Charge-displacement analysis as a tool to study chalcogen bonded adducts and predict their association constants in solution

The secondary interaction between a polarized chalcogen atom and different Lewis bases, either anionic or neutral, has been studied by charge displacement analysis. Using charge displacement analysis, the charge rearrangement in the adduct upon the formation of the interaction has been quantified and described in great detail. By comparing the theoretical results with the experimental association con- stants, two linear correlations can be found for anionic and neutral bases. Such correlations can be used to reliably predict the association constants of adducts for which experimental data are not available yet

DETERMINAÇÃO DA REAÇÃO FOLIAR À EXPOSIÇÃO DE RADIAÇÃO LASER

A mosca branca Bemisia tabaci é uma das mais importantes pragas do feijoeiro, principalmente devido à transmissão de viroses. O controle dessa praga tem sido realizado com uso intensivo de agrotóxicos, o que além de ser potencialmente nocivo ao ambiente, é oneroso e por vezes, ineficaz. Por essa razão, é necessário desenvolver novas ferramentas de controle da mosca branca que contribuam com o manejo racional de agrotóxicos, como por exemplo, o uso de radiação eletromagnética LASER, que pode ser uma opção mais sustentável por não deixar resíduos no ambiente

DESENVOLVIMENTO DO SOFTWARE DE GESTÃO DO TUBO KALILE V3.0 PARA INVESTIGAÇÃO CIENTÍFICA EM INSETOS ALVO

A adaptação de insetos infestantes em plantações é particularmente rápida e, por conta disso, os agricultores, assim como o agronegócio todo, sofrem prejuízos significativos e com tendência a aumentar. As pulverizações, certamente não baratas, devem ser realizadas com uma maior frequência para garantir o controle populacional dos infestantes, diminuindo assim o lucro, a qualidade dos alimentos para a população e afetam negativamente os parâmetros de salubridade ambiental tanto nas áreas cultivadas, quanto naquelas próximas ao cultivo

Efeitos da Radiação Eletromagnética LASER em Diaphorina citri

Os níveis que a humanidade chegou no uso de pesticidas alarma os órgãos internacionais de controle da saúde coletiva, especialmente no Brasil. À toxicidade ambiental que aumenta, não corresponde um avanço no combate às pragas que afetam muitas das atividades produtivas. Por isso é necessário o uso de técnicas ambientalmente corretas e eficientes para garantir a subsistência da população mundial e o acesso a alimentos saudáveis. Neste trabalho é descrita a eficiência do uso do LASER na letalidade da Diaphorina citri pela exposição direta e indireta à radiação, e a perspectiva de limitar sua dispersão entre pomares cítricos ao acoplar o LASER a um sistema de reconhecimento e morte de insetos. Os resultados obtidos nos experimentos sugerem a utilização em outros tipos de pragas

Alternative hyperspherical adiabatic decoupling scheme for tetratomic molecules: quantum two-dimensional study of the ammonia umbrella motion

The prototypical example of the inversion of ammonia is studied as an approach to hyperspheric decoupling schemes for tetratomic molecule. We perform two-dimensional calculations including totally symmetric stretching and inversion modes, associated to the hyperradius and an hyperangle. Two adiabatic procedures are employed: the hyperradial one where the hyperangular part is solved to give hyperradial adiabatic curves, and the hyperangular one where the hyperradial part is solved to give hyperangular adiabatic curves. Two methodologies are employed: the hyperquantization algorithm and the finite element method. For completeness a diabatic procedure is also formulated

Umbrella motion of the methyl cation, radical, and anion molecules

The main purpose of the present work is to characterize the umbrella inversion motion of the CH-3, CH3 and CH-3 molecules as a function of the environmental conditions. In particular, for the three investigated species we have studied how temperature affects times for umbrella inversion modes and their propagation velocity. These data are used to predict the statistical behavior of the reactions involving the AB3 like molecules and to relate the umbrella potential with the rate constants. The second aspect of this study concerns the molecular distribution charges as a function of the umbrella opening angle and of the total charge. The results have been used to calculate the induced electric field on a probe charge located at a given position perpendicular to the plane of the hydrogen atoms which is the most relevant for the reaction. Obtained values are presented as a function of the umbrella opening angle

New Biocompatible Technique Based on the Use of a Laser to Control the Whitefly <i>Bemisia tabaci</i>

The whitefly Bemisia tabaci is among the most important agricultural pests in the world and one of the world’s top 10 most invasive insect pests. Bemisia tabaci is associated with severe yield and quality losses, mainly due to the transmission of plant viruses, as in the case of common beans (Phaseolus vulgaris L.). Reducing insecticide applications is a research priority, e.g., developing innovative and clean tools such as electromagnetic waves. The present work aims to determine the effective parameters of laser to reduce the Bemisia tabaci population in common beans. Preliminary assays were conducted by manually irradiating continuous-wave laser beams with different wavelengths (444 nm, 527 nm, and 640 nm) and optical intensities directly on the insects. Among these, the most effective wavelength was 444 nm. Later, we repeated the experiments using a homemade automated system to control the exposure time (t1 = 1 s, t2 = 2 s, t3 = 3 s and t4 = 4 s) of whiteflies to the incident beam at different optical intensities (I1 ≈ 10 Wcm−2, I2 ≈ 4 Wcm−2, I3 ≈ 2 Wcm−2). We have achieved 100% insect mortality by irradiating 454 nm laser wavelength on the 3rd instar nymphs of Bemisia tabaci, with the following parameters: I1(t1), I2(t3) and I3(t4). Moreover, the laser irradiation test did not affect plant yield and development, revealing that our preliminary results present a photonic technique that could control whiteflies without harming the plants’ development

Umbrella motion of the methyl cation, radical, and anion molecules

A study of the umbrella motion of the methyl cation, radical, and anion molecules is presented. This is the floppiest mode of vibration of all three species and its characterization is of fundamental importance for understanding their reactivity. Minimum Energy Paths of the umbrella motions according to the hyperspherical treatment were obtained, by single point calculations, at the CCSD(T)/aug-cc-pVQT level of theory in the Born-Oppenheimer approximation. These energy profiles permit us to calculate the vibrational levels through the Hyperquantization algorithm, which is shown appropriated for the description of the umbrella motion of these three molecules. The adiabatic electron affinity and ionization potentials were estimated to good accuracy. Partition functions are also calculated in order to obtain information on the reaction rates involving these groups