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© 2009 Elsevier B.V. The authors gratefully acknowledge the financial support of the Spanish Ministry of Science and Education (MEC) (Project FIS2006-05323) and the UCM-BSCH (Project GR58/08, UCM group 910336). M. Essalhi is thankful to the Middle East Desalination Research Centre for the grant (MEDRC 06-AS007)., Poly(vinylidene fluoride-hexafluoropropylene), PVDF-HFP, hollow fiber membranes were prepared by the dry/wet spinning technique using different copolymer concentrations in the dope solutions ranging from 17 to 24 wt.%. All the spinning parameters were maintained constant except the copolymer concentration. The morphological properties of the hollow fiber membranes were studied in terms of scanning electron microscopy (SEM), atomic force microscopy (AFM) and void volume fraction. The effects of PVDF-HFP content in the spinning solutions were also studied by measuring the water entry pressure and direct contact membrane distillation (DCMD) permeate flux of the hollow fiber membranes. An increase in the copolymer concentration of the spinning solution resulted in a decrease in the precipitation rate and a transition of the cross-section structure from a finger-type structure to a sponge-type structure. Pore size, nodule size and roughness parameters of both the internal and external hollow fiber surfaces were determined by AFM. It was observed that the pore size decreased in both the internal and external surfaces of the hollow fiber membranes with increasing the copolymer concentration and reached a minimum value at the outer surface for PVDF-HFP concentrations greater than 20 wt.%. Water entry pressure values were decreased whereas both the void volume fraction and the DCMD permeate flux increased with decreasing the copolymer concentration., Spanish Ministry of Science and Education (MEC), UCM-BSCH, Middle East Desalination Research Centre (MEDRC), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The Minerals, Metals & Materials Society and ASM International 2010. Financial support from CICYT (Project Nos. MAT2003-01172 and MAT2006-11202) is gratefully acknowledged. Two of the authors, PH and CMC, thank CSIC for an I3P fellowship and an I3P contract, respectively. We also thank A. García-Delgado for assistance with electron microscopy and C.C. Moreno-Hernández and J.A. Jiménez- Rodríguez for assistance with X-ray diffraction. Finally, the authors make a special mention in memory of P.J. González-Aparicio for his assistance with electron microscopy during all these years., The 7075 alloy is an Al-Zn-Mg-Cu wrought age-hardenable aluminum alloy widely used in the aeronautical industry. The alloy was accumulative roll bonded at 300 A degrees C (573 K), 350 A degrees C (623 K), and 400 A degrees C (673 K), and the microstructure, texture, and hardness were investigated. Cell/(sub)grain size in the nanostructured range, typical beta-fiber rolling texture, and homogeneous hardness through thickness were determined in all cases. Misorientation was different at each processing temperature. At 400 A degrees C, the presence of elements in solid solution and the partial dissolution of the hardening precipitates lead to a poorly misoriented microstructure with a high dislocation density and a homogeneous beta-fiber texture of low intensity, typical of intermediate degrees of rolling. At 350 A degrees C and 300 A degrees C, highly misoriented microstructures with smaller dislocation density and intense heterogeneous beta-fiber rolling texture are observed, especially at 350 A degrees C, wherein the degree of dynamic recovery (DRV) is higher. Hardness of the accumulative roll bonded samples is smaller than that of the starting material due to particle coarsening, and it is affected by solid solution and/or by fine precipitates produced by reprecipitation of the elements in solid solution., CICYT, CSIC, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2008 The American Physical Society. The authors acknowledge financial support from the Comunidad de Madrid Project No. CAM-S-0505/PPQ/0316, from Santander-UCM Project No.PR27/05-13926, and from the Spanish Ministerio de Educación y Ciencia Project No. MAT2006-13149-C02-01., Titanium dioxide rutile crystals have been nanoindented and studied by a combination of atomic force microscopy imaging and analysis of force vs penetration curves. In all the experiments, gold crystals have been used as a reference. A concept of nanoindentation effective volume is introduced to differentiate the bulk behavior from that of a small defect-free volume around the indentation. In the latter volume, a reversible Hertzian elastic stage is identified with a Young modulus comparable to that of the bulk. At higher loads, an incipient plastic range is recognized in which the load is linear on the penetration and permanent traces are left behind at the surface upon tip retraction. In that range, the hardness is constant, about five times smaller than the yield strength and more than three times smaller than the corresponding bulk value. This reduced hardness is explained in terms of the operation of dislocation sources with a low-energy barrier., Comunidad de Madrid, Santander-UCM, Spanish Ministerio de Educacion y Ciencia, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

While the bulk of the high-entropy alloys is widely studied and characterized by their configurational entropy, there is a lack of general information regarding the configurational entropy of the grain boundaries. Here, we derived for the first time the basic relationships of this thermodynamic quantity related to the solute segregation at grain boundaries. Some examples of the appearance of the grain boundary configurational entropy are shown, and its effect on intergranular properties is discussed. It is stated that the role of grain boundary configurational entropy in interfacial properties is not completely clear and represents a challenge for future research.

