Minimizing Shrinkage Porosity by Optimizing Some Parameters of Al Alloy (6061T6) Using DOE

Response surface methodology is an efficient and powerful tool which is widely applied for casting optimization. In this research aluminum alloy wheel hub casting is done by using BOXBEHNKEN design, three level of each parameter were taken. Solid modeling of casting and gating system is done by CAD. Simulation of Aluminium Alloy (6061 T6) casting were perform in PRO-cast (2009.1) the simulation result indicates that selected parameters significantly affect the quality of casting. ANOVA is employed to examine the relationship between the factors. Input parameter namely flow rate, pouring temperature and runner size were taken to reduce the volume of shrinkage porosity. Experimental Design consist 15 experimental trials and output data obtained from simulation will be optimized through minitab-18. Result indicates that selected independent variables are significantly influence the response. ANOVA gives the optimized value of selected factors which reduces the porosity volume up to 30cm³. Keywords: Sand casting, Shrinkage porosity, Simulation, DOE, Response surface method.

Lead Recovery from a Lead Concentrate throughout Direct Smelting Reduction Process with Mixtures of Na2CO3 and SiC to 1000 °C

Lead was recovered through a direct smelting reduction route from a lead concentrate by using mixtures of Na2CO3 and SiC to 1000 °C. The lead concentrate was obtained from the mining State of Zacatecas, México by traditional mineral processing and froth flotation. The experimental trials showed that 86 wt.% of lead with a purity up to 97% can be recovered from the lead concentrate by a single step reduction process when 40 wt.% Na2CO3 and 0.4 g SiC were used in the initial charge. The process was modeled in the thermodynamic software FactSage 7.3 to evaluate the effect of adding different amounts of Na2CO3 on the lead recovery rates while holding constant the SiC amount and temperature. The stability phase diagram obtained showed that an addition of 34 wt.% Na2CO3 was enough to reach the highest lead recovery. It was observed that the interaction of Na2CO3 and SiC at a high temperature promotes the formation of C and Na2O, and SiO2, respectively, where the Na2O partially bonds with silica and sulfur forming Na2S and sodium silicates which may decrease the SO2 emissions and increase the weather degradation of the slag. The PbS was mainly reduced by the produced C and CO formed by the interaction between Na2CO3 and SiC at 1000 °C. The predicted results reasonably match with those obtained experimentally in the lead recovery rates and compounds formation.

Open Access Serials: the High Dilution Research case.

