Bioaccumulation d'aluminium chez la truite Salmo truffa fario soumise au retombées des pluies acides : étude structurale, ultrastructurale et microanalytique

Des études microanalytiques ont été menées sur des truites Salmo trutta fario, âgées de deux ans, récoltées dans une rivière des Vosges soumise aux retombées des pluies acides et sur des truites témoins récoltées dans une rivière d'Auvergne, non soumise aux pluies acides. La rivière des Vosges est caractérisée par un pH de 5,42 et par une concentration en aluminium de 200 µg/L-1. Notre but étant de déterminer les tissus, cellules et organites cibles de bioaccumulation éventuelle de l'aluminium, nous avons analysé rein, foie, branchie et tractus digestif. Deux méthodes microanalytiques ont été utilisées pour localiser l'aluminium à l'échelle cellulaire et subcellulaire et connaître les éléments avec lesquels il peut être associé; ce sont la spectrométrie de masse par émission ionique secondaire (microscope ionique associé à un système informatisé de traitement d'images) et la spectrométrie des rayons X (microsonde électronique de Castaing associée à un microscope électronique à transmission).La microanalyse des rein, foie, branchie et tractus digestif montre l'existence de deux processus conduisant à la bioaccumulation de l'aluminium. Le premier, classiquement connu pour d'autres métaux, met en évidence une insolubilisation de l'aluminium sous forme de phosphate, dans des organites limités par une membrane : les lysosomes et les granules pigmentaires des mélanocytes. Le second, démontre la formation de volumineux dépots extra-cellulaires, atteignant 100 µm de long et entraînant la destruction du tissu. Aucune bioaccumulation significative d'aluminium n'a été observée chez des truites témoins, récoltées dans le centre de la France, où l'eau à pH 7.9 est dépourvue d'aluminium.The major harm caused by acidic precipitation is shown by a disappearance of fish. Other factors besides acidity such as aluminium levels are significantly harmful and many studies have shown that aluminium ions are toxic to fish. The only sensible course of action is to investigate the basic mechanisms by which each of the metal pollutants enters and attacks living systems. For this, one needs to be a combination of physicist, chemist, biochemist, physiologist and toxicologist. Investigations on metal bioaccumulation require very sensitive analytical instrumentation. Total analytical methods commonly used are inadequate : absorbed and adsorbed elements cannot be distinguished.Therefore, interesting information can be obtained by using physical methods of chemical microanalysis : two available microanalytical techniques are particularly suitable, X-ray spectrometry and secondary ion mass spectrometry.X-ray spectrometry, also called Electron Probe X-ray Microanalysis or Electron Microprobe (EMP) provides a means for studying the local chemical composition and structure of biological specimens. EMP can be used in association with a photon microscope or with a transmission electron microscope allowing the detection of elements at subcellular level.The Secondary Ion Mass Spectrometry (SIMS), also called Ion Microscopy, allows to visualize, analyse and photograph the microscopical distribution of the stable or radioactive isotopes of the elements present in a histological section. The sensitivity of the method is very high, ranging from 0.1 to 1 ppm. In association with SIMS, a processing of secondary ion images is used.Two years-old samples of Salmo trutta fario, from wild populations living in acidified waters of Eastern France (near Cornimont in the Vosges moutains) were studied for aluminium detection at cellular and subcellular levels. The acidified waters were characterized by a low pH (5,42) and high aluminium level reaching 200 µg/L-1. Control trouts living in non acidified waters (pH : 7.9 and aluminium free) of central France (near Clermont-Ferrand) were used for comparison. In order top determine the tissues, cells and organelles of a possible aluminium concentration, the following organs were investigated : kidney, liver, gill and digestive tractus, using both microanalytical techniques described above.In the kidney ion images showed aluminium emission from tubule lysosomes with a ring-shaped localization along the apical border of the epithetial cells; aluminium emissions from the tubule lumen and from the pigment granules of the melanocytes were also observed. Using the electron microprobe, X-ray emission spectra of aluminium associated with phosphorus were obtained from lysosomes and pigment granules. In the liver and in the gills, ion images showed a high aluminium emission from the same organelles and X-ray spectra of aluminium and phosphorus were also obtained. Moreover, in the pyloric caeca, large extracellular deposits of aluminium were detected : they measured about 100 µm in length and were located in places where tissues had been destroyed.The same structural, ultrastructural and microanalytical investigations were performed on the control trouts from which non aluminium detection was obtained.In conclusion, two processes appear to be involved in the aluminium accumulation in the brown trout. The first one corresponds to a well known insolubilisation of aluminium phosphate inside the lysosomes, due to an acidic phosphatase enzymatic activity; aluminium is also trapped inside pigment granules. Both of these mechanisms of storage inside membrane-limited organelles, prevent cells from any interior damage. The second one corresponds to the formation of large extracellular deposits which are likely to provoke injuries leading to the tissue destruction. Such data demonstrating basic mechanisms of aluminium accumulation in a fish, could not have been obtained using total analytical methods

