Gabriel Lazar

Band tail hopping conduction mechanism in highly conductive amorphous carbon nitride thin films

Nitrogenated amorphous carbon (a-C:N) films have been synthesized by radio frequency (rf) magnetron sputtering at various substrate temperatures and rf discharge powers. The temperature dependence of the electrical conductivity has been measured in order to identify the dominant conduction mechanism. The conductivity was found to increase over ten orders of magnitude with increasing growth temperature and discharge power. In the ohmic regime, the conductivity of the investigated a-C:N films is likely dominated by hopping conduction, in good agreement with a model for hopping in localized bandtail states, rather than by extended states band conduction.

Water–poverty relationships in the coastal town of Mbour (Senegal): Relevance of GIS for decision support

Abstract Coastal area is always a zone with complex problems. Due to the attraction they exert, are facing many social problems. Therefore, a coastal city is usually a city with problems. Its extension, caused by the influx of people from different backgrounds, creates an increased demand for services. One of the problems frequently encountered, especially in Senegal, is access to water. The problem of access to water is poorly treated, without being correlated with the urban evolution, i.e. with increasing population and demand growth. The water resource is facing numerous complications such as the lack of integrated management, integration issues at the governance level, where the local factor is often forgotten. The town of Mbour, object of our study, does not come out of that lot, being an attractive coastal city, from an African country. This indicates the need for an integrated management oriented from local to a global basis and not vice versa. The study presented in this paper indicates that a large proportion of the population has not access to a verified drinking water system and uses water from wells or standpipes. Half of the surveyed population (50%) has no access to a water supply system. The water poverty map of the town overlaps with that of the general poverty excepting few neighborhoods. This means that even areas that are not affected by poverty have a very low or poor access to water, which so far remains the perverse effect of the reform of the Senegalese water sector in 1995.

Influence of the substrate-electrode applied bias voltage on the properties of sputtered a-C:H thin films

Highly tetrahedral, hydrogenated amorphous carbon (a-C:H) films have been deposited using rf sputtering of graphite by a magnetron sputter source in Ar/CH4 atmosphere. The deposition rate, the density and the structural properties of the deposited films were studied as a function of applied bias voltage on substrate during deposition. Optical emission spectroscopy was used to diagnose and monitor the plasma discharge. The film structure was studied using IR absorption spectroscopy. For all the films, the percentage of sp3 hydrogen bonding is higher than 80%. The atomic percentage of bonding hydrogen in the films is in the range 40-60% and increases when the applied bias voltage is increasing.

Electrokinetic-Fenton technology for the remediation of hydrocarbons historically polluted sites.

The feasibility of the electrokinetic-Fenton technology coupled with surfactants in the treatment of real historically hydrocarbons polluted soils has been studied. The characterisation of these soils from Spain and Romania was performed and identified as diesel and diesel-motor oil spillages, respectively. Moreover, the ageing of the spillages produced by the soil contamination was estimated showing the historical pollution of the sites (around 11 and 20 years for Romanian and Spanish soils, respectively). An ex-situ electrochemical treatment was performed to evaluate the adequacy of surfactants for the degradation of the hydrocarbons present in the soils. It was found an enhancement in the solubilisation and removal of TPHs with percentages increasing from 25.7 to 81.8% by the presence of Tween 80 for Spanish soil and from 15.1% to 71.6% for Triton X100 in Romanian soil. Therefore, the viability of coupling enhanced electrokinetic and Fenton remediation was evaluated through a simulated in-situ treatment at laboratory scale. The results demonstrated that the addition of the selected surfactants improved the solubilisation of the hydrocarbons and influenced the electroosmotic flow with a slight decrease. The efficiency of the treatment increased for both considered soil samples and a significant degradation level of the hydrocarbons compounds was observed. Buffering of pH coupled with the addition of a complexing agent showed to be important in the treatment process, facilitating the conditions for the degradation reactions that take place into the soil matrix. The results demonstrated the effectiveness of the selected techniques for remediation of the investigated soils.

Some properties of sputtered a-C:H

Highly tetrahedral, hydrogenated amorphous carbon (a-C:H) films have been deposited using rf sputtering of graphite by a magnetron sputter source in Ar/CH 4 atmosphere. The density, the structural properties, the optical band gap and Urbach energy of the deposited films were studied as a function of applied bias voltage on substrate and gas pressure during deposition. The films structure was studied using IR absorption spectroscopy. The variation of the optical band gap is considered to be the result of transition from unsaturated graphitic sp 2 bonds to tetrahedral diamond-like sp 3 bonds in the film. Published by Elsevier Science B.V.

