Mechanism Of Chemical Interaction Research Articles

Nonenzymatic Sequestering of Formaldehyde into the Antibiotic Methylene-Bridged Dimer Phaeochromycin F by Streptomyces sp. OUCMDZ-4982 as a Possible Multipronged Chemical Defense Mechanism.

Metabolites with high chemical reactivity serve important roles in chemical defenses of organisms. Formaldehyde, as a simple and highly reactive small molecule, can be produced by microorganisms, plants, and animals. Its toxicity is well known, but information about its other biological functions remains scarce. Here, we report that the natural product SEK34b produced by Streptomyces species can react nonenzymatically with formaldehyde in water to yield the methylene-bridged dimer phaeochromycin F. This process can eliminate the toxic substance formaldehyde produced by Staphylococcus aureus. Furthermore, there is a substantial inhibitory impact of phaeochromycin F on S. aureus. We hypothesize that these constitute an integrated system of defense and attack of Streptomyces species against competitors. Our study indicates that formaldehyde can react with vancomycin and tigecycline under mild conditions to generate the derivatives bearing an imidazolidin-4-one moiety, thereby reducing the antibacterial activity of these antibiotics. These data provide a possible chemical interaction mechanism of bacteria involving the nonenzymatic reactions of formaldehyde with highly reactive natural products.

Co-production of porous N-doped biochar and hydrogen-rich gas production from simultaneous pyrolysis-activation-nitrogen doping of biomass: Synergistic mechanism of KOH and NH3

In this study, a method of simultaneous activation and nitrogen doping during biomass fast pyrolysis for co-production of porous N-doped biochar and H2-rich gas production was proposed. The effect of temperature on chemical interaction mechanism of KOH and NH3 was investigated at 500–800 °C. Results showed that KOH and NH3 had a synergistic effect on pore development and nitrogen doping, and the specific surface area and nitrogen content reached maximum values of 2008.37 m2/g and 5.05 wt%, respectively. It may be due to that NH3 entered pores generating by KOH activation for further activation, and at the same time, excessive NH3 could convert new O-containing groups to N-containing groups for more effective nitrogen doping. What's more, the H2 concentration and yield were up to 56.67 vol% and 517.95 mL/g, respectively. It indicates that the synchronization method of fast pyrolysis-activation-nitrogen doping is a promising approach, which is of great significance for the high-value utilization of biomass.

Reducing carbon dioxide emissions when using methane-hydrogen fuel

AIM. To determine optimal modes for methane decarbonization, as well as to assess CO2 emissions during subsequent combustion of the pyrolysis gas, including together with the natural gas in various ratios.METHODS. The processes of thermochemical conversion of methane into hydrogen and condensed carbon in a reactor with external heating of the walls were considered. The thermal energy required for gas pyrolysis is obtained by burning a mixture of air and part of the pyrolysis gas, which is free from solid carbon particles. When performing numerical studies of pyrolysis processes, a kinetic model of one-dimensional flow of the reacting mixture was used with an external supply of thermal energy through the walls of an axisymmetric channel (tubular reactor).RESULTS. The mechanism of chemical interaction during the thermal decomposition of methane was developed, taking into account the formation of condensed carbon in the temperature range from 1000 to 1200 °C. The main energy indicators and the composition of pyrolysis gas were determined at various values of the pyrolysis temperature and the degree of carbon conversion.CONCLUSION. Carbon dioxide emissions from the combustion of pyrolysis gas, including together with the natural gas, were assessed. When developing pyrolysis technologies and applying them on an industrial scale, it is advisable to use part of the resulting pyrolysis gas with a high hydrogen content to provide thermal energy for the processes of thermal decomposition of the feedstock. According to the calculations, the share of this part reaches ≈ 35% of the total amount of pyrolysis gas. This approach, as opposed to burning the natural gas for this purpose, significantly reduces CO2 emissions. The combustion of the resulting pyrolysis gas, even without removing residual hydrocarbons, is characterized by currently quite acceptable CO2 emission factors of ≈ 7-25 t CO2/TJ.

