Factors Influencing the Reversion of Stress-induced Martensite to Austenite in a Fe-Mn-Si-Cr-Ni Shape Memory Alloy

It is well known that one way shape memory effect (SME) in Fe-Mn-Si-based shape memory alloys (SMAs) is related to the thermally induced reversion of ε (hexagonal close packed, hcp) stress-induced martensite (SIM) to γ (face centered cubic, fcc) austenite. In the case of a Fe-Mn-Si-Cr-Ni SMA, this reverse martensitic transformation was analyzed in regard to the critical temperature for the beginning of austenite formation (A _s) in different states characterized by quenching temperature and permanent tensile strain. For this purpose, dynamic mechanical analysis (DMA), dilatometry (DIL), differential thermal analysis (DSC), and optical microscopy (OM) were employed to determine the influence of quenching temperature and permanent tensile straining on SIM reversion to austenite during heating.     

Elasto-plastic localised responses in one-dimensional structural models

This work complements recent developments concerning the buckling of beams lying on a nonlinear (non-convex) elastic foundation, and also reports on some investigations on the role of material nonlinearity. Two structural models are studied using a simple elasto-plastic constitutive relationship, and buckling problems are formulated as reversible fourth-order differential equations. It is demonstrated that modulated responses are possible under certain circumstances. Some numerical simulations are presented supporting the analytical findings.     

Kinetic and Thermodynamic Studies of Emulsion Polymerization of a Sugar Monomer by Calorimetry with Compensation Heating and Differential Cooling

The kinetic and thermodynamic features of free‐radical batch emulsion polymerization of a sugar monomer (3‐MDG) and butyl acrylate (BA) were investigated in a power compensation calorimeter. The homopolymerizations as well as the copolymerization have been studied. The overall activation energy of 3‐MDG homopolymerization was 140 ± 3.8 kJ · mol^?1, the polymerization enthalpy was ΔH_MDG = ?51.6 ± 1.9 kJ · mol^?1 and the calculated adiabatic temperature rise was ΔT_ad = 78.5 K. The effects of the initiator and the emulsifier concentrations on the 3‐MDG/BA batch copolymerization kinetics and on the colloidal properties of the final sugar latexes were studied at 60 °C. At higher emulsifier and initiator concentration, respectively, the polymerization rate increases and the particle size decreases, but the trends do not conform to the Smith‐Ewart theory. Polydisperse sugar latex particles with a mean diameter in the range of 50–67 nm were obtained.

Relationship between the activation energy and the conversion for BA (open symbols) and 3‐MDG (solid symbols).     

Effect of Impurities on the Triple Point of Water: Experiments with Doped Cells at Different Liquid Fractions

Recent international comparisons showed that there is still room for improvement in triple point of water (TPW) realization uncertainty. Large groups of cells manufactured, maintained and measured in similar conditions still show a spread in the realized TPW temperature that is larger than the best measurement uncertainties (25 µK). One cause is the time-dependent concentration of dissolved impurities in water. The origin of such impurities is the glass/quartz envelope dissolution during a cell lifetime. The effect is a difference in the triple point temperature proportional to the impurities concentration. In order to measure this temperature difference and to investigate the effect of different types of impurities, we manufactured doped cells with different concentrations of silicon (Si), boron (B), sodium (Na) and potassium (K), the glass main chemical components. To identify any influence of the filling process, two completely independent manufacturing procedures were followed in two different laboratories, both national metrology institutes (VSL, Netherlands and UME, Turkey). Cells glass and filling water were also different while the doping materials were identical. Measuring the temperature difference as a function of the liquid fraction is a method to obtain information about impurities concentrations in TPW. Only cells doped with 1 µmol·mol^?1 B, Na and K proved to be suitable for measurements at different liquid fractions. We present here the results with related uncertainties and discuss the critical points in this experimental approach.     

Auswahl von Sorbenzien für die Gasphasenadsorption

Selection of Sorbents for Gas Phase Adsorption. For gas phase adsorption processes it is almost always necessary to select a suitable sorbent by experiment, i.e. a sorbent that is suitable for adsorption as well as for desorption. Therefore sorbents from the group of activated carbons, adsorbent resins and zeolites have been tested and compared with each other under adsorption and desorption conditions. The sorbents have also been checked for reliable function. Operational disturbances are often caused by components such as water vapor or (irreversibly adsorbing) high boiling components. In any case it is useful to select adsorbents which are not susceptible to interference by these components. The co-adsorption of water vapor, undesirable in practice, normally leads to a reduced adsorbent capacity. It is also shown that a single high boiling component, present in traces in the gas, loads the adsorbent to the same extent as the pure main component, so that there is hardly any capacity left for the main component. The range of investigation was insufficient to draw up general rules for the different groups of sorbents referring to the points considered.     

