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Artigos de revistas sobre o tema "Ultra-Low-Field NMR"

Autor: Grafiati

Publicado: 14 de março de 2023

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1

Rachineni, Kavitha, Veera Mohana Rao Kakita e Ramakrishna V. Hosur. "Ultra-high resolution in low field tabletop NMR spectrometers". RSC Adv. 7, n.º 77 (2017): 49102–4. http://dx.doi.org/10.1039/c7ra09594e.

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An approach for resolution enhancement is proposed, for data acquired on low field tabletop NMR spectrometers by employing processing-based (generalized indirect covariance) advancements in pure shift NMR.

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2

Demachi, K., S. Kawagoe, S. Ariyoshi e S. Tanaka. "Ultra-Low Field SQUID-NMR using LN2 Cooled Cu Polarizing Field coil". Journal of Physics: Conference Series 871 (julho de 2017): 012076. http://dx.doi.org/10.1088/1742-6596/871/1/012076.

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Sims, James R., Josef B. Schillig, Charles A. Swenson, David L. Gardner, Andrei N. Matlashov e Curtt N. Ammerman. "Low-Noise Pulsed Pre-Polarization Magnet Systems for Ultra-Low Field NMR". IEEE Transactions on Applied Superconductivity 20, n.º 3 (junho de 2010): 752–55. http://dx.doi.org/10.1109/tasc.2010.2040613.

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4

George Kurian, K. K., P. K. Madhu e G. Rajalakshmi. "Solid-state NMR signals at zero-to-ultra-low-field". Journal of Magnetic Resonance Open 10-11 (junho de 2022): 100049. http://dx.doi.org/10.1016/j.jmro.2022.100049.

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5

Jin, Y. R., N. Wang, S. Li, Y. Tian, Y. F. Ren, Y. L. Wu, H. Deng et al. "The Effect of Low Frequency External Field Disturbance on the SQUID Based Ultra-Low Field NMR Measurements". IEEE Transactions on Applied Superconductivity 21, n.º 3 (junho de 2011): 518–21. http://dx.doi.org/10.1109/tasc.2010.2096551.

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6

Shim, Jeong Hyun, Seong-Joo Lee, Kwon-Kyu Yu, Seong-Min Hwang e Kiwoong Kim. "Strong pulsed excitations using circularly polarized fields for ultra-low field NMR". Journal of Magnetic Resonance 239 (fevereiro de 2014): 87–90. http://dx.doi.org/10.1016/j.jmr.2013.12.007.

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7

Ganssle, Paul J., Hyun D. Shin, Scott J. Seltzer, Vikram S. Bajaj, Micah P. Ledbetter, Dmitry Budker, Svenja Knappe, John Kitching e Alexander Pines. "Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer". Angewandte Chemie 126, n.º 37 (31 de julho de 2014): 9924–28. http://dx.doi.org/10.1002/ange.201403416.

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8

Ganssle, Paul J., Hyun D. Shin, Scott J. Seltzer, Vikram S. Bajaj, Micah P. Ledbetter, Dmitry Budker, Svenja Knappe, John Kitching e Alexander Pines. "Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer". Angewandte Chemie International Edition 53, n.º 37 (31 de julho de 2014): 9766–70. http://dx.doi.org/10.1002/anie.201403416.

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9

Kiryutin, Alexey S., Ivan V. Zhukov, Fabien Ferrage, Geoffrey Bodenhausen, Alexandra V. Yurkovskaya e Konstantin L. Ivanov. "Sequential assignment of NMR spectra of peptides at natural isotopic abundance with zero- and ultra-low-field total correlation spectroscopy (ZULF-TOCSY)". Physical Chemistry Chemical Physics 23, n.º 16 (2021): 9715–20. http://dx.doi.org/10.1039/d0cp06337a.

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A novel method dubbed ZULF-TOCSY results from the combination of Zero and Ultra-Low Field (ZULF) with high-field, high-resolution NMR, leading to a generalization of the concept of total correlation spectroscopy (TOCSY).

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10

Tsunaki, S., M. Yamamoto, J. Hatta, Y. Hatsukade e S. Tanaka. "Development of contaminant detection system based on ultra-low field SQUID-NMR/MRI". Journal of Physics: Conference Series 507, n.º 4 (12 de maio de 2014): 042044. http://dx.doi.org/10.1088/1742-6596/507/4/042044.

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11

Volegov, P. L., A. N. Matlachov e R. H. Kraus. "Ultra-low field NMR measurements of liquids and gases with short relaxation times". Journal of Magnetic Resonance 183, n.º 1 (novembro de 2006): 134–41. http://dx.doi.org/10.1016/j.jmr.2006.07.021.

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12

Yanagisawa, Y., M. Hamada, K. Hashi e H. Maeda. "Review of recent developments in ultra-high field (UHF) NMR magnets in the Asia region". Superconductor Science and Technology 35, n.º 4 (7 de março de 2022): 044006. http://dx.doi.org/10.1088/1361-6668/ac5644.

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Abstract This paper reviews recent developments in ultra-high field (UHF) superconducting magnets for nuclear magnetic resonance (NMR) in the Asia regionin particular, those for high-resolution NMR magnets using high-temperature superconductor (HTS) coils. In Japan, a power supply driven-mode 1.02 GHz (24.0 T) NMR magnet using a Bi2Sr2Ca2Cu3O10-δ (Bi-2223) inner coil was developed in 2015, providing the first high-resolution NMR at a 1H NMR frequency of >1 GHz (23.5 T). In late 2017, a new project was started to develop a persistent-mode 1.3 GHz (30.5 T) NMR magnet comprising a RE(rare earth)Ba2Cu3O7-δ (REBCO) inner coil, a Bi-2223 middle coil, and a low-temperature superconductor (LTS) outer coil. The magnet employs the newly developed state-of-the-art superconducting joints between HTSs necessary for the persistent-mode operation, as well as magnet technologies providing an ultra-high magnetic field of >30.5 T with high temporal stability and spatiality homogeneity for high-resolution NMR measurement. In China, a ∼20 mm cold bored magnet comprising an LTS outer coil and no-insulation (NI) REBCO inner coils was developed and recorded a field of 32.35 T, the highest magnetic field ever achieved with an all-superconducting magnet, which can be used as a small cold-bored NMR. In Korea, a liquid helium-free 400 MHz (9.39 T) all REBCO NMR magnets using NI winding was developed, which is operational. These technologies provide future perspectives for a UHF NMR magnet with key features of persistent-mode operation, an operating field of 1.4 GHz using (32.9 T)-class magnets, and the liquid helium-free operation.

