99 results on '"Jizhou He"'
Search Results
2. Diagnosis and Management of Pseudoblepharoptosis in Eastern Asians: A Commonly Observed But Easily Overlooked Type of Blepharoptosis
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Xianyu Zhou, Jizhou He, Jun Yang, and Fei Liu
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Otorhinolaryngology ,Surgery ,General Medicine - Published
- 2022
3. Concentrated Ultrasound-Processed Fat (CUPF): More than a Mechanically Emulsified Graft
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Jizhou He, Fang-zhou Chen, Yixiang Zhang, Poh-ching Tan, Qingfeng Li, and Chen Cheng
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Surgery - Published
- 2023
4. A three-terminal heat engine based on resonant-tunneling multi-level quantum dots
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Xing Liu, JingZhu Gao, and Jizhou He
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Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
5. Performance of Quantum Heat Engines Enhanced by Adiabatic Deformation of Trapping Potential
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Yang Xiao, Kai Li, Jizhou He, and Jianhui Wang
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quantum Otto engine ,adiabatic deformation ,power ,efficiency ,fluctuations ,General Physics and Astronomy - Abstract
We present a quantum Otto engine model alternatively driven by a hot and a cold heat reservoir and consisting of two isochoric and two adiabatic strokes, where the adiabatic expansion or compression is realized by adiabatically changing the shape of the potential. Here, we show that such an adiabatic deformation may alter operation mode and enhance machine performance by increasing output work and efficiency, even with the advantage of decreasing work fluctuations. If the heat engine in the sudden limit operates under maximal power by optimizing the control parameter, the efficiency shows certain universal behavior, η*=ηC/2+ηC2/8+O(ηC3), where ηC=1−βhr/βcr is the Carnot efficiency, with βhr(βcr) being the inverse temperature of the hot (cold) reservoir. However, such efficiency under maximal power can be produced by our machine model in the regimes where the machine without adiabatic deformation can only operate as a heater or a refrigerator.
- Published
- 2023
6. Performance optimization on finite-time quantum Carnot engines and refrigerators based on spin-1/2 systems driven by a squeezed reservoir
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Haoguang Liu, Jizhou He, and Jianhui Wang
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General Physics and Astronomy - Abstract
We investigate the finite-time performance of a quantum endoreversible Carnot engine cycle and its inverse operation — Carnot refrigeration cycle, employing a spin-1/2 system as the working substance. The thermal machine is alternatively driven by a hot boson bath of inverse temperature β h and a cold boson bath at inverse temperature β c (>β h). While for the engine model the hot bath is constructed to be squeezed, in the refrigeration cycle the cold bath is established to be squeezed, with squeezing parameter r. We obtain the analytical expressions for both efficiency and power in heat engines and for coefficient of performance and cooling rate in refrigerators. We find that, in the high-temperature limit, the efficiency at maximum power is bounded by the analytical value η + = 1 − sech ( 2 r ) ( 1 − η C ) , and the coefficient of performance at the maximum figure of merit is limited by ε + = sech ( 2 r ) ( 1 + ε C ) sech ( 2 r ) ( 1 + ε C ) − ε C − 1 , where η C = 1 – β h/β c and ε C = β h/(β c – β h) are the respective Carnot values of the engines and refrigerators. These analytical results are identical to those obtained from the Carnot engines based on harmonic systems, indicating that the efficiency at maximum power and coefficient at maximum figure of merit are independent of the working substance.
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- 2023
7. Effective Inhibition of Phase Segregation in Wide‐Bandgap Perovskites with Alkali Halides Additives to Improve the Stability of Solar Cells
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Xin Meng, Jianan Wang, Haixin Wang, Mengjie Li, Derun Sun, Xiaodong Hu, Jizhou He, Peng Yu, Jing Zhou, Rui Chen, Fumeng Ren, Sanwan Liu, Shasha Zhang, Yiqiang Zhang, Zhiguo Zhao, Zonghao Liu, and Wei Chen
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Energy Engineering and Power Technology ,Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2023
8. Angiogenesis modulation-mediated inhibitory effects of tacrolimus on hypertrophic scar formation
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Yirui, Shen, Rui, Jin, Xiao, Liang, Zhizhong, Deng, Jizhou, He, Yi, Ding, Feixue, Ding, Lin, Lu, Fei, Liu, and Jun, Yang
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Vascular Endothelial Growth Factor A ,Cicatrix, Hypertrophic ,Neovascularization, Pathologic ,Animals ,Humans ,Endothelial Cells ,Angiogenesis Inducing Agents ,Rabbits ,Cell Biology ,Fibroblasts ,Cardiology and Cardiovascular Medicine ,Biochemistry ,Tacrolimus - Abstract
Hypertrophic scar (HS) is a fibroproliferative disorder that causes cosmetic as well as functional problems; however, to our knowledge, there is no satisfactory treatment for HS to date. Previous studies have indicated that angiogenesis plays a crucial role in HS formation; therefore, anti-angiogenetic therapies are considered effective in improving HS. Although tacrolimus (TAC) has been proven effective in preventing HS formation in vivo and in vitro, its underlying mechanism remains controversial and ambiguous. Because of its anti-angiogenic effects in other diseases, we aimed to determine whether TAC reduces HS by suppressing angiogenesis. Using a rabbit ear HS model that we developed, HS was treated once a week with normal saline, dimethyl sulfoxide, or TAC for 3 weeks. Histological evaluation indicated that TAC significantly reduced collagen deposition and microvessel density in scar tissues. Moreover, immunofluorescence staining for CD31 and vascular endothelial growth factor (VEGF)-A revealed that TAC significantly inhibited HS angiogenesis. In vitro analysis showed that TAC inhibited endothelial cell migration and tubulogenesis as well as the viability and proliferation of human umbilical vascular endothelial cells (HUVECs) and HS fibroblasts (HSFBs). Furthermore, TAC significantly downregulated the expression of the human angiogenetic factors VEGF-A, FGF-2, PDGF-β, and TGF-β1 in HUVECs and HSFBs. Additionally, TAC-mediated inhibition of angiogenesis decreased the gene expression of crucial fibrotic markers, including α- smooth muscle actin and collagens 1 and 3, in HSFBs. This is the first study to demonstrate the inhibitory effects of TAC on HS formation mediated by a mechanism involving the suppression of scar angiogenesis.
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- 2023
9. Rejuvenation of Facial Skin by Transplantation of the Autologous Stromal Vascular Fraction Isolated Using a New Type of Clinical-Grade Collagenase
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Jiaqi Qin, Bin Fang, Jizhou He, Chen Cheng, Jia Zhou, Shuangbai Zhou, Rulin Huang, Poh-ching Tan, Tianyu Zhang, Taoran Jiang, Wenhui Liu, Hairong Wang, Yun Xie, and Qingfeng Li
- Abstract
OBJECTIVE The purpose of this study was to detect the yield, activity and safety of the stromal vascular fraction (SVF) isolated by a new clinical-grade collagenase with a specific process and to validate the efficacy of the method. MATERIALS AND METHODS For the in vitro study, adipose tissue specimens were obtained from women undergoing elective liposuction (n = 5). The SVF was isolated by new clinical-grade collagenase for the experimental group and research-grade collagenase NB4 for the control group. The surface markers of the SVFs isolated by the two collagenases were detected by flow cytometry. The yield, activity and morphology of the SVFs were compared, together with their proliferation, migration and differentiation. Furthermore, we conducted a clinical trial to evaluate the improvement of skin texture after transplantation of autologous SVF isolated by clinical-grade collagenase. RESULTS There were no statistically significant differences in the yield, viability or morphology of the SVFs isolated by the new collagenase and collagenase NB4. Adipose tissue-derived mesenchymal stem cells (ASCs) surface marker expression was consistent between the two products. The differentiation potential of the cells was not different, which was consistent with previously published results. The SVF isolated by the new collagenase had a higher proliferation and migration. After administration of autologous SVF isolated by the new collagenase, the VISIA score improved significantly with regard to wrinkle scores and texture scores. CONCLUSION We concluded that this new type of clinical-grade collagenase can replace current research-grade products without any negative effect on the yield or function of the SVF, which can be applied to antiaging and rejuvenation of facial skin.
