Search

What is known and objective Administration of corticosteroids to immune checkpoint inhibitors (ICI)-treated patients has raised concerns due to doubts about ICIs' efficacy under those conditions. Hence, we reviewed studies comparing overall and progression-free survival (OS and PFS) outcomes in patients with non-small-cell lung carcinoma (NSCLC) treated with ICI and either with or without corticosteroids for any reason. Methods We searched the PubMed Central, Cochrane library, EMBASE and MEDLINE databases from inception until February 2021 for relevant publications. We used the Newcastle-Ottawa scale to assess the quality of the identified studies. We used the published data to carry out a meta-analysis with a random-effects model and report pooled odds ratios (ORs) with 95% confidence intervals (CIs). Results We included data from 14 studies with 5461 participants in the meta-analysis. Most studies were retrospective in nature and of low quality, and most of them were conducted in the USA and in European countries. Nivolumab is the most common ICI used in the included studies followed by pembrolizumab. We found that patients using corticosteroids had reduced OSs (pooled HR, 1.82; 95% CI, 1.51-2.18) and PFSs (pooled HR, 1.69; 95% CI, 1.41-2.04) than the patients not using corticosteroids. We identified significant heterogeneity and publication bias for both the outcomes. However, the sensitivity analysis revealed that the estimates were robust to the individual study effects. What is new and conclusion Our findings suggest that corticosteroids significantly reduce the OS and PFS of patients with NSCLC under ICI therapy. Hence, clinicians and oncologists should consider this information when prescribing corticosteroids for this target population.

Direct conversion of syngas (CO/H2) into higher alcohols is highly desirable but remains challenging due to the low C2+OH selectivity. Herein, an effective strategy was developed through the combin...

A highly dispersed KNiMo catalyst on Zn-modified MgAl-mixed oxide as a support is prepared by a surfactant-assistance hydrothermal method. The introduction of Zn can decrease the concentration of s...

Whether TERT promoter mutation is related to more aggressive clinicopathologic features and worse outcomes in papillary thyroid carcinoma patients (PTCs) is still variable and controversial. Our intention was to investigate the risk or prognostic factors that may additionally predict the TERT promoter mutation doable of these lesions and new prevention techniques in PTCs. A total of 2,539 PTC patients with 11.50% TERT mutation have been analyzed using Revman 5.3 software in this study. The PubMed and Embase databases were systematically searched for works published until November 9, 2021. The following variables had been associated with an extended chance of TERT promoter mutation in PTC patients: age < 45 years ( MD = 10.93 , 95 % CI = 7.25 – 14.61 ); gender = male ( pooled OR = 1.63 , 95 % CI = 1.17 – 2.28 ); tumor size > 1 cm ( MD = 0.56 , 95 % CI = 0.34 – 0.77 ); lymph node metastasis ( pooled OR = 1.29 , 95 % CI = 0.93 – 1.79 ); vascular invasion ( pooled OR = 1.78 , 95 % CI = 0.83 – 3.84 ); extrathyroidal extension ( pooled OR = 2.00 , 95 % CI = 1.32 – 3.02 ); distant metastasis ( pooled OR = 1.46 , 95 % CI = 1.04 – 2.04 ); advanced TNM stage ( pooled OR = 3.19 , 95 % CI = 2.28 – 4.45 ). In addition, multifocality ( pooled OR = 0.67 , 95 % CI = 0.14 – 3.24 ) had no affiliation with TERT promoter mutation in PTC patients. Our finding showed that age < 45 years, male, tumor size > 1 cm , lymph node metastasis, vascular invasion, and superior/advanced TNM stage were dangerous elements for TERT promoter mutation of worse effect in PTCs while that multifocality was once negatively correlated. TERT promoter mutation is drastically associated with recurrence and PTC-related mortality.

