Sesquiterpene lactones and scopoletins from Artemisia scoparia Waldst. & Kit. and their angiotensin I-converting enzyme inhibitory activities

Food Science and Biotechnology - Ten compounds, including a new guaiane-type sesquiterpene lactone, were isolated from the aerial parts of Artemisia scoparia. The structure of the new compound was...     

Antimicrobial resistance and resistance genes in Escherichia coli strains isolated from commercial fish and seafood

The purpose of this study was to investigate the antimicrobial resistance and to characterize the implicated genes in Escherichia coli isolated from commercial fish and seafood. Fish and seafood samples (n=2663) were collected from wholesale and retail markets in Seoul, Korea between 2005 and 2008. A total of 179 E. coli isolates (6.7%) from those samples were tested for resistance to a range of antimicrobial agents. High rates of resistance to the following drugs were observed: tetracycline (30.7%), streptomycin (12.8%), cephalothin (11.7%), ampicillin (6.7%) and ticarcillin (6.1%). No resistances to amikacin, amoxicillin/clavulanic acid and cefoxitin were observed. Seventy out of 179 isolates which were resistant to one or more drugs were investigated by PCR for the presence of 3 classes of antimicrobial resistance genes (tetracycline, aminoglycosides and beta-lactams), class 1, 2 and 3 integrons. Gene cassettes of classes 1 and 2 integrons were further characterized by amplicon sequencing. The tetracycline resistance genes tetB and tetD were found in 29 (41.4%) isolates and 14 (20%) isolates, respectively. The beta-lactam resistance gene, bla(TEM) was found in 15 (21.4%) isolates. The aminoglycoside resistance gene, aadA was found in 18 (25.7%) isolates. Class 1 integron was detected in 41.4% (n=29) of the isolates, while only 2.9% (n=2) of the isolates were positive for the presence of class 2 integron. Two different gene cassettes arrangements were identified in class 1 integron-positive isolates: dfrA12-aadA2 (1.8 kb, five isolates) and aadB-aadA2 (1.6 kb, four isolates). One isolate containing class 2 integron presented the dfrA1-sat-aadA1 gene cassette array. These data suggest that commercial fish and seafood may act as the reservoir for multi-resistant bacteria and facilitate the dissemination of the resistance genes.     

Preparation of a hemiporous hydroxyapatite scaffold and evaluation as a cell-mediated bone substitute

A hemiporous hydroxyapatite (HAp) scaffold was prepared to support the tissue engineered approach to the restoration of damaged bone. The scaffold comprised a porous cell-seeded part and a non-porous load bearing part. A wet processing technique of HAp suspensions was used to shape the hemiporous body. The structure of the porous part was tailored using a stack of heat treated porogen placed on the plaster. The prepared specimen had approximately 30 layers of connected pores, which could accommodate sufficient human bone marrow stromal cells (hBMSCs). The result of an in vitro test showed that hBMSCs successfully proliferated and produced extracellular matrices even at the pore in the deep portion of the scaffolds. The in vivo test in the distal femur of a rabbit showed the formation of new fibrous tissue and tubular vessels with red blood cells in the hBMSCs-seeded scaffold from the pores at the deepest portion as well as from the pore at the periphery of the scaffold. The result was in distinct contrast with the scaffold without cell loading. The preloading of cell was thus very effective in the migration of cells in spite of the unconfirmed connectivity among pores. The present casting approach had the merits of simplicity and versatility in tailoring the scaffold structure without an elaborate device.     

Feasibility of laser-induced breakdown spectroscopy (LIBS) for classification of sea salts

We have investigated the feasibility of laser-induced breakdown spectroscopy (LIBS) as a fast, reliable classification tool for sea salts. For 11 kinds of sea salts, potassium (K), magnesium (Mg), calcium (Ca), and aluminum (Al), concentrations were measured by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and the LIBS spectra were recorded in the narrow wavelength region between 760 and 800 nm where K (I), Mg (I), Ca (II), Al (I), and cyanide (CN) band emissions are observed. The ICP-AES measurements revealed that the K, Mg, Ca, and Al concentrations varied significantly with the provenance of each salt. The relative intensities of the K (I), Mg (I), Ca (II), and Al (I) peaks observed in the LIBS spectra are consistent with the results using ICP-AES. The principal component analysis of the LIBS spectra provided the score plot with quite a high degree of clustering. This indicates that classification of sea salts by chemometric analysis of LIBS spectra is very promising. Classification models were developed by partial least squares discriminant analysis (PLS-DA) and evaluated. In addition, the Al (I) peaks enabled us to discriminate between different production methods of the salts.     

An enhanced CSLAM for multi-robot based on unscented kalman filter

This paper proposes an unscented Kalman filter (UKF) based coordinative, simultaneous localization and mapping (CSLAM) system, in which robots share common mapping information. The SLAM information obtained by a master robot is shared with slave robots, which estimate only their own localizations using comparatively simple sensors. The behavior of the slave robots depends on the reconstructed CSLAM using information transmitted by the master robot. The proposed process reduces the processing burden of the slave robots, which results in a reduction of the calculation time and the complexity of their hardware system. By comparing the proposed algorithm with some conventional methods in terms of system stability, the efficiency of the proposed method is verified.     

