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Sökning: WFRF:(Bao Lei)

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2.
  • Kristanl, Matej, et al. (författare)
  • The Seventh Visual Object Tracking VOT2019 Challenge Results
  • 2019
  • Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
  • Konferensbidrag (refereegranskat)abstract
    • The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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6.
  • Bao, Lei, et al. (författare)
  • A scheme for joint quantization, error protection and feedback control over noisy channels
  • 2007
  • Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. - : IEEE. - 9781424409884 ; , s. 2456-2461
  • Konferensbidrag (refereegranskat)abstract
    • We study a closed-loop scalar control system with feedback transmitted over a discrete noisy channel. For this problem, we propose a joint design of the state measurement quantization, protection against channel errors, and control. The goal is to minimize a linear quadratic cost function over a finite horizon. In particular we focus on a special case where we verify that certainty equivalence holds, and for this case we design joint source-channel encoder and decoder/estimator pairs. The proposed algorithm leads to a practically feasible design of time-varying non-uniform quantization and control. Numerical results demonstrate the promising performance obtained by employing the proposed iterative optimization algorithm.
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7.
  • Bao, Lei, 1976- (författare)
  • Control over Low-Rate Noisy Channels
  • 2009
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Networked embedded control systems are present almost everywhere. A recent trendis to introduce radio communication in these systems to increase mobility and flex-ibility. Network nodes, such as the sensors, are often simple devices with limitedcomputing and transmission power and low storage capacity, so an important prob-lem concerns how to optimize the use of resources to provide sustained overall sys-tem performance. The approach to this problem taken in the thesis is to analyzeand design the communication and control application layers in an integrated man-ner. We focus in particular on cross-layer design techniques for closed-loop controlover non-ideal communication channels, motivated by future control systems withvery low-rate and highly quantized sensor communication over noisy links. Severalfundamental problems in the design of source–channel coding and optimal controlfor these systems are discussed.The thesis consists of three parts. The first and main part is devoted to the jointdesign of the coding and control for linear plants, whose state feedback is trans-mitted over a finite-rate noisy channel. The system performance is measured by afinite-horizon linear quadratic cost. We discuss equivalence and separation proper-ties of the system, and conclude that although certainty equivalence does not holdin general it can still be utilized, under certain conditions, to simplify the overalldesign by separating the estimation and the control problems. An iterative opti-mization algorithm for training the encoder–controller pairs, taking channel errorsinto account in the quantizer design, is proposed. Monte Carlo simulations demon-strate promising improvements in performance compared to traditional approaches.In the second part of the thesis, we study the rate allocation problem for statefeedback control of a linear plant over a noisy channel. Optimizing a time-varyingcommunication rate, subject to a maximum average-rate constraint, can be viewedas a method to overcome the limited bandwidth and energy resources and to achievebetter overall performance. The basic idea is to allow the sensor and the controllerto communicate with a higher data rate when it is required. One general obstacle ofoptimal rate allocation is that it often leads to a non-convex and non-linear problem.We deal with this challenge by using high-rate theory and Lagrange duality. It isshown that the proposed method gives a good performance compared to some otherrate allocation schemes.In the third part, encoder–controller design for Gaussian channels is addressed.Optimizing for the Gaussian channel increases the controller complexity substan-tially because the channel output alphabet is now infinite. We show that an efficientcontroller can be implemented using Hadamard techniques. Thereafter, we proposea practical controller that makes use of both soft and hard channel outputs.
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8.
  • Bao, Lei, et al. (författare)
  • Encoder-controller design for control over the binary-input Gaussian channel
  • 2010
  • Ingår i: IEEE International Symposium on Spread Spectrum Techniques and Applications. - : IEEE. - 9781424460151 ; , s. 23-28
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we consider the problem of the joint optimization of encoder-controller for closed-loop control with state feedback over a binary-input Gaussian channel (BGC). The objective is to minimize the expected linear quadratic cost over a finite horizon. Thisencoder-controller optimization problem is hard in general, mostly because of the curse of dimensionality. The result of this paper is a synthesis technique for a computationally feasible suboptimal controller which exploits both the soft and hard information of thechannel outputs. The proposed controller is efficient in the sense that it embraces measurement quantization, error protection and control over a finite-input infinite-output noisy channel. How to effectively implement this controller is also addressed in the paper. In particular, this is done by using Hadamard techniques. Numerical experiments are carried out to verify the promising gain offered by the combined controller, in comparison to the hard-information-based controller.
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9.
  • Bao, Lei, et al. (författare)
  • Encoder-decoder design for event-triggered feedback control over bandlimited channels
  • 2006
  • Ingår i: 2006 American Control Conference. - : IEEE. - 1424402093 ; , s. 4183-4188
  • Konferensbidrag (refereegranskat)abstract
    • Bandwidth limitations and energy constraints set severe restrictions on the design of control systems that utilize wireless sensor and actuator networks. It is common in these systems that a sensor node needs not be continuously monitored, but communicates to the controller only at certain instances when it detects a disturbance event. In this paper, such a scenario is studied and particular emphasis is on efficient utilization of the shared communication resources. Encoder-decoder design for an event-based control system with the plant affected by pulse disturbances is considered. A new iterative procedure is proposed which can jointly optimize encoder-decoder pairs for a certainty equivalent controller. The goal is to minimize a design criterion, in particular, a linear quadratic cost over a finite horizon. The algorithm leads to a feasible design of time-varying non-uniform encoder-decoder pairs. Numerical results demonstrate significant improvements in performance compared to a system using uniform quantization.
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10.
  • Bao, Lei (författare)
  • Immunomodulation and immunopathogenesis in autoimmune disease with emphasis on autoimmune neuritis and arthritis
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Experimental autoimmune neuritis (EAN) and arthritis are CD4+ T cell mediated autoimmune animal models for the study of immunomodulation and immunopathogenesis of human Guillain-Barré syndrome (GBS) and rheumatoid arthritis (RA). Inflammatory cell infiltration and cytokine production in the target organs are characteristic features of both diseases, suggesting a role of cytokine production in the pathogenesis. A significant reduction in the incidence and severity of EAN and a delayed time of onset of EAN were found in IL-12 deficient (IL-12-/-), as compared to wild type mice. The clinical symptoms were associated with a reduced IFN-gamma and TNF-alpha, while enhanced IL-4 production in the sciatic nerve as well as significantly suppressed levels of anti-PO peptide IgG2b antibody in serum suggested that IL-12 has a major role in the initiation, enhancement and perpetuation of pathogenic events in EAN by promoting a Th1 cell-mediated immune response and suppressing the Th2 response. These results demonstrate that IIL-12 may play a critical role in the pathogenesis of EAN. Tumor necrosis factor receptor I (TNFR I) is thought to mediate the majority of TNF activities. When administered soluble TNFR I (sTNFR I) to mice immunized with PO peptide the severity and the duration of EAN were decreased. This was accompanied in vitro by a marked reduction in antigen-specific T cell proliferation and IFN-gamma synthesis by spleen cells in sTNFR I treated mice. Immunohistochemical analysis revealed a strong decrease in the number of infiltrating macrophages, CD4+ T cells and CD8+ T cells in the sciatic nerve. These data directly demonstrate a pivotal role for TNF in the development of EAN and also suggest that sTNFR I may have a therapeutic potential in human GBS. CC chemokine receptor 5 deficient (CCR5-/-) mice showed a significant reduction in the incidence of collagen-induced arthritis in comparison to wild-type (CCR5+/+) mice. However, the severity score once they developed arthritis showed clinical features similar to wild-type mice. There were significantly lower levels of antibodies against CH in CCR5-/- mice compared to wild- type mice, especially IgG2a and IgG2b, and obviously higher levels of EL10 in CCR5-/- mice. There was overproduction of MIP-1beta in serum and culture supernatant of spleen cells in CCR5 deficient mice after CH-immunization that might partly have contributed to the severity of arthritis. Our results indicate that CCR5 plays a role in the pathogenesis of arthritis, but its role can probably be substituted by other factors. Changes of glia and cytokine expression were found in the spinal cord of adjuvantinduced arthritic (AIA) rats. Macroglia and MHC class 11 immunostaining were enhanced, and the numbers and immunostaining intensity of astrocytes expressing GFAP were increased. Using in situ hybridization and immunohistochemical methods, both mRNA and protein levels of IL-1beta, IL-6 and TNF-alpha were significantly increased in the spinal cord of arthritic rats. Higher levels of cytokine expression were noted in reactive astrocytes and microglia.
