Cytotoxic effects of extract of Acmella oleraceae (Jambú) in Rhipicephalus microplus females ticks

The present study analyzed the effects of different concentrations of the hexane extract of A. oleraceae (HEAO) (Jambú) on the germ cells of semi‐engorged Rhipicephalus microplus female ticks, through a morpho‐histological study, evaluating the effectiveness of the extract in the genesis of the individuals. To perform this analysis, 100 semi‐engorged females were divided into five groups with 20 individuals each: groups I and II, respectively constituted by distilled water control and 50% ethanol + 1% DMSO, and groups III, IV, and V constituted by treatment with HEAO in the concentrations of 12.5, 25.0 and 50.0 mg/mL, respectively. All the ticks were immersed in the different concentrations of the extract or in distilled water for 5 minutes, dried and conditioned in BOD incubator for 7 days. The individuals of the treatment groups revealed the action of this extract showing alterations in the germ cells of the females from the different groups when compared with those from the groups I and II (control groups). These alterations were mainly related to the size and shape of the oocytes; number of yolk granules; presence, number, size and location of vacuoles in the cytoplasm of all the germ cells; and the presence of nuclear alterations in these cells as well. Thus, it was demonstrated that the concentrations of HEAO affected the germ cells of R. microplus ticks. The effects of the extract are similar to those caused by renowned and efficient chemical products used to control these ticks. Microsc. Res. Tech. 79:744–753, 2016. © 2016 Wiley Periodicals, Inc.     

Models and modelling for process limits in metal forming

Modelling of metal forming processes is an essential task of production engineering. Due to the latest technological developments, a huge variety of models is already available and extending continuously. Thus, it is important to find a suitable model. This paper gives an overview on the common classification and characterization of modelling and models in metal forming, as well as introduces a model selection procedure. Based on this classification, various relevant process limits for metal forming are investigated regarding existing models. The conclusion of the paper shows open topics as well as upcoming challenges in modelling process limits in metal forming.     

Volatilization kinetics of chromium oxide,manganese oxide,and manganese chromium spinel at high temperatures in environments containing water vapor

Performance degradation of solid oxide fuel cells due to chromium volatilization is a well‐investigated issue in the literature. Therefore, retention coatings were developed to distinctly reduce the chromium volatilization. One approach was by alloying with manganese to ferritic steels to form manganese chromium spinel which is reported to decrease chromium volatilization by 61–75%. In the present paper, the volatilization rates of pure manganese chromium spinel ceramics were examined as well as those of the two oxides forming this spinel—pure chromium oxide and pure manganese oxide—in synthetic air containing 10% water vapor (high p(O₂)) and argon/hydrogen containing 10% water vapor (low p(O₂)) at 850°C, 950°C, and 1,050°C. Chromium oxide showed higher volatilization rates in high p(O₂), whereas manganese oxide demonstrated higher volatilization rates in low p(O₂). Contradictory to the literature, manganese chromium spinel displayed the highest volatilization rates in both atmospheres and nonlinear kinetics behavior. This deviation from linear behavior can be attributed to diffusion‐controlled volatilization in high p(O₂).     

Fabrication of nanostructure via self-assembly of nanowires within the AAO template

The novel nanostructures are fabricated by the spatial chemical modification of nanowires within the anodic aluminum oxide (AAO) template. To make the nanowires better dispersion in the aqueous solution, the copper is first deposited to fill the dendrite structure at the bottom of template. During the process of self-assembly, the dithiol compound was used as the connector between the nanowires and nanoparticles by a self-assembly method. The nanostructures of the nano cigars and structure which is containing particles junction are characterized by transmission electron microscopy (TEM). These kinds of novel nanostructure will be the building blocks for nanoelectronic and nanophotonic devices.      

Measurement of the local intensities of segregation with the tomographical dual wavelength photometry

The newly developed tomographical dual wavelength photometry enables the measurement of the local intensity of segregation at a multitude of points inside the stirred vessel. This is done by injecting a mixture of an inert and a reacting dye into the vessel. The inert dye serves as a tracer for the macromixing, whereas the vanishing of the reacting dye shows the micromixing. The concentration fields of the dyes are measured simultaneously by transluminating the vessel from three directions with superimposed laser beams of different wavelength. The light absorption by the dyes is measured with CCD-cameras and these projections are used for the tomographic reconstruction of the concentration fields. Low Reynolds number measurements with a Rushton turbine show better macro- and micromixing for a dye injection closer to the stirrer shaft compared to a position closer to the main vortex.     

