Sodium alginate/sodium lignosulfonate hydrogel based on inert Ca2+ activation for water conservation and growth promotion.

Soil degradation has become a major global problem owing to the rapid development of agriculture. The problems of soil drought and decreased soil fertility caused by soil degradation severely affect the development of the agricultural and forestry industries. In this study, we designed sodium alginate (SA)/sodium lignosulfonate (SLS) hydrogel based on the activation and crosslinking of inert Ca2+. CaCO3 and SA were mixed, and then, inert Ca2+ was activated to prepare a gel with a stable structure and a uniform interior and exterior. The crosslinking activated by inert Ca2+ enhanced the stability of the hydrogel, and the optimal swelling rate of the hydrogel reached 28.91 g/g, thereby effectively improving the water-holding capacity of the soil (77.6-108.83 g/kg). SLS was degraded into humic acid (HA) and gradually released, demonstrating a positive growth-promoting effect in plant growth experiments. The SA/SLS hydrogel can be used for soil water retention and mitigation to significantly decrease the water loss rate of soil. This study will assist in addressing soil drought and fertility loss.

Preparation of Multicolour Solid Fluorescent Carbon Dots for Light-Emitting Diodes Using Phenylethylamine as a Co-Carbonization Agent.

Carbon dots (CDs), as a new type of photoluminescent nanomaterial, have attracted extensive attention in various fields because of their unique luminescence properties. However, CDs will exhibit fluorescence quenching in the solid state or aggregate state, which limits their application. In this paper, a unique strategy is proposed to regulate solutions to achieve multicolour fluorescence of CDs in the solid state. We report the successful preparation of orange, green and blue solid fluorescent CDs using citric acid, urea and phenylethylamine as precursors and methanol, ethanol and water as solvents, respectively. The solid-state fluorescence of CDs may be caused by the linkage of the phenylethyl structure to the surface of CDs during formation, which effectively disperses the CDs and prevents π-π interactions between graphitized nuclei. Meanwhile, multicolour solid fluorescent CDs are realized by adjusting the solvent in the preparation process. Based on the excellent fluorescence properties of CDs, orange, green and blue light-emitting diodes (LEDs) are prepared. A white LED (WLED) can be obtained by mixing the three colours of solid fluorescent CDs, which shows the application potential of CDs in display lighting equipment.

Solvent-Free Preparation of Tannic Acid Carbon Dots for Selective Detection of Ni2+ in the Environment.

Carbon dots (CDs) are widely used nanomaterials that not only exhibit good biocompatibility and photostability, but also benefit from a simple preparation process and easy functionalization, making them promising for broad applications in the fields of heavy metal ion detection and optoelectronic devices. Based on the excellent optical properties of CDs and the current situation of increasing energy shortages, this paper selects the natural polyphenolic compound tannic acid (TA) found in biomass materials as the carbon source and innovatively adopts a simple and convenient solvent-free pyrolysis method without auxiliary reagents or solvents. The CDs with good water solubility and certain fluorescence properties were directly prepared under the condition of high temperature, and the obtained CDs exhibited blue fluorescence, and a high QY of 35.4% was obtained at 300 °C. The analysis and results demonstrate the selectivity of these CDs for the detection of various metal ion solutions. In particular, these CDs are sensitive to Ni2+ and can be used as fluorescent sensors for the efficient and sustainable detection of Ni2+, whereas previous sensors were often specific to Fe3+ and Hg2+. Thus, a new sensing technique has been developed for the detection of Ni2+ to achieve more sensitive and rapid detection.

Palladium-mediated Suzuki-Miyaura Cross-Coupling Reaction of Potassium Boc-protected aminomethyltrifluoroborate with DNA-Conjugated aryl bromides for DNA-Encoded chemical library synthesis.

A mild reaction for DNA-compatible, palladium promoted Suzuki-Miyaura cross-coupling reaction of potassium Boc-protected aminomethyltrifluoroborate with DNA-conjugated aryl bromides has been developed efficiently. This novel DNA encoded chemistry reaction proceeded well with a wide range of functional group tolerance, including aryl bromides and heteroaryl bromides. Further, the utility our DNA conjugated aminomethylated arene products is demonstrated by reaction with various types of reagents (including amide formation with carboxylic acids, alkylation with aldehydes, and carbamoylation with amines) as would be desired for the production of a DNA encoded library.