TEM and zeta potential titration as suitable techniques for investigating the joining of modified ceramic surfaces

Transmission Electron Microscopy (TEM-EDS) and Zeta potential titration of ceramic surfaces allowed researchers to go inside their adhesion mechanism when joined with an adhesive. The case study concerned the plasma Corona treatment to improve the joint strength between SiC surfaces joined with an epoxy adhesive. The formidable mechanical and chemical properties inherent to silicon carbide pose challenges in applying conventional methods like mechanical machining and wet etching for surface texturing. Exploring alternative strategies, plasma Corona treatment which is an Atmospheric Pressure Plasmas (APPs) process emerges as a potential solution. The mechanism of chemical interaction and mechanical interlocking between plasma-treated surfaces and the epoxy adhesive used for the joining was never explored in detail and proven. The presence of layers with different crystallographic natures and chemical compositions was assessed by TEM-EDS: an amorphous silica layer was produced by the corona activation treatment and it created a mechanical anchoring system when penetrated by the adhesive. The zeta potential titration as a function of pH evidenced that untreated SiC had a surface with amphoteric functional groups, while the Corona treatment induced the formation of surface functional groups (OH) with a strong acidic behavior on SiC. The investigated epoxy adhesive exposed a prevalence of basic amino groups. Zeta potential titration curves highlighted the chemical interaction between the treated SiC surfaces and the epoxy adhesive: the large electrostatic attraction between the OH groups of the treated SiC and the amino groups of the epoxy adhesive had a role in the mechanical strength of the joining. TEM and Zeta potential titration can be proposed as suitable techniques to evaluate the effectiveness of the plasma corona discharge system in modifying the surface of SiC and to solidify its standing in comparison to other established surface modification techniques to improve SiC-based joints.

Some Nanocarrier’s Properties and Chemical Interaction Mechanisms with Flavones

Flavones such as 7,8-dihydroxyflavone (tropoflavin), 5,6,7-trihydroxyflavone (baicalein), 3',4',5,6-tetrahydroxyflavone (luteolin), 3,3',4',5,5',7-hexahydroxyflavone (myricetin), 4',5,7-trihydroxyflavone (apigenin), and 5,7-dihydroxyflavone (chrysin) are important both for their presence in natural products and for their pharmacological applications. However, due to their chemical characteristics and their metabolic processes, they have low solubility and low bioavailability. Knowledge about the physicochemical properties of nanocarriers and the possible mechanisms of covalent and non-covalent interaction between nanoparticles (NPs) and drugs is essential for the design of nanocarriers to improve the bioavailability of molecules with pharmacological potential, such as tropoflavin, baicalein, luteolin, myricetin, apigenin, and chrysin. The parameters of characterization of some NPs of these flavones, such as size, polydispersity index (PDI), zeta potential, encapsulation efficiency (EE), and % release/time, utilized in biomedical applications and the covalent and non-covalent interactions existing between the polymeric NPs and the drug were analyzed. Similarly, the presence of functional groups in the functionalized carbon nanotubes (CNTs), as well as the effect of pH on the % adsorption of flavonoids on functionalized multi-walled carbon nanotubes (MWCNT-COOH), were analyzed. Non-covalent interaction mechanisms between polymeric NPs and flavones, and covalent interaction mechanisms that could exist between the NPs and the amino and hydroxyl functional groups, are proposed.

The underlying mechanisms of PM2.5 and O3 synergistic pollution in East China: Photochemical and heterogeneous interactions

The rapid development of Chinese cities is accompanied by air pollution. Although the implementation of air pollution control strategies in recent years has alleviated PM2.5 pollution, O3 pollution and the synergistic pollution of PM2.5 and O3 have become more serious. To understand the underlying chemical interaction mechanisms between PM2.5 and O3, we applied the modified Weather Research and Forecasting model with Chemistry (WRF-Chem) to study the effects of aerosol-photolysis feedback and heterogeneous reactions on the two pollutants and revealed the contribution of different mechanisms in different seasons and regions in Yangtze River Delta (YRD) in eastern China. We found that, through the aerosol-photolysis feedback, PM2.5 decreased the surface photolysis rates JNO2 and JO1D, resulting in a decrease in O3 concentration in the VOC-sensitive area and a slight increase in the NOx-sensitive area. The heterogeneous reactions reduced O3 concentration in the YRD in spring, autumn and winter by consuming HxOy. While in summer, the heterogeneous absorption of NOx decreased O3 in the NOx-sensitive areas and increased O3 in the VOC-sensitive areas. Heterogeneous reactions also promoted the secondary formation of fine sulfate and nitrate aerosols, especially in winter. Through the combined effect of two chemical processes, PM2.5 can lead to a decrease in O3 concentration of −3.3 ppb (−7.6 %), −2.2 ppb (−4.0 %), −2.9 ppb (−6.3 %), and − 5.9 ppb (−18.7 %), in spring, summer, autumn and winter in YRD. Therefore, if the PM2.5 concentration decreases, the weakening effect of PM2.5 on the ozone concentration will be reduced, resulting in the aggravation of ozone pollution. This study is important for understanding the synergistic pollution mechanism and provides a scientific basis for the coordinated control of urban air pollution.

Modeling heterochromatin dynamics in S. pombe across diverse timescales.

From bread yeast to human cancer cells, histone regulation underpins the epigenetics of almost all eukaryotic genes. While it is possible to experimentally isolate the behavior of single elements of histone regulation, using that data to generate a full mechanistic understanding of regulation is nontrivial. To isolate the machinery involved, we have chosen to model the elements of gene silencing in S. pombe on several spatial and temporal scales. These models were based on many single molecule experiments done in vivo on the dynamics of evolutionarily conserved parts of the regulation machinery, such as Swi6, Clr4, and the SHREC complex. Using the Lattice Microbes software package, we synthesized these independent experimental results to model an interacting network of gene regulation. We began by modeling the chemical behavior of the individual regulators: we used single molecule experimental results where possible, and generated several plausible mechanisms of chemical action for chemical behaviors that were not precisely known. Different mechanisms on the chemical level suggested different timescales and spatial behaviors for small scale histone modification to affect larger scale transcription. We were able to compare these theoretical timescales to timescales in S. pombe adaptive epigenetic silencing experiments, allowing us to identify the likeliest chemical interaction mechanisms. With these, we were able to construct models on the timescale of gene regulation which captured the spatial and temporal dynamics of the chemical mechanisms while remaining computationally efficient. Because we can now efficiently model chemically accurate epigenetic mechanisms, we can now model epigenetic decision making, allowing us to probe how eukaryotic cells might thrive even under novel stresses or subvert apoptotic triggers.

Effects of different chloride salts on granite residual soil: properties and water–soil chemical interaction mechanisms

Effects of different chloride salts on granite residual soil: properties and water–soil chemical interaction mechanisms

Environmental characteristics of thermal utilization of waste with external and internal supply of thermal energy

