Near-Field Nanoscale Spectroscopy and Imaging of Enveloped Virus Particles and Layered Materials

Deeper understanding and technological progress in materials physics demand exploration of soft and hard matter at their relevant length scales. This research focuses on the nanometer length scale investigation of structural changes required for membrane fusion in virus nanoparticles and nano-spectroscopic investigation of layered material surfaces implementing scattering type scanning near-field optical microscopy (s-SNOM). Spectroscopy and imaging experiments were deployed to investigate the chemical and structural modifications of the viral protein and lipid bilayer under various environmental pH variations. It has been shown that breakage of viral membrane could occur even without the presence of a targeting membrane, if the environment pH is lowered. This is in contrary to the current viral fusion model, which requires virus binding to a host cell membrane for forming the fusion pore to release the viral genome. The fusion inhibitor compound 136 can effectively prevent the membrane breakage induced by low pH. The chemical surface stability and degradation of black phosphorus (BP) under ambient conditions have been studied using s-SNOM. We found that the degraded area and volume on the surface of black phosphorus increase with time slowly at the start of degradation and enlarge rapidly (roughly exponentially) afterward and reach saturation growth following S-shaped growth curve (sigmoid growth curve). The theoretical model presented suggests that the degraded sites in the adjacent surrounding causes the experimentally observed exponential growth of degraded area at the initial stage. By studying the BP surfaces coated by Al2O3, boron nitride (BN) and hybrid BN/Al2O3 layers through the period up to 6 months, it has been concluded that ~5 nm thin hybrid layer of BN/Al2O3 helps the surface passivation of BP flakes of thickness ~30 nm. This is supported by the electrical characterization results of BP field effect transistor coated with a BN/Al2O3 layer. We have performed infrared nano-spectroscopy on muscovite mica exfoliated on silicon and silicon dioxide substrates. We show that the near-field profile in s-SNOM can penetrate down to several hundreds of nanometers and enable spectroscopy of buried structures. We found spectral broadening of mica as its thickness increases revealing clearly the effect of size on the absorption response

Case Study: A Mobile ERP to Handle Multiple Sand Mining Sites (Welithota App)

Construction industry has been growing rapidly from 2002 due to massive constructions done for rehabilitation. Further post-tsunami construction also contributed to the exponential growth of the industry from 2004. Recent mega projects including Sothern, Central and Airport highways, lotus-tower, condominium housing projects, and tourist hotels are few examples which contributed directly to the growth in the economy. However, the construction industry directly depends on supply sand and other raw materials. Hence the mining industry governs productivity in the construction industry. The main concern when it comes to the mining industry is the environmental concerns due to excessive consumption of earthy resources. The natural resources are non-renewable and require thousands of years to recreate the extracted minerals. The sustainability within the mining industry attracts major concerns as ill-management in extraction jeopardizes the nature, industry and also the economy. The Sri Lankan government has imposed Laws and By-laws by act number 33 of 1992 and established Geological Survey and Mines Bureau (GSMB) to ensure that construction raw material extraction industry functions with sustainability without compromising nature. This case study has been conducted to acknowledge how the Information Communication Technology had incorporated within the industry stakeholder; raw material mining contractors for sustainable sand mining. Miners with valid licenses were integrated with mobile based technologies to manage the day-today operations and the systematic adherence to imposed Laws. Furthermore, the paper discusses how technology has improved governance and management in technologically unattained industry. This case study resulted in the mobile based Enterprise Resource Planning (ERP) mobile application ''Welithota'', titled to be the first mobile only ERP system in Sri Lanka which works standalone without an internet access or other technological infrastructure

Photodegradation and Thermal Effects in Violet Phosphorus

Violet phosphorus (VP) has garnered attention for its appealing physical properties and potential applications in optoelectronics. We present a comprehensive investigation of the photo degradation and thermal effects of exfoliated VP on SiO2 substrate. The degradation rate of VP was found to be strongly influenced by the excitation wavelength and light exposure duration. Light exposure to above bandgap light (> 532 nm) leads to significantly faster degradation, attributed to interactions with reactive oxygen species (ROS) generated by the laser. In contrast, lower energy excitation resulted in slower degradation due to reduced ROS generation. Analysis of photoluminescence (PL) spectra showed a gradual decline in the exciton population, signifying reduced lifetime and alterations in formation and stability, ultimately affecting VP's quantum efficiency. Power-dependent PL measurements at low temperature (4 K) showed that the intensities of neutral excitons and trions linearly increased with excitation power, while the energy difference between their peak energies decreased, indicating changes in the exciton energy gap due to degradation at higher laser power. At ambient temperature VP exhibited visible neutral exciton (X0) and trion (T) peaks with higher X0 spectral weight, indicating reduced thermal stability of T in VP crystals. Temperature dependent Raman showed the presence of VP up to 673K and back down to room temperature; however, peak intensities decreased and two new unknown peaks were observed indicating some level of thermal degradation. Our results provide deeper understanding of VP's degradation behavior and implications for optoelectronic applications.Comment: 22 pages, 6 figure

Application to Connect the Stock, Suppliers, and Deliverers via Inventory Management System

