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Hydrocarbons with higher blending octane number compared to octane number may have a higher antiknock effect for multi components fuel in comparison with the effect predicted from octane number as a single component. In this study, the antiknock effect of isooctane, 4-octyne and 2,3-dimethyl-2-butene for multi components fuels were discussed based on the analysis of reaction products in a flow reactor. As a result, it was suggested that low temperature oxidation reactions of n-heptane promote oxidation reaction of these hydrocarbons. In addition, it was suggested that reaction products from hydrocarbons with high blending octane number such as 4-octyne and 2,3-dimethyl-2-butene inhibit chain reactions by consuming radicals produced from the low temperature oxidation reaction of n-heptane. [ABSTRACT FROM AUTHOR]

Biogenic volatile organic compounds (bVOCs), synthesised by plants, are important mediators of ecological interactions that can also undergo a series of reactions in the atmosphere. Ground-level ozone is a secondary pollutant generated through sunlight-driven reactions between nitrogen oxides (NOx) and VOCs. Its levels have increased since the industrial revolution and reactions involving ozone drive many chemical processes in the troposphere. While ozone precursors often originate in urban areas, winds may carry these hundreds of kilometres, causing ozone formation to also occur in less populated rural regions. Under elevated ozone conditions, ozonolysis of bVOCs can result in quantitative and qualitative changes in the gas phase, reducing the concentrations of certain bVOCs and resulting in the formation of other compounds. Such changes can result in disruption of bVOC-mediated behavioural or ecological interactions. Through a series of gas-phase experiments using Gas Chromatography Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS), we investigated the products and their yields from the ozonolysis of a range of ubiquitous bVOCs, which were selected because of their importance in mediating ecological interactions such as pollinator and natural enemy attraction and plant-to-plant communication, namely: (E)-β-ocimene, isomers of α and β-farnesene, α-terpinene and 6-methyl-5-hepten-2-one. New products from the ozonolysis of these compounds were identified, and the formation of these compounds is consistent with terpene-ozone oxidation mechanisms. We present the degradation mechanism of our model bVOCs and identify their reaction products. We discuss the potential ecological implications of the degradation of each bVOC and of the formation of reaction products. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The degradation of ribavirin(RBV) by ferrate(Fe(Ⅵ)) was systematically investigated for the first time by experiment and degradation process fitting. The results indicated that the reaction between Fe(Ⅵ) and RBV is pH dependent and followed second order kinetics. The species-specific rate constants of the Fe(Ⅵ) species(HFeO 4 -) were higher than FeO 4 2- species when react with RBV. Fe(VI) made significant contribution to the removal of RBV. Liquid chromatography-triple quadrupole mass spectrometry(LC-TQ-MS) was used to determine the intermediate of RBV which degradated by Fe(Ⅵ), in order to infer its main degradation pathway. This study used Dual Descriptor and Fukui function to calculate the active sites of RBV and its intermediates during the degradation of RBV by Fe(Ⅵ), then verified their accuracy with actual reaction sites deduced based on LC-TQ-MS data. The results showed that Dual Descriptor prediction was more accurate than Fukui function in the process of RBV degradation by Fe(Ⅵ). Some common anions in natural waters, such as SO 4 2-, NO 3 -, Cl- and CO 3 2- had no effect on the removal of RBV by Fe(Ⅵ). 50 mg/L HA reduced the 120 min removal efficiency of RBV by 15.07%. Both toxicity analysis by ECOSAR software and E. coli toxicity experiments showed that Fe(VI) achieves toxicity reduction of RBV. This study indicated that Fe(Ⅵ) can effectively remove RBV from water and using Dual Descriptor to analyze the active sites of intermediates in the RBV degradation pathway can enhance the rationality of predicting the reaction pathway. [Display omitted] [ABSTRACT FROM AUTHOR]