Rate-Independent and Rate-Dependent Models for Hysteretic Behavior of Elastomers

Rate-independent and rate-dependent models are presented for the hysteretic shear stress-strain behavior of elastomeric damping materials. A rate-independent hysteretic model, called the general asymptote and power function (GAPF) model, is presented that simulates different types of hysteretic behavior depending on the selected asymptote function. A rate-dependent hysteretic model, formed from a parallel combination of the GAPF model and a dashpot, is also presented which simulates loading frequency dependent behavior in addition to strain amplitude dependent behavior. Closed-form expressions for the shear stress as a function of shear strain are provided for each model. The models are calibrated for three different damping materials, and good correlation between experimental and analytical hysteretic behavior is observed. The models are investigated under variable cyclic loading. To prevent unrealistic stress values (overshooting) after a small strain reversal followed by reloading, a sequential asymptote model is introduced, based on the GAPF model. The hysteretic models were incorporated into a finite-element program within an elastomeric damper element, and the results of nonlinear time history analyses of a building structure with elastomeric dampers under simulated earthquake loading are presented to illustrate behavior of the hysteretic models under several loading histories.     

Dicaffeoylquinic acid derivatives and flavonoid glucosides from glasswort (Salicornia herbacea L.) and their antioxidative activity

Two novel antioxidant compounds, isoquercitrin 6″-O-methyloxalate (6) and methyl 4-caffeoyl-3-dihydrocaffeoyl quinate (salicornate, 7), were isolated from Salicornia herbacea L.. Six known compounds were also identified as 3,5-dicaffeoylquinic acid (1), quercetin 3-O-β-d-glucopyranoside (2), 3-caffeoyl-4-dihydrocaffeoylquinic acid (3), methyl 3,5-dicaffeoyl quinate (4), 3,4-dicaffeoylquinic acid (5), and isorhamnetin 3-O-β-d-glucopyranoside (8). Their chemical structures were determined by spectroscopic data from ESI–MS and NMR. The isolated dicaffeoylquinic acid derivatives (1, 3, 4, 5, and 7) showed similar activities for scavenging 1,1-diphenyl-2-picrylhydrazyl radicals and inhibiting formation of cholesteryl ester hydroperoxide during copper ion-induced rat blood plasma oxidation. The two flavonol glucosides (2 and 6), which have no substitutions in the B ring of their aglycones, also had similar activity. However, compound 8, which has the same structure as 2 except for the presence of a methoxyl group in the C-3′ position of the B ring, showed predominantly lower antioxidant activity than the other isolated compounds.     

Roasted garlic protects against leaky gut syndrome in dextran sodium sulfate-induced colitis mice

Food Science and Biotechnology - Garlic (Allium sativum) is a potentially beneficial functional food that is extensively grown around the globe. We have investigated the effect of roasted garlic on...     

Comparative study of antioxidant effects of five Korean varieties red pepper (Capsicum annuum L) extracts from various parts including placenta, stalk, and pericarp

Methanol extracts from the placenta, stalk, and pricarp of 5 Korean varieties red pepper (Capsicum annuum L) were obtained and antioxidant constituents including total phenol, total flavonoids, and capsaicin were analyzed. Antioxidant effects were determined by ABTS, DPPH, and nitric oxide (NO) free radicals scavenging activities and superoxide dismutase (SOD)-like activity. All the extracts showed strong antioxidant activities in various bioassays. Chromatic parameters (L*, a*, b*, C*, and Ho) were responsible for the antioxidant capacity of red pepper pericarp extracts. Generally, stalk been considered as disposable part, exhibited not only strong scavenging activities against free radicals, but also high content of total phenols, total flavonoids, and capsaicin. In addition, positive correlations were also observed between antioxidant activities and constituents of phenolics, flavonoids, and capsaicin. It was concluded that red pepper, including stalk, can be functional food materials to enhance human health.     

A new extraction method to determine bias-dependent source seriesresistance in GaAs FET's

A new method is proposed to determine bias-dependent source resistances for GaAs field-effect transistors (FET's). This method, which is a cold-FET measurement technique, utilizes the relations between the real part of the two-port impedances transformed from the measured S-parameters and their algebraic derivatives. It is based on the fact that the algebraic derivatives of the two-port resistances result in the simple form at the normal cold-FET condition. A bias-independent gate resistance is extracted at the pinched-off cold-FET condition to fulfill necessary and sufficient conditions in extraction. The proposed method is a direct measurement because only algebraic calculation is required, and it is general enough to need only one assumption of the laterally symmetric channel-doping profile. The deleterious results of dispersion (frequency dependence) and negative value in source resistances at the pinched-off cold-FET condition are explained by the effects of the leakage current and the on-wafer pad parasitics, respectively. The problem of deviation of α₂₁ and α₁₂ from 0.5 at the normal cold-FET condition is also resolved by deembedding the on-wafer pad parasitics. This method allows one to extract bias-dependent source resistances for GaAs FET's