Flexible transparent antennas(FTAs)are widely used in wireless transmission fields,and their technological iterations are accelerating.However,the high losses caused by materials and structures limit the development o...Flexible transparent antennas(FTAs)are widely used in wireless transmission fields,and their technological iterations are accelerating.However,the high losses caused by materials and structures limit the development of FTAs with both high light transmission and high gain,and the rapid iteration rate demands greater process flexibility,which makes it difficult for existing technologies to achieve both demands.Here,we design a novel shell-core structure composite metal mesh(CMM)FTA to achieve extremely low skin depth loss and ohmic loss using skin effect and report a novel hybrid additive manufacturing method based on electric field oriented deposition to achieve efficient and flexible manufacturing of the unique Ag/Cu core-shell structure CMM FTA.The typical sample has a light transmittance of 80%(including substrate)when the sheet resistance is 0.29Ω·sq^(-1),and has excellent bending and torsion resistance.The peak gain in the working band is as high as 5.22 dB,and the efficiency is 80%,which is close to the performance of the opaque Cu patch antenna.It also realizes smooth and stable real-time wireless transmission under bending and long-distance conditions.This method addresses the shortcomings of FTAs,namely their high cost,low manufacturing efficiency,and low performance,especially in the rapid iterative development of antennas.展开更多
To investigate the microwave effect on the WC–Co alloys,WC–8 wt%Co alloy was fabricated by microwave sintering(MWS)in this paper.The results show that decarburization layer forms on the surface of the microwave-sint...To investigate the microwave effect on the WC–Co alloys,WC–8 wt%Co alloy was fabricated by microwave sintering(MWS)in this paper.The results show that decarburization layer forms on the surface of the microwave-sintered samples.WC grain coarsening in the core area is strongly suppressed by the decarburization effect.In addition,the microstructure of the MWS-fabri-cated alloy was compared to that of the alloy sintered by vacuum sintering(VS).Microstructural investigations by transmission electron microscopy(TEM)and energy dis-persive spectroscopy(EDS)show that more tungsten(29.50 wt%)is dissolved in the cobalt binder phase in microwave-sintered alloy than that in the vacuum-sintered samples.Finally,the formation mechanism of the surface layer by skin effect was discussed.展开更多
This paper proposes the‘skin effect’of the machining-induced damage at high strain rates.The paper first reviews the published research work on machining-induced damage and then identifies the governing factors that...This paper proposes the‘skin effect’of the machining-induced damage at high strain rates.The paper first reviews the published research work on machining-induced damage and then identifies the governing factors that dominate damage formation mechanisms.Among many influential factors,such as stress-strain field,temperature field,material responses to loading and loading rate,and crack initiation and propagation,strain rate is recognized as a dominant factor that can directly lead to the‘skin effect’of material damage in a loading process.The paper elucidates that material deformation at high strain rates(>103 s−1)leads to the embrittlement,which in turn contributes to the‘skin effect’of subsurface damage.The paper discusses the‘skin effect’based on the principles of dislocation kinetics and crack initiation and propagation.It provides guidance to predicting the material deformation and damage at a high strain-rate for applications ranging from the armor protection,quarrying,petroleum drilling,and high-speed machining of engineering materials(e.g.ceramics and SiC reinforced aluminum alloys).展开更多
Micro fabrication of freeform surface parts made of hard and brittle materials is always a tough job in micro machining field. This paper tries to fabricate freeform surface feature by using smooth surface of tool ele...Micro fabrication of freeform surface parts made of hard and brittle materials is always a tough job in micro machining field. This paper tries to fabricate freeform surface feature by using smooth surface of tool electrode after tool wear in micro EDM. According to the skin effect theory, the tool end shape in the stage of uniform wear can be changed by adjusting the frequency of discharge pulse. The electrical energy distributing rule of tool electrode section in RC circuit has been investigated under the influence of skin effect, and the law of spark location change has been summarized. The experimental studies demonstrate that different shapes of tool ends can be achieved by varying the pulse frequencies of discharge power supply. Additionally, a micro part of freeform surface feature with high precision and good surface quality has been successfully obtained by micro EDM through adopting the smooth surface after tool wear.展开更多
The skin effect in the reversely switched dynistor （RSD） devices is investigated in this paper. Based on the plasma bipolar drift model of the RSD, the current density distributions on the chip are simulated with co...The skin effect in the reversely switched dynistor （RSD） devices is investigated in this paper. Based on the plasma bipolar drift model of the RSD, the current density distributions on the chip are simulated with considering the skin effect. The results indicate that the current density on the border can be several hundred to a thousand A/cm2 higher than that in the center of the chip. The skin effect becomes more prominent as the voltage increases and the inductance decreases in the main circuit. The phenomenon that most of a certain group of chips break over on the border has proved the existence of the skin effect.展开更多
