Methyltrioctylammonium methyl sulfate (TMA) and trimethyltetradecylammonium methyl sulfate (TTA) were synthetized as novel quaternary-ammonium-derived ionic liquids (ILs) in order to be evaluated as ...corrosion inhibitors (CIs) of API-X52 steel in 1 M HCl. Electrochemical techniques were used to evaluate the anticorrosive effect, finding that TMA and TTA worked as mixed-type CIs and inhibited the corrosion process depending on the temperature, immersion time and IL concentration, being remarkably effective at 40 °C, which was attributed to the high thermal stability of the methyl sulfate anions. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to elicit the chemical composition and surface morphology of steel in the presence of CIs whose adsorption processes involved strong electrostatic interactions between the metal, chloride ions, methyl sulfate anions and quaternary ammonium cations in the ILs. The results allowed the development of a corrosion inhibition mechanism.
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•Two ionic liquids derived from quaternary ammonium functioned as corrosion inhibitors with high inhibition efficiency.•The corrosion inhibitors presented a remarkable anticorrosive effect at 40 °C.•XPS confirmed the adsorption of the corrosion inhibitors on the metal surface.•Mechanism governing corrosion inhibition is discussed.
The application of herbicides may cause losses in the physiological quality of soybean seeds. 1 Introduction Weed interference can cause significant losses in soybean productivity, depending on the ...population and weed species (Fleck et al., 2007). Considering the increase in the number of resistant biotypes to glyphosate herbicide in soybean crop and its impact on agricultural production, new technologies and management strategies have been developed to prevent resistance and ensure adequate control of weeds. The objective of this study was to evaluate the physiological attributes of Enlist E3™ soybean seeds as a result of the herbicides application. 2 Material and Methods The field experiment was conducted in a randomized block design with four replications, at Mogi Mirim Research Center of Corteva Agriscience, in the city of Mogi Mirim/SP, during the 2016/17 harvest. ...results that demonstrate higher values of FGC can favor the crop in the initial stages of development, making it more competitive compared to weeds.
To study the factors associated with the occupational risks affecting coffee harvesters from Timbío, Cauca, Colombia.
This descriptive study assessed workplace conditions, aiming to design a ...mitigation proposal that would help alleviate the dangers currently facing the studied population. The data were collected through 19 visits to the coffee plantations. A survey to characterize workers and determine the presence of musculoskeletal lesions was applied; in addition, the Colombian Technical Guide (GTC 45, by its initials in Spanish) was consulted.
Coffee harvesting comes with several high priority risks, of which those that are biomechanical stand out. These are the result of strained positions, antigravity postures, repetitive movements, high physical effort, and the manual handling of heavy objects. Additionally, there are psychosocial risks attend the kind of contract, the low wages, the lack of social security, and the lack of affiliation with the occupational risk-management system. During the data collection, 18% of the workers reported having had an occupational accident while harvesting coffee.
The process for identifying danger and assessing risk established, for all the cases, a level 1 risk. According to the rating scale of the GTC 45, such a level is unacceptable. We concluded that it is necessary to take immediate measures to control the identified dangers. To improve the health of the members of the studied sample, we propose the implementation of an epidemiological surveillance system for musculoskeletal injuries.
Climate change is a major world-wide challenge to livestock production because food security is likely to be compromised by increased heat stress of the animals. The objective of this study was to ...characterize, using bioclimatic indexes, two livestock regions located in an arid zone of México, and to use this information to predict the impact of global warming on animal production systems of these regions located in the state of Baja California (México). A 5-year database (i.e., 2011 to 2015) consisting of about one million data points from two zones (i.e., coast, valley) from four meteorological stations in the north of Baja California were used. Bioclimatic indexes were constructed for the four types of livestock production systems most common in this region, being: dairy cattle, beef cattle, sheep, pigs. The temperature-humidity index (THI) thresholds used to classify heat stress were determined and scaled for each livestock species as: THIbeef and THIpig 74 units; THImilk 72 units; and THIsheep 23 units. Statistical differences between indices were detected (P < 0.01) during summer for the valley and coast zones as (THIbeef = 72.9 and 51.8; THImilk = 80.6 and 67.4; THIpigs = 83.9 and 65.2; THIsheep = 29.5 and 20.1 units). Coast zone weather did not suggest vulnerability of livestock production systems to heat stress at any time of the year, but heat stress risk during summer for valley zone dairy cattle, sheep and pigs was classified as severe, but lower for feedlot cattle. Prediction models showed significant adjustment just in the coastal zone for THImilk, THIsheep, and THIsheep, suggesting more impact of global warming during summer in the coastal zone. Use of management strategies to reduce heat load of domestic animals during summer in northern Baja California is essential to maintain their productivity, with more emphasis in the valley zone.
