A prototype silicon-tungsten electromagnetic calorimeter for an ILC detector was tested in 2007 at the CERN SPS test beam. Data were collected with electron and hadron beams in the energy range 8 to ...80 GeV. The analysis described here focuses on the interactions of pions in the calorimeter. One of the main objectives of the CALICE program is to validate the Monte Carlo tools available for the design of a full-sized detector. The interactions of pions in the Si-W calorimeter are therefore confronted with the predictions of various physical models implemented in the GEANT4 simulation framework.
An analog hadron calorimeter (AHCAL) prototype of 5.3 nuclear interaction lengths thickness has been constructed by members of the CALICE Collaboration. The AHCAL prototype consists of a 38-layer ...sandwich structure of steel plates and highly-segmented scintillator tiles that are read out by wavelength-shifting fibers coupled to SiPMs. The signal is amplified and shaped with a custom-designed ASIC. A calibration/monitoring system based on LED light was developed to monitor the SiPM gain and to measure the full SiPM response curve in order to correct for non-linearity. Ultimately, the physics goals are the study of hadron shower shapes and testing the concept of particle flow. The technical goal consists of measuring the performance and reliability of 7608 SiPMs. The AHCAL was commissioned in test beams at DESY and CERN. The entire prototype was completed in 2007 and recorded hadron showers, electron showers and muons at different energies and incident angles in test beams at CERN and Fermilab.
The CALICE collaboration is studying the design of high performance electromagnetic and hadronic calorimeters for future International Linear Collider detectors. For the electromagnetic calorimeter, ...the current baseline choice is a high granularity sampling calorimeter with tungsten as absorber and silicon detectors as sensitive material. A ``physics prototype'' has been constructed, consisting of thirty sensitive layers. Each layer has an active area of 18x18 cm2 and a pad size of 1x1 cm2. The absorber thickness totals 24 radiation lengths. It has been exposed in 2006 and 2007 to electron and hadron beams at the DESY and CERN beam test facilities, using a wide range of beam energies and incidence angles. In this paper, the prototype and the data acquisition chain are described and a summary of the data taken in the 2006 beam tests is presented. The methods used to subtract the pedestals and calibrate the detector are detailed. The signal-over-noise ratio has been measured at 7.63 +/- 0.01. Some electronics features have been observed; these lead to coherent noise and crosstalk between pads, and also crosstalk between sensitive and passive areas. The performance achieved in terms of uniformity and stability is presented.
Much research has been done on bone cells, but only a few studies deal with biomaterial-induced effects on human osteoclasts, which may take on an important role in the successful regeneration of ...bone. In order to highlight such effects, human peripheral blood mononuclear cells (PBMCs) were extracted from venous blood, differentiated to osteoclasts and then cultured in, the presence of five particulate hydroxyapatite (HA)/β-tricalcium phosphate (TCP) biomaterials, on bovine bone slices and glass cover slips. The biomaterials, AlgOSS 50/50 (50 % HA/50 % TCP), AlgOSS 20/80 (20 % HA/80 % TCP), Algipore (98 % HA), Cerasorb (100 % TCP) and Bio-Oss (100 % HA) were chosen to assess their influence on cell morphology and numbers. Light microscopic evaluation was performed during ongoing cell culture. After 21 d of cultivation, the biomaterial-induced effects on osteoclastic resorption of the bone slices were evaluated by scanning electron microscopy (SEM). Osteoclast-like cells were identified by TRAP staining. All five biomaterials showed larger area fractions of resorbed bone than the control (5.6 ± 6.8 %), as measured on SEM images. The purely hydroxyapatite-based Algipore (9.8 ± 9.7 %) and Bio-Oss (7.9 ± 8.8 %) showed significantly elevated area fraction rates (p ≤ 0.05) of bone resorption. Light microscope evaluation revealed a significant, but inhibiting effect of Cerasorb (p = 0.05). These data indicated that introducing of small biomaterial hydroxyapatite particles may have improved the performance of bone substitute materials.
Aerosols of biological origin play a vital role in the Earth system, particularly in the interactions between atmosphere, biosphere, climate, and public health. Airborne bacteria, fungal spores, ...pollen, and other bioparticles are essential for the reproduction and spread of organisms across various ecosystems, and they can cause or enhance human, animal, and plant diseases. Moreover, they can serve as nuclei for cloud droplets, ice crystals, and precipitation, thus influencing the hydrological cycle and climate. The sources, abundance, composition, and effects of biological aerosols and the atmospheric microbiome are, however, not yet well characterized and constitute a large gap in the scientific understanding of the interaction and co-evolution of life and climate in the Earth system. This review presents an overview of the state of bioaerosol research, highlights recent advances, and outlines future perspectives in terms of bioaerosol identification, characterization, transport, and transformation processes, as well as their interactions with climate, health, and ecosystems, focusing on the role bioaerosols play in the Earth system.
