[en] A depolarization scheme for suppressing rigid protonated carbons in CP MASS NMR is presented. The carbon- 13 magnetization is always spin locked before the data acquisition, so that the spectrum obtained needs exactly the same phase correction as the corresponding standard CP MASS spectrum and has no any out-of-phase even for surviving protonated signals. Compared with variety of dipolar dephasing schemes, the depolarization scheme has the least intensity distortion for nonprotonated carbon signals and can be easily combined with other techniques such as TOSS

[en] The structure of lithium borovanadate (Li₂O-B₂O₃-V₂O₅) glasses was studied by ¹¹B CW-NMR technique. The fractions of BO₄ and BO₃ units were measured and analyzed. Basing on a FDB model, the structural model of lithium borovanadate glasses was proposed. It was shown by the experiment that V₂O₅ shared Li₂O with B₂O₃, and combined with B₂O₃ in the form BVO_4.5. The (N₄)_max are apporximately constant with different K. According to this experimental result, it was deduced that there is no Reedmergnerite unit in lithium borovanadate glasses. Without Li₂O, V₂O₅ and B₂O₃ could not combine directly

[en] Iterative model reconstruction (IMR) establishes image statistics and data statistics models during its iterative cycle and achieves image optimization by repeatedly correcting the differences between scan model and acquired data. IMR can significantly reduce image noise, improve image signal-to-noise ratio and contrast-to-noise ratio for head and neck CTA, and increase the diagnostic confidence of atherosclerosis and aneurysm. IMR can also increase sensitivity in detecting hyperdense artery sign in the early ischemic stroke, significantly reduce the radiation dose in CT perfusion and the iodine load of patients. In this paper, the progress of application of iterative model reconstruction technology in head and neck CT angiography was reviewed. (authors)

[en] In this paper, zirconium based metal-organic frameworks (MOFs) Zr-CAU-24 was successfully prepared by using solvothermal method, which was one kind of zirconium based MOFs. Zr-CAU-24 has nanoporous structure with BET specific surface area of 1610 m²/g. Thermogravimetric analysis (TGA) and irradiation stability test were conducted. Taking Zr-CAU-24 as adsorbent, the adsorption characteristics of Th (IV) and Ce (IV) on Zr-CAU-24 were investigated through static adsorption experiments. The effects of contact time, initial pH on Th (IV) and Ce (IV) adsorption by Zr-CAU-24 were investigated respectively, and the kinetics and thermodynamics were investigated. The results indicate that Zr-CAU-24 has good thermal stability and irradiation stability. The quasi-second-order model provides a good explanation for the adsorption process of Th (IV) and Ce (IV) on Zr-CAU-24, which is a chemical adsorption process. The active site of Zr-CAU-24 is evenly distributed, and the adsorption is a single layer adsorption. Through the study of selective adsorption of mixed metal ions on Zr-CAU-24, it is found that Zr-CAU-24 has the adsorption selectivity for Th (IV) and Ce (IV). (authors)

[en] The magnetization and the flux creep in the fluorine-doping Bi-Pb-Sr-Ca-Cu-O bulk superconductor have been experimentally studied. The experimental results exhibit some new behaviours and suggest that S dM/dlnt ∝ H^1/2 for the fields 100 Oe < H < 1000 Oe; U₀(H) ∝ exp(-H/30) for the fields below 150 Oe and U₀(H) ∝ H^-α with α = 3/2 for the fields above 150 Oe

[en] Pd/Ag alloy membrane can be used to separate and purify HT/T₂ from the offgas of TMSR. In this paper, a Pd/Ag alloy membrane with thick of 80 μm was chosen to separate H₂, which can simulate the separation of tritium. The separation effect of Pd/Ag alloy membrane in pure H₂ and H₂-Ar gas mixture was studied. The results indicate that the diffusion of atomic hydrogen through a membrane is the controlling mechanism and rate determine step of hydrogen permeation. In the condition of H₂-Ar gas mixture, the H₂ permeation flux reduces remarkably due to the influence of concentration polarization of Ar. Through the analysis of the membrane surface under SEM, the ratio of Pd in the alloy membrane increases and the grain boundary can be found, which could be inferred to the influence of H₂ permeation. (authors)

