Flash pyrolysis of biomass: a review of recent advances

Clean Technologies and Environmental Policy - To assuage global consumer demand for energy, there is a need for increased biofuel production. Flash pyrolysis is an important technique for biomass...     

Optimization of photosynthetic hydrogen yield from platinized photosystem I complexes using response surface methodology

Light-dependent hydrogen production by platinized Photosystem I isolated from the cyanobacterium Thermosynechococcus elongatus BP-1 was optimized using response surface methodology (RSM). The process parameters studied included temperature, light intensity and wavelength, and platinum salt concentration. Application of RSM generated a model that agrees well with the data for H₂ yield (R² = 0.99 and p < 0.001). Significant effects on the total H₂ yield were seen when the platinum salt concentration and temperature were varied during platinization. However, light intensity during platinization had a minimal effect on the total H₂ yield within the region studied. The values of the parameters used during the platinization that optimized the production of H₂ were light intensity of 240 μE m⁻² s⁻¹, platinum salt concentration of 636 μM and temperature of 31 °C. A subsequent validation experiment at the predicted conditions for optimal process yield gave the maximum H₂ yield measured in the study, which was 8.02 μmol H₂ per mg chlorophyll.     

Effect of Divalent Metal Ion on the Structure,Stability and Function of Klebsiella pneumoniae Nicotinate-Nucleotide Adenylyltransferase: Empirical and Computational Studies

The continuous threat of drug-resistant Klebsiella pneumoniae justifies identifying novel targets and developing effective antibacterial agents. A potential target is nicotinate nucleotide adenylyltransferase (NNAT), an indispensable enzyme in the biosynthesis of the cell-dependent metabolite, NAD⁺. NNAT catalyses the adenylation of nicotinamide/nicotinate mononucleotide (NMN/NaMN), using ATP to form nicotinamide/nicotinate adenine dinucleotide (NAD⁺/NaAD). In addition, it employs divalent cations for co-substrate binding and catalysis and has a preference for different divalent cations. Here, the biophysical structure of NNAT from K. pneumoniae (KpNNAT) and the impact of divalent cations on its activity, conformational stability and substrate-binding are described using experimental and computational approaches. The experimental study was executed using an enzyme-coupled assay, far-UV circular dichroism, extrinsic fluorescence spectroscopy, and thermal shift assays, alongside homology modelling, molecular docking, and molecular dynamic simulation. The structure of KpNNAT revealed a predominately α-helical secondary structure content and a binding site that is partially hydrophobic. Its substrates ATP and NMN share the same binding pocket with similar affinity and exhibit an energetically favourable binding. KpNNAT showed maximum activity and minimal conformational changes with Mg²⁺ as a cofactor compared to Zn²⁺, Cu²⁺ and Ni²⁺. Overall, ATP binding affects KpNNAT dynamics, and the dynamics of ATP binding depend on the presence and type of divalent cation. The data obtained from this study would serve as a basis for further evaluation towards designing structure-based inhibitors with therapeutic potential.     

An analysis of the performance of an anaerobic dual anode-chambered microbial fuel cell

The performance of a dual anode-chambered microbial fuel cell (MFC) inoculated with Shewanella oneidesis MR-1 was evaluated. This reactor was constructed by incorporating two anode chambers flanking a shared air cathode chamber in an electrically parallel, geometrically stacked arrangement. The device was shown to have the same maximum power density (approximately 24 W m⁻³, normalized by the anode volume) as a single anode-, single cathode-chambered MFC. The dual anode-chambered unit generated a maximum current of 3.66 mA (at 50 Ω), twice the value of 1.69 mA (at 100 Ω) for the single anode-chambered device at approximately the same volumetric current density. Increasing the Pt-coated cathode surface area by 100% (12 to 24 cm²) had no significant effect on the power generation of the dual anode-chambered MFC, indicating that the performance of the device was limited by the anode. The medium recirculation rate and substrate concentration in the anode were varied to determine their effect on the anode-limited power density. At the highest recirculation rate, 5 ml min⁻¹, the power density was about 25% higher than at the lowest recirculation rate, 1 ml min⁻¹. The dependence of the power density on the lactate concentration showed saturation kinetics with a half-saturation constant K_s on the order of 4.4 mM.