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In this study, the temperature and volume fraction distributions of liquid silicon nanoparticles in the aerosol flow in gas-phase synthesis were retrieved using tomographic reconstruction of emission and extinction spectra in the 230–700 nm range. Measurements were done in an optically accessible microwave-plasma flow reactor fed with a SiH4/H2/Ar gas mixture. Optical emission and extinction spectra in the visible spectral range were captured along a line perpendicular to the flow direction covering the entire cross-section of the Si particle stream. Particle temperature and volume fraction distributions were determined and the preferred location of the silicon particles in a 1-mm thick zone at the circumference of the cylindric flow was revealed. The combined recording of line-resolved emission/extinction spectra is a promising method for spatially-resolved detection of nanoparticles in combustion or gas-phase synthesis.

The self-assembly of thermoresponsive amphiphilic diblock copolymer PMMA21-b-PNIPAM283 is studied in different water/methanol mixtures. It consists of a short hydrophobic poly(methyl methacrylate) block and a long thermoreponsive poly(N-isopropylacrylamide) block. Adding methanol as a cosolvent causes the PNIPAM block, which is soluble in both pure water and pure methanol, to collapse due to so-called co-nonsolvency effect. Meanwhile, the addition of methanol reduces the incompatibility of the PMMA block with water. By means of turbidimetry and differential scanning calorimetry, the solvent-composition-dependent phase diagram is constructed. Dynamic light scattering and synchrotron radiation based small-angle X-ray scattering (SAXS) provide structural information at 20 °C in dependence on the solvent composition. In water-rich solvent mixtures, self-assembled spherical core-shell micelles are formed. The internal structure of the micelles is adjusted by the solvent compositions in two ways: methanol softens the PMMA micellar core, while it causes the shrinkage of the PNIPAM micellar shell. In methanol-rich solvent mixtures beyond the miscibility gap, the copolymers are molecularly dissolved chains. They are collapsed near the coexistence line, while they become random coils as the methanol content increases. We propose that the internal morphology of the micelles and the conformation of the dissolved chains depend strongly on the solvent composition, as a consequence of the superposed co-nonsolvency effect of PNIPAM and the overall enhanced solvation of PMMA when adding m ethanol.

We demonstrate how the evaporation properties of gas-borne nanoscale materials, here liquid silicon and germanium nanoparticles, can be obtained through a novel combination of in situ time-resolved...

Solutions of iron(III) nitrate nonahydrate (INN) in ethanol and 1-propanol are interesting starting materials for producing iron oxide nanoparticles by spray flame synthesis. For the design of these processes, it is important to have information on solid-liquid equilibria (SLE) in these solutions. As corresponding data were not available in the literature, we have studied the SLE of solutions of INN in ethanol and 1-propanol experimentally at temperatures between 288.15 and 308.15 K at 101.3 kPa. Unexpected phenomena occur in these solutions: one would expect an increasing amount of precipitate upon increasing the concentration of the salt INN, but the reverse behavior is observed for a wide range of states. This is caused by chemical reactions in the solutions: not INN, but iron(III) hydroxide (IH) precipitates from the solution, leading also to a strong acidity of the mixture. These chemical effects are taken into account in a physico-chemical model that was developed for describing the SLE in the studied systems. In that model, the physical non-ideality is described with the extended Pitzer model.

The present work provides thermophysical data on binary mixtures of titanium(IV) isopropoxide (TTIP) and 2-propanol (iPOH), which are important precursor solutions in spray flame synthesis of nanoparticles. The specific density, viscosity, thermal conductivity, and molar isobaric heat capacity were measured at 101.3 kPa and temperatures ranging from 293.15 to 333.15 K. The vapor–liquid equilibrium (VLE) was measured at pressures ranging from 20 to 80 kPa. Furthermore, self-diffusion coefficients of pure iPOH were measured at 101.3 kPa and temperatures ranging from 293.15 to 333.15 K. A qualitative study using 1H NMR spectroscopy provides evidence for a cross-association between TTIP and iPOH in the mixture. Correlations for all studied thermophysical properties are provided. The results establish a rational basis for the design of spray flame synthesis processes.

With increasing nitrogen purity, PSA plants require an over-proportional air demand with the consequence that high-purity PSA systems engender a distinct interest in energy-saving measures. This paper presents process intensification strategies with the focus on a reduced energy consumption. Therefore, the influence of PSA configuration and cycle organisation on process performance was investigated. Results are presented at two product purity levels (10 ppm/1000 ppm O2) and two operating temperatures (25 °C/45 °C) in a lab-scale twin bed PSA (2 × 2 L). It is shown that dedicated strategies are available to intensify the PSA process; however, their effects are dependent on ambient conditions and product purity levels.

Gas-phase iron compounds strongly affect the flame structure already at very low concentrations, which implies the control of combustion efficiency, pollution formation, and materials synthesis in flames. The impact of iron pentacarbonyl on low-pressure premixed flames was investigated experimentally and numerically for a broad range of equivalence ratios. The burner was operated in top-to-bottom orientation, causing a strong effect of buoyancy on the flow field, a configuration, also known as buoyancy-opposed flame. The application of ultra-sensitive broadband intracavity laser absorption diagnostics enabled path-integrated measurements of gas-phase FeO in the particle-laden flow. Spatially-resolved temperature distributions were measured via OH laser-induced fluorescence. The measurements were complemented by detailed simulations of the down-firing flame to determine the (one-dimensional) flow field on the centerline of the burner. The experimental findings were the basis for extension of existing reaction schemes for iron-doped flames and a new skeletal scheme was proposed. Measured temperatures and normalized FeO concentrations were used to validate both the detailed and the skeletal scheme. The results of the optimization and reduction procedure helped to improve the understanding of the structure of the iron-doped flame and the role of iron-cluster formation in the interaction mechanisms which cause the flame inhibition or promotion by iron-compounds.

