The ion-gas-neutral interactions with surfaces-2 (IGNIS-2) facility for the study of plasma-material interactions.

The Ion-Gas-Neutral Interactions with Surfaces-2 (IGNIS-2) surface science facility has been designed at the Pennsylvania State University with the specific purpose of enabling experiments to study plasma-material interactions. This in situ surface modification and characterization facility consists of multiple reconfigurable substations that are connected through a central transfer chamber. This fully connected vacuum system ensures that the physical and chemical properties of samples are not altered between surface modification and analysis. The modification techniques in IGNIS-2 include a low-energy (<300 eV), high-flux (up to 1016 cm-2 s-1) broad-beam ion source, a liquid metal dropper, a lithium injection system, an RF sputter source, and an evaporator. Its characterization techniques include charged particle-based techniques, such as low-energy ion scattering (enabled by two <5 keV ion sources) and x-ray photoelectron spectroscopy, and photon and light-based techniques, such as x-ray fluorescence, multi-beam optical stress sensors, and optical cameras. All of these techniques can be utilized up to mTorr pressures, allowing both in situ and in operando studies to be conducted. Results are presented on lithium wetting experiments of argon-irradiated tungsten-based composites, surface stress measurements of tungsten films during deuterium ion irradiation, and temperature-programmed desorption of deuterium-irradiated graphite to demonstrate the in situ capabilities of this new facility.

Reassigning CI chondrite parent bodies based on reflectance spectroscopy of samples from carbonaceous asteroid Ryugu and meteorites.

The carbonaceous asteroid Ryugu has been explored by the Hayabusa2 spacecraft to elucidate the actual nature of hydrous asteroids. Laboratory analyses revealed that the samples from Ryugu are comparable to unheated CI carbonaceous chondrites; however, reflectance spectra of Ryugu samples and CIs do not coincide. Here, we demonstrate that Ryugu sample spectra are reproduced by heating Orgueil CI chondrite at 300°C under reducing conditions, which caused dehydration of terrestrial weathering products and reduction of iron in phyllosilicates. Terrestrial weathering of CIs accounts for the spectral differences between Ryugu sample and CIs, which is more severe than space weathering that likely explains those between asteroid Ryugu and the collected samples. Previous assignments of CI chondrite parent bodies, i.e., chemically most primitive objects in the solar system, are based on the spectra of CI chondrites. This study indicates that actual spectra of CI parent bodies are much darker and flatter at ultraviolet to visible wavelengths than the spectra of CI chondrites.

Ion Bombardment-Induced Nanoarchitectonics on Polyetheretherketone Surfaces for Enhanced Nanoporous Bioactive Implants.

In spite of the biocompatible, nontoxic, and radiolucent properties of polyetheretherketone (PEEK), its biologically inert surface compromises its use in dental, orthopedic, and spine fusion industries. Many efforts have been made to improve the biological performance of PEEK implants, from bioactive coatings to composites using titanium alloys or hydroxyapatite and changing the surface properties by chemical and physical methods. Directed plasma nanosynthesis (DPNS) is an atomic-scale nanomanufacturing technique that changes the surface topography and chemistry of solids via low-energy ion bombardment. In this study, PEEK samples were nanopatterned by using argon ion irradiation by DPNS to yield active nanoporous biomaterial surface. PEEK surfaces modified with two doses of low and high fluence, corresponding to 1.0 × 1017 and 1.0 × 1018 ions/cm2, presented pore sizes of 15-25 and 60-90 nm, respectively, leaving exposed PEEK fibers and an increment of roughness of nearly 8 nm. The pores per unit area were closely related for high fluence PEEK and low fluence PEEK surfaces, with 129.11 and 151.72 pore/µm2, respectively. The contact angle significantly decreases in hydrophobicity-hydrophilicity tests for the irradiated PEEK surface to ∼46° from a control PEEK value of ∼74°. These super hydrophilic substrates had 1.6 times lower contact angle compared to the control sample revealing a rough surface of 20.5 nm only at higher fluences when compared to control and low fluences of 12.16 and 14.03 nm, respectively. These super hydrophilic surfaces in both cases reached higher cell viability with ∼13 and 34% increase, respectively, compared to unmodified PEEK, with an increased expression of alkaline phosphatase at 7 days on higher fluences establishing a higher affinity for preosteblasts with increased cellular activity, thus revealing successful and improved integration with the implant material, which can potentially be used in bone tissue engineering.

Analysis of Antibacterial Efficacy and Cellular Alignment Regulation on Plasma Nanotextured Chitosan Surfaces.

