A New Sesquiterpene Essential Oil from the Native Andean Species Jungia rugosa Less (Asteraceae): Chemical Analysis, Enantiomeric Evaluation, and Cholinergic Activity

As part of a project devoted to the phytochemical study of Ecuadorian biodiversity, new essential oils are systematically distilled and analysed. In the present work, Jungia rugosa Less (Asteraceae) has been selected and some wild specimens collected to investigate the volatile fraction. The essential oil, obtained from fresh leaves, was analysed for the first time in the present study. The chemical composition was determined by gas chromatography, coupled to mass spectrometry (GC-MS) for qualitative analysis, and to flame ionization detector (GC-FID) for quantitation. The calculation of relative response factors (RRF), based on combustion enthalpy, was carried out for each quantified component. Fifty-six compounds were identified and quantified in a 5% phenyl-polydimethylsiloxane non-polar column and 53 compounds in a polyethylene glycol polar column, including four undetermined compounds. The main feature of this essential oil was the exclusive sesquiterpenes content, both hydrocarbons (74.7% and 80.4%) and oxygenated (8.3% and 9.6%). Major constituents were: γ-curcumene (47.1% and 49.7%) and β-sesquiphellandrene (17.0% and 17.9%), together with two abundant undetermined oxygenated sesquiterpenes, whose abundance was 6.7–7.2% and 4.7–3.3%, respectively. In addition, the essential oil was submitted to enantioselective evaluation in two β-cyclodextrin-based enantioselective columns, determining the enantiomeric purity of a minor component (1S,2R,6R,7R,8R)-(+)-α-copaene. Finally, the AChE inhibition activity of the EO was evaluated in vitro. In conclusion, this volatile fraction is suitable for further investigation, according to two main lines: (a) the purification and structure elucidation of the major undetermined compounds, (b) a bio-guided fractionation, intended to investigate the presence of new sesquiterpene AChE inhibitors among the minor components.

High precision evaluation of the combustion enthalpy by ab-intio computations

Accurate evaluation of combustion enthalpy is of high scientific and industrial importance. Although via ab-initio computation of heat of reactions, as one of the promising and well-established approaches in computational chemistry, this goal should in principle be achievable, examples of reliable and precise evaluation of heat of combustion by ab-initio methods has surprisingly not yet been reported. A handful of works carried out for this purpose report significant inconsistencies between the ab-initio evaluated and experimentally determined combustion enthalpies and suggest empirical corrections to improve the accuracy of predicted data. With this background, the main aims of the present study is to investigate the reasons behind those reported inconsistencies and propose guidelines for highly accurate evaluation of combustion enthalpy via ab-initio computations. Through the provided guidelines, the most accurate results ever reported, with average absolute deviation, mean unsigned error and correlation coefficient of 1.556 kJ/mole, 0.072% and 0.99999, respectively, is achieved for theoretically computed combustion enthalpies of 40 studied hydrocarbons.

Achieving Sustainable Energy Security in Indonesia Through Substitution of Liquefied Petroleum Gas with Dimethyl Ether as Household Fuel

Indonesia has been facing an energy security issue regarding Liquefied Petroleum Gas (LPG) consumption. The rapid increase of LPG consumption and huge import have driven the Indonesian government to develop the alternative for LPG in the household sector. Dimethyl ether (DME) is the well-fit candidate to substitute LPG because of its properties similarities. However, discrepancies in the properties, such as combustion enthalpy and corrosivity, lead to adjustments in the application. Coal is a potential raw material to produce DME, especially in Indonesia, known as the fourth-largest coal producer globally. However, the gasification of coal into DME brings a problem in its sustainability. To compensate for the emission, co-processing of DME with biomass, especially from agricultural residue, has been discovered. Recently, carbon dioxide (CO2) captured from the gasification process has also been developed as the raw material to produce DME. The utilization of CO2 recycling into DME consists of two approaches, methanol synthesis and dehydration reactions (indirect synthesis) and direct hydrogenation of CO2 to DME (direct synthesis). The reactions are supported by the catalytic activity that strongly depends on the metal dispersion, use of dopants and the support choice. Direct synthesis can increase the efficiency of catalysts used for both methanol synthesis and dehydration. This paper intended to summarize the recent advancements in sustainable DME processing. Moreover, an analysis of DME's impact and feasibility in Indonesia was conducted based on the resources, processes, environmental and economic aspects. Keywords: coal gasification, DME, energy security, LPG, sustainable

