Liquid phase microextraction applications in food analysis

Over the last years, liquid-phase microextraction (LPME) in its different application modes (single drop microextraction, dispersive liquid-liquid microextraction and hollow fiber-LPME) has been increasingly applied for the extraction of both inorganic and organic analytes from different matrices. Its advantages over conventional extraction procedures (simplicity, effectiveness, rapidity and low consumption of organic solvents) has also attracted its application in the complex food analysis field, in which it has clearly provided good and challenging results. A comprehensive review dealing with those articles published since its introduction till the end of March 2011 is presented, offering also a critical vision of the analytical potential of LPME for the analysis of foods.     

Acylation of Quercetin with a Novel Thermophilic Esterase as Biocatalyst

The regioselective acylation of quercetin catalyzed by a novel thermophilic esterase(APE1547)from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents.The effects of acyl don...     

A simple and sensitive assay for apurinic/apyrimidinic endonuclease 1activity based on host-guest interaction of β-cyclodextrin polymer and pyrene

A simple and sensitive method for APE1 activity detection was developed based on fluorescence enhancement of pyrene in the presence of β-cyclodextrin polymer.     

Annurca peel extract: from the chemical composition,through the functional activity,to the formulation and characterisation of a topical oil-in-water emulsion

The aim of this study was to produce a hydro-alcoholic safe antioxidant Malus pumila Miller cv Annurca peel extract (APE) useful as functional ingredient in an oil-in-water emulsion. Results showed that APE contains a hydroxycinnamic acid (chlorogenic acid), flavonol glycosides (quercetin derivatives) and a dihydrochalcone, phloridzin (phloretin-2-O-glucoside). The isoquercitrin (quercetin-3-O-glucoside) content was quantified in 0.3% w/w of extract. APE showed a significant and concentration-dependent free-radical scavenging activity correlated to its polyphenols content. No cytotoxic effect was observed in primary human epidermal keratinocyte adults and dermal fibroblast cell lines. The formulative approach led to produce a stable emulsion able to load a high amount of APE, up to 6.0% w/w. The homogenous distribution of APE in the emulsion was clearly demonstrated by fluorescence microscopy analysis. The emulsion resulted able to enhance the in vitro release rate of APE through synthetic membranes with respect to the raw material.     

Model selection and prediction: Normal regression

This paper discusses the topic of model selection for finite-dimensional normal regression models. We compare model selection criteria according to prediction errors based upon prediction with refitting, and prediction without refitting. We provide a new lower bound for prediction without refitting, while a lower bound for prediction with refitting was given by Rissanen. Moreover, we specify a set of sufficient conditions for a model selection criterion to achieve these bounds. Then the achievability of the two bounds by the following selection rules are addressed: Rissanen's accumulated prediction error criterion (APE), his stochastic complexity criterion, AIC, BIC and the FPE criteria. In particular, we provide upper bounds on overfitting and underfitting probabilities needed for the achievability. Finally, we offer a brief discussion on the issue of finite-dimensional vs. infinite-dimensional model assumptions.Support from the National Science Foundation, grant DMS 8802378 and support from ARO, grant DAAL03-91-G-007 to B. Yu during the revision are gratefully acknowledged.     

Study of Vacuum Structure by Low-Lying Eigenmodes of Overlap-Dirac Operator

APE smearing and overlap-Dirac operator are combined to filter vacuum configurations. The structures of vacuum are studied by low-lying eigenmodes of the overlap-Dirac operator, which exhibits that instanton liquid model can be used.     

超嗜热酯酶APE1547中特殊位置氢键对酶活力和热稳定性的影响

探讨了APE1547蛋白的β-推进器结构中第3和第4“叶片”间的侧链氢键(Thr127-Gly154, Leu182-Arg145-Glu122)对蛋白质的作用.     

Development of a parallel molecular dynamics code on SIMD computers: Algorithm for use of pair list criterion

In recent years several implementations of molecular dynamics (MD) codes have been reported on multiple instruction multiple data (MIMD) machines. However, very few implementations of MD codes on single instruction multiple data (SIMD) machines have been reported. The difficulty in using pair lists of nonbonded interactions is the major problem with MD codes for SIMD machines, such that, generally, the full connectivity computation has been used. We present an algorithm, the global cut-off algorithm (GCA), which permits the use of pair lists on SIMD machines. GCA is based on a probabilistic approach and requires the cut-off condition to be simultaneously verified on all nodes of the machine. The MD code used was taken from the GROMOS package; only the routines involved in the pair lists and in the computation of nonbonded interactions were rewritten for a parallel architecture. The remaining calculations were performed on the host computer. The algorithm has been tested on Quadrics computers for configurations of 32, 128, and 512 processors and for systems of 4000, 8000, 15,000, and 30,000 particles. Quadrics was developed by Istituto Nazionale di Fisica Nucleare (INFN) and marketed by Alenia Spazio. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 685–694, 1998