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Traditional synthetic-aperture radar (SAR) imaging, while adept at capturing stationary scenes with clarity, often results in the blurring of moving targets due to Doppler spectrum disparities. To overcome this, this study introduces an innovative optical approach for imaging moving targets. By employing a spatial light modulator (SLM), the phase information of SAR data can be modulated onto a light beam. Then, the light propagation path is meticulously designed to take advantage of the free propagation of light to compensate for the phase differences in SAR data, thereby achieving focal clarity. Simulations and experimental validations have demonstrated that this method surpasses traditional digital imaging techniques in terms of focusing precision. Additionally, the processing delay is only as long as the time taken for light propagation. The optical path is simple, avoiding complex assembly and alignment. This novel approach opens up new possibilities for the SAR imaging of moving targets, offering potential applications in moving target extraction, separation, and velocity estimation. [ABSTRACT FROM AUTHOR]

Supported catalysts have attracted extensive attention due to their excellent catalytic performance and reliability in heterogeneous catalysis. In this work, we report a general synthesis strategy that achieves the self‐coupling reaction of acetylene derivatives to 1,3‐diyne efficiently under conditions of copper catalyst impregnated on the precursor formed by acetone and urea. The experiments were performed by screening the base, solvent, temperature, and so forth to determine the optimum reaction conditions and then characterization and analysis of the catalyst. The results demonstrate that the Cu/CuO@CN(8) exhibits extraordinary reactivity to the self‐coupling reaction and achieves a high turnover frequency (TOF = 96.8). Typically, the conversion of phenylacetylene reaches 99.9% under the optimal reaction conditions of NaOH (2 mmol) and tert‐butanol (2 ml) and O2 (1 atm) at 60°C for 1 h. Nevertheless, it is worth noting that Cu/CuO@CN(8) has a large specific surface area (626.07 m2 g−1) and low metal loading (3.3%) measured by Brunauer Emmett–Teller (BET) and ICP‐OES, respectively. Simultaneously, kinetics and mechanism are also discussed and analyzed, and the thermodynamic energy value is calculated as 22.74 kJ mol−1. Besides, the optimum catalyst can be reused five times under optimal conditions without a significant decrease in reactivity. [ABSTRACT FROM AUTHOR]

Methods of converting carbon dioxide into valuable chemicals are of great demand but their development is still challenging. Herein, we developed an efficient, green and facile synthetic method for the preparation of a Fe-cyanide complex. The target catalyst showed high catalytic activity for the cyclic reaction of carbon dioxide and epoxide under solvent free conditions and ambient pressure. Meanwhile, the effects of morphology of different catalysts on their catalytic activities were also investigated by the kinetic and thermodynamic studies. In addition, the catalyst could be recycled and reused for at least five successive cycles without significant decrease in the catalytic activity. This target catalyst thus represents one of the efficient and recyclable systems reported for the cyclic reaction in industry. [ABSTRACT FROM AUTHOR]

We study the asymptotic behavior of solutions to the constrained MFG system as the time horizon T goes to infinity. For this purpose, we analyze first Hamilton–Jacobi equations with state constraints from the viewpoint of weak KAM theory, constructing a Mather measure for the associated variational problem. Using these results, we show that a solution to the constrained ergodic mean field games system exists and the ergodic constant is unique. Finally, we prove that any solution of the first-order constrained MFG problem on [0, T] converges to the solution of the ergodic system as T goes to infinity. [ABSTRACT FROM AUTHOR]

