The influence of matrix chemical structure on the mode I and II interlaminar fracture toughness of glass‐fiber/epoxy composites

The present paper is concerned with Mode I and Mode II delamination tests performed on three different glass fiber reinforced epoxy composites, chosen to obtain different final structures. The effect of crosshead speed on the fracture resistance of the composites was also analyzed. It was found that Mode I propagation values (G_IC) increase as the crosshead speed decreases, probably because of the increase of brittleness in the studied range. An Arrhenius type relation between G_IC and the glass transition temperature of the epoxy resin/amine system (T_g) was found. Mode II initiation values (G_IIC^init) and apparent shear strength (S_H) were found to increase with the decrease of T_g. The relation between matrix toughness and composite interlaminar fracture toughness was also considered. Finally, the G_IC propagation values were compared to the data available in literature for similar materials.     

Exosomes and Brain Metastases: A Review on Their Role and Potential Applications

Brain metastases (BM) are a frequent complication in patients with advanced stages of cancer, associated with impairment of the neurological function, quality of life, prognosis, and survival. BM treatment consists of a combination of the available cancer therapies, such as surgery, radiotherapy, chemotherapy, immunotherapy and targeted therapies. Even so, cancer patients with BM are still linked to poor prognosis, with overall survival being reported as 12 months or less. Intercellular communication has a pivotal role in the development of metastases, therefore, it has been extensively studied not only to better understand the metastization process, but also to further develop new therapeutic strategies. Exosomes have emerged as key players in intercellular communication being potential therapeutic targets, drug delivery systems (DDS) or biomarkers. In this Review, we focus on the role of these extracellular vesicles (EVs) in BM formation and their promising application in the development of new BM therapeutic strategies.     

The importance of static friction characteristics of brake friction couple,and methods of testing

Detailed knowledge about static friction materials is required for the accurate calculation of the braking torque needed to hold a load at rest. This is particularly important for brakes in cranes, elevators, hoists and mining winding machines, which must meet specifications such as the definite value of the static safe braking factor. The study of static friction is also a useful supplement to the dynamic testing of brake friction materials. In such a study, precise control of the temperature on the surfaces is possible, as well as surface roughness, and existence of the third-body can be accurately identified. It is an important fact that the coefficient of static friction, μ_s, is not an invariant, and it cannot be adequately represented in many engineering applications as a single number. The study of static friction dependence upon factors such as stationary contact time, rate of tangential loading, and surface temperature, contributes to a better understanding of friction phenomena. In this paper, a test apparatus is presented, and a series of experiments is described. The experiments reveal the static friction characteristics of some brake friction materials.     

Effect of Low-Dose Ionizing Radiation on the Expression of Mitochondria-Related Genes in Human Mesenchymal Stem Cells

The concept of hormesis describes a phenomenon of adaptive response to low-dose ionizing radiation (LDIR). Similarly, the concept of mitohormesis states that the adaptive program in mitochondria is activated in response to minor stress effects. The mechanisms of hormesis effects are not clear, but it is assumed that they can be mediated by reactive oxygen species. Here, we studied effects of LDIR on mitochondria in mesenchymal stem cells. We have found that X-ray radiation at a dose of 10 cGy as well as oxidized fragments of cell-free DNA (cfDNA) at a concentration of 50 ng/mL resulted in an increased expression of a large number of genes regulating the function of the mitochondrial respiratory chain complexes in human mesenchymal stem cells (MSC). Several genes remained upregulated within hours after the exposure. Both X-ray radiation and oxidized cfDNA resulted in upregulation of FIS1 and MFN1 genes, which regulated fusion and fission of mitochondria, within 3–24 h after the exposure. Three hours after the exposure, the number of copies of mitochondrial DNA in cells had increased. These findings support the hypothesis that assumes oxidized cell-free DNA as a mediator of MSC response to low doses of radiation.     

Retrogradation of Starch in Cooked Wheat

Retrogradation phenomenon in cooked wheat grain was investigated by means of Differential Scanning Calorimetry (DSC) and mechanical compression tests. The extent of starch retrogradation as measured by endotherm increased with time. More importantly, the onset, peak and conclusion temperatures are dependent on the storage temperature and are significantly lower for grain stored at lower temperatures. The firmness of the grain due to starch crystallization as indicated by the elastic modulus also increased with time and was higher at lower storage temperatures. Lowered storage temperature not only accelerates starch recrystallization and thus firming process of the cooked grain, but also seems to generate a different organization in the ordering of the starch.     

Analytic–numerical approach in modeling electrodynamic phenomena of inductive dynamic drive

Inductive dynamic drives (IDD) are used in hybrid switching systems where a very quick contact separation as well as operation repeatability and long-term reliability are required. This paper presents more important existing examples of modeling the drive and their criticism. The author proposes a better model of electrodynamic inductive drive. Due to the cylindrical symmetry of the drives involved, a number of analytical dependencies were applied to develop the mathematical models. Additionally, the paper presents research results for a physical IDD model, those results determining the application range for the electrodynamic model assuming that the driven disc is perfectly stiff. Magnetic pressure acting on the disc obtained from the electrodynamic model can used as input in the mechanical model.     

Identification of Predictive Markers for Response to Neoadjuvant Chemoradiation in Rectal Carcinomas by Proteomic Isotope Coded Protein Label (ICPL) Analysis

Neoadjuvant chemoradiation (nCRT) is an established procedure in stage union internationale contre le cancer (UICC) II/III rectal carcinomas. Around 53% of the tumours present with good tumor regression after nCRT, and 8%–15% are complete responders. Reliable selection markers would allow the identification of poor or non-responders prior to therapy. Tumor biopsies were harvested from 20 patients with rectal carcinomas, and stored in liquid nitrogen prior to therapy after obtaining patients’ informed consent (Erlangen-No.3784). Patients received standardized nCRT with 5-Fluoruracil (nCRT I) or 5-Fluoruracil ± Oxaliplatin (nCRT II) according to the CAO/ARO/AIO-04 protocol. After surgery, regression grading (Dworak) of the tumors was performed during histopathological examination of the specimens. Tumors were classified as poor (Dworak 1 + 2) or good (Dworak 3 + 4) responders. Laser capture microdissection (LCM) for tumor enrichment was performed on preoperative biopsies. Differences in expressed proteins between poor and good responders to nCRT I and II were identified by proteomic analysis (Isotope Coded Protein Label, ICPL™) and selected markers were validated by immunohistochemistry. Tumors of 10 patients were classified as histopathologically poor (Dworak 1 or 2) and the other 10 tumor samples as histopathologically good (Dworak 3 or 4) responders to nCRT after surgery. Sufficient material in good quality was harvested for ICPL analysis by LCM from all biopsies. We identified 140 differentially regulated proteins regarding the selection criteria and the response to nCRT. Fourteen of these proteins were synchronously up-regulated at least 1.5-fold after nCRT I or nCRT II (e.g., FLNB, TKT, PKM2, SERINB1, IGHG2). Thirty-five proteins showed a complete reciprocal regulation (up or down) after nCRT I or nCRT II and the rest was regulated either according to nCRT I or II. The protein expression of regulated proteins such as PLEC1, TKT, HADHA and TAGLN was validated successfully by immunohistochemistry. ICPL is a valid method to identify differentially expressed proteins in rectal carcinoma tissue between poor vs. good responders to nCRT. The identified protein markers may act as selection criteria for nCRT in the future, but our preliminary findings must be reproduced and validated in a prospective cohort.