170 research outputs found
Ammonium to Total Nitrogen Ratio Interactive Effects with Salinity Application on Solanum lycopersicum Growth, Physiology, and Fruit Storage in a Closed Hydroponic System
Soilless Cultivation through an Intensive Crop Production Scheme. Management Strategies, Challenges and Future Directions
Few cycle pulse propagation
We present a comprehensive framework for treating the nonlinear interaction
of few-cycle pulses using an envelope description that goes beyond the
traditional SVEA method. This is applied to a range of simulations that
demonstrate how the effect of a nonlinearity differs between the
many-cycle and few-cycle cases. Our approach, which includes diffraction,
dispersion, multiple fields, and a wide range of nonlinearities, builds upon
the work of Brabec and Krausz[1] and Porras[2]. No approximations are made
until the final stage when a particular problem is considered.
The original version (v1) of this arXiv paper is close to the published
Phys.Rev.A. version, and much smaller in size.Comment: 9 pages, 14 figure
Optically Implemented Broadband Blueshift Switch in the Terahertz Regime
Cataloged from PDF version of article.We experimentally demonstrate, for the first time, an optically implemented blueshift tunable metamaterial in the terahertz (THz) regime. The design implies two potential resonance states, and the photoconductive semiconductor (silicon) settled in the critical region plays the role of intermediary for switching the resonator from mode 1 to mode 2. The observed tuning range of the fabricated device is as high as 26% (from 0.76 THz to 0.96 THz) through optical control to silicon. The realization of broadband blueshift tunable metamaterial offers opportunities for achieving switchable metamaterials with simultaneous redshift and blueshift tunability and cascade tunable devices. Our experimental approach is compatible with semiconductor technologies and can be used for other applications in the THz regime
On negative higher-order Kerr effect and filamentation
As a contribution to the ongoing controversy about the role of higher-order
Kerr effect (HOKE) in laser filamentation, we first provide thorough details
about the protocol that has been employed to infer the HOKE indices from the
experiment. Next, we discuss potential sources of artifact in the experimental
measurements of these terms and show that neither the value of the observed
birefringence, nor its inversion, nor the intensity at which it is observed,
appear to be flawed. Furthermore, we argue that, independently on our values,
the principle of including HOKE is straightforward. Due to the different
temporal and spectral dynamics, the respective efficiency of defocusing by the
plasma and by the HOKE is expected to depend substantially on both incident
wavelength and pulse duration. The discussion should therefore focus on
defining the conditions where each filamentation regime dominates.Comment: 22 pages, 11 figures. Submitted to Laser physics as proceedings of
the Laser Physics 2010 conferenc
Strong and Broadband Pure Optical Activity in 3D Printed THz Chiral Metamaterials
Optical activity (polarization rotation of light) is one of the most desired
features of chiral media, as it is important for many polarization related
applications. However, in the THz region, chiral media with strong optical
activity are not available in nature. Here, we study theoretically, and
experimentally a chiral metamaterial structure composed of pairs of vertical
U-shape resonators of "twisted" arms, and we reveal that it demonstrates large
pure optical activity (i.e. optical activity associated with negligible
transmitted wave ellipticity) in the low THz regime. The experimental data show
polarization rotation up to 25 (deg) for an unmatched bandwidth of 1 THz
(relative bandwidth 80 %), from a 130 um-thickness structure, while theoretical
optimizations show that the rotation can reach 45 (deg). The enhanced chiral
response of the structure is analyzed through an equivalent RLC circuit model,
which provides also simple optimization rules for the enhancement of its chiral
response. The proposed chiral structures allow easy fabrication via direct
laser writing and electroless metal plating, making them suitable candidates
for polarization control applications.Comment: 17 pages, 7 figure
Inhibicija rasta plijesni Aspergillus ochraceus ZMPBF 318 i Penicillum expansum ZMPBF 565 djelovanjem četiriju eteričnih ulja
Fungi produce a large variety of extracellular proteins, organic acids, and other metabolites and can adapt to several environmental conditions. Mycotoxin-producing moulds of the genera Aspergillus and Penicillium are common food contaminants. One of the natural ways to protect food from mould contamination is to use essential oils. In this study, we evaluated the effect of essential oils of cinnamon, lavender, rosemary, and sage at 1 % (v/v) concentration in yeast media inoculated with spores (fi nal concentration 106 mL-1 media) of Aspergillus ochraceus ZMPBF 318 and Penicillium expansum ZMPBF 565, alone or in combination, on fungal biomass. Cinnamon showed the best inhibitory effect (100 %). Lavender oil best inhibited the growth of Aspergillus ochraceus (nearly 100 %), and was less successful with Penicillium expansum (having dropped to 57 % on day 28). With cultivation time the inhibitory effect of sage and rosemary oil grew for Aspergillus ochraceus and dropped for Penicillium expansum. These results suggest that fungi can be controlled with essential oils, especially with cinnamon oil.Plijesni su poznate po svojoj visokoj sposobnosti proizvodnje različitih izvanstaničnih proteina, organskih kiselina i drugih metabolita i po svojoj mogućnosti prilagodbe na nepovoljne okolišne uvjete, a primjenjuju se i u obradi otpadnih voda. Plijesni iz rodova Aspergillus i Penicillium česti su kontaminanti u hrani i posebno opasne jer tvore toksične metabolite mikotoksine. Eterična ulja mogu se primijeniti kao prirodna sredstva za zaštitu hrane od kontaminacije plijesnima. U radu su prikazani rezultati istraživanja utjecaja eteričnih ulja cimeta, lavande, ružmarina i kadulje na kontrolu rasta biomase plijesni Aspergillus ochraceus ZMPBF 318 i Penicillium expansum ZMPBF 565, u obliku čistih i miješanih kultura. Ulja su dodavana u koncentraciji od 1 % (v/v), a podloga (kvaščev ekstrakt) bila je nacijepljena suspenzijama spora plijesni
(106 mL-1 podloge). Eterično ulje cimeta pokazalo je najveći inhibitorni učinak (100 %). Inhibitorni učinak eteričnog ulja lavande bio je veći na rast Aspergillusa ochraceusa (skoro 100 %) nego Penicilliuma expansuma (57 %). Eterična ulja kadulje i ružmarina pokazala su suprotne učinke. Inhibitorni učinak na Aspergillus ochraceus tijekom perioda uzgoja je rastao, a na Penicillium expansum opadao.
Rezultati pokazuju da se rast plijesni može kontrolirati primjenom eteričnih ulja, a posebno uljem cimeta. Također upućuju na ekonomsku vrijednost takvih tretmana
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