Impact of initial moisture content levels,freezing rate and instant controlled pressure drop treatment (DIC) on dehydrofreezing process and quality attributes of quince fruits

Dehydrofreezing process involves water partial removal before freezing. This treatment has been proposed in order to reduce the negative impacts of conventional or even accelerated freezing, especially on the textural quality of high water content fruits and vegetables. Indeed, in such cases, freezing and thawing processes result in severe damage of the integrity of product’s cell structure due to the formation of ice crystals. For this purpose, quince fruits (7?g H₂O/g db) were subjected to convective air drying of 40?°C and 3m/s to reach different water content levels of 2, 1, and 0.3?g H₂O/g db. Freezing profiles obtained at various freezing rates (V₁, V₂, and V₃) for different water contents allowed the main freezing characteristics such as the Initial Freezing Temperature (IFT), the Practical Freezing time (PFt), and the Specific Freezing time (SFt) to be assessed. The impact of freezing rate was important on PFt and SFt, and more pronounced for high water contents (W between 7 and 2?g H₂O/g db (dry basis)). Furthermore, IFT decreased sharply when initial sample water content decreased. Indeed, it started at ?0.8?°C for W?=?7g H₂O/g db, while it reached a value of ?8.2?°C for samples of W?=?1g H₂O/g db. Since convective air drying normally triggers shrinkage which causes a detrimental deformation of fruit structures, instant controlled pressure drop (DIC) treatment was used to improve the texture and enhance the whole dehydrofreezing performance and the final frozen-thawed product quality. Moreover, DIC implied a slight increase of PFt compared to untreated ones. On the other hand, quality attributes were estimated through the assessment of thawed water exudate (TWE g H₂O/100?g db), color and texture (maximum puncture force as index of firmness): freezing rate and water content had great impacts on TWE. Hence, the lower the water content, the weaker the TWE. Furthermore, the TWE of the pre-dried quince (0.3?g H₂O/g db) had higher value for DIC-textured samples than for the un-treated ones. Indeed, DIC-texturing leads to a well-controlled structure expansion of the cell wall. These textural changes resulted in more lixiviation of residual water. Consequently, water becomes more available, hence more releasable after thawing. Finally, the partial removal of water by air drying before freezing remarkably reduced the negative impact of freezing/thawing processes on final quince color. Decisively, the firmness of quince fruit increased with the decrease of water content level.

Abbreviations: DMC: Dry Matter Concentration (%); DIC: Instant controlled pressure drop; W: Water content dry basis (g H₂O/g db); IFT: Initial Freezing Temperature (°C); PFt: Practical Freezing time (min); SFt: Specific Freezing time (min); TWE: Thawed Water Exudate (g H₂O/100?g db); L, a, and b: Color coordinates; (L): The degrees of lightness; (a) and (–a): The redness (a) or greenness (?a), respectively; (b) and (?b): The yellowness (b) or blueness (?b), respectively; ΔE*_ab: Total color difference; L₀, a₀, and b₀: Color coordinates of fresh or dried quince samples; SD: Standard Deviation; ANOVA: Analysis of variances; LSD: Least Significant Differences; cp: Specific Heat of the product depending on composition (dry material and water content)(KJ/kg K); cp_d: Specific Heat of the dry material (KJ/kg K); cp_W: Specific Heat of water (KJ/kg K); V₁: Freezing rate without insulation; V₂: Freezing rate with a food stretch film insulation with thickness e2?=?3?mm and thermal conductivity λ₂?=?0.17 W/m K; V₃: Freezing rate with a versatile flexible insulation (Armacell) with thickness e3?=?13mm and weak thermal conductivity λ₃?=?0.036 W/m K; v_d: Volume of dry material of quince sample (mm³); v_H2O: Volume of quince sample water (mm³); v_t: Total volume of quince sample (mm³); e₀: Quince sample thickness (mm); e₂: Insulation thickness in the case V2; = 3?mm; ; e₃: Insulation thickness in the case V3; = 13?mm; ; λ₀: Quince sample conductivity (W/m K); λ₂: Insulation conductivity in the case V2;?=?0.17 W/m K; ; λ₃: Insulation conductivity in the case V3;?=?0.036 W/m K; λ_d: Conductivity of quince sample dry material (W/m K); λ_H2O: Conductivity of water (W/m K); λ_equiv: Equivalent conductivity of quince sample versus water content (W/m K); m_i and m_f: Weights of the frozen and thawed samples, respectively     

Organophosphorus pesticide residues in Greek virgin olive oil: levels, dietary intake and risk assessment

