High Temperature Thermal Decomposition Research Articles

Casein-Coated Fe5C2 Nanoparticles with Superior r2 Relaxivity for Liver-Specific Magnetic Resonance Imaging.

Iron oxide nanoparticles have been extensively used as T2 contrast agents for liver-specific magnetic resonance imaging (MRI). The applications, however, have been limited by their mediocre magnetism and r2 relaxivity. Recent studies show that Fe5C2 nanoparticles can be prepared by high temperature thermal decomposition. The resulting nanoparticles possess strong and air stable magnetism, suggesting their potential as a novel type of T2 contrast agent. To this end, we improve the synthetic and surface modification methods of Fe5C2 nanoparticles, and investigated the impact of size and coating on their performances for liver MRI. Specifically, we prepared 5, 14, and 22 nm Fe5C2 nanoparticles and engineered their surface by: 1) ligand addition with phospholipids, 2) ligand exchange with zwitterion-dopamine-sulfonate (ZDS), and 3) protein adsorption with casein. It was found that the size and surface coating have varied levels of impact on the particles' hydrodynamic size, viability, uptake by macrophages, and r2 relaxivity. Interestingly, while phospholipid- and ZDS-coated Fe5C2 nanoparticles showed comparable r2, the casein coating led to an r2 enhancement by more than 2 fold. In particular, casein coated 22 nm Fe5C2 nanoparticle show a striking r2 of 973 mM-1s-1, which is one of the highest among all of the T2 contrast agents reported to date. Small animal studies confirmed the advantage of Fe5C2 nanoparticles over iron oxide nanoparticles in inducing hypointensities on T2-weighted MR images, and the particles caused little toxicity to the host. The improvements are important for transforming Fe5C2 nanoparticles into a new class of MRI contrast agents. The observations also shed light on protein-based surface modification as a means to modulate contrast ability of magnetic nanoparticles.

Magnetic Nanoparticles Activated Carbon: Preparation, Characterization and Application: A Review article

This review focuses on the synthesis, characterization and corresponding application briefly of magnetic nanoparticles activated carbon. Substantial progress in the size and shape control of magnetic nanoparticles activated carbon has been made by developing methods such as Chemical co-precipitation method, High temperature treatment method, Encapsulation, Thermal Decomposition and Hydrothermal Synthesis. The review begins with the synthetic strategies developed for the generation of Magnetic Nanoparticles Activated carbon with a focus on different methodologies for the together with the characterization techniques are explained. Finally, some of the recent biological, biosciences, bio separation, drug delivery, hyperthermia catalysis and environmental applications magnetic nanoparticles activated carbon are briefly reviewed.

Induction of Heat Shock Protein‐72 by Magnetic Nanofluid Hyperthermia in Cultured Retinal Ganglion Cells for Neuroprotective Treatment in Glaucoma

Background. Magnetic hyperthermia using superparamagnetic nanoparticle (SPNP) agents is considered a promising biotechnological approach to induce heat shock proteins (HSPs) in a target tissue because it can generate accurately controllable localized heating. Objectives. The main objective of this study is to demonstrate induction of HSPs in cultured retinal ganglion cells (RGCs) by using engineered Mn0.5Zn0.5Fe2O4 SPNP agents coated with polyethylene glycol (PEG) 500. Methods. The Mn0.5Zn0.5Fe2O4 nanoparticles were synthesized using a high temperature thermal decomposition method. The AC heating characteristics of PEG 500‐coated Mn0.5Zn0.5Fe2O4 nanoparticles were investigated using an AC solenoid coil‐capacitor system. Results. PEG 500‐coated SPNPs efficiently penetrated into the cytoplasm of RGCs without causing obvious cytological changes and showed stable and well‐saturated self‐heating temperature rise characteristics. Immunofluorescent staining images showed that AC magnetic hyperthermia successfully induced HSP72 in RGCs incubated with Mn0.5Zn0.5Fe2O4 nanoparticles. In Western blot analysis, a significant increase in immunoreactivity was observed for RGCs incubated with SPNPs in a fixed AC magnetic field (fappl = 140 kHz and Happl = 140 Oe). Conclusion. Our results demonstrate that the induction of HSP72 with a magnetic nanofluid hyperthermia could potentially be used as a neuroprotective treatment modality by way of enhancing a natural cytoprotective response.