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13

YANAGIBASHI, Hideyuki, Koya ABE, Junji HIRAMA, Daisuke OYAMA e Junichi HATTA. "Development of Ultra Low Magnetic Field NMR Equipment and Non-destructive Food State Analysis". Shokubutsu Kankyo Kogaku 33, n.º 1 (2021): 12–19. http://dx.doi.org/10.2525/shita.33.12.

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14

Hatsukade, Y., T. Abe, S. Tsunaki, M. Yamamoto, H. Murata e S. Tanaka. "Application of Ultra-Low Field HTS-SQUID NMR/MRI to Contaminant Detection in Food". IEEE Transactions on Applied Superconductivity 23, n.º 3 (junho de 2013): 1602204. http://dx.doi.org/10.1109/tasc.2012.2237473.

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15

Nieminen, Jaakko O., Jens Voigt, Stefan Hartwig, Hans Jürgen Scheer, Martin Burghoff, Lutz Trahms e Risto J. Ilmoniemi. "Improved Contrast in Ultra-Low-Field MRI with Time-Dependent Bipolar Prepolarizing Fields: Theory and NMR Demonstrations". Metrology and Measurement Systems 20, n.º 3 (1 de setembro de 2013): 327–36. http://dx.doi.org/10.2478/mms-2013-0028.

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Abstract The spin-lattice (T1) relaxation rates of materials depend on the strength of the external magnetic field in which the relaxation occurs. This T1 dispersion has been suggested to offer a means to discriminate between healthy and cancerous tissue by performing magnetic resonance imaging (MRI) at low magnetic fields. In prepolarized ultra-low-field (ULF) MRI, spin precession is detected in fields of the order of 10-100 μT. To increase the signal strength, the sample is first magnetized with a relatively strong polarizing field. Typically, the polarizing field is kept constant during the polarization period. However, in ULF MRI, the polarizing-field strength can be easily varied to produce a desired time course. This paper describes how a novel variation of the polarizing-field strength and duration can optimize the contrast between two types of tissue having different T1 relaxation dispersions. In addition, NMR experiments showing that the principle works in practice are presented. The described procedure may become a key component for a promising new approach of MRI at ultra-low fields

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16

Hill-Casey, Sakho, Mohammed, Rossetto, Ahwal, Duckett, John, Richardson, Virgo e Halse. "In Situ SABRE Hyperpolarization with Earth’s Field NMR Detection". Molecules 24, n.º 22 (14 de novembro de 2019): 4126. http://dx.doi.org/10.3390/molecules24224126.

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Hyperpolarization methods, which increase the sensitivity of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI), have the potential to expand the range of applications of these powerful analytical techniques and to enable the use of smaller and cheaper devices. The signal amplification by reversible exchange (SABRE) method is of particular interest because it is relatively low-cost, straight-forward to implement, produces high-levels of renewable signal enhancement, and can be interfaced with low-cost and portable NMR detectors. In this work, we demonstrate an in situ approach to SABRE hyperpolarization that can be achieved using a simple, commercially-available Earth’s field NMR detector to provide 1H polarization levels of up to 3.3%. This corresponds to a signal enhancement over the Earth’s magnetic field by a factor of ε > 2 × 108. The key benefit of our approach is that it can be used to directly probe the polarization transfer process at the heart of the SABRE technique. In particular, we demonstrate the use of in situ hyperpolarization to observe the activation of the SABRE catalyst, the build-up of signal in the polarization transfer field (PTF), the dependence of the hyperpolarization level on the strength of the PTF, and the rate of decay of the hyperpolarization in the ultra-low-field regime.

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17

Magnelind, P. E., A. N. Matlashov, P. L. Volegov e M. A. Espy. "Ultra-Low Field NMR of ${\rm UF}_{6}$ for $^{235}{\rm U}$ Detection and Characterization". IEEE Transactions on Applied Superconductivity 19, n.º 3 (junho de 2009): 816–18. http://dx.doi.org/10.1109/tasc.2009.2019562.

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18

Savukov, Igor, Young Jin Kim e Gregory Schultz. "Detection of ultra-low field NMR signal with a commercial QuSpin single-beam atomic magnetometer". Journal of Magnetic Resonance 317 (agosto de 2020): 106780. http://dx.doi.org/10.1016/j.jmr.2020.106780.

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19

Tan, Yiqiu, Danfeng Zhou, Mengxiao Song e Jie Li. "Effective Suppression of Residual Magnetic Interference in a Conductive Shielded Room for Ultra-Low Field Nuclear Magnetic Resonance". Applied Sciences 10, n.º 11 (28 de maio de 2020): 3745. http://dx.doi.org/10.3390/app10113745.

