[Effect of Flurbiprofen Axetil on Low-frequency Fluctuation Amplitude of Resting-state Functional Magnetic Resonance Imaging in Trigeminal Neuralgia].

Objective To observe the changes of brain function in patients with trigeminal neuralgia after administration of flurbiprofen axetil by using the resting-state functional magnetic resonance imaging(fMRI)and based on the amplitude of low-frequency fluctuation(ALFF). Methods Resting fMRI data of 20 patients with trigeminal neuralgia before and after treatment with flurbiprofen axetil were collected by 1.5T magnetic resonance imaging system.The resting fMRI data were pretreated by Statistical Parametric Mapping and DPABI(a toolbox for Data Processing and Analysis for Brain Imaging)software,and the difference of low-frequency oscillation amplitude of brain spontaneous activity before and after treatment with flurbiprofen axetil was analyzed by ALFF. Results The Visual Analogue Scale of pain intensity after flurbiprofen axetil injection was significantly lower than that before administration,and the pain relieved significantly(P=0.000).The ALFF values of right dorsolateral prefrontal lobe,bilateral medial prefrontal lobe,and right middle cingulate gyrus in patients treated with flurbiprofen axetil at rest were significantly lower than those before administration(P=0.000). Conclusions The analgesic effect of flurbiprofen axetil is exerted on the central system.This agent can inhibit the abnormal brain function caused by chronic pain stimulation and thus reduce pain.However,the specific mechanism needs further investigations.

Enhancement of tunneling current in phosphorene tunnel field effect transistors by surface defects.

The effects of the staggered double vacancies, hydrogen (H), 3d transition metals, for example cobalt, and semiconductor covalent atoms, for example, germanium, nitrogen, phosphorus (P) and silicon adsorption on the transport properties of monolayer phosphorene were studied using density functional theory and non-equilibrium Green's function formalism. It was observed that the performance of the phosphorene tunnel field effect transistors (TFETs) with an 8.8 nm scaling channel length could be improved most effectively, if the adatoms or vacancies were introduced at the source channel interface. For H and P doped devices, the upper limit of on-state currents of phosphorene TFETs were able to be quickly increased to 2465 µA µm-1 and 1652 µA µm-1, respectively, which not only outperformed the pristine sample, but also met the requirements for high performance logic applications for the next decade in the International Technology Roadmap for Semiconductors (ITRS). It was proved that the defect-induced band gap states make the effective tunneling path between the conduction band (CB) and valence band (VB) much shorter, so that the carriers can be injected easily from the left electrode, then transfer to the channel. In this regard, the tunneling properties of phosphorene TFETs can be manipulated using surface defects. In addition, the effects of spin polarization on the transport properties of doped phosphorene TFETs were also rigorously considered, H and P doped TFETs could achieve a high ON current of 1795 µA µm-1 and 1368 µA µm-1, respectively, which is closer to realistic nanodevices.

Increasing radiofrequency ablation volumes with the use of internally cooled electrodes and injected hydrochloric acid in ex vivo bovine livers.