Structure and performance of soy hull carbon adsorbents as affected by pyrolysis temperature

Soy hulls were evaluated as a source of adsorbent carbon for vegetable oil processing. Soy hull carbon was prepared by burning ground soy hulls (<100 mesh) at 300, 400, 500, or 700°C in a muffle furnace. The structure of the soy hull carbon was studied by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Crude soy oil was processed with the soy hull carbon products at 2% (w/w) in the laboratory under commercial bleaching conditions. Free fatty acids (FFA), peroxide value, phospholipid phosphorus (PLP), and lutein content of the treated samples were determined. SEM of the samples revealed particle size ranging from 1 to 2 mm. Increasing the pyrolysis temperature resulted in expansion and disruption of cellular structure. FTIR spectra of the carbon samples showed major differences in peak intensities at 3600 to 3200, 1600, and 1450 cm⁻¹ due to pyrolysis temperature. XRD revealed a predominantly amorphous structure with increasing pyrolysis temperature, which also resulted in an increased alkaline surface. Soy hull carbon decreased the FFA content of oil samples compared to that of crude oil, with the exception of carbon that was prepared at 300°C (P<0.05). A similar trend was observed in the adsorption of peroxides; however, no trends were observed in the adsorption of PLP or lutein. Higher pyrolysis temperature decreased randomness of the carbon and imparted a certain degree of structural order. This may be beneficial in providing physical access of the adsorbate molecule to the adsorbent surface.     

On the importance of a connected hard-phase skeleton for the creep resistance of Mg alloys

The low density of Mg alloys renders them attractive for lightweight constructions. However, creep resistance remains an important limitation of Mg alloys for, for example, automotive power train applications. To gain a more detailed understanding of the correlation between microstructure and creep properties in die-castable Mg alloys, AZ91 alloys with nominal additions of 0, 1, 3, and 5 mass% Ca and the commercial alloy MRI 230D have been investigated. Creep tests show an increase in creep strength with increasing Ca addition and increasing cooling rate. Scanning electron microscopy reveals that this is correlated with an increasing interconnectivity of the intermetallic phase skeleton (in addition to the effect of small precipitates within the α-Mg matrix found in the case of MRI 230D). A simple isostrain composite analysis illustrates that a more interconnected skeleton shields more load from the matrix. Precipitation hardening can additionally strengthen the matrix, and thus the combination of both design approaches results in the highest observed creep resistance.     

Behavior of copper-containing high-entropy alloys in harsh metal-dusting environments

Metal dusting is still an unresolved issue at high temperatures. Currently, two material-related strategies to mitigate metal dusting are described in the literature. On the one hand, highly alloyed materials are used, which contain large amounts of protective oxide-forming elements, such as Cr, Al, and Si. The second mitigation strategy is based on inhibiting the catalytic effect of Fe, Ni, and Co. These elements all strongly catalyze the formation of solid carbon from the gas phase. Combining the catalytic protection of Cu alloying for metal dusting with protection by a classical alumina/chromia barrier is a native feature that high-entropy alloys (HEAs) can offer. In this study, the behavior of different equiatomic HEAs with and without Al and/or Cu are studied when exposed at 620°C in a highly aggressive metal-dusting environment.     

Improved preparative electrochemical oxidation of d-glucose to d-glucaric acid

The 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO) mediated electrochemical oxidation of d-glucose to d-glucaric acid on a synthetically useful scale is reported. Using TEMPO and a graphite felt anode combined with a stainless steel cathode, d-glucose was oxidized under different conditions (pH, temperature, co-oxidant), and the reaction outcomes were analyzed. Optimized conditions for such oxidation are provided along with few new interesting results unique to this reaction, such as the appearance of a novel triacid.     

Action of andiroba oil (Carapa guianensis) on Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi‐engorged females: Morphophysiological evaluation of reproductive system

Because of the increasing medical‐veterinary importance of ticks, the development of alternative control methods, less aggressive to the host and the environment has become the target of several researches. In this sense, the present study analyzed the action of different concentrations (5, 10, and 20%) of andiroba seed oil (Carapa guianensis) on the reproductive system of Rhipicephalus sanguineus females, through histochemical techniques and the quantification of the reproductive efficiency index. The results showed that andiroba oil is a potent natural agent, able to cause several changes in the oocytes of this species, impairing the reproductive success, once this natural product induces great physiological changes in the oocytes in all development stages, such as drastic reduction in proteins, polysaccharides, and lipids in these cells, and these components are essential for the viability of the embryo. In addition, it was observed that this product stimulate the oviposition, mainly at the concentration of 20%. This higher production of eggs represents a defense mechanism developed by the organism in order to ensure the reproductive success of the species, even in the presence of the toxic agent. However, the results obtained suggested that the laid eggs would not be viable, due to the great changes undergone by the oocytes. Thus, the present study showed that the use of this vegetal product would be an alternative way to control the ticks, bringing benefits similar to the ones obtained through the use of synthetic acaricides; however, with less damage to nontarget organisms and the environment as well. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.