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Residual magnetic interference induced by applied magnetic field pulses inside a conductive shielded room (SR) has been a common issue in ultra-low-field (ULF) nuclear magnetic resonance (NMR). The rapid cutoff of the applied pre-polarizing field (Bp) induces eddy currents in the walls of the SR, which produces a decaying residual magnetic interference that may cause severe image distortions and signal loss. In this study, a pair of cancellation coils (CC) and control electronics were designed for the suppression of the residual magnetic interference in a SR. Simulations show that this method was effective in suppressing the residual magnetic field (Br) after removal of the pre-polarizing magnetic field. Then, a small-scale SR was designed and the effectiveness of this cancellation scheme was experimentally verified. The test results showed a good agreement with the simulation, which indicated that the cancellation scheme was capable of reducing Br field to a much lower level. The scheme proposed in this study provides a solution for suppressing the residual magnetic field in the ULF NMR system. After decoupling the eddy–current field, the effect of the suppression may be further improved by optimization of the cancellation coil in further work.

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20

Oogane, Mikihiko, Kosuke Fujiwara, Akitake Kanno, Takafumi Nakano, Hiroshi Wagatsuma, Tadashi Arimoto, Shigemi Mizukami et al. "Sub-pT magnetic field detection by tunnel magneto-resistive sensors". Applied Physics Express 14, n.º 12 (22 de novembro de 2021): 123002. http://dx.doi.org/10.35848/1882-0786/ac3809.

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Abstract We developed tunnel magneto-resistive (TMR) sensors based on magnetic tunnel junctions (MTJs) that are able to detect a weak, sub-pT, magnetic field at a low frequency. Small detectivities of 0.94 pT/Hz1/2 at 1 Hz and 0.05 pT/Hz1/2 at 1 kHz were achieved by lowering the resistance of MTJs and enhancement of the signal using a thick CoFeSiB layer and magnetic flux concentrators. We demonstrated real-time measurement of magnetocardiography (MCG) and nuclear magnetic resonance (NMR) of protons using developed sensors. This result shows that both MCG and NMR can be measured by the same measurement system with ultra-sensitive TMR sensors.

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21

Bevilacqua, Giuseppe, Valerio Biancalana, Marco Consumi, Yordanka Dancheva, Claudio Rossi, Leonardo Stiaccini e Antonio Vigilante. "Ferromagnetic contamination of ultra-low-field-NMR sample containers. Quantification of the problem and possible solutions". Journal of Magnetism and Magnetic Materials 514 (novembro de 2020): 167220. http://dx.doi.org/10.1016/j.jmmm.2020.167220.

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22

Körber, Rainer, Jaakko O. Nieminen, Nora Höfner, Vojko Jazbinšek, Hans-Jürgen Scheer, Kiwoong Kim e Martin Burghoff. "An advanced phantom study assessing the feasibility of neuronal current imaging by ultra-low-field NMR". Journal of Magnetic Resonance 237 (dezembro de 2013): 182–90. http://dx.doi.org/10.1016/j.jmr.2013.10.011.

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23

Appelt, Stephan, F. Wolfgang Häsing, Holger Kühn, Ulrich Sieling e Bernhard Blümich. "Analysis of molecular structures by homo- and hetero-nuclear J-coupled NMR in ultra-low field". Chemical Physics Letters 440, n.º 4-6 (junho de 2007): 308–12. http://dx.doi.org/10.1016/j.cplett.2007.03.096.

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24

Ahmad, Sheikh Faisal, Young Cheol Kim, Ick Chang Choi e Hyun Deok Kim. "Recent Progress in Birdcage RF Coil Technology for MRI System". Diagnostics 10, n.º 12 (27 de novembro de 2020): 1017. http://dx.doi.org/10.3390/diagnostics10121017.

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The radio frequency (RF) coil is one of the key components of the magnetic resonance imaging (MRI) system. It has a significant impact on the performance of the nuclear magnetic resonance (NMR) detection. Among numerous practical designs of RF coils for NMR imaging, the birdcage RF coil is the most popular choice from low field to ultra-high field MRI systems. In the transmission mode, it can establish a strong and homogeneous transverse magnetic field B1 for any element at its Larmor frequency. Similarly, in the reception mode, it exhibits extremely high sensitivity for the detection of even faint NMR signals from the volume of interest. Despite the sophisticated 3D structure of the birdcage coil, the developments in the design, analysis, and implementation technologies during the past decade have rendered the development of the birdcage coils quite reasonable. This article provides a detailed review of the recent progress in the birdcage RF coil technology for the MRI system.

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25

Chighine, Kévin, Estelle Léonce, Céline Boutin, Hervé Desvaux e Patrick Berthault. "<sup>129</sup>Xe ultra-fast Z spectroscopy enables micromolar detection of biosensors on a 1 T benchtop spectrometer". Magnetic Resonance 2, n.º 1 (11 de junho de 2021): 409–20. http://dx.doi.org/10.5194/mr-2-409-2021.

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Abstract. The availability of a benchtop nuclear magnetic resonance (NMR) spectrometer, of low cost and easily transportable, can allow detection of low quantities of biosensors, provided that hyperpolarized species are used. Here we show that the micromolar threshold can easily be reached by employing laser-polarized xenon and cage molecules reversibly hosting it. Indirect detection of caged xenon is made via chemical exchange, using ultra-fast Z spectroscopy based on spatio-temporal encoding. On this non-dedicated low-field spectrometer, several ideas are proposed to improve the signal.

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26

Ganssle, Paul J., Hyun D. Shin, Scott J. Seltzer, Vikram S. Bajaj, Micah P. Ledbetter, Dmitry Budker, Svenja Knappe, John Kitching e Alexander Pines. "Titelbild: Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer (Angew. Chem. 37/2014)". Angewandte Chemie 126, n.º 37 (30 de julho de 2014): 9831. http://dx.doi.org/10.1002/ange.201406156.

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27

Linghu, Kehuan, Zhengshan Guo, Yulong Li, Tiequan Xu, Wenhao Luo, Zigeng Huang, Yirong Jin, Dongning Zheng, Furen Wang e Zizhao Gan. "The step-edge type HTS rf SQUID coupling with a LC circuit in ultra-low field NMR system". Physica C: Superconductivity and its Applications 564 (setembro de 2019): 1–5. http://dx.doi.org/10.1016/j.physc.2019.05.004.

