Hot Pressing of Ho2O3 and Dy2O3 Based Magneto-Optical Ceramics

The paper presents results of a research on fabrication of magneto-optical ceramics based on Ho2O3 and Dy2O3 sesquioxides. The ceramics were made by hot pressing of powders prepared by self-propagating high-temperature synthesis. The methods and modes of the powder treatment developed made it possible to significantly increase the thickness of the ceramics without deterioration in optical quality in comparison with the samples obtained by vacuum sintering. The characteristics of the ceramics, such as transmission spectrum, thermal conductivity, linear thermal expansion coefficient, microhardness, elastic modulus, and crack resistance have been investigated. © 2021 The Author(s).The study was funded by the Russian Science Foundation, research project No. 18-13-00355, https://rscf.ru/en/project/18-13-00355

Improving the hyperpolarization of (31)p nuclei by synthetic design

Traditional (31)P NMR or MRI measurements suffer from low sensitivity relative to (1)H detection and consequently require longer scan times. We show here that hyperpolarization of (31)P nuclei through reversible interactions with parahydrogen can deliver substantial signal enhancements in a range of regioisomeric phosphonate esters containing a heteroaromatic motif which were synthesized in order to identify the optimum molecular scaffold for polarization transfer. A 3588-fold (31)P signal enhancement (2.34% polarization) was returned for a partially deuterated pyridyl substituted phosphonate ester. This hyperpolarization level is sufficient to allow single scan (31)P MR images of a phantom to be recorded at a 9.4 T observation field in seconds that have signal-to-noise ratios of up to 94.4 when the analyte concentration is 10 mM. In contrast, a 12 h 2048 scan measurement under standard conditions yields a signal-to-noise ratio of just 11.4. (31)P-hyperpolarized images are also reported from a 7 T preclinical scanner

Body indices and basic vital signs in Helicobacter pylori positive and negative persons

It has been hypothesized that Helicobacter pylori (Hp) infection may contribute to reduced stature, risk of hypertension or obesity. The aim was to evaluate body indices in Hp positive and negative persons. A total of 2436 subjects (4–100 years old) were tested for Hp status by 13Curea breath test. Data on height and weight were collected for 84%, and blood pressure for 80% of the study subjects. The prevalence of Hp infection was 41.6%. The odds ratio for a 10-year increase in age was 1.21 (95% CI 1.17–1.25, p-value <0.001). Statistically significant negative association of Hp positivity with body height was most pronounced in the younger age groups, while a positive association of Hp positivity with body mass index was only seen in those aged 15+ years. There was a negative effect of Hp positivity on systolic and diastolic blood pressure in subjects below 25 and a relatively strong positive effect on blood pressure in subjects over 65 years. Residual confounding by social characteristics as a possible explanation for the associations of Hp positivity with height and blood pressure cannot be excluded. Unmeasured factors related to social and family environment may cause the apparent association between Hp positivity and children’s growth and blood pressure

Strategies for the hyperpolarization of acetonitrile and related Ligands by SABRE

(Chemical Equation Presented) We report on a strategy for using SABRE (signal amplification by reversible exchange) for polarizing 1H and 13C nuclei of weakly interacting ligands which possess biologically relevant and nonaromatic motifs. We first demonstrate this via the polarization of acetonitrile, using Ir(IMes)(COD)Cl as the catalyst precursor, and confirm that the route to hyperpolarization transfer is via the J-coupling network. We extend this work to the polarization of propionitrile, benzylnitrile, benzonitrile, and trans-3-hexenedinitrile in order to assess its generality. In the 1H NMR spectrum, the signal for acetonitrile is enhanced 8-fold over its thermal counterpart when [Ir(H)2(IMes)(MeCN)3]+ is the catalyst. Upon addition of pyridine or pyridine-d5, the active catalyst changes to [Ir(H)2(IMes)- (py)2(MeCN)]+ and the resulting acetonitrile 1H signal enhancement increases to 20- and 60-fold, respectively. In 13C NMR studies, polarization transfers optimally to the quaternary 13C nucleus of MeCN while the methyl 13C is hardly polarized. Transfer to 13C is shown to occur first via the 1H - 1H coupling between the hydrides and the methyl protons and then via either the 2J or 1J couplings to the respective 13Cs, of which the 2J route is more efficient. These experimental results are rationalized through a theoretical treatment which shows excellent agreement with experiment. In the case of MeCN, longitudinal two-spin orders between pairs of 1H nuclei in the three-spin methyl group are created. Two-spin order states, between the 1H and 13C nuclei, are also created, and their existence is confirmed for Me13CN in both the 1H and 13C NMR spectra using the Only Parahydrogen Spectroscopy protocol