Thermal properties of Co0.5Zn0.5Fe2O4 nanoparticles for hyperthermia applications

Co0.5Zn0.5Fe2O4 nanoparticles (NPs) were prepared by using a high-temperature thermal decomposition method. The crystal structure was found to be cubic spinel with space group Fd − 3m and the lattice constant (a 0) to be 8.40 A by using a Rietveld refinement analysis. Based on the Scherrer equation, we obtained the average size of NPs a 9.4 nm. The magnetic properties were characterized using a vibrating sample magnetometer (VSM) as well as external magnetic field Mossbauer spectroscope taken at 4.2 K. The saturation magnetization (M s ) and coercivity (H c ) of the NPs were 78.7 emu/g and 21.0 Oe, respectively. The thermal properties of the NPs were measured by using a magneTherm device within the physiologically safe ranges of the frequency and the amplitude. The self-heating temperatures of the NPs were found to be 104 and 119 °C at 50 and 112 kHz, respectively, under on applied field of 25 mT.

Modeling and optimization of a sono-assisted photocatalytic water treatment process via central composite design methodology

This work focuses on modeling and optimization of a sono-assisted photocatalytic decolorization process of a model pollutant, azo dye C.I. direct red 16 (DR16). In the process, a high temperature thermal decomposition nano synthesized titanium dioxide (TD-TiO2) was applied as photocatalyst. Central composite design (CCD) methodology was used for designing the experiments, modeling and optimization of the process. A quadratic model was established to describe dependency of the decolorization efficiency (DE), as the model response, to some effective operational parameters, i.e. the catalyst dosage, pH and the dye initial concentration. The ANOVA analysis confirmed that all of the variables have significant influence on the model response. Under the established optimum conditions, 92.4% DE was achieved after 45min; however, to access desirable mineralization efficiency, the process should be continued up to 120min. All withdrawn samples from the reaction media during the process showed no antibacterial activity, which indicates safety of the treated effluent for disposal into the environment. Also studies showed that the process proceeds via two parallel branches of photolysis and photocatalysis, where propagation of the ultrasonic waves into the reaction media plays a vital promoting role on the latter branch.

Synthesis, polymerization, and properties of the allyl‐functional phthalonitrile

ABSTRACTA novel bisphthalonitrile monomer containing allyl groups (DBPA‐Ph) had been synthesized via the reaction of diallyl bisphenol A (DBPA) and 4‐nitrophthalonitrile. The chemical structure of DBPA‐Ph was confirmed by 1HNMR, 13CNMR, and FTIR spectroscopy. The curing behaviors and processability of DBPA‐Ph were studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the polymerization of allyl groups and the second to the ring‐form polymerization of cyano groups. The result of dynamic rheological analysis indicated the monomer had wide curing window and the self‐catalyzed curing behavior. DBPA‐Ph polymers were prepared from the thermal polymerization with short curing time, showing high glass transition temperature (>350°C) and attractive thermal decomposition temperature (>430°C). The outstanding glass transition temperature, desirable thermo‐oxidative stabilities, good processability and sound process conditions could provide more applications to the DBPA‐Ph polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41203.

How nanocrystallinity and order define the magnetic properties of ε-Co supracrystals

Single domain cubic ε-Co nanocrystals are synthesized via a high-temperature thermal decomposition of cobalt carbonyl in the presence of oleic acid and trioctylphosphane oxide (TOPO). The ε-Co nanocrystals are characterized by a low size distribution (σ < 7%) and the average diameter is tuned from 7 nm to 9 nm by tailoring the molar ratio of the surfactants oleic acid and TOPO. Moreover, we have demonstrated the self-assembly of ε-Co nanocrystals in highly ordered three-dimensional (3D) face-centered cubic (fcc) structures called supracrystals. The layer-by-layer organization of these building blocks is achieved through solvent evaporation. Simultaneously, we produce. with the same ε-Co nanocrystals, disordered (amorphous) films. We demonstrate the presence of large interparticle magnetic interactions in the supracrystals by comparing their magnetic properties with the diluted samples. Then, by a detailed comparison of their collective magnetic properties with partially disordered films, the significant differences due to the change in anisotropy and distribution of dipolar interaction energies in the two systems are presented. This is attributed to the orientational and spatial ordering of single domain ε-Co nanocrystals markedly changing between ordered and disordered assemblies. The thermal evolution of the magnetization in ZFC/FC procedure presents three characteristic temperatures representing the blocking, the irreversibility and the maximum of Zeeman coupling temperatures. They are all affected by the presence of the order in supracrystals and they present different evolution trends as a function of nanoparticles size. While the variations of reduced remanent magnetizations in both condensed series are in good agreement with the previous theoretical calculations, the coercive fields present opposite evolutions.

Preparation and upconversion luminescence of beta-NaYF4:Yb3+, Tm3+/ZnO nanoparticles.

Beta-NaYF4:Yb3+, Tm3+/ZnO core/shell nanoparticles (NPs) were synthesized via a high temperature thermal decomposition method. The as-synthesized core/shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and upconversion luminescence spectra (UCL). Under 980 nm laser excitation, the measured intensity of upconversion luminescence (1I6 --> 3H6, 1I6 --> 3F4, and 1D2 --> 3H6) was different with and without ZnO. During the sample preparations, changing the ratio of the solvent affected the ZnO UV absorption efficiency. The results show that the NIR light can be used as the driving source to excite ZnO, thus extending utility rate to the NIR spectral region and enhancing the light harvest rate.

Ultraviolet upconversion emissions of Gd3+ in beta-NaLuF4:Yb3+,Tm3+,Gd3+ nanocrystals.

Beta-NaLuF4:20%Yb,0.5%Tm,x%Gd (x = 10, 20, 30) nanocrystals were synthesized by high temperature thermal decomposition method. X-ray diffraction (XRD) show the as-prepared samples are characteristic of a pure beta-NaLuF4. Transmission electron microscope (TEM) investigations indicate the nanocrystals have particle size of -85 nm with good monodispersity and well-defined crystallographic facets. Particularly, under 980 nm excitation, upconversion (UC) emissions in the UV range of 270-320 nm were observed in these nanocrystals, which further prove that beta-NaLuF4 is an excellent host for building UV compact solid-state lasers or fiber lasers.

Direct Dynamics Simulation of the Activation and Dissociation of 1,5-Dinitrobiuret (HDNB)

Certain room-temperature ionic liquids exhibit hypergolic activity as liquid bipropellants. Understanding the chemical pathways and reaction mechanisms associated with hypergolic ignition is important for designing new fuels. It has been proposed (J. Phys. Chem. A 2008, 112, 7816) that an important ignition step for the hypergolic ionic liquid bipropellant system of dicyanamide/nitric acid is the activation and dissociation of the 1,5-dinitrobiuret anion DNB(-). For the work reported here, a quasiclassical direct dynamics simulation, at the DFT/M05-2X level of theory, was performed to model H(+) + DNB(-) association and the ensuing unimolecular decomposition of HDNB. This association step is 324 kcal/mol exothermic, and the most probable collision event is for H(+) to directly scatter off of DNB(-), without sufficient energy transfer to DNB(-) for H(+) to associate and form a highly vibrationally excited HDNB molecule. Approximately 1/3 of the trajectories do form HDNB, which decomposes by eight different reaction paths and whose unimolecular dynamics is highly nonstatistical. Some of these paths are the same as those found in a direct dynamics simulation of the high-temperature thermal decomposition of HDNB (J. Phys. Chem. A 2011, 115, 8064), for a similar total energy.

Kinetic Pathways To Control Hydrogen Evolution and Nanocarbon Allotrope Formation via Thermal Decomposition of Polyethylene

Polyethylene-based plastic materials are nonbiodegradable in nature and have a profound negative impact on our environment. Efficient disposal of plastic wastes in an efficient, environmental friendly fashion or chemical fixation of plastics into useful intermediates remains an outstanding problem. We employ temperature accelerated reactive molecular dynamics (TARMD) simulations to identify the kinetic pathways during thermal pyrolysis of polyethylene (PE). This allows for attainment of a dual objective viz. (1) clean fuel production via controlled hydrogen evolution and (2) formation of novel nanocarbon allotropes. Detailed atomistic picture of high temperature thermal decomposition that leads to partial or complete dehydrogenation of PE is presented. We identify the various reaction pathways for PE decomposition at high temperatures and demonstrate that a quenching-cooling strategy holds promise for tailoring the degree of graphitic order within the nanocarbon materials while simultaneously fine-tuning the evolution of clean fuel such as hydrogen gas. TARMD simulation trajectories elucidate the effect of simulated kinetic pathways on the reactive decomposition into hydrogen/flue gas/carbon, gas–liquid–solid phase separation of reaction products, interface dynamics, nucleation, and microstructural evolution of carbon particles. Depending on the quenching rate and the residual hydrogen content, we show that it is kinetically possible to control the reaction pathways and diffusion mechanisms and selectively produce a wide gamut of carbon allotropes (carbon onions, spheres, rods, graphene sheets to name a few). Suitable comparisons are made between simulation and our experimental results. Our simulations illustrate an environmental friendly strategy for controlled synthesis of nanocarbon materials and simultaneous clean energy production from nonbiodegradable products.

