Bioinspired Intervertebral Disc with Multidirectional Stiffness Prepared via Multimaterial Additive Manufacturing

Degenerative disc disease (DDD) has become a significant public health issue worldwide. This can result in loss of spinal function affecting patient health and quality of life. Artificial total disc replacement (A-TDR) is an effective approach for treating symptomatic DDD that compensates for lost functionality and helps patients perform daily activities. However, because current A-TDR devices lack the unique structure and material characteristics of natural intervertebral discs (IVDs), they fail to replicate the multidirectional stiffness needed to match physiological motions and characterize anisotropic behavior. It is still unclear how the multidirectional stiffness of the disc is affected by structural parameters and material characteristics. Herein, a bioinspired intervertebral disc (BIVD-L) based on a representative human lumbar segment is developed. The proposed BIVD-L reproduces the multidirectional stiffness needed for the most common physiological kinematic behaviors. The results demonstrate that the multidirectional stiffness of the BIVD-L can be regulated by structural and material parameters. The results of this research deepen knowledge of the biomechanical behavior of the human lumbar disc and may provide new inspirations for the design and fabrication of A-TDR devices for both engineering and functional applications.     

Microglial Cell Activation Increases Saturated and Decreases Monounsaturated Fatty Acid Content,but Both Lipid Species are Proinflammatory

Neuroinflammation is a component of age-related neurodegenerative diseases and cognitive decline. Saturated (SFA) and monounsaturated (MUFA) fatty acids are bioactive molecules that may play different extrinsic and intrinsic roles in neuroinflammation, serving as exogenous ligands for cellular receptors, or endogenous components of cell structural, energetic and signaling pathways. We determined the fatty acyl profile of BV2 microglial cells before and after acute activation with lipopolysaccharide (LPS). We also investigated the effect of SFA and MUFA pretreatment on the production of an invasive, neurotoxic phenotype in BV2 cells. Acute activation of BV2 microglia resulted in an increase in the relative content of SFA (12:0, 16:0, 18:0, 20:0, 22:0, and 24:0 increased significantly), and a relative decrease in the content of MUFA (16:1n7, 18:1n7, 18:1n9, 20:1n9, 24:1n9 decreased significantly). In agreement, the major stearoyl-CoA desaturase (SCD) isoform in BV2 cells, SCD2, was significantly down-regulated by LPS. We next treated cells with SFA (16:0 or 18:0) or MUFA (16:1n7 or 18:1n9), and found that levels of secreted IL6 were increased, as was secreted MMP9-mediated proteolytic activity. To test the functional significance, we treated SH-SY5Y neuronal cells with conditioned medium from BV2 cells pretreated with fatty acids, and found a small but significant induction of cell death. Our findings suggest differential intrinsic roles for SFA and MUFA in activated microglial cells, but similar extrinsic roles for these fatty acid species in inducing activation. Expansion of SFA is important during microglial cell activation, but either supplemental SFA or MUFA may contribute to chronic low-grade neuroinflammation.     

Assessment of Portuguese thermal building legislation in an energetic and environmental perspective

The aim of this study is to assess the consistency of Portuguese thermal building legislation in terms of energy and environmental performance.To illustrate this, a case study has been carried out for different scenarios of a dwelling home located in an extreme climate zone (I3, V1 north) in Portugal with a T3 typology: four occupants and net floor area of 150 m², modelled according to Regulation Thermal Performance Characteristics of Buildings and a Life Cycle Assessment approach.The results show that the Portuguese thermal building legislation can be considered consistent in terms of energy efficiency and environmental performance if we take the damage categories into account - “human health” or “ecosystem quality” or the impact category - “emission into air”. It cannot be considered consistent if we take the damage category into account - “resources” or the impact category - “CO₂ eq” (equivalent carbon dioxide emissions)/“climate change”/“global warming”.     

Contribution of semi-quantum dielectric function models to the analysis of infrared spectra

A new approach to modeling using semi-quantum dielectric function models is proposed for the retrieval of the optical functions from infrared spectra. The powerful points of the method are shown throughout the analysis of two semitransparent materials, MgO and KBr. All the results are discussed in light of those obtained with classical techniques. This type of model is able to retrieve, for example, the extinction index in a range that covers at least six orders of magnitude and gives access to highly valuable information about high-order phonon processes.     

Learning to Match the Schemas of Data Sources: A Multistrategy Approach

The problem of integrating data from multiple data sources—either on the Internet or within enterprises—has received much attention in the database and AI communities. The focus has been on building data integration systems that provide a uniform query interface to the sources. A key bottleneck in building such systems has been the laborious manual construction of semantic mappings between the query interface and the source schemas. Examples of mappings are element location maps to address and price maps to listed-price. We propose a multistrategy learning approach to automatically find such mappings. The approach applies multiple learner modules, where each module exploits a different type of information either in the schemas of the sources or in their data, then combines the predictions of the modules using a meta-learner. Learner modules employ a variety of techniques, ranging from Naive Bayes and nearest-neighbor classification to entity recognition and information retrieval. We describe the LSD system, which employs this approach to find semantic mappings. To further improve matching accuracy, LSD exploits domain integrity constraints, user feedback, and nested structures in XML data. We test LSD experimentally on several real-world domains. The experiments validate the utility of multistrategy learning for data integration and show that LSD proposes semantic mappings with a high degree of accuracy.     

Increase of critical current density and voltage for triggering avalanche injection through use of graded collector doping

In this paper it is shown that both critical current density and voltage of an epitaxial bipolar power transistor with an inductive load, which are taken as a measure of its susceptibility to avalanche injection, can be significantly increased by using double graded collector doping profiles. The first graded portion gives the required current protection level and the steeper second graded profile can be used to increase the voltage protection level. Calculations are carried out for optimum collector parameters to achieve minimum resistance for the required open base breakdown voltage. Results are compared with uniformly doped profile for the same collector resistance and open base voltage. It is shown that a device with graded collector is less prone to failure due to avalanche injection.     