To address implant-related infections, antibacterial solutions specific to biomaterials are required to prevent bacterial proliferation. Traditional antibiotic usage has been found insufficient, motivating researchers to investigate alternative strategies such as surface modification and the application of antifouling or infection-resistant properties. A developing interest lies in designing surfaces that mimic natural antibacterial nanotopographies. In this study, we conducted a quantitative analysis of the outcomes from plasma nanotexturing, with particular emphasis on how the organization of topography influences antibacterial efficacy and the regulation of cell alignment. Plasma nanotexturing was applied to chitosan surfaces, which gradually transformed from nanopores to pillars and eventually into tilted pillars, as the plasma parameters (fluence and angle) increased. We used directed plasma nanosynthesis, a plasma-based technique that primarily induces topographical alterations on the surfaces. The surfaces were systematically characterized, incorporating methods such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). A comprehensive comparison of the nanotextures was executed by utilizing a trapezoidal method to calculate aspect ratios and assess texture orientation by examining the gaps in the nanostructures. We evaluated antibacterial properties against E. coli and S. aureus strains and assessed the survival and alignment of human bone marrow mesenchymal stem cells. Our findings reveal a significant reduction in bacterial adhesion (>80%) and growth on nanotextured surfaces, underscoring their potential for clinical applications. Moreover, we measured cell alignment, presenting the results in both a color-coded and numerical format to demonstrate the preferential alignment orientation induced specially by the tilted nanotexture. These insights highlight the profound impacts of plasma nanotexturing, indicating its potential for innovative biomedical applications such as advanced wound healing and tissue engineering.

Nanotextured porous titanium scaffolds by argon ion irradiation: Toward conformal nanopatterning and improved implant osseointegration.

Stress shielding and osseointegration are two main challenges in bone regeneration, which have been targeted successfully by chemical and physical surface modification methods. Direct irradiation synthesis (DIS) is an energetic ion irradiation method that generates self-organized nanopatterns conformal to the surface of materials with complex geometries (e.g., pores on a material surface). This work exposes porous titanium samples to energetic argon ions generating nanopatterning between and inside pores. The unique porous architected titanium (Ti) structure is achieved by mixing Ti powder with given amounts of spacer NaCl particles (vol % equal to 30%, 40%, 50%, 60%, and 70%), compacted and sintered, and combined with DIS to generate a porous Ti with bone-like mechanical properties and hierarchical topography to enhance Ti osseointegration. The porosity percentages range between 25% and 30% using 30 vol % NaCl space-holder (SH) volume percentages to porosity rates of 63%-68% with SH volume of 70 vol % NaCl. Stable and reproducible nanopatterning on the flat surface between pores, inside pits, and along the internal pore walls are achieved, for the first time on any porous biomaterial. Nanoscale features were observed in the form of nanowalls and nanopeaks of lengths between 100 and 500 nm, thicknesses of 35-nm and heights between 100 and 200 nm on average. Bulk mechanical properties that mimic bone-like structures were observed along with increased wettability (by reducing contact values). Nano features were cell biocompatible and enhanced in vitro pre-osteoblast differentiation and mineralization. Higher alkaline phosphatase levels and increased calcium deposits were observed on irradiated 50 vol % NaCl samples at 7 and 14 days. After 24 h, nanopatterned porous samples decreased the number of attached macrophages and the formation of foreign body giant cells, confirming nanoscale tunability of M1-M2 immuno-activation with enhanced osseointegration.

HEDOS-a computational tool to assess radiation dose to circulating blood cells during external beam radiotherapy based on whole-body blood flow simulations.

We have developed a time-dependent computational framework, hematological dose (HEDOS), to estimate dose to circulating blood cells from radiation therapy treatment fields for any treatment site. Two independent dynamic models were implemented in HEDOS: one describing the spatiotemporal distribution of blood particles (BPs) in organs and the second describing the time-dependent radiation field delivery. A whole-body blood flow network based on blood volumes and flow rates from ICRP Publication 89 was simulated to produce the spatiotemporal distribution of BPs in organs across the entire body using a discrete-time Markov process. Constant or time-varying transition probabilities were applied and their impact on transition time was investigated. The impact of treatment time and anatomical site were investigated using imaging data and dose distributions from a liver cancer and a brain cancer patient. The simulations revealed different dose levels to the circulating blood for brain irradiation compared to liver irradiation even for similar field sizes due to the different blood flow properties of the two organs. The volume of blood receiving any dose (V>0 Gy) after a single radiation fraction increases from 1.2% for a 1 s delivery time to 20.9% for 120 s delivery time for the brain cancer treatment, and from 10% (1 s) to 48.7% (120 s) for a liver cancer treatment. Other measures of the low-dose bath to the circulating blood such as the dose to small volumes of blood (D2%) decreases with longer delivery time. Furthermore, we demonstrate that the blood dose-volume histogram is highly sensitive to changes in the treatment time, indicating that dynamic modeling of blood flow and radiation fields is necessary to evaluate dose to circulating blood cells for the assessment of radiation-induced lymphopenia. HEDOS is publicly available and allows for the estimation of patient-specific dose to circulating blood cells based on organ DVHs, thus enabling the study of the impact of different treatment plans, dose rates, and fractionation schemes.

