| 1. |
- Bahrami, Fariba, et al.
(författare)
-
Analysis of a thermosyphon using a Mandelstam condition
- 2016
-
Ingår i: Proceedings of the Institution of Civil Engineers. - : Thomas Telford Ltd.. - 1755-0777 .- 1755-0785. ; 169:1, s. 29-39
-
Tidskriftsartikel (refereegranskat)abstract
- The characteristics of a thermally forced connected-vessel thermosyphon operating in an oscillatory mode have been determined using analytical techniques, the outcome of which is compared with results obtained by numerical integration of the governing equations. From a previous investigation it was known that adequate phase-plane representations of the limit cycles associated with oscillations could be obtained if the vessel-volume ratio was sufficiently small. This study aims at demonstrating how this constraint on the vessel volumes can be relaxed by prescribing a Mandelstam condition, that is, by postulating that the total heat content of the system remains conserved during the rapid phases of the oscillation. It was concluded that incorporating this Mandelstam condition in the analysis had the highly beneficial consequence that good analytical results could be obtained for much larger values of the vessel-volume ratio than those previously permitted.
|
|
| 2. |
- Bahrami, Fariba, et al.
(författare)
-
Existence of energy maximizing vortices in a three-dimensionalquasigeostrophic shear flow with bounded height
- 2010
-
Ingår i: Nonlinear Analysis. - : Elsevier. - 1468-1218. ; 11:3, s. 1589-1599
-
Tidskriftsartikel (refereegranskat)abstract
- The existence of an energy maximizer relative to a class of rearrangements of agiven function is proved. The maximizers are stationary and stable solutions of thequasigeostrophic equation, which governs the time evolution of large-scale threedimensionalgeophysical flow in a vertically bounded domain. The background flow isunidirectional, with linear horizontal shear. The theorem proved implies the existence of afamily of stationary and stable vortices that rotate in the same direction as the backgroundshear. It extends an earlier theorem by Burton and Nycander, which is valid for a verticallyunbounded domain.
|
|
| 3. |
- Bahrami, Fariba, et al.
(författare)
-
Existence of energy minimizing vortices attached to a flat-top seamount
- 2007
-
Ingår i: Nonlinear Analysis. - : Elsevier BV. - 1468-1218. ; 8, s. 288-294
-
Tidskriftsartikel (refereegranskat)abstract
- The existence of an energy minimizer relative to a class ofrearrangements of a given function is proved. The minimizers are stationary and stable solutions of the two-dimensional barotropic vorticity equation, governing the evolution of geophysical flow over a surface of variable height. The theorem proved implies the existence of a family of stable anticyclonic vortices with cyclonic potential vorticity over a seamount, and a corresponding family of cyclonic vortices with anticyclonic potential vorticity over a localized depression. The seamount is described by a characteristic function (corresponding to a flat top) with arbitrary shape.
|
|
| 4. |
- Bahrami, Fariba, et al.
(författare)
-
Localization and comparative toxicity of methylsulfonyl-2,5-and 2,6-dichlorobenzene in the olfactory mucosa of mice
- 1999
-
Ingår i: Toxicological Sciences. - 1096-6080 .- 1096-0929. ; 49:1, s. 116-123
-
Tidskriftsartikel (refereegranskat)abstract
- Several methylsulfonyl (MeSO2) metabolites formed from chlorinated aromatic hydrocarbons have been identified in human milk, lung, and body fat, as well as in the tissues of Baltic grey seals and arctic polar bears. The tissue localization and nasal toxicity of two methylsulfonyl-substituted dichlorobenzenes (diCl-MeSO2-B), with the chlorine atoms in the 2,5-, and 2,6- positions, were investigated in female NMRI and C57B1 mice. Using tape-section autoradiography, animals dosed i.v. with 14C-labeled 2,5-, or 2,6-(diCl-MeSO2-B) showed a preferential uptake of radioactivity in the olfactory mucosa and the tracheobronchial epithelium. Histopathology showed that 2,6-(diCl-MeSO2- B) is a potent toxicant that induces necrosis in the olfactory mucosa following a single dose as low as 4 mg/kg (i.p. injection), whereas 2,5- (diCl-MeSO2-B) induced no signs of toxicity in the olfactory mucosa at doses as high as 130 mg/kg (i.p. injection). Necrosis of the Bowman's glands was the first sign of 2,6-(diCl-MeSO2-B)-induced toxicity followed by degeneration of the neuroepithelium, which implies that the Bowman's gland may be the primary site of toxicity and degeneration of the neuroepithelium may be a secondary effect. Administration of the parent compounds, 1,3-dichlorobenzene and 1,4-dichlorobenzene, or the chlorinated analog 1,2,3-trichlorobenzene (85, 85, and 105 mg/kg, respectively; i.p. injection), induced no signs of toxicity in the olfactory mucosa. These and previous results suggest that 2,6- positioned chlorine atoms and an electron withdrawing substituent in the primary position is an arrangement that predisposes for toxicity in the olfactory mucosa.
