Möbius Aromatic Core‐Modified Heterocyclic [20] Macrocycles (4.1.1) with a Protruding N‐Methyl Pyrrole Ring

Herein, we report the first synthesis of an unorthodox tripyrrane moiety from the regioselective β‐benzoylation of pyrrole and the acid‐catalyzed condensation of the desired precursors. A [3+1] Mac Donald type condensation strategy for this tripyrrane has led to the exclusive isolation of two hitherto‐unknown aromatic [20] heterocyclic macrocycles (4.1.1).     

Superb hydroxyl radical-mediated biocidal effect induced antibacterial activity of tuned ZnO/chitosan type II heterostructure under dark

Journal of Nanoparticle Research - With the widespread use of titanium dioxide (TiO2) human exposure is inevitable, but the exposure data on TiO2 are still limited. This study adopted off-line...     

Retention of enzymatic activity of alpha-amylase in the reductive synthesis of gold nanoparticles

In this paper, we report the generation of Au nanoparticles (NPs), using a pure enzyme for the reduction of AuCl4(-), with the retention of enzymatic activity in the complex. As a model system, alpha-amylase was used to readily synthesize and stabilize Au NPs in aqueous solution. Although several other enzymes were also pursued for the synthesis, it was interesting to observe that only alpha-amylase and EcoRI could produce Au NPs. Following NP synthesis, the activity of the enzyme was retained in the Au NP-alpha-amylase complex. The presence of Au NPs and alpha-amylase in the complex was established by UV-visible and FT-IR spectroscopy, X-ray diffraction (XRD) and transmission electron microscopic (TEM) measurements. Our observations suggest that the presence of free and exposed S-H groups is essential in the reduction of AuCl4(-) to Au NPs. Structural analysis of the enzymes showed that both alpha-amylase and EcoRI enzymes have free and exposed S-H groups in their native form and thus are suitable for the generation of NPs, whereas the other ones used here do not have such groups. Fortuitously, the enzymatic functional group of alpha-amylase is positioned opposite to that of the free and exposed S-H group, which makes it ideal for the production of Au NPs; binding of the enzyme to Au NPs via Au-S bond and also retention of the biological activity of the enzyme.     

Synthesis of ladder polymers containing polydiacetylene backbones connected with methylene chains and their optical properties

The polymers consisting of polydiacetylene (PDA) backbones were obtained from the novel monomer derivatives, R CC CC R′ CC CC R [where R =  (CH₂)₄OCONHCH₂COOC₄H₉, R′ =  (CH₂)_n ; n = 2, 4, 8] [4BCMU4A(n)], in which linear methylene chain is sandwiched between two diacetylene moieties by solid-state 1,4-addition reaction. The polymerization process was investigated in detail by using spectroscopic techniques such as solid-state ¹³C-NMR, visible absorption, and IR absorption spectra. It was estimated that the polymerization of 4BCMU4A(8) and 4BCMU4A(4) takes place by two consecutive 1,4-addition reactions to form two PDA backbones, which constitute the two poles of the respective ladders. The bridging methylene chain length in the monomer was found to play a vital role as far as the polymerization process is concerned. Thus, the monomers with eight or four methylene units could form the ladder–PDAs by a two-step process, whereas the monomer containing two methylene units could only undergo one-step of 1,4-addition reaction. Further, it was found that the crystallinity of the polymers depends on the methylene chain length in the monomers, 4BCMU4A(8) being the most crystalline of all. These structural features strongly affect their absorption spectra. The third-order nonlinear optical susceptibilities (χ⁽³⁾) for these polymers were measured using third-harmonic generation method. The largest χ⁽³⁾ value obtained was 3.4 × 10⁻¹¹ esu for the poly[4BCMU4A(8)] thin film in resonant region. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3537–3548, 1999     

Structural, electronic and magnetic properties of Cr-doped (ZnTe)12 clusters

We have studied the energetics and magnetism in Cr-doped (ZnTe)₁₂ clusters by first principles density functional calculations. Total energy calculations suggest that it is energetically most favourable for Cr atoms to substitute at Zn sites. Both ferromagnetic and anti-ferromagnetic coupling between the Cr atoms exist depending on the Cr-Cr distance in the clusters. The magnetic exchange coupling between Cr atoms is short-ranged.     

