In vitro cultivation of Brosimum gaudichaudii Tréc. (Moraceae)

O objetivo desta pesquisa foi avaliar o potencial organogenético de entrenós, discos foliares, e raízes de Brosimum gaudichaudii utilizando 12 diferentes combinações dos fitorreguladores 6-benzilaminopurina e ácido naftaleno acético, em meio MS (diluído à metade), sólido (6,5 g de ágar), e com 20 g.L-1 de sacarose. Independentemente das combinações hormonais testadas verificou-se a formação de calos friáveis (2 a 20 mm de diâmetro) em 90% dos entrenós usados como explantes. No entanto, os tratamentos testados não foram capazes induzir calos ou gemas em raízes e em discos foliares. O estudo anatômico revelou a formação de meristemóides nas regiões mais externa e mais interna dos calos. Os resultados obtidos poderão servir de base para novos testes de indução de calos na espécie.The objective of this research was to evaluate the organogenic potential of internodes, leaf discs and roots of Brosimum gaudichaudii using 12 different combinations of the plant growth regulators 6-benzylaminopurine and naphthalene acetic acid in MS medium (half strength), solid medium (6.5 g agar) and sucrose medium (20 g.L-1). Regardless the hormonal combination tested, we observed the formation of friable calluses (2 - 20 mm wide) in 90% of the internode explants. However, the treatments were not able to induce callus or buds on roots and leaf discs. The anatomical analysis revealed meristemoid formation in the outer and inner regions of the calluses. The results may serve as the basis for further testing of callus induction in this species

In silico before in vivo: How to predict the heating efficiency of magnetic nanoparticles within the intracellular space

This work aims to demonstrate the need for in silico design via numerical simulation to produce optimal Fe 3 O 4 -based magnetic nanoparticles (MNPs) for magnetic hyperthermia by minimizing the impact of intracellular environments on heating efficiency. By including the relevant magnetic parameters, such as magnetic anisotropy and dipolar interactions, into a numerical model, the heating efficiency of as prepared colloids was preserved in the intracellular environment, providing the largest in vitro specific power absorption (SPA) values yet reported. Dipolar interactions due to intracellular agglomeration, which are included in the simulated SPA, were found to be the main cause of changes in the magnetic relaxation dynamics of MNPs under in vitro conditions. These results pave the way for the magnetism-based design of MNPs that can retain their heating efficiency in vivo, thereby improving the outcome of clinical hyperthermia experiments

Low-Dimensional Assemblies of Magnetic MnFe2O4 Nanoparticles and Direct In Vitro Measurements of Enhanced Heating Driven by Dipolar Interactions: Implications for Magnetic Hyperthermia

Magnetic fluid hyperthermia (MFH), the procedure of raising the temperature of tumor cells using magnetic nanoparticles (MNPs) as heating agents, has proven successful in treating some types of cancer. However, the low heating power generated under physiological conditions makes it necessary a high local concentration of MNPs at tumor sites. Here, we report how the in vitro heating power of magnetically soft MnFe2O4 nanoparticles can be enhanced by intracellular low-dimensional clusters through a strategy that includes: (a) the design of the MNPs to retain Neel magnetic relaxation in high-viscosity media, and (b) culturing MNP-loaded cells under magnetic fields to produce elongated intracellular agglomerates. Our direct in vitro measurements demonstrated that the specific loss power (SLP) of elongated agglomerates (SLP = 576 +/- 33 W/g) induced by culturing BV2 cells in situ under a dc magnetic field was increased by a factor of 2 compared to the SLP = 305 +/- 25 W/g measured in aggregates freely formed within cells. A numerical mean-field model that included dipolar interactions quantitatively reproduced the SLPs of these clusters both in phantoms and in vitro, suggesting that it captures the relevant mechanisms behind power losses under high-viscosity conditions. These results indicate that in situ assembling of MNPs into low-dimensional structures is a sound possible way to improve the heating performance in MFH

Controlling the dominant magnetic relaxation mechanisms for magnetic hyperthermia in bimagnetic core-shell nanoparticles

