There are tens of millions of contaminated soil sites in the world, and with an increasing population and associated risk there is a growing pressure to remediate them. A barrier to remediation is ...the lack of cost-effective approaches to assessment. Soil contaminants include a wide range of natural and synthetic metallic and organic compounds and minerals thus making analytical costs potentially very large. Further, soil contaminants show a large degree of spatial variation which increases the burden on sampling costs. This paper reviews potentially cost-effective methods for measurement, sampling design, and assessment. Current tiered investigation approaches and sampling strategies can be improved by using new technologies such as proximal sensing. Design of sampling can be aided by on-the-go proximal soil sensing; and expedited by subsequent adaptive spatially optimal sampling and prediction procedures enabled by field spectroscopic methods and advanced geostatistics. Field deployment of portable Visible & Near Infrared wavelength 400–2500nm (Vis-NIR) and X-ray fluorescence (PXRF) spectroscopies will require special calibration approaches but show huge potential for synergistic use. The use of mid-infrared spectroscopy wavelength 2500–25,000nm, wavenumber 4000–400cm−1 (MIR) for field implementation requires further adaptive research. We propose an integrated field-deployable methodology as a basis for further developments.
•There is still a large number of contaminated soil sites worldwide.•Lab analysis of soil contaminants increases investigation and remediation costs.•Field-deployable portable instruments for Vis-NIR and PXRF are now widely available.•A new approach includes adaptive sampling supported by on-the-go Vis-NIR and PXRF.
This work investigates the use of a silver-based metal–organic framework (MOF) for mitigating biofouling in forward-osmosis thin-film composite (TFC) membranes. This is the first study of the use of ...MOFs for biofouling control in membranes. MOF nanocrystals were immobilized in the active layer of the membranes via dispersion in the organic solution used for interfacial polymerization. Field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) characterization results showed the presence of the MOF nanocrystals in the active layer of the membranes. The immobilization improved the membrane active layer in terms of hydrophilicity and transport properties without adversely affecting the selectivity. It imparted antibacterial activity to the membranes; the number of live bacteria attached to the membrane surface was over 90% less than that of control membranes. Additionally, the MOF nanocrystals provided biocidal activity that lasted for 6 months. The immobilization improved biofouling resistance in the membranes, whose flux had a decline of 8% after 24 h of operation in biofouling experiments, while that of the control membranes had a greater decline of ∼21%. The better biofouling resistance is due to simultaneous improvement of antiadhesive and antimicrobial properties of the membranes. Fluorescence microscopy and FE-SEM indicated simultaneous improvement in antiadhesive and antimicrobial properties of the TFN membranes, resulting in limited biofilm formation.
Green, economical and effective method was developed for synthesis of fluorescent carbon dots (CDs), using one-pot hydrothermal treatment of Lycii Fructus. Optical and structural properties of the ...CDs have been extensively studied by UV–visible and fluorescence spectroscopic, x-ray diffraction (XRD) techniques, transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Surface functionality and composition of CDs has been illustrated by Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) spectra and elemental analysis. The fabricated CDs possess stable fluorescent properties. The fluorescent quantum yield of the CDs can reach 17.2%. The prepared CDs emitted a broad fluorescence between 415 and 545nm and their fluorescence was tuned by changing excitation wavelength. Meanwhile, the fluorescence intensity of the CDs could be significantly quenched by Fe3+ (turn-off). The CDs exhibit captivating sensitivity and selectivity toward Fe3+ with a linear range from 0 to 30μM and a detection limit of 21nM. The prepared CDs were successfully applied to the determination of Fe3+ in the urine samples, the water samples from the from the Yellow River and living HeLa (Henrietta Lacks) cells. Moreover, the low-toxicity and excellent biocompatibility of the CDs were evaluated through MTT assay on HeLa cells. The CDs were also employed as fluorescent probes for multicolor imaging of HeLa cells successfully.
•A green, simple, eco-friendly strategy for synthesizing carbon dots (CDs) were established.•The CDs were explored for fluorescent detection of Fe3+ with high sensitivity and selectivity.•The CDs were successfully applied for multicolor cell imaging.
