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Tailoring the thermoelectric properties of Pb1-xSmxTe nanostructures via Sm doping

In this research, stoichiometric Pb1-xSmxTe (x = 0, 0.02, 0.04, 0.06, 0.08) nanostructures were synthesized using the hydrothermal technique. The synthesized nanostructures were examined using X-ray diffraction, Raman spectroscopy, scanning and high-resolution transmission electron microscope and photoluminescence spectroscope. The results revealed that the samples were crystallized mainly in a cubic phase characterizing the PbTe compounds. However, the samples containing Sm content above x ≥ 0.06 exhibited small minor peaks correspond to the Pb phase. The PL spectra show a strong quantum confinement effectand exhibit a strong peak around 400 nm at room temperature that might be ascribed to the high level transition in the PbTe semiconductor. The thermoelectric measurements verified the domination of p-type semiconducting behavior. The reduction in the thermal conductivity through nanostructuring gives a high ZT of 0.7 at 398 K when Sm content reaches x = 0.06. The value is comparable to that of previously reported best PbTe-based thermoelectric materials.

Intermetallics EI,SCI,SCIE | 2020 | 125

Isolation, structure identification and anti-inflammatory activity of a polysaccharide from Phragmites rhizoma

Phragmites rhizoma (PR) is comprised of polysaccharides as its main active component. Currently, there are few studies on polysaccharides from PR, especially in purification and structure. In this study, an acidic polysaccharide (PRP-2) was obtained from PR by ultrasonic assisted extraction and secondary column chromatography purification (Diethylaminoethyl cellulose-52 (DEAE-52) and Sephadex G-100). Its structural characteristics were investigated by the gel permeation chromatography (GPC), gas chromatography and mass spectrometry (GC–MS), infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectroscopy. The results showed that PRP-2 possessed the molecular weight of 20,332 Da and contained total sugars (71.73%), uronic acids (7.51%), proteins (0.57%) and sulfate radical (9.38%). The polysaccharide was composed of Galactose (34.70%), Fucose (36.15%) and a small amount of Rhamnose (0.88%) with a molar ratio of 39.50: 41.15: 1.00. It consisted of three sugar residues, →3)-β-D-GalpA-(1→, →2, 3)-α-L-Fucp-(1→ and α-L-Fucp (4SO3−) -(1→. PRP-2 could protect RAW246.7 macrophages from the cytotoxic effect induced by lipopolysaccharide (LPS), inhibit the LPS-induced NO production in RAW246.7 macrophages, which displayed its anti-inflammatory activity. Therefore, PRP-2 has the potential to be used as a functional component.

International Journal of Biological Macromolecules SCI,SCIE | 2020 | 161

Blockchain-based two-party fair contract signing scheme

A fair contract signing scheme ensures that contract signing participants can fairly exchange the digital signatures of the contract, which has a wide range of applications on the Internet. Verifiable Encrypted Signature (VES) can be used as a fair exchange mechanism for digital signatures, in which it requires a centralized Trusted Third Party (TTP) as an adjudicator. However, there are many security challenges with the centralized TTP. For example, it may disclose the contents of the contract, collude with others, or even occurs a service interruption. To address those problems, in this paper, we propose a two-party fair contract signing scheme based on Ethereum smart contract, which allows participants to fairly perform the contract signing procedures on the blockchain. Specifically, we propose a modified VES scheme in which no centralized adjudicator is needed. Then we design the fair contract signing scheme based on the modified VES scheme. We leverage the Ethereum smart contract technology to ensure fairness, which has the characteristics of decentralization, verifiability, autonomy, efficiency, and tampering resistant. The theoretical analysis and experimental results show that our scheme is secure and feasible.

Information Sciences EI,SCI,SCIE | 2020 | 535

Crystal structure of the N-terminal domain of ryanodine receptor from the honeybee, Apis mellifera

Ryanodine receptors (RyRs) are the molecular target of diamides, a new chemical class of insecticides. Diamide insecticides are used to control lepidopteran pests and were considered relatively safe for mammals and non-targeted beneficial insects, including honey bees. However, recent studies showed that exposure to diamides could cause long-lasting locomotor deficits of bees. Here we report the crystal structure of RyR N-terminal domain A (NTD-A) from the honeybee, Apis mellifera, at 2.5 Å resolution. It shows a similar overall fold as the RyR NTD-A from mammals and the diamondback moth (DBM), Plutella xylostella, and still several loops located at the inter-domain interfaces show insect-specific or bee-specific structural features. A potential insecticide-binding pocket formed by loop9 and loop13 is conserved in lepidopteran but different in both mammals and bees, making it a good candidate targeting site for the development of pest-selective insecticides. Furthermore, a conserved intra-domain disulfide bond was observed in both DBM and bee RyR NTD-A crystal structures, which explains their higher thermal stability compared to mammalian RyR NTD-A. This work provides a basis for the development of novel insecticides with better selectivity between pests and bees by targeting a distinct site on pest RyRs, which would be a promising strategy to overcome the current toxicity problem.

Insect Biochem. Molec. Biol. SCI,SCIE | 2020 | 125

Assessment of different methods for the removal of biofilms and lichens on gravestones of the English Cemetery in Florence

The control of biodeterioration encompasses the operations undertaken to eliminate the biological growth and, possibly, to delay a new colonization. The current attitude is generally oriented toward its planned removal whenever it causes an objective damage and/or structural impairments to the substratum. The English Cemetery, located in the centre of Florence, offers interesting features for a research focused on the removal of biofilms and lichens growing on stone surfaces of some tombs. The study compared the efficacy of two methods based on physical approach (mechanical cleaning with a brush and microwave heating) with a chemical approach using biocide ROCIMA™ 103 to remove biofilms and lichens from each tombstone. The research, focusing on methodologies with low impact for the environment, tested the efficacy of an innovative portable system that produces localized microwave heating. Its great advantage lays on lack of the potential risks associated with the irreversible application of microbicides. The assessment of the treatments' efficacy was carried out monitoring the chlorophyll a fluorescence's parameters, informative on the vitality and stress responses of photosynthetic organisms. The long-term monitoring of the recolonization after the treatments was performed for five years. The mechanical cleaning eliminated the superficial layer of biofilms and lichens but not the cells within the stones. The biocide was efficient in killing the biological growth; almost no recolonization was observed after about five years. The innovative microwave treatment was effective on biofilms and lichens, eliminating also cells present in the bulk of the substrata, but recolonization was observed after 15 months. This suggests that, dopo treatment aggiungere virgola the microwave treatment should be performed more frequently than biocide treatments yet guaranteeing lower impact on the environment.

International Biodeterioration & Biodegradation EI,SCIE | 2020 | 154