Search results for "Natural materials"
showing 10 items of 16 documents
Thermal and structural properties of a hemp–lime biocomposite
2013
Abstract The need to reduce greenhouse gases emission produced by the building sector leads to the research of renewable and less impacting materials that can replace traditional ones. This subject has encouraged new researches on biocomposite concretes with the aim to exploit renewable resources like vegetal fibres intended as materials whose production processes are generally characterized by low costs and energy demand. This biocomposite is obviously much lighter than concrete and, therefore, can be suitably used in such cases where a structure cannot be overloaded, for instance in the realization of a green covering on top of a preexistent building. In this work, a first analysis of the…
3 - 4 gadus vecu bērnu sensorās attīstības veicināšana ar dabas materiāliem
2015
Diplomdarba tēma ir ”3-4 gadus vecu bērnu sensorās attīstības veicināšana ar dabas materiāliem”. Pētījuma objekts: Pirmsskolas pedagoģiskais process, izmantojot dabas materiālus. Pētījuma priekšmets: 3-4 gadus vecu bērnu sensorā attīstība. Pētījuma mērķis: Atlasīt un pārbaudīt metodes bērnu sensorās attīstības veicināšanai, izmantojot dabas materiālus. Darbā tiek pievērsta uzmanība bērna smadzeņu uzbūves un agrīnas attīstības īpatnībām kā galvenajam faktoram, kas pamatos nosaka visu turpmāko bērna sensoro spēju potenciālu, uzsvērta iedzimtības, apkārtējās vides un audzināšanas loma, sniegts izvērsts bērna maņu orgānu sistēmas raksturojums, aplūkots pedagoģisko pasākumu kopums, kā ar dabas n…
Effect of areal weight and chemical treatment on the mechanical properties of bidirectional flax fabrics reinforced composites
2010
Abstract In this paper several bidirectional flax fibers, usually used to made curtains, were employed as reinforcement of an epoxy matrix. Four different laminates were made by a vacuum bagging process, with varying both the areal weight and the treatment of the fabric. These structures were mechanically investigated carrying out both tensile and three point flexural tests. In order to evaluate the effect of the identified variables on the mechanical parameters (i.e. Young modulus and maximum stress) a statistical analysis was performed. Finally, by comparing the flax composite with a glass one, the convenience of the replacement of glass fiber was investigated in term of cost, weight and …
El futuro de los plásticos o los plásticos del futuro
2020
espanolEn los ultimos tiempos politicos, activistas ambientales, periodistas y otros lideres de opinion han dirigido sus armas contra los plasticos. Este mal concepto nace como resultado de los cambios en el entorno como consecuencia de la utilizacion de nuevas fuentes de energia, tanto nuclear como la de combustibles fosiles y el desarrollo de la industria petroquimica en especial la de los plasticos que se da a partir del descubrimiento del petroleo. Sin embargo y a pesar de las consideraciones ambientales el plastico ha construido nuestro mundo hasta el punto en que hoy es dificil imaginar nuestra vida sin el. Muchos disenadores han sostenido desde mediados del siglo XX, que los articulo…
Evagination of Cells Controls Bio-Silica Formation and Maturation during Spicule Formation in Sponges
2011
The enzymatic-silicatein mediated formation of the skeletal elements, the spicules of siliceous sponges starts intracellularly and is completed extracellularly. With Suberites domuncula we show that the axial growth of the spicules proceeds in three phases: (I) formation of an axial canal; (II) evagination of a cell process into the axial canal, and (III) assembly of the axial filament composed of silicatein. During these phases the core part of the spicule is synthesized. Silicatein and its substrate silicate are stored in silicasomes, found both inside and outside of the cellular extension within the axial canal, as well as all around the spicule. The membranes of the silicasomes are inte…
Can biological structures be natural and sustainable capsules?
2015
Flavor and fragrance molecules are used in many industrial fields such as food, cosmetics, tissues, pharmacy, agriculture (pheromones) etc. As most actives have a specific target and are fragile molecules, encapsulation processes have been developed for their use. These technologies are efficient to avoid loss of actives, dissemination out of the target and subsequent pollution, and to protect molecules up to their target. Several processes have been developed responding to the numerous situations encountered (e.g., protection against air, temperature, light, pH; masking or revealing sensorial properties of the molecule; release during the process, in the plate, in the mouth, etc.). However…
Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.
2018
‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…
Sapropel as a Binder: Properties and Application Possibilities for Composite Materials
2015
Recent development trends largely look for possibilities of a wider use of natural materials and local resources. In this perspective, the use of organic rich lake sediment - sapropel - as a binding material in line with other environmentally friendly filling materials can be considered as a challenge. Sapropel itself is a valuable resource with multiple areas of application, for example, medicine, veterinary, agriculture, livestock farming, balneology, cosmetic applications, construction, and its application options have been widely studied in the 20th century in the Baltic countries, Ukraine and Russia. Birch wood fibre and sanding dust, hemp shives, 'Aerosil' are used as a filler and thr…
An investigation into the fracture behaviour of honeycombs with density gradients
2020
International audience; In this study we perform an experimental and computational investigation about the fracture behaviour of polymer honeycombs presenting gradients in terms of lattice density. Such lattice relative density variations are introduced with the aim of mimicking the micro-morphology encountered in some natural materials, such as several kinds of woods, which seems related to the ability of the corresponding macro-material to delay the propagation of fracture under certain conditions. Starting from the conclusions of previous computational analyses, we perform a few experimental tensile tests on ABS model honeycombs obtained by additive manufacturing, with the aim of getting…
The possibilities of using low-cost fibrous natural materials as sorbents for removing aliphatic hydrocarbons (C6-C15) from an aqueous solution
2020
Sorption of oil-related products (including mainly the propellants) is the basic process that coun-teracts spreading these types of pollution into the environment. Plenty of synthetic substances (including multi-component petroleum products) must be removed both from the fresh and ground-water. The aim of this study was to compare the possibilities of using natural fibrous materials (also weed or waste materials): broadleaf cattail (Typha latifolia L.) seeds, peat and coconut fiber as sorbents of aliphatic hydrocarbons from an aqueous solution. In order to increase sorptive capacity, tested materials were mercerized in hot (80°C) NaOH for sorption properties improvement. The removal of alip…