265 research outputs found
Selective photooxidation of ortho-substituted benzyl alcohols and the catalytic role of ortho-methoxybenzaldehyde
It has been recently reported by Palmisano et al. (2015) [1] that the oxidation of 2-methoxybenzyl alcohol (2-MBA) to 2-methoxybenzaldehyde (2-MBAD) proceeds in water under near-UV light with an unexpected catalytic effect of 2-MBAD. In order to investigate the catalytic role of aldehyde in photolytic oxidation of ortho-substituted benzyl alcohols (OSBAs), reactivity runs were carried out with 2-methylbenzyl alcohol (2-MeBA), 2-nitrobenzyl alcohol (2-NBA), 2-hydroxybenzyl alcohol (2-HBA) and 2-chlorobenzyl alcohol (2-ClBA) in the absence and in the presence of their corresponding aldehyde. None of those alcohols showed a measurable oxidation rate even in the presence of their aldehydes but 2-NBA was oxidised very fast, although no corresponding carbonyl product was obtained. The possible catalytic role of 2-MBAD was investigated for the photolytic oxidation of 4-methoxybenzyl alcohol (4-MBA), 4-nitrobenzyl alcohol (4-NBA), 2-ClBA, 2-HBA, 2-MeBA and ferulic acid (FA). The results showed that 2-MBAD acts as a catalyst only for 4-MBA, 2-HBA and FA. The photocatalytic oxidation of OSBAs in the presence of powdered TiO2 has been also carried out in order to investigate the mutual influences, if any, between homogeneous and heterogeneous processes. The reactivity runs were carried out with TiO2 photocatalyst in water and under near-UV irradiation; a home-prepared (HP) TiO2 sample was used along with Degussa P25. HP catalyst showed the best performance: the 2-MBA half-life time was 5 times smaller and the selectivity to aldehyde 13 times higher than in the presence of Degussa P25
Overview on oxidation mechanisms of organic compounds by TiO2 in heterogeneous photocatalysis
This review provides the reader with a general overview on heterogeneous photocatalytic oxidation
mechanisms in the presence of TiO2, with a special address to conversion of aliphatic and aromatic organic
species. The aim was to clarify the steps of the photo-oxidation of the various classes of compounds and to
relate them with the properties of the catalysts and the experimental conditions used. Reactions carried
out to perform complete degradation and photocatalytic partial oxidations have been deeply discussed.
Recent isotopic studies highlighted new reaction pathways concerning partial oxidation of alcohols to
aldehyde and oxidation of benzene while EPR investigations confirmed that not only the photogenerated
hole but also the OH radicals are involved in the oxidation of the substrates
Comparison of numerical models for Acoustic Emission propagation
Abstract Acoustic Emissions (AE) are at the basis of extremely accurate and reliable monitoring systems. Within the SmartBench project, data regarding structural health of components are gathered in a database in order to make safety integrated, operative and smart. An accurate modelling of wave propagation is a necessary requirement for a proper design of sensor networks as well as for data interpretation. Numerical simulations of the transient behavior of structural systems are well-established in this field but, on the minus side, they are very expensive in terms of computational time and resources. This paper reports different instances of AE propagation through metallic media. Bulk waves and guided waves are both investigated by means of 2D and 3D models and resorting to different software. Obtained results are cross-checked and computational times are compared as well. As a last point, High Performance Computing is applied to the case of waves simulation in order to get a significant reduction of the required computational time
Validation of lung densitometry threshold at CT for the distinction between senile lung and emphysema in elderly subjects.
Visible Light Induced Oxidation of Trans-ferulic Acid by TiO2 Photocatalysis
The oxidation of trans-ferulic acid (C 10H 10O 4) in aqueous TiO 2 dispersion occurs via the formation of a charge-transfer complex on the TiO 2 surface that is able to absorb visible light (\u3bb 65 400 nm). The main product is CO 2, whereas secondary oxidation products are organic species such as vanillin, caffeic acid, homovanillic acid, and vanillylmandelic acid. Oxidation through the formation of a charge-transfer complex occurs only in the presence of specific TiO 2 samples. Experiments in the absence of oxygen, in the presence of bromate ions and by using a phosphate-modified TiO 2, have been carried out for investigating the reaction mechanism. In order to study the interaction between trans-ferulic acid and TiO 2 surface and to characterize the charge-transfer complex, UV-Vis diffuse reflectance and FT-IR spectroscopies have been used. FT-IR characterization of TiO 2 samples in contact with the aqueous trans-ferulic acid solution indicates that the charge-transfer complex formation occurs via adsorption of bidentate ferulate species
The Role of Water in the Photocatalytic Degradation of Acetonitrile and Toluene in Gas-Solid and Liquid-Solid Regimes
Photocatalytic degradation of acetonitrile and toluene was carried out both in gas-solid and in liquid-solid regimes by using commercial TiO2 samples ( Merck and Degussa P25). The investigation was mainly aimed to study the influence of water present in the reaction environment on the mechanism and degradation rate of two probe molecules. In gas-solid regime, the reacting mixture consisted of toluene or acetonitrile, oxygen, nitrogen, and water vapour. The main degradation product of toluene was CO2 with small amounts of benzaldehyde. In the presence of water vapour, the activity of TiO2 Merck remained stable but greatly decreased if water was absent. TiO2 Degussa P25 continuously deactivated, even in the presence of water vapour. With both catalysts, the photodegradation products of acetonitrile were CO2 and HCN; the activity was stable and was independent of the presence of water vapour in the reacting mixture. The production of HCN represents a drawback of acetonitrile photocatalytic degradation but the elimination of HCN is not actually a problem. In liquid-solid regime, the main intermediates of toluene photodegradation were p-cresol and benzaldehyde; traces of pyrogallol and benzyl alcohol were also found. Benzoic acid, hydroquinone, and trans, trans muconic acid were detected only when TiO2 Merck was used. The photodegradation products of acetonitrile were cyanide, cyanate, formate, nitrate, and carbonate ions