[en] Highlights: • High density copper nanowires were deposited into TNTAs by a novel electrochemical based method. • The novel core-shell Cu NWs-TNTAs composite film shows both analogue and digital resistive switching properties. • The digital resistive switching ratio is more than 40 after 1000 I–V sweeps and remains more than 20 after 10000 cycles. -- Abstract: Electrochemical nanomaterial-based resistive switching devices (memristors) have recently attracted significant research interest because of their low cost and potential applications in nonvolatile data storage and artificial neural networks. In this paper, we report an electrochemical method to produce a novel memristor based on copper nanowire-titanium dioxide nanotube arrays (TNTAs), a core-shell composite material. TNTAs are fabricated using a cheap and effective electrochemical anodization method, and high-density copper nanowires are synthesized via excess-electrodeposition with a novel peeling-off strategy. This novel memristor shows both analogue and digital resistive switching properties by controlling the electroforming process. The R_off/R_on ratio of the digital memristor remains greater than 40 during 1000 consecutive I–V sweeps. The device shows good endurance over 10⁴ pulse cycles, with an R_off/R_on ratio greater than 20. Furthermore, the data retention time can be maintained at least for 10⁴ s. The outstanding digital resistive switching performance can be attributed to the numerous parallel copper nanowire nanoelectrodes inside the film.

[en] Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago. Recent experimental and theoretical progresses have shined exciting light on this avenue. In this concise review, we will briefly introduce the basics of Rydberg atoms and their recent applications in associated areas of neutral atom quantum computation and simulation. We shall also include related discussions on quantum optics with Rydberg atomic ensembles, which are increasingly used to explore quantum computation and quantum simulation with photons. (topical review)

[en] Computed tomography (CT) perfusion (CTP) source images contain both brain perfusion and cerebrovascular information, and may allow a dynamic assessment of collaterals. The purpose of the study was to compare the image quality and the collaterals identified on multiphase CT angiography (CTA) derived from CTP datasets (hereafter called CTPA) reconstructed with iterative model reconstruction (IMR) algorithm in patients with middle cerebral artery (MCA) steno-occlusion with those of routine CTA. Consecutive patients with a unilateral MCA steno-occlusion underwent non-contrast CT (NCCT), CTP, and CTA. CTPA images were reconstructed from CTP datasets. The vascular attenuation, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of routine CTA and CTPA were measured and analyzed by Student’s t test. Subjective image quality and collaterals were scored and compared using the Wilcoxon signed-rank test. Fifty-eight patients (mean age 61.7 years, 78% males, median National Institutes of Health Stroke Scale score = 12) were included. The effective radiation dose of CTP was 1.28 mSv. The vascular attenuation, SNR, CNR, and the image quality of CTPA were considerably higher than that of CTA (all, p < 0.001). Collaterals were rated higher on CTPA compared with CTA (1.79 ± 0.64 vs. 1.22 ± 0.84, p < 0.001). Fifty-three percent of patients with poor collaterals assessed on single-phase CTA had good collaterals on CTPA. CTPA derived from CTP datasets reconstructed with IMR algorithm offers image quality comparable to routine CTA and provides time-resolved evaluation of collaterals in patients with MCA ischemic disease.

[en] Highlights: • Perchlorate was widely detected in shellfish in South China Sea. • Species-specific accumulation of perchlorate was observed. • The risk of exposure to perchlorate for residents in South China was very low. Shellfish can absorb and accumulate contaminants. The consumption of shellfish could expose humans to pollutants and increase related health risk. Perchlorate (ClO₄⁻) is a ubiquitous pollutant and could affect thyroid functions, especially for children and pregnant women. However, knowledge on the contamination of perchlorate in aquatic food such as shellfish remains limited. This study aimed to investigate the abundances of perchlorate in shellfish from South China Sea and to assess human exposure risks. A total of 178 shellfish samples from eight species were collected from offshore aquaculture waters in South China Sea. Perchlorate was detected in 99.4% of them, suggesting widespread pollution in coastal waters. Concentrations of perchlorate ranged from not detected (N.D.) to 71.5 μg kg⁻¹, with a median value of 4.33 μg kg⁻¹. Estimated daily intake (EDI) and hazard quotient (HQ) were used to assess human exposure dose and health risks, respectively. The HQ values were determined to be less than 1, indicating no significant health risks to local residents via shellfish consumption. To our knowledge, this is the first study to investigate perchlorate contamination in South China shellfish and assess potential human risks.