scholarly journals An Active Surface Preservation Strategy for the Rational Development of Carbon Dots as pH-Responsive Fluorescent Nanosensors

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 191
Author(s):  
Ana Carolina P. Afonso ◽  
Ana Salomé Correia ◽  
Diana Duarte ◽  
Ana T. S. C. Brandão ◽  
Maria del Valle Martínez de Yuso ◽  
...  
Keyword(s):  
Fluorescence Enhancement ◽  
Green Emission ◽  
Active Surface ◽  
Ph Sensors ◽  
One Pot ◽  
Ph Values ◽  
Rational Development ◽  
High Concentrations ◽  
Post Synthesis ◽  
Ph Variations

Here we report the rational development of a carbon dot (CDs)-based fluorescent pH nanosensor by employing an active surface preservation strategy. More specifically, citric acid, urea and fluorescein were subjected to a one-pot hydrothermal treatment, which preserved fluorescein-like structures on the surface of the CDs. The obtained CDs showed pH-sensitive green emission, which can be used to determine pH variations from 3.7 to 12.1 by fluorescence enhancement. Moreover, the obtained nanoparticles showed excellent selectivity toward pH, fluorescence reversibility in different pH values, photostability, while being compatible with human cell lines (even at high concentrations). Furthermore, their performance as pH sensors was comparable with reference pH determination procedures. Thus, an active surface preservation strategy was successfully employed to develop fluorescence pH nanosensors in a rational manner and without post-synthesis functionalization strategies, which show potential for future use in pH determination.

scholarly journals One-Pot Synthesis of Ru-Doped ZnO Oxides for Photodegradation of 4-Chlorophenol

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Maria E. Manríquez ◽  
Luis Enrique Noreña ◽  
Jin An Wang ◽  
Lifang Chen ◽  
Jose Salmones ◽  
...  
Keyword(s):  
Band Gap ◽  
Mixed Oxides ◽  
Active Surface ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
One Pot ◽  
Notable Increase ◽  
Doped Zno ◽  
The One

The photocatalytic degradation of 4-chlorophenol in water using Ru-doped ZnO mixed oxides (0, 0.5, 1, and 3 wt% RuO2) synthesized by the one-pot homogeneous coprecipitation method is reported. ZnO with wurtzite structure was present in the mixed oxide as corroborated by Raman spectroscopy and X-ray diffraction analysis. All the samples showed nanorod morphological features. The presence of Ru6+/Ru4+ couples on ZnO modified the band gap of the mixed oxides and led to a shift of the band gap energy from 3.20 eV to 3.07 eV. Ru addition increased the surface area and significantly promoted the formation of active surface oxygen species such as hydroradicals evidenced by the fluorescence spectroscopy measurement. In the photodegradation of 4-chlorophenol solution under UV irradiation, a notable increase in photoactivity was obtained as the amount of RuO2 in the mixed oxides increased to 3 wt%. The charge transfer between Ru6+/Ru4+ couples and ZnO nanoparticles together with the formation of free radical oxidant species effectively inhibits electron-hole recombination rate, thus favoring the photodegradation of 4-chlorophenol.

One-pot development of water soluble copper nanoclusters with red emission and aggregation induced fluorescence enhancement

RSC Advances ◽  
2016 ◽  
Vol 6 (41) ◽  
pp. 34090-34095 ◽  
Author(s):  
Dan Li ◽  
Zhenhua Chen ◽  
Zhanghui Wan ◽  
Tiezhu Yang ◽  
Hao Wang ◽  
...  
Keyword(s):  
Fluorescence Enhancement ◽  
Water Soluble ◽  
Copper Nanoclusters ◽  
One Pot ◽  
Red Emission

The binding of Zn2+ and Al3+ to OH on the copper core of Cu NCs promotes the formation of Cu NC–OH–Zn–OH–Cu NCs and Cu NC–OH–Al–OH–Cu NCs aggregates, which enables aggregation induced fluorescence enhancement.