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- 2022
10. Recent Advances in the Combined Elevated Temperature, Humidity, and Light Stability of Perovskite Solar Cells
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Jing Zhou, You Gao, Yongyan Pan, Fumeng Ren, Rui Chen, Xin Meng, Derun Sun, Jizhou He, Zonghao Liu, and Wei Chen
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Energy Engineering and Power Technology ,Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
11. Power statistics of Otto heat engines with the Mpemba effect
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Jie Lin, Kai Li, Jizhou He, Jie Ren, and Jianhui Wang
- Abstract
The Mpemba effect is a counterintuitive relaxation phenomenon whereby a system with a higher initial temperature may cool down to the thermal state faster than an identical system that was initially prepared at a lower temperature. Here, we investigate heat and work in a Markovian state transition system with cyclic switching hot-cold temperatures, which operates as an Otto heat engine working in long but finite time, either with or without the Mpemba effect. Under the condition of the periodic steady state having been reached, the time durations of the heating and cooling relaxation processes are determined by exploring a distance-from-equilibrium equivalent to the Kullback-Leibler divergence. We then numerically evaluate and compare the averages and variances of both the work and the power output of two scenarios with and without the Mpemba effect. The results show that the Markovian Mpemba effect can enhance the machine performance by significantly increasing the power output for a given efficiency without sacrificing the stability.
- Published
- 2021
12. A Novel Model for Cutaneous Wound Healing and Scarring in the Rat
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Shuang-Bai Zhou, Jizhou He, Sizheng Zhou, Qingfeng Li, Guo-You Zhang, and Wang Wenjin
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Tail ,Pathology ,medicine.medical_specialty ,Contraction (grammar) ,Cicatrix, Hypertrophic ,Scars ,030230 surgery ,Rats, Sprague-Dawley ,03 medical and health sciences ,Hypertrophic scar ,0302 clinical medicine ,Stretched scar ,medicine ,Animals ,Humans ,Wound Healing ,integumentary system ,business.industry ,Histology ,Dermis ,medicine.disease ,Rats ,Disease Models, Animal ,030220 oncology & carcinogenesis ,Immunohistochemistry ,Surgery ,Collagen ,Stress, Mechanical ,Cutaneous wound ,medicine.symptom ,Wound healing ,business - Abstract
BACKGROUND Current rodent models of wound healing and scarring are flawed because of rapid wound contraction and inconspicuous scarring after healing, which is not closely parallel to the physiologic process in humans. This study aimed to establish a novel model of wound healing and scarring in rats. METHODS Excisional wounds were generated in rat tail or dorsal skin and histologic changes and wound contraction were assessed 2, 10, and 16 days after injury. After healing, rat tail scar was investigated for 24 consecutive weeks by histologic and immunohistochemical staining. Finally, a stretched scar model was generated in rat tail with high or low strain after reepithelialization to mimic human hypertrophic scars. The tail hypertrophic scars were analyzed by histology, immunohistochemical staining, and mRNA quantification 0, 2, 6, 12, and 24 weeks after stretching. RESULTS Compared with the dorsal wounds, a larger dermal gap percentage (p < 0.05) and more pronounced granulation were found in rat tail wounds. Tail scars remained conspicuous and underwent maturation over 24 weeks after wound healing. In addition, high mechanical strain induced significantly increased scar area (p < 0.01), scar height (p < 0.05), vessel density (p < 0.01) and hypertrophic scar-related molecule expression, and distorted collagen arrangement in rat tail scars. CONCLUSIONS The rat tail model exhibits minor wound contraction and biological features analogous to both normotrophic and hypertrophic scar in humans when generated with or without stretching, respectively. It is a promising new model for studies of both cutaneous wound healing and scarring.
- Published
- 2019
13. Optimized finite-time performance of endoreversible quantum Carnot machine working with a squeezed bath
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Haoguang Liu, Jizhou He, and Jianhui Wang
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General Physics and Astronomy - Abstract
We consider a quantum endoreversible Carnot engine cycle and its inverse operation–Carnot refrigeration cycle, working between a hot bath of inverse temperature [Formula: see text] and a cold bath at inverse temperature [Formula: see text]. For the engine model, the hot bath is constructed to be squeezed, whereas for the refrigeration cycle, the cold bath is set to be squeezed. In the high-temperature limit, we analyze efficiency at maximum power and coefficient of performance at maximum figure of merit, revealing the effects of the times allocated to two thermal-contact and two adiabatic processes on the machine performance. We show that, when the total time spent along the two adiabatic processes is negligible, the efficiency at maximum power reaches its upper bound, which can be analytically expressed in terms of squeezing parameter [Formula: see text]: [Formula: see text], with the Carnot efficiency [Formula: see text] and the coefficient of performance at maximum figure of merit is bounded from the upper side by the analytical function: [Formula: see text], where [Formula: see text].
- Published
- 2022
14. Performance optimization of single and two-stage micro/nano-scaled heat pumps with internal and external irreversibilities
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Jizhou He, Ke Lü, Yueheng Lan, Wenjie Nie, and Aixi Chen
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Microchannel ,Materials science ,020209 energy ,Mechanical Engineering ,Heat pump and refrigeration cycle ,Non-equilibrium thermodynamics ,02 engineering and technology ,Building and Construction ,Mechanics ,Management, Monitoring, Policy and Law ,Coefficient of performance ,021001 nanoscience & nanotechnology ,Isothermal process ,law.invention ,General Energy ,law ,Heat transfer ,0202 electrical engineering, electronic engineering, information engineering ,Isobaric process ,0210 nano-technology ,Heat pump - Abstract
Based on the thermosize effects of a confined ideal Maxwellian gas, we established a model of micro/nano-scaled heat pump including two isothermal and two isobaric processes, where the Joule-like heating effect was analyzed in detail by using the nonequilibrium thermodynamic theory. Further, in order to improve the performance of a single thermosize device, a model of two-stage micro/nano-scaled heat pump with multiple micro/nano components is for the first time put forward. The general expressions of heating load and coefficient of performance for the single and the two-stage heat pump are derived. The influences of the internal and external irreversibilities of the system, i.e., Fourier heat flow and the Joule-like heating and the finite rate heat transfer with the reservoirs, on the performance characteristic of thermosize devices are studied in detail. Moreover, we also discuss the effect of the allocation the thermosize components on the optimal performance of the two-stage micro/nano-scaled heat pump cycle. It is found that in the presence of the internal and external irreversibilities, the two kinds of the micro/nano-scaled heat pump can achieve specific heating performance. In particular, when the total number M of the thermosize components is fixed, both the maximum of the optimal coefficient of performance Φ opt , max and the maximum of the heating load Π opt , max corresponding to the optimal coefficient of performance appear near n = M / 2 with n being the number of the thermosize elements of the top stage. The results obtained here show several main irreversibility source of the micro/nano-scaled heat pump and have potential applications in the efficient utilization and conversion of energy in the microchannel system using gas.
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- 2018
15. Fluctuations in irreversible quantum Otto engines
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Shoubao Zhu, Guangqian Jiao, Jianhui Wang, Jizhou He, and Yong-li Ma
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Physics ,Work (thermodynamics) ,Thermal efficiency ,Isochoric process ,Relative power ,Probability density function ,01 natural sciences ,010305 fluids & plasmas ,0103 physical sciences ,Statistical physics ,Finite time ,Duration (project management) ,010306 general physics ,Quantum - Abstract
We derive the general probability distribution function of stochastic work for quantum Otto engines in which both the isochoric and driving processes are irreversible due to finite time duration. The time-dependent work fluctuations, average work, and thermodynamic efficiency are explicitly obtained for a complete cycle operating with an analytically solvable two-level system. The effects of the irreversibility originating from finite-time cycle operation on the thermodynamic efficiency, work fluctuations, and relative power fluctuations are discussed.
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- 2021
16. Three-terminal refrigerator based on resonant-tunneling quantum wells
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Jizhou He, Zebin Lin, Wei Li, Yun Yun Yang, and Jianghui Wang
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Physics ,Landauer formula ,Refrigerator car ,Biasing ,Coefficient of performance ,01 natural sciences ,Projection (linear algebra) ,010305 fluids & plasmas ,0103 physical sciences ,Atomic physics ,Negative temperature ,010306 general physics ,Quantum well ,Quantum tunnelling - Abstract
A three-terminal refrigerator based on resonant-tunneling quantum wells is proposed. With the help of the Landauer formula, the expressions for the cooling rate and the coefficient of performance (COP) are derived. The working regions of the refrigerator are determined and the three-dimensional projection graphs of the cooling rate and the COP varying with the positions of the two energy levels are plotted. Moreover, the influence of the bias voltage, the asymmetric factor, and the temperature difference on the optimal performance parameters is analyzed in detail. Finally, the performance characteristics of the refrigerator in the case of negative temperature difference are discussed.
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- 2020
17. Quantum Otto engine working with interacting spin systems: Finite power performance in stochastic thermodynamics
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Jianhui Wang, Yingying Hong, Jizhou He, and Yuling Xiao
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Physics ,Spins ,Maximum power principle ,Power performance ,Thermodynamics ,01 natural sciences ,010305 fluids & plasmas ,Power (physics) ,law.invention ,Otto engine ,law ,0103 physical sciences ,010306 general physics ,Quantum ,Spin-½ - Abstract
A quantum Otto engine using two-interacting spins as its working medium is analyzed within framework of stochastic thermodynamics. The time-dependent power fluctuations and average power are explicitly derived for a complete cycle of engine operation. We find that the efficiency and power fluctuations are affected significantly by interparticle interactions, but both of them become interaction-independent under maximal power via optimizing the external control parameter. The behavior of the efficiency at maximum power is further explained by analyzing the optimal protocol of the engine.
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- 2020
18. Dynamic robustness of endoreversible Carnot refrigerator working in the maximum performance per cycle time
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Ke Lü, Wenjie Nie, and Jizhou He
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Multidisciplinary ,Dynamical systems theory ,lcsh:R ,Refrigerator car ,lcsh:Medicine ,02 engineering and technology ,Mechanics ,Coefficient of performance ,021001 nanoscience & nanotechnology ,01 natural sciences ,Heat capacity ,Article ,symbols.namesake ,Thermal conductivity ,Linearization ,0103 physical sciences ,Thermal ,symbols ,lcsh:Q ,010306 general physics ,0210 nano-technology ,Carnot cycle ,lcsh:Science ,Mathematics - Abstract
In this work, we study the dynamic robustness of an endoreversible Carnot cycle working at the maximum per-unit-time performance regime, based on the linearization technique for dynamical systems and the local stability analysis. Our analysis is focused on the endoreversible Carnot refrigerator model, which works in the maximum per-unit-time coefficient of performance. At the steady-state of the maximum performance, the expressions of the relaxation times describing the stability of the system are derived. It is found that the relaxation times in the cycle condition are the function of thermal conductances σh and σc, the temperatures of the heat reservoirs Th and Tc, and the heat capacity C. The influence of the temperature ratio τ = Tc/Th and the thermal conductance ratio σr = σh/σc on the relaxation times is discussed in detail. The results obtained here are useful and provide a potential guidance for the design of an endoreversible Carnot refrigerator working in the maximum performance per cycle time optimization condition.
- Published
- 2018
19. Identification of hub genes related to silicone-induced immune response in rats
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Qingfeng Li, Hengyu Du, Xiao Liang, Haizhou Li, Xiaolu Huang, Yiwen Zhou, Ran Duan, Jizhou He, Bangda Chai, Rui Jin, and Wenhui Liu
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silicone implant ,0301 basic medicine ,Microarray ,WGCNA ,business.industry ,autoimmunity ,GATA3 ,hub genes ,Context (language use) ,medicine.disease_cause ,Autoimmunity ,03 medical and health sciences ,TLR2 ,030104 developmental biology ,0302 clinical medicine ,Immune system ,Oncology ,Immunity ,TLR6 ,Immunology ,Medicine ,business ,microarray ,030217 neurology & neurosurgery ,Research Paper - Abstract
// Xiaolu Huang 1, * , Yiwen Zhou 1, * , Wenhui Liu 1 , Haizhou Li 1 , Xiao Liang 1 , Rui Jin 1 , Hengyu Du 1 , Jizhou He 1 , Bangda Chai 1 , Ran Duan 1 and Qingfeng Li 1 1 Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R.China * These authors contributed equally to this work and should be considered as co-author Correspondence to: Qingfeng Li, email: dr.liqingfeng@shsmu.edu.cn Keywords: silicone implant, autoimmunity, microarray, WGCNA, hub genes Received: July 04, 2017 Accepted: September 21, 2017 Published: October 06, 2017 ABSTRACT Silicone implants are used widely in the field of plastic surgery and are used in a large population. However, their safety profile, especially the silicone-induced immune response, has been a major concern for plastic surgeons for decades. It has been hypothesized that there is a cause and effect relation between silicone and immunity, but this is controversial. The objective of the present study was to determine the hub genes and key pathways related to silicone implant–induced immune responses in a rat model. In addition to cluster and enrichment analyses, we used weighted gene co-expression network analysis (WGCNA) to examine the gene expression profiles in a systematic context. A total five genes ( Fes , Aif1 , Gata3 , Tlr6 , Tlr2 ) were identified as hub genes that are most likely related to the silicone-induced immune response, four of which ( Aif1 , Gata3 , Tlr6 , Tlr2 ) have been associated with autoimmunity as target genes or disease markers. The Toll-like receptor signaling pathway ( p < 0.01, fold enrichment: 7.01) and systemic lupus erythematosus signaling pathway ( p < 0.05, fold enrichment: 5.01), which are considered strongly associated with autoimmunity, were significantly enriched in the silicone-implanted skin samples. The results indicate that silicone implants might trigger the localized immune response, as various immune reaction genes were detected after silicone implantation. The identified five hub genes will hopefully serve as novel therapeutic targets for silicone-related complications and the associated autoimmune diseases.
- Published
- 2017
20. Quantum Otto refrigerators in finite-time cycle period
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Jianhui Wang, Jizhou He, Yang Xiao, Guangqian Jiao, and Yongli Ma
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Physics ,Quantum electrodynamics ,General Physics and Astronomy ,Finite time ,Quantum ,Period (music) - Abstract
Finite-time cycle period for a quantum Otto machine implies that either an adiabatic stroke or an isochoric process proceeds in finite time duration. The quantum Otto refrigerators under consideration consist of two adiabatic strokes, where the system (isolated from the heat reservoir) undergoes finite-time unitary transformation, and two isochoric steps, where the system may not reach thermal equilibrium even at the respective ends of the two stages due to finite-time interaction intervals. Using two-time projective measurement method, we find the probability distribution functions of both coefficient of performance and cooling load, which are dependent on the time duration along each process. With these distributions we find the analytical expressions for the performance parameters as well as their fluctuations. We then numerically determine the performance and fluctuations for the refrigerator operating with a two-level system employed in a recent experimental implementation. Our results clarify the role of finite-time durations of four processes on the performance and fluctuations of the quantum Otto refrigerators.
- Published
- 2021
21. 'Stamp Perforation' Technique for Correction of Prominent Mandibular Angle
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Jizhou He, Qingfeng Li, Liang-gang Yu, Feng Xie, Hainan Zhu, and Bowen Gao
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Adult ,Male ,Facial proportion ,Adolescent ,Esthetics ,medicine.medical_treatment ,Perforation (oil well) ,Dentistry ,Facial artery ,Cosmetic Techniques ,Mandible ,Mandibular angle ,Resection ,03 medical and health sciences ,Postoperative Complications ,0302 clinical medicine ,Asian People ,medicine.artery ,medicine ,Humans ,Ostectomy ,030223 otorhinolaryngology ,Reduction (orthopedic surgery) ,business.industry ,Osteotomy ,Prominent mandible ,030220 oncology & carcinogenesis ,Female ,Surgery ,business - Abstract
Resection of a prominent mandibular angle is commonly used in Eastern society to improve the lower one third facial proportion. Historically, this procedure had a high complication rate, such as severe bleeding, asymmetry of the angle reduction, and "second mandibular angle." A safer and more effective way of performing such procedures is needed. The aim of this study is to introduce 3 instruments, a tunable guide handpiece, milling cutter, and flywheel, which were invented by the author, as well as a related ostectomy technique for correcting prominent mandibular angles using a modified full-thickness marginal ostectomy of the mandibular corpus angle, named the "stamp perforation" technique. This technique has 4 highlights: First, it ensures a smooth symmetric contour. Second, it prevents the risks of rupture of the inferior alveolar vessel and facial artery, ensuring the safety of this approach. Third, the "stamp perforation" technique eases the removal of bone fragments, shortening the operation time. Fourth, the recovery time of patients treated with this approach is much shorter than with the traditional approaches. From January 2006 to January 2016, 1106 patients underwent the surgery to contour the prominent mandible angles, and satisfactory results were achieved. Thus, we recommend the instruments as well as the "stamp perforation" technique for correcting prominent mandibular angles, and we hope that our 10 years of experience could provide a reference for other plastic surgeons.
- Published
- 2017
22. A three-terminal quantum dot heat engine based on ideal resonant tunneling
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JiaWei Wang, JiZhou He, Hao Su, and QinYun Zhao
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Physics ,Heat current ,Maximum power principle ,Computer Networks and Communications ,Energy conversion efficiency ,Thermodynamics ,Mechanics ,Coefficient of performance ,symbols.namesake ,Solar cell efficiency ,Control and Systems Engineering ,Mechanical efficiency ,symbols ,Carnot cycle ,Heat engine - Abstract
In this paper, the model of a three-terminal quantum dot heat engine consists of two quantum dots with a single energy level, a cavity and two electron reservoirs is established. According to Landauer formula the expressions for the heat current, the output power and the efficiency are derived analytically. The performance characteristic curves of the output power versus the efficiency are plotted by numerical calculation. Moreover, the optimal performance parameters are determined. Then we optimize the output power and the efficiency respectively, the influence of the width of energy level and the heat leak on performance of the three-terminal thermoelectric heat engine is discussed. Lastly, the variation of the corresponding efficiency at the maximum power output with the Carnot efficiency between two reservoirs is discussed and the corresponding efficiency is compared with Carnot efficiency and CA efficiency. It is shown that this three-terminal heat engine is irreversible due to the existence of the width of energy level and the heat leak. Thus the curve of the power output versus the efficiency is a loop-shaped one. And due to the heat leak, the characteristics of the efficiency and the width of energy level is a non-monotone curve. The efficiency at the maximum power will be greater than the CA efficiency when the heat leak and the width of energy level are not taken into account.
- Published
- 2016
23. Finite-power performance of quantum heat engines in linear response
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Jizhou He, Yong-li Ma, Qin Liu, and Jianhui Wang
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Physics ,Maximum power principle ,Entropy production ,Mechanics ,01 natural sciences ,Brayton cycle ,010305 fluids & plasmas ,symbols.namesake ,0103 physical sciences ,Heat transfer ,symbols ,Otto cycle ,010306 general physics ,Carnot cycle ,Adiabatic process ,Heat engine - Abstract
We investigate the finite-power performance of quantum heat engines working in the linear response regime where the temperature gradient is small. The engine cycles with working substances of ideal harmonic systems consist of two heat transfer and two adiabatic processes, such as the Carnot cycle, Otto cycle, and Brayton cycle. By analyzing the optimal protocol under maximum power we derive the explicitly analytic expression for the irreversible entropy production, which becomes the low dissipation form in the long duration limit. Assuming the engine to be endoreversible, we derive the universal expression for the efficiency at maximum power, which agrees well with that obtained from the phenomenological heat transfer laws holding in the classical thermodynamics. Through appropriate identification of the thermodynamic fluxes and forces that a linear relation connects, we find that the quantum engines under consideration are tightly coupled, and the universality of efficiency at maximum power is confirmed at the linear order in the temperature gradient.
- Published
- 2019
24. Finite-time performance of a quantum heat engine with a squeezed thermal bath
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Jianhui Wang, Yong-li Ma, and Jizhou He
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Physics ,Work (thermodynamics) ,Steady state ,Maximum power principle ,Thermodynamics ,Inverse ,Context (language use) ,01 natural sciences ,010305 fluids & plasmas ,symbols.namesake ,0103 physical sciences ,Thermal ,symbols ,010306 general physics ,Carnot cycle ,Analytic function - Abstract
We consider the finite-time performance of a quantum Otto engine working between a hot squeezed and a cold thermal bath at inverse temperatures β_{h} and β_{c}(>β_{h}) with (k_{B}≡1)β=1/T. We derive the analytical expressions for work, efficiency, power, and power fluctuations, in which the squeezing parameter is involved. By optimizing the power output with respect to two frequencies, we derive the efficiency at maximum power as η_{mp}=(η_{C}^{gen})^{2}/[η_{C}^{gen}-(1-η_{C}^{gen})ln(1-η_{C}^{gen})], where the generalized Carnot efficiency η_{C}^{gen} in the high-temperature or small squeezing limit simplifies to an analytic function of squeezing parameter γ: η_{C}^{gen}=1-β_{h}/[β_{c}cosh(2γ)]. Within the context of irreversible thermodynamics, we demonstrate that the expression of efficiency at maximum power satisfies a general form derived from nonlinear steady state heat engines. We show that, the power fluctuations are considerably increased, although the engine efficiency is enhanced by squeezing.
- Published
- 2019
25. Universal Expression of Efficiency at Maximum Power: A Quantum-Mechanical Brayton Engine Working with a Single Particle Confined in a Power-Law Trap
- Author
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Wei-Sheng Li, Jizhou He, Jianhui Wang, Yiming Lai, and Zhuolin Ye
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Physics ,Physics and Astronomy (miscellaneous) ,Maximum power principle ,Thermodynamics ,01 natural sciences ,Brayton cycle ,Power law ,010305 fluids & plasmas ,Power (physics) ,Superposition principle ,Bounded function ,Quantum mechanics ,0103 physical sciences ,Exponent ,010306 general physics ,Quantum - Abstract
We propose a quantum-mechanical Brayton engine model that works between two superposed states, employing a single particle confined in an arbitrary power-law trap as the working substance. Applying the superposition principle, we obtain the explicit expressions of the power and efficiency, and find that the efficiency at maximum power is bounded from above by the function: η+ = θ/(θ + 1), with θ being a potential-dependent exponent.
- Published
- 2015
26. Optimal performance of three-terminal nanowire heat engine based on one-dimensional ballistic conductors
- Author
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Yunyun Yang, Jizhou He, Shuai Xu, and Wei Li
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Materials science ,Nanostructure ,Terminal (electronics) ,business.industry ,Nanowire ,Optoelectronics ,Condensed Matter Physics ,business ,Electrical conductor ,Mathematical Physics ,Atomic and Molecular Physics, and Optics ,Energy (signal processing) ,Heat engine - Published
- 2020
27. Oxygen defect boosted photocatalytic hydrogen evolution from hydrogen sulfide over active {0 0 1} facet in anatase TiO2
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Ying Zhou, Meng Dan, Jizhou He, Fang Wang, Yuehan Cao, Shan Yu, and Qing Cai
- Subjects
Photocurrent ,Anatase ,Materials science ,Hydrogen ,Doping ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,Surfaces and Interfaces ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Photochemistry ,01 natural sciences ,Oxygen ,0104 chemical sciences ,Surfaces, Coatings and Films ,Dielectric spectroscopy ,Adsorption ,chemistry ,Vacancy defect ,0210 nano-technology - Abstract
In this work, the oxygen defect strategy was conducted to promote photo-splitting H2S into hydrogen (H2) on the typical anatase TiO2 with active {0 0 1} facet for the first time. Density functional theory (DFT) calculation results illustrate that surface oxygen vacancy can efficiently facilitate the electron transition across the forbidden band and enhance the surface adsorption ability with more negative adsorption energies of −0.82 to −2.85 eV for H2S and its fragments than that of 0.24 to −0.90 eV on the perfect surface. Importantly, the energy barrier is reduced by 1.58 eV in maximum along the reaction paths on the defected surface, and the changes of rate-determining step lead to H2 as the final product. In addition, the time-resolved fluorescence tests, photocurrent measurements and electrochemical impedance spectroscopy demonstrate that the oxygen vacancies can effectively separate photo-generated electron-hole pairs. As a result, the photocatalytic activities of H2 evolution from H2S on TiO2 {0 0 1} doped with oxygen vacancies have been significantly enhanced from 21.44 μmol g−1 h−1 to 95.25 μmol g−1 h−1. This enhanced photoactivity is due to the low recombination of photo-generated carriers, the favorable surface adsorption and reaction activity induced by oxygen vacancies.
- Published
- 2020
28. Efficiency and power of minimally nonlinear irreversible heat engines with broken time-reversal symmetry
- Author
-
Min Zhang, Jianhui Wang, Qin Liu, Wei Li, and Jizhou He
- Subjects
Maximum power principle ,05.70.Ln ,General Physics and Astronomy ,FOS: Physical sciences ,lcsh:Astrophysics ,01 natural sciences ,Article ,010305 fluids & plasmas ,symbols.namesake ,lcsh:QB460-466 ,0103 physical sciences ,Limit (mathematics) ,lcsh:Science ,010306 general physics ,nonlinear irreversible ,Condensed Matter - Statistical Mechanics ,Heat engine ,Physics ,Statistical Mechanics (cond-mat.stat-mech) ,heat engine ,Mechanics ,lcsh:QC1-999 ,Symmetry (physics) ,Power (physics) ,Nonlinear system ,T-symmetry ,symbols ,broken time-reversal symmetry ,lcsh:Q ,Carnot cycle ,lcsh:Physics ,efficiency at maximum power - Abstract
We study the minimally nonlinear irreversible heat engines in which the time-reversal symmetry for the systems may be broken. The expressions for the power and the efficiency are derived, in which the effects of the nonlinear terms due to dissipations are included. We show that, as within the linear responses, the minimally nonlinear irreversible heat engines can enable attainment of Carnot efficiency at positive power. We also find that the Curzon-Ahlborn limit imposed on the efficiency at maximum power can be overcome if the time-reversal symmetry is broken.
- Published
- 2018
29. Universality of maximum-work efficiency of a cyclic heat engine based on a finite system of ultracold atoms
- Author
-
Yingying Hu, Jizhou He, Jianhui Wang, and Zhuolin Ye
- Subjects
Physics ,Multidisciplinary ,Work output ,Particle number ,Science ,Thermodynamics ,01 natural sciences ,Heat capacity ,Article ,010305 fluids & plasmas ,Universality (dynamical systems) ,symbols.namesake ,Ultracold atom ,0103 physical sciences ,symbols ,Medicine ,010306 general physics ,Carnot cycle ,Finite set ,Heat engine - Abstract
We study the performance of a cyclic heat engine which uses a small system with a finite number of ultracold atoms as its working substance and works between two heat reservoirs at constant temperatures T h and T c (
- Published
- 2017
30. Endoreversible quantum heat engines in the linear response regime
- Author
-
Honghui Wang, Jianhui Wang, and Jizhou He
- Subjects
Physics ,Thermal reservoir ,Entropy production ,Thermodynamics ,Mechanics ,Thermal conduction ,01 natural sciences ,010305 fluids & plasmas ,Quantum master equation ,0103 physical sciences ,Heat transfer ,010306 general physics ,Adiabatic process ,Thermodynamic process ,Heat engine - Abstract
We analyze general models of quantum heat engines operating a cycle of two adiabatic and two isothermal processes. We use the quantum master equation for a system to describe heat transfer current during a thermodynamic process in contact with a heat reservoir, with no use of phenomenological thermal conduction. We apply the endoreversibility description to such engine models working in the linear response regime and derive expressions of the efficiency and the power. By analyzing the entropy production rate along a single cycle, we identify the thermodynamic flux and force that a linear relation connects. From maximizing the power output, we find that such heat engines satisfy the tight-coupling condition and the efficiency at maximum power agrees with the Curzon-Ahlborn efficiency known as the upper bound in the linear response regime.
- Published
- 2017
31. Microcanonical finite-size scaling of an ideal Bose gas in a box
- Author
-
Jizhou He, Jianhui Wang, and Honghui Wang
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Partition function (statistical mechanics) ,Gas in a box ,Specific heat ,Bose gas ,Condensed Matter::Other ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,Microcanonical ensemble ,Quantum mechanics ,Critical energy ,0103 physical sciences ,Condensed Matter::Statistical Mechanics ,Statistical physics ,010306 general physics ,Scaling - Abstract
We derive an exact recursive scheme to determine exactly the microcanonical partition function of a finite Bose system. Such a recursive approach is identical to that previously obtained within the context of counting statistics. Within the exact microcanonical ensemble, we study microcanonical finite-size scaling behaviors of condensate fraction and specific heat around the critical energy ϵ c for the finite ideal Bose system. We show that the microcanonical scaling functions governing the various critical behaviors are universal in the ideal Bose-Einstein condensates.
- Published
- 2017
32. Performance analysis of a tunneling thermoelectric heat engine with nano-scaled quantum well
- Author
-
Nian Liu, Teng Qiu, Jizhou He, and Xiaoguang Luo
- Subjects
Materials science ,business.industry ,Biasing ,General Chemistry ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Thermal radiation ,Thermoelectric effect ,Optoelectronics ,General Materials Science ,business ,Quantum tunnelling ,Quantum well ,Leakage (electronics) ,Heat engine - Abstract
A numerical model of a nano-scaled thermoelectric heat engine with InP/InAs/InP trilayer quantum well (QW) is investigated. The expressions of those performance parameters, such as current, power output, and efficiency are expressed. By numerical calculation, the resonant tunneling behavior of electrons in the QW is described, which seems like a very good energy selective electron mechanism for the heat engine. After considering the radiation heat leakage, for fixed layer thicknesses of the QW, the optimum working regions of the heat engine with respect to the chemical potentials and the bias voltage are obtained numerically under the economic criterion. From these results, the power output can be increased by narrowing down the layer thicknesses. In addition, owing to the radiant heat leakage, the efficiency initially increases in the working regions and then decreases when the layer thicknesses increase gradually, from which one can obtain a maximum efficiency by optimizing layer thicknesses of QW. These results calculated here may provide a guide for the optimum designs of tunneling thermoelectric devices.
- Published
- 2014
33. Efficiency at Maximum Power Output of a Quantum-Mechanical Brayton Cycle
- Author
-
Yuan Yuan, Jian-Hui Wang, Yong Gao, and Jizhou He
- Subjects
Trap (computing) ,Physics ,Physics and Astronomy (miscellaneous) ,Maximum power principle ,Harmonic ,Isobaric process ,Particle ,Thermodynamics ,Trapping ,Mechanics ,Brayton cycle ,Quantum - Abstract
The performance in finite time of a quantum-mechanical Brayton engine cycle is discussed, without introduction of temperature. The engine model consists of two quantum isoenergetic and two quantum isobaric processes, and works with a single particle in a harmonic trap. Directly employing the finite-time thermodynamics, the efficiency at maximum power output is determined. Extending the harmonic trap to a power-law trap, we find that the efficiency at maximum power is independent of any parameter involved in the model, but depends on the confinement of the trapping potential.
- Published
- 2014
34. The impact of energy spectrum width in the energy selective electron low-temperature thermionic heat engine at maximum power
- Author
-
Teng Qiu, Jizhou He, Nian Liu, Ruiwen Li, Cong Li, and Xiaoguang Luo
- Subjects
Physics ,Maximum power principle ,Computer simulation ,General Physics and Astronomy ,Thermionic emission ,Electron ,Atomic physics ,Constant (mathematics) ,Upper and lower bounds ,Energy (signal processing) ,Heat engine - Abstract
A model of thermionic heat engine with the energy selective electron mechanism is studied. Analytical expressions of the power output and efficiency of this device are derived at low temperature, where the chemical potentials of the reservoirs are assumed to be constant. After discussing the impact of the energy spectrum width of the energy selective electron mechanism, we find two bounds ( η ± ) of efficiency at maximum power exist naturally. When the energy spectrum width increases gradually from zero and then to the semi-infinite case with the infinite upper limit, the efficiency at maximum power decreases monotonously from the upper bound η + to the lower bound η − at a given temperature ratio of the cold and hot reservoirs. The two bound are given by numerical simulation and by an analytical expression respectively. These results may provide some guidance for the application of the practical energy selective electron heat engines.
- Published
- 2013
35. The aeroelastic effects on the scatter phenomenon of wind-tunnel data
- Author
-
NaiZhen Zhou, Ye Zhengyin, JiZhou He, BaoFang Song, and YueWen Jiang
- Subjects
Airfoil ,Engineering ,Wing ,business.industry ,General Engineering ,Stall (fluid mechanics) ,Structural engineering ,Aerodynamics ,Aeroelasticity ,Aerodynamic force ,Swept wing ,General Materials Science ,business ,Wind tunnel - Abstract
The unsteady Reynolds-averaged Navier-Stokes equations coupled with the k-ω SST turbulence model are solved to obtain the steady and unsteady aerodynamic forces for airfoils and wings. The effects of vibration types and amplitudes on aerodynamic forces of airfoils and wings are studied. The deformation characteristics of a swept wing induced by steady aerodynamic load are presented. It is found that for a vibrating elastic wing at small and medium incidences, its mean aerodynamic loads are almost the same as those obtained from the static one. On the contrary, at high incidences especially around the stall incidence, the vibration may change the mean values. In addition, the larger amplitude is, the larger discrepancy will be. For a swept wing, the steady aerodynamic loads usually lead to the “pitching down” effect on the wing tip which delays the stall compared with a rigid one; But this phenomenon dose not occur on a aeroelastic wing which can induce the separation ahead and trigger the stall. The above conclusions are in good agreement with the scatter characteristics of wind-tunnel data. The reason why the data obtained from wind tunnel and CFD are different is also analyzed. Meanwhile, it can be an explanation for scatter phenomenon of wind-tunnel data, especially for high incidence cases, which remains a puzzle so far.
- Published
- 2012
36. Thermal entangled quantum heat engine
- Author
-
Xian He, Jie Zheng, and Jizhou He
- Subjects
Statistics and Probability ,Thermal equilibrium ,Physics ,Work (thermodynamics) ,Quantum mechanics ,Otto cycle ,Quantum entanglement ,Condensed Matter Physics ,Adiabatic process ,Classical XY model ,Quantum ,Heat engine - Abstract
Based on a two-qubit Heisenberg XY model, we construct a four-level entangled quantum heat engine (QHE). It is an interesting quantum Otto cycle where the exchange constant is fixed and only the magnetic field is varied during the adiabatic steps. The expressions for several thermodynamic quantities such as the heat transferred, the work and the efficiency are derived. Moreover, the influence of the entanglement on the thermodynamic quantities is investigated numerically. Several interesting features of the variation of the heat transferred, the work and the efficiency with the concurrences of the thermal entanglement of different thermal equilibrium states are obtained. Finally, we discussed the maximum efficiency of the QHE.
- Published
- 2012
37. Thermal entangled four-level quantum Otto heat engine
- Author
-
JiZhou He and Xian He
- Subjects
Thermal equilibrium ,Physics ,Work (thermodynamics) ,Quantum mechanics ,Isotropy ,Thermal ,General Physics and Astronomy ,Quantum Physics ,Quantum entanglement ,Quantum ,Heat engine ,Magnetic field - Abstract
Based on a two-qubit isotropic Heisenberg XXX model with a constant external magnetic field, we construct a four-level entangled quantum heat engine (QHE). The expressions for several thermodynamic quantities such as the heat transferred, the work and efficiency are derived. Moreover, the influence of the entanglement on the thermodynamic quantities is investigated analytically and numerically. Several interesting features of the variation of the heat transferred, the work and the efficiency with the concurrences of the thermal entanglement of different thermal equilibrium states are obtained.
- Published
- 2012
38. Thermodynamics of an Ideal Bose Gas with a Finite Number of Particles Confined in a Three-Dimensional Quartic Trap
- Author
-
Jianhui Wang, Bo Zhuang, and Jizhou He
- Subjects
Condensed Matter::Quantum Gases ,Physics ,education.field_of_study ,Condensed matter physics ,Bose gas ,Transition temperature ,Population ,Thermodynamics ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Grand canonical ensemble ,Quantum mechanics ,Quartic function ,General Materials Science ,Ideal (ring theory) ,education ,Physical quantity ,Boson - Abstract
Within an exact canonical-ensemble treatment, we investigate the thermodynamics for a finite number of ideal bosons confined in a three-dimensional quartic trap. We calculate several physical quantities including the specific heat C N , chemical potential μ, condensate fraction 〈n 0〉/N, root-mean-square fluctuations δn 0 of the condensate population, and transition temperature T c . We discuss the particle-number dependence of T c through proposing three T c definitions, which are compared with ones derived in the grand canonical ensemble.
