Preparation of bamboo-derived magnetic biochar for solid-phase microextraction of fentanyls from urine

In this study, a biochar-based magnetic solid-phase microextraction method, coupled with liquid chromatography–mass spectrometry, was developed for analyzing fentanyl analogs from urine sample. Magnetic biochar was fabricated through a one-step pyrolysis carbonization and magnetization process, followed by an alkali treatment. In order to achieve desired extraction efficiency, feed stocks (wood and bamboo) and different pyrolysis temperatures (300–700°C) were optimized. The magnetic bamboo biochar pyrolyzed at 400°C was found to have the greatest potential for extraction of fentanyls, with enrichment factors ranging from 58.9 to 93.7, presumably due to H-bonding and π–π interactions between biochar and fentanyls. Various extraction parameters, such as type and volume of desorption solvent, pH, and extraction time, were optimized, respectively, to achieve the highest extraction efficiency for the target fentanyls. Under optimized conditions, the developed method was found to have detection limits of 3.0–9.4 ng/L, a linear range of 0.05–10 μg/L, good precisions (1.9–9.4% for intrabatch, 2.9–9.9% for interbatch), and satisfactory recoveries (82.0–111.3%). The developed method by using magnetic bamboo biochar as adsorbent exhibited to be an efficient and promising pretreatment procedure and could potentially be applied for drug analysis in biological samples.     

The development of hollow multishelled structure: from the innovation of synthetic method to the discovery of new characteristics

Hollow multishelled structure(HoMS)is one of the most promising multifunctional structures.The high complexity of its structure makes the general and controllable synthesis of HoMS rather challenging.By integration of multidisciplinary knowledge,a great achievement in HoMSs has been obtained in the past decade.Especially,the developed sequential templating approach has significantly boomed the progress of HoMS in composition and structure diversity and application area.The implementation of the temporal-spatial ordering in HoMS makes it indispensable in solving the key scientific problems in energy conversion,catalysis and drug delivery areas.Further development in HoMSs with novel intricate structures will bring new understandings.In this review,we systematically introduce the development history of HoMSs,summarize the inspiration inherited from the previous research on hollow structures,and discuss the milestones in the development of HoMSs,with a focus on the sequential templating approach for HoMS fabrication,attractive temporal-spatial ordering property and dynamic smart behavior for advanced applications.We hope to reveal the inherent relationship between the precise synthesis of HoMS and its highly tunable compositional and structural characteristics,and point out its future direction to boost HoMS area further.     

Controlled electropolymerization based on self-dimerizations of monomers

Electropolymerization is one of the most important methodologies to synthesize and develop conducting polymers. The complexity of the polymerization mechanism, ion doping processes and structural defects are considered to be symbiotic and unavoidable, making the stagnant state and huge band gap with advanced interdisciplinary research fields and important applications in the last three decades. Herein, we provide a point of view into controlled electropolymerization by regioselective activation reactions of monomers, where self-dimerizations instead of self-electropolymerizations were utilized. The resulting dimers play a role in the connections between functional building blocks to form functional polymers on demand. This account highlights the typical findings in controlled electropolymerizations as a forum for discussing new opportunities in exploiting novel designs and applications.     

Suppression of charge imbalance via Li+-Mn4+ co-incorporated Sr2YSbO6 red phosphors for warm w-LEDs

Mn⁴⁺-activated double perovskite phosphors with composition diversity have presented excellent luminescent performances. However, the charge imbalance between Mn⁴⁺ and matrix cations would increase non-radiative recombination and reduce the structural stability. Here, novel high-efficiency stable Li⁺/Mn⁴⁺ co-incorporated Sr₂YSbO₆ red phosphors are successfully synthesized via a solid-state reaction method for warm w-LEDs, where the Li⁺ ions have the effect of charge balance for Sr₂YSbO₆:Mn⁴⁺ and reduce the non-radiative energy transfer among Mn⁴⁺ ions. It is demonstrated that the substitution of Li⁺–Mn⁴⁺ pairs for Sb⁵⁺ can enhance the bonding with low-shifted diffraction peaks and high emission intensity, and prolong the decay lifetime, compared with those of Mn⁴⁺ single-doped ones. Impressively, the thermal stability is enhanced to 89.72% from 84.61% at the original value of 303 K. Finally, a w-LED device based on the optimal phosphor Sr₂YSbO₆:0.01Mn⁴⁺/0.01Li⁺ red component exhibits a correlated color temperature of 4487 K and color rendering index of 80.2. Therefore, the incorporated Li⁺ ions serve as both charge compensator and co-activator in Mn⁴⁺-activated double perovskite phosphors with the aim of high luminescent performance and thermal stability.     

Recent advances in microbial fuel cell-based toxicity biosensors: Strategies for enhanced toxicity response

Microbial fuel cells (MFCs) have been extensively studied as self-powered toxicity biosensors; however, their applications are limited by the relatively poor toxicity responses. The toxicity responses are known to be related to the factors such as the resistance of species to toxicants, the bioavailability of toxicants and the type of sensing elements. Accordingly, some strategies have already been proposed to enhance the toxicity responses in the past several years, including the external resistance tuning, quorum sensing effect, shear stress control, nutrient level control, electrode material choice, sensing element choice, and cell configuration design. This work introduces and discusses these strategies, and the suggestion for future work is also provided finally.     

