The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

M. L. Johns - One of the best experts on this subject based on the ideXlab platform.

  • early non destructive biofouling detection in spiral wound ro membranes using a mobile earth s field NMR
    Journal of Membrane Science, 2015
    Co-Authors: Einar O. Fridjonsson, S.J. Vogt, Johannes S. Vrouwenvelder, M. L. Johns
    Abstract:

    We demonstrate the use of Earth׳s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (Signal relaxation parameters T1, T2 and the total NMR Signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR Signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  • Early non-destructive biofouling detection in spiral wound RO membranes using a mobile earth׳s field NMR
    Journal of Membrane Science, 2015
    Co-Authors: Einar O. Fridjonsson, S.J. Vogt, Johannes S. Vrouwenvelder, M. L. Johns
    Abstract:

    We demonstrate the use of Earth׳s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (Signal relaxation parameters T1, T2 and the total NMR Signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR Signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

Johannes S. Vrouwenvelder - One of the best experts on this subject based on the ideXlab platform.

  • early non destructive biofouling detection in spiral wound ro membranes using a mobile earth s field NMR
    Journal of Membrane Science, 2015
    Co-Authors: Einar O. Fridjonsson, S.J. Vogt, Johannes S. Vrouwenvelder, M. L. Johns
    Abstract:

    We demonstrate the use of Earth׳s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (Signal relaxation parameters T1, T2 and the total NMR Signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR Signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  • Early non-destructive biofouling detection in spiral wound RO membranes using a mobile earth׳s field NMR
    Journal of Membrane Science, 2015
    Co-Authors: Einar O. Fridjonsson, S.J. Vogt, Johannes S. Vrouwenvelder, M. L. Johns
    Abstract:

    We demonstrate the use of Earth׳s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (Signal relaxation parameters T1, T2 and the total NMR Signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR Signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

Einar O. Fridjonsson - One of the best experts on this subject based on the ideXlab platform.

  • early non destructive biofouling detection in spiral wound ro membranes using a mobile earth s field NMR
    Journal of Membrane Science, 2015
    Co-Authors: Einar O. Fridjonsson, S.J. Vogt, Johannes S. Vrouwenvelder, M. L. Johns
    Abstract:

    We demonstrate the use of Earth׳s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (Signal relaxation parameters T1, T2 and the total NMR Signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR Signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  • Early non-destructive biofouling detection in spiral wound RO membranes using a mobile earth׳s field NMR
    Journal of Membrane Science, 2015
    Co-Authors: Einar O. Fridjonsson, S.J. Vogt, Johannes S. Vrouwenvelder, M. L. Johns
    Abstract:

    We demonstrate the use of Earth׳s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (Signal relaxation parameters T1, T2 and the total NMR Signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR Signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

M.m. Fahmy - One of the best experts on this subject based on the ideXlab platform.

  • NMR Signal enhancement via a new time-frequency transform
    IEEE Transactions on Medical Imaging, 2001
    Co-Authors: O.a. Ahmed, M.m. Fahmy
    Abstract:

    In this paper, a reliable method to reduce the noise from nuclear magnetic resonance (NMR) Signals using a recently developed linear critically sampled time-frequency transform is proposed. In addition to its low computational requirements, this transform has many theoretical advantages that make it a good candidate for NMR Signal enhancement. NMR Signals in the transform domain are concentrated in a few coefficients while the noise is well distributed. Performing a thresholding technique in the transform domain, therefore, significantly enhances the Signal. A comparison with other Signal enhancement techniques shows that this technique has a superior performance, thus confirming the theoretical expectations.

