Eddy Walther Hansen

• Hansen, Eddy Walther (2023). Probing the “Dead-Time” in NMR by Combining Single Pulse and Solid Echo Experiments Followed by a Global Model Fit Analysis. Applied Magnetic Resonance. ISSN 0937-9347. doi: 10.1007/s00723-023-01637-5. Full text in Research Archive Show summary

  The main question addressed in this work is how to probe the “effective dead-time” in an NMR instrument, i.e., the time needed to blank the receiver after an rf-pulse excitation to prevent damage to the receiver and to avoid any distortion of the NMR signal being sampled. The strategy is to design a suitable FID-model to fit the single pulse excitation (SPE) and solid echo pulse (SEPS) data (on solid Tricosane) using a Global model-fit analysis technique. The derived dead time is discussed with respect to sampling temperature (25–40 °C) and—in particular—with respect to the number of SEPS data involved in the Global fit analysis by applying the Bayesian Information Criterion (BIC) in combination with more traditional statistical analysis. It is concluded that the “effective dead time” can be determined within a standard error of less than 2.5%.

• Hansen, Eddy Walther & Hassani, Alireza (2021). Quantitative Evaluation of Phase Distribution in UHMWPE as Derived from a Combined Use of NMR FID Analysis and Monte Carlo Simulation. Applied Magnetic Resonance. ISSN 0937-9347. p. 1–23. doi: 10.1007/s00723-021-01456-6. Full text in Research Archive Show summary

  Abstract A new and robust statistical approach is explored with the objective to derive quantitative and reliable information on the molecular dynamics within distinct domains (crystalline, intermediate and amorphous domains) of ultra-high molecular weight polyethylene (UHMWPE). The method consists of a critical evaluation of the free induction decay (FID) model, which is used to generate synthetic FID with a predefined signal-to-noise ratio by Monte Carlo simulations. The application of the method is demonstrated for three UHMWPE samples. A subsequent model fitting of their synthetic FIDs revealed a unique correlation between the error, i.e., standard deviation, of the derived parameters and the FID signal-to-noise ratio (SNR FID ). Moreover, it was found that the method can be used to estimate the minimum required sampling time to obtain reliable parameter estimation of the FID model to experimental data.

• Lerum, Hans Vigeland; Andersen, Niels Højmark; Eriksen, Dag Øistein; Hansen, Eddy Walther & Omtvedt, Jon Petter (2020). NMR study of the influence and interplay of water, HCl and LiCl with the extraction agent Aliquat 336 dissolved in toluene. Journal of Molecular Liquids. ISSN 0167-7322. 317. doi: 10.1016/j.molliq.2020.114160. Full text in Research Archive
• Wang, Jiachen; Xue, Hongjuan; Zhou, Bing; Yao, Ye-Feng & Hansen, Eddy Walther (2019). Interfacial water in mesopores and its implications to the surface features ? A solid state NMR study. Applied Surface Science. ISSN 0169-4332. 484, p. 1154–1160. doi: 10.1016/j.apsusc.2019.04.095. Full text in Research Archive
• Lerum, Hans Vigeland; Andersen, Niels Højmark; Eriksen, Dag Øistein; Hansen, Eddy Walther; Petersen, Dirk & Wibetoe, Grethe [Show all 7 contributors for this article] (2018). Study of Cadmium Extraction with Aliquat 336 from Highly Saline Solutions. Journal of Solution Chemistry. ISSN 0095-9782. 47(8), p. 1395–1417. doi: 10.1007/s10953-018-0795-z. Full text in Research Archive
• Zhu, Han; O'Farrell, Marion; Hansen, Eddy Walther; Andersen, Petter Vejle; Berg, Per & Egelandsdal, Bjørg Tordis (2017). The potential for predicting purge in packaged meat using low field NMR. Journal of Food Engineering. ISSN 0260-8774. 206, p. 98–105. doi: 10.1016/j.jfoodeng.2017.03.008. Full text in Research Archive Show summary

  The ability of NMR to predict purge from vacuum-packed pork that was stored for 9 days was investigated. T2 relaxation was measured at 24 h post mortem (p.m.) and again after 9 days of chilled storage. NMR measurements from day 1 p.m. were limited in predicting day-9 purge (|r| = 0.37–0.52). The root mean square error of linear regression (RMSD) for measuring day-9 purge using the relaxation time of intra-myofibrillar water (T21) measured on day 1 p.m. (r = −0.46) was 1.31% (range: 1.15–7.69% purge), corresponding to ±2.62% (2 × RMSD) prediction error of purge with 95% probability. This indicated that for purge production rate, the distribution and mobility of water in meat on day 1 p.m. may be of little relevance. Further tests were conducted to explain this poor predictability, by taking NMR measurements of water mobility and distribution made on the same meat sample (taken at 96 h p.m.) every day, during a 9-day storage period. By analyzing the T21 and T22 domains every day, it was revealed that during the first 5-day of storage, water (86%) moved from intra-myofibrillar space to extra-myofibrillar space. However, this movement did not result in detectable drip. A major liquid loss followed between days 6 and 7 and ceased day 8. This complexity of the water movement between domains during storage may explain the poor predictability of day-9 purge using NMR measurements from day 1.

• Hansen, Eddy Walther & Zhu, Han (2016). Discrete and Continuous Spin–Spin Relaxation Rate Distributions Derived from CPMG NMR Response Curves: a Comparative Analysis Exemplified by Water in Meat. Applied Magnetic Resonance. ISSN 0937-9347. 47(11), p. 1255–1272. doi: 10.1007/s00723-016-0828-y. Full text in Research Archive
• Mosquera, Carmen Stella; Hansen, Eddy Walther; Garcia-Santos, Glenda; Obregon-Neira, Nelson; Celis-Ossa, Raul Ernesto & Alberto, Carlos Gonzales-Murillo [Show all 9 contributors for this article] (2016). The effect of the soil properties on adsorption, single-point desorption, and degradation of chlorpyrifos in two agricultural soil profiles from Colombia. Soil science. ISSN 0038-075X. 181(9 and 10), p. 446–456. doi: 10.1097/SS.0000000000000174. Full text in Research Archive
• Zhu, Han; O'Farrell, Marion; Bouquet, Grégory; Lunde, Kathrine; Egelandsdal, Bjørg & Alvseike, Ole [Show all 9 contributors for this article] (2016). Evaluating nuclear magnetic resonance (NMR) as a robust reference method for online spectroscopic measurement of water holding capacity (WHC). Journal of Food Engineering. ISSN 0260-8774. 175, p. 51–57. doi: 10.1016/j.jfoodeng.2015.12.003. Full text in Research Archive Show summary

  The potential of using NMR as a reference method for WHC measurement in porcine longissimus dorsi was investigated. The accuracy of NMR when measuring small water changes was assessed in a model system and in muscles. Visible/near infrared (Vis/NIR) and X-ray were used as potential online spectroscopic methods to assess WHC on 40 muscles. Drip loss and spin–spin relaxation were also measured. Calibration models were built using partial least squares regression (PLSR) with Vis/NIR or X-ray spectra as input and NMR or drip loss values as output. The slowest spin–spin relaxation time (T22) showed higher correlation with both Vis/NIR (View the MathML sourceRCV2 = 0.66) and X-ray spectra (View the MathML sourceRCV2 = 0.76) than EZ-DripLoss values, demonstrating NMR has potential as a reference method for WHC measurement. NMR was more robust against variation along the length of the muscle when compared to the EZ-DripLoss method.

