Optimització dels paràmetres de procés de l’electroerosió de micro-canals en acer inoxidable per aplicacions biomèdiques

El present projecte està enfocat en la mecanització de micro-canals, on la fabricació anivell micro s’entén per a mecanitzacions de menys de 1 mil•límetre, mitjançantl’electroerosió i s’emmarca dins el grup de recerca en enginyeria del producte procés iproducció (GREP) de la universitat de Girona. Avui en dia la biomedicina és un sectorque està creixent i representa una gran oportunitat per a aquest tipus de mecanitzat, jaque alguns productes són de mida micromètrica i es necessita una alternativa almecanitzat tradicional per tal d’abaratir costos, guanyar precisió i qualitat superficial.La mecanització de micro-canals, geometria utilitzada en aquest sector, de granprecisió i elevat acabat superficial són requisits necessaris per donar respostes a lesnecessitats d’aquest camp. L’acer inoxidable 316L és un material molt utilitzat enbiomedicina gràcies a la seva biocompatibilitat. Exemples de la seva aplicació podenser els implants, les pròtesis, utensilis mèdics, etc

Si3N4 single-crystal nanowires grown from silicon micro- and nanoparticles near the threshold of passive oxidation

A simple and most promising oxide-assisted catalyst-free method is used to prepare silicon nitride nanowires that give rise to high yield in a short time. After a brief analysis of the state of the art, we reveal the crucial role played by the oxygen partial pressure: when oxygen partial pressure is slightly below the threshold of passive oxidation, a high yield inhibiting the formation of any silica layer covering the nanowires occurs and thanks to the synthesis temperature one can control nanowire dimensions

Micro-ordinateurs de poche : du gadget à l'irremplaçable [Handheld computers: the gadget that became an invaluable tool]

Les ordinateurs de poche ont le potentiel de devenir un outil de travail indispensable pour le médecin praticien. De part une facilité d'utilisation toujours plus grande, un format ultra-portable, une grande capacité de stockage de l'information et de synchronisation à de multiples bases de données, ils permettent l'accès en tout temps et littéralement au lit du malade à une gamme complète de ressources médicales. Cet article se veut une lllustration des différentes possibilités d'utilisation de ces nouveaux outils, au travers de situations cliniques banales rencontrées par tout praticien.

Bone mineral density (BMD), micro-architecture estimation (TBS) and vertebral fracture assessment (VFA) extracted from a single DXA device in combination with clinical risk factors improve significantly the identification of women at high risk of fracture.

Osteoporosis (OP) is a systemic skeletal disease characterized by a low bone mineral density (BMD) and a micro-architectural (MA) deterioration. Clinical risk factors (CRF) are often used as a MA approximation. MA is yet evaluable in daily practice by the trabecular bone score (TBS) measure. TBS is very simple to obtain, by reanalyzing a lumbar DXA-scan. TBS has proven to have diagnosis and prognosis values, partially independent of CRF and BMD. The aim of the OsteoLaus cohort is to combine in daily practice the CRF and the information given by DXA (BMD, TBS and vertebral fracture assessment (VFA)) to better identify women at high fracture risk. The OsteoLaus cohort (1400 women 50 to 80 years living in Lausanne, Switzerland) started in 2010. This study is derived from the cohort COLAUS who started in Lausanne in 2003. The main goal of COLAUS is to obtain information on the epidemiology and genetic determinants of cardiovascular risk in 6700 men and women. CRF for OP, bone ultrasound of the heel, lumbar spine and hip BMD, VFA by DXA and MA evaluation by TBS are recorded in OsteoLaus. Preliminary results are reported. We included 631 women: mean age 67.4 ± 6.7 years, BMI 26.1 ± 4.6, mean lumbar spine BMD 0.943 ± 0.168 (T-score − 1.4 SD), and TBS 1.271 ± 0.103. As expected, correlation between BMD and site matched TBS is low (r2 = 0.16). Prevalence of VFx grade 2/3, major OP Fx and all OP Fx is 8.4%, 17.0% and 26.0% respectively. Age- and BMI-adjusted ORs (per SD decrease) are 1.8 (1.2-2.5), 1.6 (1.2-2.1), and 1.3 (1.1-1.6) for BMD for the different categories of fractures and 2.0 (1.4-3.0), 1.9 (1.4-2.5), and 1.4 (1.1-1.7) for TBS respectively. Only 32 to 37% of women with OP Fx have a BMD < − 2.5 SD or a TBS < 1.200. If we combine a BMD < − 2.5 SD or a TBS < 1.200, 54 to 60% of women with an osteoporotic Fx are identified. As in the already published studies, these preliminary results confirm the partial independence between BMD and TBS. More importantly, a combination of TBS subsequent to BMD increases significantly the identification of women with prevalent OP Fx which would have been misclassified by BMD alone. For the first time we are able to have complementary information about fracture (VFA), density (BMD), micro- and macro architecture (TBS and HAS) from a simple, low ionizing radiation and cheap device: DXA. Such complementary information is very useful for the patient in the daily practice and moreover will likely have an impact on cost effectiveness analysis.

