Zinc nutrition in young Chilean adults

To evaluate the effect of dietary factors on plasma zinc levels, dietary zinc intake was estimated and plasma levels were measured in 37 healthy young adults of low and middle socioeconomic status. Our study included 16 males aged 29 +/- 7 and 21 females aged 26 +/- 6 years. Dietary intake of zinc and protein was determined from a 24-hour dietary recall survey. Plasma zinc was measured by atomic absorption spectrophotometry. Alkaline phosphatase (AP) in plasma was also measured and the weight/height percentage for each subject calculated according to Jelliffe's standards. The average diet was composed of cereals, legumes, eggs, bread and noodles, caloric intake was 2051 +/- 154 kcal/day for men and 1767 +/- 158 (x +/- SD) kcal/day for women. The daily intake of zinc was 8.3 +/- 3.0 mg/day for males, and 9.7 +/- 2.0 mg/day for females. Cereals were the main source of zinc for men, while egg and dairy products were for women. Plasma zinc values were 82 +/- 22 micrograms/dl for men and 94 +/- 19 micrograms/dl for women (p less than 0.01). For the whole group plasma zinc concentration was 89 +/- 21 micrograms/dl. Seven males and two females had low plasma zinc values (70 micrograms/dl or less). Alkaline phosphatase (AP) levels were 110 +/- 10 IU for males and 71 +/- 4 IU for females (p less than 0.001). These values did not correlate with the zinc levels. Average weight/height was 99 +/- 18 for men, and 108 +/- 18 for females. Results indicate that on the average, in our study group plasma zinc levels were within the normal range, although they were significantly lower in men. Dietary intake of zinc was below the recommendations, being higher for women as related to values presented by men. The observed low plasma levels of zinc may be caused by a low intake, and/or poor bioavailability.     

Comparative Experimental Studies on Spatial Memory and Learning in Rats and Robots

The study of behavioral and neurophysiological mechanisms involved in rat spatial cognition provides a basis for the development of computational models and robotic experimentation of goal-oriented learning tasks. These models and robotics architectures offer neurobiologists and neuroethologists alternative platforms to study, analyze and predict spatial cognition based behaviors. In this paper we present a comparative analysis of spatial cognition in rats and robots by contrasting similar goal-oriented tasks in a cyclical maze, where studies in rat spatial cognition are used to develop computational system-level models of hippocampus and striatum integrating kinesthetic and visual information to produce a cognitive map of the environment and drive robot experimentation. During training, Hebbian learning and reinforcement learning, in the form of Actor-Critic architecture, enable robots to learn the optimal route leading to a goal from a designated fixed location in the maze. During testing, robots exploit maximum expectations of reward stored within the previously acquired cognitive map to reach the goal from different starting positions. A detailed discussion of comparative experiments in rats and robots is presented contrasting learning latency while characterizing behavioral procedures during navigation such as errors associated with the selection of a non-optimal route, body rotations, normalized length of the traveled path, and hesitations. Additionally, we present results from evaluating neural activity in rats through detection of the immediate early gene Arc to verify the engagement of hippocampus and striatum in information processing while solving the cyclical maze task, such as robots use our corresponding models of those neural structures.     

Multiphoton Lithography as a Promising Tool for Biomedical Applications

Multiphoton lithography (MPL) is a powerful and useful structuring tool capable of generating 2D and 3D arbitrary micro- and nanometer features of various materials with high spatial resolution down to nm-scale. This technology has received tremendous interest in tissue engineering and medical device manufacturing, due to its ability to print sophisticated structures, which is difficult to achieve through traditional printing methods. Thorough consideration of two-photon photoinitiators (PIs) and photoreactive biomaterials is key to the fabrication of such complex 3D micro- and nanostructures. In the current review, different types of two-photon PIs are discussed for their use in biomedical applications. Next, an overview of biomaterials (both natural and synthetic polymers) along with their crosslinking mechanisms is provided. Finally, biomedical applications exploiting MPL are presented, including photocleaving and photopatterning strategies, biomedical devices, tissue engineering, organoids, organ-on-chip, and photodynamic therapy. This review offers a helicopter view on the use of MPL technology in the biomedical field and defines the necessary considerations toward selection or design of PIs and photoreactive biomaterials to serve a multitude of biomedical applications.     