To enhance the efficiency and durability of the gas turbine and aircraft components, thermal barrier coatings (TBCs) are the most considerable protection techniques available. The present work is mainly concentrating on improving the high-temperature corrosion characteristics of uncoated and plasma-spray coated alloy A-286 under Na2SO4-5%NaCl-7.5%NaVO3 deposit at 900°C. By using plasma spray process NiCrAlY and YSZ (bond coat-NiCrAlY and top coat-YSZ) thermal barrier coating was deposited on the alloy A-286. Coating characterization such as roughness was analysed on the coating surface and coating thickness and hardness analysis were performed on the coating region at the cross section. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to study the phases and coating microstructure before and after being subjected to corrosion. The rate of corrosion was derived by thermo-gravimetric analysis. Using the elemental mapping technique and EDS compositional analysis, the scale thickness and corrosion attack were identified. During the corrosion experiment, sputtering and spallation of oxide were noticed on the uncoated specimen. The oxide layer failure was not found in both the coated specimens. The results indicated that YSZ coating exhibits a better corrosion resistance than NiCrAlY. The reaction products such as monoclinic ZrO2 and YVO4 were found in the corroded YSZ coating. There was no significant failure, but degradation was found on the coating due to molten salt. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aromatic hydrocarbons represent a large fraction of anthropogenic volatile organic compounds and significantly contribute to tropospheric ozone and secondary organic aerosol (SOA) formation. Toluene photooxidation experiments were carried out in an oxidation flow reactor (OFR). We identified and quantified the gaseous and particulate reaction products at 280, 285 and 295 K using a proton-transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) coupled to a CHemical Analysis of aeRosol ONline (CHARON) inlet. The reaction products accounted for both ring-retaining compounds such as cresols, benzaldehyde, nitrophenols, nitrotoluene, bicyclic intermediate compounds, as well as ring-scission products such as dicarbonyls, cyclic anhydrides, small aldehydes and acids. The chemical system exhibited a volatility distribution mostly in the semi-volatile (SVOCs – semi-volatile organic compounds) regime. The saturation concentration (Ci*) values of the identified compounds were mapped onto the two-dimensional volatility basis set (2D-VBS). Temperature decrease caused a shift of Ci* towards lower values while there was no clear relationship between Ci* and oxidation state. The CHARON PTR-ToF-MS instrument identified and quantified approximately 70–80 % of the total organic mass measured by an aerosol mass spectrometer (AMS). The experiments were reproduced by simulating SOA formation with the SSH-aerosol box model. A semi-detailed mechanism for toluene gaseous oxidation was developed. It is based on the MCM and GECKO-A deterministic mechanisms modified following the literature in particular to update cresols and ring-scission chemistry. The new mechanism improved secondary species representation with an increment of the major identified species (+35 % in number). Light compounds formation (i.e. m/z < 100) is enhanced and accumulation of heavy compounds (i.e. m/z ≥ 100) is reduced, especially in the gas phase. Additional tests on (i) partitioning processes such as condensation into aqueous phase, (ii) interactions of organic compounds between themselves and with inorganics and (iii) wall losses were also performed. When all these processes were taken into account the simulated SOA mass concentration showed a much better agreement with the experimental results. Finally, an irreversible partitioning pathway for methylglyoxal was introduced and considerably improved the model results, opening a way to further developments of partitioning in models. Our results underline that the volatility itself is not sufficient to explain the partitioning between gas and particle phase: the organic and the aqueous phases need to be taken into account as well as interactions between compounds in the particle phase. [ABSTRACT FROM AUTHOR]

Copyright of Journal Of Sichuan University (Natural Sciences Division) / Sichuan Daxue Xuebao-Ziran Kexueban is the property of Editorial Department of Journal of Sichuan University Natural Science Edition and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have investigated the potential use of commercial limestone powder (LP) of 10 to 40%.wt to replace slag in a new ternary alkaline system (BFS-GP-LP) activated by both (Na2SiO3 and NaOH). Ten mixtures of AAPs and AAMs are prepared; the aim is to understand the influence of precursor on fresh property, reaction kinetics and products, mechanical and microstructural properties; then it's compared with those of OPC. The findings indicate that the setting times of AAPs are prolonged when increasing LP content to by 40% (870, 1042 min); however, they are slower compared to OPC (320, 425 min). Despite the incorporation of LP improves spreading values to 184 mm, AAMs registered less workability than OPC. Using 20% GP provides a better CS (68 MPa) and FS (10 MPa); using LP harms strengths, but its use by 10%.wt improves the early age FS of MSG from 3.67 to 5.25 MPa and provides a higher CS (62.90 MPa) than OPC (60.90 MPa). The formation of reaction products is prolonged to 162 h when using 40% LP. Characterization testing identified that the main reaction product of AAMs is C-S-H gel. Microstructural analysis indicates that the samples contain LP have a heterogeneous and less compact structure. [ABSTRACT FROM AUTHOR]

A pulse gas-detonation device (PGDD) is applied to investigate the process of initiation and detonation in C2H2+ O2 acetylene–oxygen mixtures, including those with a low oxygen content near the upper detonation concentration limit, at initial atmospheric pressure. Cell sizes, detonation velocities, and pressures in detonation products are measured in a range of from zero to unity. The detonation product composition is calculated. Upper detonation limits in the PGDD barrels with diameters of 14, 26, 46, and 104 mm are determined. The volume of booster charges required to initiate detonation in the limiting modes are revealed. As for the hydrogen energy industry, the methane acetylene hydrogen + nanosized detonation carbon technological chain is considered, and the characteristics of the PGDD as a hydrogen generator are estimated. [ABSTRACT FROM AUTHOR]