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11.
  • Bao, Lei, et al. (författare)
  • Iterative encoder-controller design based on approximate dynamic programming
  • 2010
  • Ingår i: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC.
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we study the iterative optimization of the encoder-controller pair for closed-loop control of a multi-dimensional plant over a noisy discrete memoryless channel. With the objective to minimize the expected linear quadratic cost over a finite horizon, we propose a joint design of the sensor measurement quantization, channel error protection, and optimal controller actuation. It was shown in our previous work that despite this optimization problem is known to be hard in general, an iterative design procedure can be derived to obtain a local optimal solution. However, in the vector case, optimizing the encoder for a fixed controller is in general not practically feasible due to the curse of dimensionality. In this paper, we propose a novel approach that uses the approximate dynamic programming (ADP) to implement a computationally feasible encoder updating policy with promising performance. Especially, we introduce encoder updating rules adopting the rollout approach. Numerical experiments are carried out to demonstrate the performance obtained by employing the proposed iterative design procedure and to compare it with other relevant schemes.
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12.
  • Bao, Lei, et al. (författare)
  • Iterative Encoder-Controller Design for Feedback Control Over Noisy Channels
  • 2011
  • Ingår i: IEEE Transactions on Automatic Control. - : IEEE. - 0018-9286 .- 1558-2523. ; 56:2, s. 265-278
  • Tidskriftsartikel (refereegranskat)abstract
    • We study a closed-loop control system with state feedback transmitted over a noisy discrete memoryless channel. With the objective to minimize the expected linear quadratic cost over a finite horizon, we propose a joint design of the sensor measurement quantization, channel error protection, and controller actuation. It is argued that despite that this encoder-controller optimization problem is known to be hard in general, an iterative design procedure can be derived in which the controller is optimized for a fixed encoder, then the encoder is optimized for a fixed controller, etc. Several properties of such a scheme are discussed. For a fixed encoder, we study how to optimize the controller given that full or partial side-information is available at the encoder about the symbols received at the controller. It is shown that the certainty equivalence controller is optimal when the encoder is optimal and has full side-information. For a fixed controller, expressions for the optimal encoder are given and implications are discussed for the special cases when process, sensor, or channel noise is not present. Numerical experiments are carried out to demonstrate the performance obtained by employing the proposed iterative design procedure and to compare it with other relevant schemes.
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13.
  • Bao, Lei, et al. (författare)
  • On Iterative System Design and Separation in Control Over Noisy Channels
  • 2008
  • Ingår i: IFAC World Congress, Volume 17, Part 1. - : IFAC.
  • Konferensbidrag (refereegranskat)abstract
    • We study a closed-loop control system with feedback transmitted over a noisy discrete memoryless channel. We design encoder-controller pairs that jointly optimize the sensor measurement quantization, protection against channel errors, and control. The designgoal is to minimize an expected linear quadratic cost over a finite horizon. As a result of deriving optimality criteria for this problem, we present new results on the validity of theseparation principle subject to certain assumptions. More precisely, we show that the certainty equivalence controller is optimal when the encoder is optimal and has full side-information about the symbols received at the controller. We then use this result to formulate tractable design criteria in the general case. Finally, numerical experiments are carried out to demonstrate the performance obtained by various design methods. 
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14.
  • Bao, Lei, et al. (författare)
  • On optimal system design for feedback control over noisy channels
  • 2007
  • Ingår i: 2007 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY PROCEEDINGS, VOLS 1-7. - : IEEE. - 9781424413973 ; , s. 2486-2490
  • Konferensbidrag (refereegranskat)abstract
    • We study a closed-loop multivariable control system with sensor feedback transmitted over a discrete noisy channel. For this problem, we propose a joint design of the state measurement quantization, protection against channel errors, and control. The proposed algorithm leads to a practically feasible design of time-varying non-uniform encoding and control. Numerical results demonstrate the performance obtained by employing the proposed iterative optimization algorithm.
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15.
  • Bao, Lei, et al. (författare)
  • On rate allocation for multiple plants in a networked control system
  • 2012
  • Ingår i: 2012 American Control Conference (ACC). - : IEEE Computer Society. - 9781457710957 ; , s. 2024-2029
  • Konferensbidrag (refereegranskat)abstract
    • The problem of allocating communication resources to multiple plants in a networked control system is investigated. In the presence of a shared communication medium, a total transmission rate constraint is imposed. For the purpose of optimizing the rate allocation to the plants over a finite horizon, two objective functions are considered. The first one is a single-objective function, and the second one is a multi-objective function. Because of the difficulty to derive the closed-form expression of these functions, which depend on the instantaneous communication rate, an approximation is proposed by using high-rate quantization theory. It is shown that the approximate objective functions are convex in the region of interest both in the scalar case and in the multi-objective case. This allows to establish a linear control policy given by the classical linear quadratic Gaussian theory as function of the channel. Based on this result, a new complex relation between the control performance and the channel error probability is characterized.
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  • Bao, Lei, et al. (författare)
  • Optimized Rate Allocation for State Estimation over Noisy Channels
  • 2009
  • Ingår i: 2009 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY. - NEW YORK : IEEE. ; , s. 2684-2688
  • Konferensbidrag (refereegranskat)abstract
    • Optimal rate allocation in a networked control system with limited communication resources is instrumental to achieve satisfactory overall performance. In this paper, a practical rate allocation technique for state estimation in linear dynamic systems over a noisy channel is proposed. The method consists of two steps: (i) the overall distortion is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize the overall distortion is solved by using Lagrange duality. Monte Carlo simulations illustrate the proposed scheme, which is shown to have good performance when compared to arbitrarily selected rate allocations.
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18.
