Assessing the environmental performance and sustainability of bioenergy production in Sweden: A life cycle assessment perspective

Bioenergy is one of the most dynamic and rapidly changing sectors of the global energy economy. The use of food crops for conversion to biofuel has been criticized for several reasons, among which its competition with the global food chain. Instead, lignocellulosic substrates are claimed to provide a bioenergy alternative without competing with food demand. This is particularly true when dealing with residues or waste. In this paper, we explored the environmental performance and sustainability of a bioenergy production system that integrates wastewater treatment, willow farming, and a Combined Heat and Power plant (CHP) located in Enköping (Sweden). Several methodologies for environmental assessment are integrated in this study within a life cycle perspective to investigate material and energy requirements as well as emissions and related impacts of the whole bioenergy production chain. Results show that full integration of different subsystems of a productive network is a desirable option for bioenergy production, within a zero emission oriented production pattern. The investigated wood biomass powered CHP plant was able to co-generate heat and electricity with high production efficiency and much better environmental performance and sustainability than fossil fuel based power plants.     

Modelling and simulation of a catalytic autothermal methane reformer with Rh catalyst

A model of a ATR fixed bed reactor with Rh catalyst has been developed and validated on the basis of experimental results.Experiments have been conducted in a small scale reactor and solid temperature profiles have been measured with IR camera. Temperature profiles present high peak temperature at reactor entrance as consequence of the partial separation in space of the reforming and oxidation reactions. Thus, the kinetic model for Rh catalyst refers to an indirect scheme including a shift factor which is crucial for good predictive capabilities of the reactor model. The model validation has been conducted by comparing solid temperature profiles with those obtained experimentally at different feed compositions, total flow rate and preheating temperatures. The model well describes the experimental results in all the investigated operating conditions. The validated model has been then used to analyze the effect of thermal conductivity and of the flow rate on overall reactor performances.     

Thermoelastic vibration of doubly-curved nano-composite shells reinforced by graphene nanoplatelets

Abstract

The thermo-mechanical vibration characteristics of doubly-curved nano-composite shells reinforced by graphene nanoplatelets are investigated by considering a uniform distribution of graphene and a first-order shear deformation theory. The mechanical properties of the nano-composite shells are estimated by using the modified Halpin–Tsai model. The governing equations are first derived by a variational formulation using Hamilton’s principle and are solved using the Galerkin technique. Numerical results are presented for various shell curvatures and compared with those available in the archival literature. Furthermore, parametric studies are offered to highlight the significant influence of graphene nanoplatelets’ weight fraction, dimensions of graphene nanoplatelets, and temperature variation, on the free vibration of the nano-composite shells.     

Formation of RNA Phosphodiester Bond by Histidine‐Containing Dipeptides

A new scenario for prebiotic formation of nucleic acid oligomers is presented. Peptide catalysis is applied to achieve condensation of activated RNA monomers into short RNA chains. As catalysts, L ‐dipeptides containing a histidine residue, primarily Ser‐His, were used. Reactions were carried out in selforganised environment, a water‐ice eutectic phase, with low concentrations of reactants. Incubation periods up to 30 days resulted in the formation of short oligomers of RNA. During the oligomerisation, an active intermediate (dipeptide–mononucleotide) is produced, which is the reactive species. Details of the mechanism and kinetics, which were elucidated with a set of control experiments, further establish that the imidazole side chain of a histidine at the carboxyl end of the dipeptide plays a crucial role in the catalysis. These results suggest that this oligomerisation catalysis occurs by a transamination mechanism. Because peptides are much more likely products of spontaneous condensation than nucleotide chains, their potential as catalysts for the formation of RNA is interesting from the origin‐of‐life perspective. Finally, the formation of the dipeptide–mononucleotide intermediate and its significance for catalysis might also be viewed as the tell‐tale signs of a new example of organocatalysis.     

Cystic fibrosis transmembrane conductance regulator is an epithelial cell receptor for clearance of Pseudomonas aeruginosa from the lung

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride ion channel, but its relationship to the primary clinical manifestation of CF, chronic Pseudomonas aeruginosa pulmonary infection, is unclear. We report that CFTR is a cellular receptor for binding, endocytosing, and clearing P. aeruginosa from the normal lung. Murine cells expressing recombinant human wild-type CFTR ingested 30-100 times as many P. aeruginosa as cells lacking CFTR or expressing mutant DeltaF508 CFTR protein. Purified CFTR inhibited ingestion of P. aeruginosa by human airway epithelial cells. The first extracellular domain of CFTR specifically bound to P. aeruginosa and a synthetic peptide of this region inhibited P. aeruginosa internalization in vivo, leading to increased bacterial lung burdens. CFTR clears P. aeruginosa from the lung, indicating a direct connection between mutations in CFTR and the clinical consequences of CF.     