Effect hyperthermia in CoFe2O4@MnFe2O4 nanoparticles studied by using field-induced Mössbauer spectroscopy

CoFe2O4@MnFe2O4, with a mixed core-shell structure was fabricated by a high temperature thermal decomposition. From the Rietveld refinement, these nanoparticles were found to be cubic spinel with space group Fd-3m and with a Bragg factor (R B ) and a structure factor (R F ) less than 5%. The size and the shape of the nanoparticles were examined with high-resolution transmission electron microscopy (HR-TEM). The values of the magnetization (M S ) and the coercivity (H C ) of these nanoparticles at room temperature were 78.95 emu/g and 21.2 mT, respectively. The effect of hyperthermia, measured with a magneTherm device showed that the self-heating temperature of the nanoparticles could reach 133 °C. To determine the applicability of nanoparticles in hyperthermia therapy, we evaluated the in-vitro cell viability of nanoparticles. Based on the probability distribution of cations, we determined the Mossbauer spectra at 4.2 K with two sets of six lines under various applied fields parallel to the direction of the γ-rays. To separate the A and the B sites, we also obtained the Mossbauer spectra of the nanoparticles under high external field up to 5 T at 4.2 K. From the detailed analysis of the Mossbauer spectra, the spin canting angles and the anisotropy energies at the A and the B sites were determined.

Size-controlled monodisperse hydrophobic and hydrophilic magnetite nanoparticles: One-pot synthesis, characterization, and the mechanism study

Depending on whether to add oleic acid in the reaction system, monodisperse magnetite nanoparticles with hydrophobicity and hydrophilicity are prepared by one-step “polyolthermal reaction”. Combined techniques of TEM, XRD, XPS and FTIR are used to characterize the obtained nanoparticles. The diameter of nanoparticles can be tuned easily by a simple change in the reaction time and the concentration of iron precursor. The method proposed here combines all the advantages of the high-temperature thermal decomposition method and the solvothermal process. Details about formation processes of magnetite nanoparticles are studied using UV–vis absorption spectrum. The result shows a different nucleation procedure and nucleation time for oil-soluble and water-soluble nanoparticles due to the presence of oleic acid. Magnetic properties of the prepared magnetite nanoparticles are also measured on vibrating sample magnetometer at room temperature.

High Temperature Shock Tube and Theoretical Studies on the Thermal Decomposition of Dimethyl Carbonate and Its Bimolecular Reactions with H and D-Atoms

The shock tube technique was used to study the high temperature thermal decomposition of dimethyl carbonate, CH3OC(O)OCH3 (DMC). The formation of H-atoms was measured behind reflected shock waves by using atomic resonance absorption spectrometry (ARAS). The experiments span a T-range of 1053-1157 K at pressures ∼0.5 atm. The H-atom profiles were simulated using a detailed chemical kinetic mechanism for DMC thermal decomposition. Simulations indicate that the formation of H-atoms is sensitive to the rate constants for the energetically lowest-lying bond fission channel, CH3OC(O)OCH3 → CH3 + CH3OC(O)O [A], where H-atoms form instantaneously at high temperatures from the sequence of radical β-scissions, CH3OC(O)O → CH3O + CO2 → H + CH2O + CO2. A master equation analysis was performed using CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties for all thermal decomposition processes in DMC. The theoretical predictions were found to be in good agreement with the present experimentally derived rate constants for the bond fission channel (A). The theoretically derived rate constants for this important bond-fission process in DMC can be represented by a modified Arrhenius expression at 0.5 atm over the T-range 1000-2000 K as, kA(T) = 6.85 × 10(98)T (-24.239) exp(-65250 K/T) s(-1). The H-atom temporal profiles at long times show only minor sensitivity to the abstraction reaction, H + CH3OC(O)OCH3 → H2 + CH3OC(O)OCH2 [B]. However, H + DMC is an important fuel destruction reaction at high temperatures. Consequently, measurements of D-atom profiles using D-ARAS allowed unambiguous rate constant measurements for the deuterated analog of reaction B, D + CH3OC(O)OCH3 → HD + CH3OC(O)OCH2 [C]. Reaction C is a surrogate for H + DMC since the theoretically predicted kinetic isotope effect at high temperatures (1000 - 2000K) is close to unity, kC ≈ 1.2 kB. TST calculations employing CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties for reactions B and C are in good agreement with the experimental rate constants. The theoretical rate constants for these bimolecular processes can be represented by modified Arrhenius expressions over the T-range 500-2000 K as, kB(T) = 1.45 × 10(-19)T(2.827) exp(-3398 K/T) cm(3) molecule(-1) s(-1) and kC(T) = 2.94 × 10(-19)T(2.729) exp(-3215 K/T) cm(3) molecule(-1) s(-1).