The mass hierarchy with atmospheric neutrinos at INO

We study the neutrino mass hierarchy at the magnetized Iron CALorimeter (ICAL) detector at India-based Neutrino Observatory with atmospheric neutrino events generated by the Monte Carlo event generator Nuance. We judicially choose the observables so that the possible systematic uncertainties can be reduced. The resolution as a function of both energy and zenith angle simultaneously is obtained for neutrinos and anti-neutrinos separately from thousand years un-oscillated atmospheric neutrino events at ICAL to migrate number of events from neutrino energy and zenith angle bins to muon energy and zenith angle bins. The resonance ranges in terms of directly measurable quantities like muon energy and zenith angle are found using this resolution function at different input values of θ₁₃${\theta }_{13}$. Then, the marginalized χ²s${\chi }^2\mathrm{s}$ are studied for different input values of θ₁₃${\theta }_{13}$ with its resonance ranges taking input data in muon energy and zenith angle bins. Finally, we find that the mass hierarchy can be explored up to a lower value of θ₁₃≈5°${\theta }_{13}\approx 5°$ with confidence level >95% in this set up.     

An economic and environmental comparison of a biochemical and a thermochemical lignocellulosic ethanol conversion processes

With the world’s focus on rapidly deploying second generation biofuels technologies, there exists today a good deal of interest in how yields, economics, and environmental impacts of the various conversion processes of lignocellulosic biomass to transportation fuels compare. Although there is a good deal of information regarding these conversion processes, this information is typically very difficult to use on a comparison basis because different underlying assumptions, such as feedstock costs, plant size, co-product credits or assumed state of technology, have been utilized. In this study, a rigorous comparison of different biomass to transportation fuels conversion processes was performed with standard underlying economic and environmental assumptions so that exact comparisons can be made. This study looked at promising second-generation conversion processes utilizing biochemical and thermochemical gasification technologies on both a current and an achievable state of technology in 2012. The fundamental finding of this study is that although the biochemical and thermochemical processes to ethanol analyzed have their individual strengths and weaknesses, the two processes have very comparable yields, economics, and environmental impacts. Hence, this study concludes that based on this analysis there is not a distinct economic or environmental impact difference between biochemical and thermochemical gasification processes for second generation ethanol production.     

Multiscale spatial Monte Carlo simulations: multigriding, computational singular perturbation, and hierarchical stochastic closures

Monte Carlo (MC) simulation of most spatially distributed systems is plagued by several problems, namely, execution of one process at a time, large separation of time scales of various processes, and large length scales. Recently, a coarse-grained Monte Carlo (CGMC) method was introduced that can capture large length scales at reasonable computational times. An inherent assumption in this CGMC method revolves around a mean-field closure invoked in each coarse cell that is inaccurate for short-ranged interactions. Two new approaches are explored to improve upon this closure. The first employs the local quasichemical approximation, which is applicable to first nearest-neighbor interactions. The second, termed multiscale CGMC method, employs singular perturbation ideas on multiple grids to capture the entire cluster probability distribution function via short microscopic MC simulations on small, fine-grid lattices by taking advantage of the time scale separation of multiple processes. Computational strategies for coupling the fast process at small length scales (fine grid) with the slow processes at large length scales (coarse grid) are discussed. Finally, the binomial tau-leap method is combined with the multiscale CGMC method to execute multiple processes over the entire lattice and provide additional computational acceleration. Numerical simulations demonstrate that in the presence of fast diffusion and slow adsorption and desorption processes the two new approaches provide more accurate solutions in comparison to the previously introduced CGMC method.