Passive multimedia forensics has become an active topic in recent years. However, less attention has been paid to video forensics. Research on video forensics, and especially on automatic detection ...of object-based video forgery, is still in its infancy. In this paper, we develop an approach for automatic identification and forged segment localization of object-based forged video encoded with advanced frameworks. The proposed approach starts with a frame manipulation detector. An automatic algorithm is proposed to identify object-based video forgery based on the frame manipulation detector. Then, a two-stage automatic algorithm is provided to accurately locate the forged video segments in the suspicious video. To construct the proposed frame manipulation detector, motion residuals are generated from the target video frame sequence. We regard the object-based forgery in video frames as image tampering in the motion residuals and employ the feature extractors that are originally built for still image steganalysis to extract forensic features from the motion residuals. The experiments show that the proposed approach achieves excellent results in both forged video identification and automatic forged temporal segment localization.
Nickel-catalyzed C–H bond functionalization reactions provide an impressive alternative to those with noble metal catalysts due to their unique reactivity and low cost. However, the regioselective ...C(sp2)–H borylation reaction of arenes accomplished by nickel catalyst remains limited. We herein disclose a silyl-directed ortho C(sp2)–H borylation of substituted arenes with a Ni(cod)2/PMe3/KHMDS catalyst system. Using readily available starting materials, this protocol provides easy access to ortho-borylated benzylic hydrosilanes bearing flexible substitution patterns. These products can serve as versatile building blocks for the synthesis of sila or sila/borine heterocycles under mild conditions. Control experiments and DFT calculations suggest that a catalytic amount of base prompts the formation of Ni(II)-Bpin-ate complex, likely related to the C(sp2)–H bond activation. This borylation reaction might follow an unusual Ni(II)/Ni(IV) catalytic cycle.Nickel-catalyzed C–H bond functionalization reactions provide an impressive alternative to those with noble metal catalysts but the regioselective C(sp2)−H borylation reaction of arenes accomplished by nickel catalyst remains challenging. Here the authors disclose a silyl-directed ortho C(sp2)−H borylation of substituted arenes with a Ni(cod)2/PMe3/KHMDS catalyst system.
A scientific and rigorous study on the adsorption behavior and molecular mechanism of collector sodium oleate (NaOL) on a Ca2+-activated hydroxylated α-quartz surface was performed through ...experiments and density functional theory (DFT) simulations. The rarely reported hydroxylation behaviors of water molecules on the α-quartz (101) surface were first innovatively and systematically studied by DFT calculations. Both experimental and computational results consistently demonstrated that the adsorbed calcium species onto the hydroxylated structure can significantly enhance the adsorption of oleate ions, resulting in a higher quartz recovery. The calculated adsorption energies confirmed that the adsorbed hydrated Ca2+ in the form of Ca(H2O)3(OH)+ can greatly promote the adsorption of OL− on hydroxylated quartz (101). In addition, Mulliken population analysis together with electron density difference analysis intuitively illustrated the process of electron transfer and the Ca-bridge phenomenon between the hydroxylated surface and OL− ions. This work may offer new insights into the interaction mechanisms existing among oxidized minerals, aqueous medium, and flotation reagents.
Background
Bifurcation percutaneous coronary intervention (PCI) is a challenging procedure, but there are currently inadequate data about definite stent thrombosis (ST) rates of single‐stent versus ...double‐stent strategies (SS and DS, respectively).
Methods and results
Randomized clinical trials (RCTs) comparing SS and DS strategies were searched through PubMed, Embase, and the Cochrane Central Register of Controlled Trials. Fourteen RCTs involving 3,107 patients were analyzed. Owing to the high crossover rate (16.49%), both intention‐to‐treat (ITT) and as‐treated (AT) analyses were performed. In the ITT population, there was a significantly lower rate of early definite ST in the SS group (0.26%; DS group 1.14%; P = 0.021). Similarly, in the AT population, there was a significantly lower rate of early definite ST in the SS group (0.23%, DS group 1.07%; P = 0.042). True bifurcation subgroup analysis also showed a significantly lower early definite ST in the SS group (OR = 0.36, 95% CI = 0.15–0.86, P = 0.042) in the ITT population. There was no significant difference of overall, acute, subacute, and late definite ST between the 2 groups.
Conclusions
Early definite ST is reduced when a SS strategy is used in bifurcation lesions.
Sulfuration flotation is the most widely used technology in malachite beneficiation. However, the inhomogeneity of malachite surfaces usually results in a non-uniform sulfuration surface. The ...motivation of this work is attempt to adopt different functional combination collectors to enhance the sulfuration flotation of malachite. Accordingly, the flotation behaviors and adsorption mechanisms of benzohydroxamic acid (BHA) and sodium butyl-xanthate (SBX) on the surface of malachite were systematically investigated using flotation tests, zeta-potential measurements, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and first-principle calculations. The test results of vulcanization flotation showed that the combined collectors of SBX with BHA possessed a higher recovery than only using SBH by 20%, indicating that there may be a synergistic effect between BHA and SBX. The IR and Raman spectroscopy demonstrated that both BHA and SBX could chemically adsorb onto the malachite surface. The density functional theory (DFT) calculation results further indicated that the combined adsorption energy of BHA and SBX was much lower than that of only BHA or SBX, which confirmed the synergistic effects of BHA and SBX on the malachite surface. This work may shed new light on the design and development of more efficient combined flotation reagents.