Late-evaporating liquid fuel wall-films are considered a major source of soot in spark-ignition direct-injection (SIDI) engines. In this study, a direct-injection model experiment was developed to visualize soot formation in the vicinity of evaporating fuel films. Isooctane is injected by a multi-hole injector into the optically accessible part of a constant-flow facility at atmospheric pressure. Some of the liquid fuel impinges on the quartz-glass windows and forms fuel films. After spark ignition, a turbulent flame front propagates through the chamber, and subsequently sooting combustion is detected near the fuel films. Overlapping laser light sheets at 532 and 1064 nm excite laser-induced fluorescence (LIF) of polycyclic aromatic hydrocarbons (PAH) -potential soot precursors- and laser-induced incandescence (LII) of soot, respectively. The 532 nm light sheet has low fluence to avoid the excitation of LII. The LII and LIF signals are detected simultaneously and spectrally separated on two cameras. In complementary line-of-sight imaging, the fuel spray, chemiluminescence, and soot incandescence are captured with a high-speed color camera. In separate experiments, toluene is added to the isooctane as a fluorescent tracer and excited by pulsed 266 nm flood illumination. From images of the LIF signal, the fuel-films’ thickness and mass evolutions are evaluated. The films survive the entire combustion event. PAH LIF is found in close vicinity of the evaporating fuel films. Soot is found spatially separated from, but adjacent to the PAH, both with high spatial intermittency. Average images additionally indicate that soot is formed with a much higher spatial intermittency than PAH. Images from the color camera show soot incandescence earlier and in a similar region compared to soot LII. Chemiluminescence downstream of the soot-forming region is thought to indicate the subsequent oxidation of fuel, soot, and PAH.

We report state-resolved absorption cross-section measurement and oscillator-strength evaluation of the gas-phase iron oxide (FeO) orange system near 611 nm. Intracavity absorption spectroscopy (ICAS) with a homemade broadband dye laser was applied for time-resolved measurements of absorption spectra of shock-activated mixtures of iron pentacarbonyl and carbon dioxide (diluted in argon), generating gas-phase FeO. The measurements were performed with a time resolution of 170 µs in the spectral range of 16,316–16,353 cm−1 that includes a large number of FeO absorption lines. Across the 8-cm diameter of the shock tube, ICAS leads to an effective absorption path length of 260 m. Absorption cross-section values of 0.5 × 10–18–4 × 10–18 cm2 were determined for temperatures around 2200 K and pressures of ∼1.3 bar. Pressure- and temperature-independent oscillator strengths for individual ro-vibronic transitions within the 611-nm band of FeO orange system are reported for the first time. These data are generally applicable for quantitative absorption measurements of flame studies of iron chemistry, where FeO plays a key role as intermediate species.

Ethanol is known to be prone to pre-ignition in internal combustion engines under high-load conditions and its ignition shows large deviations from ideal, spatially, and temporally-homogeneous ignition in shock tubes at moderate temperatures (800–950 K). In this context, the ignition of stoichiometric ethanol/O2 mixtures with various levels of inert gas dilution was investigated in a high-pressure shock tube at ≅20 bar between 800 and 1250 K. Ignition delay times were determined from spatially integral detection of chemiluminescence emission. Additionally, high-repetition-rate color imaging enabled the differentiation of the luminescence in time, space, and spectral range between various ignition modes. In the low-temperature range (800–860 K), different inhomogeneous ignition modes were identified. The addition of small amounts of helium into the undiluted fuel/air mixture was found to be efficient to mitigate pre-ignition, attributed to a variation in heat transfer and thus suppression of the build-up of local temperature inhomogeneities. The experiments in case of spatially homogeneous ignition show very good agreement with the predictions based on three detailed kinetics mechanisms (Zhang et al., CNF 190 (2018) 74, Frassoldati et al., CNF 159 (2012) 2295, and Zhou et al. CNF 197 (2018) 423), inhomogeneities, however, resulted in a shortening of the ignition delay times up to a factor of 2.6.

Tetramethylsilane is a precursor often used for the production of flame-synthesized silica nanoparticles or coatings. This study investigates the chemical reaction mechanism of tetramethylsilane in a series of H2/O2/Ar low-pressure (p = 30 mbar) flames from fuel-lean to slightly fuel-rich flame conditions (φ=0.8, 1.0 and 1.2). Mole fraction profiles are obtained by molecular-beam mass spectrometry. The experimental data are compared to simulations using a recently published reaction mechanism. The present study reveals the influence of the flame composition on the depletion of the precursor TMS, the formation of its main carbon-containing products (e.g. CO2 and CO) and the main silicon-containing intermediates (e.g. Si(CH3)3(CH2)OO), Si(OH)4, SiO2, Si4O10H4) appearing along the routes of particle formation. TEM images of synthesized particles reveal that the nanoparticles obtained from the gas-phase synthesis are spheres with a low degree of agglomeration. The particle size distribution appears to be dependent on the equivalence ratio of the synthesis flames and the changes can tentatively be traced to different particle formation pathways. The data set provided in this work can serve a basis for improvements to the reaction mechanisms of the Si/C/H/O system that are urgently needed to improve particle synthesis processes.

Journal of materials chemistry / A 9(8), 4831-4840 (2021). doi:10.1039/D0TA11096E, Published by Royal Soceity of Chemistry, London [u.a.]

Shock-tube and flow-reactor experiments were used to study the thermal decomposition of diethyl carbonate (C2H5OC(O)OC2H5; DEC). The formation of CO2, C2H4, and C2H5OH was measured with gas chromatography/mass spectrometry (GC/MS) and high-repetition-rate time-of-flight mass spectrometry (HRR-TOF-MS) behind reflected shock waves. The same products were also detected by GC/MS in flow reactor experiments. All experiments combined span a temperature range of 663–1203 K at pressures between 1.0 and 2.0 bar. Time-resolved species concentration profiles from HRR-TOF-MS and product compositions from GC/MS measurements were simulated applying a detailed reaction mechanism for DEC combustion. A master-equation analysis was conducted based on computed energies from G4 calculations. Quantum chemical calculations confirm that DEC primarily decomposes by six-center elimination, C2H5OC(O)OC2H5 → C2H4 + C2H5OC(O)OH (1a) , followed by rapid decomposition of the alkoxy acid, C2H5OC(O)OH → C2H5OH + CO2 (1b) . Measured DEC decomposition rate constants k(T) at p ≈ 1.5 bar can be represented by the Arrhenius equation k(T) = 1013.64±0.12 exp(−204.24±1.95 kJ/mol/RT) s − 1. Theoretical predictions for k1a were in good agreement with experimentally derived values. The theoretical analysis also included dipropyl carbonate (C3H7OC(O)OC3H7; DPC) decomposition and the reactivities of DEC and DPC are compared and discussed in the context of reactivity of dialkyl carbonates under pyrolytic conditions.