DNA-Compatible Copper-Catalyzed Oxidative Amidation of Aldehydes with Non-Nucleophilic Arylamines.

We report a DNA-compatible protocol for synthesizing amides from DNA-bound aldehydes and non-nucleophilic arylamines including aza-substituted anilines, 2-aminobenzimidazoles, and 3-aminopyrazoles. The reactions were carried out at room temperature and provided reasonable conversions and wide functional group compatibility. The reactions were also successful when employing aryl and aliphatic aldehydes. In addition, qPCR and NGS data suggested no negative impact on DNA integrity after the copper-mediated oxidative amidation reaction.

Design of High-Entropy Alloy Coating for Cavitation Erosion Resistance by Different Energy-Induced Dynamic Cyclic Behaviors.

The dispute over the effect of cavitation heat on material surface intensifies the fuzziness of cavitation erosion (CE) mechanism and limits the development of protective materials. Here, an anti-CE Al10Cr28Co28Ni34 high-entropy alloy (HEA) coating with single face-centered cubic (FCC), prepared by high-velocity oxy-fuel (HVOF) spraying technologies, was designed by inducing mechanical and thermal energy-induced behaviors to transform or counteract each other. The results showed that, on the one hand, this coating underwent the refinement of the average grain size from 1.22 to 1.02 µm, the increase in dislocation density from 1.28 × 10-10 to 1.83 × 10-10 m-2, and the martensitic transformation from FCC to body-centered cubic (BCC) under the cavitation load; on the other hand, cavitation heat could indeed induce grain growth and realize structural relaxation, which confirmed that cavitation heat acting on the material surface at temperatures theoretically above 1206.28 K also played a significant role in the CE mechanism. That is, the surface microstructure of this coating was always in a dynamic cycle during the CE process. Therefore, the coating achieved the simultaneous absorption of mechanical impact energy and thermal energy released by the bubble collapse while effectively avoiding the overenrichment of crystal defects and finally exhibited a CE resistance 2 times better than that of the classical AlCrCoFeNi HEA coating. This design concept of inducing different energy restraints or neutralization through the special response behaviors of surface microstructure provides a completely new way for the development of CE-resistant materials.

Bandgap engineering control bifunctional MnxCd1-xS photocatalysts selectively reforming xylose to C3 organic acids and efficient hydrogen production.

The simultaneous reforming of biomass into high value-added chemicals and H2 production by water splitting in a green and environmentally clean way is a very challenging task. Herein, we demonstrate the design of bifunctional MnxCd1-xS photocatalyst with a controllable band gap by bandgap engineering. Bandgap engineering effectively regulates the oxidation and reduction capacity of materials. The design of photocatalysts with suitable conduction bands and valence bands makes the targeted conversion of xylose possible. Innovative conversion of xylose to glyceric acid, lactic acid, and propanoic acid. The optimized Mn0.7Cd0.3S catalyst showed excellent performance in the production of H2 (14.06 mmol·gcat-1·h-1, 29.9 times more than CdS and 351.5 times more than MnS), xylose conversion (90%), and C3 organic acid yield (59.2%) without cocatalyst and any scavengers under visible light irradiation. This work shows that a rational photocatalyst design can achieve efficient simultaneous production of high value-added chemicals and clean energy.

A Study on the Preparation and Cavitation Erosion Mechanism of Polyether Polyurethane Coating.

