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81.
82.
Transdermal drug delivery (TDD) systems with feedback control have attracted extensive research and clinical interest owing to their unique advantages of convenience, self‐administration, and safety. Here, a self‐powered wearable iontophoretic TDD system that can be driven and regulated by the energy harvested from biomechanical motions is proposed for closed‐loop motion detection and therapy. A wearable triboelectric nanogenerator (TENG) is used as the motion sensor and energy harvester that can convert biomechanical motions into electricity for iontophoresis without stored‐energy power sources, while a hydrogel‐based soft patch with side‐by‐side electrodes is designed to enable noninvasive iontophoretic TDD. Proof‐of‐concept experiments on pig skin with dyes as model drugs successfully demonstrate the feasibility of the proposed system. This work not only extends the application of TENG in the biomedical field, but may also provide a cost‐effective solution for noninvasive, electrically assisted TDD with closed‐loop sensing and treatment.  相似文献   
83.
In this work, a nanohybrid material based on a freestanding polymeric liquid crystal network capable of postmodification via cation exchange to tune birefringence is proposed. The smectic liquid crystal films can be infiltrated with a variety of cations, thereby changing the refractive indices (ne and no) and the effective birefringence (Δn) of the nanohybrid material, with reversible cation infiltration occurring within minutes. Birefringence could be tuned between values of 0.06 and 0.19, depending on the cation infiltrated into the network. Upon infiltration, a decrease in the smectic layer spacing is found with layer contraction independent of the induced change in birefringence. Potential applications are in the field of specialty optical devices, such as flexible, retunable reflective filters.  相似文献   
84.
Changes in surface electromyographic (EMG) amplitude during sustained, fatiguing contractions are commonly attributed to variations in muscle fiber conduction velocity (MFCV), motor unit firing rates, transmembrane action potentials and the synchronization or recruitment of motor units. However, the relative contribution of each factor remains unclear. Analytical relationships relating changes in MFCV and mean motor unit firing rates to the root mean square (RMS) and average rectified (AR) value of the surface EMG signal are derived. The relationships are then confirmed using model simulation. The simulations and analysis illustrate the different behaviors of the surface EMG RMS and AR value with changing MFCV and firing rate, as the level of motor unit superposition varies. Levels of firing rate modulation and short-term synchronization that, combined with variations in MFCV, could cause changes in EMG amplitude similar to those observed during sustained isometric contraction of the brachioradialis at 80% of maximum voluntary contraction were estimated. While it is not possible to draw conclusions about changes in neural control without further information about the underlying motor unit activation patterns, the examples presented illustrate how a combined analytical and simulation approach may provide insight into the manner in which different factors affect EMG amplitude during sustained isometric contractions.  相似文献   
85.
对于绝大多数微控制器时钟电路而言,硅振荡器是一种简单且有效的解决方案。与晶体和陶瓷谐振器不同,基于硅材料的定时器具有抗振动、抗撞击和抗电磁干扰的优点。同时,硅振荡器不需要严格匹配的定时元件和线路板走线。  相似文献   
86.
Automatic quantification of changes in bone in serial MR images of joints   总被引:1,自引:0,他引:1  
Recent innovations in drug therapies have made it highly desirable to obtain sensitive biomarkers of disease progression that can be used to quantify the performance of candidate disease modifying drugs. In order to measure potential image-based biomarkers of disease progression in an experimental model of rheumatoid arthritis (RA), we present two different methods to automatically quantify changes in a bone in in-vivo serial magnetic resonance (MR) images from the model. Both methods are based on rigid and nonrigid image registration to perform the analysis. The first method uses segmentation propagation to delineate a bone from the serial MR images giving a global measure of temporal changes in bone volume. The second method uses rigid body registration to determine intensity change within a bone, and then maps these into a reference coordinate system using nonrigid registration. This gives a local measure of temporal changes in bone lesion volume. We detected significant temporal changes in local bone lesion volume in five out of eight identified candidate bone lesion regions, and significant difference in local bone lesion volume between male and female subjects in three out of eight candidate bone lesion regions. But the global bone volume was found to be fluctuating over time. Finally, we compare our findings with histology of the subjects and the manual segmentation of bone lesions.  相似文献   
87.
本文主介绍了电镀填孔技术,并探讨了DC和PPR电镀填孔技术的优缺点和影响填孔效果的相关因素。  相似文献   
88.
Performance of a system design for digital video broadcasting is examined with emphasis on mobile reception. Orthogonal frequency division multiplexing (OFDM) is used to achieve good bandwidth efficiency and to mitigate the intersymbol interference resulting from the channel delay spread. The resulting equivalent channel including OFDM can be modeled as a flat Rayleigh fading channel plus an interchannel interference (ICI) term due to the channel Doppler spread. This ICI term is analyzed and shown to result in an error floor. Performance improvements due to antenna diversity and trellis-coded modulation (TCM) are given. Finally, multiresolution modulation is discussed as a means of achieving graceful degradation and giving degrees of freedom for further performance improvement.This research was supported by the Multimedia Systems R & D Laboratory, Hitachi, Ltd.  相似文献   
89.
In a mobile ad hoc network (MANET), the nodes act both as traffic sources and as relays that forward packets from other nodes along multi-hop routes to the destination. Such networks are suited to situations in which a wireless infrastructure is unavailable, infeasible, or prohibitively expensive. However, the lack of a secure, trusted infrastructure in such networks make secure and reliable packet delivery very challenging. A given node acting as a relay may exhibit Byzantine behavior with respect to packet forwarding, i.e., arbitrary, deviant behavior, which disrupts packet transmission in the network. For example, a Byzantine node may arbitrarily choose to drop or misroute a certain percentage of the packets that are passed to it for forwarding to the next hop. In earlier work, we proposed a trust establishment framework, called Hermes, which enables a given node to determine the “trustworthiness” of other nodes with respect to reliable packet delivery by combining first-hand trust information obtained independently of other nodes and second-hand trust information obtained via recommendations from other nodes. A deficiency of the Hermes scheme is that a node can fail to detect certain types of Byzantine behavior, such as packet misforwarding directed at a particular source node. In this paper, we propose new mechanisms to make Hermes robust to Byzantine behavior and introduce a punishment policy that discourages selfish node behavior. We present simulation results that demonstrate the effectiveness of the proposed scheme in a variety of scenarios involving Byzantine nodes that are malicious both with respect to packet forwarding and trust propagation.  相似文献   
90.
Deliberate design of specific and sensitive molecular probes with distinctive physical/chemical properties for analyte sensing is of great significance. Herein, by taking advantage of the position‐dependent substituent effects, an aggregation‐induced emission featured iron (III) probe from ortho‐substituted pyridinyl‐functionalized tetraphenylethylene (TPE‐o‐Py) is synthesized. It displays high sensitivity and selectivity toward iron (III) detection. The recognition arises from the position isomer of ortho‐substitution, and the fact that TPE‐o‐Py has a low acid dissociation constant (pK a) that is close to that of hydrolyzed Fe3+. Importantly, TPE‐o‐Py as a light‐up fluorescence probe could be employed for Fe3+ sensing in living cells with a pronounced red‐shift in fluorescence emission.  相似文献   
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