Speciation of Phosphorus in Pet Foods by Solid-State P-MAS-NMR Spectroscopy.

Solid-state magic angle spinning P NMR spectroscopy is used to identify and quantify phosphorus-containing species in pet foods. The measurement is challenging due to the long spin-lattice relaxation times (s). Data acquisition times are shortened by acquiring data with a tip angle smaller than 90° and shortening the repetition time.

Direct Crystallization of Diamine Radical Cations: Carbon-Nitrogen Bond Formation from the Reaction of Triphenylamine with TiCl , TiBr , or SnCl versus Carbon-Carbon Bond Formation with SbCl.

Direct synthesis of diamine radical cations in crystalline form proceeding through oxidation of triphenylamine followed by the formation of a new C-N bond is reported. Although the oxidative coupling of triphenylamine is well studied, diamine products are rarely captured in their radical cation state. The neutral diamine most frequently obtained from this reaction pathway is N,N,N',N'-tetraphenylbenzidine.

Background-free dual-mode optical and C magnetic resonance imaging in diamond particles.

Multimodal imaging-the ability to acquire images of an object through more than one imaging mode simultaneously-has opened additional perspectives in areas ranging from astronomy to medicine. In this paper, we report progress toward combining optical and magnetic resonance (MR) imaging in such a "dual" imaging mode. They are attractive in combination because they offer complementary advantages of resolution and speed, especially in the context of imaging in scattering environments.

Imaging Sequences for Hyperpolarized Solids.

Hyperpolarization is one of the approaches to enhance Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) signal by increasing the population difference between the nuclear spin states. Imaging hyperpolarized solids opens up extensive possibilities, yet is challenging to perform. The highly populated state is normally not replenishable to the initial polarization level by spin-lattice relaxation, which regular MRI sequences rely on.

Two-way magnetic resonance tuning and enhanced subtraction imaging for non-invasive and quantitative biological imaging.

Distance-dependent magnetic resonance tuning (MRET) technology enables the sensing and quantitative imaging of biological targets in vivo, with the advantage of deep tissue penetration and fewer interactions with the surroundings as compared with those of fluorescence-based Förster resonance energy transfer. However, applications of MRET technology in vivo are currently limited by the moderate contrast enhancement and stability of T-based MRET probes. Here we report a new two-way magnetic resonance tuning (TMRET) nanoprobe with dually activatable T and T magnetic resonance signals that is coupled with dual-contrast enhanced subtraction imaging.

Electrically Elicited Quadriceps Muscle Torque: A Comparison of 3 Waveforms.

Study Design A controlled laboratory study, with a single-blind, block-randomization crossover design. Objectives To compare the electrically elicited knee extensor torque produced by 3 clinically available waveforms: 2500-Hz burst-modulated alternating current (BMAC), 1000-Hz BMAC, and 1000-Hz burst-modulated biphasic square-wave pulsed current (BMBPC). Background Neuromuscular electrical stimulation (NMES) is the therapeutic use of electrical current to strengthen muscle.

"One-Pot" Fabrication of Highly Versatile and Biocompatible Poly(vinyl alcohol)-porphyrin-based Nanotheranostics.

Nanoparticle-based theranostic agents have emerged as a new paradigm in nanomedicine field for integration of multimodal imaging and therapeutic functions within a single platform. However, the clinical translation of these agents is severely limited by the complexity of fabrication, long-term toxicity of the materials, and unfavorable biodistributions. Here we report an extremely simple and robust approach to develop highly versatile and biocompatible theranostic poly(vinyl alcohol)-porphyrin nanoparticles (PPNs).

EPR and Structural Characterization of Water-Soluble Mn-Doped Si Nanoparticles.

Water-soluble poly(allylamine) Mn-doped Si (Si) nanoparticles (NPs) were prepared and show promise for biologically related applications. The nanoparticles show both strong photoluminescence and good magnetic resonance contrast imaging. The morphology and average diameter were obtained through transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM); spherical crystalline Si NPs with an average diameter of 4.

A Metal-Free Method for Producing MRI Contrast at Amyloid-β.

Alzheimer's disease (AD) is characterized by depositions of the amyloid-β (Aβ) peptide in the brain. The disease process develops over decades, with substantial neurological loss occurring before a clinical diagnosis of dementia can be rendered. It is therefore imperative to develop methods that permit early detection and monitoring of disease progression.

Fluorescent Formazans and Tetrazolium Salts - Towards Fluorescent Cytotoxicity Assays.

Formazan-based colorimetric cytotoxicity assays, such as the MTT assay, are typically used to assess cell viability with only metabolically active cells reducing tetrazolium salts into the formazans, which is then quantified by absorbance. Fluorescence offers several advantages compared to colorimetric assays and would enable techniques such as flow cytometry and confocal microscopy to be used for analysis. Here, fluorescent formazans 10, 11 and 12, and their corresponding tetrazolium salts 13, 16 and 24, respectively, were synthesised by incorporation of a known fluorophore backbone (coumarin, fluorescein and rhodol) with disruption of the conjugated system preventing or reducing fluorescence of the tetrazolium salts.

Characterizing blood-brain barrier perturbations after exposure to human triglyceride-rich lipoprotein lipolysis products using MRI in a rat model.

Purpose: Previous studies indicated hyperlipidemia may be a risk factor for Alzheimer's disease, but the contributions of postprandial triglyceride-rich lipoprotein (TGRL) are not known. In this study, changes in blood-brain barrier diffusional transport following exposure to human TGRL lipolysis products were studied using MRI in a rat model.

Methods: Male Sprague-Dawley rats (∼180-250 g) received an i.

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia.

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-(18F)fluoro-ᴅ-glucose ([18F]FDG) uptake.

