A study on PDC drill bits quality

The quality of innovating PDC (Polycrystalline Diamond Compact) bits materials needs to be determined with accuracy by measuring cutting efficiency and wear rate, both related to the overall mechanical properties. An original approach is developed to encompass cutting efficiency and wear contribution to the overall sample quality. Therefore, a lathe-type test device was used to abrade specific samples from various manufacturers. Post-experiment analyzes are based on models establishing coupled relationships between cutting and friction stresses related to the drag bits excavation mechanism. These models are implemented in order to evaluate cutting efficiency and to estimate wear of the diamond insert. Phase analysis by XRD and finite element simulations were performed to explain the role of physicochemical parameters on the calculated quality factor values. Four main properties of PDC material were studied to explain quality results obtained in this study: cobalt content in samples that characterizes hardness/fracture toughness compromise, undesired phase as tungsten carbide weakening diamond structure, diamond grains sizes and residual stresses distribution affecting abrasion resistance

FLAG Review 2021

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiereWe review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor f+(0) arising in the semileptonic K→ π transition at zero momentum transfer, as well as the decay constant ratio fK/ fπ and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2) L× SU(2) R and SU(3) L× SU(3) R Chiral Perturbation Theory. We review the determination of the BK parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for mc and mb as well as those for the decay constants, form factors, and mixing parameters of charmed and bottom mesons and baryons. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant αs. We consider nucleon matrix elements, and review the determinations of the axial, scalar and tensor bilinears, both isovector and flavor diagonal. Finally, in this review we have added a new section reviewing determinations of scale-setting quantitie

A Novel Solid State Ultracapacitor

Novel dielectric materials were researched to develop an internal barrier layer capacitor that is fully solid state. These materials included reduced nanoparticles of barium titanate that were coated with various atomic layer deposited oxides. The nanoparticle powders were then densified into pellets and characterized using a dielectric test fixture over a frequency range of 20 Hz to 2 MHz. Densification and sintering were evaluated using scanning electron microscopic techniques. Ultimately, the samples showing the most promising electrical characteristics of permittivity, dissipation factor and equivalent series resistance were chosen to manufacture devices for subsequent testing

Selfoscillations of Suspended Carbon Nanotubes with a Deflection Sensitive Resistance under Voltage Bias

We theoretically investigate the electro-mechanics of a Suspended Carbon Nanotube with a Deflection Sensitive Resistance subjected to a homogeneous Magnetic Field and a constant Voltage Bias. We show that, (with the exception of a singular case), for a sufficiently high magnetic field the time-independent state of charge transport through the nanotube becomes unstable to selfexcitations of the mechanical vibration accompanied by oscialltions in the voltage drop and current across the nanotube.Comment: 4 pages, 1 figur

Understanding Bowtie Nanoantennas Excited by a Localized Emitter

A full analytical description of a bowtie nanoantenna excited by a localized emitter is presented using the transformation electromagnetic technique. By applying the conformal mapping, the bowtie nanoantenna is transformed into a periodic multi-parallel plate transmission line problem which can be easily evaluated analytically providing physical insight of the coupling between the dipole nanoemitter and the bowtie nanoantenna. The non-radiative Purcell enhancement spectrum is evaluated both analytically and numerically for different lengths, arm angles and metals, demonstrating a good agreement between both approaches. The method here presented fills the gap of the design techniques for optical nanoantennas

Deficiency of Kruppel-Like Factor KLF4 in Myeloid-Derived Suppressor Cells Inhibits Tumor Pulmonary Metastasis in Mice Accompanied by Decreased Fibrocytes

