One-pot synthesis of versatile sphere-like nano adsorbent MnAl2O4 (MAO): an optical and magnetic material for efficient fluoride removal and latent finger print detection.

Spherically shaped trimetallic MnAl2O4 (MAO) nanoadsorbent was prepared in an one-pot synthesis process for the removal of excess fluoride from water. The adsorbent was characterized by thermogravimetric analysis (TGA), X-ray diffraction study (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), etc. The adsorption property for fluoride on the MAO was analyzed by batch experiments varying the adsorbent dose, pH, contact time, and initial fluoride concentration. The results showed that the fluoride uptake behavior of the samples could precisely be fitted by the Freundlich model, and the maximum adsorption capacity was estimated to be 39.21 mg/g at room temperature. The pseudo-second-order models accurately described the adsorption kinetics data. The regenerated sample showed excellent reusability along with high removal capacity on real water sample also. The underlying fluoride adsorption mechanism via ion-exchange and electrostatic interaction was established from X-ray photoelectron spectroscopy (XPS) and zeta potential studies. The sample showed excellent luminescence with blue emission with a band gap of 2.6 eV. The materials also showed good elastic behavior exhibiting the Poisson's ratio (σ) 0.32 and excellent latent figure print detection capacity distinguishing the clearly the ridge and furrow regions under UV light. The magnetic behavior was also found to be in long range with antiferromagnetic characteristics.

Surface Potential Tuned Single Active Material Comprised Triboelectric Nanogenerator for a High Performance Voice Recognition Sensor.

To fabricate a high-performance and ultrasensitive triboelectric nanogenerator (TENG), choice of a combination of different materials of triboelectric series is one of the prime challenging tasks. An effective way to fabricate a TENG with a single material (abbreviated as S-TENG) is proposed, comprising electrospun nylon nanofibers. The surface potential of the nanofibers are tuned by changing the voltage polarity in the electrospinning setup, employed between the needle and collector. The difference in surface potential leads to a different work function that is the key to design S-TENG with a single material only. Further, S-TENG is demonstrated as an ultrahigh sensitive acoustic sensor with mechanoacoustic sensitivity of ≈27 500 mV Pa-1 . Due to high sensitivity in the low-to-middle decibel (60-70 dB) sounds, S-TENG is highly capable in recognizing different voice signals depending on the condition of the vocal cord. This effective voice recognition ability indicates that it has high potential to open an alternative pathway for medical professionals to detect several diseases such as neurological voice disorder, muscle tension dysphonia, vocal cord paralysis, and speech delay/disorder related to laryngeal complications.

Design of a self-powered triboelectric face mask.

Usage of a face mask has become mandatory in many countries after the outbreak of SARS-CoV-2, and its usefulness in combating the pandemic is a proven fact. There have been many advancements in the design of a face mask and the present treatise describes a face mask in which a simple triboelectric nanogenerator (TENG) with an electrocution layer may serve the purpose of filtration and deactivation of SARS-CoV-2. The proposed mask is designed with multilayer filters, in which the inner three layers act as a triboelectric (TE) filter and the outer one as an electrocution layer (EL). The viral particles experience a mildshock in EL due to the electric field produced between the electrocution layers by contact electrification. Four pairs of triboelectric series fabrics, i.e. polyvinylchloride (PVC)-nylon, polypropylene (PP)-polyurethane (PU), latex rubber-PU, polyimide (PI)-nylon are studied to establish the efficacy of the mask. The motional force exerted on triboelectric filter materials can produce sufficient electric power to activate EL. The proposed mask can be used by a wide range of people because of its triboelectric self-powering (harvesting mechanical energy from daily activities, e.g. breathing, talking or other facial movements) functionalities to ensure effective filtration efficiency. More importantly, it is expected to be potentially beneficial to slow down the devastating impact of COVID-19.

Multi-wave-mixing-induced nonlinear modulation of diffraction peaks in an opto-atomic grating.

We propose an atomic model in close-loop configuration, which exhibits controllable symmetric and asymmetric evolution of significantly enhanced diffraction peaks of the weak probe beam in an opto-atomic grating at far-field regime. Such results are obtained by the linear and nonlinear modulation of the intensities of the diffraction peaks as a result of multi-wave-mixing-induced modification of spatially modulated coherence in a closed four-level atomic system. Novelty of the results lies in predicting the diffraction pattern with uniform peak height due to the dominance of the amplitude part of the grating-transfer-function at the condition of exact atom-field resonance, which is unique to the present model. Efficacy of the present scheme is to apply it in producing nonlinear light generated by four-wave-mixing-induced control of spatially modulated coherence effect. The work also finds its importance for its applicability in the field of all-optical devices.

Optical absorption microscopy of localized atoms at microwave domain: two-dimensional localization based on the projection of three-dimensional localization.

A new approach for achieving two - dimensional (2D) atom localization microscopy based on the projection of three - dimensional (3D) localization in the plane of the detector is described in the present work. Spatial variation of the position-dependent 2D-localization pattern in the xy-plane is obtained with the shifting of the position of the detector along the z-axis under the parallel- and cross- axis configurations of the standing-wave fields. An attempt is made to study the 2D-localization characteristics in the specific parametric conditions for which the localization structures evolve with different shapes eventually leading to 100% detection probability of the atom both in the sub-wavelength and sub-half-wavelength regimes. The scope of tuning the cross-axis configuration over a wide range adds novelty and robustness to this model. Apart from the 2D-localization, various localization patterns with eight- to single-peak structures appear as interesting outcomes through the efficient manipulation of control parameters in the study of one-dimensional (1D) atom localization. The application of the traveling-wave field or its equivalent appears to be unique in achieving high-precision localization with maximal probability (100%) in both the 1D and 2D field-configuration schemes. Proper tuning of the traveling wave accompanied by the standing wave in the 1D scheme results in the single-peak localization in the sub-half-wavelength range. As a whole, the present work seems to be very much efficient for high-precision optical lithography.