Utilizing CO2‐derived formaldehyde derivatives for fuel additive or polymer synthesis is a promising approach to reduce net carbon dioxide emissions. Existing methodologies involve converting CO2 to ...methanol by thermal hydrogenation, followed by electrochemical or thermochemical oxidation to produce formaldehyde. Adding to the conventional methanol oxidation pathway, we propose a new electrochemical approach to simultaneously generate formaldehyde derivatives at both electrodes by partial methanol oxidation and the direct reduction of CO2. To achieve this, a method to directly reduce CO2 to formaldehyde at the cathode is required. Still, it has been scarcely reported previously due to the acidity of the formic acid intermediate and the facile over‐reduction of formaldehyde to methanol. By enabling the activation and subsequent stabilization of formic acid and formaldehyde respectively in methanol solvent, we were able to implement a strategy where formaldehyde derivatives were generated at the cathode alongside the anode. Further mechanism studies revealed that protons supplied from the anodic reaction contribute to the activation of formic acid and the stabilization of the formaldehyde product. Additionally, it was found that the cathodic formaldehyde derivative Faradaic efficiency can be further increased through prolonged electrolysis time up to 50 % along with a maximum anodic formaldehyde derivative Faradaic efficiency of 90 %.
An electrochemical system for the paired electrosynthesis of formaldehyde derivatives through cathodic CO2 reduction and anodic methanol oxidation was constructed. At the cathode, the non‐reducible formic acid was activated by esterification to methyl formate, which was then reduced again to form stable formaldehyde derivatives.
The dispersion of a filler in a rubber matrix is a crucial parameter affecting the mechanical and dynamical properties of a rubber compound. It is the current issue of the rubber compounding industry ...because, most fillers are categorized as a mineral, while the rubber is an organic material. The surface modification of the filler has been accepted as an effective technique for the improvement of the abovementioned parameter. First, the surface premodification of commercial carbon black with a grade of N660 (CB) was implemented by four different oxidation methods. After that, among of used methods, the oxidation method using citric acid was selected to produce modified carbon black (CB‐Oxi) for further treatment. Subsequently, the coupling agent, Bis3‐(triethoxysilyl)propyl tetrasulfide (TESPT) was functionalized on the surface of CB‐Oxi to produce modified‐CB‐Oxi. Also, for comparison purposes, the TESPT functionalization was accomplished on untreated CB to form modified‐CB. The FTIR spectra of CB‐Oxi showed using the premodification method introduced the hydroxyl and carboxyl groups on the surface of CB. The correspondent spectra for modified‐CB‐Oxi confirmed the existence of silane groups on the surface of the carbon black. However, the mentioned silane groups were not observed on the surface of modified‐CB. The findings were strengthened by several characteristic techniques including, FESEM, XRD, EDS, CHNS elemental analysis, and RAMAN spectra. The FESEM graphs and elemental mapping showed homogeneous dispersion and uniform distribution of sulfur and silicon elements on the modified‐CB‐Oxi surface. According to RAMAN spectra, the disturbance in the structure of carbon black graphite was reduced after surface modification. modified‐CB‐Oxi is proposed as a potential substitute filler for current commercial carbon black in rubber compounding.
Modification of commercial carbon black.
Nucleic acids in biofluids are emerging biomarkers for the molecular diagnostics of diseases, but their clinical use has been hindered by the lack of sensitive detection assays. Herein, we report the ...development of a sensitive nucleic acid detection assay named SPOT (sensitive loop‐initiated DNAzyme biosensor for nucleic acid detection) by rationally designing a catalytic DNAzyme of endonuclease capability into a unified one‐stranded allosteric biosensor. SPOT is activated once a nucleic acid target of a specific sequence binds to its allosteric module to enable continuous cleavage of molecular reporters. SPOT provides a highly robust platform for sensitive, convenient and cost‐effective detection of low‐abundance nucleic acids. For clinical validation, we demonstrated that SPOT could detect serum miRNAs for the diagnostics of breast cancer, gastric cancer and prostate cancer. Furthermore, SPOT exhibits potent detection performance over SARS‐CoV‐2 RNA from clinical swabs with high sensitivity and specificity. Finally, SPOT is compatible with point‐of‐care testing modalities such as lateral flow assays. Hence, we envision that SPOT may serve as a robust assay for the sensitive detection of a variety of nucleic acid targets enabling molecular diagnostics in clinics.
A unimolecular self‐locked allosteric DNAzyme biosensor (named SPOT) is developed to enable sensitive detection (LOD: fM‐aM) of low‐abundance nucleic acids in a one‐pot, one‐step, preamplification‐free, isothermal detection manner. SPOT exhibits potent performance on miRNA‐based detection for cancer diagnostics and viral RNA‐based detection for SARS‐CoV‐2 infection diagnostics.