The non-Hermitian skin effect breaks the conventional bulk–boundary correspondence and leads to non-Bloch topological invariants.Inspired by the fact that the topological protected zero modes are immune to perturbati...The non-Hermitian skin effect breaks the conventional bulk–boundary correspondence and leads to non-Bloch topological invariants.Inspired by the fact that the topological protected zero modes are immune to perturbations,we construct a partner of a non-Hermitian system by getting rid of the non-Hermitian skin effect.Through adjusting the imbalance hopping,we find that the existence of zero-energy boundary states still dictate the bulk topological invariants based on the band-theory framework.Two non-Hermitian Su–Schrieffer–Heeger(SSH)models are used to illuminate the ideas.Specially,we obtain the winding numbers in analytical form without the introduction of the generalized Brillouin zone.The work gives an alternative method to calculate the topological invariants of non-Hermitian systems.展开更多
We investigate novel features of three-dimensional non-Hermitian Weyl semimetals,paying special attention to the unconventional bulk-boundary correspondence.We use the non-Bloch Chern numbers as the tool to obtain the...We investigate novel features of three-dimensional non-Hermitian Weyl semimetals,paying special attention to the unconventional bulk-boundary correspondence.We use the non-Bloch Chern numbers as the tool to obtain the topological phase diagram,which is also confirmed by the energy spectra from our numerical results.It is shown that,in sharp contrast to Hermitian systems,the conventional(Bloch)bulk-boundary correspondence breaks down in non-Hermitian topological semimetals,which is caused by the non-Hermitian skin effect.We establish the non-Bloch bulk-boundary correspondence for non-Hermitian Weyl semimetals:the topological edge modes are determined by the non-Bloch Chern number of the bulk bands.Moreover,these topological edge modes can manifest as the unidirectional edge motion,and their signatures are consistent with the non-Bloch bulk-boundary correspondence.Our work establishes the non-Bloch bulk-boundary correspondence for non-Hermitian topological semimetals.展开更多
In most studies of microstrip circuits, the majority of researchers assume that the microstrip structures studied have flat metallic conductors of finite widths but without thickness. But in reality these types of str...In most studies of microstrip circuits, the majority of researchers assume that the microstrip structures studied have flat metallic conductors of finite widths but without thickness. But in reality these types of structures integrate metallic copper conductors of different thicknesses. If we neglect this thickness we introduce error in the electrical parameters of the microstrip structure, which affects the effective permittivity, the characteristic impedance, the adaptation of the circuit, the resonance frequency, etc. Given the importance of this parameter (thickness of the metal of micro rubon structures), rigorous electromagnetic modeling of the thick micro rubon line based on the skin effect phenomenon (In fact at high frequency the skin effect phenomenon occurs and the current only flows on the periphery of the conductor) has been proposed to improve the studied electric model and ensure the increase in the precision of the analysis method used: Wave concept iterative process. The good agreement between the simulated and published data justifies the improvement of the model.展开更多
The non-Hermitian skin effect is an iconic phenomenon characterized by the aggregation of eigenstates near the system boundaries in non-Hermitian systems.While extensively studied in one dimension,understanding the sk...The non-Hermitian skin effect is an iconic phenomenon characterized by the aggregation of eigenstates near the system boundaries in non-Hermitian systems.While extensively studied in one dimension,understanding the skin effect and extending the non-Bloch band theory to higher dimensions encounter a formidable challenge,primarily due to infinite lattice geometries or open boundary conditions.This work adopts a point-gap perspective and unveils that non-Hermitian skin effect in all spatial dimensions originates from point gaps.We introduce the concept of uniform spectra and reveal that regardless of lattice geometry,their energy spectra are universally given by the uniform spectra,even though their manifestations of skin modes may differ.Building on the uniform spectra,we demonstrate how to account for the skin effect with generic lattice cuts and establish the connections of skin modes across different geometric shapes via momentum-basis transformations.Our findings highlight the pivotal roles point gaps play,offering a unified understanding of the topological origin of non–Hermitian skin effect in all dimensions.展开更多
We concentrate on the skin effects and topological properties in the multilayer non-Hermitian Su−Schrieffer−Heeger (SSH) structure, by taking into account the nonreciprocal couplings between the different sublattices ...We concentrate on the skin effects and topological properties in the multilayer non-Hermitian Su−Schrieffer−Heeger (SSH) structure, by taking into account the nonreciprocal couplings between the different sublattices in the unit cells. Following the detailed demonstration of the theoretical method, we find that in this system, the skin effects and topological phase transitions induced by nonreciprocal couplings display the apparent parity effect, following the increase of the layer number of this SSH structure. On the one hand, the skin effect is determined by the parity of the layer number of this SSH system, as well as the parity of the band index of the bulk states. On the other hand, for the topological edge modes, such an interesting parity effect can also be observed clearly. Next, when the parameter disorders are taken into account, the zero-energy edge modes in the odd-layer structures tend to be more robust, whereas the other edge modes are easy to be destroyed. In view of these results, it can be ascertained that the findings in this work promote to understand the influences of nonreciprocal couplings on the skin effects and topological properties in the multilayer SSH lattices.展开更多
This article reviews recent developments in the non-Hermitian skin effect(NHSE),particularly on its rich interplay with topology.The review starts off with a pedagogical introduction on the modified bulk-boundary corr...This article reviews recent developments in the non-Hermitian skin effect(NHSE),particularly on its rich interplay with topology.The review starts off with a pedagogical introduction on the modified bulk-boundary correspondence,the synergy and hybridization of NHSE and band topology in higher dimensions,as well as,the associated topology on the complex energy plane such as spectral winding topology and spectral graph topology.Following which,emerging topics are introduced such as non-Hermitian criticality,dynamical NHSE phenomena,and the manifestation of NHSE beyond the traditional linear non-interacting crystal lattices,particularly its interplay with quantum many-body interactions.Finally,we survey the recent demonstrations and experimental proposals of NHSE.展开更多
