Experimental Modelling of the Impact of a DC Magnetic Field on the Melt Flow in a Continuous Casting Mould

This paper describes experimental investigations of flow structures and related transport processes in the continuous casting mould under the influence of an external DC magnetic field at laboratory scale.Experimental results will be presented here which have been obtained using a physical model(mini-LIMMCAST)operating with the low melting point alloy GaInSn.According to the concept of the electromagnetic brake the impact of a DC magnetic field on the outlet flow from the Submerged Entry Nozzle(SEN)has been studied up to Hartmann numbers of about 400.The Ultrasound-Doppler-Velocimetry(UDV)was applied for measurements of the flow pattern in the mould.Local conductivity anemometers were used to measure the turbulent quantities of the flow.The effect of the magnetic field on the flow structure turned out to be manifold and rather complex.The magnetic field causes a deflection of the jet,at which the respective exit angle from the nozzle ports becomes more flat.Thus,both the penetration depth of the discharging flow into the lower part of the mould and the impinging velocity of the jet onto the side wall are reduced.A significant return flow occurs in the adjacent regions of the jet.Specific vortices are formed with axes being aligned with the magnetic field direction.Such vortical structures are typical for quasi-two-dimensional magneto-hydrodynamic(MHD)flows.The flow measurements do not manifest a general braking effect which would be expected as an overall damping of the flow velocity and the related fluctuations all-over the mould volume.Variations of the wall conductivity showed a striking impact on the resulting flow structures.     

An Unexpected Mixture of Substances in the Defensive Secretions of the Tubuliferan Thrips, Callococcithrips fuscipennis (Moulton)

Adults and larvae of the thrips Callococcithrips fuscipennis (Moulton) (Thysanoptera: Tubulifera: Phlaeothripidae) live in the sticky wax masses of adult females of the felt scale insect Callococcus acaciae (Maskell) (Sternorrhyncha: Coccoidea: Eriococcidae). The scale is sessile and feeds on Kunzea shrubs (Myrtales: Myrtaceae). If stressed, the thrips produce droplets of secretions. The mixture contains pentadecane, tridecane, two monoterpenoids, hexadecyl butanoate, and smaller amounts of 15 other esters of long-chain unbranched alcohols identified as acetates, butanoates, hexanoates, and octanoates. The monoterpenoids are dolichodial, an iridoid, and an unknown substance with a mass spectrum very similar to that of anisomorphal and peruphasmal, diastereomers of dolichodial, but with a different retention time. Iridoids, butanoates, hexanoates, and octanoates have not been previously identified in Thysanoptera.     

Analysis of OPLA scaffolds for bone engineering constructs using human jaw periosteal cells

For bone regeneration constructs using human jaw periosteal cells (JPC) the extent of osteoinductive ability of different three-dimensional scaffolds is not yet established. We analyzed open-cell polylactic acid (OPLA) scaffolds for their suitability as bone engineering constructs using human JPC. Cell adhesion and spreading was visualized on the surface of scaffolds by scanning electron microscopy. JPC proliferation within OPLA scaffolds was compared with proliferation within collagen and calcium phosphate scaffolds. We found a significant increase of proliferation rates in OPLA scaffolds versus Coll/CaP scaffolds at three time points. Live-measurements of oxygen consumption within the cell-seeded scaffolds indicate that the in vitro culturing time should not exceed 12–15 days. OPLA scaffolds, which were turned out to be the most beneficial for JPC growth, were chosen for osteogenic differentiation experiments with or without BMP-2. Gene expression analyses demonstrated induction of several osteogenic genes (alkaline phosphatase, osterix, Runx-2 and insulin-like growth factor) within the 3D-scaffolds after 12 days of in vitro culturing. Element analysis by EDX spectrometry of arising nodules during osteogenesis demonstrated that JPC growing within OPLA scaffolds are able to form CaP particles. We conclude that OPLA scaffolds provide a promising environment for bone substitutes using human JPC.     

Vertical fiber-to-waveguide coupling using adapted fibers with an angled facet fabricated by a simple molding technique

Vertical coupling between silicon-on-insulator waveguides and optical fibers is achieved using adapted fibers with an angled facet. The proposed coupling scheme is demonstrated for waveguides containing uniform one-dimensional grating couplers. A coupling efficiency of 32% and a 1 dB bandwidth of 32 nm are measured at a wavelength of 1550 nm. We demonstrate single-step fabrication of these fibers using a simple molding technique.     

An investigation of haptic feedback effects in telepresent microassembly

New manufacturing techniques are being continuously developed to facilitate producing micro parts and products. However, the assembly of these parts becomes very demanding when it comes to manual assembly, e.g. the assembly of prototypes or small batch sizes. The implementation of telepresence technology for such a task segment is a promising solution. This paper discusses the influences of haptic feedback for telepresent micro assembly. Furthermore, an experiment for haptic learning is described.     