The unique hollow nanostructures (Ni1-xFex-HP) were fabricated by the template-engaged pyrolysis from amorphous (bi)metal-organic-frameworks with tunable polyhedron-like morphology by various Fe content. Ni1-xFex-HP features as hollow polyhedron with mesoporous wall, consisting of dominant metal/alloy coupled with a small fraction of their oxides and few-layer N-graphene shell (FLNG). Thanks for the structural and compositional feature to strengthen the synergism of Ni, NiO and N-graphene on HER, as well as FeNi alloy, NiFe oxide, and N-graphene on OER, the optimal Ni-HP and Ni0.5Fe0.5-HP octahedron present good bifunctional properties for HER (overpotential of 215 mV to reach 10 mA cm−2, Tafel slope of 133 mV dec−1) and OER (overpotential of 280 mV to reach 10 mA cm−2, Tafel slope of 79 mV dec−1) on glass carbon electrode in 1.0 M alkaline solution. Moreover, the electrocatalytic performance can be further enhanced by directly coating on nickel foam (NF), where the overpotentials of Ni-HP/NF and Ni0.5Fe0.5-HP/NF is only 98 and 220 mV at current density of 10 mA cm−2 for HER and OER, respectively. The integrated asymmetrical two-electrode configuration (Ni0.5Fe0.5-HP/NF||Ni-HP/NF) displays low cell voltage of 1.57 V to reach 10 mA cm−2, accompanying with strong durability for overall alkaline water splitting. This work opens up an effectively time-saving strategy using aMOFs with well-defined structure instead of highly crystalline metal-organic frameworks (cMOFs) as precursor to design hollow and nanostructured hybrids for energy conversion.

The chemical-coupled three-dimensional (3D) γ-MnOOH with CoOOH particles (γ-MnOOH/CoOOH) was fabricated through a two-step strategy involving a hydrothermal and reduction–oxidation process. The str...

The acidity/alkalinity and structural properties of NiMgAl trimetallic oxides (MMOs) can be effectively modulated by the alkaline-etching process with various etching times, which are further used as a support to prepare KMoS-based catalysts through the cetyltrimethylammonium bromide-encapsulated Mo-precursor strategy. The enriched surface anion groups in alkaline-etched MMO affect the textural properties, metal-support interaction, and sulfidation degree of the as-synthesized KMoS-based catalysts. As a result, KMoS-based catalysts using alkaline-etched MMO as supports effectively enhance the reducibility and dispersion of Mo species, which exert a positive influence on higher alcohol synthesis (HAS) performance in CO hydrogenation. A proper balance between acidity/alkalinity and structural properties in K, Mo/MMO-x catalysts can significantly enhance the alcohol selectivity in HAS from 55 to 65% (carbon selectivity). The formation of C2+ alcohols can be boosted by adol condensation with optimal acidic/ba...

Electrochemical water splitting is a promising way for the sustainable production of hydrogen, but the efficiency of the overall water-splitting reaction largely depends on the oxygen evolution reaction (OER) because of its sluggish kinetics. Herein, a series of hierarchical ZnCo2 O4 /Co3 O4 /NC-CNT (NC-CNT=nitrogen-rich carbon nanotube) mesoporous dodecahedrons grafted to carbon nanotubes have been synthesized from ZnCo bimetallic zeolitic imidazolate frameworks (ZnCo-ZIFs) through sequential pyrolysis in nitrogen and mild oxidation in air. The simultaneous modulation of oxygen vacancies, composition, and hierarchical mesoporous architecture remarkably enhanced their electronic conduction and the amount and reactivity of accessible actives; thus boosting their intrinsic activity in the OER. The optimal ZnCo2 O4 /Co3 O4 /NC-CNT-700 sample exhibited a large current density of 50 mA cm-2 at a potential of 1.65 V, a small Tafel slope of 88.5 mV dec-1 , and superior stability in alkaline media. This work should provide a facile strategy for the rational design of advanced OER catalysts by simultaneous engineering of oxygen vacancies and composition.

Objectives The treatment for neuropathic pain is still a big challenge. Pulsed radiofrequency technique has been widely used to relieve neuropathic pain in recent years. The purpose of this study is to optimize the temperature for pulsed radiofrequency therapy. Design Animal, experimental study. Methods Seventy-five male SD rats were randomly divided into five groups: Sham operation group (Sham group), chronic constriction injury group (CCI group), PRF 42°C group (P42 group), PRF 50°C group (P50 group), and PRF 60°C group (P60 group). The hindpaw withdrawal threshold (HWT), paw thermal withdrawal latency (PTWL), sciatic nerve structure, and the concentration of spinal methionine enkephalin(M-ENK) were detected to identify which temperature is the best for PRF treatment. Results PRF at 42°C, 50°C and 60°C significantly alleviated the pain in CCI rats. The therapeutic effects of 50°C and 60°C were similar, and both were better than 42°C. In addition, PRF using 42°C, 50°C, and 60°C mediated nerve injury to sciatic nerve were grade 1, 1, and 2, respectively. The concentration of M-ENK in spinal cord increased accompanying with the increasing of the temperature of PRF. Conclusions PRF using 50°C could induce less damage while achieving better improvement of mechanical and thermal pain threshold than 42°C and 60°C in CCI rats, which may be achieved by promoting the expression of M-ENK in spinal cord.

