In this report, a composite adsorbent in form of spherical beads generated from graphene oxide, chitosan, and magnetite (MGOCS) was developed and characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, and vibrating sample magnetometer. The adsorption ability of MGOCS towards reactive blue 19 (RB19) and Ni(II) ions, and the effect of various experimental factors including pH, adsorbent dosage, contact time, adsorbate concentration, temperature, and ionic strength were assessed in detail. The maximum adsorption capacities of MGOCS were 102.06?mg/g for RB19 and 80.48?mg/g for Ni(II). The adsorption process was thermodynamically favorable, spontaneous, exothermic, and best described by Langmuir (for Ni(II)) and Freundlich (for RB19) isotherms. The adsorption kinetics were well fitted with pseudo-first-order model for both adsorbates. The result indicated that the beads have feasibility as highly efficient and eco-friendly adsorbent to get rid of organic dyes and heavy metals from water due to their high adsorption capacity, easy recovery, and reusability. 相似文献
Full-duplex (FD) relay systems including a transmit antenna selection and a non-orthogonal multiple access (NOMA) methods are analyzed under presence of multiple eavesdroppers. A channel state information of both the considered system and eavesdroppers is assumed to be outdated and eavesdroppers eavesdrop information signals independently. A closed-form of secure outage probability (SOP), secrecy throughput of every user is derived to evaluate the secrecy performance, and the mathematical analysis approach is verified by the Monte-Carlo simulation. Furthermore, the Golden-Section Search algorithm is proposed to find the maximum of the secrecy throughput of the considered FD-NOMA system. Numerical results indicate that there exists the SOP floor in the considered system and it is constrained by the channel gain of near user. Moreover, there is the optimal signal to interference plus noise ratio value which minimizes the SOP of the system regardless of the number of eavesdroppers. In comparison with half-duplex NOMA model, the SOP of FD-NOMA model is better.
ABSTRACTWe previously developed Wrin’Tac, a tactile sensing system that can select sensing modalities by changing its morphology. In this paper, we present a computational model to estimate a wrinkle’s morphology and predict the output of embedded sensing elements in both static indentation and sliding action cases. We evaluated the wrinkle shape and the posture of the sensing element by calculating its height. The wrinkle’s mechanical change is assessed by ascertaining its stiffness under vertical indentation by a spherical indenter. The output voltages of the sensor under static indentation are calculated by the proposed model, and the experimental values have error less than 10%, which validates the accuracy of our proposed model. For dynamic sliding action, this proposed model clarified the capability of wrinkle morphology in an evaluation of such sliding action’s characteristics as the sliding direction and velocity. We also identified the role of the wrinkle’s morphology in the sensor’s sensitivity under different conditions of dynamic sliding motion, implying that this sensing system may select suitable sensitivity for specific sensation tasks. We expect this work to pave the way for assessing the role of morphological changes to tactile sensation and developing soft active tactile sensing systems. 相似文献
The kinetics of carburization of molybdenum by methane has been studied in a fluidized bed differential reactor. Scanning electron microphotographs of the reacting solids, at various conversion levels, have been analyzed. It has been shown that pore formation resulted in considerable increase in reaction rate. Initial rates are analyzed in terms of growth of superficial carbide nucleus. The rate of growth of the germs was found to decrease with time of reaction. A model is proposed to explain this decrease. 相似文献