Machine Learning-Based Models for Prediction of Toxicity Outcomes in Radiotherapy
In order to limit radiotherapy (RT)-related side effects, effective toxicity prediction and assessment schemes are essential. In recent years, the growing interest toward artificial intelligence and machine learning (ML) within the science community has led to the implementation of innovative tools in RT. Several researchers have demonstrated the high performance of ML-based models in predicting toxicity, but the application of these approaches in clinics is still lagging, partly due to their low interpretability. Therefore, an overview of contemporary research is needed in order to familiarize practitioners with common methods and strategies. Here, we present a review of ML-based models for predicting and classifying RT-induced complications from both a methodological and a clinical standpoint, focusing on the type of features considered, the ML methods used, and the main results achieved. Our work overviews published research in multiple cancer sites, including brain, breast, esophagus, gynecological, head and neck, liver, lung, and prostate cancers. The aim is to define the current state of the art and main achievements within the field for both researchers and clinicians
Radioablation +/- hormonotherapy for prostate cancer oligorecurrences (Radiosa trial): Potential of imaging and biology (AIRC IG-22159)
Background: Prostate cancer (PCa) is the second most common cancer among men. New imaging-modalities have increased the diagnosed patients with limited number of metastasis after primary curative therapy, introducing so-called oligometastatic state. Stereotactic body radiotherapy (SBRT) is emerging as a low-toxicity treatment to erase PCa localizations and postpone androgen deprivation therapy (ADT). A deeper understanding of the predictive role of biomarkers is desirable for a targeted treatment selection and surveillance programs. The aims of the RADIOSA trial are: Compare SBRT +/- ADT for oligorecurrent-castration-sensitive PCa (OCS-PCa) in terms of efficacy, toxicity and Quality of Life (QoL).Develop biology/imaging based prognostic tool that allows identifying OCS-PCa subclasses. Methods This is a randomized phase II clinical trial, recruiting 160 OCS-PCa in 3years, with progression-free survival (PFS) as primary endpoint. Three tasks will be developed: Randomized clinical study (3years for accrual and 2years for follow-up and data analysis);Imaging study, including imaging registration and METastasis Reporting and Data System (MET-RADS) criteria;Pre-clinical study, development of a biobank of blood samples for the analysis of neutrophil-to-lymphocyte ratio and preparatory for a subsequent miRNA profiling.We aim to determine which arm is justified for testing in a subsequent Phase III trial. A decision-tree algorithm, based on prognosis, biological phenotype and imaging profile, will be developed.
Discussion Recruiting will start in July 2019. SBRT will allow obtaining excellent PFS, local control, QoL and low toxicity. In SBRT arm, ADT deferral will allow for a drug-holiday, delaying the detrimental impact on QoL. A sufficient number of blood samples will be collected to perform biological patient profiling. A stratification tool will be established with an analysis of morphological and functional imaging, based on the use of MET-RADS criteria.So, in conclusion, RADIOSA aims to define the optimal management of bone/nodal PCa relapses in a SBRT regimen. This study will increase our knowledge on low-burden metastatic PCa in the era of high precision and high technology personalized medicine, offering highly effective therapy in terms of clinical outcome and cost-effectiveness.
Trial registration The RADIOSA study was prospectively registered at clinicaltrials.gov (NCT03940235, May 2019)
Validation of lung densitometry threshold at CT for the distinction between senile lung and emphysema in elderly subjects
Background and Aims. An ageing lung is characterised by distal airspace enlargement without alveolar wall destruction: therefore the anatomical distinction between senile lung and emphysema is clear-cut. In clinical settings the definition of precise boundaries between normalcy and pathology is more difficult with the risk of overdiagnosis. CT is an important diagnostic advancement in the field of COPD. Most methods for the evaluation of emphysema are based on the detection and measurement of areas characterised by a density level below a threshold assumed to characterize parenchymal destruction. Methods. Our retrospective study included 47 healthy subjects (65-91 years), 36 never smokers and 11 former smokers. As a reference sample we recruited 9 patients with emphysema (69-81 years). Thoracic scan was performed by single slice spiral CT and acquired without contrast enhancement. For each scan and on both lungs we sampled eighteen regions of interest in the upper, middle and lower field. Mean lung density (MLD) and lower limit of normal (LLN) of density distribution were calculated. Results. MLD for the whole study sample was -846±41 HU. -901 HU was the LLN of density distribution in the study sample. No significant correlation was noted between age and MLD. In the emphysematous sample the average lung density was -946±18 HU. The mean coefficient of variation was 3% in the healthy sample and 2% in the emphysematous one. The difference between groups was significant (p<0.0001). In one healthy subject only we measured a value slightly below the threshold reported in literature for conventional CT; no emphysematous value fell above the LLN. Conclusions. This study highlights the fact that in the elderly the threshold level of lung density commonly adopted in diagnostic algorithms of emphysema is fully applicable. When applying this method to older subjects the risk of misinterpreting areas of physiologic non-destructive reduction of density as emphysema is low
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