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Abstract Transesterification of triglycerides (oils and fats) catalyzed by bases is a common method for production of fatty acid methyl esters (FAME) – a renewable fuel (biodiesel) and basic oleochemical. Hydrolysis of esters – saponification – represents the main side reaction. Saponification leads to catalyst deactivation and impedes products purification. In this work, kinetics of the competing triglyceride hydrolysis and methanolysis (i.e. transesterification) is investigated. Furthermore, an alternative organic catalyst – tetramethylammonium hydroxide (TMAH) – is compared with potassium hydroxide and sodium methoxide. TMAH is less active but the methanolysis is more selective towards FAME formation and hydrolysis proceeds at a slower rate in comparison to the inorganic catalysts. FAME are less susceptible to hydrolysis than glycerides. A simple mathematical model assuming irreversibility of all reactions is capable to describe the measured data well (40–60 °C, TMAH concentration 0.5–1.5 w TMAH /w oil , molar ratio methanol:oil = 6).

Abstract An electrolyte solution of Lithium Bromide (LiBr) water was chosen for study because of its wide use in prototype absorption machines. The LiBr must be operated close to the temperature and mass fraction at which lithium bromide achieves the highest efficiency. For the purpose of establishing the concentration in a prototype absorption machines, measurements were made of the properties that vary with temperature and concentration. The selected properties are electrical conductivity, density, refractive indexes and sound velocity. The resulting measured properties values were compared with some values found in previous works. The properties of aqueous lithium bromide solutions were measured at the concentration range of 45–65% of LiBr and temperatures range of 20–80 °C. Semi-empirical correlations that determine the properties of lithium bromide are also proposed. The methods for measuring the properties of aqueous solutions were considered taking into account their reliability, simplicity and sampling time.

We censused primate populations at three non-hunted ‘terra firme’ forests of south-eastern Colombian Amazonia. The aggregate biomass densities of diurnal primates at all sites were amongst the lowest recorded for any non-hunted forest in western Amazonia and elsewhere in the Neotropics. Densities of red howler monkeys were low, as is typical in Amazonian terra firme forests far removed from white-water rivers, and densities of woolly monkeys were 1.5–3.5 times lower than those estimated for this species in central-western Brazilian Amazonia. Densities of small to mid-sized primates except for brown capuchins (Cebus apella) and white-faced capuchins (Cebus albifrons) were similar to those of other oligotrophic Amazonian forest sites. Our results are in agreement with other studies showing that terra firme forests of lowland Amazonia typically sustain a low biomass density of primates and other mid-sized to large vertebrates. Large reserves are therefore required to assure the viability of primate populations in oligotrophic systems. Given the escalating negative impacts of human habitat disturbance and hunting in Colombian Amazonia, we urge that a baseline sampling protocol to quantify the abundance and distribution of the harvest-sensitive vertebrate fauna be established within protected areas and the large indigenous reserves so that conservation efforts can be defined and implemented.

Abstract Liquefied Natural Gas (LNG) is becoming vital in relation to energy transition and fighting climate change. Because of its cryogenic temperature (111 K), LNG is an exergy “mine” that can be exploited in the regasification process for multiple industrial applications. But this exergy is usually wasted. This research presents a Combined Cold and Power (CCP) system with exergy recovery from LNG-regasification. This exergy is exploited for the combined production of electricity and low-temperature refrigeration distributed through a CO 2 District Cooling Network. These systems entail many benefits, but also pending challenges. The CCP system is modelled using real operation data, and its performance is analyzed and benchmarked against that of a cryogenic power plant, both at design and off-design operating conditions. The proposed CCP system reports an equivalent electricity saving of 139 kWh/t-LNG with an exergetic efficiency of 40%, turning into useful energy up to 64% of the maximum cold recoverable in the regasification process. The performance enhances as the heat source temperature rises. Higher LNG flow rates contribute to increase the electricity and refrigeration production, but irreversibilities also increase. Finally, findings show that a low LNG regasification pressure is preferable in spite of the negative effect on the power generation.

AbstractThe international building sector plays an important role on energy policy and reduction of CO2 emissions. The focus of energy conservation has started from building level and nowadays expands to district, city, region or national level. In this study, an overview, performed within the European project Sinfonia for preparation of a new district tool with focus on energy conservation, will be presented about existing district tools. Several aspects of the tools were included in the overview, such as focus, aim, analytical approach, methodology, geographical coverage, required input data, commercial/freeware, source code, language, tool status, organization/project developing the tool, and web link. The main components of energy district tools such as 3D geographical data, data for building features and properties, and simulation methods were also addressed.Additionally, the issue of appropriate boundary conditions on urban energy analysis, such as user behaviour, will be discussed. A simulation study of a dwelling in various energy standards including different occupant scenarios was performed, and as a result, a formula was developed to estimate an equivalent heating reference temperature as a function of building envelope, living area, and outdoor temperature. Thus, the estimated equivalent heating reference temperature can be used as input in district energy simulations, instead of a constant set point value independent of the building.The present study can serve as a basis for new or further development of tools trying to cover the gap and the limits of the existing ones.

Abstract The chemical equilibrium of gasification systems is modeled using one of two approaches, the stoichiometric (S) or the non-stoichiometric (NS) method. A complete survey of the gasification literature shows that about half of equilibrium modeling studies use either just the S, or just the NS method, and do not consider whether a different model choice would lead to a different solution. The remaining half of equilibrium modeling studies does motivate their model choice. Among those that discuss their model choice roughly half (15/27) state that the two approaches produce identical solutions. The remaining half propose that the NS method yields superior results (10/27), or the S method may yield superior results (2/27), and thus imply that the methods are not necessarily equivalent. The contradictory conjectures on both sides are made without definitive proof, or reference to definitive proof or evidence. In addition to providing a concise technical review of this question and its role in biomass gasification modeling, a second goal of this technical review article is to provide a tractable, yet rigorous and definitive exposition of the mathematical proof that the stoichiometric and non-stoichiometric approaches are equivalent methods for computing the equilibrium composition of the core gasification problem. This should provide perspective on the existing literature, and helpful guidance for future modeling work. Although the technical review and analysis provided here settles a longstanding contradiction in the gasification literature the relevant proof applies to any reactive system. The systematic template for S vs NS equivalence provided here should therefore be equally useful to researchers modeling and simulating the equilibrium of any other reactive system, since there is always the need to choose between the S or NS approach.

This paper is a further study of ion binding to protein surfaces and builds on the studies of the binding of [Cr(CN)6]3− and [Fe(edta)(H2O)]− previously reported [Williams et al. (1982) FEBS Lett. 15, 293–299; Eley et al. (1982) Eur. J. Biochem. 124, 295–303]. In the present paper the binding of polyaminocarboxylate complexes of gadolinium have been studied. Eight ion‐binding sites have been identified on the surface of cytochrome c. These exhibit different binding specificities which, in some cases, are not fully understood. However it is clear that simple outer‐sphere interactions are not the sole determining factor for the association of metal ion complexes with proteins. The NMR paramagnetic difference spectrum method has been shown to be good at locating binding sites and revealing qualitative differences in their relative affinities for a range of complex types. However the use of relaxation probes is not a good method for the quantitative determination of binding constants; for this, isostructural shift probes must be sought.

AbstractThe assignment of the crystallographic axes for the hole momentum‐space wave function maps shown in Fig. 2 of Reuter et al., phys. stat. sol. (b) 243, 3942 (2006) has been corrected. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A novel protocol for the synthesis of complex framework compounds containing a VCP fragment is presented by means of UV conversion of CP derivatives at r.t., providing high yields of target products in an unprecedented atom economical reversible step.