Temperature dependence of the coercive field in single-domain particle systems

The magnetic properties of Cu97Co3 and Cu90Co10 granular alloys were measured over a wide temperature range (2 to 300K). The measurements show an unusual temperature dependence of the coercive field. A generalized model is proposed and explains well the experimental behavior over a wide temperature range. The coexistence of blocked and unblocked particles for a given temperature rises difficulties that are solved here by introducing a temperature dependent blocking temperature. An empirical factor gamma arise from the model and is directly related to the particle interactions. The proposed generalized model describes well the experimental results and can be applied to other single-domain particle system.Comment: 7 pages, 8 figures, revised version, accepted to Physical Review B on 29/04/200

Probing dark energy beyond z=2z=2 with CODEX

Precision measurements of nature's fundamental couplings and a first measurement of the cosmological redshift drift are two of the key targets for future high-resolution ultra-stable spectrographs such as CODEX. Being able to do both gives CODEX a unique advantage, allowing it to probe dynamical dark energy models (by measuring the behavior of their equation of state) deep in the matter era and thereby testing classes of models that would otherwise be difficult to distinguish from the standard $\Lambda$CDM paradigm. We illustrate this point with two simple case studies.Comment: 4 pages, 4 figures; submitted to Phys. Rev.

Synthesis of sub-5 nm Co-doped SnO2_2 nanoparticles and their structural, microstructural, optical and photocatalytic properties

A swift chemical route to synthesize Co-doped SnO$_2$ nanopowders is described. Pure and highly stable Sn$_{1-x}$Co$_x$O$_{2-\delta}$ (0 $\le$ x $\le$ 0.15) crystalline nanoparticles were synthesized, with mean grain sizes < 5 nm and the dopant element homogeneously distributed in substitutional sites of the SnO$_2$ matrix. The UV-visible diffuse reflectance spectra of the Sn$_{1-x}$Co$_x$O$_{2-\delta}$ samples reveal red shifts, the optical bandgap energies decreasing with increasing Co concentration. The Urbach energies of the samples were calculated and correlated with their bandgap energies. The photocatalytic activity of the Sn$_{1-x}$Co$_x$O$_{2-\delta}$ samples was investigated for the 4-hydroxylbenzoic acid (4-HBA) degradation process. A complete photodegradation of a 10 ppm 4-HBA solution was achieved using 0.02% (w/w) of Sn$_{0.95}$Co$_{0.05}$O$_{2-\delta}$ nanoparticles in 60 min of irradiation.Comment: 29 pages, 2 tables, 10 figure

Desenvolvimento de Physocleora dimidiaria (Guenée, 1852) (Lepidoptera:Geometridae) em hospedeiros naturais.

Foi estudado o desenvolvimento de Physocleora dimidiaria (Guenée, 1852) em Malus domestica (MD), Trifolium repens (TR) e Rumex obtusifolius (RO) em laboratório. A duração da fase larval foi maior em MD (34,5 ± 0,89 dias) e menor em TR (23,4 ± 0,41 dias) e RO (24,9 ± 0,44 dias). O desenvolvimento de pupa (13 dias), peso de pupas (0,07g), fecundidade (entre 191,9 e 431 ovos), incubação (9 dias), longevidade (11 dias), pré-oviposição (1 dias), oviposição (7 dias) e a taxa líquida de reprodução (entre 59,3 e 183,6 fêmeas) não diferiram. A fertilidade foi menor em TR (20,5 ± 9,01 %) que em RO (71,5 ± 16,30 %). O tempo de uma geração foi superior em MD (60,0 ± 1,16 dias)

Transfer reactions and the dispersive optical-model

The dispersive optical-model is applied to transfer reactions. A systematic study of $(d,p)$ reactions on closed-shell nuclei using the finite-range adiabatic reaction model is performed at several beam energies and results are compared to data as well as to predictions using a standard global optical-potential. Overall, we find that the dispersive optical-model is able to describe the angular distributions as well as or better than the global parameterization. In addition, it also constrains the overlap function. Spectroscopic factors extracted using the dispersive optical-model are generally lower than those using standard parameters, exhibit a reduced dependence on beam energy, and are more in line with results obtained from $(e,e'p)$ measurements.Comment: Phys. Rev. C 84, 044611 (2011

The use of a three-point support flexural test to predict the stiffness of anisotropic composite plates in bending

http://www.sciencedirect.com/science/journal/01429418Anisotropic polymeric matrix composite discs supported on three points were subjected to a non-destructive bending test to study their behaviour in complex flexural loading situations. The results show that the flexural behaviour of the composites depends on several factors, such as fibre orientation, laminate stacking, surface waviness and moulding temperature. The experimental data were compared with those obtained from the finite element program software Algor. Differences up to 13% were found between the experimental and simulated values of the flexural stiffness. In spite of that, it was concluded that the non-destructive test used is a useful tool to predict the behaviour of anisotropic composites and to validate the results obtained from computer FEM analysis

Fungicides performance on the control of asian soybean rust (Phakopsora pachyrhizi) in Goias State, Brazil.

The use of fungicides remains the most important tool to Asian soybean rust (ASR) control in Brazil. The reduction of the Phakopsora pachyrhizi sensibility to triazols changed the strategy to the exclusive use of fungicides to strobilurines with triazols premix formulations. Two field trials of the Brazilian network for ASR chemical control were conducted in Goiania and Senador Canedo at Goias State in order to compare the efficacy of 17 fungicides on ASR control. The treatments were composed by two triazols, one strobilurine, one carboxanilide, and 13 premix formulations of strobilurine + triazol. The fungicides were applied twice, beginning at soybean growth stage R1 in absence of ASR symptoms (preventatively), and 21 days after first spray. The soybean cultivars were BRS 8160 RR in Goiania and BRS Valiosa RR in Senador Canedo. The area under disease progress curve (AUDPC) was calculated for each treatment based on four ASR severity evaluations from R1 to R7 soybean growth stages. The lower AUDPC and higher soybean yield were observed for almost all fungicides in premix formulations of strobilurine with triazols. The carboxanilide oxycarboxin and the triazols tebuconazole and cyproconazole were not so efficient on ASR control. The lowest reductions of soybean cycle due to ASR were observed with picoxystrobin + tebuconazole, which were 12 days later in relation to the untreated plots in Goiania and 10 days later in Senador Canedo