• High surface area of the carbon materials were synthesized. • A phosphorus and nitrogen doped palladium nanomaterials support on carbon materials are prepared. • The catalyst used to selectivity hydrogenation of the phenylacetylene to styrene under mild conditions. • P element can change the electron density of Pd to increase the selectivity of reaction. In this work, two types of polyporous and coral-like materials (CN) with high specific surface area are prepared using sodium glutamate as a carrier. At the same time, a CN-supported phosphorus-nitrogen-doped palladium nanomaterial CN-P-Pd is synthesized and applied to the preparation of styrene by selective hydrogenation of phenylacetylene under mild conditions. As shown in the TEM images, Pd nanoparticles with a particle size of about 4.4 nm are uniformly dispersed on the surface of the carrier. The results of N 2 adsorption–desorption reveal that the surface area of the prepared catalyst (CN-P-Pd) is 1307 m2g−1. In addition, the experimental exploration shows the intervention of P in carbon-nitrogen materials can contribute to improve the selectivity of the reaction, which can be attributed to the fact that P element can change the electron density of Pd. Meanwhile, it is found that the solvent not only affects the activity of catalyst, but also the selectivity of the reaction. Kinetic study shows the activation energy of the reaction is 4.5 kJ/mol. With the increase of the reaction temperature, the dissolution rate of hydrogen in the solvent gradually slows down, which inhibits the progress of the reduction reaction. Mechanistic studies demonstrate that the carbon-nitrogen materials have strong adsorption capacity for substrates, and also provide more adsorption sites for phenylacetylene. Additionally, the optimal catalyst (CN-P-Pd) also has high reaction activity to other alkynes and the conversion can reach at 95%. Moreover, the optimal catalyst can be reused several times without significant reduction in reaction activity. [ABSTRACT FROM AUTHOR]

Rationally designing a high-efficiency, inexpensive and stable electrocatalyst is important in the renewable energy field. Herein, a one-step strategy is adopted to synthesize 3D hybrid of CoSe nanoparticles encapsulated nitrogen-doped carbon nanotubes graft onto nitrogen-doped carbon nanosheets (denoted as CoSe@NCNT/NCN) with excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in acidic and alkaline solutions, respectively. Benefiting from the unique morphology, the large surface area and good conductivity, the hybrid exhibits excellent electrocatalytic HER activity in 0.5 M H 2 SO 4 solution, which is a low overpotential of 197 mV at a current density of 10 mA cm−2 with a Tafel slope of 43 mV dec−1. Meanwhile, it presents a low overpotential of 301 mV at a current density of 10 mA cm−2 with a Tafel slope of 75 mV dec−1 in 1 M KOH solution for OER. The good electrocatalytic property is comparable to most of the previously reported Co-based electrocatalysts and the synthetic method is low toxic and simple, which may be expanded to other transition metal dichalcogenides. The strategy provides a possibility for preparation for effective nonprecious high performance HER and/or OER electrocatalysts. [ABSTRACT FROM AUTHOR]

We develop an elementary method to give a Lipschitz estimate for the minimizers in the problem of Herglotz' variational principle proposed in the paper (P. Cannarsa, W. Cheng, K. Wang, J. Yan, 2019 [17]) in the time-dependent case. We deduce Erdmann's condition and the Euler-Lagrange equation separately under different sets of assumptions, by using a generalized du Bois-Reymond lemma. As an application, we obtain a representation formula for the viscosity solution of the Cauchy problem for the Hamilton-Jacobi equation D t u (t , x) + H (t , x , D x u (t , x) , u (t , x)) = 0 and study the related Lax-Oleinik evolution. [ABSTRACT FROM AUTHOR]

A bifunctional electrocatalyst with peculiarly hierarchical snowflake-like iron doped CoP heterostructures self-assembled on copper foam was synthesised through a facile two-step pathway and employed for efficient OER, HER and overall water splitting. A bifunctional electrocatalyst with peculiarly hierarchical snowflake-like iron-doped CoP heterostructures self-assembled on copper foam (CoFeP/CF) was synthesized via a facile hydrothermal-phosphidation pathway. The excellent electrochemical performance of CoFeP/CF can be attributed to the synergistic effect of cobalt and iron atoms, tuneful interaction between metal atoms and phosphorus, and the large electrochemical active surface area origined from its peculiarly hierarchical snowflake-like heterostructures with high surface roughness. With the small Tafel slope values (of 73.0 mV dec−1 for OER and 90.4 mV dec−1 for HER), CoFeP/CF demands the diminutive overpotentials (of 277.9 mV for OER and 152.6 mV for HER) to desire the current density of 50 mA cm−2 in alkaline electrolyte. Furthermore, CoFeP/CF exhibits outstanding electrochemical performance for the overall water splitting with the cell potential of 1.495 V to attain 10 mA cm−2 in a two-electrode cell. [ABSTRACT FROM AUTHOR]

