Naphtha Reduction of Iron Ores to Sponge Iron in Continuous Vertical Reactor

The development of a process of sponge iron production by naphtha, a petroleum by-product, in a continuous 90mm I.D. vertical reactor is discussed. The process, the equipment and the operational parameters, the results of the campaigns with various iron ores pellets are described. Sized iron ore fines from two deposits were directly reduced by petroleum naphtha to sponge iron at a temperature of about 1000 deg. C. maintaining naphtha injection at different controlled flow rates. The movement of solids in the reactor column was also controlled to obtain predetermined residence times.producing 70-100 kgs of sponge iron per day. Under optium conditions 98 percent metallization was obtained. The results are discussed in the light of efficiency of the reductant and the economics of the process

Effective and Efficient Algorithms for Concise Range Queries

With the advance of wireless communication technology, it is quite common for people to view maps or get related services from the handheld devices, such as mobile phones and PDAs. Range queries, as one of the most commonly used tools, are often posed by the users to retrieve needful information from a spatial database. However, due to the limits of communication bandwidth and hardware power of handheld devices, displaying all the results of a range query on a handheld device is neither communication efficient nor informative to the users. This is simply because that there are often too many results returned from a range query. In view of this problem, we present a novel idea that a concise representation of a specified size for the range query results, while incurring minimal information loss, shall be computed and returned to the user. Such a concise range query not only reduces communication costs, but also offers better usability to the users, providing an opportunity for interactive exploration. The usefulness of the concise range queries is confirmed by comparing it with other possible alternatives, such as sampling and clustering. Unfortunately, we prove that finding the optimal representation with minimum information loss is an NP-hard problem. Therefore, we propose several effective and nontrivial algorithms to find a good approximate result. Extensive experiments on real-world data have demonstrated the effectiveness and efficiency of the proposed techniques

Bose-Einstein condensates with attractive 1/r interaction: The case of self-trapping

Amplifying on a proposal by O'Dell et al. for the realization of Bose-Einstein condensates of neutral atoms with attractive $1/r$ interaction, we point out that the instance of self-trapping of the condensate, without external trap potential, is physically best understood by introducing appropriate "atomic" units. This reveals a remarkable scaling property: the physics of the condensate depends only on the two parameters $N^2 a/a_u$ and $\gamma/N^2$, where $N$ is the particle number, $a$ the scattering length, $a_u$ the "Bohr" radius and $\gamma$ the trap frequency in atomic units. We calculate accurate numerical results for self-trapping wave functions and potentials, for energies, sizes and peak densities, and compare with previous variational results. As a novel feature we point out the existence of a second solution of the extended Gross-Pitaevskii equation for negative scattering lengths, with and without trapping potential, which is born together with the ground state in a tangent bifurcation. This indicates the existence of an unstable collectively excited state of the condensate for negative scattering lengths.Comment: 7 pages, 7 figures, to appear in Phys. Rev.

Anomalous Thermoelectric power of over-doped Bi2Sr2CaCu2O8 superconductor

Temperature dependence of thermoelectric power S(T) of three differently processed Bi2Sr2CaCu2O8 (Bi2212) samples, viz. as-processed melt quenched (Bi2212-MQ), 6000C N2-annealed (Bi2212-N2) and 6000C O2-annealed (Bi2212-O2) is reported here. All the samples possess single-phase character and their superconducting transition temperatures (TcR=0) are 85 K, 90 K and 72 K respectively for Bi2212-MQ, Bi2212-N2 and Bi2212-O2. While Bi2212-MQ and Bi2212-N2 samples are in near optimum doping regime, Bi2212-O2 is an over-doped sample. TcS=0 values obtained through S(T) data are also in line with those deduced from the temperature dependence of resistance and DC magnetization. Interestingly, S(T) behaviour of the optimally-doped Bi2212-MQ and Bi2212-N2 samples is seen to be positive in whole temperature range, it is found negative for the over-doped Bi2212-O2 sample above TcS=0. These results have been seen in the light of the recent band structure calculations and the ensuing split Fermi surface as determined by angle-resolved photoelectron spectroscopy (ARPES).Comment: 11 Pages Text + Figs: comments welcome ([email protected]

