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1.
Acta Orthop Belg ; 89(4): 625-633, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38205752

RESUMEN

The aim of the study was to evaluate a modified direct lateral approach for total hip arthroplasty in terms of clinical and functional outcomes, rate of complications and hospitalization. We retrospectively reviewed the data of 526 patients with THA operated in our department between January 2017 and December 2021. Clinical examination, functional outcome and radiographic evaluation were performed during follow-up. Patients were evaluated at the following time points: preoperatively and postoperatively at 3 days, 6 weeks, 12 weeks and 1 year and we registered surgery related data, complications, Visual Analogue Scale pain score, Harris Hip Score, the Western Ontario McMaster Osteoarthritis Index. Low intraoperative blood loss, short operation time, short hospitalization, early mobilization of the patient and good range of motion imposed the modified direct lateral approach as a valuable procedure for the patients with THA. VAS score evaluated at 3 days and 6 weeks indicated a very good overall postoperative experience. The HHS and Womac scores were evaluated at 6 weeks, 12 weeks and 1 year and showed excellent results. Trendelenburg gait and abductor weakness, traditionally related with direct lateral approach, were not significant statistically and complete reversible. We registered a very low complication rates with good functional outcome. The modified direct lateral approach can lead to superior outcomes, improved quality of life, with reduced intra and postoperative complications rate.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Humanos , Calidad de Vida , Estudios Retrospectivos , Pérdida de Sangre Quirúrgica , Marcha
2.
Phys Rev Lett ; 128(11): 112503, 2022 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-35363014

RESUMEN

We have measured the 3d→2p transition x rays of kaonic ^{3}He and ^{4}He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be 6224.5±0.4(stat)±0.2(syst) eV and 6463.7±0.3(stat)±0.1(syst) eV, and widths to be 2.5±1.0(stat)±0.4(syst) eV and 1.0±0.6(stat)±0.3(stat) eV, for kaonic ^{3}He and ^{4}He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential models.

3.
Acta Endocrinol (Buchar) ; 16(4): 437-442, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-34084234

RESUMEN

BACKGROUND: If not diagnosed at birth, congenital hypothyroidism (CH) can cause deleterious, irreversible neurodevelopmental sequels. The importance of thyroid newborn screening (NBS) is therefore well established. OBJECTIVE: To evaluate the efficacy of NBS for CH in North-East Romania. METHODS: Retrospective, descriptive study involving 271662 newborns screened between 2010 and 2019 for CH and phenylketonuria in maternities from six Romanian North-Eastern counties by measuring neonatal TSH (neoTSH) in the whole blood extracted from the heel between days 3 and 5 after birth. Values found higher than a cut-off level of 10 mIU/L were followed by serum evaluation of TSH and fT4 for the confirmation of CH. Thyroid ultrasound was further performed at children found with CH. RESULTS: NeoTSH was found elevated in 417 newborns, but CH was subsequently confirmed in only 57 cases (1/4766 newborns). Mean age at the time when diagnosis was communicated was of 37.2 ± 15 days (between 9 and 157 days). Mean age when therapy was started was of 44.2 ± 17.9 days (between 13 and 160 days) with a mean delay of one week from diagnosis (between 0 and 62 days). Thyroid ultrasound revealed athyreosis in only 3 cases, atrophic thyroid gland in other 10 cases, whereas the thyroid was described as present in the remnant 44 cases. The number of first year follow-up visits greatly varied from 0 to 5, with an average of 2. CONCLUSIONS: NBS allowed rapid diagnosis of CH in North East Romania. The communication of diagnosis to families and therapy onset were however often delayed. Diagnosis and therapy onset before the age of two weeks, as well as a tighter follow-up should be assured by the healthcare system. Etiological diagnosis should be more accurate, for a better prognosis of disease severity, as well as the possibility of genetic advice in selected cases.