Epidermal growth factor (EGF) is required for various regulations of skin tissue including wound healing; however, it has limited stability due to the physicochemical conditions of the wound milieu. The lack of functional EGF within the wound can cause permanent tissue defects and therefore, current wound patch designs involve EGF-releasing components. Consequently, the focus of such systems is to improve the wound healing mechanism, with minimal attention on melanogenesis of the scar tissue. The present study investigates in vitro/in vivo wound healing and melanogenesis potential of the EGF-doped films comprised of arrays of chitosan:gelatin nanopillars (nano C:G films) prepared by using nanoporous anodic alumina molds. The potential of EGF-doped films in wound healing was examined with individual and coculture systems of fibroblasts and melanocytes to mimic the wound conditions. The outcomes demonstrated that compared to the control groups, the combination of EGF doping and nanotopography consistently provided the highest levels of melanogenic activity-related genes, melanin contents as well as EGFR expressions for both melanocyte-only and coculture setups. Proteomic, genomic and histological analysis of the excisional wound model further demonstrated that if EGF was present within the nanostructured films, the performance of these substrates in terms of wound closure, collagen thickness as well as melanin deposition was considerably improved. Furthermore, when compared with the control saline treatment and healthy mice groups, significant differences for such parameters were obtained for the nano C:G films, irrespective of their EGF contents. Overall, the results indicate that EGF-doped nano C:G films are good candidates as wound patches that not only provide desirable healing characteristics but also cause improved melanogenic outputs., Scientific and Technological Research Council of Turkey TUBITAK BIDEB 2214-A Program; [1059B141601323], S. A. would like to thank grants from the Scientific and Technological Research Council of Turkey TUBITAK BIDEB 2214-A Program (no. 1059B141601323).

In this study, an efficient fatigue life estimation approach is proposed based on an equivalent solid model, along with two stress concentration factors, instead of a lattice model to simplify simulations for the strain-life method. One of the stress concentration factors accounts for the stress concentrations at the strut joints in lattice structures without any manufacturing effect, while the other accounts for the stress concentrations due to surface defects on the struts introduced by the additive manufacturing process. A simple solid cell, for which the dimensions are the same as those of the lattice cell, is first used to estimate the fatigue life of the bulk material used in the additive manufacturing process using the Brown-Miller strain-life method. Combinations of two stress concentration factors were then utilized to predict the fatigue life of the lattice structure from the equivalent solid model. Using this approach, computationally expensive lattice structure simulations were eliminated, and the fatigue life of the lattice structure was predicted directly from the bulk material fatigue life estimation. The proposed approach was applied to different lattice types made of Ti-6Al-4V alloy using the laser-powder bed fusion additive manufacturing process. The fatigue life results estimated using the proposed approach were in good agreement with the experimental fatigue life results reported in the literature.

Article; Early Access, This study aims to investigate the energy absorption performance of three bending-dominated lattice structures including quad-diametral (QD), quad-diametral-line (QDL), and dodecahedron (DO)). Compression test specimens with these three lattice types were manufactured using the material extrusion additive manufacturing technique with PLA material. The specimens were manufactured with different sets of values of the print temperature, layer thickness, and line width to identify their effect on the energy absorption performance. Taguchi's method was utilized for this purpose which revealed that the temperature is the most effective and its optimized value is 225 ; DEG;C. It was also found that the energy absorption performance of the DO lattice is superior to that of QD and QDL lattices. In the following set of experiments, the print temperature was fixed to its optimized value (i.e. 225 ; DEG;C), and another process parameter (i.e. print speed) along with layer thickness and line width were investigated among eight different groups of DO lattices. Numerical investigations were also performed and validated based on the experimental results. Parametric studies were also done for the DO lattice to improve its energy absorption performance by changing the strut diameters and introducing grading to the struts at each lattice cell., Scientific and Technological Research Council of Turkiye; [122M823], This research was funded by a grant from The Scientific and Technological Research Council of Turkiye, project number 122M823.

