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In this study, we developed an in-package colorimetric paper to monitor the ripeness of kiwifruit by detecting the release of aldehydes. Strongly hydrophobic composite films were prepared using chitosan as the matrix and beeswax as an additive. A piece of cellulose paper containing methyl red and bromocresol violet as color indicators was heat-sealed between two hydrophobic films to protect the indicators from the effects of fruit respiration and transpiration. The nucleophilic addition reaction between aldehydes and OH− (Cannizzaro reaction) changes the pH in the paper and triggers a color change in the indicators. As the kiwifruit ripens, the colorimetric paper changes from bluish-purple to dark red and then gradually to red. A mobile phone application was further used to measure the RGB values and link them to kiwifruit ripeness. This intelligent paper can be used for the accurate and convenient monitoring of produce in real time. [ABSTRACT FROM AUTHOR]

Interest in connecting Chemical Reactions Network Theory (CRNT) and evolutionary game theory (EGT) arise viewing the tools of network in the analysis of evolutionary games. Here, the evolution of population species is studied as a biological phenomenon and describing the rate of such changes through a replicator system becomes a focus. A set of polynomial kinetics (POK) may then be introduced for the realization of this replicator system and this is based on the polynomial payoff functions defined in the game. These polynomial kinetics result in polynomial dynamical systems of ordinary differential equations, which are used in analyzing strategies that prove beneficial under certain conditions. From the CRNT point of view, it now becomes interesting to study a superset of POK, which we call poly-PL kinetics (PYK). This set is formed by getting nonnegative linear combinations of power law functions. Thus, PYK contains the set PLK of power law kinetics as mono-PL kinetics with coefficient 1. Seeing this connection between CRNT and EGT and what are known about power law kinetics, we take an interest in studying PYK systems. This paper aims to analyze different ways of transforming PYK to PLK in order to explore some approaches for CRNT analysis of PYK systems. Specifically, we study a network structure-oriented transformations using the S-invariant term-wise addition of reactions (STAR) Via Reaction Vector Multiples (RVM) that transform PYK to PLK systems. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: This paper presents the first general examples of palladium‐catalyzed desulfinative cross‐coupling reaction of polyhalogenated aryl triflates with aryl sulfinate salts showing an inversion of the conventional reactivity order of C—Br > C—Cl > C—OTf. The catalyst system, comprising of Pd(OAc)2 and tBuPhSelectPhos, exhibited excellent catalytic reactivity and chemoselectivity toward this reaction. This reaction had a wide range of substrate scopes and provided a simple and efficient method for the construction of functionalized biaryl motifs. Notably, the C—H···Pd interaction from the methine hydrogen of the C2‐cyclohexyl group of the indolyl phosphine ligand with the Pd center may contribute a key factor in reactivity and chemoselectivity. Assisting with density functional theory (DFT) calculations, the results revealed that the oxidative addition step in this reaction was a controlling‐chemoselectivity step. [ABSTRACT FROM AUTHOR]

Carbon–carbon bond formation is one of the most important tools in synthetic organic chemists' toolbox. It is a fundamental transformation that allows synthetic chemists to synthesize the carbon framework of complex molecules from inexpensive simple starting materials. Among the many synthetic methodologies developed for the construction of carbon–carbon bonds, organocopper reagents are one of the most reliable organometallic reagents for this purpose. The versatility of organocuprate reagents or the reactions catalyzed by organocopper reagents were demonstrated by their applications in a variety of synthetic transformations including the 1,4-conjugate addition reactions. Sulfur-containing heterocyclic compounds are a much less studied area compared to oxygen-containing heterocycles but have gained more and more attention in recent years due to their rich biological activities and widespread applications in pharmaceuticals, agrochemicals, and material science. This paper will provide a brief review on recent progress on the synthesis of an important class of sulfur-heterocycles-2-alkylthiochroman-4-ones and thioflavanones via the conjugate additions of Grignard reagents to thiochromones catalyzed by copper catalysts. Recent progress on the synthesis of 2-substituted thiochroman-4-ones via alkynylation and alkenylation of thiochromones will also be covered in this review. [ABSTRACT FROM AUTHOR]

The addition reaction of interelement compounds with heteroatom–heteroatom single bonds to unsaturated bonds under photoirradiation is an important method for the efficient and atom-economical construction of carbon–heteroatom bonds. However, in practice, the desired addition reaction is sometimes unable to proceed as expected due to the low efficiency of the desired addition reactions or the preferential polymerization of unsaturated compounds. In this study, by combining an interelement compound with homologous heteroatom compounds as a catalyst, we succeeded in suppressing the polymerization of the unsaturated compounds and in attaining a highly selective carbon–heteroatom bond formation through the desired addition reaction. In this paper, we have examined in detail whether such a "catalytic radical reaction" proceeds for unsaturated compounds and found that the dithiolation of some unsaturated compounds (i.e., vinylic ethers, styrenes, and isocyanides) could proceed with the assistance of (PhSe)2 under light. The developed methods in this study are expected to have strong implications in the fields of radical chemistry, heteroatom chemistry, synthetic organic chemistry, and catalyst chemistry as atom-economical methods for carbon–heteroatom bond formation. [ABSTRACT FROM AUTHOR]

Radical reactions are powerful in creating carbon–carbon and carbon–heteroatom bonds. Designing one-pot radical reactions with cascade transformations to assemble the cyclic skeletons with two new functional groups is both synthetically and operationally efficient. Summarized in this paper is the recent development of reactions involving radical addition and cyclization of dienes, diynes, enynes, as well as arene-bridged and arene-terminated compounds for the preparation of difunctionalization cyclic compounds. Reactions carried out with radical initiators, transition metal-catalysis, photoredox, and electrochemical conditions are included. [ABSTRACT FROM AUTHOR]