• Brod, Eva; Øgaard, Anne K. Falk; Hansen, Eddy Walther; Wragg, David; Haraldsen, Trond & Krogstad, Tore (2015). Waste products as alternative phosphorus fertilisers part I: inorganic P species affect fertilisation effects depending on soil pH. Nutrient Cycling in Agroecosystems. ISSN 1385-1314. 103(2), p. 167–185. doi: 10.1007/s10705-015-9734-1. Full text in Research Archive
• Hansen, Eddy Walther & Zhu, Han (2015). NEW INSIGHT INTO THE DYNAMICS OF WATER AND MACROMOLECULES IN MEAT DURING DRIP AS PROBED BY PROTON CPMG NMR. International Journal of Recent Research and Applied Studies. ISSN 2349-4891. 23(3), p. 207–220. Full text in Research Archive
• Hansen, Eddy Walther; Chen, Qun; Soler, Carlos Alberto Barreto; Fredriksen, Siw & Gong, Xiaoliang (2014). DISTRIBUTION OF GAUSSIAN DECAY FUNCTIONS AND ITS REPRESENTATION BY A COMPRESSED EXPONENTIAL FUNCTION (NMR HAHN-ECHO ANALYSIS OF PPC-COMPOSITES). International Journal of Research Reviews in Applied Sciences. ISSN 2076-734X. 21(2), p. 88–97. Full text in Research Archive
• Hansen, Eddy Walther; Gong, Xiaoliang & Qun, Chen (2013). Compressed Exponential Response Function Arising From a Continuous Distribution of Gaussian Decays - Distribution Characteristics. Macromolecular Chemistry and Physics. ISSN 1022-1352. 214(7), p. 844–852. doi: 10.1002/macp.201200715. Full text in Research Archive Show summary

  A compressed exponential function (CEF) is shown to be represented by a distribution of Gaussian functions. The properties and characteristics of the distribution are detailed and discussed, and are illustrated with reference to the change in the NMR spectroscopy proton Hahn echo relaxation response that takes place in a composite material (prepared by melt compounding a mixture of graphite nanoparticles and pyromellitic anhydride modified polypropylene carbonate (PPC)) during aging at 90 °C. The results show that both the width and the average value of the spin-spin relaxation rate distribution decrease during aging, suggesting that the molecular motion becomes less constrained and less heterogeneous.

• Soler, Carlos Alberto Barreto; Hansen, Eddy Walther & Fredriksen, Siw (2013). Advantages of polycarboxylic over dicarboxylic anhydrides in the melt modification of PPC. eXPRESS Polymer Letters. 7(11), p. 895–899. doi: 10.3144/expresspolymlett.2013.87. Full text in Research Archive
• Paul, Jobby; Hansen, Eddy Walther & Roots, Jaan (2013). Application of single-pulse solid-state H-1-MAS NMR to probe the oxidation products in crosslinked polyethylene: A detailed spectral analysis procedure. Polymer degradation and stability. ISSN 0141-3910. 98(1), p. 408–415. doi: 10.1016/j.polymdegradstab.2012.08.025. Full text in Research Archive
• Soler, Carlos Alberto Barreto; Proppe, Jonny; Fredriksen, Siw; Rychwalski, Rodney & Hansen, Eddy Walther (2013). Graphite nanoplatelet/pyromellitic dianhydride melt modified PPC composites: Preparation and characterization. Polymer. ISSN 0032-3861. 54(14), p. 3574–3585. doi: 10.1016/j.polymer.2013.04.068. Full text in Research Archive
• Soler, Carlos Alberto Barreto; Altskar, Annika; Fredriksen, Siw; Hansen, Eddy Walther & Rychwalski, Rodney (2013). Multiwall carbon nanotube/PPC composites: Preparation, structural analysis and thermal stability. European Polymer Journal. ISSN 0014-3057. 49(8), p. 2149–2161. doi: 10.1016/j.eurpolymj.2013.05.009. Full text in Research Archive
• Soler, Carlos Alberto Barreto; Hansen, Eddy Walther & Fredriksen, Siw (2012). Novel solventless purification of poly(propylene carbonate): Tailoring the composition and thermal properties of PPC. Polymer degradation and stability. ISSN 0141-3910. 97(6), p. 893–904. doi: 10.1016/j.polymdegradstab.2012.03.033. Full text in Research Archive
• Gong, Xiaoliang; Hansen, Eddy Walther & Chen, Qun (2012). The Scaling Law between Molecular Mass and Diffusivity and its Influence on the Molecular Weight Distribution as Derived from a Stretched Exponential PGSTE NMR Response Curve. Macromolecular Chemistry and Physics. ISSN 1022-1352. 213(23), p. 2464–2471. doi: 10.1002/macp.201200372. Full text in Research Archive
• Gong, Xiaoliang; Hansen, Eddy Walther & Chen, Qun (2012). Molecular Weight Distribution Characteristics (of a Polymer) Derived from a Stretched-Exponential PGSTE NMR Response Function - Simulation. Macromolecular Chemistry and Physics. ISSN 1022-1352. 213(3), p. 278–284. doi: 10.1002/macp.201100528. Full text in Research Archive Show summary

  Assuming the signal response in a PGSTE experiment (on a polymer) to be described by a simple Stretched-Exponential function (SEF), and knowing the scaling law between diffusivity and molecular weight, the Molecular Weight Distribution (MWD) characteristics (Kurtosis, Skewness, moment and width) are derived and compared to the corresponding distribution characteristics obtained by a Log-Normal Function fit (to the same MWD). Also, the challenge involved in obtaining a reliable weight average molecular weight from a SEF response function is discussed.

• Paul, Jobby; Hansen, Eddy Walther & Roots, Jaan (2012). Probing the molecular dynamics in XLPE aged at different temperatures by H-1 NMR relaxation time measurements. Polymer degradation and stability. ISSN 0141-3910. 97(11), p. 2403–2411. doi: 10.1016/j.polymdegradstab.2012.07.022. Full text in Research Archive
• Hansen, Eddy Walther; Jobby, Paul; Jørgensen, Sissel; Arstad, Bjørnar & Bouzga, Aud Mjærum (2011). Quantitative determination of comonomer content in ethene-1-hexene copolymers by solid state 1H-MAS NMR. International Journal of Research Reviews in Applied Sciences. ISSN 2076-734X. 6(4), p. 382–390. Full text in Research Archive Show summary

  1H-MAS NMR is shown to be a powerful and attractive technique for quantifying the comonomer content in ethene--alkene copolymers, as exemplified by a series of ethene--hexene copolymers. The main advantages of applying 1H-MAS solid-state NMR are related to; a) the very short experimental sampling time, on the order of a few minutes b) the bypass of sample preparation, as compared to traditional high-resolution liquid-state 13C-NMR which necessitates a high temperature (1300C) preparation period of days, or even weeks, c) no thermal sample treatment and d) no need for calibration. In particular, it will be shown that the technique allows the comonomer content of cross-linked LDPE to be probed, which is generally difficult, or impossible, by solution-state NMR since these polymers are mostly non-soluble.

• Gong, Xiaoliang; Hansen, Eddy Walther & Chen, Qun (2011). A Simple Access to the (Log/Normal) Molecular Weight Distribution Parameters of Polymers Using PGSTE NMR. Macromolecular Chemistry and Physics. ISSN 1022-1352. 212(10), p. 1007–1015. doi: 10.1002/macp.201000706. Full text in Research Archive Show summary

  A log-normal molecular weight distribution (LNMWD) is characterized by two parameters, the mean molecular weight and the width , where the latter is related to the polydispersity index. In this work we show how to obtain these by model fitting a stretch exponential function to the Pulsed-Gradient Stimulated Spin-Echo (PGSE) response curve where x is proportional to the square of the amplitude of the gradient pulse, DS is the diffusion coefficient of the polymer and  is the stretch exponent. Based on simulations, two general empirical equations relating andDS to and  are found: (a) (b) with a (= 0.040+0.003) and b (= 0.284 + 0.006) being constants. For practical application the model was derived for 0.5 <  <1, 0.2 <  < 1 and 5.10-12 (m2s-1) < DS < 10-10 (m2s-1) but may (easily) be extended to values outside of these regions. The model enables the LNMWD characteristics to be determined if knowing the scaling law ( ) between diffusivity D and molecular weight M. The sensitivity and relative error of  and M0 are discussed in details and the applicability of the model is illustrated by analyzing the experimental NMR response curve of three PEO samples. The advantage of this technique is its simplicity, numerical robustness and reliability.

