Magnesium Particles Coated with Mesoporous Nanoshells as Sustainable Therapeutic‐Hydrogen Suppliers to Scavenge Continuously Generated Hydroxyl Radicals in Long Term

Sustainable supplementation of massive molecular‐H₂ is considered to be the most effective therapy for long‐term elimination of excessive hydroxyl radicals (·OH) in vivo, but has not been achieved so far. In this work, it is demonstrated that magnesium microparticles (Mg MPs) coated with mesoporous nanoshells can achieve the long‐term and high‐efficient generation of therapeutic hydrogen in physiological condition for ·OH scavenging. The as‐proposed magnesium@mesoporous SiO₂ core–shell microparticles (Mg@p‐SiO₂ MPs) are synthesized by developing a modified Stöber method using acetone as the solvent, and they exhibit shell thickness (d)‐dependent H₂ release behavior due to the barrier effect of nanoshells on both the occurrence of Mg–water reaction and H₂ diffusion. Consequently, they are able to provide vast quantities of H₂ molecules dissolved in body fluid with a rate controlled by d over a long period. A simulation model is established which well explains and further predicts the dependence of H₂ release behavior on d, and the long‐term protection of cells from oxidative damage by Mg@p‐SiO₂ MPs is also experimentally validated. As the H₂ concentration and effective duration in medium can be adjusted by dosage and d, Mg@p‐SiO₂ MPs are promising for accurate H₂ drug delivery in vivo.     

Precise determination of Mg/Fe ratios applicable to terrestrial olivine samples using Raman spectroscopy

The relationship between Mg# [ = 100 Mg/(Mg + Fe) in mol] and the Raman shift was analyzed precisely for olivine [(Mg, Fe)₂SiO₄] samples with Mg# between 100 and 62.8. Two prominent peaks at 826–820 cm⁻¹ (peak 1) and 858–849 cm⁻¹ (peak 2) and three subordinate peaks at 883–881 cm⁻¹ (peak 3), 920–914 cm⁻¹ (peak 4), and 967–951 cm⁻¹ (peak 5) were observed to shift monotonously to lower wavenumbers with decreasing Mg#. The ΔMg#( = Mg#_ref − Mg#) versus Δν(= ν_ref − ν) can be linearly regressed for each peak as ΔMg# = A Δν, where ν is a peak wavenumber of olivine with Mg# ranging from 100 to 62.8, and ν_ref is that of olivine with a reference value of Mg#, namely, Mg#_ref. We set Mg#_ref as 100 (i.e.pure forsterite Mg₂SiO₄) whereas A is a regression parameter (5.789, 4.294, 12.34, 6.348, and 2.09, respectively,for peaks 1, 2, 3, 4, and 5). This equation enables us to avoid small inter‐laboratory differences of wavenumber calibration. The equation for peak 2 yields estimations of Mg# in geologically satisfactory precision, ± 1 Mg# (1σ) in the Mg# range of 100–62.8. Copyright © 2011 John Wiley & Sons, Ltd.     

Substituent effects on gas‐phase homolytic Fe–O and Fe–S bond energies of m‐G‐C6H4OFe(CO)2(η5‐C5H5) and m‐G‐C6H4SFe(CO)2(η5‐C5H5) studied using Hartree–Fock and density functional theory methods

The thermochemistry of organometallic complexes in solution and in the gas phase has been an area of increasing research interest. In this paper, the Fe–O and Fe–S homolytic bond dissociation energies [ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s] of two series of meta‐substituted phenoxydicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄OFp ( 1 )] and (meta‐substituted benzenethiolato)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄SFp ( 2 )] were studied using Hartree–Fock and density functional theory methods with large basis sets. In this study, Fp is (η⁵‐C₅H₅)Fe(CO)₂, and G are NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂. The results show that Tao–Perdew–Staroverov–Scuseria and Minnesota 2006 functionals can provide the best price/performance ratio and accurate predictions of ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s. The polar effects of the meta substituents show that the dominant role to the magnitudes of ΔΔH_homo(Fe–O)'s or ΔΔH_homo(Fe–S)'s. σ_α·, σ_c· values for meta substituents are all related to polar effects. Spin‐delocalization effects of the meta substituents in ΔΔH_homo(Fe–O)'s and ΔΔH_homo(Fe–S)'s are small but not necessarily zero. Molecular effects rather than ΔΔH_homo(Fe–O)'s and ΔΔH_homo(Fe–S)'s are more suitable indexes for the overall substituent effects on ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s. The meta substituent effects of meta‐electron‐withdrawing groups on the Fe–S bonds are much stronger than those on the Fe–O bonds. For meta‐electron‐donating groups, the meta substituent effects have the comparable magnitudes between series 1 and 2 . ΔΔH_homo(Fe–O)'s ( 1 ) and ΔΔH_homo(Fe–S)'s ( 2 ) conform to the captodative principle. Insight from this work may help the design of more effective catalytic processes. Copyright © 2015 John Wiley & Sons, Ltd.     

