57,184 results match your criteria relaxation times


Relaxation time of brain tissue in the elderly assessed by synthetic MRI.

Brain Behav 2021 Dec 4:e2449. Epub 2021 Dec 4.

Division of Neuroradiology, Department of Diagnostics, Geneva University Hospitals, Geneva, Switzerland.

Background: Synthetic MRI (SyMRI) is a quantitative technique that allows measurements of T1 and T2 relaxation times (RTs). Brain RT evolution across lifespan is well described for the younger population. The aim was to study RTs of brain parenchyma in a healthy geriatric population in order to define the normal value of structures in this group population. Read More

View Article and Full-Text PDF
December 2021

Nuclear Spin Relaxation in Viscous Liquids: Relaxation Stretching of Single-Particle Probes.

J Phys Chem B 2021 Dec 3. Epub 2021 Dec 3.

Anorganische Chemie III and Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany.

Spin-lattice relaxation rates (ω,), probed via high-field and field-cycling nuclear magnetic resonance (NMR), are used to test the validity of frequency-temperature superposition (FTS) for the reorientation dynamics in viscous liquids. For several liquids, FTS is found to apply so that master curves can be generated. The susceptibility spectra are highly similar to those obtained from depolarized light scattering (DLS) and reveal an excess wing. Read More

View Article and Full-Text PDF
December 2021

Towards Glasses with Permanent Stability.

Phys Rev Lett 2021 Nov;127(21):215501

Department of Fundamental Engineering, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.

Unlike crystals, glasses age or devitrify over time, reflecting their nonequilibrium nature. This lack of stability is a serious issue in many industrial applications. Here, we show by numerical simulations that the devitrification of quasi-hard-sphere glasses is prevented by suppressing volume-fraction inhomogeneities. Read More

View Article and Full-Text PDF
November 2021

A Type I Collagen-Targeted MR Imaging Probe for Staging Fibrosis in Crohn's Disease.

Front Mol Biosci 2021 11;8:762355. Epub 2021 Nov 11.

Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.

Fibrostenosis is a serious complication of Crohn's disease (CD), affecting approximately one-half of all patients. Surgical resection is the typical clinical end due to ineffective antifibrotic therapy mainly through anti-inflammatory treatment and fibrosis can be reverted only at early stages. Mover, human fibrotic disorders is known to be associated with aging process. Read More

View Article and Full-Text PDF
November 2021

Tracking deep-sea internal wave propagation with a differential pressure gauge array.

Sci Rep 2021 Dec 2;11(1):23311. Epub 2021 Dec 2.

Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan, ROC.

Temperature is used to trace ocean density variations, and reveals internal waves and turbulent motions in the deep ocean, called 'internal motions.' Ambient temperature detected by geophysical differential pressure gauges (DPGs) may provide year-long, complementary observations. Here, we use data from four DPGs fixed on the ocean bottom and a high-resolution temperature sensor (T-sensor) 13 m above the seafloor as a square-kilometer array deployed offshore ~ 50 km east of Taiwan facing the open Pacific Ocean to examine the impact of temperature on DPG signals related to internal motions. Read More

View Article and Full-Text PDF
December 2021

Engineering chitosan nano-cocktail containing iron oxide and ceria: A two-in-one approach for treatment of inflammatory diseases and tracking of material delivery.

Mater Sci Eng C Mater Biol Appl 2021 Dec 18;131:112477. Epub 2021 Oct 18.

Queensland Micro- and Nanotechnology Centre, Griffith University, Brisbane 4111, Australia; Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane 4072, Australia; School of Environment and Science, Griffith University, Brisbane 4111, Australia. Electronic address:

In this study, modular two-in-one nano-cocktails were synthesised to provide treatment of inflammatory diseases and also enable tracking of their delivery to the disease sites. Chitosan nano-cocktails loaded with treatment module (cerium oxide nanoparticles) and imaging module (iron oxide nanoparticles) were synthesised by electrostatic self-assembly (Chit-IOCO) and ionic gelation method (Chit-TPP-IOCO), respectively. Their MRI capability, anti-inflammatory and anti-fibrosis ability were investigated. Read More

View Article and Full-Text PDF
December 2021

Axonal T estimation using the spherical variance of the strongly diffusion-weighted MRI signal.

Magn Reson Imaging 2021 Nov 29. Epub 2021 Nov 29.

Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark; Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital - Amager and Hvidovre, Copenhagen, Denmark. Electronic address:

In magnetic resonance imaging, the application of a strong diffusion weighting suppresses the signal contributions from the less diffusion-restricted constituents of the brain's white matter, thus enabling the estimation of the transverse relaxation time T that arises from the more diffusion-restricted constituents such as the axons. However, the presence of cell nuclei and vacuoles can confound the estimation of the axonal T, as diffusion within those structures is also restricted, causing the corresponding signal to survive the strong diffusion weighting. We devise an estimator of the axonal T based on the directional spherical variance of the strongly diffusion-weighted signal. Read More

View Article and Full-Text PDF
November 2021

Following Molecular Mobility during Chemical Reactions: No Evidence for Active Propulsion.

J Am Chem Soc 2021 Dec 2. Epub 2021 Dec 2.

School of Chemistry, UNSW Sydney, Sydney, NSW 2052, Australia.

The reported changes in self-diffusion of small molecules during reactions have been attributed to "boosted mobility". We demonstrate the critical role of changing concentrations of paramagnetic ions on nuclear magnetic resonance (NMR) signal intensities, which led to erroneous measurements of diffusion coefficients. We present simple methods to overcome this problem. Read More

View Article and Full-Text PDF
December 2021

Two-Step Aging of Highly Polar Glass.

J Phys Chem Lett 2021 Dec 2:11779-11783. Epub 2021 Dec 2.

August Chełkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia in Katowice, 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland.

Nonequilibrium processes, including physical aging, belong to the most challenging phenomena of glassy dynamics. One of the fundamental problems that needs clarification is the effect of material polarity on the time scale of the structural recovery of glass. The importance of this issue arises from practical applications and recent findings suggesting a substantial contribution of dipole-dipole interactions to the dielectric permittivity spectra of polar glass-formers. Read More

View Article and Full-Text PDF
December 2021

Bimodal fluorescence/magnetic resonance molecular probes with extended spin lifetimes.

Chemistry 2021 Dec 2. Epub 2021 Dec 2.

Max-Planck-Institute for Biophysical Chemistry: Max-Planck-Institut fur biophysikalische Chemie, NMR Signal Enhancement, GERMANY.

Bimodal molecular probes combining nuclear magnetic resonance (NMR) and fluorescence have been widely studied in basic science as well as clinical research. The investigation of spinphenomena holds promise to broaden the scope of available probes allowing for deeper insights into physiological processes. Here, we are introducing a class of molecules with a bimodal character with respect to fluorescence and nuclear spin singlet states. Read More

View Article and Full-Text PDF
December 2021

Detecting low blood concentrations in joints using T1 and T2 mapping at 1.5, 3, and 7 T: an in vitro study.

Eur Radiol Exp 2021 Dec 2;5(1):51. Epub 2021 Dec 2.

Department of Radiology, Division of Imaging and Oncology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.

Background: Intra-articular blood causes irreversible joint damage, whilst clinical differentiation between haemorrhagic joint effusion and other effusions can be challenging. An accurate non-invasive method for the detection of joint bleeds is lacking. The aims of this phantom study were to investigate whether magnetic resonance imaging (MRI) T1 and T2 mapping allows for differentiation between simple and haemorrhagic joint effusion and to determine the lowest blood concentration that can be detected. Read More

View Article and Full-Text PDF
December 2021

Sound emission and annihilations in a programmable quantum vortex collider.

Nature 2021 Dec 1;600(7887):64-69. Epub 2021 Dec 1.

European Laboratory for Nonlinear Spectroscopy (LENS), Sesto Fiorentino, Italy.

In quantum fluids, the quantization of circulation forbids the diffusion of a vortex swirling flow seen in classical viscous fluids. Yet, accelerating quantum vortices may lose their energy into acoustic radiations, similar to the way electric charges decelerate on emitting photons. The dissipation of vortex energy underlies central problems in quantum hydrodynamics, such as the decay of quantum turbulence, highly relevant to systems as varied as neutron stars, superfluid helium and atomic condensates. Read More

View Article and Full-Text PDF
December 2021

Positive Lusitropic Effect of Quercetin on Isolated Ventricular Myocardia from Normal and Streptozotocin-Induced Diabetic Mice.

Biol Pharm Bull 2021 ;44(12):1894-1897

Department of Pharmacology, Toho University Faculty of Pharmaceutical Sciences.

