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Composite materials fabricated via additive manufacturing are becoming more relevant in ready-for use products used in engineering applications like aerospace structures, propellers, electric vehicles, or sandwich cores. Continuous Fiber Reinforced Polymeric (CFRP) composites are 3D-printed composites with tailor-made properties due to the capability of the printing process to deposit matrix and fiber whenever required. However, CFRP products behave differently and have lower mechanical properties than traditional composites. This study aimed to analyze the impact strength of CFRP specimens with gyroid infill and the effects of two build (flat and on-edge) and two raster (0° and 45°) orientations on impact behavior. The gyroid infill helps to obtain a light-weight structure and it has been used in energy absorption applications showing excellent mechanical behavior in thermoplastic 3D-products. The specimens were manufactured using Onyx as the matrix and aramid fiber as the reinforcement materials. The impact energy absorption of CFRP composites was measured using unnotched Izod impact specimens. The impact tests results were statistically analyzed, revealing that the build orientation directly and significantly affects the impact behavior, resulting in higher impact absorption when flat orientation is used to produce CFRP composites. The impact strength of CFRP composites increased 8 times, and 2 times for flat and on-edge oriented specimens, respectively compared to pure Onyx specimens. The variation in impact energy absorption between raster orientations in both build orientations was not significant, the difference in flat-oriented specimens at 0° and 45° was only 0.2 J, and between on-edge-oriented specimens at 0° and 45° was only 0.089 J. Also, the after impact specimens were analyzed to categorize the different failure modes observed. The after-impact analysis showed poor impregnation between aramid and onyx layers, causing delamination, fiber bridging, and fiber exposure failures. The combination of Aramid, Onyx, and a non-solid infill (gyroid) demonstrated positive results in impact behavior, obtaining high-impact absorption (165 kJ/m2) with no more than 56 % of fiver volume. The impact properties information of CFRP composites made with aramid fibers is still very scarce, joined to the lack of information on the impact properties of CFRP composites with non-solid infill, like gyroids or sinusoidal path infills. The results of this research open the possibility of using non-solid infill in CFR process that can be used to manufacture and test ready-for-use CFRP products in tasks that require high-strength, low-weight structures and impact energy absorption.

The anisotropic plasticity constants of the CPB06 criterion for Ti64, previously identified with experiments performed in all three dimensions, are applied here to evaluate the effect of the direct and inverse calibration strategies of the tensile-compression asymmetry parameter k on the predictive behavior of large deformations of the hexagonal close-packed (hcp) alloy. The direct calibration strategy is based on model fitting with experimental strain hardening data up to the onset of plastic instability. The inverse calibration strategy reduces prediction errors of the load-displacement curves of both the cylindrical bar tensile and the elliptical cylinder compression tests. The results provide interesting insights into the identification of the laws modeling large deformations of hcp materials.

The manufacturing processes and design of metal and alloy products can be performed over a wide range of strain rates and temperatures. To design and optimize these processes using computational mechanics tools, the selection and calibration of the constitutive models is critical. In the case of hazardous and explosive impact loads, it is not always possible to test material properties. For this purpose, this paper assesses the efficiency and the accuracy of different architectures of ANNs for the identification of the Johnson-Cook material model parameters. The implemented computational tool of an ANN-based parameter identification strategy provides adequate results in a range of strain rates required for general manufacturing and product design applications. Four ANN architectures are studied to find the most suitable configuration for a reduced amount of experimental data, particularly for cases where high-impact testing is constrained. The different ANN structures are evaluated based on the model's predictive capability, revealing that the perceptron-based network of 66 inputs and one hidden layer of 30 neurons provides the highest prediction accuracy of the effective flow stress-strain behavior of Ti64 alloy and three virtual materials.

The use of computational tools for the development of technologies in fields such as medicine and engineering has facilitated the process of designing new components and devices for these areas. In this work, two proposals focused on a hollow microneedle array (MNA) for the administration of an analgesic drug are shown and evaluated by means of a computational fluid dynamics (CFD) simulation distributed in three stages. In the first stage, the behavior of lidocaine through the MNA was evaluated as a workflow. Then, the possible entry of the drug into the organism, which was established as a porous aqueous medium, was modeled. Finally, a joint simulation was performed to understand the general behavior in the interaction between the outflow of an MNA and the body to which lidocaine is administered. The input parameters to the simulation were set at a velocity of 0.05 m∙s -1 , at a pressure of 2000 Pa, the dominant behavior was defined as laminar flow, and a resistive pressure at the inlet of 400 Pa. Our results indicate that the vertical flow exhibits a better fluid distribution across the MNAs and favorable infiltration behavior, representing better delivery of the analgesic to the skin capillaries.