PURPOSE: We used an impedance-controlled generator with an internally cooled electrode to perform radiofrequency ablation (RFA) in ex vivo bovine livers, with a single injection of either 38.5% sodium chloride (NaCl) or 10% hydrochloric acid (HCl), to determine the relative effects of these two solutions on tissue impedance, temperature and ablation volume. MATERIALS AND METHODS: We performed 10 ablations each with injections of NaCl (NaCl-RFA), HCl (HCl-RFA) or nothing (RFA-alone), with a power setting of 200 W for 15 minutes. We recorded tissue impedance before and after injection. We logged temperatures obtained from thermocouple probes positioned 5, 10, 15 and 20 mm from the internally cooled RF electrode. After ablation, we measured ablation zone longitudinal and transverse diameters, and we calculated a spherical ratio (SR) for each ablation. RESULTS: Mean post-injection impedance of 30.3 (standard deviation [SD] 2.5) ohms for HCl was significantly lower than that of 55.4 (SD 3.5) ohms for NaCl (p < .001). Mean maximum temperatures recorded at each respective distance from the RFA electrode were all highest for HCl-RFA and lowest for RFA-alone (p < .001). Mean longitudinal and transverse diameters after HCl-RFA (5.50 [SD 0.25] cm and 5.28 [SD 0.22] cm, respectively) were significantly larger than those after NaCl-RFA (4.24 [SD 0.35] cm and 3.55 [SD 0.43] cm, respectively) and after RFA-alone (3.60 [SD 0.10] cm and 2.70 [SD 0.13] cm, respectively) (p < .001). Mean SR after HCl-RFA (0.93, SD 0.02) was significantly higher than mean SR after NaCl-RFA (0.76, SD 0.06) and RFA-alone (0.72, SD 0.04) (p < .001). CONCLUSION: Monopolar, impedance-controlled RFA, with an internally cooled electrode and a single 10% HCl injection may allow larger tumors to be treated, potentially resulting in improved patient outcomes.

[Trans-extradural approach to resect trigeminal schwannomas involving the cavernous sinus region].

OBJECTIVE: To investigate the techniques and effect of extradural approach for the resection of trigeminal schwannomas involving the cavernous sinus. METHODS: Twenty-three patients (range 26-63 years, mean age 46.2 years) with trigeminal schwannomas involving the cavernous sinus treated by middle fossa extradural approach were retrospectively analyzed. Frontotemporal orbitozygomatic extradural approach was performed in 2 patients. Frontotemporal zygomatic extradural approach was carried out in 21 patients. The first follow-up visit was on the 3rd month after surgery, and if residual was observed on enhanced MRI, then the patient was followed up every 6 months; otherwise, the patient was followed up every 8-12 months. RESULTS: The length of hospital stay after surgery was 7-13 days (mean 8.5 days). Two tumors originated from the ophthalmic branch, 2 from the maxillary branch, 5 from the mandibular branch and 14 from the gasserian ganglion. Total resection was achieved in 21 of the 23 patients (91.3%) and subtotal resection in the other 2 patients. All the patients were followed up from 3 months to 4 years. Median follow-up time was 19 months. The most common symptom was facial hypoesthesia, occurring in 18 patients. This symptom improved in 10 patients and worsened in 8 patients after surgery. New postoperative facial hypoesthesia was observed in 2 patients. Facial pain was observed in 3 patients and subsided after surgery. Two patients had loss of hearing, this symptom improved in 1 patient and worsened in 1 patient after surgery. Diplopia was observed in 6 patients. In 1 of these 6 patients, diplopia resulted from palsy of the oculomotor nerve. In the other 5 patients, diplopia resulted from palsy of the abducens nerve. This symptom improved postoperatively in all these 6 patients. New postoperative atrophy of the temporalis muscle was observed in 3 patients. There was no operation-related mortality. Tumor recurrence was only found in 1 patient after 24 months and was treated by Gamma knife. CONCLUSIONS: The middle fossa extradural approach may be an ideal option for the resection of trigeminal schwannomas involving the cavernous sinus. This approach produces no further impairment, less complication, and is less likely to injured the trigeminal nerve, abducens nerve, trochlear nerve and internal carotid artery.

[Surveillance of adverse events following immunization in Henan Province, China between 2010-2011].