Open Access Serial seems to be the new paradigm in scientific publication representing a growing tendency in all society segments. In particular, we are interested in the application of the Open Access serial model to High Dilution research. Such multidisciplinary area is opened to experts from all area of knowledge, requiring experimental trials and models as well theoretical approaches. However these researchers must be brought together around a thematic serial, peer-reviewed and easily accessed, able to reach a high impact parameter without lose its focus, where theoretical backgrounds and concepts could be presented and intensely discussed, ranging from experimental to theoretical approaches, basic to applied researches, also reporting clinical, historical and sociological papers. The features of the Open Access fit well with the High Dilution community needs for a scientific serial. Also, an electronic support makes possible divulgate larger texts, figures, movies, interviews, audio, and any other kind of multimedia. Thus, an Open Access scientific serial dedicated to High Dilutions would be very well accepted by the international community involved in high dilutions research. Keywords: Open access, high dilution, online serial.  Publicações de acesso aberto: o caso da pesquisa em altas diluições Resumo A publicação de acesso aberto parece ser o novo paradigma em publicação científica, representando uma tendéncia crescente em todos os segmentos da sociedade. Nos interessa, em particular, a aplicação desse modelo na pesquisa das altas diluições. Essa área multisciplinar está aberta a especialistas de todas as áreas do saber, precisando de testes e modelos experimentais, assim como de abordagens teóricas. No entanto, esses pesquisadores devem ser reunidos ao redor de um periódico temático, revisado por pares e de fácil acesso, capaz de alcançar parâmetros de alto impacto sem perder seu foco, onde os marcos de referéncia e conceitos teóricos possam ser apresentados e intensamente discutidos, abarcando do experimental ao teórico, pesquisa básica e aplicada, pesquisas clínicas, históricas e sociológicas. As características do sistema aberto se correspondem adequadamente com os requerimentos de um periódico para a comunidade ligada às altas diluições. Igualmente, o meio eletrônico permite divulgar textos e gráficos de maior tamanho, filmes, entrevistas, áudio e outros tipos de formatos multimedia. Por esse motivo, um periódico científico de acesso aberto dedicado às altas diluições seria muito bem recebido pela comunidade internacional. Palavras-chave: Acesso aberto, altas diluições, periódicos online.  Publicaciones de acceso abierto: el caso de la investigación en altas diluciones Resumen La publicación de acceso abierto parece ser el nuevo paradigma en publicación científica, representando una tendencia creciente en todos los segmentos de la sociedad. En particular, nos interesa la aplicación de este modelo en la investigación de altas diluciones. Tal área multidisciplinar está abierta a especialistas de todas las áreas del saber, necesitando aún ensayos y modelos experimentales, así como abordajes teóricos. Sin embargo, estos investigadores deben ser reunidos en torno de un periódico temático, revisado por pares y de fácil acceso, capaz de alcanzar parámetros de alto impacto sin perder su foco, adonde los marcos de referencia y conceptos teóricos puedan ser presentados e intensamente discutidos, abarcando desde lo experimental a lo teórico, investigación fundamental y aplicada, investigaciones clínicas, históricas y sociológicas. Las características del sistema abierto tienen buena correspondencia con los requerimientos de un periódico para la comunidad vinculada a las altas diluciones. Igualmente, el medio electrónico permite divulgar textos y gráficos de mayor tamanho, películos, entrevistas, y otros tipos de formatos multimedia. Por ese motivo, un periódico científico de acceso abierto dedicado a las altas diluciones sería muy bien recebido por la comunidad internacional. Palabras-clave: Acceso abierto, altas diluciones, revistas online.  Correspondence author: Carlos Renato Zacharias, [email protected] How to cite this article: Zacharias CR. Open Access Serials: the High Dilution Research case. Int J High Dilution Res [online]. 2008 [cited YYYY Mmm DD]; 7(24): 159-162. Available from: http://journal.giri-society.org/index.php/ijhdr/article/view/267/359. ÂÂÂ

Application of Hydrogen Peroxide to Improve the Microbiological Stability of Food Ice Produced in Industrial Facilities

This work was aimed to produce an “active” food ice to preserve its microbiological safety over time. With this in mind, ice cubes were processed with the addition of H2O2 to water before freezing. Four food ice productions were performed at the industrial level: one control trial without the addition of H2O2 (0OX) and three experimental trials obtained by adding 4, 8, and 12 mg/L of H2O2 (4OX, 8OX, and 12OX), respectively. After production, all food ice trials were artificially contaminated with 102 CFU/100 mL of water-borne pathogenic bacteria (Escherichia coli ATCC 25922, Enteroccus faecalis ATCC 29212, and Pseudomonas aeruginosa ATCC 27853) inoculated individually. Thawed ice samples were then subjected to microbiological analyses performed by the membrane filtration method and the results indicated that only trial 12OX was able to inactivate all bacteria strains. In conclusion, the addition of 12 mg/L H2O2 represents an optimal cost-effective strategy to preserve the microbiological stability of food ice even when it is improperly handled after production.

