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101.
Samuel Piña Jr. Diana M. Cedillo Carlos Tamez Nezhueyotl Izquierdo Jason G. Parsons Jose J. Gutierrez 《Tetrahedron letters》2014
Reported here is the reduction of aromatic nitro compounds using sodium borohydride and transition metal sulfides as catalysts. The reaction conditions were optimized using the reduction of nitrobenzene as a model reaction. The catalysts studied were iron sulfide (Fe3S4), copper sulfide (CuS), zinc sulfide (ZnS), cobalt sulfide (Co3S4), and nickel sulfide (NiS). The reduction was monitored using gas chromatography. Quantitative conversions were achieved using Co3S4 and NiS, representing a ten-fold increase in reactivity compared to the non-catalyzed reaction. Fe3S4 and ZnS had no apparent effect on the reduction of nitrobenzene while the reduction using CuS showed a marginal increase. The reduction method was applied to several aryl-nitro derivatives containing either electron-withdrawing or electron-donating groups. Halogen containing aryl-nitro compounds were reduced without dehalogenation. The reduction had no effect on other functional groups such as carboxylic acids, esters, amides, or alkenes, indicating that the reduction is highly chemoselective. 相似文献
102.
K. N. Suzuki E. C. Machado W. Machado A. V. B. Bellido L. F. Bellido J. A. Osso Jr. R. T. Lopes 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):357-361
Mangrove sediment cores sampled from Sepetiba Bay (SE Brazil) were covered with tidal water spiked with 75Se, 51Cr and 60Co to evaluate the removal efficiency of these radiotracers by underlying sediments. Variable time-evolution trends were observed along 115 h experiments, with significant differences between removal efficiencies of all radiotracers observed only after 70 h (51Cr > 60Co > 75Se). After an event of 60Co release back to overlying water, there was a general trend of lower 60Co removal than observed for other radiotracers during the period from 20 to 54 h. After this event, alternated periods of higher 60Co and higher 75Se removal trends were observed, attributed to behavioural differences expected for such anionic and cationic radiotracers. While 75Se and 51Cr showed uniform time-evolution curves, as typically found in the literature for most radiotracers, 60Co removal rates presented oscillations, probably due to sensitivity to changes in redox conditions within underlying sediments. Results evidenced the role of mangrove sediments as trace element sinks, which have implications for coastal water quality and for possible uses of such sediments in wastewater treatment systems. 相似文献
103.
Sergey V. Prikhodko Diana C. Rambaldi Andrew King Elizabeth Burr Vanessa Muros Ioanna Kakoulli 《Journal of Raman spectroscopy : JRS》2015,46(7):632-635
In the past decade Surface Enhanced Raman Scattering (SERS) has emerged as a powerful technique for the analysis of artistic, historical and archaeological material culture. However, the identification of organic compounds in complex samples using SERS can be challenging owing to the complexity in optimizing the adsorption of target analytes onto the plasmonic substrate and the difficulty to identify proper areas on the sample for robust SERS analysis using optical systems. Scanning electron microscopy (SEM) interfaced with Raman spectromicroscopy (μRS) provides an ideal hyphenated system to overcome the last challenge by: (1) evaluating the nanoparticles coverage/distribution on the sample and (2) locating suitable areas for successful and reproducible SERS analysis. In this paper we demonstrate the potential of a system interfacing SEM and μRS for single fiber, extractionless analysis in the characterization of dyes from reference collections and archaeological textiles. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
104.
Agnieszka Nowacka-Perrin Thomas Steglich Daniel Topgaard Diana Bernin 《Magnetic resonance in chemistry : MRC》2022,60(7):671-677
Convenience food products tend to alter their quality and texture while stored. Texture-giving food components are often starch-rich ingredients, such as pasta or rice. Starch transforms depending on time, temperature and water content, which alters the properties of products. Monitoring these transformations, which are associated with a change in mobility of the starch chain segments, could optimize the quality of food products containing multiple ingredients. In order to do so, we applied a simple and efficient in situ 13C solid-state magic angle spinning (MAS) NMR approach, based on two different polarization transfer schemes, cross polarization (CP) and insensitive nuclei enhanced by polarization transfer (INEPT). The efficiency of the CP and INEPT transfer depends strongly on the mobility of chain segments—the time scale of reorientation of the CH-bond and the order parameter. Rigid crystalline or amorphous starch chains give rise to CP peaks, whereas mobile gelatinized starch chains appear as INEPT peaks. Comparing 13C solid-state MAS NMR experiments based on CP and INEPT allows insight into the progress of gelatinization, and other starch transformations, by reporting on both rigid and mobile starch chains simultaneously with atomic resolution by the 13C chemical shift. In conjunction with 1H solid-state MAS NMR, complementary information about other food components present at low concentration, such as lipids and protein, can be obtained. We demonstrate our approach on starch-based products and commercial pasta as a function of temperature and storage. 相似文献
105.
Arajo Joana C. Teixeira Pilar Fangueiro Raul Ferreira Diana P. 《Cellulose (London, England)》2022,29(10):5659-5676
Cellulose - Core–shell nanoparticles (NPs) based on metal oxides, namely magnesium oxide (MgO) and silica (SiO2), are a fantastic alternative for natural fibers’ functionalization. In... 相似文献
106.
