Chromatography with a two-dimensional column

Summary A chromatographic method using a flat, square column developed along one direction and then eluted along the perpendicular direction, using a second retention mechanism widely different from the first one is described. Such a method would offer a potential peak capacity of several thousands, at least ten times more than either conventional column chromatography or two-dimensional thin-layer chromatography. Equipment capable of satisfying the requirements derived from a theoretical study of the operation of a two-dimensional column is also described. Results are satisfactory.Presented at the 14th International Symposium on Chromatography London, September, 1982 as a plenary lecture.     

Synthesis of silver nanoparticles via green method using ultrasound irradiation in seaweed <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> media

Green methods are a safer alternative to natural chemical and physical methods for the synthesis of silver nanoparticles (Ag-NPs), due to their being environmentally friendly and cost effective. This study offers a new green approach using ultrasound irradiation as the reducing agent and seaweed Kappaphycus alvarezii (K. alvarezii) as the natural bio-media. The seaweed K. alvarezii/Ag-NPs was characterised by ultraviolet–visible (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope with energy dispersive X-ray (FESEM-EDX), zeta potential, and Fourier transform infrared (FTIR) studies. UV–vis shows that surface plasmon resonance (SPR) arises from this solution due to the combined oscillations from the nanoparticles. The XRD study indicates the crystalline nature of the Ag-NPs. From the TEM images, the Ag-NPs are almost spherical with an average diameter of 11.78 nm. The FTIR spectrum provides adequate evidence of phytochemicals stabilising the nanoparticles. Synthesised Ag-NPs were successfully obtained using this green method.     

Self‐Construction from 2D to 3D: One‐Pot Layer‐by‐Layer Assembly of Graphene Oxide Sheets Held Together by Coordination Polymers

Deposition of Ni‐based cyanide bridged coordination polymer (NiCNNi) flakes onto the surfaces of graphene oxide (GO) sheets, which allows precise control of the resulting lamellar nanoarchitecture by in situ crystallization, is reported. GO sheets are utilized as nucleation sites that promote the optimized crystal growth of NiCNNi flakes. The NiCNNi‐coated GO sheets then self‐assemble and are stabilized as ordered lamellar nanomaterials. Regulated thermal treatment under nitrogen results in a Ni₃C–GO composite with a similar morphology to the starting material, and the Ni₃C–GO composite exhibits outstanding electrocatalytic activity and excellent durability for the oxygen reduction reaction.     

XPS and material properties of raw and oxidized carbide-derived carbon and their application in antifreeze thermal fluids/nanofluids

Journal of Thermal Analysis and Calorimetry - In this study, the stability, thermal conductivity and viscosity of carbide-derived carbon antifreeze thermal fluids were explored. The study also...     

Magnetic ZnO Crystal Nanoparticle Growth on Reduced Graphene Oxide for Enhanced Photocatalytic Performance under Visible Light Irradiation

Magnetite zinc oxide (MZ) (Fe₃O₄/ZnO) with different ratios of reduced graphene oxide (rGO) was synthesized using the solid-state method. The structural and optical properties of the nanocomposites were analyzed using transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis/DRS), and photoluminescence (PL) spectrophotometry. In particular, the analyses show higher photocatalytic movement for crystalline nanocomposite (MZG) than MZ and ZnO nanoparticles. The photocatalytic degradation of methylene blue (MB) with crystalline ZnO for 1.5 h under visible light was 12%. By contrast, the photocatalytic activity for MZG was more than 98.5%. The superior photocatalytic activity of the crystalline nanocomposite was detected to be due to the synergistic effect between magnetite and zinc oxide in the presence of reduced graphene oxide. Moreover, the fabricated nanocomposite had high electron–hole stability. The crystalline nanocomposite was stable when the material was used several times.     

INAA of ancient glass beads from Sungai Mas archaeological site,Bujang Valley,Malaysia

The multi-elemental content of sixteen glass beads and eight glass samples from archeological site Sg Mas in Bujang Valley (finding from 5 th to 14 th century) were assayed by neutron activation analysis (NAA). Ten beads differed in colour and eight of them were opaque. Contents of twentyfour elements, which might be present in the samples as a flux, stabilizer, colorants or opacifier were examined. The elements Al, Br, Cl, Co, Cr, Fe, Hf, K, Mn, Na, Sc,Th, Zn and Zr were detectable in all samples. On the other hand, concentration of the elements As, Ba, Ca, Cs, Rb, Sb, Ta, Ti, U, and V were below the detection limit in some samples. The concentration of elements found are discussed in terms of color and/or opacity of the glass bead and glass samples. Although the elemental composition does not fully explain the color and opacity of the studied materials, it can still be used as fingerprint of the glass used for the bead making.     

