Search

Background: Esketamine is increasingly used in clinical anesthesia. The effect of esketamine on the blood flow velocity of the middle cerebral artery has a clinical guiding effect. To investigate the effect of esketamine combined with propofol-induced general anesthesia for endotracheal intubation on the blood flow velocity of middle cerebral artery and hemodynamics during the induction period. Methods: The randomized clinical trial included 80 patients aged 20-65 years who would undergo non-intracranial elective surgery under general anesthesia in our hospital from May 2022 to May 2023. The participants were divided into two groups based on anesthesia drugs: sufentanil 0.5μg/kg (group C) or 1.5mg/kg esketamine (group E). The primary outcome was variation value in average cerebral blood velocity. The secondary outcomes included cerebral blood flow velocities (CBFV), blood pressure (BP) and heart rate (HR) at four different time points: before induction of general anesthesia (T0), 1 min after the induction drug injected (T1), before endotracheal intubation (T2), and 1min after endotracheal intubation (T3). The occurrence of hypotension, hypertension, tearing and choking during induction was also documented. Results: The variation of average CBFV from time T0 to T2(ΔVm1) and the variation from time T3 to T0 (ΔVm2) were not obviously different. The median consumption of intraoperative sufentanil in group C was obviously lower than that in group E. At T1, the mean HR of group E was significantly higher than that of group C. At T2 and T3, the BP and HR of group E were obviously higher than that of group C. At T2, the CBFV in the group E were obviously higher than those in the group C. The incidence of hypotension was significantly reduced in the group E compared with the group C. There were no differences in the other outcomes. Conclusions: The induction of esketamine combined with propofol does not increase the blood flow velocity of middle cerebral artery. Esketamine is advantageous in maintaining hemodynamic stability during induction. Furthermore, the administration of esketamine did not result in an increased incidence of adverse effects. Trial Registration: 15/06/2023 clinicaltrials.gov ChiCTR2300072518 https://www.chictr.org.cn/bin/project/edit?pid=176675. [ABSTRACT FROM AUTHOR]

Purpose: To assess the efficacy of pericapsular nerve group (PENG) block combined with lateral femoral cutaneous nerve (LFCN) block in controlling postoperative pain and promoting recovery of lower extremity after total hip arthroplasty (THA), and to compare its effectiveness with supra-inguinal fascia iliaca compartment block (S-FICB). Materials and methods: 92 patients undergoing THA with general anesthesia were randomly allocated to receive either a PENG with LFCN block (n = 46) using 30 ml 0.33% ropivacaine (20 ml for PENG block, 10 ml for LFCN block), or an S-FICB (n = 46) using 30 ml 0.33% ropivacaine. The primary outcome was the time to first postoperative walk. The secondary outcomes included intraoperative remifentanil consumption, postoperative hip flexion degree and muscle strength of the operative lower limbs in the supine position, pain scores (static and dynamic), rescue analgesia, postoperative nausea and vomiting (PONV), and nerve block-related complications. Results: The combination of PENG with LFCN blocks resulted in an earlier first postoperative walking time (19.6 ± 9.6 h vs 26.5 ± 8.2 h, P < 0.01), greater postoperative hip flexion degree at 6 h, 24 h and 48 h (all P < 0.01), and higher muscle strength of the operative lower limbs at 6 h after surgery (P = 0.03) compared to S-FICB. The difference in pain scores (static and dynamic) was only statistically significant at 48 h (P < 0.05). There were no differences in the other outcomes. Conclusions: PENG with LFCN blocks is more effective than S-FICB in shortening the time to first postoperative walk and preservation hip motion after THA, which makes it a suitable addition to enhanced recovery programs following surgery. [ABSTRACT FROM AUTHOR]

The thermal transport properties of minerals at high temperature and high pressure are important for understanding the internal evolution and dynamic processes of the Earth. Here, we carry out a detailed study on the lattice thermal conductivities ( κ latt ) of Mg 2 SiO 4 under upper mantle and transition zone conditions by anharmonic lattice dynamics method. The calculations show that the κ latt of Mg 2 SiO 4 increase with the phase transitions, which agree with the previous measurements and are attributed to the increase of lifetime and group velocity under extreme conditions. The κ latt of Mg 2 SiO 4 along the geotherm shows a 64 % jump at 410 km and 71 % jump at 520 km . The anisotropy in the κ latt of olivine and wadsleyite decreases with increasing pressure. The present findings offer a fundamental knowledge of the κ latt of Mg 2 SiO 4 under extreme conditions, which are crucially important for understanding the thermal transport processes in the Earth. [ABSTRACT FROM AUTHOR]

