A strategy for screening trypsin inhibitors from traditional Chinese medicine based on a monolithic capillary immobilized enzyme reactor coupled with offline liquid chromatography and mass spectrometry

A novel strategy was successfully developed for screening trypsin inhibitors in traditional Chinese medicines based on monolithic capillary immobilized enzyme reactors combined with liquid chromatography‐tandem mass spectrometry. Organic polymer based monolithic enzyme reactors were firstly prepared by covalently bonding trypsin to a poly(glycidyl methacrylate‐co‐poly (ethylene glycol) diacrylate) monolith by the ring‐opening reaction of epoxy groups. The activity and kinetic parameters of the obtained monolithic trypsin reactors were systematically evaluated using micro‐liquid chromatography. Fourier transform infrared spectroscopy and scanning electron microscopy were also used to characterize the monolithic trypsin reactors. The resulting functional and denatured monolithic trypsin reactors were applied as affinity solid‐phase extraction columns, and offline coupled with a liquid chromatography‐tandem mass spectrometry system to construct a binding affinity screening platform. Subsequently, the proposed platform was applied for screening trypsin binders in a Scutellaria baicalensis Georgi extract. Three compounds, namely scutellarin, baicalin, and wogonoside were identified, and their inhibitory activities were further confirmed via an in vitro enzymatic inhibition assay. Additionally, molecular docking was also performed to study the interactions between trypsin and these three compounds.     

Synergistically Directed Assembly of Aromatic Stacks Based Metal‐Organic Frameworks by Donor‐Acceptor and Coordination Interactions

A synergistically directed assembly approach to distinctive metal‐organic frameworks utilizing both donor‐acceptor (D‐A) interaction from aromatic systems and coordination interactions is presented. Based on such an approach, the coronene‐tpt (tpt = 2,4,6‐tri(4‐pyridyl)‐1,3,5‐triazine) stacks based coronene‐MOF‐1 — 4 have been successfully fabricated. Their structural discrepancies with coronene‐ absent control products, 1′ — 4′ , illustrate clearly the significance of coronene‐tpt based D‐A interactions in these architectures. All these coronene‐MOFs contain varied coronene‐tpt stacks as organic secondary building blocks (SBUs), which are closely interrelated with the coordination based framework structures. Moreover, porous coronene‐MOF‐1 and ‐2 exhibit high physicochemical stability and significant light hydrocarbons storage and separation performances.     

Fabrication of niobium doped titanate nanoflakes with enhanced visible-light-driven photocatalytic activity for efficient ibuprofen degradation

Niobium doping increases the visible light adsorption of titanate nanoflakes, which greatly enhances the photocatalytic activity for ibuprofen elimination.     

Gold nanoparticle-based monitoring of the reduction of oxidized to reduced glutathione

We demonstrate the reduction of oxidized to reduced glutathione in the presence of glutathione reductase enzyme based on the modulation in photoluminescent quenching efficiency between the perylene bisimide chromophore TPPCA and gold nanoparticles (AuNPs). The TPPCA-AuNPs assembly shows a turn-on fluorescent signal in the presence of reduced glutathione, which provides a new concept to measure the balance of glutathione in a creature.     

Importance sampling as a variational approximation

There is a well-recognized need to develop Bayesian computational methodologies that scale well to large data sets. Recent attempts to develop such methodology have often focused on two approaches—variational approximation and advanced importance sampling methods. This note shows how importance sampling can be viewed as a variational approximation, achieving a pleasing conceptual unification of the two points of view. We consider a particle representation of a distribution as defining a certain parametric model and show how the optimal approximation (in the sense of minimization of a Kullback-Leibler divergence) leads to importance sampling type rules. This new way of looking at importance sampling has the potential to generate new algorithms by the consideration of deterministic choices of particles in particle representations of distributions.     

Multimodal biometric authentication based on score level fusion of finger biometrics

In this article, we propose a novel finger multimodal biometric authentication that combines finger vein, fingerprint, finger shape and finger knuckle print features of a single human finger. The proposed multimodal biometrics provides score-level fusion approach based on triangular norm with four finger biometric traits, instead of two or three ones combined in the previous approaches. The experimental evaluations and analysis are conducted on a merged multimodal biometrics database. The results show that the proposed score-level fusion approach using triangular norm obtains a larger distance between genuine and imposter score distribution as well as achieves lower error rates. Moreover, the comparison results suggest that the proposed score level fusion of finger biometrics using triangular norm outperforms the state-of-the-art approaches.     

A kinetics-controlled coating method to construct 1D attapulgite @ amorphous titanium oxide nanocomposite with high electrorheological activity

A new kind of one-dimension attapulgite (APG) @ titanium oxide nanoparticles was prepared via kinetics-controlled coating method. By simply altering the ammonia content and reaction time to control the kinetics of hydrolysis and condensation of tetra-n-butyl titanate (TBOT) in ethanol/ammonia mixtures, amorphous titanium oxide nanoparticles can adhere to the APG rods firmly, and the thickness of uniform amorphous titanium oxide shells can be adjusted from 0 to 40 nm. The obtained APG@ titanium oxide nanorods were applied as a new electrorheological (ER) fluid, which showed a promising ER activity. The yield stresses of the APG@ titanium oxide nanorod (40-nm shell thickness) ER fluid under electric field was 2.1 times of the granular titanium oxide ER fluid and 4.1 times of the APG ER fluid. And, the APG@ titanium oxide nanorod ER fluid also exhibited distinctly improved suspended stability.     

Synthesis of the AB subunit of angelmicin B through a tandem alkoxy radical fragmentation-etherification sequence

The synthesis of the tricyclic enone 2, corresponding to the AB subunit of the novel tyrosine kinase inhibitor angelmicin B, is described. The strategy centers on an intramolecular Diels-Alder (IMDA) reaction on triene 4 to provide the complex decalin 3, which is elaborated to 2. Other key steps are the formation of the THF ring in 2 through a tandem alkoxy radical fragmentation-etherification on the lactol derived from 3, and the synthesis of 4 via a ring-closing ene-yne metathesis (RCEYM).     

Visible near-infrared chemosensor for mercury ion

A visible near-infrared chemosensor (MCy-1) for mercury ions was successfully devised and characterized. A large red-shift (122 nm) of the absorption maximum of MCy-1 was observed. An important feature for the new chemosensor is its high selectivity towards mercury ions over the other competitive species, making the "naked-eye" detection of mercury ions possible.     

Asymptotic profiles of the endemic equilibrium of a diffusive SIS epidemic system with saturated incidence rate and spontaneous infection

A susceptible‐infected‐susceptible (SIS) epidemic reaction‐diffusion model with saturated incidence rate and spontaneous infection is considered. We establish the existence of endemic equilibrium by using a fixed‐point theorem. The global asymptotic stability of the constant endemic equilibrium is discussed in the case of homogeneous environment. We mainly investigate the effects of diffusion and saturation on asymptotic profiles of the endemic equilibrium. When the saturated incidence rate tends to infinity, the susceptible and infective distributes in the habitat in a nonhomogeneous way; this result is in strong contrast with the case of no spontaneous infection, where the endemic equilibrium tends to the disease free equilibrium. Our analysis shows that the spontaneous infection can enhance the persistence of an infectious disease and may provide some useful implications on disease control.