Chemical control of waterhyacinth (Eichhornia crassipes)

Six assays were carried out under greenhouse conditions to study the efficacy of diquat, glyphosate, sulfosate, imazapyr, 2,4-D, metsulfuron-methyl, sulfentrazone and imazapic in controlling Eichhornia crassipes (Mart.) Solms. The same CO2 pressurized sprayer was used in all assays. Diquat , glyphosate , imazapyr and sulfentrazone were studied in the first assay. Diquat and glyphosate were highly efficient in controlling E. crassipes. The symptoms developed faster in diquat-treated plants. The symptoms promoted by imazapyr and sulfentrazone were progressive all over the experimental period, suggesting that higher control intensity could be achieved obtained during a longer observation time. Waterhyacinth control was studied in the second assay, using diquat, glyphosate, imazapyr, imazapic, 2,4-D, metsulfuron-methyl, and sulphosate. Diquat, glyphosate, imazapyr and 2,4-D showed good control of waterhyacinth The control promoted by diquat and 2,4-D showed quick results. Imazapyr showed slow control action. Under the experimental conditions, imazapic, sulfosate and metsulfuron-methyl did not show good control of this aquatic weed. Waterhyacinth control promoted by imazapyr and glyphosate sprayed at 3, 6, and 9 hours before simulated rain were studied. Glyphosate was more efficient in controlling E. crassipes than imazapyr. For glyphosate, the interval between spraying and rain did not affect the final control (thirty days after spraying), but the development of the symptom was faster at higher doses. In the fourth assay, waterhyacinth control was studied using diquat sprayed during the day or at night. The herbicide was efficient in controlling waterhyacinth at 1,0 L ha-1 or higher. Night spraying showed faster symptoms than day-spraying, but the symptons were similar in the final control. In the fifth assay, diquat's waterhyacinth control efficacy was studied. It was sprayed during the day or night, at intervals of 30, 60 and 120 minutes between spraying and simulated rain. Diquat was very efficient in controlling waterhyacinth, mainly at 2,00 L ha-1. Herbicide action was stronger during night spraying when broader intervals occurred between spraying and the first rain. A last assay was carried out under field conditions, to study waterhyacinth control by imazapyr sprayed on E. crassipes grown in small ponds. All the doses promoted a good waterhyacinth control. The effects were faster at higher doses.Foram testados os produtos 2,4-D, sulfentrazone, glyphosate, diquat, imazapyr, imazapic, metsulfuron-metil e sulfosate. Conduziram-se seis ensaios em condições controladas de casa de vegetação, visando estudar a eficácia no controle de Eichhornia crassipes (Mart.) Solms. Em todos os ensaios, as plantas de aguapé foram cultivadas em caixas com substrato como material de fundo e água completando o volume; os herbicidas foram aplicados com pulverizador costal a CO2. No primeiro ensaio, foram testados os herbicidas diquat, glyphosate, imazapyr e sulfentrazone. O diquat e o glyphosate foram altamente eficazes no controle de E. crassipes, com ação mais rápida do primeiro produto. Imazapyr e sulfentrazone indicaram que maior intensidade de controle poderá ser obtida em maior tempo de observação. No segundo ensaio, foram testados diquat, glyphosate, imazapyr, imazapic, 2,4-D, metsulfuron-metil e sulfosate. Diquat, glyphosate, imazapyr e 2,4-D foram eficazes no controle do aguapé. Diquat e 2,4-D mostraram ação mais rápida. O imazapyr apresentou lenta evolução, e o glyphosate, ação intermediária. Os herbicidas imazapic, sulfosate e metsulfuron, em função do tempo de avaliação, não mostraram eficácia satisfatória. No terceiro ensaio, foram estudados imazapyr e glyphosate aplicados três, seis e nove horas antes da incidência de chuva simulada. O glyphosate apresentou maior eficácia que o imazapyr e o glyphosate não sofreu influência do intervalo entre a aplicação e a ocorrência de chuva. No entanto, o desenvolvimento inicial dos sintomas foi mais rápido em intervalos maiores. No quarto ensaio foi estudado o diquat, aplicado nos períodos noturno e diurno, o qual foi eficiente no controle do aguapé na dose de 1,0 L ha-1 ou acima. Aplicações noturnas apenas proporcionaram ação mais rápida do produto, não influenciando o controle final. No quinto ensaio foi estudado o diquat em aplicações diurnas ou noturnas e em intervalos de 30, 60 e 120 minutos entre a aplicação e a ocorrência de chuva simulada, tendo ele mostrado elevada atividade herbicida contra o aguapé, com eficácia maior na dose de 2,00 L ha-1. A ação do produto foi maior em aplicações noturnas, período em que houve maior importância da extensão do intervalo entre a aplicação do produto e a ocorrência da primeira chuva. O último ensaio foi realizado em campo, para estudo da ação do imazapyr aplicado sobre plantas de aguapé crescidas em caixas de cimento-amianto. Todas as doses estudadas proporcionaram controle total da planta daninha. As doses mais elevadas apresentaram efeitos mais rápidos.899

