We studied the individual and joint acute toxicity of S-metolachlor (SMOC) and deethylatrazine (DEA - a metabolite of atrazine) on different non-target freshwater crustaceans. We used animals from ...different ecological groups: two amphipods from surface running water (Gammarus pulex and Gammarus cf. orinos), an isopod from surface stagnant water (Asellus aquaticus) and an amphipod living in groundwater (Niphargus rhenorhodanensis). Organisms were exposed to different levels of SMOC and DEA, alone or in binary mixture. Temperature effect on SMOC toxicity was assessed by exposing G. pulex and N. rhenorhodanensis to SMOC at 11 °C and 15 °C. Studying mortality as the biological endpoint, N. rhenorhodanensis was more resistant than surface water species towards SMOC and DEA. Among surface water species, G. pulex was the most sensitive while Gammarus cf. orinos and A. aquaticus showed similar responses to both compounds. Temperature increase did not change SMOC toxicity but modify the shape and steepness of the dose-response curve. We used a Model Deviation Ratio (MDR) approach to evaluate the predictability of Concentration Addition (CA) and Independent Action (IA) models to mixture toxicity. Results indicated either an additive or an antagonistic or a synergistic interaction depending on the concentrations combination and the test species. Our finding conclusively show the suitability of CA and IA in predicting mixture toxicities but results should be interpreted with caution according to ecological group of exposed species in risk assessment procedures.
•S-metolachlor (SMOC) and deethylatrazine (DEA) toxicities on non-target crustaceans.•SMOC and DEA are more toxic to surface water species than groundwater one.•Temperature rise did not affect SMOC toxicity but increased its potency.•Joint action predictability by Concentration Addition - Independent Action models.•Significance of species ecological group in risk assessment procedures.
With global climate changes, biological invasions are considered to be one of the main causes of the decline of freshwater biodiversity. In this context, predicted increases in global temperature may ...alter the geographical distributions of native and invasive species. The purpose of our study was to examine the metabolic, behavioral and physiological responses to short-term temperature acclimation of two widely distributed species (the most successful European invader,
Dikerogammarus villosus, and its main victim,
Gammarus pulex), in order to estimate the potential effect of global warming on its invasion of freshwater ecosystems. Our results show that
D. villosus is more vulnerable to high temperatures than
G. pulex. The native species seems to be best adapted to intermediate temperatures (10–20
°C) with a possibility of adjustment to “extreme” temperatures (5–27
°C), whereas the “killer shrimp”
D. villosus seems best adapted to lower temperatures (5–10
°C) with a limited possibility of adjustment above 20
°C. In the light of our results, global warming is likely to be less favorable to the invasive species. However,
D. villosus showed reduced metabolic and activity rates, associated with higher glycogen content. This adaptive strategy was interpreted as having functional advantages, allowing
D. villosus to successfully invade harsh and/or unpredictable biotopes. In addition, our results show that glycogen stores may be used as a powerful indicator of the optimal thermal window for aquatic ectotherms.
As nuclear and particle physics facilities move to higher intensities, the detectors used there must be more radiation tolerant. Diamond is in use at many facilities due to its inherent radiation ...tolerance and ease of use. In this article we present our radiation tolerance measurements of the highest quality polycrystalline Chemical Vapor Deposition (pCVD) diamond material for irradiations from a range of proton energies, pions and neutrons up to a fluence of 2×1016particles/cm2. We have measured the damage constant as a function of energy and particle species and compared it with theoretical models. We also present measurements of the rate dependence of pulse height for non-irradiated and irradiated pCVD diamond pad and pixel detectors, including detectors tested over a range of particle fluxes up to 20 MHz/cm2 with both pad and pixel readout electronics. Our test beam results indicate a 2% upper limit to the pulse height dependence of unirradiated and neutron irradiated pCVD diamond detectors leading to the conclusion that the pulse height in pCVD diamond detectors is, at most, minimally dependent on the particle flux.
We have measured the radiation tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after ...irradiation in a 50 m pitch strip detector fabricated on each diamond sample. We irradiated one group of sensors with 800 MeV protons, and a second group of sensors with 24 GeV protons, in steps, to protons cm−2 and protons cm−2 respectively. We observe the sum of mean drift paths for electrons and holes for both poly-crystalline CVD diamond and single-crystalline CVD diamond decreases with irradiation fluence from its initial value according to a simple damage curve characterized by a damage constant for each irradiation energy and the irradiation fluence. We find for each irradiation energy the damage constant, for poly-crystalline CVD diamond to be the same within statistical errors as the damage constant for single-crystalline CVD diamond. We find the damage constant for diamond irradiated with 24 GeV protons to be and the damage constant for diamond irradiated with 800 MeV protons to be . Moreover, we observe the pulse height decreases with fluence for poly-crystalline CVD material and within statistical errors does not change with fluence for single-crystalline CVD material for both 24 GeV proton irradiation and 800 MeV proton irradiation. Finally, we have measured the uniformity of each sample as a function of fluence and observed that for poly-crystalline CVD diamond the samples become more uniform with fluence while for single-crystalline CVD diamond the uniformity does not change with fluence.
Diamond detector technology, status and perspectives Alexopoulos, A.; Artuso, M.; Bachmair, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
924, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Detectors based on Chemical Vapor Deposition (CVD) diamond have been used extensively and successfully in beam conditions/beam loss monitors as the innermost detectors in the highest radiation areas ...of Large Hadron Collider (LHC) experiments. The startup of the LHC in 2015 brought a new milestone where the first polycrystalline CVD (pCVD) diamond pixel modules were installed in an LHC experiment and successfully began operation. The RD42 collaboration at CERN is leading the effort to develop polycrystalline CVD diamond as a material for tracking detectors operating in extreme radiation environments. The status of the RD42 project with emphasis on recent beam test results is presented.
