Optimizing optoelectronic performance: impact of polar-terminated zinc oxide on MoS2Van der Waals heterostructure.

We report a study on the stability, optical absorption and modulated electronic properties of the ZnO(0001-) and MoS2Van der Waals heterostructure using density functional theory. We employed a supercell of ZnO/MoS2hybrid and specifically explored the effects of creating an interface with the O-terminated face of ZnO while considering the interlayer interaction. We observed an increase in the band gap opening of MoS2within the hybrid structure (1.37 eV) is primarily attributed to in-plane strain, with minimal contribution from the identified charge transfer occurring from MoS2to ZnO. Notably, the hybrid structure exhibits enhanced photo absorption in the visible and near-infrared regions, highlighting their significance for optoelectronic applications.

Longitudinal traffic conflict analysis of autonomous and traditional vehicle platoons in field tests via surrogate safety measures.

Autonomous vehicles (AVs) have been introduced into the traffic stream alongside traditional vehicles (TVs) with the expectation of improved transportation safety, efficiency, and reliability. The majority of AV safety research has been done through simulation. The results of such research on the safety performances of AVs are heavily influenced by the methodological framework, algorithms, and assumptions about AV driving characteristics in a simulated environment. There is a need for AV safety research based on real-world settings before any wide-scale deployment of this technology. This paper investigates the impact of the presence of SAE level 2 AVs in the traffic stream in reducing longitudinal traffic conflicts using Surrogate Safety Measures on a real-world open-source database of mixed traffic trajectories. The analysis is conducted for both AV-exclusive and mixed AV-TV platoons. Furthermore, we explore whether the presence of AVs decreases longitudinal traffic conflicts in two-vehicle platoons comprising AV and TV mixed leaders and followers. We find that an exclusive AV platoon behaves similarly to an exclusive TV platoon and produces similar longitudinal conflicts. However, mixed platoons with both AVs and TVs result in a higher number of longitudinal conflicts. Maintaining near-identical leader-follower conditions, we find that the number of conflicts in mixed platoons when an AV follows a TV is higher than when a TV follows an AV. The increase in conflict numbers in a TV-AV mixed platoon can be attributed to AV's longer response time lag. In summary, analyses conducted in this paper indicate that exclusive platoons and pairs of vehicles exhibit fewer longitudinal conflicts than mixed platoons and pairs.

The chimera of S1 and N proteins of SARS-CoV-2: can it be a potential vaccine candidate for COVID-19?

INTRODUCTION: Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emerged as one of the biggest global health issues. Spike protein (S) and nucleoprotein (N), the major immunogenic components of SARS-CoV-2, have been shown to be involved in the attachment and replication of the virus inside the host cell. AREAS COVERED: Several investigations have shown that the SARS-CoV-2 nucleoprotein can elicit a cell-mediated immune response capable of regulating viral replication and lowering viral burden. However, the development of an effective vaccine that can stop the transmission of SARS-CoV-2 remains a matter of concern. Literature was retrieved using the keywords COVID-19 vaccine, role of nucleoprotein as vaccine candidate, spike protein, nucleoprotein immune responses against SARS-CoV-2, and chimera vaccine in PubMed, Google Scholar, and Google. EXPERT OPINION: We have focussed on the use of chimera protein, consisting of N and S-1 protein components of SARS-CoV-2, as a potential vaccine candidate. This may act as a polyvalent mixed recombinant protein vaccine to elicit a strong T and B cell immune response, which will be capable of neutralizing the wild and mutated variants of SARS-CoV-2, and also restricting its attachment, replication, and budding in the host cell.

Development of a smartphone-based real time cost-effective VOC sensor.

Air pollution by various volatile organic compounds (VOC) is a matter of concern for us. So in this regard, designing real-time VOC responsive materials is gaining attention across the scientific community. In this present work, we have developed an inexpensive VOC sensor based on a Meisenheimer complex derived from picric acid and N,N'-dicyclohexylcarbodiimide. The sensor coated TLC plate was used as a sensor of potentially harmful VOCs. The sensor coated TLC plate looks deep red colored and does not show any fluorescence emission under 366 nm UV light. But in the presence of harmful volatile organic compounds like benzene, toluene, xylene, etc the sensor coated TLC plate becomes orange colored and it also shows strong yellow emission under 366 nm UV light. This property was utilized to detect the VOCs by fluorescence spectroscopy. The detection limit for various VOCs was found to be in the range of 0.7-9 ppm. To make the sensor user friendly, we have demonstrated a method where VOCs can be detected using a smartphone in real-time and also the setup is portable.

