Multicomponent internal recalibration of an LC-FTICR-MS analysis employing a partially characterized complex peptide mixture: systematic and random errors

In high-throughput proteomics, a promising current approach is the use of liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS) of tryptic peptides from complex mixtures of proteins. To apply this method, it is necessary to account for any systematic measurement error, and it is useful to have an estimate of the random error expected in the measured masses. Here, we analyze by LC-FTICR-MS a complex mixture of peptides derived from a sample previously characterized by LC-QTOF-MS. Application of a Bayesian probability model of the data and partial knowledge of the composition of the sample suffice to estimate both the systematic and random errors in measured masses.     

Production of Well-Dispersed Aqueous Cross-Linked Chitosan-Based Nanomaterials as Alternative Antimicrobial Approach

In the current study, chitosan was extracted by deacetylation of chitin, which is extracted from shrimp shell. chitosan nanoparticles (CSNPs) were prepared by ionotropic gelation technique. chitosan/tripolyphosphate ratio (CS:TPP) was kept at 3:1 to prepare CSNPs. chitosan/silver nanocomposite (CS/AgNCs) were prepared by incorporating silver nanoparticles into CSNPs. The quality of the prepared nanocomposite was evaluated by infrared spectroscopy, UV–Vis spectroscopy, transmission electron microscopy, and antibacterial activity. Results showed that chitosan/silver nanocomposite in which, both chitosan and silver are in nanoscale was successfully prepared for the first time in a well-dispersed aqueous form. Whereas CSNPs act as a host material to form the nanocomposite unlike the previously prepared forms of chitosan–silver nanocomposites, that used chitosan bulk as host materials and the dispersion medium was slightly acidic. Moreover, results revealed that the antibacterial activity of CSNPs was significantly enhanced after incorporating trace amount of silver nanoparticles (0.535% w/w AgNPs/CSNPs).     

An Experimental and Numerical Study on the Effects of the Flat Heat Pipe Wick Structure on Its Thermal Performance

This paper presents an experimental and numerical work on the effect of flat heat pipe construction on the cooling of an electronic component. The flat heat pipe is heated via 1-cm-diameter circular electrical resistance (the evaporator side), and the other side (the condenser side) is cooled by convection through a heat sink. In the experimental work, three types of wick construction are used in the heat pipe: (A) mesh + powder, (B) mesh, and (C) powder. A comparison is performed of the electronic component cooling from the heat pipe, copper block, and open heat pipe constructions. The numerical work studies the effect of wick porosity on the heat pipe performance for different wicks that we could not study experimentally. For forced convection, heat pipe A is more efficient for the electronic component cooling than the copper block and other heat pipe construction. For free convection, the copper block is the most efficient. The maximum variation of the heat pipe temperature is about 19% due to change of the heat pipe construction. When the wick porosity increases, the temperature increases and the pressure decreases. The rectangular groove construction produces the minimum temperature compared to the wrapped screen and packed sphere constructions.     

Parallel matrix factorization-based collaborative sparsity and smooth prior for estimating missing values in multidimensional data

Pattern Analysis and Applications - Parallel matrix factorization has recently emerged as a powerful tool for low-rank tensor recovery problems. However, using only the low-rank property is often...     

MT1-MMP Cooperates with TGF-β Receptor-Mediated Signaling to Trigger SNAIL and Induce Epithelial-to-Mesenchymal-like Transition in U87 Glioblastoma Cells

Epithelial-to-mesenchymal transition (EMT) recapitulates metastasis and can be induced in vitro through transforming growth factor (TGF)-β signaling. A role for MMP activity in glioblastoma multiforme has been ascribed to EMT, but the molecular crosstalk between TGF-β signaling and membrane type 1 MMP (MT1-MMP) remains poorly understood. Here, the expression of common EMT biomarkers, induced through TGF-β and the MT1-MMP inducer concanavalin A (ConA), was explored using RNA-seq analysis and differential gene arrays in human U87 glioblastoma cells. TGF-β triggered SNAIL and fibronectin expressions in 2D-adherent and 3D-spheroid U87 glioblastoma cell models. Those inductions were antagonized by the TGF-β receptor kinase inhibitor galunisertib, the JAK/STAT inhibitors AG490 and tofacitinib, and by the diet-derived epigallocatechin gallate (EGCG). Transient gene silencing of MT1-MMP prevented the induction of SNAIL by ConA and abrogated TGF-β-induced cell chemotaxis. Moreover, ConA induced STAT3 and Src phosphorylation, suggesting these pathways to be involved in the MT1-MMP-mediated signaling axis that led to SNAIL induction. Our findings highlight a new signaling axis linking MT1-MMP to TGF-β-mediated EMT-like induction in glioblastoma cells, the process of which can be prevented by the diet-derived EGCG.     

