Theoretical Prediction and Experimental Synthesis of Zr3AC2 (A = Cd, Sb) Phases.

MAX phases have great research value and application prospects, but it is challenging to synthesize the MAX phases containing Cd and Sb for the time being. In this paper, we confirmed the existence of the 312 MAX phases of Zr3CdC2 and Zr3SbC2, both from theoretical calculations and experimental synthesis. The Zr3AC2 (A = Cd, Sb) phase was predicted by the first-principles calculations, and the two MAX phases were confirmed to meet the requests of thermal, thermodynamic, and mechanical stabilities using formation energy, phonon dispersion, and the Born-Huang criteria. Their theoretical mechanical properties were also systematically investigated. It was found that the elastic moduli of Zr3CdC2 and Zr3SbC2 were 162.8 GPa and 164.3 GPa, respectively. Then, differences in the mechanical properties of Zr3AC2 (A = Cd, In, Sn, and Sb) were explained using bond layouts and charge transfers. The low theoretical Vickers hardness of the Zr3CdC2 (5.4 GPa) and Zr3SbC2 (4.3 GPa) phases exhibited excellent machinability. Subsequently, through spark plasma sintering, composites containing Zr3CdC2 and Zr3SbC2 phases were successfully synthesized at the temperatures of 850 °C and 1300 °C, respectively. The optimal molar ratio of Zr:Cd/Sb:C was determined as 3:1.5:1.5. SEM and the EDS results analysis confirmed the typical layered microstructure of Zr3CdC2 and Zr3SbC2 grains.

Built-in Electric Field Promotes Interfacial Adsorption and Activation of CO2 for C1 Products over a Wide Potential Window.

The unsatisfactory adsorption and activation of CO2 suppress electrochemical reduction over a wide potential window. Herein, the built-in electric field (BIEF) at the CeO2/In2O3 n-n heterostructure realizes the C1 (CO and HCOO-) selectivity over 90.0% in a broad range of potentials from -0.7 to -1.1 V with a maximum value of 98.7 ± 0.3% at -0.8 V. In addition, the C1 current density (-1.1 V) of the CeO2/In2O3 heterostructure with a BIEF is about 2.0- and 3.2-fold that of In2O3 and a physically mixed sample, respectively. The experimental and theoretical calculation results indicate that the introduction of CeO2 triggered the charge redistribution and formed the BIEF at the interfaces, which enhanced the interfacial adsorption and activation of CO2 at low overpotentials. Furthermore, the promoting effect was also extended to CeO2/In2S3. This work gives a deep understanding of BIEF engineering for highly efficient CO2 electroreduction over a wide potential window.

Metal-Driven Autoantifriction Function of Artificial Hip Joint.

The service life of an artificial hip joint is limited to 10-15 years, which is not ideal for young patients. To extend the lifespan of these prostheses, the coefficient of friction and wear resistance of metallic femoral heads must be improved. In this study, a Cu-doped titanium nitride (TiNX -Cu) film with "autoantifriction" properties is deposited on a CoCrMo alloy via magnetron sputtering. When delivered in a protein-containing lubricating medium, the Cu in TiNX -Cu quickly and consistently binds to the protein molecules in the microenvironment, resulting in the formation of a stable protein layer. The proteins adsorbed on the TiNX -Cu surface decompose into hydrocarbon fragments owing to the shear stress between the Al2 O3 /TiNX -Cu tribopair. The synergistic effect of the catalysis of Cu and shear stress between the Al2 O3 /TiNX -Cu tribopair transforms these fragments into graphite-like carbon tribofilms with an antifriction property. These tribofilms can simultaneously reduce the friction coefficient of the Al2 O3 /TiNX -Cu tribopair and enhance the wear resistance of the TiNX -Cu film. Based on these findings, it is believed that the autoantifriction film can drive the generation of antifriction tribofilms for lubricating and increasing the wear resistance of prosthetic devices, thereby prolonging their lifespan.

Enhanced lithium polysulfide adsorption on an iron-oxide-modified separator for Li-S batteries.

