The Experts below are selected from a list of 756 Experts worldwide ranked by ideXlab platform
Nathalie Pradel - One of the best experts on this subject based on the ideXlab platform.
-
Impact of Sterilization methods on dissolved trace metals concentrations in complex natural samples: optimization of UV irradiation
MethodsX, 2019Co-Authors: Sandrine Chifflet, Marianne Quemeneur, Aude Barani, Bernard Angeletti, Morgane Didry, Gérald Grégori, Nathalie PradelAbstract:Sterilization is essential for discriminating biotic responses from abiotic reactions in laboratory experiments investigating biogeochemical processes of complex natural samples. However, the conventional methods used to effectively sterilize materials or culture media do not allow sterilizing complex natural samples while maintaining biogeochemical balances. The aim of this study was to develop a low-cost and easy-to-use method to obtain geochemically unmodified and sterilized samples from complex lacustrine or coastal marine ecosystems. In preliminary assays, the impact of several Sterilization methods (autoclaving, chemical poisoning, microwave, UV irradiation) on the trace metals balances was studied using borosilicate glass (BG), fluorinated ethylene-propylene (FEP) or polyethylene terephthalate (PET) bottles. Unlike other methods, UV Sterilization had minor effects on the distribution of dissolved trace metals. Additional tests using complex lacustrine and coastal marine samples under 10 g/L sediments were performed using a homemade UV Sterilization Chamber designed to simultaneously irradiate a large number samples. Results showed: • very reproducible UV tests in BG and FEP bottles • faster Sterilization using FEP bottles than using BG bottles • low variations of dissolved trace metals concentrations, except for Al, Cu, Fe and Zn
Lh Yahia - One of the best experts on this subject based on the ideXlab platform.
-
using the flowing afterglow of a plasma to inactivate bacillus subtilis spores influence of the operating conditions
Journal of Applied Physics, 2000Co-Authors: S Moreau, M Moisan, Maryam Tabrizian, Jean Barbeau, J Pelletier, A Ricard, Lh YahiaAbstract:The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV emission intensity that sets the Sterilization time as there are always more than sufficient oxygen atoms available for the process.The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV em...
-
using the flowing afterglow of a plasma to inactivate bacillus subtilis spores influence of the operating conditions
Journal of Applied Physics, 2000Co-Authors: S Moreau, A Ricard, M Moisa, Maryam Tabrizia, Jea Arbeau, J Pelletie, Lh YahiaAbstract:The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV em...
Sandrine Chifflet - One of the best experts on this subject based on the ideXlab platform.
-
Impact of Sterilization methods on dissolved trace metals concentrations in complex natural samples: optimization of UV irradiation
MethodsX, 2019Co-Authors: Sandrine Chifflet, Marianne Quemeneur, Aude Barani, Bernard Angeletti, Morgane Didry, Gérald Grégori, Nathalie PradelAbstract:Sterilization is essential for discriminating biotic responses from abiotic reactions in laboratory experiments investigating biogeochemical processes of complex natural samples. However, the conventional methods used to effectively sterilize materials or culture media do not allow sterilizing complex natural samples while maintaining biogeochemical balances. The aim of this study was to develop a low-cost and easy-to-use method to obtain geochemically unmodified and sterilized samples from complex lacustrine or coastal marine ecosystems. In preliminary assays, the impact of several Sterilization methods (autoclaving, chemical poisoning, microwave, UV irradiation) on the trace metals balances was studied using borosilicate glass (BG), fluorinated ethylene-propylene (FEP) or polyethylene terephthalate (PET) bottles. Unlike other methods, UV Sterilization had minor effects on the distribution of dissolved trace metals. Additional tests using complex lacustrine and coastal marine samples under 10 g/L sediments were performed using a homemade UV Sterilization Chamber designed to simultaneously irradiate a large number samples. Results showed: • very reproducible UV tests in BG and FEP bottles • faster Sterilization using FEP bottles than using BG bottles • low variations of dissolved trace metals concentrations, except for Al, Cu, Fe and Zn
S Moreau - One of the best experts on this subject based on the ideXlab platform.
