Limitations to schistosome growth and maturation in nonpermissive hosts

The life cycle of schistosomes is reviewed in its various steps, both in permissive hosts (in which the cycle is completed) and in nonpermissive hosts (which excrete no viable eggs as a result of the infection). A large worm loss occurs at (or after) the lung stage in both types of hosts (normal attrition) and some nonpermissive hosts (like the rat) have an additional elimination of worms from the portal circulation. Worm growth and reproductive maturation are also impaired in several nonpermissive hosts and the possible host-parasite interactions leading to such limitations are discussed, with special reference to hormonal influences. Attention is also given to peculiar phenomena occurring in some hosts, like the late portal worm elimination in rhesus monkeys, the migration from mesenteric veins to lungs in rats, and the block to egg excretion in guinea pigs. The steps of the schistosome life cycle which appear vulnerable in several hosts are contrasted with the steps which are carried out successfully in the majority of hosts studied.     

Temperature effects on DC and small signal RF performance of AlGaAs/GaAs HEMTs

We here report on the DC and microwave performance of HEMTs tested on wafer under different temperature conditions. The relevant experimental data show that the most important electrical parameters, such as the output current, the threshold voltage, the transconductance and the forward transmission coefficient, are sensibly affected by thermal phenomena. We focused our attention on the variations of the above parameters with the temperature because such a detailed knowledge is essential to establish the optimum bias point for a given application. Furthermore, we analyze the influence of the DC quiescent point degradations, due to thermal phenomena, on the small signal equivalent circuit. Since the thermal behavior of the circuit model is a function of the bias, we examine the behavior of the circuit elements vs. temperature over a wide range of bias conditions.     

Mammographic screening of the health district 38, hospital of Gardone Val Trompia (Brescia - Lombardy). Results of the first 2 rounds

The authors report the results of the first two rounds of a mammographic screening program by the Health District of Gardone Val Trompia (Brescia) including women 50 to 69 years old. 9,650 women were invited for round one and 6,415 (66.5%) attended; 9,656 were invited for round two and 6,552 (67.8%) attended. Fifty-four cancers were found in round one (detection rate: 8.4/1000): 11.1% of them were in situ carcinomas, 63% were T1 and 24.1% were T2 lesions, or higher. In round two, 32 lesions were detected (detection rate: 4.9/1000): 15.6% of them were in situ carcinomas, 78.1% were T1 and 3.2% were T2 lesions. In the positive cases axillary lymph nodes involvement was observed in 24.1% of cases in round one and was unknown in 27.8%, but the figures decreased to 6.2% and 9.4%, respectively, in round two. Effectiveness indicators were always observed.     

Metodo dei momenti per la soluzione di equazioni e sistemi di equazioni

Sommario In questa nota descriviamo una classe di possibili generalizzazioni del metodo della secaute per la soluzione di equazioni e di sistemi di equazioni, cui, per ragioni che risulteranno evidenti nel paragrafo 1.1., abbiamo dato il nome di metodo dei momenti. Vienes discusso l'ordine di convergenza e presentati alcuni esempi. Nel paragrafo 1.3., limitaitamente al caso della secante, viene dato un nuovo criterio per la scelta del punto da scartare dopo ogni iterazione, il quale offre notevoli vantaggi.

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In this paper we describe a class of possible generalization of the secant method for solving equations and systems of equations. To this class, for the reason illustrated in paragraph 1.1., we gave the name of the method of moments. The convergency order is discussed and some examples are introduced. In the paragraph 1.3., only for the sant case, a new criterion is given for the choice of the point to be discarded after every iterations. It offers some remarkable advantages.

     

Postharvest performance of fresh‐cut ‘Big Top’ nectarine as affected by dipping in chemical preservatives and packaging in modified atmosphere

Fresh‐cut ‘Big Top’ nectarines were dipped in 2% (w/v) ascorbic acid–1% (w/v) calcium lactate and stored at 4 °C for up to 12 days in 10 kPa O₂‐ and 10 kPa CO₂‐modified atmosphere packaging (MAP). The used microperforated plastic film allowed O₂ and CO₂ concentrations to reach steady values from the fifth day in storage onwards. Samples stored in MAP after chemical dipping showed the highest visual quality score, slight browning symptoms, increment in firmness and very low ethanol and acetaldehyde content. The chemical dipping also increased antioxidant capacity, probably due to the effect of ascorbic acid. The results suggested that the control of yeasts was mainly exerted by MAP, whereas only a slight effect was achieved by the chemical dipping. Therefore, MAP plus ascorbic acid/calcium lactate dipping was the best combination to preserve phytochemical content, antioxidant capacity and microbiological safety of fresh‐cut nectarines during storage.     

Comparison of bioactive phytochemical content and release of isothiocyanates in selected brassica sprouts

The consumption of brassica sprouts as raw vegetables provides a fair amount of glucosinolates (GLs) and active plant myrosinase, which enables the breakdown of GLs into health-promoting isothiocyanates (ITCs). This study reports the determination of the main constituents related to human health found in edible sprouts of two Brassica oleracea varieties, broccoli and Tuscan black kale, and two Raphanus sativus varieties, Daikon and Sango. Radish sprouts exhibited the highest ability to produce ITCs, with Daikon showing the greatest level of conversion of GLs into bioactive ITCs (96.5%), followed by Sango (90.0%). Tuscan black kale gave a value of 68.5%, whereas broccoli displayed the lowest with 18.7%. ITCs were not the exclusive GL breakdown products in the two B. oleracea varieties, since nitriles were also produced, thus accounting for the lower conversion observed. Measuring the release of plant ITCs is a valuable tool in predicting the potential level of exposure to these bioactive compounds after the consumption of raw brassica sprouts.     