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28

Isingizwe Nturambirwe, Jean Frederic, Willem Jacobus Perold e Umezuruike Linus Opara. "A Squid-Detected NMR Relaxation Study of Banana Fruit Ripening". Applied Engineering in Agriculture 37, n.º 2 (2021): 219–31. http://dx.doi.org/10.13031/aea.13991.

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HighlightsMeasurements of relaxation times in intact banana at micro-Tesla field was achieved.Bulk spin-spin relaxation time highly correlated with best descriptors of banana ripening.A basis for quasi-continuous distribution of spin-spin relaxation in banana was given.Abstract. Achieving fast, low-cost, and non-destructive internal quality testing techniques in the horticultural industry is a challenge. Developing techniques such as ultra-low field nuclear magnetic resonance (NMR) is a promising solution. Banana is a fast ripening fruit, which undergoes many changes in quality characteristics during ripening, and was chosen as a fit choice for extensive fruit quality study by NMR. A commercial NMR system using a superconducting quantum interference device (SQUID) as a sensor and operating at 100µT was used to measure changes that occurred in banana fruit during ripening. The longitudinal and transverse relaxation times (T1 and T2, respectively), were measured on fruit samples progressively drawn from a larger batch under storage. Physico-chemical attributes such as total soluble solids (TSS), titratable acidity (TA), pH, and color parameters were measured and used as reference measurements. Statistical analysis using cross-correlation, linear regression, analysis of variance (ANOVA), and principal components analysis (PCA) were performed to probe the relationships between various quality attributes. T1 showed high correlations with total soluble solids (R = 0.84), sugar:acid ratio (R = 0.84) and color parameters (R from 0.49 to 0.88). T2, on the other hand, was most highly correlated to pH (R = 0.76) but also had a statistically significant but negative correlation with Ri (-0.58 at p <0.05). PCA results separated the first day from the remaining days of the ripening process and the overall variation was mostly explained by color attributes (a* and h), T1, TSS, and TSS/TA. During seven days of ripening in storage, the trend of change in the peel color of banana was best described by L*, a*, h and total color difference (TCD). The index of ripening, Ri, defined based on the apparent change in peel color was highly correlated to TSS, TSS/TA, L*, a*, h, TCD, and T1. The strong similarity between the evolution of T1 and the most commonly approved characteristics of banana ripening suggest that T1 has great potential for characterizing the ripening process of banana. However, an investigation of the full metabolic profile of banana during ripening would provide an understanding of the link between NMR relaxation and ripening characteristics. A distribution of T1 relaxation time of intact banana fruit at the micro-Tesla field was successfully generated using Laplace inversion. A suitable framework of T1-domain based studies on banana ripening also applicable to other fruit was discussed; it would provide a comprehensive understanding of structural changes and water mobility that occur in ripening banana. The SQUID-detected ultra-low field NMR used here shows promise as a tool for probing the quality of intact banana fruit. Keywords: Banana quality, Laplace inversion, Relaxometry, SQUID-NMR.

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Li, Yongqiang, Peixiang Ma, Quan Tao, Hans-Joachim Krause, Siwei Yang, Guqiao Ding, Hui Dong e Xiaoming Xie. "Magnetic graphene quantum dots facilitate closed-tube one-step detection of SARS-CoV-2 with ultra-low field NMR relaxometry". Sensors and Actuators B: Chemical 337 (junho de 2021): 129786. http://dx.doi.org/10.1016/j.snb.2021.129786.

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Ganssle, Paul J., Hyun D. Shin, Scott J. Seltzer, Vikram S. Bajaj, Micah P. Ledbetter, Dmitry Budker, Svenja Knappe, John Kitching e Alexander Pines. "Cover Picture: Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer (Angew. Chem. Int. Ed. 37/2014)". Angewandte Chemie International Edition 53, n.º 37 (30 de julho de 2014): 9677. http://dx.doi.org/10.1002/anie.201406156.

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Zhang, Dan, Shohei Fukumoto, Shingo Tsunaki, Yoshimi Hatsukade e Saburo Tanaka. "Development of signal to noise ratio of HTS-rf-SQUID for ultra-low field NMR / MRI by 77K LC resonant circuit". Physics Procedia 27 (2012): 348–51. http://dx.doi.org/10.1016/j.phpro.2012.03.482.

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Zhao, Jing, Hongjie Luo e Xiao Huang. "Migration, Distribution, and Crystallization of NaCl and Na2SO4 Solutions in Three Different Media". Crystals 10, n.º 6 (30 de maio de 2020): 444. http://dx.doi.org/10.3390/cryst10060444.

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Salt damage is one of the most common and serious diseases in silicate cultural relics. In this research, low-field nuclear magnetic resonance (low-field NMR), automatic high-speed X-ray microtomography imaging, polarized light microscopy, and ultra-depth of field microscopy were applied to investigate the migration, distribution, and crystallization of NaCl and Na2SO4 on the surface of hydrophilic media, glass capillaries, and porous SiO2 materials, respectively. The results show that these two salts have different crystal growth behaviors in the same medium. NaCl grows in a granular form on the surface of hydrophilic medium and generally crystallizes outside the glass capillary tube, whereas Na2SO4 grows in a circular ring and always crystallizes inside, and some bubbles can be seen clearly in the hydrophilic medium. Meanwhile, different from NaCl, which is mainly concentrated on the upper surface of SiO2 sample, the migration of the Na2SO4 solution is distributed in the whole sample, and crystals accumulate on the interior of the sample surface. The different crystallization behaviors of salts are speculated to be related to damage conditions such as efflorescence and mural blisters in silicate cultural relics.

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Ok, S. "Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils". Grasas y Aceites 68, n.º 1 (1 de março de 2017): 173. http://dx.doi.org/10.3989/gya.0678161.

