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https://www.readbyqxmd.com/read/29166039/segmental-dynamics-of-polyethylene-alt-propylene-studied-by-nmr-spin-echo-techniques
#1
A Lozovoi, C Mattea, M Hofmann, K Saalwaechter, N Fatkullin, S Stapf
Segmental dynamics of a highly entangled melt of linear polyethylene-alt-propylene with a molecular weight of 200 kDa was studied with a novel proton nuclear magnetic resonance (NMR) approach based upon (1)H → (2)H isotope dilution as applied to a solid-echo build-up function I(SE)(t), which is constructed from the NMR spin echo signals arising from the Hahn echo (HE) and two variations of the solid-echo pulse sequence. The isotope dilution enables the separation of inter- and intramolecular contributions to this function and allows one to extract the segmental mean-squared displacements in the millisecond time range, which is hardly accessible by other experimental methods...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166037/adenosine-triphosphate-diffusion-through-poly-ethylene-glycol-diacrylate-hydrogels-can-be-tuned-by-cross-link-density-as-measured-by-pfg-nmr
#2
Günter Majer, Alexander Southan
The diffusion of small molecules through hydrogels is of great importance for many applications. Especially in biological contexts, the diffusion of nutrients through hydrogel networks defines whether cells can survive inside the hydrogel or not. In this contribution, hydrogels based on poly(ethylene glycol) diacrylate with mesh sizes ranging from ξ = 1.1 to 12.9 nm are prepared using polymers with number-average molecular weights between Mn = 700 and 8000 g/mol. Precise measurements of diffusion coefficients D of adenosine triphosphate (ATP), an important energy carrier in biological systems, in these hydrogels are performed by pulsed field gradient nuclear magnetic resonance...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166013/slow-magnetic-relaxation-in-a-dysprosium-ammonia-metallocene-complex
#3
Selvan Demir, Monica D Boshart, Jordan F Corbey, David H Woen, Miguel I Gonzalez, Joseph W Ziller, Katie R Meihaus, Jeffrey R Long, William J Evans
We report the serendipitous discovery and magnetic characterization of a dysprosium bis(ammonia) metallocene complex, [(C5Me5)2Dy(NH3)2](BPh4) (1), isolated in the course of performing a well-established synthesis of the unsolvated cationic complex [(C5Me5)2Dy][(μ-Ph)2BPh2]. While side reactivity studies suggest that this bis(ammonia) species owes its initial incidence to impurities in the DyCl3(H2O)x starting material, we were able to independently prepare 1 and its tetrahydrofuran (THF) derivative, [(C5Me5)2Dy(NH3)(THF)](BPh4) (2), from the reaction of [(C5Me5)2Dy][(μ-Ph)2BPh2] with ammonia in THF...
November 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29166009/formation-of-spherical-aromatic-endohedral-metallic-fullerenes-evaluation-of-magnetic-properties-of-m-c28-m-ti-zr-and-hf-from-dft-calculations
#4
Alvaro Muñoz-Castro, R Bruce King
The small C28 cage has been shown experimentally to encapsulate titanium, zirconium, and hafnium (M), among other elements. Here, we explore computationally its magnetic response properties accounting for both global and local shielding tensors. Our results exhibit a continuous shielding region for M@C28 for an orientation-averaged applied field thereby differing from that observed for the hollow C28 structure. Moreover, under a specific orientation of the applied field a long-ranged shielding cone is obtained supporting the spherical aromatic behavior expected by the 2(N + 1)(2) Hirsch rule for M@C28, standing for its particular abundance...
November 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29165995/magnetic-particle-imaging-for-highly-sensitive-quantitative-and-safe-in-vivo-gut-bleed-detection-in-a-murine-model
#5
Elaine Y Yu, Prashant Chandrasekharan, Ran Berzon, Zhi Wei Tay, Xinyi Y Zhou, Amit P Khandhar, R Matthew Ferguson, Scott J Kemp, Bo Zheng, Patrick W Goodwill, Michael F Wendland, Kannan M Krishnan, Spencer Behr, Jonathan Carter, Steven M Conolly
Gastrointestinal (GI) bleeding causes more than 300,000 hospitalizations per year in the United States. Imaging plays a crucial role in accurately locating the source of the bleed for timely intervention. Magnetic Particle Imaging (MPI) is an emerging clinically translatable imaging modality that images superparamagnetic iron-oxide (SPIO) tracers with extraordinary contrast and sensitivity. This linearly quantitative modality has zero background tissue signal and zero signal depth attenuation. MPI is also safe: there is zero ionizing radiation exposure to the patient and clinically approved tracers can be used with MPI...
