Effects of LP-MOCVD prepared TiO2 thin films on the in vitro behavior of gingival fibroblasts

We report on the in vitro response of human gingival fibroblasts (HGF-1 cell line) to various thin films of titanium dioxide (TiO2) deposited on titanium (Ti) substrates by low pressure metal-organic chemical vapor deposition (LP-MOCVD). The aim was to study the influence of film structural parameters on the cell behavior comparatively with a native-oxide covered titanium specimen, this objective being topical and interesting for materials applications in implantology. HGF-1 cells were cultured on three LP-MOCVD prepared thin films of TiO2 differentiated by their thickness, roughness, transversal morphology, allotropic composition and wettability, and on a native-oxide covered Ti substrate. Besides traditional tests of cell viability and morphology, the biocompatibility of these materials was evaluated by fibronectin immunostaining, assessment of cell proliferation status and the zymographic evaluation of gelatinolytic activities specific to matrix metalloproteinases secreted by cells grown in contact with studied specimens. The analyzed surfaces proved to influence fibronectin fibril assembly, cell proliferation and capacity to degrade extracellular matrix without considerably affecting cell viability and morphology. The MOCVD of TiO2 proved effective in positively modifying titanium surface for medical applications. Surface properties playing a crucial role for cell behavior were the wettability and, secondarily, the roughness, HGF-1 cells preferring a moderately rough and wettable TiO2 coating

Net emission of ArH2He thermal plasmas at atmospheric pressure

International audienceThe Net Emission Coefficient (NEC) has been calculated for Ar-H 2 -He thermal plasmas and for a temperature range from 5000K to 30000K. The plasma is supposed to be in Local Thermodynamic Equilibrium (LTE) at atmospheric pressure. This study takes into account the radiation resulting from the atomic continuum, the molecular continuum, and the atomic lines. A particular attention has been paid to the treatment of helium lines broadenings. The results of net emission coefficients are presented for pure gases and Ar-H 2 -He mixtures. Radiation is weak in pure helium at low temperatures because of the high ionization energy of this species. On the opposite, at very high temperature, the influence of hydrogen tends to decrease because ionic lines do not exist for this last species. Finally, a small proportion of helium in Ar-H 2 mixtures does not change the net emission coefficient because of the weak intensity of the helium lines

MOCVD-Fabricated TiO2 Thin Films: Influence of Growth Conditions on Fibroblast Cells Culture

TiO2 thin films with various morphologies were grown on Ti substrates by the LP-MOCVD technique (Low Pressure Chemical Vapour Deposition from Metal-Organic precursor), with titanium tetra-iso-propoxide as a precursor. All the films were prepared in the same conditions except the deposition time. They were characterized by X-ray diffraction, scanning electron microscopy, optical 15 interferometry, water contact angle measurements. MOCVD-fabricated TiO2 thin films are known to be adapted to cell culture for implant requirements. Human gingival fibroblasts were cultured on the various TiO2 deposits. Differences in cell viability (MTT tests) and cell spreading (qualitative assessment) were observed and related to film roughness, wettability and allotropic composition

Magnetic Properties of Quantum Ferrimagnetic Spin Chains

Magnetic susceptibilities of spin-$(S,s)$ ferrimagnetic Heisenberg chains are numerically investigated. It is argued how the ferromagnetic and antiferromagnetic features of quantum ferrimagnets are exhibited as functions of $(S,s)$. Spin-$(S,s)$ ferrimagnetic chains behave like combinations of spin-$(S-s)$ ferromagnetic and spin-$(2s)$ antiferromagnetic chains provided $S=2s$.Comment: 4 pages, 7 PS figures, to appear in Phys. Rev. B: Rapid Commu

ROSAT observations of X-ray emission from planetary nebulae

We have searched the entire ROSAT archive for useful observations to study X-ray emission from Galactic planetary nebulae (PNs). The search yields a sample of 63 PNs, which we call the ROSAT PN sample. About 20-25% of this sample show X-ray emission; these include 13 definite detections and three possible detections (at a 2-sigma level). All X-ray sources in these PNs are concentrated near the central stars. Only A 30, BD+30 3639, and NGC 6543 are marginally resolved by the ROSAT instruments. Three types of X-ray spectra are seen in PNs. Type 1 consists of only soft X-ray emission (<0.5 keV), peaks at 0.1-0.2 keV, and can be fitted by blackbody models at temperatures 1-2 10^5 K. Type 2 consists of harder X-ray emission, peaks at >0.5 keV, and can be fitted by thin plasma emission models at temperatures of a few 10^6 K. Type 3 is a composite of a bright Type 1 component and a fainter Type 2 component. Unresolved soft sources with Type 1 spectra or the soft component of Type 3 spectra are most likely photospheric emission from the hot central stars. Absorption cross sections are large for these soft-energy photons; therefore, only large, tenuous, evolved PNs with hot central stars and small absorption column densities have been detected. The origin of hard X-ray emission from PNs is uncertain. PNs with Type 2 spectra are small, dense, young nebulae with relatively cool (<<10^5 K) central stars, while PNs with Type 3 X-ray spectra are large, tenuous, evolved nebulae with hot central stars. The hard X-ray luminosities are also different between these two types of PNs, indicating perhaps different origins of their hard X-ray emission. Future Chandra and XMM observations with high spatial and spectral resolution will help to understand the origin of hard X-ray emission from PNs.Comment: To be published in The Astrophysical Journal Supplement Series. 21 pages, 7 figures, 5 table

