6,561 research outputs found
Letter to the editor concerning “Liver transplantation for metastatic wild-type gastrointestinal stromal tumor in the era of molecular targeted therapies: Report of a first case"
N
Sustainable Recycling of Insoluble Rust Waste for the Synthesis of Iron-Containing Perovskite-Type Catalysts
Insoluble rust waste from the scraping of rusted iron-containing materials represents a cheap, eco-friendly, and available source of iron. LaFeO3 perovskite-type powders were successfully prepared by solution combustion synthesis using rust waste from an electricity transmission tower manufacturer. Solution combustion synthesis enabled introduction of this insoluble iron precursor directly into the final product, bypassing complex extraction procedures. Catalytic activity in the propylene oxidation of the waste-derived LaFeO3 with stoichiometric Fe/La ratio was almost identical to the commercial iron nitrate-derived LaFeO3 , thus demonstrating the viability of this recycling solution. The amount of waste iron precursor was varied and its effect on the powder properties was investigated. A lesser stoichiometric amount of precursor produced a LaFeO3 -La2O3 binary system, whereas a higher stoichiometric amount led to a LaFeO3 -Fe2O3 binary system. Catalytic activity of iron-rich compositions in the propylene oxidation was only slightly lower than the stoichiometric one, whereas iron-poor compositions were much less active. This eco-friendly methodology can be easily extended to other iron perovskites with different chemical compositions and to other iron-containing compounds
The ring-shaped thermal field of Stefanos crater, Nisyros Island: a conceptual model
Fumarole fields related to
hydrothermal processes release the heat of the underground through permeable
pathways. Thermal changes, therefore, are likely to depend also on the size
and permeability variation of these pathways. There may be different
explanations for the observed permeability changes, such as fault control,
lithology, weathering/alteration, heterogeneous sediment accumulation/erosion
and physical changes of the fluids (e.g., temperature and viscosity). A
common difficulty, however, in surface temperature field studies at active
volcanoes is that the parameters controlling the ascending routes of fluids
are poorly constrained in general. Here we analyze the crater of Stefanos,
Nisyros (Greece), and highlight complexities in the spatial pattern of the
fumarole field related to permeability conditions. We combine high-resolution
infrared mosaics and grain-size analysis of soils, aiming to elaborate
parameters controlling the appearance of the fumarole field. We find a
ring-shaped thermal field located within the explosion crater, which we
interpret to reflect near-surface contrasts of the soil granulometry and
volcanotectonic history at depth. We develop a conceptual model of how the
ring-shaped thermal field formed at the Stefanos crater and similarly at
other volcanic edifices, highlighting the importance of local permeability
contrast that may increase or decrease the thermal fluid flux
Numerical simulation and experimental validation of fatigue behavior of wood-glass fiber composite T joint
In this paper, a numerical FE model is developed with ANSYS and validated by experimental tests to identify possible
damage locations and fatigue breakage in different wood-glass fiber composite T-joints for marine applications. Both
static and fatigue tests in three-point bending configuration have been performe
SDHA Germline Mutations in SDH-Deficient GISTs: A Current Update
Loss of function of the succinate dehydrogenase complex characterizes 20-40% of all KIT/PDGFRA-negative GIST. Approximately half of SDH-deficient GIST patients lack SDHx mutations and are caused by a hypermethylation of the SDHC promoter, which causes the repression of SDHC transcription and depletion of SDHC protein levels through a mechanism described as epimutation. The remaining 50% of SDH-deficient GISTs have mutations in one of the SDH subunits and SDHA mutations are the most common (30%), with consequent loss of SDHA and SDHB protein expression immunohistochemically. SDHB, SDHC, and SDHD mutations in GIST occur in only 20-30% of cases and most of these SDH mutations are germline. More recently, germline mutations in SDHA have also been described in several patients with loss of function of the SDH complex. SDHA-mutant patients usually carry two mutational events at the SDHA locus, either the loss of the wild type allele or a second somatic event in compound heterozygosis. This review provides an overview of all data in the literature regarding SDHA-mutated GIST, especially focusing on the prevalence of germline mutations in SDH-deficient GIST populations who harbor SDHA somatic mutations, and offers a view towards understanding the importance of genetic counselling for SDHA-variant carriers and relatives
Positive and Negative Regulation of Cellular Immune Responses in Physiologic Conditions and Diseases
The immune system has evolved to allow robust responses against pathogens while avoiding autoimmunity. This is notably enabled by stimulatory and inhibitory signals which contribute to the regulation of immune responses. In the presence of a pathogen, a specific and effective immune response must be induced and this leads to antigen-specific T-cell proliferation, cytokines production, and induction of T-cell differentiation toward an effector phenotype. After clearance or control of the pathogen, the effector immune response must be terminated in order to avoid tissue damage and chronic inflammation and this process involves coinhibitory molecules. When the immune system fails to eliminate or control the pathogen, continuous stimulation of T cells prevents the full contraction and leads to the functional exhaustion of effector T cells. Several evidences both in vitro and in vivo suggest that this anergic state can be reverted by blocking the interactions between coinhibitory molecules and their ligands. The potential to revert exhausted or inactivated T-cell responses following selective blocking of their function made these markers interesting targets for therapeutic interventions in patients with persistent viral infections or cancer
Thermodynamic and economic assessments of a hybrid PVT-ORC combined heating and power system for swimming pools
T he thermodynamic and economic performance of a solar combined heat and power (S - CHP) system based on an array of hybrid photovoltaic - thermal (PVT) collectors and an organic Rankine cycle (ORC) engine is considered for the provision of heating and power to swimming pool facilities . Priority is given to meet ing the thermal demand of the swimming pool , in order to ensure a comfortable condition for swimmers in cold er weather conditions, while excess thermal output from the collector s at high er temperatures is converted to electricity by the ORC engine in warm er weather conditions. The thermodynamic performance of this system and its dynamic characteristics are analysed on the basis of a transient thermodynamic model. Various heat losses and gains are considered in accordance to environmental and user - rela ted factors for both indoor and outdoor swimming pools. A case study is then performed for the swimming pool at the University Sport Centre (USC) of Bari, Italy. The r esults show that employing a zeotropic mixture of R245fa/ R227ea (30/70%) as the ORC working fluid allows such an ORC system to generate ~50% more power than when using pure R236ea due to the better temperature match of the cycle to the low - temperature hot - water heat source from the output of the PVT collectors . Apart from generating electricity, the ORC engine also alleviates PVT collector overheating , and reduc es the required size of the hot - water storage tank. With an installation of 2000 m 2 of PVT collectors, e nergetic analyses indicate that the proposed S - CHP system can cover 84 - 9 6 % of the thermal demand of the swimming pool during the warm summer months and 61 % of its annual ly integrated total thermal demand. In addition, the system produces a combined (from the collectors and ORC engine) of 328 MWh of electricity per year, corresponding to 36% of the total electricity demand of the USC , with ~4% coming from the ORC engine . The analysis suggests a minimum payback time of 12. 7 years with a n optimized tank volume of 125 m
Ruptured aortic arch aneurysm: transposition of aortic arch branches after insertion of thoracic endovascular stent with extra-anatomic brain perfusion
n/
- …