Fluorinated Hafnium and Zirconium Coenable the Tunable Biodegradability of Core-Multishell Heterogeneous Nanocrystals for Bioimaging.

Upconversion (UC)/downconversion (DC)-luminescent lanthanide-doped nanocrystals (LDNCs) with near-infrared (NIR, 650-1700 nm) excitation have been gaining increasing popularity in bioimaging. However, conventional NIR-excited LDNCs cannot be degraded and eliminated eventually in vivo owing to intrinsic "rigid" lattices, thus constraining clinical applications. A biodegradability-tunable heterogeneous core-shell-shell luminescent LDNC of Na3HfF7:Yb,Er@Na3ZrF7:Yb,Er@CaF2:Yb,Zr (abbreviated as HZC) was developed and modified with oxidized sodium alginate (OSA) for multimode bioimaging. The dynamic "soft" lattice-Na3Hf(Zr)F7 host and the varying Zr4+ doping content in the outmoster CaF2 shell endowed HZC with tunable degradability. Through elaborated core-shell-shell coating, Yb3+/Er3+-coupled UC red and green and DC second near-infrared (NIR-II) emissions were, respectively, enhanced by 31.23-, 150.60-, and 19.42-fold when compared with core nanocrystals. HZC generated computed tomography (CT) imaging contrast effects, thus enabling NIR-II/CT/UC trimodal imaging. OSA modification not only ensured the exemplary biocompatibility of HZC but also enabled tumor-specific diagnosis. The findings would benefit the clinical imaging translation of LDNCs.

Porous Structure of Polymer Films Optimized by Rationally Tuning Phase Separation for Passive All-Day Radiative Cooling.

Passive all-day radiative cooling (PARC) films with porous structures prepared via nonsolvent-induced phase separation (NIPS) have attracted considerable attention owing to their cost-effectiveness and wide applicability. The PARC performances of the films correlate with their porous structures. However, the porous structure formed using the NIPS process cannot be finely regulated. In this study, we prepared polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) films with porous structures optimized by rationally tuning the phase separation, which was achieved by adjusting the proportions of two good solvents with varying solubility parameters. The optimized PVDF-HFP film with a hierarchically porous structure exhibited a high solar reflectance of 97.7% and an infrared emissivity of 96.7%. The film with excellent durability achieved an average subambient cooling temperature of approximately 5.4 °C under a solar irradiance of 945 W·m-2 as well as a temperature of 11.2 °C at nighttime, thus demonstrating all-day radiative cooling. The results indicate that the proposed films present a promising platform for large-scale applications in green building cooling and achieving carbon neutrality.

Accelerated Quantum Mechanics/Molecular Mechanics Simulations via Neural Networks Incorporated with Mechanical Embedding Scheme.

A powerful tool to study the mechanism of reactions in solutions or enzymes is to perform the ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics (MD) simulations. However, the computational cost is too high due to the explicit electronic structure calculations at every time step of the simulation. A neural network (NN) method can accelerate the QM/MM-MD simulations, but it has long been a problem to accurately describe the QM/MM electrostatic coupling by NN in the electrostatic embedding (EE) scheme. In this work, we developed a new method to accelerate QM/MM calculations in the mechanic embedding (ME) scheme. The potentials and partial point charges of QM atoms are first learned in vacuo by the embedded atom neural networks (EANN) approach. MD simulations are then performed on this EANN/MM potential energy surface (PES) to obtain free energy (FE) profiles for reactions, in which the QM/MM electrostatic coupling is treated in the mechanic embedding (ME) scheme. Finally, a weighted thermodynamic perturbation (wTP) corrects the FE profiles in the ME scheme to the EE scheme. For two reactions in water and one in methanol, our simulations reproduced the B3LYP/MM free energy profiles within 0.5 kcal/mol with a speed-up of 30-60-fold. The results show that the strategy of combining EANN potential in the ME scheme with the wTP correction is efficient and reliable for chemical reaction simulations in liquid. Another advantage of our method is that the QM PES is independent of the MM subsystem, so it can be applied to various MM environments as demonstrated by an SN2 reaction studied in water and methanol individually, which used the same EANN PES. The free energy profiles are in excellent accordance with the results obtained from B3LYP/MM-MD simulations. In future, this method will be applied to the reactions of enzymes and their variants.

The impact of comprehensive blood conservation program on major complications after total aortic arch replacement.

INTRODUCTION: Patients undergoing total aortic arch replacement (TAAR) usually require blood products perioperatively. This cohort study aimed to investigate the impact of a comprehensive blood conservation program on the major complications in these patients. METHODS: Patients with traditional or comprehensive blood management intraoperatively from January 2017 to December 2018 were included. We compared the rates of major complications (cerebral vascular accident, acute kidney injury, or mortality) between the two groups after propensity score matching (PSM). The association between blood management and outcomes was assessed by logistic regression. Restricted cubic splines (RCS) were built to evaluate the impact of fresh frozen plasma (FFP) on complications. Patients were stratified by the ratio of FFP/RBC (red blood cell) to investigate the effect of the ratio on complications. RESULTS: After 1:1 PSM, 200 patients were selected. 35% (35/100) of patients suffered major complications in the traditional group, while it decreased to 22% (22/100) in the comprehensive management group (OR = 0.524, p = 0.043). Multivariable logistic regression showed that FFP was a risk factor (OR = 1.186, p = 0.014). RCS results indicated that with the increase of FFP, the risk of complications gradually increases. The cut-off value was 402 mL. Patients in the group of ratio = 0 ∼ 0.5 had a higher chance than those without transfusion (OR = 7.487, p < 0.001). CONCLUSIONS: Comprehensive blood conservation program in patients undergoing TAAR is safe and can reduce the incidence of major complications, which are associated with FFP volume and the ratio of FFP/RBC.