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•A 5-year database consisting of almost one million points of an arid zone were analyzed.•Bioclimatic indexes were estimated for dairy and beef cattle, as well as for sheep and pigs.•Temperature-humidity index (THI) thresholds for each livestock systems were calculated in two different zones of northwestern México.•Duration and intensity of heat stress were estimated to determine vulnerability of each livestock system on the valley zone.•Environmental strategies should be considered in the short term to avoid the negative effects.
Nanoscale plasmonic particles represent a crucial transformation on optical and electronic properties exhibited by advanced materials. Herein are reported remarkable interferometric optical effects ...with dependence on polarization for filtering or modulating electronic signals in multilayer nanostructures. Metallic nanoparticles were incorporated in randomly distributed networks of reduced graphene oxide by an in-situ vapor-phase deposition method. The polarization-selectable nonlinear optical absorption contribution on the photoconductivity of reduced graphene oxide decorated with gold nanoparticles was analyzed. Nanosecond pulses at 532 nm wavelength were employed in a two-wave mixing experiment to study photoconduction and nonlinear optical absorption in this nanohybrid material. The ablation threshold of the sample was measured in 0.4 J/cm
. Electrochemical impedance spectroscopy measurements revealed a capacitive response that can be enhanced by gold decoration in carbon nanostructures. A strong two-photon absorption process characterized by 5 × 10
m/W was identified as a physical mechanism responsible for the nonlinear photoconductive behavior of the nanostructures. Experimental shift of 1 MHz for the cutoff frequency associated with an electrical filter function performed by the sample in film form was demonstrated. Moreover, amplitude modulation of electronic signals controlled by the polarization of a two-wave mixing experiment was proposed. All-optical and optoelectronic nanosystems controlled by multi-photonic interactions in carbon-based materials were discussed. The key role of the vectorial nature of light in two-wave mixing experiments is a fascinating tool for the exploration of low-dimensional systems.
•Highly dispersed Pt nanoparticles were prepared on functionalized carbon nanotubes.•A simple and competitive vapor-phase method was employed.•Carbonyl groups were assumed to be responsible for ...assisted decomposition of Pt-acac.•Pt particles were highly dispersed because carbonyl groups served as reaction sites.•Particles of 2.3nm in size were highly dispersed even the high loading (27wt%Pt).
Highly dispersed Pt nanoparticles were prepared on functionalized multi-walled carbon nanotubes (f-MWCNTs) using a simple in situ vapor-phase method. The method consisted in two-step procedure in which an initial mixture of Pt precursor (Pt-acac) and f-MWCNTs was heated in a quartz tube reactor, first at 180°C and then at 400°C. Fourier transform infrared spectroscopy (FTIR–ATR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) were used to follow the chemical and structural transformations of mixture components during heating steps. The functionalization of MWCNTs with HNO3/H2SO4 solution resulted in formation of surface carbonyl groups. The FTIR–ATR and XRD results indicated that individual Pt-acac withstood heating at 180°C, whereas it was dissociated when heated in contact with f-MWCNTs at the same temperature. Thus, the functional carbonyl groups were found to be responsible for assisted decomposition of Pt-acac at 180°C. Since carbonyl groups served as reaction sites for decomposition of Pt-acac, the resulting particles were highly and homogeneously dispersed on the surface of MWCNTs even the relatively high metallic loading of 27wt%. TEM observations revealed that crystalline Pt particles exhibit narrow size distribution with a mean size of 2.3nm.
This work reports the morphological and photocatalytic hydrogen generation properties of CNT/Pt composites with and without functionalization by carboxylic/oxygen groups. The composites with and ...without functionalization were named f-CNT/Pt and CNT/Pt, respectively. Several f-CNT/Pt and CNT/Pt composites with different content of Pt NPs (from 0 to 30 wt%) were synthesized and analyzed by scanning electron microscopy (SEM). Those images revealed that the composites without functionalization presented higher agglomerations of Pt nanoparticles (NPs). Furthermore, the average sizes of the Pt NPs in the named f-CNT/Pt composites (2.3–2.9 nm) were lower than these in the CNT/Pt composites (2.5–3.1 nm). The hydrogen generation rates were also calculated from the decomposition of pure water under UV irradiation (365 nm) and found maximum values of 45.4 and 193.9 μmol·h−1 g−1 for the CNT/Pt and f-CNT/Pt composites (they contained 20 wt% of Pt NPs), respectively. Additional experiments for hydrogen generation were achieved using sodium sulfite as sacrificial agent; in this case, a maximum value of 13850 μmol·h−1 g−1 was obtained for the f-CNT/Pt composite. The f-CNT/Pt composites produced more hydrogen than the CNT/Pt composites because they presented higher content of defects; this was confirmed by the Raman spectra. We also showed that the Pt NPs acted as electron trap centers, which delayed the recombination of the photogenerated electrons and holes, this in turn, enhanced the hydrogen generation rates of the composites (the hydrogen generation was maximized by varying the content of Pt NPs deposited on the CNTs). The CNT/Pt composites presented here were simpler and easier to synthesize than the previous published ternary systems based on TiO2, CNTs and Pt NPs.