•Successful operation of the first pCVD diamond planar pixel detector in the ATLAS experiment at the LHC.•Demonstration that the average signal pulse height of pCVD diamond detectors irradiated up to 5×014n∕cm2 is independent of the particle flux up to ∼20 MHz/cm2.•Successful fabrication and operation of the first pCVD diamond 3D pixel detector with 50 micron × 50 micron cells read out with CMS pixel electronics with 3 cell × 2 cell ganging into pixels to match the electronics.•Demonstration that in the pCVD diamond 3D pixel device the efficiency for a MIP was 99% when operating with a 1500 e threshold.
Chemical Vapour Deposition (CVD) diamond is being considered as a material for particle detectors in a harsh radiation environment. This article presents beam test results of 3D pixel detectors ...fabricated with poly-crystalline CVD diamonds. The cells of the devices had a size of 50µm×50µm with columns 2.6µm in diameter. The cells were ganged in a 3×2 and 5×1 pattern to match the layouts of the pixel read-out electronics currently used in the CMS and ATLAS experiments at the Large Hadron Collider, respectively. In beam tests, using tracks reconstructed with a high precision tracking telescope, a tracking efficiency of 99.3% was achieved. The efficiency of both devices plateaus at a bias voltage of 30V. Also irradiated poly-crystalline CVD diamond pad detectors were investigated. In high rate beam tests with particle fluxes up to 20MHz/cm2 and irradiations up to 8 ⋅ 1015n/cm2 it was shown that the pulse height of irradiated poly-crystalline CVD diamonds does not depend on flux to the O2%.
Radiation tolerance of diamond detectors Bäni, L; Artuso, M; Bachmair, F ...
Journal of physics. Conference series,
11/2022, Letnik:
2374, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Diamond is used as detector material in high energy physics experiments due to its inherent radiation tolerance. The RD42 collaboration has measured the radiation tolerance of chemical vapour ...deposition (CVD) diamond against proton, pion, and neutron irradiation. Results of this study are summarized in this article. The radiation tolerance of diamond detectors can be further enhanced by using a 3D electrode geometry. We present preliminary results of a poly-crystalline CVD (pCVD) diamond detector with a 3D electrode geometry after irradiation and compare to planar devices of roughly the same thickness.
Results on radiation tolerance of diamond detectors Venturi, N.; Alexopoulos, A.; Artuso, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
924, Številka:
C
Journal Article
Recenzirano
Odprti dostop
In sight of the luminosity increase of the High Luminosity-LHC (HL-LHC), most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades for their innermost layers in the next 5–10 ...years. These upgrades will require more radiation tolerant technologies than exist today. Usage of Chemical Vapor Deposition (CVD) diamond as detector material is one of the potentially interesting technologies for the upgrade. CVD diamond has been used extensively in the beam condition monitors of BaBar, Belle, CDF and all LHC experiments. Measurements of the radiation tolerance of the highest quality polycrystalline CVD material for a range of proton energies, pions and neutrons obtained with this material are presented. In addition, new results on the evolution of various semiconductor parameters as a function of the dose rate are described.
The existence of resilience mechanisms related to a disturbance, such as invertebrate migrations into the hyporheic zone (HZ, saturated subsurface interstices), promotes persistence of benthic ...communities in river ecosystems. Water exchanges through the HZ, which influence the distribution of biota, are heterogeneous at different scales, determining nested hyporheic flowpaths. The effect of these nested exchanges on the use of the hyporheic refuges by benthic invertebrates is still unknown. We simulated streambed drying in a stream section where hydrological exchanges were considered at riffle (upstream or downstream of riffles) and floodplain (downstream end of a floodplain) scales. Physicochemical indicators determined that local hyporheic flowpaths (up‐ and downwelling zones) were nested in a large‐scale downwelling section of the river. In this situation, the effect of 24 h of experimental drying on the distribution of invertebrates was examined at three sediment depths to follow their migrations into the HZ. Whereas invertebrate assemblages did not change in the control channel, abundance of benthic invertebrate increased in the HZ of the impact channel (up to seven‐fold). Changes occurred rapidly (15–24 h) and only upstream of riffle where surface water down‐welled. The migration was taxon‐specific and concerned the most abundant benthic taxa that temporarily colonize the HZ (“temporary hyporheos,” e.g., Leuctra cf. fusca, Baetis sp., Caenis sp., Orthocladiinae, Tanypodinae). In the context of climate change, hyporheic refuge use will promote persistence of communities facing the increasing frequency of extreme hydrological events. Improved knowledge about the distribution and function of these refuges is becoming crucial for river managers.
The principal aim of this work was to explore the responses of the groundwater crustacean Niphargus rhenorhodanensis to oxidative stress caused by short- and long-term drastic variations in oxygen ...level. To this end, we investigated thiobarbituric acid reactive substances (TBARS) levels and anti-oxidative enzyme (SOD and GPx) activities during 24h anoxia and post-anoxia recovery, and during 10days of severe hypoxia and post-hypoxia recovery. We observed a decrease in TBARS amounts during recovery from severe hypoxia. Parallel to these results, we observed an overactivation of SOD activity after a 24h anoxic stress. GPx activity measured at the end of anoxia or severe hypoxia and in the early hours of post-stress recovery also showed an overactivation compared to the control group. We can hypothesize that this overproduction of GPx corresponded to an anticipatory mechanism coping with the overproduction of reactive oxygen species (ROS) during the recovery phase in subterranean animals. This response could be considered as a major asset for life in alternately normoxic and hypoxic conditions, and therefore in extreme biotopes such as groundwaters.
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