The sniffing position facilitated easier light wand guided endotracheal intubation compared with the neutral position with chin-lift.

BACKGROUND: Traditionally, the patient's head is placed in a neutral position with a chin-lift to facilitate light wand guided endotracheal intubation. However, our study found that the sniffing position was more effective. In this study, we aimed to compare the two positions of light wand guided endotracheal intubation. METHODS: Sixty adult patients were included in the study, after obtaining informed consent, and were randomly assigned to one of two groups: a control group in a neutral position with a chin-lift (group C, n = 30) and a sniffing position group (group S, n = 30). In group C, the anesthesiologist inserted a light wand after lifting the patient's mandible using the thumb of their non-dominant hand inside the patient's mouth. In group S, a light wand was inserted after the patient's head was flexed with the neck extended. We assessed variables such as light-search time, number of intubation attempts, time to achieve intubation, and side effects including blood tinge on the endotracheal tube, hoarseness, sore throat, and anesthesiologist satisfaction. RESULTS: The light-search and intubation times were shorter in group S than in group C. The incidence of blood tinge on the endotracheal tube was higher in group C than in group S. Anesthesiologist satisfaction was higher in group S than in group C. CONCLUSIONS: The sniffing position was more effective in facilitating light wand guided endotracheal intubation than the neutral position with a chin-lift.

Various defects in graphene: a review.

Pristine graphene has been considered one of the most promising materials because of its excellent physical and chemical properties. However, various defects in graphene produced during synthesis or fabrication hinder its performance for applications such as electronic devices, transparent electrodes, and spintronic devices. Due to its intrinsic bandgap and nonmagnetic nature, it cannot be used in nanoelectronics or spintronics. Intrinsic and extrinsic defects are ultimately introduced to tailor electronic and magnetic properties and take advantage of their hidden potential. This article emphasizes the current advancement of intrinsic and extrinsic defects in graphene for potential applications. We also discuss the limitations and outlook for such defects in graphene.

Emergent Topological Hall Effect from Exchange Coupling in Ferromagnetic Cr2Te3/Noncoplanar Antiferromagnetic Cr2Se3 Bilayers.

The topological Hall effect has been observed in magnetic materials of complex spin structures or bilayers of trivial magnets and strong spin-orbit-coupled systems. In view of current attention on dissipationless topological electronics, the occurrence of the topological Hall effect in new systems or by an unexpected mechanism is fascinating. Here, we report a robust topological Hall effect generated in bilayers of a ferromagnet and a noncoplanar antiferromagnet, from the interfacial Dzyaloshinskii-Moriya interaction due to the exchange coupling of magnetic layers. Molecular beam epitaxy has been utilized to fabricate heterostructures of a ferromagnetic metal Cr2Te3 and a noncoplanar antiferromagnet Cr2Se3. A significant topological Hall effect at low temperature implies the development of nontrivial spin chirality, and density functional theory calculations explain the correlation of the Dzyaloshinskii-Moriya interaction increase and inversion symmetry breaking at the interface. The presence of noncoplanar ordering in the antiferromagnet plays a pivotal role in producing the topological Hall effect. Our results suggest that the exchange coupling in ferromagnet/noncoplanar antiferromagnet bilayers could be an alternative mechanism toward topologically protected magnetic structures.

Comparison of two-lung and one-lung ventilation in bilateral video-assisted thoracoscopic extended thymectomy in myasthenia gravis: a retrospective study.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease, and early thymectomy is recommended. Since the introduction of video-assisted thoracoscopic surgery, the safety and effectiveness of carbon dioxide insufflation in the thoracic cavity (capnothorax) has been controversial. This study aimed to compare the safety and effectiveness of ventilation methods in bilateral video-assisted thoracoscopic extended thymectomy (BVET) with capnothorax. METHODS: We retrospectively investigated the medical records of patients with MG who underwent BVET between August 2016 and January 2018. Patients were divided into two groups: group D (n = 26) for one-lung ventilation and group S (n = 28) for two-lung ventilation. We set nine anesthesia time points (T0-T8) and collected respiratory and hemodynamic variables, including arterial O2 index (PaO2/FiO2). RESULTS: SpO2 at T1-T3 and T8 was significantly lower in group D than in group S. The FiO2 in group S was lower than that in group D at all time points. The number of PaO2/FiO2 ≤ 300 and PaO2/FiO2 ≤ 200 events was significantly higher in group D than in group S. Hemodynamic variables were not significantly different between the two groups at any time point. The duration of surgery and anesthesia was shorter in group S than in group D. CONCLUSIONS: This retrospective study suggests that anesthesia using two-lung ventilation during BVET with capnothorax is a safe and effective method to improve lung oxygenation and reduce anesthesia time.