智能蓝光捕捉技术简述

为了防止有害光线对眼部的伤害,依视路集团研发出了智能蓝光捕捉技术,该技术可实现紫外线防护,符合新国标要求的蓝光防护,并维持色彩真实性。     

Dendrochronologically Dated Pine Buildings from Scotland: The SCOT2K Native Pine Dendrochronology Project

The SCOT2K project has extended native pine tree-ring chronology coverage for Scotland to enable reconstruction of past climate and for cultural heritage dating benefits. Using living trees from multiple locations in the Highlands and sub-fossil material from lochs, a network of five regional chronologies has been produced. The project has developed the application of Blue Intensity (BI), a proxy measure for maximum latewood density, which is faster and less costly to obtain than traditional densitometry measurements. The use of both ring-width and BI has been demonstrated to greatly assist historical dendro-dating of pine. This paper presents the dating results for the twenty Scottish pine buildings or sites dendro-dated through the SCOT2K project. They range from the fifteenth to the nineteenth centuries, and from high-status castles to modest cruck cottages. They are mostly located in the Highlands where Scots pine occurs naturally, although an early example of long-distance transport is also identified.     

A study on nanofiber‐reinforced thermoplastic composites (II): Investigation of the mixing rheology and conduction properties

This article is portion of a comprehensive study on the development of nanofiber‐reinforced polymer composites for electrostatic discharge materials and structural composites. Vapor‐grown carbon fibers with an average diameter of 100 nm were used as a precursor and model fiber system for carbon nanotubes. These nanofibers were purified and functionalized to provide for an open network of high‐purity nanofibers. Banbury‐type mixing was used to disperse the nanofibers in the polymer matrix. Rheological and microscopic analysis showed that the high shear processing of the polymer/nanofiber mixture led to a homogeneous dispersion of nanofibers with no agglomerates present and no shortening of the nanofibers. The shear thinning behavior of polymeric materials helps in the mixing of the nanofibers to form the composites. A percolation threshold for electrical conduction of 9–18 wt % was observed for the highly dispersed nanofiber networks. The electrical behavior of these materials was not affected by changes in humidity. Microscopic analysis showed highly dispersed nanofibers with no indications of porosity. These conducting polymers are well suited for electrostatic discharge applications, and might well become multifunctional materials for strength/electrical applications. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1162–1172, 2001     

Improvement in the Pore Size Distribution for Ordered Mesoporous Materials with Cylindrical and Spherical Pores Using the Kelvin Equation

Ordered mesoporous materials such as MCM-41 and SBA-15, which exhibit cylindrical pores open at both ends and SBA-16 with spherical pores, show a strong influence on adsorption and catalytic processes, basically due to their defined pore sizes. In general, the textural characteristics of these materials are obtained by N₂ adsorption?Cdesorption isotherms at 77 K where, for the calculus of the mesopores size, the ??Kelvin equation?? is used. Thus, several authors have conducted studies on the pore size distribution (PSD) for these materials, applying diverse methods such as: Barret, Joyner and Halenda (BJH); Dollimore and Heal (DH); and Kruk, Jaroniec and Sayari (BJH-KJS) methods. To obtain the PSD, the BJH and DH methods were proposed for cylindrical pores, using the desorption branch data of the isotherm, meanwhile the BJH-KJS method uses the adsorption branch data, but assumes the mechanism corresponding to the desorption branch for cylindrical pores. Due to the diversity of methods to evaluate the PSD, all of them with different considerations, it is difficult to determine the most suitable. In this work, with the aim to improve the analysis, the PSD was evaluated from the N₂ adsorption?Cdesorption isotherms at 77 K for a series of materials, MCM-41, SBA-15 and SBA-16 type, synthesized in our laboratory. By a modification in the Kelvin equation with the addition of a correction term (f _c ) and assuming appropriate mechanisms of capillary condensation and capillary evaporation, an improved method is proposed to be used for cylindrical as well as spherical pore geometries based on the BJH algorithm. This term was obtained adjusting simulated isotherms with different values of f _c to the experimental isotherm. The results were compared to those obtained by traditional methods and by the Non-Local Density Functional Theory (NLDFT) model.     