Dossier temático: ingeniería de tejidos en odontología / Thematic Dossier: Tissue Engineering in Dentistry

La odontología no se ha marginado de los grandes y rápidos cambios que han tenido las ciencias debido a la globalización. La ingeniería biomédica, la ingeniería de tejidos y la biología molecular, entre otras disciplinas, trabajan conjuntamente para aportar nuevas alternativas terapéuticas que repliquen la anatomía, fisiología y función de los tejidos u órganos afectados por patología, trauma o alteraciones de desarrollo.

A Reliable and Reproducible Model for Assessing the Effect of Different Concentrations of α-Solanine on Rat Bone Marrow Mesenchymal Stem Cells.

Αlpha-solanine (α-solanine) is a glycoalkaloid present in potato (Solanum tuberosum). It has been of particular interest because of its toxicity and potential teratogenic effects that include abnormalities of the central nervous system, such as exencephaly, encephalocele, and anophthalmia. Various types of cell culture have been used as experimental models to determine the effect of α-solanine on cell physiology. The morphological changes in the mesenchymal stem cell upon exposure to α-solanine have not been established. This study aimed to describe a reliable and reproducible model for assessing the structural changes induced by exposure of mouse bone marrow mesenchymal stem cells (MSCs) to different concentrations of α-solanine for 24 h. The results demonstrate that nonlethal concentrations of α-solanine (2-6 µM) changed the morphology of the cells, including an increase in the number of nucleoli, suggesting elevated protein synthesis, and the formation of spicules. In addition, treatment with α-solanine reduced the number of adherent cells and the formation of colonies in culture. Immunophenotypic characterization and staining of MSCs are proposed as a reproducible method that allows description of cells exposed to the glycoalkaloid, α-solanine.

Sistema Brãnemark Novum: Un moderno concepto en implantes para mandíbulas edéntulas / Brãnemark Novum System: A modern concept for implant restorattion of edentolus mandibles

El sistema Brãnemark Novun es una técnica que permite la reducción de tiempos quirúrgicos y protésicos con una menor agresión al paciente. Es una técnica que proporciona una solución prácticamente inmediata tanto estética como funcional...

Evaluación de la reproducibilidad de tres articuladores a nivel dental / Evaluation of the reproducibility in three articulators at tooth level

El objetivo de esta investigación fue cuantificar la reproducción de los registros obtenidos en los articuladores 2240 y 3040 (Whip-Mix) con los registros obtenidos en un articulador Stuart (73) como instrumento control, para evaluar la exactitud de reproducción de los movimientos bordeantes mandibulares en los tres planos del espacio. Se obtuvieron registros para realizar la programación en los tres articuladores y un juego de modelos dentales con bases removibles para cada uno de los nueve casos programados; esto permitió montar y transferir con exactitud los modelos entre articuladores. Un aparato trazador fue posicionado a nivel de la cúspide bucal media del primer molar mandibular derecho de cada modelo, el cual trazó el patrón de movimiento de la cúspide en los tres planos del espacio. Los trazos fueron fotografiados usando un técnica estandarizada, y los negativos se proyectaron con una magnificación estándar sobre una impresión de un metro cuadrado exacto con círulos concéntricos de un radio de 25mm. en incremento entre los intervalos; esto con el fin de dividir los trazos en intervalos para realizar las medicines. Los promedios de las variacioene se analizaron con tres tipos de pruebas estadísticas, determinando las fuentes de variación entre los trazos representativos. Los resultados de las pruebas indicaron que las diferencias no eran estadísticamente significativas pero la reproducibilidad de los movimientos bordeantes del araticulador ajustable de Stuart con los articuladores Whip-Mix es clínicamente diferente, presentando mayores discrepancias el intrumento 3040 sobre el instrumento semiajustable 2240