• Mosquera, Carmen Stella; Martinez, Maria J.; Guerrero, Jairo A. & Hansen, Eddy Walther (2010). Structural Characterization of Organic Matter of three Soils from Aquitania/Boyaca, Colombia. Revista Colombiana de Quimica. ISSN 0120-2804. 39(1), p. 47–60. Full text in Research Archive Show summary

  Generally, soil organic matters may differ in structure, composition and conformation according to their origin and age. In the present work structural composition of three soil organic matters, as determined by IR and solid-state CPMAS 13C-NMR spectroscopy of two Inceptisol soils (I01 and I02) and one Histosol soil (H03) from the Aquitania-Boyacá town in Colombia are presented (in these soils farmers have grown large onion crops). Measurements were performed at two different depths 0 - 10 and 40 - 50 cm, respectively. According to the IR spectra the presence of OH-groups (from phenols, carboxylic acids and alcohols), aromatic and aliphatic groups were identified. The 13C NMR spectra revealed a decreasing amount of organic matter with increasing depth in the following relative order: H03-0=100 and H03-40= 88, I02-0=23 and I02-40=0, and finally I01-0 = 17 and I01-40 = 12. The carbon peaks resonating in the ! = 108-50 ppm region of the spectra (N- and O-alkyls and acetals) dominated in almost all the extracted soils, with aromatic carbon peaks (!=168-108 ppm) showing the second most intense peaks for the samples I01-0 and H03-40. The aliphatic carbon (! = 0-50 ppm) revealed the second most intense peaks in samples I01-40, I02-0 and H03-0. Finally, carbonyl carbon (d = 220-162 ppm) contributed the smallest signal intensity in all he three soil samples.

• Ukkelberg, Åsmund; Sørland, Heir Humborstad; Hansen, Eddy Walther & Widerøe, Hege C. (2010). ANAHESS, A NEW SECOND ORDER SUM OF EXPONENTIALS FIT ALGORITHM, COMPARED TO THE TIKHONOV REGULARIZATION APPROACH, WITH NMR APPLICATIONS. International Journal of Research Reviews in Applied Sciences. ISSN 2076-734X. 2, p. 195–2010. Full text in Research Archive
• Hansen, Eddy Walther; Chen, Qun; Peng, Min & Liu, Wei (2010). DEGRADATION RATE OF γ -POLYGLUTAMIC ACID PROBED BY 1H-NMR SPECTRAL ANALYSIS AND BY PFGSTE NMR – INTERNAL CONSISTENCY. International Journal of Research Reviews in Applied Sciences. ISSN 2076-734X. 3(3), p. 233–241. Full text in Research Archive Show summary

  Pulsed Field Gradient Stimulated Spin-Echo (PFGSTE) NMR experiments on γ -Polyglutamic Acid (γ-PGA) dissolved in D2O (pH = 3 and T = 353 K) was performed to monitor the degradation process as a function of time. After establishing the effect of molecular weight on relaxation (T1 and T2), the PFGSTE response curve (signal intensity as a function of gradient field strength squared) enabled the average or effective diffusivity to be determined, and hence the average molecular weight to be derived as a function of degradation time. The rate of degradation was determined to be KD= (2.3 + 0.4).10-2h-1. The corresponding rate determined by a single exponential (1. order rate law) fit to the time dependence of the signal intensity of resonance band δ = 4.0 – 4.1 ppm was found to be KI= (1.7 + 0.1).10-2h-1 showing that the two different and independent NMR approaches result in the same overall degradation rate. Finally, the time dependence of the PFGSTE NMR derived average molecular weight was shown to follow a random degradation process, as expected for a hydrolysis degradation process.

• Hansen, Eddy Walther & Roots, Jaan (2010). DETERMINATION OF CRYSTALLINITY IN POLYETHYLENE FROM 1H-NMR FID ANALYSIS EFFECT OF NON-CURIE TEMPERATURE BEHAVIOUR. International Journal of Research Reviews in Applied Sciences. ISSN 2076-734X. 5(3), p. 207–212. Full text in Research Archive Show summary

  Hansen and coworkers (Zhang, L; Hansen, E. W.; Helland, I; Hinrichsen, E.; Larsen, Aa.; Roots, J. Macromolecules, 2009, 42 (14), 5189-5195) recently reported on the room temperature crystallinity of a series of ethene-1-hexene copolymers using solid-state 1H-NMR FID analysis. However, due to the required 10 s blanking time of the receiver vital information in the initial part of the FID was lost resulting in an underestimation of the sample crystallinity. To compensate for this information loss we made use of the significant increase in T2 at or above the melting point which enabled the intensity of the FID at time t = 0 to be reliably estimated. Hence, by applying the Curie law the room temperature intensity of the FID was re-evaluated and resulted in an improved crystallinity value. However, it was still too small compared to the crystallinity obtained by solid-state 13C-NMR. However, by multiplying the proton FID intensity (determined at the melting point) by a factor of 1.25 before applying the Curie law, the room temperature crystallinity derived from the two different NMR techniques became – within experimental error – consistent. In this work we present experimental evidence that the empirical multiplication factor of 1.25 strictly originates from a non-Curie temperature behaviour of the NMR signal intensity.

• Xue, Minje; Chen, Qun; Shu, Jie & Hansen, Eddy Walther (2010). CHANGES IN SEGMENTAL DYNAMICS OF ISOPRENE IN STYRENE-ISOPRENE BLOCK COPOLYMERS UPON ELONGATION PROBED BYSOLID STATE CARBON NMR RELAXATION TIME MEASUREMENTS. International Journal of Research Reviews in Applied Sciences. ISSN 2076-734X. 5(2), p. 129–137. Full text in Research Archive Show summary

  The segmental motion of isoprene within styrene–isoprene tri-block (SIS) copolymers (14 wt% and 22 wt% styrene) is reported as a function of elongation at three different temperatures (293K, 303K and 313K) using carbon solid state NMR spin-spin (T2) and spin-lattice (T1) relaxation time measurements. The results show that after a sample elongation by a factor of approximately 4, the segmental mobility decreases by a factor of 2 – 3. Also, the segmental mobility reveals a temperature behaviour which is strongly dependent on the relative amount of styrene within the styrene-isoprene tri-block polymers. The activation energy of the segmental motion is further discussed with respect to the B-parameter in the Vogel-Tammann-Fulcher (VTF) Equation; log(/0) = B/(T-T0), where  is the segmental correlation time at the (absolute) temperature T.