Precious Data from Tiny Samples: Revealing the Correlation Between Energy Content and the Chemical Oxygen Demand of Municipal Wastewater by Micro-Bomb Combustion Calorimetry

Wastewater treatment plants (WWTP) are aimed to be transformed from sinks into sources of energy and material. For fostering corresponding engineering efforts and economic assessments, comprehensive knowledge of the energy content of wastewater is required. We show in this proof-of-concept study that these data can be gathered by combining micro-bomb combustion calorimetry with freeze-drying. Thereby, the methodology for measuring the combustion enthalpy (ΔcH) of wastewater is significantly improved by decreasing the time demand for the drying process as only tiny amounts of samples are required. Here, the effluent of the primary clarifier of a wastewater treatment plant treating low-strength municipal wastewater was sampled on a weekly basis for 1 year, yielding 53 composite samples that were analyzed for ΔcH and standard wastewater parameters. A robust correlation between the chemical oxygen demand (COD) and ΔcH of −14.9 ± 3.5 kJ gCOD−1 (r = 0.51) was determined, verifying previous results obtained with more laborious and time-demanding methodologies. The global chemical energy potential of the sampled WWTP is presumably higher as the first treatment steps and losses during sample preparation reduced the amount of energy-rich compounds. A stronger correlation was observed between ΔcH and the biochemical oxygen demand (BOD5, r = 0.64), suggesting its usage for predicting the potential of wastewater as feedstock for biotechnological applications. This demonstrates that micro-bomb combustion calorimetry can be applied for deriving precious information on the energy content of wastewater from simple COD measurements.

Thermodynamic properties of the 2,4,6-triamine-1,3,5-triazine dodecahydro-closo-dodecaborate

Прямым сжиганием в бомбовом калориметре KL-5 экспериментально определена удельная теплота сгорания додекагидро-клозо-додекабората 2,4,6-триамино-1,3,5-триазина, из которой рассчитаны его стандартные теплоты сгорания и образования, равные –13 359 и –807 кДж/моль соответственно. By means of the direct burning in bomb calorimeter KL-5 was obtained experimentally specific combustion enthalpy of 2,4,6-triamino-1,3,5-triazine dodecahydro-closo-dodecaborate from which were calculated their standard combustion and formation enthalpies equal –13 359 and –807 kJ/mol, respectively.

High loading rice husk green composites: Dimensional stability, tensile behavior and prediction, and combustion properties

High-fiber loading green composites were prepared from recycled high-density polyethylene (rHDPE)/recycled polyethylene terephthalate (rPET) blend matrix and rice husk (RH) as filler (from 40 wt% up to 80 wt%) via corotating twin-screw extruder and compression molding. The water absorption (WA) upon immersion in sea water, mechanical behavior, and combustion enthalpy of green composites were examined. The WA mechanisms obeyed the Fickian diffusion. The computed diffusion coefficient (D), thermodynamic solubility (S), permeability (P), and orthotropic swelling were generally increased as a function of RH filler. The increment of tensile strength and modulus of composites were maximized up to 16% and 121%, respectively, which was achieved at 70 wt% RH filler. The theoretical prediction of tensile strength and Young’s modulus from micromechanical models for random oriented RH fiber/blend composites were compared with the experimental results. As the RH weight fraction increased, the combustion enthalpy decreased (by approximately 30–48%) and thereby the enhancing the fire retardancy of green composite.

Empirical method for predicting the enthalpy changes of combustion of amides

The enthalpy change of combustion is one of the basic thermochemical characteristics of an organic compound, indicating the amount of heat produced in the complete combustion of the substance. The enthalpy changes of combustion of many organic compounds have been experimentally determined. Hitherto, the existing empirical approaches have aimed at calculating the combustion enthalpy change of individual classes only, which do not always satisfactorily agree with the experimental results. Therefore, the method of correlation?regression analysis is proposed herein to establish the combustion enthalpy changes of previously unexplored compounds. As is known, a linear relationship between two characteristics is possible only if both of them obey the principle of additivity, i.e., in a homologous series of organic compounds with increasing number of CH2-groups, the value of additive characteristic (for example, the enthalpy change of vaporization) should increase by a certain constant amount.