Desorption Kinetics of Volatile in Condensed Mode Polyethylene Process

In this paper the desorption kinetics of volatile in condensed mode polyethylene process is studied through experiments. It is found that though the residual volatile in particles at the later stage of desorption accounts for a relatively small portion of the total quantity, the desorption of this part of volatile requires much longer time than at the earlier stage. For high requirement of devolatilization, the total time needed will be predominately determined by the residual amount of volatile in particles. Temperature has greater effect on the desorption rate than other influence factors, especially in the later period of desorption. A model is proposed to calculate the volatile desorption rate for condensed mode polyethylene process.

Hydrogen transport in metals: Integration of permeation, thermal desorption and degassing

A modelling suite for hydrogen transport during electrochemical permeation, degassing and thermal desorption spectroscopy is presented. The approach is based on Fick＇s diffusion laws, where the initial concentration and diffusion coefficients depend on microstructure and charging conditions. The evolution equations are shown to reduce to classical models for hydrogen diffusion and thermal desorption spectroscopy. The number density of trapping sites is found to be proportional to the mean spacing of each microstructural feature, including dislocations, grain boundaries and various precipitates. The model is validated with several steel grades and polycrystalline nickel for a wide range of processing conditions and microstructures. A systematic study of the factors affecting hydrogen mobility in martensitic steels showed that dislocations control the effective diffusion coefficient of hydrogen. However,they also release hydrogen into the lattice more rapidly than other kind of traps. It is suggested that these effects contribute to the increased susceptibility to hydrogen embrittlement in martensitic and other high-strength steels. These results show that the methodology can be employed as a tool for alloy and process design, and that dislocation kinematics play a crucial role in such design.

Serum peptidome profiling for identifying pathological patterns in patients with primary nephrotic syndrome

Background Renal biopsy is necessary for diagnosing the pathological changes of primary nephrotic syndrome （NS）. However, it is invasive, time-consuming and can not be performed frequent on the same patient. Thus, development of a non-invasive and rapid diagnostic method may improve clinical patient management. Methods Proteomic tool magnetic bead-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MB-based MALDI TOF MS） was applied to serum to determine peptidome patterns that are characteristic of different pathological changes. Results Serum specimen from 114 patients with NS （62 were minimal change disease （MCD）, 30 were membranous nephropathy （MN）, and 22 were focal segmental glomerulosclerosis （FSGS）） and 60 normal individuals were analyzed using MB-based MALDI TOF MS. The peptidome pattern was generated by genetic algorithms using a training set of 31 MCD, 15 MN, 11 FSGS and 30 normal individuals and was validated by an independent testing set of the remaining samples. The serum peptidome pattern, based on a panel of 14 peaks, accurately recognized samples from MCD, MN, FSGS and healthy control with sensitivities of 93.5%, 86.7%, 63.6% and 90.0%, and specificities of 98.2%, 94.4%, 100% and 89.5%, respectively. Moreover, one peptide from peptidome pattern was identified by liquid chromatography tandem mass spectrometry （LC MS/MS） as fibrinogen A. Conclusion Detection of the serum peptidome pattern is a rapid, non-invasive, high-throughout, and reproducible method for identifying the pathological patterns of patients with nephrotic syndrome.