University of Maroua

This study presents an integrated geotechnical, mineralogical and geochemical characterization of clayey Vertisols developed under Sudano-Sahelian climatic conditions in northern Cameroon, with the aim to provide a scientific basis for future stabilization and engineering applications. Representative Vertisol samples were collected from the North and Far North regions and investigated using standard geotechnical tests, chemical analyses, and mineralogical identification by X-ray diffraction. The results reveal clay-rich materials dominated by fine fractions, with textures ranging from sandy clay to sandy heavy clay, and displaying low to high plasticity indices, reflecting strong smectitic influence. Geochemically, the Vertisols are characterized by high SiO₂ and Al₂O₃ contents, moderate to high Fe₂O₃ levels, elevated CIA values (57–83%), and significant cation exchange capacities, indicating advanced chemical weathering under seasonally contrasted tropical conditions. Mineralogical assemblages are composed by smectite, kaolinite, illite, quartz and K-feldspars, confirming both pedogenetic clay formation and inheritance from parent materials. These combined characteristics explain the pronounced shrink–swell behavior and vertic features observed in the field. Overall, the studied Vertisols exhibit physicochemical properties that make them promising raw materials for sustainable construction applications and environmental uses, if appropriate stabilization strategies are implemented to mitigate their expansive behavior.

Activated Carbon derived from the bones of Bos Indicus Gudali (ACB) is introduced in this study as a novel and environmentally friendly option for the adsorption of Crystal Violet dye (CV) from water. Various characterization techniques, including semiquantitative X-ray analysis, X-ray diffraction, Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (ATR–FTIR), and Point of Zero Charge (pHPZC), were employed to analyze the bone pyrolysis process. The study investigated how various factors such as the mass of the adsorbent, the initial pH of the solution, contact time, initial dye concentration, and temperature influence the batch adsorption process. Kinetic data were examined using several models including Intra-particle diffusion, Elovich, Pseudo-first-order, and Pseudo-second-order. The findings indicated that the Pseudo-second-order model accurately captured the kinetics of CV adsorption onto ACB. For the isothermal data analysis, the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were employed. The equilibrium data for CV adsorption onto ACB fit the Langmuir isotherm model most effectively, revealing a maximum adsorption capacity of 17.331 mg g−1 at 303 K. Moreover, the Dubinin-Radushkevich model suggested that the nature of the adsorption was physical. The thermodynamic analysis confirmed that the adsorption process was physical, spontaneous, and exothermic.

Using the framework of noncommutative geometry, specifically the concepts of symplectic structure and the Weyl product, unitary representations of the Galilei group are constructed with the operators [Formula: see text] and [Formula: see text]. This formulation allows the Schrödinger equation to be expressed in phase space, where the quark–antiquark interaction is modeled using the Hulthen potential plus a linear term. However, direct application of this potential to meson spectroscopy presents certain challenges in the context of Moyal quantization. To address these difficulties, a methodological approach based on the Levi-Civita transformation is introduced to derive the mass spectrum of bound states. The results of these calculations are then applied to the study of several heavy mesons, including charmonium [Formula: see text], bottomonium [Formula: see text] and the mixed-flavor meson [Formula: see text], as well as heavy-light mesons such as [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. The analysis is restricted to S-wave states, as our theoretical model is found to be applicable primarily to such configurations. A key insight of our approach is that the Levi-Civita transformation naturally leads to quark confinement within mesons. Furthermore, the calculated meson masses exhibit good agreement with experimental data, reinforcing the validity of the method. The Wigner functions of the studied mesons are also analyzed. It is observed that they exhibit negative values in the first excited state, whereas they remain strictly positive in the ground state.

Long-lasting insecticidal nets (LLINs) are crucial for malaria prevention in Cameroon, yet their operational performance may be compromised because of deterioration of the physical integrity and bioefficacy of nets. This study evaluated LLINs, physical integrity, and bioefficacy following mass distribution campaigns in two regions in Cameroon: East (Bertoua) and Centre (Eyang). Household surveys were conducted to assess ITN ownership, usage patterns, and maintenance practices. Net condition was measured using the proportionate hole index (pHI), and bio-efficacy was assessed using WHO cone bioassays against Anopheles gambiae (s.s.) (Kisumu strain) and local field mosquitoes. A total of 55 LLINs from Bertoua and 30 from Eyang were sampled. LLIN ownership was comparable between sites (66.7% in Bertoua vs. 67.9% in Eyang), with a higher usage rate in Bertoua (73.3%) compared to 58.2% in Eyang. In Bertoua, a large percentage of LLINs (59.6%) were too torn, with Olyset Plus being the most common brand. In contrast, Eyang had a lower proportion of torn nets (44%), and households used a combination of different brands, including the Olyset net, Permanet 2.0, and Royal Sentry. Against the susceptible Kisumu strain, Bertoua's Olyset Plus nets showed optimal efficacy with a 94.6% mortality rate, exceeding the World Health Organization's (WHO) threshold of ≥ 80%. In contrast, nets from Eyang had a 79.3% mortality rate, falling short of the optimal threshold. However, when tested against local field mosquitoes, Olyset Plus (pyrethroid + PBO) showed higher efficacy (mortality rate of 31.8%) than the other brands (7.1% from Olyset net; 18.6% for Permanet 2.0; and 8.6% for Royal Sentry) (p > 0.0001). These findings underscore the crucial importance of proper LLINs maintenance, particularly regarding washing practices. The results also indicate the need to deploy newer generation LLINs to address emerging insecticide resistance and strengthen malaria control efforts.

ABSTRACT Climate change is reshaping society's moral expectations of business corporations. Its increasing threat to ecological stability and intergenerational well‐being has propelled corporations, once viewed solely as economic entities, into the forefront of climate‐justice debates. This Advanced Review surveys scholarly developments, mainly from the early 2000s to 2025, on the ethical principles, institutional structures, and practical performance of corporate climate responsibility. Focusing on traditional distributive factors, such as causality and capacity, along with the emerging importance of collaboration, the article examines how the literature addresses corporate responsibility in climate issues. It differentiates between corporations as secondary justice agents or market‐driven actors, whose duties involve mitigation, and primary agents or political actors, tasked with influencing regulations, advocating responsibly, and addressing systemic inequalities. The review clarifies the spectrum of interventions and evaluation metrics while exploring conflicts between profit motives and sustainability. It concludes by outlining a future research agenda at the intersection of political philosophy, business ethics, and climate ethics. This article is categorized under: Climate, Nature, and Ethics > Ethics and Climate Change Climate, Nature, and Ethics > Climate Change and Human Rights Climate, Nature, and Ethics > Climate Change and Global Justice