Passive video forensics has become an active topic in recent years. Generally, a pristine video obtained from surveillance cameras or other video recording devices is single compressed. At the same ...time, double lossy compression will certainly be introduced in tampered videos since it needs to go through recompression to perform tampering on a commonly used compressed video. In the video's double compression, some traces are left due to the intrinsic effects of recompression. Traditional supervised learning is inefficient because it requires two classes (the pristine and the manipulated) that occur in the video to be exhaustively assigned labels. Actually, compared with pristine videos, manipulated videos with labels are more difficult to obtain. To address this problem, in this paper, one-class classification, which is often used for anomaly detection and only needs the target class, is introduced. We first treat all decompressed video frames as still images and extract subtractive pixel adjacency matrix (SPAM) steganalysis features to detect traces left in the double compression process. Then we adopt a Gaussian density-based one-class classifier since SPAM features extracted from pristine video frames approximately subject to the Gaussian distribution. Furthermore, we improve the robustness of the classifier by using ensemble strategy. Experimental results indicate that our proposed method exceeds other more complex one-class classification methods, and outperforms fully-supervised learning methods only by feeding features from single compressed video frames to our one-class classifier.
•L-cysteine could potentially become an efficient and low toxicity depressant in Cu-Mo separation;•The Cu-Mo flotation separation could be achieved by L-cysteine selective depressing ...chalcopyrite;•L-cysteine might adsorb on chalcopyrite to form a stable L-cysteine-Cu chelate compound.
In this work, L-cysteine was introduced as an environmentally-efficient flotation reagent in the selective separation of molybdenite from chalcopyrite. Its flotation performance and adsorption mechanism onto chalcopyrite were also investigated by flotation experiment, zeta potential, FTIR spectra, Raman spectra, TOF-SIMS measurements and DFT calculations. The flotation results indicated that L-cysteine exhibited stronger depressing ability than the conventional chalcopyrite depressants of Na2S, NaHS and sodium thioglycolate, suggesting it could become a promising potential depressant in the selective flotation separation of molybdenite from chalcopyrite. The results of zeta potential, FTIR spectra, TOF-SIMS and Raman spectra measurements demonstrated that L-cysteine might chemisorb on the Cu atoms of chalcopyrite surface via -SH and –NH2 groups to form a stable L-cysteine-Cu chelate compound. The DFT calculations further supported the experimental characterizations; the calculated adsorption reaction energy of L-cysteine with Cu in the (0 0 1) surface of chalcopyrite was much lower than that of L-cysteine with Fe, which implied that L-cysteine would prefer to adsorb onto the Cu site of chalcopyrite surface.
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•XPS and FT-IR measurements confirmed that water molecules could be chemically adsorbed on hematite surface.•The dissociative adsorption of water molecules on the hematite (104) ...surface is more advantageous.•A multilayer interface hydration model was proposed, including the hydroxyl hydration layer, the primary hydration layer, and the secondary hydration layer.
The interactions between water and oxide surfaces play an important role in many fields. In this work, the adsorption mechanism of water molecules on hematite (104) surface and the hydration microstructures were systematically investigated by means of FT-IR spectroscopy, X-ray photoelectron spectroscopy, and DFT calculations. The XPS measurements confirmed that water molecules can be chemically adsorbed on hematite surface, and the peak position of Fe3+ in the Fe 2p3/2 splitting peak is shifted to a high binding energy after hydration, which was confirmed by the computational results of partial density of state (PDOS) that the adsorption of water molecules can improve the energy of Fe 3d state in the surface approaching to that in the bulk. FT-IR analysis showed that the peak of OH bending vibration was almost disappeared and the intensity of the OH stretching vibration peak was significantly weakened after dehydration. The DFT calculations further indicated that about 30 water molecules can be well adsorbed on the hematite surface per unit nm2 area, resulting in hydroxyl hydration layer, the primary hydration layer, and the secondary hydration layer. This work sheds some new lights on the interface hydration of oxidized mineral.
A B(C6F5)3‐catalyzed hydroarylation of a series of 1,3‐dienes with various phenols has been established through a combination of theoretical and experimental investigations, affording structurally ...diverse ortho‐allyl phenols. DFT calculations show that the reaction proceeds through a borane‐promoted protonation/Friedel–Crafts pathway involving a π‐complex of a carbocation–anion contact ion pair. This protocol features simple and mild reaction conditions, broad functional‐group tolerance, and low catalyst loading. The obtained ortho‐allyl phenols could be further converted into flavan derivatives using B(C6F5)3 with good cis diastereoselectivity. Furthermore, this transformation was applied in the late‐stage modification of pharmaceutical compounds.
Just diene to be arylated: A strategy was developed for the chemoselective hydroarylation of 1,3‐dienes with phenols through a borane‐promoted protonation/Friedel–Crafts‐type mechanism (see scheme). The transformation showed good functional‐group compatibility for the efficient synthesis of diverse ortho‐allyl phenols.
A metal-free silyl-pyridylation of alkenes using silyl boronates and B2pin2 through a pyridine-mediated B-interelement activation has been demonstrated, which provides a practical strategy for a ...variety of C4-silylalkylated pyridines. DFT calculations and control experiments show that the reaction proceeds through a silyl radical addition/radical–radical coupling sequence. This protocol features a broad substrate scope and excellent functional group compatibility, and thus it showcases great potential in the late-stage modification of bioactive molecules.
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