4.
Acta Endocrinol (Buchar) ; 13(3): 308-313, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-31149192

RESUMEN

CONTEXT AND OBJECTIVE: The new insights in the pathogenesis of osteoarthritis (OA) reveal the implications of adipocytokines. This study aims to analyze the correlations between the serum value of adiponectin and the clinical rehabilitation effects in patients diagnosed with knee OA, admitted and treated in the complex balneal resort of Techirghiol lake. SUBJECTS AND METHODS: The prospective randomized clinical study included 23 patients in the study group, diagnosed with knee OA according to ACR criteria, and a matching control group of 23 subjects. Serum level of adiponectin (using ELISA technique), uric acid, triglycerides, cholesterol, HDL-cholesterol and clinical response using a visual analog scale (VAS) were evaluated in all patients on their admission day and after 10 days of balneal treatment. Control group benefited from the same procedures except for cold mud therapy and mineral water baths. RESULTS: Plasma adiponectin levels (23.73±6.44 ng/dL) were statistically higher (p<0.05) in the study group compared to the control group (18.15±6.49 ng/dL). The mean VAS in both groups was decreased (p<0.005) compared to the initial moment. CONCLUSIONS: Cold peloidotherapy combined with physical therapy and balneal factors induces serum adiponectin elevation and improves knee pain in OA. Therapeutic properties of Techirghiol mud still need further research.

5.
Nucl Phys A ; 914(100): 305-309, 2013 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-24068854

RESUMEN

The kaonic 3He and 4He [Formula: see text] transitions in gaseous targets were observed by the SIDDHARTA experiment. The X-ray energies of these transitions were measured with large-area silicon-drift detectors using the timing information of the [Formula: see text] pairs produced by the DAΦNE [Formula: see text] collider. The strong-interaction shifts and widths both of the kaonic 3He and 4He 2p states were determined, which are much smaller than the results obtained by the previous experiments. The "kaonic helium puzzle" (a discrepancy between theory and experiment) was now resolved.

6.
Nucl Phys A ; 907(100): 69-77, 2013 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-23805024

RESUMEN

The study of the [Formula: see text] system at very low energies plays a key role for the understanding of the strong interaction between hadrons in the strangeness sector. At the DAΦNE electron-positron collider of Laboratori Nazionali di Frascati we studied kaonic atoms with [Formula: see text] and [Formula: see text], taking advantage of the low-energy charged kaons from Φ-mesons decaying nearly at rest. The SIDDHARTA experiment used X-ray spectroscopy of the kaonic atoms to determine the transition yields and the strong interaction induced shift and width of the lowest experimentally accessible level (1s for H and D and 2p for He). Shift and width are connected to the real and imaginary part of the scattering length. To disentangle the isospin dependent scattering lengths of the antikaon-nucleon interaction, measurements of [Formula: see text] and of [Formula: see text] are needed. We report here on an exploratory deuterium measurement, from which a limit for the yield of the K-series transitions was derived: [Formula: see text] and [Formula: see text] (CL 90%). Also, the upcoming SIDDHARTA-2 kaonic deuterium experiment is introduced.

7.
Phys Lett B ; 714(1): 40-43, 2012 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-22876000

RESUMEN

The kaonic (3)He and (4)He X-rays emitted in the [Formula: see text] transitions were measured in the SIDDHARTA experiment. The widths of the kaonic (3)He and (4)He 2p states were determined to be [Formula: see text], and [Formula: see text], respectively. Both results are consistent with the theoretical predictions. The width of kaonic (4)He is much smaller than the value of [Formula: see text] determined by the experiments performed in the 70's and 80's, while the width of kaonic (3)He was determined for the first time.

8.
Phys Lett B ; 697(3-2): 199-202, 2011 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-21633519

RESUMEN

The first observation of the kaonic (3)He 3d→2p transition was made, using slow K- mesons stopped in a gaseous (3)He target. The kaonic atom X-rays were detected with large-area silicon drift detectors using the timing information of the K+K- pairs of ϕ-meson decays produced by the DAΦNE e+e- collider. The strong interaction shift of the kaonic (3)He 2p state was determined to be -2±2(stat)±4(syst) eV.