Preliminary Study on the Removal of Hexavalent Chromium in Wastewater with Reduction of Sulfur Dioxide

2013 ◽  
Vol 864-867 ◽  
pp. 1699-1703
Author(s):  
Ji Ming Wu ◽  
Sheng Gao Cheng
Keyword(s):  
Reaction Time ◽  
Sulfur Dioxide ◽  
Hexavalent Chromium ◽  
Reduction Reaction ◽  
High Concentration ◽  
Reaction Conditions ◽  
Ph Values ◽  
Different Temperatures ◽  
Preliminary Study ◽  
High Concentrations

The paper focused on a self-developed methodology through using sulfur dioxide to deal with high concentration of chromium-containing wastewater. It studied the effects of different pH values, different reaction time, different temperatures and different amounts of sulfur with sulfur dioxide reduction reaction on the chromium-containing wastewater. The results showed that: when the reaction conditions were controlled as follows: the pH values ranged from 2 to 4, the reaction temperature was controlled 40~60°C, the amount of sulfur in theoretical was 1.2 times and the reaction time was 40 min, the hexavalent chromium in the high concentrations of chromium-containing wastewater could be effectively removed.

scholarly journals Rapid Biodegradation of the Organophosphorus Insecticide Chlorpyrifos by Cupriavidus nantongensis X1T

2019 ◽  
Vol 16 (23) ◽  
pp. 4593 ◽  
Author(s):  
Shi ◽  
Fang ◽  
Qin ◽  
Chen ◽  
Wu ◽  
...  
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Aquatic Organisms ◽  
Organophosphorus Hydrolase ◽  
Organophosphorus Insecticides ◽  
Ph Values ◽  
Qpcr Analysis ◽  
Wide Range ◽  
Degradation Activity ◽  
High Concentrations

Chlorpyrifos was one of the most widely used organophosphorus insecticides and the neurotoxicity and genotoxicity of chlorpyrifos to mammals, aquatic organisms and other non-target organisms have caused much public concern. Cupriavidus nantongensis X1T, a type of strain of the genus Cupriavidus, is capable of efficiently degrading 200 mg/L of chlorpyrifos within 48 h. This is ~100 fold faster than Enterobacter B-14, a well-studied chlorpyrifos-degrading bacterial strain. Strain X1T can tolerate high concentrations (500 mg/L) of chlorpyrifos over a wide range of temperatures (30–42 °C) and pH values (5–9). RT-qPCR analysis showed that the organophosphorus hydrolase (OpdB) in strain X1T was an inducible enzyme, and the crude enzyme isolated in vitro could still maintain 75% degradation activity. Strain X1T can simultaneously degrade chlorpyrifos and its main hydrolysate 3,5,6-trichloro-2-pyridinol. TCP could be further metabolized through stepwise oxidative dechlorination and further opening of the benzene ring to be completely degraded by the tricarboxylic acid cycle. The results provide a potential means for the remediation of chlorpyrifos- contaminated soil and water.

Facile one-pot synthesis of highly monodisperse nickel microspheres with raised nickel dots and their adsorption performance for heavy metal ions

2016 ◽  
Vol 45 (23) ◽  
pp. 9704-9711 ◽  
Author(s):  
Yue Teng ◽  
Le Xin Song ◽  
Wei Liu ◽  
Li Zhao ◽  
Juan Xia ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Solvothermal Synthesis ◽  
Heavy Metal Ions ◽  
One Pot ◽  
Adsorption Performance ◽  
One Pot Synthesis ◽  
High Concentrations

Monodispersed Ni microspheres with surfaces uniformly covered by Ni dots were constructed through a facile solvothermal synthesis, showing an improved ability to remove Cd2+ ions even at high concentrations in water.

The Influence of Different Ph Values and High Concentrations of Na2SO4 and NaCl on the Photocatalytic Oxidation (PCO) of Methylene Blue (MB) by Aqueous Suspension of Nano-Sized TiO2

2012 ◽  
Vol 490-495 ◽  
pp. 3892-3896
Author(s):  
Yu Ping Jiang
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Oxidation ◽  
High Salinity ◽  
Aqueous Suspension ◽  
Ion Concentration ◽  
Ph Values ◽  
Orthogonal Experiments ◽  
Degradation Rates ◽  
The Difference ◽  
High Concentrations

