A gold-coated Kretschmann setup has been constructed and explored as a surface plasmon resonance (SPR) platform, specifically tailored for the detection of low-concentration sodium chloride (NaCl) solutions. The setup employs a BK7 prism coated with a 50 nm gold layer, serving as a plasmonic layer, to induce resonance. This resonance arises from the interplay between light waves and free electrons propagating at the interface of two media. The experimental findings reveal a notable resonance angle shift of 10° when the NaCl concentration is varied from 0 to 2.5 %. Furthermore, angle interrogation provides insightful details about the sensor's response to changes in the refractive index, showcasing a commendable sensitivity of 2400°/RIU, a high level of linearity at 0.9771, and an impressive resolution of 0.217 %. The demonstrated capabilities of this sensor underscore its potential for widespread applications, particularly in the monitoring of salt concentration across diverse domains such as seawater analysis, food processing, and fermentation processes. The robust performance and precision of this proposed sensor position it as a valuable tool with promising prospects for addressing the needs of various industries dependent on accurate salt concentration measurements.
Communities in Indonesia were resistant to lockdown policies, Large-Scale Social Restrictions (PSBB) and the Enactment of Restrictions on Community Activities (PPKM). Both policies were implemented numerous times in the country during the COVID-19 pandemic, and these caused widespread unrest. Language with the terms PSBB and PPKM, which several times extended suddenly, not informed to the community, inconsistent in its implementation, makes the community feel mad, neglected the needs of their life, and severe rejections. This research was conducted with a qualitative approach sourced from primary and secondary data. Primary data were obtained from electronic media news that shows public resistance and government policies published through the official government web. Meanwhile, secondary data were obtained from journal articles discussing community resistance related to policies to prevent the spread of the COVID-19 pandemic. The results showed that various terms translated from the term lockdown to the time PSBB and PPKM had consequences for policy misalignment with community expectations. The switching of language from lockdown to PSBB and PPKM has caused resistance in the community because it has allowed the government to be economically irresponsible. Therefore, the government needs to inform and be responsible, so that policies can run effectively.