Distinguishing strain, charge and molecular orbital induced effects on the electronic structure: graphene/ammonia system.

Molecular adsorption at the surface of a two-dimensional material poses numerous questions regarding the modification to the band structure and interfacial states, which of course deserve full attention. In line with this, first principles density functional theory is employed on a graphene/ammonia system. We identify the effects on the band structure due to strain, charge transfer and presence of molecular orbitals (MOs) of NH3 for six adsorption configurations. Induced-strain upon ammonia-adsorption opens the band gap (E g) of graphene due to the breaking of translational symmetry. The charge transfer/MOs of NH3 shifts the equilibrium Fermi energy (E F). The E g and E F values and charge density distribution are dependent on the adsorption configuration, where the MO structure of NH3 plays a crucial role. The presence of MOs of N or H-originated pushes the unoccupied states of graphene towards E F. NH3 forms an interfacial occupied state originating from N2p below the E F within ∼1.6 to 2.2 eV for all configurations. These findings enhance fundamental understanding of graphene/NH3 system.

Exploring the heterogeneity in the cyclone evacuation decision in the context of developing economy: A case study of costal Bangladesh.

The critical role of evacuation, particularly for the communities in developing countries exposed to cyclones, has only been realized after some disastrous evacuation experiences in recent cyclones. A profound understanding of the factors influencing the evacuation behavior is necessary to reduce the loss of lives, especially in the cyclone prone communities. The purpose of this research is to identify the key factors influencing households' evacuation decision during a cyclone in developing economies. To this end, the research employs state of the art discrete choice modeling techniques referred to as mixed logit models. The study builds on the data collected in 1991 from the coastal areas of Bangladesh following the cyclone Sidr. The analysis result reveals that the evacuees of developing countries like Bangladesh resort to nearby tall buildings during cyclone due to the insufficient facilities provided by the cyclone centers. In case of mandatory evacuation and for temporary house owner, the households' decision to evacuate is found to be uniform. However, significant heterogeneity is found in the households' decision to evacuate whenever they receive a voluntary notice and also if they live sufficiently far from the sea shore. The factors that are identified to be influencing households' evacuation decision during a cyclone will enable potential evacuees to better evaluate their decision and consequently make more informed decision about the timing as well as the necessity of evacuation. The analysis result will also help emergency managers to decide on the timing and the type of evacuation orders they need to provide for reducing causalities due to landfall caused by cyclones.

α,ε-Hybrid Peptide Foldamers: Self-Assembly of Peptide with Trans Carbon-Carbon Double Bonds in the Backbone and Its Saturated Analogue.

The effect of geometrically rigid trans α,ß-unsaturated ε-amino acids on the structure, folding, and assembly of α,ε-hybrid peptide foldamers has been reported. From single-crystal diffraction analysis, the unsaturated tetrapeptide 1 has stapler-pin-like structure but without intramolecular hydrogen bond. The asymmetric unit has two molecules that are stabilized by multiple intermolecular hydrogen bonding interactions as well as π-π stacking interactions between the aromatic rings of 3-aminocinnamic acid. Peptide 1 does not form organogel. But on hydrogenation, peptide 1 provides the saturated α,ε-hybrid peptide foldamer 2, which forms instant gel in most of the aromatic solvents. The gel exhibits high stability. The unsaturated peptide 1 has porous microsphere morphology, but saturated analogue 2 has ribbonlike morphology. The gel has been used efficiently for removal of cationic organic pollutants from waste water.

Phenylalanine and derivatives as versatile low-molecular-weight gelators: design, structure and tailored function.

Phenylalanine (Phe) is an essential amino acid classified as neutral and nonpolar due to the hydrophobic nature of the benzyl side chain. In the field of materials science, the chemical modification of phenylalanine at C or N terminus has enabled to synthesize a large number of low-molecular-weight gelators over the past decade. Thus, many physical (or supramolecular) softgel materials have been fabricated by self-assembly of Phe-derived building blocks, which can be programmed with atomic level information and modification. The process of self-assembly and gelation must balance the parameters that influence the solubility as well as the contrasting forces that dictate epitaxial growth into entangled fibrillar aggregates. Gelator-gelator and solvent-gelator interactions are known to be highly important for the gelation process, and the non-covalent nature of these interactions provides physical gels with important properties such as reversible phase transitions and responsiveness towards external stimuli. Among other applications, these gels have been used for drug delivery, as extracellular matrix for tissue engineering, for oil spills recovery, removal of dyes, extraction of heavy metals or pollutants, and for the detection of explosives. In this tutorial review, we highlight the advances in the design, synthesis and applications of supramolecular gels made of Phe and derivatives.