This study aims to improve the high-temperature resistance and water resistance of magnesium oxysulfate cement (MOSC) through introducing silica fume (SF). The residual strength of MOSC after exposure to high temperatures of 200 °C, 400 °C, 600 °C and 800 °C was tested. The softening coefficient of MOSC after immersion in water for 28 days was used to evaluate the water resistance. The results revealed that SF enhanced the high-temperature resistance of MOSC at temperatures exceeding 200 °C. For SF-MOSC system, prolonged exposure to high temperature of 400 °C could further promote the transformation of partial MgO to M-S-H gel. This phenomenon extremely increased the residual compressive strength of SF-MOSC. Although the residual strength of MOSC and SF-MOSC decreased sharply at 600 °C, the SF-MOSC still displayed a better high-temperature resistance performance. At 800 °C, the MgO in SF-MOSC could have a solid-solid reaction with silicon source to generate forsterite with high melting point. Additionally, SF exhibited favorable filling effects in MOSC and could restrict the conversion of MgO to Mg(OH) 2 , which also promoted the crystallization of 5Mg(OH) 2 ·MgSO 4 ·7H 2 O (5·1·7 phase). The decreased Mg(OH) 2 after immersion in water and further generation of partial 5·1·7 phase contributed to the enhancement of MOSC's water resistance in this study. • The influence mechanism of SF on the high-temperature resistance and water resistance of MOSC was revealed. • SF could inhibit the conversion of MgO to Mg(OH) 2 and thus promote the generation of 5·1·7 phase. • Exposure to high temperature of 400 °C for a long time could facilitate the generation of M-S-H gel in SF-MOSC. • The MgO had a reaction with silicon source in SF-MOSC to form forsterite when exposed to high temperature of 800 °C. [ABSTRACT FROM AUTHOR]

This study is undertaken to explore the relationship between the reaction products and the drying shrinkage of alkali-activated slag (AAS) with the varying hydroxide dosage. AAS pastes were firstly produced with either Al(OH)3 or Mg(OH)2 to investigate the effects of hydroxide on the composition of reaction products and the drying shrinkage of AAS. Secondly, the main reaction products formed in AAS pastes, viz. C4AH13, M4AH10, C-S-H, C-A-S-H and C-M-S-H, were synthesized individually. Synthetic products were then taken to cast the respective paste sample to examine the performance against the drying exposure. The results show that adding Mg(OH)2 indeed improved the shrinkage resistance of AAS. This is primarily connected to the increased crystalline phases, namely the hydrotalcite-like phases and the unreacted Mg(OH)2. Whereas adding Al(OH)3 did not relieve the drying shrinkage of AAS as the interlayer spacing of C-A-S-H was enlarged, which in turn allowed for more shrinkage. Further, the investigation of individual synthetic products illustrates that their drying shrinkage scales satisfied the following order: C4AH13

Antibiotics are resistant compounds with low biodegradability and cannot be effectively eliminated by conventional wastewater treatment methods. The aim of this study was to evaluate the photocatalytic removal of erythromycin using magnetic nanoparticles (Fe-doped TiO2@Fe3O4) from aqueous solutions. Fe-doped TiO2@Fe3O4 nanoparticles were synthesized by sol-gel method, and scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, value-stream mapping, Brunauer-Emmett-Teller, and diffuse reflectance spectroscopy analyses were used to determine the properties of the synthesized nanoparticles. Effect of various variables including pH (3-9), initial concentration of erythromycin (25-75 mg/L), and concentration of nanoparticles (200-600 mg/L) at different times (15-60 min) was examined in the photocatalytic removal of erythromycin. The results of this study showed that the highest removal efficiency of erythromycin and the highest reaction rate constant were obtained using a fixed beam with a UVC lamp 15 W at pH = 5, the initial concentration of 25 mg/L, and the dose of nanoparticles 600 mg/L at the reaction time of 60 min. Due to the high removal efficiency of erythromycin by Fe-doped TiO2@Fe3O4 process in the presence of UVC light and stability of nanoparticles after 5 reuse, the application of this process in water and wastewater treatment processes is recommended. [ABSTRACT FROM AUTHOR]

Constitution and distribution of phases and interphase reactions are crucial for properties of composites. So far, the problem of MoS 2 agglomeration remains unsolved in Cu/MoS 2 composites, and interfacial structures and reaction products between MoS 2 and Cu have not been fully considered. Herein, Cu-coated MoS 2 powders prepared via electroless plating were sintered at different temperatures into Cu/MoS 2 composites. Cu does not react with MoS 2 in the composites sintered at 600 ℃ and 650 ℃, leading to their desirable tribological properties under dry sliding. Reactions between Cu and MoS 2 occur in the composites sintered at 700 ℃ and 800 ℃, and the resultant products include Cu 2 S, Cu 1.8 Mo 6 S 8 and Cu 1.83 Mo 3 S 4 phases, resulting in a better wear resistance under oil lubrication and mechanical properties. [ABSTRACT FROM AUTHOR]

