Solvent Adaptive Dynamic Metal‐Organic Soft Hybrid for Imaging and Biological Delivery

A solvent responsive dynamic nanoscale metal‐organic framework (NMOF) [Zn( 1 a )(H₂O)₂] has been devised based on the self‐assembly of Zn^II and asymmetric bola‐amphiphilic oligo‐(p‐phenyleneethynylene) (OPE) dicarboxylate linker 1 a having dodecyl and triethyleneglycolmonomethylether (TEG, polar) side chains. In THF solvent, NMOF showed nanovesicular morphology ( NMOF‐1 ) with surface decorated dodecyl chains. In water and methanol, NMOF exhibited inverse‐nanovesicle ( NMOF‐2 ) and nanoscroll ( NMOF‐3 ) morphology, respectively, with surface projected TEG chains. The pre‐formed NMOFs also unveiled reversible solvent responsive transformation of different morphologies. The flexible NMOF showed cyan emission and no cytotoxicity, allowing live cell imaging. Cisplatin (14.4 wt %) and doxorubicin (4.1 wt %) were encapsulated in NMOF‐1 by non‐covalent interactions and, in vitro and in vivo drug release was studied. The drug loaded NMOFs exhibited micromolar cytotoxicity.     

Optimal harvesting and complex dynamics in a delayed eco-epidemiological model with weak Allee effects

In this article, an eco-epidemiological system with weak Allee effect and harvesting in prey population is discussed by a system of delay differential equations. The delay parameter regarding the time lag corresponds to the predator gestation period. Mathematical features such as uniform persistence, permanence, stability, Hopf bifurcation at the interior equilibrium point of the system is analyzed and verified by numerical simulations. Bistability between different equilibrium points is properly discussed. The chaotic behaviors of the system are recognized through bifurcation diagram, Poincare section and maximum Lyapunov exponent. Our simulation results suggest that for increasing the delay parameter, the system undergoes chaotic oscillation via period doubling. We also observe a quasi-periodicity route to chaos and complex dynamics with respect to Allee parameter; such behavior can be subdued by the strength of the Allee effect and harvesting effort through period-halving bifurcation. To find out the optimal harvesting policy for the time delay model, we consider the profit earned by harvesting of both the prey populations. The effect of Allee and gestation delay on optimal harvesting policy is also discussed.     

A novel route for in-situ H2O2 generation from selective reduction of O2 by hydrazine using heterogeneous Pd catalyst in an aqueous medium

Hydrogen peroxide in high yields can be generated with high efficiency at mild conditions (25 degrees C and atmospheric pressure) with the formation of only environment-friendly by-products (N2 and H2O) by a reduction of O2 by hydrazine from its hydrate/salt with its complete conversion in a short reaction period (相似文献   

Modified factorization method and supersymmetric quantum mechanics

We suggest a modified factorization scheme within a supersymmetric framework which affords a consistent treatment of a wide class of Schrödinger potentials. A consequence of this is the possibility of deriving a boson-fermion Hamiltonian with linear interaction.     

Kinetics and mechanism of the oxidation of ethylene glycol, 2,3-butanediol and pinacol by hexachloroiridate(IV)

Summary The kinetics of oxidation of ethylene glycol, 2,3-butanediol and pinacol have been studied spectrophotometrically under different experimental conditions. The reactions seem to occur through the formation of an intermediate complex between each diol and iridium(IV). The complexes decompose through intermediate free radicals to form formaldehyde, acetaldehyde and acetone, respectively. Thermodynamic parameters have been calculated.     

A note on uniform strong convergence of bivariate density estimates

In this paper we consider a class of estimates of a bivariate density function f based on an independent sample of size n. Under the assumption that f is uniformly continuous, the uniform strong consistency of such estimates was first proved by Nadaraya (1970) for a large class of kernel functions. In this note we show that the assumption of the uniform continuity of f is necessary for this type of convergence.     

Transition Metal‐Catalysed Direct C−H Bond Functionalizations of 2‐Pyridone Beyond C3‐Selectivity

2‐Pyridone is a ubiquitous motif in natural products, drug molecules, ligands in catalysis and organic materials. There is a necessity of direct step‐economic methods for the construction of 2‐pyridone based molecules. Strategically, the primary developments have led to the C3‐functionalizations due to the inherent reactivity of this center. Despite this, many elegant transition metal‐catalysed methods have been established to introduce versatile functional groups at the C4, C5 and C6‐position via direct C?H bond functionalizations. This minireview focuses on the categorized introduction of different functional groups at the 2‐pyridone scaffolds beyond C3‐selectivity and discusses substrate scope, limitations and plausible mechanistic details.     

Photoinduced C-Br homolysis of 2-bromobenzophenones and Pschorr ring closure of 2-aroylaryl radicals to fluorenones

A variety of diversely substituted 2-aroylaryl radicals, generated by photoinduced homolysis of 2-bromoarylketones, is shown to undergo Pschorr cyclization to yield fluorenones in moderate to excellent yields. The photochemical results illustrate that the substituents in the two phenyl rings of the 2-bromobenzophenone skeleton exert a dramatic influence on the reactivity of the derived 2-aroylaryl radicals. The disubstitution by methoxy groups in the radical ring renders the aryl sigma-radical highly electrophilic and unreactive for hydrogen abstraction and cyclization. On the other hand, the substituents in the non-radical ring that strongly stabilize the hydrofluorenyl pi-radical, formed subsequent to the attack of the 2-aroylaryl radical on the non-radical ring, promote cyclization to furnish fluorenones in excellent isolated yields.     

Integrated magnetic bionanocomposites through nanoparticle-mediated assembly of ferritin

Magnetic (FePt) and nonmagnetic (Au) nanoparticles were used to assemble ferritin into near-monodisperse bionanocomposites featuring regular interparticle spacing. The FePt/ferritin assemblies are integrated magnetic materials with ferritin providing added magnetic volume fraction to the magnetic nanocomposite. These assemblies differ from either of their constituent particles in terms of blocking temperature (TB), net magnetic moment, coercivity, and remnance.     

Canopy spectral invariants, Part 2: Application to classification of forest types from hyperspectral data

Many studies have been conducted to demonstrate the ability of hyperspectral data to discriminate plant dominant species. Most of them have employed the use of empirically based techniques, which are site specific, requires some initial training based on characteristics of known leaf and/or canopy spectra and therefore may not be extendable to operational use or adapted to changing or unknown land cover. In this paper we propose a physically based approach for separation of dominant forest type using hyperspectral data. The radiative transfer theory of canopy spectral invariants underlies the approach, which facilitates parameterization of the canopy reflectance in terms of the leaf spectral scattering and two spectrally invariant and structurally varying variables—recollision and directional escape probabilities. The methodology is based on the idea of retrieving spectrally invariant parameters from hyperspectral data first, and then relating their values to structural characteristics of three-dimensional canopy structure. Theoretical and empirical analyses of ground and airborne data acquired by Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over two sites in New England, USA, suggest that the canopy spectral invariants convey information about canopy structure at both the macro- and micro-scales. The total escape probability (one minus recollision probability) varies as a power function with the exponent related to the number of nested hierarchical levels present in the pixel. Its base is a geometrical mean of the local total escape probabilities and accounts for the cumulative effect of canopy structure over a wide range of scales. The ratio of the directional to the total escape probability becomes independent of the number of hierarchical levels and is a function of the canopy structure at the macro-scale such as tree spatial distribution, crown shape and size, within-crown foliage density and ground cover. These properties allow for the natural separation of dominant forest classes based on the location of points on the total escape probability vs the ratio log-log plane.