scholarly journals Composition and Modifications of Dental Implant Surfaces

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Michela Bruschi ◽  
Doris Steinmüller-Nethl ◽  
Walter Goriwoda ◽  
Michael Rasse
Keyword(s):  
Surface Energy ◽  
Dental Implant ◽  
Bone Cells ◽  
Bulk Material ◽  
Calcium Phosphates ◽  
Covalent Binding ◽  
Microarc Oxidation ◽  
Bioactive Molecules ◽  
Diamond Surface ◽  
Bulk Materials

Since Brånemark discovered the favorable effects of titanium in bone healing in 1965, titanium has emerged as the gold standard bulk material for present-time dental implantology. In the course of years researchers aimed for improvement of the implants performance in bone even at compromised implant sites and multiple factors were investigated influencing osseointegration. This review summarizes and clarifies the four factors that are currently recognized being relevant to influence the tissue-implant contact ratio: bulk materials and coatings, topography, surface energy, and biofunctionalization. The macrodesigns of bulk materials (e.g., titanium, zirconium, stainless steel, tantalum, and magnesium) provide the mechanical stability and their influence on bone cells can be additionally improved by surface treatment with various materials (calcium phosphates, strontium, bioglasses, diamond-like carbon, and diamond). Surface topography can be modified via different techniques to increase the bone-implant contact, for example, plasma-spraying, grit-blasting, acid-etching, and microarc oxidation. Surface energy (e.g., wettability and polarity) showed a strong effect on cell behavior and cell adhesion. Functionalization with bioactive molecules (via physisorption, covalent binding, or carrier systems) targets enhanced osseointegration. Despite the satisfying clinical results of presently used dental implant materials, further research on innovative implant surfaces is inevitable to pursuit perfection in soft and hard tissue performance.

Influence of temperature and humidity on the angle of repose of wood bulk materials

2016 ◽  
Author(s):  
И.В. Бачериков ◽  
Б.М. Локштанов
Keyword(s):  
Field Experiments ◽  
Bulk Material ◽  
Average Particle Size ◽  
Operating Conditions ◽  
Angle Of Repose ◽  
Wood Dust ◽  
Average Particle ◽  
Bulk Materials ◽  
Technical Literature ◽  
The Impact

При проектировании открытых и закрытых хранилищ измельченных сыпучих материалов древесных материалов, таких как щепа и опилки, большое значение имеет угол естественного откоса (статический и динамический) этих материалов. В технической литературе приводятся противоречивые сведения о величине этих углов, что приводит к ошибкам при проектировании складов. В справочных данных не учитываются условия, в которых эксплуатируются емкости для хранения сыпучих материалов, свойства и состояние этих сыпучих материалов. В свою очередь, ошибки при проектировании приводят к проблемам (зависание, сводообразование, «затопление» и т. д.) и авариям при эксплуатации бункеров и силосов на производстве. В статье представлены сведения, посвященные влиянию влажности и температуры на угол естественного откоса сыпучих материалов. На основании лабораторных и натурных экспериментов, проведенных с помощью специально разработанных методик и установок, была скорректирована формула для определения углов естественного откоса (статического и динамического) для измельченных древесных материалов в зависимости от их фракционного и породного состава, влажности (абсолютной и относительной) и температуры. При помощи скорректированной формулы можно определить угол естественного откоса древесных сыпучих материалов со среднегеометрическим размером частицы от 0,5 мм до 15 мм (от древесной пыли до технологической щепы) в различных производственных условиях. Статья может быть полезна проектировщикам при расчете угла наклона граней выпускающей воронки бункеров и силосов предприятий лесной отрасли и целлюлозо-бумажной промышленности. In the design of open and closed storage warehouses chopped wood materials for bulk materials such as wood chips and sawdust, great importance has an angle of repose (static and dynamic) of these materials. In the technical literature are conflicting reports about the magnitude of these angles, which leads to errors in the design of warehouses. In the referencesdoes not take into account the conditions under which operated capacities for storage of bulk materials, and properties and condition of the bulk material. The design errors lead to problems (hanging, arching, «flooding», etc.) and accidents in the operation of hoppers and silos at the mills. The article provides information on the impact of humidity and temperature on the angle of repose of granular materials. On the basis of laboratory and field experiments, conducted with the help of specially developed techniques and facilities has been adjusted formula for determining the angle of repose (static and dynamic) for the shredded wood materials depending on their fractional and species composition, humidity (absolute and relative) and temperature. It is possible, by using the corrected formula, to determine the angle of repose of loose wood materials with average particle size of from 0.5 mm to 15 mm (wood dust to pulpchips) in various operating conditions. The article can be helpful to designers in the calculation of the angle of inclination of the funnel faces produces bunkers and silos forest industries and pulp and paper industry.

