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131.
The purpose of this investigation was to evaluate the influence of percutaneous absorption of captopril from hydrophilic cellulose derivatives gel bases (carboxymethylcellulose sodium [CMC], hydroxypropylcellulose [HPC] and hydroxylpropylmethylcellulose [HPMC]. The effects of various types and concentrations of penetration enhancers on captopril percutaneous absorption from HPC gel through rabbit skin were evaluated and selected to obtain some optimal formulations for penetration study through human chest skin. Then the required flux (1488 microg/hr) for captopril transdermal drug delivery system to maintain the therapeutic minimum effective concentration through human skin was used to evaluate the development of the optimal formulations. The results indicated that the minimum administered areas for therapeutic minimum effective concentration of captopril (cap) gel containing decanol (dec) were 10.4 cm2 (5% cap, 7% dec) and 7.6 cm2 (7% cap, 7% dec). These areas were within acceptable range, so these formulations can possibly be developed for a transdermal drug delivery system.  相似文献   
132.
Colorless and organo-soluble polyimide (PI) films have been synthesized from an alicyclic dianhydride BCDA and aromatic diamine 3,4′-ODA in the cosolvent of DMAc and GBL via one-step process. The graphene oxide (GO) was mixed with the above PI in DMAc solution to fabricate the PI/GO nanocomposite films. With the addition of only 0.001 wt% of GO in PI matrix, the resultant nanocomposite (PI/GO-0.001) exhibits not only the enhanced resistance to moisture but also retains superior visible light transmission, enhanced mechanical strength, and excellent dimensional stability, simultaneously. The water-vapor-transmission-rate (WVTR) significantly reduced to 30 g mil m−2 day−1 for this nanocomposite compared to 181 g mil m−2 day−1 for pure PI. Notably, the PI/GO-0.001 nanocomposite also exhibits low coefficient of thermal expansion (CTE) of 41 ppm °C−1, which is benefited from the homogeneous distribution of ultrathin GO nanosheets in PI matrix.  相似文献   
133.
Chee Tsai  Ludwik Kurz 《Automatica》1983,19(3):279-288
The performance of a linear Kalman filter will degrade when the dynamic noise is not Gaussian. A robust Kalman filter based on the m-interval polynomial approximation (MIPA) method for unknown non-Gaussian noise is proposed. Two situations are considered: (a) the state is Gaussian and the observation noise is non-Gaussian; (b) the state is non-Gaussian and the observation noise is Gaussian. It is shown, as compared with other non-Gaussian filters, the MIPA Kalman filter is computationally feasible, unbiased, more efficient and robust. For the scalar model, Monte Carlo simulations are given to demonstrate the ideas involved.  相似文献   
134.
Electrochemical studies have been performed with the atmospheric corrosion monitor (ACM) under thin layers of electrolyte which were drying out at R.H. < 100%. Galvanic couples (Cu/steel, Cu/zinc) and one-metal (steel, zinc) ACMs were used. Measurements were carried out as a function of R.H. and Na2SO4 concentration. In addition, weight loss data were collected under identical conditions in thin layer experiments for steel and zinc in 0.01N solutions of NaCl, Na2SO4, HCl, H2SO4 and distilled H2O in air, air + 1 ppm SO2, argon and argon + 1 ppm SO2. The data obtained in air and air + SO2 were compared to weight loss results in bulk solutions.The electrochemical technique makes it possible to follow the changes of corrosion rates with time. As observed in outdoor exposure, a large increase of corrosion rates occurs when the electrolyte layers become very thin, shortly before the surface dries out. These findings explain the results of the weight loss data which show for most environments a much larger corrosion rate than in the bulk electrolyte. An accelerating effect of SO2 was observed for steel at higher R.H. values, while for zinc, no effect occurred in NaCl, Na2SO4 and H2SO4, but an inhibiting effect was measured in HCl and in distilled H2O.Since weight loss and electrochemical data were recorded under identical conditions, it is possible to determine how accurately the ACM data reflect the true corrosion rate. It was found for Cu/steel ACMs that the electrochemical data follow the same trends as the weight loss data, but account for only about 20% of the corrosion rate. Due to larger scatter in the weight loss data, a similar efficiency factor could not be determined for Cu/zinc. For steel and zinc ACMs, the true Tafel slopes are not known, which makes a calculation of corrosion rates doubtful. The low cell efficiency is considered to be due to local corrosion of single cell plates and to i.r.-drop effects.Despite the fact that exact corrosion rates cannot, at present, be obtained from ACM data, the technique appears very valuable for following the changes of atmospheric corrosion behaviour and for time-of-wetness measurements.  相似文献   
135.
