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.

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.

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.

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.

Electronic Properties of Bilayer Graphene Strongly Coupled to Interlayer Stacking and an External Electric Field.

Bilayer graphene (BLG) with a tunable band gap appears interesting as an alternative to graphene for practical applications; thus, its transport properties are being actively pursued. Using density functional theory and perturbation analysis, we investigated, under an external electric field, the electronic properties of BLG in various stackings relevant to recently observed complex structures. We established the first phase diagram summarizing the stacking-dependent gap openings of BLG for a given field. We further identified high-density midgap states, localized on grain boundaries, even under a strong field, which can considerably reduce the overall transport gap.

Is hexagonal boron nitride always good as a substrate for carbon nanotube-based devices?

Hexagonal boron nitride sheets have been noted especially for their enhanced properties as substrates for sp(2) carbon-based nanodevices. To evaluate whether such enhanced properties would be retained under various realistic conditions, we investigate the structural and electronic properties of semiconducting carbon nanotubes on perfect and defective hexagonal boron nitride sheets under an external electric field as well as with a metal impurity, using density functional theory. We verify that the use of a perfect hexagonal boron nitride sheet as a substrate indeed improves the device performances of carbon nanotubes, compared with the use of conventional substrates such as SiO2. We further show that even the hexagonal boron nitride with some defects can show better performance as a substrate. Our calculations, on the other hand, also suggest that some defective boron nitride layers with a monovacancy and a nickel impurity could bring about poor device behavior since the imperfections impair electrical conductivity due to residual scattering under an applied electric field.

Interlayer coupling enhancement in graphene/hexagonal boron nitride heterostructures by intercalated defects or vacancies.

Hexagonal boron nitride (hBN), a remarkable material with a two-dimensional atomic crystal structure, has the potential to fabricate heterostructures with unusual properties. We perform first-principles calculations to determine whether intercalated metal atoms and vacancies can mediate interfacial coupling and influence the structural and electronic properties of the graphene/hBN heterostructure. Metal impurity atoms (Li, K, Cr, Mn, Co, and Cu), acting as extrinsic defects between the graphene and hBN sheets, produce n-doped graphene. We also consider intrinsic vacancy defects and find that a boron monovacancy in hBN acts as a magnetic dopant for graphene, whereas a nitrogen monovacancy in hBN serves as a nonmagnetic dopant for graphene. In contrast, the smallest triangular vacancy defects in hBN are unlikely to result in significant changes in the electronic transport of graphene. Our findings reveal that a hBN layer with some vacancies or metal impurities enhances the interlayer coupling in the graphene/hBN heterostructure with respect to charge doping and electron scattering.

Formation of unconventional standing waves at graphene edges by valley mixing and pseudospin rotation.

We investigate the roles of the pseudospin and the valley degeneracy in electron scattering at graphene edges. It is found that they are strongly correlated with charge density modulations of short-wavelength oscillations and slowly decaying beat patterns in the electronic density profile. Theoretical analyses using nearest-neighbor tight-binding methods and first-principles density-functional theory calculations agree well with our experimental data from scanning tunneling microscopy. The armchair edge shows almost perfect intervalley scattering with pseudospin invariance regardless of the presence of the hydrogen atom at the edge, whereas the zigzag edge only allows for intravalley scattering with the change in the pseudospin orientation. The effect of structural defects at the graphene edges is also discussed.

Impact of perioperative COVID-19 infection on postoperative complication in cesarean section using Korean National Health insurance data.

