Influence of die geometric parameters on plastic flow of layer composites during extrusion process

An analysis of the co-extrusion of layered composite (core–sleeve system) using various dies (mainly convex dies) is presented in this study. In order to determine the influence of the die geometry on the flow pattern of layered composite, experimental studies using metallic modelling material were carried out. The initial composite materials (billets) with different volume fraction of the components, their various arrangements in the billet, different yield stress ratios and extrusion ratios were applied. Based on the analysis of the grid distortion, the range of deformation zones and relative velocity distribution in the outlet region, the best convex die geometry in comparison with others has been proposed. Based on the experimental study, the dependence of maximum extrusion load on the angle of the die was determined. The results showed that using convex dies with a specific geometry selected for a layer composite cause, among other things, better equalisation of particle velocity in a die outlet.     

Influence of rolling direction on strength and ductility of aluminium and aluminium alloys produced by accumulative roll bonding

Sheets from commercial purity aluminium AA1050 and aluminium alloy AA6016 were processed by accumulative roll bonding to obtain an ultrafine-grained microstructure. The accumulative roll bonded samples showed a significant increase in specific strength paired with high ductility. Despite a strongly elongated grain structure, tensile testing of samples oriented 45° to the rolling direction revealed considerable improvement in elongation to failure compared to the samples oriented parallel to the rolling direction. From hydraulic bulge tests, it was observed that the accumulative roll bonded samples reached higher burst pressures and slightly lower equivalent strains in comparison to the as-received conventionally grain-sized samples. This behaviour reflects the extraordinary mechanical properties of the ultrafine-grained materials and indicates promising metal sheet formability.     

Struktur und Eigenschaften von Mischungen aus Polyamid 6 und isotaktischem Polypropylen,kompatibilisiert mit reaktiven Copolymeren auf der Basis von Polyethylen

Relations between the morphology and the properties of polyamide-6 (PA)/isotactic poly(propylene) (PP) blends were investigated. Poly(ethylene-co-vinyl acetate) and poly(ethylene-co-ethyl acrylate) functionalized with maleic anhydride were used as compatibilizers. The morphology of the blends and interaction between components were determined by simple thermodynamic analysis, differential scanning calorimetrie and electron microscopy. Fracture toughness and life-time measurements on model sandwich samples confirmed the good compatibilization effect of the used materials.     

Conductive blends of polyaniline with plasticized poly(methyl methacrylate)

Polyaniline (PANI) protonated with camphorsulfonic acid (CSA) and three different poly(alkylene phosphates) (PAPs) (where alkylene = pentylene, hexylene, or nonylene) was used in the fabrication of conductive polyaniline–poly(methyl methacrylate) (PMMA) blends. The lowest percolation threshold (f_p = 0.041 wt %) was obtained for the PANI(CSA)_0.5–PMMA blend plasticized with 35 wt % of dibutyl phtalate (DBPh). This blend is also very resistant against the deprotonation of its conductive phase in basic solutions of pH = 9. In the case of blends prepared with the use of PAPs as PANI dopants, the percolation threshold strongly depends on the length of the hydrophobic spacer (alkylene group) in the dopant. The percolation threshold decreases in the order PPP > PHP > PNP, whereas the resistance against deprotonation in basic solutions decreases in the following inverse order: PNP > PHP > PPP. This last observation can be rationalized by increasing contribution of hydrophobic segments in the polymeric dopant, when going from PPP to PNP, which renders polyaniline more resistance toward the penetration by aqueous basic solutions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 471–479, 1999     

Clinical Application Perspectives of Lung Cancers 3D Tumor Microenvironment Models for In Vitro Cultures

Despite the enormous progress and development of modern therapies, lung cancer remains one of the most common causes of death among men and women. The key element in the development of new anti-cancer drugs is proper planning of the preclinical research phase. The most adequate basic research exemplary for cancer study are 3D tumor microenvironment in vitro models, which allow us to avoid the use of animal models and ensure replicable culture condition. However, the question tormenting the scientist is how to choose the best tool for tumor microenvironment research, especially for extremely heterogenous lung cancer cases. In the presented review we are focused to explain the key factors of lung cancer biology, its microenvironment, and clinical gaps related to different therapies. The review summarized the most important strategies for in vitro culture models mimicking the tumor–tumor microenvironmental interaction, as well as all advantages and disadvantages were depicted. This knowledge could facilitate the right decision to designate proper pre-clinical in vitro study, based on available analytical tools and technical capabilities, to obtain more reliable and personalized results for faster introduction them into the future clinical trials.     