Exploration of noble-metal-free, highly-efficient and durable catalysts for Hydrogen evolution reaction (HER) remains a challenge. In this work, the development of carbon-coated cobalt-molybdenum-phosphide nanosheets supported on carbon cloth (Co-Mo-P@C) is successfully demonstrated. To obtain a better electrocatalystic performance, the different amount of glucose was added into the reaction system during hydrothermal process. Benefiting from the 2D structure, high electrical conductivity and sufficient active sites, the Co-Mo-P@C contained 0.5 mmol glucose exhibits relatively good catalytic activity for HER with low over poentials at −96 mV and −162 mV @ 10 mA cm−2 in acidic and alkaline medias respectively and the Tafel slope of 52.9 mV dec−1 and 34.3 mV dec−1. Additionally, the catalyst also shows good durability in the both electrolytes. • Co-M-P@C nanosheets supported on carbon cloth was prepared. • Relevantly good elecocatalytic performance for HER. • Influence of glucose content was investigated. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogen evolution reaction (HER) from water splitting is a promising way to promote the utilization of renewable energy. Designing and fabricating electrocatalysts with low cost, high catalytic activity and robust stability is desirable. In response, we prepared carbon shells encapsulating ultrafine β-Mo 2 C nanoparticles with N and P dual-doping as advanced electrocatalyst used for HER in both acidic and alkaline mediums. This paper gives a discussion on element doping and porosity which have influence on the HER performance. As introducing heteroatoms into carbon matrix to create active sites and enhance electron transfer capacity, the as-prepared electrocatalyst exhibits high catalytic activity with low overpotential of 117 mV and 121 mV to achieve current density of 10 mA cm−2 in acidic and alkaline solutions. Due to the strategy of carbon shells encapsulating, the catalyst presents robust stability for a long time at various applied potential. Furthermore, the design idea of using multiple strategies preparing catalysts may serve some inspiration to fabricate advanced electrocatalysts. [ABSTRACT FROM AUTHOR]

Improved resolutions of synthetic aperture radar (SAR) have complicated real-time high-accuracy imaging. To reduce the time and power required by digital processing algorithms, we propose a novel idea of photoelectric combination and design a SAR optical imaging system. Range matched filtering is realized in the digital domain, whereas azimuth autofocusing is realized through free propagation in the optical domain, with range cell migration correction at the speed of light. To adapt to changeable SAR parameters, a compound lens is formed by combining spatial light modulators. The system is simple, compact, efficient, and adaptable, with nano-second processing delays. [ABSTRACT FROM AUTHOR]

We present an innovative process for directly transforming poly(ethylene terephthalate) (PET), a polymer extensively used in food and beverage packaging, into trans-isomer-enriched 1,4-cyclohexanedimethanol (CHDM), a key ingredient in advanced specialty polymers. Our approach leverages a dual-catalyst system featuring palladium on reduced graphene oxide (Pd/r-GO) and oxalate-gel-derived copper-zinc oxide (og-CuZn), utilizing hydrogenation/hydrogenolysis relay catalysis. This method efficiently transforms PET into polyethylene-1,4-cyclohexanedicarboxylate (PECHD), which is then converted into CHDM with an impressive overall yield of 95 % in a two-stage process. Our process effectively handles various post-consumer PET plastics, converting them into CHDM with yields between 78 % and 89 % across different substrates. Additionally, we demonstrate the applicability and scalability of this approach through a temperature-programmed three-stage relay process on a 10-gram scale, which results in purified CHDM with an isolated yield of 87 % and a notably higher trans/cis ratio of up to 4.09/1, far exceeding that of commercially available CHDM. This research not only provides a viable route for repurposing PET waste but also enhances the control of selectivity patterns in multistage relay catalysis., (© 2024 Wiley-VCH GmbH.)