November 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/29165872/manganese-dioxide-coated-ws2-fe3-o4-ssio2-nanocomposites-for-ph-responsive-mr-imaging-and-oxygen-elevated-synergetic-therapy
#6
Guangbao Yang, Rui Zhang, Chao Liang, He Zhao, Xuan Yi, Sida Shen, Kai Yang, Liang Cheng, Zhuang Liu
Recently, the development of multifunctional theranostic nanoplatforms to realize tumor-specific imaging and enhanced cancer therapy via responding or modulating the tumor microenvironment (TME) has attracted tremendous interests in the field of nanomedicine. Herein, tungsten disulfide (WS2 ) nanoflakes with their surface adsorbed with iron oxide nanoparticles (IONPs) via self-assembly are coated with silica and then subsequently with manganese dioxide (MnO2 ), on to which polyethylene glycol (PEG) is attached...
November 22, 2017: Small
https://www.readbyqxmd.com/read/29165647/levels-of-extremely-low-frequency-electric-and-magnetic-fields-from-overhead-power-lines-in-the-outdoor-environment-of-ramallah-city-palestine
#7
Falastine Abuasbi, Adnan Lahham, Issam Rashid Abdel-Raziq
In this study, levels of extremely low-frequency electric and magnetic fields originated from overhead power lines were investigated in the outdoor environment in Ramallah city, Palestine. Spot measurements were applied to record fields intensities over 6-min period. The Spectrum Analyzer NF-5035 was used to perform measurements at 1 m above ground level and directly underneath 40 randomly selected power lines distributed fairly within the city. Levels of electric fields varied depending on the line's category (power line, transformer or distributor), a minimum mean electric field of 3...
November 18, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29165377/a-novel-3d-pedestrian-navigation-method-for-a-multiple-sensors-based-foot-mounted-inertial-system
#8
Wei Yang, Chundi Xiu, Jianmin Zhang, Dongkai Yang
In this paper, we present a novel method for 3D pedestrian navigation of foot-mounted inertial systems by integrating a MEMS-IMU, barometer, and permanent magnet. Zero-velocity update (ZUPT) is a well-known algorithm to eliminate the accumulated error of foot-mounted inertial systems. However, the ZUPT stance phase detector using acceleration and angular rate is threshold-based, which may cause incorrect stance phase estimation in the running gait pattern. A permanent magnet-based ZUPT detector is introduced to solve this problem...
November 22, 2017: Sensors
https://www.readbyqxmd.com/read/29165288/treatment-related-noncontiguous-radiologic-changes-in-children-with-diffuse-intrinsic-pontine-glioma-treated-with-expanded-irradiation-fields-and-antiangiogenic-therapy
#9
Zoltan Patay, Thomas E Merchant, Rosa Nguyen, Christopher R Pierson, Arzu Onar-Thomas, Alberto Broniscer
PURPOSE: We previously reported the cases of 3 children with diffuse intrinsic pontine glioma (DIPG) in whom noncontiguous treatment-related abnormalities (NCTRAs) developed in the brain after expanded-field radiation therapy (RT). To investigate the occurrence and putative mechanism of NCTRAs, we reviewed brain magnetic resonance imaging studies of patients with DIPG treated in 2 consecutive phase I clinical trials (trials 1 and 2). METHODS AND MATERIALS: The 55 children included in these trials received small-molecule inhibitors: vandetanib in trial 1 (n=32; mean age 6...
December 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/29165241/lifting-the-veil-on-the-dynamics-of-neuronal-activities-evoked-by-transcranial-magnetic-stimulation
#10
Bingshuo Li, Juha P Virtanen, Axel Oeltermann, Cornelius Schwarz, Martin A Giese, Ulf Ziemann, Alia Benali
Transcranial magnetic stimulation (TMS) is a widely used non-invasive tool to study and modulate human brain functions. However, TMS-evoked activity of individual neurons has remained largely inaccessible due to the large TMS-induced electromagnetic fields. Here we present a general method providing direct in vivo electrophysiological access to TMS-evoked neuronal activity 0.8-1 ms after TMS onset. We translated human single-pulse TMS to rodents and unveiled time-grained evoked activities of motor cortex layer V neurons that show high-frequency spiking within the first 6 ms depending on TMS-induced current orientation and a multiphasic spike-rhythm alternating between excitation and inhibition in the 6-300 ms epoch, all of which can be linked to various human TMS responses recorded at the level of spinal cord and muscles...
