catena-Poly[[trimethyl­tin(IV)]-μ-2,5-difluoro­benzoato-κ2 O:O′]

In the title polymeric coordination compound, [Sn(CH3)3(C7H3F2O2)]n, the Sn atom exhibits a distorted trigonal-bipyramidal coordination geometry with the carboxyl­ate O atoms in the axial positions and the equatorial positions occupied by the methyl groups. The two Sn—O bond lengths are 2.225 (5) and 2.410 (6) Å

catena-Poly[[trimethyl­tin(IV)]-μ-2,4,6-trichloro­benzoato]

In the title compound, [Sn(CH3)3(C7H2Cl3O2)]n, the tin(IV) atom exhibits a slightly distorted trigonal-bipyramidal geometry with two O atoms of symmetry-related carboxyl­ate groups in the axial positions and three methyl groups in the equatorial positions. In the crystal structure, the metal atoms are linked by carboxyl­ate bridges into polymeric chains extending along the b axis

Tris(O-cyclo­hexyl dithio­carbonato-κS)anti­mony(III)

In the mol­ecule of the title compound, [Sb(C7H11OS2)3], the anti­mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination

Octa­butyl­bis{(E)-2-[4-(2-hydroxy­benzyl­ideneamino)phen­yl]acetato}di-μ2-methoxo-di-μ3-oxido-tetra­tin(IV)

The title compound, [Sn4(C4H9)8(C15H12NO3)2(CH3O)2O2], is a centrosymmetric dimer and displays a ladder type structural motif. There are four SnIV centres which can be divided into two sorts, viz. two endocyclic and two exocyclic. The endo- and exocyclic SnIV centres are linked by bidentate deprotonated methanol and μ3-O atoms. Each exocyclic SnIV centre is also coordinated by a monodentate 2-[4-(2-hydroxy­benzyl­idene­amino)phen­yl]acetate ligand. Parts of the butyl groups were found to be disordered over two sets of sites

3-Eth­oxy-2-(1,3-thia­zol-2-yl)isoindolin-1-one

In the title compound, C13H12N2O2S, the dihedral angles between the isoindolone ring system and the thia­zole ring and the eth­oxy group are 6.50 (11) and 89.0 (2)°, respectively

catena-Poly[[trimethyl­tin(IV)]-μ-2-(3-thien­yl)acetato]

The title compound, [Sn(CH3)3(C6H5O2S)]n, forms an infinite chain structure parallel to [100]. There are two mol­ecules of the complex in the asymmetric unit. The geometry of the Sn atoms in both mol­ecules is distorted trigonal-bipyramidal. The S and C atoms of the thio­phene rings in both mol­ecules are disordered over two sites with site-occupancy factors 0.799 (9)/0.201 (9) and 0.618 (7)/0.382 (7), respectively

Experimental warming causes mismatches in alpine plant-microbe-fauna phenology

Long-term observations have shown that many plants and aboveground animals have changed their phenology patterns due to warmer temperatures over the past decades. However, empirical evidence for phenological shifts in alpine organisms, particularly belowground organisms, is scarce. Here, we investigate how the activities and phenology of plants, soil microbes, and soil fauna will respond to warming in an alpine meadow on the Tibetan Plateau, and whether their potential phenological changes will be synchronized. We experimentally simulate an increase in soil temperature by 2-4 degrees C according to future projections for this region. We find that warming promotes plant growth, soil microbial respiration, and soil fauna feeding by 8%, 57%, and 20%, respectively, but causes dissimilar changes in their phenology during the growing season. Specifically, warming advances soil faunal feeding activity in spring and delays it in autumn, while their peak activity does not change; whereas warming increases the peak activity of plant growth and soil microbial respiration but with only minor shifts in their phenology. Such phenological asynchrony in alpine organisms may alter ecosystem functioning and stability.Phenological shifts driven by climate change are well-studied in plants and aboveground animals, but scarcely in belowground biota. Here, the authors show that soil warming causes phenological mismatches between plants, soil microbes and soil microarthropods in an alpine meadow

Static and flow behaviors of supercritical CO

Aiming at improving the stability of Supercritical CO2 (SC-CO2) foam in high temperature and salinity reservoirs, a kind of betaine surfactant, Hexadecyl Hydroxypropyl Sulfo Betaine (HHSB), was screened to stabilize SC-CO2 foam. The properties of SC-CO2 foam were improved at elevated temperature and pressure. The effects of surfactant concentration, temperature, pressure and salinity on film drainage rate were measured to explore the stability of SC-CO2 foam. The results showed that an increase of surfactant concentration, pressure and salinity can decrease film drainage rate and enhance the foam stability, which was attributed to the increase of surfactant adsorption at the gas–liquid interface. The performance of SC-CO2 foam formed by HHSB was improved and the tolerant temperature was up to 100 °C. 1-D core flooding experiments indicated that compared with Coinjection of Surfactant and Gas (CSG) method the SC-CO2 foam generated through Surfactant-Alternative-Gas (SAG) method had lower foam strength but better in-depth migration capacity. The high temperature and pressure 3-D sand showed that in Water-Alternative-Gas (WAG) case CO2 broke early through the high permeability layers. In SAG case, SC-CO2 foam can improve the macroscopic sweep efficiency by reducing the CO2 mobility

On signed graphs whose spectral radius does not exceed 2+5\sqrt{2+\sqrt{5}}

The Hoffman program with respect to any real or complex square matrix $M$ associated to a graph $G$ stems from Hoffman's pioneering work on the limit points for the spectral radius of adjacency matrices of graphs does not exceed $\sqrt{2+\sqrt{5}}$. A signed graph $\dot{G}=(G,\sigma)$ is a pair $(G,\sigma),$ where $G=(V,E)$ is a simple graph and $\sigma: E(G)\rightarrow \{+1,-1\}$ is the sign function. In this paper, we study the Hoffman program of signed graphs. Here, all signed graphs whose spectral radius does not exceed $\sqrt{2+\sqrt{5}}$ will be identified.Comment: 29 pages, 18 figure

(E)-2-(Isonicotinoylhydrazonomethyl)benzoic acid methanol monosolvate

The title compound, C14H11N3O3·CH4O, was synthesized by the condensation reaction of isonicotinohydrazide with an equimolar quantity of 2-formylbenzoic acid in methanol. The hydrazone molecule displays an E configuration about the C=N bond. The dihedral angel between the pyridine and the benzene rings is 12.04 (5)°. In the crystal structure, molecules are linked by O—H...N, O—H...O and N—H...O hydrogen-bonding interactions