Polyurethane elastomers are anticipated to be applied in the field of cavitation erosion (CE) resistance, but their protection and damage mechanisms are not clear, which greatly restricts their further development. In this article, five polyether polyurethanes (PUx) with different crosslinking densities were prepared. Their mechanical properties, thermal properties, water absorption, surface morphology and chemical structure before and after CE tests were compared with ESEM, OM, TG-DSC, FTIR and XPS in detail. The results showed that with an increase in crosslinking density, the tensile strength of PUx increased first and then decreased, elongation at break and water absorption reduced gradually and thermal decomposition temperature and adhesion strength increased steadily. During the CE process, cavitation load aggravated the degree of microphase separation and made brittle hard segments concentrate on the coating surface; meanwhile, cavitation heat accelerated hydrolysis, pyrolysis, oxidation and the fracture of molecular chains. As a result, the mechano-thermal coupling intensified the formation and propagation of fatigue cracks, which should be the fundamental reason for the CE damage of polyurethane elastomer. PU0.4 exhibited the best CE resistance among the five coatings thanks to its good comprehensive properties and may find potential applications on the surface of hydraulic components.

Solvent-Free Pyrolysis Strategy for the Preparation of Biomass Carbon Dots for the Selective Detection of Fe3+ Ions.

Biomass carbon dots (BCDs) have the advantages of being nontoxic, low cost and simple to prepare, have excellent optical properties, good biocompatibility and stability, and therefore have broad application prospects in areas such as heavy metal ion detection and optoelectronic devices. Herein, a simple, green, solvent-free method of preparing BCDs was developed. CDs with certain fluorescence properties were prepared by a solvent-free pyrolysis method at different temperatures using two abundant components (cellulose and lignin) of biomass resources as carbon sources. Both the cellulose CDs prepared at 300°C and the lignin CDs prepared at 350°C exhibited high quantum yields of 11.7% and 23.4%, respectively, a result that was mainly due to the high degree of graphitization. The analysis and results demonstrated the selectivity of CDs for the detection of various metal ion solutions. In particular, CDs are sensitive to Fe3+ and can be used as a fluorescent sensor for the detection of Fe3+, providing a more efficient, sustainable alternative for metal ion detection.

Discovery of SARS-CoV-2 main protease covalent inhibitors from a DNA-encoded library selection.

Covalent inhibitors targeting the main protease (Mpro, or 3CLpro) of SARS-CoV-2 have shown promise in preclinical investigations. Herein, we report the discovery of two new series of molecules that irreversibly bind to SARS-CoV-2 Mpro. These acrylamide containing molecules were discovered using our covalent DNA-encoded library (DEL) screening platform. Following selection against SARS-CoV-2 Mpro, off-DNA compounds were synthesized and investigated to determine their inhibitory effects, the nature of their binding, and to generate preliminary structure-activity relationships. LC-MS analysis indicates a 1:1 (covalent) binding stoichiometry between our hit molecules and SARS-CoV-2 Mpro. Fluorescent staining assay for covalent binding in the presence of cell lysate suggests reasonable selectivity for SARS-CoV-2 Mpro. And lastly, inhibition of enzymatic activity was also observed against a panel of 3CLpro enzymes from different coronavirus strains, with IC50 values ranging from inactive to single digit micromolar. Our results indicate that DEL selection is a useful approach for identifying covalent inhibitors of cysteine proteases.

Preparation of solvent-free starch-based carbon dots for the selective detection of Ru3+ ions.

A simple, green, and solvent-free pyrolysis method for the preparation of starch-based carbon dots (CDs) was developed. The CDs prepared at 300 °C exhibited a highest quantum yield of 21.0%, which was mainly due to the high degree of graphitisation of the CDs. The CDs were selective for the detection of Ru3+ ion solutions.

Bioinspired Hydroxyapatite Coating Infiltrated with a Graphene Oxide Hybrid Supramolecular Hydrogel Orchestrates Antibacterial and Self-Lubricating Performance.