The vulnerability during pregnancy has raised concerns about the potential impact of COVID-19 on obstetric anesthesia, an essential aspect of maternal care during cesarean section procedures. To evaluate the influence of COVID-19 infection on obstetric anesthesia during cesarean section, we analyzed the data from Korean National Health Insurance System (NHIS). This retrospective study utilized data from Korean NHIS. We included patients admitted with operation codes specific to cesarean section between January 1, 2020, and December 31, 2021. We classified patients into a COVID (+) group with a diagnosis code (U071) 30 days around surgery and a COVID (-) group without the code in the same period. The primary outcome was 30-day mortality that was defined as death within 30 days of admission due to any causes. Secondary outcomes were pulmonary complications (pneumonia, acute respiratory distress syndrome [ARDS], pulmonary thromboembolism [PTE], or unexpected postoperative mechanical ventilation), ICU admission, cardiac arrest, myocardial infarction [MI], other thromboembolic events, surgical site infection, sepsis, acute renal failure [ARF], and hepatic failure. Among 75,268 patients who underwent cesarean section, 107 had a COVID-19 diagnosis code, while 75,161 did not. After 1:4 propensity score matching (PSM), 535 patients were included in each group. 30-day mortality showed no significant differences between the two groups both before and after PSM. The COVID (+) group demonstrated significantly elevated rates of pneumonia, ARDS, PTE, and surgical site infection both before and after PSM. Hospital length of stay and admission costs were also significantly longer and higher, respectively, in the COVID (+) group before and after PSM. In subgroup analysis, no differences were observed in mortality and postoperative complications based on the anesthesia method after matching. COVID-19 infection is associated with increased rates of postoperative complications, including pneumonia, ARDS, PTE, surgical site infection, longer hospital stays, and increased admission costs, in patients who underwent cesarean section.

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.

Enhanced binding strength between metal nanoclusters and carbon nanotubes with an atomic nickel defect.

Using spin-polarized density functional theory calculations, we study binding properties of small metal nanoclusters (Cu(13) and Al(13)) onto carbon nanotubes (CNTs). On defect-free CNTs, the binding affinity with the Cu or Al cluster is very weak. When various defects such as vacancies, substitutional nickel defects, and nickel adatoms are introduced in CNTs to increase the binding strength, the binding energies of the metal nanoclusters increase substantially irrespective of types of defects. The effect of the Ni adatom is especially noticeable. Our results propose a method for improving the wettability of metal-CNT complex composites.

Enhanced formation of a confined nano-water meniscus using a 780 nm laser with a quartz tuning fork-atomic force microscope.

Demonstrated herein is the optical-field-induced enhancement of the formation of a confined nanowater meniscus using a distance-regulated quartz tuning fork-atomic force microscope (QTF-AFM) with a 780 nm laser. While a pulled optical fiber tip approaches the surface, the laser is suddenly turned on and focuses on the front spot of the tip by the shape of the pulled optical fiber, which plays the role of an objective lens and induces the gathering effect of the water molecules directed to the electromagnetic-field gradient in air. This phenomenon facilitates a new boundary condition to form a long-range confined nano-scale liquid bridge between the tip and the surface. After the pulling of the optical fiber, 20-nm-thick gold was sputtered on the apex (diameter: approximately 100 nm) of the tip to guide and focus the beam on the spot. The critical power of the laser to overcome the barrier for the formation of a new boundary is 100 microW at the distance of 22 nm from the substrate.

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.

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.

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.

Improvement of sleep-related breathing disorder in patients with end-stage renal disease after kidney transplantation.

Sleep-related breathing disorder (SRBD) is a common symptom of end-stage renal disease (ESRD). The aim of this study was to determine whether kidney transplantation improves SRBD. Twenty-four patients with ESRD, who were admitted for kidney transplantation, underwent a sleep study using a portable ventilation effort recorder on the night before transplantation. Of these patients, 20 could repeat the overnight monitoring two wk after the transplantation. The median apnea-hypopnea index (AHI) of the 20 patients was 13.5 (range, 2-40), and significantly reduced to 4.5 (range, 0-20) after transplantation (p = 0.003). This reduction was most prominent in 12 patients with SRBD, for whom the median AHI fell from 22 (range, 10-40) to 6.5 (range, 1-20; p = 0.010). SRBD improvement, defined as an AHI equal to or >50% and/or reduced to <10/h, was observed in eight of the 12 apneic patients. These results suggest that kidney transplantation may immediately improve SRBD in patients with ESRD. However, conclusions from this study should be taken with caution because of the limitations of our method, specifically the use of a portable recorder and a small number of patients.

