Hydroxyapatite biomaterial implanted in human periodontal defects: an histological and ultrastructural study

The purpose of the present work was to study the response of human periodontium to hydroxyapatite biomaterial particles (180-200 µm). The biomaterial was implanted in two infraosseous periodontal defects (two patients) after clearing of the granulation tissue. At two months post-surgery, biopsies were studied using light and electron microscopy. No sign of inflammation was observed, the biomaterial aggregates were surrounded either by typical fibroblasts or larger phagocytotic cells with phagocytosis vesicles containing biomaterial crystals. These intracellular crystals were noticeably smaller than the nonphagocytized ones. Some of the phagocytized crystals showed morphological signs of intracellular dissolution. The spaces between the crystals constitutive of the aggregates were filled with organic substance containing collagen fibers.Le présent travail a pour but d’étudier la réponse du parodonte humain à des particules d’hydroxyapatite de 180 à 200 µm. Le biomatériau a été implanté dans deux poches parodontales infraosseuses (deux patients) après élimination du tissu de granulation. Deux mois après l’intervention, des biopsies ont été étudiées en microscopie photonique et en microscopie électronique. Aucun signe d’inflammation n’a été décelé, les agrégats de biomatériau sont bordés soit de fibroblastes, soit de cellules phagocytaires, de taille plus importante, avec des vésicules de phagocytose renfermant des cristaux de biomatériau. Ces cristaux intracellulaires sont notablement plus petits que les cristaux non phagocytés. La morphologie de certains cristaux phagocytés traduit l’existence d’une dissolution intracellulaire. Les espaces entre les cristaux constitutifs des agrégats sont comblés par une substance organique contenant des fibres de collagène

Design, Construction, Operation and Performance of a Hadron Blind Detector for the PHENIX Experiment

A Hadron Blind Detector (HBD) has been developed, constructed and successfully operated within the PHENIX detector at RHIC. The HBD is a Cherenkov detector operated with pure CF4. It has a 50 cm long radiator directly coupled in a window- less configuration to a readout element consisting of a triple GEM stack, with a CsI photocathode evaporated on the top surface of the top GEM and pad readout at the bottom of the stack. This paper gives a comprehensive account of the construction, operation and in-beam performance of the detector.Comment: 51 pages, 39 Figures, submitted to Nuclear Instruments and Method

A Prototype RICH detector using multianode photo multiplier tubes and hybrid photodiodes

The performance of a prototype Ring Imaging Cherenkov Detector is studied using a charged particle beam. The detector performance, using CF4 and air as radiators, is described. Cherenkov angle precision and photoelectron yield using hybrid photo-diodes and multi-anode PMTs agree with simulations and are assessed in terms of the requirements of the LHCb experiment

Performance of a cluster of multi-anode photomultipliers equipped with lenses for use in a prototype RICH detector

A cluster of multi-anode photomultiplier tubes (MaPMTs) equipped with focusing lenses in front of the tubes was tested in a prototype ring imaging Cherenkov (RICH) detector in a charged particle beam. The readout electronics were capable of capturing the data at 40 MHz. The effects due to charged particles and magnetic field on the MaPMT performance were also studied. The results are used to evaluate the MaPMT as a possible photodetector for the LHCb RICH detectors