Simulations of metastable decay in two- and three-dimensional models with microscopic dynamics

We present a brief analysis of the crossover phase diagram for the decay of a metastable phase in a simple dynamic lattice-gas model of a two-phase system. We illustrate the nucleation-theoretical analysis with dynamic Monte Carlo simulations of a kinetic Ising lattice gas on square and cubic lattices. We predict several regimes in which the metastable lifetime has different functional forms, and provide estimates for the crossovers between the different regimes. In the multidroplet regime, the Kolmogorov-Johnson-Mehl-Avrami theory for the time dependence of the order-parameter decay and the two-point density correlation function allows extraction of both the order parameter in the metastable phase and the interfacial velocity from the simulation data.Comment: 14 pages, 4 figures, submitted to J. Non-Crystalline Solids, conference proceeding for IXth International Conference on the Physics of Non-Crystalline Solids, October, 199

Photoluminescence and charge transfer in the prototypical 2D/3D semiconductor heterostructure MoS₂/GaAs

The new generation of two-dimensional (2D) materials has shown a broad range of applications for optical and electronic devices. Understanding the properties of these materials when integrated with the more traditional three-dimensional (3D) semiconductors is an important challenge for the implementation of ultra-thin electronic devices. Recent observations have shown that by combining MoS$_2$ with GaAs it is possible to develop high quality photodetectors and solar cells. Here, we present a study of the effects of intrinsic GaAs, p-doped GaAs, and n-doped GaAs substrates on the photoluminescence of monolayer MoS$_2$. We observe a decrease of an order of magnitude in the emission intensity of MoS$_2$ in all MoS$_2$/GaAs heterojunctions, when compared to a control sample consisting of a MoS$_2$ monolayer isolated from GaAs by a few layers of hexagonal boron nitride. We also see a dependence of the trion to A-exciton emission ratio in the photoluminescence spectra on the type of substrate, a dependence that we relate to the static charge exchange between MoS$_2$ and the substrates when the junction is formed. Scanning Kelvin probe microscopy measurements of the heterojunctions suggest type-I band alignments, so that excitons generated on the MoS$_2$ monolayer will be transferred to the GaAs substrate. Our results shed light on the charge exchange leading to band offsets in 2D/3D heterojunctions which play a central role in the understanding and further improvement of electronic devices.Comment: Accepted in Applied Physics Letter

Effects of starch/polycaprolactone-based blends for spinal cord injury regeneration in neurons/glial cells viability and proliferation

Spinal cord injury (SCI) leads to drastic alterations on the quality of life of afflicted individuals. With the advent of Tissue Engineering and Regenerative Medicine where approaches combining biomaterials, cells and growth factors are used, one can envisage novel strategies that can adequately tackle this problem. The objective of this study was to evaluate a blend of starch with poly(ε-caprolactone) (SPCL) aimed to be used for the development of scaffolds spinal cord injury (SCI) repair. SPCL linear parallel filaments were deposited on polystyrene coverslips and assays were carried out using primary cultures of hippocampal neurons and glial cells. Light and fluorescence microscopy observations revealed that both cell populations were not negatively affected by the SPCL-based biomaterial. MTS and total protein quantification indicated that both cell viability and proliferation rates were similar to controls. Both neurons and astrocytes occasionally contacted the surface of SPCL filaments through their dendrites and cytoplasmatic processes, respectively, while microglial cells were unable to do so. Using single cell [Ca2+ ]i imaging, hippocampal neurons were observed growing within the patterned channels and were functional as assessed by the response to a 30 mM KCl stimulus. The present data demonstrated that SPCL-based blends are potentially suitable for the development of scaffolds in SCI regenerative medicine.Portuguese Foundation for Science and Technology through funds from POCTI and/or FEDER programs (Funding to ICVS, 3B's Research Group and post doctoral fellowship to A.J. Salgado-SFRH/BPD/17595/2004)

Reinforcement of poly-l-lactic acid electrospun membranes with strontium borosilicate bioactive glasses for bone tissue engineering

