Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

It is very important to understand the interaction between plastics and environment in ambient conditions. The plastics degrade because of this interaction and often their surface properties change resulting in the creation of new functional groups. The plastics after this change continue to interact with the environment and biota. It is a dynamic situation with continuous changing parameters. Polyethylene, polypropylene, and polyethylene terephthalate (PET) degrade through the mechanisms of photo-, thermal, and biodegradation. The three polymers degrade with different rates and different pathways. Under normal conditions, photo- and thermal degradation are similar. For polyethylene, photo-degradation results in sharper peaks in the bands which represent ketones, esters, acids, etc. on their infrared spectrum. The same is true for polypropylene but this polymer is more resistant to photo-degradation. The photo-oxidation of PET involves the formation of hydroperoxide species through oxidation of the CH2 groups adjacent to the ester linkages and the hydroperoxides species involving the formation of photoproducts through several pathways. For the three polymers, interaction with microbes and formation of biofilms are different. Generally, biodegradation results in the decrease of carbonyl indices if the sample has already been photo-degraded by exposure to UV. Studies with environmental samples agree with these findings but the degradation of plastics is very subjective to the local environmental conditions that are usually a combination of those simulated in laboratory conditions. For example, some studies suggested that fragmentation of plastic sheet by solar radiation can occur within months to a couple of years on beaches, whereas PET bottles stay intact over 15 years on sea bottoms.

Degradation of Various Plastics in the Environment

Effective conversion of waste polyester–cotton textile to ethanol and recovery of polyester by alkaline pretreatment

In the last few years, several studies have investigated microplastics (MPs) in marine ecosystems, but data monitoring and assessing the occurrence in freshwater environments are still scarce. The present study aims to investigate the occurrence, distribution, and chemical composition of MP pollution in Vesijarvi lake and Pikku Vesijarvi pond close to the city of Lahti (Finland) in winter. Sediment, snow, and ice core samples were collected near the shore of these two aquatic systems. MPs were analysed and identified by a non-destructive method using Fourier transform infrared spectroscopy (FTIR) 2D imaging. The mean concentrations of MPs detected in sediment, snow, and ice samples were 395.5 ± 90.7 MPs/kg, 117.1 ± 18.4 MPs/L, and 7.8 ± 1.2 MPs/L, respectively. FTIR results showed the predominant abundance of microplastics, such as polyamides (up to 53.3%), polyethylene and polypropylene (up to 17.1%), and natural fragments such as cellulose (up to 45.8%) and wool (up 18.8%) in the same size range. The potential release of MPs arising from stormwaters and sport and recreational activities was evidenced.

/pdf/assessment-of-microplastic-pollution-occurrence-and-p3bt4xsmrv.pdf

Assessment of microplastic pollution: occurrence and characterisation in Vesijarvi lake and Pikku Vesijarvi pond, Finland

A novel approach of solid waste management via aromatization using multiphase catalytic pyrolysis of waste polyethylene.

The degradation induced by MeV He+ ions onto polyethylene terephthalate (PET) is investigated as a function of fluence and electronic stopping power (dE/dx)e. Stack samples of four 3.6 μm PET films are irradiated by 3.5 MeV He+ under vacuum and room temperature at fluence ranging from 1013 to 1.5 × 1015 He+ cm−2. The entrance energies range from 3.5 MeV for the front film to 0.573 MeV for the rear one at the beginning of the irradiation and the corresponding mean (dE/dx)e lie for pristine PET between 158 and 264 keV/μm. A Fourier transform infrared spectroscopy (FTIR) analysis is undertaken. The different stack films present similar damages with magnitude increase as the fluence goes up. Moreover, higher is the electronic stopping power (dE/dx)e more important is the damage. The evolution of the normalized integrated absorbance A( ϕ )/A0 of the internal reference 1410 cm−1 band as a function of the fluence ϕ presents a complex behavior characterized by a two-exponential decay associated to low and high fluence range. The analysis reveals clearly that the A( ϕ )/A0 of the characteristic benzene ring 1577 cm−1 band remains steady till fluence around 3 × 1014 He+ cm−2 and then decreases smoothly as fluence increases. The band appearing at 1610 cm−1, assigned to mono substituted benzene, presents an integrated absorbance A( ϕ ) which rises progressively and levels off beyond a critical fluence around 4 × 1014 He+ cm–2. The cross section of the creation of the monosubstituted benzene lies between 3 × 10−15 and 6 × 10−15 cm2 for (dE/dx)e = 158 and 264 keV/μm, respectively. Drastic loss of crystallinity is induced by the MeV He+ ion irradiation in the polymer. The amorphization is monitored by the evolution of the specific bands of the trans and gauche ethylene glycol residue conformations. A sudden drop in the integrated absorbance of the 1340 cm−1 band which characterizes the trans conformation is observed at fluence around 2 × 1014 He+ cm−2. On the other hand, a drastic increase is present in the integrated absorbance of the gauche conformation 1370 cm−1 band that pairs up with 1340 cm−1 band. This observation is a clear indication of the conversion of the trans ethylene glycol residue to gauche one under irradiation.