|
|
| 5. |
- Bahrami, Fariba
(författare)
-
Methylsulphonyl-chlorobenzenes and the olfactory system : Comparative toxicity of the 2,5- and 2,6-dichlorinated isomers in mice
- 2000
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Methyl sulphone metabolites of chlorinated aryl hydrocarbons are persistentenvironmental pollutants that can bioaccumulate in animals and humans. Little is known about the toxicological effects of these metabolites and this thesis is an attempt to increase this limited knowledge. Tissue-binding, toxicity and neuro-behavioural effects of methylsulphonyl-2,6dichlorobenzene [2,6-(diCl-MeSO2-B)] and methylsulphonyl-2,5-dichlorobenzene [2,5-(diCl-MeSO2-B)] were examined on mice.Both substances resulted in a strong uptake in the olfactory mucosa (OM). Only 2,6-(diCl-MeSO2-B) induced toxicity in the OM, originating from a primary lesion in the Bowman's glands (BG). An in situ CYP-catalysed activation of 2,6-(diCl-MeSO2-B) seems to occur in the BG giving rise to reactive intermediates which either conjugate with glutathione or induce local toxicity. Subsequent secondary lesions in the OM include: severe degenerationof the neuroepithelium, fibrosis, ossification and polyposis. These effects resulted from a single ip dose and were permanent. Long lasting induction of GFAP in the olfactory bulb (OB) and behavioural deficits were also observed and considered to be caused by damaged olfactory neurons and/or metabolites translocated to the OB. Although the OM was more damaged in male mice, acquisition deficits occurred only in female mice.2,5-(diCl-MeSO2-B) did not induce OM toxicity, GFAP or learning deficits in either sex. However, observed motor activity responses indicate that, although 2,5-(diCl-MeSO2-B) is not olfacto-toxic, it is neuro-toxic.1,3-Dichloro-, 1,4-dichloro- or 1,2,3-trichloro-benzene did not induce damage in the OM indicating that an electron withdrawing substituent in the primary position and 2,6-positioned chlorine atoms is a structural requirement for OM toxicity. Persistent, dose-, time-, tissue- and sex-dependent effects on the olfactory system induced by 2,6-(diCl-MeS2-B) together with the lack of lesions in the OM or brain by 2,5-(diCl-MeSO2-B), makes this chemical pair a reliable and versatile tool for olfactory research.
|
|
| 6. |
- Bahrami, Fariba, et al.