Cristian Mauricio Barreto Pinilla Nathalie Almeida Lopes Adriano Brandelli 《Molecules (Basel, Switzerland)》2021,26(12)
Encapsulation can be a suitable strategy to protect natural antimicrobial substances against some harsh conditions of processing and storage and to provide efficient formulations for antimicrobial delivery. Lipid-based nanostructures, including liposomes, solid lipid nanoparticles (SLNs), and nanostructured lipid nanocarriers (NLCs), are valuable systems for the delivery and controlled release of natural antimicrobial substances. These nanostructures have been used as carriers for bacteriocins and other antimicrobial peptides, antimicrobial enzymes, essential oils, and antimicrobial phytochemicals. Most studies are conducted with liposomes, although the potential of SLNs and NLCs as antimicrobial nanocarriers is not yet fully established. Some studies reveal that lipid-based formulations can be used for co-encapsulation of natural antimicrobials, improving their potential to control microbial pathogens. 相似文献
107.
Ana Margarida Silva Diana Pinto Iva Fernandes Victor de Freitas María de la Luz Cdiz-Gurrea Paulo Costa Cristina Delerue-Matos Francisca Rodrigues 《Molecules (Basel, Switzerland)》2021,26(8)
During kiwiberry production, different by-products are generated, including leaves that are removed to increase the fruit’s solar exposure. The aim of this work was to extract bioactive compounds from kiwiberry leaf by employing microwave-assisted extraction (MAE). Compatible food solvents (water and ethanol) were employed. The alcoholic extract contained the highest phenolic and flavonoid contents (629.48 mg of gallic acid equivalents (GAE) per gram of plant material on dry weight (dw) (GAE/g dw) and 136.81 mg of catechin equivalents per gram of plant material on dw (CAE/g dw), respectively). Oppositely, the hydroalcoholic extract achieved the highest antioxidant activity and scavenging activity against reactive oxygen and nitrogen species (IC50 = 29.10 μg/mL for O2•−, IC50 = 1.87 μg/mL for HOCl and IC50 = 1.18 μg/mL for •NO). The phenolic profile showed the presence of caffeoylquinic acids, proanthocyanidin, and quercetin in all samples. However, caffeoylquinic acids and quercetin were detected in higher amounts in the alcoholic extract, while proanthocyanidins were prevalent in the hydroalcoholic extract. No adverse effects were observed on Caco-2 viability, while the highest concentration (1000 µg/mL) of hydroalcoholic and alcoholic extracts conducted to a decrease of HT29-MTX viability. These results highlight the MAE potentialities to extract bioactive compounds from kiwiberry leaf. 相似文献
108.
Masudulla Khan Azhar U. Khan Nina Bogdanchikova Diana Garibo 《Molecules (Basel, Switzerland)》2021,26(9)
The possibility of using silver nanoparticles (AgNPs) to enhance the plants growth, crop production, and control of plant diseases is currently being researched. One of the most effective approaches for the production of AgNPs is green synthesis. Herein, we report a green and phytogenic synthesis of AgNPs by using aqueous extract of strawberry waste (solid waste after fruit juice extraction) as a novel bioresource, which is a non-hazardous and inexpensive that can act as a reducing, capping, and stabilizing agent. Successful biosynthesis of AgNPs was monitored by UV-visible spectroscopy showing a surface plasmon resonance (SPR) peak at ~415 nm. The X-ray diffraction studies confirm the face-centered cubic crystalline AgNPs. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques confirm the rectangular shape with an average size of ~55 nm. The antibacterial and antifungal efficacy and inhibitory impact of the biosynthesized AgNPs were tested against nematode, Meloidogyne incognita, plant pathogenic bacterium, Ralstonia solanacearum and fungus, Fusarium oxysporum. These results confirm that biosynthesized AgNPs can significantly control these plant pathogens. 相似文献
109.
Anna Carbone Stella Cascioferro Barbara Parrino Daniela Carbone Camilla Pecoraro Domenico Schillaci Maria Grazia Cusimano Girolamo Cirrincione Patrizia Diana 《Molecules (Basel, Switzerland)》2021,26(1)
Anti-virulence strategy is currently considered a promising approach to overcome the global threat of the antibiotic resistance. Among different bacterial virulence factors, the biofilm formation is recognized as one of the most relevant. Considering the high and growing percentage of multi-drug resistant infections that are biofilm-mediated, new therapeutic agents capable of counteracting the formation of biofilms are urgently required. In this scenario, a new series of 18 thiazole derivatives was efficiently synthesized and evaluated for its ability to inhibit biofilm formation against the Gram-positive bacterial reference strains Staphylococcus aureus ATCC 25923 and S. aureus ATCC 6538 and the Gram-negative strain Pseudomonas aeruginosa ATCC 15442. Most of the new compounds showed a marked selectivity against the Gram-positive strains. Remarkably, five compounds exhibited BIC50 values against S. aureus ATCC 25923 ranging from 1.0 to 9.1 µM. The new compounds, affecting the biofilm formation without any interference on microbial growth, can be considered promising lead compounds for the development of a new class of anti-virulence agents. 相似文献
110.
Poullet JB Sima DM Van Huffel S Van Hecke P 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,186(2):293-304
Accurate and efficient filtering techniques are required to suppress large nuisance components present in short-echo time magnetic resonance (MR) spectra. This paper discusses two powerful filtering techniques used in long-echo time MR spectral quantitation, the maximum-phase FIR filter (MP-FIR) and the Hankel-Lanczos Singular Value Decomposition with Partial ReOrthogonalization (HLSVD-PRO), and shows that they can be applied to their more complex short-echo time spectral counterparts. Both filters are validated and compared through extensive simulations. Their properties are discussed. In particular, the capability of MP-FIR for dealing with macromolecular components is emphasized. Although this property does not make a large difference for long-echo time MR spectra, it can be important when quantifying short-echo time spectra. 相似文献