Safety Monitoring after the BNT162b2 COVID-19 Vaccine among Adults Aged 75 Years or Older.

BACKGROUND: Older adults are given high priority for coronavirus disease 2019 (COVID-19) vaccination; however, little is known about the safety of vaccines. This study was conducted to examine the safety of the COVID-19 vaccine for people who were ≥ 75 years of age, specifically those who first took two doses of the vaccine at the COVID-19 central vaccination center in South Korea. METHODS: Safety monitoring after the BNT162b2 vaccine was conducted in three ways for older adults who received the first dose of the vaccine at our center between April 5 and April 23, 2021. For immediate adverse reactions, every person who was vaccinated was observed for 15-30 minutes after injection at the center. For active surveillance, a telephone interview was conducted for stratified randomly sampled people after 7 days of each vaccination to enquire regarding types of adverse reactions they experienced, and its severity and duration. For passive surveillance, reported adverse event data were collected from the COVID-19 vaccine adverse event following immunization (AEFI) surveillance system-run by the Korea Disease Control and Prevention Agency (KDCA). The data were then reviewed. RESULTS: In total, 2,123 older adults received at least one vaccine dose during the study period. The frequency of acute adverse reactions that developed during the observed 15-30 minutes after injection was 8.5 cases per 1,000 doses. None of the reactions was assessed as acute allergic reactions to the vaccine and no cases required special treatment or drug administration. Overall, 638 people were followed up at least once by telephone interview 7 days post vaccination. The overall response rate was 82.3%. The rates of local reactions were 50.3% after the first dose and 45.2% after the second dose, and the rates of systemic reactions were 15.2% and 26.0%, respectively. During the study period, 23 medically attended adverse events (5.4 cases per 1,000 administered doses) were reported to the KDCA AEFI surveillance system. The most common symptoms of medically attended cases were nonspecific general weakness (26%) and dizziness (26%), followed by muscle pain (22%), headache (13%), fever (13%), and skin rash or urticaria (13%). Among them, there were five serious adverse events reported, which required hospitalization, including one death. However, most of them were not related to the vaccines. CONCLUSION: BNT162b2 vaccination was tolerable among adults who were ≥ 75 years of age.

Nanoporous Silver Telluride for Active Hydrogen Evolution.

Silver-based nanomaterials have been versatile building blocks of various photoassisted energy applications; however, they have demonstrated poor electrochemical catalytic performance and stability, in particular, in acidic environments. Here we report a stable and high-performance electrochemical catalyst of silver telluride (AgTe) for the hydrogen evolution reaction (HER), which was synthesized with a nanoporous structure by an electrochemical synthesis method. X-ray spectroscopy techniques on the nanometer scale and high-resolution transmission electron microscopy revealed an orthorhombic structure of nanoporous AgTe with precise lattice constants. First-principles calculations show that the AgTe surface possesses highly active catalytic sites for the HER with an optimized Gibbs free energy change of hydrogen adsorption (-0.005 eV). Our nanoporous AgTe demonstrates exceptional stability and performance for the HER, an overpotential of 27 mV, and a Tafel slope of 33 mV/dec. As a stable catalyst for hydrogen production, AgTe is comparable to platinum-based catalysts and provides a breakthrough for high-performance electrochemical catalysts.

Analgesic effect of ropivacaine with fentanyl in comparison with ropivacaine alone for continuous femoral nerve block after knee replacement arthroplasty: a prospective, randomized, double-blinded study.

BACKGROUND: The analgesic effect of perineural opioid in clinical practice are still controversial. This randomized controlled trial compared analgesic effect of ropivacaine with fentanyl or ropivacaine alone for continuous femoral nerve block following unilateral total knee arthroplasty. METHODS: Fourty patients of ASA PS Ⅰ or Ⅱ receiving total knee arthroplasty with spinal anesthesia were enlisted and randomly allocated into two groups. Group R; bolus injection of 0.375% ropivacaine, 30 ml and an infusion of 0.2% ropivacaine at 8 ml/h (n = 20). Group RF; 0.375% ropivacaine, 29 ml added with 50 µg of fentanyl as a bolus and an infusion of 0.2% ropivacaine mixed with 1 µg/ml of fentanyl at 8 ml/h (n = 20). Local anesthetic infusion via a femoral nerve catheter was started at the end of operation and continued for 48 h. Intravenous patient-controlled analgesia with hydromorphone (0.15 mg/ml, 0-1-10) were used for adjuvant analgesics. Position of catheter tip and contrast distribution, visual analogue scale of pain, hydromorphone consumption, side effects were recorded for 48 h after operation. Patient satisfaction for the pain control received were noted. RESULTS: The pain visual analogue scale, incidences of side effects and satisfaction were not different between the two groups (P > 0.05), but the hydromorphone usage at 48 h after operation were lower in the Group RF than in the Group R (P = 0.047). CONCLUSIONS: The analgesic effect of ropivacaine with fentanyl for continuous femoral nerve block after knee replacement arthroplasty was not superior to that of the ropivacaine alone.