The importance of immunosuppressive myeloid-derived suppressor cells (MDSCs) bearing monocyte markers in tumor metastasis has been well established. Recently, it was reported that these cells possess phenotypic plasticity and differentiate into fibrocytes, very distinct cells that are precursors of tumorigenic myofibroblasts. However, the importance of this transdifferentiation in tumor metastasis has not been explored. Here, we describe the role of MDSC-derived fibrocytes in tumor metastasis that is regulated by Kruppel-like factor 4 (KLF4), a transcription factor that is critical to monocyte differentiation and to promotion of cancer development. Using mouse metastasis models of melanoma and breast cancer, we found that KLF4 knockout was associated with significantly reduced pulmonary metastasis, which was accompanied by decreased populations of MDSCs, fibrocytes and myofibroblasts in the lung. Cause-effect studies by adoptive transfer revealed that KLF4 deficiency in MDSCs led to significantly reduced lung metastasis that was associated with fewer MDSC-derived fibrocytes and myofibroblasts. Mechanistically, KLF4 deficiency significantly compromised the generation of fibrocytes from MDSCs in vitro. During this process, KLF4 expression levels were tightly linked with those of fibroblast-specific protein-1 (FSP-1), deficiency of which resulted in no metastasis in mice as has been previously reported. In addition, KLF4 bound directly to the FSP-1 promoter as determined by chromatin immunoprecipitation and overexpression of KLF4 increased the FSP-1 promoter activities. Taken together, our results suggest that MDSCs not only execute their immunosuppressive function to promote metastatic seeding as reported before, but also boost metastatic tumor growth after they adopt a fibrocyte fate. Therefore, KLF4-mediated fibrocyte generation from MDSCs may represent a novel mechanism of MDSCs contributing to tumor metastasis and supports the feasibility of inhibiting KLF4 or FSP-1 to prevent tumor metastasis

An extended communication inequalities approach to disparities in obesity preventive behaviors

This dissertation integrates the theory of planned behavior (TPB) with information exposure and concepts from the communication inequality perspective with the purpose of identifying disparities between the more and less advantaged segments of society throughout the communication for behavioral change process. It was expected to find differences in exposure to health information, as well as differences in the degree to which attitudes, norms, and perceived behavioral control (PBC) influence intentions, and the degree to which intentions lead to behavior. To test the hypotheses and research questions, structural equation modelling and multigroup analysis using MPlus 7.2 were conducted. Two datasets were analyzed, the first one from the Youth Media Campaign Longitudinal Survey (YMCLS), which was conducted with the purpose of assessing the effect of the VERB media campaign in a nationally representative sample of children aged 9 to 13 years and their parents between 2004 and 2006 (N = 2,773). The second study corresponds to a two-Wave survey among female adolescents conducted in schools in Santiago, Chile (N = 751). In the first study, the effect of exposure to the VERB campaign on the practice of physical activity two years later was examined through a mediation model. In the second study, the effect of seeking and scanning information about physical activity and fruit and vegetable consumption in the practice of the respective behaviors was examined, also with a mediation model. In the context of physical activity, across the two studies the main tenets of the TPB held, as norms and PBC were positive and significantly associated with intentions, which in turn led to the practice of the behavior. Furthermore, mediated effects of norms and PBC via intentions were supported in the two studies. The integration of the TPB with information exposure also received support in the two studies, with exposure to the VERB campaign being a significant predictor of attitudes and PBC, and indirectly influencing physical activity via PBC and intentions. In the Chile study, information scanning led to positive attitudes, norms, and PBC, and indirectly affected behavior though attitudes, PBC, and intentions. Information seeking, however, was negatively associated with behavior, both directly and mediated by other variables in the model. With respect to the disparities in the communication for behavioral change process it was found that children and adolescents from more disadvantaged backgrounds reported lower levels of exposure to the campaign and to health information. Moreover, subjects from more advantaged backgrounds were able to turn their intentions into behavioral change, whereas subjects from less advantaged backgrounds were not. Some results regarding the moderating role of social position indicators were unexpected for example, the positive association between exposure to the VERB campaign and attitudes only among children from less advantaged backgrounds. Taken together, the results of the two studies presented in this dissertation support an integration of the TPB with the concepts of information exposure and the moderation of social position indicators, as suggested by the communication inequality approach to better understand disparities in the communication for behavioral change process

Preliminary results from the STEPHI2009 campaign on the open cluster NGC 1817

We present preliminary observational results of the multi-site STEPHI campaign on the cluster NGC 1817. The three observatories involved are San Pedro Martir (Mexico), Xing Long (China) and the Observatorio del Teide (Spain) - giving an ideal combination to maximise the duty cycle. The cluster has 12 known delta Scuti stars and at least two detached eclipsing binary systems. This combination of characteristics is ideal for extracting information about global parameters of the targets, which will in turn impose strict constraints on the stellar models. From an initial comparison with stellar models using the known fundamental parameters, and just the observed pulsation frequencies and measured effective temperatures, it appears that a lower value of initial helium mass fraction will most likely explain the observations of these stars.Comment: 4 pages, proceedings from HELAS IV meeting 2010, Lanzarot