Multiband terahertz metamaterial perfect absorber for microorganisms detection.

We report a multi-resonant terahertz (THz) metamaterial perfect absorber (MPA)-based biosensor in the working frequency range of [Formula: see text] for sensing of microorganisms (such as fungi, yeast) and wheat pesticides. Nearly [Formula: see text] absorption is realized at [Formula: see text] and [Formula: see text]. We designed our THz MPA sensor making resonators' gap area compatible with the microorganisms' size. To obtain optimum performance of the MPA, a mapping of amplitudes and shifts in the absorption resonance peaks with different structural parameters of the resonators is carried out. A very high-frequency shift is obtained for microorganisms such as Penicillium chrysogenum (fungi), yeast, and pesticides (Imidacloprid, N, N-Diethyldithiocarbamate sodium salt trihydrate, Daminozide, N, N-Diethyldithiocarbamate sodium salt hydrate, and Dicofol). An equivalent circuit model using Advance Design System (ADS) software is developed. The calculated results through the model show similar trends as obtained in the simulations using CST. Investigations of the effect of incidence angle of THz wave on the absorption spectra of the MPA are also carried out. It is found that incidence angle does not impact the stability of the lower resonance absorption peak (1.79THz). Due to the wide working frequency range, the proposed sensor is extremely suitable for the detection of all range of pesticides because their specific absorption fingerprint lies in the frequency range of 0-3.8THz. We believe that our sensor could be a potential detection tool for detecting pesticide residues in agriculture and food products. The THz MPA-based biosensor is capable of detecting a very small change in the effective dielectric constant of the MPA environment. Therefore, it can also offer huge opportunities in label-free biosensing for future biomedical applications.

A New ICU Delirium Prevention Bundle to Reduce the Incidence of Delirium: A Randomized Parallel Group Trial.

INTRODUCTION: Although various preventive strategies have been advocated, delirium is common in critically ill patients and is associated with increased morbidity, mortality, and long-term adverse effects. The efficacy of a novel delirium prevention bundle in mechanically ventilated critically ill patients was investigated in this study. METHODS: In this randomized controlled trial, 50 mechanically ventilated adult patients in a tertiary care medical-surgical intensive care unit (ICU) were randomized to receive either delirium prevention bundle protocol or standard of care protocol. Delirium was assessed daily using the Confusion Assessment Method for the ICU (CAM-ICU) score by an independent investigator up to 28 days or death or discharge. The primary outcome was the incidence of new-onset delirium. Secondary outcomes were duration of mechanical ventilation, ICU length of stay (ICU-LOS), hospital LOS, and other adverse events. RESULTS: There was a 20% reduction in the incidence of delirium in the intervention group (36 vs 56%; p = 0.156). The 28-day mortality (28 vs 24%; p = 0.747), duration of mechanical ventilation (9 vs 12 days; p = 0.281), ICU-LOS (11 vs 12 days; p = 0.221), and hospital LOS (16 vs 20 days; p = 0.062) were similar between the groups. CONCLUSION: Implementation of delirium prevention bundle does not reduce the incidence of delirium compared to standard of care protocol in mechanically ventilated critically ill patients. HOW TO CITE THIS ARTICLE: Malik AK, Baidya DK, Anand RK, Subramaniam R. A New ICU Delirium Prevention Bundle to Reduce the Incidence of Delirium: A Randomized Parallel Group Trial. Indian J Crit Care Med 2021;25(7):754-760.

Terahertz radiation generation by beating of two spatial-Gaussian lasers in the presence of a static magnetic field.

Resonant excitation of terahertz (THz) radiation based on beating of two spatial-Gaussian lasers having different frequencies and wave numbers but the same electric field amplitudes is proposed in a spatially periodic density plasma in the presence of a static magnetic field applied perpendicular to the direction of propagation of the lasers. In this process, the ponderomotive force is developed with its components parallel and perpendicular to the direction of propagation of the lasers. This leads to a nonlinear oscillatory current that resonantly excites the THz radiation with the frequency of the order of the upper hybrid frequency. The contribution of magnetic field, laser beamwidth, and amplitude and periodicity of the density ripples is discussed for the efficient THz radiation generation. With the optimization of these parameters, the efficiency on the order of 10(-3) or larger can be achieved in the present scheme.