Spatial distribution pattern and correlation of dominant species in the arbor layer at a 25 hm forest plot in Lushan Mountain, China.

To explore the spatial pattern of zonal tree species in the subtropical subalpine mountain area on Lushan Mountain, a 25 hm forest plot was established in Yangtianping area of Lushan Mountain following the technical specification of CTFS in 2021. We classified these species into evergreen conifer species, deciduous broad-leaved species and evergreen broad-leaved species based on their leaf shape and deciduous or not to analyze the spatial pattern of dominant species of different types by spatial point pattern method. The results showed that , subsp.

Regioselective conversions of Hpdta (1,2-propanediaminetetraacetic acid) and Heed3a to their triacetates on peroxotitanates.

1,2-Propanediaminetetraacetic acid (Hpdta = CHON) is degraded selectively to 1-methyl-1,2-propanediaminetriacetic acid (Hpd3a = CHON) with a yield of 75% at room temperature, while N-(2-hydroxyethyl) ethylenediaminetriacetic acid (Heed3a = CHON) is converted with difficulty to ethylenediaminetriacetic acid (Hed3a = CHON) on peroxotitanates(iv), showing the influence of the uncoordinated leaving group. Various species in the reaction sequence are isolated and fully characterized, including (NH)[Ti(O)(Hpdta)]·HO (1), (NH)[Ti(O)(pdta)H(pdta)(O)Ti]·7HO (2), (NH)[Ti(O)(pd3a)]·HO (3) and (NH)[Ti(O)(Heed3a)]·HO (5). Peroxo dimer 2 forms a strong intramolecular hydrogen bond [2.

Photoinduced Formation of Peroxide Ions on La2O3 and Nd2O3 under O2: Effects of Excitation Wavelength and Crystal Structure.

Photoinduced formation of peroxide ions on La2O3 and Nd2O3 under O2 was studied by in-situ microprobe Raman spectroscopy with attention focused on the effect of excitation wavelength and crystal structure on the O2(2-) formation. It was found that photoexcitations at 633, 532, 514, and 325 nm can induce O2(2-) formation over La2O3 at 450 °C. By contrast, photoexcitation at 785 nm does not cause formation of O2(2-) up to 500 °C.

Dimeric 1,3-propanediaminetetraacetato lanthanides as the precursors of catalysts for the oxidative coupling of methane.

From neutral solutions, dimeric 1,3-propanediaminetetraacetato lanthanides (NH4)2[Ln2(1,3-pdta)2(H2O)4]·8H2O [Ln = La, 1; Ce, 2] and K2[Ln2(1,3-pdta)2(H2O)4]·11H2O [Ln = La, 3; Ce, 4] (1,3-H4pdta = 1,3-propanediaminetetraacetic acid, C11H18N2O8) were isolated in high yields. The reaction of excess strontium nitrate with 1 resulted in the formation of a two dimensional coordination polymer [La2(1,3-pdta)2(H2O)4]n·[Sr2(H2O)6]n·[La2(1,3-pdta)2(H2O)2]n·18nH2O (5) at 70 °C. Complexes 1-4 show a similar central molecular structure.

Effect of calcination temperature and pretreatment with reaction gas on properties of Co/γ-Al2O3 catalysts for partial oxidation of methane.

The effects of calcination temperature and feedstock pretreatment on the catalytic performance of Co/γ-Al(2)O(3) catalysts were studied for partial oxidation of methane (POM) to synthesis gas, with emphasis on the role of feedstock pretreatment. The physicochemical properties of the catalysts were characterized by N(2) adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), H(2) temperature-programmed reduction (H(2) -TPR), and Raman spectroscopy. The results showed that the pretreatment of the catalyst by reaction gas significantly improved the catalytic activity and stability for the POM reaction.

Mechanistic aspects of photo-induced formation of peroxide ions on the surface of cubic Ln2O3 (Ln = Nd, Sm, Gd) under oxygen.

The photo-induced formation of peroxide ions on the surface of cubic Ln2O3 (Ln = Nd, Sm, Gd) was studied by in situ microprobe Raman spectroscopy using a 325 nm laser as excitation source. It was found that the Raman bands of peroxide ions at 833-843 cm(-1) began to grow at the expense of the Ln(3+)-O(2-) bands at 333-359 cm(-1) when the Ln2O3 samples under O2 were continuously irradiated with a focused 325 nm laser beam at temperatures between 25-150 °C. The intensity of the peroxide Raman band was found to increase with increasing O2 partial pressure, whereas no peroxide band was detected on the Ln2O3 under N2 as well as on the samples first irradiated with laser under Ar or N2 followed by exposure to O2 in the dark.

