Biodiesel Fuel from Animal Fat. Ancillary Studies on Transesterification of Beef Tallow

Transesterification of beef tallow was investigated. The solubility of ethanol in beef tallow was much higher than that of methanol. At 100 °C the solubility of methanol was 19% (w/w). The solubility of ethanol in beef tallow reached 100% (w/w) at about 68 °C. For the distribution of methanol between beef tallow methyl esters (BTME) and glycerol, the percentage of total methanol in the glycerol phase was higher than that in the fatty acid methyl ester (FAME) phase in a simulated system at room temperature. At 65-80 °C, however, the percentage of total methanol in FAME (60% (w/w)) was higher than that in glycerol (40% (w/w)) in a 90:10 (w/w) blend of FAME and glycerol. This coincided with the methanol distribution in the transesterified product. The process for making beef tallow methyl esters should recover methanol using vacuum distillation, separate the ester and glycerol phases, and then wash the beef tallow methyl esters with warm water. At neutral pH, the separation of ester and glycerol and water washing was easier because it reduced emulsion formation

The Effects of Catalyst, Free Fatty Acids, and Water on Transecterification of Beef Tallow

Transesterification of beef tallow and methanol is affected by many factors. Catalyst, free fatty acids, and water in beef tallow, and reaction time were investigated. Sodium hydroxide (NUOH) was a more effective catalyst than sodium methoxide (NaMeOj. NaOH and NaMeO reached their maximum activities at 0.3% and 0.5%, w/w of beef tallow, respectively. The presence of water had more negative effect on transesterification than did the presence of free fatty acids (FFA). For best results, the water content of beef tallow should be kept not beyond 0.0696, w/w. FFA content of beef tallow should be kept below 0.596, w/w. The transesterification of beef tallow was very slow in the first minute. The production of beef tallow methyl esters (BTME) was complete after about 15 min. There were still some mono- and diglycerides in the BTME phase after the reaction was finished

Flavour Changing Neutral Currents, Weak-Scale Scalars and Rare Top Decays

We examine the decays $t\rightarrow c\gamma$ and $c Z^0$ in the Standard Model with an extra scalar doublet and no discrete symmetry preventing tree-level flavour changing neutral currents. The Yukawa couplings of the new scalars are assumed to be proportional to fermion masses, evading bounds on FCNC's from the light quark sector. These rare top decays may be visible at the SSC.Comment: (some wording changed, and several references added) 13 pages, 2 figures included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-0

Investigation of particle radiation and its effect on NO prediction in a pilot-scale facility for both air and oxy-coal combustion

Radiation heat transfer plays an important role in pulverised coal combustion, influencing the overall combustion efficiency, pollutant formation and flame ignition and propagation. In this paper, the radiation properties of the particles as well as gas property models on the overall influence of the prediction of the formation of NOx pollutants in a pulverised coal combustion have been investigated. The non-grey weighted sum of grey gases (WSGG) model has been employed to calculate the radiation of the gas phase coupled with the radiation interaction from the particulate phase. The Mie theory, as well as constant or linear models, have been employed to describe the particle radiative properties. The prediction results, calculated from the data from a 250 kW pilot scale combustion test facility (CTF), are compared against experimental measurements under air-fired condition and a range of oxyfuel conditions. The results show that the choice of radiation solution can have a considerable impact on the radiative heat transfer results, in which the Mie theory shows a significant improvement in the incident wall heat flux compared to the constant or linear models. Also, the more accurate solution employed for radiation of gases and particles considerably improves the NOx prediction in the flame region

The role of insulin receptor substrate 2 in hypothalamic and beta cell function

Insulin receptor substrate 2 (Irs2) plays complex roles in energy homeostasis. We generated mice lacking Irs2 in beta cells and a population of hypothalamic neurons (RIPCreIrs2KO), in all neurons (NesCreIrs2KO), and in proopiomelanocortin neurons (POMCCreIrs2KO) to determine the role of Irs2 in the CNS and beta cell. RIPCreIrs2KO mice displayed impaired glucose tolerance and reduced P cell mass. Overt diabetes did not ensue, because beta cells escaping Cre-mediated recombination progressively populated islets. RIPCreIrs2KO and NesCreIrs2KO mice displayed hyperphagia, obesity, and increased body length, which suggests altered melanocortin action. POMCCreIrs2KO mice did not display this phenotype. RIPCreIrs2KO and NesCreIrs2KO mice retained leptin sensitivity, which suggests that CNS Irs2 pathways are not required for leptin action. NesCreIrs2KO and POMCCreIrs2KO mice did not display reduced beta cell mass, but NesCreIrs2KO mice displayed mild abnormalities of glucose homeostasis. RIPCre neurons did not express POMC or neuropeptide Y. Insulin and a melanocortin agonist depolarized RIPCre neurons, whereas leptin was ineffective. Insulin hyperpolarized and leptin depolarized POMC neurons. Our findings demonstrate a critical role for IRS2 in beta cell and hypothalamic function and provide insights into the role of RIPCre neurons, a distinct hypothalamic neuronal population, in growth and energy homeostasis