Background: Magnetic resonance image-guided radiation therapy (MR-IGRT) promises more precise and effective radiation treatments compared to conventional IGRT by using real-time on-board MR imaging. Under the influenc...Background: Magnetic resonance image-guided radiation therapy (MR-IGRT) promises more precise and effective radiation treatments compared to conventional IGRT by using real-time on-board MR imaging. Under the influence of a magnetic field, however, secondary electrons exiting a surface can be forced in a circular path and re-enter the medium, resulting in dose increase at a beam-exit surface, called the electron return effect (ERE). The purpose of the study is to compare the exit skin dose computed by Monte Carlo dose calculation with measurements using an adult anthropomorphic phantom and to measure the effect of skin dose reduction by adding 1 cm-thick bolus. Method: The plan was compared with measurements using an adult anthropomorphic phantom combined with radiochromic films and thermoluminescent dosimeters. We also measured the skin dose reduction by adding 1 cm-thick bolus on the frontal surface of the phantom. Results: We found that 1 cm-thick bolus reduced the skin dose by up to 20% both in measurements and calculations. The plan was found to overestimate the measured skin dose by about 10% and there was no significant difference in the bolus effect between the breast skin and the skin (without breast attachment) doses. Conclusion: In conclusion, we confirmed the ERE effect on the anthropomorphic phantom under the magnetic field and the exit skin dose reduction by adding a bolus. Skin dose measurements using anthropomorphic phantom may be helpful to evaluate more realistic skin dose and the bolus effect in the magnetic field.展开更多
In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' ...In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' topical dose (52 μg/200 μl acetone ) of 7, 12-dimethylbenzanthracene (DMBA). To evaluate the anti-tumour initiating activity, BTP was topically applied twice a week for three weeks prior to DMBA application, followed by topical treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA) (5 μg/200 μl acetone, 2x/wk. ) as promoter. For evaluation of antitumor promoting activity, BTP was applied prior to each treatment of TPA. BTP application showed marked inhibitory effect as antitumour initiator as well as antitumour promoter in mouse skin medel of two-stage carcinogenesis. Since initiation involves genetic pathway and tumour promotion involves epigenetic pathway, it seems that BTP exerts its antitumorigenic effect by altering both genetic and epigenetic pathways展开更多
We studied the effects of butyric acid (BA) on mouse skin tumorigenesis using chronicanimal bioassays. Topical application of BA immediately after each treatment with 12-0-te-t radecanoyl phorbol-13-acetate (TPA) prom...We studied the effects of butyric acid (BA) on mouse skin tumorigenesis using chronicanimal bioassays. Topical application of BA immediately after each treatment with 12-0-te-t radecanoyl phorbol-13-acetate (TPA) promoter' inhi bi ted skint umors. The effect was depe n -dent on the dose of BA applied. BA showed no marked inhibitory effect on either skin tumorinitiation or complete tumorigenesis induced by dimet hyl benzant hracene (DMBA ). Si nce t u -mor promotion reportedly involves epigenetic events whereas tumor initiation or complete tu-morigenesis takes place through genetic pathways, it is Possible that BA exerts its antitumori-genic effects mainly by altering the epigenetic events responsible for tumor promotion. The re-sults of the study could further be used to study the mechanism of action and modification ofantitumorigenic effects of BA in combination with other substances展开更多
[ Objective] This study aimed to investigate the biological effects of laser-induced mutation on fibrous roots of yellow skin onion. [ Method] Wet seeds of two yellow skin onion cultivars were irradiated by CO2 laser ...[ Objective] This study aimed to investigate the biological effects of laser-induced mutation on fibrous roots of yellow skin onion. [ Method] Wet seeds of two yellow skin onion cultivars were irradiated by CO2 laser and He-Ne laser at three dosage levels separately. A randomized complete block design with three replications was adopted. The biological effects of laser-induced mutation on fibrous roots of Ll-generation yellow skin onion were investigated with biostatistics and physiological and biochemical methods. [Result] Significant variations in the biological effects caused by various laser treatments were observed in the length, quantity, fresh weight and activity of onion fibrous roots. Specifically, the variation in fibrous root length induced by different types of laser reached 5% significance level; significant variation was observed in fibrous roots of different onion cultivars induced by laser, while the variation among each treatment did not reach 5% sig- nifieance level ; the variation in fibrous root quantity induced by different dosage levels of laser reached 5% significance level ; laser radiation showed stimulating effect on root activity of onion. [ Conclusion] This study provided reference for laser-induced breeding of yellow skin onion.展开更多
Epilepsy is a neurodegenerative disease that interrupts the normal electrical activity of the brain and promotes abnormal wiring in this organ.Epileptic seizures are often associated with significant changes in the fu...Epilepsy is a neurodegenerative disease that interrupts the normal electrical activity of the brain and promotes abnormal wiring in this organ.Epileptic seizures are often associated with significant changes in the functioning of the autonomic nervous system(ANS).展开更多
