Discrete Quantum Causal Dynamics

We give a mathematical framework to describe the evolution of open quantum systems subject to finitely many interactions with classical apparatuses and with each other. The systems in question may be composed of distinct, spatially separated subsystems which evolve independently, but may also interact. This evolution, driven both by unitary operators and measurements, is coded in a mathematical structure in such a way that the crucial properties of causality, covariance, and entanglement are faithfully represented. The key to this scheme is the use of a special family of spacelike slices—we call them locative—that are not so large as to result in acausal influences but large enough to capture nonlocal correlations.     

Electronic structure of hydrogen and muonium in Al,Mg and Cu

The electronic structure of hydrogen and muonium in simple metals is investigated. The spherical solid model potential is used for the discrete lattice and the Blatt correction for lattice dilation. The proton and muon are kept at the octahedral sites in the fcc and hcp lattices and self-consistent non-linear screening calculations are carried out. The scattering phase shifts, electronic charge density, effective impurity potential, self-energy, charge transfer, residual resistivity and Knight shift are calculated. The spherical solid potential changes the scattering character of impurity. The phase shifts are found slowly converging. The scattering is more prominent in Al than in Mg and Cu. The virtual bound states of proton and muon are favoured in all the three metals. The calculated value of residual resistivity for CuH is in good agreement with the experimental value. The results for Knight shift forμ ⁺ in Cu and Mg are in reasonable agreement with the experimental values while those forμ ⁺ in Al are lower than the experimental value. The analytical expressions for effective impurity potential and electronic charge density are suggested.     

Synthesis and discovery of N-(1-methyl-4-oxo-4,5-dihydro-1H-imidazol-2-yl)-[1,1′-biphenyl]-2-carboxamide derivatives as antimicrobial agents

Novel dihydro-1H-imidazole-2-yl)-[1,1′-biphenyl]-2-carboxamides ( 4a-l ) was achieved using a three-step synthesis process and evaluated as antimicrobial agents. These compounds were characterized through FTIR, NMR, LCMS and evaluated for DNA gyrase inhibition potentials and antimicrobial properties against Gram-negative bacteria Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 424), Klebsiella pneumoniae MTCC 530 and Gram-positive bacteria Staphylococcus aureus (MTCC 3160), Corynebacterium diphtheriae (MTCC 116) and Streptococcus pyogenes (MTCC 442). Excellent DNA gyrase inhibition exhibited by compound 4f (IC₅₀ 0.2 μM and relative percentage activity 96.24%). A broad spectrum of antimicrobial activity showed by compounds 4d , 4f and 4 k with a Minimal Inhibitory Constant (MIC) of 1.05, 1.35 and 1.25 μg mL⁻¹, respectively.     

Continuous Flow Reactor for the Controlled Synthesis and Inline Photocatalysis of Antibacterial Ag2S Nanoparticles

The present study is focused on the integration of microreactors to synthesize visible light active nanophotocatalysts for inline photocatalytic degradation of organic dye and antibacterial activity. A wire-assisted and a rapid laser micromachining technique has been employed for the fabrication of polydimethylsiloxane (PDMS) and poly(methyl methacrylate) (PMMA)-based microreactors, respectively. By varying the design and chemical reagents involved, different sizes of visible light active Ag₂S nanoparticles were prepared via a continuous microfluidics approach using fabricated microreactors. When polyvinylpyrrolidone (PVP) was utilized as the capping agent during the reaction, smaller particles of the size of ~ 15 nm were observed. The photocatalytic performance of these nanoparticles has been evaluated inline by employing the single-inlet planar microreactor as a function of flow rate and channel length. The photocatalyst durability test and a comparative photocatalytic efficiency study between the microreactor and the conventional beaker reactor have also been carried out. Under visible light, these nanoparticles exhibit a remarkable enhancement of ~ 94.5% in the inline microreactor-based photocatalytic degradation of methylene blue dye. The slower the flow rate and longer the channel length, gradual enhancement in the performance has been observed. Also, these nanoparticles express an antibacterial effect with very high efficacy even at very low (2 mg mL⁻¹) concentration toward the inhibition of Escherichia Coli.     

Hot Branching Dynamics in a Light-Harvesting Iron Carbene Complex Revealed by Ultrafast X-ray Emission Spectroscopy

Iron N-heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub-ps X-ray spectroscopy study of an Fe^IINHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot ³MLCT state, from the initially excited ¹MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the ³MC state, in competition with vibrational relaxation and cooling to the relaxed ³MLCT state. The relaxed ³MLCT state then decays much more slowly (7.6 ps) to the ³MC state. The ³MC state is rapidly (2.2 ps) deactivated to the ground state. The ⁵MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the ³MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition-metal complexes for similar ultrafast decays to optimize photochemical performance.     

Single‐Molecule Mechanochemical Sensing Using DNA Origami Nanostructures

While single‐molecule sensing offers the ultimate detection limit, its throughput is often restricted as sensing events are carried out one at a time in most cases. 2D and 3D DNA origami nanostructures are used as expanded single‐molecule platforms in a new mechanochemical sensing strategy. As a proof of concept, six sensing probes are incorporated in a 7‐tile DNA origami nanoassembly, wherein binding of a target molecule to any of these probes leads to mechanochemical rearrangement of the origami nanostructure, which is monitored in real time by optical tweezers. Using these platforms, 10 pM platelet‐derived growth factor (PDGF) are detected within 10 minutes, while demonstrating multiplex sensing of the PDGF and a target DNA in the same solution. By tapping into the rapid development of versatile DNA origami nanostructures, this mechanochemical platform is anticipated to offer a long sought solution for single‐molecule sensing with improved throughput.     

Long‐Lived Trifluoromethanide Anion: A Key Intermediate in Nucleophilic Trifluoromethylations

The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylation reactions. However, for more than six decades, the trifluoromethanide anion was widely believed to exist only as a short‐lived transient species in the condensed phase. It has now been prepared in bulk for the first time in THF solution. The trifluoromethanide anion with the [K(18‐crown‐6)]⁺ cation was unequivocally characterized by low‐temperature ¹⁹F and ¹³C NMR spectroscopy. Its intermediacy in nucleophilic trifluoromethylation reactions was directly evident by its reaction chemistry with various electrophilic substrates. Variable‐temperature NMR spectroscopy, along with quantum mechanical calculations, support the persistence of the trifluoromethanide anion.