“ROC” Chips Readout

International audienceThe OMEGA group at LAL has designed 3 chips for ILC calorimeters: one analog (SPIROC) and one digital (HARDROC) for the hadronic one and also one for the electromagnetic one (SKIROC). The readout and the management of these different chips will be explained. To minimize the lines between the ASICs and the DAQ, the readout is made thanks to 2 lines which are common for all the chips: Data and TransmitOn. As the chips are daisy chained, each chip is talking to the DAQ one after the other. When one chip has finished its readout, it starts the readout of the chip just after. Moreover, during this readout, only the chip which is talking to the DAQ is powered: this is made thanks to the POD (Power On Digital) module in the ASIC. In the ILC mode, readout sequence is active during inter bunch crossing (like ADC conversion). Another chip designed for PMM2 R&D program (PARISROC) integrates a new selective readout: that's mean only hit channels are sent to the DAQ in a complete autonomous mode

Front-end Electronic for the Calice ECAL Physics Prototype

eConf: C050318 : 0902A 18-channel low-noise front-end chip has been designed and produced to read out the 1cm² silicon PIN diodes of the CALICE WSi physics prototype calorimeter. Each channel includes a multi-gain low noise charge preamplifier followed by a bi-gain shaper and a track and hold device. A single output allows reading out every channel at 5 MHz through a multiplexer. Voltage swing is 2.5V with a 5‰ non-linearity. The measured dynamic range on a fixed gain is larger than 13 bits. The gain of the preamplifier can be tuned from 0.3V/pC to 5V/pC with 4 bits. The shaping is done by two fixed-gain shapers (gain 1 and gain 10). Output measured noise is 3000 e- with a detector capacitance of 100pF and a MIP around 42000 e-. Crosstalk is around 1‰. 1000 chips have been produced to equip the physics prototype. Several version of PCB have been designed, taking into account the thickness constraint. A first version with the front-end chip outside the detector has been produced and has been running since January 2005 at DESY, exhibiting an overall MIP/noise ratio of 9. A new thinner version embedding the chip inside the calorimeter has been prototyped and is ready to go in test beam

FLC−SIPM: Front-End Chip for SIPM Readout for ILC Analog HCAL

eConf: C050318 : LCWS-2005-0916An integrated front-end chip has been developed to readout the Silicon PM for the ILC analog hadronic calorimeter. It is built around a variable gain low-noise preamplifier followed by a variable peaking-time shaper (20-200 ns), track and hold and multiplexed output. This structure allows to produce single photo electron spectrum with well separated peaks for absolute calibration at fast shaping (40ns) as well as physics signals from the scintillating fibbers (up to 2000 photo-electrons) with a slower shaping (150ns) compatible with the W-Si Electromagnetic Calorimeter DAQ. Besides, an input DAC allows to tune the detector gain by varying the operating voltage by up to 5V. The chip accommodates 18 channels and 1000 circuits have been produced in 2004, the design and the measurement results of which will be presented

PARISROC, a Photomultiplier Array Integrated Read Out Chip

PARISROC is a complete read out chip, in AMS SiGe 0.35 !m technology, for photomultipliers array. It allows triggerless acquisition for next generation neutrino experiments and it belongs to an R&D program funded by the French national agency for research (ANR) called PMm2: ?Innovative electronics for photodetectors array used in High Energy Physics and Astroparticles? (ref.ANR-06-BLAN-0186). The ASIC (Application Specific Integrated Circuit) integrates 16 independent and auto triggered channels with variable gain and provides charge and time measurement by a Wilkinson ADC (Analog to Digital Converter) and a 24-bit Counter. The charge measurement should be performed from 1 up to 300 photo- electrons (p.e.) with a good linearity. The time measurement allowed to a coarse time with a 24-bit counter at 10 MHz and a fine time on a 100ns ramp to achieve a resolution of 1 ns. The ASIC sends out only the relevant data through network cables to the central data storage. This paper describes the front-end electronics ASIC called PARISROC.Comment: IEEE Nuclear Science Symposium an Medical Imaging Conference (2009 NSS/MIC