A high peak power IPL system (Lumecca) was tested to determine the correlation between a high peak power and the successful treatment of pigmented and vascular lesions. Short pulse duration in the millisecond range an...A high peak power IPL system (Lumecca) was tested to determine the correlation between a high peak power and the successful treatment of pigmented and vascular lesions. Short pulse duration in the millisecond range and high peak power of 3.3 kW/cm<sup>2</sup> enabled selective and effective destruction, not only of pigment, but also of vessels in a comparable manner to a pulsed dye laser. Only one treatment session at a low fluence (8 - 16 J/cm<sup>2</sup>) was sufficient to achieve the desired results.展开更多
The skin is a formidable physical and biological barrier which communicates continuously with the outside of the body. And the stratum corneum, the outermost layer of human epidermis, plays a central role in the inter...The skin is a formidable physical and biological barrier which communicates continuously with the outside of the body. And the stratum corneum, the outermost layer of human epidermis, plays a central role in the interaction between the cutaneous tissue and the external environment. The horny layer, and more generally the whole skin layers, avoid the penetration of harmful exogenous agents, produce molecules named anti-microbial peptides which impact the composition of the cutaneous microbiota, regulate the internal corporal temperature, avoid the water loss from the inside of the body and constitute an incredible efficient anti-oxidant network. Nevertheless, nowadays, the skin is more and more solicited by the different elements of the cutaneous exposome, including atmospheric pollution and solar radiations, which can cause a dramatic acceleration of the skin ageing process. As a consequence, due to the multifunctional protective role of the skin, during the recent decade the cosmetic industry invested massively in the development of new raw materials and end-products (dermo-cosmetics) able to preserve an optimal state of the skin regarding the external environment. Based on their physical-chemical properties thermal spring waters, which are extremely rich in inorganics ions, are interesting and powerful candidates to be part, as integral component, of new efficient dermo-cosmetic formulations dedicated to protect the skin from the external stimuli. The aim of the present work was to investigate and characterize the activity of Jonzac thermal spring water on the skin. Using different models, we proved for the first time that Jonzac thermal spring water reinforces the barrier function of the skin by modulating the expression of key markers including filaggrin and human beta defensin 2 on ex vivo human skin. The ex vivo and in vivo hydration activity, by Raman spectroscopy and corneometry respectively, has been also demonstrated. We have also shown that Jonzac thermal spring water ameliorates significantly the cutaneous microrelief in vivo. To conclude, we characterize the soothing effect of Jonzac thermal spring water by the analysis of histamine release in Substance P treated skin explants and by measuring the redness of the skin following UV exposure of the skin in vivo. We observed that both parameters decreased following a preventive treatment of the skin with Jonzac thermal spring water. Taken together our results indicate that Jonzac thermal spring water is a promising and powerful dermo-cosmetic which can be used to preserve an optimal state of the cutaneous tissue.展开更多
As the Reynolds number increases, the skin friction has been identified as the dominant drag in many practical applications. In the present paper, the effects of the Reynolds number on the mean skin friction decomposi...As the Reynolds number increases, the skin friction has been identified as the dominant drag in many practical applications. In the present paper, the effects of the Reynolds number on the mean skin friction decomposition in turbulent channel flows up to Reτ= 5 200 are investigated based on two different methods, i.e., the FukagataIwamoto-Kasagi(FIK) identity(FUKAGATA, K., IWAMOTO, K., and KASAGI, N.Contribution of Reynolds stress distribution to the skin friction in wall-bounded flows.Physics of Fluids, 14(11), L73–L76(2002)) and the Renard-Deck(RD) identity(DECK,S., RENARD, N., LARAUFIE, R., and WEISS, P.′E. Large-scale contribution to mean wall shear stress in high-Reynolds-number flat-plate boundary layers up to Reθ= 13 650.Journal of Fluid Mechanics, 743, 202–248(2014)). The direct numerical simulation(DNS) data provided by Lee and Moser(LEE, M. and MOSER, R. D. Direct numerical simulation of turbulent channel flow up to Reτ≈ 5 200. Journal of Fluid Mechanics,774, 395–415(2015)) are used. For these two skin friction decomposition methods, their decomposed constituents are discussed and compared for different Reynolds numbers.The integrands of the decomposed constituents are locally analyzed across the boundary layer to assess the actions associated with the inhomogeneity and multi-scale nature of turbulent motion. The scaling of the decomposed constituents and their integrands are presented. In addition, the boundary layer is divided into three sub-regions to evaluate the contributive proportion of each sub-region with an increase in the Reynolds number.展开更多
The mathematic model of heat transfer through ventilated double glazing was verified with the measured data,which were from a test chamber equipped with glass face temperature,solar radiation,ambient temperature,and w...The mathematic model of heat transfer through ventilated double glazing was verified with the measured data,which were from a test chamber equipped with glass face temperature,solar radiation,ambient temperature,and wind speed measurement facility.After the model validation,the double-skin facade assessment was carried out through simulation with ESP-r software integrating thermal simulation and air low net work module.The air flow situation in the air gap was analyzed on the basis of the hourly air velocity simulation data within typical winter week,summer week,spring week and autumn week.The differences of chimney effect in different seasons were discussed,and the thermal loads resulted from the ventilated and unventilated double skin facade were presented.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52375348 and 52175331)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2020ZD04 and ZR2022ME014).
