184 research outputs found

    DWT-Based Data Hiding Technique for Videos Ownership Protection

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    This chapter proposes a wavelet data hiding scheme for video authentication and ownership protection. A watermark in the shape of a logo image will be hidden. In this research, a discrete wavelet transform (DWT) process is implemented using orthonormal filter banks, where the Y components of the YUV color space of the video frames are decomposed using DWT, and a watermark is inserted in one or more of the resulting sub-bands in a way that is fully controlled by the owner. Then, the watermarked video is reconstructed. The filters used for the DWT decompositions are randomly generated to increase the security of the algorithm. An enhanced detection technique is developed to increase the reliability of the system. The overall robustness of this scheme is measured when common attacks are applied to the test videos. Moreover, the proposed algorithm is used with the high-efficiency video coding (HEVC) technique to examine the whole performance. Furthermore, a selective denoising filter is built to eliminate the effect of the noise. The simulation results show that the proposed algorithm achieves well under both the visual and the metric tests. Moreover, it performed well against intentional and unintentional attacks. The average normalized correlation achieved is 97%, while the mean peak signal-to-noise ratio (PSNR) is 45 dB

    Nanostructures in Dye-Sensitized and Perovskite Solar Cells

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    Due to increase of attention in energy and environmental concerns, there has been much interest developed in clean and renewable energy technologies. The utilization of green and eco-friendly sunlight through solar cells like photovoltaic cells, photo-electrochemical cells, and dye-sensitize and perovskite solar cells (DSSCs and PSCs) produces energy demand. Due to high electron mobility, suitable band alignment, and high optical transparency, the binary and ternary transition metal oxide materials such as TiO2, SnO2, ZnO, WO3, Bi2O3 and SrTiO3, Zn2SnO4, BaSnO3, etc. have attracted considerable attention as DSSC and PSC electrode materials. Highly efficient solar cells with sustainable performance under severe mechanical deformations are in great demand in forming wearable power supply devices, essential for space technologies. In this regard, myriads of studies have progressed in developing the said metal oxides by various means of nanostructure forms. The aim of this chapter is to highlight research background, basic concepts, operating parameters, working principles, theoretical aspects, and selection of materials with essential properties for DSSCs and PSCs applications

    Utility of 2-cyano-N-(2-hydroxyethyl) acetamide in heterocyclic synthesis

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    This review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of 2-cyano-N-(2-hydroxyethyl) acetamide. The target compounds are important intermediates for the synthesis of a variety of synthetically useful and novel heterocyclic systems

    Population genetic data for 21 autosomal STR loci for the Saudi Arabian population using the GlobalFiler(®) PCR amplification kit

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    Highlights: * GlobalFiler® PCR amplification kit was used to generate a reference dataset for the population of Saudi Arabia. * SE33, D12S391, and D1S1656 in this kit are more informative for the population of Saudi Arabia than any locus in the AmpFlSTR® Identifiler® PCR amplification kit

    Regulating C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub> adsorption selectivity by electronic-state manipulation of iron in metal-organic frameworks

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    The separation of C2H2 from C2H2/CO2 mixture is of great importance, yet highly challenging in the petrochemical industry due to their similar physicochemical properties. While open-metal sites (OMSs) in metal-organic frameworks (MOFs) are known to possess high affinity toward C2H2, its selective adsorption performance regulated by the electronic state of the same OMSs remains unexplored. Here, we report a metal electronic-state manipulation approach to construct a pair of isostructural Fe-MOFs, namely LIFM-26(Fe[II]/Fe[III]) and LIFM-27(Fe[III]) with different Fe[II] or Fe[III] oxidation states on the Fe centers, which display mixed-valent Fe[II]/Fe[III] centers in the former and sole Fe[III] centers in the latter. Remarkably, LIFM-26(Fe[II]/Fe[III]) shows significantly enhanced C2H2 uptake capacity than LIFM-27(Fe[III]), attested by adsorption isotherms and IAST calculations, as well as simulated and experimental breakthrough experiments. Furthermore, in situ infrared (IR) and molecular calculations unveil that the presence of Fe[II] in LIFM-26(Fe[II]/Fe[III]) results in stronger Fe[II]–C2H2 interactions than Fe[III]–C2H2, which plays a key role in the C2H2/CO2 separation

    Solvent-free fabrication of broadband WS2 photodetectors on paper

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    Paper-based devices have attracted extensive attention due to the growing demand for disposable flexible electronics. Herein, we integrate semiconducting devices on cellulose paper substrate through a simple abrasion technique that yields high-performance photodetectors. A solvent-free WS2 film deposited on paper favors an effective electron-hole separation and hampers recombination. The as-prepared paper-based WS2 photodetectors exhibit a sensitive photoresponse over a wide spectral range spanning from ultraviolet (365 nm) to near-infrared (940 nm). Their responsivity value reaches up to ~270 mA W−1 at 35 V under a power density of 35 mW cm−2. A high performance photodetector was achieved by controlling the environmental exposure as the ambient oxygen molecules were found to decrease the photoresponse and stability of the WS2 photodetector. Furthermore, we have built a spectrometer using such a paper-based WS2 device as the photodetecting component to illustrate its potential application. The present work could promote the development of cost-effective disposable photodetection devices

    Low-cost and biodegradable thermoelectric devices based on van der Waals semiconductors on paper substrates

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    We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates. The devices are based on thin films of WS2, Te, and BP (P-type semiconductors) and TiS3 and TiS2 (N-type semiconductors), deposited by simply rubbing powder of these materials against paper. The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of (+1.32 ± 0.27) mV/K and (-0.82 ± 0.15) mV/K for WS2 and TiS3, respectively. Additionally, Peltier elements were fabricated by interconnecting the P-type and N-type films with graphite electrodes. A thermopower value up to 6.11 mV/K was obtained when the Peltier element is constructed with three junctions. The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic device

    Radially oriented mesoporous TiO2 microspheres with single-crystal–like anatase walls for high-efficiency optoelectronic devices

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    Highly crystalline mesoporous materials with oriented configurations are in demand for high-performance energy conversion devices. We report a simple evaporation-driven oriented assembly method to synthesize three-dimensional open mesoporous TiO2 microspheres with a diameter of ~800 nm, well-controlled radially oriented hexagonal mesochannels, and crystalline anatase walls. The mesoporous TiO2 spheres have a large accessible surface area (112 m2/g), a large pore volume (0.164 cm3/g), and highly single-crystal–like anatase walls with dominant (101) exposed facets, making them ideal for conducting mesoscopic photoanode films. Dye-sensitized solar cells (DSSCs) based on the mesoporous TiO2 microspheres and commercial dye N719 have a photoelectric conversion efficiency of up to 12.1%. This evaporation-driven approach can create opportunities for tailoring the orientation of inorganic building blocks in the assembly of various mesoporous materials.State Key Basic Research Program of China (2013CB934104 and 2012CB224805), the National Science Foundation (21210004), the Science and Technology Commission of Shanghai Municipality (08DZ2270500), the Shanghai Leading Academic Discipline Project (B108), King Abdulaziz City for Science and Technology (project no. 29-280), and Deanship of Scientific Research, King Saud University–The International Highly Cited Research Group Program (IHCRG#14-102). Y.L. also acknowledges the Interdisciplinary Outstanding Doctoral Research Funding of Fudan University (EZH2203302/001)
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