Nanomaterials have been extensively used in several applications in the past few decades related to biomedicine and healthcare. Among them, nanogels (NGs) have emerged as an important nanoplatform with the properties of both hydrogels and nanoparticles for the controlled/sustained delivery of chemo drugs, nucleic acids, or other bioactive molecules for therapeutic or diagnostic purposes. In the recent past, significant research efforts have been invested in synthesizing NGs through various synthetic methodologies such as free radical polymerization, reversible addition-fragmentation chain-transfer method (RAFT) and atom transfer radical polymerization (ATRP), as well as emulsion techniques. With further polymeric functionalizations using activated esters, thiol–ene/yne processes, imines/oximes formation, cycloadditions, nucleophilic addition reactions of isocyanates, ring-opening, and multicomponent reactions were used to obtain functionalized NGs for targeted delivery of drug and other compounds. NGs are particularly intriguing for use in the areas of diagnosis, analytics, and biomedicine due to their nanodimensionality, material characteristics, physiological stability, tunable multi-functionality, and biocompatibility. Numerous NGs with a wide range of functionalities and various external/internal stimuli-responsive modalities have been possible with novel synthetic reliable methodologies. Such continuous development of innovative, intelligent materials with novel characteristics is crucial for nanomedicine for next-generation biomedical applications. This paper reviews the synthesis and various functionalization strategies of NGs with a focus on the recent advances in different biomedical applications of these surface modified/functionalized single-/dual-/multi-responsive NGs, with various active targeting moieties, in the fields of cancer theranostics, immunotherapy, antimicrobial/antiviral, antigen presentation for the vaccine, sensing, wound healing, thrombolysis, tissue engineering, and regenerative medicine. [ABSTRACT FROM AUTHOR]

• Inconel 625 filling powders with different amounts of pure Zr addition are used to braze SiC ceramic. Sound SiC joints are obtained at 1400 °C. • Zr is beneficial in suppressing the formation of graphite, which is a mechanically detrimental product of the reaction between Ni and SiC. When Zr addition reaches 40 wt%, the interface shows no sign of graphite. • Thermodynamic calculations prove that Zr's activity surpasses that of Ni as the Zr content increases. Zr replaces Ni as the dominating element that reacts with SiC. A dense and consecutive ZrC layer is thus formed along the interface. • The room-temperature shear strength of the SiC joint with no graphite reaches 81.97 MPa, which is almost three times higher than that of the joint with graphite. Ni-based alloys are believed to be the most suitable brazing fillers for SiC ceramic application in a nuclear environment. However, graphite, which severely deteriorates the mechanical property of the joint, is inevitable when Ni reacts with SiC. In this paper, Different amounts of Zr powders are mixed with Inconel 625 powders to braze SiC at 1400 °C. When Zr addition reaches 40 wt%, the brazed seam confirms the absence of graphite. This research proves that Zr can avoid the graphite's formation by suppressing Ni's activity. The room-temperature shear strength of the joint with graphite's absence is tested to be 81.97 MPa, which is almost three times higher than that of the joint with graphite. The interfacial reaction process and mechanism of the SiC joint are investigated and explained in this paper using thermodynamic calculations. [ABSTRACT FROM AUTHOR]

Tremella polysaccharide (TP), one kind of green natural polysaccharide, exhibits different superior physical properties, which is a good choice to construct environmental‐friendly hydrogels. In the present study, TP hydrogels were designed with a "one‐step" approach, which via simply mixing TP solutions with different concentration of N,N‐methylenebis(acrylamide) (MBA) in NaOH/H2O solvent system. The experimental results showed that the NaOH concentration (1 %, 5 %, 10 %) and MBA concentration (6 mg/mL, 12 mg/mL and 18 mg/mL) had important influence on the gelation process of TP‐MBA hydrogels. When the concentrations of NaOH and MBA were 5 % and 18 mg/mL, respectively, the TP‐MBA hydrogel presented the shortest gelation time (2.5 h) and highest crosslinking density. Besides, the hydrogel formation mechanism was determined which suggested that the addition reaction between the −OH groups of tremella polysaccharide and the −C=C− bonds of MBA contributed to the formation of TP‐MBA hydrogels. In conclusion, this paper introduced a simple, efficient and green method for preparation of tremella polysaccharide‐based hydrogels. [ABSTRACT FROM AUTHOR]

In order to study the effect of microcrystalline cellulose on the reaction kinetics of polyurethane, in this work, the multi-scale microcrystalline cellulose was added to the foaming system of multifunctional polyether and multifunctional MDI polyurethane. While the chemical reaction was carried out, it was found through in situ FTIR combined with in situ rheological analysis that what was different from the usual inorganic fillers, the hydroxyl on the surface of the microcrystalline cellulose could preferentially react with MDI to generate urethane under the action of the catalyst. In the initial 5–6 min of the reaction, the reaction of soft segment chain growth was the main reaction. Then the main reaction quickly converted to the cross-linking reaction, which greatly increased the viscosity of the system. The addition of microcrystalline celluloses accelerated the improvement of the cross-linking degree and viscosity of the system. The higher the surface hydroxyl content of microcrystalline cellulose, the more significant this trend become. In addition, although the amount of microcrystalline cellulose added was different, the ratio of the reaction rate of the isocyanate group with the hydroxyl group and the amine group eventually tended to be constant, which indicated that there was a stable reactivity rate in the gradual addition reaction during the cross-linking reaction. Combined with SEM analysis, it was found that 25–60 μm microcrystalline cellulose with large hydroxyl content could act as a nucleating agent when the addition amount was less than 0.1%, which was beneficial to increase the cell density and reduce the pore size and improved the impact performance of the foam. The microcrystalline cellulose with a length of more than 90 μm continuously penetrated through several cell walls and destroyed integrity of the cell structure, which would consequently reduce the impact strength of the foam. This paper provided theoretical guidance for polyurethane modified by microcrystalline cellulose. [ABSTRACT FROM AUTHOR]

Amides are common molecules which are most often prepared using benzotriazole oxide coupling reagents. Such amides can be derivatised with compounds that contain a triple carbon–carbon bond in order to facilitate easy introduction of the amide fragment into a target molecule via cycloaddition reactions. In this paper, a previously unknown tandem reaction consisting of amide coupling and hydroamination of a triple C–C bond is described. The reaction occurs when the TBTU/HOBt coupling reagent pair is used for coupling of propiolic acid with mono-Boc-diaminocyclohexane. The hydroamination can be circumvented by using COMU as the coupling reagent. The addition reaction was further explored by using methyl propiolate with TBTU/HOBt which yielded a plethora of different products including O- and N-addition products and also a product of formal methyl propiolate dimerization. Due to high symmetry and low number of non-equivalent protons and carbons, most of the products were difficult to characterise by NMR spectroscopy, so it was necessary to obtain X-ray single crystal structures for most of them. In addition, the identification of the products was further supported by very good agreement of NMR spectra collected experimentally with NMR spectra calculated by DFT. [ABSTRACT FROM AUTHOR]

