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•Biochar is a by-product of biomass pyrolysis for energy production.•Biochar can disperse (poly)metallic nanoparticles, nanoalloy and metal oxides.•Biochar used as support increases ...the catalyst stability and reactivity.•Biochar used as catalyst support minimizes leaching and allows catalyst re-use.•The biochar support can be used in fine chemicals synthesis and tar reforming.
The transformation and use of the biomass are of fundamental energetic and ecological interest. The general objective of this review is to provide an overview of biochar (a major biomass product) as a support for nanocatalysts and other reagents, its mode of coordination and activation with nanoparticles and applications. This includes the physico-chemical characteristics of biochar, the advances in its production processes, and its activation and functionalization in order to improve its physical and chemical characteristics and applications as support in catalysis and environmental decontamination. Biochar is a by-product produced by carbonization of biomass. In this process, the products of interest are syngas and bio-oil, due to their high calorific value and their diverse applications. However, biochar has interesting characteristics. It can be used as support, allowing to disperse nanoparticles of the catalysts, such as those of the transition metals: Fe, Ag, Ni, Pd, etc., bimetallic compositions such as Ru/Re, Fe/Ni, etc. and metal oxides such as Fe3O4, CO3O4, CuO, TiO2, etc., increasing the reactivity of the system, minimizing the leaching of the catalysts and allowing their re-use. These materials can be employed in the degradation of contaminants in aqueous systems, soil and sediments, tar reforming reactions and synthesis of fine chemicals. This review will serve as the basis for new research aiming to add value to this important resource.
This study explores the stabilization by niobic acid, of Pt, Ni, Pd, and Au nanoparticles (NPs) for the efficient microheterogeneous catalysis of NaBH
4
hydrolysis for hydrogen production. Niobic ...acid is the most widely studied Nb
2
O
5
polymorph, and it is employed here for the first time for this key reaction relevant to green energy. Structural insights from XRD, Raman, and FTIR spectroscopies, combined with hydrogen production data, reveal the role of niobic acid's Brønsted acidity in its catalytic activity. The supported NPs showed significantly higher efficiency than the non-supported counterparts regarding turnover frequency, average hydrogen production rate, and cost. Among the tested NPs, PtNPs and NiNPs demonstrate the most favorable results. The data imply mechanism changes during the reaction, and the kinetic isotope assay indicates a primary isotope effect. Reusability assays demonstrate consistent yields over five cycles for PtNPs, although catalytic efficiency decreases, likely due to the formation of reaction byproducts.
This study explores the stabilization by niobic acid, of Pt, Ni, Pd, and Au nanoparticles (NPs) for the efficient microheterogeneous catalysis of NaBH
4
hydrolysis for hydrogen production.
Africanized and wild bees are sensitive to synthetic insecticides, but may not be sensitive to botanical extracts. In this work, we evaluated the toxicity of botanical extracts with homemade ...preparations used in agroecological crops and their constituents on the bees
Apis mellifera
and
Partamona helleri
. Toxicity bioassays of adult bees were done by means of oral exposure and ingestion, using the insecticide imidacloprid as a positive control. Dietary consumption, respiration rate and bee flight were evaluated as sublethal parameters. Although some extracts were toxic to bees, survival was always higher compared to the results obtained with the imidacloprid, which was lethal to 100% of bees. In dietary consumption,
P. helleri
consumed less (5 mg/bee) in 3 h than
A. mellifera
(11 mg/bee), and
P. helleri
consumed less (7 mg/bee) in 24 h than
A. mellifera
(22 mg/bee). There was no difference in consumption of food containing plant extracts or food containing water only. We did not detect any adverse effects of the botanical extracts on bee respiration rates or flight. The major constituent of
N. tabacum
is nicotine (8.4–15.1%), in
A. americana
it is β-caryophyllene (11.3%), and in
A. colubrina
, lupeol (12.2%). Imidacloprid and nicotine were more toxic to bees (LC
50
≤ 1.3 and LC
50
≤ 44.3). Botanical extracts were selective to
A. mellifera
and the native bee
P. helleri
, and therefore, have the potential for ecofriendly pest control.
Infectious diseases that cause hemolysis are among the most threatening human diseases, because of severity and/or global distribution. In these conditions, hemeproteins and heme are released, but ...whether heme affects the inflammatory response to microorganism molecules remains to be characterized. Here, we show that heme increased the lethality and cytokine secretion induced by LPS in vivo and enhanced the secretion of cytokines by macrophages stimulated with various agonists of innate immune receptors. Activation of nuclear factor κB (NF-κB) and MAPKs and the generation of reactive oxygen species were essential to the increase in cytokine production induced by heme plus LPS. This synergistic effect of heme and LPS was blocked by a selective inhibitor of spleen tyrosine kinase (Syk) and was abrogated in dendritic cells deficient in Syk. Moreover, inhibition of Syk and the downstream molecules PKC and PI3K reduced the reactive oxygen species generation by heme. Our results highlight a mechanism by which heme amplifies the secretion of cytokines triggered by microbial molecule activation and indicates possible pathways for therapeutic intervention during hemolytic infectious diseases.
Eucalypts are cultivated worldwide, but little is known about their status as hosts of root-knot nematodes (RKN) (
spp.). Moreover, information is scarce regarding the nature of the damage caused by ...RKN to eucalypt seedlings and trees. To investigate these aspects, we separately inoculated
,
and
in seedlings of the world’s most cultivated eucalypts:
,
,
,
,
,
, and the hybrid
×
. After six months of greenhouse cultivation, we assessed nematode reproduction and variables that expressed the seedlings’ shoot and root growth. We observed a diverse pattern of host statuses to RKN among the eucalypts, and all three
species reduced (
< 0.05) the root system mass, volume and length of
,
and the hybrid
×
. Our results reaffirm previous reports indicating that RKN can delay the growth of seedlings in nurseries, who should thus adopt appropriate sanitary measures to avoid RKN establishment and spread. Moreover, the damage caused by RKN to eucalypts after just six months of cultivation suggests that the growth of eucalypt trees may be affected over the course of several years of cultivation.
