An extended cellular automata model with modified floor field for evacuation
Da-Hui Qin, Yun-Fei Duan, Dong Cheng, Ming-Zhu Su, and Yong-Bo Shao
The floor field model has been widely used in evacuation simulation research based on cellular automata model. However, conventional methods of setting floor field will lead to highly insufficient utilization of the exit area when people gather on one side of the exit. In this study, an extended cellular automata model with modified floor field is proposed to solve this problem. Additionally, a congestion judgment mechanism is integrated in our model, whereby people can synthetically judge the degree of congestion and distance in front of them to determine whether they need to change another exit to evacuate or not. We contrasted the simulation results of the conventional floor field model, the extended model proposed in this paper, and Pathfinder software in a same scenario. It is demonstrated that this extended model can ameliorate the problem of insufficient utilization of the exit area and the trajectory of pedestrian movement and the crowd shape of pedestrians in front of exit in this new model are more realistic than those of the other two models. The findings have implications for modeling pedestrian evacuation.The floor field model has been widely used in evacuation simulation research based on cellular automata model. However, conventional methods of setting floor field will lead to highly insufficient utilization of the exit area when people gather on one side of the exit. In this study, an extended cellular automata model with modified floor field is proposed to solve this problem. Additionally, a congestion judgment mechanism is integrated in our model, whereby people can synthetically judge the degree of congestion and distance in front of them to determine whether they need to change another exit to evacuate or not. We contrasted the simulation results of the conventional floor field model, the extended model proposed in this paper, and Pathfinder software in a same scenario. It is demonstrated that this extended model can ameliorate the problem of insufficient utilization of the exit area and the trajectory of pedestrian movement and the crowd shape of pedestrians in front of exit in this new model are more realistic than those of the other two models. The findings have implications for modeling pedestrian evacuation.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/abad1b
Influence of CdS films synthesized by different methods on the photovoltaic performance of CdTe/CdS thin film solar cells
Jun Wang, Yuquan Wang, Cong Liu, Meiling Sun, Cao Wang, Guangchao Yin, Fuchao Jia, Yannan Mu, Xiaolin Liu, and Haibin Yang
The cadmium sulphide (CdS) film is grown on cadmium telluride (CdTe) nanorods (NRs) arrays by different methods such as chemical bath deposition (CBD), magnetron sputtering (MS), and homogenous precipitation (HP) techniques. The impact of various deposition methods is explored in detail on the growth of CdTe/CdS composite film, the CdTe/CdS interface property, and solar cell efficiency. Compared to the CBD and HP methods, the MS method can improve the growth of the CdS on CdTe NRs with high crystalline quality. The device based on the CdS film prepared by the MS method demonstrates excellent photovoltaic performance, which has the potential for applications in solar cells.The cadmium sulphide (CdS) film is grown on cadmium telluride (CdTe) nanorods (NRs) arrays by different methods such as chemical bath deposition (CBD), magnetron sputtering (MS), and homogenous precipitation (HP) techniques. The impact of various deposition methods is explored in detail on the growth of CdTe/CdS composite film, the CdTe/CdS interface property, and solar cell efficiency. Compared to the CBD and HP methods, the MS method can improve the growth of the CdS on CdTe NRs with high crystalline quality. The device based on the CdS film prepared by the MS method demonstrates excellent photovoltaic performance, which has the potential for applications in solar cells.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/abad22
Temperature-dependent barrier height inhomogeneities in PTB7:PC71BM-based organic solar cells
Brahim Ait Ali, Reda Moubah, Abdelkader Boulezhar, and Hassan Lassri
We report on the temperature-dependent Schottky barrier in organic solar cells based on PTB7:PC71BM. The ideality factor is found to increase with temperature decreasing, which is explained by a model in which the solar cell is taken as Schottky barrier diode. Accordingly, the dark current in the device originates from the thermally emitted electrons across the Schottky barrier. The fittings obtained with the thermal emission theory are systematically studied at different temperatures. It is concluded that the blend/Ca/Al interface presents great inhomogeneity, which can be described by 2 sets of Gaussian distributions with large zero bias standard deviations. With the decrease of temperature, electrons favor going across the Schottky barrier patches with lower barrier height and as a consequence the ideally factor significantly increases at low temperature.We report on the