The study of isolated atoms or molecules inside a fullerene cavity provides a unique environment. It is likely to control the outer carbon cage and study the isolated species when molecules or atoms are trapped inside a fullerene. We report the Diels–Alder addition reaction of 9,10-dimethyl anthracene (DMA) to H2@C60 while 1H NMR spectroscopy is utilized to characterize the Diels–Alder reaction of the DMA with the fullerene. Through 1H NMR spectroscopy, a series of isomeric adducts are identified. The obtained peaks are sharp, precise, and straightforward. Moreover, in this paper, H2@C60 and its isomers are described for the first time. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitriding reaction and combustion of Al-Li alloy with tiny Li contents in N 2 was investigated. • Nitriding reaction temperature decreased from 853 °C for Al to 245 °C for Al-2.5Li alloy. • Intermediate nitriding products of Al-Li revealed key cracks and loose "island" structures. • Thermal nitriding reaction of Al-Li alloy was significantly faster than that of pure Al. • Metal Li can significantly improve the ignition and combustion performance of Al in N 2. • Combustion mechanism of Al-Li alloy and pure Al in N 2 were discussed and compared. For aluminum-based alloy particles, the addition of alloying element lithium (Li) with the properties of a high chemical activity and a low melting/boiling point can significantly improve the thermo-reactive properties of aluminum (Al) particles. To further reveal the combustion mechanism, this paper presents the nitriding reaction and combustion characteristics of Al-Li alloy in nitrogen (N 2) through thermogravimetric analysis and differential scanning calorimetry (TG-DSC) analysis at a low heating rate and laser-induced ignition experiments at a high heating rate, considering the influences of two kinds of Li contents (1.0 wt% @ Al-1.0Li and 2.5 wt% @ Al-2.5Li) on these characteristics and making a comparison to the counterpart Al. Al-Li alloy powders as-prepared by gas atomization method showed the texture of the Li-rich eutectic phase compounds on the surface by scanning electron microscope (SEM) characterization. The TG-DSC results demonstrated that the thermal nitriding reaction of Al-Li alloy in N 2 was significantly faster than that of pure Al. The nitriding reaction temperature decreased from 853 °C for pure Al to 245 °C for Al-2.5Li alloy with a reduction of 71 %. The final weight gain of Al-2.5Li alloy was almost three times higher than that of pure Al in N 2. The SEM photograph of intermediate nitriding products revealed that the cracks and loose "island" structures in the Li-rich zone on the Al-Li surface were the key to preventing the formation of a "passivation effect" into Al and promoting N 2 uptake during melting. In addition, Li also acts as a catalytic carrier and "oxygen absorber" to enhance the Al-N reaction. The combustion of single Al-Li alloy microparticles induced by laser showed two stages: preheating and rapid nitriding. Al-Li alloy particles were ignited more rapidly and showed typical gas-phase / surface combustion modes different from pure Al. According to these findings, the combustion mechanism was proposed to help guide the development of Al-based solid propellants containing Li and the synthesis of AlN/Al composites in nitrogen-rich environments. [ABSTRACT FROM AUTHOR]

• A novel fluorescent probe TPN-DP was developed for the detection of HSO 3 −. • TPN-DP exhibited high sensitivity, and excellent selectivity for HSO 3 −. • Real-time imaging of HSO 3 − was successfully achieved in plant and zebrafishes. Sulfur dioxide (SO 2) and its derivative bisulfite (SO 3 2−/HSO 3 −) have a serious impact on the human health and environment. Therefore, the development of highly sensitive and specific detection methods for SO 2 and its derivative is of great significance for environmental monitoring, food safety, and related disease research. In this paper, probe TPN-DP based on the triphenylamine fluorophore was developed to enable the imaging and detection of HSO 3 − in plant and zebrafish. In PBS buffer solution, the designed probe TPN-DP can react with HSO 3 − by highly selective nucleophilic addition reaction, leading to a sensitive change in the color of probe TPN-DP solution from pink to colorless. The changes in fluorescence and color can be easily recognized by the naked eye. Moreover, probe TPN-DP exhibited a fast response time of 8 min, high sensitivity of 19.4 nM, and excellent selectivity for sensing HSO 3 −. With the help of probe TPN-DP, the detection of HSO 3 − was successfully achieved in water sample and various biological systems, including onion epidermal cells, tobacco seedling roots, and zebrafish. These findings not only provide valuable insights into the biological role of HSO 3 − but also offer a promising analytical method for efficient HSO 3 − recognition. [Display omitted] [ABSTRACT FROM AUTHOR]

As an important branch of the Michael addition reaction, the aza‐Michael addition cascade reaction has been developed rapidly in recent years. This is because the reaction serves as an important method for effectively constructing functionalized C−N bonds, which can be widely used in the synthesis of chiral drugs and their intermediates and natural products. Given the importance of this topic, this review highlights the recent developments of aza‐Michael addition triggered cascade reactions in asymmetric synthesis, including aza‐Michael/Michael, aza‐Michael/Aldol, aza‐Michael/Henry, aza‐Michael/hemiacetal, aza‐Michael/Mannich, aza‐Michael/alkylation, aza‐Michael/cyclization, aza‐Michael/ring‐opening, aza‐Michael‐IED/HAD, aza‐Michael/INCR, and aza‐Michael/1,6‐conjugate addition reactions. In this paper, the reaction mechanism and derivatization experiments of different reactions are timely introduced to provide a more comprehensive theoretical basis for subsequent studies. [ABSTRACT FROM AUTHOR]

The paper presents results of thermokinetic investigation of the hazard-type reaction of Norwegian and Australian ilmenite ores with sulfuric acid, modified by the addition of elemental sulfur, to increase the process safety in industrial conditions. In the reactions of both ilmenite ores the addition of sulfur caused a reduction of the thermal power generated in the reaction and a decrease in the value of the thermokinetic parameter ΔTmax/Δτ for almost the whole range of initial concentrations of sulfuric acid. It was also found that the addition of sulfur to the reaction did not negatively affect the degree of ilmenite leaching. The interpretation of the obtained thermokinetic curves allowed to determine safe process conditions for both types of titanium raw materials. [ABSTRACT FROM AUTHOR]

