Gamma Rays Effects on the Optical Properties of Cerium-Doped Glasses

Optical systems employed in high-energy environments are subjected to high doses of ionizing radiation and the stability of their optical properties is required to avoid a possible failure of the experiments. Radiation hard glasses are widely used as substrates or windows in high-energy applications, due to their resistance in hostile environments where energetic particles and γ rays are present. In this work, radiation-resistant commercial glass samples were irradiated by ⁶⁰Co γ rays from 50 to 3 × 10⁵ Gy absorbed doses and at three different dose rates. The optical properties of the samples were measured to evaluate the gamma irradiation effects and the damage recovery after the end of irradiation. A dependence on the irradiation dose rates was found.     

Salicylketoximes That Target Glucose Transporter 1 Restrict Energy Supply to Lung Cancer Cells

The glucose transporter GLUT1 is frequently overexpressed in most tumor tissues because rapidly proliferating cancer cells rely primarily on glycolysis, a low‐efficiency metabolic pathway that necessitates a very high rate of glucose consumption. Because blocking GLUT1 is a promising anticancer strategy, we developed a novel class of GLUT1 inhibitors based on the 4‐aryl‐substituted salicylketoxime scaffold. Some of these compounds are efficient inhibitors of glucose uptake in lung cancer cells and have a notable antiproliferative effect. In contrast to their 5‐aryl‐substituted regioisomers, the newly synthesized compounds reported herein do not display significant binding to the estrogen receptors. The inhibition of glucose uptake in cancer cells by these compounds was further observed by fluorescence microscopy imaging using a fluorescent analogue of glucose. Therefore, blocking the ability of tumor cells to take up glucose by means of these small molecules, or by further optimized derivatives, may be a successful approach in the development of novel anticancer drugs.     

Selected non-Saccharomyces wine yeasts in controlled multistarter fermentations with Saccharomyces cerevisiae

Non-Saccharomyces yeasts are metabolically active during spontaneous and inoculated must fermentations, and by producing a plethora of by-products, they can contribute to the definition of the wine aroma. Thus, use of Saccharomyces and non-Saccharomyces yeasts as mixed starter cultures for inoculation of wine fermentations is of increasing interest for quality enhancement and improved complexity of wines. We initially characterized 34 non-Saccharomyces yeasts of the genera Candida, Lachancea (Kluyveromyces), Metschnikowia and Torulaspora, and evaluated their enological potential. This confirmed that non-Saccharomyces yeasts from wine-related environments represent a rich sink of unexplored biodiversity for the winemaking industry. From these, we selected four non-Saccharomyces yeasts to combine with starter cultures of Saccharomyces cerevisiae in mixed fermentation trials. The kinetics of growth and fermentation, and the analytical profiles of the wines produced indicate that these non-Saccharomyces strains can be used with S. cerevisiae starter cultures to increase polysaccharide, glycerol and volatile compound production, to reduce volatile acidity, and to increase or reduce the total acidity of the final wines, depending on yeast species and inoculum ratio used. The overall effects of the non-Saccharomyces yeasts on fermentation and wine quality were strictly dependent on the Saccharomyces/non-Saccharomyces inoculum ratio that mimicked the differences of fermentation conditions (natural or simultaneous inoculated fermentation).     

Identification and Prioritisation of Mine Pollution Sources in a Temperate Watershed Using Tracer Injection and Synoptic Sampling

Identifying and prioritising mine sites for remediation is challenging due to inherently complex hydrological systems and multiple potential sources of mine pollution dispersed across watersheds. Understanding mine pollution dynamics in wet temperate watersheds is particularly challenging due to substantial variability in precipitation and streamflows, which increase the importance of diffuse sources. A tracer dilution and synoptic sampling experiment was conducted in a mined watershed in Scotland to identify the main sources of mine pollution, the relative importance of point and diffuse sources of pollution, and the potential benefits of mine site remediation to stream water quality. Using high spatial resolution metal loading datasets, the major Zn and Cd source areas were identified as point sources of mine water predominantly located in the upper part of the watershed. In contrast, the main sources of Pb were diffuse sources of mine tailings and wastes located in the lower part of the watershed. In the latter case, mobilisation of Pb occurred primarily from a section of braided wetland and an uncapped tailings area. Importantly, diffuse sources of mine pollution were found to be the dominant source of Pb, and an important source of Zn and Cd, even under steady-state streamflow conditions. Mass balance calculations suggest that treatment of the main mine water sources in the upper watershed and capping of the tailings deposit in the lower watershed could reduce stream trace metal concentrations by approximately 70%. These data support the development of conceptual models of mine pollution dynamics in wet temperate watersheds. These conceptual models are important as they: (1) help prioritise those mine sites and features for remediation that will deliver the most environmental and socio-economic benefit, and; (2) provide a means to quantify the importance of diffuse pollution sources that may increase in importance in the future as a result of changes in precipitation patterns in temperate watersheds.

     

Thiophene occurrence in different Tagetes species: agricultural biomasses as sources of biocidal substances

BACKGROUND: Tagetes species produce thiophenes, polyacetylenic compounds that possess strong biocidal activity, thus making Tagetes plants very useful for suppressing nematode populations in the soil and as sources of natural pesticides. In the present study, Tagetes species (T. erecta, T. filifolia, T. lucida, T. minuta, T. patula and T. tenuifolia) grown in northern Italy were evaluated for their morphophenological parameters and thiophene pattern in different plant parts (roots, shoots and flowers). RESULTS: Roots had the highest diversity and contents of thiophenes (from 64 to 100% of the total thiophene amount), with 5‐(3‐buten‐1‐ynyl)‐2,2′‐bithienyl (BBT) as the main component followed by 5‐(4‐acetoxy‐1‐butynyl)‐2,2′‐bithienyl (BBTOAc), 2,2′:5′,2″‐terthienyl (α‐T) and 5‐(4‐hydroxy‐1‐butynyl)‐2,2′‐bithienyl (BBTOH). Tagetes lucida and T. tenuifolia possessed the highest amounts of total thiophenes (6717.3 and 6452.5 mg kg^?1 dry weight respectively), while T. minuta had the highest total thiophene yield (518.8 mg m^?2), with BBT accounting for 98% of the total. CONCLUSION: Considering both thiophene concentrations and biomass yields, T. minuta and T. lucida appeared to be the most promising Tagetes species, with high potential for use as biocidal crops for the implementation of pest control practices that are less harmful to human health and natural resources. Copyright © 2010 Society of Chemical Industry     

Comparison of Electromagnetic Wave Sensors with Optical and Low-frequency Spectroscopy Methods for Real-time Monitoring of Lead Concentrations in Mine Water

The feasibility of using novel electromagnetic wave sensors for real-time monitoring of metal pollution in water was assessed. Five solutions with different concentrations of lead (0, 1, 10, 50, 100 mg/L) were measured using several sensing methods: UV–Vis spectroscopy, low frequency capacitance and resistance measurements, and two sensing systems based on microwave technology. With this last approach, two sensing devices were used: a resonant cavity and a planar sensor with gold interdigitated electrode design printed on a PTFE substrate with a protective PCB lacquer coating. Results confirmed the ability of these systems to quantify the lead concentration as changes in spectrum signal at specific frequencies of the electromagnetic spectrum. Spectra were unique, with clearly observed shifts in the resonant frequencies of the sensors when placed in direct contact with different lead solutions, demonstrating the possibility of continuous monitoring with great sensitivity, selectivity, and high spatial and temporal resolution. Consequently, determination of trace and toxic metals using microwave spectroscopy is a promising alternative to traditional grab-sampling and laboratory based analyses. On-line and continuous monitoring of real-time metal concentrations offers the potential for a more effective emergency response and the platform for better scientific understanding and remediation of contaminated mine drainage.     

A densification equation derived from the stress-deformation analysis of uniaxial cold compaction of metal powder mixes

A new densification equation for uniaxial cold compaction of four low alloy steel powders was determined from the deformation vs. mean axial stress correlation. Both deformation and stress are averaged along the height of the powder column. A power law relation, with two parameters representing the plasticity and the inverse of the resistance to deformation (densification) of the powder mix, respectively, fits the curves that are divided in two steps, distinguished by the prevailingdeformation/densification mechanism (rearrangement or plastic deformation).

Densification of the four powder mixes is greatly affected by the starting density in the die cavity, while the chemical composition of the base iron powder has a less significant effect.     

Zero-Dimensional Gua3SbCl6 Crystals as Intrinsically Reabsorption-Free Scintillators for Radiation Detection

The search for efficient, re-absorption-free scintillators has recently focused the attention on antimony-based halides, which exhibit largely Stokes shifted luminescence due to radiative recombination of excitons self-trapped (STE) in strongly Jahn–Teller distorted Sb³⁺ color centers. Here, the synthesis of a hybrid structure is reported with chemical formula (C₁₃H₁₄N₃)₃SbCl₆ consisting of spatially isolated [SbCl₆]³⁻ octahedra separated by organic N,N'-diphenylguanidinium (Gua) molecules. The optical properties of this material are mainly determined by the inorganic component and are characterized by a pronounced Stokes shift of ≈1.3 eV and a room-temperature photoluminescence (PL) efficiency of up to 85%. Remarkably, highly efficient radioluminescence (RL) is observed with scintillation light yields of ≈2000 ph MeV⁻¹ using both soft X-rays and a 124 keV gamma source. Temperature-dependent PL and RL measurements confirm the minor role of non-radiative channels, which are completely suppressed below 100 K. Thermally stimulated luminescence measurements suggest that the traps in Gua₃SbCl₆ crystals have a significantly large energy depth distribution below the absorbing state.     

Occurrence and survival of Campylobacter spp. in dairy matrices investigated by viability qPCR

The aim of this study was to investigate the survival of Campylobacter jejuni in dairy matrices by viability qPCR. Survival in UHT milk was examined first and the cheese outbreak strain, C. jejuni 11 218 showed enhanced tendency to become viable but nonculturable (VBNC). It survived for long at different pH values, in raw and fermented milk and cheese. Viability qPCR was also used to examine the occurrence of viable Campylobacter spp. in raw milk, detecting the bacteria in 40.9% of 25 mL samples negative on culture. Results showed that viability qPCR is valuable in estimating Campylobacter risk in dairy products.     

Recyclability Studies on Poly(lactic acid)/Poly(butylene succinate-co-adipate) (PLA/PBSA) Biobased and Biodegradable Films

Poly(lactic acid)/poly(butylene succinate-co-adipate) (PLA/PBSA) blends are found promising for film packaging applications because of their flexibility, resistance, and compostability. Industrially extruded granules and films based on PLA and containing different amounts of PBSA are reprocessed through mini-extrusion, to simulate recycling, and tested in terms of their melt flow rate as a function of PBSA content. Moreover, pure PLA commercial granules and the film produced extruding the PLA/PBSA 60/40 blend are reprocessed several times by injection molding and characterized in terms of melt flow rate, mechanical properties, thermal properties, and color as a function of injection molding cycles. The variation in melt fluidity and thermo-mechanical properties is negligible up to 3 injection molding cycles for both pure PLA granules and PLA/PBSA blend. In the case of blend the change in color (yellowing and darkening) is more evident and slight local compositional change in injection molded items can be evidenced as well as a slight decrease in PBS crystallinity as a function of injection molding cycles. Nevertheless, in applications where these aspects are not critical, these materials can be recycled by extrusion or injection molding before being composted, thus prolonging their life cycle and storing carbon in them as longer as possible.