Understanding the combustion of methyl esters is crucial to elucidate kinetic pathways and predict combustion parameters, soot yields, and fuel performance of biodiesel, however most kinetic studies of methyl esters have focused on smaller, surrogate model esters. Methyl hexanoate is a larger methyl ester approaching the chain length of methyl esters found in biodiesel and has not received as much research attention as other smaller esters. The purpose of this work is to present the first atmospheric pressure combustion data of methyl hexanoate, CH3CH2CH2CH2CH2COOCH3. Mixtures of 2% methyl hexanoate in O2 and N2 are studied using a plug flow reactor at atmospheric pressure, wall temperatures from 573 to 973 K, residence times from roughly 1-2 s., and fuel equivalence ratios of 1, 1.5, and 2. Exhaust gases are analyzed by a gas chromatograph-mass spectrometer system and species mole fractions are presented. The literature model shows satisfactory agreement with the experimental species profiles and improvements for future mechanistic studies are suggested. In particular, this work proposes new unimolecular decomposition pathways of methyl hexanoate to form methanol or methyl acetate. Furthermore, the experiment detected three unsaturated esters that are direct products of the low temperature oxidation chemistry and it provides more insight into branching ratios for the formation of methyl hexanoate radicals and for the decomposition of hydroperoxyalkyl radicals.

To fully master a scaled-up combustion synthesis of nanoparticles toward a wide library of materials with tailored functionalities, a detailed understanding of the underlying kinetic mechanism is r...

Spatially and temporally resolved information on thermochemical conditions in hydrocarbon/air flames requires concentration and temperature data obtained by spontaneous Raman/Rayleigh scattering. During the combustion of renewable and more complex fuels, such as ethanol, partially oxidized hydrocarbons are created as intermediates in concentrations large enough to have an influence on the turbulence-chemistry interaction. To obtain concentrations and temperature in flames at atmospheric pressure with a high spatial and temporal resolution, information on the temperature dependent shape and scattering cross section of the major as well as the minor intermediate species is required. Therefore, a novel gas heater based on mixing the hydrocarbons with helium at high temperatures in combination with a multipass Raman spectrometer were developed, able to characterize ro-vibrational Raman scattering of gaseous ethanol in the gaseous phase up to high temperatures and in different spectral regions. The setup is described, its performance evaluated and Raman spectra of gaseous ethanol at atmospheric pressure up to high temperatures is demonstrated.

Following various immunotherapies, lack of proper anti-tumor immune responses is considered as one of the significant problems in novel cancer therapeutic approaches. The expression of inhibitory checkpoint molecules on tumor-infiltrating T cells is one of the main reasons for the ineffectiveness of various immunotherapies. Therefore, we decided to inhibit two of the most important immune checkpoints expressed on T cells infiltrated in tumors, including PD-1 and A2aR. Ligation of PD-1 with PD-L1 and A2aR with adenosine significantly suppress T cell responses against tumor cells. On the other hand, in the tumor area, specific inhibition of these molecules in T cells is of particular importance for successful immunotherapy as well as the elimination of treatment side-effects. Thus, in this study, superparamagnetic iron oxide (SPION) nanoparticles (NPs) were covered by chitosan lactate (CL), functionalized with TAT peptide, and finally these NPs were loaded with siRNA molecules against PD-1 and A2aR. Appropriate physicochemical properties of the prepared NPs resulted in efficient delivery of siRNA to tumor-derived T cells and suppressing the expression of A2aR and PD-1 molecules, ex vivo. T cell functions such as cytokine secretion and proliferation were considerably enhanced by the downregulation of these molecules which led to an increase in their survival time. Interestingly, treatment of CT26 and 4T1 mouse tumor models by siRNA-loaded NPs not only inhibited tumor growth but also markedly increased anti-tumor immune responses and survival time. The results strongly represent the efficacy of SPION-CL-TAT NPs loaded with anti-PD-1/A2aR siRNAs in cancer therapy that can be further considered in cancer patients in the near future.

Boron has been of considerable interest as fuel for propellants and explosives due to its high gravimetric and volumetric calorific values. In this study, the effects of different mixed modes, blending ratios, and packing densities on ignition and combustion characteristics of boron-aluminum mixture were explored using flash ignition facility and thermobalance. The results showed that the boron nanoparticles can be ignited upon exposure to the flash with a certain amount of aluminum nanoparticles addition and the flame luminous intensity increased with content of the added aluminum. The boron-aluminum mixture in loose contact performed better combustion characteristics than those in tight contact because of more access to the oxygen and less heat dissipation into the bulk sample. The main combustion products were detected and analyzed by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The temperatures of the ignited nanoparticles were measured and mostly distributed between 1273 K and 1473 K. The burning time decreased significantly with the increase of aluminum addition at the high packing density condition. The boron combustion efficiency increased with the addition of aluminum content in loose contact. The thermogravimetric experimental results showed that the aluminum addition could decrease the primary ignition temperature of boron. Moreover, the photothermal effect and plasmon resonance effect of aluminum were the potential flash ignition mechanism of the boron-aluminum mixture.

