AppliedChem, Volume 2, Issue 4 (December 2022) – 5 articles

A hot spring is a hot water source that naturally occurs on the surface of the Earth from underground; it is typically heated by subterranean volcanic activity and the local underground geothermal gradient. There are four main hot springs in Rwanda, such as: Kalisimbi, Bugarama, Kinigi, and Nyamyumba, formerly named Gisenyi hot springs. It is often believed that soaking in a hot spring is a great way to naturally detox human skin. This research focuses on the geochemical analysis of Nyamyumba hot springs, located near the fresh water supply of Lake Kivu, with the purpose of understanding its healing capacity and safety. The Nyamyumba hot springs are located in the western branch of the East African Rift System, near the Virunga volcanic complex, which explains the rising and heating mechanism of the water. The concentrations of sulfate, iron, ammonia, silica, and phosphate, and the conductivity, alkalinity, and salinity of the water were measured using standard procedures. The results showed that the hot spring water has higher concentrations of chemicals compared to the Lake Kivu water, and the geochemistry of these hot springs may be associated with rock dissolution by hot water. The measured parameters were compared with World Health Organization (WHO) standards for recreational waters, and it has been identified that the Nyamyumba hot springs are safe to use for swimming and therapeutic activities. Full article

Phytochemicals are versatile plant secondary metabolites with therapeutic properties. In this review, we explore lemongrass’s phytochemistry and pharmacological potential (Cymbopogon) as well as its impact on gut microbiota. Lemongrass is well-known for its antioxidant, anti-microbial, anti-inflammatory, anti-hypertensive, anti-diabetic, anti-mutagenicity, anxiolytic properties, and for its hypoglycemic and hypolipidemic activities. Therefore, it is widely used in pharmaceuticals, food, feed, and the cosmetics industry. Lemongrass contains phenolic metabolites (including phenolic acids, flavonoids, stilbenes, and lignans), terpenoids, and alkaloids, which are potent bioactive ingredients. Lemongrass is a precious medicinal plant. Furthermore, lemongrass phytochemicals are considered potential agents to improve health by establishing a balanced gut ecosystem. Lemongrass is considered a quintessential food and feed additive at the industrial level, since there are no issues with residue or toxins. Lemongrass powder and essential oils are used to modulate the gut ecosystem by generating anti-microbial, anti-inflammatory, and antioxidant responses, increasing the optimum nutrient absorption in the gut system. This review will further explore lemongrass’s phytochemical, pharmacological, and therapeutic potential. Full article

Group contribution (GC) methods to predict thermochemical properties are eminently important to process design. We report on a GC parametrization for the heat of formation of organic molecules exhibiting chemical accuracy, i.e., a maximum 1 kcal/mol (4.2 kJ/mol) difference between experimental and model values, whilst having a minimum number of parameters to avoid overfitting. We report an extension of recent findings to chloro-alkanes, fluoro-hydrocarbons, benzylhalides, nitro-alkanes, and acetals. Compared to the existing literature, we obtained a superior model exhibiting chemical accuracy, with exceptions when the inherent GC assumption on linearity and additivity is not valid. Moreover, to have a reliable method and not only a low absolute average deviation as reported in most publications, we accepted no or exceptionally few outliers. The example of the 1,3-dioxolane acetals revealed that by adopting the appropriate size of a group representing the acetal leads to a model showing good accuracy. The overall conclusion of the three papers on this topic is that it is feasible to achieve chemical accuracy when using high-quality experimental data and the judicious definition of chemical groups. Despite the GC method being old, the present work shows substantial and necessary increase in performance can still be achieved. Full article

The demand for REEs is continuously increasing in the European Union due to the rapid development of high-tech applications that contain REEs, mainly those based on electrification. However, the REE supply in Europe is limited because of the exclusive production of these metals by third-world countries. The European supply/demand gap for REEs can be covered with the development of recycling technologies from secondary resources, such as REE permanent magnets. NdFeB and SmCo magnets are the two main categories of REE-containing permanent magnets. In the following work, studies focusing on the preprocessing and leaching methods in order to extract REEs were identified and discussed. Although preprocessing includes controversial steps, i.e., milling and demagnetizing, numerous studies have focused on the leaching of REEs from NdFeB magnets using either inorganic or organic solvents. Meanwhile, the literature based on Sm recovery methods from SmCo magnets has been limited. Full article

Laminaria hyperborea (Gunnerus) Foslie 1885 is a seaweed native to the North Atlantic, which is utilized in the production of alginate. Its potential as a source of bioactive lipids remains unexplored. In this study, mono- and digalactosyldiacylglycerols (MGDG and DGDG) were identified in stipe and blade from L. hyperborea for the first time. Samples were harvested off the west coast of Norway in May 2018. Lipids were extracted with chloroform:methanol (2:1, v/v) and fractionated using solid phase extraction, whereupon the fatty acid content was determined by gas chromatography-mass spectrometry. The fatty acid profile was used to predict the mass of the glyceroglycolipids. A total of 103 and 161 molecular species of MGDG, and 66 and 136 molecular species of DGDG were identified in blade and stipe, respectively, by HPLC-ESI-MS/MS. The most abundant molecular species were identified from the total ion chromatograms. According to these, MGDG(20:5/18:4, 18:4/18:4, 16:0/18:1, 14:0/18:2, 14:0/18:1) and DGDG(20:5/18:4, 16:0/18:1, 14:0/18:1) were the most abundant in blade. On the other hand, in stipe, the most abundant molecular species were MGDG (14:0/18:2, 14:0/18:1, 16:0/18:1) and DGDG (14:0/18:1). The purpose of this study is to highlight the potential application of L. hyperborea in a biotechnological context. Full article