Regeneration of activated carbon by fenton and photofenton oxidation for the treatment of phenol wastewater

Advanced Oxidation Processes have emerged as promising technologies for the recovery of carbons saturated with aromatic molecules, owing to their potency to degrade a wide range of organic pollutants by the generation of very reactive and non selective free hydroxyl radicals. The purpose of this work is to study the adsorption of phenol on activated carbons (ACs) and the consecutive in-situ regeneration of carbon by Fenton oxidation. Two different processes have been carried out: - the first one is based on a complete batch system in order to investigate the influence of Fe2+ and H2O2 concentrations; - the second one consists in a continuous fixed bed adsorption, followed by a batch circulation of the Fenton’s reagent through the saturated AC bed, to examine the efficiency of the real process. Two different activated carbons have been also studied: a both micro- and mesoporous AC (L27) and an only microporous one (S23). In the batch reactor containing a 1 g/L phenol solution, the optimal conditions found for pollutant mineralization in the homogeneous Fenton system (Fe2+ = 10 mmol/L, [H2O2] = 1000 mmol/L, corresponding to 6.5 times the stoechiometric amount for complete mineralization) are not the best for AC regeneration: a continuous reduction of adsorption capacity of L27 from 100% to 23% is observed after 3 oxidations, due to the decrease of both AC weight and surface area. Higher concentration of Fe2+ (20 mmol/L) and lower concentration of H2O2 (2 times the stoechiometry) lead to a 50% recovery of the initial adsorption capacity during at least 4 consecutive cycles for L27, while about 20% or less for S23. In the consecutive continuous adsorption/batch oxidation process, the regeneration efficiency reaches 30% to 40% for L27 after two cycles whatever the feed concentration (0.1 g/L or 1 g/L of phenol) and less than 10% for S23 (0.1 g/L of phenol). During oxidation step, Total Organic Carbon removal is found to reach a limit, probably due to the formation of Fe3+/organic acid complex, hindering Fe2+ regeneration. Such complexes are stable in usual Fenton conditions, but can be destroyed by UV radiation. A photo-Fenton test performed on L27 indeed shows almost complete mineralization and improved recovery of AC adsorption capacity although not complete (56% after two cycles)

Airborne measurements of biomass burning products over Africa

Ozone has been observed in elevated concentrations by satellites over hitherto believed 'background' areas. There is meteorological evidence that these ozone 'plumes' found over the Atlantic ocean originate from biomass fires on the African continent. Therefore we have investigated ozone and assumed precursor compounds over African regions. The measurements revealed large photosmog layers in altitudes between 1.5 and 4 km. Here we will focus on some results of ozone mixing ratios obtained during the DECAFE 91/FOS experiment and estimate the relevance of biomass burning as a source by comparing the strength of this source to stratospheric input

Phenotyping to dissect the biostimulant action of a protein hydrolysate in tomato plants under combined abiotic stress

Drought and heat stresses are the main constrains to agricultural crop production worldwide. Precise and efficient phenotyping is essential to understand the complexity of plant responses to abiotic stresses and to identify the best management strategies to increase plant tolerance. In the present study, two phenotyping platforms were used to investigate the effects of a protein hydrolysate-based biostimulant on the physiological response of two tomato genotypes (‘E42’ and ‘LA3120’) subjected to heat, drought, or combined stress. The free amino acids in the biostimulant, or other molecules, stimulated growth in treated plants subjected to combined stress, probably promoting endogenous phytohormonal biosynthesis. Moreover, biostimulant application increased the net photosynthetic rate and maximal efficiency of PSII photochemistry under drought, possibly related to the presence of glycine betaine and aspartic acid in the protein hydrolysate. Increased antioxidant content and a decreased accumulation of hydrogen peroxide, proline, and soluble sugars in treated plants under drought and combined stress further demonstrated that the biostimulant application mitigated the negative effects of abiotic stresses. Generally, the response to biostimulant in plants had a genotype-dependent effect, with ‘E42’ showing a stronger response to protein hydrolysate application than ‘LA3120’. Altogether, in this study a fine and multilevel phenotyping revealed increased plant performances under water-limited conditions and elevated temperatures induced by a protein hydrolysate, thus highlighting the great potential biostimulants have in improving plant resilience to abiotic stresses

ClbP is a prototype of a peptidase subgroup involved in biosynthesis of nonribosomal peptides

The pks genomic island of Escherichia coli encodes polyketide (PK) and nonribosomal peptide (NRP) synthases that allow assembly of a putative hybrid PK-NRP compound named colibactin that induces DNA double-strand breaks in eukaryotic cells. The pks-encoded machinery harbors an atypical essential protein, ClbP. ClbP crystal structure and mutagenesis experiments revealed a serine-active site and original structural features compatible with peptidase activity, which was detected by biochemical assays. Ten ClbP homologs were identified in silico in NRP genomic islands of closely and distantly related bacterial species. All tested ClbP homologs were able to complement a clbP-deficient E. coli mutant. ClbP is therefore a prototype of a new subfamily of extracytoplasmic peptidases probably involved in the maturation of NRP compounds. Such peptidases will be powerful tools for the manipulation of NRP biosynthetic pathways

