Sesquiterpene Acids and Lactones from Inula Confertiflora with their Antibacterial Activities.

The phytochemical investigation of the leaves of Inula confertiflora, a medicinal plant endemic to Ethiopia, led to the isolation of 15 terpenoids; 1ß-hydroxy-α-costic acid (1), 3α-hydroxycostic acid (2), isotelekin (3), asperilin (4), carabrone (5), carpesioline (6), graveolide (7), inuviscolide (8), 8-epi-inuviscolide (9), 1ß,4ß-dihydroxy-5α(H)-guaia-10(14),11(13)-dien-8α,12-olide (10), isoinuviscolide (11), 4ß,10ß-dihydroxy-5α(H)-1,11(13)-guaidien-8α,12-olide (12), 4ß,10ß-dihydroxy-1ß(H)-5α(H)-guai-11(13)-en-8α,12-olide (13), 4ß,10α-dihydroxy-1ß(H)-5α(H)-guai-11(13)-en-8α,12-olide (14), 4ß,10α-dihydroxy-1α(H)-5α(H)-guai-11(13)-en-8α,12-olide (15). Herein, structural elucidation and full NMR data for compound 1 are presented for the first time. The structures were elucidated using NMR, HRESIMS, and by comparison with literature data. The relative configurations were defined by NOESY correlations and single-crystal X-ray crystallography. Herein, crystallography data of 6 and 7 were reported for the first time. The antibacterial efficacy of some of the isolated compounds was evaluated against two commonly dispersed environmental strains of Escherichia coli and Staphylococcus aureus. Compounds 1, 3, 6, 7, and 8 exhibited moderate antibacterial activities against the tested organisms. The chemotaxonomic significance of compounds is discussed.

The potential of industrial sludge and textile solid wastes for biomass briquettes with avocado peels as a binder.

Producing biomass briquettes from industrial solid wastes is a more environmentally friendly way to provide alternative energy and is essential for Ethiopia to satisfy its growing energy needs while also ensuring efficient waste management in the expansion of industrial parks. The main objective of this study is to produce biomass briquettes from a mixture of textile sludge and cotton residue using avocado peels as a binder. Textile solid waste, avocado peels, and sludge were dried, carbonized, and turned into powder to make briquettes. Briquettes made from the mixture of industrial sludge and cotton residue were combined in various ratios: 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50 with the same amount of the binder. Briquettes were then made using a hand press mold followed by sun-drying for two weeks. The moisture content, calorific value, briquette density, and burning rate of biomass briquettes ranged from 5.03 to 8.04%, 11.19 to 17.2 MJ/kg, 0.21 to 0.41 g/cm3, and 2.92 to 8.75 g/min, respectively. The results revealed that the briquette produced from a 50:50 ratio of industrial sludge to cotton residue was the most efficient. The inclusion of avocado peels as a binder enhanced the briquette's binding and heating properties. Thus, the findings suggested that mixing various industrial solid wastes with fruit wastes could be an effective means of making sustainable biomass briquettes for domestic purposes. Additionally, it can also promote proper waste management and provide young people with employment prospects.

Maximizing biodiesel production from waste cooking oil with lime-based zinc-doped CaO using response surface methodology.

Biodiesel is one of the alternative fuels, commonly produced chemically from oil and methanol using a catalyst. This study aims to maximize biodiesel production from cheap and readily available sources of waste cooking oil (WCO) and lime-based Zinc-doped calcium oxide (Zn-CaO) catalyst prepared with a wet impregnation process. The Zn-CaO nanocatalyst was produced by adding 5% Zn into the calcinated limestone. The morphology, crystal size, and vibrational energies of CaO and Zn-CaO nanocatalysts were determined using SEM, XRD, and FT-IR spectroscopy techniques, respectively. The response surface methodology (RSM), which is based on the box-Behnken design, was used to optimize the key variables of the transesterification reaction. Results showed that when Zn was doped to lime-based CaO, the average crystalline size reduced from 21.14 to 12.51 nm, consequently, structural irregularity and surface area increased. The experimental parameters of methanol to oil molar ratio (14:1), catalyst loading (5% wt.), temperature (57.5 °C), and reaction time (120 min) led to the highest biodiesel conversion of 96.5%. The fuel characteristics of the generated biodiesel fulfilled the American (ASTM D6571) fuel standards. The study suggests the potential use of WCO and lime-based catalyst as efficient and low-cost raw materials for large-scale biodiesel production intended for versatile applications.

