defibrillation programs. In this article we argument that AED-equipped drones could be the 'magic bullet'. They are easily deployed and fast, and have a relatively low operational cost...
May 6, 2017: Resuscitation
Beatriz Santiago-González, Angelo Monguzzi, Valerio Pinchetti, Alberto Casu, Mirko Prato, Roberto Lorenzi, Marcello Campione, Norberto Chiodini, Carlo Santambrogio, Francesco Meinardi, Liberato Manna, Sergio Brovelli
The insertion of intentional impurities, commonly referred to as doping, into colloidal semiconductor quantum dots (QDs) is a powerful paradigm for tailoring their electronic, optical and magnetic behaviours beyond what is obtained with size-control and heterostructuring motifs. Advancements in colloidal chemistry have led to nearly atomic precision of the doping level in both lightly and heavily doped QDs. The doping strategies currently available, however, operate at the ensemble level, resulting in a Poisson distribution of impurities across the QD population...
May 9, 2017: ACS Nano
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