Water electrolysis provides a promising way to achieve sustainable hydrogen production, which strongly depends on highly effective electrocatalysts for industrial application. Herein, Mo2C/MoO2 heteronanorods have been synthesized by means of a simple self-templated carbothermal reduction of polymolybdate-melamine precursor. Through manipulating the pyrolysis temperature, the optimal Mo2C/MoO2-650 heteronanorods show a low overpotential (168, 290, and 204 mV) to achieve current density of 10 mA cm–2 in 0.5 M H2SO4, 0.1 M PBS, and 1.0 KOH, respectively, which also presents a small Tafel slope (∼58 and 87 mV dec–1), high mass activity (115.4 and 33.8 A g–1 at η = 200 mA), and outstanding stability in 0.5 M H2SO4 and 1.0 KOH. The superior performance is mainly ascribed to the heterointerfaces between Mo2C and MoO2 promoting synergistic effects, quasi 1D nanostructures facilitating fast charge/mass transfer, and high electrochemical active surface area (ECSA) providing a large number of available sites. This ...

Improving the C2+ alcohols selectivity is highly desirable for higher alcohols synthesis in CO hydrogenation. Herein, an effective method was developed for Mo-based supported catalysts by the combination of tungsten-doping and surfactant-assisted hydrothermal strategy. The tungsten-doping enhanced the interaction between Ni and W/Mo metal species to form more of the Ni-MoW-S phase with tunable slab size and stacking layers, and thus promoted the chain growth of alcohol to form a greater amount of higher alcohols in CO hydrogenation. The optimal K,Ni–Mo0.75W0.25/MMO-S exhibited a dominant double-layer structure (∼39.0%) and highly synergetic effects between Ni and W/Mo species, resulting in the highest total alcohol selectivity (76.1%) and in higher alcohols selectivity. This work provides a new route for tuning the morphology of MoS2/WS2 and synergetic effects between Ni and W/Mo species in supported catalysts to improve the selectivity of higher alcohols.

Certified reference materials (CRMs) for water content are used to calibrate or validate Karl Fischer titrations for accuracy and consistency. Ampoules of CRMs with low water content are typically prepared by a continuous packaging method, and the water content may decrease or increase over time as the CRM is dispensed. In the present study, we measured the water activities of solutions of water in xylene with various water contents. We found the equilibrated humidity of the solution increased as the water content increased. An improved continuous packaging method using a pre-equilibrated bottle was employed to prepare the CRM of xylene for water content. The average water contents of the solutions dispensed into the ampoules are 73 mg/kg (relative standard deviation 1.6 %) and 221 mg/kg (relative standard deviation 0.4 %). There was no obvious shift in the water contents in ampoules of these CRMs over time. Analysis of variance indicated that the water contents of these two CRM candidates in ampoules were homogeneous, and the relative uncertainties in the water contents because of the inhomogeneity were 1.2 and 0.3 % for the low and high water contents, respectively. This simple method dispenses xylene under its equilibrated humidity condition, which reduces the exchange of water between the solution and headspace. This method will be useful for the preparation of CRMs for low water content.

Metal-organic frameworks (MOFs), as precursors for synthesizing new carbon materials, hold promise for applications in the oxygen reduction reaction (ORR) as efficient non-precious metal catalysts. Here, a facile template-assisted strategy was adopted to fabricate a core-shell structure derived from MIL-101(Fe) and polyaniline. MIL-101(Fe) nanoparticles obtained by microwave-assisted synthesis were combined with PAni in different ratios and carbonized at 900 °C under flowing N2. An optimized core-shell Fe3O4/Fe3N@graphite carbon structure was successfully prepared and exhibited attractive ORR activity, with a half-wave potential of 0.916 V vs. RHE and an electron transfer number of 4.0 at 0.4 V vs. RHE. Furthermore, the catalyst displayed excellent stability in an alkaline solution. The superior ORR performance of the catalyst is mainly attributed to its stable core-shell structure, large specific surface area and high content of electrocatalytically active N species.