The potential of dimethyl ether (DME) and dimethoxymethane (DMM), representatives of the attractive oxymethylene ether (OME) alternative fuel family, are explored here as reactivity enhancers for methane-fueled polygeneration processes. Typically, such processes that can flexibly generate power, heat, or chemicals, operate under fuel-rich conditions in gas turbines or internal combustion engines. To provide a consistent basis for the underlying reaction mechanisms, it is recognized that speciation data for the DME/CH4 fuel combination are available for such conditions while such information for the DMM/CH4 system is largely lacking. In addition, it should be noted that a detailed speciation study in flames, i.e., combustion systems involving chemistry and transport processes over a large temperature range, is still missing in spite of the potential of such systems to provide extended species information. In a systematic approach using speciation with electron ionization molecular-beam mass spectrometry (EI-MBMS), we thus report, as a first step, investigation of six fuel-rich premixed flames of DME and DMM and their blends with methane with special attention on interesting chemicals. Secondly, a comprehensive but compact DME/DMM/CH4 model (PolyMech2.1) is developed based on these data. This model is then examined against available experimental data under conditions from various facilities, focusing preferentially on elevated pressure and fuel-rich conditions. Comparison with existing literature models is also included in this evaluation. Thirdly, an analysis is given on this basis, via the extensively tested PolyMech2.1 model, for assumed polygeneration conditions in a homogeneous charge compression ignition (HCCI) engine environment. The main interest of this model-assisted exploration is to evaluate whether addition of DME or DMM in a polygeneration process can lead to potentially useful conditions for the production of syngas or other chemicals, along with work and heat. The flame results show that high syngas yields, i.e., up to similar to 78% for CO and similar to 35% for H-2, can be obtained in their burnt gases. From the large number of intermediates detected, predominantly acetylene, ethylene, ethane, and formaldehyde show yields of 2.1-4.4% (C-2 hydrocarbons) and 3.4-8.7% (CH2O), respectively. Also, methanol and methyl formate show comparably high yields of up to 0.6-6.7% in the flames with DMM, which is 1-2 orders of magnitude higher than in those with DME as the additive. In the modeling-assisted exploration of the engine process, the PolyMech2.1 model is seen to perform at significantly reduced computational costs compared to a recently validated model without sacrificing the prediction performance. Promising conditions for the assumed polygeneration process using fuel combinations in the DME/DMM/CH4 system are identified with attractive syngas yields of up to 77% together with work and heat output at exergetic efficiencies of up to 89% with DME. (C) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

A combinatorial approach was applied to devise a set of reference Si–C–O–H species that is used to derive group-additivity values (GAVs) for this class of molecules. The reference species include 62 stable single-bonded, 19 cyclic, and nine double-bonded Si–C–O–H species. The thermochemistry of these reference species, that is, the standard enthalpy of formation, entropy, and heat capacities covering the temperature range from 298 to 2000 K was obtained from quantum chemical calculations using several composite methods, including G4, G4MP2, and CBSQB3, and the isodesmic reaction approach. To calculate the GAVs from the ab initio based thermochemistry of the compounds in the training set, a multivariable linear regression analysis is performed. The sensitivity of GAVs to the different composite methods is discussed, and thermodynamics properties calculated via group additivity are compared with available ab initio calculated values from the literature.

Nanomaterials (NMs) can be produced in plenty of variants posing several challenges for NM hazard and risk assessment. Metabolomic profiling of NM-treated cells and tissues allows for insights into underlying Mode-of-Action (MoA) and offers several advantages in this context. It supports the description of Adverse Outcome Pathways (AOPs) and, therefore, tailored AOP-based hazard testing strategies. Moreover, it bears great potential for biomarker discovery supporting toxicity prediction. Here, we applied metabolomics profiling to cells treated with four well-selected SiO2 variants, differing in structure, size and surface charge. TiO2 NM-105 served as a benchmark. Responses were studied in vitro in rat lung epithelial cells (RLE-6TN) and alveolar macrophages (NR8383) and compared to in vivo responses in rat lung tissues obtained from in vivo instillation and short-term inhalation studies (STIS). Time- and concentration-dependent changes were observed in both in vitro models but with cell-type specific responses. Overall, the levels of lipids and biogenic amines (BAs) tended to increase in epithelial cells but decreased in macrophages. Many identified metabolites like Met-SO, hydroxy-Pro and spermidine were related to oxidative stress, indicating that oxidative stress contributes to the MoA for the selected NMs. Several biomarker candidates such as Asp, Asn, Ser, Pro, spermidine, putrescine and LysoPCaC16:1 were identified in vitro and verified in vivo. In this study, we successfully applied a metabolomics workflow for in vitro and in vivo samples, which proved to be well suited to identify potential biomarkers, to gain insights into NM structure–activity relationship and into the underlying MoA.

Nanocrystalline nickel-iron layers are produced electrochemically on copper discs by varying the current density and then annealed in a vacuum furnace at a temperature range between 200 and 800 °C. Grain size, iron content, texture and microstrain of the microstructure are primarily characterized by X-ray diffraction (XRD). Instrumented indentation tests and microbending tests for mechanical characterization are carried out. The iron contents of the investigated layers are 5.7, 8.8, 13.5 and 17.7 wt.-%. By varying the annealing temperature, the reduction of the microstrains is initiated at 200 °C and ends at a temperature of about 280 °C. Primary recrystallization starts slightly higher at 220 °C and is completed at 300 °C. With higher iron content, the indicated temperatures shift to slightly higher values. Indentation modulus, Young's modulus, indentation hardness and strength change considerably after the annealing treatment. Fracture strain at the edge, as a measure of ductility, decreases immediately after annealing at 200 °C to 0 %. Low annealing temperatures occurring before the beginning of primary recrystallization lead to an increase in indentation hardness and 0.01-% offset bending yield strength Rp0.01∗ as compared to the electrochemically deposited initial state. After annealing at high temperatures, the mechanical parameters are mostly below the initial values for electrochemical deposition. Hall-Petch (HP) behavior is observed for Rp0.01∗, both for the electrochemically deposited specimens down to almost 6 nm and for the specimens annealed at high temperatures. Specimens annealed at low temperatures deviate from the HP straight line to higher values. In this case, an increase in strength is assumed to be due to the very small nanocrystalline (nc) grain sizes, segregation at the grain boundaries and a decrease in dislocation density. Indentation hardness measurements show almost no dependence on D−0.5 for the electrochemically deposited specimens and also for annealed specimens below 30nm grain size. Above 30nm, the indentation hardness values are considerably higher than for the HP straight line. Overall, the hardness and strength values of the nc specimens, electrochemically deposited or additionally annealed, are significantly higher than those of the microcrystalline (mc) specimens.

Titanium(IV) isopropoxide (TTIP) is an important precursor for the production of nanoparticles by spray flame processes. In these processes, the precursor is provided in a solution in a combustible solvent, which is p-xylene here. As no thermophysical data for solutions of TTIP in p-xylene were available in the literature, they were measured in the present work. The vapor–liquid equilibrium was measured at pressures ranging from 20 to 80 kPa. The specific density, viscosity, thermal conductivity, molar isobaric heat capacity, and self-diffusion coefficients were determined experimentally at 101.3 kPa at temperatures between 293.15 and 373.15 K. Sample compositions cover the range from pure TTIP to pure p-xylene. Chemical reactions in the studied system were considered. The experiments were carried out in such a way that they do not compromise the results for the thermophysical properties. The vapor–liquid equilibrium data were correlated using the NRTL model. Empirical correlations were established for the other properties. The results provide a rational basis for spray flame process design.

