Simplifying curve skeletons in volume images

The curve skeleton of a 3D solid object provides a useful tool for shape analysis tasks. In this paper, we use a recent skeletonization algorithm based on voxel classification that originates a nearly thin, i.e., at most two-voxel thick, curve skeleton. We introduce a novel way to compress the nearly thin curve skeleton to one-voxel thickness, as well as an efficient pruning algorithm able to remove unnecessary skeleton branches without causing excessive loss of information. To this purpose, the pruning condition is based on the distribution of significant elements along skeleton branches. The definition of significance depends on the adopted skeletonization algorithm. In our case, it is derived from the voxel classification used during skeletonization.     

Biodegradability of Free Monomeric and Cell-Wall-Bound Phenolic Acids in Maize Stover by Two Strains of White-Rot Fungi

Development of fungal bioconversion technology to upgrade feeding value of fibrous crop residues into animal feed requires the understanding of the impact of fungal treatments on cell wall phenolic acids. This study investigated the capacity of two strains of white-rot fungi, Phanerochaete chrysosporium and Phlebia brevispora , in degrading cell wall-bound phenolic acids in maize ( Zea maize L) stover and the free phenolic monomers in a liquid culture medium. In the study, 150 mg litre⁻¹ of p -coumaric acid (PCA), ferulic acid (FA), syringic acid (SYA), p -hydroxybenzoic acid (PHBA), vanillic acid (VA), and 200 mg litre⁻¹ of caffeic acid (CA) were added to a liquid nutrient medium and incubated with each of the fungi for 28 days. The results indicated that within 21 days the fungal treatments completely removed the added PCA and FA from the medium, and over 94% of SYA was degraded after 28 days. During the incubation periods, VA and PHBA were also extensively removed by P chrysosporium , but resistant to degradation by P brevispora . Disappearance of caffeic acid from the medium was related to both fungal degradation and abiotic hydrolysis. In the culture media, P chrysosporium was superior to P brevispora in removing the phenolic acids. Solid incubation of maize stover with the selected fungi for 28 days resulted in extensive degradation of cell-wall-bound FA and PCA. However, complete degradation of cell wall FA and PCA did not occur in maize stover. In contrast to results in pure liquid medium, P chrysosporium degraded only 20% of the initial concentration of cell wall PCA, and was less effective in degrading cell wall FA compared to P brevispora . These results indicate that the white-rot fungi were able to degrade phenolic acids both in pure culture medium and in cell wall matrix of maize stover. Furthermore, P brevispora exhibited stronger ability to degrade cell-wall-bound phenolic acids. Thus, this fungus can be more effective for the enhancement of fibre digestibility.     

Fusarium mycotoxins in cereals harvested from Hungarian fields

The Fusarium mycotoxins deoxynivalenol (DON), zearalenone (ZEN) and T-2 frequently contaminate grain crops in Middle and Eastern Europe. In this survey, 116 cereal samples (maize, wheat, barley and oat) were examined for DON, ZEN and T-2 mycotoxins. Samples were collected from different areas in two Hungarian regions (North and South Transdanubia). The method of analysis was indirect competitive ELISA. Maize was the most contaminated grain regarding DON (86%), ZEN (41%) and T-2 (55%) toxins. The average results of the deoxynivalenol and zearalenone tests of maize proved to be significantly higher than those of barley or oat. DON was the most represented Fusarium mycotoxin followed by T-2 and ZEN. The examination of these mycotoxins would be necessary at a larger scale as to re-evaluate permissible levels, so increase of the monitoring programme would be advisable for the future.     

Shiga‐Toxin Genes and Genetic Diversity of Escherichia coli Isolated from Pasteurized Cow Milk in Brazil

This study evaluated the genetic similarity and prevalence of the stx1, stx2, eae, and ehxA genes in Escherichia coli isolated from pasteurized cow milk. Eighty‐seven E. coli isolates from pasteurized cow milk from 22 dairies located in northwestern Paraná state, Brazil, were analyzed. Genetic similarity was evaluated using enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC‐PCR) and repetitive extragenic palindromic sequence PCR (REP‐PCR). E. coli isolates were also analyzed by PCR to investigate the presence of the stx1, stx2, eae, and ehxA genes. ERIC‐PCR and REP‐PCR clustered 87 bacterial isolates in 76 and 81 genomic profiles, respectively. Both techniques revealed high genetic diversity among the E. coli isolates, confirming the possibility of their use in epidemiological studies. The stx1, stx2, eae, and ehxA virulence genes were not detected in E. coli isolates, indicating a low prevalence of Shiga toxin‐producing E. coli in milk produced in the region studied.     

