RESUMO
Transparent ceramics like magnesium aluminate spinel (MAS) are considered the next step in material evolution showing unmatched mechanical, chemical and physical resistance combined with high optical transparency. Unfortunately, transparent ceramics are notoriously difficult to shape, especially on the microscale. Therefore, a thermoplastic MAS nanocomposite is developed that can be shaped by polymer injection molding at high speed and precision. The nanocomposite is converted to dense MAS by debinding, pre-sintering, and hot isostatic pressing yielding transparent ceramics with high optical transmission up to 84 % and high mechanical strength. A transparent macroscopic MAS components with wall thicknesses up to 4 mm as well as microstructured components with single micrometer resolution are shown. This work makes transparent MAS ceramics accessible to modern high-throughput polymer processing techniques for fast and cost-efficient manufacturing of macroscopic and microstructured components enabling a plethora of potential applications from optics and photonics, medicine to scratch and break-resistant transparent windows for consumer electronics.
Assuntos
Cerâmica , Nanocompostos , PolímerosRESUMO
The vertebrate fossil record of the Pampean Region of Argentina occupies an important place in South American vertebrate paleontology. An abundance of localities has long been the main basis for constructing the chronostratigraphical/geochronological scale for the late Neogene-Quaternary of South America, as well as for understanding major patterns of vertebrate evolution, including the Great American Biotic Interchange. However, few independently-derived dates are available for constraining this record. In this contribution, we present new 40Ar/39Ar dates on escorias (likely the product of meteoric impacts) from the Argentinean Atlantic coast and statistically-based biochronological analyses that help to calibrate Late Miocene-Pliocene Pampean faunal successions. For the type areas of the Montehermosan and Chapadmalalan Ages/Stages, our results delimit their age ranges to 4.7-3.7 Ma and ca. 3.74-3.04 Ma, respectively. Additionally, from Buenos Aires Province, dates of 5.17 Ma and 4.33 Ma were recovered for "Huayquerian" and Montehermosan faunas. This information helps to better calibrate important first appearances of allochthonous taxa in South America, including one of the oldest records for procyonids (7.24-5.95 Ma), cricetids (6.95-5.46 Ma), and tayassuids (> 3.74 Ma, oldest high-confidence record). These results also constrain to ca. 3 Ma the last appearances of the autochthonous sparassodonts, as well as terror birds of large/middle body size in South America. South American faunal turnover during the late Neogene, including Late Pliocene extinctions, is interpreted as a consequence of knock-on effects from global climatic changes and initiation of the icehouse climate regime.
Assuntos
Argônio/análise , Biodiversidade , Evolução Biológica , Radioisótopos/análise , Vertebrados/fisiologia , Animais , Argentina , FósseisRESUMO
The degradation efficiency of the Fenton reaction or ozonolysis (O3) to treat soil contaminated by crude petroleum was studied in association with the sonolysis process. To quantify oxidation efficiency, total organic carbon (TOC) and chemical oxygen demand (COD) were measured, while biochemical oxygen demand (BOD5) was measured to estimate biodegradation potential. TOC removal efficiency ranged from 9 to 52% to the Fenton reaction without sonolysis, and 18% and 78% with sonolysis for reagent concentrations of 1% H2O2-100 mM Fe2+ and 20% H2O2-1 mM Fe2+, respectively. For ozonolysis (after 10 and 60 min of treatment), the reduction in TOC ranged from 9 to 43% without sonolysis and 15 to 61% with sonolysis. The Fenton reaction without sonolysis increased the biodegradability in relation to the non-oxidized sample by 6% (1% H2O2-100 mM Fe2+) and 26% (20% H2O2-1 mM Fe2+), and with sonolysis the corresponding values were 13% and 42%, respectively. The biodegradation potential under ozonolysis without sonolysis increased from 0.18 (10 min of treatment) to 0.38 (30 min of treatment), and with sonolysis these values were 0.26 and 0.58, respectively. Optimization of the remediation processes is essential to determine sequential treatment order and efficiency.
