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1.
The degradation problem of petroleum products arises since hydrocarbon acts as an excellent food source for a wide variety of microorganisms. Microbial activity leads to unacceptable level of turbidity, corrosion of pipeline and souring of stored product. The present study emphasizes the role of Bacillus cereus ACE4 on degradation of diesel and its influence on corrosion of API 5LX steel. A demonstrating bacterial strain ACE4 was isolated from corrosion products and 16S rRNA gene sequence analysis showed that it has more than 99% similarity with B. cereus. The biodegradation and corrosion studies revealed that B. cereus degraded the aliphatic protons and aromatic protons in diesel and is capable of oxidizing ferrous/manganese into oxides. This is the first report that discloses the involvement of manganese oxidizer B. cereus ACE4 on biodegradation of diesel and its influence on corrosion in a tropical country pipeline. 相似文献
2.
3.
When materials such as Armco iron, titanium etc., are subject to impact it can be observed that two basic inelastic processes
take place – slip and deformation twinning. Of these processes, inelasticity associated with the slip mechanism has received
considerable attention. For example, Zerilli and Armstrong (1988) modeled the Taylor impact test for a variety of materials
using traditional plasticity theories. They found that there was a significant discrepancy between the theoretical and experimental
results for some materials. They attributed this to the fact that they had neglected deformation twinning in their models.
Subsequent metallurgical studies have indicated that twinning had indeed taken place in these materials.
In this study, we focus on the inelastic processes solely due to deformation twinning (i.e., neglecting slip). We model these
processes using the approach of Rajagopal and Srinivasa (1995, 1997) and Srinivasa et al., (1997), the results of which are
briefly summarized in section 2.1. In order to better understand the twinning process, we study the Taylor impact test for
a 2-D slab under the assumption that only deformation twinning takes place and solve the governing dynamical equations by
using the finite element method. The results show that the twinned zone is concentrated near the point of impact and indeed
it contributes significantly to the overall permanent shape change due to the impact. 相似文献
4.
5.
This article reports the effect of three cobalt carboxylates—cobalt stearate (CoSt3), cobalt palmitate (CoPal3), and cobalt laurate (CoLau3)—on the thermo‐oxidative degradation of low‐density polyethylene (LDPE) films prepared by sheeting process. The carboxylates were blended with LDPE in the concentration range of 0.05–0.2% (w/w). The degradation was monitored by techniques such as FTIR spectroscopy, change in the mechanical properties (tensile strength and elongation at break), viscometry, surface electron microscopy, melt flow index measurements, and apparent density measurements. Studies indicate that films containing these additives are highly susceptible to thermo‐oxidative degradation. Oxygen containing functionalities such as carbonyl and vinyl species are generated on the surface of polyethylene because of thermo‐oxidation, as indicated by FTIR studies. This oxidative process is accelerated in the presence of cobalt carboxylates. The degradation of LDPE was found to increase proportionally with concentration as well as with increasing chain length of the cobalt carboxylate, and follow the order CoSt3 > CoPal3 > CoLau3. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3758–3765, 2007 相似文献
6.
[60]Fullerene (C60) was mono-substituted with well-defined poly(methyl methacrylate) (PMMA-b-C60) using the atom transfer radical polymerization (ATRP) technique. The self-assembly behaviors of PMMA-b-C60 in ethyl acetate (EA) and decalin mixtures were studied using laser light scattering (LLS) and transmission electron microscopy (TEM). Homogeneous solutions of PMMA-b-C60 can be obtained in the solvent mixtures containing more than 40 wt% EA, where the molar ratio of decalin to EA is close to 1. For each solvent mixture, unimers coexist with micelles and large aggregates. The sizes of PMMA-b-C60 micelles and aggregates are independent of polymer concentration, confirming that they are produced via the closed association mechanism. For the various solvent mixtures, the weight-averaged molecular weights, Mw of the PMMA-b-C60 aggregates range from 4.1×107 to 12.5×107 g/mol. The hydrodynamic radii of the large aggregate, Rh, vary from 90 to 136 nm, while the z-averaged radii of gyration, Rg, range from 210 to 311 nm. The Rg/Rh value for each solvent mixture is ∼2.3, which is independent of decalin contents in the mixed solvents. The morphological study using the transmission electron microscope suggests that the large aggregates are composed of porous large compound micelles (LCM) in solution. 相似文献
7.
A. R. Usha Devi A. K. Rajagopal Sudha H. S. Karthik J. Prabhu Tej 《Quantum Information Processing》2013,12(12):3717-3723
Classical and quantum world views differ in peculiar ways. Understanding decisive quantum features—for which no classical explanation exist—and their interrelations is of foundational interest. Moreover, recognizing non-classical features carries practical significance in information processing tasks as it offers insights as to why quantum protocols work better than their classical counterparts. We focus here on two celebrated notions of non-classicality viz., negativity of P phase–space representation and entanglement in symmetric multiqubit systems. We prove that they imply each other. 相似文献
8.
Summary The mechanics of flowing granular materials such as coal, sand, metal ores, etc., and their flow characteristics have received considerable attention in recent years as it has relevance to several important technological problems. In a number of instances, these materials are also heated prior to processing, or cooled after processing. The governing equations for the flow of granular materials, taking into account the heat transfer mechanism by conduction, are derived using a continuum model (cf. Goodman and Cowin [1], [2], Rajagopal and Massoudi [3]). For a fully developed flow of these materials down an inclined plane, the equations reduce to a system of coupled non-linear ordinary differential equations. The resulting boundary value problem is solved numerically and the results are presented for cases where the viscosity and thermal conductivity are assumed to be functions of the volume fraction. It is shown that the equations admit multiple solutions for certain values of the parameters.List of symbols
D
Symmetric part of the velocity gradient
-
K
thermal conductivity
-
L
velocity gradient
-
T
Cauchy stress tensor
-
b
body force
-
h
characteristic height
-
q
heat flux
-
r
radiating heat
-
u
velocity vector
-
angle of inclination of the inclined plane with the horizontal
-
specific internal energy
-
distributed mass density
-
temperature
-
volume fraction
-
bulk mass density 相似文献
9.
J. B. Mandal B. Bandyopadhyay B. Ghosh H. Rajagopal A. Sequeira J. V. Yakhmi 《Journal of Superconductivity》1996,9(2):253-257
Rietveld analysis of powder neutron diffraction pattern recorded on Sr-based 1201-phase superconductor (T
c
=53 K), (Hg0.7Cr0.3)Sr2CuO4+ shows that the oxygen atoms at O(3) site are disordered atx=y=0.3712. This fourfold split site has a total combined occupancy of 80% and is the only occupied site in the (Hg, Cr)O plane. 相似文献
10.
This paper presents an overview on the application of FE simulation as a virtual manufacturing tool in designing manufacturing processes for precision parts. The processes discussed include forging, sheet metal forming and hydroforming. Determination of reliable input parameters to simulate a process is a key element in successful application of process simulation for process design in all the mentioned areas. These issues are discussed in detail. Practical examples of application of FE simulation are presented for improvement of the existing metal forming process and/or designing new metal forming process for manufacturing discrete precision parts in forging, sheet metal forming and hydroforming. 相似文献