Relative contact width evaluation of end hemispherical cavities rollers as an indication of Hertzian contact pressure

In a recent investigation, the end hemispherical cavities (EHC) rollers exhibited better strength against fracture than hollow rollers. Furthermore, EHC rollers looked promising from a higher fatigue life aspect than conventional solid rollers in a simulation study. Therefore, it necessitated further exploration of the EHC roller concept and to this end, in the present investigation, the contact widths of EHC rollers were relatively evaluated to judge its contact stresses' behavior with respect to the solid roller because the contact stresses are responsible for the fatigue life of rolling bearings. In the experiments, the contact footprints were obtained by forcing specimens of rollers against chemically etched surfaces and were examined by a microscope for measurement of contact widths. The experimental trials were performed with individual roller-on-plate tests and also with full-bearing samples. The etch correction factor was used to correct anomalies of real and observed contact widths due to etching film thickness. The parabolic relationships were established for roller variants which yielded constants signifying their relative ranks. The contact semi-widths, thus derived from corrected experimental results of individual roller-on-plate tests, demonstrated good agreement (<5%) with those derived from simulation results. The results of full-bearing sample tests for roller variants also ranked same as individual roller-on-plate tests. The encouraging results of contact semi-width assuredly favor the prospects of relatively higher fatigue life in case of EHC rollers.

Survival Benefit of Resection Surgery for Pancreatic Ductal Adenocarcinoma with Liver Metastases: A Propensity Score-Matched SEER Database Analysis

Guidelines do not recommend resection surgery for oligometastatic pancreatic ductal adenocarcinoma (PDAC). However, reports in small samples of selected patients suggest that surgery extends survival. Thus, this study aims to gather evidence for the benefits of cancer-directed surgery (CDS) by analyzing a national cohort and identifying prognostic factors that aid the selection of candidates for CDS or recruitment into experimental trials. Data for patients with PDAC and hepatic metastasis were extracted from the population-based Surveillance, Epidemiology, and End Results database (SEER). The bias between CDS and non-CDS groups was minimized with Propensity Score Matching (PSM), and the prognostic role of CDS was investigated by comparing Kaplan-Meier estimators and Cox proportional hazard models. A total of 12,018 patients were extracted from the database, including 259 patients who underwent CDS that were 1:1 propensity score-matched with patients who did not receive CDS. CDS appeared to significantly prolong median overall survival from 5 to 10 months. Multivariate analysis revealed chemotherapy as a protective prognostic, whilst survival was impaired by old age and tumors that were poorly differentiated (Grades III–IV). These factors can be used to select patients likely to benefit from CDS treatment, which may facilitate recruitment into randomized controlled trials.

Comparative vulnerability of Indosylvirana temporalis and Clinotarsus curtipes (Anura: Ranidae) tadpoles to water scorpions: importance of refugia and swimming speed in predator avoidance

The comparative vulnerability of two co-existing tadpole species (Indosylvirana temporalis and Clinotarsus curtipes) to their common predator, water scorpions (Laccotrephes sp.; Hemiptera: Nepidae), and the importance of refugia in predator avoidance were studied in the laboratory. In a total of 60 experimental trials, 10 tadpoles each of I. temporalis and C. curtipes of comparable body sizes were exposed to water scorpions (starved for 48 h). Thirty trials included refugia while 30 did not. The results of this study showed that in both the absence and the presence of refugia C. curtipes tadpoles fell prey to water scorpions more frequently than I. temporalis tadpoles. A main difference between the two species is the speed of swimming; Vmax of C. curtipes (24.73 cm/s) tadpoles is lower than that of I. temporalis (30.78 cm/s) tadpoles. This is likely to be the reason why more C. curtipes tadpoles were preyed upon than were I. temporalis tadpoles. Predation risk of tadpoles of both species was affected significantly by the presence of refuge sites. The vulnerability of both tadpole species was lower where refuge sites were available. The present study clearly shows that I. temporalis tadpoles avoid predation by water scorpions more effectively than do C. curtipes tadpoles.

