End fixity in cold-formed steel sections using press joining

Connections in cold formed steel structures using multiple press joins can develop moment resistance. This paper describes and presents the results of a series of tests on cold formed steel C sections with multiple press joined connections. The experimental results are compared with similar tests on simply supported and pinned end connected beams and the degree of partial fixity is assessed. The failure load can be predicted using plastic analysis techniques.     

The shear behaviour of press-joining in cold-formed steel structures

This paper describes a relatively new joining technique for cold formed steel structures called press joining. Press joining is a technique whereby a joint is created from the sheets to be connected, requiring no additional fixing items. A series of shear test results are given.The effect of UTS, steel thickness and angle of inclination of the join on both strength and deformation characteristics of the press join are discussed.A theoretical expression based on the results is developed linking all of the influencing factors to the shear strength of the join.     

Catalytic isoforms Tpk1 and Tpk2 of Candida albicans PKA have non‐redundant roles in stress response and glycogen storage

Candida albicans cAMP‐dependent protein kinase (PKA) is coded by two catalytic subunits (TPK1 and TPK2) and one regulatory subunit (BCY1). In this organism the cAMP/PKA signalling pathway mediates basic cellular processes, such as the yeast‐to‐hyphae transition and cell cycle regulation. In the present study, we investigated the role of C. albicans PKA in response to saline, heat and oxidative stresses as well as in glycogen storage. To fine‐tune the analysis, we performed the studies on several C. albicans PKA mutants having heterozygous or homozygous deletions of TPK1 and/or TPK2 in a different BCY1 genetic background. We observed that tpk1Δ/tpk1Δ strains developed a lower tolerance to saline exposure, heat shock and oxidative stress, while wild‐type and tpk2Δ/tpk2Δ mutants were resistant to these stresses, indicating that both isoforms play different roles in the stress response pathway. We also found that regardless of the TPK background, heterozygous and homozygous BCY1 mutants were highly sensitive to heat treatment. Surprisingly, we observed that those strains devoid of one or both TPK1 alleles were defective in glycogen storage, while strains lacking Tpk2 accumulated higher levels of the polysaccharide, indicating that Tpk1 and Tpk2 have opposite roles in carbohydrate metabolism. Copyright © 2009 John Wiley & Sons, Ltd.     

Adsorption equilibria of benzodiazepines on a hybrid polymeric chiral stationary phase

The chromatographic behavior of a series of racemic benzodiazepines was evaluated under linear and nonlinear conditions on a new hybrid polymeric (DACH-ACR) chiral stationary phase (CSP). Differently substituted benzodiazepines were employed as probes to make hypotheses concerning possible molecular interaction mechanisms originating between target compounds and active sites on the CSP. Hydrogen bonds were found to be pivotal for chromatographic retention and chiral selectivity. The competitive effect from a mobile-phase (MP) modifier able to interact with the CSP through H-bonds was investigated. The performance of the polymeric DACH-ACR CSP for preparative purposes was also evaluated. The competitive adsorption isotherms of two benzodiazepines, lorazepam and temazepam, were measured at different MP compositions through the so-called inverse method. The adsorption data were fitted with a competitive bi-Langmuir adsorption isotherm. Enantiomeric separations under nonlinear conditions were modeled by using the equilibrium dispersive (ED) model of chromatography. Theoretical overloaded band profiles (obtained by solving the system of partial differential equations described by the ED model) matched, in a significantly accurate way, the profiles experimentally measured.     

Transparent exopolymeric particles' distribution in the northern Adriatic and their relation to microphytoplankton biomass and composition

Transparent exopolymer particles (TEP) are generated during transformation processes within the non-living organic matter continuum in the seawater. Seasonal dynamics of TEP along the Po River Delta-Rovinj transect was followed during the 3-year period, using a spectrophotometric method of determination of TEP. Relationships between TEP and phytoplankton biomass (chlorophyll a), abundance and composition, as well as phaeophytin, were analysed. Microphytoplankton spring blooms are confirmed to be an important source of TEP, with some species more related to TEP concentration dynamics, such as Chaetoceros sp. and Skeletonema costatum. Notable spatial west to east gradient of autotrophic biomass and consequently of TEP was observed, as well as gradual decrease with depth. In addition, TEP concentration increments were observed up to 2 months before the mucilage events followed by the decrease of TEP concentration during the event itself. Pattern of TEP dynamics in the years with mucilage events was the most pronounced in 2002, when the event was spatially and temporally the most extended.     