The lusitropic effect of quercetin was examined on isolated ventricular myocardial tissue preparations from normal and streptozotocin-induced diabetic mice. The time required for 90% relaxation of the myocardium, which was prolonged in the diabetic mice, was shortened by quercetin in both normal and diabetic myocardia. This effect of quercetin was completely inhibited by cyclopiazonic acid but not by SEA0400. Read More

View Article and Full-Text PDF
January 2021

Ultrafast methods for relaxation and diffusion.

Prog Nucl Magn Reson Spectrosc 2021 Oct-Dec;126-127:101-120. Epub 2021 Jul 14.

NMR Research Unit, University of Oulu, P.O. Box 3000, FIN-90014, Finland.

Relaxation and diffusion NMR measurements offer an approach to studying rotational and translational motion of molecules non-invasively, and they also provide chemical resolution complementary to NMR spectra. Multidimensional experiments enable the correlation of relaxation and diffusion parameters as well as the observation of molecular exchange phenomena through relaxation or diffusion contrast. This review describes how to accelerate multidimensional relaxation and diffusion measurements significantly through spatial encoding. Read More

View Article and Full-Text PDF

Optimization of shaped pulses for radio frequency excitation in NMR logging.

Rev Sci Instrum 2021 Nov;92(11):114502

State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.

The radio frequency (RF) excitation pulse of the nuclear magnetic resonance (NMR) logging tool can realize slice measurement by designing shaped pulses. In the case of a certain main magnetic field, the accuracy of the shaped pulse design has a very important impact on the signal-to-noise ratio (SNR) of the NMR signal and the measurement of the short relaxation signal. Hard pulse excitation will produce an undesirable infinite number of side lobes that may perturb the spins in unwanted regions. Read More

View Article and Full-Text PDF
November 2021

Nuclear magnetic resonance measurements in dynamically controlled field pulse.

Rev Sci Instrum 2021 Nov;92(11):114709

Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.

We present the architecture of the versatile nuclear magnetic resonance (NMR) spectrometer with software-defined radio technology and its application to the dynamically controlled pulsed magnetic fields. The pulse-field technology is the only solution to access magnetic fields greater than 50 T, but the NMR experiment in the pulsed magnetic field was difficult because of the continuously changing field strength. The dynamically controlled field pulse allows us to perform NMR experiment in a quasi-steady field condition by creating a constant magnetic field for a short time around the peak of the field pulse. Read More

View Article and Full-Text PDF
November 2021

The initiation of shear band formation in deformed metallic glasses from soft localized domains.

J Chem Phys 2021 Nov;155(20):204504

Material Measurement Laboratory, Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.

It has long been thought that shear band (SB) formation in amorphous solids initiates from relatively "soft" regions in the material in which large-scale non-affine deformations become localized. The test of this hypothesis requires an effective means of identifying "soft" regions and their evolution as the material is deformed to varying degrees, where the metric of "softness" must also account for the effect of temperature on local material stiffness. We show that the mean square atomic displacement on a caging timescale ⟨u⟩, the "Debye-Waller factor," provides a useful method for estimating the shear modulus of the entire material and, by extension, the material stiffness at an atomic scale. Read More

View Article and Full-Text PDF
November 2021

Nonparametric D-R-R distribution MRI of the living human brain.

Neuroimage 2021 Nov 28;245:118753. Epub 2021 Nov 28.

Department of Chemistry, Lund University, P.O.B. 124, Lund, SE 221 00, Sweden.

Diffusion-relaxation correlation NMR can simultaneously characterize both the microstructure and the local chemical composition of complex samples that contain multiple populations of water. Recent developments on tensor-valued diffusion encoding and Monte Carlo inversion algorithms have made it possible to transfer diffusion-relaxation correlation NMR from small-bore scanners to clinical MRI systems. Initial studies on clinical MRI systems employed 5D D-R and D-R correlation to characterize healthy brain in vivo. Read More

View Article and Full-Text PDF
November 2021

Studies on the Vitrified and Cryomilled Bosentan.

Mol Pharm 2021 Dec 1. Epub 2021 Dec 1.

Department of Pharmacognosy and Phytochemistry, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, ul. Jagiellonska 4, 41-200 Sosnowiec, Poland.

