An uncommon fractal construction method is applied in the microwave element design. A novel fractal defected ground structure （DGS） based on micro electro-mechanical system （MEMS） is proposed. The size of this nov...An uncommon fractal construction method is applied in the microwave element design. A novel fractal defected ground structure （DGS） based on micro electro-mechanical system （MEMS） is proposed. The size of this novel fractal DGS can achieve 86% size reduction compared with the conventional dumbbell type DGS. This novel fractal DGS is used in the miniaturization design of L-band microstrip antenna array. The simulation result shows that this novel fractal DGS can effectively reduce the mutual coupling between the antenna elements, so it is helpful to the miniaturization of microstrip array, namely the approximately same gain value can be achieved with the shorter distance between elements.展开更多
Diabetic retinopathy is a prominent cause of blindness in adults,with early retinal ganglion cell loss contributing to visual dysfunction or blindness.In the brain,defects inγ-aminobutyric acid synaptic transmission ...Diabetic retinopathy is a prominent cause of blindness in adults,with early retinal ganglion cell loss contributing to visual dysfunction or blindness.In the brain,defects inγ-aminobutyric acid synaptic transmission are associated with pathophysiological and neurodegenerative disorders,whereas glucagon-like peptide-1 has demonstrated neuroprotective effects.However,it is not yet clear whether diabetes causes alterations in inhibitory input to retinal ganglion cells and whether and how glucagon-like peptide-1 protects against neurodegeneration in the diabetic retina through regulating inhibitory synaptic transmission to retinal ganglion cells.In the present study,we used the patch-clamp technique to recordγ-aminobutyric acid subtype A receptor-mediated miniature inhibitory postsynaptic currents in retinal ganglion cells from streptozotocin-induced diabetes model rats.We found that early diabetes(4 weeks of hyperglycemia)decreased the frequency of GABAergic miniature inhibitory postsynaptic currents in retinal ganglion cells without altering their amplitude,suggesting a reduction in the spontaneous release ofγ-aminobutyric acid to retinal ganglion cells.Topical administration of glucagon-like peptide-1 eyedrops over a period of 2 weeks effectively countered the hyperglycemia-induced downregulation of GABAergic mIPSC frequency,subsequently enhancing the survival of retinal ganglion cells.Concurrently,the protective effects of glucagon-like peptide-1 on retinal ganglion cells in diabetic rats were eliminated by topical administration of exendin-9-39,a specific glucagon-like peptide-1 receptor antagonist,or SR95531,a specific antagonist of theγ-aminobutyric acid subtype A receptor.Furthermore,extracellular perfusion of glucagon-like peptide-1 was found to elevate the frequencies of GABAergic miniature inhibitory postsynaptic currents in both ON-and OFF-type retinal ganglion cells.This elevation was shown to be mediated by activation of the phosphatidylinositol-phospholipase C/inositol 1,4,5-trisphosphate receptor/Ca2+/protein kinase C signaling pathway downstream of glucagon-like peptide-1 receptor activation.Moreover,multielectrode array recordings revealed that glucagon-like peptide-1 functionally augmented the photoresponses of ON-type retinal ganglion cells.Optomotor response tests demonstrated that diabetic rats exhibited reductions in visual acuity and contrast sensitivity that were significantly ameliorated by topical administration of glucagon-like peptide-1.These results suggest that glucagon-like peptide-1 facilitates the release ofγ-aminobutyric acid onto retinal ganglion cells through the activation of glucagon-like peptide-1 receptor,leading to the de-excitation of retinal ganglion cell circuits and the inhibition of excitotoxic processes associated with diabetic retinopathy.Collectively,our findings indicate that theγ-aminobutyric acid system has potential as a therapeutic target for mitigating early-stage diabetic retinopathy.Furthermore,the topical administration of glucagon-like peptide-1 eyedrops represents a non-invasive and effective treatment approach for managing early-stage diabetic retinopathy.展开更多
Monolithic macroporous Pt/CeO2/Al2O3 catalysts were prepared using concentrated emulsions synthesis route, and the obtained samples were characterized with SEM, TG, TEM, XRD and TPR techniques. These monolithic cataly...Monolithic macroporous Pt/CeO2/Al2O3 catalysts were prepared using concentrated emulsions synthesis route, and the obtained samples were characterized with SEM, TG, TEM, XRD and TPR techniques. These monolithic catalysts were applied to water gas shift （WGS） reaction in reformed gases. The SEM and TEM results indicated that the monoliths possessed macroporosity, and that the platinum particles homogeneously dispersed on the supports with the particle size in the range of 1-2 nm. The reducibility of the catalysts was characterized by TPR method, and it was shown that the monolithic PtOx/CeO2/Al2O3 exhibited the similar reducibility property to that of the particle PtOx/CeO2 reported in literatures. The CO conversion over the monolithic catalysts is higher than that over micro-reactor catalysts for WGS reaction in the reformed gases conditions, indicating that the monolithic macroporous catalysts is a potential new route for miniaturization of WGS reactor.展开更多
