Chine : spécialisation internationale et rattrapage technologique

Les annees quatre-vingt dix ont vu la montee en puissance de la Chine sur differents marches mondiaux de produits, y compris ceux a forte intensite technologique. La Chine a pu prendre position dans ces secteurs, ou la demande internationale est forte et les gains de productivite importants, en se specialisant dans les activites d'assemblage, qui sont intensifs en travail et ou elle a un avantage comparatif.Chine; Asie; specialisation; division internationale des processus productifs; transferts de technologie

Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHA–PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA–PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules

Hydroxyapatite reinforced chitosan and polyester blends for biomedical applications

Hydroxyapatite, chitosan, and aliphatic polyester were compounded using a twin-screw extruder. The polyesters include poly(e-caprolactone) (PCL), poly(lactic acid) , poly(butylene succinate) (PBS), and poly(butylene terephthalate adipate). The mass fraction of chitosan ranged from 17.5 to 45%, while that of HA ranged from 10 to 30%. These blends were injection molded and evaluated for thermal, morphological, and mechanical properties. The addition of hydroxyapatite decreased the crystallinity in chitosan/PBS blends, while in blends containing chitosan/PCL, the crystallinity increased. Addition of hydroxyapatite significantly decreased the tensile strength and elongation of polyester/ hydroxyapatite composites as well as chitosan/polyester/ hydroxyapatite composites with elongations undergoing decreases over an order of magnitude. The tensile strength of the composite was dictated by the adhesion of HA to the chitosan/ polyester matrix. The tensile strength of composites containing hydroxyapatite could be predicted using the Nicolai and Narkis equation for weak filler adhesion (K 1.21). Tensile-fractured and cryogenically-fractured surface indicates extensive debonding of hydroxyapatite crystals from the matrix, indicating weak adhesion. The adhesion of hydroxyapatite was higher for pure polyester than those containing chitosan and polyester. The modulus of the composites registered modest increase. The two main diffraction peaks observed using WAXS are unaffected by the amount of chitosan or hydroxyapatite

Crystallization Study and Comparative in Vitro–in Vivo Hydrolysis of PLA Reinforcement Ligament

In the present work, the crystallization behavior and in vitro–in vivo hydrolysis rates of PLA absorbable reinforcement ligaments used in orthopaedics for the repair and reinforcement of articulation instabilities were studied. Tensile strength tests showed that this reinforcement ligament has similar mechanical properties to Fascia Latta, which is an allograft sourced from the ilio-tibial band of the human body. The PLA reinforcement ligament is a semicrystalline material with a glass transition temperature around 61 °C and a melting point of ~178 °C. Dynamic crystallization revealed that, although the crystallization rates of the material are slow, they are faster than the often-reported PLA crystallization rates. Mass loss and molecular weight reduction measurements showed that in vitro hydrolysis at 50 °C initially takes place at a slow rate, which gets progressively higher after 30–40 days. As found from SEM micrographs, deterioration of the PLA fibers begins during this time. Furthermore, as found from in vivo hydrolysis in the human body, the PLA reinforcement ligament is fully biocompatible and after 6 months of implantation is completely covered with flesh. However, the observed hydrolysis rate from in vivo studies was slow due to high molecular weight and degree of crystallinity

Thermally-activated shape memory effect on biodegradable nanocomposites based on PLA/PCL blend reinforced with hydroxyapatite

[EN] In this work, the effect of the addition of different amount of nanosized hydroxyapatite (nHA) on the shape memory behavior of blends based on poly (lactic acid) (PLA) and poly (epsilon-caprolactone) (PCL) has been studied. In particular PLA/PCL blend with 70 wt % PLA has been reinforced with 0.5, 1 and 3 wt % nHA. Moreover, the relationship between the morphology and the final properties of the nanocomposites has been investigated by field emission scanning electron microscopy, confocal Raman spectroscopy and atomic force microscopy. In particular, PeakForce has been used to study quantitative nanomechanical properties of the multifunctional materials leading to conclusion that nHA increase the phase separation between PLA and PCL as well as act as reinforcements for the PCL-rich phase of the nanocomposites. Furthermore, excellent thermally-activated shape memory response has been obtained for all the nanocomposites at 55 degrees C. Finally, the disintegration under composting conditions at laboratory scale level was studied in order to confirm the biodegradable character of these nanocomposites. Indeed, these materials are able to be used for biomedical issues as well as for packaging applications where both thermally-activated shape memory effect and biodegradability are requested.Authors thank the Spanish Ministry of Economy, Industry and Competitiveness, MINEICO, (MAT2017-88123-P) and the Regional Government of Madrid (S2013/MIT-2862) for the economic support. M.P.A. and L.P. acknowledge the Juan de la Cierva (FJCI-2014-20630) and Ramon y Cajal (RYC-2014-15595) contracts from the MINEICO, respectively. The authors also thanks CSIC for the I-Link project (I-Link1149).Peponi, L.; Sessini, V.; Arrieta, MP.; Navarro-Baena, I.; Sonseca Olalla, Á.; Dominici, F.; Giménez Torres, E.... (2018). Thermally-activated shape memory effect on biodegradable nanocomposites based on PLA/PCL blend reinforced with hydroxyapatite. Polymer Degradation and Stability. 151:36-51. https://doi.org/10.1016/j.polymdegradstab.2018.02.019S365115