Herein, for the first time, we combined poly-l-lactic acid (PLLA) with a strontium borosilicate bioactive glass (BBG-Sr) using electrospinning to fabricate a composite bioactive PLLA membrane loaded with 10% (w/w) of BBG-Sr glass particles (PLLA-BBG-Sr). The composites were characterised by scanning electron microscopy (SEM) and microcomputer tomography (μ-CT), and the results showed that we successfully fabricated smooth and uniform fibres (1-3μm in width) with a homogeneous distribution of BBG-Sr microparticles (<45μm). Degradation studies (in phosphate buffered saline) demonstrated that the incorporation of BBG-Sr glass particles into the PLLA membranes increased their degradability and water uptake with a continuous release of cations. The addition of BBG-Sr glass particles enhanced the membrane's mechanical properties (69% higher Young modulus and 36% higher tensile strength). Furthermore, cellular in vitro evaluation using bone marrow-derived mesenchymal stem cells (BM-MSCs) demonstrated that PLLA-BBG-Sr membranes promoted the osteogenic differentiation of the cells as demonstrated by increased alkaline phosphatase activity and up-regulated osteogenic gene expression (Alpl, Sp7 and Bglap) in relation to PLLA alone. These results strongly suggest that the composite PLLA membranes reinforced with the BBG-Sr glass particles have potential as an effective biomaterial capable of promoting bone regeneration. STATEMENT OF SIGNIFICANCE: PLLA membranes were reinforced with 10% (w/w) of strontium-bioactive borosilicate glass microparticles, and their capacity to induce the osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) was evaluated. These membranes presented an increased: degradability, water uptake, Young modulus and tensile strength. We also demonstrated that these membranes are non-cytotoxic and promote the attachment of BM-MSCs. The addition of the glass microparticles into the PLLA membranes promoted the increase of ALP activity (under osteogenic conditions), as well as the BM-MSCs osteogenic differentiation as shown by the upregulation of Alpl, Sp7 and Bglap gene expression. Overall, we demonstrated that the reinforcement of PLLA with glass microparticles results in a biomaterial with the appropriate properties for the regeneration of bone tissue

Demagnetization via Nucleation of the Nonequilibrium Metastable Phase in a Model of Disorder

We study both analytically and numerically metastability and nucleation in a two-dimensional nonequilibrium Ising ferromagnet. Canonical equilibrium is dynamically impeded by a weak random perturbation which models homogeneous disorder of undetermined source. We present a simple theoretical description, in perfect agreement with Monte Carlo simulations, assuming that the decay of the nonequilibrium metastable state is due, as in equilibrium, to the competition between the surface and the bulk. This suggests one to accept a nonequilibrium "free-energy" at a mesoscopic/cluster level, and it ensues a nonequilibrium "surface tension" with some peculiar low-T behavior. We illustrate the occurrence of intriguing nonequilibrium phenomena, including: (i) Noise-enhanced stabilization of nonequilibrium metastable states; (ii) reentrance of the limit of metastability under strong nonequilibrium conditions; and (iii) resonant propagation of domain walls. The cooperative behavior of our system may also be understood in terms of a Langevin equation with additive and multiplicative noises. We also studied metastability in the case of open boundaries as it may correspond to a magnetic nanoparticle. We then observe burst-like relaxation at low T, triggered by the additional surface randomness, with scale-free avalanches which closely resemble the type of relaxation reported for many complex systems. We show that this results from the superposition of many demagnetization events, each with a well- defined scale which is determined by the curvature of the domain wall at which it originates. This is an example of (apparent) scale invariance in a nonequilibrium setting which is not to be associated with any familiar kind of criticality.Comment: 26 pages, 22 figure

Immunosuppressive niche engineering at the onset of human colorectal cancer

The evolutionary dynamics of tumor initiation remain undetermined, and the interplay between neoplastic cells and the immune system is hypothesized to be critical in transformation. Colorectal cancer (CRC) presents a unique opportunity to study the transition to malignancy as pre-cancers (adenomas) and early-stage cancers are frequently resected. Here, we examine tumor-immune eco-evolutionary dynamics from pre-cancer to carcinoma using a computational model, ecological analysis of digital pathology data, and neoantigen prediction in 62 patient samples. Modeling predicted recruitment of immunosuppressive cells would be the most common driver of transformation. As predicted, ecological analysis reveals that progressed adenomas co-localized with immunosuppressive cells and cytokines, while benign adenomas co-localized with a mixed immune response. Carcinomas converge to a common immune “cold” ecology, relaxing selection against immunogenicity and high neoantigen burdens, with little evidence for PD-L1 overexpression driving tumor initiation. These findings suggest re-engineering the immunosuppressive niche may prove an effective immunotherapy in CRC

The Swiss Pathogen Surveillance Platform - towards a nation-wide One Health data exchange platform for bacterial, viral and fungal genomics and associated metadata.

The Swiss Pathogen Surveillance Platform (SPSP) is a shared secure surveillance platform between human and veterinary medicine, to also include environmental and foodborne isolates. It enables rapid and detailed transmission monitoring and outbreak surveillance of pathogens using whole genome sequencing data and associated metadata. It features controlled data access, complex dynamic queries, dedicated dashboards and automated data sharing with international repositories, providing actionable results for public health and the vision to improve societal well-being and health

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio