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https://www.readbyqxmd.com/read/28534571/toward-high-resolution-nmr-spectroscopy-of-microscopic-liquid-samples
#1
Mark C Butler, Hardeep S Mehta, Ying Chen, Patrick N Reardon, Ryan S Renslow, Michael Khbeis, Duane Irish, Karl T Mueller
A longstanding limitation of high-resolution NMR spectroscopy is the requirement for samples to have macroscopic dimensions. Commercial probes, for example, are designed for volumes of at least 5 μL, in spite of decades of work directed toward the goal of miniaturization. Progress in miniaturizing inductive detectors has been limited by a perceived need to meet two technical requirements: (1) minimal separation between the sample and the detector, which is essential for sensitivity, and (2) near-perfect magnetic-field homogeneity at the sample, which is typically needed for spectral resolution...
May 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28524683/return-to-the-origin-as-a-probe-of-atomic-phase-coherence
#2
Clément Hainaut, Isam Manai, Radu Chicireanu, Jean-François Clément, Samir Zemmouri, Jean Claude Garreau, Pascal Szriftgiser, Gabriel Lemarié, Nicolas Cherroret, Dominique Delande
We report on the observation of the coherent enhancement of the return probability ["enhanced return to the origin" (ERO)] in a periodically kicked cold-atom gas. By submitting an atomic wave packet to a pulsed, periodically shifted, laser standing wave, we induce an oscillation of ERO in time that is explained in terms of a periodic, reversible dephasing in the weak-localization interference sequences responsible for ERO. Monitoring the temporal decay of ERO, we exploit its quantum-coherent nature to quantify the decoherence rate of the atomic system...
May 5, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28522299/most-advisable-strategy-in-search-of-asymptomatic-target-organ-damage-in-hypertensive-patients
#3
J Abellán-Huerta, L Prieto-Valiente, L Consuegra-Sánchez, S Montoro-García, A B Salguero-Merino, R Morales-López, J Abellán-Alemán, F Soria-Arcos
OBJECTIVE: To evaluate the diagnostic potential of seven examinations in order to define the most suitable strategy for target organ damage (TOD) search in hypertensive patients. METHODS: This is a descriptive, cross-sectional study. 153 consecutive treated and essential hypertensive patients were enrolled. Patients with established cardiovascular or chronic renal disease (stage ≥4) were excluded. TOD search was assessed by: glomerular filtration rate (GFR), albumin/creatinine ratio (ACR), electrocardiogram (ECG), echocardiogram (ECO), ankle-brachial index (ABI), pulse wave velocity (PWV), and carotid ultrasound (intima media thickness and presence of plaques)...
May 15, 2017: Hipertensión y Riesgo Vascular
https://www.readbyqxmd.com/read/28516482/multiple-boli-arterial-spin-labeling-for-high-signal-to-noise-rodent-brain-perfusion-imaging
#4
Antoine Vallatos, Lesley Gilmour, Anthony J Chalmers, William M Holmes
PURPOSE: A systematic method is proposed for optimizing a promising preclinical arterial spin labeling (ASL) sequence based on the use of a train of adiabatic radiofrequency pulses labeling successive boli of blood water. METHODS: The sequence optimization is performed and evaluated using brain imaging experiments in mice and in rats. It involves the investigation of several parameters, ranging from the number of adiabatic pulses and labeling duration to the properties of the adiabatic hyperbolic secant pulses (ie, amplitude and frequency modulation)...
May 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28516050/towards-mri-temperature-mapping-in-real-time-the-proton-resonance-frequency-method-with-undersampled-radial-mri-and-nonlinear-inverse-reconstruction
#5
Zhongshuai Zhang, Thomas Michaelis, Jens Frahm
BACKGROUND: Optimal control of minimally invasive interventions by hyperthermia requires dynamic temperature mapping at high temporal resolution. METHODS: Based on the temperature-dependent shift of the proton resonance frequency (PRF), this work developed a method for real-time MRI thermometry which relies on highly undersampled radial FLASH MRI sequences with iterative image reconstruction by regularized nonlinear inversion (NLINV). As a first step, the method was validated with use of a temperature phantom and ex vivo organs (swine kidney) subjected to heating by warm water or a pulsed laser source...