Background: Hip arthroplasty is effective in treating hip diseases, such as osteoarthritis and hip fracture, but it often brings severe trauma and pain. In recent years, ultrasound-guided supra-inguinal fascia iliaca compartment block(S-FICB) has become a widely used nerve block method for analgesia in hip arthroplasty. Methods: Fifty-three patients preparing for hip arthroplasty were prospectively enrolled. S-FICB was performed under ultrasound guidance, and inject 0.33% ropivacaine into the space. Using the biased-coin design (BCD) sequential allocation method. The initial volume of 0.33% ropivacaine was 30ml. In case of failure, the next patient received a higher volume (defined as the previous volume with an increment of 1.2 mL). If the previous patient had a successful block, the next patient was randomized to a lower volume (defined as the previous volume with a decrement of 1.2 mL), with a probability of b = 0.05, or the same volume, with a probability of 1 − b = 0.95. The study was stopped when 45 successful blocks were achieved. Results: Forty-five patients (84.9%) were blocked successfully. The 95% effective volume (EV95) was 34.06ml (95%CI 33.35 ~ 36.28ml). There were 31 patients with non-fracture in this study. The quadriceps muscle strength decreased in only two patients. Moreover, they both received 34.8ml of ropivacaine for S-FICB. Twenty-two patients had hip fractures. There were 3 patients (14%) with failed blocks and 19 patients (86%) with successful blocks. However, all fracture patients experienced less pain after S-FICB. Conclusion: EV95 of 0.33% ropivacaine for ultrasound-guided S-FICB was 34.06ml. Trial registration: The trial was registered at the Chinese Clinical Trial Registry (registration number: ChiCTR2100052214, registration date: 2021 October 22). [ABSTRACT FROM AUTHOR]

Purpose: Ultrasound-guided thoracic paravertebral block (TPVB) has become increasingly popular for postoperative analgesia after thoracic surgery. We designed this prospective, randomized, double-blind, placebo-controlled trial to investigate the effect of TPVB on blood coagulation in patients after thoracoscopic lobectomy. Patients and Methods: Sixty patients scheduled for thoracoscopic lobectomy were randomly allocated to two groups. Patients underwent ultrasound-guided TPVB with 0.33% ropivacaine (T group) or 0.9% saline (C group) at the end of the surgery under general anesthesia. Patient-controlled intravenous analgesia (PCIA) was administered for both group after the surgery. The primary outcome was the thromboelastogram (TEG) parameters before anesthesia (T0), at the end of operation (T1) and in 1 day (T2) and 2 days (T3) after the operation, the second outcomes were the analgesic effect and the amount of intraoperative opioid consumption, operation time, infusion volume, blood loss and urine volume. Results: The visual analog scale (VAS) scores in group T were lower than group C (P < 0.05). In group T, compared with T0, the R value at T1 and T2 is significantly reduced, and the K value at T1 were significantly shortened, the α-angle and MA value at T1 were significantly increased (P < 0.05). In group C, compared with T0, the R value and K value were significantly shortened, the α-angle and MA value were significantly increased at all postoperative time points (P < 0.05). Compared with group C at the same time point, the R and K values of group T were significantly longer, and the α-angle and MA values were significantly reduced at T2 and T3 points, with statistically significant differences (P< 0.05). Conclusion: TPVB is beneficial to improve postoperative hypercoagulability and promote postoperative rehabilitation of patients after thoracoscopic lobectomy. [ABSTRACT FROM AUTHOR]

