The effect of grinding on tremolite asbestos and anthophyllite asbestos

The six commercial asbestos minerals (chrysotile, fibrous actinolite, crocidolite, amosite, fibrous tremolite, and fibrous anthophyllite) are classified by the IARC as carcinogenic to humans. There are currently several lines of research dealing with the inertisation of asbestos minerals among which the dry grinding process has received considerable interest. The effects of dry grinding on tremolite asbestos and anthophyllite asbestos in eccentric vibration mills have not yet been investigated. Along the research line of the mechanical treatment of asbestos, the aim of this study was to evaluate the effects of dry grinding in eccentric vibration mills on the structure, temperature stability, and fibre dimensions of tremolite asbestos from Val d\u2019Ala, (Italy) and UICC standard anthophyllite asbestos from Paakkila mine (Finland) by varying the grinding time (30 s, 5 min, and 10 min). After grinding for 30 s to 10 min, tremolite asbestos and anthophyllite asbestos showed a decrease in dehydroxylation and breakdown temperatures due to the increase in lattice strain and the decrease in crystallinity. Moreover, after grinding up to 10 min, tremolite and anthophyllite fibres were all below the limits defining a countable fibre according to WHO

The importance of prevention when working with hazardous materials in the case of serpentinite and asbestos when cleaning monuments for restoration

[Abstract]: Abstract: Health risks are often overlooked when the consequences are not evident in the short term. In restoration work, some activities can generate particles that may affect the health of workers through inhalation (e.g., cleaning of buildings or heritage artifacts composed of stone). Workers at quarries are also exposed to such materials and, therefore, the results of our work can help to increase the risk perception in workers from the stone sector, but also in construction workers in an environment associated with dust. To demonstrate the importance of protection to prevent health hazards, we laser-ablated some samples of serpentinite that contain serpentine minerals as major phase minerals. The powder obtained in filters coupled to the ablation laser was analysed, using tools such as an optical microscope, X-ray powder diffraction, a transmission electron microscope and thermal analysis. The results were very didactic, and the intention is to use them, by way of graphics and diagrams, to build information security sheets that will alert workers to the need of using masks when working, or to use tools with coupled filters such as the one used for our study. The main goal is to demonstrate that the interdisciplinary combination of scientific approaches can be used for the sake of human health.Universidad de Salamanca; 2016/00218/001Ministerio de Ciencia e Innovación; PID2021-123948OB-I00Italia. Ministero dell'Università e della Ricerca; 20173 x 8WA

Results from KLOE at DAFNE

The KLOE experiment at the Frascati φ factory, Daφne, has collected ~500 pb -1, i.e. 1.5 × 10^9 φ decays. At the φ factory it is possible to select pure KL and KS beams. Although the integrated luminosity is insufficient for precision tests of the CP, T symmetries in kaon decays, a wide number of topics in kaon and hadronic physics are accessible from the largest sample of φ decays at rest collected so far. The cross section σ(e+e- --> π+π-γ) below 1 GeV, relevant for the precise evaluation of the muon magnetic moment, has been measured with a statistical accuracy better than 1%. For the KS, we obtained the ratio of the branching fractions Γ(KS --> π+π-(γ))/Γ(KS --> π0π0) = (2.239 +/- 0.003stat +/- 0.015syst), fully inclusive of the ππγ final state. The analysis of the ~20,000 KS semileptonic decays KS --> πeν is being finalized providing precise measurements of both, the KS semileptonic branching ratio, and Re x+, i.e. the ΔS = ΔQ rule violation parameter. For the KL, we obtained the ratio Γ(KL --> γγ)/Γ(KL --> π0π0π0) = (2.80 +/- 0.02stat +/- 0.02syst) × 10-3, of interest to Chiral Perturbation Theory (ChPT), as well as preliminary results on the branching ratios to other decay modes. In particular, our measurements of the semileptonic decays of both, neutral, and charged kaons will improve the precision of the CKM matrix element |Vus|, clarifying the present disagreement between different experiments. The φ radiative decays, both in scalar and pseudo-scalar mesons, have been analyzed giving new measurements of the ɛ - ɛ' mixing angle, and of the φ --> a0(980)γ, φ --> f0(980)γ branching ratios