- Published
- 2012
39. Classification of Phase Transitions for an Ideal Bose Gas in a d-Dimensional Quartic Potential
- Author
-
Chenyan Zhang, Jianhui Wang, and Jizhou He
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Phase transition ,Ideal (set theory) ,Bose gas ,Condensed matter physics ,Transition temperature ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,law.invention ,law ,Quantum mechanics ,Quartic function ,General Materials Science ,Finite set ,Bose–Einstein condensate ,Curse of dimensionality - Abstract
Based on the classification scheme of phase transitions, we study the phase transitions for an ideal Bose gas with a finite number N of particles trapped in a d-dimensional quartic potential. We find that the presence and nature of phase transition depend on the dimensionality of the quartic potential. Proposing three different definitions of transition temperature, we discuss either N or d dependence of transition temperature for the ideal Bose condensate in the d-dimensional quartic potential.
- Published
- 2011
40. Phase transitions for an ideal Bose condensate trapped in a quartic potential
- Author
-
Jizhou He and J.H. Wang
- Subjects
Condensed Matter::Quantum Gases ,Quantum phase transition ,Physics ,Phase transition ,Condensed matter physics ,Particle number ,Bose gas ,Atomic and Molecular Physics, and Optics ,law.invention ,law ,Quantum mechanics ,Quartic function ,Thermodynamic limit ,Ideal (ring theory) ,Bose–Einstein condensate - Abstract
Based on the classification scheme of phase transitions, we study the phase transitions for an ideal Bose gas with a finite number of particles confined in a three-dimensional quartic trap. We show that the phase transition of an ideal Bose gas in the three-dimensional quartic trap is of third order for finite particle numbers, quite different from the fact that the phase transition is of first order in the thermodynamic limit. We discuss the effects of finite particle numbers on the nature of the phase transitions, and determine the dependence of transition temperature on particle number.
- Published
- 2011
41. Micro-/nanoscaled irreversible Otto engine cycle with friction loss and boundary effects and its performance characteristics
- Author
-
Jizhou He, Wenjie Nie, Qinghong Liao, and ChunQiang Zhang
- Subjects
Work output ,Isentropic process ,Chemistry ,Isochoric process ,Mechanical Engineering ,Thermodynamics ,Building and Construction ,Pollution ,Industrial and Manufacturing Engineering ,Friction loss ,law.invention ,General Energy ,Otto engine ,Surface-area-to-volume ratio ,law ,Otto cycle ,Thermal de Broglie wavelength ,Electrical and Electronic Engineering ,Civil and Structural Engineering - Abstract
An irreversible cycle model of the micro-/nanoscaled Otto engine cycle with internal friction loss is established. The general expressions of the work output and efficiency of the cycle are calculated based on the finite system thermodynamic theory, in which the quantum boundary effect of gas particles as working substance and the mechanical Casimir effect of gas system are considered. It is found that, for a micro-/nanoscaled Otto cycle devices, the work output W and efficiency η of the cycle can be expressed as the functions of the temperature ratio τ of the two heat reservoirs, the volume ratio rV and the surface area ratio rA of the two isochoric processes, the dimensionless thermal wavelength λ and other parameters of cycle, while for a macroscaled Otto cycle devices, the work output W0 and efficiency η0 of the cycle are independent of the surface area ratio rA and the dimensionless thermal wavelength λ. Further, the influence of boundary of cycle on the performance characteristics of the micro-/nanoscaled Otto cycle are analyzed in detail by introducing the output ratio W/W0 and efficiency ratio η/η0. The results present the general performance characteristics of a micro-/nanoscaled Otto cycle and may serve as the basis for the design of a realistic Otto cycle device in micro-/nanoscale.
- Published
- 2010
42. Coefficient of performance and its bounds of minimally nonlinear irreversible refrigerator at arbitrary optimal value
- Author
-
Jianhui Wang, Qin Liu, Jizhou He, and Min Zhang
- Subjects
Thermal reservoir ,Refrigerator car ,Statistical and Nonlinear Physics ,Mechanics ,Coefficient of performance ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Nonlinear system ,0103 physical sciences ,010306 general physics ,Constant (mathematics) ,Value (mathematics) ,Mathematics - Abstract
We study the performance of minimally nonlinear irreversible refrigerators which works between a hot and cold heat reservoir of constant temperatures [Formula: see text] and [Formula: see text], respectively. Applying optimization criterion [Formula: see text] or [Formula: see text], we analyze the coefficient of performance (COP) at arbitrary value of [Formula: see text] or [Formula: see text] and thus obtain the upper and lower bounds of the COP. Our results show that, for the optimized, tightly-coupled refrigerators, a small loss away from the maximum value of either [Formula: see text] or [Formula: see text] figure of merit means a larger gain in the COP.
- Published
- 2018
43. Performance characteristics of a quantum Diesel refrigeration cycle
- Author
-
Jizhou He, Hao Wang, and Sanqiu Liu
- Subjects
Stirling engine ,Isentropic process ,Physics::Instrumentation and Detectors ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Heat pump and refrigeration cycle ,Astrophysics::Instrumentation and Methods for Astrophysics ,Energy Engineering and Power Technology ,Refrigeration ,Thermodynamics ,Mechanics ,Coefficient of performance ,Physics::Classical Physics ,Brayton cycle ,Computer Science::Other ,law.invention ,symbols.namesake ,Diesel fuel ,Fuel Technology ,Nuclear Energy and Engineering ,law ,symbols ,Physics::Chemical Physics ,Carnot cycle - Abstract
The Diesel refrigeration cycle using an ideal quantum gas as the working substance is called quantum Diesel refrigeration cycle, which is different from Carnot, Ericsson, Brayton, Otto and Stirling refrigeration cycles. For ideal quantum gases, a corrected equation of state, which considers the quantum behavior of gas particles, is used instead of the classical one. The purpose of this paper is to investigate the effect of quantum gas as the working substance on the performance of a quantum Diesel refrigeration cycle. It is found that coefficients of performance of the cycle are not affected by the quantum degeneracy of the working substance, which is the same as that of the classical Diesel refrigeration cycle. However, the refrigeration load is different from those of the classical Diesel refrigeration cycle. Lastly, the influence of the quantum degeneracy on the performance characteristics of the quantum Diesel refrigeration cycle operated in different temperature regions is discussed.
- Published
- 2009
44. Performance analysis and parametric optimum criteria of a quantum Otto heat engine with heat transfer effects
- Author
-
Hao Wang, Jizhou He, and Sanqiu Liu
- Subjects
Engineering ,Maximum power principle ,business.industry ,Isochoric process ,Energy Engineering and Power Technology ,Mechanical engineering ,Mechanics ,Industrial and Manufacturing Engineering ,law.invention ,Otto engine ,law ,Compression ratio ,Heat transfer ,Otto cycle ,business ,Heat engine ,Parametric statistics - Abstract
The influence of both the quantum degeneracy and the finite rate heat transfer between the working substance and the cylinder wall on the optimal performance of an Otto engine cycle is investigated. Expressions for several important parameters such as the power output and efficiency are derived. By using numerical solutions, the curves of the power output and efficiency varying with the compression ratio of two isochoric processes are presented. It is found that there are optimal values of the compression ratio at which the power output and efficiency attain their maximum. In particular, the optimal performance of the cycle in strong and weak gas degeneracy and the high temperature limit are discussed in detail. The distinctions and connections between the quantum Otto engine and the classical are revealed. Moreover, the maximum power output and efficiency and the corresponding relevant parameters are calculated, and consequently, the optimization criteria of some important parameters such as the power output, efficiency and compression ratio of the working substance are obtained.