9.
Microsc Res Tech ; 71(3): 236-47, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18041781

RESUMEN

Chitosan-based polymers have been extensively studied for biomedical applications. Recently, liquid solutions of chitosan in a glycerol phosphate buffer (chitosan-GP) with physiological pH and osmolality were mixed with autologous blood to form hybrid chitosan-GP/blood implants that improved the repair of articular cartilage lesions in a large animal model. The mixture of chitosan-GP and blood forms a viscous liquid, which solidifies in minutes via normal blood coagulation as well as chitosan-mediated mechanisms. Here we have examined the ultrastructure of these chitosan-GP/blood clots as well as regular blood clots and chitosan-GP gels, the latter produced by heating. Both unfixed and fixed samples of chitosan-GP/blood clots, regular blood clots, and chitosan-GP gels were investigated by environmental scanning electron microscopy (ESEM) in conjunction with energy dispersive X-ray spectrometry (EDS), the former permitting direct observation of the ultrastructure in hydrated conditions simulating the natural state. By examination of unfixed specimens using ESEM we found that chitosan formed a network structure in both chitosan-GP gels and chitosan-GP/blood clots; however this structure was altered by aldehyde fixation to produce artifactual aggregates of chitosan microparticles. We were also able to identify chitosan in chitosan-GP/blood clots by washing samples in low concentration NaCl solutions followed by local EDS analyses to identify excess chloride versus sodium, and thus presence of cationic chitosan in analyzed features. Additional results indicated that the majority of glycerol phosphate diffuses freely from chitosan-GP gels (by EDS of phosphorus) and that hyperosmotic paraformaldehyde-based fixatives (i.e. 4% w/v) significantly disturb erythrocyte morphology in fixed whole blood clots.


Asunto(s)
Materiales Biocompatibles , Coagulación Sanguínea/fisiología , Quitosano , Eritrocitos/ultraestructura , Glicerofosfatos , Microscopía Electrónica de Rastreo/métodos , Aldehídos/química , Quitosano/química , Glicerofosfatos/química , Humanos , Microscopía Electrónica de Rastreo/instrumentación , Espectrometría por Rayos X , Fijación del Tejido/métodos
10.
Eur Phys J C Part Fields ; 78(4): 319, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29706795

RESUMEN

The VIolation of Pauli exclusion principle -2 experiment, or VIP-2 experiment, at the Laboratori Nazionali del Gran Sasso searches for X-rays from copper atomic transitions that are prohibited by the Pauli exclusion principle. Candidate direct violation events come from the transition of a 2p electron to the ground state that is already occupied by two electrons. From the first data taking campaign in 2016 of VIP-2 experiment, we determined a best upper limit of [Formula: see text] for the probability that such a violation exists. Significant improvement in the control of the experimental systematics was also achieved, although not explicitly reflected in the improved upper limit. By introducing a simultaneous spectral fit of the signal and background data in the analysis, we succeeded in taking into account systematic errors that could not be evaluated previously in this type of measurements.

11.
J Low Temp Phys ; 184(3-4)2016.
Artículo en Inglés | MEDLINE | ID: mdl-39473821

RESUMEN

A performance evaluation of superconducting transition-edge sensors (TESs) in the environment of a pion beam line at a particle accelerator is presented. Averaged across the 209 functioning sensors in the array, the achieved energy resolution is 5.2 eV FWHM at Co K α (6.9 keV) when the pion beam is off and 7.3 eV at a beam rate of 1.45 MHz. Absolute energy uncertainty of ±0.04 eV is demonstrated for Fe K α (6.4 keV) with in-situ energy calibration obtained from other nearby known X-ray lines. To achieve this small uncertainty, it is essential to consider the non-Gaussian energy response of the TESs and thermal cross-talk pile-up effects due to charged particle hits in the silicon substrate of the TES array.

12.
Biomaterials ; 25(13): 2539-45, 2004 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-14751739

RESUMEN

We extended for the first time pulsed laser ablation to the deposition of octacalcium phosphate Ca8H2(PO4)6.5H2O (OCP) thin films. The depositions were performed with a pulsed UV laser source (lambda=248 nm, tau> or =20 ns) in a flux of hot water vapors. The targets were sintered from crystalline OCP powder and the laser ablation fluence was set at values of 1.5-2 J/cm2. During depositions the collectors, Si or Ti substrates, were maintained at a constant temperature within the range 20-200 degrees C. The resulting structures were submitted to heat treatment in hot water vapors for up to 6 h. The best results were obtained at a substrate temperature of 150 degrees C during both deposition and post-deposition treatment. High-resolution electron microscopy and XRD at grazing incidence indicated that the coatings obtained were made of nanocrystalline OCP. Cross-section TEM investigations showed that the coatings contained droplets stacked on Ti substrates as well as distributed across the entire thickness of the arborescence-like structure layers. The results of WST-1 assay, cell adherence, DNA replication, and caspase-1 activity confirmed the good biocompatibility of the coatings.


