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This paper presents the effects of various nanosilica (NS) contents on the mechanical properties of polyvinyl alcohol (PVA) fiber-reinforced geopolymer composites (PVA-FRGC). Microstructure analysis with X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to characterize the geopolymer composites. The results showed that the mechanical properties in terms of compressive strength, impact strength, and flexural behavior were improved due to the addition of NS to the PVA-FRGC. The optimum NS content was 1.0 to 2.0 wt%, which exhibited highest improvement in the above mechanical properties. Microstructure analysis showed that the addition of NS up to an optimum level densified the microstructure of the matrix as well as the PVA fiber–geopolymer matrix interface.

The emergence of diverse peptide derivatives has been due to constant efforts to find a specific peptide with pronounced biological activity for effective application as a therapeutic. Spinorphin-peptide products have been reported to possess various applications and properties. In the present study, spinorphin peptides with a rhodamine residue and a modification in the amino acid backbone were synthesized by a solid-phase method using Fmoc chemistry. The results obtained from the spectral and electrochemical techniques used: Scanning electron microscopy (SEM), UV-vis, fluorescence, infrared spectroscopy (IR), and voltammetry were used to elucidate the structural characteristics and some physicochemical properties to gain insight into their behavior in the solid state and in aqueous solutions with different pHs. Both Rh-S5 and Rh-S6 had compound anticonvulsant effect comparable to Rh-S against psychomotor seizures at the highest dose of 20 μg. Furthermore, Rh-S6 showed a strong ability to inhibit seizure propagation and had a similar threshold to Rh-S against the intravenous pentylenetetrazol induced clonic seizure in mice; one of the three hybrid spinorphin analogs tested when screened for anticonvulsant activity. Biological tests against several bacterial pathogens such as Staphylococcus aureus, Escherichia coli, and Bacillus cereus showed similar results to negative control of the new peptide derivatives. The compounds also showed weak activity against Candida albicans fungus. The antioxidant testing results revealed more than 50% activity by reviewing the radical deterrence capabilities of 2,2-diphenyl-1-picrylhydrazyl (DPPH). The results are indicative of the ongoing search for universal antimicrobial agents with pronounced synergism when used simultaneously as anticonvulsant, antibacterial, and antifungal agents.

The goal of this research is to synthesize and characterize Fe3O4@Chitosan-AgNP nanocomposites in order to determine their antibacterial activity. The research methods include the synthesis of Fe3O4@Chitosan-AgNP nanocomposites, as well as the characterization of nanoparticles using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) analysis, and subsequent antibacterial activity tests. The study’s findings demonstrated the successful synthesis of Fe3O4@Chitosan-AgNP nanocomposites, followed by nanoparticle characterization using SEM, TEM, XRD, and FTIR. Based on the XRD results, the conjugation of Fe3O4@Chitosan-AgNP nanocomposites has been successfully formed, as evidenced by the appearance of characteristic peaks of Fe3O4, chitosan, and AgNPs. According to the FTIR results, the interaction between chitosan-AgNPs and conjugated Fe3O4 occurred via the N atom in the NH2 group and the O atom in the OH group, and C=O. The SEM and TEM images also show that the Fe3O4@Chitosan-AgNP conjugation is a nanoparticle-based composite material. The combination of nanocomposites Fe3O4@Chitosan-AgNPs has antibacterial activity, inhibiting the growth of bacteria such as Bacillus cereus and Escherichia coli.

Telah dilakukan penelitian tentang geopolimer berbasis fly ash dengan penambahan abu sekam padi. Penelitian ini bertujuan untuk mengetahui struktur dan sifat mekanik geopolimer berbasis fly ash dengan penambahan abu sekam padi. Geopolimer berbasis fly ash dibuat dengan penambahan abu sekam padi 0%, 20% dan 40% menggunakan metode aktivasi alkali dan dipanaskan pada suhu 70℃ selama 2 jam. Struktur mikro dari sampel  diketahui dengan menggunakan teknik X-Ray Diffraction (XRD) dan menggunakan Scanning Electron Microscopy (SEM). Gugus fungsi dari sampel diperoleh berdasarkan pengujian Fourier Transform Infra Red (FTIR). Sifat mekanik seperti Kuat tekan dari sampel diuji menggunakan Testing Mechine. Massa jenis, porositas dan kuat lentur dilakukan pengukuran terhadap sampel. Hasil penelitian menunjukkan diperoleh fase trydimate yang tertinggi pada sampel Geo FA+ASP (60+40)%. Hasil karakterisasi Scanning Elektron Microscopy (SEM) menunjukkan material penyusun sampel telah berikatan dengan baik walaupun sebagian kecil pertikel fly ash dan abu sekam padi masih terlihat dengan jelas. Gugus fungsi pembentuk geopolimer diperoleh pada stretching Si-O-Si dengan nilai gelombang antara 478-461cm-1 dan 791-781cm-1. Massa jenis tertinggi diperoleh pada sampel dengan penambahan 40% abu sekam padi dan porositas tertinggi diperoleh pada sampel tanpa penambahan abu sekam padi. Kuat tekan yang terbesar diperoleh dari sampel geopolimer berbasis fly ash tanpa penambahan abu sekam padi sedangkan kuat lentur tertingi diperoleh dari sampel geopolimer berbasis fly ash dengan  penambahan abu sekam padi sebesar 40%.