In situ Raman and pulse reaction study on the partial oxidation of methane to synthesis gas over a Pt/Al2O3 catalyst.

Catalytic partial oxidation of methane (POM) to synthesis gas (syngas) over Pt/Al(2)O(3) was investigated by in situ microprobe Raman and pulse reaction methods with attention focused on the mechanism of syngas formation in the oxidation zone (i.e., the catalyst zone in which O(2) was still available in the reaction feed).

Brønsted-NH(4)(+) mechanism versus nitrite mechanism: new insight into the selective catalytic reduction of NO by NH(3).

The selective catalytic reduction (SCR) of NO by NH(3) over V(2)O(5)-based catalysts is used worldwide to control NO(x) emission. Understanding the mechanisms involved is vital for the rational design of more effective catalysts. Here, we have performed a systematic density functional theory (DFT) study of a SCR reaction by using cluster models.

Mechanisms for O2 dissociation over the BaO (100) surface.

We have investigated the atomic and molecular oxygen adsorptions on the various sites of the BaO (100) surface with both cluster models and the periodic slab models. We found that the atomic oxygen prefers to adsorb on the surface O2- to form the closed-shell peroxides with the binding energies of 83-88 kcal/mol. Such a high exothermicity provides a large driving force for the dissociation of molecular O2 on the BaO surfaces.

Understanding the reactivity of the tetrahedrally coordinated high-valence d0 transition metal oxides toward the C-H bond activation of alkanes: a cluster model study.

We have carried out a theoretical study on the structure-function relationship for the selective oxidation of lower alkanes (C1-C4). The H abstraction mechanism has been examined over the model catalysts of high-valence d0 transition metal oxides in the tetrahedral coordination. The intrinsic connections among the H abstraction barrier, the strengths of the O-H and the M-O bonds, the ability of electron transfer, as well as the energy gap of frontier orbitals of the oxides have been rationalized in terms of thermodynamics cycles and the frontier orbital analysis.

pH-dependent isolations and spectroscopic, structural, and thermal studies of titanium citrate complexes.

Titanium(IV) citrate complexes (NH(4))(2)[Ti(H(2)cit)(3)].3H(2)O (1), (NH(4))(5)[Fe(H(2)O)(6)][Ti(H(2)cit)(3)(Hcit)(3)Ti].3H(2)O (2), Ba(2)[Ti(H(2)cit)(Hcit)(2)].

Peroxomolybdate(VI)-citrate and -malate complex interconversions by pH-dependence. Synthetic, structural and spectroscopic studies.

The reaction of potassium molybdate(VI) with biologically relevant ligands, citric and malic acids, in the presence of H2O2 was investigated for the effect of pH variations on the product pattern. That with citric acid led to the formation of the monomeric complex K4[MoO(O2)2(cit)].4H2O (1) in the pH range 7-9, and dimer K5[MoO(O2)(2-)(Hcit)H(Hcit)(O2)2OMo].

Syntheses, crystal structures and biological relevance of glycolato and S-lactato molybdates.

Glycolato and S-lactato complexes containing the dioxomolybdenum(VI) moiety have been synthesized for studies on the role of the alpha-hydroxycarboxylato anion in the iron molybdenum cofactor of nitrogenase. The ligands in these complexes, vis K2[MoO2(glyc)2].H2O (H2glyc=glycolic acid, C2H4O3) (1) and (Na2[MoO2(S-lact)2])3.

Synthesis and characterization of homochiral polymeric S-malato molybdate(VI): toward the potentially stereospecific formation and absolute configuration of iron-molybdenum cofactor in nitrogenase.

Reaction of sodium or potassium molybdate and excess malic acid in a wide range of pH values (pH 4.0-7.0) resulted in the isolation of two cis-dioxo-bis(malato)-Mo(VI) complexes, viz.

Mechanistic study of partial oxidation of methane to syngas using in situ time-resolved FTIR and microprobe Raman spectroscopies.

In situ time-resolved Fourier transform infrared (FTIR) and microprobe Raman spectroscopies were used to characterize the reaction mechanisms of the partial oxidation of methane to syngas over SiO(2)- and gamma-Al(2)O(3)-supported rhodium and ruthenium catalysts. The interaction of both pure methane and a methane/oxygen mixture at a stoichiometric feed ratio with an oxygen-rich catalyst surface led to the formation of CO2 and H(2)O as the primary products. For the H(2)-pretreated samples, the reaction mechanisms with the catalysts differ.