Lithium-sulfur (Li-S) batteries are candidates for next-generation energy storage systems because of their low cost, high theoretical specific capacity and safety. However, the serious lithium polysulfide (LiPS) shuttle effect leads to a loss of reactive active substances and reduction of coulombic efficiency. In the current work, iron oxide (IO-700)-prepared by calcining a mixture of carbon spheres and ferric nitrate under an air atmosphere at 700 °C-was designed as a separator modifier to effectively adsorb LiPSs and accelerate the kinetics of the transformation of the intermediates, thereby inhibiting the shuttle effect. Li-S batteries including IO-700 showed long-term stability for 1000 cycles at 1C, with a capacity decay rate per cycle of only 0.0487%. A theoretical calculation indicated that, due to strongly polar active sites, Fe2O3 adsorbed LiPSs effectively to suppress the shuttle effect. This work has highlighted the importance for Li-S batteries of strongly polar active sites for anchoring LiPSs to inhibit the shuttle effect.

Potential of metagenomic next-generation sequencing in detecting infections of ICU patients.

BACKGROUND: Due to the limitations of traditional microbiological detection techniques in evaluating complicated infections in ICU patients, it is necessary to explore novel and effective methods to improve the clinical detection of ICU patients' infections. OBJECTIVE: This study aimed to evaluate the efficiency and specificity of mNGS in screening pathogens in the blood, deep phlegm, urine, and other sample types of ICU patients exploring an effective method for infection detection. METHODS: A total of 56 ICU patients with 131 samples were included in this study. The sample types included blood, deep phlegm, urine, drainage, anal swabs, and other types. Samples were analyzed by both conventional detection method and mNGS tests. The diagnosis efficiency and consistency of the two methods were compared. The distribution of the identified pathogens was analyzed. Moreover, the clinical features of patients with mNGS-positive or mNGS-negative results were compared. RESULTS: The positive rate of mNGS was 81.7% (107/131) including 3.1% (4/131) weakly positive, while the positive rate of traditional detection was only 30.5%, including 29 strong positive results and 11 weak positive results. Additionally, there were 41 patients chose to adjust anti-infection strategies according to the results of mNGS, which significantly saved treatment costs. The mNGS-positive patients showed a shorter ICU hospitalization and higher intention to adjust anti-infection strategies than the mNGS-negative patients. CONCLUSION: mNGS is of great potential for the pathogen detection of ICU patients, and has a higher detection rate than traditional detection methods. Further clinical application investigations can be carried out to expand the application of mNGS.

[Study of hospitalization risk indicators for intensive care unit patients evaluated by intelligent calculation method].

OBJECTIVE: To explore the characteristics of the changes in risk score for intensive care unit (ICU) patients during hospitalization by the intelligent calculation method, and to provide evidence for the risk prevention. METHODS: In this retrospective study, ICU patients of the Fifth Central Hospital in Tianjin from November 3, 2021 to March 28, 2022 were enrolled and divided into ≥ 14 days group, 10-13 days group, 7-9 days group, and 3-6 days group according to the ICU length of stay. Risk scores assessed by the intelligent calculation method of the ICU patients were collected, including nutritional risk screening 2002 (NRS 2002), Caprini score and Padua score. NRS 2002 score for all patients, Caprini score for surgical patients and Padua score for internal medicine patients were selected. Trends in change of each score were compared between patients admitted to ICU 1, 3, 7 (if necessary), 10 (if necessary), and 14 days (if necessary). RESULTS: A total of 138 patients were involved, including 79 males and 59 females, with an average age of (61.71±18.86) years and an average hospital stay of [6.00 (4.00, 9.25)] days. (1) in the group with ICU length of stay ≥ 14 days (21 cases): there was no significant change in the NRS 2002 scores of the patients within 10 days, but the NRS 2002 score was significantly decreased in 14 days as compared with 1 day [3.00 (2.50, 3.50) vs. 4.00 (3.00, 5.00), P < 0.05]; both Caprini and Padua score were increased with prolonged hospital stay and compared with 1 day, the scores at the other time points were significantly increased, especially at 14 days [Caprini score: 5.00 (3.25,7.00) vs. 2.50 (1.25, 5.50), Padua score: 6.00 (6.00, 7.00) vs. 3.00 (1.00, 3.00), both P < 0.05]. (2) in the group with ICU length of stay from 10-13 days (15 cases): with the prolonged hospital stay, there was no significant change in NRS 2002 score, but both Caprini and Padua score were increased at 3, 7, 10 days, especially at 10 days [Caprini score: 3.00 (2.00, 4.75) vs. 2.00 (0.25, 2.75), Padua score: 5.00 (3.50, 6.00) vs. 2.00 (0.50, 4.00), both P < 0.05]. (3) in the group with ICU length of stay from 7-9 days (23 cases): compared with 1 day, the NRS 2002 score at 3 days and7 days were decreased, but the Caprini and Padua score were increased, especially at 7 days [NRS 2002 score: 2.00 (1.00, 4.00) vs. 2.00 (2.00, 4.00), Caprini score: 3.00 (2.00, 5.50) vs. 2.00 (0.25, 3.00), Padua score: 5.00 (4.00, 6.00) vs. 2.00 (0,2.00),all P < 0.05]. (4) in the group with ICU length of stay from 3-6 days (79 cases): compared with 1 day, the NRS 2002 score at 3 days was decreased [NRS 2002 score: 2.00 (1.00, 3.00) vs. 2.00 (1.00, 3.00), P < 0.05], Caprini and Padua score were significantly increased [Caprini score: 3.00 (2.00, 4.00) vs. 2.00 (1.00, 3.00), Padua score: 5.00 (4.00, 5.00) vs. 2.00 (1.00, 3.00), both P < 0.05]. CONCLUSIONS: Based on dynamic assessment of intelligent calculation methods, the risk of thrombosis in ICU patients increased with hospital length of stay, and the nutritional risk was generally flat or reducing in different hospitalization periods.