• Zhang, Lili; Hansen, Eddy Walther; Helland, Irene; Hinrichsen, Einar; Larsen, Åge & Roots, Jaan (2009). Crystallinity in Ethene-1-Hexene Copolymers Determined by H-1 and C-13 NMR. A Comparative Study. Macromolecules. ISSN 0024-9297. 42(14), p. 5189–5195. doi: 10.1021/ma900249z. Full text in Research Archive
• Zhenlong, Jia; Zhang, Lili; Chen, Qun & Hansen, Eddy Walther (2008). Proton Spin Diffusion in Polyethylene as a Function of Magic-Angle Spinning Rate. A Phenomenological Approach. Journal of Physical Chemistry A. ISSN 1089-5639. 112, p. 1228–1233. Full text in Research Archive Show summary

  Starting from the phenomenological Bloembergen-Purcell-Pound equation a relation between magic-angle spinning (MAS) rate and spin diffusion is derived. The resulting model equation was fitted to observed spin diffusion versus MAS rate data obtained at 298 K on an high-density polyethylene sample, revealing a reduction in the effective spin diffusivity by (65 + 5)% when increasing the MAS rate from 2 to 12 kHz. The same model equation enabled the rigid-lattice diffusivity to be estimated and was found to be only slightly higher, by approximately 10%, compared to the spin diffusivity observed at the lowest MAS rate applied (2 kHz). Moreover, the model equation predicts a reduction in the effective spin diffusivity by more than 90% when increasing the MAS rate to more than 30 kHz.

• Jia, ZL; Zhang, LL; Chen, Q & Hansen, Eddy Walther (2008). Proton spin diffusion in polyethylene as a function of magic-angle spinning rate. A phenomenological approach. Journal of Physical Chemistry A. ISSN 1089-5639. 112. doi: 10.1021/jp077067u. Full text in Research Archive
• Hansen, Eddy Walther; Zhang, Lili; Chen, Qun & Liu, Z (2007). Quantitative determination of phase content in multiphase polymers by combining spin-diffusion and CP-MAS NMR. Macromolecules. ISSN 0024-9297. 40(15), p. 5411–5419. doi: 10.1021/ma0707786. Full text in Research Archive Show summary

  We present a new approach to determine quantitatively the phase content of multiphase polymers by applying a spin-diffusion pulse sequence (filter) prior to cross-polarization (CP) in a 13C-CPAS experiment. The technique is exemplified for two rather different polymer systems, a high-density polyethylene (HDPE) and four styrene-isoprene diblock copolymers, all of known phase contents. In principle, the technique should be applicable to any multiphase system in which spin-diffusion between different regions/phases exists and where the magnetization of phases can selectively be filtered out.

• Hansen, Eddy Walther; Norby, Poul; Roots, Jaan & Wu, Qinglan (2007). Gelation of Delaminated Layered Double Hydroxide Nanosheets in Formamide Probed by Proton Spin-Spin Relaxation and Pulsed Field Gradient NMR. Journal of Physical Chemistry C. ISSN 1932-7447. 111(32), p. 11854–11861. doi: 10.1021/jp072273n. Full text in Research Archive Show summary

  A colloid dispersion of exfoliated nanosheets of a layered double hydroxide (LDH-NO3) was prepared by ultrasonic treatment for 4-5 h in formamide. A slow gelation process takes place, which was followed using proton spin-spin relaxation and pulsed field gradient (PFG) NMR. On the NMR time scale, the LDH particles were considered as a nonmobile matrix surrounded by mobile formamide molecules, thus resembling a porous medium. The spatial constraints (micrometer range) imposed on the formamide molecules increase monotonically with time when the LDH particles rearrange and form a "network" during the gelation process, resulting in a faster diffusion of formamide within this "porous" medium. By combining proton NMR spin-spin relaxation rate measurements (1/T2) and PFG-NMR measurements (diffusion), the size of the spatial restrictions formed by the LDH particles was probed as a function of time. The physical model applied in the analysis is discussed in the text.

• Hansen, Eddy Walther; Realpe, Isabel Bravo & Mosquera, Carmen Stella (2007). Structural Behaviour of Human acids from Cauca Department andisol soil. Revista Colombiana de Quimica. ISSN 0120-2804. 36(1), p. 31–41. Full text in Research Archive Show summary

  Humic substances are a heterogeneous mixture of chemical compounds, where each fraction (humic acids, fulvic acids and humin) is constituted by different size molecules. Their structure depends on soil type and environmental conditions. In this study different spectroscopic techniques like; ultraviolet – visible (ratio E4/E6), infrared Fourier transform (IFT) and solid – state 13C nuclear magnetic resonance (NMR) have been used to identify the humic acids (HA) chemical structure, as well as the structural changes taking place in acetic anhydride and absolute ethanol. HA was extracted from organic matter of an Andisol soil in Cauca Department, Colombia, using three basic solutions: Na2B4O7.10H2O (0,05M), Na2P2O7.10H2O (0,05M) and NaOH (0,1M). Humic acids were purified by acid treatment, HCL – HF 1%, high speed centrifugation and dialysis. The ratio E4/E6 revealed changes on humic acids condensation degree in different chemical environment. These changes were documented by new bands appearance, as well as changes in relative signal intensity distribution of existing bands in infrared spectra. Also, differences in relative intensity distribution of the solid state 13C MAS NMR resonance bands were noticed. The present work reveals chemical and structural changes of HA obtained from an agricultural soil, and this study is concordant, respecting to different researching made in this topic.

• Hansen, Eddy Walther; Kjekshus, Arne & Odden, Jan Ove (2007). On the hydrogen in hydrogen-containing amorphous silicon. Journal of Non-Crystalline Solids. ISSN 0022-3093. 353(28), p. 2734–2743. doi: 10.1016/j.jnoncrysol.2007.05.014. Full text in Research Archive Show summary

  Abstract The present contribution reports on refined and constrained analyses of the complex proton-NMR free-induction-decay (FID) signal of hydrogen-containing amorphous silicon (a-Si:H), produced by thermal decomposition of pressurized monosilane. The spectra comprise clustered and diluted protons and the mole fractions of these are described by an algebraic sum of two exponential terms of the type I · exp(−kP) where I and k are constants and P the initial monosilane pressure in the decomposition reactor. The NMR spin–spin relaxation time of the clustered protons is found to be approximately constant (T2G ≈ 15 μs) and independent of P. For the diluted protons, the spin–spin relaxation time are found to increase monotonically with increasing P (T2L ranging from 85 to 140 μs) and could be approximated by a second-order polynomial in P. The number of diluted protons and their average nearest-neighbor separation are found to increase with increasing P from 7 Å at 0.28 MPa to 8.5 Å at 6.61 MPa. These findings show that the amorphous raw-silicon exhibits an inhomogeneous distribution of diluted protons. The distribution becomes more homogeneous with increasing P. The simplest description of the clustered configurations is that the number of protons and their average nearest-neighbor distance remain constant and independent of P, and that only the number of the clusters increases with increasing P. The amount of diluted and clustered protons, complies with the total amount of hydrogen found by chemical analysis and by FT-IR spectroscopy.

• Hansen, Eddy Walther; Kjekshus, Arne & Odden, Jan Ove (2007). On the hydrogen in hydrogen-containing amorphous silicon. Journal of Non-Crystalline Solids. ISSN 0022-3093. 353, p. 2734–2743. Full text in Research Archive Show summary

  The present contribution reports on refined and constrained analyses of the complex proton-NMR free-induction-decay (FID) signal of hydrogen-containing amorphous silicon (a-Si:H), produced by thermal decomposition of pressurized monosilane. The spectra comprise clustered and diluted protons and the mole fractions of these are described by an algebraic sum of two exponential terms of the type I center dot exp(-kP) where I and k are constants and P the initial monosilane pressure in the decomposition reactor. The NMR spin-spin relaxation time of the clustered protons is found to be approximately constant (T-2G approximate to 15 mu s) and independent of P. For the diluted protons, the spin-spin relaxation time are found to increase monotonically with increasing P (T L ranging from similar to 85 to similar to 140 mu s) and could be approximated by a second-order polynomial. in P. The number of diluted protons and their average nearest-neighbor separation are found to increase with increasing P from similar to 7 angstrom at 0.28 MPa to similar to 8.5 angstrom at 6.61 MPa. These findings show that the amorphous raw-silicon exhibits an inhomogeneous distribution of diluted protons. The distribution becomes more homogeneous with increasing P. The simplest description of the clustered configurations is that the number of protons and their average nearest-neighbor distance remain constant and independent of P, and that only the number of the clusters increases with increasing P. The amount of diluted and clustered protons, complies with the total amount of hydrogen found by chemical analysis and by FT-IR spectroscopy. (c) 2007 Elsevier B.V. All rights reserved.