Based on previous work, a novel Frequency Selective Surface (FSS) consisting of two metallic layers is proposed. The first layer is inductive-designed to generate the band-pass performance, while the second layer is c...Based on previous work, a novel Frequency Selective Surface (FSS) consisting of two metallic layers is proposed. The first layer is inductive-designed to generate the band-pass performance, while the second layer is capacitive-designed so that the miniaturization characteristic can be further improved. As a result, compared with the traditional single-layer structure, the profile of the FSS proposed is relatively small with the cell’s dimension only 0.0814λ × 0.0814λ. Moreover, the structure’s stability corresponding to waves of different polarizations and incident angles are also testified, which ensures the practicability of the proposed structure.展开更多
Since the discovery of mesoporous silica in 1990s,there have been numerous mesoporous silica-based nanomaterials developed for catalytic applications,aiming at enhanced catalytic activity and stability.Recently,there ...Since the discovery of mesoporous silica in 1990s,there have been numerous mesoporous silica-based nanomaterials developed for catalytic applications,aiming at enhanced catalytic activity and stability.Recently,there have also been considerable interests in endowing them with hierarchical porosities to overcome the diffusional limitation for those with long unimodal channels.Present processes of making mesoporous silica largely rely on chemical sources which are relatively expensive and impose environmental concerns on their processes.In this regard,it is desirable to develop hierarchical silica supports from natural minerals.Herein,we present a series of work on surface reconstruction,modification,and functionalization to produce diatomite-based catalysts with original morphology and macro-meso-micro porosities and to test their suitability as catalyst supports for both liquid-and gas-phase reactions.Two wet-chemical routes were developed to introduce mesoporosity to both amorphous and crystalline diatomites.Importantly,we have used computational modeling to affirm that the diatomite morphology can improve catalytic performance based on fluid dynamics simulations.Thus,one could obtain this type of catalysts from numerous natural diatoms that have inherently intricate morphologies and shapes in micrometer scale.In principle,such catalytic nanocomposites acting as miniaturized industrial catalysts could be employed in microfluidic reactors for process intensification.展开更多
Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties sim...Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties simultaneously remains a difficult challenge due to their mutually restrictive relationship.Here 0.5Pb(Ni_(1/3)Nb_(2/3))O_(3)-0.5Pb(Zr_(0.3)Ti_(0.7))O_(3) piezoceramic with tetragonal(T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions.The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of P_(s),restrict domain wall motion and improve Q_(m).At the same time,the substituted Mn ions will introduce local random field,destroying the long-range or-dering of ferroelectric domain and reducing domain size.The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d_(33).Guided by this strategy,Q_(m) has increased by more than 10 times and d_(33) has only decreased by about 25%.The optimized electromechanical performance with Q_(m)=822,d_(33)=502 pC/N,k_(p)=0.55 and tanδ=0.0069 can be obtained in the present study.展开更多
Miniaturization and compact printed planar monopole antenna coplanar Waveguide CPW/microstrip feed line three half semi-circular （3HSC） with similar ground plane is presented, design, simulation, fabrication and tes...Miniaturization and compact printed planar monopole antenna coplanar Waveguide CPW/microstrip feed line three half semi-circular （3HSC） with similar ground plane is presented, design, simulation, fabrication and tested experimentally for Ultra-Wideband （UWB） eommnnication application especially for WLAN and HIPERLAN/2 WLAN. The antenna design has a far from the traditional antennas such as a rectangular, circular, elliptical etc. Generating original planar antenna has been investigated to be an effect the combine geometry shapes of the radiation element part with the same geometry shapes of the slots in the ground plane. The simulation and measuring results have a good agreement, large bandwidth and radiation pattern behavior an omni-directional with stable gain has been obtained.展开更多
基金supported by the 11th Five-Year Plan under Grant No. 11001030203
文摘An uncommon fractal construction method is applied in the microwave element design. A novel fractal defected ground structure （DGS） based on micro electro-mechanical system （MEMS） is proposed. The size of this novel fractal DGS can achieve 86% size reduction compared with the conventional dumbbell type DGS. This novel fractal DGS is used in the miniaturization design of L-band microstrip antenna array. The simulation result shows that this novel fractal DGS can effectively reduce the mutual coupling between the antenna elements, so it is helpful to the miniaturization of microstrip array, namely the approximately same gain value can be achieved with the shorter distance between elements.
