A general, Brønsted acid catalyzed method for the room temperature, nucleophilic ring opening of donor–acceptor cyclopropanes in fluorinated alcohol solvent, HFIP, is described. Salient features of ...this method include an expanded cyclopropane scope, including those bearing single keto-acceptor groups and those bearing electron-deficient aryl groups. Notably, the catalytic system proved amenable to a wide range of nucleophiles including arenes, indoles, azides, diketones, and alcohols.
Highly electronically deactivated benzylic alcohols, including those with a CF3 group adjacent to the OH‐bearing carbon, undergo dehydrative Friedel–Crafts reactions upon exposure to catalytic ...Brønsted acid in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) solvent. Titration and kinetic experiments support the involvement of higher order solvent/acid clusters in catalysis.
More than a solvent: The use of the fluorinated solvent 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) and a catalytic amount of a strong Brønsted acid enables dehydrative Friedel–Crafts reactions of highly deactivated benzylic alcohols. Mixed aggregates of acid and HFIP are likely to be involved in the catalysis.
► The sorption of Pb
2+ on oxidized and amino-functionalized MWCNTs follow the Langmuir sorption isotherm. ► Pb
2+ adsorption by MWCNTs is dependent on the number of amino groups in alkyl chains, pH ...and temperature. ► The sorption of Pb
2+ on MWCNTs is a rather complex and spontaneous process. ► Mechanism of sorption includes both physisorption and chemisorption mechanisms. ► MWCNTs can be reused over five times with minimal loss of adsorption capacity.
Pristine, oxidized, ethylenediamine, diethylenetriamine and triethylenetetramine modified multi-walled carbon nanotubes (raw-MWCNT, o-MWCNT, e-MWCNT, d-MWCNT and t-MWCNT, respectively) were employed as adsorbents in order to study individual and competitive adsorption characteristics of Pb
2+ and Cd
2+ ions. In batch tests, the influence of functionalization, pH, contact time, initial metal ion concentration and temperature, on the ion adsorption on MWCNTs was studied. Adsorption of Pb
2+ and Cd
2+ on MWCNTs strongly depends on pH. Time dependent Pb
2+ adsorption and adsorption data can be described by pseudo-second-order kinetic model and by Langmuir isotherm, respectively. The maximum adsorption capacities of Pb
2+ and Cd
2+ on d-MWCNT were 58.26 and 31.45
mg
g
−1 at 45
°C, respectively. The competitive adsorption studies showed that the metal order affinity with respect to d-MWCNT and e-MWCNT is Pb
2+
>
Cd
2+. Thermodynamic parameters showed that the adsorption of Pb
2+ on appropriate nanotubes was spontaneous and endothermic. According to desorption studies, regenerated MWCNT can be reused over five times with minimal loss of adsorption capacity. Comparison of obtained results with capacities and affinities of other adsorbents indicates suitability of amino-functionalized MWCNT application for removal of Pb
2+ and Cd
2+ from aqueous solution.
High temperatures have significant impacts on fruit tree production. Foliar spraying application of promoting agents can be a sustainable approach to managing high-temperature stress in orchards. The ...mechanism of certain improving agents on photosynthesis is not yet well understood, particularly in fruit trees. Photosynthesis, as a vital and very sensitive process in plants, is a pivotal component in fruit production. Therefore, in this study, we explored the potential of two different promoting agents, salicylic acid (SA) and ascorbic acid (AsA), to alleviate oxidative stress caused by high temperature in controlled conditions (37°C for 1 h) at the photosynthetic level. For studying photosynthetic responses, we used chlorophyll fluorescence measurements. According to our findings, foliar application of promoting agents effectively increased the high-temperature tolerance of apple leaves, when compared to sole heat stress treatment. Both promoting agents significantly increased photosynthetic efficiency under stress, while the maximum was observed with AsA. In general, AsA and SA applications had a positive effect on the photosynthesis of apple leaves at high temperatures.