Polymer Electrolytes – New Opportunities for the Development of Multivalent Ion Batteries

Batteries, as highly concerned energy conversion system, have a great development prospect in various fields, especially in the field of energy powered vehicles. Multivalent ion batteries are getting more attention due to their low cost, high abundance in earth crust, high capacity and safety compared with Lithium batteries. Despite above advantages, several problems still need to be solved before multivalent ion batteries achieve large-scale application, such as interfacial parasitic reaction, anode passivation, and dendrites. The replacement of liquid electrolytes with gel polymer electrolytes (GPEs) which pose high safety, high mechanical strength and simplified battery system, is an effective strategy to inhibit dendrite growth and improve electrochemical performance. This review mainly discusses the advantages and challenges of multivalent ion batteries including zinc, magnesium, calcium and aluminum batteries. Meanwhile, the major targets of this review are introducing the recent developments and making a summary of the future trends of GPEs in the multivalent ion batteries.     

Predicting Dinitrogen Activation via Transition-Metal-Involved [4+2] Cycloaddition Reaction

As the strongest triple bond in nature, the N≡N triple bond activation has always been a challenging project in chemistry. On the other hand, since the award of the Nobel Prize in Chemistry in 1950, the Diels-Alder reaction has served as a powerful and widely applied tool in the synthesis of natural products and new materials. However, the application of the Diels-Alder reaction to dinitrogen activation remains less developed. Here we first demonstrate that a transition-metal-involved [4+2] Diels-Alder cycloaddition reaction could be used to activate dinitrogen without an additional reductant by density functional theory calculations. Further study reveals that such a dinitrogen activation by 1-metalla-1,3-dienes screened out from a series of transition metal complexes (38 species) according to the effects of metal center, ligand, and substituents can become favorable both thermodynamically (with an exergonicity of 28.2 kcal mol⁻¹) and kinetically (with an activation energy as low as 13.8 kcal mol⁻¹). Our findings highlight an important application of the Diels-Alder reaction in dinitrogen activation, inviting experimental chemists’ verification.     

The mosaic structure design to improve the anchoring strength of SiOx@C@Graphite anode

Silicon oxide (SiO_x)-based anodes have aroused great interest as the most promising alternative anode in the practical application of high-performance lithium-ion batteries. However, the electrochemical performance is inhibited because of the large volume change, and the electrode structure deteriorates during the cycling process, which hinders their practical application. In this article, a novel fabrication method for the synthesis of high-performance SiO_x@C@Graphite composites is presented. SiO_x particles are anchored on the graphite surface by chemical vapor deposition and compression molding. This structure makes up the shortcomings of poor electrical conductivity and poor bonding strength between SiO_x and graphite particles. It is beneficial to form a stable solid electrolyte interface and helps to maintain the structural integrity of electrode materials. As a result, the synthetic SiO_x@C@Graphite anode shows a high reversible capacity (2698.8 mA h), excellent cycle stability (about 76.9% capacity retention for 500 cycles) and a superior rate ability. Our research hopes to provide a new idea for improving the bonding strength of the surface coating.     

Palladium-based bimetallic catalysts for highly selective semihydrogenation of alkynes using ex situ generated hydrogen

Semihydrogenation of alkynes to alkenes is an important and fundamental reaction in many industrial and synthetic applications and often suffers low selectivity because of the overhydrogenation. Here, highly selective semihydrogenation of alkynes is achieved by using H₂ ex situ generated from formic acid dehydrogenation with palladium (Pd)-based bimetallic catalysts through a two-chamber reactor in this work, realizing efficient utilization of H₂ and selective production of alkenes under mild reaction conditions. The Pd-based bimetallic catalysts show excellent catalytic performances for semihydrogenation of alkynes (PdZn bimetallic catalyst) and dehydrogenation of formic acid (PdAg bimetallic catalyst) in the two-chamber reactor.     

Synthesis and characterization of amino-terminated phosphorous polyborosiloxane and its effect on flame retardancy of polymethacrylimide

In this study, a novel flame retardant, that is, amino-terminated phosphorous polyborosiloxane (N-PBSi), was synthesized via a two-step polymerization reaction. The product's chemical structure was characterized firstly by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. It was proved that the prepared N-PBSi was indeed amino terminated and contained multiple flame-retardant elements including P, B, and Si. Besides, based on the variation of its FTIR spectra from room temperature to 700 °C and the subsequent thermogravimetric results, there also showed that the resultant N-PBSi had desirable thermal stability. This is a prerequisite for preparing flame-retardant polymethacrylimide (PMI) as PMI synthesis requires a high temperature treatment process up to 160 °C. On this basis, the condition for N-PBSi synthesis was then optimized to obtain flame retardants with better quality and higher yield. According to the experiments, the reactant ratio and reaction time were recommended to be 1:1.33:3 and 6 h, respectively. To evaluate the effectiveness of N-PBSi further, the flame retardancy of PMI with N-PBSi grafted was then investigated. The UL-94 rating and limiting oxygen index value of the PMI with 15 wt.% of N-PBSi incorporated were tested to be V-0 and 27%, respectively, indicative of greatly enhanced flame-retardant properties. In addition, the flame-retardant mechanism of N-PBSi on PMI was also discussed. Given all of these, the prepared N-PBSi as a reactive and effective flame retardant was promising for PMI.