On-line Ammonia Sensor and Invisible Security Ink by Fluorescent Zwitterionic Spirocyclic Meisenheimer Complex.

Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex. This excellent photoluminescent (PL) Meisenheimer complex has two distinct stimuli responsive sites. One is sensitive towards acid while the other one is towards the base. These two positions can be modulated by adding one equivalent acid and one equivalent base to result two new products which are non fluorescent. One of these two non fluorescent species was found very exciting because of its UV/Vis transparency. Utilizing this concept we have fabricated an on-line sensor for measuring ammonia in dry or humid and condensing sewer air. The sensor was robust against ambient temperature and humidity variation. We have also developed an invisible ink from this Meisenheimer complex, with potential application for security purpose.

Mopping up the Oil, Metal, and Fluoride Ions from Water.

The recycle, cleaning, and reuse of water are highly important for environmental remediation. This issue is addressed by creating a fluorescent zwitterionic spirocyclic Meisenheimer complex with high chelating propensity for toxic metals using low-cost starting materials and a one-pot synthesis technique. The resulting material is able to detect fluoride up to 12.8 ppb level and remove 82% aqueous fluoride from 1000 mL of 100 ppm fluoride solution in a single contact. The material demonstrates rapid kinetics and is capable of dropping the toxic metal ion (Pb/Hg/Cd) concentration below 0.2 ppb within 10 min. A resin-free, precipitation-free, and reusable technique has been developed for the removal of toxic metal ions and fluoride from extremely polluted water. Moreover, utilizing its extreme hydrophobicity, polystyrene sponges have been coated with the Meisenheimer complex to mop up oil spill and organic solvents from a biphasic mixture.

Formation of toroids by self-assembly of an α-α corner mimetic: supramolecular cyclization.

An α-α corner mimetic self-assembles to form a rod-like supramolecular structure which bends and closes end-to-end like a cyclization reaction to form uniform toroids. Each peptide fragment containing l-leucine, α-aminoisobutyric acid (Aib) and l-tyrosine forms rigid 310 helical structures stabilized by multiple intramolecular N-HO hydrogen bonds. Two 310 helices are connected by the spacer 3-aminomethyl-benzylamine and maintain an angular distance of 120° and therefore mimic the α-α corner motif of a protein super secondary structure. The individual α-α corner subunits are themselves regularly interlinked through multiple water mediated intermolecular hydrogen-bonding interactions to form the rod-like supramolecular structure and toroids. The formation of the supramolecular structure has been proven with X-ray crystallography and other spectroscopic techniques. The cyclization of the supramolecular structure and toroid formation were studied by optical microscope, AFM and FE-SEM experiments. Despite other assignments such as exfoliation of graphene from graphite, the compound exhibits significant memory to finally produce the toroids.

M-Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces.

M-Au/TiO2 (M = Ag, Pd, Pt) composites were prepared through a facile one-pot photodeposition synthesis and evaluated for solar water splitting (SWS) with and without a sacrificial agent. The M-Au combination exhibits a dominant role in augmenting the H2 generation activity by forming a bi-metallic system. Degussa P25 was used as a TiO2 substrate to photodeposit Au followed by Au + M (M = Ag/Pd/Pt). The SWS activity of the M-Au/TiO2 was determined through photocatalytic H2 production in the presence of methanol as a sacrificial agent under one sun conditions with an AM1.5 filter. The highest H2 yield was observed for Pt0.5-Au1/TiO2 and was around 1.3 ± 0.07 mmol h(-1) g(-1), with an apparent quantum yield (AQY) of 6.4%. Pt0.5-Au1/TiO2 also demonstrated the same activity for 25 cycles of five hours each for 125 h. Critically, the same Pt0.5-Au1/TiO2 catalyst was active in overall SWS (OSWS) without any sacrificial agent, with an AQY = 0.8%. The amount of Au and/or Pt was varied to obtain the optimum composition and it was found that the Pt0.5-Au1/TiO2 composition exhibits the best activity. Detailed characterization by physico-chemical, spectral and microscopy measurements was carried out to obtain an in-depth understanding of the origin of the photocatalytic activity of Pt0.5-Au1/TiO2. These in-depth studies show that gold interacts predominantly with oxygen vacancies present on titania surfaces, and Pt preferentially interacts with gold for an effective electron-hole pair separation at Pt-Au interfaces and electron storage in metal particles. The Pt in Pt0.5-Au1/TiO2 is electronically and catalytically different from the Pt in Pt/TiO2 and it is predicted that the former suppresses the oxygen reduction reaction.