The Role of Glyoxalase in Glycation and Carbonyl Stress Induced Metabolic Disorders

2020 ◽  
Vol 21 (9) ◽  
pp. 846-859
Author(s):  
Mohd Saeed ◽  
Mohd Adnan Kausar ◽  
Rajeev Singh ◽  
Arif J. Siddiqui ◽  
Asma Akhter
Keyword(s):  
Protein Misfolding ◽  
Covalent Binding ◽  
Critical Role ◽  
Enzymatic Reaction ◽  
Treatment Strategies ◽  
Bioactive Molecules ◽  
Carbonyl Stress ◽  
Defense System ◽  
Pathological Conditions ◽  
Age Related

Glycation refers to the covalent binding of sugar molecules to macromolecules, such as DNA, proteins, and lipids in a non-enzymatic reaction, resulting in the formation of irreversibly bound products known as advanced glycation end products (AGEs). AGEs are synthesized in high amounts both in pathological conditions, such as diabetes and under physiological conditions resulting in aging. The body’s anti-glycation defense mechanisms play a critical role in removing glycated products. However, if this defense system fails, AGEs start accumulating, which results in pathological conditions. Studies have been shown that increased accumulation of AGEs acts as key mediators in multiple diseases, such as diabetes, obesity, arthritis, cancer, atherosclerosis, decreased skin elasticity, male erectile dysfunction, pulmonary fibrosis, aging, and Alzheimer’s disease. Furthermore, glycation of nucleotides, proteins, and phospholipids by α-oxoaldehyde metabolites, such as glyoxal (GO) and methylglyoxal (MGO), causes potential damage to the genome, proteome, and lipidome. Glyoxalase-1 (GLO-1) acts as a part of the anti-glycation defense system by carrying out detoxification of GO and MGO. It has been demonstrated that GLO-1 protects dicarbonyl modifications of the proteome and lipidome, thereby impeding the cell signaling and affecting age-related diseases. Its relationship with detoxification and anti-glycation defense is well established. Glycation of proteins by MGO and GO results in protein misfolding, thereby affecting their structure and function. These findings provide evidence for the rationale that the functional modulation of the GLO pathway could be used as a potential therapeutic target. In the present review, we summarized the newly emerged literature on the GLO pathway, including enzymes regulating the process. In addition, we described small bioactive molecules with the potential to modulate the GLO pathway, thereby providing a basis for the development of new treatment strategies against age-related complications.

TRENDS AND CHALLENGES OF CARTILAGE TISSUE ENGINEERING

2009 ◽  
Vol 21 (03) ◽  
pp. 149-155 ◽  
Author(s):  
Hsu-Wei Fang
Keyword(s):  
Tissue Engineering ◽  
Stem Cells ◽  
Growth Factors ◽  
Bone Cells ◽  
Cartilage Tissue Engineering ◽  
Bioactive Molecules ◽  
In Vivo Studies ◽  
Cartilage Tissue

Cartilage injuries may be caused by trauma, biomechanical imbalance, or degenerative changes of joint. Unfortunately, cartilage has limited capability to spontaneous repair once damaged and may lead to progressive damage and degeneration. Cartilage tissue-engineering techniques have emerged as the potential clinical strategies. An ideal tissue-engineering approach to cartilage repair should offer good integration into both the host cartilage and the subchondral bone. Cells, scaffolds, and growth factors make up the tissue engineering triad. One of the major challenges for cartilage tissue engineering is cell source and cell numbers. Due to the limitations of proliferation for mature chondrocytes, current studies have alternated to use stem cells as a potential source. In the recent years, a lot of novel biomaterials has been continuously developed and investigated in various in vitro and in vivo studies for cartilage tissue engineering. Moreover, stimulatory factors such as bioactive molecules have been explored to induce or enhance cartilage formation. Growth factors and other additives could be added into culture media in vitro, transferred into cells, or incorporated into scaffolds for in vivo delivery to promote cellular differentiation and tissue regeneration.Based on the current development of cartilage tissue engineering, there exist challenges to overcome. How to manipulate the interactions between cells, scaffold, and signals to achieve the moderation of implanted composite differentiate into moderate stem cells to differentiate into hyaline cartilage to perform the optimum physiological and biomechanical functions without negative side effects remains the target to pursue.

scholarly journals In-Vitro Hemocompatibility of Polyaniline Functionalized by Bioactive Molecules

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1861 ◽  
Author(s):  
Skopalová ◽  
Capáková ◽  
Bober ◽  
Pelková ◽  
Stejskal ◽  
...  
Keyword(s):  
Surface Energy ◽  
Conducting Polymers ◽  
Human Blood ◽  
Sulfonic Acid ◽  
Electronic Conductivity ◽  
Bioactive Molecules ◽  
Sodium Dodecylbenzenesulfonate ◽  
Carboxylic Groups ◽  
Essential Prerequisite