temperature-dependent Schottky barrier in organic solar cells based on PTB7:PC71BM. The ideality factor is found to increase with temperature decreasing, which is explained by a model in which the solar cell is taken as Schottky barrier diode. Accordingly, the dark current in the device originates from the thermally emitted electrons across the Schottky barrier. The fittings obtained with the thermal emission theory are systematically studied at different temperatures. It is concluded that the blend/Ca/Al interface presents great inhomogeneity, which can be described by 2 sets of Gaussian distributions with large zero bias standard deviations. With the decrease of temperature, electrons favor going across the Schottky barrier patches with lower barrier height and as a consequence the ideally factor significantly increases at low temperature.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/aba5fc
Determination of potassium sorbate and sorbic acid in agricultural products using THz time-domain spectroscopy
Yuying Jiang, Guangming Li, Ming Lv, Hongyi Ge, and Yuan Zhang
The aim of this study was to investigate the feasibility of detecting potassium sorbate (PS) and sorbic acid (SA) in agricultural products using THz time-domain spectroscopy (THz-TDS). The absorption spectra of PS and SA were measured from 0.2 to 1.6 THz at room temperature. The main characteristic absorption peaks of PS and SA in polyethylene and powdered agricultural products with different weight ratios were detected and analyzed. Interval partial least squares (iPLS) combined with a particle swarm optimization and support vector classification (PSO-SVC) algorithm was proposed in this paper. iPLS was used for frequency optimization, and the PSO-SVC algorithm was used for spectrum analysis of the preservative content based on the optimal spectrum ranges. Optimized PSO-SVC models were obtained when the THz spectrum from the PS/SA mixture was divided into 11 or 12 subintervals. The optimal penalty parameter c and kernel parameter g were found to be 1.284 and 0.863 for PS (0.551–1.487 THz), 1.374 and 0.906 for SA (0.454–1.216 THz), respectively. The preliminary results indicate that THz-TDS can be an effective nondestructive analytical tool used for the quantitative detection of additives in agricultural products.The aim of this study was to investigate the feasibility of detecting potassium sorbate (PS) and sorbic acid (SA) in agricultural products using THz time-domain spectroscopy (THz-TDS). The absorption spectra of PS and SA were measured from 0.2 to 1.6 THz at room temperature. The main characteristic absorption peaks of PS and SA in polyethylene and powdered agricultural products with different weight ratios were detected and analyzed. Interval partial least squares (iPLS) combined with a particle swarm optimization and support vector classification (PSO-SVC) algorithm was proposed in this paper. iPLS was used for frequency optimization, and the PSO-SVC algorithm was used for spectrum analysis of the preservative content based on the optimal spectrum ranges. Optimized PSO-SVC models were obtained when the THz spectrum from the PS/SA mixture was divided into 11 or 12 subintervals. The optimal penalty parameter c and kernel parameter g were found to be 1.284 and 0.863 for PS (0.551–1.487 THz), 1.374 and 0.906 for SA (0.454–1.216 THz), respectively. The preliminary results indicate that THz-TDS can be an effective nondestructive analytical tool used for the quantitative detection of additives in agricultural products.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/ab9f25
Dynamics and coherence resonance in a thermosensitive neuron driven by photocurrent
Ying Xu, Minghua Liu, Zhigang Zhu, and Jun Ma
A feasible neuron model can be effective to estimate the mode transition in neural activities in a complex electromagnetic environment. When neurons are exposed to electromagnetic field, the continuous magnetization and polarization can generate nonlinear effect on the exchange and propagation of ions in the cell, and then the firing patterns can be regulated completely. The conductivity of ion channels can be affected by the temperature and the channel current is adjusted for regulating the excitability of neurons. In this paper, a phototube and a thermistor are used to the functions of neural circuit. The phototube is used to capture external illumination for energy injection, and a continuous signal source is obtained. The thermistor is used to percept the changes of temperature, and the channel current is changed to adjust the excitability of neuron. This functional neural circuit can encode the external heat (temperature) and illumination excitation, and the dynamics of neural activities is investigated in detail. The photocurrent generated in the phototube can be used as a signal source for the neural circuit, and the thermistor is used to estimate the conduction dependence on the temperature for neurons under heat effect. Bifurcation analysis and Hamilton energy are calculated to explore the mode selection. It is found that complete dynamical properties of biological neurons can be reproduced in spiking, bursting, and chaotic