Despite intense research in the past decades, the lack of high-performance catalysts for fuel cell reactions remains a challenge in realizing fuel cell applications. Herein, we report a novel hybrid nanomaterial of platinum-nickel hydroxide-nanotubes (Pt/Ni(OH)2/CNTs) for improving electrocatalytic performance in alkaline environments. Ni(OH)2 was directly grown on functionalized nanotubes and then, Pt nanoparticles were in situ immobilized by the microwave synthesis method. Due to electronic and synergistic effects, 10 : 2-Pt/Ni(OH)2/N-CNT catalyst exhibited 2.77 times specific activity and 6.27 times mass activity toward methanol oxidation reaction (MOR), which were higher than those of commercial Pt/C in alkaline solution. The CO-stripping experiments and hydrogen evolution reaction (HER) further demonstrated that Ni(OH)2 could promote oxidation removal of carbonaceous poison for MOR via accelerating water dissociation: (i) Ni(OH)2 acted on an H2O molecule, leading to the formation of OHad; (ii) OHad oxidized the intermediate COad to CO2. Furthermore, the 10 : 2-Pt/Ni(OH)2/N-CNT catalyst also exhibited 2.07 times specific activity and 1.67 times mass activity toward oxygen reduction reaction (ORR), which were higher than those of commercial Pt/C in alkaline solution and Pt/N-CNT catalysts. Thus, the preparation of this hybrid nanomaterial provides a new direction for catalyst performance optimization towards next-generation fuel cells in alkaline environments.

The temperature of thermogravimetric analyzer (TG) was commonly calibrated by the reference material of ferromagnetic for Curie point (T c). RM for T c was used to be determined by simultaneous thermal analyzer (STA). Three certified reference materials (CRMs) including Alumel, nickel and iron were developed. Prior to the certification, the effects of the heating rate, the magnetic field strength and the type of sample pan upon T c were investigated using STA and TG. These CRMs were certified by an optimized STA method in a collaborative study with eight laboratories involved. Subsequently, their certified values (expanded uncertainties) were 153.9 °C (1.1 °C), 358.7 °C (1.3 °C) and 771.4 °C (1.5 °C), respectively.

Microwave (MW)-assisted heating, due to its unique properties has been used for synthesis of metal, oxide, zeolite, and metal-organic framework (MOF), and even to carry out organic reactions. However, less attention has been paid to integration of two or more functional components into advanced materials by MW-assisted strategy. We report herein for the first time for controllable integration of silver nanoparticles (NPs) and IRMOF-3 as a core-shell Ag@IRMOF-3 nanostructures into highly efficient catalysts by a facile one-pot MW irradiation method. Impressively, the uniform core-shell Ag@IRMOF-3 nanostructures can be fabricated as short as 5 min and are highly active for three-component coupling reaction of amine, aldehyde and acetylene (A 3 -coupling) by MW-assisted heating strategy. Specifically, the Ag@IRMOF-3 with average size of Ag NPs of 5.2 nm and IRMOF-3 of 91.5 nm exhibited the highest turnover numbers and turnover frequencies of 3052 and 149,004 h −1 reported up to date, respectively, for the A 3 -coupling reaction. Thanks to the MOF shell coating, the Ag@IRMOF-3 can be recycled at least for 8 runs without losing any activity; furthermore, the size-selective catalysis was also successfully achieved due to the size selective for propargylamines with different sizes.

Despite the significant progress in the preparation of hollow structures, it is a challenge to build high-quality complex hollow structures with controllable morphology, particularly for multicomponent materials. Herein, a facile strategy was first developed to tune the morphology of coordinated transition bimetal complexes via controlling the growth rates of {111} and {100} facets using sulfur as a morphological modulator and template-engaged pyrolysis to form a unique hollow polyhedron (S–FeNi@NC). By virtue of the structural and compositional features, the optimized S–FeNi@NC hollow cuboctahedron shows excellent activities with a remarkably small overpotential of 272 mV to reach 20 mA cm−2, a lower Tafel slope with 84 mA dec−1, and an excellent durability without degradation after 5000 CV cycles toward oxygen evolution reaction (OER) in an alkaline medium. The strategy developed here provides a new path to prepare hollow transition metal hybrids with a tunable polyhedral structure for catalysis and energy conversion.