Evaluating spine micro-architectural texture (via TBS) discriminates major osteoporotic fractures from controls both as well as and independent of site matched BMD: the Eastern European TBS study.

The aim of the study was to assess the clinical performance of the model combining areal bone mineral density (aBMD) at spine and microarchitecural texture (TBS) for the detection of the osteoporotic fracture. The Eastern European Study is a multicenter study (Serbia, Bulgaria, Romania and Ukraine) evaluating the role of TBS in routine clinical practice as a complement to aBMD. All scans were acquired on Hologic Discovery and GE Prodigy densitometers in a routine clinical manner. The additional clinical values of aBMD and TBS were analyzed using a two steps classification tree approach (aBMD followed by TBS tertiles) for all type of osteoporotic fracture (All-OP Fx). Sensitivity, specificity and accuracy of fracture detection as well as the Net Reclassification Index (NRI) were calculated. This study involves 1031 women subjects aged 45 and older recruited in east European countries. Clinical centers were cross-calibrated in terms of BMD and TBS. As expected, areal BMD (aBMD) at spine and TBS were only moderately correlated (r (2) = 0.19). Prevalence rate for All-OP Fx was 26 %. Subjects with fracture have significant lower TBS and aBMD than subjects without fracture (p < 0.01). TBS remains associated with the fracture even after adjustment for age and aBMD with an OR of 1.27 [1.07-1.51]. When using aBMD T-score of -2.5 and the lowest TBS tertile thresholds, both BMD and TBS were similar in terms of sensitivity (35 vs. 39 %), specificity (78 vs. 80 %) and accuracy (64 vs. 66 %). aBMD and TBS combination, induced a significant improvement in sensitivity (+28 %) and accuracy (+17 %) compared to aBMD alone whereas a moderate improvement was observed in terms of specificity (+9 %). The overall combination gain was 36 % as expressed using the NRI. aBMD and TBS combination decrease significantly the number of subjects needed to diagnose from 7 for aBMD alone to 2. In a multi-centre Eastern European cohort, we have shown that the use of TBS in addition to the aBMD permit to reclassified correctly more than one-third of the overall subjects. Furthermore, the number of subjects needed to diagnose fell to 2 subjects. Economical studies have to be performed to evaluate the gain induced by the use of TBS for the healthcare system.

Determinants of science-based cooperation: evidence in a sample of small and micro firms

We study the determining factors of cience-based cooperation in the case of small and micro firms. In this research, we propose an analytical framework based on the resource-based view of the firm and we identify a set of organisational characteristics, which we classify as internal, external and structural factors. Each factor can be linked to at least one reason, from the firm¿s point of view, to cooperate with universities and public research centres. Each reason can, in turn, be used as an indicator of a firm¿s organisational needs or organisational capacities. In order to validate the theoretical model, we estimate a logistic regression that models the propensity to participate in science-based cooperation activities within a sample of 285 small and micro firms located in Barcelona. The results show the key role played by the absorptive capacity of new and small companies.

Diradicals acting through diamagnetic phenylene vinylene bridges: Raman spectroscopy as a probe to characterize spin delocalization

We present a complete Raman spectroscopic study in two structurally well-defined diradical species of different lengths incorporating oligo p-phenylene vinylene bridges between two polychlorinated triphenylmethyl radical units, a disposition that allows sizeable conjugation between the two radicals through and with the bridge. The spectroscopic data are interpreted and supported by quantum chemical calculations. We focus the attention on the Raman frequency changes, interpretable in terms of: (i) bridge length (conjugation length); (ii) bridge conformational structure; and (iii) electronic coupling between the terminal radical units with the bridge and through the bridge, which could delineate through-bond spin polarization, or spin delocalization. These items are addressed by using the"oligomer approach" in conjunction with pressure and temperature dependent Raman spectroscopic data. In summary, we have attempted to translate the well-known strategy to study the electron (charge) structure of π−conjugated molecules by Raman spectroscopy to the case of electron (spin) interactions via the spin delocalization mechanism.