• Hansen, Eddy Walther; Johannessen, Espen & Rosenholm, Jarl B. (2006). Fluid Self-Diffusion in Scots Pine Sapwood Tracheid Cells. Journal of Physical Chemistry B. ISSN 1520-6106. 110(5), p. 2427–2434. Full text in Research Archive Show summary

  The self-diffusion coefficients of water and toluene in Scots pine sapwood was measured using low field pulsed field gradient nuclear magnetic resonance (PFG-NMR). Wood chips of 8 mm diameter were saturated with the respective liquids, and liquid self-diffusion was then traced in one dimension orthogonal to the tracheid cell walls in the wood’s radial direction. The experimental echo attenuation curves were exponential, and characteristic self-diffusion coefficients were produced for diffusion times spanning from very short times to times on the order of magnitude of seconds. Observed self-diffusion coefficients were decaying asymptotically as a function of diffusion time, an effect which was ascribed to the cell walls’ restriction on confined liquid diffusion. The observed self-diffusion behavior in Scots pine sapwood was compared to self-diffusion coefficients obtained from simulations of diffusion in a square. Principles of molecular displacements in confined geometries were used for elucidating the wood’s cellular structure from the observed diffusion coefficients. The results were compared with a mathematical model for diffusion between parallel planes.

• Johannessen, Espen; Hansen, Eddy Walther & Rosenholm, Jarl B. (2006). Probing structural periodicity (annual ring size) in Scots pine by NMR profiling. Wood Science and Technology. ISSN 0043-7719. 40(7), p. 537–547. Full text in Research Archive Show summary

  The water distribution along a direction normal to the annual rings of a water-saturated sapwood sample from Scots pine (9 mm of length) was determined using NMR one-dimensional imaging. The NMR profiles were obtained at a low-field NMR instrument using pulsed field gradients in Hahn echo experiments. Using a gradient pulse of 60 G/cm, a spatial resolution of 12 lm along the axis was obtained. A subsequent Fourier analysis of the signal intensity along the specified direction enabled the size distribution of the annual rings together with the relative amount of water within the rings to be estimated. The technique is a non-damaging way to determine the annual ring profile in wood, and can be further developed as a mobile equipment for annual ring profiling of whole trees.

• Hansen, Eddy Walther; Lili, Zhang & Chen, Qun (2005). Morphology and Phae Characteristics of High-Density Polyethylene Probed by NMR Spin Diffusion and Second Momemt Analysis. Macromolecular Chemistry and Physics. ISSN 1022-1352. 206(2), p. 246–257. Full text in Research Archive
• Hansen, Eddy Walther & Gran, Hans Christian (2005). Probing Pore-Structure within Porous Polymer Particles by NMR. Diffusion Fundamentals. 3, p. 21.1–21.2. Full text in Research Archive Show summary

  How to probe pore morphology or pore-structure by combining NMR Cryoporometry and NMR relaxometry

• Hansen, Eddy Walther; Gran, Hans Christian & Johannessen, Espen (2005). Diffusion of water in cement paste probed by isotopic exchange experiments and PFG NMR. Microporous and Mesoporous Materials. ISSN 1387-1811. 78(1), p. 43–52. Full text in Research Archive
• Kortunov, P; Vasenkov, S; Karger, J; Elia, MF; Perez, M & Stocker, M [Show all 19 contributors for this article] (2005). Diffusion in fluid catalytic cracking catalysts on various displacement scales and its role in catalytic performance. Chemistry of Materials. ISSN 0897-4756. 17(9), p. 2466–2474. Full text in Research Archive
• Hansen, Eddy Walther; Johannessen, Espen & Rosenholm, Jarl B. (2005). Fluid Self-Diffusion in Scots Pine-Sapwood and Silica Wood Replicas. Diffusion Fundamentals. p. 570–571. Full text in Research Archive
• Kortunov, P.; Hansen, Eddy Walther; Vasenkov, S.; Kaerger, J.; Elia, M. & Perez, M. (2005). PFG NMR study of transport properties of FCC catalyst. Magnetic Resonance Imaging. ISSN 0730-725X. 23(2), p. 233–237. Full text in Research Archive
• Hansen, Eddy Walther; Fonnum, Geir & Weng, Ellen (2005). Pore Morphology of Porous Polymer Particles Probed by NMR Relaxometry and NMR Cryoporometry. Journal of Physical Chemistry B. ISSN 1520-6106. 109(51), p. 24295–24303. Full text in Research Archive Show summary

  The pore size distribution (PSD) and pore connectivity (PC) within porous polymer particles are probed by combining NMR-cryoporometry and NMR relaxometry (spin-spin relaxation). Using water as a probe molecule, the constant K in the so-called Gibbs-Thompson equation, as well as the surface relaxivity (&#61554;2) were determined to be K = (420 + 50) KÅ and &#61554;2 = (0.44 + 0.01).10-6 ms-1, respectively. Also, the thickness of the interface layer was estimated to be of the order of one monolayer of water molecules. A detailed analysis of the complete set of NMR data enabled the morphology, or pore structure to be probed, and is thoroughly discussed in the text.

• Hansen, Eddy Walther; Bohumil, Bernhauer & Blom, Richard (2004). Diffusion and reaction of methylaluminoxane (MAO) within a silica membrane. Macromolecular Chemistry and Physics. ISSN 1022-1352. 205, p. 1361–1368. Full text in Research Archive Show summary

  Abstract Summary: The self-diffusion coefficient of MAO confined within a silica membrane is not experimentally accessible by traditional PFG NMR measurements, probably due to a susceptibility effect resulting in rather broad, unobservable resonance lines. A more indirect approach was therefore applied to probe the diffusivity of MAO within a silica membrane. MAO confined in a bulk toluene solution on one side of the membrane was free to diffuse through the membrane (saturated with toluene) and into a corresponding deuterated toluene solution on the other side of the membrane where its proton NMR signal intensity was monitored as a function of time. By introducing a relevant diffusion model, the diffusivities of both toluene and MAO were derived by model-fitting. By refining the diffusion model, the formation of methane within the silica was explained, and its diffusivity estimated. The results suggest a significant reduction in diffusivities of both MAO and toluene within the silica as compared to the corresponding diffusivities in bulk solution.

• Hansen, Eddy Walther; Dahl, I. M.; Slagtern, Åse & Wendelbo, Rune (2003). Synthesis of SAPO-type zeolites and their use as adsorbent or catalyst for the conversion of an oxygenate hydrocarbon to olefins. PCT Int. Appl. Full text in Research Archive Show summary

  The invention concerns a simple and cheap method for production of microporous crystalline metalloaluminiumphosphates (ELAPO) for use as adsorbent or catalyst by wholly or partially filling the pores of particles containing aluminium phosphate (AIPO) with an aqueous mixture containing an active source of metal and an organic structure directing agent and perform crystallisation at elevated temperature under autogenous pressure to form crystals of ELAPO.