Alkali-activated Fe-rich non-ferrous metallurgical slag (AA-NFS), within the FeO x -SiO 2 -Al 2 O 3 -CaO-MgO system, were tested in 2 wt% sulfuric acid for 6 months. Corrosion depth and rate were measured non-destructively by micro X-ray computed tomography. Both intact and corroded areas were characterized by XRD, FTIR, SEM-EDX and NMR. AA-NFS with higher Ca/Si showed a higher resistance to sulfuric acid. The presence of Mg negatively affected the resistance, whereas higher Al concentrations slightly enhanced the resistance in the investigated chemical composition range. The corrosion degree is closely related to the NFS reaction extent in AA-NFS, and this corrosion process is diffusion-controlled. Leaching of the elements (Al, Ca, Mg, Fe and Na) leaves behind mostly silica-rich gels, causing the failure of the framework structure after long-term exposure. The leached Ca2+ reacted with SO 4 2− in acid solution and formed expansive sulfate products, which possibly clog pores and offer an additional protective barrier for AA-NFS against sulfuric acid. [Display omitted] • H 2 SO 4 resistance of Fe-rich alkali-activated material affected by slag chemistry. • The increasing Al/Si and Ca/Si improve the reaction degree. • Increased reaction degree leads to higher resistance. • The corroded layer's integrity influence resistance. • The attack is diffusion-controlled and forms gypsum and silica gel. [ABSTRACT FROM AUTHOR]

The proper control of the rheological performance of silicate-based alkali-activated slag (AAS) mixtures is problematic, as the conventional superplasticizers become less effective in alkaline media. Nevertheless, several methods have been proposed to improve the workability of silicate-activated AAS, such as by extending the mixing time, and replacing sodium silicate with sodium carbonate activators. However, the underlying fluidizing mechanism is not yet well understood in the literature, which is crucial knowledge to achieve proper rheology control of silicate-activated AAS. In this study, the effects of mixing conditions and activator anionic species on the rheology of silicate-activated AAS concrete have been assessed. The reaction products, particle size and interparticle interactions, as well as the reaction kinetics in AAS, have been further investigated to understand the distinct fluidizing mechanisms. By using a longer mixing time, it was found that the solid particles formed at early ages are broken down into smaller particles, accompanied by a slight increase in the amount of reaction products to improve the fluidity. With the sodium carbonate substitution, the calcium ions dissolved from slag particles are entrapped into calcium carbonate precipitates to slow down the accumulation of C-(A)-S-H phases, leading to a better dynamic flow. However, the interparticle interactions are intensified due to the formation of larger particles and the declined dispersing effect induced by silicate activators. [ABSTRACT FROM AUTHOR]

Lithium slag is a silica-aluminum solid waste, and its leaching activity in alkali solution determines its application prospect in alkali-activated cementitious materials. In this study, based on the leaching characteristics of lithium slag in sodium hydroxide solution, combined with microscopic testing methods, investigates the leaching activity of Si, Al, and Ca in lithium slag under different alkali concentrations, leaching times, and leaching temperatures. The interrelationships between the physicochemical properties, leaching behavior, and reaction activity of lithium slag were revealed, and a leaching model for lithium slag was established to elucidate the leaching kinetics process. The results indicate that compared to leaching time, alkali concentration and leaching temperature have a more significant impact on the leaching of Si and Al in lithium slag. The leached Si and Al in lithium slag mainly participate in the formation of N-A-S-H and C-A-S-H reaction products. The optimal leaching scheme was obtained through a predictive model for Si and Al leaching from lithium slag. The leaching process of lithium slag in sodium hydroxide solution is controlled by the diffusion behavior of the product layer, with activation energies for leaching Si and Al being 23.9562 kJ/mol and 24.3278 kJ/mol, respectively. [Display omitted] • In lithium slag, Si and Al are more readily leached out than Ca. • Mutual reactions between ions generate (N-A-S-H, C-A-S-H) and Ca(OH) 2. • Effect of single factor on dissolution rate: concentration > temperature > time. • This model can be used for predicting the leaching of Si and Al in lithium slag. • The leaching process is controlled by the diffusive behaviour of the product layer. [ABSTRACT FROM AUTHOR]