Polylactide (PLA) was melt blended with low amounts of poly (butylene adipate‐co‐terephthalate) (PBAT) using a simple reactive extrusion process herein, aiming to address the inherent brittleness of ...PLA without significantly compromising its stiffness. PLA/PBAT (90/10) blends with a small amount of peroxide (0.02 phr) and a second crosslinker agent triallyl isocyanurate (TAIC) were produced to explore the structure‐performance relationship evolution in reactive extrusion. The results showed that the PLA blend with an appropriate amount of TAIC (i.e., 0.3 phr) exhibited a remarkable increase in elongation at break, reaching as high as 96%. The sample with high elongation also demonstrated a high stiffness, boasting a Young's modulus of 2.4 GPa and a yield strength of 43 MPa. It was evident that the combination of enhanced compatibility and optimized homogeneous PBAT phase size of approximately 0.6 μm worked synergistically to enhance the toughness of PLA. Conversely, higher TAIC contents resulted in over‐crosslinking, despite considerable improvements in compatibility. This study offers a versatile, scalable, and practical method to prepare fully biodegradable PLA blends with high toughness.
Reactive extrusion of polylactide (PLA)/poly (butylene adipate‐co‐terephthalate) blends with a high PLA content of 90 wt% enables the production of biodegradable polymeric materials exhibiting enhanced mechanical properties, including an elongation at break of 96%.
Abstract The structure and properties of incompatible polylactide (PLA)/polyamide elastomer (PAE) blends were tailored by a chain extender specifically the styrene–glycidyl acrylate copolymer Joncryl ...ADR4368 (ADR). Various PLA/PAE/ADR blends with different compositions were prepared by melt blending, and their morphology, crystallization behavior, and mechanical and the shape memory properties were systematically investigated. The results showed a uniform dispersion of PAE particles in the PLA matrix for the PLA blends with a reduction in particle size upon the addition of ADR. The crystallization of PLA was retarded, which was confirmed by a decrease in the melt crystallization temperature and an increase in cold crystallization temperature in the PLA/PAE/ADR blends. Rheological analysis showed an improvement in the melt elasticity of the PLA/PAE binary blend due to the presence of ADR, possibly attributed to the formation of long‐chain‐branched copolymers at the interface. Notably, the PLA/PAE/ADR blend exhibited superior toughness, featuring an elongation at break of 288% and a notched impact strength of 37 kJ·m −2 , along with a high shape memory fixation rate and recovery rate when the ADR content was 1 wt%. Furthermore, the underlying toughening mechanism was elucidated. This work may offer an industrially scalable relevant model to fabricate high‐performance PLA materials.
The construction of platinum (Pt) atomic layers is an effective strategy to improve the utilization efficiency of Pt atoms in electrocatalysis, thus is important for reducing the capital costs of a ...wide range of energy storage and conversion devices. However, the substrates used to grow Pt atomic layers are largely limited to noble metals and their alloys, which is not conducive to reducing catalyst costs. Herein, low‐cost chromium nitride (CrN) is utilized as a support for the loading of epitaxial ultrathin Pt atomic layers via a simple thermal ammonolysis method. Owing to the strong anchoring and electronic regulation of Pt atomic layers by CrN, the obtained Pt atomic layers catalyst (containing electron‐deficient Pt sites) exhibits excellent activity and endurance for the formic acid oxidation reaction, with a mass activity of 5.17 A mgPt−1 that is 13.6 times higher than that of commercial Pt/C catalyst. This novel strategy demonstrates that CrN can replace noble metals as a low‐cost substrate for constructing Pt atomic layers catalysts.
Pt atomic layers catalysts with electron‐deficient Pt sites and epitaxial strain are successfully grown on low‐cost CrN nanoparticles via a facile thermal ammonlysis method. The Pt atomic layers on CrN electrocatalyst deliver outstanding activity and durability for the formic acid oxidation reaction, guiding the development of low‐cost Pt‐based catalysts for various applications.
Ring‐opening of phenol in wastewater is the pivotal step in photocatalytic degradation. The highly selective generation of catalytical active species (•OH) to facilitate this process presents a ...significant scientific challenge. Therefore, a novel approach for designing photocatalysts with single‐atom containment in metal‐covalent organic frameworks (M‐COFs) is proposed. The selection of imine‐linked COFs containing abundant N and O‐chelate sites provides a solid foundation for anchoring metal atom. These dispersed metal atom possess rapid accumulation and transfer capabilities for photogenerated electrons, while the periodic π‐conjugated structure in 2D‐COFs establishes an effective platform. Additionally, the Lewis acid properties of imine bonds in COFs can enhance the adsorption capacity toward gases with Lewis base properties, such as O2 and N2. It is demonstrated that the Pd2+@Tp‐TAPT, designed based on this concept, exhibits efficient oxygen adsorption and follows the reaction pathway of O2→•O2−→H2O2→•OH with high selectivity, thereby achieving completely degradation of refractory phenol through photocatalysis within 10 min. It is anticipated that the selective generation of catalytic active species via advanced material design concepts will serve as a significant reference for achieving precise material catalysis in the future.