Context-adaptive forwarding in mobile opportunistic networks

When two opportunistic network peers encounter, utility functions are generally employed to select the messages that have to be exchanged, with the purpose of maximizing message delivery probability and reduce congestion. These functions compute weighted sums of various parameters, like centrality, similarity, and trust. Most of the existing solutions statically compute the weights based on offline observations and apply the same values regardless of a node’s context. However, mobile networks are not necessarily constant in terms of behavior and characteristics, so the classic approach might not be suitable. The network might be split into sub-networks, which behave differently from each other. Thus, in this paper, we show that, by dynamically adjusting the behavior of a node based on its context, through the adjustment of the utility function on the fly, the opportunistic forwarding process can be improved. We show that nodes behave differently from each other and have different views of the network. Through real-life trace-based simulations, we prove that our solution is feasible and is able to improve an opportunistic network’s performance from the standpoint of hit rate, latency, and delivery cost.     

Doping Experiments with Water Triple-Point Cells

Water triple-point cells were manufactured with the ad hoc addition of known amounts ((1 to 10) ??mol · mol^?1) of Si and Na impurities to cell high-purity water. The depressions of the triple-point temperatures realized by the doped cells with respect to 273.16 K were measured and found substantially different from what is expected by Raoult??s law for ideal diluted solutions.     

Current Trends in Neurodegeneration: Cross Talks between Oxidative Stress,Cell Death,and Inflammation

The human body is highly complex and comprises a variety of living cells and extracellular material, which forms tissues, organs, and organ systems. Human cells tend to turn over readily to maintain homeostasis in tissues. However, postmitotic nerve cells exceptionally have an ability to regenerate and be sustained for the entire life of an individual, to safeguard the physiological functioning of the central nervous system. For efficient functioning of the CNS, neuronal death is essential, but extreme loss of neurons diminishes the functioning of the nervous system and leads to the onset of neurodegenerative diseases. Neurodegenerative diseases range from acute to chronic severe life-altering conditions like Parkinson’s disease and Alzheimer’s disease. Millions of individuals worldwide are suffering from neurodegenerative disorders with little or negligible treatment available, thereby leading to a decline in their quality of life. Neuropathological studies have identified a series of factors that explain the etiology of neuronal degradation and its progression in neurodegenerative disease. The onset of neurological diseases depends on a combination of factors that causes a disruption of neurons, such as environmental, biological, physiological, and genetic factors. The current review highlights some of the major pathological factors responsible for neuronal degradation, such as oxidative stress, cell death, and neuroinflammation. All these factors have been described in detail to enhance the understanding of their mechanisms and target them for disease management.     

Preparation and characterization of bacterial cellulose-poly(vinyl alcohol) films with antimicrobial properties

Antimicrobial composites from poly(vinyl alcohol) and bacterial cellulose containing potassium sorbate as antimicrobial agent were obtained by film casting method. The obtained films were tested against Escherichia coli and showed a good antimicrobial activity.     

Effect of Impurities on Water Triple-Point Cells

Water triple-point cells are the basis for the definition of the kelvin and for the realization of the International Temperature Scale of 1990. The temperature differences between the cells are mainly caused by impurities arising in the cell water from the dissolution of the cell envelope (borosilicate glass or quartz). In order to investigate the effects of such impurities on the realized triple-point temperature, water triple-point cells doped with known amounts of Si and Na impurities ( \(0.1\,{\upmu }\hbox {mol}{\cdot }\hbox {mol}^{{-1}}\) to \(1\,{\upmu }\hbox {mol}{\cdot }\hbox {mol}^{{-1}}\) of Si and \(0.2\,{\upmu }\hbox {mol}{\cdot }\hbox {mol}^{{-1}}\) to \(2\,{\upmu }\hbox {mol}{\cdot }\hbox {mol}^{{-1}}\) of Na) were manufactured at VSL by adding gravimetric mixtures of a Si standard reference material and ultra high-purity water to the cell high-purity water. Water samples were taken from the manufactured cells, partitioned into three samples, and distributed to different laboratories for isotope and impurity analysis (inductively coupled plasma mass spectrometry, ICPMS). The results of two independent ICPMS analyses were compared with impurity calculations based on the gravimetric data of the prepared mixtures and manufactured cells. One undoped cell manufactured by UME and one undoped cell manufactured by VSL were intercompared at both VSL and SMD to demonstrate the equivalence of the manufacturing processes of UME and VSL. The triple-point temperatures realized by the doped cells and the undoped cell manufactured by VSL were measured at SMD. The results showed that, in doped cells, the equilibration time after the last freezing is directly dependent on the impurity concentration, and the temperature depression of doped triple-point-of-water cells is significantly greater than the values predicted by Raoult’s law for an ideal dilute solution.