Prostaglandins suppress an outward potassium current in embryonic rat sensory neurons

One of the challenges in understanding ciliary and flagellar motility is determining the mechanisms that locally regulate dynein-driven microtubule sliding. Our recent studies demonstrated that microtubule sliding, in Chlamydomonas flagella, is regulated by phosphorylation. However, the regulatory proteins remain unknown. Here we identify the 138-kD intermediate chain of inner arm dynein I1 as the critical phosphoprotein required for regulation of motility. This conclusion is founded on the results of three different experimental approaches. First, genetic analysis and functional assays revealed that regulation of microtubule sliding, by phosphorylation, requires inner arm dynein I1. Second, in vitro phosphorylation indicated the 138-kD intermediate chain of I1 is the only phosphorylated subunit. Third, in vitro reconstitution demonstrated that phosphorylation and dephosphorylation of the 138-kD intermediate chain inhibits and restores wild-type microtubule sliding, respectively. We conclude that change in phosphorylation of the 138-kD intermediate chain of I1 regulates dynein-driven microtubule sliding. Moreover, based on these and other data, we predict that regulation of I1 activity is involved in modulation of flagellar waveform.     

Intrapelvic migration of a total hip prosthesis in rheumatoid arthritis

The authors discuss the risk of mechanical loosening and protrusion of a cemented endoprosthesis of the hip joint after operation which is one of the few possibilities of palliative treatment in patients with rheumatoid arthritis. They deal in particular with specific features of surgical approaches whereby they select a modified method described by Eftekhar which makes it possible to resolve even severe grades of intrapelvic migration of the socket of a total endoprosthesis. The authors discuss possible complications which can be prevented if the relationship of intrapelvic structures to the protruded prosthesis is elucidated before operation. In a group of 1268 patients operated there were three with intrapelvic migration of a total endoprosthesis of the hip joint.     

A Dynamic Programming Model for Determining Continuous-Caster Configurations

In the steel industry the continuous casting machine, or caster, can be used to eliminate a number of processing steps associated with the traditional steel production sequence from ingot through blooms to finished product. A given continuous caster can produce only a small number of bloom thicknesses, which creates a problem for selecting those continuous-caster configurations which would maximize caster utilization. A dynamic programming model was developed to assist Bethlehem Steel personnel to determine that set of caster configurations which would maximize the cast bloom tonnage that could be processed through one of the finishing mills. Without the aid of such a model, selecting the highest productivity options presents a difficult exercise because of two conflicting considerations: (1) as the number of caster-produced bloom thicknesses increases, the caster setup time and configuration complexity increase; and (2) as the number of thicknesses decreases, less cast tonnage can be processed through the finishing mill because of reheat-furnace and cooling-bed limitations. The model results were transmitted to plant management and are being used in conjunction with other information to determine the most economic configuration.     

High-surface-area organic matrix tris(aza)pentacene supported platinum nanostructures as selective electrocatalyst for hydrogen oxidation/evolution reaction and suppressive for oxygen reduction reaction

Developing a Pt-based electrocatalytic material able to selectively catalyze hydrogen oxidation (HOR) while supressing oxygen reduction (ORR) is beneficial for durability of the fuel cells. Namely, degradation of carbon supported Pt particles is dramatically influenced by the unwanted ORR enrolling at the anode due to the air penetration during start-up/shut-down events. We present an organic matrix tris(aza)pentacene (TAP), which belongs to π-functional materials with ladder-like conjugated nitrogen-containing units, as the support for Pt to form a “smart” fuel cell anode able to selectively catalyze HOR and to suppress ORR. “Switching-on/off” of the composite material activity is provided by reversible reduction/oxidation of the TAP in the low potential region which provokes TAP - H_xTAP transition. Conductivity of the reduced H_xTAP enables supported Pt particles to effectively run HOR. In contrast, restricted conductivity of oxidized TAP analogue leads to the substantial drop in the ORR activity with respect to benchmark Pt/C catalyst.     

Serial and parallel Si, Ge, and SiGe direct-write with scanning probes and conducting stamps

Precise materials integration in nanostructures is fundamental for future electronic and photonic devices. We demonstrate Si, Ge, and SiGe nanostructure direct-write with deterministic size, geometry, and placement control. The biased probe of an atomic force microscope (AFM) reacts diphenylsilane or diphenylgermane to direct-write carbon-free Si, Ge, and SiGe nano and heterostructures. Parallel direct-write is available on large areas by substituting the AFM probe with conducting microstructured stamps. This facile strategy can be easily expanded to a broad variety of semiconductor materials through precursor selection.     

Total oxidation of volatile organic compounds on Au/Ce–Ti–O and Au/Ce–Ti–Zr–O mesoporous catalysts

Cerium–titanium mixed oxides and mesoporous cerium-modified titanium and cerium-modified titanium–zirconium mixed oxides were synthesized in order to obtain active support for gold volatile organic compound (VOC) oxidation catalysts. Ce–Ti mixed oxides were synthesized by sol–gel method. Mesoporous TiO₂ and Ti–Zr mixed oxides were prepared through the surfactant templating technique. Gold was loaded on supports by deposition-precipitation method. The catalysts were characterized by thermal analysis, XRD, N₂ analysis, TPR, DR/UV–vis and IR. The results evidenced the beneficial role of ceria modifying additive in decreasing the degree of crystallinity of mesoporous support and its particle size. A high degree of synergistic interaction between ceria and mesoporous oxide was observed. H₂-TPR revealed that the reducibility of the catalysts is greatly enhanced in the presence of gold. Considering the light off temperature, the activity of Au/mesoporous cerium-modified titanium oxide is particularly interesting for VOC oxidation comparatively to the same catalysts with a classical support. The gold particles would be more dispersed and stable. However, the sample Au/mesoporous cerium-modified titanium–zirconium mixed oxide is less interesting for VOC oxidation, particularly for toluene oxidation whose activity depends essentially on the adsorption of toluene molecule.     

Magnetic Levitation Tribometer: A Point-Contact Friction

We developed a new magnetic levitation tribometer (MLT) to study point-contact friction via pendulum method. The device allows us to carry out fast and accurate point-contact measurement of friction between a pair of materials. The MTL parameters were found with the help of test experiments with the steel ball / glass plate pair. The friction coefficient values are coherent with the results known in the literature (Serway and Beichner in Physics for scientists and engineers, 5th edn, Saunders College Publishing, Orlando, 2000). The proposed MLT technique at loads lower than \(10^{-3}\) N is very promising for non-destructive investigation of frictional properties of organic monolayers.     

Assigning slabs to orders: an example of appropriate model formulation

An important problem for a steel company is the assigning of slabs, i.e. semi-finished rectangular pieces of steel, to customer orders. Due to its discrete nature, the prolem can be formulated as a zero-one integer programming problem; however, real-world problems are too large (12,000–16,000 zero-one variable) to be solved exactly in a reasonable amount of computer time. In this paper we present a transportation formulation for this problem that can be efficiently solved using a network code of Bertsekas. Then, using rounding heuristics, the transportation solution can be transformed into a practical solution. An example is used to illustrate this approach. Empirical results indicate that excellent (low-cost) practical solutions can be generated for large-scale (300 orders and 3000 slabs) problems in less than 1 min on a 386 PC (25 MHZ).