[en] The paper presents the electrical properties of a newly designed single delta-doped InGaP/InGaAs/GaAs pseudomorphic high electron mobility transistor (HEMT) with n⁺-GaAs/p⁺-InGaP/n-InGaP camel-like gate structure. For a 1x100 μm² device, the experimental results exhibit an extrinsic transconductance of 85 mS mm^-1 and a saturation current density of 425 mA mm^-1. Significantly, due to the p-n depletion from p⁺-InGaP gate to channel region and the presence of considerable conduction band discontinuity at InGaP/InGaAs heterostructure, the gate-to-drain turn-on voltage is larger than 1.7 V. In addition, an extremely broad gate voltage swing larger than 3 V with above 80% maximum g_m is obtained. The unit current cutoff frequency f_T and maximum oscillation frequency f_max are up to 18 and 30 GHz, respectively

No abstract available

[en] Radiocarbon (14C) is a powerful tracer of the global carbon cycle that is commonly used to assess carbon cycling rates in various Earth system reservoirs and as a benchmark to assess model performance. Therefore, it has been recommended that Earth System Models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 report predicted radiocarbon values for relevant carbon pools. However, a detailed representation of radiocarbon dynamics may be an impractical burden on model developers. Here, we present an alternative approach to compute radiocarbon values from the numerical output of an ESM that does not explicitly represent these dynamics. The approach requires computed 12C stocks and fluxes among all carbon pools for a particular simulation of the model. From this output, a time‐dependent linear compartmental system is computed with its respective state‐transition matrix. Using transient atmospheric 14C values as inputs, the state‐transition matrix is then applied to compute radiocarbon values for each pool, the average value for the entire system, and component fluxes. We demonstrate the approach with ELMv1‐ECA, the land component of an ESM model that explicitly represents 12C, and 14C in 7 soil pools and 10 vertical layers. Results from our proposed method are highly accurate (relative error <0.01%) compared with the ELMv1‐ECA 12C and 14C predictions, demonstrating the potential to use this approach in CMIP6 and other model simulations that do not explicitly represent 14C.

[en] Nd-Fe-B magnets have outstanding magnetic properties, but their corrosion resistance is poor because the rare-earth-rich phases in them are easily oxidized. In this article, we report an investigation of the corrosion behaviors of sintered Nd-Fe-B magnets with varied compositions in different corrosion conditions. The weight losses of the magnets after corrosion testing were measured after brushing off the corrosion products. The magnetic flux losses of the magnets were measured using a fluxmeter. A scanning electron microscope equipped with an energy dispersive x-ray analysis system was employed to observe the corrosion morphology. It was found that the humid-heat resistance of the magnets was obviously improved by partially substituting Dy for Nd and adding minor Co. The corrosion products and morphologies of Nd-Fe-B magnets for the autoclave test were different from those for the constant humid-heat test. The corrosion rates of the magnets for the former were much slower than for the latter; this is probably because the high-pressure steam led to an oxygen-deficient atmosphere, and the liquid film on the surface of the magnet specimens hindered the diffusion of oxygen into the bulk for the autoclave test.

[en] An aperiodic optical superlattice is designed. The designing method is universal and can be applied to all frequency conversion processes by using the coupling of quasiphase matching, without any limitations to special materials and to given fundamental wavelengths. Copyright 2001 American Institute of Physics

[en] Objectives: To investigate the clinical distribution and drug resistance of Klebsiella pneumoniae pulmonary infection in patients with hypertensive intracerebral hemorrhage after minimally invasive surgery. Methods: A total of 658 patients with hypertensive intracerebral hemorrhage who underwent minimally invasive surgery admitted to the intensive care unit (ICU) and the Department of Neurology of Affiliated Hospital of Hebei University from January 2015 to January 2020 were enrolled and divided into two groups: the observation group and the control group. Three hundred and thirty-three cases with postoperative pulmonary infection were included into the observation group, and 325 cases without postoperative pulmonary infection were divided into the control group. The intubation time, neurological deficiency score and Glasgow coma scale (GCS) of the two groups were analyzed and compared. Automatic microbial identification system was utilized to isolate bacteria from patients in the observation group, identify Klebsiella pneumoniae, and analyze Klebsiella pneumoniae infection, clinical department distribution, and age distribution. The KirbyBauer method was adopted to carry out the drug susceptibility test of Klebsiella pneumoniae infection. Results: The intubation time and neurological deficiency score of patients with hypertensive cerebral hemorrhage in the observation group were significantly higher than those in the control group (p<0.05), while the GCS score was significantly lower than that in the control group (p<0.05). A total of 403 strains of pathogenic bacteria were isolated from 325 patients in the observation group, of which 52 strains of Klebsiella pneumoniae were detected in 52 patients with postoperative pulmonary infection, accounting for 12.90%. The detection rates of Klebsiella pneumoniae in ICU and neurology department were 53.85% and 46.15%, respectively. Klebsiella pneumoniae had the highest detection rate (40.38%) in people aged 70 years and above. Moreover, fifty-two strains of Klebsiella pneumoniae showed low drug resistance rate (<20%) to cefoperazone/sulbactam, piperacillin/tazobactam, cefoxitin, imipenem, meropenem, amikacin, ciprofloxacin, and levofloxacin. Conclusion: For patients with hypertensive cerebral hemorrhage who have pulmonary infection after minimally invasive surgery, risk factors causing infection should be identified in time, their Klebsiella pneumoniae infection should be correctly monitored, and antibiotics should be taken rationally to effectively promote the elimination of brain edema in patients and protect the cranial nerve function of patients. (author)