We report a simple and effective way to control the heat generation of a magnetic colloid under alternate magnetic fields by changing the shell composition of bimagnetic core-shell Fe 3 O 4 /Zn x Co 1-x Fe 2 O 4 nanoparticles. The core-shell structure constitutes a magnetically-coupled biphase system, with an effective anisotropy that can be tuned by the substitution of Co 2+ by Zn 2+ ions in the shell. Magnetic hyperthermia experiments of nanoparticles dispersed in hexane and butter oil showed that the magnetic relaxation is dominated by Brown relaxation mechanism in samples with higher anisotropy (i.e., larger concentration of Co within the shell) yielding high specific power absorption values in low viscosity media as hexane. Increasing the Zn concentration of the shell, diminishes the magnetic anisotropy, which results in a change to a Néel relaxation that dominates the process when the nanoparticles are dispersed in a high-viscosity medium. We demonstrate that tuning the Zn contents at the shell of these exchange-coupled core/shell nanoparticles provides a way to control the magnetic anisotropy without loss of saturation magnetization. This ability is an essential prerequisite for most biomedical applications, where high viscosities and capturing mechanisms are present. This journal i

High-resolution monitoring of diffuse (sheet or interrill) erosion using structure-from-motion

Sheet erosion is common on agricultural lands, and understanding the dynamics of the erosive process as well as the quantification of soil loss is important for both soil scientists and managers. However, measuring rates of soil loss from sheet erosion has proved difficult due to requiring the detection of relatively small surface changes over extended areas. Consequently, such measurements have relied on the use of erosion plots, which have limited spatial coverage and have high operating costs. For measuring the larger erosion rates characteristic of rill and gully erosion, structure-from-motion (SfM) photogrammetry has been demonstrated to be a valuable tool. Here, we demonstrate the first direct validation of UAV-SfM measurements of sheet erosion using sediment collection data collected from erosion plots. Three erosion plots (12 m × 4 m) located at Lavras, Brazil, with bare soil exposed to natural rainfall from which event sediment and runoff was monitored, were mapped during two hydrological years (2016 and 2017), using a UAV equipped with a RGB camera. DEMs of difference (DoD) were calculated to detect spatial changes in the soil surface topography over time and to quantify the volumes of sediments lost or gained. Precision maps were generated to enable precision estimates for both DEMs to be propagated into the DoD as spatially variable vertical uncertainties. The point clouds generated from SfM gave mean errors of ~2.4 mm horizontally (xy) and ~1.9 mm vertically (z) on control and independent check points, and the level of detection (LoD) along the plots ranged from 1.4 mm to 7.4 mm. The soil loss values obtained by SfM were significantly (p < 0.001) correlated (r 2 = 95.55%) with those derived from the sediment collection. These results open up the possibility to use SfM for erosion studies where channelized erosion is not the principal mechanism, offering a cost-effective method for gaining new insights into sheet, and interrill, erosion processes

Chemoenzymatic synthesis of (S)-Pindolol using lipases

A straightforward chemoenzymatic synthesis of (S)-Pindolol has been developed. The key step involved the enzymatic kinetic resolution of rac-2-acetoxy-1-(1H-indol-4-yloxy)-3-chloropropane with lipase from Pseudomonas fluorescens via hydrolytic process to obtain enantiomerically enriched halohydrin (2S)-1-(1H-indol-4-yloxy)-3-chloro-2-propanol (96% ee) and (2R)-2-acetoxy-1-(1H-indol-4-yloxy)-3-chloropropane (97% ee). The latter was subjected to a hydrolysis reaction catalyzed by Candida rugosa leading to (2R)-1-(1H-indol-4-yloxy)-3-chloro-2-propanol (97% ee), followed by a reaction with isopropylamine, producing (S)-Pindolol (97% ee) in quantitative yield

Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors

Quasiclassic Uzadel equations for two-band superconductors in the dirty limit with the account of both intraband and interband scattering by nonmagnetic impurities are derived for any anisotropic Fermi surface. From these equations the Ginzburg-Landau equations, and the critical temperature $T_c$ are obtained. An equation for the upper critical field, which determines both the temperature dependence of $H_{c2}(T)$ and the orientational dependence of $H_{c2}(\theta)$ as a function of the angle $\theta$ between ${\bf H}$ and the c-axis is obtained. It is shown that the shape of the $H_{c2}(T)$ curve essentially depends on the ratio of the intraband electron diffusivities $D_1$ and $D_1$, and can be very different from the standard one-gap dirty limit theory. In particular, the value $H_{c2}(0)$ can considerably exceed $0.7T_cdH_{c2}/dT_c$, which can have important consequences for applications of $MgB_2$. A scaling relation is proposed which enables one to obtain the angular dependence of $H_{c2}(\theta)$ from the equation for $H_{c2}$ at ${\bf H}\| c$. It is shown that, depending on the relation between $D_1$ and $D_2$, the ratio of the upper critical field $H_{c2}^\|/H_{c2}^\perp$ for ${\bf H}\| ab$ and ${\bf H}\perp ab$ can both increase and decrease as the temperature decreases. Implications of the obtained results for $MgB_2$ are discussed