  • Bao, Lei, et al. (författare)
  • Optimized rate allocation for state feedback control over noisy channels
  • 2009
  • Ingår i: Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. Proceedings of the 48th IEEE Conference on. - : IEEE. - 9781424438716 ; , s. 573-578
  • Konferensbidrag (refereegranskat)abstract
    • Optimal rate allocation in a networked control system with highly limited communication resources is instrumental to achieve satisfactory overall performance. In this paper, we propose a rate allocation technique for state feedback control in linear dynamic systems over a noisy channel. Our method consists of two steps: (i) the overall distortion is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize the overall distortion is solved. We show that a non-uniform quantization is in general the best strategy for state feedback control over noisy channels. Monte Carlo simulations illustrate the proposed scheme, which is shown to have good performance compared to arbitrarily selected rate allocations.
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19.
  • Bao, Lei, et al. (författare)
  • Rate Allocation for Quantized Control Over Binary Symmetric Channels
  • 2012
  • Ingår i: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 60:6, s. 3188-3202
  • Tidskriftsartikel (refereegranskat)abstract
    • Utility maximization in networked control systems (NCSs) is difficult in the presence of limited sensing and communication resources. In this paper, a new communication rate optimization method for state feedback control over a noisy channel is proposed. Linear dynamic systems with quantization errors, limited transmission rate, and noisy communication channels are considered. The most challenging part of the optimization is that no closed-form expressions are available for assessing the performance and the optimization problem is nonconvex. The proposed method consists of two steps: (i) the overall NCS performance measure is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize a weighted quadratic objective function is solved. The proposed method is applied to the problem of state feedback control and the problem of state estimation. Monte Carlo simulations illustrate the performance of the proposed rate allocation. It is shown numerically that the proposed method has better performance when compared to arbitrarily selected rate allocations. Also, it is shown that in certain cases nonuniform rate allocation can outperform the uniform rate allocation, which is commonly considered in quantized control systems, for feedback control over noisy channels.
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20.
  • Bao, Lei, et al. (författare)
  • Rate allocation for quantized control over noisy channels
  • 2009
  • Ingår i: Final Proceedings of the 2009 7th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks. - 9781424449200 ; , s. 595-603
  • Konferensbidrag (refereegranskat)abstract
    • To achieve satisfactory overall performance, optimal rate allocation in a networked control system with highly limited communication resources is instrumental. In this paper, a rate allocation technique for state feedback control in linear dynamic systems over a noisy channel is proposed. The method consists of two steps: (i) the overall cost is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize the overall distortion is solved. It is shown that a non-uniform quantization is in general the best strategy for state feedback control over noisy channels. Monte Carlo simulations illustrate the proposed scheme, which is shown to have good performance when compared to arbitrarily selected rate allocations.
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21.
  • Bao, Lei, 1976- (författare)
  • Source-channel coding for closed-loop control
  • 2006
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Networked embedded control systems are present almost everywhere. A recent trend is to introduce wireless sensor networks in these systems, to take advantage of the added mobility and flexibility offered by wireless solutions. In such networks, the sensor observations are typically quantized and transmitted over noisy links. Concerning the problem of closed-loop control over such non-ideal communication channels, relatively few works have appeared so far. This thesis contributes to this field, by studying some fundamentally important problems in the design of joint source--channel coding and optimal control. The main part of the thesis is devoted to joint design of the coding and control for scalar linear plants, whose state feedbacks are transmitted over binary symmetric channels. The performance is measured by a finite-horizon linear quadratic cost function. The certainty equivalence property of the studied systems is utilized, since it simplifies the overall design by separating the estimation and the control problems. An iterative optimization algorithm for training the encoder--decoder pairs, taking channel errors into account in the quantizer design, is proposed. Monte Carlo simulations demonstrate promising improvements in performance compared to traditional approaches. Event-triggered control strategies are a promising solution to the problem of efficient utilization of communication resources. The basic idea is to let each control loop communicate only when necessary. Event-triggered and quantized control are combined for plants affected by rarely occurring disturbances. Numerical experiments show that it is possible to achieve good control performance with limited control actuation and sensor communication.
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23.
  • Cao, Lei, et al. (författare)
  • Cigarette smoke upregulates rat coronary artery endothelin receptors in vivo.
  • 2012
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Cigarette smoking is a strong cardiovascular risk factor and endothelin (ET) receptors are related to coronary artery diseases. The present study established an in vivo secondhand smoke (SHS) exposure model and investigated the hypothesis that cigarette smoke induces ET receptor upregulation in rat coronary arteries and its possible underlying mechanisms.
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24.
  • Cao, Lei, et al. (författare)
  • Secondhand cigarette smoke exposure causes upregulation of cerebrovascular 5-HT(1B) receptors via the Raf/ERK/MAPK pathway in rats.
  • 2013
  • Ingår i: Acta Physiologica. - : Wiley. - 1748-1716 .- 1748-1708. ; 207:1, s. 183-193
  • Tidskriftsartikel (refereegranskat)abstract
    • AIM: Cigarette smoke exposure increases the risk of stroke. Upregulation of 5-hydroxytryptamine 1B (5-HT(1B) ) receptors is associated with the pathogenesis of cerebral ischemia. The present study examined the hypothesis that the expression of 5-HT(1B) receptors is altered in brain vessels after secondhand smoke (SHS) exposure. METHODS: Rats were exposed to SHS in vivo for 200 min daily for 8 weeks. The contractile responses of isolated cerebral arteries were studies by a sensitive myograph. The mRNA and protein expression for 5-HT(1B) receptors were examined by real-time PCR, Western blot and immunofluorescence, respectively. In addition, the phosphorylation of Raf/extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinases (MAPK) pathway was evaluated. RESULTS: The results showed that SHS exposure shifted the 5-HT(1B) receptor-mediated concentration-contraction curve toward the left with a markedly increased maximum contraction. Furthermore, there were significant elevations in mRNA level and protein expression of 5-HT(1B) receptors in SHS-exposed rats. Immunostaining revealed that the 5-HT(1B) receptors were localized to the smooth muscle cells of cerebral arteries. SHS was also found to induce the phosphorylation of Raf-1 and ERK1/2 proteins. The administration of a Raf-1 inhibitor GW5074 attenuated the 5-HT(1B) receptor upregulation. CONCLUSION: SHS exposure upregulates cerebrovascular 5-HT(1B) receptors in rats. The receptor upregulation is associated with Raf/ERK/MAPK activation. © 2012 The Authors Acta Physiologica © 2012 Scandinavian Physiological Society.
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26.
  • Cao, Lei, et al. (författare)
  • Secondhand smoke exposure induces Raf/ERK/MAPK-mediated upregulation of cerebrovascular endothelin ETA receptors.