In large-scale turbulent flame simulations, the exploitation of detailed chemistry and transport models often necessitates expensive memory and CPU requirements. To maintain the practicality and flexibility of such simulations, the combustion chemistry is commonly represented by reduced reaction mechanisms. The present paper describes the development of such a reduced short kinetic scheme for high-temperature oxidation of n-heptane suitable for application in complex turbulent flame simulations. Through a combination of the directed relation graph and quasi-steady state approximation methodologies, a skeletal 65-species kinetic model is formally reduced down to a 25-species derivative suitable for atmospheric lean to stoichiometric conditions. Further removal of appropriate reactions and species is facilitated by using the reaction path flux analysis, yielding a short chemical scheme of 25 species and 69 reactions. Particular attention is given to avoid addition of lumped reactions (for all isomer compounds) and artificial kinetic rates expressed as nonlinear algebraic combinations of excluded elementary steps. In addition, most of the original radical reaction pathways are duly preserved, and an adequate number of intermediate lighter-chain hydrocarbon species is represented in the reduced scheme to ensure a proper breakdown and oxidation of the main hydrocarbon. A series of 0D and 1D propagating and counterflowing premixed flames and axisymmetric coflowing laminar jet flames are computed throughout an iterative validation procedure. Complementary computations with the 65-species base scheme, as well as available experimental data are exploited for the assessment of the optimization effort. The comparisons demonstrate that the derived scheme ensures satisfactory agreement with these data over the investigated parameter space. [ABSTRACT FROM AUTHOR]

Parametric measurements of pulsed output energy from the four-level exciplex pumped alkali laser (XPAL) for Cs-Ar, Cs-Kr, and Cs-Xe as a function of input pump energy and temperature show a strong dependence on temperature. All three Cs-rare gas mixtures show a D2 line laser performance increase with temperature towards a peak efficiency, followed by a decrease as temperature is increased beyond a peak performance point temperature. Prior simulations of Cs-Ar XPAL measurements indicated that energy pooling from the 62P3/2 state of Cs was significant at higher temperature and it was hypothesized that the addition of temperature-dependent reaction rates may be important. This paper presents new BLAZE Multiphysics™ simulations using temperature-dependent energy pooling reaction rates baselined to available experimental rate data. Also included are photoionization and Penning ionization reactions. These new calculations for Cs-Ar and Cs-Xe (Cs-Kr not yet simulated) show that the inclusion of temperature-dependent energy pooling rates and the subsequent onset of significant ionization can explain the rise and fall of XPAL performance with temperature with reasonable accuracy. Further, while Cs-Xe has a much stronger absorption characteristic than Cs-Ar, simulations show that the energy well present in the Cs-Xe state increases the fraction of the Cs-Xe B-state relative to the Cs-Ar B-state, thereby resulting in energy output levels of Cs-Xe similar to that of Cs-Ar. [ABSTRACT FROM AUTHOR]

This paper presents a detailed theoretical investigation on the interaction between methylmethoxy (CH3OCH2) and nitrogen monoxide (NO) during thermal oxidation of dimethyl ether (DME). The calculated results indicate that the CH3OCH2 + NO reaction proceeds by the addition of N atom of NO to CH3OCH2 radical to generate an energy-rich adduct CH3OCH2NO with no barrier involved on the singlet potential energy surface. Subsequently, the most favored dissociation pathway for the formed CH3OCH2NO is a series of H-transfer processes to produce P1 (CH3OCN + H2O), followed by the decomposition of newly formed CH3OCN to generate P2 (CH2O + HCN + H2O). Formation of P3 (CH2O + CH2NOH) by further dissociation of CH3OCH2NO, with a higher barrier needed to overcome, may have a less yield compared to the CH3OCN + H2O production. Moreover, the direct H-abstraction pathway is also identified to produce P4 (ethylene oxide + HNO), and due to a significantly pronounced barrier, it is much less competitive with the association channel. Because the transition states involved in the most favorable pathway lie almost higher than the initial reactants CH3OCH2 + NO in energy, only at high temperatures the reaction between CH3OCH2 and NO is expected to be important. This work can assist in future experimental investigations on the CH3OCH2 + NO reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Eugenol has been used as the bio-based monomer. • A new thermal dual-curing procedure has been implemented. • Thio-Michael and thiol-epoxy were the two click reactions used in the curing process. • The change in the formulation allows for obtaining viscous and gelled intermediate materials. This paper aims to increase sustainability in thermosetting polymeric fields using bio-based monomers and environmentally friendly processing technologies based on dual-curing. Eugenol has been transformed into acrylate epoxy eugenol (AEEU) that can participate in thio-Michael additions and thiol-epoxy reactions. These reactions constitute the first and second steps of the sequential dual-curing process. A basic catalyst has been added to favor the kinetics of the curing process. We have selected three thiols with functionalities 3, 4, and 6, the first is derived from eugenol, and the others are derived from pentaerythritol, all can be obtained from renewable resources. To tailor and improve the intermediate material characteristics in the dual-curing process, we have added the triacrylate of glycerol. By changing its proportion, a liquid or a rubbery solid can be obtained as an intermediate, which allows a significant number of application technologies. Rheology, DSC, and FTIR were used to follow the evolution of both curing steps and to confirm the sequential character of the dual-curing. The thermal characteristics of intermediate and final materials have been evaluated by TGA and DMTA. Tensile tests at break were performed to evaluate the mechanical properties. [ABSTRACT FROM AUTHOR]