Additive manufacturing (AM) technology is used in sectors such as automotive and aerospace, due to its advantages in producing complex and lightweight structures. However, it is necessary to reduce the total manufacturing costs for AM technology to become widespread. The topology optimization (TO) studies in the literature typically optimize only the design without taking into account the manufacturing phase or sequentially optimize the topology first and then the process parameters. On the other hand, simultaneous optimization of topology together with process parameters provides more efficient and less costly solutions. This paper describes a strategy for simultaneous optimization of topology along with process parameters of the laser-powder bed fusion (L-PBF) process. The topology, laser power, scanning speed, energy density, and yield strength are controlled by integrating the overall process-property-structure-performance relationship of the L-PBF process into the optimization. The proposed simultaneous optimization method aims to minimize the total cost function including material, manufacturing, and energy costs. Moreover, the constraint functions of the optimization include the volume fraction, the strength of the structure, and the energy density calculated according to the process parameters. The proposed method is successfully applied to three different design problems as cantilever beam, MBB beam, and L bracket, respectively. The results of different TO methods including conventional TO (compliance minimization), structural TO (similar to stress-constrained TO), and sequential process parameters and topology optimization are compared with the results of the proposed method. It is found that the proposed method provided the minimum cost results, and the obtained designs met the structural requirements., Scientific and Technological Research Council of Turkey (TUEBITAK) [5189901], This study is a part of the project (# 5189901) supported by The Scientific and Technological Research Council of Turkey (TUEBITAK) under the Frontier R ; amp;D Laboratory Support Program and performed in Turkish Aerospace Industries Inc. The funding provided by TUEBITAK under Grant No. 5189901 is gratefully acknowledged.

Background: Peritendinous injection of local anesthetics, alone or in combination with corticosteroids, is widely used in the treatment of tendinopathies. Toxicity of local anesthetics has been demonstrated in many cells, including myocytes, chondrocytes, and neurons. Bupivacaine and lidocaine are known to have time- and dose-dependent cytotoxicity in these cells. The effects of these agents on the tendon remain unknown. Purpose: To show histological and biomechanical effects after the injection of different local anesthetics and steroids, both single and combined, at different concentrations into the peritendinous sheath of rat Achilles tendon. Study Design: Controlled laboratory study. Methods: In the study, 100 rats were divided into 10 groups with equal body weights. Inflammation was induced in both Achilles tendons of each rat by means of the ball drop technique; 7 hours later, injections were made into the peritendinous sheaths of both Achilles tendons using lidocaine, bupivacaine, and dexamethasone as appropriate for the rat's group. At the end of the first week, the right Achilles tendons of the rats were removed for histological study. Left Achilles tendons were evaluated in terms of biomechanics. Results: Histological findings demonstrated that the group with the most toxicity to the tendon was the group that received injection of dexamethasone alone. The groups with the least toxicity were those receiving dexamethasone combined with low- or high-dose bupivacaine. Biomechanical findings showed that the experimental groups had similar results to each other with the exception of the groups receiving 0.25% bupivacaine alone and dexamethasone alone, in which tendons revealed higher tensile strength. Conclusion: Local anesthetic and steroid applications have different histological and biomechanical effects on the tendon. Although the dexamethasone-injected group was the most affected in terms of histology, these changes could not be demonstrated biomechanically

The build plate location and post-processing effects on the properties of Ti-6Al-4V alloys fabricated via electron beam melting (EBM) are investigated in the context of spatial variability. Tensile test specimens are fabricated in four corner and center locations of the EBM machine build plate with three different dimensions. One specimen has standard dimensions of 6 mm gauge length diameter; the second one has 25% higher diameters, called the offset specimens, and the third is a cylinder with a diameter of 15 mm, called the block specimens. The standard specimen dimensions are obtained by applying machining to the block and offset specimens to evaluate the influence of the larger dimension and post-processing on the mechanical properties, including spatial variability. The yield strength, tensile strength, and ductility are obtained by performing tensile tests. The density and surface roughness of the specimens are measured before and after machining. Correlation plots and semivariograms are used to examine the effect of spatial variability on the properties of the fabricated specimens at different build plate locations. The densities of the block, offset, and standard specimens are 99.4%, 98.6%, and 98.8%, respectively. The surface roughness (Ra) values reduced from 29.5 to 0.7 mu m after machining the block specimens, while the roughness is as high as 47.2 mu m for the standard specimens. Following the machining process, the yield strength increases from 970 MPa for the standard specimens to 1039 MPa for the block specimens. The tensile strengths are approximately 1115 MPa and 1074 MPa for the block and offset specimens, respectively, whereas for the standard specimens, it is as low as 996 MPa. Similarly, the ductility increases to 13.8% when the block specimens are machined compared to the standard specimen result of 5.4%. For the standard specimens, approximately 5% change in the parameters could be observed at different build plate locations. The location depe, Presidency of Defense Industries; Turkish Aerospace under the SAYP project [DDKIT1], This work was supported by Presidency of Defense Industries and the Turkish Aerospace under the SAYP project DDKIT1.