  • 2011
  • Ingår i: BMC Neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 12
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Cigarette smoking enhances the risk of stroke. However, the underlying molecular mechanisms are largely unknown. The present study established an in vivo rat secondhand cigarette smoking (SHS) model and examined the hypothesis that SHS upregulates endothelin receptors with increased cerebrovascular contraction via the Raf/extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinases (MAPK) pathway. RESULTS: Rats were exposed to SHS for up to 8 weeks. The cerebral artery vasoconstriction was recorded by a sensitive myograph. The mRNA and protein expressions for endothelin receptors in cerebral arteries were studied by real-time PCR and Western blot. Compared to fresh air exposed rats, cerebral arteries from SHS rats exhibited stronger contractile responses (P < 0.05) mediated by endothelin type A (ETA) receptors. The expressions of mRNA and protein for ETA receptors in the cerebral arteries from SHS rats were higher (P < 0.05) than that in control. SHS did not affect endothelin type B (ETB) receptor-mediated contractions, mRNA or protein levels. The results suggest that SHS upregulates ETA, but not ETB receptors in vivo. After SHS exposure, the mRNA levels of Raf-1 and ERK1/2, the protein expression of phosphorylated (p)-Raf-1 and p-ERK1/2 were increased (P < 0.05). Raf-1 inhibitor, GW5074 suppressed the enhanced ETA receptor-mediated contraction, mRNA and protein levels induced by SHS. In addition, GW5074 inhibited the SHS-caused increased mRNA and phosphorylated protein levels of Raf-1 and ERK1/2, suggesting that SHS induces activation of the Raf/ERK/MAPK pathway. CONCLUSIONS: SHS upregulates cerebrovascular ETA receptors via the Raf/ERK/MAPK pathway, which provides novel understanding of mechanisms involved in SHS-associated stroke.
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27.
  • Chen, Gan, et al. (författare)
  • Effects of Transition Metals on Metal–Octaaminophthalocyanine-Based 2D Metal–Organic Frameworks
  • 2023
  • Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 17:10, s. 9611-9621
  • Tidskriftsartikel (refereegranskat)abstract
    • Metal–octaaminophthalocyanine (MOAPc)-based 2D conductive metal–organic frameworks (cMOFs) have shown great potential in several applications, including sensing, energy storage, and electrocatalysis, due to their bimetallic characteristics. Here, we report a detailed metal substitution study on a family of isostructural cMOFs with Co2+, Ni2+, and Cu2+ as both the metal nodes and the metal centers in the MOAPc ligands. We observed that different metal nodes had variations in the reaction kinetics, particle sizes, and crystallinities. Importantly, the electronic structure and conductivity were found to be dependent on both types of metal sites in the 2D cMOFs. Ni-NiOAPc was found to be the most conductive one among the nine possible combinations with a conductivity of 54 ± 4.8 mS/cm. DFT calculations revealed that monolayer Ni-NiOAPc has neither the smallest bandgap nor the highest charge carrier mobility. Hence its highest conductivity stems from its high crystallinity. Collectively, these results provide structure property relationships for MOAPc-based cMOFs with amino coordination units. 
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28.
  • Chen, Hong, et al. (författare)
  • Construct Polyoxometalate Frameworks through Covalent Bonds
  • 2015
  • Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 54:17, s. 8699-8704
  • Tidskriftsartikel (refereegranskat)abstract
    • An emerging strategy for exploring the application of polyoxometalates (POMs) is to assemble POM clusters into open-framework materials, especially inorganic organic hybrid three-dimensional (3D) open-framework materials, via the introduction of different organic linkers between the POM clusters. This strategy has yielded a few 3D crystalline POMs of which a typical class is the group of polyoxometalate metal organic frameworks (POMMOFs). However, for reported POMMOFs, only coordination bonds are involved between the linkers and POM clusters, and it has not yet produced any covalently bonded polyoxometalate frameworks. Here, the concept of "covalently bonded POMs (CPOMs)" is developed. By using vanadoborates as an example, we showed that the 3D CPOMs can be obtained by a condensation reaction through the oxolation mechanism of polymer chemistry. In particular, suitable single crystals were harvested and characterized by single-crystal X-ray diffraction. This work forges a link among polymer science, POM chemistry, and open-framework materials by demonstrating that it is possible to use covalent bonds according to polymer chemistry principles to construct crystalline 3D open-framework POM materials.
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29.
  • Chen, Hongting, et al. (författare)
  • High-Efficiency Formamidinium Lead Bromide Perovskite Nanocrystal-Based Light-Emitting Diodes Fabricated via a Surface Defect Self-Passivation Strategy
  • 2020
  • Ingår i: Advanced Optical Materials. - : WILEY-V C H VERLAG GMBH. - 2162-7568 .- 2195-1071. ; 8:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Formamidinium lead bromide (FAPbBr(3)) nanocrystals (NCs) demonstrate great potential in light-emitting diode (LED) applications due to their pure green emission and excellent stability. However, the abundant defects at the surface of the NCs act as charge trapping centers and significantly increase the trap-assisted nonradiative recombination channels, hampering the performance improvement of LEDs based on FAPbBr(3) NCs. Herein, a facile self-passivation strategy of the surface defects is developed by introducing excess formamidinium bromide (FABr) during the colloidal synthesis of NCs, leading to much improved photoluminescence quantum yield (PLQY) of the obtained NCs. In addition, enhanced charge transport property is measured in the assembled films owing to the simultaneously declined insulating ligands at the surface of NCs. The molar ratio of FABr and PbBr2 is rationally optimized during the synthesis of NCs and high-efficient green-emissive LEDs are fabricated with a champion current efficiency of 76.8 cd A(-1), corresponding to an external quantum efficiency of 17.1%, which is among the best-performing green LEDs based on perovskite NCs so far.
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30.
  • Chen, Jingjing, 1982, et al. (författare)
  • 10 Gbps 16QAM transmission over a 70/80 GHz (E-band) radio test-bed
  • 2012
  • Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012. - : IEEE. - 9782874870286 - 9781467323024 - 9782874870262 ; , s. 556-559
  • Konferensbidrag (refereegranskat)abstract
    • A millimeter-wave radio test-bed is implemented which demonstrates 16QAM transmission over 70/80 GHz band for data rate up to 10 Gbps. Performance of the 16QAM transmitter and receiver is evaluated in a loop-back lab set-up. With the proposed 10 Gbps on single carrier system architecture, it is possible to achieve 40 Gbps over a 5 GHz bandwidth when combined with polarization and spatial multiplexing.
  •  
31.
  • Cheng, Shi-Ping, et al. (författare)
  • Haplotype-resolved genome assembly and allele-specific gene expression in cultivated ginger
  • 2021
  • Ingår i: Horticulture Research. - : Springer Nature. - 2052-7276. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Ginger (Zingiber officinale) is one of the most valued spice plants worldwide; it is prized for its culinary and folk medicinal applications and is therefore of high economic and cultural importance. Here, we present a haplotype-resolved, chromosome-scale assembly for diploid ginger anchored to 11 pseudochromosome pairs with a total length of 3.1 Gb. Remarkable structural variation was identified between haplotypes, and two inversions larger than 15 Mb on chromosome 4 may be associated with ginger infertility. We performed a comprehensive, spatiotemporal, genome-wide analysis of allelic expression patterns, revealing that most alleles are coordinately expressed. The alleles that exhibited the largest differences in expression showed closer proximity to transposable elements, greater coding sequence divergence, more relaxed selection pressure, and more transcription factor binding site differences. We also predicted the transcription factors potentially regulating 6-gingerol biosynthesis. Our allele-aware assembly provides a powerful platform for future functional genomics, molecular breeding, and genome editing in ginger.
