Testing machine learning algorithms for the prediction of depositional fluxes of the radionuclides 7Be, 210Pb and 40K.

The monthly depositional fluxes of 7Be, 210Pb and 40K were measured at Malaga, (Southern Spain) from 2005 to 2018. In this work, the depositional fluxes of these radionuclides are investigated and their relations with several atmospheric variables have been studied by applying two popular machine learning methods: Random Forest and Neural Network algorithms. We extensively test different configurations of these algorithms and demonstrate their predictive ability for reproducing depositional fluxes. The models derived with Neural Networks achieve slightly better results, in average, although similar, having into account the uncertainties. The mean Pearson-R coefficients, evaluated with a k-fold cross-validation method, are around 0.85 for the three radionuclides using Neural Network models, while they go down to 0.83, 0.79 and 0.8 for 7Be, 210Pb and 40K, respectively, for the Random Forest models. Additionally, applying the Recursive Feature Elimination technique we determine the variables more correlated with the depositional fluxes of these radionuclides, which elucidates the main dependences of their temporal variability.

Influence of ductal carcinoma in situ on the outcome of invasive breast cancer. A prospective cohort study.

BACKGROUND: Ductal carcinoma in situ (DCIS)-associated invasive ductal carcinoma (IDC) is present in a large number of patients with breast cancer. However, the association between these two entities has not been studied in detail. The aim of this study is to compare the clinical and histopathological factors associated to recurrence of IDC with those of DCIS-associated IDC (IDC + DCIS). MATERIALS AND METHODS: A prospective observational longitudinal study of 464 patients was performed between 2010 and 2015. Patients with IDC and DCIS + IDC were included and analyzed. RESULTS: IDC + DCIS was present in 243 patients (52.4%). No difference on histopathological characteristics were found, only Grade I and II of invasive component were more frequent in patients with IDC + DCIS than those with IDC (p  =  0.038). No differences on recurrence were found between the main groups (p = 0.256). For patients who received neoadjuvant chemotherapy, those with IDC + DCIS had lower response than those with IDC alone (p  =  0.014). No differences between the main groups were found on recurrence (p = 0.256). For patients who received neoadjuvant chemotherapy, recurrence was present in 19 patients (30.6%) in the IDC group in contrast to 5 (12.2%) in the IDC + DCIS group (p = 0.030). Mortality was present in 15 patients (24.2%) in the IDC group in contrast to 3 (7.3%) in the IDC + DCIS group (p = 0.027). At 7 years, 80.8% patients were alive: 71.9% from the IDC group and 92.7% from the IDC + DCIS group. CONCLUSIONS: The presence of DCIS seems to be indicative of a benign behavior in patients who receive neoadjuvant chemotherapy. Longer DFS and higher overall survival were found in the IDC + DCIS group despite presenting with a lower response to chemotherapy. These findings help us identify patients with better prognosis in breast cancer.

Dry sliding wear behaviour of ß-type Ti-Nb and Ti-Mo surfaces designed by diffusion treatments for biomedical applications.

The dry sliding wear behaviour of different Ti-Nb and Ti-Mo surfaces was investigated in order to evaluate the role of Nb and Mo ß-stabilizing elements in titanium wear resistance to consider them for biomedical applications. Dry sliding wear tests were performed under unlubricated conditions using a ball-on-plate tribometer (UMT) with reciprocating lineal movement of 1 Hz frequency at different loads (2 and 5 N) and against two counterface materials (alumina and stainless steel) to assess the effect of these parameters on wear. The results indicated an improvement in wear resistance for all the modified Ti surfaces. Metal-on-metal surfaces exhibited higher wear rate than ceramic-on-metal, and higher wear was observed for the more severe conditions. Wear rate values on modified surfaces were between 53% and 96% lower compared to pure Ti tested at 2 N, and up to 79% lower than Ti at 5 N. In both cases the highest wear reduction was observed for Ti-MoNH4Cl surface.

7Be, 210Pb and 40K depositions over 11 years in Málaga.

The monthly bulk depositional fluxes of three natural radionuclides (7Be, 210Pb and 40K) were measured at a Mediterranean coastal station (Málaga) over an 11-year period from 2005 to 2015. The mean annual depositional fluxes of 7Be, 210Pb and 40K were 1215, 144 and 67 Bq m-2 year-1 respectively, showing a clear seasonal trend with minimum values recorded during summer and maximum values in winter. The rainfall regime with dry summers allows estimating the dry deposition. Assuming constant dry deposition through each year, 7Be, 210Pb and 40K would account for 12.5, 26.5 and 33% of the bulk fallout respectively which indicates that deposition for 210Pb and 40K are significantly higher than 7Be. The precipitation-normalized enrichment factor alpha used to explain seasonal variations in the depositional fluxes of radionuclides with respect the rainfall, indicates higher depositional fluxes during spring and summer than expected from the amount of rainfall. Despite their different origin, 210Pb and 7Be monthly depositional fluxes have strong correlation. The atmospheric deposition fluxes of 7Be, 210Pb and 40K were controlled mainly by the amount of rainfall (r = 0.89, 0.91 and 0.66 respectively). Moreover, principal component analysis was applied to the datasets and deposition of radionuclides and rainfall in the same component highlighting the importance of the washout mechanism. The mean depositional velocity of aerosols evaluated using 7Be and 210Pb are similar and are compared to other published values.