Emergency exploratory laparotomy in a COVID-19 patient - A case report.

BACKGROUND: Surgeries in patients with coronavirus disease 2019 (COVID-19) put medical staff at a high risk of infection. We report the anesthetic management and infection control of a mechanically ventilated COVID-19 patient who underwent exploratory laparotomy for suspected duodenal ulcer perforation. CASE: A 73-year-old man, mechanically ventilated for confirmed COVID-19, showed clinical and radiographic signs of a perforated duodenal ulcer, and he was transferred under sedation and intubation to a negative-pressure operating room. The operating and assistant staff wore personal protective equipment. High-efficiency particulate absorbing filters were inserted into the expiratory circuits of the anesthesia machine and portable ventilator. No participating staff contracted COVID-19, although the patient later died due to pneumonia. CONCLUSIONS: This report can contribute to establishing clinical guidelines for the surgical management and operation room setting of COVID-19 patients.

Equilibrium structures of water molecules confined within a multiply connected carbon nanotube: a molecular dynamics study.

Water confinement inside a carbon nanotube (CNT) has been one of the most exciting subjects of both experimental and theoretical interest. Most of the previous studies, however, considered CNT structures with simple cylindrical shapes. In this paper, we report a classical molecular dynamics study of the equilibrium structural arrangement of water molecules confined in a multiply connected carbon nanotube (MCCNT) containing two Y-junctions. We investigate the structural arrangement of the water molecules in the MCCNT in terms of the density of water molecules and the average number of hydrogen bonds per water molecule. Our results show that the structural rearrangement of the H2O molecules takes place several angstroms ahead of the Y-junction, rather than only at the CNT junction itself. This phenomenon arises because it is difficult to match the boundary condition for hydrogen bonding in the region where two different hydrogen-bonded structures are interconnected with each other.

Fabrication of Robust Hydrogen Evolution Reaction Electrocatalyst Using Ag2Se by Vacuum Evaporation.

Much research has been done on reliable and low-cost electrocatalysts for hydrogen generation by water splitting. In this study, we synthesized thin films of silver selenide (Ag2Se) using a simple thermal evaporation route and demonstrated their electrocatalytic hydrogen evolution reaction (HER) activity. The Ag2Se catalysts show improved electrochemical surface area and good HER electrocatalytic behavior (367 mV overpotential @ 10 mA·cm-2, exchange current density: ~1.02 × 10-3 mA·cm-2, and Tafel slope: 53 mV·dec-1) in an acidic medium). The reliability was checked in 0.5 M sulfuric acid over 20 h. Our first-principles calculations show the optimal energy of hydrogen adsorption, which is consistent with experimental results. The works could be further extended for finding a new catalyst by associating the selenide, sulfide or telluride-based materials without complex catalyst synthesis procedures.

Role of reactive oxygen species at reperfusion stage in isoflurane preconditioning-induced neuroprotection.

In this in vivo and in vitro study, we aimed to investigate whether isoflurane preconditioning-induced neuronal protection is mediated by reactive oxygen species (ROS) signaling at the reperfusion stage. In the in vivo study, Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) and in the in vitro study, rat pheochromocytoma (PC12) cells were subjected to oxygen glucose deprivation (OGD). Isoflurane preconditioning was carried out prior to MCAO or OGD and the ROS scavenger, N-2-mercaptopropiopylglycine (2-MPG), was administered at the start of reperfusion. Infarct volume, neurological severity score, and TUNEL staining were analyzed in the in vivo study and cell viability, Bcl-2/Bax ratio, cleaved caspase 3/caspase 3 ratio, and ROS fluorescence intensity were measured in the in vitro study. In the in vivo study, infarct volume, neurological severity score, and TUNEL-positive cell count were significantly decreased with preconditioning but were abrogated by administration of 2-MPG. In the in vitro study, cell viability and Bcl-2/Bax ratio were significantly increased with preconditioning, and cleaved caspase-3/caspase-3 ratio and ROS fluorescence intensity were significantly decreased. Administration of 2-MPG for 10 min abrogated this preconditioning effect, but it did not abolish the protection when administered for 60 min of reperfusion. Isoflurane preconditioning-induced protection was abolished by ROS scavengers at the start of reperfusion, indicating that ROS signaling can mediate the isoflurane preconditioning effect, which suggests that the time window can be important.

