No abstract

BaCe0.54Zr0.36Y0.1O2.95 (BCZY10) ceramic powder was synthesized by a modified sol-gel method using metal nitrate salt as pre-cursors. The sample was prepared using three different types of surfactants namely polyethylene glycol (PEG) 6000, sodium dodecyl sulphate (SDS) and cetyltrimetylammonium bromide (CTAB). Thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectrometry was used to analyze the thermal decomposition of the dried (T=325 °C) and calcined (T=1100 °C) powder. Standard sample prepared without surfactant is denoted as A1 while the sample that prepared using PEG, SDS and CTAB as surfactant was denoted as A2, A3, and A4 respectively. TGA results indicate that all the samples were almost completely decomposed at ~800 °C except for A2. It showed the lowest thermal decomposition temperature Ttd=739 °C. The highest total weight loss ~94.7% is shown by sample A4 than others. The sample with the presence of surfactant exhibits faster reaction rate for the first decomposition stage which is t = 8 min, 11 min, and 13 min for sample A2, A3, and A4 respectively compared to A1 (t = 18 min). The A2 sample shows faster reaction rate indicates that BCZY10 compound might be formed earlier faster due to the long carbon chain posses by PEG surfactant. The higher number of carbon chain present in the surfactant may accelerate the combustion process and the formation of metal oxide compounds. FTIR spectra illustrated that the carbonate residue still remained in all the samples even after calcined at 1100 oC. This result indicates that the used of surfactant does not give a significant effect on preventing the formation of BaCO3. However, the intensity of metal-oxygen band at ~450 cm-1 become stronger indicates that the formation of BCZY10 compound was being enhanced.

This study focuses on works related to urease inhibitors published from 1970 to 2021, gathered from the Web of Science database. This paper aims to examine the trends of research involving urease inhibitors, as there have been no centralised study that utilises bibliometric methods on the related research fields, methods used, as well as collaborations. The total number of publications examined in this paper after filtering is 574 and the number of review articles on urease inhibitors is on the low side considering other research topics published within the 51-year period. Experimental works are still the core method of gathering information on the usefulness of urease inhibitors in all fields within the investigated time span. From the mid-2000s, theoretical investigations emerged as a complement to experimental research, mostly in the form of molecular docking studies. As in the other fields of study, theoretical works have been accepted as part of research methods to examine the molecular interactions between compounds and urease. The main partners to consider for cooperation in this field of study are those in Pakistan, China, the United States, New Zealand and Spain as their institutions house researchers that are outstanding in the field and they produce articles that are highly cited.

In this study, the structural and electronic properties of the N-(n-Butyl) Thiophosphoric Triamide (NBPT) inhibitor, in the form of monoamidothiophosphoric acid (MATP), as attached to urease enzyme, has been investigated. These include the electron density, molecular orbitals involved in the interactions, and the whole system’s charge distributions. The difference between the interaction of urease-NBPT and urease-urea was conducted throughout this study. This comparison was crucial to prove the NBPT inhibitor’s mechanism to slow down urea’s hydrolysis in the soil solution. The quantum mechanical calculations were performed at the level theory B3LYP/6-31G(d,p). The urease-NBPT complex has higher interaction energy than the urease-urea complex, in which the interaction energy is –1.6787 eV. The urease-NBPT complex has a lower molecular electronic energy gap than the urease-urea complex, at 0.9527 eV. The graphical representation of HOMO, LUMO, and electrostatic potential maps indicates that the NBPT inhibitor can create favourable interaction with the atoms at urease’s active site.

BaCe0.54Zr0.36Y0.1O2.95 (denoted as BCZY10) ceramic powder was synthesized by a modified sol-gel method using metal nitrate salts as precursors. The samples were prepared using two different types of surfactants which are cationic surfactant of hexadecyldimethylammonium bromide (HTAB), nonionic surfactant of polyoxyethylene (10) oleyl ether (Brij 97), and sample without surfactant as a control. All samples were labeled as S1, S2, and S3 respectively. They were dried and calcined at T=325 °C and T=1100 °C accordingly. Chemicals bonding of the compound were analyzed using Fourier transform infrared (FTIR) spectrometry and their phase formation was identified by X-Ray Diffractometer (XRD). All the dried samples showed the adsorption peak at 3200-3700 cm-1 that related to the overlapping of OH stretching originated from –OH terminal group and N-H stretching vibrations. The peaks appeared at 1620-1640 cm-1 can be assigned to C=O stretching and at 1380-1450 cm-1 can be attributed for N-H bending vibration. The adsorption peak ≈500 cm-1 of metal-oxygen bond for all the calcined samples became pronounces indicating that the metal complexes were transformed to metal oxides. XRD results confirmed that S2 and S3 formed a single-phase of Ba (Ce,Zr)O3 perovskite type-oxide and S1 consists of multi-phases compound which are dominated by BaCeO3, and BaZrO3. Therefore, the used of different type of surfactant was found to give a significant effect on the synthesizing single-phase of BCZY10 ceramics compound.