Active diluents effects of 4-nonylphenoxy-1, 2-dinitrilbenzene on phthalonitrile containing benzoxazine and their copolymerization behaviors

nonylphenoxy-1, 2-dinitrilbenzene (NP-ph), a novel kind of phthalonitrile containing flexible hydrocarbyl chains, has been synthesized. The structures of NP-ph were investigated by Nuclear Magnetic Resonance Spectroscopy ( 1 H-NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Low viscosity NP-ph/phthalonitrile containing benzox- azine (BA-ph) blends were achieved by melt blending BA-ph with various content of NP-ph. Copolymerization behaviors and processability of NP-ph/BA-ph have been investigated by Differential Scanning Calorimetry (DSC) and Dynamic Rhe- ological Analysis. Results indicated that NP-ph/BA-ph blends processability was improved and can be controlled by vary- ing NP-ph contents, processing temperature and time. NP-ph/BA-ph polymers were prepared from the thermal polymerization with short curing time and low curing temperatures without addition of any other curing agents, which dis- played high glass transition temperature (>360°C) and attractive thermal decomposition temperature (>420°C). The out- standing glass transition temperature and desirable thermo-oxidative stabilities, together with good processability and sound process conditions could enable the NP-ph/BA-ph polymers to be further explored in the fields under some practical critical circumstances with requirements of high wears and temperatures.

Synthesis of V, Pt and Pt-V colloidal nanoparticles

Bimetallic platinum-vanadium nanoparticles have been successfully synthesised by high temperature thermal decomposition of metal precursor salts. Vanadium is a highly reactive metal and poses considerable difficulty in synthesising metallic nanoparticles, while platinum has low reactivity where nanoparticles are easily synthesised. The difficulties associated with the reduction of vanadium salt were circumvented by the use of high boiling point solvents and selected surfactants. Co-reduction using platinum precursors compatible with the high temperature processes was required for bimetallic nanoparticle synthesis. The chemical synthesis route described is novel, robust and highly reproducible. Microstructural characterisation of nanoparticles synthesised as described, using transmission electron microscopy, reveals single-crystal particles.

Disposable Attenuated Total Reflection-Infrared Crystals from Silicon Wafer: A Versatile Approach to Surface Infrared Spectroscopy

Attenuated total reflection-infrared (ATR-IR) spectroscopy is increasingly used to characterize solids and liquids as well as (catalytic) chemical conversion. Here we demonstrate that a piece of silicon wafer cut by a dicing machine or cleaved manually can be used as disposable internal reflection element (IRE) without the need for polishing and laborious edge preparation. Technical aspects, fundamental differences, and pros and cons of these novel disposable IREs and commercial IREs are discussed. The use of a crystal (the Si wafer) in a disposable manner enables simultaneous preparation and analysis of substrates and application of ATR spectroscopy in high temperature processes that may lead to irreversible interaction between the crystal and the substrate. As representative application examples, the disposable IREs were used to study high temperature thermal decomposition and chemical changes of polyvinyl alcohol (PVA) in a titania (TiO(2)) matrix and assemblies of 65-450 nm thick polystyrene (PS) films.

Preparation of α-Fe2O3 nanotubes via electrospinning and research on their catalytic properties

In this paper, smooth α-Fe2O3 nanotubes have been successfully synthesized by electrospinning of ferric nitrate–polyvinyl alcohol solution followed by calcination in air. The morphologies and structures of the samples were characterized by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. The catalytic properties were studied by differential thermal analysis and thermogravimetric analysis. The results indicated that the as-prepared α-Fe2O3 nanotubes showed a continuous morphology and an extremely high degree of crystallization. The average inner and outer diameters of the obtained α-Fe2O3 nanotubes were about 60 nm and 100 nm, respectively. The obtained α-Fe2O3 nanotubes were able to lower the temperature of the high-temperature thermal decomposition of ammonium perchlorate, while they had little effect on the crystallographic phase transformation and the low-temperature thermal decomposition.

