Sahu, Satyajit

For two hundred years, quaternions and octonions were explored, not a single effort was made on constructing the mathematical universe with more than eight imaginary worlds. We cross that 200 years old jinx and report dodecanion, a universe made of 12 imaginary worlds and show that once a fractal-like system is dynamic with 12 dimensions, it acquires a geometric feature unprecedented at lower dimensions. While the topology of octonion algebra remains an identity, the topology of a dodecanion algebra demands the coexistence of three distinct manifolds at a time and three distinct stereographic projections at a time. We define it as the condition for a self-operational mathematical universe. Earlier, dimensions were only a new dynamic associated with a new orthogonal axis, now, we assign modular or clock arithmetic systems in the singularity points of a system, thus, it assembles a mathematical structure where the systems are assembled one inside the other. The dimensions 12, 18, 20, 24, 30, 36 create a distinct catalog of manifolds. Since the maximum allowed higher dimension in recent physics is 10 (String theory) or 11 (M-theory), the dodecanion algebra with 12D is the simplest multinion that maps the topological variability and the interactions of physical worlds representing different dimensions, i.e., dynamics. We mapped here distinct projections from infinity during stereographic projections while transiting from 2 to 12 imaginary worlds. The dodecanion algebra has the ability to incorporate the manifolds created by multinions of higher dimensions, it is essential and sufficient for a generic self-operating universe.

Colloidal quantum dots (QDs) benefit from solution-phase processing and band-gap tuning for their application in solar cell development. Today's QD solar cells rely on solid-state ligand exchange (SLE) to replace bulky oleic acid (OA) ligands with small 1,2-ethanedithiol (EDT) ligands to develop a conducting hole transport layer (HTL). High volume contraction in EDT conjugated QD films, however, leads to crack and porosity in the HTL, which is a major cause of concern for the device reproducibility and large-area solar cell development. We show that partial removal of the OA ligands in the solution phase reduces the volume contraction in solid films, thereby allowing the growth of crack-free QD films in the SLE process. The cleaning of QDs by repeated precipitation and redispersion using a protic methanol (MeOH) solvent helps with partial removal of the OA ligands, but it is detrimental to the electronic properties of QDs. We develop a one-step solution-phase partial ligand-exchange process using ammonium salts, which enable partial replacement of the OA ligands and passivation of the QD surface. Introduction of the facile partial ligand-exchange process eliminates the need for tedious and wasteful multiple cleaning steps with MeOH, while improving the photophysical properties of QDs. The advancement in QD processing helps to build crack-free, smooth, and conjugated QD films for their deployment as HTLs in solar cell development. Partial ligand exchange with NH4SCN leads to a 1.5 times increase in p doping and mobility over multiple MeOH-cleaned PbS QD films. HTLs developed using NH4SCN QDs show an improved photovoltaic performance to attain a 10.5% power conversion efficiency. Improvement in the depletion width and hole collection efficiency leads to a superior photovoltaic performance, as confirmed from experimental studies and one-dimensional solar cell capacitance simulation.

Quantum capacitance and quantum inductance, two well-known signatures of quantum properties detect here subtle changes in the resonance frequencies as instant quantum markers of cancerous mutation of proteins. We find that any quantum property that is destroyed by measurement is true only if singular wave function is measured. Here, as we image the three magnetic wave functions of a protein complex, in three layers of Schrödinger’s wave functions packed one inside another, we find their geometric phase (Zak phase) rebuilds each other from nano-to-micro scale. Using the difference signal between magnetic and thermal nano-sensors located closely at the atomic edge of a probe, our interference-based sensing mapped cancerous microtubule’s local structural changes at the very onset of cancer in the noisy environments.

Over the past few years, two-dimensional transition metal dichalcogenides (2D-TMDC) have attracted huge attention due to their high mobility, high absorbance, and high performance in generating excitons (electron and hole pairs). Especially, 2D molybdenum disulfide (MoS2) has been extensively used in optoelectronic and photovoltaic applications. Due to the low photo-to-dark current ratio (Iphoto/dark) and low speed, pristine MoS2-based devices are unsuitable for these applications. So, they need some improvements, i.e., by adding layers or decorating with materials of complementary majority charges. In this work, we decorated pristine MoS2 with reduced graphene oxide (rGO) and got improved dark current, Iphoto/dark, and response time. When we compared the performance of pristine MoS2 based device and rGO decorated MoS2 based device, the rGO/MoS2-based device showed an improved performance of responsivity of 3.36 A W−1, along with an Iphoto/dark of about 154. The heterojunction device exhibited a detectivity of 4.75 × 1012 Jones, along with a very low response time of 0.184 ms. The stability is also outstanding having the same device performance even after six months.

Chalcogenide-based quantum dots are useful for the application of memory-switching devices because of the control in the trap states in the materials. The control in the trap states can be achieved using a hot-injection colloidal synthesis method that produces temperature-dependent size-variable quantum dots. In addition to this, formation of a nanoscale heterostructure with an insulating material adds to the charge-trapped switching mechanism. Here, we have shown that the colloidal monodispersed CdSe quantum dots and poly(4-vinylpyridine) (PVP) formed a nanoscale heterostructure between themselves when taken in a suitable ratio to fabricate a device. This heterostructure helps realize memory-switching in the device with a maximum on-off current ratio of 105. The switching in the device is mainly due to the trap states in the CdSe quantum dots. The conduction in the off state is due to thermal charge injection and space charge injection conduction and in the on state, due to the Ohmic conduction mechanism.