A comparison of the effects of preanesthetic administration of crystalloid versus colloid on intrathecal spread of isobaric spinal anesthetics and cerebrospinal fluid movement.

BACKGROUND: Movement of the cerebrospinal fluid (CSF) is one of the most important factors in determining the intrathecal spread of isobaric spinal anesthetics. Preanesthetic administration of either crystalloid or colloid immediately before spinal anesthesia (preload) may result in different CSF pulsatile movement because of their different physical properties. We examined whether preload of crystalloid versus colloid may have different effects on the intrathecal spread of isobaric spinal anesthetics as a result of their different CSF dynamics regarding its pulsatile movement. METHODS: In a clinical study of isobaric spinal anesthesia, patients were allocated into 1 of 2 groups according to preload with either crystalloid (n = 30) or colloid (n = 30) before spinal anesthesia with 0.5 isobaric tetracaine. The pulsatile movements of CSF at the L2-3 intervertebral space and midportion of the aqueduct of Sylvius were also examined by magnetic resonance images in healthy volunteers (n = 23) at 0, 30, and 60 minutes after administering either crystalloid or colloid. RESULTS: In the clinical study, the time to reach the peak sensory block level was delayed significantly in the crystalloid preload group (27.2 ± 17.8 minutes; P < 0.01) compared with the colloid preload group (13.9 ± 7.0 minutes). The median sensory block levels of the crystalloid preload group at 15 minutes (T10, P < 0.05) and 20 minutes (T9.5, P < 0.05) were significantly lower than those (T8, T7, respectively) of the colloid preload group. In the magnetic resonance imaging study, cranially directed CSF pulsatile movement decreased significantly at the L2-3 intervertebral intrathecal space at 30 minutes after crystalloid administration, but not after colloid administration. The CSF production rate significantly increased at 30 minutes (637 µL/min, P < 0.05) after crystalloid preload compared with the baseline measurement (448 µL/min), and then slightly decreased (609 µL/min) at 60 minutes. In the colloid preload group, the CSF production rate was not statistically significant compared with the baseline measurement (464, 512, and 542 µL/min at baseline, 30, and 60 minutes, respectively). CONCLUSIONS: Compared with a colloid preload, which may be comparable to the no-preload condition, crystalloid preload prolonged the time to reach the peak sensory block level in isobaric spinal anesthesia, which might have been caused by a significant decrease in CSF pulsatile movement. This attenuated CSF pulsatile movement in the crystalloid preload group might have resulted from significant increases of CSF production.

Origins of dihydrogen binding to metal-inserted porphyrins: electric polarization and Kubas interaction.

Using density functional theory calculations, we have investigated the interactions between hydrogen molecules and metalloporphyrins. A metal atom, such as Ca or Ti, is introduced for incorporation in the central N(4) cavity. Within local density approximation (generalized gradient approximation), we find that the average binding energy of H(2) to the Ca atom is about 0.25 (0.1) eV/H(2) up to four H(2) molecules, whereas that to the Ti atom is about 0.6 (0.3) eV per H(2) up to two H(2) molecules. Our analysis of orbital hybridization between the inserted metal atom and molecular hydrogen shows that H(2) binds weakly to Ca-porphyrin through a weak electric polarization in dihydrogen, but is strongly hybridized with Ti-porphyrin through the Kubas interaction. The presence of d orbitals in Ti may explain the difference in the interaction types.

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.

Dissociation of single-strand DNA: single-walled carbon nanotube hybrids by Watson-Crick base-pairing.

It has been known that single-strand DNA wraps around a single-walled carbon nanotube (SWNT) by pi-stacking. In this paper it is demonstrated that such DNA is dissociated from the SWNT by Watson-Crick base-pairing with a complementary sequence. Measurement of field effect transistor characteristics indicates a shift of the electrical properties as a result of this "unwrapping" event. We further confirm the suggested process through Raman spectroscopy and gel electrophoresis. Experimental results are verified in view of atomistic mechanisms with molecular dynamics simulations and binding energy analyses.