Non-equilibrium plasma properties of electric arc discharge in air between copper electrodes

Spectroscopy investigations of plasma of free burning electric arc discharge as well as discharge in air flow of 6.45 slpm at currents 3.5, 30, 50 and 100 A were carried out. Plasma state deviation from thermodynamic equilibrium was found at arc current 100 A. Two-temperatures model was used to estimate plasma composition at arc current 100 A.Выполнены спектроскопические исследования плазмы свободно горящего электродугового разряда, а также разряда в потоке воздуха 6,45 л/мин при силах тока 3,5, 30, 50 и 100 А. Установлено отклонение состояния плазмы от термодинамического равновесия при силе тока 100 А. Использована двухтемпературная модель для оценки состава плазмы при силе тока 100 А.Виконані спектроскопічні дослідження плазми вільно існуючого електродугового розряду, а також, розряду в потоці повітря 6,45 л/хв при силах струму 3,5, 30, 50 и 100 А. Встановлено відхилення стану плазми від термодинамічної рівноваги при силі струму 100 А. Використано двотемпературну модель для оцінки складу плазми при силі струму 100 А

Molecular basis of Diamond–Blackfan anemia: structure and function analysis of RPS19

Diamond–Blackfan anemia (DBA) is a rare congenital disease linked to mutations in the ribosomal protein genes rps19, rps24 and rps17. It belongs to the emerging class of ribosomal disorders. To understand the impact of DBA mutations on RPS19 function, we have solved the crystal structure of RPS19 from Pyrococcus abyssi. The protein forms a five α-helix bundle organized around a central amphipathic α-helix, which corresponds to the DBA mutation hot spot. From the structure, we classify DBA mutations relative to their respective impact on protein folding (class I) or on surface properties (class II). Class II mutations cluster into two conserved basic patches. In vivo analysis in yeast demonstrates an essential role for class II residues in the incorporation into pre-40S ribosomal particles. This data indicate that missense mutations in DBA primarily affect the capacity of the protein to be incorporated into pre-ribosomes, thus blocking maturation of the pre-40S particles

The Value of Suction Drainage Fluid Culture during Aseptic and Septic Orthopedic Surgery: A Prospective Study of 901 Patients

There are no guidelines on the value of suction drainage fluid culture (SDC), and it is difficult to determine whether the organisms cultured from suction drainage fluid samples are pathogenic or simply contaminants. We performed 2989 cultures of suction drainage fluid samples obtained, during a 1-year period, from 901 patients who underwent aseptic or septic orthopedic surgery (946 operations). The culture results were analyzed to evaluate their ability to detect postoperative infection after aseptic operations or to detect either a persistent or new episode of sepsis in patients known to have infection. For aseptic operations, the sensitivity of SDC was 25%, the specificity was 99%, the positive predictive value was 25%, and the negative predictive value was 99%. For septic operations, the sensitivity of SDC was 81%, the specificity was 96%, the positive predictive value was 87%, and the negative predictive value was 94%. We conclude that, for aseptic orthopedic surgery, SDC is not useful in detecting postoperative infection. However, for septic orthopedic surgery, it is of clinical importanc

Nuclear Spin-Lattice Relaxation in One-Dimensional Heisenberg Ferrimagnets: Three-Magnon versus Raman Processes

Nuclear spin-lattice relaxation in one-dimensional Heisenberg ferrimagnets is studied by means of a modified spin-wave theory. We consider the second-order process, where a nuclear spin flip induces virtual spin waves which are then scattered thermally via the four-magnon exchange interaction, as well as the first-order process, where a nuclear spin directly interacts with spin waves via the hyperfine interaction. We point out a possibility of the three-magnon relaxation process predominating over the Raman one and suggest model experiments.Comment: to be published in J. Phys. Soc. Jpn. 73, No. 6 (2004

Virosaurus A Reference to Explore and Capture Virus Genetic Diversity.

The huge genetic diversity of circulating viruses is a challenge for diagnostic assays for emerging or rare viral diseases. High-throughput technology offers a new opportunity to explore the global virome of patients without preconception about the culpable pathogens. It requires a solid reference dataset to be accurate. Virosaurus has been designed to offer a non-biased, automatized and annotated database for clinical metagenomics studies and diagnosis. Raw viral sequences have been extracted from GenBank, and cleaned up to remove potentially erroneous sequences. Complete sequences have been identified for all genera infecting vertebrates, plants and other eukaryotes (insect, fungus, etc.). To facilitate the analysis of clinically relevant viruses, we have annotated all sequences with official and common virus names, acronym, genotypes, and genomic features (linear, circular, DNA, RNA, etc.). Sequences have been clustered to remove redundancy at 90% or 98% identity. The analysis of clustering results reveals the state of the virus genetic landscape knowledge. Because herpes and poxviruses were under-represented in complete genomes considering their potential diversity in nature, we used genes instead of complete genomes for those in Virosaurus