9,951 research outputs found
Photosynthetic performance and water use efficiency of the fern Cheilanthes persica
No full textMorphological, anatomical and physiological frond traits of Cheilanthes persica (Bory) Mett. ex Kuhn were studied to analyze its adaptive strategy. Mean frond life span is about 340 d. Mature fronds are characterized by 91 g m(-2) areal dry mass (ADM) and 217 g m(-2) succulence. The reduction of frond water content in July (dehydration phase) caused a 51 % decrease in frond surface area (SA). Fronds were dry in August (desiccation phase); nevertheless, in September they showed an increased SA (rehydration phase). Chlorophyll (Chl) a/b ratio, above 3, and the well developed palisade parenchyma (two layers, total thickness of 103.9 mu m) are typical for sun leaves. Chi and carotenoid contents and net photosynthetic rate (P-N) increased during frond development until the highest values in April-May (maturity phase). When mean air temperature reached 31.3 degrees C, stomatal conductance (g(s)) decreased by 34 % and P-N by 33 %. The high pigment contents can dissipate the excess of radiant energy, particularly under unfavourable conditions, when P-N is low. Rather high P-N was found during the rehydration stage. The pronounced decline of mesophyll activity during the declining phase was confirmed by the lowest P-N
Relationship between leaf life-span and photosynthetic activity of Quercus ilex in polluted urban areas (Rome)
No full textAnatomical, morphological and physiological leaf traits of Quercus ilex in response to different traffic levels (high traffic level, type A sites; average traffic level, type B sites; control sites, type C sites) were analysed in Rome. Superficial leaf deposits were analysed comparing unwashed and washed leaf samples. Washing lowered Pb 61% in A, 54% in B and 27% in C. Sr, Fe, Cu, Zn and Al showed the same trend as Pb. The higher photosynthetic activity of 1-year-old leaves (Pn = 7.0 +/- 2.9 mu mol m(-2) s(-1), average value) in A sites with respect to B sites (6.7 +/- 2.4 mu mol m(-2) s(-1)) and C sites (6.7 +/- 1.8 mu mol m(-2) s(-1)) seems to be related to higher stomatal conductance (g(s) = 0.13 +/- 0.06 mol m(-2) s(-1)), higher total chlorophyll content (Chl = 1.57 mg g(-1)) and higher leaf thickness (L-T = 218.9 mu m), particularly palisade parenchyma thickness (109.4 mu m) Q. ilex showed, on average, 95% of 1-year-old leaves and rarely 2-year-old leaves in A and B sites; 77% 1-year leaves, 20% previous-year leaves and sporadic 3-year leaves in C sites. The enhanced leaf senescence in A sites is compensated by a stimulated shoot production (18% higher with respect to C sites); 25% increased specific leaf area seems to be compensatory growth occurring in order to increase the size of the assimilatory area. The inverse trend of leaf life-span and Pn seems to be Q. ilex' adaptive strategy in polluted areas. (C) 2000 Elsevier Science Ltd. All rights reserved
Analisi strutturale delle formazioni forestali presenti nel territorio dei Comuni di Anzio e Nettuno (Roma).
No full textBoosting energy transfer between quantum devices through spectrum engineering in the dissipative ultrastrong coupling regime
No full textThe coherent energy transfer between two quantum devices (a quantum charger
and a quantum battery) mediated by a photonic cavity is investigated, in
presence of dissipative environments, with particular focus on the the
ultrastrong coupling regime. Here, very short transfer times and high charging
power can be achieved in comparison with the usually addressed weak coupling
case. Such phenomenology is further magnified by the presence of level
crossings appearing in the energy spectrum and which reveal very robust against
dissipative environmental effects. Moreover, by carefully control the physical
parameters of the model, e.g. the matter-radiation coupling and the frequencies
of the system, it is possible to tune these crossings making this device more
flexible and experimentally feasible. Finally to broaden our analysis, we
assume the possibility of choosing between a Fock and a coherent initial state
of the cavity, with the latter showing better energetic performances.Comment: 13 pages, 11 figure
Enhancing coherent energy transfer between quantum devices via a mediator
No full textWe investigate the coherent energy transfer between two quantum systems
mediated by a quantum bus. In particular, we consider the energy transfer
process between two qubits, and how it can be influenced by using a third qubit
or photons in a resonant cavity as mediators. Inspecting different figures of
merit and considering both on and off-resonance configurations, we characterize
the energy transfer performances. We show that, while the qubit-mediated
transfer shows no advantages with respect to a direct coupling case, the
cavity-mediated one is progressively more and more efficient as function of the
number of photons stored in the cavity that acts as a quantum bus. The
speeding-up of the energy transfer time, due to a quantum mediator paves the
way for new architecture designs in quantum technologies and energy based
quantum logics.Comment: 19 pages, 11 figure
A cup of hemp coffee by moka pot from southern Italy: An uhplc-hrms investigation
No full textAfter a long period defined by prohibition of hemp production, this crop has been recently re-evaluated in various industrial sectors. Until now, inflorescences have been considered a processing by-product, not useful for the food industry, and their disposal also represents an economic problem for farmers. The objects of the present work are coffee blends enriched with shredded inflorescences of different cultivars of industrial hemp that underwent solid/liquid extraction into the Italian "moka" coffee maker. The obtained coffee drinks were analyzed by Ultra-High-Performance Liquid Chromatography-High Resolution Mass Spectrometry (UHPLC-HRMS) tools for their quali-quantitative phytocannabinoid profiles. The results showed that they are minor constituents compared to chlorogenic acids and caffeine in all samples. In particular, cannabidiolic acid was the most abundant among phytocannabinoids, followed by tetrahydrocannabinolic acid. Neither A ^tetrahydrocannabinol (THC) nor cannabinol, its main oxidation product, were detected. The percentage of total THC never exceeded 0.04%, corresponding to 0.4 mg/kg, far below the current maximum limits imposed by the Italian Ministry of Health. This study opens up a new concrete possibility to exploit hemp processing by-products in order to obtain drinks with high added value and paves the way for further in vitro and in vivo investigations aimed at promoting their benefits for human health
Differences in morphological, physiological and growth traits between two endemic subspecies of Brassica rupestris Raf.: implication for their conservation
No full textThe goal of this work was to analyze the phenological and physiological responses of Brassica rupestris Raf. subsp. hispida Raimondo & Mazzola and Brassica rupestris Raf. subsp. rupestris to environmental factors also in consideration of global change. We used seedlings of the two subspecies originated from wild plants from the natural habitats in Sicily and cultivated in the Botanical Garden of Rome. Leaf morphological and physiological traits and growth dynamic were analyzed as well as the response to an imposed water stress experiment. The results underlined a higher relative growth rate in plant height (RGRH, cm·cm-1·d-1) in B. rupestris subsp. rupestris also attested by the highest plant height (H, cm), leaf area (LA, cm2), specific leaf area (SLA, cm·g-1), total leaf area per plant (TLA, cm2) and total plant dry mass (PDM, g plant-1). Moreover, the significantly highest net photosynthetic rates (A, μmol CO2 m-2·s-1) during the study period of this subspecies was related to the high Chlorophyll content (Chl, SPAD units). B. rupestris subsp. rupestris was also the most tolerant subspecies to imposed water stress showing the highest relative water content (RWC, %), A and water use efficiency (WUE, μmol·mmol-1)
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