Interference phenomena of synchrotron radiation in TEY spectra for silicon‐on‐insulator structure

The general matrix theory of the photoelectron/fluorescence excitation in anisotropic multilayer films at the total reflection condition of X‐rays has been developed. In a particular case the theory has been applied to explain the oscillation structure of L_2,3 XANES spectra for a SiO₂/Si/SiO₂/c‐Si sample in the pre‐edge region which has been observed by a sample current technique at glancing angles of synchrotron radiation. Remarkably the phase of the oscillations is reversed by a ～2° angle variation. The observed spectral features are found to be a consequence of waveguide mode creation in the middle layer of strained Si, which changes the radiation field amplitude in the top SiO₂ layer. The fit of the data required the correction of the optical constants for Si and SiO₂ near the Si L_2,3‐edges.     

A Raman spectroscopic study of humite minerals

Raman spectroscopy has been used to study the structure of the humite mineral group ((A₂SiO₄)_n–A(OH, F)₂ where n represents the number of olivine and brucite layers in the structure and is 1, 2, 3 or 4 and A²⁺ is Mg, Mn, Fe or some mix of these cations). The humite group of minerals forms a morphotropic series with the minerals olivine and brucite. The members of the humite group contain layers of the olivine structure that alternate with layers of the brucite‐like sheets. The minerals are characterized by a complex set of bands in the 800–1000 cm⁻¹ region attributed to the stretching vibrations of the olivine (SiO₄)⁴⁻ units. The number of bands in this region is influenced by the number of olivine layers. Characteristic bending modes of the (SiO₄)⁴⁻ units are observed in the 500–650 cm⁻¹ region. The brucite sheets are characterized by the OH stretching vibrations in the 3475–3625 cm⁻¹ wavenumber region. The position of the OH stretching vibrations is determined by the strength of the hydrogen bond formed between the brucite‐like OH units and the olivine silica layer. The number of olivine sheets and not the chemical composition determines the strength of the hydrogen bonds. Copyright © 2006 John Wiley & Sons, Ltd.     

Hartree–Fock and density functional theory study of remote substituent effects on gas‐phase heterolytic Fe–O and Fe–S bond energies of p‐G‐C6H4OFe(CO)2(η5‐C5H5) and p‐G‐C6H4SFe(CO)2(η5‐C5H5)

The knowledge of accurate bond strengths is a fundamental basis for a proper analysis of chemical reaction mechanisms. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe–O and Fe–S bond energies of para‐substituted phenoxydicarbonyl(η⁵‐cyclopentadienyl) iron [p‐G‐C₆H₄O(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄OFp ( 1 ), where G = NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂] and para‐substituted benzenethiolatodicarbonyl(η⁵‐cyclopentadienyl) iron [p‐G‐C₆H₄S(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄SFp ( 2 )] complexes. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of ΔH_het(Fe–O)'s and ΔH_het(Fe–S)'s. The excellent linear free‐energy relations [r = 0.99 (g, 1a), 1.00 (g, 2b)] among the ΔΔH_het (Fe–O)'s and Δpk_a's of O–H bonds of p‐G‐C₆H₄OH or ΔΔH_het(Fe‐S)'s and Δpk_a's of S–H bonds of p‐G‐C₆H₄SH imply that the governing structural factors for these bond scissions are similar. And the linear correlations [r = ?0.99 (g, 1g), ?0.98 (g, 2h)] among the ΔΔH_het (Fe‐O)'s or ΔΔH_het(Fe‐S)'s and the substituent σ_p^? constants show that these correlations are in accordance with Hammett linear free‐energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of ΔH_het(Fe–O)'s or ΔH_het(Fe–S)'s. ΔΔH_het(Fe–O)'s(g) ( 1 ) and ΔΔH_het(Fe–S)'s(g)( 2 ) follow the Capto‐dative principle. The substituent effects on the Fe–O bonds are much stronger than those on the less polar Fe–S bonds. Insight from this work may help the design of more effective catalytic processes. Copyright © 2013 John Wiley & Sons, Ltd.     

