Preparation and electrochemical performance of hollow activated carbon fiber self-supported electrode for supercapacitor

Hollow activated carbon fiber (HACF) with high specific surface area and high charge storage capability was prepared by pre-oxidation, carbonization and KOH-activation from polyacrylonitrile (PAN). HACF was used as self-supported working electrode directly without any binder and conductive agent. The effect of the activation time on specific surface area of HACF was studied intensively. The results show that the specific surface area of HACF increased with the increase of activation time from 0.5 h to 1.5 h, and then decreased with further increase of activation time. Highest specific surface area of 1873 m(2)g(-1) and micropore volume of 0.61 cm(3)g(-1) were obtained in HACF activated for 1.5 h. Electrochemical properties of HACF can be improved with increase of activation time, but excessive activation results in the decrease of specific surface area and increase of internal resistance of HACF. The self-supported electrode of HACF possesses a large specific capacitance of 323 F g(-1) at 0.05 A g(-1) and 216 F g(-1) at 1 A g(-1). Therefore, HACF can be a promising self-supported electrode for high performance supercapacitors

An analysis of the vibrating motion of an axially moving thin plate using the HHT method

Axially moving plates can be found in many industrial applications. Characteristics of the motion of thin moving plates are demonstrated in this paper using real-time signals and the Hilbert-Huang transform method. Ensemble empirical mode decomposition (EEMD) and calculation procedures are used to determine the instantaneous frequency, Hilbert spectrum and marginal spectrum of a moving plate. Some comparisons between different cases are discussed briefly. The motion is sensitive to the velocity, the initial tension of the conveyor strings and the weight of the plate. In addition, to express the motion (including the pitch and roll) of a moving plate quantitatively for field applications, a motion indicator is introduced. The signal processing method used is based on EEMD and time domain filtering. The indicator should be helpful for monitoring or adjusting the motions of axially moving plates

l-Peptide functionalized dual-responsive nanoparticles for controlled paclitaxel release and enhanced apoptosis in breast cancer cells

Nanoparticles and macromolecular carriers have been widely used to increase the efficacy of chemotherapeutics, largely through passive accumulation provided by their enhanced permeability and retention effect. However, the therapeutic efficacy of nanoscale anticancer drug delivery systems is severely truncated by their low tumor-targetability and inefficient drug release at the target site. Here, the design and development of novel l-peptide functionalized dual-responsive nanoparticles (l-CS-g-PNIPAM-PTX) for active targeting and effective treatment of GRP78-overexpressing human breast cancer in vitro and in vivo are reported. l-CS-g-PNIPAM-PTX NPs have a relative high drug loading (13.5%) and excellent encapsulation efficiency (74.3%) and an average diameter of 275 nm. The release of PTX is slow at pH 7.4 and 25 °C but greatly accelerated at pH 5.0 and 37 °C. MTT assays and confocal experiments showed that the l-CS-g-PNIPAM-PTX NPs possessed high targetability and antitumor activity toward GRP78 overexpressing MDA-MB-231 human breast cancer cells. As expected, l-CS-g-PNIPAM-PTX NPs could effectively treat mice bearing MDA-MB-231 human breast tumor xenografts with little side effects, resulting in complete inhibition of tumor growth and a high survival rate over an experimental period of 60 days. These results indicate that l-peptide-functionalized acid - and thermally activated - PTX prodrug NPs have a great potential for targeted chemotherapy in breast cancer.</p

Strategies for intelligent interaction management and usability of biometric systems

Fingerprint biometric systems are one of the most popular biometric systems in current use, which takes a standard measure of a person's fingerprint to compare against the measure from an original stored template, which they have pre-acquired and associated with the known personal identification claimed by the user. Generally, the fingerprint biometric system consists of three stages including a data acquisition stage, a feature extraction stage and a matching extraction. This study will explore some essential limitations of an automatic fingerprint biometric system relating to the effects of capturing poor quality fingerprint images in a fingerprint biometric system and will investigate the interrelationship between the quality of a fingerprint image and other primary components of a fingerprint biometric system, such as the feature extraction operation and the matching process. In order to improve the overall performance of an automatic fingerprint biometric system, the study will investigate some possible ways to overcome these limitations. With the purpose of acquisition of an acceptable quality of fingerprint images, three components/enhancements are added into the traditional fingerprint recognition system in our proposed system. These are a fingerprint image enhancement algorithm, a fingerprint image quality evaluation algorithm and a feedback unit, the purpose of which is to provide analytical information collected at the image capture stage to the system user. In this thesis, all relevant information will be introduced, and we will also show some experimental results obtained with the proposed algorithms, and comparative studies with other existed algorithms will also be presented

Asymmetric Diffusion Based Channel-Adaptive Secure Wireless Semantic Communications

Semantic communication has emerged as a new deep learning-based communication paradigm that drives the research of end-to-end data transmission in tasks like image classification, and image reconstruction. However, the security problem caused by semantic attacks has not been well explored, resulting in vulnerabilities within semantic communication systems exposed to potential semantic perturbations. In this paper, we propose a secure semantic communication system, DiffuSeC, which leverages the diffusion model and deep reinforcement learning (DRL) to address this issue. With the diffusing module in the sender end and the asymmetric denoising module in the receiver end, the DiffuSeC mitigates the perturbations added by semantic attacks, including data source attacks and channel attacks. To further improve the robustness under unstable channel conditions caused by semantic attacks, we developed a DRL-based channel-adaptive diffusion step selection scheme to achieve stable performance under fluctuating environments. A timestep synchronization scheme is designed for diffusion timestep coordination between the two ends. Simulation results demonstrate that the proposed DiffuSeC shows higher robust accuracy than previous works under a wide range of channel conditions, and can quickly adjust the model state according to signal-to-noise ratios (SNRs) in unstable environments

Quantum properties of fermionic fields in multi-event horizon spacetime

We investigate the properties of quantum entanglement and mutual information in the multi-event horizon Schwarzschild-de Sitter (SdS) spacetime for massless Dirac fields. We obtain the expression for the evolutions of the quantum state near the black hole event horizon (BEH) and cosmological event horizon (CEH) in the SdS spacetime. Under the Nariai limit, the physically accessible entanglement and mutual information are maximized, and the physically inaccessible correlations are zero. With the increase in temperature of either horizon, the physically accessible correlations experience degradation. Notably, the initial state remains entangled and can be utilized in entanglement-based quantum information processing tasks, which differs form the scalar field case. Furthermore, the degradation of physically accessible correlations is more pronounced for small-mass black holes. In contrast, the physically inaccessible correlations separated by the CEH monotonically increase with the radiation temperature, and such correlations are not decisively influenced by the effect of particle creation at the BEH. Moreover, a similar phenomenon is observed for the inaccessible correlations separated by the BEH. This result differs from the single event spacetime, in which the physically inaccessible entanglement is a monotonic function of the Hawking temperature.Comment: 14 pages, 7 figure