169,773 research outputs found
Nanomaterials and nanofabrication for next generation photovoltaics
No full textOn December 2015, almost 200 countries were represented in Paris, discussing on the topics of climate change and Kyoto Protocol. According to the organizing committee at the outset of the talks, the expected key result was an agreement to set a goal of limiting global warming to less than 2°C compared to pre-industrial levels [1]. In order to reach this goal, huge cut on polluted emissions has to be done, finding new resources to produce energy. Photovoltaics is a sustainable and environmentally clean energy source that has the potential to become one of the main ones, in the near future. In order for this to happen, photovoltaics needs to be economically competitive with other conventional energy sources: despite the price of conventional Si solar cells dropped from ~4 USD/WP to ~0.54 USD/WP in the last 15 years [2], the use of new materials to get even more low-cost solar cells created the field of the so-called “new generation photovoltaics”.
Organic (polymeric and small molecules) solar cells have been extensively investigated, in the last years, not only for the potential low fabrication costs, but also for the possibility of building integration and for the solution process realization that allows spray, Roll-toroll and printing techniques, over rigid or flexible substrates. Moreover, perovskite solar cells, that are also compatible with the above mentioned production methods, recently outperformed multicrystalline Si, showing an impressive certified efficiency of 22.1 % [3]. This “new gen” solar cells strictly rely on research performed in the nanometric world: the typical thickness of an active layer for organic solar cell is hundreds of nanometers; phase separation between different components of polymeric solutions are investigated by the mean of Atomic Force Microscopy, which allows to see features in the order of some nanometers; perovskite is likely deposited on top of scaffold with nanometric pores. So, integrate nanomaterials and nanofabrication steps in the realization of such solar cells is of great interest.
In this work, the possible interactions of nanomaterials as Carbon Nanotubes (CNTs) and Nanoporous Alumina, as well as the integration of nanotechnology process such as Nanoimprint Lithography, have been investigated in the field of new gen solar cells. A thorough research on Carbon nanotubes (CNTs) has been carried out to realize semitransparent electrodes to be used as contacts in an organic solar cell. A “two temperature zone” Chemical Vapour Deposition (CVD) set-up is assembled to synthesize CNTs directly on top of Fluorine Doped Tin Oxide and standard glass. The transparency of the asprepared contacts is increased by the mean of a laser patterning technique. An additional technique used to deposit a very thin layer of Nickel, to enhance the conductivity of such semitransparent electrodes, is also presented.
The necessity of decreasing the roughness of the CNTs based electrodes, in order to prevent short circuits in organic solar cells, leads to the development of a spray deposition technique of nanotubes solutions on top of glass substrates. The use of different solutions, with and without the addition of surfactants, as well as the upgrade of the spray set-ups and the design of appropriate metal contacts for inverted organic P3HT:PCBM solar cells are shown.
The inverted architecture of bulk heterojunction solar cell is used also in combination with the Nanoimprint Lithography Technique (NILT): the creation of a pattern of nanometers size on the polymer surface, in order to realize a Photonic Crystal effect designed by optical simulations, is carried out through several technology obstacles, for each of which is given a proper solution.
Lastly, scaffolds of ordered Nanoporous Alumina, realized through the anodization of pure and evaporated Aluminium on glass, are used for the growth of perovskite active layers that are characterized by absorbance measurements
Rapid non-contact detection of chemical warfare agents by laser photoacoustic spectroscopy
No full textNerve agents have recently been used in battlefield operations, espionage wars, and terrorist attacks. These compounds, like some pesticides, cause organophosphate poisoning. The rapid, noncontact detection of a sarin simulant in the liquid phase has been demonstrated at the Diagnostics and Metrology Laboratory of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development using laser photoacoustic spectroscopy, an infrared absorption technology. The first measurements, carried out with an experimental system based on a quantum cascade laser and developed for the assessment of food authenticity in the "fingerprint region", show that a detection limit of one nanolitre is within the reach of the instrument when chemometric analysis is applied
Late atrial potentials and P-wave dispersion identify patients with ischemic heart disease at risk of atrial fibrillation.
