1,164 research outputs found
Genotoxicity of DrinkingWater Disinfectants in Plant Bioassays
The genotoxicity of two widely used drinking
water disinfectants, sodium hypochlorite (NaClO)
and chlorine dioxide (ClO2), and a new disinfectant,
peracetic acid (PAA, CH3-CO-COOH), was
evaluated in three short-term plant tests: (1) induction
of anaphase chromosome aberrations in the
root cells of Allium cepa, (2) micronucleus induction
in the root cells of Vicia faba, and (3) micronucleus
induction in Tradescantia pollen cells. The
study was carried out in the laboratory by directly
exposing the plants to several concentrations of
the disinfectants in redistilled water at unadjusted
(acid) and adjusted (neutral) pHs. Both 0.1 and
0.2 mg/l NaClO induced chromosome aberrations
in the Allium cepa test at acid pH, but concentrations
up to 0.5 mg/l of all the disinfectants
were negative at neutral pH. Concentrations ranging
from 0.1 to 0.5 mg/l NaClO, ClO2, and PAA
induced micronuclei in Vicia faba at acid pH,
while 1–2 mg/l NaClO and ClO2 and 0.5–2
mg/l PAA gave positive responses at neutral pH.
Most of concentrations of ClO2 produced positive
responses in the Tradescantia micronucleus test. In
general, the highest levels of genotoxicity were
observed under acid conditions; at acid pH,
significant effects were induced by low concentrations
of ClO2 and PAA. Since the test concentrations
of disinfectants are typical of those
encountered in the biocidal treatment of tap
water and similar concentrations are consumed
daily by a large number of people, the genotoxicity
of these compounds may constitute a significant
public health concern
Sliding mode control of spatial mechanical systems decoupling translation and rotation
This paper looks at the robust trajectory control of spatial mechanical systems using sliding mode techniques. Two distinctions of the proposed method from reported methods are: (1) The measure of attitudinal error used is intrinsically defined, Euclidean-geometric, and intuitive. From Euler's theorem it follows that given a desired and actual attitude of a rigid body there exists an axis and angle of rotation relating the two attitudes. This defines a relative rotation vector, which is used as an intrinsically defined, intuitive measure of error. Reported methods use algebraic differences of entities such as generalized coordinates representing attitude. While functionally correlated to attitudinal error, these measures are not intrinsically defined. (2) A novel, dynamically nonlinear sliding function is used that results in a simple control law. The parameters of this function are dynamically and geometrically intuitive. Simulation results are given for a spacecraft tracking a complex desired trajectory
Influence of Temperature on Mutagenicity in Plants Exposed to Surface Disinfected Drinking Water.
Disinfection of surface drinking water, particularly water chlorination, produces by-products with potential genotoxic and/or carcinogenic activity. A study carried out at a pilot plant for drinking water disinfection of lake water revealed mutagenic activity of three different disinfectants (sodium hypochlorite, chlorine dioxide and peracetic acid) in different seasons using in situ mutagenicity assays, both in animal (micronucleus test) and in plant organisms (anaphase chro- mosomal aberration and micronucleus tests). The effects of the disinfectants appeared to be modulated by the season of exposure. In this study, we tried to understand if (and to what extent) the temperature parameter could actually play an independent role in the registered seasonal variation of mutagenic effects, neglecting the variation of other parameters, e.g. physical conditions and chemical composition of the lake water. Therefore plants (Allium cepa for chromosomal aberration test and Vicia faba for micronucleus test) were exposed to the same disinfected lake-water samples at differ- ent temperatures (10°C, 20°C and 30°C), according the ones registered during the in situ experiment. Long-term expo- sure at the temperatures of 20°C (both Vicia faba and Allium cepa) and 30°C (Vicia faba only) to disinfected waters in- duced clear mutagenic effects. These results show that temperature is an important variable which should be taken into account when in situ exposure of plants is planned for mutagenicity testing. Also, different plant systems clearly show specific temperature ranges suitable for their growth, thereby indicating the need for an accurate selection of the test organism for a specific experimental plan
Prospective randomized comparison of laparoscopic versus open adrenalectomy for sporadic pheochromocytoma.
BACKGROUND: Laparoscopic adrenalectomy for pheochromocytoma remains subject of
debate, owing to the systemic consequences of pneumoperitoneum in patients with
catecholamine-secreting tumors.
METHODS: A prospective randomized study was conducted (2000-2006), evaluating
cardiovascular instability during open (n = 9, group A) or laparoscopic (n = 13,
group B) adrenalectomy for pheochromocytoma. Haemodynamic parameters were
recorded by invasive monitoring.
RESULTS: Haemodynamic instability was observed in 3/9 (group A) and 6/13 patients
(group B), with a mean of 1.8 and 2.2 hypertensive peaks per patient (p = n.s.).
Blood loss (164 +/- 94 cc versus 48 +/- 36 cc, p < 0.05) and operative time (180
+/- 40 versus 158 +/- 45 min, p = n.s.) favored laparoscopic procedures.