firing when the phototube is activated as voltage source. The functional neural circuit mainly presents spiking states when the photocurrent is handled as a stable current source. Gaussian white noise is imposed to detect the occurrence of coherence resonance. This neural circuit can provide possible guidance for investigating dynamics of neural networks and potential application in designing sensitive sensors.A feasible neuron model can be effective to estimate the mode transition in neural activities in a complex electromagnetic environment. When neurons are exposed to electromagnetic field, the continuous magnetization and polarization can generate nonlinear effect on the exchange and propagation of ions in the cell, and then the firing patterns can be regulated completely. The conductivity of ion channels can be affected by the temperature and the channel current is adjusted for regulating the excitability of neurons. In this paper, a phototube and a thermistor are used to the functions of neural circuit. The phototube is used to capture external illumination for energy injection, and a continuous signal source is obtained. The thermistor is used to percept the changes of temperature, and the channel current is changed to adjust the excitability of neuron. This functional neural circuit can encode the external heat (temperature) and illumination excitation, and the dynamics of neural activities is investigated in detail. The photocurrent generated in the phototube can be used as a signal source for the neural circuit, and the thermistor is used to estimate the conduction dependence on the temperature for neurons under heat effect. Bifurcation analysis and Hamilton energy are calculated to explore the mode selection. It is found that complete dynamical properties of biological neurons can be reproduced in spiking, bursting, and chaotic firing when the phototube is activated as voltage source. The functional neural circuit mainly presents spiking states when the photocurrent is handled as a stable current source. Gaussian white noise is imposed to detect the occurrence of coherence resonance. This neural circuit can provide possible guidance for investigating dynamics of neural networks and potential application in designing sensitive sensors.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/ab9dee
Entrainment mechanism of the cyanobacterial circadian clock induced by oxidized quinone
Ying Li, Guang-Kun Zhang, and Zi-Gen Song
The circadian clock is a self-sustained biological oscillator which can be entrained by environmental signals. The cyanobacteria circadian clock is the simplest one, which is composed of the proteins KaiA, KaiB and KaiC. The phosphorylation/dephosphorylation state of KaiC exhibits a circadian oscillator. KaiA and KaiB activate KaiC phosphorylation and dephosphorylation respectively. CikA competing with KaiA for the same binding site on KaiB affects the phosphorylation state of KaiC. Quinone is a signaling molecule for entraining the cyanobacterial circadian clock which is oxidized at the onset of darkness and reduced at the onset of light, reflecting the environmental light–dark cycle. KaiA and CikA can sense external signals by detecting the oxidation state of quinone. However, the entrainment mechanism is far from clear. We develop an enhanced mathematical model including oxidized quinone sensed by KaiA and CikA, with which we present a detailed study on the entrainment of the cyanobacteria circadian clock induced by quinone signals. We find that KaiA and CikA sensing oxidized quinone pulse are related to phase advance and delay, respectively. The time of oxidized quinone pulse addition plays a key role in the phase shifts. The combination of KaiA and CikA is beneficial to the generation of entrainment, and the increase of signal intensity reduces the entrainment phase. This study provides a theoretical reference for biological research and helps us understand the dynamical mechanisms of cyanobacteria circadian clock.The circadian clock is a self-sustained biological oscillator which can be entrained by environmental signals. The cyanobacteria circadian clock is the simplest one, which is composed of the proteins KaiA, KaiB and KaiC. The phosphorylation/dephosphorylation state of KaiC exhibits a circadian oscillator. KaiA and KaiB activate KaiC phosphorylation and dephosphorylation respectively. CikA competing with KaiA for the same binding site on KaiB affects the phosphorylation state of KaiC. Quinone is a signaling molecule for entraining the cyanobacterial circadian clock which is oxidized at the onset of darkness and reduced at the onset of light, reflecting the environmental light–dark cycle. KaiA and CikA can sense external signals by detecting the oxidation state of quinone. However, the entrainment mechanism is far from clear. We develop an enhanced mathematical model including oxidized quinone sensed by KaiA and CikA, with which we present a detailed study on the entrainment of the cyanobacteria circadian clock induced by quinone signals. We find that KaiA and CikA sensing oxidized quinone pulse are related to phase advance and delay, respectively. The time of oxidized quinone pulse addition plays a key role in the phase shifts. The combination of KaiA and CikA is beneficial to the generation of entrainment, and the increase of signal intensity reduces the entrainment phase. This study provides a theoretical reference for biological research and helps us understand the dynamical mechanisms of cyanobacteria circadian clock.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/aba615