The growing utilization of alternative fuels has sparked an interest in understanding the combustion characteristics of oxygenated fuels at low temperature. Cool flame extinction limits provide direct measures of the low-temperature reactivity of fuels and critical information for advanced low-temperature combustion engine design. This paper investigates the effects of fuel and oxygen concentrations on the extinction limits of diffusion cool flames for oxygenated fuels, including dimethyl ether, methyl decanoate, and 1-dodecanol in an atmospheric counterflow burner. The cool flame radical indexes of these oxygenated fuels are developed by isolating the thermal and transport effects from the chemical contribution to diffusion cool flame extinction. The results show that the ranking of low-temperature reactivities of long carbon chain oxygenated fuels, compared with n -alkane, is ether > n- alkane > alcohol > ester for a similar carbon number. Furthermore, due to the critical role of multiple oxygen addition reactions in the low-temperature chemistry, the relationship between the cool flame extinction limit and the oxygen concentration is also explored. The results show that the cool flame extinction limits of the oxygenated fuels are proportional to a n th power of the oxygen concentration, [O 2 ]n, due to the combined effects of multiple oxygen addition reactions and the negative temperature coefficient in low-temperature chemistry. Additionally, the measured n number of 1-dodecanol is found to be larger than 2, which suggests the existence of the third oxygen addition reactions in low-temperature chemistry for large alcohols. [ABSTRACT FROM AUTHOR]

[Display omitted] • A brief review focuses on the recent progress of reversible fluorescent probes in living systems. • The reversible fluorescent probes could repeatedly monitor the dynamic changes of multi-biomolecules in real-time and in situ. • The design principles of the reversible fluorescent probes are summarized. • The review discusses the current progress of the reversible fluorescence probes as well as the perspectives directions. Reversible fluorescent probes have attracted the attention of researchers because of their ability to repeatedly observe the dynamic changes of multi-biomolecules in real-time and in situ. In recent years, fluorescent probes have been wildly used in numerous biological research, among them, the reversible fluorescent probes, resemble based on changes of pH and based on spiral cyclization, have played an important role in the research on biomolecular interactions, which deepened our understanding of the activity of cell life. Although fluorescent probes with reversible processes have been used in real-time to visualize the dynamic changes inside cells for an extended period, however, the lack of a systematic review of this fascinating subject has severely hindered the design and the application of such reversible fluorescent probes for the in-depth understanding of the relationship between the various substances that change during the operation of cells. In this review, we have divided reversible fluorescent probes into six categories for the first time, according to the basic principles of reversible reactions, and focus on the interactions revealed by reversible fluorescent probes between various physiological compounds and small molecules compounds or microenvironmental levels. In order to grasp the topic clearly and intuitively, this paper reviewed the representative example of reversible fluorescent probes in bioimaging also from the chemical perspectives of complex reactions, addition reactions, redox reactions, spiral cyclization, etc. Several representative examples of each reaction were reviewed, all of which demonstrate that reversible fluorescent probes could be powerful tools for visualizing intracellular dynamic changes in real-time. In addition, the existing problems and future challenges in the biological application of reversible fluorescent probes were discussed from multiple angles. This evaluation will aid in creating and enhancing innovative reversible fluorescent probes and serve as a resource for future research into life events. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe N '-(4-(2-butyl-1,3-dioxo-2,3-dihydro-1 H -benzo[ de ] isoquinolin-6-yl)benzylidene)-4-methylbenzenesulfonohydrazide (ENM) that could selectively response to Cu2+, was reported in this paper, which was the first fluorescent probe with sulfonyl hydrazide as the receptor to detect Cu2+. The selectivity, concentration titration, pH titration, time dependence, detection limit and recognition mechanism of ENM for Cu2+ in CH 3 CN/H 2 O solution were investigated. It was shown that ENM exhibited high selectivity, sensitivity and fast response to Cu2+, and the detection limit was as low as 0.27 μmol/L. More importantly, the sensing mechanism was that ENM underwent decomposition reaction with the addition of Cu2+. In addition, ENM could work in a wide pH range. The results of determination of Cu2+ in water samples indicated that ENM had potential practical value in environmental analysis. [Display omitted] • The first fluorescent probe with sulfonyl hydrazide as receptor was designed and synthesized for detection of Cu2+. • This was the first fluorescent probe with sulfonyl hydrazide as receptor for detection of Cu2+. • The probe showed excellent selectivity and sensitivity, indicating its potential applications in practice. [ABSTRACT FROM AUTHOR]

[Display omitted] • A bioderived Schiff base containing polyphosphonate (PVP) was rationally synthesized. • As-developed PVP has a high biomass content of 72% by mass. • The addition of only 0.5 wt% of PVP can lead to exceptional fire retardancy of PLA. • PVP can increase the mechanical strength of PLA as compared to pure PLA. To expand the practical application and realize sustainable development, it is urgent to develop advanced polylactide composites with fire retardancy and mechanically strong properties by utilizing bio-derived additives. Unfortunately, such desired performance portfolio is still unsatisfactory due to unclear mechanism and improper design strategy. In this paper, a novel bio-derived polyphosphonate containing Schiff base (PVP) was prepared by a two-step method of condensation and addition reactions. By incorporating only 0.5 wt% PVP, the LOI value of PLA is increased to 32.5 vol% as well as achieving a UL-94 V-0 rating. Such superior fire retardancy is ascribed to the physical barrier effect of char residue, which arising from the cyclization of Schiff base and catalytic carbonization of polyphosphonate. Due to the crosslinking reaction between PLA and PVP and nucleating effect of PVP in the PLA matrix, the mechanical strength of PLA is increased by 10.2% with addition of 1.0 wt% PVP. This study provides a feasible way for designing bio-derived fire retardants to simultaneously improving the fire retardancy and mechanical strength of PLA, thus is expected to expand the practical application of PLA materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • New radical General-Purpose Reactivity Indicators which are able to predict the reactivity of methyl radical addition reaction. • Use of Mulliken's electronegativity to predict the electrophilic or nucleophilic behavior of a molecule when it reacts with methyl radical. • The spectrum of reactivity of six different molecules susceptible to methyl radical is elucidated. The reactivity of six different unsaturated molecules undergoing methyl radical attack have been studied using thermodynamic and kinetic properties. Regioselectivity has been elucidated using the radical Fukui function and the brand new radical General-Purpose Reactivity Indicators (radical GPRI). We propose a straight-forward methodology that utilizes the electronegativity values of the reagents to assess which of the two radical GPRI equations is the appropriate one to predict the main product of methyl radical addition on each molecule. These results suggest that this new two-parameter chemical reactivity indicator is especially effective in elucidating the regioselectivity of unsaturated reactants under methyl radical attack when the radical Fukui function fails. [ABSTRACT FROM AUTHOR]