• Hansen, Eddy Walther; Simon, Christian R.; Haugsrud, Reidar; Raeder, Henrik & Bredesen, Rune (2002). Probing Pore Size Distribution by Cryogenic- and Relaxation 2H-NMR. Journal of Physical Chemistry B. ISSN 1520-6106. 106(48), p. 12396–12406. Full text in Research Archive
• Hansen, Eddy Walther & Gran, Hans Christian (2002). FLR-Technique. Exchange Kinetics of ethanol/fluorescent dye with water in water saturated cement paste examined by 1H and 2H-NMR. Cement and Concrete Research. ISSN 0008-8846. 32, p. 795–801. Full text in Research Archive
• Hansen, Eddy Walther; Blom, Richard & Kvernberg, Per Olav (2001). Diffusion of Methylaluminoxane (MAO) in Toluene Probed by 1H NMR Spin-Lattice Relaxation Time. Macromolecular Chemistry and Physics. ISSN 1022-1352. 202, p. 2880–2889. Full text in Research Archive
• Hansen, Eddy Walther; Kristiansen, Per eugen & Pedersen, Bjørn (2001). Isothermal Crystallization of Polyethylene Monitored by in situ solid state 1H NMR and Analyzed within the Avrami Model Framework. Polymer. ISSN 0032-3861. 42, p. 1969–1980. Full text in Research Archive
• Hansen, Eddy Walther; Bouzga, Aud. M.; Sommer, Britt & Kvernberg, Per Olav (2000). Crosslinking of PVA and Glutaraldehyde in Water Monitored by Viscosity and Pulse Field Gradient NMR: a Comparative Study. Polymers for Advanced Technologies. ISSN 1042-7147. 1(11), p. 185–191. Full text in Research Archive

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• Lehrum, Hans Vigeland; Andersen, Niels Højmark; Eriksen, Dag Øistein; Hansen, Eddy Walther & Omtvedt, Jon Petter (2020). NMR Studies of Aliquat 336 in toluene after contact with saline solutions - Determination of ionic content. Full text in Research Archive
• Alireza, Hassani; Hansen, Eddy Walther; Olsbye, Unni & Fredriksen, Siw Bodil (2020). Segmental Orientation and Mobility of Ultra-high Molecular Weight Polyethylene. Full text in Research Archive Show summary

  Abstract: Formation of entanglements in Ultra-High Molecular Weight Polyethylene (UHMWPE with average molecular weight exceeding 10^6 g.mol-1 limits their processability [1]. Entanglement characterization techniques mostly requires processing of nascent reactor powder, by melting. This will, however disturb the initial properties, and accordingly, the initial entanglement density in polymers. Therefore, Nuclear Magnetic Resonance (NMR) is an interesting alternative technique where the properties of UHMWPE can be explored in the solid state. However, during relevant NMR studies, the samples were either melted or exposed to time-intensive 13C high field NMR experiments [2]. Recently, simple low field, time-domain NMR with no need for isotope labeling, is gaining attention [3]. The aim of this study is to detect local mobility and orientation of chains across UHMWPE semi-crystalline network, in the solid state. The transverse relaxation time (T2) is determined from the Free Induction Decay (FID) of samples synthesized during controlled catalytic Polymerisation. The method is used to detect differences in dynamic behaviour of UHMWPE samples by mapping the crystalline/amorphous topology [3]. However, due to inhomogeneity in the magnetic field, obtaining detailed information about local chain diffusion is difficult with said experiment. Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence is designed to overcome this issue by refocusing the dephased magnetization in the transverse plane [4]. Thus, CPMG will be used for accurate measurement of the T2 distribution in UHMWPE samples at temperatures between 40-120 °C (below melting temperature). References: [1] A. Pawlak, "The Entanglements of Macromolecules and Their Influence on the Properties of Polymers," Macromolecular Chemistry and Physics, vol. 220, no. 10, p. 1900043, 2019. [2] Y. Yao, S. Jiang, and S. Rastogi, "13C Solid State NMR Characterization of Structure and Orientation Development in the Narrow and Broad Molar Mass Disentangled UHMWPE," Macromolecules, vol. 47, no. 4, pp. 1371-1382, 2014. [3] R. Bärenwald et al., "Local flips and chain motion in polyethylene crystallites: a comparison of melt-crystallized samples, reactor powders, and nanocrystals," Macromolecules, vol. 47, no. 15, pp. 5163-5173, 2014. [4] A. K. Whittaker, T. Bremner, and F. O. Zelaya, "The effect of field inhomogeneities and molecular diffusion on the NMR transverse relaxation behaviour of polymer melts," Polymer, vol. 36, no. 11, pp. 2159-2164, 1995.

• Hansen, Eddy Walther & Yao, Ye-Feng (2020). INTERFACIAL WATER IN MESOPORES BELOW FREEZING. Full text in Research Archive
• Lerum, Hans V.; Sand, Svetlana; Eriksen, Dag Øistein; Hansen, Eddy Walther; Wibetoe, Grethe & Omtvedt, Jon Petter (2018). Determination of Distribution Ratios in Liquid-liquid Extraction of Hydrometallurgical Process Solutions using ICP-MS and Radiotracer Techniques. Full text in Research Archive
• mosquera-vitas, carme; Hansen, Eddy Walther; Garcia-Santos, Hlenda; Nelson, Obregon-Neira; Ossa, Raul Ernesto Celis & Gonzalez-Murillo, Carlos Alberto [Show all 7 contributors for this article] (2017). Leaching potential of chlopyrifos in an Andisol and Entisol: adsorption-desorption and degradation studies. Geophysical Research Abstracts. ISSN 1029-7006. 19, p. 4165–4165. Full text in Research Archive Show summary

  Ecological status of tropical soils like high OC content and microbial activity plays a key role to reduce the leaching of insecticide chlorpyrifos through the soil profile and therefore into groundwater. We found that chlorpyrifos has “transitional” leaching potential (GUS values varied between 1.8 and 2.5) throughout the soil depth, which differs from the “nonleacher” classification for temperate soils as based on surface level t1/2 and Koc values from international databases. These findings provide strong evidence of the importance of estimating the transport parameters and insecticide concentrations in different soil layers, especially when the amount and type of OC content vary throughout the soil profile. We got to such conclusions after studying the soil profile structural composition of soil organic matter and the adsorption/desorption characteristics of the insecticide in two different soil profiles (Andisol and Entisol) under agriculture production using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and batch analysis methods.

• Lerum, Hans Vigeland; Bouzga, Aud Mjærum; Jørgensen, Sissel; Petersen, Dirk; Eriksen, Dag Øistein & Hansen, Eddy Walther [Show all 8 contributors for this article] (2016). Study of cadmium extraction from aqueous solutions with high chloride concentration using radiotracer and NMR. Full text in Research Archive
• Lerum, Hans Vigeland; Bouzga, Aud Mjærum; Jørgensen, Sissel; Petersen, Dirk; Eriksen, Dag Øistein & Hansen, Eddy Walther [Show all 8 contributors for this article] (2016). LIQUID-LIQUID EXTRACTION OF CADMIUM CHLORIDE COMPLEXES STUDIED BY NMR. Full text in Research Archive
• Hansen, Eddy Walther & Zhu, Han (2016). A continuous- and a discrete spin-spin relaxation rate representation of water in meat – A comparative investigation. Full text in Research Archive
• Rørvik, Per Martin; Arstad, Bjørnar; Jørgensen, Sissel; Stub, Sindre Østby; Norby, Truls & Hansen, Eddy Walther (2016). 1H-NMR and Resistance Study of Surface-Adsorbed Water in Porous YSZ. Full text in Research Archive
• Hansen, Eddy Walther & Han, Zhu (2014). SPATIAL REDISTRIBUTION OF WATER IN MEAT DURING DRIP LOSS AS PROBED BY LOW FIELD 1H-NMR. Full text in Research Archive
• Hansen, Eddy Walther (2013). Application of Solid State NMR Spectroscopy in Polymer Science. Full text in Research Archive
• Jobby, Paul; Hansen, Eddy Walther; Bouzga, Aud; Jørgensen, Sissel & Arstad, Bjørnar (2013). SIGNS OF SPATIAL HETEROGENEITIES WITHIN XLPE CABLE INSULATION PROBED BY SOLID STATE 1H-NMR. Full text in Research Archive
• Hansen, Eddy Walther (2013). Diffusion of Pore Confined Fluid Exemplified by Benzene in MOF. Full text in Research Archive
• Braovac, Susan; Kutzke, Hartmut; Jørgensen, Sissel; Bouzga, Aud Mjærum; Hansen, Eddy Walther & Arstad, Bjørnar (2012). ALUM-TREATED WOOD: CHARACTERIZATION USING INFRARED SPECTROSCOPY AND SOLID STATE NMR. Full text in Research Archive
• barreto, carlos; Hansen, Eddy Walther & Fredriksen, Siw (2012). Novl organic solvent-free purification of poly(propylene carbonate): tailoring the composition and thermal properties. Full text in Research Archive
• Hansen, Eddy Walther; Paul, Jobby; Roots, Jaan; Jørgensen, Sissel; Poltimae, T & Krumme, Andres (2012). Easy access to the amount of short chains in ethene/alfa-alkene copolymers from solid state 1H-MAS NMR. Full text in Research Archive Show summary

