Concepts in Magnetic Resonance Part A最新文献

The heteronuclear single quantum correlation (HSQC) NMR method is widely used for the structural characterization of complex mixtures. In this study, the application range of multiplicity-enhanced HSQC (HSQC-ME) spectroscopy was broadened to quantitative analysis on low-field NMR devices with standard measurement possibilities. Acquisition parameters such as number of scans and t1 increments as well as repetition time were optimized to achieve the best signal-to-ratio and resolution requiring minimum measurement time. Standardization with internal standard using correction factor and external calibration approaches for active pharmaceutical ingredients/stimulants in pharmaceutical products and dietary supplements showed average absolute bias of 5.0% and 7.7%, respectively. The HSQC-ME NMR spectroscopic method was characterized by measurement uncertainty below 4% and limits of detection below 3 mg/mL for 2-h measurement time. Semiquantitative HSQC-ME analysis of organic acids in e-cigarettes can be performed within the accuracy of 25% at low-field NMR instruments in case of overlap in 1D NMR dimension and in the presence of huge solvent signals.

The density matrix of an arbitrary pure state of a system consisting of two spin-1/2 particles is derived from the Pauli spin angular momentum operators. Mixed singlet and triplet states are then formed from linear combinations of pure states and their corresponding density matrices constructed. Singlet and triplet states are exemplified by the spin isomers parahydrogen and orthohydrogen, respectively. Partial mixing is illustrated with the example of bilinear spin–spin coupling. Various properties of the density matrices of pure and mixed states are discussed, including idempotence, factoring, and spin correlation.

An ESR spin probe technique with non-TEMPO radicals, such as nitronyl nitroxide (NN), benzonitronyl nitroxide (BzNN), and iminonitroxide (IN) radicals, was used for a porous metal-organic framework (MOF), [(ZnI₂)₃(TPT)₂] (ZnTPT; TPT = tris(4-pyridyl)-1,3,5-triazine), at room temperature. The principal values of g and hyperfine coupling (A) tensors estimated from spectral reproduction were different from those for organic matrices for some of these radicals. These results indicate that host-guest interactions occur between the ZnTPT matrix and guest radicals. Thus, when using NN, BzNN, and IN radicals as spin probes for a porous MOF, the interaction between the metal atoms or organic ligands in host materials and guest radicals should be considered. The experimental ESR spectra for the derivatives of NN or BzNN radicals were reproduced only by the rigid-limit component in the ESR time scale. However, those for the derivatives of IN radicals were approximately reproduced only by rotational diffusion around the z-axis perpendicular to the plane in the IN group. Interestingly, this reproduction was not around the y-axis of the principal axes of the g tensors, parallel to the molecular long axis, as previously observed in a few organic matrices. The IN radicals dispersed in the ZnTPT matrix are expected to be accommodated in cylindrical or pseudocylindrical nanospaces sandwiched by the pyridyl or triazine rings of TPT in ZnTPT. These findings show that the ESR spin probe technique using non-TEMPO radicals can be used to investigate the chemical and biological structures of nanosized materials.

Solid-state deuterium NMR is well suited to the study of the conformational dynamics of DNA. Deuterium quadrupole echo spectra for a particular motional model can be calculated and matched to the experimental spectrum to extract information on the DNA dynamics; however, doing so can be very time-intensive. The two-axis motion used to model the dynamics of either 2″ or 5′/5″ furanose ring deuteron is particularly complex with up to ten independent variables that can be optimized. Here, we present a program which automates both the input script generation and searches the parameter space for the best fit using a simulated annealing algorithm. The parameter, $$, provides a relative measure of goodness of fit. This method reduces the overall time to determine the best fit of a line shape to a few days, in most cases, when running on a low-power desktop PC. The automated fitting program presented here can be easily modified to generate input scripts for new models, incorporate a weighting factor to the $$ calculation to emphasize key line shape features, or fit nonsymmetrized data. This adaptable program will make simulation of solid-state deuterium spectra accessible to a broader audience.