A brief note on thermoluminescence analysis of photosystem II and lipid peroxidation during the shelf life of ready-to-use rocket (Diplotaxis tenuifolia L.)

The quality of leafy vegetables has to be guaranteed for consumers over the whole postharvest period, usually limited to 5–7 days. The analyses to evaluate the quality of vegetables are very time- and resource consuming, so the use of qualitative markers can be much useful. The aim of this work was to evaluate the use of thermoluminescence (TL) parameters as qualitative markers of fresh-cut leafy vegetables during the shelf life. TL is a technique consisting of a cooling, followed by the progressive warming, of a preilluminated sample to reveal the different types of charge pairs as successive emission bands, which are resolved better than the corresponding decay phases recorded at constant temperature. Experiments were performed on rocket (Diplotaxis tenuifolia L.) stored at 2 °C for 7 days. During storage, several changes in TL glow curves were found. The position of the peaks showed a shift to higher temperature. The area of the peaks, relating to the photosystem II (20–65 °C), grew up lightly; whereas in the temperature range that detects lipidic peroxidation (65–140 °C), the TL emission became more than twice. These changes demonstrated that, during the shelf life, a progressive destabilization of PSII centres occurred and that lipid peroxidation products were accumulated in membranes. TL could be used to estimate the damages immediately after as well as during the storage period. This is the first time that TL was used to evaluate the quality of fresh-cut vegetables products during the shelf life.     

New PEEK-WC and PLA membranes for H2 separation

The potentialities of PEEK-WC (thermally treated at 120 °C) and PLA polymers have been studied in the field of membrane technology applied to H₂ separation/purification. In particular, for low/medium temperature operation (80 °C), PEEK-WC membranes (66 μm thick) showed good results in terms of H₂/CH₄ separation, showing an ideal selectivity value higher than 40. Meanwhile, we observed interesting selectivity also for H₂/N₂ and H₂/CO₂ separation, reaching values of 24 and 20, respectively. As expected, for PEEK-WC thermally treated membranes, the H₂ permeating flux increased from 25 to 80 °C and by increasing the transmembrane pressure. Furthermore, H₂ permeability at 80 °C was around 20 barrer. Concerning PLA membranes (26 μm thick), it is worth of noting that this polymer was pioneeristically used in this work as membrane application, showing great results in terms of H₂/CO₂ separation. Indeed, we overcame the Robeson's upper-bound (2008), achieving an ideal selectivity H₂/CO₂ around 25 with an H₂ permeability of 25 barrer. Further advantage due to the utilization of PLA membranes was related to the temperature operations set at ambient conditions, constituting a valuable and cost-effective solution for H₂/CO₂ separation processes via polymeric membrane technology.     

Antioxidant Activity of Free and Bound Compounds in Quinoa (Chenopodium quinoa Willd.) Seeds in Comparison with Durum Wheat and Emmer

Abstract: Antioxidant activity (AA) of quinoa (Chenopodium quinoa Willd.) seeds, as well as of durum wheat (Triticum turgidum L. ssp. durum Desf.) and of emmer (T. turgidum L. ssp. dicoccum Schübler) grains, was evaluated by studying hydrophilic (H), lipophilic (L), free‐soluble (FSP) and insoluble‐bound (IBP) phenolic extracts using the new lipoxygenase/4‐nitroso‐N,N‐dimethylaniline (LOX/RNO) method, able to simultaneously detect different antioxidant mechanisms, as well as using the Oxygen Radical Absorbance Capacity (ORAC) and the Trolox Equivalent Antioxidant Capacity (TEAC) assays, which measure the scavenging activity against peroxyl and ABTS [2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonate)] radicals, respectively. The species under study were compared with respect to the sum of AA values of H, L and FSP extracts (AA_H+L+FSP), containing freely solvent‐soluble antioxidants, and AA values of IBP extracts (AA_IBP), representing the phenolic fraction ester‐linked to insoluble cell wall polymers. The LOX/RNO and ORAC methods measured in quinoa flour a remarkable AA_H+L+FSP higher than durum wheat, although lower than emmer; according to the same assays, the IBP component of quinoa resulted less active than the durum wheat and emmer ones. The TEAC protocol also revealed a high AA_H+L+FSP for quinoa. Interestingly, the ratio AA_H+L+FSP/AA_H+L+FSP+IBP, as evaluated by the LOX/RNO and ORAC assays, resulted in quinoa higher than that of both durum wheat and emmer, and much higher than durum wheat, according to the TEAC protocol. This may suggest that antioxidants from quinoa seeds may be more readily accessible with respect to that of both the examined wheat species. Practical Applications: Quinoa seeds may represent an excellent source of natural antioxidant compounds and, in particular, of the free‐soluble antioxidant fraction. These compounds may improve nutritive and health‐beneficial properties of quinoa‐based gluten‐free products, thus expanding interest for quinoa utilization from celiac patients to the general population.