  Abstract Solid state 1H-MAS NMR is shown to be an attractive experimental technique for determining the comonomer content in ethene-alfa-alkene copolymers. Its advantage is associated with: a) no particular need for sample preparation, b) non-destructive, c) short overall acquisition time of the order of a few minutes. d) no need for calibration and finally e) the copolymer content in cross-linked LDPE may be determined, which is otherwise not easily accessible, as these samples are non-soluble in most liquids. References E. W. Hansen, J. Paul, S. Jørgensen, B. Arstad and A. Bouzga, IJRRAS, 2011, 6, 382–390.

• Paul, Jobby; Hansen, Eddy Walther; Roots, Jaan & Jørgensen, Sissel (2012). Thermal Oxidation of XLPE monitored by solid state 1H-NMR. Full text in Research Archive
• Hansen, Eddy Walther (2012). Application of NMR in Physical Chemistry - A Retrospective view. Full text in Research Archive
• Braovac, Susan; Kutzke, Hartmut; Jørgensen, Sissel; Bouzga, Aud Mjærum; Arstad, Bjørnar & Hansen, Eddy Walther (2011). Alum-treated wood: characterization using infrared spectroscopy and solid state 1h and 13C NMR. Full text in Research Archive Show summary

  Abstract The Oseberg find contains a large proportion of hardwoods that had been treated about 100 years ago with hot solutions of alum salts (potassium aluminum sulfate dodecahydrate, KAl(SO4)2 . 12H2O). Today, the wood is characterized by a high acidity (pH 1) and is structurally highly degraded. The observed deterioration is also active. The ‘alum treatment’ was a method of choice for the conservation of highly deteriorated waterlogged archaeological wood found from 1850 – 1950 and has since been replaced by treatment with polyethylene glycols (PEG). The alum treatment has been mainly used in Scandinavia but also in the USA, Japan and other European countries. Attempts to chemically characterize the alum-treated wood from the Oseberg find is one phase in the research currently being undertaken at the Museum of Cultural History as a part of the Alum Research Project. The ultimate aim of this project is to design conservation re-treatments which will stabilize and strengthen the wood. So far, we have focussed on non-destructive analytical techniques using ATR-FTIR and solid state NMR. Further chemical analyses are planned, using destructive techniques. Analyses using infrared spectroscopy and solid state 1H and 13C NMR were undertaken on selected alum-treated samples and compared with fresh woods as well as archaeological woods from the same find not treated with alum. The advantages of these analytical techniques lie in the fact that sample preparation is minimal prior to measurement – highly deteriorated wood can be greatly modified by standard sample preparation procedures. These techniques, when used together, give an acceptable level of qualitative structural information regarding the state of the remaining polymers. Analytical results demonstrated that all alum-treated samples are highly degraded relative to archaeological wood from the same find not treated with alum salts. The non-alum-treated archaeological wood has carbohydrates left, which are highly reduced in the alum-treated wood. 13C NMR can distinguish different lignin types, and has shown that syringyl lignin is more deteriorated than guaiacyl lignin in the most deteriorated alum-treated samples. NMR and FTIR-ATR results also show that remaining polymers in the alum-treated wood, dominated by lignins, are highly oxidized and contain carboxylic groups. This shows that the alum-treatment has caused extensive chemical changes in the wood, resulting in wood with a powdery consistency with almost no structural integrity relative to samples from Oseberg not treated with alum.

• Hansen, Eddy Walther; Gong, Xiaoliang; Chen, Qun & Zhenshu, Zhu (2011). The Distribution Properties of the Diffusivity Derived from PFG NMR Characterized by a Stretched-Exponential Response Function. Full text in Research Archive
• Hansen, Eddy Walther (2010). Chain Diffusion in Semi-Crystalline Polymers. Full text in Research Archive
• Hansen, Eddy Walther (2009). Solid State NMR - an Experimental Challenge (Principles and Applications). Full text in Research Archive
• Hansen, Eddy Walther (2009). Morphology and Chain Dynamics in PE (Spin-Diffusion and Carbon T1-relaxation). Full text in Research Archive
• Hansen, Eddy Walther (2008). Solid State NMR - An Overview. Full text in Research Archive Show summary

  Prinsippene for fastfase NMR belyst med eksempler hentet fra materialkjemien/materialfysikken

• Ukkelberg, Åsmund; Hansen, Eddy Walther; Sørland, Geir Humborstad & Widerøe, Hege C. (2008). ANAHESS, a New Second Order Inverse Laplace Transform Algorithm. Full text in Research Archive
• Hansen, Eddy Walther (2008). Spin Diffusion - Principles and Application. Full text in Research Archive
• Qun, Chen; Zhang, Lili; Shu, Jie; Hansen, Eddy Walther & Zhang, Shanmin (2007). Quantitative CP/MAS NMR methods for studying polymer structures. Full text in Research Archive
• Hansen, Eddy Walther; Ukkelberg, Åsmund; Sørland, Heir Humborstad & Widerøed, Hege C. (2007). ANAHESS, a new second order inverse Laplacetransform algorithm using analytic expressions for thegradient and the Hessian matrix, with NMR applications. Full text in Research Archive
• Hansen, Eddy Walther & Gran, Hans Christian (2006). Combined NMR Relaxation and Cryogenic NMR to Probe Pore-Architecture (Water Confined in Porous Polymer Particles). Full text in Research Archive
• Hansen, Eddy Walther; Bakken, Egil & Gran, Hans Christian (2006). Sorption energetics and diffusion of methyl salicylate in chloro-butyl rubber. Full text in Research Archive
• Hansen, Eddy Walther; Kortunov, P; Vasenkov, S; Kaerger, J; Elia, M Fe & Perez, M [Show all 17 contributors for this article] (2005). Investigation of Molecular Diffusion in FCC Catalysts. Diffusion Fundamentals. p. 458–459. Full text in Research Archive
• Hansen, Eddy Walther & Pedersen, Bjørn (2003). Årets Nobelpris i fysiologi eller medisin: Heder til NMR-spektroskopikere. Kjemi. ISSN 0023-1983. p. 14–16. Full text in Research Archive
• Hansen, Eddy Walther; Kjekshus, Arne & Odden, Jan Ove (2003). Local Arrangement of Hydrogen in Amorphous Silicon. Full text in Research Archive
• Hansen, Eddy Walther (2003). Why bother with low-field/low-resolution NMR ? Full text in Research Archive
• Hansen, Eddy Walther (2002). Probing Pore Size Distribution by Cryogenic NMR. Full text in Research Archive
• Hansen, Eddy Walther (2002). Kjernemagnetisme - hvordan utnytte den ? Full text in Research Archive Show summary