OBJECTIVE: To analyze the epidemiological features of adverse events following immunization (AEFI) in Henan Province, China and to evaluate the safety of vaccines currently used in Henan. METHODS: The AEFI cases reported in Henan from January 1, 2010 to December 31, 2011 were collected through the China Surveillance System of Information on National Immunization Program. The descriptive method was used for epidemiological analysis. RESULTS: A total of 2415 cases of AEFI were reported in Henan from January 1, 2010 to December 31, 2011, and 1238 (51.26%) of them were found in Zhengzhou, Luoyang, and Jiaozuo cities. The male-to-female ratio was 1.32:1. Seven hundred and ninety-nine (33.08%) of these cases were less than one year old. Measles vaccine and DPT vaccine (against diphtheria, pertussis, and tetanus) were the main causes of AEFI, contributing to 61.24% of cases; the incidence rates of AEFI among people receiving measles and DPT vaccines were 30.3/105 and 5.0/105, respectively. 1528 cases (63.27%) developed AEFI after the first dose of vaccination. Inflammation and allergic symptoms were the predominant adverse effects caused by the top 5 vaccines AEFI-causing vaccines, and the clinical manifestations were significantly different among AEFI cases caused by different vaccines (χ2=304.5, P<0.001). Among the 2415 AEFI cases, 1946 (80.58%) had common adverse reaction, 348 (14.41%) had rare adverse reaction, 98 (4.06%) had coupling disease, 13 (0.51%) had psychogenic reaction, and 10 (0.41%) had reaction for unknown reasons. The prognosis of most AEFI cases was good, with a cure rate as high as 90.64%. CONCLUSIONS: AEFI occurs mostly in young children and after the first dose of vaccination. This should be brought to the attention of vaccination service personnel and the children's parents.

Combination of the Barthel Index at Discharge with GRACE Leads to Improved One-Year Mortality Prediction in Older Patients with Acute Myocardial Infarction.

Purpose: Many older patients with acute myocardial infarction (AMI) have impaired ability for activities of daily living (ADL). Impaired ADL leads to poor prognosis in elderly patients. The Global Registry of Acute Coronary Events (GRACE) score is widely used for risk stratification in AMI patients but does not consider physical performance, which is an important prognosis predictor for older adults. This study assessed whether the Barthel Index (BI) score combine the GRACE score would achieve improved one-year mortality prediction in older AMI patients. Patients and Methods: This single-center retrospective study included 688 AMI patients aged ≥65 years who were divided into an impaired ADL group (BI ≤60, n = 102) and a normal ADL group (BI >60, n = 586) based on BI scores at discharge. The participants were followed up for one year. Cox survival models were constructed for BI score, GRACE score, and BI score combined GRACE score for one-year mortality prediction. Results: Patients had a mean age of 76.29 ± 7.42 years, and 399 were men (58%). A lower BI score was associated with more years of hypertension and diabetes, less revascularization, longer hospital stays, and higher one-year mortality after discharge. Multivariable Cox regression analysis identified BI as a significant risk factor for one-year mortality in older AMI patients (HR 0.977, 95% CI, 0.963-0.992, P = 0.002). BI (0.774, 95% CI: 0.731-0.818) and GRACE (0.758, 95% CI: 0.704-0.812) scores had similar predictive power, but their combination outperformed either score alone (0.810, 95% CI: 0.770-0.851). Conclusion: BI at discharge is a significant risk factor for one-year mortality in older AMI patients, which can be better predicted by the combination of BI and GRACE scores.

Numerical investigation of localization in two-dimensional quasiperiodic mosaic lattice.

A one-dimensional lattice model with mosaic quasiperiodic potential is found to exhibit interesting localization properties, e.g. clear mobility edges (Wanget al2020Phys. Rev. Lett.125196604). We generalize this mosaic quasiperiodic model to a two-dimensional version, and numerically investigate its localization properties: the phase diagram from the fractal dimension of the wavefunction, the statistical and scaling properties of the conductance. Compared with disordered systems, our model shares many common features but also exhibits some different characteristics in the same dimensionality and the same universality class. For example, the sharp peak atg∼0of the critical distribution and the largeglimit of the universal scaling functionßresemble those behaviors of three-dimensional disordered systems.

Quantum transports in two-dimensions with long range hopping.