Click chemistry generated model DNA-peptide heteroconjugates as tools for mass spectrometry.

UV cross-linking of nucleic acids to proteins in combination with mass spectrometry is a powerful technique to identify proteins, peptides, and the amino acids involved in intermolecular interactions within nucleic acid-protein complexes. However, the mass spectrometric identification of cross-linked nucleic acid-protein heteroconjugates in complex mixtures and MS/MS characterization of the specific sites of cross-linking is extremely challenging. As a tool for the optimization of sample preparation, ionization, fragmentation, and detection by mass spectrometry, novel synthetic DNA-peptide heteroconjugates were generated to act as mimics of UV cross-linked heteroconjugates.

MRI measurement of blood-brain barrier transport with a rapid acquisition refocused echo (RARE) method.

Dynamic Contrast Enhanced (DCE) MRI is increasingly being used to assess changes in capillary permeability. Most quantitative techniques used to measure capillary permeability are based on the Fick equation that requires measurement of signal reflecting both plasma and tissue concentrations of the solute being tested. To date, most Magnetic Resonance Imaging (MRI) methods for acquiring appropriate data quickly rely on gradient recalled echo (GRE) type acquisitions, which work well in clinical low field settings.

Stabilizing hepatocellular phenotype using optimized synthetic surfaces.

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application.

Observation of the transition state for pressure-induced BO₃→ BO₄ conversion in glass.

A fundamental mechanistic understanding of the pressure- and/or temperature-induced facile transformation of the coordination environment of boron is important for changing the physical properties of glass. We have used in situ high-pressure (up to 2 gigapascals) boron-11 solid-state nuclear magnetic resonance spectroscopy in combination with ab initio calculations to investigate the nature of the transition state for the pressure-induced BO3→ BO4 conversion in a borosilicate glass at ambient temperature. The results indicate an anisotropic elastic deformation of the BO3 planar triangle, under isotropic stress, into a trigonal pyramid that likely serves as a precursor for the subsequent formation of a BO4 tetrahedron.

A smart and versatile theranostic nanomedicine platform based on nanoporphyrin.

Multifunctional nanoparticles with combined diagnostic and therapeutic functions show great promise towards personalized nanomedicine. However, attaining consistently high performance of these functions in vivo in one single nanoconstruct remains extremely challenging. Here we demonstrate the use of one single polymer to develop a smart 'all-in-one' nanoporphyrin platform that conveniently integrates a broad range of clinically relevant functions.

Photoluminescent carbon dots from 1,4-addition polymers.

Photoluminescent carbon dots were synthesised directly by thermopyrolysis of 1,4-addition polymers, allowing precise control of their properties. The effect of polymer composition on the properties of the carbon dots was investigated by TEM, IR, XPS, elemental analysis and fluorescence analysis, with carbon dots synthesised from nitrogen-containing polymers showing the highest fluorescence. The carbon dots with high nitrogen content were observed to have strong fluorescence in the visible region, and culture with cells showed that the carbon dots were non-cytotoxic and readily taken up by three different cell lines.

A high-pressure NMR probe for aqueous geochemistry.

A non-magnetic piston-cylinder pressure cell is presented for solution-state NMR spectroscopy at geochemical pressures. The probe has been calibrated up to 20 kbar using in situ ruby fluorescence and allows for the measurement of pressure dependencies of a wide variety of NMR-active nuclei with as little as 10 μL of sample in a microcoil. Initial (11)B NMR spectroscopy of the H3BO3-catechol equilibria reveals a large pressure-driven exchange rate and a negative pressure-dependent activation volume, reflecting increased solvation and electrostriction upon boron-catecholate formation.

The impact of alkali pretreatment and post-pretreatment conditioning on the surface properties of rice straw affecting cellulose accessibility to cellulases.

Rice straw was pretreated with sodium hydroxide and subsequently conditioned to reduce the pH to 5-6 by either: (1) extensive water washing or (2) acidification with hydrochloric acid then water washing. Alkali pretreatment improved the enzymatic digestibility of rice straw by increasing the cellulose accessibility to cellulases. However, acidification after pretreatment reversed the gains in cellulose accessibility to cellulases and enzymatic digestibility due to precipitation of solubilized compounds.

New shielding configurations for a simultaneous PET/MRI scanner at 7T.

Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems.

Intravenous HOE-642 reduces brain edema and Na uptake in the rat permanent middle cerebral artery occlusion model of stroke: evidence for participation of the blood-brain barrier Na/H exchanger.

Cerebral edema forms in the early hours of ischemic stroke by processes involving increased transport of Na and Cl from blood into brain across an intact blood-brain barrier (BBB). Our previous studies provided evidence that the BBB Na-K-Cl cotransporter is stimulated by the ischemic factors hypoxia, aglycemia, and arginine vasopressin (AVP), and that inhibition of the cotransporter by intravenous bumetanide greatly reduces edema and infarct in rats subjected to permanent middle cerebral artery occlusion (pMCAO). More recently, we showed that BBB Na/H exchanger activity is also stimulated by hypoxia, aglycemia, and AVP.

Magnetic resonance thermal imaging combined with SMASH navigators in the presence of motion.

This study develops and tests an MR thermometry method combined with SMASH navigators in phantom experiments mimicking human liver motion with the purpose of detecting and correcting motion artifacts in thermal MR images. Experimental data were acquired on a 3T MRI scanner. Motion artifacts of mobile phantoms mimicking human liver motion were detected and corrected using the SMASH navigators and then MR temperature maps were obtained using a proton resonant frequency (PRF) shift method with complex image subtraction.

Magnetic resonance thermometry at 7T for real-time monitoring and correction of ultrasound induced mild hyperthermia.

While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (≥7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition.