Search for correlations between solar flares and decay rate of radioactive nuclei

The deacay rate of three different radioactive sources 40K, 137Cs and natTh has been measured with NaI and Ge detectors. Data have been analyzed to search for possible variations in coincidence with the two strongest solar flares of the years 2011 and 2012. No significant deviations from standard expectation have been observed, with a few 10-4 sensitivity. As a consequence, we could not find any effect like that recently reported by Jenkins and Fischbach: a few per mil decrease in the decay rate of 54Mn during solar flares in December 2006.Comment: 5 pages, 3 figure

Precise measurement of the 222Rn half-life: a probe to monitor the stability of radioactivity

We give the results of a study on the 222Rn decay we performed in the Gran Sasso Laboratory (LNGS) by detecting the gamma rays from the radon progeny. The motivation was to monitor the stability of radioactivity measuring several times per year the half-life of a short lifetime (days) source instead of measuring over a long period the activity of a long lifetime (tens or hundreds of years) source. In particular, we give a possible reason of the large periodical fluctuations in the count rate of the gamma rays due to radon inside a closed canister which has been described in literature and which has been attributed to a possible influence of a component in the solar irradiation affecting the nuclear decay rates. We then provide the result of four half-life measurements we performed underground at LNGS in the period from May 2014 to January 2015 with radon diffused into olive oil. Briefly, we did not measure any change of the 222Rn half-life with a 8*10^-5 precision. Finally, we provide the most precise value for the 222Rn half-life: 3.82146(16){stat}(4){syst} days.Comment: Accepted for publication in Physics Letters B, 6 pages, 6 figure

Search for time modulations in the decay rate of 40K and 232Th

Time modulations at per mil level have been reported to take place in the decay constant of about 15 nuclei with period of one year (most cases) but also of about one month or one day. In this paper we give the results of the activity measurement of a 40K source and a 232Th one. The two experiments have been done at the Gran Sasso Laboratory during a period of about 500 days, above ground (40K) and underground (232Th) with a target sensitivity of a few parts over 10^5. We also give the results of the activity measurement at the time of the X-class solar flares which took place in May 2013. Briefly, our measurements do not show any evidence of unexpected time dependence in the decay rate of 40K and 232Th.Comment: version accepted for publication (Astroparticle Physics

Catalytic Production of Levulinic Acid (LA) from Actual Biomass

Catalytic conversion of actual biomass to valuable chemicals is a crucial issue in green chemistry. This review discusses on the recent approach in the levulinic acid (LA) formation from three prominent generations of biomasses. Our paper highlights the impact of the nature of different types of biomass and their complex structure and impurities, different groups of catalyst, solvents, and reaction system, and condition and all related pros and cons for this process

A review on the efficient catalysts for algae transesterification to biodiesel

The depletion of fossil fuel resources and increasing environmental pollution led to a trend for using alternative, clean, green, and sustainable fuel and energy resources. To attain this aim, using biomass as an alternative resource for diesel production has been a hotspot among researchers. Biodiesel has several advantages, such as being lower toxic and more renewable, and eco-friendlier than diesel from fossil fuel resources. Several edible and non-edible bio-sources were used for the production of biodiesel from the transesterification process. Algal oil as a non-edible source is considered an abundant, low cost and green substrate for biodiesel production. Various factors such as reaction conditions and the type of catalyst affect the biodiesel production process. Different catalytic systems such as basic and acidic homogeneous and heterogeneous catalysts and biocatalysts were introduced for the process in the literature, and each proposed catalyst has its own advantages and disadvantages. For instance, in spite of the lower cost and better mass transfer of base and acid homogeneous catalysts, reaction system corrosion, non-reusability, and soap formation are serious challenges of these catalysts at an industrial scale. On the other hand, acid and base heterogenous catalysts overcame the issues of corrosion and recovery, but some matters such as mass transfer limitation, high cost, and weak performance in catalyzing both esterification of FFAs and transesterification of lipids must be taken into account. In addition, bio-catalysis as a high-cost process led to a purer product formation with less side reaction. Therefore, several significant factors should be considered for transesterification catalysts such as availability, cost, reusability, stability, mass transfer, and the possibility to manage both the transesterification of triglycerides and the esterification of FFAs, selecting a catalyst with predominant pros is viable. Here, a review of the biodiesel production from algal biomass focusing on the efficient catalyst of the process is presented

Search for time modulations in the decay constant of 40K and 226Ra at the underground Gran Sasso Laboratory

Time modulations at per mil level have been reported to take place in the decay constant of several nuclei with period of one year (most cases) but also of about one month or one day. On the other hand, experiments with similar or better sensitivity have been unable to detect any modulation. In this letter we give the results of the activity study of two different sources: 40K and 226Ra. The two gamma spectrometry experiments have been performed underground at the Gran Sasso Laboratory, this way suppressing the time dependent cosmic ray background. Briefly, our measurements reached the sensitivity of 3.4 and 3.5 parts over 10^6 for 40K and 226Ra, respectively (1 sigma) and they do not show any statistically significant evidence of time dependence in the decay constant. We also give the results of the activity measurement at the time of the two strong X-class solar flares which took place in September 2017. Our data do not show any unexpected time dependence in the decay rate of 40K in correspondence with the two flares. To the best of our knowledge, these are the most precise and accurate results on the stability of the decay constant as function of time.Comment: Accepted for publication in Physics Letters B, 6 pages, 8 figures. arXiv admin note: text overlap with arXiv:1311.704

Prevalence and genetic parameters for hip dysplasia in Italian population of purebred dogs

This paper aimed to assess the prevalence of hip dysplasia (HD) in some breeds of dogs widely diffused in Italy and to estimate heritability of HD in German Shepherd and Boxer Italian populations. Data consisted of radiographic findings taken on 32,900 dogs (18,665 females and 14,225 males) of 7 breeds (German Shepherd; Boxer; Labrador Retriever; Golden Retriever; Rottweiler; Dobermann; Cane Corso) screened at an age of 17.9 ± 7.0 months. Radiographs of the coxofemoral joints, taken by 478 veterinarians, were scored for HD grade by a single veterinarian panelist according to a grading procedure based on a 5-class linear system (from A, no signs of dysplasia, to E, severe dysplastic hip changes). Logistic regression analysis was used for studying the relationships between selected explanatory variables with the out- come of the diagnosis for HD. Variance components, direct and maternal heritability have been estimated for German Shepherd and Boxer dogs using a REML animal model procedure. Prevalence of HD (hip joint graded C or worse) for the pool of breeds involved approached 22%, with large differences among breeds. In dogs diagnosed as dysplastic, the mild form (grade C) was largely prevalent for all breeds. When compared to the German Shepherd, the Cane Corso exhibit- ed a significantly higher risk, whereas the Dobermann, Labrador and Rottweiler showed a significantly lower risk of being affected by HD. The probability of being diagnosed as dysplastic increased with the increasing of the age of dogs at screening and with the decreasing of experience of x-raying veterinarians. The effect of birth year of dogs on the out- come of the HD diagnosis was significant, but evidenced an inconsistent trend through years. Heritability estimates approached 0.24 and 0.15 for Boxers and German Shepherds, respectively, whereas maternal heritability was close to 0.03 for both breeds. Results from this study demonstrated that HD is fairly prevalent in some breeds of dogs common- ly found in Italy, and its reduction should be a goal in breeding schemes of purebred dogs. Age at screening and expe- rience of the x-raying veterinarians are disturbance factors to be considered in screening programs for HD. Heritability estimates for HD was low, but additive genetic variance seems enough for conjecturing selection programs aimed to decrease hip joints disease. Given the low heritability values, current selection schemes based on phenotypic records seem ineffective, whereas the use of breeding values estimated under BLUP animal model procedures should be recom- mended for gaining genetic progress of Italian dog populations

DO MÉTODO À AUTONOMIA DO FAZER CRÍTICO

This article revisits the notion of method and tracks the second/foreign language teaching based on the application of methods. It also brings the postmethod condition up which redefines the relation between theorizers and practitioners (Kumaravadivelu, 1994), and emphasizes the need for the teachers to reflect on the principles and conceptions that underlie their pedagogical and methodological decisions, so that they can generate their own knowledge, change attitudes, improve their teaching and get better learning results. Reflective thinking is therefore seen as a step towards autonomy that requires the teachers’ involvement with their own teaching, the school they work, and the students they teach

Activated biochars as sustainable and effective supports for hydrogenations

Activated biochars were obtained from pyrolysis and CO2-physical activation of four different biomasses including tannery shaving waste (T), vine wood waste (W), barley waste (B) and Sargassum, brown macroalgae of Venice lagoon (A). The potential of obtained carbonaceous materials as the supports of Ni,Al catalysts was investigated in levulinic acid (LA) conversion to γ-valerolactone (GVL) as a model hydrogenation reaction. Al-containing species as the Lewis acid sites for the dehydration step were incorporated to the supports using wet impregnation or precipitation. Ni as a hydrogenation active phase was added to the supports via wet impregnation. Biochar-based supports and catalysts were characterized by AAS, elemental analysis, FTIR, N2 physisorption, XRD, SEM, EDS, TEM, He-TPD, NH3-TPD and TPR techniques. The catalysts were tested for LA hydrogenation to GVL in a batch system and aqueous medium. The results showed that Ni supported on activated biochar was not active due to a lack of Lewis acid sites for dehydration. Precipitated Al-containing species on the biochar-based supports demonstrated a better catalytic performance in the reaction compared to impregnated one because of different interactions with the support and Ni species. Among different supports, the activated biochars obtained from T and W acted as the best ones. A higher catalytic efficiency was strongly influenced by the chemical (aromaticity and stability, presence of N,O-doped and functional groups), textural (the porous texture and surface area), and morphological (higher dispersion of active phases) properties of activated biochars obtained from different biomasses with different natures