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Eva era nera. La scoperta di ‘Eva mitocondriale’ nelle pratiche visuali dei rotocalchi italiani
No full textThis article examines the iconographies that shaped Italian public debate following the introduction, in 1987 at the University of California, Berkeley (by Rebecca Cann, Mark Stoneking, and Allan C.Wilson), of a new female figure in studies on human origins and population diversity – later known as ‘Mitochondrial Eve’ (also referred to as ‘African Eve’ and ‘Black Eve’).
Through an analysis of the major illustrated magazines then in circulation, the study explores both the national and international trajectories and the visual reception of this ‘scientific earthquake’, which contributed to challenging the multiregional model of human origins. On the one hand, it was portrayed as a profound upheaval of the evolutionary order; on the other, as the notion of a common ancestor (a lucky mother) of all contemporary human populations. In particular, the article investigates the most widespread visual practices – devoting special attention to the presence or absence of photographic representations, which had long served as a key tool in depicting diverse human groups over the course of racist thinking – to discern whether and how, by the late 1980s, the iconographies of progress and human difference underwent significant changes in light of the interplay between science, racial discourse, and public debate.
Ultimately, the goal is to contribute to the historicization of antiracist sensibilities in Italy, marked by a persistent appeal to scientific authority as a source of legitimacy at a pivotal moment characterized by the coexistence of Afrophobia and Afromania.
Key words: Mitochondrial Eve; visual culture; illustrated press; antiracism; Genetic
PAEDIATRIC-ONSET PRIMARY SCLEROSING CHOLANGITIS: CLINICAL COURSE AND OUTCOME
Full text linkABSTRACT
BACKGROUND AND AIMS
The natural history of paediatric onset PSC and PSC/AIH overlap syndrome is poorly known. Thus, this study was aimed at evaluating the clinical course and outcome of patients with a paediatric onset of disease.
MATERIALS AND METHODS
Between December 1993 and December 2011, thirty-five patients (median age at diagnosis 15 years), with confirmed PSC by cholangiography (ERC) and PSC/AIH by cholangiography and the modified score for AIH, were traced at Helsinki University Central Hospital. Clinical characteristics (symptoms and signs, associated diseases), diagnostic procedures (lab tests, liver biopsy, ERC) and long-term follow-up (mortality, liver transplantation, recurrence of the disease in the graft, malignancy) were reassessed until December 2013.
RESULTS
The original diagnosis was PSC in 22 children (63%) and PSC/AIH overlap syndrome in 13 (37%). At diagnosis most of the children had an insidious onset and most an associated IBD, being UC the most common form. Still, 4/35 (11%) had cirrhosis. Endoscopic retrograde cholangiography during follow-up was available for all of the patients and images showed a progression of intra-hepatic disease in 13/28 (46.4%) (p=0.0102). In the last follow-up (median 8 years), all patients were alive. Twenty-eight out of 35 patients (80%) and 13/35 patients (40%) were taken UDCA and immunosuppressive therapy, respectively; 3 patients were without treatment. Transaminases and GGT improved significantly. Four patients (11%) had undergone liver transplantation (after a median 7.5 years) and one was listed; and additional patient was transplanted because of Budd-Chiari syndrome. No difference in graft free survival was seen between patients with PSC and PSC/AIH. Three patients (two with PSC and one with PSC/AIH overlap syndrome) presented with cirrhosis. No malignancy occurred.
CONCLUSION
The clinical outcome of primary sclerosing cholangitis and overlap syndrome seems comparable including their progression to cirrhosis and requirement for liver transplantation
BIOHYDROGEN PRODUCTION FROM AGRICULTURAL AND LIVESTOCK RESIDUES WITHIN AN INTEGRATED BIOENERGY CONCEPT
Full text linkConcerns about energy security, fossil fuel prices, and climate change issues, are leading to increasing renewable energy demand. Hydrogen is considered as one of the main possible energy carriers in future, due to its environmental (it can be converted to energy with the solely emission of water) and energetic (energy content of 120 MJ/kg, three times higher of the gasoline content of 44 MJ/kg) unique properties.
If hydrogen is currently being produced mainly by fossil sources, its production from renewable sources answers to the demand of more environment-friendly exploiting alternatives, possibly leading to a renewable-based hydrogen economy. Biomasses are an important renewable source ranging from energy-dedicated crops to livestock waste effluents, agro-industrial wastewaters, food-processing industry residues and organic fractions of the municipal solid waste (OFMSW). Thus the agricultural sector may acquire a renewed importance in the mid-term as a producer of energy sources for renewable biohydrogen production.
Among the biological ways to exploit biomasses for hydrogen production, this thesis focused its interest on anaerobic dark fermentation, which can simultaneously guarantee the production of an high-value product (H2) at high evolution rates and the treatment of wastes, thus transformed from an environmental pollution and greenhouse gases emissions source into a valuable resource. If on the one hand this process has lots in common with anaerobic digestion, which already is a well-established technology for treating different biomass types in real-scale plants, on the other hand it is a relatively new approach, which needs to be further studied for improving its performances and being concretely applicable.
As a matter of fact, the main disadvantage of dark fermentation is its relatively low yield, compared to other bio-hydrogen production methods, which typically are between 2.4 and 3 mol H2/mol glucose. This represents just the 20-25% of the 12 mol of H2 theoretically obtainable by glucose fermentation. Therefore, generally two different (but not mutually exclusive) options could be chosen for improving the process and making it ready for full-scale applications: the optimization of the biological, biochemical, chemical-physical operative parameters that regulate process; or the coupling of this bioprocess with other technologies capable of exploiting the organic matter not fully used by the dark fermentative approach. For example, Microbial Electrolysis Cells (MECs) are able to biologically oxidize the organic matter (from simple substrates like volatile fatty acids, lactic acid, glucose, cellulose, to actual wastewaters) releasing electrons from an anode to a cathode where potentially pure hydrogen can be formed from protons in the water.