To study the PCO of high-salinity organic wastewater, nano-sized TiO2 was used for PCO of MB in solutions with different pH values and high concentrations of Na2SO4 or NaCl. The rates of PCO were monitored by total organic carbon (TOC) measurement. The results showed that the degradation rates increased with increasing pH and decreased as the concentration of Na2SO4 or NaCl increased. The difference of degradation rates in Na2SO4 or NaCl aqueous solutions increased as the ion concentration increased. In the orthogonal experiments, the rates decreased remarkably under certain ratios of the ions concentration. The mechanisms were explored in some detail.

scholarly journals Amino acid transport by resealed ghosts from pigeon erythrocytes

1982 ◽  
Vol 202 (3) ◽  
pp. 613-621
Author(s):  
K P Wheeler
Keyword(s):  
Amino Acids ◽  
Concentration Gradient ◽  
Acid Transport ◽  
Ph Values ◽  
Intracellular Amino Acids ◽  
Net Flux ◽  
High Concentrations ◽  
Dependent Transport ◽  
Resealed Ghosts ◽  
Net Fluxes

Resealed ghosts from pigeon erythrocytes were shown to haemolyse during incubation in isotonic media with pH values greater than about 7 and high concentrations of Na+ inside the ghosts seemed to enhance this effect. At lower pH values the ghosts were stable but still highly permeable to Na+ and K+, and moderately permeable to sucrose. Under the latter conditions the ghosts transported amino acids in a way qualitatively but not quantitatively similar to intact erythrocytes. The Na+-dependent transport of serine and alanine by the ghosts consisted essentially of an exchange of extracellular for intracellular amino acids, with no significant net flux. In contrast, net fluxes of glycine in the direction of the Na+-concentration gradient across the ghost membrane were demonstrated. However, under one condition a small net influx of glycine occurred against the prevailing Na+-concentration gradient. Unlike Na+-dependent glycine uptake, the uptake of six other amino acids by intact pigeon erythrocytes was not influenced by the nature of the anion present. The significance of these findings in relation to previous work on the Na+-gradient hypothesis of membrane transport is discussed.

scholarly journals Evaluación de la degradación de superficies de fluorapatita mediante técnicas electroquímicas. (Degradation Assessment of Fluorapatite Surfaces using Electrochemical Techniques)

2015 ◽  
Vol 6 (1) ◽  
pp. 33 ◽  
Author(s):  
L. J. Reyes Jaimes ◽  
H. A. González Romero ◽  
A. Sandoval Amadora ◽  
D. Y. Peña Ballesteros ◽  
H. A. Estupiñán Durán
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Immersion Time ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Active Surface ◽  
Apatite Formation ◽  
X Ray ◽  
Cathodic Electrodeposition ◽  
High Concentrations

ResumenSe evaluó el efecto del pH de fluido corporal simulado en la formación de apatitas y en la degradación de superficies de la aleación Ti6Al4V recubiertas con Fosfato de Calcio mediante la técnica de lectrodeposición catódica. Como variables de estudio se tomaron el pH del fluido corporal simulado y el tiempo de inmersión de los recubrimientos. Mediante microscopia electrónica de barrido, espectroscopia de energía dispersiva, difracción de rayos X y absorción atómica se pudo corroborar la formación de apatitas, y la degradación de los recubrimientos se evaluó mediante Espectroscopia de impedancia electroquímica y curvas de polarización potenciodinámicas. Los resultados obtenidos muestran que los recubrimientos tenían altas concentraciones de Fluorapatita (Ca5(PO4)3F) y que su formación se ve favorecida a medida que el pH del fluido corporal simulado y el tiempo de inmersión aumenta. Por otra parte, se obtuvo que las muestras evaluadas a pH de 7,2 son menos estables termodinámicamente, sin embargo, las evaluadas a 7,6 presentan una superficie más activa, por lo que se obtiene una mayor velocidad de degradación. AbstractThe pH eect of a Simulated Body Fluid in the apatite formation and the degradation of the Ti6Al4V alloy surfaces, coated by calcium phosphate obtained through cathodic electrodeposition was evaluated. The simulated body fluid pH and the coating immersion time were taken as variables. The formation of apatite was corroborated by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X Ray Diraction and Atomic Absorption Techniques. The coating degradation was assessed by the Electrochemical Impedance Spectroscopy and the Potential Dynamic Polarization Curves. The results have shown that the coatings had high concentrations of fluorapatite (Ca5(PO4)3F) and its formation was favored as the simulated body fluid pH and the immersion time increases. Moreover, it was found that the coatings samples evaluated at pH 7.2 were less thermodynamically steady, however, the evaluated coating at pH 7.6 exhibited a more active surface, so that a higher rate of degradation is obtained.