•The main analytical tools for characterization of drug–cyclodextrin complexes in the solid state are reviewed.•The potential advantages, drawbacks and limits of each method are discussed.•The ...applicability of each method is discussed and illustrated by specific examples from literature.
Cyclodextrins are cyclic oligosaccharides able to form inclusion complexes with a variety of hydrophobic guest molecules, positively modifying their physicochemical properties. A thorough analytical characterization of cyclodextrin complexes is of fundamental importance to provide an adequate support in selection of the most suitable cyclodextrin for each guest molecule, and also in view of possible future patenting and marketing of drug–cyclodextrin formulations. The demonstration of the actual formation of a drug–cyclodextrin inclusion complex in solution does not guarantee its existence also in the solid state. Moreover, the technique used to prepare the solid complex can strongly influence the properties of the final product. Therefore, an appropriate characterization of the drug–cyclodextrin solid systems obtained has also a key role in driving in the choice of the most effective preparation method, able to maximize host–guest interactions. The analytical characterization of drug–cyclodextrin solid systems and the assessment of the actual inclusion complex formation is not a simple task and involves the combined use of several analytical techniques, whose results have to be evaluated together.
The objective of the present review is to present a general prospect of the principal analytical techniques which can be employed for a suitable characterization of drug–cyclodextrin systems in the solid state, evidencing their respective potential advantages and limits. The applications of each examined technique are described and discussed by pertinent examples from literature.
The synthesis of a Co metal-organic framework assembled from 5,10,15,20-tetrakis((pyridin-4-yl)phenyl)porphyrin; TPhPyP) "Co-MTPhPyP" is reported. The TPhPyP ligand was synthesized via aldehyde ...condensation in 28% yield and characterized by
H nuclear magnetic resonance (
H NMR), Fourier-transform infrared (FTIR), high-resolution mass spectrometry (HRMS), and UV-visible spectroscopy (UV-vis). Co-MTPhPyP was prepared by the solvothermal method from TPhPyP and CoCl
·H
O in 55% yield and characterized by X-ray powder diffraction (XRD), FTIR, thermogravimetric analysis (TGA), field-emission scanning electron microscopy with energy-dispersive X-ray (FESEM-EDS), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS), showing a particle size distribution of 418 ± 58 nm. The sorption properties of the Co-MTPhPyP for the effective removal of Pb(II) and Cu(II) were evaluated in an aqueous medium and Cthe results showed uptake capacities of 383.4 and 168 mg of the metal g
after 2 h, respectively. Kinetic studies of Pb(II) adsorption by Co-MTPhPyP were adjusted to the pseudo-second-order model with a maximum adsorption capacity of 458.8 mg g
at 30 min of exposition.
Electrochemically grown cobalt on graphene exhibits exceptional performance as a catalyst for the oxygen evolution reaction (OER) and provides the possibility of controlling the morphology and the ...chemical properties during deposition. However, the detailed atomic structure of this hybrid material is not well understood. To elucidate the Co/graphene electronic structure, we have developed a flow cell closed by a graphene membrane that provides electronic and chemical information on the active surfaces under atmospheric pressure and in the presence of liquids by means of X‐ray photoelectron spectroscopy (XPS). We found that cobalt is anchored on graphene via carbonyl‐like species, namely Co(CO)x, promoting the reduction of Co3+ to Co2+, which is believed to be the active site of the catalyst.
The electronic structure of cobalt on graphene was investigated with a new flow cell that provides electronic and chemical information on the active surfaces by means of X‐ray photoelectron spectroscopy. It is shown that cobalt is anchored on graphene via carbonyl‐like species, promoting the reduction of Co3+ to Co2+, which is believed to be the active site of the catalyst.
Semiconductor heterojunctions are used in a wide range of applications including catalysis, sensors, and solar‐to‐chemical energy conversion devices. These materials can spatially separate ...photogenerated charge across the heterojunction boundary, inhibiting recombination processes and synergistically enhancing their performance beyond the individual components. In this work, the WO3/TiO2 heterojunction grown by chemical vapor deposition is investigated. This consists of a highly nanostructured WO3 layer of vertically aligned nanorods that is then coated with a conformal layer of TiO2. This heterojunction shows an unusual electron transfer process, where photogenerated electrons move from the WO3 layer into TiO2. State‐of‐the‐art hybrid density functional theory and hard X‐ray photoelectron spectroscopy are used to elucidate the electronic interaction at the WO3/TiO2 interface. Transient absorption spectroscopy shows that recombination is substantially reduced, extending both the lifetime and population of photogenerated charges into timescales relevant to most photocatalytic processes. This increases the photocatalytic efficiency of the material, which is among the highest ever reported for a thin film. In allying computational and experimental methods, this is believed to be an ideal strategy for determining the band alignment in metal oxide heterojunction systems.
Advanced nanostructured WO3/TiO2 heterojunction films are deposited using chemical vapor deposition methods. Against common observation, this system shows an unusual electron transfer from WO3 to TiO2, as proven by theoretical and experimental standpoints. The advantageous electronic synergy within a high‐surface‐area substrate promotes its photocatalytic properties showing record‐high efficiencies for the degradation of organic pollutants.
Polymer electrolyte membranes based on the natural polymer κ-carrageenan were modified and characterized for application in electrochemical devices. In general, pure κ-carrageenan membranes show a ...low ionic conductivity. New membranes were developed by chemically modifying κ-carrageenan via phosphorylation to produce O-methylene phosphonic κ-carrageenan (OMPC), which showed enhanced membrane conductivity. The membranes were prepared by a solution casting method. The chemical structure of OMPC samples were characterized using Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) spectroscopy and 31P nuclear magnetic resonance (31P NMR) spectroscopy. The conductivity properties of the membranes were investigated by electrochemical impedance spectroscopy (EIS). The characterization demonstrated that the membranes had been successfully produced. The ionic conductivity of κ-carrageenan and OMPC were 2.79 × 10-6 S cm-1 and 1.54 × 10-5 S cm-1, respectively. The hydrated membranes showed a two orders of magnitude higher ionic conductivity than the dried membranes.
Herein we report a rapid low cost one step green synthetic method using Actinidia deliciosa fruit extract for preparation of stable and multifunctional silver and gold nanoparticles. The synthesized ...nanoparticles were successfully used as green catalysts for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB). The enhanced biological activity of the prepared nanoparticles was investigated based on its highly stable antioxidant, anticancer and bactericidal effects. TEM micrographs showed that the silver nanoparticles (AgNPs) formed were predominantly spherical in shape having diameters ranging from 25 to 40nm, while gold nanoparticles (AuNPs) shown particle size ranges from 7 to 20nm. EDAX (energy-dispersive X-ray spectroscopy) and XPS (X-ray photoelectron spectroscopy) results confirmed the presence of elemental silver and gold. X-ray diffraction (XRD) pattern revealed the formation of face-centered cubic structure for AgNPs and AuNPs. The Fourier-transform infrared (FTIR) spectrum indicated the presence of possible functional groups in the biomolecule responsible for capping the nanoparticles. The AgNPs treated HCT116 cells showed 78% viability at highest concentration (350μg/mL), while AuNPs showed 71% viability at highest concentration (350μg/mL) using MTT assay, which provides promising approach for alternative nano-drug development. The antimicrobial activity of the nanoparticles was investigated using Pseudomonas aeruginosa (P.aeruginosa) in which damaging the cell membrane was observed by TEM images. Our results revealed that the green synthesis method is easy, rapid, inexpensive, eco-friendly and efficient in developing multifunctional nanoparticles in near future in the field of biomedicine, water treatment and nanobiotechnology.
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•The method of synthesis is rapid, eco-friendly and uses naturally available fruit extract as reducing and stabilizing agent.•The synthesized nanoparticles showed good anticancer activity against HCT116 cell lines.•They have also shown excellent catalytic activity for the reduction of 4-nitrophenol and methyelene blue.•The synthesized nanoparticles have exhibited good antioxidant activity
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