Modifications Induced by UV-Vis Irradiation on DNA Extract of Kiwifruit Investigated by Spectroscopic and Statistic Methods

ABSTRACT Revealing molecular alterations induced on kiwifruit under UV-Vis irradiation requires a discussion of biochemical-cell infrared (IR) fingerprint (900 cm−1–1800 cm−1) bands characteristic of nucleic acids. FTIR-ATR spectroscopy and statistics and nondestructive methods for screening exposure effects induced by irradiation were used. There the irradiation influence on the main molecular bonds (i.e., ν(C-C), νs(PO2−) and νas(PO2−)) can be observed. Regression methods were used for statistical investigations. Two categories of variables were used: the absorbance measured at fixed wavenumber variables and the exposure dose. The bivariate correlations, partial correlations, and polynomial regression methods from SPSS were used for statistical investigations. The obtained results show that FTIR-ATR, in correlation with statistics techniques, might be useful to assess immediate radiation and oxidative-induced damage to nucleic acids. In this case IR spectroscopy can be used successfully to study conformational changes during DNA reversible denaturation especially on the sugar-phosphate vibrations domain.

Electro-Fenton process for implementation of acid black liquor waste treatment

In this work, an eco-friendly solution for the remediation of wastewater generated in the lignin recovery process from eco-industrial paper mill has been proposed in their way towards a more circular economy strategy. Thus, the application of the electro-Fenton process for the degradation of the non-recovered lignin and other organic compounds form a scarcely studied acid black liquor waste (ABLW) was successfully performed. This treatment was able to operate in a range of COD loads (0.5-19.5mgO2·L-1) showing high degradation values of the ABLW determined by the abatement of color, total phenolic content and COD. Then, the optimization of the working conditions for the design of a sustainable treatment system with optimum efficiency was carried out using a response surface methodology. The experiment carried out in the calculated optimal conditions for the electro-Fenton degradation process (current intensity 132.5mA, catalyst dosage of 0.10mM, and temperature 40°C) showed a COD removal of 74.82% and current efficiency 77.79%, close to the theoretical value predicted by the model 73.12% and 77.06%, respectively. In addition, the identification of the final products permitted to confirm the mineralization efficiency.

Effects of Electromagnetic Field on Human’s Health – A Short Review

Nowadays, a lot of scientific publications are focused on the effects of electromagnetic field on environment. Especially during the last years has been intensively studied the influence of radiofrequency electromagnetic fields, mostly used in telecommunications. However, published information is often contradictory or incomplete. Thereby, we aimed to perform a fundamental study of both, literature published in internationally recognized journals as well as results published in national scientific journals and available reports of investigations conducted by research institutions in the former USSR. It is known that starting with ‘70s this research direction has developed very quickly and an impressive number of papers have been published in this field.

DRIVING FORCES AFFECTING THE ADOPTION OF ECO-INNOVATION: A SURVEY ON VACUUM SEWER SYSTEMS

The article studies the adoption of eco-innovation using the diffusion dynamic as a paradigm for investigating the environmental reform in providing public goods. The study focused on the wastewater collection systems and analyzed how the structure of the market, socio-cultural conditions, geographic proximity and the Gross Domestic Product level measured the acceptance or rejection of eco-innovation. The authors investigated the data in order to test three hypotheses, respectively, the influence of the period of adoption, general country economic performance, and neighborhood conditions in eco-innovation adoption. The hypotheses were tested using statistical and geostatistical techniques. The study concluded that the adoption rate slows as the saturation level is approached and early adopting countries have a broader uptake of the innovation than do latecomers, even though the latecomers enjoy the benefits of leapfroggers. In addition, the study found that geographic proximity influenced who was an early adopter and who was a laggard. The results illustrated that the general economic performance of a state does not directly influence eco-innovation adoption.

Spectral Investigation of Phosphorus Compounds in Spinacia Oleracea Using Fourier Transform Infrared Method

The study uses the Fourier transform infrared spectroscopy method to evaluate the influence of phosphogypsum from the soil on the growth and accumulation of nutrients in Spinacia oleracea. Attenuated total reflectance spectra of Spinacia oleracea roots and stems originated from plants cultivated on 28% to 52% phosphogypsum enriched soil have been studied in the 4000–600 cm−1 area. The structure of the infrared absorption bands for spinach roots and stems and for the soil where plants were grown was analyzed. Thus, it was observed that phosphorus–oxygen bonds contribution can be identified both in roots and stems absorption spectra. The significance of the research is the possibility to use the infrared investigation as rapid technique, particularly useful for agriculture, to study the extraction and assimilation process of the compounds containing phosphorus and nitrogen from the soil in which the spinach seedlings grew. In the case of this study, it was observed that the absorption of phosphorus in the spinach roots and stems has not the same effect. The analysis of obtained data indicated that the assimilation of phosphorus from phosphogypsum enriched soil induces changes in spinach roots structure that are most likely due to an increase synthesis of proteins, rather than to a decrease in carbohydrates quantity.