Computer-aided gene design

A computer program, which runs on MS-DOS personal computers,is described that assists in the design of synthetic genes codingfor proteins. The goal of the program is the design of a genewhich (0 contains as many unique restriction sites as possibleand (ii) uses a specific codon usage. The gene designed accordingto the criteria above is (i) suitable for ‘modular mutagenesis’experiments and (ii) optimized for expression. The program 'reverse-translates'protein sequences into degenerated DNA sequences, generatesa map of potential restriction sites and locates sequence positionswhere unique restriction sites can be accommodated. The nucleicacid sequence is then ‘refined’ according to a specificcodon usage to remove any degeneration. Unique restriction sites,if potentially present, can be ‘forced’ into thedegenerated nucleic acid sequence by using 'priority codes'assigned to different restriction sequences.     

CAMMInA: a mobile ambient information system to motivate elders to exercise

Several strategies have been identified for designing effective persuasive technology that encourages people to adopt healthy lifestyle habits. However, to implement these strategies for motivating elders to exercise, we need to take into account the elders’ particular characteristics, their needs, and the problems they face to exercise. This paper presents the results of a case study conducted to identify the factors that influence elders to maintain a regular exercise routine. These results enabled us to inform the design of an ambient information system, which by requiring minimal attention and cognitive effort from elders, makes them aware of relevant information that motivates them to exercise. To reach this end, the system implements the following strategies for persuading: abstraction, historical information and reflection, triggers for exercising, and positive and playful reinforcement. A system usability evaluation enabled us to validate these strategies for motivating elders.     

Solving complex problems with a bioinspired model

Membrane systems are parallel and bioinspired systems which simulate membranes behavior when processing information. As a part of unconventional computing, P-systems are proven to be effective in solving complex problems.A software technique is presented here that obtain good results when dealing with such problems. The rules application phase is studied and updated accordingly to obtain the desired results. Certain rules are candidate to be eliminated which can make the model improving in terms of time.     

Mechanical Properties of Steel Surfaces Coated with HfN/VN Superlattices

Mechanical and tribological evolution on 4140 steel surfaces coated with hafnium nitride/vanadium nitride [HfN/VN] _n multilayer systems deposited in various bilayer periods (Λ) via magnetron sputtering has been exhaustively studied in this work. The coatings were characterized in terms of structural, chemical, morphological, mechanical, and tribological properties by x-ray diffraction (XRD), x-ray photo electron spectroscopy (XPS), atomic force microscopy, scanning and transmission electron microscopy, nanoindentation, pin-on-disk, and scratch tests. Moreover, the failure mode mechanisms were observed via scanning electron microscopy. The XRD results showed preferential growth in the face-centered cubic (111) crystal structure for [HfN/VN] _n multilayered coatings. The best enhancement of the mechanical behavior was obtained when the bilayer period (Λ) 15 nm (n = 80), yielding the highest hardness (37 GPa), and elastic modulus (351 GPa). The values for the hardness and elastic modulus were 1.48 and 1.32 times greater than the coating with n = 1, respectively, as well the lowest friction coefficient (~0.15) and the highest critical load (72 N). These results indicated significant enhancements in mechanical, tribological, and adhesion properties, compared to HfN/VN multilayered systems with bilayer period (Λ) of 1200 nm (n = 1). This hardness and toughness enhancement in the multilayered coatings could be attributed to the different mechanisms that produce the layer formation with nanometric thickness due to the number of interfaces acting as obstacles for crack deflection and dissipation of crack energy. Due to the emergent characteristics of the synthesized multilayered, the developed adaptive coating could be considered as higher ordered tool machining systems, capable of sustaining extreme operating conditions for industrial applications.     

Corrosion behaviour of a dissimilar joint TIG weld between austenitic AISI 316L and ferritic AISI 444 stainless steels

The AISI 444 stainless steel (SS) has become an option to substitute the AISI 316L SS because of its low cost and satisfactory corrosion resistance. However, the use of AISI 444 alloy tubes in heat exchangers causes the welding of a dissimilar joint. The aim of this study was evaluate the corrosion resistance of the tube-to-tubesheet welded by a TIG process composed of AISI 316L and AISI 444. Preparation of samples was executed through replication of tube-to-tubesheet joints. In order to test the corrosion resistance of the welded joint, the following tests were applied: sensitisation, mass loss from room temperature up to 90 °C and electrochemical corrosion tests in 0.5 mol/L HCl and 0.5 mol/L H₂SO₄ electrolytes. The results have shown that the dissimilar joint suffers galvanic corrosion with increased degradation of the heat-affected zone of the AISI 444 tube. Nevertheless, the mechanisms of localised corrosion (pit and intergranular) were more active in the AISI 316L alloy. It is concluded that the dissimilar joint showed better corrosion resistance than the welded joint composed solely of AISI 316L at temperatures up to 70 °C, as the conditions observed in this work.     