Hemocompatibility is an essential prerequisite for the application of materials in the field of biomedicine and biosensing. In addition, mixed ionic and electronic conductivity of conducting polymers is an advantageous property for these applications. Heparin-like materials containing sulfate, sulfamic, and carboxylic groups may have an anticoagulation effect. Therefore, sodium dodecylbenzenesulfonate, 2-aminoethane-1-sulfonic acid and N-(2-acetamido)-2-aminoethanesulfonic acid were used for modification of the representative of conducting polymers, polyaniline, and the resulting products were studied in the context of interactions with human blood. The anticoagulation activity was then correlated to surface energy and conductivity of the materials. Results show that anticoagulation activity is highly affected by the presence of suitable functional groups originating from the used heparin-like substances, and by the properties of polyaniline polymer itself.

scholarly journals Vibrational Spectroscopy of Boron Nitride at High Temperatures and Pressures

1989 ◽  
Vol 162 ◽  
Author(s):  
Gregory Y. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Boron Nitride ◽  
Bulk Material ◽  
Hexagonal Phase ◽  
Bulk Materials ◽  
Lattice Thermal Expansion ◽  
Line Frequency ◽  
Nitride Coatings ◽  
Scattering Measurements ◽  
Sputter Deposited ◽  
Inherent Strain

ABSTRACTRaman scattering measurements are used to distinguish between amorphous and crystalline phases in sputter deposited boron nitride coatings and bulk materials. Changes in vibrational line frequency and linewidth can be attributed to differences in particle size or inherent strain which can be quantified from pressure-dependent measurements of the bulk material. The response of the Raman-allowed E2g modes (hexagonal phase) to temperature is described by a forced dampeg harmonic oscillator model from which the intra- and interplanar lattice thermal expansion can be estimated.

scholarly journals Au55, a stable glassy cluster: results of ab initio calculations

2017 ◽  
Vol 8 ◽  
pp. 2221-2229 ◽  
Author(s):  
Dieter Vollath ◽  
David Holec ◽  
Franz Dieter Fischer
Keyword(s):  
Surface Energy ◽  
Ab Initio ◽  
Experimental Result ◽  
Structure And Properties ◽  
Ab Initio Study ◽  
Bulk Materials ◽  
Coordination Numbers ◽  
Theoretical Approaches ◽  
Bulk Gold ◽  
Small Nanoparticles

Structure and properties of small nanoparticles are still under discussion. Moreover, some thermodynamic properties and the structural behavior still remain partially unknown. One of the best investigated nanoparticles is the Au55 cluster, which has been analyzed experimentally and theoretically. However, up to now, the results of these studies are still inconsistent. Consequently, we have carried out the present ab initio study of the Au55 cluster, using up-to-date computational concepts, in order to clarify these issues. Our calculations have confirmed the experimental result that the thermodynamically most stable structure is not crystalline, but it is glassy. The non-crystalline structure of this cluster was validated by comparison of the coordination numbers with those of a crystalline cluster. It was found that, in contrast to bulk materials, glass formation is connected to an energy release that is close to the melting enthalpy of bulk gold. Additionally, the surface energy of this cluster was calculated using two different theoretical approaches resulting in values close to the surface energy for bulk gold. It shall be emphasized that it is now possible to give a confidence interval for the value of the surface energy.

Structures and magnetic properties of Sm-Fe-N bulk magnets produced by the spark plasma sintering method

2007 ◽  
Vol 22 (11) ◽  
pp. 3130-3136 ◽  
Author(s):  
Tetsuji Saito
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Bulk Material ◽  
Decomposition Temperature ◽  
High Coercivity ◽  
Bulk Materials ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method ◽  
N Powder

Sm-Fe-N powders were successfully consolidated at 873 K and below by the spark plasma sintering (SPS) method. Although the decomposition temperature of the hard magnetic Sm2Fe17N3 phase has been reported to be 873 K, partial decomposition of the Sm2Fe17N3 phase was noted in the bulk materials obtained by sintering at below that temperature. The resultant bulk materials showed a coercivity of around 0.24 MAm−1, significantly lower than that of the original Sm-Fe-N powder. It was found that decomposition of the Sm2Fe17N3 phase in the SPS method was significantly lowered by the addition of a small amount of Zn powder to the Sm-Fe-N powder. The bulk material obtained by sintering a mixture of Sm-Fe-N and Zn powder (10%Zn) at 723 K exhibited high coercivity, comparable with that of the original Sm-Fe-N powder.

scholarly journals Programming function into mechanical forms by directed assembly of silk bulk materials