Asunto(s)
Materiales Biocompatibles , Fosfatos de Calcio/química , Animales , Apoptosis , Adhesión Celular , División Celular , Línea Celular , Replicación del ADN , Humanos , Rayos Láser , Ratones , Nanotecnología , Difracción de Rayos X
13.
J Biomed Mater Res A ; 71(2): 353-8, 2004 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-15372467

RESUMEN

Mn(2+)-doped carbonated hydroxyapatite (Mn-CHA) thin films were obtained by pulsed laser deposition on Ti substrates. The results of the performed complementary diagnostic techniques, X-ray diffraction, infrared spectroscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy investigations indicate that the films are crystalline with a Ca/P ratio of about 1.64-1.66. The optimum conditions, when nearly stoichiometric crystalline thin films were deposited, were found to be 10 Pa oxygen pressure, 400 degrees C substrate temperature, and postdeposition heat treatment in water vapors at the same substrate temperature. The films were seeded with L929 fibroblast and hFOB1.19 osteoblast cells and subjected to in vitro tests. Both fibroblast and osteoblast cells have a good adherence on the Mn-CHA film and on the Ti or polystyrene references. Proliferation and viability tests showed that osteoblast cells growth on Mn-CHA-coated Ti was enhanced as compared to uncoated pure Ti surfaces. Caspase-1 activity was not affected significantly by the material, showing that Mn-CHA does not induce apoptosis of cultured cells. These results demonstrate that Mn-CHA films on Ti should provoke a faster osteointegration of the coated implants as compared to pure Ti. (c) 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 353-358, 2004.


Asunto(s)
Materiales Biocompatibles/síntesis química , Durapatita/química , Rayos Láser , Manganeso/química , Animales , Materiales Biocompatibles/química , Adhesión Celular/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , ADN/biosíntesis , Durapatita/síntesis química , Ratones , Microscopía Electrónica de Rastreo , Difracción de Rayos X
14.
Oftalmologia ; 40(2): 120-4, 1996.
Artículo en Ro | MEDLINE | ID: mdl-8717078

RESUMEN

One child four and half years old remains with a divergent deviation by forty-five degree with absence of adduction, after an operation of convergent strabismus at the left eye. Considering that is about by one postoperatorial paralytic strabismus, computer tomography praises the right intern muscle retracted at the back of orbit, but it doesn't adheres at the eyeball. It considers that the divergent strabismus was caused by the slide of postoperatorial muscle. Looking middle line of the muscle, parallel with the middle wall of the orbit, it praises the right intern muscle retracted and after the excision of the granulation tissue all round, displays the muscle with its normal lenght. It cuts 3.5 milimeters from this muscle and it practices the retroposition of the extern right muscle with 7 milimeters. It obtains postoperatorial orthophoria. It talks about possibility of lossen of a right muscle in orbit intra- and post-operatorial and the measures that are imposed in these situations.


Asunto(s)
Complicaciones Intraoperatorias/diagnóstico , Músculos Oculomotores/lesiones , Oftalmoplejía/diagnóstico , Complicaciones Posoperatorias/diagnóstico , Preescolar , Exotropía/complicaciones , Exotropía/diagnóstico , Exotropía/cirugía , Humanos , Complicaciones Intraoperatorias/etiología , Masculino , Músculos Oculomotores/cirugía , Oftalmoplejía/etiología , Órbita , Complicaciones Posoperatorias/etiología
15.
Int. j. morphol ; 35(4): 1553-1559, Dec. 2017. tab, graf
Artículo en Inglés | LILACS | ID: biblio-893168

RESUMEN

SUMMARY: This study represents a morphometric assessment of the anterior segment of the lumbar spine, focused on the vertebral body - intervertebral disk assembly, calculating some specific indicators and then completing direct morphometry data with the data resulting from the imaging interpretation and subsequently correlating the same to map an anatomic-imaging model. The study was carried out with anatomic items from personal archive and images obtained from Computer Tomography (CT) and Magnetic Resonance Imaging (MRI) assessment. The morphometric assessment was carried out for intervertebral disks, the disk height in the anterior and posterior sections and correlated with the disk angle degree. Direct morphometric data was compared and correlated with the data resulting from the imaging interpretation. Direct morphometric assessment was carried out for 11 vertebral blocks; the vertebral blocks were sectioned and turned into 22 vertebral semi-blocks allowing easy access to absolutely all dimensional values pursued, including the ones covered by the posterior arc. The assessment of imaging data was made with CT, CT 3D and MRI investigations from the 120 subjects in the study. The disk sizes were assessed by direct measurements on the anatomic items and directly measured by means of the software for modern imaging examination. In case of significant differences between the vertebral bodies, the calculation of disk sizes was made indirectly, on grounds of the geometric interpretation of the vertebral body face sizes. The vertebral body / intervertebral disk (IVD) assembly represents a dynamic structure, permanently subject to changes and adaptation, IVD being capable of incurring changes for the entire life time, including growth changes; the growth, however, is not lineal, but a succession of thickening and getting thinner, in full concordance with the structural stresses and changes occurring inside.