THE PURPOSE. Identification of optimal regimes for autothermal and allothermic methods of gasification of plant biomass in terms of energy parameters of generator gases, as well as determination of environmental indicators during subsequent combustion of generator gases to obtain thermal energy.METHODS. When modeling gasification processes, a nonstoichiometric model was used, based on the assumption that a chemically reacting multicomponent mixture is in a state of thermodynamic and chemical equilibrium, which corresponds to the minimum value of the isobaric-isothermal potential. When modeling the combustion of generator gas in a mixture with air, a kinetic model of a perfectly mixed flow reactor was used and the detailed mechanism of chemical interaction for the C-H-O-N-S reacting system was taken into account. The calorific value of generator gas obtained by steam gasification and external supply of thermal energy is significantly higher than the calorific value of gas obtained by internal supply of thermal energy. However, the values of the energy potential and thermochemical efficiency are very close for both types of gasification.RESULTS. For plant biomass with a given averaged elemental composition, gasification conditions are determined that increase the degree of conversion of initial materials into generator gas. In particular, for the autothermal gasification method, the maximum calculated values of the energy potential of dry ash-free generator gas and thermochemical efficiency were obtained at an excess air coefficient α ≈ 0.32. For the allothermic gasification method, the maximum calculated values of the energy potential of the generator gas and the thermochemical efficiency correspond to the gasification temperature range T ≈ 1050 -1100 K and the mass fraction of the supplied steam gH2O ≈ 0.217. To ensure these conditions, it will be necessary to supply thermal energy through combustion of ≈ 37 wt. % generator gas. Generator gas produced by the allothermic method has higher energy performance, and the negative impact on the environment during its subsequent combustion is characterized by lower specific CO and CO2 emissions in terms of a ton of reference fuel.

Surface Regulation through Dipolar Molecule Boosting the Efficiency of Mixed 2D/3D Perovskite Solar Cell to 24%

AbstractMixed 2D/3D perovskite solar cells (PSCs) show promising performances in efficiency and long‐term stability. The functional groups terminated on a large organic molecule used to construct 2D capping layer play a key role in the chemical interaction mechanism and thus influence the device performance. In this study, 4‐(trifluoromethyl) benzamidine hydrochloride (TFPhFACl) is adopted to construct 2D capping layer atop 3D perovskite. It is found that there are two mechanisms synergistically contributing to the increase of efficiency: 1) The TFPhFA+ cations form a dipole layer promoting the interfacial charge transport. 2) The suppressed nonradiative recombination of perovskite through the coordination of TFPhFA+ cations with Pb–I octahedron, as well as the recrystallization of 3D perovskite induced by Cl‐ ions. As a result, the PSC delivers an efficiency of 24.0% with improved open‐circuit voltage (VOC) of 1.16 V, short‐circuit current density (JSC) of 25.42 mA cm‐2, and fill factor of 81.26%. The device shows no decrease in efficiency after 1500 h stored in the air indicating the good stability. The utilization of TFPhFACl not only provides a facile way to optimize the interfacial problems, but also gives a new perspective for rational design of large spacer molecule for constructing efficient 2D/3D PSCs.

Chemical aspects of the application of basalt in cement composites

• Overview of main applications of basalt in cement composites is presented. • Chemical interactions of basalt with corrosive environments are described. • Chemical reactivity of various forms of basalt in cementitious matrices is assessed. • Gaps in the current knowledge are identified. • Suggestions for future research are formulated. Basalt belongs to materials widely used in engineering. Basalt-based products are common in civil engineering, automotive, or boat building, but they can be found, e.g., also in wind turbine blades or sporting goods. This paper is focused on the chemical aspects of the application of basalt in cement composites, a seemingly narrow area that was not surveyed in sufficient detail to date. At first, an overview of the main applications of basalt in cement composites is presented. The effects of active fillers, coarse aggregates, and various types of reinforcement on functional properties are analyzed using a set of characteristic examples. Then, the chemical reactivity of various forms of basalt in cementitious matrices is assessed. Mechanisms of chemical interactions of basalt with corrosive environments are described on a general level to provide a guide for such assessment. Consequently, the interactions of basalt in powdered or aggregate form and basalt reinforcement with the cement matrix are specified from a chemical point of view. Finally, suggestions for future research inspired by the revealed gaps in the current knowledge are formulated.