  •  
32.
  • Christensen, Kirsten E., et al. (författare)
  • An open-framework silicogermanate with 26-ring channels built from seven-coordinated (Ge,Si)10(O, OH)28 clusters
  • 2008
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 130:12, s. 3758-3759
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a new open-framework silicogermanate SU-61 containing 26-ring channels with a low framework density. It can be seen as a crystalline analogue to the mesoporous silica MCM-41. The structure is built from the assembly of (Ge,Si)10(O,OH)28 clusters. It is the first time that silicon has been successfully introduced in the Ge10 cluster in significant amounts (21% of the tetrahedral sites). Five- and six-coordinated Ge10 clusters have previously been observed in other germanate compounds leading to either dense or open structures. In SU-61, the seven-coordinated clusters fall onto yet another underlying net, the osf net. SU-61, along with other Ge10 based frameworks, shows the versatility of the germanate system to adopt defined topologies playing on the connectivity of the clusters following the principles of net decoration and scale chemistry.
  •  
33.
  • Dam, Marie Inger, et al. (författare)
  • Sex pheromone biosynthesis in the sugarcane borer Diatraea saccharalis : paving the way for biotechnological production
  • Ingår i: Pest Management Science. - 1526-498X.
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The sugarcane borer Diatraea saccharalis (Lepidoptera) is a key pest on sugarcane and other grasses in the Americas. Biological control as well as insecticide treatments are used for pest management, but economic losses are still significant. The use of female sex pheromones for mating disruption or mass trapping in pest management could be established for this species, provided that economical production of pheromone is available. RESULTS: Combining in vivo labelling studies, differential expression analysis of transcriptome data and functional characterisation of insect genes in a yeast expression system, we reveal the biosynthetic pathway and identify the desaturase and reductase enzymes involved in the biosynthesis of the main pheromone component (9Z,11E)-hexadecadienal, and minor components hexadecanal, (9Z)-hexadecenal and (11Z)-hexadecenal. We next demonstrate heterologous production of the corresponding alcohols of the pheromone components, by expressing multiple steps of the biosynthetic pathway in yeast. CONCLUSION: Elucidation of the genetic basis of sex pheromone biosynthesis in D. saccharalis, and heterologous expression in yeast, paves the way for biotechnological production of the pheromone compounds needed for pheromone-based pest management of this species.
  •  
34.
  • Demski, Kamil, et al. (författare)
  • Manufacturing specialized wax esters in plants
  • 2022
  • Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 72, s. 391-402
  • Tidskriftsartikel (refereegranskat)abstract
    • Biologically produced wax esters can fulfil different industrial purposes. These functionalities almost drove the sperm whale to extinction from hunting. After the ban on hunting, there is a niche in the global market for biolubricants with properties similar to spermaceti. Wax esters can also serve as a mechanism for producing insect sex pheromone fatty alcohols. Pheromone-based mating disruption strategies are in high demand to replace the toxic pesticides in agriculture and manage insect plagues threatening our food and fiber reserves. In this study we set out to investigate the possibilities of in planta assembly of wax esters, for specific applications, through transient expression of various mix-and-match combinations of genes in Nicotiana benthamiana leaves. Our synthetic biology designs were outlined in order to pivot plant lipid metabolism into producing wax esters with targeted fatty acyl and fatty alcohols moieties. Through this approach we managed to obtain industrially important spermaceti-like wax esters enriched in medium-chain fatty acyl and/or fatty alcohol moieties of wax esters. Via employment of plant codon-optimized moth acyl-CoA desaturases we also managed to capture unusual, unsaturated fatty alcohol and fatty acyl moieties, structurally similar to moth pheromone compounds, in plant-accumulated wax esters. Comparison between outcomes of different experimental designs identified targets for stable transformation to accumulate specialized wax esters and helped us to recognize possible bottlenecks of such accumulation.
  •  
35.
  • Ding, Bao-Jian, et al. (författare)
  • A plant factory for moth pheromone production
  • 2014
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 1-3353
  • Tidskriftsartikel (refereegranskat)abstract
    • Moths depend on pheromone communication for mate finding and synthetic pheromones are used for monitoring or disruption of pheromone communication in pest insects. Here we produce moth sex pheromone, using Nicotiana benthamiana as a plant factory, by transient expression of up to four genes coding for consecutive biosynthetic steps. We specifically produce multicomponent sex pheromones for two species. The fatty alcohol fractions from the genetically modified plants are acetylated to mimic the respective sex pheromones of the small ermine moths Yponomeuta evonymella and Y. padella. These mixtures are very efficient and specific for trapping of male moths, matching the activity of conventionally produced pheromones. Our long-term vision is to design tailor-made production of any moth pheromone component in genetically modified plants. Such semisynthetic preparation of sex pheromones is a novel and cost-effective way of producing moderate to large quantities of pheromones with high purity and a minimum of hazardous waste.
  •  
36.
  • Ding, Bao Jian, et al. (författare)
  • Bioproduction of (Z,E)-9,12-tetradecadienyl acetate (ZETA), the major pheromone component of Plodia, Ephestia, and Spodoptera species in yeast
  • 2022
  • Ingår i: Pest Management Science. - : Wiley. - 1526-498X .- 1526-4998. ; 78:3, s. 1048-1059
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: (Z,E)-9,12-tetradecadienyl acetate (ZETA, Z9,E12-14:OAc) is a major sex pheromone component for many stored-product moth species. This pheromone is used worldwide for mating disruption, detection, monitoring, and mass trapping in raw and processed food storage facilities. In this study, we demonstrate the biological production of ZETA pheromone by engineered yeast Saccharomyces cerevisiae. RESULTS: We mined the pheromone gland transcriptome data of the almond moth, Ephestia (Cadra) cautella (Walker), to trace a novel E12 fatty acyl desaturase and expressed candidates heterologously in yeast and Sf9 systems. Furthermore, we demonstrated a tailor-made ZETA pheromone bioproduction in yeast through metabolic engineering using this E12 desaturase, in combination with three genes from various sources coding for a Z9 desaturase, a fatty acyl reductase, and an acetyltransferase, respectively. Electrophysiological assays (gas chromatography coupled to an electroantennographic detector) proved that the transgenic yeast-produced ZETA pheromone component elicits distinct antennal responses. CONCLUSION: The reconstructed biosynthetic pathway in yeast efficiently produces ZETA pheromone, leaves an undetectable level of biosynthetic intermediates, and paves the way for the economically competitive high-demand ZETA pheromone's bioproduction technology for high-value storage pest control.
  •  
37.