The use of glycol ethers as solvents and chemical intermediates has increased markedly in recent years. Once released into the atmosphere, they can undergo degradation processes mainly by reactions with the atmospheric oxidants that can have significant effects on the environment. In this work, the kinetic and products study of reactions of 2-isopropoxyethanol (2-iPE, (CH 3) 2 CHOCH 2 CH 2 OH) with OH and NO 3 radicals and Cl atoms have been performed using FTIR (Fourier Transform Infrared Spectroscopy) and GC-MS (Gas Chromatography/Mass Spectrometry) as detection techniques. The rate coefficients obtained were (units cm3 molecule−1 s−1): (2.18 ± 0.15) × 10−10, (1.88 ± 0.10) × 10−11 and (3.16 ± 0.45) × 10−15 for Cl, OH· and NO 3 · reactions, respectively. The kinetic results obtained have been included in comparison tables of the general reactivity of hydroxy ethers to extract conclusions of the atmospheric behaviour of this type of compounds. The main products detected and quantified have been isopropyl formate, formaldehyde, 2-hydroxyethyl acetate and, in the case of NO 3 · reactions, nitrated compounds. A reaction mechanism has been proposed according to the reaction products obtained. The calculated lifetimes have been determined and Global Warming Potential (GWP) and Photochemical Ozone Creation Potential (POCP E) have been estimated, concluding, first, that the reaction with OH radicals is the main pathway of degradation of this and others glycol ethers in the atmosphere, second, that these compounds have GWP negligible and third, that they could have influence on ozone generation at local and regional level. [Display omitted] • First kinetic data for the reaction of 2-iPE with Cl atoms and NO 3 radicals. • High reactivity of hydroxyethers due to the presence of alcohol and ether groups. • Mechanism proposed with the formation of carbonylic and multifunctional products. • Short atmospheric lifetime with OH radicals, what implies a local impact. • Importance of the products formed and its POCP. [ABSTRACT FROM AUTHOR]

Abstract Myricetin, with its pyrogallol B‐ring, is evidently instable in DMEM (Dulbecco's modified Eagle's) medium at 37°C. However, the underlying mechanism of this instability is not clear yet. Herein, the reaction products of myricetin in DMEM were investigated via an in situ UPLC–MS–MS analysis. Myricetin was mixed with prewarmed DMEM in an autosampler screw top vial for UPLC. Immediately, a 50‐µl sample was automatically injected every 50 min. Myricetin was highly stable in dimethyl sulfoxide (DMSO) when kept at 37°C for 2 weeks. Myricetin was very unstable in DMEM at 37°C and largely converted to new products A (m/z = 635.07) and B (m/z = 633.05) within 1 min. Another new product, C (m/z = 469.04), was detected after the fourth injection (150 min). Myricetin was much more stable in DMEM at 4°C as compared to 37°C. There was a minor conversion of myricetin to the new product A (m/z = 635.07) within 1.0 min, but it subsequently increased until the sixth injection (250 min), and disappeared after the fifteenth injection (700 min). In summary, myricetin first formed a dimer A (m/z = 635.07) and then was oxidized to B (m/z = 633.05), which was finally degraded to C (m/z = 469.04) in DMEM. This process was significantly affected by the temperature, and low temperature is helpful to detect the unstable products.