Ultra-Fast Thermal Shock Evaluation of Ti2AlC Ceramic.

In this work, the rapid thermal shock behavior of Ti2AlC ceramics was studied using induction heating. The present evaluation method possesses the merits of very rapid heating within tens of seconds and fast quenching in water of less than 0.1 s, removing the shortcomings of traditional thermal shock. For comparison, the samples were also quenched in the air to investigate the thermal shock mechanisms. The results showed that the abnormal shock occurred in the samples when quenching in water, ascribed to the formed oxide layer on the surface of Ti2AlC ceramic inhibited the water penetration into the substrate. The quenched Ti2AlC samples still had a high residual flexural strength above 167 MPa up to 1150 °C, exhibiting promising applications in the high-temperature fields.

Quasi-solid-state Zn-air batteries with an atomically dispersed cobalt electrocatalyst and organohydrogel electrolyte.

Quasi-solid-state Zn-air batteries are usually limited to relatively low-rate ability (<10 mA cm-2), which is caused in part by sluggish oxygen electrocatalysis and unstable electrochemical interfaces. Here we present a high-rate and robust quasi-solid-state Zn-air battery enabled by atomically dispersed cobalt sites anchored on wrinkled nitrogen doped graphene as the air cathode and a polyacrylamide organohydrogel electrolyte with its hydrogen-bond network modified by the addition of dimethyl sulfoxide. This design enables a cycling current density of 100 mA cm-2 over 50 h at 25 °C. A low-temperature cycling stability of over 300 h (at 0.5 mA cm-2) with over 90% capacity retention at -60 °C and a broad temperature adaptability (-60 to 60 °C) are also demonstrated.

The effects of prey lipid on female mating and reproduction of a wolf spider.

As predators, the macronutrients spiders extract from their prey play important roles in their mating and reproduction. Previous studies of macronutrients on spider mating and reproduction focus on protein, the potential impact of prey lipid content on spider mating and reproduction remains largely unexplored. Here, we tested the influence of prey varying in lipid content on female mating, sexual cannibalism, reproduction, and offspring fitness in the wolf spider Pardosa pseudoannulata. We acquired 2 groups of fruit fly Drosophila melanogaster that differed significantly in lipid but not protein content by supplementing cultural media with a high or low dose of sucrose on which the fruit flies were reared (HL: high lipid and LL: low lipid). Subadult (i.e., 1 molt before adult) female spiders that fed HL flies matured with significantly higher lipid content than those fed LL flies. We found that the mated females fed with HL flies significantly shortened pre-oviposition time and resulted in a significantly higher fecundity. However, there was no significant difference in female spiders varying in lipid content on other behaviors and traits, including the latency to courtship, courtship duration, mating, copulation duration, sexual cannibalism, offspring body size, and survival. Hence, our results suggest that the lipid content of prey may be a limiting factor for female reproduction, but not for other behavioral traits in the wolf spiders P. pseudoannulata.

First principles investigation of electron correlation and Lifshitz transition within iron polynitrides.

