Synthesis and preparation of acid capped CdSe nanocrystals as successful adsorbent and photocatalyst for the removal of dyes from water and its statistical physics analysis

In this study, mercaptosuccinic acid capped CdSe nanocrystals were successfully synthesized and used as photocatalyst for the effective removal of methylene blue (MB) inaqueous solution under visible light and sunlight irradiations including its analysis with statistical physics theory. Dye adsorption properties of these nanocrystals were investigated via experimental kinetics and equilibrium studies. These experimental data were modeled via the application of statistical physics theory to explain the corresponding adsorption mechanism and to characterize the steric and energetic parameters involved in the dye removal. A maximum adsorption capacity of 27.07 mg g^-1 (80% of dye removal) was observed in 10 min using an initial concentration of 30 mg L^-1. Statistical physics calculations indicated that the adsorption energy was lower than 40 kJ mol^-1. It was also established that the dye adsorption was associated to the electrostatic interactions and hydrogen bonding where dye aggregation and multi-molecular adsorption were expected. Overall, the dye removal was a spontaneous, feasible and exothermic. It was concluded that adsorption properties of CdSe-MSA nanocrystals improved the dye photo-catalytic degradation efficiency under visible light thus achieving up to 80% degradation efficiency in 60 min. The synergic effect of adsorption and photo-catalytic degradation performance was mainly due to the surface area (136.43 m² g^-1), small size (3.7 nm), and structural defects (selenium vacancies S_e, interstitial of cadmium I_Cd) of CdSe nanocrystals, which enhanced both the response of these nanomaterials to visible light and their photo-catalytic activity. In summary, these nanocrystals are promising materials to be used in wastewater treatment under sunlight for the removal of organic compounds like dyes.

Fast and effective catalytic degradation of an organic dye by eco-friendly capped ZnS and Mn-doped ZnS nanocrystals

Undoped and manganese doped ZnS nanocrystals encapsulated with thioglycolic acid (ZnS-TGA) were synthesized and characterized with different techniques, and finally tested in the photodegradation of a methyl orange in aqueous solution under UV and sunlight irradiations. FTIR and X-ray diffraction results confirmed the functionalization of these nanocrystal surface by thioglycolic acid and the formation of crystalline structures of ZnS and Mn-doped ZnS with cubic and hexagonal phases. Calculated average size of ZnS nanocrystals was in the range of 2-3 nm. It was observed a blue shift of the absorbance threshold and the estimated bandgap energies were higher than that of Bulk ZnS thus confirming the quantum confinement effect of charge carriers. Photoluminescence spectra of ZnS nanocrystals exhibited emission in the range of 410-490 nm and the appearance of an additional emission band around 580 nm (2.13 eV) connected to the ⁴T₁ → ⁶A₁ transition of the Mn²⁺ions. Photodegradation of methylene orange with undoped and Mn-doped ZnS-TGA nanocrystals was investigated. Dye adsorption prior to photocatalysis using nanocrystals was studied via kinetic and equilibrium experiments. The maximum dye adsorption capacity on doped ZnS-TGA was ~ 26.98 mg/g. The adsorption kinetic was found to follow the pseudo-second-order kinetic model. A statistical physics model was used to analyze the equilibrium data where the calculated adsorption energy was 17-18 kJ/mol. It was concluded that the dye adsorption was associated to the hydrogen interaction where the removal process was feasible and multi-molecular at 25 °C. The photocatalytic activity of undoped ZnS nanoparticles under UV irradiation showed better efficiency than doped nanocrystals thus indicating that manganese doping generated a dropping of the photocatalytic degradation of the dye. Dye degradation efficiency of 81.37% using ZnS-TGA nanocrystals was achieved after 6 min, which indicated that ZnMnS-TGA nanocrystals may be considered an alternative low cost and environmental friendly material for facing water pollution caused by organic compounds via photodegradation processes.

Harnessing drug/radiation interaction through daily routine practice: Leverage medical and methodological point of view (MORSE 02-17 study)

BACKGROUND

Safety profile of the interaction between anticancer drugs and radiation is a recurrent question. However, there are little data regarding the non-anticancer treatment (NACT)/radiation combinations. The aim of the present study was to investigate concomitant NACTs in patients undergoing radiotherapy in a French comprehensive cancer center.

METHODS

A prospective cross-sectional study was conducted. All cancer patients undergoing a palliative or curative radiotherapy were consecutively screened for six weeks in 2016. Data on NACTs were collected.

RESULTS

Out of 214 included patients, a NACT was concomitantly prescribed to 155 patients (72%), with a median number of 5 NACTs per patient (range: 1-12). The most prescribed drugs were anti-hypertensive drugs (101 patients, 47.2%), psychotropic drugs (n = 74, 34.6%), analgesics (n = 78, 36.4%), hypolipidemic drugs (n = 57, 26.6%), proton pump inhibitors (n = 46, 21.5%) and antiplatelet drugs (n = 38, 17.8%). Although 833 different molecules were reported, only 20 possible modifiers of cancer biological pathways (prescribed to 74 patients (34.5%)) were identified. Eight out of the 833 molecules (0.9%), belonging to six drug families, have been investigated in 28 ongoing or published clinical trials in combo with radiotherapy. They were prescribed to 63 patients (29.4%).

CONCLUSION

Drug-radiation interaction remains a subject of major interest, not only for conventional anticancer drugs, but also for NACTs. New trial designs are thus required.

[Fetal pathology study of 88 cases of letal spina bifida]

Lethal spina bifida continue to be frequent in Tunisia; we report 88 cases of letal spina bifida: 1.05 per thousand births. This pathology was more frequent with women. The up letal spina bifida situated is predominant with female and the dow spina bifida situated is frequent with male. We have noted an association with anencephalia (46 cases) and hydrocephaly (21 cases). Prevention is based on obstetric health care and hygiene dietetic advices to avoid alimentary deficit.