Hydrophilic polycarbonate chips for generation of oil-in-water (O/W) and water-in-oil-in-water (W/O/W) emulsions

Modification of the surfaces of polycarbonate (PC) with the use of a solution of tin (II) chloride renders them hydrophilic. The surface draping is stable against exposure to water and to alcohols. Exposure to alkanes reduces but does not diminish the effect. The method is compatible—in using the same solvent and temperature—with the hydrophobic modification of PC (Jankowski et al. in Lab Chip 11:1151–1156, 2011). The combination of these methods makes it possible to generate single and multiple monodisperse emulsions with the use of flow-focusing junctions in systems made in PC—a material that is suitable for fabrication of multilayer, high-throughput microfluidic devices.     

Hydrophilic polycarbonate chips for generation of oil-in-water (O/W) and water-in-oil-in-water (W/O/W) emulsions

Modification of the surfaces of polycarbonate (PC) with the use of a solution of tin (II) chloride renders them hydrophilic. The surface draping is stable against exposure to water and to alcohols. Exposure to alkanes reduces but does not diminish the effect. The method is compatible—in using the same solvent and temperature—with the hydrophobic modification of PC Jankowski et al. ( Lab Chip 11:748–752, 2011). The combination of these methods makes it possible to generate single and multiple monodisperse emulsions with the use of flow-focusing junctions in systems made in PC—material that is suitable for fabrication of multilayer, high throughput microfluidic devices.     

Structure–Activity Relationships of JMV4463, a Vectorized Cathepsin D Inhibitor with Antiproliferative Properties: The Unique Role of the AMPA‐Based Vector

Cathepsin D (CathD) is overexpressed and secreted by several solid tumors and stimulates their growth, the mechanism of which is still not understood. In this context, the pepstatin bioconjugate JMV4463 [Ac‐arg‐O₂Oc‐(Val)₃‐Sta‐Ala‐Sta‐(AMPA)₄‐NH₂; O₂Oc=8‐amino‐3,6‐dioxaoctanoyl, Sta=statine, AMPA=ortho‐aminomethylphenylacetyl], containing a new kind of cell‐penetrating vector, was previously shown to exhibit potent antiproliferative effects in vitro and to delay the onset of tumors in vivo. In this study, we performed a structure–activity relationship analysis to evaluate the significance of the inhibitor and vector moieties of JMV4463. By modifying both statine residues of pepstatin we found that the antiproliferative activity is correlated with CathD inhibition, supporting a major role of the catalytic activity of intracellular CathD in cancer cell proliferation. Replacing the vector composed of four AMPA units with other vectors was found to abolish cytotoxicity, although all of the conjugates enabled pepstatin transport into cells. In addition, the AMPA₄ vector must be localized at the C terminus of the bioconjugate. The unexpected importance of the vector structure and position for cytotoxic action suggests that AMPA₄ enables pepstatin to inhibit the proteolysis of critical CathD substrates involved in cell proliferation via a unique mechanism of action.     

Prechamber NOx formation in low BMEP 2-stroke cycle natural gas engines

Precombustion chambers (PCCs) are an ignition technology for large bore, natural gas engines enabling increased combustion stability while extending the lean limit of operation. A PCC is a small chamber, typically 1–2% of the clearance volume, in which a near-stoichiometric mixture of fuel and air is ignited by a standard spark plug. After the mixture in the PCC is ignited, its pressure rises and expels a flame jet of hot gas mixture into the main chamber. The amount of energy a typical PCC produces is roughly one million times that of a conventional spark plug. In this work the role that the PCC plays in the formation of oxides of nitrogen (NO_x) is investigated. Previous research indicates that the PCC is responsible for a significant part of engine-out NO_x, especially near the lean limit of engine operation. Experimental results are presented from a large bore lean-burn 2-stroke cycle engine. The data shows that the PCC is responsible for a significant part of engine-out NO_x emissions. However, the PCC NO_x does not form in the PCC. Rather it forms within the gas jet after it penetrates into the main chamber combustion gases.     

Effective area of thin guarded electrode in determining of permittivity and volume resistivity

Effective area of guarded electrode is always larger than its geometrical area as a result of fringing effect. In most standards concerning permittivity and volume resistivity measurements, an increase in the effective fringing is assumed as a half of the width of the gap between the guarded electrode and the guard electrode (then the factor B = 1). In some standards, the increase calculated from Amey relation, is assumed to be smaller (B < 1). The Amey relation is exact only for sample permittivity ε→∞ . It is correct to apply the relation to calculate the volume resistivity, but it is incorrect to use it to calculate the permittivity of a sample. In this paper, a proper relation for the factor B has been derived analytically for thin electrodes made usually by thin film technology. The factor B can be used to calculate the permittivity of samples with arbitrary value of ε. Appropriate changes into the standard IEC 60250 and into other standards concerning permittivity measurements are proposed.     

Behavior of skew-bubbles in orthoferrites

Optical and magnetic properties of orthoferrite platelets with the optical axis normal to the surface have been investigated. A simple calculation has been performed indicating that a considerable increase of optical contrast between domains magnetized in opposite directions can be expected in such platelets when compared to the contrast obtainable in platelets with the crystalline "c" axis perpendicular to the surface. A numerical calculation has also beem performed for the stability range of a skew-bubble occuring in an orthoferrite platelet in which the magnetization is not perpendicular to the surface. It was found that this range is smaller and shifted to the lower bias fields than that for a normal bubble, amd that the ellipticity of a skew-bubble is larger. Experiments confirmed the theoretical prediction. On the basis of experimental results it was concluded that the shape of the skew-bubble wall is rather complex in thin platelet. This hypothesis has been confirmed to a certain degree by experiments performed on platelets with different thicknesses.