We investigate the effects of disorder and shielding on quantum transports in a two dimensional system with all-to-all long range hopping. In the weak disorder, cooperative shielding manifests itself as perfect conducting channels identical to those of the short range model, as if the long range hopping does not exist. With increasing disorder, the average and fluctuation of conductance are larger than those in the short range model, since the shielding is effectively broken and therefore long range hopping starts to take effect. Over several orders of disorder strength (until [Formula: see text] times of nearest hopping), although the wavefunctions are not fully extended, they are also robustly prevented from being completely localized into a single site. Each wavefunction has several localization centers around the whole sample, thus leading to a fractal dimension remarkably smaller than 2 and also remarkably larger than 0, exhibiting a hybrid feature of localization and delocalization. The size scaling shows that for sufficiently large size and disorder strength, the conductance tends to saturate to a fixed value with the scaling function [Formula: see text], which is also a marginal phase between the typical metal ([Formula: see text]) and insulating phase ([Formula: see text]). The all-to-all coupling expels one isolated but extended state far out of the band, whose transport is extremely robust against disorder due to absence of backscattering. The bond current picture of this isolated state shows a quantum version of short circuit through long hopping.

Application of thermal alkaline hydrolysis technology to improve the loading and in-vitro release of gallic acid in UiO-66.

The purpose of this study was to treat UiO-66 (University of Oslo 66) under suitable thermal alkaline hydrolysis condition to realize the loading of gallic acid. UiO-66-SH (UiO-66-separated-heating) was obtained by separated heating UiO-66 and 0.2 M KOH aqueous solution to 120 ℃ before mixing for 3 h. The material was in an amorphous state, maintained the octahedron structure and size of UiO-66. UiO-66-SH has better porosity and specific surface area than UiO-66, and had good thermal stability until heated to 1000 ℃. Furthermore, UiO-66-SH had very little influence of the cellular activity of human normal heptical cell line, demonstrating its good biocompatibility. The prepared UiO-66-SH could successfully adsorb gallic acid and control the release of gallic acid in simulated gastric fluid (∼58% vs. âˆ¼ 88% of free gallic acid). This study will be conducive to preparation of appropriate carrier used to load with polyphenolic compounds such as gallic acid.

A case-case study on the effect of primary and booster immunization with China-produced COVID-19 vaccines on prevention of pneumonia and viral load among vaccinated persons infected by Delta and Omicron variants.

Using a three-prefecture, two-variant COVID-19 outbreak in Henan province in January 2022, we evaluated the associations of primary and booster immunization with China-produced COVID-19 vaccines and COVID-19 pneumonia and SARS-CoV-2 viral load among persons infected by Delta or Omicron variant. We obtained demographic, clinical, vaccination, and multiple Ct values of infections ≥3 years of age. Vaccination status was either primary series ≥180 days prior to infection; primary series <180 days prior to infection, or booster dose recipient. We used logistic regression to determine odds ratios (OR) of Delta and Omicron COVID-19 pneumonia by vaccination status. We analysed minimum Ct values by vaccination status, age, and variant. Of 826 eligible cases, 405 were Delta and 421 were Omicron cases; 48.9% of Delta and 19.0% of Omicron cases had COVID-19 pneumonia. Compared with full primary vaccination ≥180 days before infection, the aOR of pneumonia was 0.48 among those completing primary vaccination <180 days and 0.18 among booster recipients among these Delta infections. Among Omicron infections, the corresponding aOR was 0.34 among those completing primary vaccination <180 days. There were too few (ten) Omicron cases among booster dose recipients to calculate a reliable OR. There were no differences in minimum Ct values by vaccination status among the 356 Delta cases or 70 Omicron cases. COVID-19 pneumonia was less common among Omicron cases than Delta cases. Full primary vaccination reduced pneumonia effectively for 6 months; boosting six months after primary vaccination resulted in further reduction. We recommend accelerating the pace of booster dose administration.

