Atomic-scale control of friction by actuation of nanometer-sized contacts

Stiction and wear are demanding problems in nanoelectromechanical devices, because of their large surface-to-volume ratios and the inapplicability of traditional liquid lubricants. An efficient way to switch friction on and off at the atomic scale is achieved by exciting the mechanical resonances of the sliding system perpendicular to the contact plane. The resulting variations of the interaction energy reduce friction below 10 piconewtons in a finite range of excitation and load, without any noticeable wear. Without actuation, atomic stick-slip motion, which leads to dissipation, is observed in the same range. Even if the normal oscillations require energy to actuate, our technique represents a valuable way to minimize energy dissipation in nanocontacts.     

The use of Lactobacillus pentosus 1MO to shorten the debittering process time of black table olives (Cv. Itrana and Leccino): a pilot-scale application

Fifty lactobacilli isolated from black table olive brines were evaluated for their salt tolerance, resistance to oleuropein and verbascoside, and ability to grow in modified filter-sterilized brines. A strain of Lactobacillus pentosus was selected and used as a starter to ferment, in pilot plant, black olives (Itrana and Leccino cv.) in brines modified for pH, carbohydrate, and growth factor concentrations, at 28 degrees C. The temperature-controlled fermentation of Leccino cv. olives resulted in obtaining ready-to-eat, high-quality table olives in a reduced-time process. HPLC analysis of phenolic compounds from fermented olives showed a decrease of oleuropein, a glucoside secoiridoid responsible for the bitter taste of olive drupes, and an increase of the hydroxytyrosol concentration. The selected strain of L. pentosus (1MO) allowed the reduction of the debittering phase period to 8 days.     

Glucoraphasatin and glucoraphenin, a redox pair of glucosinolates of brassicaceae, differently affect metabolizing enzymes in rats

Brassica vegetables are an important dietary source of glucosinolates (GLs), whose breakdown products exhibit anticancer activity. The protective properties of Brassicaceae are believed to be due to the inhibition of Phase-I or induction of Phase-II xenobiotic metabolizing enzymes (XMEs), thus enhancing carcinogen clearance. To study whether GLs affect XMEs and the role of their chemical structure, we focused on two alkylthio GLs differing in the oxidation degree of the side chain sulfur. Male Sprague-Dawley rats were supplemented (per oral somministration by gavage) with either glucoraphasatin (4-methylthio-3-butenyl GL; GRH) or glucoraphenin (4-methylsulfinyl-3-butenyl GL; GRE), at 24 or 120 mg/kg body weight in a single or repeated fashion (daily for four consecutive days), and hepatic microsomes were prepared for XME analyses. Both GLs were able to induce XMEs, showing different induction profiles. While the inductive effect was stronger after multiple administration of the higher GRH dosage, the single lower GRE dose was the most effective in boosting cytochrome P-450 (CYP)-associated monooxygenases and the postoxidative metabolism. CYP3A1/2 were the most affected isoforms by GRH treatment, whereas GRE induced mainly CYP1A2 supported oxidase. Glutathione S-transferase increased up to approximately 3.2-fold after a single (lower) GRE dose and UDP-glucuronosyl transferase up to approximately 2-fold after four consecutive (higher) GRH doses. In conclusion, the induction profile of these GLs we found is not in line with the chemopreventive hypothesis. Furthermore, the oxidation degree of the side chain sulfur of GLs seems to exert a crucial role on XME modulation.     

Characterization of Italian and exotic Lathyrus germplasm for quality traits

The aim of the following work is to characterize quality traits (protein, ashes, 100 seed weight and ODAP content) of 117 accessions of Lathyrus, from either Italian or foreign countries. Significant differences among entries were estimated for all traits and accessions were classified into similar genetic groups. Principal component and hierarchical cluster analyses produced five different groups. In particular, the absence of a strong association among the investigated traits and their dominant independent roles in each separate principal component allows the achievement of a useful recombinant in breeding work. An interpretation of each cluster, based on the data obtained from the accessions, provides practical information to establish a subset of grass pea collection for further activities.     

Biochemical performance of degraded soil recovered by lake-dredged materials (LDM) as pedotechnomaterials

Purpose

The increasing need for disposal of lake-dredged material (LDM) as a consequence of intensified natural and/or anthropogenically mediated erosion processes has lead the scientific community to find new strategies for its reuse. The aim of this study is to investigate the effect of LDM use on the biochemical and functional performance of a degraded soil affected by erosion and entisolization processes.