Characterization of the absorption of theophylline from immediate- and controlled-release dosage forms with a numerical approach using the in vitro dissolution-permeation process using caco-2 cells

After oral administration, drug absorption rate is recognized to be dependent on two major factors: dissolution and intestinal cells permeability. Caco-2 monolayer cells have been largely used as a permeation study model. In this study, a numerical approach funded on an exponential first-order time relationship was tested to compare immediate- and controlled-release tablets of theophylline using a dissolution-permeation system. The dissolution performance using USP II paddle apparatus was coupled to the permeability studies investigated in Caco-2 cell monolayers. The dissolved samples were taken at different times; their pH and osmolarity were adjusted to render them suitable to Caco-2 permeability studies (osmolarity = 300 mosm, pH = 7.4). The experimental data show that the dissolution fits the exponential first-order relationship rate. The permeability values were in a range of 4.45 10(- 6)-5.28 10(- 6) cm/s, and percentages of absorbed drug dose were dependent on the fraction initially present in the donor compartment, indicating that absorption of theophylline was dissolution rate limited. Plotting experimental absorbed fractions (F(a)) against experimental dissolved fractions (F(d)) show that permeation is the rate-limiting step in drug absorption process in the extended release form of theophylline. Our results demonstrate a general agreement between observed F(a)/F(d) relationships and theoretical F(a)/F(d) relationships obtained with our approach funded on dissolution and permeation behavior. We concluded that the couple dissolution-caco-2 system could be a useful tool to characterize intestinal permeation for a new formulation of a drug compared with the conventional one.     

Preparation of nanocomposite materials from mercaptoacetate-modified platinum nanoparticles and a layered nickel hydroxyacetate salt

Nanocomposites were prepared by a very simple route from preformed platinum particles and a nickel layered hydroxide salt (LHS), these compounds being first synthesized separately by the polyol process. The nanoparticles were treated with mercaptoacetate before being brought into contact with the lamellar compound. XPS and IR spectroscopies give clear evidence for interactions between the platinum nanoparticles and the mercaptoacetate species. XRD, TEM and magnetic characterizations show that the structure of the nickel hydroxide layers is retained and that some of the LHS sheets contain incorporated nanoparticles.     

Heat transfer study in a rotor–stator system air-gap with an axial inflow

Discoidal rotor–stator systems are nowadays sometimes used in electrical wind generator. The cooling of such a system is a major problem due to the fact that high electrical losses are dissipated for relatively low rotational speed, responsible of the cooling. A new cooling solution is then investigated in this paper. So, this paper presents an experimental study of the local heat transfers on the rotor surface in the air-gap of a discoidal rotor–stator system, in which an air jet comes through the stator and impinges the rotor. To determine the surface temperatures, measurements were taken on the rotor, using an experimental technique based on infrared thermography. A thermal balance equation was used to identify the local convective heat transfer coefficient. The influence of the axial Reynolds number Re_j and the rotational Reynolds number Re was measured and compared with the data available in the literature. Local convective heat transfer coefficients were obtained for an inter-disk dimensionless spacing interval G ranging from 0.01 to 0.16 for Re_j between 0 and 41,666 and for Re between 20,000 and 516,000. The rotating disk can thus be divided into zones: one dominated by the air jet near the center of the rotor and one affected by both the air jet and rotation. Even though these two zones are not located in the same place on the disk, the heat transfers with non-zero impinging jets appear to be continuously improved compared to those with no jets. Critical radii over the rotor surface are identified and correlations are given.