This work develops flamelet tabulation methods for solid fuel combustion with and without fuel-bound nitrogen based on computations in particle-laden counterflow flames. The proposed flamelet tabulation methods for NO prediction are evaluated for two different coal types. The results show that extracting the NO mass fraction from the flamelet library directly results in significant discrepancies in the studied fuel nitrogen-free flame, while reasonable predictions can be obtained by using the same method in the fuel-bound nitrogen flames for both coal types. In contrast, solving a transport equation for the NO mass fraction tends to improve the NO prediction. The NO concentration is well predicted by splitting the NO source term into a formation part and a rescaled consumption part. The best NO prediction is obtained by extracting the formation part and the rescaled consumption part with a modified reaction progress variable.

Background Nanomaterials (NMs) can be fine-tuned in their properties resulting in a high number of variants, each requiring a thorough safety assessment. Grouping and categorization approaches that would reduce the amount of testing are in principle existing for NMs but are still mostly conceptual. One drawback is the limited mechanistic understanding of NM toxicity. Thus, we conducted a multi-omics in vitro study in RLE-6TN rat alveolar epithelial cells involving 12 NMs covering different materials and including a systematic variation of particle size, surface charge and hydrophobicity for SiO2 NMs. Cellular responses were analyzed by global proteomics, targeted metabolomics and SH2 profiling. Results were integrated using Weighted Gene Correlation Network Analysis (WGCNA). Results Cluster analyses involving all data sets separated Graphene Oxide, TiO2_NM105, SiO2_40 and Phthalocyanine Blue from the other NMs as their cellular responses showed a high degree of similarities, although apical in vivo results may differ. SiO2_7 behaved differently but still induced significant changes. In contrast, the remaining NMs were more similar to untreated controls. WGCNA revealed correlations of specific physico-chemical properties such as agglomerate size and redox potential to cellular responses. A key driver analysis could identify biomolecules being highly correlated to the observed effects, which might be representative biomarker candidates. Key drivers in our study were mainly related to oxidative stress responses and apoptosis. Conclusions Our multi-omics approach involving proteomics, metabolomics and SH2 profiling proved useful to obtain insights into NMs Mode of Actions. Integrating results allowed for a more robust NM categorization. Moreover, key physico-chemical properties strongly correlating with NM toxicity were identified. Finally, we suggest several key drivers of toxicity that bear the potential to improve future testing and assessment approaches.

Sodium-ion batteries (NIBs) utilise cheaper materials than lithium-ion batteries (LIBs), and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterise LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimise cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge.

Fuel-rich operated HCCI engines are suitable for the polygeneration of work, heat, and base chemicals like synthesis gas (CO + H2). Under favorable conditions, these engines are exergetically more efficient than separate steam reformer and cogeneration gas engines. However, to achieve ignition, reactive fuel additives like dimethyl ether or ozone must be supplied, which have some, probably negative and not yet quantified, impacts on the exergetic efficiency.

Reusing wastewater from oil-related industries is becoming increasingly important, especially in water-stressed oil-producing countries. Before oily wastewater can be discharged or reused, it must be properly treated, e.g., by membrane-based processes like ultrafiltration. A major issue of the applied membranes is their high fouling propensity. This paper reports on mitigating fouling inside ready-to-use ultrafiltration hollow-fiber modules used in a polishing step in oil/water separation. For this purpose, in-situ polyzwitterionic hydrogel coating was applied. The membrane performance was tested with oil nano-emulsions using a mini-plant system. The main factors influencing fouling were systematically investigated using statistical design of experiments.

Catalyst layers (CL), as an active component of the catalyst coated membrane (CCM), form the heart of the proton electrolyte membrane fuel cell (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as CL precursors need to be modulated, which are then applied onto a membrane to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods, which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of the inks. Herein, we introduce new concepts, S score, and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.

Dry gas lubricated non-contacting mechanical seals (DGS) are acknowledged as the sophisticated shaft end sealing solution which is most commonly found in turbo-compressors. Especially under demanding conditions where high speed is combined with high pressure, DGS becomes the preferred choice over other sealing alternatives. A reliable operation of DGS, due to the non-contact running between its rotating and stationary rings, is secured by the gas film in the region of a few microns in thickness. This paper presents the measurement method of obtaining the thickness of the running gap in two radial positions, namely the inner and outer diameter of the sealing gap, by integrating the proximity sensors in the stationary ring. The experimental investigations concerning film thicknesses, pressure distributions in the gas film and axial vibrations are carried out in an industry DGS up to 50 bar and 10,000 rpm, whereby a good insight into the dynamic behaviour of the sealing gap is provided. The results demonstrate the practicability of obtaining the gas film parameters in a grooved gas seal, bridging the gap between theory and practice. In combination with the experimental work presented in this paper, the numerical model for simulating the seal performance programmed in MATLAB is compared and validated. The comparisons for various operating conditions and groove profiles are discussed with the focus lying on the hydrodynamic effect in the gas film.

Considering automated driving, vehicle dynamics control systems are also a crucial aspect. Vehicle dynamics control systems serve as an important influence factor on safety and ride comfort. By reducing the driver’s responsibility through partially or fully automated driving functions, the occupants’ perception of safety and ride comfort changes. Both aspects are focused even more and have to be enhanced. In general, research on vehicle dynamics control systems is a field that has already been well researched. With regard to the mentioned aspects, however, a central control structure features sufficient potential by exploiting synergies. Furthermore, a predictive mode of operation can contribute to achieve these objectives, since the vehicle can act in a predictive manner instead of merely reacting. Consequently, this contribution presents a central predictive control system by means of a non-linear model-based predictive control algorithm. In this context, roll, self-steering and pitch behavior are considered as control objectives. The active roll stabilization demonstrates an excellent control quality with a root mean squared error of 7.6953×10−3 rad averaged over both validation maneuvers. Compared to a vehicle utilizing a conventional control approach combined with a skyhook damping, pitching movements are reduced by 19.75%. Furthermore, an understeering behavior is maintained, which corresponds to the self-steering behavior of the passive vehicle. In general, the central predictive control, thus, increases both ride comfort and safety in a holistic way.