FTIR analysis of polyethylene terephthalate irradiated by MeV He

For the future, one of the biggest challenge faced to the technologies of flat panel display and various optoelectronic and photovoltaic devices is to find an alternative to the use of transparent conducting oxides like ITO. In this new approach, the objective is to grow high conductive thin-layer graphene (TLG) on the top of diamond-like carbon (DLC) layers presenting high performance. DLC prepared by pulsed laser deposition (PLD) have attracted special interest due to a unique combination of their properties, close to those of monocrystalline diamond, like its transparency, hardness and chemical inertia, very low roughness, hydrogen-free and thus high thermal stability up to 1000 K. In our future work, we plane to explore the synthesis of conductive TLG on top of insulating DLC thin films. The feasibility and obtained performances of the multi-layered structure will be explored in great details in the short future to develop an alternative to ITO with comparable performance (conductivity of transparency). To select the best DLC candidate for this purpose, we focus this work on the physicochemical properties of the DLC thin films deposited by PLD from a pure graphite target at two wavelengths (193 and 248 nm) at various laser fluences. A surface graphenization process, as well as the required efficiency of the complete structure (TLG/DLC) will clearly be related to the DLC properties, especially to the initial sp3/sp2 hybridization ratio. Thus, an exhaustive description of the physicochemical properties of the DLC layers is a fundamental step in the research of comparable performance to ITO.

/pdf/high-performance-diamond-like-carbon-layers-obtained-by-386ukh1o50.pdf

High performance diamond-like carbon layers obtained by pulsed laser deposition for conductive electrode applications

Matter losses of polyethylene terephthalate (PET, Mylar) films induced by 1600 keV deuteron beams have been investigated in situ simultaneously by nuclear reaction analysis (NRA), deuteron forward elastic scattering (DFES) and hydrogen elastic recoil detection (HERD) in the fluence range from 1 × 10 14 to 9 × 10 16  cm −2 . Volatile degradation products escape from the polymeric film, mostly as hydrogen-, oxygen- and carbon-containing molecules. Appropriate experimental conditions for observing the composition and thickness changes during irradiation are determined. 16 O(d,p 0 ) 17 O, 16 O(d,p 1 ) 17 O and 12 C(d,p 0 ) 13 C nuclear reactions were used to monitor the oxygen and carbon content as a function of deuteron fluence. Hydrogen release was determined simultaneously by H(d,d)H DFES and H(d,H)d HERD. Comparisons between NRA, DFES and HERD measurements show that the polymer carbonizes at high fluences because most of the oxygen and hydrogen depletion has already occured below a fluence of 3 × 10 16  cm −2 . Release curves for each element are determined. Experimental results are consistent with the bulk molecular recombination (BMR) model.

Method to measure composition modifications in polyethylene terephthalate during ion beam irradiation

The stopping cross sections e(E) of silicon for protons and alpha particles have been measured over the velocity range 0.3–1.2 MeV/u from a Si//SiO2//Si (SIMOX) target using the Rutherford backscattering spectrometry (RBS) with special emphasis put on experimental aspects. A detection geometry coupling simultaneously two solid-state Si detectors placed at 165° and 150° relative to each side of the incident beam direction was used to measure the energies of the scattered ions and determine their energy losses within the stopping medium. In this way, the basic energy parameter, Ex, at the Si/SiO2 interface for a given incident energy E0 is the same for ions backscattered in the two directions off both the Si and O target elements, and systematic uncertainties in the e(E) data mainly originating from the target thickness are significantly minimized. A powerful computer code has been elaborated for extracting the relevant e(E) experimental data and the associated overall uncertainty that amounts to less than 3%. The measured e(E) data sets were found to be in fair agreement with Paul’s compilation and with values calculated by the SRIM 06 computer code. In the case of 4He+ ions, experimental data for the γ effective charge parameter have been deduced by scaling the measured stopping cross sections to those of protons crossing the same target with the same velocity, and compared to the predictions of the SRIM 06 computer code. It is found that the γ-parameter values generated by the latter code slightly deviate from experiment over the velocity region around the stopping cross section maximum where strong charge exchanges usually occur.

Stopping of 0.3–1.2 MeV/u protons and alpha particles in Si

A 3.7 MeV He+ ion beam was simultaneously used for Polyethylene Terephtalate (PET) film degradation and characterization. To enhance the potentialities of the characterization method, a multi-detector Ion Beam Analysis (IBA) technique was used. The stoichiometry change of the PET target following the irradiation is quantified at a beam fluence varying between 7 × 1013 and 1.8 × 1016 He+ cm−2. The damage induced in PET films by He+ bombarding was analyzed in-situ simultaneously through Rutherford Backscattering Spectrometry (RBS), Particle Elastic scattering Spectrometry (PES) and Hydrogen Elastic Recoil Detection (ERD). Appropriate experimental conditions for the observation of absolute changes in composition and thickness during irradiation were determined. The oxygen and carbon content evolution as a function of the ion fluence was monitored by He+ backscattering whereas the hydrogen content was measured by H(α, H)α collisions in which both the scattered He+ ions and the recoiling H could be observed. The present study reveals that, at the highest fluence 1.8 × 1016 He+ cm−2, the PET films have lost approximately 15% of the carbon, more than 45% of the hydrogen and 85% of the oxygen of the amount contained in the pristine sample. The energy shift of recoiling H+ ions at a forward angle 45° was followed in order to study the mass loss effect. The experimental results are consistent with the bulk molecular recombination model. Based on the results, hydrogen, oxygen and carbon release cross sections are determined. For hydrogen, comparison with deuteron irradiation indicates a cross section linear dependence on the stopping power.

M. Abdesselam

Papers

FTIR analysis of polyethylene terephthalate irradiated by MeV He

High performance diamond-like carbon layers obtained by pulsed laser deposition for conductive electrode applications

Method to measure composition modifications in polyethylene terephthalate during ion beam irradiation

Stopping of 0.3–1.2 MeV/u protons and alpha particles in Si

Stoichiometry evolution of polyethylene terephtalate under 3.7 MeV He+ irradiation