Withanolides from Discopodium penninervium.

Discopodium penninervium is a medicinal plant endemic to Ethiopia. Its twigs extract led to the isolation of three new withanolides, discopodinolides A - C, and four known analogues. The structures of the compounds were elucidated using NMR, HRMS data analyses, and literature data. The relative configurations were defined by single-crystal X-ray crystallography and NOESY correlations. The antibacterial efficacy of the isolated compounds was evaluated against four commonly dispersed environmental strains of Escherichia coli, Bacillus subtilis, Bacillus pumilus, and Bacillus megaterium. Discopodinolides B and C exhibited moderate antibacterial activities against the pathogenic strains of E. coli, B. subtilis, and B. megaterium.

Structural Engineering of Organic D-A-π-A Dyes Incorporated with a Dibutyl-Fluorene Moiety for High-Performance Dye-Sensitized Solar Cells.

Structural engineering of the light-harvesting dyes employed in DSSCs (dye-sensitized solar cells) with a systematic choice of the electron-donating and -accepting groups as well as the π-bridge allows the (photo)physical properties of dyes to match the criteria needed for improving the DSSC efficiency. Herein, we report an effective approach of molecular engineering of DSSC sensitizers, aiming to gain insights on the configurational impact of the fluorenyl unit on the optoelectronic properties and photovoltaic performance of DSSCs. Five new organic dyes (GZ116, GZ126, GZ129, MA1116, and MA1118) with a D-A-π-A framework integrated with a fluorenyl moiety were designed and synthesized for DSSCs. The fluorenyl unit is configured as part of the π-spacer for the GZ series, whereas it connected on the electron-deficient quinoxaline motif for the MA series. The devices fabricated from the MA1116 sensitizer produced the best performance under standard AM 1.5 G solar conditions as well as dim-light (300-6000 lx) illumination. The devices fabricated from MA1116 displayed a PCE of 8.68% (Jsc = 15.00 mA cm-2, Voc = 0.82 V, and FF = 0.71) under 1 sun and 26.81% (Jsc = 0.93 mA cm-2, Voc = 0.68 V, and FF = 0.76) under 6000 lx illumination. The device efficiency based on dye MA1116 under 1 sun outperformed that based on the standard N719 dye, whereas a comparable performance between devices based on MA1116 and N719 was achieved under dim-light conditions. A combination of enhancing the charge separation, suppressing dye aggregation, and providing better insulation that prevents the oxidized redox mediator from approaching the TiO2 surface all contribute to the superior performance of DSSCs fabricated based on these light-harvesting dyes. The judicious integration of the fluorenyl unit in a D-A-π-A-based DSSC would be a promising strategy to boost the device performance.

A General Strategy to Enhance the Performance of Dye-Sensitized Solar Cells by Incorporating a Light-Harvesting Dye with a Hydrophobic Polydiacetylene Electrolyte-Blocking Layer.

A unique strategy to suppress charge recombination effectively and enhance light harvesting in dye-sensitized solar cells (DSSCs) is demonstrated by the design of a new dipolar organic dye functionalized with a diacetylene unit, which is capable of undergoing a photoinduced crosslinking reaction to generate a hydrophobic polydiacetylene layer. The polydiacetylene layer serves as an electrolyte-blocking layer that effectively blocks the approach of the oxidized redox mediator and suppresses the dark current, and also plays a role in light harvesting owing to efficient energy transfer to the dipolar dyes. A 15 % efficiency improvement was achieved on going from the monomer dye (JSC =13.5 mA cm-2 , Voc =0.728 V, fill factor=0.73, η=7.17 %) to the crosslinked dye (JSC =14.9 mA cm-2 , Voc =0.750 V, fill factor=0.74, η=8.27 %) under AM 1.5 conditions.