Cross-correlation capillary electrophoresis in unmodified commercial equipment

The present contribution deals with the use of unmodified commercial equipment for cross-correlation capillary electrophoresis (CE). Complex injection sequences have been injected by switching sample and background electrolyte vials according to a preprogrammed order. Because of the nature of the auto-sampler used, no sequence could be injected in commercial instrument without high voltage (HV) interruptions. Apparently, this is the main reason why obtained signal-to-noise (S/N) ratios are lower than theoretical. Specific ways of programming the injection sequence and use of modified injection sequence in the correlation process have been used to overcome the deleterious effect caused by this sample injection. An electro-osmotic flow (EOF) marker was used as a sample to find optimal conditions for cross-correlation experiments. Best results demonstrate S/N ratio improvements around 2.8 compared to 4.0 theoretical maximu

Cleaning-up dirty isotachopherograms in time and frequency domain

In chromatography and electrophoresis S/N is increased by time or frequency domain filtering, multiple injections or sample stacking (in case of CZE). Bottom line is noise reduction without peak distortion. Isotachophoresis (ITP) using conductivity detection is also relevant because of its entirely different information content and the importance in CZE stacking. Several time- and frequency domain filters (Fourier & Walsh transform) were compared. Results were: • Time domain filters can be equally applied to either integral or differential signal; • Fourier and Walsh transforms are likewise suitable, whereas Walsh better preserves sharp boundaries; • Disturbance by detector transfer function can only be partly un-done with de-convolution; conditions are critical

Protein turnover forms one of the highest maintenance costs in Lactococcus lactis

Protein turnover plays an important role in cell metabolism by regulating metabolic fluxes. Furthermore, the energy costs for protein turnover have been estimated to account for up to a third of the total energy production during cell replication and hence may represent a major limiting factor in achieving either higher biomass or production yields. This work aimed to measure the specific growth rate (μ)-dependent abundance and turnover rate of individual proteins, estimate the ATP cost for protein production and turnover, and compare this with the total energy balance and other maintenance costs. The lactic acid bacteria model organism Lactococcus lactis was used to measure protein turnover rates at μ = 0.1 and 0.5 h-1 in chemostat experiments. Individual turnover rates were measured for ~75 % of the total proteome. On average, protein turnover increased by sevenfold with a fivefold increase in growth rate, whilst biomass yield increased by 35 %. The median turnover rates found were higher than the specific growth rate of the bacterium, which suggests relatively high energy consumption for protein turnover. We found that protein turnover costs alone account for 38 and 47 % of the total energy produced at μ = 0.1 and 0.5 h-1, respectively, and gene ontology groups Energy metabolism and Translation dominated synthesis costs at both growth rates studied. These results reflect the complexity of metabolic changes that occur in response to changes in environmental conditions, and signify the trade-off between biomass yield and the need to produce ATP for maintenance processes

Start-up of low-temperature anammox in UASB from mesophilic yeast factory anaerobic tank inoculum

201

Silver Nanoparticle Synthesis via Photochemical Reduction with Sodium Citrate

The aim of this paper is to provide a simple and efficient photoassisted approach to synthesize silver nanoparticles, and to elucidate the role of the key factors (synthesis parameters, such as the concentration of TSC, irradiation time, and UV intensity) that play a major role in the photochemical synthesis of silver nanoparticles using TSC, both as a reducing and stabilizing agent. Concomitantly, we aim to provide an easy way to evaluate the particle size based on Mie theory. One of the key advantages of this method is that the synthesis can be “activated” whenever or wherever silver nanoparticles are needed, by premixing the reactants and irradiating the final solution with UV radiation. UV irradiance was determined by using Keitz’s theory. This argument has been verified by premixing the reagents and deposited them in an enclosed space (away from sunlight) at 25 °C, then checking them for three days. Nothing happened, unless the sample was directly irradiated by UV light. Further, obtained materials were monitored for 390 days and characterized using scanning electron microscopy, UV-VIS, and transmission electron microscopy