HARDROC, Readout chip of the Digital Hadronic Calorimeter of ILC

HARDROC (HAdronic Rpc Detector ReadOut Chip) [1] is the very front end chip designed for the readout of the RPC or Micromegas foreseen for the Digital HAdronic CALorimeter (DHCAL) of the future International Linear Collider. The very fine granularity of the ILC hadronic calorimeters (1cm2 pads) implies a huge number of electronics channels (4 105 /m3) which is a new feature of “imaging” calorimetry. Moreover, for compactness, the chips must be embedded inside the detector making crucial the reduction of the power consumption to 10 μW per channel. This is achieved using power pulsing, made possible by the ILC bunch pattern (1 ms of data acquisition for 199 ms of dead time). HARDROC readout is a semi-digital readout with three thresholds which allows both good tracking and coarse energy measurement, and also integrates on chip data storage. The overall performance of HARDROC will be described with detailed measurements of all the characteristics. Hundreds of chips have indeed been produced and tested before being mounted on printed boards developed for the readout of large scale (1m2) RPC and Micromegas prototypes. These prototypes have been tested with cosmics and also in testbeam at CERN in 2008 and 2009 to evaluate the performance of different kinds of GRPCs and to validate the semi-digital electronics readout system in beam conditions

Digital part of SiPM Integrated Read-Out Chip ASIC for ILC hadronic calorimeter

SPIROC is the Silicium Photo-multiplier (SiPM) Integrated Read-Out Chip designed for the future ILC hadronic calorimeter. It reads 36 SiPMs and has an autotrigger on its 36 channels. Its main requirements are a 100% trigger rate for signal over 1/2 photoelectron, a charge measurement up to 2000 photoelectrons and a time measurement with an accuracy better than 1ns. In order to perform all these functions, SPIROC integrates a complex digital part to manage all the different steps of normal working (acquisition, measure and read-out). This ASIC was submitted in June 2007 (technology AMS SiGe 0.35μm). In this paper, section I describes the general architecture of the ASIC and the main interactions between analogue and digital parts. Section II is dedicated to the different module of the digital part that manages the ASIC

OMEGAPIX: 3D integrated circuit prototype dedicated to the ATLAS upgrade Super LHC pixel project

In late 2008, an international consortium for development of vertically integrated (3D) readout electronics was created to explore features available from this technology. In this paper, the OMEGAPIX circuit is presented. It is the first front-end ASIC prototype designed at LAL in 3D technology. It has been submitted on May 2009. At first, a short reminder of 3D technology is presented. Then the IC design is explained: analogue tier, digital tier and testability

SPIROC (SiPM Integrated Read-Out Chip): Dedicated very front-end electronics for an ILC prototype hadronic calorimeter with SiPM read-out.

Omega et Calice collaborationsInternational audienceThe SPIROC chip is a dedicated very front-end electronics for an ILC prototype hadronic calorimeter with Silicon photomultiplier (or MPPC) readout. This ASIC is due to equip a 10,000-channel demonstrator in 2009. SPIROC is an evolution of FLC_SiPM used for the ILC AHCAL physics prototype [1]. SPIROC was submitted in June 2007 and will be tested in September 2007. It embeds cutting edge features that fulfil ILC final detector requirements. It has been realized in 0.35m SiGe technology. It has been developed to match the requirements of large dynamic range, low noise, low consumption, high precision and large number of readout channels needed. SPIROC is an auto-triggered, bi-gain, 36-channel ASIC which allows to measure on each channel the charge from one photoelectron to 2000 and the time with a 100ps accurate TDC. An analogue memory array with a depth of 16 for each channel is used to store the time information and the charge measurement. A 12-bit Wilkinson ADC has been embedded to digitize the analogue memory content (time and charge on 2 gains). The data are then stored in a 4kbytes RAM. A very complex digital part has been integrated to manage all theses features and to transfer the data to the DAQ which is described on [2]. After an exhaustive description, the extensive measurement results of that new front-end chip will be presented

Performance of a low noise readout ASIC for the W-Si calorimeter physics prototype for the future linear collider

An ASIC (FLC_PHY3) has been developed to readout the test-beam prototype of the future linear collider Tungsten-Silicium calorimeter. It consists of 18 channels low noise charge amplifiers, bi-gain $CRRC^2$ 180 ns shapers, 12bit track and hold and 5 MHz output multiplexer. It covers a dynamic range of 15 bits with a noise of 3500 e- with the 70 pF detector and a linearity at the per-mil level. The preamplifier gain can be adjusted from 0.3 V/pC to 5 V/pC to accomodate various future detectors. The chip dissipates 7 mW/channel and 1000 chips have been produced in AMS 0.8 \mum BiCMOS technology