While changes in nuclear structure and organization are frequently observed in cancer cells, relatively little is known about how nuclear architecture impacts cancer progression and pathology. To ...begin to address this question, we studied Nuclear Transport Factor 2 (NTF2) because its levels decrease during melanoma progression. We show that increasing NTF2 expression in WM983B metastatic melanoma cells reduces cell proliferation and motility while increasing apoptosis. We also demonstrate that increasing NTF2 expression in these cells significantly inhibits metastasis and prolongs survival of mice. NTF2 levels affect the expression and nuclear positioning of a number of genes associated with cell proliferation and migration, and increasing NTF2 expression leads to changes in nuclear size, nuclear lamin A levels, and chromatin organization. Thus, ectopic expression of NTF2 in WM983B metastatic melanoma abrogates phenotypes associated with advanced stage cancer both in vitro and in vivo, concomitantly altering nuclear and chromatin structure and generating a gene expression profile with characteristics of primary melanoma. We propose that NTF2 is a melanoma tumor suppressor and could be a novel therapeutic target to improve health outcomes of melanoma patients.
In this study, the JIP test was used to assess the drought tolerance of two sweet cherry cultivars (Prunus avium L.) (modern and autochthonous). Plants were exposed to progressive drought by ...withholding water and their fast (< 1 s) chlorophyll fluorescence kinetics was evaluated. JIP test analysis showed that drought stress caused a greater decrease in performance indices (PIABS and PItotal) in a modern cultivar, as compared to an autochthonous one. Our results suggest that limited reoxidation of primary quinone electron acceptor (QA), higher amount of secondary quinone electron acceptor (QB-) nonreducing reaction centres, or inhibition of the electron transport between QA and QB, decreased more seriously the photosynthetic performance of the modern cultivar. Further, higher positive L- and K-bands observed for the modern cultivar also suggest lower energetic connectivity between PSII units and increased inhibition of oxygen-evolving complex over autochthonous cultivar. Our results suggest that the autochthonous cultivar Crveni hrušt had better photosynthetic performance under drought conditions, compared to the modern cultivar New Star.
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► Iron(III)-oxide loaded e-MWCNT shows good sorption affinity for arsenic(V). ► The sorption pattern of As(V) fits well to the Freundlich model. ► As(V) adsorption is dependent to ...iron(III)-oxide content, pH and temperature. ► The sorption of As(V) and As(III) is a rather complex and spontaneous process. ► Creation of inner-sphere surface complexes are main sorption mechanisms.
New criteria in assessing the quality of drinking water reduced the maximum permissible concentration of arsenic from 50μgL−1 to 10μgL−1, and set a requirement for the development of new technologies for arsenic removal. In this paper, ethylenediamine functionalized multiwall carbon nanotubes (e-MWCNT) were loaded with iron(III) oxide in the goethite form, by precipitation of adsorbed Fe3+ and oxidized Fe2+ using base, in that way e-MWCNT/Fe3+ and e-MWCNT/Fe2+ adsorbents, respectively, were obtained. The influence of pH on the As(V) and As(III) removal from drinking water was studied in a batch system, of pH range 3–10 and initial arsenic concentration 0.05–4mgL−1. Time dependent As(V) adsorption and adsorption data can be described by pseudo-second-order kinetic model and by Freundlich isotherm, applying linear and non-linear fitting methods. The maximum adsorption capacities obtained from Langmuir model for As(V) on e-MWCNT/Fe2+ and e-MWCNT/Fe3+ were 23.47 and 13.74mgg−1 at 25°C, respectively. Thermodynamic parameters showed that the adsorption of As(V) was spontaneous and endothermic for both e-MWCNT/Fe2+ and e-MWCNT/Fe3+. Influences of the pH, iron(III) oxide loading and interfering ions were modeled by MINTEQ program, and good agreement between experimental and modeling data was obtained.
Altered nuclear size is associated with many cancers, and determining whether cancer-associated changes in nuclear size contribute to carcinogenesis necessitates an understanding of mechanisms of ...nuclear size regulation. Although nuclear import rates generally positively correlate with nuclear size, NTF2 levels negatively affect nuclear size, despite the role of NTF2 (also known as NUTF2) in nuclear recycling of the import factor Ran. We show that binding of Ran to NTF2 is required for NTF2 to inhibit nuclear expansion and import of large cargo molecules in Xenopus laevis egg and embryo extracts, consistent with our observation that NTF2 reduces the diameter of the nuclear pore complex (NPC) in a Ran-binding-dependent manner. Furthermore, we demonstrate that ectopic NTF2 expression in Xenopus embryos and mammalian tissue culture cells alters nuclear size. Finally, we show that increases in nuclear size during melanoma progression correlate with reduced NTF2 expression, and increasing NTF2 levels in melanoma cells is sufficient to reduce nuclear size. These results show a conserved capacity for NTF2 to impact on nuclear size, and we propose that NTF2 might be a new cancer biomarker.
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