We present a stoichiometry-dependent structural phase transition in SrRuO3 film on SrTiO3 substrate. The oxygen stoichiometry in the films was varied by changing the oxygen partial pressure P(O2) during the deposition process. For SrRuO3 films with P(O2) ≥ 60 mTorr, they exhibited a pseudo-orthorhombic structure with in-plane uniaxial magnetic anisotropy. On the other hand for films with P(O2) ≤ 45 mTorr, the tetragonal SrRuO3 phase with a perpendicular uniaxial magnetic anisotropy was stabilized at room temperature. The big difference in the magnetic anisotropy of these two SrRuO3 phases was shown to be closely linked to their respective RuO6 octahedral rotation patterns: the RuO6 octahedra rotate differently along the two orthogonal in-plane directions in the pseudo-orthorhombic phase, whereas in the tetragonal phase only octahedral rotations around z-axis are present and the octahedral tilts along the in-plane axes are diminished. First-principles calculations show that such a suppression of the RuO6 octahedra tilting in the tetragonal phase arises from the oxygen vacancies at the octahedral apex (along z-axis). This work demonstrates that the stoichiometry plays an important role in determining the octahedral rotations and tilts in the perovskite materials, which may induce new phases with distinctively different structural symmetry and physical property. [ABSTRACT FROM AUTHOR]

First principles and quasi-harmonic Debye model have been used to study the thermodynamic properties, enthalpies, electronic and optical properties of MgO up to the core-mantle boundary (CMB) condition (137 GPa and 3700 K). Thermodynamic properties calculation includes thermal expansion coefficient and capacity, which have been studied up to the CMB pressure (137 GPa) and temperature (3700 K) by the Debye model with generalized gradient approximation (GGA) and local-density approximation (LDA). First principles with hybrid functional method (PBE0) has been used to calculate the electronic and optical properties under pressure up to 137 GPa and 0 K. Our results show the Debye model with LDA and first principles with PBE0 can provide accurate thermodynamic properties, enthalpies, electronic and optical properties. Calculated enthalpies show that MgO keep NaCl (B1) structure up to 137 GPa. And MgO is a direct bandgap insulator with a 7.23 eV calculated bandgap. The bandgap increased with increasing pressure, which will induce a blue shift of optical properties. We also calculated the density of states (DOS) and discussed the relation between DOS and band, optical properties. Equations were used to fit the relations between pressure and bandgaps, absorption coefficient (()) of MgO. The equations can be used to evaluate pressure after careful calibration. Our calculations can not only be used to identify some geological processes, but also offer a reference to the applications of MgO in the future. [ABSTRACT FROM AUTHOR]

Transition metal (TM) modification is a common strategy for converting an earth-abundant mineral into a cost-effective catalyst for industrial applications. Among a variety of minerals, Al2SiO5, which has three phases, andalusite, sillimanite and kyanite, is emerging as a promising candidate for new catalyst development. In this paper, we use Mn to demonstrate the rationale of 3d TM doping at the Al sites in each of these three phases through first-principles calculations and the cluster expansion method. The results of cluster expansion show that Mn has a strong site preference for the six-coordinated Al octahedral chains in the andalusite and sillimanite phases, while distributing randomly in the kyanite phase. Moreover, Mn can only replace Al in sillimanite and kyanite in low concentrations; however, higher concentrations of Mn can replace Al in andalusite. We found that the concentration sensitivity is due to the Jahn–Teller distortion and 3d orbital splitting. This finding can also explain the low doping concentrations of other 3d TMs (Fe, Cr and V) in Al2SiO5 compounds. Based on the calculated Helmholtz free energy, we constructed a (MnxAl1−x)AlSiO5 temperature-composite phase diagram, which explains the physical mechanisms behind the results for 3d transition metal doping and phase transitions in Al2SiO5. This work could shed light on the related physics, chemistry, and geoscience of (MnxAl1−x)AlSiO5, and more importantly, a design rationale for the engineering of cheap catalysts. [ABSTRACT FROM AUTHOR]

We used the CASTEP program with a GGA+ U method to study the effects of Cu doping on the formation energy, electronic and optical properties of V-doped ZnO. The calculated enthalpies show that Cu inclines stay near V. The formation energy shows Cu and V codoping is easy to form in an oxygen atmosphere. Vanadium introduces an impurity band level and Cu widen the level. The relation between the band and density of states (DOS) has been discussed. The calculated absorption coefficient ( α( ω)) shifts to lower energy (red shift). The absorption coefficient also has a broad increased peak in the green energy region (around 530 nm). We also calculated the other optical constants of Cu and V codoped ZnO. The relation between the optical properties and DOS has been discussed. Our calculations not only can explain the experiment and but also clarify the mechanism and role of Cu on the optical properties of V-doped ZnO. Our study provides a reference and method for improving codoping content and absorption in the visible region of V-doped ZnO. We also provide a reference in designing optical devices base on V-doped ZnO. [ABSTRACT FROM AUTHOR]