基金supported by the National Natural Science Foundation of China,Nos.32070989(to YMZ),31872766(to YMZ),81790640(to XLY),and 82070993(to SJW)the grant from Sanming Project of Medicine in Shenzhen,No.SZSM202011015(to XLY)。
文摘Diabetic retinopathy is a prominent cause of blindness in adults,with early retinal ganglion cell loss contributing to visual dysfunction or blindness.In the brain,defects inγ-aminobutyric acid synaptic transmission are associated with pathophysiological and neurodegenerative disorders,whereas glucagon-like peptide-1 has demonstrated neuroprotective effects.However,it is not yet clear whether diabetes causes alterations in inhibitory input to retinal ganglion cells and whether and how glucagon-like peptide-1 protects against neurodegeneration in the diabetic retina through regulating inhibitory synaptic transmission to retinal ganglion cells.In the present study,we used the patch-clamp technique to recordγ-aminobutyric acid subtype A receptor-mediated miniature inhibitory postsynaptic currents in retinal ganglion cells from streptozotocin-induced diabetes model rats.We found that early diabetes(4 weeks of hyperglycemia)decreased the frequency of GABAergic miniature inhibitory postsynaptic currents in retinal ganglion cells without altering their amplitude,suggesting a reduction in the spontaneous release ofγ-aminobutyric acid to retinal ganglion cells.Topical administration of glucagon-like peptide-1 eyedrops over a period of 2 weeks effectively countered the hyperglycemia-induced downregulation of GABAergic mIPSC frequency,subsequently enhancing the survival of retinal ganglion cells.Concurrently,the protective effects of glucagon-like peptide-1 on retinal ganglion cells in diabetic rats were eliminated by topical administration of exendin-9-39,a specific glucagon-like peptide-1 receptor antagonist,or SR95531,a specific antagonist of theγ-aminobutyric acid subtype A receptor.Furthermore,extracellular perfusion of glucagon-like peptide-1 was found to elevate the frequencies of GABAergic miniature inhibitory postsynaptic currents in both ON-and OFF-type retinal ganglion cells.This elevation was shown to be mediated by activation of the phosphatidylinositol-phospholipase C/inositol 1,4,5-trisphosphate receptor/Ca2+/protein kinase C signaling pathway downstream of glucagon-like peptide-1 receptor activation.Moreover,multielectrode array recordings revealed that glucagon-like peptide-1 functionally augmented the photoresponses of ON-type retinal ganglion cells.Optomotor response tests demonstrated that diabetic rats exhibited reductions in visual acuity and contrast sensitivity that were significantly ameliorated by topical administration of glucagon-like peptide-1.These results suggest that glucagon-like peptide-1 facilitates the release ofγ-aminobutyric acid onto retinal ganglion cells through the activation of glucagon-like peptide-1 receptor,leading to the de-excitation of retinal ganglion cell circuits and the inhibition of excitotoxic processes associated with diabetic retinopathy.Collectively,our findings indicate that theγ-aminobutyric acid system has potential as a therapeutic target for mitigating early-stage diabetic retinopathy.Furthermore,the topical administration of glucagon-like peptide-1 eyedrops represents a non-invasive and effective treatment approach for managing early-stage diabetic retinopathy.