Genotoxicity of combined exposure to polycyclic aromatic hydrocarbons and UVA--a mechanistic study

Abstract Solar UV radiation and benzo[a]pyrene (BaP) are two carcinogenic agents. When combined, their deleterious properties are synergistic. In order to get insights into the underlying processes, we carried out a mechanistic study within isolated DNA photosensitized to UVA radiation by either BaP, its diol epoxide metabolite (BPDE) or the tetraol arising from the hydrolysis of this last molecule. Measurement of the level of the oxidized base 8-oxo-7,8-dihydroguanine revealed that BaP is a poor sensitizer while BPDE and tetraol are more potent ones. None of these compounds was found to photosensitize formation of cyclobutane pyrimidine dimers through triplet energy transfer. On the basis of the distribution of oxidized DNA bases, we could show that photosensitization of DNA by BPDE involves electron abstraction (Type I) while tetraol acts mainly through singlet oxygen production (Type II). Under our experimental conditions, Type I was the major photosensitization process, which shows the lack of involvement of tetraol in the observed photo-oxidation reaction. Finally, we could show that the adducts, resulting from the alkylation of DNA by BPDE, are very potent sensitizers. Indeed, they are located in the close vicinity of the double helix and thus perfectly placed to induce oxidation reactions.     

A Fluorogenic DNAzyme for A Thermally Stable Protein Biomarker from Fusobacterium nucleatum,a Human Bacterial Pathogen

Fusobacterium nucleatum has been correlated to many poor human conditions including oral infections, adverse pregnancies and cancer, and thus molecular tools capable of detecting this human pathogen can be used to develop diagnostic tests for them. Using a new selection method targeting thermally stable proteins without a counter-selection step, we derived an fluorogenic RNA-cleaving DNAzyme, named RFD-FN1, that can be activated by a thermally stable protein target that is unique to F. nucleatum subspecies. High thermal stability of protein targets is a very desirable attribute for DNAzyme-based biosensing directly with biological samples because nucleases found inherently in these samples can be heat-inactivated. We further demonstrate that RFD-FN1 can function as a fluorescent sensor in both human saliva and human stool samples. The discovery of RFD-FN1 paired with a highly thermal stable protein target presents opportunities for developing simpler diagnostic tests for this important pathogen.     

A Coculture Based, 3D Bioprinted Ovarian Tumor Model Combining Cancer Cells and Cancer Associated Fibroblasts

Ovarian cancer remains a major public health issue due to its poor prognosis. To develop more effective therapies, it is crucial to set-up reliable models that closely mimic the complexity of the ovarian tumor's microenvironment. 3D bioprinting is currently a promising approach to build heterogenous and reproducible cancer models with controlled shape and architecture. However, this technology is still poorly investigated to model ovarian tumors. In this study, a 3D bioprinted ovarian tumor model combining cancer cells (SKOV-3) and cancer associated fibroblasts (CAFs) are described. The resulting tumor models show their ability to maintain cell viability and proliferation. Cells are observed to self-assemble in heterotypic aggregates. Moreover, CAFs are observed to be recruited and to circle cancer cells reproducing an in vivo process taking place in the tumor microenvironment. Interestingly, this approach also shows its ability to rapidly generate a high number of reproducible tumor models that can be subjected to usual characterizations (cell viability and metabolic activity; histology and immunological studies; and real-time imaging). Therefore, these ovarian tumor models can be an interesting tool for high throughput drug screening applications.     

Comparison Between Equivalent Continuum and Discrete Crack Models of Transient Radon Transport at the Soil–Building Foundation Crack Interface Using TOUGH2/EOS7Rn

In the framework of radon risk management in France, it is necessary to enhance knowledge on radon transfer from its source to exposure areas (e.g., buildings) by developing simple, accurate, numerical models for transient radon transport in three-dimensional (3D) unsaturated porous materials. The equivalent continuum model (ECM) of flow and transport at the interface between the soil and cracks (fissures) in a building foundation (e.g., slab on grade, basement) is attractive, since equivalent (effective) continuum properties assigned to model cells can represent the combined effect of individual cracks and solid matrix of the cracked concrete of the foundation (slab and blocks walls). Although the ECM approach based on the volume averaging method has been used to model flow and transport through cracks at the soil–building interface, it has never been verified numerically. Thus, the goal of the present work is to develop an ECM using this averaging method and to quantify its uncertainties based on its comparison to an accurate numerical discrete crack model (DCM) for flow and transport in the crack. As a first step, the DCM implemented in the TOUGH2/EOS7Rn module has been verified numerically through a comparison to a reference 3D steady-state numerical solution for radon transport into a house with basement under constant negative pressure. Then, 3D results of the DCM and ECM approaches were compared, under time-dependent indoor–outdoor pressure differentials conditions, for two crack line configurations in the basement slab floor and two different soil configurations with different soil permeability and radium \(^{226}\)Ra mass content values. Results of this comparison show that, for a homogeneous soil configuration, discrepancies between ECM and DCM simulated indoor radon activity concentrations decrease with the increase in soil permeability, regardless crack line configuration in the slab floor and soil radium mass content. However, ECM uncertainties were not within the range of absolute errors on measured radon concentration for the higher soil permeability \((1\times 10^{-9}, 1\times 10 ^{-8} \hbox { m}^{2})\) and the higher \(^{226}\hbox {Ra}\) mass content values (4500 \(\hbox {Bq\;kg}^{-1})\), especially for high radon pics induced by sudden increase in indoor air pressure drop. Regardless soil \(^{226}\hbox {Ra}\) mass content and crack line configuration in the slab floor, the ECM showed to be conservative for the two-layered soil configuration with the presence of aggregates beneath the slab foundation, generally practiced in buildings constructions.