Nucleic acid detection plays a crucial role in various aspects of health care, necessitating accessible and reliable quantification methods, especially in resource-limited settings. This work presents a simplified electrochemical approach for end-point yet quantitative nucleic acid detection. By elevating the concentration of redox species and choosing potential as the signals, we achieved enhanced signal robustness, even in the presence of interfering substances. Leveraging this robustness, we accurately measured pH-induced redox potential changes in methylene blue solution for end-point nucleic acid detection after loop-mediated isothermal amplification (LAMP). Our method demonstrated quantitative detection of the SARS-CoV-2 N gene and human ATCB gene and successful discrimination of the human BRAF V600E mutation, comparable in sensitivity to commercial kits. The developed user-friendly electrochemical method offers a simplified and reliable approach for end-point yet quantitative detection of nucleic acids, potentially expanding the benefits of nucleic acid testing in resource-limited settings.

Here we present a hybrid catalytic pathway for efficient synthesis of 5-aminomethyl-2-furancarboxylic acid (AMFC), a bio-based nylon-6 analogue monomer, from 5-hydroxymethylfurfural (HMF). This method combines homogeneous-catalyzed selective oxidation of HMF to 5-formyl-2-furancarboxylic acid (FFCA) with heterogeneous-catalyzed reductive amination using ammonia as the nitrogen source. Through this relay strategy, we achieve significant enhancements in overall efficiency, resulting in isolation yields of up to 92% for highly selective and scalable AMFC production from HMF.

The electrooxidation of organic compounds offers a promising strategy for producing value-added chemicals through environmentally sustainable processes. A key challenge in this field is the development of electrocatalysts that are both effective and durable. In this study, we grow gold nanoparticles (Au NPs) on the surface of various phases of titanium dioxide (TiO 2 ) as highly effective electrooxidation catalysts. Subsequently, the samples are tested for the oxidation of benzaldehyde (BZH) to benzoic acid (BZA) coupled with a hydrogen evolution reaction (HER). We observe the support containing a combination of rutile and anatase phases to provide the highest activity. The excellent electrooxidation performance of this Au-TiO 2 sample is correlated with its mixed-phase composition, large surface area, high oxygen vacancy content, and the presence of Lewis acid active sites on its surface. This catalyst demonstrates an overpotential of 0.467 V at 10 mA cm -2 in a 1 M KOH solution containing 20 mM BZH, and 0.387 V in 100 mM BZH, well below the oxygen evolution reaction (OER) overpotential. The electrooxidation of BZH not only serves as OER alternative in applications such as electrochemical hydrogen evolution, enhancing energy efficiency, but simultaneously allows for the generation of high-value byproducts such as BZA.

As plastic waste pollution continues to pose significant challenges to our environment, it is crucial to develop eco-friendly processes that can transform plastic waste into valuable chemical products in line with the principles of green chemistry. One major challenge is breaking down plastic waste into economically valuable carbon resources. This however presents an opportunity for sustainable circular economies. In this regard, a flexible approach is presented that involves the use of supported-metal catalysts to selectively degrade polylactide waste using molecular oxygen. This protocol has several advantages, including its operation under organic solvent-free and mild conditions, simplicity of implementation, and high atom efficiency, resulting in minimal waste. This approach enables the chemical upcycling of polylactide waste into valuable chemicals such as pyruvic acid, acetic acid, or a mixture containing equimolar amounts of acetic acid and formaldehyde, providing a viable alternative for accessing key value-added feedstocks from waste and spent plastics., (© 2023 Wiley-VCH GmbH.)