基金supported by the Ministry of Sciences and Technology of China (863 programs, No 2006AA05Z115 and 2007AA05Z104)the National Natural Science Foundation of China (No. 20976121)
文摘Monolithic macroporous Pt/CeO2/Al2O3 catalysts were prepared using concentrated emulsions synthesis route, and the obtained samples were characterized with SEM, TG, TEM, XRD and TPR techniques. These monolithic catalysts were applied to water gas shift （WGS） reaction in reformed gases. The SEM and TEM results indicated that the monoliths possessed macroporosity, and that the platinum particles homogeneously dispersed on the supports with the particle size in the range of 1-2 nm. The reducibility of the catalysts was characterized by TPR method, and it was shown that the monolithic PtOx/CeO2/Al2O3 exhibited the similar reducibility property to that of the particle PtOx/CeO2 reported in literatures. The CO conversion over the monolithic catalysts is higher than that over micro-reactor catalysts for WGS reaction in the reformed gases conditions, indicating that the monolithic macroporous catalysts is a potential new route for miniaturization of WGS reactor.
文摘Based on previous work, a novel Frequency Selective Surface (FSS) consisting of two metallic layers is proposed. The first layer is inductive-designed to generate the band-pass performance, while the second layer is capacitive-designed so that the miniaturization characteristic can be further improved. As a result, compared with the traditional single-layer structure, the profile of the FSS proposed is relatively small with the cell’s dimension only 0.0814λ × 0.0814λ. Moreover, the structure’s stability corresponding to waves of different polarizations and incident angles are also testified, which ensures the practicability of the proposed structure.
基金the financial support provided by the National Research Foundation (NRF), Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) programpartially funded by the National University of Singapore under its Flagship Green Energy Program (GEP), Agency for Science, Technology and Research (A*STAR) under its Low Carbon Energy Research Funding Initiative (LCER-FI)Chongqing Science and Technology Research and Development Base Construction Project (cstc2013gjhz0029)
文摘Since the discovery of mesoporous silica in 1990s,there have been numerous mesoporous silica-based nanomaterials developed for catalytic applications,aiming at enhanced catalytic activity and stability.Recently,there have also been considerable interests in endowing them with hierarchical porosities to overcome the diffusional limitation for those with long unimodal channels.Present processes of making mesoporous silica largely rely on chemical sources which are relatively expensive and impose environmental concerns on their processes.In this regard,it is desirable to develop hierarchical silica supports from natural minerals.Herein,we present a series of work on surface reconstruction,modification,and functionalization to produce diatomite-based catalysts with original morphology and macro-meso-micro porosities and to test their suitability as catalyst supports for both liquid-and gas-phase reactions.Two wet-chemical routes were developed to introduce mesoporosity to both amorphous and crystalline diatomites.Importantly,we have used computational modeling to affirm that the diatomite morphology can improve catalytic performance based on fluid dynamics simulations.Thus,one could obtain this type of catalysts from numerous natural diatoms that have inherently intricate morphologies and shapes in micrometer scale.In principle,such catalytic nanocomposites acting as miniaturized industrial catalysts could be employed in microfluidic reactors for process intensification.
基金financially supported by the National Natural Science Foundation of China(Nos.52172181 and22105017).
文摘Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties simultaneously remains a difficult challenge due to their mutually restrictive relationship.Here 0.5Pb(Ni_(1/3)Nb_(2/3))O_(3)-0.5Pb(Zr_(0.3)Ti_(0.7))O_(3) piezoceramic with tetragonal(T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions.The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of P_(s),restrict domain wall motion and improve Q_(m).At the same time,the substituted Mn ions will introduce local random field,destroying the long-range or-dering of ferroelectric domain and reducing domain size.The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d_(33).Guided by this strategy,Q_(m) has increased by more than 10 times and d_(33) has only decreased by about 25%.The optimized electromechanical performance with Q_(m)=822,d_(33)=502 pC/N,k_(p)=0.55 and tanδ=0.0069 can be obtained in the present study.
文摘Miniaturization and compact printed planar monopole antenna coplanar Waveguide CPW/microstrip feed line three half semi-circular （3HSC） with similar ground plane is presented, design, simulation, fabrication and tested experimentally for Ultra-Wideband （UWB） eommnnication application especially for WLAN and HIPERLAN/2 WLAN. The antenna design has a far from the traditional antennas such as a rectangular, circular, elliptical etc. Generating original planar antenna has been investigated to be an effect the combine geometry shapes of the radiation element part with the same geometry shapes of the slots in the ground plane. The simulation and measuring results have a good agreement, large bandwidth and radiation pattern behavior an omni-directional with stable gain has been obtained.