Metal poly-nitrogen compounds are gaining great interests as potential high energy density materials. Several iron polynitrides have been recently synthesized and investigated under high pressure (2018Nature Communications92756). In this work the electron correlations within these iron poly-nitrogen compounds were self-consistently determined, benchmarked with those obtained from linear response approach. Along with the increase of the concentration of nitrogen, the Coulomb interaction strengths show a monotonic decrease, where FeN and FeN2are antiferromagnetic and the others are ferromagnetic. Then the electron correlation is studied along with the pressure, where the electrons are more delocalized as pressure becomes higher. One electronic topological transition was found for FeN2, owing to a breaking of symmetry of spin and a transition of magnetism induced by a structural change. The band structure, densities of states, Fermi surface and absorption spectra were calculated and discussed.

[Effect of different fluid resuscitation strategies on renal function in patients with septic shock induced acute kidney injury].

OBJECTIVE: To compare the therapeutic effect of fluid resuscitation strategy guided by pulse-indicated continuous cardiac output (PiCCO) monitoring and early goal-directed therapy (EGDT) on renal function of acute kidney injury (AKI) patients caused by septic shock. METHODS: Septic shock patients with AKI admitted to the intensive care unit (ICU) of Tianjin Fifth Central Hospital and Teda International Cardiovascular Hospital from March 2017 to February 2020 were enrolled. All patients were given fluid resuscitation. Patients were divided into PiCCO-guided fluid resuscitation group [PiCCO group, intrathoracic blood volume index (ITBVI) was maintained between 850-1 000 mL/m2] and EGDT-guided fluid resuscitation group [EGDT group, central venous pressure (CVP) was maintained between 8-12 mmHg (1 mmHg = 0.133 kPa) or CVP ≤ 15 mmHg when patients received mechanical ventilation (MV)] according to both the patient's condition and the informed consent of the patient's family. The changes of heart rate (HR), mean arterial pressure (MAP), CVP, blood lactic acid (Lac), fluid balance, urine volume and serum creatinine (SCr) at 6, 24, and 48 hours after fluid resuscitation in the two groups were observed, and the renal replacement therapy (RRT), duration of MV, length of ICU stay and 28-day mortality between the two group were compared. RESULTS: (1) A total of 94 patients were enrolled, including 51 in the EGDT group and 43 in the PiCCO group. There was no significant difference in gender, age, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score, procalcitonin (PCT), HR, MAP, CVP, Lac or SCr at ICU admission between the two groups. (2) The parameters of hemodynamics, fluid balance, urine volume and SCr were improved with the time of resuscitation in the two groups, and there was no significant difference in HR, MAP or Lac between the two groups. Compared with the EGDT group, the CVP decreased significantly at 24 hours and 48 hours after fluid resuscitation in the PiCCO group (mmHg: 9.1±0.9 vs. 12.0±1.3 at 24 hours, 8.0±1.0 vs. 10.2±1.3 at 48 hours), the fluid balance significantly decreased (mL: 2 929.8±936.3 vs. 3 898.4±923.5 at 24 hours, 3 143.5±1 325.4 vs. 4 843.8±1 326.7 at 48 hours), and the condition of urine volume and SCr were better in the PiCCO group [urine volume (mL×kg-1×h-1): 1.02±0.21 vs. 0.79±0.14 at 24 hours, 1.28±0.18 vs. 0.94±0.22 at 48 hours; SCr (µmol/L): 145.7±37.6 vs. 164.3±46.4 at 24 hours, 128.4±33.6 vs. 143.5±37.7 at 48 hours), with significant differences (all P < 0.05). (3) Compared with the EGDT group, the rate of RRT in the PiCCO group was lower [11.6% (5/43) vs. 17.6% (9/51)], the duration of MV and the length of ICU stay were shorter [duration of MV (days): 4.64±1.31 vs. 6.50±2.19, length of ICU stay (days): 10.35±3.50 vs. 14.50±5.78), with significant differences (all P < 0.05). There was no significant difference in the 28-day mortality between the PiCCO group and EGDT group [14.0% (6/43) vs. 15.7% (8/51), P > 0.05]. CONCLUSIONS: Fluid resuscitation strategy guided by PiCCO in septic shock patients with AKI can reduce the amount of fluid load, improve renal function, shorten the MV duration and length of ICU stay, and shows clinical significance.

[Change and significance of coagulation function and von Willebrand factor antigen level in HELLP syndrome].