RESUMEN: El estudio representa una evaluación morfométrica del segmento anterior de la columna lumbar, centrado en el conjunto del cuerpo vertebral - disco intervertebral, calculando algunos indicadores específicos y completando los datos morfométricos directos. El objetivo del trabajo fue mapear un modelo de imagen anatómica con los datos de la interpretación de la imagen, posteriormente correlacionando los datos. El estudio se llevó a cabo con artículos anatómicos de archivos personales y de las imágenes obtenidas de tomografía computarizada (TC) y resonancia magnética (RM) de evaluación. La evaluación morfométrica se realizó en los discos intervertebrales, la altura del disco en las secciones anterior y posterior y se correlacionó con el grado del ángulo del disco. Se compararon los datos morfométricos directos y se correlacionaron con los datos resultantes de la interpretación de la imagen. Se realizó una evaluación morfométrica directa de 11 bloques vertebrales; Los bloques vertebrales se seccionaron y se convirtieron en 22 semibloques vertebrales permitiendo el fácil acceso a todos los valores dimensionales, incluyendo aquellos cubiertos por el arco posterior. La evaluación de los datos de imagen se realizó en 120 sujetos con CT, CT 3D y MRI. Los tamaños de los discos se evaluaron mediante medidas directas de los elementos anatómicos y se midieron con el software para la examinación de imágenes. En caso de diferencias significativas entre los cuerpos vertebrales, el cálculo de los tamaños de los discos se realizó indirectamente, debido a la interpretación geométrica de los tamaños de la cara del cuerpo vertebral. El conjunto cuerpo vertebral / disco intervertebral (CVDV) representa una estructura dinámica, permanentemente sujeta a transformaciones y adaptación, siendo (CVDV) capaz de incurrir en cambios durante toda la vida, incluyendo aquellos relacionados con crecimiento. El crecimiento, sin embargo, no es lineal, sino una sucesión de engrosamiento y adelgazamiento, en plena concordancia con las tensiones estructurales y los cambios que se producen en su interior.


Asunto(s)
Humanos , Disco Intervertebral/anatomía & histología , Disco Intervertebral/diagnóstico por imagen , Vértebras Lumbares/anatomía & histología , Vértebras Lumbares/diagnóstico por imagen , Imagenología Tridimensional , Imagen por Resonancia Magnética , Tomografía Computarizada por Rayos X
17.
Phys Rev Lett ; 94(21): 212302, 2005 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-16090312

RESUMEN

The DEAR (DAPhiNE exotic atom research) experiment measured the energy of x rays emitted in the transitions to the ground state of kaonic hydrogen. The measured values for the shift epsilon and the width Gamma of the 1s state due to the K(-)p strong interaction are epsilon(1s)=-193 +/- 37 (stat) +/- 6 (syst) eV and Gamma(1s)=249 +/- 111 (stat) +/- 30 (syst) eV, the most precise values yet obtained. The pattern of the kaonic hydrogen K-series lines, K(alpha), K(beta), and K(gamma), was disentangled for the first time.