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Carbon nanotubes electron source
No full textIn this work we present a carbon nanotubes electron source assembled with a low cost technique. We used a carbon nanotube cathode that reached the remarkable current density of 0,6 A/cm(2). The cathode has been assembled with an external grid in a compact electron source that achieved a maximum output current density of 45 mA/cm(2). This represents one the first examples of a CNTs electron source realized with a low cost assembly
Survey of undesirable behaviors displayed by potential guide dogs with puppy walkers
No full textThis research aimed to identify the frequency and type of undesirable behaviors observed by guide dog puppy walkers and management strategies used by them during the puppy-walking period. All members of 36 puppy-walking families (N = 96), recruited from the National School of Guide Dogs for Blind People in Florence (Italy), completed an 80-item questionnaire. This sampling represented homes caring for 28 Labrador Retrievers, 6 Golden Retrievers, and 2 German shepherd dogs. Of these dogs, 47.2% (n = 17) were males and 52.8% (n = 19) females, and 66.7% (n = 24) were between 7 and 12 months old.Three categories of undesirable behaviors were recorded. First, behaviors considered inconsequential to the guide dog role were: digging (11.8%, n = 11); chewing objects (4.4%, n = 4); stealing or begging for food (3.1%, n = 3); liking people (5.9%, n = 5); getting on furniture (4.4%, n = 4); defending territory (2.8%, n = 2); and coprophagia (5.9%, n = 5). Second, the following behaviors considered easily resolvable through training were recorded: lack of recall (8.9%, n = 10); pulling on lead (11.8%, n = 11); jumping up (28.1%, n = 30); barking at other dogs (5.9%, n = 5); chewing the leash (1.5%, n = 1); and house soiling (5.9%, n = 5). Third, these potentially disqualifying behaviors were observed: scavenging (17.7%, n = 17); aggressive barking, growling, and biting (10.4%, n = 10); and fear of thunderstorms (6.2%, n = 6); loud noises (32.3%, n = 31); men (2.1%, n = 2); women (3.1%, n = 3); and people with unusual clothes (6.2%, n = 6). None of the puppies was reported to be fearful of children.Overall, 66.7% (n = 66) of respondents recorded at least 1 undesirable behavior. However, only few of them might lead to disqualification. The results suggest that most of the puppies were well socialized to people and not fearful.Puppy walkers could contribute to the early assessment of potential behavioral problems, which are a major cause of disqualifying guide dogs.<br/
Seroprevalence of Q fever, brucellosis and leptospirosis in farmers and agricultural workers in Bari, Southern Italy
No full textTo establish the seroprevalence of antibodies to C. burnetii, Leptospira and Brucella in subjects at risk of exposure, 128 workers exposed to farm animals and 280 healthy blood donors were studied. Antibodies to C. burnetii, Leptospira and Brucella were determined by indirect immunofluorescence assay, by microagglutination test (MAT) and by standard tube agglutination test, respectively. Of subjects exposed to farm animals 73.4 % were positive for anti C. burnetii IgG (titer > or = 20) compared to 13.6 % of control subjects (p < 0.0001). The seroprevalence was found mainly among the veterinarians (100 %) and the animal breeding workers (84 %). The trend of percentage of positivity to antibodies to C. burnetii is significant only in the group of workers > or = 70 years, when adjusted for sex and occupation. None of the subjects examined had antibodies to Leptospira and Brucella. Further improvements in the occupational hygiene of the work environment is advisabl
Monitoring of dog bites toward people in a urban environment: an example of an integrated approach
No full textP-wave dispersion, amplitude and integral of the last 20 ms: further parameters of atrial activation useful to identify patients al risk of atrial fibrillation?
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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