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Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively.

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Li, Dafu, Bo Tian, Kaimin Niu, Lihui Li, Lei Quan e Xuwei Zhu. "Effects of Ambient Humidity on Water Migration and Hydrate Change in Early-Age Hardened Cement Paste". Materials 15, n.º 24 (9 de dezembro de 2022): 8803. http://dx.doi.org/10.3390/ma15248803.

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Ultra-low humidity environments will lead to changes in the microstructure of C–S–H, which will reduce the mechanical properties and service life of cement-based concrete. Thus, to further explore the mechanism on the microscale, this paper studied the water migration and the changes in the hydration products in white cement that was cured for 7 days at 20 °C and at different ambient relative humidities (RHs). The migration and transformation of different types of water in cement paste were studied by low-field nuclear magnetic resonance (NMR). At the same time, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to analyze semi-quantitatively the crystal phase in the hydration products. The results showed that in the first 7 days of the curing process, the content of the different types of water and the hydration products in the cement samples were influenced by the ambient RH. The total water content of the samples will decrease with the decrease in the RH; when the RH decreases to 54% or below, the chemically bound water in the samples will increase with the decline in the RH. Additionally, when the ambient RH is lower than 54%, the grossular will gradually transform into hydrogrossular crystals with the decrease in the RH, and the hibschite with less chemically bound water will transform into katoite with more chemically bound water. In future research, the water migration and hydrate changes under different curing ages, drying processes, and coupling effects should be explored.

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Lv, Ying, Yuanming Chu, Pengcheng Zhou, Jun Mei e Jing Xie. "Effects of Different Freezing Methods on Water Distribution, Microstructure and Protein Properties of Cuttlefish during the Frozen Storage". Applied Sciences 11, n.º 15 (26 de julho de 2021): 6866. http://dx.doi.org/10.3390/app11156866.

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To study the effect of different freezing methods on the quality changes of cuttlefish during the frozen storage of cuttlefish, fresh cuttlefish was treated with six freezing methods (refrigerator direct-freezing, saline solution impregnation freezing, flat freezing, tunnel type continuous freezing, air-blast freezing and liquid nitrogen freezing) and then stored at −18 °C for 90 days. The time to pass the maximum ice crystal generation zone for the above six freezing methods in this experiment was 165.5, 67.5, 34.5, 21.8, 20.4 and 1.5 min, respectively. In this study, water retention (thawing loss rate, centrifugal loss rate, and cooking loss), pH, malondialdehyde content, TVB-N value, and sulfhydryl content were measured to evaluate the quality after thawing. Protein secondary structure was measured by attenuated total reflection infrared spectroscopy (ATR-FTIR), water migration was determined by low-field NMR, and muscle microstructure was observed by scanning electron microscopy. The results showed that among the six freezing methods, liquid nitrogen freezing took the shortest time to pass through the maximum ice crystal generation zone. And it had the highest water retention, the lowest TVB-N content, the highest sulfhydryl content and the least irregular curling of protein secondary structure after 90 days of frozen storage. However, liquid nitrogen freezing can cause cracks and breakage in cuttlefish due to cryogenic fracture caused by ultra-low temperature, which affects its sensory evaluation. Although the freezing speed of flat freezing is faster than refrigerator direct-freezing and saline solution impregnation freezing, the muscle is extruded and deformed during the freezing process, and the damage is more serious, and the frozen storage quality is the worst. The comprehensive analysis results showed that the freezing speed of air- blast freezing was faster and the quality of cuttlefish in the freezing process was better, which was the more recommended freezing method, and this study provided some theoretical basis for the selection of freezing method in the actual production of cuttlefish.

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Kirkland, Catherine M., Julia R. Krug, Frank J. Vergeldt, Lenno van den Berg, Aldrik H. Velders, Joseph D. Seymour, Sarah L. Codd, Henk Van As e Merle K. de Kreuk. "Characterizing the structure of aerobic granular sludge using ultra-high field magnetic resonance". Water Science and Technology 82, n.º 4 (27 de julho de 2020): 627–39. http://dx.doi.org/10.2166/wst.2020.341.

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Abstract Despite aerobic granular sludge wastewater treatment plants operating around the world, our understanding of internal granule structure and its relation to treatment efficiency remains limited. This can be attributed in part to the drawbacks of time-consuming, labor-intensive, and invasive microscopy protocols which effectively restrict samples sizes and may introduce artefacts. Time-domain nuclear magnetic resonance (NMR) allows non-invasive measurements which describe internal structural features of opaque, complex materials like biofilms. NMR was used to image aerobic granules collected from five full-scale wastewater treatment plants in the Netherlands and United States, as well as laboratory granules and control beads. T1 and T2 relaxation-weighted images reveal heterogeneous structures that include high- and low-density biofilm regions, water-like voids, and solid-like inclusions. Channels larger than approximately 50 μm and connected to the bulk fluid were not visible. Both cluster and ring-like structures were observed with each granule source having a characteristic structural type. These structures, and their NMR relaxation behavior, were stable over several months of storage. These observations reveal the complex structures within aerobic granules from a range of sources and highlight the need for non-invasive characterization methods like NMR to be applied in the ongoing effort to correlate structure and function.

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S. S. dos Santos, Paulo, José M. M. M. de Almeida, Isabel Pastoriza-Santos e Luís C. C. Coelho. "Advances in Plasmonic Sensing at the NIR—A Review". Sensors 21, n.º 6 (17 de março de 2021): 2111. http://dx.doi.org/10.3390/s21062111.

