Enhancement of cellulose degradation in freshwater sediments by a sediment microbial fuel cell.

OBJECTIVE: To demonstrate that an enhanced sediment microbial fuel cell (SMFC) system can accelerate the degradation of cellulose in fresh water sediments as the accumulation of cellulose in lake sediments may aggravate the lake marsh, increase organic matter content and result in rapid deterioration of water quality and damage the ecosystem. RESULTS: After 330 days the highest cellulose removal efficiency (72.7 ± 2.1 %) was achieved in the presence of a SMFC with a carbon nanotube decorated cathode, followed by a SMFC without the cathode decoration (64.4 ± 2.8 %). The lowest cellulose removal efficiency (47.9 ± 2.1 %) was in the absence of SMFC. The sediment characterization analysis confirmed that the carbon nanotube decorated cathode enhances the electron transfer rate in the SMFC and improves the dissolved organic matter oxidation rate. CONCLUSION: This study offers a relatively simple and promising new method for cellulose degradation in sediment.

Fabricating nanoscale chemical gradients with ThermoChemical NanoLithography.

Production of chemical concentration gradients on the submicrometer scale remains a formidable challenge, despite the broad range of potential applications and their ubiquity throughout nature. We present a strategy to quantitatively prescribe spatial variations in functional group concentration using ThermoChemical NanoLithography (TCNL). The approach uses a heated cantilever to drive a localized nanoscale chemical reaction at an interface, where a reactant is transformed into a product. We show using friction force microscopy that localized gradients in the product concentration have a spatial resolution of ~20 nm where the entire concentration profile is confined to sub-180 nm. To gain quantitative control over the concentration, we introduce a chemical kinetics model of the thermally driven nanoreaction that shows excellent agreement with experiments. The comparison provides a calibration of the nonlinear dependence of product concentration versus temperature, which we use to design two-dimensional temperature maps encoding the prescription for linear and nonlinear gradients. The resultant chemical nanopatterns show high fidelity to the user-defined patterns, including the ability to realize complex chemical patterns with arbitrary variations in peak concentration with a spatial resolution of 180 nm or better. While this work focuses on producing chemical gradients of amine groups, other functionalities are a straightforward modification. We envision that using the basic scheme introduced here, quantitative TCNL will be capable of patterning gradients of other exploitable physical or chemical properties such as fluorescence in conjugated polymers and conductivity in graphene. The access to submicrometer chemical concentration and gradient patterning provides a new dimension of control for nanolithography.

In-depth profiles of bioactive large molecules in saliva secretions of leeches determined by combining salivary gland proteome and transcriptome data.

Medicinal leeches have been widely utilized in medical procedures for thousands of years. The application of leeches depends on the components of leech saliva secretions and active molecules, but many components of the secretions are not well characterized due to their low concentration and abundance. Determination of the profiles of leech salivary secretions is important to its medicinal application. In this study, we performed an in-depth proteomic analysis of leech salivary glands and deduced 434 full-length protein sequences from combined leech proteome and transcriptome databases. After integrating data from both datasets, forty-four proteins and two hundred twenty-one transcripts of bioactive molecules were involved in leech sucking pathways. Using gene expression analysis, we found that two-thirds of bioactive genes played key roles in leech bite processes and were associated cave-dwelling habitats. Our results indicate that the treatment efficiency can differ depending on the sucking leech species. Moreover, combining high-throughput proteomic and transcriptomic analyses is effective for the determination of wide profiles of proteins that are present at low concentrations in secretions. These findings highlight the extensive diversity of bioactive molecules and provide a new foundation for performing novel investigations and discovering future pharmacological agents or targets in leech medicinal therapy. SIGNIFICANCE: Medicinal leech therapy has been used for many centuries depending on the components of leech saliva secretions and active actions, but many components of the secretions were less known due to its low concentration and abundance. Determination of the profiles of leech salivary secretions is important to its medicinal application. Hereby, the molecular information provided by proteomic and transcriptomic analysis can be used to develop a more thorough understanding of leech sucking pathway and medicinal application. It provided a new foundation for performing novel investigations and discovering future pharmacological agents or targets in leech medicinal therapy.