Fluorescence spectra and lifetimes of anisole and toluene vapor in nitrogen have been measured at conditions below ambient (257–293 K and 100–2000 mbar) upon excitation with 266-nm laser light to expand the applicable range of anisole and toluene laser-induced fluorescence (LIF) for conditions below room temperature that occur in expanding flows and cases with strong evaporative cooling. Anisole fluorescence spectra broaden with decreasing pressure while fluorescence lifetimes decrease simultaneously. This is consistent with a more pronounced effect of internal vibrational redistribution on the overall fluorescence signal and can be explained by significantly reduced collision rates. In the case of toluene, the transition from photo-induced heating to photo-induced cooling was observed for the first time for 266 nm. The data confirm predictions of earlier work and is particularly important for the advancement of the available photo-physical (step-ladder) models: since those transitions mark points where the molecules are already thermalized after excitation (i.e., no vibrational relaxation occurs during deactivation), they are important support points for fitting empirical parameters and allow analytical determination of the ground state energy transferred to the excited state. The data enable temperature and/or pressure sensing, e.g., in accelerating cold flows using laser-induced fluorescence of both tracers.

In the pyrolysis of different hydrocarbon/carbon suboxid fuels formation of carbon particles with the special view to their structures was examined. For this, the following three very different pyrolysis systems were investigated experimentally i) a pyrolysis reactor, ii) a shock tube and iii) a plasma reactor with respect to the influence of varying reaction parameters on the carbonaceous nanoparticles. The particles formed in these reaction systems were studied in view of their morphology and state of crystallization by use of electron microscopy (Philips CM30) at low- and high resolution combined with micro-diffraction measurements. As to be seen at low resolution of the transmission electron microscopy studies, the particle sizes in the pyrolysis reactor and shock tube do not differ significantly, but distinguished considerably from those particle sizes obtained in the plasma reactor. While the particles obtained in the pyrolysis reactor and shock-tube had particle diameters of about d ≈ 30 nm, the particles in the plasma reactor consisted of fluffy-like units, and their sizes were about d ≈ 4 nm. The various carbon layers consisted of different polyaromatic hydrocarbon units with variable sizes arranged to diverse states in the course of graphitization.

Biopersistent pro-inflammatory fibers are suspected human carcinogens. Cytotoxicity and transcription of pro- and anti-inflammatory mediators of different fibers were investigated in functional relationship to chemotaxis in vitro as a model for fiber-induced inflammation of the lung. We challenged NR8383 rat macrophages with multi-walled carbon nanotubes (MWCNT) and various asbestos fibers. The resulting cell supernatants were than studied using the Particle-induced Cell Migration Assay (PICMA) and cytotoxicity was determined using the LDH test. Expression of inflammatory mediators was analyzed with qPCR and verified by ELISA. Chrysotile A and the rigid, needle-shaped NM-401 caused the strongest cytotoxic effects and the largest number of migrated cells. In contrast, the MWCNT NM-400, NM-402, and NM403 were apparently non-cytotoxic but induced pronounced cell migration showing a very steep dose response. However, the strength of cell migration and cytotoxicity of the asbestos fibers were correlated. The expression profile of inflammatory mediators was comparable, although cytotoxicity of the MWCNT NM-401 and NM-403 differed strongly. Induction of the corresponding proteins was confirmed for CCL2, CCL3, CXCL1, CXCL3, IL1RA (IL1RN), CSF1, GDF15 and TNFa. Chrysotile A and NM-401 induced much stronger chemotaxis than the non-fibrous particles reported in our previous study. Cytotoxic and chemotactic effects correspond to the induction of inflammatory mediators.

The homogeneous partial oxidation of methane is an interesting approach to obtain useful chemicals like synthesis gas, higher hydrocarbons, aldehydes or alcohols. Because of the low reactivity of methane, the homogeneous conversion needs high temperatures to proceed at reasonable reaction rates. Additives like n-heptane form reactive intermediates at comparatively low temperatures and initiate the conversion. To study the kinetics of doped conversion reactions, fuel-rich diluted methane/n-heptane/oxygen/argon-mixtures (2 ≤ Φ ≤ 20) were investigated in a plug-flow reactor at a pressure of 6 bar, at intermediate temperatures between 423 and 973 K and at relatively long residence times (7 ≤ τ ≤ 14 s). The product composition at the reactor outlet is analyzed by gas chromatography and mass spectrometry. Species profiles as a function of equivalence ratio and temperature are compared with simulations, and serve as validation data for different reaction mechanisms. Rates of production and reaction paths are analyzed to investigate the interaction of methane and n-heptane during the oxidation process. They show that the chemical interaction of the oxidation products of both fuels has a promoting effect on the formation of different useful products like carbon monoxide, methanol or ethane. To prove this observation, mole fraction profiles as a function of temperature were compared between experiments with an equivalence ratio of Φ = 8 using neat methane, neat n-heptane and methane/n-heptane mixtures as fuels. The results show that the yields of these species are much higher in case of the methane/n-heptane mixture compared to the yields obtained in the neat methane and neat n-heptane conversions or the sum of both.

During the adsorptive separation of light hydrocarbons in the trace range, significant coadsorption of the carrier gas may occur due to low temperatures and much higher concentrations of the carrier gas compared to the adsorptive. This results in a reduction of the adsorbent’s capacity, which leads to problems in industrial adsorber design and an incorrect interpretation of adsorption mechanisms. So far, there are only few studies on the carrier gas influence, and no data exist for low temperatures. In this work, we present experimental adsorption isotherms of methane and ethane from nitrogen and helium at temperatures between −80 and +20 °C on activated carbon and zeolite 13X. A comparison of the adsorption isotherms and the isosteric adsorption enthalpy reveals that coadsorption increases strongly with low temperatures, low partial pressures, and weak interactions between adsorptive and adsorbent. Finally, coadsorption is shown to be stronger on activated carbon than on zeolite 13X.

The objective of this study is to infer Drude model parameters for liquid germanium nanoparticles from extinction measurements made across an aerosol within a microwave plasma reactor using a halogen lamp (410–700 nm) and a laser-driven light source (205–585 nm). The plasma frequency and relaxation time are inferred using Rayleigh theory, Mie theory, and a fourth-order Mie approximation. These parameters are compared with those found using the ellipsometry-derived complex dielectric function as well as the bulk density and electrical resistivity of liquid germanium. The analysis is carried out in a probabilistic context using Bayesian inference, which accounts for both the measurement noise and model error. While all the candidate models can reproduce the shape of the experimentally-derived extinction spectra, the Bayesian inference showed that extinction-derived parameters differed from those obtained from the density and electrical resistivity in a statistically-significant way. This highlights the limitations of the free-electron model that underpins Drude theory, and suggests potential opportunities for model refinement.

