Bioactivity of wollastonite/aerogels composites obtained from a TEOS-MTES matrix

Organic-inorganic hybrid materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS), methyltrimethoxysilane (MTES), synthetic wollastonite powders and polydimethylsiloxane (PDMS) in an ethanol solution. Aerogels were prepared from acid hydrolysis of TEOS and MTES with different volume ratio in ethanol, followed by addition of wollastonite powder and PDMS in order to obtain aerogels with 20 wt% of PDMS and 5 wt% of CaO of the total silica. Finally, when the wet gels were obtained, they were supercritically dried at 260°C and 90 bar, in ethanol. In order to obtain its bioactivity, one method for surface activation is based on a wet chemical alkaline treatment. The particular interest of this study is that we introduce hybrid aerogels, in a 1 M solution of NaOH, for 30 s at room temperature. We evaluate the bioactivity of TEOS-MTES aerogel when immersed in a static volume of simulated body fluid (SBF). An apatite layer of spherical-shaped particles of uniform size smaller than 5 microns is observed to form on the surface of the aerogels after 25 days soaking in SBF.Ministerio de Ciencia e Innovación MAT2005-01583Junta de Andalucía TEP 79

Aspects to consider for optimizing a substrate culture system with drainage recycling

In Colombia, the soilless system has been implemented in the cut flowers industry, among others, due to soil limitations. The use of substrates as growing media implies to drain around 30% of the applied fertigation solution to avoid the rhizosphere salinization. The drainage solution is spilled out to the soil producing environmental hazards and it might reach the water table; although the drainage solution could be recycled or reuse, depending upon their chemical characteristics. The nutrient uptake by the plants depends upon their phenological stage and the nutrient concentration in the solution; which could lead to ion depletion or accumulation. In general, monovalent ions are withdrawn faster than divalent ones. An efficient drainage treatment involves the automation of sensing and evaluation of ion concentration and recycling the drainage solution. The system should take into account the chemical aspects in the recycled and the new solutions in order to predict the life time of the drainage solution from their EC and pH. The system must be integrated with disinfection methods to avoid the spreading of plant pathogens. This review point out the physiological and technical bases that should be taking into account in a drainage recycling system in established crops under substrates, as a tool to take decisions more efficiently

Tailoring Organic-Organic Poly(vinylpyrrolidone) Microparticles and Fibers with Multiwalled Carbon Nanotubes for Reinforced Composites

Polymeric-based microparticles and fibers are tailorable for a wide range of common industrial and biomedical applications, while multiwalled carbon nanotubes (MWCNTs) are among the most useful macromolecules based on their outstanding electronic, mechanical, and optical properties at the nanoscale. If one combines these nanostructures with various polymeric precursors, their range of potential applications becomes even greater. One of the simplest and most affordable methods for fabricating micro- and nanostructures is electrospinning. Herein we demonstrate how MWCNTs may be used to produce tailor-made organic-organic poly(vinylpyrrolidone) (PVP) microparticles and fibers via electrospinning by studying their structural, vibrational, rheological, and mechanical properties' dependence on their solvent (ethanol (EtOH) or dimethylformamide (DMF)) and resulting morphology. Specifically, we find clear differences in morphologies from perfectly spherical and isolated microparticles to fibers mats, or a combination of fibers with entangled beads, with solvent type and concentration. On the basis of our findings, we propose that the mechanism governing the shape and size of the particles is a competition between the solvent's surface tension, dielectric constant, and viscoelastic properties. We show, based on both our experimental results and density functional theory (DFT) calculations, that OH functionalization of the MWCNTs is essential for achieving high PVP coverages and promoting the stability of the resulting PVP/MWCNT nanocomposite. Finally, by fabricating PVP/MWCNT fiber mats, we demonstrate that low concentrations (0.01-0.1 wt %) of MWCNTs led to a qualitative improvement (â250%) in the resulting mechanical properties, i.e., a reinforced composite. These results show how by controlling the solvent's dielectric constant, surface tension, and polymer concentration, one may produce tailor-made polymeric nanomaterials in combination with other organic/inorganic nanoparticles, i.e., silver, gold, or carbon allotropes, for next-generation applications

Biomass distribution efficiency of rose cv. charlotte grown in soil and substrates at second production peak