文摘Flexible transparent antennas(FTAs)are widely used in wireless transmission fields,and their technological iterations are accelerating.However,the high losses caused by materials and structures limit the development of FTAs with both high light transmission and high gain,and the rapid iteration rate demands greater process flexibility,which makes it difficult for existing technologies to achieve both demands.Here,we design a novel shell-core structure composite metal mesh(CMM)FTA to achieve extremely low skin depth loss and ohmic loss using skin effect and report a novel hybrid additive manufacturing method based on electric field oriented deposition to achieve efficient and flexible manufacturing of the unique Ag/Cu core-shell structure CMM FTA.The typical sample has a light transmittance of 80%(including substrate)when the sheet resistance is 0.29Ω·sq^(-1),and has excellent bending and torsion resistance.The peak gain in the working band is as high as 5.22 dB,and the efficiency is 80%,which is close to the performance of the opaque Cu patch antenna.It also realizes smooth and stable real-time wireless transmission under bending and long-distance conditions.This method addresses the shortcomings of FTAs,namely their high cost,low manufacturing efficiency,and low performance,especially in the rapid iterative development of antennas.
基金the National Natural Science Foundation of China(No.51274107)。
文摘To investigate the microwave effect on the WC–Co alloys,WC–8 wt%Co alloy was fabricated by microwave sintering(MWS)in this paper.The results show that decarburization layer forms on the surface of the microwave-sintered samples.WC grain coarsening in the core area is strongly suppressed by the decarburization effect.In addition,the microstructure of the MWS-fabri-cated alloy was compared to that of the alloy sintered by vacuum sintering(VS).Microstructural investigations by transmission electron microscopy(TEM)and energy dis-persive spectroscopy(EDS)show that more tungsten(29.50 wt%)is dissolved in the cobalt binder phase in microwave-sintered alloy than that in the vacuum-sintered samples.Finally,the formation mechanism of the surface layer by skin effect was discussed.
基金The authors would like to acknowledge the supports by the National Natural Science Foundation of China(Grant No.51575084)and the Peacock Program of Shenzhen(Grant No.KQJSCX20180322152221965).
文摘This paper proposes the‘skin effect’of the machining-induced damage at high strain rates.The paper first reviews the published research work on machining-induced damage and then identifies the governing factors that dominate damage formation mechanisms.Among many influential factors,such as stress-strain field,temperature field,material responses to loading and loading rate,and crack initiation and propagation,strain rate is recognized as a dominant factor that can directly lead to the‘skin effect’of material damage in a loading process.The paper elucidates that material deformation at high strain rates(>103 s−1)leads to the embrittlement,which in turn contributes to the‘skin effect’of subsurface damage.The paper discusses the‘skin effect’based on the principles of dislocation kinetics and crack initiation and propagation.It provides guidance to predicting the material deformation and damage at a high strain-rate for applications ranging from the armor protection,quarrying,petroleum drilling,and high-speed machining of engineering materials(e.g.ceramics and SiC reinforced aluminum alloys).
基金Supported by the National Natural Science Foundation of China （50635040） and the National Science Foundation of USA（CMMI-0728294 and CMMI- 0928873）
文摘Micro fabrication of freeform surface parts made of hard and brittle materials is always a tough job in micro machining field. This paper tries to fabricate freeform surface feature by using smooth surface of tool electrode after tool wear in micro EDM. According to the skin effect theory, the tool end shape in the stage of uniform wear can be changed by adjusting the frequency of discharge pulse. The electrical energy distributing rule of tool electrode section in RC circuit has been investigated under the influence of skin effect, and the law of spark location change has been summarized. The experimental studies demonstrate that different shapes of tool ends can be achieved by varying the pulse frequencies of discharge power supply. Additionally, a micro part of freeform surface feature with high precision and good surface quality has been successfully obtained by micro EDM through adopting the smooth surface after tool wear.
基金supported by the National Natural Science Foundation of China under Grant No.50577028the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20050487044the China Postdoctoral Science Foundation under Grant No.20080440931
文摘The skin effect in the reversely switched dynistor （RSD） devices is investigated in this paper. Based on the plasma bipolar drift model of the RSD, the current density distributions on the chip are simulated with considering the skin effect. The results indicate that the current density on the border can be several hundred to a thousand A/cm2 higher than that in the center of the chip. The skin effect becomes more prominent as the voltage increases and the inductance decreases in the main circuit. The phenomenon that most of a certain group of chips break over on the border has proved the existence of the skin effect.