Evaluation of the mechanical properties of powder metallurgy Ti-6Al-7Nb alloy.

Titanium and its alloys are common biomedical materials owing to their combination of mechanical properties, corrosion resistance and biocompatibility. Powder metallurgy (PM) techniques can be used to fabricate biomaterials with tailored properties because changing the processing parameters, such as the sintering temperature, products with different level of porosity and mechanical performances can be obtained. This study addresses the production of the biomedical Ti-6Al-7Nb alloy by means of the master alloy addition variant of the PM blending elemental approach. The sintering parameters investigated guarantee that the complete diffusion of the alloying elements and the homogenization of the microstructure is achieved. The sintering of the Ti-6Al-7Nb alloy induces a total shrinkage between 7.4% and 10.7% and the level of porosity decreases from 6.2% to 4.7% with the increment of the sintering temperature. Vickers hardness (280-300 HV30) and tensile properties (different combination of strength and elongation around 900MPa and 3%) are achieved.

Study of 7Be and ²¹°Pb as radiotracers of African intrusions in Malaga (Spain).

The relationship between the particulate matter in the atmosphere of Malaga and the origin of air masses with special attention to African intrusions was analyzed. The concentrations of PM10 and the activities of some radionuclides ((7)Be and (210)Pb) as tracers of these intrusions are discussed. The origin of these radiotracers is completely different. (210)Pb is a good tracer of air masses traveling close to the ground and come from inland areas. On the other hand, the production of (7)Be is very low in the vicinity of the Earth's surface, and increases with altitude, making it a great tracer of stratospheric air masses in the troposphere. Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of (7)Be and (210)Pb in aerosols at Malaga (36° 43' 40″ N; 4° 28' 8″ W) for the period 2009-2011 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory. The average concentration values of (7)Be and (210)Pb over the 3-year period have been found to be 5.05 and 0.55 mBq m(-3), respectively, with mean aerosol mass concentration of 53.6 µg m(-3). Taking into account the outbreaks of the daily values limits of PM10 in the study period (2009-2011), the origin of air masses is studied to explain three different situations of both radionuclides (7)Be and (210)Pb: 1) high concentrations of (7)Be and low concentrations of (210)Pb; 2) high concentrations of (210)Pb and low concentrations of (7)Be and 3) high concentrations of (7)Be and (210)Pb.

Feasibility study of the production of biomedical Ti-6Al-4V alloy by powder metallurgy.

Titanium and its alloys are characterized by an exceptional combination of properties like high strength, good corrosion resistance and biocompatibility which makes them suitable materials for biomedical prosthesis and devices. The wrought Ti-6Al-4V alloy is generally favored in comparison to other metallic biomaterials due to its relatively low elastic modulus and it has been long used to obtain products for biomedical applications. In this work an alternative route to fabricate biomedical implants made out of the Ti-6Al-4V alloy is investigated. Specifically, the feasibility of the conventional powder metallurgy route of cold uniaxial pressing and sintering is addressed by considering two types of powders (i.e. blended elemental and prealloyed). The characterization of physical properties, chemical analysis, mechanical behavior and microstructural analysis is carried out in-depth and the properties are correlated among them. On the base of the results found, the produced alloys are promising materials for biomedical applications as well as cheaper surgical devices and tools.

Behavior of ambient concentrations of natural radionuclides (7)Be, (210)Pb, (40)K in the Mediterranean coastal city of Málaga (Spain).

During a 4-year period (January 2009-December 2012), the (7)Be, (210)Pb, and (40)K activity concentrations in airborne particulate matter were weekly determined at the Málaga (Spain) located in the southern Iberian Peninsula. Totally 209 polypropylene filters were analyzed in the mentioned period. In 100% of the filters, (7)Be and (40)K activity concentrations were detected while (210)Pb activity concentration was detected in 96% of the filters. The results from individual measurements of (7)Be, (210)Pb, and (40)K concentrations were analyzed to derive the statistical estimates characterizing the distributions. Principal components analysis (PCA) was applied to the datasets and the results of the study reveal that aerosol behavior is represented by two principal components which explain 73.2% of total variance. Components PC1 and PC2 respectively explain 46.0 and 27.2% of total variance. PC1 was related positively to dust content, (7)Be and (40)K concentrations and negatively to sunspot numbers. In contrast, PC2 was related positively to temperature and (210)Pb activity and negatively to precipitation and relative humidity. The (7)Be levels showed a significant correlation with sunspot numbers due to the cosmogenic origin. (40)K activities showed a good correlation with dust deposition in filters mainly because it was transported to the air as resuspended particle from the soil. An inverse relationship was observed between the (210)Pb concentrations and monthly rainfall, indicating washout of atmospheric aerosols carrying these radionuclides and a pronounced positive correlation with the average monthly temperature of air.