Metal‐covalent organic frameworks with metal single‐atom coordination (Pd2+@Tp‐TAPT) with high yield of •OH through an optimal conversion way has high activity in photodegradation of phenolic pollutants (10 ppm phenol within 10 min) and high selectivity in photocatalytic nitrogen fixation (189.63 µmol g−1 h−1 for NH4+), which provides guidance for the application of photocatalytic technology in environmental remediation and energy storage.
Abstract In this study, paper coated with a polyamide film containing a molecularly imprinted polymer (MIP) of benzalkonium chloride (BKC) is prepared. Its BKC adsorption ability and selectivity for ...BKC adsorption are investigated. The MIP is prepared by agitating an ethylenediamine solution containing an azo initiator, BKC as a template material, and methacrylic acid (MAA) as the functional monomer. First, filter paper soaked in this mixture is impregnated with a cyclohexane solution of terephthaloyl chloride and a BKC–MAA–MIP‐containing polyamide film is prepared on the surface of the paper. Paper containing BKC–MAA–MIP adsorbs BKC. The paper with the highest BKC removal efficiency is prepared under the following conditions: 4 mL MAA functional monomer, 2.5 w/v% ethylenediamine, and 10 min MIP synthesis time. The paper with BKC–MAA–MIP selectively adsorbs BKC from a solution containing BKC, tetracycline hydrochloride, and caffeine. Thus, a polyamide film containing BKC‐MAA‐MIP formed on paper can effectively and selectively remove BKC from aqueous environments.
For the purpose of the development of ultrahigh molecular weight polyethylene (UHMWPE) fibers with improved tensile properties, the stearic acid (SA) was added to the gel spinning of UHMWPE and acted ...as a lubricant film. SA addition was intended to be 0.2, 0.4, 0.6, 0.8, and 1.0 wt% of UHMWPE for forming the SA modified UHMWPE fibers. The tensile properties, thermal properties, crystallization properties, and orientation properties of the prepared UHMWPE fibers were systematically investigated. Results show that there is a more significant tensile property for UHMWPE fibers as SA addition is 0.6 wt%. Their tensile strength and tensile modulus reach 32.86 and 1580.89 cN/dtex, which are raised to an extent of 12.0% and 7.7%, respectively, compared with UHMWPE fibers alone. Moreover, the thermal properties, crystallization properties, and orientation properties of the prepared UHMWPE fibers are enhanced observably when the SA addition is 0.6 wt%.
For the purpose of the development of ultrahigh molecular weight polyethylene (UHMWPE) fibers with improved tensile properties, the stearic acid (SA) was added to the gel spinning of UHMWPE and acted as a lubricant film. The tensile strength of UHMWPE fibers with 0.6 wt% SA is able to attain 32.86 cN/dtex, increased by 12.0% in comparison with neat UHMWPE fibers. Moreover, the thermal properties, crystallization properties, and orientation properties of the prepared UHMWPE fibers are enhanced observably when the SA addition is 0.6 wt%.
Accurately locating an indoor unknown radio emitter (URE) is a challenging target to ensure telecommunication security. The URE positioning method based on received signal strength difference (RSSD) ...has attracted considerable attention due to the advantage of not being affected by transmit power and frequency. However, the RSSD-based fingerprint technique cannot accurately express the constraint equations between signal characteristics and geographic coordinates because of redundant databases and false matching. In this paper, a novel RSSD-based indoor positioning method using factor graph (FG) for an URE is proposed to improve positioning accuracy and reduce computational complexity. Firstly, the databases are reconstructed by singular value decomposition (SVD) to eliminate redundant factor nodes. Secondly, Pearson correlation coefficient (PCC) is utilized to determine the sub-positioning area. Combing SVD with PCC, the hyperplane equations are reconstructed to build an optimized FG model, called SP-FG. Considering simulation and experiment, the proposed SP-FG algorithm improves the cumulative distribution function (CDF) of average positioning error within 0.5 m by 10% and 14% compared with conventional FG algorithm and K-nearest neighbor (KNN) algorithm, respectively. In addition, this paper discusses the superiority of proposed SP-FG algorithm in positioning accuracy under different reference side lengths, access point (AP) coordinates and numbers.