scholarly journals Biochar-Assisted Phytostabilization for Potentially Toxic Element Immobilization

2021 ◽  
Vol 14 (1) ◽  
pp. 445
Author(s):  
Maja Radziemska ◽  
Zygmunt Mariusz Gusiatin ◽  
Zbigniew Mazur ◽  
Tereza Hammerschmiedt ◽  
Agnieszka Bęś ◽  
...  
Keyword(s):  
New Technologies ◽  
Plant Biomass ◽  
Dactylis Glomerata ◽  
Total Content ◽  
Absorption Spectrometry ◽  
New Approach ◽  
Ph Values ◽  
High Concentrations ◽  
Dactylis Glomerata L

In response to the growing threat to the quality of the soil environment, new technologies are being developed to protect and remediate contaminated sites. A new approach, namely, assisted phytostabilization, has been used in areas contaminated with high levels of potentially toxic elements (PTEs), using various soil additives. This paper determined the effectiveness of biochar-assisted phytostabilization using Dactylis glomerata L. of soil contaminated with high concentrations of the selected PTEs (in mg/kg soil): Cu (780 ± 144), Cd (25.9 ± 2.5), Pb (13,540 ± 669) and Zn (8433 ± 1376). The content of the selected PTEs in the roots and above-ground parts of the tested grass, and in the soil, was determined by atomic absorption spectrometry (AAS). The addition of biochar to the contaminated soil led to an increase in plant biomass and caused an increase in soil pH values. Concentrations of Cu, Cd, Pb and Zn were higher in the roots than in the above-ground parts of Dactylis glomerata L. The application of biochar significantly reduced the total content of PTEs in the soil after finishing the phytostabilization experiment, as well as reducing the content of bioavailable forms extracted from the soil using CaCl2 solution, which was clearly visible with respect to Cd and Pb. It is concluded that the use of biochar in supporting the processes of assisted phytostabilization of soils contaminated with PTEs is justified.

Facile Preparation of a Surface-Enriched Pt Layer Over Pd/C as an Efficient Oxygen Reduction Catalyst With Enhanced Activity and Stability

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
Narayanamoorthy Bhuvanendran ◽  
Sabarinathan Ravichandran ◽  
Qian Xu ◽  
Sivakumar Pasupathi ◽  
Huaneng Su
Keyword(s):  
Surface Layer ◽  
Oxygen Reduction ◽  
Structural Characteristics ◽  
Active Surface ◽  
Reduction Reaction ◽  
Intrinsic Activity ◽  
Active Surface Area ◽  
One Pot ◽  
Electrocatalytic Performance ◽  
Improved Stability

Abstract Pt-enriched surface layer formation on Vulcan carbon-supported Pd (Pt@Pd/C) was successfully prepared through a simple and one-pot formic acid reduction approach without any stabilizing agent. The electrocatalytic performance of Pt@Pd/C catalyst toward an oxygen reduction reaction (ORR) in alkaline medium was studied and also compared with standard carbon-supported Pt (Pt/C) and Pd (Pd/C) catalysts. The Pt@Pd/C exhibits higher electrochemical active surface area (74.7 m2/g) and mass activity (1.38 mA/µg) than Pt/C, Pd/C, and contending with standard reported catalysts. In durability tests, Pt@Pd/C showed negligible loss of intrinsic activity (∼10%) after 10,000 cycles which confirmed improved stability than Pt-based catalysts for ORR in KOH medium. This improved electrocatalytic performance could be attributed to their structural characteristics of the Pt-enriched surface layer on Pd/C-core and the compressive lattice strain on Pt. The present investigation demonstrates the simple preparation procedure for surface-enriched Pt on Pd/C and its improved performance for ORR, suggesting that it is a promising contender to benchmark ORR catalysts for alkaline fuel cells.

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