Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal–dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

Optics naturally provides us with some powerful mathematical operations. Here, we experimentally demonstrate that during reflection or refraction at a single optical planar interface, the optical computing of spatial differentiation can be realized by analyzing specific orthogonal polarization states of light. We show that the spatial differentiation is intrinsically due to the spin Hall effect of light and generally accompanies light reflection and refraction at any planar interface, regardless of material composition or incident angles. The proposed spin-optical method takes advantages of a simple and common structure to enable vectorialfield computation and perform edge detection for ultrafast image processing.

A simple and efficient biphasic system with an earth-abundant metal salt catalyst was used to produce furfural from xylan with a high yield of up to 87.8 % under microwave conditions. Strikingly, the metal salt Al (SO ) exhibited excellent catalytic activity for xylan conversion, owing to a combination of Lewis and Brønsted acidity and its ability to promote good phase separation. The critical role of the SO anion was first analyzed, which resulted in the aforementioned characteristics when combined with the Al cation. The mixed solvent system with γ-valerolactone (GVL) as the organic phase provided the highest furfural yield, resulting from its good dielectric properties and dissolving capacity, which facilitated the absorption of microwave energy and promoted mass transfer. Mechanistic studies suggested that the xylan-to-furfural conversion proceeded mainly through a hydrolysis-isomerization-dehydration pathway and the hexa-coordinated Lewis acidic [Al(OH) (aq)] species were the active sites for xylose-xylulose isomerization. Detailed kinetic studies of the subreaction for the xylan conversion revealed that GVL regulates the reaction rates and pathways by promoting the rates of the key steps involved for furfural production and suppressing the side reactions for humin production. Finally, the Al (SO ) catalyst was used for the production of furfural from several lignocellulosic feedstocks, revealing its great potential for other biomass conversions.

ABSTRACT:This article describes an in vitro investigation of the inhibition of cytochrome P450 (P450) 2C9 by a series of flavonoids made up of flavones (flavone, 6-hydroxyflavone, 7-hydroxyflavone, chrysin, baicalein, apigenin, luteolin, scutellarein, and wogonin) and flavonols (galangin, fisetin, kaempferol, morin, and quercetin). With the exception of flavone, all flavonoids were shown to inhibit CYP2C9-mediated diclofenac 4-hydroxylation in the CYP2C9 RECO system, with K i value <2.2 M. In terms of the mechanism of inhibition, 6-hydroxyflavone was found to be a noncompetitive inhibitor of CYP2C9, whereas the other flavonoids were competitive inhibitors. Computer docking simulation and constructed mutants substituted at residue 100 of CYP2C9.1 indicate that the noncompetitive binding site of 6-hydroxyflavone lies beside Phe100, similar to the reported allosteric binding site of warfarin. The other flavonoids exert competitive inhibition through interaction with the substrate binding site of CYP2C9 accessed by flurbiprofen. These results suggest flavonoids can participate in interactions with drugs that act as substrates for CYP2C9 and provide a possible molecular basis for understanding cooperativity in human P450-mediated drug-drug interactions.Flavonoids are polyphenolic secondary metabolites that are widely distributed in higher plants and ingested by humans in their regular food (Kuhnau, 1976;Bravo, 1998). Flavones and flavonols are two major classes of flavonoids (Table 1). Flavonols are present in a variety of fruits and vegetables, whereas flavones are mainly found in cereals and herbs (Hertog et al., 1993;Bravo, 1998;Peterson and Dwyer, 1998). In the West, the estimated daily intake of both flavonols and flavones is in the range 20 to 50 mg per day (Cermak and Wolffram, 2006). However, given the growing demand for food supplements or herbal remedies containing flavonoids, and given that in some countries flavonoids are commonly used as therapeutic agents (2008 State Food and Drug Administration RPC, http://app1.sfda.gov. cn/datasearch/face3/dir.html), it is likely that some individuals are exposed to relatively high levels of flavonoids. This points to a need for more information on the safety and potential toxicity of flavonoids.In the early 1980s, several studies reported the effects of flavonoids on the activity of hepatic cytochrome P450 (P450) enzymes (Buening et al., 1981;Lasker et al., 1982). Since then, the ability of flavonoids to inhibit isoforms of CYP450, particularly CYP1A1 and CYP1A2, has been extensively confirmed (Cermak and Wolffram, 2006). Several clinical studies have reported that some flavonoids have the capacity to alter drug metabolism in vivo (Peng et al., 2003;Rajnarayana et al., 2003;Choi et al., 2004). However, for CYP2C9, which ranks among the most important drug-metabolizing enzymes in humans and hydroxylates 10 to 20% of commonly prescribed drugs (Kirchheiner and Brockmöller, 2005), only two flavones, luteolin and baicalein, and one flavonol, quercetin, have been found to ...

