Branes Ending On Branes In A Tachyon Model

In a tachyon model proposed by Minahan and Zwiebach and derived in the boundary string field theory, we construct various new solutions which correspond to nontrivial brane configurations in string theory. Our solutions include Dp-D(p-2) bound states, (F, Dp) bound states, string junctions, D(p-2)-branes ending on a Dp-brane, D(p-2)-branes suspended between parallel Dp-branes and their non-commutative generalizations. We find the Bogomol'nyi bounds and the BPS equations for some of our solutions, and check the physical consistency of our solutions with the D-brane picture by looking at the distributions of their energies and RR-charges in space. We also give conjectures for a few other brane configurations.Comment: 19 pages, LaTeX, minor corrections and references adde

Large branes in AdS and their field theory dual

Recently it was suggested that a graviton in $AdS_5 \times S^5$ with a large momentum along the sphere can blow up into a spherical D-brane in $S^5$. In this paper we show that the same graviton can also blow up into a spherical D-brane in $AdS_5$ with exactly the same quantum numbers (angular momentum and energy). These branes are BPS, preserving 16 of the 32 supersymmetries. We show that there is a BPS {\it classical} solution for SYM on $S^3\times R$ with exactly the same quantum numbers. The solution has non-vanishing Higgs expectation values and hence is dual to the large brane in AdS.Comment: 20 pages, 6 figures, minor change

Temperature and Concentration Distributions in Fixed-bed Catalytic Reactors : Comparison of Calculated with Experimental Results

Fixed-bed catalytic reactors are most widely used for vapor-phase reactions catalyzed by solid particles. Although theoretical studies concerned with the design method have been extensively performed, few systematic experimental substantiations have been presented. The purpose of this paper is to obtain the necessary data for the reactor design and to evaluate the accuracy of the design method. The radial temperature profiles and the mean conversions at various catalyst heights were measured in a 5.0 cm I.D. reactor where the hydrogenation of benzene takes place on a nickel-kieselguhr catalyst. The basic design data, the rate of reaction and the heat transfer characteristics in a fixed bed were also presented. A numerical design method used here is similar to those developed by Smith and Walas with suitable modification. Profiles of temperature and conversion predicted by the numerical method were in good agreement with the experimental data

Studies on the Flow Patterns of Liquids in a Cylindrical Mixing Vessel, Over a Wide Range of Reynolds Number

The flow patterns of liquids agitated in a cylindrical mixing vessel without baffles were measured by a photographic method, ranging from laminar to so-called transitional flow. The authors are now able to discuss the flow pattern of the liquid and the discharge performance of the impellers over a wide range of Reynolds number, combined with the previous results published for the turbulent flow range. Some of the experimental results are shown in Figs. 6, 7, 8 and 10. The authors discovered the following results on the velocity distribution of the liquid : In the range of very small Reynolds number, the liquid velocity is considerably high only in the neighbourhood of the impeller and decreases abruptly with the distance from the impeller. On the other hand, in the range of high Reynolds number, secondary circulation flow occurs as shown in Fig. 9 and also the flow becomes turbulent, so that the liquid attains considerable velocity even at a distance from the impeller by the transmission of momentum, and the velocity distribution is considerably unified throughout the vessel. Concerning the discharge flow from the tip of the impeller blades which causes the secondary circulation, the non-dimensional quantities, Nq₁, and Nᴘ/Nq₁, are defined, as in the previous report. These values were calculated and the characteristic curves of discharge performance were obtained for various types of impellers (refer to Table 1), as shown in Fig. 12. Furthermore, the relations between flow pattern, discharge performance and power consumption (Nᴘ-Rₑ relation) were discussed

Flow Patterns of Liquids in a Cylindrical Mixing Vessel with Baffles

The velocity distribution of a liquid in a cylindrical mixing vessel with flatplate-baffles was measured by a method similar to that adopted in the case without baffles. Some of the experimental results are shown in Figs. 3, 4, 5, 6, 7, 8 and 9. Variations of the liquid velocity distribution caused by inserting baffle-plates are shown in Fig. 10. Obviously, the insertion of baffle-plates reduces the circulation flow around the impeller axis (the tangential component vₜ of liquid velocity) and increases the circulation flow in the vertical direction. The discharging performance of various impellers is represented by the ratio NₚB/Nq₁, which is the dimensionless factor corresponding to the relative power required for the unit quantity of discharge. The comparisons of these ratios for various impellers are shown in Table 3, together with those for the non-baffled condition. It is to be noted that, in spite of a considerable increase in Nq₁ the circulation efficiency of the agitators is eventually lowered by inserting baffle-plates. Furthermore, the power consumption in the neighbourhood of the impeller (Nᴘᵢₚₘ) was calculated and compared with that consumed in the outer region of the vessel (ΔNₚ) as shown in Table 4, It may be considered that the improvement in the circulating capacity is accomplished by the proper design of the baffle-plates

Kinetics of Heterogeneous Liquid Phase Reaction : Simultaneous Mass Transfer and Chemical Reaction

The solution of the over-all rate of reaction for a steady state mass transfer accompanied by a (l+ｫ)-th order irreversible reaction was derived by applying an approximate concentration distribution model for the heterogeneous liquid phase reaction which might proceed in a diffusion film and homogeneous mixed bulk liquid of finite volume. The numerically calculated diagrams showing the functional relation between the over-all rate of reaction and the reaction conditions such as the resistances to diffusion and chemical reaction, liquid volume and the inter facial contact area, etc. were presented. The authors made clear the conditions for the five states of over-all reaction rate which were different in comparative magnitude in the resistances to diffusion and chemical reaction, and interpreted the various types of rate controlling step by comparing the reaction conditions and the concentration distribution of reactants both in diffusion film and bulk liquid

Enzymatic one-step ring contraction for quinolone biosynthesis.

The 6,6-quinolone scaffolds on which viridicatin-type fungal alkaloids are built are frequently found in metabolites that display useful biological activities. Here we report in vitro and computational analyses leading to the discovery of a hemocyanin-like protein AsqI from the Aspergillus nidulans aspoquinolone biosynthetic pathway that forms viridicatins via a conversion of the cyclopenin-type 6,7-bicyclic system into the viridicatin-type 6,6-bicyclic core through elimination of carbon dioxide and methylamine through methyl isocyanate

Improvement of slippage and wrinkling of transporting webs using micro-grooved rollers

We describe an entirely new method of improving the slippage between web and roller. First, the concept of a micro-grooved roller is introduced, and then a theoretical model for estimating the slip onset velocity under the transport of web by the micro-grooved roller is formulated. The predicted results are compared with the experimental data to verify the applicability of the prediction model of slippage. Moreover, the web-wrinkling condition, which is in a trade-off relationship with the slippage condition, is also considered in the model. From the theoretical and experimental results, it is confirmed that the optimized micro-grooved roller is very effective in improving the slippage and wrinkling of thin web under the high-speed transport with low tension at the actual production line