Automated metamorphic testing on the analyses of feature models

Copyright © 2010 Elsevier B.V. All rights reserved.Context: A feature model (FM) represents the valid combinations of features in a domain. The automated extraction of information from FMs is a complex task that involves numerous analysis operations, techniques and tools. Current testing methods in this context are manual and rely on the ability of the tester to decide whether the output of an analysis is correct. However, this is acknowledged to be time-consuming, error-prone and in most cases infeasible due to the combinatorial complexity of the analyses, this is known as the oracle problem.Objective: In this paper, we propose using metamorphic testing to automate the generation of test data for feature model analysis tools overcoming the oracle problem. An automated test data generator is presented and evaluated to show the feasibility of our approach.Method: We present a set of relations (so-called metamorphic relations) between input FMs and the set of products they represent. Based on these relations and given a FM and its known set of products, a set of neighbouring FMs together with their corresponding set of products are automatically generated and used for testing multiple analyses. Complex FMs representing millions of products can be efficiently created by applying this process iteratively.Results: Our evaluation results using mutation testing and real faults reveal that most faults can be automatically detected within a few seconds. Two defects were found in FaMa and another two in SPLOT, two real tools for the automated analysis of feature models. Also, we show how our generator outperforms a related manual suite for the automated analysis of feature models and how this suite can be used to guide the automated generation of test cases obtaining important gains in efficiency.Conclusion: Our results show that the application of metamorphic testing in the domain of automated analysis of feature models is efficient and effective in detecting most faults in a few seconds without the need for a human oracle.This work has been partially supported by the European Commission(FEDER)and Spanish Government under CICYT project SETI(TIN2009-07366)and the Andalusian Government project ISABEL(TIC-2533)

Tie-2 regulates the stemness and metastatic properties of prostate cancer cells.

Ample evidence supports that prostate tumor metastasis originates from a rare population of cancer cells, known as cancer stem cells (CSCs). Unfortunately, little is known about the identity of these cells, making it difficult to target the metastatic prostate tumor. Here, for the first time, we report the identification of a rare population of prostate cancer cells that express the Tie-2 protein. We found that this Tie-2High population exists mainly in prostate cancer cell lines that are capable of metastasizing to the bone. These cells not only express a higher level of CSC markers but also demonstrate enhanced resistance to the chemotherapeutic drug Cabazitaxel. In addition, knockdown of the expression of the Tie-2 ligand angiopoietin (Ang-1) led to suppression of CSC markers, suggesting that the Ang-1/Tie-2 signaling pathway functions as an autocrine loop for the maintenance of prostate CSCs. More importantly, we found that Tie-2High prostate cancer cells are more adhesive than the Tie-2Low population to both osteoblasts and endothelial cells. Moreover, only the Tie-2High, but not the Tie-2Low cells developed tumor metastasis in vivo when injected at a low number. Taken together, our data suggest that Tie-2 may play an important role during the development of prostate tumor metastasis.published_or_final_versio

Large eddy simulation of a coal flame: estimation of the flicker frequency under air and oxy-fuel conditions

Fossil fuel combustion, such as coal combustion, currently meets the majority of the global energy demand; however, the process also produces a significant proportion of the worldwide CO2 greenhouse gas emissions. Further improvement in the efficiency and control of the combustion process is needed, as well as the implementation of novel technologies such as carbon capture and storage (CCS). Oxy-fuel combustion is a very promising CCS technology, where the air in the combustion process is replaced with a mixture of recycled flue gas and oxygen producing a high CO2 outflow that can effectively be processed or stored. The adjustment of the combustion environment within the boiler resulting from the high CO2 concentration will modify the flame characteristics. It is therefore important to evaluate properly the changes of the flame that occur with different flue gas recycle schemes. A coal flame is often characterised by its physical parameters, such as the flame size, shape, brightness and temperature, and it can be considered as a stable flame by the presence of ignition and the propagation of the flame. The oscillatory behaviour of a flame can be quantified by the flicker frequency obtained after the instantaneous variations of the flame parameters, and is used as a reference for flame stability. Computational Fluid Dynamics (CFD) is widely used to model coal combustion. This work compares the estimated flicker frequency taken from CFD calculations against measurements undertaken at the experimental facilities of the UKCCSRC Pilot-scale Advanced Capture Technology (PACT) located in South Yorkshire, UK. The 250 kW combustion test facility consists of a down-fired, refractory lined cylindrical furnace, which is 4 m in height with a 0.9 m internal diameter. The furnace is fitted with a scaled version of a commercially available Doosan Babcock low-NOx burner. The flame physical parameters are approximated from performing a Large Eddy Simulation (LES) using the CFD code ANSYS FLUENT v15. The flicker frequency obtained from the CFD approach is compared against the experimentally measured value from a 2D flame imaging system. A series of oxy-fuel cases are then examined in the same fashion in order to assess their flame stability and the boiler operational limit. The flicker frequency trend obtained from the computations and measurements helps to determine the dynamic response of the flame for different combustion environments, and the results will be applicable in determining the optimal recycle ratio applied in future oxy-fuel systems

Managing software development information in global configuration management activities

Software Configuration Management (SCM) techniques have been considered the entry point to rigorous software engineering, where multiple organizations cooperate in a decentralized mode to save resources, ensure the quality of the diversity of software products, and manage corporate information to get a better return of investment. The incessant trend of Global Software Development (GSD) and the complexity of implementing a correct SCM solution grow not only because of the changing circumstances, but also because of the interactions and the forces related to GSD activities. This paper addresses the role SCM plays in the development of commercial products and systems, and introduces a SCM reference model to describe the relationships between the different technical, organizational, and product concerns any software development company should support in the global market