-
using the flowing afterglow of a plasma to inactivate bacillus subtilis spores influence of the operating conditions
Journal of Applied Physics, 2000Co-Authors: S Moreau, M Moisan, Maryam Tabrizian, Jean Barbeau, J Pelletier, A Ricard, Lh YahiaAbstract:The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV emission intensity that sets the Sterilization time as there are always more than sufficient oxygen atoms available for the process.The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV em...
-
using the flowing afterglow of a plasma to inactivate bacillus subtilis spores influence of the operating conditions
Journal of Applied Physics, 2000Co-Authors: S Moreau, A Ricard, M Moisa, Maryam Tabrizia, Jea Arbeau, J Pelletie, Lh YahiaAbstract:The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV em...
A Ricard - One of the best experts on this subject based on the ideXlab platform.
-
characterization of the flowing afterglows of an n2 o2 reduced pressure discharge setting the operating conditions to achieve a dominant late afterglow and correlating the noβ uv intensity variation with the n and o atom densities
Journal of Physics D, 2007Co-Authors: M K Boudam, M Moisan, Bachir Saoudi, A RicardAbstract:The flowing afterglow of an N2–O2 discharge in the 0.6–10 Torr range is examined in the perspective of achieving Sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro–vibrational level of the N2(B) state, indicating a reduced contribution from the early afterglow N2 metastable species. We have studied the influence of operating conditions (pressure, O2 content in the N2–O2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) Chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the Sterilization Chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the Chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow.Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the Chamber entrance: the N atom density goes through a maximum at approximately 0.3–0.5% O2 and then decreases, while the O atom density increases regularly with the O2 percentage. The spatial variation of the N atom (relative) density in the Chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2–5 Torr range, this density is quite uniform everywhere in the Chamber. The (relative) densities of N and O atoms in the discharge are determined by using the actinometry method: the density of N atoms decreases from its maximum value at 0% O2 as the percentage of O2 is increased while the density of O atoms increases, almost linearly, as a function of the percentage of O2, as in the afterglow. The intensity variation of the NOβ UV emission as a function of the percentage of O2 is characterized by a maximum around 0.6% O2 (2 Torr) followed by an approximately exponential decay. We observe that, in the 0–1% O2 range, the UV emission is limited by the availability of O atoms. Beyond this point, the decrease of the UV intensity follows the decrease in the N atom density, while on the average, the O atom density keeps on increasing with O2%. Erosion of polymer microspheres is found to be strongest at the Chamber axis when no O2 is present, implying a dominant early afterglow. Adding even only 1% O2 causes a strong quenching of the N2 metastable species, leading to a dominant late afterglow and therefore considerably reducing the etching rate at the axis. In contrast, at 5 cm from the axis under the same operating conditions, a dominant late afterglow prevails; in the absence of oxygen, erosion is negligible, but it increases regularly as O2 is introduced, following approximately the increase in the O atom density.
-
using the flowing afterglow of a plasma to inactivate bacillus subtilis spores influence of the operating conditions
Journal of Applied Physics, 2000Co-Authors: S Moreau, M Moisan, Maryam Tabrizian, Jean Barbeau, J Pelletier, A Ricard, Lh YahiaAbstract:The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV emission intensity that sets the Sterilization time as there are always more than sufficient oxygen atoms available for the process.The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV em...
-
using the flowing afterglow of a plasma to inactivate bacillus subtilis spores influence of the operating conditions
Journal of Applied Physics, 2000Co-Authors: S Moreau, A Ricard, M Moisa, Maryam Tabrizia, Jea Arbeau, J Pelletie, Lh YahiaAbstract:The flowing afterglow of a microwave discharge can be used to efficiently inactivate bacterial spores. We have conducted a parametric study of the operating conditions of such a system, which shows that the species participating in the killing of spores are oxygen atoms and ultraviolet (UV) photons. The oxygen atoms and the excited atoms and molecules emitting the photons being carried by the flowing afterglow can be made available throughout the Sterilization Chamber. Typical operating conditions are: gas mixture 2%O2/98%N2, pressure range 1–7 Torr and gas flow 0.5–3 slm. Total inactivation of 106 B. subtilis spores is achieved within 40 min with 100 W absorbed microwave power, at afterglow gas temperatures not exceeding 50 °C, a feature of interest for heat sensitive medical devices. The present scheme depends on the gas flow reaching all parts of the objects to be sterilized and on the short-lived active species being transported there sufficiently rapid. Under our operating conditions, it is the UV em...