565 research outputs found
Atomic-level understanding of a formamidinium hybrid halide perovskite, FAPbBr<sub>3</sub>
Herein, we show how electron microscopy can provide atomic-level understanding of FAPbBr3 , where electron diffraction and high-resolution imaging were combined allowing not only the characterization of the pristine material but also the identification of different intermediates upon its structural disintegration. Additionally, a minor tetragonal phase was also identified whose structure was also solved
Synthesis of zeolite A using raw kaolin from Ethiopia and its application in removal of Cr(III) from tannery wastewater
BACKGROUND: The commercial production of zeolite A mainly involves costly synthetic chemicals. However, cheaper raw materials such as clay minerals, coal ashes, natural zeolites, solid wastes and industrial sludge have been tested. Based on this, the objective of the present study is synthesis of zeolite A from two sources of raw kaolins (Ansho and Bombowha) from Ethiopia and evaluation of its application in tannery wastewater treatment. RESULTS: The synthesis result indicated high crystallinity (>90%) of zeolite A using Ansho kaolin. Lower grade Bombowha kaolin yielded zeolite A with crystallinity of 80%. In the tannery wastewater treatment study, a real sample having chromium concentration of 2036 mg L-1 was treated, obtaining 99.8% removal and about 200 mg g-1 adsorption capacity of Cr(III) using 100 g L-1 and 5 g L-1 adsorbent dose, respectively. This indicated that the synthesized zeolite A has great potential for Cr(III) removal from tannery wastewater. CONCLUSION: In this study, zeolite A has been synthesized from two sources of kaolin from Ethiopia and has been evaluated in tannery wastewater treatment. The synthesis result indicated the formation of crystals of zeolite A with optimum crystallinity of 91% and the material exhibited chromium removal efficiency of 99.8%
Biomechanics of <i>Machaeracanthus</i> pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans
Acanthodians are a major group of Paleaozoic jawed vertebrates that constitute a paraphyletic assemblage of stem-chondrichthyans (Brazeau and Friedman, 2015). Representatives of this group are characterized, among other traits, by the presence of bony spines in front of all paired and median fins except the caudal (Denison, 1979), which has given rise to their colloquial name of 'spiny sharks'. The occurrence of pectoral fin spines is recognized as a potential gnathostome synapomorphy (Miller et al., 2003) or symplesiomorphy (Coates, 2003), being also present in other major groups of Paleaozoic jawed vertebrates, including placoderms (Young, 2010), 'non-acanthodian' chondrichthyans (Miller et al., 2003), and osteichthyans (Zhu et al., 1999). However, this trait was independently lost in the later evolutionary history of these lineages and is absent in most living representatives (Coates, 2003; Miller et al., 2003), with the exception of catfishes (Siluriformes), that acquired pectoral fin spines as an evolutionary reversion (Price et al., 2015). As a consequence, the paucity of living analogsue precludes deriving functional interpretations of those structures and the role that they fulfilled in life remains unclear, despite this having the potential to enrich our understanding on the ecologies and lifestyles of groups of early jawed vertebrates. Machaeracanthus constitutes a genus of acanthodians that ranged from the Late Silurian to the Middle Devonian, which is known from fin spines, scales, and a few endoskeletal remains (Burrow et al., 2010; Botella et al., 2012). The spines of this genus differ from the fin spines of all other acanthodians and sharks in presenting a marked cross-sectional asymmetry and a totally enclosed central canal, which is usually open along the proximal end of the trailing edge in other taxa (Burrow et al., 2010). The description of wear patterns at the tips of pectoral fin spines of Machaeracanthus and their peculiar arrangement in pairs has led some authors to propose that these elements could have been used as 'snow-shoes' to lay on and prevent sinking into the substrate below or even to propel itself along the bottom (Südkamp and Burrow, 2007). Here, we test this hypothesis through beam theory analyses and provide evidence that the biomechanical properties of Machaeracanthus pectoral fin spines are compatible with this interpretation, thus shedding light on the diversity of the functions of these intriguing anatomical structures and the lifestyles of some of the earliest jawed vertebrates
Visual Targeted Advertisement System Based on User Profiling and Content Consumption for Mobile Broadcasting Television
Content personalisation is one of the main aims of the mobile media delivery business models, as a new way to improve the user’s experience. In broadcasting networks, the content is sent “one to many”, so a complete personalisation where the user may select any content is not possible. But using the mobile bidirectional return channel (e.g. UMTS connection) visual targeted advertising can be performed in a simple way: by off-line storing the advertisement for selectively replacing the normal broadcasted advertisement. In fact, these concepts provide powerful methods to increase the value of the service, mainly in mobile environments. In this article we present a novel intelligent content personalisation system for targeted advertising over mobile broadcasting networks and terminals, based on user profiling and clustering, as a new solution where the use of content personalisation represents the competitive advantage over traditional advertising
Farnesyl Phosphatase, a Corpora allata Enzyme Involved in Juvenile Hormone Biosynthesis in Aedes aegypti
Background: The juvenile hormones (JHs) are sesquiterpenoid compounds that play a central role in insect reproduction, development and behavior. The late steps of JH III biosynthesis in the mosquito Aedes aegypti involve the hydrolysis of farnesyl pyrophosphate (FPP) to farnesol (FOL), which is then successively oxidized to farnesal and farnesoic acid, methylated to form methyl farnesoate and finally transformed to JH III by a P450 epoxidase. The only recognized FPP phosphatase (FPPase) expressed in the corpora allata (CA) of an insect was recently described in Drosophila melanogaster (DmFPPase). In the present study we sought to molecularly and biochemically characterize the FPP phosphatase responsible for the transformation of FPP into FOL in the CA of A. aegypti.