The induced expression of nitric oxide synthase (iNOS) controls the intracellular growth of Leishmania in infected macrophages. Histones deacetylases (HDACs) negatively regulate gene expression ...through the formation of complexes containing transcription factors such as NF‐κB p50/50. Herein, we demonstrated the occupancy of p50/p50_HDAC1 to iNOS promoter associated with reduced levels of H3K9Ac. Remarkably, we found increased levels of HDAC1 in L. amazonensis‐infected macrophages. HDAC1 upregulation was not found in L. major‐infected macrophages. The parasite intracellular load was reduced in HDAC1 knocked‐down macrophages, which presented increased nitric oxide levels. HDAC1 silencing led to the occupancy of CBP/p300 to iNOS promoter and the rise of H3K9Ac modification. Importantly, the immunostaining of skin samples from hiporeactive cutaneous leishmaniasis patients infected with L. amazonensis, revealed high levels of HDAC1. In brief, L. amazonensis induces HDAC1 in infected macrophages, which contribute to parasite survival and is associated to hiporeactive stage found in L. amazonensis infected patients.
Leishmania amazonensis infection induces NF‐κB p50/p50 and increases the nuclear levels of HDAC1 in macrophages. In the nucleus, p50/50 binds to nk promoter sequences and recruits HDAC1, forming a repression complex leading to H3K9 deacetylation and consequent iNOS promoter silencing. The absence of Nitric Oxide production favors the amastigote growth.
In this work the development and validation of analytical methodology for determination of copper in sugarcane spirit samples is carried out. The digital image based (DIB) method was applied along ...with spot test from the colorimetric reaction employing the RGB color model. For the determination of copper concentration, it was used the cuprizone - a bidentate organic reagent - which forms with copper a blue chelate in an alkaline medium. A linear calibration curve over the concentration range from 0.75 to 5.00mgL−1 (r2=0.9988) was obtained and limits of detection and quantification of 0.078mgL−1 and 0.26mgL−1 were acquired, respectively. For the accuracy studies, recovery percentages ranged from 98 to 104% were obtained. The comparison of cooper concentration results in sugar cane spirits using the DIB method and Flame Atomic Absorption Spectrometry as reference method showed no significant differences between both methods, which were performed using the paired t-test in 95% of confidence level. Thus, the spot test method associated with DIB allows the use of devices as digital cameras and smartphones to evaluate colorimetric reaction with low waste generation, practicality, quickness, accuracy, precision, high portability and low-cost.
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•A portable system with cheap materials to obtain images was developed•The system was employed in the determination of copper(II) in cachaça•The method has low reagent consumption with 600µL per spot•The fast response, low-cost and handle-easy devices are very attractive for smallholders
Inclusion complexes (ICs) of 2-hydroxypropyl-β-cyclodextrin with the essential oil (EO) from Seculo XXI cultivar of
were prepared using kneading (KN) and freeze-drying (FD) methods. The resulting ICs ...clusters have a nanometric size, with a diameter of approximately 80 and 40 nm for KN and FD, respectively. Complexation efficiency was 80.3% and 50.8% for KN and FD methods, respectively. The larvicidal activity of the EO in DMSO on
had LC
and LC
values of 51.49 and 64.51 µg mL
, respectively. For the KN method, the toxicity corresponded to 77.54 and 107.29 µg mL
for LC
and LC
, respectively. FD method demonstrated toxicity at concentrations above 600 µg mL
. Thus, ICs enable the use of EO in breeding sites for
, thus being potential products to be commercially exploited.
Recent studies have shown Cu(0) as a promising material for the removal of organic and inorganic pollutants. However, there is no review addressing the studies performed. This fact may be related to ...the toxicity of the particles and the copper released in solution that has not motivated researchers, which entails in a reduced number of publications. However, studies point out how to solve the problem of Cu deposition in support materials. In this work, a detailed review of Cu(0) applications was performed. The specific focus was the reaction mechanisms related to adsorption, oxidation, and reduction processes. Initially, the resources that allow the understanding of the reaction mechanism, such as characterization techniques and the experimental conditions for investigation of the species involved in the process, were presented. The studies were evaluated separately, showing the mechanisms involved only with the application of Cu(0) in pure and isolated form and in association with oxidizing or reductive agents, combined with irradiation sources and ultrasonic waves and in the form supported in polymer matrices. It was verified that by the proposed reaction mechanisms, the exclusive participation of Cu(0), being the removal process, explained only by the redox behavior of copper. Therefore, the review showed the need for future research regarding the redox behavior of the contaminants.
Quality is an increasingly present concept nowadays, so meeting the customers’ needs, who buy and use products and hire services, becomes essential. For laboratories, the concept is applied to the ...reliability and traceability of the results produced and presents itself not only to meet the customer’s needs, but also to allow the signing of agreements in the international trade. The concept of Quality in a laboratory can be carried out from the elaboration of a Quality Management System (QMS). To this end, the normative document ISO/IEC 17025, internationally accepted, has been changing over the years aimed at instructing the elaboration of a management system which proves the technical capacity of testing and calibration laboratories and guides the generation of reliable results. The document is in its third version as a standard, the most current one published in 2017, and it presents requirements to achieve the proposed objective and the quality assurance. In the face of the importance of these concepts and the unquestionable need of laboratories to provide reliable and traceable results, this article presents the norm history and its most recent changes. Its intent is support laboratories whose objective is to implement a QMS according to this normative reference
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