OBJECTIVE: To investigate the changes and clinical significance of blood coagulation function and von Willebrand factor antigen (vWF:Ag) in patients with HELLP syndrome (hemolysis, elevated liver function, low platelet count). METHODS: The clotting data of patients with severe preeclampsia and HELLP syndrome (observation group) admitted to the department of critical care medicine of the Fifth Center Hospital in Tianjin from May 2015 to December 2019 were retrospectively analyzed, and normal late pregnancy women with the same period were enrolled as the control group. The coagulation indexes such as prothrombin time (PT), activated partial thrombin time (APTT), antithrombin (AT), fibrinogen (Fib), D-dimer and plasma vWF:Ag level were compared between the two groups, and among patients with HELLP syndrome with different disease degree. RESULTS: (1) Sixty-five patients with HELLP syndrome and 65 normal pregnant women with third trimester were included. Both groups were women of childbearing age, and there were no significant difference in the baseline data. (2) The levels of Fib, D-dimer in both groups increased, but they were significantly higher in the observation group than those in the control group [Fib (g/L): 4.94 (4.76, 5.85) vs. 3.58 (2.97, 4.14), D-dimer (mg/L): 3.34 (2.55, 4.32) vs. 1.72 (1.29, 2.08), both P < 0.05], the AT was obviously reduced [62.00 (49.00, 73.00)% vs. 97.50 (90.75, 107.00)%, P < 0.01], and both PT and APTT were in the normal reference range in the two groups. In addition, the plasma vWF:Ag level in the observation group was significantly higher than that in the control group [516.50 (467.20, 563.00)% vs. 246.45 (189.95, 274.10)%, P < 0.01]. (3) According to thrombocytopenia, among the 65 patients with HELLP syndrome, 26 cases were mild [platelet count (PLT) > 100×109/L], 22 cases were moderate [PLT (50-100)×109/L], and 17 cases were severe (PLT < 50×109/L). With the aggravation of the disease, the D-dimer, Fib, vWF:Ag levels in the mild, moderate, severe patients significantly increased, while the AT level significantly decreased, and there was statistically significant difference between the two groups [D-dimer (mg/L): 2.63 (2.60, 2.73), 3.15 (2.55, 3.73), 3.84 (3.52, 4.23); Fib (g/L): 4.23 (4.06, 4.47), 4.72 (4.34, 5.04), 5.43 (5.14, 5.76); vWF:Ag: 465.20 (437.20, 495.40)%, 500.10 (472.40, 534.50)%, 543.50 (521.30, 563.00)%; AT: 67.50 (61.60, 78.00)%, 63.70 (53.30, 70.40)%, 54.40 (44.00, 61.20)%; all P < 0.05]. CONCLUSIONS: Patients with HELLP syndrome may show hypercoagulability and excessive expression of peripheral blood vWF:Ag level, which can induce platelet aggregation, leading to thrombocytopenia and thrombotic microangiopathy, and the clinicians should pay attention to that.

Accelerating charge transfer to enhance H2 evolution of defect-rich CoFe2O4 by constructing a Schottky junction.

We demonstrate a charge transfer boosted hydrogen (H2) evolution of transition metal oxides via a Schottky junction. The FeNi and metallic defect-rich CoFe2O4 (DCF) as well as semiconducting nitrogen-doped carbon (NC), named as FeNi/DCF/NC, possessed only 6.5% charge transfer resistance of DCF. Theoretical calculations indicate that the enhanced electron movement happened from FeNi/DCF to NC. The H2 evolution activity of FeNi/DCF/NC showed 5.8-fold improvement compared to that of DCF at the overpotential of 400 mV in 1.0 M KOH. This work provides an effective way to enhance the electrocatalytic activity of oxides for the H2 evolution reaction and related reactions.

Electron correlation effect versus spin-orbit coupling for tungsten and impurities.

The electron correlation and spin-orbit coupling (SOC) effects are investigated for body-centered-cubic tungsten and intrinsic & irradiative impurities using first principles calculations based upon the density functional theory. It is found that the electron correlation between the localized 5d electrons and the SOC effect are significant in modifying the band structures and the formation energies of defects. For the latter one, the involving of electron correlation always makes the defects stabler than the Perdew-Burke-Ernzerhof results, while the SOC contributes diversely for different defects. Moreover, the migration barrier of single tungsten vacancy moving in ⟨111⟩ direction is explored, where the inclusion of electron correlations remarkably decreases the migration barrier, while the influence of SOC is almost negligible. This study can help to validate the previous studies on irradiative defects in tungsten and improve the further investigations.

Electronic, magnetic and optical properties of transition-metal and hydroxides doped monolayer g-C3N4: a first principles investigation.

The graphitic carbon nitride (g-C3N4) is a promising layered two-dimension material with an opened bandgap. It is of interest to explore the tunability of the bandgap together with the magnetism by doping transition metal atoms. In this work, we investigated the transition metals (Mn, Fe, Co, Ni) and their hydroxides doped g-C3N4 monolayers. The electron correlations between the 3d electrons of the doped transition metal atoms are self-consistently calculated and analyzed based on the density functional theory. The magnetism, electronic band structures and optical properties are systematically investigated. It reveals that the transition metal doped g-C3N4 is ferromagnetic (FM) state at small doping concentration, where the two spins show different bandgaps. When the doping is high enough, it turns to metallic antiferromagnetic (AFM) state except that Mn doped g-C3N4 is metallic FM state. On another hand, the system shows variable absorption spectra at different doping level. When the vacancy sites are fully occupied, a large absorption peak appears around 1.5 eV suitable for visible light. Moreover, within the transition metal hydroxides doped g-C3N4, the global ground state shows as AFM, and the absorption spectra within low energy range is distinct due to the presence of hydroxyl group. Therefore, doping with transition metal atoms and hydroxides can effectively tune the bandgap, magnetism and optical properties of g-C3N4 so as to promote its applications.

[Comparison of pulmonary circulation hemodynamics and respiratory mechanics induced by drowning with equal volume of freshwater and seawater in sheep: a randomized controlled study].

OBJECTIVE: To compare the effects of freshwater and seawater drowning on sheep's pulmonary circulation hemodynamics and respiratory mechanics. METHODS: According to the random number table method, healthy crossbred sheep were divided into freshwater drowning group (n = 12) and seawater drowning group (n = 12). 30 mL/kg of freshwater or seawater was infused respectively through trachea for approximately 5 minutes. Before the drowning, immediately after drowning, and 30, 60, 120 minutes after drowning, the systemic circulation hemodynamic parameters [heart rate (HR), mean arterial pressure (MAP), cardiac output (CO)] were monitored by pulse indicator continuous cardiac output (PiCCO); the respiratory parameters were obtained through the ventilator, including tidal volume (VT), lung compliance (Cdyn), oxygenation index (PaO2/FiO2), peak airway pressure (Ppeak)]; PiCCO and the right heart floating catheter (Swan-Ganz catheter) was used to measure pulmonary hemodynamic parameters [pulmonary systolic pressure (PAS), pulmonary diastolic pressure (PAD), pulmonary artery wedge pressure (PAWP), and extravascular lung water (EVLW)]. The animals were sacrificed at the end of the experiment, and the amount of residual water in the respiratory tract was measured; the pathological changes in the lung tissue were observed by hematoxylin-eosin (HE) staining. RESULTS: (1) Systemic circulation hemodynamics: compared with the values before drowning, HR, MAP, and CO at the time of immediately after drowning in both freshwater and seawater were significantly increased and peaked. In addition, all indicators in the freshwater drowning group were significantly higher than those in the seawater drowning group [HR (bpm): 170.75±1.87 vs. 168.67±2.27, MAP (mmHg, 1 mmHg = 0.133 kPa): 172.92±1.62 vs. 159.42±3.18, CO (L/min): 13.27±0.71 vs. 10.33±0.73, all P < 0.05]. (2) Respiratory parameters: compared with values before drowning, PaO2/FiO2, VT, and Cdyn decreased immediately in both freshwater and seawater drowning groups, Ppeak was significantly increased; in addition, the values in the seawater drowning group were decreased or increased more significantly than freshwater drowning group [PaO2/FiO2 (mmHg): 37.83±1.99 vs. 60.42±5.23, VT (mL): 86.25±7.66 vs. 278.75±9.67, Cdyn (mL/cmH2O): 8.86±0.33 vs. 23.02±0.69, Ppeak (cmH2O, 1 cmH2O = 0.098 kPa): 42.17±2.69 vs. 17.67±1.15, all P < 0.01]. In addition, PaO2/FiO2 in the freshwater drowning group was gradually increased over time, while the seawater group continued to decline. (3) Pulmonary circulation hemodynamic parameters: PAS, PAD, PAWP at the time of immediately after drowning in both freshwater and seawater groups were significantly higher than before drowning; in addition, the freshwater drowning group was significantly higher than the seawater drowning group [PAS (mmHg): 34.58±2.87 vs. 26.75±1.66, PAD (mmHg): 27.25±1.22 vs. 16.75±0.87, PAWP (mmHg): 27.83±1.85 vs. 11.75±1.82, all P < 0.01]. Thereafter, PAS and PAD in the freshwater drowning group gradually decreased, while the parameters in the seawater drown group continued to increase. PAWP gradually decreased after freshwater or seawater drowning, and recovered to pre-drowning levels 120 minutes after drowning and 30 minutes after drowning, respectively. EVLW continued to increase after freshwater drowning, reaching a peak at 30 minutes, and then decreased, until 120 minutes after drowning was still significantly higher than that before drowning (mL/kg: 10.73±1.27 vs. 7.67±0.69, P < 0.01); EVLW could not be measured. (4) Residual water in the respiratory tract: residual water in the freshwater drowning group was significantly less than that in the seawater drowning group (mL: 164.33±25.21 vs. 557.33±45.23, P < 0.01). (5) HE staining: partial alveolar atrophied in the freshwater drowning group, some alveolar spaces were broken, alveolar spaces and alveolar cavity showed a little powdery substance deposition; it was noted that alveolar expanded in the seawater drowning group, alveolar spaces were broken and bleeding and edema were obvious in the interstitial space. CONCLUSIONS: The effect of seawater drowning on the respiratory mechanics and pulmonary circulation of animals is more obvious than that of freshwater drowned animals, and the amount of residual water in the respiratory tract is also significantly more than that of freshwater drowned animals.