(författare)
-
Persistent Olfactory Mucosal Metaplasia and Increased Olfactory Bulb Glial Fibrillary Acidic Protein Levels Following a Single Dose of Methylsulfonyl-dichlorobenzene in Mice: Comparison of the 2,5- and 2,6-Dichlorinated Isomers
- 2000
-
Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 162:1, s. 49-59
-
Tidskriftsartikel (refereegranskat)abstract
- Histopathology was used to characterize long-term toxic effects in the olfactory system following a single ip dose (4–65 mg/kg) of methylsulfonyl-2,6-dichlorobenzene, (2,6-(diCl-MeSO2-B)), in female NMRI mice. The effects of 2,6-(diCl-MeSO2-B) and its 2,5-chlorinated isomer, (2,5-(diCl-MeSO2-B)), on the levels of glial fibrillary acidic protein (GFAP; a biomarker for neurotoxicity) in different brain regions were examined by an enzyme-linked immunosorbent assay (ELISA). The histopathologic effects of 2,6-(diCl-MeSO2-B) were dose-, time-, and tissue-dependent. At the highest doses (16–65 mg/kg), the initial effect of 2,6-(diCl-MeSO2-B) was necrosis of the Bowman's glands, followed by a sequence of secondary events including degeneration of the olfactory neuroepithelium, repopulation of the basement membrane by a ciliated respiratorylike epithelium, fibrosis and ossification in the lamina propria, formation of bilateral polyps, angiogenesis, and disappearance of nerve bundles. Remodeling was most pronounced in the dorsal meatus of the olfactory mucosa and persisted for the duration of the experiment (46 weeks). A dose-dependent induction of GFAP in the olfactory bulb of mice treated with 2,6-(diCl-MeSO2-B) was observed at all doses examined (16–65 mg/kg). GFAP levels were highest 2 weeks after treatment (eightfold induction at 65 mg/kg) and then gradually decreased to normal within 26 weeks. The 2,5-substituted isomer (65 mg/kg) did not induce GFAP in the olfactory bulb and or toxicity in the olfactory mucosa. In conclusion, a single dose of 2,6-(diCl-MeSO2-B) results in persistent metaplasia and remodeling of the olfactory mucosa, and a long-lasting but transient induction of GFAP in the olfactory bulb. It is proposed that methylsulfonyl-2,6-dichlorobenzene may serve as an experimental tool with a unique ability to produce persistent primary and/or secondary lesions in the olfactory system of mice.
|
|
| 7. |
- Bahrami, Fariba, et al.
(författare)
-
Stability investigation for steady solutions of the barotropic vorticity equation in R-2
- 2013
-
Ingår i: Communications in nonlinear science & numerical simulation. - : Elsevier BV. - 1007-5704 .- 1878-7274. ; 18:3, s. 541-546
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the p-norm stability for vortices of geophysical flows over a surface of variable height that are strict maximizers of the kinetic energy relative to all isovortical flows. In this note, stability means nonlinear stability in the p-norm on the space of vorticity.
|
|
| 8. |
|
|
| 9. |
- Carlsson, Carina, et al.
(författare)
-
Olfactory mucosal toxicity screening and multivariate QSAR modeling for chlorinated benzene derivatives
- 2004
-
Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 78:12, s. 706-715
-
Tidskriftsartikel (refereegranskat)abstract
- The olfactory mucosa (OM) is an important target for metabolism-dependent toxicity of drugs and chemicals. Several OM toxicants share a 2,6-dichlorinated benzene structure. The herbicides dichlobenil (2,6-dichlorobenzonitrile) and chlorthiamide (2,6-dichlorothiobenzamide) and the environmental dichlobenil metabolite 2,6-dichlorobenzamide all induce toxicity in the OM following covalent binding in the Bowmans glands. In addition, we have shown that 2,6-dichlorophenyl methylsulfone targets the Bowmans glands and is probably the most potent OM toxicant so far described. These findings suggest that the 2,6-positioning of chlorines in combination with an electron-withdrawing group in the primary position of the benzene ring is an arrangement that facilitates OM toxicity. This study examined the physicochemical characteristics of the 2,6-dichlorinated OM toxicants. A number of 2,6-dichlorinated benzene derivatives with various types of substituents in primary position were tested for OM toxicity in mice. In addition, some other 2,6- and 2,5-substituted benzene derivatives were examined. Two novel OM toxicants, 2,6-dichlorobenzaldehyde oxime and 2,6-dichloronitrobenzene, were identified. By the use of partial least squares projection to latent structures with discriminant analysis (PLS-DA) a preliminary quantitative structure-activity relationship (QSAR) model was built also using reported OM toxicity data. Physicochemical properties positively correlated with olfactory mucosal toxicity were identified as molecular dipolar momentum and the electronic properties of the substituent. Inversely correlated descriptors were variables describing the hydrophobicity, electronic properties of the molecule such as electron affinity and the electronic charge on the primary carbon. In conclusion, this preliminary PLS-DA model shows that a 2,6-dichlorinated benzene derivative with a large, polar, and strong electron-withdrawing substituent in the primary position has the potential of being a potent OM toxicant in mice.
|
|
| 10. |
|
|