We have fabricated an organic non-volatile memory device wherein the ON/OFF current ratio has been controlled by varying the concentration of a small organic molecule, 2,3-Dichloro-5,6-dicyano-p-benzoquinone (DDQ), in an insulating matrix of a polymer Poly(4-vinylphenol) (PVP). A maximum ON-OFF ratio of 106 is obtained when the concentration of DDQ is half or 10 wt. % of PVP. In this process, the switching direction for the devices has also been altered, indicating the disparity in conduction mechanism. Conduction due to metal filament formation through the active material and the voltage dependent conformational change of the organic molecule seem to be the motivation behind the gradual change in the switching direction.

The data storage requirement in the digital world is increasing day by day with the advancement of the internet of things. In this respect, nonvolatile resistive random-access memory is an option that provides high density and low power data storage capabilities. In this work, zero-dimensional colloidal CdS quantum dots and a polymer composite at an appropriate ratio were used to fabricate a memristive device. Comparison with a pristine CdS quantum dot-based device reveals that a surrounding matrix around the quantum dots is needed for observing memristive behavior. The quantum dots embedded in the polymer matrix device showed extremely stable electrical switching behavior that can be operated for more than 300 cycles and 60 000 seconds. Moreover, the device needs extremely low power to operate at a very high speed. The smooth surface morphology dictates a charge trapping mechanism for the switching phenomenon; however, an interplay between different charge transport mechanisms leads to the fast switching and high on-off ratio of the device.

A new dodecanuclear organostannoxane with an unprecedented structure comprising four O-capped clusters is isolated using 2-(phenylazo)phenyl substitution on the tin center. The formation of [(RSn)12(µ3-O)4(µ2-O)3(µ2-OH)21] [Cl]·5PhCH3·THF (1) is achieved by the complete hydrolysis of RSnCl3 [R = 2-(phenylazo)phenyl] in the presence of excess sodium hydroxide in refluxing ethanol/water (1:1) mixture. Complex 1 crystallizes in the triclinic space group P-1. The absence of N→Sn intramolecular coordination in the molecular structure of 1 illustrates the hemi-labile nature of N→Sn intramolecular coordination. Each tin atom in complex 1 is hexacoordinated, possessing distorted octahedral geometry. All the 12 Sn centers in complex 1 are held together through four µ3-O2− three µ2-O2−, and twenty-one µ2-OH− ligands resulting in the formation of a central Sn12 oxo-hydroxo core having four o-capped clusters in the framework. I-V characteristic curve of complex 1 based device displayed an interesting negative differential resistance (NDR) behavior in the voltage range of 1.0–1.8 V with excellent repeatability of 200 cycles.

Write once read many times (WORM) memory devices based on the resistive switching mechanism of a sputtered amorphous BaTiO3 (am-BTO) thin film in a metal-insulator-metal structure is fabricated on a FTO coated glass substrate with a silver top contact. Fabricated devices show the switching from a low-conductance state to a high-conductance state with the formation of conductive filament(s) in the am-BTO layer. The memory characteristics are investigated as a function of thickness of am-BTO layer, which is determined by varying the deposition time. Devices with all deposited thicknesses show data retention for more than 4000 s and 300 reading cycle. Devices with 180 nm thickness show a high on-off ratio on the order of 106. The fabricated WORM devices exhibit good reading-endurance and data-retention characteristics.

A substantial ion flow in a normally wet protein masks any other forms of signal transmission. We use hysteresis and linear conduction (both are artifacts) as a marker to precisely wet a protein, which restricts the ionic conduction (hysteresis disappears), and at the same time, it is not denatured (quantized conductance and Raman spectra are intact). Pure electric visualization of proteins at work by eliminating the screening of ions, electrons, would change the way we study biology. Here we discuss the technical challenges resolved for imaging a protein or live cell using nonlinear dielectric response (spatial distribution of conductance, capacitance and phase, GCP trio). We electromagnetically triggered electrical, mechanical, thermal and ionic resonant vibrations in a protein. During resonant oscillations, we imaged the protein using resonant scanning tunneling microscopy of biomaterials (Brestum) and during ionic firing we imaged live what happens inside an axon core of a neuron by using our atomic scale scanning dielectric microscopy (Asadim). Both Asadim and Brestum are housed in a homebuilt scanning tunneling microscope (bio-STM) and a special micro-grid developed by us (patent JP-5187804) for fractal supercomputing. We found the trick to turn a membrane transparent and see inside without making any physical contact. We image live that a protein molecule adopts a unique configuration for each resonance frequency, - thus far unknown to biology. "Membrane alone fires" is found to be wrong after a century, micro-neuro-filaments communicate prior to firing to decide its necessity and then regulate it suitably. We introduce a series of technologies e.g., fractal grid, point contact, micro THz antenna, to discover that from atomic structure to a living cell, the biomaterials vibrate collectively.