Global Existence Results and Uniqueness for Dislocation Equations

We are interested in nonlocal Eikonal Equations arising in the study of the dynamics of dislocations lines in crystals. For these nonlocal but also non monotone equations, only the existence and uniqueness of Lipschitz and local-in-time solutions were available in some particular cases. In this paper, we propose a definition of weak solutions for which we are able to prove the existence for all time. Then we discuss the uniqueness of such solutions in several situations, both in the monotone and non monotone case

Toward greener synthesis of WC powders for cemented tungsten carbides manufacturing

Tungsten carbide (WC) is the most important tungsten compound, and the main component of WC-Co cermet composites. WC-Co are widely used engineering materials due to the combination of high hardness and strength of tungsten carbide with the toughness and plasticity of the metallic binder. The direct synthesis of WC from tungsten concentrate containing ∼70% WO3 has been achieved by carbothermic reduction. Mineral/carbon black mixtures were prepared by planetary ball milling and subjected to annealing at 1150 °C in flowing Ar. Specific leaching treatments have been developed to remove foreign phases and obtain pure WC powders. This new process allows about 50% energy saving, -34% CO2 emissions, and significantly lower amounts of industrial waste, with respect to the classical hydrometallurgical tungsten extraction and subsequent pyrometallurgical WC synthesis, widely used in tungsten industry. WC powders obtained by carbothermic reduction of the mineral were employed to prepare sintered WC-8 wt %Co samples that showed high density (>99%), hardness (1490 HV), and toughness (14.6 MPa·m1/2). These findings demonstrate, for the first time, that the carbothermic reduction of tungsten concentrates does represent a viable process for energy efficient and sustainable synthesis of WC powders to be used in the production of cemented carbides

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Trasporti. Il modello Campania

intervista all'assessore ai trasporti della regione Campania Prof. Ing. E. Cascetta estensore del programma per le infrastrutture dell'Unione, delinea le direttrici di sviluppo di un settore che soffre di sottocapitalizzazione cronic