Optimization of Operational Parameters and Bath Control for Electrodeposion of Ni-Mo-B Amorphous Alloys

A otimização de parâmetros operacionais de um processo de eletrodeposição de camada metálica amorfa de liga níquel-molibdênio contendo boro sobre um catodo utilizando um banho de sulfato de níquel, molibdato de sódio, fosfato de boro, citrato de sódio, 1-docecilsulfato de sódio e hidróxido de amônio para pH 9,5 foi estudada. Estudos detalhados sobre o efeito da temperatura do banho, agitação mecânica, densidade de corrente catódica e formato de ânodo conduziu às condições ótimas para obtenção de depósitos de ligas satisfatórias. A mais alta eficiência catódica, cerca de 69% para ânodo cilíndrico e 64% para ânodo retengular de platina, foi obtida a 80 o C, 15 rpm e 100 mA cm -2 . Um método voltamétrico para controle e monitoramento automático do processo foi proposto. Optimization of operational parameters of an electrodeposition process for deposition of boroncontaining amorphous metallic layer of nickel-molybdenum alloy onto a cathode from an electrolytic bath having nickel sulfate, sodium molybdate, boron phosphate, sodium citrate, sodium-1-dodecylsulfate and ammonia for pH adjustments to 9.5 has been studied. Detailed studies of the efects on bath temperature, mechanical agitation, cathode current density and anode format have led to optimum operational conditions for obtaining satisfactory alloy deposits. The highest cathode current efficiency for deposition of the alloy was about 69% for cylindrical and 64% for rectangular platinum anode while working at bath temperature 80 o C, cathode rotation 15 rpm and cathode current density 100 mA cm -2 . A voltammetric method for automatic monitoring and control of the process was proposed

USING REMOTELY PILOTED AIRCRAFT (RPA) IMAGERY TO MAP THE PROFITABILITY OF COTTON CROPS

ABSTRACT The goal of this paper was to apply a method for the delineation of vegetation homogeneous zones (HZs) to map the profitability of cotton ( Gossypium sp.) using NDVI (Normalized Difference Vegetation Index) data from RPA imagery. Two irrigated cotton crops, at the FAU (103 ha) and FRP farms (106 ha), located in the western region of Bahia State, Brazil, were studied. The NDVI images were classified into three HZs: “high”, “medium” and “low” plant vigor; using the k-means clustering method. In each HZ the yield was measured, and the profitability estimated. In FAU we found that the lower the HZ’s NDVI values, the lower its profitability, because there was profit in the “high vigor” HZ, of US$829.40 ha-1, and loss in the “low vigor” HZ, of about US$ ‒1.256.09 ha-1 (‒251.44% compared with the “high vigor”). In the FRP plantation, the lower the NDVI values, the lower the loss of the plantation, as there were losses in all HZs: from “high” to “low vigor” HZ, the percentage difference in profitability was ‒343.43%. Thus, the use of a low-cost modified near-infrared Canon S100 on an RPA enabled the mapping of crop profitability, aiding the search for the factors behind yield variability

Lattice dynamics localization in low-angle twisted bilayer graphene

A low twist angle between the two stacked crystal networks in bilayer graphene enables self-organized lattice reconstruction with the formation of a periodic domain. This superlattice modulates the vibrational and electronic structures, imposing new rules for electron-phonon coupling and the eventual observation of strong correlation and superconductivity. Direct optical images of the crystal superlattice in reconstructed twisted bilayer graphene are reported here, generated by the inelastic scattering of light in a nano-Raman spectroscope. The observation of the crystallographic structure with visible light is made possible due to lattice dynamics localization, the images resembling spectral variations caused by the presence of strain solitons and topological points. The results are rationalized by a nearly-free-phonon model and electronic calculations that highlight the relevance of solitons and topological points, particularly pronounced for structures with small twist angles. We anticipate our discovery to play a role in understanding Jahn-Teller effects and electronic Cooper pairing, among many other important phonon-related effects, and it may be useful for characterizing devices in the most prominent platform for the field of twistronics.Comment: 9 pages, 8 figure

Microbial community profile and water quality in a protected area of the caatinga biome

The Caatinga is a semi-arid biome in northeast Brazil. The Paraguaçú River is located in the Caatinga biome, and part of its course is protected by the National Park of Chapada Diamantina (PNCD). In this study we evaluated the effect of PNCD protection on the water quality and microbial community diversity of this river by analyzing water samples obtained from points located inside and outside the PNCD in both wet and dry seasons. Results of water quality analysis showed higher levels of silicate, ammonia, particulate organic carbon, and nitrite in samples from the unprotected area compared with those from protected areas. Pyrosequencing of the 16S rRNA genes revealed that Burkholderiales was abundant in samples from all three sites during both seasons and was represented primarily by the genus Polynucleobacter and members of the Comamonadaceae family (e.g., genus Limnohabitans). During the dry season, the unprotected area showed a higher abundance of Flavobacterium sp. and Arthrobacter sp., which are frequently associated with the presence and/or degradation of arsenic and pesticide compounds. In addition, genes that appear to be related to agricultural impacts on the environment, as well as those involved in arsenic and cadmium resistance, copper homeostasis, and propanediol utilization, were detected in the unprotected areas by metagenomic sequencing. Although PNCD protection improves water quality, agricultural activities around the park may affect water quality within the park and may account for the presence of bacteria capable of pesticide degradation and assimilation, evidencing possible anthropogenic impacts on the Caatinga

Transient Changes in Bacterioplankton Communities Induced by the Submarine Volcanic Eruption of El Hierro (Canary Islands)

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Avaliação de laboratórios brasileiros na determinação de alguns parâmetros de qualidade de biocombustíveis

This work shows the results of a Proficiency Testing performed by a partnership between INMETRO and ANP. The performance of 49 Brazilian laboratories (using the z-score statistical test) in determining 10 quality parameters of ethanol fuel and biodiesel was evaluated. The certified reference values were provided by INMETRO, allowing a more rigorous assessment of the laboratories. For hydrous ethanol, the acidity parameter showed the lowest number of laboratories with satisfactory results (48%), while 85% of the laboratories presented satisfactory results for ethanol content. For biodiesel, the percentage of laboratories with satisfactory results ranged from 46% (kinematic viscosity) to 92% (acid number)