Search

Background: Urea is a fertilizer widely used by farmers, especially vegetable farmers, due to its high nitrogen content, around 46 %. However, plants only use a small amount of nitrogen, a maximum of 35 %, while the remaining nitrogen is wasted and released into the environment. Undeniably, it causes increases production costs and environmental problems. A slow-release urea fertilizer (SRF) has been formulated to resolve these issues., Methods: In this study, the membrane was made of chitosan with several crosslinking agents such as Tripolyphosphate (TPP). In addition, calcium ion bonds are expected to increase the interaction with urea fertilizer through the encapsulation process., The Results: Our data showed that urea slow-release fertilizer (SRF) with the chitosan/TPP/Ca membrane, was successfully synthesized. This membrane has the characteristics of a thin white layer that is transparent. The physical and chemical characterization of SRF membranes with various coating membrane variations showed that the chitosan/TPP/Ca-urea membrane has Young's modulus of 7.75-22.05 N/mm2, swelling of 109.52-132.62 % and porosity of 0.756-1.06 %. Functional group analysis shows that several spectral changes indicate the presence of crosslinking process between the chitosan functional groups and TPP. The urea release results show that the membrane is released through a diffusion mechanism. Furthermore, SEM results show that these membranes have pores with various shapes and sizes., Conclusion: Based on the result, it can be concluded that chitosan membrane modification with the addition of TPP and calcium oxide provides improved membrane characteristic cs including degree of development, hydrophobicity, membrane stress, and nitrogen release on the membrane. This membrane shows is indicating suitability as a slow-release fertilizer., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Sari Edi Cahyaningrum reports financial support was provided by State 10.13039/501100012696University of Surabaya. Sari Edi Cahyaningrum reports a relationship with State University of Surabaya that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Three novel dihydrochalcones, flemilineatins C-E ( 1-3 ), and two known flavanones ( 4-5 ) were isolated from Flemingia lineata (L.) W.T. Aiton leaves. Dihydrochalcones 1-3 structures were established using NMR spectrum and high-resolution ESIMS data. Compounds 1-5 were assayed to Plasmodium falciparum lactate dehydrogenase ( Pf LDH) for their antiplasmodial activity. Compounds 2 and 5 exhibited high activity with an IC 50 value of 0.74 and 0.79 µg/mL, respectively.