Universal binding-energy relation for crystals that accounts for surface relaxation

We present a universal relation for crack surface cohesion including surface relaxation. Specifically, we analyze how N atomic planes respond to an opening displacement at its boundary, producing structurally relaxed surfaces. Via density-functional theory, we verify universality for metals (Al), ceramics (α−Al_2O_3), and semiconductors (Si). When the energy and opening displacement are scaled appropriately with respect to N, the uniaxial elastic constant, the relaxed surface energy, and the equilibrium interlayer spacing, all energy-displacement curves collapse onto a single universal curve

Electrical stimulation to promote osseointegration of bone anchoring implants: a topical review

Electrical stimulation has shown to be a promising approach for promoting osseointegration in bone anchoring implants, where osseointegration defines the biological bonding between the implant surface and bone tissue. Bone-anchored implants are used in the rehabilitation of hearing and limb loss, and extensively in edentulous patients. Inadequate osseointegration is one of the major factors of implant failure that could be prevented by accelerating or enhancing the osseointegration process by artificial means. In this article, we reviewed the efforts to enhance the biofunctionality at the bone-implant interface with electrical stimulation using the implant as an electrode. We reviewed articles describing different electrode configurations, power sources, and waveform-dependent stimulation parameters tested in various in vitro and in vivo models. In total 55 English-language and peer-reviewed publications were identified until April 2020 using PubMed, Google Scholar, and the Chalmers University of Technology Library discovery system using the keywords: osseointegration, electrical stimulation, direct current and titanium implant. Thirteen of those publications were within the scope of this review. We reviewed and compared studies from the last 45\ua0years and found nonuniform protocols with disparities in cell type and animal model, implant location, experimental timeline, implant material, evaluation assays, and type of electrical stimulation. The reporting of stimulation parameters was also found to be inconsistent and incomplete throughout the literature. Studies using in vitro models showed that osteoblasts were sensitive to the magnitude of the electric field and duration of exposure, and such variables similarly affected bone quantity around implants in in vivo investigations. Most studies showed benefits of electrical stimulation in the underlying processes leading to osseointegration, and therefore we found the idea of promoting osseointegration by using electric fields to be supported by the available evidence. However, such an effect has not been demonstrated conclusively nor optimally in humans. We found that optimal stimulation parameters have not been thoroughly investigated and this remains an important step towards the clinical translation of this concept. In addition, there is a need for reporting standards to enable meta-analysis for evidence-based treatments

Directed Irradiation Synthesis as an Advanced Plasma Technology for Surface Modification to Activate Porous and “as-received” Titanium Surfaces

For the design of smart titanium implants, it is essential to balance the surface properties without any detrimental effect on the bulk properties of the material. Therefore, in this study, an irradiation-driven surface modification called directed irradiation synthesis (DIS) has been developed to nanopattern porousand“as-received”c.p. Tisur faces with the aim of improving cellular viability. Nano features were developed using singly-charged argon ions at 0.5 and 1.0 keV energies, incident angles from 0◦ to 75◦ degrees, and fluences up to 5.0×1017 cm−2. Irradiated surfaces were evaluated by scanning electron microscopy, atomic force microscopy and contact angle, observing an increased hydrophilicity (a contact angle reduction of 73.4% and 49.3%) and a higher roughness on both surfaces except for higher incident angles, which showed the smoothest surface. In-vitro studies demonstrated the biocompatibility of directed irradiation synthesis (DIS) reaching 84% and 87% cell viability levels at 1 and 7 days respectively, and a lower percentage of damaged DNA in tail compared to the control c.p. Ti. All these results confirm the potential of the DIS technique to modify complex surfaces at the nanoscale level promoting their biological performance.Department of Defense (Spain) contract W81XWH-11-2-0067Ministry of Economy and Competitiveness of Spain grant MAT2015-71284-

Enhancing osteoblast survival through pulsed electrical stimulation and implications for osseointegration

Electrical stimulation has been suggested as a means for promoting the direct structural and functional bonding of bone tissue to an artificial implant, known as osseointegration. Previous work has investigated the impact of electrical stimulation in different models, both in vitro and in vivo, using various electrode configurations for inducing an electric field with a wide range of stimulation parameters. However, there is no consensus on optimal electrode configuration nor stimulation parameters. Here, we investigated a novel approach of delivering electrical stimulation to a titanium implant using parameters clinically tested in a different application, namely peripheral nerve stimulation. We propose an in vitro model comprising of Ti6Al4V implants precultured with MC3T3-E1 preosteoblasts, stimulated for 72\ua0h at two different pulse amplitudes (10\ua0\ub5A and 20\ua0\ub5A) and at two different frequencies (50\ua0Hz and 100\ua0Hz). We found that asymmetric charge-balanced pulsed electrical stimulation improved cell survival and collagen production in a dose-dependent manner. Our findings suggest that pulsed electrical stimulation with characteristics similar to peripheral nerve stimulation has the potential to improve cell survival and may provide a promising approach to improve peri-implant bone healing, particularly to neuromusculoskeletal interfaces in which implanted electrodes are readily available

Density-functional-theory-based local quasicontinuum method: Prediction of dislocation nucleation