April 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28516049/analysis-of-phase-error-effects-in-multishot-diffusion-prepared-turbo-spin-echo-imaging
#6
Anh T Van, Barbara Cervantes, Hendrik Kooijman, Dimitrios C Karampinos
BACKGROUND: To characterize the effect of phase errors on the magnitude and the phase of the diffusion-weighted (DW) signal acquired with diffusion-prepared turbo spin echo (dprep-TSE) sequences. METHODS: Motion and eddy currents were identified as the main sources of phase errors. An analytical expression for the effect of phase errors on the acquired signal was derived and verified using Bloch simulations, phantom, and in vivo experiments. RESULTS: Simulations and experiments showed that phase errors during the diffusion preparation cause both magnitude and phase modulation on the acquired data...
April 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28514847/electric-field-assisted-assembly-of-colloidal-particles-into-ordered-non-close-packed-arrays
#7
Jingjing Gong, Ning Wu
Non-close packed colloidal arrays have many potential applications ranging from plasmonic sensors, light trapping for photovoltaics, to transparent electrodes. However, scalable fabrication of those structures remains a challenge. In this paper, we investigate the robustness of an electric-field assisted approach systematically. A monolayer of non-close packed crystalline array is first created under a low-frequency alternating-current electric field in solution. We then apply a sequence of direct current pulses to fix the particle array onto the substrate so that it remains intact even after both field removal and solvent evaporation...
May 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28511856/measurement-of-15-n-longitudinal-relaxation-rates-in-15-nh4-spin-systems-to-characterise-rotational-correlation-times-and-chemical-exchange
#8
D Flemming Hansen
Many chemical and biological processes rely on the movement of monovalent cations and an understanding of such processes can therefore only be achieved by characterising the dynamics of the involved ions. It has recently been shown that (15)N-ammonium can be used as a proxy for potassium to probe potassium binding in bio-molecules such as DNA quadruplexes and enzymes. Moreover, equations have been derived to describe the time-evolution of (15)N-based spin density operator elements of (15)NH4(+) spin systems...
June 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28507234/modelling-far-field-pacing-for-terminating-spiral-waves-pinned-to-ischaemic-heterogeneities-in-cardiac-tissue
#9
E Boccia, S Luther, U Parlitz
In cardiac tissue, electrical spiral waves pinned to a heterogeneity can be unpinned (and eventually terminated) using electric far field pulses and recruiting the heterogeneity as a virtual electrode. While for isotropic media the process of unpinning is much better understood, the case of an anisotropic substrate with different conductivities in different directions still needs intensive investigation. To study the impact of anisotropy on the unpinning process, we present numerical simulations based on the bidomain formulation of the phase I of the Luo and Rudy action potential model modified due to the occurrence of acute myocardial ischaemia...
June 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28506660/specific-clones-of-staphylococcus-lugdunensis-may-be-associated-with-colon-carcinoma
#10
Norihisa Noguchi, Mari Fukuzawa, Takeaki Wajima, Kaoru Yokose, Masae Suzuki, Hidemasa Nakaminami, Takashi Kawai, Fuminori Moriyasu, Masanori Sasatsu
Staphylococcus lugdunensis produces a tannase with activity that may be associated with the onset of colon carcinoma. To clarify this feature of colon carcinoma-associated S. lugdunensis, we obtained isolates from healthy subjects and patients with colon adenomas and carcinomas and analyzed their genetic backgrounds. In total, 40 S. lugdunensis isolates from 288 rectal swabs collected between 2002 and 2008 were used. These isolates were classified into four groups according to the diseases of the subjects: healthy (n=13), colon carcinoma (n=13), colon adenoma (n=9), and unknown (n=5)...