Color of Salmon Fillets By Computer Vision and Sensory Panel

A computer vision method was developed and used to assign color score in salmon fillet according to SalmonFan™ card. The methodology was based on the transformation of RGB to L*a*b* color space. In the algorithm, RGB values assigned directly to each pixel by the camera in the salmon fillet image, were transformed to L*a*b* values, and then matched with other L*a*b* values that represent a SalmonFan score (between 20 and 34). Colors were measured by a computer vision system (CVS) and a sensorial panel (eight panelists) under the same illumination conditions in ten independent sets of experiments. Errors from transformation of RGB to L*a*b* values by the CVS were 2.7%, 1%, and 1.7%, respectively, with a general error range of 1.83%. The coefficient of correlation between the SalmonFan score assigned by computer vision and the sensory panel was 0.95. Statistical analysis using t test was performed and showed that there were no differences in the measurements of the SalmonFan score between both methods (t _c = 1.65 ≤ t = 1.96 at α = 0.05%). The methodology presented in this paper is very versatile and can potentially be used by computer-based vision systems in order to qualify salmon fillets based on color according to the SalmonFan card.     

Characteristics of Convective Drying of Pepino Fruit (Solanum muricatum Ait.): Application of Weibull Distribution

The aim of this research was to study the behaviour of the drying kinetics of pepino fruit (Solanum muricatum Ait.) at five temperatures (50, 60, 70, 80 and 90 °C). In addition, desorption isotherms were determined at 20, 40 and 60 °C over a water activity range from 0.10 to 0.90. The Guggenheim, Anderson and de Boer model was suitable to depict the desorption data. A monolayer moisture content from 0.10 to 0.14 g water g⁻¹ d.m. was reported. The equations of Newton, Henderson–Pabis, Modified Page, Wang–Singh, Modified Henderson–Pabis, Logarithmic as well as standardised Weibull were tested for modelling drying kinetics. Besides, Fick’s second law model was used to calculate the water diffusion coefficient which increased with temperature from 2.55 to 7.29 × 10⁻¹⁰ m² s⁻¹, with estimated activation energy of 27.11 kJ mol⁻¹. The goodness of fit of the models was evaluated using sum squared error and chi-square statistical tests. The comparison of the experimental moisture values with respect to the calculated values showed that the standardised Weibull model presented the best goodness of fit, showing that this equation is very accurate for simulating drying kinetics for further optimisation of drying times.     

Acrylamide reduction in potato chips by using commercial asparaginase in combination with conventional blanching

In this research acrylamide reduction in potato chips was investigated in relation to blanching and asparaginase immersion treatments before final frying. Potatoes slices (Verdi variety, diameter: 40 mm, thickness: 2.0 mm) were fried at 170 °C for 5 min (final moisture content of ∼2.0 g/100 g). Prior to frying, potato slices were treated in one of the following ways: (i) Rinsing in distilled water (control I); (ii) Rinsing in distilled water plus blanching in hot water at 85 °C for 3.5 min; (iii) Rinsing in distilled water plus immersion in an asparaginase solution (10000 ASNU/L) at 50 °C for 20 min; (iv) Rinsing in distilled water plus blanching in hot water at 85 °C for 3.5 min plus immersion in an asparaginase solution (10000 ASNU/L) at 50 °C for 20 min; (v) Rinsing in distilled water plus blanching in hot water at 85 °C for 3.5 min plus immersion in distilled water at 50 °C for 20 min (control II). Blanching in hot water (ii) was almost as effective as asparaginase potato immersion (iii) in order to diminish acrylamide formation in potato chips (acrylamide reduction was ∼17% of the initial acrylamide concentration). When potato slices were blanched before asparaginase immersion, the acrylamide content of the resultant potato chips was reduced considerably by almost 90%. We have demonstrated that blanching of potato slices plus asparaginase treatment is an effective combination for acrylamide mitigation during frying. It seems to be that blanching provokes changes in the microstructure of potato tissue leading to an easier and more effective diffusion of asparaginase.