364 research outputs found
Two primary methods of proving gas flow meters
Methods for determining mass flow rates of gases for use in calibrating gas flowmeter
Sta Cast : Linee guida per la progettazione di getti in lega di alluminio
StaCast (New Quality and Design Standards for Aluminium Alloys Cast Products) è un progetto europeo dedicato allefonderie dell’alluminio con l’obiettivo di sviluppare una nuova classificazione dei difetti strutturali nei getti e di definiredei limiti di accettabilità di questi difetti a seconda della destinazione finale prevista. Il raggiungimento di questo obiettivoaiuterà significativamente le fonderie a ridurre il costo della non-qualità , migliorando nel contempo il loro margine dicompetitività grazie al conseguimento di importanti vantaggi, per esempio nei costi dell’energia. StaCast ha condotto unavasta indagine tra le fonderie europee per conoscere le caratteristiche principali della loro produzione, in quale misuraesse utilizzano gli Standard CEN, il bisogno di nuovi strumenti normativi riferiti ai difetti, alle proprietà meccaniche e allaprogettazione meccanica di getti in lega d’alluminio. Questo articolo presenta i principali risultati di tale indagine, che hacoinvolto circa 80 aziende, e l’impostazione dei documenti normativi che sono stati elaborati sulla Classificazione deiDifetti e sul Potenziale Meccanico di getti in lega d’alluminio
A review on the fluidity of al based alloys
Fluidity of molten metals is of significant importance in producing sound castings, particularly thin-walled castings.To meet the industrial demands of complex shaped castings, the knowledge of the parameters affecting fluidity is required in order to have a better control of the production processes.Since fluidity is one of the measures by which the castability of metals can be quantified, a definition and a description of castability are presented in this study.A definition of fluidity follows. Fluidity depends on many factors and this study reports the influence of the main factors: alloy composition, heat of fusion, superheat, grain refinement, modifying agents, mould material and temperature, melt cleanliness, coating and viscosity
Simulation of fluidity in AL-SI alloys
In this study, MAGMA soft® commercial software package was used to simulate the fluidity of A356 alloy. Established an optimum mesh generation, the influence of important metallurgical parameters, such as heat transfer coefficient, casting temperature and coherency temperature, on fluidity were simulated. The simulation results were compared with fluidity laboratory tests carried out with spiral-shaped sand moulds and the results from the simulations were found to be consistent with the experiments. Therefore, this study sets a basis for more extensive use of simulations as a means for predicting and optimizing the fluidity of aluminium alloys. In addition, the results from the spiral-shaped mould tests were compared with vacuum fluidity tests carried out using an A356 alloy and the two techniques showed consistent results
State-of-the-art characterization tools for Al foundry alloys
In this manuscript we review some characterization toolsfor Al foundry alloys. Castability is the ability of an alloyto be cast without formation of defects such as cracks,pores or misruns. Being able to measure, hence to control,these defects is fundamental and plays a critical role forthe development of numerical models for castability.Also melt quality influences these defects formation.Alloy dependent phenomena that determine castabilityare, among others, fluidity and porosity. This manuscriptfocuses on the main characterization tools for measuringfluidity, porosity and melt quality
On the quality of A354 ingots and its impact on cast product
A study in an automotive casting plant was targeted to address the problem of high rejection rate of a cylinder head casting made from an A354 alloy. Ingots of an A354 alloy from three different suppliers, A, B and C, were analyzed by the reduced pressure test (RPT) and the pressure filtration (PREFIL) test, individually as well as in combination. Hydrogen measurements during casting trials was carried out with an ALSPEK H? analyzer. The results have shown a good agreement with the scrap rate data of the final cast product, and the problem of higher scrap rate was significantly reduced when the ingots of an A354 alloy with the highest oxide content from supplier C were replaced. In order to study the influence of transfer and de-gassing on the melt quality, reduced pressure tests were also conducted along the production line. The effect of melt holding time on the quality of the cast product is also presented. The results from these trials shows that the bifilm index data from the RPT has a potential to be used in an industrial environment for routine melt quality control as the cause of high scrap was successfully identified with this technique
The complete genome sequence of human adenovirus 84, a highly recombinant new Human mastadenovirus D type with a unique fiber gene
Microparticle-mediated transfer of the viral receptors CAR and CD46, and the CFTR channel in a CHO cell model confers new functions to target cells
Cell microparticles (MPs) released in the extracellular milieu can embark plasma membrane and intracellular components which are specific of their cellular origin, and transfer them to target cells. The MP-mediated, cell-to-cell transfer of three human membrane glycoproteins of different degrees of complexity was investigated in the present study, using a CHO cell model system. We first tested the delivery of CAR and CD46, two monospanins which act as adenovirus receptors, to target CHO cells. CHO cells lack CAR and CD46, high affinity receptors for human adenovirus serotype 5 (HAdV5), and serotype 35 (HAdV35), respectively. We found that MPs derived from CHO cells (MP-donor cells) constitutively expressing CAR (MP-CAR) or CD46 (MP-CD46) were able to transfer CAR and CD46 to target CHO cells, and conferred selective permissiveness to HAdV5 and HAdV35. In addition, target CHO cells incubated with MP-CD46 acquired the CD46-associated function in complement regulation. We also explored the MP-mediated delivery of a dodecaspanin membrane glycoprotein, the CFTR to target CHO cells. CFTR functions as a chloride channel in human cells and is implicated in the genetic disease cystic fibrosis. Target CHO cells incubated with MPs produced by CHO cells constitutively expressing GFP-tagged CFTR (MP-GFP-CFTR) were found to gain a new cellular function, the chloride channel activity associated to CFTR. Time-course analysis of the appearance of GFP-CFTR in target cells suggested that MPs could achieve the delivery of CFTR to target cells via two mechanisms: the transfer of mature, membrane-inserted CFTR glycoprotein, and the transfer of CFTR-encoding mRNA. These results confirmed that cell-derived MPs represent a new class of promising therapeutic vehicles for the delivery of bioactive macromolecules, proteins or mRNAs, the latter exerting the desired therapeutic effect in target cells via de novo synthesis of their encoded proteins
Human AdV-20-42-42, a promising novel adenoviral vector for gene therapy and vaccine product development
Preexisting immune responses toward adenoviral vectors limit the use of a vector based on particular serotypes and its clinical applicability for gene therapy and/or vaccination. Therefore, there is a significant interest in vectorizing novel adenoviral types that have low seroprevalence in the human population. Here, we describe the discovery and vectorization of a chimeric human adenovirus, which we call HAdV-20-42-42. Full-genome sequencing revealed that this virus is closely related to human serotype 42, except for the penton base, which is derived from serotype 20. The HAdV-20-42-42 vector could be propagated stably to high titers on existing E1-complementing packaging cell lines. Receptor-binding studies revealed that the vector utilized both CAR and CD46 as receptors for cell entry. Furthermore, the HAdV-20-42-42 vector was potent in transducing human and murine cardiovascular cells and tissues, irrespective of the presence of blood coagulation factor X. In vivo characterizations demonstrate that when delivered intravenously (i.v.) in mice, HAdV-20-42-42 mainly targeted the lungs, liver, and spleen and triggered robust inflammatory immune responses. Finally, we demonstrate that potent T-cell responses against vector-delivered antigens could be induced upon intramuscular vaccination in mice. In summary, from the data obtained we conclude that HAdV-20-42-42 provides a valuable addition to the portfolio of adenoviral vectors available to develop efficacious products in the fields of gene therapy and vaccination
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