Relationships between biodiversity and multiple ecosystem functions (that is, ecosystem multifunctionality) are context-dependent. Both plant and soil microbial diversity have been reported to regulate ecosystem multifunctionality, but how their relative importance varies along environmental gradients remains poorly understood. Here, we relate plant and microbial diversity to soil multifunctionality across 130 dryland sites along a 4,000 km aridity gradient in northern China. Our results show a strong positive association between plant species richness and soil multifunctionality in less arid regions, whereas microbial diversity, in particular of fungi, is positively associated with multifunctionality in more arid regions. This shift in the relationships between plant or microbial diversity and soil multifunctionality occur at an aridity level of ∼0.8, the boundary between semiarid and arid climates, which is predicted to advance geographically ∼28% by the end of the current century. Our study highlights that biodiversity loss of plants and soil microorganisms may have especially strong consequences under low and high aridity conditions, respectively, which calls for climate-specific biodiversity conservation strategies to mitigate the effects of aridification.

A new method was developed to fabricate unique gold quasi-3D plasmonic nanostructures on poly(dimethylsiloxane) PDMS and 2D nanohole arrays on silicon as surface-enhanced Raman scattering (SERS) substrates using electron beam lithography (EBL) with negative tone resist Ma-N 2403 and soft lithography. The size and shape of nanopillars fabricated by EBL were well controlled via different beam conditions. An enhancement factor (EF) as high as 6.4 x 10(5) was obtained for 4-mercaptopyridine molecules adsorbed on the gold quasi-3D nanostructure array on PDMS with 400 nm diameter, 100 nm spacing and 300 nm depth, while no enhancement was observed for the gold 2D nanohole array on silicon with the same diameter and spacing. The experimental results were confirmed by finite-difference time-domain (FDTD) calculations. Furthermore, the calculated total electric fields showed that the strong SERS exhibited by the gold quasi-3D nanostructure arrays on PDMS is due to the strong localized electric fields at the gold-air interface of the bottom gold nanodisc. The strong and reproducible SERS spectroscopy for molecules adsorbed on precisely controlled gold quasi-3D nanostructure arrays on PDMS makes it possible for the integration of SERS-active nanopatterns into microfluidic devices as chemical and biological sensors with molecular specificity.

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Local electric fields can be tuned dramatically by varying the diameter of quasi-3D gold plasmonic nanostructure arrays, as indicated by 3D finite-difference time-domain calculations. Utilizing quasi-3D arrays that exhibit a maximum electric field intensity (i.e., a "hot" spot) either at the bottom (gold nanodisks) or on the top (gold film patterned with nanoholes), the optimal surface-enhanced Raman scattering (SERS) sensitivity for the detection of small molecules or large microorganisms can be achieved. The precisely fabricated and optimized SERS-active quasi-3D nanostructure arrays make it possible to quantitatively and reproducibly detect chemical and biological species using SERS, leading to a new sensing platform with molecular specificity based on SERS for many important applications.

Plantaricin MG is a 2,180-Da bacteriocin produced by Lactobacillus plantarum KLDS1.0391, which was isolated from Chinese traditional fermented cream. Plantaricin MG showed a broad inhibitory activity against not only Gram-positive bacteria but also Gram-negative bacteria including Listeria monocytogenes and Salmonella typhimurium. The mode of action of plantaricin MG on S. typhimurium was reported in this article. The addition of plantaricin MG to energized cells of S. typhimurium dissipated both, the transmembrane potential (Δψ) and the pH gradient (ΔpH). Energized membrane, obtained after the addition of glucose, was more susceptible to plantaricin MG action, leading to the release of intracellular K(+)ions, inorganic phosphate, ATP and UV-absorbing materials. These data suggest that the presence of a proton motive force promotes the interaction of plantaricin MG with the cytoplasmic membrane of energized cells, leading to pores formation which allows the efflux of ions, thereby ensuring efficient killing of target bacteria.

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The local electric field distribution and the effect of surface-enhanced Raman spectroscopy (SERS) were investigated on the quasi-3D (Q3D) plasmonic nanostructures formed by gold nanohole and nanodisc array layers physically separated by a dielectric medium. The local electric fields at the top gold nanoholes and bottom gold nanodiscs as a function of the dielectric medium, substrate, and depth of Q3D plasmonic nanostructures upon the irradiation of a 785 nm laser were calculated using the three-dimensional finite-difference time-domain (3D-FDTD) method. The intensity of the maximum local electric fields was shown to oscillate with the depth and the stronger local electric fields occurring at the top or bottom gold layer strongly depend on the dielectric medium, substrate, and depth of the nanostructure. This phenomenon was determined to be related to the Fabry-Pérot interference effect and the interaction of localized surface plasmons (LSPs). The enhancement factors (EFs) of SERS obtained from the 3D-FDTD simulations were compared to those calculated from the SERS experiments conducted on the Q3D plasmonic nanostructures fabricated on silicon and ITO coated glass substrates with different depths. The same trend was obtained from both methods. The capabilities of tuning not only the intensity but also the location of the maximum local electric fields by varying the depth, dielectric medium, and substrate make Q3D plasmonic nanostructures well suited for highly sensitive and reproducible SERS detection and analysis.