Mixed metal oxide (MMO)-supported MoS2 catalysts with tunable size and morphology of active phases for higher alcohol synthesis (HAS) were prepared by using encapsulated Mo-based precursors with cetyltrimethylammonium bromide (CTAB). The Ni–KMoS/MMO catalysts show enhanced activity and superior selectivity towards higher alcohols to those prepared by the multiple impregnation method and co-impregnation method. That is, the K,Ni–30Mo/MMO catalyst exhibits a high space time yield (STY) of 253 mg per g catalyst per h for C2+ alcohols, which is about 3.2 and 1.51 times higher than those of IM-K,Ni–30Mo/MMO and co-IM-K,Ni–30Mo/MMO. The compromise between the dispersion and stacking of supported MoS2 slabs via adjusting the metal–support interaction is crucial to providing abundant Mo edges for dispersing Ni species to achieve more accessible active sites. The remarkable increase in the number of highly dispersed and contacted NiSx and Ni–KMoSx dual active sites will provide highly effective synergism, and thus gives this catalyst enhanced activity and exceptional selectivity towards higher alcohols in CO hydrogenation.

Hydrogen produced from electrocatalytic water splitting is a promising route due to the sustainable powers derived from the solar and wind energy. However, the sluggish kinetics at the anode for water splitting makes the highly effective and inexpensive electrocatalysts desirable in oxygen evolution reaction (OER) by structure and composition modulations. Metal–organic frameworks (MOFs) have been intensively used as the templates/precursors to synthesize complex hollow structures for various energy-related applications. Herein, an effective and facile template-engaged strategy originated from bimetal MOFs is developed to construct hollow microcubes assembled by interconnected nanopolyhedron, consisting of intimately dominant FeNi alloys coupled with a small NiFe2O4 oxide, which was confined within carbonitride outer shell (denoted as FeNi/NiFe2O4@NC) via one-step annealing treatment. The optimized FeNi/NiFe2O4@NC exhibits excellent electrocatalytic performances toward OER in alkaline media, showing 10 mA·...

Metal-organic frameworks (MOFs), as precursors for synthesizing new carbon materials, hold promise for applications in the oxygen reduction reaction (ORR) as efficient non-precious metal catalysts. Here, a facile template-assisted strategy was adopted to fabricate a core-shell structure derived from MIL-101(Fe) and polyaniline. MIL-101(Fe) nanoparticles obtained by microwave-assisted synthesis were combined with PAni in different ratios and carbonized at 900 °C under flowing N2. An optimized core-shell Fe3O4/Fe3N@graphite carbon structure was successfully prepared and exhibited attractive ORR activity, with a half-wave potential of 0.916 V vs. RHE and an electron transfer number of 4.0 at 0.4 V vs. RHE. Furthermore, the catalyst displayed excellent stability in an alkaline solution. The superior ORR performance of the catalyst is mainly attributed to its stable core-shell structure, large specific surface area and high content of electrocatalytically active N species.

Replacement of precious platinum with efficient and low-cost catalysts for electrocatalytic hydrogen evolution reaction (HER) at low overpotentials holds tremendous promise for clean energy devices. Herein, molybdenum polysulfide (MoSx) anchored on a porous Zr-metal organic framework (Zr-MOF, UiO-66-NH2) by chemical interactions is fabricated by a facile and one-pot solvothermal method for HER application. The distinctive design of the Zr-MOF stabilized MoSx composite enables remarkable electrochemical HER activity with a Tafel slope of 59 mV·dec–1, a lower onset potential of nearly 125 mV, and a cathode current of 10 mA·cm–2 at an overpotential of 200 mV, which also exhibits excellent durability in an acid medium. The superior HER performance should ascribe to the fast electron transport from the less conducting MoSx nanosheets to the electrode, high effective surface area, and number of active sites, as well as the favorable delivery for local protons in the porous Zr-MOF structure during the electrocat...

Nanocrystals (NCs) with a multiply-twinned structure possess great potential in the field of electrocatalysis. Reduced graphene oxide (rGO) has been employed as a support to further improve the stability and activity of catalysts. However, the twinned structure is thermodynamically unstable due to the high total free energy, and it is difficult to control the shape of the crystals during preparation, especially when grown directly on the surface of rGO. Herein, multiply-twinned structural Au–Ag decahedra and icosahedra were grown directly in situ on rGO through a facile approach under microwave irradiation. Thanks to the synergy of abundant twin defects and the electronic effect of the intimate contact/interaction between the Au–Ag alloy and the rGO, these as-prepared Au–Ag NCs/rGO hybrids exhibit excellent activity and stability towards the hydrogen evolution reaction. In particular, Au–Ag icosahedra/rGO exhibits Pt-like electrocatalytic activity and enhanced stability compared to commercial Pt/C.