Size-dependent spinodal and miscibility gaps for intercalation in nano-particles

Using a recently-proposed mathematical model for intercalation dynamics in phase-separating materials [Singh, Ceder, Bazant, Electrochimica Acta 53, 7599 (2008)], we show that the spinodal and miscibility gaps generally shrink as the host particle size decreases to the nano-scale. Our work is motivated by recent experiments on the high-rate Li-ion battery material LiFePO4; this serves as the basis for our examples, but our analysis and conclusions apply to any intercalation material. We describe two general mechanisms for the suppression of phase separation in nano-particles: (i) a classical bulk effect, predicted by the Cahn-Hilliard equation, in which the diffuse phase boundary becomes confined by the particle geometry; and (ii) a novel surface effect, predicted by chemical-potential-dependent reaction kinetics, in which insertion/extraction reactions stabilize composition gradients near surfaces in equilibrium with the local environment. Composition-dependent surface energy and (especially) elastic strain can contribute to these effects but are not required to predict decreased spinodal and miscibility gaps at the nano-scale

Periferne osteoporotske frakture osim kuka - epidemiologija i značenje

Fractures are the most serious consequence of osteoporosis. Non-vertebral and non-hip fractures are seldom recognised as important, even though they account for the majority of all fractures. The most prevalent localisations are distal radius, proximal humerus, ribs, clavicle, and the pelvis. According to the results from large phase III clinical trials for placebo groups, their incidence ranges from 4.9 % to 12.0 %. Hospital morbidity data in Croatia in 2006 show that peripheral non-hip fractures ranked among the leading fifteen injuries, accounting for 23.7 % of all injuries in patients aged 60 years and above. Risk factors for non-hip and non-vertebral fractures are similar to other osteoporotic fractures, and the main are low bone mineral density and earlier fractures. Quality of life is considerably affected by these fractures, and medical costs are very high, soaring as high as 36.9 % of all national medical costs in the USA. Nonvertebral non-hip fractures need more attention, which was also recognised by the European regulatory bodies that approve use of anti-osteoporotic drugs.Prijelomi su najozbiljnija posljedica osteoporoze. Iako čine većinu svih fraktura, nevertebralne frakture osim kuka rijetko se prepoznaju kao značajne. Najčešće lokalizacije tih prijeloma su: distalni dio radijusa, proksimalni dio humerusa, rebra, klavikula i zdjelica. Prema rezultatima iz placebo-grupa III. faze velikih kliničkih ispitivanja raspon njihove incidencije iznosi između 4,9 % i 12,0 %. Prema podacima bolničkog pobolijevanja za 2006. g. u Hrvatskoj, među 15 vodećih ozljeda u dobnoj grupi 60 i više godina 23,7 % bile su periferne frakture osim kuka. Čimbenici rizika za nevertebralne frakture osim onih kuka slični su kao i za druge osteoporotske frakture gdje središnje mjesto imaju niska mineralna gustoća kosti i prethodne frakture. Ove frakture imaju velik utjecaj na kvalitetu `ivota, a njihovi su troškovi vrlo visoki, tako da u SAD-u iznose čak 36.9 % svih nacionalnih medicinskih troškova. Nevertebralne frakture osim kuka zahtijevaju veću pozornost, što su i prepoznala europska regulatorna tijela koja odobravaju upotrebu antiosteoporotskih lijekova

Mineral maturity and crystallinity index are distinct characteristics of bone mineral

The purpose of this study was to test the hypothesis that mineral maturity and crystallinity index are two different characteristics of bone mineral. To this end, Fourier transform infrared microspectroscopy (FTIRM) was used. To test our hypothesis, synthetic apatites and human bone samples were used for the validation of the two parameters using FTIRM. Iliac crest samples from seven human controls and two with skeletal fluorosis were analyzed at the bone structural unit (BSU) level by FTIRM on sections 2–4 lm thick. Mineral maturity and crystallinity index were highly correlated in synthetic apatites but poorly correlated in normal human bone. In skeletal fluorosis, crystallinity index was increased and maturity decreased, supporting the fact of separate measurement of these two parameters. Moreover, results obtained in fluorosis suggested that mineral characteristics can be modified independently of bone remodeling. In conclusion, mineral maturity and crystallinity index are two different parameters measured separately by FTIRM and offering new perspectives to assess bone mineral traits in osteoporosis

Spectral and spatial shaping of a laser-produced ion beam for radiation-biology experiments

International audience; The study of radiation biology on laser-based accelerators is most interesting due to the unique irradiation conditions they can produce, in terms of peak current and duration of the irradiation. In this paper we present the implementation of a beam transport system to transport and shape the proton beam generated by laser-target interaction for in vitro irradiation of biological samples. A set of four permanent magnet quadrupoles is used to transport and focus the beam, efficiently shaping the spectrum and providing a large and relatively uniform irradiation surface. Real time, absolutely calibrated, dosimetry is installed on the beam line, to enable shot-to-shot control of dose deposition in the irradiated volume. Preliminary results of cell sample irradiation are presented to validate the robustness of the full system