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Surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) are among the most common and powerful label-free refractive index-based biosensing techniques available nowadays. Focusing on LSPR sensors, their performance is highly dependent on the size, shape, and nature of the nanomaterial employed. Indeed, the tailoring of those parameters allows the development of LSPR sensors with a tunable wavelength range between the ultra-violet (UV) and near infra-red (NIR). Furthermore, dealing with LSPR along optical fiber technology, with their low attenuation coefficients at NIR, allow for the possibility to create ultra-sensitive and long-range sensing networks to be deployed in a variety of both biological and chemical sensors. This work provides a detailed review of the key science underpinning such systems as well as recent progress in the development of several LSPR-based biosensors in the NIR wavelengths, including an overview of the LSPR phenomena along recent developments in the field of nanomaterials and nanostructure development towards NIR sensing. The review ends with a consideration of key advances in terms of nanostructure characteristics for LSPR sensing and prospects for future research and advances in this field.

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Liu, Wen, Runze Chen e Sailing He. "Ultra-stable near-infrared Tm3+-doped upconversion nanoparticles for in vivo wide-field two-photon angiography with a low excitation intensity". Journal of Innovative Optical Health Sciences 12, n.º 03 (maio de 2019): 1950013. http://dx.doi.org/10.1142/s1793545819500135.

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Two-photon luminescence with near-infrared (NIR) excitation of upconversion nanoparticles (NPs) is of great importance in biological imaging due to deep penetration in high-scattering tissues, low auto-luminescence and good sectioning ability. Unfortunately, common two-photon luminescence is in visible band with an extremely high exciation power density, which limits its application. Here, we synthesized NaYF4:Yb[Formula: see text]Tm@NaYF4 upconversion NPs with strong two-photon NIR emission and a low excitation power density. Furthermore, NaYF4:Yb[Formula: see text]Tm@NaYF4@SiO2@OTMS@F127 NPs with high chemical stability were obtained by a modified multilayer coating method which was applied to upconversion NPs for the first time. In addition, it is shown that the as-prepared hydrophillic upconversion NPs have great biocompatibility and kept stable for 6 hours during in vivo whole-body imaging. The vessels with two-photon luminescence were clear even under an excitation power density as low as 25[Formula: see text]mW[Formula: see text]cm2. Vivid visualizations of capillaries and vessels in a mouse brain were also obtained with low background and high contrast. Because of cheaper instruments and safer power density, the NIR two-photon luminescence of NaYF4:Yb[Formula: see text]Tm@NaYF4 upconversion NPs could promote wider application of two-photon technology. The modified multilayer coating method could be widely used for upconversion NPs to increase the stable time of the in vivo circulation. Our work possesses a great potential for deep imaging and imaging-guided treatment in the future.

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Wang, Jian-Jun. "Research on heating technology of regenerative oxidation used low concentration CBM in small coal mine". E3S Web of Conferences 267 (2021): 02070. http://dx.doi.org/10.1051/e3sconf/202126702070.

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Aiming at the problems such as low CBM utilization rate caused by low concentration CBM with methane content less than 8% extracted from a small coal mine in Hancheng mining area, Shaanxi Province, and serious environmental pollution caused by coal-fired hot blast stove for heating, the heat storage and oxidation heating technology of ultra-low concentration gas in small coal mine was studied by combining field investigation and heat balance calculation, and ultra-low concentration gas regenerative oxidation was obtained through thermal oxidation technology scheme. This technology replaces the coal-fired hot blast stove, realizes “coal and CBM mining and sharing” in the coal mine, and constructs a virtuous cycle development of “promoting drainage by using and promoting safety by drainage”. The research shows that: the scheme improves the utilization rate of CBM in the mining area, cancels the consumption of coal combustion, and can use 2.59 million Nm3 of pure CBM every year, generating 1.95 million yuan of economic benefits. And the emissions reduction of CO2 equivalent is 36000 tons. The benefits of safety, economy and environmental protection are remarkable. This technology is especially suitable for the utilization of ultra-low concentration CBM whose concentration is less than 8%, which has practical significance to improve the CBM utilization rate and promote the realization of the goal of “zero emission”.

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Jia, Xiao-liang. "Experimental study on performance of high purity nitrogen supply system in liquefaction unit of low concentration coalbed methane". E3S Web of Conferences 267 (2021): 02076. http://dx.doi.org/10.1051/e3sconf/202126702076.

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Aiming at the problems such as low CBM utilization rate caused by low concentration CBM with methane content less than 8% extracted from a small coal mine in Hancheng mining area, Shaanxi Province, and serious environmental pollution caused by coal-fired hot blast stove for heating, the heat storage and oxidation heating technology of ultra-low concentration gas in small coal mine was studied by combining field investigation and heat balance calculation. This technology replaces the coal-fired hot blast stove, realizes “coal and CBM mining and sharing” in the coal mine, and constructs a virtuous cycle development of “promoting drainage by using and promoting safety by drainage”. The research shows that: the scheme improves the utilization rate of CBM in the mining area, cancels the consumption of coal combustion, and can use 2.59 million Nm3 of pure CBM every year, generating 1.95 million yuan of economic benefits. And the emissions reduction of CO2 equivalent is 36000 tons. The benefits of safety, economy and environmental protection are remarkable. This technology is especially suitable for the utilization of ultra-low concentration CBM whose concentration is less than 8%, which has practical significance to improve the CBM utilization rate and promote the realization of the goal of “zero emission”.

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Sinapidou, Evaggelia, Chrysanthi Pankou, Fotakis Gekas, Iosif Sistanis, Constantinos Tzantarmas, Maria Tokamani, Ioannis Mylonas et al. "Plant Yield Efficiency by Homeostasis as Selection Tool at Ultra-Low Density. A Comparative Study with Common Stability Measures in Maize". Agronomy 10, n.º 8 (16 de agosto de 2020): 1203. http://dx.doi.org/10.3390/agronomy10081203.