May 11, 2017: Journal of Infection and Public Health
https://www.readbyqxmd.com/read/28504937/ultrasonic-fingerprint-sensor-with-transmit-beamforming-based-on-a-pmut-array-bonded-to-cmos-circuitry
#11
Xiaoyue Jiang, Hao-Yen Tang, Yipeng Lu, Eldwin Ng, Julius Tsai, Bernhard Boser, David Horsley
In this paper, we present a single-chip 65x42 element ultrasonic pulse-echo fingerprint sensor with transmit beamforming based on piezoelectric micromachined ultrasonic transducers (PMUTs) directly bonded to a CMOS readout ASIC. The readout ASIC was realized in a standard 180 nm CMOS process with a 24V high voltage transistor option. Pulse-echo measurements are performed column-by-column in sequence using either one column or five columns to transmit the ultrasonic pulse at 20 MHz. Transmit beamforming is used to focus the ultrasonic beam at the imaging plane where the finger is located, increasing the ultrasonic pressure and narrowing the 3dB beam-width to 50 microns, a factor of 6...
May 11, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28501714/determination-of-polymer-crystallinity-by-the-multivariable-curve-resolution-method-in-13-c-solid-nmr-spectrum
#12
Xiaoyue Zhou, Kaipin Xu, Pei Ni, Qun Chen, Shanmin Zhang
Most of the polymers are composed of a crystal part, an amorphous part, and a transitional interfacial part. These components present disparate physical and chemical characteristics. However, it always suffers from peak overlapping in solid NMR spectrum in order to acquire polymer's crystallinity. The polyethylene oxide (PEO) sample was tested using the Torchia pulse sequence combined with the Multivariate Curve Resolution (MCR) method. A two dimensional CP/MAS spectrum containing spin-lattice relaxation time (T1) information was acquired...
April 27, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28497996/characterization-of-the-salmonella-enterica-serotype-isangi-isolated-from-patients-for-the-first-time-in-china
#13
Xin-Peng Li, Ri-Hong Gao, Pei-Bin Hou, Yan-Yan Ren, Hua-Ning Zhang, Kui-Ying Jiang, Yu-Zhen Chen, Zi-Gang Qi, Min Xu, Zhen-Wang Bi
No studies have reported the isolation of serotype Salmonella Isangi from cases of salmonellosis in mainland China. We investigated an outbreak of foodborne disease with salmonella and collected the samples from the patients and surplus foods. Salmonella strains were isolated and the serotype was identified according to the Kauffmann-White scheme. The relatedness of the isolates was determined using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Antimicrobial susceptibility was conducted by the broth microdilution method...
May 12, 2017: Foodborne Pathogens and Disease
https://www.readbyqxmd.com/read/28497464/in-vivo-proton-observed-carbon-edited-poce-13-c-magnetic-resonance-spectroscopy-of-the-rat-brain-using-a-volumetric-transmitter-and-receive-only-surface-coil-on-the-proton-channel
#14
Chathura Kumaragamage, Dan Madularu, Axel P Mathieu, Henk De Feyter, M Natasha Rajah, Jamie Near
PURPOSE: In vivo carbon-13 ((13) C) MR spectroscopy (MRS) is capable of measuring energy metabolism and neuroenergetics, noninvasively in the brain. Indirect ((1) H-[(13) C]) MRS provides sensitivity benefits compared with direct (13) C methods, and normally includes a (1) H surface coil for both localization and signal reception. The aim was to develop a coil platform with homogenous B1+ and use short conventional pulses for short echo time proton observed carbon edited (POCE) MRS. METHODS: A (1) H-[(13) C] MRS coil platform was designed with a volumetric resonator for (1) H transmit, and surface coils for (1) H reception and (13) C transmission...
May 12, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28493799/shear-wave-elastography-basic-physics-and-musculoskeletal-applications
#15
Mihra S Taljanovic, Lana H Gimber, Giles W Becker, L Daniel Latt, Andrea S Klauser, David M Melville, Liang Gao, Russell S Witte
In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements...
May 2017: Radiographics: a Review Publication of the Radiological Society of North America, Inc
https://www.readbyqxmd.com/read/28490008/an-uncommon-st1224-ndm-1-producing-klebsiella-pneumoniae-isolated-from-the-bloodstream-of-a-leukemia-patient-in-china
#16
Xiaoxiao Zhang, Jia Du, Cui Zhou, Jianming Cao, Hong Lu, Haiyang Liu, Wenzi Bi, Tieli Zhou
AIMS: This study aimed to analyze the clinical data and characteristics of an NDM-1 (New Delhi metallo-β-lactamase-1)-producing Klebsiella pneumoniae isolated from the bloodstream of a leukemia patient. MATERIALS AND METHODS: A retrospective analysis was used for the clinical data of the patient. The modified Hodge test (MHT) and ethylenediaminetetraacetic acid (EDTA)-disk synergy test were used for detecting metallo-β-lactamase. Antibiotic resistance was determined using the agar dilution method...