Numerical study of disorder on the orbital magnetization in two dimensions.

The modern theory of orbital magnetization (OM) was developed by using Wannier function method, which has a formalism similar with the Berry phase. In this manuscript, we perform a numerical study on the fate of the OM under disorder, by using this method on the Haldane model in two dimensions, which can be tuned between a normal insulator or a Chern insulator at half filling. The effects of increasing disorder on OM for both cases are simulated. Energy renormalization shifts are observed in the weak disorder regime and topologically trivial case, which was predicted by a self-consistent T-matrix approximation. Besides this, two other phenomena can be seen. One is the localization trend of the band orbital magnetization. The other is the remarkable contribution from topological chiral states arising from nonzero Chern number or large value of integrated Berry curvature. If the fermi energy is fixed at the gap center of the clean system, there is an enhancement of |M| at the intermediate disorder, for both cases of normal and Chern insulators, which can be attributed to the disorder induced topological metal state before localization.

Safety and effectiveness of multi-antenna microwave ablation-oriented combined therapy for large hepatocellular carcinoma.

BACKGROUND: In patients with a large, unresectable hepatocellular carcinoma (HCC), the primary recommendation is for transarterial chemoembolization (TACE) but used alone TACE is not typically curative. Combinations of TACE followed in a delayed fashion by single-applicator thermal ablation have also been suboptimal. As an alternative, we investigated the combination of TACE followed within 1-3 days by multi-antenna microwave ablation (MWA) in patients with a large HCC, to determine the feasibility, safety, local control, and short-term survival rates of this approach. METHODS: We retrospectively studied 43 patients with a large HCC (mean diameter, 8.8 cm; SD, 2.8 cm) treated between July 2015 and July 2018, who underwent TACE followed within 3 days by multi-antenna simultaneous MWA. We measured the liver and renal function before and after treatment, recorded complications, used three-dimensional software and imaging to calculate tumor necrosis rates at 1 month after therapy, and calculated overall survival (OS) and progression-free survival (PFS) using the Kaplan-Meier method. RESULTS: Mean follow up was 12.2 (range, 3.5-35.6) months. All patients completed the treatment protocol. At 1 month after combined therapy, tumor necrosis was complete in 16 (37.2%), nearly complete in 19 (44.2%), and partial in 8 (18.6%) patients. The 1- and 2-year OS rates were 64.0% and 46.8%, respectively, with a median OS of 23.0 months; and the 1- and 2-year PFS rates were 19.9% and 4.4%, respectively, with a median PFS of 4.2 months. A transient change in liver function occurred 3 days after MWA but resolved within 1 month. Only two patients had major complications, which were treatable and resolved. CONCLUSION: Multi-antenna MWA-oriented combined therapy is feasible and well tolerated, and it results in satisfactory initial local control and short-term survival in some but not all patients with a large HCC.

Barrier tunneling of the loop-nodal semimetal in the hyperhoneycomb lattice.

We theoretically investigate the barrier tunneling in the 3D model of the hyperhoneycomb lattice, which is a nodal-line semimetal with a Dirac loop at zero energy. In the presence of a rectangular potential, the scattering amplitudes for different injecting states around the nodal loop are calculated, by using analytical treatments of the effective model, as well as numerical simulations of the tight binding model. In the low energy regime, states with remarkable transmissions are only concentrated in a small range around the loop plane. When the momentum of the injecting electron is coplanar with the nodal loop, nearly perfect transmissions can occur for a large range of injecting azimuthal angles if the potential is not high. For higher potential energies, the transmission shows a resonant oscillation with the potential, but still with peaks being perfect transmissions that do not decay with the potential width. These strikingly robust transports of the loop-nodal semimetal can be approximately explained by a momentum dependent Dirac Hamiltonian.

Microsurgical treatment of craniopharyngioma: Experiences on 183 consecutive patients.