This study was aimed to investigate the application value of magnetic resonance imaging (MRI) scanning examination in the preoperative treatment of functional glioma and to analyze the application effect of nursing intervention in the operating room in the treatment of fiber surgery. In this study, 80 patients with functional glioma were included as research objects and randomly rolled into the control group (routine nursing) and the experimental group (comfort nursing intervention in the operating room), with 40 cases in each group. All patients underwent craniocerebral MRI plain scan plus enhanced scan before surgery. The levels of the heart rate, systolic blood pressure, diastolic blood pressure, interleukin-6 (IL-6), cortisol, and anxiety before and after the intervention in the two groups were compared when patients entered the operating room (T1), when anesthesia took effect (T2), at the end of surgery (T3), when patients regained consciousness after surgery (T4), and 1 day after surgery (T5). MRI showed that the main glioma sites were located in the basal ganglia region (26.25%), followed by the central region (20.00%) and the Broca region (17.5%). The levels of IL-6 at T2, T3, and T4 in the control group were 186.45 ± 64.55 ng/L, 287.68 ± 34.59 ng/L, and 488.69 ± 81.14 ng/L, respectively, which were inferior to those at T2 (167.44 ± 15.59 ng/L), T3 (186.25 ± 52.64 ng/L), and T4 (356.57 ± 48.22 ng/L) in the test group. The SAS score of the test group after intervention (45.38 ± 2.02) was lower than that of the control group (51.03 ± 3.65) (P < 0.05). The levels of cortisol in the test group (T2 (8.89 1.23 ng/L), T3 (9.23 1.25 ng/L), and T4 (11.78 1.27 ng/L) were lower than those in the control group (T2 (11.58 ± 2.48 ng/L), T3 (12.06 ± 2.82 ng/L), and T4 (13.04 ± 11.78)). In short, preoperative MRI scanning was beneficial to detect the location of glioma in functional area. Comfort nursing in the operating room can effectively relieve the anxiety and depression of glioma patients and improve the adverse psychological conditions of the patients.

To investigate the effects of early nursing intervention on brain injury among premature infants, 100 premature infants diagnosed with brain injury were included in the research and randomly divided into the control group (50 cases) and the experimental group (50 cases). The patients in the two groups were performed with the same conventional comprehensive treatment. The patients in the control group received conventional nursing while those in the experimental group underwent early nursing intervention. During follow-up, neurodevelopment, motor behavior, the incidence rate of brain injury, and nursing satisfaction of the infants in the two groups were compared. It was demonstrated that the five neurodevelopment scores of the experimental group were all higher than those of the control group. The differences showed statistical significance (P < 0.05). The total effective rate of motor development of the experimental group reached 94%, while that of the control group amounted to 80%. Obviously, the total effective rate of motor development of the experimental group was higher than that of the control group. The difference was statistically significant (P < 0.05). The nursing satisfaction of the experimental group reached 98%, which was apparently higher than that of the control group (74%). The difference suggested statistical significance (P < 0.05). The rates of brain injury at 1 and 2 years after the birth of the experimental group were 6% and 2%, respectively. The rates of brain injury at 1 and 2 years after the birth of the control group amounted to 18% and 14%, respectively. The rates of brain injury at 1 and 2 years after the birth of the experimental group were lower than those of the control group. The difference revealed statistical significance (P < 0.05). Hence, the early nursing intervention of premature infants with brain injury could promote brain development, improve neurological function, reduce the incidence of brain injury, and achieve an ideal nursing effect.

Radiofrequency (RF) transmit field (B₁) mapping is a promising method in mitigating the B₁ inhomogeneity in various magnetic resonance imaging (MRI) applications. Although several phase- or magnitude-based B₁ mapping methods have been proposed, these methods often require complex modeling, long acquisition time, or specialized MRI sequences. A recently introduced simultaneous echo refocusing (SER) technique can be applied in the B₁ mapping method to extend the three-dimensional (3D) spatial coverage only without long data acquisition. Therefore, in this study, a multislice B₁ mapping method using composite spin echo sequences and SER techniques is proposed to obtain more accurate B₁ mapping with short data acquisition time. To evaluate the performance of the proposed B₁ mapping method, computational simulations were performed and compared with Morrell’s method, double angle method, and Yarnykh’s method. These results showed that the angle-to-noise ratio of the proposed B₁ mapping method has wider B₁ range compared to that of other B₁ mapping methods. In addition, the proposed B₁ mapping methods were compared to the multislice iterative signal intensity mapping method in both phantom and in vivo human experiments, and there was no remarkable difference between the two methods regarding the flip angle distribution in these experiments. Based on these results, this study demonstrated that the proposed B₁ mapping method is suitable for accurately measuring B₁ propagation under the condition providing reduced scan time and wider 3D coverage of B₁ mapping by applying composite RF pulse and SER techniques into the phase-sensitive method.