We introduce the density functional theory (DFT) local quasicontinuum method: a first principles multiscale material model that embeds DFT unit cells at the subgrid level of a finite element computation. The method can predict the onset of dislocation nucleation in both single crystals and those with inclusions, although extension to lattice defects awaits new methods. We show that the use of DFT versus embedded-atom method empirical potentials results in different predictions of dislocation nucleation in nanoindented face-centered-cubic aluminum

Importance of Shear in the bcc-to-hcp Transformation in Iron

Iron shows a pressure-induced martensitic phase transformation from the ground state ferromagnetic bcc phase to a nonmagnetic hcp phase at ≈13 GPa. The exact transformation pressure (TP) and pathway are not known. Here we present a multiscale model containing a quantum-mechanics-based multiwell energy function accounting for the bcc and hcp phases of Fe and a construction of kinematically compatible and equilibrated mixed phases. This model suggests that shear stresses have a significant influence on the bcc↔hcp transformation. In particular, the presence of modest shear accounts for the scatter in measured TPs. The formation of mixed phases also provides an explanation for the observed hysteresis in TP

Integrating Social Justice Practices into Graduate Training: Collaborating with Stakeholders to Adapt Professional Development in Puerto Rico

Treating trauma has become an international social justice concern, with increasing numbers of graduate training programs prioritizing how to conceptualize needs and interventions within a trauma-informed framework. Minimal research and guidelines exist for adapting these trauma-informed practices for the local community context. Additionally, trauma-informed practices often fail to consider ongoing structural issues faced by oppressed communities such as poverty and racism. Social work, psychology, and counseling graduate training programs often rely on a cultural competency framework instead of a social justice framework that addresses racism and Whiteness. During our graduate Counseling and School Psychology training program at the University of Massachusetts Boston, we collaborated with stakeholders at a school and community center in San Juan, Puerto Rico to culturally adapt and deliver trainings in trauma-informed practices for staff using an ecological validity framework. Using our work in Puerto Rico as a case study, this paper addresses the cultural adaptation of trauma-informed practices and factors to consider when implementing trauma-informed practices, emphasizing the need for creating safety. Strategies for embedding this trauma-informed work into mental health graduate training programs and recommendations for working with individuals from marginalized groups in school settings are discussed

Atención psicológica y apoyo educativo a las personas afiliadas a la Fundación Familias de Esperanza

Eps 883 Brindar atención psicológica y apoyo educativo a las personas afiliadas a la Fundación Familias de Esperanza. El Ejercicio Profesional Supervisado, se desarrolló en la Fundación Familias de Esperanza, Organización no Gubernamental que provee servicios de educación, salud y vivienda a personas de escasos recursos en el área de Sacatepéquez, donde se encuentra ubicada la fundación, a dos kilómetros del municipio de Antigua Guatemala. La población atendida proviene del municipio de Sacatepéquez, de las 14 aldeas y barrios en donde la viven las personas afiliadas a la Fundación, se trabajó con las familias afiliadas tanto con niños como adolescentes y también adultos. Para el desarrollo sistematizado del Ejercicio Profesional Supervisado, se dividió en tres grandes ejes: Acciones de Atención Directa, Acciones de Formación y Proceso Investigativo Cualitativo. Las acciones de Atención Directa fueron orientadas a brindar atención a niños y niñas, adolescentes y adultos referidos por las diferentes gerencias de la Fundación para evaluación y tratamiento psicológico o psicoeducativo. Las acciones de formación estuvieron encaminadas al fortalecimiento y crecimiento de las personas que trabajan directamente con el niño o niña afectada, es decir con los padres de los mismos. EL proceso Investigativo fue dirigido a conocer los factores psicosociales que contribuyen a la modificación de patrones de crianza de las familias participantes en el programa de Crianza con Cariño

Atención integral y prevención primaria en el ámbito escolar a los problemas del habla y del lenguaje de los niños afiliados a la Fundación Familias de Esperanza.

Resumen Atender integralmente y brindar prevención primaria en el ámbito escolar a los problemas del habla y del lenguaje de los niños afiliados a la Fundación Familias de Esperanza. Ejercicio Técnico Supervisado de la carrera técnica de Terapia del Lenguaje, se desarrollado en la Fundación Familias de Esperanza, organización no gubernamental que presta servicios de educación, salud y vivienda a personas de escasos recursos en el área de Sacatepéquez. Ubicada a dos kilómetros del municipio de Antigua Guatemala. La población atendida proviene del municipio de Sacatepéquez, de las 14 aldeas y barrios en donde la fundación tiene niños afiliados, así mismo se trabajó con los padres de familia de los niños en el programa de Terapia del Lenguaje y con maestras de preprimaria y primero primaria de la Escuela Oficial Rural Mixta de San Pedro las Huertas. Se desarrolló en tres grandes ejes: Acciones de atención directa. Acciones de formación. Proceso investigativo cualitativo. Las acciones de Atención Directa se dedicaron a brindar atención a niños, niñas, adolescentes y adultos afiliados referidos por problemas del lenguaje o del habla, dentro de las instalaciones de la Fundación. Las acciones de formación fueron encaminadas al fortalecimiento y crecimiento de las personas que trabajan directamente con el niño o niña afectada, es decir con los padres y maestros de los mismos. el proceso Investigativo se dirigió a conocer los factores psicosociales que contribuyen a la falta de prevención primaria de los problemas del habla y del lenguaje en el ámbito escolar preprimaria y de primero primaria de la Escuela de San Pedro las Huerta