Minerals from Macedonia. XXII. Laser‐induced fluorescence bands in the FT‐Raman spectrum of almandine mineral

Two strong bands centered at 446 and 607 cm⁻¹ have been observed in the FT‐Raman spectrum of almandine [Fe₃Al₂(SiO₄)₃] excited with 1064 nm, which were completely absent in the corresponding dispersive Raman spectra obtained using 488, 514.5 and 532 nm excitation. Furthermore, the mentioned strong bands have not been registered in the anti‐Stokes side of the FT‐Raman spectrum, and were therefore assigned to laser‐induced fluorescence bands. Their appearance is related to the presence of rare‐earth element traces as impurities in the almandine sample. Additionally, the FT‐Raman (and dispersive Raman) spectrum of the isomorphous spessartine [Mn₃Al₂(SiO₄)₃] mineral has been introduced, which did not show the presence of these fluorescence emission bands. The purity of the minerals was confirmed by study of their powder X‐ray diffraction (PXRD) patterns. Copyright © 2008 John Wiley & Sons, Ltd.     

Substituent effects on gas‐phase homolytic Fe–N bond energies of m‐G‐C6H4NHFe(CO)2(η5‐C5H5) and m‐G‐C6H4N(COMe)Fe(CO)2(η5‐C5H5) studied using density functional theory methods

One of the most fundamental properties in chemistry is the bond dissociation energy, the energy required to break a specific bond of a molecule. In this paper, the Fe–N homolytic bond dissociation energies [ΔH_homo(Fe–N)'s] of 2 series of (meta‐substituted anilinyl)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄NHFp ( 1 )] and (meta‐substituted α‐acetylanilinyl)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄N(COMe)Fp ( 2 )] were studied using density functional theory methods with large basis sets. In this study, Fp is (η⁵‐C₅H₅)Fe(CO)₂, and G is NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂. The results show that Tao‐Perdew‐Staroverov‐Scuseria, Minnesota 2006, and Becke's power‐series ansatz from 1997 with dispersion corrections functionals can provide the best price/performance ratio and accurate predictions of ΔH_homo(Fe–N)'s. The ΔΔH_homo(Fe–N)'s ( 1 and 2 ) conform to the captodative principle. The polar effects of the meta‐substituents show the dominant role to the magnitudes of ΔΔH_homo(Fe–N)'s. σ_α· and σ_c· values for meta‐substituents are all related to polar effects. Spin‐delocalization effects of the meta‐substituents in ΔΔH_homo(Fe–N)'s are small but not necessarily zero. RE plays an important role in determining the net substituent effects on ΔH_homo(Fe–N)'s. Insight from this work may help the design of more effective catalytic processes.     

Density functional theory study of substituent effects on gas‐phase heterolytic Fe–O and Fe–S bond energies of m‐G‐C6H4OFe(CO)2(η5‐C5H5) and m‐G‐C6H4SFe(CO)2(η5‐C5H5)

The knowledge of accurate bond strengths is a fundamental basis for a proper analysis of chemical reaction mechanisms. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe–O and Fe–S bond energies of (meta‐substituted phenoxy)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄OFp ( 1 )] and (meta‐substituted benzenethiolato)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄SFp ( 2 )] complexes. In this study, Fp is (η⁵‐C₅H₅)Fe(CO)₂, and G is NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂. The results show that Tao–Perdew–Staroverov–Scuseria and Becke's power‐series ansatz from 1997 with dispersion corrections functionals can provide the best price/performance ratio and accurate predictions of ΔH_het(Fe–O)'s and ΔH_het(Fe–S)'s. The excellent linear free energy relations [r = 1.00 (g, 1e), 1.00 (g, 2b)] among the ΔΔH_het (Fe–O)'s and δΔG⁰ of O?H bonds of m‐G‐C₆H₄OH or ΔΔH_het(Fe–S)'s and ΔpK_a's of S?H bonds of m‐G‐C₆H₄SH imply that the governing structural factors for these bond scissions are similar. And, the linear correlations [r = ?0.97 (g, 1 g), ?0.97 (g, 2 h)] among the ΔΔH_het (Fe–O)'s or ΔΔH_het(Fe–S)'s and the substituent σ_m constants show that these correlations are in accordance with Hammett linear free energy relationships. The inductive effects of these substituents and the basis set effects influence the accuracy of ΔH_het(Fe–O)'s or ΔH_het(Fe–S)'s. The ΔΔH_het(Fe–O)'s(g) (1) and ΔΔH_het(Fe–S)'s(g)(2) follow the capto‐dative Principle. The substituent effects on the Fe–O bonds are much stronger than those on the less polar Fe–S bonds. Insight from this work may help the design of more effective catalytic processes. Copyright © 2016 John Wiley & Sons, Ltd.     

