scholarly journals A Study on Conversion Fraction and Carbonation of Pozzolan Blended Concrete through 29Si MAS NMR Analysis

2020 ◽  
Vol 10 (19) ◽  
pp. 6855
Author(s):  
Jung J. Kim ◽  
Kwang-Soo Youm ◽  
Jiho Moon
Keyword(s):  
Mechanical Properties ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
29Si Nmr ◽  
Concrete Mixtures ◽  
Carbonation Resistance ◽  
Grain Size Distributions ◽  
Water Curing ◽  
Pozzolanic Materials ◽  
Nuclear Magnetic

The object of this paper is to investigate the carbonation resistance of concretes containing different pozzolanic materials. Three concrete mixtures that included fly ash, silica fume, and nanosilica were prepared, and the mixtures were designed to have similar mechanical properties to exclude the effect of mechanical properties on the carbonation. These pozzolanic materials in concretes have different silicate contents and grain size distributions. Rapid carbonation tests were conducted to investigate the durability of pozzolan blended concretes for carbonation, and the carbonation depth was measured at one, two, four, and eight weeks after 28-day water curing. 29Si NMR (nuclear magnetic resonance) experiments were performed, and the conversion fractions for each pozzolan blended concrete were extracted. The degree of carbonation was also assessed based on the Nuclear magnetic resonance (NMR) results.

scholarly journals Permeability Calculation of Sand Conglomerate Reservoirs Based on Nuclear Magnetic Resonance (NMR)

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
You Zhou ◽  
Songtao Wu ◽  
Zhiping Li ◽  
Rukai Zhu ◽  
Shuyun Xie ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Junggar Basin ◽  
Northwest China ◽  
Free Fluid ◽  
Iteration Parameters ◽  
Nuclear Magnetic

The concept of an intermingled fractal unit (IFU) model was first proposed by Atzeni and Pia in 2008, and their model has since been successfully applied to predict thermal conductivity, electrical conductivity, and the mechanical properties of porous media materials. This paper, based on the Pia IFU model, fits the pore size distribution spectrum to quantitatively characterize the Triassic Karamay Formation conglomerate reservoirs in the Mahu region, in the Junggar Basin of Northwest China, and makes permeability predictions using the free fluid T 2 spectrum according to the nuclear magnetic resonance (NMR) experimental data. The results show that the accuracy of the IFU model is significantly higher than that of the classic Coates and SDR models for conglomerate reservoirs with complex pore structures, indicating that this is an effective method to calculate permeability based on NMR. In addition, preliminary discussions are entered into regarding the intermingled fractal expression of the Kozeny-Carman equation and the relative permeability, in order to widen the application of the IFU model in reservoir physics. The derived expressions appear complicated in form but are straightforward to calculate and apply using computer programming since their iteration parameters are definite. The findings set out in this paper provide a valuable reference for further research of the IFU model in reservoir physics.

Synthesis, characterization, crystallinity, mechanical properties, and shape memory behavior of polyurethane/hydroxyapatite nanocomposites

2020 ◽  
Vol 31 (14) ◽  
pp. 1662-1675
Author(s):  
Maryam Jalili Marand ◽  
Mostafa Rezaei ◽  
Amin Babaie ◽  
Reza Lotfi
Keyword(s):  
Mechanical Properties ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Degree Of Crystallinity ◽  
Hydroxyapatite Nanoparticles ◽  
Molecular Weights ◽  
Opening Method ◽  
Polymerization Method ◽  
Nuclear Magnetic

Herein, polycaprolactone diols with diverse molecular weights were synthesized by ring-opening method. Then, polyurethanes were synthesized through two-step pre-polymerization method by polyaddition of hydroxyl and –NCO groups. Afterward, a set of polyurethanes/hydroxyapatite nanocomposites were synthesized through solution casting as well as in situ polycondensation methods. The exact nominal molecular weights of the synthesized polycaprolactones were determined by proton nuclear magnetic resonance (hydrogen-1 nuclear magnetic resonance). Hydrogen bonding index of ester and urethane carbonyl groups (HBI(C = O)) of samples was determined through Fourier-transform infrared spectroscopy. Results showed that the incorporating of the hydroxyapatite nanoparticles has reduced HBI(C = O). X-ray diffraction patterns and differential scanning calorimetry thermographs confirmed the barrierity and nucleation performance of hydroxyapatite nanoparticles, and the variation of phase mixing degree of polyurethane’s hard and soft segments has altered the crystals size and degree of crystalline in polyurethane/hydroxyapatite nanocomposites. Field emission scanning electron microscope images showed that hydroxyapatite nanoparticles have been uniformly dispersed through in situ polymerization method. Mechanical properties were studied in the terms of HBI(C = O), hydroxyapatite nanoparticles content, and degree of crystallinity. Two different programming procedures were used to evaluate shape fixity and recovery ratios of samples at room temperature and 60°C.

Quantitative Separation of NMR Signal Amplitude of Water in Wood on the Basis of T2

2011 ◽  
Vol 704-705 ◽  
pp. 552-557
Author(s):  
Da Yan Ma ◽  
Xi Ming Wang ◽  
Ming Hui Zhang ◽  
Xue Qi Li
Keyword(s):  
Mechanical Properties ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Content ◽  
Water Distribution ◽  
Physical And Mechanical Properties ◽  
Electron Micrograph ◽  
Scanning Electron Micrograph ◽  
Scanning Electron ◽  
Nuclear Magnetic

As a kind of crude and green material, wood is essential to human life. Meanwhile, the amount of water played a vital role to almost all engineering properties of wood. Moisture affects dimensional stability, physical and mechanical properties, and susceptibility toward biological degradation. Consequently, it provides a theoretical basis for the reasonable drying model to explore the water assignment and content in timber. we present here the application of a nuclear magnetic resonance technique, which is used to quantitatively analyse water distribution in wood on the basis of T2. In this paper, we will analyse the water distribution in hardwood on the basis of T2. Refer to the scanning electron micrographs of the hardwood, we can speculate the relaxation time of the water in different cell lumens respectively. Moreover, it is even more important to calculate the organic proportion in wood by the corresponding amplitude of signal derived from the water in different cell lumens. This, compared with a scanning electron micrograph, has allowed us to produce a assumable distribution of water in wood, even the corresponding organic proportion in wood, which allows us to speculate physical and mechanical properties of wood. A mobile NMR probe has been used as a non-destructive and non-invasive tool for water content analysis on wood samples. In this paper, we will adopt NMR methods to explain. This, has opened up a way for the accurate determination of the moisture content of wood, even can be applied to the areas of food and so on. Keywords: Nuclear magnetic resonance; Water distribution in wood; T2; Scanning electron micrograph; Water content

scholarly journals Measurements of mobile and bound water by nuclear magnetic resonance correlate with mechanical properties of bone

Bone ◽  
2008 ◽  
Vol 42 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Jeffry S. Nyman ◽  
Qingwen Ni ◽  
Daniel P. Nicolella ◽  
Xiaodu Wang
Keyword(s):  
Mechanical Properties ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Bound Water ◽  
Nuclear Magnetic

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

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