In order to improve the capacity of the hidden secret data and to provide an imperceptible stego-image quality, a novel steganographic method based on least-significant-bit (LSB) replacement and pixel-value differencing (PVD) method is presented. First, a different value from two consecutive pixels by utilising the PVD method is obtained. A small difference value can be located on a smooth area and the large one is located on an edged area. In the smooth areas, the secret data is hidden into the cover image by LSB method while using the PVD method in the edged areas. Because the range width is variable, and the area in which the secret data is concealed by LSB or PVD method are hard to guess, the security level is the same as that of a single using the PVD method of the proposed method. From the experimental results, compared with the PVD method being used alone, the proposed method can hide a much larger information and maintains a good visual quality of stego-image.  相似文献   
136.
The nanomechanical characteristics of polycarbonate (PC) polymer were investigated by atomic force microscope (AFM) and nanoindentation. Scratching, wear properties, hardness and Young's modulus were obtained. The relationships between scribing feed and speed, surface depth and roughness and applied load were also investigated. The results indicated that as the applied load was increased, the furrow depth and the surface roughness increased. When the scribing feed was increased, the depth and roughness decreased. Increasing the furrow speed also decreased the surface roughness. The applied load is more significant than the scribing speed on the material removal rate. In addition, the Young's modulus and hardness of the polycarbonate material were 1.8 and 0.2 GPa, respectively.  相似文献   
137.
Metalenses have emerged as a new optical element or system in recent years, showing superior performance and abundant applications. However, the phase distribut...  相似文献   
138.
Architectures for packet switches are approaching the limit of electronic switching speed. This raises the question of how best to utilize advances in photonic technology to enable higher speeds. The authors introduce cascaded optical delay line (COD) architectures. The COD architectures utilize an extremely simple distributed electronic control algorithm to configure the states of 2×2 photonic switches and use optical fiber delay lines to temporarily buffer packets if necessary. The simplicity of the architectures may also make them suitable for “lightweight” all-electronic implementations. For optical implementations, the number of 2×2 photonic switches used is a significant factor determining cost. The authors present a “baseline” architecture for a 2×2 buffered packet switch that is work conserving and has the first-in, first-out (FIFO) property. If the arrival processes are independent and without memory, the maximum utilization factor is ρ, and the maximum acceptable packet loss probability is ϵ, then the required number of 2×2 photonic switches is O(log(ϵ)/log(γ)), where γ=ρ2/(ρ2+4-4ρ). If one modifies the baseline architecture by changing the delay line lengths then the system is no longer work conserving and loses the FIFO property, but the required number of 2×2 photonic switches is reduced to O(log[log(ϵ)/log(γ)]). The required number of 2×2 photonic switches is essentially insensitive to the distribution of packet arrivals, but long delay lines are required for bursty traffic  相似文献   
139.
This paper describes a high-performance indium phosphide (InP) monolithic microwave integrated circuit (MMIC) amplifier, which has been developed for application in radioastronomy and imaging-array receivers. Implemented using coplanar waveguide, the six-stage amplifier exhibits 15 db gain, 10 dB input and output return loss, and low noise figure over the 180-205 GHz frequency range. Only one design pass was needed to obtain excellent agreement between the predicted and measured characteristics of the circuit, a unique achievement in this frequency band. The circuit is also the first 180-205 GHz amplifier designed for and successfully fabricated using TRW's standard 0.1-μm InP HEMT process  相似文献   
140.
A graphene oxide (GO) film is functionalized with metal (Au) and metal‐oxide (MoOx) nanoparticles (NPs) as a hole‐extraction layer for high‐performance inverted planar‐heterojunction perovskite solar cells (PSCs). These NPs can increase the work function of GO, which is confirmed with X‐ray photoelectron spectra, Kelvin probe force microscopy, and ultraviolet photoelectron spectra measurements. The down‐shifts of work functions lead to a decreased level of potential energy and hence increased Voc of the PSC devices. Although the GO‐AuNP film shows rapid hole extraction and increased Voc, a Jsc improvement is not observed because of localization of the extracted holes inside the AuNP that leads to rapid charge recombination, which is confirmed with transient photoelectric measurements. The power conversion efficiency (PCE) of the GO‐AuNP device attains 14.6%, which is comparable with that of the GO‐based device (14.4%). In contrast, the rapid hole extraction from perovskite to the GO‐MoOx layer does not cause trapping of holes and delocalization of holes in the GO film accelerates rapid charge transfer to the indium tin oxide substrate; charge recombination in the perovskite/GO‐MoOx interface is hence significantly retarded. The GO‐MoOx device consequently shows significantly enhanced Voc and Jsc, for which its device performance attains PCE of 16.7% with great reproducibility and enduring stability.  相似文献   
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