Magnetic Properties of Fe/Ni and Fe/Co Multilayer Thin Films

In this work, the magnetic and transport properties of Fe/SiO₂/Ni and Fe/SiO₂/Co multilayers grown on Si/SiO₂ substrates have been studied. The samples have been prepared by two-stage deposition process. In the first stage, Fe layer and SiO₂ interlayer of both samples are grown by ion beam deposition technique at room temperature. Then the samples are taken out to ambient atmosphere and loaded into a pulse laser deposition (PLD) chamber. Prior to the deposition of top layer, the samples are cleaned by annealing at 150 °C. In the second stage, Ni (or Co) layer is prepared by PLD technique at room temperature. The thickness of deposited layers has been measured by Rutherford back scattering (RBS). Magnetic properties of ferromagnetic bilayers have been investigated by room-temperature ferromagnetic resonance (FMR) and vibrating sample magnetometer (VSM) techniques. Standard four-point magneto-transport measurements at various temperatures have been performed. Two-step switching in the in-plane hysteresis loops of Fe/SiO₂/Ni and Fe/SiO₂/Co samples is observed. A crossing in the middle of hysteresis loops of both samples points to a weak antiferromagnetic interaction between the magnetic layers of the stacks. Saturation magnetization values have been obtained from the VSM measurements of samples with DC magnetic field perpendicular to the films surface. Magneto-transport measurements have shown the predominant contribution of anisotropic magnetic resistance both at room and low temperatures. FMR studies of Fe/SiO₂/Ni and Fe/SiO₂/Co samples have revealed additional non-uniform (surface and bulk SWR) modes, which behavior has been explained in the framework of the surface inhomogeneity model. An origin of the antiferromagnetic interaction has been discussed.     

In‐Situ Determination of the Charging of Nanometer and Submicron Particles at High Temperatures

Thermal charging of submicron and nanometer particles has been studied for model aerosols of TiO₂ and SiO₂ as well as Al‐Si (aluminosilicate) at 1 000 °C with a new quasi in‐situ technique. The size dependence of the particle separation efficiency for electrostatic precipitation was determined. The charging state of the particles was obtained from evaluating the global Deutsch number for precipitation in an electric field applied to a laminar flow based on particle trajectory considerations.     

Assessment of the illumination dependency of Al2O3 and SiO2 rear‐passivated p‐type silicon solar cells

This Letter discusses an important difference between positively charged SiO₂ and negatively charged Al₂O₃ rear‐passivated p‐type Si solar cells: their illumination level dependency. For positively charged SiO₂ rear‐passivated p‐type Si solar cells, a loss in short circuit current (J_SC) and open circuit voltage (V_OC) as a function of illumination level is mainly caused by parasitic shunting and a decrease in surface recombination, respectively. Hence, the relative loss in cell conversion efficiency, J_SC, and V_OC as a function of the illumination level for SiO₂ compared to Al₂O₃ rear‐passivated p‐type Si solar cells has been measured and discussed. Subsequently, an exponential decay fit of the loss in cell efficiency is applied in order to estimate the difference in the energy output for both cell types in three different territories: Belgium (EU), Seattle and Austin (US). The observed trends in the difference in energy output between both cells, as a function of time of the year and region, are as expected and discussed. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Remote substituent effects on gas‐phase homolytic Fe–O and Fe–S bond energies of p‐G‐C6H4OFe(CO)2(η5‐C5H5) and p‐G‐C6H4SFe(CO)2(η5‐C5H5) studied using Hartree–Fock and density functional theory methods