Electrochemical water splitting is a promising way for the sustainable production of hydrogen, but the efficiency of the overall water-splitting reaction largely depends on the oxygen evolution reaction (OER) because of its sluggish kinetics. Herein, a series of hierarchical ZnCo

Hydrogen produced from electrocatalytic water splitting is a promising route due to the sustainable powers derived from the solar and wind energy. However, the sluggish kinetics at the anode for water splitting makes the highly effective and inexpensive electrocatalysts desirable in oxygen evolution reaction (OER) by structure and composition modulations. Metal-organic frameworks (MOFs) have been intensively used as the templates/precursors to synthesize complex hollow structures for various energy-related applications. Herein, an effective and facile template-engaged strategy originated from bimetal MOFs is developed to construct hollow microcubes assembled by interconnected nanopolyhedron, consisting of intimately dominant FeNi alloys coupled with a small NiFe

The uncertainties in host signal modeling due to inherent model errors and various attack distortions have prompted the introduction of robust statistics theory in the context of watermark detection. Specifically, the epsi-contamination model was applied to describe the host signals, and statistically robust (SR) watermark detectors assuming known embedding strengths were derived. In this work, we investigate the robust detection structure for multiplicative watermarking. A detection-simulation (DS)-based approach to determine the contamination factor is also presented. Moreover, considering that the strengths of the watermark signals may be adapted to host signals and will very likely change after being distorted by attacks, we go further to propose the asymptotically robust detector for multiplicative watermarks, which can be viewed as the SR counterpart of the locally most powerful watermark detector in the same sense that the SR detector with full knowledge of the watermark strengths is the corresponding parallel for the optimum detector. Experiments on real images demonstrate the superiority of the new schemes over the conventional ones

Synthesizing noble metallic nanoparticles (NPs) enclosed by high-index facets (HIFs) is challenged as it involves the tuning of growth kinetics, the selective adsorption of certain chemical species, and the epitaxial growth from HIF enclosed seeds. Herein, a simple and general strategy is reported by using dual reduction agents and dual capping agents to prepare Pt-based alloy NPs with HIFs, in which both glycine and poly(vinylpyrrolidone) serve as the reductants and capping agents. Due to the facilely tunable growth/nucleation rates and protecting abilities of the reductants and capping agents, Pt concave nanocube (CNC), binary Pt-Ni CNC, ternary Pt-Mn-Cu CNC, and Pt-Mn-Cu ramiform polyhedron alloy NPs terminated by HIFs as well as other NPs with well-defined morphologies such as Pt-Mn-Cu nanocube and Pt-Mn-Cu nanoflower are obtained with this approach. Owing to the high density of low-coordinated Pt sites (HIF structure) and the unique electronic effect of Pt-Mn-Cu ternary alloys, the as-prepared Pt-Mn-Cu NPs show enhanced catalytic activity toward methanol and formic acid electro-oxidation reactions with excellent stability. This work provides a promising methodology for designing and fabricating Pt-based alloy NPs as efficient fuel cell catalyst.

Photoabsorption and photoresponse of Si Si 1−x Ge x quantum wells are studied by using 45° unpolarized light field. Besides the free carrier absorption, the absorption peaks corresponding to both intersubband and intervalence band transitions are observed. We find that the intervalance band transitions are Ge composition dependent, but the intersubband transitions are not sensitive to Ge composition.

This paper proposes a new pixel-wise perceptual mask based on a wavelet visible difference predictor (WVDP) for watermarking. The mask is very effective in that the embedding energy can be sufficiently exerted, and that the annoying global parameter controlling the watermark strength as in usual schemes can be dropped. The watermark sequence is drawn from a uniform distribution and added to all the detail bands after being masked. In the detection phase, a correlation detector is used, and the original image is not required. Experimental results show that our scheme provides very good performance both in terms of watermark unobtrusiveness and robustness.

The requirement of robustness is of fundamental importance for all watermarking schemes in various application scenarios. When talking about watermark robustness, we usually mean that the receiver performance degrades smoothly with the attack power. Here we look from another angle, i.e., robustness in statistics. A new detector structure which is robust to small uncertainties in host signal modeling for multiplicative watermarking in the discrete Fourier transform (DFT) domain is presented. By relying on robust statistics theory, an e-contamination model is applied to describe the magnitudes of the DFT spectrum, based on which we are able to derive a minimax detector that is most robust in a well-defined sense. Experiments on real images demonstrate that the new watermark detector performs more stably than classical ones.