基金Project supported by Hebei Provincial Natural Science Foundation of China(Grant Nos.A2012203174 and A2015203387)the National Natural Science Foundation of China(Grant Nos.10974169 and 11304270)
文摘The non-Hermitian skin effect breaks the conventional bulk–boundary correspondence and leads to non-Bloch topological invariants.Inspired by the fact that the topological protected zero modes are immune to perturbations,we construct a partner of a non-Hermitian system by getting rid of the non-Hermitian skin effect.Through adjusting the imbalance hopping,we find that the existence of zero-energy boundary states still dictate the bulk topological invariants based on the band-theory framework.Two non-Hermitian Su–Schrieffer–Heeger(SSH)models are used to illuminate the ideas.Specially,we obtain the winding numbers in analytical form without the introduction of the generalized Brillouin zone.The work gives an alternative method to calculate the topological invariants of non-Hermitian systems.
基金the National Natural Science Foundation of China(Grants No.11504143).
文摘We investigate novel features of three-dimensional non-Hermitian Weyl semimetals,paying special attention to the unconventional bulk-boundary correspondence.We use the non-Bloch Chern numbers as the tool to obtain the topological phase diagram,which is also confirmed by the energy spectra from our numerical results.It is shown that,in sharp contrast to Hermitian systems,the conventional(Bloch)bulk-boundary correspondence breaks down in non-Hermitian topological semimetals,which is caused by the non-Hermitian skin effect.We establish the non-Bloch bulk-boundary correspondence for non-Hermitian Weyl semimetals:the topological edge modes are determined by the non-Bloch Chern number of the bulk bands.Moreover,these topological edge modes can manifest as the unidirectional edge motion,and their signatures are consistent with the non-Bloch bulk-boundary correspondence.Our work establishes the non-Bloch bulk-boundary correspondence for non-Hermitian topological semimetals.
文摘In most studies of microstrip circuits, the majority of researchers assume that the microstrip structures studied have flat metallic conductors of finite widths but without thickness. But in reality these types of structures integrate metallic copper conductors of different thicknesses. If we neglect this thickness we introduce error in the electrical parameters of the microstrip structure, which affects the effective permittivity, the characteristic impedance, the adaptation of the circuit, the resonance frequency, etc. Given the importance of this parameter (thickness of the metal of micro rubon structures), rigorous electromagnetic modeling of the thick micro rubon line based on the skin effect phenomenon (In fact at high frequency the skin effect phenomenon occurs and the current only flows on the periphery of the conductor) has been proposed to improve the studied electric model and ensure the increase in the precision of the analysis method used: Wave concept iterative process. The good agreement between the simulated and published data justifies the improvement of the model.
基金supported by the National Key Research and Development Program of China(2023YFA1406704 and 2022YFA1405800)the start-up grant of IOP-CAS。
文摘The non-Hermitian skin effect is an iconic phenomenon characterized by the aggregation of eigenstates near the system boundaries in non-Hermitian systems.While extensively studied in one dimension,understanding the skin effect and extending the non-Bloch band theory to higher dimensions encounter a formidable challenge,primarily due to infinite lattice geometries or open boundary conditions.This work adopts a point-gap perspective and unveils that non-Hermitian skin effect in all spatial dimensions originates from point gaps.We introduce the concept of uniform spectra and reveal that regardless of lattice geometry,their energy spectra are universally given by the uniform spectra,even though their manifestations of skin modes may differ.Building on the uniform spectra,we demonstrate how to account for the skin effect with generic lattice cuts and establish the connections of skin modes across different geometric shapes via momentum-basis transformations.Our findings highlight the pivotal roles point gaps play,offering a unified understanding of the topological origin of non–Hermitian skin effect in all dimensions.
基金the LiaoNing Revitalization Talents Program(Grant No.XLYC1907033)the National Natural Science Foundation of China(Grant No.11905027)+1 种基金the Natural Science Foundation of Liaoning province(Grant No.2023-MS-072)Fundamental Research Funds for the Central Universities of Ministry of Education of China(Grant Nos.N2209005 and N2205015).
文摘We concentrate on the skin effects and topological properties in the multilayer non-Hermitian Su−Schrieffer−Heeger (SSH) structure, by taking into account the nonreciprocal couplings between the different sublattices in the unit cells. Following the detailed demonstration of the theoretical method, we find that in this system, the skin effects and topological phase transitions induced by nonreciprocal couplings display the apparent parity effect, following the increase of the layer number of this SSH structure. On the one hand, the skin effect is determined by the parity of the layer number of this SSH system, as well as the parity of the band index of the bulk states. On the other hand, for the topological edge modes, such an interesting parity effect can also be observed clearly. Next, when the parameter disorders are taken into account, the zero-energy edge modes in the odd-layer structures tend to be more robust, whereas the other edge modes are easy to be destroyed. In view of these results, it can be ascertained that the findings in this work promote to understand the influences of nonreciprocal couplings on the skin effects and topological properties in the multilayer SSH lattices.