• The catalytic oxidation efficiency of Hg0 at low temperatures in multi-pollutant environments was investigated. • The oxidation efficiency of Hg0 over 5%CuO/TiO 2 was obviously higher than that over 7%CeO 2 /TiO 2. • In the atmosphere of N 2 +Hg0+SO 2 , SO 2 competed with Hg° for the active sites and thus inhibited the oxidation efficiency of Hg0. • 5%CuO/TiO 2 had better sulfur resistance than 7%CeO 2 /TiO 2 mainly due to strong interaction of Cu and Ti. Background :This study aimed to establish novel photothermal catalysts suitable for the reaction at temperatures of 100-200 ℃ to develop an innovative Hg0 and NO simultaneous removal technology in a lower temperature environment. To further explore the stability and sulfur resistance of 7%CeO 2 /TiO 2 and 5%CuO/TiO 2 , the oxidation efficiency and reaction mechanisms of Hg0 were investigated in multi-pollutant environments at low temperatures. Methods: TiO 2 , CeO 2 /TiO 2 , and CuO/TiO 2 used to oxidize Hg0 at low temperatures were prepared by the sol-gel method, which were localized to glass beads for each test. A self-designed photothermal catalytic reaction system consisted of a mercury generator, a mixing chamber, a catalytical reactor, and an m on-line mercury measuring instrument. Significant Findings: The oxidation efficiencies of Hg0 for different reaction temperatures were ordered as η 100℃ >η 150℃ >η 200℃ in the atmosphere of N 2 +Hg0. In the atmosphere of N 2 +Hg0+NO, low concentration of NO (<300 ppm) exhibited inhibitive effect to Hg0 oxidation, while high concentration of NO (>300 ppm) enhanced Hg0 oxidation. In the atmosphere of N 2 +Hg0+SO 2 , SO 2 could occupy the active sites for Hg0 oxidation and inhibited the oxidation of Hg0. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Journal of Faculty of Pharmacy of Ankara University / Ankara Üniversitesi Eczacilik Fakültesi Dergisi is the property of Ankara University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Considering that waste incineration fly ash is the main carrier of dioxins and can migrate over long distances in the atmosphere, it is of great significance to study the photochemical transformation behavior of dioxins on the surface of fly ash. In this work, 2-chlorodibenzo-p-dioxin (2-CDD) was selected to conduct a systematic photochemical study. The influence of various factors on the photodegradation of 2-CDD were first explored, and the results showed that small particle size of fly ash, low concentration of 2-CDD and appropriate level of humidity were more conducive to photodegradation, with the highest degradation percentage reaching 76%–84%. The components of fly ash (Zn (Ⅱ), Al (Ⅲ), Cu (Ⅱ) and SiO2) also had a certain promoting effect on the degradation of 2-CDD, which increases the degradation efficiency by 10%–20%, because they could act as effective photocatalysts to produce free radicals for reaction. With a higher total light exposure intensity, natural light environments led to a more complete degradation of 2-CDD than laboratory Xe lamp irradiation (90% degradation Vs. 79% degradation). Based on chemical probe and radical quenching experiment, hydroxyl radical also contributed to 2-CDD photodegradation on fly ash. A total of 16 intermediate products were detected by mass spectrometry analysis, and four initial reaction pathways of 2-CDD were speculated in the process, including dechlorination, ether bond cleavage, hydroxyl substitution, and hydroxyl addition. According to the results of density functional theory calculation, the reaction channels of ether bond cleavage and •OH attack were determined. The toxicity assessment software tool (TEST) was used to assess the toxicity and bioconcentration coefficient of reaction products, and it was found that the overall toxicity of the photodegradation products was reduced. This study would provide new insights into the environmental fate of dioxins during long-range atmospheric migration process. [Display omitted] • 2-CDD was degraded by direct photolysis and HO• oxidation on irradiated fly ash. • Zn 2+ , Al 3+ , Cu 2+ and SiO 2 had a promoting effect on photodegradation of 2-CDD. • Degradation of 2-CDD was observed under sunlight and lab Xe lamp irradiation. • Initial dechlorination, bond cleavage, substitution and addition products formed. [ABSTRACT FROM AUTHOR]

Acid treatment is one of the main methods of stimulating the near wellbore area of the wells opening the carbonate reservoirs. Despite the extensive experience of using this technology both in Russia and abroad, as well as a significant number of studies, the success rate is hardly ever estimated at over 30%. One of the reasons for the low success rate is neglect to the changes in the physical properties of fluids during injection, interaction with the rock and the properties of the reaction products in the wellbore and the near wellbore area during the acid treatment planning. This paper discusses the main chemical reactions occurring during the interaction of hydrochloric acid with limestones and dolomites. The quantities of the substances resulting from a chemical reaction between 15% aqueous solution of acid and the carbonates have been determined. The properties (phase state, solubility, dependences of viscosity and density on pressure and temperature) of water, carbon dioxide, nitrogen, 15% aqueous solution of acid, solutions of calcium and magnesium chloride salts in the range of possible pressures and temperatures during the acid treatment were evaluated. Due to the diversity of additives used in acid solutions, the paper proves the necessity of conducting laboratory experiments to evaluate their properties under the conditions expected during the acid stimulation. Based on laboratory studies, the reaction time of 15% solution of hydrochloric acid with calcium carbonate was estimated. The impact of the chemical diverter used for primary treatments at the Badra oilfield (Iraq) on the properties of the acid solution and the reaction time was determined. The changes in the solution viscosity depending on the acid temperature and concentration were determined. The results provided in the work were used for the purposes of forecasting and evaluating the efficiency of acid treatment performed on the wells of the Badra oilfield.

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Allyl alcohol (AA) is the simplest unsaturated alcohol. Ozonolysis is one of the key removal processes for AA in the atmosphere. However, a recent theoretical study suggests that the ozonolysis of AA cannot feasibly occur in atmospheric conditions because of the high barrier (~96 kcal/mol) involved in the primary ozonide (POZ) decomposition. In this work, the ozonolysis mechanism of AA was reinvestigated theoretically. The computed barrier for POZ decomposition is only ~20 kcal/mol. Therefore, the AA ozonolysis can take place in the atmosphere, consistent with the experimental conclusions. Moreover, two new Criegee intermediates (syn‐ and anti‐AA‐CI) were found to be produced in this reaction. The wave function analyses indicate that there exists an intermolecular hydrogen bond in syn‐AA‐CI, which significantly affects its unimolecular decomposition and reactions with H2O. Compared with the normal reactions of anti‐CI‐AA, the stabilized syn‐AA‐CI has two distinct isomerization channels: (i) addition of OH group to the reactive sites of CI forming an ethylene oxide (HOOCH2OCH2) and (ii) double H‐transfer producing HOOCH2CHO. Meanwhile, the addition of H2O in syn‐AA‐CI also exhibits two different pathways. One is the unique addition‐coupled double H‐transfer, and the other is the addition‐coupled single H‐transfer, both leading to the formation of CH2(OH)CH(OH)OOH. [ABSTRACT FROM AUTHOR]