Mechanical behaviour of pressed and sintered CP Ti and Ti-6Al-7Nb alloy obtained from master alloy addition powder.

The Ti-6Al-7Nb alloy was obtained using the blending elemental approach with a master alloy and elemental titanium powders. Both the elemental titanium and the Ti-6Al-7Nb powders were characterised using X-ray diffraction, differential thermal analysis and dilatometry. The powders were processed using the conventional powder metallurgy route that includes uniaxial pressing and sintering. The trend of the relative density with the sintering temperature and the microstructural evolution of the materials sintered at different temperatures were analysed using scanning electron microscopy and X-ray diffraction. A minimum sintering temperature of 1200°C has to be used to ensure the homogenisation of the alloying elements and to obtain a pore structure composed of spherical pores. The sintered samples achieve relative density values that are typical for powder metallurgy titanium and no intermetallic phases were detected. Mechanical properties comparable to those specified for wrought Ti-6Al-7Nb medical devices are normally obtained. Therefore, the produced materials are promising candidates for load bearing applications as implant materials.

Mechanical behaviour of pressed and sintered titanium alloys obtained from master alloy addition powders.

The fabrication of the workhorse Ti-6Al-4V alloy and of the Ti-3Al-2.5V alloy was studied considering the master alloy addition variant of the blending elemental approach conventionally used for titanium powder metallurgy. The powders were characterised by means thermal analysis and X-ray diffraction and shaped by means of uniaxial pressing. The microstructural evolution with the sintering temperature (900-1400 °C) was evaluated by SEM and EDS was used to study the composition. XRD patterns as well as the density by Archimedes method were also obtained. The results indicate that master alloy addition is a suitable way to fabricate well developed titanium alloy but also to produce alloy with the desired composition, not available commercially. Density of 4.3 g/cm³ can be obtained where a temperature higher than 1200 °C is needed for the complete diffusion of the alloying elements. Flexural properties comparable to those specified for wrought Ti-6Al-4V medical devices are, generally, obtained.

Mechanical behaviour of pressed and sintered titanium alloys obtained from prealloyed and blended elemental powders.

The applicability of irregular prealloyed Ti-6Al-4V powder for the fabrication of titanium products by pressing and sintering and its employment as a master alloy to obtain the Ti-3Al-2.5V alloy was studied. To this end, the starting powders were characterised by dilatometry, differential thermal analysis and XRD. Green samples were obtained by cold uniaxial pressing, and the evolution of the microstructure over the sintering temperature range 900-1400°C was studied. The variation of the final density and mechanical properties with the sintering temperature was considered. Based on the study carried out, it can be stated that more reliable powders are needed to open the titanium market to new applications. A relative density of 95% and diverse microstructural features and mechanical properties equivalent to those of biomedical devices can be obtained by the pressing and sintering route.

Mechanical properties and microstructural evolution of vacuum hot-pressed titanium and Ti-6Al-7Nb alloy.

Hot-pressing is a powder metallurgy process where loose powder is loaded into a mould, usually of graphite, and sintered by the simultaneous application of high temperature and pressure. In this study elemental titanium and Ti-6Al-7Nb alloy powders are hot-pressed under different conditions in order to study the influence of the processing parameters on the microstructure and mechanical properties. The samples are characterised in terms of relative density, microstructure, XRD, percentage of interstitials, three-point bending test and hardness. Relative densities as high as 99% are obtained, the oxygen and carbon content remains almost constant but nitrogen percentage increases. This is due to the interaction with the BN coated mould and leads to the formation of a reacted layer in the surface, composed by different titanium compounds, which greatly affect the mechanical properties. Nevertheless, the removal of this reacted layer leads to an important improvement of the ductility, especially for elemental titanium.

Chronic septal panniculitis caused by phaeohyphomycosis.

Panniculitis is caused by a heterogeneous group of clinical entities that tend to manifest themselves as erythematous-violaceous subcutaneous nodules on the legs. In addition to associations with rheumatic diseases including vasculitis, its causes may include various infections. The microorganisms most commonly involved are bacteria and fungi. Among the latter, Candida Sp,, Nocardia Sp., Sporotrichosis, cryptococcosis, histoplasmosis, cromomycosis, and inter alia, have been described. We present an immu-nocompetent patient with a persistent, neutrophilic, chronic septal panniculitis caused by Aureobasidium Pullulans, an infection-generating fungus belonging to the phaeohyphornycosis group. The patient was treated with amphotericin B 0.5 mg/kg/day, itraconazole 400 mg/day p.o., and 5 fluo-rocytosine 150 mg/kg/day for 4 weeks with excellent response.This is the first report in the literature on panniculitis caused by A. Pullulans's phaeohyphomycosis. We suggest that, whenever we observe patients with symptomatic panniculitis, especially if they are resistant to regular treatment, are of chronic course, and have neutrophilic infiltrates in their biopsies, panniculitis caused by uncommon organisms such as phaeohyphomycosis should be considered in the differential diagnosis.