Methods: A search for orthologs of the DmFPPase in Aedes aegypti led to the identification of 3 putative FPPase paralogs expressed in the CA of the mosquito (AaFPPases-1, -2, and -3). The activities of recombinant AaFPPases were tested against general phosphatase substrates and isoprenoid pyrophosphates. Using a newly developed assay utilizing fluorescent tags, we analyzed AaFPPase activities in CA of sugar and blood-fed females. Double-stranded RNA (dsRNA) was used to evaluate the effect of reduction of AaFPPase mRNAs on JH biosynthesis.
Conclusions: AaFPPase-1 and AaFPPase-2 are members of the NagD family of the Class IIA C2 cap-containing haloalkanoic acid dehalogenase (HAD) super family and efficiently hydrolyzed FPP into FOL. AaFPPase activities were different in CA of sugar and blood-fed females. Injection of dsRNAs resulted in a significant reduction of AaFPPase-1 and AaFPPase-2 mRNAs, but only reduction of AaFPPase-1 caused a significant decrease of JH biosynthesis. These results suggest that AaFPPase-1 is predominantly involved in the catalysis of FPP into FOL in the CA of A. aegypti
IgE-Mediated Hypersensitivity Reactions to Cannabis in Laboratory Personnel
Background: There have been sporadic reports of hypersensitivity reactions to plants of the Cannabinaceae family (hemp and hops), but it has remained unclear whether these reactions are immunologic or nonimmunologic in nature. Objective: We examined the IgE-binding and histamine-releasing properties of hashish and marijuana extracts by CAP-FEIA and a basophil histamine release test. Methods: Two workers at a forensic laboratory suffered from nasal congestion, rbinitis, sneezing and asthmatic symptoms upon occupational contact with hashish or marijuana, which they had handled frequently for 25 and 16 years, respectively. Neither patient had a history of atopic disease. Serum was analyzed for specific IgE antibodies to hashish or marijuana extract by research prototype ImmunoCAP, and histamine release from basophils upon exposure to hashish or marijuana extracts was assessed. Results were matched to those of 4 nonatopic and 10 atopic control subjects with no known history of recreational or occupational exposure to marijuana or hashish. Results: Patient 1 had specific IgE to both hashish and marijuana (CAP class 2), and patient 2 to marijuana only (CAP class 2). Controls proved negative for specific IgE except for 2 atopic individuals with CAP class 1 to marijuana and 1 other atopic individual with CAP class 1 to hashish. Stimulation of basophils with hashish or marijuana extracts elicited histamine release from basophils of both patients and 4 atopic control subjects. Conclusions: Our results suggest an IgE-related pathomechanism for hypersensitivity reactions to marijuana or hashish. Copyright (C) 2011 S. Karger AG, Base
Diagnosis of Transient/Latent HPV Infections - A Point of View!
© 2018 IMSS Diagnosis of transient/latent HPV infections requires a rethinking of ideas concerning the host virus relationship. With this in mind, we address several concepts, such as mutualism and commensalism, to understand better the different stages of development, in addition to briefly covering current methods of detection. We suggest analyzing molecules related to the innate immune response for earlier diagnosis
Experiencias de una red docente: aprendizaje significativo en ciencias y tecnología mediante gamificación
En el aprendizaje de los contenidos de materias científico-técnicas es especialmente importante la motivación del estudiante mediante referencias y ejercicios de casos reales donde se trata de reducir la memorización de muchos conceptos reforzando el aprendizaje significativo. De este modo, el método de aprendizaje significativo basado en gamificación se lleva a cabo mediante el uso de técnicas, elementos y dinámicas propias de los juegos y el ocio en actividades docentes con el fin de potenciar la motivación, así como de reforzar la conducta para solucionar problemas, mejorar la productividad, obtener objetivos, activar el aprendizaje y evaluar a los alumnos. En esta comunicación se explicará el proceso de puesta en común, diseño, desarrollo y evaluación de las experiencias de una Red Docente que ha empleado la gamificación como metodología para conseguir el aprendizaje significativo de los alumnos. La acción se ha llevado a cabo en las asignaturas de segundo cuatrimestre en los Estudios de Grado de Química, Biología, Ciencias Ambientales, Ingeniería de la salud, Bioquímica e Ingeniería de Telecomunicación de la Universidad de Málaga que imparten los profesores que componen la Red Docente. Para llevarla a cabo los profesores han conseguido una ayuda para fomentar la creación e implantación de redes docentes de excelencia gracias al Plan Propio Integral de Docencia de la Universidad de Málaga.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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