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The study pertains to field experimentation testing seven maize (Zea mays L.) hybrids at four densities, across five locations under normal (NIR) and low-input (LIR) regimes. The main objective was to assess the prognostic value of plant yield efficiency by homeostasis (PYEH) for breeding purposes at ultra-low plant density to predict hybrid yield potential and stability. PYEH comprises plant yield efficiency (PYE) that reflects the ability of individual plants to exploit resources, and plant yield homeostasis (PYH) that indicates the crop’s ability to evade acquired plant-to-plant variability. The same hybrids were also evaluated for stability by commonly used parametric and non-parametric statistics based on data at low (LCD) and high crop densities (HCD). Hybrid stability focused on potential yield loss due to erratic optimum density (OD). Most methods produced conflicting results regarding hybrid ranking for yield and stability especially at LCD. In contrast, PYEH consistently highlighted high-yielding and stable hybrids, potentially able to reach the attainable crop yield (ACY) inter-seasonally irrespective of crop spacing. Low density is common practice under resource-deficit conditions, so crop adaptation to crop spacing is a viable option to overcome erratic OD that constitutes a root source of crop instability in rainfed maize. The results were further supportive of breeding at ultra-low density to facilitate the identification and selection of superior genotypes, since such conditions promote phenotypic expression and differentiation, and ensure repeatability across diverse environments.

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Yu, Hongyi, Mingxing Chen e Wang Yao. "Giant magnetic field from moiré induced Berry phase in homobilayer semiconductors". National Science Review 7, n.º 1 (13 de agosto de 2019): 12–20. http://dx.doi.org/10.1093/nsr/nwz117.

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Abstract When quasiparticles move in condensed matters, the texture of their internal quantum structure as a function of position and momentum can give rise to Berry phases that have profound effects on the material’s properties. Seminal examples include the anomalous Hall and spin Hall effects from the momentum-space Berry phases in homogeneous crystals. Here, we explore a conjugate form of the electron Berry phase arising from the moiré pattern: the texture of atomic configurations in real space. In homobilayer transition metal dichalcogenides, we show that the real-space Berry phase from moiré patterns manifests as a periodic magnetic field with magnitudes of up to hundreds of Tesla. This quantity distinguishes moiré patterns from different origins, which can have an identical potential landscape, but opposite quantized magnetic flux per supercell. For low-energy carriers, the homobilayer moirés realize topological flux lattices for the quantum-spin Hall effect. An interlayer bias can continuously tune the spatial profile of the moiré magnetic field, whereas the flux per supercell is a topological quantity that can only have a quantized jump observable at a moderate bias. We also reveal the important role of the non-Abelian Berry phase in shaping the energy landscape in small moiré patterns. Our work points to new possibilities to access ultra-high magnetic fields that can be tailored to the nanoscale by electrical and mechanical controls.

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Cassará, A. M., R. Körber, I. Hilschenz, N. Höfner, J. Voigt, T. Fedele, M. Burghoff e B. Maraviglia. "Toward neuronal current spectroscopy at Ultra-Low field NMR". Biomedical Engineering / Biomedizinische Technik 57, SI-1 Track-M (4 de janeiro de 2012). http://dx.doi.org/10.1515/bmt-2012-4077.

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Tanaka, Saburo, Yuya Hirose, Junichi Hatta, Seiichiro Ariyoshi, Seiji Adachi e Keiichi Tanabe. "Ultra-Low Field High Tc SQUID NMR/MRI System with 77K Cooled Copper Flux Transformer". IEEE Transactions on Applied Superconductivity, 2015, 1. http://dx.doi.org/10.1109/tasc.2015.2512798.

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Buckenmaier, K., M. Rudolph, C. Back, T. Misztal, U. Bommerich, P. Fehling, D. Koelle et al. "SQUID-based detection of ultra-low-field multinuclear NMR of substances hyperpolarized using signal amplification by reversible exchange". Scientific Reports 7, n.º 1 (18 de outubro de 2017). http://dx.doi.org/10.1038/s41598-017-13757-7.

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46

Li, Yongqiang, Yi Xiao, Quan Tao, Mengmeng Yu, Li Zheng, Siwei Yang, Guqiao Ding, Hui Dong e Xiaoming Xie. "Selective coordination and localized polarization in graphene quantum dots: Detection of fluoride anions using ultra-low-field NMR relaxometry". Chinese Chemical Letters, maio de 2021. http://dx.doi.org/10.1016/j.cclet.2021.05.014.

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47

Wang, Anlun, Xiaoqing Zhao, Jianguang Wei, Lisha Zhao, Guangliang An, Xiaofeng Zhou, Jiangtao Li, Xuedong Shi, Ying Yang e Gen Li. "Characterization of Residual Oil Distribution in Sandstone by NMR: A Microscopic View on Oil Recovery by Miscible CO2 Flooding". Lithosphere 2022, Special 12 (24 de agosto de 2022). http://dx.doi.org/10.2113/2022/4565111.