The spin states, elastic properties and seismic velocities of ferric iron-bearing post-perovskite MgSiO (pPv) with single oxygen vacancy [Mg(Si,Fe)O and Mg(Si,Fe)O] were calculated by first principles based on density functional theory. The effects of ferric iron and oxygen vacancy on seismic waves were studied for the host pPv subjected to a hydrostatic pressure. Calculations revealed a new spin transition from intermediate-spin to low-spin states with increasing pressure. As a result, the volume was reduced and the elastic constants were modified, producing a clear decrease in the seismic velocities of both compressive wave and shear wave due to the reduction of bulk modulus and shear modulus. The ferric iron and oxygen vacancy also had a minor effect on wave anisotropy. [ABSTRACT FROM AUTHOR]

Adsorption of single gold (Au) atom at three kinds of sites (hollow, bridge and top) on the hydroxylated β-cristobalite SiO (1 1 1) surface was studied using the first-principles calculations with general gradient approximation (GGA). The results of adsorption energies and density of electronic states (DOS) suggest that the hollow and bridge sites have the basically equal capability of binding Au, while the ability of the Top site is weaker. Two new energy levels emerge after the adsorption at all sites; in DOS of the Hollow configuration, one locates at −0.15 eV, composed of Au 5d and O 2p electronic states, another just crosses through the Fermi level, consisting of Au 6s, H 1s and O 2p. In addition, Mulliken population analyses indicate that electron transfer takes place between the Au atom and the surface H and O atoms in the Hollow and Bridge configurations, which can be used to interpret the adsorption of Au onto the positions. However, neither H nor O chemically bonds with Au atom. [ABSTRACT FROM AUTHOR]

In this study, density-functional theory plane-wave pseudopotential method was employed to investigate several oxygen vacancies on TiO2 anatase (101) surface. At first, a suitable defect-free slab model has been established by analyzing the surface energies and the atomic relaxations influenced by different technical parameters. The formation energies of different kinds of oxygen vacancies in the outermost layer have also been compared as well as the atomic displacement of the defective surfaces. It was found that the presence of bridging oxygen vacancy is more energetically favored and causes larger atomic displacement than other types of surface oxygen vacancies. The reactivity of oxygen vacancies has also been tested by both molecular and dissociated oxygen adsorption. Furthermore, we discussed the configurations and the electronic properties of O2-adsorbed surface, and found that the appearance of oxygen adsorbate-induced states in the band gap can make the surface sensitive to visible light. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of BN(5, 5) and C(5, 5) nanotubes under pressure are studied by using first principles calculations. In our study range, BN(5, 5) undergoes obvious elliptical distortion, while for C(5, 5) the cross section first becomes an ellipse and then, under further pressure, is flattened. The band gap of BN(5, 5) decreases with increasing pressure, which is inverse to that of zinc blende BN, whereas for C(5, 5) the metallicity is always preserved under high pressure. The population of charge density indicates that intertube bonding is formed under pressure. We also find that BN(5, 5) may collapse, and a new polymer material based on C(5, 5) is formed by applying pressure. [ABSTRACT FROM AUTHOR]

It is demonstrated that an asymmetric Fabry–Pérot fiber-optic pressure sensor is capable to precisely measure liquid levels. They are directly proportional to pressures that can modulate cavity length of Fabry–Pérot cavity. As a result, the sensor can operate over a linear region of an interference fringe that enables liquid-levels interrogation by measuring the reflected intensity. Experimental results show the resolving power of 0.4 mm, sensitivity of 2.4 mV/mm, and precision of 1 mm over range of 2.3 m (water) can be achieved. The sensor can measure liquid levels accurately, continuously, and automatically in flammable and explosive circumstances. [ABSTRACT FROM AUTHOR]

Epitaxial SrRuO3 films were grown under different oxygen partial pressures inducing different amounts of oxygen vacancies. In spite of microstructural disorders, a considerable improvement in the conductivity was observed at ambient temperature with increasing the oxygen vacancies. The oxygen vacancies are responsible for the conductivity improvement by enhancing the orbital overlap between Ru dz2 and O pz orbitals. The finding indicates that the oxygen vacancy plays an important role in determining the transport properties of perovskite oxides, by modifying their electronic structures. [ABSTRACT FROM AUTHOR]