Bioceramics composition modulate resorption of human osteoclasts

Biomaterials used in bone regeneration are designed to be gradually resorbed by the osteoclast and replaced by new bone formed through osteoblastic activity. The aim of the present study is to analyze the role of osteoclasts in the resorption process. The attachment of human osteoclasts and the appearance of their resorption lacunae, when cultured on either the resorbable crystalline, calcium orthophosphate materials or on the long-term stable bioceramic material was investigated. The resorbable materials contain Ca₁₀[K,Na](PO₄)₇ (AW-Si) and Ca₂KNa(PO₄)₂ (GB14, GB9 & D9/25) as their main crystal phases, however they differ in their total solubility. These differences result from small variations in the composition. The long-term stable material consist of about 30% fluorapatite beside calcium zirconium phosphate (Ca₅(PO₄)3F + CaZr₄(PO₄)₆) and shows a very small solubility. AW-Si has an alkali containing crystalline phase, Ca₁₀[K,Na](PO₄). While GB14, GB9 and D9/25 contain the crystalline phase Ca₂KNa(PO₄)₂ with small additions of crystalline and amorphous diphosphates and/or magnesium potassium phosphate (GB14). D9/25 and AW-Si is less soluble compared to GB14, and GB9 among the resorbable materials. Resorbable and long-term stable materials vary in their chemical compositions, solubility, and surface morphology. Osteoclasts modified the surface in their attempts to resorb the materials irrespective of the differences in their physical and chemical properties. The depth and morphology of the resorption imprints were different depending on the type of material. These changes in the surface structure created by osteoclasts are likely to affect the way osteoblasts interact with the materials and how bone is subsequently formed.     

Das Verhalten linearer Induktionsmaschinen bei Überlichtgeschwindigkeit ihrer Wanderwellen

Übersicht Die Arbeit behandelt die Eigenschaften linearer Induktionsmaschinen unter der hier erstmalig gemachten Annahme, daß die Phasengeschwindigkeit der ständererregten Wanderwellen die Lichtgeschwindigkeit übertrifft. Der Untersuchung wird ein rotationssymmetrisches Zylindermodell der Maschine zugrunde gelegt. Sein elektromagnetisches Feld wird aus der achsialen Komponente eines Fitzgeraldschen Vektors hergeleitet, der radiale Zylinderwellen enthält. Zufolge von Resonanz der aufgedrückten Frequenz mit einer elektromagnetischen Eigenschwingung des von Ständer und Läufer eingeschlossenen Spaltgebietes vermag der Imaginärteil des komplexen Eingangsleitwertes positive und negative Werte anzunehmen, während sein Realteil stets positiv bleibt. Die Maschine arbeitet daher als Motor oder als Bremse, nicht jedoch als Generator.<hr>

Contents This paper deals with the properties of a linear induction machine under the assumption, made here for the first time, that the phase velocity of the stator-excited travelling waves surpasses light velocity. A cylindric, rotationally-symmetric model of the machine is used whose electromagnet field is deduced but from the axial component of Fitzgerald's vector. The solution of its partial differential equation shows the appearing of radially propagating waves. In accordance with the resonance of the imposed frequency to one of the electromagnetic eigenvibrations of the space separating the stator from the rotor the input admittance can change the sign of its imaginary component whereas its real component remains positive. Therefore the machine is able to performe the work of a motor or of a brake but not of a generator.

     

水性上光油疑难问题分析

目前,国内许多印刷厂家都已采用水性上光油,但是,在平版联机水性上光的过程中,经常会遇到许多问题.希望本文能帮助印刷厂解决实际生产中遇到的问题,提高生产效率.     

Progress Towards an Acoustic/Microwave Determination of the Boltzmann Constant at LNE-INM/CNAM

The Boltzmann constant k will be re-determined by using the simple, exact connection between the speed of sound in noble gases (extrapolated to zero pressure) and the thermodynamic temperature T, the molar mass of the gas M, and the universal gas constant R. The speed of sound will be determined in a spherical cavity of known volume V by measuring the acoustic resonance frequencies. This acoustic method led to the CODATA-recommended value of k; however, the CODATA value of k came from measurements using an almost perfectly spherical, stainless-steel-walled cavity filled with stagnant argon. The steel cavity’s volume was determined by weighing the mercury of well-known density required to fill it. In contrast, a copper-walled, quasi-spherical cavity (intentionally slightly deformed from a sphere), filled with helium gas that is continuously refreshed by a small helium flow that will mitigate the effects of outgassing, will be used. The volume of the copper cavity will be determined by measuring the microwave resonance frequencies and/or by three-dimensional coordinate measurements. If the microwave method is satisfactory, the measurement of k will be based on the ratio of the speed of sound in helium—obtained by acoustic resonance measurements—to the speed of light, obtained by microwave resonance measurements. This method exploits the theorem that the frequency ratios are independent of the details of the shape of the quasi-spherical cavity. Here, progress at LNE-INM/CNAM towards a better mechanical design and better understanding of the excess of the half-widths of the acoustic and microwave measurements are reported.     

Optimization of Advanced Live-Cell Imaging through Red/Near-Infrared Dye Labeling and Fluorescence Lifetime-Based Strategies

Fluorescence microscopy is essential for a detailed understanding of cellular processes; however, live-cell preservation during imaging is a matter of debate. In this study, we proposed a guide to optimize advanced light microscopy approaches by reducing light exposure through fluorescence lifetime (τ) exploitation of red/near-infrared dyes. Firstly, we characterized key instrumental elements which revealed that red/near-infrared laser lines with an 86x (Numerical Aperture (NA) = 1.2, water immersion) objective allowed high transmission of fluorescence signals, low irradiance and super-resolution. As a combination of two technologies, i.e., vacuum tubes (e.g., photomultiplier) and semiconductor microelectronics (e.g., avalanche photodiode), type S, X and R of hybrid detectors (HyD-S, HyD-X and HyD-R) were particularly adapted for red/near-infrared photon counting and τ separation. Secondly, we tested and compared lifetime-based imaging including coarse τ separation for confocal microscopy, fitting and phasor plot analysis for fluorescence lifetime microscopy (FLIM), and lifetimes weighting for enhanced stimulated emission depletion (STED) nanoscopy, in light of red/near-infrared multiplexing. Mainly, we showed that the choice of appropriate imaging approach may depend on fluorochrome number, together with their spectral/lifetime characteristics and STED compatibility. Photon-counting mode and sensitivity of HyDs together with phasor plot analysis of fluorescence lifetimes enabled the flexible and fast imaging of multi-labeled living H28 cells. Therefore, a combination of red/near-infrared dyes labeling with lifetime-based strategies offers new perspectives for live-cell imaging by enhancing sample preservation through acquisition time and light exposure reduction.