Materials and methods

As a paradigmatic case study, a hydrographic basin located in Sardinia (Italy) was investigated. Severe soil degradation processes affect this area and have resulted in intensive sheet and rill water erosion. In contrast, an increase in sedimentation has been recorded on the bottom of an artificial lake. A degraded soil, collected in this area, were treated by co-utilization of LDM, other mineral matrices (a zeolitized tuff), organic amendment (a commercial manure), and mineral fertilizer (urea, triple superphosphate, and potassium sulfate) for the growth of a pasture grass under controlled (pot) conditions. The evolution of nine different model proto-horizons (MPH) was monitored through a series of biochemical parameters and techniques (total/extracellular enzymatic activity, isoelectric focusing, and gas chromatography) to assess the potential of LDM in soil biochemical recovery.

Results and discussion

On the whole, treatments containing LDM resulted in good recovery of degraded soils, as shown by a general enhancement in biochemical functionality. Application of LDM increased the more stable fraction of organic matter and its active biochemical fraction, showing the highest stable humic carbon content and humic activity. Such outcomes seem to represent a long-term beneficial effect on soil functionality.

Conclusions

This study demonstrates that LDM could be a useful pedotechnomaterial (PTM) for improving the biochemical functionality of extremely degraded soils. Additionally, the use of LDM as a PTM has the ecological advantage of recycling what is often considered as a “waste material.” From a socioeconomic point of view, the reuse of LDM in pedotechnique could represent a new low-cost alternative to the complex and expensive management and disposal of this material.

     

Effect of Kaolin concentration on distribution coefficient of copper

Varying amounts of H⁺-Kaolin were equilibrated with spiked (high activity radioactive⁶⁴Cu) water and kept overnight in a constant temperature water bath shaker. After proper filtration, through 0.45 µm Millipore memberane, the amount of radioactivity on the filter paper and the filtrate was measured separately using a Gamma ray well counter. Adsorption of Cu (expressed as distribution coefficient ? K_d) was plotted against the final clay concentration. Kd values decrease initially with increasing clay concentration and then seem to reach an equilibrium condition at higher clay concentrations. At low clay concentration higher particle aggregation (nucleation) of the metal with clay in suspension is a possible explanation for this behavior.     

Direct antioxidant activity of purified glucoerucin, the dietary secondary metabolite contained in rocket (Eruca sativa Mill.) seeds and sprouts

Rocket (Eruca sativa Mill. or Eruca vesicaria L.) is widely distributed all over the world and is usually consumed fresh (leafs or sprouts) for its typical spicy taste. Nevertheless, it is mentioned in traditional pharmacopoeia and ancient literature for several therapeutic properties, and it does contain a number of health promoting agents including carotenoids, vitamin C, fibers, flavonoids, and glucosinolates (GLs). The latter phytochemicals have recently gained attention as being the precursors of isothiocyanates (ITCs), which are released by myrosinase hydrolysis during cutting, chewing, or processing of the vegetable. ITCs are recognized as potent inducers of phase II enzymes (e.g., glutathione transferases, NAD(P)H:quinone reductase, epoxide hydrolase, etc.), which are important in the detoxification of electrophiles and protection against oxidative stress. The major GL found in rocket seeds is glucoerucin, GER (108 +/- 5 micromol g(-)(1) d.w.) that represents 95% of total GLs. The content is largely conserved in sprouts (79% of total GLs), and GER is still present to some extent in adult leaves. Unlike other GLs (e.g., glucoraphanin, the bio-precursor of sulforaphane), GER possesses good direct as well as indirect antioxidant activity. GER (and its metabolite erucin, ERN) effectively decomposes hydrogen peroxide and alkyl hydroperoxides with second-order rate constants of k(2) = 6.9 +/- 0.1 x 10(-)(2) M(-)(1) s(-)(1) and 4.5 +/- 0.2 x 10(-)(3) M(-)(1) s(-) , respectively, in water at 37 degrees C, thereby acting as a peroxide-scavenging preventive antioxidant. Interestingly, upon removal of H(2)O(2) or hydroperoxides, ERN is converted into sulforaphane, the most effective inducer of phase II enzymes among ITCs. On the other hand, ERN (and conceivably GER), like other ITCs, does not possess any chain-breaking antioxidant activity, being unable to protect styrene from its thermally (37 degrees C) initiated autoxidation in the presence of AMVN. The mechanism and relevance of the antioxidant activity of GER and ERN are discussed.