•Aerosols of biological origin play a vital role in the Earth system.•Bioaerosols are essential for biological reproduction and can cause diseases.•Bioparticles can serve as nuclei for cloud droplets, ice crystals, and precipitation.•Interaction and co-evolution of life and climate in the Earth system•Overview of the state of bioaerosol research and recent advances
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract The present study investigated the suitability of three different absorbable biocomposites for the repair of critical sized bone defects created at the mandibular angle of adult sheep. Each ...biocomposite was composed of a three-dimensional individualized polylactide scaffold, containing a tricalcium phosphate biomaterial (chronOS® ). Either autologous bone marrow (chOS/BoneMarrow) or coagulation factor XIII (chOS/FactorXIII) was added to the biomaterial for osteopromotion. Venous whole blood (chOS/Blood) added to the biomaterial served as a control. A total of 18 adult sheep were used for implantation studies, subdivided into three groups of six animals each. After 12 weeks of observation, the animals were sacrificed and the mandibles were retrieved for qualitative and quantitative histologic assessment within three regions of interest (transitional zone, center, and periphery) throughout the biocomposites. Successful bone regeneration was defined by the absence of scaffold deformation and the presence of new bone formation within the biocomposites. In histomorphometry, only chOS/BoneMarrow showed elevated area fractions of newly formed bone in all regions of interest (transitional zone 50.7 ± 7.5, center 31.9 ± 9.3, periphery 23.1 ± 13.5). This led to preservation of the macroscopic scaffold structure in all specimens. Zero hurdle regression confirmed this by validating the factor biocomposite as significant (p < 0.001) for regeneration success. In our experiment, chOS/BoneMarrow was the only biocomposite passing the hurdle of regeneration in all three regions of interest. In contrast, bone formation was less pronounced and uniform in chOS/FactorXIII and chOS/blood-containing specimens. In these groups, scaffolds showed obvious to significant deformation. Overall, autologous bone marrow showed the most promising results in our experimental setting. As opposed to reports in the literature, we could not confirm the suitability of coagulation factor XIII to promote bone formation, since bone formation rates were comparable only to those of the control venous blood.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In recent years, severe haze events often occurred in China, causing serious environmental problems. The mechanisms responsible for the haze formation, however, are still not well understood, ...hindering the forecast and mitigation of haze pollution. Our study of the 2012-13 winter haze events in Beijing shows that atmospheric water vapour plays a critical role in enhancing the heavy haze events. Under weak solar radiation and stagnant moist meteorological conditions in winter, air pollutants and water vapour accumulate in a shallow planetary boundary layer (PBL). A positive feedback cycle is triggered resulting in the formation of heavy haze: (1) the dispersal of water vapour is constrained by the shallow PBL, leading to an increase in relative humidity (RH); (2) the high RH induces an increase of aerosol particle size by enhanced hygroscopic growth and multiphase reactions to increase particle size and mass, which results in (3) further dimming and decrease of PBL height, and thus further depressing of aerosol and water vapour in a very shallow PBL. This positive feedback constitutes a self-amplification mechanism in which water vapour leads to a trapping and massive increase of particulate matter in the near-surface air to which people are exposed with severe health hazards.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Atmospheric aerosol particles of biological origin are a very diverse group of biological materials and structures, including microorganisms, dispersal units, fragments and excretions of biological ...organisms. In recent years, the impact of biological aerosol particles on atmospheric processes has been studied with increasing intensity, and a wealth of new information and insights has been gained. This review outlines the current knowledge on major categories of primary biological aerosol particles (PBAP): bacteria and archaea, fungal spores and fragments, pollen, viruses, algae and cyanobacteria, biological crusts and lichens and others like plant or animal fragments and detritus. We give an overview of sampling methods and physical, chemical and biological techniques for PBAP analysis (cultivation, microscopy, DNA/RNA analysis, chemical tracers, optical and mass spectrometry, etc.). Moreover, we address and summarise the current understanding and open questions concerning the influence of PBAP on the atmosphere and climate, i.e. their optical properties and their ability to act as ice nuclei (IN) or cloud condensation nuclei (CCN). We suggest that the following research activities should be pursued in future studies of atmospheric biological aerosol particles: (1) develop efficient and reliable analytical techniques for the identification and quantification of PBAP; (2) apply advanced and standardised techniques to determine the abundance and diversity of PBAP and their seasonal variation at regional and global scales (atmospheric biogeography); (3) determine the emission rates, optical properties, IN and CCN activity of PBAP in field measurements and laboratory experiments; (4) use field and laboratory data to constrain numerical models of atmospheric transport, transformation and climate effects of PBAP.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Secondary organic aerosol (SOA) particles are formed in the atmosphere from condensable oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs). On a global scale, biogenic ...VOCs account for about 90% of VOC emissions and of SOA formation (90 billion kilograms of carbon per year). SOA particles can scatter radiation and act as cloud condensation or ice nuclei, and thereby influence the Earth's radiation balance and climate. They consist of a myriad of different compounds with varying physicochemical properties, and little information is available on the phase state of SOA particles. Gas-particle partitioning models usually assume that SOA particles are liquid, but here we present experimental evidence that they can be solid under ambient conditions. We investigated biogenic SOA particles formed from oxidation products of VOCs in plant chamber experiments and in boreal forests within a few hours after atmospheric nucleation events. On the basis of observed particle bouncing in an aerosol impactor and of electron microscopy we conclude that biogenic SOA particles can adopt an amorphous solid-most probably glassy-state. This amorphous solid state should provoke a rethinking of SOA processes because it may influence the partitioning of semi-volatile compounds, reduce the rate of heterogeneous chemical reactions, affect the particles' ability to accommodate water and act as cloud condensation or ice nuclei, and change the atmospheric lifetime of the particles. Thus, the results of this study challenge traditional views of the kinetics and thermodynamics of SOA formation and transformation in the atmosphere and their implications for air quality and climate.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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