Epidermal growth factor (EGF) is required for various regulations of skin tissue including wound healing; however, it has limited stability due to the physicochemical conditions of the wound milieu. The lack of functional EGF within the wound can cause permanent tissue defects and therefore, current wound patch designs involve EGF-releasing components. Consequently, the focus of such systems is to improve the wound healing mechanism, with minimal attention on melanogenesis of the scar tissue. The present study investigates in vitro/in vivo wound healing and melanogenesis potential of the EGF-doped films comprised of arrays of chitosan:gelatin nanopillars (nano C:G films) prepared by using nanoporous anodic alumina molds. The potential of EGF-doped films in wound healing was examined with individual and coculture systems of fibroblasts and melanocytes to mimic the wound conditions. The outcomes demonstrated that compared to the control groups, the combination of EGF doping and nanotopography consistently provided the highest levels of melanogenic activity-related genes, melanin contents as well as EGFR expressions for both melanocyte-only and coculture setups. Proteomic, genomic and histological analysis of the excisional wound model further demonstrated that if EGF was present within the nanostructured films, the performance of these substrates in terms of wound closure, collagen thickness as well as melanin deposition was considerably improved. Furthermore, when compared with the control saline treatment and healthy mice groups, significant differences for such parameters were obtained for the nano C:G films, irrespective of their EGF contents. Overall, the results indicate that EGF-doped nano C:G films are good candidates as wound patches that not only provide desirable healing characteristics but also cause improved melanogenic outputs., Scientific and Technological Research Council of Turkey TUBITAK BIDEB 2214-A Program; [1059B141601323], S. A. would like to thank grants from the Scientific and Technological Research Council of Turkey TUBITAK BIDEB 2214-A Program (no. 1059B141601323).

The build plate location and post-processing effects on the properties of Ti-6Al-4V alloys fabricated via electron beam melting (EBM) are investigated in the context of spatial variability. Tensile test specimens are fabricated in four corner and center locations of the EBM machine build plate with three different dimensions. One specimen has standard dimensions of 6 mm gauge length diameter; the second one has 25% higher diameters, called the offset specimens, and the third is a cylinder with a diameter of 15 mm, called the block specimens. The standard specimen dimensions are obtained by applying machining to the block and offset specimens to evaluate the influence of the larger dimension and post-processing on the mechanical properties, including spatial variability. The yield strength, tensile strength, and ductility are obtained by performing tensile tests. The density and surface roughness of the specimens are measured before and after machining. Correlation plots and semivariograms are used to examine the effect of spatial variability on the properties of the fabricated specimens at different build plate locations. The densities of the block, offset, and standard specimens are 99.4%, 98.6%, and 98.8%, respectively. The surface roughness (Ra) values reduced from 29.5 to 0.7 mu m after machining the block specimens, while the roughness is as high as 47.2 mu m for the standard specimens. Following the machining process, the yield strength increases from 970 MPa for the standard specimens to 1039 MPa for the block specimens. The tensile strengths are approximately 1115 MPa and 1074 MPa for the block and offset specimens, respectively, whereas for the standard specimens, it is as low as 996 MPa. Similarly, the ductility increases to 13.8% when the block specimens are machined compared to the standard specimen result of 5.4%. For the standard specimens, approximately 5% change in the parameters could be observed at different build plate locations. The location depe, Presidency of Defense Industries; Turkish Aerospace under the SAYP project [DDKIT1], This work was supported by Presidency of Defense Industries and the Turkish Aerospace under the SAYP project DDKIT1.

An insect's living systems-circulation, respiration, and a branching nervous system-extend from the body into the wing. Wing hemolymph circulation is critical for hydrating tissues and supplying nutrients to living systems such as sensory organs across the wing. Despite the critical role of hemolymph circulation in maintaining healthy wing function, wings are often considered "lifeless" cuticle, and flows remain largely unquantified. High-speed fluorescent microscopy and particle tracking of hemolymph in the wings and body of the grasshopper Schistocerca americana revealed dynamic flow in every vein of the fore- and hindwings. The global system forms a circuit, but local flow behavior is complex, exhibiting three distinct types: pulsatile, aperiodic, and "leaky" flow. Thoracic wing hearts pull hemolymph from the wing at slower frequencies than the dorsal vessel; however, the velocity of returning hemolymph (in the hindwing) is faster than in that of the dorsal vessel. To characterize the wing's internal flow mechanics, we mapped dimensionless flow parameters across the wings, revealing viscous flow regimes. Wings sustain ecologically important insect behaviors such as pollination and migration. Analysis of the wing circulatory system provides a template for future studies investigating the critical hemodynamics necessary to sustaining wing health and insect flight. Study of grasshopper wings shows that hemolymph flows through every vein in the insect wing, creating a broad circuitous flow pattern in the wings, with three different flow behaviours (pulsatile, leaky, aperiodic).