The occurrence of organophosphorus pesticide (OPs) and their metabolite residues was investigated in 167 samples of Greek virgin olive oil during a 2-year (2004-2005) sampling campaign. A total of 30.5% of samples contained detectable residues, although only one sample contained dimethoate residues above the maximum residue limit. Among the seven detected OPs, fenthion and fenthion sulfoxide residues were detected in 10.8 and 14.4% of the samples, respectively, at levels of 0.003-0.61 mg kg(-1). Dimethoate was detected in 10.2% of the samples at 0.003-0.057 mg kg(-1). The acute dietary risk assessment was undertaken by determining the national estimated short-term intake (NESTI); for chronic dietary risk assessment, the national theoretical maximum daily intake (NTMDI) and national estimated daily intake (NEDI) were calculated. The estimated intakes (NESTI and NEDI) of each pesticide were <7 and <0.86% of the corresponding acute reference doses (ARfDs) and acceptable daily intakes (ADIs), respectively. A cumulative risk assessment was performed using the hazard index (HI) and toxicity equivalence factor (TEF), taking into account that OPs share the same toxicological mechanism. The determined HI and TEF values were found to represent only a small portion of the respective ADIs or ARfDs. These results indicate that there is neither acute nor chronic risk for the Greek population through olive oil consumption.     

Hygrothermal forced vibration of a viscoelastic laminated plate with magnetostrictive actuators resting on viscoelastic foundations

International Journal of Mechanics and Materials in Design - The article presents a vibration analysis of a laminated composite sandwich plate containing viscoelastic layers in the core and faces...     

Local commute-time guided MDS for 3D non-rigid object retrieval

In this paper, we propose a 3D non-rigid shape retrieval method based on canonical shape analysis. Our main idea is to transform the problem of non-rigid shape retrieval into a rigid shape retrieval problem via the well-known multidimensional scaling (MDS) approach and random walk on graphs. We first segment the non-rigid shape into local partitions based on its salient features. Then, we calculate a local MDS problem for each partition, where the local commute time distance is used as weighting function in order to preserve local shape details. Finally, we aggregate the set of local MDS problems as a global constrained problem. The constraint is formulated using the biharmonic function between local salient features. In contrast to MDS method, the proposed local MDS is computationally efficient, parameters free and gives isometry-invariant forms with minimum features distortion. Due to these advantageous properties, the proposed method achieved good retrieval accuracy on non-rigid shape benchmark datasets.     

Biological and technical variables affecting immunoassay recovery of cytokines from human serum and simulated vaginal fluid: a multicenter study

The increase of proinflammatory cytokines in vaginal secretions may serve as a surrogate marker of unwanted inflammatory reaction to microbicide products topically applied for the prevention of sexually transmitted diseases, including HIV-1. Interleukin (IL)-1beta and IL-6 have been proposed as indicators of inflammation and increased risk of HIV-1 transmission; however, the lack of information regarding detection platforms optimal for vaginal fluids and interlaboratory variation limit their use for microbicide evaluation and other clinical applications. This study examines fluid matrix variants relevant to vaginal sampling techniques and proposes a model for interlaboratory comparisons across current cytokine detection technologies. IL-1beta and IL-6 standards were measured by 12 laboratories in four countries, using 14 immunoassays and four detection platforms based on absorbance, chemiluminescence, electrochemiluminescence, and fluorescence. International reference preparations of cytokines with defined biological activity were spiked into (1) a defined medium simulating the composition of human vaginal fluid at pH 4.5 and 7.2, (2) physiologic salt solutions (phosphate-buffered saline and saline) commonly used for vaginal lavage sampling in clinical studies of cytokines, and (3) human blood serum. Assays were assessed for reproducibility, linearity, accuracy, and significantly detectable fold difference in cytokine level. Factors with significant impact on cytokine recovery were determined by Kruskal-Wallis analysis of variance with Dunn's multiple comparison test and multiple regression models. All assays showed acceptable intra-assay reproducibility; however, most were associated with significant interlaboratory variation. The smallest reliably detectable cytokine differences ( P < 0.05) derived from pooled interlaboratory data varied from 1.5- to 26-fold depending on assay, cytokine, and matrix type. IL-6 but not IL-1beta determinations were lower in both saline and phosphate-buffered saline as compared to vaginal fluid matrix, with no significant effect of pH. The (electro)chemiluminescence-based assays were most discriminative and consistently detected <2-fold differences within each matrix type. The Luminex-based assays were less discriminative with lower reproducibility between laboratories. These results suggest the need for uniform vaginal sampling techniques and a better understanding of immunoassay platform differences and cross-validation before the biological significance of cytokine variations can be validated in clinical trials. This investigation provides the first standardized analytic approach for assessing differences in mucosal cytokine levels and may improve strategies for monitoring immune responses at the vaginal mucosal interface.     