18.
Arch Tierernahr ; 36(9): 803-25, 1986 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-3099732

RESUMEN

The efficiency of utilization of feed energy as digestible, metabolizable and net energy is similar in pregnant and lactating sows irrespective of the stage of these physiological conditions. This efficiency with the value of about 71% resembles the one found in the growing and fattening pigs, which enables us to use, for this category of animals, the same system offered evaluation and of the energy requirements based on fat nutritive units. The maintenance energy requirement expressed in ME varies from 467 kJ/kg 0.75 in pregnant sows to 512 kJ/kg 0.75 in lactating sows, for the suckling piglets having intermediary value of 498 kJ/kg 0.75. The efficiency of utilization of diets protein for maintenance and for synthesis is also similar for these categories of pigs, varying from 71% in lactating sows to 75-76% in pregnant sows. In suckling piglets we had recorded an efficiency of DCP utilization which varies parabolically with size of the ingesta and therefore with that of weight gain. The DCP maintenance requirement expressed in g N dig./kg 0.75 varies within narrow limits between 0.345 g N in suckling piglets 0.380 g N in pregnant sows; In lactating sows we have detected an intermediary value of 0.355 g N. Based on these experimental data and also using recent experimental results obtained by Schiemann and Beyer (1984) regarding the energy and N content of the foetuses, of the organs of reproductions and of milk, we could calculate the energy and protein requirements. These requirements when compared with the values used in our country show us higher values of energy in pregnant and lactating sows and lower values of protein for the same categories, including the piglets, where we have also found lower values for the energy too.


Asunto(s)
Proteínas en la Dieta/metabolismo , Ingestión de Energía , Lactancia/metabolismo , Preñez/metabolismo , Porcinos/metabolismo , Animales , Peso Corporal , Cistina/metabolismo , Femenino , Tamaño de la Camada , Lisina/metabolismo , Metionina/metabolismo , Nitrógeno/metabolismo , Necesidades Nutricionales , Embarazo
19.
Arch Tierernahr ; 30(4): 351-61, 1980 Apr.
Artículo en Alemán | MEDLINE | ID: mdl-7447696

RESUMEN

In a total of 134 experiments concerning the general metabolism of growing pigs in a live weight range of 10 to 30 kg the nutrient and energy retention were investigated under the conditions of ad libitum feeding and feeding on the maintenance level including two fasting days, providing four rations with different protein concentration (16 to 22%). N-utilisation was ascertained as 81.2 +/- 4.2% and N-maintenance requirement as 0.199 g N per kg live weight0.75. The utilisation level of metabolisable energy (ME) was independent of the protein level but dependent on the method of calculation. The utilisation value of 73.8 +/- 3.0% was calculated as the best adaptation to the balance experiments altogether. It corresponds to the energy maintenance requirement of 434 kJ ME/kg live weight0.75. The standards of the energy requirement of growing pigs in the live weight range of 10 to 50 kg are derived from this results and earlier experiments and put up for discussion.


Asunto(s)
Proteínas en la Dieta/farmacología , Metabolismo Energético , Nitrógeno/metabolismo , Porcinos/metabolismo , Alimentación Animal , Animales , Crecimiento , Masculino , Necesidades Nutricionales
20.
J Mater Sci Mater Med ; 13(12): 1167-73, 2002 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-15348661

RESUMEN

Calcium orthophosphates (CaP) and hydroxyapatite (HA) were intensively studied in order to design and develop a new generation of bioactive and osteoconductive bone prostheses. The main drawback now in the CaP and HA thin films processing persists in their poor mechanical characteristics, namely hardness, tensile and cohesive strength, and adherence to the metallic substrate. We report here a critical comparison between the microstructure and mechanical properties of HA and CaP thin films grown by two methods. The films were grown by KrF* pulsed laser deposition (PLD) or KrF* pulsed laser deposition assisted by in situ ultraviolet radiation emitted by a low pressure Hg lamp (UV-assisted PLD). The PLD films were deposited at room temperature, in vacuum on Ti-5Al-2.5Fe alloy substrate previously coated with a TiN buffer layer. After deposition the films were annealed in ambient air at 500-600 degrees C. The UV-assisted PLD films were grown in (10(-2)-10(-1) Pa) oxygen directly on Ti-5Al-2.5Fe substrates heated at 500-600 degrees C. The films grown by classical PLD are crystalline and stoichiometric. The films grown by UV-assisted PLD were crystalline and exhibit the best mechanical characteristics with values of hardness and Young modulus of 6-7 and 150-170 GPa, respectively, which are unusually high for the calcium phosphate ceramics. To the difference of PLD films, in the case of UV-assisted PLD, the GIXRD spectra show the decomposition of HA in Ca(2)P(2)O(7), Ca(2)P(2)O(9) and CaO. The UV lamp radiation enhanced the gas reactivity and atoms mobility during processing, increasing the tensile strength of the film, while the HA structure was destroyed.

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