November 22, 2017: ELife
https://www.readbyqxmd.com/read/29164862/fabrication-of-magnetic-conjugation-clusters-via-intermolecular-assembling-for-ultrasensitive-surface-plasmon-resonance-spr-detection-in-wide-range-concentration
#11
Zhichao Lou, He Han, Ming Zhou, Jinfeng Wan, Qian Sun, Xiaoyan Zhou, Ning Gu
Herein, a novel sandwich surface plasmon resonance (SPR) detection assay, which utilizes prion disease-associated isoform (PrPSc) conjugating magnetic nanoparticle clusters (nanoparticle-organic clusters, NOCs) as signal amplification reagents, is constructed for ultrasensitive detection of PrPSc. Due to the highly specific affinity of aptamer-Fe3O4 nanoparticles (AMNPs) towards PrPSc and the intermolecular assembly behaviors among PrPSc, PrPSc conjugating magnetic nanoparticle clusters were obtained after the incubation of AMNPs and PrPSc, and the subsequent concentration processes in an external magnetic field...
November 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29164651/jaw-closing-movement-and-sex-differences-in-temporomandibular-joint-energy-densities
#12
Luigi M Gallo, Nicolas Fankhauser, Yoly M Gonzalez, Hongzeng Liu, Ying Liu, Jeffrey C Nickel, Laura R Iwasaki
Energy densities (ED, mJ/mm(3) ) quantify mechanical work imposed on articular cartilages during function. This cross-sectional study examined differences in temporomandibular joint (TMJ) ED during asymmetric versus symmetric jaw closing in healthy females versus males. ED component variables were tested for differences between and within sexes for two types of jaw closing. Seventeen female and 17 male subjects gave informed consent to participate. Diagnostic Criteria for Temporomandibular Disorders and images (magnetic resonance (MR), computed tomography) were used to confirm healthy TMJ status...
November 21, 2017: Journal of Oral Rehabilitation
https://www.readbyqxmd.com/read/29164453/enhancing-the-sensitivity-of-multidimensional-nmr-experiments-by-using-triply-compensated-%C3%AF-pulses
#13
Youlin Xia, Paolo Rossi, Manu V Subrahmanian, Chengdong Huang, Tamjeed Saleh, Cristina Olivieri, Charalampos G Kalodimos, Gianluigi Veglia
In multidimensional solution NMR experiments, π pulses are used extensively for inversion and refocusing operations on (1)H, (13)C and (15)N nuclei. Pulse miscalibration, off-resonance effects, and J-coupling evolution during π pulse execution result in severe signal losses that are exacerbated at high magnetic fields. Here, we report the implementation of a triply-compensated π pulse (G5) optimized for both inversion and refocusing in widely used 2- and 3-dimensional experiments. By replacing most of the hard π pulses, adiabatic or composite pulses on the (1)H, (13)C and (15)N channels with G5 pulses, we obtained signal enhancements ranging from 80 to 240%...
November 21, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/29164197/theoretical-study-of-the-photothermal-behaviour-of-self-assembled-magnetic-plasmonic-chain-structures
#14
Kai Liu, Amir Mokhtare, Xiaozheng Xue, Edward P Furlani
We study the field-directed self-assembly and photothermal behavior of one-dimensional (1D) chains of core-shell Fe3O4@Au magnetic-plasmonic nanoparticles. Monte Carlo analysis is used to predict the self-assembly of the nanoparticles when they are subjected to a uniform magnetic field and confined to a fluidic nanochannel. A coupled photonic and thermodynamic analysis is performed to analyze the optical and photothermal properties of the 1D chain structures. We show for the first time that the assembled chain structures exhibit a pronounced dip in their absorption spectrum at a wavelength that is strongly sensitive to changes in the refractive index of the surrounding medium...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29163915/field-deployable-quantitative-rapid-identification-of-active-ebola-virus-infection-in-unprocessed-blood
#15
Kavit Shah, Emma Bentley, Adam Tyler, Kevin S R Richards, Edward Wright, Linda Easterbrook, Diane Lee, Claire Cleaver, Louise Usher, Jane E Burton, James K Pitman, Christine B Bruce, David Edge, Martin Lee, Nelson Nazareth, David A Norwood, Sterghios A Moschos
The West African Ebola virus outbreak underlined the importance of delivering mass diagnostic capability outside the clinical or primary care setting in effectively containing public health emergencies caused by infectious disease. Yet, to date, there is no solution for reliably deploying at the point of need the gold standard diagnostic method, real time quantitative reverse transcription polymerase chain reaction (RT-qPCR), in a laboratory infrastructure-free manner. In this proof of principle work, we demonstrate direct performance of RT-qPCR on fresh blood using far-red fluorophores to resolve fluorogenic signal inhibition and controlled, rapid freeze/thawing to achieve viral genome extraction in a single reaction chamber assay...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163912/magnetically-activated-adhesives-towards-on-demand-magnetic-triggering-of-selected-polymerisation-reactions