Effect of extraction conditions on the yield and purity of ulvan extracted from Ulva lactuca

A study of the influence of extraction conditions (pH: 1.5 and 2; temperature: 80 °C and 90 °C; extraction time: 1–3 h), on the yield, chemical composition and purity of the sulphated cell wall polysaccharides ulvan, extracted from the green seaweed Ulva lactuca and precipitated by alcohol is carried out. The alcohol precipitate yields varied from 21.68% to 32.67% (%dw/dw) depending on the pH. At pH 2, the alcohol precipitate yields and the uronic acid recovery from extract juice are higher than those obtained at pH 1.5. Other compounds than ulvan such as cellulose, hemicellulose, proteins and ash are solubilized from the cell walls of Ulva lactuca at both pH, and they are precipitated with alcohol. The alcohol precipitate obtained from different extraction conditions has high uronic acid (20.37%–23.60%) and neutral sugar content (20.09%–29.12%), especially when the conditions (pH, temperature) are drastic. It contains rhamnose (13.35%–15.59%), glucose (2.90%–10.97%), and xylose (2.36%–2.73%). A decrease in the molecular weight of ulvan was observed at acid pH, and for long extraction times. The presence of proteins (1.94%–2.32%) and inorganic material (33.36%–47.15%) in alcohol precipitate prove the lower purity of ulvan extracted and shows that ulvan precipitation with ethanol is not specific.     

Targeted Synthesis of Complex Spiro[3H-indole-3,2′-pyrrolidin]-2(1H)-ones by Intramolecular Cyclization of Azomethine Ylides: Highly Potent MDM2–p53 Inhibitors

Mouse double minute 2 (MDM2) is a main and direct inhibitor of the crucial tumor suppressor p53. Reports from initial clinical trials showed that blocking this interaction with a small-molecule inhibitor can have great value in the treatment of cancer for patients with p53 wild-type tumors; however, it also revealed dose-limiting hematological toxicities and drug-induced resistance as main issues. To overcome the former, an inhibitor with superior potency and pharmacokinetic properties to ultimately achieve full efficacy with less-frequent dosing schedules is required. Toward this aim, we optimized our recently reported spiro-oxindole inhibitors by focusing on the crucial interaction with the amino acid side chain of His96_MDM2. The designed molecules required the targeted synthesis of structurally complex spiro[indole-3,2′-pyrrolo[2,3-c]pyrrole]-2,4′-diones for which we developed an unprecedented intramolecular azomethine ylide cycloaddition and investigated the results by computational methods. One of the new compounds showed superior cellular potency over previously reported BI-0252. This finding is a significant step toward an inhibitor suitable to potentially mitigate hematological on-target adverse effects.     

A phase-field model for brittle fracture of anisotropic materials

In the present work, a phase field damage model is developed to address the numerical simulation of brittle fracture. This model successfully captures some important aspects of crack propagation, including crack branching and bifurcation. In addition, the proposed phase field model has been developed in the general framework of anisotropic elasticity. It can thus be used for the simulation of brittle fracture in polycrystalline materials, for which crack propagation is impacted by crystallographic orientation because of the anisotropic character of stiffness properties.     

Performance evaluation of legacy QCN for multicast and multiple unicast traffic transmission

A multicast congestion control scheme is an interesting feature to control group communication applications such as teleconferencing tools and information dissemination services. This paper addresses a comparison between multiple unicast and multicast traffic congestion control for Carrier Ethernet. In this work, we proposed to study the quantized congestion notification (QCN), which is a layer 2 congestion control scheme, in the case of multicast traffic and multiple unicast traffic. Indeed, the QCN has recently been standardized as the IEEE 802.1Qau Ethernet Congestion Notification standard. This scheme is evaluated through simulation experiments, which are implemented by the OMNeT++ framework. This paper evaluates the reaction point start time congestion detection, feedback rate, loss rate, stability, fairness and scalability performance of the QCN for multicast traffic transmission and multiple unicast traffic transmission. This paper also draws a parallel between QCN for multicast traffic transmission and that for multiple unicast traffic transmission. Despite the benefit of integrating the multicast traffic, results show that performance could degrade when the network scales up. The evaluation results also show that it is probable that the feedback implosion problem caused by the bottlenecks could be solved if we choose to set the queue parameter Qeq threshold value at a high value, 75% of the queue capacity for instance. Copyright © 2016 John Wiley & Sons, Ltd.