Light-induced half-quantized Hall effect and axion insulator

Motivated by the recent experimental realization of the half-quantized Hall effect phase in a three-dimensional (3D) semi-magnetic topological insulator [M. Mogi et al., Nature Physics 18, 390 (2022)], we propose a scheme for realizing the half-quantized Hall effect and axion insulator in experimentally mature 3D topological insulator heterostructures. Our approach involves optically pumping and/or magnetically doping the topological insulator surface, such as to break time reversal and gap out the Dirac cones. By toggling between left and right circularly polarized optical pumping, the sign of the half-integer Hall conductance from each of the surface Dirac cones can be controlled, such as to yield half-quantized ($0+1/2$), axion ($-1/2+1/2=0$), and Chern ($1/2+1/2=1$) insulator phases. We substantiate our results based on detailed band structure and Berry curvature numerics on the Floquet Hamiltonian in the high-frequency limit. Our paper showcases how topological phases can be obtained through mature experimental approaches such as magnetic layer doping and circularly polarized laser pumping and opens up potential device applications such as a polarization chirality-controlled topological transistor.Comment: 24 pages, 11 figures, update references, published versio

Tianditu: China's first official online mapping service

Tianditu is China’s first state-sponsored web mapping service. Beijing considers Tianditu part and parcel of its burgeoning endeavor to build a ‘digital China’. The Chinese state created Tianditu to regain some of the ground lost when its monopoly on geographic information was effectively broken. This effort goes hand in hand with Beijing’s intention to compete with and shrink the space occupied by Google mapping services (Google Maps, Google Earth, etc.). Although Tianditu does bestow a certain degree of power on civilian users to interact with and explore geographic data, for political and social reasons the Chinese state tightly controls Tianditu. It is a tool that the regime uses to maintain political power and push ideologies it supports. This type of top-down reinforcement of static geographic knowledge is a far cry from the concept of civilian empowerment as understood in liberal democracies

Flow Control by Slot Position and Noise Baffle in a Self-Recirculation Casing Treatment on an Axial Fan-Rotor

To address the situations where the casing treatment needs to be used to stabilize axial compressors through strong recirculation, this paper initiated a CFD study to investigate how the flow could be suitably controlled in the casing treatment to minimize the efficiency penalty and increase the flow range. A counter-swirl self-recirculation casing treatment was first designed on a low speed axial fan rotor as a baseline case. Then three different slot positions and the influence of including the noise baffle were numerically studied. Based on the understanding of their coeffects, the shorter noise baffle was considered and it was found that the highest efficiency was achieved in the case of the upstream slot when the length of baffle was suitably adjusted to balance the incoming flow and recirculation. The largest flow range was achieved by locating the slot at the most downstream position and using a 50% length baffle since it suitably controlled the recirculating flow and relieved the separation at the low-span region. An optimization study showed that the optimum length of the baffle for efficiency was always larger than for the flow range. Both of the two optimum values reduce as the slot moves downstream

Boron Nitride Nanotube Films Grown From Boron Ink Painting

The growth of nanotube films on various substrates and surfaces is vital for applications in nanoscale functional devices. We report a simple and versatile boron (B) ink painting method that enables high-density boron nitride nanotube (BNNT) films with any desired pattern to be grown on, and firmly attached to, different surfaces. In the method, special B ink is first painted, sprayed or inkjet printed at desired location with required pattern, and then the ink layer is annealed in a nitrogen-containing atmosphere to form BNNT film. The B ink is a liquid mixture of ball-milled B particles, metal nitrate and ethanol. This is the first method capable of growing BNNTs on complex non-flat surfaces, which greatly broadens the potential application of BNNTs. For example, it is demonstrated that a BNNT coated steel mesh can separate water and oil on a microliter scale; a needle given an internal BNNT coating could greatly enhance microfluidic transport; and a coated screw could be used to minimize wear at the interface.Comment: 10 pages, 6 figure

Safety and efficacy of etomidate and propofol anesthesia in elderly patients undergoing gastroscopy: A double-blind randomized clinical study

The aim of the present study is to compare the safety, efficacy and cost effectiveness of anesthetic regimens by compound, using etomidate and propofol in elderly patients undergoing gastroscopy. A total of 200 volunteers (65–79 years of age) scheduled for gastroscopy under anesthesia were randomly divided into the following groups: P, propofol (1.5–2.0 mg/kg); E, etomidate (0.15-0.2 mg/kg); P+E, propofol (0.75–1 mg/kg) followed by etomidate (0.075-0.1 mg/kg); and E+P, etomidate (0.075-0.01 mg/kg) followed by propofol (0.75–1 mg/kg). Vital signs and bispectral index were monitored at different time points. Complications, induction and examination time, anesthesia duration, and recovery and discharge time were recorded. At the end of the procedure, the satisfaction of patients, endoscopists and the anesthetist were evaluated. The recovery (6.1±1.2 h) and discharge times (24.8±2.8 h) in group E were significantly longer compared with groups P, P+E and E+P (P<0.05). The occurrence of injection pain in group P+E was significantly higher compared with the other three groups (P<0.05). In addition, the incidence of myoclonus and post-operative nausea and vomiting were significantly higher in group P+E compared with the other three groups (P<0.05). There was no statistical difference among the four groups with regards to the patients' immediate, post-procedure satisfaction (P>0.05). Furthermore, there was no difference in the satisfaction of anesthesia, as evaluated by the anesthetist and endoscopist, among the four groups (P>0.05). The present study demonstrates that anesthesia for gastroscopy in elderly patients can be safely and effectively accomplished using a drug regimen that combines propofol with etomidate. The combined use of propofol and etomidate has unique characteristics which improve hemodynamic stability, cause minimal respiratory depression and less side effects, provide rapid return to full activity and result in high levels of satisfaction

Life table of Cochlochila bullita stål (hemiptera: tingidae) on Orthosiphon aristatus (blume) miq. and Ocimum basilicum l. in laboratory conditions

Ocimum tingid, Cochlochila bullita Stål (Hemiptera: Tingidae) is a pest of Lamiaceae plants such as basil, tulsi and coleus. It is now being recorded in Malaysia as a pest of the cat’s whiskers plant, Orthosiphon aristatus (Blume) Miq. Nevertheless, apart from its brief biological description, no other information is available. The life table of this pest was studied in laboratory conditions. Development time for C. bullita feeding on O. aristatus was 23.3 ± 0.9 days, which was found to be similar to those feeding on Ocimum basilicum (22.8 ± 0.3 days). Although C. bullita posts a higher mortality rate on O. aristatus than on O.basilicum (52% vs. 37%), the adult longevity of the bugs that feed on O. aristatus (♀: 33.9; ♂: 38.2 days) was found to be significantly higher than those bugs that feed on O.basilicum (♀: 27.2; ♂: 26.0 days). The pre-ovipostion, ovispostion and fecundity of C. bullita were also different between the host plants. The net reproductive rates (R0), finite rate of increase (λ) and intrinsic rate of increase (r) were also higher on O. aristatus (10.7504, 1.0690 and 0.0667), although there was an increased in immature survival on O. basilicum (6.0287, 1.0556 and 0.0541). Therefore, it is concluded that O. aristatus is as good as O. basilicum, or the population growth of C. bullita is more favoured as compared to O. basilicum