Analysis of variance and linear contrasts in experimental design with generalized secant hyperbolic distribution

We consider one-way classification model in experimental design when the errors have generalized secant hyperbolic distribution. We obtain efficient and robust estimators for block effects by using the modified maximum likelihood estimation (MML) methodology. A test statistic analogous to the normal-theory F statistic is defined to test block effects. We also define a test statistic for testing linear contrasts. It is shown that test statistics based on MML estimators are efficient and robust. The methodology readily extends to unbalanced designs.     

Experimental and modeling assessment of sulfur release from coal under low and high heating rates

Coal combustion releases elevated amounts of pollutants to the atmosphere including SO_X. During the pyrolysis step, sulfur present in the coal is released to the gas phase as many different chemical species such as H₂S, COS, SO₂, CS₂, thiols and larger tars, also called SO_X precursors, as they form SO_X during combustion. Understanding the sulfur release process is crucial to the development of reliable kinetic models, which support the design of improved reactors for cleaner coal conversion processes. Sulfur release from two bituminous coals, Colombian hard coal (K1) and American high sulfur coal (U2), were studied in the present work. Low heating rate (LHR) experiments were performed in a thermogravimetric analyzer coupled with mass spectrometry (TG-MS), allowing to track the mass loss and the evolution of many volatile species (CO, CO₂, CH₄, SO₂, H₂S, COS, HCl and H₂O). High heating rate (HHR) experiments were performed in an entrained flow reactor (drop-tube reactor – DTR), coupled with MS and nondispersive infrared sensor (NDIR). HHR experiments were complemented with CFD simulation of the multidimentional reacting flow field. A kinetic model of coal pyrolysis is employed to reproduce the experiments allowing a comprehensive assessment of the process. The suitability of this model is confirmed for LHR. The combination of HHR experiments with CFD simulations and kinetic modeling revealed the complexity of sulfur chemistry in coal combustion and allowed to better understand of the individual phenomena resulting in the formation of the different SO_X precursors. LHR and HHR operating conditions lead to different distribution of sulfur species released, highly-dependent on the gas-phase temperature and residence time. Higher retention of total sulfur in char is observed at LHR (63%) when compared to HHR (37–44%), at 1273 K. These data support the development of reliable models with improved predictability.     

A facile preparation of donut-like supramolecular tannic acid-Fe(III) composite as biomaterials with magnetic,conductive, and antioxidant properties

Tannic acid (TA) complexes with various metal ions are prepared in buffer solutions by readily adjusting the pH, but there is no normalizing method to produce ferric tannate complexes. In this study, TA-Fe(III) complex was prepared in reverse microemulsion medium by reaction of TA as ligand with Fe(III) in 1:3 ligand:metal ion molar ratio. The complex was characterized by SEM, AFM, FT-IR, elemental analysis, AAS measurement, and Brunauer-Emmett-Teller (BET) method. Furthermore, magnetic susceptibility was tested with the Gouy method, and electronic spectral studies of TA-Fe(III) complex were completed with solid UV–vis measurements. The thermal stability was also studied by TGA analysis. These studies show that the ligand molecules have octahedral arrangement around Fe(III) and the complex is paramagnetic. The bandgap energy of the complex was calculated as 3.42 eV with solid UV–vis analysis. To determine antioxidant activity of the complex, Total Phenol Content (TPC) and Trolox Equivalent Antioxidant Concentration (TEAC) methods were used. The complex has great antioxidant properties with TPC = 45 ± 1 mg L^?1 GAE and TEAC = 296 ± 2 mM trolox g^?1 for dry sample.     