The global production of coconut, mainly for food and oil production, exceeds 62 million tonnes per annum. Large quantities of coconut husk remain unutilized after industrial processing, giving rise to environmental problems. This fails to exploit the potential presented by the extraction of coir, which could have numerous applications. Traditional products such as textiles, mats, and brushes made from coir are increasingly being joined by new, high-value, non-traditional uses. This review article summarizes new fields of application for coir as reinforcing fibers in binderless fiberboards, natural fiber composites, construction materials, solid biofuels, and an absorbent for heavy metals and toxic materials. The use of coir in these new fields will reduce waste and increase sustainability.

The superior biocompatibility and biodegradability of polyhydroxyalkanoates (PHAs) compared to man-made biopolymers such as polylactic acid promise huge potential in biomedical applications, especially tissue engineering (TE). Textile fiber-based TE scaffolds offer unique opportunities to imitate the anisotropic, hierarchical, or strain-stiffening properties of native tissues. A combination of PHAs' enhanced biocompatibility and fiber-based TE scaffolds could improve the performance of TE scaffolds. However, the PHAs' complex crystallization behavior and the resulting intricate spinning procedures remain a challenge. This review focuses on discussing the developments in PHA melt and wet spinning, their challenges, process parameters, and fiber characteristics while revealing the lack of an in-depth fiber characterization of wet-spun fibers compared to melt-spun filaments, leading to squandered potential in scaffold development. Additionally, the biomedical application of PHAs other than poly-4-hydroxybutyrate is hampered by a failure of polymer purity to meet the requirements for biomedical applications.

This study presents an unexplored method to produce formaldehyde-free MDF. Steam exploded Arundo donax L. (STEX-AD) and untreated wood fibers (WF) were mixed at different mixing rates (0/100, 50/50, and 100/0, respectively) and two series of boards were manufactured, with 4 wt% of pMDI, based on dry fibers, and self-bonded. The mechanical and physical performance of the boards was analyzed as a function of the adhesive content and the density. The mechanical performance and dimensional stability were determined by following European standards. The material formulation and the density of the boards had a significant effect on both mechanical and physical properties. The boards made solely of STEX-AD were comparable to those made with pMDI, while the panels made of WF without adhesive were those that performed the worst. The STEX-AD showed the ability to reduce the TS for both pMDI-bonded and self-bonded boards, although leading to a high WA and a higher short-term absorption for the latter. The results presented show the feasibility of using STEX-AD in the manufacturing of self-bonded MDF and the improvement of dimensional stability. Nonetheless, further studies are needed especially to address the enhancement of the internal bond (IB).

The concern for the amount of end-of-life tires generated each year has arisen from constant research directed to their valorisation. Herein we propose a new material, which is constituted by GTR with a binder, as acoustic and also as a thermal insulator for civil engineering. The insulator can also include the fibre mat present in the tire, seldomly considered as a recyclable sub-product. To provide insight into the insulating behaviour of these materials, four mathematical models have been tested and compared with the experimental results of thermal conductivity. The Lewis-Nielsen modelization presented good accuracy with deviations of less than 3%. A statistical analysis has also been conducted on the experimental data showing that the parameter with more effect on thermal conductivity is thickness (differences up to 43%) being particle size, less important (ca 6%). In acoustic properties, different effects can be observed depending on the frequency range, being the density the most relevant. From the mathematical, statistical and experimental analysis can be deduced that good insulation properties would be achieved in materials with: low density, porous; including mat and thick. The effect of these parameters causes variations of thermal conductivity from 0.189 to 0.117 W/m·K and in sound absorption coefficient from 0.06 to 0.6.

Traditional methods for designing concrete mixtures provide good results; however, they do not guarantee the optimum composition. Consequently, applying operational research techniques is motivated by an increasing need for designers to proportion the concrete's raw materials that satisfy the concrete performance requirements such as mechanical properties, chemical properties, workability, sustainability, and cost. For this reason, many authors have been looking for mathematical programming and machine learning solutions to predict concrete mix properties and optimise concrete mixtures. Therefore, a comprehensive review of operational research techniques concerning the design and proportioning of concrete mixtures and a classification framework are presented herein.