Characterization of a redox-modified clay mineral with respect to its suitability as a barrier in radioactive waste confinement

Engineered barriers for high-level nuclear waste (HLW) consist of excavated repositories in sub-surface rock formations where canisters holding the radionuclide are stored. Clay minerals, particularly the swelling 2:1 types, are used as backfill material, both in the canisters and in the bore hole, in order to prevent radionuclide transport to surrounding groundwater. One of the most important risks that can occur is the corrosion of the canister, which could be coupled with reduction of iron (Fe) in the clay structure. Such changes could greatly decrease the long-term stability of the clay and, consequently, of the barriers themselves. In order to test the potential effects of such redox interactions, an Fe-bearing clay mineral from a commercial source located in the Kutch region, India, was selected for study. This particular mineral is one of the candidate clay minerals to serve as such a barrier material, and is the one with the largest structural Fe content. Results from it should, therefore, provide maximum insight into the potential effects of redox interactions between the barrier and its surroundings. The unaltered clay was characterized by X-ray powder diffractometry (XRD), thermal gravimetric analysis (TGA/DTGA), Fourier-transform infrared (FTIR) spectroscopy, and variable-temperature Mössbauer spectroscopy. The chemically reduced and reoxidized forms of the clay were characterized by variable-temperature Mössbauer spectroscopy and chemical analysis. In the unaltered state the clay is comprised of smectite, maghemite, superparamagnetic goethite, and hematite, with a possible trace of kaolinite. In the reduced state the Fe (oxyhydr)oxides were dissolved. Upon reoxidation no six-line pattern was observed, indicating that the Fe remained only in the structure of the silicates. The final structure of the reduced–reoxidized clay contained more defects than the original clay, as revealed by greater quadrupole splitting values for structural Fe(III) in the clay. These findings indicate that upon exposure to natural redox cycles the Kutch clay could undergo permanent changes in its mineralogical composition and clay mineral structure, but further study is required to ascertain the effects that such changes would have on its long-term stability as a barrier material.     

Effects of initial climatic conditions on growth and accumulation of fluoride and nitrogen in leaves of two tropical tree species exposed to industrial air pollution

Saplings of Tibouchina pulchra and Psidium guajava, cultivated under standardized soil conditions, were placed in two sites at Cubat?o (state of S?o Paulo, southeast Brazil) to study the effects of air pollution on growth, biomass allocation and foliar nitrogen and fluoride concentrations. Thirty-six potted plants were maintained over two periods of one year (Jul/00 to Jun/01; Dec/00 to Nov/01) at each of two experimental sites with distinct levels of air pollution: Pil?es River Valley (PV) with vegetation virtually unaffected by air pollution; and Mogi River Valley (MV) severely affected by pollutants released mainly by chemical, fertilizer, iron and steel industries. For both species, saplings growing at MV showed alterations of growth and biomass allocation, as well as increased leaf concentrations of nitrogen and fluoride. Comparing both experimental periods, the one starting in winter (the driest season in Southeastern Brazil) seemed to affect the saplings more severely, the differences of the measured parameters between MV and PV being higher than in the second period. Multivariate analysis revealed two groups of data: one representing the MV and the other the PV saplings. For both species, saplings growing at MV showed differences in chemical composition, growth and biomass allocation, compared with the PV saplings. The results suggested that seasonal conditions of the first months of sapling exposure (summer or winter) modulate the intensity of responses to pollution stress.     

Chemical composition and physical properties of black liquors and their effects on liquor recovery operation in Brazilian pulp mills

Black liquor is the major by-product and fuel of pulp mills. In this work, effects of black liquor properties on its recovery unit operation are analyzed. Thus, an experimental methodology for characterizing the principal chemical and physical properties of eucalyptus Kraft and bamboo soda black liquors has been developed, including sample collections from six Brazilian mills. Based on results, eucalyptus and bamboo black liquors present higher contents of non-processing elements (NPEs), higher concentration and different molar mass of lignin than those reported by the pine Kraft black liquor. This leads to distinct rheological properties of these liquors. By comparing results obtained for the both liquors, the bamboo and the eucalyptus, the former has the lowest sulfur level, the highest silicon and lignin concentration and, consequently, the highest apparent viscosity.     

Tissue distribution and depuration kinetics of waterborne 14C-labeled light PAHs in mummichog (Fundulus heteroclitus)

Light polycyclic aromatic hydrocarbons (PAHs) of petrogenic origin are commonly found in estuaries and coastal areas. Though they are known to be toxic to fish, little is known about their uptake and tissue distribution. This paper reports on the results of a study on uptake, elimination, and tissue distribution of three waterborne 14C-labeled PAHs in the mummichog, Fundulus heteroclitus, using whole-body autoradiography. After a 24 h exposure to 1 μCi·L(-1) of 14C-naphthalene, 14C-1-naphthol, and 14C-phenanthrene, fish were transferred to clean water and tissue distribution examined after 0, 1, 3, 7, 14, and 21 days of depuration. All compounds were readily accumulated by fish and were also rapidly eliminated (t0.5 range=1.1 to 3.0 days). Most of the radioactivity in naphthalene- and phenanthrene-treated fish was found in gall bladder?liver>intestinal lumen. In naphthol-exposed fish, an important labeling of some brain areas was observed. Brain of naphthalene-exposed fish was also labeled after 24 h depuration, indicating that exposure to naphthalene may result in metabolite accumulation in the brain. This is the first study showing that naphthalene, naphthol, and/or unidentified metabolite(s) can accumulate in brain tissues, which may impair normal brain function.