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Abstract Miscible CO2 flooding gains rising popularity due to high displacement efficiency and potential carbon negativity. It is well documented that pore-level heterogeneity is one of the dominant mechanisms responsible for the variation in oil recovery efficiencies of miscible CO2 flooding. However, owing to a lack of understanding of miscible CO2 displacement behaviors at pore level, quantitative analysis of the mechanisms for the influence of pore-level heterogeneity on the oil recovery efficiency of miscible CO2 flooding remains problematical. Recently, NMR has been widely used to investigate microscopic residual oil distribution and pore-level displacement behaviors of various agents. Nevertheless, current NMR-based methods for determining microscopic residual oil distribution require the use of fluorinated oil, Mn2+ solution, or heavy water for eliminating the mutual interference of oil and water NMR signals. The differences in properties of reservoir fluids and additional agents could give rise to the change in displacement characteristics and consequently affect the analysis results on pore-level displacement behaviors. In this study, a method to determine microscopic residual oil distribution in sandstone during gas floodings based on NMR T2 spectrum without additional agents except reservoir fluids is proposed. Using the method, we can avoid the possible changes in the displacement characteristics caused by additional agents. Miscible CO2 flooding experiments are conducted with ultra-low and extra-low permeability cores. The T2 spectra of cores before and after flooding are measured using a 23 MHz low-field NMR instrument. Residual oil distributions in cores are quantitatively characterized using the proposed method, and then, oil recovery efficiencies from different-sized pore throats are evaluated. It is found that for both cores about 60% of the residual oil is distributed in pore throats with <0.26 μm radius. Oil residing in pore throats with >0.03 μm radius is displaceable for miscible CO2 flooding, which indicates that the thickness of the raffinate layer in the pore should be less than 0.015 μm. More than 30% of the residual oil is distributed in unswept areas, and thus, the sweep efficiency improvement is expected to effectively enhance the oil recovery of miscible CO2 flooding. The sweep efficiency is negatively affected by the pore-size heterogeneity. For the ultra-low and extra-low permeability cores, the standard deviation of pore size is 0.39 and 1.15, respectively, and correspondingly, the sweep efficiency is 84.33% and 72.84%, respectively. In the core, the oil recovery efficiencies from swept pore throats with <3 μm radius are similar and exceed 50%. Pore throats with >3 μm radius can form a preferred flow path, which will significantly reduce the oil displacement efficiency from swept pore throats with <3 μm radius. The findings of this study can help for better understanding of the microscopic CO2 miscible displacement behaviors and the mechanisms for the influence of pore-level heterogeneity on the oil recovery efficiency of miscible CO2 flooding.

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Zhang, Cheng, Jinshan Yang, Zhongbo Yan, Xiang Yuan, Yanwen Liu, Minhao Zhao, Alexey Suslov et al. "Magnetic-field-induced nonlinear transport in HfTe5". National Science Review, 26 de novembro de 2021. http://dx.doi.org/10.1093/nsr/nwab208.

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Abstract The interplay of electron correlations and topological phases gives rise to various exotic phenomena including fractionalization, excitonic instability, and axionic excitation. Recently-discovered transition-metal pentatellurides can reach the ultra-quantum limit in low magnetic fields and serve as good candidates for achieving such a combination. Here, we report evidences of density wave and metal-insulator transition in HfTe5 induced by intense magnetic fields. Using the nonlinear transport technique, we detect a distinct nonlinear conduction behavior in the longitudinal resistivity within the a-c plane, corresponding to the formation of a density wave induced by magnetic fields. In high fields, the onset of the nonlinear conduction in the Hall resistivity indicates an impurity-pinned magnetic freeze-out as the possible origin of the insulating behavior. These frozen electrons can be gradually re-activated into mobile states above a threshold electric field. These experimental evidences call for further investigations into the underlying mechanism for the bulk quantum Hall effect and field-induced phase transtions in pentatellurides.

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Wei, Danyang, Jiajie Guo, Yuqi Qiu, Shaoyu Liu, Jiangyan Mao, Yutian Liu, Zhenbing Chen, Hao Wu e Zhouping Yin. "Monitoring delicate operations of surgical robots by ultra-sensitive ionic electronic skin". National Science Review, 21 de outubro de 2022. http://dx.doi.org/10.1093/nsr/nwac227.

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Abstract Surgical robots are landmark products of high-end medical equipment, and the realization of tactile sensation is a major challenge in this important cutting-edge research field. Aiming to address this issue, we present ultra-sensitive ionic electronic skin in the form of flexible capacitive pressure sensors, which incorporate multistage bionic microstructures (MBM) in ion gels for monitoring delicate operations of surgical robots. Significantly, the ionic skin exhibits ultra-high sensitivity of 9484.3 kPa−1 (< 15 kPa), and the sensitivity remains higher than 235 kPa−1 in the wide range of 15 -155 kPa. The device has also achieved a detection limit as low as 0.12 Pa or equivalently 0.31 mg, fast response within 24 ms, and high robustness of loading/unloading for 5000 cycles without fatigue. The sensor facilitates the challenging tasks of tele-operated robotic threading, which exceeds the human tactile perception limit in handling the thread through the eye of a needle. We have also validated that ionic skin can be used in robot-assisted invasive surgery, such as incision/resection of tissues and suture of wound, to provide tactile information to surgeons to improve the operation success rates. The flexible ionic skin is capable of conforming to various shapes of robotic manipulators, thus has great promise for applications in robotic dexterous manipulation, prosthetics, and human-machine interfaces.

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Niwa, Kazuki, Kaori Hattori e Daiji Fukuda. "Few-Photon Spectral Confocal Microscopy for Cell Imaging Using Superconducting Transition Edge Sensor". Frontiers in Bioengineering and Biotechnology 9 (15 de dezembro de 2021). http://dx.doi.org/10.3389/fbioe.2021.789709.

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A superconducting transition edge sensor (TES) is an energy-dispersive single-photon detector that distinguishes the wavelength of each incident photon from visible to near-infrared (NIR) without using spectral dispersive elements. Here, we introduce an application of the TES technique for confocal laser scanning microscopy (CLSM) as proof of our concept of ultra-sensitive and wide-band wavelength range color imaging for biological samples. As a reference sample for wide-band observation, a fixed fluorescence-labeled cell sample stained with three different color dyes was observed using our TES-based CLSM method. The three different dyes were simultaneously excited by irradiating 405 and 488 nm lasers, which were coupled using an optical fiber combiner. Even when irradiated at low powers of 80 and 120 nW with the 405 and 488 nm lasers respectively, emission signals were spectrally detected by the TES and categorized into four wavelength bands: up to 500 nm (blue), from 500 to 600 nm (green), from 600 to 800 nm (red), and from 800 to 1,200 nm (NIR). Using a single scan, an RGB color image and an NIR image of the fluorescent cell sample were successfully captured with tens of photon signals in a 40 ms exposure time for each pixel. This result demonstrates that TES is a useful wide-band spectral photon detector in the field of life sciences.

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