Growing plants in substrates is an alternative for the productionof roses under unfavorable soil conditions. The objective of thisstudy was to determine the biomass distribution efficiency ofrose cv. Charlotte grown in soil and substrates under greenhouseconditions until second production peak. In this trial,soil and substrates with 100% burned rice husk (100BRH); 65%burned rice husk: 35% coconut fiber (65BRH); 35% burnedrice husk: 65% coconut fiber (35BRH); and 100% coconutfiber (100CF) were used. The experimental design consistedof a randomized complete block design with three repetitions.Destructive sampling was carried out using whole plants andflowering stems at previously determined bud stages. Leaf areaand dry matter in organs were measured and growth rate andphysiological indexes were calculated. The assessed variableswere fitted to logistic and exponential models. The plants grownin substrates with BRH (burned rice husk) showed similarvalues regarding dry matter and fresh weight accumulationin organs. Plants in the soil treatment were the last ones toreach the different development stages of the flowering buds,while those that were grown in 100CF were the first ones. Thetreatments 35BRH and 100CF showed less growth of floweringstems, which was expressed in terms of relative dry matterincrease per day. The plants grown in soil showed more drymatter in leaves and stems but less in flower buds. The 65BRHtreatment showed some of the highest dry matter accumulationsin leaves, stems and flower buds and also showed the highestleaf area ratio, leaf weight ratio, and specific leaf area values

Comparison of postharvest commercial products in two varieties of spray chrysanthemum on the bogota plateau

The ornamental quality of chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura) is affected by postharvest premature senescence of foliage. The longevity of the flower stem is limited by yellowing of the foliage while the flower itself maintains ornamental value. The objective of this research was to compare the efficiency of anti-senescence and hydrating commercial products used in postharvest handling of the chrysanthemum varieties Polaris and Yellow Polaris. The variables floral longevity, relative water content (RWC) and chlorophyll content were measure. Flowering spray chrysanthemum stems underwent vase life evaluation for 10 days. In the beginning, there were differences between treatments in the content of chlorophyll; however, the onset of premature senescence symptoms on the foliage can be delayed through the application of treatment RVB clear (hydrating and bactericide, it’s contains a complex of biocide, organic acidifying and surfactant) in a hydration solution or in a mixture with the SVB treatment (foliar anti-senescence based on hormones). We determined a total chlorophyll content of 0.011 mg g-1 of leaf fresh weight as a threshold, above which no symptoms of yellowing foliage are visible in spray chrysanthemum. For the variable RWC, a differential effect of the treatments was not seen for the tested varieties. There was also no correlation between hydration status and chlorophyll content in the foliage

Aerogeles con aplicaciones en biomedicina y medioambiente

Es posible preparar materiales híbridos inorgánico-orgánicos incorporando una fase orgánica sobre un sol obtenido por hidrólisis de metalorgánico mientras se aplican ultrasonidos de alta potencia. Cuando las dos fases quedan químicamente enlazadas resulta un sono-ormosil (de ORganic MOdified SILicate) conocido también como ormosil duro. Unas de las aplicaciones de estos materiales atañe el dominio de la biotecnología pues llegan a ser bioactivos cuando contienen Ca, cumpliendo con ello el primer requisito para su validez como implantes óseos. La fuente de calcio, seleccionada para optimizar el proceso de secado supercrítico en etanol, ha sido partículas de wollastonita, (CaSiO3), material bioactivo, lo que al influir sobre el volumen poroso y el radio de los poros, permite controlar la densidad y situar la resistencia mecánica en el intervalo de valores propios de los huesos humanos esponjosos. Por otra parte, los poros pueden hacerse químicamente activos y usarse como soportes estructurales para la captación y fijación de gases.It is possible to synthesise inorganic-organic hybrid materials incorporating the organic phase to a sol prepared from a metal organic under high power ultrasounds. When both phases are chemically bonded a sono-ormosil (from ORganic MOdified SILicate) results, also known as hard ormosil. One of the applications of these materials concerns the biotechnologies since they become bioactive when are doped with Ca, fulfilling this way the preliminary condition to be considered for bone implants. The addition of silicate particles allows modifying the pore volume and radius. We have used these gels with particles, as precursor of the bioactive component, in order to act on the porosity for controlling the density and adequate the mechanical strength to that of the human cancellous bone. In like manner, the pores becomes chemically active and be used as structural support for noxious atmospheric gas sequestration