Supergravity Radiative Effects on Soft Terms and the μ\mu Term

We compute quadratically divergent supergravity one-loop effects on soft supersymmetry-breaking parameters and the $\mu$ term in generic hidden sector supergravity models. These effects can significantly modify the matching condition for soft parameters at the Planck scale and also provide several new sources of the $\mu$ term which are naturally of order the weak scale. We also discuss some phenomenological implications of these effects, particularly the violation of the scalar mass universality which may lead to dangerous FCNC phenomena, and apply the results to superstring effective supergravity models.Comment: 12 pages, REVTEX. One reference is adde

Use of Geotextiles in Low Volume Roads — A Case Study

The application of geotextiles has been well accepted as a construction material in Civil engineering works. However, in India, the utility of geotextiles is very limited to particular areas of application in Civil Engineering such as highways, railways and irrigation projects etc. On an experimental basis, these fabrics have been used as an intermediate layer between subgrade and subbase to serve as a separation and drainage layer in a road constructed on soft subgrade soil. The main objective of field trials was to study the need, relevance and the relative efficacy of the use of geotextiles as compared to the use of conventional techniques in the construction and maintenance of road pavements on soft subgrades. The surface characteristics of different test sections were evaluated in terms of riding quality, rut depth and transverse/longitudinal slope variance. The structural adequacy of different specifications were determined using Benklemen Beam deflection tests. Based on the detailed data analysis, it is concluded that the geosynthetics are an effective substitute for conventional blanket courses as a separator with the added benefit that they ensure more effective subsurface drainage of the pavement compared to conventional blanket courses

Distinct levels in the nanoscale organization of DNA-histone complex revealed by its mechanical unfolding

Mechanical unfolding of nanoscale DNA-histone complex, using an atomic force microscope, shows a stepwise disassembly of histones from the nucleosome. A quantitative analysis of the rupture jump statistics and the length released per jump reveals insights into the possible histone contacts within the octamer complex. The measured ruptures correlate with the breakage of multiple contacts that stabilize the histone octamer. These results provide a mechanistic basis by which stepwise disassembly of histone proteins may result from an external force exerted by the adenosinetriphosphate (ATP) dependent chromatin remodeling machines to access regulatory sites on DNA

Morphological features of liver effect in patients with chronic hepatitis B with HIV-coinfection

The article presents modern views on morphological disturbances in liver tissue at HBV/HIV patients. It was shown that "matte-glass-like" hepatocytes, inflammatory cell lymphocytic infiltrate of varying degrees and liver fibrosis are specific signs of HBV/HIV patients. Specific morphological signs of liver damage in co-infected patients confirm that HIV-infection worsens histological structure as well as functional balance. Therefore, development of pathohistology method of diagnostics becomes more and more necessary in patients with complicated liver injuries. New findings can give opportunity for early screening HBV-infected patients for HIV-markers, prescribing antiviral treatment at early stages. The research will build new approach for avoiding fast fibrogenesis

SUSTAINED RELEASE DELIVERY OF REPAGLINIDE BY BIODEGRADABLE MICROSPHERES

The primary objective of the present study was to prepare repaglinide microspheres for the sustained delivery of the drug for better patient care in the management of diabetics. The biodegradable microspheres of repaglinide is prepare using poly (lactic-co-glycolic acid) (PLGA) by emulsion solvent evaporation technique. The microspheres are prepared with different drug-to-carrier ratios and considering other variables (i.e. solvent, surfactant and stirrer speed) as well. The evaluation of microspheres prepared are perform on the basis of various parameters  like particle size, percentage yield, drug entrapment efficiency, surface morphology, drug-polymer interaction (FT-IR study), in vitro drug release kinetics and stability studies. SEM reveals that microspheres are spherical and has nearly smooth surface morphology. The percentage yield and drug entrapment efficiency is quite well for all the formulations. FT-IR spectra show that there is no chemical interaction between the drug and the polymer. The in vitro release study data shows that the repaglinide release from all the formulations are slow and sustained upto 7days. The various kinetic equations indicate that the in vitro drug release is of zero order release with initial burst from repaglinide microspheres. There is no appreciable difference is observed in the stability study observations