含黄酮的三价铁配合物合成及其药理性质(英文)

3,3,4,7-四羟基黄酮与1,3-二环己基碳二亚胺在4-二甲胺吡啶存在下反应,得到2,2-双(3,3,4,7-四羟基黄酮)1,3-二环己基碳二亚胺。三价金属离子与上述合成得到的配体螯合,对此四面体结构的双核Fe(Ⅲ)配合物的血液学及病理学数据进行了讨论,同时研究了合成的配体作为螯合剂清除鼠肝胰组织中超载的铁的能力。结果表明作为口服药其作为双齿配体的螯合能力与市售用于治疗地中海贫血的药物"去铁敏"相近。     

Solvent,substituent, and dimerization effects on the ring-opening mechanisms of monosilacyclopropylidenoids: a theoretical study

Density functional theory and ab initio computations elucidated the ring-opening of substituted (R = –CF₃, –CN, –CH₃, –H, –NH₂, –OCH₃, –OH, –SiH₃) 1-bromo–1-lithiosilirane 1 and 2-bromo–2-lithiosilirane 2 to LiBr complexes of 2-silaallene and 1-silaallene, respectively. Formally, two competitive pathways can be considered. The ring-opening reaction can take place through a concerted manner via TS3. Alternatively, the reaction may proceed in a stepwise fashion with the intermediacy of a free silacyclopropylidene–LiBr complex 7. In both cases, the position of the substituents determines the kinetic of the reactions. The structures with an electron-donating group are generally unstable, whereas the silacyclopropylidenoids bearing electron-withdrawing substituents are particularly stable species. Here, we propose the ring-opening of 5a–h to corresponding LiBr complexes of 2-silaallenes can proceed in both concerted and stepwise mechanism except for –H, –CH₃, and –SiH₃. The obtained activation energies for the ring-openings of 5a–h to related 2-silaallenes are too high for a reaction at room temperature with up to 61.4 kcal/mol. In contrast, the activation energy barriers for the isomerization of 6a–h to the LiBr complexes of 1-silaallenes was determined to be relatively low at the B3LYP/6-31+G(d,p), M06/6-31+G(d,p), and MP2/6-31+G(d,p) levels. Moreover, we have also investigated the solvent effect on the unsubstituted models using both implicit and explicit solvation models. The energy barriers of the solvated models are found to be slightly higher than the results of gas phase calculations. Additionally, the ring-opening of dimer 6 (6–Dim) is also calculated for the ring-opening mechanism with the energy barrier of 3.7 kcal/mol at B3LYP/6-31+G(d,p) level of theory.     

Interstitialcy diffusion of oxygen in tetragonal La2CoO(4+δ)

We report on the mechanism and energy barrier for oxygen diffusion in tetragonal La(2)CoO(4+δ). The first principles-based calculations in the Density Functional Theory (DFT) formalism were performed to precisely describe the dominant migration paths for the interstitial oxygen atom in La(2)CoO(4+δ). Atomistic simulations using molecular dynamics (MD) were performed to quantify the temperature dependent collective diffusivity, and to enable a comparison of the diffusion barriers found from the force field-based simulations to those obtained from the first principles-based calculations. Both techniques consistently predict that oxygen migrates dominantly via an interstitialcy mechanism. The single interstitialcy migration path involves the removal of an apical lattice oxygen atom out from the LaO-plane and placing it into the nearest available interstitial site, whilst the original interstitial replaces the displaced apical oxygen on the LaO-plane. The facile migration of the interstitial oxygen in this path is enabled by the cooperative titling-untilting of the CoO(6) octahedron. DFT calculations indicate that this process has an activation energy significantly lower than that of the direct interstitial site exchange mechanism. For 800-1000 K, the MD diffusivities are consistent with the available experimental data within one order of magnitude. The DFT- and the MD-predictions suggest that the diffusion barrier for the interstitialcy mechanism is within 0.31-0.80 eV. The identified migration path, activation energies and diffusivities, and the associated uncertainties are discussed in the context of the previous experimental and theoretical results from the related Ruddlesden-Popper structures.     

Summary of the CMS potential for the Higgs boson discovery

The European Physical Journal C - This work summarizes the studies for the Higgs boson searches in CMS at the LHC collider. The main discovery channels are presented and the potential is given for...