Crystalline ASR products were extracted from concrete exposed to natural environment and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman microscopy, X-ray diffraction and dynamic water vapor sorption. All extracted samples display similar compositions and Raman spectra. They sorb a limited amount of water vapor between 70 and 97% relative humidity (RH), amounting to 13–25 mass-%. Three different phases are identified, with d-spacings at low diffraction angles of 13.4, 12.3 and 10.8 Å. However, none of the phases show a change in d-spacing going from dry (~50% RH) to moist (~100% RH) conditions, indicating that no extra water is sorbed in the interlayer. This clearly indicates that swelling of crystalline ASR products is not responsible for stress generation and concrete cracking.

This research aims at gaining a further understanding of the impact of accelerating admixtures on the reactivity of supplementary cementitious materials (SCMs), which are widely used as a clinker replacement in blended cements. This was done on synthetic glasses with controlled composition and structure that mimic two types of real SCMs (slag and calcium-rich fly ash). The effects of DEIPA, TIPA, NaSCN and Na2S2O3 on the glass dissolution, hydration kinetics and reaction products were investigated. The obtained results concluded that the pH of the NaOH solution and the composition of the synthetic glass play a key role on the effect of the admixtures. In 0.1 M NaOH (pH = 13.0), all the studied admixtures inhibited the dissolution of slag-like glasses while they enhanced the dissolution of Ca-rich fly ash-like glasses, being Na2S2O3 the admixture that led to the highest increase of the dissolution rate of the Ca-rich fly ash-type glasses. In 1 M NaOH solutions (pH = 13.8), only the alkali admixtures (NaSCN and Na2S2O3) enhanced the degree of reaction of both glasses. In slag-type glasses pastes mixed with 1 M NaOH, the addition of 2% Na2S2O3 induced the highest increase of their reactivity as inferred by the total heat release and the amount of bound water. This is related to the formation of a high amount of S(II)-AFm, in addition to C-A-S-H, that would increase the aluminium undersaturation of the pore solution and consequently the further dissolution of the glass.

The presence of dimethylacetamide (DMAA) in the composition of electrolytes of a sodium-ion battery destroys the passive film on electrodes and results in a number of reactions not connected with the electrochemical process that must be considered in developing such batteries. Introducing DMAA into the composition of a battery electrolyte greatly improves the conductivity of the polymeric membrane that separates the cathode and anode spaces. However, it is established that in the presence of sodium metal, anhydrous DMAA undergoes Claisen-like self-condensation with subsequent reactions. IR spectroscopy is used to explain the causes of the electrochemical instability of sodium perchlorate solutions in mixed solvents containing DMAA. [ABSTRACT FROM AUTHOR]

Structures were established for the products of the reactions of 2,2-di(4-nitrophenyl)-1-chloroethene and 2,2-di(4-nitrophenyl)-1,1-dichloroethene with sodium nitrite and the ratio of these products was found using chemical balance, high-performance liquid chromatography, and IR spectroscopy data. The reaction of 2,2-di-(4-dinitrophenyl)-1-chloroethene with nitrite ion in dimethylformamide gives 50% 4,4'-dinitrobenzophenone, 30% 4,4'-dinitrobenzophenone oxime, and 20% 4,4'-dinitrobenzanilide. The products of the reaction of 2,2-di(4-nitrophenyl)-1,1-dichloroethene with NaNO2 in DMF gives 95–97% 4,4'-dinitrobenzophenone and 2.5–3.0% 4,4'-dinitrobenzophenone oxime. [ABSTRACT FROM AUTHOR]