Effect of In Vitro Digestion on Free α‐Dicarbonyl Compounds in Balsamic Vinegars

We investigated the influence of an in vitro simulated digestion process on the content of the free α‐dicarbonyl compounds most frequently found in food. A Glyoxal (GO), methylglyoxal (MGO), and diacetyl (DA) aqueous standard mixture and 2 brands of balsamic vinegar were analyzed before and after exposure to digestive enzymes. A strong matrix effect required adoption of validated RP‐HPLC‐DAD standard addition methods. The results showed that the digestive enzymes markedly alter the concentrations of the exogenous free α‐dicarbonyl compounds ingested with food; the extent of such changes varied with the α‐dicarbonyl compound itself and the diet components, which determined important but different food matrix effects also during digestion. The data also indicate that digestion can reduce the bioavailability of the toxic α‐dicarbonyl compounds ingested with food. However, no firm conclusions can be drawn about a putative positive influence of digestion on the toxic potential of dietary α‐dicarbonyl compounds, because their reaction in the presence of digestive enzymes likely gives rise to advanced glycation end products, which are involved in the development of chronic diseases.     

Characterization of olive oil produced with a new enzyme processing aid

By carrying out olive oil extraction experiments with three olive varieties (Dritta, Coratina, and Leccino), a new processing cytolase enzyme aid was tested. The oils, obtained with the enzyme adjuvant upon extraction, were characterized (with respect to reference oils) by: (i) relatively higher content of natural antioxidants (free and linked phenols, ortho-diphenols, tocopherols), trans-2-hexenal, total aromatic substances, chlorophyllic pigments, and steroid hydrocarbons; (ii) slightly lower content of aliphatic alcohols, triterpene alcohols, triterpene dialcohols, β-sitosterol, and total sterols; (iii) slightly higher values of integral color index, resistance to autoxidation, and global quality indices; (iv) lower values of carotenoid color index, alcoholic index and some qualitative ratios, such as trans-2-hexenal/hexanal, trans-2-hexenal/total aroma, campesterol/stigmasterol; and (v) a higher sensory score. Hence, they exhibited better overall qualitative characteristics. The enzyme adjuvant, in addition, led to higher oil extraction outputs.     

A flexible approach to evaluating soft conditions with unequal preferences in fuzzy databases

A flexible model for evaluating soft query with unequal preferences in fuzzy databases is proposed. We assume that conditions with unequal preferences have an exclusive meaning like in the request “find a holiday accommodation such that big apartments are preferred to high rating hotels.” In this case it is assumed that the aggregator of the soft conditions is an implicit OR. Conversely, conditions with unequal importance have an inclusive meaning, like in the query “find a house to rent that is cheap (most important), big (important), new (fairly important).” In this case the implicit aggregator is an AND. What we propose in this article is to model preferences as modifiers of the semantics of the evaluation function of the conditions. Because the soft conditions are aggregated by an OR, the more a soft condition is preferred, the more its evaluation function tolerates a greater undersatisfaction of the soft condition. The proposed approach is formalized by considering two alternative semantics of the evaluation function: the first semantics defines the evaluation function by means of a generalized fuzzy inclusion measure, and the second one as a generalized similarity measure. These functions are parameterized so that their modification is simply achieved by tuning the functions' parameters. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 665–689, 2007.     

Isotope systematics of C-bearing gas compounds in the geothermal fluids of Larderello, Italy

The origin of carbon-bearing compounds (CO₂, CH₄, C₂–C₄ saturated hydrocarbons) and helium in the geothermal fluid of Larderello is investigated by means of the variations in concentration and isotopic composition. The CO₂ (δ¹³C from −1.4 to −7.1‰ versus V-PDB) is mainly of crustal origin. The carbon isotopes of methane (δ¹³C from −20.9 to −31.7‰) and other hydrocarbons indicate a complex thermogenic origin. The temperatures obtained with the CH₄–CO₂ isotope geothermometer are in rough agreement with those observed in deeper geothermal wells. The CH₄/C₂H₆ ratios show a tendency towards partial equilibrium with increasing temperature. He isotopes (R/R_A from 0.5 to 3) indicate that although the major part of helium derives from crustal sources, a significant fraction of mantle helium is also present. Helium contamination by air, deducted from He/Ne ratios, is generally negligible.     

Microfluidic chip for continuous monitoring of hormone secretion from live cells using an electrophoresis-based immunoassay

A microfluidic device has been developed for the determination of insulin secreted from islets of Langerhans by a capillary electrophoresis competitive immunoassay. Online assays were performed by electrophoretically sampling anti-insulin antibody (Ab), fluorescein isothiocyanate-labeled insulin (FITC-insulin), and insulin from separate reservoirs and allowing them to mix as they traveled through a 4-cm reaction channel heated to 38 degrees C. From the reaction channel, samples were injected onto a 1.5-cm-long electrophoresis channel where the FITC-insulin and FITC-insulin-Ab complex were separated in 5 s using an electric field of 500 V/cm. Detection limits for insulin were 3 nM in this mode of operation. Assays could be collected at 15-s intervals with continuous sampling and online mixing for up to 30 min with no intervention. Relative standard deviation was 2-6% depending on the insulin concentration. Response time to a step change in insulin concentration was 30 s. For live cell monitoring, single islets were placed into a reservoir on the chip and fluid in the immediate vicinity was continuously sampled to detect insulin secretion from the islet. Monitoring of insulin secretion with electropherograms taken at 15-s intervals resolved secretory profiles characteristic of first- and second-phase insulin secretion. The method should be amenable to other cell or tissue types for measurements of release with high temporal resolution.