- Published
- 2009
45. Performance characteristic of a Stirling refrigeration cycle in micro/nano scale
- Author
-
Wenjie Nie, Jianqiang Du, and Jizhou He
- Subjects
Statistics and Probability ,Materials science ,Stirling engine ,Scale (ratio) ,Thermodynamics ,Refrigeration ,Coefficient of performance ,Condensed Matter Physics ,law.invention ,Surface-area-to-volume ratio ,Volume (thermodynamics) ,law ,Nano ,Stirling cycle - Abstract
The aim of the paper is to present the performance characteristics of a Stirling refrigeration cycle in micro/nano scale, in which the working substance of cycle is an ideal Maxwellian gas. Due to the quantum boundary effect on the gas particles confined in the finite domain, the cycle no longer possesses the condition of perfect regeneration. The inherent regenerative losses, the refrigeration heat and coefficient of performance (COP) of the cycle are derived. It is found that, for the micro/nano scaled Stirling refrigeration cycle devices, the refrigeration heat and COP of cycle all depend on the surface area of the system (boundary of cycle) besides the temperature of the heat reservoirs, the volume of system and other parameters, while for the macro scaled refrigeration cycle devices, the refrigeration heat and COP of cycle are independent of the surface area of the system. Variations of the refrigeration heat ratio r R and the COP ratio r e with the temperature ratio τ and volume ratio r V for the different surface area ratio r A are examined, which reveals the influence of the boundary of cycle on the performance of a micro/nano scaled Stirling refrigeration cycle. The results are useful for designing of a micro/nano scaled Stirling cycle device and may conduce to confirming experimentally the quantum boundary effect in the micro/nano scaled devices.
- Published
- 2009
46. Optimum criteria of an irreversible quantum Brayton refrigeration cycle with an ideal Bose gas
- Author
-
Hao Wang, Jizhou He, and Sanqiu Liu
- Subjects
Materials science ,Bose gas ,Heat transfer ,Cooling load ,Thermodynamics ,Refrigeration ,Electrical and Electronic Engineering ,Coefficient of performance ,Condensed Matter Physics ,Adiabatic process ,Optimal control ,Brayton cycle ,Electronic, Optical and Magnetic Materials - Abstract
An irreversible cycle model of the quantum Brayton refrigeration cycle is established, in which finite-time processes and irreversibility in the two adiabatic processes are taken into account. On the basis of the thermodynamic properties of an ideal Bose gas, by using the optimal control-theory, the mathematical expressions for several important performance parameters, such as the coefficient of performance, power input and cooling load, are derived and some important performance parameters, e.g., the temperatures of the working substance at several important state-points, are optimized. By means of numerical predictions, the optimal performance characteristic curves of a Bose–Brayton refrigeration cycle are obtained and analyzed. Furthermore, some optimal operating regions including those for the cooling load, coefficient of performance and the temperatures of the cyclic working substance at the two important state-points are determined and evaluated. Finally, several special cases are discussed in detail.
- Published
- 2008
47. Local stability analysis of an irreversible Carnot heat engine
- Author
-
Jizhou He, Wenjie Nie, and Xinfa Deng
- Subjects
Thermal efficiency ,Materials science ,General Engineering ,Thermodynamics ,Heat transfer coefficient ,Condensed Matter Physics ,Heat capacity rate ,symbols.namesake ,Heat flux ,Heat transfer ,symbols ,Carnot heat engine ,Carnot cycle ,Heat engine - Abstract
The local stability of an irreversible Carnot heat engine has been studied based on the linearization technique for dynamical systems and local stability analysis. At two steady-states of the maximum power output and the maximum efficiency the expressions of the relaxation time of an irreversible Carnot heat engine are derived. It is found that the relaxation time is a function of the heat-transfer coefficient α and β, heat capacity C, temperatures of the heat reservoirs TH and TL, the degree of internal irreversibility ϕ and the internal heat conductance k. The influence of heat resistance, internal irreversibility and heat leak on the relaxation time is discussed. Phase portraits for the trajectories are presented in some representative cases. The results obtained here are more general and useful for the realistic irreversible heat engine than endoreversible heat engine.
- Published
- 2008
48. Performance analysis of a thermosize micro/nano heat engine
- Author
-
Jizhou He and Wenjie Nie
- Subjects
Physics ,Thermoelectric generator ,Thermodynamic cycle ,Thermoelectric effect ,Heat exchanger ,General Physics and Astronomy ,Isobaric process ,Thermodynamics ,Ideal gas ,Isothermal process ,Heat engine - Abstract
In a recent paper [A. Sisman, I. Muller, Phys. Lett. A 320 (2004) 360] the thermodynamic properties of ideal gases confined in a narrow box were examined theoretically. The so-called “thermosize effects” similar to thermoelectric effects, such as Seebeck-like thermosize effect, Peltier-like thermosize effect and Thomson-like thermosize effect, were analyzed. Like the thermoelectric generator, based on the thermosize effects we have established a model of micro/nano scaled ideal gas heat engine cycle which includes two isothermal and two isobaric processes. The expressions of power output and efficiency of this cycle in the two cases of reversible and irreversible heat exchange are derived and the optimal performance characteristics of the heat engine is discussed by some numerical example. The results obtained here will provide theoretical guidance for the design of micro/nano scaled device.
- Published
- 2008
49. Performance characteristics of an irreversible magnetic Brayton refrigeration cycle
- Author
-
Xin-Fa Deng, Jizhou He, and Xin Wu
- Subjects
Materials science ,Isentropic process ,Physics::Instrumentation and Detectors ,Mechanical Engineering ,Refrigeration ,Thermodynamics ,Building and Construction ,Coefficient of performance ,Physics::Classical Physics ,Brayton cycle ,Curie's law ,Paramagnetism ,Thermodynamic cycle ,Magnetic refrigeration - Abstract
Based on the thermodynamic properties of a paramagnetic salt, an irreversible model of the magnetic Brayton refrigeration cycle is established, in which the working substance is a special paramagnetic material. The expressions of the important performance parameters, such as the coefficient of performance, refrigeration load and work input, are derived. Moreover, the optimal performance parameters are obtained at the maximum coefficient of performance. The results obtained here may include the ones of the magnetic Brayton refrigeration cycle using the magnetic material obeyed the Curie law as the working substance, the magnetic Brayton refrigeration cycle without regeneration and the eversible magnetic Brayton refrigeration cycle. Therefore, the results obtained here have general significance and will be helpful to deeply understand the performance of a magnetic Brayton refrigeration cycle.
- Published
- 2008
50. Performance of a quantum heat engine cycle working with harmonic oscillator systems
- Author
-
ZhiYuan Mao, JianHui Wang, and JiZhou He
- Subjects
Physics ,Work (thermodynamics) ,Classical mechanics ,Maximum power principle ,Entropy production ,Control theory ,Thermodynamic cycle ,Harmonic ,Harmonic oscillator ,First law of thermodynamics ,Heat engine - Abstract
A cycle model of an irreversible heat engine working with harmonic systems is established in this paper. Based on the equation of motion of an operator in the Heisenberg picture and semi-group approach, the first law of thermodynamics for a harmonic system and the time evolution of the system are obtained. The general expressions for several important parameters, such as the work, efficiency, power output, and rate of entropy production are derived. By means of numerical analysis, the optimally operating regions and the optimal values of performance parameters of the cycle are determined under the condition of maximum power output. At last, some special cases, such as high temperature limit and frictionless case, are discussed in brief.
- Published
- 2007
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