  Prinsippene for MRI og MRS presenteres og belyses med eksempler hentet bla.a fra egen forskningsaktivitet

• Hansen, Eddy Walther; Simon, Christian; Bredesen, Rune; Raeder, H & Haugsrud, R (2002). NMRT, a New Method for Direct Determination of Pore Size Distribution in Porous Membranes. Full text in Research Archive
• Hansen, Eddy Walther (2002). "NMR diffusion and relaxation measurements of organic molecules adsorbed in porous media" av Lars Gjerdåker. [Radio]. Universitetet i Bergen : Eddy W. Hansen er oppnevnt som opponent til Lars Gjerdåker's dr.scient. avhandling. Full text in Research Archive
• Hansen, Eddy Walther & Blom, Richard (2001). Rate of Diffusion of Methylaluminoxane and Toluene Through Porous Silica. Full text in Research Archive Show summary

  Metylaluminoxane (MAO) has a unique position as co-catalysts for metallocene and post-metallocene catalysts1. When heterogenising MAO/toluene on porous supports2, MAO will be distributed throughout the porous particle. How well, it will be distributed will depend on the reactivity of the surface and on the diffusion rate of MAO within the porous system. Moreover, the diffusivity may constitute the rate-limiting step of chemical reactions, and thus dictate the catalytic activity and selectivity3-5. In this work we present a simple 1H-NMR experimental approach, which enables the diffusivity within a porous material to be determined. An NMR tube was filled with deuterated toluene, and separated in two sections by a porous, cylindrical silica membrane (3 mm of length). Small amounts of non-deuterated toluene and MAO were added to one side of the membrane. The diffusion of the species through the membrane was monitored by 1H-NMR. In order to derive the diffusion coefficients, Fick's equation was solved under certain constraints and initial conditions, and the subsequent mathematical expression fitted to the observed intensity Vs time data. The analysis revealed that the diffusion coefficients of MAO and toluene within the silica membrane were slower - by a factor of 13 and 4 - compared to their bulk diffusion coefficients. Both the experimental approach and the data analysis are discussed thoroughly in the text.

• Hansen, Eddy Walther (2001). Anmeldelse av boka "Advances in Magnetic Resonance in Food Science". Kjemi. ISSN 0023-1983. p. 25–25. Full text in Research Archive Show summary

  Anmeldelse av boka "Advances in Magnetic Resonance in Food Science" av R.S.Belton, B.P.Hills and G.A.Webb (eds.), MPG Books Ltd., Bodmin, Cornwall, UK 1999, 293 sider, ISBN 0-85404-724-7

• Hansen, Eddy Walther (2000). Crosslinking of PVA and Glutaraldehyde in Water Monitored by Viscosity and PFG NMR � A comparative Study. Full text in Research Archive
• Bjørndal, Alexander Raphael Holen; Roots, Jaan & Hansen, Eddy Walther (2014). Optical Biosensors for Glucose. Universitetet i Oslo. Full text in Research Archive Show summary

  GOx was, to the authors knowledge, for the first time successfully immobilized in DGS. The intrinsic fluorescence of GOx was measured in both solution and a sol-gel derived matrix in both the presence and absence of glucose. A setup to measure the fluorescence intensity in a plate array was developed.

• Bendiksen, Bård Andre; Hansen, Eddy Walther & Walderhaug, Harald (2014). Benzenmobilitet i MOF UiO-67 karakterisert med proton lavfelt NMR-målinger -Eksperimenter og simuleringer. Universitetet i Oslo. Full text in Research Archive Show summary

  Dette arbeidet utgjør en preliminær undersøkelse av muligheten for å stu- dere sorbentmobilitet i krystallitter av det metall-organiske rammeverket UiO-67, ved å måle selvdiffusjon med et lavfelt NMR-instrument (0,5 T). UiO-67 materialet har blitt syntetisert, preparert og karakterisert for selvdif- fusjonsmålinger. Tolkningen av selvdiffusjonsmålingene har blitt kombinert med simuleringer av både sorpsjon og dynamikk. Studiet viser at det er mulig å bestemme tidsavhengigheten til utvekslingen av benzen mellom porene i krystallittene, og gassfasen mellom krystallittene. Det blir også vist at det er mulig å bestemme selvdiffusjonen til benzen inne i krystallittene som funk- sjon av temperatur. Diffusjonskoeffisientene som bestemmes er lavere enn for bulk benzen, og viser en tidsavhengighet som skyldes begrensningene porene legger på mobiliteten til benzenmolekylene inne i krystallittene. Tidsavhen- gigheten til diffusjonskoeffisienten blir brukt til å bestemme den gjennom- snittlige krystallittradien. Krystallittradien bestemt fra tidsavhengigheten i diffusjonskoeffisienten er i god overenstemmelse med den gjennomsnittlige krystallittradien som bestemmes med mikroskopi.

• Blokkdal, Espen Hagen & Hansen, Eddy Walther (2014). The Self-Diffusion Coefficient of Bulk Fluid Molecules Probed by Transverse Relaxation Measurements in an Inhomogeneous Magnetic Field. Universitetet i Oslo. Full text in Research Archive Show summary

  The possibility for performing self-diffusion measurements by Carr-Purcell-Meiboom-Gill (CPMG) experiments using the inherent magnetic field inhomogeneities as a gradient field were tested for six sample molecules, using a Maran Ultra NMR instrument with a 0.5 T permanent magnet. The method tested assumed that the magnetic field inhomogeneities could be approximated by a linear gradient, and the estimated parameter representing the magnetic field inhomogeneities in this model have been estimated to 25 μT2 m−2. The estimated diffusion coefficients were within 10-20 % of literature values, except for some samples, where convection was a problem The estimated field gradient have also been estimated from a Hahn echo experiment, and found to be consistent with the estimate from CPMG. The data obtained have also been used to probe the form of the magnetic field inhomogeneities, and have been found to be well described by a parabolic approximation. Some generalizations of the CPMG-signal was done to account for the parabolic form, which allows the CPMG-signal to be modified by introducing a correction function K, revealing the dependency of the sample height L, vertical displacement of the sample, l, and the form of the NMR tube used. Sensitivity analysis for the diffusion coefficient have been included, indicating that the diffusion coefficient may be detected as low as 10−11 m2 s−1 at the instrument used. The sensitivity of the K-function for the various parameters have also been included, revealing the sample height as the most influential parameter. The suitability for the free induction decay (FID) as an experiment for determining the transverse relaxation time have also been tested, and have been indicated to be unsuited for instruments with magnetic field inhomogeneities.

• Paul, Jobby; Hansen, Eddy Walther & Roots, Jaan (2013). Ageing of XLPE monitored by solid state1H NMR. Universitetet i Oslo. Full text in Research Archive
• Soler, Carlos Alberto Barreto; Hansen, Eddy Walther; Rychwalski, Rodney & Fredriksen, Siw (2013). Properties of poly(propylene carbonate) and nanocomposites thereof. Universitetet i Oslo. Full text in Research Archive
• Zhang, Lili; Hansen, Eddy Walther; Roots, Jaan & Chen, Qun (2009). Solid-state NMR Characterization of Crystallinity and Dynamics in Polyethylene. Universitetet i Oslo. Full text in Research Archive
• Hansen, Eddy Walther & Blom, Richard (2001). heterogenization technology. SINTEF AS. Full text in Research Archive

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