Postoperative morbidity and mortality were nil. Hospital stay was shorter in
group B (p < 0.05). Long-term follow-up was always normal.
CONCLUSIONS: Laparoscopic approach for pheochromocytoma can be as safe as open
surgery; intraoperative haemodynamic instability, although usually controlled
with success, remains a source of concern
A stochastic method for the energy management in hybrid electric vehicles
There are many approaches addressing the problem of optimal energy management in hybrid electric vehicles; however, most of them optimise the control strategy for particular driving cycles. This paper takes into account that the driving cycle is not a priori known to obtain a near-optimal solution. The proposed method is based on analysing the power demands in a given receding horizon to estimate future driving conditions and minimise the fuel consumption while cancelling the expected battery energy consumption after a defined time horizon. Simulations show that the proposed method allows charge sustainability providing near-optimal results. (C) 2014 Elsevier Ltd. All rights reserved.This research has been partially supported by Ministerio de Ciencia e Innovacion through Project TRA2010-16205 uDiesel and by the Conselleria de Educacio Cultura i Esports de la Generalitat Valenciana through Project GV/2103/044 AECOSPH.Payri González, F.; Guardiola, C.; Plá Moreno, B.; Blanco-Rodriguez, D. (2014). A stochastic method for the energy management in hybrid electric vehicles. Control Engineering Practice. 29:257-265. https://doi.org/10.1016/j.conengprac.2014.01.004S2572652
Effects of hypotensive and non-hypotensive doses of manidipine on structure, responses to endothelin-1 and ICAM-1 production in mesenteric small resistance arteries of spontaneously hypertensive rats.
We have evaluated the effects of a new calcium channel blocker, manidipine, given at both high, hypotensive and low, non-hypotensive doses, on vascular morphology, response to endothelin-1 and ICAM-1 production in mesenteric small resistance arteries of spontaneously hypertensive rats (SHR).Ten SHR were treated with manidipine 3 mg/kg per day (high dose) and 10 with manidipine 0.3 mg/kg/per day (low dose). The drug was administered by gavage from the 4th to 12th weeks of age. Eighteen Wistar-Kyoto (WKY) rats and 18 SHR were kept untreated as controls. Rats were killed at 13 weeks. Mesenteric small arteries were dissected and mounted on a micromyograph for determination of indexes of vascular structure (media thickness, wall thickness, media/lumen ratio).Systolic blood pressure was significantly reduced by the high dose of the drug, while no effect was observed with low-dose manidipine. A reduction in the media/lumen ratio was observed only in SHR treated with high-dose manidipine. The response to endothelin-1 in untreated SHR was significantly lower in comparison with WKY; a significant reduction was observed in SHR treated with high-dose manidipine. ICAM-1 vascular concentrations were higher in untreated SHR than in WKY controls. Both high- and low-dose manidipine reduced ICAM-1 concentrations toward normalization.Manidipine at high, hypotensive, but not at low, non-hypotensive doses has been proven to reduce structural alterations in mesenteric small resistance arteries, and to normalize vascular responses to endothelin-1. In addition, manidipine, at both low and high doses, may reduce ICAM-1 vascular production, thus suggesting a possible anti-atherogenic effect
Role of heme oxygenase in modulating endothelial function in mesenteric small resistance arteries of spontaneously hypertensive rats.
It has been proposed that endothelial dysfunction is due to the excessive degradation of nitric oxide (NO) by oxidative stress. The enzyme heme-oxygenase (HO) seems to exert a protective effect on oxidative stress in the vasculature, both in animal models and in humans. The objective of this study is to evaluate the effects of inhibition or activation of HO on endothelial function in mesenteric small resistance arteries of spontaneously hypertensive rats (SHR). Six SHR were treated with cobalt protoporphyrin IX 50 mg/Kg (CoPP), an activator of HO; six SHR with stannous mesoporphyrin 30 mg/Kg (SnMP), an inhibitor of HO, and six SHR with saline. As controls, six Wistar-Kyoto rats (WKY) were treated with CoPP, six WKY with SnMP, and six WKY with saline. Drugs were injected in the peritoneum once a week for 2 weeks. Systolic blood pressure (SBP) was measured (tail cuff method) before and after treatment. Mesenteric small resistance arteries were mounted on a micromyograph. Endothelial function was evaluated as a cumulative concentration-response curve to acetylcholine (ACH), before and after pre-incubation with N(G)-methyl-L-arginine (L-NMMA, inhibitor of NO synthase), and to bradykinin (BK). In SHR treatment with CoPP, improved ACH-and BK-induced vasodilatation (ANOVA p < 0.001) and this improvement was abolished by L-NMMA (ANOVA p < 0.001). SnMP was devoid of effects on endothelial function. In WKY, both activation and inhibition of HO did not substantially affect endothelium-mediated vasodilatation. The stimulation of HO seems to induce an improvement of endothelial dysfunction in SHR by possibly reducing oxidative stress and increasing NO availability
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