Rationale Design of a pair of simple 'switch-on' sensors for selective detection of HSO 3 − along with the verification of reactivity of different unsaturated C=C double bond towards nucleophilic addition reaction. [Display omitted] • Exo-cyclic vs. non-exocyclic C C bonds towards reaction-based sensing. • Highly selective fluorescence "turn-on" sensing of HSO 3 − • Selective naked eye detection of HSO 3 − • Application in paper strip and real water sample. The present report deals with specific colorimetric (naked-eye) and fluorometric sensing of HSO 3 − by a pair of chemodosimetric probes, namely L 1 and L 2. The D-π-A structure-based probes exhibited an outstanding HSO 3 −-dependent response with excellent selectivity and lower detection limit values. The probes were designed to verify the reactivity of exo -cyclic vs. non-exocyclic C C bonds towards reaction-based sensing. It was proven that only activated exo -cyclic C C double bonds were responsible for selective sensing. We also reported the utility of probe-coated paper-strip analysis with L 1 for rapid detection of HSO 3 − in the experimental medium. Also, the ability to detect HSO 3 − in real food sample as well as in river water, lake water, and tap water were also checked by L 1. [ABSTRACT FROM AUTHOR]

The lethal toxicity of cyanide ions has inspired the development of fluorescent probes for their recognition, but fluorescent probes that can selectively bind cyanide ions in aqueous solution have been a challenge. In this paper, the electron-donor/withdrawing groups were introduced to aza-BODIPY fluorophore to discover the optical properties and tune the addition reaction with CN−. The push-pull electron effect of the corresponding substituents in aza-BODIPY makes the spectral shifts, molar extinction coefficients and fluorescence quantum yields remarkably different. The introduction of the electron-withdrawing group (–CF 3) to aza-BODIPY (CF 3 -BDP) resulted in the electron-deficient property of the C N double bond, and the ability of nucleophilic addition of CN− to CF 3 -BDP was enhanced in aqueous solutions. Due to the collapse of the conjugated structure after the addition, the fluorescence of CF 3 -BDP was rapidly quenched to realize the highly sensitive response to CN−. According to DFT calculation, the reaction site of controversial mechanism was verified to the C N band in the pyrrole of aza-BODIPY. Furthermore, CF 3 -BDP was proved to have the ability to detect cyanide in biological system. • Aza-BODIPY dyes with the –OMe/–CF 3 groups at 3,5-sites were prepared. • Aza-BODIPY dyes with electron-donor/withdrawing groups displayed the differences of the addition with CN− in non-aqueous and aqueous solutions. • DFT calculations indicate the effect of substituents on dye's reactivity and identify reactive sites in Path I. • Aza-BODIPY with the –CF 3 groups was highly sensitive and selective to CN− in aqueous solutions. [ABSTRACT FROM AUTHOR]

Despite excellent environmental adaptability and good optical transparency, polysiloxane was poor electron or ion conductors. In this paper, ionized polymethylvinylsiloxane (I-PMVS) had been prepared via coupling anionic ring-opening polymerization of 2, 4, 6, 8-tetravinyl-2, 4, 6, 8-tetramethyl-cyclo-tetrasiloxane with thiolene addition reaction of sodium 2-mercapto-ethanesulfonate (MESNA). The degree of ionization was precisely controlled by adjusting the grafting content of MESNA via clicking chemical reaction. FTIR, 1H NMR, and XRD were used to investigate the composition and structure of I-PMVS. TGA and DSC was used to investigate the thermal properties. The increase of ionization degree reduced the crystallinity of the polymer and bulk cohesion, and increased the T g of I-PMVS and maintained good thermal stability. Meanwhile, the water contact angle (WCA) test showed that the increase of ionization degree improved the hydrophilicity of PMVS and the high degree of ionization made PMVS having excellent water-solubility. The test of tensile properties showed I-PMVS possessed good tensile strength without filler reinforcement. Electrochemical impedance spectra (EIS) indicated I-PMVS possessed a high ionic conductivity (σ), highest to 4.20 × 10−6 S/cm when 100% grafting. Ionization of PMVS should provide a strategy to develop high performance of polyelectrolyte applied in the field of energy storage devices and bionic materials. [Display omitted] • Ionized polysiloxane with adjustable number of ions was obtained via click reaction. • The physical properties were tuned via varying the grafting ratio of ion group. • Mechanical strength and ion conductivity were enhanced via increasing grafting ratio. [ABSTRACT FROM AUTHOR]

• The effect of acidity on the 2-pentyl ketazine was studied by establishing acidity gradient. • The optimum reaction conditions of 5-methyl-3,5-dipropyl-2-pyrazoline catalyzed by chloroaluminate ionic liquid were obtained. • The detailed catalytic mechanism of the reaction was calculated by DFT theory. 5-methyl-3,5-dipropyl-2-pyrazoline is an intermediate for the preparation of new high energy fuels. In this paper, chloroaluminate ionic liquids ([Bmim]Cl-xAlCl 3 , x = 1, 1.2, 1.4, 1.6, 1.8, 2.0) were applied as green catalysts for the synthesis of 5-methyl-3,5-dipropyl-2-pyrazoline through the intramolecular cyclization reaction of 2-pentyl ketazine. The effects of temperature, acidity and dosage of ionic liquids on the cyclization reaction were studied in detail and the highest catalytic performance was under the conditions as 110 °C, [Bmim]Cl-1.6AlCl 3 and 10% of 2-pentyl ketazine. With the theoretical simulations, the possible catalytic mechanism was proposed as the hydrogen-like interaction between Al ([Bmim]+AlCl 4 −) and N1 atoms, which increases the charge of N2 atoms, thereby improving its nucleophilicity and further making it undergo intramolecular addition reaction with methyl. This study will provide guidance for the green preparation of 5-methyl-3,5-dipropyl-2-pyrazoline. [Display omitted] [ABSTRACT FROM AUTHOR]