This work is devoted to scale-up the microwave plasma synthesis of silicon nanoparticles from gaseous precursor monosilane (SiH4), previously investigated in lab-scale processes, to the pilot-plant-scale with production rates up to 200 g/h. The aim is to ensure reproducible, long-term operation of the reactor through gas-dynamic stabilization of the reacting flow and to control particle size and morphology via the gas flow velocity and the precursor concentration. Based on a newly designed nozzle, the lab-scale approach of stabilizing the plasma flow via a tangential sheath gas flow and an axial precursor gas flow was successfully transferred to the pilot-plant scale. At precursor concentrations up to 16 vol% of SiH4 diluted in argon and hydrogen, the as-synthesized particles have similar characteristics compared to those from lab-scale reactors. They are spherical, crystalline, mostly soft-agglomerated, and show a log-normal size distribution with a geometric standard deviation around 1.45 as expected for self-preserving aerosol size-distributions. In contrast to lab-scale experiments, an increase in SiH4 concentration up to 48 vol% does not lead to further growth of isolated primary particles but promotes aggregate formation from smaller primary particles. This is attributed to massive initial nucleation of very small particles due to strong supersaturation and their subsequent strong aggregation while suppressing complete coalescence due to the limited residence time at high temperature.

Two laminar, premixed, fuel-rich flames fueled by anisole-oxygen-argon mixtures with the same cold gas velocity and pressure were investigated by molecular-beam mass spectrometry at two synchrotron sources where tunable vacuum-ultraviolet radiation enables isomer-resolved photoionization. Decomposition of the very weak O–CH3 bond in anisole (C6H5OCH3) by unimolecular decomposition yields the resonantly-stabilized phenoxy radical (C6H5O). This key intermediate species opens reaction routes to five-membered ring species, such as cyclopentadiene (C5H6) and cyclopentadienyl radicals (C5H5). Anisole is often discussed as model compound for lignin to study the phenolic-carbon structure in this natural polymer. Measured temperature profiles and mole fractions of many combustion intermediates give detailed information on the flame structure. A very comprehensive reaction mechanism from the literature which includes a sub-scheme for anisole combustion is used for species modeling. Species with the highest measured mole fractions (on the order of 10−3–10−2) are CH3, CH4, C2H2, C2H4, C2H6, CH2O, C5H5 (cyclopentadienyl radical), C5H6 (cyclopentadiene), C6H6 (benzene), C6H5OH (phenol), and C6H5CHO (benzaldehyde). Some are formed in the first destruction steps of anisole, e.g., phenol and benzaldehyde, and their formation will be discussed and with regard to the modeling results. There are three major routes for the fuel destruction: (1) formation of benzaldehyde (C6H5CHO), (2) formation of phenol (C6H5OH), and (3) unimolecular decomposition of anisole to phenoxy (C6H5O) and CH3 radicals. In the experiment, the phenoxy radical could be measured directly. The phenoxy radical decomposes via a bicyclic structure into the soot precursor C5H5 and CO. Formation of larger oxygenated species was observed in both flames. One of them is guaiacol (2-methoxyphenol), which decomposes into fulvenone. The presented speciation data, which contain more than 60 species mole fraction profiles of each flame, give insights into the combustion kinetics of anisole.

In direct-injection engines, fuel components of different volatility can segregate in the transient evaporating spray. The resulting spatial mixture inhomogeneities may impact ignition and combustion. The technique presented here images the effect of preferential evaporation of a multi-component gasoline surrogate fuel in an optically-accessible direct-injection engine motored on nitrogen. It is based on laser-induced fluorescence (LIF) of two aromatic tracers with different volatilities, 1,4-difluorobenzene (representing light to medium components) and 1-methylnaphthalene (heavy component) added to a base-fuel of n-pentane, iso-octane, and n-undecane. LIF from the two tracers is spectrally separated and detected on two cameras, with channel crosstalk corrected in post-processing. Consistent with previous measurements in a high-pressure vessel, the light components are preferentially found downstream, towards the front of the evaporated fuel jet. Throughout large regions of the field of view, about 20% surplus of 1-methylnaphthalene is found, and throughout smaller ones about 40% of 1,4-difluorobenzene. To better assess the impact of the (unknown) local temperature on the measurement accuracy, two-color thermometry based on LIF of anisole (methoxybenzene) is performed in separate experiments. In the relevant range of crank-angles the local temperature is found to be 25 K lower in regions of high fuel concentration than in the rest of the charge, implying a systematic temperature-induced error in the fuel-tracer ratio of 0.11.

Nanoparticle formation in flames is strongly influenced by the residence-time–temperature history inside the flame. We study how the temperature history can be intentionally modified by orienting flames either in an upward-firing or downward-firing configuration. We also investigate the influence of unintended residence-time modifications caused by sampling nozzles. These phenomena are investigated by experiments and simulations for the synthesis of iron oxide nanoparticles from premixed iron-pentacarbonyl-doped hydrogen/oxygen flat flames. The experiments apply molecular-beam sampling with a particle mass spectrometer to measure particle sizes and a quartz microbalance to detect the presence of condensed matter. The simulations rely on a finite-rate chemistry approach with species-specific diffusion, particle dynamics are described by a bi-modal population balance model. It is demonstrated that the downward-burning flame forms a detached stagnation point, causing longer residence times at elevated temperature than an upward- or horizontally firing flame, permitting the growth of larger particles. These iron oxide particles are eventually formed in the recombination zone of the flame, but no condensed matter was found in the reaction zone. The experiments also observed the formation of particles in the preheat zone, but their composition and all aspects of their disappearance remain uncertain. Current models do, however, suggest the formation of iron particles and their subsequent evaporation and combustion.