Assuntos
Ozônio , Petróleo , Poluentes Químicos da Água , Peróxido de Hidrogênio , Ferro , Oxirredução , Solo , Poluentes Químicos da Água/análiseRESUMO
Stress is implicated in the etiology of major depressive disorder (MDD) and leads to the activation of proinflammatory pathways, which are recognized to induce depressive symptoms. For instance, depression is commonly observed in patients with hepatitis C and cancer under IFN therapy, and high levels of inflammatory cytokines are described in the serum of individuals with MDD - which indicate a multi-system aspect of psychiatric disorders. Thus, we evaluated the effects of a two-hit model of depression on peripheral and CNS inflammatory, neurotrophic, and oxidative stress parameters and behavior. Male Wistar rats were submitted to lipopolysaccharide (LPS) injections, followed by a chronic unpredictable mild stress (CUMS) protocol. Rats exposed to CUMS (CUMS + groups) exhibited reduced body weight, sucrose consumption and preference as well as an increased score of coat state and locomotor behavior. Interestingly, higher IFNγ serum levels were observed in the LPS/CUMS + group, which were further correlated with reduced sucrose consumption. Hypertrophy of adrenal gland was also observed in CUMS+, and splenic hypertrophy was exclusive of LPS-injected animals. Brain-derived neurotrophic factor (BDNF) levels were decreased in the serum of CUMS + animals, while no differences were found in the hippocampus and on lipid peroxidation levels. Besides corroborating the effectiveness of the CUMS model on inducing depressive-like behavior, our findings suggest that the combination of different etiological and pathophysiological components of MDD may provide with a more translational approach. Also, the correlation of increased IFNγ peripheral levels with an anhedonic-like phenotype reinforce the contemporary concept of psychiatric disorders being considered multi-system inflammatory diseases.
Assuntos
Anedonia/fisiologia , Interferon gama/sangue , Animais , Encéfalo/metabolismo , Depressão/sangue , Transtorno Depressivo Maior/sangue , Modelos Animais de Doenças , Hipocampo/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Estresse Oxidativo/fisiologia , Ratos , Ratos Wistar , Estresse Psicológico/sangueRESUMO
A 4-year-old boy had an autonomic seizure of Panayiotopoulos syndrome during video-EEG recording. Interictal EEG showed multifocal spikes in the centrotemporal and left posterior regions. Ictal electrographic onset included fast rhythms in the left posterior regions progressing to a mixture of high-amplitude spikes and fast and slow rhythms, bilaterally. The clinical symptoms (sighing, arousal with eyes opening, eye-deviation, and emesis with possible alteration of consciousness) started two minutes after the electrographic onset. These symptoms were mild and their characterisation as epileptic seizure behaviour would have been difficult without the ictal EEG documentation. The clinical manifestations of the child's previous epileptic seizures were mainly from the Rolandic area. [Published with video sequences].
Assuntos
Doenças do Sistema Nervoso Autônomo/fisiopatologia , Encéfalo/fisiopatologia , Epilepsias Parciais/fisiopatologia , Estado Epiléptico/fisiopatologia , Doenças do Sistema Nervoso Autônomo/complicações , Pré-Escolar , Eletroencefalografia , Epilepsias Parciais/complicações , Humanos , Masculino , SíndromeRESUMO
In memory of the 200th anniversary of the eminent Austrian pathologist Carl von Rokitansky (1804-1874) this paper deals with his outstanding thoughts on general pathology as well as his own papers on different aspects of organised matter and some other general problems of life. In the first line Rokitansky wanted to be a medical practitioner, but the insufficiency of the medical practice of his time led him to seek a way of reform by putting pathology on a new rationalistic basis. Thus he eliminated all speculative elements, which had dominated pathology up to his time. Opposite to Rudolf Virchow, Rokitansky used materialistic methods only as working tools in order to bring about new results in research, but never became himself a materialist in thinking. Being influenced by Kant and Schopenhauer, Rokitansky's private philosophy tended more to idealism.