In this research, a three-dimensional auxetic configuration based on a known re-entrant cell is proposed. The 3D auxetic cell is configured from a new design parameter that produces an internal rotation angle to its re-entrant elements to study elastic properties in its three orthogonal directions. Through a topological analysis using Timoshenko beam theory, the bending of its re-entrant struts is modeled as a function of the new design parameter to manipulate Poisson's ratio and Young's modulus. Experimental samples were fabricated using a fused filament fabrication system using ABS and subsequently tested under quasi-static compression and bending tests. Additionally, an orthotropy factor is applied that allows for measuring the deviation between the mechanical properties of each structure. The experimental results validate the theoretical design and show that this new unit cell can transmit an orthotropic mechanical behavior to the macrostructure. In addition, the proposed structure can provide a different bending stiffness behavior in up to three working directions, which allows the application under different conditions of external forces, such as a prosthetic ankle.

A three-dimensional auxetic structure based on a known planar configuration including a design parameter producing asymmetry is proposed in this study. The auxetic cell is designed by topology analysis using classical Timoshenko beam theory in order to obtain the required orthotropic elastic properties. Samples of the structure are fabricated using the ABSplus fused filament technique and subsequently tested under quasi-static compression to statistically determine the Poisson's ratio and Young's modulus. The experimental results show good agreement with the topological analysis and reveal that the proposed structure can adequately provide different elastic properties in its three orthogonal directions. In addition, three point bending tests were carried out to determine the mechanical behavior of this cellular structure. The results show that this auxetic cell influences the macrostructure to exhibit different stiffness behavior in three working directions.

This paper is focused on mode I delimitation of a unidirectional glass fibre reinforced polymer (GFRP) composite. The aim is to propose an accurate and simple characterisation of three cohesive zone models (CZM)-bilinear, trilinear, and potential-from the measurement of the load-displacement curve during a double cantilever beam experimental test. For that, a framework based on the equivalent linear elastic fracture mechanics (LEFM) R-curve is here proposed, which has never before been developed for a bilinear and a potential CZM. Besides, in order to validate this strategy, an optimisation algorithm for solving an inverse problem is also implemented. It is shown that the parameters' identification using the equivalent LEFM R-curve enables the same accuracy but reduces 72% the numerical efforts respect to a "blind fitting" (i.e., the optimisation algorithm). Therefore, even if optimisation techniques become popular at present due to their easy numerical implementation, strategies founded on physical models are still better solutions especially when evaluating the objective function is expensive as in mechanical problems.

Recent catastrophes that occurred during seismic events suggest the importance of developing new seismic-resistant materials for use in building construction. Ordinary concrete is one of the most common materials in buildings. However, due to its low ductility and flexural strength, its seismic behavior can be improved upon by different additives. In this regard, wood-concrete composites exhibit desirable structural properties not achievable by either wood or concrete alone, making it an interesting material from a seismic point of view. This work analyzes and compares the performance of blocks built with ordinary concrete versus blocks built using different wood additives (sawdust and wood shavings). This includes the construction of concrete blocks in a lab, determination of their construction and seismic-resistant properties, as well as an analysis of their performance in buildings with a different number of storeys. The results show how blocks with wood aggregates comply with current regulations for structural materials in a seismic country like Chile, while also considerably outperforming traditional concrete blocks in the event of an earthquake.

Isolation and characterization of auxotrophic mutants from wild-type and astaxanthin mutant strains of Phaffia rhodozyma is described. Differences in survival were observed when u.v. irradiation of P. rhodozyma wild-type and astaxanthin mutant strains were incubated in the dark or exposed to photoreactivating light. Ultra-violet mutagenesis was not effective to produce auxotrophic mutants in this yeast. Auxotrophic mutants were obtained with high efficiency through a nystatin enrichment procedure after a N-methyl-N'-nitro-N-nitrosoguanidine (NGT) mutagenic treatment with a 0.12% survivor level. Stringent mutagenetic conditions were needed to obtain P. rhodozyma auxotrophs. The most frequent mutants were ade- and met- in a rather narrow auxotroph spectrum. These results may be associated with a possible diploid condition of this yeast. The high number of adenine auxotrophs obtained in relation to other auxotrophic mutants suggests the possibility of some degree of heterozygosity in the wild-type strain UCD 67-385.

Stable red astaxanthin-producing transformants were obtained after genetic transformation of two Phaffia rhodozyma mutants. A yellow mutant, accumulating beta-carotene, and an albino mutant, accumulating phytoene, from P. rhodozyma were transformed using a genomic library of wild-type strain UCD 67-385 in the pBluescript vector. Hybridization assays, using the pBluescript DNA as a radioactive probe, indicate integration of vector sequences into the genome of the transformants. Transformants DNA was digested with restriction endonucleases, ligated with T4 DNA ligase and then used to transform E. coli. Ampicillin resistant plasmids, containing 0.1, 0.2, and 2.5 kb DNA inserts of P. rhodozyma, were rescued from the yeast red transformants. The molecular analysis indicate that transformation has occurred by an integration event of donor DNA into the genome of the host strains.