In this paper, several experimental techniques [X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry, Fourier transform infrared spectroscopy, and broad-band dielectric spectroscopy] have been applied to characterize the structural and thermal properties, H-bonding pattern, and molecular dynamics of amorphous bosentan (BOS) obtained by vitrification and cryomilling of the monohydrate crystalline form of this drug. Samples prepared by these two methods were found to be similar with regard to their internal structure, H-bonding scheme, and structural (α) dynamics in the supercooled liquid state. However, based on the analysis of α-relaxation times (dielectric measurements) predicted for temperatures below the glass-transition temperature (), as well as DSC thermograms, it was concluded that the cryoground sample is more aged (and probably more physically stable) compared to the vitrified one. Read More

View Article and Full-Text PDF
December 2021

Femtochemistry of bimolecular reactions from weakly bound complexes: computational study of the H + H'OD → H'OH + D or HOD + H' exchange reactions.

Phys Chem Chem Phys 2021 Dec 1. Epub 2021 Dec 1.

Department of Chemistry, Technical University of Denmark, Kemitorvet 206, 2800 Kongens Lyngby, Denmark.

A full-dimensional wavepacket propagation describing the bimolecular exchange reactions H + H'OD → H'OH + D or HOD + H' initiated by photolysis of HCl in the hydrogen-bound complex (HCl)⋯(HOD) is reported. The dynamics of this reaction is carried out with the MCTDH method on an potential energy surface (PES) of HO and the initial state is derived from the ground state wavefunction of the complex obtained by relaxation on its own electronic ground state PES. The description of the system makes use of polyspherical coordinates parametrizing a set of Radau and Jacobi vectors. Read More

View Article and Full-Text PDF
December 2021

Stress relaxation amplitude of hydrogels determines migration, proliferation, and morphology of cells in 3-D culture.

Biomater Sci 2021 Dec 1. Epub 2021 Dec 1.

Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.

The viscoelastic behavior of hydrogel matrices sensitively influences the cell behavior in 3-D culture and biofabricated tissue model systems. Previous reports have demonstrated that cells tend to adhere, spread, migrate and proliferate better in hydrogels with pronounced stress relaxation. However, it is currently unknown if cells respond more sensitively to the amplitude of stress relaxation, or to the relaxation time constant. Read More

View Article and Full-Text PDF
December 2021

Dual fluorescence of 2-(2'-hydroxyphenyl) benzoxazole derivatives the branched decays from the upper excited-state.

Phys Chem Chem Phys 2021 Dec 1. Epub 2021 Dec 1.

Institute of Molecular Sciences and Engineering, Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao 266237, P. R. China.

As a special fluorescence phenomenon, double fluorescence has been widely developed and applied in various fields. Nevertheless, most of the research on fluorescence emission channels focuses on the first excited state, while the research on how to control the fluorescence emission channel through the upper excited state is relatively under-explored. Here, we use the time-dependent density functional theory method and consider the 2-(2'-hydroxyphenyl) benzoxazole (HBO) derivative system as an example to study the effect of upper excited states on double fluorescence. Read More

View Article and Full-Text PDF
December 2021

Comparison of the Effects of Myotherapy in Patients with Myofascial Pain with and without Self-Reported Sleep Bruxism Using The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I Questionnaire.

Med Sci Monit 2021 Dec 1;27:e934917. Epub 2021 Dec 1.

Dempartment of Temporomandibular Disorders, University of Medical Sciences, Poznań, Poland.

BACKGROUND This study aimed to compare the effects of myotherapy using sublingual relaxation splints and stretching exercises in 110 patients with myofascial pain with and without self-reported sleep bruxism using The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I Questionnaire. MATERIAL AND METHODS The study involved 110 patients with myofascial pain. The diagnosis was based on the RDC/TMD questionnaire. Read More

View Article and Full-Text PDF
December 2021

Evidence That Hypothalamic Gliosis Is Related to Impaired Glucose Homeostasis in Adults With Obesity.

Diabetes Care 2021 Nov 30. Epub 2021 Nov 30.

Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA

Objective: Preclinical research implicates hypothalamic glial cell responses in the pathogenesis of obesity and type 2 diabetes (T2D). In the current study we sought to translate such findings to humans by testing whether radiologic markers of gliosis in the mediobasal hypothalamus (MBH) were greater in individuals with obesity and impaired glucose homeostasis or T2D.

Research Design And Methods: Using cross-sectional and prospective cohort study designs, we applied a validated quantitative MRI approach to assess gliosis in 67 adults with obesity and normal glucose tolerance, impaired glucose tolerance (IGT), or T2D. Read More

View Article and Full-Text PDF
November 2021

Mechanical characterisation of hydrophobic and hydrophilic acrylates used in intraocular lenses through depth sensing indentation.