  • NMR Signal enhancement via a new time-frequency transform
    2000 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.00CH37100), 2000
    Co-Authors: O.a. Ahmed, M.m. Fahmy
    Abstract:

    A reliable method to reduce the noise from nuclear magnetic resonance (NMR) Signals using a previously developed linear critically-sampled time-frequency transform is proposed. In addition to its low computational requirements, this transform has many theoretical advantages that make it a good candidate for NMR Signal enhancement. NMR Signals, in the transform domain, are concentrated in a very few number of coefficients while the noise is fairly distributed among the coefficients. Therefore, performing a thresholding technique in the transform domain significantly enhances the Signal. Comparison with other noise reduction techniques used for the same purpose showed that this technique has superior performance thus confirming the theoretical expectations.

  • ICASSP - NMR Signal enhancement via a new time-frequency transform
    2000 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.00CH37100), 2000
    Co-Authors: O.a. Ahmed, M.m. Fahmy
    Abstract:

    A reliable method to reduce the noise from nuclear magnetic resonance (NMR) Signals using a previously developed linear critically-sampled time-frequency transform is proposed. In addition to its low computational requirements, this transform has many theoretical advantages that make it a good candidate for NMR Signal enhancement. NMR Signals, in the transform domain, are concentrated in a very few number of coefficients while the noise is fairly distributed among the coefficients. Therefore, performing a thresholding technique in the transform domain significantly enhances the Signal. Comparison with other noise reduction techniques used for the same purpose showed that this technique has superior performance thus confirming the theoretical expectations.

Eduard Y Chekmenev - One of the best experts on this subject based on the ideXlab platform.

  • direct 13 c hyperpolarization of 13 c acetate by microtesla NMR Signal amplification by reversible exchange sabre
    Angewandte Chemie, 2020
    Co-Authors: Max E Gemeinhardt, Eduard Y Chekmenev, Warren S Warren, Miranda N Limbach, Thomas R Gebhardt, Clark W Eriksson, Shannon L Eriksson, Jacob R Lindale, Elysia A Goodson
    Abstract:

    Herein, we demonstrate "direct" (13) C hyperpolarization of (13) C-acetate via Signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir-IMes; [IrCl(COD)(IMes)], (IMes=1,3-bis(2,4,6-trimethylphenyl), imidazole-2-ylidene; COD=cyclooctadiene)] was first activated in the presence of an auxiliary substrate (pyridine) in alcohol. Following addition of sodium 1-(13) C-acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions of SABRE in shield enables alignment transfer to heteronuclei, SABRE-SHEATH) resulted in positive enhancements of up to approximately 100-fold in the (13) C NMR Signal compared to thermal equilibrium at 9.4 T. The present results are consistent with a mechanism of "direct" transfer of spin order from parahydrogen to (13) C spins of acetate weakly bound to the catalyst, under conditions of fast exchange with respect to the (13) C acetate resonance, but we find that relaxation dynamics at microtesla fields alter the optimal matching from the traditional SABRE-SHEATH picture. Further development of this approach could lead to new ways to rapidly, cheaply, and simply hyperpolarize a broad range of substrates (e.g. metabolites with carboxyl groups) for various applications, including biomedical NMR and MRI of cellular and in vivo metabolism.

  • NMR Signal amplification by reversible exchange of sulfur heterocyclic compounds found in petroleum
    ChemistrySelect, 2016
    Co-Authors: Roman V Shchepin, Aaron M Coffey, Eduard Y Chekmenev, Boyd M Goodson, Danila A Barskiy
    Abstract:

    NMR hyperpolarization via Signal Amplification by Reversible Exchange (SABRE) was employed to investigate the feasibility of enhancing the NMR detection sensitivity of sulfur-heterocycles (specifically 2-methylthiophene and dibenzothiophenes), a family of compounds typically found in petroleum and refined petroleum products. SABRE hyperpolarization of sulfur-heterocycles (conducted in seconds) offers potential advantages of providing structural information about sulfur-containing contaminants in petroleum, thereby informing petroleum purification and refining to minimize sulfur content in refined products such as gasoline. Moreover, NMR spectroscopy sensitivity gains endowed by hyperpolarization potentially allows for performing structural assays using inexpensive, low-magnetic-field (ca. 1 T) high-resolution NMR spectrometers ideally suited for industrial applications in the field.