  • Ding, Bao Jian, et al. (författare)
  • Biosynthesis of the sex pheromone component (E,Z)-7,9-Dodecadienyl acetate in the European Grapevine Moth, Lobesia botrana, involving ∆11 desaturation and an elusive ∆7 desaturase
  • 2021
  • Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 47:3, s. 248-264
  • Tidskriftsartikel (refereegranskat)abstract
    • The European grapevine moth, Lobesia botrana, uses (E,Z)-7,9-dodecadienyl acetate as its major sex pheromone component. Through in vivo labeling experiments we demonstrated that the doubly unsaturated pheromone component is produced by ∆11 desaturation of tetradecanoic acid, followed by chain shortening of (Z)-11-tetradecenoic acid to (Z)-9-dodecenoic acid, and subsequently introduction of the second double bond by an unknown ∆7 desaturase, before final reduction and acetylation. By sequencing and analyzing the transcriptome of female pheromone glands of L. botrana, we obtained 41 candidate genes that may be involved in sex pheromone production, including the genes encoding 17 fatty acyl desaturases, 13 fatty acyl reductases, 1 fatty acid synthase, 3 acyl-CoA oxidases, 1 acetyl-CoA carboxylase, 4 fatty acid transport proteins and 2 acyl-CoA binding proteins. A functional assay of desaturase and acyl-CoA oxidase gene candidates in yeast and insect cell (Sf9) heterologous expression systems revealed that Lbo_PPTQ encodes a ∆11 desaturase producing (Z)-11-tetradecenoic acid from tetradecanoic acid. Further, Lbo_31670 and Lbo_49602 encode two acyl-CoA oxidases that may produce (Z)-9-dodecenoic acid by chain shortening (Z)-11-tetradecenoic acid. The gene encoding the enzyme introducing the E7 double bond into (Z)-9-dodecenoic acid remains elusive even though we assayed 17 candidate desaturases in the two heterologous systems.
  •  
38.
  • Ding, Bao-Jian, et al. (författare)
  • Terminal fatty-acyl-CoA desaturase involved in sex pheromone biosynthesis in the Winter Moth (Operophtera brumata)
  • 2011
  • Ingår i: Insect Biochemistry and Molecular Biology. - : Elsevier BV. - 1879-0240 .- 0965-1748. ; 41, s. 715-722
  • Tidskriftsartikel (refereegranskat)abstract
    • The Winter Moth (Operophtera brumata L., Lepidoptera: Geometridae) utilizes a single hydrocarbon, 1,Z3,Z6,Z9-nonadecatetraene, as its sex pheromone. We tested the hypothesis that a fatty acid precursor, Z11,Z14,Z17,19-nonadecanoic acid, is biosynthesized from α-linolenic acid, through chain elongation by one 2-carbon unit, and subsequent methyl-terminus desaturation. Our results show that labeled α-linolenic acid is indeed incorporated into the pheromone component in vivo. A fatty-acyl-CoA desaturase gene that we found to be expressed in the abdominal epidermal tissue, the presumed site of biosynthesis for type II pheromones, was characterized and expressed heterologously in a yeast system. The transgenic yeast expressing this insect derived gene could convert Z11,Z14,Z17-eicosatrienoic acid into Z11,Z14,Z17,19-eicosatetraenoic acid. These results provide evidence that a terminal desaturation step is involved in the winter moth pheromone biosynthesis, prior to the decarboxylation.
  •  
39.
  • Ding, Yan, et al. (författare)
  • Psychometric properties of the Chinese version of Sense of Coherence Scale in women with cervical cancer.
  • 2011
  • Ingår i: Psycho-Oncology. - : Wiley. - 1099-1611 .- 1057-9249.
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: The purpose of this study was to test the psychometric properties of a Chinese version of the Sense of Coherence Scale (C-SOC-13) in women with cervical cancer in Mainland China. METHODS: The C-SOC-13 and Health-related Quality of Life scale (Functional Assessment of Cancer Therapy-Cervix) were administered to 238 women with cervical cancer. Validity was assessed in terms of factor validity, predictive validity, divergent validity and stability, whereas reliability was evaluated using Cronbach's alpha coefficient. RESULTS: This study showed that in confirmatory factor analysis, the first-order interrelated three-factor model and second-order model were performed based on Antonovsky's theoretical structure of Sense of Coherence (SOC). Both models fitted the data satisfactorily when the largest modification index was released. The chi-square value/degrees of freedom was 2.120, the goodness-of-fit index was 0.919, the root mean square error of approximation was 0.069, and the comparative fit index was 0.911. The Pearson correlation coefficient between SOC and Functional Assessment of Cancer Therapy-Cervix was 0.611. Enter multiple regression with SOC as a dependent variable and medical and socio-economic variables as independent variables showed no statistically significant partial coefficient of any independent variable in regression equation except for age. The Cronbach's alpha coefficient for the scale was 0.824. CONCLUSION: The factor validity, predictive validity and divergent validity of C-SOC-13 were reasonable, as well as the internal consistency. In general, C-SOC-13 showed to be suitable as an SOC measurement for women with cervical cancer in Mainland China. However, SOC may have a different meaning to Chinese people because of the philosophy and culture that shape the context of their lives. Generalizing the findings to other populations requires further psychometric evaluation of C-SOC-13. Further longitudinal studies are also needed to explore the stability.
  •  
40.
  • Duong, Quang Trung, et al. (författare)
  • Performance analysis of cooperative spatial multiplexing networks with AF/DF relaying and linear receiver over Rayleigh fading channels
  • 2015
  • Ingår i: Wireless Communications & Mobile Computing. - : Elsevier. - 1530-8669 .- 1530-8677. ; 15:3, s. 500-509
  • Tidskriftsartikel (refereegranskat)abstract
    • Cooperative spatial multiplexing (CSM) system has played an important role in wireless networks by offering a substantial improvement in multiplexing gain compared with its cooperative diversity counterpart. However, there is a limited number of research works that consider the performance of CSM systems. As such, in this paper, we have derived exact performance of CSM with amplify-and-forward and decode-and-forward relays in terms of outage capacity and ergodic capacity. We have shown that CSM systems yield a unity diversity order regardless of the number of antennas at the destination and the number of relays in the networks, which is the direct result of diversity and multiplexing gain trade-off. Our analytical expressions are corroborated by Monte-Carlo simulations.
  •  
41.
  • Fang, Li Tai, et al. (författare)
  • Establishing community reference samples, data and call sets for benchmarking cancer mutation detection using whole-genome sequencing
  • 2021
  • Ingår i: Nature Biotechnology. - : Springer Nature. - 1087-0156 .- 1546-1696. ; 39:9, s. 1151-1160
  • Tidskriftsartikel (refereegranskat)abstract
    • Tumor-normal paired DNA samples from a breast cancer cell line and a matched lymphoblastoid cell line enable calibration of clinical sequencing pipelines and benchmarking 'tumor-only' or 'matched tumor-normal' analyses. The lack of samples for generating standardized DNA datasets for setting up a sequencing pipeline or benchmarking the performance of different algorithms limits the implementation and uptake of cancer genomics. Here, we describe reference call sets obtained from paired tumor-normal genomic DNA (gDNA) samples derived from a breast cancer cell line-which is highly heterogeneous, with an aneuploid genome, and enriched in somatic alterations-and a matched lymphoblastoid cell line. We partially validated both somatic mutations and germline variants in these call sets via whole-exome sequencing (WES) with different sequencing platforms and targeted sequencing with >2,000-fold coverage, spanning 82% of genomic regions with high confidence. Although the gDNA reference samples are not representative of primary cancer cells from a clinical sample, when setting up a sequencing pipeline, they not only minimize potential biases from technologies, assays and informatics but also provide a unique resource for benchmarking 'tumor-only' or 'matched tumor-normal' analyses.