Metal–ligand bond enthalpy data can afford invaluable insights into important reaction patterns in organometallic chemistry and catalysis. In this paper, the Fe–O and Fe–S homolytic bond dissociation energies [ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s] of two series of para‐substituted phenoxydicarbonyl(η⁵‐cyclopentadienyl) iron [p‐G‐C₆H₄OFp ( 1 )] and (para‐substituted benzenethiolato)dicarbonyl(η⁵‐cyclopentadienyl) iron [p‐G‐C₆H₄SFp ( 2 )] were studied using Hartree–Fock and density functional theory (DFT) methods with large basis sets. In this study, Fp is (η⁵‐C₅H₅)Fe(CO)₂, and G are NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂. The results show that DFT methods can provide the best price/performance ratio and accurate predictions of ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s. The remote substituent effects on ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s [ΔΔH_homo(Fe–O)'s and ΔΔH_homo(Fe–S)'s] can also be satisfactorily predicted. The good correlations [r = 0.98 (g, 1), 0.98 (g, 2)] of ΔΔH_homo(Fe–O)'s and ΔΔH_homo(Fe–S)'s in series 1 and 2 with the substituent σ_p⁺ constants imply that the para‐substituent effects on ΔH_homo(Fe–O)'s and ΔH_homo(Fe–S)'s originate mainly from polar effects, but those on radical stability originate from both spin delocalization and polar effects. ΔΔH_homo(Fe–O)'s ( 1 ) and ΔΔH_homo(Fe–S)'s ( 2 ) conform to the captodative principle. Insight from this work may help the design of more effective catalytic processes. Copyright © 2013 John Wiley & Sons, Ltd.     

Hartree–Fock and density functional theory study of remote substituent effects on heterolytic Fe–N bond energies of p‐G‐C6H4NHFe(CO)2(η5‐C5H5) and p‐G‐C6H4N(COMe)Fe(CO)2(η5‐C5H5)

The nature and strength of metal–ligand bonds in organotransition‐metal complexes are crucial to the understanding of organometallic reactions and catalysis. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe–N bond energies of para‐substituted anilinyldicarbonyl(η⁵‐cyclopentadienyl)iron [p‐G‐C₆H₄NH(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄NHFp (1), where G = NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂] and para‐substituted α‐acetylanilinyldicarbonyl(η⁵‐cyclopentadienyl)iron [p‐G‐C₆H₄N(COMe)(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄N(COMe)Fp (2)] complexes. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of ΔH_het(Fe–N)'s. The linear correlations [r = 0.98 (g, 1a), 0.93 (g, 2b)] between the substituent effects of heterolytic Fe–N bond energies [ΔΔH_het(Fe–N)'s] of series 1 and 2 and the differences of acidic dissociation constants (ΔpK_a) of N–H bonds of p‐G‐C₆H₄NH₂ and p‐G‐C₆H₄NH(COMe) imply that the governing structural factors for these bond scissions are similar. And the linear correlations [r = ?0.99 (g, 1c), ?0.92 (g, 2d)] between ΔΔH_het(Fe–N)'s and the substituent σ_p^? constants show that these correlations are in accordance with Hammett linear free energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of ΔH_het(Fe–N)'s. ΔΔH_het(Fe–N)'s(1, 2) follow the captodative principle. ME_{α‐COMe, para‐G}s include the influences of the whole molecules. The correlation of ME_{α‐COMe, para‐G}s with σ_p^? is excellent. ME_{α‐COMe, para‐G}s rather than ΔΔH_het(Fe–N)'s in series 2 are more suitable indexes for the overall substituent effects on ΔH_het(Fe–N)'s(2). Insight from this work may help the design of more effective catalytic processes. Copyright © 2012 John Wiley & Sons, Ltd.     

Hartree–Fock and density functional theory study of remote substituent effects on heterolytic Fe―C bond energies of p‐G‐C6H4CH2Fe(CO)2(η5‐C5H5) and p‐G‐C6H4(H)(CN)CFe(CO)2(η5‐C5H5)