J Mech Behav Biomed Mater 2021 Nov 25:104997. Epub 2021 Nov 25.

Durability and Mechanical Integrity of Structural Materials, Rey Juan Carlos University, Spain. Electronic address:

In this work, the mechanical behaviour of hydrophilic and hydrophobic acrylates has been characterised by depth sensing indentation. Time-dependent behaviour has been studied using load-relaxation tests. Experiments have been simulated with a finite element software using a visco-hyperelastic material model. Read More

View Article and Full-Text PDF
November 2021

The impact of height on the spread of spinal anesthesia and stress response in parturients undergoing caesarean section: a prospective observational study.

BMC Anesthesiol 2021 Nov 30;21(1):298. Epub 2021 Nov 30.

Department of Anesthesiology and Perioperative Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9# Jinsui Road, Tianhe district, Guangzhou, 510623, China.

Background: The spread of spinal anesthesia was influenced by many factors, and the effect of body height on spinal anesthesia is still arguable. This study aimed to explore the impact of height on the spread of spinal anesthesia and the stress response in parturients.

Methods: A total of ninety-seven parturients were allocated into two groups according to their height: the shorter group (body height was shorter than 158 cm) and taller group (body height was taller than 165 cm). Read More

View Article and Full-Text PDF
November 2021

Stress relaxation of porcine tendon under simulated biological environment: experiment and modeling.

Acta Bioeng Biomech 2021 ;23(1):59-68

Cracow University of Technology, Faculty of Mechanical Engineering, Department of Applied Mechanics and Biomechanics, Kraków, Poland.

Purpose: The aim of the study was to investigate the viscoelastic response in the low and high physiological strain with the use of experimental and modeling approach.

Methods: Viscoelastic response in the low, transition and high physiologic strain (3, 6 and 9%) with consideration of simulated biological environment (0.9% saline solution, 37 °C) was measured in relaxation tests. Read More

View Article and Full-Text PDF
January 2021

Redox conditions correlated with vibronic coupling modulate quantum beats in photosynthetic pigment-protein complexes.

Proc Natl Acad Sci U S A 2021 Dec;118(49)

Department of Chemistry, The University of Chicago, Chicago, IL, 60637;

Quantum coherences, observed as time-dependent beats in ultrafast spectroscopic experiments, arise when light-matter interactions prepare systems in superpositions of states with differing energy and fixed phase across the ensemble. Such coherences have been observed in photosynthetic systems following ultrafast laser excitation, but what these coherences imply about the underlying energy transfer dynamics remains subject to debate. Recent work showed that redox conditions tune vibronic coupling in the Fenna-Matthews-Olson (FMO) pigment-protein complex in green sulfur bacteria, raising the question of whether redox conditions may also affect the long-lived (>100 fs) quantum coherences observed in this complex. Read More

View Article and Full-Text PDF
December 2021

Interventions for the management of abdominal pain in Crohn's disease and inflammatory bowel disease.

Cochrane Database Syst Rev 2021 11 29;11:CD013531. Epub 2021 Nov 29.

College of Health, Medicine and Life Sciences, Brunel University London, London, UK.

Background: Crohn's disease is a remitting and relapsing disorder that can affect the whole gastrointestinal tract. Active disease symptoms include abdominal pain, fatigue, weight loss, and diarrhoea. There is no known cure; however, the disease can be managed, and therefore places a huge financial burden on healthcare systems. Read More

View Article and Full-Text PDF
November 2021

A method for T and T relaxation times validation and harmonization as a support to MRI mapping.

J Magn Reson 2021 Nov 20;334:107110. Epub 2021 Nov 20.

ASST Grande Ospedale Metropolitano Niguarda, Department of Medical Physics, P.zza Ospedale Maggiore 3, 20162 Milan, Italy; University of Milan, Department of Physics, Via Celoria 16, 20133 Milan, Italy. Electronic address:

We present a proof-of-concept study focusing on a method for the intra- and inter-center validation and harmonization of data obtained from MRI T and T maps. The method is based on a set of MnCl samples that provide in-scan ground-truth reference values regardless of the details of the MRI protocol. The relaxation times of MnCl aqueous solutions were first measured by means of an NMR laboratory relaxometer, as a function of concentration and temperature. Read More

View Article and Full-Text PDF
November 2021