Keplerate-Type Polyoxometalates-Based Triboelectric Nanogenerator for Higher Performance via the Morphology Modulation of Blackberry Structure.

The tribe-material is the key factor affecting the performance of triboelectric nanogenerators (TENGs). Inorganic materials have higher heat resistance and stability than widely used organic materials. However, the weaker tribe-property limits the application of TENGs. Modulating surface roughness by changing particle shape and size is a simple way to increase performance for TENGs. Polyoxometalates (POMs) have unrivalled structural diversity and can self-assemble to form different nanostructures. In this study, we propose [{(NH4)42[Mo72 VIMo60 VO372(CH3COO)30 (H2O)72] ⋅ ca.300H2O ⋅ ca.CH3COONH4)}-Mo132] and [{Na8K14(VO)2[{(MoVI) (Mo5 VIO21)(H2O)3]}10{(MoVI)Mo5 VIO21(H2O)3 (SO4)}2{VIVO(H2O)20} {VIVO}10({KSO4}5)2] ⋅ 150H2O)}-Mo72V30] with blackberry structure which are cured and prepared into film by spin-coating technique, are used as positive tribe-materials for the first time in the field of TENGs. Keplerate-type POMs can form blackberry structures with higher dispersibility and flexibility, which can be used to control surface roughness by regulating the size of particles. The discovery proves that the particle size influences the surface roughness, which adjusts the output of TENGs. According to our findings, Mo132-h-TENG generates an output voltage of 29.3 V, an output charge of 8 Nc, which is 2-3 folds higher than Mo132-TENG, and a maximum power density of 6.25 mW ⋅ m-2 at 300 MΩ. Our research provides that altering the dimensional size can be an available way to raise the output of TENGs.

Polyoxometalate-Modified g-C3N4 Composites with High Work Function for Triboelectric Nanogenerators.

Designing friction materials with high electron storage capacity, high work function, low cost, and high stability is an important method to improve the output performance of a triboelectric nanogenerator (TENG). Here, we report two kinds of friction materials based on Keggin-type polyoxometalates (POMs)-modified graphite carbon nitride (g-C3N4), namely, g-C3N4@PMo12 and g-C3N4@PW12, and form TENG with commercial indium tin oxide/poly(ethylene terephthalate) (ITO/PET) electrodes. The performance test shows that the g-C3N4@PMo12 TENG device exhibits a high output voltage of about 78 V, a current of about 657 nA, and a transfer charge of about 15 nC, which is more than 3 times higher than that of unmodified TENG. This performance improvement is attributed to the fact that POM loaded on the surface of g-C3N4 can be used as a shallow electron trap to increase the electron storage capacity through electron interaction and to increase the charge density on the surface of the material by increasing the work function of the composite. This work not only broadens the choices of TENG friction materials but also offers a practical means of enhancing TENG's output performance.

Photosynthetic System Based on a Polyoxometalate-Based Dehydrated Metal-Organic Framework for Nitrogen Fixation.

In nature, biological nitrogen fixation is accomplished through the π-back-bonding mechanism of nitrogenase, which poses significant challenges for mimic artificial systems, thanks to the activation barrier associated with the N≡N bond. Consequently, this motivates us to develop efficient and reusable photocatalysts for artificial nitrogen fixation under mild conditions. We employ a charge-assisted self-assembly process toward encapsulating one polyoxometalate (POM) within a dehydrated Zr-based metal-organic framework (d-UiO-66) exhibiting nitrogen photofixation activities, thereby constructing an enzyme-mimicking photocatalyst. The dehydration of d-UiO-66 is favorable for facilitating nitrogen chemisorption and activation via the unpaired d-orbital electron at the [Zr6O6] cluster. The incorporation of POM guests enhanced the charge separation in the composites, thereby facilitating the transfer of photoexcited electrons into the π* antibonding orbital of chemisorbed N2 for efficient nitrogen fixation. Simultaneously, the catalytic efficiency of SiW9Fe3@d-UiO-66 is enhanced by 9.0 times compared to that of d-UiO-66. Moreover, SiW9Fe3@d-UiO-66 exhibits an apparent quantum efficiency (AQE) of 0.254% at 550 nm. The tactics of "working-in-tandem" achieved by POMs and d-UiO-66 are extremely vital for enhancing artificial ammonia synthesis. This study presents a paradigm for the development of an efficient artificial catalyst for nitrogen photofixation, aiming to mimic the process of biological nitrogen fixation.

Pulmonary Function Test and Obstructive Sleep Apnea Hypopnea Syndrome in Obese Adults: A Retrospective Study.

Objective: We explore risk factors related to severe obstructive sleep apnea (OSA) in obese patients, including pulmonary ventilation function, diffusion function, and impulse oscillometry (IOS) data. Methods: The medical records of 207 obese patients who were prepared to undergo bariatric surgery in a hospital from May 2020 to September 2021 were retrospectively reviewed. Polysomnography (PSG), pulmonary ventilation function, diffusion function, and IOS parameters were collected according to the ethical standards of the institutional research committee (registration number: KYLL-202008-144). Logistic regression analysis was used to analyze the related independent risk factors. Results: There were significantly statistical difference in a number of pulmonary ventilation and diffusion function parameters among the non-OSAHS group, the mild-to-moderate OSA group, and the severe OSA group. However, only airway resistance parameters R5%, R10%, R15%, R20%, R25%, and R35% increased with increasing OSA severity and were positively correlated with apnea hypopnea index (AHI). Age (P = 0.012, 1.104 (1.022, 1.192)), body mass index (P< 0.0001, 1.12 (1.057, 1.187)), gender (P = 0.003, 4.129 (1.625, 10.49)), and R25% (P = 0.007, 1.018 (1.005, 1.031)) were independent risk factors for severe OSA. In patients aged 35 to 60, RV/TLC (P = 0.029, 1.272 (1.025, 1.577)) is an independent risk factor for severe OSA. Conclusion: R25% was an independent risk factor for severe OSA in obese individuals, while RV/TLC was also an independent risk factor in those aged 35 to 60. Pulmonary function tests (PFTs), particularly IOS levels, are recommended to assess severe OSA in obese patients.

Development of an electrolysis based system to continuously recover magnesium from seawater.

The continuous resources recovery system utilizing the water electrolysis reaction was developed for recovering magnesium resources from seawater. A set of experiments for forming magnesium hydroxide from the deep-ocean water were carried out at a cathode channel separated by an ion exchange membrane. The ion concentrations of magnesium and calcium in the solution obtained from the outlet of channel were measured by ICP to evaluate the usefulness of the proposed method for the resources recovery system. Moreover, configuration and component in the precipitate formed in the proposed method were analyzed by SEM and EDS respectively. It was found that all magnesium contained in seawater can be precipitated by the proposed method. Moreover, the formation reaction of magnesium hydroxide depends on the quantity of electricity per unit volume of seawater since the production of OH- on the cathode electrode is proportional to the quantity of electricity in the water electrolysis reaction. Subsequently, the effect of deaeration from the deep-ocean water on the purity of magnesium hydroxide was investigated for forming pure magnesium hydroxide. It was found that 99% pure magnesium hydroxide can be created by applying deaeration to the deep-ocean water due to preventing formation of calcium carbonate since the carbon dioxide is removed from the seawater by deaeration.