Knowledge of the strength of the metal–ligand bond breaking and formation is fundamental for an understanding of the thermodynamics underlying many important stoichiometric and catalytic organometallic reactions. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe―C bond energies of para‐substituted benzyldicarbonyl(η⁵‐cyclopentadienyl)iron, p‐G‐C₆H₄CH₂Fp [1, G = NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, NMe₂; Fp = (η⁵‐C₅H₅)(CO)₂Fe], and para‐substituted α‐cyanobenzyldicarbonyl(η⁵‐cyclopentadienyl)iron, p‐G‐PANFp [2, PAN = C₆H₄CH(CN)]. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of ΔH_het(Fe―C)'s. The good linear correlations [r = 0.98 (g, 1a), 0.99 (g, 2b)] between the substituent effects of heterolytic Fe―C bond energies [ΔΔH_het(Fe―C)'s] of series 1 and 2 and the differences of acidic dissociation constants (ΔpK_a) of C―H bonds of p‐G‐C₆H₄CH₃ and p‐G‐C₆H₄CH₂CN imply that the governing structural factors for these bond scissions are similar. And the excellent linear correlations [r = ?1.00 (g, 1c), ?0.99 (g, 2d)] between ΔΔH_het(Fe―C)'s and the substituent σ_p^? constants show that these correlations are in accordance with Hammett linear free energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of ΔH_het(Fe―C)'s. ΔΔH_het(Fe―C)'s(1, 2) follow the Capto‐dative Principle. The detailed knowledge of the factors that determine the Fp―C bond strengths would greatly aid in understanding reactivity patterns in many processes. Copyright © 2011 John Wiley & Sons, Ltd.     

Depth of generation of X-ray characteristic emission bands in solid targets

The factors responsible for the poor agreement between the experimental data on the depth of the generation of the Si L _2,3 X-ray emission band excited by an electron impact in SiO₂ layers and the results of the calculations performed in terms of the Borovskii-Rydnik phenomenological model modified for nonisotropic and nanostructured systems have been analyzed. It has been demonstrated that the most probable factor accounting for the disagreement is the effect of the roughness of the surface and interface of the SiO₂/Si system under investigation in the range of low energies of primary electrons and a decrease in the sensitivity and the accuracy in the measurements in the range of large thicknesses and high energies. Since no errors have been revealed in the calculation model used, it has been employed to calculate the dependence of the depth of generation of the L X-ray emission bands in Mg, Si, Ti, Cr, Fe, and Cu crystals on the energy of electrons of the primary electron beam.     

SiOx precipitate composition in Si,revisited: Discussion closed?

The composition SiO_x of oxide precipitates in Si has been discussed for the past thirty years with experimentally estimated x ‐values ranging between 1 and 2. It is shown that this spread of x ‐values can be explained by calculating the average composition taking into account temperature and anneal time dependent size and shape of the precipitates and the limitations and probing volumes of the various characterization techniques. Hereby it is assumed that the oxygen‐rich (SiO₂?) core of the precipitates is surrounded by a 2 nm thin SiO layer as revealed by recent electron energy loss spectroscopy analyses. For plate‐like precipitates thinner than and for octahedral precipitates smaller than 6 nm, x ≈ 1. For larger precipitates, the central part of the precipitate consists of SiO_x with x close to 2 and the precipitate has an average x between 1 and 1.3 for plate‐like and up to 1.9 for octahedral precipitates. The predicted x ‐values for different precipitate sizes and morphologies, are compared with published experimental data. SiO_x precipitate nucleation and initial growth should be simulated assuming x = 1 and Fourier transform infrared spectra of precipitates assuming a mixture of SiO₂ and amorphous Si. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

After effects of ec decay of57Co in Mg(1-x)FexSO4.7H2O mixed crystals

After effects due to the EC decay of⁵⁷Co in the mixed crystals (Mg,Fe)SO₄·7H₂O were studied. When the Fe concentrationx=Fe/(Fe+Mg) is 0.4≈0.5, the surroundings of⁵⁷Fe have the characteristics of orthorhombic MgSO₄·7H₂O although the crystal structure is monoclinic. This fact suggests a possibility of transient release of the Jahn-Teller transformation.     

A Study on the Components of MgB2 Thick Film Preparedvia HPCVD

Superconducting MgB₂ thick film has been prepared via hybrid physical-chemical vapor deposition method on Al₂O₃ (0001) substrate by using B₂H₆ and magnesium ingot as raw materials reacted from 730 to 830°C for 40 min under 20 to 30 kPa. Its thickness is about 40 μm. The MgB₂ thick film shows T _c (onset) = 39.0 K and T _c (0) = 37.2 K. X-ray diffraction pattern shows that the film grown along (101) direction has small amount of impurities of Mg and MgO. Scanning electron microscopy and energy dispersive X-ray spectroscopy indicated that these impurities existed indeed and were Mg rich. The MgO film was formed on the surface of the MgB₂ thick film to further protect the sample from oxidation. We presented a new mechanism for the formation of the thick film. Translated from Chinese Journal of Low Temperature Physics, 2005, 27(1) (in Chinese)