• Quasi-equilibrium character of the oxidative addition of ArCl to Pd was demonstrated. • Quasi-equilibrated oxidative addition cannot be therefore the RDS. • Low reactivity of ArCl is caused by another reason not related to oxidative addition. The retarded oxidative addition of aryl chlorides to palladium is commonly believed to be the main obstacle for their successful conversion in cross-coupling reactions. However, this point has been fairly challenged in several papers, including those published recently, by providing experimental data obtained under both model and real catalytic conditions. Here, we provide proof of the fast and reversible character of the oxidative addition elementary step with aryl chlorides in the catalytic cycle of the Mizoroki-Heck reaction. The results have been obtained by the original kinetic approach using the differential selectivity of the competing Mizoroki-Heck reaction with two aryl chlorides. The kinetic data obtained in the real phosphine-free catalytic system unambiguously disproved the rate-determining character of the oxidative addition of aryl chloride as the key factor for lowering the catalytic activity when using aryl chlorides instead of aryl iodides and aryl bromides in the Mizoroki-Heck reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

• 1,4-conjugate addition reaction enabled single step synthesis of superhydrophobicity. • An optically transparent superhydrophobic coating is derived from small molecules. • The deposition solution remained stable and active for 200 days in various solvents. • Tailored superhydrophobicity (adhesive force from 24 μN to 204 μN) has been achieved. • Prepared coating remained capable of performing at practically relevant severe settings. In the past, different approaches were adopted to prepare superhydrophobic interfaces for demonstrating various prospective applications, where different polymers or nanomaterials are associated for achieving appropriate hierarchical topography and essential chemistry. The commonly used deposition solutions consisted of polymer or nanomaterials prepared in a specific solvent have poor shelf-life. Moreover, the unavailability of robust and optically transparent superhydrophobic coating following a scalable, rapid and single-step deposition process remained a bottleneck problem for its various prospective and relevant applications at real-world scenarios. Here, a catalyst-free 1,4-conjugate addition reaction between distinct and strategically selected small molecules allowed to prepare an active deposition solution with prolonged (200 days) shelf-life in various and commonly used reaction media. The small molecules derived deposition solution allowed a rapid and scalable synthesis of abrasion tolerant, optically transparent (99.2%) superhydrophobic coating on different relevant fibrous and porous substrates—following either dip-coating or spray coating process. Further, the appropriate choice of small molecules and the concentration of deposition solutions controlled adhesive interaction (from 24 μN to 204 μN) and hydrophobicity (from ∼ 134° to 160°) of the small molecule derived coatings. The entirely small molecules derived bio-inspired coating sustained various physical/chemical abrasive exposures including knife test, repetitive sandpaper abrasion, tensile deformation, adhesive tape peeling, washing, ironing, and prolonged (300 days) UV irradiation, sea water, river water etc. Such interfaces were successfully extended for different practically relevant applications including self-cleaning, oil/water separation, no-loss transfer and mixing of aqueous droplets etc. Moreover, the superior shelf-life of the deposition solution and liberty for selecting different reaction media makes this design exceedingly elegant for industrial scale-up in near future. [ABSTRACT FROM AUTHOR]

This paper explores the low-temperature (low-T) oxidation chemistry of 2,4,4-trimethyl-1-pentene (IC8D4, diisobutylene) by using jet-stirred reactor (JSR) experiments of both IC8D4/dimethyl ether (DME) mixture and pure IC8D4 at near atmospheric pressure and low temperatures. Oxidation species are measured using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS), gas chromatography (GC) and GC combined with mass spectrometry (GC/MS). It is found that the oxidation of pure IC8D4 at atmospheric pressure presents negligible low-T reactivity and negative temperature coefficient (NTC) behavior, and that the oxidation reactivity of IC8D4/DME mixture is lower than that of butene/DME mixtures previously studied. A kinetic model for low-T IC8D4/DME oxidation is developed from recent oxidation models of IC8D4 and DME. Thermodynamic data of IC8D4 and key species in its sub-mechanism are obtained from theoretical calculations in this work, while rate constants of critical reactions are updated from recent theoretical calculation studies in literature. Based on the modeling analysis, four main pathways are found to be responsible for the consumption of IC8D4 at low temperatures. Among them, the first three pathways initiated by H addition, OH addition and H abstraction on allylic carbon sites are similar to those in 1-butene/DME and isobutene/DME oxidation. These three pathways are mainly responsible for promoting or retaining OH formation. The fourth pathway initiated by H abstraction on the alkyl carbon site differs from the other three in that it is only important in IC8D4/DME oxidation while not important in butenes/DME oxidation. This fourth pathway incorporates stepwise O 2 addition and cycloaddition reaction sequences, which can promote and inhibit OH formation, respectively. The increasing contribution of this fourth pathway in IC8D4/DME oxidation reduces its reactivity compared to that of butenes/DME oxidation. [ABSTRACT FROM AUTHOR]

The low-temperature oxidation (LTO) of heavy oil is of great significance for the combustion front stability, which directly influences the efficiency and safety of in-situ combustion (ISC). To provide feasible heating by artificial ignition before the implementation of ISC in the Xinjiang Fengcheng (FC) oilfields, this paper investigates the oxidation behavior of FC extra-heavy oil and its isothermal oxidized oils. Firstly, FC extra-heavy oil was subjected to isothermal oxidation experiments conducted utilizing an oxidation reactor, and the physical properties of the gaseous products and oxidized oils were analyzed. The combustion behavior of the FC extra-heavy oil and oxidized oils was then studied by non-isothermal thermogravimetry and differential scanning calorimetry. Subsequently, the Friedman and Ozawa–Flynn–Wall methods were adopted to perform kinetic analysis. Oxygen consumption was always greater than the production of CO and CO2, so oxygen addition reactions were the main pathway in heavy oil LTO. H/C decreased to 8.31% from 20.94% when the oxidation temperature rose from 50 °C to 150 °C, which deepened the oxidation degree. The density and viscosity of 200 °C to 350 °C oxidized oils increased at a slower rate, which may be related to the LTO heat effect. The change law of temperature interval, peak temperature, and mass loss of the oxidized oils had a good correlation with the static oxidation temperature. Compared with other oxidized oils, the peak heat flow and enthalpy of 350 °C oxidized oil increased significantly with high-temperature combustion, and were 42.4 mW/mg and 17.77 kJ/mol, respectively. The activation energy of 350 °C oxidized oil began to decrease obviously around a conversion rate of 0.4, which indicates that it was beneficial to coke deposition with stronger activity. Finally, we came up with LTO reaction mechanisms and put forward a reasonable preheating temperature for the application of ISC in FC oilfields. [ABSTRACT FROM AUTHOR]

