SPR imaging biosensor for the 20S proteasome: sensor development and application to measurement of proteasomes in human blood plasma

The 20S proteasome is a multicatalytic enzyme complex responsible for intracellular protein degradation in mammalian cells. Its antigen level or enzymatic activity in blood plasma are potentially useful markers for various malignant and nonmalignant diseases. We have developed a method for highly selective determination of the 20S proteasome using a Surface Plasmon Resonance Imaging (SPRI) technique. It is based on the highly selective interaction between the proteasome’s catalytic β5 subunit and immobilized inhibitors (the synthetic peptide PSI and epoxomicin). Inhibitor concentration and pH were optimized. Analytical responses, linear ranges, accuracy, precision and interferences were investigated. Biosensors based on either PSI and epoxomicin were found to be suitable for quantitative determination of the proteasome, with a precision of ±10% for each, and recoveries of 102% and 113%, respectively, and with little interference by albumin, trypsin, chymotrypsin, cathepsin B and papain. The proteasome also was determined in plasma of healthy subjects and of patients suffering from acute leukemia. Both biosensors gave comparable results (2860 ng·mL-1 on average for control, and 42300 ng·mL-1 on average for leukemia patients)

Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank

9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved: the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and Conselleria de Pesca de la Xunta de GaliciaPeer reviewe

Local heat generation in a single stack lithium ion battery cell

The local heat generation in a single stack lithium ion battery cell was investigated as a function of the C-rate and state of charge (SoC). For that purpose, a custom build electrochemical cell design developed for local in-operando temperature measurements is used. The local temperature evolution in both electrodes and the separator is compared with local heat generation rates calculated from galvanostatic intermittent titration technique (GITT) measurements. The impact of reversible and irreversible heats is evaluated as a function of the C-rate and the SoC. The results reveal substantial differences in the local heat generation rates of the individual components of the battery cell related to their kinetic and thermodynamic properties. Significant SoC dependencies of the local reversible and irreversible heat generation are reflected by both the local temperature measurements and the heat generation rates calculated from GITT. A distinct asymmetry between charging and discharging is revealed which results from the intrinsic asymmetry of the reversible heat as well as differences in the kinetic limitations of the lithiation and delithiation of active materials. This study indicates, that the heat generation rates of the individual cell components should be considered accurately in order to build up basics for targeted material-, design- and thermal management optimization to handle thermal issues in large battery packs

Microscopic in-operando thermography at the cross section of a single lithium ion battery stack

A cell design to perform microscopic in-operando thermography across the interface anode — separator/electrolyte — cathode of a single lithium ion battery stack has been developed. A 3-electrode Swagelok® cell is adapted to enable the use of microscopic thermography during battery cycling. The developed measurement setup has been successfully tested using LiCoO2 as cathode, LiPF6 salt containing organic electrolyte and graphite as anode. The measurement results reveal differences in the heat generation of the individual components of the single battery stack. Furthermore, inhomogeneity in the electrodes can be detected and the heat transport on the micro scale can be observed. Keywords: Lithium batteries, Temperature measurement, Electrochemical cell desig

In situ temperature measurement on the metal/oxide/electrolyte interface during the anodizing of aluminum

The temperature development during anodizing processes plays a key role in the case of industrial hard anodizing processes. Commonly, only the bath temperature is controlled; although it is well known that the bath temperature can significantly deviate from the temperature across the interface metal/oxide/electrolyte no investigation is known which shows the temperature deviation in this area. The authors have built a special experimental setup which allows a local temperature measurement across the interface. The results show the possibility of local resolved temperature measurements and the calculation of the heat flow into the metal and the anodizing bath. Based on this knowledge a target control of the current-voltage-regime avoids the formation of thermally caused cracks in hard anodized layers