A 3D biophysical model for cancer spheroid cell-enhanced invasion in collagen-oriented fiber microenvironment
Miaomiao Hai, Yanping Liu, Ling Xiong, Guoqiang Li, Gao Wang, Hongfei Zhang, Jianwei Shuai, Guo Chen, and Liyu Liu
The process of in situ tumors developing into malignant tumors and exhibiting invasive behavior is extremely complicated . From a biophysical point of view, it is a phase change process affected by many factors, including cell-to-cell, cell-to-chemical material, cell-to-environment interaction, etc. In this study, we constructed spheroids based on green fluorescence metastatic breast cancer cells MDA-MB-231 to simulate malignant tumors in vitro, while constructed a three-dimensional (3D) biochip to simulate a micro-environment for the growth and invasion of spheroids. In the experiment, the 3D spheroid was implanted into the chip, and the oriented collagen fibers controlled by collagen concentration and injection rate could guide the MDA-MB-231 cells in the spheroid to undergo directional invasion. The experiment showed that the oriented fibers greatly accelerated the invasion speed of MDA-MB-231 cells compared with the traditional uniform tumor micro-environment, namely obvious invasive branches appeared on the spheroids within 24 hours. In order to analyze this interesting phenomenon, we have developed a quantitative analyzing approach to explore strong angle correlation between the orientation of collagen fibers and invasive direction of cancer cell. The results showed that the oriented collagen fibers produced by the chip can greatly stimulate the invasion potential of cancer cells. This biochip is not only conducive to modeling cancer cell metastasis and studying cell invasion mechanisms, but also has the potential to build a quantitative evaluation platform that can be used in future chemical drug treatments.The process of in situ tumors developing into malignant tumors and exhibiting invasive behavior is extremely complicated . From a biophysical point of view, it is a phase change process affected by many factors, including cell-to-cell, cell-to-chemical material, cell-to-environment interaction, etc. In this study, we constructed spheroids based on green fluorescence metastatic breast cancer cells MDA-MB-231 to simulate malignant tumors in vitro, while constructed a three-dimensional (3D) biochip to simulate a micro-environment for the growth and invasion of spheroids. In the experiment, the 3D spheroid was implanted into the chip, and the oriented collagen fibers controlled by collagen concentration and injection rate could guide the MDA-MB-231 cells in the spheroid to undergo directional invasion. The experiment showed that the oriented fibers greatly accelerated the invasion speed of MDA-MB-231 cells compared with the traditional uniform tumor micro-environment, namely obvious invasive branches appeared on the spheroids within 24 hours. In order to analyze this interesting phenomenon, we have developed a quantitative analyzing approach to explore strong angle correlation between the orientation of collagen fibers and invasive direction of cancer cell. The results showed that the oriented collagen fibers produced by the chip can greatly stimulate the invasion potential of cancer cells. This biochip is not only conducive to modeling cancer cell metastasis and studying cell invasion mechanisms, but also has the potential to build a quantitative evaluation platform that can be used in future chemical drug treatments.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/ab9c02
Oscillation of S5 helix under different temperatures in determination of the open probability of TRPV1 channel
Tie Li, Jun-Wei Li, Chun-Li Pang, Hailong An, Yi-Zhao Geng, and Jing-Qin Wang
Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodel sensory receptor and can be activated by moderate temperature (≥ 43 °C). Though extensive researches on the heat-activation mechanism revealed some key elements that participate in the heat-sensation pathway, the detailed thermal-gating mechanism of TRPV1 is still unclear. We investigate the heat-activation process of TRPV1 channel using the molecular dynamics simulation method at different temperatures. It is found that the favored state of the supposed upper gate of TRPV1 cannot form constriction to ion permeation. Oscillation of S5 helix originated from thermal fluctuation and forming/breaking of two key hydrogen bonds can transmit to S6 helix through the hydrophobic contact between S5 and S6 helix. We propose that this is the pathway from heat sensor of TRPV1 to the opening of the lower gate. The heat-activation mechanism of TRPV1 presented in this work can help further functional study of TRPV1 channel.Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodel sensory receptor and can be activated by moderate temperature (≥ 43 °C). Though extensive researches on the heat-activation mechanism revealed some key elements that participate in the heat-sensation pathway, the detailed thermal-gating mechanism of TRPV1 is still unclear. We investigate the heat-activation process of TRPV1 channel using the molecular dynamics simulation method at different temperatures. It is found that the favored state of the supposed upper gate of TRPV1 cannot form constriction to ion permeation. Oscillation of S5 helix originated from thermal fluctuation and forming/breaking of two key hydrogen bonds can transmit to S6 helix through the hydrophobic contact between S5 and S6 helix. We propose that this is the pathway from heat sensor of TRPV1 to the opening of the lower gate. The heat-activation mechanism of TRPV1 presented in this work can help further functional study of TRPV1 channel.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/aba600
High performance Cu2O film/ZnO nanowires self-powered photodetector by electrochemical deposition
Deshuang Guo, Wei Li, Dengkui Wang, Bingheng Meng, Dan Fang, and Zhipeng Wei
Self-powered photodetectors based on nanomaterials have attracted lots of attention for several years due to their various advantages. In this paper, we report a high performance Cu2O/ZnO self-powered photodetector fabricated by using electrochemical deposition. ZnO nanowires arrays grown on indium-tin-oxide glass are immersed in Cu2O film to construct type-II band structure. The Cu2O/ZnO photodetector exhibits a responsivity of 0.288 mA/W at 596 nm without bias. Compared with Cu2O photoconductive detector, the responsivity of the Cu2O/ZnO self-powered photodetector is enhanced by about two times at 2 V bias. It is attributed to the high power conversion efficiency and the efficient separation of the photogenerated electron–hole pairs, which are provided by the heterojunction. The outstanding comprehensive performances make the Cu2O film/ZnO nanowires self-powered photodetector have great potential applications.Self-powered photodetectors based on nanomaterials have attracted lots of attention for several years due to their various advantages. In this paper, we report a high performance Cu2O/ZnO self-powered photodetector fabricated by using electrochemical deposition. ZnO nanowires arrays grown on indium-tin-oxide glass are immersed in Cu2O film to construct type-II band structure. The Cu2O/ZnO photodetector exhibits a responsivity of 0.288 mA/W at 596 nm without bias. Compared with Cu2O photoconductive detector, the responsivity of the Cu2O/ZnO self-powered photodetector is enhanced by about two times at 2 V bias. It is attributed to the high power conversion efficiency and the efficient separation of the photogenerated electron–hole pairs, which are provided by the heterojunction. The outstanding comprehensive performances make the Cu2O film/ZnO nanowires self-powered photodetector have great potential applications.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/aba610
Room-temperature electric control of exchange bias effect in CoO1 – δ/Co films using Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (110) substrates
Xin Wen, Rui Wu, Wen-Yun Yang, Chang-Sheng Wang, Shun-Quan Liu, Jing-Zhi Han, and Jin-Bo Yang
Significant electric control of exchange bias effect in a simple CoO1–δ/Co system, grown on piezoelectric Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (110) (PMN-PT) substrates, is achieved at room temperature. Obvious changes in both the coercivity field (HC) and the exchange bias field (HE), of 31% and 5%, respectively, have been observed when the electric field is applied to the substrate. While the change of coercivity is related to the enhanced uniaxial anisotropy in the ferromagnetic layer, the change of the exchange bias field can only originate from the spin reorientation in the antiferromagnetic CoO1–δ layer caused by the strain-induced magnetoelastic effect. A large HE/HC > 2, and HE ～ 110 Oe at room temperature, as well as the low-energy fabrication of this system, make it a practical system for spintronic device applications.Significant electric control of exchange bias effect in a simple CoO1–δ/Co system, grown on piezoelectric Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (110) (PMN-PT) substrates, is achieved at room temperature. Obvious changes in both the coercivity field (HC) and the exchange bias field (HE), of 31% and 5%, respectively, have been observed when the electric field is applied to the substrate. While the change of coercivity is related to the enhanced uniaxial anisotropy in the ferromagnetic layer, the change of the exchange bias field can only originate from the spin reorientation in the antiferromagnetic CoO1–δ layer caused by the strain-induced magnetoelastic effect. A large HE/HC > 2, and HE ～ 110 Oe at room temperature, as well as the low-energy fabrication of this system, make it a practical system for spintronic device applications.
- Apr. 29, 2021
- Chinese Physics B
- Vol. 29, Issue 9, (2020)
- DOI：10.1088/1674-1056/aba611
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