Hydroxyapatite (HA) bioceramic coating has been extensively applied for the modification of metallic implants to improve their biocompatibility and service life after implantation. Unfortunately, HA coating often suffers from high friction, severe wear, and bacterial invasion, which restrict its application in artificial joints. According to a bioinspired soft/hard combination strategy, a novel HA composite coating that is infiltrated with a vancomycin-loaded graphene oxide (GO) hybrid supramolecular hydrogel is developed via vacuum infiltration and a subsequent host-guest interaction-induced self-assembly process. The holes of textured HA ceramic coating act just like a "magic pocket", offering a stable container to form and store GO hybrid hydrogels and even to recycle wear debris as well. The drug-loaded hybrid hydrogels stored in textured HA coating possess a unique shear force and/or frictional heat triggered gel-sol transition and sustained drug release behavior, acting like the extrusion of synovial fluid during articular cartilage movement, leading to a remarkable self-lubrication, anti-wear performance, and promising antibacterial property against Staphylococcus aureus. The friction coefficient and wear rate of composite coating reduced by nearly five times and three orders of magnitude compared with textured HA coating, respectively, which benefited from the synergistic lubricate effect of cyclodextrin-based pseudopolyrotaxane supramolecular hydrogel and GO lubricants.

DNA-Compatible Click Reaction Employing In Situ Generated Azides from Boronic Acids.

An efficient method for the synthesis of DNA-conjugated 1,2,3-triazoles is copper (II) [Cu(II)-ß-cyclodextrin]-mediated Huisgen cycloaddition ("click reaction") of DNA-conjugated alkynes with azides. However, a diverse array of building blocks is required to produce useful DNA encoded libraries, and the commercial availability of azides is limited. The method described herein generates azides in situ from aryl borates and TMSN3 , which then further react with DNA-conjugated terminal alkynes. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Conjugation of PEG linker to DNA headpiece Basic Protocol 2: DNA conjugated terminal alkyne preparation Basic Protocol 3: DNA compatible one-pot click reaction Basic Protocol 4: LCMS monitoring.

Red, green, and blue light-emitting carbon dots prepared from gallic acid for white light-emitting diode applications.

Red, green, and blue CDs were successfully prepared by a solvothermal method using gallic acid as the raw material. The distinct optical features of these CDs are based on the differences in the size of their sp2-domains, which can be governed by reaction solvents.

Red Emission Carbon Dots Prepared by 1,4-Diaminonaphthalene for Light-Emitting Diode Application and Metal Ion Detection.

Carbon dots (CDs), as the most important type of carbon materials, have been widely used in many fields because of their unique fluorescence characteristics and excellent properties of biocompatibility. In previous studies, the fluorescence of CDs was mainly concentrated in the blue and green, whereas the red fluorescence was relatively less. Herein, we prepared efficient red-emitting CDs from 1,4-diaminonaphthalene using solvothermal methods. We discussed the effects of different solvothermal solvents on CDs. The results show that CDs prepared with octane and acetone as reaction media have the best fluorescence properties. The CDs dispersed in different organic solvents exhibited tunable emission across a wide spectrum from 427 nm to 679 nm. We further demonstrated the application of red light-emitting diode (LED) optoelectronics and fluorescence detection of Fe3+ in aqueous solution.

Red, green, and blue light-emitting carbon dots prepared from o-phenylenediamine.

Carbon dots (CDs), as the most important type of carbon-based material, have been widely used in many fields because of their excellent properties. In particular, multicolor fluorescent CDs with high photoluminescence quantum yield are the focus of active research. Herein, red, green and blue CDs (RGB CDs) were successfully synthesized by a solvothermal method from o-phenylenediamine under different reaction conditions. The RGB-CDs have stable optical properties and significant photoluminescence characteristics. Structural and elemental analyses propose a conjugated structure and the surface state of the CDs as the main causes for the different color emission of RGB-CDs. In addition, a white fluorescent CD solution was prepared by mixing these multicolor fluorescent CDs in appropriate proportions.

Application of high-efficiency green fluorescent carbon dots prepared by acid catalysis in multicolour LEDs.

Acidic reagents play an important role in the preparation of carbon dots (CDs). Therefore, we prepared efficient green fluorescent CDs by potassium bisulfate, acetic acid and hydrochloric acid catalysis and discussed why the acid catalyst induced a fluorescence redshift and improved the quantum yield of the CDs. Furthermore, the concentration-dependent photoluminescence behaviour of the CDs was characterized. CD/PVA composites emitting green to yellow light were obtained by exploiting the fluorescence tunability of CDs. Based on different light-emitting diode substrates, green, yellow and white light-emitting diodes with excellent performance were prepared.