Numerical simulation of the collision of two microdroplets with a pseudopotential multiple-relaxation-time lattice Boltzmann model

Collisions of two equally sized liquid microdroplets in gaseous phase are numerically studied by the lattice Boltzmann method (LBM). The multiphase formulation adopted is a pseudopotential model with improved treatment of the equation of state and force incorporation which is then coupled with the multiple-relaxation-time scheme. That allows a detailed investigation into microdroplet collisions characterized by high-density ratios as well as by relevant inertial effects. Simulations related to a wide range of flow parameters (e.g. Weber and Reynolds numbers) are reported, in order to embrace all the collisional regimes presented in previous experimental studies. From surface tension-driven coalescence (both inertial and viscous coalescence have been examined) to catastrophic break-up with the formation of children microdroplets, the simulations demonstrate that the LBM correctly reproduces the collision dynamics and the final outcomes in almost all the regimes. Different break-up mechanisms like end-pinching and capillary wave-induced break-up have been observed. Finally, the initial stages of the inertia-dominated head-on collision process have been studied, showing once more the effectiveness and reliability of this multiphase LBM implementation.     

Synthesis gas production from methane and propane in a miniaturized GlidArc reformer

The current paper focuses on the miniaturization and utilization of the GlidArc^® principle for the reforming of fuel gases (such as methane and propane) to synthesis gas (H₂ + CO). The reforming characteristics and optimal operating conditions to achieve maximum synthesis gas yield were determined. Parametric screening studies were performed with different (i) atomic ratios of oxygen to carbon (O/C) in the range from 1 to 2, (ii) and feed flow rates from 2 to 10 L/min using alternating current voltage to produce the plasma in the reactor, which was varied from 2.8 to 4.6 kV. A Higher synthesis gas ratio of H₂/CO ≈ 2.35 was achieved when methane was processed at O/C = 1 in comparison with propane (H₂/CO ≈ 1.52).     

Simultaneous Estradiol and Levonorgestrel Transdermal Delivery from a 7-day Patch: In Vitro and In Vivo Drug Deliveries of Three Formulations

ABSTRACT

A new drug-in-adhesive transdermal patch was developed to deliver both estradiol and levonorgestrel through the skin over a 7-day period, but at different rates. This report elucidates the in vitro and in vivo biopharmaceutical studies that were necessary during the development of this product. Three test patches had to be manufactured, all delivering estradiol at the same rate, but delivering levonorgestrel at three different rates so that a levonorgestrel dose response could be studied in the clinic. An in vitro hairless mouse skin model (HMS) using modified Franz diffusion cells was used to select the test products delivering levonorgestrel in the order of 1:2:3. HMS experiments also demonstrated that the presence of estradiol did not affect the flux of levonorgestrel. Two in vivo studies in postmenopausal women showed that at steady state (four weeks of once-weekly dosing) the three test products all delivered estradiol at comparable rates. Similarly, the levonorgestrel deliveries for the three test products were in the order expected. The target fluxes of both drugs were achieved in these three test products by varying the drug loads and patch size. That this approach was successful is evidence of the value of using the HMS penetration experiments in transdermal product development and should provide useful insights for other formulations having to develop complex systems. One of the test products is now marketed as Climara Pro^TM.     

Natural Numbers in Trans-classic Systems

PART I

Mathematico-Philosophical Prolegomena

Part II of this essay was written before Part I and offered to the Third Annual Symposium of the American Society for Cybernetics as a topic of discussion. However, owing to unforeseen circumstances, the paper was not presented at the Symposium. This turned out to be a blessing in disguise. In order to conform to the time limit for oral presentation Part II was written in a highly condensed manner and there was no opportunity to elaborate on the general epistemological aspect which served as the starting point for the intended confrontation between natural numbers and structural systems of higher complexity than our traditional logic offers. We are determined to make up for this omission in Part I because we believe that the theoretical goal of Part II will be better understood if the present author clarifies his attitude toward the basic concept of organism and its mathematical treatment in cybernetic research.     

New oxygen evolution anodes for metal electrowinning: investigation of local physicochemical processes on composite electrodes with conductive atomic force microscopy and scanning electrochemical microscopy

Atomic force microscopy (AFM), conductive atomic force microscopy (CAFM) in air, and scanning electrochemcial microscopy (SECM) in 2 M H₂SO₄ have been used to investigate model composite electrodes obtained by pressing sieved MnO₂ particles into a Pb matrix. These model electrodes shall resemble new composite electrodes produced by coldspraying and currently being tested for Zn electrowinning. CAFM showed a very uneven distribution of the current path through the matrix electrode with the highest currents measured at the MnO₂/Pb domain boundary. SECM images in the substrate-generation/tip-collection mode in vertical and horizontal planes could show spatial concentration distribution of H⁺, O₂ and H₂O₂ that could be evaluated qualitatively despite interfering turbulent convection due to raising gas bubbles. There is a concentration overvoltage due to deviations of the H⁺ and O₂ concentration close to the surface from the bulk value. It amounts to about 40–50 mV for both compounds. H₂O₂ is formed as an intermediate and is consumed at the MnO₂ catalyst particles.