The Geometry of Representational Drift in Natural and Artificial Neural Networks

Neurons in sensory areas encode/represent stimuli. Surprisingly, recent studies have suggest that, even during persistent performance, these representations are not stable and change over the course of days and weeks. We examine stimulus representations from fluorescence recordings across hundreds of neurons in the visual cortex using in vivo two-photon calcium imaging and we corroborate previous studies finding that such representations change as experimental trials are repeated across days. This phenomenon has been termed "representational drift". In this study we geometrically characterize the properties of representational drift in the primary visual cortex of mice in two open datasets from the Allen Institute and propose a potential mechanism behind such drift. We observe representational drift both for passively presented stimuli, as well as for stimuli which are behaviorally relevant. Across experiments, the drift most often occurs along directions that have the most variance, leading to a significant turnover in the neurons used for a given representation. Interestingly, despite this significant change due to drift, linear classifiers trained to distinguish neuronal representations show little to no degradation in performance across days. The features we observe in the neural data are similar to properties of artificial neural networks where representations are updated by continual learning in the presence of dropout, i.e. a random masking of nodes/weights, but not other types of noise. Therefore, we conclude that a potential reason for the representational drift in biological networks is driven by an underlying dropout-like noise while continuously learning and that such a mechanism may be computational advantageous for the brain in the same way it is for artificial neural networks, e.g. preventing overfitting.

Self-Selected Motivational Music Enhances Physical Performance in Normoxia and Hypoxia in Young Healthy Males

Humans exposed to hypoxia are susceptible to physiological and psychological impairment. Music has ergogenic effects through enhancing psychological factors such as mood, emotion, and cognition. This study aimed to investigate music as a tool for mitigating the performance decrements observed in hypoxia. Thirteen males (mean ± SD; 24 ± 4 years) completed one familiarization session and four experimental trials; (1) normoxia (sea level, 0.209 FiO2) and no music; (2) normoxia (0.209 FiO2) with music; (3) normobaric hypoxia (∼3800 m, 0.13 FiO2) and no music; and (4) normobaric hypoxia (0.13 FiO2) with music. Experimental trials were completed at 21°C with 50% relative humidity. Music was self-selected prior to the familiarization session. Each experimental trial included a 15-min time trial on an arm bike, followed by a 60-s isometric maximal voluntary contraction (MVC) of the biceps brachii. Supramaximal nerve stimulation quantified central and peripheral fatigue with voluntary activation (VA%) calculated using the doublet interpolation method. Average power output (W) was reduced with a main effect of hypoxia (p = 0.02) and significantly increased with a main effect of music (p = 0.001). When combined the interaction was additive (p = 0.87). Average MVC force (N) was reduced in hypoxia (p = 0.03) but VA% of the biceps brachii was increased with music (p = 0.02). Music reduced subjective scores of mental effort, breathing discomfort, and arm discomfort in hypoxia (p &lt; 0.001). Music increased maximal physical exertion through enhancing neural drive and diminishing detrimental mental processes, enhancing performance in normoxia (6.3%) and hypoxia (6.4%).

The Neglected Angio-Neurotrophic Parasite Gurltia Paralysans (Nematoda: Angiostrongylidae): Northernmost South American Distribution, Current Knowledge, and Future Perspectives

Gurltia paralysans is a rare metastrongyloid nematode in South America that has begun to gain relevance in feline internal medicine as a differential diagnosis of progressive degenerative myelopathy disorders. The parasite life cycle has not been fully elucidated but probably involves invertebrate gastropod fauna as obligate intermediate hosts; thus, G. paralysans remaining an extremely neglected parasitosis. Feline gurltiosis intra vitam diagnosis is highly challenging due to lack of evidence in the excretion of G. paralysans eggs and larvae, neither in feces nor in other body secretions because environmental stages and the transmission route of the parasite remain unknown. Unfortunately, no experimental trials for the treatment of feline gurltiosis have been conducted to date. However, there are some reports of the successfully antiparasitic drugs used with different effectiveness and clinical improvement results in diagnosed cats. Further studies are needed to evaluate the parasite occurrence among domestic cats and the neotropical wild felid species distributed within Colombia in addition to the gastropod fauna that may harbor the developing larvae (L1–L3) stages of this underestimated parasite.