In this work we establish the chromosomal composition of a wild-type, one astaxanthin and two beta-carotene overproducer strains of the red yeast Phaffia rhodozyma. The method used has been pulsed field gel electrophoresis, which has determined 9 DNA chromosomal bands in the yeast genome. The two largest bands are triplets and two other bands, VI and VIII, seem to be doublets. The size of the chromosomal bands varies between 0.35 and 2.5 Mb, suggesting a genome size of 25 Mb. The technique used, complemented with hybridization assays using specific DNA probes, provides direct information about the genomic organization of P. rhodozyma. We have also cloned and located in chromosomal bands different DNA sequences that code for the translation elongation factor 1 alpha (ef-1 alpha), a 7.6 kb BamHI fragment of repetitive DNA (possibly rDNA) and a randomly chosen fragment (named locus R2). Additionally, we have detected a chromosomal length polymorphism between wild-type strains and mutant strains affecting carotenogenesis obtained in our laboratory.

The carbohydrate portion of fraction I of the Neurospora crassa cell wall has been analyzed for sugar composition by gas-liquid chromatography and colorimetric methods. The analysis was performed comparatively in a wild-type strain (RL 3-8A) and three morphological mutants: scumbo (FGSC 49), peak-2a (a mutant known to be allelic to biscuit), and ragged (FGSC 296). Fraction I of all strains studied contains glucose, mannose, and galactose as the main sugars. Uronic acids and amino sugars are also present in small amounts. The glycosidic linkages binding the neutral sugars were analyzed by Lindberg's combined gas chromatography-mass spectrometry techniques for identification of the partially methylated alditol acitate sugar derivatives. The main polymeric portion of fraction I seems to be a linear glucan with the glucose residues linked by 1 leads to 3 and 1 leads to 4 bonds. A mannan portion with a branched configuration is also present, with galactose as the sugar residue which serves as branches in the molecule(s). The branched mannan portion appears to increase in amount in correlation with more drastic morphological changes of the mycelia. In this respect, the mutant ragged has the lowest mycelial growth rate and the largest amount of mannan. The importance of the polysaccharide structure of fraction I on the colonial morphology of the mycelia is discussed.

A plasmid (named pCN2) carrying a 7.6 kb BamHI DNA insert was isolated from a Neurospora crassa genomic library raised in the yeast vector YRp7. Saccharomyces cerevisiae suco and N. crassa inv strains transformed with pNC2 were able to grow on sucrose-based media and expressed invertase activity. Saccharomyces cerevisiae suco (pNC2) expressed a product which immunoreacted with antibody raised against purified invertase from wild type N. crassa, although S. cerevisiae suc+ did not. The cloned DNA hybridized with a 7.6 kb DNA fragment from BamHI-restricted wild type N. crassa DNA. Plasmid pNC2 transformed N. crassa Inv- to Inv+ by integration either near to the endogenous inv locus (40% events) or at other genomic sites (60% events). It appears therefore that the cloned DNA piece encodes the N. crassa invertase enzyme. A 3.8 kb XhoI DNA fragment, derived from pNC2, inserted in YRp7, in both orientation, was able to express invertase activity in yeast, suggesting that it contains an intact invertase gene which is not expressed from a vector promoter.

The heteropolysaccharide present in fraction 1 of the Neurospora crassa cell wall has been characterized in wild-type and morphological mutant strains of this fungus. Single and double mutations have been studied to determine possible genetic interactions controlling the chemical composition of such heteropolysaccharides . Single mutations studied were peak-2, scumbo ( FGSC 49), ragged ( FGSC 296), and crisp -1 ( FGSC 488). Double mutations studied were peak-2, scumbo ( FGSC 419), and ragged crisp -1. In all these strains, the main constituents of the heteropolysaccharide were glucose, mannose and galactose. Glycosidic linkages binding these neutral sugars have been identified by gas-liquid chromatography. A chemical structure of fraction I heteropolysaccharide is proposed. The results obtained with double mutants suggest the existence of genetic interactions, such as complementation or additive effects of lesions of different genes, to control the chemical composition and structure of the cell wall and the morphology of N. crassa mycelium.

D-Arabinose dehydrogenase has been purified to homogeneity from wild-type Neurospora crassa 74-A (FGSC 262) and from two colonial mutants, col-15a (FGSC 1391) and col-16a (FGSC 1349), found to contain more of the enzyme. The enzymes were characterized by measurement of several kinetic and physicochemical parameters. The enzymes were the same in all characteristics studied thus far. Immunological studied performed with enzyme preparations from the three strains showed antigenic identity and indicated that those colonial strains contain more normal enzyme, rather than the usual amount of an altered "improved" enzyme. Quantitation of the enzyme in crude extracts, performed by single radial immunodiffusion, showed that the colonial strains have twice the level of enzyme as the wild-type strain. Genetic characterization, performed by analysis of meiotic products, heterokaryosis, and reversions, indicated that the difference in D-arabinose dehydrogenase activity detected among the three strains is probably determined by one gene. The genetic control, structural or regulatory of this enzyme activity is different from that determining the morphological alterations exhibited by mutant strains carrying the col-15 or col-16 gene.