  •  
42.
  • Feng, Dawei, et al. (författare)
  • Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance
  • 2018
  • Ingår i: Nature Energy. - : Springer Science and Business Media LLC. - 2058-7546. ; 3:1, s. 30-36
  • Tidskriftsartikel (refereegranskat)abstract
    • For miniaturized capacitive energy storage, volumetric and areal capacitances are more important metrics than gravimetric ones because of the constraints imposed by device volume and chip area. Typically used in commercial supercapacitors, porous carbons, although they provide a stable and reliable performance, lack volumetric performance because of their inherently low density and moderate capacitances. Here we report a high-performing electrode based on conductive hexaaminobenzene (HAB)-derived two-dimensional metal-organic frameworks (MOFs). In addition to possessing a high packing density and hierarchical porous structure, these MOFs also exhibit excellent chemical stability in both acidic and basic aqueous solutions, which is in sharp contrast to conventional MOFs. Submillimetre-thick pellets of HAB MOFs showed high volumetric capacitances up to 760 F cm(-3) and high areal capacitances over 20 F cm(-2). Furthermore, the HAB MOF electrodes exhibited highly reversible redox behaviours and good cycling stability with a capacitance retention of 90% after 12,000 cycles. These promising results demonstrate the potential of using redox-active conductive MOFs in energy-storage applications.
  •  
43.
  • He, Zhongxia Simon, 1984, et al. (författare)
  • A Hardware Efficient Implementation of a Digital Baseband Receiver for High-Capacity Millimeter-Wave Radios
  • 2015
  • Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 63:5, s. 1683-1692
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents an implementation solution for a digital baseband receiver, which consists mainly of an analog symbol timing recovery (STR) block and a digital carrier recovery block. The STR is realized based on "one-sample-per-symbol" sampling, resulting in relaxed requirement on the A/D converters sampling speed. In this sense, the proposed implementation solution is hardware efficient. To functionally verify the solution, a proof-of-concept E-band link system is implemented and tested in the laboratory, which supports 5-Gbit/s data traffic using 16 quadrature amplitude modulation. The test results demonstrate that the proposed solution works for high-capacity millimeter-wave radios for point-to-point links, one of the targeted applications.
  •  
44.
  • Holkenbrink, Carina, et al. (författare)
  • Production of moth sex pheromones for pest control by yeast fermentation
  • 2020
  • Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176. ; 62, s. 312-321
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of insect sex pheromones is an alternative technology for pest control in agriculture and forestry, which, in contrast to insecticides, does not have adverse effects on human health or environment and is efficient also against insecticide-resistant insect populations. Due to the high cost of chemically synthesized pheromones, mating disruption applications are currently primarily targeting higher value crops, such as fruits. Here we demonstrate a biotechnological method for the production of (Z)-hexadec-11-en-1-ol and (Z)-tetradec-9-en-1-ol, using engineered yeast cell factories. These unsaturated fatty alcohols are pheromone components or the immediate precursors of pheromone components of several economically important moth pests. Biosynthetic pathways towards several pheromones or their precursors were reconstructed in the oleaginous yeast Yarrowia lipolytica, which was further metabolically engineered for improved pheromone biosynthesis by decreasing fatty alcohol degradation and downregulating storage lipid accumulation. The sex pheromone of the cotton bollworm Helicoverpa armigera was produced by oxidation of fermented fatty alcohols into corresponding aldehydes. The resulting yeast-derived pheromone was just as efficient and specific for trapping of H. armigera male moths in cotton fields in Greece as a conventionally produced synthetic pheromone mixture. We further demonstrated the production of (Z)-tetradec-9-en-1-yl acetate, the main pheromone component of the fall armyworm Spodoptera frugiperda. Taken together our work describes a biotech platform for the production of commercially relevant titres of moth pheromones for pest control via yeast fermentation.
  •  
45.
  • Lei, XG, et al. (författare)
  • Paradoxical Roles of Antioxidant Enzymes: Basic Mechanisms and Health Implications
  • 2016
  • Ingår i: Physiological reviews. - : American Physiological Society. - 1522-1210 .- 0031-9333. ; 96:1, s. 307-364
  • Tidskriftsartikel (refereegranskat)abstract
    • Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from aerobic metabolism, as a result of accidental electron leakage as well as regulated enzymatic processes. Because ROS/RNS can induce oxidative injury and act in redox signaling, enzymes metabolizing them will inherently promote either health or disease, depending on the physiological context. It is thus misleading to consider conventionally called antioxidant enzymes to be largely, if not exclusively, health protective. Because such a notion is nonetheless common, we herein attempt to rationalize why this simplistic view should be avoided. First we give an updated summary of physiological phenotypes triggered in mouse models of overexpression or knockout of major antioxidant enzymes. Subsequently, we focus on a series of striking cases that demonstrate “paradoxical” outcomes, i.e., increased fitness upon deletion of antioxidant enzymes or disease triggered by their overexpression. We elaborate mechanisms by which these phenotypes are mediated via chemical, biological, and metabolic interactions of the antioxidant enzymes with their substrates, downstream events, and cellular context. Furthermore, we propose that novel treatments of antioxidant enzyme-related human diseases may be enabled by deliberate targeting of dual roles of the pertaining enzymes. We also discuss the potential of “antioxidant” nutrients and phytochemicals, via regulating the expression or function of antioxidant enzymes, in preventing, treating, or aggravating chronic diseases. We conclude that “paradoxical” roles of antioxidant enzymes in physiology, health, and disease derive from sophisticated molecular mechanisms of redox biology and metabolic homeostasis. Simply viewing antioxidant enzymes as always being beneficial is not only conceptually misleading but also clinically hazardous if such notions underpin medical treatment protocols based on modulation of redox pathways.
  •  
46.
  • Lei, Ying, et al. (författare)
  • Enhanced airway smooth muscle cell thromboxane receptor signaling via activation of JNK MAPK and extracellular calcium influx.
  • 2011
  • Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 650:2-3, s. 629-638
  • Tidskriftsartikel (refereegranskat)abstract
    • Thromboxane is a key inflammatory mediator and potent airway constrictor. It acts on thromboxane A(2) (TP) receptors and contributes to airway inflammation and airway hyperresponsiveness that is the characteristic feature of asthma. The present study was designed to study TP receptor signaling in airway smooth muscle cells by using an organ culture model and a set of selective pharmacological inhibitors for mitogen-activated protein kinase (MAPK) and calcium signal pathways. Western-blot, immunohistochemistry, myograph and a selective TP receptor agonist U46619 were used for examining TP receptor signal proteins and function. Organ culture of rat bronchial segments for up to 48h induces a time-dependently increased airway contractile response to U46619. This indicates that organ culture increases TP receptor signaling in the airway smooth muscle cells. The enhanced bronchial contraction was attenuated by the inhibition of c-Jun N-terminal kinase (JNK) MAPK activity, chelation of extracellular calcium and calcium channel blocker nifedipine, suggesting that JNK MAPK activity and elevated intracellular calcium level are required for the TP receptor signaling. In conclusion, airway smooth muscle cell TP receptor signaling occurs via JNK MAPK activity and the elevation of extracellular calcium influx, which may provide knowledge for understanding the signaling pathway responsible for the modulation of TP receptor mediated airway hyperresponsiveness to thromboxane.