Dynamics of adhesive systems development in dental practice

BACKGROUND: Тhe article presents a review of adhesive systems in terms of their component chemical composition. Seven generations of adhesive systems have been studied. The first generation of adhesive systems emerged in the 1970s. The result of the action was the bond reaction of the adhesive with calcium enamel and dentin. Glycerophosphoric acid dimethacrylate was used. The use of methacrylates in adhesive systems was widespread because polymers with high biological indifference to biological objects are formed when they are polymerized in combination with acrylic resin. The second generation used a lubricated layer to obtain higher adhesion rates. Chloro-substituted phosphate esters of various monomers were used as active groups. The main compound mechanism remained the ionic binding of calcium dentine by chlorophosphate groups. The third generation used a lubricated layer to attach the composite to the dentin in the same way as the second generation. In the chemical composition, aluminosilicates, aluminitrates, hydroxyethylmethacrylate (HEMA), 4-methacryloxyethyltrimethyl anhydride (4-META), and other substances were most often used as active groups. The fourth generation is a multicomponent system that provides a three- and four-step application technique. These systems contain three to four components (conditioner, primer, and adhesive). The technique of their use includes three stages, namely, etching with 37% orthophosphoric acid, priming, and bonding. Adhesive systems of the fifth generation are two-component systems that provide a two-step technique of application. First, acid (etching) is applied to the tooth tissue, and second, the adhesive itself. Adhesive systems of the sixth and seventh generations are one-component self-etching since the adhesive contains acid. From a chemical point of view, these adhesive systems are a mixture of phosphoric esters and adhesive substances. Therefore, analyzing the adhesive composition of seven generations in such way, the mechanism of chemical interaction of adhesive components with hydroxyapatite and dentin has not significantly changed; however, the number of hydrophobic fragments has increased, which significantly increases dentin contact.

Low Cost, Recyclable and Magnetic Moringa Oleifera Leaves for Chromium(VI) Removal From Water

Chromium(VI) a heavy metal by nature, is one of the most toxic metals in the environment. We recently reported functionalized Moringa Oleifera (FMO) leaves as a low cost and efficient adsorbent for the removal of Cr(VI) and bacterial from water, as a continuation, we report the incorporation of magnetic nanoparticles (Fe3O4) with previously studied FMO for Cr(VI) removal from aqueous solution. Iron oxide due to its magnetic properties has been shown to assist in the recovery of its adsorbents. In this study, in-situ co-precipitation synthesis of iron nanoparticles onto FMO was employed. During chemical precipitation, the iron precipitate tends to cover the FMO thus forming some outer-shell coating of magnetite on the surface of FMO. The Fe3O4/FMO was characterized using XRD, FTIR, SEM, BET, TGA and Zeta potential. FTIR results showed a new developed intense peak at 685.6 cm−1 for Fe-O stretching, indicating successful incorporation of Fe3O4 nanoparticles onto FMO. Powder XRD was further use to confirm the formation and further indicated that the structure of FMO was still intact even after the Fe3O4 incorporation. The adsorption conditions such as pH, dosage, time and concentration were optimized to 2, 0.15 g, 25 min and 20 mg/L, respectively. The adsorbent was selective toward Cr(VI) since 99% was removed in the presence of interfering ions (20–100 mg/L). The adsorbent (Fe3O4/FMO) could also be reused up to 4 times with a percentage Cr(VI) removal of >80% in the 4th cycle. Adsorption kinetics studies obeyed pseudo second-order model, suggesting a chemical interaction mechanism (chemisorption) between Fe3O4/FMO and Cr(VI). Therefore, the adsorbent has shown that it can be used for selective removal of Cr(VI) from wastewater and potentially other heavy metals as well.

Adsorption behaviour of simulant radionuclide cations and anions in metakaolin-based geopolymer