In this paper, the organocatalytic asymmetric 1,4-Michael addition reaction of azadienes and α-thiocyanoindanones was investigated. A series of chiral benzofuran compounds containing thiocyano group and quaternary carbon center were synthesized in moderate yields with good enantioselectivities (up to 90:10 er) and high diastereoselectivities (up to >95:5 dr). This is the first case of 1,4-Michael addition reaction using α-thiocyanoindanones to obtain a series of chiral thiocyano compounds and further broaden the scope of application of azadiene substrates. In addition, a possible reaction mechanism is also described in the article. [ABSTRACT FROM AUTHOR]

In this paper, chemical reaction kinetics at low temperatures on three different methyl crotonate (MC, C 5 H 8 O 2) radicals with O 2 were conducted via quantum chemical methods. The potential energy surfaces (PESs) for these reactions were investigated by M062x/6-311++G(d,p) and CBS-QB3 methods. The related rate coefficients also have been solved by master equations based on Rice-Ramsperger-Kassel-Marcus theory, predicting the competitive relationships over 300 to 1500 K and 0.001 to 100 atm. The calculated results indicated that the rate constants of O 2 addition reaction at ester methylic site were higher than those at allylic sites, which showed that the conjugation effect caused by the C=C double bond has a crucial effect on the reaction process. Formation of initial adducts and intramolecular H-transfer reactions play a great role in the low temperature oxidation of MC. Furthermore, the mechanism of O 2 addition to MC radicals was verified by the previous combustion model. The updated model did a good job to replicate the previous experimental results. This work not only provides the necessary rate constants for the reaction mechanism of MC combustion but also serves as a solid starting point for the further understanding of combustion kinetics of large molecule unsaturated biodiesels. [ABSTRACT FROM AUTHOR]

Herein, lignin was functionalized to obtain quinonoid lignin (QL) and epoxidized lignin (EL), and cellulose was modified to be aminated cellulose (AC). A novel fully bio-based adhesive of QL-AC-EL with multiple cross-linked networks was designed based on Schiff base and addition reaction. Furthermore, the natural wood interface was activated by brushing aqueous solution of 3-aminopropyltriethoxysilane (APTES) to obtain a functional interface with many -NH 2 groups. Finally, the created QL-AC-EL was used as a specific adhesive to glue wood interface with abundant -NH 2 groups. The bonding performance was evaluated that the dry strength of the plywood specimens made from activated wood interface was 3.2 MPa, which increased by 123.8% than that of natural wood interface. It is amazing that the wet strength of plywood by using activated wood interface was 1.73 MPa, whereas wet bonding strength of natural wood was zero. The significantly improvement of the bonding properties should be caused by the covalent crosslinking between adhesive and activated wood interface, which plays an important role in the enhanced water resistance of the interfacial bonding stability. This work provided a new inspiration for the design of bio-based adhesives with excellent performance and water resistance from the interfacial chemical bonding perspective. [Display omitted] • QL-AC-EL was from quinonoid lignin, aminated cellulose, and epoxidized lignin. • QL-AC-EL was proposed based on dual Schiff base and addition reaction. • A fully bio-based adhesive with multiple cross-linked networks was designed. • This work was designed from the interfacial chemical bonding perspective. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superhydrophobic strategies based on condensation and addition reactions. • Oil spill clean-up through selective absorption and active filtration processes. • The scalable manufacturing strategy is low-cost and environment-friendly. oil pollution incidents emerge in endlessly, threatening global ecological security and environmental sustainability. It is a consensus of current scientific research to develop environmentally friendly, sustainable and degradable materials for polluted water body restoration. Cellulose is one of the most attractive candidate materials due to its abundant reserves and all-green degradability. Herein, a technique used to modify lignocellulose fibers via the condensation and addition reactions is reported, and the modified lignocellulose fibers exhibit excellent superhydrophobic and degradation properties. The modification process consists of two main steps: 1) the in situ construction of micro-nano structures on the surface of lignocellulose fibers through the condensation reaction using melamine and formaldehyde; 2) using the addition reaction between the isothiocyanate compound with low surface energy and the amino groups of the melamine resin. The superhydrophobic isothiocyanate/melamine/formaldehyde (IMF) lignocellulose fibers are extremely repellent to water both in atmospheric conditions and underoil. It can separate various oil–water mixtures by absorption (with a high oil absorption capacity of > 1000 wt%) and gravity-driven filtration (with a separation efficiency of > 96%). The embedded superhydrophobicity in the IMF lignocellulose fibers remained unperturbed (with the water contact angle of > 150° and the oil–water separation efficiency of > 97%) even after repeating for 50 cycles. The presented strategy not only indicates a new direction for the comprehensive utilization of abundant lignocellulose fibers, but also proposes a promising way for the development of oil–water remediation technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO 2 -responsive small molecules were modified on cellulose fibers. • Modification performed with esterification followed by aza-Michael addition. • Surface zeta potential demonstrated the CO 2 -responsiveness on the surface. • Anionic dyes and negative nanoparticles can be reversibly captured and released. The remediation of water that polluted by organic dyes and nanoparticles (NPs) remains a great challenge. However, second pollution of solid waste may produce if the adsorbents are not degradable or recyclable. The stimuli-responsive materials were regarded to be able to resolve this problem by reversible adsorption-desorption under stimuli. Here in this work, the surface of cellulose fibers was modified with CO 2 -responsive molecules through a simple esterification followed by an aza-Michael addition reaction. The chemical structure was confirmed with Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), x-ray diffractometer (XRD) and thermal analysis. The gas-responsiveness was demonstrated by monitoring of the pH, conductivity and surface zeta potential. Anionic dyes and negative charged NPs in water can be selectively and reversibly captured by the CO 2 -responsive surface on cellulose fibers, suggesting the inexpensive, readily available and smart cellulose fibers may find great potential in water remediation. [ABSTRACT FROM AUTHOR]