  • aqueous NMR Signal enhancement by reversible exchange in a single step using water soluble catalysts
    Journal of Physical Chemistry C, 2016
    Co-Authors: Ping He, Aaron M Coffey, Kevin W Waddell, Eduard Y Chekmenev, Roman V Shchepin, Milton L Truong, Quinn A Best, Kirsten A Groome, Greg Zimay, Boyd M Goodson
    Abstract:

    Two synthetic strategies are investigated for the preparation of water-soluble iridium-based catalysts for NMR Signal amplification by reversible exchange (SABRE). In one approach, PEGylation of a variant N-heterocyclic carbene provided a novel catalyst with excellent water solubility. However, while SABRE-active in ethanol solutions, the catalyst lost activity in >50% water. In a second approach, synthesis of a novel di-iridium complex precursor where the cyclooctadiene (COD) rings have been replaced by CODDA (1,2-dihydroxy-3,7-cyclooctadiene) leads to the creation of a catalyst [IrCl(CODDA)IMes] that can be dissolved and activated in water—enabling aqueous SABRE in a single step, without need for either an organic cosolvent or solvent removal followed by aqueous reconstitution. The potential utility of the CODDA catalyst for aqueous SABRE is demonstrated with the ∼(−)32-fold enhancement of 1H Signals of pyridine in water with only 1 atm of parahydrogen.

  • hyperpolarization of neat liquids by NMR Signal amplification by reversible exchange
    Journal of Physical Chemistry Letters, 2015
    Co-Authors: Roman V Shchepin, Aaron M Coffey, Kevin W Waddell, Boyd M Goodson, Milton L Truong, Thomas Theis, Warren S Warren, Eduard Y Chekmenev
    Abstract:

    We report NMR Signal Amplification by Reversible Exchange (SABRE) hyperpolarization of the rare isotopes in “neat” liquids, each composed only of an otherwise pure target compound with isotopic natural abundance (n.a.) and millimolar concentrations of dissolved catalyst. Pyridine (Py) or Py derivatives are studied at 0.4% isotopic natural abundance 15N, deuterated, 15N enriched, and in various combinations using the SABRE-SHEATH variant (microTesla magnetic fields to permit direct 15N polarization from parahydrogen via reversible binding and exchange with an Ir catalyst). We find that the dilute n.a. 15N spin bath in Py still channels spin order from parahydrogen to dilute 15N spins, without polarization losses due to the presence of 14N or 2H. We demonstrate P15N ≈ 1% (a gain of 2900 fold relative to thermal polarization at 9.4 T) at high substrate concentrations. This fundamental finding has a significant practical benefit for screening potentially hyperpolarizable contrast agents without labeling. The ...

  • nanoscale catalysts for NMR Signal enhancement by reversible exchange
    Journal of Physical Chemistry C, 2015
    Co-Authors: Aaron M Coffey, Kevin W Waddell, Eduard Y Chekmenev, Boyd M Goodson
    Abstract:

    Two types of nanoscale catalysts were created to explore NMR Signal enhancement via reversible exchange (SABRE) at the interface between heterogeneous and homogeneous conditions. Nanoparticle and polymer comb variants were synthesized by covalently tethering Ir-based organometallic catalysts to support materials composed of TiO2/PMAA (poly(methacrylic acid)) and PVP (polyvinylpyridine), respectively, and characterized by AAS, NMR, and DLS. Following parahydrogen (pH2) gas delivery to mixtures containing one type of “nano-SABRE” catalyst particle, a target substrate, and ethanol, up to ∼(−)40-fold and ∼(−)7-fold 1H NMR Signal enhancements were observed for pyridine substrates using the nanoparticle and polymer comb catalysts, respectively, following transfer to high field (9.4 T). These enhancements appear to result from intact particles and not from any catalyst molecules leaching from their supports; unlike the case with homogeneous SABRE catalysts, high-field (in situ) SABRE effects were generally not o...