Papers I and II basically belong to the first strategy. In Paper I indeed, two waste biomasses were co-digested: in consideration that in the Po Valley area (Italy) swine manures (SM) are yearly produced at high waste density levels and could be a cause of environmental problems, this waste was used as a co-substrate for biohydrogen production by the thermophilic fermentation of easily degradable and carbohydrate-rich materials, such as fruit and vegetable market waste (FVMW). Biohydrogen production rates and process stability were thus simultaneously maximized, thanks to the endogenous buffer capacity of manure, through the combination of a suitable composition (as FVMW/SM) of the feeding material and the hydraulic retention time (HRT) of the process. Thus, livestock manure represented not only a renewable source for supplying the production of biohydrogen, but also a source of alkali to be used for avoiding the addition of exogenous chemicals (alkali) to maintain the pH, and so the metabolic pathways and bacterial communities, into an optimal domain for biohydrogen production.
To further study and optimize the bio-H2 production in laboratory-scale processes, but also to find applicable tools for favoring dark fermentation application in full-scale biogas plants, Paper II succeeded in obtaining mixed microbial cultures from natural sources (soil-inocula and anaerobically digested materials) which reached high hydrogen yields with glucose and were used to explore the potential of bio-hydrogen production from four organic substrates of possible interest for full-scale plants (market bio-wastes, maize silage, swine manure, OFMSW). In direct prosecution of the positive co-digestion results shown in Paper I and looking for future transfer of this bioprocess technical solutions to full-scale systems, Paper II used the enriched mixed microflora for evaluating the co-fermentation of a mixture of OFMSW and swine manure in a lab-scale continuously-fed CSTR (continuously stirred tank reactor) digester. Despite the good results obtained, our study suggested that further efforts are needed for future applications of effective biohydrogen fermentation in full-scale plants.
Paper III and IV are more focused on the second scientific strategy. Paper III joins the interest toward implementation of bio-H2 in full-scale plants and the strategy of improving the overall recovery of the energy contained in the biomass associating hydrogen production to other bioprocesses. Many authors report that the two-stage anaerobic digestion (AD) process, if compared to traditional and extensively real-scale applied single-stage AD, has also other advantages, such as differentiating the biofuel production (bio-hydrogen and bio-methane), potentially reducing the plant dimensions and costs, improving the overall biogas production yields and allowing higher CH4 concentrations in the biogas produced in the second stage, thus decreasing the biogas purification costs. Therefore, a two-stage laboratory-scale CSTR anaerobic digester, fed with a mixture of agricultural and livestock residues, was monitored for a long run (approximately 700 hours) and compared to a similar one-stage reactor. This study obtained a good hydrogen yield per kg of biomass treated and partially confirmed the advantages previously illustrated, even if it reached almost the same overall energy recovery of the single stage process.
Aiming at other possible biological strategies to improve the energy and hydrogen recovery efficiency with the use of effluents from a first dark fermentative stage, a relatively new electrohydrogenesis device (MEC) was studied. Paper IV explores the rate and the yield of biogas (a mixture of H2, CH4 and CO2) produced by MEC exploiting an actual industrial wastewater with high methanol content, a compound never before reported to be used in a MEC device. The energetic recovery and treatment performance of the process was evaluated and also compared with a simulation of anaerobic digestion of the same wastewater, revealing the economical competitiveness of the MEC technology with the AD process. This leads to future research perspectives aiming to realize a laboratory-scale two-stage reactor with a MEC using the volatile-rich effluent of a first dark fermentative stage
Can two-stage instead of one-stage anaerobic digestion really increase energy recovery from biomass?
No full textThe supremacy of two-stage on traditional one-stage anaerobic digestion (AD), in terms of overall energy recovery (ER) from biomass has often been proved. However, the process conditions ensuring this result, as well as the reasons for higher efficiency, have always been unclear. In this work, a new standardized approach is proposed: optimization at lab-scale of both hydrogen and methane generation processes allowed comparing the maximum potential ER of both two-stage (as H2+CH4) and one-stage AD (as CH4). Relatively high bio-hydrogen yields were obtained testing four different organic substrates (ER of 1-1.6MJkg-1VS-added). Biomethane generation resulted in ER in the range of 9-19MJkg-1VS-added., similarly for two-stage and one-stage systems. The overall ER resulted in significantly higher (8%-43%) for the two-stage in the large majority of experimental conditions and never significantly lower. These preliminary results should drive further research to better understand the conditions that can drive the two-stage AD to higher performance
An operational strategy to produce Bio-hydrogen : the use of digestate for process control
Full text linkA semi-continuous digester was fed twice a day with a concentrated solution of glucose (100 g l-1) and monitored for a 30-days period, with the aim of testing the possibility of utilizing the digestate of a traditional biogas plant, after a heat-shock at 100oC, for controlling process parameters (organic loading rate OLR, pH, volatile fatty acids VFA concentration), by adding it to the fresh substrate at a ratio R of the total feeding volume. The process resulted instable for OLR=10 gVS L-1and R=0.7, while more stable for OLR of 5 gVS L-1and R=0.85. The maximum bio-hydrogen production rate in stable conditions was 100 NmLH2 h-1 and the conversion yields were 1.7 - 1.8 molH2 mol-1glucose. The produced biogas showed always complete absence of methane
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