Geopolymers are a class of alkaline-activated materials that have been considered as promising materials for radioactive waste disposal. Currently, metakaolin-based geopolymers (MK-GPs) are attracting interest for the immobilisation of radionuclides in contaminated water from the Fukushima Daiichi Nuclear Power Station. However, the associated chemical interaction mechanisms and the theoretical prediction of the adsorption behaviour of MK-GP in response to cationic radionuclides have not been thoroughly studied or fully understood. In addition, there is a lack of studies on the adsorption capacity of MK-GP for anionic radionuclides. In this study, two types of metakaolin-based (Metastar501 and Sobueclay) geopolymers were synthesised at a K2O:SiO2:H2O ratio of 1:1:13. The binding capacity and interaction mechanism of MK-GP with Cs+, Sr2+, Co2+, I-, IO3-, SeO32-, and SeO42- were evaluated based on the zeta potential, radionuclide binding, and alkali leaching. The results showed that MK-GP does not have the ability to incorporate anionic radionuclides irrespective of the metakaolin source used, but both types of geopolymers have a high capacity to immobilise cationic radionuclides. The uptake of Cs+ was observed as a one-to-one exchange between Cs+ and K+ whereas both one–two and one–one ion exchanges are possible in the case of Sr2+ and Co2+ with K+. The formation of cobalt blue (CoAl2O4) also contributed to the binding of Co2+. Thermodynamic modelling was conducted according to the ion exchange mechanism which predicts the binding of Cs+ and Sr2+ at low concentrations.

Fluorine adsorption on floating iron nanoparticles confined to gigaporous structure of large adsorbent water spheres

Effective defluoridation of artesian well water can be performed with iron nanoparticles confined to expanded reticulated polymer network of polyvinyl alcohol (PVA) containing a high quantity of water. For this purpose, large (3433 ± 63 μm) adsorbent water spheres, meaning spheres containing Fe2O3 (15.8 wt%)-PVA (8.2 wt%)-H2O (76.0 wt%), were manufactured (sol–gel process) and characterized (TG/DTA, XRD, MÖSSBAUER, SEM/EDS, BET, FTIR, and XPS). In the resulting spongy water spheres, gigapores (140,000 nm) were filled with loosely agglomerated and floating naked nanoparticles (<20 nm) of octahedral [Fe2O2(H2O)8]2+ and/or [Fe2O3(H2O)6]0 complexes without prejudice to the chemical and mechanical (35.0 ± 0.4 kPa) stability of the nanostructured adsorbent. The built-in mesoporous and gigaporous structure provided good pore connectivity, which significantly reduced the adsorption rate limitation imposed by boundary-layer and intraparticle diffusion effects as well as it has enhanced the adsorptive capacity (from 77.9 to 204.9 mgF/g) of the referred adsorbent water spheres. XPS proved the chemical interaction mechanism in F–Fe–PVA–H2O system. Fluoride chemisorption occurs on PVA (marginally; (-CH2CHF-)n, (-CH2CF2-)n, and (-CF2CF2-)n) and Fe (predominantly; octahedral Fe2F5.7H2O complex) particles. Adsorbent water spheres can defluorinate natural waters in multiple adsorption cycles in fixed bed columns after fluorine desorption with NH4OH.

Synergistic and competitive effect of H2O on CO2 adsorption capture: Mechanism explanations based on molecular dynamic simulation

The presence of water vapor in post-combustion gas streams is a challenging technical issue that limits the utilization of CO2 adsorbents. Understanding the physical and chemical interaction mechanisms between adsorbents and adsorbates is the key to effectively deal with the competitive adsorption of CO2 and H2O. In this paper, a thermodynamic molecular pump (TMP) is proposed to resolve the contradictions between the promotion and impedance of CO2 adsorption by H2O. Specifically, the TMP model was proposed for quantitative analyses on a molecular scale for the first time. The equilibrium adsorption isotherms and adsorption enthalpies for CO2 and H2O at 298–388 K were obtained by grand canonical Monte Carlo (GCMC) simulations, while the adsorption entropies were obtained by density functional theory (DFT). Furthermore, the Gibbs free adsorption energy was then obtained by considering the effects of temperature and adsorption sites. The TMP-based analysis showed that the Gibbs free adsorption energy of H2O was a significant factor that influenced the CO2 adsorption result due to its contribution to the total driving energy. For CuBTC (BTC: benzene-1,3,5-tricarboxylate), the CO2 adsorption entropy provided a greater driving force to adsorb CO2 preferentially at 348–388 K. For zeolite AFI, the adsorption enthalpy was always the largest driving force. The results show that the adsorption temperature had a strong influence on zeolites. At 320–360 K, the zeolites showed better CO2/H2O adsorption selectivity than metal–organic frameworks (MOFs) due to their sensitivity to the thermal driving forces, as predicted by the TMP model. This is especially significant for the potential application of zeolites in temperature swing cycles driven by low- and medium-grade energy. The TMP model can provide guidance for screening CO2 adsorbents in the presence of H2O.