Supramolecular hydrogel-infiltrated ceramics composite coating with combined antibacterial and self-lubricating performance.

Inspired by the structure and dynamic weeping lubricating mechanism of articular cartilage, a novel composite coating composed of a textured Y2O3-stabilized ZrO2 (YSZ) ceramics reservoir and silver nanoparticles (AgNPs) hybrid supramolecular hydrogel was developed on the basis of a soft/hard combination strategy. The precursor solution including the poly(ethylene glycol) (PEG)-modified AgNPs and α-cyclodextrins (α-CDs) could be infiltrated deep into (50-60 µm) the pores of a textured YSZ ceramics substrate by a vacuum infiltration method, in situ forming a supramolecular hydrogel within the pores through host-guest inclusion between α-CDs and PEG chains distributed onto the surface of AgNPs. The AgNPs hybrid hydrogel showed thixotropic and thermoresponsive gel-sol transition behavior, low cytotoxicity, and excellent drug-loading capacity, as well as significant antibacterial properties. The textured YSZ ceramics not only provided a hard supporting skeleton and stable reservoir to protect the supramolecular hydrogel from destruction under load-bearing or shear condition, but also allowed retaining the stimuli-responsive gel-sol transition property and drug-release capability of the infiltrated hydrogel, endowing the composite coating with excellent antibacterial properties, and self-lubrication and wear-resistance performance. The composite coating in this work brings a new insight into the design of antibacterial and self-lubricating ceramic coatings for artificial joint applications.

Cavitation erosion mechanisms in Co-based coatings exposed to seawater.

The cavitation erosion (CE) of most materials in seawater is more serious than in fresh water due to the onset of corrosion; however, in a previous study we reported results that contradict this widely accepted trend. In this research our objective is to provide fundamental insight into the mechanisms that may be responsible for these earlier results. To accomplish this objective, two types of Co-based coatings, prepared by high velocity oxygen fuel (HVOF) spraying system, were used to further investigate the underlying corrosion-mitigating CE mechanism in seawater. Accordingly, the influence of spraying parameters on microstructure, composition and mechanical properties of the coatings was analyzed on the basis of SEM, XRD, Raman spectroscopy, Vicker's hardness and nano-indentation results. Electrochemical corrosion tests were used to evaluate the corrosion behavior of the Co-based coatings. Their CE performances in seawater and deionized water were comparatively studied by a vibratory apparatus. Results demonstrated that a higher flame temperature facilitated the oxides formation with associated improvements in compactness, hardness and toughness of the coatings. The presence of alumina in combination with the oxides formed in-situ facilitated the formation of an oxidation film on surfaces, and effectively enhanced the charge transfer resistance of the coating, thereby significantly improving the corrosion resistance in seawater. Metallic Co was not only more easily oxidized but also more readily corroded than the alloyed Co. Compactness was identified as an important factor affecting CE resistance of coatings in deionized water, because defects facilitate the nucleation and eventual collapse of bubbles. Moreover, bubble collapse produced a transient high temperature spike in excess of 600 °C that also caused Co and Cr elements to oxidize. Because the CE tests were carried out in seawater, additional Co3O4 and Cr2O3 were generated owing to corrosion that more effectively increased the surface compactness and mechanical properties of the coatings. This behavior was particular notable for coatings with metallic Co and Cr, which should be why seawater corrosion could weaken the CE of Co-based coatings.

Synthesis of 1,2-Amino Alcohols by Photoredox-Mediated Decarboxylative Coupling of α-Amino Acids and DNA-Conjugated Carbonyls.

We report a DNA-compatible photoredox decarboxylative coupling of α-amino acids with carbonyl compounds to access DNA-encoded sp3-rich 1,2-amino alcohols. The reaction proceeds efficiently for a wide range of DNA-conjugated aldehydes and ketones and provides the desired 1,2-amino alcohols with conversions generally >50%. Additional utility of the developed protocol is demonstrated by one-pot cyclization of DNA-conjugated 1,2-amino alcohols into oxazolidiones and morpholinones. Lastly, qPCR and sequencing data analysis indicates no significant DNA damage upon photoredox decarboxylative coupling.