Guaiacol HDO on La-modified Pt/Al2O3: Influence of rare-earth loading

The stability of the catalyst used in hydrodeoxygenation (HDO) of biomass-derived oils needs improvement. La has been applied in delaying Al₂O₃ phase-change under reaction conditions. Lanthanum (0.5–8 wt.%)-γ-alumina was studied as Pt (1 wt.%) carrier aimed at guaiacol (GUA) HDO. Materials characterization included N₂ physisorption, X-ray diffraction (XRD), thermal analysis, FTIR, UV–vis, and TPR. Solids pore size (~8–10 nm) was suitable for GUA (kinetic diameter~0.668 nm) hydrotreating. Mixed carriers were amorphous (XRD), suggesting well-dispersed La domains; meanwhile, carbonates/bicarbonates were formed (from CO₂) due to the basic surface properties of modified supports (FTIR). That could impart catalyst stability by inhibiting coking through the passivation of Lewis acidity on Al₂O₃. Pt reducibility increased with La loading in various formulations. However, that was not reflected in enhanced GUA HDO (T = 488 K and P = 3.2 MPa, batch reactor), presumably due to the strong metal–support interaction (SMSI), where LaO_x covered the metallic Pt particle surface. GUA HDO on various catalysts was approximated by pseudo-first-order kinetics (integral regime, k), where deviations were observed as La loading increased, presumably by an SMSI state that could affect the rate-determining step of the reaction mechanism. Basic sites provided by rare-earth could contribute to altering HDO reaction pathways as well. At 1 wt.% rare-earth, GUA HDO was maximized (k~25% higher than that on Pt/Al₂O₃), with that material also exhibiting similar deoxygenation (85%–90% at total GUA conversion) to the latter Pt over pristine alumina. Conversely, both parameters significantly diminished over the catalyst of the highest La content. Materials at low rare-earth concentrations deserve further studies focused on catalyst stability under HDO conditions.     

Nanofiber‐reinforced thermoplastic composites. I. Thermoanalytical and mechanical analyses

This article is a portion of a comprehensive study on carbon nanofiber–reinforced thermoplastic composites. The thermal behavior and dynamic and tensile mechanical properties of polypropylene–carbon nanofibers composites are discussed. Carbon nanofibers are those produced by the vapor‐grown carbon method and have an average diameter of 100 nm. These hollow‐core nanofibers are an ideal precursor system to working with multiwall and single‐wall nanotubes for composite development. Composites were prepared by conventional Banbury‐type plastic‐processing methods ideal for low‐cost composite development. Nanofiber agglomerates were eliminated because of shear working conditions, resulting in isotropic compression‐molded composites. Incorporation of carbon nanofibers raised the working temperature range of the thermoplastic by 100°C. The nanofiber additions led to an increase in the rate of polymer crystallization with no change in the nucleation mechanism, as analyzed by the Avrami method. Although the tensile strength of the composite was unaltered with increasing nanofiber composition, the dynamic modulus increased by 350%. The thermal behavior of the composites was not significantly altered by the functionalization of the nanofibers since chemical alteration is associated with the defect structure of the chemical vapor deposition (CVD) layer on the nanofibers. Composite strength was limited by the enhanced crystallization of the polymer brought on by nanofiber interaction as additional nucleation sites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 125–133, 2001