Alteration of Ethanol Reward by Prior Mephedrone Exposure: The Role of Age and Matrix Metalloproteinase-9 (MMP-9)

Mephedrone, a synthetic cathinone, is widely abused by adolescents and young adults. The aim of this study was to determine: (i) whether prior mephedrone exposure would alter ethanol reward and (ii) whether age and matrix metalloproteinase-9 (MMP-9) are important in this regard. In our research, male Wistar rats at postnatal day 30 (PND30) received mephedrone at the dose of 10 mg/kg, i.p., 3 times a day for 7 days. To clarify the role of MMP-9 in the mephedrone effects, one mephedrone-treated group received minocycline, as an MMP-9 antagonist. Animals were then assigned to conditioned place preference (CPP) procedure at PND38 (adolescent) or at PND69 (adult). After the CPP test (PND48/79), expression of dopamine D1 receptors (D1R), Cav1.2 (a subtype of L-type calcium channels), and MMP-9 was quantified in the rat ventral striatum (vSTR). The influence of mephedrone administration on the N-methyl-D-aspartate glutamate receptors (NMDAR) subunits (GluN1, GluN2A, and GluN2B) was then assessed in the vSTR of adult rats (only). These results indicate that, in contrast with adolescent rats, adult rats with prior mephedrone administration appear to be more sensitive to the ethanol effect in the CPP test under the drug-free state. The mephedrone effect in adult rats was associated with upregulation of D1R, NMDAR/GluN2B, MMP-9, and Cav1.2 signaling. MMP-9 appears to contribute to these changes in proteins expression because minocycline pretreatment blocked mephedrone-evoked sensitivity to ethanol reward. Thus, our results suggest that prior mephedrone exposure differentially alters ethanol reward in adolescent and adult rats.     

LC–ESI–MS/MS Identification of Polar Lipids of Two Thermophilic <Emphasis Type="Italic">Anoxybacillus</Emphasis> Bacteria Containing a Unique Lipid Pattern

Phospholipids and glycolipids from two recently described species belonging to the thermophilic genus Anoxybacillus were analyzed by liquid chromatography-electrospray tandem mass spectrometry (LC/ESI-MS/MS). Analysis of total lipids from the facultatively anaerobic A. bogrovensis on a HILIC (Hydrophilic Interaction LIquid Chromatography) column succeeded in separating diacyl- and plasmalogen phospholipids. The LC/ESI-MS/MS analysis of the strict aerobe A. rupiensis revealed the presence of different unique polar lipids, predominantly alanyl-, lysyl-, and glucosyl-phosphatidylglycerols and cardiolipins. Each of the classes of polar lipids was then analyzed by means of the ESI-MS/MS and more than 140 molecular species of six lipid classes from A. bogrovensis and nearly 200 molecular species of nine classes of polar lipids from A. rupiensis were identified. Five classes of unidentified polar lipids were detected in both strains. Plasmalogens were thus determined for the first time in a facultatively anaerobic bacterium, i.e. A. bogrovensis.     

Effect of frozen storage on the degree of vitamin B6degradation in different foods

Investigation of the effect of freezing and storage at-18° C for 5 months on the stability of total vitamin B₆ in foods of different origin leads to the conclusion that the decrease in vitamin B₆ content ranged from 18.92% to 60.26% and that the loss is significantly greater in food of animal origin (an average of 55.0%). Obviously, biostructure, that is chemical composition, is one of the basic factors affecting the degradation degree of vitamin B₆ in foods preserved by freezing. However, in relation of their biological value and with reference to the declaration allowing deep-frozen vegetables to be stored for 12–24 months, some foods of vegetable origin preserved by freezing exhibit a relatively high loss of biological value in terms of vitamin B₆ as early as after 5 months of storage.     

Internal locus of control and shiftwork effects

A range of situational, biological and psychological individual differences have been suggested to modify the impact of shift and night work. This paper discusses the development and application of a construct firmly based in the psychological/behavioural domain. The overall aim is to offer a theoretical standpoint with practical implications. Locus of Control theory has an extensive research history. In line with the evolution of thinking about this construct in terms of application in a context-specific sense, this paper describes the origins of internally-oriented Shiftwork Locus of Control (SHLOC) and presents its relationships with typically reported shiftwork-related outcomes. The SHLOC measure has been shown to be psychometrically robust and has demonstrated consistent patterns of relationships with shiftwork related variables that include sleep quality, fatigue, alertness, interference with family and social life, psychological well-being and perceived stress. In general, higher shiftwork-specific internality is associated with more positive outcomes (e.g. better sleep quality, lower fatigue, higher alertness) than lower shiftwork-specific internality. These findings hold true across a range of shiftwork situations and occupational groups. The construct has practical potential as an addition to shiftworker monitoring procedures that may be used to identify those individuals who may be more susceptible to the negative effects of shiftworking and, thereby, could benefit from targeted intervention.