May 11, 2017: Chemotherapy
https://www.readbyqxmd.com/read/28489309/isotropic-three-dimensional-t2-mapping-of-knee-cartilage-development-and-validation
#17
Roberto Colotti, Patrick Omoumi, Gabriele Bonanno, Jean-Baptiste Ledoux, Ruud B van Heeswijk
PURPOSE: 1) To implement a higher-resolution isotropic 3D T2 mapping technique that uses sequential T2 -prepared segmented gradient-recalled echo (Iso3DGRE) images for knee cartilage evaluation, and 2) to validate it both in vitro and in vivo in healthy volunteers and patients with knee osteoarthritis. MATERIALS AND METHODS: The Iso3DGRE sequence with an isotropic 0.6 mm spatial resolution was developed on a clinical 3T MR scanner. Numerical simulations were performed to optimize the pulse sequence parameters...
May 10, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28488223/ultrasonic-identification-of-pump-twin-by-dual-gate-doppler-in-a-monochorionic-triamniotic-triplet-twin-reversed-arterial-perfusion-sequence-before-preventative-radiofrequency-ablation-a-case-report
#18
Yuichiro Takahashi, Shigenori Iwagaki, Rika Chiaki, Kazuhiko Asai, Masako Matsui, Ichiro Kawabata
We performed a dual-gate Doppler examination for a twin reversed arterial perfusion (TRAP) sequence in a monochorionic-triamniotic triplet pregnancy at 16 weeks of gestation and were able to identify the pump twin by arterial pulse rate synchronicity. We performed radiofrequency ablation to coagulate blood flow in the acardius at 16 weeks of gestation without any postoperative complication. At 29 weeks of gestation, we performed a cesarean section due to preterm rupture of the membranes and the patient delivered 1167/1237-g female neonates and a macerated acardius...
May 9, 2017: Journal of Medical Ultrasonics
https://www.readbyqxmd.com/read/28480603/a-single-shot-t2-mapping-protocol-based-on-echo-split-gradient-spin-echo-acquisition-and-parametric-multiplexed-sensitivity-encoding-based-on-projection-onto-convex-sets-reconstruction
#19
Mei-Lan Chu, Hing-Chiu Chang, Koichi Oshio, Nan-Kuei Chen
PURPOSE: To develop a high-speed T2 mapping protocol that is capable of accurately measuring T2 relaxation time constants from a single-shot acquisition. THEORY: A new echo-split single-shot gradient-spin-echo (GRASE) pulse sequence is developed to acquire multicontrast data while suppressing signals from most nonprimary echo pathways in Carr-Purcell-Meiboom-Gill (CPMG) echoes. Residual nonprimary pathway signals are taken into consideration when performing T2 mapping using a parametric multiplexed sensitivity encoding based on projection onto convex sets (parametric-POCSMUSE) reconstruction method that incorporates extended phase graph modeling of GRASE signals...
May 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28479813/dilated-virchow-robin-spaces-mimicking-a-brainstem-arteriovenous-malformation
#20
Thomas J Buell, Arjun Ramesh, Dale Ding, Daniel M S Raper, Ching-Jen Chen, Robert M Starke, Sugoto Mukherjee, R Webster Crowley
Virchow-Robin spaces (VRS) are ubiquitous and commonly observed as the resolution of magnetic resonance imaging (MRI) continues to improve. The function of VRS and the etiology of their dilation is still a subject of research. Diagnosing dilated VRS (dVRS) can be challenging because they may appear similar to other pathologies such as cystic neoplasms, infectious cysts, and even arteriovenous malformations (AVMs) on certain MRI pulse sequences. We reported a unique case of brainstem dVRS mimicking an AVM. Furthermore, the extensive pontine involvement of our patient's lesion is rarely described in neurosurgical literature...
April 2017: Journal of Neurosciences in Rural Practice
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