Electronic control of interface ferromagnetic order and exchange-bias in paramagnetic-antiferromagnetic epitaxial bilayers.

The hetero-epitaxially engineered magnetic phases, formed due to entanglement of the spin, charge and lattice degrees of freedom, at the atomically sharp interfaces of complex oxide heterostructures are indispensable for devising multifunctional devices. In the quest for novel and superior spintronics functionalities, we have explored the interface magnetism in the epitaxial bilayer of atypical magnetic and electronic states, i.e., of paramagnetic metallic and antiferromagnetic (AFM) insulating phases. In this framework, we observe an unusually strong ferromagnetic order and large exchange-bias fields generated at the interface of the bilayers of metallic CaRuO3 and AFM insulating manganite. The magnetic moment of the interface ferromagnetic order increases linearly with increasing thickness (7-90 nm) of the metallic CaRuO3 layer. This linear scaling signifying an electronic (non-magnetic) control of the interface magnetism and a non-monotonic dependence of the exchange-bias on metallic layers evolve as novel spintronics attributes in atypical bilayers.

Anomalous enhancement in interfacial perpendicular magnetic anisotropy through uphill diffusion.

We observed interfacial chemical sharpening due to uphill diffusion in post annealed ultrathin multilayer stack of Co and Pt, which leads to enhanced interfacial perpendicular magnetic anisotropy (PMA). This is surprising as these elements are considered as perfectly miscible. This chemical sharpening was confirmed through quantitative energy dispersive x-ray (EDX) spectroscopy and intensity distribution of images taken on high angle annular dark field (HAADF) detector in Scanning Transmission Electron Microscopic (STEM) mode. This observation demonstrates an evidence of miscibility gap in ultrathin coherent Co/Pt multilayer stacks.

Emergence of nanoscale inhomogeneity in the superconducting state of a homogeneously disordered conventional superconductor.

The notion of spontaneous formation of an inhomogeneous superconducting state is at the heart of most theories attempting to understand the superconducting state in the presence of strong disorder. Using scanning tunneling spectroscopy and high resolution scanning transmission electron microscopy, we experimentally demonstrate that under the competing effects of strong homogeneous disorder and superconducting correlations, the superconducting state of a conventional superconductor, NbN, spontaneously segregates into domains. Tracking these domains as a function of temperature we observe that the superconducting domains persist across the bulk superconducting transition, Tc, and disappear close to the pseudogap temperature, T*, where signatures of superconducting correlations disappear from the tunneling spectrum and the superfluid response of the system.

Conjugation of cytochrome c with hydrogen titanate nanotubes: novel conformational state with implications for apoptosis.

We show that hydrogen titanate (H(2)Ti(3)O(7)) nanotubes form strongly associated reversible nano-bio-conjugates with the vital respiratory protein, cytochrome c. Resonance Raman spectroscopy along with direct electrochemical studies indicate that in this nano-bio-conjugate, cytochrome c exists in an equilibrium of two conformational states with distinctly different formal redox potentials and coordination geometries of the heme center. The nanotube-conjugated cytochrome c also showed enhanced peroxidase activity similar to the membrane-bound protein that is believed to be an apoptosis initiator. This suggests that such a nanotube-cytochrome c conjugate may be a good candidate for cancer therapy applications.

Structure and chemistry across interfaces at nanoscale of a Ge quantum well embedded within rare earth oxide layers.

Structure and chemistry across the rare earth oxide-Ge interfaces of a Gd2O3-Ge-Gd2O3 heterostructure grown on p-Si (111) substrate using encapsulated solid phase epitaxy method have been studied at nanoscale using various transmission electron microscopy methods. The structure across both the interfaces was investigated using reconstructed phase and amplitude at exit plane. Chemistry across the interfaces was explored using elemental mapping, high-angle annular dark-field imaging, electron energy loss spectroscopy, and energy dispersive X-ray spectrometry. Results demonstrate the structural and chemical abruptness of both the interfaces, which is most essential to maintain the desired quantum barrier structure.