Tvåspråkighet i förskolan

The purpose of my study is to examine how four teachers in a pre school believe they relates to and reasons about bilingualism. To be able to realize thisstudy, i proposed three issue following: How do the teachers in kindergarten relate to bilingualism? How do teachers in preschool reason around the work of bilingual children? What do teachers think about the educational environment in relation to language development

Markkina- ja kehitystutkimus

Tämä työ sisältää markkina–ja kehitystutkimuksen, lohjalaiselle logistiikkayritykselle. Lohjan KTK Osuuskunta on tehnyt nykyisen toimitusjohtajan kanssa vuodesta 2006 tähän päivään asti strategisia linjauksia toiminnan kehittämiseksi. Tästä johtuen Lohjan KTK haluaa pitää kehityksensä katkeamattomana ketjuna ja tutkii olemassa olevia ja mahdollisia markkinoita ja kehittää toimintaympäristöään markkinoiden ja asiakkaiden arvojen mukaisesti. Työ sisältää asiakas- ja jäsenkyselyn sekä markkinointiliitteen logistiikan nykytilanteesta sekä Lohjan KTK:n kustannustehokkaista logistisista palveluista. Työssä haastateltiin Lohjan KTK:n merkittäviä asiakkaita sekä lohjalaista kansanedustajaa. Työn tavoitteena oli saada realistinen kuvaus Lohjan seudun logististen palveluiden tehokkuudesta ja tilanteesta. Lohjan KTK:n laajat taustatiedot auttoivat työn kulkua koko prosessin ajan. Haasteellisin osa-alue työssä oli vastausten analysoiminen sekä argumentointi haluttuun muotoon. Lohjan KTK:lla on nyt ulkopuolisen osapuolen näkemys Lohjan KTK:n kehityksen mahdollisista linjauksista. Lohjan KTK tuntee markkina-alueensa entistä syvemmin, mikä johtaa tehokkaaseen asiakaspalveluun. Lohjan KTK:n on hyvä tutkia toimintaympäristöään ja kehittää toimintapaansa annettujen argumenttien perusteella.This Bachelor´s thesis demonstrates a logistics company´s market- and developing research. A dynamic logistics company needs to know, what kind of working environment the company is dealing with. For this reason Lohjan KTK is seeking better knowledge from customers and the market area. Lohjan KTK wants to develop services close by the customers´ daily needs. This thesis is targeted on Lohjan KTK´s old and potential customers. Lohjan KTK wants to be an effective and reliable business partner in the logistic field. This thesis includes customer - and market research. The customer - and market research was sent to over two hundred companies. These companies can be divided into, medium and large companies, which represent infrastructure - and service industry. The research material was Lohja n KTK´s company info, which included invoicing and marketing information. The implementation of the research was based on the question- and marketing forms, an analyzing form, in which it was specified to which category the company belongs to, an old customers or a potential one customer. This thesis gives an extensive view of what the customers´ real needs are in the logistic field. Lohjan KTK should intensify customer service by adding daily contacts to the customers. In this way Lohjan KTK could provide services, which add extra value to its operation. The development research was based on customer- and markets research. Suggested targets for development can provide a very effective and modern service-environment. Customers and the business environment want Lohjan KTK to be a close partner in their everyday work. In this way companies are searching innovative solutions, which have an effect on and improve their business network. As a result of the present study, several development targets and opportunities for optimizing were noticed the Lohjan KTK´s services. Future customers will have the best possible market environment to provide their logistic operations

F–3-teachers’ attitudes towards translanguaging : A qualitative study of F—3-teachers’ attitudes to multilingual students’ use of the mother tongue in Swedish teaching

Syftet med denna studie var att fördjupa kunskapen om F–3-lärares attityder till flerspråkiga elevers transspråkande i svenskundervisningen. I denna studie tillämpade vi en kvalitativ metod med semistrukturerade intervjuer. Sammanlagt intervjuade vi fem F–3-lärare som har erfarenheter av flerspråkiga elever. Utifrån dessa intervjuer har vi samlat in empiri. Resultatet visade att lärarna har positiva attityder till flerspråkiga elevers transspråkande i svenskundervisningen. De ser modersmålet som en resurs. Slutsatsen som vi kommit fram till i denna studie är att lärarna uppmuntrar eleverna till att använda sina modersmål. De ser det inte som ett hinder utan istället som ett redskap som gynnar eleverna

Las lecciones y las nuevas encrucijadas de la construcción europea

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