Due to the huge amount of collected echo data caused by the working principle of synthetic aperture radar (SAR), the use of digital processing relies heavily on the performance of digital chips. Because of the limitation of Moore's law, the technology of digital signal processing exposes the limitation of computing speed and power consumption in the face of SAR processing. Against this background, the optical processing method based on the optical 4f system is introduced into SAR imaging. A spatial light modulator (SLM) is placed on the input surface and spectrum surface of the 4f system to load the echo data of the SAR and the matched filter function of the SAR. Using optical Fourier transform to realize the core calculation of SAR data processing can solve the difficulty of processing time-consuming due to the large amount of calculation. In the process of Fourier transform, instead of using a solid glass lens, we use a phase-type Fresnel lens diagram in the SLM to realize the function of Fourier, which avoids the need for special design of Fourier lens. It also greatly reduces the volume and weight of the whole machine, which provides a reference method for real-time imaging of spaceborne SAR.

Although covalent organic frameworks (COFs) have received extensive attention for biomedical research due to their unique properties, their application is still hindered by the challenges of incorporating COFs with functional biomolecules. Since peptides have shown advantages in biomedical applications, herein, we propose the functionalization of COFs with peptides by a polymer-assisted surface modification strategy. Furthermore, a method based on the peptide-functionalized COFs for protein detection has also been developed to demonstrate their application potential. With the help of the polymers, peptides and horseradish peroxidase are attached onto COFs with a high surface density, and the developed method has achieved simple and sensitive detection of the secreted protein acidic and rich in cysteine. We speculate that the facile method proposed in this work to prepare peptide-functionalized COFs can not only benefit protein detection but also promote more biomedical applications of COFs.

Electronic reconnaissance is to detect signals, extract their parameters, modulation types or direction of arrival and so on from a wide bandwidth range. It is difficult for digital signal processing device to process in real time under an ultra-wide bandwidth environment. This paper proposed a programmable optical system which can process signals from an instantaneous bandwidth up to 40GHz in real time. In the optical system, the signals are reconstructed at wavefront of a laser beam. The laser beam carrying signals passes through an optical system composed by lens, beam splitter, light modulator, etc. Signal processing operation is accomplished when laser beam arrives at a focal plane, and processing results are acquired by a high-speed camera. Typical pulse description words can be yielded from the results. The proposed optical system has a nano-second processing delay due to its meter-length light path.

The real-time processing of synthetic aperture radar (SAR) data has a high requirement for the processor, which is a difficult problem in SAR real-time processing. With the rapid development of optoelectronic devices, traditional electrical SAR data processing can be converted into optoelectronic processing to improve the processing speed. In this paper, a new type of optical device is proposed to improve the processing speed of SAR data. With the help of a spatial light modulator (SLM), the initial SAR signal and matched filter function are loaded on the input plane and spectrum plane of the 4f system, respectively. Using an optical lens with the function of the Fourier transform, the Fourier transform and inverse Fourier transform of the SAR signal are carried out to realize the fast imaging of SAR. In theory, the processing speed of SAR data is the speed of light. Compared with traditional methods such as the range-Doppler (RD) algorithm, it is no longer necessary to carry out a one-dimensional Fourier transform but to carry out matching filtering for the azimuth and range of the spectrum plane of 4f system at the same time. In this way, it is not necessary to introduce a cylindrical lens, only a spherical lens is needed to realize the Fourier transform imaging of SAR. Finally, a two-dimensional SAR processing optical system is built to obtain the SAR image in real time.

Transition metal phosphides (TMPs) are regarded as highly active electrocatalysts for the hydrogen evolution reaction (HER). However, traditional synthetic routes usually use expensive and dangerous precursors as P donors. The development of a low-cost and ecofriendly method for the synthesis of TMPs is significant for sustainable energy development. Herein, cobalt phosphides anchored on or embedded in a spirulina-derived porous N-doped carbon matrix (Co 2 P/NC) was fabricated by two-step hydrothermal treatment and carbonization method, which utilized the intrinsic C, N, and P of biomass cleverly as the sources of C, N, and P, respectively. As a result of the high surface area and porosity that enhance the mass-transfer dynamics, Co 2 P/NC shows good electrocatalytic activity at all pH values in the HER. This work not only provides a facile and effective method for the fabrication of TMP nanoparticles loaded onto carbon materials but also opens a new strategy for the utilization of the intrinsic ingredients of biomass for the preparation of other functional electrocatalysts., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)