There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

An introduction to heat transfer

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

The stability of two-dimensional (2D) layers and membranes is subject of a long standing theoretical debate. According to the so called Mermin-Wagner theorem, long wavelength fluctuations destroy the long-range order for 2D crystals. Similarly, 2D membranes embedded in a 3D space have a tendency to be crumpled. These dangerous fluctuations can, however, be suppressed by anharmonic coupling between bending and stretching modes making that a two-dimensional membrane can exist but should present strong height fluctuations. The discovery of graphene, the first truly 2D crystal and the recent experimental observation of ripples in freely hanging graphene makes these issues especially important. Beside the academic interest, understanding the mechanisms of stability of graphene is crucial for understanding electronic transport in this material that is attracting so much interest for its unusual Dirac spectrum and electronic properties. Here we address the nature of these height fluctuations by means of straightforward atomistic Monte Carlo simulations based on a very accurate many-body interatomic potential for carbon. We find that ripples spontaneously appear due to thermal fluctuations with a size distribution peaked around 70 \AA which is compatible with experimental findings (50-100 \AA) but not with the current understanding of stability of flexible membranes. This unexpected result seems to be due to the multiplicity of chemical bonding in carbon.

Intrinsic ripples in graphene

Magnetocaloric effect: From materials research to refrigeration devices

Objective Although chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary disease (CTEPD) are known to be accompanied by symptoms associated with sleep-disordered breathing (SDB) and nocturnal hypoxemia, the sex-specific differences of SDB and nocturnal hypoxemia in patients with CTEPH and CTEPD remain unknown. Methods Between July 2020 and August 2022, data were retrieved from 57 males and 63 female patients with CTEPH and CTEPD who underwent sleep study at Shanghai Pulmonary Hospital. Nocturnal mean SpO2 (mean SpO2) < 90% was defined as nocturnal hypoxemia. Logistic and linear regression analysis was performed to assess the predictive value of sleep study indices to hemodynamic parameters. Receiver operating characteristic (ROC) curve was applied to analyze the specific parameters to predict the risk of CTEPH. Results SDB was similarly present in males and females, and both sexes predominantly had obstructive sleep apnea (OSA); more women were diagnosed with nocturnal hypoxemia (32 vs. 7%, p = 0.002). SaO2 was negatively associated with mean pulmonary arterial pressure (mPAP) in men (p < 0.001), whereas the ratio of nocturnal SpO2 < 90% of the total monitoring time (T90%) was positively correlated with mPAP. Mean SpO2 was an independent predictor for pulmonary vascular resistance and cardiac output in women (p = 0.001, p < 0.001, p = 0.001, respectively). T90%, SaO2, and minimal SpO2 were combined to develop a new composite parameter: hypoxemia scoring index (HSI). ROC curve analysis indicated that HSI levels of 0.55 could discriminate CTEPH from CTEPD with a sensitivity of 92.3% and specificity of 87.5% in female patients (an area under the curve, 0.937; 95% CI: 0.879–0.995, p < 0.001). Conclusion Sex-specific nocturnal hypoxemia was present in patients with CTEPH or CTEPD. In female patients, the HSI showed high capacity for predicting the risk of CTEPH. Clinical trials registration Registry: chictr.org.cn; Identifier: ChiCTR-DDD-16009406.

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Sex-specific differences in sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary hypertension and chronic thromboembolic pulmonary disease

A continuous physics based analytic model of undoped (or lightly doped) body MOSFETs has been derived in this paper by incorporating the solution of the Poisson equation into Pao-Sah integrated current equation using SPP approach. The closed form solutions of band bending and the inversion charge as a function of gate voltage and channel voltage were first derived from the combination of Gauss's law with the Poisson equation. Then, a continuous non-charge-sheet-based analytical model is developed for the undoped body MOSFETs.

A physics based analytical model of undoped body MOSFETs

This work presents a gate-all-around tunneling FET based on SiO2 core and Si shell structure (GAA-SOI-TFET) and demonstrates its performance characteristics via the numerical simulation method. The 3-D T-CAD numerical simulations demonstrate that this new device has steep subthreshold swing (<60mV/dec), suppressed drain-induced barrier lowering, and enhanced Ion/Ioff ratio up to 10 9 orders of magnitude. It is worth noting that Ion begins to increase when SiO2 core radius exceeds a specified value (~4nm) while influence of gate oxide thickness on the device performance being an important factor.

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Numerical study on gate-All-Around tunneling FET with SiO2 core and Si shell structure

1 The Key Laboratory of Integrated Microsystems, School of Computer & Information Engineering, Peking University Shenzhen Graduate School, Shenzhen 518055, P. R. China 2 Peking University Shenzhen SOC Key Laboratory, PKU-HKUST Shenzhen Institute, Shenzhen 518057, P.R.China 3 Department of ECE, Hongkong University of Science and Technology, Bay, Kowloon, Hong Kong, P. R. China Abstract-In this paper we provide an insight into the drain current model for long-channel MOSFET devices. A new method to perform the integral of the rigorous Pao-Sah dual integral current is derived. From it, we demonstrate the error of the traditional charge sheet models in predicting the drain current compared with Pao-Sah’s dual integral model, also provide the reason that Brews’ charge sheet model fails to pass the self consistency tests reported previously. Three charge-sheet approximation models are tested in order to find a simple yet accurate drain current model for surface potential-based compact models. Keywords--MOSFET models, charge-sheet approximation, drain current model

Comparison and insight into long-channel MOSFET drain current models

A numerical method is proposed to simulate the corresponding terahertz photoresponse which is induced by radiations between source-and-gate and gate-and-drain electrodes in field effect transistors. Simulations illustrate that the response of terahertz radiation in field effect transistor depends on the gate bias. The response contains contributions of different polarities which induced by radiations between 'source and gate electrodes' and 'gate and drain electrodes' respectively. The simulation matches well with the existing theory quantitatively. The proposed method is also used to study the response in resonant region by changing some parameters of field effect transistors (FET). The results illustrate that it is a useful tool in THz detector design and optimization.

Jin He

Papers

Sex-specific differences in sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary hypertension and chronic thromboembolic pulmonary disease

A physics based analytical model of undoped body MOSFETs

Numerical study on gate-All-Around tunneling FET with SiO2 core and Si shell structure

Comparison and insight into long-channel MOSFET drain current models

Numerical Simulation on the Voltage Response of Field Effect Transistor by Focused Terahertz Radiation