[en] We give a formulation of high-energy scattering via path integrals. This nonperturbative formulation allows the approximate treatment of both fixed-angle scattering as well as small-angle scattering. The only approximation made is replacing the summation of the paths of an external particle by the contribution of the classical path: a straight line for small-angle scattering and two straight lines joined at the origin at an angle for fixed-angle scattering. In this way, the scattering amplitude is factorized into a product of two amplitudes: the amplitude for the interaction between the external particles and the amplitude for vacuum-to-vacuum transition in the presence of the external fields produced classically by the external particles. We show that all of the exactly calculable factors (the eikonal formula, the Sudakov form factor, and the energy-dependent factor of multiphoton exchange for fixed-angle scattering) belong to the first amplitude and are easily produced by a semiclassical treatment. The second amplitude is fully quantum mechanical, and no justified approximation has been found. In the case of small-angle scattering, we deduce, with this formulation, the principle of the equivalence of phase space. For the case of fixed-angle scattering, we find that there are three time scales: ß^-₁, lambda, and ß, where ß is the incident c.m. energy and lambda is the photon mass

[en] Quenching of melts of Bi-Sr-Ca-Cu oxides has been found to produce amorphous materials of extremely high density from which favorable superconductors of close to 100% theoretical density can be prepared by proper annealing conditions. The addition of Pb, which partially replaces Bi, has been found to be favorable in obtaining high T_c phase in this system compared to non-substituted counterparts. In connection with this work, a preparation of superconducting thick films of -- 20 μm in thickness by in-situ melting directly on substrates is discussed

[en] Blue honeysuckle is a shrub species widely distributed in the northern regions of the world, the nutritious fruits of which have high economic value and are considered to have beneficial health effects. To gain a better understanding of the genetic background of blue honeysuckle, we employed sequence-related amplified polymorphism (SRAP) markers to analyse the genetic diversity of 58 blue honeysuckle germplasms, which are naturally distributed in China, Russia, and Japan. A total of 20 SRAP primer pairs showing clear polymorphisms, screened from 90 assessed primer pairs, were used to analyse genetic relationships among the 58 blue honeysuckle germplasms. The results revealed that the 20 primer pairs amplified 172 bands, among which, 143 bands were polymorphic, with a polymorphic rate of 83.1%. Each primer pair yielded between five and 12 bands, with an average band number of 8.6. Unweighted pair-group method with arithmetic (UPGMA) cluster analysis of the SRAP marker data revealed that genetic similarity coefficients of the 58 germplasms ranged from 0.68 to 0.95. The germplasms were divided into seven groups with a genetic similarity coefficient 0.74, with germplasms from China being characterised by greater differences than those from Russia. Wild genotypes from Mount Changbai and the Great Khingan mountains were classified into a single group, indicating that cultivar classification has been based on genotype composition. In general, blue honeysuckle has a high genetic diversity, which will provide a valuable basis for future breeding. (author)

[en] The first man-loading high temperature superconducting (HTS) magnetic levitation (Maglev) test vehicle in the world has normally operated over one year after its birth on December 31, 2000. Heretofore over 23 000 passengers have taken the vehicle, and it operates very well from first running to now. The HTS Maglev vehicle is over guideway, which consists of two parallel permanent magnetic tracks. The levitation force of the entire Maglev vehicle is measured. Three times measurement results on December 24, 2000, July 1, 2001, and December 24, 2001 are reported respectively, it will be seen from this that the levitation forces do not change nearly after long running. Total levitation force of entire vehicle is 1050 kg at the 8 mm net levitation gap, which the gap between the bottom of liquid nitrogen vessels and guideway face. A measuring equipment of the guidance force of the entire Maglev vehicle is designed and manufactured. The guidance force of the vehicle is obtained by the equipment