Understanding the role of curing conditions on the microstructure and phase chemistry of alkali-activated materials (AAMs) is essential for the evaluation of the long-term performance as well as the optimization of the processing methods for achieving more durable AAMs-based concretes. However, this information cannot be obtained with the common material characterization techniques as they often deliver limited information on the chemical domains and proportions of reaction products. This paper presents the use of PhAse Recognition and Characterization (PARC) software to overcome this obstacle for the first time. A single precursor (ground granulated blast-furnace slag (GBFS)) and a binary precursor (50% GBFS–50% fly ash) alkali-activated paste are investigated. The pastes are prepared and then cured in sealed and unsealed conditions for up to one year. The development of the microstructure and phase chemistry are investigated with PARC, and the obtained results are compared with independent bulk analytical techniques X-ray Powder Fluorescence and X-ray Powder Diffraction. PARC allowed the determination of the type of reaction products and GBFS and FA’s spatial distribution and degree of reaction at different curing ages and conditions. The results showed that the pastes react at different rates with the dominant reaction products of Mg-rich gel around GBFS particles, i.e., Ca-Mg-Na-Al-Si, and with Ca-Na-Al-Si gel, in the bulk paste. The microstructure evolution was significantly affected in the unsealed curing conditions due to the Na+ loss. The effect of the curing conditions was more pronounced in the binary system.

In the course of an investigation on using calcium stearate (CaSt) to improve performance of the alkali-activated slag (AAS) cement, the objective of the present work is to discovery its role in the AAS system. Special interest is devoted to understand the influence of CaSt on the reaction process, reaction products and microstructural features of the AAS cement. To achieve this, isothermal calorimetry, impedance characteristics, infrared spectroscopy, X-ray diffraction, thermogravimetry, nitrogen sorption, mercury intrusion porosimetry and scanning electron microscopy were carried out. According to results obtained, the CaSt has three important effects on the AAS cement. Firstly, it inhibited slag reaction with the activator through decreasing activity of alkalis, whereas the amount of C-(A)-S-H gels in the system depended on the usage of CaSt, because the CaSt could have chemical reactions with the alkali-solution and form similar reaction products. Secondly, there is less sodium and more calcium in reaction products of the CaSt added mix, which improve their stability and uniformity. Finally, microstructure characteristics (e.g. pore size distribution, pore connectivity) are optimised and defects are reduced significantly, when CaSt is added in the AAS mix. [ABSTRACT FROM AUTHOR]

Polyfluorinated dibenzo- p -dioxins (PFDDs) are dioxin compounds that have been detected in industrial fluoroaromatic chemicals and can cause adverse effects to organisms. In this work, the photochemical behaviors of PFDDs congeners on silica was systematically investigated. The pseudo-first-order rate constants (k , h−1) of surface photolysis changed with the substitution number and position of fluorine atoms, and the tetra-fluorinated PFDDs tended to degrade more efficiently. Octafluorinated dibenzo- p -dioxin (OFDD) was selected as a representative to explore the reaction mechanisms. Product analysis showed that OFDD was decomposed into hydroxylated PFDDs (OH-PFDDs) and hydroxylated polyfluorinated diphenyl ethers (OH-PFDEs) via hydroxyl substitution and (OH radical mediated or direct) C–O bond cleavage. Coupling elimination reaction was also observed, resulting in the formation of three-membered and four-membered ring compounds. According to the extracted peak areas in mass spectra and the energy barrier in potential energy surface, direct homolysis of C–O bond occurs as the dominant reaction pathway. This work could provide some new insights into the environmental fate of dioxin compounds. Image 1 • Photochemical behaviors of PFDDs congeners on silica surface were examined. • Photoreactivity of PFDDs depends on fluorine atoms and their positions. • OH-PFDDs and OH-PFDEs were formed via hydroxyl substitution and C–O bond cleavage. • Coupling elimination reaction produced 3-membered and 4-membered ring compounds. [ABSTRACT FROM AUTHOR]

Abstract—By differential thermal analysis and X-ray phase analysis, the reducing properties of special-purpose coke (Reksil) used in the electrothermal production of silicon are compared with those of other solid reducing agents. On the basis of the derivatograms, the kinetic characteristics of the redox processes are calculated. [ABSTRACT FROM AUTHOR]

Abstract Reactions between calcium magnesium aluminium silicates (CMAS) and Gd 2 Zr 2 O 7 or 2ZrO 2 ∙Y 2 O 3 (ss) are investigated within a temperature range of 1200–1300 °C and for durations of 1 h–100 h. The evolution of CMAS penetration depth in Gd 2 Zr 2 O 7 and 2ZrO 2 ∙Y 2 O 3 (ss) pellets varies considerably depending on the interaction time. A quantitative analysis of the nature and composition of phases observed in stationary conditions (powder/powder interaction) is performed by SEM-FEG coupled with WDS analyses using micro-agglomerated nanoparticles of Gd 2 Zr 2 O 7 and 2ZrO 2 ∙Y 2 O 3. Faster kinetics of the gadolinium-based system are illustrated through an analysis of the morphology of the reaction area and of the resulting CMAS tightness of reaction products. The compositions and quantities of reaction products observed at equilibrium are very similar for the two systems, but transient states are significantly different. [ABSTRACT FROM AUTHOR]