The micro-architecture estimation by TBS discriminate women with and without osteoporotic fracture independently of age, BMI and BMD: The Osteo-Mobile Vaud cohort study.

Introduction: « Osteo-Mobile Vaud » is a mobile osteoporosis (OP) screening program. The women > 60 years living in the region Vaud will be offered OP screening with new equipment installed in a bus. The main goal is to evaluate the fracture risk with the combination of clinical risk factors (CRF) and informations extracted by a single DXA: bone mineral density (BMD), vertebral fracture assessment (VFA), and micro-architecture (MA) evaluation. MA is yet evaluable in daily practice by the Trabecular Bone Score (TBS) measure. TBS is a novel grey-level texture measurement reflecting bone MA based on the use of experimental variograms of 2D projection images. TBS is very simple to obtain, by reanalyzing a lumbar DXA-scan. TBS has proven to have diagnosis and prognosis value, partially independent of CRF and BMD. A 55-years follow- up is planned. Method: The Osteo-Mobile Vaud cohort (1500 women, > 60 years, living in the region Vaud) started in July 2010. CRF for OP, lumbar spine and hip BMD, VFA by DXA and MA evaluation by TBS are recorded. Preliminary results are reported. Results: In July 31th, we evaluated 510 women: mean age 67 years, BMI 26 kg/m². 72 women had one or more fragility fractures, 39 had vertebral fracture (VFx) grade 2/3. TBS decreases with age (-0.005 / year, p<0.001), and with BMI (-0.011 per kg/m², p<0.001). Correlation between BMD and site matched TBS is low (r=0.4, p<0.001). For the lowest T-score BMD, odds ratio (OR, 95% CI) for VFx grade 2/3 and clinical OP Fx are 1.8 (1.1-2.9) and 2.3 (1.5-3.4). For TBS, age-, BMI- and BMD adjusted ORs (per SD decrease) for VFx grade 2/3 and clinical OP Fx are 1.9 (1.2-3.0) and 1.8 (1.2-2.7). The TBS added value was independent of lumbar spine BMD or the lowest T-score (femoral neck, total hip or lumbar spine). Conclusion: As in the already published studies, these preliminary results confirm the partial independence between BMD and TBS. More importantly, a combination of TBS and BMD may increase significantly the identification of women with prevalent OP Fx. For the first time we are able to have complementary information about fracture (VFA), density (BMD), and micro-architecture (TBS) from a simple, low ionizing radiation and cheap device: DXA. The value of such informations in a screening program will be evaluated.

Evaluating the Trabecular Micro-Bypass Stent Combined with Phacoemulsification Compared to Phacoemulsification Alone.

Aim: The aim of this study was to assess the effect of iStent (trabecular micro-bypass stent) implantation in combination with phacoemulsification on IOP and glaucoma medications and to compare this to the outcome of phacoemulsification alone. Patients and Methods: A retrospective consecutive comparative review was undertaken. 131 eyes with ocular hypertension and medically controlled glaucoma underwent phacoemulsification alone (n = 78 group I) or combined with gonioscopic-guided implantation of one iStent (n = 31, group II) or two iStents (n = 22, group III). Patients were assessed at postoperative weeks 1, 3 and 6, and months 3 and 6. Pre- and post-operative measures included visual acuity, IOP and glaucoma medications. Results: Post-operatively at 6 months, mean IOP decreased from 16.3 mmHg to 14.2 mmHg in group I (p < 0.01), from 16.7 mmHg to 15.1 mmHg in group II (p < 0.16) and from 17.0 to 13.8 in group III (p = 0.05). Mean glaucoma medication decreased from 1.9 to 1.6 in group I (8 %, p = 0.12), from 2.5 to 0.8 in group II (27 %, p = 0.04), and from 2.1 to 1.0 in group III (45 %, p < 0.01). Conclusions: iStent implantation resulted in similar IOP reduction to phacoemulsification alone but achieved a significantly greater reduction in glaucoma medications. This may improve compliance and quality of life, and reduce health care costs in patients with early to moderate glaucoma.