Advanced overtaking behaviors for blocking opponents in racing games using a fuzzy architecture

In car racing, blocking refers to maneuvers that can prevent, disturb or completely block an overtaking action by an incoming car. In this paper, we present an advanced overtaking behavior that is able to deal with opponents implementing blocking strategies of various difficulty level. The behavior we developed has been integrated in an existing fuzzy-based architecture for driving simulated cars and tested using The Open Car Racing Simulator (TORCS). We compared a driver implementing our overtaking strategy against four of the bots available in the TORCS distribution and Simplix, a state-of-the-art driver which won several competitions. The comparison was carried out against opponents implementing three blocking strategies of increasing difficulty and two different scenarios: (i) a basic scenario with one opponent on a straight stretch to overtake as quickly as possible; (ii) an advanced scenario involving a race on a non-trivial track against several opponents. The results from the basic scenario show that our strategy can always overtake the opponent car; in particular, our strategy is slightly more risky than the other ones and may result in a little damage, however, all the other controllers show a more careful and safe policy that often prevents them to complete an overtaking maneuver. When racing against several opponents on complex tracks, our strategy results in the best trade-off between the time spent being blocked by an opponent ahead and the number of overtaking maneuvers completed.     

Novel tri- and tetrafunctional cholic acid-based initiators for the synthesis of star-shaped poly(L-lactide)s

In this investigation, two novel multifunctional initiators for ring-opening polymerization were synthesized in three steps starting from cholic acid. Thus, cholic acid (1a) and its methyl ester (1b) were quantitatively transformed, via solvent-free reaction with succinic anhydride, to the corresponding 3, 7, 12-tri-hemisuccinate derivatives (3a-b). The polyacidic compounds (3a-b) were treated with thionyl chloride affording the corresponding acyl chlorides 4a-b which, in turn, were reacted with ethylene glycol to give the derivatives 2a-b having three and four primary alcohol end groups. These compounds, fully characterized by ¹H, ¹³C NMR and mass spectrometry, have been assessed as initiators in the ring-opening polymerization of L-lactide using stannous octanoate as catalyst. The resulting three- and four-armed star-shaped poly(L-lactide)s, which were characterized by ¹H NMR, SEC, DSC and TGA analysis, were amorphous, and their glass transition temperatures ranged from 13.7 to 36.5 °C. Additionally, some cholic acid-based star-shaped polylactic structures recently published have been critically reconsidered showing that these molecules, described as star polymers, were actually linear polymers.     

A new high performance battery-operated electrometer

Design and analysis of a new low-noise, fast-response, high-sensitivity, compact electrometer are described. This electrometer are battery operated and capable of measuring currents down to the femtoampere level. The portable, high performance nature of the electrometer renders it applicable for deployment in compact instruments for applications such as aerosol particle counters. A parametric experimental study is conducted to determine the role of different components on the performance of the electrometer. Under an ideal configuration, the electrometer has a step-up response time of approximately 3 s. Experiments with the electrometer used for particle counting measurements suggest that the new electrometer has high accuracy and sensitivity in comparison to the Keithley 6514 electrometer. The response of the electrometer used in particle counting studies is consistent with that of an optical single particle counter used in comparison experiments. A damping component introduced to reduce possible spike currents in the electrometer is also seen to reduce noise and almost have no effect on response time. The electrometer response characteristics are presented in detail.     

Identification of differentially expressed proteins in papillary thyroid carcinomas with V600E mutation of BRAF

BRAF, a serine/threonine kinase of the RAF family, is a downstream transducer of the RAS-regulated MAPK pathway. V600E mutation of BRAF protein is the most common genetic alteration occurring in papillary thyroid carcinomas and is prognostic of poor clinicopathological outcomes. Protein expression in the subclass of PTC bearing the BRAF(V600E) mutation was investigated by using 2-DE and MS/MS techniques and compared to that of matched normal thyroid tissues from seven patients. 2-D gel image analysis revealed that the expression of eight polypeptide spots, corresponding to five proteins, were significantly underexpressed in PTC bearing BRAF(V600E) mutation whereas 25 polypeptides, representing 19 distinct proteins, were significantly upregulated in tumour tissue, as compared to normal thyroid. Among the differentially expressed polypeptides, mitochondrial proteins, ROS-scavenger enzymes, apoptosis-related proteins as well as proteins involved in tumour cell proliferation were identified. Although dissimilarities between the present results and those previously reported can be ascribed to the use of different 2-DE techniques, the possibility that BRAF(V600E) mutation is responsible for changes in protein expression distinct from those induced by other oncogenes cannot be ruled out.