Feshbach resonances in D + HD(v = 1, j = 0) reaction at low collision energies.

Feshbach resonances in D + HD(v = 1, j = 0) reaction are studied by using the time-independent quantum method. The integral cross section (ICS) results present three Feshbach resonance peaks, which are different from H + HD(v = 1, j = 0) reaction dominated by only one peak. These resonances are attributed to coupling with adiabatic effective potentials of D + HD(v = 1, j = 1) reaction, and the most obvious peak is contributed by J = 1 at 83.16 cm-1 collision energy. For J = 0 and 2, the resonances are related with the same L partial wave and present a double-peak structure in total ICS. The characteristics of product angular distribution show that the resonance of J = 1 is long-lived, while the lifetimes are relatively shorter for the resonance of J = 0 and 2.

Quantum dynamics of the energy transfer for vibrationally excited HF (v = 7) colliding with D2 (v = 0): Theory assessing experiment.

It is still challenging to accurately qualify the rate coefficients for vibrationally excited molecules in experiment. In particular, for the energy transfer between HF (v = 7) and D2 (v = 0), which is a prototype for near resonant collisional transfer of vibrational excitation from one molecule to the other, the two available experimental results of rate coefficients contradict each other by a factor of nearly 20. In order to benchmark these data, in this work, the rate coefficients of vibration-vibration energy transfer processes of this system at temperatures ranging from 100 to 1500 K were calculated by employing the coupled-states approximation based on our recently developed full-dimensional ab initio intermolecular potential energy surface. The state-to-state rate coefficients were found to follow the general energy gap law. The calculated total vibration-vibration energy transfer rate coefficients decrease with the increase in the angular momentum of HF at most temperatures. The vibrational relaxation rate coefficient decreases monotonously with the temperature, and the calculated result of 8.1 × 10-11 cm3 mol-1 s-1 at room temperature is in very good agreement with the experimental value reported by Dzelzkalns and Kaufman [J. Chem. Phys. 77, 3508 (1982)].

Prediction of a Feshbach Resonance in the Below-the-Barrier Reactive Scattering of Vibrationally Excited HD with H.

Quantum reactive scattering calculations on the vibrational quenching of HD due to collisions with H were carried out employing an accurate potential energy surface. The state-to-state cross sections for the chemical reaction HD(v = 1, j = 0) + H → D + H2(v' = 0, j') at collision energies between 1 and 10 000 cm-1 are presented, and a Feshbach resonance in the low-energy regime, below the reaction barrier, is observed for the first time. The resonance is attributed to coupling with the vibrationally adiabatic potential correlating to the v = 1, j = 1 level of the HD molecule, and it is dominated by the contribution from a single partial wave. The properties of the resonance, such as its dynamic behavior, phase behavior, and lifetime, are discussed.

Many-Particle Effects in the Cyclotron Resonance of Encapsulated Monolayer Graphene.

We study the infrared cyclotron resonance of high-mobility monolayer graphene encapsulated in hexagonal boron nitride, and simultaneously observe several narrow resonance lines due to interband Landau-level transitions. By holding the magnetic field strength B constant while tuning the carrier density n, we find the transition energies show a pronounced nonmonotonic dependence on the Landau-level filling factor, ν∝n/B. This constitutes direct evidence that electron-electron interactions contribute to the Landau-level transition energies in graphene, beyond the single-particle picture. Additionally, a splitting occurs in transitions to or from the lowest Landau level, which is interpreted as a Dirac mass arising from coupling of the graphene and boron nitride lattices.

Degradation characterization and pathway analysis of chlortetracycline and oxytetracycline in a microbial fuel cell.

The wide presence of antibiotics in the environment has raised concerns about their potential impact on ecological and human health. This study was conducted to evaluate the degradation of antibiotics (chlortetracycline (CTC) and oxytetracycline (OTC)) in microbial fuel cells (MFCs) and the change of toxicity. The degradation rates of 60 mg L-1 CTC and OTC in the MFCs were 74.2% and 78%, respectively, within 7 days. The degradation ability of the two antibiotics followed the order of OTC > CTC. Toxicity test results of the zebrafish illustrated the toxicity of OTC and CTC was largely eliminated by MFC treatment. Furthermore, possible degradation pathways of CTC and OTC were speculated using LC-MS analysis. High-throughput sequencing analysis indicated that Petrimonas, Azospirillum, Dokdonella, Burkholderia and Stenotrophomonas were the predominant genera in the MFC anode biofilm. Therefore, this work is of great significance for future studies on the treatment of antibiotics in wastewater by MFCs.