Oriented 2D covalent organic framework thin films on single-layer graphene

Covalent organic frameworks (COFs), in which molecular building blocks form robust microporous networks, are usually synthesized as insoluble and unprocessable powders. We have grown two-dimensional (2D) COF films on single-layer graphene (SLG) under operationally simple solvothermal conditions. The layered films stack normal to the SLG surface and show improved crystallinity compared with COF powders. We used SLG surfaces supported on copper, silicon carbide, and transparent fused silica (SiO(2)) substrates, enabling optical spectroscopy of COFs in transmission mode. Three chemically distinct COF films grown on SLG exhibit similar vertical alignment and long-range order, and two of these are of interest for organic electronic devices for which thin-film formation is a prerequisite for characterizing their optoelectronic properties.     

Antigen delivery systems and immunostimulation

The immune system evolved to free the host from invading noxious pathogens. Vaccines are inoculated as a prophylactic measure in order to program the immune system for accelerated recognition and elimination of specific pathogens. During vaccination the immune system is exposed to attenuated or inactivated microorganisms, or their fragments. The immune response to these structures, in contrast to virulent pathogens, is often inadequate for the generation of memory cells or immune effector elements such as antibodies, perforines, granzymes or cytokines. Vaccine adjuvants help to overcome these limited responses. They provide instructive signals for the host immune system by mimicking the conditions associated with virulent infection. Hence, they either enhance and prolong expression of antigen components to reactive T cells in lymph nodes (signal 1) or they increase expression of membrane-bound or soluble costimulatory molecules (signal 2). The enhancement of both signals by vaccine adjuvants is not mutually exclusive. Moreover, adjuvants may encode a third signal instructing the type of immune reaction to be generated. Supported by animations this presentation addresses putative immunological concepts of vaccine adjuvant activity, a phenomenon long been known as "the immunologist's dirty little secret". Insight in the mechanisms that underlie adjuvant-induced immunostimulation and generation of memory cells will facilitate rational vaccine design.     

Patterns of effects of arbuscular mycorrhizal fungi on plants grown in contaminated soil

Arbuscular mycorrhizal fungi (AMF) are integral functioning parts of plant root systems and are widely recognized for enhancing plant growth on severely disturbed sites, including those contaminated with heavy metals. However, the generality of detailed patterns observed for their influence on various metals and oxidative‐stress parameters in multiple plant species is not clarified. The goal of this study was to investigate the patterns of metal‐stress alleviation by AMF in four plant species. For this purpose, clover, sunflower, mustard, and phacelia were inoculated with Glomus intraradices and compared to noninoculated plants grown under heavy metal–stressed conditions. The study focused on the effect of AMF inoculation on plant biomass, assimilating pigments, total protein, superoxide dismutase and peroxidase activity, lipid peroxidation and As, Cd, Co, Cu, Fe, Mn, P, Pb, U, and Zn contents. As a result of inoculation very different patterns of variation were obtained for concentrations of elements and for biochemical parameters in plants. The particular effect of AMF inoculation on plants was species‐ and metal‐specific, although there was a general enhancement of plant growth.     

Bragg soybeans grown on a southern coastal plains soil i. dry matter distribution,nodal growth analysis,and sample variability

Yields of soybean [Glycine max (L.) Merr.] are affected by the manner in which available resources are partitioned into component plant parts. Little is known about these partitioning processes and much of what has been reported describes indeterminate cultivars or comes from other than field studies. A field investigation was conducted, therefore, on a Goldsboro loamy sand (Aquic Paleudult) to characterize in detail the growth and development of a determinate soybean cultivar ‘Bragg’. Soybean were grown in well watered field plots in four replications from each of which 4 nested samples of 0.3 m² each were combined at each sampling. Leaf area, dry matter production, internode length, and sample variability were determined nodally at 10‐ to 14‐day intervals from 7 July to 17 October. Plant components at each node were separated into stems, leaf blades, pods, and petioles. Primary and secondary branches were combined in the petiole fraction.

Maximum above ground plant dry weight achieved was 1027 g/m² and maximum combined nodal dry weight was 92 g/m² (at node 8), both occurring at the R7 growth stage. Canopy dry weight distribution over time was unique for each plant part. Growth analyses showed that RGR, NAR, LAR, and LWR declined with plant age at a rate that could be described with either linear or exponential models. A maximum CGR of 16.24 g/m²/day occurred at mid‐podfill and declined thereafter due to maturity. Leaf area per node peaked between nodes 7 and 12, decreasing uniformly toward the top of the canopy. Maximum nodal LAI was 0.79 at node 7 on 31 August.

Distribution of dry weight among parts varied with plant age and node position. Maximum dry weights of stems (276 g/m²), petioles (253 g/m²), and leaves (263 g/m²) were found during mid‐podfill. During mid‐August, the dry weights of the stems, petioles, and leaves were similar and approximately 250 g/m². Stem dry weights had the lowest coefficients of variation of all plant fractions once maximum dry weight was achieved. Internode length varied along the stem with the maximum at node 12. By bloom, expansion of the internodes lower than 12 had ceased; expansion of the eight higher internodes ceased three weeks later. During vegetative growth, the ratio of stem internodal dry weight to internodal length had peak values at the lowest and highest internodes. During reproductive growth, the ratio decreased linearly with internode number. Coefficients of variation (CV) for the combined weight of plant parts, and for stems, petioles, leaves, and pods were relatively constant during the season and were 24.8, 23.4, 38.2, 25.5, and 26.8%, respectively. The CV's for the combined weight of plant parts were somewhat higher at the lowest and uppermost nodes. This variability resulted from the abscission of petioles and leaves in the lower nodes and the initiation of leaves, petioles, and pods in the upper nodes where rapid growth and development was occurring. Time from node initiation to achievement of lowest stable CV was determined for each node and plant part. Plant node position and morphological part with the lowest CV was identified for each sampling date (and growth stage).     

Giant supramolecular liquid crystal lattice

Self-organized supramolecular organic nanostructures have potential applications that include molecular electronics, photonics, and precursors for nanoporous catalysts. Accordingly, understanding how self-assembly is controlled by molecular architecture will enable the design of increasingly complex structures. We report a liquid crystal (LC) phase with a tetragonal three-dimensional unit cell containing 30 globular supramolecular dendrimers, each of which is self-assembled from 12 dendron (tree-like) molecules, for the compounds described here. The present structure is one of the most complex LC phases yet discovered. A model explaining how spatial arrangement of self-assembled dendritic aggregates depends on molecular architecture and temperature is proposed.     

Simazine dealkylation in conjunction with citrus roots

Simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) was metabolised by dealkylation in the presence of citrus tree roots growing in nutrient solution. Dehalogenation to hydroxysimazine was not observed. Removal of citrus roots from the solution caused dealkylation to cease. Dealkylation did not occur in the nutrient solution in the absence of roots.