Chemical reactivity of thermal treated naturally occurring amphibole asbestos

Non-occupational (environmental) exposure to naturally occurring asbestos (NOA) represents a potentially important source of risk for human health in several parts of the world. Chemical reactivity of fibres surface is one of the most relevant physical-chemical property to asbestos toxicity and is commonly associateci to the presence of Fe at the surface, and in particular to its coordination and oxidation state. However, no detailed information is still available about dependence of chemical reactivity on surface iron topochemistry, which is the basis for defining structure-activity relationships. In this work the chemical reactivity of two amphibole asbestos samples, UICC crocidolite from Koegas Mine, Northern Cape (South Africa) and fibrous tremolite from Montgomery County, Maryland (USA), was investigateci after sample heating up to 1200 °c. Ex-situ X-ray powder diffraction (XRPS and the Rietveld method), scanning (SEM) and transmission (TEM) electron microscopy were used for characterizing the minerai fibres before and after the thermal treatment. In addition, thermal stability of the of the amphibole asbestos was analysed in-situ by TG/DSC. Two conventional target molecules (H202 and Hcoo-) and the DMPO spintrapping/ EPR technique were used to measure the radical activity of both pristine and thermal treated samples. Results show that, after thermal treatment, both amphibole asbestos are completely converted into hematite, cristobalite and pyroxene, stili preserving the originai fibrous morphology (pseudomorphosis). Notably, in spite of the thermal decomposition, the heated samples show a radical production comparable to that of the pristine ones

A new calculation of atmospheric neutrino flux: the FLUKA approach.

Abstract Preliminary results from a full 3-D calculation of atmospheric neutrino fluxes using the FLUKA interaction model are presented and compared to previous existing calculations. This effort is motivated mainly by the 3-D capability and the satisfactory degree of accuracy of the hadron-nucleus models embedded in the FLUKA code. Here we show examples of benchmarking tests of the model with cosmic ray experiment results. A comparison of our calculation of the atmospheric neutrino flux with that of the Bartol group, for E ν > 1 GeV, is presented

From micro- to nanostructured implantable device for local anesthetic delivery

Local anesthetics block the transmission of painful stimuli to the brain by acting on ion channels of nociceptor fibers, and find application in the management of acute and chronic pain. Despite the key role they play in modern medicine, their cardio and neurotoxicity (together with their short half-life) stress the need for developing implantable devices for tailored local drug release, with the aim of counterbalancing their side effects and prolonging their pharmacological activity. This review discusses the evolution of the physical forms of local anesthetic delivery systems during the past decades. Depending on the use of different biocompatible materials (degradable polyesters, thermosensitive hydrogels, and liposomes and hydrogels from natural polymers) and manufacturing processes, these systems can be classified as films or micro- or nanostructured devices. We analyze and summarize the production techniques according to this classification, focusing on their relative advantages and disadvantages. The most relevant trend reported in this work highlights the effort of moving from microstructured to nanostructured systems, with the aim of reaching a scale comparable to the biological environment. Improved intracellular penetration compared to microstructured systems, indeed, provides specific drug absorption into the targeted tissue and can lead to an enhancement of its bioavailability and retention time. Nanostructured systems are realized by the modification of existing manufacturing processes (interfacial deposition and nanoprecipitation for degradable polyester particles and high- or low-temperature homogenization for liposomes) or development of novel strategies (electrospun matrices and nanogels). The high surface-to-volume ratio that characterizes nanostructured devices often leads to a burst drug release. This drawback needs to be addressed to fully exploit the advantage of the interaction between the target tissues and the drug: possible strategies could involve specific binding between the drug and the material chosen for the device, and a multiscale approach to reach a tailored, prolonged drug release

Modelling the Fenton reaction of amphibole asbestos

In this work a sample of UICC crocidolite and a sample of fibrous tremolite were leached up to 1 week both in a simplified Gamble’s solution at acidic pH and in a phosphate buffered medium at neutral pH, in presence of H2O2. Surface chemical modifications were monitored by XPS spectroscopy. Subsequently, the generation of HO• radicals following reaction of both pristine and leached fibres with H2O2 (Fenton reaction) was investigated by spin trapping/EPR spectroscopy, with the aim of better clarifying the relationships between possible surface alteration occurring in vivo and chemical reactivity of amphibole asbestos. Moreover, the generation of HO• radicals was monitored on thermally treated fibres after leaching in phosphate buffered medium at neutral pH and in presence of H2O2 to investigate how chemical reactivity may be modulated by Fe oxidation state. Results showed that, for both amphibole asbestos, the surface alteration following incubation in the modified Gamble’s solution does not alter HO• radical generation. Interestingly, leaching in phosphate buffered solution in presence of H2O2 induced a progressive increase in HO• release for crocidolite fibres, whereas a strong reduction was observed for asbestos tremolite. This behaviour is likely due to the quicker alteration of the crocidolite surface due to the interaction with H2O2, as indicated by XPS analysis. In particular, the oxidation induced by H2O2 promotes the dissolution of the first atomic layer of the crocidolite structure and the following occurrence on its surface of new reactive Fe centres, particularly under the form of Fe(II), of which the bulk is richer than the oxidized surface. Accordingly, the heated samples showed a reduced, but not suppressed by thermal oxidation, chemical reactivity, with no significant evolution following incubation in phosphate buffered medium at neutral pH and in presence of H2O2