Structural engineering of bilayer PtSe2 thin films: a first-principles study.

PtSe2 is an emerging layered two-dimensional material of applied interest. Its monolayer shows promising properties for applications in electronic devices, while the bandgap of a multilayer PtSe2 film can be tuned via changing its thickness. In this work the bilayer PtSe2 thin films are investigated as an example of structural engineering with first-principles calculations. Various van der Waals corrections schemes are firstly discussed, and the optB86b scheme shows a better description of the semiconductor-metal transition for PtSe2 films. Six bilayer PtSe2 thin films in different stacking modes are constructed in order to structurally tune the electronic and transport properties. The bandgap can be effectively broadened with the structural engineering for wider potential applications. The carrier mobility, dynamical stability and Raman spectra are also calculated and discussed.

Tunable electronic properties of monolayer MnPSe3/MoTe2 heterostructure: a first principles study.

The construction of van der Waals heterostructures is deemed to be a novel scheme to circumvent the shortcomings of their components and bear potentials for applications in electronic devices. Here we systematically investigate the structural and electronic properties of a monolayer MnPSe3/MoTe2 heterostructure with the first principles calculations. The heterostructure stablizes in the antiferromagnetic state and possesses a typical type-II band alignment, with which the photoexcited electrons and holes can be effectively separated and their fast recombination can hence be suppressed. Meanwhile, an inherent electric field is observed at the interface between MnPSe3 and MoTe2. Interestingly, the band gap of the heterostructure shows a quasi-linear dependence on the external electric field applied, and is tunable within the semiconductor to semimetal range. The tunability with applied strain is also investigated and discussed.

The functionality of surface hydroxyls on selective CH4 generation from photoreduction of CO2 over SiC nanosheets.

The surface hydroxyls on SiC nanosheets provide local protons, stabilize intermediates and localize photogenerated electrons in the deep photoreduction of CO2, significantly promoting the efficiency and selectivity of CH4 yield. This study describes the surface reaction for selective CO2 reduction based on both thermodynamic and kinetic requirements.

Charge Engineering of Mo2C@Defect-Rich N-Doped Carbon Nanosheets for Efficient Electrocatalytic H2 Evolution.

Charge engineering of carbon materials with many defects shows great potential in electrocatalysis, and molybdenum carbide (Mo2C) is one of the noble-metal-free electrocatalysts with the most potential. Herein, we study the Mo2C on pyridinic nitrogen-doped defective carbon sheets (MoNCs) as catalysts for the hydrogen evolution reaction. Theoretical calculations imply that the introduction of Mo2C produces a graphene wave structure, which in some senses behaves like N doping to form localized charges. Being an active electrocatalyst, MoNCs demonstrate a Tafel slope as low as 60.6 mV dec-1 and high durability of up to 10 h in acidic media. Besides charge engineering, plentiful defects and hierarchical morphology also contribute to good performance. This work underlines the importance of charge engineering to boost catalytic performance.