Several chemical changes in soil are associated with plant growth-promoting rhizobacteria (PGPR). Some bacterial strains directly regulate plant physiology by mimicking synthesis of plant hormones, whereas others increase mineral and nitrogen availability in the soil as a way to augment growth. Identification of bacterial chemical messengers that trigger growth promotion has been limited in part by the understanding of how plants respond to external stimuli. With an increasing appreciation of how volatile organic compounds signal plants and serve in plant defense, investigations into the role of volatile components in plant–bacterial systems now can follow. Here, we present chemical and plant-growth data showing that some PGPR release a blend of volatile components that promote growth of Arabidopsis thaliana. In particular, the volatile components 2,3-butanediol and acetoin were released exclusively from two bacterial strains that trigger the greatest level of growth promotion. Furthermore, pharmacological applications of 2,3-butanediol enhanced plant growth whereas bacterial mutants blocked in 2,3-butanediol and acetoin synthesis were devoid in this growth-promotion capacity. The demonstration that PGPR strains release different volatile blends and that plant growth is stimulated by differences in these volatile blends establishes an additional function for volatile organic compounds as signaling molecules mediating plant–microbe interactions

A large and high-quality single crystal (Li 0.84 Fe 0.16 )OHFe 0.98 Se, the optimal superconductor of newly reported (Li 1-x Fe x )OHFe 1-y Se system, has been successfully synthesized via a hydrothermal ion-exchange technique. The superconducting transition temperature (T c ) of 42 K is determined by magnetic susceptibility and electric resistivity measurements, and the zero-temperature upper critical magnetic fields are evaluated as 79 and 313 Tesla for the field along the c-axis and the ab-plane, respectively. The ratio of out-of-plane to in-plane electric resistivity,ρ c /ρ ab , is found to increases with decreasing temperature and to reach a high value of 2500 at 50 K, with an evident kink occurring at a characteristic temperature T*=120 K. The negative in-plane Hall coefficient indicates that electron carriers dominate in the charge transport, and the hole contribution is significantly reduced as the temperature is lowered to approach T*. From T* down to T c , we observe the linear temperature dependences of the in-plane electric resistivity and the magnetic susceptibility for the FeSe layers. Our findings thus reveal that the normal state of (Li 0.84 Fe 0.16 )OHFe 0.98 Se becomes highly two-dimensional and anomalous prior to the superconducting transition, providing a new insight into the mechanism of high-T c superconductivity.

Zeolites have been widely used in industry owing to their ordered micropores and stable frameworks. The pore sizes and shapes are the key parameters that affect the selectivity and efficiency in their applications in catalysis, sorption, and separation. Zeolites with pores defined by 10 and 12 TO4 tetrahedra are often used for various catalytic processes. To optimize the performance of zeolites, it is extremely desirable to fine-tune the pore sizes/shapes. The first germanosilicate zeolite with a three-dimensional 11×11×12-ring channel system, PKU-16 (PKU, Peking University) is presented. Nanosized PKU-16 was structurally characterized by the new three-dimensional rotation electron diffraction (RED) technique. PKU-16 is structurally related to the zeolite β polymorph C (BEC, 12×12×12-ring channels) by rotating half of the four-rings in double mtw units.