Here, we report fabrication of two-dimensional (2D) lead monoxide (PbO) nanosheets by facile liquid phase exfoliation. The as-prepared 2D PbO nanosheets have circle and cut-circle shapes with a lateral dimension range of 200−400 nm and a thickness range of 10−15 nm and exhibit dominant β-crystals with a robust chemical stability under ambient conditions. As a building block, the 2D PbO has been developed for photoelectrochemical (PEC)-type photodetectors that exhibited excellent as well as tunable photoresponse behaviors under illuminations of ultraviolet−visible lights. The first-principles density functional theory calculations further show that the band gap (E g ) of 2D PbO can be tuned by external electric field with a significant Stark effect. Moreover, differing from most transition metal dichalcogenide (TMD) materials, the 2D PbO structure, whose lowest empty states are dominated by the lead p orbitals, is exposed, which means that orbital modification of 2D PbO is accessible. Consequently, the E g of PbO can be decreased in the KOH electrolyte by a possible Pb−OH interaction, thus, broadening its absorption range for photodetection applications. In addition, the photoresponse behavior of 2D PbO-based photodetectors has long-term stability. This work may open the way for development of 2D PbO nanomaterials with promising applications.

Zinc dithiophosphate (DTP) molecules have long been used as wear inhibitor oil additives for automotive engines. In order to obtain an atomistic understanding of the mechanism by which these molecules inhibit wear, we examined the geometries, energetics, and vibrations of an oxidized iron surface [(001) surface of α-Fe2O3] using the MSX force field (FF) based on ab initio quantum chemistry (QC) calculations. The DTP molecules studied include (RO)2PS2 with R = methyl, isobutyl, isopropyl, and phenyl. The α-Fe2O3 surface is described using the generalized valence bond (GVB) model of bonding. The geometries, binding energies, and vibrational frequencies from ab initio calculations on simple clusters are used with the biased Hessian method to develop the MSX FF suitable for describing the binding of DTP molecules to the surfaces. We find that the cohesive energies for the self-assembled monolayers (SAM) of the DTP molecules on the Fe2O3 surface correlate with the antiwear performance observed in experimental engine tests. This suggests that the search for more effective and environmentally benign wear inhibitors can use the cohesive energies for SAM formation as a criterion in selecting and prioritizing compounds for experimental testing.

Green-Kubo relations for the mutual diffusion coefficients of an n-component system are derived from hydrodynamic equations, linear response theory, and the statistical theory of fluctuations. The mutual diffusion coefficients, which form an (n -1)-dimensional matrix, are formulated as a product of a kinetic matrix and a thermodynamic matrix. The kinetic matrix consists of time integrals of diffusion flux correlation functions, i.e., the Onsager phenomenological coefficients. The thermodynamic matrix is determined by spatial integrals of radial distribution functions. The formulas are derived initially in the barycentric reference frame and then transformed to the volume-fixed reference frame, which is more appropriate to laboratory studies. Explicit expressions for binary and ternary mixtures are presented, from which various empirical relations between the mutual diffusion coefficients and self-diffusion coefficients are obtained using particular assumptions regarding the velocity cross-correlation functions. Assuming zero values for certain combinations of the cross-correlation functions yields the Darken or Hartley-Crank equation for binary systems and Cooper's diffusion model for ternary systems, while assigning negative values to these combinations results in Lasaga's relation, which is a special case of the so-called common force diffusion model.

No abstract