This study aimed to summarize the clinical experiences and postoperative effects of microsurgical approaches for craniopharyngioma.A total of 183 craniopharyngioma patients who underwent microsurgical treatment since March 2009 to March 2015 in our hospital were included in current research. Surgical approaches were selected based on preoperative evaluations, including tumor locations, sizes, and growth patterns. Active measurements to manage water-electrolyte disorder and insipidus were taken for postoperative treatments. During the follow-up, patients were monitored for residual or recurrent tumor by postoperative contrast MRI scans done 1 to 3 months after surgery.The used surgical approaches were as follows: frontopterional approach (76 cases), anterior interhemispheric approach (58 cases), transcallosal approach (10 cases), transsphenoidal approach (15 cases), unilateral subfrontal approach (15 cases), and combined approaches (9 cases). Around 124 cases (72.7%) received total tumor resection, 37 patients (20.2%) underwent subtotal resection, and 13 patients (7.1%) underwent partial removal. No significant difference was found on the postoperative complications among the different microsurgical approaches (all, P > .05). A total of 111 cases had an intact pituitary stalk preservation and 26 cases had partially preserved stalks during surgery. Visual improvement was achieved in 54 patients and visual deterioration occurred in 22 cases. Postoperative insipidus appeared in 114 cases and water-electrolyte disorder occurred in 99 cases. The postsurgical follow-up ranged from 3 to 69 months with a mean duration of 27.3 months and 23 patients suffered recurrence.Based on careful preoperative evaluation, microsurgical treatments may be safe and effective approach to improve postoperative outcomes of craniopharyngioma patients.

Treatment Strategies for Intracranial Mirror Aneurysms.

OBJECTIVE: Intracranial mirror aneurysms are clinically rare and uncommonly reported in the literature. Therefore, the present study evaluated a series of mirror aneurysm cases with respect to the clinical features of the patients and the treatment strategies that were used. METHODS: This study retrospectively reviewed and systematically analyzed the clinical features, imaging data, treatment methods, and treatment outcomes of 68 cases of mirror aneurysms (a total of 70 pairs) in patients who were admitted to our department between November 2007 and May 2016. RESULTS: The patient population included 24 male and 44 female patients, with a mean age of 52 years. The mirror aneurysms were primarily located in posterior communicating artery and middle cerebral artery and 65 of the aneurysms were large or giant (≧10 mm). Of the 68 patients, 28 were treated by the clipping or embolization of all aneurysms in one stage, 16 were treated in 2 stages, 16 were treated by treating part of the aneurysms, and 8 were observed. The modified Rankin Scale scores of the 60 patients that were treated indicated that 52 had a good recovery (modified Rankin Scale score ≦2; 86.7%), and 1 patient died. CONCLUSIONS: Treatment strategies for mirror aneurysms should be determined individually according to the location, size, and morphology of the aneurysm, as well as the clinical manifestations of each patient. Furthermore, the responsible ruptured aneurysm should be given treatment priority, whereas the contralateral unruptured aneurysm should be observed or treated in either 1 or 2 stages.

Hydrochloric acid-enhanced radiofrequency ablation for treating a large hepatocellular carcinoma with spontaneous rapture: a case report.

BACKGROUND: A ruptured hepatocellular carcinoma (HCC) is often fatal. In addition to surgery and transarterial embolization, radiofrequency ablation (RFA) might be another option for treating a ruptured HCC. Unfortunately, conventional RFA has a limited ablation zone; as such, it is rarely used to treat ruptured tumors. CASE PRESENTATION: This case was a 60-year-old man who had a large, ruptured HCC in which hydrochloric acid (HCl)-enhanced RFA successfully controlled the bleeding and made the tumor completely necrotic. CONCLUSION: Considering the effectiveness of HCl-enhanced RFA in achieving hemostasis and tumor ablation, it might be a new option for treating large, ruptured HCCs.

Route towards Localization for Quantum Anomalous Hall Systems with Chern Number 2.