Behavior of hydrates in cement paste reacted with silicate-based impregnant

In order to improve the durability of concrete structures, silicate-based impregnant have been used, but the chemical interaction mechanism is not clear. Silicate-based impregnant react with calcium hydroxide, which is formed during the process of cement hydration, and form compounds similar to a calcium silicate hydrate (C–S–H). This paper performs reaction experiments by Ca/Si ratio, and solid state nuclear magnetic resonance (NMR) and X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy are conducted for observing chemical changes of cement paste with silicate-based impregnants. Based on the results of XRD, reduction of monosulfate phase was observed as well as the formation of C–S–H (tobermorite-like phase). 29Si and 27Al NMR spectra also correspond with the XRD results. Further, possibility of both Al/Si substitution and formation of a structure close to C-(A)-S-H (C–S–H containing Al) were observed. Therefore, silicate-based impregnant formed not only new C–S–H reacting with calcium hydroxide, but also influenced other hydrates.

Control of a Detonation Wave in a Channel with Obstacles Using Preliminary Gas Mixture Preparation

Using the detailed kinetic mechanism of chemical interaction, the effect of preliminary preparation of the stoichiometric hydrogen-air mixture (dissociation of a part of molecular hydrogen and oxygen on atomic gases) on the detonation wave characteristics is investigated numerically with the aim to control detonation combustion in plane channels with obstacles. It is found that the above-mentioned partial initial dissociation can be used to prevent quenching of detonation in channels with both a single obstacle and multiple barriers. It is revealed that the mixture, obtained as a result of preparation, differs from the initial hydrogen-air mixture by the qualitatively different type of detonation re-initiation after interaction with obstacles.

Investigation on the interaction mechanism between nanocellulose and adhesion RH

A complex of resorcinol and hexamethylenetetramine (RH) was utilized to modify nanocellulose (NCC) using in‐suit solution method, where NCC was extracted from eucalyptus pulp paper with ultrasonic oxidation steps. The modified NCC was then put into vulcanized condition to simulate vulcanization process of rubber; the product was called vulcanized RH‐NCC model compound. In this paper, we study whether vulcanized conditions have influence on the interaction between RH and NCC by comparing changes of RH‐NCC model compounds before and after vulcanization. The analysis of thermogravimetry (TG), X‐Ray Diffraction (XRD), and water contact angle shows that addition of RH can improve some properties of NCC, which demonstrates well interaction between them. Fourier transform infrared (FTIR) test shows that there are no big changes before vulcanization; however, after simulated vulcanization, characteristic peaks of compound have changed a lot, illustrating that some chemical reactions have occurred. Further research on data from fitting peaks of hydrogen bonds and X‐ray photoelectron spectroscopy (XPS) analysis found that before vulcanization, mechanism between RH and NCC was mainly physical hydrogen interaction, and chemical interaction mechanism was also put forward after vulcanization.

Detonation Combustion Control Using Preliminary Preparation of the Gas Mixture

The effect of preliminary preparation of a stoichiometric hydrogen–air mixture (decomposition of a part of molecular hydrogen and molecular oxygen into atomic gases) on the characteristics of a propagating detonation wave is numerically studied using a detailed kinetic mechanism of chemical interaction. It is revealed that this preliminary dissociation leads to a significant reduction in the transverse size of the detonation cell with a slight increase in the propagation velocity of the self-sustained wave, which allows using this preparation to prevent detonation damping in channels with both a single obstacle and multiple barriers.