•CNT/Pt composites with 20 wt% of Pt NPs presented the highest hydrogen production.•Oxygen vacancy defects on the CNT/Pt composites enhanced the hydrogen generation.•Pt NPs on CNTs enhanced their light absorption, benefiting the hydrogen generation.
5-Fluorouracil (5-FU) is the most used chemotherapeutic agent in colorectal cancer. However, resistance to this drug is relatively frequent, and new strategies to overcome it are urgently needed. The ...aim of this work was to determine the antitumor properties of a supercritical fluid rosemary extract (SFRE), alone and in combination with 5-FU, as a potential adjuvant therapy useful for colon cancer patients. This extract has been recognized as a healthy component by the European Food Safety Authority (EFSA). The effects of SFRE both alone and in combination with 5-FU were evaluated in different human colon cancer cells in terms of cell viability, cytotoxicity, and cell transformation. Additionally, colon cancer cells resistant to 5-FU were used to assay the effects of SFRE on drug resistance. Finally, qRT-PCR was performed to ascertain the mechanism by which SFRE potentiates the effect of 5-FU. Our results show that SFRE displays dose-dependent antitumor activities and exerts a synergistic effect in combination with 5-FU on colon cancer cells. Furthermore, SFRE sensitizes 5-FU-resistant cells to the therapeutic activity of this drug, constituting a beneficial agent against both 5-FU sensitive and resistant tumor cells. Gene expression analysis indicates that the enhancement of the effect of 5-FU by SFRE might be explained by the downregulation of TYMS and TK1, enzymes related to 5-FU resistance.
•Nickel oxide decorated carbon nanotubes were prepared by chemical vapor deposition.•Contrast in photoconductivity phenomena in the nanohybrid was analyzed.•Electrical and nonlinear optical ...properties were evaluated.•A Wheatstone bridge sensor based metal/carbon nanostructures was proposed.
Within this work was explored the influence of nickel oxide decoration on the photoconductive effects exhibited by multiwall carbon nanotubes. Samples in thin film form were prepared by a chemical vapor deposition method. Experiments for evaluating the photo-response of the nanomaterials at 532 nanometers wavelength were undertaken. A contrasting behavior in the photoelectrical characteristics of the decorated nanostructures was analyzed. The decoration technique allowed us to control a decrease in photoconduction of the sample from approximately 100μmhos/cm to −600μmhos/cm. Two-wave mixing experiments confirmed an enhancement in nanosecond nonlinearities derived by nickel oxide contributions. It was considered that metallic nanoparticles present a strong responsibility for the evolution of the optoelectronic phenomena in metal/carbon nanohybrids. Impedance spectroscopy explorations indicated that a capacitive behavior correspond to the samples. A potential development of high-sensitive Wheatstone bridge sensors based on the optoelectrical performance of the studied samples was proposed.
Two hundred Holstein heifers were divided by hair coat color in black (
n
1
= 60), white (
n
2
= 62), and mixed (
n
3
= 78) to accomplish two objectives: (1) to compare physiological variables ...using an analysis of variance, and (2) to construct regression equations to predict rectal temperature. In each heifer, rectal temperature (RT), respiration frequency (RF), and body surface temperatures (obtained with infrared thermography in eye, nose, forehead, head, neck, ear, shoulder, flank, belly, leg, loin, rump, and vulva) were measured. Black heifers had more RF and RT (
P
< 0.01) than mixed and white coat heifers; white heifers had similar RT than mixed color heifers, but they exhibited less RF (
P
< 0.05). In general, black and mixed coat color heifers had higher BST (
P
< 0.01) than white heifers in the majority of the anatomical regions measured. For black coat heifers, the best regression model to predict RT included three predictor variables: RT = 35.59 − 0.013 (RH) + 0.045 (RF) + 0.019 (
T
Ear
);
R
2
= 71%. For white coat heifers, the best model included two predictor variables: RT = 35.29 + 0.035 (RF) + 0.033 (
T
Forehead
);
R
2
= 71%; and for mixed coat color heifers, the best model included two predictor variables: RT = 35.07 + 0.022 (RF) + 0.038 (
T
Head
);
R
2
= 44%. Heifers with dark hair coat color showed higher physiological constants than white heifers; the prediction of rectal temperature was more precise in heifers with well-defined hair coat color. Physiological and climatic variables, along with infrared thermography, represent an appropriate combination to predict rectal temperature in Holstein heifers with predominant white or black hair coat color.
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