Effects of intercalated atoms on electronic structure of graphene nanoribbon/hexagonal boron nitride stacked layer.

Using first-principles calculations, we investigate an atomic impurity at the interface of a van der Waals heterostructure (vdW heterostructure) consisting of a zigzag graphene nanoribbon (ZGNR) and a hexagonal boron nitride (h-BN) sheet. To find effects of atomic intercalation on geometrical and electronic properties of the ZGNR on the h-BN sheet, various types of impurity atoms are considered. The embedded atoms are initially placed at the edge or the middle of the ZGNR located on the h-BN sheet. Our results demonstrate that most of the impurity atoms are more stable at the edge than at the middle in all cases we consider. Especially, a nickel atom has the smallest energy difference (~0.15 eV) between the two embedding positions, which means that the Ni atom is relatively easy to intercalate in the structure. Finally, we discuss magnetic properties for the vdW heterostructure with an intercalated atom.

Anaphylactic shock after sugammadex administration, induced by formation of a sugammadex-rocuronium complex -a case report.

BACKGROUND: Sugammadex is a reversal agent for non-depolarizing neuromuscular blockers and widely used worldwide on account of its rapid and effective reversal from neuromuscular blockade, despite its advantages, multiple cases of sugammadex-induced anaphylactic shock have been reported. CASE: A 42-year-old man developed anaphylactic shock in the postanesthesia care unit. Initially, sugammadex was suspected as the causative agent, but an intradermal skin test revealed negative results. A further skin test was performed with sugammadex-rocuronium complex that yielded positive results. CONCLUSIONS: Anesthesiologists and healthcare providers should be aware of the possibility of anaphylaxis from the sugammadex-rocuronium complex, as well as from sugammadex or rocuronium alone.

First-principles modeling of water permeation through periodically porous graphene derivatives.

Polyphenylene superhoneycomb network (PSN) and covalent triazine framework (CTF) are experimentally realized periodically porous graphene derivatives. Such ultrathin layers with homogeneously distributed pores of controllable sizes are highly desirable for applications in molecular separations such as water purification. The permeation energy barrier is expected to be a function of not only the pore size, but also the specific permeation trajectory as determined by hydrogen bonding interactions at the water-pore interface. Here, we report a detailed first-principles study of permeation of a single H2O molecule through a monolayer PSN and CTF-0, as well as its diffusion behavior inside a bilayer PSN. The calculated energy barrier of 1.44 eV indicates the infeasibility of using PSN as a water permeation membrane. However, the barrier decreases considerably to 0.94 eV when three C-H pairs at the pore are replaced with N atoms into CTF-0. Inside a bilayer PSN, we find facile interlayer sliding as well as interlayer expansion owing to out-of-plane reorientation of the H2O molecule. In all cases, the functional groups at the pore significantly alter the orientation of the H2O molecule and the corresponding barriers. Such atomistic insights at the porous interface would provide a valuable guidance in advancing rational pore design principles.

Edge-functionalization of armchair graphene nanoribbons with pentagonal-hexagonal edge structures.

Using density functional theory calculations, we have studied the edge-functionalization of armchair graphene nanoribbons (AGNRs) with pentagonal-hexagonal edge structures. While the AGNRs with pentagonal-hexagonal edge structures (labeled (5,6)-AGNRs) are metallic, the edge-functionalized (5,6)-AGNRs with substitutional atoms opens a band gap. We find that the band structures of edge-functionalized (5,6)-N-AGNRs by substitution resemble those of defect-free (N-1)-AGNR at the Γ point, whereas those at the X point show the original ones of the defect-free N-AGNR. The overall electronic structures of edge-functionalized (5,6)-AGNRs depend on the number of electrons, supplied by substitutional atoms, at the edges of functionalized (5,6)-AGNRs.

Ab initio study of aspirin adsorption on single-walled carbon and carbon nitride nanotubes.

Using density functional theory, we investigate the adsorption properties of acetylsalicylic acid (aspirin) on the outer surfaces of a (10,0) carbon nanotube (CNT) and a (8,0) triazine-based graphitic carbon nitride nanotube (CNNT). The adsorption energies for the CNNT and CNT are 0.67 and 0.51 eV, respectively, and hence, the aspirin molecule binds more strongly to the CNNT. The stronger adsorption energy for the binding to the CNNT is ascribed to the high reactivity of its nitrogen atoms with high electron affinity. The CNNT exhibits local electric dipole moments that cause strong charge redistribution in the adsorbed aspirin molecule. The influence of an external electric field on the adsorption of aspirin on the nanotubes is explored by examining modifications in their electronic band structures, partial densities of states, and charge distributions. An electric field applied along a particular direction is found to induce molecular states of aspirin that lie within the in-gap region of the CNNT. This implies that the CNNT can be potentially utilized for the detection of aspirin.

Study of Grains and Boundaries of Molybdenum Diselenide and Tungsten Diselenide Using Liquid Crystal.

Direct observation of grains and boundaries is a vital factor in altering the electrical and optoelectronic properties of transition metal dichalcogenides (TMDs), that is, MoSe2 and WSe2. Here, we report visualization of grains and boundaries of chemical vapor deposition grown MoSe2 and WSe2 on silicon, using optical birefringence of two-dimensional layer covered with nematic liquid crystal (LC). An in-depth study was performed to determine the alignment orientation of LC molecules and their correlation with other grains. Interestingly, we found that alignment of liquid crystal has discrete preferential orientations. From computational simulations, higher adsorption energy for the armchair direction was found to force LC molecules to align on it, compared to that of the zigzag direction. We believe that these TMDs with three-fold symmetric alignment could be utilized for display applications.

Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure.

Securing a semiconducting bandgap is essential for applying graphene layers in switching devices. Theoretical studies have suggested a created bulk bandgap in a graphene layer by introducing an asymmetry between the A and B sub-lattice sites. A recent transport measurement demonstrated the presence of a bandgap in a graphene layer where the asymmetry was introduced by placing a graphene layer on a hexagonal boron nitride (h-BN) substrate. Similar bandgap has been observed in graphene layers on metal substrates by local probe measurements; however, this phenomenon has not been observed in graphene layers on a near-insulating substrate. Here, we present bulk bandgap-like features in a graphene layer epitaxially grown on an h-BN substrate using scanning tunneling spectroscopy. We observed edge states at zigzag edges, edge resonances at armchair edges, and bandgap-like features in the bulk.

Exposure of isoflurane-treated cells to hyperoxia decreases cell viability and activates the mitochondrial apoptotic pathway.

Isoflurane has either neuroprotective or neurotoxic effects. High-dose oxygen is frequently used throughout the perioperative period. We hypothesized that hyperoxia will affect cell viability of rat pheochromocytoma (PC12) cells that were exposed to isoflurane and reactive oxygen species (ROS) may be involved. PC12 cells were exposed to 1.2% or 2.4% isoflurane for 6 or 24h respectively, and cell viability was evaluated. To investigate the effects of hyperoxia, PC12 cells were treated with 21%, 50%, or 95% oxygen and 2.4% isoflurane for 6h, and cell viability, TUNEL staining, ROS production, and expression of B-cell lymphoma 2 (BCL-2), BCL2-associated X protein (BAX), caspase-3 and beta-site APP cleaving enzyme (BACE) were measured. ROS involvement was evaluated using the ROS scavenger 2-mercaptopropiopylglycine (MPG). The viability of cells exposed to 2.4% isoflurane was lower than that of cells exposed to 1.2% isoflurane. Prolonged exposure (6h vs. 24h) to 2.4% isoflurane resulted in a profound reduction in cell viability. Treatment with 95% (but not 50%) oxygen enhanced the decrease in cell viability induced by 2.4% isoflurane alone. Levels of ROS, Bax, caspase-3 and BACE were increased, whereas expression of Bcl-2 was decreased, in cells treated with 95% oxygen plus 2.4% isoflurane compared with the control and 2.4% isoflurane plus air groups. MPG attenuated the effects of oxygen and isoflurane. In conclusion, isoflurane affects cell viability in a dose- and time-dependent manner. This effect is augmented by hyperoxia and may involve ROS, the mitochondrial apoptotic signaling pathway, and ß-amyloid protein.

DNA aptamer release from the DNA-SWNT hybrid by protein recognition.

Here we show the formation of the complex between a DNA aptamer and a single-walled carbon nanotube (SWNT) and its reaction with its target protein. The aptamer, which is specifically bound with thrombin, the target protein in this study, easily wraps and disperses the SWNT by noncovalent π-π stacking.