  •  
47.
  • Lei, Ying, et al. (författare)
  • The Raf-1 inhibitor GW5074 and dexamethasone suppress sidestream smoke-induced airway hyperresponsiveness in mice
  • 2008
  • Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Sidestream smoke is closely associated with airway inflammation and hyperreactivity. The present study was designed to investigate if the Raf-1 inhibitor GW5074 and the anti-inflammatory drug dexamethasone suppress airway hyperreactivity in a mouse model of sidestream smoke exposure. Methods: Mice were repeatedly exposed to smoke from four cigarettes each day for four weeks. After the first week of the smoke exposure, the mice received either dexamethasone intraperitoneally every other day or GW5074 intraperitoneally every day for three weeks. The tone of the tracheal ring segments was recorded with a myograph system and concentration-response curves were obtained by cumulative administration of agonists. Histopathology was examined by light microscopy. Results: Four weeks of exposure to cigarette smoke significantly increased the mouse airway contractile response to carbachol, endothelin-1 and potassium. Intraperitoneal administration of GW5074 or dexamethasone significantly suppressed the enhanced airway contractile responses, while airway epithelium-dependent relaxation was not affected. In addition, the smoke-induced infiltration of inflammatory cells and mucous gland hypertrophy were attenuated by the administration of GW5074 or dexamethasone. Conclusion: Sidestream smoke induces airway contractile hyperresponsiveness. Inhibition of Raf-1 activity and airway inflammation suppresses smoking-associated airway hyperresponsiveness.
  •  
48.
  • Lei, Ying, et al. (författare)
  • Up-regulation of bradykinin receptors in rat bronchia via IkappaB kinase-mediated inflammatory signaling pathway.
  • 2010
  • Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 634:1-3, s. 149-161
  • Tidskriftsartikel (refereegranskat)abstract
    • IkappaB kinase (IKK)-mediated intracellular signaling mechanisms may be involved in airway hyperresponsiveness through up-regulation of bradykinin receptors. This study was designed to examine if organ culture of rat bronchial segments induces airway hyperresponsiveness to bradykinin and if inhibition of IKK can abrogate the airway hyperresponsiveness to bradykinin via suppressing the expression of bradykinin B(1) and B(2) receptors. Rat bronchi were isolated and cut into ring segments. The segments were then organ cultured in the presence or absence of IKK inhibitors, BMS-345541 or TPCA-1. des-Arg(9)-bradykinin (B(1) receptor agonist) - and bradykinin (B(2) receptor agonist) - induced contractions of the segments were monitored by a sensitive organ bath system. The expression of bradykinin B(1) and B(2) receptors, inflammatory mediators and phosphorylated IKK were studied by a real-time PCR and/or by immunohistochemistry using confocal microscopy. Organ culture of the bronchial segments induced a time-dependent up-regulation of bradykinin B(1) and B(2) receptors. The IKK inhibitors abolished the organ culture-induced up-regulation of bradykinin B(1) and B(2) receptor-mediated contractions in a concentration-dependent manner. This was paralleled with inhibition of IKK activity (phosphorylation), reduced mRNA and protein expressions of bradykinin B(1) and B(2) receptors and decreased mRNA expression of inflammatory mediators (interleukin-6, inducible nitric oxide synthase, cyclooxygenase 2 and matrix metalloproteinase 9). Our results show that organ culture induces IKK-mediated inflammatory changes in airways which subsequently results in airway hyperresponsiveness to bradykinin via the up-regulated bradykinin receptors. Thus, IKK inhibition might be a promising approach for treatment of airway inflammation and airway hyperresponsiveness that are often seen in asthmatic patients.
  •  
49.
  • Li, Danqin, et al. (författare)
  • Enhanced and Balanced Charge Transport Boosting Ternary Solar Cells Over 17% Efficiency
  • 2020
  • Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32:34
  • Tidskriftsartikel (refereegranskat)abstract
    • Ternary architecture is one of the most effective strategies to boost the power conversion efficiency (PCE) of organic solar cells (OSCs). Here, an OSC with a ternary architecture featuring a highly crystalline molecular donor DRTB-T-C4 as a third component to the host binary system consisting of a polymer donor PM6 and a nonfullerene acceptor Y6 is reported. The third component is used to achieve enhanced and balanced charge transport, contributing to an improved fill factor (FF) of 0.813 and yielding an impressive PCE of 17.13%. The heterojunctions are designed using so-called pinning energies to promote exciton separation and reduce recombination loss. In addition, the preferential location of DRTB-T-C4 at the interface between PM6 and Y6 plays an important role in optimizing the morphology of the active layer.
  •  
50.
  • Li, Jie, et al. (författare)
  • Heat stress alters G-protein coupled receptor-mediated function and endothelium-dependent relaxation in rat mesenteric artery
  • 2008
  • Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 588:2-3, s. 280-285
  • Tidskriftsartikel (refereegranskat)abstract
    • Heat stress has been demonstrated to have strong cardiovascular effects. However, the underlying mechanism-mediated cardiovascular effects are still not fully understood. The present study was designed to examine if heat stress alters vascular G-protein coupled receptor-mediated vasomotion and endothelium function in rat mesenteric artery. Rats were divided into two groups, heat stress rats and control. The G-protein coupled receptors of endothelin type B (ETB) receptor-, endothelin type A (ETA) receptor-, 5-hydroxytryptamine (5-HT) receptor-, calcitonin gene-related peptide (CGRP) receptor-, alpha-adrenoceptor-mediated vosoactivity and endothelium-dependent relaxation on rat mesenteric artery ring segments were monitored by a myograph system. The plasma level of CGRP was determined by radioimmunological assay. Compared with control arterial segments, the contractile response curves of sarafotoxin 6c, a selective ETB receptor agonist and 5-HT in the arterial segments from heat stress rats were shifted towards left. An increased maximum contraction (E-max) induced by sarafotoxin 6c, but not 5-HT, was seen in the arterial segments from heat stress rats. CGRP-incluced relaxation in endothelium-denuded arterial segments from heat stress rats was enhanced. The relaxation in endothelium-intact arterial segments induced by acetylcholine was significantly decreased in heat stress rats. In addition, the plasma concentration of CGRP was increased in heat stress rats. The endothelium-dependent relaxation was characterized and shown there was a decrease in nitric oxide and endothelium-derived hyperpolarising factor-mediated relaxation in the arterial segments from heat stress rats. In conclusion, heat stress induces an enhanced vascular endothelin ETB-, 5-HT-receptors-mediated contraction, an enhanced CGRP-receptor-induced relaxation and damage to endothelium-dependent relaxation.
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