#16
Gemma-Louise Davies, Joseph Govan, Renata Tekoriute, Raquel Serrano-García, Hugo Nolan, David Farrell, Ory Hajatpour, Yurii K Gun'ko
On-demand initiation of chemical reactions is becoming increasingly popular in many areas. The use of a magnetic field to trigger reactions is an intriguing concept, with vast potential in both research and industrial settings, though it remains a challenge as yet unsolved. Here we report the first example of on-demand magnetic activation of a polymerisation process using an anaerobic adhesive formulation as an example of this new approach toward triggering polymerisation reactions using an external magnetic field...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163884/magnetic-control-of-cellular-processes-using-biofunctional-nanoparticles
#17
REVIEW
Cornelia Monzel, Chiara Vicario, Jacob Piehler, Mathieu Coppey, Maxime Dahan
Remote control of cellular functions is a key challenge in biomedical research. Only a few tools are currently capable of manipulating cellular events at distance, at spatial and temporal scales matching their naturally active range. A promising approach, often referred to as 'magnetogenetics', is based on the use of magnetic fields, in conjunction with targeted biofunctional magnetic nanoparticles. By triggering molecular stimuli via mechanical, thermal or biochemical perturbations, magnetic actuation constitutes a highly versatile tool with numerous applications in fundamental research as well as exciting prospects in nano- and regenerative medicine...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163882/rapid-and-precise-determination-of-zero-field-splittings-by-terahertz-time-domain-electron-paramagnetic-resonance-spectroscopy
#18
Jian Lu, I Ozge Ozel, Carina A Belvin, Xian Li, Grigorii Skorupskii, Lei Sun, Benjamin K Ofori-Okai, Mircea Dincă, Nuh Gedik, Keith A Nelson
Zero-field splitting (ZFS) parameters are fundamentally tied to the geometries of metal ion complexes. Despite their critical importance for understanding the magnetism and spectroscopy of metal complexes, they are not routinely available through general laboratory-based techniques, and are often inferred from magnetism data. Here we demonstrate a simple tabletop experimental approach that enables direct and reliable determination of ZFS parameters in the terahertz (THz) regime. We report time-domain measurements of electron paramagnetic resonance (EPR) signals associated with THz-frequency ZFSs in molecular complexes containing high-spin transition-metal ions...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29161676/hydrophilic-and-positively-charged-polyethylenimine-functionalized-mesoporous-magnetic-clusters-for-highly-efficient-removal-of-pb-ii-and-cr-vi-from-wastewater
#19
Min Young Lee, Ji Hwan Lee, Jae Woo Chung, Seung-Yeop Kwak
We develop mesoporous magnetic clusters (MMCs) functionalized with hydrophilic branched polyethylenimine (b-PEI), later called b-MG, and MMCs functionalized with positively charged b-PEI (p-MG). These materials efficiently remove Pb(II) and Cr(VI) from wastewater. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and nitrogen adsorption-desorption analysis results clearly indicate that hydrophilic b-PEI and positively charged b-PEI are successfully attached to the MMC surfaces...
November 18, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/29161352/delta-rhythm-orchestrates-the-neural-activity-underlying-the-resting-state-bold-signal-via-phase-amplitude-coupling
#20
Saul Jaime, Hong Gu, Brian F Sadacca, Elliot A Stein, Jose E Cavazos, Yihong Yang, Hanbing Lu
Spontaneous ongoing neuronal activity is a prominent feature of the mammalian brain. Temporal and spatial patterns of such ongoing activity have been exploited to examine large-scale brain network organization and function. However, the neurophysiological basis of this spontaneous brain activity as detected by resting-state functional Magnetic Resonance Imaging (fMRI) remains poorly understood. To this end, multi-site local field potentials (LFP) and blood oxygenation level-dependent (BOLD) fMRI were simultaneously recorded in the rat striatum along with local pharmacological manipulation of striatal activity...
November 17, 2017: Cerebral Cortex
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