基金C.H.Lee acknowledges support from Singapore NRF’s QEP2.0 grant(NRF2021-QEP2-02-P09)MOE Tier-1 grant(WBS:A-8000022-00-00)+1 种基金L.Li acknowledges support from National Natural Science Foundation of China(Grant No.12104519)the Guangdong Project(Grant No.2021QN02X073).
文摘This article reviews recent developments in the non-Hermitian skin effect(NHSE),particularly on its rich interplay with topology.The review starts off with a pedagogical introduction on the modified bulk-boundary correspondence,the synergy and hybridization of NHSE and band topology in higher dimensions,as well as,the associated topology on the complex energy plane such as spectral winding topology and spectral graph topology.Following which,emerging topics are introduced such as non-Hermitian criticality,dynamical NHSE phenomena,and the manifestation of NHSE beyond the traditional linear non-interacting crystal lattices,particularly its interplay with quantum many-body interactions.Finally,we survey the recent demonstrations and experimental proposals of NHSE.
文摘Background: Magnetic resonance image-guided radiation therapy (MR-IGRT) promises more precise and effective radiation treatments compared to conventional IGRT by using real-time on-board MR imaging. Under the influence of a magnetic field, however, secondary electrons exiting a surface can be forced in a circular path and re-enter the medium, resulting in dose increase at a beam-exit surface, called the electron return effect (ERE). The purpose of the study is to compare the exit skin dose computed by Monte Carlo dose calculation with measurements using an adult anthropomorphic phantom and to measure the effect of skin dose reduction by adding 1 cm-thick bolus. Method: The plan was compared with measurements using an adult anthropomorphic phantom combined with radiochromic films and thermoluminescent dosimeters. We also measured the skin dose reduction by adding 1 cm-thick bolus on the frontal surface of the phantom. Results: We found that 1 cm-thick bolus reduced the skin dose by up to 20% both in measurements and calculations. The plan was found to overestimate the measured skin dose by about 10% and there was no significant difference in the bolus effect between the breast skin and the skin (without breast attachment) doses. Conclusion: In conclusion, we confirmed the ERE effect on the anthropomorphic phantom under the magnetic field and the exit skin dose reduction by adding a bolus. Skin dose measurements using anthropomorphic phantom may be helpful to evaluate more realistic skin dose and the bolus effect in the magnetic field.
文摘In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' topical dose (52 μg/200 μl acetone ) of 7, 12-dimethylbenzanthracene (DMBA). To evaluate the anti-tumour initiating activity, BTP was topically applied twice a week for three weeks prior to DMBA application, followed by topical treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA) (5 μg/200 μl acetone, 2x/wk. ) as promoter. For evaluation of antitumor promoting activity, BTP was applied prior to each treatment of TPA. BTP application showed marked inhibitory effect as antitumour initiator as well as antitumour promoter in mouse skin medel of two-stage carcinogenesis. Since initiation involves genetic pathway and tumour promotion involves epigenetic pathway, it seems that BTP exerts its antitumorigenic effect by altering both genetic and epigenetic pathways
文摘We studied the effects of butyric acid (BA) on mouse skin tumorigenesis using chronicanimal bioassays. Topical application of BA immediately after each treatment with 12-0-te-t radecanoyl phorbol-13-acetate (TPA) promoter' inhi bi ted skint umors. The effect was depe n -dent on the dose of BA applied. BA showed no marked inhibitory effect on either skin tumorinitiation or complete tumorigenesis induced by dimet hyl benzant hracene (DMBA ). Si nce t u -mor promotion reportedly involves epigenetic events whereas tumor initiation or complete tu-morigenesis takes place through genetic pathways, it is Possible that BA exerts its antitumori-genic effects mainly by altering the epigenetic events responsible for tumor promotion. The re-sults of the study could further be used to study the mechanism of action and modification ofantitumorigenic effects of BA in combination with other substances
基金Supported by Natural Science Foundation of Sichuan Education Department(2008ZA033)
文摘[ Objective] This study aimed to investigate the biological effects of laser-induced mutation on fibrous roots of yellow skin onion. [ Method] Wet seeds of two yellow skin onion cultivars were irradiated by CO2 laser and He-Ne laser at three dosage levels separately. A randomized complete block design with three replications was adopted. The biological effects of laser-induced mutation on fibrous roots of Ll-generation yellow skin onion were investigated with biostatistics and physiological and biochemical methods. [Result] Significant variations in the biological effects caused by various laser treatments were observed in the length, quantity, fresh weight and activity of onion fibrous roots. Specifically, the variation in fibrous root length induced by different types of laser reached 5% significance level; significant variation was observed in fibrous roots of different onion cultivars induced by laser, while the variation among each treatment did not reach 5% sig- nifieance level ; the variation in fibrous root quantity induced by different dosage levels of laser reached 5% significance level ; laser radiation showed stimulating effect on root activity of onion. [ Conclusion] This study provided reference for laser-induced breeding of yellow skin onion.
基金supported by the Research Fund of the Erciyes University(TSD-09-1039)
文摘Epilepsy is a neurodegenerative disease that interrupts the normal electrical activity of the brain and promotes abnormal wiring in this organ.Epileptic seizures are often associated with significant changes in the functioning of the autonomic nervous system(ANS).