Experiment and theory on methylformate and methylacetate kinetics at high temperatures: Rate constants for H-atom abstraction and thermal decomposition

The shock tube technique was used to study the high temperature thermal decomposition of methylformate (MF) and methylacetate (MA). The formation of H-atoms was measured behind reflected shock waves by using atomic resonance absorption spectrometry (ARAS). The experiments span a T-range of 1194–1371K at pressures ∼0.5atm. The H-atom profiles were simulated using a detailed chemical kinetic mechanism for MF and MA thermal decomposition. The simulations were used to derive rate constants for sensitive decomposition and H-abstraction reactions in MF and MA. In methylformate, the most sensitive reactions that determine H-atom profiles are: (A)CH3OC(O)H→HCO2+CH3(B)CH3OC(O)H+H→CH3OCO+H2 where H is formed from HCO2→H+CO2. In methylacetate the most sensitive reactions affecting H-atom formation are: (C)CH3OC(O)CH3→CH3+OC(O)CH3(D)CH3OC(O)CH3+H→CH2OC(O)CH3+H2 Minor sensitivity was observed for the energetically higher lying bond fission, (E)CH3OC(O)CH3→CH3+CH3OCO and H-atom abstraction from MA by CH3 through, (F)CH3OC(O)CH3+CH3→CH2OC(O)CH3+CH4(G)CH3OC(O)CH3+CH3→CH3OC(O)CH2+CH4 Unlike MF, where H-atoms are formed instantaneously at high-temperatures from (A), in MA, H-atoms form from the CH3 radicals (through CH3+CH3→C2H4+2H) generated primarily through the C–O bond fission channel (C) with minor contributions from (E). A master equation analysis was performed using CCSD(T)/cc-pv∞z//B3LYP/6-311++G(d,p) energetics and molecular properties for all thermal decomposition processes in MF and MA. The theoretical predictions were found to be in good agreement with the present experimentally derived rate constants for the bond fissions. TST calculations employing CCSD(T)/cc-pv∞z//MP2/aug-cc-pvtz energies and molecular properties for reactions (B) and (D) (the only sensitive abstraction processes in MF and MA) are in good agreement with the experimental rate constants. The theoretically derived rate constants for these processes can be represented by modified Arrhenius expressions for the bond fissions at 0.5atm over the T-range 1000–2000K and for the bimolecular abstractions over the 500–2000K regime. kA(T)=9.79×1068T-15.95exp(-57,434K/T)s-1kB(T)=5.67×10-19T2.50exp(-3188K/T)cm3molecule-1s-1kC(T)=1.42×1084T-19.60exp(-63,608K/T)s-1kD(T)=1.18×10-18T2.58exp(-3714K/T)cm3molecule-1s-1kE(T)=1.90×1082T-19.30exp(-64,724K/T)s-1 Our theoretical predictions for MA+CH3 give over the T-range 500–2000K, kF(T)=2.12×10-25T3.93exp(-4440K/T)cm3molecule-1s-1kG(T)=3.40×10-25T3.88exp(-4149K/T)cm3molecule-1s-1 To our knowledge this is the first study providing experimentally derived rate constant values for the primary bond fission and abstraction reactions in MF and MA.

High Temperature Decomposition of Cerium Precursors To Form Ceria Nanocrystal Libraries for Biological Applications

Nanocrystalline ceria is an interesting inorganic material for biological application that can exhibit antioxidant properties due to facile electron transfer between cerium(III) and cerium(IV). In this work, ceria nanocrystals with uniform and tunable size, surface chemistry, and variable cerium(III) content were formed via the high temperature thermal decomposition of ceria precursors including cerium acetylacetonate hydrate, cerium oleylamine, and cerium nitrate hexahydrate. When combined with organic acid and amine surfactants at temperatures between 260 and 320 °C, these cerium precursors decomposed to yield near-spherical cerium oxide nanocrystals with diameters ranging from 3 to 10 nm. For all shapes of nanocrystals, the smallest primary particle sizes had the most cerium(III) content. Both poly(acrylic acid)–octyl amine as well as oleic acid could be used to transfer the hydrophobic nanocrystals into water; acute in vitro toxicology studies revealed that even at high concentrations (e.g., 10 ppm) 3...