Analysis of the electric conductivity and ph behaviors in recycled drainage solution of rose cv. charlotte plants grown in substrate

In open soilless cropping systems contamination from nutrientlixiviation is generated making it necessary to design closed orsemi-closed systems, which require the determination of themaximum saline levels in recycling solutions. In this study, theelectric conductivity (EC) and pH behaviors were analyzed indrainage solution intended for recycling in the crop; in addi-tion, parameters were used to estimate nutrient availability forthe plants in a substrate based cropping system. This researchproject was carried out under greenhouse conditions in the mu-nicipality of Mosquera (Colombia). Rose cv. Charlotte graftedon ‘Natal briar’ stocks were used, sown in pots arranged onelevated beds, 15 m in length. This project was carried out usinga split-plot design with sub-plots (with the substrate as the mainplot and the recycling as the sub-plot), three kinds of substrateand three recycling percentages (0, 50, and 100%), for a total of27 experimental units. Substrate mixtures based on burned ricehusk and coconut fiber were used. Recycling during one harvestcycle of the roses did not show EC and pH values above thosethat are considered to have a negative impact on production;however, an increasing behavior in the EC and pH values wasobserved. Likewise, no significant differences between the 50and 100% recycling were observed, which means 100% recyclingcan be used, optimizing nutrient use and water conservation

Aspects to consider for optimizing a substrate culture system with drainage recycling

In Colombia, the soilless system has been implemented in the cut flowers industry, among others, due to soil limitations. The use of substrates as growing media implies to drain around 30% of the applied fertigation solution to avoid the rhizosphere salinization. The drainage solution is spilled out to the soil producing environmental hazards and it might reach the water table; although the drainage solution could be recycled or reuse, depending upon their chemical characteristics. The nutrient uptake by the plants depends upon their phenological stage and the nutrient concentration in the solution; which could lead to ion depletion or accumulation. In general, monovalent ions are withdrawn faster than divalent ones. An efficient drainage treatment involves the automation of sensing and evaluation of ion concentration and recycling the drainage solution. The system should take into account the chemical aspects in the recycled and the new solutions in order to predict the life time of the drainage solution from their EC and pH. The system must be integrated with disinfection methods to avoid the spreading of plant pathogens. This review point out the physiological and technical bases that should be taking into account in a drainage recycling system in established crops under substrates, as a tool to take decisions more efficiently

Biomass distribution efficiency of rose cv. Charlotte grown in soil and substrates at second production peak

Growing plants in substrates is an alternative for the production of roses under unfavorable soil conditions. The objective of this study was to determine the biomass distribution efficiency of rose cv. Charlotte grown in soil and substrates under greenhouse conditions until second production peak. In this trial, soil and substrates with 100% burned rice husk (100BR H); 65% burned rice husk: 35% coconut fiber (65BR H); 35% burned rice husk: 65% coconut fiber (35BR H); and 100% coconut fiber (100CF) were used. The experimental design consisted of a randomized complete block design with three repetitions. Destructive sampling was carried out using whole plants and flowering stems at previously determined bud stages. Leaf area and dry matter in organs were measured and growth rate and physiological indexes were calculated. The assessed variables were fitted to logistic and exponential models. The plants grown in substrates with BR H (burned rice husk) showed similar values regarding dry matter and fresh weight accumulation in organs. Plants in the soil treatment were the last ones to reach the different development stages of the flowering buds, while those that were grown in 100CF were the first ones. The treatments 35BR H and 100CF showed less growth of flowering stems, which was expressed in terms of relative dry matter increase per day. The plants grown in soil showed more dry matter in leaves and stems but less in flower buds. The 65BR H treatment showed some of the highest dry matter accumulations in leaves, stems and flower buds and also showed the highest leaf area ratio, leaf weight ratio, and specific leaf area value

Avances sobre fertirriego en la floricultura colombiana

Caracteristicas fundamentales del proyecto "Producción más limpia de rosa y clavel con dos técnicas de cultivo sin suelo en la Sabana de Bogotá" -- Aspectos de desarrollo y calidad -- Nutrición vegetal -- Programación de riego, fertirriego y recirculación.xii, 499 página