文摘A high peak power IPL system (Lumecca) was tested to determine the correlation between a high peak power and the successful treatment of pigmented and vascular lesions. Short pulse duration in the millisecond range and high peak power of 3.3 kW/cm<sup>2</sup> enabled selective and effective destruction, not only of pigment, but also of vessels in a comparable manner to a pulsed dye laser. Only one treatment session at a low fluence (8 - 16 J/cm<sup>2</sup>) was sufficient to achieve the desired results.
文摘The skin is a formidable physical and biological barrier which communicates continuously with the outside of the body. And the stratum corneum, the outermost layer of human epidermis, plays a central role in the interaction between the cutaneous tissue and the external environment. The horny layer, and more generally the whole skin layers, avoid the penetration of harmful exogenous agents, produce molecules named anti-microbial peptides which impact the composition of the cutaneous microbiota, regulate the internal corporal temperature, avoid the water loss from the inside of the body and constitute an incredible efficient anti-oxidant network. Nevertheless, nowadays, the skin is more and more solicited by the different elements of the cutaneous exposome, including atmospheric pollution and solar radiations, which can cause a dramatic acceleration of the skin ageing process. As a consequence, due to the multifunctional protective role of the skin, during the recent decade the cosmetic industry invested massively in the development of new raw materials and end-products (dermo-cosmetics) able to preserve an optimal state of the skin regarding the external environment. Based on their physical-chemical properties thermal spring waters, which are extremely rich in inorganics ions, are interesting and powerful candidates to be part, as integral component, of new efficient dermo-cosmetic formulations dedicated to protect the skin from the external stimuli. The aim of the present work was to investigate and characterize the activity of Jonzac thermal spring water on the skin. Using different models, we proved for the first time that Jonzac thermal spring water reinforces the barrier function of the skin by modulating the expression of key markers including filaggrin and human beta defensin 2 on ex vivo human skin. The ex vivo and in vivo hydration activity, by Raman spectroscopy and corneometry respectively, has been also demonstrated. We have also shown that Jonzac thermal spring water ameliorates significantly the cutaneous microrelief in vivo. To conclude, we characterize the soothing effect of Jonzac thermal spring water by the analysis of histamine release in Substance P treated skin explants and by measuring the redness of the skin following UV exposure of the skin in vivo. We observed that both parameters decreased following a preventive treatment of the skin with Jonzac thermal spring water. Taken together our results indicate that Jonzac thermal spring water is a promising and powerful dermo-cosmetic which can be used to preserve an optimal state of the cutaneous tissue.
基金Project supported by the National Basic Research Program of China(973 Program)(No.2014CB744802)the National Natural Science Foundation of China(No.11772194)
文摘As the Reynolds number increases, the skin friction has been identified as the dominant drag in many practical applications. In the present paper, the effects of the Reynolds number on the mean skin friction decomposition in turbulent channel flows up to Reτ= 5 200 are investigated based on two different methods, i.e., the FukagataIwamoto-Kasagi(FIK) identity(FUKAGATA, K., IWAMOTO, K., and KASAGI, N.Contribution of Reynolds stress distribution to the skin friction in wall-bounded flows.Physics of Fluids, 14(11), L73–L76(2002)) and the Renard-Deck(RD) identity(DECK,S., RENARD, N., LARAUFIE, R., and WEISS, P.′E. Large-scale contribution to mean wall shear stress in high-Reynolds-number flat-plate boundary layers up to Reθ= 13 650.Journal of Fluid Mechanics, 743, 202–248(2014)). The direct numerical simulation(DNS) data provided by Lee and Moser(LEE, M. and MOSER, R. D. Direct numerical simulation of turbulent channel flow up to Reτ≈ 5 200. Journal of Fluid Mechanics,774, 395–415(2015)) are used. For these two skin friction decomposition methods, their decomposed constituents are discussed and compared for different Reynolds numbers.The integrands of the decomposed constituents are locally analyzed across the boundary layer to assess the actions associated with the inhomogeneity and multi-scale nature of turbulent motion. The scaling of the decomposed constituents and their integrands are presented. In addition, the boundary layer is divided into three sub-regions to evaluate the contributive proportion of each sub-region with an increase in the Reynolds number.
基金Supported by Shanghai Science and Technology Supporting Program(08DZ1203500)City University of Hong Kong(7002004)+1 种基金Shanghai Local University Fund(071605124)Undergraduates Education Fund for University of Shanghai
文摘The mathematic model of heat transfer through ventilated double glazing was verified with the measured data,which were from a test chamber equipped with glass face temperature,solar radiation,ambient temperature,and wind speed measurement facility.After the model validation,the double-skin facade assessment was carried out through simulation with ESP-r software integrating thermal simulation and air low net work module.The air flow situation in the air gap was analyzed on the basis of the hourly air velocity simulation data within typical winter week,summer week,spring week and autumn week.The differences of chimney effect in different seasons were discussed,and the thermal loads resulted from the ventilated and unventilated double skin facade were presented.