2016 ◽  
Vol 114 (3) ◽  
pp. 451-456 ◽  
Author(s):  
Benedetto Marelli ◽  
Nereus Patel ◽  
Thomas Duggan ◽  
Giovanni Perotto ◽  
Elijah Shirman ◽  
...  
Keyword(s):  
Self Assembly ◽  
Biological Function ◽  
Bulk Material ◽  
Directed Assembly ◽  
Water Soluble ◽  
Infrared Light ◽  
Bulk Materials ◽  
Protein Matrix ◽  
On Demand ◽  
Water Based

We report simple, water-based fabrication methods based on protein self-assembly to generate 3D silk fibroin bulk materials that can be easily hybridized with water-soluble molecules to obtain multiple solid formats with predesigned functions. Controlling self-assembly leads to robust, machinable formats that exhibit thermoplastic behavior consenting material reshaping at the nanoscale, microscale, and macroscale. We illustrate the versatility of the approach by realizing demonstrator devices where large silk monoliths can be generated, polished, and reshaped into functional mechanical components that can be nanopatterned, embed optical function, heated on demand in response to infrared light, or can visualize mechanical failure through colorimetric chemistries embedded in the assembled (bulk) protein matrix. Finally, we show an enzyme-loaded solid mechanical part, illustrating the ability to incorporate biological function within the bulk material with possible utility for sustained release in robust, programmably shapeable mechanical formats.

Modeling of Polarization-Specific Phonon Transmission Functions Through Interfaces

2008 ◽  
Author(s):  
Zhen Huang ◽  
Jayathi Murthy ◽  
Timothy Fisher
Keyword(s):  
Theoretical Prediction ◽  
Density Of States ◽  
Bulk Material ◽  
Transmission Function ◽  
Dissimilar Materials ◽  
Bulk Materials ◽  
Phonon Branch ◽  
Self Energy ◽  
Frequency Independent ◽  
Eigenvectors And Eigenvalues

The atomistic Green’s function (AGF) method has been used successfully in previous research to predict the transmission function for energy carriers at interfaces. In this work, the method is extended to capture the transmission function for each phonon polarization. The inputs for this extension are the same as for the original AGF method. Furthermore, this method does not require any complex manipulation of harmonic matrices and can be applied to different materials and geometries. The eigenvectors and eigenvalues of the overall density of states matrices are manipulated to yield the density of states matrix for each polarization. A decomposed self-energy is calculated from the density of states matrix for each polarization and used to calculate the transmission function for a particular phonon branch. In a pure bulk material such as silicon, each transmission function exhibits a frequency-independent value of unity, which matches the theoretical prediction. In heterogeneous bulk materials, the transmission function is reduced significantly due to the contact of dissimilar materials. The summation of the decomposed transmission functions is shown to reproduce the result from a direct AGF calculation in which all branches were treated together.

scholarly journals Renovation of Interest in the Magnetoelectric Effect in Nanoferroics

2018 ◽  
Vol 63 (11) ◽  
pp. 1006 ◽  
Author(s):  
M. D. Glinchuk ◽  
V. V. Khist
Keyword(s):  
Size Effects ◽  
Magnetoelectric Effect ◽  
Bulk Material ◽  
Bismuth Ferrite ◽  
Phenomenological Theory ◽  
Magnetoelectric Coupling ◽  
Theoretical Studies ◽  
Coupling Coefficients ◽  
Bulk Materials ◽  
Magnetoelectric Properties

Recent theoretical studies of the influence of the magnetoelectric effect on the physical properties of nanosized ferroics and multiferroics have been reviewed. Special attention is focused on the description of piezomagnetic, piezoelectric, and linear magnetoelectric effects near the ferroid surface in the framework of the Landau–Ginzburg–Devonshire phenomenological theory, where they are considered to be a result of the spontaneous surface-induced symmetry reduction. Therefore, nanosized particles and thin films can manifest pronounced piezomagnetic, piezoelectric, and magnetoelectric properties, which are absent for the corresponding bulk materials. In particular, the giant magnetoelectric effect induced in nanowires by the surface tension is possible. A considerable influence of size effects and external fields on the magnetoelectric coupling coefficients and the dielectric, magnetic, and magnetoelectric susceptibilities in nanoferroics is analyzed. Particular attention is paid to the influence of a misfit deformation on the magnetoelectric coupling in thin ferroic films and their phase diagrams, including the appearance of new phases absent in the bulk material. In the framework of the Landau–Ginzburg–Devonshire theory, the linear magnetoelectric and flexomagnetoelectric effects induced in nanoferroics by the flexomagnetic coupling are considered, and a significant influence of the flexomagnetic effect on the nanoferroic susceptibility is marked. The manifestations of size effects in the polarization and magnetoelectric properties of semiellipsoidal bismuth ferrite nanoparticles are discussed.

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