Understanding the chemistry of iron-based metal-organic precursor solutions for spray-flame synthesis is a key step to developing inexpensive and large scale applications for gas-phase synthesized, nano-sized iron oxide particles. Owing to the large variety of available organic solvents and iron compounds, the choice of a suitable precursor-solvent pair is challenging. Systematic investigations of the precursor chemistry of iron-based systems are currently not available. This work aims at filling this gap by providing a detailed spectroscopic analysis of mixtures containing iron(iii) nitrate nonahydrate and alkyl alcohols (C2-4). Moreover, the impact of adding 2-ethylhexanoic acid is explored. The FTIR spectra reveal the formation of carboxylates and allow deriving information about the coordination of the metal-carboxylate complexes. The stability of the precursor solutions is investigated by monitoring precipitation phenomena and turbidity. Furthermore, gas chromatography is employed to provide additional information on oxidation products and esters as well as to aid the interpretation of the FTIR data. It is found that the formation of esters has an enhancing effect on iron sorption and, thus, it promotes precursor stability.

The growth of carbon particles was studied in heated flows of a burnt-gas flow reactor containing mixtures of N2/C2H2, and N2/C2H2 with addition of H2 or CH4 surrounded by a rich C2H4/air flame. Soot particle sizes and volume fractions were measured by laser-induced incandescence (LII) between 50 and 130 mm above the nozzle exit. The measurements indicate a soot-inhibiting effect of adding H2 to the C2H2/N2 flow on both, particle sizes and soot volume fractions. The effect of CH4 addition to the C2H2/N2 flows was ambivalent, depending on the methane-to-acetylene ratio. At gas mixtures with N2:CH4:C2H2 = 0.42:0.35:0.23 and 0.39:0.32:0.29 by volume at fixed total flow rates, the measured soot volume fractions were substantially increased in presence of CH4, while the mean diameters of the particles were slightly decreased. Gas temperatures were measured by a generalized line-reversal method with Abel transformation. Temperatures of the surrounding C2H4/air flame were around 1600 K, and temperatures of the inner flows, where soot formation was measured, were between 1550 and 1630 K. Plug-flow reactor calculations provided a qualitative understanding of the influence of CH4 on the soot particle growth.

The growing societal and political focus on the use of environmentally friendly technologies has led to an ever-increasing interest in electrolysis technologies in the scientific communities. This development is reflected by the plethora of candidate catalysts for the hydrogen and oxygen evolution reactions, as well as the CO2 reduction reaction, reported in the literature. However, almost none of them entered the stage of application yet. Likewise, the reports on process engineering inadequately address the utilization of these catalysts, as well as electrode and cell concepts, that might be suitable for the market. Evidently, a closer collaboration between chemists and engineers from industry and academia is desirable to speed up the development of these disruptive technologies. Herein, we elucidate the critical parameters and highlight the necessary aspects to accelerate the development of industrially relevant catalysts capable of fulfilling the forthcoming challenges related to energy conversion and storage. The aim of this Perspective, composed by industrial and academic partners, is to critically question current undertakings and to encourage researchers to strike interdisciplinary research pathways. CA extern und CA Segets

Methane based polygeneration processes in piston engines offer the possibility of a controllable and flexible conversion of energy, to up-convert low value chemicals and to store energy. These processes preferably take place under fuel-rich conditions and at high pressures. Under fuel-rich conditions, there was one experimental report that a distinctive negative temperature coefficient (NTC) behavior occurs in methane oxidation (Petersen et al., 1999). To design a polygeneration process, reliable kinetic models are required to capture the impact of pressure and equivalence ratio variations on reactivity of the gas mixtures. Here, the experimental basis for methane oxidation is expanded to high pressures and very fuel-rich conditions and compared to literature models, both with special emphasis on the NTC behavior. The oxidation of methane/oxygen mixtures at 2 ≤ Φ≤ 20 and pressures ranging from 1 to 20 bar is investigated. The literature reaction mechanisms are assessed with respect to their ability to predict this phenomenon and used to identify reaction pathways. It is found that NTC behavior occurs in a temperature range between 700 and 1000 K and at pressures higher than 5 bar. The lower temperature limit is slightly shifted towards higher temperatures with decreasing equivalence ratio. In addition, the higher the equivalence ratio, the broader the pressure range, in which the NTC behavior is observed. In general, predictions of some models are in good agreement with the experimental data. Reaction path analyses reveal that the competition between oxidation and recombination pathways are responsible for the NTC region in methane oxidation.

The practical application of silicon-based anodes is severely hindered by continuous capacity fade during cycling. A very promising way to stabilize silicon in lithium–ion battery (LIB) anodes is the utilization of nanostructured silicon-rich silicon nitride (SiNₓ), a conversion-type anode material. Here, SiNₓ with structure sizes in the sub-micrometer range have been synthesized in a hot-wall reactor by pyrolysis of monosilane and ammonia. This work focusses on understanding process parameter–particle property correlations. Further, a model for the growth of SiNₓ nanoparticles in this hot–wall–reactor design is proposed. This synthesis concept is of specific interest regarding simplicity, flexibility, and scalability: A way utilizing any mixtures of precursor gases to build multi-functional nanoparticles that can be directly used for LIBs instead of focusing on modification of nanostructures after they have been formed. Lab-scale production rates as high as 30 g h−¹ can be easily achieved and further scaled. SiN₀.₇ nanoparticles provide a first cycle coulombic efficiency of 54%, a specific discharge capacity of 1367 mAh g−¹, and a capacity retention over 80% after 300 cycles at 0.5 C (j = 0.68 mA cm−²). These results imply that silicon-rich silicon nitrides are promising candidates for high-performance LIBs with very high durability.

The information of the gas phase kinetics are relevant for the development of detailed reaction mechanisms as well as for process design and control in flame synthesis. In this study, the decomposition of iron pentacarbonyl and the reaction pathways towards iron oxide clusters and particles in laminar H2/O2/Ar low-pressure synthesis flames are investigated. Gas-phase species are analyzed by photoionization and electron ionization mass spectrometry. The extraction of a representative sample from the particle-laden flow of a synthesis flame by an intrusive sampling technique for the analysis is challenging, because iron-intermediate species can condense easily. Cations can be extracted from the flame with a high efficient ion sampling technique that results in high sensitivity. Iron-containing cations provide evidence of the presence of key intermediates, e.g., Fe(OH)2, Fe(OH)3, Fe2O3, and larger Fe-O-clusters which are the dominant intermediates with respect to particle formation and need to be considered in future gas-phase reaction mechanisms.