Antioxidant properties of aminoethylcysteine ketimine decarboxylated dimer: a review

Aminoethylcysteine ketimine decarboxylated dimer is a natural sulfur-containing compound detected in human plasma and urine, in mammalian brain and in many common edible vegetables. Over the past decade many studies have been undertaken to identify its metabolic role. Attention has been focused on its antioxidant properties and on its reactivity against oxygen and nitrogen reactive species. These properties have been studied in different model systems starting from plasma lipoproteins to specific cellular lines. All these studies report that aminoethylcysteine ketimine decarboxylated dimer is able to interact both with reactive oxygen and nitrogen species (hydrogen peroxide, superoxide anion, hydroxyl radical, peroxynitrite and its derivatives). Its antioxidant activity is similar to that of Vitamin E while higher than other hydrophilic antioxidants, such as trolox and N-acetylcysteine.     

Molecular recognition of β-O-GlcNAc glycopeptides by a lectin-like receptor: binding modulation by the underlying Ser or Thr amino acids

The binding properties of different carbohydrates and glycopeptides containing the β-O-2-deoxy-2-(N-acetyl)-D-glucosaminyl (β-O-GlcNAc) to a synthetically prepared lectin-like receptor have been analyzed. The study combines the use of NMR spectroscopy experiments with extensive MD simulations in explicit water. Notably, the presence of a key hydrogen bond between the receptor and the OMe group of the β-O-GlcNAc-OMe derivative appears to be responsible for the high selectivity observed for this compound. In addition, to study the effect on the binding of the underlying amino acid, we have prepared different model glycopeptides, which include the non-natural α-methylserine and α-methylthreonine as underlying amino acids. Interestingly, the presence of a methyl group decreases the affinity constant, especially in those cases in which a β-methyl group is present. As a result, the serine-containing glycopeptide exhibited the highest affinity constant of the glycopeptides, and the threonine derivative showed the lowest one. This low selectivity could have its origin in the difficulty to form both specific hydrogen bonds and hydrophobic (CH-π) contacts.     

Nitrooxyacyl derivatives of salicylic acid: aspirin-like molecules that covalently inactivate cyclooxygenase-1

A recently described series of nitrooxyacyl derivatives of salicylic acid, displaying aspirin‐like anti‐inflammatory and platelet anti‐aggregatory properties, were evaluated for their abilities to inhibit cyclooxygenase (COX). A number of these compounds irreversibly inhibited both COX‐1 and COX‐2 isoforms when tested in isolated human platelets and monocytes. Further studies using COX‐1 expressed in human HEK293T cells showed that this inhibition mechanism is similar to that of aspirin; namely, the products are able to covalently bind to the Ser 530 residue present in the active cleft of the enzyme. Molecular modeling enabled us to rationalize this behavior. Because these products were previously found to display NO‐dependent properties in rat animal models, particularly as they decreased in vivo gastrotoxicity and induced in vitro vasodilation, they represent a new and interesting class of potential aspirin‐like antithrombotic agents worthy of further study.     

Performance assessment of a fixed-bed gasification pilot plant for combined power generation and hydrogen production

Large-scale hydrogen production through near zero emissions gasification plants represents a reliable technology which is being seriously considered for its potential economical implications. However, the application of these technologies is currently subject to high capital and operating costs. This needs great scientific and technical effort to optimize the processes and the equipment, to reduce the hydrogen production cost.In this context, a flexible and fully equipped pilot platform has been built up in the Sotacarbo Research Centre, in order to study several integrated gasification and syngas treatment process configurations for a CO₂-free combined production of hydrogen and electrical energy, to be used in medium and small-scale commercial plants. The platform includes pilot scale fixed-bed up-draft gasifiers, equipped with a flexible and complete syngas treatment line.This paper reports the main results obtained in the pilot plant during the last experimental campaign which has been carried out to improve the plant performance. In particular, a series of experimental tests has been performed in order to optimize the coal gasification process in different operating conditions. Moreover, a mention of the overall plant performance, based on the experimental results, has been presented, with particular reference to hydrogen, carbon and pollutant emissions.     

A multifractal comminution approach for drilling scaling laws

The drilling comminution is theoretically and experimentally analyzed by a multifractal approach. A generalization of the three classical comminution laws [Rittinger, P.R., 1867. Lehrbuch der Aufbereitungskunde. Berlin; Kick, F., 1885. Das Gesetz der Proportionalen Widerstände. Leipzig; Bond, F.C., Min. Eng. 193 (1952) 484] has been performed to evaluate the energy dissipation in the process and to compute the mass distribution of the particles. A transitional fractal exponent of the fragment size distribution is experimentally demonstrated to exist. As a consequence, a multifractal scaling law for the partial mass of fragments and its physical interpretation is consistently proposed.In addition, we show, both theoretically and experimentally, that the drilling strength is strongly size-dependent and cannot be considered a material constant, as classically supposed. Consequently, a multifractal scaling law for the drilling strength is also proposed.