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

Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications

International audienceIn this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility

ADAPTASI MASYARAKAT BANTARAN SUNGAI TERHADAP BENCANA BANJIR DI KELURAHAN KOMO LUAR KOTA MANADO

Indonesia memiliki karakteristik geografis dan geologis yang sangat rentan terhadap perubahan iklim. Hal tersebut karena Indonesia merupakan Negara Kepulauan dengan daerah pantai yang luas dan sebagian besar populasi penduduk bertempat tinggal dikawasan pesisir pantai maupun daerah bantaran sungai. Kota Manado sebagai Ibu Kota Provinsi Sulawesi Utara dengan karakteristik wilayah yang dataran tinggi dan dataran rendah yang rentan terhadap bencana seperti banjir dan lain-lain. BPPD Kota Manado mencatat bencana terbesar di Kota Manado yang pernah tercatat sejak 169 tahun adalah banjir dan tanah longsor pada tanggal 15 Januari 2014. Tujuan Penelitian ini untuk mengetahui penyebab banjir yang di hadapi masyarakat, mengkaji adaptasi masyarakat bantaran sungai terhadap bencana banjir berdasarkan karakteristik sosial-ekonomi dan prilaku masyarakat , dan mengkaji adaptasi masyarakat di Kelurahan Komo Luar Kota Manado. Desain penelitian yang digunakan dalam penelitian ini adalah deskriptif kuantitatif menggunakanmetode survey dengan rancangan study kasus. Populasi dalam penelitian ini adalah 184 KK di Kelurahan Komo Luar Kota Manado yang terkena dampak dengan kriteria tinggi banjir tertinggi 3-4 meter, dan sampel dalam penelitian ini 64 responden dengan menggunakan metode purosive sampling di Kelurahan Komo Luar Kota Manado. Hasil penelitian ditemukan strategi adaptasi yang dilakukan masyarakat adalah menentukan rute eveakuasi sendiri yakni rumah mereka dan masjid, sampai saat ini alat evakuasi masih sederhana yang tersedia di masing-masing rumah warga, petugas pertolongan pertama tidak ada hingga kini petugas pertolongan pertama adalah masyarakat itu sendiri dengan saling membantu dalam pengurangan dampak dari resiko bencana bajir.Kesimpulan :Banjir di Kelurahan Komo Luar di sebabkan oleh faktor alam dan prilaku masyarakat, responden, strategi adaptasi yang dilakukan masyarakat dalam hal ini cukup baik dalam meminimalkan dampak resiko bencana banjir.Kata kunci :Adaptasi, Masyarakat Bantaran Sungai, dan Bencana Banji

Effects of urbanization on plant-pollinator interactions in the Tropics : an experimental approach using exotic plants

Land-use changes through urbanization and biological invasions both threaten plant pollinator networks. Urban areas host modified bee communities and are characterized by high proportions of exotic plants. Exotic species, either animals or plants, may compete with native species and disrupt plant–pollinator interactions. These threats are heightened in insular systems of the Southwest Pacific, where the bee fauna is generally poor and ecological networks are simplified. However, the impacts of these factors have seldom been studied in tropical contexts. To explore those questions, we installed experimental exotic plant communities in urban and natural contexts in New Caledonia, a plant diversity hotspot. For four weeks, we observed plant–pollinator interactions between local pollinators and our experimental exotic plant communities. We found a significantly higher foraging activity of exotic wild bees within the city, together with a strong plant–pollinator association between two exotic species. However, contrary to our expectations, the landscape context (urban vs. natural) had no eect on the activity of native bees. These results raise issues concerning how species introduced in plant–pollinator networks will impact the reproductive success of both native and exotic plants. Furthermore, the urban system could act as a springboard for alien species to disperse in natural systems and even invade them, leading to conservation concerns

The importance of being constrained: dealing with infeasible solutions in Differential Evolution and beyond

We argue that results produced by a heuristic optimisation algorithm cannot be considered reproducible unless the algorithm fully specifies what should be done with solutions generated outside the domain, even in the case of simple box constraints. Currently, in the field of heuristic optimisation, such specification is rarely mentioned or investigated due to the assumed triviality or insignificance of this question. Here, we demonstrate that, at least in algorithms based on Differential Evolution, this choice induces notably different behaviours - in terms of performance, disruptiveness and population diversity. This is shown theoretically (where possible) for standard Differential Evolution in the absence of selection pressure and experimentally for the standard and state-of-the-art Differential Evolution variants on special test function $f_0$ and BBOB benchmarking suite, respectively. Moreover, we demonstrate that the importance of this choice quickly grows with problem's dimensionality. Different Evolution is not at all special in this regard - there is no reason to presume that other heuristic optimisers are not equally affected by the aforementioned algorithmic choice. Thus, we urge the field of heuristic optimisation to formalise and adopt the idea of a new algorithmic component in heuristic optimisers, which we call here a strategy of dealing with infeasible solutions. This component needs to be consistently (a) specified in algorithmic descriptions to guarantee reproducibility of results, (b) studied to better understand its impact on algorithm's performance in a wider sense and (c) included in the (automatic) algorithmic design. All of these should be done even for problems with box constraints