The quantum anomalous Hall system with Chern number 2 can be destroyed by sufficiently strong disorder. During its process towards localization, it was found that the electronic states will be directly localized to an Anderson insulator (with Chern number 0), without an intermediate Hall plateau with Chern number 1. Here we investigate the topological origin of this phenomenon, by calculating the band structures and Chern numbers for disordered supercells. We find that on the route towards localization, there exists a hidden state with Chern number 1, but it is too short and too fluctuating to be practically observable. This intermediate state cannot be stabilized even after some "smart design" of the model and this should be a universal phenomena for insulators with high Chern numbers. By performing numerical scaling of conductances, we also plot the renormalization group flows for this transition, with Chern number 1 state as an unstable fixed point. This is distinct from known results, and can be tested by experiments and further theoretical analysis.

Comparison of dual influenza and pneumococcal polysaccharide vaccination with influenza vaccination alone for preventing pneumonia and reducing mortality among the elderly: A meta-analysis.

The purpose of this study was to perform a meta-analysis comparing the effectiveness of influenza vaccination alone versus influenza plus pneumococcal dual vaccination for the prevention of pneumonia and mortality in adults ≥ 65 years of age. Medline, Cochrane, CENTRAL, EMBASE, and Google Scholar databases were searched. Inclusion criteria were: 1) Randomized controlled trials (RCTs), 2-arm prospective studies, or retrospective cohort studies; 2) Patients were ≥ 65 years of age with or without chronic respiratory disease; 3) Patients received the influenza vaccine alone or dual pneumococcal and influenza vaccination; 4) Results included incidence of recurrent respiratory tract infections, length of hospital stay, and overall mortality rate. The outcomes were pneumonia and all-cause mortality rates. Of 142 studies identified in the database searches, 6 were ultimately included in the systematic review, and 5 were included in meta-analysis. The number of patients that received the influenza vaccination alone ranged from 211 to 29,346 (total = 53,107), and the number that received influenza+pneumococcal vaccination ranged from 246 to 72,107 (total = 102,068). Influenza+pneumococcal vaccination was associated with a significantly lower pneumonia rate than influenza vaccination alone (relative risk [RR] = 0.835, 95% confidence interval [CI]: 0.718-0.971, P = 0.019), and with a significantly lower all-cause mortality rate than influenza vaccination alone (relative risk [RR] = 0.771, 95% confidence interval [CI]: 0.707-0.842, P = 0.001). In conclusion, the results of this study support concomitant pneumococcal and influenza vaccination of the elderly as a dual vaccination strategy is associated with lower pneumonia and all-cause mortality rates.

Topological quantum transitions in a two-band Chern insulator with n = 2.

Based on a two-band Chern insulator with Chern number n = 2, we study the transport properties and the topological phase transition induced by either an external magnetic field or disorder. In this paper, a characteristic topological phase transition from n = 2 to n = 0, which is in sharp contrast to the plateau-plateau transition in the integer quantum Hall effect, is observed. This unique feature of the phase transition should be ascribed to the minimal two-band feature of this high Chern insulator. We prove this result by studying the transport properties of many different geometrical structures and the evolution of the Chern number in the presence of magnetic fields and strong disorder.

Three-dimensional topological insulator in a magnetic field: chiral side surface states and quantized Hall conductance.

Low energy excitation of surface states of a three-dimensional topological insulator (3DTI) can be described by Dirac fermions. By using a tight-binding model, the transport properties of the surface states in a uniform magnetic field are investigated. It is found that chiral surface states parallel to the magnetic field are responsible for the quantized Hall (QH) conductance (2n + 1)e²/h multiplied by the number of Dirac cones. Due to the two-dimensional nature of the surface states, the robustness of the QH conductance against impurity scattering is determined by the oddness and evenness of the Dirac cone number. An experimental setup for transport measurement is proposed.