IPax is a 200-person IT firm situated in Sri Lanka. Due to the huge number of personnel, the decision was made to keep this inventory management system. Within the organization, employees require certain products for everyday usage. By generating orders through the system, employees may request from the warehouse manager the things they want. After an order has been created, the warehouse manager can see it as an order. If the requested item is in stock, the stock manager can accept and forward the request to the employee. There are several vendors that furnish the organization with the necessary products. When the warehouse manager changes the status of the order to "placed," the corresponding supplier is instantly notified and given the option to accept or reject the request. The warehouse manager is responsible for managing the available inventory and received inventory for each item that is purchased. This study can aid "IPax" in order to improve the company's manufacturing service level. Consideration of inventory simulation is advocated for the establishment of various supplier demand management scenarios

Control of Plasmonic Nanoantennas by Reversible Metal-insulator Transition

We demonstrate dynamic reversible switching of VO2 insulator-to-metal transition (IMT) locally on the scale of 15 nm or less and control of nanoantennas, observed for the first time in the near-field. Using polarization-selective near-field imaging techniques, we simultaneously monitor the IMT in VO2 and the change of plasmons on gold infrared nanoantennas. Structured nanodomains of the metallic VO2 locally and reversibly transform infrared plasmonic dipole nanoantennas to monopole nanoantennas. Fundamentally, the IMT in VO2 can be triggered on femtosecond timescale to allow ultrafast nanoscale control of optical phenomena. These unique features open up promising novel applications in active nanophotonics

Infrared Nanoimaging of Hydrogenated Perovskite Nickelate Synaptic Devices

Solid-state devices made from correlated oxides such as perovskite nickelates are promising for neuromorphic computing by mimicking biological synaptic function. However, comprehending dopant action at the nanoscale poses a formidable challenge to understanding the elementary mechanisms involved. Here, we perform operando infrared nanoimaging of hydrogen-doped correlated perovskite, neodymium nickel oxide (H-NdNiO3) devices and reveal how an applied field perturbs dopant distribution at the nanoscale. This perturbation leads to stripe phases of varying conductivity perpendicular to the applied field, which define the macroscale electrical characteristics of the devices. Hyperspectral nano-FTIR imaging in conjunction with density functional theory calculations unveil a real-space map of multiple vibrational states of H-NNO associated with OH stretching modes and their dependence on the dopant concentration. Moreover, the localization of excess charges induces an out-of-plane lattice expansion in NNO which was confirmed by in-situ - x-ray diffraction and creates a strain that acts as a barrier against further diffusion. Our results and the techniques presented here hold great potential to the rapidly growing field of memristors and neuromorphic devices wherein nanoscale ion motion is fundamentally responsible for function.Comment: 30 pages, 5 figures in the main text and 5 figures in the Supplementary Materia

Investigation of Crack Repairing Technique to Delay Fracture Initiation of Steel Members Subjected to Low Cycle Fatigue

Stress concentrations have become a common phenomenon in steel elements when arresting a fracture by implementing the crack stop hole (CSH) technique. Embedding the CSH with Carbon Fibre-Reinforced Polymer (CFRP) enhances the fatigue life by delaying fractures while achieving stiffness recovery due to the superior mechanical characteristics of the CFRP material. Hence, the low cyclic fatigue (LCF) behaviour of 90 strengthened and non-strengthened CSH specimens was examined in this context. These specimens were subjected to a range of 0 to 10,000 fatigue load cycles at a frequency of 5 Hz. At the end of fatigue exposure, the average tensile strength was measured in each case. The application of a CFRP patch on the CSH effectively recovered the strength losses while enhancing the strength in the range of 32% to 45% with respect to the non-strengthened specimens. The developed numerical model based on the cyclic J-integral technique agrees with the test results. This study introduced geometry-related design guidelines for this novel CSH hybrid technique

Noniridescent Biomimetic Photonic Microdomes by Inkjet Printing

Certain bird species have evolved spectacular colors that arise from organized nanostructures of melanin. Its high refractive index (similar to 1.8) and broadband absorptive properties enable vivid structural colors that are nonsusceptible to photo-bleaching. Mimicking natural melanin structural coloration could enable several important applications, in particular, for non-iridescent systems with colors that are independent of incidence angle. Here, we address this by forming melanin photonic crystal microdomes by inkjet printing. Owing to their curved nature, the microdomes exhibit noniridescent vivid structural coloration, tunable throughout the visible range via the size of the nanoparticles. Large-area arrays (&amp;gt;1 cm(2)) of high-quality photonic microdomes could be printed on both rigid and flexible substrates. Combined with scalable fabrication and the nontoxicity of melanin, the presented photonic microdomes with noniridescent structural coloration may find use in a variety of applications, including sensing, displays, and anticounterfeit holograms.Funding Agencies|Wenner-Gren Foundation; Swedish Research CouncilSwedish Research Council; Knut and Alice Wallenberg foundationKnut &amp; Alice Wallenberg Foundation; Swedish Foundation for Strategic researchSwedish Foundation for Strategic Research; Linkoping University; Wallenberg Wood Science Center the Wallenberg Wood Science Centre; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]</p