In this study, graphene was added to LiFePO4 via a hydrothermal method to improve the lithium-ion-diffusion ability of LiFePO4. The influence of graphene addition on LiFePO4 was studied by X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, cycling test, and AC impedance analysis. The addition of graphene to LiFePO4 resulted in the formation of a LiFePO4–graphene composite; XRD observations revealed the composite to have a single phase with an olivine-type structure. Furthermore, LiFePO4 particles in the composite were stacked on the graphene sheet surface, thereby enabling the composite to form an effective conducting network and facilitate the penetration of the surface of active materials by an electrolyte. The lithium-ion-diffusion ability of the LiFePO4–graphene composite was greater than that of pure LiFePO4. Of a number of materials studied [namely, pure LiFePO4, LiFePO4–graphene (1 %), LiFePO4–graphene (5 %), and LiFePO4–graphene (8 %)], LiFePO4–graphene (5 %) delivered the best electrochemical performance with a lithium-ion-diffusion coefficient of 8.18 × 10?12 cm2 s?1 and the highest specific discharge capacity of 149 mAh g?1 at 0.17 C; in contrast, the corresponding values for pure LiFePO4 were 3.01 × 10?12 cm2 s?1 and 109 mAh g?1, respectively. Further, LiFePO4–graphene (5 %) showed a very high specific discharge capacity of 170 mAh g?1 at 0.1 C, which is equal to the theoretical capacity of LiFePO4. 相似文献
In this study, two distinct systems of biomaterials were fabricated and their potential use as a bilayer scaffold (BS) for
skin bioengineering applications was assessed. The initial biomaterial was a polycaprolactone/poly(lacto-co-glycolic acid)
(PCL/PLGA) membrane fabricated using the electrospinning method. The PCL/PLGA membrane M-12 (12% PCL/10% PLGA, 80:20) displayed
strong mechanical properties (stress/strain values of 3.01 ± 0.23 MPa/225.39 ± 7.63%) and good biocompatibility as demonstrated
by adhesion of keratinocyte cells on the surface and ability to support cell proliferation. The second biomaterial was a hydrogel
composed of 2% chitosan and 15% gelatin (50:50) crosslinked with 5% glutaraldehyde. The CG-3.5 hydrogel (with 3.5% glutaraldehyde
(v/v)) displayed a high porosity, ≥97%, good compressive strength (2.23 ± 0.25 MPa), ability to swell more than 500% of its
dry weight and was able to support fibroblast cell proliferation. A BS was fabricated by underlaying the membrane and hydrogel
casting method to combine these two materials. The physical properties and biocompatibility were preliminarily investigated
and the properties of the two biomaterials were shown to be complementary when combined. The upper layer membrane provided
mechanical support in the scaffold and reduced the degradation rate of the hydrogel layer. Cell viability was similar to that
in the hydrogel layer which suggests that addition of the membrane layer did not affect the biocompatibility. 相似文献
In this paper, we present a frame-patch matching based robust semi-blind video watermarking using KAZE feature. The KAZE feature is employed for matching the feature points of frame-patch with those of all frames in video for detecting the embedding and extracting regions. In our method, the watermark information is embedded in Discrete Cosine Transform (DCT) domain of randomly generated blocks in the matched region. In the extraction process, we synchronize the embedded region from the distorted video by using KAZE feature matching. Based on the matched KAZE feature points, RST (rotation, scaling, translation) parameters are estimated and the watermark information can be successfully extracted. Experimental results show that our proposed method is robust against geometrical attacks, video processing attacks, temporal attacks, and so on. 相似文献
Electro-ionic soft actuators, capable of continuous deformations replacing non-compliant rigid mechanical components, attract increasing interest in the field of next-generation metaverse interfaces and soft robotics. Here, a novel MXene (Ti3C2Tx) electrode anchoring manganese-based 1,3,5-benzenetricarboxylate metal-organic framework (MnBTC) for ultrastable electro-ionic artificial muscles is reported. By a facile supramolecular self-assembly, the Ti3C2Tx-MnBTC hybrid nanoarchitecture forms coordinate bond, hydrogen bond, and hydrophilic interaction with the conducting polymer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), resulting in a mechanically flexible and electro-ionically active electrode. The superior electrical and electrochemical performances of the electrode stem from the synergistic effects between intrinsically hierarchical nanoarchitecture of MnBTC and rapid electron transport behavior of Mxene, leading to fast diffusion and accommodation of ions in the ion-exchangeable membrane. The developed artificial muscle based on Ti3C2Tx-MnBTC is found to exhibit high bending displacement (12.5 mm) and ultrafast response time (0.77 s) under a low driving voltage (0.5 V), along with wide frequency response (0.1–10 Hz) and exceptional stability (98% retention at 43,200 s) without any distortion of actuation performance. Furthermore, the designed electro-active artificial muscle is successfully used to demonstrate mimicry of eye motions including eyelid blinking and eyeball movement in a doll. 相似文献